Car Domain Research Articles

A Petri-Net Based Context Representation in Smart Car Environment

Driving is a complex process influenced by a wide range of factors, especially complex interactions between the driver, the vehicle, and the environment. This paper represents the complex situations in smart car domain. Unlike existing context-aware systems which isolate one context situation from another, such as road congestion and car deceleration, this paper proposes a context model which considers the driver, vehicle and environment as a whole. The paper tries to discover the inherent relationship between the situations in the smart car environment, and proposes a context model to support the representation of situations and their correlation. The detailed example scenarios are given to illustrate our idea.

Intra-vehicular verification and control: a two-pronged approach

Modern vehicles are equipped with hundreds of embedded networked components with computational, sensory and actuation powers. Reliable functioning and interaction of these components are vital for the safety of the vehicle and its passengers. The authors present an architecture that deals with the intra-vehicular network at both component and system levels. At the component level, the technique formally verifies compatibility of each component with the rest of the system. At the system level, the authors provide means to define overall behavior by using first-order logic rules in an ontological space. Overall, they eliminate the hazards associated with integrating heterogeneous components in a car network domain and enable a knowledgeable user to define network behavior easily.

Contextual alignment of ontologies in the eCOIN semantic interoperability framework

The prospect of combining information from diverse sources for superior decision making is plagued by the challenge of semantic heterogeneity, as data sources often adopt different conventions and interpretations when there is no coordination. An emerging solution in information integration is to develop an ontology as a standard data model for a domain of interest, and then to define the correspondences between the data sources and this common model to eliminate their semantic heterogeneity and produce a single integrated view of the data sources. We first claim that this single integrated view approach is unnecessarily restrictive, and instead offer the view that ontologies can simultaneously accommodate multiple integrated views provided the accompaniment of contexts, a set of axioms on the interpretation of data allowing local variations in representation and nuances in meaning, and a conversion function network between contexts to reconcile contextual differences. Then, we illustrate how to achieve semantic interoperability between multiple ontology-based applications. During this process, application ontologies are aligned through the reconciliation of their context models, and a new application with a virtual merged ontology is created. We illustrate this alternative approach with the alignment of air travel and car rental domains, an actual example from our prototype implementation.

Contextual Alignment of Ontologies in the eCoin Semantic Interoperability Framework

The prospect of combining information from diverse sources for superior decision making is plagued by the challenge of semantic heterogeneity, as data sources often adopt different conventions and interpretations when there is no coordination. An emerging solution in information integration is to develop an ontology as a standard data model for a domain of interest, and then to define the correspondences between the data sources and this common model to eliminate their semantic heterogeneity and produce a single integrated view of the data sources. We first claim that this single integrated view approach is unnecessarily restrictive, and instead offer the view that ontologies can simultaneously accommodate multiple integrated views provided the accompaniment of contexts, a set of axioms on the interpretation of data allowing local variations in representation and nuances in meaning, and a conversion function network between contexts to reconcile contextual differences. Then, we illustrate how to achieve semantic interoperability between multiple ontology-based applications. During this process, application ontologies are aligned through the reconciliation of their context models, and a new application with a virtual merged ontology is created. We illustrate this alternative approach with the alignment of air travel and car rental domains, an actual example from our prototype implementation.

Functional analysis of four naturally occurring variants of human constitutive androstane receptor

The human constitutive androstane receptor (CAR, NR1I3) is a member of the orphan nuclear receptor superfamily that plays an important role in the control of drug metabolism and disposition. In this study, we sequenced all the coding exons of the NR1I3 gene for 334 Japanese subjects. We identified three novel single nucleotide polymorphisms (SNPs) that induce non-synonymous alterations of amino acids (His246Arg, Leu308Pro, and Asn323Ser) residing in the ligand-binding domain of CAR, in addition to the Val133Gly variant, which was another CAR variant identified in our previous study. We performed functional analysis of these four naturally occurring CAR variants in COS-7 cells using a CYP3A4 promoter/enhancer reporter gene that includes the CAR responsive elements. The His246Arg variant caused marked reductions in both transactivation of the reporter gene and in the response to 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime (CITCO), which is a human CAR-specific agonist. The transactivation ability of the Leu308Pro variant was also significantly decreased, but its responsiveness to CITCO was not abrogated. The transactivation ability and CITCO response of the Val133Gly and Asn323Ser variants did not change as compared to the wild-type CAR. These data suggest that the His246Arg and Leu308Pro variants, especially His246Arg, may influence the expression of drug-metabolizing enzymes and transporters that are transactivated by CAR.

Trends in Automotive Communication Systems

The use of networks for communications between the electronic control units (ECU) of a vehicle in production cars dates from the beginning of the 1990s. The specific requirements of the different car domains have led to the development of a large number of automotive networks such as Local Interconnect Network, J1850, CAN, TTP/C, FlexRay, media-oriented system transport, IDB1394, etc. This paper first introduces the context of in-vehicle embedded systems and, in particular, the requirements imposed on the communication systems. Then, a comprehensive review of the most widely used automotive networks, as well as the emerging ones, is given. Next, the current efforts of the automotive industry on middleware technologies, which may be of great help in mastering the heterogeneity, are reviewed. Finally, we highlight future trends in the development of automotive communication systems.

Molecular cloning of the gene encoding pregnane X receptor (PXR; NR1I2) and the constitutive androstane receptor (CAR; NR1I3) in pigs

The pregnane X receptor (PXR; NR1I2) and the constitutive androstane receptor (CAR; NR1I3) are members of the nuclear receptor superfamily that act as transcription factors. They regulate the expression of several important genes that encode enzymes responsible for the metabolism of endogenous hormones and exogenous substances. We determined the nucleotide sequences of porcine CARand PXR genes bp using cDNA clones derived from porcine cDNA libraries. The porcine CAR gene has a 1407 bp mRNA, which contains a 216 bp 5'-untranslated region (UTR), a 144 bp 3'-UTR, and a 1047 bp coding region that encodes 348 amino acids. The mRNA sequence of porcine PXR is composed of 2567 bp that contains a 273 bp 5'-UTR, a 1266 bp putative coding region encoding 421 amino acids, and a 1028 bp 3'-UTR. The porcine CAR and porcine PXR proteins showed a high degree of sequence identity in their DNA-binding domain (DBD) and ligand-binding domain (LBD) with 80% - 90% amino acid identity in comparison with those of humans. However, the AB domain of the porcine CAR and PXR proteins is considerably different in comparison with that of humans. Eighty six percentage and 43 % sequence identity is found between porcine and human CAR proteins and porcine and human PXR proteins, respectively. The mRNA expression of both porcine CAR and PXR was detected in liver, small intestine, and kidney bp using reverse-transcription (RT) -PCR.

Contextual Alignment of Ontologies for Semantic Interoperability

Virtually all of the existing approaches to ontology integration assume that each of the individual ontologies (and the integrated ontology) corresponds to a single set of semantics at a given time. We first claim that this single integrated view assumption is unnecessarily restrictive, and defend the view that ontologies can simultaneously accommodate multiple integrated views provided the accompaniment of contexts - a set of axioms on the interpretation of data allowing local variations in representation and nuances in meaning, and a conversion function network between contexts to reconcile contextual differences. Then, we propose an ontology integration methodology based on the alignment of contexts and linking conversion function networks defined between contexts. The flexibility of our approach and methodology is illustrated with the alignment of air travel and car rental domains, an actual example from our prototype implementation.

Insights from a three-dimensional model into ligand binding to constitutive active receptor.

Two orphan nuclear receptors, constitutive active (or androstane) receptor (CAR) and pregnane X receptor (PXR), are among the most important mediators of ligand-activated transcriptional induction of liver microsomal cytochrome P450 drug-metabolizing enzymes. CAR and PXR belong to the same NR1I receptor subfamily and show high sequence homology to each other. The vitamin D receptor (VDR) also belongs to the NR1I subfamily and has the second highest homology to CAR in the ligand binding domain. A 3D model of the ligand binding domain of human CAR (hCAR) was constructed based on the available X-ray structures of human PXR (hPXR) and VDR (hVDR). The model shows that the size of the ligand binding cavities of hCAR and hPXR are similar, but larger than that of hVDR. hPXR's capability of binding to extremely large ligands, such as rifampicin, implies that its binding cavity may be able to expand further through the flexibility of a surface loop. In contrast, hCAR does not have this loop so that its cavity cannot expand, suggesting that hCAR would not bind to the largest hPXR ligands. Docking calculations of selected ligands to hCAR, based on the structural model, are consistent with previously reported receptor binding data. The results from this study indicate that structural modeling will be a useful tool for understanding ligand binding to hCAR and for design of drugs free of hCAR-mediated enzyme induction.

Apical localization of the coxsackie-adenovirus receptor by glycosyl-phosphatidylinositol modification is sufficient for adenovirus-mediated gene transfer through the apical surface of human airway epithelia.

In well-differentiated human airway epithelia, the coxsackie B and adenovirus type 2 and 5 receptor (CAR) resides primarily on the basolateral membrane. This location may explain the observation that gene transfer is inefficient when adenovirus vectors are applied to the apical surface. To further test this hypothesis and to investigate requirements and barriers to apical gene transfer to differentiated human airway epithelia, we expressed CAR in which the transmembrane and cytoplasmic tail were replaced by a glycosyl-phosphatidylinositol (GPI) anchor (GPI-CAR). As controls, we expressed wild-type CAR and CAR lacking the cytoplasmic domain (Tailless-CAR). All three constructs enhanced gene transfer with similar efficiencies in fibroblasts. In airway epithelia, GPI-CAR localized specifically to the apical membrane, where it bound adenovirus and enhanced gene transfer to levels obtained when vector was applied to the basolateral membrane. Moreover, GPI-CAR facilitated gene transfer of the cystic fibrosis transmembrane conductance regulator to cystic fibrosis airway epithelia, correcting the Cl(-) transport defect. In contrast, when we expressed wild-type CAR it localized to the basolateral membrane and failed to increase apical gene transfer. Only a small amount of Tailless-CAR resided in the apical membrane, and the effects on apical virus binding and gene transfer were minimal. These data indicate that binding of adenovirus to an apical membrane receptor is sufficient to mediate effective gene transfer to human airway epithelia and that the cytoplasmic domain of CAR is not required for this process. The results suggest that targeting apical receptors in differentiated airway epithelia may be sufficient for gene transfer in the genetic disease cystic fibrosis.

Mutational analysis of the cysteines in the extracellular domain of the human Ca 2+ receptor: effects on cell surface expression, dimerization and signal transduction

Mammalian calcium receptors (CaRs) share with the metabotropic glutamate receptors (mGluRs) the relative positions of 16 cysteine residues in the amino-terminal extracellular domain. To investigate the role of these cysteines, a series of mutants in the extracellular domain of the human CaR was prepared in which each of these 16 cysteine residues and three others not conserved in the mGluRs were replaced by serines. Wild-type and mutant CaR cDNAs were expressed in HEK-293 cells, and evaluated for expression and response to extracellular calcium. Mutation of three non-conserved cysteines and of two conserved cysteines produced proteins with near wild-type phenotype. In contrast, mutation of the other conserved cysteines gave proteins that showed drastic reduction in cell surface expression and/or failed to respond to calcium. We identified 14 cysteines essential for proper trafficking and function of the receptor, two of which may be involved in formation of a disulfide-linked dimer.

Construction of problem-solving methods as parametric design

The knowledge-engineering literature contains a number of approaches for constructing or selecting problem solvers. Some of these approaches are based on indexing and selecting a problem solver from a library, others are based on a knowledge acquisition process, or are based on search-strategies. None of these approaches sees constructing a problem solver as a configuration task that could be solved with an appropriate configuration method. We introduce a representation of the functionality of problem-solving methods that allows us to view the construction of problem solvers as a configuration problem, and specifically as a parametric design problem. From the available methods for parametric design, we use propose-critique-modify for the automated configuration of problem-solving methods. We illustrate this approach by a scenario in a small car domain example.

Cloning, expression, and tissue localization of the calcium-sensing receptor in chicken (Gallus domesticus).

In previous studies, we characterized an extracellular Ca2+ (Cao(2+))-sensing receptor (CaR) that plays a central role in regulating parathyroid hormone secretion in mammals by sensing Cao2+. In the present study, we have cloned and characterized the chicken (Gallus domesticus) homolog of the CaR. The chicken parathyroid CaR shares a high degree of homology (84% amino acid identity) with the human CaR and displays a similar topology. Moreover, amino acid residues where mutations cause disorders of Cao(2+)-sensing in the human CaR share the wild-type human sequence in the chicken CaR. However, a single region in the extracellular domain of the chicken CaR differs substantially from its mammalian homologs. Xenopus laevis oocytes injected with chicken CaR cRNA respond to elevated ambient levels of Cao2+, extracellular Mg2+, or extracellular Gd3+ with the characteristic activation of inositol trisphosphate-dependent, intracellular Ca(2+)-induced Cl- currents elicited by mammalian CaRs as well as by G protein-linked receptors coupled to activation of phospholipase C. By in situ hybridization, clusters of cells in chicken parathyroid glands were shown to express CaR messenger RNA. Northern analysis and immunohistochemistry demonstrated expression of receptor transcripts and/or protein in kidney tubules and intestine as well as in brain. The close conservation of the amino acid sequence of the chicken CaR with its mammalian homologs as well as its similar tissue distribution suggest that the receptor may also play an important role in avian calcium homeostasis.

Calcium-Dependent c-mycProto-Oncogene Expression and Proliferation of CACO-2 Cells: A Role for a Luminal Extracellular Calcium-Sensing Receptor

The human colonic cell line Caco-2 responds to a reduction of ambient [Ca++]o to levels at and below 0.25 mM by a twofold increase in [3H]thymidine labelling of their DNA. [Ca++]o signals sensed preferentially across the luminal aspect of Caco-2 cells, are rapidly (4 h) transduced via PKC activation into up to sixfold increases in c-myc expression. This suggests the presence of a [Ca++]o-sensing membrane receptor (CaR) similar to that described by Brown et al. (1) in parathyroid and kidney cells. By RT-PCR we were able to amplify a 426 bp fragment from Caco-2 mRNA with 98% nucleotide identity to a part of the coding region for the extracellular domain of the parathyroid CaR. Immunohistochemical staining with a monoclonal antiparathyroid CaR antibody demonstrates CaR protein at the plasma membrane of confluent Caco-2 cells. Our results imply that the intestinal CaR is a potential mediator for the transduction of low luminal [Ca++]o into tumor promoting signals in human colonocytes.