scholarly journals Stream Boundary Detection of a Hyper-Arid, Polar Region Using a U-Net Architecture: Taylor Valley, Antarctica

2022 ◽  
Vol 14 (1) ◽  
pp. 234
Author(s):  
Mary C. Barlow ◽  
Xinxiang Zhu ◽  
Craig L. Glennie
Keyword(s):  
Polar Region ◽  
Training Dataset ◽  
Polar Regions ◽  
Arid Environments ◽  
Dry Valleys ◽  
Test Set ◽  
Meandering Streams ◽  
Taylor Valley ◽  
Novel Approach ◽  
Inflection Points

Convolutional neural networks (CNNs) are becoming an increasingly popular approach for classification mapping of large complex regions where manual data collection is too time consuming. Stream boundaries in hyper-arid polar regions such as the McMurdo Dry Valleys (MDVs) in Antarctica are difficult to locate because they have little hydraulic flow throughout the short summer months. This paper utilizes a U-Net CNN to map stream boundaries from lidar derived rasters in Taylor Valley located within the MDVs, covering ∼770 km2. The training dataset consists of 217 (300 × 300 m2) well-distributed tiles of manually classified stream boundaries with diverse geometries (straight, sinuous, meandering, and braided) throughout the valley. The U-Net CNN is trained on elevation, slope, lidar intensity returns, and flow accumulation rasters. These features were used for detection of stream boundaries by providing potential topographic cues such as inflection points at stream boundaries and reflective properties of streams such as linear patterns of wetted soil, water, or ice. Various combinations of these features were analyzed based on performance. The test set performance revealed that elevation and slope had the highest performance of the feature combinations. The test set performance analysis revealed that the CNN model trained with elevation independently received a precision, recall, and F1 score of 0.94±0.05, 0.95±0.04, and 0.94±0.04 respectively, while slope received 0.96±0.03, 0.93±0.04, and 0.94±0.04, respectively. The performance of the test set revealed higher stream boundary prediction accuracies along the coast, while inland performance varied. Meandering streams had the highest stream boundary prediction performance on the test set compared to the other stream geometries tested here because meandering streams are further evolved and have more distinguishable breaks in slope, indicating stream boundaries. These methods provide a novel approach for mapping stream boundaries semi-automatically in complex regions such as hyper-arid environments over larger scales than is possible for current methods.

scholarly journals Discovery of Highly Polymorphic Organic Materials: A New Machine Learning Approach

2019 ◽  
Author(s):  
Zied Hosni ◽  
Annalisa Riccardi ◽  
Stephanie Yerdelen ◽  
Alan R. G. Martin ◽  
Deborah Bowering ◽  
...  
Keyword(s):  
Machine Learning ◽  
Structure Prediction ◽  
External Validation ◽  
New Drugs ◽  
Training Dataset ◽  
Validation Dataset ◽  
Machine Learning Classification ◽  
Novel Approach ◽  
Physical Form ◽  
Machine Learning Approach

<div><div><p>Polymorphism is the capacity of a molecule to adopt different conformations or molecular packing arrangements in the solid state. This is a key property to control during pharmaceutical manufacturing because it can impact a range of properties including stability and solubility. In this study, a novel approach based on machine learning classification methods is used to predict the likelihood for an organic compound to crystallise in multiple forms. A training dataset of drug-like molecules was curated from the Cambridge Structural Database (CSD) and filtered according to entries in the Drug Bank database. The number of separate forms in the CSD for each molecule was recorded. A metaclassifier was trained using this dataset to predict the expected number of crystalline forms from the compound descriptors. This approach was used to estimate the number of crystallographic forms for an external validation dataset. These results suggest this novel methodology can be used to predict the extent of polymorphism of new drugs or not-yet experimentally screened molecules. This promising method complements expensive ab initio methods for crystal structure prediction and as integral to experimental physical form screening, may identify systems that with unexplored potential.</p> </div> </div>

scholarly journals Glacier mass balances (1993–2001), Taylor Valley, McMurdo Dry Valleys, Antarctica

2006 ◽  
Vol 52 (178) ◽  
pp. 451-462 ◽  
Author(s):  
Andrew G. Fountain ◽  
Thomas H. Nylen ◽  
Karen L. MacClune ◽  
Gayle L. Dana
Keyword(s):  
Mass Balance ◽  
Piecewise Linear ◽  
Objective Assessment ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Mass Balances ◽  
Missing Measurements ◽  
Wind Speeds ◽  
Taylor Valley ◽  
Air Temperatures

AbstractMass balances were measured on four glaciers in Taylor Valley, Antarctica, from 1993 to 2001. We used a piecewise linear regression, which provided an objective assessment of error, to estimate the mass balance with elevation. Missing measurements were estimated from linear regressions between points and showed a significant improvement over other methods. Unlike temperate glaciers the accumulation zone of these polar glaciers accumulates mass in summer and winter and the ablation zone loses mass in both seasons. A strong spatial trend of smaller mass-balance values with distance inland (r2 = 0.80) reflects a climatic gradient to warmer air temperatures, faster wind speeds and less precipitation. Annual and seasonal mass-balance values range only several tens of millimeters in magnitude and no temporal trend is evident. The glaciers of Taylor Valley, and probably the entire McMurdo Dry Valleys, are in equilibrium with the current climate, and contrast with glacier trends elsewhere on the Antarctic Peninsula and in temperate latitudes.

Climate and Hydrologic Variations and Implications for Lake and Stream Ecological Response in the McMurdo Dry Valleys, Antarctica

2003 ◽  
Author(s):  
Kathleen A. Welch ◽  
W. Berry Lyons
Keyword(s):  
New Zealand ◽  
Climatic Change ◽  
High Latitude ◽  
Lake Level ◽  
Climate Changes ◽  
Global Climate ◽  
Mcmurdo Dry Valleys ◽  
Polar Regions ◽  
Dry Valleys ◽  
Long Term Ecological Research

Because polar regions may amplify what would be considered small to moderate climate changes at lower latitudes, Weller (1998) proposed that the monitoring of high latitude regions should yield early evidence of global climate change. In addition to the climate changes themselves, the connections between the polar regions and the lower latitudes have recently become of great interest to meteorologists and paleoclimatologists alike. In the southern polar regions, the direct monitoring of important climatic variables has taken place only for the last few decades, largely because of their remoteness. This of course limits the extent to which polar records can be related to low latitude records, even at multiyear to decadal timescales. Climatologists and ecologists are faced with the problem that, even though these high latitude regions may provide important clues to global climatic change, the lengths of available records are relatively short. The McMurdo Dry Valleys Long-Term Ecological Research (MCM LTER) program was established in 1993. This program built on the monitoring begun in the late 1960s by researchers from New Zealand, who collected records of climate, lake level, and stream discharge in the Wright Valley, Antarctica. Griffith Taylor’s field party obtained the first data related to lake level in 1903 as part of Scott’s Discovery expedition. Analysis of the more recent data from the New Zealand Antarctic and MCM LTER programs when compared to the 1903 datum indicates that the first half of the twentieth century was a period of steadily increasing streamflows, followed in the last half of the century by streamflows that have resulted in more slowly increasing or stable lake levels (Bomblies et al. 2001). Thus, meteorological and hydrological records generated by the MCM LTER research team, when coupled with past data and the ecological information currently being obtained, provide the first detailed attempt to understand the connection between ecosystem structure and function and climatic change in this region of Antarctica. In addition, the program helps to fill an important gap in the overall understanding of climatic variability in Antarctica.

scholarly journals Braille Recognition for Reducing Asymmetric Communication between the Blind and Non-Blind

Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1069
Author(s):  
Bi-Min Hsu
Keyword(s):  
Neural Network ◽  
User Interfaces ◽  
Prediction Accuracy ◽  
Visually Impaired ◽  
Recognition System ◽  
Character Segmentation ◽  
English Text ◽  
Test Set ◽  
Novel Approach ◽  
Blind Individuals

Assistive braille technology has existed for many years with the purpose of aiding the blind in performing common tasks such as reading, writing, and communicating with others. Such technologies are aimed towards helping those who are visually impaired to better adapt to the visual world. However, an obvious gap exists in current technology when it comes to symmetric two-way communication between the blind and non-blind, as little technology allows non-blind individuals to understand the braille system. This research presents a novel approach to convert images of braille into English text by employing a convolutional neural network (CNN) model and a ratio character segmentation algorithm (RCSA). Further, a new dataset was constructed, containing a total of 26,724 labeled braille images, which consists of 37 braille symbols that correspond to 71 different English characters, including the alphabet, punctuation, and numbers. The performance of the CNN model yielded a prediction accuracy of 98.73% on the test set. The functionality performance of this artificial intelligence (AI) based recognition system could be tested through accessible user interfaces in the future.

scholarly journals Water tracks intensify surface energy and mass exchange in the Antarctic McMurdo Dry Valleys

2019 ◽  
Vol 13 (8) ◽  
pp. 2203-2219 ◽  
Author(s):  
Tobias Linhardt ◽  
Joseph S. Levy ◽  
Christoph K. Thomas
Keyword(s):  
Climate Change ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Dry Valleys ◽  
Sensible Heat ◽  
Net Radiation ◽  
Taylor Valley ◽  
The Antarctic

Abstract. The hydrologic cycle in the Antarctic McMurdo Dry Valleys (MDV) is mainly controlled by surface energy balance. Water tracks are channel-shaped high-moisture zones in the active layer of permafrost soils and are important solute and water pathways in the MDV. We evaluated the hypothesis that water tracks alter the surface energy balance in this dry, cold, and ice-sheet-free environment during summer warming and may therefore be an increasingly important hydrologic feature in the MDV in the face of landscape response to climate change. The surface energy balance was measured for one water track and two off-track reference locations in Taylor Valley over 26 d of the Antarctic summer of 2012–2013. Turbulent atmospheric fluxes of sensible heat and evaporation were observed using the eddy-covariance method in combination with flux footprint modeling, which was the first application of this technique in the MDV. Soil heat fluxes were analyzed by measuring the heat storage change in the thawed layer and approximating soil heat flux at ice table depth by surface energy balance residuals. For both water track and reference locations over 50 % of net radiation was transferred to sensible heat exchange, about 30 % to melting of the seasonally thawed layer, and the remainder to evaporation. The net energy flux in the thawed layer was zero. For the water track location, evaporation was increased by a factor of 3.0 relative to the reference locations, ground heat fluxes by 1.4, and net radiation by 1.1, while sensible heat fluxes were reduced down to 0.7. Expecting a positive snow and ground ice melt response to climate change in the MDV, we entertained a realistic climate change response scenario in which a doubling of the land cover fraction of water tracks increases the evaporation from soil surfaces in lower Taylor Valley in summer by 6 % to 0.36 mm d−1. Possible climate change pathways leading to this change in landscape are discussed. Considering our results, an expansion of water track area would make new soil habitats accessible, alter soil habitat suitability, and possibly increase biological activity in the MDV. In summary, we show that the surface energy balance of water tracks distinctly differs from that of the dominant dry soils in polar deserts. With an expected increase in area covered by water tracks, our findings have implications for hydrology and soil ecosystems across terrestrial Antarctica.

Detection of Automobile Insurance Fraud Using Feature Selection and Data Mining Techniques

2018 ◽  
Vol 5 (3) ◽  
pp. 1-20 ◽  
Author(s):  
Sharmila Subudhi ◽  
Suvasini Panigrahi
Keyword(s):  
Data Mining ◽  
Feature Selection ◽  
Feature Selection Method ◽  
Automobile Insurance ◽  
Test Set ◽  
Data Mining Techniques ◽  
Weighted Extreme Learning Machine ◽  
Original Dataset ◽  
Novel Approach ◽  
Learning Machine

This article presents a novel approach for fraud detection in automobile insurance claims by applying various data mining techniques. Initially, the most relevant attributes are chosen from the original dataset by using an evolutionary algorithm based feature selection method. A test set is then extracted from the selected attribute set and the remaining dataset is subjected to the Possibilistic Fuzzy C-Means (PFCM) clustering technique for the undersampling approach. The 10-fold cross validation method is then used on the balanced dataset for training and validating a group of Weighted Extreme Learning Machine (WELM) classifiers generated from various combinations of WELM parameters. Finally, the test set is applied on the best performing model for classification purpose. The efficacy of the proposed system is illustrated by conducting several experiments on a real-world automobile insurance defraud dataset. Besides, a comparative analysis with another approach justifies the superiority of the proposed system.

scholarly journals Span Model for Open Information Extraction on Accurate Corpus

2020 ◽  
Vol 34 (05) ◽  
pp. 9523-9530
Author(s):  
Junlang Zhan ◽  
Hai Zhao
Keyword(s):  
Information Extraction ◽  
State Of The Art ◽  
Training Dataset ◽  
Model Design ◽  
Test Set ◽  
Benchmark Test ◽  
Open Information Extraction ◽  
Test Sets ◽  
Improved Model ◽  
Benchmark Evaluation

Open Information Extraction (Open IE) is a challenging task especially due to its brittle data basis. Most of Open IE systems have to be trained on automatically built corpus and evaluated on inaccurate test set. In this work, we first alleviate this difficulty from both sides of training and test sets. For the former, we propose an improved model design to more sufficiently exploit training dataset. For the latter, we present our accurately re-annotated benchmark test set (Re-OIE2016) according to a series of linguistic observation and analysis. Then, we introduce a span model instead of previous adopted sequence labeling formulization for n-ary Open IE. Our newly introduced model achieves new state-of-the-art performance on both benchmark evaluation datasets.

scholarly journals Biodiversity and Habitats of Polar Region Polyhydroxyalkanoic Acid-Producing Bacteria: Bioprospection by Popular Screening Methods

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 873
Author(s):  
Małgorzata Marta Rogala ◽  
Jan Gawor ◽  
Robert Gromadka ◽  
Magdalena Kowalczyk ◽  
Jakub Grzesiak
Keyword(s):  
Polar Region ◽  
Screening Method ◽  
Nile Red ◽  
Screening Methods ◽  
Polar Regions ◽  
Bacterial Strains ◽  
Polyhydroxyalkanoic Acid ◽  
Technological Potential ◽  
Typical Morphology ◽  
Acid Producing Bacteria

Polyhydroxyalkanoates (PHAs), the intracellular polymers produced by various microorganisms as carbon and energy storage, are of great technological potential as biodegradable versions of common plastics. PHA-producing microbes are therefore in great demand and a plethora of different environments, especially extreme habitats, have been probed for the presence of PHA-accumulators. However, the polar region has been neglected in this regard, probably due to the low accessibility of the sampling material and unusual cultivation regime. Here, we present the results of a screening procedure involving 200 bacterial strains isolated from 25 habitats of both polar regions. Agar-based tests, microscopy, and genetic methods were conducted to elucidate the biodiversity and potential of polar-region PHA-accumulators. Microscopic observation of Nile Red stained cells proved to be the most reliable screening method as it allowed to confirm the characteristic bright orange glow of the Nile Red–PHA complex as well as the typical morphology of the PHA inclusions. Psychrophilic PHA-producers belonged mostly to the Comamonadaceae family (Betaproteobacteria) although actinobacterial PHA synthesizers of the families, Microbacteriaceae and Micrococcaceae also featured prominently. Glacial and postglacial habitats as well as developed polar region soils, were evaluated as promising for PHA-producer bioprospection. This study highlights the importance of psychrophiles as biodiverse and potent polyhydroxyalkanoate sources for scientific and application-aimed research.

scholarly journals A temperature-index model of stream flow at below-freezing temperatures in Taylor Valley, Antarctica

2005 ◽  
Vol 40 ◽  
pp. 76-82 ◽  
Author(s):  
Amy F. Ebnet ◽  
Andrew G. Fountain ◽  
Thomas H. Nylen ◽  
Diane M. Mcknight ◽  
Christopher L. Jaros
Keyword(s):  
Melting Rate ◽  
Coefficient Of Determination ◽  
Dry Valleys ◽  
The South ◽  
Index Model ◽  
The North ◽  
Taylor Valley ◽  
Air Temperatures ◽  
Glacial Runoff ◽  
Summer Temperatures

AbstractWe model runoff from glaciers in the McMurdo Dry Valleys, Antarctica, with summer (December–January) average air temperatures from 1990 to 2002 for the purpose of estimating decades- to millennial-scale glacial runoff into Lakes Fryxell, Hoare and Bonney. The relationship between summer temperatures and melt is found to be exponential near the melting temperature. We propose a variety of simple models that are calibrated using measured discharge from a number of streams draining from ten glaciers in Taylor Valley. The surface melting rate is constrained by mass-balance measurements from four of the glaciers. A model based solely on temperature produced good results (coefficient of determination, r2 = 0.71) for the south-facing glaciers, but poor results for the north-facing glaciers (r2 < 0). The inclusion of a solar radiation index increased the modeled melt from the north-facing glaciers and thus improved the results (r2 = 0.73) for the north-facing glaciers, with little change from the south-facing glaciers. Including a wind index did not improve the correlation between modeled and measured runoff.

scholarly journals The Changing Energy Balance of the Polar Regions in a Warmer Climate

2013 ◽  
Vol 26 (10) ◽  
pp. 3112-3129 ◽  
Author(s):  
Lennart Bengtsson ◽  
Kevin I. Hodges ◽  
Symeon Koumoutsaris ◽  
Matthias Zahn ◽  
Paul Berrisford
Keyword(s):  
Polar Region ◽  
Energy Transport ◽  
Climate Model ◽  
Radiant Energy ◽  
Surface Radiation ◽  
The Arctic ◽  
Polar Regions ◽  
Energy Fluxes ◽  
Intergovernmental Panel ◽  
Static Energy

Abstract Energy fluxes for polar regions are examined for two 30-yr periods, representing the end of the twentieth and twenty-first centuries, using data from high-resolution simulations with the ECHAM5 climate model. The net radiation to space for the present climate agrees well with data from the Clouds and the Earth’s Radiant Energy System (CERES) over the northern polar region but shows an underestimation in planetary albedo for the southern polar region. This suggests there are systematic errors in the atmospheric circulation or in the net surface energy fluxes in the southern polar region. The simulation of the future climate is based on the Intergovernmental Panel on Climate Change (IPCC) A1B scenario. The total energy transport is broadly the same for the two 30-yr periods, but there is an increase in the moist energy transport on the order of 6 W m−2 and a corresponding reduction in the dry static energy. For the southern polar region the proportion of moist energy transport is larger and the dry static energy correspondingly smaller for both periods. The results suggest a possible mechanism for the warming of the Arctic that is discussed. Changes between the twentieth and twenty-first centuries in the northern polar region show the net ocean surface radiation flux in summer increases ~18 W m−2 (24%). For the southern polar region the response is different as there is a decrease in surface solar radiation. It is suggested that this is caused by changes in cloudiness associated with the poleward migration of the storm tracks.

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