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1
Imhoff, Kurt S., and Andrew C. Wilcox. "Coarse bedload routing and dispersion through tributary confluences." Earth Surface Dynamics 4, no. 3 (July 26, 2016): 591–605. http://dx.doi.org/10.5194/esurf-4-591-2016.
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Abstract. Sediment routing fundamentally influences channel morphology and the propagation of disturbances such as debris flows. The transport and storage of bedload particles across headwater channel confluences, which may be significant nodes of the channel network in terms of sediment routing, morphology, and habitat, are poorly understood, however. We investigated patterns and processes of sediment routing through headwater confluences by comparing them to published results from lower-gradient confluences and by comparing the dispersive behavior of coarse bedload particles between headwater confluence and non-confluence reaches. We addressed these questions with a field tracer experiment using passive-integrated transponder and radio-frequency identification technology in the East Fork Bitterroot River basin, Montana, USA. Within the confluence zone, tracers tended to be deposited towards scour-hole and channel margins, suggesting narrow, efficient transport corridors that mirror those observed in prior studies, many of which are from finer-grained systems. Coarse particles in some confluence reaches experienced reduced depositional probabilities within the confluence relative to upstream and downstream of the confluence. Analysis of particle transport data suggests that variation in the spatial distribution of coarse-sediment particles may be enhanced by passing through confluences, though further study is needed to evaluate confluence effects on dispersive regimes and sediment routing on broader spatial and temporal scales.
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Bilal, Ahmed, Qiancheng Xie, and Yanyan Zhai. "Flow, Sediment, and Morpho-Dynamics of River Confluence in Tidal and Non-Tidal Environments." Journal of Marine Science and Engineering 8, no. 8 (August 7, 2020): 591. http://dx.doi.org/10.3390/jmse8080591.
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River confluences are the key features of the drainage basins, as their hydrological, geomorphological, and ecological nature strongly influences the downstream river characteristics. The river reaches near the coastal zones, which also makes them under the influence of tidal currents in addition to their runoff. This causes a bi-directional flow and makes the study of confluences more interesting and complex in these areas. There is a reciprocal adjustment of flow, sediment, and morphology at a confluence, and its behaviors, differ greatly in tidal and non-tidal environments. Existing studies of the river junctions provide a good account of information about the hydrodynamics and bed morphology of the confluent areas, especially the unidirectional ones. The main factors which affect the flow field include the angle of confluence, flow-related ratios (velocity, discharge, and momentum) of the merging streams, and bed discordance. Hydraulically, six notable zones are identified for unidirectional confluences. However, for bi-directional (tidal) junctions, hydrodynamic zones always remain in transition but repeat in a cycle and make four different arrangements of flow features. This study discusses the hydrodynamics, sediment transport, morphological changes, and the factors affecting these processes and reviews the recent research about the confluences for these issues. All of these studies provide insights into the morpho-dynamics in tidal and non-tidal confluent areas.
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St. Pierre Ostrander, Théo, Thomé Kraus, Bruno Mazzorana, Johannes Holzner, Andrea Andreoli, Francesco Comiti, and Bernhard Gems. "Limited effect of the confluence angle and tributary gradient on Alpine confluence morphodynamics under intense sediment loads." Natural Hazards and Earth System Sciences 24, no. 5 (May 8, 2024): 1607–34. http://dx.doi.org/10.5194/nhess-24-1607-2024.
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Abstract. Confluences are dynamic morphological nodes that are found in all river networks. In mountain regions, they are influenced by hydraulic and sedimentary processes that occur in steep channels during extreme events in small watersheds. Sediment transport in the tributary channel and aggradation in the confluence can be massive, potentially causing overbank flooding and sedimentation into adjacent settlement areas. Previous works dealing with confluences have mainly focused on lowland regions, and those that have focused on mountain areas have used sediment concentrations and channel gradients that are largely under-representative of mountain river conditions. The presented work contributes to filling this research gap with 45 experiments that use a large-scale physical model. Geometric model parameters, the applied grain size distribution, and the considered discharges represent the conditions at 135 confluences in South Tyrol (Italy) and Tyrol (Austria). The experimental program allowed for a comprehensive analysis of the effects of (i) the confluence angle, (ii) the tributary gradient, (iii) the channel discharges, and (iv) the tributary sediment concentration. In contrast to most research dealing with confluences, results indicate that, in the presence of an intense tributary sediment supply and a small tributary-to-main-channel discharge ratio (0.1), the confluence angle does not have a decisive effect on confluence morphology. Adjustments to the tributary channel gradient yielded the same results. A reoccurring range of depositional geomorphic units was observed in which a deposition cone transitioned to a bank-attached bar. The confluence morphology and tributary channel gradient rapidly adjusted, tending towards an equilibrium state to accommodate both water discharges and the sediment load from the tributary. Statistical analyses demonstrated that the confluence morphology was controlled by the combined channel discharge and the depositional or erosional extent was controlled by the sediment concentration. Applying conclusions drawn from lowland confluence dynamics could misrepresent depositional and erosional patterns and the related flood hazard at mountain river confluences.
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Chen, Sihan, Yingjin Li, Zhong Tian, and Qiang Fan. "On Dam-Break Flow Routing in Confluent Channels." International Journal of Environmental Research and Public Health 16, no. 22 (November 9, 2019): 4384. http://dx.doi.org/10.3390/ijerph16224384.
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The flood propagation at a confluence of channels exhibits a unique routing pattern, while there are few studies on the routing of dam-break flow in confluent channels. In this study, we conducted physical experiments and a numerical simulation to investigate the influence of different confluence angles on the routing of a dam-break flood. Experiments were carried out in smooth, transparent, rectangular prismatic channels to study the dam-break flow under four different confluence angles. The flow velocity was measured using an image processing technique, and the surface flow field was effectively captured by synchronously recording the particle motion images. Based on the variation of the water level and flow discharge, as the confluence angle increased, the retardation and abatement effects on the flood increased. Specifically, the flood arrival time was delayed by approximately 0.91% to 21.18%, and the peak flood discharge was reduced by approximately 9.05% to 58.36%. Combined with the surface flow field at the confluence and in the downstream sections, as the confluence angle increased, the impact points at the confluence and in the downstream straight sections moved upward, and the impact range was reduced. Combined with the pressure variation pattern, the routing of dam-break flow in the confluent channels experienced a process of impact-reflection-return-attenuation.
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van Rooijen, Erik, Erik Mosselman, Kees Sloff, and Wim Uijttewaal. "The Effect of Small Density Differences at River Confluences." Water 12, no. 11 (November 3, 2020): 3084. http://dx.doi.org/10.3390/w12113084.
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Remarkable 3D flow structures occur at river confluences with small density differences due to differences in sediment concentration or temperature. We explain these by comparing numerical simulations for an idealized confluence with aerial photographs of several river confluences where color differences express the pattern of density differences at the surface. We analyzed numerical simulations of the Rio Negro–Solimões confluence near Manaus, Brazil, in more detail. The numerical model of the idealized confluence showed that the dense water flowed under the light water and the light water over the dense water in a spiraling motion, distorting the interface between the two waters. The horizontal part of this interface moves upwards in downstream direction. Constraining of the spiraling motion in a narrow river downstream of the confluence can cause local up- and downwelling near the banks. A mixing layer can develop when the flow velocities of the two tributaries differ, but strong spiraling motion due to the density differences can suppress this development. The aerial photographs and all numerical simulations showed similar density patterns at the water surface. Even small density differences can have a significant impact and hence need to be considered when analyzing and modeling 3D flow at confluences.
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Đorđević, Dejana. "Numerical study of 3D flow at right-angled confluences with and without upstream planform curvature." Journal of Hydroinformatics 15, no. 4 (November 8, 2012): 1073–88. http://dx.doi.org/10.2166/hydro.2012.150.
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The purpose of this paper is to study the individual and combined effect of upstream planform curvature and difference in bed elevations at the tributary entrance to the confluence on the flow in the confluence hydrodynamics zone. To do this, flow at right-angled confluences with three planforms and four values of bed elevation discordance ratio (ΔzT/hd) is simulated using a three-dimensional (3D) numerical model. Three confluence planforms include confluences with the (1) straight tributary canal (SC), (2) right bend (RB) and (3) left bend (LB) in the tributary. Four ΔzT/hd values in the range [0.0, 0.5] include both concordant and discordant beds' confluences. Overall, nine cases with the straight main canal are considered. Special attention is paid to the flow deflection and flow separation zones since the former affects transfer of momentum from the tributary to the main canal and the latter affects transport capacity of the post-confluence channel. Comparison of the results reveals that the influence of RB in the tributary is practically negligible in comparison to the straight canal case. With the increasing difference in bed elevations between the tributary and main canals (ΔzT), the presence of LB strengthens 3D flow and the structure of the recirculation zone is destroyed.
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Wu, Szu-Hsien, Yu-Ting Liao, Chi-Han Huang, Yi-Chou Chen, En-Rung Chiang, and Jung-Pan Wang. "Comparison of the Confluence-Initiated Neurogenic Differentiation Tendency of Adipose-Derived and Bone Marrow-Derived Mesenchymal Stem Cells." Biomedicines 9, no. 11 (October 20, 2021): 1503. http://dx.doi.org/10.3390/biomedicines9111503.
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Adipose-derived mesenchymal stem cells (ADSCs), which tended to neurogenically differentiate spontaneously after achieving high confluence, were observed. Human ADSCs reaching 80% confluence were cultured in DMEM without an inducing factor for 24 h and then maintained in DMEM plus 1% FBS medium for 7 days. The neurogenic, adipogenic, and osteogenic genes of the factor-induced and confluence-initiated differentiation of the ADSCs and bone marrow-derived mesenchymal stem cells (BMSCs) at passages 3 to 5 were determined and compared using RT-qPCR, and the neurogenic differentiation was confirmed using immunofluorescent staining. In vitro tests revealed that the RNA and protein expression of neuronal markers, including class III β-tubulin (TUBB3), microtubule-associated protein 2 (MAP2), neurofilament medium polypeptide (NEFM), neurofilament heavy polypeptide (NEFH), and neurofilament light polypeptide (NEFL), had been enhanced in the confluence-initiated differentiation of the ADSCs. In addition, the expressions of neurotrophins, such as the nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and glial cell-derived neurotrophic factor (GDNF), were also elevated in the confluence-initiated differentiation of the ADSCs. However, the confluent ADSCs did not show a tendency toward spontaneous adipogenic and osteogenic differentiation. Moreover, compared with the confluent ADSCs, the tendency of spontaneous neurogenic, adipogenic, and osteogenic differentiation of the confluent human bone marrow mesenchymal stem cells (BMSCs) was not observed. The results indicated that ADSCs had the potential to spontaneously differentiate into neuron-like cells during the confluent culture period; however, this tendency was not observed in BMSCs.
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Bergeron, Normand, and André G. Roy. "Les effets d’un embâcle sur la morphologie du lit d’une confluence de cours d’eau." Géographie physique et Quaternaire 42, no. 2 (December 18, 2007): 191–96. http://dx.doi.org/10.7202/032725ar.
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RÉSUMÉLa morphologie du lit aux confluences est particulièrement sensible aux changements dans le rapport des débits entre les tributaires. En milieu nordique, les embâcles de glace situés en amont des confluences peuvent modifier les débits des tributaires et ainsi affecter les conditions hydrauliques de la confluence. Au printemps 1986, nous avons observé les effets d'un embâcle sur la morphologie du lit d'une confluence située dans le bassin du ruisseau du Sud, en Estrie, au Québec (45°20'N, 7V20'W). La formation de l'embâcle et sa rupture ont entraîné l'accumulation d'un banc graveleux à l'entrée du tributaire majeur, le surcreusement du tributaire mineur et le déplacement de la zone d'affouillement. Depuis la débâcle, les conditions d'écoulement se sont stabilisées et les sédiments sont graduellement redistribués sur le lit. La confluence tend à retrouver une morphologie semblable à celle qui prévalait avant la crue printanière.
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Cosmo, Roberto Di, and Delia Kesner. "Simulating expansions without expansions." Mathematical Structures in Computer Science 4, no. 3 (September 1994): 315–62. http://dx.doi.org/10.1017/s0960129500000505.
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We add extensional equalities for the functional and product types to the typed λ-calculus with, in addition to products and terminal object, sums and bounded recursion (a version of recursion that does not allow recursive calls of infinite length). We provide a confluent and strongly normalizing (thus decidable) rewriting system for the calculus that stays confluent when allowing unbounded recursion. To do this, we turn the extensional equalities into expansion rules, and not into contractions as is done traditionally. We first prove the calculus to be weakly confluent, which is a more complex and interesting task than for the usual λ-calculus. Then we provide an effective mechanism to simulate expansions without expansion rules, so that the strong normalization of the calculus can be derived from that of the underlying, traditional, non-extensional system. These results give us the confluence of the full calculus, but we also show how to deduce confluence directly form our simulation technique without using the weak confluence property.
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Kafle, Akinchan, Bidur Adhikari, Rajani Shrestha, and Nirju Ranjit. "Anatomic Variations of the Right Hepatic Duct: Results and Surgical Implications From a Cadaveric Study." Journal of Nepal Health Research Council 17, no. 01 (April 28, 2019): 90–93. http://dx.doi.org/10.33314/jnhrc.v17i01.2012.
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Background: Right hepatic duct, formed by the confluence of the anterior and posterior right sectorial ducts, joins left hepatic duct to form common hepatic duct. This fashion of confluence does not prevail in all cases. The sectorial ducts can aberrantly meet left duct and rest of the ducts from the left lobe of liver. Presence of such variation imposes clinical importance during peri-hilar, split liver transplant surgery or cholecystectomy. Nepalese population has not been explored before disregarding clinical necessity as MRI or cholangiography. Methods: Descriptive cross sectional study was conducted in 107 cases dissecting the main portal fissure separating hemi liver and extrahepatic biliary confluences. Methylene blue dye was injected and bile duct wall was cut open to the study pattern of the confluence. Data analysis was done with Statistical Package for Social Sciences (SPSS) version 17.Results: Normal variant of confluence was found in 72% cases, aberrant right posterior sectorial duct joins left hepatic duct in 9.3% and aberrant right anterior duct or low insertion of the right posterior sectorial duct was found in 1.9%. 9.3% of cases there is no true right hepatic duct often described as triple confluence. 0.9% cases showed no particular pattern of confluence where common hepatic duct is formed by multiple confluence. Quadrate lobe was found to be draining into right anterior sectorial duct in a single case.Conclusions: Right hepatic duct confluence pattern is variable and all the evidence occurs at the main portal fissure. Right sectorial duct may join the left duct avoiding normal confluence pattern. Right posterior sectorial duct may be inserted low in the common bile duct.Keywords: Duct; hepatic; sectorial; variation.
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Nelson, Heather B., and Hengli Tang. "Effect of Cell Growth on Hepatitis C Virus (HCV) Replication and a Mechanism of Cell Confluence-Based Inhibition of HCV RNA and Protein Expression." Journal of Virology 80, no. 3 (February 1, 2006): 1181–90. http://dx.doi.org/10.1128/jvi.80.3.1181-1190.2006.
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ABSTRACT An intimate relationship between hepatitis C virus (HCV) replication and the physiological state of the host liver cells has been reported. In particular, a highly reproducible and reversible inhibitory effect of high cell density on HCV replication was observed: high levels of HCV RNA and protein can be detected in actively growing cells but decline sharply when the replicon cells reach confluence. Arrested cell growth of confluent cells has been proposed to be responsible for the inhibitory effect. Indeed, other means of arresting cell growth have also been shown to inhibit HCV replication. Here, we report a detailed study of the effect of cell growth and confluence on HCV replication using a flow cytometry-based assay that is not biased against cytostasis and reduced cell number. Although we readily reproduced the inhibitory effect of cell confluence on HCV replication, we found no evidence of inhibition by serum starvation, which arrested cell growth as expected. In addition, we observed no inhibitory effect by agents that perturb the cell cycle. Instead, our results suggest that the reduced intracellular pools of nucleosides account for the suppression of HCV expression in confluent cells, possibly through the shutoff of the de novo nucleoside biosynthetic pathway when cells become confluent. Adding exogenous uridine and cytidine to the culture medium restored HCV replication and expression in confluent cells. These results suggest that cell growth arrest is not sufficient for HCV replicon inhibition and reveal a mechanism for HCV RNA inhibition by cell confluence.
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Pouchoulin, Sébastien, Emmanuel Mignot, Nicolas Rivière, and Jérôme Le Coz. "Numerical simulations on mixing of passive scalars in river confluences." E3S Web of Conferences 40 (2018): 05019. http://dx.doi.org/10.1051/e3sconf/20184005019.
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The study deals with the mixing of passive scalars (such as pollutants) in open-channel confluences when the two inflows exhibit different concentrations. The dispersion of such passive scalars is investigated through the analysis of the processes enhancing the mixing in the confluence in order to estimate the length for complete mixing Lm in the downstream branch. The aim of this study is then to establish a correlation between this length for complete mixing Lm and characteristics of the confluence, namely its angle and two hydrodynamic parameters that are the momentum ratio M* of the inflows and the width-to-depth ratio of the downstream branch b/h. In this work, the flow in the confluence is numerically simulated by RANS calculation coupled with the advection-diffusion equation at field scale, i.e. with Reynolds and Froude numbers corresponding to real rivers (Re = 107 and Fr=0.1). The role of other parameters such as bed discordance or bed forms... is not addressed here. The numerical results highlight that the mixing in the confluence and its downstream branch, is enhanced by the presence of secondary currents that are themselves strongly affected by the characteristics of the confluence. The results aim at getting an operative empirical law linking the geometric and hydrodynamic parameters of the confluence with Lm.
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Martone, Ivo, Carlo Gualtieri, and Theodore Endreny. "Characterization of Hyporheic Exchange Drivers and Patterns within a Low-Gradient, First-Order, River Confluence during Low and High Flow." Water 12, no. 3 (February 28, 2020): 649. http://dx.doi.org/10.3390/w12030649.
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Confluences are nodes in riverine networks characterized by complex three-dimensional changes in flow hydrodynamics and riverbed morphology, and are valued for important ecological functions. This physical complexity is often investigated within the water column or riverbed, while few studies have focused on hyporheic fluxes, which is the mixing of surface water and groundwater across the riverbed. This study aims to understand how hyporheic flux across the riverbed is organized by confluence physical drivers. Field investigations were carried out at a low gradient, headwater confluence between Baltimore Brook and Cold Brook in Marcellus, New York, USA. The study measured channel bathymetry, hydraulic permeability, and vertical temperature profiles, as indicators of the hyporheic exchange due to temperature gradients. Confluence geometry, hydrodynamics, and morphodynamics were found to significantly affect hyporheic exchange rate and patterns. Local scale bed morphology, such as the confluence scour hole and minor topographic irregularities, influenced the distribution of bed pressure head and the related patterns of downwelling/upwelling. Furthermore, classical back-to-back bend planform and the related secondary circulation probably affected hyporheic exchange patterns around the confluence shear layer. Finally, even variations in the hydrological conditions played a role on hyporheic fluxes modifying confluence planform, and, in turn, flow circulation patterns.
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Vestena, Leandro Redin, and Alessandro Kominecki. "Hidrogeomorfologia em confluência fluvial obtusa, Guarapuava, Paraná." Revista Brasileira de Geografia Física 14, no. 4 (2021): 2131–48. http://dx.doi.org/10.26848/rbgf.v14.4.p2131-2148.
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Solid and liquid mixtures in river courses intensify in areas of river confluence, conditioned mainly by the angular opening of the junction. Knowledge of hydrosedimentological dynamics in bedrock junctions with different angular openings is essential for understanding morphological adjustment at confluences and for supporting actions for the preservation and conservation of river ecosystems. For this reason, this article presents the results of a hydrogeomorphologic study on a river confluence with an obtuse junction angle (>100º), in a plateau bedrock river, in the Serra Geral Formation. The research evaluated a fluvial segment upstream and downstream of the Pedras River and in the Pombas River tributary, in Guarapuava, Paraná, through observations and measurements of morphological and hydraulic characteristics, width, talweg depth, bed declivity and bankfull flow. Morphological adjustment in obtuse confluences is peculiar in that the fluvial junction angle conditions specific flow, erosion, sediment transport and deposition dynamics, mainly resulting from its association with the geological nature of the river bed and types of land use and management upstream of the confluence.
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Lv, Xianli, and Zhongxue Wu. "Anatomic variations of internal jugular vein, inferior petrosal sinus and its confluence pattern: Implications in inferior petrosal sinus catheterization." Interventional Neuroradiology 21, no. 6 (September 16, 2015): 769–73. http://dx.doi.org/10.1177/1753425915590067.
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Objective The purpose of this study is to describe anatomic variations of the internal jugular vein (IJV), inferior petrosal sinus (IPS) and their confluence pattern and implications in IPS catheterization. The anatomic route of IPS after going out of the cranium and its confluence patterns with IJV and will supply knowledge about typing of IPS-IJV junction. Method A review of the literature was performed. Results There might be different routes for entering the intracranial segment of the IPS and multislice spiral computed tomography (MSCT) is effective in identifying the confluences of the IPS with the IJV and their courses. It is important to find the confluence of IPS with IJV for diagnosis and treatment of intracranial lesions via venous route. Meanwhile, IPS diameter at the confluence can significantly affect success of catheterization. Conclusion The classification and the theory of the development of the caudal end of the IPS may be useful in establishing treatment strategies that involve endovascular manipulation via the IPS.
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Chandler‐Olcott, Kelly, and Kathleen A. Hinchman. "Confluence." Journal of Adolescent & Adult Literacy 64, no. 4 (February 2021): 369–70. http://dx.doi.org/10.1002/jaal.1132.
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Gilliam, Angela M. "Confluence." Latin American Perspectives 41, no. 4 (March 4, 2014): 164–83. http://dx.doi.org/10.1177/0094582x14524362.
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Carr, David. "Confluence." Curator: The Museum Journal 51, no. 3 (July 2008): 241–51. http://dx.doi.org/10.1111/j.2151-6952.2008.tb00310.x.
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Soska, Tracy M., and Alice K. Johnson. "Confluence." Journal of Community Practice 12, no. 3-4 (December 2004): 243–48. http://dx.doi.org/10.1300/j125v12n03_15.
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Corso, Paola. "Confluence." International Feminist Journal of Politics 9, no. 4 (December 2007): 455–63. http://dx.doi.org/10.1080/14616740701607952.
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Quetchenbach, B. "Confluence." Interdisciplinary Studies in Literature and Environment 21, no. 4 (August 26, 2014): 906–21. http://dx.doi.org/10.1093/isle/isu090.
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K, Marianne. "Confluence." Scientific American 328, no. 5 (May 2023): 24. http://dx.doi.org/10.1038/scientificamerican0523-24.
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BAILLEUX, Anne, Dominique WENDUM, François AUDUBERT, Anne-Marie JOUNIAUX, Kamen KOUMANOV, Germain TRUGNAN, and Joëlle MASLIAH. "Cytosolic phospholipase A2-p11 interaction controls arachidonic acid release as a function of epithelial cell confluence." Biochemical Journal 378, no. 2 (March 1, 2004): 307–15. http://dx.doi.org/10.1042/bj20031014.
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Madin–Darby canine kidney type II cells were shown to release low amounts of AA (arachidonic acid) and prostaglandin E2 in response to various stimuli when analysed after cell confluence. In contrast, non-confluent Madin–Darby canine kidney type II cells released much higher amounts of AA and prostaglandin E2. In both stationary and non-confluent cells, AA was released by type IV cPLA2 (cytosolic phospholipase A2), as shown by the use of specific inhibitors and by analysis of the profile of fatty acids released. This confluence-dependent cPLA2 activation was not due to a difference in expression, or in phosphorylation of the enzyme, or in the amount of its substrate. To find out the mechanism by which cPLA2 activation may be regulated as a function of cell confluence, immunofluorescence and co-immunoprecipitation experiments were performed using cPLA2, p11, a natural inhibitor of the enzyme, and annexin II, the natural ligand of p11. These three proteins were expressed at a constant level, regardless of the cell confluence. In contrast, whereas annexin II and cPLA2 interacted at a constant rate, p11 and cPLA2 interacted more strongly in stationary cells, thus indicating that cPLA2 activation is regulated by its accessibility to p11, independent of their expression level. Our results indicate that, in epithelial cells, the cell confluence, i.e. the establishment of cell–cell contacts, rather than cell proliferation directly controls cPLA2 activation by changing the stoichiometry of p11/cPLA2 interaction.
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HAEMMERLÉ, RÉMY. "Diagrammatic confluence for Constraint Handling Rules." Theory and Practice of Logic Programming 12, no. 4-5 (July 2012): 737–53. http://dx.doi.org/10.1017/s1471068412000270.
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AbstractConfluence is a fundamental property of Constraint Handling Rules (CHR) since, as in other rewriting formalisms, it guarantees that the computations are not dependent on rule application order, and also because it implies the logical consistency of the program declarative view. In this paper we are concerned with proving the confluence of non-terminating CHR programs. For this purpose, we derive from van Oostrom's decreasing diagrams method a novel criterion on CHR critical pairs that generalizes all preexisting criteria. We subsequently improve on a result on the modularity of CHR confluence, which permits modular combinations of possibly non-terminating confluent programs, without loss of confluence.
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Liu, Alice, and Christopher J. Ng. "Quantitative analysis of Weibel-Palade bodies." PLOS ONE 17, no. 12 (December 21, 2022): e0278044. http://dx.doi.org/10.1371/journal.pone.0278044.
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Weibel Palade bodies (WPBs) are vesicles found in endothelial cells which carry the multimeric protein von Willebrand factor (VWF). As cellular confluency has been shown to influence the number of WPBs in endothelial cells, we propose to test two methods of attaining endothelial cell confluence to inform on the relevancy of cellular culture methods when analyzing endothelial WPBs. We test these cellular culture methods in two endothelial cell types, human umbilical vein endothelial cells (HUVECs) and endothelial colony forming cells (ECFCs). One method maintains a constant incubation time of 96 hrs. while varying the seeding density. The second method maintains a constant seeding density of 30,000 cells/cm2 while varying incubation time. In comparing these two methods, we evaluate the nuclei count, total WPB count, and WPB/nuclei count for each. Our results show that there is a trend of increasing nuclei count, total WPB count, and WPB/nuclei count as incubation time and seeding density increases. However, there is no difference in WPB/nuclei quantification whether confluency is reached via a constant seeding density or a constant incubation time. In addition, we show that confluency plays a major role in WPB/nuclei generation as we demonstrate higher WPB/nuclei counts in confluent cultures compared to sub-confluent cultures.
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Ishibe, Shuta, J. Erika Haydu, Akashi Togawa, Arnaud Marlier, and Lloyd G. Cantley. "Cell Confluence Regulates Hepatocyte Growth Factor-Stimulated Cell Morphogenesis in a β-Catenin-Dependent Manner." Molecular and Cellular Biology 26, no. 24 (October 9, 2006): 9232–43. http://dx.doi.org/10.1128/mcb.01312-06.
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ABSTRACT Following organ injury, morphogenic epithelial responses can vary depending on local cell density. In the present study, the role of cell confluence in determining the responsiveness of renal epithelial cells to the dedifferentiating morphogenic signals of hepatocyte growth factor (HGF) was examined. Increasing confluence resulted in a greater tendency of cells to organize into epithelial tubes and a significant decrease in migratory responsiveness to HGF. Analysis of downstream signaling revealed that the HGF receptor c-Met was equally activated in confluent and nonconfluent cells following HGF stimulation but that phosphoinositide 3-kinase-dependent activation of Akt and Rac were selectively diminished in confluent cells. In nonconfluent cells treated with HGF, the high level of Akt activation resulted in inhibitory phosphorylation of glycogen synthase kinase 3β (GSK-3β) and increased β-catenin nuclear signaling. In contrast, confluent cells, in which HGF-stimulated Akt activation was diminished, displayed less inhibitory phosphorylation of GSK-3β and less nuclear signaling by β-catenin. Overexpression of β-catenin (SA), which cannot be phosphorylated by GSK-3β and targeted for ubiquitination, significantly increased migration in fully confluent cells. Thus, cells maintained at high confluence selectively downregulate signaling events such as Rac activation and β-catenin-dependent transcription that would otherwise promote cell dedifferentiation and migration.
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Selokar, N. L., A. George, A. P. Saha, R. Sharma, M. Muzaffar, P. Palta, M. S. Chauhan, R. S. Manik, and S. K. Singla. "59 SYNCHRONIZATION OF CELL CYCLE STAGE OF BUFFALO (BUBALUS BUBALIS) FETAL FIBROBLAST CELLS BY DIFFERENT TREATMENTS." Reproduction, Fertility and Development 23, no. 1 (2011): 135. http://dx.doi.org/10.1071/rdv23n1ab59.
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Cell cycle stage of donor cells significantly influences the cloning efficiency during SCNT. Donor cells in G1/G0 stage have better capability to undergo nuclear reprogramming following transfer to an unfertilized oocyte. The lack of availability of cells synchronized at G1/G0 stage is one of the major factors limiting cloning efficiency in buffalo. The aim of this study was to compare the efficacy of various methods for cell cycle synchronization of buffalo fetal fibroblast cells for SCNT. Cells isolated from fetus, 2 to 3 months old, were cultured in DMEM + 10% FBS. The primary culture was sub-cultured 8 to 10 times. For cell cycle synchronization, the cells were cultured to 1) 60 to 70% confluence (controls), 2) 60 to 70% confluence followed by serum starvation (DMEM + 0.5% FBS) for 24 h (serum starved), 3), full confluence followed by culture for additional 3 to 5 days (full confluent), 4) full confluence followed by serum starvation (DMEM + 0.5% FBS) for 24 h (full confluent+serum starved) and 5) 60 to 70% confluence followed by treatment with roscovitine (10, 20, or 30 μM) for 24 h. The synchronization efficiency was examined by propidium iodide staining followed by analysis of DNA content using flow cytometry and the data were analysed by 1-way ANOVA followed by Fisher’s l.s.d. test after arcsine transformation. The percentage of cells in G0/G1 phase of cell cycle was significantly higher (P < 0.05) in the full confluent+serum starved and roscovitine treated (20 or 30 μM) groups than that in the full confluent group and that treated with 10 μM roscovitine which, in turn, was higher (P < 0.05) than that in the serum starved and control groups. These results suggest that buffalo fetal fibroblast cells can be synchronized by roscovitine treatment or by serum starvation of fully confluent cell cultures to obtain a high proportion of cells in G0/G1 stage for SCNT. Table 1.Buffalo skin fibroblast cells at various stages following different treatments for cell cycle synchronization Supported by grant No. 1(5)/2007-NAIP from ICAR, India.
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Rao, M. R. K. Krishna. "Relating confluence, innermost-confluence and outermost-confluence properties of term rewriting systems." Acta Informatica 33, no. 5 (August 1996): 595–606. http://dx.doi.org/10.1007/bf03036465.
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Krishna Rao, M. R. K. "Relating confluence, innermost-confluence and outermost-confluence properties of term rewriting systems." Acta Informatica 33, no. 6 (September 1, 1996): 595–606. http://dx.doi.org/10.1007/s002360050060.
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Imhoff, K. S., and A. C. Wilcox. "Coarse bedload routing and dispersion through tributary confluences." Earth Surface Dynamics Discussions 3, no. 4 (December 17, 2015): 1509–53. http://dx.doi.org/10.5194/esurfd-3-1509-2015.
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Abstract. Sediment routing fundamentally influences channel morphology and propagation of disturbances. However, the transport and storage of bedload particles in headwater channel confluences, which may be significant nodes of the channel network in terms of sediment routing, morphology, and habitat, is poorly understood. To characterize routing processes through confluences of headwater channels, we investigate how sediment routing patterns through headwater confluences compare to those described in low-gradient gravel bed river systems, and how confluences affect the dispersive behavior of coarse bedload particles compared to non-confluence reaches. We address these questions with a field tracer experiment using passive-integrated transponder and radio-frequency identification technology in the East Fork Bitterroot River basin, Montana, USA. Within the confluence zone, transport occurs along scour hole margins in narrow, efficient transport corridors that mirror those observed in finer-grained experiments and field studies. Coarse particles entering confluences experience reduced depositional probabilities, in contrast to the size-selective transport observed in a control reach. Stochastic transport modeling, tail analysis, and use of a dimensionless impulse (I&ast;) suggest that transport distance and variance growth are enhanced through confluences for a given flow strength. We suggest that confluences absent of disturbances enhance sediment transport and dispersive growth through headwater networks.
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Gazi, Md Yousuf, Himel Roy, Md Bodruddoza Mia, and Syed Humayun Akhter. "Assessment of Morpho-Dynamics through Geospatial Techniques within the Padma-Meghna and Ganges-Jamuna River Confluences, Bangladesh." KN - Journal of Cartography and Geographic Information 70, no. 3 (September 2020): 127–39. http://dx.doi.org/10.1007/s42489-020-00051-2.
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Abstract Bangladesh is a low-lying riverine country with the mighty Ganges–Brahmaputra–Meghna (GBM) major river system including their abundant tributaries and distributaries. Land erosion–accretion is a very common phenomenon in this riverine country. This process extensively erodes huge productive landmasses at the river confluence zones every year. The main objective of this study was to understand the confluence morpho-dynamics and identify the vulnerable areas near the Padma–Meghna Confluence (PMC) and Ganges–Jamuna confluence (GJC) due to confluence shifting and erosion–accretion phenomenon of those rivers. The present study utilized multi-temporal Landsat satellite images from 1972 to 2019 approximately ten years of interval. Results showed that the PMC indicated frequent variation in migration trend towards NW from 1972 to 1980, SE from 1980 to 2010, and then reversed towards NW direction from 2010 to 2019. On the other hand, the GJC confluence point moved NW direction (2.37 km) from the year 1972 to 1980, but from 1980 to 2019, the confluence shifted towards the SE direction. Due to the migration dynamics, huge changes happened in width and sand bars area of both confluences. In PMC, confluence width increased remarkably indicating erosive flow during 1972–1980, then progressively shortened up to 2019, indicating accretion. In contrast, GJC shows a significant accretional trend over the 47 years. The sand bar area of the PMC increased about 147.09 km2 throughout the study period. But, GJC shows an opposite scenario where the total sand bar area decreased about 51.02 km2 in the same period. From the vulnerability study of erosion–accretion scenarios, it is predicted that Paturia Ferry Ghat area, Aricha Ferry Ghat area, Arua, Baruria, Dashkin Saljana, Bhadiakola, Masundia, Khanganj and Nyakandi areas near GJC and Chandpur sadar, Srimandi, Sakhua, Bilaspur and char Atra near PMC are highly vulnerable zones. The outputs of the study will enable policy makers to take necessary measures to reduce the erosional severity on both confluence zones and could also provide a basis for proper land management.
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Unde, Maya G., and Subash Dhakal. "Sediment characteristics at river confluences: a case study of the Mula-Kas confluence, Maharashtra, India." Progress in Physical Geography: Earth and Environment 33, no. 2 (April 2009): 208–23. http://dx.doi.org/10.1177/0309133309338655.
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River bed and floodplain sediments are a direct reflection of river channel processes. This paper examines sediment transfer processes at river junctions, using as a case study the River Kas, a tributary of the River Mula, Godavari basin, Maharashtra, India. The study uses four cross-sections, two from upstream tributaries, one in the main confluence zone, and one downstream. Sediment samples are collected from each cross-section and adjacent banks. To understand the tributary impact on the main channel, variations in sand, silt and clay percentages and variations in the shape of sediment particles were recorded. Data suggest that the percentage of silt and clay increased away from the active channel towards banks along a cross-section, except for the mid-channel bar and the downstream segment of the confluence. The `a axis' and `c axis' lengths of particles increased for the samples on the confluence compared to upstream and downstream samples. Sediment characteristics between tributary and the main stream reflect both downstream distance from sediment source and the characteristics of the respective transport processes. The distribution of fine material at the tributary mouth suggests that there have been instances in the past where the mainstream flow has dominated the confluence and has led to slack water deposits on the tributary mouth. Construction of a weir for local flow regulation also affects the pattern and character of sediments. In this large, seasonal river, confluence sedimentology is a joint product of flow variation, confluence morphology and the additional effects of human activity. The study thus provides insights into confluence dynamics and characteristics which may not be revealed in the more intensively researched temperate confluences of smaller scale.
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Ofori, Jones K., Helena A. Malm, Ines G. Mollet, Lena Eliasson, and Jonathan Lou S. Esguerra. "Confluence does not affect the expression of miR-375 and its direct targets in rat and human insulin-secreting cell lines." PeerJ 5 (June 28, 2017): e3503. http://dx.doi.org/10.7717/peerj.3503.
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MicroRNAs are small non-coding RNAs, which negatively regulate the expression of target genes. They have emerged as important modulators in beta cell compensation upon increased metabolic demand, failure of which leads to reduced insulin secretion and type 2 diabetes. To elucidate the function of miRNAs in beta cells, insulin-secreting cell lines, such as the rat insulinoma INS-1 832/13 and the human EndoC-βH1, are widely used. Previous studies in the cancer field have suggested that miRNA expression is influenced by confluency of adherent cells. We therefore aimed to investigate whether one of the most enriched miRNAs in the pancreatic endocrine cells, miR-375, and two of its validated targets in mouse, Cav1 and Aifm1, were differentially-expressed in cell cultures with different confluences. Additionally, we measured the expression of other miRNAs, such as miR-152, miR-130a, miR-132, miR-212 and miR-200a, with known roles in beta cell function. We did not see any significant expression changes of miR-375 nor any of the two targets, in both the rat and human beta cell lines at different confluences. Interestingly, among the other miRNAs measured, the expression of miR-132 and miR-212 positively correlated with confluence, but only in the INS-1 832/13 cells. Our results show that the expression of miR-375 and other miRNAs with known roles in beta cell function is independent of, or at least minimally influenced by the density of proliferating adherent cells, especially within the confluence range optimal for functional assays to elucidate miRNA-dependent regulatory mechanisms in the beta cell.
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Chen, Xue, David Z. Zhu, and Peter M. Steffler. "Secondary currents induced mixing at channel confluences." Canadian Journal of Civil Engineering 44, no. 12 (December 2017): 1071–83. http://dx.doi.org/10.1139/cjce-2016-0228.
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Channel confluence is a common feature in river systems. The flow dynamics associated with channel confluence are highly three-dimensional with strong flow circulations and secondary currents and can result in enhanced river mixing downstream. In this study, a three-dimensional numerical model was employed to estimate the secondary currents induced streamline curvatures and the resulting mixing rate at channel confluences with different junction angles and discharge ratios. The results show that while twin secondary circulations are found at channel confluence, their contribution to the mixing depends on their local positions with respect to the river streams. With the secondary current growing downstream, the mixing rate is accelerated, in particular for the cases with the side channel perpendicular to the main channel and having a relatively large discharge. Turbulent diffusion can contribute up to about half of the rapid mixing. The mixing rates for different simulation cases are examined.
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Martin-Moreta, Pedro, Susana Lopez-Querol, and Juan P. Martín-Vide. "Sediment Transport Capacity in a Gravel-Bed River with a Sandy Tributary." CivilEng 4, no. 4 (November 30, 2023): 1214–32. http://dx.doi.org/10.3390/civileng4040067.
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Bedload transport in a river is a deeply analyzed problem, with many methodologies available in the literature. However, most of the existing methods were developed for reaches of rivers rather than for confluences and are suitable for a particular type of material, which makes them very inaccurate in cases where the sediments are comprised of a mix of different types of soil. This study considers the effect of two different bed sediment sizes, gravel and sand, in relation to bed load transport in a confluence. Five well-known and validated equations (namely Meyer-Peter and Müller, Parker + Engelund and Hansen, Ackers and White, and Yang) are applied to the case study of the Tagus–Alberche rivers confluence (in Talavera de la Reina, Spain), where main and tributary rivers transport different materials (sand and gravel). Field works in the area of the confluence were conducted, and a set of alluvial samples were collected and analyzed. The previously mentioned methods were employed to analyze the geomorphology in the confluence area and downstream of it under different flooding scenarios, concluding different trends in terms of deposition/erosion in the area under historic flooding scenarios. When the trends show erosion, all methods are very consistent in terms of numerical predictions. However, the results present high disparity in the estimated values when the predictions suggest deposition, with Parker + Engelund and Hansen yielding the highest volumes and Meyer-Peter and Müller the lowest (the latter being around 1% of the former). Yang and Ackers and White predict deposits in the same range in all cases (around 15% of Parker and Engelund Hansen). Yang’s formula was found to be suitable for the confluences of rivers with different materials, allowing for the estimation of sediment transport for different grain sizes. The effect of different flow regimes has been analyzed with the application of Yang’s formula to the Tagus-Alberche confluence.
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Thornbrugh, Darren J., and Keith B. Gido. "Influence of spatial positioning within stream networks on fish assemblage structure in the Kansas River basin, USA." Canadian Journal of Fisheries and Aquatic Sciences 67, no. 1 (January 2010): 143–56. http://dx.doi.org/10.1139/f09-169.
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We found that riverine confluences had localized effects (within 20 km) on stream fish assemblages of the Kansas River basin. The majority of variation in fish assemblages occurred from east to west and along a stream size gradient. After controlling for the influences of longitude and stream size, distance of sample sites from streams ≥ 5th order accounted for a small proportion of taxonomic variability. However, species richness was significantly higher and assemblage structure was different in tributary stream segments directly connected to larger-ordered streams, suggesting that the effects of spatial position within this stream network were greatest in close proximity to tributary–mainstem confluences. Fish collections from three intensively sampled tributaries also indicated an abrupt change in species assemblages between mainstem river sites and tributary sample sites above confluences, followed by a gradual taxonomic change with increasing distance up to 20 km from the confluence. Changes in fish assemblages were associated with the reduced abundance of adult stream species near the confluence with the mainstem, rather than the occurrences of riverine species in the tributary.
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Wooffitt, Robin. "Poetic confluence." Journal of Anomalous Experience and Cognition 2, no. 1 (May 13, 2022): 80–110. http://dx.doi.org/10.31156/jaex.23818.
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This paper is an exploratory sociological analysis of poetic confluence, a spontaneous telepathic phenomenon that occurs in everyday social interaction. In poetic confluence, one person’s talk exhibits an enigmatic relationship to another’s unstated thoughts or imagery at that moment. The analyses draw from an empirical approach called Conversation Analysis, a formal qualitative method for the analysis of naturally occurring interaction in everyday life. In Conversation Analysis, talk-in-interaction is analyzed as coordinated and sequentially organized action. The focus on the action orientation of talk informs this analysis, treating poetic confluence as a form of social action. The data are (unavoidably) anecdotal accounts of experiences. Although the techniques of Conversation Analysis cannot be applied to anecdotal reports, its methodological principles and substantive focus can inform a systematic analysis of anecdotal data. A case is made for the robustness of poetic confluence via analysis of recurrent properties found in examples from three corpora of candidate cases. The analysis identifies three interpersonal functions of poetic confluence: its role in restoring mutual attention; its affiliative, affective function; and its role as a mechanism for managing threats to social propriety, or keeping “face.” In the discussion, alternative skeptical explanations are assessed; the empirical approach is framed in terms of Cardeña’s (2019) observations on the metaphoric quality of some psi phenomena and Carpenter’s (2012) first sight theory, and some suggestions are offered for further research on social interaction and psi phenomena.
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Omhovère, Claire. "Confluence. Introduction." Commonwealth Essays and Studies 40, no. 2 (April 1, 2018): 5–7. http://dx.doi.org/10.4000/ces.279.
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Smith, Edward W. L. "Exploring Confluence." Journal of Couples Therapy 1, no. 1 (June 20, 1990): 21–28. http://dx.doi.org/10.1300/j036v01n01_03.
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Burt, SusanMeredith. "Maxim confluence." Journal of Pragmatics 34, no. 8 (August 2002): 993–1001. http://dx.doi.org/10.1016/s0378-2166(01)00041-8.
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Liu, Xiaodong, Lingqi Li, Zulin Hua, Qile Tu, Ting Yang, and Yuan Zhang. "Flow Dynamics and Contaminant Transport in Y-Shaped River Channel Confluences." International Journal of Environmental Research and Public Health 16, no. 4 (February 16, 2019): 572. http://dx.doi.org/10.3390/ijerph16040572.
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River channel confluences are widespread in natural rivers. Understanding their unique hydrodynamic characteristics and contaminant transport rules may facilitate the rational and effective treatment of the water environment. In this study, we considered the Xitiaoxi River Basin as the research area, and a well-designed flume was established based on the extracted water system features. Hydrodynamically, in the Y-shaped confluence channel the flow velocity was easy to separate at the confluence, and a low flow velocity region appeared in the two branches. The spiral flow mainly flowed counterclockwise to the downstream region and the spiral trend increased as the discharge ratio decreased. The spiral flow and its effect on the transport and blending of contaminants were distinct between Y-shaped and asymmetrical river confluences. Based on the flow dynamics test, a set of pollutant discharge devices and a multi-point electrolytic conductivity meter were employed to research the mixing rule for pollutants. A high concentration zone for pollutants was likely to occur near the intersection, and the contaminant concentration band after the confluence was first compressed and then diffused. In particular, line source discharge in the left branch and the point source discharge in the inner bank of the left branch and in the outer bank of the right branch were dominant, and were conducive to the detection and treatment of pollutants.
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Barbeau, Solène, Alexandre Joushomme, Yann Chappe, Guillaume Cardouat, Isabelle Baudrimont, Véronique Freund-Michel, Christelle Guibert, et al. "Cell Confluence Modulates TRPV4 Channel Activity in Response to Hypoxia." Biomolecules 12, no. 7 (July 7, 2022): 954. http://dx.doi.org/10.3390/biom12070954.
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Transient receptor potential vanilloid 4 (TRPV4) is a polymodal Ca2+-permeable channel involved in various hypoxia-sensitive pathophysiological phenomena. Different tools are available to study channel activity, requiring cells to be cultured at specific optimal densities. In the present study, we examined if cell density may influence the effect of hypoxia on TRPV4 activity. Transiently TRPV4-transfected HEK293T cells were seeded at low or high densities corresponding to non-confluent or confluent cells, respectively, on the day of experiments, and cultured under in vitro normoxia or hypoxia. TRPV4-mediated cytosolic Ca2+ responses, single-channel currents, and Ca2+ influx through the channel were measured using Ca2+ imaging/microspectrofluorimetric assay, patch-clamp, and Bioluminescence Resonance Energy Transfer (BRET), respectively. TRPV4 plasma membrane translocation was studied using confocal microscopy, biotinylation of cell surface proteins, and BRET. Our results show that hypoxia exposure has a differential effect on TRPV4 activation depending on cell confluence. At low confluence levels, TRPV4 response is increased in hypoxia, whereas at high confluence levels, TRPV4 response is strongly inhibited, due to channel internalization. Thus, cell density appears to be a crucial parameter for TRPV4 channel activity.
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MIZUSHIMA, J., and Y. KAWAGUCHI. "Transitions of flow past a row of square bars." Journal of Fluid Mechanics 405 (February 25, 2000): 305–23. http://dx.doi.org/10.1017/s0022112099007399.
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Transitions of flow past a row of square bars placed across a uniform flow are investigated by numerical simulations and the bifurcation analysis of the numerical results. The flow is assumed two-dimensional and incompressible. It is already known that jets coming through gaps between square bars are independent of each other when the pitch-to-side-length ratio of the row is large, whereas the confluence of two or three jets occurs due to a first pitchfork bifurcation from the flow with independent jets when the pitch-to-side-length ratio is small. It is found that confluence of four jets occurs in consequence of the second pitchfork bifurcation from the flow with pairs of jets joined to each other. Bifurcation diagrams of the flow are obtained, which include confluences of double, triple and quadruple jets. Lengths of the twin vortices are evaluated for each flow pattern. The confluences of two, three and four jets are qualitatively confirmed experimentally by flow visualizations.
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Sasak, W. V., H. A. Buller, and R. Reinhold. "Biosynthetic precursor (214 kDa) of apolipoprotein B-48 is not secreted by Caco-2 cells and normal human intestine." Biochemical Journal 264, no. 2 (December 1, 1989): 365–70. http://dx.doi.org/10.1042/bj2640365.
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The synthesis and secretion of apolipoprotein B (apo B) was studied in a human colon carcinoma (Caco-2) cell line and in explants from normal human intestine. In Caco-2 cells, the specific activity of the intestinal disaccharidases maltase, sucrase-isomaltase and lactase was enhanced 8-, 6- and 3-fold respectively, at 19 days post-confluence as compared with 1-day-post-confluence cultures. The level of apo B secreted into the medium increased from undetectable in the cells just reaching confluency, to 115 ng/ml at 18 days post-confluence. The presence of apo B-100 and apo B-48 with mobilities on SDS/polyacrylamide-gel electrophoresis corresponding to those of human very-low-density lipoproteins and lymph chylomicrons, respectively, was detected in the media from 7-, 12- and 18-days-post-confluence cells. These two apo B proteins were also found intracellularly in 7-day-post-confluence cultures. However, more differentiated cells (12 and 18 days post-confluence) accumulated large amount of a 214 kDa protein intracellularly. Apo B-related 214 kDa protein was also synthesized by normal human intestinal explants. A pulse-chase experiment with explants from normal human jejunum showed a slow intracellular conversion of the 214 kDa protein into the size of mature apo B-48 (264 kDa), concomitant with increasing amounts of mature apo B-48 in the medium, suggesting a precursor-product relationship. Despite large intracellular quantities, the 214 kDa protein from the normal human tissue and Caco-2 cells was absent from the medium. No apo B-100 synthesis was detected in the human explants. These findings may help in our understanding of cholesterol and lipid metabolism in health and in some disorders characterized by the inability to secrete apo B-containing lipoproteins.
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Wang, Bo, Y. Jun Xu, Wei Xu, Heqin Cheng, Zhongyuan Chen, and Weiguo Zhang. "Riverbed Changes of the Uppermost Atchafalaya River, USA—A Case Study of Channel Dynamics in Large Man-Controlled Alluvial River Confluences." Water 12, no. 8 (July 29, 2020): 2139. http://dx.doi.org/10.3390/w12082139.
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River confluences are important nodes for downstream sediment transport and geomorphological development. Previous studies have established the knowledge that under natural conditions, river confluence zones experience channel scour followed with middle channel bar development. Less care is however given to the intensity of a confluence scour zone under man-controlled conditions, such as discharge regulation and levee confinement. In general, our knowledge about long-term bed evolution downstream of large alluvial river confluences is limited. Here we conducted a study focused on the 69-km uppermost channel of the Atchafalaya River, the largest distributary of the Mississippi River, to test the hypothesis that the channel downstream of two large tributaries sustains longer-term, extensive bed scouring owing to increased discharge in the main channel and, therefore, mid-channel bars in such a confluence zone cannot be built under confined channel conditions. The Atchafalaya River carries the total flow from the Red River and approximately 25% of the Mississippi River flow, traveling southwards 230 km before emptying into the Gulf of Mexico. We utilized long-term records on water surface elevation and discharge during 1935–2016, as well as channel bathymetry survey data during 1998–2006 to determine changes in hydraulic head and morphologic deformation in the confluence zone. The results from this study show that the combined flow from the Red River and Mississippi River into the Atchafalaya River steadily increased to approximately 5848 cubic meters per second (m3 s−1) in the recent decades, and the channel bed of the uppermost Atchafalaya River experienced considerable erosion since the 1930s. At a specific discharge of 8000 ± 100 m3 s−1, the river stage decreased by 5.8, 5.6, and 4.9 m from 1935 to 2016 at (from upstream to downstream) Simmesport, Melville, and Krotz Springs gauging stations, respectively. The average bed elevation reduced by 1.9 m from 1998 to 2006, although its thalweg increased by 0.3 m. Based on the channel bed assessment, a total volume of 6.6 × 107 m3 sediment was eroded from the uppermost 69 km of the Atchafalaya over the 8 years. The findings suggest that confluence zones of large alluvial rivers under controlled flow and confined levee conditions can experience extensive, long-lasting channel erosion. This can be especially progressive if the channel below a confluence is confined by levees, which can increase drag forces and prevent middle channel deposition. Further studies are needed to determine if the eroded sediment from the uppermost Atchafalaya is carried out to the river mouth or is deposited in the lower Atchafalaya. Such knowledge will have both scientific and practical relevance in river engineering and management.
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Villers Ruis, Lourdes. "El impacto de los proyectos sectoriales sobre el ambiente en la República Mexicana." Estudios Geográficos 53, no. 206 (April 30, 1992): 199–212. http://dx.doi.org/10.3989/egeogr.1992.i206.199.
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Se presentan los resultados globales de la evaluación de 288 proyectos de seis sectores productivos en el país, para ser realizados en la presente administración federal ( 1990-94). El análisis se realizó sobre las afecciones ambientales que causan los proyectos particulares de los diferentes sectores productivos, así como las áreas territoriales más afectadas por confluencia de proyectos. Se definieron cinco áreas críticas por confluencia de proyectos y por la magnitud de las afectaciones.
[fr] Présentation des resultats généraux de l'évaluation de 288 projets de six secteurs productifs visant a etre réalisés sous l'administration fédérale de la période 1990-94. L'analyse qui a été faite concerne l'impact des projets particuliers des differents secteurs productifs sur l'environnement, ainsi que les conséquences de la confluence des projets sus des territoires specifiques. Cinq aires critiques ont été repérées selon la confluence des projets et l'importance des impacta.
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Barbee, Kenneth A. "Changes in surface topography in endothelial monolayers with time at confluence: influence on subcellular shear stress distribution due to flow." Biochemistry and Cell Biology 73, no. 7-8 (July 1, 1995): 501–5. http://dx.doi.org/10.1139/o95-055.
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It is well known that the morphology of endothelial cells in culture changes dramatically as they go from subconfluence to confluence. After reaching confluence, however, the morphology continues to change but much more subtly as cell density increases and they become more uniform in size and shape. Measurements of surface topography of confluent cells by atomic force microscopy (AFM) showed that cell heights became more uniform and that the root-mean-square amplitude of surface undulations decreased by 7% compared with monolayers that had just reached confluence. Computational fluid dynamics simulations of flow over the endothelial surface geometries measured by AFM showed that the change in topography with time after confluence altered the shear stress distribution, resulting in an increase in the stress concentrations experienced by the cells despite the reduced amplitude of the surface undulation. These data suggest that the starting point for in vitro experiments may influence the measured responses to shear stress, particularly transient responses that occur before structural adaptation takes place. In addition, changes in surface topography may reflect changes in cell tension, cytoskeletal structure, and adhesion to the substratum, all of which are associated with the regulation of growth in anchorage-dependent cells.Key words: cell mechanics, mechanotransduction, cell structure, cell culture.
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Chen, W. Y., M. E. Grant, A. M. Schor, and S. L. Schor. "Differences between adult and foetal fibroblasts in the regulation of hyaluronate synthesis: correlation with migratory activity." Journal of Cell Science 94, no. 3 (November 1, 1989): 577–84. http://dx.doi.org/10.1242/jcs.94.3.577.
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We have previously reported that confluent foetal fibroblasts migrate into three-dimensional collagen gel matrices to a significantly greater extent than do adult cells. Hyaluronic acid (HA) is a major constituent of the extracellular matrix deposited by fibroblasts and has been demonstrated to stimulate the migration of a number of different cell types. Previous studies have indicated that the synthesis of HA by normal adult skin fibroblasts declines significantly when the cells achieve confluence. Data presented in this paper indicate that foetal fibroblasts differ from adult cells in this respect, in that they do not show an inverse relationship between cell density and HA synthesis, i.e. confluent foetal fibroblasts continue to produce approximately the same amount of HA as do subconfluent cells. These data suggest that the synthesis of relatively high levels of HA by foetal fibroblasts at confluence may be causally related to the elevated migration displayed by these cells. In this context, a close correlation was observed between the level of HA synthesized by confluent foetal and adult fibroblasts and the differential migratory activity displayed by these cells. Such differences in HA synthesis and migratory behaviour were only apparent at cell confluence, with subconfluent foetal and adult fibroblasts being indistinguishable in terms of these two criteria. Our data further reveal that: (1) cell density affects the size class of HA synthesized by both foetal and adult cells; and that (2) there is a considerable degree of heterogeneity amongst the nine different fibroblast lines examined in this study in terms of the size class of HA that they produce.
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Khosravinia, Payam, Amir Malekpour, Mohammad Reza Nikpour, and Ali Hosseinzadeh Dalir. "Scour depth in confluences considering tributary flow, bank slope, and post-confluence conditions." Water Supply 20, no. 6 (June 24, 2020): 2389–99. http://dx.doi.org/10.2166/ws.2020.131.
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Abstract In this paper, scouring in confluences was experimentally studied considering the effects of bank slope angle (θ) of the main channel, discharge ratio (Qr) of tributary channel and densimetric Froude number (Frg3) of the post-confluence channel. The experiments were conducted using a constant confluence angle (α) equal to 90° and various bank slope angles of 45°, 60°, 75° and 90°. Applying different Qr and Frg3, the maximum effect of θ on scour depth was observed when the minor Qr was used in the tributary channel. The mildest bank slope angle caused the minimum scour depth for any given Frg3. Generally, the experiment using θ = 45° and Qr = 0.194 showed the best performance and reduced the maximum scour depth by 46%. Considering two obtained empirical relationships, it was concluded that the effect of θ on the height of the point bar is more than its effect on the scour depth. Finally, Frg3 and θ demonstrated their greatest influences on dimensionless scour depth (dse/y3) and dimensionless height of point bar (Hse/B3), respectively.
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Li, C. X., and M. J. Poznansky. "Characterization of the ZO-1 protein in endothelial and other cell lines." Journal of Cell Science 97, no. 2 (October 1, 1990): 231–37. http://dx.doi.org/10.1242/jcs.97.2.231.
Full textAbstract:
A high molecular weight tight junction-associated protein, ZO-1, has been demonstrated in liver (hepatocytes) and in both epithelium and endothelium. We carried out studies to examine the presence of the protein in vascular endothelial cell cultures and several other types of cultured cells, and the relationship between the ZO-1 protein content and confluency of endothelial cell monolayers. Immunofluorescence labelling of endothelial monolayers and two types of epithelial monolayers, IEC-6 and MDCK, with monoclonal antibody against ZO-1 protein localized the protein to the cell peripheries. Its association with the cell periphery only occurred when cells had contact with one another as demonstrated in endothelial cells. We have been able to show a positive correlation between the ZO-1 content of the cells and the extent of monolayer confluency in the endothelial cells by immunoblotting. The protein is much less expressed in nonconfluent endothelial cell monolayers and totally absent from mouse myeloma cultures. The presence and confluence-related expression of the protein in endothelium give support to the hypothesis that tight junctions exist in confluent endothelial cells and that the ZO-1 protein is expressed under the conditions where tight junction interactions occur.