bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tau isoforms which contain the domain encoded by exon 6 and their role in neurite elongation
Authors: Luo Min‐hua , Leski Michael L. , Andreadis Athena 
Published: March 2004

AbstractThe regulation of tau protein expression during different stages of cellular differentiation and development as well as its functional role in morphogenesis, neurofibrillary tangle formation, and neurodegeneration have been topics of extensive study but have not been completely clarified yet. Tau undergoes complex regulated splicing in the mammalian nervous system. Our previous study with tau exon 6 demonstrated that it shows a splicing regulation profile which is distinct from that of the other tau exons as well as a unique expression pattern which is spatially and temporally regulated. In this study, we investigated the expression, localization, and effects of tau isoforms which contain exon 6 in neuroblastoma cells which stably overexpress them. We found that expression of one particular combination of tau exons (the longest adult isoform plus the domain of exon 6) significantly inhibits neurite elongation. © 2004 Wiley‐Liss, Inc.
On graphs with strongly independent color‐classes
Authors: Gyárfás A. , Jensen T. , Stiebitz M. 
Published: March 2004

AbstractWe prove that for every k there is a k‐chromatic graph with a k‐coloring where the neighbors of each color‐class form an independent set. This answers a question raised by N. J. A. Harvey and U. S. R. Murty [4]. In fact we find the smallest graph Gk with the required property for every k. The graph Gk exhibits remarkable similarity to Kneser graphs. The proof that Gk is k‐chromatic relies on Lovász's theorem about the chromatic number of graphs with highly connected neighborhood complexes. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 1–14, 2004
A Steiner triple system which colors all cubic graphs
Authors: Grannell Mike , Griggs Terry , Knor Martin , Škoviera Martin 
Published: March 2004

AbstractWe prove that there is a Steiner triple system 𝒯 such that every simple cubic graph can have its edges colored by points of 𝒯 in such a way that for each vertex the colors of the three incident edges form a triple in 𝒯. This result complements the result of Holroyd and Škoviera that every bridgeless cubic graph admits a similar coloring by any Steiner triple system of order greater than 3. The Steiner triple system employed in our proof has order 381 and is probably not the smallest possible. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 15–24, 2004
Planar graph colorings without short monochromatic cycles
Authors: Kaiser Tomáš , Škrekovski Riste 
Published: March 2004

AbstractIt is well known that every planar graph G is 2‐colorable in such a way that no 3‐cycle of G is monochromatic. In this paper, we prove that G has a 2‐coloring such that no cycle of length 3 or 4 is monochromatic. The complete graph K5 does not admit such a coloring. On the other hand, we extend the result to K5‐minor‐free graphs. There are planar graphs with the property that each of their 2‐colorings has a monochromatic cycle of length 3, 4, or 5. In this sense, our result is best possible. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 25–38, 2004
Monotone drawings of planar graphs
Authors: Pach János , Tóth Géza 
Published: March 2004

AbstractLet G be a graph drawn in the plane so that its edges are represented by x‐monotone curves, any pair of which cross an even number of times. We show that G can be redrawn in such a way that the x‐coordinates of the vertices remain unchanged and the edges become non‐crossing straight‐line segments. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 39–47, 2004
On the number of quasi‐kernels in digraphs
Authors: Gutin Gregory , Koh Khee Meng , Tay Eng Guan , Yeo Anders 
Published: March 2004

AbstractA vertex set X of a digraph D = (V, A) is a kernel if X is independent (i.e., all pairs of distinct vertices of X are non‐adjacent) and for every v ∈ V‐X there exists x ∈ X such that vx ∈ A. A vertex set X of a digraph D = (V, A), is a quasi‐kernel if X is independent and for every v ∈ V‐X there exist w ∈ V‐X, x ∈ X such that either vx ∈ A or vw, wx ∈ A. In 1974, Chvátal and Lovász proved that every digraph has a quasi‐kernel. In 1996, Jacob and Meyniel proved that if a digraph D has no kernel, then D contains at least three quasi‐kernels. We characterize digraphs with exactly one and two quasi‐kernels, and, thus, provide necessary and sufficient conditions for a digraph to have at least three quasi‐kernels. In particular, we prove that every strong digraph of order at least three, which is not a 4‐cycle, has at least three quasi‐kernels. © 2004 Wiley Periodicals, Inc.
Density of the circular chromatic numbers of series‐parallel graphs
Authors: Pan Zhishi , Zhu Xuding 
Published: March 2004

AbstractSuppose G is a series‐parallel graph. It was proved in 3 that either χc(G) = 3 or χc(G) ≤ 8/3. So none of the rationals in the interval (8/3, 3) is the circular chromatic number of a series‐parallel graph. This paper proves that for every rational r ∈ [2, 8/3] ∪ {3} there exists a series‐parallel graph G with χc(G) = r. © 2004 Wiley Periodicals, Inc. J Graph Theory 46:57–68, 2004
The relaxed game chromatic number of outerplanar graphs
Authors: Dunn Charles , Kierstead Hal A. 
Published: March 2004

AbstractThe (r,d)‐relaxed coloring game is played by two players, Alice and Bob, on a graph G with a set of r colors. The players take turns coloring uncolored vertices with legal colors. A color α is legal for an uncolored vertex u if u is adjacent to at most d vertices that have already been colored with α, and every neighbor of u that has already been colored with α is adjacent to at most d – 1 vertices that have already been colored with α. Alice wins the game if eventually all the vertices are legally colored; otherwise, Bob wins the game when there comes a time when there is no legal move left. We show that if G is outerplanar then Alice can win the (2,8)‐relaxed coloring game on G. It is known that there exists an outerplanar graph G such that Bob can win the (2,4)‐relaxed coloring game on G. © 2004 Wiley Periodicals, Inc. J Graph Theory 46:69–78, 2004
The temporal and spatial patterns of thermal conditions in the area of the southwestern coast of the Gulf of Gdańsk (Poland) from 1951 to 1998
Authors: Miȩtus Mirosław , Filipiak Janusz 
Published: March 2004

AbstractThe variability of the thermal conditions in the environs of the southwestern coast of the Gulf of Gdańsk in the years 1951–98 has been analysed. The analyses were based on air temperature series from four stations characteristic of different locations. During the years analysed, the increase in minimum temperature was stronger than that of the maximum temperature; thus, a negative trend in the daily temperature range is observed. In the city, the statistically significant decrease in the daily temperature range is estimated as 0.015°C per annum. Mean values of both extreme temperatures indicate the thermally privileged areas, where stronger influences of local anthropogenic factors occur. The variability of heat and cold waves shows a positive trend in the number of heat waves and a negative trend for cold waves. The duration of heat waves is increasing. The duration of cold waves is characterized by a negative trend. Canonical correlation analysis was used to study the relationship between regional atmospheric circulation and local thermal conditions. The first two pairs of canonical maps explain 84% of the variance of the local daily temperature range and confirm the role of local factors in a differentiation of the thermal conditions. Copyright © 2004 Royal Meteorological Society
The upwelling regime off the West Portuguese Coast, 1941–2000
Authors: Lemos Ricardo T. , Pires Henrique O. 
Published: March 2004

AbstractThe evolution of the upwelling regime off west Portugal between 1941 and 2000 was investigated. Monthly averages of the longshore (meridional) wind component at four coastal stations of the Institute for Meteorology were computed and subject to linear regression analysis. Several comparisons were made among stations until a final regression model was reached. The resulting residuals were checked for the presence of red noise, and pairwise correlation coefficients were estimated for residuals of different stations. To complement this study, monthly sea‐surface temperature averages were computed for six regions off west Portugal and subject to a similar procedure. In both analyses, it was concluded that the Portuguese upwelling regime has weakened since the 1940s. The waning of the northerly, upwelling‐favourable winds was significant throughout the traditional upwelling season (April–September). Sea‐surface temperature showed a steady year‐round increase from 1941 onwards, in both offshore (+0.002°C/year) and coastal (+0.010°C/year) regions. Copyright © 2004 Royal Meteorological Society
Winter precipitation on the US Pacific coast and El Niño–southern oscillation events
Authors: Castello Amy F. , Shelton M. L. 
Published: March 2004

AbstractWinter precipitation increases as much as seven times from south to north along the US Pacific coast. For 1948–95, nine coastal grid points are used to identify spatial and temporal winter precipitation variations and to assess atmospheric circulation influences on precipitation variability. A strong negative correlation to the northwest of each precipitation grid point is revealed by one‐point correlation maps of precipitation at a given coastal grid point and 700 hPa geopotential heights at 288 grid points. The strength of the correlation decreases from north to south, and the northernmost precipitation grid point displays a correlation pattern nearly opposite that of the southernmost precipitation grid point. El Niño events are related to greater than average precipitation south of 43°N along the US Pacific coast. The largest negative height anomalies during an El Niño year are centred over the North Pacific Ocean west of Oregon. La Niña events display an asymmetric pattern relative to El Niño, with below‐normal rainfall along the California coast south of 41°N and above‐normal precipitation along coastal Oregon and Washington. La Niña years have negative 700 hPa geopotential height anomalies over the Gulf of Alaska. These characteristics delimit the region between 41 and 43°N as the transition zone defining El Niño–southern oscillation influences along the US Pacific coast. Copyright © 2004 Royal Meteorological Society
Rainfall and the length of the growing season in Nigeria
Authors: Odekunle T. O. 
Published: March 2004

AbstractThis study examines the length of the growing season in Nigeria using the daily rainfall data of Ikeja, Ondo, Ilorin, Kaduna and Kano. The data were collected from the archives of the Nigerian Meteorological Services, Oshodi, Lagos. The length of the growing season was determined using the cumulative percentage mean rainfall and daily rainfall probability methods.Although rainfall in Ikeja, Ondo, Ilorin, Kaduna, and Kano appears to commence around the end of the second dekad of March, middle of the third dekad of March, mid April, end of the first dekad of May, and early June respectively, its distribution characteristics at the respective stations remain inadequate for crop germination, establishment, and development till the end of the second dekad of May, early third dekad of May, mid third dekad of May, end of May, and end of the first dekad of July respectively. Also, rainfall at the various stations appears to retreat starting from the early third dekad of October, early third dekad of October, end of the first dekad of October, end of September, and early second dekad of September respectively, but its distribution characteristics only remain adequate for crop development at the respective stations till around the end of the second dekad of October, end of the second dekad of October, middle of the first dekad of October, early October, and middle of the first dekad of September respectively. Thus, the active lengths of the growing season are approximately 5 months, 5 months, 4 months, 4 months, and 2 months respectively. Plants that are short‐dry‐spell tolerant may thrive early in the rainy season, i.e. from the end of the second dekad of March to the end of the second dekad of May (in Ikeja), middle of the third dekad of March to the early third dekad of May (in Ondo), mid April to the middle of the third dekad of May (in Ilorin), end of the first dekad of May to end of May (in Kaduna), and early June to the end of the first dekad in July (in Kano), but other less tolerant plants should be planted starting from the end of the second dekad of May, early third dekad of May, mid third dekad of May, end of May, and end of the first dekad of July respectively. The daily rainfall probability method is recommended as more efficient in the assessment of the nature and length of the growing season. Copyright © 2004 Royal Meteorological Society
Decadal and longer term changes in El Niño–southern oscillation characteristics
Authors: Mokhov I. I. , Khvorostyanov D. V. , Eliseev A. V. 
Published: March 2004

AbstractThe time variations of El Niño–southern oscillation (ENSO) amplitude A, period P, and their relationship were studied using observed Niño‐3 sea‐surface temperature (SST) (GISST 2.2, GISST 2.3) and the southern oscillation index (SOI). Different tendencies in the A–P relationship were found in the decadal and longer term variations.On the decadal time scale, the SOI shows a statistically significant positive correlation between ENSO period and amplitude. This result was confirmed by analysing the observed Niño‐3 SST data as well.A negative relationship between longer variations in A and P was then found for certain subintervals of the observed SST time series available, e.g. for 1921–80 and 1903–94, and the dataset representing the latter period is the GISST 2.2 dataset. These longer variations can be interdecadal, and/or secular trends in the A (positive) and P (negative). In contrast, the SOI showed no trends in P and A; consequently, there were no significant P–A correlations found in the SOI data on these time scales.The ECHAM4/OPYC3 model was then tested in order to determine whether it could reproduce the tendencies found in the observed data. The ECHAM4/OPYC3 SST showed a negative A–P relationship in the simulation with increasing greenhouse‐gas concentration. This tendency did not manifest itself in the control run. The model SOI agrees with observation results, showing a positive correlation between ENSO period and amplitude on decadal time scales. Copyright © 2004 Royal Meteorological Society
Trends in extreme daily precipitation indices in India
Authors: Sen Roy Shouraseni , Balling Robert C. 
Published: March 2004

AbstractWe assembled daily precipitation records, initially for 3838 stations, throughout India and ultimately identified 129 stations with reasonably complete records over the period 1910 to 2000. From these daily records, we generated annual time series of seven different indices of extreme precipitation events, including total precipitation, largest 1, 5, and 30 day totals, and the number of daily events above the amount that marks the 90th, 95th, and 97.5th percentiles of all precipitation at each station. Of the 903 different time series (seven variables for 129 stations), 114 had a significant upward trend and 61 had a significant downward trend; overall, 61% of the time series showed an upward trend. The standard regression coefficients showing the strength and sign of the trend were highly correlated across the network. They generally showed increasing values in a contiguous region extending from the northwestern Himalayas in Kashmir through most of the Deccan Plateau in the south and decreasing values in the eastern part of the Gangetic Plain and parts of Uttaranchal. Our results are in general agreement with the prediction from numerical models for an increase in extreme precipitation events in India given the ongoing build‐up of greenhouse gases. Copyright © 2004 Royal Meteorological Society
On the use of relaxation parameters in hybrid smoothers
Authors: Yang Ulrike Meier 
Published: March 2004

AbstractThe use of relaxation parameters in hybrid smoothers within algebraic multigrid (AMG) is analysed both theoretically and practically. Relaxation parameters that are optimal under the assumptions of the theory are determined. The implementation of a procedure to automatically determine outer relaxation parameters for symmetric positive definite smoothers is described. Numerical results are presented, which show significant improvements over AMG with undamped hybrid smoothers. Copyright © 2004 John Wiley & Sons, Ltd.
Monotone multigrid methods based on element agglomeration coarsening away from the contact boundary for the Signorini's problem
Authors: Iontcheva Ana H. , Vassilevski Panayot S. 
Published: March 2004

AbstractTwo multilevel schemes for solving inequality constrained finite element second‐order elliptic problems, such as the Signorini's contact problem, are proposed and studied. The main ingredients of the schemes are that first they utilize element agglomeration coarsening away from the constraint set (boundary), which allows for easy construction of coarse level approximations that straightforwardly satisfy the fine‐grid constraints. Second important feature of the schemes is that they provide monotone reduction of the energy functional throughout the multilevel cycles. This is achieved by using monotone smoothers (such as the projected Gauss–Seidel method) and due to the fact that the recursive application of the two‐grid schemes is also monotone. The performance of the resulting methods is illustrated by numerical experiments on a model 2D Signorini's problem. Copyright 2004 © John Wiley & Sons, Ltd.
A multigrid approach to two‐dimensional phase unwrapping
Authors: Dardyk Gregory , Yavneh Irad 
Published: March 2004

AbstractThe two‐dimensional phase unwrapping problem is studied. Using the minimum Lp‐norm approach, we apply three different non‐linear multigrid algorithms for reconstructing surfaces from their ‘wrapped’ values—two classical approaches and a novel multilevel non‐linear method (MNM). The methods prove to be efficient even for difficult problems with noisy and discontinuous original images. The new method, MNM, exhibits the fastest and most robust convergence of the three, given an appropriate choice of a damping parameter. This parameter is determined automatically on very coarse grids at a small computational cost. Copyright 2004 John Wiley & Sons, Ltd.
Simulating sedimentation of liquid drops
Authors: Adekojo Waheed M. , Henschke Martin , Pfennig Andreas 
Published: March 2004

AbstractThis work was carried out to investigate the effect of fluid properties on the flow pattern and on the sedimentation velocity of an axisymmetric steady flow of a Newtonian fluid past a liquid drop in an unbounded region. The governing equations of motion were solved by the finite element method. The results show that the flow pattern of a liquid drop depends strongly both on the Reynolds number and on the ratio of the viscosity between the drop and the surrounding flowing fluids. The viscosity ratio in the range 0.02<μ*<50 has appreciable effect on the drag coefficient. Finally, a correlation for the sedimentation velocity is presented. Copyright © 2004 John Wiley & Sons, Ltd.
Consistent coupling of beam and shell models for thermo‐elastic analysis
Authors: Chavan K. S. , Wriggers P. 
Published: March 2004

AbstractIn this paper, the finite element formulation of a transition element for consistent coupling between shell and beam finite element models of thin‐walled beam‐like structures in thermo‐elastic problems is presented. Thin‐walled beam‐like structures modelled only with beam elements cannot be used to study local stress concentrations or to provide local mechanical or thermal boundary conditions. For this purpose, the structure has to be modelled using shell elements. However, computations using shell elements are a lot more expensive as compared to beam elements. The finite element model can be more efficient when the shell elements are used only in regions where the local effects are to be studied or local boundary conditions have to be provided. The remaining part of the structure can be modelled with beam elements. To couple these two models (i.e. shell and beam models) at transitional cross‐sections, transition elements are derived here for thermo‐elastic problems. The formulation encloses large displacement and rotational behaviour, which is important in case of thin‐walled beam‐like structures. Copyright © 2004 John Wiley & Sons, Ltd.
Mesh motion techniques for the ALE formulation in 3D large deformation problems
Authors: Farinatti Aymone José Luf́s 
Published: March 2004

AbstractEfficient mesh motion techniques are a key issue to achieve satisfactory results in the arbitrary Lagrangian–Eulerian (ALE) finite element formulation when simulating large deformation problems such as metal‐forming. In the updated Lagrangian (UL) formulation, mesh and material movement are attached and an excessive mesh distortion usually appears. By uncoupling mesh movement from material movement, the ALE formulation can relocate the mesh to avoid distortion. To facilitate the calculation process, the ALE operator is split into two steps at each analysis time step: UL step (where deformation due to loading is calculated without convective terms) and Eulerian step (where mesh motion is applied). In this work, mesh motion is performed by new nodal relocation methods, developed for eight‐node hexahedral elements, which can move internal and boundary nodes, improving and concentrating the mesh in critical zones. After mesh motion, data is transferred from the UL mesh to the relocated mesh using an expansion of stresses in a Taylor's series. Two numerical applications are presented, comparing results of UL and ALE formulation with results found in the literature. Copyright © 2004 John Wiley & Sons, Ltd.
Meshfree implementation for the real‐space electronic‐structure calculation of crystalline solids
Authors: Jun Sukky 
Published: March 2004

AbstractA meshfree formulation of the Schrödinger equation having periodic potential is presented. The conventional meshfree shape function is modified to express properly the periodicity of Bravais lattice. Then, it is applied to the electronic‐structure calculation of crystalline solids in real space. Numerical examples are the Kronig–Penney model potential and the empirical pseudopotentials of diamond and zinc‐blende semiconductors. Results prove that the meshfree method is a promising one to be used as a real‐space technique for the calculations of electronic structures. Copyright © 2004 John Wiley & Sons, Ltd.
Compliant rubber domains in a rigid polymer matrix: Shape and orientation factors related to cavitation and plastic dissipation
Authors: Fond C. , Schirrer R. 
Published: March 2004

AbstractThe hydrostatic stress in compliant rubber inclusions embedded in a rigid polymer matrix is evaluated for various shapes and orientations of the rubber domains and triaxialities of the remote stress tensor to determine the propensity of the inclusions to undergo cavitation. The first section analyzes the case of rubber particles of an ellipsoidal shape assuming linear elasticity of the matrix and small strains. It is shown that flat shapes, of which the long axis lies perpendicular to the direction of the maximum principal stress, are subjected to the highest levels of hydrostatic stress. The pressure induced by the deviatoric part of the remote stress tensor in the compliant rubber domains depends strongly on their shape and orientation, whereas the pressure induced by the hydrostatic part of the tensor is almost insensitive to the shape and orientation of the compliant domains. The second section examines the stress concentrations for elastoplasticity and plastic dissipation in the matrix. It is found that spherical inclusions ensure the best compromise between the early occurrence of plasticity and large amounts of plastic dissipation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1476–1486, 2004