bluuebunny/crossref_metadata_2025 huggingface dataset:
LPS-induced cytokine production in human dendritic cells is regulated by sialidase activity
Authors: Stamatos Nicholas M , Carubelli Ivan , van de Vlekkert Diantha , Bonten Erik J , Papini Nadia , Feng Chiguang , Venerando Bruno , dˈAzzo Alessandra , Cross Alan S , Wang Lai-Xi , Gomatos Peter J
Published: September 2010

Neu1 and Neu3 are up-regulated as monocytes differentiate into DCs; and desialylation of cell surface glycoconjugates by one or both sialidase promotes cytokine production.

Removal of sialic acid from glycoconjugates on the surface of monocytes enhances their response to bacterial LPS. We tested the hypothesis that endogenous sialidase activity creates a permissive state for LPS-induced cytokine production in human monocyte-derived DCs. Of the four genetically distinct sialidases (Neu1–4), Neu1, Neu3, and Neu4 are expressed in human monocytes, but only Neu1 and Neu3 are up-regulated as cells differentiate into DCs. Neu1 and Neu3 are present on the surface of monocytes and DCs and are also present intracellularly. DCs contain a greater amount of sialic acid than monocytes, but the amount of sialic acid/mg total protein declines during differentiation to DCs. This relative hyposialylation of cells does not occur in mature DCs grown in the presence of zanamivir, a pharmacologic inhibitor of Neu3 but not Neu1, or DANA, an inhibitor of Neu1 and Neu3. Inhibition of sialidase activity during differentiation to DCs causes no detectable change in cell viability or expression of DC surface markers. Differentiation of monocytes into DCs in the presence of zanamivir results in reduced LPS- induced expression of IL-6, IL-12p40, and TNF-α by mature DCs, demonstrating a role for Neu3 in cytokine production. A role for Neu3 is supported by inhibition of cytokine production by DANA in DCs from Neu1–/– and WT mice. We conclude that sialidase-mediated change in sialic acid content of specific cell surface glycoconjugates in DCs regulates LPS-induced cytokine production, thereby contributing to development of adaptive immune responses.
Diet-Induced Obesity Causes Ghrelin Resistance in Arcuate NPY/AgRP Neurons
Authors: Briggs Dana I. , Enriori Pablo J. , Lemus Moyra B. , Cowley Michael A. , Andrews Zane B.
Published: September 2010

Circulating ghrelin is decreased in obesity, and peripheral ghrelin does not induce food intake in obese mice. We investigated whether ghrelin resistance was a centrally mediated phenomenon involving dysregulated neuropeptide Y (NPY) and agouti-related peptide (AgRP) circuits. We show that diet-induced obesity (DIO) (12 wk) suppresses the neuroendocrine ghrelin system by decreasing acylated and total plasma ghrelin, decreasing ghrelin and Goat mRNA in the stomach, and decreasing expression of hypothalamic GHSR. Peripheral (ip) or central (intracerebroventricular) ghrelin injection was able to induce food intake and arcuate nucleus Fos immunoreactivity in chow-fed but not high-fat diet-fed mice. DIO decreased expression of Npy and Agrp mRNA, and central ghrelin was unable to promote expression of these genes. Ghrelin did not induce AgRP or NPY secretion in hypothalamic explants from DIO mice. Injection of NPY intracerebroventricularly increased food intake in both chow-fed and high-fat diet-fed mice, indicating that downstream NPY/AgRP neural targets are intact and that defective NPY/AgRP function is a primary cause of ghrelin resistance. Ghrelin resistance in DIO is not confined to the NPY/AgRP neurons, because ghrelin did not stimulate growth hormone secretion in DIO mice. Collectively, our data suggests that DIO causes ghrelin resistance by reducing NPY/AgRP responsiveness to plasma ghrelin and suppressing the neuroendocrine ghrelin axis to limit further food intake. Ghrelin has a number of functions in the brain aside from appetite control, including cognitive function, mood regulation, and protecting against neurodegenerative diseases. Thus, central ghrelin resistance may potentiate obesity-related cognitive decline, and restoring ghrelin sensitivity may provide therapeutic outcomes for maintaining healthy aging.
Baseline Inhibin B and Anti-Mullerian Hormone Measurements for Diagnosis of Hypogonadotropic Hypogonadism (HH) in Boys with Delayed Puberty
Authors: Coutant Régis , Biette-Demeneix Estelle , Bouvattier Claire , Bouhours-Nouet Natacha , Gatelais Frédérique , Dufresne Sylvie , Rouleau Stéphanie , Lahlou Najiba
Published: September 2010

Context: The diagnosis of isolated hypogonadotropic hypogonadism (IHH) in boys with delayed puberty is challenging, as may be the diagnosis of hypogonadotropic hypogonadism (HH) in boys with combined pituitary hormone deficiency (CPHD). Yet, the therapeutic choices for puberty induction depend on accurate diagnosis and may influence future fertility.

Objective: The aim was to assess the utility of baseline inhibin B (INHB) and anti-Mullerian hormone (AMH) measurements to discriminate HH from constitutional delay of puberty (CDP). Both hormones are produced by Sertoli cells upon FSH stimulation. Moreover, prepubertal AMH levels are high as a reflection of Sertoli cell integrity.

Patients: We studied 82 boys aged 14 to 18 yr with pubertal delay: 16 had IHH, 15 congenital HH within CPHD, and 51 CDP, as confirmed by follow-up. Subjects were genital stage 1 (testis volume <3 ml; 9 IHH, 7 CPHD, and 23 CDP) or early stage 2 (testis volume, 3–6 ml; 7 IHH, 8 CPHD, and 28 CDP).

Results: Age and testis volume were similar in the three groups. Compared with CDP subjects, IHH and CPHD subjects had lower INHB, testosterone, FSH, and LH concentrations (P < 0.05), whereas AMH concentration was lower only in IHH and CPHD subjects with genital stage 1, likely reflecting a smaller pool of Sertoli cells in profound HH. In IHH and CPHD boys with genital stage 1, sensitivity and specificity were 100% for INHB concentration of 35 pg/ml or less. In IHH and CPHD boys with genital stage 2, sensitivities were 86 and 80%, whereas specificities were 92% and 88%, respectively, for an INHB concentration of 65 pg/ml or less. The performance of testosterone, AMH, FSH, and LH measurements was lower. No combination or ratio of hormones performed better than INHB alone.

Conclusion: Discrimination of HH from CDP with baseline INHB measurement was excellent in subjects with genital stage 1 and fair in subjects with genital stage 2.
Generation of distinct signaling modes via diversification of the Egfr ligand-processing cassette
Authors: Rousso Tal , Lynch Jeremy , Yogev Shaul , Roth Siegfried , Schejter Eyal D. , Shilo Ben-Zion
Published: September 2010

Egfr ligand processing in Drosophila involves trafficking of the ligand precursor by the chaperone Star from the endoplasmic reticulum (ER) to a secretory compartment, where the precursor is cleaved by the intramembrane protease Rhomboid. Some of the Drosophila Rhomboids also reside in the ER, where they attenuate signaling by premature cleavage of Star. The genome of the flour beetle Tribolium castaneum contains a single gene for each of the ligand-processing components, providing an opportunity to assess the regulation and impact of a simplified ligand-processing cassette. We find that the central features of ligand retention, trafficking by the chaperone and cleavage by Rhomboid have been conserved. The single Rhomboid is localized to both ER and secretory compartments. However, we show that Tribolium Star is refractive to Rhomboid cleavage. Consequently, this ligand-processing system effectively mediates long-range Egfr activation in the Tribolium embryonic ventral ectoderm, despite ER localization of Rhomboid. Diversification of the Egfr signaling pathway appears to have coupled gene duplication events with modulation of the biochemical properties and subcellular localization patterns of Rhomboid proteases and their substrates.
The absence ofPrep1causes p53-dependent apoptosis of mouse pluripotent epiblast cells
Authors: Fernandez-Diaz Luis C. , Laurent Audrey , Girasoli Sara , Turco Margherita , Longobardi Elena , Iotti Giorgio , Jenkins Nancy A. , Fiorenza Maria Teresa , Copeland Neal G. , Blasi Francesco
Published: September 2010

Disruption of mouse Prep1, which codes for a homeodomain transcription factor, leads to embryonic lethality during post-implantation stages. Prep1–/– embryos stop developing after implantation and before anterior visceral endoderm (AVE) formation. In Prep1–/– embryos at E6.5 (onset of gastrulation), the AVE is absent and the proliferating extra-embryonic ectoderm and epiblast, marked by Bmp4 and Oct4, respectively, are reduced in size. At E.7.5, Prep1–/– embryos are small and very delayed, showing no evidence of primitive streak or of differentiated embryonic lineages. Bmp4 is expressed residually, while the reduced number of Oct4-positive cells is constant up to E8.5. At E6.5, Prep1–/– embryos retain a normal mitotic index but show a major increase in cleaved caspase 3 and TUNEL staining, indicating apoptosis. Therefore, the mouse embryo requires Prep1 when undergoing maximal expansion in cell number. Indeed, the phenotype is partially rescued in a p53–/–, but not in a p16–/–, background. Apoptosis is probably due to DNA damage as Atm downregulation exacerbates the phenotype. Despite this early lethal phenotype, Prep1 is not essential for ES cell establishment. A differential embryonic expression pattern underscores the unique function of Prep1 within the Meis-Prep family.
A role for PDGF signaling in expansion of the extra-embryonic endoderm lineage of the mouse blastocyst
Authors: Artus Jérôme , Panthier Jean-Jacques , Hadjantonakis Anna-Katerina
Published: September 2010

The inner cell mass (ICM) of the implanting mammalian blastocyst comprises two lineages: the pluripotent epiblast (EPI) and primitive endoderm (PrE). We have identified platelet-derived growth factor receptor alpha (PDGFRα) as an early marker of the PrE lineage and its derivatives in both mouse embryos and ex vivo paradigms of extra-embryonic endoderm (ExEn). By combining live imaging of embryos and embryo-derived stem cells expressing a histone H2B-GFP fusion reporter under the control of Pdgfra regulatory elements with the analysis of lineage-specific markers, we found that Pdgfra expression coincides with that of GATA6, the earliest expressed transcriptional regulator of the PrE lineage. We show that GATA6 is required for the activation of Pdgfra expression. Using pharmacological inhibition and genetic inactivation we addressed the role of the PDGF pathway in the PrE lineage. Our results demonstrate that PDGF signaling is essential for the establishment, and plays a role in the proliferation, of XEN cells, which are isolated from mouse blastocyst stage embryos and represent the PrE lineage. Implanting Pdgfra mutant blastocysts exhibited a reduced number of PrE cells, an effect that was exacerbated by delaying implantation. Surprisingly, we also noted an increase in the number of EPI cells in implantation-delayed Pdgfra-null mutants. Taken together, our data suggest a role for PDGF signaling in the expansion of the ExEn lineage. Our observations also uncover a possible role for the PrE in regulating the size of the pluripotent EPI compartment.
Preaxial polydactyly: interactions among ETV, TWIST1 and HAND2 control anterior-posterior patterning of the limb
Authors: Zhang Zhen , Sui Pengfei , Dong Aiwu , Hassell John , Cserjesi Peter , Chen You-Tzung , Behringer Richard R. , Sun Xin
Published: September 2010

Preaxial polydactyly (PPD) is a common limb-associated birth defect characterized by extra digit(s) in the anterior autopod. It often results from ectopic sonic hedgehog (Shh) expression in the anterior limb bud. Although several transcription factors are known to restrict Shh expression to the posterior limb bud, how they function together remains unclear. Here we provide evidence from mouse conditional knockout limb buds that the bHLH family transcription factor gene Twist1 is required to inhibit Shh expression in the anterior limb bud mesenchyme. More importantly, we uncovered genetic synergism between Twist1 and the ETS family transcription factor genes Etv4 and Etv5 (collectively Etv), which also inhibit Shh expression. Biochemical data suggest that this genetic interaction is a result of direct association between TWIST1 and ETV proteins. Previous studies have shown that TWIST1 functions by forming homodimers or heterodimers with other bHLH factors including HAND2, a key positive regulator of Shh expression. We found that the PPD phenotype observed in Etv mutants is suppressed by a mutation in Hand2, indicative of genetic antagonism. Furthermore, overexpression of ETV proteins influences the dimerization of these bHLH factors. Together, our data suggest that through biochemical interactions, the Shh expression regulators ETV, TWIST1 and HAND2 attain a precise balance to establish anterior-posterior patterning of the limb.
The Na+/H+ exchanger Nhx1p regulates the initiation of Saccharomyces cerevisiae vacuole fusion
Authors: Qiu Quan-Sheng , Fratti Rutilio A.
Published: September 2010

Nhx1p is a Na+(K+)/H+ antiporter localized at the vacuolar membrane of the yeast Saccharomyces cerevisiae. Nhx1p regulates the acidification of cytosol and vacuole lumen, and is involved in membrane traffic from late endosomes to the vacuole. Deletion of the gene leads to aberrant vacuolar morphology and defective vacuolar protein sorting. These phenotypes are hallmarks of malfunctioning vacuole homeostasis and indicate that membrane fusion is probably altered. Here, we investigated the role of Nhx1p in the regulation of homotypic vacuole fusion. Vacuoles isolated from nhx1Δ yeast showed attenuated fusion. Assays configured to differentiate between the first round of fusion and ongoing rounds showed that nhx1Δ vacuoles were only defective in the first round of fusion, suggesting that Nhx1p regulates an early step in the pathway. Although fusion was impaired on nhx1Δ vacuoles, SNARE complex formation was indistinguishable from wild-type vacuoles. Fusion could be rescued by adding the soluble SNARE Vam7p. However, Vam7p only activated the first round of nhx1Δ vacuole fusion. Once fusion was initiated, nhx1Δ vacuoles appeared behave in a wild-type manner. Complementation studies showed that ion transport function was required for Nhx1p-mediated support of fusion. In addition, the weak base chloroquine restored nhx1Δ fusion to wild-type levels. Together, these data indicate that Nhx1p regulates the initiation of fusion by controlling vacuole lumen pH.
Regulation of bile canalicular network formation and maintenance by AMP-activated protein kinase and LKB1
Authors: Fu Dong , Wakabayashi Yoshiyuki , Ido Yasuo , Lippincott-Schwartz Jennifer , Arias Irwin M.
Published: September 2010

AMP-activated protein kinase (AMPK), a cellular metabolic sensor, is essential in energy regulation and metabolism. Hepatocyte polarization during liver development and regeneration parallels increased metabolism. The current study investigates the effects of AMPK and its upstream activator LKB1 on polarity and bile canalicular network formation and maintenance in collagen sandwich cultures of rat hepatocytes. Immunostaining for the apical protein ABCB1 and the tight junction marker occludin demonstrated that canalicular network formation is sequential and is associated with activation of AMPK and LKB1. AMPK and LKB1 activators accelerated canalicular network formation. Inhibition of AMPK or LKB1 by dominant-negative AMPK or kinase-dead LKB1 constructs blocked canalicular network formation. AICAR and 2-deoxyglucose, which activate AMPK, circumvented the inhibitory effect of kinase-dead LKB1 on canalicular formation, indicating that AMPK directly affects canalicular network formation. After the canalicular network was formed, inhibition of AMPK and LKB1 by dominant-negative AMPK or kinase-dead LKB1 constructs resulted in loss of canalicular network, indicating that AMPK and LKB1 also participate in network maintenance. In addition, activation of AMPK and LKB1 prevented low-Ca2+-mediated disruption of the canalicular network and tight junctions. These studies reveal that AMPK and its upstream kinase, LKB1, regulate canalicular network formation and maintenance.
Pro-cathepsin D interacts with the extracellular domain of the β chain of LRP1 and promotes LRP1-dependent fibroblast outgrowth
Authors: Beaujouin Mélanie , Prébois Christine , Derocq Danielle , Laurent-Matha Valérie , Masson Olivier , Pattingre Sophie , Coopman Peter , Bettache Nadir , Grossfield Jami , Hollingsworth Robert E. , Zhang Hongyu , Yao Zemin , Hyman Bradley T. , van der Geer Peter , Smith Gary K. , Liaudet-Coopman Emmanuelle
Published: September 2010

Interactions between cancer cells and fibroblasts are crucial in cancer progression. We have previously shown that the aspartic protease cathepsin D (cath-D), a marker of poor prognosis in breast cancer that is overexpressed and highly secreted by breast cancer cells, triggers mouse embryonic fibroblast outgrowth via a paracrine loop. Here, we show the requirement of secreted cath-D for human mammary fibroblast outgrowth using a three-dimensional co-culture assay with breast cancer cells that do or do not secrete pro-cath-D. Interestingly, proteolytically-inactive pro-cath-D remains mitogenic, indicating a mechanism involving protein-protein interaction. We identify the low-density lipoprotein (LDL) receptor-related protein-1, LRP1, as a novel binding partner for pro-cath-D in fibroblasts. Pro-cath-D binds to residues 349–394 of the β chain of LRP1, and is the first ligand of the extracellular domain of LRP1β to be identified. We show that pro-cath-D interacts with LRP1β in cellulo. Interaction occurs at the cell surface, and overexpressed LRP1β directs pro-cath-D to the lipid rafts. Our results reveal that the ability of secreted pro-cath-D to promote human mammary fibroblast outgrowth depends on LRP1 expression, suggesting that pro-cath-D–LRP1β interaction plays a functional role in the outgrowth of fibroblasts. Overall, our findings strongly suggest that pro-cath-D secreted by epithelial cancer cells promotes fibroblast outgrowth in a paracrine LRP1-dependent manner in the breast tumor microenvironment.
WLS-dependent secretion of WNT3A requires Ser209 acylation and vacuolar acidification
Authors: Coombs Gary S. , Yu Jia , Canning Claire A. , Veltri Charles A. , Covey Tracy M. , Cheong Jit K. , Utomo Velani , Banerjee Nikhil , Zhang Zong Hong , Jadulco Raquel C. , Concepcion Gisela P. , Bugni Tim S. , Harper Mary Kay , Mihalek Ivana , Jones C. Michael , Ireland Chris M. , Virshup David M.
Published: September 2010

Wnt proteins are secreted post-translationally modified proteins that signal locally to regulate development and proliferation. The production of bioactive Wnts requires a number of dedicated factors in the secreting cell whose coordinated functions are not fully understood. A screen for small molecules identified inhibitors of vacuolar acidification as potent inhibitors of Wnt secretion. Inhibition of the V-ATPase or disruption of vacuolar pH gradients by diverse drugs potently inhibited Wnt/β-catenin signaling both in cultured human cells and in vivo, and impaired Wnt-regulated convergent extension movements in Xenopus embryos. WNT secretion requires its binding to the carrier protein wntless (WLS); we find that WLS is ER-resident in human cells and WNT3A binding to WLS requires PORCN-dependent lipid modification of WNT3A at serine 209. Inhibition of vacuolar acidification results in accumulation of the WNT3A–WLS complex both in cells and at the plasma membrane. Modeling predictions suggest that WLS has a lipid-binding β-barrel that is similar to the lipocalin-family fold. We propose that WLS binds Wnts in part through a lipid-binding domain, and that vacuolar acidification is required to release palmitoylated WNT3A from WLS in secretory vesicles, possibly to facilitate transfer of WNT3A to a soluble carrier protein.
Application of genetic algorithm to risk-based maintenance operations of liquefied natural gas carrier systems
Authors: Nwaoha T C , Yang Z , Wang J , Bonsall S
Published: September 2010

The concept of genetic algorithm (GA) is used to model the cost of maintenance and repair of a liquefied natural gas (LNG) containment system and its transfer arm, after assessing the total risk of the systems using the probabilistic risk assessment technique. The failure frequency data of the basic events of the fault tree developed to model the LNG containment system and transfer arm, which is implemented and evaluated to estimate the failure frequencies of the systems, are derived from a careful literature search. A total risk formula is developed, which is dependent on hazard severity weight, failure frequencies, and the time and cost of maintenance and repair of the LNG carrier systems. The formula serves as the objective function, while new total cost allocated for the maintenance and repair of the LNG carrier systems as a whole is the constraint with the boundaries of presenting initial/unit cost of maintenance and repair of each containment system and transfer arm. Optimization is carried out on the objective function and its constraint for the identification of new cost of maintaining and repairing the containment system and transfer arm independently with the powerful tool of GA using Matlab version 7.7 software for improvement of the system's safety level.
Heat generation/absorption effects on magnetohydrodynamic natural convection flow over a sphere in a non-Darcian porous medium
Authors: Moghimi M A , Talebizadeh P , Mehrabian M A
Published: September 2010

In this article, the magnetohydrodynamic natural convection boundary-layer flow on a sphere in a porous medium is studied numerically. The porous medium is saturated with an electrically conducting fluid and the fluid is subject to heat generation/absorption. A viscous flow model is presented using boundary-layer theory comprising the momentum and energy conservation equations. The governing boundary-layer equations are transformed into non-dimensional form using appropriate reference quantities. The resulting coupled non-linear system of partial differential equations is solved numerically using the differential quadrature method (DQM). The advantage of DQM, which was introduced as a promising method two decades ago, is that the solution is converged with a few grid points and hence the computational costs are reduced. Comparison is made between the results obtained by the DQM method and those obtained using the finite-difference method for the same operating conditions. A validation test is carried out for the case of infinite permeability (i.e. infinite Darcy number). The results of the present study were compared with the results of a similar investigation available in the literature. Close agreement between the two sets of results was noticed. A parametric study was performed in which the effect of various parameters on temperature and velocity fields, local Nusselt numbers, and wall friction coefficient were investigated.
Energy estimations for life-cycle analysis of jatropha, neem, and karanja biodiesels – a parametric study
Authors: Yadav A , Singh O
Published: September 2010

The present article deals with the study of environmental impacts of using biodiesels derived from jatropha, karanja, and neem tree using an energy life-cycle analysis approach. To evaluate the energy consumption during the life cycle of jatropha, karanja, and neem biodiesel as fuel for compression ignition (CI) engine, a cradle-to-grave analysis is carried out. Net energy ratio is calculated for each biodiesel by the ratio of the energy output of the system in the form of fuel energy delivered to the compression ignition engine and the cumulative energy demand of the system. Net energy ratios for jatropha, karanja, and neem biodiesel life cycles are R1 = 1.2325, R2 = 1.6425, and R3 = 1.6479, respectively. Life-cycle energy ratio of biodiesels shows that all the three fuels are renewable. It is concluded from the study that all biodiesels have higher output than inputs in terms of energy.
Rotating Heat Pipe Performance with Internal Wire Mesh Screens
Authors: Kamal M M , Amer I , Aboelnasr M
Published: September 2010

The performance of a rotating heat pipe was optimized in terms of the fluid charge ratio, speed of rotation, tapering angle together with relative positions, and the packing ratio of porous filling screens. The favourable effect of porous layers was testified by employing an inner liner along the whole tube interior surface to enhance both evaporation and condensation. The porosity effect was extended to include the whole pipe cross-section such that different configurations of screen layers packed together to form a turbulent extended heat transfer corrugated surface were investigated. It was found that the longitudinal temperature distribution along the heat pipe became more uniform as both the speed of rotation and the tapering angle increased, thus indicating a decrease in the heat pipe thermal resistance. Owing to the fact that enhanced evaporation and condensation take place, the overall heat transfer coefficient increased and the thermal capacity operational limits were extended by increasing the centrifugal acceleration within the stratified flow regime across the speed range of 0—700 r/min. The insertion of porous screens increased the rates of turbulent heat and mass transfer as well as the optimum charge ratio. By optimizing the porous configuration in terms of number of layers and bore size, the decrease in longitudinal temperature difference due to enhanced convection over-rode the increase in saturation temperature difference due to pressure drop. The increased fluid temperature uniformity in the core region, accompanied by severe radial temperature gradients close to the wall, thus revealed increased rates of convective heat transport.
Thermodynamic and Economic Analysis of Advanced and Externally Fired Gas Turbine Cycles
Authors: Ilett T , Lawn C J
Published: September 2010

The thermodynamic performance of a number of advanced gas turbine cycles and equivalent externally fired cycles has been studied to derive optimum efficiencies and work outputs. With external firing, significant improvements in the performance of the advanced cycles over the simple gas turbine cycle were found, demonstrating the potential of such cycles for effective power generation from biomass or other dirty fuels. Cost comparisons have been made and the minimum cost of electricity from each cycle calculated with discounted cash flow. The externally fired cycles benefit from low fuel costs which give favourable electricity costs, although development costs for the high-temperature heat exchanger and other advanced cycle components are likely to be significant. The gas—steam combined cycle when externally fired was found to give the lowest cost of electricity for large-scale generation, with the steam injected and humid air turbine cycles competitive on smaller scales.
Effect of scale-up of lower and middle splash region on heat transfer characteristics of circulating fluidized bed risers
Authors: Patil R S , Pandey M , Mahanta P
Published: September 2010

In the present work, a comparative study of steady-state wall-to-bed heat transfer was conducted along the lower and middle splash region located in the riser of height 2.85 m of three different circulating fluidized beds (CFBs) with bed cross-sections of 0.15 m×0.15 m, 0.20 m×0.20 m, and 0.25 m×0.25 m. Experiments were conducted under similar operating conditions on above-mentioned three CFB set-ups using the same weight of sand per unit area of the distributor plate, non-dimensional superficial velocity ( U∗), heat flux, and sand particle size. Further, experiments were conducted on all the three CFB set-ups for five different non-dimensional air velocities ( U∗ = 5, 5.5, 6, 6.6, and 8) and two different weights of sand inventory per unit area of the distributor plate with average particle size of 460 μm. Bed temperature distributions across the lower and middle splash regions were measured and compared for the three bed cross-sections. Axial distributions of heat transfer coefficient along the height of lower and middle splash region of risers were evaluated and compared for the three bed cross-sections. The effect of superficial velocity, sand inventory, and bed cross-section on temperature and heat transfer coefficient was investigated. Based on the present study, correlations were developed for the bed Nusselt number as a function of various non-dimensional numbers for lower and middle splash regions of the riser. The non-dimensional area parameter ( A∗) was found to be a significant number. Predictions of these correlations are in agreement (±16 per cent) with experimental data.
Using the Bees Algorithm with Kalman Filtering to Train an Artificial Neural Network for Pattern Classification
Authors: Pham D T , Darwish Haj A
Published: September 2010

The current paper presents the use of the bees algorithm with Kalman filtering to train a radial basis function (RBF) neural network. An enhanced fuzzy selection system has been developed to choose local search sites depending on the error and training accuracy of the RBF network. The paper provides comparative results obtained when applying RBF neural classifiers trained using the new bees algorithm, the original bees algorithm, and the conventional RBF procedure to an industrial pattern classification problem.
Fuzzy controller design for Takagi–Sugeno fuzzy models with multiplicative noises via relaxed non-quadratic stability analysis
Authors: Chang W-J , Chang C-H , Ku C-C
Published: September 2010

In this paper, a relaxed non-quadratic stabilization analysis is developed to design fuzzy controllers for non-linear stochastic systems that are constructed by the Takagi–Sugeno (T–S) fuzzy models with multiplicative noises. The multiplicative noise term is introduced in the consequent part of the T–S fuzzy system for representing the stochastic behaviour. According to the proposed T–S fuzzy models, a relaxed non-quadratic technique is employed to derive the stability conditions for closed-loop fuzzy control systems. The relaxed non-quadratic stability conditions developed in this paper lead to the linear matrix inequality (LMI) problem. By solving the proposed LMI problem, the feasible solutions of the fuzzy control gains can be obtained. Finally, two numerical simulations are given to demonstrate the usefulness and applicability of the proposed fuzzy controller design approach.
Non-fragile H∞ guaranteed cost controller design of uncertain non-linear stochastic neutral systems with distributed delays
Authors: Qiu J , Zhu X , Su L
Published: September 2010

This paper considers the non-fragile H∞ guaranteed cost control problem of uncertain non-linear stochastic neutral systems. Both distributed delays and dependent delays appear in these systems. The aim is to design a non-fragile H∞ guaranteed cost control law and to obtain the upper bound of the quadratic cost function. A robust H∞ stabilization condition is proposed based on the Lyapunov stability theory combined with the linear matrix inequalities (LMI) approach. Furthermore, a sufficient condition for the existence of the non-fragile H∞ guaranteed cost controller is presented by LMI. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed techniques.
Sonar sensor data processing based on optical flow in robot navigation
Authors: Park C W , Lee C Y
Published: September 2010

The application of optical flow techniques on artificial image sequences in computing relative motions of obstacles is studied as a data processing algorithm for ultrasonic sensors. These sensors in robot systems are widely used in calculating the distance of obstacles. However, owing to the angular uncertainty of sensor characteristics, limitations exist on the positioning of an object's location, making it difficult to obtain accurate velocity information. Collision avoidance in dynamic environments requires information on relative motion, such as distance and velocity. In this paper, a technique for image processing on a range of ultrasonic sensor data is suggested in order to obtain the relative motion of front objects. The proposed technique is conducted using a two-wheel differential drive robot for problem cases related to indoor navigation. Digital filtering is also conducted to smooth the fluctuations, after which relative velocity is calculated using the optical flow technique. Experimental results demonstrate the possible application of the proposed algorithm for robot navigation in dynamic environments. This technique will increase the intelligence of robot systems, allowing for effective sensing in various environmental conditions.
Cooperative robotic system for handling a geometrically unknown object
Authors: Monfaredi R , Rezaei S M , Talebi H A
Published: September 2010

The current paper presents a new approach for cooperative control of a robotic system for grasping and handling an object with unknown geometry. The robotic system consists of three Cartesian robots with three degrees of freedom. The unknown object is approximately represented by three two-degrees-of-freedom virtual links of unknown length. Considering each of the virtual links as part of the corresponding robot, three five-degrees-of-freedom robots result that coordinate with each other as a closed kinematic chain. To cope with the kinematic uncertainty of the object, an adaptive algorithm consisting of a kinematic adaptation law is developed herein.

For designing the controller, the dynamic equations of motion are transformed from joint space to the object space. In other words, the system dynamic is decoupled into a locked system and a shaped system. A proportional–derivative controller and a proportional–integral–derivative controller are developed for the shaped and locked systems, respectively.

The object is modelled in the SimMechanics toolbox of MATLAB, and the controllers are simulated in the Simulink environment. Simulation results show that the proposed kinematic adaptation law together with the control system gives good performance for the cooperative system.
Computational Fluid Dynamic Modelling a Heavy-Duty Compression-Ignition Engine Fuelled with Diesel and Gasoline-Like Fuels
Authors: Shi Y , Wang Y , Reitz R D
Published: September 2010

This paper presents a comprehensive investigation of a compression—ignition (CI) heavy-duty engine fuelled with diesel and gasoline-like fuels. A state-of-the-art engine computational fluid dynamics (CFD) tool was used to explore the influences of the physical and chemical properties of diesel and gasoline-like fuels (no. 91 gasoline and E10) on spray development, auto-ignition and combustion processes, and pollutant formation. The CFD simulation results were found to be consistent with available experimental measurements, both qualitatively and quantitatively. The results indicate that gasoline-like fuels are able to achieve better premixed charge in CI engines owing to their higher volatility and lower ignitability compared to diesel fuel, which promotes efficient, clean, and low temperature combustion. However, the high combustion pressure rise rate becomes problematic under some circumstances, especially for high octane number fuels, such as E10. Both previous experimental measurements and the present numerical results show that gasoline-like fuels have great potential to be used in future CI engines, but the injection strategies and injection system have to be optimized based on the fuel properties.
Effect of Two-Stage Injection on Unburned Hydrocarbon and Carbon Monoxide Emissions in Smokeless Low-Temperature Diesel Combustion with Ultra-High Exhaust Gas Recirculation
Authors: Li T , Suzuki M , Ogawa H
Published: September 2010

The unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions from smokeless low-temperature diesel combustion (LTC) with ultra-high exhaust gas recirculation (EGR) can be attributed to lowered combustion temperatures as well as to under-mixing of fuel-rich mixture along the combustion chamber walls, overly mixed fuel-lean mixture at the spray tails, and fuel missing the piston bowl and entering the squish zones. Two-stage injection has the potential to reduce UHC and CO emissions through decreasing the ratios of these mixtures. This study investigates the effects of two-stage fuel injection by varying the dwell between the two injections as well as the fuel quantity in each injection on the UHC and CO emissions, experimentally with a single-cylinder diesel engine. With the optimized dwell and injection ratio, two-stage injection can reduce the UHC and CO emissions, but these emissions are still at high levels in the ultra-high EGR smokeless LTC regime. Computational fluid dynamics simulations of the in-cylinder spray and mixture formation processes showed that with the two-stage injection, over-rich mixture in the squish zones can be significantly avoided but the over-lean mixtures at centre of the combustion chamber are little reduced, and these would likely be a significant source of UHC and CO emissions.
High-Speed Flow and Fuel Imaging Study of Available Spark Energy in a Spray-Guided Direct-Injection Engine and Implications on Misfires
Authors: Peterson B , Sick V
Published: September 2010

The spark energy transferred under the highly stratified conditions during late injection in a spray-guided spark-ignition direct-injection (SG-SIDI) engine is not well characterized. The impact of high pressures, temperatures, velocities, and variations in local fuel concentration along with temporal and/or spatial variations on spark performance must be better characterized. Previous spark ignition studies have not addressed the full range of conditions that are present in SG-SIDI engines. Therefore, high-speed particle image velocimetry (PIV) experiments are conducted to characterize the spark energy dependence for a wide range of well-defined homogeneous fuel—air equivalence ratios ( Φ = —2.9) and average air velocities (0—8 m/s) in an optical SG-SIDI engine. A moderate dependence of spark energy on equivalence ratio is shown to exist with average values of spark energy increasing by 21 per cent for the equivalence ratio range of Φ = —2.3. Air injection into the motored engine is used to prepare well-defined flow conditions without the complications of fuel concentration gradients that are present during fuel injection. This allows the study of the effects of velocity, shear strain rate, and vorticity on spark energy. The spark energy increases with velocity at the spark plug. This observation is consistent with findings reported in the literature for low-pressure conditions. A linear increase is shown between shear strain rate and spark energy, while vorticity and spark energy are only weakly correlated. Simultaneous high-speed PIV, planar laser-induced fluorescence, and spark-discharge electrical measurements are also performed in the optical SG-SIDI engine to measure flow properties and fuel concentrations under late injection. Operating parameters are chosen to be near peak indicated mean effective pressure performance, but they occasionally provide a random misfired or partial burned cycle. Misfired cycles occur under stoichiometric-to-lean mixtures and low velocities near the spark plug. The lower spark energies observed under these conditions are in agreement with the observations made under well-controlled mixture and flow conditions reported in this study. All mixture conditions found in misfiring and partially burning cycles are within the ignitability range and fall within the general population of all, predominantly well-burning, cycles. There is no predominant impact of shear strain rate and vorticity under late injection operation on misfires and partial burns.
Bayes linear kinematics in the analysis of failure rates and failure time distributions
Authors: Wilson K J , Farrow M
Published: September 2010

Collections of related Poisson or binomial counts arise, for example, from a number of different failures in similar machines or neighbouring time periods. A conventional Bayesian analysis requires a rather indirect prior specification and intensive numerical methods for posterior evaluations. An alternative approach using Bayes linear kinematics in which simple conjugate specifications for individual counts are linked through a Bayes linear belief structure is presented. Intensive numerical methods are not required. The use of transformations of the binomial and Poisson parameters is proposed. The approach is illustrated in two examples, one involving a Poisson count of failures, the other involving a binomial count in an analysis of failure times.
Review of recent advances in reliability of consecutive k-out-of-n and related systems
Authors: Eryilmaz S
Published: September 2010

This paper presents an overview of the research performed on reliability studies of consecutive k-out-of- n and related systems during the last decade. In particular, methods for reliability evaluation, importance and optimal arrangements of components, lifetime distribution, and stochastic orderings of such systems are presented, also research results on related systems are summarized.
Metal binding and substrate positioning by evolutionarily invariant U6 sequences in catalytically active protein-free snRNAs
Authors: Lee Caroline , Jaladat Yasaman , Mohammadi Afshin , Sharifi Armin , Geisler Sarah , Valadkhan Saba
Published: September 2010

We have previously shown that a base-paired complex formed by two of the spliceosomal RNA components, U6 and U2 small nuclear RNAs (snRNAs), can catalyze a two-step splicing reaction that depended on an evolutionarily invariant region in U6, the ACAGAGA box. Here we further analyze this RNA-catalyzed reaction and show that while the 5′ and 3′ splice site substrates are juxtaposed and positioned near the ACAGAGA sequence in U6, the role of the snRNAs in the reaction is beyond mere juxtaposition of the substrates and likely involves the formation of a sophisticated active site. Interestingly, the snRNA-catalyzed reaction is metal dependent, as is the case with other known splicing RNA enzymes, and terbium(III) cleavage reactions indicate metal binding by the U6/U2 complex within the evolutionarily conserved regions of U6. The above results, combined with the structural similarities between U6 and catalytically critical domains in group II self-splicing introns, suggest that the base-paired complex of U6 and U2 snRNAs is a vestigial ribozyme and a likely descendant of a group II-like self-splicing intron.
Strategyproof Approximation of the Minimax on Networks
Authors: Alon Noga , Feldman Michal , Procaccia Ariel D. , Tennenholtz Moshe
Published: September 2010

We consider the problem of locating a facility on a network represented by a graph. A set of strategic agents have different ideal locations for the facility; the cost of an agent is the distance between its ideal location and the facility. A mechanism maps the locations reported by the agents to the location of the facility. We wish to design mechanisms that are strategyproof (SP) in the sense that agents can never benefit by lying and, at the same time, provide a small approximation ratio with respect to the minimax measure. We design a novel “hybrid” strategyproof randomized mechanism that provides a tight approximation ratio of 3/2 when the network is a circle (known as a ring in the case of computer networks). Furthermore, we show that no randomized SP mechanism can provide an approximation ratio better than 2 - o(1), even when the network is a tree, thereby matching a trivial upper bound of two.
Two New Van Der Waerden Numbers: w(2; 3, 17) and w(2; 3, 18)
Authors: Ahmed Tanbir
Published: September 2010

The
On the Number of Certain Relatively Prime Subsets of {1, 2, . . . , n}
Authors: Tóth László
Published: September 2010

We give common generalizations of three formulae involving the number of relatively prime subsets of {1, 2, . . . ,
Powers of Sierpiński Numbers Base b
Authors: Caldwell Chris K. , Komatsu Takao
Published: September 2010

A Sierpiński number is a positive odd integer
On Relatively Prime Sets Counting Functions
Authors: Shonhiwa Temba
Published: September 2010

This work is motivated by Nathanson's recent paper on relatively prime sets and a phi function for subsets of {1, 2, 3, . . . ,
A note on pivotal Value-at-Risk estimates
Authors: Pflug Georg Ch. , Schaller Peter
Published: September 2010

Inspired by the practice of risk management in the financial industry, we introduce the notion of pivotal quantile estimates, and relate it to the theory of structural statistical models. This framework gives a mathematical foundation to unbiased estimation of exceedance probabilities. The application to Value at Risk calculations is illustrated by an operational risk example.
Empfindliches Messen partieller Kohärenz mit Pinhole-Array
Authors: Petruck Paul , Riesenberg Rainer , Kowarschik Richard
Published: September 2010

Interferometrische Mess- und Abbildungsverfahren sind häufig durch kohärentes Rauschen begrenzt. Eine Anpassung des Kohärenzvolumens an die Messbedingungen kann das Rauschen verringern. Für die holografische Mikroskopie müssen Kohärenzparameter im Mikrometerbereich eingestellt und gemessen werden. Das klassische Young´sche Doppelspalt-Interferometer ist dabei oft zu unempfindlich. Ein erweitertes Array-Interferometer liefert deutlich empfindlichere Messungen für die Bestimmung der Kohärenzfläche.
Verlässlichkeitsanalyse von Indikator-Funktionen in einem Automatisierten Multiskalen-Messsystem
Authors: Burla Avinash , Lyda Wolfram , Osten Wolfgang , Regin Johan , Westkämper Engelbert , Zimmermann Jan , Sawodny Oliver
Published: September 2010

Innerhalb automatisierter multiskaliger Messsysteme werden im Allgemeinen verschiedene Sensoren in verschiedenen Skalen zur Vermessung/Inspektion verwendet. Ausgehend von der niedrigstauflösenden Skale werden Indikationen für Defekte mittels Indikatoralgorithmen gefunden. Basierend auf diesen Defektindikationen werden Unterregionen für eine Vermessung mit höherer Auflösung spezifiziert. Dieser Vorgang wird iterativ bis zur klaren Defekterkennung durchgeführt. Grundlage einer entsprechenden Vorgehensweise ist die Verwendung zuverlässiger Indikatoralgorithmen. Entsprechende Algorithmen für die Vermessung von Mikrooptiken werden vorgestellt und hinsichtlich ihrer Zuverlässigkeit analysiert.
Digitale Mehrwellenlängen-Holografie für makroskopische Topografien in mikroskopischer Genauigkeit
Authors: Carl Daniel , Fratz Markus , Höfler Heinrich
Published: September 2010

Optische Systeme für die Vermessung dreidimensionaler Oberflächen sind für die Inline-Inspektion oft zu langsam oder zu ungenau. Deshalb hat Fraunhofer IPM Inspektionssysteme entwickelt, die auf digitaler Mehrwellenlängen-Holografie basieren. Die Systeme zeichnen sich durch extrem kurze Messzeit und hohe Genauigkeit aus und sind daher für die 100-Prozent-Kontrolle in der Fertigungslinie geeignet.