Accuracy and completeness of a near real-time citizen science-based multi-disaster inventory in the Rwenzori Mountains, Uganda

2021 ◽  
Author(s):  
John Sekajugo ◽  
Grace R Kagoro ◽  
Liesbet Jacobs ◽  
Clovis Kabaseke ◽  
Esther Namara ◽  
...  
Keyword(s):  
Real Time ◽  
Citizen Science ◽  
Satellite Imagery ◽  
News Media ◽  
Satellite Image ◽  
False Positives ◽  
Small Scale ◽  
False Negatives ◽  
Rwenzori Mountains ◽  
Systematic Field

<p>Accurate and complete inventory of natural hazard occurrence and their level of impact is a key first step to risk assessment, but it remains a challenge, especially for high frequency low impact events that rarely makes it to the news media. This challenge is even greater in rural areas of developing countries such as Uganda, where limited IT facilities prevent dissemination of information through social media. Here we report on a citizen-science initiative to monitor small-scale disasters (landslides and floods) occurring in the Rwenzori Mountains. A network of citizen (geo-)observers was established in February 2017 to collect temporally explicit geo-referenced information on eight different hazards and their impact using smartphone technology. Since then, over 500 hazard occurrences have been reported. However, such dataset needs to be assessed for its accuracy and potential biases before being used for scientific analysis. In this study, we evaluate the accuracy and completeness of the geo-observer-based disaster reports. First, systematic errors are reduced by peer reviewing the reports and implementing automatic tests to assess potential errors in detection and biases. Then, we compare the geo-observer-based records with two independent inventories collected through systematic field mapping and  satellite imagery mapping, focusing on landslide and flood events for the period between May 2019 and May 2020.  Results show over 95% of the geo-observer reports validated in the field were correctly identified and recorded less than 5 days after the occurrence (60% true positives, 1% false positives and 39% false negatives). For the satellite imagery mapping, 29% were true positives, 43% false positives and 28% false negatives. Geo-observers provide near real time disaster information on the location and level of impact, something difficult to achieve with systematic field and satellite imagery mapping. Depending on the topography of the area and the weather conditions, it can take several days to weeks before a cloud-free satellite image of a place can be obtained. The false negatives in the Geo-observer data are due to the tendency to report mainly occurrences along roads and rural foot paths since such occurrences are easily seen and accessed. Isolated small and inaccessible landslides are often not seen or reported to the Geo-observers. While satellite imagery mapping provides an opportunity to record disaster occurrences even in extremely inaccessible places, small landslides are often missed while shallow ones can easily be confused with freshly cleared vegetation for crop planting. Citizen science-based disaster reporting therefore not only provide the spatial occurrence of disasters but also the temporal and weather-related information, necessary for disaster risk analysis.</p>

Sky Segmentation for Enhanced Depth Reconstruction and Bokeh Rendering with Efficient Architectures

2020 ◽  
Vol 2020 (14) ◽  
pp. 378-1-378-7
Author(s):  
Tyler Nuanes ◽  
Matt Elsey ◽  
Radek Grzeszczuk ◽  
John Paul Shen
Keyword(s):  
Real Time ◽  
Mobile Device ◽  
Computational Cost ◽  
False Positives ◽  
Compact Model ◽  
High Quality ◽  
False Negatives ◽  
Trade Off ◽  
Depth Reconstruction ◽  
Binary Classifiers

We present a high-quality sky segmentation model for depth refinement and investigate residual architecture performance to inform optimally shrinking the network. We describe a model that runs in near real-time on mobile device, present a new, highquality dataset, and detail a unique weighing to trade off false positives and false negatives in binary classifiers. We show how the optimizations improve bokeh rendering by correcting stereo depth misprediction in sky regions. We detail techniques used to preserve edges, reject false positives, and ensure generalization to the diversity of sky scenes. Finally, we present a compact model and compare performance of four popular residual architectures (ShuffleNet, MobileNetV2, Resnet-101, and Resnet-34-like) at constant computational cost.

An Evaluation of Conventional Culture, invA PCR, and the Real-Time PCR iQ-Check Kit as Detection Tools for Salmonella in Naturally Contaminated Premarket and Retail Turkey

2008 ◽  
Vol 71 (2) ◽  
pp. 386-391 ◽  
Author(s):  
CHANTAL W. NDE ◽  
MOHAMED K. FAKHR ◽  
CURT DOETKOTT ◽  
CATHERINE M. LOGUE
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Culture Method ◽  
False Positives ◽  
Poultry Meat ◽  
Processing Plant ◽  
False Negatives ◽  
Conventional Culture ◽  
Total Agreement ◽  
Conventional Culture Method

This study was aimed at comparing the ability of conventional culture, the iQ-Check real-time PCR kit, and invA PCR to detect Salmonella in naturally contaminated premarket and retail turkey parts. Premarket (n = 120) turkey parts collected from a commercial turkey processing plant, and retail turkey parts (n = 138) were examined. Both PCR methods detected a significantly greater (P < 0.05) number of positive samples when compared with the conventional culture method for the premarket turkey parts. The indices of total agreement between the conventional culture method and the iQ-Check kit for the premarket and retail parts were 79.2% (95% CI: 70.8, 86) and 90.6% (95% CI: 84.4, 94.9), respectively. When the conventional culture method was compared with invA PCR for Salmonella detection in the premarket and retail parts, the indices of total agreement were 75.8% (95% CI: 67.2, 83.2) and 84.1% (95% CI: 76.9, 89.7), respectively. The rates of false positives (premarket: 31.9%, retail: 9.7%) and false negatives (premarket: 5.9%, retail: 9.7%) were determined between the culture method and the iQ-Check kit. When invA PCR was compared with the culture method, the rates of false positives (premarket: 37.7%, retail: 11.1%) and false negatives (premarket: 5.9%, retail: 18.3%) were obtained. The higher total agreement and the lower rates of both false positives and false negatives for the iQ-Check kit compared with invA PCR for both premarket and retail turkey parts corroborates the use of the iQ-Check kit as a screening tool for Salmonella in poultry meat.

Supporting a drinking water contaminant warning system using the adenosine triphosphate test

2010 ◽  
Vol 37 (11) ◽  
pp. 1423-1431 ◽  
Author(s):  
Mirnader Ghazali ◽  
Edward A. McBean ◽  
Pat Whalen ◽  
Kelvin Journal
Keyword(s):  
Drinking Water ◽  
Real Time ◽  
Adenosine Triphosphate ◽  
Warning System ◽  
False Positives ◽  
False Negatives ◽  
Biological Contamination ◽  
Water Contaminant ◽  
Tier System ◽  
Confirmatory Analysis

A contaminant warning system (CWS) with the capability to detect aberrations in drinking water in real-time or near real-time represents significant value for protection of consumers from accidental or intentional contamination of drinking water. The capabilities of a two-tier CWS are examined, the first including nonpurgeable organic carbon (NPOC), free chlorine, turbidity, pH, and conductivity, followed by a confirmatory adenosine triphosphate (ATP) analysis, to control false positives. The utility of the confirmatory analysis is improved by use of a continuous ultrafiltration system, which improves the detection and the correlation between the concentration of Escherichia coli in the sample and measured ATP. The sample was concentrated one hundredfold in 22 min increasing the ATP value of the sample from 980 to 9.8 × 104 CFU/mL as microbial equivalents. The two-tier system is shown to be a successful method for confirmation of biological contamination in near real-time, while controlling false positives and (or) false negatives.

scholarly journals Automatic identification of magnetic clouds and cloud-like regions at 1 AU: occurrence rate and other properties

2005 ◽  
Vol 23 (7) ◽  
pp. 2687-2704 ◽  
Author(s):  
R. P. Lepping ◽  
C.-C. Wu ◽  
D. B. Berdichevsky
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Real Time ◽  
False Positives ◽  
Large Percentage ◽  
Occurrence Rate ◽  
Small Scale ◽  
Automatic Identification ◽  
Interplanetary Magnetic Fields ◽  
Interplanetary Physics

Abstract. A scheme is presented whose purpose is twofold: (1) to enable the automatic identification of an interplanetary magnetic cloud (MC) passing Earth from real-time measurements of solar wind magnetic field and plasma quantities or (2) for on-ground post-data collection MC identification ("detection" mode). In the real-time ("prediction") mode the scheme should be applicable to data from a spacecraft upstream of Earth, such as ACE, or to that of any near real-time field and plasma monitoring platform in the solar wind at/near 1AU. The initial identification of a candidate MC-complex is carried out by examining proton plasma beta, degree of small-scale smoothness of the magnetic field's directional change, duration of a candidate structure, thermal speed, and field strength. In a final stage, there is a test for large-scale B-field smoothness within the candidate regions that were identified in the first stage. The scheme was applied to WIND data over the period 1995 through mid-August of 2003 (i.e. over 8.6 years), in order to determine its effectiveness in identifying MC passages of any type (i.e. NS, SN, all S, all N, etc. types). (NS refers to the B component of the magnetic field going from north (+) to south (-) in GSE coordinates.) The distribution of these MC types for WIND is provided. The results of the scheme are compared to WIND MCs previously identified by visual inspection (called MFI MCs) with relatively good agreement, in the sense of capturing a large percentage of MFI MCs, but at the expense of finding a large percentage of "false positives". The scheme is shown to be able to find some previously ignored MCs among the false positives. It should be effective in helping to identify in real time most NS MCs for magnetic storm forecasting. The NS type of MC is expected to be most prevalent in solar cycle 24, which should start around 2007. The scheme is likely to be applicable to solar wind measurements taken well within 1 AU to well beyond it. Keywords. Interplanetary physics (Interplanetary magnetic fields; Solar wind plasma) – Magnetospheric physics (Solar wind-magnetosphere interactions)

Automatic Extraction of Acronyms from Text

2020 ◽  
Author(s):  
Stuart Yeates
Keyword(s):  
Digital Library ◽  
False Positives ◽  
Automatic Extraction ◽  
False Negatives ◽  
Library Research ◽  
Communications Theory ◽  
Textual Content

A brief introduction to acronyms is given and motivation for extracting them in a digital library environment is discussed. A technique for extracting acronyms is given with an analysis of the results. The technique is found to have a low number of false negatives and a high number of false positives. Introduction Digital library research seeks to build tools to enable access of content, while making as few as possible assumptions about the content, since assumptions limit the range of applicability of the tools. Generally, the broader the assumptions the more widely applicable the tools. For example, keyword based indexing [5] is based on communications theory and applies to all natural human textual languages (allowances for differences in character sets and similar localisation issues not withstanding) . The algorithm described in this paper makes much stronger assumptions about the content. It assumes textual content that contains acronyms, an assumption which is known to hold for...

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