bluuebunny/crossref_metadata_2025 huggingface dataset:
Branching in high molecular weight polyhydroxyethers based on bisphenol A
Authors: Burchard Walther , Bantle Siegfried , Zahir Sheik A.
Published: April 2003

The polyaddition reaction of bisphenol A with the diglycidyl ether of bisphenol A is treated statistically on the basis of cascade theory to describe the branching process. The chain lengthening step is based on the reaction of the epoxide functional group with the phenolic hydroxyl group and leads to the formation of a 1,3‐diphenoxy‐2‐propanol link. The peculiar feature of this polyaddition reaction is the possibility of further addition of an epoxide to a secondary hydroxyl group to form branched molecules. This branching reaction does not, however, lead to a loss of hydroxyl groups since a new secondary hydroxyl group is created when an epoxide functional group reacts with a secondary hydroxyl group. Closed analytic expressions are derived for the weight‐average (Mw) and number‐average (Mn) molecular weights in terms of the mole ratio R = mb/ma and the extents of reaction of the functional groups α(phenolic hydroxyl), β(epoxide), and p(branching), i.e. the probability p that an epoxide group has reacted with a secondary hydroxyl group, where mb and ma are the mole fractions of the diglycidyl ether of bisphenol A and of bisphenol A, respectively. Consideration of a simple kinetic mechanism shows that α,β and ρ are related to the ratio b = k2/k1, where k1 and k2 are the rate constants of the chain lengthening step and the chain branching step, respectively. The equations derived for Mw and Mn as a function of a α allow the determination of the branching probability p (or the kinetic rate constant ratio b). An equation for the gel point (Mw → ∞) is given which states a relationship between αc and pc where the subcript c refers to the critical point of gelation. Thus location of the gel point and measurement of αc, either directly or by extrapolation on samples taken prior to gelation, enables p to be measured.
Initiation processes in polymerizations of alkyl cyanoacrylates by tertiary amines: Inhibition by strong acids
Authors: Pepper David Charles , Ryan Bernard
Published: April 2003

Polymerizations of butyl and ethyl cyanoacrylates, in the solvent THF, initiated by pyridine and other tertiary amines, are inhibited by strong acids, which cause well‐defined inhibition periods (ti) proportional to the concentration of acid added, but irrespective of its nature. The temperature and monomer concentration dependence of ti indicate that chain‐initiation is a composite sequence involving two or three successive additions of monomer. A detailed theory is proposed and used to evaluate the composite initiation rate constants over the temperature range 20°C to −80°C. The influence of steric factors on the initiation by pyridine, picolines and lutidine is exemplified and discussed.
Polymerisationsauslösung mit substituierten ethanen, 6. Polymerisation von methylmethacrylat mit verschiedenen tetraphenylethanen
Authors: Błedzki Andrezj , Braun Dietrich , Titzschkau Klaus
Published: April 2003

The polymerization of methyl methacrylate (MMA) was initiated with 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethane (TPPA), 1,1,2,2‐tetraphenyl‐1,2‐bis(trimethylsiloxy)ethane (TPSA), and 1,1,2,2‐tetraphenyl‐1,2‐dicyanoethane (TPCA). The polymerization with these initiators is characterised by three steps: in the first period oligomers from MMA and initiator radicals are formed by primary radical termination. These telechelics are effective initiators for the further free radical polymerization of MMA. After consumption of the initiator radicals with increasing conversion a normal polymerization occurs.
An isomorphism between moduli spaces of abelian varieties
Authors: Birkenhake Christina , Lange Herbert
Published: April 2003

In a previous paper we showed that for every polarization on an abelian variety there is a dual polarization on the dual abelian variety. In this note we extend this notion of duality to families of polarized abelian varieties. As a main consequence we obtain an involution on the set of moduli spaces of polarized abelian varieties of dimension g. In particular, the moduli spaces $ {\cal A}_{(d_{1}, \ldots, d_{g})} $ and $ {\cal A}_{\left( d_1, {{d_{1}d_{g} \over {d_{g-1}}}, \ldots, {d_{1}d_{g} \over {d_{2}}}}, d_{g}\right)} $ are canonically isomorphic.
Invariants for proper metric spaces and open Riemannian manifolds
Authors: Eichhorn Jürgen
Published: April 2003

We introduce uniform structures of proper metric spaces and open Riemannian manifolds, characterize their (arc) components, present new invariants like e.g. Lipschitz and Gromov–Hausdorff cohomology, specialize to uniform triangulations of manifolds and prove that the presence of a spectral gap above zero is a bounded homotopy invariant.
Infinitely many solutions for polyharmonic elliptic problems with broken symmetries
Authors: Lancelotti Sergio , Musesti Alessandro , Squassina Marco
Published: April 2003

By means of a perturbation argument devised by P. Bolle, we prove the existence of infinitely many solutions for perturbed symmetric polyharmonic problems with non–homogeneous Dirichlet boundary conditions. An extension to the higher order case of the estimate from below for the critical values due to K. Tanaka is obtained.
Generalized multivalued nonlinear quasivariational inclusions
Authors: Liu Zeqing , Kang Shin Min
Published: April 2003

In this paper, we introduce and study a few classes of generalized multivalued nonlinear quasivariational inclusions and generalized nonlinear quasivariational inequalities, which include many classes of variational inequalities, quasivariational inequalities and variational inclusions as special cases. Using the resolvent operator technique for maximal monotone mapping, we construct some new iterative algorithms for finding the approximate solutions of these classes of quasivariational inclusions and quasivariational inequalities. We establish the existence of solutions for this generalized nonlinear quasivariational inclusions involving both relaxed Lipschitz and strongly monotone and generalized pseudocontractive mappings and obtain the convergence of iterative sequences generated by the algorithms. Under certain conditions, we derive the existence of a unique solution for the generalized nonlinear quasivariational inequalities and obtain the convergence and stability results of the Noor type perturbed iterative algorithm. The results proved in this paper represent significant refinements and improvements of the previously known results in this area.
Duality of (1, 5)–polarized abelian surfaces
Authors: Melliez Franck
Published: April 2003

There is not many open questions about the moduli space of (1, 5)–polarized abelian surfaces and level structure, it has been carefully studied by Barth, Hulek and Moore in the 80's. The goal of this paper is to give a description of the moduli space of (1, 5)–polarized abelian surfaces (without level structure) up to duality. We prove that an open set of this moduli space is isomorphic to an open set of the moduli space of sextuplets of points on a complex projective line (up to homographies) and we study what happens on the boundary.
Bounded factorization property for Fréchet spaces
Authors: Terzioğlu Tosun , Zahariuta Vyacheslav
Published: April 2003

An operatorT∈L(E, F)factors over GifT=RSfor someS∈L(E, G) andR∈L(G, F); the set of such operators is denoted byLG(E, F). A triple (E, G, F) satisfiesbounded factorization property(shortly, (E, G, F) ∈ ℬ︁ℱ) ifLG(E, F) ⊂LB(E, F), whereLB(E, F) is the set of all bounded linear operators fromEtoF. The relationship (E, G, F) ∈ ℬ︁ℱ is characterized in the spirit of Vogt's characterisation of the relationshipL(E, F) =LB(E, F) [23]. For triples of K�othe spaces the property ℬ︁ℱ is characterized in terms of their K�othe matrices.

As an application we prove that in certain cases the relationsL(E, G1) =LB(E, G1) andL(G2, F) =LB(G2, F) imply (E, G, F) ∈ ℬ︁ℱ whereGis a tensor product ofG1andG2.
BV solutions of a singular diffusion equation
Authors: Yin J. X. , Li H. L. , Pang P. Y. H.
Published: April 2003

In this paper, we study discontinuous solutions of a partial differential equation of strongly degenerate parabolic type. A notion of weak solutions of BV class is proposed, and existence and uniqueness results are obtained.
High Temperature Construction Materials on the Basis of Nanodisperse Silicon Nitride
Authors: Zhilinska N. , Zalite I. , Grabis J. , Kladler G.
Published: April 2003

Si3N4‐Al2O3‐Y2O3, Si3N4‐TiN and Si3N4‐AIN‐Al2O3‐Y2O3 (β‐sialon) nanopowders with the specific surface area of 60–70 m2/g and average particle size of 30–50 nm have been prepared by plasmachemical synthesis. By means of the hot pressing method at 1850°C compact materials with fine‐grained structure were prepared from this powders as well as from mixture of Si3N4‐Al2O3‐Y2O3 with the second phase (10 wt.% SiC‐Si3N4, ZrO2, TiN nanopowder). Addition of the second phase to silicon nitride improves material strength.
Investigation of C/Si3N4 Nanocomposites
Authors: Balázsi C. , Wéber F. , Arató P.
Published: April 2003

Nanocrystalline carbon black and graphite micrograins have been added to silicon nitride starting powder and sintering additives (Al2O3 and Y2O3). These mixtures were mechanochemically activated several hours in a planetary type alumina ball‐mill in order to achieve a homogenous mass. As an alternative to nano‐ and micrograins, carbon fibres have been added to carbon free silicon nitride batches. Sinter‐HIP has been applied to rectangular bars which were earlier dry pressed. Structural and morphological analysis were performed on as‐prepared samples. Bending strength and elastic modulus have been found to be influenced by amount of carbon black and graphite introduced in silicon nitride matrix.
Wear and Creep Characteristics of a Carbon‐Derived Si3N4/SiC Micro/Nanocomposite
Authors: Kašiarová M. , Rudnayová E. , Kovalčík J. , Dusza J. , Hnatko M. , Šajgalík P. , Merstallinger A.
Published: April 2003

In the presented work some properties of a recently developed Si3N4/SiC micro/nanocomposite have been investigated. The material was tested using a pin on disc configuration. Under unlubricated sliding conditions using Si3N4 pin at 50 % humidity, the friction coefficient was in the range of 0,6 ‐ 0,7. The reduction of humidity resulted in a lower coefficient of friction, in vacuum the coefficient of friction had a value of about 0,6. The wear resistance in vacuum was significantly lower then that in air. The wear patterns on the Si3N4+SiC disc revealed that mechanical fracture was the wear controlling mechanism.

Creep tests were realized in four point bending configuration in the temperature interval 1200‐1400 °C at stresses 50,100 and 150 MPa and the minimal creep deformation rate was established for each stress level. The activation energy, established from the minimal creep deformation had a value of about 360 kJ/mol and the stress exponent values were in the range of 0.8‐1.28. From the achieved stress exponents it can be assumed that under the studied load/temperature conditions the diffusion creep was the most probable creep controlling mechanism.
Properties of new polyimide foams and polyimide foam filled honeycomb composites
Authors: Resewski C. , Buchgraber W.
Published: April 2003

New polyimide foams and polyimide foam filled honeycombs are currently being developed at NASA, its licensee Sordal Inc. (USA) and Newmet (UK) under the trade name Solrex®. These materials are foreseen for Space, Aerospace, Maritime & Medicine applications. In this paper selected properties of these new materials with different densities are described.

The investigated key properties are compression strength, thermal conductivity and moisture gain. The dependence of these properties on density, temperature and thermal cycling is discussed. Limits of the used characterisation methods are discussed. Possible applications are defined.
Improving the properties of aluminium alloys by retrogression and reageing
Authors: Robinson J. S.
Published: April 2003

Retrogression and reageing heat treatments offer the potential of improved tensile properties in combination with greatly increased resistance to stress corrosion cracking. The potential of this technique is reviewed with respect to the current application in the European and North American Aerospace Industry. To illustrate the performance increase associated with RRA treatments, the stress corrosion cracking performance of the established aerospace plate and forging alloy 7010 has been evaluated using an alternate immersion constant load tensile type test (ECSS‐Q‐70‐37A) Specimens were cut from a large aerospace rectilinear forging and tested in three different tempers, T652, T7452 and a retrogressed and reaged condition (RRA). In the T652 condition the material has been shown to be highly susceptible to intergranular corrosion and stress corrosion cracking. In the T7452 and RRA conditions 7010 showed much improved resistance to SCC but pitting corrosion resulted in failure of some specimens within the 30day requirement of the test standard.
Thermal Conductivity Measurement of Nanoparticle Based Solid Propellant Mixtures
Authors: Marmiroli B. , Manzoni G. , Frassine R.
Published: April 2003

A Miniaturised Pyrotechnic Initiator (MPI) is a device used to ignite a charge. It is reduced in scale in order to be suitable for application in miniaturised satellites. Miniaturising the system presents challenges requiring careful consideration of propellant selection. Thermal conductivity tests have been conducted on different mixtures of composite solid propellant materials in order to determine the thermal conductivity of the propellant in the temperature range 0‐100 °C and to study the effect of the presence of porosity and bubbles on the thermal conductivity of the propellant. The applicability of semiempirical Ziebland Relation to predict the thermal conductivity of the composite propellant once the values of the single components are known has been assessed. Furthermore, mixtures of Al and Potassium Perchlorate powders with different compression factors have been examined in order to understand the influence of the processing conditions on thermal conductivity
A Study of Environmentally Friendly Titanium Pretreatments for Adhesive Bonding to a Thermoplastic Composite
Authors: Leahy W. , Young T. , Buggy M. , Barron V.
Published: April 2003

The increased use of fibre reinforced polymer composites for aircraft structures have highlighted the need for reliable methods of bonding these materials to metallic components such as titanium. There is also a need for a simple test to evaluate adhesive bonds with dissimilar substrates, while under load and in a variety of environments. In this study the Boeing wedge test has been adapted for use with metal to composite adhesive bonds. A flexural rigidity matching approach was used with the addition of a backing beam to the composite coupon. The titanium adherends were surface pre‐treated using novel environmental benign methods, namely argon gas plasma and silicon sputtering. Sodium hydroxide anodisation, which is currently used industrially and alumina grit blasting were used as benchmarks. The composite, glass fire reinforced polyphenylene sulphide was alumina grit blasted. An environmental cycle was used to mimic a typical aircraft service cycle; joints were subjected to 24‐hour cycles of ambient, 60 °C water immersion, 60 °C dry and –55 °C dry for 12 days. Crack propagation and locus of failure were monitored after each cycle.
Kerbspannungen sind Biegespannungen – was sind gute und böse Kerben?
Authors: Mattheck C. , Scherrer M. , Tesari I.
Published: April 2003

Die Entstehung von Kerbspannungen in einem Bauteil kann durch die Vorstellung einer überlagerten Biegung anschaulich erklärt werden. Die gekrümmte Oberfläche der Kerbe kann als konkave Seite eines stark gekrümmten Biegeträgers angesehen werden. Die nichtlineare Biegespannungsverteilung des Biegeträgers überlagert sich mit der Nennspannung und erzeugt die Spannungskonzentration in der Kerbe. Zur Vermeidung solcher Kerbspannungen muss sich der Anstieg der Spannung in der Kerbe mit dem Abfall der Nennspannung kompensieren. Ein multilinearisiertes Modell der Kerbe veranschaulicht die Wechselwirkung zwischen Umlenkung des Kraftflusses und Querschnittsverbreiterung des Bauteils.
Fourier‐Motzkin elimination method in MOLP problems
Authors: Melachrinoudis Emanuel , Liu Songan
Published: April 2003

This paper introduces a method for finding the non‐dominated set in criterion space of an MOLP problem based on Fourier–Motzkin Elimination. The method incorporates a procedure that eliminates decision variables from constraints and transforms a feasible region from decision space to criterion space. While avoiding characterization of the efficient set in decision space, it finds the non‐dominated set in criterion space. After the decision maker's most preferred criterion vector has been identified, the corresponding efficient solutions can be found by backward substitution. The method was implemented in MATLAB using a tabular form and computational experiments were conducted. The results indicate that although the method performs well for relatively small problems, it can be computationally intensive for larger problems. Nonetheless, the method is intuitively appealing and it provides useful insights into the geometry and theory of MOLP. As such it makes it a valuable educational tool for students of multi‐criteria decision analysis. Copyright © 2003 John Wiley & Sons, Ltd.
A multicriteria assignment problem
Authors: Scarelli Antonino , Narula Subhash C.
Published: April 2003

Our objective in this paper is to propose a procedure for solving a multicriteria assignment problem. Given qualitative and quantitative data, the proposed procedure makes assignments taking into consideration the multicriteria aspect of the problem. As an illustrative example, we consider the assignment of referees to the football matches in an Italian championship. Copyright © 2003 John Wiley & Sons, Ltd.
Euclid: Strategic alternative assessment matrix
Authors: Tavana Madjid
Published: April 2003

The vast amount of information that must be considered to solve inherently ill‐structured and complex strategic problems creates a need for tools to help decision makers (DMs) recognize the complexity of this process and develop a rational model for strategy evaluation. Over the last several decades, a philosophy and a body of intuitive and analytical methods have been developed to assist DMs in the evaluation of strategic alternatives. However, the intuitive methods lack a structured framework for the systematic evaluation of strategic alternatives while the analytical methods are not intended to capture intuitive preferences. Euclid is a simple and yet sophisticated multiobjective value analysis model that attempts to uncover some of the complexities inherent in the evaluation of strategic alternatives. The proposed model uses a series of intuitive and analytical methods including environmental scanning, the analytic hierarchy process (AHP), subjective probabilities, and the theory of displaced ideal, to plot strategic alternatives on a matrix based on their Euclidean distance from the ideal alternative. Euclid is further compared to the quantitative strategic planning matrix (QSPM) in a real world application. The information provided by the users shows that Euclid can significantly enhance decision quality and the DM's confidence. Euclid is not intended to replace the DMs, rather, it provides a systematic approach to support, supplement, and ensure the internal consistency of their judgments through a series of logically sound techniques. Copyright © 2003 John Wiley & Sons, Ltd.
Modelling risk and uncertainty with the analytic hierarchy process
Authors: Millet Ido , Wedley William C.
Published: April 2003

This paper proposes methods for modelling risk and uncertainty with the analytic hierarchy process (AHP). We start by showing why benefit/risk ratios, as described in previous literature, might be an improper modelling approach. We then introduce prototypical case studies where risk plays a role in multicriteria decision making. These cases demonstrate how the AHP can be used to derive relative probabilities, multiple criteria outcome measures, risk criteria, and risk adjustment factors. Copyright © 2003 John Wiley & Sons, Ltd.
Homebound schooling is the least favorable option for continued education of adolescent cancer patients: A preliminary report
Authors: Searle Nancy S. , Askins Martha , Bleyer W. Archie
Published: April 2003

Background

With an overall objective to improve the educational programs of pediatric cancer patients, the purpose of this study was to compare the quality of educational experiences of adolescent cancer patients undergoing treatment while enrolled in hospital, homebound, or community schools.

Procedure

Ten students, 12–17 years of age at diagnosis, their parent and their teachers were interviewed with a structured list of open‐ended questions designed to assess their perceptions of their homebound, hospital, and community school experiences. The interviews were taped, transcribed, and analyzed using qualitative methods for recurring themes.

Results

High achieving students engaged in extracurricular activities prior to diagnosis performed well academically in all three schooling situations. Those less engaged in school prior to diagnosis did poorly in homebound schools, better in their community schools, and best in the hospital school.

Conclusions

Homebound learning during cancer therapy does not appear to be as meaningful as either hospital or community learning environments. Prior academic performance, as well as social, emotional, and health factors should be considered in selecting the most appropriate formal school environment for adolescent cancer patients. Med Pediatr Oncol 2003;40:380–384. © 2003 Wiley‐Liss, Inc.
Tube feeding and bone marrow transplantation
Authors: Hopman G.D. , Peña E.G. , le Cessie S. , van Weel M.H. , Vossen J.M.J.J. , Mearin M.L.
Published: April 2003

Background

Children undergoing bone marrow transplantation (BMT) have poor oral intake during the transplant period, caused mainly by the intensive therapy used for their conditioning. Nutritional support (NS) is almost always needed. Whenever possible, tube feeding (TF) is preferred to parenteral nutrition (PN) because its more physiologic and causes fewer complications. However, children undergoing BMT are usually parenterally fed. We, therefore, studied whether TF was tolerated in children undergoing BMT and whether the nutritional intake was adequate in comparison to PN.

Procedure

Two groups were compared: TF (n = 12) and PN (n = 22). If intolerance for TF occurred, additional or total PN was given. Nutritional status, intake, complications, and costs were assessed.

Results

Both groups had an adequate nutritional status and reached 85% of their nutritional requirements. TF was possible in 62% of the NS days and three children could be exclusively fed with TF. A longer pre‐transplant duration of TF seemed to increase the enteral tolerance. Gastrointestinal symptoms were equally frequent in TF as in PN, but cholestasis was less frequent in TF. The mean nutritional cost per child in the TF group was 440 US dollars less than in the PN group.

Conclusions

TF is possible and equal in efficacy to PN in children undergoing BMT, and may have budgetary benefits. Med Pediatr Oncol 2003;40:375–379. © 2003 Wiley‐Liss, Inc.
Germ cell tumours of the central nervous system in children—controversies in radiotherapy
Authors: Borg Martin
Published: April 2003

Background

Primary germ cell tumours (GCT) of the central nervous system (CNS) are rare tumours of children and adults. As few prospective, randomised trials have been published, management decisions are often based on retrospective and historical studies, histology, age, performance status, and extent of disease at diagnosis. This article reviews the current controversies in the radiotherapeutic management of primary GCT of the CNS.

Procedure

A computerised literature search was performed using the Medline database from 1975 to 2000, this being limited to publications written in the English language on CNS GCT in children up to the age of 16 years.

Results

Issues in radiation therapy currently undergoing review include the role of cranio‐spinal irradiation (CSI), radiation therapy field sizes, the radiation therapy dose, the extent of surgery in combination with radiotherapy, and the role and timing of chemotherapy in combination with radiotherapy.

Conclusions

The excellent outcome in children with pure germinoma of the CNS and the long‐term morbidity associated with standard therapy justifies attempts to limit both the total radiation dose and field sizes, with or without the addition of chemotherapy. The poorer outcome associated with non‐germinoma GCT justifies a more aggressive approach in children, combining chemotherapy, surgery and virgule, or radiation therapy, based on known prognostic factors. Med Pediatr Oncol 2003;40:367–374. © 2003 Wiley‐Liss, Inc.
Influence of high‐dose methotrexate therapy (HD‐MTX) on glomerular and tubular kidney function
Authors: Hempel Lutz , Misselwitz Joachim , Fleck Christian , Kentouche Karim , Leder Christiane , Appenroth Dorothea , Rost Michael , Zintl Felix
Published: April 2003

Background

The present investigation was intended to further clarify the mechanisms involved in renal dysfunction following high‐dose methotrexate (HD‐MTX) treatment.

Patients and Methods

Fifty eight predominately pediatric patients [39 male, 19 female; mean age 12.3 years (range 2.2–34.1)] suffering from acute lymphoblastic leukemia (ALL, n = 28), Non Hodgkins lymphoma (NHL, n = 13), osteosarcoma (n = 8), malignant brain tumor (n = 6), or an ALL relapse (n = 3), were prospectively examined. In the course of 220 infusions of HD‐MTX, glomerular and tubular renal function was determined by measuring proteinuria and glomerular filtration rate (GFR), as well as renal excretion of alpha‐1‐microglobulin (AMG) and N‐acetyl‐β‐D‐glucosaminidase (NAG). It was investigated whether there were differences in MTX toxicity in dependence on the administered dose (1, 5, or 12 g/m2 BSA), on the combination with other cytostatic agents (ifosfamide or cyclophosphamide), on the metabolism of MTX into 7‐OH‐MTX, and on pre‐treatment with MTX.

Results

The administration of HD‐MTX has no direct tubulotoxic effect. The disturbance in glomerular function was dose dependently and indicated by an increase in proteinuria as well as by a decrease in GFR; all changes were completely reversible and did not correlate to the metabolism of MTX to 7‐OH‐MTX. Increasing the number of MTX therapeutic cycles did not increase the nephrotoxicity of MTX.

Conclusion

MTX is not directly tubulotoxic. Its side effects on glomeruli are usually without clinical relevance. Med Pediatr Oncol 2003;40:348–354. © 2003 Wiley‐Liss, Inc.
Sperm cryopreservation in adolescents with newly diagnosed cancer
Authors: Postovsky Sergey , Lightman Abraham , Aminpour Dina , Elhasid Ronit , Peretz Monique , Arush Myriam Weyl Ben
Published: April 2003

Background

Referring male patients (pts) for pretreatment sperm cryopreservation (SCP) is a routine practice in adult oncology. Our aim was to evaluate the semen quality and feasibility of sperm cryopreservation in male adolescents diagnosed with cancer prior to the commencement of treatment.

Methods

All consecutive adolescents from 14 to 19 years of age with newly diagnosed cancer were referred to this study. The following parameters of semen analysis were investigated: (1) volume of collected sample (N ≥ 2.0 ml); (2) total sperm concentration (N ≥ 20x106/ml); (3) percentage of motile spermatozoa (N ≥ 50%). The results were compared with normal values characteristic of healthy young men.

Results

Sixty‐two attempts to collect sperm were made by the 27 adolescents. Of the 40/62 (64.5%) attempts, which resulted in a normal sperm count in each sample, only nine (22.5%) demonstrated normal sperm motility. Only 9/62 (14.5%) attempts resulted in normal sperm motility. Nineteen of 62 (30.6%) attempts produced a normal volume of ejaculate, while three pts were unable to produce any sperm. Only 4/62 (6.5%) attempts produced semen that could be considered normal in all the parameters.

Conclusions

Only a minority of adolescents newly diagnosed with cancer is able to produce sperm that can be considered normal, compared with healthy young men. Despite this, SCP should be offered and is a technically feasible procedure for these patients in light of the recent advances in assisted reproductive technologies. Further studies are required to develop treatment protocols for this group of pts to lessen damage to fertility function. Med Pediatr Oncol 2003;40:355–359. © 2003 Wiley‐Liss, Inc.
Intraoperative electron beam treatment for pediatric malignancies: The Ohio State University experience
Authors: Nag Subir , Tippin Douglas , Smith Shane , Bauer Connie , Ruymann Frederick B.
Published: April 2003

Purpose

To report the result of intraoperative electron beam radiation therapy (IOERT) in patients with extensive pediatric tumors.

Method

From October 1989 through June 2000, 13 children were treated with chemotherapy, maximal surgery, and 10–15 Gy IOERT at a total of 18 sites. IOERT was used for palliative purposes in 5 children with metastatic disease and in 3 others who were previously treated with external beam radiation (EBRT). The remaining five patients received definitive IOERT. Postoperative EBRT of 35.4–45 Gy was given in 5 patients.

Results

After a median follow‐up of 42 months (range = 18–63 months), 4 patients were alive and without evidence of disease. Overall and 3 year actuarial survival rates were 31% (4/13) and 26%, respectively. Local control was achieved at 13/18 sites (72%). Poor prognostic factors included metastatic disease, recurrent disease, and the absence of adjuvant EBRT. Two children with Wilms tumors had 100% local control, disease‐free survival, and overall survival without the addition of EBRT.

Conclusion

A boost dose of IOERT allows for reduction in the dose of EBRT, thereby limiting growth‐related morbidity without compromising local control or disease‐free survival. Except for Wilms tumors, which achieved 100% local control and disease‐free survival, adjuvant EBRT is necessary for successful local control and survival in children with soft tissue sarcomas. Based on this study and others, intraoperative irradiation should be considered for inclusion in prospective, multi‐institutional trials designed to treat localized malignancies in young children. Med Pediatr Oncol 2003;40:360–366. © 2003 Wiley‐Liss, Inc.
Late cardiotoxicity after bolus versus infusion anthracycline therapy for childhood cancers
Authors: Gupta Monesha , Steinherz Peter G. , Cheung Nai‐Kong , Steinherz Laurel
Published: April 2003

Objective

To compare the long‐term myocardial function of patients who had been treated with infusion anthracycline therapy (administered continuously over >24 hr, IG) versus bolus therapy (administered over <30 min, BG).

Methods

We selected 25 patients (BG) and 19 patients (IG) who had three or more years of disease free survival. We evaluated the echocardiograms for left ventricular shortening fraction (SF) obtained at baseline, within one year after the end of therapy (early follow‐up), and on long‐term follow‐up.

Results

The mean anthracycline dose in the BG was 385 mg/m2 and in the IG was 345 mg/m2 (P = 0.07). During therapy, one patient in BG and none in IG developed diminished SF. During early follow‐up, five of the 22 patients in BG and one of the 17 patients in IG developed diminished SF (P = 0.2). Of these five patients with diminished SF, three patients in BG and none in IG continued to have abnormally low SF long‐term. At mean of 7 years, five of the 25 patients in BG and two of the 19 in IG had diminished SF on (P = 0.7). Late left ventricular dilatation was seen in 8% in BG and 5% in IG (P = 1.0).

Conclusions

At mean of 7 years after end of therapy, diminished cardiac function was seen in 20% of the patient who had received bolus anthracycline compared to 11% of patients who had received it via infusion. This difference did not prove to be statistically significant. Med Pediatr Oncol 2003;40:343–347. © 2003 Wiley‐Liss, Inc.
Designing materials with prescribed elastic properties using polygonal cells
Authors: Diaz Alejandro R. , Bénard André
Published: April 2003

An extension of the material design problem is presented in which the base cell that characterizes the material microgeometry is polygonal. The setting is the familiar inverse homogenization problem as introduced by Sigmund. Using basic concepts in periodic planar tiling it is shown that base cells of very general geometries can be analysed within the standard topology optimization setting with little additional effort. In particular, the periodic homogenization problem defined on polygonal base cells that tile the plane can be replaced and analysed more efficiently by an equivalent problem that uses simple parallelograms as base cells. Different material layouts can be obtained by varying just two parameters that affect the geometry of the parallelogram, namely, the ratio of the lengths of the sides and the internal angle. This is an efficient way to organize the search of the design space for all possible single‐scale material arrangements and could result in solutions that may be unreachable using a square or rectangular base cell. Examples illustrate the results. Copyright © 2003 John Wiley & Sons, Ltd.
An integrated, finite element‐based process model for the analysis of flow, heat transfer, and solidification in a continuous slab caster
Authors: Moon C. H. , Hwang S. M.
Published: April 2003

An integrated, finite element‐based process model is presented for the prediction of full three‐dimensional flow, heat transfer, and solidification occurring in a continuous caster. Described in detail are the basic models for the analysis of turbulent flow and heat transfer in the liquid steel zone, in the zone of mixture of the liquid steel and solidified steel, and in the solidified zone. Then, the models are integrated to form a process model which can take into account the strong interdependence between the heat transfer behaviour and the flow behaviour. The capability of the process model to reveal the detailed aspects of turbulent flow, heat transfer, and solidification occurring in a continuous caster is demonstrated through a series of process simulations. Copyright © 2003 John Wiley & Sons, Ltd.
Optimal modal reduction of vibrating substructures
Authors: Barbone Paul E. , Givoli Dan , Patlashenko Igor
Published: April 2003

A structure which consists of a main part and a number of attached substructures is considered. A ‘model reduction’ scheme is developed and applied to each of the discrete substructures. Linear undamped transient vibrational motion of the structure is assumed, with general external forcing and initial conditions. The goal is to replace each discrete substructure by another substructure with a much smaller number of degrees of freedom, while minimizing the effect this reduction has on the dynamic behaviour of the main structure. The approach taken here involves Ritz reduction and the Dirichlet‐to‐Neumann map as analysis tools. The resulting scheme is based on a special form of modal reduction, and is shown to be optimal in a certain sense, for long simulation times. The performance of the scheme is demonstrated via numerical examples, and is compared to that of standard modal reduction. Copyright © 2003 John Wiley & Sons, Ltd.
Simultaneous surface and tetrahedron mesh adaptation using mesh‐free techniques
Authors: Rassineux A. , Breitkopf P. , Villon P.
Published: April 2003

We present a method to adapt a tetrahedron mesh together with a surface mesh with respect to a size criterion. The originality of our work lies in the fact that both surface and tetrahedron mesh adaptation are carried out simultaneously and that no CAD is required to adapt the surface mesh. The adaptation procedure consists of splitting or removing interior and surface edges which violate a given size criterion. The enrichment process is based on a bisection technique. In order to guarantee mesh conformity during the refinement process, all possible remeshing configurations of tetrahedra have been examined. Once the tetrahedron mesh has been adapted, surface nodes are projected on a geometrical model. The building of a surface model from discrete data has already been presented in this journal. The method is based on a mesh‐free technique called Hermite Diffuse Interpolation. Surface and volume mesh optimization procedures are carried out during the adaptation and at the end of the process to enhance the mesh. Copyright © 2003 John Wiley & Sons, Ltd.
Coarsening unstructured meshes by edge contraction
Authors: Ollivier‐Gooch Carl
Published: April 2003

A new unstructured mesh coarsening algorithm has been developed for use in conjunction with multilevel methods. The algorithm preserves geometrical and topological features of the domain, and retains a maximal independent set of interior vertices to produce good coarse mesh quality. In anisotropic meshes, vertex selection is designed to retain the structure of the anisotropic mesh while reducing cell aspect ratio. Vertices are removed incrementally by contracting edges to zero length. Each vertex is removed by contracting the edge that maximizes the minimum sine of the dihedral angles of cells affected by the edge contraction. Rarely, a vertex slated for removal from the mesh cannot be removed; the success rate for vertex removal is typically 99.9% or more.

For two‐dimensional meshes, both isotropic and anisotropic, the new approach is an unqualified success, removing all rejected vertices and producing output meshes of high quality; mesh quality degrades only when most vertices lie on the boundary. Three‐dimensional isotropic meshes are also coarsened successfully, provided that there is no difficulty distinguishing corners in the geometry from coarsely‐resolved curved surfaces; sophisticated discrete computational geometry techniques appear necessary to make that distinction. Three‐dimensional anisotropic cases are still problematic because of tight constraints on legal mesh connectivity. More work is required to either improve edge contraction choices or to develop an alternative strategy for mesh coarsening for three‐dimensional anisotropic meshes. Copyright © 2003 John Wiley & Sons, Ltd.
Generalized Lagrange functions and weighting coefficient formulae for the harmonic differential quadrature method
Authors: Fung T. C.
Published: April 2003

In the harmonic differential quadrature method, truncated Fourier series comprising the trigonometric functions are used to approximate the solutions. The generalized Lagrange functions composed of trigonometric functions are constructed as interpolation functions so that the unknowns are the function values, rather than the Fourier coefficients. In the spirit of the differential quadrature method, the derivatives at a sampling grid point are expressed as weighted linear sums of function values at all the sampling grid points. It is shown that the corresponding weighting coefficients of higher order derivatives can be evaluated recursively and the general explicit formulae are given in this paper. The differential quadrature analog of the governing equations can then be established easily at the sampling grid points. For the periodic boundary value problems, the periodic boundary conditions are satisfied automatically and no other boundary conditions are required in general. It is also shown that the harmonic differential quadrature method is related to the trigonometric collocation method and the harmonic balance method. Numerical examples are given to illustrate the validity and efficiency of the present method. Copyright © 2003 John Wiley & Sons, Ltd.
Tumour suppressor gene expression correlates with gastric cancer prognosis
Authors: Lee Hye Seung , Lee Hyeon Kook , Kim Hee Sung , Yang Han‐Kwang , Kim Woo Ho
Published: April 2003

The loss of tumour suppressor genes (TSGs) is a key event in many human cancers, including gastric carcinoma. Many TSG candidates have been studied, but their roles in gastric carcinogenesis remain unclear. To clarify the clinical significance of TSG expression in gastric carcinoma, the expression of various TSG candidates (p53, E‐cadherin, FHIT, smad4, rb, VHL, PTEN, MGMT, p16, and KAI1), as well as other proteins (bcl‐2, MUC1, MUC2, MUC5AC, MUC6, CEA, CD44, β‐catenin, C‐erbB2, and cyclin B2), was evaluated immunohistochemically in 329 consecutive gastric carcinomas using the tissue array method. The overexpression of p53 and MUC1 (p < 0.01) and the loss of expression of smad4 (p = 0.04), FHIT (p = 0.03), MGMT (p = 0.01), E‐cadherin, KAI1, and PTEN (p < 0.01) were found to be significantly associated with poor gastric carcinoma prognosis. Seven out of eight survival‐associated proteins were found to be protein products of TSGs. The gastric carcinomas were divided into five groups according to the grade of alteration in TSG expression. No TSG expression loss was found in 32 cases (TSG1). One TSG loss was found in 47 cases (TSG2), two in 67 cases (TSG3), three or four in 64 cases (TSG4), and five, six, or seven in 38 cases (TSG5). The grade of TSG expression was confirmed to be significantly associated with WHO classification (p = 0.04), pTNM stage, lymphatic invasion, and patient survival (p < 0.01 for the latter three). By multivariate analysis, the grade of TSG expression was found to be significantly and independently associated with patient survival (p < 0.01). In conclusion, the findings of this study suggest that the cumulative loss of TSG expression in gastric carcinoma is important in determining patient survival. Copyright © 2003 John Wiley & Sons, Ltd.
The angiogenic peptide vascular endothelial growth factor (VEGF) is expressed in chronic sacral pressure ulcers
Authors: Pufe Thomas , Paulsen Friedrich , Petersen Wolf , Mentlein Rolf , Tsokos Michael
Published: April 2003

Chronic decubital lesions have a limited potential to heal. Evidence suggests that a lack of local revascularization is involved in this aetiology. The present study investigated the expression of one of the most important angiogenic factors, the vascular endothelial growth factor (VEGF), in different regions of sacral chronic decubital lesions and in normal skin by immunohistochemical, biochemical, molecular, and cell biology methods. To elucidate some of the factors responsible for the induction of VEGF in chronic skin ulcers, cultured fibroblasts were exposed to hypoxia and/or growth factors. In the central part (zone I) of chronic ulcers and in normal skin, immunostaining for VEGF remained largely negative. However, VEGF could be immunostained in cells in the granulation tissue adjacent to central necrosis (zone II). VEGF receptor 2 (VEGFR‐2; KDR) could also be identified in microvessels. High VEGF levels were present in homogenates from granulation tissue by enzyme‐linked immunosorbent assay (ELISA) and western blot experiments: low concentrations were found in areas of central necrosis and negligible amounts were present in normal skin. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) showed that only the splice variants VEGF121 and VEGF165 were expressed. In cultured fibroblasts, hypoxia or platelet‐derived growth factor (PDGF) raised VEGF production. The angiogenic peptide VEGF is present in all zones of chronic decubital ulcers. Its strong expression within the adjacent granulation tissue supports the view that there is no deficiency of VEGF. VEGF may be involved in the healing process of chronic skin lesions, but it seems that loss of another factor may be responsible for the poor healing response. Copyright © 2003 John Wiley & Sons, Ltd.
hnRNP B1 expression in benign and malignant lung disease
Authors: Snead DRJ , Perunovic B , Cullen N , Needham M , Dhillon DP , Satoh H , Kamma H
Published: April 2003

Evidence is accumulating to suggest that hnRNP B1 expression may be a useful tool in the early diagnosis of lung cancer. This study examined the immunohistochemical expression of hnRNP B1 in archived sections of resected lung cancers and compared the patterns of expression with those seen in similar archived sections of non‐neoplastic lung. Particular attention was paid to the expression of hnRNP B1 in the benign bronchial cells in both cases, to establish if overexpression of this protein in respiratory epithelial cells is specific for malignancy. Nineteen cases of different types of non‐small cell carcinoma were examined (eight squamous cell, six adenocarcinomas, two carcinosarcomas, two undifferentiated large cell carcinomas, and one mucoepidermoid carcinoma) and compared with sections from 16 open lung biopsies (three cases of cryptogenic fibrosing alveolitis, two cases of sarcoidosis, two cases of organizing pneumonia, and one case each of tuberculosis, extrinsic allergic alveolitis, non‐specific interstitial pneumonitis, pneumocystis pneumonia, aspergilloma, respiratory bronchiolitis–interstitial lung disease, mineral dust disease, Sjögren's syndrome and systemic sclerosis vascular variant). All the tumours showed positive staining, with the vast majority, 16/19 (84%), showing strong diffuse nuclear staining. The background cells of these cases showed positive staining in alveolar macrophages, lymph node germinal centres, bronchial mucous glands, and bronchial epithelial cells. No significant difference was seen in the percentage of positive bronchial epithelial cells in bronchi adjacent to the tumour compared with the resection margins. In the benign lung cases, positive bronchial epithelial cells were seen in a small percentage, 3/16 (18%), of cases, but the majority of cases showed no or very focal staining. The levels of expression between benign epithelial cells of malignant cases, compared with benign, showed a significant difference when the staining was assessed in percentage of positive nuclei (p = 0.001, Fisher's exact test). The results confirm that hnRNP B1 is widely expressed in a range of lung carcinomas; that expression is seen in benign bronchial epithelial cells and inflammatory cells; and that expression in background bronchial epithelial cells appears to be higher in malignant than in benign lung disease. It is feasible that this biomarker may be of use in the detection of early lung cancer, provided that levels of expression can be accurately quantified. Copyright © 2003 John Wiley & Sons, Ltd.