scholarly journals Effects of Obstructions on the Accuracy of Bluetooth Contact Tracing

2020 ◽  
Author(s):  
David Labrique
Keyword(s):  
Human Body ◽  
False Positive ◽  
False Negative ◽  
Signal Strength ◽  
Contact Tracing ◽  
Raspberry Pi ◽  
Distance Estimate ◽  
Calculated Distance ◽  
False Positives And Negatives

During the COVID-19 pandemic, the idea of facilitating contact tracing using Bluetooth is becoming widespread due to the prevalence of smartphones. The automatic classification of encounters between smartphones is challenging due to variations in signal strength – resulting in high false positive and false negative rates. For example, obstructions between two smartphones can reduce the strength of received signals and thus increase the calculated distance. This can benefit contact tracing by preventing a contact from being added to the database when people are on opposite side of a wall, but can also harm tracing efforts if two people are close together but their bodies reduce the signal between devices. A Raspberry Pi Bluetooth emitter and a phone receiver were placed 1 meter apart, and various obstacles were placed between them to simulate normal obstacles. Drywall and stud walls were shown to be ineffective at reducing Bluetooth signal strength. Cinder block, and especially the human body, were found to effectively lower Bluetooth strength so that the distance estimate was higher. The results of these experiments imply Bluetooth contact tracing will involve many false positives and negatives.

scholarly journals The diagnostic efficiency of some serological tests for bovine brucellosis

1978 ◽  
Vol 80 (3) ◽  
pp. 373-384 ◽  
Author(s):  
R. J. Chappel ◽  
D. J. McNaught ◽  
J. A. Bourke ◽  
G. S. Allan
Keyword(s):  
False Positive ◽  
False Negative ◽  
Diagnostic System ◽  
Diagnostic Value ◽  
Diagnostic Efficiency ◽  
Bovine Brucellosis ◽  
Serological Tests ◽  
Probable Infection ◽  
Serum Agglutination

SummaryResults obtained from 1887 sera using three serological tests for bovine brucellosis were compared with a serological classification of sera described as the ‘probable infection status’. Sera showing apparent false positive and apparent false negative reactions were identified, and were subjected to supplementary testing as appropriate.The serum agglutination test (SAT) gave 35% apparent false negative reactions and 5% apparent false positives. The complement fixation test (CFT) gave 12% apparent false negative reactions using warm fixation (CFTW) and at least 5% using cold fixation (CFTC). The routine diagnostic system used in Victoria, in which the CFTW is supplemented by the CFTC and the SAT, gave 9% apparent false negative reactions and 2% apparent false positive reactions. The radioimmunoassay gave 1% or 6% apparent false negative reactions, depending the minimum diagnostic value used.Atypical reactions in the CFT sometimes caused difficulties in diagnosis.

scholarly journals The false classification of extinction risk in noisy environments

2014 ◽  
Vol 281 (1787) ◽  
pp. 20132935 ◽  
Author(s):  
B. M. Connors ◽  
A. B. Cooper ◽  
R. M. Peterman ◽  
N. K. Dulvy
Keyword(s):  
False Positive ◽  
Extinction Risk ◽  
False Negative ◽  
False Alarms ◽  
Observation Error ◽  
Noisy Environments ◽  
Stochastic Variation ◽  
Process Noise ◽  
Autocorrelated Process

Abundance trends are the basis for many classifications of threat and recovery status, but they can be a challenge to interpret because of observation error, stochastic variation in abundance (process noise) and temporal autocorrelation in that process noise. To measure the frequency of incorrectly detecting a decline (false-positive or false alarm) and failing to detect a true decline (false-negative), we simulated stable and declining abundance time series across several magnitudes of observation error and autocorrelated process noise. We then empirically estimated the magnitude of observation error and autocorrelated process noise across a broad range of taxa and mapped these estimates onto the simulated parameter space. Based on the taxa we examined, at low classification thresholds (30% decline in abundance) and short observation windows (10 years), false alarms would be expected to occur, on average, about 40% of the time assuming density-independent dynamics, whereas false-negatives would be expected to occur about 60% of the time. However, false alarms and failures to detect true declines were reduced at higher classification thresholds (50% or 80% declines), longer observation windows (20, 40, 60 years), and assuming density-dependent dynamics. The lowest false-positive and false-negative rates are likely to occur for large-bodied, long-lived animal species.

scholarly journals One Ringgit and Five Ringgit Malaysian Banknotes Reader Using Backlight Mechanism and Image Processing Techniques

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 1098
Author(s):  
Turki Khaled Salem ◽  
Wai Kit Wong ◽  
Thu Soe Min ◽  
Eng Kiong Wong
Keyword(s):  
Image Processing ◽  
False Positive ◽  
Visually Impaired ◽  
Confusion Matrix ◽  
False Negative ◽  
Experimental Result ◽  
Raspberry Pi ◽  
Image Processing Techniques ◽  
Processing Techniques ◽  
Visually Impaired Persons

Visually impaired persons face challenges in running business activities, especially in handling banknotes. Malaysia researchers had proposed some Ringgit banknotes recognition systems to aid visually impaired persons recognize and classify Ringgit banknotes. However, these electronic banknote readers can only recognize Malaysian Banknotes’ Ringgit value, they have no counterfeit detection features. The purpose of this study is to develop a banknote reader that not only can help visually impaired persons recognize the banknote value, but also to detect the counterfeit of the banknote, safeguarding their losses. This paper proposed a Malaysian banknote reader using backlight mechanism and image processing techniques to read and detect counterfeit for one Ringgit and five Ringgit Malaysian banknotes. The developed handheld banknote reader used visual type sensor to capture banknote image, passed to raspberry pi controller to perform image processing on banknote value and the extracted watermarks features. The developed image processing algorithm will trace out the region of interests: 1)see-thru windows, 2)Crescent and Star, 3)Perfect see though register and detect the watermarks features accordingly. The processed result will be passed back to the handheld banknote reader and broadcast on an attached mini speaker to aid the visually impaired understand the holding banknote, whether it is a real one Ringgit, real five Ringgit or none of them. The experimental result shown by this approach able to accomplish numerous round of banknote reading attempts with successful outcomes. Confusion matrix is further employed to study the performance of the banknote reader, in terms of true positive, true negative, false positive and false negative. Details analysis had been focused on the critical false positive cases (predicted real banknote and actually is fake banknote) and false negative cases (predicted fake banknote and it is actually real banknote).

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Matrix metalloproteinases: structure, functions and genetic polymorphism

2017 ◽  
pp. 14-23
Author(s):  
А.С. Шадрина ◽  
И.В. Терешкина ◽  
Я.З. Плиева ◽  
Д.Н. Кушлинский ◽  
Д.О. Уткин ◽  
...  
Keyword(s):  
Genetic Polymorphism ◽  
Matrix Metalloproteinases ◽  
Active Center ◽  
Human Body ◽  
Enzymatic Catalysis ◽  
Structure Functions ◽  
Zinc Ion ◽  
Etiological Factors ◽  
Mmp Genes

Матриксные металлопротеиназы (ММП) - ферменты класса гидролаз, осуществляющие ферментативный катализ с помощью связанного в активном центре иона цинка. Функции ММП разнообразны, и нарушение баланса их активности может быть одним из этиологических факторов различных заболеваний. В данном обзоре рассмотрена классификация ММП человека, особенности их структуры и регуляции, а также роль в физиологических и патологических процессах в организме человека. Приведен перечень наиболее изученных на настоящий момент полиморфных вариантов генов MMП, описаны их функциональные эффекты и представлены результаты ассоциативных исследований. Matrix metalloproteinases (MMPs) are enzymes of the hydrolase class that carry out enzymatic catalysis with the help of a zinc ion bound in the active center. MMP functions are diverse, and a disturbance in the balance of their activity may be one of the etiological factors of various diseases. In this review, the classification of human MMP, the features of their structure and regulation, as well as the role in physiological and pathological processes in the human body are considered. A list of the most studied polymorphic versions of MMP genes has been given, their functional effects have been described, and the results of associative studies have been presented.

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