bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling of failure mode transition in ballistic penetration with a continuum model describing microcracking and flow of pulverized media
Authors: Gailly Benjamin A. , Espinosa Horacio D. 
Published: October 2002

AbstractAn Erratum has been published for this article in International Journal for Numerical Methods in Engineering 2002; 55(4):499–501. A new continuum model to describe damage, fragmentation and large deformation of pulverized brittle materials is presented. The multiple‐plane‐microcracking (MPM) model, developed by Espinosa, has been modified to track microcracking on 13 orientations under high pressure, high strain rate and high deformation. This model provides the elastic and inelastic response of the material before massive crack coalescence. When pulverization occurs, the constitutive response is modelled by means of a visco‐plastic model for granular material, which is a generalization to three dimensions of the double‐sliding theory augmented by a consolidation mechanism. The initialization of the granular model is governed by a yield surface at the onset of massive crack coalescence. This is accomplished by examining a representative volume element, modelled using the MPM model, in compression‐shear. The main advantage of this approach is to keep a continuum model at all stages of the deformation process and thus avoid the difficulties of crack representation in a discrete finite element code. This model has been implemented in LS‐DYNA and used to examine interface defeat of long rod penetrators by a confined ceramic plate. The numerical simulations are compared to experiments in order to identify failure modes. The model parameters were obtained independently by simulating plate and rod impact experiments. The proposed model captures most of the physical observations as well as failure mode transition, from interface defeat to full penetration, with increasing impact velocity. Copyright © 2002 John Wiley & Sons, Ltd.
A vector level set method and new discontinuity approximations for crack growth by EFG
Authors: Ventura G. , Xu J. X. , Belytschko T. 
Published: October 2002

AbstractA new vector level set method for modelling propagating cracks in the element‐free Galerkin (EFG) method is presented. With this approach only nodal data are used to describe the crack; no geometrical entity is introduced for the crack trajectory, and no partial differential equations need to be solved to update the level sets. The nodal description is updated as the crack propagates by geometric equations. The advantages of this approach, here introduced and analysed for the two‐dimensional case, are particularly promising in three‐dimensional applications, where the geometrical description and evolution of an arbitrary crack surface in a complex solid is very awkward. In addition, new methods for crack approximations in EFG are introduced, using a jump function accounting for the displacement discontinuity along the crack faces and the Westergard's solution enrichment near the crack tip. These enrichments, being extrinsic, can be limited only to the nodes surrounding the crack and are naturally coupled to the level set crack representation. Copyright © 2002 John Wiley & Sons, Ltd.
Accurate reanalysis of structures by a preconditioned conjugate gradient method
Authors: Kirsch Uri , Kocvara Michal , Zowe Jochem 
Published: October 2002

AbstractA preconditioned conjugate gradient (PCG) method that is most suitable for reanalysis of structures is developed. The method presented provides accurate results efficiently. It is easy to implement and can be used in a wide range of applications, including non‐linear analysis and eigenvalue problems. It is shown that the PCG method presented and the combined approximations (CA) method developed recently provide theoretically identical results. Consequently, available results from one method can be applied to the other method. Effective solution procedures developed for the CA method can be used for the PCG method, and various criteria and error bounds developed for conjugate gradient methods can be used for the CA method. Numerical examples show that the condition number of the selected preconditioned matrix is much smaller than the condition number of the original matrix. This property explains the fast convergence and accurate results achieved by the method. Copyright © 2002 John Wiley & Sons, Ltd.
A feature‐preserving volumetric technique to merge surface triangulations
Authors: Cebral Juan R. , Camelli Fernando E. , Löhner Rainald 
Published: October 2002

AbstractSeveral extensions and improvements to surface merging procedures based on the extraction of iso‐surfaces from a distance map defined on an adaptive background grid are presented. The main objective is to extend the application of these algorithms to surfaces with sharp edges and corners. In order to deal with objects of different length scales, the initial background grids are created using a Delaunay triangulation method and local voxelizations. A point enrichment technique that introduces points into the background grid along detected surface features such as ridges is used to ensure that these features are preserved in the final merged surface. The surface merging methodology is extended to include other Boolean operations between surface triangulations. The iso‐surface extraction algorithms are modified to obtain the correct iso‐surface for multi‐component objects. The procedures are demonstrated with various examples, ranging from simple geometrical entities to complex engineering applications. The present algorithms allow realistic modelling of a large number of complex engineering geometries using overlapping components defined discretely, i.e. via surface triangulations. This capability is very useful for grid generation starting from data originated in measurements or images. Copyright © 2002 John Wiley & Sons, Ltd.
Multi‐scale constitutive modelling of heterogeneous materials with a gradient‐enhanced computational homogenization scheme
Authors: Kouznetsova V. , Geers M. G. D. , Brekelmans W. A. M. 
Published: October 2002

AbstractA gradient‐enhanced computational homogenization procedure, that allows for the modelling of microstructural size effects, is proposed within a general non‐linear framework. In this approach the macroscopic deformation gradient tensor and its gradient are imposed on a microstructural representative volume element (RVE). This enables us to incorporate the microstructural size and to account for non‐uniform macroscopic deformation fields within the microstructural cell. Every microstructural constituent is modelled as a classical continuum and the RVE problem is formulated in terms of standard equilibrium and boundary conditions. From the solution of the microstructural boundary value problem, the macroscopic stress tensor and the higher‐order stress tensor are derived based on an extension of the Hill–Mandel condition. This automatically delivers the microstructurally based constitutive response of the higher‐order macro continuum and deals with the microstructural size in a natural way. Several examples illustrate the approach, particularly the microstructural size effects. Copyright © 2002 John Wiley & Sons, Ltd.
A multisymplectic variational integrator for the nonlinear Schrödinger equation
Authors: Chen Jing‐Bo , Qin Meng‐Zhao 
Published: October 2002

AbstractThe multisymplectic structure for the nonlinear Schrödinger equation is presented. Based on the multisymplectic structure, we derive a nine‐point variational integrator from the discrete variational principle and a six‐point multisymplectic integrator from the Preissman multisymplectic scheme. We show that the two integrators are essentially equivalent. Therefore, we call it a multisymplectic variational integrator. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 523–536, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/num.10021
EGFR family expression in breast carcinomas. c‐erbB‐2 and c‐erbB‐4 receptors have different effects on survival
Authors: Suo Zhenhe , Risberg Bjørn , Kalsson Mats G. , Willman Kenneth , Tierens Anne , Skovlund Eva , Nesland Jahn M. 
Published: October 2002

AbstractOne hundred patients with breast carcinoma followed for 7–11 years were included in the present study of EGFR family members, using immunohistochemistry and RT‐PCR. By immunohistochemistry, 36%, 27%, 26%, and 82% of the tumours were positive for EGFR, c‐erbB‐2, c‐erbB‐3, and c‐erbB‐4. All the immunoreactive tumours were confirmed positive by RT‐PCR. Tumour size, histological grade, lymph node status, S‐phase fraction, and stage were confirmed to be significantly associated with both disease‐free and cancer‐specific survival in the present study. Methods of treatment, histological type, and ploidy had no significant effect on survival. Statistical analysis of EGFR family members in these tumours showed a significant association between c‐erbB‐2 expression and reduced disease‐free and cancer‐specific survival. c‐erbB‐4 expression was associated with a more favourable outcome. Co‐expression of c‐erbB‐2 and EGFR was associated with a worse prognosis. c‐erbB‐4 expression, however, showed an antagonistic effect on the clinical influence of c‐erbB‐2 expression. In conclusion, c‐erbB‐2 expression in breast carcinomas is associated with an unfavourable clinical course and EGFR expression has a synergistic effect. However, c‐erbB‐4 antagonizes the c‐erbB‐2 effect on clinical course in breast carcinomas. To achieve best results with immunotherapy against the c‐erbB‐2 receptor, clarifying the status of c‐erbB‐4 expression may be of significance. Copyright © 2001 John Wiley & Sons, Ltd.
Fractalkine expression in human renal inflammation
Authors: Cockwell Paul , Chakravorty Srabasti J. , Girdlestone John , Savage Caroline O. S. 
Published: October 2002

AbstractImmune and inflammatory human renal disease is associated with heavy mononuclear cell infiltration. The trafficking of these cells to extravascular sites is directed by local production of chemokines. Fractalkine is the first described cell‐surface anchored chemokine and has potent mononuclear cell‐directed adhesion and chemotactic properties. The purpose of this study was to analyse the expression and distribution of fractalkine in human renal inflammation. In situ hybridization and immunohistochemistry were used to study renal biopsies from 15 patients with predominant glomerular inflammation (vasculitic glomerulonephritis) and 15 with predominant tubular and interstitial inflammation (acute renal allograft rejection). Controls comprised non‐inflammatory glomerulonephritis and normal tissue. Fractalkine mRNA was predominantly expressed in the major compartment, glomerular or tubulointerstitial, affected by disease and with the strongest expression localized to vascular sites local to inflammation. In acute renal allograft rejection, there was increased expression of fractalkine mRNA by tubular epithelial cells. There was no expression of fractalkine by infiltrating leukocytes and there was only sparse expression in control tissue. Fractalkine mRNA expression correlated with infiltrating leukocyte subsets. Immunohistochemistry confirmed this pattern of expression, with serial section co‐localization showing fractalkine expression in areas with macrophage (CD68+) and T cell (CD3+) infiltrates. These expression patterns show that fractalkine is a strong candidate for directing mononuclear cell infiltration in human renal inflammation. Copyright © 2001 John Wiley & Sons, Ltd.
Expression of receptors for advanced glycation end‐products (RAGE) is closely associated with the invasive and metastatic activity of gastric cancer
Authors: Kuniyasu Hiroki , Oue Naohide , Wakikawa Atsuko , Shigeishi Hideo , Matsutani Norimasa , Kuraoka Kazuya , Ito Reiko , Yokozaki Hiroshi , Yasui Wataru 
Published: October 2002

AbstractThe receptor for advanced glycation end‐products (RAGE) is a newly recognized factor regulating cancer cell invasion and metastasis. This study investigated the expression of RAGE in gastric carcinomas and its association with invasion and metastasis. Of eight gastric cancer cell lines examined, seven constitutively expressed RAGE messenger ribonucleic acid (mRNA), MKN45 being the exception. RAGE protein expression of MKN28 cells treated with RAGE antisense S‐oligodeoxynucleotide was nine times less than that of sense S‐oligodeoxynucleotide‐treated cells. Growth of cells under RAGE antisense S‐oligodeoxynucleotide treatment was not different from that seen under sense S‐oligodeoxynucleotide treatment in MKN28 (a cell line producing high levels of RAGE) and MKN45 (a non‐RAGE‐expressing cell line). RAGE antisense S‐oligodeoxynucleotide treatment suppressed the invasive activity of RAGE‐positive MKN28 cells, as estimated by in vitro invasion assay. The number of MKN28 cells invading the type IV collagen‐coated membrane under RAGE antisense S‐oligodeoxynucleotide treatment was significantly lower than under RAGE sense S‐oligodeoxynucleotide treatment (p<0.0001). In contrast, antisense and sense S‐oligodeoxynucleotide‐treated RAGE‐negative MKN45 cells showed no difference. A wound‐healing assay showed that no RAGE antisense S‐oligodeoxynucleotide‐treated MKN28 cells migrated into the scraped area, whereas sense S‐oligodeoxynucleotide‐treated cells showed many budding nests in the scraped area. Immunohistochemistry of gastric carcinoma tissue showed that 62 (65%) of the 96 cases examined were RAGE‐positive and that poorly differentiated adenocarcinomas preferentially expressed RAGE protein (38/42, 90%) (p<0.0001). Strong RAGE immunoreactivity was also correlated with depth of invasion and lymph node metastasis (p<0.0001). RAGE‐positive cancer cells tended to be distributed at the invasive front of primary tumours and were detected in all metastatic foci in lymph nodes. In contrast, a major RAGE ligand, amphoterin, was expressed in 82 (85%) of the 96 cases, regardless of histological type and disease progression. RAGE expression appears to be closely associated with invasion and metastasis in gastric cancer. Copyright © 2001 John Wiley & Sons, Ltd.
Angiogenic co‐operation of VEGF and stromal cell TP in endometrial carcinomas
Authors: Sivridis Efthimios , Giatromanolaki Alexandra , Anastasiadis Panagiotis , Georgiou Loukas , Gatter Kevin C. , Harris Adrian L. , Bicknell Roy , Koukourakis Michael I. 
Published: October 2002

AbstractVascular endothelial growth factor (VEGF) and thymidine phosphorylase (TP) are important angiogenic enzymes, inducing new blood vessel formation in many human malignancies. In this study, the immunohistochemical expression of the two molecules was analysed in a series of 121 endometrial carcinomas. VEGF was expressed exclusively in cancer cells, while TP expression was shown in cancer cells (TPcc) and in stromal cells (TPsc) of both fibroblastic and myometrial origin. In all cases, enzymatic detection was particularly evident at the invading tumour front. At this site, TPsc, but not VEGF, expression was associated with non‐endometrioid‐type carcinomas, high tumour grade, deep myometrial invasion, and advanced stage. VEGF, but not TP, expression was related to increased angiogenesis (p=0.01). Double stratification of the two factors, however, marked VEGF/TPsc co‐expression as the most potent angiogenic phenotype (p=0.008), suggesting a synergistic function. Survival analysis revealed that VEGF and TPsc, whether expressed alone or in combination, define poor prognosis. In multivariate analysis, however, stage of disease (p<0.0001, t‐ratio 4.4) and VEGF expression (p=0.01, t‐ratio 2.4) were the most important prognostic variables. Furthermore, VEGF expression emerged as the only independent prognostic variable in stage I endometrial carcinomas (p=0.04, t‐ratio 1.9). This was not shown for TP, probably because of its close association with histopathological parameters. In conclusion, VEGF is a major angiogenic factor in endometrial carcinomas and an independent prognostic factor in stage I endometrial disease. TP is not an effective contributor to the angiogenic process, but is associated with aggressive histological features. The two factors, when co‐expressed, play a co‐operative role in the induction of angiogenesis. Copyright © 2002 John Wiley & Sons, Ltd.
A novel bcl‐1/JH breakpoint from a patient affected by mantle cell lymphoma extends the major translocation cluster
Authors: Degan Massimo , Doliana Roberto , Gloghini Annunziata , Di Francia Raffaele , Aldinucci Donatella , Mazzocut‐Zecchin Linda , Colombatti Alfonso , Attadia Vincenza , Carbone Antonino , Gattei Valter 
Published: October 2002

AbstractMantle cell lymphoma (MCL) is a B‐lymphocytic malignancy frequently associated with the presence of the t(11;14) chromosomal translocation. By using a polymerase chain reaction (PCR) strategy to detect breakpoints within the major translocation cluster (MTC), an unexpectedly large product (about 1.1 kb by using first‐round bcl‐1/JH primers) has been identified in one out of 16 patients harbouring the t(11;14) translocation. Sequence analysis of the atypical PCR product, re‐amplified and cloned with second‐round primers, revealed a 459 bp portion corresponding exactly to the 3′‐end segment of the MTC, followed by a sequence of 433 bp that lacked homology with any previously known sequence. PCR experiments using DNA from healthy donors identified that fragment as an extension of MTC fused, through a N‐region of seven nucleotides, to the JH4 region of IgH gene. A computer‐based search of the novel MTC portion aimed at detecting potential recombination motifs revealed the presence of several 4‐bp sequences (5′‐CCAG‐3′ or its complement 5′‐CTGG‐3′), one of them within seven nucleotides from the putative breakpoint, known to play a role in non‐homologous recombination events at the Ig loci. The recognition of this novel breakpoint may have important implications for the diagnosis and detection of minimal residual disease in t(11;14)‐positive lymphomas. Copyright © 2002 John Wiley & Sons, Ltd.
Frequent genomic imbalances in chromosomes 17, 19, and 22q in peripheral nerve sheath tumours detected by comparative genomic hybridization analysis
Authors: Koga Takamasa , Iwasaki Hiroshi , Ishiguro Masako , Matsuzaki Akio , Kikuchi Masahiro 
Published: October 2002

AbstractComparative genomic hybridization (CGH) was used to detect changes in relative chromosome copy number in 50 cases of peripheral nerve sheath tumour (PNSTs), including nine malignant peripheral nerve sheath tumours (MPNSTs), 27 neurofibromas (with three plexiform neurofibromas) and 14 schwannomas. Chromosome imbalances were frequently detected in benign as well as malignant PNSTs. In both NF1‐associated and sporadic MPNSTs, the number of gains was higher than the number of losses, suggesting proto‐oncogene activation during MPNST progression. NF1‐asociated MPNSTs exhibited gains of chromosomes 17q and X (2/4 cases each), where as sporadic MPNSTs showed gains of chromosome 4q (3/5 cases). On the other hand, in benign neurofibromas and schwannomas, the number of losses was higher than the number of gains, suggesting a predominant role of tumour suppressor genes in tumourigenesis. Both sporadic and NF1‐associated neurofibromas exhibited losses at chromosome 22q in more than 50% of cases. These chromosomal regions may contain common chromosomal abnormalities characteristic of both types of neurofibromas. In NF1‐associated neurofibromas, most frequent losses were found in chromosomes 17 [17p11.2–p13 in nine cases (60%); 17q24–25 in 6 cases (40%)] and 19 [19p13.2 in eight cases (53%); 19q13.2–qter in eight cases (53%)], whereas in sporadic neurofibromas and schwannomas losses of chromosomes 17 and 19 were detected in less than 50% of cases. Since this 17p11.2–p13 region is known to contain the tumour suppressor gene TP53, patients with NF1 may be at high risk of malignant neoplasms including MPNSTs. Gains were more frequently detected in plexiform neurofibromas (2/3 cases) than other benign tumours, suggesting proto‐oncogene activation in tumourigenesis of plexiform neurofibroma. The significance of the losses of chromosome 19 in these cases is not clear at present, but in NF1‐associated neurofibromas, the presence of some as yet unknown tumour suppressor genes on chromosome 19 cannot be ruled out. Copyright © 2002 John Wiley & Sons, Ltd.
Mast cells in the pathogenesis of chronic back pain: a hypothesis
Authors: Freemont Anthony J. , Jeziorska Maria , Hoyland Judith A. , Rooney Paul , Kumar Shant 
Published: October 2002

AbstractThe pathophysiology of chronic low back pain is poorly understood, mainly because it is difficult to study experimentally or objectively. Recently it has been found that there is a relationship between neovascularization and innervation of the usually avascular and aneural intervertebral disc at the sites of discogenic pain. These data, together with the recognized involvement of mast cells in tissue repair, in the induction of angiogenesis, and in the production of and response to neurotrophic stimuli such as nerve growth factor, has suggested the hypothesis that mast cells may have a causative role in chronic low back pain. If so, the mast cell may represent an attractive therapeutic target. Copyright © 2002 John Wiley & Sons, Ltd.
Detection of Epstein–Barr virus genome within thymic epithelial tumours in Taiwanese patients by nested PCR, PCR in situ hybridization, and RNA in situ hybridization
Authors: Chen Paul Chih‐Hsueh , Pan Chin‐Chen , Yang An‐Hang , Wang Liang‐Shun , Chiang Hung 
Published: October 2002

AbstractEpstein–Barr virus (EBV) is known to be associated with a variety of tumours, including Burkitt's lymphoma, nasopharyngeal carcinoma, and some carcinomas of other organs with similar lymphoepithelioma‐like features. The association between EBV and thymic epithelial tumours is inconclusive, as reports in this regard are not entirely consistent and the methods employed are of different sensitivity and specificity. This study examined 78 thymomas and 21 thymic carcinomas in Taiwanese patients, to detect the viral genome at both DNA and RNA levels. The tissue blocks were first screened by nested polymerase chain reaction (PCR) targeting on the first tandem internal repeats. The positive cases were further submitted for viral localization by in situ PCR insitu hybridization (ISH) and Epstein–Barr‐encoded RNA‐1 (EBER‐1) ISH. None of the thymomas showed a detectable EBV genome. Eight thymic carcinomas were positive for EBV by nested PCR, of which six displayed nuclear signals within the tumour cells by in situ PCR ISH and/or RNA ISH, one displayed signals within the lymphocytes, and one showed no discernible in situ signals. Most of them exhibited a lymphoepithelioma‐like morphology. These results show that nested PCR is a sensitive method for screening the EBV genome in thymic epithelial tumours. In situ PCR ISH is reliable for localization of the virus, in addition to EBER‐1 RNA ISH. Thymomas are not related to EBV, even in this endemic area. Thymic carcinomas, especially the lymphoepithelioma‐like thymic carcinomas, are more often associated with the virus. Copyright © 2002 John Wiley & Sons, Ltd.
Pancreatic stem cells
Authors: Bonner‐Weir Susan , Sharma Arun 
Published: October 2002

Abstractβ‐cell replacement therapy via islet transplantation has had renewed interest, due to the recent improved success. In order to make such a therapy available to more than a few of the thousands of patients with diabetes, new sources of insulin‐producing cells must be readily available. The recent conceptual revolution of the presence of adult pluripotent stem cells in bone marrow and in most, if not all, organs suggests that adult stem cells may be a potential source of insulin‐producing cells. Pancreatic stem/progenitor cells or markers for these cells have been sought in both islets and ducts. There is considerable evidence that such cells exist and several candidate cells have been reported. However, no clearly identifiable adult pancreatic stem cell has been found as yet. The putative pancreatic stem cells will be the focus of this review. Copyright © 2002 John Wiley & Sons, Ltd.