Extraction of advanced geospatial intelligence (AGI) from commercial synthetic aperture radar imagery

NASA Astrophysics Data System (ADS)

Kanberoglu, Berkay; Frakes, David

2017-04-01

The extraction of objects from advanced geospatial intelligence (AGI) products based on synthetic aperture radar (SAR) imagery is complicated by a number of factors. For example, accurate detection of temporal changes represented in two-color multiview (2CMV) AGI products can be challenging because of speckle noise susceptibility and false positives that result from small orientation differences between objects imaged at different times. These cases of apparent motion can result in 2CMV detection, but they obviously differ greatly in terms of significance. In investigating the state-of-the-art in SAR image processing, we have found that differentiating between these two general cases is a problem that has not been well addressed. We propose a framework of methods to address these problems. For the detection of the temporal changes while reducing the number of false positives, we propose using adaptive object intensity and area thresholding in conjunction with relaxed brightness optical flow algorithms that track the motion of objects across time in small regions of interest. The proposed framework for distinguishing between actual motion and misregistration can lead to more accurate and meaningful change detection and improve object extraction from a SAR AGI product. Results demonstrate the ability of our techniques to reduce false positives up to 60%.

Limited Agreement of Independent RNAi Screens for Virus-Required Host Genes Owes More to False-Negative than False-Positive Factors

PubMed Central

Wang, Zhishi; Craven, Mark; Newton, Michael A.; Ahlquist, Paul

2013-01-01

Systematic, genome-wide RNA interference (RNAi) analysis is a powerful approach to identify gene functions that support or modulate selected biological processes. An emerging challenge shared with some other genome-wide approaches is that independent RNAi studies often show limited agreement in their lists of implicated genes. To better understand this, we analyzed four genome-wide RNAi studies that identified host genes involved in influenza virus replication. These studies collectively identified and validated the roles of 614 cell genes, but pair-wise overlap among the four gene lists was only 3% to 15% (average 6.7%). However, a number of functional categories were overrepresented in multiple studies. The pair-wise overlap of these enriched-category lists was high, ∼19%, implying more agreement among studies than apparent at the gene level. Probing this further, we found that the gene lists implicated by independent studies were highly connected in interacting networks by independent functional measures such as protein-protein interactions, at rates significantly higher than predicted by chance. We also developed a general, model-based approach to gauge the effects of false-positive and false-negative factors and to estimate, from a limited number of studies, the total number of genes involved in a process. For influenza virus replication, this novel statistical approach estimates the total number of cell genes involved to be ∼2,800. This and multiple other aspects of our experimental and computational results imply that, when following good quality control practices, the low overlap between studies is primarily due to false negatives rather than false-positive gene identifications. These results and methods have implications for and applications to multiple forms of genome-wide analysis. PMID:24068911

39 CFR 946.2 - Disposition of property of apparent owners.

Code of Federal Regulations, 2010 CFR

2010-07-01

... DISPOSITION OF STOLEN MAIL MATTER AND PROPERTY ACQUIRED BY THE POSTAL INSPECTION SERVICE FOR USE AS EVIDENCE § 946.2 Disposition of property of apparent owners. Where an apparent owner of property subject to this... 39 Postal Service 1 2010-07-01 2010-07-01 false Disposition of property of apparent owners. 946.2...

39 CFR 946.2 - Disposition of property of apparent owners.

Code of Federal Regulations, 2011 CFR

2011-07-01

... DISPOSITION OF STOLEN MAIL MATTER AND PROPERTY ACQUIRED BY THE POSTAL INSPECTION SERVICE FOR USE AS EVIDENCE § 946.2 Disposition of property of apparent owners. Where an apparent owner of property subject to this... 39 Postal Service 1 2011-07-01 2011-07-01 false Disposition of property of apparent owners. 946.2...

Apparently abnormal Wechsler Memory Scale index score patterns in the normal population.

PubMed

Carrasco, Roman Marcus; Grups, Josefine; Evans, Brittney; Simco, Edward; Mittenberg, Wiley

2015-01-01

Interpretation of the Wechsler Memory Scale-Fourth Edition may involve examination of multiple memory index score contrasts and similar comparisons with Wechsler Adult Intelligence Scale-Fourth Edition ability indexes. Standardization sample data suggest that 15-point differences between any specific pair of index scores are relatively uncommon in normal individuals, but these base rates refer to a comparison between a single pair of indexes rather than multiple simultaneous comparisons among indexes. This study provides normative data for the occurrence of multiple index score differences calculated by using Monte Carlo simulations and validated against standardization data. Differences of 15 points between any two memory indexes or between memory and ability indexes occurred in 60% and 48% of the normative sample, respectively. Wechsler index score discrepancies are normally common and therefore not clinically meaningful when numerous such comparisons are made. Explicit prior interpretive hypotheses are necessary to reduce the number of index comparisons and associated false-positive conclusions. Monte Carlo simulation accurately predicts these false-positive rates.

49 CFR 98.3 - Reports of apparent violations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 1 2010-10-01 2010-10-01 false Reports of apparent violations. 98.3 Section 98.3 Transportation Office of the Secretary of Transportation ENFORCEMENT OF RESTRICTIONS ON POST-EMPLOYMENT ACTIVITIES Administration of Enforcement Proceedings § 98.3 Reports of apparent violations. Any person may...

Missing Fragments: Detecting Cooperative Binding in Fragment-Based Drug Design

PubMed Central

2012-01-01

The aim of fragment-based drug design (FBDD) is to identify molecular fragments that bind to alternate subsites within a given binding pocket leading to cooperative binding when linked. In this study, the binding of fragments to human phenylethanolamine N-methyltransferase is used to illustrate how (a) current protocols may fail to detect fragments that bind cooperatively, (b) theoretical approaches can be used to validate potential hits, and (c) apparent false positives obtained when screening against cocktails of fragments may in fact indicate promising leads. PMID:24900472

Canine serum thyroglobulin autoantibodies in health, hypothyroidism and non-thyroidal illness.

PubMed

Dixon, R M; Mooney, C T

1999-06-01

Thyroglobulin autoantibody (TGAA) was measured in serum from dogs with hypothyroidism (n = 42), non-thyroidal illness (NTI) (n = 77) and clinically healthy dogs (n = 70) using a commercially available enzyme immunoassay kit. Precision studies were consistent with good intra-assay and inter-assay repeatability. TGAA positive results occurred in 15 of the 42 (36 per cent) hypothyroid and four healthy dogs of the remaining 147 animals resulting in a lower incidence of false positive results than obtained with previous TGAA assays. The presence of TGAA was not influenced by age, sex, neutering or pedigree status. Of the four apparently healthy TGAA -positive dogs, two had additional clinicopathological evidence of hypothyroidism. TGAA was positive in 43 per cent of hypothyroid dogs with unexpectedly normal serum c TSH concentrations and was particularly useful in the classification of these cases. Copyright 1999 W.B. Saunders Company Ltd.

Rethinking the Relationship between Social Experience and False-Belief Understanding: A Mentalistic Account.

PubMed

Roby, Erin; Scott, Rose M

2016-01-01

It was long assumed that the capacity to represent false beliefs did not emerge until at least age four, as evidenced by children's performance on elicited-response tasks. However, recent evidence that infants appear to demonstrate false-belief understanding when tested with alternative, non-elicited-response measures has led some researchers to conclude that the capacity to represent beliefs emerges in the 1st year of life. This mentalistic view has been criticized for failing to offer an explanation for the well-established positive associations between social factors and preschoolers' performance on elicited-response false-belief tasks. In this paper, we address this criticism by offering an account that reconciles these associations with the mentalistic claim that false-belief understanding emerges in infancy. We propose that rather than facilitating the emergence of the capacity to represent beliefs, social factors facilitate the use of this ability via effects on attention, inference, retrieval, and response production. Our account predicts that the relationship between social factors and false-belief understanding should not be specific to preschoolers' performance in elicited-response tasks: this relationship should be apparent across the lifespan in a variety of paradigms. We review an accumulating body of evidence that supports this prediction.

49 CFR 98.3 - Reports of apparent violations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 1 2011-10-01 2011-10-01 false Reports of apparent violations. 98.3 Section 98.3 Transportation Office of the Secretary of Transportation ENFORCEMENT OF RESTRICTIONS ON POST-EMPLOYMENT ACTIVITIES Administration of Enforcement Proceedings § 98.3 Reports of apparent violations. Any person may report, to the Assistant General...

Facing the problem of "false positives": re-assessment and improvement of a multiplex RT-PCR procedure for the diagnosis of A. flavus mycotoxin producers.

PubMed

Degola, F; Berni, E; Spotti, E; Ferrero, I; Restivo, F M

2009-02-28

The aim of our research project was to consolidate a multiplex RT-PCR protocol to detect aflatoxigenic strains of Aspergillus flavus. Several independent A. flavus strains were isolated from corn and flour samples from the North of Italy and from three European countries. Aflatoxin producing/not producing phenotype was assessed by qualitative and quantitative assays at day five of growth in aflatoxin inducing conditions. Expression of 16 genes belonging to the aflatoxin cluster was assayed by multiplex or monomeric RT-PCR. There is a good correlation between gene expression and aflatoxin production. Strains that apparently transcribed all the relevant genes but did not release aflatoxin in the medium ("false positives") were re-assessed for mycotoxin production after extended growth in inducing condition. All the "false positive" strains in actual fact were positive when aflatoxin determination was performed after 10 days of growth. These strains should then be re-classified as "slow aflatoxin accumulators". To optimise the diagnostic procedure, a quintuplex RT-PCR procedure was designed consisting of a primer set directed against four informative aflatoxin cluster genes and the beta-tubulin gene as an internal amplification control. In conclusion we have provided evidence for the robustness and reliability of our RT-PCR protocol in discriminating mycotoxin producer from non-producer strains of A. flavus. and the molecular procedure we devised is a promising tool with which to screen and control the endemic population of A. flavus colonising different areas of the World.

Avoiding false positive antigen detection by flow cytometry on blood cell derived microparticles: the importance of an appropriate negative control.

PubMed

Crompot, Emerence; Van Damme, Michael; Duvillier, Hugues; Pieters, Karlien; Vermeesch, Marjorie; Perez-Morga, David; Meuleman, Nathalie; Mineur, Philippe; Bron, Dominique; Lagneaux, Laurence; Stamatopoulos, Basile

2015-01-01

Microparticles (MPs), also called microvesicles (MVs) are plasma membrane-derived fragments with sizes ranging from 0.1 to 1μm. Characterization of these MPs is often performed by flow cytometry but there is no consensus on the appropriate negative control to use that can lead to false positive results. We analyzed MPs from platelets, B-cells, T-cells, NK-cells, monocytes, and chronic lymphocytic leukemia (CLL) B-cells. Cells were purified by positive magnetic-separation and cultured for 48h. Cells and MPs were characterized using the following monoclonal antibodies (CD19,20 for B-cells, CD3,8,5,27 for T-cells, CD16,56 for NK-cells, CD14,11c for monocytes, CD41,61 for platelets). Isolated MPs were stained with annexin-V-FITC and gated between 300nm and 900nm. The latex bead technique was then performed for easy detection of MPs. Samples were analyzed by Transmission (TEM) and Scanning Electron microscopy (SEM). Annexin-V positive events within a gate of 300-900nm were detected and defined as MPs. Our results confirmed that the characteristic antigens CD41/CD61 were found on platelet-derived-MPs validating our technique. However, for MPs derived from other cell types, we were unable to detect any antigen, although they were clearly expressed on the MP-producing cells in the contrary of several data published in the literature. Using the latex bead technique, we confirmed detection of CD41,61. However, the apparent expression of other antigens (already deemed positive in several studies) was determined to be false positive, indicated by negative controls (same labeling was used on MPs from different origins). We observed that mother cell antigens were not always detected on corresponding MPs by direct flow cytometry or latex bead cytometry. Our data highlighted that false positive results could be generated due to antibody aspecificity and that phenotypic characterization of MPs is a difficult field requiring the use of several negative controls.

Avoiding False Positive Antigen Detection by Flow Cytometry on Blood Cell Derived Microparticles: The Importance of an Appropriate Negative Control

PubMed Central

Crompot, Emerence; Van Damme, Michael; Duvillier, Hugues; Pieters, Karlien; Vermeesch, Marjorie; Perez-Morga, David; Meuleman, Nathalie; Mineur, Philippe; Bron, Dominique; Lagneaux, Laurence; Stamatopoulos, Basile

2015-01-01

Background Microparticles (MPs), also called microvesicles (MVs) are plasma membrane-derived fragments with sizes ranging from 0.1 to 1μm. Characterization of these MPs is often performed by flow cytometry but there is no consensus on the appropriate negative control to use that can lead to false positive results. Materials and Methods We analyzed MPs from platelets, B-cells, T-cells, NK-cells, monocytes, and chronic lymphocytic leukemia (CLL) B-cells. Cells were purified by positive magnetic-separation and cultured for 48h. Cells and MPs were characterized using the following monoclonal antibodies (CD19,20 for B-cells, CD3,8,5,27 for T-cells, CD16,56 for NK-cells, CD14,11c for monocytes, CD41,61 for platelets). Isolated MPs were stained with annexin-V-FITC and gated between 300nm and 900nm. The latex bead technique was then performed for easy detection of MPs. Samples were analyzed by Transmission (TEM) and Scanning Electron microscopy (SEM). Results Annexin-V positive events within a gate of 300-900nm were detected and defined as MPs. Our results confirmed that the characteristic antigens CD41/CD61 were found on platelet-derived-MPs validating our technique. However, for MPs derived from other cell types, we were unable to detect any antigen, although they were clearly expressed on the MP-producing cells in the contrary of several data published in the literature. Using the latex bead technique, we confirmed detection of CD41,61. However, the apparent expression of other antigens (already deemed positive in several studies) was determined to be false positive, indicated by negative controls (same labeling was used on MPs from different origins). Conclusion We observed that mother cell antigens were not always detected on corresponding MPs by direct flow cytometry or latex bead cytometry. Our data highlighted that false positive results could be generated due to antibody aspecificity and that phenotypic characterization of MPs is a difficult field requiring the use of several negative controls. PMID:25978814

Simultaneous Genotype Calling and Haplotype Phasing Improves Genotype Accuracy and Reduces False-Positive Associations for Genome-wide Association Studies

PubMed Central

Browning, Brian L.; Yu, Zhaoxia

2009-01-01

We present a novel method for simultaneous genotype calling and haplotype-phase inference. Our method employs the computationally efficient BEAGLE haplotype-frequency model, which can be applied to large-scale studies with millions of markers and thousands of samples. We compare genotype calls made with our method to genotype calls made with the BIRDSEED, CHIAMO, GenCall, and ILLUMINUS genotype-calling methods, using genotype data from the Illumina 550K and Affymetrix 500K arrays. We show that our method has higher genotype-call accuracy and yields fewer uncalled genotypes than competing methods. We perform single-marker analysis of data from the Wellcome Trust Case Control Consortium bipolar disorder and type 2 diabetes studies. For bipolar disorder, the genotype calls in the original study yield 25 markers with apparent false-positive association with bipolar disorder at a p < 10−7 significance level, whereas genotype calls made with our method yield no associated markers at this significance threshold. Conversely, for markers with replicated association with type 2 diabetes, there is good concordance between genotype calls used in the original study and calls made by our method. Results from single-marker and haplotypic analysis of our method's genotype calls for the bipolar disorder study indicate that our method is highly effective at eliminating genotyping artifacts that cause false-positive associations in genome-wide association studies. Our new genotype-calling methods are implemented in the BEAGLE and BEAGLECALL software packages. PMID:19931040

Rethinking the Relationship between Social Experience and False-Belief Understanding: A Mentalistic Account

PubMed Central

Roby, Erin; Scott, Rose M.

2016-01-01

It was long assumed that the capacity to represent false beliefs did not emerge until at least age four, as evidenced by children’s performance on elicited-response tasks. However, recent evidence that infants appear to demonstrate false-belief understanding when tested with alternative, non-elicited-response measures has led some researchers to conclude that the capacity to represent beliefs emerges in the 1st year of life. This mentalistic view has been criticized for failing to offer an explanation for the well-established positive associations between social factors and preschoolers’ performance on elicited-response false-belief tasks. In this paper, we address this criticism by offering an account that reconciles these associations with the mentalistic claim that false-belief understanding emerges in infancy. We propose that rather than facilitating the emergence of the capacity to represent beliefs, social factors facilitate the use of this ability via effects on attention, inference, retrieval, and response production. Our account predicts that the relationship between social factors and false-belief understanding should not be specific to preschoolers’ performance in elicited-response tasks: this relationship should be apparent across the lifespan in a variety of paradigms. We review an accumulating body of evidence that supports this prediction. PMID:27857702

Biases in detection of apparent “weekend effect” on outcome with administrative coding data: population based study of stroke

PubMed Central

Li, Linxin

2016-01-01

Objectives To determine the accuracy of coding of admissions for stroke on weekdays versus weekends and any impact on apparent outcome. Design Prospective population based stroke incidence study and a scoping review of previous studies of weekend effects in stroke. Setting Primary and secondary care of all individuals registered with nine general practices in Oxfordshire, United Kingdom (OXVASC, the Oxford Vascular Study). Participants All patients with clinically confirmed acute stroke in OXVASC identified with multiple overlapping methods of ascertainment in 2002-14 versus all acute stroke admissions identified by hospital diagnostic and mortality coding alone during the same period. Main outcomes measures Accuracy of administrative coding data for all patients with confirmed stroke admitted to hospital in OXVASC. Difference between rates of “false positive” or “false negative” coding for weekday and weekend admissions. Impact of inaccurate coding on apparent case fatality at 30 days in weekday versus weekend admissions. Weekend effects on outcomes in patients with confirmed stroke admitted to hospital in OXVASC and impacts of other potential biases compared with those in the scoping review. Results Among 92 728 study population, 2373 episodes of acute stroke were ascertained in OXVASC, of which 826 (34.8%) mainly minor events were managed without hospital admission, 60 (2.5%) occurred out of the area or abroad, and 195 (8.2%) occurred in hospital during an admission for a different reason. Of 1292 local hospital admissions for acute stroke, 973 (75.3%) were correctly identified by administrative coding. There was no bias in distribution of weekend versus weekday admission of the 319 strokes missed by coding. Of 1693 admissions for stroke identified by coding, 1055 (62.3%) were confirmed to be acute strokes after case adjudication. Among the 638 false positive coded cases, patients were more likely to be admitted on weekdays than at weekends (536 (41.0%) v 102 (26.5%); P<0.001), partly because of weekday elective admissions after previous stroke being miscoded as new stroke episodes (267 (49.8%) v 26 (25.5%); P<0.001). The 30 day case fatality after these elective admissions was lower than after confirmed acute stroke admissions (11 (3.8%) v 233 (22.1%); P<0.001). Consequently, relative 30 day case fatality for weekend versus weekday admissions differed (P<0.001) between correctly coded acute stroke admissions and false positive coding cases. Results were consistent when only the 1327 emergency cases identified by “admission method” from coding were included, with more false positive cases with low case fatality (35 (14.7%)) being included for weekday versus weekend admissions (190 (19.5%) v 48 (13.7%), P<0.02). Among all acute stroke admissions in OXVASC, there was no imbalance in baseline stroke severity for weekends versus weekdays and no difference in case fatality at 30 days (adjusted odds ratio 0.85, 95% confidence interval 0.63 to 1.15; P=0.30) or any adverse “weekend effect” on modified Rankin score at 30 days (0.78, 0.61 to 0.99; P=0.04) or one year (0.76, 0.59 to 0.98; P=0.03) among incident strokes. Conclusion Retrospective studies of UK administrative hospital coding data to determine “weekend effects” on outcome in acute medical conditions, such as stroke, can be undermined by inaccurate coding, which can introduce biases that cannot be reliably dealt with by adjustment for case mix. PMID:27185754

False-positive result when a diphenylcarbazide spot test is used on trivalent chromium-passivated zinc surfaces.

PubMed

Reveko, Valeriia; Lampert, Felix; Din, Rameez U; Thyssen, Jacob P; Møller, Per

2018-05-01

A colorimetric 1,5-diphenylcarbazide (DPC)-based spot test can be used to identify hexavalent chromium on various metallic and leather surfaces. DPC testing on trivalent chromium-passivated zinc surfaces has unexpectedly given positive results in some cases, apparently indicating the presence of hexavalent chromium; however, the presence of hexavalent chromium has never been confirmed with more sensitive and accurate test methods. To examine the presence of hexavalent chromium on trivalent chromium-passivated zinc surfaces with a DPC-based spot test. A colorimetric DPC spot test was used for the initial detection of hexavalent chromium on new and 1-year-aged trivalent chromium-passivated zinc surfaces. Then, X-ray photoelectron spectroscopy (XPS) was performed for all samples. The DPC spot test indicated the presence of hexavalent chromium in aged, but not new, trivalent chromium passivation on zinc; however, subsequent analysis by XPS could not confirm the presence of chromium in a hexavalent state. Unintended oxidation of DPC induced by atmospheric corrosion is suggested as a possible reason for the false-positive reaction of the DPC test on a trivalent chromium-passivated zinc surface. Further validation of the use of the DPC test for chromium-containing metallic surfaces is required. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Do Optimal Prognostic Thresholds in Continuous Physiological Variables Really Exist? Analysis of Origin of Apparent Thresholds, with Systematic Review for Peak Oxygen Consumption, Ejection Fraction and BNP

PubMed Central

Leong, Tora; Rehman, Michaela B.; Pastormerlo, Luigi Emilio; Harrell, Frank E.; Coats, Andrew J. S.; Francis, Darrel P.

2014-01-01

Background Clinicians are sometimes advised to make decisions using thresholds in measured variables, derived from prognostic studies. Objectives We studied why there are conflicting apparently-optimal prognostic thresholds, for example in exercise peak oxygen uptake (pVO2), ejection fraction (EF), and Brain Natriuretic Peptide (BNP) in heart failure (HF). Data Sources and Eligibility Criteria Studies testing pVO2, EF or BNP prognostic thresholds in heart failure, published between 1990 and 2010, listed on Pubmed. Methods First, we examined studies testing pVO2, EF or BNP prognostic thresholds. Second, we created repeated simulations of 1500 patients to identify whether an apparently-optimal prognostic threshold indicates step change in risk. Results 33 studies (8946 patients) tested a pVO2 threshold. 18 found it prognostically significant: the actual reported threshold ranged widely (10–18 ml/kg/min) but was overwhelmingly controlled by the individual study population's mean pVO2 (r = 0.86, p<0.00001). In contrast, the 15 negative publications were testing thresholds 199% further from their means (p = 0.0001). Likewise, of 35 EF studies (10220 patients), the thresholds in the 22 positive reports were strongly determined by study means (r = 0.90, p<0.0001). Similarly, in the 19 positives of 20 BNP studies (9725 patients): r = 0.86 (p<0.0001). Second, survival simulations always discovered a “most significant” threshold, even when there was definitely no step change in mortality. With linear increase in risk, the apparently-optimal threshold was always near the sample mean (r = 0.99, p<0.001). Limitations This study cannot report the best threshold for any of these variables; instead it explains how common clinical research procedures routinely produce false thresholds. Key Findings First, shifting (and/or disappearance) of an apparently-optimal prognostic threshold is strongly determined by studies' average pVO2, EF or BNP. Second, apparently-optimal thresholds always appear, even with no step in prognosis. Conclusions Emphatic therapeutic guidance based on thresholds from observational studies may be ill-founded. We should not assume that optimal thresholds, or any thresholds, exist. PMID:24475020

Characterization of Exoplanet Atmospheres and Kepler Planet Candidates with Multi-Color Photometry from the Gran Telescopio Canarias

NASA Astrophysics Data System (ADS)

Colon, Knicole; Ford, E. B.

2012-01-01

With over 180 confirmed transiting exoplanets and NASA's Kepler mission's recent discovery of over 1200 transiting exoplanet candidates, we can conduct detailed investigations into the (i) properties of exoplanet atmospheres and (ii) false positive rates for planet search surveys. To aid these investigations, we developed a novel technique of using the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) installed on the 10.4-meter Gran Telescopio Canarias (GTC) to acquire near-simultaneous multi-color photometry of (i) HD 80606b in bandpasses around the potassium (K I) absorption feature, (ii) GJ 1214b in bandpasses around a possible methane absorption feature and (iii) several Kepler planet candidates. For HD 80606b, we measure a significant color change during transit between wavelengths that probe the K I line core and the K I wing, equivalent to a 4.2% change in the apparent planetary radius. We hypothesize that the excess absorption may be due to K I in a high-speed wind being driven from the exoplanet's exosphere. This is one of the first detections of K I in an exoplanet atmosphere. For GJ 1214b, we compare the transit depths measured "on” and "off” a possible methane absorption feature and use our results to help resolve conflicting results from other studies regarding the composition of this super-Earth-size planet's atmosphere. For Kepler candidates, we use the color change during transit to reject candidates that are false positives (e.g., a blend with an eclipsing binary either in the background/foreground or bound to the target star). We target small planets (<6 Earth radii) with short orbital periods (<6 days), since eclipsing binaries can mimic planets in this regime. Our results include identification of two false positives and test recent predictions of the false positive rates for the Kepler sample. This research demonstrates the value of the GTC for exoplanet follow-up.

Biases in detection of apparent "weekend effect" on outcome with administrative coding data: population based study of stroke.

PubMed

Li, Linxin; Rothwell, Peter M

2016-05-16

 To determine the accuracy of coding of admissions for stroke on weekdays versus weekends and any impact on apparent outcome.  Prospective population based stroke incidence study and a scoping review of previous studies of weekend effects in stroke.  Primary and secondary care of all individuals registered with nine general practices in Oxfordshire, United Kingdom (OXVASC, the Oxford Vascular Study).  All patients with clinically confirmed acute stroke in OXVASC identified with multiple overlapping methods of ascertainment in 2002-14 versus all acute stroke admissions identified by hospital diagnostic and mortality coding alone during the same period.  Accuracy of administrative coding data for all patients with confirmed stroke admitted to hospital in OXVASC. Difference between rates of "false positive" or "false negative" coding for weekday and weekend admissions. Impact of inaccurate coding on apparent case fatality at 30 days in weekday versus weekend admissions. Weekend effects on outcomes in patients with confirmed stroke admitted to hospital in OXVASC and impacts of other potential biases compared with those in the scoping review.  Among 92 728 study population, 2373 episodes of acute stroke were ascertained in OXVASC, of which 826 (34.8%) mainly minor events were managed without hospital admission, 60 (2.5%) occurred out of the area or abroad, and 195 (8.2%) occurred in hospital during an admission for a different reason. Of 1292 local hospital admissions for acute stroke, 973 (75.3%) were correctly identified by administrative coding. There was no bias in distribution of weekend versus weekday admission of the 319 strokes missed by coding. Of 1693 admissions for stroke identified by coding, 1055 (62.3%) were confirmed to be acute strokes after case adjudication. Among the 638 false positive coded cases, patients were more likely to be admitted on weekdays than at weekends (536 (41.0%) v 102 (26.5%); P<0.001), partly because of weekday elective admissions after previous stroke being miscoded as new stroke episodes (267 (49.8%) v 26 (25.5%); P<0.001). The 30 day case fatality after these elective admissions was lower than after confirmed acute stroke admissions (11 (3.8%) v 233 (22.1%); P<0.001). Consequently, relative 30 day case fatality for weekend versus weekday admissions differed (P<0.001) between correctly coded acute stroke admissions and false positive coding cases. Results were consistent when only the 1327 emergency cases identified by "admission method" from coding were included, with more false positive cases with low case fatality (35 (14.7%)) being included for weekday versus weekend admissions (190 (19.5%) v 48 (13.7%), P<0.02). Among all acute stroke admissions in OXVASC, there was no imbalance in baseline stroke severity for weekends versus weekdays and no difference in case fatality at 30 days (adjusted odds ratio 0.85, 95% confidence interval 0.63 to 1.15; P=0.30) or any adverse "weekend effect" on modified Rankin score at 30 days (0.78, 0.61 to 0.99; P=0.04) or one year (0.76, 0.59 to 0.98; P=0.03) among incident strokes.  Retrospective studies of UK administrative hospital coding data to determine "weekend effects" on outcome in acute medical conditions, such as stroke, can be undermined by inaccurate coding, which can introduce biases that cannot be reliably dealt with by adjustment for case mix. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Effects of digital mammography uptake on downstream breast-related care among older women.

PubMed

Hubbard, Rebecca A; Zhu, Weiwei; Onega, Tracy L; Fishman, Paul; Henderson, Louise M; Tosteson, Anna N A; Buist, Diana S M

2012-12-01

Digital mammography is the dominant modality for breast cancer screening in the United States. No previous studies have investigated as to how introducing digital mammography affects downstream breast-related care. Compare breast-related health care use after a screening mammogram before and after introduction of digital mammography. Longitudinal study of screening mammograms from 14 radiology facilities contributing data to the Breast Cancer Surveillance Consortium performed 1 year before and 4 years after each facility introduced digital mammography, along with linked Medicare claims. We included 30,211 mammograms for women aged 66 years and older without breast cancer. Rates of false-positive recall and short-interval follow-up were based on radiologists' assessments and recommendations; rates of follow-up mammography, ultrasound, and breast biopsy use were based on Medicare claims. False-positive recall rates increased after the introduction of digital mammography. Follow-up mammography use was significantly higher across all 4 years after a facility began using digital mammography compared with the year before [year 1 odds ratio (OR) = 1.7, 95% confidence interval (CI), 1.4-2.1]. Among women with false-positive mammography results, use of ultrasound decreased significantly in the second through fourth years after digital mammography began (year 2 OR = 0.4, 95% CI, 0.3-0.6). Introduction of a new technology led to changes in health care use that persisted for at least 4 years. Comparative effectiveness research on new technologies should consider not only diagnostic performance but also downstream utilization attributable to this apparent learning curve.

The effect of sample storage on the performance and reproducibility of the galactomannan EIA test.

PubMed

Kimpton, George; White, P Lewis; Barnes, Rosemary A

2014-08-01

Galactomannan enzyme immune assay (GM EIA) is a nonculture test for detecting invasive aspergillosis (IA) forming a key part of diagnosis and management. Recent reports have questioned the reproducibility of indices after sample storage. To investigate this, 198 serum samples (72 from cases and 126 from controls) and 61 plasma samples (24 from cases and 37 from controls), initially tested between 2010 and 2013, were retested to determine any change in index. Data were also collected on circulatory protein levels for false-positive serum samples. Serum indices significantly declined on retesting (median: initial, 0.50, retest, 0.23; P < 0.0001). This was shown to be diagnosis dependent as the decline was apparent on retesting of control samples (median: initial 0.50, retest 0.12; P < 0.0001), but was not evident with case samples (median: initial, 0.80, retest, 0.80; P = 0.724). Plasma samples showed little change on reanalysis after long-term storage at 4°C. Retesting after freezing showed a decrease in index values for controls (median: initial 0.40, retest 0.26; P = 0.0505), but no significant change in cases. Circulatory proteins showed a correlation between serum albumin concentration and difference in index value on retesting. Overall, this study suggests that a lack of reproducibility in GM EIA positivity is only significant when disease is absent. Retesting after freezing helps to differentiate false-positive GM EIA results and, with consecutive positivity, could help to improve accuracy in predicting disease status. The freezing of samples prior to testing could potentially reduce false-positivity rates and the need to retest. © The Author 2014. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Evidence for false-positive results for boldenone testing of veal urine due to faecal cross-contamination during sampling.

PubMed

Sgoifo Rossi, C A; Arioli, F; Bassini, A; Chiesa, L M; Dell'Orto, V; Montana, M; Pompa, G

2004-08-01

European Directive 96/22/EC, which controls veterinary residues in animals, does not permit the presence of synthetic growth promoters in products of animal origin or in livestock. Boldenone is categorized in class A3 (growth promoters -- steroids) and is thus a banned substance. Testing of veal urine for banned substances is part of the European Union statutory programme for animals going into the food chain. In relation to this monitoring, three studies were conducted to investigate the apparent presence of the banned growth promoter boldenone in veal urine, which was suspected as being caused by interference from faecal contamination of the sample. In the first study, urine samples were collected at different times (time 0 and after 30 min) using (1) a conventional zoonotechnical apron and (2) a technique designed specifically to avoid faecal contamination ('kettle'). This resulted in samples that were, respectively, positive and negative for the presence of alpha-boldenone (alpha-BOL). In a second study, urine samples negative to alpha-BOL were collected from eight veal calves, but became positive after deliberate faecal contamination. In a third study, data obtained from the Italian RNP (Residual National Program) indicated that 18.1% of 3295 urine samples collected using the zootechnical apron were positive for alpha-BOL and 2.1% for beta-boldenone (beta-BOL), whilst of 902 samples collected using the kettle, beta-BOL was not detected in any samples and only 0.2% were positive to alpha-BOL, in concentrations lower than 2 ng ml(-1). These results further support the supposition that faecal contamination of the urine during sample collection can lead to false-positive results during boldenone analysis.

Avoiding false positives and optimizing identification of true ...

EPA Pesticide Factsheets

The potential for chemicals to affect endocrine signaling is commonly evaluated via in vitro receptor binding and gene activation, but these assays, especially antagonism assays, have potential artifacts that must be addressed for accurate interpretation. Results are presented from screening 94 chemicals from 54 chemical groups for estrogen receptor (ER) activation in a competitive rainbow trout ER (rtER) binding assay and a trout liver slice vitellogenin mRNA expression assay. Results from true competitive agonists and antagonists, and inactive chemicals with little or no indication of ER binding or gene activation were easily interpreted. However, results for numerous industrial chemicals were more challenging to interpret, including chemicals with: (1) apparent competitive binding curves but no gene activation, (2) apparent binding and gene inhibition with evidence of either cytotoxicity or changes in assay media pH, (3) apparent binding but non-competitive gene inhibition of unknown cause, or (4) no rtER binding and gene inhibition not due to competitive ER interaction but due to toxicity, pH change, or some unknown cause. The use of endpoints such as toxicity, pH, precipitate formation, and determination of inhibitor dissociation constants (Ki) for interpreting the results of antagonism and binding assays for diverse chemicals is presented. Of the 94 chemicals tested for antagonism only two, tamoxifen and ICI-182,780, were found to be true competitive

Transient ST segment depression during Holter monitoring: how to avoid false positive findings.

PubMed

Völler, H; Andresen, D; Brüggemann, T; Jereczek, M; Becker, B; Schröder, R

1992-09-01

To increase the specificity of 24-hour Holter monitoring in detecting transient myocardial ischemia, we separated genuine ST deviations from those dependent on artifacts by adding a detailed shape analysis of real-time printouts to the usual criteria of significant ST segment depression. We screened 116 apparently healthy subjects; 31 had to be excluded, because of pathologic findings in preliminary examinations. The remaining 85 (49 women and 36 men; mean age, 43.1 years) underwent Holter monitoring for assessment of the extent, frequency, and duration of episodes of horizontal and descending ST segment depression of at least 0.1 mV that persisted for at least 60 msec after the J point and that were at least 1 minute apart. On the basis of these criteria, six subjects (7.1%) showed 24 episodes of horizontal or descending ST segment depression with a mean of 0.2 mV (range, 0.15 to 0.25 mV), a frequency of four episodes per 24 hours (one to nine), and a duration of 12.2 minutes (range 3-range 41 minutes). Supplementary criteria--e.g., sudden onset of ST segment depression, identical orientation of PQ and ST segments, or simultaneous increase in R and P wave amplitude--made it possible to identify ST changes caused by artifacts in four volunteers. In only two subjects (2.4%) could true silent ischemia not be differentiated from false positive results. Thus consideration of only the extent, frequency, and duration of episodes does not permit a differentiation between true silent ischemia and false positive results. A supplementary shape analysis increases the specificity of ST segment analysis in detecting transient myocardial ischemia during 24-hour Holter monitoring.

A single mutation at the catalytic site of TF1-alpha3beta3gamma complex switches the kinetics of ATP hydrolysis from negative to positive cooperativity.

PubMed

Muneyuki, E; Odaka, M; Yoshida, M

1997-08-11

Previously, we reported the substitution of Tyr341 of the F1-ATPase beta subunit from a thermophilic Bacillus strain PS3 with leucine, cysteine, or alanine (M. Odaka et al. J. Biochem., 115 (1994) 789-796). These mutations resulted in a great decrease in the affinity of the isolated beta subunit for ATP-Mg and an increase in the apparent Km of the alpha3beta3gamma complex in ATP hydrolysis when examined above 0.1 mM ATP. Here, we examined the ATPase activity of the mutant complexes in a wide range of ATP concentration and found that the mutants exhibited apparent positive cooperativity in ATP hydrolysis. This is the first clear demonstration that a single mutation in the catalytic sites converts the kinetics from apparent negative cooperativity in the wild-type alpha3beta3gamma complex to apparent positive cooperativity. The conversion of apparent cooperativity could be explained in terms of a simple kinetic scheme based on the binding change model proposed by Boyer.

Apparent mass of the human body in the vertical direction: Effect of a footrest and a steering wheel

NASA Astrophysics Data System (ADS)

Toward, M. G. R.; Griffin, M. J.

2010-04-01

The apparent mass of the seated human body influences the vibration transmitted through a car seat. The apparent mass of the body is known to be influenced by sitting posture but the influence of the position of the hands and the feet is not well understood. This study was designed to quantify the influence of steering wheel location and the position of a footrest on the vertical apparent mass of the human body. The influences of the forces applied by the hands to a steering wheel and by the feet to a footrest were also investigated. Twelve subjects were exposed to whole-body vertical random vibration (1.0 m s -2 rms over the frequency range 0.13-40.0 Hz) while supported by a rigid seat with a backrest reclined to 15°. The apparent mass of the body was measured with five horizontal positions and three vertical positions of a steering wheel and also with hands in the lap, and with five horizontal positions of a footrest. The influence of five forward forces (0, 50, 100, 150, 200 N) applied separately to the 'steering wheel' and the footrest were also investigated as well as a 'no backrest' condition. With their hands in their laps, subjects exhibited a resonance around 6.7 Hz, compared to 4.8 Hz when sitting upright with no backrest. In the same posture holding a steering wheel, the mass supported on the seat surface decreased and there was an additional resonance at 4 Hz. Moving the steering wheel away from the body reduced the apparent mass at the primary resonance frequency and increased the apparent mass around the 4 Hz resonance. As the feet moved forward, the mass supported on the seat surface decreased, indicating that the backrest and footrest supported a greater proportion of the subject weight. Applying force to either the steering wheel or the footrest reduced the apparent mass at resonance and decreased the mass supported on the seat surface. It is concluded that the positions and contact conditions of the hands and the feet affect the biodynamic response of the body in a car driving posture. As the biodynamic response influences the vibration transmitted through seats, these factors should be considered in dynamic models of vehicle seating.

Cost Analysis of Cot-Side Screening Methods for Neonatal Hypoglycaemia.

PubMed

Glasgow, Matthew J; Harding, Jane E; Edlin, Richard

2018-06-12

Babies at risk of neonatal hypoglycaemia are often screened using cot-side glucometers, but non-enzymatic glucometers are inaccurate, potentially resulting in over-treatment and under-treatment, and low values require laboratory confirmation. More accurate enzymatic glucometers are available but at apparently higher costs. Our objective was to compare the cost of screening for neonatal hypoglycaemia using point-of-care enzymatic and non-enzymatic glucometers. We used a decision tree to model costs, including consumables and staff time. Sensitivity analyses assessed the impact of staff time, staff costs, probability that low results are confirmed via laboratory testing, false-positive and false-negative rates of non-enzymatic glucometers, and the blood glucose concentration threshold. In the primary analysis, screening using an enzymatic glucometer cost NZD 86.94 (USD 63.47) while using a non-enzymatic glucometer cost NZD 97.08 (USD 70.87) per baby. Sensitivity analyses showed that using an enzymatic glucometer is cost saving with wide variations in staff time and costs, irrespective of the false-positive level of non-enzymatic glucometers, and where ≥78% of low values are laboratory confirmed. Where non-enzymatic glucometers may be less costly (e.g., false-negative rate exceeds 15%), instances of hypoglycaemia will be missed. Reducing the blood glucose concentration threshold to 1.94 mmol/L reduced the incidence of hypoglycaemia from 52 to 13%, and the cost of screening using a non-enzymatic glucometer to NZD 47.71 (USD 34.83). In view of their lower cost in most circumstances and greater accuracy, enzymatic glucometers should be routinely utilised for point-of-care screening for neonatal hypoglycaemia. © 2018 S. Karger AG, Basel.

Emergency ultrasound in the acute assessment of haemothorax

PubMed Central

Brooks, A; Davies, B; Smethhurst, M; Connolly, J

2004-01-01

Aims: To evaluate thoracic ultrasound for the detection of haemothorax in patients with thoracic trauma against established investigations. Methods: Thoracic ultrasound was performed as an extension of the standard focused assessment with sonography for trauma (FAST) protocol used at the Queen's Medical Centre for the assessment of adult patients with torso trauma. Fluid was sought in both pleural cavities using a hand portable ultrasound system by one of two non-radiologists trained in FAST. Findings were compared against subsequent investigations/procedures performed at the discretion of the attending emergency physician—supine chest radiography, intercostal drain, computed tomography, or thoracotomy. The sensitivity of the technique and the time taken to diagnosis for each investigation were recorded. Results: Sixty one patients, 54 (89%) after blunt trauma, underwent thoracic ultrasound evaluation during the study. Twelve patients had a haemothorax detected by ultrasound and confirmed by computed tomography or by tube thoracostomy. Four haemothoraces detected on ultrasound were not apparent on trauma chest radiography. There were 12 true positives, 48 true negatives, no false positives, and one false negative scan. The sensitivity of ultrasound was 92% and specificity 100% with a positive predictive value of 100% and negative predictive value 98% for the detection of haemothorax after trauma. Conclusions: Emergency ultrasound of the chest performed as part of the primary survey of the traumatised patient can rapidly and accurately diagnose haemothorax and is a valuable tool to augment the immediate clinical assessment of these patients. PMID:14734374

Contemporary Trends in Land Surface Phenologies from the Aral Basin Suggest Weather- or Irrigation-Driven Changes in GPP not Land Cover Change

NASA Astrophysics Data System (ADS)

Wright, C. K.; de Beurs, K.; Henebry, G. M.

2009-12-01

The transformation of the Aral Sea into the Aral Lakes is a startling example of anthropogenic environmental degradation. However, ongoing impacts of hydrologic modification and climatic change are occurring throughout the nearly 2 million km2 Aral Basin (AB), thus requiring synoptic, basin-wide monitoring of environmental trends. The MODIS 500m global land cover (LC) product is a potential source of such information in a data-sparse region like the AB. However, we find that it is particularly unstable in this arid/semi-arid region. For example, 25% of AB pixels change LC class between 2001 and 2005 versions of the global LC using the IGBP LC scheme. Here we present an alternate analysis of environmental trends in the AB using MODIS data at the same spatial resolution, but incorporating temporal information embedded within contemporary land surface phenologies (LSPs), in contrast to temporally delimited LC. NDVI time series from 2001-2008 were derived from 500m MODIS NBAR data (16-d composites every 8 d; MCD43A4). Focusing on the period from 1 March to 1 October, each pixel time series was comprised of 27 NDVI values per year (or 216 composites in total). Trend analysis using the nonparametric Seasonal Kendall test revealed a number of spatially coherent hotspots of highly significant (p<0.01) positive and negative trends in NDVI dynamics over the 2001-2008 interval. Relative to the 2001 and 2005 LC classifications, positive trends tended to coincide with the following transitions between IGBP classes: open shrub → closed shrub; grassland → {open shrub, cropland}; {open shrub, cropland/natural vegetation mix} → cropland. These findings suggest that apparent LC change events might be false-positives caused by weather-driven increases in GPP. In turn, negative trends were largely coincident with putative LC change to grassland from mostly woody classes: {closed shrub, open shrub, woody savanna, savanna, snow/ice, barren} → grassland. Here, potential false-positives may reflect effects of regional drought on woody classes, declining mountain snowpack, or original misclassification of grassland as barren, i.e., we would expect declining NDVI in drought-affected grassland, with limited sensitivity to NDVI trends in the barren class. In the intensively irrigated subregion of Karakalpakstan, the MODIS LC product indicates an elevated rate of change from natural vegetation to cropland and vice versa. These transitions tend to coincide with highly significant (p<0.01) negative or positive NDVI trends. However, visual inspection of 2001 and 2005 Landsat imagery from Karakalpakstan did not indicate extensive LC change. Here we interpret apparent false-positives in the global LC product as arising from localized changes in irrigation or cropping practices. Overall, this work demonstrates the utility of temporally dense LSPs for large-area monitoring of environmental change, as opposed to occasional LC classifications which, in arid regions like the AB, may exhibit instability and sensitivity with respect to a region’s normal range of interannual spectral variability.

Fertility and apparent genetic anticipation in Lynch syndrome.

PubMed

Stupart, Douglas; Win, Aung Ko; Jenkins, Mark; Winship, Ingrid M; Goldberg, Paul; Ramesar, Rajkumar

2014-09-01

Genetic anticipation is the phenomenon in which age of onset of an inherited disorder decreases in successive generations. Inconsistent evidence suggests that this occurs in Lynch syndrome. A possible cause for apparent anticipation is fecundity bias, which occurs if the disease adversely affects fertility. The purpose of this study was to determine the effect of age of diagnosis of colorectal cancer (CRC) on lifetime fertility in Lynch syndrome, and whether this can falsely create the appearance of genetic anticipation. A computer model simulated age of diagnosis of CRC in hypothetical Lynch syndrome carriers and their offspring. The model assumed similar age distribution of CRC across generations (i.e. that there was no true anticipation). Age distribution of CRC diagnosis, and lifetime fertility rates (grouped by age of diagnosis of CRC) were determined from the Australasian Colorectal Cancer Family Registry (ACCFR). Apparent anticipation was calculated by comparing ages of diagnosis of CRC in affected parent-child pairs. A total of 1,088 patients with CRC were identified from the ACCFR. Total lifetime (cohort) fertility was related to age of diagnosis of CRC (correlation coefficient 0.13, P = 0.0001). In the simulation, apparent anticipation was 1.8 ± 0.54 years (P = 0.0044). Observed apparent anticipation in the ACCFR cohort was 4.8 ± 1.73 years (P = 0.0064). There was no difference in apparent anticipation between the simulate d and observed parent-child pairs (P = 0.89). The appearance of genetic anticipation in Lynch syndrome can be falsely created due to changes in fertility.

Serodiagnosis of infectious mononucleosis with a bovine erythrocyte glycoprotein.

PubMed

Fletcher, M A; Klimas, N G; Latif, Z A; Caldwell, K E

1983-09-01

A glycoprotein from bovine erythrocyte membrane was evaluated in two immunoassays as a reagent for the serodiagnosis of infectious mononucleosis (IM). We previously reported that a partially purified preparation of this glycoprotein, when attached to latex beads, agglutinated in the presence of IM heterophile antibody. In the present study, we used a highly purified form of the glycoprotein both as an agglutinating reagent, covalently bound to latex, and in a solid-phase sandwich-type radioimmunoassay (RIA) for IM antibody detection in a larger population of patients. We tested serum samples from college students with symptoms suggestive of IM with the latex reagent (143 samples) and with the RIA (245 samples). Correlation of these two tests, both with each other and with the classical differentially absorbed, agglutination tests for Paul-Bunnell antibody in IM sera, using fresh sheep or horse cells, was excellent (greater than 97% agreement). The new tests also corresponded in most cases with a rapid, unabsorbed preserved horse erythrocyte slide test. However, in this study of 245 samples, both apparent false-positives (5 samples) and apparent false-negatives (3 samples) were observed with this slide test. In conclusion, we found that the bovine glycoprotein as a reagent can facilitate the diagnosis of IM, giving results comparable to those with erythrocyte agglutination tests on differentially absorbed sera. The advantages are ease and speed of performance (latex test), potential for automation (RIA test), stability and uniformity of the glycoprotein reagent (latex and RIA tests), and most importantly, the ability to use unabsorbed sera (latex and RIA tests).

Origin of the flax cultivar 'Appar' and its position within the Linum perenne complex

Treesearch

Rosemary L. Pendleton; Stanley G. Kitchen; Joann Mudge; E. Durant McArthur

2008-01-01

The 'Appar' flax germplasm was originally released by the USDA Soil Conservation Service as a cultivar of Linum lewisii. The observation that 'Appar' is heterostylic, a key taxonomic character distinguishing Lewis flax from other members of the Linum perenne complex, created a need for further study in order to...

E/N effects on K0 values revealed by high precision measurements under low field conditions

NASA Astrophysics Data System (ADS)

Hauck, Brian C.; Siems, William F.; Harden, Charles S.; McHugh, Vincent M.; Hill, Herbert H.

2016-07-01

Ion mobility spectrometry (IMS) is used to detect chemical warfare agents, explosives, and narcotics. While IMS has a low rate of false positives, their occurrence causes the loss of time and money as the alarm is verified. Because numerous variables affect the reduced mobility (K0) of an ion, wide detection windows are required in order to ensure a low false negative response rate. Wide detection windows, however, reduce response selectivity, and interferents with similar K0 values may be mistaken for targeted compounds and trigger a false positive alarm. Detection windows could be narrowed if reference K0 values were accurately known for specific instrumental conditions. Unfortunately, there is a lack of confidence in the literature values due to discrepancies in the reported K0 values and their lack of reported error. This creates the need for the accurate control and measurement of each variable affecting ion mobility, as well as for a central accurate IMS database for reference and calibration. A new ion mobility spectrometer has been built that reduces the error of measurements affecting K0 by an order of magnitude less than ±0.2%. Precise measurements of ±0.002 cm2 V-1 s-1 or better have been produced and, as a result, an unexpected relationship between K0 and the electric field to number density ratio (E/N) has been discovered in which the K0 values of ions decreased as a function of E/N along a second degree polynomial trend line towards an apparent asymptote at approximately 4 Td.

Gravitational pressure, apparent horizon and thermodynamics of FLRW universe in the teleparallel gravity

NASA Astrophysics Data System (ADS)

da Rocha-Neto, J. F.; Morais, B. R.

2018-04-01

In the context of the teleparallel equivalent of general relativity the concept of gravitational pressure and gravitational energy-momentum arisen in a natural way. In the case of a Friedmann-Lemaitre-Robertson-Walker space FLRW we obtain the total energy contained inside the apparent horizon and the radial pressure over the apparent horizon area. We use these definitions to written a thermodynamics relation TAdSA = dEA+PAdVA at the apparent horizon, where EA is the total energy inside the apparent horizon, VA is the areal volume of the apparent horizon, PA is the radial pressure over the apparent horizon area, SA is the entropy which can be assumed as one quarter of the apparent horizon area only for a non stationary apparent horizon. We identify TA as the temperature at the surface of the apparent horizon. We shown that for all expanding accelerated FLRW model of universe the radial pressure is positive.

A three-year follow-up of congenital adrenal hyperplasia newborn screening.

PubMed

Pezzuti, Isabela L; Barra, Cristina B; Mantovani, Rafael M; Januário, José N; Silva, Ivani N

2014-01-01

congenital adrenal hyperplasia (CAH) newborn screening can prevent neonatal mortality in children with the salt-wasting form of the disease and prevent incorrect gender assignments, which can occur in females. However, the occurrence of false-positive results in preterm or low-birth-weight newborns creates some diagnostic difficulties, with consequent therapeutic implications. This study aimed to report the results of a pilot project for neonatal CAH screening conducted in the state of Minas Gerais, Brazil from 09/2007 to 05/2008 with a three-year follow-up. dried blood specimens were collected on filter paper cards three to seven days after birth of all newborns in the period. Samples were analyzed for 17-hydroxyprogesterone using an enzyme-linked immunosorbent assay (ELISA). a total of 159,415 children were screened. The apparent incidence of the classic variant of the disease was 1:9,963, based on initial diagnoses following newborn screening. During the follow-up period, eight of 16 children initially diagnosed with CAH were reclassified as unaffected, resulting in a revised incidence of 1:19,927. The false-positive rate was 0.31%, and the positive predictive value was 2.1%. Sensitivity and specificity were 100% and 99.7%, respectively. newborn screening is an important public health policy in developing countries such as Brazil, where CAH remains underdiagnosed. It has great potential to identify children with the disease who otherwise cannot be diagnosed earlier. Long-term follow-up and monitoring of all children with positive screening results are crucial to ensure a correct diagnosis and to calculate a reliable incidence ratio of the disease. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

ctDNA Determination of EGFR Mutation Status in European and Japanese Patients with Advanced NSCLC: The ASSESS Study.

PubMed

Reck, Martin; Hagiwara, Koichi; Han, Baohui; Tjulandin, Sergei; Grohé, Christian; Yokoi, Takashi; Morabito, Alessandro; Novello, Silvia; Arriola, Edurne; Molinier, Olivier; McCormack, Rose; Ratcliffe, Marianne; Normanno, Nicola

2016-10-01

To offer patients with EGFR mutation-positive advanced NSCLC appropriate EGFR tyrosine kinase inhibitor treatment, mutation testing of tumor samples is required. However, tissue/cytologic samples are not always available or evaluable. The large, noninterventional diagnostic ASSESS study (NCT01785888) evaluated the utility of circulating free tumor-derived DNA (ctDNA) from plasma for EGFR mutation testing. ASSESS was conducted in 56 centers (in Europe and Japan). Eligible patients (with newly diagnosed locally advanced/metastatic treatment-naive advanced NSCLC) provided diagnostic tissue/cytologic and plasma samples. DNA extracted from tissue/cytologic samples was subjected to EGFR mutation testing using local practices; designated laboratories performed DNA extraction/mutation testing of blood samples. The primary end point was level of concordance of EGFR mutation status between matched tissue/cytologic and plasma samples. Of 1311 patients enrolled, 1288 were eligible. Concordance of mutation status in 1162 matched samples was 89% (sensitivity 46%, specificity 97%, positive predictive value 78%, and negative predictive value 90%). A group of 25 patients with apparent false-positive plasma results was overrepresented for cytologic samples, use of less sensitive tissue testing methodologies, and smoking habits associated with high EGFR mutation frequency, indicative of false-negative tumor results. In cases in which plasma and tumor samples were tested with identical highly sensitive methods, positive predictive value/sensitivity were generally improved. These real-world data suggest that ctDNA is a feasible sample for EGFR mutation analysis. It is important to conduct mutation testing of both tumor and plasma samples in specialized laboratories, using robust/sensitive methods to ensure that patients receive appropriate treatments that target the molecular features of their disease. Copyright © 2016 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

First day of life pulse oximetry screening to detect congenital heart defects.

PubMed

Meberg, Alf; Brügmann-Pieper, Sabine; Due, Reidar; Eskedal, Leif; Fagerli, Ingebjørg; Farstad, Teresa; Frøisland, Dag Helge; Sannes, Catharina Hovland; Johansen, Ole Jakob; Keljalic, Jasmina; Markestad, Trond; Nygaard, Egil Andre; Røsvik, Alet; Silberg, Inger Elisabeth

2008-06-01

To evaluate the efficacy of first day of life pulse oximetry screening to detect congenital heart defects (CHDs). We performed a population-based prospective multicenter study of postductal (foot) arterial oxygen saturation (SpO(2)) in apparently healthy newborns after transfer from the delivery suite to the nursery. SpO(2) < 95% led to further diagnostic evaluations. Of 57,959 live births, 50,008 (86%) were screened. In the screened population, 35 CHDs were [corrected] classified as critical (ductus dependent, cyanotic). CHDs were prospectively registered and diagnosed in 658/57,959 (1.1%) [corrected] Of the infants screened, 324 (0.6%) failed the test. Of these, 43 (13%) had CHDs (27 critical), and 134 (41%) had pulmonary diseases or other disorders. The remaining 147 infants (45%) were healthy with transitional circulation. The median age for babies with CHDs at failing the test was 6 hours (range, 1-21 hours). For identifying critical CHDs, the pulse oximetry screening had a sensitivity rate of 77.1% (95% CI, 59.4-89.0), specificity rate of 99.4% (95% CI, 99.3-99.5), and a false-positive rate of 0.6% (95% CI, 0.5-0.7). Early pulse oximetry screening promotes early detection of critical CHDs and other potentially severe diseases. The sensitivity rate for detecting critical CHDs is high, and the false-positive rate is low.

False Position, Double False Position and Cramer's Rule

ERIC Educational Resources Information Center

Boman, Eugene

2009-01-01

We state and prove the methods of False Position (Regula Falsa) and Double False Position (Regula Duorum Falsorum). The history of both is traced from ancient Egypt and China through the work of Fibonacci, ending with a connection between Double False Position and Cramer's Rule.

Advantages of bioconjugated silica-coated nanoparticles as an innovative diagnosis for human toxoplasmosis.

PubMed

Aly, Ibrahim; Taher, Eman E; El Nain, Gehan; El Sayed, Hoda; Mohammed, Faten A; Hamad, Rabab S; Bayoumy, Elsayed M

2018-01-01

Nanotechnology is a promising arena for generating new applications in Medicine. To successfully functionalised nanoparticles for a given biomedical application, a wide range of chemical, physical and biological factors have to be taken into account. Silica-coated nanoparticles, (SiO2NP) exhibit substantial diagnostic activity owing to their large surface to volume ratios and crystallographic surface structure. This work aimed to evaluate the advantage of bioconjugation of SiO2NP with PAb against Toxoplasma lyzate antigen (TLA) as an innovative diagnostic method for human toxoplasmosis. This cross-sectional study included 120 individuals, divided into Group I: 70 patients suspected for Toxoplasma gondii based on the presence of clinical manifestation. Group II: 30 patients harboring other parasites than T. gondii Group III: 20 apparently healthy individuals free from toxoplasmosis and other parasitic infections served as negative control. Detection of circulating Toxoplasma antigen was performed by Sandwich ELISA and Nano-sandwich ELISA on sera and pooled urine of human samples. Using Sandwich ELISA, 10 out of 70 suspected Toxoplasma-infected human serum samples showed false negative and 8 out of 30 of other parasites groups were false positive giving 85.7% sensitivity and 84.0% specificity, while the sensitivity and specificity were 78.6% and 70% respectively in urine samples. Using Nano-Sandwich ELISA, 7 out of 70 suspected Toxoplasma-infected human samples showed false negative results and the sensitivity of the assay was 90.0%, while 4 out of 30 of other parasites groups were false positive giving 92.0% specificity, while the sensitivity and specificity were 82.6% and 80% respectively in urine samples. In conclusion, our data demonstrated that loading SiO2 nanoparticles with pAb increased the sensitivity and specificity of Nano-sandwich ELISA for detection of T.gondii antigens in serum and urine samples, thus active (early) and light infections could be easily detected. Copyright © 2017 Elsevier B.V. All rights reserved.

Owner assessment of pruritus and gastrointestinal signs in apparently healthy dogs with no history of cutaneous or noncutaneous disease.

PubMed

Stetina, Kacie M; Marks, Stanley L; Griffin, Craig E

2015-08-01

Determining the cause of pruritus relies on establishing the pattern of abnormal pruritus. The presence of gastrointestinal (GI) disease has also been helpful in determining the cause of pruritus. No study has systematically evaluated typical GI signs and pruritic behaviours in apparently healthy dogs. To evaluate owners' perceptions of pruritus and GI signs in apparently healthy dogs, and determine if age, breed, activity, diet or supplements affected these signs. Three hundred and fourteen apparently healthy dogs ≥ 12 months old with an unremarkable physical examination and no history of pruritus, otitis, skin/hair disease, metabolic or GI disease were enrolled. Thirty one veterinarians enrolled dogs after establishing their pruritus visual analog scale (PVAS) score and faecal consistency score (FCS); owners completed a comprehensive online survey regarding GI signs, possible pruritic behaviours, ear cleaning and sneezing. A PVAS score of ≤ 1.9 was recorded in 87.6% of dogs and the FCS was 2-3 in 94.9% of dogs. PVAS was positively correlated with paw licking/chewing, facial/muzzle rubbing, head shaking and sneezing. Scooting was positively correlated with sneezing. Over 96% of dogs had 1-3 bowel movements (BM) per day. Age was positively correlated with facial/muzzle rubbing, sneezing, coprophagia and borborygmi. The number of walks/day was positively correlated with paw licking/chewing, head shaking, sneezing, number of BM/day, coprophagia, belching, flatulence and borborygmi. A standard method of asking relevant questions was developed and the frequency of GI signs and many behaviours that may indicate pruritus in apparently healthy dogs was established. © 2015 ESVD and ACVD.

Prevalence of antibodies to bluetongue virus and Anaplasma marginale in Montana yearling in Montana yearling cattle entering Alberta feedlots: Fall 2001

PubMed Central

2004-01-01

Abstract A serologic survey was conducted in yearling cattle imported into Alberta feedlots from Montana during October 2001 to estimate the prevalence of antibodies to bluetongue virus (BTV) and Anaplasma marginale in Montana yearling cattle. The apparent prevalence of antibodies to BTV when the competitive enzyme-linked immunosorbent assay (cELISA) was used was 0.37% (21/5608). Test positive cELISA samples were also all positive when tested by virus neutralization (VN) and they reacted to 1 or more BTV serotypes, including 2, 10, 11, 13, and 17. The apparent prevalence of antibodies to A. marginale when a recombinant cELISA (rcELISA) was used with a positive cutoff at 30% inhibition was 1.93% (108/5608). When the rcELISA positive cutoff was at 42% inhibition, the apparent prevalence was 0.73% (41/5608). After the reported sensitivity and specificity of the test had been accounted for, the A. marginale antibody results were consistent with a population that was either free of exposure or had a very low prevalence for A. marginale. PMID:15283518

A Comparison of Variant Calling Pipelines Using Genome in a Bottle as a Reference

PubMed Central

2015-01-01

High-throughput sequencing, especially of exomes, is a popular diagnostic tool, but it is difficult to determine which tools are the best at analyzing this data. In this study, we use the NIST Genome in a Bottle results as a novel resource for validation of our exome analysis pipeline. We use six different aligners and five different variant callers to determine which pipeline, of the 30 total, performs the best on a human exome that was used to help generate the list of variants detected by the Genome in a Bottle Consortium. Of these 30 pipelines, we found that Novoalign in conjunction with GATK UnifiedGenotyper exhibited the highest sensitivity while maintaining a low number of false positives for SNVs. However, it is apparent that indels are still difficult for any pipeline to handle with none of the tools achieving an average sensitivity higher than 33% or a Positive Predictive Value (PPV) higher than 53%. Lastly, as expected, it was found that aligners can play as vital a role in variant detection as variant callers themselves. PMID:26539496

Comparison of Lateral Flow Assay, Kidney Inhibition Swab, and Liquid Chromatography-Tandem Mass Spectrometry for the Detection of Penicillin G Residues in Sow Urine.

PubMed

Shelver, Weilin L; Chakrabarty, Shubhashis; Smith, David J

2017-03-01

Sows (n = 126) were administered penicillin G; urine, collected at slaughter, was screened by kidney inhibition swab (KIS; 4 h testing time) and then stored at -80 °C (∼1200 days) until analysis by lateral flow assay (LF, ∼5 min testing time) and tandem quadrupole LC-MS/MS (TQ) analysis. The stability of penicillin in urine during storage was verified using TQ analyses. Quantitative results were well-correlated (R 2 = 0.98) with only a ∼10% decrease in penicillin concentration during the 3-year storage period. KIS retesting of stored samples returned results consistent with the original analyses. Lateral flow assay results were highly correlated with the KIS and TQ results. A KIS positive sample, which was not confirmed by TQ or LF, was assayed by Triple-TOF LC-MS to determine the cause of the apparent false positive. This study suggests LF can be used to quickly and efficiently screen for penicillin G residues before slaughter.

Occupancy models for data with false positive and false negative errors and heterogeneity across sites and surveys

Treesearch

Paige F.B. Ferguson; Michael J. Conroy; Jeffrey Hepinstall-Cymerman; Nigel Yoccoz

2015-01-01

False positive detections, such as species misidentifications, occur in ecological data, although many models do not account for them. Consequently, these models are expected to generate biased inference.The main challenge in an analysis of data with false positives is to distinguish false positive and false negative...

Manganese dioxide causes spurious gold values in flame atomic-absorption readings from HBr-Br2 digestions

USGS Publications Warehouse

Campbell, W.L.

1981-01-01

False readings, apparently caused by the presence of high concentrations of manganese dioxide, have been observed in our current flame atomic-absorption procedure for the determination of gold. After a hydrobromic acid (HBr)-bromine (Br2) leach, simply heating the sample to boiling to remove excess Br2 prior to extraction with methyl-isobutyl-ketone (MIBK) eliminates these false readings. ?? 1981.

Amodal representation of occluded surfaces: role of invisible stimuli in apparent motion correspondence.

PubMed

Shimojo, S; Nakayama, K

1990-01-01

A series of demonstrations were created where the perceived depth of targets was controlled by stereoscopic disparity. A closer object (a cloud) was made to jump back and forth horizontally, partially occluding a farther object (a full moon). The more distant moon appeared stationary even though the unoccluded portion of it, a crescent, changed position. Reversal of the relative depth of the moon and cloud gave a totally different percept: the crescent appeared to flip back and forth in the front depth plane. Thus, the otherwise-robust apparent motion of the moon crescents was completely abolished in the cloud-closer case alone. This motion-blocking effect is attributed to the 'amodal presence' of the occluded surface continuing behind the occluding surface. To measure the effect of this occluded 'invisible' surface quantitatively, a bistable apparent motion display was used (Ramachandran and Anstis 1983a): two small rectangular-shaped targets changed their positions back and forth between two frames, and the disparity of a large centrally positioned rectangle was varied. When the perceived depths supported the possibility of amodal completion behind the large rectangle, increased vertical motion of the targets was found, suggesting that the amodal presence of the targets behind the occluder had effectively changed the center position of the moving targets for purposes of motion correspondence. Amodal contours are literally 'invisible', yet it is hypothesized that they have a neural representation at sufficiently early stages of visual processing to alter the correspondence solving process for apparent motion.

Improving computer-aided detection assistance in breast cancer screening by removal of obviously false-positive findings.

PubMed

Mordang, Jan-Jurre; Gubern-Mérida, Albert; Bria, Alessandro; Tortorella, Francesco; den Heeten, Gerard; Karssemeijer, Nico

2017-04-01

Computer-aided detection (CADe) systems for mammography screening still mark many false positives. This can cause radiologists to lose confidence in CADe, especially when many false positives are obviously not suspicious to them. In this study, we focus on obvious false positives generated by microcalcification detection algorithms. We aim at reducing the number of obvious false-positive findings by adding an additional step in the detection method. In this step, a multiclass machine learning method is implemented in which dedicated classifiers learn to recognize the patterns of obvious false-positive subtypes that occur most frequently. The method is compared to a conventional two-class approach, where all false-positive subtypes are grouped together in one class, and to the baseline CADe system without the new false-positive removal step. The methods are evaluated on an independent dataset containing 1,542 screening examinations of which 80 examinations contain malignant microcalcifications. Analysis showed that the multiclass approach yielded a significantly higher sensitivity compared to the other two methods (P < 0.0002). At one obvious false positive per 100 images, the baseline CADe system detected 61% of the malignant examinations, while the systems with the two-class and multiclass false-positive reduction step detected 73% and 83%, respectively. Our study showed that by adding the proposed method to a CADe system, the number of obvious false positives can decrease significantly (P < 0.0002). © 2017 American Association of Physicists in Medicine.

Statistical approaches to account for false-positive errors in environmental DNA samples.

PubMed

Lahoz-Monfort, José J; Guillera-Arroita, Gurutzeta; Tingley, Reid

2016-05-01

Environmental DNA (eDNA) sampling is prone to both false-positive and false-negative errors. We review statistical methods to account for such errors in the analysis of eDNA data and use simulations to compare the performance of different modelling approaches. Our simulations illustrate that even low false-positive rates can produce biased estimates of occupancy and detectability. We further show that removing or classifying single PCR detections in an ad hoc manner under the suspicion that such records represent false positives, as sometimes advocated in the eDNA literature, also results in biased estimation of occupancy, detectability and false-positive rates. We advocate alternative approaches to account for false-positive errors that rely on prior information, or the collection of ancillary detection data at a subset of sites using a sampling method that is not prone to false-positive errors. We illustrate the advantages of these approaches over ad hoc classifications of detections and provide practical advice and code for fitting these models in maximum likelihood and Bayesian frameworks. Given the severe bias induced by false-negative and false-positive errors, the methods presented here should be more routinely adopted in eDNA studies. © 2015 John Wiley & Sons Ltd.

Easy fix for clinical laboratories for the false-positive defect with the Abbott AxSym total beta-hCG test.

PubMed

Cole, Laurence A; Khanlian, Sarah A

2004-05-01

False-positive hCG results can lead to erroneous diagnoses and needless chemotherapy and surgery. In the last 2 years, eight publications described cases involving false-positive hCG tests; all eight involved the AxSym test. We investigated the source of this abundance of cases and a simple fix that may be used by clinical laboratories. False-positive hCG was primarily identified by absence of hCG in urine and varying or negative hCG results in alternative tests. Seventeen false-positive serum samples in the AxSym test were evaluated undiluted and at twofold dilution with diluent containing excess goat serum or immunoglobulin. We identified 58 patients with false-positive hCG, 47 of 58 due to the Abbott AxSym total hCGbeta test (81%). Sixteen of 17 of these "false-positive" results (mean 100 mIU/ml) became undetectable when tested again after twofold dilution. A simple twofold dilution with this diluent containing excess goat serum or immunoglobulin completely protected 16 of 17 samples from patients having false-positive results. It is recommended that laboratories using this test use twofold dilution as a minimum to prevent false-positive results.

CT Colonography with Computer-aided Detection: Recognizing the Causes of False-Positive Reader Results

PubMed Central

Dachman, Abraham H.; Wroblewski, Kristen; Vannier, Michael W.; Horne, John M.

2014-01-01

Computed tomography (CT) colonography is a screening modality used to detect colonic polyps before they progress to colorectal cancer. Computer-aided detection (CAD) is designed to decrease errors of detection by finding and displaying polyp candidates for evaluation by the reader. CT colonography CAD false-positive results are common and have numerous causes. The relative frequency of CAD false-positive results and their effect on reader performance on the basis of a 19-reader, 100-case trial shows that the vast majority of CAD false-positive results were dismissed by readers. Many CAD false-positive results are easily disregarded, including those that result from coarse mucosa, reconstruction, peristalsis, motion, streak artifacts, diverticulum, rectal tubes, and lipomas. CAD false-positive results caused by haustral folds, extracolonic candidates, diminutive lesions (<6 mm), anal papillae, internal hemorrhoids, varices, extrinsic compression, and flexural pseudotumors are almost always recognized and disregarded. The ileocecal valve and tagged stool are common sources of CAD false-positive results associated with reader false-positive results. Nondismissable CAD soft-tissue polyp candidates larger than 6 mm are another common cause of reader false-positive results that may lead to further evaluation with follow-up CT colonography or optical colonoscopy. Strategies for correctly evaluating CAD polyp candidates are important to avoid pitfalls from common sources of CAD false-positive results. ©RSNA, 2014 PMID:25384290

A Closer Look at Self-Reported Suicide Attempts: False Positives and False Negatives

ERIC Educational Resources Information Center

Ploderl, Martin; Kralovec, Karl; Yazdi, Kurosch; Fartacek, Reinhold

2011-01-01

The validity of self-reported suicide attempt information is undermined by false positives (e.g., incidences without intent to die), or by unreported suicide attempts, referred to as false negatives. In a sample of 1,385 Austrian adults, we explored the occurrence of false positives and false negatives with detailed, probing questions. Removing…

Role of Rhinovirus C in Apparently Life-Threatening Events in Infants, Spain

PubMed Central

García, M. Luz; Pozo, Francisco; Reyes, Noelia; Pérez-Breña, Pilar; Casas, Inmaculada

2009-01-01

To assess whether infants hospitalized after an apparently life-threatening event had an associated respiratory virus infection, we analyzed nasopharyngeal aspirates from 16 patients. Nine of 11 infants with positive virus results were infected by rhinoviruses. We detected the new genogroup of rhinovirus C in 6 aspirates. PMID:19788827

"False Positive" Claims of Near-Death Experiences and "False Negative" Denials of Near-Death Experiences

ERIC Educational Resources Information Center

Greyson, Bruce

2005-01-01

Some persons who claim to have had near-death experiences (NDEs) fail research criteria for having had NDEs ("false positives"); others who deny having had NDEs do meet research criteria for having had NDEs ("false negatives"). The author evaluated false positive claims and false negative denials in an organization that promotes near-death…

Evaluation of ADCP apparent bed load velocity in a large sand-bed river: Moving versus stationary boat conditions

USGS Publications Warehouse

Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

2011-01-01

Detailed mapping of bathymetry and apparent bed load velocity using a boat-mounted acoustic Doppler current profiler (ADCP) was carried out along a 388-m section of the lower Missouri River near Columbia, Missouri. Sampling transects (moving boat) were completed at 5- and 20-m spacing along the study section. Stationary (fixed-boat) measurements were made by maintaining constant boat position over a target point where the position of the boat did not deviate more than 3 m in any direction. For each transect and stationary measurement, apparent bed load velocity (vb) was estimated using ADCP bottom tracking data and high precision real-time kinematic (RTK) global positioning system (GPS). The principal objectives of this research are to (1) determine whether boat motion introduces a bias in apparent bed load velocity measurements; and (2) evaluate the reliability of ADCP bed velocity measurements for a range of sediment transport environments. Results indicate that both high transport (vb>0.6 m/s) and moving-boat conditions (for both high and low transport environments) increase the relative variability in estimates of mean bed velocity. Despite this, the spatially dense single-transect measurements were capable of producing detailed bed velocity maps that correspond closely with the expected pattern of sediment transport over large dunes. ?? 2011 American Society of Civil Engineers.

Optical drift effects in general relativity

NASA Astrophysics Data System (ADS)

Korzyński, Mikołaj; Kopiński, Jarosław

2018-03-01

We consider the question of determining the optical drift effects in general relativity, i.e. the rate of change of the apparent position, redshift, Jacobi matrix, angular distance and luminosity distance of a distant object as registered by an observer in an arbitrary spacetime. We present a fully relativistic and covariant approach, in which the problem is reduced to a hierarchy of ODE's solved along the line of sight. The 4-velocities and 4-accelerations of the observer and the emitter and the geometry of the spacetime along the line of sight constitute the input data. We build on the standard relativistic geometric optics formalism and extend it to include the time derivatives of the observables. In the process we obtain two general, non-perturbative relations: the first one between the gravitational lensing, represented by the Jacobi matrix, and the apparent position drift, also called the cosmic parallax, and the second one between the apparent position drift and the redshift drift. The applications of the results include the theoretical study of the drift effects of cosmological origin (so-called real-time cosmology) in numerical or exact Universe models.

Risk of breast cancer after false-positive results in mammographic screening.

PubMed

Román, Marta; Castells, Xavier; Hofvind, Solveig; von Euler-Chelpin, My

2016-06-01

Women with false-positive results are commonly referred back to routine screening. Questions remain regarding their long-term outcome of breast cancer. We assessed the risk of screen-detected breast cancer in women with false-positive results. We conducted a joint analysis using individual level data from the population-based screening programs in Copenhagen and Funen in Denmark, Norway, and Spain. Overall, 150,383 screened women from Denmark (1991-2008), 612,138 from Norway (1996-2010), and 1,172,572 from Spain (1990-2006) were included. Poisson regression was used to estimate the relative risk (RR) of screen-detected cancer for women with false-positive versus negative results. We analyzed information from 1,935,093 women 50-69 years who underwent 6,094,515 screening exams. During an average 5.8 years of follow-up, 230,609 (11.9%) women received a false-positive result and 27,849 (1.4%) were diagnosed with screen-detected cancer. The adjusted RR of screen-detected cancer after a false-positive result was 2.01 (95% CI: 1.93-2.09). Women who tested false-positive at first screen had a RR of 1.86 (95% CI: 1.77-1.96), whereas those who tested false-positive at third screening had a RR of 2.42 (95% CI: 2.21-2.64). The RR of breast cancer at the screening test after the false-positive result was 3.95 (95% CI: 3.71-4.21), whereas it decreased to 1.25 (95% CI: 1.17-1.34) three or more screens after the false-positive result. Women with false-positive results had a twofold risk of screen-detected breast cancer compared to women with negative tests. The risk remained significantly higher three or more screens after the false-positive result. The increased risk should be considered when discussing stratified screening strategies. © 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

US women's attitudes to false positive mammography results and detection of ductal carcinoma in situ: cross sectional survey

PubMed Central

Schwartz, Lisa M; Woloshin, Steven; Sox, Harold C; Fischhoff, Baruch; Welch, H Gilbert

2000-01-01

Objective To determine women's attitudes to and knowledge of both false positive mammography results and the detection of ductal carcinoma in situ after screening mammography. Design Cross sectional survey. Setting United States. Participants 479 women aged 18-97 years who did not report a history of breast cancer. Main outcome measures Attitudes to and knowledge of false positive results and the detection of ductal carcinoma in situ after screening mammography. Results Women were aware that false positive results do occur. Their median estimate of the false positive rate for 10 years of annual screening was 20% (25th percentile estimate, 10%; 75th percentile estimate, 45%). The women were highly tolerant of false positives: 63% thought that 500 or more false positives per life saved was reasonable and 37% would tolerate 10 000 or more. Women who had had a false positive result (n=76) expressed the same high tolerance: 39% would tolerate 10 000 or more false positives. 62% of women did not want to take false positive results into account when deciding about screening. Only 8% of women thought that mammography could harm a woman without breast cancer, and 94% doubted the possibility of non-progressive breast cancers. Few had heard about ductal carcinoma in situ, a cancer that may not progress, but when informed, 60% of women wanted to take into account the possibility of it being detected when deciding about screening. Conclusions Women are aware of false positives and seem to view them as an acceptable consequence of screening mammography. In contrast, most women are unaware that screening can detect cancers that may never progress but feel that such information would be relevant. Education should perhaps focus less on false positives and more on the less familiar outcome of detection of ductal carcinoma in situ. PMID:10856064

False Paradoxes of Superposition in Electric and Acoustic Waves.

ERIC Educational Resources Information Center

Levine, Richard C.

1980-01-01

Corrected are several misconceptions concerning the apparently "missing" energy that results when acoustic or electromagnetic waves cancel by destructive interference and the wave impedance reflected to the sources of the wave energy changes so that the input power is reduced. (Author/CS)

Reliable nanomaterial classification of powders using the volume-specific surface area method

NASA Astrophysics Data System (ADS)

Wohlleben, Wendel; Mielke, Johannes; Bianchin, Alvise; Ghanem, Antoine; Freiberger, Harald; Rauscher, Hubert; Gemeinert, Marion; Hodoroaba, Vasile-Dan

2017-02-01

The volume-specific surface area (VSSA) of a particulate material is one of two apparently very different metrics recommended by the European Commission for a definition of "nanomaterial" for regulatory purposes: specifically, the VSSA metric may classify nanomaterials and non-nanomaterials differently than the median size in number metrics, depending on the chemical composition, size, polydispersity, shape, porosity, and aggregation of the particles in the powder. Here we evaluate the extent of agreement between classification by electron microscopy (EM) and classification by VSSA on a large set of diverse particulate substances that represent all the anticipated challenges except mixtures of different substances. EM and VSSA are determined in multiple labs to assess also the level of reproducibility. Based on the results obtained on highly characterized benchmark materials from the NanoDefine EU FP7 project, we derive a tiered screening strategy for the purpose of implementing the definition of nanomaterials. We finally apply the screening strategy to further industrial materials, which were classified correctly and left only borderline cases for EM. On platelet-shaped nanomaterials, VSSA is essential to prevent false-negative classification by EM. On porous materials, approaches involving extended adsorption isotherms prevent false positive classification by VSSA. We find no false negatives by VSSA, neither in Tier 1 nor in Tier 2, despite real-world industrial polydispersity and diverse composition, shape, and coatings. The VSSA screening strategy is recommended for inclusion in a technical guidance for the implementation of the definition.

Misconceptions of Mexican Teachers in the Solution of Simple Pendulum

ERIC Educational Resources Information Center

Garcia Trujillo, Luis Antonio; Ramirez Díaz, Mario H.; Rodriguez Castillo, Mario

2013-01-01

Solving the position of a simple pendulum at any time is apparently one of the most simple and basic problems to solve in high school and college physics courses. However, because of this apparent simplicity, teachers and physics texts often assume that the solution is immediate without pausing to reflect on the problem formulation or verifying…

Ignorance and Translation, "Artifacts" for Practices of Equality

ERIC Educational Resources Information Center

Derycke, Marc

2010-01-01

The passion of inequality exists in the discourse that binds people by their adhesion to the beliefs about the hierarchic distribution of positions in society. In this manner the differences that structure the (apparently) natural titles to be governed or to govern are put in a state of aggregation. The apparent naturalness of these titles masks a…

Experimental investigation of false positive errors in auditory species occurrence surveys

USGS Publications Warehouse

Miller, David A.W.; Weir, Linda A.; McClintock, Brett T.; Grant, Evan H. Campbell; Bailey, Larissa L.; Simons, Theodore R.

2012-01-01

False positive errors are a significant component of many ecological data sets, which in combination with false negative errors, can lead to severe biases in conclusions about ecological systems. We present results of a field experiment where observers recorded observations for known combinations of electronically broadcast calling anurans under conditions mimicking field surveys to determine species occurrence. Our objectives were to characterize false positive error probabilities for auditory methods based on a large number of observers, to determine if targeted instruction could be used to reduce false positive error rates, and to establish useful predictors of among-observer and among-species differences in error rates. We recruited 31 observers, ranging in abilities from novice to expert, that recorded detections for 12 species during 180 calling trials (66,960 total observations). All observers made multiple false positive errors and on average 8.1% of recorded detections in the experiment were false positive errors. Additional instruction had only minor effects on error rates. After instruction, false positive error probabilities decreased by 16% for treatment individuals compared to controls with broad confidence interval overlap of 0 (95% CI: -46 to 30%). This coincided with an increase in false negative errors due to the treatment (26%; -3 to 61%). Differences among observers in false positive and in false negative error rates were best predicted by scores from an online test and a self-assessment of observer ability completed prior to the field experiment. In contrast, years of experience conducting call surveys was a weak predictor of error rates. False positive errors were also more common for species that were played more frequently, but were not related to the dominant spectral frequency of the call. Our results corroborate other work that demonstrates false positives are a significant component of species occurrence data collected by auditory methods. Instructing observers to only report detections they are completely certain are correct is not sufficient to eliminate errors. As a result, analytical methods that account for false positive errors will be needed, and independent testing of observer ability is a useful predictor for among-observer variation in observation error rates.

Characterisation of false-positive observations in botanical surveys

PubMed Central

2017-01-01

Errors in botanical surveying are a common problem. The presence of a species is easily overlooked, leading to false-absences; while misidentifications and other mistakes lead to false-positive observations. While it is common knowledge that these errors occur, there are few data that can be used to quantify and describe these errors. Here we characterise false-positive errors for a controlled set of surveys conducted as part of a field identification test of botanical skill. Surveys were conducted at sites with a verified list of vascular plant species. The candidates were asked to list all the species they could identify in a defined botanically rich area. They were told beforehand that their final score would be the sum of the correct species they listed, but false-positive errors counted against their overall grade. The number of errors varied considerably between people, some people create a high proportion of false-positive errors, but these are scattered across all skill levels. Therefore, a person’s ability to correctly identify a large number of species is not a safeguard against the generation of false-positive errors. There was no phylogenetic pattern to falsely observed species; however, rare species are more likely to be false-positive as are species from species rich genera. Raising the threshold for the acceptance of an observation reduced false-positive observations dramatically, but at the expense of more false negative errors. False-positive errors are higher in field surveying of plants than many people may appreciate. Greater stringency is required before accepting species as present at a site, particularly for rare species. Combining multiple surveys resolves the problem, but requires a considerable increase in effort to achieve the same sensitivity as a single survey. Therefore, other methods should be used to raise the threshold for the acceptance of a species. For example, digital data input systems that can verify, feedback and inform the user are likely to reduce false-positive errors significantly. PMID:28533972

Kepler Certified False Positive Table

NASA Technical Reports Server (NTRS)

Bryson, Stephen T.; Batalha, Natalie Marie; Colon, Knicole Dawn; Coughlin, Jeffrey Langer; Haas, Michael R.; Henze, Chris; Huber, Daniel; Morton, Tim; Rowe, Jason Frank; Mullally, Susan Elizabeth;

Cumulative risk of false positive test in relation to breast symptoms in mammography screening: a historical prospective cohort study.

PubMed

Singh, Deependra; Pitkäniemi, Janne; Malila, Nea; Anttila, Ahti

2016-09-01

Mammography has been found effective as the primary screening test for breast cancer. We estimated the cumulative probability of false positive screening test results with respect to symptom history reported at screen. A historical prospective cohort study was done using individual screening data from 413,611 women aged 50-69 years with 2,627,256 invitations for mammography screening between 1992 and 2012 in Finland. Symptoms (lump, retraction, and secretion) were reported at 56,805 visits, and 48,873 visits resulted in a false positive mammography result. Generalized linear models were used to estimate the probability of at least one false positive test and true positive at screening visits. The estimates were compared among women with and without symptoms history. The estimated cumulative probabilities were 18 and 6 % for false positive and true positive results, respectively. In women with a history of a lump, the cumulative probabilities of false positive test and true positive were 45 and 16 %, respectively, compared to 17 and 5 % with no reported lump. In women with a history of any given symptom, the cumulative probabilities of false positive test and true positive were 38 and 13 %, respectively. Likewise, women with a history of a 'lump and retraction' had the cumulative false positive probability of 56 %. The study showed higher cumulative risk of false positive tests and more cancers detected in women who reported symptoms compared to women who did not report symptoms at screen. The risk varies substantially, depending on symptom types and characteristics. Information on breast symptoms influences the balance of absolute benefits and harms of screening.

Multislice CT Angiography in Renal Artery Stent Evaluation: Prospective Comparison with Intra-Arterial Digital Subtraction Angiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raza, Syed A.; Chughtai, Aamer R.; Wahba, Mona

2004-01-15

Purpose: To assess the role of multislice computed tomography angiography (MCTA) in the evaluation of renal artery stents, using intra-arterial digital subtraction angiography (DSA) as the gold standard. Methods: Twenty consecutive patients (15 men, 5 women) with 23 renal artery stents prospectively underwent both MCTA and DSA. Axial images, multiplanar reconstructions and maximum intensity projection images were used for diagnosis. The MCTA and DSA images were each interpreted without reference to the result of the other investigation. Results:The three cases of restenosis on DSA were detected correctly by MCTA; in 19 cases where MCTA showed a fully patent stent, themore » DSA was also negative. Sensitivity and negative predictive value (NPV) of MCTA were therefore 100%. In four cases, MCTA showed apparently minimal disease which was not shown on DSA. These cases are taken as false positive giving a specificity of 80% and a positive predictive value of 43%. Conclusion: The high sensitivity and NPV suggest MCTA may be useful as a noninvasive screen for renal artery stentrestenosis. MCTA detected mild disease in a few patients which was not confirmed on angiography.« less

[Occurrence of AmpC-positive Klebsiella pneumoniae strains in patients with haematological malignancies].

PubMed

Chromá, Magdaléna; Kolár, Milan; Sauer, Pavel; Faber, Edgar; Stosová, Tatána; Koukalová, Dagmar; Indrák, Karel

2008-10-01

Currently, important bacterial beta-lactamases of increasing clinical significance include AmpC enzymes. The aim was to assess their occurrence in Klebsiella pneumoniae strains isolated from patients with haematological malignancies in a prospective study. Over a 2-month period, strains of the species were isolated from clinical material obtained from patients hospitalized at the Department of Haemato-Oncology of the University Hospital Olomouc. The strains were identified using standard microbiological techniques and the Vitek 2 automated system. Production of AmpC beta-lactamases was roughly determined by phenotypic tests and subsequently confirmed by PCR detection of genes encoding these enzymes. During the above-mentioned period, a total of 35 K. pneumoniae isolates were collected. In 7 of them, production of AmpC beta-lactamases was preliminarily detected by phenotypic test. The multiplex PCR method confirmed phenotyping and determined DHA types in all the isolates. All AmpC-positive isolates were false-susceptible to at least one of the tested third-generation cephalosporins. In one patient, clinically apparent infection caused by this strain was documented. The reported results suggest the possibility of occurrence of AmpC-beta-lactamases in K. pneumoniae strains with clinical significance.

Detecting false positives in multielement designs: implications for brief assessments.

PubMed

Bartlett, Sara M; Rapp, John T; Henrickson, Marissa L

2011-11-01

The authors assessed the extent to which multielement designs produced false positives using continuous duration recording (CDR) and interval recording with 10-s and 1-min interval sizes. Specifically, they created 6,000 graphs with multielement designs that varied in the number of data paths, and the number of data points per data path, using a random number generator. In Experiment 1, the authors visually analyzed the graphs for the occurrence of false positives. Results indicated that graphs depicting only two sessions for each condition (e.g., a control condition plotted with multiple test conditions) produced the highest percentage of false positives for CDR and interval recording with 10-s and 1-min intervals. Conversely, graphs with four or five sessions for each condition produced the lowest percentage of false positives for each method. In Experiment 2, they applied two new rules, which were intended to decrease false positives, to each graph that depicted a false positive in Experiment 1. Results showed that application of new rules decreased false positives to less than 5% for all of the graphs except for those with two data paths and two data points per data path. Implications for brief assessments are discussed.

Response time as a discriminator between true- and false-positive responses in suprathreshold perimetry.

PubMed

Artes, Paul H; McLeod, David; Henson, David B

2002-01-01

To report on differences between the latency distributions of responses to stimuli and to false-positive catch trials in suprathreshold perimetry. To describe an algorithm for defining response time windows and to report on its performance in discriminating between true- and false-positive responses on the basis of response time (RT). A sample of 435 largely inexperienced patients underwent suprathreshold visual field examination on a perimeter that was modified to record RTs. Data were analyzed from 60,500 responses to suprathreshold stimuli and from 523 false-positive responses to catch trials. False-positive responses had much more variable latencies than responses to suprathreshold stimuli. An algorithm defining RT windows on the basis of z-transformed individual latency samples correctly identified more than 70% of false-positive responses to catch trials, whereas fewer than 3% of responses to suprathreshold stimuli were classified as false-positive responses. Latency analysis can be used to detect a substantial proportion of false-positive responses in suprathreshold perimetry. Rejection of such responses may increase the reliability of visual field screening by reducing variability and bias in a small but clinically important proportion of patients.

Comparison of the accuracy rates of 3-T and 1.5-T MRI of the knee in the diagnosis of meniscal tear.

PubMed

Grossman, Jeffrey W; De Smet, Arthur A; Shinki, Kazuhiko

2009-08-01

The purpose of this study was to compare the accuracy of 3-T MRI with that of 1.5-T MRI of the knee in the diagnosis of meniscal tear and to analyze the causes of diagnostic error. We reviewed the medical records and original MRI interpretations of 100 consecutive patients who underwent 3-T MRI of the knee and of 100 consecutive patients who underwent 1.5-T MRI of the knee to determine the accuracy of diagnoses of meniscal tear. Knee arthroscopy was the reference standard. We retrospectively reviewed all MRI diagnostic errors to determine the cause of the errors. At arthroscopy, 109 medial and 77 lateral meniscal tears were identified in the 200 patients. With two abnormal MR images indicating a meniscal tear, the sensitivity and specificity for medial tear were 92.7% and 82.2% at 1.5-T MRI and 92.6% and 76.1% at 3-T MRI (p = 1.0, p = 0.61). The sensitivity and specificity for lateral tears were 68.4% and 95.2% at 1.5-T MRI and 69.2% and 91.8% at 3-T MRI (p = 1.0, p = 0.49). Of the false-positive diagnoses of medial meniscal tear, five of eight at 1.5 T and seven of 11 at 3 T were apparent peripheral longitudinal tears of the posterior horn. Fifteen of the 26 missed medial and lateral meniscal tears were not seen in retrospect even with knowledge of the tear type and location. Allowing for sample size limitations, we found comparable accuracy of 3-T and 1.5-T MRI of the knee in the diagnosis of meniscal tear. The causes of false-positive and false-negative MRI diagnoses of meniscal tear are similar for 3-T and 1.5-T MRI.

A method of immediate detection of objects with a near-zero apparent motion in series of CCD-frames

NASA Astrophysics Data System (ADS)

Savanevych, V. E.; Khlamov, S. V.; Vavilova, I. B.; Briukhovetskyi, A. B.; Pohorelov, A. V.; Mkrtichian, D. E.; Kudak, V. I.; Pakuliak, L. K.; Dikov, E. N.; Melnik, R. G.; Vlasenko, V. P.; Reichart, D. E.

2018-01-01

The paper deals with a computational method for detection of the solar system minor bodies (SSOs), whose inter-frame shifts in series of CCD-frames during the observation are commensurate with the errors in measuring their positions. These objects have velocities of apparent motion between CCD-frames not exceeding three rms errors (3σ) of measurements of their positions. About 15% of objects have a near-zero apparent motion in CCD-frames, including the objects beyond the Jupiter's orbit as well as the asteroids heading straight to the Earth. The proposed method for detection of the object's near-zero apparent motion in series of CCD-frames is based on the Fisher f-criterion instead of using the traditional decision rules that are based on the maximum likelihood criterion. We analyzed the quality indicators of detection of the object's near-zero apparent motion applying statistical and in situ modeling techniques in terms of the conditional probability of the true detection of objects with a near-zero apparent motion. The efficiency of method being implemented as a plugin for the Collection Light Technology (CoLiTec) software for automated asteroids and comets detection has been demonstrated. Among the objects discovered with this plugin, there was the sungrazing comet C/2012 S1 (ISON). Within 26 min of the observation, the comet's image has been moved by three pixels in a series of four CCD-frames (the velocity of its apparent motion at the moment of discovery was equal to 0.8 pixels per CCD-frame; the image size on the frame was about five pixels). Next verification in observations of asteroids with a near-zero apparent motion conducted with small telescopes has confirmed an efficiency of the method even in bad conditions (strong backlight from the full Moon). So, we recommend applying the proposed method for series of observations with four or more frames.

Prescription drugs associated with false-positive results when using faecal immunochemical tests for colorectal cancer screening.

PubMed

Ibáñez-Sanz, Gemma; Garcia, Montse; Rodríguez-Moranta, Francisco; Binefa, Gemma; Gómez-Matas, Javier; Domènech, Xènia; Vidal, Carmen; Soriano, Antonio; Moreno, Víctor

2016-10-01

The most common side effect in population screening programmes is a false-positive result which leads to unnecessary risks and costs. To identify factors associated with false-positive results in a colorectal cancer screening programme with the faecal immunochemical test (FIT). Cross-sectional study of 472 participants with a positive FIT who underwent colonoscopy for confirmation of diagnosis between 2013 and 2014. A false-positive result was defined as having a positive FIT (≥20μg haemoglobin per gram of faeces) and follow-up colonoscopy without intermediate/high-risk lesions or cancer. Women showed a two-fold increased likelihood of a false-positive result compared with men (adjusted OR, 2.3; 95%CI, 1.5-3.4), but no female-specific factor was identified. The other variables associated with a false-positive result were successive screening (adjusted OR, 1.5; 95%CI, 1.0-2.2), anal disorders (adjusted OR, 3.1; 95%CI, 2.1-4.5) and the use of proton pump inhibitors (adjusted OR, 1.8; 95%CI, 1.1-2.9). Successive screening and proton pump inhibitor use were associated with FP in men. None of the other drugs were related to a false-positive FIT. Concurrent use of proton pump inhibitors at the time of FIT might increase the likelihood of a false-positive result. Further investigation is needed to determine whether discontinuing them could decrease the false-positive rate. Copyright © 2016 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

False negative rates in Drosophila cell-based RNAi screens: a case study

PubMed Central

2011-01-01

Background High-throughput screening using RNAi is a powerful gene discovery method but is often complicated by false positive and false negative results. Whereas false positive results associated with RNAi reagents has been a matter of extensive study, the issue of false negatives has received less attention. Results We performed a meta-analysis of several genome-wide, cell-based Drosophila RNAi screens, together with a more focused RNAi screen, and conclude that the rate of false negative results is at least 8%. Further, we demonstrate how knowledge of the cell transcriptome can be used to resolve ambiguous results and how the number of false negative results can be reduced by using multiple, independently-tested RNAi reagents per gene. Conclusions RNAi reagents that target the same gene do not always yield consistent results due to false positives and weak or ineffective reagents. False positive results can be partially minimized by filtering with transcriptome data. RNAi libraries with multiple reagents per gene also reduce false positive and false negative outcomes when inconsistent results are disambiguated carefully. PMID:21251254

32 CFR 2001.21 - Original classification.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Original classification. 2001.21 Section 2001.21... Markings § 2001.21 Original classification. (a) Primary markings. At the time of original classification, the following shall be indicated in a manner that is immediately apparent: (1) Classification...

32 CFR 2001.21 - Original classification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 6 2014-07-01 2014-07-01 false Original classification. 2001.21 Section 2001.21... Markings § 2001.21 Original classification. (a) Primary markings. At the time of original classification, the following shall be indicated in a manner that is immediately apparent: (1) Classification...

32 CFR 2001.21 - Original classification.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 6 2012-07-01 2012-07-01 false Original classification. 2001.21 Section 2001.21... Markings § 2001.21 Original classification. (a) Primary markings. At the time of original classification, the following shall be indicated in a manner that is immediately apparent: (1) Classification...

15 CFR 265.4 - Making or giving of false reports.

Code of Federal Regulations, 2010 CFR

2010-01-01

... NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE REGULATIONS GOVERNING TRAFFIC AND CONDUCT REGULATIONS GOVERNING TRAFFIC AND CONDUCT ON THE GROUNDS OF THE NATIONAL INSTITUTE OF STANDARDS... authorized person investigating an accident or apparent violation of law or these regulations. Nothing in...

45 CFR 689.2 - General policies and responsibilities.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 45 Public Welfare 3 2010-10-01 2010-10-01 false General policies and responsibilities. 689.2 Section 689.2 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE... information-gathering and preliminary fact-finding to determine whether an allegation or apparent instance of...

45 CFR 689.2 - General policies and responsibilities.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 3 2014-10-01 2014-10-01 false General policies and responsibilities. 689.2 Section 689.2 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE... information-gathering and preliminary fact-finding to determine whether an allegation or apparent instance of...

45 CFR 689.2 - General policies and responsibilities.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 45 Public Welfare 3 2013-10-01 2013-10-01 false General policies and responsibilities. 689.2 Section 689.2 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE... information-gathering and preliminary fact-finding to determine whether an allegation or apparent instance of...

45 CFR 689.2 - General policies and responsibilities.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 3 2012-10-01 2012-10-01 false General policies and responsibilities. 689.2 Section 689.2 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE... information-gathering and preliminary fact-finding to determine whether an allegation or apparent instance of...

32 CFR 2001.21 - Original classification.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Original classification. 2001.21 Section 2001.21... Markings § 2001.21 Original classification. (a) Primary markings. At the time of original classification, the following shall be indicated in a manner that is immediately apparent: (1) Classification...

[Roaming through methodology. XXXII. False test results].

PubMed

van der Weijden, T; van den Akker, M

2001-05-12

The number of requests for diagnostic tests is rising. This leads to a higher chance of false test results. The false-negative proportion of a test is the proportion of negative test results among the diseased subjects. The false-positive proportion is the proportion of positive test results among the healthy subjects. The calculation of the false-positive proportion is often incorrect. For example, instead of 1 minus the specificity it is calculated as 1 minus the positive predictive value. This can lead to incorrect decision-making with respect to the application of the test. Physicians must apply diagnostic tests in such a way that the risk of false test results is minimal. The patient should be aware that a perfectly conclusive diagnostic test is rare in medical practice, and should more often be informed of the implications of false-positive and false-negative test results.

Biconditional Prominence Correlation

ERIC Educational Resources Information Center

Teeple, David Allan

2009-01-01

This dissertation presents one solution to a problem in phonological typology, which is to explain the apparent cross-linguistic absence of a pattern I call "Strong-Position Neutralization" (or SPN): neutralization of a contrast in a strong position while the same contrast is maintained in the corresponding weak position. This is predicted in a…

[An autopsied case of senile onset frontotemporal lobar degeneration].

PubMed

Iwasaki, Yasushi; Mori, Keiko; Ito, Masumi; Deguchi, Akira; Yoshida, Mari

2011-06-01

A Japanese male with no family history of neurological disease or dementia showed behavioral abnormalities including egocentric and antisocial behavior at the age of 80. Over the next few years, other psychiatric symptoms such as allotriophagy and stereotypical behavior were also observed and his abnormal behavior became a social problem. Neurological examination revealed no apparent motor abnormalities, pyramidal and extrapyramidal signs, or ataxia. Aphasia, including semantic dementia was not apparent. The severity of memory disturbance was relatively milder than his psychiatric symptoms. Daily living activities and conversational ability were relatively maintained until shortly before his death at the age of 86. The clinical diagnosis was Alzheimer disease. Autopsy revealed that the brain weighed 950 g; frontotemporal atrophy with lateral ventricular dilatation was apparent. Neuron loss, gliosis, and tissue rarefaction were recognized in the frontotemporal cortex, subiculum, transentorhinal cortex, amygdala, and insular cortex and were particularly noticeable in the superficial layer of the cortex. Many ubiquitin-positive/TDP-43 positive but tau-negative dystrophic neurites with a few neuronal cytoplasmic inclusions were widely observed. Neuronal cytoplasmic inclusions were also observed in the dentate gyrus of the hippocampus. Although the spinal cord was not investigated, there was no apparent involvement of the motor neuron system. Small numbers of neurofibrillary tangles and senile plaques were observed, corresponding to Braak stage II and CERAD stage B, respectively. Argyrophilic grains, Lewy bodies and Pick bodies were not observed. The patient was pathologically diagnosed with frontotemporal lobar degeneration with ubiquitin-positive/TDP-43-positive inclusions (FTLD-TDP) and without motor neuron disease. No mutation was found in the TDP-43 gene. We considered the psychiatric symptoms and head CT findings of the present patient to be important observations for helping to discriminate between Alzheimer disease or other neurodegenerative diseases with dementia, and FTLD-TDP.

Patient factors associated with non-attendance at colonoscopy after a positive screening faecal occult blood test.

PubMed

Plumb, Andrew A; Ghanouni, Alex; Rainbow, Sandra; Djedovic, Natasha; Marshall, Sarah; Stein, Judith; Taylor, Stuart A; Halligan, Steve; Lyratzopoulos, Georgios; von Wagner, Christian

2017-03-01

Background Screening participants with abnormal faecal occult blood test results who do not attend further testing are at high risk of colorectal cancer, yet little is known about their reasons for non-attendance. Methods We conducted a medical record review of 170 patients from two English Bowel Cancer Screening Programme centres who had abnormal guaiac faecal occult blood test screening tests between November 2011 and April 2013 but did not undergo colonoscopy. Using information from patient records, we coded and categorized reasons for non-attendance. Results Of the 170 patients, 82 were eligible for review, of whom 66 had at least one recorded reason for lack of colonoscopy follow-up. Reasons fell into seven main categories: (i) other commitments, (ii) unwillingness to have the test, (iii) a feeling that the faecal occult blood test result was a false positive, (iv) another health issue taking priority, (v) failing to complete bowel preparation, (vi) practical barriers (e.g. lack of transport), and (vii) having had or planning colonoscopy elsewhere. The most common single reasons were unwillingness to have a colonoscopy and being away. Conclusions We identify a range of apparent reasons for colonoscopy non-attendance after a positive faecal occult blood test screening. Education regarding the interpretation of guaiac faecal occult blood test findings, offer of alternative confirmatory test options, and flexibility in the timing or location of subsequent testing might decrease non-attendance of diagnostic testing following positive faecal occult blood test.

Bayesian microsaccade detection

PubMed Central

Mihali, Andra; van Opheusden, Bas; Ma, Wei Ji

2017-01-01

Microsaccades are high-velocity fixational eye movements, with special roles in perception and cognition. The default microsaccade detection method is to determine when the smoothed eye velocity exceeds a threshold. We have developed a new method, Bayesian microsaccade detection (BMD), which performs inference based on a simple statistical model of eye positions. In this model, a hidden state variable changes between drift and microsaccade states at random times. The eye position is a biased random walk with different velocity distributions for each state. BMD generates samples from the posterior probability distribution over the eye state time series given the eye position time series. Applied to simulated data, BMD recovers the “true” microsaccades with fewer errors than alternative algorithms, especially at high noise. Applied to EyeLink eye tracker data, BMD detects almost all the microsaccades detected by the default method, but also apparent microsaccades embedded in high noise—although these can also be interpreted as false positives. Next we apply the algorithms to data collected with a Dual Purkinje Image eye tracker, whose higher precision justifies defining the inferred microsaccades as ground truth. When we add artificial measurement noise, the inferences of all algorithms degrade; however, at noise levels comparable to EyeLink data, BMD recovers the “true” microsaccades with 54% fewer errors than the default algorithm. Though unsuitable for online detection, BMD has other advantages: It returns probabilities rather than binary judgments, and it can be straightforwardly adapted as the generative model is refined. We make our algorithm available as a software package. PMID:28114483

Unintentional Changes in the Apparent Stiffness of the Multi-Joint Limb

PubMed Central

Zhou, Tao; Zatsiorsky, Vladimir M.; Latash, Mark L.

2015-01-01

We explored the phenomenon of unintentional changes in the apparent stiffness of the human arm produced by transient changes in the external force. The subjects performed a positional task against a constant baseline force and were instructed not to react to changes in the force. A HapticMaster robot produced a smooth force increase (a perturbation) leading to a hand movement, followed by a dwell time. No visible hand drift was observed during the dwell time. After the robot force dropped to its initial baseline value, the hand moved towards the initial position but stopped short of it. Small perturbations were applied at different time intervals along different directions during the dwell time. Arm apparent stiffness distribution in a horizontal plane was approximated with an ellipse. The apparent stiffness magnitude along the main axis of the ellipse showed a non-monotonic increase with dwell time while the apparent stiffness along the minor axis did not change significantly. We interpreted the early part of the changes in the apparent stiffness as due to peripheral muscle properties. The later part is interpreted as caused by a combination of two processes, a drift in the referent hand coordinate due to the hypothesized back-coupling between the referent and actual hand coordinates and an implicit instruction to keep the hand steady when no changes in robot-generated force took place. The data provide support for the idea of back-coupling between the referent and actual body configurations, which may be an important contributor to stability of motor actions. PMID:26169103

Nonmutagenic carcinogens induce intrachromosomal recombination in dividing yeast cells.

PubMed

Schiestl, R H

1993-12-01

A large number of animal and human carcinogens without apparent genotoxic activity exist (nonmutagenic carcinogens) that are difficult or impossible to detect with the currently used short-term tests. Because of the association of carcinogenesis with genome rearrangement, a system selecting for intrachromosomal recombination (DEL recombination) that results in genome rearrangement has been constructed in the yeast Saccharomyces cerevisiae. Because DEL recombination is under different genetic control than interchromosomal recombination and meiotic recombination, it is probably due to a different mechanism. It has been found that DEL recombination is readily inducible by 10 mutagenic carcinogens and 17 nonmutagenic carcinogens that are not detectable (false negatives) with the Ames assay. In addition, three out of four mutagens that do not cause cancer (false positives in the Ames assay) do not induce DEL recombination. DEL recombination is inducible by UV only in dividing cells but not in cells synchronized in the G1 or G2 phase of the cell cycle. Interchromosomal recombination, on the other hand, is inducible in G1 but not in G2. The nonmutagenic carcinogens induce DEL recombination only in actively growing cells, which may give some indication as to their mechanism. Further characterization of the mechanism involved in induction of DEL recombination may contribute to the understanding of the biological activity of nonmutagenic carcinogens.

Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives.

PubMed

Wolf, Max; Kurvers, Ralf H J M; Ward, Ashley J W; Krause, Stefan; Krause, Jens

2013-04-07

In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true- and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications.

Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives

PubMed Central

Wolf, Max; Kurvers, Ralf H. J. M.; Ward, Ashley J. W.; Krause, Stefan; Krause, Jens

2013-01-01

In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true- and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications. PMID:23407830

Categorizing mistaken false positives in regulation of human and environmental health.

PubMed

Hansen, Steffen Foss; Krayer von Krauss, Martin P; Tickner, Joel A

2007-02-01

One of the concerns often voiced by critics of the precautionary principle is that a widespread regulatory application of the principle will lead to a large number of false positives (i.e., over-regulation of minor risks and regulation of nonexisting risks). The present article proposes a general definition of a regulatory false positive, and seeks to identify case studies that can be considered authentic regulatory false positives. Through a comprehensive review of the science policy literature for proclaimed false positives and interviews with authorities on regulation and the precautionary principle we identified 88 cases. Following a detailed analysis of these cases, we found that few of the cases mentioned in the literature can be considered to be authentic false positives. As a result, we have developed a number of different categories for these cases of "mistaken false positives," including: real risks, "The jury is still out," nonregulated proclaimed risks, "Too narrow a definition of risk," and risk-risk tradeoffs. These categories are defined and examples are presented in order to illustrate their key characteristics. On the basis of our analysis, we were able to identify only four cases that could be defined as regulatory false positives in the light of today's knowledge and recognized uncertainty: the Southern Corn Leaf Blight, the Swine Flu, Saccharin, and Food Irradiation in relation to consumer health. We conclude that concerns about false positives do not represent a reasonable argument against future application of the precautionary principle.

Aspergillus antigen testing in bone marrow transplant recipients

PubMed Central

Williamson, E; Oliver, D; Johnson, E; Foot, A; Marks, D; Warnock, D

2000-01-01

Aims—To assess the clinical usefulness of a commercial aspergillus antigen enzyme linked immunosorbent assay (ELISA) in the diagnosis of invasive aspergillosis (IA) in bone marrow transplant recipients, and to compare it with a commercial latex agglutination (LA) test. Methods—In total, 2026 serum samples from 104 bone marrow transplant recipients were tested. These comprised 67 sera from seven patients who had died with confirmed IA, 268 sera from nine patients who had died with suspected IA, and 1691 sera from 88 patients with no clinical, radiological, or microbiological signs of IA. Results—The ELISA was more sensitive than the LA test. All patients who were ELISA positive were also LA positive, and a positive LA result never preceded a positive ELISA. Twelve of 16 patients with confirmed or suspected IA were ELISA positive on two or more occasions, compared with 10 of 15 who were LA positive. ELISA was positive before LA in five patients (range, 2–14 days), and became positive on the same day in the remainder. Aspergillus antigen was detected by ELISA a median of 15 days before death (range, 4–233). Clinical and/or radiological evidence of IA was noted in all patients, and a positive ELISA was never the sole criterion for introduction of antifungal treatment. Two samples (one from each of two patients without IA) gave false positive results. Conclusions—The aspergillus ELISA is a specific indicator of invasive aspergillosis if the criterion of two positive samples is required to confirm the diagnosis. However, the test is insufficiently sensitive to diagnose aspergillosis before other symptoms or signs are apparent, and hence is unlikely to lead to earlier initiation of antifungal treatment. It is therefore unsuitable for screening of asymptomatic patients at risk of invasive aspergillosis, but does have a useful role in confirming the diagnosis in symptomatic patients. Key Words: invasive aspergillosis • aspergillus antigen • Platelia enzyme linked immunosorbent assay PMID:10889818

An analysis of false positive reactions occurring with the Captia Syph G EIA.

PubMed Central

Ross, J; Moyes, A; Young, H; McMillan, A

1991-01-01

AIM--The Captia Syph G enzyme immuno assay (EAI) offers the potential for the rapid automated detection of syphilis antibodies. This study was designed to assess the role of other sexually transmitted diseases (STDs) in producing false positive reactions in the Captia Syph G EIA. The role of rheumatoid factor (RF) as a potential source of false positives was also analysed. METHODS--Patients who attended a genitourinary medicine (GUM) department and gave a false positive reaction with the EIA between 1988 and 1990 were compared with women undergoing antenatal testing and with the control clinic population (EIA negative) over the same time period. The incidence of sexually transmitted disease (STD) in the clinic population and the false positive reactors was measured in relation to gonorrhoea, chlamydia, genital warts, candidiasis, "other conditions not requiring treatment" and "other conditions requiring treatment." Male: female sex ratios were also compared. Ninety two RF positive sera were analysed with the EIA. RESULTS--The rate of false positive reactions did not differ with respect to the diagnosis within the GUM clinic population. The antenatal group of women, however, had a lower incidence of false positive reactions than the GUM clinic group. No RF positive sera were positive on Captia Syph G EIA testing. CONCLUSIONS--There is no cross reaction between Captia Syph G EIA and any specific STD or with RF positive sera. The lower incidence of false positive reactions in antenatal women is unexplained but may be related to physiological changes associated with pregnancy. PMID:1743715

50 CFR 635.53 - Reports.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Reports. 635.53 Section 635.53 Wildlife..., DEPARTMENT OF COMMERCE ATLANTIC HIGHLY MIGRATORY SPECIES International Port Inspection § 635.53 Reports. (a) Apparent violations shall be reported by the authorized officer on a standardized ICCAT form or form...

9 CFR 351.15 - Reports of violations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Reports of violations. 351.15 Section... INSPECTION AND CERTIFICATION CERTIFICATION OF TECHNICAL ANIMAL FATS FOR EXPORT Facilities and Operations § 351.15 Reports of violations. Inspectors shall report to the circuit supervisor any apparent...

Visual cues for the retrieval of landmark memories by navigating wood ants.

PubMed

Harris, Robert A; Graham, Paul; Collett, Thomas S

2007-01-23

Even on short routes, ants can be guided by multiple visual memories. We investigate here the cues controlling memory retrieval as wood ants approach a one- or two-edged landmark to collect sucrose at a point along its base. In such tasks, ants store the desired retinal position of landmark edges at several points along their route. They guide subsequent trips by retrieving the appropriate memory and moving to bring the edges in the scene toward the stored positions. The apparent width of the landmark turns out to be a powerful cue for retrieving the desired retinal position of a landmark edge. Two other potential cues, the landmark's apparent height and the distance that the ant walks, have little effect on memory retrieval. A simple model encapsulates these conclusions and reproduces the ants' routes in several conditions. According to this model, the ant stores a look-up table. Each entry contains the apparent width of the landmark and the desired retinal position of vertical edges. The currently perceived width provides an index for retrieving the associated stored edge positions. The model accounts for the population behavior of ants and the idiosyncratic training routes of individual ants. Our results imply binding between the edge of a shape and its width and, further, imply that assessing the width of a shape does not depend on the presence of any particular local feature, such as a landmark edge. This property makes the ant's retrieval and guidance system relatively robust to edge occlusions.

Frequency of false positive rapid HIV serologic tests in African men and women receiving PrEP for HIV prevention: implications for programmatic roll-out of biomedical interventions.

PubMed

Ndase, Patrick; Celum, Connie; Kidoguchi, Lara; Ronald, Allan; Fife, Kenneth H; Bukusi, Elizabeth; Donnell, Deborah; Baeten, Jared M

2015-01-01

Rapid HIV assays are the mainstay of HIV testing globally. Delivery of effective biomedical HIV prevention strategies such as antiretroviral pre-exposure prophylaxis (PrEP) requires periodic HIV testing. Because rapid tests have high (>95%) but imperfect specificity, they are expected to generate some false positive results. We assessed the frequency of true and false positive rapid results in the Partners PrEP Study, a randomized, placebo-controlled trial of PrEP. HIV testing was performed monthly using 2 rapid tests done in parallel with HIV enzyme immunoassay (EIA) confirmation following all positive rapid tests. A total of 99,009 monthly HIV tests were performed; 98,743 (99.7%) were dual-rapid HIV negative. Of the 266 visits with ≥1 positive rapid result, 99 (37.2%) had confirmatory positive EIA results (true positives), 155 (58.3%) had negative EIA results (false positives), and 12 (4.5%) had discordant EIA results. In the active PrEP arms, over two-thirds of visits with positive rapid test results were false positive results (69.2%, 110 of 159), although false positive results occurred at <1% (110/65,945) of total visits. When HIV prevalence or incidence is low due to effective HIV prevention interventions, rapid HIV tests result in a high number of false relative to true positive results, although the absolute number of false results will be low. Program roll-out for effective interventions should plan for quality assurance of HIV testing, mechanisms for confirmatory HIV testing, and counseling strategies for persons with positive rapid test results.

Experimental investigation of observation error in anuran call surveys

USGS Publications Warehouse

McClintock, B.T.; Bailey, L.L.; Pollock, K.H.; Simons, T.R.

2010-01-01

Occupancy models that account for imperfect detection are often used to monitor anuran and songbird species occurrence. However, presenceabsence data arising from auditory detections may be more prone to observation error (e.g., false-positive detections) than are sampling approaches utilizing physical captures or sightings of individuals. We conducted realistic, replicated field experiments using a remote broadcasting system to simulate simple anuran call surveys and to investigate potential factors affecting observation error in these studies. Distance, time, ambient noise, and observer abilities were the most important factors explaining false-negative detections. Distance and observer ability were the best overall predictors of false-positive errors, but ambient noise and competing species also affected error rates for some species. False-positive errors made up 5 of all positive detections, with individual observers exhibiting false-positive rates between 0.5 and 14. Previous research suggests false-positive errors of these magnitudes would induce substantial positive biases in standard estimators of species occurrence, and we recommend practices to mitigate for false positives when developing occupancy monitoring protocols that rely on auditory detections. These recommendations include additional observer training, limiting the number of target species, and establishing distance and ambient noise thresholds during surveys. ?? 2010 The Wildlife Society.

Memory for media: investigation of false memories for negatively and positively charged public events.

PubMed

Porter, Stephen; Taylor, Kristian; Ten Brinke, Leanne

2008-01-01

Despite a large body of false memory research, little has addressed the potential influence of an event's emotional content on susceptibility to false recollections. The Paradoxical Negative Emotion (PNE) hypothesis predicts that negative emotion generally facilitates memory but also heightens susceptibility to false memories. Participants were asked whether they could recall 20 "widely publicised" public events (half fictitious) ranging in emotional valence, with or without visual cues. Participants recalled a greater number of true negative events (M=3.31/5) than true positive (M=2.61/5) events. Nearly everyone (95%) came to recall at least one false event (M=2.15 false events recalled). Further, more than twice as many participants recalled any false negative (90%) compared to false positive (41.7%) events. Negative events, in general, were associated with more detailed memories and false negative event memories were more detailed than false positive event memories. Higher dissociation scores were associated with false recollections of negative events, specifically.

Stress and anxiety effects on positive skin test responses in young adults with allergic rhinitis.

PubMed

Heffner, Kathi L; Kiecolt-Glaser, Janice K; Glaser, Ronald; Malarkey, William B; Marshall, Gailen D

2014-07-01

Anxiety and psychological stress affect allergy-related immune function. How these relations influence the evaluations of patients with allergic rhinitis is unknown. To examine whether anxiety and stress exposure affect skin prick test (SPT) responses to common allergens for which patients with atopy showed no prior positive SPT response. Patients with allergic rhinitis, evidenced by clinical history and SPT results, were admitted twice to a hospital research unit for 4 hours. In a crossover design, SPT wheals were assessed before and after the Trier Social Stress Test and then the following morning; for comparison, SPT wheals were assessed before and after a laboratory session without a stressor. Analyses focused on wheal responses for common allergens that tested negative (wheal size <3 mm larger than saline) from SPTs performed at multiple baseline assessments. After the Trier Social Stress Test, more anxious patients with atopy had a higher incidence of positive SPT reactions to antigens that previously tested negative. Anxiety was unrelated to positive SPT incidence under nonstressful conditions. Based on clinical symptom reports, newly positive SPT reactions after the stressor were apparently corrections of previously false-negative SPT reactions. The SPT wheal responses for allergens previously testing negative were enhanced after a stressor. Histamine (positive control) or saline (negative control) SPT responses were not affected. A laboratory stressor affected allergen SPT responses in more anxious patients with allergic rhinitis. In addition to clinical history, assessment of anxiety and current stress at the time of the SPT may provide valuable information about a patient's allergic status and aid in clinical decision making. Copyright © 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

What Do Letter Migration Errors Reveal About Letter Position Coding in Visual Word Recognition?

ERIC Educational Resources Information Center

Davis, Colin J.; Bowers, Jeffrey S.

2004-01-01

Dividing attention across multiple words occasionally results in misidentifications whereby letters apparently migrate between words. Previous studies have found that letter migrations preserve within-word letter position, which has been interpreted as support for position-specific letter coding. To investigate this issue, the authors used word…

Generalized site occupancy models allowing for false positive and false negative errors

USGS Publications Warehouse

Royle, J. Andrew; Link, W.A.

2006-01-01

Site occupancy models have been developed that allow for imperfect species detection or ?false negative? observations. Such models have become widely adopted in surveys of many taxa. The most fundamental assumption underlying these models is that ?false positive? errors are not possible. That is, one cannot detect a species where it does not occur. However, such errors are possible in many sampling situations for a number of reasons, and even low false positive error rates can induce extreme bias in estimates of site occupancy when they are not accounted for. In this paper, we develop a model for site occupancy that allows for both false negative and false positive error rates. This model can be represented as a two-component finite mixture model and can be easily fitted using freely available software. We provide an analysis of avian survey data using the proposed model and present results of a brief simulation study evaluating the performance of the maximum-likelihood estimator and the naive estimator in the presence of false positive errors.

Comparison of 4th-Generation HIV Antigen/Antibody Combination Assay With 3rd-Generation HIV Antibody Assays for the Occurrence of False-Positive and False-Negative Results.

PubMed

Muthukumar, Alagarraju; Alatoom, Adnan; Burns, Susan; Ashmore, Jerry; Kim, Anne; Emerson, Brian; Bannister, Edward; Ansari, M Qasim

2015-01-01

To assess the false-positive and false-negative rates of a 4th-generation human immunodeficiency virus (HIV) assay, the Abbott ARCHITECT, vs 2 HIV 3rd-generation assays, the Siemens Centaur and the Ortho-Clinical Diagnostics Vitros. We examined 123 patient specimens. In the first phase of the study, we compared 99 specimens that had a positive screening result via the 3rd-generation Vitros assay (10 positive, 82 negative, and 7 indeterminate via confirmatory immunofluorescent assay [IFA]/Western blot [WB] testing). In the second phase, we assessed 24 HIV-1 RNA-positive (positive result via the nuclear acid amplification test [NAAT] and negative/indeterminate results via the WB test) specimens harboring acute HIV infection. The 4th-generation ARCHITECT assay yielded fewer false-positive results (n = 2) than the 3rd-generation Centaur (n = 9; P = .02) and Vitros (n = 82; P <.001) assays. One confirmed positive case had a false-negative result via the Centaur assay. When specimens from the 24 patients with acute HIV-1 infection were tested, the ARCHITECT assay yielded fewer false-negative results (n = 5) than the Centaur (n = 10) (P = .13) and the other 3rd-generation tests (n = 16) (P = .002). This study indicates that the 4th-generation ARCHITECT HIV assay yields fewer false-positive and false-negative results than the 3rd-generation HIV assays we tested. Copyright© by the American Society for Clinical Pathology (ASCP).

11 CFR 1.14 - Specific exemptions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... to refer apparent violations of the Act to the Attorney General or other law enforcement authorities... 11 Federal Elections 1 2010-01-01 2010-01-01 false Specific exemptions. 1.14 Section 1.14 Federal Elections FEDERAL ELECTION COMMISSION PRIVACY ACT § 1.14 Specific exemptions. (a) No individual, under the...

42 CFR 51.26 - Conflicts of interest.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Conflicts of interest. 51.26 Section 51.26 Public... Priorities § 51.26 Conflicts of interest. The P&A system must develop appropriate policies and procedures to avoid actual or apparent conflict of interest involving clients, employees, contractors and...

The Values Guiding the Operational Practices of a Suburban Superintendent.

ERIC Educational Resources Information Center

Aplin, Norita D.

Although the role of a superintendent has commonly involved a conflict between instructional leadership and business management, this dichotomy is apparently false; superintendents can effectively fill both roles. To explore this possible harmony of roles, one superintendent was studied who by reputation filled both roles very well. The…

12 CFR 1805.812 - Fraud, waste and abuse.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Fraud, waste and abuse. 1805.812 Section 1805.812 Banks and Banking COMMUNITY DEVELOPMENT FINANCIAL INSTITUTIONS FUND, DEPARTMENT OF THE TREASURY..., waste and abuse. Any person who becomes aware of the existence or apparent existence of fraud, waste or...

False-positive alarms for bacterial screening of platelet concentrates with BacT/ALERT new-generation plastic bottles: a multicenter pilot study.

PubMed

Hundhausen, T; Müller, T H

2005-08-01

The microbial detection system BacT/ALERT (bioMérieux) is widely used to monitor bacterial contamination of platelet concentrates (PCs). Recently, the manufacturer introduced polycarbonate culture bottles and a modified pH-sensitive liquid emulsion sensor as microbial growth indicator. This reconfigured assay was investigated in a routine setting. In each of eight transfusion centers, samples from 500 consecutive PCs were monitored for 1 week. For all PCs with a positive BacT/ALERT signal, retained samples and, if available, original PC containers and concomitant red blood cell concentrates were analyzed independently. Initially BacT/ALERT-positive PCs without bacterial identification in any sample were defined as false-positive. BacT/ALERT-positive PCs with bacteria in the first sample only were called potentially positive. PCs with bacteria in the first sample and the same strain in at least one additional sample were accepted as positive. Five PCs (0.13%) were positive, 9 PCs (0.23%) were potentially positive, and 35 PCs (0.9%) were false-positive. The rate of false-positive BacT/ALERT results varied substantially between centers (<0.2%-3.2%). Tracings from false-positive cultures lacked an exponential increase of the signal during incubation. Most of these false-positives were due to malfunctioning cells in various BacT/ALERT incubation units. Careful assessment of individual tracings of samples with positive signals helps to identify malfunctioning incubation units. Their early shutdown or replacement minimizes the high rate of unrectifiable product rejects attributed to false-positive alarms and avoids unnecessary concern of doctors and patients after conversion to a reconfigured BacT/ALERT assay.

Protein family clustering for structural genomics.

PubMed

Yan, Yongpan; Moult, John

2005-10-28

A major goal of structural genomics is the provision of a structural template for a large fraction of protein domains. The magnitude of this task depends on the number and nature of protein sequence families. With a large number of bacterial genomes now fully sequenced, it is possible to obtain improved estimates of the number and diversity of families in that kingdom. We have used an automated clustering procedure to group all sequences in a set of genomes into protein families. Bench-marking shows the clustering method is sensitive at detecting remote family members, and has a low level of false positives. This comprehensive protein family set has been used to address the following questions. (1) What is the structure coverage for currently known families? (2) How will the number of known apparent families grow as more genomes are sequenced? (3) What is a practical strategy for maximizing structure coverage in future? Our study indicates that approximately 20% of known families with three or more members currently have a representative structure. The study indicates also that the number of apparent protein families will be considerably larger than previously thought: We estimate that, by the criteria of this work, there will be about 250,000 protein families when 1000 microbial genomes have been sequenced. However, the vast majority of these families will be small, and it will be possible to obtain structural templates for 70-80% of protein domains with an achievable number of representative structures, by systematically sampling the larger families.

Is there a positive bias in false recognition? Evidence from confabulating amnesia patients.

PubMed

Alkathiri, Nura H; Morris, Robin G; Kopelman, Michael D

2015-10-01

Although there is some evidence for a positive emotional bias in the content of confabulations in brain damaged patients, findings have been inconsistent. The present study used the semantic-associates procedure to induce false recall and false recognition in order to examine whether a positive bias would be found in confabulating amnesic patients, relative to non-confabulating amnesic patients and healthy controls. Lists of positive, negative and neutral words were presented in order to induce false recall or false recognition of non-presented (but semantically associated) words. The latter were termed 'critical intrusions'. Thirteen confabulating amnesic patients, 13 non-confabulating amnesic patients and 13 healthy controls were investigated. Confabulating patients falsely recognised a higher proportion of positive (but unrelated) words, compared with non-confabulating patients and healthy controls. No differences were found for recall memory. Signal detection analysis, however, indicated that the positive bias for false recognition memory might reflect weaker memory in the confabulating amnesic group. This suggested that amnesia patients with weaker memory are more likely to confabulate and the content of these confabulations are more likely to be positive. Copyright © 2015 Elsevier Ltd. All rights reserved.

Study of false positives in 5-ALA induced photodynamic diagnosis of bladder carcinoma

NASA Astrophysics Data System (ADS)

Draga, Ronald O. P.; Grimbergen, Matthijs C. M.; Kok, Esther T.; Jonges, Trudy G. N.; Bosch, J. L. H. R.

2009-02-01

Photodynamic diagnosis (PDD) is a technique that enhances the detection of tumors during cystoscopy using a photosensitizer which accumulates primarily in cancerous cells and will fluoresce when illuminated by violetblue light. A disadvantage of PDD is the relatively low specificity. In this retrospective study we aimed to identify predictors for false positive findings in PDD. Factors such as gender, age, recent transurethral resection of bladder tumors (TURBT), previous intravesical therapy (IVT) and urinary tract infections (UTIs) were examined for association with the false positive rates in a multivariate analysis. Data of 366 procedures and 200 patients were collected. Patients were instilled with 5-aminolevulinic acid (5-ALA) intravesically and 1253 biopsies were taken from tumors and suspicious lesions. Female gender and TURBT are independent predictors of false positives in PDD. However, previous intravesical therapy with Bacille Calmette-Guérin is also an important predictor of false positives. The false positive rate decreases during the first 9-12 weeks after the latest TURBT and the latest intravesical chemotherapy. Although shortly after IVT and TURBT false positives increase, PDD improves the diagnostic sensitivity and results in more adequate treatment strategies in a significant number of patients.

Nano-Advantage in Enhanced Drug Delivery with Biodegradable Nanoparticles: Contribution of Reduced Clearance

PubMed Central

Kadam, Rajendra S.; Bourne, David W. A.

2012-01-01

The aim of this study was to investigate the contribution of reduced apparent clearance to the enhanced exposure reported for biodegradable nanoparticles after extravascular and intravascular routes of administration. Plasma concentration profiles for drug and nanoparticle formulations after administration by intravenous, intraduodenal, and oral routes were extracted from the literature. Data were fit to pharmacokinetic models using BOOMER. The compartmental pharmacokinetic analysis of literature data for six drugs (camptothecin, 9-nitrocamptothecin, epirubicin, vinpocetine, clozapine, and cyclosporine) showed that the encapsulation of drug molecules in nanoparticles significantly reduced the apparent clearance and prolonged the apparent circulation half-life compared with those for the plain drug. Positively charged nanoparticles assessed in this study had lower apparent clearance, lower elimination rate constant values, and longer apparent circulation half-life than neutral and negatively charged nanoparticles. After oral administration, a reduction in apparent clearance contributed substantially to elevations in plasma drug exposure with nanoparticles. For the drugs and delivery systems examined, the nano-advantage in drug delivery enhancement can be explained, in part, by reduced clearance. PMID:22498894

A comparison of standard inhalers for asthma with and without alcohol as the propellant on the measurement of alcohol in breath.

PubMed

Ignacio-García, José M; Ignacio-García, Juan M; Almenara-Barrios, José; Chocrón-Giraldez, María J; Hita-Iglesias, Carmen

2005-01-01

Because most bronchodilator inhalers contain propellant gases or a small amount of ethanol as a co-solvent, the potential for these products to generate false readings on a evidential breath alcohol instrument was evaluated in 69 volunteers with clinically stable asthma. All subjects underwent a breath test on an infrared breath alcohol analyzer (Alcotest 7110, Dräger, Lübeck, Germany) before the use of the asthma inhaler and 1 and 5 min after inhalation. The effects of antiasthmatic medications delivered by metered dose inhalers (MDIs) with alcohol as a vehicle, alcohol-free MDIs, and dry powder inhalers were assessed in homogeneous groups of four to five patients. All subjects were alcohol-free on the preliminary breath test. One minute after inhalation, negative readings were only observed in 25 (36.2%) of subjects. In 62.3% of patients, apparent alcohol results were considered interferences or unstable readings by the breath-test instrument. One subject showed a final positive breath alcohol level (0.07 mg/L). After the use of dry powder inhalers, valid results without interferences were obtained. However, 89.6% of patients in which bronchodilators were delivered by MDIs (with propellant gases in the aerosol) showed altered partial readings and labeled the final output as "invalid," but tests performed 5 min after the use of inhalers were valid and correct in all cases. MDIs with propellants as a vehicle may cause false positive breath alcohol readings in some patients. These effects are transient and may be prevented by a 5-10-min interval between the use of MDIs and breath alcohol testing.

Examining unusual digit span performance in a population of postsecondary students assessed for academic difficulties.

PubMed

Harrison, Allyson G; Rosenblum, Yoni; Currie, Shannon

2010-09-01

Methods of identifying poor test-related motivation using the Wechsler Adult Intelligence Scale Digit Span subtest are based on identification of performance patterns that are implausible if the test taker is investing full effort. No studies to date, however, have examined the specificity of such measures, particularly when evaluating persons with either known or suspected learning or attention disorders. This study investigated performance of academically challenged students on three measures embedded in the Wechsler Adult Intelligence Scale-III, namely, low Digit Span, high Vocabulary-Digit span (Voc-DS), and low Reliable Digit Span scores. Evaluating subjects believed to be investing full effort in testing, it was found that both Digit Span and Reliable Digit Span had high specificity, although both showed relatively lower sensitivity. In contrast, VOC-DS was especially weak in both sensitivity and specificity, with an apparent false positive rate of 28%. Use of VOC-DS is therefore not appropriate for those with a history of learning or attention problems.

Classification of ion mobility spectra by functional groups using neural networks

NASA Technical Reports Server (NTRS)

Bell, S.; Nazarov, E.; Wang, Y. F.; Eiceman, G. A.

1999-01-01

Neural networks were trained using whole ion mobility spectra from a standardized database of 3137 spectra for 204 chemicals at various concentrations. Performance of the network was measured by the success of classification into ten chemical classes. Eleven stages for evaluation of spectra and of spectral pre-processing were employed and minimums established for response thresholds and spectral purity. After optimization of the database, network, and pre-processing routines, the fraction of successful classifications by functional group was 0.91 throughout a range of concentrations. Network classification relied on a combination of features, including drift times, number of peaks, relative intensities, and other factors apparently including peak shape. The network was opportunistic, exploiting different features within different chemical classes. Application of neural networks in a two-tier design where chemicals were first identified by class and then individually eliminated all but one false positive out of 161 test spectra. These findings establish that ion mobility spectra, even with low resolution instrumentation, contain sufficient detail to permit the development of automated identification systems.

The health system impact of false positive newborn screening results for medium-chain acyl-CoA dehydrogenase deficiency: a cohort study.

PubMed

Karaceper, Maria D; Chakraborty, Pranesh; Coyle, Doug; Wilson, Kumanan; Kronick, Jonathan B; Hawken, Steven; Davies, Christine; Brownell, Marni; Dodds, Linda; Feigenbaum, Annette; Fell, Deshayne B; Grosse, Scott D; Guttmann, Astrid; Laberge, Anne-Marie; Mhanni, Aizeddin; Miller, Fiona A; Mitchell, John J; Nakhla, Meranda; Prasad, Chitra; Rockman-Greenberg, Cheryl; Sparkes, Rebecca; Wilson, Brenda J; Potter, Beth K

2016-02-03

There is no consensus in the literature regarding the impact of false positive newborn screening results on early health care utilization patterns. We evaluated the impact of false positive newborn screening results for medium-chain acyl-CoA dehydrogenase deficiency (MCADD) in a cohort of Ontario infants. The cohort included all children who received newborn screening in Ontario between April 1, 2006 and March 31, 2010. Newborn screening and diagnostic confirmation results were linked to province-wide health care administrative datasets covering physician visits, emergency department visits, and inpatient hospitalizations, to determine health service utilization from April 1, 2006 through March 31, 2012. Incidence rate ratios (IRRs) were used to compare those with false positive results for MCADD to those with negative newborn screening results, stratified by age at service use. We identified 43 infants with a false positive newborn screening result for MCADD during the study period. These infants experienced significantly higher rates of physician visits (IRR: 1.42) and hospitalizations (IRR: 2.32) in the first year of life relative to a screen negative cohort in adjusted analyses. Differences in health services use were not observed after the first year of life. The higher use of some health services among false positive infants during the first year of life may be explained by a psychosocial impact of false positive results on parental perceptions of infant health, and/or by differences in underlying health status. Understanding the impact of false positive newborn screening results can help to inform newborn screening programs in designing support and education for families. This is particularly important as additional disorders are added to expanded screening panels, yielding important clinical benefits for affected children but also a higher frequency of false positive findings.

Accounting for false-positive acoustic detections of bats using occupancy models

USGS Publications Warehouse

Clement, Matthew J.; Rodhouse, Thomas J.; Ormsbee, Patricia C.; Szewczak, Joseph M.; Nichols, James D.

2014-01-01

4. Synthesis and applications. Our results suggest that false positives sufficient to affect inferences may be common in acoustic surveys for bats. We demonstrate an approach that can estimate occupancy, regardless of the false-positive rate, when acoustic surveys are paired with capture surveys. Applications of this approach include monitoring the spread of White-Nose Syndrome, estimating the impact of climate change and informing conservation listing decisions. We calculate a site-specific probability of occupancy, conditional on survey results, which could inform local permitting decisions, such as for wind energy projects. More generally, the magnitude of false positives suggests that false-positive occupancy models can improve accuracy in research and monitoring of bats and provide wildlife managers with more reliable information.

Analysis of false results in a series of 835 fine needle aspirates of breast lesions.

PubMed

Willis, S L; Ramzy, I

1995-01-01

To analyze cases of false diagnoses from a large series to help increase the accuracy of fine needle aspiration of palpable breast lesions. The results of FNA of 835 palpable breast lesions were analyzed to determine the reasons for false positive, false negative and false suspicious diagnoses. Of the 835 aspirates, 174 were reported as positive, 549 as negative and 66 as suspicious or atypical but not diagnostic of malignancy. Forty-six cases were considered unsatisfactory. Tissue was available for comparison in 286 cases. The cytologic diagnoses in these cases were reported as follows: positive, 125 (43.7%); suspicious, 33 (11.5%); atypical, 18 (6.2%); negative, 92 (32%); and unsatisfactory, 18 (6.2%). There was one false positive diagnosis, yielding a false positive rate of 0.8%. This lesion was a case of fibrocystic change with hyperplasia, focal fat necrosis and reparative atypia. There were 14 false negative cases, resulting in a false negative rate of 13.2%. Nearly all these cases were sampling errors and included infiltrating ductal carcinomas (9), ductal carcinomas in situ (2), infiltrating lobular carcinomas (2) and tubular carcinoma (1). Most of the suspicious and atypical lesions proved to be carcinomas (35/50). The remainder were fibroadenomas (6), fibrocystic change (4), gynecomastia (2), adenosis (2) and granulomatous mastitis (1). A positive diagnosis of malignancy by FNA is reliable in establishing the diagnosis and planning the treatment of breast cancer. The false-positive rate is very low, with only a single case reported in 835 aspirates. Most false negatives are due to sampling and not to interpretive difficulties. The category "suspicious but not diagnostic of malignancy" serves a useful purpose in management of patients with breast lumps.

Uncertainty in biological monitoring: a framework for data collection and analysis to account for multiple sources of sampling bias

USGS Publications Warehouse

Ruiz-Gutierrez, Viviana; Hooten, Melvin B.; Campbell Grant, Evan H.

2016-01-01

Biological monitoring programmes are increasingly relying upon large volumes of citizen-science data to improve the scope and spatial coverage of information, challenging the scientific community to develop design and model-based approaches to improve inference.Recent statistical models in ecology have been developed to accommodate false-negative errors, although current work points to false-positive errors as equally important sources of bias. This is of particular concern for the success of any monitoring programme given that rates as small as 3% could lead to the overestimation of the occurrence of rare events by as much as 50%, and even small false-positive rates can severely bias estimates of occurrence dynamics.We present an integrated, computationally efficient Bayesian hierarchical model to correct for false-positive and false-negative errors in detection/non-detection data. Our model combines independent, auxiliary data sources with field observations to improve the estimation of false-positive rates, when a subset of field observations cannot be validated a posteriori or assumed as perfect. We evaluated the performance of the model across a range of occurrence rates, false-positive and false-negative errors, and quantity of auxiliary data.The model performed well under all simulated scenarios, and we were able to identify critical auxiliary data characteristics which resulted in improved inference. We applied our false-positive model to a large-scale, citizen-science monitoring programme for anurans in the north-eastern United States, using auxiliary data from an experiment designed to estimate false-positive error rates. Not correcting for false-positive rates resulted in biased estimates of occupancy in 4 of the 10 anuran species we analysed, leading to an overestimation of the average number of occupied survey routes by as much as 70%.The framework we present for data collection and analysis is able to efficiently provide reliable inference for occurrence patterns using data from a citizen-science monitoring programme. However, our approach is applicable to data generated by any type of research and monitoring programme, independent of skill level or scale, when effort is placed on obtaining auxiliary information on false-positive rates.

[Predictive factors of contamination in a blood culture with bacterial growth in an Emergency Department].

PubMed

Hernández-Bou, S; Trenchs Sainz de la Maza, V; Esquivel Ojeda, J N; Gené Giralt, A; Luaces Cubells, C

2015-06-01

The aim of this study is to identify predictive factors of bacterial contamination in positive blood cultures (BC) collected in an emergency department. A prospective, observational and analytical study was conducted on febrile children aged on to 36 months, who had no risk factors of bacterial infection, and had a BC collected in the Emergency Department between November 2011 and October 2013 in which bacterial growth was detected. The potential BC contamination predicting factors analysed were: maximum temperature, time to positivity, initial Gram stain result, white blood cell count, absolute neutrophil count, band count, and C-reactive protein (CRP). Bacteria grew in 169 BC. Thirty (17.8%) were finally considered true positives and 139 (82.2%) false positives. All potential BC contamination predicting factors analysed, except maximum temperature, showed significant differences between true positives and false positives. CRP value, time to positivity, and initial Gram stain result are the best predictors of false positives in BC. The positive predictive values of a CRP value≤30mg/L, BC time to positivity≥16h, and initial Gram stain suggestive of a contaminant in predicting a FP, are 95.1, 96.9 and 97.5%, respectively. When all 3 conditions are applied, their positive predictive value is 100%. Four (8.3%) patients with a false positive BC and discharged to home were revaluated in the Emergency Department. The majority of BC obtained in the Emergency Department that showed positive were finally considered false positives. Initial Gram stain, time to positivity, and CRP results are valuable diagnostic tests in distinguishing between true positives and false positives in BC. The early detection of false positives will allow minimising their negative consequences. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

Interpreting the results of the Semmes-Weinstein monofilament test: accounting for false-positive answers in the international consensus on the diabetic foot protocol by a new model.

PubMed

Slater, Robert A; Koren, Shlomit; Ramot, Yoram; Buchs, Andreas; Rapoport, Micha J

2014-01-01

The Semmes-Weinstein monofilament is the most widely used test to diagnose the loss of protective sensation. The commonly used protocol of the International Consensus on the Diabetic Foot includes a 'sham' application that allows for false-positive answers. We sought to study the heretofore unexamined significance of false-positive answers. Forty-five patients with diabetes and a history of pedal ulceration (Group I) and 81 patients with diabetes but no history of ulceration (Group II) were studied. The three original sites of the International Consensus on the Diabetic Foot at the hallux, 1st metatarsal and 5th metatarsal areas were used. At each location, the test was performed three times: 2 actual and 1 "sham" applications. Scores were graded from 0 to 3 based upon correct responses. Determination of loss of protective sensation was performed with and without calculating a false-positive answer as a minus 1 score. False-positive responses were found in a significant percentage of patients with and without history of ulceration. Introducing false-positive results as minus 1 into the test outcome significantly increased the number of patients diagnosed with loss of protective sensation in both groups. False-positive answers can significantly affect Semmes-Weinstein monofilament test results and the diagnosis of LOPS. A model that accounts for false-positive answers is offered. Copyright © 2013 John Wiley & Sons, Ltd.

Reducing false-positive incidental findings with ensemble genotyping and logistic regression based variant filtering methods.

PubMed

Hwang, Kyu-Baek; Lee, In-Hee; Park, Jin-Ho; Hambuch, Tina; Choe, Yongjoon; Kim, MinHyeok; Lee, Kyungjoon; Song, Taemin; Neu, Matthew B; Gupta, Neha; Kohane, Isaac S; Green, Robert C; Kong, Sek Won

2014-08-01

As whole genome sequencing (WGS) uncovers variants associated with rare and common diseases, an immediate challenge is to minimize false-positive findings due to sequencing and variant calling errors. False positives can be reduced by combining results from orthogonal sequencing methods, but costly. Here, we present variant filtering approaches using logistic regression (LR) and ensemble genotyping to minimize false positives without sacrificing sensitivity. We evaluated the methods using paired WGS datasets of an extended family prepared using two sequencing platforms and a validated set of variants in NA12878. Using LR or ensemble genotyping based filtering, false-negative rates were significantly reduced by 1.1- to 17.8-fold at the same levels of false discovery rates (5.4% for heterozygous and 4.5% for homozygous single nucleotide variants (SNVs); 30.0% for heterozygous and 18.7% for homozygous insertions; 25.2% for heterozygous and 16.6% for homozygous deletions) compared to the filtering based on genotype quality scores. Moreover, ensemble genotyping excluded > 98% (105,080 of 107,167) of false positives while retaining > 95% (897 of 937) of true positives in de novo mutation (DNM) discovery in NA12878, and performed better than a consensus method using two sequencing platforms. Our proposed methods were effective in prioritizing phenotype-associated variants, and an ensemble genotyping would be essential to minimize false-positive DNM candidates. © 2014 WILEY PERIODICALS, INC.

Reducing false positive incidental findings with ensemble genotyping and logistic regression-based variant filtering methods

PubMed Central

Hwang, Kyu-Baek; Lee, In-Hee; Park, Jin-Ho; Hambuch, Tina; Choi, Yongjoon; Kim, MinHyeok; Lee, Kyungjoon; Song, Taemin; Neu, Matthew B.; Gupta, Neha; Kohane, Isaac S.; Green, Robert C.; Kong, Sek Won

2014-01-01

As whole genome sequencing (WGS) uncovers variants associated with rare and common diseases, an immediate challenge is to minimize false positive findings due to sequencing and variant calling errors. False positives can be reduced by combining results from orthogonal sequencing methods, but costly. Here we present variant filtering approaches using logistic regression (LR) and ensemble genotyping to minimize false positives without sacrificing sensitivity. We evaluated the methods using paired WGS datasets of an extended family prepared using two sequencing platforms and a validated set of variants in NA12878. Using LR or ensemble genotyping based filtering, false negative rates were significantly reduced by 1.1- to 17.8-fold at the same levels of false discovery rates (5.4% for heterozygous and 4.5% for homozygous SNVs; 30.0% for heterozygous and 18.7% for homozygous insertions; 25.2% for heterozygous and 16.6% for homozygous deletions) compared to the filtering based on genotype quality scores. Moreover, ensemble genotyping excluded > 98% (105,080 of 107,167) of false positives while retaining > 95% (897 of 937) of true positives in de novo mutation (DNM) discovery, and performed better than a consensus method using two sequencing platforms. Our proposed methods were effective in prioritizing phenotype-associated variants, and ensemble genotyping would be essential to minimize false positive DNM candidates. PMID:24829188

Species classifier choice is a key consideration when analysing low-complexity food microbiome data.

PubMed

Walsh, Aaron M; Crispie, Fiona; O'Sullivan, Orla; Finnegan, Laura; Claesson, Marcus J; Cotter, Paul D

2018-03-20

The use of shotgun metagenomics to analyse low-complexity microbial communities in foods has the potential to be of considerable fundamental and applied value. However, there is currently no consensus with respect to choice of species classification tool, platform, or sequencing depth. Here, we benchmarked the performances of three high-throughput short-read sequencing platforms, the Illumina MiSeq, NextSeq 500, and Ion Proton, for shotgun metagenomics of food microbiota. Briefly, we sequenced six kefir DNA samples and a mock community DNA sample, the latter constructed by evenly mixing genomic DNA from 13 food-related bacterial species. A variety of bioinformatic tools were used to analyse the data generated, and the effects of sequencing depth on these analyses were tested by randomly subsampling reads. Compositional analysis results were consistent between the platforms at divergent sequencing depths. However, we observed pronounced differences in the predictions from species classification tools. Indeed, PERMANOVA indicated that there was no significant differences between the compositional results generated by the different sequencers (p = 0.693, R 2  = 0.011), but there was a significant difference between the results predicted by the species classifiers (p = 0.01, R 2  = 0.127). The relative abundances predicted by the classifiers, apart from MetaPhlAn2, were apparently biased by reference genome sizes. Additionally, we observed varying false-positive rates among the classifiers. MetaPhlAn2 had the lowest false-positive rate, whereas SLIMM had the greatest false-positive rate. Strain-level analysis results were also similar across platforms. Each platform correctly identified the strains present in the mock community, but accuracy was improved slightly with greater sequencing depth. Notably, PanPhlAn detected the dominant strains in each kefir sample above 500,000 reads per sample. Again, the outputs from functional profiling analysis using SUPER-FOCUS were generally accordant between the platforms at different sequencing depths. Finally, and expectedly, metagenome assembly completeness was significantly lower on the MiSeq than either on the NextSeq (p = 0.03) or the Proton (p = 0.011), and it improved with increased sequencing depth. Our results demonstrate a remarkable similarity in the results generated by the three sequencing platforms at different sequencing depths, and, in fact, the choice of bioinformatics methodology had a more evident impact on results than the choice of sequencer did.

Collective irrationality and positive feedback.

PubMed

Nicolis, Stamatios C; Zabzina, Natalia; Latty, Tanya; Sumpter, David J T

2011-04-26

Recent experiments on ants and slime moulds have assessed the degree to which they make rational decisions when presented with a number of alternative food sources or shelter. Ants and slime moulds are just two examples of a wide range of species and biological processes that use positive feedback mechanisms to reach decisions. Here we use a generic, experimentally validated model of positive feedback between group members to show that the probability of taking the best of options depends crucially on the strength of feedback. We show how the probability of choosing the best option can be maximized by applying an optimal feedback strength. Importantly, this optimal value depends on the number of options, so that when we change the number of options the preference of the group changes, producing apparent "irrationalities". We thus reinterpret the idea that collectives show "rational" or "irrational" preferences as being a necessary consequence of the use of positive feedback. We argue that positive feedback is a heuristic which often produces fast and accurate group decision-making, but is always susceptible to apparent irrationality when studied under particular experimental conditions.

12 CFR 1806.303 - Fraud, waste and abuse.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Fraud, waste and abuse. 1806.303 Section 1806... BANK ENTERPRISE AWARD PROGRAM Terms and Conditions of Assistance § 1806.303 Fraud, waste and abuse. Any person who becomes aware of the existence or apparent existence of fraud, waste, or abuse of assistance...

The problem of false positives and false negatives in violent video game experiments.

PubMed

Ferguson, Christopher J

The problem of false positives and negatives has received considerable attention in behavioral research in recent years. The current paper uses video game violence research as an example of how such issues may develop in a field. Despite decades of research, evidence on whether violent video games (VVGs) contribute to aggression in players has remained mixed. Concerns have been raised in recent years that experiments regarding VVGs may suffer from both "false positives" and "false negatives." The current paper examines this issue in three sets of video game experiments, two sets of video game experiments on aggression and prosocial behaviors identified in meta-analysis, and a third group of recent null studies. Results indicated that studies of VVGs and aggression appear to be particularly prone to false positive results. Studies of VVGs and prosocial behavior, by contrast are heterogeneous and did not demonstrate any indication of false positive results. However, their heterogeneous nature made it difficult to base solid conclusions on them. By contrast, evidence for false negatives in null studies was limited, and little evidence emerged that null studies lacked power in comparison those highlighted in past meta-analyses as evidence for effects. These results are considered in light of issues related to false positives and negatives in behavioral science more broadly. Copyright © 2017 Elsevier Ltd. All rights reserved.

Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

PubMed Central

Shanks, Leslie; Ritmeijer, Koert; Piriou, Erwan; Siddiqui, M. Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Masiga, Johnson; Abebe, Almaz

2015-01-01

Background Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals. Methodology/Principal Findings Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively). Conclusion The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study. PMID:26161864

Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

PubMed

Shanks, Leslie; Ritmeijer, Koert; Piriou, Erwan; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Masiga, Johnson; Abebe, Almaz

2015-01-01

Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals. Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively). The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study.

Relevance of cutoff on a 4th generation ELISA performance in the false positive rate during HIV diagnostic in a low HIV prevalence setting.

PubMed

Chacón, Lucía; Mateos, María Luisa; Holguín, África

2017-07-01

Despite the high specificity of fourth-generation enzyme immunoassays (4th-gen-EIA) for screening during HIV diagnosis, their positive predictive value is low in populations with low HIV prevalence. Thus, screening should be optimized to reduce false positive results. The influence of sample cutoff (S/CO) values by a 4th-gen-EIA with the false positive rate during the routine HIV diagnosis in a low HIV prevalence population was evaluated. A total of 30,201 sera were tested for HIV diagnosis using Abbott Architect ® HIV-Ag/Ab-Combo 4th-gen-EIA at a hospital in Spain during 17 months. Architect S/CO values were recorded, comparing the HIV-1 positive results following Architect interpretation (S/CO≥1) with the final HIV-1 diagnosis by confirmatory tests (line immunoassay, LIA and/or nucleic acid test, NAT). ROC curve was also performed. Among the 30,201 HIV performed tests, 256 (0.85%) were positive according to Architect interpretation (S/CO≥1) but only 229 (0.76%) were definitively HIV-1 positive after LIA and/or NAT. Thus, 27 (10.5%) of 256 samples with S/CO≥1 by Architect were false positive diagnose. The false positive rate decreased when the S/CO ratio increased. All 19 samples with S/CO ≤10 were false positives and all 220 with S/CO>50 true HIV-positives. The optimal S/CO cutoff value provided by ROC curves was 32.7. No false negative results were found. We show that very low S/CO values during HIV-1 screening using Architect can result HIV negative after confirmation by LIA and NAT. The false positive rate is reduced when S/CO increases. Copyright © 2017 Elsevier B.V. All rights reserved.

Which Factors Contribute to False-Positive, False-Negative, and Invalid Results in Fetal Fibronectin Testing in Women with Symptoms of Preterm Labor?

PubMed

Bruijn, Merel M C; Hermans, Frederik J R; Vis, Jolande Y; Wilms, Femke F; Oudijk, Martijn A; Kwee, Anneke; Porath, Martina M; Oei, Guid; Scheepers, Hubertina C J; Spaanderman, Marc E A; Bloemenkamp, Kitty W M; Haak, Monique C; Bolte, Antoinette C; Vandenbussche, Frank P H A; Woiski, Mallory D; Bax, Caroline J; Cornette, Jérôme M J; Duvekot, Johannes J; Bijvank, Bas W A N I J; van Eyck, Jim; Franssen, Maureen T M; Sollie, Krystyna M; van der Post, Joris A M; Bossuyt, Patrick M M; Kok, Marjolein; Mol, Ben W J; van Baaren, Gert-Jan

2017-02-01

Objective  We assessed the influence of external factors on false-positive, false-negative, and invalid fibronectin results in the prediction of spontaneous delivery within 7 days. Methods  We studied symptomatic women between 24 and 34 weeks' gestational age. We performed uni- and multivariable logistic regression to estimate the effect of external factors (vaginal soap, digital examination, transvaginal sonography, sexual intercourse, vaginal bleeding) on the risk of false-positive, false-negative, and invalid results, using spontaneous delivery within 7 days as the outcome. Results  Out of 708 women, 237 (33%) had a false-positive result; none of the factors showed a significant association. Vaginal bleeding increased the proportion of positive fetal fibronectin (fFN) results, but was significantly associated with a lower risk of false-positive test results (odds ratio [OR], 0.22; 95% confidence intervals [CI], 0.12-0.39). Ten women (1%) had a false-negative result. None of the investigated factors was significantly associated with a significantly higher risk of false-negative results. Twenty-one tests (3%) were invalid; only vaginal bleeding showed a significant association (OR, 4.5; 95% CI, 1.7-12). Conclusion  The effect of external factors on the performance of qualitative fFN testing is limited, with vaginal bleeding as the only factor that reduces its validity. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Consensus-based identification of factors related to false-positives in ultrasound scanning of synovitis and tenosynovitis.

PubMed

Ikeda, Kei; Narita, Akihiro; Ogasawara, Michihiro; Ohno, Shigeru; Kawahito, Yutaka; Kawakami, Atsushi; Ito, Hiromu; Matsushita, Isao; Suzuki, Takeshi; Misaki, Kenta; Ogura, Takehisa; Kamishima, Tamotsu; Seto, Yohei; Nakahara, Ryuichi; Kaneko, Atsushi; Nakamura, Takayuki; Henmi, Mihoko; Fukae, Jun; Nishida, Keiichiro; Sumida, Takayuki; Koike, Takao

2016-01-01

We aimed to identify causes of false-positives in ultrasound scanning of synovial/tenosynovial/bursal inflammation and provide corresponding imaging examples. We first performed systematic literature review to identify previously reported causes of false-positives. We next determined causes of false-positives and corresponding example images for educational material through Delphi exercises and discussion by 15 experts who were an instructor and/or a lecturer in the 2013 advanced course for musculoskeletal ultrasound organized by Japan College of Rheumatology Committee for the Standardization of Musculoskeletal Ultrasonography. Systematic literature review identified 11 articles relevant to sonographic false-positives of synovial/tenosynovial inflammation. Based on these studies, 21 candidate causes of false-positives were identified in the consensus meeting. Of these items, 11 achieved a predefined consensus (≥ 80%) in Delphi exercise and were classified as follows: (I) Gray-scale assessment [(A) non-specific synovial findings and (B) normal anatomical structures which can mimic synovial lesions due to either their low echogenicity or anisotropy]; (II) Doppler assessment [(A) Intra-articular normal vessels and (B) reverberation)]. Twenty-four corresponding examples with 49 still and 23 video images also achieved consensus. Our study provides a set of representative images that can help sonographers to understand false-positives in ultrasound scanning of synovitis and tenosynovitis.

Skin irritation, false positives and the local lymph node assay: a guideline issue?

PubMed

Basketter, David A; Kimber, Ian

2011-10-01

Since the formal validation and regulatory acceptance of the local lymph node assay (LLNA) there have been commentaries suggesting that the irritant properties of substances can give rise to false positives. As toxicology aspires to progress rapidly towards the age of in vitro alternatives, it is of increasing importance that issues relating to assay selectivity and performance are understood fully, and that true false positive responses are distinguished clearly from those that are simply unpalatable. In the present review, we have focused on whether skin irritation per se is actually a direct cause of true false positive results in the LLNA. The body of published work has been examined critically and considered in relation to our current understanding of the mechanisms of skin irritation and skin sensitisation. From these analyses it is very clear that, of itself, skin irritation is not a cause of false positive results. The corollary is, therefore, that limiting test concentrations in the LLNA for the purpose of avoiding skin irritation may lead, unintentionally, to false negatives. Where a substance is a true false positive in the LLNA, the classic example being sodium lauryl sulphate, explanations for that positivity will have to reach beyond the seductive, but incorrect, recourse to its skin irritation potential. Copyright © 2011 Elsevier Inc. All rights reserved.

Hypertension is strongly associated with false-positive bicycle exercise stress echocardiography testing results.

PubMed

Keller, Karsten; Stelzer, Kathrin; Munzel, Thomas; Ostad, Mir Abolfazl

2016-12-01

Exercise echocardiography is a reliable routine test in patients with known or suspected coronary artery disease. However, in ∼15% of all patients, stress echocardiography leads to false-positive stress echocardiography results. We aimed to investigate the impact of hypertension on stress echocardiographic results. We performed a retrospective study of patients with suspected or known stable coronary artery disease who underwent a bicycle exercise stress echocardiography. Patients with false-positive stress results were compared with those with appropriate results. 126 patients with suspected or known coronary artery disease were included in this retrospective study. 23 patients showed false-positive stress echocardiography results. Beside comparable age, gender distribution and coronary artery status, hypertension was more prevalent in patients with false-positive stress results (95.7% vs. 67.0%, p = 0.0410). Exercise peak load revealed a borderline-significance with lower loads in patients with false-positive results (100.0 (IQR 75.0/137.5) vs. 125.0 (100.0/150.0) W, p = 0.0601). Patients with false-positive stress results showed higher systolic (2.05 ± 0.69 vs. 1.67 ± 0.39 mmHg/W, p = 0.0193) and diastolic (1.03 ± 0.38 vs. 0.80 ± 0.28 mmHg/W, p = 0.0165) peak blood pressure (BP) per wattage. In a multivariate logistic regression test, hypertension (OR 17.6 [CI 95% 1.9-162.2], p = 0.0115), and systolic (OR 4.12 [1.56-10.89], p = 0.00430) and diastolic (OR 13.74 [2.46-76.83], p = 0.00285) peak BP per wattage, were associated with false-positive exercise results. ROC analysis for systolic and diastolic peak BP levels per wattage showed optimal cut-off values of 1.935mmHg/W and 0.823mmHg/W, indicating false-positive exercise echocardiographic results with AUCs of 0.660 and 0.664, respectively. Hypertension is a risk factor for false-positive stress exercise echocardiographic results in patients with known or suspected coronary artery disease. Presence of hypertension was associated with 17.6-fold elevated risk of false-positive results.

Characterization of Actinides Complexed to Nuclear Fuel Constituents Using ESI-MS.

PubMed

McDonald, Luther W; Campbell, James A; Vercouter, Thomas; Clark, Sue B

2016-03-01

Electrospray ionization-mass spectrometry (ESI-MS) was tested for its use in monitoring spent nuclear fuel (SNF) constituents including U, Pu, dibutyl phosphate (DBP), and tributyl phosphate (TBP). Both positive and negative ion modes were used to evaluate the speciation of U and Pu with TBP and DBP. Furthermore, apparent stability constants were determined for U complexed to TBP and DBP. In positive ion mode, TBP produced a strong signal with and without complexation to U or Pu, but, in negative ion mode, no TBP, U-TBP, or Pu-TBP complexes were observed. Apparent stability constants were determined for [UO2(NO3)2(TBP)2], [UO2(NO3)2(H2O)(TBP)2], and [UO2(NO3)2(TBP)3]. In contrast DBP, U-DBP, and Pu-DBP complexes were observed in both positive and negative ion modes. Apparent stability constants were determined for the species [UO2(DBP)], [UO2(DBP)3], and [UO2(DBP)4]. Analyzing mixtures of U or Pu with TBP and DBP yielded the formation of ternary complexes whose stoichiometry was directly related to the ratio of TBP to DBP. The ESI-MS protocols used in this study will further demonstrate the utility of ESI-MS and its applicability to process control monitoring in SNF reprocessing facilities.

Comparative diagnostic efficacy of recombinant LLO and PI-PLC-based ELISAs for detection of listeriosis in animals.

PubMed

Suryawanshi, Rahul D; Malik, Satya Veer Singh; Jayarao, Bhushan; Chaudhari, Sandeep P; Savage, Emily; Vergis, Jess; Kurkure, Nitin V; Barbuddhe, Sukhadeo B; Rawool, Deepak B

2017-06-01

The present study for the first time evaluates the serodiagnostic efficacy of two recombinant antigens namely, listeriolysin O (rLLO) and phosphatidyl-inositol phospholipase C (rPI-PLC). Indirect ELISA with the above recombinant antigens was used on samples collected from bovines (n=106), goats (n=138) and pigs (n=92) having either a history of abortion, emaciation and/or apparently healthy animals. Isolation of Listeria was attempted from the blood samples using USDA-FSIS method. On screening of test sera by rLLO-based ELISA, antibodies against anti-listeriolysin O (ALLO) were observed in goats (22.46%), bovines (15.10%) and pigs (16.31%). As advocated, after adsorption of positive serum samples with streptolysin O (SLO), the seropositivity for ALLO was marginally reduced (p>0.05) in goats (21.73%) and bovines (10.38%), whereas, in pigs the reduction (5.43%) was significant (p<0.05). On the contrary, rPI-PLC-based ELISA revealed higher non-specific seropositivity for antilisterial antibodies in goats (45.65%), bovines (31.13%) and pigs (8.69%). Further, on comparing the seropositivity with isolation rate, of the 16 animals that were culturally-positive for L. monocytogenes, 15 showed ALLO positivity in unadsorbed as well as SLO-adsorbed sera by rLLO-based ELISA, however, rPI-PLC-based ELISA could detect seropositivity in only 5 animals. Moreover, rPI-PLC-based ELISA also showed seropositivity in those animals (7/30) that were culturally positive for other Listeria spp. In conclusion, rLLO can serve as a better antigen than rPI-PLC in ELISA for the serodiagnosis of listeriosis in animals; however, prior adsorption of test sera with SLO is required to avoid false positive results. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection of Japanese Encephalitis Virus RNA in Human Throat Samples in Laos - A Pilot study.

PubMed

Bharucha, Tehmina; Sengvilaipaseuth, Onanong; Seephonelee, Malee; Vongsouvath, Malavanh; Vongsouvath, Manivanh; Rattanavong, Sayaphet; Piorkowski, Géraldine; Lecuit, Marc; Gorman, Christopher; Pommier, Jean-David; Newton, Paul N; de Lamballerie, Xavier; Dubot-Pérès, Audrey

2018-05-22

Japanese encephalitis virus (JEV) is the most commonly identified cause of acute encephalitis syndrome (AES) in Asia. The WHO recommended test is anti-JEV IgM-antibody-capture-enzyme-linked-immunosorbent-assay (JEV MAC-ELISA). However, data suggest this has low positive predictive value, with false positives related to other Flavivirus infections and vaccination. JEV RT-PCR in cerebrospinal fluid (CSF) and/or serum is highly specific, but is rarely positive; 0-25% of patients that fulfil the WHO definition of JE (clinical Acute Encephalitis Syndrome (AES) and JEV MAC-ELISA positive). Testing other body fluids by JEV RT-qPCR may improve the diagnosis. As a pilot study thirty patients admitted to Mahosot Hospital 2014-2017, recruited to the South-East-Asia-Encephalitis study, were tested by JEV MAC-ELISA and two JEV real-time RT-PCR (RT-qPCR) assays (NS2A and NS3). Eleven (36.7%) were JEV MAC-ELISA positive. Available CSF and serum samples of these patients were JEV RT-qPCR negative but 2 (7%) had JEV RNA detected in their throat swabs. JEV RNA was confirmed by re-testing, and sequencing of RT-qPCR products. As the first apparent report of JEV RNA detection in human throat samples, the provides new perspectives on human JEV infection, potentially informing improving JEV detection. We suggest that testing patients' throat swabs for JEV RNA is performed, in combination with molecular and serological CSF and serum investigations, on a larger scale to investigate the epidemiology of the presence of JEV in human throats. Throat swabs are an easy and non-invasive tool that could be rolled out to a wider population to improve knowledge of JEV molecular epidemiology.

False Recognition in Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease-Disinhibition or Amnesia?

PubMed

Flanagan, Emma C; Wong, Stephanie; Dutt, Aparna; Tu, Sicong; Bertoux, Maxime; Irish, Muireann; Piguet, Olivier; Rao, Sulakshana; Hodges, John R; Ghosh, Amitabha; Hornberger, Michael

2016-01-01

Episodic memory recall processes in Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) can be similarly impaired, whereas recognition performance is more variable. A potential reason for this variability could be false-positive errors made on recognition trials and whether these errors are due to amnesia per se or a general over-endorsement of recognition items regardless of memory. The current study addressed this issue by analysing recognition performance on the Rey Auditory Verbal Learning Test (RAVLT) in 39 bvFTD, 77 AD and 61 control participants from two centers (India, Australia), as well as disinhibition assessed using the Hayling test. Whereas both AD and bvFTD patients were comparably impaired on delayed recall, bvFTD patients showed intact recognition performance in terms of the number of correct hits. However, both patient groups endorsed significantly more false-positives than controls, and bvFTD and AD patients scored equally poorly on a sensitivity index (correct hits-false-positives). Furthermore, measures of disinhibition were significantly associated with false positives in both groups, with a stronger relationship with false-positives in bvFTD. Voxel-based morphometry analyses revealed similar neural correlates of false positive endorsement across bvFTD and AD, with both patient groups showing involvement of prefrontal and Papez circuitry regions, such as medial temporal and thalamic regions, and a DTI analysis detected an emerging but non-significant trend between false positives and decreased fornix integrity in bvFTD only. These findings suggest that false-positive errors on recognition tests relate to similar mechanisms in bvFTD and AD, reflecting deficits in episodic memory processes and disinhibition. These findings highlight that current memory tests are not sufficient to accurately distinguish between bvFTD and AD patients.

Non-invasive detection of infection in acute pancreatic and acute necrotic collections with diffusion-weighted magnetic resonance imaging: preliminary findings.

PubMed

Islim, Filiz; Salik, Aysun Erbahceci; Bayramoglu, Sibel; Guven, Koray; Alis, Halil; Turhan, Ahmet Nuray

2014-06-01

The purpose of this study was to evaluate the contribution of diffusion-weighted magnetic resonance imaging (DW-MRI) to the detection of infection in acute pancreatitis-related collections. A total of 21 DW-MRI, and computed tomography (CT) were performed on 20 patients diagnosed as acute pancreatitis with acute peri-pancreatic fluid or necrotic collections. Collections were classified as infected or sterile according to the culture and follow-up results. Collections with gas bubbles on CT images were considered to be infected. Collections with peripheral bright signals on DW-MRI images were considered to be positive, whereas those without signals were considered to be negative. Apparent diffusion coefficient (ADC) values of the peripheral and central parts of the collections were measured. Student's t test was used to compare the means of ADC values of independent groups. Apart from one false positive result, the presence of infection was detected by DW-MRI with 95.2% accuracy. The sensitivity and accuracy of DW-MRI were higher than CT for the detection of infection. The ADC values in the central parts of the collections were significantly different between the infected and sterile groups. DW-MRI can be used as a non-invasive technique for the detection of infection in acute pancreatitis-associated collections.

False-positive buprenorphine EIA urine toxicology results due to high dose morphine: a case report.

PubMed

Tenore, Peter L

2012-01-01

In monitoring a patient with chronic pain who was taking high-dose morphine and oxycodone with weekly urine enzymatic immunoassay (EIA) toxicology testing, the authors noted consistent positives for buprenorphine. The patient was not taking buprenorphine, and gas chromatography/mass spectroscopy (GCMS) testing on multiple samples revealed no buprenorphine, indicating a case of false-positive buprenorphine EIAs in a high-dose opiate case. The authors discontinued oxycodone for a period of time and then discontinued morphine. Urine monitoring with EIAs and GCMS revealed false-positive buprenorphine EIAs, which remained only when the patient was taking morphine. When taking only oxycodone and no morphine, urine samples became buprenorphine negative. When morphine was reintroduced, false-positive buprenorphine results resumed. Medical practitioners should be aware that high-dose morphine (with morphine urine levels turning positive within the 15,000 to 28,000 mg/mL range) may produce false-positive buprenorphine EIAs with standard urine EIA toxicology testing.

Diurnal rhythm and concordance between objective and subjective hot flashes: the Hilo Women's Health Study.

PubMed

Sievert, Lynnette L; Reza, Angela; Mills, Phoebe; Morrison, Lynn; Rahberg, Nichole; Goodloe, Amber; Sutherland, Michael; Brown, Daniel E

2010-01-01

The aims of this study were to test for a diurnal pattern in hot flashes in a multiethnic population living in a hot, humid environment and to examine the rates of concordance between objective and subjective measures of hot flashes using ambulatory and laboratory measures. Study participants aged 45 to 55 years were recruited from the general population of Hilo, HI. Women wore a Biolog hot flash monitor (UFI, Morro Bay, CA), kept a diary for 24 hours, and also participated in 3-hour laboratory measures (n = 199). Diurnal patterns were assessed using polynomial regression. For each woman, objectively recorded hot flashes that matched subjective experience were treated as true-positive readings. Subjective hot flashes were considered the standard for computing false-positive and false-negative readings. True-positive, false-positive, and false-negative readings were compared across ethnic groups by chi analyses. Frequencies of sternal, nuchal, and subjective hot flashes peaked at 1500 +/- 1 hours with no difference by ethnicity. Laboratory results supported the pattern seen in ambulatory monitoring. Sternal and nuchal monitoring showed the same frequency of true-positive measures, but nonsternal electrodes picked up more false-positive readings. Laboratory monitoring showed very low frequencies of false negatives. There were no ethnic differences in the frequency of true-positive or false-positive measures. Women of European descent were more likely to report hot flashes that were not objectively demonstrated (false-negative measures). The diurnal pattern and peak in hot flash occurrence in the hot humid environment of Hilo were similar to results from more temperate environments. Lack of variation in sternal versus nonsternal measures and in true-positive measures across ethnicities suggests no appreciable effect of population variation in sweating patterns.

Diurnal rhythm and concordance between objective and subjective hot flashes: The Hilo Women’s Health Study

PubMed Central

Sievert, Lynnette L.; Reza, Angela; Mills, Phoebe; Morrison, Lynn; Rahberg, Nichole; Goodloe, Amber; Sutherland, Michael; Brown, Daniel E.

2010-01-01

Objective To test for a diurnal pattern in hot flashes in a multi-ethnic population living in a hot, humid environment. To examine rates of concordance between objective and subjective measures of hot flashes using ambulatory and laboratory measures. Methods Study participants aged 45–55 were recruited from the general population of Hilo, Hawaii. Women wore a Biolog hot flash monitor, kept a diary for 24-hours, and also participated in 3-hour laboratory measures (n=199). Diurnal patterns were assessed using polynomial regression. For each woman, objectively recorded hot flashes that matched subjective experience were treated as true positive readings. Subjective hot flashes were considered the standard for computing false positive and false negative readings. True positive, false positive, and false negative readings were compared across ethnic groups by chi-square analyses. Results Frequencies of sternal, nuchal and subjective hot flashes peaked at 15:00 ± 1 hour with no difference by ethnicity. Laboratory results supported the pattern seen in ambulatory monitoring. Sternal and nuchal monitoring showed the same frequency of true positive measures, but non-sternal electrodes picked up more false positive readings. Laboratory monitoring showed very low frequencies of false negatives. There were no ethnic differences in the frequency of true positive or false positive measures. Women of European descent were more likely to report hot flashes that were not objectively demonstrated (false negative measures). Conclusions The diurnal pattern and peak in hot flash occurrence in the hot humid environment of Hilo was similar to results from more temperate environments. Lack of variation in sternal vs. non-sternal measures, and in true positive measures across ethnicities suggests no appreciable effect of population variation in sweating patterns. PMID:20220538

Ignoring Intermarker Linkage Disequilibrium Induces False-Positive Evidence of Linkage for Consanguineous Pedigrees when Genotype Data Is Missing for Any Pedigree Member

PubMed Central

Li, Bingshan; Leal, Suzanne M.

2008-01-01

Missing genotype data can increase false-positive evidence for linkage when either parametric or nonparametric analysis is carried out ignoring intermarker linkage disequilibrium (LD). Previously it was demonstrated by Huang et al. [1] that no bias occurs in this situation for affected sib-pairs with unrelated parents when either both parents are genotyped or genotype data is available for two additional unaffected siblings when parental genotypes are missing. However, this is not the case for autosomal recessive consanguineous pedigrees, where missing genotype data for any pedigree member within a consanguinity loop can increase false-positive evidence of linkage. False-positive evidence for linkage is further increased when cryptic consanguinity is present. The amount of false-positive evidence for linkage, and which family members aid in its reduction, is highly dependent on which family members are genotyped. When parental genotype data is available, the false-positive evidence for linkage is usually not as strong as when parental genotype data is unavailable. For a pedigree with an affected proband whose first-cousin parents have been genotyped, further reduction in the false-positive evidence of linkage can be obtained by including genotype data from additional affected siblings of the proband or genotype data from the proband's sibling-grandparents. For the situation, when parental genotypes are unavailable, false-positive evidence for linkage can be reduced by including genotype data from either unaffected siblings of the proband or the proband's married-in-grandparents in the analysis. PMID:18073490

Biological false-positive venereal disease research laboratory test in cerebrospinal fluid in the diagnosis of neurosyphilis - a case-control study.

PubMed

Zheng, S; Lin, R J; Chan, Y H; Ngan, C C L

2018-03-01

There is no clear consensus on the diagnosis of neurosyphilis. The Venereal Disease Research Laboratory (VDRL) test from cerebrospinal fluid (CSF) has traditionally been considered the gold standard for diagnosing neurosyphilis but is widely known to be insensitive. In this study, we compared the clinical and laboratory characteristics of true-positive VDRL-CSF cases with biological false-positive VDRL-CSF cases. We retrospectively identified cases of true and false-positive VDRL-CSF across a 3-year period received by the Immunology and Serology Laboratory, Singapore General Hospital. A biological false-positive VDRL-CSF is defined as a reactive VDRL-CSF with a non-reactive Treponema pallidum particle agglutination (TPPA)-CSF and/or negative Line Immuno Assay (LIA)-CSF IgG. A true-positive VDRL-CSF is a reactive VDRL-CSF with a concordant reactive TPPA-CSF and/or positive LIA-CSF IgG. During the study period, a total of 1254 specimens underwent VDRL-CSF examination. Amongst these, 60 specimens from 53 patients tested positive for VDRL-CSF. Of the 53 patients, 42 (79.2%) were true-positive cases and 11 (20.8%) were false-positive cases. In our setting, a positive non-treponemal serology has 97.6% sensitivity, 100% specificity, 100% positive predictive value and 91.7% negative predictive value for a true-positive VDRL-CSF based on our laboratory definition. HIV seropositivity was an independent predictor of a true-positive VDRL-CSF. Biological false-positive VDRL-CSF is common in a setting where patients are tested without first establishing a serological diagnosis of syphilis. Serological testing should be performed prior to CSF evaluation for neurosyphilis. © 2017 European Academy of Dermatology and Venereology.

False positive circumsporozoite protein ELISA: a challenge for the estimation of the entomological inoculation rate of malaria and for vector incrimination

PubMed Central

2011-01-01

Background The entomological inoculation rate (EIR) is an important indicator in estimating malaria transmission and the impact of vector control. To assess the EIR, the enzyme-linked immunosorbent assay (ELISA) to detect the circumsporozoite protein (CSP) is increasingly used. However, several studies have reported false positive results in this ELISA. The false positive results could lead to an overestimation of the EIR. The aim of present study was to estimate the level of false positivity among different anopheline species in Cambodia and Vietnam and to check for the presence of other parasites that might interact with the anti-CSP monoclonal antibodies. Methods Mosquitoes collected in Cambodia and Vietnam were identified and tested for the presence of sporozoites in head and thorax by using CSP-ELISA. ELISA positive samples were confirmed by a Plasmodium specific PCR. False positive mosquitoes were checked by PCR for the presence of parasites belonging to the Haemosporidia, Trypanosomatidae, Piroplasmida, and Haemogregarines. The heat-stability and the presence of the cross-reacting antigen in the abdomen of the mosquitoes were also checked. Results Specimens (N = 16,160) of seven anopheline species were tested by CSP-ELISA for Plasmodium falciparum and Plasmodium vivax (Pv210 and Pv247). Two new vector species were identified for the region: Anopheles pampanai (P. vivax) and Anopheles barbirostris (Plasmodium malariae). In 88% (155/176) of the mosquitoes found positive with the P. falciparum CSP-ELISA, the presence of Plasmodium sporozoites could not be confirmed by PCR. This percentage was much lower (28% or 5/18) for P. vivax CSP-ELISAs. False positive CSP-ELISA results were associated with zoophilic mosquito species. None of the targeted parasites could be detected in these CSP-ELISA false positive mosquitoes. The ELISA reacting antigen of P. falciparum was heat-stable in CSP-ELISA true positive specimens, but not in the false positives. The heat-unstable cross-reacting antigen is mainly present in head and thorax and almost absent in the abdomens (4 out of 147) of the false positive specimens. Conclusion The CSP-ELISA can considerably overestimate the EIR, particularly for P. falciparum and for zoophilic species. The heat-unstable cross-reacting antigen in false positives remains unknown. Therefore it is highly recommended to confirm all positive CSP-ELISA results, either by re-analysing the heated ELISA lysate (100°C, 10 min), or by performing Plasmodium specific PCR followed if possible by sequencing of the amplicons for Plasmodium species determination. PMID:21767376

[Applying competitive polymerase chain reaction to the detection of hepatitis B virus DNA].

PubMed

Wang, Ling; Yang, Peng; Li, Shuang-qing; Xu, Shu-hui; Cao, Gui-qun; Zhang, Fa-qiang; Zhang, Mei-xia; Chen, Qing-ying; Xia, Qing-jie; Liu, Kai; Tang, Fang; Zhang, Yuan-zheng

2004-11-01

To reduce the rate of accidental false negative result in the HBV DNA PCR test on clinical serum samples. A competitive polymerase chain reaction (C-PCR) was used to decrease the false negative ratio. In the C-PCR, a constructed inner control DNA was added for co-amplification with the HBV target DNA. In a 20 microl C-PCR system, about 60 to 200 copies of inner control DNA could give apparent co-amplification signal band after electrophoresis on a 2% agarose gel. Five of 120 samples of clinical serum (4.2%) could not be amplified. C-PCR has the advantage of yielding information on false negative in the HBV DNA PCR assay of clinical serum samples.

77 FR 48045 - Supplemental Nutrition Assistance Program: Disqualified Recipient Reporting and Computer Matching...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

... false positive match rate of 10 percent. Making the match mandatory for the States who did not perform... number of prisoners from 1995 to 2013 and assumed a 10 percent false positive match rate. Finally, we... matches are false positives. We estimate that mandatory matches at certification will identify an...

Raising Achievement through Inclusion

ERIC Educational Resources Information Center

Persson, Elisabeth

2013-01-01

In 2007, Swedish authorities introduced open publication of comparisons of students' results at the end of compulsory school. In this study, we investigated a municipality that had succeeded in breaking a negative trend from a bottom position in the ranking in 2007 to a top position in 2010, apparently through inclusive practices. The purpose of…

Bladder cancer diagnosis with CT urography: test characteristics and reasons for false-positive and false-negative results.

PubMed

Trinh, Tony W; Glazer, Daniel I; Sadow, Cheryl A; Sahni, V Anik; Geller, Nina L; Silverman, Stuart G

2018-03-01

To determine test characteristics of CT urography for detecting bladder cancer in patients with hematuria and those undergoing surveillance, and to analyze reasons for false-positive and false-negative results. A HIPAA-compliant, IRB-approved retrospective review of reports from 1623 CT urograms between 10/2010 and 12/31/2013 was performed. 710 examinations for hematuria or bladder cancer history were compared to cystoscopy performed within 6 months. Reference standard was surgical pathology or 1-year minimum clinical follow-up. False-positive and false-negative examinations were reviewed to determine reasons for errors. Ninety-five bladder cancers were detected. CT urography accuracy: was 91.5% (650/710), sensitivity 86.3% (82/95), specificity 92.4% (568/615), positive predictive value 63.6% (82/129), and negative predictive value was 97.8% (568/581). Of 43 false positives, the majority of interpretation errors were due to benign prostatic hyperplasia (n = 12), trabeculated bladder (n = 9), and treatment changes (n = 8). Other causes include blood clots, mistaken normal anatomy, infectious/inflammatory changes, or had no cystoscopic correlate. Of 13 false negatives, 11 were due to technique, one to a large urinary residual, one to artifact. There were no errors in perception. CT urography is an accurate test for diagnosing bladder cancer; however, in protocols relying predominantly on excretory phase images, overall sensitivity remains insufficient to obviate cystoscopy. Awareness of bladder cancer mimics may reduce false-positive results. Improvements in CTU technique may reduce false-negative results.

Methods for threshold determination in multiplexed assays

DOEpatents

Tammero, Lance F. Bentley; Dzenitis, John M; Hindson, Benjamin J

2014-06-24

Methods for determination of threshold values of signatures comprised in an assay are described. Each signature enables detection of a target. The methods determine a probability density function of negative samples and a corresponding false positive rate curve. A false positive criterion is established and a threshold for that signature is determined as a point at which the false positive rate curve intersects the false positive criterion. A method for quantitative analysis and interpretation of assay results together with a method for determination of a desired limit of detection of a signature in an assay are also described.

Shear-wave elastography in the diagnosis of solid breast masses: what leads to false-negative or false-positive results?

PubMed

Yoon, Jung Hyun; Jung, Hae Kyoung; Lee, Jong Tae; Ko, Kyung Hee

2013-09-01

To investigate the factors that have an effect on false-positive or false-negative shear-wave elastography (SWE) results in solid breast masses. From June to December 2012, 222 breast lesions of 199 consecutive women (mean age: 45.3 ± 10.1 years; range, 21 to 88 years) who had been scheduled for biopsy or surgical excision were included. Greyscale ultrasound and SWE were performed in all women before biopsy. Final ultrasound assessments and SWE parameters (pattern classification and maximum elasticity) were recorded and compared with histopathology results. Patient and lesion factors in the 'true' and 'false' groups were compared. Of the 222 masses, 175 (78.8 %) were benign, and 47 (21.2 %) were malignant. False-positive rates of benign masses were significantly higher than false-negative rates of malignancy in SWE patterns, 36.6 % to 6.4 % (P < 0.001). Among both benign and malignant masses, factors showing significance among false SWE features were lesion size, breast thickness and lesion depth (all P < 0.05). All 47 malignant breast masses had SWE images of good quality. False SWE features were more significantly seen in benign masses. Lesion size, breast thickness and lesion depth have significance in producing false results, and this needs consideration in SWE image acquisition. • Shear-wave elastography (SWE) is widely used during breast imaging • At SWE, false-positive rates were significantly higher than false-negative rates • Larger size, breast thickness, depth and fair quality influences false-positive SWE features • Smaller size, larger breast thickness and depth influences false-negative SWE features.

O-acetylserine (thiol) lyase: an enigmatic enzyme of plant cysteine biosynthesis revisited in Arabidopsis thaliana.

PubMed

Wirtz, Markus; Droux, Michel; Hell, Rüdiger

2004-08-01

The synthesis of cysteine is positioned at a decisive stage of assimilatory sulphate reduction, marking the fixation of inorganic sulphide into a carbon skeleton. O-acetylserine (thiol) lyase (OAS-TL) catalyses the reaction of inorganic sulphide with O-acetylserine (OAS). Despite its prominent position in the pathway OAS-TL is generally regarded as a non-limiting enzyme without regulatory function, due to low substrate affinities and semi-constitutive expression patterns. To resolve this apparent contradiction, the kinetic properties of three OAS-TLs from Arabidopsis thaliana, localized in the cytosol (A), plastids (B), and mitochondria (C), were analysed. The recombinant expressed OAS-TLs were purified to apparent homogeneity without any fusion tag to maintain their native forms. The proteins displayed high specific activities of 550-900 micromol min(-1) mg(-1). Using an improved and highly sensitive assay method for cysteine determination, the apparent K(m)(sulphide) was 3-6 microM for OAS-TL A, B, and C and thus 10-100 times lower than previously reported for plant OAS-TLs. K(m)(OAS) was between 310 microM and 690 microM for OAS-TL isoform A, B, and C, whereas the apparent dissociation binding constant for OAS was much lower (K(d)<1 microM OAS). A HPLC method was developed for OAS quantification that revealed fast increases of the cellular OAS concentration in response to sulphate deprivation. The observed fluctuations of intracellular OAS concentrations, combined with the OAS dissociation constant and the catalytic properties of OAS-TL, support the model of a dynamic cysteine synthesis system with regulatory function as can be expected from the position of the reaction in the sulphur assimilation pathway.

Age estimation of the Deccan Traps from the North American apparent polar wander path

NASA Technical Reports Server (NTRS)

Stoddard, Paul R.; Jurdy, Donna M.

1988-01-01

It has recently been proposed that flood basalt events, such as the eruption of the Deccan Traps, have been responsible for mass extinctions. To test this hypothesis, accurate estimations of the ages and duration of these events are needed. In the case of the Deccan Traps, however, neither age nor duration of emplacement is well constrianed; measured ages range from 40 to more than 80 Myr, and estimates of duration range from less than 1 to 67 Myr. To make an independent age determination, paleomagnetic and sea-floor-spreading data are used, and the associated errors are estimated. The Deccan paleomagnetic pole is compared with the reference apparent polar wander path of North America by rotating the positions of the paleomagnetic pole for the Deccan Traps to the reference path for a range of assumed ages. Uncertainties in the apparent polar wander path, Deccan paleopole position, and errors resulting from the plate reconstruction are estimated. It is suggested that 83-70 Myr is the most likely time of extrusion of these volcanic rocks.

Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications.

PubMed

Mordang, Jan-Jurre; Gubern-Mérida, Albert; den Heeten, Gerard; Karssemeijer, Nico

2016-04-01

In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists' detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performance of the CADe system in finding malignant microcalcifications. A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity range of 0.8-1.0 were significantly different between the system without BACs removal and the system with BACs removal, 0.129 ± 0.009 versus 0.144 ± 0.008 (p<0.05), respectively. Additionally, the sensitivity at one false positive per 50 cases and one false positive per 25 cases increased as well, 37% versus 51% (p<0.05) and 58% versus 67% (p<0.05) sensitivity, respectively. Additionally, the CADe system with BACs removal reduces the number of false positives per case by 29% on average. The same sensitivity at one false positive per 50 cases in the CADe system without BACs removal can be achieved at one false positive per 80 cases in the CADe system with BACs removal. By using dedicated algorithms to detect and remove breast arterial calcifications, the performance of CADe systems can be improved, in particular, at false positive rates representative for operating points used in screening.

Self-Government as a System of Education (1931)

ERIC Educational Resources Information Center

Carillo, Francisco

2011-01-01

One of the most important problems in education is that of inculcating a sense of citizenship. Most of the social and political disturbances in the world are due to the failure to perform duties and the false interpretation of rights--both apparently the outcome of ignorance. For that reason, it is most important that children should be accustomed…

39 CFR 946.4 - Disposition of property of unknown owners.

Code of Federal Regulations, 2010 CFR

2010-07-01

... DISPOSITION OF STOLEN MAIL MATTER AND PROPERTY ACQUIRED BY THE POSTAL INSPECTION SERVICE FOR USE AS EVIDENCE § 946.4 Disposition of property of unknown owners. (a) Where no apparent owner of property subject to... 39 Postal Service 1 2010-07-01 2010-07-01 false Disposition of property of unknown owners. 946.4...

39 CFR 946.4 - Disposition of property of unknown owners.

Code of Federal Regulations, 2011 CFR

2011-07-01

... DISPOSITION OF STOLEN MAIL MATTER AND PROPERTY ACQUIRED BY THE POSTAL INSPECTION SERVICE FOR USE AS EVIDENCE § 946.4 Disposition of property of unknown owners. (a) Where no apparent owner of property subject to... 39 Postal Service 1 2011-07-01 2011-07-01 false Disposition of property of unknown owners. 946.4...

Effects of depressive disorder on false memory for emotional information.

PubMed

Yeh, Zai-Ting; Hua, Mau-Sun

2009-01-01

This study explored with a false memory paradigm whether (1) depressed patients revealed more false memories and (2) whether more negative false than positive false recognition existed in subjects with depressive disorders. Thirty-two patients suffering from a major depressive episode (DSM-IV criteria), and 30 age- and education-matched normal control subjects participated in this study. After the presentation of a list of positive, negative, and neutral association items in the learning phase, subjects were asked to give a yes/no response in the recognition phase. They were also asked to rate 81 recognition items with emotional valence scores. The results revealed more negative false memories in the clinical depression group than in the normal control group; however, we did not find more negative false memories than positive ones in patients. When compared with the normal group, a more conservative response criterion for positive items was evident in patient groups. It was also found that when compared with the normal group, the subjects in the depression group perceived the positive items as less positive. On the basis of present results, it is suggested that depressed subjects judged the emotional information with criteria different from normal individuals, and patients' emotional memory intensity is attenuated by their mood.

Commercial radioimmunoassay for beta subunit of human chorionic gonadotropin: falsely positive determinations due to elevated serum luteinizing hormone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, J.E. Jr.; Platoff, G.E.; Kubrock, C.A.

1982-01-01

Among 17 men who had received seemingly curative treatment for unilateral non-seminomatous germ cell tumors for the testis and who had consistently normal serum human chorionic gonadotropin (HCG) levels at a reference laboratory, 7 (41%) had at least one falsely positive commercial serum HCG determination. To investigate the cause of these falsely positive determinations the authors measured the cross reactivity of luteinizing hormone (LH) and follicle stimulating hormone (FSH) standards in the commercial HCG assay, and studied the relationships between commercial HCG levels and serum LH levels, serum FSH levels and gonadal status in men with and without normal gonadalmore » function. The falsely positive HCG determinations appeared to be due to elevated serum LH levels and cross reactivity of LH in the commercial HCG assay because: 1) there was substantial cross reactivity of the LH standards in the commercial assay, 2) the serum LH was elevated in four of six men with solitary testes, 3) there was a striking correlation between elevated serum LH levels and falsely elevated commercial HCG levels in ten men with solitary or absent testes, and 4) there were no falsely positive HCG determinations in 13 normal men but there were falsely positive HCG determinations in seven of ten anorchid men.« less

The efficacy and cost of alternative strategies for systematic screening for type 2 diabetes in the U.S. population 45-74 years of age.

PubMed

Johnson, Susan L; Tabaei, Bahman P; Herman, William H

2005-02-01

To simulate the outcomes of alternative strategies for screening the U.S. population 45-74 years of age for type 2 diabetes. We simulated screening with random plasma glucose (RPG) and cut points of 100, 130, and 160 mg/dl and a multivariate equation including RPG and other variables. Over 15 years, we simulated screening at intervals of 1, 3, and 5 years. All positive screening tests were followed by a diagnostic fasting plasma glucose or an oral glucose tolerance test. Outcomes include the numbers of false-negative, true-positive, and false-positive screening tests and the direct and indirect costs. At year 15, screening every 3 years with an RPG cut point of 100 mg/dl left 0.2 million false negatives, an RPG of 130 mg/dl or the equation left 1.3 million false negatives, and an RPG of 160 mg/dl left 2.8 million false negatives. Over 15 years, the absolute difference between the most sensitive and most specific screening strategy was 4.5 million true positives and 476 million false-positives. Strategies using RPG cut points of 130 mg/dl or the multivariate equation every 3 years identified 17.3 million true positives; however, the equation identified fewer false-positives. The total cost of the most sensitive screening strategy was $42.7 billion and that of the most specific strategy was $6.9 billion. Screening for type 2 diabetes every 3 years with an RPG cut point of 130 mg/dl or the multivariate equation provides good yield and minimizes false-positive screening tests and costs.

Breast cancer detection risk in screening mammography after a false-positive result.

PubMed

Castells, X; Román, M; Romero, A; Blanch, J; Zubizarreta, R; Ascunce, N; Salas, D; Burón, A; Sala, M

2013-02-01

False-positives are a major concern in breast cancer screening. However, false-positives have been little evaluated as a prognostic factor for cancer detection. Our aim was to evaluate the association of false-positive results with the cancer detection risk in subsequent screening participations over a 17-year period. This is a retrospective cohort study of 762,506 women aged 45-69 years, with at least two screening participations, who underwent 2,594,146 screening mammograms from 1990 to 2006. Multilevel discrete-time hazard models were used to estimate the adjusted odds ratios (OR) of breast cancer detection in subsequent screening participations in women with false-positive results. False-positives involving a fine-needle aspiration cytology or a biopsy had a higher cancer detection risk than those involving additional imaging procedures alone (OR = 2.69; 95%CI: 2.28-3.16 and OR = 1.81; 95%CI: 1.70-1.94, respectively). The risk of cancer detection increased substantially if women with cytology or biopsy had a familial history of breast cancer (OR = 4.64; 95%CI: 3.23-6.66). Other factors associated with an increased cancer detection risk were age 65-69 years (OR = 1.84; 95%CI: 1.67-2.03), non-attendance at the previous screening invitation (OR = 1.26; 95%CI: 1.11-1.43), and having undergone a previous benign biopsy outside the screening program (OR = 1.24; 95%CI: 1.13-1.35). Women with a false-positive test have an increased risk of cancer detection in subsequent screening participations, especially those with a false-positive result involving cytology or biopsy. Understanding the factors behind this association could provide valuable information to increase the effectiveness of breast cancer screening. Copyright © 2012 Elsevier Ltd. All rights reserved.

Psychological distress in U.S. women who have experienced false-positive mammograms.

PubMed

Jatoi, Ismail; Zhu, Kangmin; Shah, Mona; Lawrence, William

2006-11-01

In the United States, approximately 10.7% of all screening mammograms lead to a false-positive result, but the overall impact of false-positives on psychological well-being is poorly understood. Data were analyzed from the 2000 U.S. National Health Interview Survey (NHIS), the most recent national survey that included a cancer control module. Study subjects were 9,755 women who ever had a mammogram, of which 1,450 had experienced a false-positive result. Psychological distress was assessed using the validated K6 questionnaire and logistic regression was used to discern any association with previous false-positive mammograms. In a multivariate analysis, women who had indicated a previous false-positive mammogram were more likely to report feeling sad (OR = 1.18, 95% CI, 1.03-1.35), restless (OR = 1.23, 95% CI, 1.08-1.40), worthless (OR = 1.27, 95% CI, 1.04-1.54), and finding that everything was an effort (OR = 1.27, 95% CI, 1.10-1.47). These women were also more likely to have seen a mental health professional in the 12 months preceding the survey (OR = 1.28, 95% CI, 1.03-1.58) and had a higher composite score on all items of the K6 scale (P < 0.0001), a reflection of increased psychological distress. Analyses by age and race revealed that, among women who had experienced false-positives, younger women were more likely to feel that everything was an effort, and blacks were more likely to feel restless. In a random sampling of the U.S. population, women who had previously experienced false-positive mammograms were more likely to report symptoms of anxiety and depression.

False Positive Probabilities for all Kepler Objects of Interest: 1284 Newly Validated Planets and 428 Likely False Positives

NASA Astrophysics Data System (ADS)

Morton, Timothy D.; Bryson, Stephen T.; Coughlin, Jeffrey L.; Rowe, Jason F.; Ravichandran, Ganesh; Petigura, Erik A.; Haas, Michael R.; Batalha, Natalie M.

2016-05-01

We present astrophysical false positive probability calculations for every Kepler Object of Interest (KOI)—the first large-scale demonstration of a fully automated transiting planet validation procedure. Out of 7056 KOIs, we determine that 1935 have probabilities <1% of being astrophysical false positives, and thus may be considered validated planets. Of these, 1284 have not yet been validated or confirmed by other methods. In addition, we identify 428 KOIs that are likely to be false positives, but have not yet been identified as such, though some of these may be a result of unidentified transit timing variations. A side product of these calculations is full stellar property posterior samplings for every host star, modeled as single, binary, and triple systems. These calculations use vespa, a publicly available Python package that is able to be easily applied to any transiting exoplanet candidate.

Predictive model of outcome of targeted nodal assessment in colorectal cancer.

PubMed

Nissan, Aviram; Protic, Mladjan; Bilchik, Anton; Eberhardt, John; Peoples, George E; Stojadinovic, Alexander

2010-02-01

Improvement in staging accuracy is the principal aim of targeted nodal assessment in colorectal carcinoma. Technical factors independently predictive of false negative (FN) sentinel lymph node (SLN) mapping should be identified to facilitate operative decision making. To define independent predictors of FN SLN mapping and to develop a predictive model that could support surgical decisions. Data was analyzed from 2 completed prospective clinical trials involving 278 patients with colorectal carcinoma undergoing SLN mapping. Clinical outcome of interest was FN SLN(s), defined as one(s) with no apparent tumor cells in the presence of non-SLN metastases. To assess the independent predictive effect of a covariate for a nominal response (FN SLN), a logistic regression model was constructed and parameters estimated using maximum likelihood. A probabilistic Bayesian model was also trained and cross validated using 10-fold train-and-test sets to predict FN SLN mapping. Area under the curve (AUC) from receiver operating characteristics curves of these predictions was calculated to determine the predictive value of the model. Number of SLNs (<3; P = 0.03) and tumor-replaced nodes (P < 0.01) independently predicted FN SLN. Cross validation of the model created with Bayesian Network Analysis effectively predicted FN SLN (area under the curve = 0.84-0.86). The positive and negative predictive values of the model are 83% and 97%, respectively. This study supports a minimum threshold of 3 nodes for targeted nodal assessment in colorectal cancer, and establishes sufficient basis to conclude that SLN mapping and biopsy cannot be justified in the presence of clinically apparent tumor-replaced nodes.

Evaluation of MTANNs for eliminating false-positive with different computer aided pulmonary nodules detection software.

PubMed

Shi, Zhenghao; Ma, Jiejue; Feng, Yaning; He, Lifeng; Suzuki, Kenji

2015-11-01

MTANN (Massive Training Artificial Neural Network) is a promising tool, which applied to eliminate false-positive for thoracic CT in recent years. In order to evaluate whether this method is feasible to eliminate false-positive of different CAD schemes, especially, when it is applied to commercial CAD software, this paper evaluate the performance of the method for eliminating false-positives produced by three different versions of commercial CAD software for lung nodules detection in chest radiographs. Experimental results demonstrate that the approach is useful in reducing FPs for different computer aided lung nodules detection software in chest radiographs.

Computerized mass detection in whole breast ultrasound images: reduction of false positives using bilateral subtraction technique

NASA Astrophysics Data System (ADS)

Ikedo, Yuji; Fukuoka, Daisuke; Hara, Takeshi; Fujita, Hiroshi; Takada, Etsuo; Endo, Tokiko; Morita, Takako

2007-03-01

The comparison of left and right mammograms is a common technique used by radiologists for the detection and diagnosis of masses. In mammography, computer-aided detection (CAD) schemes using bilateral subtraction technique have been reported. However, in breast ultrasonography, there are no reports on CAD schemes using comparison of left and right breasts. In this study, we propose a scheme of false positive reduction based on bilateral subtraction technique in whole breast ultrasound images. Mass candidate regions are detected by using the information of edge directions. Bilateral breast images are registered with reference to the nipple positions and skin lines. A false positive region is detected based on a comparison of the average gray values of a mass candidate region and a region with the same position and same size as the candidate region in the contralateral breast. In evaluating the effectiveness of the false positive reduction method, three normal and three abnormal bilateral pairs of whole breast images were employed. These abnormal breasts included six masses larger than 5 mm in diameter. The sensitivity was 83% (5/6) with 13.8 (165/12) false positives per breast before applying the proposed reduction method. By applying the method, false positives were reduced to 4.5 (54/12) per breast without removing a true positive region. This preliminary study indicates that the bilateral subtraction technique is effective for improving the performance of a CAD scheme in whole breast ultrasound images.

Evaluation of fecal elastase and serum cholecystokinin in dogs with a false positive fecal elastase test.

PubMed

Steiner, J M; Rehfeld, J F; Pantchev, N

2010-01-01

An assay for the measurement of pancreatic elastase in dog feces has been introduced. The goal of this study was to evaluate the rate of false-positive fecal-elastase test results in dogs with suspected exocrine pancreatic insufficiency (EPI) and to assess serum cholecystokinin (CCK) concentrations in dogs with a false positive fecal elastase test result. Twenty-six fecal and serum samples from dogs suspected of EPI, for which samples had been submitted to a commercial laboratory (Vet Med Labor) for analysis. Prospective study. Serum trypsin-like immunoreactivity (TLI) was measured in 26 dogs with a decreased fecal elastase concentration of <10 microg/g feces. Serum CCK concentrations were measured in 21 of these dogs. Of 26 dogs with a decreased fecal elastase concentration, 6 (23%) had serum TLI concentrations within or above the reference range. Serum CCK concentrations were significantly higher in dogs with a true positive fecal elastase test result (median: 1.1 pmol/L; range: 0.1-3.3 pmol/L) than in those with a false positive fecal elastase test result (median: 0.1 pmol/L; range: 0.1-0.9 pmol/L; P value = .0163). The rate of false positive fecal elastase test results was high in this group of dogs, suggesting that diagnosis of EPI must be confirmed by other means. The decreased CCK concentration in dogs with a false positive fecal elastase test result could suggest that false positive results are because of decreased stimulation of exocrine pancreatic function caused by other conditions.

Sherlock Holmes and child psychopathology assessment approaches: the case of the false-positive.

PubMed

Jensen, P S; Watanabe, H

1999-02-01

To explore the relative value of various methods of assessing childhood psychopathology, the authors compared 4 groups of children: those who met criteria for one or more DSM diagnoses and scored high on parent symptom checklists, those who met psychopathology criteria on either one of these two assessment approaches alone, and those who met no psychopathology assessment criterion. Parents of 201 children completed the Child Behavior Checklist (CBCL), after which children and parents were administered the Diagnostic Interview Schedule for Children (version 2.1). Children and parents also completed other survey measures and symptom report inventories. The 4 groups of children were compared against "external validators" to examine the merits of "false-positive" and "false-negative" cases. True-positive cases (those that met DSM criteria and scored high on the CBCL) differed significantly from the true-negative cases on most external validators. "False-positive" and "false-negative" cases had intermediate levels of most risk factors and external validators. "False-positive" cases were not normal per se because they scored significantly above the true-negative group on a number of risk factors and external validators. A similar but less marked pattern was noted for "false-negatives." Findings call into question whether cases with high symptom checklist scores despite no formal diagnoses should be considered "false-positive." Pending the availability of robust markers for mental illness, researchers and clinicians must resist the tendency to reify diagnostic categories or to engage in arcane debates about the superiority of one assessment approach over another.

Characterization of Actinides Complexed to Nuclear Fuel Constituents Using ESI-MS

DOE PAGES

McDonald, Luther W.; Campbell, James A.; Vercouter, Thomas; ...

2016-03-01

Electrospray ionization-mass spectrometry (ESI-MS) was tested for its use in monitoring spent nuclear fuel (SNF) constituents including U, Pu, dibutyl phosphate (DBP), and tributyl phosphate (TBP). Both positive and negative ion modes were used to evaluate the speciation of U and Pu with TBP and DBP. Furthermore, apparent stability constants were determined for U complexed to TBP and DBP. In positive ion mode, TBP produced a strong signal with and without complexation to U or Pu, but, in negative ion mode, no TBP, U-TBP, or Pu-TBP complexes were observed. Apparent stability constants were determined for [UO 2(NO 3) 2(TBP) 2],more » [UO 2(NO 3) 2(H 2O)(TBP) 2], and [UO 2(NO 3) 2(TBP) 3]. In contrast DBP, U-DBP, and Pu-DBP complexes were observed in both positive and negative ion modes. Apparent stability constants were determined for the species [UO 2(DBP)], [UO 2(DBP) 3], and [UO 2(DBP) 4]. Analyzing mixtures of U or Pu with TBP and DBP yielded the formation of ternary complexes whose stoichiometry was directly related to the ratio of TBP to DBP. The ESI-MS protocols used in this study will further demonstrate the utility of ESI-MS and its applicability to process control monitoring in SNF reprocessing facilities.« less

Retrospective imaging study on the diagnosis of pathological false positive iodine-131 scans in patients with thyroid cancer.

PubMed

Jia, Qiang; Meng, Zhaowei; Tan, Jian; Zhang, Guizhi; He, Yajing; Sun, Haoran; Yu, Chunshui; Li, Dong; Zheng, Wei; Wang, Renfei; Wang, Shen; Li, Xue; Zhang, Jianping; Hu, Tianpeng; Liu, N A; Upadhyaya, Arun

2015-11-01

Iodine-131 (I-131) therapy and post-therapy I-131 scanning are essential in the management of differentiated thyroid cancer (DTC). However, pathological false positive I-131 scans can lead to misdiagnosis and inappropriate I-131 treatment. This retrospective study aimed to investigate the best imaging modality for the diagnosis of pathological false positive I-131 scans in a DTC patient cohort, and to determine its incidence. DTC patient data archived from January 2008 to January 2010 was retrieved. Post-therapeutic I-131 scans were conducted and interpreted. The imaging modalities of magnetic resonance imaging (MRI), computed tomography and ultrasonography were applied and compared to check all suspected lesions. Biopsy or needle aspiration was conducted for patients who consented to the acquisition of histopathological confirmation. Data for 156 DTC patients were retrieved. Only 6 cases of pathological false-positives were found among these (incidence, 3.85%), which included 3 cases of thymic hyperplasia in the mediastinum, 1 case of pleomorphic adenoma in the parapharyngeal space and 1 case of thyroglossal duct cyst in the neck. MRI was demonstrated as the best imaging modality for diagnosis due to its superior soft tissue resolution. However, no imaging modality was able to identify the abdominal false positive-lesions observed in 2 cases, one of whom also had thymic hyperplasia. In conclusion, pathological false positive I-131 scans occurred with an incidence of 3.85%. MRI was the best imaging modality for diagnosing these pathological false-positives.

Variation in false-positive rates of mammography reading among 1067 radiologists: a population-based assessment.

PubMed

Tan, Alai; Freeman, Daniel H; Goodwin, James S; Freeman, Jean L

2006-12-01

The accuracy of mammography reading varies among radiologists. We conducted a population-based assessment on radiologist variation in false- positive rates of screening mammography and its associated radiologist characteristics. About 27,394 screening mammograms interpreted by 1067 radiologists were identified from a 5% non-cancer sample of Medicare claims during 1998-1999. The data were linked to the American Medical Association Masterfile to obtain radiologist characteristics. Multilevel logistic regression models were used to examine the radiologist variation in false-positive rates of screening mammography and the associated radiologist characteristics. Radiologists varied substantially in the false-positive rates of screening mammography (ranging from 1.5 to 24.1%, adjusting for patient characteristics). A longer time period since graduation is associated with lower false-positive rates (odds ratio [OR] for every 10 years increase: 0.87, 95% Confidence Interval [CI], 0.81-0.94) and female radiologists had higher false-positive rates than male radiologists (OR = 1.25, 95% CI, 1.05-1.49), adjusting for patient and other radiologist characteristics. The unmeasured factors contributed to about 90% of the between-radiologist variance. Radiologists varied greatly in accuracy of mammography reading. Female and more recently trained radiologists had higher false-positive rates. The variation among radiologists was largely due to unmeasured factors, especially unmeasured radiologist factors. If our results are confirmed in further studies, they suggest that system-level interventions would be required to reduce variation in mammography interpretation.

Is it time to sound an alarm about false-positive cell-free DNA testing for fetal aneuploidy?

PubMed

Mennuti, Michael T; Cherry, Athena M; Morrissette, Jennifer J D; Dugoff, Lorraine

2013-11-01

Testing cell-free DNA (cfDNA) in maternal blood samples has been shown to have very high sensitivity for the detection of fetal aneuploidy with very low false-positive results in high-risk patients who undergo invasive prenatal diagnosis. Recent observation in clinical practice of several cases of positive cfDNA tests for trisomy 18 and trisomy 13, which were not confirmed by cytogenetic testing of the pregnancy, may reflect a limitation of the positive predictive value of this quantitative testing, particularly when it is used to detect rare aneuploidies. Analysis of a larger number of false-positive cases is needed to evaluate whether these observations reflect the positive predictive value that should be expected. Infrequently, mechanisms (such as low percentage mosaicism or confined placental mosaicism) might also lead to positive cfDNA testing that is not concordant with standard prenatal cytogenetic diagnosis. The need to explore these and other possible causes of false-positive cfDNA testing is exemplified by 2 of these cases. Additional evaluation of cfDNA testing in clinical practice and a mechanism for the systematic reporting of false-positive and false-negative cases will be important before this test is offered widely to the general population of low-risk obstetric patients. In the meantime, incorporating information about the positive predictive value in pretest counseling and in clinical laboratory reports is recommended. These experiences reinforce the importance of offering invasive testing to confirm cfDNA results before parental decision-making. Copyright © 2013 Mosby, Inc. All rights reserved.

False-positive findings in Cochrane meta-analyses with and without application of trial sequential analysis: an empirical review.

PubMed

Imberger, Georgina; Thorlund, Kristian; Gluud, Christian; Wetterslev, Jørn

2016-08-12

Many published meta-analyses are underpowered. We explored the role of trial sequential analysis (TSA) in assessing the reliability of conclusions in underpowered meta-analyses. We screened The Cochrane Database of Systematic Reviews and selected 100 meta-analyses with a binary outcome, a negative result and sufficient power. We defined a negative result as one where the 95% CI for the effect included 1.00, a positive result as one where the 95% CI did not include 1.00, and sufficient power as the required information size for 80% power, 5% type 1 error, relative risk reduction of 10% or number needed to treat of 100, and control event proportion and heterogeneity taken from the included studies. We re-conducted the meta-analyses, using conventional cumulative techniques, to measure how many false positives would have occurred if these meta-analyses had been updated after each new trial. For each false positive, we performed TSA, using three different approaches. We screened 4736 systematic reviews to find 100 meta-analyses that fulfilled our inclusion criteria. Using conventional cumulative meta-analysis, false positives were present in seven of the meta-analyses (7%, 95% CI 3% to 14%), occurring more than once in three. The total number of false positives was 14 and TSA prevented 13 of these (93%, 95% CI 68% to 98%). In a post hoc analysis, we found that Cochrane meta-analyses that are negative are 1.67 times more likely to be updated (95% CI 0.92 to 2.68) than those that are positive. We found false positives in 7% (95% CI 3% to 14%) of the included meta-analyses. Owing to limitations of external validity and to the decreased likelihood of updating positive meta-analyses, the true proportion of false positives in meta-analysis is probably higher. TSA prevented 93% of the false positives (95% CI 68% to 98%). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Working memory affects false memory production for emotional events.

PubMed

Mirandola, Chiara; Toffalini, Enrico; Ciriello, Alfonso; Cornoldi, Cesare

2017-01-01

Whereas a link between working memory (WM) and memory distortions has been demonstrated, its influence on emotional false memories is unclear. In two experiments, a verbal WM task and a false memory paradigm for negative, positive or neutral events were employed. In Experiment 1, we investigated individual differences in verbal WM and found that the interaction between valence and WM predicted false recognition, with negative and positive material protecting high WM individuals against false remembering; the beneficial effect of negative material disappeared in low WM participants. In Experiment 2, we lowered the WM capacity of half of the participants with a double task request, which led to an overall increase in false memories; furthermore, consistent with Experiment 1, the increase in negative false memories was larger than that of neutral or positive ones. It is concluded that WM plays a critical role in determining false memory production, specifically influencing the processing of negative material.

Seated Occupant Apparent Mass Characteristics Under Automotive Postures and Vertical Vibration

NASA Astrophysics Data System (ADS)

RAKHEJA, S.; HARU, I.; BOILEAU, P.-É.

2002-05-01

The biodynamic apparent mass response characteristics of 24 human subjects (12 males and 12 females) seated under representative automotive postures with hands-in-lap (passengers) and hands-on-steering wheel (drivers) are reported. The measurements were carried out under white noise vertical excitations of 0·25, 0·5 and 1·0m/s2r.m.s. acceleration magnitudes in the 0·5-40Hz frequency range and a track measured input (1·07m/s2). The measured data have been analyzed to study the effects of hands position, body mass, magnitude and type of vibration excitation, and feet position, on the biodynamic response expressed in terms of apparent mass. A comparison of the measured response of subjects assuming typical automotive postures involving inclined cushion, inclined backrest and full use of backrest support with data determined under different postural conditions and excitation levels revealed considerable differences. The biodynamic response of automobile occupants seated with hands in lap, peaks in the 6·5-8·6Hz frequency range, which is considerably higher than the reported range of fundamental frequencies (4·5-5Hz) in most other studies involving different experimental conditions. The peak magnitude tends to decrease considerably for the driving posture with hands-on-steering wheel, while a second peak in the 8-12 Hz range becomes more apparent for this posture. The results suggest that biodynamic response of occupants seated in automotive seats and subject to vertical vibration need to be characterized, as a minimum, by two distinct functions for passenger and driving postures. A higher body mass, in general, yields higher peak magnitude response and lower corresponding frequency for both postures. The strong dependence of the response on the body mass is further demonstrated by grouping the measured data into four different mass ranges: less than 60 kg, between 60·5 and 70 kg, between 70·5 and 80 kg, and above 80 kg. From the results, it is concluded that hands position and body mass have the most significant influence on the apparent mass response under automotive posture and vibration.

Evaluation of positive and false-positive results in syphilis screening of blood donors in Rio de Janeiro, Brazil.

PubMed

Sandes, V S; Silva, S G C; Motta, I J F; Velarde, L G C; de Castilho, S R

2017-06-01

We propose to analyse the positive and false-positive results of treponemal and nontreponemal tests in blood donors from Brazil and to evaluate possible factors associated with the results of treponemal tests. Treponemal tests have been used widely for syphilis screening in blood banks. The introduction of these tests in donor screening has caused an impact and a loss of donors who need to be assessed. This was a retrospective cross-sectional study of syphilis screening and confirmatory test results of blood donors that were obtained before and after adopting a chemiluminescent immunoassay (CLIA). A comparative analysis was performed using a second sample drawn from positive donors. The possible factors associated with CLIA-positive or CLIA-false-positive results were investigated in a subgroup. Statistical tests were used to compare the proportions and adjusted estimates of association. The reactivity rate increased from 1·01% (N = 28 158) to 2·66% (N = 25 577) after introducing the new test. Among Venereal Disease Research Laboratory (VDRL)- and CLIA-confirmed results, the false-positive rates were 40·5% (N = 180) and 37·4% (N = 359), respectively (P = 0·5266). Older donors (OR = 1·04; P = 0·0010) and donors with lower education levels (OR = 6·59; P = 0·0029) were associated with a higher risk of positivity for syphilis. CLIA represents an improvement in blood bank serological screening. However, its use in a healthy population appears to result in high rates of false positives. Identifying which characteristics can predict false positives, however, remains a challenge. © 2017 British Blood Transfusion Society.

False-positive cryptococcal antigen latex agglutination caused by disinfectants and soaps.

PubMed Central

Blevins, L B; Fenn, J; Segal, H; Newcomb-Gayman, P; Carroll, K C

1995-01-01

Five disinfectants or soaps were tested to determine if any could be responsible for false-positive results obtained with the Latex-Crypto Antigen Detection System kit (Immuno-Mycologics, Inc., Norman, Okla.). Three disinfectants or soaps (Derma soap, 7X, and Bacdown) produced false-positive agglutination after repeated washing of ring slides during testing of a known negative cerebrospinal fluid specimen. PMID:7650214

How pH, Temperature, and Time of Incubation Affect False-Positive Responses and Uncertainty of the LAL Gel-Clot Test.

PubMed

Lourenço, Felipe Rebello; Botelho, Túlia De Souza; Pinto, Terezinha De Jesus Andreoli

2012-01-01

The limulus amebocyte lysate (LAL) test is the simplest and most widely used procedure for detection of endotoxin in parenteral drugs. The LAL test demands optimal pH, ionic strength, temperature, and time of incubation. Slight changes in these parameters may increase the frequency of false-positive responses and the estimated uncertainty of the LAL test. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. LAL tests were performed in nominal conditions (37 °C, 60 min, and pH 7) and in different conditions of temperature (36 °C and 38 °C), time of incubation (58 and 62 min), and pH (6 and 8). Slight differences in pH increase the frequency of false-positive responses 5-fold (relative risk 5.0), resulting in an estimated of uncertainty 7.6%. Temperature and time of incubation affect the LAL test less, showing relative risks of 1.5 and 1.0, respectively. Estimated uncertainties in 36 °C or 38 °C temperatures and 58 or 62 min of incubation were found to be 2.0% and 1.0%, respectively. Simultaneous differences in these parameters significantly increase the frequency of false-positive responses. The limulus amebocyte lysate (LAL) gel-clot test is a simple test for detection of endotoxin from Gram-negative bacteria. The test is based on a gel formation when a certain amount of endotoxin is present; it is a pass/fail test. The LAL test requires optimal pH, ionic strength, temperature, and time of incubation. Slight difference in these parameters may increase the frequency of false-positive responses. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. We find that slight differences in pH increase the frequency of false-positive responses 5-fold. Temperature and time of incubation affect the LAL test less. Simultaneous differences in these parameters significantly increase the frequency of false-positive responses.

Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mordang, Jan-Jurre, E-mail: Jan-Jurre.Mordang@radboudumc.nl; Gubern-Mérida, Albert; Karssemeijer, Nico

Purpose: In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists’ detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performancemore » of the CADe system in finding malignant microcalcifications. Methods: A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. Results: The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity range of 0.8–1.0 were significantly different between the system without BACs removal and the system with BACs removal, 0.129 ± 0.009 versus 0.144 ± 0.008 (p<0.05), respectively. Additionally, the sensitivity at one false positive per 50 cases and one false positive per 25 cases increased as well, 37% versus 51% (p<0.05) and 58% versus 67% (p<0.05) sensitivity, respectively. Additionally, the CADe system with BACs removal reduces the number of false positives per case by 29% on average. The same sensitivity at one false positive per 50 cases in the CADe system without BACs removal can be achieved at one false positive per 80 cases in the CADe system with BACs removal. Conclusions: By using dedicated algorithms to detect and remove breast arterial calcifications, the performance of CADe systems can be improved, in particular, at false positive rates representative for operating points used in screening.« less

On the apparent positions of T Tauri stars in the H-R diagram

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenyon, S.J.; Hartmann, L.W.

1990-01-01

The spread in apparent luminosities of T Tauri stars caused by occultation and emission from protostellar disks is investigated. A random distribution of disk inclination angles, coupled with a plausible range of accretion rates, introduces a significant scatter in apparent luminosities for intrinsically identical stars. The observed dispersion of luminosities for K7-M1 Hayashi track stars thought to have disks in Taurus-Auriga is similar to predictions of the simple accretion disk model, which suggets that age determinations form many pre-main-sequence stars are uncertain. The results also suggest that Stahler's birthline for convective track pre-main-sequence stars may be located at slightly lowermore » luminosities than previously thought. 38 refs.« less

Pulmonary cestodiasis in a cynomolgus monkey (Macaca fascicularis).

PubMed

Guillot, L M; Green, L C

1992-04-01

Cestodiasis in primates has been noted historically to occur quite frequently, although tissue damage and clinical signs may or may not be apparent. Larval cestodes, such as hydatid cysts or cysticercus cysts, are known to cause extensive tissue damage, while other larval cestodes, such as tetrathyridia, cause minimal damage to the host. This case history concerns an apparently healthy cynomolgus monkey that was part of a surgical study. During the study, all parameters were normal. The monkey died 3 hours postsurgery. The apparent cause of death was respiratory arrest. At necropsy, it was discovered there were 1- to 3-mm-diameter cysts, which on transection extruded 2- to 5-mm-long larvae. The larvae could not be positively identified; however, they resembled tetrathyridia of Mesocestoides sp.

Motivation to hide emotion and children's understanding of the distinction between real and apparent emotions.

PubMed

Gosselin, Pierre; Warren, Madeleine; Diotte, Michèle

2002-12-01

The authors investigated the extent to which children's understanding of the distinction between real and apparent emotions varied according to the motivation to hide emotions. Children, aged 6-7 and 10-11 years, were read stories designed to elicit either prosocial or self-protective motivated display rules and were asked to predict the facial expressions the protagonists would make to hide felt emotions. Children were found to understand the distinction between real and apparent emotions very well, independently of the type of motivation. Contrary to predictions, boys understood this distinction better than did girls when the motivation to hide positive emotions was prosocial. Children perceived neutralization as the most appropriate strategy to hide felt emotions, followed by masking.

Is the firewall consistent? Gedanken experiments on black hole complementarity and firewall proposal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, Dong-il; Lee, Bum-Hoon; Yeom, Dong-han, E-mail: dongil.j.hwang@gmail.com, E-mail: bhl@sogang.ac.kr, E-mail: innocent.yeom@gmail.com

2013-01-01

In this paper, we discuss the black hole complementarity and the firewall proposal at length. Black hole complementarity is inevitable if we assume the following five things: unitarity, entropy-area formula, existence of an information observer, semi-classical quantum field theory for an asymptotic observer, and the general relativity for an in-falling observer. However, large N rescaling and the AMPS argument show that black hole complementarity is inconsistent. To salvage the basic philosophy of the black hole complementarity, AMPS introduced a firewall around the horizon. According to large N rescaling, the firewall should be located close to the apparent horizon. We investigatemore » the consistency of the firewall with the two critical conditions: the firewall should be near the time-like apparent horizon and it should not affect the future infinity. Concerning this, we have introduced a gravitational collapse with a false vacuum lump which can generate a spacetime structure with disconnected apparent horizons. This reveals a situation that there is a firewall outside of the event horizon, while the apparent horizon is absent. Therefore, the firewall, if it exists, not only does modify the general relativity for an in-falling observer, but also modify the semi-classical quantum field theory for an asymptotic observer.« less

Is the firewall consistent? Gedanken experiments on black hole complementarity and firewall proposal

NASA Astrophysics Data System (ADS)

Hwang, Dong-il; Lee, Bum-Hoon; Yeom, Dong-han

2013-01-01

In this paper, we discuss the black hole complementarity and the firewall proposal at length. Black hole complementarity is inevitable if we assume the following five things: unitarity, entropy-area formula, existence of an information observer, semi-classical quantum field theory for an asymptotic observer, and the general relativity for an in-falling observer. However, large N rescaling and the AMPS argument show that black hole complementarity is inconsistent. To salvage the basic philosophy of the black hole complementarity, AMPS introduced a firewall around the horizon. According to large N rescaling, the firewall should be located close to the apparent horizon. We investigate the consistency of the firewall with the two critical conditions: the firewall should be near the time-like apparent horizon and it should not affect the future infinity. Concerning this, we have introduced a gravitational collapse with a false vacuum lump which can generate a spacetime structure with disconnected apparent horizons. This reveals a situation that there is a firewall outside of the event horizon, while the apparent horizon is absent. Therefore, the firewall, if it exists, not only does modify the general relativity for an in-falling observer, but also modify the semi-classical quantum field theory for an asymptotic observer.

Accommodating Uncertainty in Prior Distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Picard, Richard Roy; Vander Wiel, Scott Alan

2017-01-19

A fundamental premise of Bayesian methodology is that a priori information is accurately summarized by a single, precisely de ned prior distribution. In many cases, especially involving informative priors, this premise is false, and the (mis)application of Bayes methods produces posterior quantities whose apparent precisions are highly misleading. We examine the implications of uncertainty in prior distributions, and present graphical methods for dealing with them.

Apparently low reproducibility of true differential expression discoveries in microarray studies.

PubMed

Zhang, Min; Yao, Chen; Guo, Zheng; Zou, Jinfeng; Zhang, Lin; Xiao, Hui; Wang, Dong; Yang, Da; Gong, Xue; Zhu, Jing; Li, Yanhui; Li, Xia

2008-09-15

Differentially expressed gene (DEG) lists detected from different microarray studies for a same disease are often highly inconsistent. Even in technical replicate tests using identical samples, DEG detection still shows very low reproducibility. It is often believed that current small microarray studies will largely introduce false discoveries. Based on a statistical model, we show that even in technical replicate tests using identical samples, it is highly likely that the selected DEG lists will be very inconsistent in the presence of small measurement variations. Therefore, the apparently low reproducibility of DEG detection from current technical replicate tests does not indicate low quality of microarray technology. We also demonstrate that heterogeneous biological variations existing in real cancer data will further reduce the overall reproducibility of DEG detection. Nevertheless, in small subsamples from both simulated and real data, the actual false discovery rate (FDR) for each DEG list tends to be low, suggesting that each separately determined list may comprise mostly true DEGs. Rather than simply counting the overlaps of the discovery lists from different studies for a complex disease, novel metrics are needed for evaluating the reproducibility of discoveries characterized with correlated molecular changes. Supplementaty information: Supplementary data are available at Bioinformatics online.

Reward positivity: Reward prediction error or salience prediction error?

PubMed

Heydari, Sepideh; Holroyd, Clay B

2016-08-01

The reward positivity is a component of the human ERP elicited by feedback stimuli in trial-and-error learning and guessing tasks. A prominent theory holds that the reward positivity reflects a reward prediction error signal that is sensitive to outcome valence, being larger for unexpected positive events relative to unexpected negative events (Holroyd & Coles, 2002). Although the theory has found substantial empirical support, most of these studies have utilized either monetary or performance feedback to test the hypothesis. However, in apparent contradiction to the theory, a recent study found that unexpected physical punishments also elicit the reward positivity (Talmi, Atkinson, & El-Deredy, 2013). The authors of this report argued that the reward positivity reflects a salience prediction error rather than a reward prediction error. To investigate this finding further, in the present study participants navigated a virtual T maze and received feedback on each trial under two conditions. In a reward condition, the feedback indicated that they would either receive a monetary reward or not and in a punishment condition the feedback indicated that they would receive a small shock or not. We found that the feedback stimuli elicited a typical reward positivity in the reward condition and an apparently delayed reward positivity in the punishment condition. Importantly, this signal was more positive to the stimuli that predicted the omission of a possible punishment relative to stimuli that predicted a forthcoming punishment, which is inconsistent with the salience hypothesis. © 2016 Society for Psychophysiological Research.

Bone marrow cells stained by azide-conjugated Alexa fluors in the absence of an alkyne label.

PubMed

Lin, Guiting; Ning, Hongxiu; Banie, Lia; Qiu, Xuefeng; Zhang, Haiyang; Lue, Tom F; Lin, Ching-Shwun

2012-09-01

Thymidine analog 5-ethynyl-2'-deoxyuridine (EdU) has recently been introduced as an alternative to 5-bromo-2-deoxyuridine (BrdU) for cell labeling and tracking. Incorporation of EdU into replicating DNA can be detected by azide-conjugated fluors (eg, Alexa-azide) through a Cu(i)-catalyzed click reaction between EdU's alkyne moiety and azide. While this cell labeling method has proven to be valuable for tracking transplanted stem cells in various tissues, we have found that some bone marrow cells could be stained by Alexa-azide in the absence of EdU label. In intact rat femoral bone marrow, ~3% of nucleated cells were false-positively stained, and in isolated bone marrow cells, ~13%. In contrast to true-positive stains, which localize in the nucleus, the false-positive stains were cytoplasmic. Furthermore, while true-positive staining requires Cu(i), false-positive staining does not. Reducing the click reaction time or reducing the Alexa-azide concentration failed to improve the distinction between true- and false-positive staining. Hematopoietic and mesenchymal stem cell markers CD34 and Stro-1 did not co-localize with the false-positively stained cells, and these cells' identity remains unknown.

Determining bovine viral diarrhea and infectious bovine rhinotracheitis infections in dairy cattle using precolostral blood.

PubMed

Baillargeon, Paul; Arango-Sabogal, Juan C; Wellemans, Vincent; Fecteau, Gilles

2017-04-01

The objective of this study was to determine if precolostral blood samples are useful to detect apparent fetal infections with bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses. A convenience sample of 317 sera from 50 Canadian herds was used in the study. Antibody level was measured using 2 commercial IBR and BVD ELISA kits. Precolostral status of sera was confirmed on 304 samples using serum gamma-glutamyl transferase activity. Postcolostral serum samples yielded a higher proportion of positive results to IBR (OR = 86; 95% CI: 17.8 to 415.7) and BVD (OR = 199.3; 95% CI: 41.7 to 952.3) than did precolostral samples. All positive precolostral serum samples ( n = 7 of 304) originated from calves born to vaccinated cows. Postcolostral positive serum samples ( n = 11 of 13) originated mostly (60%) from calves born to non-vaccinated cows. Precolostral serum sampling can detect apparent fetal infections in a herd.

The Illusion of the Positive: The impact of natural and induced mood on older adults’ false recall

PubMed Central

Emery, Lisa; Hess, Thomas M.; Elliot, Tonya

2012-01-01

Recent research suggests that affective and motivational processes can influence age differences in memory. In the current study, we examine the impact of both natural and induced mood state on age differences in false recall. Older and younger adults performed a version of the Deese-Roediger-McDermott (DRM; Roediger & McDermott, 1995) false memory paradigm in either their natural mood state or after a positive or negative mood induction. Results indicated that, after accounting for age differences in basic cognitive function, age-related differences in positive mood during the testing session were related to increased false recall in older adults. Inducing older adults into a positive mood also exacerbated age differences in false memory. In contrast, veridical recall did not appear to be systematically influenced by mood. Together, these results suggest that positive mood states can impact older adults’ information processing and potentially increase underlying cognitive age differences. PMID:22292431

The illusion of the positive: the impact of natural and induced mood on older adults' false recall.

PubMed

Emery, Lisa; Hess, Thomas M; Elliot, Tonya

2012-11-01

Recent research suggests that affective and motivational processes can influence age differences in memory. In the current study, we examine the impact of both natural and induced mood state on age differences in false recall. Older and younger adults performed a version of the Deese-Roediger-McDermott (DRM; Roediger & McDermott, 1995 , Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803) false memory paradigm in either their natural mood state or after a positive or negative mood induction. Results indicated that, after accounting for age differences in basic cognitive function, age-related differences in positive mood during the testing session were related to increased false recall in older adults. Inducing older adults into a positive mood also exacerbated age differences in false memory. In contrast, veridical recall did not appear to be systematically influenced by mood. Together, these results suggest that positive mood states can impact older adults' information processing and potentially increase underlying cognitive age differences.

Evaluation of the Architect HIV Ag/Ab Combo Assay in a low-prevalence setting: The role of samples with a low S/CO ratio.

PubMed

Alonso, Roberto; Pérez-García, Felipe; Gijón, Paloma; Collazos, Ana; Bouza, Emilio

2018-06-01

The Architect HIV Ag/Ab Combo Assay, a fourth-generation ELISA, has proven to be highly reliable for the diagnosis of HIV infection. However, its high sensitivity may lead to false-positive results. To evaluate the diagnostic performance of Architect in a low-prevalence population and to assess the role of the sample-to-cutoff ratio (S/CO) in reducing the frequency of false-positive results. We conducted a retrospective study of samples analyzed by Architect between January 2015 and June 2017. Positive samples were confirmed by immunoblot (RIBA) or nucleic acid amplification tests (NAATs). Different S/CO thresholds (1, 2.5, 10, 25, and 100) were analyzed to determine sensitivity, specificity, and negative and positive predictive values (NPV, PPV). ROC analysis was used to determine the optimal S/CO. A total of 69,471 samples were analyzed. 709 (1.02%) were positive by Architect. Of these, 63 (8.89%) were false-positive results. Most of them (93.65%) were in samples with S/CO < 100. However, most confirmations by NAATs (12 out of 19 cases) were also recorded for these samples. The optimal S/CO was 2.5, which provided the highest area under the ROC curve (0.9998) and no false-negative results. With this S/CO, sensitivity and specificity were 100.0%, and PPV and NPV were 95.8% and 100.0%, respectively. In addition, the frequency of false-positive results decreased significantly to 4.15%. Although Architect generates a relatively high number of false-positive results, raising the S/CO limit too much to increase specificity can lead to false-negative results, especially in newly infected individuals. Copyright © 2018 Elsevier B.V. All rights reserved.

Prehospital Acute ST-Elevation Myocardial Infarction Identification in San Diego: A Retrospective Analysis of the Effect of a New Software Algorithm.

PubMed

Coffey, Christanne; Serra, John; Goebel, Mat; Espinoza, Sarah; Castillo, Edward; Dunford, James

2018-05-03

A significant increase in false positive ST-elevation myocardial infarction (STEMI) electrocardiogram interpretations was noted after replacement of all of the City of San Diego's 110 monitor-defibrillator units with a new brand. These concerns were brought to the manufacturer and a revised interpretive algorithm was implemented. This study evaluated the effects of a revised interpretation algorithm to identify STEMI when used by San Diego paramedics. Data were reviewed 6 months before and 6 months after the introduction of a revised interpretation algorithm. True-positive and false-positive interpretations were identified. Factors contributing to an incorrect interpretation were assessed and patient demographics were collected. A total of 372 (234 preimplementation, 138 postimplementation) cases met inclusion criteria. There was a significant reduction in false positive STEMI (150 preimplementation, 40 postimplementation; p < 0.001) after implementation. The most common factors resulting in false positive before implementation were right bundle branch block, left bundle branch block, and atrial fibrillation. The new algorithm corrected for these misinterpretations with most postimplementation false positives attributed to benign early repolarization and poor data quality. Subsequent follow-up at 10 months showed maintenance of the observed reduction in false positives. This study shows that introducing a revised 12-lead interpretive algorithm resulted in a significant reduction in the number of false positive STEMI electrocardiogram interpretations in a large urban emergency medical services system. Rigorous testing and standardization of new interpretative software is recommended before introduction into a clinical setting to prevent issues resulting from inappropriate cardiac catheterization laboratory activations. Copyright © 2018 Elsevier Inc. All rights reserved.

True detection limits in an experimental linearly heteroscedastic system.. Part 2

NASA Astrophysics Data System (ADS)

Voigtman, Edward; Abraham, Kevin T.

2011-11-01

Despite much different processing of the experimental fluorescence detection data presented in Part 1, essentially the same estimates were obtained for the true theoretical Currie decision levels ( YC and XC) and true Currie detection limits ( YD and XD). The obtained experimental values, for 5% probability of false positives and 5% probability of false negatives, were YC = 56.0 mV, YD = 125. mV, XC = 0.132 μg/mL and XD = 0.293 μg/mL. For 5% probability of false positives and 1% probability of false negatives, the obtained detection limits were YD = 158 . mV and XD = 0.371 μg/mL. Furthermore, by using bootstrapping methodology on the experimental data for the standards and the analytical blank, it was possible to validate previously published experimental domain expressions for the decision levels ( yC and xC) and detection limits ( yD and xD). This was demonstrated by testing the generated decision levels and detection limits for their performance in regard to false positives and false negatives. In every case, the obtained numbers of false negatives and false positives were as specified a priori.

Interval Breast Cancer Rates and Histopathologic Tumor Characteristics after False-Positive Findings at Mammography in a Population-based Screening Program.

PubMed

Hofvind, Solveig; Sagstad, Silje; Sebuødegård, Sofie; Chen, Ying; Roman, Marta; Lee, Christoph I

2018-04-01

Purpose To compare rates and tumor characteristics of interval breast cancers (IBCs) detected after a negative versus false-positive screening among women participating in the Norwegian Breast Cancer Screening Program. Materials and Methods The Cancer Registry Regulation approved this retrospective study. Information about 423 445 women aged 49-71 years who underwent 789 481 full-field digital mammographic screening examinations during 2004-2012 was extracted from the Cancer Registry of Norway. Rates and odds ratios of IBC among women with a negative (the reference group) versus a false-positive screening were estimated by using logistic regression models adjusted for age at diagnosis and county of residence. Results A total of 1302 IBCs were diagnosed after 789 481 screening examinations, of which 7.0% (91 of 1302) were detected among women with a false-positive screening as the most recent breast imaging examination before detection. By using negative screening as the reference, adjusted odds ratios of IBCs were 3.3 (95% confidence interval [CI]: 2.6, 4.2) and 2.8 (95% CI: 1.8, 4.4) for women with a false-positive screening without and with needle biopsy, respectively. Women with a previous negative screening had a significantly lower proportion of tumors that were 10 mm or less (14.3% [150 of 1049] vs 50.0% [seven of 14], respectively; P < .01) and grade I tumors (13.2% [147 of 1114] vs 42.9% [six of 14]; P < .01), but a higher proportion of cases with lymph nodes positive for cancer (40.9% [442 of 1080] vs 13.3% [two of 15], respectively; P = .03) compared with women with a previous false-positive screening with benign biopsy. A retrospective review of the screening mammographic examinations identified 42.9% (39 of 91) of the false-positive cases to be the same lesion as the IBC. Conclusion By using a negative screening as the reference, a false-positive screening examination increased the risk of an IBC three-fold. The tumor characteristics of IBC after a negative screening were less favorable compared with those detected after a previous false-positive screening. © RSNA, 2017 Online supplemental material is available for this article.

Designing occupancy studies when false-positive detections occur

USGS Publications Warehouse

Clement, Matthew

2016-01-01

1.Recently, estimators have been developed to estimate occupancy probabilities when false-positive detections occur during presence-absence surveys. Some of these estimators combine different types of survey data to improve estimates of occupancy. With these estimators, there is a tradeoff between the number of sample units surveyed, and the number and type of surveys at each sample unit. Guidance on efficient design of studies when false positives occur is unavailable. 2.For a range of scenarios, I identified survey designs that minimized the mean square error of the estimate of occupancy. I considered an approach that uses one survey method and two observation states and an approach that uses two survey methods. For each approach, I used numerical methods to identify optimal survey designs when model assumptions were met and parameter values were correctly anticipated, when parameter values were not correctly anticipated, and when the assumption of no unmodelled detection heterogeneity was violated. 3.Under the approach with two observation states, false positive detections increased the number of recommended surveys, relative to standard occupancy models. If parameter values could not be anticipated, pessimism about detection probabilities avoided poor designs. Detection heterogeneity could require more or fewer repeat surveys, depending on parameter values. If model assumptions were met, the approach with two survey methods was inefficient. However, with poor anticipation of parameter values, with detection heterogeneity, or with removal sampling schemes, combining two survey methods could improve estimates of occupancy. 4.Ignoring false positives can yield biased parameter estimates, yet false positives greatly complicate the design of occupancy studies. Specific guidance for major types of false-positive occupancy models, and for two assumption violations common in field data, can conserve survey resources. This guidance can be used to design efficient monitoring programs and studies of species occurrence, species distribution, or habitat selection, when false positives occur during surveys.

Identification of Surprisingly Diverse Type IV Pili, across a Broad Range of Gram-Positive Bacteria

PubMed Central

Roos, David S.; Pohlschröder, Mechthild

2011-01-01

Background In Gram-negative bacteria, type IV pili (TFP) have long been known to play important roles in such diverse biological phenomena as surface adhesion, motility, and DNA transfer, with significant consequences for pathogenicity. More recently it became apparent that Gram-positive bacteria also express type IV pili; however, little is known about the diversity and abundance of these structures in Gram-positives. Computational tools for automated identification of type IV pilins are not currently available. Results To assess TFP diversity in Gram-positive bacteria and facilitate pilin identification, we compiled a comprehensive list of putative Gram-positive pilins encoded by operons containing highly conserved pilus biosynthetic genes (pilB, pilC). A surprisingly large number of species were found to contain multiple TFP operons (pil, com and/or tad). The N-terminal sequences of predicted pilins were exploited to develop PilFind, a rule-based algorithm for genome-wide identification of otherwise poorly conserved type IV pilins in any species, regardless of their association with TFP biosynthetic operons (http://signalfind.org). Using PilFind to scan 53 Gram-positive genomes (encoding >187,000 proteins), we identified 286 candidate pilins, including 214 in operons containing TFP biosynthetic genes (TBG+ operons). Although trained on Gram-positive pilins, PilFind identified 55 of 58 manually curated Gram-negative pilins in TBG+ operons, as well as 53 additional pilin candidates in operons lacking biosynthetic genes in ten species (>38,000 proteins), including 27 of 29 experimentally verified pilins. False positive rates appear to be low, as PilFind predicted only four pilin candidates in eleven bacterial species (>13,000 proteins) lacking TFP biosynthetic genes. Conclusions We have shown that Gram-positive bacteria contain a highly diverse set of type IV pili. PilFind can be an invaluable tool to study bacterial cellular processes known to involve type IV pilus-like structures. Its use in combination with other currently available computational tools should improve the accuracy of predicting the subcellular localization of bacterial proteins. PMID:22216142

A hybrid segmentation approach for geographic atrophy in fundus auto-fluorescence images for diagnosis of age-related macular degeneration.

PubMed

Lee, Noah; Laine, Andrew F; Smith, R Theodore

2007-01-01

Fundus auto-fluorescence (FAF) images with hypo-fluorescence indicate geographic atrophy (GA) of the retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). Manual quantification of GA is time consuming and prone to inter- and intra-observer variability. Automatic quantification is important for determining disease progression and facilitating clinical diagnosis of AMD. In this paper we describe a hybrid segmentation method for GA quantification by identifying hypo-fluorescent GA regions from other interfering retinal vessel structures. First, we employ background illumination correction exploiting a non-linear adaptive smoothing operator. Then, we use the level set framework to perform segmentation of hypo-fluorescent areas. Finally, we present an energy function combining morphological scale-space analysis with a geometric model-based approach to perform segmentation refinement of false positive hypo- fluorescent areas due to interfering retinal structures. The clinically apparent areas of hypo-fluorescence were drawn by an expert grader and compared on a pixel by pixel basis to our segmentation results. The mean sensitivity and specificity of the ROC analysis were 0.89 and 0.98%.

The Bacterial (Vibrio alginolyticus) Production of Tetrodotoxin in the Ribbon Worm Lineus longissimus—Just a False Positive?

PubMed Central

Strand, Malin; Hedström, Martin; Seth, Henrik; McEvoy, Eric G.; Jacobsson, Erik; Göransson, Ulf; Andersson, Håkan S.; Sundberg, Per

2016-01-01

We test previous claims that the bacteria Vibrio alginolyticus produces tetrodotoxin (TTX) when living in symbiosis with the nemertean Lineus longissimus by a setup with bacteria cultivation for TTX production. Toxicity experiments on the shore crab, Carcinus maenas, demonstrated the presence of a paralytic toxin, but evidence from LC-MS and electrophysiological measurements of voltage-gated sodium channel–dependent nerve conductance in male Wistar rat tissue showed conclusively that this effect did not originate from TTX. However, a compound of similar molecular weight was found, albeit apparently non-toxic, and with different LC retention time and MS/MS fragmentation pattern than those of TTX. We conclude that C. maenas paralysis and death likely emanate from a compound <5 kDa, and via a different mechanism of action than that of TTX. The similarity in mass between TTX and the Vibrio-produced low-molecular-weight, non-toxic compound invokes that thorough analysis is required when assessing TTX production. Based on our findings, we suggest that re-examination of some published claims of TTX production may be warranted. PMID:27023570

A statistical model of false negative and false positive detection of phase singularities.

PubMed

Jacquemet, Vincent

2017-10-01

The complexity of cardiac fibrillation dynamics can be assessed by analyzing the distribution of phase singularities (PSs) observed using mapping systems. Interelectrode distance, however, limits the accuracy of PS detection. To investigate in a theoretical framework the PS false negative and false positive rates in relation to the characteristics of the mapping system and fibrillation dynamics, we propose a statistical model of phase maps with controllable number and locations of PSs. In this model, phase maps are generated from randomly distributed PSs with physiologically-plausible directions of rotation. Noise and distortion of the phase are added. PSs are detected using topological charge contour integrals on regular grids of varying resolutions. Over 100 × 10 6 realizations of the random field process are used to estimate average false negative and false positive rates using a Monte-Carlo approach. The false detection rates are shown to depend on the average distance between neighboring PSs expressed in units of interelectrode distance, following approximately a power law with exponents in the range of 1.14 to 2 for false negatives and around 2.8 for false positives. In the presence of noise or distortion of phase, false detection rates at high resolution tend to a non-zero noise-dependent lower bound. This model provides an easy-to-implement tool for benchmarking PS detection algorithms over a broad range of configurations with multiple PSs.

False-positive IgM for CMV in pregnant women with autoimmune disease: a novel prognostic factor for poor pregnancy outcome.

PubMed

De Carolis, S; Santucci, S; Botta, A; Garofalo, S; Martino, C; Perrelli, A; Salvi, S; Degennaro, Va; de Belvis, Ag; Ferrazzani, S; Scambia, G

2010-06-01

Our aims were to assess the frequency of false-positive IgM antibodies for cytomegalovirus in pregnant women with autoimmune diseases and in healthy women (controls) and to determine their relationship with pregnancy outcome. Data from 133 pregnancies in 118 patients with autoimmune diseases and from 222 pregnancies in 198 controls were assessed. When positive IgM for cytomegalovirus was detected, IgG avidity, cytomegalovirus isolation and polymerase chain reaction for CMV-DNA in maternal urine and amniotic fluid samples were performed in order to identify primary infection or false positivity. A statistically significantly higher rate of false-positive IgM was found in pregnancies with autoimmune diseases (16.5%) in comparison with controls (0.9%). A worse pregnancy outcome was observed among patients with autoimmune disease and false cytomegalovirus IgM in comparison with those without false positivity: earlier week of delivery (p = 0.017), lower neonatal birth weight (p = 0.0004) and neonatal birth weight percentile (p = 0.002), higher rate of intrauterine growth restriction (p = 0.02) and babies weighing less than 2000 g (p = 0.025) were encountered. The presence of false cytomegalovirus IgM in patients with autoimmune diseases could be used as a novel prognostic index of poor pregnancy outcome: it may reflect a non-specific activation of the immune system that could negatively affect pregnancy outcome. Lupus (2010) 19, 844-849.

[Analysis of false-positive reaction for bacterial detection of blood samples with the automated microbial detection system BacT/ALERT 3D].

PubMed

Zhu, Li-Wei; Yang, Xue-Mei; Xu, Xiao-Qin; Xu, Jian; Lu, Huang-Jun; Yan, Li-Xing

2008-10-01

This study was aimed to analyze the results of false positive reaction in bacterial detection of blood samples with BacT/ALERT 3D system, to evaluate the specificity of this system, and to decrease the false positive reaction. Each reaction flasks in past five years were processed for bacteria isolation and identification. When the initial cultures were positive, the remaining samples and the corresponding units were recultured if still available. 11395 blood samples were detected. It is worthy of note that the incubator temperature should be stabilized, avoiding fluctuation; when the cultures were alarmed, the reaction flasks showed be kept some hours for further incubation so as to trace a sharply increasing signal to support the judgement of true bacterial growth. The results indicated that 122 samples (1.07%) wee positive at initial culture, out of them 107 samples (88.7%) were found bacterial, and 15 samples (12.3%) were found nothing. The detection curves of positive samples resulted from bacterial growth showed ascent. In conclusion, maintenance of temperature stability and avoidance of temperature fluctuation in incubator could decrease the occurrence of false-positive reaction in detection process. The reaction flasks with positive results at initial culture should be recultured, and whether existence of a sharply ascending logarilhimic growth phase in bacterial growth curve should be further detected, which are helpful to distinguish false-positive reactions from true positive, and thus increase the specificity of the BacT/ALERT system.

False-Positive Tuberculin Skin Test Results Among Low-Risk Healthcare Workers Following Implementation of Fifty-Dose Vials of Purified Protein Derivative.

PubMed

Collins, Jeffrey M; Hunter, Mary; Gordon, Wanda; Kempker, Russell R; Blumberg, Henry M; Ray, Susan M

2018-06-01

Following large declines in tuberculosis transmission the United States, large-scale screening programs targeting low-risk healthcare workers are increasingly a source of false-positive results. We report a large cluster of presumed false-positive tuberculin skin test results in healthcare workers following a change to 50-dose vials of Tubersol tuberculin.Infect Control Hosp Epidemiol 2018;39:750-752.

An Evaluation of Unit and ½ Mass Correction Approaches as a Means of Minimizing the False Positives Produced by M+2 species in US EPA Method 200.8 using ICP-MS

EPA Science Inventory

Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive ...

Algorithm of reducing the false positives in IDS based on correlation Analysis

NASA Astrophysics Data System (ADS)

Liu, Jianyi; Li, Sida; Zhang, Ru

2018-03-01

This paper proposes an algorithm of reducing the false positives in IDS based on correlation Analysis. Firstly, the algorithm analyzes the distinguishing characteristics of false positives and real alarms, and preliminary screen the false positives; then use the method of attribute similarity clustering to the alarms and further reduces the amount of alarms; finally, according to the characteristics of multi-step attack, associated it by the causal relationship. The paper also proposed a reverse causation algorithm based on the attack association method proposed by the predecessors, turning alarm information into a complete attack path. Experiments show that the algorithm simplifies the number of alarms, improve the efficiency of alarm processing, and contribute to attack purposes identification and alarm accuracy improvement.

Event-related Potentials Reveal Age Differences in the Encoding and Recognition of Scenes

PubMed Central

Gutchess, Angela H.; Ieuji, Yoko; Federmeier, Kara D.

2009-01-01

The present study used event-related potentials (ERPs) to investigate how the encoding and recognition of complex scenes change with normal aging. Although functional magnetic resonance imaging (fMRI) studies have identified more drastic age impairments at encoding than at recognition, ERP studies accumulate more evidence for age differences at retrieval. However, stimulus type and paradigm differences across the two literatures have made direct comparisons difficult. Here, we collected young and elderly adults’ encoding- and recognition-phase ERPs using the same materials and paradigm as a previous fMRI study. Twenty young and 20 elderly adults incidentally encoded and then recognized photographs of outdoor scenes. During encoding, young adults showed a frontocentral subsequent memory effect, with high-confidence hits exhibiting greater positivity than misses. Elderly adults showed a similar subsequent memory effect, which, however, did not differ as a function of confidence. During recognition, young adults elicited a widespread old/new effect, and high-confidence hits were distinct from both low-confidence hits and false alarms. Elderly adults elicited a smaller and later old/new effect, which was unaffected by confidence, and hits and false alarms were indistinguishable in the waveforms. Consistent with prior ERP work, these results point to important age-related changes in recognition-phase brain activity, even when behavioral measures of memory and confidence pattern similarly across groups. We speculate that memory processes with different time signatures contribute to the apparent differences across encoding and retrieval stages, and across methods. PMID:17583986

[Molecular beacon based PNA-FISH method combined with fluorescence scanning for rapid detection of Listeria monocytogenes].

PubMed

Wu, Shan; Zhang, Xiaofeng; Shuai, Jiangbing; Li, Ke; Yu, Huizhen; Jin, Chenchen

2016-07-04

To simplify the PNA-FISH (Peptide nucleic acid-fluorescence in situ hybridization) test, molecular beacon based PNA probe combined with fluorescence scanning detection technology was applied to replace the original microscope observation to detect Listeria monocytogenes The 5′ end and 3′ end of the L. monocytogenes specific PNA probes were labeled with the fluorescent group and the quenching group respectively, to form a molecular beacon based PNA probe. When PNA probe used for fluorescence scanning and N1 treatment as the control, the false positive rate was 11.4%, and the false negative rate was 0; when N2 treatment as the control, the false positive rate decreased to 4.3%, but the false negative rate rose to 18.6%. When beacon based PNA probe used for fluorescence scanning, taken N1 treatment as blank control, the false positive rate was 8.6%, and the false negative rate was 1.4%; taken N2 treatment as blank control, the false positive rate was 5.7%, and the false negative rate was 1.4%. Compared with PNA probe, molecular beacon based PNA probe can effectively reduce false positives and false negatives. The success rates of hybridization of the two PNA probes were 83.3% and 95.2% respectively; and the rates of the two beacon based PNA probes were 91.7% and 90.5% respectively, which indicated that labeling the both ends of the PNA probe dose not decrease the hybridization rate with the target bacteria. The combination of liquid phase PNA-FISH and fluorescence scanning method, can significantly improve the detection efficiency.

Implications of false-positive results for future cancer screenings.

PubMed

Taksler, Glen B; Keating, Nancy L; Rothberg, Michael B

2018-06-01

False-positive cancer screening results may affect a patient's willingness to obtain future screening. The authors conducted logistic regression analysis of 450,484 person-years of electronic medical records (2006-2015) in 92,405 individuals aged 50 to 75 years. Exposures were false-positive breast, prostate, or colorectal cancer screening test results (repeat breast imaging or negative breast biopsy ≤3 months after screening mammography, repeat prostate-specific antigen [PSA] test ≤3 months after PSA test result ≥4.0 ng/mL or negative prostate biopsy ≤3 months after any PSA result, or negative colonoscopy [without biopsy/polypectomy] ≤6 months after a positive fecal occult blood test). Outcomes were up-to-date status with breast or colorectal cancer screening. Covariates included prior screening history, clinical information (eg, family history, obesity, and smoking status), comorbidity, and demographics. Women were more likely to be up to date with breast cancer screening if they previously had false-positive mammography findings (adjusted odds ratio [AOR], 1.43 [95% confidence interval, 1.34-1.51] without breast biopsy and AOR, 2.02 [95% confidence interval, 1.56-2.62] with breast biopsy; both P<.001). The same women were more likely to be up to date with colorectal cancer screening (AOR range, 1.25-1.47 depending on breast biopsy; both P<.001). Men who previously had false-positive PSA testing were more likely to be up to date with colorectal cancer screening (AOR, 1.22 [P = .039] without prostate imaging/biopsy and AOR, 1.60 [P = .028] with imaging/biopsy). Results were stronger for individuals with more false-positive results (all P≤.005). However, women with previous false-positive colorectal cancer fecal occult blood test screening results were found to be less likely to be up to date with breast cancer screening (AOR, 0.73; P<.001). Patients who previously had a false-positive breast or prostate cancer screening test were more likely to engage in future screening. Cancer 2018;124:2390-8. © 2018 American Cancer Society. © 2018 American Cancer Society.

False-Positive Xpert MTB/RIF Results in Retested Patients with Previous Tuberculosis: Frequency, Profile, and Prospective Clinical Outcomes.

PubMed

Theron, Grant; Venter, Rouxjeane; Smith, Liezel; Esmail, Aliasgar; Randall, Philippa; Sood, Vishesh; Oelfese, Suzette; Calligaro, Greg; Warren, Robin; Dheda, Keertan

2018-03-01

Globally, Xpert MTB/RIF (Xpert) is the most widely used PCR test for the diagnosis of tuberculosis (TB). Positive results in previously treated patients, which are due to old DNA or active disease, are a diagnostic dilemma. We prospectively retested sputum from 238 patients, irrespective of current symptoms, who were previously diagnosed to be Xpert positive and treated successfully. Patients who retested as Xpert positive and culture negative were exhaustively investigated (repeat culture, chest radiography, bronchoscopy with bronchoalveolar lavage, long-term clinical follow-up). We evaluated whether the duration since previous treatment completion, mycobacterial burden (the Xpert cycle threshold [ C T ] value), and reclassification of Xpert-positive results with a very low semiquantitation level to Xpert-negative results reduced the rate of false positivity. A total of 229/238 (96%) of patients were culture negative. Sixteen of 229 (7%) were Xpert positive a median of 11 months (interquartile range, 5 to 19 months) after treatment completion. The specificity was 93% (95% confidence interval [CI], 89 to 96%). Nine of 15 (40%) Xpert-positive, culture-negative patients reverted to Xpert negative after 2 to 3 months (1 patient declined further participation). Patients with false-positive Xpert results had a lower mycobacterial burden than patients with true-positive Xpert results ( C T , 28.7 [95% CI, 27.2 to 30.4] versus 17.6 [95% CI, 16.9 to 18.2]; P < 0.001), an increased likelihood of a chest radiograph not compatible with active TB (5/15 patients versus 0/5 patients; P = 0.026), and less-viscous sputum (15/16 patients versus 2/5 patients whose sputum was graded as mucoid or less; P = 0.038). All patients who initially retested as Xpert positive and culture negative ("Xpert false positive") were clinically well without treatment after follow-up. The duration since the previous treatment poorly predicted false-positive results (a duration of ≤2 years identified only 66% of patients with false-positive results). Reclassifying Xpert-positive results with a very low semiquantitation level to Xpert negative improved the specificity (+3% [95% CI, +2 to +5%]) but reduced the sensitivity (-10% [95% CI, -4 to -15%]). Patients with previous TB retested with Xpert can have false-positive results and thus not require treatment. These data inform clinical practice by highlighting the challenges in interpreting Xpert-positive results, underscore the need for culture, and have implications for next-generation ultrasensitive tests. Copyright © 2018 American Society for Microbiology.

Three mechanisms model of shale gas in real state transport through a single nanopore

NASA Astrophysics Data System (ADS)

Li, Dongdong; Zhang, Yanyu; Sun, Xiaofei; Li, Peng; Zhao, Fengkai

2018-02-01

At present, the apparent permeability models of shale gas consider only the viscous flow and Knudsen diffusion of free gas, but do not take into account the influence of surface diffusion. Moreover, it is assumed that shale gas is in ideal state. In this paper, shale gas is assumed in real state, a new apparent permeability model for shale gas transport through a single nanopore is developed that captures many important migration mechanisms, such as viscous flow and Knudsen diffusion of free gas, surface diffusion of adsorbed gas. According to experimental data, the accuracy of apparent permeability model was verified. What’s more, the effects of pressure and pore radius on apparent permeability, and the effects on the permeability fraction of viscous flow, Knudsen diffusion and surface diffusion were analysed, separately. Finally, the results indicate that the error of the developed model in this paper was 3.02%, which is less than the existing models. Pressure and pore radius seriously affect the apparent permeability of shale gas. When the pore radius is small or pressure is low, the surface diffusion cannot be ignored. When the pressure and the pore radius is big, the viscous flow occupies the main position.

Case Reports of Aripiprazole Causing False-Positive Urine Amphetamine Drug Screens in Children.

PubMed

Kaplan, Justin; Shah, Pooja; Faley, Brian; Siegel, Mark E

2015-12-01

Urine drug screens (UDSs) are used to identify the presence of certain medications. One limitation of UDSs is the potential for false-positive results caused by cross-reactivity with other substances. Amphetamines have an extensive list of cross-reacting medications. The literature contains reports of false-positive amphetamine UDSs with multiple antidepressants and antipsychotics. We present 2 cases of presumed false-positive UDSs for amphetamines after ingestion of aripiprazole. Case 1 was a 16-month-old girl who accidently ingested 15 to 45 mg of aripiprazole. She was lethargic and ataxic at home with 1 episode of vomiting containing no identifiable tablets. She remained sluggish with periods of irritability and was admitted for observation. UDS on 2 consecutive days came back positive for amphetamines. Case 2 was of a 20-month-old girl who was brought into the hospital after accidental ingestion of an unknown quantity of her father's medications which included aripiprazole. UDS on the first day of admission came back positive only for amphetamines. Confirmatory testing with gas chromatography-mass spectrometry (GC-MS) on the blood and urine samples were also performed for both patients on presentation to detect amphetamines and were subsequently negative. Both patients returned to baseline and were discharged from the hospital. To our knowledge, these cases represent the first reports of false-positive amphetamine urine drug tests with aripiprazole. In both cases, aripiprazole was the drug with the highest likelihood of causing the positive amphetamine screen. The implications of these false-positives include the possibility of unnecessary treatment and monitoring of patients. Copyright © 2015 by the American Academy of Pediatrics.

The relationship between habitat characteristics and demographic performance of northern spotted owls in southern Oregon

USGS Publications Warehouse

Dugger, Katie M.; Wagner, Frank; Anthony, Robert G.; Olson, Gail S.

2005-01-01

We used data from Northern Spotted Owl (Strix occidentalis caurina) territories to model the effects of habitat (particularly intermediate-aged forest stand types), climate, and nonhabitat covariates (i.e., age, sex) on owl reproductive rate and apparent survival in southwestern Oregon. Our best model for reproductive rate included an interaction between a cyclic, annual time trend and male breeding experience, with higher reproductive rates in even years compared to odd, particularly for males with previous breeding experience. Reproductive rate was also negatively related to the amount of winter precipitation and positively related to the proportion of old-growth forest near the owl territory center. Apparent survival was not associated with age, sex, climate or any of the intermediate-aged forest types, but was positively associated with the proportion of older forest near the territory center in a pseudothreshold pattern. The quadratic structure of the proportion of nonhabitat farther from the nest or primary roost site was also part of our best survival model. Survival decreased dramatically when the amount of nonhabitat exceeded ∼50%. Habitat fitness potential estimates (λ̂h) for 97 owl territories ranged from 0.29–1.09, with a mean of 0.86 ± 0.02. Owl territories with habitat fitness potentials <1.0 were generally characterized by <40%–50% old forest habitat near the territory center. Our results indicate that both apparent survival and reproductive rate are positively associated with older forest types close to the nest or primary roost site. We found no support for either a positive or negative direct effect of intermediate-aged forests on either survival or reproductive rate.

Increased brain-predicted aging in treated HIV disease

PubMed Central

Underwood, Jonathan; Caan, Matthan W.A.; De Francesco, Davide; van Zoest, Rosan A.; Leech, Robert; Wit, Ferdinand W.N.M.; Portegies, Peter; Geurtsen, Gert J.; Schmand, Ben A.; Schim van der Loeff, Maarten F.; Franceschi, Claudio; Sabin, Caroline A.; Majoie, Charles B.L.M.; Winston, Alan; Reiss, Peter; Sharp, David J.

2017-01-01

Objective: To establish whether HIV disease is associated with abnormal levels of age-related brain atrophy, by estimating apparent brain age using neuroimaging and exploring whether these estimates related to HIV status, age, cognitive performance, and HIV-related clinical parameters. Methods: A large sample of virologically suppressed HIV-positive adults (n = 162, age 45–82 years) and highly comparable HIV-negative controls (n = 105) were recruited as part of the Comorbidity in Relation to AIDS (COBRA) collaboration. Using T1-weighted MRI scans, a machine-learning model of healthy brain aging was defined in an independent cohort (n = 2,001, aged 18–90 years). Neuroimaging data from HIV-positive and HIV-negative individuals were then used to estimate brain-predicted age; then brain-predicted age difference (brain-PAD = brain-predicted brain age − chronological age) scores were calculated. Neuropsychological and clinical assessments were also carried out. Results: HIV-positive individuals had greater brain-PAD score (mean ± SD 2.15 ± 7.79 years) compared to HIV-negative individuals (−0.87 ± 8.40 years; b = 3.48, p < 0.01). Increased brain-PAD score was associated with decreased performance in multiple cognitive domains (information processing speed, executive function, memory) and general cognitive performance across all participants. Brain-PAD score was not associated with age, duration of HIV infection, or other HIV-related measures. Conclusion: Increased apparent brain aging, predicted using neuroimaging, was observed in HIV-positive adults, despite effective viral suppression. Furthermore, the magnitude of increased apparent brain aging related to cognitive deficits. However, predicted brain age difference did not correlate with chronological age or duration of HIV infection, suggesting that HIV disease may accentuate rather than accelerate brain aging. PMID:28258081

Increased brain-predicted aging in treated HIV disease.

PubMed

Cole, James H; Underwood, Jonathan; Caan, Matthan W A; De Francesco, Davide; van Zoest, Rosan A; Leech, Robert; Wit, Ferdinand W N M; Portegies, Peter; Geurtsen, Gert J; Schmand, Ben A; Schim van der Loeff, Maarten F; Franceschi, Claudio; Sabin, Caroline A; Majoie, Charles B L M; Winston, Alan; Reiss, Peter; Sharp, David J

2017-04-04

To establish whether HIV disease is associated with abnormal levels of age-related brain atrophy, by estimating apparent brain age using neuroimaging and exploring whether these estimates related to HIV status, age, cognitive performance, and HIV-related clinical parameters. A large sample of virologically suppressed HIV-positive adults (n = 162, age 45-82 years) and highly comparable HIV-negative controls (n = 105) were recruited as part of the Comorbidity in Relation to AIDS (COBRA) collaboration. Using T1-weighted MRI scans, a machine-learning model of healthy brain aging was defined in an independent cohort (n = 2,001, aged 18-90 years). Neuroimaging data from HIV-positive and HIV-negative individuals were then used to estimate brain-predicted age; then brain-predicted age difference (brain-PAD = brain-predicted brain age - chronological age) scores were calculated. Neuropsychological and clinical assessments were also carried out. HIV-positive individuals had greater brain-PAD score (mean ± SD 2.15 ± 7.79 years) compared to HIV-negative individuals (-0.87 ± 8.40 years; b = 3.48, p < 0.01). Increased brain-PAD score was associated with decreased performance in multiple cognitive domains (information processing speed, executive function, memory) and general cognitive performance across all participants. Brain-PAD score was not associated with age, duration of HIV infection, or other HIV-related measures. Increased apparent brain aging, predicted using neuroimaging, was observed in HIV-positive adults, despite effective viral suppression. Furthermore, the magnitude of increased apparent brain aging related to cognitive deficits. However, predicted brain age difference did not correlate with chronological age or duration of HIV infection, suggesting that HIV disease may accentuate rather than accelerate brain aging. Copyright © 2017 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

Do Humans Have Two Systems to Track Beliefs and Belief-Like States?

ERIC Educational Resources Information Center

Apperly, Ian A.; Butterfill, Stephen A.

2009-01-01

The lack of consensus on how to characterize humans' capacity for belief reasoning has been brought into sharp focus by recent research. Children fail critical tests of belief reasoning before 3 to 4 years of age (H. Wellman, D. Cross, & J. Watson, 2001; H. Wimmer & J. Perner, 1983), yet infants apparently pass false-belief tasks at 13 or 15…

25 CFR 700.517 - Affiliations and financial interests.

Code of Federal Regulations, 2010 CFR

2010-04-01

... direct or indirect financial interest, which places them in a position of conflict or apparent conflict... for themselves, family members, or others if that information is not generally available to the public...

Effect of protocol-related variables and women's characteristics on the cumulative false-positive risk in breast cancer screening

PubMed Central

Román, R.; Sala, M.; Salas, D.; Ascunce, N.; Zubizarreta, R.; Castells, X.

2012-01-01

Background: Reducing the false-positive risk in breast cancer screening is important. We examined how the screening-protocol and women's characteristics affect the cumulative false-positive risk. Methods: This is a retrospective cohort study of 1 565 364 women aged 45–69 years who underwent 4 739 498 screening mammograms from 1990 to 2006. Multilevel discrete hazard models were used to estimate the cumulative false-positive risk over 10 sequential mammograms under different risk scenarios. Results: The factors affecting the false-positive risk for any procedure and for invasive procedures were double mammogram reading [odds ratio (OR) = 2.06 and 4.44, respectively], two mammographic views (OR = 0.77 and 1.56, respectively), digital mammography (OR = 0.83 for invasive procedures), premenopausal status (OR = 1.31 and 1.22, respectively), use of hormone replacement therapy (OR = 1.03 and 0.84, respectively), previous invasive procedures (OR = 1.52 and 2.00, respectively), and a familial history of breast cancer (OR = 1.18 and 1.21, respectively). The cumulative false-positive risk for women who started screening at age 50–51 was 20.39% [95% confidence interval (CI) 20.02–20.76], ranging from 51.43% to 7.47% in the highest and lowest risk profiles, respectively. The cumulative risk for invasive procedures was 1.76% (95% CI 1.66–1.87), ranging from 12.02% to 1.58%. Conclusions: The cumulative false-positive risk varied widely depending on the factors studied. These findings are relevant to provide women with accurate information and to improve the effectiveness of screening programs. PMID:21430183

Factors associated with a second deferral among donors eligible for re-entry after a false-positive screening test for syphilis, HCV, HBV and HIV.

PubMed

Grégoire, Y; Germain, M; Delage, G

2018-05-01

Since 25 May 2010, all donors at our blood centre who tested false-positive for HIV, HBV, HCV or syphilis are eligible for re-entry after further testing. Donors who have a second false-positive screening test, either during qualification for or after re-entry, are deferred for life. This study reports on factors associated with the occurrence of such deferrals. Rates of second false-positive results were compared by year of deferral, transmissible disease marker, gender, age, donor status (new or repeat) and testing platform (same or different) both at qualification for re-entry and afterwards. Chi-square tests were used to compare proportions. Cox regression was used for multivariate analyses. Participation rates in the re-entry programme were 42·1%: 25·6% failed to qualify for re-entry [different platform: 2·7%; same platform: 42·9% (P < 0·0001)]. After re-entry, rates of deferral for second false-positive results were 8·4% after 3 years [different platform: 1·8%; same platform: 21·4% (P < 0·0001)]. Deferral rates were higher for HIV and HCV than for HBV at qualification when tested on the same platform. The risk, when analysed by multivariate analyses, of a second deferral for a false-positive result, both at qualification and 3 years after re-entry, was lower for donors deferred on a different platform; this risk was higher for HIV, HCV and syphilis than for HBV and for new donors if tested on the same platform. Re-entry is more often successful when donors are tested on a testing platform different from the one on which they obtained their first false-positive result. © 2018 International Society of Blood Transfusion.

The probability of false positives in zero-dimensional analyses of one-dimensional kinematic, force and EMG trajectories.

PubMed

Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

2016-06-14

A false positive is the mistake of inferring an effect when none exists, and although α controls the false positive (Type I error) rate in classical hypothesis testing, a given α value is accurate only if the underlying model of randomness appropriately reflects experimentally observed variance. Hypotheses pertaining to one-dimensional (1D) (e.g. time-varying) biomechanical trajectories are most often tested using a traditional zero-dimensional (0D) Gaussian model of randomness, but variance in these datasets is clearly 1D. The purpose of this study was to determine the likelihood that analyzing smooth 1D data with a 0D model of variance will produce false positives. We first used random field theory (RFT) to predict the probability of false positives in 0D analyses. We then validated RFT predictions via numerical simulations of smooth Gaussian 1D trajectories. Results showed that, across a range of public kinematic, force/moment and EMG datasets, the median false positive rate was 0.382 and not the assumed α=0.05, even for a simple two-sample t test involving N=10 trajectories per group. The median false positive rate for experiments involving three-component vector trajectories was p=0.764. This rate increased to p=0.945 for two three-component vector trajectories, and to p=0.999 for six three-component vectors. This implies that experiments involving vector trajectories have a high probability of yielding 0D statistical significance when there is, in fact, no 1D effect. Either (a) explicit a priori identification of 0D variables or (b) adoption of 1D methods can more tightly control α. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of Technologies for Early Detection and Stratification of Breast Cancer

DTIC Science & Technology

2012-10-01

at the time of screening, and has an 8-10% false positive rate.3 These drawbacks lead to inaccurate patient diagnosis, which can allow potentially...95% recovery efficiency. Furthermore, using whole blood from healthy donors, we determined we have a zero false positive rate; that is, we have not...detected a single false positive event out of the dozen samples we ran. The technology we developed here is not only useful for the isolation of CTCs

An Evaluation of Unit and ½ Mass Correction Approaches as a Means of Minimizing the False Positives Produced by M+2 species in US EPA Method 200.8 using ICP-MS (webinar presentation)

EPA Science Inventory

Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive ...

Apparent ruminal synthesis of B vitamins in lactating dairy cows fed diets with different forage-to-concentrate ratios.

PubMed

Seck, M; Linton, J A Voelker; Allen, M S; Castagnino, D S; Chouinard, P Y; Girard, C L

2017-03-01

Effects of the forage-to-concentrate ratio on apparent ruminal synthesis of thiamine, riboflavin, niacin, vitamin B 6 , folates, and vitamin B 12 were evaluated in an experiment using 14 ruminally and duodenally cannulated Holstein cows. The experiment was a crossover design with two 15-d treatment periods and a 14-d preliminary period in which cows were fed a diet intermediate in composition between the treatment diets. Treatments were diets containing low-forage (44.8% forage, 32.8% starch, 24.4% neutral detergent fiber) or high-forage (61.4% forage, 22.5% starch, 30.7% neutral detergent fiber) concentrations. Both diets were formulated with different proportions of the same ingredients. Concentrations of B vitamins were analyzed in feed and duodenal digesta. Apparent ruminal synthesis of each B vitamin was calculated as the duodenal flow minus the intake. The high-forage diet had the highest concentrations of riboflavin, niacin, vitamin B 6 , and folates, whereas the low-forage diet had the highest thiamine concentration. Vitamin B 12 in the diets was under the level of detection. Consequently, despite a reduction in dry matter intake when the cows were fed the high-forage diet, increasing dietary forage concentration increased or tended to increase intakes of riboflavin, niacin, and vitamin B 6 but reduced thiamine and folate intakes. Increasing dietary forage concentration reduced apparent ruminal degradation of thiamine and apparent ruminal synthesis of riboflavin, niacin, and folates and increased ruminal degradation of vitamin B 6 , but had no effect on ruminal synthesis of vitamin B 12 . As a consequence, increasing the forage-to-concentrate ratio had no effect on the amounts of thiamine, riboflavin, and vitamin B 12 reaching the small intestine but decreased the amounts of niacin, vitamin B 6 , and folates available for absorption. Apparent ruminal syntheses of riboflavin, niacin, folates, and vitamin B 12 were correlated positively with the amount of starch digested in the rumen and duodenal flow of microbial N, whereas these correlations were negative for thiamine. Apparent ruminal syntheses of thiamine and vitamin B 6 were negatively correlated with their respective intakes, whereas folate intake was positively correlated with its synthesis in the rumen. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Io hot spots - Infrared photometry of satellite occultations

NASA Technical Reports Server (NTRS)

Goguen, J. D.; Matson, D. L.; Sinton, W. M.; Howell, R. R.; Dyck, H. M.

1988-01-01

Io's active hot spots, which are presently mapped on the basis of IR photometry of this moon's occultation by other Gallilean satellites, are obtained with greatest spatial resolution near the sub-earth point. A model is developed for the occultation lightcurves, and its fitting to the data defines the apparent path of the occulting satellite relative to Io; the mean error in apparent relative position of occulting satellites is of the order of 178 km. A heretofore unknown, 20-km diameter hot spot is noted on Io's leading hemisphere.

Hepatitis B and C virus co-infections in human immunodeficiency virus positive North Indian patients

PubMed Central

Gupta, Swati; Singh, Sarman

2006-01-01

AIM: To determine the prevalence of hepatitis B and C virus infections in human immunodeficiency virus (HIV) -positive patients at a tertiary care hospital in New Delhi, India. METHODS: Serum samples from 451 HIV positive patients were analyzed for HBsAg and HCV antibodies during three years (Jan 2003-Dec 2005). The control group comprised of apparently healthy bone-marrow and renal donors. RESULTS: The study population comprised essentially of heterosexually transmitted HIV infection. The prevalence rate of HBsAg in this population was 5.3% as compared to 1.4% in apparently healthy donors (P < 0.001). Though prevalence of HCV co-infection (2.43%) was lower than HBV in this group of HIV positive patients, the prevalence was significantly higher (P < 0.05) than controls (0.7%). Triple infection of HIV, HBV and HCV was not detected in any patient. CONCLUSION: Our study shows a significantly high prevalence of hepatitis virus infections in HIV infected patients. Hepatitis viruses in HIV may lead to faster progression to liver cirrhosis and a higher risk of antiretroviral therapy induced hepatotoxicity. Therefore, it would be advisable to detect hepatitis virus co-infections in these patients at the earliest. PMID:17106941

False Positives in Exoplanet Detection

NASA Astrophysics Data System (ADS)

Leuquire, Jacob; Kasper, David; Jang-Condell, Hannah; Kar, Aman; Sorber, Rebecca; Suhaimi, Afiq; KELT (Kilodegree Extremely Little Telescope)

2018-06-01

Our team at the University of Wyoming uses a 0.6 m telescope at RBO (Red Buttes Observatory) to help confirm results on potential exoplanet candidates from low resolution, wide field surveys shared by the KELT (Kilodegree Extremely Little Telescope) team. False positives are common in this work. We carry out transit photometry, and this method comes with special types of false positives. The most common false positive seen at the confirmation level is an EB (eclipsing binary). Low resolution images are great in detecting multiple sources for photometric dips in light curves, but they lack the precision to decipher single targets at an accurate level. For example, target star KC18C030621 needed RBO’s photometric precision to determine there was a nearby EB causing exoplanet type light curves. Identifying false positives with our telescope is important work because it helps eliminate the waste of time taken by more expensive telescopes trying to rule out negative candidate stars. It also furthers the identification of other types of photometric events, like eclipsing binaries, so they can be studied on their own.

Oxybuprocaine induces a false-positive response in immunochromatographic SAS Adeno Test.

PubMed

Hoshino, Takeshi; Takanashi, Taiji; Okada, Morio; Uchida, Sunao

2002-04-01

To investigate whether a solution of oxybuprocaine hydrochloride, 0.4%, results in a false-positive response in an immunochromatographic SAS Adeno Test. Experimental study. Physiologic saline and 2% lidocaine. Each chemical (100 microl) was diluted in a transport medium. Five drops (200 microl) of the resultant solution were dispensed into the round sample well of a test device. Fifteen samples were tested in each group. Ten minutes after the start of the test, a colored line in the "specimen" portion of the test membrane was visually read as positive or negative by a masked technician. No positive reaction was observed in the control groups (physiologic saline and lidocaine). A false-positive reaction was observed in six samples (33.3%) in the oxybuprocaine group. The positive rate was significantly higher in the oxybuprocaine group compared with those in control groups (P = 0.0062, Fisher's extract probability test). Oxybuprocaine may induce a false-positive reaction in an immunochromatographic SAS Adeno Test. We recommend the use of lidocaine, instead of oxybuprocaine, for local anesthesia in taking eye swabs from patients with suspected adenovirus infection.

Visual field progression in glaucoma: what is the specificity of the Guided Progression Analysis?

PubMed

Artes, Paul H; O'Leary, Neil; Nicolela, Marcelo T; Chauhan, Balwantray C; Crabb, David P

2014-10-01

To estimate the specificity of the Guided Progression Analysis (GPA) (Carl Zeiss Meditec, Dublin, CA) in individual patients with glaucoma. Observational cohort study. Thirty patients with open-angle glaucoma. In 30 patients with open-angle glaucoma, 1 eye (median mean deviation [MD], -2.5 decibels [dB]; interquartile range, -4.4 to -1.3 dB) was tested 12 times over 3 months (Humphrey Field Analyzer, Carl Zeiss Meditec; SITA Standard, 24-2). "Possible progression" and "likely progression" were determined with the GPA. These analyses were repeated after the order of the tests had been randomly rearranged (1000 unique permutations). Rate of false-positive alerts of "possible progression" and "likely progression" with the GPA. On average, the specificity of the GPA "likely progression" alert was high-for the entire sample, the mean rate of false-positive alerts after 10 follow-up tests was 2.6%. With "possible progression," the specificity was considerably lower (false-positive rate, 18.5%). Most important, the cumulative rate of false-positive alerts varied substantially among patients, from <1% to 80% with "possible progression" and from <0.1% to 20% with "likely progression." Factors associated with false-positive alerts were visual field variability (standard deviation of MD, Spearman's rho = 0.41, P<0.001) and the reliability indices (proportion of false-positive and false-negative responses, fixation losses, rho>0.31, P≤0.10). On average, progression criteria currently used in the GPA have high specificity, but some patients are more likely to show false-positive alerts than others. This is a natural consequence of population-based change criteria and may not matter in clinical trials and studies in which large groups of patients are compared. However, it must be considered when the GPA is used in clinical practice where specificity needs to be controlled for individual patients. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Do positive schizotypal symptoms predict false perceptual experiences in nonclinical populations?

PubMed

Tsakanikos, Elias; Reed, Phil

2005-12-01

We examined whether positive schizotypy (i.e., reports of hallucinatory and delusional-like experiences) in nonclinical participants could predict false perceptual experiences during detection of fast-moving words beyond a possible response bias. The participants (N = 160) were assigned to one of two conditions: they were asked either to make presence/absence judgments (loose criterion) or to read aloud every detected word (strict criterion). Regression analysis showed that high levels of positive schizotypy predicted false alarms in the loose condition and false perceptions of words in the strict condition. The obtained effects were independent of detection accuracy, task order, impulsivity, and social desirability. We discuss the results in the context of information processing biases linked to the positive symptomatology of schizophrenia. Clinical and theoretical implications are also considered.

False Memory in Adults With ADHD: A Comparison Between Subtypes and Normal Controls.

PubMed

Soliman, Abdrabo Moghazy; Elfar, Rania Mohamed

2017-10-01

To examine the performance on the Deese-Roediger-McDermott task of adults divided into ADHD subtypes and compares their performance to that of healthy controls to examine whether adults with ADHD are more susceptible to the production of false memories under experimental conditions. A total of 128 adults with ADHD (50% females), classified into three Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV-TR) subtypes, were compared with 48 controls. The results indicated that the ADHD participants recalled and recognized fewer studied words than the controls, the ADHD groups produced more false memories than the control group, no differences in either the false positives or the false negatives. The ADHD-combined (ADHD-CT) group recognized significantly more critical words than the control, ADHD-predominantly inattentive (ADHD-IA), and ADHD-predominantly hyperactive-impulsive (ADHD-HI) groups. The ADHD groups recalled and recognized more false positives, were more confident in their false responses, and displayed more knowledge corruption than the controls. The ADHD-CT group recalled and recognized more false positives than the other ADHD groups. The adults with ADHD have more false memories than the controls and that false memory formation varied with the ADHD subtypes.

SU-E-J-219: Quantitative Evaluation of Motion Effects On Accuracy of Image-Guided Radiotherapy with Fiducial Markers Using CT Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, I; Oyewale, S; Ahmad, S

2014-06-01

Purpose: To investigate quantitatively patient motion effects on the localization accuracy of image-guided radiation with fiducial markers using axial CT (ACT), helical CT (HCT) and cone-beam CT (CBCT) using modeling and experimental phantom studies. Methods: Markers with different lengths (2.5 mm, 5 mm, 10 mm, and 20 mm) were inserted in a mobile thorax phantom which was imaged using ACT, HCT and CBCT. The phantom moved with sinusoidal motion with amplitudes ranging 0–20 mm and a frequency of 15 cycles-per-minute. Three parameters that include: apparent marker lengths, center position and distance between the centers of the markers were measured inmore » the different CT images of the mobile phantom. A motion mathematical model was derived to predict the variations in the previous three parameters and their dependence on the motion in the different imaging modalities. Results: In CBCT, the measured marker lengths increased linearly with increase in motion amplitude. For example, the apparent length of the 10 mm marker was about 20 mm when phantom moved with amplitude of 5 mm. Although the markers have elongated, the center position and the distance between markers remained at the same position for different motion amplitudes in CBCT. These parameters were not affected by motion frequency and phase in CBCT. In HCT and ACT, the measured marker length, center and distance between markers varied irregularly with motion parameters. The apparent lengths of the markers varied with inverse of the phantom velocity which depends on motion frequency and phase. Similarly the center position and distance between markers varied inversely with phantom speed. Conclusion: Motion may lead to variations in maker length, center position and distance between markers using CT imaging. These effects should be considered in patient setup using image-guided radiation therapy based on fiducial markers matching using 2D-radiographs or volumetric CT imaging.« less

[Rigor mortis -- a definite sign of death?].

PubMed

Heller, A R; Müller, M P; Frank, M D; Dressler, J

2005-04-01

In the past years an ongoing controversial debate exists in Germany, regarding quality of the coroner's inquest and declaration of death by physicians. We report the case of a 90-year old female, who was found after an unknown time following a suicide attempt with benzodiazepine. The examination of the patient showed livores (mortis?) on the left forearm and left lower leg. Moreover, rigor (mortis?) of the left arm was apparent which prevented arm flexion and extension. The hypothermic patient with insufficient respiration was intubated and mechanically ventilated. Chest compressions were not performed, because central pulses were (hardly) palpable and a sinus bradycardia 45/min (AV-block 2 degrees and sole premature ventricular complexes) was present. After placement of an intravenous line (17 G, external jugular vein) the hemodynamic situation was stabilized with intermittent boli of epinephrine and with sodium bicarbonate. With improved circulation livores and rigor disappeared. In the present case a minimal central circulation was noted, which could be stabilized, despite the presence of certain signs of death ( livores and rigor mortis). Considering the finding of an abrogated peripheral perfusion (livores), we postulate a centripetal collapse of glycogen and ATP supply in the patients left arm (rigor), which was restored after resuscitation and reperfusion. Thus, it appears that livores and rigor are not sensitive enough to exclude a vita minima, in particular in hypothermic patients with intoxications. Consequently a careful ABC-check should be performed even in the presence of apparently certain signs of death, to avoid underdiagnosing a vita minima. Additional ECG- monitoring is required to reduce the rate of false positive declarations of death. To what extent basic life support by paramedics should commence when rigor and livores are present until physician DNR order, deserves further discussion.

DCE-MRI-Derived Volume Transfer Constant (Ktrans) and DWI Apparent Diffusion Coefficient as Predictive Markers of Short- and Long-Term Efficacy of Chemoradiotherapy in Patients With Esophageal Cancer.

PubMed

Ye, Zhi-Min; Dai, Shu-Jun; Yan, Feng-Qin; Wang, Lei; Fang, Jun; Fu, Zhen-Fu; Wang, Yue-Zhen

2018-01-01

This study aimed to evaluate both the short- and long-term efficacies of chemoradiotherapy in relation to the treatment of esophageal cancer . This was achieved through the use of dynamic contrast-enhanced magnetic resonance imaging-derived volume transfer constant and diffusion weighted imaging-derived apparent diffusion coefficient . Patients with esophageal cancer were assigned into the sensitive and resistant groups based on respective efficacies in chemoradiotherapy. Dynamic contrast-enhanced magnetic resonance imaging and diffusion weighted imaging were used to measure volume transfer constant and apparent diffusion coefficient, while computed tomography was used to calculate tumor size reduction rate. Pearson correlation analyses were conducted to analyze correlation between volume transfer constant, apparent diffusion coefficient, and the tumor size reduction rate. Receiver operating characteristic curve was constructed to analyze the short-term efficacy of volume transfer constant and apparent diffusion coefficient, while Kaplan-Meier curve was employed for survival rate analysis. Cox proportional hazard model was used for the risk factors for prognosis of patients with esophageal cancer. Our results indicated reduced levels of volume transfer constant, while increased levels were observed in ADC min , ADC mean , and ADC max following chemoradiotherapy. A negative correlation was determined between ADC min , ADC mean , and ADC max , as well as in the tumor size reduction rate prior to chemoradiotherapy, whereas a positive correlation was uncovered postchemoradiotherapy. Volume transfer constant was positively correlated with tumor size reduction rate both before and after chemoradiotherapy. The 5-year survival rate of patients with esophageal cancer having high ADC min , ADC mean , and ADC max and volume transfer constant before chemoradiotherapy was greater than those with respectively lower values. According to the Cox proportional hazard model, ADC mean , clinical stage, degree of differentiation, and tumor stage were all confirmed as being independent risk factors in regard to the prognosis of patients with EC. The findings of this study provide evidence suggesting that volume transfer constant and apparent diffusion coefficient as being tools allowing for the evaluation of both the short- and long-term efficacies of chemoradiotherapy esophageal cancer treatment.

Misdiagnosis of HIV infection during a South African community-based survey: implications for rapid HIV testing

PubMed Central

Kufa, Tendesayi; Kharsany, Ayesha BM; Cawood, Cherie; Khanyile, David; Lewis, Lara; Grobler, Anneke; Chipeta, Zawadi; Bere, Alfred; Glenshaw, Mary; Puren, Adrian

2017-01-01

Abstract Introduction: We describe the overall accuracy and performance of a serial rapid HIV testing algorithm used in community-based HIV testing in the context of a population-based household survey conducted in two sub-districts of uMgungundlovu district, KwaZulu-Natal, South Africa, against reference fourth-generation HIV-1/2 antibody and p24 antigen combination immunoassays. We discuss implications of the findings on rapid HIV testing programmes. Methods: Cross-sectional design: Following enrolment into the survey, questionnaires were administered to eligible and consenting participants in order to obtain demographic and HIV-related data. Peripheral blood samples were collected for HIV-related testing. Participants were offered community-based HIV testing in the home by trained field workers using a serial algorithm with two rapid diagnostic tests (RDTs) in series. In the laboratory, reference HIV testing was conducted using two fourth-generation immunoassays with all positives in the confirmatory test considered true positives. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value and false-positive and false-negative rates were determined. Results: Of 10,236 individuals enrolled in the survey, 3740 were tested in the home (median age 24 years (interquartile range 19–31 years), 42.1% males and HIV positivity on RDT algorithm 8.0%). From those tested, 3729 (99.7%) had a definitive RDT result as well as a laboratory immunoassay result. The overall accuracy of the RDT when compared to the fourth-generation immunoassays was 98.8% (95% confidence interval (CI) 98.5–99.2). The sensitivity, specificity, positive predictive value and negative predictive value were 91.1% (95% CI 87.5–93.7), 99.9% (95% CI 99.8–100), 99.3% (95% CI 97.4–99.8) and 99.1% (95% CI 98.8–99.4) respectively. The false-positive and false-negative rates were 0.06% (95% CI 0.01–0.24) and 8.9% (95% CI 6.3–12.53). Compared to true positives, false negatives were more likely to be recently infected on limited antigen avidity assay and to report antiretroviral therapy (ART) use. Conclusions: The overall accuracy of the RDT algorithm was high. However, there were few false positives, and the sensitivity was lower than expected with high false negatives, despite implementation of quality assurance measures. False negatives were associated with recent (early) infection and ART exposure. The RDT algorithm was able to correctly identify the majority of HIV infections in community-based HIV testing. Messaging on the potential for false positives and false negatives should be included in these programmes. PMID:28872274

Affective valence influences participant's susceptibility to false memories and illusory recollection.

PubMed

Dehon, Hedwige; Larøi, Frank; Van der Linden, Martial

2010-10-01

This study examined the influence of emotional valence on the production of DRM false memories (Roediger & McDermott, 1995). Participants were presented with neutral, positive, or negative DRM lists for a later recognition (Experiment 1) or recall (Experiment 2) test. In both experiments, confidence and recollective experience (i.e., "Remember-Know" judgments; Tulving, 1985) were also assessed. Results consistently showed that, compared with neutral lists, affective lists induced more false recognition and recall of nonpresented critical lures. Moreover, although confidence ratings did not differ between the false remembering from the different kinds of lists, "Remember" responses were more often associated with negative than positive and neutral false remembering of the critical lures. In contrast, positive false remembering of the critical lures was more often associated with "Know" responses. These results are discussed in light of the Paradoxical Negative Emotion (PNE) hypothesis (Porter, Taylor, & ten Bricke, 2008). (PsycINFO Database Record (c) 2010 APA, all rights reserved).

Hair Follicle Bulb as a Biodosimeter for Low-Level VX Vapor Exposure: Initial Studies Validating the Presence of Potential Protein Biomarkers of Exposure in the Sprague-Dawley Rat Whisker Follicle

DTIC Science & Technology

2006-10-01

lead to false positive segmental hair analysis results.13 Due to the increased risk of false positives associated with segmental hair analysis ...to 200 mg of hair (to allow confirmation testing). 7 The segments are typically washed to remove external contaminants and the chemicals in the hair ...further confirmation. The method overcomes the false positives associated with traditional segmental hair analysis such. By measuring the

Early Disseminated Lyme Disease Causing False-Positive Serology for Primary Epstein-Barr Virus Infection: Report of 2 Cases.

PubMed

Pavletic, Adriana J; Marques, Adriana R

2017-07-15

False-positive serology for Lyme disease was reported in patients with acute infectious mononucleosis. Here we describe 2 patients with early disseminated Lyme disease who were misdiagnosed with infectious mononucleosis based on false-positive tests for primary Epstein-Barr virus infection. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Statistics provide guidance for indigenous organic carbon detection on Mars missions.

PubMed

Sephton, Mark A; Carter, Jonathan N

2014-08-01

Data from the Viking and Mars Science Laboratory missions indicate the presence of organic compounds that are not definitively martian in origin. Both contamination and confounding mineralogies have been suggested as alternatives to indigenous organic carbon. Intuitive thought suggests that we are repeatedly obtaining data that confirms the same level of uncertainty. Bayesian statistics may suggest otherwise. If an organic detection method has a true positive to false positive ratio greater than one, then repeated organic matter detection progressively increases the probability of indigeneity. Bayesian statistics also reveal that methods with higher ratios of true positives to false positives give higher overall probabilities and that detection of organic matter in a sample with a higher prior probability of indigenous organic carbon produces greater confidence. Bayesian statistics, therefore, provide guidance for the planning and operation of organic carbon detection activities on Mars. Suggestions for future organic carbon detection missions and instruments are as follows: (i) On Earth, instruments should be tested with analog samples of known organic content to determine their true positive to false positive ratios. (ii) On the mission, for an instrument with a true positive to false positive ratio above one, it should be recognized that each positive detection of organic carbon will result in a progressive increase in the probability of indigenous organic carbon being present; repeated measurements, therefore, can overcome some of the deficiencies of a less-than-definitive test. (iii) For a fixed number of analyses, the highest true positive to false positive ratio method or instrument will provide the greatest probability that indigenous organic carbon is present. (iv) On Mars, analyses should concentrate on samples with highest prior probability of indigenous organic carbon; intuitive desires to contrast samples of high prior probability and low prior probability of indigenous organic carbon should be resisted.

Positive events protect children from causal false memories for scripted events.

PubMed

Melinder, Annika; Toffalini, Enrico; Geccherle, Eleonora; Cornoldi, Cesare

2017-11-01

Adults produce fewer inferential false memories for scripted events when their conclusions are emotionally charged than when they are neutral, but it is not clear whether the same effect is also found in children. In the present study, we examined this issue in a sample of 132 children aged 6-12 years (mean 9 years, 3 months). Participants encoded photographs depicting six script-like events that had a positively, negatively, or a neutral valenced ending. Subsequently, true and false recognition memory of photographs related to the observed scripts was tested as a function of emotionality. Causal errors-a type of false memory thought to stem from inferential processes-were found to be affected by valence: children made fewer causal errors for positive than for neutral or negative events. Hypotheses are proposed on why adults were found protected against inferential false memories not only by positive (as for children) but also by negative endings when administered similar versions of the same paradigm.

[Grain Size Distribution Characteristics of Suspended Particulate Matter as Influenced by the Apparent Pollution in the Eutrophic Urban Landscape Water Body].

PubMed

Gong, Dan-yan; Pan, Yang; Huang, Yong; Bao, Wei; Li, Qian-qian

2016-03-15

Grain size distribution characteristics of suspended particulate matter (SPM) reflects the apparent polluted condition of the urban landscape water. In order to explore the internal relationship between the eutrophication of urban landscape water's apparent pollution and grain size distribution of SPM, and its influencing factors, this paper selected five representative sampling sites in Feng Jin River which is a typical eutrophication river in Suzhou City, measured the grain size distribution of SPM, sensation pollution index (SPI) and water quality index, and analyzed their correlation. The results showed that: The rich nutrient water possessed a similar characteristics in grain size distribution. The grain size distribution of SPM in water was multimodal, and the the peak position was roughly the same; the grain size distribution of SPM was composed by multiple components. It could be roughly divided into six parts with the particle size range of every group being < 1.5 µm, 1.5-8 µm, 8-35 µm, 35-186 µm, 186-516 µm, > 516 µm. The component III was superior (with an average volume fraction of 38.3%-43.2%), and its volume fraction had a significant positive relation with the SPI value and the Chl-a content. The increase of component III volume fraction was the reflection of particle size's result of increasing SPI value. The increase of component III volume fraction was mainly derived from the increasing algal content. The volume fraction of group IV + group VI + group V was significantly higher under the condition of exogenous enter. When there was no exogenous component, the volume fraction of group IV + group VI + group V had a significant negative correlation with SPI value; when there were exogenous components, the volume fraction of group IV + group VI + group V had a weak positive correlation with SPI value, but the correlation did not reach a significant level. Environmental factors (Fv/Fm and DO) and exogenous factors had an influence by functioning on the algal content which signified the polluted material, and then affected the volume fraction of particle size's components and the quality of apparent water. Hydrodynamic conditions mainly had a certain influence on the median particle size, and had no effect on the apparent polluted condition of water.

False-positive rate determination of protein target discovery using a covalent modification- and mass spectrometry-based proteomics platform.

PubMed

Strickland, Erin C; Geer, M Ariel; Hong, Jiyong; Fitzgerald, Michael C

2014-01-01

Detection and quantitation of protein-ligand binding interactions is important in many areas of biological research. Stability of proteins from rates of oxidation (SPROX) is an energetics-based technique for identifying the proteins targets of ligands in complex biological mixtures. Knowing the false-positive rate of protein target discovery in proteome-wide SPROX experiments is important for the correct interpretation of results. Reported here are the results of a control SPROX experiment in which chemical denaturation data is obtained on the proteins in two samples that originated from the same yeast lysate, as would be done in a typical SPROX experiment except that one sample would be spiked with the test ligand. False-positive rates of 1.2-2.2% and <0.8% are calculated for SPROX experiments using Q-TOF and Orbitrap mass spectrometer systems, respectively. Our results indicate that the false-positive rate is largely determined by random errors associated with the mass spectral analysis of the isobaric mass tag (e.g., iTRAQ®) reporter ions used for peptide quantitation. Our results also suggest that technical replicates can be used to effectively eliminate such false positives that result from this random error, as is demonstrated in a SPROX experiment to identify yeast protein targets of the drug, manassantin A. The impact of ion purity in the tandem mass spectral analyses and of background oxidation on the false-positive rate of protein target discovery using SPROX is also discussed.

Minimizing false positive error with multiple performance validity tests: response to Bilder, Sugar, and Hellemann (2014 this issue).

PubMed

Larrabee, Glenn J

2014-01-01

Bilder, Sugar, and Hellemann (2014 this issue) contend that empirical support is lacking for use of multiple performance validity tests (PVTs) in evaluation of the individual case, differing from the conclusions of Davis and Millis (2014), and Larrabee (2014), who found no substantial increase in false positive rates using a criterion of failure of ≥ 2 PVTs and/or Symptom Validity Tests (SVTs) out of multiple tests administered. Reconsideration of data presented in Larrabee (2014) supports a criterion of ≥ 2 out of up to 7 PVTs/SVTs, as keeping false positive rates close to and in most cases below 10% in cases with bona fide neurologic, psychiatric, and developmental disorders. Strategies to minimize risk of false positive error are discussed, including (1) adjusting individual PVT cutoffs or criterion for number of PVTs failed, for examinees who have clinical histories placing them at risk for false positive identification (e.g., severe TBI, schizophrenia), (2) using the history of the individual case to rule out conditions known to result in false positive errors, (3) using normal performance in domains mimicked by PVTs to show that sufficient native ability exists for valid performance on the PVT(s) that have been failed, and (4) recognizing that as the number of PVTs/SVTs failed increases, the likelihood of valid clinical presentation decreases, with a corresponding increase in the likelihood of invalid test performance and symptom report.

An Evaluation of Unit and ½ Mass Correction Approaches as a ...

EPA Pesticide Factsheets

Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive on 66Zn. Currently, US EPA Method 200.8 does not address these as sources of false positives. Additionally, these M+2 false positives are typically enhanced if collision cell technology is utilized to reduce polyatomic interferences associated with ICP-MS detection. A preliminary evaluation indicates that instrumental tuning conditions can impact the observed M+2/M+1 ratio and in turn the false positives generated on Zn, As and Se. Both unit and ½ mass approaches will be evaluated to correct for these false positives relative to the benchmark concentrations estimates from a triple quadrupole ICP-MS using standard solutions. The impact of matrix on these M+2 corrections will be evaluated over multiple analysis days with a focus on evaluating internal standards that mirror the matrix induced shifts in the M+2 ion transmission. The goal of this evaluation is to move away from fixed M+2 corrective approaches and move towards sample specific approaches that mimic the sample matrix induced variability while attempting to address intra-day variability of the M+2 correction factors through the use of internal standards. Oral Presentation via webinar for EPA Laboratory Technical Informati

Analysis of positional isotope exchange in ATP by cleavage of the beta P-O gamma P bond. Demonstration of negligible positional isotope exchange by myosin.

PubMed

Dale, M P; Hackney, D D

1987-12-15

A method for analysis of positional isotope exchange (PIX) during ATP in equilibrium with HOH oxygen exchange is presented that uses a two-step degradation of ATP resulting in cleavage of the beta P-O gamma P bond. This cleavage yields Pi derived from the gamma-phosphoryl of ATP that contains all four of the gamma oxygens. Both PIX between the beta,gamma-bridge and beta-nonbridge positions and washout of the gamma-nonbridge oxygens can be simultaneously followed by using ATP labeled with 17O at the beta-nonbridge positions and 18O at the beta,gamma-bridge and gamma-nonbridge positions. Application of this method to ATP in equilibrium with HOH exchange during single turnovers of myosin indicates that the bulk of the ATP undergoes rapid washout of gamma-nonbridge oxygens in the virtual absence of PIX. At 25 degrees C with subfragment 1 the scrambling rate is at the limit of detectability of approximately 0.001 s-1, which is 50-fold slower than the steady-state rate. This corresponds to a probability of scrambling for the beta-oxygens of bound ADP of 1 in 10,000 for each cycle of reversible hydrolysis of bound ATP. A fraction of the ATP, however, does not undergo rapid washout. With myosin and stoichiometric ATP at 0 degrees C, this fraction corresponds to 10% of the ATP remaining at 36 s, or 2% of the initial ATP, and an equivalent level of ATP is found that does not bind irreversibly to myosin in a cold chase experiment. A significant level of apparent PIX is observed with subfragment 1 in the fraction that resists washout, and this apparent PIX is shown to be due to contaminant adenylate kinase activity. This apparent PIX due to adenylate kinase provides a possible explanation for the PIX observed by Geeves et al. [Geeves, M. A., Webb, M. R., Midelfort, C. F., & Trentham, D. R. (1980) Biochemistry 19, 4748-4754] with subfragment 1.

Unrecognized Subclinical Infection with Tickborne Encephalitis Virus, Japan

PubMed Central

Yoshii, Kentaro; Kojima, Reiji

2017-01-01

During early 2017, we conducted a seroepidemiologic investigation for tickborne encephalitis virus among 291 Japan Self-Defense Forces members in Hokkaido. Two (0.7%) tested positive. Neither had clinically apparent symptoms after removing ticks. PMID:28930025

Localization of Virtual Objects in the Near Visual Field (Operator Interaction with Simple Virtual Objects)

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.; Menges, Brian M.

1998-01-01

Errors in the localization of nearby virtual objects presented via see-through, helmet mounted displays are examined as a function of viewing conditions and scene content in four experiments using a total of 38 subjects. Monocular, biocular or stereoscopic presentation of the virtual objects, accommodation (required focus), subjects' age, and the position of physical surfaces are examined. Nearby physical surfaces are found to introduce localization errors that differ depending upon the other experimental factors. These errors apparently arise from the occlusion of the physical background by the optically superimposed virtual objects. But they are modified by subjects' accommodative competence and specific viewing conditions. The apparent physical size and transparency of the virtual objects and physical surfaces respectively are influenced by their relative position when superimposed. The design implications of the findings are discussed in a concluding section.

Calculating the spontaneous magnetization and defining the Curie temperature using a positive-feedback model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, R. G., E-mail: rgh@doe.carleton.ca

2014-01-21

A positive-feedback mean-field modification of the classical Brillouin magnetization theory provides an explanation of the apparent persistence of the spontaneous magnetization beyond the conventional Curie temperature—the little understood “tail” phenomenon that occurs in many ferromagnetic materials. The classical theory is unable to resolve this apparent anomaly. The modified theory incorporates the temperature-dependent quantum-scale hysteretic and mesoscopic domain-scale anhysteretic magnetization processes and includes the effects of demagnetizing and exchange fields. It is found that the thermal behavior of the reversible and irreversible segments of the hysteresis loops, as predicted by the theory, is a key to the presence or absence ofmore » the “tails.” The theory, which permits arbitrary values of the quantum spin number J, generally provides a quantitative agreement with the thermal variations of both the spontaneous magnetization and the shape of the hysteresis loop.« less

Quality control in the diagnosis of Trichuris trichiura and Ascaris lumbricoides using the Kato-Katz technique: experience from three randomised controlled trials.

PubMed

Speich, Benjamin; Ali, Said M; Ame, Shaali M; Albonico, Marco; Utzinger, Jürg; Keiser, Jennifer

2015-02-05

An accurate diagnosis of soil-transmitted helminthiasis is important for individual patient management, for drug efficacy evaluation and for monitoring control programmes. The Kato-Katz technique is the most widely used method detecting soil-transmitted helminth eggs in faecal samples. However, detailed analyses of quality control, including false-positive and faecal egg count (FEC) estimates, have received little attention. Over a 3-year period, within the frame of a series of randomised controlled trials conducted in Pemba, United Republic of Tanzania, 10% of randomly selected Kato-Katz thick smears were re-read for Trichuris trichiura and Ascaris lumbricoides eggs. In case of discordant result (i.e. positive versus negative) the slides were re-examined a third time. A result was assumed to be false-positive or false-negative if the result from the initial reading did not agree with the quality control as well as the third reading. We also evaluated the general agreement in FECs between the first and second reading, according to internal and World Health Organization (WHO) guidelines. From the 1,445 Kato-Katz thick smears subjected to quality control, 1,181 (81.7%) were positive for T. trichiura and 290 (20.1%) were positive for A. lumbricoides. During quality control, very low rates of false-positive results were observed; 0.35% (n = 5) for T. trichiura and 0.28% (n = 4) for A. lumbricoides. False-negative readings of Kato-Katz thick smears were obtained in 28 (1.94%) and 6 (0.42%) instances for T. trichiura and A. lumbricoides, respectively. A high frequency of discordant results in FECs was observed (i.e. 10.0-23.9% for T. trichiura, and 9.0-11.4% for A. lumbricoides). Our analyses show that the rate of false-positive diagnoses of soil-transmitted helminths is low. As the probability of false-positive results increases after examination of multiple stool samples from a single individual, the potential influence of false-positive results on epidemiological studies and anthelminthic drug efficacy studies should be determined. Existing WHO guidelines for quality control might be overambitious and might have to be revised, specifically with regard to handling disagreements in FECs.

Extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax: experience at a community based level I trauma center.

PubMed

Nandipati, Kalyana C; Allamaneni, Shyam; Kakarla, Ravindra; Wong, Alfredo; Richards, Neil; Satterfield, James; Turner, James W; Sung, Kae-Jae

2011-05-01

Early identification of pneumothorax is crucial to reduce the mortality in critically injured patients. The objective of our study is to investigate the utility of surgeon performed extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax. We prospectively analysed 204 trauma patients in our level I trauma center over a period of 12 (06/2007-05/2008) months in whom EFAST was performed. The patients' demographics, type of injury, clinical examination findings (decreased air entry), CXR, EFAST and CT scan findings were entered into the data base. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. Of 204 patients (mean age--43.01+/-19.5 years, sex--male 152, female 52) 21 (10.3%) patients had pneumothorax. Of 21 patients who had pneumothorax 12 were due to blunt trauma and 9 were due to penetrating trauma. The diagnosis of pneumothorax in 204 patients demonstrated the following: clinical examination was positive in 17 patients (true positive in 13/21, 62%; 4 were false positive and 8 were false negative), CXR was positive in 16 (true positive in 15/19, 79%; 1 false positive, 4 missed and 2 CXR not performed before chest tube) patients and EFAST was positive in 21 patients (20 were true positive [95.2%], 1 false positive and 1 false negative). In diagnosing pneumothorax EFAST has significantly higher sensitivity compared to the CXR (P=0.02). Surgeon performed trauma room extended FAST is simple and has higher sensitivity compared to the chest X-ray and clinical examination in detecting pneumothorax. Published by Elsevier Ltd.

When good news is bad news: psychological impact of false positive diagnosis of HIV.

PubMed

Bhattacharya, Rahul; Barton, Simon; Catalan, Jose

2008-05-01

HIV testing is known to be stressful, however the impact of false positive HIV results on individuals is not well documented. This is a series of four case who developed psychological difficulties and psychiatric morbidities after being informed they had been misdiagnosed with HIV-positive status. We look into documented cases of misdiagnosis and potential risks of misdiagnosis. The case series highlights the implications a false diagnosis HIV-positive status can have, even when the diagnosis is rectified. Impact of misdiagnosis of HIV can lead to psychosocial difficulties and psychiatric morbidity, have public health and epidemiological implications and can lead to medico-legal conflict. This further reiterates the importance of HIV testing carried out ethically and sensitively, and in line with guidelines, respecting confidentiality and consent, and offering counselling pre-test and post-test, being mindful of the reality of erroneous and false positive HIV test results. The implications of misdiagnosis are for the individual, their partners and social contacts, as well as for the community.

False-positive iodine-131 whole-body scan findings in patients with differentiated thyroid carcinoma: report of 11 cases and review of the literature.

PubMed

Buton, Leckzinscka; Morel, Olivier; Gault, Patricia; Illouz, Frédéric; Rodien, Patrice; Rohmer, Vincent

2013-07-01

Iodine-131 (I-131) whole-body scan (WBS) plays an important role in the management of patients with differentiated thyroid carcinoma (DTC), to detect normal thyroid remnants and recurrent or metastatic disease. A focus of I-131 accumulation outside the thyroid bed and the areas of physiological uptake is strongly suggestive of a distant functioning metastasis. However, many false-positive I-131 WBS findings have been reported in the literature. We describe a series of 11 personal cases of patients with DTC, collected from 1992 to 2011, in whom diagnostic or post-treatment WBS showed false-positive retention of I-131 in various locations. False-positive accumulations of I-131 on WBS may be classified according to the underlying pathophysiological mechanisms: external and internal contaminations by body secretions, ectopic normal thyroid and gastric tissues, inflammatory and infectious diseases, benign and malignant tumors, cysts and effusions of serous cavities, thymic uptake, and other non classified causes. Clinicians must be aware of possible false-positive findings to avoid misinterpretations of the I-131 WBS, which could lead to inappropriate treatments. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Comparing diagnostic tests on benefit-risk.

PubMed

Pennello, Gene; Pantoja-Galicia, Norberto; Evans, Scott

2016-01-01

Comparing diagnostic tests on accuracy alone can be inconclusive. For example, a test may have better sensitivity than another test yet worse specificity. Comparing tests on benefit risk may be more conclusive because clinical consequences of diagnostic error are considered. For benefit-risk evaluation, we propose diagnostic yield, the expected distribution of subjects with true positive, false positive, true negative, and false negative test results in a hypothetical population. We construct a table of diagnostic yield that includes the number of false positive subjects experiencing adverse consequences from unnecessary work-up. We then develop a decision theory for evaluating tests. The theory provides additional interpretation to quantities in the diagnostic yield table. It also indicates that the expected utility of a test relative to a perfect test is a weighted accuracy measure, the average of sensitivity and specificity weighted for prevalence and relative importance of false positive and false negative testing errors, also interpretable as the cost-benefit ratio of treating non-diseased and diseased subjects. We propose plots of diagnostic yield, weighted accuracy, and relative net benefit of tests as functions of prevalence or cost-benefit ratio. Concepts are illustrated with hypothetical screening tests for colorectal cancer with test positive subjects being referred to colonoscopy.

Gas insufflation of minimal preparation CT of the colon reduces false-positives

PubMed Central

Slater, A; North, M; Hart, M; Ferrett, C

2012-01-01

Objectives Minimal preparation CT of the colon (MPCT colon) is used for investigation of suspected colorectal cancer in frail and/or elderly patients who would be expected to tolerate laxative bowel preparation poorly. Although it has good sensitivity for colorectal cancer it has a poor specificity. We wished to investigate whether distension of the colon with carbon dioxide alone would reduce the number of false-positives, but without making the test arduous or excessively uncomfortable. Methods 134 patients were recruited and underwent MPCT colon with gas insufflation and antispasmodics. Results were compared with a cohort of 134 patients undergoing standard protocol MPCT colon. The numbers of false-positives were compared, as was reader confidence. All trial patients were given a questionnaire documenting their experience. Results The number of false-positives was 15% in the control group and 5% in the trial group; this difference was statistically significant, (p=0.01). Reader confidence was increased in the trial group. Patient tolerance was good, with 95% saying they would have the test again. Conclusion Use of gas insufflation and antispasmodics reduces the false-positives from 15% to 5% without adversely affecting patient tolerance. PMID:21224295

False memories, but not false beliefs, affect implicit attitudes for food preferences.

PubMed

Howe, David; Anderson, Rachel J; Dewhurst, Stephen A

2017-09-01

Previous studies have found that false memories and false beliefs of childhood experiences can have attitudinal consequences. Previous studies have, however, focused exclusively on explicit attitude measures without exploring whether implicit attitudes are similarly affected. Using a false feedback/imagination inflation paradigm, false memories and beliefs of enjoying a certain food as a child were elicited in participants, and their effects were assessed using both explicit attitude measures (self-report questionnaires) and implicit measures (a Single-Target Implicit Association Test). Positive changes in explicit attitudes were observed both in participants with false memories and participants with false beliefs. In contrast, only participants with false memories exhibited more positive implicit attitudes. The findings are discussed in terms of theories of explicit and implicit attitudes. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of potential false positives via orbitrap-based untargeted lipidomics from rat tissues.

PubMed

Xu, Lina; Wang, Xueying; Jiao, Yupei; Liu, Xiaohui

2018-02-01

Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/MS acquisition is commonly used in order to acquire sufficient information for confident lipid assignment. However, although lipids are identified based on MS/MS confirmation, a number of false positives are still observed. Here, we discuss several causes of introducing lipid false identifications in untargeted analysis. Phosphotidylcholines and cholesteryl esters generate in-source fragmentation to produce dimethylated phosphotidylethanolamine and free cholesterol. Dimerization of fatty acid results in false identification of fatty acid ester of hydroxyl fatty acid. Realizing these false positives is able to improve confidence of results acquired from untargeted analysis. Besides, thresholds are established for lipids identified using LipidSearch v4.1.16 software to reduce unreliable results. Copyright © 2017 Elsevier B.V. All rights reserved.

False-positive psychology: undisclosed flexibility in data collection and analysis allows presenting anything as significant.

PubMed

Simmons, Joseph P; Nelson, Leif D; Simonsohn, Uri

2011-11-01

In this article, we accomplish two things. First, we show that despite empirical psychologists' nominal endorsement of a low rate of false-positive findings (≤ .05), flexibility in data collection, analysis, and reporting dramatically increases actual false-positive rates. In many cases, a researcher is more likely to falsely find evidence that an effect exists than to correctly find evidence that it does not. We present computer simulations and a pair of actual experiments that demonstrate how unacceptably easy it is to accumulate (and report) statistically significant evidence for a false hypothesis. Second, we suggest a simple, low-cost, and straightforwardly effective disclosure-based solution to this problem. The solution involves six concrete requirements for authors and four guidelines for reviewers, all of which impose a minimal burden on the publication process.

Determination of activity coefficient of lanthanum chloride in molten LiCl-KCl eutectic salt as a function of cesium chloride and lanthanum chloride concentrations using electromotive force measurements

NASA Astrophysics Data System (ADS)

Bagri, Prashant; Simpson, Michael F.

2016-12-01

The thermodynamic behavior of lanthanides in molten salt systems is of significant scientific interest for the spent fuel reprocessing of Generation IV reactors. In this study, the apparent standard reduction potential (apparent potential) and activity coefficient of LaCl3 were determined in a molten salt solution of eutectic LiCl-KCl as a function of concentration of LaCl3. The effect of adding up to 1.40 mol % CsCl was also investigated. These properties were determined by measuring the open circuit potential of the La-La(III) redox couple in a high temperature molten salt electrochemical cell. Both the apparent potential and activity coefficient exhibited a strong dependence on concentration. A low concentration (0.69 mol %) of CsCl had no significant effect on the measured properties, while a higher concentration (1.40 mol %) of CsCl caused an increase (become more positive) in the apparent potential and activity coefficient at the higher range of LaCl3 concentrations.

[A novel method for extracting leaf-level solar-induced fluorescence of typical crops under Cu stress].

PubMed

Qu, Ying; Liu, Su-hong; Li, Xiao-wen

2012-05-01

The leaf-level solar-induced fluorescence changes when the typical crops are under Cu stress, which can be considered as a sensitive indicator to estimate the stress level. In the present study, wheat (Triticum aestivum L.), pea (Pisum sativum L.) and Chinese cabbage (Brassica campestris L.) were selected and cultured with copper solutions or copper polluted soil with different Cu stress. The apparent reflectance of leaves was measured by an ASD Fieldspec spectrometer and an integrating sphere. As the apparent reflectance was seldom affected by the fluorescence emission at 580-650 and 800-1000 nm, so the apparent solar-induced fluorescence can be separated from the apparent reflectance based on PROSPECT model. The re-absorption effect of chlorophyll was corrected by three methods, called GM (Gitelson et al.'s model), AM (Agati et al.'s model) and LM (Lagorio et al.'s model). After the re-absorption correction, the solar-induced fluorescence under different Cu stress was obtained, and a positive relationship was found between the height of far RED fluorescence (FRF) and the copper contents in leaves.

Risk of Breast Cancer in Women with False-Positive Results according to Mammographic Features.

PubMed

Castells, Xavier; Torá-Rocamora, Isabel; Posso, Margarita; Román, Marta; Vernet-Tomas, Maria; Rodríguez-Arana, Ana; Domingo, Laia; Vidal, Carmen; Baré, Marisa; Ferrer, Joana; Quintana, María Jesús; Sánchez, Mar; Natal, Carmen; Espinàs, Josep A; Saladié, Francina; Sala, María

2016-08-01

Purpose To assess the risk of breast cancer in women with false-positive screening results according to radiologic classification of mammographic features. Materials and Methods Review board approval was obtained, with waiver of informed consent. This retrospective cohort study included 521 200 women aged 50-69 years who underwent screening as part of the Spanish Breast Cancer Screening Program between 1994 and 2010 and who were observed until December 2012. Cox proportional hazards regression analysis was used to estimate the age-adjusted hazard ratio (HR) of breast cancer and the 95% confidence interval (CI) in women with false-positive mammograms as compared with women with negative mammograms. Separate models were adjusted for screen-detected and interval cancers and for screen-film and digital mammography. Time without a breast cancer diagnosis was plotted by using Kaplan-Meier curves. Results When compared with women with negative mammograms, the age-adjusted HR of cancer in women with false-positive results was 1.84 (95% CI: 1.73, 1.95; P < .001). The risk was higher in women who had calcifications, whether they were (HR, 2.73; 95% CI: 2.28, 3.28; P < .001) or were not (HR, 2.24; 95% CI: 2.02, 2.48; P < .001) associated with masses. Women in whom mammographic features showed changes in subsequent false-positive results were those who had the highest risk (HR, 9.13; 95% CI: 8.28, 10.07; P < .001). Conclusion Women with false-positive results had an increased risk of breast cancer, particularly women who had calcifications at mammography. Women who had more than one examination with false-positive findings and in whom the mammographic features changed over time had a highly increased risk of breast cancer. Previous mammographic features might yield useful information for further risk-prediction models and personalized follow-up screening protocols. (©) RSNA, 2016 Online supplemental material is available for this article.

Effects of low-carbohydrate, high-fat diets on apparent digestibility of minerals and trace elements in rats.

PubMed

Frommelt, Lena; Bielohuby, Maximilian; Stoehr, Barbara J M; Menhofer, Dominik; Bidlingmaier, Martin; Kienzle, Ellen

2014-01-01

Ketogenic low-carbohydrate, high-fat (LCHF) diets reduce growth and bone mineral density in children with epilepsy and in rats. Part of this effect might be due to a reduced availability of calcium in high-fat diets. The aim of this study was to determine mineral digestibility by total collection method in LCHF diets compared with a chow diet and a standard high-fat diet (HFD, high in fat and carbohydrates). Twelve-wk-old male Wistar rats were pair-fed isoenergetic amounts of either six different LCHF diets based on tallow and casein (crude fat 75%-50%, crude protein 10%-35%), with chow or with a HFD diet. Mineral-to-energy ratio was matched in all diets. Circulating parathyroid hormone was measured by immunoassay. The apparent digestibility of calcium was reduced in all HFDs (high-fat diets, LCHF diets and the HFD diet) by at least 30% compared with the chow diet (P < 0.001). Fecal calcium excretion correlated positively with fecal fat excretion, presumably because of formation of calcium soaps. Apparent digestibility of phosphorous was higher in all HFDs. This resulted in a decrease of the ratio of apparently digested calcium to apparently digested phosphorous in all HFDs below a ratio of 1:1. Plasma parathyroid hormone was not affected by any diet. The alteration of apparent calcium and phosphorus digestibility may affect the impact of HFDs on bone metabolism. Copyright © 2014 Elsevier Inc. All rights reserved.

Automatic lung nodule graph cuts segmentation with deep learning false positive reduction

NASA Astrophysics Data System (ADS)

Sun, Wenqing; Huang, Xia; Tseng, Tzu-Liang Bill; Qian, Wei

2017-03-01

To automatic detect lung nodules from CT images, we designed a two stage computer aided detection (CAD) system. The first stage is graph cuts segmentation to identify and segment the nodule candidates, and the second stage is convolutional neural network for false positive reduction. The dataset contains 595 CT cases randomly selected from Lung Image Database Consortium and Image Database Resource Initiative (LIDC/IDRI) and the 305 pulmonary nodules achieved diagnosis consensus by all four experienced radiologists were our detection targets. Consider each slice as an individual sample, 2844 nodules were included in our database. The graph cuts segmentation was conducted in a two-dimension manner, 2733 lung nodule ROIs are successfully identified and segmented. With a false positive reduction by a seven-layer convolutional neural network, 2535 nodules remain detected while the false positive dropped to 31.6%. The average F-measure of segmented lung nodule tissue is 0.8501.

Verification of false-positive blood culture results generated by the BACTEC 9000 series by eubacterial 16S rDNA and panfungal 18S rDNA directed polymerase chain reaction (PCR).

PubMed

Daxboeck, Florian; Dornbusch, Hans Jürgen; Krause, Robert; Assadian, Ojan; Wenisch, Christoph

2004-01-01

A small but significant proportion of blood cultures processed by the BACTEC 9000 series systems is signaled positive, while subsequent Gram's stain and culture on solid media yield no pathogens. In this study, 15 "false-positive" vials (7 aerobes, 8 anaerobes) from 15 patients were investigated for the presence of bacteria and fungi by eubacterial 16S rDNA and panfungal 18S rDNA amplification, respectively. All samples turned out negative by both methods. Most patients (7) had neutropenia, which does not support the theory that high leukocyte counts enhance the generation of false-positive results. In conclusion, the results of this study indicate that false-negative results generated by the BACTEC 9000 series are inherent to the automated detection and not due to the growth of fastidious organisms.

False positives in psychiatric diagnosis: implications for human freedom.

PubMed

Wakefield, Jerome C

2010-02-01

Current symptom-based DSM and ICD diagnostic criteria for mental disorders are prone to yielding false positives because they ignore the context of symptoms. This is often seen as a benign flaw because problems of living and emotional suffering, even if not true disorders, may benefit from support and treatment. However, diagnosis of a disorder in our society has many ramifications not only for treatment choice but for broader social reactions to the diagnosed individual. In particular, mental disorders impose a sick role on individuals and place a burden upon them to change; thus, disorders decrease the level of respect and acceptance generally accorded to those with even annoying normal variations in traits and features. Thus, minimizing false positives is important to a pluralistic society. The harmful dysfunction analysis of disorder is used to diagnose the sources of likely false positives, and propose potential remedies to the current weaknesses in the validity of diagnostic criteria.

False positive malaria rapid diagnostic test in returning traveler with typhoid fever.

PubMed

Meatherall, Bonnie; Preston, Keith; Pillai, Dylan R

2014-07-09

Rapid diagnostic tests play a pivotal role in the early diagnosis of malaria where microscopy or polymerase chain reaction are not immediately available. We report the case of a 39 year old traveler to Canada who presented with fever, headache, and abdominal pain after visiting friends and relatives in India. While in India, the individual was not ill and had no signs or symptoms of malaria. Laboratory testing upon his return to Canada identified a false positive malaria rapid diagnostic (BinaxNOW® malaria) result for P. falciparum with coincident Salmonella Typhi bacteraemia without rheumatoid or autoimmune factors. Rapid diagnostic test false positivity for malaria coincided with the presence or absence of Salmonella Typhi in the blood. Clinicians should be aware that Salmonella Typhi infection may result in a false positive malaria rapid diagnostic test. The mechanism of this cross-reactivity is not clear.

A novel gamma-fitting statistical method for anti-drug antibody assays to establish assay cut points for data with non-normal distribution.

PubMed

Schlain, Brian; Amaravadi, Lakshmi; Donley, Jean; Wickramasekera, Ananda; Bennett, Donald; Subramanyam, Meena

2010-01-31

In recent years there has been growing recognition of the impact of anti-drug or anti-therapeutic antibodies (ADAs, ATAs) on the pharmacokinetic and pharmacodynamic behavior of the drug, which ultimately affects drug exposure and activity. These anti-drug antibodies can also impact safety of the therapeutic by inducing a range of reactions from hypersensitivity to neutralization of the activity of an endogenous protein. Assessments of immunogenicity, therefore, are critically dependent on the bioanalytical method used to test samples, in which a positive versus negative reactivity is determined by a statistically derived cut point based on the distribution of drug naïve samples. For non-normally distributed data, a novel gamma-fitting method for obtaining assay cut points is presented. Non-normal immunogenicity data distributions, which tend to be unimodal and positively skewed, can often be modeled by 3-parameter gamma fits. Under a gamma regime, gamma based cut points were found to be more accurate (closer to their targeted false positive rates) compared to normal or log-normal methods and more precise (smaller standard errors of cut point estimators) compared with the nonparametric percentile method. Under a gamma regime, normal theory based methods for estimating cut points targeting a 5% false positive rate were found in computer simulation experiments to have, on average, false positive rates ranging from 6.2 to 8.3% (or positive biases between +1.2 and +3.3%) with bias decreasing with the magnitude of the gamma shape parameter. The log-normal fits tended, on average, to underestimate false positive rates with negative biases as large a -2.3% with absolute bias decreasing with the shape parameter. These results were consistent with the well known fact that gamma distributions become less skewed and closer to a normal distribution as their shape parameters increase. Inflated false positive rates, especially in a screening assay, shifts the emphasis to confirm test results in a subsequent test (confirmatory assay). On the other hand, deflated false positive rates in the case of screening immunogenicity assays will not meet the minimum 5% false positive target as proposed in the immunogenicity assay guidance white papers. Copyright 2009 Elsevier B.V. All rights reserved.

Negative affect promotes encoding of and memory for details at the expense of the gist: affect, encoding, and false memories.

PubMed

Storbeck, Justin

2013-01-01

I investigated whether negative affective states enhance encoding of and memory for item-specific information reducing false memories. Positive, negative, and neutral moods were induced, and participants then completed a Deese-Roediger-McDermott (DRM) false-memory task. List items were presented in unique spatial locations or unique fonts to serve as measures for item-specific encoding. The negative mood conditions had more accurate memories for item-specific information, and they also had fewer false memories. The final experiment used a manipulation that drew attention to distinctive information, which aided learning for DRM words, but also promoted item-specific encoding. For the condition that promoted item-specific encoding, false memories were reduced for positive and neutral mood conditions to a rate similar to that of the negative mood condition. These experiments demonstrated that negative affective cues promote item-specific processing reducing false memories. People in positive and negative moods encode events differently creating different memories for the same event.

True detection limits in an experimental linearly heteroscedastic system. Part 1

NASA Astrophysics Data System (ADS)

Voigtman, Edward; Abraham, Kevin T.

2011-11-01

Using a lab-constructed laser-excited filter fluorimeter deliberately designed to exhibit linearly heteroscedastic, additive Gaussian noise, it has been shown that accurate estimates may be made of the true theoretical Currie decision levels ( YC and XC) and true Currie detection limits ( YD and XD) for the detection of rhodamine 6 G tetrafluoroborate in ethanol. The obtained experimental values, for 5% probability of false positives and 5% probability of false negatives, were YC = 56.1 mV, YD = 125. mV, XC = 0.132 μg /mL and XD = 0.294 μg /mL. For 5% probability of false positives and 1% probability of false negatives, the obtained detection limits were YD = 158. mV and XD = 0.372 μg /mL. These decision levels and corresponding detection limits were shown to pass the ultimate test: they resulted in observed probabilities of false positives and false negatives that were statistically equivalent to the a priori specified values.

A False Positive Dengue Fever Rapid Diagnostic Test Result in a Case of Acute Parvovirus B19 Infection.

PubMed

Izumida, Toshihide; Sakata, Hidenao; Nakamura, Masahiko; Hayashibara, Yumiko; Inasaki, Noriko; Inahata, Ryo; Hasegawa, Sumiyo; Takizawa, Takenori; Kaya, Hiroyasu

2016-01-01

An outbreak of dengue fever occurred in Japan in August 2014. We herein report the case of a 63-year-old man who presented with a persistent fever in September 2014. Acute parvovirus B19 infection led to a false positive finding of dengue fever on a rapid diagnostic test (Panbio Dengue Duo Cassette(TM)). To the best of our knowledge, there are no previous reports of a false positive result for dengue IgM with the dengue rapid diagnostic test. We believe that epidemiological information on the prevalence of parvovirus B19 is useful for guiding the interpretation of a positive result with the dengue rapid diagnostic test.

Wavelet method for CT colonography computer-aided polyp detection.

PubMed

Li, Jiang; Van Uitert, Robert; Yao, Jianhua; Petrick, Nicholas; Franaszek, Marek; Huang, Adam; Summers, Ronald M

2008-08-01

Computed tomographic colonography (CTC) computer aided detection (CAD) is a new method to detect colon polyps. Colonic polyps are abnormal growths that may become cancerous. Detection and removal of colonic polyps, particularly larger ones, has been shown to reduce the incidence of colorectal cancer. While high sensitivities and low false positive rates are consistently achieved for the detection of polyps sized 1 cm or larger, lower sensitivities and higher false positive rates occur when the goal of CAD is to identify "medium"-sized polyps, 6-9 mm in diameter. Such medium-sized polyps may be important for clinical patient management. We have developed a wavelet-based postprocessor to reduce false positives for this polyp size range. We applied the wavelet-based postprocessor to CTC CAD findings from 44 patients in whom 45 polyps with sizes of 6-9 mm were found at segmentally unblinded optical colonoscopy and visible on retrospective review of the CT colonography images. Prior to the application of the wavelet-based postprocessor, the CTC CAD system detected 33 of the polyps (sensitivity 73.33%) with 12.4 false positives per patient, a sensitivity comparable to that of expert radiologists. Fourfold cross validation with 5000 bootstraps showed that the wavelet-based postprocessor could reduce the false positives by 56.61% (p <0.001), to 5.38 per patient (95% confidence interval [4.41, 6.34]), without significant sensitivity degradation (32/45, 71.11%, 95% confidence interval [66.39%, 75.74%], p=0.1713). We conclude that this wavelet-based postprocessor can substantially reduce the false positive rate of our CTC CAD for this important polyp size range.

'It's the way that you look at it'--a cognitive neuropsychological account of SSRI action in depression.

PubMed

Harmer, Catherine J; Cowen, Philip J

2013-01-01

The fact that selective serotonin reuptake inhibitors (SSRIs) have antidepressant effects in some patients supports the notion that serotonin plays a role in the mode of action of antidepressant drugs. However, neither the way in which serotonin may alleviate depressed mood  nor the reason why several weeks needs to elapse before the full antidepressant effect of treatment is expressed  is known. Here, we propose a neuropsychological theory of SSRI antidepressant action based on the ability of SSRIs to produce positive biases in the processing of emotional information. Both behavioural and neuroimaging studies show that SSRI administration produces positive biases in attention, appraisal and memory from the earliest stages of treatment, well before the time that clinical improvement in mood becomes apparent. We suggest that the delay in the clinical effect of SSRIs can be explained by the time needed for this positive bias in implicit emotional processing to become apparent at a subjective, conscious level. This process is likely to involve the re-learning of emotional associations in a new, more positive emotional environment. This suggests intriguing links between the effect of SSRIs to promote synaptic plasticity and neurogenesis, and their ability to remediate negative emotional biases in depressed patients.

Orbital Epstein-Barr Virus-Positive Polymorphic B-Cell Lymphoproliferative Disorder in an Apparently Immunocompetent Woman.

PubMed

Abendroth, Michael D; Bayerl, Michael G; Wilkinson, Michael J; Claxton, David F; Specht, Charles S

2017-12-01

We report a rare case of Epstein-Barr virus (EBV)-positive polymorphic B-cell lymphoproliferative disorder (LPD) involving the lacrimal gland of a 28-year-old, apparently immunocompetent woman. She presented with a chief complaint of orbital swelling and tenderness and was found to have a lesion involving the right lacrimal gland and distal superior and lateral rectus muscles. Histology of the lesion revealed histiocytes with pleomorphic nuclei, reactive lymphocytes, and scattered cells that resembled the Reed-Sternberg (R-S) cells of classical Hodgkin lymphoma. The R-S-like cells were positive for PAX5 and CD30 and negative for CD15, supporting a diagnosis of polymorphic B-cell LPD. In situ hybridization for EBV-encoded RNA demonstrated the presence of EBV. Most EBV-positive polymorphic B-cell LPDs are associated with immunodeficiency. However, the patient described is HIV-negative and has no identifiable defects in immunoglobulin levels or cell-mediated immunity. This raises the question of whether she has an underlying immunodeficiency resulting from subtle changes in T-cell physiology, or whether chronic EBV infection contributed to her immune dysfunction through an unclear mechanism. The orbital mass partially regressed with chemotherapy, and the patient has done well clinically with no recurrence of this EBV-LPD for over 2 years.

The role of whole-body bone scanning and clinical factors in detecting bone metastases in patients with non-small cell lung cancer.

PubMed

Erturan, Serdar; Yaman, Mustafa; Aydin, Günay; Uzel, Isil; Müsellim, Benan; Kaynak, Kamil

2005-02-01

Correct detection of bone metastases in patients with non-small cell lung cancer (NSCLC) is crucial for prognosis and selection of an appropriate treatment regimen. The aim of this study was to investigate the role of whole-body bone scanning (WBBS) and clinical factors in detecting bone metastases in NSCLC. One hundred twenty-five patients with a diagnosis made between 1998 and 2002 were recruited (squamous cell carcinoma, 54.4%; adenocarcinoma, 32.8%; non-small cell carcinoma, 8.8%; large cell carcinoma, 4%). Clinical factors suggesting bone metastasis (skeletal pain, elevated alkaline phosphatase, hypercalcemia) were evaluated. WBBS was performed in all patients, and additional MRI was ordered in 10 patients because of discordance between clinical factors and WBBS findings. Bone metastases were detected in 53% (n = 21) of 39 clinical factor-positive patients, 5.8% (n = 5) of 86 clinical factor-negative patients, and 20.8% of total patients. The existence of bone-specific clinical factors as indicators of metastasis presented 53.8% positive predictive value (PPV), 94.2% negative predictive value (NPV), and 81.6% accuracy. However, the findings of WBBS showed 73.5% PPV, 97.8% NPV, and 91.2% accuracy. Adenocarcinoma was the most common cell type found in patients with bone metastasis (39%). The routine bone scanning prevented two futile thoracotomies (8%) in 25 patients with apparently operable lung cancer. In spite of the high NPV of the bone-specific clinical factors and the high value obtained in the false-positive findings in the bone scan, the present study indicates that in patients for whom surgical therapy is an option, preoperative staging using WBBS can be helpful to avoid misstaging due to asymptomatic bone metastases.

Diagnostic classification of macular ganglion cell and retinal nerve fiber layer analysis: differentiation of false-positives from glaucoma.

PubMed

Kim, Ko Eun; Jeoung, Jin Wook; Park, Ki Ho; Kim, Dong Myung; Kim, Seok Hwan

2015-03-01

To investigate the rate and associated factors of false-positive diagnostic classification of ganglion cell analysis (GCA) and retinal nerve fiber layer (RNFL) maps, and characteristic false-positive patterns on optical coherence tomography (OCT) deviation maps. Prospective, cross-sectional study. A total of 104 healthy eyes of 104 normal participants. All participants underwent peripapillary and macular spectral-domain (Cirrus-HD, Carl Zeiss Meditec Inc, Dublin, CA) OCT scans. False-positive diagnostic classification was defined as yellow or red color-coded areas for GCA and RNFL maps. Univariate and multivariate logistic regression analyses were used to determine associated factors. Eyes with abnormal OCT deviation maps were categorized on the basis of the shape and location of abnormal color-coded area. Differences in clinical characteristics among the subgroups were compared. (1) The rate and associated factors of false-positive OCT maps; (2) patterns of false-positive, color-coded areas on the GCA deviation map and associated clinical characteristics. Of the 104 healthy eyes, 42 (40.4%) and 32 (30.8%) showed abnormal diagnostic classifications on any of the GCA and RNFL maps, respectively. Multivariate analysis revealed that false-positive GCA diagnostic classification was associated with longer axial length and larger fovea-disc angle, whereas longer axial length and smaller disc area were associated with abnormal RNFL maps. Eyes with abnormal GCA deviation map were categorized as group A (donut-shaped round area around the inner annulus), group B (island-like isolated area), and group C (diffuse, circular area with an irregular inner margin in either). The axial length showed a significant increasing trend from group A to C (P=0.001), and likewise, the refractive error was more myopic in group C than in groups A (P=0.015) and B (P=0.014). Group C had thinner average ganglion cell-inner plexiform layer thickness compared with other groups (group A=B>C, P=0.004). Abnormal OCT diagnostic classification should be interpreted with caution, especially in eyes with long axial lengths, large fovea-disc angles, and small optic discs. Our findings suggest that the characteristic patterns of OCT deviation map can provide useful clues to distinguish glaucomatous changes from false-positive findings. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

A report of two cases of Al-Awadi Raas-Rothschild syndrome (AARRS) supporting that "apparent" Phocomelia differentiates AARRS from Schinzel Phocomelia syndrome (SPS).

PubMed

AlQattan, Mohammad M; AlAbdulkareem, Ibrahim; Ballow, Mariam; Al Balwi, Mohammed

2013-09-15

Although there is a long list of syndromes with phocomelia, there are only two syndromes in which there is concurrent pelvic dysplasia and phocomelia: Al-Awadi-Raas-Rothschild syndrome (AARRS) and Schinzel phocomelia syndrome (SPS). Currently, there is a diagnostic confusion between the two syndromes and both have the same MIM entry (MIM 276820). We believe that the two syndromes are different entities and we also believe that the limb defect in SPS is a "true" phocomelia while the limb defect in AARRS is an "apparent" phocomelia. "Apparent" phocomelia describes the most severe form of ulnar ray deficiency in which there is absent ulna with radio-humeral synostosis. "Apparent" phocomelia is diagnosed radiologically by three radiological features: the apparently single bone occupying the arm/forearm appears relatively long, the area of radio-humeral synostosis will have thicker cortex with or without slight angulation, and the lower end of the bone resembles the lower end of a radius and not a humerus. In this paper, we present two new cases of AARRS from two different Saudi Arabian tribes: one case with R292C mutation of WNT7A with bilateral "apparent" phocomelia and a second case with a novel c.814G>T mutation of the WNT7A gene (resulting in wnt7a protein truncation at position 272) with unilateral "apparent" phocomelia. We reviewed previously reported cases of AARRS and SPS to further delineate the differences between these two syndromes. We make the argument that these two syndromes are two different entities and hence require two different MIM entries. Copyright © 2013 Elsevier B.V. All rights reserved.

Mobile chemical detector (AP2C+SP4E) as an aid for medical decision making in the battlefield.

PubMed

Eisenkraft, Arik; Markel, Gal; Simovich, Shirley; Layish, Ido; Hoffman, Azik; Finkelstein, Arseny; Rotman, Eran; Dushnitsky, Tsvika; Krivoy, Amir

2007-09-01

The combination of the AP2C unit with the SP4E kit composes a lightweight mobile detector of chemical warfare agents (CWA), such as nerve and mustard agents, with both vapor- and liquid-sampling capabilities. This apparatus was recently introduced into our military medical units as an aid for detection of CWA on casualties. Importantly, critical information regarding the applicability in the battlefield was absent. In view of the serious consequences that might follow a proclamation of CWA recognition in battlefield, a high false-positive rate positions the utilization of this apparatus as a medical decision tool in question. We have therefore conducted a field experiment to test the false-positive rate as well as analyze possible factors leading to false-positive readings with this device. The experiment was carried out before and after a 4-day army field exercise, using a standard AP2C device, a SP4E surface sampling kit, and a specially designed medical sampling kit for casualties, intended for medical teams. Soldiers were examined at rest, after mild exercise, and after 4 days in the field. The readings with AP2C alone were compared to the combination of AP2C and SP4E and to the medical sampling kit. Various body fluids served as negative controls. Remarkably, we found a false-positive rate of 57% at rest and after mild exercise, and an even higher rate of 64% after the 4-day field exercise with the AP2C detector alone, as compared to almost no false-positive readings with the combination of AP2C and SP4E. Strikingly, the medical sampling kit has yielded numerous false-positive readings, even in normal body fluids such as blood, urine, and saliva. We therefore see no place for using the medical sampling kit due to an unaccepted high rate of false-positive readings. Finally, we have designed an algorithm that uses the entire apparatus of AP2C and SP4E as a reliable validation tool for medical triage in the setting of exposure to nerve agents in the battlefield.

Shaping memory accuracy by left prefrontal transcranial direct current stimulation.

PubMed

Zwissler, Bastian; Sperber, Christoph; Aigeldinger, Sina; Schindler, Sebastian; Kissler, Johanna; Plewnia, Christian

2014-03-12

Human memory is dynamic and flexible but is also susceptible to distortions arising from adaptive as well as pathological processes. Both accurate and false memory formation require executive control that is critically mediated by the left prefrontal cortex (PFC). Transcranial direct current stimulation (tDCS) enables noninvasive modulation of cortical activity and associated behavior. The present study reports that tDCS applied to the left dorsolateral PFC (dlPFC) shaped accuracy of episodic memory via polaritiy-specific modulation of false recognition. When applied during encoding of pictures, anodal tDCS increased whereas cathodal stimulation reduced the number of false alarms to lure pictures in subsequent recognition memory testing. These data suggest that the enhancement of excitability in the dlPFC by anodal tDCS can be associated with blurred detail memory. In contrast, activity-reducing cathodal tDCS apparently acted as a noise filter inhibiting the development of imprecise memory traces and reducing the false memory rate. Consistently, the largest effect was found in the most active condition (i.e., for stimuli cued to be remembered). This first evidence for a polarity-specific, activity-dependent effect of tDCS on false memory opens new vistas for the understanding and potential treatment of disturbed memory control.

Method for Correcting Control Surface Angle Measurements in Single Viewpoint Photogrammetry

NASA Technical Reports Server (NTRS)

Burner, Alpheus W. (Inventor); Barrows, Danny A. (Inventor)

2006-01-01

A method of determining a corrected control surface angle for use in single viewpoint photogrammetry to correct control surface angle measurements affected by wing bending. First and second visual targets are spaced apart &om one another on a control surface of an aircraft wing. The targets are positioned at a semispan distance along the aircraft wing. A reference target separation distance is determined using single viewpoint photogrammetry for a "wind off condition. An apparent target separation distance is then computed for "wind on." The difference between the reference and apparent target separation distances is minimized by recomputing the single viewpoint photogrammetric solution for incrementally changed values of target semispan distances. A final single viewpoint photogrammetric solution is then generated that uses the corrected semispan distance that produced the minimized difference between the reference and apparent target separation distances. The final single viewpoint photogrammetric solution set is used to determine the corrected control surface angle.

Flight investigation of the effect of control centering springs on the apparent spiral stability of a personal-owner airplane

NASA Technical Reports Server (NTRS)

Campbell, John P; Hunter, Paul A; Hewes, Donald E; Whitten, James B

1952-01-01

Report presents the results of a flight investigation conducted on a typical high-wing personal-owner airplane to determine the effect of control centering springs on apparent spiral stability. Apparent spiral stability is the term used to describe the spiraling tendencies of an airplane in uncontrolled flight as affected both by the true spiral stability of the perfectly trimmed airplane and by out-of-trim control settings. Centering springs were used in both the aileron and rudder control systems to provide both a positive centering action and a means of trimming the airplane. The springs were preloaded so that when they were moved through neutral they produced a nonlinear force gradient sufficient to overcome the friction in the control surface at the proper setting for trim. The ailerons and rudder control surfaces did not have trim tabs that could be adjusted in flight.

False Positive and False Negative Effects on Network Attacks

NASA Astrophysics Data System (ADS)

Shang, Yilun

2018-01-01

Robustness against attacks serves as evidence for complex network structures and failure mechanisms that lie behind them. Most often, due to detection capability limitation or good disguises, attacks on networks are subject to false positives and false negatives, meaning that functional nodes may be falsely regarded as compromised by the attacker and vice versa. In this work, we initiate a study of false positive/negative effects on network robustness against three fundamental types of attack strategies, namely, random attacks (RA), localized attacks (LA), and targeted attack (TA). By developing a general mathematical framework based upon the percolation model, we investigate analytically and by numerical simulations of attack robustness with false positive/negative rate (FPR/FNR) on three benchmark models including Erdős-Rényi (ER) networks, random regular (RR) networks, and scale-free (SF) networks. We show that ER networks are equivalently robust against RA and LA only when FPR equals zero or the initial network is intact. We find several interesting crossovers in RR and SF networks when FPR is taken into consideration. By defining the cost of attack, we observe diminishing marginal attack efficiency for RA, LA, and TA. Our finding highlights the potential risk of underestimating or ignoring FPR in understanding attack robustness. The results may provide insights into ways of enhancing robustness of network architecture and improve the level of protection of critical infrastructures.

Optimization of reverse chemical ecology method: false positive binding of Aenasius bambawalei odorant binding protein 1 caused by uncertain binding mechanism.

PubMed

Li, Q L; Yi, S C; Li, D Z; Nie, X P; Li, S Q; Wang, M-Q; Zhou, A M

2018-06-01

Odorant binding proteins (OBPs) are considered as the core molecular targets in reverse chemical ecology, which is a convenient and efficient method by which to screen potential semiochemicals. Herein, we identified a classic OBP, AbamOBP1 from Aenasius bambawalei, which showed high mRNA expression in male antennae. Fluorescence competitive binding assay (FCBA) results demonstrated that AbamOBP1 has higher binding affinity with ligands at acid pH, suggesting the physiologically inconsistent binding affinity of this protein. Amongst the four compounds with the highest binding affinities at acid pH, 2, 4, 4-trimethyl-2-pentene and 1-octen-3-one were shown to have attractant activity for male adults, whereas (-)-limonene and an analogue of 1-octen-3-ol exhibited nonbehavioural activity. Further homology modelling and fluorescence quenching experiments demonstrated that the stoichiometry of the binding of this protein to these ligands was not 1: 1, suggesting that the results of FCBA were false. In contrast, the apparent association constants (Ka) of fluorescence quenching experiments seemed to be more reliable, because 2, 4, 4-trimethyl-2-pentene and 1-octen-3-one had observably higher Ka than (-)-limonene and 1-octen-3-ol at neutral pH. Based on the characteristics of different OBPs, various approaches should be applied to study their binding affinities with ligands, which could modify and complement the results of FCBA and contribute to the application of reverse chemical ecology. © 2018 The Royal Entomological Society.

Size and Ultrasound Features Affecting Results of Ultrasound-Guided Fine-Needle Aspiration of Thyroid Nodules.

PubMed

Dong, YiJie; Mao, MinJing; Zhan, WeiWei; Zhou, JianQiao; Zhou, Wei; Yao, JieJie; Hu, YunYun; Wang, Yan; Ye, TingJun

2018-06-01

Our goal was to assess the diagnostic efficacy of ultrasound (US)-guided fine-needle aspiration (FNA) of thyroid nodules according to size and US features. A retrospective correlation was made with 1745 whole thyroidectomy and hemithyroidectomy specimens with preoperative US-guided FNA results. All cases were divided into 5 groups according to nodule size (≤5, 5.1-10, 10.1-15, 15.1-20, and >20 mm). For target nodules, static images and cine clips of conventional US and color Doppler were obtained. Ultrasound images were reviewed and evaluated by two radiologists with at least 5 years US working experience without knowing the results of pathology, and then agreement was achieved. The Bethesda category I rate was higher in nodules larger than 15 mm (P < .05). The diagnostic accuracy was best in nodules of 5 to 10 mm in diameter. The sensitivity, accuracy, PPV, and LR for negative US-guided FNA results were better in nodules with a size range of 5 to 15 mm. The specificity, negative predictive value (NPV), and LR for positive results and the Youden index rose with increasing nodule size. Seventeen false-positive and 60 false-negative results were found in this study. The false-negative rate rose with increasing nodule size. However, the false-positive rate was highest in the group containing the smallest nodules. Nodules with circumscribed margins and those that were nonsolid and nonhypoechoic and had no microcalcifications correlated with Bethesda I FNA results. Nodules with circumscribed margins and those that were nonsolid, heterogeneous, and nonhypoechoic and had increased vascularity correlated with false-negative FNA results. Borders correlated with Bethesda I false-negative and false-positive FNA results. Tiny nodules (≤5 mm) with obscure borders tended to yield false-positive FNA results. Large nodules (>20 mm) with several US features tended to yield false-negative FNA results. © 2017 by the American Institute of Ultrasound in Medicine.

Neural events that underlie remembering something that never happened.

PubMed

Gonsalves, B; Paller, K A

2000-12-01

We induced people to experience a false-memory illusion by first asking them to visualize common objects when cued with the corresponding word; on some trials, a photograph of the object was presented 1800 ms after the cue word. We then tested their memory for the photographs. Posterior brain potentials in response to words at encoding were more positive if the corresponding object was later falsely remembered as a photograph. Similar brain potentials during the memory test were more positive for true than for false memories. These results implicate visual imagery in the generation of false memories and provide neural correlates of processing differences between true and false memories.

Likelihood of early detection of breast cancer in relation to false-positive risk in life-time mammographic screening: population-based cohort study.

PubMed

Otten, J D M; Fracheboud, J; den Heeten, G J; Otto, S J; Holland, R; de Koning, H J; Broeders, M J M; Verbeek, A L M

2013-10-01

Women require balanced, high-quality information when making an informed decision on screening benefits and harms before attending biennial mammographic screening. The cumulative risk of a false-positive recall and/or (small) screen-detected or interval cancer over 13 consecutive screening examinations for women aged 50 from the start of screening were estimated using data from the Nijmegen programme, the Netherlands. Women who underwent 13 successive screens in the period 1975-1976 had a 5.3% cumulative chance of a screen-detected cancer, with a 4.2% risk of at least one false-positive recall. The risk of being diagnosed with interval cancer was 3.7%. Two decades later, these estimates were 6.9%, 7.3% and 2.9%, respectively. The chance of detection of a small, favourable invasive breast cancer, anticipating a normal life-expectancy, rose from 2.3% to 3.7%. Extrapolation to digital screening mammography indicates that the proportion of false-positive results will rise to 16%. Dutch women about to participate in the screening programme can be reassured that the chance of false-positive recall in the Netherlands is relatively low. A new screening policy and improved mammography have increased the detection of an early screening carcinoma and lowering the risk of interval carcinoma.

False-positive results in pharmacoepidemiology and pharmacovigilance.

PubMed

Bezin, Julien; Bosco-Levy, Pauline; Pariente, Antoine

2017-09-01

False-positive constitute an important issue in scientific research. In the domain of drug evaluation, it affects all phases of drug development and assessment, from the very early preclinical studies to the late post-marketing evaluations. The core concern associated with this false-positive is the lack of replicability of the results. Aside from fraud or misconducts, false-positive is often envisioned from the statistical angle, which considers them as a price to pay for type I error in statistical testing, and its inflation in the context of multiple testing. If envisioning this problematic in the context of pharmacoepidemiology and pharmacovigilance however, that both evaluate drugs in an observational settings, information brought by statistical testing and the significance of such should only be considered as additional to the estimates provided and their confidence interval, in a context where differences have to be a clinically meaningful upon everything, and the results appear robust to the biases likely to have affected the studies. In the following article, we consequently illustrate these biases and their consequences in generating false-positive results, through studies and associations between drug use and health outcomes that have been widely disputed. Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

Discordant HIV Test Results: Implications on Perinatal and Haemotransfusion Screening for HIV Infection, Cape Coast, Ghana.

PubMed

Tetteh, Ato Kwamena; Agyarko, Edward

2017-01-01

Screening results of 488 pregnant women aged 15-44 years whose blood samples had been tested on-site, using First Response® HIV 1/2, and confirmed with INNO-LIA™ HIV I/II Score were used. Of this total, 178 were reactive (HIV I, 154; HIV II, 2; and HIV I and HIV II, 22). Of the 154 HIV I-reactive samples, 104 were confirmed to be HIV I-positive and 2 were confirmed to be HIV II-positive, while 48 were confirmed to be negative [false positive rate = 17.44% (13.56-21.32)]. The two HIV II samples submitted were confirmed to be negative with the confirmatory test. For the 22 HIV I and HIV II samples, 7 were confirmed to be HIV I-positive and 1 was confirmed to be HIV I- and HIV II-positive, while 14 were confirmed to be negative. Of the 310 nonreactive samples, 6 were confirmed to be HIV I-positive and 1 was confirmed to be HIV II-positive [false negative rate = 5.79% (1.63-8.38)], while 303 were negative. False negative outcomes will remain unconfirmed, with no management options for the client. False negative rate of 5.79% requires attention, as its resultant implications on control of HIV/AIDS could be dire.

Misreporting signs of child abuse: the role of decision-making and outcome information.

PubMed

Lindholm, Torun; Sjöberg, Rickard L; Memon, Amina

2014-02-01

Two studies provided evidence that a decision to report an ambiguous case of child abuse affected subsequent memory of the case information, such that participants falsely recognized details that were not presented in the original information, but that are schematically associated with child abuse. Moreover, post-decision information that the child had later died from abuse influenced the memory reports of participants who had chosen not to report the case, increasing their reports of false schema-consistent details. This suggests that false decision-consistent memories are primarily due to sense-making, schematic processing rather than the motivation to justify the decision. The present findings points to an important mechanism by which decision information can become distorted in retrospect, and emphasize the difficulties of improving future decision-making by contemplating past decisions. The results also indicate that decisions may generate false memories in the apparent absence of external suggestion or misleading information. Implications for decision-making theory, and applied practices are discussed. © 2013 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Modification of two capripoxvirus quantitative real-time PCR assays to improve diagnostic sensitivity and include beta-actin as an internal positive control.

PubMed

Das, Amaresh; Deng, Ming Y; Babiuk, Shawn; McIntosh, Michael T

2017-05-01

Capripoxviruses (CaPVs), consisting of Sheeppox virus (SPV), Goatpox virus (GPV), and Lumpy skin disease virus (LSDV) species, cause economically significant diseases in sheep, goats, and cattle, respectively. Quantitative real-time polymerase chain reaction (qPCR) assays are routinely used for rapid detection of CaPVs in surveillance and outbreak management programs. We further modified and optimized 2 previously published CaPV qPCR assays, referred to as the Balinsky and Bowden assays, by changing commercial PCR reagents used in the tests. The modified assays displayed 100% analytical specificity and showed no apparent changes in analytical sensitivities for detection of CaPVs compared with the original assays. Diagnostic sensitivities, assessed using 50 clinical reference samples from experimentally infected sheep, goats, and cattle, improved from 82% to 92% for the modified Balinsky assay and from 58% to 82% for the modified Bowden assay. The modified qPCR assays were multiplexed for detection of beta-actin as an indicator for potential false-negative results. The multiplex modified qPCR assays exhibited the same diagnostic sensitivities as the singleplex assays suggesting their utility in the detection of CaPVs.

The Constellations of the Zodiac: Astronomy for Low Vision and Blind People

NASA Astrophysics Data System (ADS)

Garcia, B.; Cicero, A.; Farrando, M.; Bruno, P.

2006-08-01

One thinks, in general, there exist areas of the knowledge to which it is not possible to be acceded if one of the senses is diminished. Nevertheless, the reality is far from this false concept: it is not necessary to hear to compose music, nor to see to come near to the starred sky. This book has the purpose to introduce to the readers with visual difficulties the amazing world of astronomy, by means of the transmission of basic concepts of positional astronomy (cardinal points, Earth movements, apparent movement of the celestial sphere), with special emphasis in: movement of precession, the concept of stellar magnitude, its representation in celestial charts, and relation to mythology. On the other hand, the figures associated with the 13 constellations in the region of the plane of the ecliptic are described. The texts and the images are displayed in two formats: for visually diminished people, one worked on the basis of the original engravings of the Uranographia by Hevelius (1690). These were adapted and simplified for their better understanding, and a recommended font size. For blind people, we use tactile feature for the figures and Braille for the text.

Serological findings in leprosy and tuberculosis with the Wassermann, Meinicke, and VDRL tests.

PubMed

RUGE, H

1955-01-01

In the course of a venereal disease survey in Egypt, 820 cases of leprosy and 720 cases of tuberculosis were serologically examined with the Wassermann, Meinicke (MKR II), and VDRL tests; the results are reported in this paper.On serological and anamnestic evidence, 31 cases of syphilis were discovered among the leprosy cases and 37 among the tuberculosis cases. Apparently false positive reactions were seen in 203 cases of leprosy (25%) and in 38 cases of tuberculosis (5%). The author discusses the probability that a fairly high proportion of these reactions were in fact caused by otherwise undetected syphilis or were non-specific.The Meinicke test proved the most specific of the three, followed, in that order, by the Wassermann and the VDRL tests.It was found that syphilis was more frequent among males with tuberculosis than among those with leprosy; this is attributed to the fact that leprosy patients are kept in greater isolation. Less easily explicable is the fact that more females than males with leprosy were found to have syphilis, whereas in tuberculous persons the difference in syphilis incidence between male and female patients was not very great.

Theoretical Bounds for the Influence of Tissue-Level Ductility on the Apparent-Level Strength of Human Trabecular Bone

PubMed Central

Nawathe, Shashank; Juillard, Frédéric; Keaveny, Tony M.

2015-01-01

The role of tissue-level post-yield behavior on the apparent-level strength of trabecular bone is a potentially important aspect of bone quality. To gain insight into this issue, we compared the apparent-level strength of trabecular bone for the hypothetical cases of fully brittle versus fully ductile failure behavior of the trabecular tissue. Twenty human cadaver trabecular bone specimens (5 mm cube; BV/TV = 6–36%) were scanned with micro-CT to create 3D finite element models (22-micron element size). For each model, apparent-level strength was computed assuming either fully brittle (fracture with no tissue ductility) or fully ductile (yield with no tissue fracture) tissue-level behaviors. We found that the apparent-level ultimate strength for the brittle behavior was only about half the value of the apparent-level 0.2%-offset yield strength for the ductile behavior, and the ratio of these brittle to ductile strengths was almost constant (mean ± SD = 0.56 ± 0.02; n=20; R2 = 0.99 between the two measures). As a result of this small variation, although the ratio of brittle to ductile strengths was positively correlated with the bone volume fraction (R2=0.44, p=0.01) and structure model index (SMI, R2=0.58, p<0.01), these effects were small. Mechanistically, the fully ductile behavior resulted in a much higher apparent-level strength because in this case about 16-fold more tissue was required to fail than for the fully brittle behavior; also, there was more tensile- than compressive-mode of failure at the tissue level for the fully brittle behavior. We conclude that, in theory, the apparent-level strength behavior of human trabecular bone can vary appreciably depending on whether the tissue fails in a fully ductile versus fully brittle manner, and this effect is largely constant despite appreciable variations in bone volume fraction and microarchitecture. PMID:23497799

[Evaluation of performance of five bioinformatics software for the prediction of missense mutations].

PubMed

Chen, Qianting; Dai, Congling; Zhang, Qianjun; Du, Juan; Li, Wen

2016-10-01

To study the prediction performance evaluation with five kinds of bioinformatics software (SIFT, PolyPhen2, MutationTaster, Provean, MutationAssessor). From own database for genetic mutations collected over the past five years, Chinese literature database, Human Gene Mutation Database, and dbSNP, 121 missense mutations confirmed by functional studies, and 121 missense mutations suspected to be pathogenic by pedigree analysis were used as positive gold standard, while 242 missense mutations with minor allele frequency (MAF)>5% in dominant hereditary diseases were used as negative gold standard. The selected mutations were predicted with the five software. Based on the results, the performance of the five software was evaluated for their sensitivity, specificity, positive predict value, false positive rate, negative predict value, false negative rate, false discovery rate, accuracy, and receiver operating characteristic curve (ROC). In terms of sensitivity, negative predictive value and false negative rate, the rank was MutationTaster, PolyPhen2, Provean, SIFT, and MutationAssessor. For specificity and false positive rate, the rank was MutationTaster, Provean, MutationAssessor, SIFT, and PolyPhen2. For positive predict value and false discovery rate, the rank was MutationTaster, Provean, MutationAssessor, PolyPhen2, and SIFT. For area under the ROC curve (AUC) and accuracy, the rank was MutationTaster, Provean, PolyPhen2, MutationAssessor, and SIFT. The prediction performance of software may be different when using different parameters. Among the five software, MutationTaster has the best prediction performance.

Metal concentrations in oldsquaw (Clangula hyemalis) during an outbreak of avian cholera, Chesapeake Bay, 1994

USGS Publications Warehouse

Mashima, T.Y.; Fleming, W.J.; Stoskopf, M.K.

1998-01-01

Forty out of 41 oldsquaw carcasses collected during a 3 month avian cholera outbreak in Chesapeake Bay, USA, in 1994 were culture positive for Pasteurella multocida. Pasteurella-positive birds collected in February had greater (p ??? 0.05) mean (geometric) liver concentrations of cadmium (7.35 versus 3.71 ??g per g dry weight) and lower concentrations of selenium (9.90 versus 12.5 ??g per g dry weight) than Pasteurella-positive birds collected during March and April. The mercury content of the livers and cadmium content of the kidneys did not differ (p > 0.05) between birds collected early in the die-off and those collected in March and April. The liver and kidney concentrations of metals in the Pasteurella-positive birds collected in 1994 were compared to apparently healthy oldsquaw (n = 67) collected from Chesapeake Bay during 1985-1987, because healthy oldsquaw were not collected during the avian cholera outbreak in 1994. Compared to the apparently healthy oldsquaw collected in 1985-1987, the mean concentrations of cadmium (liver 4.32 versus 2.65 ??g per g dry weight and kidney 22.7 versus 11.5 ??g per g dry weight) were greater (p ??? 0.05) in the oldsquaw which succumbed to avian cholera in 1994. In contrast, the liver concentrations of selenium (11.9 versus 17.8 ??g per g dry weight) and mercury (0.389 versus 1.83 ??g per g dry weight) were lower (p ??? 0.05) in the birds from the 1994 die-off than for the apparently healthy oldsquaw collected in 1985-1987. Three birds from the 1985-1987 cohort and none of the birds from the 1994 cohort had liver lead concentrations greater than 4 ??g per g dry weight. The results of this study indicate a possible link between high cadmium tissue concentrations and susceptibility to avian cholera in oldsquaw.

Efficient detection of human circulating tumor cells without significant production of false-positive cells by a novel conditionally replicating adenovirus

PubMed Central

Sakurai, Fuminori; Narii, Nobuhiro; Tomita, Kyoko; Togo, Shinsaku; Takahashi, Kazuhisa; Machitani, Mitsuhiro; Tachibana, Masashi; Ouchi, Masaaki; Katagiri, Nobuyoshi; Urata, Yasuo; Fujiwara, Toshiyoshi; Mizuguchi, Hiroyuki

2016-01-01

Circulating tumor cells (CTCs) are promising biomarkers in several cancers, and thus methods and apparatuses for their detection and quantification in the blood have been actively pursued. A novel CTC detection system using a green fluorescence protein (GFP)–expressing conditionally replicating adenovirus (Ad) (rAd-GFP) was recently developed; however, there is concern about the production of false-positive cells (GFP-positive normal blood cells) when using rAd-GFP, particularly at high titers. In addition, CTCs lacking or expressing low levels of coxsackievirus–adenovirus receptor (CAR) cannot be detected by rAd-GFP, because rAd-GFP is constructed based on Ad serotype 5, which recognizes CAR. In order to suppress the production of false-positive cells, sequences perfectly complementary to blood cell–specific microRNA, miR-142-3p, were incorporated into the 3′-untranslated region of the E1B and GFP genes. In addition, the fiber protein was replaced with that of Ad serotype 35, which recognizes human CD46, creating rAdF35-142T-GFP. rAdF35-142T-GFP efficiently labeled not only CAR-positive tumor cells but also CAR-negative tumor cells with GFP. The numbers of false-positive cells were dramatically lower for rAdF35-142T-GFP than for rAd-GFP. CTCs in the blood of cancer patients were detected by rAdF35-142T-GFP with a large reduction in false-positive cells. PMID:26966699

Determining Binary Star Orbits Using Kepler's Equation

NASA Astrophysics Data System (ADS)

Boule, Cory; Andrews, Kaitlyn; Penfield, Andrew; Puckette, Ian; Goodale, Keith; Harfenist, Steven

2017-04-01

Students calculated ephemerides and generated orbits of four well-known binary systems. Using an iterative technique in Microsoft® Excel® to solve Kepler's equation, separation and position angle values were generated as well as plots of the apparent orbits. Current position angle and separation values were measured in the field and compared well to the calculated values for the stars: STF1196AB,C, STF296AB, STF296AB and STF60AB.

Distinguishing Binders from False Positives by Free Energy Calculations: Fragment Screening Against the Flap Site of HIV Protease

PubMed Central

2015-01-01

Molecular docking is a powerful tool used in drug discovery and structural biology for predicting the structures of ligand–receptor complexes. However, the accuracy of docking calculations can be limited by factors such as the neglect of protein reorganization in the scoring function; as a result, ligand screening can produce a high rate of false positive hits. Although absolute binding free energy methods still have difficulty in accurately rank-ordering binders, we believe that they can be fruitfully employed to distinguish binders from nonbinders and reduce the false positive rate. Here we study a set of ligands that dock favorably to a newly discovered, potentially allosteric site on the flap of HIV-1 protease. Fragment binding to this site stabilizes a closed form of protease, which could be exploited for the design of allosteric inhibitors. Twenty-three top-ranked protein–ligand complexes from AutoDock were subject to the free energy screening using two methods, the recently developed binding energy analysis method (BEDAM) and the standard double decoupling method (DDM). Free energy calculations correctly identified most of the false positives (≥83%) and recovered all the confirmed binders. The results show a gap averaging ≥3.7 kcal/mol, separating the binders and the false positives. We present a formula that decomposes the binding free energy into contributions from the receptor conformational macrostates, which provides insights into the roles of different binding modes. Our binding free energy component analysis further suggests that improving the treatment for the desolvation penalty associated with the unfulfilled polar groups could reduce the rate of false positive hits in docking. The current study demonstrates that the combination of docking with free energy methods can be very useful for more accurate ligand screening against valuable drug targets. PMID:25189630

Cumulative Incidence of False-Positive Results in Repeated, Multimodal Cancer Screening

PubMed Central

Croswell, Jennifer Miller; Kramer, Barnett S.; Kreimer, Aimee R.; Prorok, Phil C.; Xu, Jian-Lun; Baker, Stuart G.; Fagerstrom, Richard; Riley, Thomas L.; Clapp, Jonathan D.; Berg, Christine D.; Gohagan, John K.; Andriole, Gerald L.; Chia, David; Church, Timothy R.; Crawford, E. David; Fouad, Mona N.; Gelmann, Edward P.; Lamerato, Lois; Reding, Douglas J.; Schoen, Robert E.

2009-01-01

PURPOSE Multiple cancer screening tests have been advocated for the general population; however, clinicians and patients are not always well-informed of screening burdens. We sought to determine the cumulative risk of a false-positive screening result and the resulting risk of a diagnostic procedure for an individual participating in a multimodal cancer screening program. METHODS Data were analyzed from the intervention arm of the ongoing Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, a randomized controlled trial to determine the effects of prostate, lung, colorectal, and ovarian cancer screening on disease-specific mortality. The 68,436 participants, aged 55 to 74 years, were randomized to screening or usual care. Women received serial serum tests to detect cancer antigen 125 (CA-125), transvaginal sonograms, posteroanterior-view chest radiographs, and flexible sigmoidoscopies. Men received serial chest radiographs, flexible sigmoidoscopies, digital rectal examinations, and serum prostate-specific antigen tests. Fourteen screening examinations for each sex were possible during the 3-year screening period. RESULTS After 14 tests, the cumulative risk of having at least 1 false-positive screening test is 60.4% (95% CI, 59.8%–61.0%) for men, and 48.8% (95% CI, 48.1%–49.4%) for women. The cumulative risk after 14 tests of undergoing an invasive diagnostic procedure prompted by a false-positive test is 28.5% (CI, 27.8%–29.3%) for men and 22.1% (95% CI, 21.4%–22.7%) for women. CONCLUSIONS For an individual in a multimodal cancer screening trial, the risk of a false-positive finding is about 50% or greater by the 14th test. Physicians should educate patients about the likelihood of false positives and resulting diagnostic interventions when counseling about cancer screening. PMID:19433838

Female False Positive Exercise Stress ECG Testing - Fact Verses Fiction.

PubMed

Fitzgerald, Benjamin T; Scalia, William M; Scalia, Gregory M

2018-03-07

Exercise stress testing is a well validated cardiovascular investigation. Accuracy for treadmill stress electrocardiograph (ECG) testing has been documented at 60%. False positive stress ECGs (exercise ECG changes with non-obstructive disease on anatomical testing) are common, especially in women, limiting the effectiveness of the test. This study investigates the incidence and predictors of false positive stress ECG findings, referenced against stress echocardiography (SE) as a standard. Stress echocardiography was performed using the Bruce treadmill protocol. False positive stress ECG tests were defined as greater than 1mm of ST depression on ECG during exertion, without pain, with a normal SE. Potential causes for false positive tests were recorded before the test. Three thousand consecutive negative stress echocardiograms (1036 females, 34.5%) were analysed (age 59+/-14 years. False positive (F+) stress ECGs were documented in 565/3000 tests (18.8%). F+ stress ECGs were equally prevalent in females (194/1036, 18.7%) and males (371/1964, 18.9%, p=0.85 for the difference). Potential causes (hypertension, left ventricular hypertrophy, known coronary disease, arrhythmia, diabetes mellitus, valvular heart disease) were recorded in 36/194 (18.6%) of the female F+ ECG tests and 249/371 (68.2%) of the male F+ ECG tests (p<0.0001 for the difference). These data suggest that F+ stress ECG tests are frequent and equally common in women and men. However, most F+ stress ECGs in men can be predicted before the test, while most in women cannot. Being female may be a risk factor in itself. These data reinforce the value of stress imaging, particularly in women. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). All rights reserved.

Diagnostic value and cost utility analysis for urine Gram stain and urine microscopic examination as screening tests for urinary tract infection.

PubMed

Wiwanitkit, Viroj; Udomsantisuk, Nibhond; Boonchalermvichian, Chaiyaporn

2005-06-01

The aim of this study was to evaluate the diagnostic properties of urine Gram stain and urine microscopic examination for screening for urinary tract infection (UTI), and to perform an additional cost utility analysis. This descriptive study was performed on 95 urine samples sent for urine culture to the Department of Microbiology, Faculty of Medicine, Chulalongkorn University. The first part of the study was to determine the diagnostic properties of two screening tests (urine Gram stain and urine microscopic examination). Urine culture was set as the gold standard and the results from both methods were compared to this. The second part of this study was to perform a cost utility analysis. The sensitivity of urine Gram stain was 96.2%, the specificity 93.0%, the positive predictive value 94.3% and the negative predictive value 95.2%. False positives occurred with a frequency of 7.0% and false negatives 3.8%. For the microscopic examination, the sensitivity was 65.4%, specificity 74.4%, positive predictive value 75.6% and negative predictive value 64.0%. False positives occurred with a frequency of 25.6% and false negatives 34.6%. Combining urine Gram stain and urine microscopic examination, the sensitivity was 98.1%, specificity 74.4%, positive predictive value 82.3% and negative predictive value 97.0%. False positives occurred with a frequency of 25.6% and false negatives 1.9%. However, the cost per utility of the combined method was higher than either urine microscopic examination or urine Gram stain alone. Urine Gram stain provided the lowest cost per utility. Economically, urine Gram stain is the proper screening tool for presumptive diagnosis of UTI.

Placing symptoms in context: the role of contextual criteria in reducing false positives in Diagnostic and Statistical Manual of Mental Disorders diagnoses.

PubMed

Wakefield, Jerome C; First, Michael B

2012-02-01

The Diagnostic and Statistical Manual of Mental Disorders (DSM) definition of mental disorder requires that symptoms be caused by a dysfunction in the individual; when dysfunction is absent, symptoms represent normal-range distress or eccentricity and, if diagnosed as a mental disorder, are false positives. We hypothesized that because of psychiatry's lack of direct laboratory tests to distinguish dysfunction from normal-range distress, the context in which symptoms occur (eg, lack of imminent danger in a panic attack) is often essential to determining whether symptoms are caused by a dysfunction. If this is right, then the DSM diagnostic criteria should include many contextual criteria added to symptom syndromes to prevent dysfunction false positives. Despite their potential importance, such contextual criteria have not been previously reviewed. We, thus, systematically reviewed DSM categories to establish the extent of such uses of contextual criteria and created a typology of such uses. Of 111 sampled categories, 68 (61%) used context to prevent dysfunction false positives. Contextual criteria fell into 7 types: (1) exclusion of specific false-positive scenarios; (2) requiring that patients experience preconditions for normal responses (eg, requiring that individuals experience adequate sexual stimulation before being diagnosed with sexual dysfunctions); (3) requiring that symptoms be disproportionate relative to circumstances; (4) for childhood disorders, requiring that symptoms be developmentally inappropriate; (5) requiring that symptoms occur in multiple contexts; (6) requiring a substantial discrepancy between beliefs and reality; and (7) a residual category. Most DSM categories include contextual criteria to eliminate false-positive diagnoses and increase validity of descriptive criteria. Future revisions should systematically evaluate each category's need for contextual criteria. Copyright © 2012 Elsevier Inc. All rights reserved.

Reduction of false-positives in a CAD scheme for automated detection of architectural distortion in digital mammography

NASA Astrophysics Data System (ADS)

de Oliveira, Helder C. R.; Mencattini, Arianna; Casti, Paola; Martinelli, Eugenio; di Natale, Corrado; Catani, Juliana H.; de Barros, Nestor; Melo, Carlos F. E.; Gonzaga, Adilson; Vieira, Marcelo A. C.

2018-02-01

This paper proposes a method to reduce the number of false-positives (FP) in a computer-aided detection (CAD) scheme for automated detection of architectural distortion (AD) in digital mammography. AD is a subtle contraction of breast parenchyma that may represent an early sign of breast cancer. Due to its subtlety and variability, AD is more difficult to detect compared to microcalcifications and masses, and is commonly found in retrospective evaluations of false-negative mammograms. Several computer-based systems have been proposed for automated detection of AD in breast images. The usual approach is automatically detect possible sites of AD in a mammographic image (segmentation step) and then use a classifier to eliminate the false-positives and identify the suspicious regions (classification step). This paper focus on the optimization of the segmentation step to reduce the number of FPs that is used as input to the classifier. The proposal is to use statistical measurements to score the segmented regions and then apply a threshold to select a small quantity of regions that should be submitted to the classification step, improving the detection performance of a CAD scheme. We evaluated 12 image features to score and select suspicious regions of 74 clinical Full-Field Digital Mammography (FFDM). All images in this dataset contained at least one region with AD previously marked by an expert radiologist. The results showed that the proposed method can reduce the false positives of the segmentation step of the CAD scheme from 43.4 false positives (FP) per image to 34.5 FP per image, without increasing the number of false negatives.

The local lymph node assay: current position in the regulatory classification of skin sensitizing chemicals.

PubMed

Basketter, David A; Gerberick, G Frank; Kimber, Ian

2007-01-01

The local lymph node assay (LLNA) is being used increasingly in the identification of skin sensitizing chemicals for regulatory purposes. In the context of new chemicals legislation (REACH) in Europe, it is the preferred assay. The rationale for this is that the LLNA quantitative and objective approach to skin sensitization testing allied with the important animal welfare benefits that the method offers. However, as with certain guinea pig sensitization tests before it, this increasing use also brings experience with an increasingly wide range of industrial and other chemicals where the outcome of the assay does not always necessarily meet with the expectations of those conducting it. Sometimes, the result appears to be a false negative, but rather more commonly, the complaint is that the chemical represents a false positive. Against this background we have here reviewed a number of instances where false positive and false negative results have been described and have sought to reconcile science with expectation. Based on these analyses, it is our conclusion that false positives and false negatives do occur in the LLNA, as they do with any other skin sensitization assay (and indeed with all tests used for hazard identification), and that this occurs for a number of reasons. We further conclude, however, that false positive results in the LLNA, as with the guinea pig maximization test, arise most commonly via failure to distinguish what is scientifically correct from that which is unpalatable. The consequences of this confusion are discussed in the article, particularly in relation to the need to integrate both potency measurement and risk assessments into classification and labelling schemes that aim to manage potential risks to human health.

Determining Occurrence Dynamics when False Positives Occur: Estimating the Range Dynamics of Wolves from Public Survey Data.

PubMed

Miller, David A W; Nichols, James D; Gude, Justin A; Rich, Lindsey N; Podruzny, Kevin M; Hines, James E; Mitchell, Michael S

2013-01-01

Large-scale presence-absence monitoring programs have great promise for many conservation applications. Their value can be limited by potential incorrect inferences owing to observational errors, especially when data are collected by the public. To combat this, previous analytical methods have focused on addressing non-detection from public survey data. Misclassification errors have received less attention but are also likely to be a common component of public surveys, as well as many other data types. We derive estimators for dynamic occupancy parameters (extinction and colonization), focusing on the case where certainty can be assumed for a subset of detections. We demonstrate how to simultaneously account for non-detection (false negatives) and misclassification (false positives) when estimating occurrence parameters for gray wolves in northern Montana from 2007-2010. Our primary data source for the analysis was observations by deer and elk hunters, reported as part of the state's annual hunter survey. This data was supplemented with data from known locations of radio-collared wolves. We found that occupancy was relatively stable during the years of the study and wolves were largely restricted to the highest quality habitats in the study area. Transitions in the occupancy status of sites were rare, as occupied sites almost always remained occupied and unoccupied sites remained unoccupied. Failing to account for false positives led to over estimation of both the area inhabited by wolves and the frequency of turnover. The ability to properly account for both false negatives and false positives is an important step to improve inferences for conservation from large-scale public surveys. The approach we propose will improve our understanding of the status of wolf populations and is relevant to many other data types where false positives are a component of observations.

Unmodeled observation error induces bias when inferring patterns and dynamics of species occurrence via aural detections

USGS Publications Warehouse

McClintock, Brett T.; Bailey, Larissa L.; Pollock, Kenneth H.; Simons, Theodore R.

2010-01-01

The recent surge in the development and application of species occurrence models has been associated with an acknowledgment among ecologists that species are detected imperfectly due to observation error. Standard models now allow unbiased estimation of occupancy probability when false negative detections occur, but this is conditional on no false positive detections and sufficient incorporation of explanatory variables for the false negative detection process. These assumptions are likely reasonable in many circumstances, but there is mounting evidence that false positive errors and detection probability heterogeneity may be much more prevalent in studies relying on auditory cues for species detection (e.g., songbird or calling amphibian surveys). We used field survey data from a simulated calling anuran system of known occupancy state to investigate the biases induced by these errors in dynamic models of species occurrence. Despite the participation of expert observers in simplified field conditions, both false positive errors and site detection probability heterogeneity were extensive for most species in the survey. We found that even low levels of false positive errors, constituting as little as 1% of all detections, can cause severe overestimation of site occupancy, colonization, and local extinction probabilities. Further, unmodeled detection probability heterogeneity induced substantial underestimation of occupancy and overestimation of colonization and local extinction probabilities. Completely spurious relationships between species occurrence and explanatory variables were also found. Such misleading inferences would likely have deleterious implications for conservation and management programs. We contend that all forms of observation error, including false positive errors and heterogeneous detection probabilities, must be incorporated into the estimation framework to facilitate reliable inferences about occupancy and its associated vital rate parameters.

Best research practices in psychology: Illustrating epistemological and pragmatic considerations with the case of relationship science.

PubMed

Finkel, Eli J; Eastwick, Paul W; Reis, Harry T

2015-02-01

In recent years, a robust movement has emerged within psychology to increase the evidentiary value of our science. This movement, which has analogs throughout the empirical sciences, is broad and diverse, but its primary emphasis has been on the reduction of statistical false positives. The present article addresses epistemological and pragmatic issues that we, as a field, must consider as we seek to maximize the scientific value of this movement. Regarding epistemology, this article contrasts the false-positives-reduction (FPR) approach with an alternative, the error balance (EB) approach, which argues that any serious consideration of optimal scientific practice must contend simultaneously with both false-positive and false-negative errors. Regarding pragmatics, the movement has devoted a great deal of attention to issues that frequently arise in laboratory experiments and one-shot survey studies, but it has devoted less attention to issues that frequently arise in intensive and/or longitudinal studies. We illustrate these epistemological and pragmatic considerations with the case of relationship science, one of the many research domains that frequently employ intensive and/or longitudinal methods. Specifically, we examine 6 research prescriptions that can help to reduce false-positive rates: preregistration, prepublication sharing of materials, postpublication sharing of data, close replication, avoiding piecemeal publication, and increasing sample size. For each, we offer concrete guidance not only regarding how researchers can improve their research practices and balance the risk of false-positive and false-negative errors, but also how the movement can capitalize upon insights from research practices within relationship science to make the movement stronger and more inclusive. PsycINFO Database Record (c) 2015 APA, all rights reserved.

Influence of dental correction on nociceptive test responses, fecal appearance, body condition score, and apparent digestibility coefficient for dry matter of Zamorano-leones donkeys (Equus asinus).

PubMed

Rodrigues, J B; Ferreira, L M; Bastos, E; San Roman, F; Viegas, C; Santos, A S

2013-10-01

The influence of dental correction on nociceptive (pressure) test responses, fecal appearance, BCS, and apparent digestibility coefficient for DM was studied in 18 Zamorano-Leonés donkeys, an endangered local breed from the Zamora province in Spain. For this purpose, donkeys were divided into 2 homogeneous control and treatment groups, based on age, BCS, and dental findings. On d 1, 45, 90, and 135, BCS and nociceptive test responses were evaluated in all donkeys. Feed and fecal samples were collected from all donkeys for 3 consecutive days, starting at each of the aforementioned days. Apparent digestibility coefficient for DM was estimated, using ADL as an internal marker. A progressive decrease of positive nociceptive test responses was observed from d 1 up to 90 (P < 0.01) in the treatment group. No difference between groups was observed for BCS. However, BCS at d 90 was greater (P = 0.018) than observed on d 1 or 45, indicating a time influence. Concerning apparent digestibility coefficient for DM, there were differences among collection days in apparent digestibility coefficient for DM (P < 0.05). No differences in fecal appearance were observed between treatments or collection days. This study highlighted the importance of regular dental care for not only Zamorano-Leonés donkeys but also the equid population, in general, to improve their welfare.

Manipulating stereopsis and vergence in an outdoor setting: moon, sky and horizon.

PubMed

Enright, J T

1989-01-01

A simple stimulus generator has been constructed that permits a small illuminated target to be seen with variable inter-ocular disparity, when superimposed upon the binocular view of an outdoor landscape. This device was applied to several questions involving perception of size, distance and orientation, with the following results: (1) when the apparent distance to an "artificial moon", as perceived through stereopsis, is decreased by about 50-fold (from near horizon to about 60 m), its apparent size is reduced by only a miniscule amount (8% on average); hence, the moon illusion is probably not due to compensation--conscious or subconscious--for its apparent distance; (2) those changes in apparent size known as convergence micropsia vary as a function of the visual surround; for a vergence change of 1 deg, greater perceived change in size of a small target arises when a landscape is seen nearby than with empty sky as surround; (3) when a target is shown somewhat above the horizon against an empty sky, it must be viewed with divergence of the visual axes (image positions for "hyper-infinite" distance), in order to be perceived as vertically above objects on the skyline; this effect implies a strong backward tilt to the apparent vertical and probably reflects an attempt to "null out" the perceptual consequences of the convergence that typically occurs during downward saccades.

Apparent Diffusion Coefficient and Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Pancreatic Cancer: Characteristics and Correlation With Histopathologic Parameters.

PubMed

Ma, Wanling; Li, Na; Zhao, Weiwei; Ren, Jing; Wei, Mengqi; Yang, Yong; Wang, Yingmei; Fu, Xin; Zhang, Zhuoli; Larson, Andrew C; Huan, Yi

2016-01-01

To clarify diffusion and perfusion abnormalities and evaluate correlation between apparent diffusion coefficient (ADC), MR perfusion and histopathologic parameters of pancreatic cancer (PC). Eighteen patients with PC underwent diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Parameters of DCE-MRI and ADC of cancer and non-cancerous tissue were compared. Correlation between the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space (K, volume of the extravascular extracellular space per unit volume of tissue (Ve), and ADC of PC and histopathologic parameters were analyzed. The rate constant that represents transfer of contrast agent from the extravascular extracellular space into blood plasma, K, tissue volume fraction occupied by vascular space, and ADC of PC were significantly lower than nontumoral pancreases. Ve of PC was significantly higher than that of nontumoral pancreas. Apparent diffusion coefficient and K values of PC were negatively correlated to fibrosis content and fibroblast activation protein staining score. Fibrosis content was positively correlated to Ve. Apparent diffusion coefficient values and parameters of DCE-MRI can differentiate PC from nontumoral pancreases. There are correlations between ADC, K, Ve, and fibrosis content of PC. Fibroblast activation protein staining score of PC is negatively correlated to ADC and K. Apparent diffusion coefficient, K, and Ve may be feasible to predict prognosis of PC.

Are the memories of older adults positively biased?

PubMed

Fernandes, Myra; Ross, Michael; Wiegand, Melanie; Schryer, Emily

2008-06-01

There is disagreement in the literature about whether a "positivity effect" in memory performance exists in older adults. To assess the generalizability of the effect, the authors examined memory for autobiographical, picture, and word information in a group of younger (17-29 years old) and older (60-84 years old) adults. For the autobiographical memory task, the authors asked participants to produce 4 positive, 4 negative, and 4 neutral recent autobiographical memories and to recall these a week later. For the picture and word tasks, participants studied photos or words of different valences (positive, negative, neutral) and later remembered them on a free-recall test. The authors found significant correlations in memory performance, across task material, for recall of both positive and neutral valence autobiographical events, pictures, and words. When the authors examined accurate memories, they failed to find consistent evidence, across the different types of material, of a positivity effect in either age group. However, the false memory findings offer more consistent support for a positivity effect in older adults. During recall of all 3 types of material, older participants recalled more false positive than false negative memories.

A variable parameter single degree-of-freedom model for predicting the effects of sitting posture and vibration magnitude on the vertical apparent mass of the human body.

PubMed

Toward, Martin G R; Griffin, Michael J

2010-01-01

Models of the vertical apparent mass of the human body are mostly restricted to a sitting posture unsupported by a backrest and ignore the variations in apparent mass associated with changes in posture and changes in the magnitude of vibration. Using findings from experimental research, this study fitted a single degree-of-freedom lumped parameter model to the measured vertical apparent mass of the body measured with a range of sitting postures and vibration magnitudes. The resulting model reflects the effects of reclining a rigid backrest or reclining a foam backrest (from 0 to 30 degrees), the effects of moving the hands from the lap to a steering wheel, the effects of moving the horizontal position of the feet, and the effects of vibration magnitude (from 0.125 to 1.6 ms(-2) r.m.s.). The error between the modelled and the measured apparent mass was minimised, for both the apparent masses of individual subjects and the median apparent masses of groups of 12 subjects, for each sitting posture and each vibration magnitude. Trends in model parameters, the damping ratios, and the damped natural frequencies were identified as a function of the model variables and show the effects of posture and vibration magnitude on body dynamics. For example, contact with a rigid backrest increased the derived damped natural frequency of the principal resonance as a result of reduced moving mass and increased stiffness. When the rigid backrest was reclined from 0 to 30º, the damping decreased and the resonance frequency increased as a result of reduced moving mass. It is concluded that, by appropriate variations in model parameters, a single degree-of-freedom model can provide a useful fit to the vertical apparent mass of the human body over a wide range of postures and vibration magnitudes. When measuring or modelling seat transmissibility, it may be difficult to justify an apparent mass model with more than a single degree-of-freedom if it does not reflect the large influences of vibration magnitude, body posture, and individual variability.

Use of female nest characteristics in the sexual behaviour of male sockeye salmon

USGS Publications Warehouse

Hamon, T.R.; Foote, C.J.; Brown, G.S.

1999-01-01

On three island beaches in Iliamna Lake, Alaska, large numbers of male sockeye salmon gathered and spawned in artificial excavations that mimicked a female's nest immediately prior to spawning, while apparently ignoring the control site. The number of males attracted was correlated positively with changes in the operational sex ratio. In contrast, on the mainland beach examined, no reaction to the artificial nests was apparent. The results are discussed in terms of mate searching behaviour by males, the duration of the spawning period, and associated selection pressures on males to use characteristics of their environment that provide information on availability of females.

ON THE CONNECTION OF THE APPARENT PROPER MOTION AND THE VLBI STRUCTURE OF COMPACT RADIO SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moor, A.; Frey, S.; Lambert, S. B.

2011-06-15

Many of the compact extragalactic radio sources that are used as fiducial points to define the celestial reference frame are known to have proper motions detectable with long-term geodetic/astrometric very long baseline interferometry (VLBI) measurements. These changes can be as high as several hundred microarcseconds per year for certain objects. When imaged with VLBI at milliarcsecond (mas) angular resolution, these sources (radio-loud active galactic nuclei) typically show structures dominated by a compact, often unresolved 'core' and a one-sided 'jet'. The positional instability of compact radio sources is believed to be connected with changes in their brightness distribution structure. For themore » first time, we test this assumption in a statistical sense on a large sample rather than on only individual objects. We investigate a sample of 62 radio sources for which reliable long-term time series of astrometric positions as well as detailed 8 GHz VLBI brightness distribution models are available. We compare the characteristic direction of their extended jet structure and the direction of their apparent proper motion. We present our data and analysis method, and conclude that there is indeed a correlation between the two characteristic directions. However, there are cases where the {approx}1-10 mas scale VLBI jet directions are significantly misaligned with respect to the apparent proper motion direction.« less

Comparison of Biodynamic Responses in Standing and Seated Human Bodies

NASA Astrophysics Data System (ADS)

MATSUMOTO, Y.; GRIFFIN, M. J.

2000-12-01

The dynamic responses of the human body in a standing position and in a sitting position have been compared. The apparent mass and transmissibilities to the head, six locations along the spine, and the pelvis were measured with eight male subjects exposed to vertical whole-body vibration. In both postures, the principal resonance in the apparent mass occurred in the range 5-6 Hz, with slightly higher frequencies and lower apparent mass in the standing posture. There was greater transmission of vertical vibration to the pelvis and the lower spine and greater relative motion within the lower spine in the standing posture than in the sitting posture at the principal resonance and at higher frequencies. Transmissibilities from the supporting surface (floor or seat) to the thoracic region had similar magnitudes for both standing and sitting subjects. The lumbar spine has less lordosis and may be more compressed and less flexible in the sitting posture than in the standing posture. This may have reduced the relative motions between lumbar vertebrae and both the supporting vibrating surface and the other vertebrae in the sitting posture. The characteristics of the vibration transmitted to the pelvis may have differed in the two postures due to different transmission paths. Increased forward rotation of the pelvis in the standing posture may have caused the differences in responses of the pelvis and the lower spine that were observed between the two postures.

Standoff detection of chemical and biological threats using laser-induced breakdown spectroscopy.

PubMed

Gottfried, Jennifer L; De Lucia, Frank C; Munson, Chase A; Miziolek, Andrzej W

2008-04-01

Laser-induced breakdown spectroscopy (LIBS) is a promising technique for real-time chemical and biological warfare agent detection in the field. We have demonstrated the detection and discrimination of the biological warfare agent surrogates Bacillus subtilis (BG) (2% false negatives, 0% false positives) and ovalbumin (0% false negatives, 1% false positives) at 20 meters using standoff laser-induced breakdown spectroscopy (ST-LIBS) and linear correlation. Unknown interferent samples (not included in the model), samples on different substrates, and mixtures of BG and Arizona road dust have been classified with reasonable success using partial least squares discriminant analysis (PLS-DA). A few of the samples tested such as the soot (not included in the model) and the 25% BG:75% dust mixture resulted in a significant number of false positives or false negatives, respectively. Our preliminary results indicate that while LIBS is able to discriminate biomaterials with similar elemental compositions at standoff distances based on differences in key intensity ratios, further work is needed to reduce the number of false positives/negatives by refining the PLS-DA model to include a sufficient range of material classes and carefully selecting a detection threshold. In addition, we have demonstrated that LIBS can distinguish five different organophosphate nerve agent simulants at 20 meters, despite their similar stoichiometric formulas. Finally, a combined PLS-DA model for chemical, biological, and explosives detection using a single ST-LIBS sensor has been developed in order to demonstrate the potential of standoff LIBS for universal hazardous materials detection.

Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect

PubMed Central

Banks, Emily; Reeves, Gillian; Beral, Valerie; Bull, Diana; Crossley, Barbara; Simmonds, Moya; Hilton, Elizabeth; Bailey, Stephen; Barrett, Nigel; Briers, Peter; English, Ruth; Jackson, Alan; Kutt, Elizabeth; Lavelle, Janet; Rockall, Linda; Wallis, Matthew G; Wilson, Mary; Patnick, Julietta

2006-01-01

Introduction Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall. Methods A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome. Results Overall, 399 (0.5%) participants were diagnosed with breast cancer and 2,629 (3.0%) had false positive recall. Compared to never users of HRT, the adjusted relative risk (95% CI) of false positive recall was: 1.62 (1.43–1.83), 1.80 (1.62–2.01) and 0.76 (0.52–1.10) in current users of oestrogen-only HRT, oestrogen-progestagen HRT and tibolone, respectively (p (heterogeneity) < 0.0001); 1.65 (1.43–1.91), 1.49 (1.22–1.81) and 2.11 (1.45–3.07) for current HRT used orally, transdermally or via an implant, respectively (p (heterogeneity) = 0.2); and 1.84 (1.67–2.04) and 1.75 (1.49–2.06) for sequential and continuous oestrogen-progestagen HRT, respectively (p (heterogeneity) = 0.6). The relative risk of false positive recall among current users appeared to increase with increasing time since menopause, but did not vary significantly according to any other factors examined, including duration of use, hormonal constituents, dose, whether single- or two-view screening was used, or the woman's personal characteristics. Conclusion Current use of oestrogen-only and oestrogen-progestagen HRT, but not tibolone, increases the risk of false positive recall at screening. PMID:16417651

TrigDB back-filling method in EEW for the regional earthquake for reducing false location of the deep focus earthquake event by considering neighborhood triggers and forced association.

NASA Astrophysics Data System (ADS)

Park, J. H.; Chi, H. C.; Lim, I. S.; Seong, Y. J.; Pak, J.

2017-12-01

During the first phase of EEW(Earthquake Early Warning) service to the public by KMA (Korea Meteorological Administration) from 2015 in Korea, KIGAM(Korea Institute of Geoscience and Mineral Resources) has adopted ElarmS2 of UC Berkeley BSL and modified local magnitude relation, travel time curves and association procedures so called TrigDB back-filling method. The TrigDB back-filling method uses a database of sorted lists of stations based on epicentral distances of the pre-defined events located on the grids for 1,401 × 1,601 = 2,243,001 events around the Korean Peninsula at a grid spacing of 0.05 degrees. When the version of an event is updated, the TrigDB back-filling method is invoked. First, the grid closest to the epicenter of an event is chosen from the database and candidate stations, which are stations corresponding to the chosen grid and also adjacent to the already-associated stations, are selected. Second, the directions from the chosen grid to the associated stations are averaged to represent the direction of wave propagation, which is used as a reference for computing apparent travel times. The apparent travel times for the associated stations are computed using a P wave velocity of 5.5 km/s from the grid to the projected points in the reference direction. The travel times for the triggered candidate stations are also computed and used to obtain the difference between the apparent travel times of the associated stations and the triggered candidates. Finally, if the difference in the apparent travel times is less than that of the arrival times, the method forces the triggered candidate station to be associated with the event and updates the event location. This method is useful to reduce false locations of events which could be generated from the deep (> 500 km) and regional distance earthquakes happening on the subduction pacific plate boundaries. In comparison of the case study between TrigDB back-filling applied system and the others, we could get the more reliable results in the early stagy of the version updating by forced association of the neighbored stations.

False-positive cerebrospinal fluid cryptococcus antigen in Libman-Sacks endocarditis.

PubMed

Isseh, Iyad N; Bourgi, Kassem; Nakhle, Asaad; Ali, Mahmoud; Zervos, Marcus J

2016-12-01

Cryptococcus meningoencephalitis is a serious opportunistic infection associated with high morbidity and mortality in immunocompromised hosts, particularly patients with advanced AIDS disease. The diagnosis is established through cerebrospinal fluid (CSF) cryptococcus antigen detection and cultures. Cryptococcus antigen testing is usually the initial test of choice due its high sensitivity and specificity along with the quick availability of the results. We hereby report a case of a false-positive CSF cryptococcus antigen assay in a patient with systemic lupus erythematosus presenting with acute confusion. While initial CSF evaluation revealed a positive cryptococcus antigen assay, the patient's symptoms were inconsistent with cryptococcus meningoencephalitis. A repeat CSF evaluation, done 3 days later, revealed a negative CSF cryptococcus antigen assay. Given the patient's active lupus disease and the elevated antinuclear antibody titers, we believe that the initial positive result was a false positive caused by interference from autoantibodies.

Silastic injection for vocal fold medialization resulting in a false-positive finding on F18 FDG-PET/CT.

PubMed

Mahfouz, Ayman; Naji, Meeran; Mok, Wing Yan; Taghi, Ali S; Win, Zarni

2015-09-01

A false-positive uptake of F18-fluorodeoxyglucose (FDG) on positron-emission tomography/computed tomography (PET/CT) can result in confusion and misinterpretation of scans. Such uptakes have been previously described after injection of polytetrafluoroethylene (Teflon) into the vocal folds. Similarly, vocal fold injection of silicone elastomer (Silastic) can result not only in a false-positive FDG uptake on PET/CT, but also in chronic inflammation. We report a case of increased FDG uptake in a vocal fold after Silastic injection that was misinterpreted as a malignancy in a 70-year-old woman who had metastatic carcinoma of the stomach.

Apparent hyperthyroidism caused by biotin-like interference from IgM anti-streptavidin antibodies.

PubMed

Lam, Leo; Bagg, Warwick; Smith, Geoff; Chiu, Weldon; Middleditch, Martin James; Lim, Julie Ching-Hsia; Kyle, Campbell Vance

2018-05-29

Exclusion of analytical interference is important when there is discrepancy between clinical and laboratory findings. However, interferences on immunoassays are often mistaken as isolated laboratory artefacts. We characterized and report the mechanism of a rare cause of interference in two patients that caused erroneous thyroid function tests, and also affects many other biotin dependent immunoassays. Patient 1 was a 77 y female with worsening fatigue while taking carbimazole over several years. Her thyroid function tests however, were not suggestive of hypothyroidism. Patient 2 was a 25 y female also prescribed carbimazole for apparent primary hyperthyroidism. Despite an elevated FT4, the lowest TSH on record was 0.17mIU/L. In both cases, thyroid function tests performed by an alternative method were markedly different. Further characterization of both patients' serum demonstrated analytical interference on many immunoassays using the biotin-streptavidin interaction. Sandwich assays (e.g. TSH, FSH, TNT, beta-HCG) were falsely low, while competitive assays (e.g. FT4, FT3, TBII) were falsely high. Pre-incubation of serum with streptavidin microparticles removed the analytical interference, initially suggesting the cause of interference was biotin, however, neither patient had been taking biotin. Instead, a ~100kDa IgM immunoglobulin with high affinity to streptavidin was isolated from each patient's serum. The findings confirm IgM anti-streptavidin antibodies as the cause of analytical interference. We describe two patients with apparent hyperthyroidism as a result of analytical interference caused by IgM anti-streptavidin antibodies. Analytical interference identified on one immunoassay should raise the possibility of other affected results. Characterization of interference may help to identify other potentially affected immunoassays. In the case of anti-streptavidin antibodies, the pattern of interference mimics that due to biotin ingestion; however, the degree of interference varies between individual assays and between patients.

HIV misdiagnosis in sub-Saharan Africa: performance of diagnostic algorithms at six testing sites

PubMed Central

Kosack, Cara S.; Shanks, Leslie; Beelaert, Greet; Benson, Tumwesigye; Savane, Aboubacar; Ng’ang’a, Anne; Andre, Bita; Zahinda, Jean-Paul BN; Fransen, Katrien; Page, Anne-Laure

2017-01-01

Abstract Introduction: We evaluated the diagnostic accuracy of HIV testing algorithms at six programmes in five sub-Saharan African countries. Methods: In this prospective multisite diagnostic evaluation study (Conakry, Guinea; Kitgum, Uganda; Arua, Uganda; Homa Bay, Kenya; Doula, Cameroun and Baraka, Democratic Republic of Congo), samples from clients (greater than equal to five years of age) testing for HIV were collected and compared to a state-of-the-art algorithm from the AIDS reference laboratory at the Institute of Tropical Medicine, Belgium. The reference algorithm consisted of an enzyme-linked immuno-sorbent assay, a line-immunoassay, a single antigen-enzyme immunoassay and a DNA polymerase chain reaction test. Results: Between August 2011 and January 2015, over 14,000 clients were tested for HIV at 6 HIV counselling and testing sites. Of those, 2786 (median age: 30; 38.1% males) were included in the study. Sensitivity of the testing algorithms ranged from 89.5% in Arua to 100% in Douala and Conakry, while specificity ranged from 98.3% in Doula to 100% in Conakry. Overall, 24 (0.9%) clients, and as many as 8 per site (1.7%), were misdiagnosed, with 16 false-positive and 8 false-negative results. Six false-negative specimens were retested with the on-site algorithm on the same sample and were found to be positive. Conversely, 13 false-positive specimens were retested: 8 remained false-positive with the on-site algorithm. Conclusions: The performance of algorithms at several sites failed to meet expectations and thresholds set by the World Health Organization, with unacceptably high rates of false results. Alongside the careful selection of rapid diagnostic tests and the validation of algorithms, strictly observing correct procedures can reduce the risk of false results. In the meantime, to identify false-positive diagnoses at initial testing, patients should be retested upon initiating antiretroviral therapy. PMID:28691437

HIV misdiagnosis in sub-Saharan Africa: performance of diagnostic algorithms at six testing sites.

PubMed

Kosack, Cara S; Shanks, Leslie; Beelaert, Greet; Benson, Tumwesigye; Savane, Aboubacar; Ng'ang'a, Anne; Andre, Bita; Zahinda, Jean-Paul Bn; Fransen, Katrien; Page, Anne-Laure

2017-07-03

We evaluated the diagnostic accuracy of HIV testing algorithms at six programmes in five sub-Saharan African countries. In this prospective multisite diagnostic evaluation study (Conakry, Guinea; Kitgum, Uganda; Arua, Uganda; Homa Bay, Kenya; Doula, Cameroun and Baraka, Democratic Republic of Congo), samples from clients (greater than equal to five years of age) testing for HIV were collected and compared to a state-of-the-art algorithm from the AIDS reference laboratory at the Institute of Tropical Medicine, Belgium. The reference algorithm consisted of an enzyme-linked immuno-sorbent assay, a line-immunoassay, a single antigen-enzyme immunoassay and a DNA polymerase chain reaction test. Between August 2011 and January 2015, over 14,000 clients were tested for HIV at 6 HIV counselling and testing sites. Of those, 2786 (median age: 30; 38.1% males) were included in the study. Sensitivity of the testing algorithms ranged from 89.5% in Arua to 100% in Douala and Conakry, while specificity ranged from 98.3% in Doula to 100% in Conakry. Overall, 24 (0.9%) clients, and as many as 8 per site (1.7%), were misdiagnosed, with 16 false-positive and 8 false-negative results. Six false-negative specimens were retested with the on-site algorithm on the same sample and were found to be positive. Conversely, 13 false-positive specimens were retested: 8 remained false-positive with the on-site algorithm. The performance of algorithms at several sites failed to meet expectations and thresholds set by the World Health Organization, with unacceptably high rates of false results. Alongside the careful selection of rapid diagnostic tests and the validation of algorithms, strictly observing correct procedures can reduce the risk of false results. In the meantime, to identify false-positive diagnoses at initial testing, patients should be retested upon initiating antiretroviral therapy.

Safety improvement from edge lines on rural two-lane highways : tech summary.

DOT National Transportation Integrated Search

2012-01-01

The previous study "Impact of Edge Lines on Safety of Rural Two-Lane Highways" completed in 2005 concluded that, : with edge lines, centralization of a vehicle's position is more apparent during nighttime, which reduces the risk of runoff : -road (RO...

Mobile Robot Localization by Remote Viewing of a Colored Cylinder

NASA Technical Reports Server (NTRS)

Volpe, R.; Litwin, T.; Matthies, L.

1995-01-01

A system was developed for the Mars Pathfinder rover in which the rover checks its position by viewing the angle back to a colored cylinder with different colors for different angles. The rover determines distance by the apparent size of the cylinder.

Moon Illusion: An Observation.

PubMed

Goldstein, G

1962-12-21

Size comparisons of the moon are made from different locations by direct viewing (as opposed to comparisons by instrumental techniques). Under the proper conditions, the illusion is seen while the moon's position remains essentially unaltered. By this means, evidence is adduced in favor of Ptolemy's apparent-distance hypothesis.

How does negative emotion cause false memories?

PubMed

Brainerd, C J; Stein, L M; Silveira, R A; Rohenkohl, G; Reyna, V F

2008-09-01

Remembering negative events can stimulate high levels of false memory, relative to remembering neutral events. In experiments in which the emotional valence of encoded materials was manipulated with their arousal levels controlled, valence produced a continuum of memory falsification. Falsification was highest for negative materials, intermediate for neutral materials, and lowest for positive materials. Conjoint-recognition analysis produced a simple process-level explanation: As one progresses from positive to neutral to negative valence, false memory increases because (a) the perceived meaning resemblance between false and true items increases and (b) subjects are less able to use verbatim memories of true items to suppress errors.

Mechanisms and Early Detections of Multidecadal Oxygen Changes in the Interior Subpolar North Atlantic

NASA Astrophysics Data System (ADS)

Tjiputra, J. F.; Goris, N.; Lauvset, S. K.; Heinze, C.; Olsen, A.; Schwinger, J.; Steinfeldt, R.

2018-05-01

The oxygen response in the subpolar North Atlantic (SPNA) to future climate change is poorly understood. We investigate the multidecadal variability in interior oxygen and its association with the subpolar gyre index (a gyre strength proxy) for models and data. During positive phases, persistent strong Labrador Sea (LS) lateral and vertical mixing entrains oxygen-rich water into the interior southern SPNA and vice versa during negative phases. This is indicated by the observed anomalously fresh, cold, and low apparent oxygen utilization, resembling LS water mass during positive phases. We use this relationship to benchmark Earth system models. Under a high CO2 future, the best performing models project a steady decline in SPNA oxygen, driven partly by lower solubility and increases in apparent oxygen utilization. The deoxygenation depends on the sensitivity of the LS mixing to warming. The time of emergence of interior oxygen is projected to be decades earlier than that of temperature and salinity.

Differences in Viscosity of Superior and Inferior Spikelets of Japonica Rice with Various Percentages of Apparent Amylose Content.

PubMed

Ma, Zhao-Hui; Cheng, Hai-Tao; Nitta, Y; Aoki, Naohiro; Chen, Yun; Chen, Heng-Xue; Ohsugi, Ryu; Lyu, Wen-Yan

2017-05-31

Viscosity, a crucial characteristic for rice palatability, is affected by endosperm characters. We compared correlations between differences in viscosity of japonica rice with various palatability and endosperm characters. Changes in apparent amylose and protein contents (AAC% and PC%, respectively) and amylopectin side-chain distribution and the relationship of these traits with palatability were investigated in superior and inferior spikelets of good cultivars with low amylose content from Hokkaido and common cultivars from northeastern Japan, using rapid visco analyzer characteristics and rice-grain microstructures. Significant differences occurred in PC%, AAC%, breakdown, setback, peak time, and pasting temperature of different cultivars and grain positions. Amylopectin components showed remarkable differences in grain surfaces, surface layers, and section structure between the grain varieties. Hokkaido cultivars showed better viscosity than northeastern cultivars, particularly initial stage grains. Correlation analysis indicated viscosity was mainly AAC%-dependent, whereas differences in endosperm characteristics between spikelet positions were mainly due to grain-filling temperature.

Amplitude/frequency differences in a supine resting single-lead electrocardiogram of normal versus coronary heart diseased males.

DOT National Transportation Integrated Search

1974-05-01

A resting 'normal' ECG can coexist with known angina pectoris, positive angiocardiography and previous myocardial infarction. In contemporary exercise ECG tests, a false positive/false negative total error of 10% is not unusual. Research aimed at imp...

Finkelstein's test: a descriptive error that can produce a false positive.

PubMed

Elliott, B G

1992-08-01

Over the last three decades an error in performing Finkelstein's test has crept into the English literature in both text books and journals. This error can produce a false-positive, and if relied upon, a wrong diagnosis can be made, leading to inappropriate surgery.

A Demonstration of Regression False Positive Selection in Data Mining

ERIC Educational Resources Information Center

Pinder, Jonathan P.

2014-01-01

Business analytics courses, such as marketing research, data mining, forecasting, and advanced financial modeling, have substantial predictive modeling components. The predictive modeling in these courses requires students to estimate and test many linear regressions. As a result, false positive variable selection ("type I errors") is…

Comparison of the clinical and cognitive features of genetically positive ALS patients from the largest tertiary center in Serbia.

PubMed

Marjanović, Ivan V; Selak-Djokić, Biljana; Perić, Stojan; Janković, Milena; Arsenijević, Vladimir; Basta, Ivana; Lavrnić, Dragana; Stefanova, Elka; Stević, Zorica

2017-06-01

Discovering novel mutations in C9orf72, FUS, ANG, and TDP-43 genes in ALS patients arises necessities for better clinical characterizations of these subjects. The aim is to determine clinical and cognitive profile of genetically positive Serbian ALS patients. 241 ALS patients were included in the study (17 familiar and 224 apparently sporadic). The following genes were analyzed: SOD1, C9orf72, ANG, FUS, and TDP-43. An extensive battery of classic neuropsychological tests was used in 27 ALS patients (22 SOD1 positive and 5 SOD1 negative) and 82 healthy controls (HCs). Overall 37 (15.4%) of 241 ALS patients carried mutations in tested genes-among 17 familiar ALS patients 16 (94.1%) were positive and among 224 apparently sporadic 21 (9.4%) had causative mutation. Mutations in SOD1 gene were the most common, representing 27 (73.0%) of all genetically positive ALS patients. The main clinical characteristics of SOD1 positive patients were: spinal onset in lower extremities, common sphincter and sensitive disturbances, and dysexecutive syndrome. Within SOD1 positive patients, we noticed somewhat earlier onset in patients with A145G, sensory and sphincter disturbances were dominant in patients with L144F, while D90A patients had significant sensory involvement. SOD1 negative group consisted of ten (27.0%) patients (six C9orf72, two ANG, one TDP-43, and one patient baring triple FUS, C9orf72 expansion, and ANG variants). Bulbar involvement and more extensive neuropsychological impairment (including executive, visuospatial, and memory difficulties) were the main features of SOD1 negative cohort. Our results suggest that meaningful clinical suspicion of certain ALS genotype might be made based on thorough clinical evaluation of patients.

Differential specificity of selective culture media for enumeration of pathogenic vibrios: advantages and limitations of multi-plating methods.

PubMed

Nigro, Olivia D; Steward, Grieg F

2015-04-01

Plating environmental samples on vibrio-selective chromogenic media is a commonly used technique that allows one to quickly estimate concentrations of putative vibrio pathogens or to isolate them for further study. Although this approach is convenient, its usefulness depends directly on how well the procedure selects against false positives. We tested whether a chromogenic medium, CHROMagar Vibrio (CaV), used alone (single-plating) or in combination (double-plating) with a traditional medium thiosulfate-citrate-bile-salts (TCBS), could improve the discrimination among three pathogenic vibrio species (Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus) and thereby decrease the number of false-positive colonies that must be screened by molecular methods. Assays were conducted on water samples from two estuarine environments (one subtropical, one tropical) in a variety of seasonal conditions. The results of the double-plating method were confirmed by PCR and 16S rRNA sequencing. Our data indicate that there is no significant difference in the false-positive rate between CaV and TCBS when using a single-plating technique, but determining color changes on the two media sequentially (double-plating) reduced the rate of false positive identification in most cases. The improvement achieved was about two-fold on average, but varied greatly (from 0- to 5-fold) and depended on the sampling time and location. The double-plating method was most effective for V. vulnificus in warm months, when overall V. vulnificus abundance is high (false positive rates as low as 2%, n=178). Similar results were obtained for V. cholerae (minimum false positive rate of 16%, n=146). In contrast, the false positive rate for V. parahaemolyticus was always high (minimum of 59%, n=109). Sequence analysis of false-positive isolates indicated that the majority of confounding isolates are from the Vibrionaceae family, however, members of distantly related bacterial groups were also able to grow on vibrio-selective media, even when using the double-plating method. In conclusion, the double-plating assay is a simple means to increase the efficiency of identifying pathogenic vibrios in aquatic environments and to reduce the number of molecular assays required for identity confirmation. However, the high spatial and temporal variability in the performance of the media mean that molecular approaches are still essential to obtain the most accurate vibrio abundance estimates from environmental samples. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of mood on false memory for emotional DRM word lists.

PubMed

Zhang, Weiwei; Gross, Julien; Hayne, Harlene

2017-04-01

In the present study, we investigated the effect of participants' mood on true and false memories of emotional word lists in the Deese-Roediger-McDermott (DRM) paradigm. In Experiment 1, we constructed DRM word lists in which all the studied words and corresponding critical lures reflected a specified emotional valence. In Experiment 2, we used these lists to assess mood-congruent true and false memory. Participants were randomly assigned to one of three induced-mood conditions (positive, negative, or neutral) and were presented with word lists comprised of positive, negative, or neutral words. For both true and false memory, there was a mood-congruent effect in the negative mood condition; this effect was due to a decrease in true and false recognition of the positive and neutral words. These findings are consistent with both spreading-activation and fuzzy-trace theories of DRM performance and have practical implications for our understanding of the effect of mood on memory.

Use of the false discovery rate for evaluating clinical safety data.

PubMed

Mehrotra, Devan V; Heyse, Joseph F

2004-06-01

Clinical adverse experience (AE) data are routinely evaluated using between group P values for every AE encountered within each of several body systems. If the P values are reported and interpreted without multiplicity considerations, there is a potential for an excess of false positive findings. Procedures based on confidence interval estimates of treatment effects have the same potential for false positive findings as P value methods. Excess false positive findings can needlessly complicate the safety profile of a safe drug or vaccine. Accordingly, we propose a novel method for addressing multiplicity in the evaluation of adverse experience data arising in clinical trial settings. The method involves a two-step application of adjusted P values based on the Benjamini and Hochberg false discovery rate (FDR). Data from three moderate to large vaccine trials are used to illustrate our proposed 'Double FDR' approach, and to reinforce the potential impact of failing to account for multiplicity. This work was in collaboration with the late Professor John W. Tukey who coined the term 'Double FDR'.

Are false-positive rates leading to an overestimation of noise-induced hearing loss?

PubMed

Schlauch, Robert S; Carney, Edward

2011-04-01

To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms. Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center for Health Statistics, 1994) were examined using published rules for identifying noise notches at various pass-fail criteria. These results were compared with computer-simulated "flat" audiograms. The proportion of these identified as having a noise notch is an estimate of the false-positive rate for a particular rule. Audiograms from the NHANES III for children 6-11 years of age yielded notched audiograms at rates consistent with simulations, suggesting that this group does not have significant NIHL. Further, pass-fail criteria for rules suggested by expert clinicians, applied to NHANES III audiometric data, yielded unacceptably high false-positive rates. Computer simulations provide an effective method for estimating false-positive rates for protocols used to identify notched audiograms. Audiometric precision could possibly be improved by (a) eliminating systematic calibration errors, including a possible problem with reference levels for TDH-style earphones; (b) repeating and averaging threshold measurements; and (c) using earphones that yield lower variability for 6.0 and 8.0 kHz--2 frequencies critical for identifying noise notches.

False-positive cancer screens and health-related quality of life.

PubMed

McGovern, Patricia M; Gross, Cynthia R; Krueger, Richard A; Engelhard, Deborah A; Cordes, Jill E; Church, Timothy R

2004-01-01

By design, screening tests are imperfect-unresponsive to some cancers (false negatives) while occasionally raising suspicion of cancer where none exists (false positives). This pilot study describes patients' responses to having a false-positive screening test for cancer, and identifies screening effects on health-related quality of life (HRQoL). The pilot findings suggest issues important for incorporation in future evaluations of the impact of screening for prostate, lung, colon, or ovarian (PLCO) cancers. Seven focus groups were conducted to identify the nature and meaning of all phases of PLCO screening. Minnesota participants in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial who had completed screening, with at least 1 false-positive screen, participated (N = 47). Participants' reactions to abnormal screens and diagnostic work-ups were primarily emotional (eg, anxiety and distress), not physical, and ultimately positive for the majority. Health distress and fear of cancer and death were the major negative aspects of HRQoL identified. These concepts are not typically included in generic HRQoL questionnaires like the SF-36, but are highly relevant to PLCO screening. Clinicians were regarded as underestimating the discomfort of follow-up diagnostic testing. However, relief and assurance appeared to eventually outweigh the negative emotions for most participants. Implications for oncology nurses include the need to consider the emotional consequences of screening in association with screen reliability and validity.

Comparison of scanty AFB smears against culture in an area with high HIV prevalence.

PubMed

Lawson, L; Yassin, M A; Ramsay, A; Emenyonu, N E; Squire, S B; Cuevas, L E

2005-08-01

To verify among tuberculosis (TB) suspects attending hospitals in Abuja, Nigeria, if sputum smears graded as scanty are false-positive, sputum smears from 1068 patients were graded with the International Union Against Tuberculosis and Lung Disease classification. One specimen was cultured. Eight hundred and twenty-four (26%) smears were positive, 137 (4%) scanty and 2243 negative. Of 1068 cultures, 680 (64%) were positive. One hundred and thirty (95%) scanty and 809 (98%) positive smears were culture-positive. Twelve of 18 patients with a single scanty smear and 51 of 52 with > or = 2 scanty smears were culture-positive. Fewer than < 5% scanty results, < 1% of the patients treated for TB, are false-positive.

Cross-reactivity between Lyme and syphilis screening assays: Lyme disease does not cause false-positive syphilis screens.

PubMed

Patriquin, Glenn; LeBlanc, Jason; Heinstein, Charles; Roberts, Catherine; Lindsay, Robbin; Hatchette, Todd F

2016-03-01

Increased rates of Lyme disease and syphilis in the same geographic area prompted an assessment of screening test cross-reactivity. This study supports the previously described cross-reactivity of Lyme screening among syphilis-positive sera and reports evidence against the possibility of false-positive syphilis screening tests resulting from previous Borrelia burgdorferi infection. Copyright © 2016 Elsevier Inc. All rights reserved.

The incidence and clinical implication of sputum with positive acid-fast bacilli smear but negative in mycobacterial culture in a tertiary referral hospital in South Korea.

PubMed

Lee, Jae Seok; Kim, Eui-Chong; Joo, Sei Ick; Lee, Sang-Min; Yoo, Chul-Gyu; Kim, Young Whan; Han, Sung Koo; Shim, Young-Soo; Yim, Jae-Joon

2008-10-01

Although it is not rare to find sputum that is positive acid-fast bacilli (AFB) smear but subsequent culture fails to isolate mycobacteria in clinical practice, the incidence and clinical implication of those sputa from new patients has not been clearly elucidated. The aim of this study was to determine the incidence and clinical implication of sputum with positive AFB smear but negative in mycobacterial culture. All sputa that were positive AFB smear requested during diagnostic work up for new patients visiting Seoul National University Hospital from 1 January 2005 through 31 December 2006 were included. Sputa producing a positive AFB smear but negative mycobacterial culture were classified into one of four categories: laboratory failure to isolate mycobacteria, false positive AFB smear, pathogen may show a positive AFB smear other than mycobacteria, and indeterminate results. Out of 447 sputa with a positive AFB smear, 29 (6.5%) failed to culture any organism. Among these 29 sputa, 18 were caused by laboratory failure to isolate mycobacteria, six were false positive smears, and five indeterminate. Although most sputum with a positive AFB smear but negative culture could be classified as a laboratory failure, clinicians should consider the possibility of false positive AFB smear.

Potential for false positive HIV test results with the serial rapid HIV testing algorithm.

PubMed

Baveewo, Steven; Kamya, Moses R; Mayanja-Kizza, Harriet; Fatch, Robin; Bangsberg, David R; Coates, Thomas; Hahn, Judith A; Wanyenze, Rhoda K

2012-03-19

Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold). However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2%) were HIV negative. Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals.

Potential for false positive HIV test results with the serial rapid HIV testing algorithm

PubMed Central

2012-01-01

Background Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Results Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold). However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2%) were HIV negative. Conclusion Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals. PMID:22429706

A new Late Cretaceous paleomagnetic pole from the Adel Mountains, west central Montana

NASA Astrophysics Data System (ADS)

Gunderson, Jay A.; Sheriff, Steven D.

1991-01-01

North America's apparent polar wander path has been poorly defined between the mid-Cretaceous and Paleocene reference pole positions. Existing data allowed 13° of apparent polar motion over about 22 m.y. (87-65 Ma) roughly coinciding with the beginning of Laramide deformation (˜80 Ma). We report on a paleomagnetic study of the Adel Mountain Volcanic rocks to refine the North American apparent polar wander path for this interval. The shonkinite rocks of the Adel Mountain Volcanic field are on the eastern edge of the Cretaceous-Paleocene fold and thrust belt; some of these structures disturb the western edge of the volcanic pile. We obtained two new K-Ar dates from the Adel rocks. One date, on biotite ( from a shonkinite dike that crosscuts most of the volcanic rocks, is 71.2±2.7 Ma. The other, a whole rock date from a flow deep in the volcanic pile, is 81.1±3.5 Ma. We collected six to nine paleomagnetic samples from each of 34 sites in roadcuts and natural outcrops of flows, dikes, and laccoliths. Positive fold and conglomerate tests, along with alternating field and thermal demagnetization, indicate that our characteristic remanent directions are primary magnetizations acquired before Late Cretaceous to Paleocene thrust belt deformation. Averaging the virtual geomagnetic poles from 26 reliable sites, all of normal polarity, yields a paleopole at 82.2°N, 209.9°E (α95 = 6.80°, k = 18.38). This pole is concordant with the Paleocene reference pole (82.0°N, 170.2°E, α95 = 3.5°, k = 18.6 (Diehl et al., 1983)) and is 11.6° from the Globerman and Irving (1988) mid-Cretaceous pole at 71°N, 196°E. The youngest information in the Cretaceous stillstand pole is from the Niobrara Formation (Shive and Frerichs, 1974) at about 85-89 Ma. If we take the average age of the Adel Mountain Volcanics to be 76 Ma, then ˜12° of apparent polar motion occurred between 87 Ma and 76 Ma. Thus, rapid apparent polar motion correlates well with the onset of Laramide deformation.

Prediction-Oriented Marker Selection (PROMISE): With Application to High-Dimensional Regression.

PubMed

Kim, Soyeon; Baladandayuthapani, Veerabhadran; Lee, J Jack

2017-06-01

In personalized medicine, biomarkers are used to select therapies with the highest likelihood of success based on an individual patient's biomarker/genomic profile. Two goals are to choose important biomarkers that accurately predict treatment outcomes and to cull unimportant biomarkers to reduce the cost of biological and clinical verifications. These goals are challenging due to the high dimensionality of genomic data. Variable selection methods based on penalized regression (e.g., the lasso and elastic net) have yielded promising results. However, selecting the right amount of penalization is critical to simultaneously achieving these two goals. Standard approaches based on cross-validation (CV) typically provide high prediction accuracy with high true positive rates but at the cost of too many false positives. Alternatively, stability selection (SS) controls the number of false positives, but at the cost of yielding too few true positives. To circumvent these issues, we propose prediction-oriented marker selection (PROMISE), which combines SS with CV to conflate the advantages of both methods. Our application of PROMISE with the lasso and elastic net in data analysis shows that, compared to CV, PROMISE produces sparse solutions, few false positives, and small type I + type II error, and maintains good prediction accuracy, with a marginal decrease in the true positive rates. Compared to SS, PROMISE offers better prediction accuracy and true positive rates. In summary, PROMISE can be applied in many fields to select regularization parameters when the goals are to minimize false positives and maximize prediction accuracy.

False positive computed tomographic angiography for Stanford type A aortic dissection.

PubMed

Bandali, Murad F; Hatem, Muhammed A; Appoo, Jehangir J; Hutchison, Stuart J; Wong, Jason K

2015-12-01

Computed tomographic angiography (CTA) has emerged as the defacto imaging test to rule out acute aortic dissection; however, it is not without flaws. We report a case of a false-positive CTA with respect to Stanford Type A aortic dissection. A 52 year-old male presented with sudden onset shortness of breath. He denied chest pain. Due to severe hypertension and an Emergency Department bedside ultrasound suggesting an intimal flap in the aorta, CTA was requested to better assess the ascending aorta and was interpreted as consistent with Stanford Type A aortic dissection with thrombosis of the false lumen in the ascending aorta. However, intra-operative imaging (TEE and epi-aortic scanning) did not identify an intimal flap or dissection, and neither did definitive surgical inspection of the aorta. The suspected aortic dissection and thrombosed false lumen were not visualized on repeat CTA two days later. False positive diagnosis of Stanford Type A aortic dissection on CTA can be the result of technical factors, streak artifacts, motion artifacts, and periaortic structures. In this case, non-uniform arterial contrast enhancement secondary to unrecognized biventricular dysfunction resulted in the false positive CTA appearance of an intimal flap and mural thrombus. Intra-operative TEE and epi-aortic scanning were proven correct in excluding aortic dissection by the standard of definitive surgical inspection of the aorta.

Evaluation of HIV testing algorithms in Ethiopia: the role of the tie-breaker algorithm and weakly reacting test lines in contributing to a high rate of false positive HIV diagnoses.

PubMed

Shanks, Leslie; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Pirou, Erwan; Ritmeijer, Koert; Masiga, Johnson; Abebe, Almaz

2015-02-03

In Ethiopia a tiebreaker algorithm using 3 rapid diagnostic tests (RDTs) in series is used to diagnose HIV. Discordant results between the first 2 RDTs are resolved by a third 'tiebreaker' RDT. Médecins Sans Frontières uses an alternate serial algorithm of 2 RDTs followed by a confirmation test for all double positive RDT results. The primary objective was to compare the performance of the tiebreaker algorithm with a serial algorithm, and to evaluate the addition of a confirmation test to both algorithms. A secondary objective looked at the positive predictive value (PPV) of weakly reactive test lines. The study was conducted in two HIV testing sites in Ethiopia. Study participants were recruited sequentially until 200 positive samples were reached. Each sample was re-tested in the laboratory on the 3 RDTs and on a simple to use confirmation test, the Orgenics Immunocomb Combfirm® (OIC). The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. 2620 subjects were included with a HIV prevalence of 7.7%. Each of the 3 RDTs had an individual specificity of at least 99%. The serial algorithm with 2 RDTs had a single false positive result (1 out of 204) to give a PPV of 99.5% (95% CI 97.3%-100%). The tiebreaker algorithm resulted in 16 false positive results (PPV 92.7%, 95% CI: 88.4%-95.8%). Adding the OIC confirmation test to either algorithm eliminated the false positives. All the false positives had at least one weakly reactive test line in the algorithm. The PPV of weakly reacting RDTs was significantly lower than those with strongly positive test lines. The risk of false positive HIV diagnosis in a tiebreaker algorithm is significant. We recommend abandoning the tie-breaker algorithm in favour of WHO recommended serial or parallel algorithms, interpreting weakly reactive test lines as indeterminate results requiring further testing except in the setting of blood transfusion, and most importantly, adding a confirmation test to the RDT algorithm. It is now time to focus research efforts on how best to translate this knowledge into practice at the field level. Clinical Trial registration #: NCT01716299.

The use of equine surfactant and positive pressure ventilation to treat a premature alpaca cria with severe hypoventilation and hypercapnia

PubMed Central

Tinkler, Stacy H.; Mathews, Lindsey A.; Firshman, Anna M.; Quandt, Jane E.

2015-01-01

A 5-hour-old, premature alpaca cria was presented with failure to nurse, weakness, hypoglycemia, hypercapnia, and respiratory distress. The cria was treated with 3 doses of fresh, crude equine surfactant, positive pressure ventilation, and supplemental intranasal oxygen. Recovery to discharge was uneventful, and the cria regained apparently normal respiratory function. Three years after hospital discharge, the alpaca was a healthy adult. PMID:25829556

Looking into the water with oblique head tilting: revision of the aerial binocular imaging of underwater objects.

PubMed

Horváth, Gábor; Buchta, Krisztián; Varjú, Dezsö

2003-06-01

It is a well-known phenomenon that when we look into the water with two aerial eyes, both the apparent position and the apparent shape of underwater objects are different from the real ones because of refraction at the water surface. Earlier studies of the refraction-distorted structure of the underwater binocular visual field of aerial observers were restricted to either vertically or horizontally oriented eyes. We investigate a generalized version of this problem: We calculate the position of the binocular image point of an underwater object point viewed by two arbitrarily positioned aerial eyes, including oblique orientations of the eyes relative to the flat water surface. Assuming that binocular image fusion is performed by appropriate vergent eye movements to bring the object's image onto the foveas, the structure of the underwater binocular visual field is computed and visualized in different ways as a function of the relative positions of the eyes. We show that a revision of certain earlier treatments of the aerial imaging of underwater objects is necessary. We analyze and correct some widespread erroneous or incomplete representations of this classical geometric optical problem that occur in different textbooks. Improving the theory of aerial binocular imaging of underwater objects, we demonstrate that the structure of the underwater binocular visual field of aerial observers distorted by refraction is more complex than has been thought previously.

Applying a CAD-generated imaging marker to assess short-term breast cancer risk

NASA Astrophysics Data System (ADS)

Mirniaharikandehei, Seyedehnafiseh; Zarafshani, Ali; Heidari, Morteza; Wang, Yunzhi; Aghaei, Faranak; Zheng, Bin

2018-02-01

Although whether using computer-aided detection (CAD) helps improve radiologists' performance in reading and interpreting mammograms is controversy due to higher false-positive detection rates, objective of this study is to investigate and test a new hypothesis that CAD-generated false-positives, in particular, the bilateral summation of false-positives, is a potential imaging marker associated with short-term breast cancer risk. An image dataset involving negative screening mammograms acquired from 1,044 women was retrospectively assembled. Each case involves 4 images of craniocaudal (CC) and mediolateral oblique (MLO) view of the left and right breasts. In the next subsequent mammography screening, 402 cases were positive for cancer detected and 642 remained negative. A CAD scheme was applied to process all "prior" negative mammograms. Some features from CAD scheme were extracted, which include detection seeds, the total number of false-positive regions, an average of detection scores and the sum of detection scores in CC and MLO view images. Then the features computed from two bilateral images of left and right breasts from either CC or MLO view were combined. In order to predict the likelihood of each testing case being positive in the next subsequent screening, two logistic regression models were trained and tested using a leave-one-case-out based cross-validation method. Data analysis demonstrated the maximum prediction accuracy with an area under a ROC curve of AUC=0.65+/-0.017 and the maximum adjusted odds ratio of 4.49 with a 95% confidence interval of [2.95, 6.83]. The results also illustrated an increasing trend in the adjusted odds ratio and risk prediction scores (p<0.01). Thus, the study showed that CAD-generated false-positives might provide a new quantitative imaging marker to help assess short-term breast cancer risk.

Looking for Childhood Schizophrenia: Case Series of False Positives.

ERIC Educational Resources Information Center

Stayer, Catherine; Sporn, Alexandra; Gogtay, Nitin; Tossell, Julia; Lenane, Marge; Gochman, Peter; Rapoport, Judith L.

2004-01-01

Extensive experience with the diagnosis of childhood-onset schizophrenia indicates a high rate of false positives. Most mislabeled patients have chronic disabling, affective, or behavioral disorders. The authors report the cases of three children who passed stringent initial childhood-onset schizophrenia "screens" but had no chronic psychotic…

[Evaluation of performance and false positivity of Mediace RPR test that uses a chemistry autoanalyzer].

PubMed

Noh, Jaekwang; Ko, Hak Hyun; Yun, Yeomin; Choi, Young Sook; Lee, Sang Gon; Shin, Sue; Han, Kyou Sup; Song, Eun Young

2008-08-01

We evaluated the performance and false positive rate of Mediace RPR test (Sekisui, Japan), a newly introduced nontreponemal test using a chemistry autoanalyzer. The sensitivity of Mediace RPR test was analyzed using sera from 50 patients with syphilis in different stages (8 primary, 7 secondary, and 35 latent), 14 sera positive with fluorescent treponemal antibody absorption (FTA-ABS) IgM, and 74 sera positive with conventional rapid plasma regain (RPR) card test (Asan, Korea) and also positive with Treponema pallidum hemagglutination (TPHA) test or FTA-ABS IgG test. The specificity was analyzed on 108 healthy blood donors. We also performed RPR card test on 302 sera that had been tested positive with Mediace RPR test and also performed TPHA or FTA-ABS IgG test to analyze the false positive rate of Mediace RPR test. A cutoff value of 0.5 R.U. (RPR unit) was used for Mediace RPR test. Mediace RPR test on syphilitic sera of different stages (primary, secondary, and latent stages) and FTA-ABS IgM positive sera showed a sensitivity of 100%, 100%, 82.9% and 100%, respectively. Among the 74 sera positive with conventional RPR card test and TPHA or FTA-ABS IgG test, 55 were positive with Mediace test. The specificity of Mediace RPR test on blood donors was 97.2%. Among the 302 sera positive with Mediace RPR test, 137 sera (45.4%) were negative by RPR card and TPHA/FTA-ABS IgG tests. Although the sensitivities of Mediace RPR were good for primary and secondary syphilis, due to its high negative rate of Mediace RPR over the conventional RPR positive samples, further studies are necessary whether it can replace conventional nontreponemal test for screening purpose. Moreover, in view of the high false positive rate, positive results by Mediace RPR test should be confirmed with treponemal tests.

Crafting Research from the Liminal Space

ERIC Educational Resources Information Center

Burns, Stuart

2012-01-01

Tony Watson developed an approach of "intellectual craftsmanship" within management research and writing, and appealed for the hand behind the text to be made visible. This paper considers the tensions apparent between the utility of writing and the positionality of the researcher. I explore the tensions, limitations and formational…

Bridging Geography and Education for Sustainable Development: A Korean Example

ERIC Educational Resources Information Center

Gress, Douglas R.; Tschapka, Johannes M.

2017-01-01

There is an apparent disconnect between geography and education for sustainable development (ESD), with geography underrepresented in publications and curricula related to sustainability though the discipline embraces the need to foment positive change. To bridge this schism, this article introduces advances in education for sustainable…

A spreadsheet that calculates meteor orbits

NASA Astrophysics Data System (ADS)

Langbroek, M.

2004-08-01

The author has written an MS Excel spreadsheet application called Metorb08.xls which calculates a meteor's orbital elements from its apparent radiant position and initial speed. It can be downloaded from URL http://home.wanadoo.nl/marco.langbroek along with a suite of other meteor-related Excel applications.

Old Age and Literature: An Overview

ERIC Educational Resources Information Center

Ansello, Edward F.

1977-01-01

Analysis of old age and literature provides some support for the position that cultural stereotypes regarding growing older, biases with considerable history, continue to be reflected in the printed word. It seems most apparent that earlier developmental stages--historically and chronologically--are more subject to constricted representations of…

The news on smoking: newspaper coverage of smoking and health in Australia, 1987-88.

PubMed Central

Chapman, S

1989-01-01

All newspaper articles (n = 1601) mentioning tobacco or smoking drawn from a 12-month census of 30 Australian capital city newspapers in 1987-88 were coded for content, "slant," and apparent origin. Overall, 62 percent of articles were positive in their orientation toward smoking control objectives, 17 percent were negative, and 21 percent were neutral. Newspapers owned by Rupert Murdoch published 55.7 percent positive and 23.7 percent negative articles compared to 68.0 percent positive and 13.7 percent negative articles in the other large chain of Australian newspapers. PMID:2782518

The Diagnostic Validity of the 13C-Urea Breath Test in the Gastrectomized Patients: Single Tertiary Center Retrospective Cohort Study

PubMed Central

Kwon, Yong Hwan; Kim, Nayoung; Lee, Ju Yup; Choi, Yoon Jin; Yoon, Kichul; Yoon, Hyuk; Shin, Cheol Min; Park, Young Soo; Lee, Dong Ho

2014-01-01

Background: This study was conducted to evaluate the diagnostic validity of the 13C-urea breath test (13C-UBT) in the remnant stomach after partial gastrectomy for gastric cancer. Methods: The 13C-UBT results after Helicobacter pylori eradication therapy was compared with the results of endoscopic biopsy-based methods in the patients who have received partial gastrectomy for the gastric cancer. Results: Among the gastrectomized patients who showed the positive 13C-UBT results (≥ 2.5‰, n = 47) and negative 13C-UBT results (< 2.5‰, n = 114) after H. pylori eradication, 26 patients (16.1%) and 4 patients (2.5%) were found to show false positive and false negative results based on biopsy-based methods, respectively. The sensitivity, specificity, false positive rate, and false negative rate for the cut-off value of 2.5‰ were 84.0%, 80.9%, 19.1%, and 16.0%, respectively. The positive and negative predictive values were 44.7% and 96.5%, respectively. In the multivariate analysis, two or more H. pylori eradication therapies (odds ratio = 3.248, 95% confidence interval= 1.088–9.695, P = 0.035) was associated with a false positive result of the 13C-UBT. Conclusions: After partial gastrectomy, a discordant result was shown in the positive 13C-UBT results compared to the endoscopic biopsy methods for confirming the H. pylori status after eradication. Additional endoscopic biopsy-based H. pylori tests would be helpful to avoid unnecessary treatment for H. pylori eradication in these cases. PMID:25574466

Mental Rotation in False Belief Understanding.

PubMed

Xie, Jiushu; Cheung, Him; Shen, Manqiong; Wang, Ruiming

2018-05-01

This study examines the spontaneous use of embodied egocentric transformation (EET) in understanding false beliefs in the minds of others. EET involves the participants mentally transforming or rotating themselves into the orientation of an agent when trying to adopt his or her visuospatial perspective. We argue that psychological perspective taking such as false belief reasoning may also involve EET because of what has been widely reported in the embodied cognition literature, showing that our processing of abstract, propositional information is often grounded in concrete bodily sensations which are not apparently linked to higher cognition. In Experiment 1, an agent placed a ball into one of two boxes and left. The ball then rolled out and moved either into the other box (new box) or back into the original one (old box). The participants were to decide from which box they themselves or the agent would try to recover the ball. Results showed that false belief performance was affected by increased orientation disparity between the participants and the agent, suggesting involvement of embodied transformation. In Experiment 2, false belief was similarly induced and the participants were to decide if the agent would try to recover the ball in one specific box. Orientation disparity was again found to affect false belief performance. The present results extend previous findings on EET in visuospatial perspective taking and suggest that false belief reasoning, which is a kind of psychological perspective taking, can also involve embodied rotation, consistent with the embodied cognition view. Copyright © 2018 Cognitive Science Society, Inc.

Development and Implementation of Metrics for Identifying Military Impulse Noise

DTIC Science & Technology

2010-09-01

False Negative Rate FP False Positive FPR False Positive Rate FtC Fort Carson, CO GIS Geographic Information System GMM Gaussian mixture model Hz...60 70 80 90 100 110 Bin Number B in N um be r N um ber of D ata Points M apped to B in 14 Figure 8. Plot of typical neuron activation...signal metrics and waveform itself were saved and transmitted to the home base. There is also a provision to download the entire recorded waveform

Whole-body scintigraphy with radioiodine-131. A comprehensive list of false-positives with some examples.

PubMed

McDougall, I R

1995-10-01

Whole-body scintigraphy with radioiodine-131 is an important diagnostic test in the management of patients with differentiated thyroid cancer who have undergone surgical treatment. The scan can demonstrate the presence of residual thyroid or functioning metastases in lymph nodes or distant sites. However, there are a number of potential pitfalls in the interpretation of this scan that could lead to a false-positive diagnosis of cancer. The scintiscans are presented for five patients in whom uptake outside of the thyroid was not due to functioning metastases. Some of these abnormalities are physiologic, such as uptake of iodine in the gastrointestinal tract. A comprehensive list of false-positive results are tabulated.

Two cases of false-positive dengue non-structural protein 1 (NS1) antigen in patients with hematological malignancies and a review of the literature on the use of NS1 for the detection of Dengue infection.

PubMed

Chung, Shimin J; Krishnan, Prabha U; Leo, Yee Sin

2015-02-01

Early diagnosis of dengue has been made easier in recent years owing to the advancement in diagnostic technologies. The rapid non-structural protein 1 (NS1) test strip is widely used in many developed and developing regions at risk of dengue. Despite the relatively high specificity of this test, we recently encountered two cases of false-positive dengue NS1 antigen in patients with underlying hematological malignancies. We reviewed the literature for causes of false-positive dengue NS1. © The American Society of Tropical Medicine and Hygiene.

Rapid automated method for screening of enteric pathogens from stool specimens.

PubMed Central

Villasante, P A; Agulla, A; Merino, F J; Pérez, T; Ladrón de Guevara, C; Velasco, A C

1987-01-01

A total of 800 colonies suggestive of Salmonella, Shigella, or Yersinia species isolated on stool differential agar media were inoculated onto both conventional biochemical test media (triple sugar iron agar, urea agar, and phenylalanine agar) and Entero Pathogen Screen cards of the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.). Based on the conventional tests, the AutoMicrobic system method yielded the following results: 587 true-negatives, 185 true-positives, 2 false-negatives, and 26 false-positives (sensitivity, 99%; specificity, 96%). Both true-positive and true-negative results were achieved considerably earlier than false results (P less than 0.001). The Entero Pathogen Screen card method is a fast, easy, and sensitive method for screening for Salmonella, Shigella, or Yersinia species. The impossibility of screening for oxidase-positive pathogens is a minor disadvantage of this method. PMID:3553230

On the systematics in apparent proper motions of radio sources observed by VLBI

NASA Astrophysics Data System (ADS)

Raposo-Pulido, V.; Lambert, S.; Capitaine, N.; Nilsson, T.; Heinkelmann, R.; Schuh, H.

2015-08-01

For about twenty years, several authors have been investigating the systematics in the apparent proper motions of radio source positions. In some cases, the theoretical work developed (Pyne et al., 1996) could not be assessed due to the few number of VLBI observations. In other cases, the effects attributed to apparent proper motion could not be related successfully because there were no significant evidences from a statistical point of view (MacMillan, 2005). In this work we provide considerations about the estimation of the coefficients of spherical harmonics, based on a three-step procedure used by Titov et al. (2011) and Titov and Lambert (2013). The early stage of this work has been to compare step by step the computations and estimation processes between the Calc/Solve (http://gemini.gsfc.nasa.gov/solve/) and VieVS software (Böhm et al., 2012). To achieve this, the results were analyzed and compared with the previous study done by Titov and Lambert (2013).

Determination of apparent quantum yield spectra of DMS photo-degradation in an in situ iron-induced Northeast Pacific Ocean bloom

NASA Astrophysics Data System (ADS)

Bouillon, René-Christian; Miller, William L.

2004-03-01

The wavelength dependence of the photochemical removal efficiency for DMS was studied for samples from an iron-induced bloom in the Northeastern Pacific Ocean. In July 2002, a 64 km2 patch of ocean was iron-fertilized near Ocean Station Papa (50°12'N 144°45'W). Only small changes in pseudo-first-order apparent quantum yield (AQY*DMS(λ)) were observed outside the iron-patch. However, inside the patch, AQY*DMS(λ) decreased considerably over the two weeks following the initial iron injection. A positive strong correlation was found between pseudo-first-order apparent quantum yield determined at 330 nm (AQY*DMS(330 nm)) and NO3- concentrations. We propose that NO3--photolysis has a substantial influence on DMS photo-degradation rates in oceanic waters. This finding demonstrates that in addition to control DMS production, marine phytoplankton could indirectly influence the DMS photochemical loss rate via its control on NO3- distribution.

Influence of external factors on the self-assembly of two structurally related antidepressant drugs: a thermodynamic study

NASA Astrophysics Data System (ADS)

Gutiérrez-Pichel, Manuel; Attwood, David; Taboada, Pablo; Mosquera, Víctor

Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic antidepressant drugs imipramine and desipramine hydrochlorides have been determined from density and ultrasound velocity measurements in the temperature range 288.15-313.15 K in buffered solution of pH 3.0 and 5.5. Critical concentrations for aggregation of these drugs were obtained from inflections on the plots of the sound velocity against drug concentration. Positive deviation from the Debye-Hückel limiting law of the apparent molal volume of imipramine provides evidence of limited association at concentrations below the critical concentration over the temperature range studied. Apparent molal adiabatic compressibilities of the aggregates formed by the drugs, calculated by combining the ultrasound velocity and density data, were typical of those for a stacked aggregate. The critical concentration and energy involved in the aggregation process of these drugs have been evaluated using isothermal titration calorimetry. The solvent-aggregate interactions have been discussed from compressibility and calorimetry data.

Risk management and precaution: insights on the cautious use of evidence.

PubMed Central

Hrudey, Steve E; Leiss, William

2003-01-01

Risk management, done well, should be inherently precautionary. Adopting an appropriate degree of precaution with respect to feared health and environmental hazards is fundamental to risk management. The real problem is in deciding how precautionary to be in the face of inevitable uncertainties, demanding that we understand the equally inevitable false positives and false negatives from screening evidence. We consider a framework for detection and judgment of evidence of well-characterized hazards, using the concepts of sensitivity, specificity, positive predictive value, and negative predictive value that are well established for medical diagnosis. Our confidence in predicting the likelihood of a true danger inevitably will be poor for rare hazards because of the predominance of false positives; failing to detect a true danger is less likely because false negatives must be rarer than the danger itself. Because most controversial environmental hazards arise infrequently, this truth poses a dilemma for risk management. PMID:14527835

Emotion and false memory: How goal-irrelevance can be relevant for what people remember.

PubMed

Van Damme, Ilse; Kaplan, Robin L; Levine, Linda J; Loftus, Elizabeth F

2017-02-01

Elaborating on misleading information concerning emotional events can lead people to form false memories. The present experiment compared participants' susceptibility to false memories when they elaborated on information associated with positive versus negative emotion and pregoal versus postgoal emotion. Pregoal emotion reflects appraisals that goal attainment or failure is anticipated but has not yet occurred (e.g., hope and fear). Postgoal emotion reflects appraisals that goal attainment or failure has already occurred (e.g., happiness and devastation). Participants watched a slideshow depicting an interaction between a couple and were asked to empathise with the protagonist's feelings of hope (positive pregoal), happiness (positive postgoal), fear (negative pregoal), or devastation (negative postgoal); in control conditions, no emotion was mentioned. Participants were then asked to reflect on details of the interaction that had occurred (true) or had not occurred (false), and that were relevant or irrelevant to the protagonist's goal. Irrespective of emotional valence, participants in the pregoal conditions were more susceptible to false memories concerning goal-irrelevant details than were participants in the other conditions. These findings support the view that pregoal emotions narrow attention to information relevant to goal pursuit, increasing susceptibility to false memories for irrelevant information.

Predicting the carcinogenicity of chemicals with alternative approaches: recent advances.

PubMed

Benigni, Romualdo

2014-09-01

Alternative approaches to the rodent bioassay are necessary for early identification of problematic drugs and biocides during the development process, and are the only practicable tool for assessing environmental chemicals with no or adequate safety documentation. This review informs on: i) the traditional prescreening through genotoxicity testing; ii) an integrative approach that assesses DNA-reactivity and ability to disorganize tissues; iii) new applications of omics technologies (ToxCast/Tox21 project); iv) a pragmatic approach aimed at filling data gaps by intrapolating/extrapolating from similar chemicals (read-across, category formation). The review also approaches the issue of the concerns about false-positive and false-negative results that prevents a wider acceptance and use of alternatives. The review addresses strengths and limitations of various proposals, and concludes on the need of differential approaches to the issue of false negatives and false positives. False negatives can be eliminated or reduced below the variability of the animal assay with conservative quantitative structure-activity relationships or in vitro tests; false positives can be cleared with ad hoc mechanistically based follow-ups. This framework can permit a reduction of animal testing and a better protection of human health.

A CAUTIONARY TALE: MARVELS BROWN DWARF CANDIDATE REVEALS ITSELF TO BE A VERY LONG PERIOD, HIGHLY ECCENTRIC SPECTROSCOPIC STELLAR BINARY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mack, Claude E. III; Stassun, Keivan G.; De Lee, Nathan

2013-05-15

We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R {approx}< 30, 000), this particular stellar binary mimics a single-lined binary with an RV signal that would be induced by a brown dwarf companion (Msin i {approx} 50 M{sub Jup}) to a solar-type primary. At least three properties of this system allow it to masquerade as a singlemore » star with a very-low-mass companion: its large eccentricity (e {approx} 0.8), its relatively long period (P {approx} 238 days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight ({omega} {approx} 189 Degree-Sign ). As a result of these properties, for {approx}95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e {approx} 0.3). Only during the {approx}5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of {approx}15 km s{sup -1} reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.« less

On the expected relationships among apparent stress, static stress drop, effective shear fracture energy, and efficiency

USGS Publications Warehouse

Beeler, N.M.; Wong, T.-F.; Hickman, S.H.

2003-01-01

We consider expected relationships between apparent stress ??a and static stress drop ????s using a standard energy balance and find ??a = ????s (0.5 - ??), where ?? is stress overshoot. A simple implementation of this balance is to assume overshoot is constant; then apparent stress should vary linearly with stress drop, consistent with spectral theories (Brune, 1970) and dynamic crack models (Madariaga, 1976). Normalizing this expression by the static stress drop defines an efficiency ??sw = ??sa/????s as follows from Savage and Wood (1971). We use this measure of efficiency to analyze data from one of a number of observational studies that find apparent stress to increase with seismic moment, namely earthquakes recorded in the Cajon Pass borehole by Abercrombie (1995). Increases in apparent stress with event size could reflect an increase in seismic efficiency; however, ??sw for the Cajon earthquakes shows no such increase and is approximately constant over the entire moment range. Thus, apparent stress and stress drop co-vary, as expected from the energy balance at constant overshoot. The median value of ??sw for the Cajon earthquakes is four times lower than ??sw for laboratory events. Thus, these Cajon-recorded earthquakes have relatively low and approximately constant efficiency. As the energy balance requires ??sw = 0.5 - ??, overshoot can be estimated directly from the Savage-Wood efficiency; overshoot is positive for Cajon Pass earthquakes. Variations in apparent stress with seismic moment for these earthquakes result primarily from systematic variations in static stress drop with seismic moment and do not require a relative decrease in sliding resistance with increasing event size (dynamic weakening). Based on the comparison of field and lab determinations of the Savage-Wood efficiency, we suggest the criterion ??sw > 0.3 as a test for dynamic weakening in excess of that seen in the lab.

Differential phenolic production in leaves of Vitis vinifera cv. Alvarinho affected with esca disease.

PubMed

Lima, Marta R M; Felgueiras, Mafalda L; Cunha, Ana; Chicau, Gisela; Ferreres, Federico; Dias, Alberto C P

2017-03-01

Esca is a destructive disease of complex etiology affecting grapevines worldwide. A major constraint to the study and control of esca is that the disease is not diagnosed until external leaf and/or fruit symptoms are visible; however external symptoms usually appear several years after infection onset. We studied the phenolic content of V. vinifera cv. Alvarinho leaves using high performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS)/LC-MS. Leaves from affected cordons with and without visible symptoms (diseased and apparently healthy leaves, respectively) and leaves from asymptomatic cordons (healthy leaves) were analyzed. Application of principal components analysis (PCA) to HPLC data showed a clear separation between diseased, apparently healthy, and healthy leaves, with the apparently healthy leaves clustered in a medial position. Several compounds were highly correlated with diseased leaves indicating a differential phenolic production due to esca disease in V. vinifera cv. Alvarinho leaves. Total phenolic production was shown to significantly increase in diseased leaves, compared to healthy leaves, with apparently healthy leaves containing a medial amount. Trans-caffeoyltartaric acid, trans-coumaroyl-tartaric acid, quercetin-3-O-glucoside, quercetin-3-O-galactoside, kaempferol-3-glucoside and myricetin were identified among the compounds associated with disease and their content shown to change similarly to total phenolic production. This study shows that it is possible to discriminate between diseased, healthy and apparently healthy leaves by applying PCA to HPLC data. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

The occultation of 28 Sgr by Saturn - Saturn pole position and astrometry

NASA Technical Reports Server (NTRS)

Hubbard, W. B.; Porco, C. C.; Hunten, D. M.; Rieke, G. H.; Rieke, M. J.; Mccarthy, D. W.; Haemmerle, V.; Clark, R.; Turtle, E. P.; Haller, J.

1993-01-01

Saturn's ring plane-defined pole position is presently derived from the geometry of Saturn's July 3, 1989 occultation of 28 Sgr, as indicated by the timings of 12 circular edges in the Saturn C-ring as well as the edges of the Encke gap and the outer edge of the Keeler gap. The edge timings are used to solve for the position angle and opening angle of the apparent ring ellipses; the internal consistency of the data set and the redundancy of stations indicates an absolute error of the order of 5 km. The pole position thus obtained is consistent with the pole and ring radius scale derived from Voyager occultation observations.

The local lymph node assay being too sensitive?

PubMed

Hans-Werner, Vohr; Jürgen, Ahr Hans

2005-12-01

The local lymph node assay (LLNA) and modifications thereof were recently recognized by the OECD as stand-alone methods for the detection of skin-sensitizing potential. However, although the validity of the LLNA was acknowledged by the ICCVAM, attention was drawn to one major problem, i.e., the possibility of false positive results caused by non-specific cell activation as a result of inflammatory processes in the skin (irritation). This is based on the fact that inflammatory processes in the skin may lead to non-specific activation of dendritic cells, cell migration and non-specific proliferation of lymph node cells. Measuring cell proliferation by radioactive or non-radioactive methods, without taking the irritating properties of test items into account, leads thus to false positive reactions. In this paper, we have compared both endpoints: (1) cell proliferation alone and (2) cell proliferation in combination with inflammatory (irritating) processes. It turned out that a considerable number of tests were "false positive" to the definition mentioned above. By excluding such false positive results the LLNA seems not to be more sensitive than relevant guinea pig assays. These various methods and results are described here.

Analyzing false positives of four questions in the Force Concept Inventory

NASA Astrophysics Data System (ADS)

Yasuda, Jun-ichiro; Mae, Naohiro; Hull, Michael M.; Taniguchi, Masa-aki

2018-06-01

In this study, we analyze the systematic error from false positives of the Force Concept Inventory (FCI). We compare the systematic errors of question 6 (Q.6), Q.7, and Q.16, for which clearly erroneous reasoning has been found, with Q.5, for which clearly erroneous reasoning has not been found. We determine whether or not a correct response to a given FCI question is a false positive using subquestions. In addition to the 30 original questions, subquestions were introduced for Q.5, Q.6, Q.7, and Q.16. This modified version of the FCI was administered to 1145 university students in Japan from 2015 to 2017. In this paper, we discuss our finding that the systematic errors of Q.6, Q.7, and Q.16 are much larger than that of Q.5 for students with mid-level FCI scores. Furthermore, we find that, averaged over the data sample, the sum of the false positives from Q.5, Q.6, Q.7, and Q.16 is about 10% of the FCI score of a midlevel student.

Machine-learning-based real-bogus system for the HSC-SSP moving object detection pipeline

NASA Astrophysics Data System (ADS)

Lin, Hsing-Wen; Chen, Ying-Tung; Wang, Jen-Hung; Wang, Shiang-Yu; Yoshida, Fumi; Ip, Wing-Huen; Miyazaki, Satoshi; Terai, Tsuyoshi

2018-01-01

Machine-learning techniques are widely applied in many modern optical sky surveys, e.g., Pan-STARRS1, PTF/iPTF, and the Subaru/Hyper Suprime-Cam survey, to reduce human intervention in data verification. In this study, we have established a machine-learning-based real-bogus system to reject false detections in the Subaru/Hyper-Suprime-Cam Strategic Survey Program (HSC-SSP) source catalog. Therefore, the HSC-SSP moving object detection pipeline can operate more effectively due to the reduction of false positives. To train the real-bogus system, we use stationary sources as the real training set and "flagged" data as the bogus set. The training set contains 47 features, most of which are photometric measurements and shape moments generated from the HSC image reduction pipeline (hscPipe). Our system can reach a true positive rate (tpr) ˜96% with a false positive rate (fpr) ˜1% or tpr ˜99% at fpr ˜5%. Therefore, we conclude that stationary sources are decent real training samples, and using photometry measurements and shape moments can reject false positives effectively.

Libya: The Transition Clock

DTIC Science & Technology

2012-03-01

particularly important aspect will be the treat- ment of minorities such as the Berbers , who played an important role in the fighting apparently sup- ported by...will insist on the adoption of a strict inter- pretation of Shariah law, a position that led to Berber representatives walking out of at least one

Career Education: Leadership Roles.

ERIC Educational Resources Information Center

Burkett, Lowell A.

With the upsurge of interest in career education and its implementation at all educational levels, the need for leadership in setting goals, establishing policies, and implementing programs is apparent. This paper devotes itself to a discussion of the position which leadership must take for a full expression of the possibilities in the career…

A Test of an Impression Management Interpretation of Public Responses to Positive Inequity.

ERIC Educational Resources Information Center

Rivera, Alba N.; Tedeschi, James T.

Recent evidence indicates that subjects experience "distress" when they are beneficiaries of an inequitable distribution of rewards in a dyad. Yet, reinforcement theory postulates that individuals should experience more pleasure, the greater the reward they receive. An impression management hypothesis would reconcile these apparently opposing…

Effective Yard Supervision: From Needs Assessment to Customized Training

ERIC Educational Resources Information Center

Sharkey, Jill D.; Hunnicutt, Kayleigh L.; Mayworm, Ashley M.; Schiedel, K. Chris; Calcagnotto, Leandro

2014-01-01

Most educational scholars agree that appropriate supervision of children is critical for positive youth development. Supervision is especially important during situations where children have a large degree of freedom and unstructured interaction, such as during recess. Despite the apparent importance of supervision of children at recess, there is…

The Effectiveness of Reward and Punishment Contingencies on Response Inhibition

ERIC Educational Resources Information Center

Costantini, Arthur F.; Hoving, Kenneth L.

1973-01-01

The relative effectiveness of reward and punishment on the development of response inhibition was evaluated developmentally with kindergarteners and second graders. Removal of positive reinforcers was apparently more effective than reward in producing inhibiting at both age levels. Transfer of inhibition training was also evaluated. (DP)

Through the Looking Glass: Symmetry in Behavioral Principles?

ERIC Educational Resources Information Center

Marr, M. Jackson

2006-01-01

In this article, the author discusses and presents seven possibilities that describe how symmetry principles are reflected in behavior analysis. First, if there are apparently no functional distinctions to be made between positive and negative reinforcement, then reinforcer effectiveness (by various measures) is invariant under a simple inversion…

Asymmetries in Predictive and Diagnostic Reasoning

ERIC Educational Resources Information Center

Fernbach, Philip M.; Darlow, Adam; Sloman, Steven A.

2011-01-01

In this article, we address the apparent discrepancy between causal Bayes net theories of cognition, which posit that judgments of uncertainty are generated from causal beliefs in a way that respects the norms of probability, and evidence that probability judgments based on causal beliefs are systematically in error. One purported source of bias…

Marine Bacteria Cause False-Positive Results in the Colilert-18 Rapid Identification Test for Escherichia coli in Florida Waters

PubMed Central

Pisciotta, John M.; Rath, Damon F.; Stanek, Paul A.; Flanery, D. Michael; Harwood, Valerie J.

2002-01-01

The Colilert-18 system for enumeration of total coliforms and Escherichia coli is approved by the U.S. Environmental Protection Agency for use in drinking water analysis and is also used by various agencies and research studies for enumeration of indicator organisms in fresh and saline waters. During monitoring of Pinellas County, Fla., marine waters, estimates of E. coli numbers (by Colilert-18) frequently exceeded fecal coliform counts (by membrane filtration) by 1 to 3 orders of magnitude. Samples from freshwater sites did not display similar discrepancies. Fecal coliforms, including E. coli, could be cultured from 100% of yellow fluorescent wells (denoting E. coli-positive results) inoculated with freshwater samples but could be cultured from only 17.1% of the “positive” wells inoculated with marine samples. Ortho-nitrophenyl-β-d-galactopyranoside (ONPG)-positive or 4-methylumbelliferyl-β-d-glucuronide (MUG)-positive noncoliform bacteria were readily cultured from Colilert-18 test wells inoculated with marine samples. Filtered cell-free seawater did not cause false positives. Coculture preparations of as few as 5 CFU of Vibrio cholerae (ONPG positive) and Providencia sp. (MUG positive) ml−1 inoculated into Colilert-18 caused false-positive E. coli results. Salinity conditions influenced coculture results, as the concentration of coculture inoculum required to cause false positives in most wells increased from about 5 CFU ml−1 in seawater diluted 1:10 with freshwater to ≈5,000 CFU ml−1 in seawater diluted 1:20 with freshwater. Estimated E. coli numbers in various marine water samples processed at the 1:10 dilution ranged from 10 to 7,270 CFU·100 ml−1, while E. coli numbers in the same samples processed at the 1:20 dilution did not exceed 40 CFU·100 ml−1. The lower estimates of E. coli numbers corresponded well with fecal coliform counts by membrane filtration. This study indicates that assessment of E. coli in subtropical marine waters by Colilert-18 is not accurate when the recommended 1:10 sample dilution is used. The results suggest that greater dilution may diminish the false-positive problem, but further study of this possibility is recommended. PMID:11823188

The accuracy of HIV rapid testing in integrated bio-behavioral surveys of men who have sex with men across 5 Provinces in South Africa

PubMed Central

Kufa, Tendesayi; Lane, Tim; Manyuchi, Albert; Singh, Beverley; Isdahl, Zachary; Osmand, Thomas; Grasso, Mike; Struthers, Helen; McIntyre, James; Chipeta, Zawadi; Puren, Adrian

2017-01-01

Abstract We describe the accuracy of serial rapid HIV testing among men who have sex with men (MSM) in South Africa and discuss the implications for HIV testing and prevention. This was a cross-sectional survey conducted at five stand-alone facilities from five provinces. Demographic, behavioral, and clinical data were collected. Dried blood spots were obtained for HIV-related testing. Participants were offered rapid HIV testing using 2 rapid diagnostic tests (RDTs) in series. In the laboratory, reference HIV testing was conducted using a third-generation enzyme immunoassay (EIA) and a fourth-generation EIA as confirmatory. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value, false-positive, and false-negative rates were determined. Between August 2015 and July 2016, 2503 participants were enrolled. Of these, 2343 were tested by RDT on site with a further 2137 (91.2%) having definitive results on both RDT and EIA. Sensitivity, specificity, positive predictive value, negative predictive value, false-positive rates, and false-negative rates were 92.6% [95% confidence interval (95% CI) 89.6–94.8], 99.4% (95% CI 98.9–99.7), 97.4% (95% CI 95.2–98.6), 98.3% (95% CI 97.6–98.8), 0.6% (95% CI 0.3–1.1), and 7.4% (95% CI 5.2–10.4), respectively. False negatives were similar to true positives with respect to virological profiles. Overall accuracy of the RDT algorithm was high, but sensitivity was lower than expected. Post-HIV test counseling should include discussions of possible false-negative results and the need for retesting among HIV negatives. PMID:28700474

MARVELS-1: A Face-on Double-lined Binary Star Masquerading as a Resonant Planetary System and Consideration of Rare False Positives in Radial Velocity Planet Searches

NASA Astrophysics Data System (ADS)

Wright, Jason T.; Roy, Arpita; Mahadevan, Suvrath; Wang, Sharon X.; Ford, Eric B.; Payne, Matt; Lee, Brian L.; Wang, Ji; Crepp, Justin R.; Gaudi, B. Scott; Eastman, Jason; Pepper, Joshua; Ge, Jian; Fleming, Scott W.; Ghezzi, Luan; González-Hernández, Jonay I.; Cargile, Phillip; Stassun, Keivan G.; Wisniewski, John; Dutra-Ferreira, Leticia; Porto de Mello, Gustavo F.; Maia, Márcio A. G.; Nicolaci da Costa, Luiz; Ogando, Ricardo L. C.; Santiago, Basilio X.; Schneider, Donald P.; Hearty, Fred R.

2013-06-01

We have analyzed new and previously published radial velocity (RV) observations of MARVELS-1, known to have an ostensibly substellar companion in a ~6 day orbit. We find significant (~100 m s-1) residuals to the best-fit model for the companion, and these residuals are naïvely consistent with an interior giant planet with a P = 1.965 days in a nearly perfect 3:1 period commensurability (|Pb /Pc - 3| < 10-4). We have performed several tests for the reality of such a companion, including a dynamical analysis, a search for photometric variability, and a hunt for contaminating stellar spectra. We find many reasons to be critical of a planetary interpretation, including the fact that most of the three-body dynamical solutions are unstable. We find no evidence for transits, and no evidence of stellar photometric variability. We have discovered two apparent companions to MARVELS-1 with adaptive optics imaging at Keck; both are M dwarfs, one is likely bound, and the other is likely a foreground object. We explore false-alarm scenarios inspired by various curiosities in the data. Ultimately, a line profile and bisector analysis lead us to conclude that the ~100 m s-1 residuals are an artifact of spectral contamination from a stellar companion contributing ~15%-30% of the optical light in the system. We conclude that origin of this contamination is the previously detected RV companion to MARVELS-1, which is not, as previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit.

Laxative-free CT colonography.

PubMed

Slater, A; Betts, M; D'Costa, H

2012-08-01

The aim of this study was to determine if the introduction of faecal tagging to CT colonography (CTC) made the examination easier to tolerate or reduced the number of false-positives. Our department changed bowel preparation for CT colonography from Picolax (Ferring Pharmaceuticals Ltd, London, UK) to Gastrografin (Bracco Diagnostics Inc, Princeton, NJ) only with a modified diet. Questionnaires were given to a subgroup of patients within these cohorts. The numbers of false-positives were compared between two cohorts before and after this change. false-positives were defined as lesions reported on CT that were not confirmed by subsequent endoscopic examination. Polyps were matched if they were in the same or adjacent segments, and were within 5 mm of the reported size. 412 patients were identified from the Picolax cohort, and 116 from the Gastrografin cohort. 62 patients in each group completed questionnaires. Gastrografin produced less diarrhoea; 34% had five or more bowel motions in the previous day and night, compared with 77% for Picolax (p<0.001), although more patients found drinking it unpleasant compared with Picolax (85% reported drinking Picolax as "easy" vs 61% for Gastrografin; p=0.002). Picolax produced more non-diagnostic examinations, although this difference was not statistically significant. There was not a significant reduction in the numbers of false-positives (2 out of 112 for Gastrografin group, 14 out of 389 for the Picolax group; p=0.54). Switching from Picolax to Gastrografin as a CTC preparation technique produced less diarrhoea, but did not reduce the number of false-positives.

When a Step Is Not a Step! Specificity Analysis of Five Physical Activity Monitors.

PubMed

O'Connell, Sandra; ÓLaighin, Gearóid; Quinlan, Leo R

2017-01-01

Physical activity is an essential aspect of a healthy lifestyle for both physical and mental health states. As step count is one of the most utilized measures for quantifying physical activity it is important that activity-monitoring devices be both sensitive and specific in recording actual steps taken and disregard non-stepping body movements. The objective of this study was to assess the specificity of five activity monitors during a variety of prescribed non-stepping activities. Participants wore five activity monitors simultaneously for a variety of prescribed activities including deskwork, taking an elevator, taking a bus journey, automobile driving, washing and drying dishes; functional reaching task; indoor cycling; outdoor cycling; and indoor rowing. Each task was carried out for either a specific duration of time or over a specific distance. Activity monitors tested were the ActivPAL micro™, NL-2000™ pedometer, Withings Smart Activity Monitor Tracker (Pulse O2)™, Fitbit One™ and Jawbone UP™. Participants were video-recorded while carrying out the prescribed activities and the false positive step count registered on each activity monitor was obtained and compared to the video. All activity monitors registered a significant number of false positive steps per minute during one or more of the prescribed activities. The Withings™ activity performed best, registering a significant number of false positive steps per minute during the outdoor cycling activity only (P = 0.025). The Jawbone™ registered a significant number of false positive steps during the functional reaching task and while washing and drying dishes, which involved arm and hand movement (P < 0.01 for both). The ActivPAL™ registered a significant number of false positive steps during the cycling exercises (P < 0.001 for both). As a number of false positive steps were registered on the activity monitors during the non-stepping activities, the authors conclude that non-stepping physical activities can result in the false detection of steps. This can negatively affect the quantification of physical activity with regard to step count as an output. The Withings™ activity monitor performed best with regard to specificity during the activities of daily living tested.

False-Positive Rate of AKI Using Consensus Creatinine-Based Criteria.

PubMed

Lin, Jennie; Fernandez, Hilda; Shashaty, Michael G S; Negoianu, Dan; Testani, Jeffrey M; Berns, Jeffrey S; Parikh, Chirag R; Wilson, F Perry

2015-10-07

Use of small changes in serum creatinine to diagnose AKI allows for earlier detection but may increase diagnostic false-positive rates because of inherent laboratory and biologic variabilities of creatinine. We examined serum creatinine measurement characteristics in a prospective observational clinical reference cohort of 2267 adult patients with AKI by Kidney Disease Improving Global Outcomes creatinine criteria and used these data to create a simulation cohort to model AKI false-positive rates. We simulated up to seven successive blood draws on an equal population of hypothetical patients with unchanging true serum creatinine values. Error terms generated from laboratory and biologic variabilities were added to each simulated patient's true serum creatinine value to obtain the simulated measured serum creatinine for each blood draw. We determined the proportion of patients who would be erroneously diagnosed with AKI by Kidney Disease Improving Global Outcomes creatinine criteria. Within the clinical cohort, 75.0% of patients received four serum creatinine draws within at least one 48-hour period during hospitalization. After four simulated creatinine measurements that accounted for laboratory variability calculated from assay characteristics and 4.4% of biologic variability determined from the clinical cohort and publicly available data, the overall false-positive rate for AKI diagnosis was 8.0% (interquartile range =7.9%-8.1%), whereas patients with true serum creatinine ≥1.5 mg/dl (representing 21% of the clinical cohort) had a false-positive AKI diagnosis rate of 30.5% (interquartile range =30.1%-30.9%) versus 2.0% (interquartile range =1.9%-2.1%) in patients with true serum creatinine values <1.5 mg/dl (P<0.001). Use of small serum creatinine changes to diagnose AKI is limited by high false-positive rates caused by inherent variability of serum creatinine at higher baseline values, potentially misclassifying patients with CKD in AKI studies. Copyright © 2015 by the American Society of Nephrology.

The Diagnostic Validity of Citric Acid-Free, High Dose (13)C-Urea Breath Test After Helicobacter pylori Eradication in Korea.

PubMed

Kwon, Yong Hwan; Kim, Nayoung; Lee, Ju Yup; Choi, Yoon Jin; Yoon, Kichul; Hwang, Jae Jin; Lee, Hyun Joo; Lee, AeRa; Jeong, Yeon Sang; Oh, Sooyeon; Yoon, Hyuk; Shin, Cheol Min; Park, Young Soo; Lee, Dong Ho

2015-06-01

The (13)C-urea breath test ((13)C-UBT) is a noninvasive method for diagnosing Helicobacter pylori (H. pylori) infection. The aims of this study were to evaluate the diagnostic validity of the (13)C-UBT cutoff value and to identify influencing clinical factors responsible for aberrant results. (13)C-UBT (UBiTkit; Otsuka Pharmaceutical, cutoff value: 2.5‰) results in the range 2.0‰ to 10.0‰ after H. pylori eradication therapy were compared with the results of endoscopic biopsy results of the antrum and body. Factors considered to affect test results adversely were analyzed. Among patients with a positive (13)C-UBT result (2.5‰ to 10.0‰, n = 223) or a negative (13)C-UBT result (2.0‰ to < 2.5‰, n = 66) after H. pylori eradication, 73 patients (34.0%) were false positive, and one (1.5%) was false negative as determined by endoscopic biopsy. The sensitivity, specificity, false-positive rate, and false-negative rate for a cutoff value of 2.5‰ were 99.3%, 47.1%, 52.9%, and 0.7%, respectively, and positive and negative predictive values of the (13)C-UBT were 67.3% and 98.5%, respectively. Multivariate analysis showed that a history of two or more previous H. pylori eradication therapies (OR = 2.455, 95%CI = 1.299-4.641) and moderate to severe gastric intestinal metaplasia (OR = 3.359, 95%CI = 1.572-7.178) were associated with a false-positive (13)C-UBT result. The (13)C-UBT cutoff value currently used has poor specificity for confirming H. pylori status after eradication, and this lack of specificity is exacerbated in patients that have undergone multiple prior eradication therapies and in patients with moderate to severe gastric intestinal metaplasia. In addition, the citric-free (13)C-UBT would increase a false-positive (13)C-UBT result. © 2015 John Wiley & Sons Ltd.

Randomly auditing research labs could be an affordable way to improve research quality: A simulation study

PubMed Central

Zardo, Pauline; Graves, Nicholas

2018-01-01

The “publish or perish” incentive drives many researchers to increase the quantity of their papers at the cost of quality. Lowering quality increases the number of false positive errors which is a key cause of the reproducibility crisis. We adapted a previously published simulation of the research world where labs that produce many papers are more likely to have “child” labs that inherit their characteristics. This selection creates a competitive spiral that favours quantity over quality. To try to halt the competitive spiral we added random audits that could detect and remove labs with a high proportion of false positives, and also improved the behaviour of “child” and “parent” labs who increased their effort and so lowered their probability of making a false positive error. Without auditing, only 0.2% of simulations did not experience the competitive spiral, defined by a convergence to the highest possible false positive probability. Auditing 1.35% of papers avoided the competitive spiral in 71% of simulations, and auditing 1.94% of papers in 95% of simulations. Audits worked best when they were only applied to established labs with 50 or more papers compared with labs with 25 or more papers. Adding a ±20% random error to the number of false positives to simulate peer reviewer error did not reduce the audits’ efficacy. The main benefit of the audits was via the increase in effort in “child” and “parent” labs. Audits improved the literature by reducing the number of false positives from 30.2 per 100 papers to 12.3 per 100 papers. Auditing 1.94% of papers would cost an estimated $15.9 million per year if applied to papers produced by National Institutes of Health funding. Our simulation greatly simplifies the research world and there are many unanswered questions about if and how audits would work that can only be addressed by a trial of an audit. PMID:29649314

Randomly auditing research labs could be an affordable way to improve research quality: A simulation study.

PubMed

Barnett, Adrian G; Zardo, Pauline; Graves, Nicholas

2018-01-01

The "publish or perish" incentive drives many researchers to increase the quantity of their papers at the cost of quality. Lowering quality increases the number of false positive errors which is a key cause of the reproducibility crisis. We adapted a previously published simulation of the research world where labs that produce many papers are more likely to have "child" labs that inherit their characteristics. This selection creates a competitive spiral that favours quantity over quality. To try to halt the competitive spiral we added random audits that could detect and remove labs with a high proportion of false positives, and also improved the behaviour of "child" and "parent" labs who increased their effort and so lowered their probability of making a false positive error. Without auditing, only 0.2% of simulations did not experience the competitive spiral, defined by a convergence to the highest possible false positive probability. Auditing 1.35% of papers avoided the competitive spiral in 71% of simulations, and auditing 1.94% of papers in 95% of simulations. Audits worked best when they were only applied to established labs with 50 or more papers compared with labs with 25 or more papers. Adding a ±20% random error to the number of false positives to simulate peer reviewer error did not reduce the audits' efficacy. The main benefit of the audits was via the increase in effort in "child" and "parent" labs. Audits improved the literature by reducing the number of false positives from 30.2 per 100 papers to 12.3 per 100 papers. Auditing 1.94% of papers would cost an estimated $15.9 million per year if applied to papers produced by National Institutes of Health funding. Our simulation greatly simplifies the research world and there are many unanswered questions about if and how audits would work that can only be addressed by a trial of an audit.

Age and trophic position dominate bioaccumulation of mercury and organochlorines in the food web of Lake Washington

USGS Publications Warehouse

McIntyre, J.K.; Beauchamp, D.A.

2007-01-01

Understanding the mechanisms of bioaccumulation in food webs is critical to predicting which food webs are at risk for higher rates of bioaccumulation that endanger the health of upper-trophic predators, including humans. Mercury and organochlorines were measured concurrently with stable isotopes of nitrogen and carbon in key fishes and invertebrates of Lake Washington to explore important pathways of bioaccumulation in this food web. Across the food web, age and trophic position together were highly significant predictors of bioaccumulation. Trophic position was more important than age for predicting accumulation of mercury, ???DDT, and ???-chlordane, whereas age was more important than trophic position for predicting ???PCB. Excluding age from the analysis inflated the apparent importance of trophic position to bioaccumulation for all contaminants. Benthic and pelagic habitats had similar potential to bioaccumulate contaminants, although higher ???-chlordane concentrations in organisms were weakly associated with more benthic carbon signals. In individual fish species, contaminant concentrations increased with age, size, and trophic position (??15N), whereas relationships with carbon source (??13C) were not consistent. Lipid concentrations were correlated with contaminant concentrations in some but not all fishes, suggesting that lipids were not involved mechanistically in bioaccumulation. Contaminant concentrations in biota did not vary among littoral sites. Collectively, these results suggest that age may be an important determinant of bioaccumulation in many food webs and could help explain a significant amount of the variability in apparent biomagnification rates among food webs. As such, effort should be made when possible to collect information on organism age in addition to stable isotopes when assessing food webs for rates of biomagnification. ?? 2006 Elsevier B.V. All rights reserved.

Parametric vs. non-parametric statistics of low resolution electromagnetic tomography (LORETA).

PubMed

Thatcher, R W; North, D; Biver, C

2005-01-01

This study compared the relative statistical sensitivity of non-parametric and parametric statistics of 3-dimensional current sources as estimated by the EEG inverse solution Low Resolution Electromagnetic Tomography (LORETA). One would expect approximately 5% false positives (classification of a normal as abnormal) at the P < .025 level of probability (two tailed test) and approximately 1% false positives at the P < .005 level. EEG digital samples (2 second intervals sampled 128 Hz, 1 to 2 minutes eyes closed) from 43 normal adult subjects were imported into the Key Institute's LORETA program. We then used the Key Institute's cross-spectrum and the Key Institute's LORETA output files (*.lor) as the 2,394 gray matter pixel representation of 3-dimensional currents at different frequencies. The mean and standard deviation *.lor files were computed for each of the 2,394 gray matter pixels for each of the 43 subjects. Tests of Gaussianity and different transforms were computed in order to best approximate a normal distribution for each frequency and gray matter pixel. The relative sensitivity of parametric vs. non-parametric statistics were compared using a "leave-one-out" cross validation method in which individual normal subjects were withdrawn and then statistically classified as being either normal or abnormal based on the remaining subjects. Log10 transforms approximated Gaussian distribution in the range of 95% to 99% accuracy. Parametric Z score tests at P < .05 cross-validation demonstrated an average misclassification rate of approximately 4.25%, and range over the 2,394 gray matter pixels was 27.66% to 0.11%. At P < .01 parametric Z score cross-validation false positives were 0.26% and ranged from 6.65% to 0% false positives. The non-parametric Key Institute's t-max statistic at P < .05 had an average misclassification error rate of 7.64% and ranged from 43.37% to 0.04% false positives. The nonparametric t-max at P < .01 had an average misclassification rate of 6.67% and ranged from 41.34% to 0% false positives of the 2,394 gray matter pixels for any cross-validated normal subject. In conclusion, adequate approximation to Gaussian distribution and high cross-validation can be achieved by the Key Institute's LORETA programs by using a log10 transform and parametric statistics, and parametric normative comparisons had lower false positive rates than the non-parametric tests.

The reproducibility of research and the misinterpretation of p-values

PubMed Central

2017-01-01

We wish to answer this question: If you observe a ‘significant’ p-value after doing a single unbiased experiment, what is the probability that your result is a false positive? The weak evidence provided by p-values between 0.01 and 0.05 is explored by exact calculations of false positive risks. When you observe p = 0.05, the odds in favour of there being a real effect (given by the likelihood ratio) are about 3 : 1. This is far weaker evidence than the odds of 19 to 1 that might, wrongly, be inferred from the p-value. And if you want to limit the false positive risk to 5%, you would have to assume that you were 87% sure that there was a real effect before the experiment was done. If you observe p = 0.001 in a well-powered experiment, it gives a likelihood ratio of almost 100 : 1 odds on there being a real effect. That would usually be regarded as conclusive. But the false positive risk would still be 8% if the prior probability of a real effect were only 0.1. And, in this case, if you wanted to achieve a false positive risk of 5% you would need to observe p = 0.00045. It is recommended that the terms ‘significant’ and ‘non-significant’ should never be used. Rather, p-values should be supplemented by specifying the prior probability that would be needed to produce a specified (e.g. 5%) false positive risk. It may also be helpful to specify the minimum false positive risk associated with the observed p-value. Despite decades of warnings, many areas of science still insist on labelling a result of p < 0.05 as ‘statistically significant’. This practice must contribute to the lack of reproducibility in some areas of science. This is before you get to the many other well-known problems, like multiple comparisons, lack of randomization and p-hacking. Precise inductive inference is impossible and replication is the only way to be sure. Science is endangered by statistical misunderstanding, and by senior people who impose perverse incentives on scientists. PMID:29308247

Predictive Value of Parkinsonian Primates in Pharmacologic Studies: A Comparison between the Macaque, Marmoset, and Squirrel Monkey.

PubMed

Veyres, Nicolas; Hamadjida, Adjia; Huot, Philippe

2018-05-01

The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned primate is the gold-standard animal model of Parkinson disease (PD) and has been used to assess the effectiveness of experimental drugs on dyskinesia, parkinsonism, and psychosis. Three species have been used in most studies-the macaque, marmoset, and squirrel monkey-the last much less so than the first two species; however, the predictive value of each species at forecasting clinical efficacy, or lack thereof, is poorly documented. Here, we have reviewed all the published literature detailing pharmacologic studies that assessed the effects of experimental drugs on dyskinesia, parkinsonism, and psychosis in each of these species and have calculated their predictive value of success and failure at the clinical level. We found that, for dyskinesia, the macaque has a positive predictive value of 87.5% and a false-positive rate of 38.1%, whereas the marmoset has a positive predictive value of 76.9% and a false-positive rate of 15.6%. For parkinsonism, the macaque has a positive predictive value of 68.2% and a false-positive rate of 44.4%, whereas the marmoset has a positive predictive value of 86.9% and a false-positive rate of 41.7%. No drug that alleviates psychosis in the clinic has shown efficacy at doing so in the macaque, whereas the marmoset has 100% positive predictive value. The small number of studies conducted in the squirrel monkey precluded us from calculating its predictive efficacy. We hope our results will help in the design of pharmacologic experiments and will facilitate the drug discovery and development process in PD. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

Mixed group validation: a method to address the limitations of criterion group validation in research on malingering detection.

PubMed

Frederick, R I

2000-01-01

Mixed group validation (MGV) is offered as an alternative to criterion group validation (CGV) to estimate the true positive and false positive rates of tests and other diagnostic signs. CGV requires perfect confidence about each research participant's status with respect to the presence or absence of pathology. MGV determines diagnostic efficiencies based on group data; knowing an individual's status with respect to pathology is not required. MGV can use relatively weak indicators to validate better diagnostic signs, whereas CGV requires perfect diagnostic signs to avoid error in computing true positive and false positive rates. The process of MGV is explained, and a computer simulation demonstrates the soundness of the procedure. MGV of the Rey 15-Item Memory Test (Rey, 1958) for 723 pre-trial criminal defendants resulted in higher estimates of true positive rates and lower estimates of false positive rates as compared with prior research conducted with CGV. The author demonstrates how MGV addresses all the criticisms Rogers (1997b) outlined for differential prevalence designs in malingering detection research. Copyright 2000 John Wiley & Sons, Ltd.

Influence of humic acids of different origins on oxidation of phenol and chlorophenols by permanganate.

PubMed

He, Di; Guan, Xiaohong; Ma, Jun; Yang, Xue; Cui, Chongwei

2010-10-15

The influences of humic acids (HAs) of different origins, including two commercial HAs, three soil HAs and one aquatic HA, on phenols oxidation by permanganate were studied. The apparent second-order rate constants of 2-chlorophenol (2-CP)/phenol oxidation by permanganate in the presence of HAs at pH 7 followed the order of commercial HA (Shanghai)>soil HAs>commercial HA (Fluka)>aquatic HA. Moreover, the commercial HA (Shanghai) could accelerate the oxidation of different chlorophenols (CP) significantly under neutral condition. The FTIR analysis demonstrated greater content of CC moieties and less amount of carboxylate, aliphatic groups and polysaccharide-like substances in soil HAs than in aqueous HA, suggesting that the increase of aromaticity in HA was beneficial to the oxidation of phenols by permanganate. The apparent second-order rate constants of 2-CP/phenol oxidation by permanganate in the presence of HAs correlated well with specific visible absorption (SVA) at 665 nm of HAs. High positive correlation coefficients (R(2)>0.75) implied that pi-electrons of HA strongly influenced the reactivity of 2-CP/phenol towards permanganate oxidation, which agreed well with positive correlation between Fluorescence Regional Integration (FRI) and the apparent second-order rate constants. The pi-pi interaction between HAs and phenols, the steric hindrance effect and the dissociation of phenols may affect the oxidation of phenols by permanganate in the presence of HA at pH=7.0. 2010 Elsevier B.V. All rights reserved.

Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso

PubMed Central

2013-01-01

Background The Anopheles gambiae sensu lato (s.l.) species complex in Burkina Faso consists of Anopheles arabiensis, and molecular forms M and S of Anopheles gambiae sensu stricto (s.s.). Previous studies comparing the M and S forms for level of infection with Plasmodium falciparum have yielded conflicting results. Methods Mosquito larvae were sampled from natural pools, reared to adulthood under controlled conditions, and challenged with natural P. falciparum by experimental feeding with blood from gametocyte carriers. Oocyst infection prevalence and intensity was determined one week after infection. DNA from carcasses was genotyped to identify species and molecular form. Results In total, 7,400 adult mosquitoes grown from wild-caught larvae were challenged with gametocytes in 29 experimental infections spanning four transmission seasons. The overall infection prevalence averaged 40.7% for A. gambiae M form, 41.4% for A. gambiae S form, and 40.1% for A. arabiensis. There was no significant difference in infection prevalence or intensity between the three population groups. Notably, infection experiments in which the population groups were challenged in parallel on the same infective blood displayed less infection difference between population groups, while infections with less balanced composition of population groups had lower statistical power and displayed apparent differences that fluctuated more often from the null average. Conclusion The study clearly establishes that, at the study site in Burkina Faso, there is no difference in genetic susceptibility to P. falciparum infection between three sympatric population groups of the A. gambiae s.l. complex. Feeding the mosquito groups on the same infective blood meal greatly increases statistical power. Conversely, comparison of the different mosquito groups between, rather than within, infections yields larger apparent difference between mosquito groups, resulting from lower statistical power and greater noise, and could lead to false-positive results. In making infection comparisons between population groups, it is more accurate to compare the different groups after feeding simultaneously upon the same infective blood. PMID:23764031

Evaluation of inadequate, indeterminate, false-negative and false-positive cases in cytological examination for breast cancer according to histological type

PubMed Central

2012-01-01

Background We previously investigated the current status of breast cytology cancer screening at seven institutes in our area of southern Fukuoka Prefecture, and found some differences in diagnostic accuracy among the institutions. In the present study, we evaluated the cases involved and noted possible reasons for their original cytological classification as inadequate, indeterminate, false-negative and false-positive according to histological type. Methods We evaluated the histological findings in 5693 individuals who underwent cytological examination for breast cancer (including inadequate, indeterminate, false-negative and false-positive cases), to determine the most common histological types and/or features in these settings and the usefulness/limitations of cytological examination for the diagnosis of breast cancer. Results Among 1152 cytologically inadequate cases, histology revealed that 75/173 (43.6%) cases were benign, including mastopathy (fibrocystic disease) in 38.6%, fibroadenoma in 24.0% and papilloma in 5.3%. Ninety-five of 173 (54.9%) cases were histologically malignant, with scirrhous growing type, invasive ductal carcinoma (SIDC) being significantly more frequent (49.5%) than papillotubular growing type (Papi-tub) (P < 0.0001), solid-tubular growing type (P = 0.0001) and ductal carcinoma in situ (DCIS) (P = 0.0001). Among 458 indeterminate cases, 54/139 (38.8%) were histologically benign (mastopathy, 30.0%; fibroadenoma, 27.8%; papilloma, 26.0%) and 73/139 (52.5%) were malignant, with SIDC being the most frequent malignant tumor (37.0%). Among 52 false-negative cases, SIDC was significantly more frequent (42.3%) than DCIS (P = 0.0049) and Papi-tub (P = 0.001). There were three false-positive cases, with one each of fibroadenoma, epidermal cyst and papilloma. Conclusions The inadequate, indeterminate, false-negative and false-positive cases showed similar histological types, notably SIDC for malignant tumors, and mastopathy, fibroadenoma and papilloma for benign cases. We need to pay particular attention to the collection and assessment of aspirates for these histological types of breast disease. In particular, several inadequate, indeterminate and false-negative cases with samples collected by aspiration were diagnosed as SIDC. These findings should encourage the use of needle biopsy rather than aspiration when this histological type is identified on imaging. Namely, good communication between clinicians and pathological staff, and triple assessment (i.e., clinical, pathological and radiological assessment), are important for accurate diagnosis of aspiration samples. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7349809170055423 PMID:22607447

Moon and Sun shadowing effect in the MACRO detector

NASA Astrophysics Data System (ADS)

Ambrosio, M.; Antolini, R.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Chiarusi, T.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; De Cataldo, G.; Dekhissi, H.; De Marzo, C.; De Mitri, I.; Derkaoui, J.; De Vincenzi, M.; Di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kumar, A.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Manzoor, S.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.

2003-11-01

Using data collected by the MACRO experiment from 1989 to the end of its operations in 2000, we have studied in the underground muon flux the shadowing effects due to both the Moon and the Sun. We have observed the shadow cast by the Moon at its apparent position with a significance of 6.5 σ. The Moon shadowing effect has been used to verify the pointing capability of the detector and to determine the instrument resolution for the search of muon excesses from any direction of the celestial sphere. The dependence of the effect on the geomagnetic field is clearly shown by splitting the data sample in day and night observations. The Sun shadow, observed with a significance of 4.6 σ is displaced by about 0.6° from its apparent position. In this case however the explanation resides in the configuration of the Solar and Interplanetary Magnetic Fields, which affect the propagation of cosmic ray particles between the Sun, and the Earth. The displacement of the Sun shadow with respect to the real Sun position has been used to establish an upper limit on the antimatter flux in cosmic rays of about 48% at 68% c.l. and primary energies of about 20 TeV.

Six years' experience of using the BacT/ALERT system to screen all platelet concentrates, and additional testing of outdated platelet concentrates to estimate the frequency of false-negative results.

PubMed

Larsen, C P; Ezligini, F; Hermansen, N O; Kjeldsen-Kragh, J

2005-02-01

Approximately 1 in every 2000 units of platelets is contaminated with bacteria. The BacT/ALERT automated blood culture system can be used to screen platelet concentrates (PCs) for bacterial contamination. Data were collected from May 1998 until May 2004. The number of PCs tested during this period was 36 896, most of which were produced from pools of four buffy-coats. On the day following blood collection or platelet apheresis, a 5-10 ml sample of the PC was aseptically transferred to a BacT/ALERT culture bottle for detection of aerobic bacteria. The sample was monitored for bacterial growth during the entire storage period of the PC (6.5 days). When a positive signal was generated, the culture bottle, the PC and the erythrocyte concentrates were tested for bacterial growth. In order to determine the frequency of false-negative BacT/ALERT signals, 1061 outdated PCs were tested during the period from May 2002 to May 2004. Eighty-eight positive signals were detected by the BacT/ALERT system, of which 12 were interpreted as truly positive. Fourteen signals were interpreted as truly false positive. Thirty-three signals were interpreted to be probably false positive. Two of 1061 outdated units tested positive, and Bacillus spp. and Staphylococcus epidermidis, respectively, were isolated from these PCs. Between 0.03% and 0.12% of the PCs were contaminated with bacteria. BacT/ALERT is an efficient tool for monitoring PCs for bacterial contamination; however, it is important to realize that false-negative results may occur.

Impact of false-negative sentinel lymph node biopsy on survival in patients with cutaneous melanoma.

PubMed

Caracò, C; Marone, U; Celentano, E; Botti, G; Mozzillo, N

2007-09-01

Sentinel lymph node biopsy is widely accepted as standard care in melanoma despite lack of pertinent randomized trials results. A possible pitfall of this procedure is the inaccurate identification of the sentinel lymph node leading to biopsy and analysis of a nonsentinel node. Such a technical failure may yield a different prognosis. The purpose of this study is to analyze the incidence of false negativity and its impact on clinical outcome and to try to understand its causes. The Melanoma Data Base at National Cancer Institute of Naples was analyzed comparing results between false-negative and tumor-positive sentinel node patients focusing on overall survival and prognostic factors influencing the clinical outcome. One hundred fifty-one cases were diagnosed to be tumor-positive after sentinel lymph node biopsy and were subjected to complete lymph node dissection. Thirty-four (18.4%)patients with tumor-negative sentinel node subsequently developed lymph node metastases in the basin site of the sentinel procedure. With a median follow-up of 42.8 months the 5-year overall survival was 48.4% and 66.3% for false-negative and tumor-positive group respectively with significant statistical differences (P < .03). The sensitivity of sentinel lymph node biopsy was 81.6%, and a regional nodal basin recurrence after negative-sentinel node biopsy means a worse prognosis, compared with patients submitted to complete lymph node dissection after a positive sentinel biopsy. The evidence of higher number of tumor-positive nodes after delayed lymphadenectomy in false-negative group compared with tumor-positive sentinel node cases, confirmed the importance of an early staging of lymph nodal involvement. Further data will better clarify the role of prognostic factors to identify cases with a more aggressive biological behavior of the disease.

Automated Detection, Localization, and Classification of Traumatic Vertebral Body Fractures in the Thoracic and Lumbar Spine at CT

PubMed Central

Burns, Joseph E.; Yao, Jianhua; Muñoz, Hector

2016-01-01

Purpose To design and validate a fully automated computer system for the detection and anatomic localization of traumatic thoracic and lumbar vertebral body fractures at computed tomography (CT). Materials and Methods This retrospective study was HIPAA compliant. Institutional review board approval was obtained, and informed consent was waived. CT examinations in 104 patients (mean age, 34.4 years; range, 14–88 years; 32 women, 72 men), consisting of 94 examinations with positive findings for fractures (59 with vertebral body fractures) and 10 control examinations (without vertebral fractures), were performed. There were 141 thoracic and lumbar vertebral body fractures in the case set. The locations of fractures were marked and classified by a radiologist according to Denis column involvement. The CT data set was divided into training and testing subsets (37 and 67 subsets, respectively) for analysis by means of prototype software for fully automated spinal segmentation and fracture detection. Free-response receiver operating characteristic analysis was performed. Results Training set sensitivity for detection and localization of fractures within each vertebra was 0.82 (28 of 34 findings; 95% confidence interval [CI]: 0.68, 0.90), with a false-positive rate of 2.5 findings per patient. The sensitivity for fracture localization to the correct vertebra was 0.88 (23 of 26 findings; 95% CI: 0.72, 0.96), with a false-positive rate of 1.3. Testing set sensitivity for the detection and localization of fractures within each vertebra was 0.81 (87 of 107 findings; 95% CI: 0.75, 0.87), with a false-positive rate of 2.7. The sensitivity for fracture localization to the correct vertebra was 0.92 (55 of 60 findings; 95% CI: 0.79, 0.94), with a false-positive rate of 1.6. The most common cause of false-positive findings was nutrient foramina (106 of 272 findings [39%]). Conclusion The fully automated computer system detects and anatomically localizes vertebral body fractures in the thoracic and lumbar spine on CT images with a high sensitivity and a low false-positive rate. © RSNA, 2015 Online supplemental material is available for this article. PMID:26172532

Multi-Stage System for Automatic Target Recognition

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin; Lu, Thomas T.; Ye, David; Edens, Weston; Johnson, Oliver

2010-01-01

A multi-stage automated target recognition (ATR) system has been designed to perform computer vision tasks with adequate proficiency in mimicking human vision. The system is able to detect, identify, and track targets of interest. Potential regions of interest (ROIs) are first identified by the detection stage using an Optimum Trade-off Maximum Average Correlation Height (OT-MACH) filter combined with a wavelet transform. False positives are then eliminated by the verification stage using feature extraction methods in conjunction with neural networks. Feature extraction transforms the ROIs using filtering and binning algorithms to create feature vectors. A feedforward back-propagation neural network (NN) is then trained to classify each feature vector and to remove false positives. The system parameter optimizations process has been developed to adapt to various targets and datasets. The objective was to design an efficient computer vision system that can learn to detect multiple targets in large images with unknown backgrounds. Because the target size is small relative to the image size in this problem, there are many regions of the image that could potentially contain the target. A cursory analysis of every region can be computationally efficient, but may yield too many false positives. On the other hand, a detailed analysis of every region can yield better results, but may be computationally inefficient. The multi-stage ATR system was designed to achieve an optimal balance between accuracy and computational efficiency by incorporating both models. The detection stage first identifies potential ROIs where the target may be present by performing a fast Fourier domain OT-MACH filter-based correlation. Because threshold for this stage is chosen with the goal of detecting all true positives, a number of false positives are also detected as ROIs. The verification stage then transforms the regions of interest into feature space, and eliminates false positives using an artificial neural network classifier. The multi-stage system allows tuning the detection sensitivity and the identification specificity individually in each stage. It is easier to achieve optimized ATR operation based on its specific goal. The test results show that the system was successful in substantially reducing the false positive rate when tested on a sonar and video image datasets.

The semantics of emotion in false memory.

PubMed

Brainerd, C J; Bookbinder, S H

2018-03-26

The emotional valence of target information has been a centerpiece of recent false memory research, but in most experiments, it has been confounded with emotional arousal. We sought to clarify the results of such research by identifying a shared mathematical relation between valence and arousal ratings in commonly administered normed materials. That relation was then used to (a) decide whether arousal as well as valence influences false memory when they are confounded and to (b) determine whether semantic properties that are known to affect false memory covary with valence and arousal ratings. In Study 1, we identified a quadratic relation between valence and arousal ratings of words and pictures that has 2 key properties: Arousal increases more rapidly as function of negative valence than positive valence, and hence, a given level of negative valence is more arousing than the same level of positive valence. This quadratic function predicts that if arousal as well as valence affects false memory when they are confounded, false memory data must have certain fine-grained properties. In Study 2, those properties were absent from norming data for the Cornell-Cortland Emotional Word Lists, indicating that valence but not arousal affects false memory in those norms. In Study 3, we tested fuzzy-trace theory's explanation of that pattern: that valence ratings are positively related to semantic properties that are known to increase false memory, but arousal ratings are not. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

False positive or negative results of shear-wave elastography in differentiating benign from malignant breast masses: analysis of clinical and ultrasonographic characteristics.

PubMed

Kim, Mi Young; Choi, Nami; Yang, Jung-Hyun; Yoo, Young Bum; Park, Kyoung Sik

2015-10-01

Shear-wave elastography (SWE) has the potential to improve diagnostic performance of conventional ultrasound (US) in differentiating benign from malignant breast masses. To investigate false positive or negative results of SWE in differentiating benign from malignant breast masses and to analyze clinical and imaging characteristics of the masses with false SWE findings. From May to October 2013, 166 breast lesions of 164 consecutive women (mean age, 45.3 ± 10.1 years) who had been scheduled for biopsy were included. Conventional US and SWE were performed in all women before biopsy. Clinical, ultrasonographic morphologic features and SWE parameters (pattern classification and standard deviation [SD]) were recorded and compared with the histopathology results. Patient and lesion factors in the "true" and "false" groups were compared. Of the 166 masses, 118 (71.1%) were benign and 48 (28.9%) were malignant. False SWE features were more frequently observed in benign masses. False positive rates of benign masses and false negative rates of malignancy were 53% and 8.2%, respectively, using SWE pattern analysis and were 22.4% and 10.3%, respectively, using SD values. A lesion boundary of the masses on US (P = 0.039) and younger patient age (P = 0.047) were significantly associated with false SWE findings. These clinical and ultrasonographic features need to be carefully evaluated in performance and interpretation of SWE examinations. © The Foundation Acta Radiologica 2014.

Detecting False Positives in Multielement Designs: Implications for Brief Assessments

ERIC Educational Resources Information Center

Bartlett, Sara M.; Rapp, John T.; Henrickson, Marissa L.

2011-01-01

The authors assessed the extent to which multielement designs produced false positives using continuous duration recording (CDR) and interval recording with 10-s and 1-min interval sizes. Specifically, they created 6,000 graphs with multielement designs that varied in the number of data paths, and the number of data points per data path, using a…

IS HCI THAT IS USED AS A PRESERVATIVE CREATING FALSE POSITIVES FOR TBA IN GROUND WATER

EPA Science Inventory

Will hydrochloric acid produce false positives for TBA? Yes, if you heat the sample to get a lower detection limit for TBA. Conventional purge and trap methods at ambient temperature have a reporting limit for TBA between 50 and 100 g/liter. This is higher than the provisiona...

False Positives in Multiple Regression: Unanticipated Consequences of Measurement Error in the Predictor Variables

ERIC Educational Resources Information Center

Shear, Benjamin R.; Zumbo, Bruno D.

2013-01-01

Type I error rates in multiple regression, and hence the chance for false positive research findings, can be drastically inflated when multiple regression models are used to analyze data that contain random measurement error. This article shows the potential for inflated Type I error rates in commonly encountered scenarios and provides new…

Are False-Positive Rates Leading to an Overestimation of Noise-Induced Hearing Loss?

ERIC Educational Resources Information Center

Schlauch, Robert S.; Carney, Edward

2011-01-01

Purpose: To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms. Method: Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center…

False-Positive Cases of Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomographic Scans in Metastasis of Esophageal Cancer

PubMed Central

Yamatsuji, Tomoki; Ishida, Naomasa; Takaoka, Munenori; Hayashi, Jiro; Yoshida, Kazuhiro; Shigemitsu, Kaori; Urakami, Atsushi; Haisa, Minoru; Naomoto, Yoshio

2017-01-01

Of 129 esophagectomies at our institute from June 2010 to March 2015, we experienced three preoperative positron emission tomography-computed tomographic (PET/CT) false positives. Bone metastasis was originally suspected in 2 cases, but they were later found to be bone metastasis negative after a preoperative bone biopsy and clinical course observation. The other cases suspected of mediastinal lymph node metastasis were diagnosed as inflammatory lymphadenopathy by a pathological examination of the removed lymph nodes. Conducting a PET/CT is useful when diagnosing esophageal cancer metastasis, but we need to be aware of the possibility of false positives. Therapeutic decisions should be made based on appropriate and accurate diagnoses, with pathological diagnosis actively introduced if necessary. PMID:28469502

Restricted Boltzmann machines based oversampling and semi-supervised learning for false positive reduction in breast CAD.

PubMed

Cao, Peng; Liu, Xiaoli; Bao, Hang; Yang, Jinzhu; Zhao, Dazhe

2015-01-01

The false-positive reduction (FPR) is a crucial step in the computer aided detection system for the breast. The issues of imbalanced data distribution and the limitation of labeled samples complicate the classification procedure. To overcome these challenges, we propose oversampling and semi-supervised learning methods based on the restricted Boltzmann machines (RBMs) to solve the classification of imbalanced data with a few labeled samples. To evaluate the proposed method, we conducted a comprehensive performance study and compared its results with the commonly used techniques. Experiments on benchmark dataset of DDSM demonstrate the effectiveness of the RBMs based oversampling and semi-supervised learning method in terms of geometric mean (G-mean) for false positive reduction in Breast CAD.

Where Have All the Interactions Gone? Estimating the Coverage of Two-Hybrid Protein Interaction Maps

PubMed Central

Huang, Hailiang; Jedynak, Bruno M; Bader, Joel S

2007-01-01

Yeast two-hybrid screens are an important method for mapping pairwise physical interactions between proteins. The fraction of interactions detected in independent screens can be very small, and an outstanding challenge is to determine the reason for the low overlap. Low overlap can arise from either a high false-discovery rate (interaction sets have low overlap because each set is contaminated by a large number of stochastic false-positive interactions) or a high false-negative rate (interaction sets have low overlap because each misses many true interactions). We extend capture–recapture theory to provide the first unified model for false-positive and false-negative rates for two-hybrid screens. Analysis of yeast, worm, and fly data indicates that 25% to 45% of the reported interactions are likely false positives. Membrane proteins have higher false-discovery rates on average, and signal transduction proteins have lower rates. The overall false-negative rate ranges from 75% for worm to 90% for fly, which arises from a roughly 50% false-negative rate due to statistical undersampling and a 55% to 85% false-negative rate due to proteins that appear to be systematically lost from the assays. Finally, statistical model selection conclusively rejects the Erdös-Rényi network model in favor of the power law model for yeast and the truncated power law for worm and fly degree distributions. Much as genome sequencing coverage estimates were essential for planning the human genome sequencing project, the coverage estimates developed here will be valuable for guiding future proteomic screens. All software and datasets are available in Datasets S1 and S2, Figures S1–S5, and Tables S1−S6, and are also available from our Web site, http://www.baderzone.org. PMID:18039026

The fitting of general force-of-infection models to wildlife disease prevalence data

USGS Publications Warehouse

Heisey, D.M.; Joly, D.O.; Messier, F.

2006-01-01

Researchers and wildlife managers increasingly find themselves in situations where they must deal with infectious wildlife diseases such as chronic wasting disease, brucellosis, tuberculosis, and West Nile virus. Managers are often charged with designing and implementing control strategies, and researchers often seek to determine factors that influence and control the disease process. All of these activities require the ability to measure some indication of a disease's foothold in a population and evaluate factors affecting that foothold. The most common type of data available to managers and researchers is apparent prevalence data. Apparent disease prevalence, the proportion of animals in a sample that are positive for the disease, might seem like a natural measure of disease's foothold, but several properties, in particular, its dependency on age structure and the biasing effects of disease-associated mortality, make it less than ideal. In quantitative epidemiology, the a??force of infection,a?? or infection hazard, is generally the preferred parameter for measuring a disease's foothold, and it can be viewed as the most appropriate way to a??adjusta?? apparent prevalence for age structure. The typical ecology curriculum includes little exposure to quantitative epidemiological concepts such as cumulative incidence, apparent prevalence, and the force of infection. The goal of this paper is to present these basic epidemiological concepts and resulting models in an ecological context and to illustrate how they can be applied to understand and address basic epidemiological questions. We demonstrate a practical approach to solving the heretofore intractable problem of fitting general force-of-infection models to wildlife prevalence data using a generalized regression approach. We apply the procedures to Mycobacterium bovis (bovine tuberculosis) prevalence in bison (Bison bison) in Wood Buffalo National Park, Canada, and demonstrate strong age dependency in the force of infection as well as an increased mortality hazard in positive animals.

Updated paleomagnetic pole from Cretaceous plutonic rocks of the Sierra Nevada, California: Tectonic displacement of the Sierra Nevada block

USGS Publications Warehouse

Hillhouse, John W.; Gromme, Sherman

2011-01-01

We report remanent magnetization measurements from 13 sites in Cretaceous plutonic rocks in the northern Sierra Nevada (38°N–39.5°N). By increasing the number of available paleomagnetic sites, the new data tighten constraints on the displacement history of the Sierra Nevada block and its pre-extensional position relative to interior North America. We collected samples in freshly exposed outcrops along four highway transects. The rocks include diorite, granodiorite, and tonalite with potassium-argon ages (hornblende) ranging from 100 Ma to 83 Ma. By combining our results with previous paleomagnetic determinations from the central and southern Sierra Nevada (excluding sites from the rotated southern tip east of the White Wolf–Kern Canyon fault system), we find a mean paleomagnetic pole of 70.5°N, 188.2°E, A95 = 2.6° (N = 26, Fisher concentration parameter, K = 118). Thermal demagnetization indicates that the characteristic remanence is generally unblocked in a narrow range within 35 °C of the Curie temperature of pure magnetite. Small apparent polar wander during the Cretaceous normal-polarity superchron, plus prolonged acquisition of remanence at the site level, may account for the low dispersion of virtual geomagnetic poles and relatively large K value. Tilt estimates based on overlapping sediments, stream gradients, and thermochronology of the Sierra Nevada plutons vary from 0° to 3° down to the southwest. Without tilt correction, the mean paleomagnetic pole for the Sierra Nevada is essentially coincident with the North American reference pole during the Cretaceous stillstand (125 Ma to 80 Ma). At 95% confidence, the apparent latitude shift is 1.1° ± 3.0° (positive northward), and the apparent rotation is negligible, 0.0° ± 4.7°. Correcting for each degree of tilt, which is limited to 3° on geologic evidence, increases the rotation anomaly 2.2° counterclockwise, while the apparent latitude shift remains unchanged.

False positive fecal coliform in biosolid samples assayed using A-1 medium.

PubMed

Baker, Katherine H; Redmond, Brady; Herson, Diane S

2005-01-01

Two most probable number (MPN) methods-lauryl tryptose broth with Escherichia coli broth confirmation and direct A-1 broth incubation (A-1)--were compared for the enumeration of fecal coliform in lime-treated biosolid. Fecal coliform numbers were significantly higher using the A-1 method. Analysis of positive A-1 tubes, however, indicated that a high percentage of these were false positives. Therefore, the use of A-1 broth for 40 CFR Part 503 Pathogen Reduction (CFR, 1993) compliance testing is not recommended.

Quality control in molecular immunohistochemistry

PubMed Central

2008-01-01

Immunoperoxidase histochemistry is a widespread method of assessing expression of biomolecules in tissue samples. Accurate assessment of the expression levels of genes is critical for the management of disease, particularly as therapy targeted to specific molecules becomes more widespread. Determining the quality of preservation of macromolecules in tissue is important to avoid false negative and false positive results. In this review we discuss (1) issues of sensitivity (false negativity) and specificity (false positivity) of immunohistochemical stains, (2) approaches to better understanding differences in immunostains done by different laboratories (including the recently proposed MISFISHIE specification for tissue localization studies), and (3) approaches to assessing the quality of preservation of macromolecules in tissue, particularly in small biopsy samples. PMID:18648842

The Precautionary Principle and Electric and Magnetic Fields

PubMed Central

Jamieson, Dale; Wartenberg, Daniel

2001-01-01

Current environmental regulation represents a paternalistic policy, more concerned to avoid false positives than false negatives, limiting opportunities for individuals to make choices between risk-avoidance and risk-taking alternatives. For example, many exposures to magnetic fields could be reduced at little or no cost but are not considered seriously, owing to the uncertainty of risk and the concern to avoid false positives. Even though precautionary approaches that focus on avoiding false negatives often do not lead to adverse economic consequences or irrational choices, such approaches usually are not taken. The value of autonomy and the proper role of governmental paternalism with respect to environmental policy need to be considered more carefully in environmental decision making. PMID:11527754

Estimation of position and velocity for a low dynamic vehicle in near space using nonresolved photometric and astrometric data.

PubMed

Jing, Nan; Li, Chuang; Chong, Yaqin

2017-01-20

An estimation method for indirectly observable parameters for a typical low dynamic vehicle (LDV) is presented. The estimation method utilizes apparent magnitude, azimuth angle, and elevation angle to estimate the position and velocity of a typical LDV, such as a high altitude balloon (HAB). In order to validate the accuracy of the estimated parameters gained from an unscented Kalman filter, two sets of experiments are carried out to obtain the nonresolved photometric and astrometric data. In the experiments, a HAB launch is planned; models of the HAB dynamics and kinematics and observation models are built to use as time update and measurement update functions, respectively. When the HAB is launched, a ground-based optoelectronic detector is used to capture the object images, which are processed using aperture photometry technology to obtain the time-varying apparent magnitude of the HAB. Two sets of actual and estimated parameters are given to clearly indicate the parameter differences. Two sets of errors between the actual and estimated parameters are also given to show how the estimated position and velocity differ with respect to the observation time. The similar distribution curve results from the two scenarios, which agree within 3σ, verify that nonresolved photometric and astrometric data can be used to estimate the indirectly observable state parameters (position and velocity) for a typical LDV. This technique can be applied to small and dim space objects in the future.

Influence of ECG measurement accuracy on ECG diagnostic statements.

PubMed

Zywietz, C; Celikag, D; Joseph, G

1996-01-01

Computer analysis of electrocardiograms (ECGs) provides a large amount of ECG measurement data, which may be used for diagnostic classification and storage in ECG databases. Until now, neither error limits for ECG measurements have been specified nor has their influence on diagnostic statements been systematically investigated. An analytical method is presented to estimate the influence of measurement errors on the accuracy of diagnostic ECG statements. Systematic (offset) errors will usually result in an increase of false positive or false negative statements since they cause a shift of the working point on the receiver operating characteristics curve. Measurement error dispersion broadens the distribution function of discriminative measurement parameters and, therefore, usually increases the overlap between discriminative parameters. This results in a flattening of the receiver operating characteristics curve and an increase of false positive and false negative classifications. The method developed has been applied to ECG conduction defect diagnoses by using the proposed International Electrotechnical Commission's interval measurement tolerance limits. These limits appear too large because more than 30% of false positive atrial conduction defect statements and 10-18% of false intraventricular conduction defect statements could be expected due to tolerated measurement errors. To assure long-term usability of ECG measurement databases, it is recommended that systems provide its error tolerance limits obtained on a defined test set.

Sarcoptic-mange detector dogs used to identify infected animals during outbreaks in wildlife

PubMed Central

2012-01-01

Background One of the main aims of forensic investigation is the detection and location of people and substances of interest, such as missing people and illegal drugs. Dogs (Canis lupus var. familiaris) have had an important role in legal and forensic investigations for decades; nonetheless canines’ keen sense of smell has never been utilized in either the surveillance or control of wildlife diseases. The rapid removal and treatment of infected carcasses and/or sick animals is a key task in the management of infectious diseases, but it is usually difficult or impractical to carry out in the wild. Results In this paper we report on a study running over a period of 15 years, in which - for the first time to our knowledge - two disease-detector dogs were trained to follow the scent of Sarcoptes-infected animals and to find carcasses, even under the snow, and apparently no false positives were detected in fieldwork. Sarcoptic mange-detector dogs were used to collect the carcasses of 292 mangy wild animals and to identify, separate from their herd, and capture 63 mange-infected wild animals in the Italian Alps. Conclusions Properly trained disease-detector dogs are an efficient and straightforward tool for surveillance and control of sarcoptic mange in affected wild animal populations. PMID:22776804

Towards a balanced social psychology: causes, consequences, and cures for the problem-seeking approach to social behavior and cognition.

PubMed

Krueger, Joachim I; Funder, David C

2004-06-01

Mainstream social psychology focuses on how people characteristically violate norms of action through social misbehaviors such as conformity with false majority judgments, destructive obedience, and failures to help those in need. Likewise, they are seen to violate norms of reasoning through cognitive errors such as misuse of social information, self-enhancement, and an over-readiness to attribute dispositional characteristics. The causes of this negative research emphasis include the apparent informativeness of norm violation, the status of good behavior and judgment as unconfirmable null hypotheses, and the allure of counter-intuitive findings. The shortcomings of this orientation include frequently erroneous imputations of error, findings of mutually contradictory errors, incoherent interpretations of error, an inability to explain the sources of behavioral or cognitive achievement, and the inhibition of generalized theory. Possible remedies include increased attention to the complete range of behavior and judgmental accomplishment, analytic reforms emphasizing effect sizes and Bayesian inference, and a theoretical paradigm able to account for both the sources of accomplishment and of error. A more balanced social psychology would yield not only a more positive view of human nature, but also an improved understanding of the bases of good behavior and accurate judgment, coherent explanations of occasional lapses, and theoretically grounded suggestions for improvement.

Sarcoptic-mange detector dogs used to identify infected animals during outbreaks in wildlife.

PubMed

Alasaad, Samer; Permunian, Roberto; Gakuya, Francis; Mutinda, Matthew; Soriguer, Ramón C; Rossi, Luca

2012-07-09

One of the main aims of forensic investigation is the detection and location of people and substances of interest, such as missing people and illegal drugs. Dogs (Canis lupus var. familiaris) have had an important role in legal and forensic investigations for decades; nonetheless canines' keen sense of smell has never been utilized in either the surveillance or control of wildlife diseases. The rapid removal and treatment of infected carcasses and/or sick animals is a key task in the management of infectious diseases, but it is usually difficult or impractical to carry out in the wild. In this paper we report on a study running over a period of 15 years, in which - for the first time to our knowledge - two disease-detector dogs were trained to follow the scent of Sarcoptes-infected animals and to find carcasses, even under the snow, and apparently no false positives were detected in fieldwork. Sarcoptic mange-detector dogs were used to collect the carcasses of 292 mangy wild animals and to identify, separate from their herd, and capture 63 mange-infected wild animals in the Italian Alps. Properly trained disease-detector dogs are an efficient and straightforward tool for surveillance and control of sarcoptic mange in affected wild animal populations.

Effect of Linkage Disequilibrium on the Identification of Functional Variants

PubMed Central

Thomas, Alun; Abel, Haley J; Di, Yanming; Faye, Laura L; Jin, Jing; Liu, Jin; Wu, Zheyan; Paterson, Andrew D

2011-01-01

We summarize the contributions of Group 9 of Genetic Analysis Workshop 17. This group addressed the problems of linkage disequilibrium and other longer range forms of allelic association when evaluating the effects of genotypes on phenotypes. Issues raised by long-range associations, whether a result of selection, stratification, possible technical errors, or chance, were less expected but proved to be important. Most contributors focused on regression methods of various types to illustrate problematic issues or to develop adaptations for dealing with high-density genotype assays. Study design was also considered, as was graphical modeling. Although no method emerged as uniformly successful, most succeeded in reducing false-positive results either by considering clusters of loci within genes or by applying smoothing metrics that required results from adjacent loci to be similar. Two unexpected results that questioned our assumptions of what is required to model linkage disequilibrium were observed. The first was that correlations between loci separated by large genetic distances can greatly inflate single-locus test statistics, and, whether the result of selection, stratification, possible technical errors, or chance, these correlations seem overabundant. The second unexpected result was that applying principal components analysis to genome-wide genotype data can apparently control not only for population structure but also for linkage disequilibrium. PMID:22128051

Automatic vetting of planet candidates from ground based surveys: Machine learning with NGTS

NASA Astrophysics Data System (ADS)

Armstrong, David J.; Günther, Maximilian N.; McCormac, James; Smith, Alexis M. S.; Bayliss, Daniel; Bouchy, François; Burleigh, Matthew R.; Casewell, Sarah; Eigmüller, Philipp; Gillen, Edward; Goad, Michael R.; Hodgkin, Simon T.; Jenkins, James S.; Louden, Tom; Metrailler, Lionel; Pollacco, Don; Poppenhaeger, Katja; Queloz, Didier; Raynard, Liam; Rauer, Heike; Udry, Stéphane; Walker, Simon R.; Watson, Christopher A.; West, Richard G.; Wheatley, Peter J.

2018-05-01

State of the art exoplanet transit surveys are producing ever increasing quantities of data. To make the best use of this resource, in detecting interesting planetary systems or in determining accurate planetary population statistics, requires new automated methods. Here we describe a machine learning algorithm that forms an integral part of the pipeline for the NGTS transit survey, demonstrating the efficacy of machine learning in selecting planetary candidates from multi-night ground based survey data. Our method uses a combination of random forests and self-organising-maps to rank planetary candidates, achieving an AUC score of 97.6% in ranking 12368 injected planets against 27496 false positives in the NGTS data. We build on past examples by using injected transit signals to form a training set, a necessary development for applying similar methods to upcoming surveys. We also make the autovet code used to implement the algorithm publicly accessible. autovet is designed to perform machine learned vetting of planetary candidates, and can utilise a variety of methods. The apparent robustness of machine learning techniques, whether on space-based or the qualitatively different ground-based data, highlights their importance to future surveys such as TESS and PLATO and the need to better understand their advantages and pitfalls in an exoplanetary context.

Is breast conservative surgery a reasonable option in multifocal or multicentric tumors?

PubMed Central

Houvenaeghel, Gilles; Tallet, Agnès; Jalaguier-Coudray, Aurélie; Cohen, Monique; Bannier, Marie; Jauffret-Fara, Camille; Lambaudie, Eric

2016-01-01

The incidence of multifocal (MF) and multicentric (MC) carcinomas varies widely among clinical studies, depending on definitions and methods for pathological sampling. Magnetic resonance imaging is increasingly used because it can help identify additional and conventionally occult tumors with high sensitivity. However, false positive lesions might incorrectly influence treatment decisions. Therefore, preoperative biopsies must be performed to avoid unnecessary surgery. Most studies have shown higher lymph node involvement rates in MF/MC tumors than in unifocal tumors. However, the rate of local recurrences is usually low after breast conservative treatment (BCT) of MC/MF tumors. It has been suggested that BCT is a reasonable option for MC/MF tumors in women aged 50-69 years, with small tumors and absence of extensive ductal carcinoma in situ. A meta-analysis showed an apparent decreased overall survival in MC/MF tumors but data are controversial. Surgery should achieve both acceptable cosmetic results and negative margins, which requires thorough preoperative radiological workup and localization of lesions. Boost radiotherapy techniques must be evaluated since double boosts might result in increased toxicity, namely fibrosis. In conclusion, BCT is feasible in selected patients with MC/MF but the choice of surgery must be discussed in a multidisciplinary team comprising at least radiologists, surgeons and radiotherapists. PMID:27081646

Scenes of Aesthetic Education: Ranciere, Oedipus, and "Notre Musique"

ERIC Educational Resources Information Center

De Boever, Arne

2012-01-01

In an interview titled "The Janus-Face of Politicized Art," Jacques Ranciere describes his methodology as follows: "I always try to think in terms of horizontal distributions, combinations between systems of possibilities, not in terms of surface and substratum. Where one searches for the hidden beneath the apparent, a position of…

Midtreatment flare-ups.

PubMed

Harrington, G W; Natkin, E

1992-04-01

It should be apparent that the prompt and effective treatment of midtreatment flare-ups of all types is an essential and integral part of the overall endodontic treatment procedure. The expeditious management of these flare-ups will do much to enhance a positive attitude among patients toward endodontic treatment and to ensure the well-being and comfort of these patients.

Doc Tales

ERIC Educational Resources Information Center

Golden, Larry; Alamia, Jennifer; Baker, Ria; Chilson, Sally; Choucroun, Pierre; Cook, Katrina; de Vries-Kell, Sabina; Marbach, Christina; Peters, Scott

2005-01-01

Acceptance into a doctoral program is personally affirming and gives rise to optimism. It is also true that any change in the life of a person, even an apparently positive one, causes stress. The first cohort of students in a new doctoral program in counseling writes about the impact of embarking on a doctorate on themselves and their significant…

Guidelines to the Development of Human Resources in Libraries: Rationale, Policies, Programs and Recommendations

ERIC Educational Resources Information Center

Library Trends, 1971

1971-01-01

It is apparent that there are many roadblocks preventing the release of the human potential in our libraries. These guidelines take the position that a great deal can be done toward diagnosing and removing these roadblocks by establishing and developing meaningful policies and programs. (49 references) (Author/NH)

The Decline in the Standing of Educational Credentials in Australia.

ERIC Educational Resources Information Center

Marginson, Simon

1995-01-01

An analysis of the economic returns of education in Australia finds a rising need for education at a time of diminishing apparent returns. It is proposed that the notions of credentialism and education as a positional good provide a better explanation for this phenomenon than does the human capital approach. (MSE)

Positioning Civic Engagement on the Higher Education Landscape: Insights from a Civically Engaged Pedagogy

ERIC Educational Resources Information Center

Boland, Josephine Anne

2011-01-01

The significance of competing conceptions of civic engagement is increasingly apparent as efforts are made to respond to the measurement imperative that characterises contemporary higher education. The importance of devising appropriate means of recognising and incentivising civic engagement is asserted in this paper and the potential offered by…

Safety improvement from edge lines on rural two-lane highways (with three-years before and one-year after crash data analysis).

DOT National Transportation Integrated Search

2012-04-01

The previous study Impact of Edge Lines on Safety of Rural Two-Lane Highways completed in 2005 concluded: with edge lines, centralization of vehicles positions is more apparent during night time, which reduces the risk of run-off road (ROR) and he...

Mood Management during the Menstrual Cycle through Selective Exposure to Television.

ERIC Educational Resources Information Center

Weaver, James B., III; Laird, Elizabeth A.

1995-01-01

Finds that women's preferences for comedy television programs were strongest immediately prior to and during menses when negative affect was also most evident. Finds also that at the midpoint of the menstrual cycle, when positive affect proved the strongest, an elevated interest in suspense drama programs was apparent. (SR)

Experimental infection of pregnant goats with swine fever virus.

PubMed

Shimizu, M; Kumagai, T

1989-07-01

Thirteen pregnant goats were inoculated intravenously with the ALD strain of virulent swine fever (SF) virus on Days 64-84 of gestation. Dams showed transient and mild viremia, and produced high serum neutralizing (SN) antibody after inoculation. Six inoculated dams were reared until parturition occurred and bore six apparently normal, one apparently normal but dead, one mummified and three edematous kids. Neutralizing antibody was demonstrated in the pre-colostral sera obtained from all normal kids, but no SF virus was isolated from any of them. The other seven dams were killed on post-inoculation days (PID) 5-61, and fetuses, placenta and amnion were tested for the virus and SN antibody. All fetuses of five dams examined within PID 40 were positive for SF virus, but negative for SN antibody. SF virus was also isolated from one of three fetuses examined on PID 61. Conversely, the other two fetuses examined on PID 61 were negative for SF virus, but positive for SN antibody. Furthermore, SF virus was isolated from the placenta and amnion of all the dams.

Dependency of the apparent contact angle on nonisothermal conditions

NASA Astrophysics Data System (ADS)

Krahl, Rolf; Gerstmann, Jens; Behruzi, Philipp; Bänsch, Eberhard; Dreyer, Michael E.

2008-04-01

The dynamic behavior of liquids in partly filled containers is influenced to a large extend by the angle between the gas-liquid phase boundary and the solid container wall at the contact line. This contact angle in turn is influenced by nonisothermal conditions. In the case of a cold liquid meniscus spreading over a hot solid wall, the contact angle apparently becomes significantly larger. In this paper we want to establish a quantitative equation for this enlargement, both from experimental and numerical data. Our findings can be used to build a subgrid model for computations, where the resolution is not sufficient to resolve the boundary layers. This might be the case for large containers which are exposed to low accelerations and where the contact angle boundary condition determines the position of the free surface. These types of computation are performed, for example, to solve propellant management problems in launcher and satellite tanks. In this application, the knowledge of the position of the free surface is very important for the withdrawal of liquid and the calculation of heat and mass transfer.

Cross-Reactivity of Pantoprazole with Three Commercial Cannabinoids Immunoassays in Urine.

PubMed

Gomila, Isabel; Barceló, Bernardino; Rosell, Antonio; Avella, Sonia; Sahuquillo, Laura; Dastis, Macarena

2017-11-01

Pantoprazole is a frequently prescribed proton pump inhibitor (PPI) commonly utilized in the management of gastrointestinal symptoms. Few substances have proved to cause a false-positive cannabinoid urine screen. However, a case of false-positive urine cannabinoid screen in a patient who received a pantoprazole dose has been recently published. The purpose of this study was to determine the potential cross-reactivity of pantoprazole in the cannabinoid immunoassays: Alere Triage® TOX Drug Screen, KIMS® Cannabinoids II and DRI® Cannabinoids Assay. Drug-free urine to which pantoprazole was added up to 12,000 μg/mL produced negative results in the DRI® Cannabinoids and KIMS® Cannabinoids II. Alere Triage® TOX Drug Screen assay gave positive results at pantoprazole concentrations higher than 1,000 μg/mL. Urine samples from 8 pediatric patients were collected at the beginning of their pantoprazole treatment. Alere Triage® TOX Drug Screen assay produced positive test results in all patient samples and KIMS® Cannabinoids II immunoassay produced positive test results in one patient sample. None patient sample gave a false-positive result when analyzed by the DRI® Cannabinoids Assay. Our findings demonstrate that some cannabinoids immunoassays are susceptible to cross-reaction errors resulting from the presence in urine of pantoprazole and the resulting metabolism of the parent drug. Clinicians should be aware of the possibility of false-positive results for cannabinoids after a pantoprazole treatment. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Zero risk tolerance costs lives: loss of transplantable organs due to human immunodeficiency virus nucleic acid testing of potential donors.

PubMed

Shafer, Teresa J; Schkade, David; Schkade, Lawrence; Geier, Steven S; Orlowski, Jeffrey P; Klintmalm, Goran

2011-09-01

Patients' deaths due to the organ donor shortage make it imperative that every suitable organ be transplanted. False-positive results of tests for infection with the human immunodeficiency virus (HIV) result in lost organs. A survey of US organ procurement organizations collected the numbers of donors and ruled-out potential donors who had a positive result on an HIV test from January 1,2006, to October 31, 2008. Sixty-two percent of US organ procurement organizations participated. Of the 12397 donor/nondonor cases, 56 (0.45%) had an initial positive result on an HIV antibody or HIV nucleic acid test, and only 8 (14.3%) of those were confirmed positive. Of the false-positive results, 50% were from HIV antibody tests and 50% were from HIV nucleic acid tests. Organs are a scarce, finite, and perishable resource. Use of HIV antibody testing has produced a remarkably safe track record of avoiding HIV transmission, with 22 years of nonoccurrence between transmissions. Because false positives occur with any test, including the HIV Ab test, adding nucleic acid testing to the standard donor testing panel doubles the number of false-positive HIV test results and thus the number of medically suitable donors lost. The required HIV antibody test is 99.99% effective in preventing transmission of the HIV virus. Adding the HIV nucleic acid test to routine organ donor screening could result in as many as 761 to 1551 unnecessary deaths of patients between HIV transmission events because medically suitable organs are wasted.

Diagnostic performance of influenza viruses and RSV rapid antigen detection tests in children in tertiary care.

PubMed

Moesker, F M; van Kampen, J J A; Aron, G; Schutten, M; van de Vijver, D A M C; Koopmans, M P G; Osterhaus, A D M E; Fraaij, P L A

2016-06-01

Rapid antigen detection tests (RADTs) are increasingly used to detect influenza viruses and respiratory syncytial virus (RSV). However, their sensitivity and specificity are a matter of debate, challenging their clinical usefulness. Comparing diagnostic performances of BinaxNow Influenza AB(®) (BNI) and BinaxNow RSV(®) (BNR), to those of real-time reverse transcriptase PCR (RT-PCR), virus isolation and direct immunofluorescence (D-IF) in paediatric patients. Between November 2005 and September 2013, 521 nasal washings from symptomatic children (age <5 years) attending our tertiary care centre were tested, with a combination of the respective assays using RT-PCR as gold standard. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of BNI were 69% (confidence interval [CI] [51-83]), 96% [94-97], 55% [39-70] and 98% [96-99] respectively. Of eleven false-negative samples, RT-PCR Ct-values were higher than all RT-PCR positive test results (27 vs 22, p=0.012). Of twenty false-positive samples, none were culture positive and two tested positive in D-IF. Sensitivity, specificity, PPV and NPV for BNR were 79% [73-85], 98% [96-99], 97% [93-99] and 88% [84-91]. Of the 42 false-negative samples the median Ct-value was higher than that of all RT-PCR positive samples (31 vs 23, p<0.0001). Five false-positive samples were detected. Three of these tested positive for RSV in virus isolation and D-IF. RADTs have a high specificity with BNR being superior to BNI. However, their relative low sensitivity limits their usefulness for clinical decision making in a tertiary care paediatric hospital. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Reducing False Positives in Runtime Analysis of Deadlocks

NASA Technical Reports Server (NTRS)

Bensalem, Saddek; Havelund, Klaus; Clancy, Daniel (Technical Monitor)

2002-01-01

This paper presents an improvement of a standard algorithm for detecting dead-lock potentials in multi-threaded programs, in that it reduces the number of false positives. The standard algorithm works as follows. The multi-threaded program under observation is executed, while lock and unlock events are observed. A graph of locks is built, with edges between locks symbolizing locking orders. Any cycle in the graph signifies a potential for a deadlock. The typical standard example is the group of dining philosophers sharing forks. The algorithm is interesting because it can catch deadlock potentials even though no deadlocks occur in the examined trace, and at the same time it scales very well in contrast t o more formal approaches to deadlock detection. The algorithm, however, can yield false positives (as well as false negatives). The extension of the algorithm described in this paper reduces the amount of false positives for three particular cases: when a gate lock protects a cycle, when a single thread introduces a cycle, and when the code segments in different threads that cause the cycle can actually not execute in parallel. The paper formalizes a theory for dynamic deadlock detection and compares it to model checking and static analysis techniques. It furthermore describes an implementation for analyzing Java programs and its application to two case studies: a planetary rover and a space craft altitude control system.

Laxative-free CT colonography

PubMed Central

Slater, A; Betts, M; D'Costa, H

2012-01-01

Objectives The aim of this study was to determine if the introduction of faecal tagging to CT colonography (CTC) made the examination easier to tolerate or reduced the number of false-positives. Methods Our department changed bowel preparation for CT colonography from Picolax (Ferring Pharmaceuticals Ltd, London, UK) to Gastrografin® (Bracco Diagnostics Inc, Princeton, NJ) only with a modified diet. Questionnaires were given to a subgroup of patients within these cohorts. The numbers of false-positives were compared between two cohorts before and after this change. false-positives were defined as lesions reported on CT that were not confirmed by subsequent endoscopic examination. Polyps were matched if they were in the same or adjacent segments, and were within 5 mm of the reported size. Results 412 patients were identified from the Picolax cohort, and 116 from the Gastrografin cohort. 62 patients in each group completed questionnaires. Gastrografin produced less diarrhoea; 34% had five or more bowel motions in the previous day and night, compared with 77% for Picolax (p<0.001), although more patients found drinking it unpleasant compared with Picolax (85% reported drinking Picolax as “easy” vs 61% for Gastrografin; p=0.002). Picolax produced more non-diagnostic examinations, although this difference was not statistically significant. There was not a significant reduction in the numbers of false-positives (2 out of 112 for Gastrografin group, 14 out of 389 for the Picolax group; p=0.54). Conclusion Switching from Picolax to Gastrografin as a CTC preparation technique produced less diarrhoea, but did not reduce the number of false-positives. PMID:22167512

Motivated reconstruction: The effect of brand commitment on false memories.

PubMed

Montgomery, Nicole Votolato; Rajagopal, Priyali

2018-06-01

Across 5 studies, we examine the effect of prior brand commitment on the creation of false memories about product experience after reading online product reviews. We find that brand commitment and the valence of reviews to which consumers are exposed, interact to affect the incidence of false memories. Thus, highly committed consumers are more susceptible to the creation of false experience memories on exposure to positive versus negative reviews, whereas low commitment consumers exhibit similar levels of false memories in response to both positive and negative reviews. Further, these differences across brand commitment are attenuated when respondents are primed with an accuracy motivation, suggesting that the biasing effects of commitment are likely because of the motivation to defend the committed brand. Finally, we find that differences in false memories subsequently lead to differences in intentions to spread word-of-mouth (e.g., recommend the product to friends), suggesting that the consequences of false product experience memories can be significant for marketers and consumers. Our findings contribute to the literatures in false memory and marketing by documenting a motivated bias in false memories because of brand commitment. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Typing of Haemophilus influenzae by Coagglutination and Conventional Slide Agglutination

PubMed Central

Shively, Roxanne G.; Shigel, Janet T.; Peterson, Ellena M.; De La Maza, Luis M.

1981-01-01

Coagglutination was compared with conventional slide agglutination for the typing of 297 clinical isolates of Haemophilus sp. A 100% correlation was found with the H. influenzae type b isolates. Coagglutination showed no false-positive reactions with the nontypable strains of H. influenzae and H. parainfluenzae isolates; however, conventional slide agglutination exhibited many false-positive and non-interpretable reactions. PMID:6977555

Reducing false-positive detections by combining two stage-1 computer-aided mass detection algorithms

NASA Astrophysics Data System (ADS)

Bedard, Noah D.; Sampat, Mehul P.; Stokes, Patrick A.; Markey, Mia K.

2006-03-01

In this paper we present a strategy for reducing the number of false-positives in computer-aided mass detection. Our approach is to only mark "consensus" detections from among the suspicious sites identified by different "stage-1" detection algorithms. By "stage-1" we mean that each of the Computer-aided Detection (CADe) algorithms is designed to operate with high sensitivity, allowing for a large number of false positives. In this study, two mass detection methods were used: (1) Heath and Bowyer's algorithm based on the average fraction under the minimum filter (AFUM) and (2) a low-threshold bi-lateral subtraction algorithm. The two methods were applied separately to a set of images from the Digital Database for Screening Mammography (DDSM) to obtain paired sets of mass candidates. The consensus mass candidates for each image were identified by a logical "and" operation of the two CADe algorithms so as to eliminate regions of suspicion that were not independently identified by both techniques. It was shown that by combining the evidence from the AFUM filter method with that obtained from bi-lateral subtraction, the same sensitivity could be reached with fewer false-positives per image relative to using the AFUM filter alone.

Comparison of bronchoalveolar lavage cytology and transbronchial biopsy in the diagnosis of carcinoma of lung.

PubMed

Ahmed, Ayesha; Ahmed, Sajjad

2004-01-01

The objectives of this study were to compare bronchoalveolar lavage (BAL) cytology and transbronchial biopsy in the diagnosis of carcinoma lung and to determine accuracy of BAL cytology using histopathlologic examination of transbronchial biopsy as gold standard at our center. This study was carried out at Department of Histopathology, Ayub Medical College, Abbottabad, from 1.09.2000 to 28.02.2003. BAL fluid and bronchial biopsy were received and processed simultaneously. Four cytology and a set of histopathology slides were prepared. These were screened and diagnosis recorded. Sensitivity, Specificity, False Positive, False Negative, Positive predictive value and Negative predictive value of BAL cytology were determined using histopathology of transbronchial biopsy as gold standard. We found the sensitivity of BAL cytology to be 93.44% as compared with transbronchial biopsy. The specificity was 100%. There was no false positive while false negative results were 6.55 %. The positive predictive value was 100 %, while the negative predictive value was 75 %. The overall diagnostic efficacy of BAL cytology was 94.52 %. BAL cytology is a highly sensitive and specific test for diagnosis of carcinoma lung. It can be used as a quick and reliable diagnostic method for diagnosis of lung malignancy.

[False positive result in mammography and its association with the presence of obesity: a case-control study].

PubMed

Castro-Ibarra, Marisela; Menchaca-Díaz, Rufino; Cabrales-Ruvalcaba, J Jesús; Luna-V Gómez, Rosa Alicia

2016-01-01

To analyze the association between a false positive result in mammography and obesity, inside the breast cancer early detection program in women affiliated to the Institute of Security and Social Services for Government and Municipality workers of the State of Baja California (ISSSTECALI). A case-control, retrospective study was done in women affiliated to ISSSTECALI to whom a mammography was performed between 2009 and 2012. Women with a false positive result in mammography were included as cases. Controls were women with a true negative result in mammography. Three controls were randomly selected for each case. Obesity was established with the body mass index (BMI) consigned in the woman's clinical file. Age and estrogen replacement therapy were included as co-variables. Seventy nine cases were identified and 237 controls were included. Obesity was observed in 54.4% of cases and in 41.3% of controls (odds ratio: 1.69; 95% confidence interval for odds ratio: 1.01-2.82; p value: 0.043). A logistic regression model including covariables maintained the observed association (p = 0.044). No association was found with analyzed co-variables. A false positive result in mammography was associated with the presence of obesity.

Neural Network Target Identification System for False Alarm Reduction

NASA Technical Reports Server (NTRS)

Ye, David; Edens, Weston; Lu, Thomas T.; Chao, Tien-Hsin

2009-01-01

A multi-stage automated target recognition (ATR) system has been designed to perform computer vision tasks with adequate proficiency in mimicking human vision. The system is able to detect, identify, and track targets of interest. Potential regions of interest (ROIs) are first identified by the detection stage using an Optimum Trade-off Maximum Average Correlation Height (OT-MACH) filter combined with a wavelet transform. False positives are then eliminated by the verification stage using feature extraction methods in conjunction with neural networks. Feature extraction transforms the ROIs using filtering and binning algorithms to create feature vectors. A feed forward back propagation neural network (NN) is then trained to classify each feature vector and remove false positives. This paper discusses the test of the system performance and parameter optimizations process which adapts the system to various targets and datasets. The test results show that the system was successful in substantially reducing the false positive rate when tested on a sonar image dataset.

Estimating False Positive Contamination in Crater Annotations from Citizen Science Data

NASA Astrophysics Data System (ADS)

Tar, P. D.; Bugiolacchi, R.; Thacker, N. A.; Gilmour, J. D.

2017-01-01

Web-based citizen science often involves the classification of image features by large numbers of minimally trained volunteers, such as the identification of lunar impact craters under the Moon Zoo project. Whilst such approaches facilitate the analysis of large image data sets, the inexperience of users and ambiguity in image content can lead to contamination from false positive identifications. We give an approach, using Linear Poisson Models and image template matching, that can quantify levels of false positive contamination in citizen science Moon Zoo crater annotations. Linear Poisson Models are a form of machine learning which supports predictive error modelling and goodness-of-fits, unlike most alternative machine learning methods. The proposed supervised learning system can reduce the variability in crater counts whilst providing predictive error assessments of estimated quantities of remaining true verses false annotations. In an area of research influenced by human subjectivity, the proposed method provides a level of objectivity through the utilisation of image evidence, guided by candidate crater identifications.

The impact of fibre orientation on T1-relaxation and apparent tissue water content in white matter.

PubMed

Schyboll, Felix; Jaekel, Uwe; Weber, Bernd; Neeb, Heiko

2018-02-20

Recent MRI studies have shown that the orientation of nerve fibres relative to the main magnetic field affects the R 2 *(= 1/T 2 *) relaxation rate in white matter (WM) structures. The underlying physical causes have been discussed in several studies but are still not completely understood. However, understanding these effects in detail is of great importance since this might serve as a basis for the development of new diagnostic tools and/or improve quantitative susceptibility mapping techniques. Therefore, in addition to the known angular dependence of R 2 *, the current study investigates the relationship between fibre orientation and the longitudinal relaxation rate, R 1 (= 1/T 1 ), as well as the apparent water content. For a group of 16 healthy subjects, a series of gradient echo, echo-planar and diffusion weighted images were acquired at 3T from which the decay rates, the apparent water content and the diffusion direction were reconstructed. The diffusion weighted data were used to determine the angle between the principle fibre direction and the main magnetic field to examine the angular dependence of R 1 and apparent water content. The obtained results demonstrate that both parameters depend on the fibre orientation and exhibit a positive correlation with the angle between fibre direction and main magnetic field. These observations could be helpful to improve and/or constrain existing biophysical models of brain microstructure by imposing additional constraints resulting from the observed angular dependence R 1 and apparent water content in white matter.

Three-dimensional numerical modeling of full-space transient electromagnetic responses of water in goaf

NASA Astrophysics Data System (ADS)

Chang, Jiang-Hao; Yu, Jing-Cun; Liu, Zhi-Xin

2016-09-01

The full-space transient electromagnetic response of water-filled goaves in coal mines were numerically modeled. Traditional numerical modeling methods cannot be used to simulate the underground full-space transient electromagnetic field. We used multiple transmitting loops instead of the traditional single transmitting loop to load the transmitting loop into Cartesian grids. We improved the method for calculating the z-component of the magnetic field based on the characteristics of full space. Then, we established the fullspace 3D geoelectrical model using geological data for coalmines. In addition, the transient electromagnetic responses of water-filled goaves of variable shape at different locations were simulated by using the finite-difference time-domain (FDTD) method. Moreover, we evaluated the apparent resistivity results. The numerical modeling results suggested that the resistivity differences between the coal seam and its roof and floor greatly affect the distribution of apparent resistivity, resulting in nearly circular contours with the roadway head at the center. The actual distribution of apparent resistivity for different geoelectrical models of water in goaves was consistent with the models. However, when the goaf water was located in one side, a false low-resistivity anomaly would appear on the other side owing to the full-space effect but the response was much weaker. Finally, the modeling results were subsequently confirmed by drilling, suggesting that the proposed method was effective.

29 CFR 825.215 - Equivalent position.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 3 2012-07-01 2012-07-01 false Equivalent position. 825.215 Section 825.215 Labor....215 Equivalent position. (a) Equivalent position. An equivalent position is one that is virtually... responsibilities, which must entail substantially equivalent skill, effort, responsibility, and authority. (b...

29 CFR 825.215 - Equivalent position.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 3 2011-07-01 2011-07-01 false Equivalent position. 825.215 Section 825.215 Labor....215 Equivalent position. (a) Equivalent position. An equivalent position is one that is virtually... responsibilities, which must entail substantially equivalent skill, effort, responsibility, and authority. (b...

29 CFR 825.215 - Equivalent position.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 3 2014-07-01 2014-07-01 false Equivalent position. 825.215 Section 825.215 Labor....215 Equivalent position. (a) Equivalent position. An equivalent position is one that is virtually... responsibilities, which must entail substantially equivalent skill, effort, responsibility, and authority. (b...

29 CFR 825.215 - Equivalent position.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 3 2013-07-01 2013-07-01 false Equivalent position. 825.215 Section 825.215 Labor....215 Equivalent position. (a) Equivalent position. An equivalent position is one that is virtually... responsibilities, which must entail substantially equivalent skill, effort, responsibility, and authority. (b...

29 CFR 825.215 - Equivalent position.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 3 2010-07-01 2010-07-01 false Equivalent position. 825.215 Section 825.215 Labor....215 Equivalent position. (a) Equivalent position. An equivalent position is one that is virtually... responsibilities, which must entail substantially equivalent skill, effort, responsibility, and authority. (b...

Influence of position and length of uterus on implantation and clinical pregnancy rates in IVF and embryo transfer treatment cycles.

PubMed

Egbase, P E; Al-Sharhan, M; Grudzinskas, J G

2000-09-01

In a prospective study of 807 consecutive women shown to have an apparently normal uterus after hysterosalpingography, hysteroscopy or pelvic ultrasonography prior to IVF or intracytoplasmic sperm injection (ICSI) and embryo transfer, the position and length of the uterine cavity was measured routinely at a pre-treatment mock transfer procedure. The apparent length of the uterine cavity was <7 cm in 128 women (group 1), 7-9 cm in 594 women (group 2) and >9 cm in 85 women (group 3). The uterus was noted to be retroverted in 38. 2% (308) women. The embryo transfer catheter was advanced to 5 mm from the uterine fundus based on the previously determined cavity length in all the embryo transfer procedures at 48 h after oocyte collection. Implantation and clinical pregnancy rates were not significantly different with respect to position of the uterus, difficulties encountered in passage of the catheter, mean age of the women, aetiology or duration of infertility or embryology events. An apparently greater cavity length was seen in older and/or parous women, but the difference was not statistically significant. Although the highest implantation and clinical pregnancy rates were seen in women with a cavity length of 7-9 cm (group 2) the differences were not statistically significant: group 1, 18.9 and 36. 7%; group 2, 21.0 and 46.5%; and group 3, 17.3 and 32.9% respectively. The incidence of ectopic pregnancy per reported clinical pregnancy was highest in group 1 women, being 14.9% (7/47) in comparison with group 2 (1.8%, 5/276) and group 3 (0%, 0/27) (P: < 0.0005), suggesting that the size of the uterus is a critical factor in the aetiology of ectopic pregnancy in IVF/ICSI-embryo transfer.

Are overreferrals on developmental screening tests really a problem?

PubMed

Glascoe, F P

2001-01-01

Developmental screening tests, even those meeting standards for screening test accuracy, produce numerous false-positive results for 15% to 30% of children. This is thought to produce unnecessary referrals for diagnostic testing or special services and increase the cost of screening programs. To explore whether children who pass screening tests differ in important ways from those who do not and to determine whether children overreferred for testing benefit from the scrutiny of diagnostic testing and treatment planning. Subjects were a national sample of 512 parents and their children (age range of the children, 7 months to 8 years) who participated in validation studies of various screening tests. Psychological examiners adhering to standardized directions obtained informed consent and administered at least 2 developmental screening measures (the Brigance Screens, the Battelle Developmental Inventory Screening Test, the Denver-II, and the Parents' Evaluations of Developmental Status) and a concurrent battery of diagnostic measures, including tests of intelligence, language, and academic achievement (for children aged 2(1/2) years and older). The performance on diagnostic measures of children who failed screening but were not found to have a disability (false positives) was compared with that of children who passed screening and did not have a disability on diagnostic testing (true negatives). Children with false-positive scores performed significantly (P<.001) lower on diagnostic measures than did children with true-negative scores. The false-positive group had scores in adaptive behavior, language, intelligence, and academic achievement that were 9 to 14 points lower than the scores of those in the true-negative group. When viewing the likelihood of scoring below the 25th percentile on diagnostic measures, children with false-positive scores had a relative risk of 2.6 in adaptive behavior (95% confidence interval [CI], 1.67-4.21), 3.1 in language skills (95% CI, 1.90-5.20), 6.7 on intelligence tests (95% CI, 3.28-13.50), and 4.9 on academic measures (95% CI, 2.61-9.28). Overall, 151 (70%) of the children with false-positive results scored below the 25th percentile on 1 or more diagnostic measures (the point at which most children have difficulty benefiting from typical classroom instruction) in contrast with 64 (29%) of the children with true-negative scores (odds ratio, 5.6; 95% CI, 3.73-8.49). Children with false-positive scores were also more likely to be nonwhite and to have parents who had not graduated from high school. Performance differences between children with true-negative scores and children with false-positive scores continued to be significant (P<.001) even after adjusting for sociodemographic differences between groups. Children overreferred for diagnostic testing by developmental screens perform substantially lower than children with true-negative scores on measures of intelligence, language, and academic achievement-the 3 best predictors of school success. These children also carry more psychosocial risk factors, such as limited parental education and minority status. Thus, children with false-positive screening results are an at-risk group for whom diagnostic testing may not be an unnecessary expense but rather a beneficial and needed service that can help focus intervention efforts. Although such testing will not indicate a need for special education placement, it can be useful in identifying children's needs for other programs known to improve language, cognitive, and academic skills, such as Head Start, Title I services, tutoring, private speech-language therapy, and quality day care.

Some interesting examples of binormal degeneracy and analysis using a contaminated binormal ROC model

NASA Astrophysics Data System (ADS)

Berbaum, Kevin S.; Dorfman, Donald D.

2001-06-01

Receiver operating characteristic (ROC) data with false positive fractions of zero are often difficult to fit with standard ROC methodology, and are sometimes discarded. Some extreme examples of such data were analyzed. A new ROC model is proposed that assumes that for a proportion of abnormalities, no signal information is captured and that those abnormalities have the same distribution as noise along the latent decision axis. Rating reports of fracture for single view ankle radiographs were also analyzed with the binormal ROC model and two proper ROC models. The conventional models gave ROC area close to one, implying a true positive fraction close to one. The data contained no such fractions. When all false positive fractions were zero, conventional ROC areas gave little or no hint of unmistakable differences in true positive fractions. In contrast, the new model can fit ROC data in which some or all of the ROC points have false positive fractions of zero and true positive fractions less than one without concluding perfect performance. These data challenge the validity and robustness of conventional ROC models, but the contaminated binormal model accounts for these data. This research has been published for a different audience.

Arousal-But Not Valence-Reduces False Memories at Retrieval.

PubMed

Mirandola, Chiara; Toffalini, Enrico

2016-01-01

Mood affects both memory accuracy and memory distortions. However, some aspects of this relation are still poorly understood: (1) whether valence and arousal equally affect false memory production, and (2) whether retrieval-related processes matter; the extant literature typically shows that mood influences memory performance when it is induced before encoding, leaving unsolved whether mood induced before retrieval also impacts memory. We examined how negative, positive, and neutral mood induced before retrieval affected inferential false memories and related subjective memory experiences. A recognition-memory paradigm for photographs depicting script-like events was employed. Results showed that individuals in both negative and positive moods-similar in arousal levels-correctly recognized more target events and endorsed fewer false memories (and these errors were linked to remember responses less frequently), compared to individuals in neutral mood. This suggests that arousal (but not valence) predicted memory performance; furthermore, we found that arousal ratings provided by participants were more adequate predictors of memory performance than their actual belonging to either positive, negative or neutral mood groups. These findings suggest that arousal has a primary role in affecting memory, and that mood exerts its power on true and false memory even when induced at retrieval.

Arousal—But Not Valence—Reduces False Memories at Retrieval

PubMed Central

Mirandola, Chiara; Toffalini, Enrico

2016-01-01

Mood affects both memory accuracy and memory distortions. However, some aspects of this relation are still poorly understood: (1) whether valence and arousal equally affect false memory production, and (2) whether retrieval-related processes matter; the extant literature typically shows that mood influences memory performance when it is induced before encoding, leaving unsolved whether mood induced before retrieval also impacts memory. We examined how negative, positive, and neutral mood induced before retrieval affected inferential false memories and related subjective memory experiences. A recognition-memory paradigm for photographs depicting script-like events was employed. Results showed that individuals in both negative and positive moods–similar in arousal levels–correctly recognized more target events and endorsed fewer false memories (and these errors were linked to remember responses less frequently), compared to individuals in neutral mood. This suggests that arousal (but not valence) predicted memory performance; furthermore, we found that arousal ratings provided by participants were more adequate predictors of memory performance than their actual belonging to either positive, negative or neutral mood groups. These findings suggest that arousal has a primary role in affecting memory, and that mood exerts its power on true and false memory even when induced at retrieval. PMID:26938737

Case report of a false positive result of the Xpert® MTB/RIF assay for rifampicin resistance in Mycobacterium tuberculosis complex.

PubMed

Claessens, Jolien; Mathys, Vanessa; Derdelinckx, Inge; Saegeman, Veroniek

2017-06-01

In the present case, we report a false positive result for the detection of rifampicin (RIF) resistance by the Xpert ® MTB/RIF assay, version G4.Miliary Mycobacterium tuberculosis infection (miliary TB) was suspected in a 50-year old Angolan woman. Imaging of the thorax and abdomen displayed diffuse lesions. The Xpert ® MTB/RIF assay conducted on the broncho-alveolar lavage (BAL) fluid was positive for TB and positive for RIF resistance. Confirmatory molecular tests and the phenotypic drug susceptibility determination supported the diagnosis of TB but not RIF resistance. The patient was treated successfully with a conventional therapeutic scheme. Because, the Xpert ® MTB/RIF assay allows the simultaneous detection of TB and RIF resistance, the World Health Organisation (WHO) recommends its use as initial diagnostic test, over microscopy, culture and phenotypic drug susceptibility testing. Even though specificity of the Xpert ® MTB/RIF assay version G4 is high, false positive test results remain possible and have to be considered for the interpretation of the RIF resistance detection by Xpert ® MTB/RIF assay.

Ranitidine interference with standard amphetamine immunoassay.

PubMed

Liu, Li; Wheeler, Sarah E; Rymer, Jacqueline A; Lower, Darla; Zona, Jayne; Peck Palmer, Octavia M; Tamama, Kenichi

2015-01-01

We recently encountered several cases of possible false positive results of amphetamine on the Beckman Coulter AMPH assay, but not on the Siemens EMIT II Plus assay. Our clinical chart review suggested that ranitidine interference may be responsible for the false positive results of the AMPH assays. Blank urine specimens spiked with ranitidine concentrations ranging from 5μg/ml to 5mg/ml were analyzed on both the AMPH and EMIT II Plus assays. To examine if the false positive results were due to assay specific reagent/sample ratios, we prepared 3 different sample to reagent ratios and analyzed them for amphetamine reaction rates on both assays. Ranitidine at 160μg/ml caused a positive interference on the AMPH assay. No interference was observed by ranitidine on the EMIT II Plus assay. Specifically, the sample to reagent ratios tested neither eliminated the positive inference on the AMP assay nor introduced an interference on the EMIT II Plus assay. Unlike the EMIT II Plus assay, the AMPH assay has cross-activity with ranitidine, which is independent of sample to reagent ratio. Copyright © 2014 Elsevier B.V. All rights reserved.

20 CFR 664.430 - What are positive social behaviors?

Code of Federal Regulations, 2010 CFR

2010-04-01

....430 What are positive social behaviors? Positive social behaviors are outcomes of leadership... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false What are positive social behaviors? 664.430... menu of services. Positive social behaviors focus on areas that may include the following: (a) Positive...

20 CFR 664.430 - What are positive social behaviors?

Code of Federal Regulations, 2011 CFR

2011-04-01

....430 What are positive social behaviors? Positive social behaviors are outcomes of leadership... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false What are positive social behaviors? 664.430... menu of services. Positive social behaviors focus on areas that may include the following: (a) Positive...

20 CFR 664.430 - What are positive social behaviors?

Code of Federal Regulations, 2012 CFR

2012-04-01

... 20 Employees' Benefits 4 2012-04-01 2012-04-01 false What are positive social behaviors? 664.430... Parameters § 664.430 What are positive social behaviors? Positive social behaviors are outcomes of leadership... menu of services. Positive social behaviors focus on areas that may include the following: (a) Positive...

20 CFR 664.430 - What are positive social behaviors?

Code of Federal Regulations, 2014 CFR

2014-04-01

... 20 Employees' Benefits 4 2014-04-01 2014-04-01 false What are positive social behaviors? 664.430... Parameters § 664.430 What are positive social behaviors? Positive social behaviors are outcomes of leadership... menu of services. Positive social behaviors focus on areas that may include the following: (a) Positive...

20 CFR 664.430 - What are positive social behaviors?

Code of Federal Regulations, 2013 CFR

2013-04-01

... 20 Employees' Benefits 4 2013-04-01 2013-04-01 false What are positive social behaviors? 664.430... Parameters § 664.430 What are positive social behaviors? Positive social behaviors are outcomes of leadership... menu of services. Positive social behaviors focus on areas that may include the following: (a) Positive...

Preschool children's vision screening in New Zealand: a retrospective evaluation of referral accuracy

PubMed Central

Langeslag-Smith, Miriam A; Vandal, Alain C; Briane, Vincent; Thompson, Benjamin; Anstice, Nicola S

2015-01-01

Objectives To assess the accuracy of preschool vision screening in a large, ethnically diverse, urban population in South Auckland, New Zealand. Design Retrospective longitudinal study. Methods B4 School Check vision screening records (n=5572) were compared with hospital eye department data for children referred from screening due to impaired acuity in one or both eyes who attended a referral appointment (n=556). False positive screens were identified by comparing screening data from the eyes that failed screening with hospital data. Estimation of false negative screening rates relied on data from eyes that passed screening. Data were analysed using logistic regression modelling accounting for the high correlation between results for the two eyes of each child. Primary outcome measure Positive predictive value of the preschool vision screening programme. Results Screening produced high numbers of false positive referrals, resulting in poor positive predictive value (PPV=31%, 95% CI 26% to 38%). High estimated negative predictive value (NPV=92%, 95% CI 88% to 95%) suggested most children with a vision disorder were identified at screening. Relaxing the referral criteria for acuity from worse than 6/9 to worse than 6/12 improved PPV without adversely affecting NPV. Conclusions The B4 School Check generated numerous false positive referrals and consequently had a low PPV. There is scope for reducing costs by altering the visual acuity criterion for referral. PMID:26614622

Ventilation/perfusion single-photon emission computed tomography: a service evaluation.

PubMed

Parekh, Amit; Graham, Richard; Redman, Stewart

2017-08-01

To identify the positive rate and negative predictive value (NPV) of our ventilation/perfusion (V/Q) single-photon emission computed tomography (SPECT) service as respective markers of overcalling (false positives) and undercalling (false negatives). We also identified the indeterminate rate as an indicator of the technical quality of the scans and reporter confidence. V/Q SPECT studies carried out over 5 years were classified into positive, negative and indeterminate results. Patients who had died or had pulmonary emboli on imaging within 3 months of a negative V/Q SPECT were identified as false negatives, from which the NPV was calculated. The total number of positive and indeterminate studies as a proportion of all studies was calculated as the positive and indeterminate rates. The positive rate, NPV and indeterminate rates in nonpregnant patients were 24, 98.7-100 and 3.6%, respectively. The positive rate, NPV and indeterminate rates in pregnant patients were 6.8, 100 and 2.3%, respectively. The positive rate and NPV for nonpregnant patients were similar to the published literature. This suggests that we provide a safe service. The indeterminate rate was slightly higher than the stated guidelines. The study shows that the positive rate and NPV are achievable indicators of potential overcalling and undercalling in a V/Q SPECT service.This is also one of the first studies to report a positive rate in pregnant patients undergoing V/Q SPECT that other institutions can use as a standard when evaluating their services.

Operator Localization of Virtual Objects

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.; Menges, Brian M.; Null, Cynthia H. (Technical Monitor)

1998-01-01

Errors in the localization of nearby virtual objects presented via see-through, helmet mounted displays are examined as a function of viewing conditions and scene content. Monocular, biocular or stereoscopic presentation of the virtual objects, accommodation (required focus), subjects'age, and the position of physical surfaces are examined. Nearby physical surfaces are found to introduce localization errors that differ depending upon the other experimental factors. The apparent physical size and transparency of the virtual objects and physical surfaces respectively are also influenced by their relative position when superimposed. Design implications are discussed.

Astronaut James Lovell at his position in the Lunar Module

NASA Image and Video Library

1970-04-14

AS13-59-8484 (April 1970) --- Astronaut James A. Lovell Jr., commander, is pictured at his position in the Lunar Module (LM). The Apollo 13 crew of astronauts Lovell; John L. Swigert Jr., command module pilot; and Fred W. Haise Jr., lunar module pilot, relied on the LM as a "lifeboat". The dependence on the LM was caused by an apparent explosion of oxygen tank number two in the Service Module (SM). The LM was jettisoned just prior to Earth re-entry by the Command Module (CM).

About the Modeling of Radio Source Time Series as Linear Splines

NASA Astrophysics Data System (ADS)

Karbon, Maria; Heinkelmann, Robert; Mora-Diaz, Julian; Xu, Minghui; Nilsson, Tobias; Schuh, Harald

2016-12-01

Many of the time series of radio sources observed in geodetic VLBI show variations, caused mainly by changes in source structure. However, until now it has been common practice to consider source positions as invariant, or to exclude known misbehaving sources from the datum conditions. This may lead to a degradation of the estimated parameters, as unmodeled apparent source position variations can propagate to the other parameters through the least squares adjustment. In this paper we will introduce an automated algorithm capable of parameterizing the radio source coordinates as linear splines.

Description of a bacterium associated with redmouth disease of rainbow trout (Salmo gairdneri)

USGS Publications Warehouse

Ross, A.J.; Rucker, R.R.; Ewing, W.H.

1966-01-01

A description was given of a gram-negative, peritrichously flagellated, fermentative bacterium that was isolated on numerous occasions from kidney tissues of rainbow trout (Salmo gairdneri) afflicted with redmouth disease. Although the bacteria apparently were members of the family Enterobacteriaceae, it was impossible to determine their taxonomic position within the family with certainty. Hence it was recommended that their taxonomic position remain sub judice for the present. As a temporary designation RM bacterium was used. Redmouth disease was transmitted from infected to normal fish through the medium of water.

(2E)-1-(2,6-Dichloro-3-fluoro-phen-yl)-3-phenyl-prop-2-en-1-one.

PubMed

Praveen, Aletti S; Yathirajan, Hemmige S; Narayana, Badiadka; Gerber, Thomas; Hosten, Eric; Betz, Richard

2012-04-01

In the title compound, C(15)H(9)Cl(2)FO, the F atom shows positional disorder over two positions, with site-occupancy factors of 0.747 (4) and 0.253 (4). The dihedral angle between the rings is 86.37 (10)°. In the crystal, C-H⋯O contacts connect the mol-ecules into chains along the c axis. The shortest inter-centroid distance between two aromatic systems is 3.6686 (12) Å and is apparent between the halogenated rings.

Does disseminated nontuberculous mycobacterial disease cause false-positive Determine B-LAM lateral flow assay results? A retrospective review.

PubMed

Nel, Jeremy S; Lippincott, Christopher K; Berhanu, Rebecca; Spencer, David C; Sanne, Ian M; Ive, Prudence

2017-06-02

We retrospectively reviewed the Determine TB-LAM lateral flow assay (LF-LAM) results among HIV-infected patients with disseminated nontuberculous mycobacterial (NTM) disease. LF-LAM was positive in 19/21 patients without evidence of tuberculosis coinfection. Although tuberculosis-NTM coinfection may have been underdiagnosed, our results suggest that disseminated NTM disease may cause false-positive LF-LAM results. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

False-negative rapid diagnostic tests for malaria and deletion of the histidine-rich repeat region of the hrp2 gene.

PubMed

Koita, Ousmane A; Doumbo, Ogobara K; Ouattara, Amed; Tall, Lalla K; Konaré, Aoua; Diakité, Mahamadou; Diallo, Mouctar; Sagara, Issaka; Masinde, Godfred L; Doumbo, Safiatou N; Dolo, Amagana; Tounkara, Anatole; Traoré, Issa; Krogstad, Donald J

2012-02-01

We identified 480 persons with positive thick smears for asexual Plasmodium falciparum parasites, of whom 454 had positive rapid diagnostic tests (RDTs) for the histidine-rich protein 2 (HRP2) product of the hrp2 gene and 26 had negative tests. Polymerase chain reaction (PCR) amplification for the histidine-rich repeat region of that gene was negative in one-half (10/22) of false-negative specimens available, consistent with spontaneous deletion. False-negative RDTs were found only in persons with asymptomatic infections, and multiplicities of infection (MOIs) were lower in persons with false-negative RDTs (both P < 0.001). These results show that parasites that fail to produce HRP2 can cause patent bloodstream infections and false-negative RDT results. The importance of these observations is likely to increase as malaria control improves, because lower MOIs are associated with false-negative RDTs and false-negative RDTs are more frequent in persons with asymptomatic infections. These findings suggest that the use of HRP2-based RDTs should be reconsidered.

Intellectual factors in false memories of patients with schizophrenia.

PubMed

Zhu, Bi; Chen, Chuansheng; Loftus, Elizabeth F; Dong, Qi; Lin, Chongde; Li, Jun

2018-07-01

The current study explored the intellectual factors in false memories of 139 patients with schizophrenia, using a recognition task and an IQ test. The full-scale IQ score of the participants ranged from 57 to 144 (M = 100, SD = 14). The full IQ score had a negative correlation with false recognition in patients with schizophrenia, and positive correlations with high-confidence true recognition and discrimination rates. Further analyses with the subtests' scores revealed that false recognition was negatively correlated with scores of performance IQ (and one of its subtests: picture arrangement), whereas true recognition was positively correlated with scores of verbal IQ (and two of its subtests: information and digit span). High-IQ patients had less false recognition (overall or high-confidence false recognition), more high-confidence true recognition, and higher discrimination abilities than those with low IQ. These findings contribute to a better understanding of the cognitive mechanism in false memory of patients with schizophrenia, and are of practical relevance to the evaluation of memory reliability in patients with different intellectual levels. Copyright © 2018 Elsevier B.V. All rights reserved.

Apparent mass matrix of standing subjects exposed to multi-axial whole-body vibration.

PubMed

Tarabini, Marco; Solbiati, Stefano; Saggin, Bortolino; Scaccabarozzi, Diego

2016-08-01

This paper describes the experimental characterisation of the apparent mass matrix of eight male subjects in standing position and the identification of nonlinearities under both mono-axial and dual-axis whole-body vibration. The nonlinear behaviour of the response was studied using the conditioned response techniques considering models of increasing complexity. Results showed that the cross-axis terms are comparable to the diagonal terms. The contribution of the nonlinear effects are minor and can be endorsed to the change of modal parameters during the tests. The nonlinearity generated by the vibration magnitude is more evident in the subject response, since magnitude-dependent effects in the population are overlaid by the scatter in the subjects' biometric data. The biodynamic response is influenced by the addition of a secondary vibration axis and, in case of dual-axis vibrations, the overall magnitude has a marginal contribution. Practitioner Summary: We have measured both the diagonal and cross-axis elements of the apparent mass matrix. The effect of nonlinearities and the simultaneous presence of vibration along two axes are smaller than the inter-subject variability.

Temperature dependence of internal friction in enzyme reactions.

PubMed

Rauscher, Anna Á; Simon, Zoltán; Szöllosi, Gergely J; Gráf, László; Derényi, Imre; Malnasi-Csizmadia, Andras

2011-08-01

Our aim was to elucidate the physical background of internal friction of enzyme reactions by investigating the temperature dependence of internal viscosity. By rapid transient kinetic methods, we directly measured the rate constant of trypsin 4 activation, which is an interdomain conformational rearrangement, as a function of temperature and solvent viscosity. We found that the apparent internal viscosity shows an Arrhenius-like temperature dependence, which can be characterized by the activation energy of internal friction. Glycine and alanine mutations were introduced at a single position of the hinge of the interdomain region to evaluate how the flexibility of the hinge affects internal friction. We found that the apparent activation energies of the conformational change and the internal friction are interconvertible parameters depending on the protein flexibility. The more flexible a protein was, the greater proportion of the total activation energy of the reaction was observed as the apparent activation energy of internal friction. Based on the coupling of the internal and external movements of the protein during its conformational change, we constructed a model that quantitatively relates activation energy, internal friction, and protein flexibility.

Landscape of Familial Isolated and Young-Onset Pituitary Adenomas: Prospective Diagnosis in AIP Mutation Carriers

PubMed Central

Hernández-Ramírez, Laura C.; Gabrovska, Plamena; Dénes, Judit; Stals, Karen; Trivellin, Giampaolo; Tilley, Daniel; Ferraù, Francesco; Evanson, Jane; Ellard, Sian; Grossman, Ashley B.; Roncaroli, Federico; Gadelha, Mônica R.

2015-01-01

Context: Familial isolated pituitary adenoma (FIPA) due to aryl hydrocarbon receptor interacting protein (AIP) gene mutations is an autosomal dominant disease with incomplete penetrance. Clinical screening of apparently unaffected AIP mutation (AIPmut) carriers could identify previously unrecognized disease. Objective: To determine the AIP mutational status of FIPA and young pituitary adenoma patients, analyzing their clinical characteristics, and to perform clinical screening of apparently unaffected AIPmut carrier family members. Design: This was an observational, longitudinal study conducted over 7 years. Setting: International collaborative study conducted at referral centers for pituitary diseases. Participants: FIPA families (n = 216) and sporadic young-onset (≤30 y) pituitary adenoma patients (n = 404) participated in the study. Interventions: We performed genetic screening of patients for AIPmuts, clinical assessment of their family members, and genetic screening for somatic GNAS1 mutations and the germline FGFR4 p.G388R variant. Main Outcome Measure(s): We assessed clinical disease in mutation carriers, comparison of characteristics of AIPmut positive and negative patients, results of GNAS1, and FGFR4 analysis. Results: Thirty-seven FIPA families and 34 sporadic patients had AIPmuts. Patients with truncating AIPmuts had a younger age at disease onset and diagnosis, compared with patients with nontruncating AIPmuts. Somatic GNAS1 mutations were absent in tumors from AIPmut-positive patients, and the studied FGFR4 variant did not modify the disease behavior or penetrance in AIPmut-positive individuals. A total of 164 AIPmut-positive unaffected family members were identified; pituitary disease was detected in 18 of those who underwent clinical screening. Conclusions: A quarter of the AIPmut carriers screened were diagnosed with pituitary disease, justifying this screening and suggesting a variable clinical course for AIPmut-positive pituitary adenomas. PMID:26186299

Divergent effects of different positive emotions on moral judgment.

PubMed

Strohminger, Nina; Lewis, Richard L; Meyer, David E

2011-05-01

Positive emotions are often treated as relatively similar in their cognitive-behavioral effects, and as having unambiguously beneficial consequences. For example, Valdesolo and DeSteno (2006) reported that a humorous video made people more prone to choose a utilitarian solution to a moral dilemma. They attributed this finding to increased positive affect. To determine whether such results actually stem in general from positive affect or from other more specific properties of humor, we conducted an experiment with moral dilemmas presented during an interleaved emotion-induction procedure involving mirth and another positive emotion, elevation. Mirth increased permissiveness for deontological violations, whereas elevation had the opposite effect. Furthermore, affective valence had no apparent independent influence on these judgments. Our results suggest that mirth and elevation have distinct cognitive consequences whose properties reflect their respective social functions, not their shared positive valence. Copyright © 2010 Elsevier B.V. All rights reserved.