bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the finite‐time singularities of the 3D incompressible Euler equations
Authors: Chae Dongho 
Published: May 2006

AbstractWe prove the finite‐time vorticity blowup, in the pointwise sense, for solutions of the 3D incompressible Euler equations assuming some conditions on the initial data and its corresponding solutions near initial time. These conditions are represented by the relation between the deformation tensor and the Hessian of pressure, both coupled with the vorticity directions associated with the initial data and solutions near initial time. We also study the possibility of the enstrophy blowup for the 3D Euler and the 3D Navier‐Stokes equations, and prove the finite‐time enstrophy blowup for initial data satisfying suitable conditions. Finally, we obtain a new blowup criterion that controls the blowup by a quantity containing the Hessian of the pressure. © 2006 Wiley Periodicals, Inc.
On the number of interior peak solutions for a singularly perturbed Neumann problem
Authors: Lin Fang‐Hua , Ni Wei‐Ming , Wei Jun‐Cheng 
Published: May 2006

AbstractWe consider the following singularly perturbed Neumann problem:

where Δ = Σ ∂2/∂x is the Laplace operator, ϵ > 0 is a constant, Ω is a bounded, smooth domain in ℝN with its unit outward normal ν, and f is superlinear and subcritical. A typical f is f(u) = up where 1 < p < +∞ when N = 2 and 1 < p < (N + 2)/(N − 2) when N ≥ 3.We show that there exists an ϵ0 > 0 such that for 0 < ϵ < ϵ0 and for each integer K bounded by

where αN, Ω, f is a constant depending on N, Ω, and f only, there exists a solution with K interior peaks. (An explicit formula for αN, Ω, f is also given.) As a consequence, we obtain that for ϵ sufficiently small, there exists at least [αN, Ωf/ϵN (|ln ϵ|)N] number of solutions. Moreover, for each m ∈ (0, N) there exist solutions with energies in the order of ϵN−m. © 2006 Wiley Periodicals, Inc.
Tg(Afp‐GFP) expression marks primitive and definitive endoderm lineages during mouse development
Authors: Kwon Gloria S. , Fraser Stuart T. , Eakin Guy S. , Mangano Michael , Isern Joan , Sahr Kenneth E. , Hadjantonakis Anna‐Katerina , Baron Margaret H. 
Published: May 2006

AbstractAlpha‐fetoprotein (Afp) is the most abundant serum protein in the developing embryo. It is secreted by the visceral endoderm, its derivative yolk sac endoderm, fetal liver hepatocytes, and the developing gut epithelium. The abundance of this protein suggested that Afp gene regulatory elements might serve to effectively drive reporter gene expression in developing endodermal tissues. To this end, we generated transgenic mouse lines Tg(Afp‐GFP) using an Afp promoter/enhancer to drive expression of green fluorescent protein (GFP). Bright GFP fluorescence allowed the visualization, in real time, of visceral endoderm, yolk sac endoderm, fetal liver hepatocytes, and the epithelium of the gut and pancreas. Comparison of the localization of green fluorescence with that of endogenous Afp transcripts and protein indicated that the regulatory elements used to generate these mouse lines directed transgene expression in what appeared to be all Afp‐expressing cells of the embryo, but only in a subset of fetal liver cells. The bright GFP signal permitted flow cytometric analysis of fetal liver hepatocytes. These mice represent a valuable resource for live imaging as well as identification, quantitation, and isolation of cells from the primitive and definitive endoderm lineages of the developing mouse embryo. Developmental Dynamics 235:2549–2558, 2006. © 2006 Wiley‐Liss, Inc.
Nas transgenic mouse line allows visualization of Notch pathway activity in vivo
Authors: Souilhol Céline , Cormier Sarah , Monet Marie , Vandormael‐Pournin Sandrine , Joutel Anne , Babinet Charles , Cohen‐Tannoudji Michel 
Published: May 2006

AbstractThe Notch signaling pathway plays multiple and important roles in mammals. However, several aspects of its action, in particular, the precise mapping of its sites of activity, remain unclear. To address this issue, we generated a transgenic line carrying a construct consisting of a nls‐lacZ reporter gene under the control of a minimal promoter and multiple RBP‐Jκ binding sites. Here we show that this transgenic line, which we termed NAS (for Notch Activity Sensor), displays an expression profile that is consistent with current knowledge on Notch activity sites in mice, even though it may not report on all these sites. Moreover, we observe that NAS transgene expression is abolished in a RBP‐Jκ‐deficient background, indicating that it indeed requires Notch/RBP‐Jκ signaling pathway activity. Thus, the NAS transgenic line constitutes a valuable and versatile tool to gain further insights into the complex and various functions of the Notch signaling pathway. genesis 44: 277–286, 2006. © 2006 Wiley‐Liss, Inc.
Titanium–Alkaline Earth Molecular Oxides as Supports for Carbanions Derived from μ3‐Ethylidyne Groups (Eur. J. Inorg. Chem. 11/2006)
Authors: Martín Avelino , Mena Miguel , Morales‐Varela María del Carmen , Santamaría Cristina 
Published: May 2006

AbstractThe cover picture shows how the treatment of the oxide molecular model [{TiCp*(μ‐O)}3(μ3‐CMe)] (Cp* = η5‐C5Me5) with alkaline earth metal amide and alkyl compounds produces the deprotonation of the μ3‐ethylidyne fragment to give μ3‐CCH2−, μ3‐CHCH− or μ3‐CCH2− carbanions. Simultaneously, the alkaline earth cation is incorporated through the oxygen atoms to build new cage structures. Details of this chemistry are described by M. Mena et al. on p. 2137 ff.
Regio‐ and Stereoselective Synthesis of anti‐1,3‐Diaryl‐3‐chloro‐ 2‐(o‐nitrophenylsulfonylamino)‐3‐propan‐1‐ones through Catalytic Aminohalogenation Reaction of α,β‐Unsaturated Ketones
Authors: Liu Junying , Wang Yining , Li Guigen 
Published: May 2006

AbstractThe synthesis of anti‐1,3‐diaryl‐3‐chloro‐2‐(2‐nitrophenylsulfonylamino)‐3‐propan‐1‐ones has been achieved. The aminohalogenation of α,β‐unsaturated ketones resulted in the vicinal haloamine products in high regio‐ and stereoselectivity and modest to good chemical yields. The reaction can be conducted under convenient conditions by using the combination of 2‐NsNCl2/2‐NsNHNa (2‐Ns = 2‐nosyl = 2‐nitrophenylsulfonyl) as the nitrogen/chlorine source and by using copper(I) triflate as the catalyst. An N‐(2‐nosyl)‐N‐H‐aziridinium intermediate was proposed to exist in the aminohalogenation process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
The Synthesis of 4‐Hydroxypipecolic Acids by Stereoselective Cycloaddition of Configurationally Stable Nitrones
Authors: Cordero Franca M. , Bonollo Simona , Machetti Fabrizio , Brandi Alberto 
Published: May 2006

AbstractThe diastereoselective synthesis of trans‐ and cis‐4‐hydroxypipecolic acids has been achieved with geometry‐controlled nitrone cycloaddition chemistry. The cycloaddition of 3‐butenol to enantiopure C‐aminocarbonyl and C‐alkoxycarbonyl nitrones having a definite (Z) and (E) configuration, respectively, occurs with complete regio‐ and exo selectivity. The acyclic (Z)‐nitrone 12 affords two cycloadducts in a 1:1 ratio, which can be separated and converted into (2R,4R)‐ and (2S,4S)‐4‐hydroxypipecolic acids, respectively, in four steps. The cyclic (E)‐nitrone 17 reacts with complete diastereofacial selectivity and the elaboration of its sole adduct gives the methyl ester of (2R,4S)‐4‐hydroxypipecolic acid, albeit in low yield. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Bayesian semiparametric model for organism based environmental reconstruction
Authors: Bhattacharya Sourabh 
Published: May 2006

AbstractReconstruction of past environment based on fossil data is an important scientific problem and much work has been done to address this. One important issue in this regard is the relationship between species and environment. The available statistical approaches, both classical and Bayesian, make the assumption that species abundances occur symmetrically around a single preferable environmental condition. In other words, it is generally assumed that the relationship between species and environment is unimodal. However, this may not be true in reality.In this paper, we propose a Bayesian hierarchical model, extending previous work, to incorporate multiple preferences (or, multiple modes) of each species. In particular, we propose to use a mixture of Gaussian response curves to relate species to environment. A main novelty of our approach is the use of Dirichlet process to learn about the number of preferences of each species. We demonstrate that our multimodal modeling approach performs better than unimodal model. For implementation of our approach, we use a recently developed efficient computational procedure. Copyright © 2006 John Wiley & Sons, Ltd.
Trees as riparian engineers: the Tagliamento river, Italy
Authors: Gurnell Angela , Petts Geoffrey 
Published: May 2006

AbstractPristine river corridors were characterized by island and floodplain development driven by the inter‐play of flows, sediments and woody vegetation. Here we explore these relationships within topographically controlled settings within the upper, middle and lower reaches of a large, semi‐natural alpine to mediterranean river. These reaches have expanding or contracting valley floors within which we show that there are more or less predictable patterns of stream power and rates of vegetation growth, reflecting water availability during dry periods and also the availability of sand and finer sediment. We relate these to the pattern of island distribution that is repeated within the three reaches and is indicative of the engineering role of riparian trees. Islands are shown to develop within thresholds defined by stream power, rates of woody vegetation growth and rates of sedimentation, and to develop most quickly where riparian species include those capable of sprouting from driftwood. Copyright © 2006 John Wiley & Sons, Ltd.
Multi‐year tracking of sediment sources in a small agricultural watershed using rare earth elements
Authors: Kimoto A. , Nearing M. A. , Shipitalo M. J. , Polyakov V. O. 
Published: May 2006

AbstractRare earth elements (REEs) have been successfully used as a sediment tracer, but the REE technique has never been used for studying sediment sources for a multi‐year period. A nearly four‐year field experiment was conducted on a small agricultural watershed near Coshocton, OH, USA, to assess the applicability of the REE technique for a multi‐year period and to evaluate the relative contributions of sediment sources in the watershed. Tracer depletion and tracer enrichment ratio (ratio of the tracer concentrations in sediment to the concentrations in the soil in the areas of application) were evaluated to examine the applicability and accuracy of the technique. A minimum of 91 per cent of the mass of the applied elements was still available on any individual morphological element at the end of the experimental period. The tracer enrichment ratio varied from 0·4 to 2·3, and it was not significantly related to time. The relative contributions of six morphological elements within the watershed were evaluated as proportions to total sediment yield. The relative contribution of the lower channel was significantly increased as a function of the amount of sediment yield, while that of the lower backslope was significantly decreased. The relative contribution of the lower channel significantly decreased as a function of cumulative sediment yield, while the contributions of the shoulder and the upper backslope significantly increased. Our results showed that the REE technique can be used to track sediment sources for a relatively long period with two limitations or potential sources of error associated with a selective depletion of tracers and a contamination of downslope areas with tagged sediments from upslope areas. Copyright © 2006 John Wiley & Sons, Ltd.
Lithological control on the elevation of shore platforms in a microtidal setting
Authors: Kennedy D. M. , Dickson M. E. 
Published: May 2006

AbstractThe shore platforms on Shag Point, southern New Zealand, are quasi‐horizontal surfaces and are developed between supratidal and low water spring levels. A range of morphologies occur, with more exposed platforms having a distinct low‐tide cliff, in contrast to low‐tide surfaces where the seaward edge is buried beneath rubble and macro‐algal growth. The platforms range in width from 20 to 80 m and are eroded into Late Cretaceous/Early Tertiary fine marine sandstones and mudstones. Shore platforms have formed in two principal lithological units: a homogeneous unit that is characterized by few discontinuities, and a fractured unit with joints spaced about 0·5 m apart. Rock hardness is low in both units (L‐type Schmidt hammer rebound values of 31 ± 4), and there is little systematic variation in values between the two units in which platforms have developed. Case‐hardened concretions within the sandstone are significantly harder than surrounding rock and cause local relief of metre scale as the spherical diagenetic features are eroded from the bedrock. They do not, however, appear to affect broad‐scale platform geometry. Joints within the bedrock are a primary control on platform elevation. Platforms formed in jointed rock occur at the lower portion of the intertidal zone, in contrast to platforms formed in unjointed bedrock, in which horizontal surfaces occur at or above mean high water spring tide level. Rock structure, therefore, appears to be the primary determinant factor of platform geometry at Shag Point. Copyright © 2006 John Wiley & Sons, Ltd.
Bank stability analysis for regime models of vegetated gravel bed rivers
Authors: Eaton Brett C. 
Published: May 2006

AbstractA new bank stability analysis procedure is developed for use in rational regime models predicting reach average channel dimensions. The performance of a regime model using this new bank stability formulation is compared against that for a model using the modified friction angle approach proposed by Millar and Quick (1993). The bank stability assessment is based on a conceptual model that more closely represents conditions found in gravel bed rivers with vegetated floodplains: the primary effect of vegetation is its contribution to a stable upper bank, the position of which is determined by erosion of unvegetated bed material at the toe of the bank. The vertical height of the upper bank is estimated using a simple slab failure model and assigning an effective cohesion to the vegetation‐reinforced soil. The geometry of the lower slope and the width of the channel are determined iteratively using the regime approach described by Eaton et al. (2004). A comparison of the predicted stream channel widths for stable gravel bed channels classified according to riparian vegetation type (Hey and Thorne, 1986) showed that this new formulation increases model accuracy, especially for the more densely vegetated channel types. Since the strength parameters used in the model can be estimated from the observed bank geometry, the potential for applying and testing rational regime models in the field has been significantly improved. Copyright © 2006 John Wiley & Sons, Ltd.
Divergent response of an intertidal swash bar
Authors: Houser Chris , Greenwood Brian , Aagaard Troels 
Published: May 2006

AbstractThis paper examines the processes responsible for the morphodynamics of an intertidal swash bar at Skallingen, Denmark, during seven successive storms (one with a large surge of +3·02 m DNN). During this period a subtidal bar migrated landward onto the foreshore and continued to migrate across the intertidal zone as a swash bar. The onshore migration of the inner subtidal bar resulted from the erosion of sediment from the upper foreshore and dune ramp during the large storm surge that was transported seaward, causing the landward displacement of the bar through accretion on the landward slope. The magnitude and direction of suspended sediment transport within the intertidal zone, and more specifically at and close to the crest of the swash bar, varied with the ratio of both the significant (Hs) and average (Havg) wave heights to the water depth (hcr) at the swash bar crest (the local depth minimum). The transition between onshore and offshore suspended sediment transport was associated with the average wave of the incident distribution breaking on the swash bar crest (Havgh ≈ 0·33). While the onshore‐directed transport was largest at infragravity frequencies, sediment resuspension was best explained by the skewed accelerations under the surf bores. Offshore transport was dominated by the cross‐shore mean currents (undertow) that developed when the significant wave of the distribution broke on the swash bar crest (Hsh ≈ 0·33) and weakened as the average wave of the distribution started to break at the crest (Havgh ≈ 0·33) and the surf zone approached saturation. In contrast to subtidal bars, the swash bar at Skallingen exhibited a divergent behaviour with respect to the cross‐shore position of the breaker zone, migrating onshore when the average wave broke seaward of the crest and migrating offshore when the average wave broke landward of the crest. Copyright © 2006 John Wiley & Sons, Ltd.
Investigation of coupling between surface processes and induced flow in the lower continental crust as a cause of intraplate seismicity
Authors: Westaway Rob 
Published: May 2006

AbstractMany studies have highlighted the role of coupling between surface processes and flow in the lower continental crust in deforming the crust and creating topographic relief over Quaternary timescales. On the basis of the rheological knowledge gained, it is suggested that intraplate seismicity can also be caused by coupling between surface processes and flow in the lower continental crust. This view is shown to be a natural consequence of the modern idea that isostatic equilibrium is maintained by flow in the weak lower crust in response to erosion and sedimentation. It is supported by a general correlation between the vigour of surface processes and rates of intraplate seismicity, and by instances of seasonal seismicity that correlates with seasonal climate. Human interference in the environment can affect surface loading: for instance, deforestation for agriculture or urban development can cause increased erosion rates; global warming is expected to cause increased storminess (and thus increased erosion rates) and/or global sea‐level rise. The possibility of increased rates of seismicity resulting from these processes should thus be considered in future hazard assessment. Copyright © 2006 John Wiley & Sons, Ltd.
Modelling the potential impacts of groundwater hydrology on long‐term drainage basin evolution
Authors: Huang Xiangjiang , Niemann Jeffrey D. 
Published: May 2006

AbstractFluvial erosion processes are driven by water discharge on the land surface, which is produced by surface runoff and groundwater discharge. Although groundwater is often neglected in long‐term landscape evolution problems, water table levels control patterns of Dunne runoff production, and groundwater discharge can contribute significantly to storm flows. In this analysis, we investigate the role that groundwater movement plays in long‐term drainage basin evolution by modifying a widely used landscape evolution model to include a more detailed representation of basin hydrology. Precipitation is generated by a stochastic process, and the precipitation is partitioned between surface runoff and groundwater recharge using a specified infiltration capacity. Groundwater flow is simulated by a dynamic two‐dimensional Dupuit equation for an unconfined aquifer with an irregular underlying impervious layer. The model is applied to the WE‐38 basin, an experimental catchment in Pennsylvania, because 60–80 per cent of the discharge is derived from groundwater and substantial hydrologic and geomorphic information is available. The hydrologic model is first calibrated to match the observed streamflows, and then the combined hydrologic/geomorphic model is used to simulate scenarios with different infiltration capacities. The results of this modelling exercise indicate that the basin can be divided into three zones with distinct streamflow‐generating characteristics, and different parts of the basin can have different geomorphic effective events. Over long periods of time, scenarios in which groundwater discharge is large tend to modify the topography in a way that promotes groundwater discharge and inhibits Dunne runoff. Copyright © 2006 John Wiley & Sons, Ltd.
Aeolian sediment transport on a human‐altered foredune
Authors: Nordstrom Karl F. , Jackson Nancy L. , Hartman Jean Marie , Wong Mark 
Published: May 2006

AbstractChanges in wind speed and sediment transport are evaluated at a gap and adjacent crest of a 2 to 3 m high, 40 m wide foredune built by sand fences and vegetation plantings on a wide, nourished fine sand beach at Ocean City, New Jersey. Anemometer masts, cylindrical sand traps and erosion pins were placed on the beach and dune during two obliquely onshore wind events in February and March 2003. Results reveal that: (1) changes in the alongshore continuity of the beach and dune system can act as boundaries to aeolian transport when winds blow at an angle to the shoreline; (2) oblique winds blowing across poorly vegetated patches in the dune increase the potential for creating an irregular crest elevation; (3) transport rates and deflation rates can be greater within the foredune than on the beach, if the dune surface is poorly vegetated and the beach has not had time to dry following tidal inundation; (4) frozen ground does not prevent surface deflation; and (5) remnant sand fences and fresh storm wrack have great local but temporary effect on transport rates. Temporal and spatial differences due to sand fences and wrack, changes in sediment availability due to time‐dependent differences in surface moisture and frozen ground, combined with complex topography and patchy vegetation make it difficult to specify cause–effect relationships. Effects of individual roughness elements on the beach and dune on wind flow and sediment transport can be quantified at specific locations at the event scale, but extrapolation of each event to longer temporal and spatial scales remains qualitative. Copyright © 2006 John Wiley & Sons, Ltd.