bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and molecular characterization of recurrent genomic deletions on 7p12 in the IKZF1 gene in a large cohort of BCR-ABL1–positive acute lymphoblastic leukemia patients: on behalf of Gruppo Italiano Malattie Ematologiche dell'Adulto Acute Leukemia Working Party (GIMEMA AL WP)
Authors: Iacobucci Ilaria , Storlazzi Clelia Tiziana , Cilloni Daniela , Lonetti Annalisa , Ottaviani Emanuela , Soverini Simona , Astolfi Annalisa , Chiaretti Sabina , Vitale Antonella , Messa Francesca , Impera Luciana , Baldazzi Carmen , D'Addabbo Pietro , Papayannidis Cristina , Lonoce Angelo , Colarossi Sabrina , Vignetti Marco , Piccaluga Pier Paolo , Paolini Stefania , Russo Domenico , Pane Fabrizio , Saglio Giuseppe , Baccarani Michele , Foà Robin , Martinelli Giovanni
Published: July 2009

The BCR-ABL1 fusion gene defines the subgroup of acute lymphoblastic leukemia (ALL) with the worst clinical prognosis. To identify oncogenic lesions that combine with BCR-ABL1 to cause ALL, we used Affymetrix Genome-Wide Human SNP arrays (250K NspI and SNP 6.0), fluorescence in situ hybridization, and genomic polymerase chain reaction to study 106 cases of adult BCR-ABL1–positive ALL. The most frequent somatic copy number alteration was a focal deletion on 7p12 of IKZF1, which encodes the transcription factor Ikaros and was identified in 80 (75%) of 106 patients. Different patterns of deletions occurred, but the most frequent were those characterized by a loss of exons 4 through 7 (Δ4-7) and by removal of exons 2 through 7 (Δ2-7). A variable number of nucleotides (patient specific) were inserted at the conjunction and maintained with fidelity at the time of relapse. The extent of the Δ4-7 deletion correlated with the expression of a dominant-negative isoform with cytoplasmic localization and oncogenic activity, whereas the Δ2-7 deletion resulted in a transcript lacking the translation start site. The IKZF1 deletion also was identified in the progression of chronic myeloid leukemia to lymphoid blast crisis (66%) but never in myeloid blast crisis or chronic-phase chronic myeloid leukemia or in patients with acute myeloid leukemia. Known DNA sequences and structural features were mapped along the breakpoint cluster regions, including heptamer recombination signal sequences recognized by RAG enzymes during V(D)J recombination, suggesting that IKZF1 deletions could arise from aberrant RAG-mediated recombination.
A comparison of random forest and its Gini importance with standard chemometric methods for the feature selection and classification of spectral data
Authors: Menze Bjoern H , Kelm B Michael , Masuch Ralf , Himmelreich Uwe , Bachert Peter , Petrich Wolfgang , Hamprecht Fred A
Published: July 2009

Background

Regularized regression methods such as principal component or partial least squares regression perform well in learning tasks on high dimensional spectral data, but cannot explicitly eliminate irrelevant features. The random forest classifier with its associated Gini feature importance, on the other hand, allows for an explicit feature elimination, but may not be optimally adapted to spectral data due to the topology of its constituent classification trees which are based on orthogonal splits in feature space.

Results

We propose to combine the best of both approaches, and evaluated the joint use of a feature selection based on a recursive feature elimination using the Gini importance of random forests' together with regularized classification methods on spectral data sets from medical diagnostics, chemotaxonomy, biomedical analytics, food science, and synthetically modified spectral data. Here, a feature selection using the Gini feature importance with a regularized classification by discriminant partial least squares regression performed as well as or better than a filtering according to different univariate statistical tests, or using regression coefficients in a backward feature elimination. It outperformed the direct application of the random forest classifier, or the direct application of the regularized classifiers on the full set of features.

Conclusion

The Gini importance of the random forest provided superior means for measuring feature relevance on spectral data, but – on an optimal subset of features – the regularized classifiers might be preferable over the random forest classifier, in spite of their limitation to model linear dependencies only. A feature selection based on Gini importance, however, may precede a regularized linear classification to identify this optimal subset of features, and to earn a double benefit of both dimensionality reduction and the elimination of noise from the classification task.
Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study: research design and methodology
Authors: Badland Hannah M , Schofield Grant M , Witten Karen , Schluter Philip J , Mavoa Suzanne , Kearns Robin A , Hinckson Erica A , Oliver Melody , Kaiwai Hector , Jensen Victoria G , Ergler Christina , McGrath Leslie , McPhee Julia
Published: July 2009

Background

Built environment attributes are recognized as being important contributors to physical activity (PA) engagement and body size in adults and children. However, much of the existing research in this emergent public health field is hindered by methodological limitations, including: population and site homogeneity, reliance on self-report measures, aggregated measures of PA, and inadequate statistical modeling. As an integral component of multi-country collaborative research, the Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study seeks to overcome these limitations by determining the strengths of association between detailed measures of the neighborhood built environment with PA levels across multiple domains and body size measures in adults and children. This article outlines the research protocol developed for the URBAN Study.

Methods and design

The URBAN Study is a multi-centered, stratified, cross-sectional research design, collecting data across four New Zealand cities. Within each city, 12 neighborhoods were identified and selected for investigation based on higher or lower walkability and Māori demographic attributes. Neighborhoods were selected to ensure equal representation of these characteristics. Within each selected neighborhood, 42 households are being randomly selected and an adult and child (where possible) recruited into the study. Data collection includes: objective and self-reported PA engagement, neighborhood perceptions, demographics, and body size measures. The study was designed to recruit approximately 2,000 adults and 250 children into the project. Other aspects of the study include photovoice, which is a qualitative assessment of built environment features associated with PA engagement, an audit of the neighborhood streetscape environment, and an individualized neighborhood walkability profile centered on each participant's residential address. Multilevel modeling will be used to examine the individual-level and neighborhood-level relationships with PA engagement and body size.

Discussion

The URBAN Study is applying a novel scientifically robust research design to provide urgently needed epidemiological information regarding the associations between the built environment and health outcomes. The findings will contribute to a larger, international initiative in which similar neighborhood selection and PA measurement procedures are utilized across eight countries. Accordingly, this study directly addresses the international priority issues of increasing PA engagement and decreasing obesity levels.
Amyloidogenic determinants are usually not buried
Authors: Frousios Kimon K , Iconomidou Vassiliki A , Karletidi Carolina-Maria , Hamodrakas Stavros J
Published: July 2009

Background

Amyloidoses are a group of usually fatal diseases, probably caused by protein misfolding and subsequent aggregation into amyloid fibrillar deposits. The mechanisms involved in amyloid fibril formation are largely unknown and are the subject of current, intensive research. In an attempt to identify possible amyloidogenic regions in proteins for further experimental investigation, we have developed and present here a publicly available online tool that utilizes five different and independently published methods, to form a consensus prediction of amyloidogenic regions in proteins, using only protein primary structure data.

Results

It appears that the consensus prediction tool is slightly more objective than individual prediction methods alone and suggests several previously not identified amino acid stretches as potential amyloidogenic determinants, which (although several of them may be overpredictions) require further experimental studies. The tool is available at: http://biophysics.biol.uoa.gr/AMYLPRED. Utilizing molecular graphics programs, like O and PyMOL, as well as the algorithm DSSP, it was found that nearly all experimentally verified amyloidogenic determinants (short peptide stretches favouring aggregation and subsequent amyloid formation), and several predicted, with the aid of the tool AMYLPRED, but not experimentally verified amyloidogenic determinants, are located on the surface of the relevant amyloidogenic proteins. This finding may be important in efforts directed towards inhibiting amyloid fibril formation.

Conclusion

The most significant result of this work is the observation that virtually all, to date, experimentally determined amyloidogenic determinants and the majority of predicted, but not yet experimentally verified short amyloidogenic stretches, lie 'exposed' on the surface of the relevant amyloidogenic proteins, and also several of them have the ability to act as conformational 'switches'. Experiments, focused on these fragments, should be performed to test this idea.
Hsa-miR-222 Is Involved in Differentiation of Endometrial Stromal Cells in Vitro
Authors: Qian Kun , Hu Linli , Chen Hong , Li Haixia , Liu Na , Li Yufeng , Ai Jihui , Zhu Guijin , Tang Zhouping , Zhang Hanwang
Published: July 2009

Decidualization is a critical step during embryo implantation and characterized by the differentiation of endometrial stromal cells (ESCs) into decidual cells. Because miRNAs are important determinants of cellular fate specification, in this study, the miRNA expression in ESCs during in vitro decidualization was profiled by using a microarray. Significance analysis of microarrays revealed that 49 miRNA genes were differently (>2-fold) expressed between the noninduced ESCs and induced ESCs with a false discovery rate of 0. The expression variance of hsa-miR-222, 221, 143, 101, 30d, 30c, 181b, 27b, 29b, 507, and 23a was validated by using quantitative PCR (P < 0.05). Based on microRNA (miRNA) and mRNA expression variance and predicted target genes of miRNAs, a bioinformatic model of miRNAs controlling ESCs differentiation was formulated. Finally, we proved that down-regulation of has-miR-222 could decrease the number of cells in S phase during ESCs differentiation (P < 0.05). Antisense oligonucleotides of has-miR-222 could increase reporter gene expression by targeting the 3′ untranslated regions of CDKN1C/p57kip2 mRNAs as well as increase CDKN1C/p57kip2 protein levels (P < 0.05). In conclusion, our results suggest that a subset of miRNAs play a key role in gene reprogramming during ESCs decidualization and that hsa-miR-222 participates in ESC differentiation by regulating ESCs terminally withdrawing from the cell cycle.
Increased Mitogen-Activated Protein Kinase Kinase/Extracellularly Regulated Kinase Activity in Human Endometrial Stromal Fibroblasts of Women with Endometriosis Reduces 3′,5′-Cyclic Adenosine 5′-Monophosphate Inhibition of Cyclin D1
Authors: Velarde Michael C. , Aghajanova Lusine , Nezhat Camran R. , Giudice Linda C.
Published: July 2009

Endometriosis is characterized by endometrial tissue growth outside the uterus, due primarily to survival, proliferation, and neoangiogenesis of eutopic endometrial cells and fragments refluxed into the peritoneal cavity during menses. Although various signaling molecules, including cAMP, regulate endometrial proliferation, survival, and embryonic receptivity in endometrium of women without endometriosis, the exact molecular signaling pathways in endometrium of women with disease remain unclear. Given the persistence of a proliferative profile and differential expression of genes associated with the MAPK signaling cascade in early secretory endometrium of women with endometriosis, we hypothesized that ERK1/2 activity influences cAMP regulation of the cell cycle. Here, we demonstrate that 8-Br-cAMP inhibits bromodeoxyuridine incorporation and cyclin D1 (CCND1) expression in cultured human endometrial stromal fibroblasts (hESF) from women without but not with endometriosis. Incubation with serum-containing or serum-free medium resulted in higher phospho-ERK1/2 levels in hESF of women with vs. without disease, independent of 8-Br-cAMP treatment. The MAPK kinase-1/2 inhibitor, U0126, fully restored cAMP down-regulation of CCND1, but not cAMP up-regulation of IGFBP1, in hESF of women with vs. without endometriosis. Immunohistochemistry demonstrated the highest phospho-ERK1/2 in the late-secretory epithelial and stromal cells in women without disease, in contrast to intense immunostaining in early-secretory epithelial and stromal cells in those with disease. These findings suggest that increased activation of ERK1/2 in endometrial cells from women with endometriosis may be responsible for persistent proliferative changes in secretory-phase endometrium.
Mammalian Target of Rapamycin Is Activated in Association with Myometrial Proliferation during Pregnancy
Authors: Jaffer Shabana , Shynlova Oksana , Lye Stephen
Published: July 2009

The adaptive growth of the uterus during gestation involves gradual changes in cellular phenotypes from the early proliferative to the intermediate synthetic phase of cellular hypertrophy, ending in the final contractile/labour phenotype. The mammalian target of rapamycin (mTOR) signaling pathway regulates cell growth and proliferation in many tissues. We hypothesized that mTOR was a mediator of hormone-initiated myometrial hyperplasia during gestation. The protein expression and phosphorylation levels of mTOR, its upstream regulators [insulin receptor substrate-1, phosphoinositide-3-kinase (PI3K), Akt], and downstream effectors [S6-kinase-1 (S6K1) and eI4FE-binding protein 1 (4EBP1)] were analyzed throughout normal pregnancy in rats. In addition, we used an ovariectomized (OVX) rat model to analyze the modulation of the mTOR pathway and proliferative activity of the uterine myocytes by estradiol alone and in combination with the mTOR-specific inhibitor rapamycin. Our results demonstrate that insulin receptor substrate-1 protein levels and the phosphorylated (activated) forms of PI3K, mTOR, and S6K1 were significantly up-regulated in the rat myometrium during the proliferative phase of pregnancy. Treatment of the OVX rats with estradiol caused a transient increase in IGF-I followed by an up-regulation of the PI3K/mTOR pathway, which became apparent by a cascade of phosphorylation reactions (P-P85, P-Akt, P-mTOR, P-S6K1, and P-4EBP1). Rapamycin blocked activation of P-mTOR, P-S6K1, and P-4EBP1 proteins and significantly reduced the number of proliferating cells in the myometrium of OVX rats. Our in vivo data demonstrate that estradiol was able to activate the PI3K/mTOR signaling pathway in uterine myocytes and suggest that this activation is responsible for the induction of myometrial hyperplasia during early gestation.
Dissociation between Rat Hippocampal CA1 and Dentate Gyrus Cells in Their Response to Corticosterone: Effects on Calcium Channel Protein and Current
Authors: van Gemert Neeltje G. , Carvalho Diana M. M. , Karst Henk , van der Laan Siem , Zhang Mingxu , Meijer Onno C. , Hell Johannes W. , Joëls Marian
Published: July 2009

Stress and corticosterone affect, via glucocorticoid receptors, cellular physiology in the rodent brain. A well-documented example concerns corticosteroid effects on high-voltage activated (L type) calcium currents in the hippocampal CA1 area. We tested whether corticosterone also affects calcium currents in another hippocampal area that highly expresses glucocorticoid receptors, i.e. the dentate gyrus (DG). Remarkably, corticosterone (100 nm, given for 20 min, 1–4.5 hr before recording) did not change high-voltage activated calcium currents in the DG, whereas currents in the CA1 area of the same rats were increased. Follow-up studies revealed that no apparent dissociation between the two areas was observed with respect to transcriptional regulation of calcium channel subunits; thus, in both areas corticosterone increased mRNA levels of the calcium channel-β4 but not the (α) Cav1.2 subunit. At the protein level, however, β4 and Cav1.2 levels were significantly up-regulated by corticosterone in the CA1 but not the DG area. These data suggest that stress-induced elevations in the level of corticosterone result in a regionally differentiated physiological response that is not simply determined by the glucocorticoid receptor distribution and that the observed regional differentiation may be caused by a gene involved in the translational machinery or in mechanisms regulating mRNA or protein stability.
Nkx6-1 controls the identity and fate of red nucleus and oculomotor neurons in the mouse midbrain
Authors: Prakash Nilima , Puelles Eduardo , Freude Kristine , Trümbach Dietrich , Omodei Daniela , Di Salvio Michela , Sussel Lori , Ericson Johan , Sander Maike , Simeone Antonio , Wurst Wolfgang
Published: July 2009

Little is known about the cues controlling the generation of motoneuron populations in the mammalian ventral midbrain. We show that Otx2 provides the crucial anterior-posterior positional information for the generation of red nucleus neurons in the murine midbrain. Moreover, the homeodomain transcription factor Nkx6-1 controls the proper development of the red nucleus and of the oculomotor and trochlear nucleus neurons. Nkx6-1 is expressed in ventral midbrain progenitors and acts as a fate determinant of the Brn3a+ (also known as Pou4f1) red nucleus neurons. These progenitors are partially dorsalized in the absence of Nkx6-1, and a fraction of their postmitotic offspring adopts an alternative cell fate, as revealed by the activation of Dbx1 and Otx2 in these cells. Nkx6-1 is also expressed in postmitotic Isl1+ oculomotor and trochlear neurons. Similar to hindbrain visceral (branchio-) motoneurons,Nkx6-1 controls the proper migration and axon outgrowth of these neurons by regulating the expression of at least three axon guidance/neuronal migration molecules. Based on these findings, we provide additional evidence that the developmental mechanism of the oculomotor and trochlear neurons exhibits more similarity with that of special visceral motoneurons than with that controlling the generation of somatic motoneurons located in the murine caudal hindbrain and spinal cord.
Lighting up mRNA localization inDrosophilaoogenesis
Authors: Becalska Agata N. , Gavis Elizabeth R.
Published: July 2009

The asymmetric localization of four maternal mRNAs - gurken, bicoid,oskar and nanos - in the Drosophila oocyte is essential for the development of the embryonic body axes. Fluorescent imaging methods are now being used to visualize these mRNAs in living tissue, allowing dynamic analysis of their behaviors throughout the process of localization. This review summarizes recent findings from such studies that provide new insight into the elaborate cellular mechanisms that are used to transport mRNAs to different regions of the oocyte and to maintain their localized distributions during oogenesis.
Regulation of cell surface protease matriptase by HAI2 is essential for placental development, neural tube closure and embryonic survival in mice
Authors: Szabo Roman , Hobson John P. , Christoph Kristina , Kosa Peter , List Karin , Bugge Thomas H.
Published: July 2009

Hypomorphic mutations in the human SPINT2 gene cause a broad spectrum of abnormalities in organogenesis, including organ and digit duplications, atresia, fistulas, hypertelorism, cleft palate and hamartoma. SPINT2 encodes the transmembrane serine protease inhibitor HAI2(placental bikunin), and the severe developmental effects of decreased HAI2 activity can be hypothesized to be a consequence of excess pericellular proteolytic activity. Indeed, we show here that HAI2 is a potent regulator of protease-guided cellular responses, including motogenic activity and transepithelial resistance of epithelial monolayers. Furthermore, we show that inhibition of the transmembrane serine protease matriptase (encoded by St14) is an essential function of HAI2 during tissue morphogenesis. Genetic inactivation of the mouse Spint2 gene led to defects in neural tube closure, abnormal placental labyrinth development associated with loss of epithelial cell polarity, and embryonic demise. Developmental defects observed in HAI2-deficient mice were caused by unregulated matriptase activity, as both placental development and embryonic survival in HAI2-deficient embryos were completely restored by the simultaneous genetic inactivation of matriptase. However, neural tube defects were detected in HAI2-deficient mice even in the absence of matriptase, although at lower frequency, indicating that the inhibition of additional serine protease(s) by HAI2 is required to complete neural development. Finally, by genetic complementation analysis, we uncovered a unique and complex functional interaction between HAI2 and the related HAI1 in the regulation of matriptase activity during development. This study indicates that unregulated matriptase-dependent cell surface proteolysis can cause a diverse array of abnormalities in mammalian development.
Forward and reverse mappings of the tungsten inert gas welding process using radial basis function neural networks
Authors: Amarnath M V , Pratihar D K
Published: July 2009

In the present study, forward and reverse mapping problems of the tungsten inert gas (TIG) welding process have been solved using radial basis function neural networks (RBFNNs), which is required to automate the welding process. The performance of an RBFNN depends on its structure and parameters. Here, a few approaches are proposed to optimize its structure and parameters simultaneously. A binary-coded genetic algorithm (GA) has been used for the said purpose. The GA strings carrying information of the networks might have varied lengths, and consequently, it becomes difficult to implement the conventional crossover operator. To overcome this difficulty, a new scheme has been adopted here. The performances of the developed approaches are tested to conduct both forward and reverse mappings of a TIG welding process. Cluster-based approaches are found to perform better than the non-cluster-based ones.
Experimental study on electrodischarge machining in water of D2 tool steel using two different electrode materials
Authors: Medellin H I , de Lange D F , Morales J , Flores A
Published: July 2009

Water as the dielectric in electrodischarge machining (EDM) is an alternative to traditional hydrocarbon oil to promote a better working environment from the perspective of health and safety, as it does not decompose and release harmful vapours (CO and CH4). In order to enhance the understanding of water as a dielectric, this paper presents an investigation of the EDM performance on D2 tool steel using water as the dielectric. The experiment was carried out using different types of water (tap water, deionized water, and mixtures of tap and deionized water) and two different electrode materials: brass and bronze. The results have shown that the greatest EDM performance, which corresponds to the maximum material removal rate (MRR) and the minimum tool wear rate (TWR), is achieved with a mixture of 75 per cent tap water and 25 per cent deionized water as the dielectric, while deionized water resulted in the worst performance. Finally, a case study of a forming die with a complex shape was machined using the results obtained in this investigation.
An autoignition combustion model for homogeneous charge compression ignition engine cycle simulations
Authors: Potrzebowski A , Misztal J , Xu H-M , Wyszynski M L , Qiao J
Published: July 2009

This paper presents an autoignition combustion model, which can be used in conjunction with a one-dimensional gas dynamics and zero-dimensional thermodynamics engine simulation code for homogeneous charge compression ignition (HCCI) engine cycle simulations. The model consists of two parts: the first predicts autoignition timing, based on the integral of the knock delay time, and the second predicts the heat release rate, based on the Watson correlation for diesel engines. The equations for the model were fitted with empirical coefficients derived from experimental results. The experimental data were measured under a number of engine operating conditions for different loads, speeds, and equivalence ratios. The experiments were performed on a Jaguar V6 HCCI engine employing internal exhaust gas residual trapping through cam profile switching and variable valve timing control. It was found that the location of 50 per cent mass fraction burned (MFB) and the peak rate of pressure rise can be chosen as the key parameters charactering the HCCI combustion in engine simulations. The fitted combustion model was then implemented into the V6 engine Ricardo WAVETM model and validation of its predictive calculations was obtained using a different set of experimental data. The results show that the predicted 50 per cent MFB position is within an average error of 1.84° crank angle (CA) and the predicted peak rate of pressure rise is within an average error of 0.53bar/deg CA (7.2 per cent).
A study on the estimation of SWIFT model parameters by finite element analysis
Authors: Balaramakrishna N , Kumar R Krishna
Published: July 2009

The SWIFT model is an extension of the MF-Tyre model developed by TNO and Delft University of Technology. This model, applicable up to 60Hz longitudinal frequency, considers envelopment characteristics of the tyre. This paper presents the finite element analysis (FEA) approach to arrive at the 172 SWIFT model parameters. A 235/75R15 tyre is modelled using the commercial software package ABAQUS. The mixed Lagrangian—Eulerian approach has been used to simulate the loaded radius and contact length. Envelopment and cleat simulations are done with an explicit solver. The data curve fitted with MF Tool are found to be reasonable. This technique can be used to obtain SWIFT model parameters so that the vehicle dynamic behaviour of the tyre—vehicle combination can be virtually assessed before a real tyre is built; this will significantly reduce the tyre development time.
Metamodel-based lightweight design of an automotive front-body structure using robust optimization
Authors: Zhu P , Zhang Y , Chen G-L
Published: July 2009

Both conventional automobiles and new energy cars require urgently lightweight design to realize energy economy and environmental protection in a long run. The weight reduction of the body structure plays a rather important role in decreasing the weight of the full vehicle. In real engineering problems, the variation in sheet gauge, geometrical size, and material parameters caused by environmental factors and other uncertainties may affect the structural performances of body components. Therefore, a lightweight design without considering this kind of tolerance may result in the loss of feasibility and reliability in engineering application. From the viewpoint of crashworthiness performance, this paper presents a study on the lightweight design of the automotive front-body structure based on robust optimization, considering the variation in design variables including sheet gauge and yield limit of materials. Coupled with the design and analysis of a computer experiment, four metamodelling techniques, namely support vector regression, kriging, radial basis functions, and artificial neural networks, are employed to build the metamodels of structural crashworthiness performance indicators for comparison of approximation accuracy. An adaptive deterministic optimization process is used to upgrade further the approximation accuracy of metamodels for the following robust optimization. A double-loop strategy is chosen when solving the robust optimization formulation and the basic Monte Carlo simulation method is applied to perform a reliability analysis. A genetic algorithm solver is used to obtain both the deterministic and the robust optimum results for comparison. The reduced weight obtained by using robust optimization is 7.8003kgf (19.45 per cent) and the result achieved from robust optimization is more conservative than that obtained through deterministic optimization as expected. However, the robust optimum design is ensured to be feasible and reliable when the variation in design variables works in a real engineering application.
Development of an electronic control unit for a compressed natural gas engine, based on circuit simulation and modelling
Authors: Wang J-X , Song J-H , Mao X-J , Wang D , Tang H-B , Zhuo B
Published: July 2009

An electronic control unit (ECU) is designed for a compressed natural gas (CNG) engine on the basis of circuit simulation and modelling. The ignition drive circuit and power-off delay circuit are discussed, with emphasis on circuit simulation, and resistance matching for the sensor processing circuit is described. Design of the software of the CNG control system is based on modelling. A TargetLink model of an air—fuel ratio closed-loop control system is presented. The CNG ECU has been applied successfully in bench tests. The results of bench tests have shown that the hardware meets CNG control system requirements; actuators can be controlled precisely, and the performance of the CNG engine can reach design targets. Circuit simulation and modelling are good methods for developing the ECU design for CNG engine systems. Quality of hardware and software design can be ensured, and the development cycle and costs can be reduced.
Look-ahead control — consequences of a non-linear fuel map on truck fuel consumption
Authors: Ivarsson M , Åslund J , Nielsen L
Published: July 2009

Consequences of non-linearities in specific fuel consumption (SFC) of a heavy truck combustion engine are studied with focus on such small road gradients that a constant speed is optimal if the engine torque has an affine relation to fuelling. A quasi-static analysis gives valuable insights into the intrinsic properties of minimization of fuel consumption. Two objective functions are shown to give different optimal velocity trajectories on a constant road gradient, when the non-linearity in SFC is significant, a notation which is quantified. For a significant non-linearity, when a constraint is set to keep a final time, switching between two characteristic speeds is optimal. Alternatively, if consumed time, in addition to fuel consumption, is part of the objective function, then keeping to one constant speed is optimal also for significant non-linearities. However, the different optimal solutions still show similarities, since for a certain significant non-linearity a specific speed range determined by the characteristic velocities is shown to be unobtainable for both optimality criteria. Similar results are obtained for a full dynamic model including a realistic fuel map and other realistic constraints.
Modelling, simulation, and experimental verification of the kinematics and dynamics of a double wishbone suspension configuration
Authors: Cherian V , Jalili N , Ayglon V
Published: July 2009

This paper describes the non-linear modelling of a double wishbone suspension developed to investigate the non-linear kinematics and dynamics in the closed, spatial kinematic chain configuration. Analytical and ADAMS models are generated and kinematic and dynamic characteristics of the models are investigated. The analytical model of the suspension mechanism is an idealized four degree-of-freedom (DOF) model, with suspension members considered as rigid links and bushings taken as linear spring—damper elements. The simulation results of the model subjected to a virtual kinematics and compliance (K&C) test are compared with results generated by an ADAMS model, developed based on parameters obtained from the vehicle manufacturer, subjected to the same virtual test. The experimental K&C testing on the test vehicle presents a method of capturing the kinematic characteristics of the suspension mechanism. The comparison of the simulation and experimental results presented shows that the models are capable of simulating the characteristics of the pre-existing suspension configuration of the test vehicle.
Experimental investigation of the effect of the intake air temperature and mixture quality on the combustion of a methanol- and gasoline-fuelled homogeneous charge compression ignition engine
Authors: Maurya R K , Agarwal A K
Published: July 2009

Environmental concerns have increased significantly all over the world in the past decade. To fulfil the simultaneous emission requirements for near-zero pollutant and low carbon dioxide (CO2) levels, which are the challenges for the future powertrains, many studies are currently being carried out on new engine combustion processes, such as controlled autoignition for gasoline engines and homogeneous charge compression ignition (HCCI) for diesel engines. These combustion processes have the potential for ultra-low nitrogen oxide (NO x) and particulate matter emissions in comparison with conventional gasoline or diesel engines.

In this paper, the combustion characteristics of a HCCI engine fuelled with methanol and gasoline were investigated on a modified two-cylinder four-stroke engine. The port fuel injection technique is used to prepare a homogeneous charge of fuel and air. The experiment is conducted with various intake air temperatures ranging from 120°C to 160°C at different air-to-fuel ratios, for which stable HCCI combustion is achieved. The experimental results indicate that the inlet air temperature and air-to-fuel ratio have a significant effect on the maximum in-cylinder pressure and its position relative to top dead centre, the shape of the pressure rise curve, and the heat release rates. The results confirm that the inlet air temperature is a very sensitive parameter in controlling combustion timing and thus the effectiveness of the HCCI combustion process.
Heuristic and exact techniques for aircraft maintenance scheduling
Authors: Chiesa S , Quer S , Corpino S , Viola N
Published: July 2009

Aircraft's availability is certainly one of the most important features of modern avionic industry. High availability can only be obtained with very efficient maintenance cycles. These cycles, in turn, are extremely expensive in terms of tools and personnel. This article describes the main features of an aircraft maintenance cycle contrasting it with other similar scheduling tasks. After that, it demonstrates how to model a maintenance cycle to enable a symbolic (mathematical) analysis, and it shows how to create a plan with both heuristic and symbolic (exact) techniques. Heuristic techniques show high efficiency and scalability, but they deliver sub-optimal results, and are then unable to minimize maintenance costs. Exact techniques are able to find optimal solutions even for very constrained tasks. Unfortunately, even the most efficient exact strategy is not able to deal with real (complete) maintenance problems. As a consequence, heuristic and exact strategies are used together to trade-off the accuracy of the result with the capacity of the considered problems. From the experimental point of view, the article reports data on real maintenance tasks coming from the avionic industry. It describes how to discover and to correct error coded in the original database, which all previous manual analyses were unable to reveal. The final scheduling shows consistent improvements against the original manual planning adopted on the field so far.
Motion analysis of deployable structures based on the rod hinge element by the finite particle method
Authors: Yu Y , Luo Y Z
Published: July 2009

Deployable structures have been widely used in civil engineering and space technology for their versatility in meeting the practical requirements. Using the finite particle method (FPM), this article presents a motion analysis of deployable structures based on the straight-rod hinge and angulated-rod hinge. The FPM is a recently proposed method that is based on the combination of the vector mechanics and numerical calculations. It models the analysed domain composed of finite particles. Newton's second law is adopted to describe the motions of all particles. FPM can simultaneously calculate large rigid body motions and large geometrical changes of a structural system. There is no need to solve any non-linear equations, to calculate the stiffness matrix or equilibrium matrix, which is very helpful in the motion analysis of deployable structures. The fundamentals of this method are given first, including the basic motion equation, the derivation for planar element, and solution procedures of this method. The rod hinge element is developed to model the deployable structure. Two deployable structures based on different elements are analysed with the same program. From the simulation results, the article shows the capabilities and accuracy of this method in the motion analysis of deployable structures.
Estimating clamping pressure distribution and stiffness in aircraft bolted joints by finite-element analysis
Authors: Oskouei R H , Keikhosravy M , Soutis C
Published: July 2009

In this study, a finite-element (FE) stress analysis of aircraft structural double-lap bolted joints was performed using the commercially available computational package ANSYS in order to obtain the clamping pressure distribution and to estimate the stiffness of the joined plates (members) within the clamped region. The joint consists of three aluminium alloy 7075-T6 plates clamped by a single bolt, washer, and nut. A three-dimensional (3D) FE model of the joint was generated, and then subjected to three different simulated clamping forces. 3D surface-to-surface contact elements were employed to model the contact between the various components of the bolted joint. The model included friction between all contacting surfaces, and also a clearance between the bolt shank and the joint hole. FE results revealed an overall crock-shaped pressure distribution at the joined plates. Moreover, some beneficial longitudinal compressive stresses were observed around the fastener hole as a result of the clamping compressive effect.
Zirconia–parylene multilayer thin films for enhanced fracture resistance of dental ceramics
Authors: Teixeira E C , Piascik J R , Stoner B R , Thompson J Y
Published: July 2009

Recent research has shown that the application of specific thin films can enhance the material properties of a laminate construct. In this study, the effect of different mono/multilayered films on the strength of a ceramic specimen is demonstrated. It is well established that cracks can initiate and/or propagate from the internal surfaces of all-ceramic dental restorations. Modifying that surface by thin-film deposition might help increase clinical longevity and applicability. Specimens were divided into the following groups according to different surface treatments received: uncoated (control group), 10 μm yttria-stabilized zirconia (YSZ) thin film, 10 μm parylene thin film, 9.75 μm YSZ + 0.25 μm parylene film, and a multilayered film (five layers of 1.25 μm YSZ + 0.75 μm parylene). Depositions were performed using a radio-frequency magnetron sputter system (working pressure 15 mT, 150 °C, 30:1 Ar/O2 gas ratio) to produce the YSZ layers, and a vapour deposition process was used to produce the parylene layers. Flexural strength measurements were carried out by three-point bending (span = 10 mm) in a servo-electric material testing system in deioinized (DI) water (37 °C). The results showed that the strength of the specimen significantly increased with the deposition of all types of coating, showing the greatest increase with the multilayered film (∼32 per cent). It is hypothesized that a multilayer thin film (brittle/ductile) can promote crack deflection, causing strength enhancement of the brittle construct.
Feedback control of the neuromusculoskeletal system in a forward dynamics simulation of stair locomotion
Authors: Selk Ghafari A , Meghdari A , Vossoughi G
Published: July 2009

The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of pressure during locomotion. The parameters of the proposed controller were determined by employing the iterative feedback tuning approach to minimize tracking errors during forward dynamics simulation. Simultaneously, an inverse-dynamics-based optimization was employed to compute a set of desired musculotendon forces in the closed-loop simulation to resolve muscle redundancy. Quantitative comparisons of the simulation results with the experimental measurements and the reference muscles' activities illustrate the accuracy and efficiency of the proposed method during the stable ascending simulation.
A numerical tool for the reconstruction of the physiological kinematics of the glenohumeral joint
Authors: Amadi H O , Hansen U N , Bull A M J
Published: July 2009

The aim of this study was to develop and test a robust approach to apply a joint coordinate system (JCS) to imaging data sets of the glenohumeral joint and to reconstruct the kinematics with six degrees of freedom (6DOF) in order to investigate shoulder pathologies related to instability. Visible human data were used to reconstruct bony morphology. Landmarks were used to define axes for body-fixed Cartesian coordinate frames on the humerus and scapula. These were applied to a three-cylinder open-chain JCS upon which the humeral 6DOF motions relative to the scapula were implemented. Software was written that applies 6DOF input variables to rotate and translate the nodes of the surface geometry of the humerus relative to the scapula in a global coordinate frame. The instantaneous relative position and orientation of the humerus for a given set of variables were thus reconstructed on the bone models for graphical display. This tool can be used for graphical animation of shoulder kinematics, demonstrating clinical assessments, and allowing further analysis of the function of tissues within the joint.
Development of a customized density—modulus relationship for use in subject-specific finite element models of the ulna
Authors: Austman R L , Milner J S , Holdsworth D W , Dunning C E
Published: July 2009

Assigning an appropriate density—modulus relationship is an important factor when applying inhomogeneous material properties to finite element models of bone. The purpose of this study was to develop a customized density—modulus equation for the distal ulna, using beam theory combined with experimental results. Five custom equations of the form E = aρb were used to apply material properties to models of eight ulnae. All equations passed through a point (1.85, Ec), where ρ = 1.85 g/cm3 represents the average density of cortical bone. For custom equations (1) to (3), Ec was predicted using beam theory, and the value of b was varied within the range reported in the literature. Custom equations (4) and (5) used other values of Ec from the literature, while keeping b constant. Results obtained from the custom equations were compared with those from other equations in the literature, and with experimental results. The beam theory analysis predicted Ec = 21 ± 1.6 GPa, and the three custom equations using this value tended to have the lowest errors. The power of the equations did not affect the results as much as the value used for Ec. Overall, a customized density—modulus relationship for the ulna was generated, which provided improved results over using previously reported density—modulus equations.
Design and implementation of robust controllers for a gait trainer
Authors: Wang F-C , Yu C-H , Chou T-Y
Published: July 2009

This paper applies robust algorithms to control an active gait trainer for children with walking disabilities. Compared with traditional rehabilitation procedures, in which two or three trainers are required to assist the patient, a motor-driven mechanism was constructed to improve the efficiency of the procedures. First, a six-bar mechanism was designed and constructed to mimic the trajectory of children's ankles in walking. Second, system identification techniques were applied to obtain system transfer functions at different operating points by experiments. Third, robust control algorithms were used to design H∞ robust controllers for the system. Finally, the designed controllers were implemented to verify experimentally the system performance. From the results, the proposed robust control strategies are shown to be effective.
An in-vivo model of functional head impact testing in non-helmeted athletes
Authors: Higgins M J , Tierney R T , Caswell S , Driban J B , Mansell J , Clegg S
Published: July 2009

Development of a functional in-vivo head impact testing model would enhance the ability to elucidate mechanisms underlying individual responses to head impact in sports where a helmet is not worn. The objective of this paper is to describe a novel in-vivo method of assessing human head linear impact acceleration during the functional activity of soccer heading, using a repeated-measures design in a university research laboratory. 17 college-aged soccer players (age, 20.93 years (standard deviation (SD), 1.17 years); height, 170.39cm (SD, 10.15cm); mass, 71.50kg (SD, 9.89kg); head—neck mass, 5.90kg (SD, 0.83kg)) participated in this study. All participants read and signed a university Institutional-Review-Board-approved informed consent before participating.

The resultant linear head acceleration (in units of g) was measured for each participant during soccer heading. The head impact model consisted of controlled soccer headers and a triaxial accelerometer affixed to a custom-fitted mouthpiece. A force-sensitive resistor on the forehead assessed impact quality. Standard soccer balls were projected from a JUGS soccer machine travelling at 11.10m/s (25mile/h) and covering a distance of 11m (35ft). The subjects performed standing or simulated headers while aiming at a target positioned 5m in front of them. The intra-class correlation coefficient (ICC2,1) was 0.845 for resultant accelerations.

In this paper, the development and testing of a novel in-vivo functional human head impact testing model are described. Results suggest that this methodology has potential for assessing resultant peak linear head impact accelerations during the functional activity of soccer heading and in other non-helmet-wearing sports.