bluuebunny/crossref_metadata_2025 huggingface dataset:
Trends in extreme daily precipitation indices in India
Authors: Sen Roy Shouraseni , Balling Robert C.
Published: March 2004

We assembled daily precipitation records, initially for 3838 stations, throughout India and ultimately identified 129 stations with reasonably complete records over the period 1910 to 2000. From these daily records, we generated annual time series of seven different indices of extreme precipitation events, including total precipitation, largest 1, 5, and 30 day totals, and the number of daily events above the amount that marks the 90th, 95th, and 97.5th percentiles of all precipitation at each station. Of the 903 different time series (seven variables for 129 stations), 114 had a significant upward trend and 61 had a significant downward trend; overall, 61% of the time series showed an upward trend. The standard regression coefficients showing the strength and sign of the trend were highly correlated across the network. They generally showed increasing values in a contiguous region extending from the northwestern Himalayas in Kashmir through most of the Deccan Plateau in the south and decreasing values in the eastern part of the Gangetic Plain and parts of Uttaranchal. Our results are in general agreement with the prediction from numerical models for an increase in extreme precipitation events in India given the ongoing build‐up of greenhouse gases. Copyright © 2004 Royal Meteorological Society
On the use of relaxation parameters in hybrid smoothers
Authors: Yang Ulrike Meier
Published: March 2004

The use of relaxation parameters in hybrid smoothers within algebraic multigrid (AMG) is analysed both theoretically and practically. Relaxation parameters that are optimal under the assumptions of the theory are determined. The implementation of a procedure to automatically determine outer relaxation parameters for symmetric positive definite smoothers is described. Numerical results are presented, which show significant improvements over AMG with undamped hybrid smoothers. Copyright © 2004 John Wiley & Sons, Ltd.
Monotone multigrid methods based on element agglomeration coarsening away from the contact boundary for the Signorini's problem
Authors: Iontcheva Ana H. , Vassilevski Panayot S.
Published: March 2004

Two multilevel schemes for solving inequality constrained finite element second‐order elliptic problems, such as the Signorini's contact problem, are proposed and studied. The main ingredients of the schemes are that first they utilize element agglomeration coarsening away from the constraint set (boundary), which allows for easy construction of coarse level approximations that straightforwardly satisfy the fine‐grid constraints. Second important feature of the schemes is that they provide monotone reduction of the energy functional throughout the multilevel cycles. This is achieved by using monotone smoothers (such as the projected Gauss–Seidel method) and due to the fact that the recursive application of the two‐grid schemes is also monotone. The performance of the resulting methods is illustrated by numerical experiments on a model 2D Signorini's problem. Copyright 2004 © John Wiley & Sons, Ltd.
A multigrid approach to two‐dimensional phase unwrapping
Authors: Dardyk Gregory , Yavneh Irad
Published: March 2004

The two‐dimensional phase unwrapping problem is studied. Using the minimum Lp‐norm approach, we apply three different non‐linear multigrid algorithms for reconstructing surfaces from their ‘wrapped’ values—two classical approaches and a novel multilevel non‐linear method (MNM). The methods prove to be efficient even for difficult problems with noisy and discontinuous original images. The new method, MNM, exhibits the fastest and most robust convergence of the three, given an appropriate choice of a damping parameter. This parameter is determined automatically on very coarse grids at a small computational cost. Copyright 2004 John Wiley & Sons, Ltd.
Simulating sedimentation of liquid drops
Authors: Adekojo Waheed M. , Henschke Martin , Pfennig Andreas
Published: March 2004

This work was carried out to investigate the effect of fluid properties on the flow pattern and on the sedimentation velocity of an axisymmetric steady flow of a Newtonian fluid past a liquid drop in an unbounded region. The governing equations of motion were solved by the finite element method. The results show that the flow pattern of a liquid drop depends strongly both on the Reynolds number and on the ratio of the viscosity between the drop and the surrounding flowing fluids. The viscosity ratio in the range 0.02<μ*<50 has appreciable effect on the drag coefficient. Finally, a correlation for the sedimentation velocity is presented. Copyright © 2004 John Wiley & Sons, Ltd.
Consistent coupling of beam and shell models for thermo‐elastic analysis
Authors: Chavan K. S. , Wriggers P.
Published: March 2004

In this paper, the finite element formulation of a transition element for consistent coupling between shell and beam finite element models of thin‐walled beam‐like structures in thermo‐elastic problems is presented. Thin‐walled beam‐like structures modelled only with beam elements cannot be used to study local stress concentrations or to provide local mechanical or thermal boundary conditions. For this purpose, the structure has to be modelled using shell elements. However, computations using shell elements are a lot more expensive as compared to beam elements. The finite element model can be more efficient when the shell elements are used only in regions where the local effects are to be studied or local boundary conditions have to be provided. The remaining part of the structure can be modelled with beam elements. To couple these two models (i.e. shell and beam models) at transitional cross‐sections, transition elements are derived here for thermo‐elastic problems. The formulation encloses large displacement and rotational behaviour, which is important in case of thin‐walled beam‐like structures. Copyright © 2004 John Wiley & Sons, Ltd.
Mesh motion techniques for the ALE formulation in 3D large deformation problems
Authors: Farinatti Aymone José Luf́s
Published: March 2004

Efficient mesh motion techniques are a key issue to achieve satisfactory results in the arbitrary Lagrangian–Eulerian (ALE) finite element formulation when simulating large deformation problems such as metal‐forming. In the updated Lagrangian (UL) formulation, mesh and material movement are attached and an excessive mesh distortion usually appears. By uncoupling mesh movement from material movement, the ALE formulation can relocate the mesh to avoid distortion. To facilitate the calculation process, the ALE operator is split into two steps at each analysis time step: UL step (where deformation due to loading is calculated without convective terms) and Eulerian step (where mesh motion is applied). In this work, mesh motion is performed by new nodal relocation methods, developed for eight‐node hexahedral elements, which can move internal and boundary nodes, improving and concentrating the mesh in critical zones. After mesh motion, data is transferred from the UL mesh to the relocated mesh using an expansion of stresses in a Taylor's series. Two numerical applications are presented, comparing results of UL and ALE formulation with results found in the literature. Copyright © 2004 John Wiley & Sons, Ltd.
Meshfree implementation for the real‐space electronic‐structure calculation of crystalline solids
Authors: Jun Sukky
Published: March 2004

A meshfree formulation of the Schrödinger equation having periodic potential is presented. The conventional meshfree shape function is modified to express properly the periodicity of Bravais lattice. Then, it is applied to the electronic‐structure calculation of crystalline solids in real space. Numerical examples are the Kronig–Penney model potential and the empirical pseudopotentials of diamond and zinc‐blende semiconductors. Results prove that the meshfree method is a promising one to be used as a real‐space technique for the calculations of electronic structures. Copyright © 2004 John Wiley & Sons, Ltd.
Compliant rubber domains in a rigid polymer matrix: Shape and orientation factors related to cavitation and plastic dissipation
Authors: Fond C. , Schirrer R.
Published: March 2004

The hydrostatic stress in compliant rubber inclusions embedded in a rigid polymer matrix is evaluated for various shapes and orientations of the rubber domains and triaxialities of the remote stress tensor to determine the propensity of the inclusions to undergo cavitation. The first section analyzes the case of rubber particles of an ellipsoidal shape assuming linear elasticity of the matrix and small strains. It is shown that flat shapes, of which the long axis lies perpendicular to the direction of the maximum principal stress, are subjected to the highest levels of hydrostatic stress. The pressure induced by the deviatoric part of the remote stress tensor in the compliant rubber domains depends strongly on their shape and orientation, whereas the pressure induced by the hydrostatic part of the tensor is almost insensitive to the shape and orientation of the compliant domains. The second section examines the stress concentrations for elastoplasticity and plastic dissipation in the matrix. It is found that spherical inclusions ensure the best compromise between the early occurrence of plasticity and large amounts of plastic dissipation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1476–1486, 2004
Anomalous rheology in a nanostructured diblock copolymer/hydrocarbon system and its kinetic origin
Authors: Liu Zhizhong , Chattopadhyay Sruti , Shaw Montgomery T. , Hsiao Benjamin S.
Published: March 2004

Nanostructured squalane solutions (5–20 wt %) of a diblock copolymer, poly(styrene‐b‐hydrogenated isoprene), were prepared by a cosolvent‐casting method. The as‐cast solutions behaved as viscous liquids with terminal flow behavior at room temperature. Upon heating, the solutions gelled, and they did not return to their starting liquidlike state upon cooling. Small‐angle X‐ray scattering (SAXS) revealed a random array of spherical micelles in the as‐cast solutions, which were hypothesized to be in a nonequilibrium state. This abnormal solidification with increasing temperature was correlated with the formation of body‐centered‐cubic (BCC) structures. Isothermal SAXS and rheology measurements also indicated that the rate of formation of BCC structures in the as‐cast solutions increased with temperature. A diffusion‐controlled nucleation‐and‐growth mechanism was proposed for the ordering process in the as‐cast polystyrene‐b‐hydrogenated polyisoprene/squalane solutions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1496–1505, 2004
Brittle–ductile transition of polypropylene/ethylene–propylene–diene monomer blends induced by size, temperature, and time
Authors: Jiang Wei , Yu Donghong , An Lijia , Jiang Bingzheng
Published: March 2004

To study the brittle–ductile transition (BDT) of polypropylene (PP)/ethylene–propylene–diene monomer (EPDM) blends induced by size, temperature, and time, the toughness of the PP/EPDM blends was investigated over wide ranges of EPDM content, temperature, and strain rate. The toughness of the blends was determined from the tensile fracture energy of the side‐edge notched samples. The concept of interparticle distance (ID) was introduced into this study to probe the size effect on the BDT of PP/EPDM blends, whereas the effect of time corresponded to that of strain rate. The BDT induced by size, temperature, and time was observed in the fracture energy versus ID, temperature, and strain rate. The critical BDT temperatures for various EPDM contents at different initial strain rates were obtained from these transitions. The critical interparticle distance (IDc) increased nonlinearly with increasing temperature, and when the initial strain rate was lower, the IDc was larger. Moreover, the variation of the reciprocal of the initial strain rate with the reciprocal of temperature followed different straight lines for various EPDM contents. These straight lines were with the same slope. Furthermore, a diagram at critical BDT points in three dimensions (ID, T, and initial strain rate) was given for the PP/EPDM blends. The brittle and ductile zones are clearly shown in this diagram. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1433–1440, 2004
Phase behaviors of symmetric polymer blend systems
Authors: Chang Bong Ho , Bae Young Chan
Published: March 2004

The modified double‐lattice model is extended to polymer blend systems. We redefine Cγ as a new universal function of interaction energy to reduce the mathematical defects that originate from the truncation of higher order interaction energy terms. We correlate Cγ with Ryu et al.'s numerical results for symmetric polymer blends with various chain lengths (r1 = r2 = 8, 20, 50, or 100). In addition, oriented interactions between polymer segments are considered with respect to the secondary lattice concept. The proposed model shows a good agreement with the experimental data. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1532–1538, 2004
Multiphysical modeling and meshless simulation of electric‐sensitive hydrogels
Authors: Li Hua , Chen Jun , Lam K. Y.
Published: March 2004

According to a multiphase mixture theory, we have mathematically developed a multiphysical model with chemoelectromechanical coupling considerations, termed the multieffect‐coupling electric‐stimulus (MECe) model, to simulate the responsive behavior of electric‐sensitive hydrogels immersed in a bath solution under an externally applied electric field. For solutions of the MECe model consisting of coupled nonlinear partial differential governing equations, a meshless Hermite–Cloud method with a hierarchical iteration technique has been used for a one‐dimensional steady‐state analysis of a hydrogel strip. The computed results are compared with the experimental data, and there is very good agreement. Simulations within the domains of both hydrogels and surrounding solutions also present distributions of the ionic concentrations and electric potential as well as the hydrogel displacement. The effects of various physical parameters on the response behavior of electric‐stimulus responsive hydrogels are discussed in detail. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1514–1531, 2004
Simultaneous wide‐angle X‐ray diffraction and differential scanning calorimetry analysis of the melting and recrystallization behavior of polyethylene and isotactic polypropylene containing cyclopentane units in the main chain
Authors: Naga Naofumi
Published: March 2004

The melting and crystallization behavior of polyethylene and isotactic polypropylene containing 1,2‐ or 1,3‐disubstituted cyclopentane units in the main chain has been studied with simultaneous wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry. For the ethylene‐based copolymers, the position of a reflection peak in the WAXD patterns shifts to a low angle with the increasing acquired temperature. The temperature dependence on the axial length of the crystal lattice is more marked in the copolymers forming orthorhombic crystals (containing 1,2‐cyclopentane or 5.6 mol % 1,3‐cyclopentane units) than in those forming hexagonal crystals (containing 8.1 mol % 1,3‐cyclopentane units). For the isotactic propylene‐based copolymers, the position of the reflection peaks in the WAXD patterns is independent of the acquired temperature. The proportion of the γ form in the copolymer containing the 1,2‐cyclopentane units is higher than that in the copolymers containing the 1,3‐cyclopentane units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1457–1465, 2004
Physical properties of poly(ε‐caprolactone) layered silicate nanocomposites prepared by controlled grafting polymerization
Authors: Gorrasi Giuliana , Tortora Mariarosaria , Vittoria Vittoria , Pollet Eric , Alexandre Michael , Dubois Philippe
Published: March 2004

Poly(ε‐caprolactone) (PCL) chains grafted onto montmorillonite modified by a mixture of nonfunctional ammonium salts and ammonium‐bearing hydroxyl groups were prepared. The clay content was fixed to 3 wt %, whereas the hydroxyl functionality was 25, 50, 75, and 100%, obtaining an intercalated or exfoliated system. The transport properties of water and dichloromethane vapors and the mechanical properties were investigated. The mechanical and dynamic mechanical analyses showed improvement of the nanocomposite elastic modulus in a wide temperature range. Interestingly, for the higher hydroxyl contents (50, 75, and 100%), the decrease of modulus at higher temperature, due to the PCL crystalline melting, did not lead to the loss of mechanical consistence of the samples. Consequently, they revealed a measurable modulus up to 120 °C, a much higher temperature with respect to pure PCL. Water sorption was investigated in the entire activity range, and a lower sorption was observed on increasing the hydroxyl content, up to the sample with 100% hydroxyl content, which turned to be completely impermeable, even in liquid water. The sample with 75% hydroxyl content showed a threshold activity (a = 0.4) below which it was impermeable to water vapor. Also, the diffusion parameters decreased when the hydroxyl content increased, up to the 100% sample, which showed zero diffusion. The diffusion parameters of an organic vapor, dichloromethane, also exhibited a decreasing value on increasing the hydroxyl content in the nanocomposites. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1466–1475, 2004
Tachyon condensation for intersecting branes at small and large angles
Authors: Epple F. , Lüst D.
Published: March 2004

We review the worldsheet analysis for intersecting branes with focus on small and large angles. For small angles, we review the Yang‐Mills fluctuation analysis in [1] and find an additional family of massless modes. They are the components of a Goldstone scalar corresponding to the spontaneously broken U(2)‐gauge symmetry. For branes at large angles, we derive an effective tachyon field theory from BSFT results. We show how the gauge symmetry of this system implies a mass spectrum which is consistent with the worldsheet analysis.
Systems engineering aspects in theatre missile defense—design principles and a case study
Authors: Ben‐Asher Joseph Z.
Published: March 2004

Theatre missile defense systems are classified as systems‐of‐systems. System‐level design principles should therefore apply to this type of systems. These principles involve mainly balancing between independency and autonomy of the subsystems on the one hand, with strong incentives for collaboration on the other hand. A case study of a theatre missile defense boost‐phase interception system is studied in light of these principles. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 186–194, 2004
Minimizing the cost of availability of coverage from a constellation of satellites: Evaluation of optimization methods
Authors: Kelley Clifford , Dessouky Maged
Published: March 2004

Satellite systems to provide terrestrial surface coverage are currently optimized by independently optimizing parts of the system or by locally starting at a “baseline” configuration and making small changes. Even when using a “baseline,” the various components such as constellation configuration, satellite design, and acquisition have generally been optimized separately. A model was developed to minimize the life‐cycle cost of the system as a whole with the appropriate linkages between the major parts of the system in both cost and performance. The model consists of a cost model, and a performance model. The cost model includes the cost of purchasing and maintaining an inventory of satellites and launch vehicles, launch operations, and orbit operations. The performance model evaluates the availability over geographic grid averaging areas over a given period of time. The performance of local optimization techniques (Simplex and Complex) was evaluated against global optimization techniques (Simulated Annealing and Genetic Algorithms) for providing availability of coverage. The global optimization techniques performed much better with Genetic Algorithms performing slightly better than Simulated Annealing. The quality of the solutions found was benchmarked against a trade study and local optimization methods, and our proposed global systems approach provided significant cost savings over the existing techniques. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 113–122, 2004
System‐level application of the evolutionary product development process to manufactured goods
Authors: McDevitt Carol Ann , Cahill Eric C , Stambaugh Craig
Published: March 2004

Current literature on software product development suggests that it is possible to develop the software architecture alongside the software itself using an evolutionary product development process. That is, engineers can delay finalization of product architecture until well along in the product development process. If there is a financial incentive to delay “freezing” the architecture until the latter stages of product development, could this process also be used for manufactured goods? This paper provides some examples of delayed architectural decisions, discusses when there might be financial incentives, and then shows some interesting new practices which might facilitate this process. It then comments on the applicability of this evolutionary approach to the development of the product architecture of manufactured goods, and concludes that manufactured goods can potentially realize the gains derived from an evolutionary approach to architectural design. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 144–152, 2004
The ISRE method for analyzing system requirements with virtual prototypes
Authors: Sutcliffe Alistair , Gault Brian
Published: March 2004

Virtual prototyping is a useful approach for refining requirements and testing designs in systems engineering; however, use of virtual reality technology can cause usability problems which can be interpreted as “false positive” requirements errors. The ISRE method guides the analysis of problems encountered during the testing of virtual prototypes and helps assign causes to either genuine design defects or usability issues with Virtual Reality (VR) technology. The method consists of techniques for walkthrough testing, testing with users, causal analysis of observed problems, and design of scenario‐based analysis sessions. A checklist of requirements questions is given, with guidance on scenario‐based testing of virtual prototypes and advice on configuring VR technology to obtain the best results from virtual prototyping sessions. The method is described and its use illustrated with a case study of validating requirements for an aircraft maintenance application. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 123–143, 2004
Value‐centered R&D organizations: Ten principles for characterizing, assessing, and managing value
Authors: Rouse William B. , Boff Kenneth R.
Published: March 2004

The management of R&D organizations has received considerable attention in terms of the nature of the flow from research to development to deployed technology, as well as planning and managing this flow. R&D strategies, innovation funnels, and multistage decision processes, to name just a few constructs, have been articulated and elaborated. This article builds on this foundation to consider the nature of the value created by this process. An options‐based approach is advocated for economic valuation of the products of R&D. Adoption and implementation of this approach is outlined in terms of ten principles for characterizing, assessing, and managing value. © 2004 Wiley Periodicals, Inc.† Syst Eng 7: 167–185, 2004
Management of international strategic business cooperation: Situational conditions, performance criteria, and success factors
Authors: Holtbrügge Dirk
Published: March 2004

In recent years, international strategic business cooperation has attracted great attention in both
international management theory and practice. Several prominent examples demonstrate that interfirm alliances can
no longer be viewed as second‐best solutions but must be recognized as efficient forms of
internationalization.

In this article, the specific management problems of international strategic business cooperation are analyzed
and a systematic approach for their solution is presented. After outlining three examples that represent three
different forms of international strategic business cooperation, a conceptual framework is developed that
integrates three different perspectives: situational conditions, management instruments, and performance
criteria. In the main part of the article, five success factors of international strategic business cooperation
(partner selection, cooperation agreement, management structure, acculturation process, and knowledge
management) are discussed. The article ends with a short summary and implications for further research.
© 2004 Wiley Periodicals, Inc.
Business goals in market versus transition economies: An exploratory comparison of Hungarian and U.S. MBA students
Authors: Danis Wade M. , Shipilov Andrew V.
Published: March 2004

Developed market economies and transition economies are characterized by radically different institutional,
economic, and cultural environments, which we expected would produce differences in business goals among MBA
students. We measured differences between 103 Hungarian and 454 U.S. part‐time MBAs and found that U.S.
respondents placed more importance on growth of the business, short‐term profits, staying within the laws,
and honor, face, and reputation. Hungarians placed more emphasis on game and gaming spirit, and family values.
Although the results showed significant differences on some business goals, they were not as great as the
literature would suggest, indicating that some convergence has occurred since transition began. © 2004 Wiley
Periodicals, Inc.
Doing business in Poland: What U.S. managers need to know
Authors: DeDee J. Kim , Frederickson Paul
Published: March 2004

Poland has been and continues to be the leader of the transition economies of Eastern Europe. This study
provides an in‐depth look at the ongoing economic, legal, and administrative policies of the Polish
government in laying the ground‐work for a free‐market society. With the smaller business in mind,
we first examine how the government of Poland moved decisively to lay the cornerstone for a
private‐sector
economy. Next, we demonstrate how Poland redirected its political and legal processes for long‐term
global
business. Finally, we describe what the U.S. government is doing to help Poland become a better trading partner
and what this means to interested American firms. While there are many deep‐seated positive changes
throughout Poland as it becomes a more significant global business player, there also are many challenges that
must be understood by interested U.S. businesses if their investments in Poland are to be successful. ©
2004
Wiley Periodicals, Inc.
The management of exchange‐rate risk: A case from the manufacturing industry
Authors: Dhanani Alpa
Published: March 2004

This article looks into the management of exchange rate risk at a U.K.‐listed company. The focus is
particularly on the firm's operating exchange risk, for which it uses a synthesis of three different risk
management approaches. These include the use of long‐term financial hedging instruments, operational
adjustments based on real options theory, and the currency denomination of debt. Practice at the case company is
unique, in that the former approach has been considered inappropriate by the theoretical literature and the latter
is seldom used to manage firms' real cash flow exposures. In general, it has important implications for
multinationals, especially with reference to the use of operational adjustments and the currency denomination of
debt. © 2004 Wiley Periodicals, Inc.
The pleasures, perils, and possibilities of undertaking international business research
Authors: Amine Lyn S.
Published: March 2004

Brian Toyne, Zaida L. Martínez, & Richard A. Menger (Eds.). 2001. International
Business Scholarship: Mastering Intellectual, Institutional, and Research Challenges. Westport, CT: Quorum
Books. ISBN: 1‐56720‐351‐5.

Masaaki (Mike) Kotabe & Preet S. Aulakh (Eds.). 2002. Emerging Issues in
International Business Research. Northampton, MA: Edward Elgar. ISBN:
1‐84064‐836‐8.
Entrepreneurial management revisited
Authors: Khan Wasif M.
Published: March 2004

Dan Steinbock. 2001. The Nokia Revolution: The Story of an Extraordinary Company that Transformed an
Industry, New York: AMACOM. ISBN: 0‐8144‐0636‐X.

Saul Rubenstein & Thomas A. Kochan. 2001. Learning from Saturn: Possibilities for Corporate
Governance and Employee Relations. Ithaca, NY: Cornell University Press. ISBN:
0‐8014‐3873‐X.

Jason Goodwin. 2001. Otis: Giving Rise to the Modern City. Chicago: Ivan S. Dee. ISBN:
1‐56663‐385‐0.
Effects of triethylene tetraamine on telomerase activity and proliferation in HeLa cells
Authors: Yin Fei , Liu Jianhui , Peng Xiaojun
Published: March 2004

Telomerase, which is required to maintain telomeres, has attracted considerable attention as a target for anticancer therapy. In this study, we investigated the inhibition of HeLa cell telomerase activity and cell cycle progression by triethylene tetraamine (TETA), using a modified telomeric repeat amplification protocol (TRAP) assay, and flow cytometry. TETA inhibited telomerase activity in HeLa cell extracts, with an IC50of about 7.8 μM. Coupled with this inhibition, TETA also increased the proportion of cells in the G1phase of the cell cycle in a dose‐dependent manner. These findings demonstrate that TETA is a potent inhibitor of telomerase in micromolar concentrations, and inhibits the proliferation of HeLa cells by arresting them in G1.
Cardiac chimerism in recipients of peripheral‐blood and bone marrow stem cells
Authors: Bayes‐Genis Antoni , Muñiz‐Diaz Eduardo , Catasus Lluis , Arilla Marina , Rodriguez Carmen , Sierra Jordi , Madoz Pedro J. , Cinca Juan
Published: March 2004

Multipotent progenitor cells have the ability to differentiate into most somatic cell types, including cardiac myocytes. We sought to investigate cardiac chimerism after peripheral‐blood and bone marrow stem cell transplantation. Between 10 and 17 highly polymorphic short tandem repeat (STR) markers were assayed in DNA obtained from donors’ peripheral blood, recipients’ peripheral blood before transplantation, and the recipient's heart in every patient. Gender and non‐gender STR donor alleles were identified in the recipient heart in three patients. Using a highly sensitive PCR assay to determine donor and recipient genotypes, we confirmed the existence of cardiac chimerism in recipients of peripheral‐blood and bone marrow stem cells.
Necessity and redundancy of guidepost cells in the embryonic Drosophila CNS
Authors: Whitington Paul M. , Quilkey Carol , Sink Helen
Published: March 2004

Guidepost cells are specific cellular cues in the embryonic environment utilized by axonal growth cones in pathfinding decisions. In the embryonic Drosophila CNS the RP motor axons make stereotypic pathways choices involving distinct cellular contacts: (i) extension across the midline via contact with the axon and cell body of the homologous contralateral RP motoneuron, (ii) extension down the contralateral longitudinal connective (CLC) through contact with connective axons and longitudinal glia, and (iii) growth into the intersegmental nerve (ISN) through contact with ISN axons and the segmental boundary glial cell (SBC). We have now ablated putative guidepost cells in each of the CNS pathway subsections and uncovered their impact on subsequent RP motor axon pathfinding. Removal of the longitudinal glia or the SBC did not adversely affect pathfinding. This suggests that the motor axons either utilized the alternative axonal substrates, or could still make filopodial contact with the next pathway section's cues. In contrast, RP motor axons did require contact with the axon and soma of their contralateral RP homologue. Absence of this neuronal substrate frequently impeded RP axon outgrowth, suggesting that the next cues were beyond filopodial reach. Together these are the first direct ablations of putative guidepost cells in the CNS of this model system, and have uncovered both pathfinding robustness and susceptibility by RP axons in the absence of specific contacts.
Over‐expression of bHLH genes facilitate neural formation of mouse embryonic stem (ES) cells in vitro
Authors: Kanda Seiji , Tamada Yasuko , Yoshidome Atsuko , Hayashi Itoko , Nishiyama Toshimasa
Published: March 2004

Mouse embryonic stem (ES) cells are useful tools for investigating differentiation into neurons and glial cells in vitro. In order to induce ES cells to differentiate into neural cells, many researchers have investigated the efficiency of induction. Embryoid body (EB) formation and retinoic acid are potent differentiation inducers known to be a trigger at the early stage of development. Basic helix‐loop‐helix (bHLH) is one of the important transcription factors, which is essential for premature neural formation. In NeuroD2 and Mash1‐transfected cells, neural formation was observed at day 6 after the plating of embryoid bodies in culture. Nestin was detected in NeuroD2‐ and Mash1‐transfected cells at day 10, and strong signal was detected in Mash1 transfectants by RT‐PCR analysis. Map2 and Nurr1 were also detected strongly at the early stage in transfected cells compared with the wild type control, especially in the Mash1 transfectant. In immunocytochemical analysis, Tuj1‐positive neurons were detected at high frequency in Mash1 transfectants and some cells were stained by tyrosine hydrogenase (TH), a marker of dopaminergic neurons. These results demonstrate that bHLH has a potential activity at an early stage for ES cells and can induce effective and rapid neural differentiation in vitro.
Assessing joint maintenance shops in the Taiwanese Army using data envelopment analysis
Authors: Sun Shinn
Published: March 2004

This paper proposes an alternative data envelopment analysis (DEA) method for assessing the performance of joint maintenance shops (JMSs) in the Taiwanese Army over two 6‐month periods in 2000. It further examines the possibility of using DEA over time as a basis for continuous improvement. To help productivity improvements, the DEA results for the first time period were implemented at the five selected JMSs located in Taipei, Taoyuan, Taichung, Chaiyi, and Kaoshiung. The findings show that most of previously inefficient JMSs, on average, have become relative more efficient through DEA recommendation remedial actions. Three JMSs increased their technical and pure technical efficiencies; and one JMS increased its scale efficiency. Few JMSs were operating at increasing returns to scale, indicating a potential to expand. As such, it can be a valuable benchmarking tool for the JMS managers and assist in efficiently using scare resources to produce productivity. Finally, the Army has accepted DEA as a performance measurement tool for JMSs.
Contrasting effects of fire on populations of two small rodent species in fragments of Atlantic Forest in Brazil
Authors: de Souza Lima Figueiredo Marcos , Fernandez Fernando Antonio dos Santos
Published: March 2004

Habitat fragmentation causes a sharp increase in the forested area affected by edge effects (Murcia 1995). Compared with the core of the forest, edges present higher litterfall rates, air and soil humidity reduction, higher temperature and increased wind incidence (Bierregaard et al. 1992, Didham & Lawton 1999, Laurance et al. 1998, Matlack 1993). These features of edges may increase the probability of fire occurrence, especially if the surrounding vegetation is composed of grasses (D'Antonio & Vitousek 1992, Freifelder et al. 1998). After a fire, the damaged edge will grow substantial amounts of herbaceous vegetation, extending the inflammable area into the forest, and thereby creating a positive feedback system of fire susceptibility and intensity (Cochrane & Schulze 1999, Cochrane et al. 1999). Fires may affect the structure and composition of the vegetation (Cochrane & Schulze 1999, Didham & Lawton 1999, Sanaiotti & Magnusson 1995), favouring, in the long-term, the dominance of the community by species characteristic of disturbed habitats and making the habitat unsuitable to primary forest species (Malcolm 1994, Possingham et al. 1994). Unfortunately, there are few studies on the effects of fires on neotropical small-mammal populations (Borchert & Hansen 1983, Ojeda 1989, Vieira & Marinho-Filho 1998). The objective of this study was to analyse the influence of a fire on populations of two rodent species, Akodon cursor (Winge) and Oecomys concolor (Wagner) in two fragments of Atlantic Forest in Brazil.
Competition among visitors to extrafloral nectaries as a source of ecological costs of an indirect defence
Authors: Heil Martin , Hilpert Andrea , Krüger Ralf , Linsenmair K. Eduard
Published: March 2004

Extrafloral nectar is an indirect, generally ant-mediated, defence mechanism that is particularly common in tropical plants. This study focuses on interactions among different groups of arthropods visiting extrafloral nectaries of the South-East Asian myrmecophilic plant, Macaranga tanarius. The diurnal activity patterns of arthropods on nectaries were recorded on two occasions, each plant being used once in an untreated state and once after chemical induction of extrafloral nectar flow. Ants, widely regarded as the most important consumers of extrafloral nectar, made up only 60% of all nectary-visiting arthropods. Striking negative relations became obvious between ants and ‘non-ants’, among which two (morpho)species of fly (Grammicomya sp. and Mimegralla sp., both Micropezidae) were most important. On most leaves, either ants or ‘non-ants’, but not both groups, were present at one time. Behavioural observations revealed that many flies actively excluded other arthropods, including ants, from the nectaries or leaves. However, the flies had no detectable defensive effect against herbivores. The presence of these ‘thieves’ of extrafloral nectar therefore can cause ecological costs in terms of reduced presence of ants that consume extrafloral nectar and defend plants.
Structure and inferred dynamics of a large grove of Microberlinia bisulcata trees in central African rain forest: the possible role of periods of multiple disturbance events
Authors: Newbery D. M. , Burgt X. M. van der , Newbery D. M.
Published: March 2004

A 272-ha grove of dominant Microberlinia bisulcata (Caesalpinioideae) adult trees ≥50 cm stem diameter was mapped in its entirety in the southern part of Korup National Park, Cameroon. The approach used an earlier-established 82.5-ha permanent plot with a new surrounding 50-m grid of transect lines. Tree diameters were available from the plot but trees on the grid were recorded as being ≥50 cm. The grove consisted of 1028 trees in 2000. Other species occurred within the grove, including the associated subdominants Tetraberlinia bifoliolata and T. korupensis. Microberlinia bisulcata becomes adult at a stem diameter of c. 50 cm and at an estimated age of 50 y. Three oval-shaped subgroves with dimensions c. 850 m×1350 m (90 ha) were defined. For two of them (within the plot) tree diameters were available. Subgroves differed in their scales and intensities of spatial tree patterns, and in their size frequency distributions, these suggesting differing past dynamics. The modal scale of clumping was 40–50 m. Seed dispersal by pod ejection (to c. 50 m) was evident from the semi-circles of trees at the grove's edge and from the many internal circles (100–200 m diameter). The grove has the capacity, therefore, to increase at c. 100 m per century. To form its present extent and structure, it is inferred that it expanded and infilled from a possibly smaller area of lower adult-tree density. This possibly happened in three waves of recruitment, each one determined by a period of several intense disturbances. Climate records for Africa show that 1740–50 and 1820–30 were periods of drought, and that 1870–1895 was also regionally very dry. Canopy openings allow the light-demanding and fast-growing ectomycorrhizal M. bisulcata to establish, but successive releases are thought to be required to achieve effective recruitment. Nevertheless, in the last 50 y there were no major events and recruitment in the grove was very poor. This present study leads to a new hypothesis of the role of periods of multiple extreme events being the driving factor for the population dynamics of many large African tree species such as M. bisulcata.
Seasonal patterns of fine-root productivity and turnover in a tropical savanna of northern Australia
Authors: Chen Xiaoyong , Eamus Derek , Hutley Lindsay B.
Published: March 2004

Fine roots and their turnover represent a dynamic aspect of below-ground biomass (BGB) and nutrient capital in forest ecosystems, and account for a significant fraction of net primary productivity (NPP) (Cuevas 1995, Vogt et al. 1990). On a weight basis, coarse roots contribute more to total ecosystem biomass than fine roots, but they account for only a small portion of annual root production (Eamus et al. 2002). Despite the fact that fine roots may compose less than 2% of total ecosystem biomass, they may contribute up to 40% of total ecosystem production (Vogt et al. 1990). Therefore, estimates of root production, like estimates of root biomass, should differentiate between coarse- and fine-root production.
Preferences of fig wasps and fruit bats for figs of functionally dioecious Ficus pungens
Authors: Dumont Elizabeth R. , Dumont Elizabeth R. , Dumont Elizabeth R.
Published: March 2004

Figs (Ficus species) are an important resource for a diverse array of organisms in most tropical forests (Janzen 1979 but see Gautier-Hion & Michaloud 1989). The inflorescence of Ficus, hereafter referred to as the ‘fig’, is an enclosed receptacle lined with unisexual flowers. The flowers of Ficus species are pollinated by wasps that feed on galled fig ovules as larvae and that lay eggs in fig flowers as adults (Weiblen 2002). Ripe figs are consumed by vertebrate frugivores, which are the primary dispersers of fig seeds (Shanahan et al. 2001). The interaction between figs, pollinators and frugivores introduces the potential for conflict between the roles of raising fig wasps and dispersing seeds. Specifically, the pollination mutualism could be compromised if frugivores consumed figs containing pollinator larvae. This conflict is resolved in very different ways according to the breeding system of the fig.
Understorey fern responses to post-hurricane fertilization and debris removal in a Puerto Rican rain forest
Authors: Halleck Leslie Finical , Sharpe Joanne M. , Zou Xiaoming Zou
Published: March 2004

Controls over net primary productivity are the subject of a long-term experiment within a lowland subtropical wet forest in the Luquillo mountains of Puerto Rico. Responses of the fern community to fertilization and debris-removal treatments and to monitoring activities were assessed 6 y after the experiment began in October 1989, just after the passage of Hurricane Hugo. Negative fern responses to fertilization included a qualitative change in species composition and a 13-fold reduction in density compared with controls. Plants were smaller and spore production rates were lower. Debris removal reduced the number of species and increased the proportion of terrestrial species. Density of Nephrolepis rivularis individuals in debris-removal plots was only 5% that of control levels while abundance of Thelypteris deltoidea nearly doubled. Buffer-zone fern density was 36% greater than and per cent of leaves damaged was half that of the monitored zones. The magnitude of the responses of ferns to experimental treatments and to monitoring effects suggest that they may be good early indicators of change in a tropical forest.
Photosynthetic characteristics in relation to leaf traits in eight co-existing pioneer tree species in Central Sulawesi, Indonesia
Authors: Hölscher Dirk , Leuschner C. , Bohman K. , Juhrbandt J. , Tjitrosemito S.
Published: March 2004

Tropical pioneer tree species are considered as a functional group characterized by a suite of ecological characteristics such as high light demand and high photosynthetic capacities. This study compared the photosynthetic characteristics of eight co-existing pioneer tree species in 3–4-y-old and about 6-m-tall secondary forest stands in Sulawesi, Indonesia. Its objectives were (1) to determine the range and interspecific variation in six photosynthetic parameters, and (2) to identify morphological and chemical leaf traits that can predict light-saturated net photosynthetic rates (on a leaf area or leaf mass basis, Amax-area or Amax-mass). Species averages of Amax-area in sun leaves ranged between 14.2 and 20.3 μmol m−2 s−1 (mean 17.5) which is high compared with literature data. Among the co-existing species, average leaf size (56–896 cm2) differed by a factor of 16, specific leaf area (SLA, 10.7–21.4 m2 kg−1) and leaf nitrogen content (19.6–33.9 g kg−1) twofold. At the species level, Amax-area was not correlated with leaf N content but decreased significantly with leaf size. Amax-mass showed a higher interspecific variation than Amax-area, and was positively correlated with SLA and leaf N content (slope: 13.4 nmol CO2 g N−1 s−1). Both, Amax-area and Amax-mass were more closely related to leaf morphological attributes than to leaf N. We conclude that the tropical pioneer tree species studied do not form a homogeneous functional group in terms of photosynthetic performance. Rather, a considerable variation in leaf morphology and nitrogen content exists, which also shows up in a substantial variation in Amax-mass and, to a lesser extent, in Amax-area.
Effects of soil water regime and grazing on vegetation diversity and production in a hyperseasonal savanna in the Apure Llanos, Venezuela
Authors: Sarmiento Guillermo , Pinillos Marcela , Silva Marta Pereira da , Acevedo Dimas
Published: March 2004

Soil water content and above-ground biomass accumulation, above 10 cm high, were measured monthly in a flooded savanna ecosystem under grazing pressure and under cattle exclusion, during two growth cycles. Near-to-the-ground and below-ground biomass were measured three times during this period. Besides, composition, species richness and diversity were obtained through a floristic inventory. Despite a relatively high floristic richness and diversity, Panicum laxum is the dominant species throughout the study area, while three other perennial grasses, Paspalum chaffanjonii, Leersia hexandra and Axonopus purpusii, also reach high values of cover and biomass. Each of them reacts specifically to flooding, drought and grazing conditions. This ecosystem shows a strongly seasonal behaviour, with primary production, mortality and decomposition sharply timed by soil relative water content. Both drought and water excess seem to limit plant production, even more during wet years when the savanna might remain flooded for up to 4 mo. Some structural and functional differences between the grazed and the protected systems are demonstrated, but under the actual, relatively low stocking rate, the grazed savanna produces as much forage as the ungrazed one.
2003 Erasmus Lecture  Sex and reproduction: ready for divorce?
Authors: DJERASSI CARL
Published: March 2004

The effective separation of sex (‘in bed’) and fertilization (‘under the microscope’) has already been practised successfully for the past 25 years by well over one million people – virtually all of them suffering from infertility problems. But why, where and when will fertile people resort to assisted reproductive techniques to become parents? And why are the prospects for fundamentally new methods of birth control so dim?