scholarly journals Biotic responses to multiple aquatic and terrestrial gradients in shallow subarctic lakes (Old Crow Flats, Yukon, Canada)

2017 ◽  
Vol 3 (2) ◽  
pp. 277-300 ◽  
Author(s):  
A.M. Balasubramaniam ◽  
A.S. Medeiros ◽  
K.W. Turner ◽  
R.I. Hall ◽  
B.B. Wolfe
Keyword(s):  
Environmental Change ◽  
Variation Partitioning ◽  
Subarctic Lakes ◽  
Data Set ◽  
Sediment Properties ◽  
One Dimensional ◽  
Catchment Characteristics ◽  
Complex Interactions ◽  
Chironomid Assemblages ◽  
Old Crow Flats

Biotic communities in shallow northern lakes are frequently used to assess environmental change; however, complex interactions among multiple factors remain understudied. Here, we present analyses of a comprehensive data set that evaluates the influence input waters, catchment characteristics, limnology, and sediment properties on diatom and chironomid assemblages in surface sediments of ~49 shallow mainly thermokarst lakes in Old Crow Flats, Yukon. Multivariate analyses and ANOSIM tests identified that composition of diatom (119 taxa) and chironomid (68 taxa) assemblages differs significantly (p < 0.05) between lakes with snowmelt- versus rainfall-dominated input water. Redundancy analyses revealed strong correlation of limnological, sediment, and catchment variables with input waters. Variation partitioning analyses showed that unique effects of limnological variables account for the largest proportion of variation in diatom and chironomid assemblages (17.2% and 12.6%, respectively). Important independent roles of sediment properties (8.5% and 9.5%) and catchment characteristics (4.9% and 5.1%) were also identified. We suggest that the substantial variation shared among these classes (6.1% and 7.9%) is largely attributable to hydrological processes. Our study demonstrates the utility of multi-factor analysis in northern aquatic research and draws attention to the limitations of one-dimensional comparisons and their interpretations when modelling biotic responses to environmental change.

scholarly journals Simulation of the specific surface area of snow using a one-dimensional physical snowpack model: implementation and evaluation for subarctic snow in Alaska

2010 ◽  
Vol 4 (1) ◽  
pp. 35-51 ◽  
Author(s):  
H.-W. Jacobi ◽  
F. Domine ◽  
W. R. Simpson ◽  
T. A. Douglas ◽  
M. Sturm
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Winter Season ◽  
Data Set ◽  
Thermal Budget ◽  
One Dimensional ◽  
Snow Model ◽  
Physics Model ◽  
Snow Physics

Abstract. The specific surface area (SSA) of the snow constitutes a powerful parameter to quantify the exchange of matter and energy between the snow and the atmosphere. However, currently no snow physics model can simulate the SSA. Therefore, two different types of empirical parameterizations of the specific surface area (SSA) of snow are implemented into the existing one-dimensional snow physics model CROCUS. The parameterizations are either based on diagnostic equations relating the SSA to parameters like snow type and density or on prognostic equations that describe the change of SSA depending on snow age, snowpack temperature, and the temperature gradient within the snowpack. Simulations with the upgraded CROCUS model were performed for a subarctic snowpack, for which an extensive data set including SSA measurements is available at Fairbanks, Alaska for the winter season 2003/2004. While a reasonable agreement between simulated and observed SSA values is obtained using both parameterizations, the model tends to overestimate the SSA. This overestimation is more pronounced using the diagnostic equations compared to the results of the prognostic equations. Parts of the SSA deviations using both parameterizations can be attributed to differences between simulated and observed snow heights, densities, and temperatures. Therefore, further sensitivity studies regarding the thermal budget of the snowpack were performed. They revealed that reducing the thermal conductivity of the snow or increasing the turbulent fluxes at the snow surfaces leads to a slight improvement of the simulated thermal budget of the snowpack compared to the observations. However, their impact on further simulated parameters like snow height and SSA remains small. Including additional physical processes in the snow model may have the potential to advance the simulations of the thermal budget of the snowpack and, thus, the SSA simulations.

scholarly journals The environmental and evolutionary history of Lake Ohrid (FYROM/Albania): interim results from the SCOPSCO deep drilling project

2017 ◽  
Vol 14 (8) ◽  
pp. 2033-2054 ◽  
Author(s):  
Bernd Wagner ◽  
Thomas Wilke ◽  
Alexander Francke ◽  
Christian Albrecht ◽  
Henrike Baumgarten ◽  
...  
Keyword(s):  
Environmental Change ◽  
De Novo ◽  
Set Covering ◽  
Lake Ohrid ◽  
Climatic Impact ◽  
Deep Drilling ◽  
Proxy Data ◽  
Data Set ◽  
Drilling Project

Abstract. This study reviews and synthesises existing information generated within the SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) deep drilling project. The four main aims of the project are to infer (i) the age and origin of Lake Ohrid (Former Yugoslav Republic of Macedonia/Republic of Albania), (ii) its regional seismotectonic history, (iii) volcanic activity and climate change in the central northern Mediterranean region, and (iv) the influence of major geological events on the evolution of its endemic species. The Ohrid basin formed by transtension during the Miocene, opened during the Pliocene and Pleistocene, and the lake established de novo in the still relatively narrow valley between 1.9 and 1.3 Ma. The lake history is recorded in a 584 m long sediment sequence, which was recovered within the framework of the International Continental Scientific Drilling Program (ICDP) from the central part (DEEP site) of the lake in spring 2013. To date, 54 tephra and cryptotephra horizons have been found in the upper 460 m of this sequence. Tephrochronology and tuning biogeochemical proxy data to orbital parameters revealed that the upper 247.8 m represent the last 637 kyr. The multi-proxy data set covering these 637 kyr indicates long-term variability. Some proxies show a change from generally cooler and wetter to drier and warmer glacial and interglacial periods around 300 ka. Short-term environmental change caused, for example, by tephra deposition or the climatic impact of millennial-scale Dansgaard–Oeschger and Heinrich events are superimposed on the long-term trends. Evolutionary studies on the extant fauna indicate that Lake Ohrid was not a refugial area for regional freshwater animals. This differs from the surrounding catchment, where the mountainous setting with relatively high water availability provided a refuge for temperate and montane trees during the relatively cold and dry glacial periods. Although Lake Ohrid experienced significant environmental change over the last 637 kyr, preliminary molecular data from extant microgastropod species do not indicate significant changes in diversification rate during this period. The reasons for this constant rate remain largely unknown, but a possible lack of environmentally induced extinction events in Lake Ohrid and/or the high resilience of the ecosystems may have played a role.

Coral reef development drives molluscan diversity increase at local and regional scales in the late Neogene and Quaternary of the southwestern Caribbean

Paleobiology ◽  
2007 ◽  
Vol 33 (1) ◽  
pp. 24-52 ◽  
Author(s):  
Kenneth G. Johnson ◽  
Jonathan A. Todd ◽  
Jeremy B. C. Jackson
Keyword(s):  
Environmental Change ◽  
Shallow Water ◽  
Large Scale ◽  
Environmental Changes ◽  
Marine Biota ◽  
Environmental Distribution ◽  
Data Set ◽  
Ecological Response ◽  
Local Diversity ◽  
Late Neogene

The late Neogene was a time of major environmental change in Tropical America. Global cooling and associated oceanographic reorganization and the onset and intensification of glaciation in the Northern Hemisphere during the past ten million years coincided with the uplift of the Central American isthmus and resulting changes in regional oceanographic conditions. Previous analyses of patterns of taxonomic turnover and the shifting abundances of major ecological guilds indicated that the regional shallow-water marine biota responded to these environmental changes through extinction and via a restructuring of local benthic food webs, but it is not clear whether this ecological response had an effect on the diversity of molluscan assemblages in the region. Changes in regional and local diversity are often used as proxies for similar ecological response to environmental change in large-scale paleontological studies, but a clear relationship between diversity and ecological function has rarely been demonstrated in marine systems dominated by mollusks. To explore this relationship, we have compiled a data set of the stratigraphic and environmental distribution of genera of mollusks in large new collections of fossil specimens from the late Neogene and Recent of the southwestern Caribbean. Analysis of a selection of ecological diversity measures indicates that within shelf depths, assemblages from deeper water (51–200 m) were more diverse than shallow-water (<50 m) assemblages in the Pliocene. Lower diversity for shallow-water assemblages is caused by increased dominance of a few superabundant taxa in each assemblage. This implies that studies of diversity of shelf benthos need to control for relatively fine scaled environmental conditions if they are to avoid interpreting artifacts of uneven sampling as true change of diversity. For shallow-water assemblages only, there was significant increase in local and regional diversity of bivalve assemblages after the late Pliocene. No parallel increase in gastropods could be detected, but this likely is because sample size was inadequate for documenting the diversity of gastropod assemblages following a steep post-Pliocene decline of average gastropod abundance. Both the increasing bivalve diversity and the decrease in average abundance of gastropod taxa correspond to an interval of increasing carbonate deposition and reef building in the region, and are likely a result of increased fine-scale habitat heterogeneity controlled by the local distribution of carbonate buildups. Each of these results demonstrates that documenting the ecological response of tropical marine ecosystems to regional environmental change requires a large volume of fine-scaled samples with detailed paleoenvironmental control. Such data sets are rarely available from the fossil record.

Source water inputs and catchment characteristics regulate limnological conditions of shallow subarctic lakes (Old Crow Flats, Yukon, Canada)

2015 ◽  
Vol 72 (7) ◽  
pp. 1058-1072 ◽  
Author(s):  
Ann M. Balasubramaniam ◽  
Roland I. Hall ◽  
Brent B. Wolfe ◽  
Jon N. Sweetman ◽  
Xiaowa Wang
Keyword(s):  
Major Ions ◽  
Nutrient Concentrations ◽  
Source Water ◽  
Subarctic Lakes ◽  
Sparse Vegetation ◽  
Evaporative Concentration ◽  
Tall Shrub ◽  
Strong Control ◽  
Old Crow Flats ◽  
Source Waters

Climate variations exert rapid and strong control on the hydrology of shallow lake-rich subarctic landscapes, but knowledge of the associated effects on limnological conditions remains limited. Based on analysis of water isotope compositions and water chemistry at 56 lakes across Old Crow Flats (Yukon), a large thermokarst landscape, we assess if differences in source water inputs (snowmelt versus rainfall) affect limnological conditions during the ice-free season of 2007 and explore influences of catchment features. Results demonstrate that lakes with snowmelt-dominated source waters, situated in catchments that support tall shrub and woodland vegetation, possess significantly higher (p < 0.05) nutrient (N, P, SiO2) and dissolved organic carbon concentrations than lakes with rainfall-dominated source waters. Conversely, rainfall-dominated lakes, located in catchments dominated by dwarf shrubs and sparse vegetation, have significantly higher concentrations of major ions (Mg2+, Na+, SO42−) and pH. These limnological differences persisted throughout the ice-free season. We suggest that interaction of snowmelt with organic-rich detritus raises nutrient concentrations in snowmelt-dominated lakes and that evaporative-concentration, shoreline erosion and possibly rainfall runoff are processes that raise the ionic content of lakes with rainfall-dominated source waters. Knowledge of these relations improves the ability to anticipate limnological responses to ongoing and future climate and hydrological change in Arctic and subarctic regions.

Evidence Theory of One-Dimensional Compression KNN Classification Method

2010 ◽  
Vol 143-144 ◽  
pp. 1337-1341
Author(s):  
Wei Feng Yan ◽  
Gen Xiu Wu ◽  
Can Ze Li ◽  
Li Zhou
Keyword(s):  
Euclidean Distance ◽  
Evidence Theory ◽  
Numerical Data ◽  
Calculation Methods ◽  
Data Set ◽  
One Dimensional ◽  
Actual Distance ◽  
Distance Calculation ◽  
New Methods ◽  
Knn Classification

As only using Euclidean distance KNN algorithm has its limits, many researchers use other distance calculation methods as the replacement it to improve the accuracy of Data Classification. While combining the DS evidence theory with a series of KNN algorithm which discussed in this paper, we found that every algorithm has their merits. All of them ignore the analysis of the data set, through deeply analysis we found that the actual distance is determined by the larger value when two attribute values are in great difference. Therefore, what we do next is to compress the large-dimensional numerical data values. By this way, the accuracy of KNN, VSMKNN, KERKNN algorithm are obviously improved after experiment and then these new methods are called CDSKNN, CDSVSMKNN, CDSKERKNN.

scholarly journals Auxiliary Diagnostic Method for Patellofemoral Pain Syndrome Based on One-Dimensional Convolutional Neural Network

2021 ◽  
Vol 9 ◽  
Author(s):  
Wuxiang Shi ◽  
Yurong Li ◽  
Dujian Xu ◽  
Chen Lin ◽  
Junlin Lan ◽  
...  
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Diagnostic Method ◽  
Pain Syndrome ◽  
Patellofemoral Pain Syndrome ◽  
Patellofemoral Pain ◽  
Flexion Angle ◽  
Data Set ◽  
One Dimensional ◽  
Semg Signals

Early accurate diagnosis of patellofemoral pain syndrome (PFPS) is important to prevent the further development of the disease. However, traditional diagnostic methods for PFPS mostly rely on the subjective experience of doctors and subjective feelings of the patient, which do not have an accurate-unified standard, and the clinical accuracy is not high. With the development of artificial intelligence technology, artificial neural networks are increasingly applied in medical treatment to assist doctors in diagnosis, but selecting a suitable neural network model must be considered. In this paper, an intelligent diagnostic method for PFPS was proposed on the basis of a one-dimensional convolutional neural network (1D CNN), which used surface electromyography (sEMG) signals and lower limb joint angles as inputs, and discussed the model from three aspects, namely, accuracy, interpretability, and practicability. This article utilized the running and walking data of 41 subjects at their selected speed, including 26 PFPS patients (16 females and 10 males) and 16 painless controls (8 females and 7 males). In the proposed method, the knee flexion angle, hip flexion angle, ankle dorsiflexion angle, and sEMG signals of the seven muscles around the knee of three different data sets (walking data set, running data set, and walking and running mixed data set) were used as input of the 1D CNN. Focal loss function was introduced to the network to solve the problem of imbalance between positive and negative samples in the data set and make the network focus on learning the difficult-to-predict samples. Meanwhile, the attention mechanism was added to the network to observe the dimension feature that the network pays more attention to, thereby increasing the interpretability of the model. Finally, the depth features extracted by 1D CNN were combined with the traditional gender features to improve the accuracy of the model. After verification, the 1D CNN had the best performance on the running data set (accuracy = 92.4%, sensitivity = 97%, specificity = 84%). Compared with other methods, this method could provide new ideas for the development of models that assisted doctors in diagnosing PFPS without using complex biomechanical modeling and with high objective accuracy.

Hindered and compression settling: parameter measurement and modelling

2007 ◽  
Vol 56 (12) ◽  
pp. 101-110 ◽  
Author(s):  
A.-E. Stricker ◽  
I. Takács ◽  
A. Marquot
Keyword(s):  
Dynamic Models ◽  
Settling Velocity ◽  
Data Set ◽  
One Dimensional ◽  
New Methods ◽  
Number Of Layers ◽  
Point Analysis ◽  
Empirical Function ◽  
Settling Performance ◽  
Capacity Rating

The Vesilind settling velocity function forms the basis of flux theory used both in state point analysis (for design and capacity rating) and one-dimensional dynamic models (for dynamic process modelling). This paper proposes new methods to address known shortcomings of these methods, based on an extensive set of batch settling tests conducted at different scales. The experimental method to determine the Vesilind parameters from a series of bench scale settling tests is reviewed. It is confirmed that settling cylinders must be slowly stirred in order to represent settling performance of full scale plants for the whole range of solids concentrations. Two new methods to extract the Vesilind parameters from settling test series are proposed and tested against the traditional manual method. Finally, the same data set is used to propose an extension to one-dimensional (1-D) dynamic settler models to account for compression settling. Using the modified empirical function, the model is able to describe the batch settling interface independently of the number of layers.

scholarly journals LAKE 2.0: a model for temperature, methane, carbon dioxide and oxygen dynamics in lakes

2016 ◽  
Vol 9 (5) ◽  
pp. 1977-2006 ◽  
Author(s):  
Victor Stepanenko ◽  
Ivan Mammarella ◽  
Anne Ojala ◽  
Heli Miettinen ◽  
Vasily Lykosov ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Dynamics ◽  
Gas Transfer ◽  
Property A ◽  
Prognostic Variables ◽  
Data Set ◽  
One Dimensional ◽  
D Model ◽  
Oxygen Dynamics ◽  
Ch4 Transport

Abstract. A one-dimensional (1-D) model for an enclosed basin (lake) is presented, which reproduces temperature, horizontal velocities, oxygen, carbon dioxide and methane in the basin. All prognostic variables are treated in a unified manner via a generic 1-D transport equation for horizontally averaged property. A water body interacts with underlying sediments. These sediments are represented by a set of vertical columns with heat, moisture and CH4 transport inside. The model is validated vs. a comprehensive observational data set gathered at Kuivajärvi Lake (southern Finland), demonstrating a fair agreement. The value of a key calibration constant, regulating the magnitude of methane production in sediments, corresponded well to that obtained from another two lakes. We demonstrated via surface seiche parameterization that the near-bottom turbulence induced by surface seiches is likely to significantly affect CH4 accumulation there. Furthermore, our results suggest that a gas transfer through thermocline under intense internal seiche motions is a bottleneck in quantifying greenhouse gas dynamics in dimictic lakes, which calls for further research.

An Analytical One-Dimensional Penetration Model

2008 ◽  
Author(s):  
Sarah Reichwein ◽  
Stanley E. Jones
Keyword(s):  
Penetration Depth ◽  
High Speed ◽  
Large Data ◽  
Parameter Analysis ◽  
Strength Parameters ◽  
Data Set ◽  
Penetration Process ◽  
Dramatic Effect ◽  
One Dimensional ◽  
Metal On Metal

In an earlier paper, the authors extended the small parameter analysis of the classic Tate Equations presented by Walters, et al and to the modified penetration equations introduced previously by Jones, et al. The purpose of this extension was to provide an explicit solution to a complex system of nonlinear penetration equations in which penetrator mushrooming was considered, as well as erosion. This has a dramatic effect on the prediction of penetration depth for reasonable values of the strength parameters in the problem. The results were very encouraging and led to our increased understanding of the penetration process. In this paper, we further modify the equations for penetration depth by replacing the fundamental kinematical length relation, considered earlier, by one which was introduced by Wilson, et al. This change does not complicate the system because the mushroom strain is constant, but it does produce some significant changes. In this paper, the results of Cinnamon, et al are used to estimate the mushroom strain. However, instead of applying this result directly, we employ an averaging process to accommodate deviations from cylindrical crater geometry. The changes result in improved penetration depth estimates in high speed metal on metal impacts. A large data set is analyzed using the new results. Application to heavy metal impacts against armor targets is considered as an example.

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