bluuebunny/crossref_metadata_2025 huggingface dataset:
A Pleiotrophin C-terminus peptide induces anti-cancer effects through RPTPβ/ζ
Authors: Diamantopoulou Zoi , Bermek Oya , Polykratis Apostolos , Hamma-Kourbali Yamina , Delbé Jean , Courty José , Katsoris Panagiotis
Published: September 2010

Background

Pleiotrophin, also known as HARP (Heparin Affin Regulatory Peptide) is a growth factor expressed in various tissues and cell lines. Pleiotrophin participates in multiple biological actions including the induction of cellular proliferation, migration and angiogenesis, and is involved in carcinogenesis. Recently, we identified and characterized several pleiotrophin proteolytic fragments with biological activities similar or opposite to that of pleiotrophin. Here, we investigated the biological actions of P(122-131), a synthetic peptide corresponding to the carboxy terminal region of this growth factor.

Results

Our results show that P(122-131) inhibits in vitro adhesion, anchorage-independent proliferation, and migration of DU145 and LNCaP cells, which express pleiotrophin and its receptor RPTPβ/ζ. In addition, P(122-131) inhibits angiogenesis in vivo, as determined by the chicken embryo CAM assay. Investigation of the transduction mechanisms revealed that P(122-131) reduces the phosphorylation levels of Src, Pten, Fak, and Erk1/2. Finally, P(122-131) not only interacts with RPTPβ/ζ, but also interferes with other pleiotrophin receptors, as demonstrated by selective knockdown of pleiotrophin or RPTPβ/ζ expression with the RNAi technology.

Conclusions

In conclusion, our results demonstrate that P(122-131) inhibits biological activities that are related to the induction of a transformed phenotype in PCa cells, by interacing with RPTPβ/ζ and interfering with other pleiotrophin receptors. Cumulatively, these results indicate that P(122-131) may be a potential anticancer agent, and they warrant further study of this peptide.
Prognostic significance and therapeutic implications of centromere protein F expression in human nasopharyngeal carcinoma
Authors: Cao Jing-Yan , Liu Li , Chen Shu-Peng , Zhang Xing , Mi Yan-Jun , Liu Zhi-Gang , Li Man-Zhi , Zhang Hua , Qian Chao-Nan , Shao Jian-Yong , Fu Li-Wu , Xia Yun-Fei , Zeng Mu-Sheng
Published: September 2010

Background

Our recent cDNA microarray data showed that centromere protein F (CENP-F) is significantly upregulated in primary cultured nasopharyngeal carcinoma (NPC) tumor cells compared with normal nasopharyngeal epithelial cells. The goal of this study was to further investigate the levels of CENP-F expression in NPC cell lines and tissues to clarify the clinical significance of CENP-F expression in NPC as well as the potential therapeutic implications of CENP-F expression.

Methods

Real-time RT-PCR and western blotting were used to examine CENP-F expression levels in normal primary nasopharyngeal epithelial cells (NPEC), immortalized nasopharyngeal epithelial cells and NPC cell lines. Levels of CENP-F mRNA were determined by real-time RT-PCR in 23 freshly frozen nasopharyngeal biopsy tissues, and CENP-F protein levels were detected by immunohistochemistry in paraffin sections of 202 archival NPC tissues. Statistical analyses were applied to test for prognostic associations. The cytotoxicities of CENP-F potential target chemicals, zoledronic acid (ZOL) and FTI-277 alone, or in combination with cisplatin, in NPC cells were determined by the MTT assay.

Results

The levels of CENP-F mRNA and protein were higher in NPC cell lines than in normal and immortalized NPECs. CENP-F mRNA level was upregulated in nasopharyngeal carcinoma biopsy tissues compared with noncancerous tissues. By immunohistochemical analysis, CENP-F was highly expressed in 98 (48.5%) of 202 NPC tissues. Statistical analysis showed that high expression of CENP-F was positively correlated with T classification (P< 0.001), clinical stage (P< 0.001), skull-base invasion (P< 0.001) and distant metastasis (P= 0.012) inversely correlated with the overall survival time in NPC patients. Multivariate analysis showed that CENP-F expression was an independent prognostic indicator for the survival of the patient. Moreover, we found that ZOL or FTI-277 could significantly enhance the chemotherapeutic sensitivity of NPC cell lines (HONE1 and 6-10B) with high CENP-F expression to cisplatin, although ZOL or FTI-277 alone only exhibited a minor inhibitory effect to NPC cells.

Conclusion

Our data suggest that CENP-F protein is a valuable marker of NPC progression, and CENP-F expression is associated with poor overall survival of patients. In addition, our data indicate a potential benefit of combining ZOL or FTI-277 with cisplatin in NPC suggesting that CENP-F expression may have therapeutic implications.
Cytostatic and anti-angiogenic effects of temsirolimus in refractory mantle cell lymphoma
Authors: Wang Li , Shi Wen-Yu , Wu Zhi-Yuan , Varna Mariana , Wang Ai-Hua , Zhou Li , Chen Li , Shen Zhi-Xiang , Lu He , Zhao Wei-Li , Janin Anne
Published: September 2010

Mantle cell lymphoma (MCL) is a rare and aggressive type of B-cell non-Hodgkin's lymphoma. Patients become progressively refractory to conventional chemotherapy, and their prognosis is poor. However, a 38% remission rate has been recently reported in refractory MCL treated with temsirolimus, a mTOR inhibitor.

Here we had the opportunity to study a case of refractory MCL who had tumor regression two months after temsirolimus treatment, and a progression-free survival of 10 months. In this case, lymph node biopsies were performed before and six months after temsirolimus therapy. Comparison of the two biopsies showed that temsirolimus inhibited tumor cell proliferation through cell cycle arrest, but did not induce any change in the number of apoptotic tumor cells. Apart from this cytostatic effect, temsirolimus had an antiangiogenic effect with decrease of tumor microvessel density and of VEGF expression. Moreover, numerous patchy, well-limited fibrotic areas, compatible with post-necrotic tissue repair, were found after 6-month temsirolimus therapy. Thus, temsirolimus reduced tumor burden through associated cytostatic and anti-angiogenic effects.

This dual effect of temsirolimus on tumor tissue could contribute to its recently reported efficiency in refractory MCL resistant to conventional chemotherapy.
Antifibrotic Properties of Relaxin: In Vivo Mechanism of Action in Experimental Renal Tubulointerstitial Fibrosis
Authors: Hewitson Tim D. , Ho Wen Yang , Samuel Chrishan S.
Published: September 2010

This study examined the efficacy and in vivo mechanism of action of the antifibrotic hormone, relaxin, in a mouse model of unilateral ureteric obstruction (UUO). Kidney fibrosis was assessed in recombinant human gene-2 relaxin-treated animals maintained for 3 and 9 d after UUO. Results were compared with untreated and unoperated animals (d 0). Total collagen, collagen subtypes (I, IV), TGF-β2 production, mothers against decapentaplegic homolog 2 (Smad2) phosphorylation, myofibroblast differentiation, mitosis, and apoptosis were all progressively increased by UUO (all P < 0.05 vs. d 0 group at d 3 and d 9), whereas TGF-β1 production was increased and vascular endothelial growth factor expression (angiogenesis) decreased at d 9 (both P < 0.05 vs. d 0). A progressive increase in matrix metalloproteinase (MMP)-2 after UUO suggested that it was reactive to the increased fibrogenesis. Conversely, MMP-9 was decreased at d 9, whereas its inhibitor tissue inhibitor of metalloproteinase-1 progressively decreased after UUO. Human gene-2 relaxin pretreatment of animals from 4 d prior to UUO ameliorated the increase in total collagen, collagen IV, Smad2 phosphorylation, and myofibroblasts at both time points (all P < 0.05 vs. untreated groups) and inhibited TGF-β2 production and cell proliferation (both P < 0.05 vs. untreated groups) with a trend toward normalizing vascular endothelial growth factor expression at d 9, with no effect on TGF-β1 production or apoptosis. The relaxin-mediated regulation of MMPs and tissue inhibitor of metalloproteinases in this model was not consistent with its antifibrotic properties. The beneficial effects of relaxin were lost when treatment was stopped. These findings establish that relaxin can inhibit both early and established phases of tubulointerstitial fibrosis, primarily by suppressing cell proliferation, myofibroblast differentiation, and collagen production. Not all of these effects paralleled changes to TGF-β-Smad signaling.
N-Glycosylation Increases the Circulatory Half-Life of Human Growth Hormone
Authors: Flintegaard Thomas V. , Thygesen Peter , Rahbek-Nielsen Henrik , Levery Steven B. , Kristensen Claus , Clausen Henrik , Bolt Gert
Published: September 2010

Therapeutic use of recombinant GH typically involves daily sc injections. We examined the possibilities for prolonging the in vivo circulation of GH by introducing N-glycans. Human GH variants with a single potential N-glycosylation site (N-X-S/T) introduced by site-directed mutagenesis were expressed in HEK293 cells. In a scan of 15 different positions for N-glycosylation sites, four positions (amino acids 93, 98, 99, and 101) were efficiently utilized and did not influence GH in vitro activity. A GH variant (3N-GH) with all these sites was produced in CHOK1SV cells and contained up to three N-glycans. Two pools of 3N-GH were purified and separated according to their charge by anion-exchange chromatography. Anion-exchange HPLC revealed that the N-glycans in the two pools were very similar except for the extent of sialylation. Both 3N-GH pools circulated longer in rats than wild-type GH. The terminal half-life of 3N-GH after iv injection was 24-fold prolonged compared with wild-type GH for the pool with the most pronounced sialylation, 13-fold prolonged for the less sialylated pool, and similar to the wild-type for desialylated 3N-GH. The less sialylated 3N-GH pool exhibited a profound pharmacodynamic effect in GH-deficient rats. Over a 4-d period, a single injection of 3N-GH induced a stronger IGF-I response and a larger increase in body weight than daily injections with wild-type GH. Thus, N-glycans can prolong the in vivo circulation and enhance the pharmacodynamic effect of GH. Sialic acids seem to play a pivotal role for the properties of glycosylated GH.
Functional Consequences of Dual Oxidase-Thyroperoxidase Interaction at the Plasma Membrane
Authors: Fortunato Rodrigo Soares , Lima de Souza Elaine Cristina , Hassani Rabii Ameziane-el , Boufraqech Myriem , Weyemi Urbain , Talbot Monique , Lagente-Chevallier Odile , de Carvalho Denise Pires , Bidart Jean-Michel , Schlumberger Martin , Dupuy Corinne
Published: September 2010

Context: Thyroperoxidase (TPO) and dual oxidase (DUOX) are present at the apical membrane of thyrocytes, where TPO catalyzes thyroid hormone biosynthesis in the presence of H2O2 produced by DUOX. Both enzymes are colocalized and associated, but the consequences of this interaction remain obscure.

Objective: The objective of this study was to evaluate the functional consequences of TPO-DUOX interaction at the plasma membrane.

Design: The functional consequences of DUOX-TPO interaction were studied by measuring extracellular H2O2 concentration and TPO activity in a heterologous system. For this purpose, HEK293 cells were transiently transfected with a combination of human TPO with human DUOX1 or DUOX2 in the presence of their respective maturation factors, DUOXA1 or DUOXA2. The effect of human DUOX2 mutants in which cysteine residues in the N-terminal domain were replaced by glycines was also analyzed.

Results: We observed that production of H2O2 decreases both TPO and DUOX activities. We show that TPO presents a catalase-like effect that protects DUOX from inhibition by H2O2. This catalase-like effect depends on the association between both enzymes, which probably occurs through the DUOX peroxidase-like domain because this effect was not observed with human DUOX2 mutants.

Conclusion: The DUOX-TPO association at the plasma membrane is relevant for normal enzyme properties. Normally, TPO consumes H2O2 produced by DUOX, decreasing the availability of this substance at the apical membrane of thyrocytes and, in turn, probably decreasing the oxidative damage of macromolecules.
Planar cell polarity: the orientation of larval denticles in Drosophila appears to depend on gradients of Dachsous and Fat
Authors: Repiso Ada , Saavedra Pedro , Casal José , Lawrence Peter A.
Published: September 2010

The larval ventral belts of Drosophila consist of six to seven rows of denticles that are oriented, some pointing forwards, some backwards. We present evidence that denticle orientation is determined almost entirely by Dachsous and Fat, one of two planar cell polarity systems. If we change the distribution of Dachsous we can alter the polarity of denticles. We suggest that the orientation of the individual denticle rows, in both the anterior compartment (which mostly point backwards) and the posterior compartment (which point forwards), is determined by the opposing slopes of a Dachsous/Fat gradient. We show, by altering the concentration gradients of Dachsous during development, that we can change the polarity of the denticles made by larval cells as they progress between the first and third larval instars without mitosis.
Quantitative analyses link modulation of sonic hedgehog signaling to continuous variation in facial growth and shape
Authors: Young Nathan M. , Chong H. Jonathan , Hu Diane , Hallgrímsson Benedikt , Marcucio Ralph S.
Published: September 2010

Variation is an intrinsic feature of biological systems, yet developmental biology does not frequently address population-level phenomena. Sonic hedgehog (SHH) signaling activity in the vertebrate forebrain and face is thought to contribute to continuous variation in the morphology of the upper jaw, but despite its potential explanatory power, this idea has never been quantitatively assessed. Here, we test this hypothesis with an experimental design that is explicitly focused on the generation and measurement of variation in multivariate shape, tissue growth, cellular behavior and gene expression. We show that the majority of upper jaw shape variation can be explained by progressive changes in the spatial organization and mitotic activity of midfacial growth zones controlled by SHH signaling. In addition, nonlinearity between our treatment doses and phenotypic outcomes suggests that threshold effects in SHH signaling may play a role in variability in midfacial malformations such as holoprosencephaly (HPE). Together, these results provide novel insight into the generation of facial morphology, and demonstrate the value of quantifying variation for our understanding of development and disease.
zif-1translational repression defines a second, mutually exclusive OMA function in germline transcriptional repression
Authors: Guven-Ozkan Tugba , Robertson Scott M. , Nishi Yuichi , Lin Rueyling
Published: September 2010

Specification of primordial germ cells requires global repression of transcription. In C. elegans, primordial germ cells are generated through four rounds of asymmetric divisions, starting from the zygote P0, each producing a transcriptionally repressed germline blastomere (P1-P4). Repression in P2-P4 requires PIE-1, which is provided maternally in oocytes and segregated to all germline blastomeres. We have shown previously that OMA-1 and OMA-2 repress global transcription in P0 and P1 by sequestering TAF-4, an essential component of TFIID. Soon after the first mitotic cycle, OMA proteins undergo developmentally regulated degradation. Here, we show that OMA proteins also repress transcription in P2-P4 indirectly, through a completely different mechanism that operates in oocytes. OMA proteins bind to both the 3′ UTR of the zif-1 transcript and the eIF4E-binding protein, SPN-2, repressing translation of zif-1 mRNA in oocytes. zif-1 encodes the substrate-binding subunit of the E3 ligase for PIE-1 degradation. Inhibition of zif-1 translation in oocytes ensures high PIE-1 levels in oocytes and germline blastomeres. The two OMA protein functions are strictly regulated in both space and time by MBK-2, a kinase activated following fertilization. Phosphorylation by MBK-2 facilitates the binding of OMA proteins to TAF-4 and simultaneously inactivates their function in repressing zif-1 translation. Phosphorylation of OMA proteins displaces SPN-2 from the zif-1 3′ UTR, releasing translational repression. We propose that MBK-2 phosphorylation serves as a developmental switch, converting OMA proteins from specific translational repressors in oocytes to global transcriptional repressors in embryos, together effectively repressing transcription in all germline blastomeres.
The overexpression of the putative gut stem cell marker Musashi-1 induces tumorigenesis through Wnt and Notch activation
Authors: Rezza Amelie , Skah Seham , Roche Colette , Nadjar Julien , Samarut Jacques , Plateroti Michelina
Published: September 2010

The RNA-binding protein Musashi-1 (Msi1) has been proposed as a marker of intestinal epithelial stem cells. These cells are responsible for the continuous renewal of the intestinal epithelium. Although the function of Msi1 has been studied in several organs from different species and in mammalian cell lines, its function and molecular regulation in mouse intestinal epithelium progenitor cells are still undefined. We describe here that, in these cells, the expression of Msi1 is regulated by the canonical Wnt pathway, through a mechanism involving a functional Tcf/Lef binding site on its promoter. An in vitro study in intestinal epithelium primary cultures showed that Msi1 overexpression promotes progenitor proliferation and activates Wnt and Notch pathways. Moreover, Msi1-overexpressing cells exhibit tumorigenic properties in xenograft experiments. These data point to a positive feedback loop between Msi1 and Wnt in intestinal epithelial progenitors. They also suggest that Msi1 has oncogenic properties in these cells, probably through induction of both the Wnt and Notch pathways.
The role ofSchizosaccharomyces pombe dma1in spore formation during meiosis
Authors: Krapp Andrea , del Rosario Elena Cano , Simanis Viesturs
Published: September 2010

Meiosis is a specialised form of the cell cycle that gives rise to haploid gametes. In Schizosaccharomyces pombe, the products of meiosis are four spores, which are formed by encapsulation of the four meiosis II nuclei within the cytoplasm of the zygote produced by fusion of the mating cells. The S. pombe spindle pole body is remodelled during meiosis II and membrane vesicles are then recruited there to form the forespore membrane, which encapsulates the haploid nucleus to form a prespore. Spore wall material is then deposited, giving rise to the mature spore. The septation initiation network is required to coordinate cytokinesis and mitosis in the vegetative cycle and for spore formation in the meiotic cycle. We have investigated the role of the SIN regulator dma1p in meiosis; we find that although both meiotic divisions occur in the absence of dma1p, asci frequently contain fewer than four spores, which are larger than in wild-type meiosis. Our data indicate that dma1p acts in parallel to the leading-edge proteins and septins to assure proper formation for the forespore membrane. Dma1p also contributes to the temporal regulation of the abundance of the meiosis-specific SIN component mug27p.
The nonsense-mediated decay pathway maintains synapse architecture and synaptic vesicle cycle efficacy
Authors: Long A. Ashleigh , Mahapatra Cecon T. , Woodruff Elvin A. , Rohrbough Jeff , Leung Hung-Tat , Shino Shikoh , An Lingling , Doerge Rebecca W. , Metzstein Mark M. , Pak William L. , Broadie Kendal
Published: September 2010

A systematic Drosophila forward genetic screen for photoreceptor synaptic transmission mutants identified no-on-and-no-off transient C (nonC) based on loss of retinal synaptic responses to light stimulation. The cloned gene encodes phosphatidylinositol-3-kinase-like kinase (PIKK) Smg1, a regulatory kinase of the nonsense-mediated decay (NMD) pathway. The Smg proteins act in an mRNA quality control surveillance mechanism to selectively degrade transcripts containing premature stop codons, thereby preventing the translation of truncated proteins with dominant-negative or deleterious gain-of-function activities. At the neuromuscular junction (NMJ) synapse, an extended allelic series of Smg1 mutants show impaired structural architecture, with decreased terminal arbor size, branching and synaptic bouton number. Functionally, loss of Smg1 results in a ~50% reduction in basal neurotransmission strength, as well as progressive transmission fatigue and greatly impaired synaptic vesicle recycling during high-frequency stimulation. Mutation of other NMD pathways genes (Upf2 and Smg6) similarly impairs neurotransmission and synaptic vesicle cycling. These findings suggest that the NMD pathway acts to regulate proper mRNA translation to safeguard synapse morphology and maintain the efficacy of synaptic function.
Arg206 of SNAP-25 is essential for neuroexocytosis at the Drosophila melanogaster neuromuscular junction
Authors: Megighian Aram , Scorzeto Michele , Zanini Damiano , Pantano Sergio , Rigoni Michela , Benna Clara , Rossetto Ornella , Montecucco Cesare , Zordan Mauro
Published: September 2010

An analysis of SNAP-25 isoform sequences indicates that there is a highly conserved arginine residue (198 in vertebrates, 206 in the genus Drosophila) within the C-terminal region, which is cleaved by botulinum neurotoxin A, with consequent blockade of neuroexocytosis. The possibility that it may play an important role in the function of the neuroexocytosis machinery was tested at neuromuscular junctions of Drosophila melanogaster larvae expressing SNAP-25 in which Arg206 had been replaced by alanine. Electrophysiological recordings of spontaneous and evoked neurotransmitter release under different conditions as well as testing for the assembly of the SNARE complex indicate that this residue, which is at the P1′ position of the botulinum neurotoxin A cleavage site, plays an essential role in neuroexocytosis. Computer graphic modelling suggests that this arginine residue mediates protein–protein contacts within a rosette of SNARE complexes that assembles to mediate the fusion of synaptic vesicles with the presynaptic plasma membrane.
Transmembrane domains control exclusion of membrane proteins from clathrin-coated pits
Authors: Mercanti Valentina , Marchetti Anna , Lelong Emmanuelle , Perez Franck , Orci Lelio , Cosson Pierre
Published: September 2010

Efficient sorting of proteins is essential to allow transport between intracellular compartments while maintaining their specific composition. During endocytosis, membrane proteins can be concentrated in endocytic vesicles by specific interactions between their cytoplasmic domains and cytosolic coat proteins. It is, however, unclear whether they can be excluded from transport vesicles and what the determinants for this sorting could be. Here, we show that in the absence of cytosolic sorting signals, transmembrane domains control the access of surface proteins to endosomal compartments. They act in particular by determining the degree of exclusion of membrane proteins from endocytic clathrin-coated vesicles. When cytosolic endocytosis signals are present, it is the combination of cytosolic and transmembrane determinants that ultimately controls the efficiency with which a given transmembrane protein is endocytosed.
Novel Optimization Technique for Variation Propagation Control in An Aero-Engine Assembly
Authors: Yang Z , Hussain T , Popov A A , McWilliam S
Published: September 2010

This paper presents a novel optimization technique in straight-build assembly to control variation propagation. The optimization technique is developed by minimizing the eccentricity stage by stage in the assembly. The straight-build assembly model is derived from connective assembly models, easily expressing the part-to-part relationships. Any measurement error or process error in the assembly can be easily incorporated in the model. This approach can be also used to predict the final assembly quality while the design is still at the conceptual stage. The straight-build assembly is validated by using statistical analysis through two case studies: a simple identical cylindrical-component assembly and a practical non-identical cylindrical-component assembly. The variation propagation can be reduced significantly for the straight-build assembly, compared to the direct-build assembly without optimization. The results show how the variation propagation control is related to process noise and measurement accuracy. The simulation results also show that minimal variation can be achieved at reduced cost by properly selecting the accuracy of measurement, according to process procedures. The information obtained provides a practical and useful approach for design engineers. The potential applications of the straight-build assembly are also illustrated.
Finite Element Analysis of the Roller Burnishing Process for Fatigue Resistance Increase of Engine Components
Authors: Klocke F , Bäcker V , Wegner H , Zimmermann M
Published: September 2010

Highly stressed components of modern aircraft engines, like turbine and compressor blades, have to satisfy stringent requirements regarding durability and reliability. The induction of compressive residual stresses and strain hardening in the surface layer of these components have been proved to be a very promising method to increase their fatigue resistance significantly. Previous research has shown that an improvement of these characteristics can lead to a slow-down of crack propagation or even complete crack closure due to shakedown effects. The required surface layer properties can be achieved by a number of different manufacturing processes, among which roller burnishing is distinguished by the following substantial advantages: high and deep-reaching compressive residual stresses, high strain hardening, and excellent surface quality. The determination of optimal process parameters in order to achieve a defined state of the surface layer still requires an elaborate experimental set-up and subsequent time-consuming and cost-extensive measurements. Therefore, in this article a novel approach for the quantitative prediction of the induced residual stresses by the roller burnishing process is proposed using finite element analysis (FEA). The developed FE models were verified by comparison of the calculated residual stress state with experimental results of roller burnishing tests for different process parameters and materials. The influence of the induced compressive residual stresses and strain hardening on the materials’ fatigue behaviour was examined subsequently using low cycle fatigue (LCF) tests.
Evaluation Technique for Determining Wheel Performance in the Grinding of Aerospace Materials
Authors: da Silva E J , Oliveira J F G
Published: September 2010

Nickel-based super alloys are used in a variety of applications in which high-temperature strength and resistance to creep, corrosion, and oxidation are required, such as in aircraft gas turbines, combustion chambers, and automotive engine valves. The properties that make these materials suitable for these applications also make them difficult to grind. Grinding systems for such materials are often built around vitrified cBN (cubic boron nitride) wheels to realize maximum productivity and minimum cost per part. Conditions that yield the most economical combination of stock removal rate and wheel wear are key to the successful implementation of the grinding system. Identifying the transition point for excessive wheel wear is important. The aim of this study is to compare the performance of different cBN wheels when grinding difficult-to-grind (DTG) materials by determining the ‘wheel wear characteristic curve’, which correlates the G-ratio to the calculated tangential force per abrasive grain. With the proposed methodology, a threshold force per grit above which the wheel wear rate increases rapidly can be quickly identified. A comparison of performance for two abrasive product formulations in the grinding of three materials is presented. The obtained results can be applied for the development of grinding applications for DTG materials.
Energy Conversion and Storage Potential of Photogalvanic Cell Based on Ethylenediaminetetraacetic Acid—New Methylene Blue plus Fast Green
Authors: Yadav S , Lal C
Published: September 2010

A mixed dyes system containing new methylene blue and fast green as a photosensitizer in photogalvanic cell has been studied for improved solar energy conversion and storage in the present work. Ethylenediaminetetraacetic acid has been used as an electron donor. The photopotential and photocurrent generated by the cell were measured to be 738.0 mV and 120.0 μA, respectively. The effect of various parameters such as pH, reductant concentration, dye concentration, diffusion length, and electrode area on the electrical output of the cell has been studied. The observed conversion efficiency was 0.564 per cent and the maximum output (power) of cell was 88.5 μW. The photogalvanic cell can be used in the dark at its power point for 90.0 min. The current—voltage ( i— V) characteristics of the cell have been studied, and a mechanism for the generation of photocurrent has also been proposed.
Robustly Optimal Wind Turbine for Swirl Expansion and Decay
Authors: Farthing S P
Published: September 2010

The wind turbine optima of propeller actuator disc theories are problematic. The large optimal windmill interference doubles the wake area from the vortex cylinder used to justify the propeller blade element momentum (BEM) theory. The general momentum (GM) theory incorporates expansion, but its optimum windrotor power blows up below a tip speed ratio of about unity where the BEM and experimental optima are low. Even without expansion, the GM and vortex theory optimum can still affect infinitely more gross power flux than in undisturbed wind. The inner massive swirl of their optimal wake is unstable or unrealizable by many indicators.

Rather than a cylindrical wake, the BEM is better founded on negligible suction from low swirl in a predominately axial wake expanded after instability and bursting of the hub vorticity outwards to cancel the axial component of the tip vorticity. If moderate swirl at outer high speed ratios can expand first with pressure regain, the optimum local power refines up to 5 per cent higher. Then only as this expanded outer axial vorticity is finally cancelled to relieve the suction from the swirl does the inner BEM flow slow and expand. The inner and outer axial velocities are equal with no radial velocity at local speed ratio 0.57 in the optimal rotor. Direct experimental verification of this dissipated expanded swirl head (DESH) refinement of the BEM is proposed further to support from measurements and computations in the literature. The design blade chord and pitch that make the DESH optimum robust to small changes in windspeed are little changed from the time-proven BEM design, whereas the GM robust chord has a singularity.
General path-following manoeuvres for an underwater vehicle using robust control synthesis
Authors: You S-S , Lim T-W , Jeong S-K
Published: September 2010

The current paper presents the robust autopilot controller design of an autonomous underwater vehicle (AUV) for path-tracking manoeuvres. First, an AUV dynamic model is established without external disturbances. Next, the control synthesis includes the H∞loop-shaping design, incorporating co-prime factorization perturbations. Then the autopilot controller is reduced to a reasonable order. In addition, the resulting control system has been evaluated extensively in both the frequency and the time domains. Finally, it is found that the proposed vehicle system provides good manoeuvrability over a wide range of operating conditions, even under model uncertainties.
Finite-time H∞ filtering of time-delay stochastic jump systems with unbiased estimation
Authors: He S , Liu F
Published: September 2010

This paper is concerned with the problem of unbiased stochastic finite-time H∞ filtering for a class of Markov jump systems with constant time-delays. The filtering error dynamics is constructed based on an H∞ filter with unbiased estimation condition. The objective is to design such an unbiased filter that the finite-time L2 gain from the unknown input to an estimation error is minimized or guaranteed to be less than or equal to a prescribed value. By using the stochastic Lyapunov–Krasovskii functional approach, sufficient conditions are obtained for the existence of the desired unbiased H∞ filter, which also guarantees the stochastic finite-time boundedness of the filtering error dynamic systems. The design criteria are presented in the form of linear matrix inequalities and described as the optimization algorithms. Finally, two numerical examples are employed to illustrate the effectiveness of the developed techniques.
Trajectory tracking control of a piezoelectric stage for dynamic load applications
Authors: Sofla M S , Rezaei S M , Zareinejad M , Saadat M
Published: September 2010

In this paper, a robust control approach using a novel hysteresis observer is developed for precise tracking control of piezoelectric actuators (PEAs). This control methodology considers the problems of unknown or uncertain system parameters, hysteresis non-linearity, and external load disturbances. For representing the behaviour of a PEA, a Bouc–Wen hysteresis model is integrated with a second-order linear dynamic. It is shown that the non-linear response of the model owing to the hysteresis effect acts as a bounded disturbance. Based on this fact a hysteresis observer is proposed to estimate the hysteresis effect. Then for real-time compensation of the observer error, parametric uncertainties, and external disturbances, a sliding mode control strategy with a perturbation estimation function is utilized. By using the proposed control approach the asymptotical stability in displacement tracking and robustness to the dynamic load disturbance can be provided. Finally, the proposed approach and conventional controllers are compared by experiments.
Improvement of Diesel Engine Performance by Variable Valve Train System
Authors: Tomoda T , Ogawa T , Ohki H , Kogo T , Nakatani K , Hashimoto E
Published: September 2010

The effects of variable valve timing and lift are studied in order to improve the thermal efficiency of a diesel engine, while maintaining low emission levels. At high load conditions, early closing of one of the intake valves or early intake valve opening realizes an enhancement of swirl intensity without increased pumping losses, and retarded intake valve closing reduces the effective compression ratio, both of which result in an increased exhaust gas recirculation ratio and an advanced fuel injection timing. Consequently low NO x formation and an improved thermal efficiency can be achieved simultaneously. At low load conditions, the injected fuel is dispersed in the cylinder by air swirl because of the small fuel quantity, and the increased effective compression ratio achieved by the early intake valve closing becomes effective at reducing hydrocarbon emissions. It is confirmed that the variable valve timing and lift system introduced in this research can flexibly change the engine parameters that govern engine combustion at various engine operating conditions. As a result, a 40 per cent reduction of engine-out NO x emissions and 4 per cent improvement of fuel consumption in the New European Driving Cycle (NEDC) are achieved. Furthermore, low-end torque could be increased by 40 per cent, utilizing exhaust pressure pulsation by matching of exhaust valve opening timing, and the overlap of intake and exhaust valve opening around top dead centre in the intake stroke. To enhance these benefits a new piston chamber with deep valve pockets is developed and its effect is investigated.
Extreme-value-model-based risk assessment for nuclear reactors
Authors: Scarrott C J , MacDonald A
Published: September 2010

The safety case for continuing operation of nuclear reactors requires reliable assessment of the likelihood of the coolant temperatures exiting the fuel channels exceeding certain critical levels. Temperature measurements are typically made at a fixed sample of fuel channels and used for reactor control. No sample measurements will exceed the predetermined control limit, whereas it is likely that some of the unobserved temperatures will exceed this limit. The challenge is to use the control measurements reliably to assess the risk of the critical temperature exceedance over all channels, while also accounting for the uncertainties in the risk estimation. A novel non-stationary extreme value mixture modelling technique is developed to provide rigorous extrapolation of the risk past the observed range of the sample data. The proposed technique builds upon previous deterministic and statistical approaches, while providing more accurate risk predictions with fuller account for uncertainties in the estimation. A spatial random effects model is used to capture the non-stationary spatial structure in the temperature variation across the reactor. Bayesian inference for the extreme value mixture model parameters is undertaken, which permits assessment of all sources of uncertainty including potential inclusion of expert prior information.
Distinct functions of maternal and somatic Pat1 protein paralogs
Authors: Marnef Aline , Maldonado Maria , Bugaut Anthony , Balasubramanian Shankar , Kress Michel , Weil Dominique , Standart Nancy
Published: September 2010

We previously identified Xenopus Pat1a (P100) as a member of the maternal CPEB RNP complex, whose components resemble those of P-(rocessing) bodies, and which is implicated in translational control in Xenopus oocytes. Database searches have identified Pat1a proteins in other vertebrates, as well as paralogous Pat1b proteins. Here we characterize Pat1 proteins, which have no readily discernable sequence features, in Xenopus oocytes, eggs, and early embryos and in human tissue culture cells. xPat1a and 1b have essentially mutually exclusive expression patterns in oogenesis and embryogenesis. xPat1a is degraded during meiotic maturation, via PEST-like regions, while xPat1b mRNA is translationally activated at GVBD by cytoplasmic polyadenylation. Pat1 proteins bind RNA in vitro, via a central domain, with a preference for G-rich sequences, including the NRAS 5′ UTR G-quadruplex-forming sequence. When tethered to reporter mRNA, both Pat proteins repress translation in oocytes. Indeed, both epitope-tagged proteins interact with the same components of the CPEB RNP complex, including CPEB, Xp54, eIF4E1b, Rap55B, and ePAB. However, examining endogenous protein interactions, we find that in oocytes only xPat1a is a bona fide component of the CPEB RNP, and that xPat1b resides in a separate large complex. In tissue culture cells, hPat1b localizes to P-bodies, while mPat1a-GFP is either found weakly in P-bodies or disperses P-bodies in a dominant-negative fashion. Altogether we conclude that Pat1a and Pat1b proteins have distinct functions, mediated in separate complexes. Pat1a is a translational repressor in oocytes in a CPEB-containing complex, and Pat1b is a component of P-bodies in somatic cells.
Distributions of the Kullback–Leibler divergence with applications
Authors: Belov Dmitry I. , Armstrong Ronald D.
Published: September 2010

The Kullback–Leibler divergence (KLD) is a widely used method for measuring the fit of two distributions. In general, the distribution of the KLD is unknown. Under reasonable assumptions, common in psychometrics, the distribution of the KLD is shown to be asymptotically distributed as a scaled (non‐central) chi‐square with one degree of freedom or a scaled (doubly non‐central) F. Applications of the KLD for detecting heterogeneous response data are discussed with particular emphasis on test security.
Security-Aspekte bei der Entwicklung eingebetteter Software
Authors: Adamczyk Heiko
Published: September 2010

Anforderungen an die Softwareentwicklung von funktional sicheren Geräten (Safety) werden in einschlägigen Normen bereits klar definiert. Dagegen gibt es bislang kaum vergleichbare Normen zur Abdeckung der IT-Sicherheit, die konkrete Anforderungen an die Software für das industrielle Umfeld liefert. Vor dem Anwendungshintergrund der industriellen Automatisierung wird dazu in diesem Beitrag das Konzept eines Frameworks vorgestellt, mit dessen Hilfe sicherheitskritische eingebettete Geräte unter Beachtung von IT-Security-Aspekten entwickeln werden können.
A renewal theoretic result in portfolio theory under transaction costs with multiple risky assets
Authors: Irle Albrecht , Prelle Claas
Published: September 2010

We consider a portfolio optimization problem in a Black-Scholes model with n stocks, in which an investor faces both fixed and proportional transaction costs. The performance of an investment strategy is measured by the average return of the corresponding portfolio over an infinite time horizon. At first, we derive a representation of the portfolio value process which only depends on the relative fractions of the total portfolio value that the investor holds in the different stocks. This representation allows us to consider these so-called risky fractions as the decision variables of the investor. We show a certain kind of stationarity (Harris recurrence) for a quite flexible class of strategies (constant boundary strategies). Then, using renewal theoretic methods, we are able to describe the asymptotic return by the behaviour of the risky fractions in a “typical” period between two trades. Our results generalize those of [irl1], who considered a financial market model with one bond and one stock, to a market with a finite number n>1 of stocks.
On the mean residual waiting time of records
Authors: Bdair Omar M. , Raqab Mohammad Z.
Published: September 2010

In this paper, we examine the mean residual waiting time of record values from a sequence of identically independent random variables with a common continuous distribution F. Under the condition that the (m+1)-st shock has not arrived by time t>0, we obtain a simplified expression for the mean residual waiting time of the (n+1)-st shock. We investigate some monotonicity and aging properties for the mean residual waiting time of records. Further, it is shown that the underlying distribution function F can be recovered via the functional relationships between the mean residual waiting times of records.
Laser-Doppler-Distanzsensor mit Phasenauswertung zur Messung von Position und Form rotierender Objekte
Authors: Günther Philipp , Pfister Thorsten , Büttner Lars , Czarske Jürgen
Published: September 2010

In diesem Beitrag wird ein neuartiger optischer Sensor vorgestellt, der die gleichzeitige Messung von axialer Position und tangentialer Geschwindigkeit einer sich bewegenden rauen Festkörperoberfläche ermöglicht. Dafür wird ein erweitertes Laser-Doppler-Velozimeter genutzt, bei dem zwei gegeneinander verkippte Interferenzstreifensysteme überlagert werden. Es wird eine Positionsauflösung von 280 nm an rauen Festkörperoberflächen erreicht. Im Gegensatz zu herkömmlichen Messtechniken, wie der Triangulation, ist diese Positionsauflösung unabhängig von der Geschwindigkeit des Messobjektes. Dadurch ermöglicht dieser Sensor die präzise Positions- und Formbestimmung von schnell drehenden Objekten.
Energieautarke Sensorik im Flugzeug
Authors: Bartholomé Kilian , Jägle Martin , Ebling Dirk G. , König Jan , Jacqot Alexandre , Böttner Harald
Published: September 2010

Der Einsatz energieautarker Sensorik bietet die Möglichkeit, wartungsfrei Sensoren über einen sehr langen Zeitraum an unzugänglichen Orten zu betreiben. Durch den Einsatz thermoelektrischer Generatoren wird die Verwendung energieautarker Systeme überall da ermöglicht, wo Temperaturgradienten mit wenigen Kelvin existieren. In diesem Artikel wird der Einsatz eines durch Thermogeneratoren versorgten energieautarken Systems für den Einsatz im Flugzeug vorgestellt und die Minimierung thermischer Widerstände als wesentlicher Punkt für eine maximale Leistungsausbeute diskutiert.
Terahertz-Wellen — ein neuer Spektralbereich für die industrielle Messtechnik
Authors: Ellrich Frank , Weinland Tristan , Klier Jens , Jonuscheit Joachim , Beigang René
Published: September 2010

Zwischen Radar und Infrarot liegen die so genannten Terahertz-Wellen mit Wellenlängen im Bereich zwischen 30 μm und 3 mm. Diese können mit Hilfe moderner optischer Methoden effizient erzeugt und empfindlich nachgewiesen werden. Die technische Nutzung der Strahlung eröffnet neue Möglichkeiten sowohl in der Grundlagenforschung als auch speziell in der industriellen Messtechnik. Die Entwicklung eines fasergekoppelten Terahertz-Messsystems ermöglicht den Einsatz in unterschiedlichen industriellen Anwendungen, die an ausgewählten Beispielen vorgestellt werden.
Discussion of large deep venous thrombosis in childhood, based on three case studies
Authors: Turai Réka , Molnár Klára , Kiss Erika , Szokó Márta , Bauer Zita , Simon Gábor
Published: September 2010

A mélyvénás trombózis 18 év alatt ritka megbetegedés, becsült adatok szerint Magyarországon évente 1/100 000 a gyakorisága. Gyermekkorban a végtagi lokalizáció a jellemző, elsősorban újszülött- és serdülőkorban fordul elő. Létrejöttében veleszületett és szerzett hajlamosító tényezők játszanak szerepet. Ritkasága ellenére is gondolnunk kell rá, mivel a diagnózis felállításában történő késlekedés életveszélyt jelenthet a lehetséges szövődmény (pulmonalis embolia), illetve a lokalizáció (központi idegrendszeri vénás sinusok) miatt. A részletes, pontos anamnézis segíthet a kórisme meghatározásában. A szerzők három serdülőkorú betegük kapcsán tekintik át a mélyvénás trombózis etiológiáját, örökletes és szerzett rizikótényezőit, valamint a diagnosztikus és terápiás lehetőségeket. A gyermekkori mélyvénás trombózis diagnosztikájának buktatói: ritkábban fordul elő, mint felnőtteknél, így nem mindig gondolnak rá, az alvadási laborparaméterek életkorfüggőek, valamint a képalkotó vizsgálatok nehezebben kivitelezhetők. Orv. Hetil., 2010, 38, 1545–1550.
Hepatitis C virus infection and hepatocarcinogenesis
Authors: Szalay Ferenc
Published: September 2010

Ma már bizonyított, hogy nemcsak a HBV-, hanem a HCV-infekció is krónikus hepatitist, májcirrhosist és hepatocellularis májrákot (HCC) okozhat. A hepatitis C-vírus is onkogén vírusnak minősül. A két különböző vírus által indukált májrák kialakulásának mechanizmusa több közös és számos eltérő sajátságot mutat. Mindkét esetben többnyire hosszú évekig, akár évtizedekig tartó krónikus gyulladás által okozott májcirrhosis talaján alakul ki a májrák. A HCV mint RNS-vírus nem épül be a májsejt genomjába, hanem különböző utakon indukálja a ráksejtek kialakulását, amelyek azután kontroll nélkül proliferálnak. Már a HCV felfedezése előtt felfigyeltek az akkor még non-A-non-B-nek (NANB) nevezett hepatitis és a májrák közötti kapcsolatra. A későbbi epidemiológiai jellegű tanulmányok ezt megerősítették. Számos közlés van azonban arról, hogy a HCC cirrhosis nélkül is kialakulhat HCV-fertőzött egyénekben. A pontos mechanizmus nem ismert, de több adat utal arra, hogy a vírus bizonyos proteinjei képesek onkogén folyamatot indukálni. A HCV-core gén több pontján találtak különbséget a cirrhosis nélküli és a cirrhosis talaján kialakult HCC-ben. Feltételezhető, hogy a vírus az endoplazmás reticulumstressz és az oxidatív stressz következményeként különböző jelátviteli utak és az onkogén útvonalak direkt aktiválása révén fejti ki karcinogén hatását. Újabb adatok szerint a HCV inzulinrezisztenciát okozó hatásának is szerepe lehet az onkogenezisben. A vírus által determinált faktorok mellett a gazdaszervezet reakciójának, a tumor elleni védekezőképesség csökkenésének is szerepe van a májrák kialakulásában. Klinikai szempontból fontos a HCV-infekcióban szenvedő betegek rendszeres ellenőrzése tumorkialakulás szempontjából. A monitorozás fő eszköze az ultrahangvizsgálat. Az AFP csak az esetek egy részében pozitív. A már kialakult és diagnosztizált májrák kezelési stratégiája nem tér el a többi májbetegségben kialakult májrákétól. Orv. Hetil., 2010, 38, 1524–1529.