scholarly journals Analysing riverbed morphology as a response to changes of geological and neotectonic conditions: A case study of the oľšava river

2019 ◽  
Vol 38 (3) ◽  
pp. 109-122
Author(s):  
Dušan Barabas ◽  
Matúš Tkáč
Keyword(s):  
Field Measurements ◽  
Water Area ◽  
Repeated Measurements ◽  
Longitudinal Profile ◽  
Width Ratio ◽  
Morphological Parameters ◽  
Morphological Examination ◽  
River Bed ◽  
The Difference ◽  
Width Measurements

Abstract The morphological examination of the Slovak Oľšava River channel and valley parameters is based on observation of changes in the troughs’ longitudinal profile. While the relationship between valley and channel parameters has previously been researched, establishment of the diverse conditions in trough formation enables better understanding of the basin/riverbed relationship. Our research is based on field measurements of representative sections of nine segments defined by changes in the longitudinal profile. The field measurements were performed in autumn months during a low water period to ensure the best conditions for repeated measurements. Significantly, as much as 75% asymmetry of the measured flow encourages the assumption of strong tectonic influence on the riverbed formation. While the difference between the assumed continuous changes of measured parameters and the actual measured or evaluated parameters remains a matter of interpretation, the detected anomalies enable interpretation of the parameters’ relationships. The river bed and the valley morphological parameters were evaluated on the model of The Olšava River basin which drains the eastern part of the Košická kotlina Basin (the Toryská pahorkatina Upland). The location of the basin at the foot of the Slanské vrchy Mts. is an important factor in the formation of the river network asymmetries. Both the Neogene contact between the Slanské vrchy Hills neo-volcanites and the Toryská pahorkatina Upland and the neo-tectonics influenced the change in morphological parameters in the valley’s longitudinal and transverse profile and the Oľšava river bed. Our terrain works comprised length and width measurements of the bars, their positions in the river bed, the width and depth of the channel and the type of section riffle. Available maps enabled calculation of the following; ratio of valley height to width, average gradient of the section, stream gradient index, average channel segment slope, the degree of sinuosity and the highest observed correlation between slope, river segment type (0.9576) and the width and type river reach (−0.9089). High correlation coefficient values were recorded for the valley height and width ratio, the type of river section, the water area and the total river bed width and area.

Use of a Lyophilized Reference Plasma to Compare Coagulation Test Procedures

1975 ◽  
Vol 34 (02) ◽  
pp. 426-444 ◽  
Author(s):  
J Kahan ◽  
I Nohén
Keyword(s):  
Oral Anticoagulant Therapy ◽  
Repeated Measurements ◽  
Test Procedures ◽  
Coagulation Activity ◽  
Close Relationship ◽  
Measured Activity ◽  
Test Materials ◽  
The Difference ◽  
The Stability ◽  
The One

SummaryIn 4 collaborative trials, involving a varying number of hospital laboratories in the Stockholm area, the coagulation activity of different test materials was estimated with the one-stage prothrombin tests routinely used in the laboratories, viz. Normotest, Simplastin-A and Thrombotest. The test materials included different batches of a lyophilized reference plasma, deep-frozen specimens of diluted and undiluted normal plasmas, and fresh and deep-frozen specimens from patients on long-term oral anticoagulant therapy.Although a close relationship was found between different methods, Simplastin-A gave consistently lower values than Normotest, the difference being proportional to the estimated activity. The discrepancy was of about the same magnitude on all the test materials, and was probably due to a divergence between the manufacturers’ procedures used to set “normal percentage activity”, as well as to a varying ratio of measured activity to plasma concentration. The extent of discrepancy may vary with the batch-to-batch variation of thromboplastin reagents.The close agreement between results obtained on different test materials suggests that the investigated reference plasma could be used to calibrate the examined thromboplastin reagents, and to compare the degree of hypocoagulability estimated by the examined PIVKA-insensitive thromboplastin reagents.The assigned coagulation activity of different batches of the reference plasma agreed closely with experimentally obtained values. The stability of supplied batches was satisfactory as judged from the reproducibility of repeated measurements. The variability of test procedures was approximately the same on different test materials.

COMPARATIVE EVALUATION OF MULTIPARAMETRIC ENDORECTAL ULTRASOUND AND ENHANCED IMAGING COLONOSCOPY IN THE DIAGNOSIS OF EARLY COLORECTAL CANCER

2020 ◽  
Vol 19 (3) ◽  
pp. 49-64
Author(s):  
E. M. Bogdanova ◽  
Yu. L. Trubacheva ◽  
O. M. Yugai ◽  
S. V. Chernyshov ◽  
E. G. Rybakov ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Statistical Significance ◽  
Muscle Layer ◽  
Endorectal Ultrasound ◽  
Diagnostic Methods ◽  
Early Colorectal Cancer ◽  
Morphological Examination ◽  
Optical Magnification ◽  
The Difference ◽  
Enhanced Imaging

AIM: to compare multiparametric endorectal ultrasound (ERUS) and enhanced imaging colonoscopy in the diagnosis of early colorectal cancer.PATIENTS AND METHODS: the study included 78 patients with epithelial rectal tumor. All the patients underwent multiparametric ERUS and colonoscopy with examination by narrow beam imaging (NBI) at optical magnification. All the patients were operated.RESULTS: a morphological examination removed specimens revealed adenomas in 48 cases, in 19 specimens – adenocarcinomas in situ and T1, and in 11 specimens – adenocarcinomas with invasion of the muscle layer or deeper. When calculating the accuracy indicators of diagnostic methods for groups of patients with adenoma, Tis-T1 adenocarcinoma, and T2-T3 adenocarcinoma, the difference in the sensitivity and specificity of the methods in none of the presented groups did not reach the level of statistical significance (p>0.05).ROC analysis showed that ultrasound has a prognostic value comparable to colonoscopy. The area difference was 0.013 (p=0.85).CONCLUSION: endoscopy and ultrasound have similar value in the diagnosis of malignant transformation of rectal adenomas.

scholarly journals Tower Running—Participation, Performance Trends, and Sex Difference

2020 ◽  
Vol 17 (6) ◽  
pp. 1902 ◽  
Author(s):  
Daniel Stark ◽  
Stefania Di Gangi ◽  
Caio Victor Sousa ◽  
Pantelis Nikolaidis ◽  
Beat Knechtle
Keyword(s):  
Sex Differences ◽  
Statistical Model ◽  
Sex Difference ◽  
Random Effects ◽  
Age Groups ◽  
Repeated Measurements ◽  
Stair Climbing ◽  
Age Group ◽  
Performance Trends ◽  
The Difference

Though there are exhaustive data about participation, performance trends, and sex differences in performance in different running disciplines and races, no study has analyzed these trends in stair climbing and tower running. The aim of the present study was therefore to investigate these trends in tower running. The data, consisting of 28,203 observations from 24,007 climbers between 2014 and 2019, were analyzed. The effects of sex and age, together with the tower characteristics (i.e., stairs and floors), were examined through a multivariable statistical model with random effects on intercept, at climber’s level, accounting for repeated measurements. Men were faster than women in each age group (p < 0.001 for ages ≤69 years, p = 0.003 for ages > 69 years), and the difference in performance stayed around 0.20 km/h, with a minimum of 0.17 at the oldest age. However, women were able to outperform men in specific situations: (i) in smaller buildings (<600 stairs), for ages between 30 and 59 years and >69 years; (ii) in higher buildings (>2200 stairs), for age groups <20 years and 60–69 years; and (iii) in buildings with 1600–2200 stairs, for ages >69 years. In summary, men were faster than women in this specific running discipline; however, women were able to outperform men in very specific situations (i.e., specific age groups and specific numbers of stairs).

scholarly journals Morphological variables associated with ruptured basilar tip aneurysms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jian Zhang ◽  
Anil Can ◽  
Pui Man Rosalind Lai ◽  
Srinivasan Mukundan ◽  
Victor M. Castro ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Multivariable Analysis ◽  
Aneurysm Rupture ◽  
Size Ratio ◽  
Width Ratio ◽  
Maximum Height ◽  
Morphological Parameters ◽  
Flow Angle ◽  
Aneurysm Wall ◽  
Fisher Grade

AbstractMorphological factors of intracranial aneurysms and the surrounding vasculature could affect aneurysm rupture risk in a location specific manner. Our goal was to identify image-based morphological parameters that correlated with ruptured basilar tip aneurysms. Three-dimensional morphological parameters obtained from CT-angiography (CTA) or digital subtraction angiography (DSA) from 200 patients with basilar tip aneurysms diagnosed at the Brigham and Women’s Hospital and Massachusetts General Hospital between 1990 and 2016 were evaluated. We examined aneurysm wall irregularity, the presence of daughter domes, hypoplastic, aplastic or fetal PCoAs, vertebral dominance, maximum height, perpendicular height, width, neck diameter, aspect and size ratio, height/width ratio, and diameters and angles of surrounding parent and daughter vessels. Univariable and multivariable statistical analyses were performed to determine statistical significance. In multivariable analysis, presence of a daughter dome, aspect ratio, and larger flow angle were significantly associated with rupture status. We also introduced two new variables, diameter size ratio and parent-daughter angle ratio, which were both significantly inversely associated with ruptured basilar tip aneurysms. Notably, multivariable analyses also showed that larger diameter size ratio was associated with higher Hunt-Hess score while smaller flow angle was associated with higher Fisher grade. These easily measurable parameters, including a new parameter that is unlikely to be affected by the formation of the aneurysm, could aid in screening strategies in high-risk patients with basilar tip aneurysms. One should note, however, that the changes in parameters related to aneurysm morphology may be secondary to aneurysm rupture rather than causal.

Electrical Discharge Grinding (EDG) of Polycrystalline Diamond - Effect of Machining Polarity

2014 ◽  
Vol 1025-1026 ◽  
pp. 628-632 ◽  
Author(s):  
Mohammad Zulafif Rahim ◽  
Song Lin Ding ◽  
John Mo
Keyword(s):  
Electrical Discharge ◽  
Complex Geometry ◽  
Polycrystalline Diamond ◽  
Machining Process ◽  
Morphological Examination ◽  
Carbon Structure ◽  
Finishing Process ◽  
Advanced Machining ◽  
The Difference ◽  
Pcd Tools

Electrical discharge grinding (EDG) is an advanced machining process and can be utilised to fabricate complex geometry of PCD tools. However, the PCD removal mechanism in this process is complicated. This study was carried out to understand the difference in PCD surface structure with difference EDG polarities. The study revealed that the finishing process with negative polarity is the reason for the porous structure on the surface. Further analysis on the chemical element and carbon structure were implemented as the morphological examination of the surface.

Reply to comments of D. H. Zeuch

1992 ◽  
Vol 7 (7) ◽  
pp. 1959-1960
Author(s):  
Hu Gengxiang ◽  
Chen Shipu ◽  
Wu Xiaohua ◽  
Chen Xiaofu
Keyword(s):  
Compression Test ◽  
Compression Testing ◽  
Width Ratio ◽  
Test Results ◽  
Specimen Length ◽  
The Difference

Compression test results of our research on Al3Ti-base alloys are reported. It is evident that the specimen length-to-width ratio we used for compression testing can significantly reflect the difference in ductility of different alloys. Thus the tests fulfilled the aim of our present research.

Radial diffusion coefficients database in the frame of SafeSpace project

2021 ◽  
Author(s):  
Christos Katsavrias ◽  
Ioannis A. Daglis ◽  
Afroditi Nasi ◽  
Constantinos Papadimitriou ◽  
Marina Georgiou
Keyword(s):  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Field Measurements ◽  
Radial Diffusion ◽  
Relativistic Electrons ◽  
Outer Radiation Belt ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
The Difference ◽  
Cycle 24

&lt;p&gt;Radial diffusion has been established as one of the most important mechanisms contributing the acceleration and loss of relativistic electrons in the outer radiation belt. Over the past few years efforts have been devoted to provide empirical relationships of radial diffusion coefficients (D&lt;sub&gt;LL&lt;/sub&gt;) for radiation belt simulations yet several studies have suggested that the difference between the various models can be orders of magnitude different at high levels of geomagnetic activity as the observed D&lt;sub&gt;LL&lt;/sub&gt; have been shown to be highly event-specific. In the frame of SafeSpace project we have used 12 years (2009 &amp;#8211; 2020) of multi-point magnetic and electric field measurements from THEMIS A, D and E satellites to create a database of calculated D&lt;sub&gt;LL&lt;/sub&gt;. In this work we present the first statistics on the evolution of D&lt;sub&gt;LL &lt;/sub&gt;during the various phases of Solar cycle 24 with respect to the various solar wind parameters and geomagnetic indices.&lt;/p&gt;&lt;p&gt;This work has received funding from the European Union's Horizon 2020 research and innovation programme &amp;#8220;SafeSpace&amp;#8221; under grant agreement No 870437.&lt;/p&gt;

scholarly journals 3D Numerical Study of the Flow Properties in a Double-Spur Dikes Field during a Flood Process

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1574 ◽  
Author(s):  
Xun Han ◽  
Pengzhi Lin
Keyword(s):  
Water Surface ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Field Measurements ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
River Bed ◽  
Hydrodynamic Evolution ◽  
Spur Dikes ◽  
Potential Damage

A 3D numerical model is developed to study the flow characteristics of a double-spur dikes field on Yangtze River during a flood process, which was presented by the variation of the flow condition. The model is based on Navier–Stokes (NS) equations, the porous medium method (PMM) is employed to treat the solid structures including the river bed surface, the volume of fluid (VOF) method is applied to track the motion of the water surface during the flood process, and large eddy simulation (LES) is adopted to capture the turbulence transport and dissipation. Using this model, the target reach’s flow field before the construction of double-spur dikes is simulated first, while the numerical results are compared to the field measurements on flow velocity and water surface level, and fairly good agreements are shown. Then, the model is applied to reproduce the hydrodynamic evolution during a flood process after double-spur dikes’ constructions, while the detailed 3D flow fields are obtained under some certain states with different submergence rates of the spur dikes; finally, the potential damage positions around these spur dikes are analyzed accordingly.

scholarly journals Field Study of Morphological Parameters in Step-Pool Streams

2018 ◽  
Vol 4 (8) ◽  
pp. 1930 ◽  
Author(s):  
Abbas Torbizadeh ◽  
Ahmad Tahershamsi ◽  
Mohammad Reza Majdzadeh Tabatabai
Keyword(s):  
Field Study ◽  
Cross Sections ◽  
Wave Length ◽  
Step Length ◽  
Morphological Parameters ◽  
Energy Field ◽  
Intermediate Morphology ◽  
Length Step ◽  
Successive Step ◽  
The Difference

Nowadays, step-pool formations have attracted a lot of attention, which are distinguished by the successive arrangements of the bed, suitable geometry, and the tumbling flow pattern, which can highly disperse water energy. Field study of a step–pool channel, along with one of the upper reaches of Kamandan River indicated a strong correlation between several morphological parameters of the river such as reach slope, step length, step height, pool depth, local slope, and the like. The length of the reach under the study is 145 meters and has an intermediate morphology based on Montgomery and Buffington’s classification. Therefore, twelve distinct step units were identified for 145 meters upstream while the rest was formed by steep morphology. In the present study, different definitions of wave length were applied to establish the relationships among the above parameters. For instance, the difference between apexes of every two successive step elevation was found to have a considerable relationship with the wavelength with a determination coefficient of 0.9. In addition, bankfull width and depth, along the profile for different cross-sections, were determined to establish a relationship between these parameters and pool spacing. Further, the parameters were applied to create a relationship with step heights.

scholarly journals River flow and sediment transport simulation based on a curvilinear and rectilinear grid modelling approach – a comparison study

2017 ◽  
Vol 17 (5) ◽  
pp. 1325-1334 ◽  
Author(s):  
G. G. Morianou ◽  
N. N. Kourgialas ◽  
G. P. Karatzas ◽  
N. P. Nikolaidis
Keyword(s):  
Sediment Transport ◽  
River Flow ◽  
Morphological Changes ◽  
Field Measurements ◽  
Grid Model ◽  
Curvilinear Grid ◽  
Saint Venant Equations ◽  
Flow And Sediment Transport ◽  
Downstream Section ◽  
The Difference

In the present work, a two-dimensional (2D) hydraulic model was used for the simulation of river flow and sediment transport in the downstream section of the Koiliaris River Basin in Crete, Greece, based on two different structured grids. Specifically, an important goal of the present study was the comparison of a curvilinear grid model with a rectilinear grid model. The MIKE 21C model has been developed to simulate 2D flows and morphological changes in rivers by using either an orthogonal curvilinear grid or a rectilinear grid. The MIKE 21C model comprises two parts: (a) the hydrodynamic part that is based on the Saint-Venant equations and (b) the morphological change part for the simulation of bank erosion and sediment transport. The difference between the curvilinear and the rectilinear grid is that the curvilinear grid lines follow the bank lines of the river, providing a better resolution of the flow near the boundaries. The water depth and sediment results obtained from the simulations for the two different grids were compared with field observations and a series of statistical indicators. It was concluded that the curvilinear grid model results were in better agreement with the field measurements.

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