bluuebunny/crossref_metadata_2025_split huggingface dataset:
Boundary Value Problems for Partial Differential Equations in the Plane Revisited
Authors: Mshimba Ali Seif 
Published: May 2007

AbstractBoth boundary value problems the DIRICHLET and the RIEMANN‐HILBERT problems, were solved by the author in the SOBOLEV space W1,p(D), 2 < p < ∞, for the elliptic differential equation in [8], [11] and [12]. In fact in most of the literature so far it is the case of p > 2 only which has been studied extensively. The results obtained so far relied on the fact that the VEKUA‐type operator TD maps the LEBESGUE space Lp(D) Into the HÖLDER space (D̄) for α= (p–2)/p. By modifying both VEKUA type singular integral operators TD and πD it is shown here that we can then solve both boundary value problems in W1,p(D) for 1 < p < ∞. While enlarging the set of admissible SOBOLEV spaces, the set of partial differential equations that can then be solved is reduced through stricter conditions on the LIPSCHITZ constants.
On the Fourier‐Coefficients of Vector‐Valued Functions
Authors: König Hermann 
Published: May 2007

AbstractWe study the decay of the Fourier‐coefficients of vector‐valued functions F : T → X, X a Banach space. Differentiable functions f generally have absolutely summable Fourier‐coefficients, f (n) <, iff X is K‐convex. More precise statements on the decay of f (n) for regular functions f can be given if X has Fourier‐type p. If f belongs to the Besov space, the sequence (||f(n)||) belongs to the Lorentz sequence space lt,v with 1/t = λ + 1/max (u′, p′). This result is the best possible in the vector‐valued case and generalizes the well‐known scalar results.
Γ‐Inequalities and Stability of Generalized Extremal Convolutions
Authors: Dolecki S. , Guillerme J. , Lignola M. B. , Malivert C. 
Published: May 2007

AbstractConvergence properties of convolutions, conjugations, compositions and polarities are expressed in terms of inequalities involving Γ‐operators and generalized extremal convolutions. It is shown that Γ‐inequalities amount to simple algebraic inequalities and (in some cases) to some min‐max problems. Numerous applications are indicated, in particular, to continuity properties of the classical conjugation.
Periodic Spline Interpolation on Uniform Meshes
Authors: Szyszka Uwe 
Published: May 2007

AbstractWe examine the interpolation with periodic polynomial splines of degree d and defect r (d ≦ r) on equidistant partitions of the real axis and generalize known results for r = 0. We prove necessary and sufficient conditions for the existence and a certain L2‐stability of the interpolants as well as their approximation properties in the scale of the periodic SOBOLEV spaces.
The Analytic Functionals in the Lower Half Plane as a Gel'fand‐Shilov Space
Authors: Duran Antonio J. 
Published: May 2007

AbstractIn this paper we introduce the space (related to the space of GUEL'FAND SHILOV) S+01 of f functions f in (0, + ∞) which satisfy sup tkf(n)(t)| < CAkBnkk for all n, k > 0 and certain C, A, B > O. We study the expansions of the elements of S+01 and those of its dual (S+01)′ with respect to the LAGUERRE orthonormal system, characterizing the sequences of FOURIER‐LAGUERRE coefficients which appear in these expansions. Also, we study the FOURIER transform, proving that it is an isomorphism from the space (S+01)′ onto the space of analytic functions in the lower half plane. We deduce that the space S+01 can be obtained by applying the FOURIER transform to the analytic functionals in the lower half plane. Some applications are given. Finally, we prove that if the spaces S+βα, are defined in (0, + ∞) in a similar way to the spaces of GEL'FAND‐SHILOV (for α, β 0), then, assumed Sβα = {0}, S+βα = {0} holds only for β = 0, α = 1.
The Spectrum of the Dirac Operator on the Hyperbolic Space
Authors: Bunke Ulrich 
Published: May 2007

AbstractWe represent the real hyperbolic space Hn as the rank one homogeneous space Spin (1, n)/Spin (n) and the spinor bundle S of H as the homogeneous bundle Spin (1, n) xSpin (n)VΔ where VΔ is the spinor representation space of Spin (n). The representation theoretic decomposition of L2(H, S) combined with the PARTHASARATHY formula for the DIRAC operator D yields the spectral representation of D2.
On a‐Posteriori Error Estimate of Approximate Solutions to a Mildly Nonlinear Nonpotential Elliptic Boundary Value Problem
Authors: Weisz Juraj 
Published: May 2007

AbstractThe paper deals with the construction of a computable a‐posteriori error estimate of the approximate solution to some nonpotential nonlinear elliptic boundary value problems. The convergence of the presented error estimate to the true error is proved. The method is illustrated on some numerical examples.
The KRÄTZEL Integral Transformation of Distributions
Authors: Barrios Javier A. , Betancor Jorge J. 
Published: May 2007

AbstractIn this paper we define an integral transformation, introduced by E. KRÄTZEL and denoted by Σ that is an extension of the LAPLACE transformation in certain spaces of generalized functions. We employ a procedure based on adjoint operators. We first show that the classical integral transformation is an isomorphism between two new FRÉCHET function spaces. Later the generalized Σ transformation is defined over the corresponding dual spaces as the adjoint of the classical transform. The MELLIN integral transformation is a very useful tool in our study.
The Sampling Theorem, DIRICHLET Series and BESSEL Functions
Authors: Klusch Dieter 
Published: May 2007

AbstractGeneralized forms of the classical WHITTAKER‐KOTELNIKOV‐SHANNON sampling theorem and of the extended BUTZER‐SPLETTSTÖSSER‐STENS sampling expansion for nonbandlimited signal functions are deduced from the famous functional equation of RIEMANN'S zeta‐function and from the well known NIELSEN‐DOETSCH summation formula for BESSEL functions. Hence a rather surprising connection between fundamental theorems of signal analysis and the theories of DIRICHLET and SCHLÖMILCH series is established.
Discontinuous Measure‐Valued Branching Processes and Generalized Stochastic Equations
Authors: Méléard Sylvie , Roelly Sylvie 
Published: May 2007

AbstractWe study a class of integrable and discontinuous measure‐valued branching processes. They are constructed as limits of renormalized spatial branching processes, the underlying branching distribution belonging to the domain of attraction of a stable law. These processes, computed on a test function f, are semimartingales whose martingale terms are identified with integrals of f with respect to a martingale measure. According to a representation theorem of continuous (respectively purely discontinuous) martingale measures as stochastic integrals with respect to a white noise (resp. to a POISSON process), we prove that the measure‐valued processes that we consider are solutions of stochastic differential equations in the space of L2 (Ω)‐valued vector measures.
A Combination Method for Local Bifurcation from Characteristic Values with Multiplicity
Authors: Tan Nguyen Xuan 
Published: May 2007

AbstractA combination of the LIAPUNOV‐SCHMIDT procedure, the implicit function theorems and the topological degree theory is used to investigate bifurcation points of equations of the form T(v) = L(λ, v) + M(λ, v), (λ, v) ϵ A × D̄, where A is an open subset in a normed space and for every fixed λ ϵ A, T, L(λ ·) and M(λ ·) are mappings from the closure D̄ of a neighborhood D of the origin in a BANACH space X into another BANACH space Y with T(0) = L(λ, 0) = M(λ, 0) = 0.Let Λ be a characteristic value of the pair (T, L) such that T − L( λ,·) is a FREDHOLM mapping with nullity p and index s, p > s ≧ 0. Under suitable hypotheses on T. L and M, (λ, 0) is a bifurcation point of the above equations. This generalizes the results of [4], [6], [8], [13] and [14] etc. An application of the obtained results to the axisymmetric buckling problem of a thin spherical shell will be given.
Calkin Representations of Unbounded Operator Algebras Acting on Non‐Separable Domains
Authors: Kürsten Klaus‐Detlef , Milde Michael 
Published: May 2007

AbstractThere are constructed representations of unbounded operator algebras which generalize representations of B(H) constructed by J. W. CALKIN and H. BEHNCKE. For a large class of unitary spaces D, each uniformly closed two‐sided ideal of the maximal Op*‐algebra L+ (D) appears as kernel of such a representation. Irreducibility of the representations is characterized in terms of properties of ultrafilters which define the representations.
Imaging mass spectrometry
Authors: McDonnell Liam A. , Heeren Ron M.A. 
Published: April 2007

AbstractImaging mass spectrometry combines the chemical specificity and parallel detection of mass spectrometry with microscopic imaging capabilities. The ability to simultaneously obtain images from all analytes detected, from atomic to macromolecular ions, allows the analyst to probe the chemical organization of a sample and to correlate this with physical features. The sensitivity of the ionization step, sample preparation, the spatial resolution, and the speed of the technique are all important parameters that affect the type of information obtained. Recently, significant progress has been made in each of these steps for both secondary ion mass spectrometry (SIMS) and matrix‐assisted laser desorption/ionization (MALDI) imaging of biological samples. Examples demonstrating localization of proteins in tumors, a reduction of lamellar phospholipids in the region binding two single celled organisms, and sub‐cellular distributions of several biomolecules have all contributed to an increasing upsurge in interest in imaging mass spectrometry. Here we review many of the instrumental developments and methodological approaches responsible for this increased interest, compare and contrast the information provided by SIMS and MALDI imaging, and discuss future possibilities. © 2007 Wiley Periodicals, Inc., Mass Spectrom. Rev.
Messunsicherheit in der Werkstoffprüfung
Authors: Polzin T. , Nowaczyk D. , Tscheuschner R. , Worch A. 
Published: April 2007

AbstractBei der Werkstoffprüfung muss bei jedem Messwert die jeweilige Messunsicherheit angegeben werden. Aus der 1995 erschienenen GUM [1] wurde 2000 der Uncert Report für verschiedenen Messverfahren entwickelt und als Code of Practice (COP) [2–4]. veröffentlicht. Diese sollen in Zusammenhang mit den in den Normen empfohlenen Verfahren und der praktischen Umsetzung dargestellt werden.
Multiple mechanisms of Erbb2 action after ultraviolet irradiation of the skin
Authors: Madson Justin G. , Hansen Laura A. 
Published: May 2007

AbstractUltraviolet (UV) irradiation causes multiple pathologic changes in the skin including inflammation, immune suppression, photoaging, and cancer. Effects of UV irradiation include the activation of numerous signal transduction pathways, including the mitogen‐activated protein kinases (MAPK), and the activation of transcription factors such as nuclear factor kappa B (NFκB). These responses alter gene expression in a manner that resembles the response to growth factors known as the “UV response”. The UV response alters the kinetics of cell division and cell death allowing the skin to recover from the DNA damage caused by UV exposure. UV irradiation also rapidly activates epidermal growth factor receptor (EGFR) family members, including Erbb2 (human epithelial growth factor receptor 2 (HER2)/neu), through the generation of reactive oxygen species. Erbb2, a protooncogene that is activated in many types of cancer and associated with aggressive and chemotherapeutic‐resistant disease, is expressed in both follicular and epidermal keratinocytes within the skin. However, the physiological functions of Erbb2 in the skin and its role in the UV response are largely unknown. In this review, evidence that Erbb2 is influential in modulating the response of the skin to UV will be presented. Erbb2 alters the expression of regulatory genes controlling inflammation, angiogenesis, cell division, apoptosis, cell adhesion, and migration following UV irradiation. In addition, Erbb2 dampens UV‐induced S‐phase arrest, augments inflammation in response to UV irradiation, and suppresses UV‐induced apoptosis. In summary, the evidence presented herein links UV‐induced Erbb2 activation to many of the effects of UV and implicates Erbb2 in UV‐induced carcinogenesis. © 2007 Wiley‐Liss, Inc.
Distinct roles of individual Smads in skin carcinogenesis
Authors: Bornstein Sophia , Hoot Kristina , Han Gang‐Wen , Lu Shi‐Long , Wang Xiao‐Jing 
Published: May 2007

AbstractTransforming growth factor β (TGFβ) signaling has both tumor suppression and promotion roles. Smads are transcription factors that primarily mediate intracellular signaling for the TGFβ superfamily. Loss of Smad2 and Smad4, but not Smad3 is common in human cancers. Given the complex nature of TGFβ signaling, dissection of the distinct role of each Smad in mediating the multiple functions of TGFβ signaling is warranted. To further analyze Smad deregulation during carcinogenesis, Smad2, Smad3, Smad4, and Smad7 were genetically modified in murine epidermis, and each alteration resulted in distinct skin phenotypes. Based on data from human cancer samples and from experimental models, Smad2 and Smad4 mainly function as tumor suppressors in skin carcinogenesis in vivo, whereas Smad3 and Smad7 may have dual roles in cancer. This review intends to summarize recent advances in the elucidation of the roles of Smad2, Smad3, Smad4, and Smad7 in skin carcinogenesis. © 2007 Wiley‐Liss, Inc.
Training program and learning curve in experimental microsurgery during the residency in plastic surgery
Authors: Lascar Ioan , Totir Dumitru , Cinca Adrian , Cortan Silviu , Stefanescu Andrei , Bratianu Raluca , Udrescu George , Calcaianu Nicolae , Zamfirescu Dragos G. 
Published: May 2007

AbstractThis article presents a comparison of microsurgical training of groups with different background. A protocol based on the rat femoral arterial anastomoses was used to provide an objective representation of the microsurgical skills progress. The performance is assessed by consistent (×4) patency of a standardized anastomosis. Three groups of beginner residents with progressive microsurgical experience and one group of experienced surgeons were observed. The patency curve of the beginner‐groups was as an abrupt learning curve, and then a plateau was reached. There was no statistically significant difference in the patency rate between the beginner‐groups after their first 32 anastomoses. No statistically significant difference was noted when the patency of the advanced group was compared with beginner‐groups after different numbers of anastomoses (inverse proportional with their training experience). A slight or a plateau learning curve was found among the experienced group. The learning curve is a useful adjunct in the assessment of training. © 2007 Wiley‐Liss, Inc. Microsurgery 2007.
Spleen autotransplantation. Morphological and functional follow‐up after spleen autotransplantation in mice: A research summary
Authors: Miko Iren , Brath Endre , Nemeth Norbert , Furka Andrea , Sipka Sandor , Peto Katalin , Serfozo Jozsef , Kovacs Judit , Imre Sandor , Benko Ilona , Galuska Laszlo , Sipka Sandor , Acs Geza , Furka Istvan 
Published: May 2007

AbstractIn 1986, we started the research on spleen surgery aimed at saving the splenic mass after its traumatic injury, with elaboration of special resection and autotransplantation techniques. The researches started on mongrel dogs and were continued on inbred mice and beagle dogs with complex histological, imaging, and laboratory investigations, following‐up the function and the regeneration of autotransplanted spleen chips. Performing research on mice provided more immunological methods, such as lymphocyte subsets, immunoglobulin levels, and monitoring the phagocytic functions. Researches showed evidence also on the presence of apoptosis, furthermore, stem cell studies on regeneration and functional restoration of the spleen chips are in progress. Our results contributed to two multidisciplinary guidelines in Hungary: (1) One of them is under preparation and underlines the importance of spleen saving methods after traumatic splenic injury; (2) The second guideline shows that hemorheological changes can be early indicators of the increased sensitivity to postsplenectomy infections. © 2007 Wiley‐Liss, Inc. Microsurgery 2007.
Improved cuff technique for cervical heart transplantation in mice
Authors: Gu Xiaodong , Xiang Jianbin , Zhou Yiming , Qian Shiguang , Chen Zongyou 
Published: May 2007

AbstractTo simplify the surgical procedure and increase the postoperative survival rate, an improved cuff technique was developed for cervical heart transplantation in mice. Forty cervical heart transplants have been performed in mice with a success rate of 92.5%. The total operative time was within 60 min, and the cold ischemic time for the graft hearts was minimized to less than 30 min. The improved cervical heart transplantation in mice by modified cuff technique is a practical and reliable animal model and can be done by surgeons with a little microsurgery experience. © 2007 Wiley‐Liss, Inc. Microsurgery 2007.
Cotransplanted hepatic stellate cells enhance vascularization of islet allografts
Authors: Yin Zhenyu , Wu Wenhan , Fung John J. , Lu Lina , Qian Shiguang 
Published: May 2007

AbstractIslet transplantation is an alternative to whole pancreas transplantation in curative therapy of diabetics. The outcome of engraftment of islet, however, remains disappointing. Rapid and adequate islet revascularization is crucial for the survival and function of transplanted islets. In this study, hepatic stellate cells (HSC) were cotransplanted with islet allografts, achieving marked prolongation of islet allografts. This was associated with enhanced revascularization within islet grafts as determined by anti‐CD31 antibody staining. © 2007 Wiley‐Liss, Inc. Microsurgery 2007.
Review of vascularized bone marrow transplantation: Current status and future clinical applications
Authors: Gordon Chad R. , Tai Chau Y. , Suzuki Hidetoshi , Strande Louise F. , Ramsamooj Rajendra , Matthews Martha S. , Black Kirby S. , Hewitt Charles W. 
Published: May 2007

AbstractIn this review, we examine the applicability of the vascularized bone marrow transplant (VBMT) as an alternative to conventional bone marrow transplantation (BMT). As a new surgical approach, the VBMT is unique by transplantation of the stromal environment that eliminates the need for an engraftment period, provides critical signaling and modulatory functions, and may potentiate tolerance induction. Thus far, VBMT studies have demonstrated an absence of graft‐versus‐host disease (GVHD) and robust engraftment into nonmanipulated as well as irradiated recipients with evidence of immunological tolerance. Further investigation is needed to determine the applicability of VBMT as an alternative to BMT. © 2007 Wiley‐Liss, Inc. Microsurgery 2007.
Elastic–ideally plastic beams and Prandtl–Ishlinskii hysteresis operators
Authors: Krejčí Pavel , Sprekels Jürgen 
Published: May 2007

AbstractThe one‐dimensional equation for transversal vibrations of an elastoplastic beam is derived from a general three‐dimensional system with a single‐yield tensorial von Mises plasticity model. It leads after dimensional reduction to a multiyield scalar Prandtl–Ishlinskii hysteresis model whose weight function is explicitly given. The use of Prandtl–Ishlinskii operators in elastoplasticity is thus not just a questionable phenomenological approach, but in fact quite natural. The resulting partial differential equation with hysteresis is transformed into an equivalent system for which the existence and uniqueness of a strong solution is proved. The proof employs techniques from the mathematical theory of hysteresis operators. Copyright © 2007 John Wiley & Sons, Ltd.
Linear time algorithms for approximating the facility terminal cover problem
Authors: Xu Guang , Yang Yang , Xu Jinhui 
Published: May 2007

AbstractIn this paper, we consider an interesting generalization of the weighted vertex cover problem, called the Facility Terminal Cover (FTC) problem. In the FTC problem, each vertex is associated with a positive weight, each edge is associated with a positive demand, and the objective is to determine a subset of vertices and a capacity for each selected vertex so that the demand of each edge is covered by the capacity of one of its two endpoints and the total weighted capacity of all selected vertices is minimized. The FTC problem is motivated by several key network optimization problems, such as the power assignment problem in ad hoc networks, and could be used as a subroutine to solve such problems. No quality‐guaranteed solution is previously known for the FTC problem. In this paper, we present two linear time approximation algorithms for this problem. Our first algorithm achieves deterministically an approximation ratio of 8 by using an interesting rounding technique and a lower‐bounding technique. Based on interesting randomization techniques, our second algorithm further improves the approximation ratio to 2e, whereeis the natural logarithmic base. The second algorithm can be easily derandomized in quadratic time. Our algorithms are relatively simple and can be easily implemented for networking applications. Experiments show that the two algorithms behave rather similarly, especially in large‐size graphs, indicating that the solutions yielded by one or both algorithms are much closer to the optimum. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(1), 118–126 2007
Toward realization of computational homogenization in practice
Authors: Yuan Zheng , Fish Jacob 
Published: May 2007

AbstractWe present a computational homogenization approach for linear and non‐linear solid mechanics problems, which is fully compatible with conventional finite element code architecture. A seamless implementation in ABAQUS is presented including Python script, validation problems and a web‐link where script files, user‐defined subroutines and input files can be accessed. For linear problems, we demonstrate how to utilize ABAQUS existing facilities to develop analysis attributes required for solving a unit‐cell problem. For non‐linear problems, a Python script invoked by a coarse‐scale stress update procedure is introduced to carry out the scale bridging. The purpose of this paper is twofold: (i) to motivate practitioners to adopt the computational homogenization as an integral part of their analysis and design process; and (ii) to encourage commercial code vendors to seamlessly integrate the architectures proposed in their legacy codes. Copyright © 2007 John Wiley & Sons, Ltd.
A heterogeneous space–time full approximation storage multilevel method for molecular dynamics simulations
Authors: Waisman Haim , Fish Jacob 
Published: May 2007

AbstractA heterogeneous space–time full approximation storage (HFAS) multilevel formulation for molecular dynamics simulations is developed. The method consists of a waveform Newton smoothing that produces initial space–time iterates and a coarse model correction. The formulation is coined as heterogeneous since it permits different interatomic potentials to be applied at different physical scales. This results in a flexible framework for physics coupling. Time integration is performed in windows using the implicit Newmark predictor–corrector method that permits larger time integration steps than the explicit method. The size of the time steps is governed by accuracy rather than by stability considerations of the algorithm. We study three different variants of the method: the Picard iteration, constrained dynamics and force splitting. Numerical examples show that FAS based on force splitting provides significant time savings compared to standard explicit methods and alternative implicit space–time schemes. Parallel studies of the Picard iteration on harmonic problems illustrate the time parallelization effect that leads to a superior parallel performance compared to explicit methods. Copyright © 2007 John Wiley & Sons, Ltd.