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Search Results: 1 - 10 of 202199 matches for " P. Raphael "
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Stable blow up dynamics for the critical co-rotational Wave Maps and equivariant Yang-Mills problems
P. Raphael,I. Rodnianski
Mathematics , 2009,
Abstract: We exhibit stable finite time blow up regimes for the energy critical co-rotational Wave Map with the S^2 target in all homotopy classes and for the critical equivariant SO(4) Yang-Mills problem. We derive sharp asymptotics on the dynamics at the blow up time and prove quantization of the energy focused at the singularity.
Cross-Correlation of Station-to-Station Free Surface Elevation Time Series for Breaking Water Waves  [PDF]
Raphael Mukaro
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.92010
Abstract:
Free surface elevation time series of breaking water waves were measured in a laboratory flume. This was done in order to analyze changes in wave characteristics as the waves propagated from deep water to the shore. A pair of parallel- wire capacitive wave gages was used to simultaneously measure free surface elevations at different positions along the flume. One gage was kept fixed near the wave generator to provide a reference while the other was moved in steps of 0.1 m in the vicinity of the break point. Data from these two wave gages measured at the same time constitute station-to-station free surface elevation time series. Fast Fourier Transform (FFT) based cross-correlation techniques were employed to determine the time lag between each pair of the time series. The time lag was used to compute the phase shift between the reference wave gage and that at various points along the flume. Phase differences between two points spaced 0.1 m apart were used to calculate local mean wave phase velocity for a point that lies in the middle. Results show that moving from deep water to shallow water, the measured mean phase velocity decreases almost linearly from about 1.75 m/s to about 1.50 m/s at the break point. Just after the break point, wave phase velocity abruptly increases to a maximum value of 1.87 m/s observed at a position 30 cm downstream of the break point. Thereafter, the phase velocity decreases, reaching a minimum of about 1.30 m/s.
Greedy Polyominoes and first-passage times on random Voronoi tilings
Leandro P. R. Pimentel,Raphael Rossignol
Mathematics , 2008,
Abstract: Let N be distributed as a Poisson random set on R^d with intensity comparable to the Lebesgue measure. Consider the Voronoi tiling of R^d, (C_v)_{v\in N}, where C_v is composed by points x in R^d that are closer to v than to any other v' in N. A polyomino P of size n is a connected union (in the usual R^d topological sense) of n tiles, and we denote by Pi_n the collection of all polyominos P of size n containing the origin. Assume that the weight of a Voronoi tile C_v is given by F(C_v), where F is a nonnegative functional on Voronoi tiles. In this paper we investigate the tail behavior of the maximal weight among polyominoes in Pi_n for some functionals F, mainly when F(C_v) is the number of faces of C_v. Next we apply our results to study self-avoiding paths, first-passage percolation models and the stabbing number on the dual graph, named the Delaunay triangulation. As the main application we show that first passage percolation has at most linear variance.
Decision Trees as a Tool to Select Sugarcane Families  [PDF]
Luiz A. Peternelli, Diego P. Bernardes, Bruno P. Brasileiro, Marcio H.P. Barbosa, Raphael H. T. Silva
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.92018
Abstract: New strategies are required in the sugarcane selection process to optimize the genetic gains in breeding programs. Conventional selection strategies have the disadvantage of requiring the weighing of all the plants in a plot or a sample of stalks and the counting of the number of stalks in all the experimental plots, which cannot always be performed because more than 200,000 genotypes routinely comprise the first test phase (T1) of most sugarcane breeding programs. One way to circumvent this problem is to use decision trees to rank the yield components (the stalk height, the stalk diameter and the number of stalks) and to subsequently use this categorization to select the best families for a specific trait. The objective of this study was to evaluate the categorization of yield components using the classification and regression tree (CART) algorithm as a family selection strategy by comparing the performance of CART with those of conventional methods that require the weighing of stalks, such as the best linear unbiased prediction (BLUP) with sequential (BLUPS) or individual simulated (BLUPIS) procedures. Data from five experiments performed in May 2007 in a randomized block design were analyzed. Each experiment consisted of five blocks, 22 families and two controls (commercial varieties). CART effectively defined the classes of the yield components and selected the best families with an accuracy of 74% compared to BLUPS and BLUPIS. Families with at least 11 stalks per linear meter of furrow resulted in productivities that were above the average productivity of the commercial varieties used in this study and are, therefore, recommended for selection.
Optimization of an Ammonia Synthesis Converter  [PDF]
Jackson Gunorubon Akpa, Nwokoma Raphael Raphael
World Journal of Engineering and Technology (WJET) , 2014, DOI: 10.4236/wjet.2014.24032
Abstract: A scheme that optimizes the converter of an ammonia synthesis plant to determine optimal inlet temperatures of the catalyst beds has been developed. The optimizer maximizes an objective function—The fractional conversion of nitrogen on the four catalyst beds of the converter subject to variation of the inlet temperature to each catalyst bed. An iterative procedure was used to update the initial values of inlet temperature thus ensuring accurate results and quick convergence. Converter model results obtained with optimized operating conditions showed significant increase in fractional conversion of 42.38% (from 0.1949 to 0.2586), increased rate of reaction evident in a 13.18% (0.5317 to 0.4616) and 23.84% (0.1946 to 0.1482) reduction in reactants (hydrogen and nitrogen) concentration respectively and a 56.48% increase (from 0.1181 to 0.1838) in ammonia concentration at the end of the fourth catalyst bed compared to results obtained with industrial operating conditions.
Compartmentalization of Aquaporins in the Human Intestine
Hari H. P. Cohly,Raphael Isokpehi,Rajendram V. Rajnarayanan
International Journal of Environmental Research and Public Health , 2008, DOI: 10.3390/ijerph5020115
Abstract: Improper localization of water channel proteins called aquaporins (AQP) induce mucosal injury which is implicated in Crohn’s disease and ulcerative colitis. The amino acid sequences of AQP3 and AQP10 are 79% similar and belong to the mammalian aquaglyceroporin subfamily. AQP10 is localized on the apical compartment of the intestinal epithelium called the glycocalyx while AQP3 is selectively targeted to the basolateral membrane. Despite the high sequence similarity and evolutionary relatedness, the molecular mechanism involved in the polarity, selective targeting and function of AQP3 and AQP10 in the intestine is largely unknown. Our hypothesis is that the differential polarity and selective targeting of AQP3 and AQP10 in the intestinal epithelial cells is influenced by amino acid signal motifs. We performed sequence and structural alignments to determine differences in signals for localization and posttranslational glycosylation. The basolateral sorting motif “YRLL” is present in AQP3 but absent in AQP10; while Nglycosylation signals are present in AQP10 but absent in AQP3. Furthermore, the C-terminal region of AQP3 is longer compared to AQP10. The sequence and structural differences between AQP3 and AQP10 provide insights into the differential compartmentalization and function of these two aquaporins commonly expressed in human intestines.
Fluoreto nas águas subterraneas dos aqüíferos Tubar?o e Cristalino, regi?o de Salto-Indaiatuba (SP)
Hypolito, Raphael;Ezaki, Sibele;Pérez-Aguilar, Annabel;
Rem: Revista Escola de Minas , 2010, DOI: 10.1590/S0370-44672010000400018
Abstract: anomalous concentrations of fluoride in groundwater were identified in 19 drilling wells in the salto-indaiatuba region, s?o paulo state, with an average concentration of 3.03 mg dm-3 and a maximum of 6.95 mg dm-3, which constitute a restriction for the water's usage in terms of human consumption. the wells exploit water from the tubar?o aquifer (sedimentary, granular) and crystalline aquifer (granitic, fractured), used for sanitary or industrial purposes. these groundwaters are typically hco3 and hco3-so4 types, with high concentrations of hco3-and na+ and high ph-values between 7.5 and 10.0. the highest concentrations of f- are associated to the tubar?o and tubar?o/crystalline aquifer drilling wells. the presence of f- in groundwater is controlled by these high ph-values, alkalinity, and fluorine availability. the source of fluoride in the tubar?o and crystalline aquifers can be related to the percolation of hydrothermal fluids associated with mesozoic lava flow, emplaced due to the opening of atlantic ocean and/or hydrolysis of fluorine-rich minerals and clay minerals.
Compartmentalization of Aquaporins in the Human Intestine
Hari H. P. Cohly,Raphael Isokpehi,Rajendram V. Rajnarayanan
International Journal of Environmental Research and Public Health , 2008,
Abstract: Improper localization of water channel proteins called aquaporins (AQP) induce mucosal injury which is implicated in Crohn ¢ € s disease and ulcerative colitis. The amino acid sequences of AQP3 and AQP10 are 79% similar and belong to the mammalian aquaglyceroporin subfamily. AQP10 is localized on the apical compartment of the intestinal epithelium called the glycocalyx while AQP3 is selectively targeted to the basolateral membrane. Despite the high sequence similarity and evolutionary relatedness, the molecular mechanism involved in the polarity, selective targeting and function of AQP3 and AQP10 in the intestine is largely unknown. Our hypothesis is that the differential polarity and selective targeting of AQP3 and AQP10 in the intestinal epithelial cells is influenced by amino acid signal motifs. We performed sequence and structural alignments to determine differences in signals for localization and posttranslational glycosylation. The basolateral sorting motif ¢ € YRLL ¢ € is present in AQP3 but absent in AQP10; while Nglycosylation signals are present in AQP10 but absent in AQP3. Furthermore, the C-terminal region of AQP3 is longer compared to AQP10. The sequence and structural differences between AQP3 and AQP10 provide insights into the differential compartmentalization and function of these two aquaporins commonly expressed in human intestines.
Recent Bioinformatics Advances in the Analysis of High Throughput Flow Cytometry Data
Raphael Gottardo,Ryan R. Brinkman,George Luta,Matt P. Wand
Advances in Bioinformatics , 2009, DOI: 10.1155/2009/461763
Abstract:
Dewetting of thin polymer films near the glass transition
F. Saulnier,E. Raphael,P. -G. de Gennes
Physics , 2002, DOI: 10.1103/PhysRevLett.88.196101
Abstract: Dewetting of ultra-thin polymer films near the glass transition exhibits unexpected front morphologies [G. Reiter, Phys. Rev. Lett., 87, 186101 (2001)]. We present here the first theoretical attempt to understand these features, focusing on the shear-thinning behaviour of these films. We analyse the profile of the dewetting film, and characterize the time evolution of the dry region radius, $R_{d}(t)$, and of the rim height, $h_{m}(t)$. After a transient time depending on the initial thickness, $h_{m}(t)$ grows like $\sqrt{t}$ while $R_{d}(t)$ increases like $\exp{(\sqrt{t})}$. Different regimes of growth are expected, depending on the initial film thickness and experimental time range.
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