bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential of Webservices to Enable Smart Business Networks
Authors: van Hillegersberg Jos , Boeke Ruurd , van den Heuvel Willem-Jan
Published: November 2004

Webservices (WSs) are believed to be among the key technologies to enable the transformation of current static supply chains into dynamic virtual networks of enterprises. Others have said that these technologies are not yet ready for large-scale applications to supply chains and propose ‘traditional’ cross-enterprise integration methods. However, there is currently little research available that objectively evaluates the usefulness of WSs to enable smart business networks. In this study, this question is addressed through developing a typical scenario in which we transform a static supply chain into a ‘loosely coupled’ business network. We implement the scenario using state-of-the-art ‘enterprise application integration’ and WSs orchestration technology. The comparison of these alternative approaches reveals that WSs technology has some clear advantages above enterprise integration technology currently in use. However, there are also some limitations and research issues which are presented as a future research agenda for WSs technology.
Cryptic false spider mites: a new genus, Austrolinus, and a review of the family Linotetranidae (Acari : Prostigmata : Tetranychoidea)
Authors: Beard Jennifer J. , Walter David Evans
Published: November 2004

The Linotetranidae (Acari : Tetranychoidea) is a poorly known group of cryptic false spider mites associated with grasses and sedges. We review the family at the world level, provide the first phylogenetic analysis of the family, and describe the first Australian representatives: Austrolinus, gen. nov. and two new species: A.��arenulus and A. kinnearae. Linotetranidae is redefined, and keys are provided for the families of the Tetranychoidea, and for all described genera and species of Linotetranidae.
Groups of diverse problem solvers can outperform groups of high-ability problem solvers
Authors: Hong Lu , Page Scott E.
Published: November 2004

We introduce a general framework for modeling functionally diverse problem-solving agents. In this framework, problem-solving agents possess representations of problems and algorithms that they use to locate solutions. We use this framework to establish a result relevant to group composition. We find that when selecting a problem-solving team from a diverse population of intelligent agents, a team of randomly selected agents outperforms a team comprised of the best-performing agents. This result relies on the intuition that, as the initial pool of problem solvers becomes large, the best-performing agents necessarily become similar in the space of problem solvers. Their relatively greater ability is more than offset by their lack of problem-solving diversity.
Induction of antiviral immunity requires Toll-like receptor signaling in both stromal and dendritic cell compartments
Authors: Sato Ayuko , Iwasaki Akiko
Published: November 2004

Pattern recognition by Toll-like receptors (TLRs) is known to be important for the induction of dendritic cell (DC) maturation. DCs, in turn, are critically important in the initiation of T cell responses. However, most viruses do not infect DCs. This recognition system poses a biological problem in ensuring that most viral infections be detected by pattern recognition receptors. Furthermore, it is unknown what, if any, is the contribution of TLRs expressed by cells that are infected by a virus, versus TLRs expressed by DCs, in the initiation of antiviral adaptive immunity. Here we address these issues using a physiologically relevant model of mucosal infection with herpes simplex virus type 2. We demonstrate that innate immune recognition of viral infection occurs in two distinct stages, one at the level of the infected epithelial cells and the other at the level of the noninfected DCs. Importantly, both TLR-mediated recognition events are required for the induction of effector T cells. Our results demonstrate that virally infected tissues instruct DCs to initiate the appropriate class of effector T cell responses and reveal the critical importance of the stromal cells in detecting infectious agents through their own pattern recognition receptors.
Guiding neuronal development with
in situ
microfabrication
Authors: Kaehr Bryan , Allen Richard , Javier David J. , Currie John , Shear Jason B.
Published: November 2004

We report the ability to modify microscopic 3D topographies within dissociated cultures, providing a means to alter the development of neurons as they extend neurites and establish interconnections. In this approach, multiphoton excitation is used to focally excite noncytotoxic photosensitizers that promote protein crosslinking, such as BSA, into matrices having feature sizes ≥250 nm. Barriers, growth lanes, and pinning structures comprised of crosslinked proteins are fabricated under conditions that do not compromise the viability of neurons both on short time scales and over periods of days. In addition, the ability to fabricate functional microstructures from crosslinked avidin enables submicrometer localization of controllable quantities of biotinylated ligands, such as indicators and biological effectors. Feasibility is demonstrated for using
in situ
microfabrication to guide the contact position of cortical neurons with micrometer accuracy, opening the possibility for engineering well defined sets of synaptic interactions.
Proteins of purified Epstein-Barr virus
Authors: Johannsen Eric , Luftig Micah , Chase Michael R. , Weicksel Steve , Cahir-McFarland Ellen , Illanes Diego , Sarracino David , Kieff Elliott
Published: November 2004

Mature Epstein-Barr virus (EBV) was purified from the culture medium of infected lymphocytes made functionally conditional for Zta activation of lytic replication by an in-frame fusion with a mutant estrogen receptor. Proteins in purified virus preparations were separated by gradient gel electrophoresis and trypsin-digested; peptides were then analyzed by tandem hydrophobic chromatography, tandem MS sequencing, and MS scans. Potential peptides were matched with EBV and human gene ORFs. Mature EBV was mostly composed of homologues of proteins previously found in a herpes virion. However, EBV homologues to herpes simplex virus capsid-associated or tegument components UL7 (BBRF2), UL14 (BGLF3), and EBV BFRF1 were not significantly detected. Instead, probable tegument components included the EBV and γ-herpesvirus-encoded BLRF2, BRRF2, BDLF2 and BKRF4 proteins. Actin was also a major tegument protein, and cofilin, tubulin, heat shock protein 90, and heat shock protein 70 were substantial components. EBV envelope glycoprotein gp350 was highly abundant, followed by glycoprotein gH, intact and furin-cleaved gB, gM, gp42, gL, gp78, gp150, and gN. BILF1 (gp64) and proteins associated with latent EBV infection were not detected in virions.
Interacting models of cooperative gene regulation
Authors: Das Debopriya , Banerjee Nilanjana , Zhang Michael Q.
Published: November 2004

Cooperativity between transcription factors is critical to gene regulation. Current computational methods do not take adequate account of this salient aspect. To address this issue, we present a computational method based on multivariate adaptive regression splines to correlate the occurrences of transcription factor binding motifs in the promoter DNA and their interactions to the logarithm of the ratio of gene expression levels. This allows us to discover both the individual motifs and synergistic pairs of motifs that are most likely to be functional, and enumerate their relative contributions at any arbitrary time point for which mRNA expression data are available. We present results of simulations and focus specifically on the yeast cell-cycle data. Inclusion of synergistic interactions can increase the prediction accuracy over linear regression to as much as 1.5- to 3.5-fold. Significant motifs and combinations of motifs are appropriately predicted at each stage of the cell cycle. We believe our multivariate adaptive regression splines-based approach will become more significant when applied to higher eukaryotes, especially mammals, where cooperative control of gene regulation is absolutely essential.
Reversible oxidation and inactivation of the tumor suppressor PTEN in cells stimulated with peptide growth factors
Authors: Kwon Jaeyul , Lee Seung-Rock , Yang Kap-Seok , Ahn Younghee , Kim Yeun Ju , Stadtman Earl R. , Rhee Sue Goo
Published: November 2004

Stimulation of cells with various peptide growth factors induces the production of phosphatidylinositol 3,4,5-trisphosphate (PIP
3
) through activation of phosphatidylinositol 3-kinase. The action of this enzyme is reversed by that of the tumor suppressor PTEN. With the use of cells overexpressing NADPH oxidase 1 or peroxiredoxin II, we have now shown that H
2
O
2
produced in response to stimulation of cells with epidermal growth factor or platelet-derived growth factor potentiates PIP
3
generation and activation of the protein kinase Akt induced by these growth factors. We also show that a small fraction of PTEN molecules is transiently inactivated as a result of oxidation of the essential cysteine residue of this phosphatase in various cell types stimulated with epidermal growth factor, platelet-derived growth factor, or insulin. These results suggest that the activation of phosphatidylinositol 3-kinase by growth factors might not be sufficient to induce the accumulation of PIP
3
because of the opposing activity of PTEN and that the concomitant local inactivation of PTEN by H
2
O
2
might be needed to increase the concentration of PIP
3
sufficiently to trigger downstream signaling events. Furthermore, together with previous observations, our data indicate that peroxiredoxin likely participates in PIP
3
signaling by modulating the local concentration of H
2
O
2
.
Circulating cytokine profile in anti‐neutrophilic cytoplasmatic autoantibody‐associated vasculitis: prediction of outcome?
Authors: Ohlsson Sophie , Wieslander Jörgen , Segelmark Mårten
Published: November 2004

AIMS: The anti‐neutrophilic cytoplasmatic autoantibody‐associated vasculitides (AASV) are diseases of relapsing‐remitting inflammation. Here we explore the cytokine profile in different phases of disease, looking for pathogenic clues of possible prognostic value.

Results: Interleukin (IL)‐6, IL‐8 and IL‐10 were significantly elevated in plasma. Patients in the stable phase who subsequently developed adverse events had higher IL‐8 values. Patients in the stable phase who relapsed within 3 months had lower IL‐10 values and higher IL‐6 levels.

Conclusions: Patients with AASV have raised circulating cytokine levels compared with healthy controls, even during remission. Raised IL‐8 seems associated with poor prognosis. Lower levels of IL‐10 and higher levels of IL‐6 herald a greater risk of relapse. Patients with systemic vasculitis in clinical remission have persistent disease activity, kept under control by inhibitory cytokines.
The limited immunomodulatory effects of escharectomy on the kinetics of endotoxin, cytokines, and adhesion molecules in major burns
Authors: Han Tae-Hyung , Lee Soo-Yeon , Kwon Jung-Eun , Kwak In-Suk , Kim Kwang-Min
Published: November 2004

ESCHARECTOMY has been shown to improve the survival rates and the outcomes in burns. This observational study was conducted to assess the role of escharectomy on the inflammatory mediators in major burns. Seventeen ASA physical status II or status III adult surviving major burn patients were recruited. When the escharectomy was scheduled, a series of blood samples was obtained at −3 and −1 days preoperation, and +1 and +3 postoperation. The changing levels of endotoxin, cytokines, and adhesion molecules were measured with a quantitative sandwich immunoassay. Extensive escharectomy did not appear to have any significant impact on the levels of tumor necrosis factor alpha, interleukin‐10, soluble intracellular adhesion molecule‐1 and soluble vascular adhesion molecule‐1. Meanwhile, endotoxin and E‐selectin were significantly decreased after escharectomy. Escharectomy appeared to have a limited immunomodulatory effect on the inflammatory mediators in systemic inflammatory responses induced by major burns. This is probably related to the timing and extent of surgery, and the complex nature of burn‐related inflammation.
Polo‐like Kinases and Chk2 at the Interface of DNA Damage Checkpoint Pathways and Mitotic Regulation
Authors: Tsvetkov Lyuben
Published: November 2004

The cell cycle controls processes of DNA replication and segregation of replicated DNA into two daughter cells. These processes are coordinated by multiple signaling pathways, which employ many protein kinases. The members of the family of Polo‐like protein kinases are among these key cell cycle regulators. In response to DNA damage and inhibited DNA replication, DNA structure checkpoints delay cell cycle progression to provide cells with time for repair of damaged DNA and protect it from more severe damage. These effects are achieved by affecting key players of the basic cell cycle regulation of the cells with damaged DNA. This review is focused on the interplay between Chk2, a bona fide checkpoint protein kinase, and Polo‐like kinases. IUBMB Life, 56: 449‐456, 2004
Phosphatidylinositol Transfer Proteins: Emerging Roles in Cell Proliferation, Cell Death and Survival
Authors: Snoek Gerry
Published: November 2004

The actual cellular functions of the highly homologous small isoforms of the phosphatidylinositol transfer proteins, PI‐TPα and PI‐TPβ have been studied using many different experimental conditions varying from in vitro experiments with purified proteins and lipid vesicles to investigations in animals. In this review, the very diverse data of these investigations have been collected and joined to propose a model for the cellular functions of PI‐TPα and PI‐TPβ. The model is based on the suggested roles of PI‐TPα and PI‐TPβ in various lipid‐mediated cellular signaling pathways and leads to the conclusion that both proteins have a regulating function in pathways involved in the proliferation, apoptosis as well as survival of cells. IUBMB Life, 56: 467‐475, 2004
Respecting Sovereign States and Runnng a Tight Courtroom
Authors: Higgins Judge Rosalyn
Published: November 2004

There was a time when international law was perceived as consisting of a manageable corpus of rules over a finite, ascertainable subject matter, relevant to the relations of States with each other.
The Crime of Genocide: Nulyarimma v. Thompson
Authors: Daglish Kristen
Published: November 2004

On 31 May 1999 two matters came before the Full Federal Court of Australia, constituted by Justices Whitlam, Wilcox and Merkel. The two cases heard together were different in nature and origin, but their common feature was a claim of genocide. The primary issue was whether the international crime of genocide forms part of the law of Australia. The majority view was that, before an international crime could be prosecuted in an Australian court, specific domestic legislation needed to be enacted. The dissenting opinion was that genocide had become an offence at common law and could be prosecuted. In this case note I will analyse the opinions both in the terms of their impact on the relationship between international law and domestic law in Australia, and in light of recent trends in Australia and other common law countries.
How Effective is the European Security Architecture? Lessons from Bosnia and Kosovo
Authors: Wouters Jan , Naert Frederik
Published: November 2004

Security (in a broad sense, see infra, II.B) in Europe is the realm of several regional international organisations, mainly the European Union (“EU”), Western European Union (“WEU”), North Atlantic Treaty Organization (“NATO”), the Organization for Security and Co-operation in Europe (“OSCE”) and, to a lesser extent, the Council of Europe, creating a patchwork of regional security institutions that is unique in the world. These organisations interact in many ways and claim to be mutually reinforcing. Is that the case? Is there room for improvement?
Harmonisation of European Contract law the Influence of Comparative law
Authors: Berger Klaus Peter
Published: November 2004

It is generally acknowledged today that comparative law plays a decisive role in the harmonisation of European private law, in particular of European contract law.1 Dölle has emphasised this strong link between comparative law and European integration as early as 1950 in his report on the refoundation of the German Association of Comparative Law:
The Commission Communication on European Contract Law and the Future Prospects
Authors: Staudenmayer Dirk
Published: November 2004

On 11 July 2001 the Commission adopted its Communication on European Contract Law,1 which has received a lot of attention in academic discussion.2 In the following the main contents of the Commission Communication will first be summarised. In addition the political and institutional context shall be described which is important for the understanding of the Communication and the future prospects. Finally, we will try to demonstrate, how—according to the Council report3 and the European Parliament (EP) resolution4 concerning the Communication—these future prospects could develop4a.
I. ‘With or Without me’: The ECJ Adopts a Pose of Studied Neutrality Towards EU Enlargement
Authors: McMahon Joe , Pedain Antje
Published: November 2004

In three judgments delivered on 27 September 2001, the European Court of Justice ruled on the legal effects of clauses in the Europe Agreements which accord candidate country nationals limited rights to establish themselves as self-employed persons in the Member States of the European Union (EU).1 The Court refused to interpret these provisions as steps on the road to full-fledged EU membership which should be given a dynamic reading in order to provide continuing impetus for enlargement. The significance of these judgments lies less in their legal pronouncements than in their wider political implications. The judgments indicate that the Court is not prepared to act as a second chaperone of the process of enlargement alongside the Commission.
Reflections on Maritime Delimitation in the Qatar/Bahrain Case
Authors: Tanaka Yoshifumi
Published: November 2004

After nearly 10 years of proceedings before the International Court of Justice (ICJ), the Court, on 16 March 2001, rendered the decision concerning maritime delimitation and territorial questions between Qatar and Bahrain. One may identify two interesting features in this judgment. First, the ICJ, in the Qatar/Bahrain case (Merits), peacefully resolved a difficult dispute regarding territorial sovereignty as well as maritime delimitation.1 In this connection, a question which arises is the interrelation between territorial disputes and maritime delimitation.2 As will be seen later, the status of low-tide elevations, in particular, generated a serious disputes between the Parties. Secondly, the equidistance method was, for the first time in the case law of the ICJ, explicitly applied to a delimitation between States with adjacent coasts under customary law. Considering that the Court has been reluctant to apply the equidistance method to delimitations in situations of adjacency, this may be said to be a new development.
Legal Issues of EC–Cyprus Trade Relations
Authors: Koutrakos Panos
Published: November 2004

Whilst the political aspects of Cyprus's membership to the European Union have become the main focus of academic analysis over the years, its trade relations with the Member States have raised issues just as interesting from a legal point of view. This has been illustrated quite recently by the Anastasiou II judgment delivered by the European Court of Justice in 2000. The article aims at highlighting some of these issues. It is structured in three parts: the first part outlines the provisions of the EC–Cyprus Association Agreement governing trade between the parties; the second part analyses the Court's first ruling on imports of certain produce from the northern part of Cyprus;1 the third part examines the recent judgment of the Court on imports of produce which, whilst originating in the northern part of Cyprus, are being accompanied by phytosanitary certificates issued by the Turkish authorities.
Novel tools for visualizing and exploring intermolecular interactions in molecular crystals
Authors: McKinnon Joshua J. , Spackman Mark A. , Mitchell Anthony S.
Published: November 2004

A new way of exploring packing modes and intermolecular interactions in molecular crystals is described, using Hirshfeld surfaces to partition crystal space. These molecular Hirshfeld surfaces, so named because they derive from Hirshfeld's stockholder partitioning, divide the crystal into regions where the electron distribution of a sum of spherical atoms for the molecule (the promolecule) dominates the corresponding sum over the crystal (the procrystal). These surfaces reflect intermolecular interactions in a novel visual manner, offering a previously unseen picture of molecular shape in a crystalline environment. Surface features characteristic of different types of intermolecular interactions can be identified, and such features can be revealed by colour coding distances from the surface to the nearest atom exterior or interior to the surface, or by functions of the principal surface curvatures. These simple devices provide a striking and immediate picture of the types of interactions present, and even reflect their relative strengths from molecule to molecule. A complementary two-dimensional mapping is also presented, which summarizes quantitatively the types of intermolecular contacts experienced by molecules in the bulk and presents this information in a convenient colour plot. This paper describes the use of these tools in the compilation of a pictorial glossary of intermolecular interactions, using identifiable patterns of interaction between small molecules to rationalize the often complex mix of interactions displayed by large molecules.
Parameterization of the close packing of molecules in the unit cell
Authors: Pidcock Elna , Motherwell W. D. Sam
Published: November 2004

The box model of crystal packing describes unit cells in terms of a limited number of arrangements, or packing patterns, of molecular building blocks. Cell dimensions have been shown to relate to molecular dimensions in a systematic way. The distributions of pattern coefficients (cell length/molecular dimension) for thousands of structures belonging to P21/c, P\bar 1, P212121, P21 and C2/c are presented and are shown to be entirely consistent with the box model of crystal packing. Contributions to the form of the histograms from molecular orientation and molecular overlap are discussed. Gaussian fitting of the histograms has led to the parameterization of close packing within the unit cell and it is shown that molecular crystal structures are very similar to one another at a fundamental level.
Structural chemistry of new lithium bis(oxalato)borate solvates
Authors: Zavalij Peter Y. , Yang Shoufeng , Whittingham M. Stanley
Published: November 2004

Recently lithium bis(oxalato)borate, LiB(C2O4)2, has been proposed as an alternative lithium salt for the electrolyte in rechargeable batteries that do not contain explosive perchlorate, reactive fluoride or toxic arsenic. This lithium salt crystallizes in the form of solvates from such solvents as water, acetonitrile, acetone, dimethoxyethane, 1,3-dioxolane and ethylene carbonate. Their crystal structures were determined in order to explore the crystal chemistry of this lithium salt. It was found that most of the solvents consist of a lithium bis(oxalato)borate dimer in which the ligand acts as both a chelating and a bridging agent. Lithium has octahedral coordination that typically includes one or, less commonly, two solvent molecules. An exception to this rule is the ethylene carbonate solvate where the lithium is tetrahedrally surrounded exclusively by the solvent and bis(oxalato)borate plays the role of counter-ion only. The ethylene carbonate solvates were also studied for LiPF6 and LiAsF6 salts and they have similar structures to the bis(oxalato)borate tetrahedral complexes.
Herringbone Buckling Patterns of Compressed Thin Films on Compliant Substrates
Authors: Chen X. , Hutchinson John W.
Published: November 2004

A thin metal film vapor deposited on thick elastomer substrate develops an equi-biaxial compressive stress state when the system is cooled due to the large thermal expansion mismatch between the elastomer and the metal. At a critical stress, the film undergoes buckling into a family of modes with short wavelengths characteristic of a thin plate on a compliant elastic foundation. As the system is further cooled, a highly ordered herringbone pattern has been observed to develop. Here it is shown that the herringbone mode constitutes a minimum energy configuration among a limited set of competing modes.
Mechanics of Loading for Electroplated Cubic Boron Nitride (CBN) Wheels During Grinding of a Nickel-Based Superalloy in Water-Based Lubricating Fluids
Authors: Gift, Frank C. , Misiolek Wojciech Z. , Force Edwin
Published: November 2004

The mechanics of wheel loading of the nickel-based superalloy onto electroplated CBN wheels during grinding with water-based lubricants is proposed. Wheel loading was the primary cause for the significant decrease in grinding wheel life for the current formulation of water-based lubricants tested. Evidence of the specific sequence in the deposition process has been captured through extended evaluation and characterization of the grinding wheel surface and adherent alloy material. The proposed mechanism provides a phenomenological understanding of wheel loading for grinding operations using water-based lubricants, aiming to promote testing of future generation grinding lubricants and advanced fluid delivery methods specific to these operations.
Spreading of Novel Cyclotriphosphazine-Terminated PFPE Films on Carbon Surfaces
Authors: Tagawa Norio , Tateyama Tadao , Mori Atsunobu , Kobayashi Nagayoshi , Fujii Yoshinobu , Ikegami Masako
Published: November 2004

Spreading characteristics of novel cyclotriphosphazine-terminated Perfluoropolyether (PFPE) films on carbon surfaces were investigated experimentally by using a scanning micro-ellipsometer. The apparent diffusion coefficients of novel lubricants were also studied in order to evaluate the spreading speed and they were compared with the conventional Zdol. It was found that the mobility of cyclotriphosphazine-terminated PFPE films is lower than that of Zdol. This characteristics is dependent on the interactions between the end groups of the lubricants and carbon surfaces and it is found that the tendency of “work of adhesion” for the lubricants has a good correlation with the mobility tendency of the lubricants. In addition, the monolayer film thickness of novel lubricant films as well as conventional Zdol was identified, which was extracted using Matano interface method. As a result, the existing conformation of novel cyclotriphosphazine-terminated PFPE film on carbon surfaces could be estimated, based on the monolayer film thickness results.
Defect Green’s Function of Multiple Point-Like Inhomogeneities in a Multilayered Anisotropic Elastic Solid
Authors: Yang B.
Published: November 2004

Defect Green’s function (GF) of multiple point-like inhomogeneities in a multilayered solid has been derived within the theory of linear anisotropic elasticity. It is related to the (reference) GF of the multilayered matrix excluding the inhomogeneities through the continuum Dyson’s equation. While the reference GF is available, the defect GF can be solved. The expressions are first analytically reduced by realizing the point-likeness of the inhomogeneities. The subsequent procedure involves the solution of the response of each individual inhomogeneity to a far-field straining in the multilayered matrix and a matrix inversion on the order of the number of inhomogeneities. Furthermore, the defect GF is applied to derive the field induced by inhomogeneous substitutions in a multilayered solid. Numerical results are reported for arrays of cubic and semispherical Ge inclusions in a Si/Ge superlattice. The numerical results have demonstrated the validity and efficiency of the present formulation.
A General Solution for Two-Dimensional Stress Distributions in Thin Films
Authors: Krishnamurthy R. , Srolovitz D. J.
Published: November 2004

We present closed-form solutions for stresses in a thin film resulting from a purely dilatational stress-free strain that can vary arbitrarily within the film. The solutions are specific to a two-dimensional thin film on a thick substrate geometry and are presented for both a welded and a perfectly slipping film/substrate interface. Variation of the stress-free strain through the thickness of the film is considered to be either arbitrary or represented by a Fourier integral, and solutions are presented in the form of a Fourier series in the lateral dimension x. The Fourier coefficients can be calculated rapidly using Fast Fourier Transforms. The method is applied to determine the stresses in the film and substrate for three cases: (a) where the stress-free strain is a sinusoidal modulation in x, (b) where the stress-free strain varies only through the thickness, and (c) where a rectangular inclusion is embedded within the film, and the calculated stresses match accurately with the exact solutions for these cases.
Formation of Microscopic Voids in Resin Transfer Molded Composites
Authors: Hamidi Youssef K. , Aktas Levent , Altan M. Cengiz
Published: November 2004

Performance of composite materials usually suffers from process-induced defects such as dry spots and microscopic voids. While effects of void content in molded composites have been studied extensively, knowledge of void morphology and spatial distribution of voids in composites manufactured by resin transfer molding (RTM) remains limited. In this study, through-the-thickness void distribution for a disk-shaped, E-glass/epoxy composite part manufactured by resin transfer molding is investigated. Microscopic image analysis is conducted through-the-thickness of a radial sample obtained from the molded composite disk. Voids are found to concentrate primarily within or adjacent to the fiber preforms. More than 93% of the voids are observed within the preform or in a so-called transition zone, next to a fibrous region. In addition, void content was found to fluctuate through-the-thickness of the composite. Variation up to 17% of the average void content of 2.15% is observed through-the-thicknesses of the eight layers studied. Microscopic analysis revealed that average size of voids near the mold surfaces is slightly larger than those located at the interior of the composite. In addition, average size of voids that are located within the fiber preform is observed to be smaller than those located in other regions of the composite. Finally, proximity to the surface is found to have no apparent effect on shape of voids within the composite.
Thermal Shock Strength of a Semi-infinite Piezoelectric Medium
Authors: Wang Bao-Lin , Sun Yu-Guo
Published: November 2004

This paper considers the mechanical problem of a semi-infinite piezoelectric medium under sudden thermal load. The medium contains an electrically conducting crack perpendicular to its surface. The transient stresses and electric fields in an uncracked medium are calculated first. Then, these stresses and electric fields are used as the crack surface traction and electric field loads with opposite signs to formulate the mixed boundary value problem. Numerical results for the stress and electric field intensity factors are calculated as a function of normalized time and crack size. Crack propagation behavior is discussed. The parameters that control the transient thermal stress and electric fields are also identified. The maximum thermal shock strength that the material can sustain without catastrophic failure is established according to two distinct criteria: (i) maximum local tensile stress equals the tensile strength of the medium, and (ii) maximum stress intensity factor for the preexisting representative crack equals the fracture toughness of the medium. The results show that the influence of the piezoelectric effects on the thermal stress intensity factor is insignificant.
Microstructural Characterization of Ti-6Al-4V Subjected to Fretting
Authors: Swalla Dana R. , Neu Richard W. , McDowell David L.
Published: November 2004

This study is focused on characterization of microstructural changes linked to deformation and crack formation mechanisms in duplex Ti-6Al-4V specimens used in displacement controlled fretting-only experiments. In particular, the effect of slip displacement amplitude and number of fretting cycles on the evolution of grain morphology, grain orientation, misorientation distribution, composition, and microhardness is investigated using electron backscatter diffraction (EBSD), energy dispersive X-ray analysis (EDX), and nanoindentation. A strong basal microtexture and significant oxygen diffusion were observed in the Ti-6Al-4V specimen that exhibited the most significant cracking. A critical slip amplitude threshold may exist for which a combination of mechanisms, such as plastic deformation, grain reorientation, and oxygen diffusion, occur during fretting that make conditions ideal for crack formation. The results provide insights for development and validation of computational crystal plasticity models with application to fretting and sliding contact problems. New fretting damage-assessment measures have also been identified and have application for components that suffer from fretting wear and/or fatigue related failures.
Actual Eyring Models for Thixotropy and Shear-Thinning: Experimental Validation and Application to EHD
Authors: Bair Scott
Published: November 2004

The Eyring sinh law is presently the most well-accepted model for shear-thinning of EHD lubricants at high pressure. It was, however, not accepted for this purpose by Eyring, who found it to be of only limited usefulness for thixotropy. Then, it is extremely important that these models receive a critical review using data obtained by modern methods to evaluate the actual Eyring models and show how they differ from the model in use today. Data from high-pressure viscometers were used to validate the actual Eyring models. The Ree-Eyring model for shear-thinning obeys time-temperature-pressure superposition. A film thickness calculation shows it to suffer from the same anomalous behavior in sliding contact as does the sinh law.
Direct Visualization of Molecularly Thin Lubricant Films on Magnetic Disks by Ellipsometric Microscopy With a White Light Source
Authors: Fukuzawa Kenji , Nakada Akira , Mitsuya Yasunaga , Zhang Hedong
Published: November 2004

We demonstrated the direct visualization of molecularly thin lubricant films on magnetic disks with a thickness resolution of 0.1 nm by using an ellipsometric microscope with a white light source. It was able to reduce the optical interference noise that arises in conventional laser-based ellipsometric microscopes and to provide a larger SNR by a factor of about 6 compared to a laser-based ellipsometric microscope. The wavelength width should be given first priority in designing a white-light-source ellipsometric microscope, and the width should be determined after considering the required coherence length and thickness resolution. Theoretical calculations indicate that a wavelength width of less than 10 nm can provide a thickness resolution of 0.1 nm. A white-light-source ellipsometric microscope can provide real-time visualization of a molecularly thin lubricant film with a thickness resolution of 0.1 nm, which is useful in investigating the kinetic behavior of molecularly thin lubricant films on magnetic disks.
Sound field modeling in a street canyon with partially diffusely reflecting boundaries by the transport theory
Authors: Le Pollès Thierry , Picaut Judicaël , Bérengier Michel , Bardos Claude
Published: November 2004

The transport theory, applied to the concept of sound particles, seems to be well adapted to predict the sound propagation in urban areas, including most complex effects, like diffuse scattering by building facades, atmospheric attenuation, scattering by urban objects in streets, etc. In this paper, the transport theory is then applied to the sound field modeling in an empty street canyon with partially diffusely building facades. In this case, the temporal and spatial distribution of sound energy in a street is the solution of a transport equation, with mixed specular-diffuse boundary conditions. Using an asymptotic approach, the transport equation may be reduced to a diffusion equation for the sound energy, where the diffusion coefficient depends only on the building facades properties. Comparisons with experiments show that the diffusion model gives consistent results with experimental data, both for the sound attenuation level and the reverberation time.
Line source representation for laser-generated ultrasound in an elastic transversely isotropic half-space
Authors: Hurley David H. , Spicer James B.
Published: November 2004

Theoretical and experimental results are presented for a laser line source in an elastic, transversely isotropic half-space. The thermoelastic source (laser source) is represented as an appropriately weighted shear stress dipole applied at the sample surface. The plane of isotropy coincides with the half-space boundary. Analytical expressions representing the out-of-plane displacements for the surface wave and for the epicentral cases are given for all crystal classes that exhibit elastic transverse isotropy. In addition, quasianalytical results are given for observation points off the epicentral axis. Theoretical wave forms for all of the source/observation geometries considered are compared with experimental wave forms generated in single crystal zinc samples. The close comparison between experiment and theory confirms, for this particular line source orientation and crystal symmetry, that a laser line source is accurately modeled using an equivalent boundary stress.
Source localization in complex listening situations: Selection of binaural cues based on interaural coherence
Authors: Faller Christof , Merimaa Juha
Published: November 2004

In everyday complex listening situations, sound emanating from several different sources arrives at the ears of a listener both directly from the sources and as reflections from arbitrary directions. For localization of the active sources, the auditory system needs to determine the direction of each source, while ignoring the reflections and superposition effects of concurrently arriving sound. A modeling mechanism with these desired properties is proposed. Interaural time difference (ITD) and interaural level difference (ILD) cues are only considered at time instants when only the direct sound of a single source has non-negligible energy in the critical band and, thus, when the evoked ITD and ILD represent the direction of that source. It is shown how to identify such time instants as a function of the interaural coherence (IC). The source directions suggested by the selected ITD and ILD cues are shown to imply the results of a number of published psychophysical studies related to source localization in the presence of distracters, as well as in precedence effect conditions.
Analytic treatment of the compound action potential: Estimating the summed post-stimulus time histogram and unit response
Authors: Chertoff Mark E.
Published: November 2004

The convolution of an equation representing a summed post-stimulus time histogram computed across auditory nerve fibers [P(t)] with an equation representing a single-unit wave form [U(t)], resulted in an analytic expression for the compound action potential (CAP). The solution was fit to CAPs recorded to low and high frequency stimuli at various signal levels. The correlation between the CAP and the analytic expression was generally greater than 0.90. At high levels the width of P(t) was broader for low frequency stimuli than for high frequency signals, but delays were comparable. This indicates that at high signal levels there is an overlap in the population of auditory nerve fibers contributing to the CAP for both low and high frequency stimuli but low frequencies include contributions from more apical regions. At low signal levels the width of P(t) decreased for most frequencies and delays increased. The frequency of oscillation of U(t) was largest for high frequency stimuli and decreased for low frequency stimuli. The decay of U(t) was largest at 8 kHz and smallest at 1 kHz. These results indicate that the hair cell or neural mechanisms involved in the generation of action potentials may differ along the cochlear partition.
On the interference between the two microphones in free-field reciprocity calibration
Authors: Barrera-Figueroa Salvador , Rasmussen Knud , Jacobsen Finn , Muñı́z Lorenzo
Published: November 2004

One of the fundamental assumptions in free-field reciprocity calibration of microphones is that the microphones can be substituted by point sources at the positions where the acoustic centers are located. However, in practice the microphones have finite dimensions and, at the distance and in the frequency range where the measurements are made, the direct wave and the subsequent reflections from the microphones interfere with each other, creating a “standing wave.” This interference effect gives rise to deviations from the inverse distance law, indicating that the free-field assumption is not strictly valid. The interference has been thought to be caused by specular reflection between the parallel diaphragms of the microphones, and a solution based on tilting the axis of one of the microphones a few degrees has been proposed, but never examined in practice. In this paper a time-selective technique is applied for analyzing the interference and for removing it in the time domain. It is shown that the phenomenon is due to multiple backscattering rather than specular reflection. Thus tilting one of the microphones does not alleviate the problem, as also demonstrated experimentally. However, the time-selective technique is quite effective in removing the interference effect and other disturbances from the direct wave between the microphones.
Using light scattering to measure the response of individual ultrasound contrast microbubbles subjected to pulsed ultrasound in vitro
Authors: Guan Jingfeng , Matula Thomas J.
Published: November 2004

Light scattering was used to measure the radial pulsations of individual ultrasound contrast microbubbles subjected to pulsed ultrasound. Highly diluted Optison® or Sonazoid® microbubbles were injected into either a water bath or an aqueous solution containing small quantities of xanthan gum. Individual microbubbles were insonified by ultrasound pulses from either a commercial diagnostic ultrasound machine or a single element transducer. The instantaneous response curves of the microbubbles were measured. Linear and nonlinear microbubble oscillations were observed. Good agreement was obtained by fitting a bubble dynamics model to the data. The pulse-to-pulse evolution of individual microbubbles was investigated, the results of which suggest that the shell can be semipermeable, and possibly weaken with subsequent pulses. There is a high potential that light scattering can be used to optimize diagnostic ultrasound techniques, understand microbubble evolution, and obtain specific information about shell parameters.
Analytical-numerical matching for fluid-loaded structures with discontinuities
Authors: Park Christopher D. , Franzoni Linda P. , Bliss Donald B.
Published: November 2004

The method of analytical-numerical matching (ANM) is applied to several example problems involving the radiation and vibration of a fluid-loaded cylindrical shell with structural discontinuities. These problems are used to verify the accuracy of the method compared to a purely numerical approach, and to demonstrate the usefulness of ANM for solving problems involving nonaxisymmetric forcing and constraints on structures that are otherwise axisymmetric. The principal advantage of the ANM method for this application is its ability to employ a spectral method (modal decomposition in azimuth) in the solution of a problem that is nonaxisymmetric. ANM divides the original problem into local and global subproblems that are solved separately. The discontinuity is handled using a high-resolution local finite-element model. Smooth forces are derived from solving an analytical matching problem on the local domain, and these smooth forces are then applied to a low-resolution numerical global problem. The superposition of solutions to the subproblems is equivalent to the solution of the original problem. For fluid loading, the local high-resolution model is solved in vacuo, and the effects of fluid loading are included completely by the low-resolution global problem.
Sample discrimination of frequency differences with distracters
Authors: Neff Donna L. , Odgaard Eric C.
Published: November 2004

This study examined the effect of the type and frequency range of remote frequency distracters on sample discrimination of frequency differences (SD-F). For baseline SD-F conditions, normal-hearing listeners judged frequency differences between pairs of target tones drawn from Gaussian frequency distributions near 2000 Hz. In experiment 1, the distracters were pairs of random-frequency tones, fixed-frequency tones, or noise bands, with one distracter above and one below the target region. Three frequency separations of targets and distracters were tested, none overlapping the target region. Effects of fixed-frequency or noise-band distracters were small compared to that of random-frequency distracters, which drove performance to near chance. In experiment 2, dominance of the low-frequency distracter was supported by the effects of changing distracter level, by presenting only the higher- or lower-frequency distracter, and by the pattern of weights derived from trial-by-trial responses. Performance recovered only when the lower-frequency distracter was attenuated 40–50 dB relative to the targets. In experiment 3, all stimulus distributions were shifted 2 octaves higher in frequency; the stronger influence of the distracter frequency below the target remained. The results demonstrate the importance of both stimulus variability and frequency relationships in the interaction of targets and distracters for SD-F.
Response of the cat eardrum to static pressures: Mobile versus immobile malleus
Authors: Ladak Hanif M. , Decraemer Willem F. , Dirckx Joris J. J. , Funnell W. Robert J.
Published: November 2004

A phase-shift shadow moiré interferometer was used to measure the shape of the cat eardrum with a normal mobile malleus and with an immobile malleus as it was cyclically loaded with static middle-ear pressures up to ±2.2 kPa. The shape was monitored throughout the loading and unloading phases, and three complete cycles were observed. The mobile-manubrium measurements were made in five ears. In three ears, the malleus was then immobilized with a drop of glue placed on the head of the malleus. Eardrum displacements were calculated by subtracting shape images pixel by pixel. The measurements are presented in the form of gray-level full-field shape and displacement images, of displacement profiles, and of pressure-displacement curves for selected points. Displacement patterns with a mobile malleus show that pars-tensa displacements are larger than manubrial displacements, with the maximum pars-tensa displacement occurring in the posterior region in all cats except one. Displacements vary from cycle to cycle and display hysteresis. For both the mobile-malleus and immobile-malleus cases, the eardrum response is nonlinear. The response is asymmetric, with lateral displacements being larger than medial displacements. With a mobile malleus, manubrial displacements exhibit more pronounced asymmetry than do pars-tensa displacements.