scholarly journals Mass Movements Susceptibility analysis and Assessment of Associeted Risks along the Southern Escarpment of the Bamileke Plateaus (West-Cameroon Highlands)

2021 ◽  
Author(s):  
Raoul Merlin NDONBOU ◽  
David Guimolaire Nkouathio ◽  
Ghislain ZANGMO TEFOGOUM ◽  
Christian Suh GUEDJEO ◽  
Sylvie Noelle DJUKEM FENGUIA ◽  
...  
Keyword(s):  
High Probability ◽  
Mass Movement ◽  
Bare Soil ◽  
Anthropogenic Factors ◽  
Susceptibility Map ◽  
Mass Movements ◽  
Anthropogenic Action ◽  
Low Probability ◽  
Geological Formations ◽  
Slope Direction

Abstract The Southern Escarpment of the Bamileke Plateaux (SEBP) is an area frequently affected by mass movements. An analysis of the susceptibility of these hazards is important in order to better understand these mountain processes. Field campaigns as well as the exploitation of satellite images in the laboratory have made it possible to inventory all sites subject to mass movements in the region. The region is affected by landslides, block falls and subsidence. Landslides are the most frequent hazard in the region. These hazards are regulated by about 10 natural and anthropogenic factors which include lithology, geomorphology, anthropogenic action, soil, proximity to roads, proximity to watercourses, density of watercourses, slope, direction of slopes, and curvature of slopes. The steepest slopes are between 27 and 90°, the most important slopes are oriented Nord-West. The curvature of the slopes shows zero, convex and concave slopes. The soils in the area are ferralitic, humus-bearing and hydromorphic. The land use shows bare soil and cultivated soil. The geomorphology shows altitudes ˃ 1319m, the highest stream densities range from 183-293m and constitute the significant proximities causing instabilities. In relation to the different classes of river proximity, the highest river proximities are ˃120m. The highest road proximities are ˃ 50m relative to the other road proximity classes. The geological formations that dominate the area are basalts, mylonites, granites gneisses and charnokites. These factors were mapped and the different maps were overlaid to obtain a mass movement susceptibility map of the study area. This map shows that 16.95% represent low probability areas, 43.39% represent moderate probability areas, 29.77% represent high probability areas and 9.89% represent very high probability areas. The majority of mass movements, especially landslides, are located in the high probability areas.

The effect of forest fire on mass movement in Lebanese mountainous areas

2014 ◽  
Vol 23 (6) ◽  
pp. 845
Author(s):  
Rouba Ziadé ◽  
Chadi Abdallah ◽  
Nicolas Baghdadi
Keyword(s):  
Forest Fire ◽  
Satellite Images ◽  
Mass Movement ◽  
Potential Effect ◽  
Burn Severity ◽  
Susceptibility Map ◽  
Mass Movements ◽  
Mountainous Areas ◽  
Effect Factors ◽  
Landsat Images

Mass movements are major hazards that threaten natural and human environments. In Lebanon, the occurrence of mass movements increased by almost 60% between 1956 and 2008. Forest fire has emerged as an additional hazard: it destroyed over 25% of Lebanon’s forests in a period less than 40 years. This paper investigates the potential effect of forest fire on the occurrence of mass movements in the Damour and Nahr Ibrahim watersheds of Lebanon. Mass movement and forest fire inventory maps were produced through remote sensing using aerial and satellite images. Forest fire was included as an additional factor in mass movement induction, and its effect was quantified from Landsat images through the normalised burn ratio (NBR) index. A field study was conducted to substantiate the mass movement inventory and NBR maps. Following the standardisation of the effect factors into layers using geographic information systems, the weight factor of each layer for inducing mass movements was evaluated using the modified InfoVal method, and a mass movement susceptibility map was generated. Exceeded only by changes in land cover, the NBR produced the highest weights, making forest fire burn severity the second highest factor influencing mass movement occurrence in the study areas.

scholarly journals Distribution of landslides reconstructed from inventory data and estimation of landslide susceptibility in Hungary

2019 ◽  
pp. 255-267
Author(s):  
Edina Józsa ◽  
Dénes Lóczy ◽  
Mauro Soldati ◽  
Lucian Daniel Drăguţ ◽  
József Szabó
Keyword(s):  
Landslide Susceptibility ◽  
Background Information ◽  
Landslide Susceptibility Mapping ◽  
Anthropogenic Factors ◽  
Susceptibility Map ◽  
Mass Movements ◽  
Mountainous Regions ◽  
Elevation Model ◽  
The Individual ◽  
Surface Geology

The complexity of landslides makes it difficult to predict the spatial distribution of landslide susceptibility and hazard. Although in most European countries the basic preconditions for the occurrence of mass movements (rocks and topography) have been mapped in detail, the triggering factors (e.g. precipitation or earthquakes) are much less predictable. A detailed nation-wide inventory for Hungary provides a unique base for landslide susceptibility mapping. As the methodology for the assessment the technique applied in the ELSUS 1000 project was selected. The micro-regions of Hungary were identified where mass movements contribute to land degradation. The paper provides a statistical evaluation of the distribution of landslides, depicts landslide susceptibility on maps and reveals the role of anthropogenic factors in the generation of mass movements. The mid-resolution elevation model (SRTM1), land cover data (CLC50) and surface geology database (Mining and Geological Survey of Hungary) allowed for the derivation of a landslide susceptibility map more detailed than before. Along with its background information the map reflects and explains the differences in landslide susceptibility among the individual hilly and mountainous regions.

scholarly journals GEOSPATIAL MODEL FOR LARGE SCALE SEA CLIFF ROCKFALL SUSCEPTIBILITY MAPPING

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 341-347
Author(s):  
P. Redweik ◽  
R. Matildes ◽  
F. Marques
Keyword(s):  
Laser Scanning ◽  
Large Scale ◽  
Mass Movement ◽  
Susceptibility Map ◽  
Mass Movements ◽  
Aerial Photogrammetry ◽  
The Status ◽  
Logistic Regression Method ◽  
Definition Of ◽  
Gis Software

<p><strong>Abstract.</strong> Due to their relevance to the environment and economy, coastal areas are considered national strategic segments that should be preserved. Since erosion phenomena occur intensively in those areas, it is capital to monitor them in order to identify risk zones. In addition to national and regional studies, it is also necessary to conduct local monitoring of erosion prone areas, especially those which are often frequented by people, such as beaches limited by high cliffs. Large scale vertical mapping is necessary to model their susceptibility to mass movements, in order to provide adequate prevention, protection and assistance.</p> <p>Recent techniques like laser scanning or aerial photogrammetry using UAVs allow the definition of the status quo of a cliff wall and its situation a few years back. But to assess the susceptibility to rock mass movements in such cliff segments, inventories of past events are of primordial importance. These inventories allow applying several statistic models to better understand susceptibility together with a set of variables of internal and external nature regarding the cliff site.</p> <p>We present a case study focused on the beach of Ribeira d’Ilhas (Mafra, Portugal), where a workflow of terrestrial photogrammetry for present day situation and recovery of old analogue stereoscopic pairs (1999, 2000, 2003) was implemented. A mass movement inventory (1999-2014) was compiled by multitemporal comparison followed by a detailed characterization of the cliff using a GIS software. Finally, the application of the logistic regression method allowed the definition of a susceptibility map of the cliff wall towards the occurrence of mass movements.</p>

Spatial suppression due to statistical regularities is driven by distractor suppression not by target activation

2018 ◽  
Author(s):  
Michel Failing ◽  
Benchi Wang ◽  
Jan Theeuwes
Keyword(s):  
High Probability ◽  
Target Location ◽  
Target Selection ◽  
Visual Space ◽  
Alternative Interpretation ◽  
Distractor Location ◽  
Target Presentation ◽  
Statistical Regularities ◽  
Low Probability ◽  
Presentation Experiment

Where and what we attend to is not only determined by what we are currently looking for but also by what we have encountered in the past. Recent studies suggest that biasing the probability by which distractors appear at locations in visual space may lead to attentional suppression of high probability distractor locations which effectively reduces capture by a distractor but also impairs target selection at this location. However, in many of these studies introducing a high probability distractor location was tantamount to increasing the probability of the target appearing in any of the other locations (i.e. the low probability distractor locations). Here, we investigate an alternative interpretation of previous findings according to which attentional selection at high probability distractor locations is not suppressed. Instead, selection at low probability distractor locations is facilitated. In two visual search tasks, we found no evidence for this hypothesis: neither when there was only a bias in target presentation but no bias in distractor presentation (Experiment 1), nor when there was only a bias in distractor presentation but no bias in target presentation (Experiment 2). We conclude that recurrent presentation of a distractor in a specific location leads to attentional suppression of that location through a mechanism that is unaffected by any regularities regarding the target location.

Validation of a machine learned model to predict the diagnosis of myocardial infarction

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
D Doudesis ◽  
J Yang ◽  
A Tsanas ◽  
C Stables ◽  
A Shah ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Coronary Syndrome ◽  
Predictive Value ◽  
High Probability ◽  
Cardiovascular Death ◽  
Gradient Boosting ◽  
Funding Source ◽  
Coronary Syndrome ◽  
Low Probability ◽  
One Year

Abstract Introduction The myocardial-ischemic-injury-index (MI3) is a promising machine learned algorithm that predicts the likelihood of myocardial infarction in patients with suspected acute coronary syndrome. Whether this algorithm performs well in unselected patients or predicts recurrent events is unknown. Methods In an observational analysis from a multi-centre randomised trial, we included all patients with suspected acute coronary syndrome and serial high-sensitivity cardiac troponin I measurements without ST-segment elevation myocardial infarction. Using gradient boosting, MI3 incorporates age, sex, and two troponin measurements to compute a value (0–100) reflecting an individual's likelihood of myocardial infarction, and estimates the negative predictive value (NPV) and positive predictive value (PPV). Model performance for an index diagnosis of myocardial infarction, and for subsequent myocardial infarction or cardiovascular death at one year was determined using previously defined low- and high-probability thresholds (1.6 and 49.7, respectively). Results In total 20,761 of 48,282 (43%) patients (64±16 years, 46% women) were eligible of whom 3,278 (15.8%) had myocardial infarction. MI3 was well discriminated with an area under the receiver-operating-characteristic curve of 0.949 (95% confidence interval 0.946–0.952) identifying 12,983 (62.5%) patients as low-probability (sensitivity 99.3% [99.0–99.6%], NPV 99.8% [99.8–99.9%]), and 2,961 (14.3%) as high-probability (specificity 95.0% [94.7–95.3%], PPV 70.4% [69–71.9%]). At one year, subsequent myocardial infarction or cardiovascular death occurred more often in high-probability compared to low-probability patients (17.6% [520/2,961] versus 1.5% [197/12,983], P&lt;0.001). Conclusions In unselected consecutive patients with suspected acute coronary syndrome, the MI3 algorithm accurately estimates the likelihood of myocardial infarction and predicts probability of subsequent adverse cardiovascular events. Performance of MI3 at example thresholds Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Medical Research Council

scholarly journals Prediction of Patients with Acute Cholecystitis Requiring Emergent Cholecystectomy: A Simple Score

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Wael N. Yacoub ◽  
Mikael Petrosyan ◽  
Indu Sehgal ◽  
Yanling Ma ◽  
Parakrama Chandrasoma ◽  
...  
Keyword(s):  
Heart Rate ◽  
Logistic Regression ◽  
Acute Cholecystitis ◽  
High Probability ◽  
Acute Inflammation ◽  
Gallbladder Wall ◽  
Cutoff Score ◽  
Gangrenous Cholecystitis ◽  
Pathological Review ◽  
Low Probability

The objective was to develop a score, to stratify patients with acute cholecystitis into high, intermediate, or low probability of gangrenous cholecystitis. The probability of gangrenous cholecystitis (score) was derived from a logistic regression of a clinical and pathological review of 245 patients undergoing urgent cholecystectomy. Sixty-eight patients had gangrenous inflammation, 132 acute, and 45 no inflammation. The score comprised of: age > 45 years (1 point), heart rate > 90 beats/min (1 point), male (2 points), Leucocytosis > 13,000/mm3(1.5 points), and ultrasound gallbladder wall thickness>4.5 mm (1 point). The prevalence of gangrenous cholecystitis was 13% in the low-probability (0–2 points), 33% in the intermediate-probability (2–4.5 points), and 87% in the high probability category (>4.5 points). A cutoff score of 2 identified 31 (69%) patients with no acute inflammation (PPV 90%). This scoring system can prioritize patients for emergent cholecystectomy based on their expected pathology.

Frequency of enforcement is more important than the severity of punishment in reducing violation behaviors

2021 ◽  
Vol 118 (42) ◽  
pp. e2108507118
Author(s):  
Kinneret Teodorescu ◽  
Ori Plonsky ◽  
Shahar Ayal ◽  
Rachel Barkan
Keyword(s):  
High Probability ◽  
Real Life ◽  
Expected Value ◽  
Relative Importance ◽  
Decisions From Experience ◽  
High Severity ◽  
Low Probability ◽  
Violation Rate ◽  
Severity Of Punishment ◽  
Enforcement Policies

External enforcement policies aimed to reduce violations differ on two key components: the probability of inspection and the severity of the punishment. Different lines of research offer different insights regarding the relative importance of each component. In four studies, students and Prolific crowdsourcing participants (Ntotal = 816) repeatedly faced temptations to commit violations under two enforcement policies. Controlling for expected value, we found that a policy combining a high probability of inspection with a low severity of fines (HILS) was more effective than an economically equivalent policy that combined a low probability of inspection with a high severity of fines (LIHS). The advantage of prioritizing inspection frequency over punishment severity (HILS over LIHS) was greater for participants who, in the absence of enforcement, started out with a higher violation rate. Consistent with studies of decisions from experience, frequent enforcement with small fines was more effective than rare severe fines even when we announced the severity of the fine in advance to boost deterrence. In addition, in line with the phenomenon of underweighting of rare events, the effect was stronger when the probability of inspection was rarer (as in most real-life inspection probabilities) and was eliminated under moderate inspection probabilities. We thus recommend that policymakers looking to effectively reduce recurring violations among noncriminal populations should consider increasing inspection rates rather than punishment severity.

Portable Ventilation/Perfusion Scanning is Useful for Evaluating Clinically Significant Pulmonary Embolism in the ICU Despite Abnormal Chest Radiography

2018 ◽  
Vol 35 (10) ◽  
pp. 1032-1038 ◽  
Author(s):  
Aaron S. Weinberg ◽  
William Chang ◽  
Grace Ih ◽  
Alan Waxman ◽  
Victor F. Tapson
Keyword(s):  
Pulmonary Embolism ◽  
Chest Radiograph ◽  
High Probability ◽  
Hemodynamic Instability ◽  
X Rays ◽  
X Ray ◽  
Abnormal Chest ◽  
Chest X Ray ◽  
Low Probability ◽  
Clinically Significant

Objective: Computed tomography angiography is limited in the intensive care unit (ICU) due to renal insufficiency, hemodynamic instability, and difficulty transporting unstable patients. A portable ventilation/perfusion (V/Q) scan can be used. However, it is commonly believed that an abnormal chest radiograph can result in a nondiagnostic scan. In this retrospective study, we demonstrate that portable V/Q scans can be helpful in ruling in or out clinically significant pulmonary embolism (PE) despite an abnormal chest x-ray in the ICU. Design: Two physicians conducted chart reviews and original V/Q reports. A staff radiologist, with 40 years of experience, rated chest x-ray abnormalities using predetermined criteria. Setting: The study was conducted in the ICU. Patients: The first 100 consecutive patients with suspected PE who underwent a portable V/Q scan. Interventions: Those with a portable V/Q scan. Results: A normal baseline chest radiograph was found in only 6% of patients. Fifty-three percent had moderate, 24% had severe, and 10% had very-severe radiographic abnormalities. Despite the abnormal x-rays, 88% of the V/Q scans were low probability for a PE despite an average abnormal radiograph rating of moderate. A high-probability V/Q for PE was diagnosed in 3% of the population despite chest x-ray ratings of moderate to severe. Six patients had their empiric anticoagulation discontinued after obtaining the results of the V/Q scan, and no anticoagulation was started for PE after a low-probability V/Q scan. Conclusion: Despite the large percentage of moderate-to-severe x-ray abnormalities, PE can still be diagnosed (high-probability scan) in the ICU with a portable V/Q scan. Although low-probability scans do not rule out acute PE, it appeared less likely that any patient with a low-probability V/Q scan had severe hypoxemia or hemodynamic instability due to a significant PE, which was useful to clinicians and allowed them to either stop or not start anticoagulation.

scholarly journals Identificação de Cicatrizes de Movimentos de Massa na Borda Oriental da Bacia do Paraná com base em Imagens Landsat 5-TM (Identification of Landslides Scars in the Eastern Edge of the Paraná Basin)

2015 ◽  
Vol 8 (1) ◽  
pp. 056
Author(s):  
Mariana Madruga De Brito
Keyword(s):  
Image Processing ◽  
Mass Movement ◽  
Google Earth ◽  
Economic Losses ◽  
Mass Movements ◽  
Tm Image ◽  
Paraná Basin ◽  
Landsat 5 Tm ◽  
Parana Basin ◽  
Eastern Edge

Movimentos de massa são fenômenos naturais caracterizados pelo deslocamento de solo e rocha vertente abaixo. Quando esses processos ocorrem em áreas urbanizadas, podem causar perdas econômicas, impactos sociais e, em casos extremos, perda de vidas humanas. Na tentativa de mitigar tais desastres, torna-se necessário mapear os locais já afetados pelos mesmos, uma vez que escorregamentos recentes podem sugerir futuros padrões de instabilidade. Nesse sentido, este trabalho teve por objetivo mapear as cicatrizes de movimentos de massa em um segmento da Borda Oriental da Bacia do Paraná, por meio do processamento de uma imagem Landsat 5-TM, órbita/ponto 220/80, data de passagem 28/08/2009. Para facilitar a discriminação destas feições, elaboraram-se composições coloridas RGB e processamentos tais como Ampliação Linear de Contraste (ALC), razão entre bandas e Análise por Componentes Principais (PCA). A fim de validar o inventário elaborado, utilizaram-se imagens de alta resolução disponíveis no software Google Earth®. Ao total, foram identificadas 63 cicatrizes com a imagem Landsat 5-TM e 121 cicatrizes com as imagens do Google Earth®. Os principais tipos de movimentos de massa mapeados são escorregamentos translacionais rasos e corrida de detritos. A identificação das cicatrizes foi possível devido às diferenças de tonalidade, cor, matiz e textura nas imagens orbitais após a ocorrência desses processos. Os resultados obtidos representam um passo inicial para a análise da suscetibilidade da área.     A B S T R A C T Mass movements are natural phenomena characterized by the downslope movement of soil and rock. When these processes occur in urban areas they can cause economic losses, social impacts and, in extreme cases, loss of human lives. In an attempt to mitigate such disasters, it is necessary to map sites affected by them, since recent landslides may suggest future patterns of instability. In this sense, this study aimed to map the mass movement scars in a segment of the Eastern Edge of the Paraná Basin, through the processing of a Landsat 5-TM image, 220/80 orbit-point and date of passage 08/28/2009. To facilitate the recognition of these features, RGB color compositions and image processing techniques such as contrast stretching, ratio between bands and Principal Component Analysis (PCA) were applied. In order to validate the inventory, high-resolution images available at Google Earth® software were used. Totally, 63 scars were identified with the Landsat 5-TM image and 121 with Google Earth® images. The main types of mass movements mapped are translational landslides and debris flows. The identification of the scars was possible due to differences in tone, color, hue and texture at the orbital images after the occurrence of such processes. Results obtained represent an initial step towards the susceptibility analysis of the area. Keywords: Landslide inventory; Digital image processing; Satellite images; Geoprocessing.  

scholarly journals Application of a mass movement susceptibility model in the heterogeneous Miocene clastic successions of the Slovenj Gradec Basin, northeast Slovenia

2020 ◽  
Vol 60 (1) ◽  
Author(s):  
Kristina Ivančič ◽  
Jernej Jež ◽  
Blaž Milanič ◽  
Špela Kumelj ◽  
Andrej Šmuc
Keyword(s):  
Land Use ◽  
Spatial Planning ◽  
Landscape Architecture ◽  
Mass Movement ◽  
Mass Movements ◽  
Structural Elements ◽  
Susceptibility Maps ◽  
Susceptibility Model ◽  
Lithological Composition ◽  
Geological Research

In Slovenia, mass movements are not only a threat to the population, but also a major environmental and social science challenge. Lithologically heterogeneous areas have been found to be problematic, and the Miocene Slovenj Gradec basin (in northeast Slovenia) is one such area. For this area, we developed landslide and rockfall susceptibility maps based on detailed geological research combined with statistical modeling schemes. Crucial factors include lithological composition, land use, geological structural elements, slope curvature, aspect and inclination, and bed dipping. The approach taken in the development of mass movement susceptibility maps presented here is transferable to other areas defined by heterogeneous lithology. Such maps could prove useful spatial planning, forestry, environmental protection, landscape architecture, and other fields.

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