bluuebunny/crossref_metadata_2025 huggingface dataset:
Weight Management in Amateur Wrestling
Authors: Gibbs Aimee E. , Pickerman Joel , Sekiya Jon K.
Published: May 2009

Context:

Unhealthy weight loss practices continue to plague amateur wrestling. The National Collegiate Athletic Association weight loss guidelines are beneficial but have not solved the problem.

Evidence Acquisition:

All relevant databases through 2008 were searched using PubMed. The references of relevant articles were then searched for additional publications.

Study Type:

Clinical review.

Results:

New rules approved by the National Collegiate Athletic Association have been implemented in an attempt to prevent drastic weight loss practices in wrestlers. Although some are effective, such as establishing a minimum wrestling weight and decreasing the period between weigh-ins and actual wrestling, unsafe weight loss practices still occur.

Conclusion:

The attempts made by the National Collegiate Athletic Association to prevent drastic weight loss in wrestling have been effective to some degree. The mind-set of athletes, coaches, and clinicians needs to change if further improvements are to be made.
PAF-acetylhydrolase expressed during megakaryocyte differentiation inactivates PAF-like lipids
Authors: Foulks Jason M. , Marathe Gopal K. , Michetti Noemi , Stafforini Diana M. , Zimmerman Guy A. , McIntyre Thomas M. , Weyrich Andrew S.
Published: April 2009

Platelet activating factor (PAF) and PAF-like lipids induce inflammatory responses in target cells. These lipid mediators are inactivated by PAF-acetylhydrolase (PAF-AH). The PAF signaling system affects the growth of hematopoietic CD34+ cells, but roles for PAF-AH in this process are unknown. Here, we investigated PAF-AH function during megakaryopoiesis and found that human CD34+ cells accumulate this enzymatic activity as they differentiate toward megakaryocytes, consistent with the expression of mRNA and protein for the plasma PAF-AH isoform. Inhibition of endogenous PAF-AH activity in differentiated megakaryocytes increased formation of lipid mediators that signaled the PAF receptor (PAFR) in fully differentiated human cells such as neutrophils, as well as megakaryocytes themselves. PAF-AH also controlled megakaryocyte αIIbβ3-dependent adhesion, cell spreading, and mobility that relied on signaling through the PAFR. Together these data suggest that megakaryocytes generate PAF-AH to modulate the accumulation of intracellular phospholipid mediators that may detrimentally affect megakaryocyte development and function.
Vδ1 T lymphocytes producing IFN-γ and IL-17 are expanded in HIV-1–infected patients and respond to Candida albicans
Authors: Fenoglio Daniela , Poggi Alessandro , Catellani Silvia , Battaglia Florinda , Ferrera Alessandra , Setti Maurizio , Murdaca Giuseppe , Zocchi Maria Raffaella
Published: April 2009

In early HIV-1 infection, Vδ1 T lymphocytes are increased in peripheral blood and this is related to chemokine receptor expression, chemokine response, and recirculation. Herein we show that, at variance with healthy donors, in HIV-1–infected patients ex vivo–isolated Vδ1 T cells display cytoplasmic interferon-γ (IFN-γ). Interestingly, these cells coexpress cytoplasmic interleukin-17 (IL-17), and bear the CD27 surface marker of the memory T-cell subset. Vδ1 T cells, isolated from either patients or healthy donors, can proliferate and produce IFN-γ and IL-17 in response to Candida albicans in vitro, whereas Vδ2 T cells respond with proliferation and IFN-γ/IL-17 production to mycobacterial or phosphate antigens. These IFN-γ/IL-17 double-producer γδ T cells express the Th17 RORC and the Th1 TXB21 transcription factors and bear the CCR7 homing receptor and the CD161 molecule that are involved in γδ T-cell transendothelial migration. Moreover, Vδ1 T cells responding to C albicans express the chemokine receptors CCR4 and CCR6. This specifically equipped circulating memory γδ T-cell population might play an important role in the control of HIV-1 spreading and in the defense against opportunistic infections, possibly contributing to compensate for the impairment of CD4+ T cells.
NK cell–mediated killing of target cells triggers robust antigen-specific T cell–mediated and humoral responses
Authors: Krebs Philippe , Barnes Michael J. , Lampe Kristin , Whitley Karen , Bahjat Keith S. , Beutler Bruce , Janssen Edith , Hoebe Kasper
Published: May 2009

Previous work showed that administration of antigen-expressing apoptotic cells in vivo results in antigen-specific CD8+ T-cell responses independent of Toll-like receptor signaling. We report here that natural killer (NK) cells can serve a function directly upstream of this pathway and initiate robust adaptive immune responses via killing of antigen-expressing target cells. This pathway is highly sensitive, in that administration of as few as 104 target cells induced detectable antigen-specific CD8+ T-cell responses. Importantly, NK cell–mediated cytotoxicity of target cells could also induce robust antigen-specific CD4+ T-cell responses, which were critical for subsequent CD8+ T-cell priming and IgG responses. Unlike adaptive immune responses induced by gamma-irradiated cells, the NK-cell pathway required myeloid differentiating factor 88 (MyD88) and Toll/interleukin-1 receptor domain–containing adapter-inducinginterferon-β (Trif) signaling. NK cells have previously been shown to detect and kill pathogen-infected host cells, as well as neoplastic cells and tissue allografts. The present data provide further evidence that they also discharge a strong tie with their relatives in the adaptive immune system. We think that the recognition and killing of target cells by NK cells represents an important pathway for the generation of robust CD8+ T and humoral responses that may be exploited for vaccine development.
Discordance of MLL-rearranged (MLL-R) infant acute lymphoblastic leukemia in monozygotic twins with spontaneous clearance of preleukemic clone in unaffected twin
Authors: Chuk Meredith K. , McIntyre Emily , Small Donald , Brown Patrick
Published: May 2009

Concordance of MLL-rearranged acute leukemia in infant monozygotic twins is thought to be 100% with a very short latency period, suggesting that either the MLL fusion itself is sufficient to cause leukemia or that it promotes the rapid acquisition of additional oncogenic events that result in overt disease. We report the first case of discordance in an infant monozygotic twin pair. Twin A presented at age 9 months with MLL-ENL+ acute lymphoblastic leukemia and twin B remains healthy 3 years later. The presence and eventual clearance of a clonal population of MLL-ENL+ cells was shown in the bone marrow and peripheral blood of twin B. Clearance of this clone was temporally associated with viral-induced cytopenias, suggesting an immune-mediated clearance of the clone before the development of leukemia. Thus, concordance of MLL-rearranged acute leukemia in infant monozygotic twins is not universal. The implications of this case for MLL-rearranged leukemogenesis are discussed.
Involvement of TLR2 and TLR4 in inflammatory immune responses induced by fine and coarse ambient air particulate matter
Authors: Shoenfelt Joanna , Mitkus Robert J , Zeisler Rolf , Spatz Rabia O , Powell Jan , Fenton Matthew J , Squibb Katherine A , Medvedev Andrei E
Published: May 2009

Fine and coarse air pollution particles signal macrophage activation via differential utilization of Toll-like receptors (TLR) 2 and TLR4 but shared use of the MyD88 signaling pathway.

Induction of proinflammatory mediators by alveolar macrophages exposed to ambient air particulate matter has been suggested to be a key factor in the pathogenesis of inflammatory and allergic diseases in the lungs. However, receptors and mechanisms underlying these responses have not been fully elucidated. In this study, we examined whether TLR2, TLR4, and the key adaptor protein, MyD88, mediate the expression of proinflammatory cytokines and chemokines by mouse peritoneal macrophages exposed to fine and coarse PM. TLR2 deficiency blunted macrophage TNF-α and IL-6 expression in response to fine (PM2.5), while not affecting cytokine-inducing ability of coarse NIST Standard Reference Material (SRM 1648) particles. In contrast, TLR4−/− macrophages showed inhibited cytokine expression upon stimulation with NIST SRM 1648 but exhibited normal responses to PM2.5. Preincubation with polymyxin B markedly suppressed the capacity of NIST SRM 1648 to elicit TNF-α and IL-6, indicating endotoxin as a principal inducer of cytokine responses. Overexpression of TLR2 in TLR2/4-deficient human embryonic kidney 293 cells imparted PM2.5 sensitivity, as judged by IL-8 gene expression, whereas NIST SRM 1648, but not PM2.5 elicited IL-8 expression in 293/TLR4/MD-2 transfectants. Engagement of TLR4 by NIST SRM 1648 induced MyD88-independent expression of the chemokine RANTES, while TLR2-reactive NIST IRM PM2.5 failed to up-regulate this response. Consistent with the shared use of MyD88 by TLR2 and TLR4, cytokine responses of MyD88−/− macrophages to both types of air PM were significantly reduced. These data indicate differential utilization of TLR2 and TLR4 but shared use of MyD88 by fine and coarse air pollution particles.
Liver X receptor agonist regulation of Th17 lymphocyte function in autoimmunity
Authors: Xu Jihong , Wagoner Gail , Douglas James C , Drew Paul D
Published: May 2009

LXR agonists alter Th17 cell function and suppress EAE.

CD4+ Th17 cells are believed to play an important role in the development of a variety of autoimmune diseases including EAE, an animal model of MS. Previously, we and others demonstrated that LXR agonists suppressed the activation of primary glial cells and blocked the development of EAE. The present studies demonstrated that the LXR agonist T0901317 suppressed IL-17A expression from splenocytes derived from Vα2.3/Vβ8.2 TCR transgenic mice and from MOG35–55-immunized C57BL/6 mice. Furthermore, in vitro treatment with IL-23 alone or in combination with MOG35–55 induced IL-17A expression from splenocytes derived from MOG35–55-immunized mice, and T0901317 blocked this induction. In vitro treatment with the LXR agonist suppressed IL-23R expression by splenocytes. In addition, in vivo treatment with the LXR agonist suppressed IL-17A and IL-23R mRNA and protein expression in EAE mice. These studies suggest that LXR agonists suppress EAE, at least in part by suppressing IL-23 signaling. Recent studies indicate that the cytokines IL-21 and IL-22 are produced by Th17 cells and modulate immune responses. Our studies demonstrate that the LXR agonist T0901317 suppressed MOG35–55-induced expression of IL-21 and IL-22 mRNA in splenocytes derived from MOG35–55-immunized mice. Finally, we demonstrate that the LXR agonist T0901317 suppressed the development of EAE in an experimental paradigm involving treatment of established EAE. Collectively, these studies suggest that LXR agonists may be effective in the treatment of MS.
Functional implication of BAFF synthesis and release in gangliosides-stimulated microglia
Authors: Kim Kwang Soo , Park Ji-Young , Jou Ilo , Park Sang Myun
Published: May 2009

BAFF and BAFF receptors, which are expressed in microglia, may play an important role in CNS inflammation.

BAFF is a recently identified member of the TNF ligand superfamily that plays a critical role in B cell differentiation, survival, and regulation of Ig production. In the present study, we examined whether BAFF is expressed in microglia, and the expression and release of BAFF are regulated by gangliosides. The results showed that BAFF was expressed and released in rat primary microglia as well as in BV-2 cells. Furthermore, its expression and release were increased by gangliosides stimulation and regulated by JAK-STAT, especially the STAT1- and STAT3-dependent signaling pathways. It was of particular interest to observe that SP600125 and SB203580, specific inhibitors of JNK and p38, did not inhibit BAFF synthesis but inhibited the release of sBAFF in gangliosides-treated cells by regulating furin expression, suggesting that the JNK and p38 signaling pathways regulate the release but not the synthesis of BAFF. Moreover, BV-2 cells expressed BAFF-R on their cell surface, and rat primary microglia expressed BAFF-R and TACI on their cell surface. rBAFF increased the release of cytokines, especially IL-6, TNF-α, and IL-10, in rat primary microglia as well as in BV-2 cells. These findings imply that BAFF secreted by microglia may play important roles in CNS inflammation by regulating microglia as well as infiltrated B cells.
Inverse correlation between HPSE gene single nucleotide polymorphisms and heparanase expression: possibility of multiple levels of heparanase regulation
Authors: Ostrovsky Olga , Korostishevsky Michael , Shafat Itay , Mayorov Margarita , Ilan Neta , Vlodavsky Israel , Nagler Arnon
Published: May 2009

Combination of two HPSE gene single nucleotide polymorphisms predicts heparanase expression levels and possibly disease outcome.

Heparanase is an endo-β-glucuronidase that specifically cleaves the saccharide chains of heparan sulfate proteoglycans. Heparanase plays important roles in processes such as angiogenesis, tumor metastasis, tissue repair and remodeling, inflammation and autoimmunity. Genetic variations of the heparanase gene (HPSE) have been associated with heparanase transcription level. The present study was undertaken to identify haplotype or single nucleotide polymorphisms (SNPs) genotype combinations that correlate with heparanase expression both at the mRNA and protein levels. For this purpose, 11 HPSE gene SNPs were genotyped among 108 healthy individuals. Five out of the eleven polymorphisms revealed an association between the SNPs and heparanase expression. SNP rs4693608 exhibited a strong evidence of association. Analysis of haplotypes distribution revealed that the combination of two SNPs (rs4693608 and rs4364254) disclosed the most significant result. This approach allowed segregation of possible genotype combinations to three groups that correlate with low (LR: GG-CC, GG-CT, GG-TT, GA-CC), intermediate (MR: GA-CT, GA-TT) and high (HR: AA-TT, AA-CT) heparanase expression. Unexpectedly, LR genotype combinations were associated with low mRNA expressions level and high heparanase concentration in plasma, while HR genotype combinations were associated with high expression of mRNA and low plasma protein level. Because the main site of activity of secreted active heparanase is the extracellular matrix and cell surface, the origin and functional significance of plasma heparanase remain to be investigated. The current study indicates that rs4693608 and rs4364254 SNPs are involved in the regulation of heparanase expression and provides the basis for further studies on the association between HPSE gene SNPs and disease outcome.
Hemopexin down-regulates LPS-induced proinflammatory cytokines from macrophages
Authors: Liang Xueya , Lin Tian , Sun Guangjie , Beasley-Topliffe Laura , Cavaillon Jean-Marc , Warren H Shaw
Published: April 2009

The heme-binding protein hemopexin limits TLR4 and TLR2 agonist-induced macrophage cytokine production through a mechanism distinct from heme oxygenase-1.

Detection of LPS in tissues is an integral component of innate immunity that acts to protect against invasion by Gram-negative bacteria. Plasma down-regulates LPS-induced cytokine production from macrophages, thereby limiting systemic inflammation in blood and distant tissues. To identify the protein(s) involved in this process, we used classical biochemical chromatographic techniques to identify fractions of mouse sera that suppress LPS-induced TNF from bone marrow-derived macrophages (BMDMs). Fractionation yielded microgram quantities of a protein that was identified by MS to be hemopexin (Hx). Mouse Hx purified on hemin-agarose beads and rhHx decreased the production of cytokines from BMDMs and peritoneal macrophages induced by LPS. Preincubation of LPS with Hx did not affect the activity of LPS on LAL, whereas preincubation of Hx with macrophages followed by washing resulted in decreased activity of these cells in response to LPS, suggesting that Hx acts on macrophages rather than LPS. Heme-free Hx did not stimulate HO-1 in the macrophages. Purified Hx also decreased TNF and IL-6 from macrophages induced by the synthetic TLR2 agonist Pam3Cys. Our data suggest that Hx, which is an acute-phase protein that increases during inflammation, limits TLR4 and TLR2 agonist-induced macrophage cytokine production directly through a mechanism distinct from HO-1.
Immune-based therapy for chronic hepatitis C
Authors: Chang Dong-Yeop , Shin Eui-Cheol
Published: April 2009

Development of novel therapies for chronic hepatitis C by modulating innate and adaptive immune responses are reviewed.

Chronic, persistent HCV infection is a public health issue. It often progresses to life-threatening complications, including liver cirrhosis and hepatocellular carcinoma. The current standard therapy is a combination of pegylated IFN-α and ribavirin. This therapy results in a sustained virologic response in only 50% of patients infected with HCV genotype 1 and is often accompanied with substantial side-effects. Therefore, it is imperative to develop novel therapies with higher efficacy and less substantial side-effects. Impaired immune responses to HCV are key features of chronic HCV infection; thus, intervention strategies typically involve boosting the immune responses against HCV. These immune-based therapies for chronic HCV infection include therapeutic vaccines, antagonists of T cell inhibitory factors, anti-HCV neutralizing antibodies, cytokines, and agonists for TLRs. Currently, various types of immune-based therapies are under development that might be used as a monotherapy or in combination with other antiviral drugs for the treatment of chronic HCV infection.
Estrogens Augment Cell Surface TLR4 Expression on Murine Macrophages and Regulate Sepsis Susceptibility in Vivo
Authors: Rettew Jennifer A. , Huet Yvette M. , Marriott Ian
Published: May 2009

Gender-based differences exist in infectious disease susceptibility. In general, females generate more robust and potentially protective humoral and cell-mediated immune responses after antigenic challenge than their male counterparts. Furthermore, evidence is accumulating that sex may also influence the early perception of microbial challenges and the generation of inflammatory immune responses such as sepsis. These differences have previously been attributed to the actions of reproductive hormones. Whereas androgens have been shown to suppress acute host immune responses to bacterial endotoxin challenge, estrogens have been found to promote increased resistance to bacterial infections. However, the mechanisms by which estrogens exert immunoprotective effects have not been established. In this study, we investigated the in vivo effects of 17β-estradiol on endotoxin susceptibility in mice. Importantly, we have examined the actions of this female reproductive hormone on the expression of pattern recognition receptors that recognize bacterial endotoxin by key innate immune sentinel cells. We show that removal of endogenous estrogens decreases both pro- and antiinflammatory cytokine production, with a concomitant reduction in circulating levels of lipopolysaccharide-binding protein and cell surface expression of Toll-like receptor 4 on murine macrophages. Exogenous in vivo replacement of 17β-estradiol, but not progesterone, significantly elevates sera lipopolysaccharide-binding protein levels and cell surface expression of Toll-like receptor 4 and CD14 on macrophages. Furthermore, this effect corresponds with significantly higher inflammatory cytokine levels after in vivo lipopolysaccharide challenge and a marked increase in endotoxin-associated morbidity. Taken together, these data provide a potential mechanism underlying the immunoenhancing effects of estrogens.
Using computational fluid dynamics to calculate the stimulus to the lateral line of a fish in still water
Authors: Rapo Mark A. , Jiang Houshuo , Grosenbaugh Mark A. , Coombs Sheryl
Published: May 2009

This paper presents the first computational fluid dynamics (CFD)simulations of viscous flow due to a small sphere vibrating near a fish, a configuration that is frequently used for experiments on dipole source localization by the lateral line. Both two-dimensional (2-D) and three-dimensional (3-D) meshes were constructed, reproducing a previously published account of a mottled sculpin approaching an artificial prey. Both the fish-body geometry and the sphere vibration were explicitly included in the simulations. For comparison purposes, calculations using potential flow theory (PFT) of a 3-D dipole without a fish body being present were also performed. Comparisons between the 2-D and 3-D CFD simulations showed that the 2-D calculations did not accurately represent the 3-D flow and therefore did not produce realistic results. The 3-D CFD simulations showed that the presence of the fish body perturbed the dipole source pressure field near the fish body, an effect that was obviously absent in the PFT calculations of the dipole alone. In spite of this discrepancy, the pressure-gradient patterns to the lateral line system calculated from 3-D CFD simulations and PFT were similar. Conversely, the velocity field, which acted on the superficial neuromasts (SNs), was altered by the oscillatory boundary layer that formed at the fish's skin due to the flow produced by the vibrating sphere (accounted for in CFD but not PFT). An analytical solution of an oscillatory boundary layer above a flat plate, which was validated with CFD, was used to represent the flow near the fish's skin and to calculate the detection thresholds of the SNs in terms of flow velocity and strain rate. These calculations show that the boundary layer effects can be important, especially when the height of the cupula is less than the oscillatory boundary layer's Stokes viscous length scale.
Characterization of obstacle negotiation behaviors in the cockroach,Blaberus discoidalis
Authors: Harley C. M. , English B. A. , Ritzmann R. E.
Published: May 2009

Within natural environments, animals must be able to respond to a wide range of obstacles in their path. Such responses require sensory information to facilitate appropriate and effective motor behaviors. The objective of this study was to characterize sensors involved in the complex control of obstacle negotiation behaviors in the cockroach Blaberus discoidalis. Previous studies suggest that antennae are involved in obstacle detection and negotiation behaviors. During climbing attempts, cockroaches swing their front leg that then either successfully reaches the top of the block or misses. The success of these climbing attempts was dependent on their distance from the obstacle. Cockroaches with shortened antennae were closer to the obstacle prior to climbing than controls, suggesting that distance was related to antennal length. Removing the antennal flagellum resulted in delays in obstacle detection and changes in climbing strategy from targeted limb movements to less directed attempts. A more complex scenario – a shelf that the cockroach could either climb over or tunnel under – allowed us to further examine the role of sensory involvement in path selection. Ultimately, antennae contacting the top of the shelf led to climbing whereas contact on the underside led to tunneling However, in the light, cockroaches were biased toward tunnelling; a bias which was absent in the dark. Selective covering of visual structures suggested that this context was determined by the ocelli.
Modelling evolution of saccular cerebral aneurysms
Authors: Watton P , Ventikos Y
Published: May 2009

A computational model for the evolution of a saccular cerebral aneurysm of the internal carotid artery is developed. The artery is modelled as a two-layered non-linear elastic cylindrical membrane using a physiologically realistic constitutive model. It is subject to a constant systolic pressure and a physiological axial prestretch. The development of the aneurysm is assumed to be a consequence of the growth and remodelling of its material constituents. The elastinous constituents are prescribed to degrade in a localized circular patch. Microstructural recruitment and fibre concentration variables for the collagen fibres enable the growth and remodelling of collagen fabric to be simulated. The model predicts realistic saccular aneurysm geometries that stabilize in size. It provides the foundations for the development of more sophisticated models of cerebral aneurysm evolution.
Unified modelling in support of organization design and change
Authors: Rashid S , Masood T , Weston R H
Published: April 2009

The aim of this research is to provide a unified modelling-based method to help with the evaluation of organization design and change decisions. Relevant literature regarding model-driven organization design and change is described. This helps identify the requirements for a new modelling methodology. Such a methodology is developed and described. The three phases of the developed method include the following. First, the use of CIMOSA-based multi-perspective enterprise modelling to understand and capture the most enduring characteristics of process-oriented organizations and externalize various types of requirement knowledge about any target organization. Second, the use of causal loop diagrams to identify dynamic causal impacts and effects related to the issues and constraints on the organization under study. Third, the use of simulation modelling to quantify the effects of each issue in terms of organizational performance. The design and case study application of a unified modelling method based on CIMOSA (computer integrated manufacturing open systems architecture) enterprise modelling, causal loop diagrams, and simulation modelling, is explored to illustrate its potential to support systematic organization design and change. Further application of the proposed methodology in various company and industry sectors, especially in manufacturing sectors, would be helpful to illustrate complementary uses and relative benefits and drawbacks of the methodology in different types of organization. The proposed unified modelling-based method provides a systematic way of enabling key aspects of organization design and change. The case company, its relevant data, and developed models help to explore and validate the proposed method. The application of CIMOSA-based unified modelling method and integrated application of these three modelling techniques within a single solution space constitutes an advance on previous best practice. Also, the purpose and application domain of the proposed method offers an addition to knowledge.
Identification and reconstruction of surfaces based on distance function
Authors: Lou C , Zhu L , Ding H
Published: April 2009

This paper presents an approach for identification and reconstruction of surfaces from unorganized three-dimensional data. The concepts of distance function and free differential motion are introduced to characterize the kinematic properties of some kinds of surfaces, including simple surfaces and kinematic surfaces generated by a generatrix undergoing a screw motion. Then, a method is proposed automatically to identify the type of the surface and roughly estimate the location of the screw axis as well as the profile of the generatrix from the discrete measurement points. Based on the differential property of the signed distance function, a least-squares surface fitting algorithm is developed to finely tune the location and shape parameters of the reconstructed surface. This algorithm is also applicable to the reconstruction of implicit surfaces such as quadratic surfaces. Examples are provided to investigate the efficiency and precision of the developed method.
Fuzzy-neural-network-based fluctuation smoothing rule for reducing the cycle times of jobs with various priorities in a wafer fabrication plant: A simulation study
Authors: Chen T
Published: April 2009

This paper presents a fuzzy-neural-network-based fluctuation smoothing rule to further improve the performance of scheduling jobs with various priorities in a wafer fabrication plant. The fuzzy system is modified from the well-known fluctuation smoothing policy for a mean cycle time (FSMCT) rule with three innovative treatments. First, the remaining cycle time of a job is estimated by applying an existing fuzzy-neural-network-based approach to improve the estimation accuracy. Second, the components of the FSMCT rule are normalized to balance their importance. Finally, the division operator is applied instead of the traditional subtraction operator in order to magnify the difference in the slack and to enhance the responsiveness of the FSMCT rule. To evaluate the effectiveness of the proposed methodology, production simulation is applied to generate some test data. According to the experimental results, the proposed methodology outperforms six existing approaches in the reduction of the average cycle times. In addition, the new rule is shown to be a Pareto optimal solution for scheduling jobs in a semiconductor manufacturing plant.
The performance of polycrystalline cubic boron nitride tools in continuous, semi-interrupted, and interrupted hard machining
Authors: Halpin T , Byrne G , Barry J , Ahearne E
Published: April 2009

Polycrystalline cubic boron nitride (PCBN) cutting tools have enabled large-scale industrial hard machining owing to their high hot hardness and wear resistance. Experience clearly shows that tool requirements vary depending on the presence and severity of interrupts in the workpiece. The interrelationships between workpiece interruption parameters and tool wear and performance are assessed using a programme of continuous, semi-interrupted, and interrupted hard machining tests. A hypothesis for observed variations in wear behaviour between different PCBN grades and test conditions is developed on the basis of detailed tool wear scar analyses.
Dynamic analysis of functionally graded shell with piezoelectric layers based on elasticity
Authors: Javanbakht M , Shakeri M , Sadeghi S N
Published: April 2009

A study on the elasticity solution of the functionally graded (FG) shell with two piezoelectric layers is presented. In this article, the structure is finitely long, simply supported, and FG with two piezoelectric layers under pressure and electrostatic excitation. The equations of equilibrium, which are coupled partial differential equations, are reduced to ordinary differential equations (o.d.e.) with variable coefficients by means of trigonometric function expansion in the longitudinal direction. The resulting o.d.e. are solved by the Galerkin finite-element method and the Newmark method. Numerical results are presented for a FG cylindrical shell with a piezoelectric layer as an actuator in the external surface and a piezoelectric layer as a sensor in the internal surface.
A study of the geometric design and gas port of the claw-type rotor
Authors: Hsieh C-F
Published: April 2009

This article presents a simple mathematical model for the geometric design of a claw-type rotor. Based on the parameter design, the different claw shapes can be produced, and the design of gas ports and the fluid carryover will be discussed. Hence, a better design course will be proposed for the design of gas ports. Additionally, feasible design regions of the parameters are determined for avoiding the interference between two rotor profiles. Finally, the pumping efficiency will be estimated by the comparisons of carryover area and area efficiency in varied parameters designs. These results can indicate a better design course for the designer.
The kinematics and statics of manipulators
Authors: Zhao J-S , Lu W , Chu F , Feng Z-J
Published: April 2009

As the kinematics and statics play a very important role in determining the actuating inputs and the effective loads that the end-effector sustains, this article focuses on this issue and proposes an analytical process to study the forward and inverse kinematics and statics of spatial manipulators. As series manipulators and parallel manipulators show different features in kinematics and statics, this article discusses them separately. First, the forward and inverse velocity problems of the manipulator linkages are investigated with reciprocal screw theory. Then, the static balance conditions together with forward and inverse statics of the manipulator linkages are established through virtual power theory. In the kinematics analysis, the primary conditions for feasible motions of an end-effector are addressed through velocity screws. Illustrative examples indicate that the method proposed in this article can be used to guide the singularity identification, path planning, and feasible motion determination.
Inflow boundary condition for one-dimensional gas dynamics simulation code of internal combustion engine manifolds
Authors: Chalet D , Chesse P , Hetet J-F , Tauzia X
Published: May 2009

The modelling of pressure wave propagation into internal combustion engine manifolds implies the knowledge of multi-dimensional phenomena. However, computational times can be very important and this complex system requires reducing the order of the models. In the current paper, a new one-dimensional modelling of the inflow boundary conditions for a plain open end is proposed. This is obtained with the use of a computational fluid dynamics code and an experimental test bench under unsteady state conditions. Numerical and experimental analyses show that the pressure losses can be modelled with a coefficient that depends on the Mach number as well as geometrical parameters. Finally, numerical results are compared with experimental data in a shock tube application with an intake manifold of internal combustion engine. The code enhancements significantly improve flow calculations.
A new machine-vision-based approach for rapid dimensional inspection of an integrated circuit carrier tape
Authors: Chen S-H , Liao T-T , Chen C-T
Published: April 2009

This study presents a rapid and reliable machine vision technique for measuring the principal features of interest in an integrated circuit carrier tape, namely the diameters of the circular sprocket perforations and centre hole, the width of the carrier tape, and the width and length of the centre cavity. In performing the measurement process, the quality of the image acquisition process is enhanced by using two auxiliary light sources to suppress the effects of natural variations in the environmental lighting conditions. Having acquired the image using a charge coupled device (CCD) camera, the features of interest are separated from the background region of the image using a two-threshold algorithm based on the Otsu threshold selection method. The edge of each feature is then extracted from the binary image using the Canny edge detection method. The dimensions of the circular features are obtained by fitting four right-angle triangles within the periphery of the extracted circular edge and then computing the circle diameter by taking the mean of the hypotenuse values of the four triangles as computed using the Pythagorean theorem.
Time—frequency and time-scale analysis of Barkhausen noise signals
Authors: Padovese L R , Martin N , Millioz F
Published: May 2009

Carrying out information about the microstructure and stress behaviour of ferromagnetic steels, magnetic Barkhausen noise (MBN) has been used as a basis for effective non-destructive testing methods, opening new areas in industrial applications. One of the factors that determines the quality and reliability of the MBN analysis is the way information is extracted from the signal. Commonly, simple scalar parameters are used to characterize the information content, such as amplitude maxima and signal root mean square. This paper presents a new approach based on the time—frequency analysis. The experimental test case relates the use of MBN signals to characterize hardness gradients in a AISI4140 steel. To that purpose different time—frequency (TFR) and time-scale (TSR) representations such as the spectrogram, the Wigner-Ville distribution, the Capongram, the ARgram obtained from an AutoRegressive model, the scalogram, and the Mellingram obtained from a Mellin transform are assessed. It is shown that, due to nonstationary characteristics of the MBN, TFRs can provide a rich and new panorama of these signals. Extraction techniques of some time—frequency parameters are used to allow a diagnostic process. Comparison with results obtained by the classical method highlights the improvement on the diagnosis provided by the method proposed.
A smart sensing platform for the classification of ambulatory patterns
Authors: Elliott M T , Ma X , Brett P N
Published: April 2009

This paper describes an innovative sensing approach allowing capture, discrimination, and classification of transients automatically in gait. A walking platform is described, which offers an alternative design to that of standard force plates with advantages that include mechanical simplicity and less restriction on dimensions. The scope of the work is to investigate as an experiment the sensitivity of the distributive tactile sensing method with the potential to address flexibility on gait assessment, including patient targeting and the extension to a variety of ambulatory applications. Using infrared sensors to measure plate deflection, gait patterns are compared with stored templates using a pattern recognition algorithm. This information is input into a neural network to classify normal and affected walking events, with a classification accuracy of just under 90 per cent achieved. The system developed has potential applications in gait analysis and rehabilitation, whereby it can be used as a tool for early diagnosis of walking disorders or to determine changes between pre- and post-operative gait.
Prediction of micromotion initiation of an implanted femur under physiological loads and constraints using the finite element method
Authors: Andreaus U , Colloca M
Published: April 2009

In cementless total hip replacement surgery the conditions for micromotion initiation at the bone—stem interface and the role of stair climbing versus gait in promoting incipient slipping deserve attention. The goal of the present paper was to propose a finite element approach for analysing the structural behaviour of hip joint prostheses under physiological loadings and boundary conditions, which allows the prediction of micromotion initiation with low computational effort. In this paper, three-dimensional (3D) finite element analyses were performed of intact and implanted human femurs in order to address the above-mentioned problems. Accurate finite element models based on computed tomography images of a human femur were employed; tetrahedral elements were used to construct the models and the contact options of a full bond between the femoral bone and stem were also used. The shear strains at the contact between femoral bone and stem were evaluated. Two loading cases, namely walking and stair climbing, were applied to investigate the effect of different loading conditions on the shear strain patterns. Shear strains in the z direction can be reasonably considered a significant stimulus of slip initiation or fibrous tissue formation or both at the bone—stem interface, whereas shear strains in the x— y plane can be assumed to be a sensible measurement of the tendency to implant—bone micromotion under torsional loads. Comparisons with other studies are complicated by the difference in the methods and testing conditions used. If mobilization is to be initiated, rotational displacements at the interface should be sensible and significant parameters, i.e. the material, should be distorted to some extent. Thus, for a particular point on the bone—metal interface, the maximum shear strain in any direction within the interface plane will indicate the likelihood of slippage initiation at that point. The different femur states (intact and implanted) and loading conditions (walking and stair climbing) are compared. The stair-climbing loads resulted in the highest strains observed under any conditions, either intact or implanted.
A non-linear controller design for the evaporator of a heat recovery steam generator
Authors: Tahami F , Nademi H
Published: April 2009

This article addresses a combined approach of sliding mode control (SMC) with generalized predictive control (GPC) to achieve fluid temperature control in the evaporator of a heat recovery steam generator. The evaporator is modelled as a first-order plus dead time process. The model is developed using the experimental data obtained at an actual power plant. An output error identification algorithm is used to minimize the error between the model and the experiments in different operating conditions. A GPC method is exploited to optimize the sliding surface and the coefficients of the switching functions used in SMC. The proposed control schemes are evaluated by thorough simulation for performance and robustness against parameter variations and disturbances.
Active vibration suppression of non-linear beams using optimal dynamic inversion
Authors: Ali Sk F , Padhi R
Published: April 2009

Euler-Bernoulli beams are distributed parameter systems that are governed by a non-linear partial differential equation (PDE) of motion. This paper presents a vibration control approach for such beams that directly utilizes the non-linear PDE of motion, and hence, it is free from approximation errors (such as model reduction, linearization etc.). Two state feedback controllers are presented based on a newly developed optimal dynamic inversion technique which leads to closed-form solutions for the control variable. In one formulation a continuous controller structure is assumed in the spatial domain, whereas in the other approach it is assumed that the control force is applied through a finite number of discrete actuators located at predefined discrete locations in the spatial domain. An implicit finite difference technique with unconditional stability has been used to solve the PDE with control actions. Numerical simulation studies show that the beam vibration can effectively be decreased using either of the two formulations.
Novel multirate control strategy for piezoelectric actuators
Authors: Zareinejad M , Rezaei S M , Najafabadi H H , Ghidary S S , Abdullah A , Saadat M
Published: April 2009

In this article, a novel control method is proposed for feedforward compensation of hysteresis non-linearity in various frequency ranges. By integrating a multirate hysteresis compensator controller with PID feedback control, a combined controller is developed and experimentally validated for a piezoelectric micro-positioning system. Piezoelectric materials show non-linear hysteresis behaviour when they experience an electrical field. A fundamental study of a piezoelectric actuator (PEA) shows that the hysteresis effect deteriorates the tracking performance of the PEA. This paper presents a non-linear model which quantifies the hysteresis non-linearity generated in PEAs in response to the applied driving voltages. The tracking control method is based on multirate feedforward control. The proposed multirate control method uses an inverse modified Prandtl-Ishlinskii operator to cancel out hysteresis non-linearity. The controller structure has a simple design and can be quickly identified. The control system is capable of achieving suitable tracking control and it is convenient to use and can be quickly applied to practical PEA applications. Experimental results are provided to verify the efficiency of the proposed method.
Non-linear filter-based adaptive output feedback control for spacecraft formation flying
Authors: Shan J , Lin H
Published: April 2009

This paper presents a non-linear filter-based adaptive output control for spacecraft formation flying missions. The study is motivated by the fact that only accurate position measurements are available for some systems, and velocities have to be estimated from those measurements. The proposed adaptive output controller guarantees asymptotic stability of the position and velocity tracking motion, even in the presence of uncertainties and external perturbations. The effectiveness of the proposed controller is verified by numerical simulations.
Analyses of the stiffness and elastic deformation of a 2(3-SPR) serial—parallel manipulator
Authors: Lu Y , Hu B , Yu J
Published: May 2009

Stiffness is one of the important indices for evaluating the performances of serial—parallel manipulators (S—PMs), particularly when the S—PMs are used as machine tools and the robot arm/leg, and higher stiffness allows higher machining speed with higher accuracy of the end-effector. In this article, the stiffness and the elastic deformation of a 2(3-SPR) S—PM are studied systematically. First, a 2(3-SPR) S—PM, including an upper 3-SPR parallel manipulator (PM) and a lower 3-SPR PM, is constructed, and its characteristics are analysed. Second, some formulae for solving the elastic deformation and the compliance matrix of the active legs are derived from the available kinematics/statics of this S—PM. Third, based on the principle of virtual work and the compliance matrix of the active legs, the elastic deformation and the total stiffness matrix of this S—PM are solved and analysed.
Discrete Hit-and-Run for Sampling Points from Arbitrary Distributions Over Subsets of Integer Hyperrectangles
Authors: Baumert Stephen , Ghate Archis , Kiatsupaibul Seksan , Shen Yanfang , Smith Robert L. , Zabinsky Zelda B.
Published: April 2009

We consider the problem of sampling a point from an arbitrary distribution π over an arbitrary subset S of an integer hyperrectangle. Neither the distribution π nor the support set S are assumed to be available as explicit mathematical equations, but may only be defined through oracles and, in particular, computer programs. This problem commonly occurs in black-box discrete optimization as well as counting and estimation problems. The generality of this setting and high dimensionality of S precludes the application of conventional random variable generation methods. As a result, we turn to Markov chain Monte Carlo (MCMC) sampling, where we execute an ergodic Markov chain that converges to π so that the distribution of the point delivered after sufficiently many steps can be made arbitrarily close to π. Unfortunately, classical Markov chains, such as the nearest-neighbor random walk or the coordinate direction random walk, fail to converge to π because they can get trapped in isolated regions of the support set. To surmount this difficulty, we propose discrete hit-and-run (DHR), a Markov chain motivated by the hit-and-run algorithm known to be the most efficient method for sampling from log-concave distributions over convex bodies in Rn. We prove that the limiting distribution of DHR is π as desired, thus enabling us to sample approximately from π by delivering the last iterate of a sufficiently large number of iterations of DHR. In addition to this asymptotic analysis, we investigate finite-time behavior of DHR and present a variety of examples where DHR exhibits polynomial performance.