bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Multi‐Model Approach for the Efficient Solution of Differential‐Algebraic Boundary Value Problems
Authors: Callies R. 
Published: June 2004

AbstractA multi‐model approach is presented which allows the efficient and stable coupling between high precision algorithms for DAE boundary value problems arising from constrained optimal control problems and model data obtained with rather low accuracy from finite element solutions of PDEs. A model hierarchy with increasing approximation accuracy serves as an intermediate layer. Numerical efficiency is demonstrated for an example from flight mechanics.
Index Analysis of a Nonlinear PDAE System Describing a Molten CarbonateFuel Cell
Authors: Chudej Kurt , Petzet Verena , Scherdel Sabine , Pesch Hans Josef , Schittkowski Klaus , Heidebrecht Peter , Sundmacher Kai 
Published: June 2004

AbstractWithout combustion, molten carbonate fuel cells (MCFC) convert chemical energy contained in fuel and oxidizer to electric energy via electro‐chemical reaction. Performance and service life of MCFCs depends on its operating temperature. So control of the operation temperature within a specified range and reducing temperature fluctuations is highly desirable. In a very first step towards this goal prior to numerical simulations an index analysis of the partial differential‐algebraic equation system (PDAE) is given. Some numerical solutions can be found in [4].
Runge‐Kutta methods for monotone differential and stochastic equations
Authors: Kloeden Peter , Schropp Johannes 
Published: June 2004

AbstractRunge‐Kutta methods which preserve monotonicity for deterministic ordinary differential equations also preserve montonicity for random differential equations albeit with reduced order. However, the only one‐step numerical methods which preserve the montone structure of a monotone stochastic differential equation are the strong Taylor schemes of strong order 0:5 and 1:0.
Uniform convergence of a finite difference scheme for a system of coupledreaction‐diffusion equations
Authors: Linss Torsten , Madden Niall 
Published: June 2004

AbstractWe study a system of coupled reaction‐diffusion equations. The equations have diffusion parameters of different magnitudes associated with them. Near each boundary, their solution exhibit two overlapping layers. A difference scheme on layer‐adapted piecewise uniform meshes is used to solve the system numerically. We show that the scheme is almost second‐order convergent, uniformly in both perturbation parameters, thus improving previous results [3].
Time integration of index 1 DAEs with Rosenbrock methods using Krylovsubspace techniques
Authors: Wensch J. , Podhaisky H. , Hartmann S. 
Published: June 2004

AbstractThe derivation of Rosenbrock‐Krylov methods for index 1 DAEs involves two well known techniques: a limit process which transforms a singular perturbed ODE to an index 1 DAE and the use of Krylov iterations instead of direct linear solvers for the stage equations. We show that our derived class of Rosenbrock‐Krylov schemes is independent of the order in which we apply these techniques. We also conclude that for convergence a rather accurate solution of the algebraic part is always needed.
Solving Multi‐Scale problems with heterogeneous finite difference methods
Authors: Abdulle Assyr 
Published: June 2004

AbstractMulti‐scale differential equations are problems in which the variables can have different length scales. The direct numerical solution of differential equations with multiple scales is often difficult due to the work for resolving the smallest scale. We present here a strategy which allows the use of finite difference methods for the numerical solution of parabolic multi‐scale problems, based on a coupling of macroscopic and microscopic models for the original equation.
Evidence for acid‐induced loss of Cdx2 expression in duodenal gastric metaplasia
Authors: Faller Gerhard , Dimmler Arno , Rau Tilman , Spaderna Simone , Hlubek Falk , Jung Andreas , Kirchner Thomas , Brabletz Thomas 
Published: June 2004

AbstractGastric metaplasia in the duodenum (GMD) is characterized by transdifferentiation of intestinal epithelial cells into gastric foveolar cells within the duodenal mucosa. GMD is often associated with duodenal ulceration. Higher duodenal acidity due to increased gastric acid output into the duodenum has been implicated in the development of GMD. Intestinal development and homeostasis are controlled by the homeobox transcription factor Cdx2, which is considered to be the master regulator of intestinal differentiation. Using immunohistochemistry, the present study shows that GMD is associated with loss of expression of Cdx2 and its target gene product sucrase‐isomaltase. Quantitative RT‐PCR experiments using the intestinal cell line Caco2 revealed that Cdx2 and sucrase‐isomaltase were down‐regulated and gastric mucins MUC5AC and MUC6 were up‐regulated under acidic culture conditions. Thus, it is suggested that increased acid exposure leads to GMD by impairing the transcription of Cdx2 and subsequently that of its intestine‐specific target genes. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Expression of Sonic hedgehog pathway genes is altered in colonic neoplasia
Authors: Oniscu Anca , James Roberta M , Morris Robert G , Bader Scott , Malcomson Roger DG , Harrison David J 
Published: June 2004

AbstractThe Hedgehog (Hh) signalling pathway is crucial for normal development and patterning of numerous human organs including the gut. Hh proteins are also expressed during gastric gland development and gastric epithelial differentiation in adults. Recently, dysregulation of these developmentally important genes has been implicated in cancer, leading to the present study of the expression of Hh signalling proteins in colon cancer. In this study, normal colon and colonic lesions (hyperplastic polyp, adenoma, and colonic adenocarcinoma) were examined by immunohistochemistry using antibodies against Hh signalling molecules: the secreted protein Sonic hedgehog (SHH), its receptor Patched (PTCH), and the PTCH‐associated transmembrane protein Smoothened (SMOH). The study shows that Hh signalling pathway members are expressed in normal colonic epithelium. SHH was expressed at the top of the crypts and in a few basally located cells, while PTCH was detected in the neuroendocrine cells and SMOH at the brush border of superficial epithelium. RT‐PCR analysis of laser‐microdissected crypts from normal human colon confirmed that mRNAs encoding these proteins were expressed in colonic epithelium. Expression of SHH, PTCH, and SMOH was up‐regulated in hyperplastic polyps, adenomas, and adenocarcinomas of the colon, and SHH expression correlated with increased expression of the proliferation marker Ki‐67 in all lesions examined. To address whether the Hh signalling pathway is functional in the gut, the effect of Shh on epithelial cells in vitro was explored by treating primary murine colonocytes with either Shh peptide or neutralizing anti‐Shh antibody. The proportion of cells in the S‐phase was assessed by bromodeoxyuridine (BrdU) incorporation. It was found that exogenous Shh promotes cell proliferation in colonocytes, while anti‐Shh inhibits proliferation, suggesting that Shh is required during proliferation of epithelial cells in vitro. It is suggested that SHH is required during epithelial proliferation in the colon and that there is a possible role for Hh signalling in epithelial colon tumour progression in vivo. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Adventure therapy for adolescents with cancer
Authors: Stevens Bonnie , Kagan Susan , Yamada Janet , Epstein Iris , Beamer Madelyn , Bilodeau Mario , Baruchel Sylvain 
Published: June 2004

AbstractThe objective of this study was to describe adolescents' with cancer experience in an adventure therapy program from a health related quality of life (HRQL) perspective. A qualitative descriptive research method was used. Eleven adolescents and five health professionals participated in a guided group adventure therapy expedition in a remote area of Canada. The expedition was videotaped and data were collected using an unstructured interview format with both adolescents and health professionals. Emerging themes were identified using a qualitative descriptive exploratory analysis. Four major themes and related sub‐themes were generated. The major themes were: developing connections, togetherness, rebuilding self‐esteem, and creating memories. Adventure therapy was viewed by the adolescents and health care professionals as a positive experience with multiple benefits. This preliminary research will contribute to an understanding of adolescents' experiences with cancer and provide a basis for future studies evaluating the impact of adventure therapy on HRQL. © 2004 Wiley‐Liss, Inc.
Patterns of distress in parents of children undergoing stem cell transplantation
Authors: Phipps Sean , Dunavant Maggi , Lensing Shelly , Rai Shesh N. 
Published: June 2004

AbstractParents (N = 151) of children undergoing bone marrow or stem cell transplantation (BMT) were assessed in a prospective, longitudinal design with repeated measures of distress (mood disturbance, perceived stress, caregiver burden). Parents were assessed weekly from admission for BMT (week‐1) through week +6 post‐BMT, followed by monthly assessments through month +6. Concurrent measures of child distress (somatic distress, mood disturbance) were also obtained by parent and child report. Parents demonstrate modest, but significant elevations in distress, particularly during the early period from admission through week +3. Elevations in parental distress are transient, and appear to be largely resolved by 4–6 months post‐BMT. Parental distress was unrelated to child age, gender, diagnosis, or type of transplant, but was significantly related to parental socioeconomic status (SES). Parents from lower SES backgrounds reported greater levels of distress throughout the BMT process. Moderate correlations were observed between measures of parent and child distress, and level of child distress at the time of admission for BMT was predictive parental distress trajectories across the acute phase of BMT. These findings point to appropriate targets for intervention to reduce transplant‐related distress. © 2004 Wiley‐Liss, Inc.
Central diabetes insipidus as presenting symptom of Langerhans cell histiocytosis
Authors: Prosch Helmut , Grois Nicole , Prayer Daniela , Waldhauser Franz , Steiner Manuel , Minkov Milen , Gadner Helmut 
Published: June 2004

AbstractBackground and ObjectivesCentral diabetes insipidus (CDI) is a rare disorder associated with various underlying diseases. Among the systemic diseases that may cause CDI, Langerhans cell histiocytosis (LCH) is the most common. Therefore, in patients with endocrinologically proven CDI, a comprehensive diagnostic evaluation is crucial to identify possible extracranial sites of LCH. The goal of the diagnostic evaluation is to yield histopathological proof of the underlying disease. If possible, this histopathological proof should be provided by a biopsy of extracranial lesions to avoid a potentially hazardous biopsy of the pituitary stalk.Study DesignIn this retrospective study we included 54 patients registered at the LCH study reference center in whom the onset of CDI preceded the diagnosis of LCH, and we investigated their presentation and course to define a clinical pattern characteristic for LCH.ResultsIn 49/54 patients (91%) the detection and biopsy of extracranial lesions led to the diagnosis of LCH. The most frequently involved organs were bones, skin, and lungs; 86% of the patients with bone lesions had skull lesions. In 18% of the patients extracranial lesions were already found at presentation of CDI, in another 51% of the patients extracranial lesions were found within 1 year from onset of CDI.ConclusionsThese observations underline that a comprehensive search for extracranial lesions at presentation and during the first year thereafter may help to achieve a specific diagnosis without a pituitary stalk biopsy. © 2004 Wiley‐Liss, Inc.
Impact of location on outcome in children with low‐grade oligodendroglioma
Authors: Peters Ove , Gnekow A.K. , Rating D. , Wolff J.E.A. 
Published: June 2004

AbstractBackgroundChildhood low‐grade oligodendroglioma (WHO grade II) are rare. No controlled pediatric study has been published, to generate high level evidence for the best treatment. Therefore, we retrospectively analyzed data available from pediatric patients.ProcedureWe pooled data from two prospective German multicentre studies (HIT‐DOK and HIT‐LGG). Eligibility criteria were: (1) primary neoplasm, (2) histology of pure oligodendroglioma WHO grade II, (3) intracranial location, (4) age <18 years, (5) date of diagnosis: 1990–2002, (6) observation time >6 months. The outcome was analyzed by using the SPSS®‐software.ResultsNineteen boys and 13 girls were eligible (median age 10.3 years). The tumor locations included: 26 peripheral tumors (23 cerebral hemisphere, 3 cerebellum), and 6 central tumors (4 thalamus, 1 frontal mesencephalon, 1 basal ganglia). Resections were classified as complete in 18 (14 cerebral hemispheres, 3 cerebellum, 1 thalamus) and less than complete in 14 patients (3 subtotal resections, 8 partial resections, 3 biopsy). The 5‐year event‐free survival (EFS) and overall survival (OS) rates of all patients were 81.3 and 84.4%, respectively (median observation time 3.8 years). All of the 26 children with peripheral tumors were alive with no tumor progression, but five of six patients with central tumors died of disease (median time to death 1.6 years). This survival difference was statistically significant for EFS (P < 0.0001) and OS (P < 0.0001). The difference between completely resected versus incompletely resected tumors was far less striking (P > 0.06).ConclusionsThe outcome of children with centrally located low‐grade oligodendroglioma is particularly poor, while tumors of the cerebral hemispheres and cerebellum carry an excellent prognosis, even with minor tumor resection. © 2004 Wiley‐Liss, Inc.
Preparation and nonisothermal crystallization behavior of polyamide 6/montmorillonite nanocomposites
Authors: Tjong S. C. , Bao S. P 
Published: June 2004

AbstractPolyamide 6 (PA6)/montmorillonite (MMT) nanocomposites were prepared via melt intercalation. The structure, mechanical properties, and nonisothermal crystallization kinetics of PA6/MMT nanocomposites were investigated by X‐ray diffraction (XRD), tensile and impact tests, and differential scanning calorimetry (DSC). Before melt compounding, MMT was treated with an organic surfactant agent. XRD traces showed that PA6 crystallizes exclusively in γ‐crystalline structure within the nanocomposites. Tensile measurements showed that the MMT additions are beneficial in improving the strength and the stiffness of PA6, at the expense of tensile ductility. Impact tests revealed that the impact strength of PA6/MMT nanocomposites tended to decrease with increasing MMT content. The nonisothermal crystallization DSC data were analyzed by Avrami, Ozawa, modified Avrami‐Ozawa, and Nedkov methods. The validity of these empirical equations on the nonisothermal crystallization process of PA6/MMT nanocomposites is discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2878–2891, 2004
ANSI/IEEE 1471 and systems engineering
Authors: Maier Mark W. , Emery David , Hilliard Rich 
Published: June 2004

AbstractANSI/IEEE Standard 1471‐2000 is the Recommended Practice for Architectural Description of Software‐Intensive Systems, developed by the IEEE's Architecture Working Group (AWG) under the sponsorship of the Software Engineering Standards Committee of IEEE. ANSI/IEEE 1471‐2000 is the first formal standard to address the content and organization of architectural descriptions. [A wide variety of architecture frameworks exist as de facto standards in particular communities, but ANSI/IEEE 1471 is the first formal standard in the sense of being a product formally approved by a recognized standards body.] The standard defines the structure and content of an Architectural Description (AD) and incorporates a broad consensus on best practices for such descriptions. Although ANSI/IEEE 1471‐2000 was conceived as a software‐focused standard, this article argues that it is equally applicable to any system; hence appropriate for use as a part of systems engineering to describe system architectures. This article reviews the concepts of ANSI/IEEE 1471‐2000, the rationale for their selection, and demonstrates its application in systems engineering. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 257–270, 2004
Factors mediating the effect of gender on ninth‐grade Turkish students' misconceptions concerning electric circuits
Authors: Sencar Selen , Eryilmaz Ali 
Published: June 2004

AbstractThis study was designed to identify and analyze possible factors that mediate the effect of gender on ninth‐grade Turkish students' misconceptions concerning electric circuits. A Simple Electric Circuit Concept Test (SECCT), including items with both practical and theoretical contexts, and an Interest‐Experience Questionnaire about Electricity (IEQ) were administered to 1,678 ninth‐grade students (764 male, 914 female) after the completion of a unit on electricity to assess students' misconceptions and interests‐experiences about electricity. Results of the concept test indicated that general performances of the students were relatively low and that many students had misconceptions in interpreting electric circuits. When the data were analyzed using MANOVA and follow‐up ANOVAs, a gender difference for males was observed on the dependent variable of total scores on the 10 practical items; however, there was no significant gender difference on the dependent variable of total scores on the six theoretical items. Moreover, when the same data were analyzed using MANCOVA and follow‐up ANCOVAs, controlling students' age and interest‐experience related to electricity, the observed gender difference was mediated on the total scores on the practical items. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 603–616, 2004
Differences in cell migration of cultured pituitary cells from infantile and adult rats: participation of the extracellular matrix and epidermal growth factor
Authors: González Balby , Solano‐Agama Ma.del Carmen , González del Pliego Margarita , Mendoza‐Garrido Ma.Eugenia 
Published: June 2004

AbstractDuring early postnatal development in the rat, the tissue architecture of the pituitary gland shows changes, revealing an intense migration process of the cells. The aim of this work was to examine anterior pituitary cell migration over type I and III collagen as well as type IV collagen, of cultured pituitary cells from infantile rats and adult rats, and the participation of the epidermal growth factor in this process. Differences in cell migration rate over these two types of collagen substrates were observed at both ages, and all in all, three times more cells migrated over type I/III collagen than over type IV collagen. These data show the migration‐promoting role of type I/III collagen for pituitary cells. Furthermore, when infantile cells were challenged to migrate over bovine serum albumin, the migration rate diminished, and, on the contrary, adult cell migration was higher. However, over collagen, infantile cells increased their migration rate with epidermal growth factor stimulation and adult cells showed a decrease in migration when the growth factor was in the medium. During migration, pituitary cells associated and arranged in clusters. This behavior increased in the presence of epidermal growth factor in the infantile cultures. Moreover, epidermal growth‐factor‐stimulated infantile cells formed larger aggregates. Adult cells also showed associative behavior, but more cells were observed isolated than in cluster arrangements and the growth factor did not induce changes in this behavior. Results showed a difference in the response of cell migration and cell association capacity to epidermal growth factor after migration of infantile and adult pituitary cells. With these observations we propose that epidermal growth factor is a cell regulator of the pituitary tissue re‐arrangement process during the infantile period.
Endometrial thickness after misoprostol use for early pregnancy failure
Authors: Creinin M.D , Harwood B , Guido R.S , Fox M.C , Zhang J ,   for the NICHD Management of Early Pregnancy Failure Trial
Published: June 2004

AbstractObjectives: To assess if there was any potential relationship between endometrial thickness and final treatment outcome in women successfully treated with misoprostol for a first trimester anembryonic gestation, embryonic demise or fetal demise. Methods: Eighty women were treated with up to two doses of misoprostol 800 μg vaginally for early pregnancy failure. Subjects were scheduled to return 2 (range 1–4), 7 (range 5–9) and 14 (range 12–17) days after treatment. Transvaginal ultrasonography was performed at each follow‐up visit. Results: The median endometrial thickness at each of the follow‐up visits for women who had expelled the gestational sac was 14 mm, 10 mm, and 7 mm, respectively. The endometrial thickness at the first follow‐up visit exceeded 15 mm in 20 subjects (36%) and 30 mm in four subjects (7%). Only three women had a suction aspiration for bleeding after documented expulsion. The endometrial thickness for these women was 11, 13, and 14 mm at the first follow‐up visit. Conclusions: There is no obvious relationship between increasing endometrial thickness and the need for surgical intervention in women treated with misoprostol for early pregnancy failure.
The evolution of a quality of care approach for improving emergency obstetric care in rural hospitals in Nepal
Authors: Clapham S , Basnet I , Pathak L.R , McCall M 
Published: June 2004

AbstractWe describe the iterative process of developing a locally‐appropriate quality of care approach and its role in emergency obstetric care (EmOC) programming in Nepal. We describe the context of maternal health issues in Nepal, the rationale for developing a quality of care approach within a model to improve EmOC, and outline the outcomes and catalytic effects of the process. The lessons learned during the development of this approach are detailed. The program developed and implemented a quality of care approach at three district hospitals in Nepal. This resulted in improvements in the structure, process and outcomes of EmOC in these institutions. The process also resulted in improved understanding of quality of care approaches on both local and national levels and the creation of a Nepalese quality of care evaluation framework for maternity services. While the theoretical concept of quality of care is difficult to translate into a concrete approach, we used a process in rural hospitals in Nepal that created highly motivated teams and improved the overall functioning of these hospitals.