bluuebunny/crossref_metadata_2025 huggingface dataset:
Campaign Finance Laws and Candidacy Decisions in State Legislative Elections
Authors: Hamm Keith E. , Hogan Robert E.
Published: March 2008

This article examines the influence of campaign election laws on patterns of candidacy in state legislative elections. Previous studies demonstrate that restrictions on campaign contributions affect levels of campaign spending and competition, but do such legal conditions influence the likelihood that incumbents running for reelection are even challenged? How important is this effect relative to other factors, such as ballot access laws and district political variables, in influencing rates of contestation in primary and general elections? Analyses of state- and district-level features in 1994, 1996, and 1998 show that low contribution limits increase challenger emergence in general elections.
At the Edge of Consciousness: Automatic Motor Activation and Voluntary Control
Authors: Sumner Petroc , Husain Masud
Published: March 2008

Conventionally, voluntary conscious acts and automatic behavior have been considered to be mediated by separate processes—and by separate brain structures. In this review, the authors consider the evidence that this might not be the case. First, they draw together disparate lines of evidence showing that visual stimuli cause automatic and unconscious motor activation. They briefly discuss the visual grasp reflex (automatic orienting of gaze to a salient visual stimulus), subliminal priming, and object affordances in healthy individuals. They also consider cases where inhibition of such reflexive behavior may be disrupted following brain lesions, as in patients demonstrating alien limb syndrome and utilization behavior. The authors argue that automatic motor activation forms an intrinsic part of all behavior, rather than being categorically different from voluntary actions. A crucial issue is how such automatic mechanisms are controlled so that the most appropriate responses are made and unwanted responses inhibited. The authors discuss some of the brain areas involved, including the supplementary motor area and the parietal cortex. Last, they review evidence that some control may actually be achieved by automatically triggered inhibition as well as modulation of unconscious processes by attention and task goals. NEUROSCIENTIST 14(5):474—486, 2008. DOI: 10.1177/1073858408314435
Implacably Hostile or Appropriately Protective?
Authors: Harrison Christine
Published: March 2008

The United Kingdom has seen conflicting developments in safeguarding women's and children's safety when there has been domestic violence. Although criminal justice responses have improved, child contact arrangements following parental separation remain dominated by pro-contact models that fail to take full account of the impact of domestic violence. Drawing on qualitative research in U.K. child contact (visitation) centers, this article presents women's perspectives to demonstrate how family court proceedings and welfare practices marginalized violence and exposed women and children to further abuse. This builds on previous articles in the journal to show how, in the post-separation family, contact now constitutes a significant site for continuing violence.
The Fathering of Violent Men
Authors: Perel Guy , Peled Einat
Published: March 2008

The study presented in this research note aims to expand our understanding of the experience of fathering for men who are violent toward their partners. The naturalistic qualitative methodology applied was shaped by phenomenological, feminist, and interpretative interactionist influences. In-depth interviews were conducted with 14 abusive men identified through domestic violence intervention centers. The findings describe the drama of fathering for abusive men, centered on an inner dialogue between an experienced constriction and a yearning for a closer, deeper connection with their children. The discussion focuses on the meaning of fathering for abusive men, and possible applications for intervention are proposed.
Risk Factors for Intimate Partner Violence Against Women in St. Petersburg, Russia
Authors: Stickley Andrew , Timofeeva Irina , Sparén Pär
Published: March 2008

This exploratory study examines which risk factors are associated with intimate partner violence against women in St. Petersburg, Russia. Women attending two crisis centers and a birthing house constituted the study sample. The male partner's frequent alcohol consumption and seeing his father hit his mother in childhood were associated with an increased risk of violence, whereas living in a communal apartment reduced the risk of intimate partner violence. The importance of crisis centers in Russia is highlighted by the study, as the women who turn to them are likely to have experienced more severe forms of violence.
Can the FCC Still Ignore the Public?
Authors: Brown Duncan H. , Blevins Jeffrey Layne
Published: March 2008

Recent events in the broadcast policy-making system of the United States Federal Communications Commission (FCC) have raised the question: can public voices effectively participate in the broadcast policy-making process? This paper examines the factors working against public involvement, as well as those that have made recent intervention possible, especially the growth of the internet and its ability to facilitate more public activity. The authors conducted private in-depth interviews with FCC Commissioner Michael Copps and former FCC Commissioner Nicholas Johnson to discuss their exceptional efforts to better involve the public in the policy-making process during their service with the agency. Our analysis shows that the factors facilitating greater public involvement have developed to the point where, at least sometimes, the public and civil society organizations can either block, or at least modify, the demands of entrenched corporate interests.
Lifestyle and the Risk of Cardiovascular Disease in Women: Is Physical Activity an Equal Opportunity Benefactor?
Authors: Zoeller Robert F.
Published: March 2008

Cardiovascular disease is the number one killer of women in the United States. It is estimated that 36.6% of women older than age 20 have some form of cardiovascular disease. In 2004, an estimated 459 100 women died from cardiovascular disease, more than 10 times the number of women who died from breast cancer that same year. Regular physical activity of moderate intensity, such as brisk walking, reduces the risk of cardiovascular disease and mortality in women. The benefits of more vigorous exercise are not clear, but the apparent lack of a dose-response relationship between exercise intensity and cardiovascular benefit may be the result of the design of many epidemiologic and interventional studies. Studies examining the benefits of greater cardiorespiratory fitness for women are limited, but the data suggest that they are similar to that of men. Women may require greater caloric expenditure than men for weight reduction, but this issue may be confounded by other variables such as caloric intake and spontaneous physical activity. The risk of cardiovascular disease associated with type 2 diabetes is much greater in women than in men. Regular physical activity and greater cardiorespiratory fitness are associated with a lower incidence and prevalence of type 2 diabetes in women. Greater cardiorespiratory fitness has also been found to be protective of the metabolic syndrome, but the benefit of physical activity is unclear. Limited evidence suggests that moderate-intensity activities can lower systolic blood pressure in women. There is a pressing need for more research into the health benefits of regular physical activity in women.
Neonatal bone marrow transplantation of ADA-deficient SCID mice results in immunologic reconstitution despite low levels of engraftment and an absence of selective donor T lymphoid expansion
Authors: Carbonaro Denise A. , Jin Xiangyang , Cotoi Daniel , Mi Tiejuan , Yu Xiao-Jin , Skelton Dianne C. , Dorey Frederick , Kellems Rodney E. , Blackburn Michael R. , Kohn Donald B.
Published: March 2008

Adenosine deaminase (ADA)–deficient severe combined immune deficiency (SCID) may be treated by allogeneic hematopoietic stem cell transplantation without prior cytoreductive conditioning, although the mechanism of immune reconstitution is unclear. We studied this process in a murine gene knockout model of ADA-deficient SCID. Newborn ADA-deficient pups received transplants of intravenous infusion of normal congenic bone marrow, without prior cytoreductive conditioning, which resulted in long-term survival, multisystem correction, and nearly normal lymphocyte numbers and mitogenic proliferative responses. Only 1% to 3% of lymphocytes and myeloid cells were of donor origin without a selective expansion of donor-derived lymphocytes; immune reconstitution was by endogenous, host-derived ADA-deficient lymphocytes. Preconditioning of neonates with 100 to 400 cGy of total body irradiation before normal donor marrow transplant increased the levels of engrafted donor cells in a radiation dose–dependent manner, but the chimerism levels were similar for lymphoid and myeloid cells. The absence of selective reconstitution by donor T lymphocytes in the ADA-deficient mice indicates that restoration of immune function occurred by rescue of endogenous ADA-deficient lymphocytes through cross-correction from the engrafted ADA-replete donor cells. Thus, ADA-deficient SCID is unique in its responses to nonmyeloablative bone marrow transplantation, which has implications for clinical bone marrow transplantation or gene therapy.
Improving the prediction of mRNA extremities in the parasitic protozoan Leishmania
Authors: Smith Martin , Blanchette Mathieu , Papadopoulou Barbara
Published: March 2008

Background

Leishmania and other members of the Trypanosomatidae family diverged early on in eukaryotic evolution and consequently display unique cellular properties. Their apparent lack of transcriptional regulation is compensated by complex post-transcriptional control mechanisms, including the processing of polycistronic transcripts by means of coupled trans-splicing and polyadenylation. Trans-splicing signals are often U-rich polypyrimidine (poly(Y)) tracts, which precede AG splice acceptor sites. However, as opposed to higher eukaryotes there is no consensus polyadenylation signal in trypanosomatid mRNAs.

Results

We refined a previously reported method to target 5' splice junctions by incorporating the pyrimidine content of query sequences into a scoring function. We also investigated a novel approach for predicting polyadenylation (poly(A)) sites in-silico, by comparing query sequences to polyadenylated expressed sequence tags (ESTs) using position-specific scanning matrices (PSSMs). An additional analysis of the distribution of putative splice junction to poly(A) distances helped to increase prediction rates by limiting the scanning range. These methods were able to simplify splice junction prediction without loss of precision and to increase polyadenylation site prediction from 22% to 47% within 100 nucleotides.

Conclusion

We propose a simplified trans-splicing prediction tool and a novel poly(A) prediction tool based on comparative sequence analysis. We discuss the impact of certain regions surrounding the poly(A) sites on prediction rates and contemplate correlating biological mechanisms. This work aims to sharpen the identification of potentially functional untranslated regions (UTRs) in a large-scale, comparative genomics framework.
Establishment of a new method for precisely determining the functions of individual mitochondrial genes, using Dictyostelium cells
Authors: Chida Junji , Amagai Aiko , Tanaka Masashi , Maeda Yasuo
Published: March 2008

Background

Disruption of mitochondrial genes may become a powerful tool for elucidating precisely the functions of individual mitochondrial genes. However, it is generally difficult to manipulate genetically mitochondrial genes, because 1) a mitochondrion is surrounded by inner and outer membranes, and 2) there are a large number of mtDNA copies in a single cell. This is the reason why we tried to establish a novel method for disrupting a certain mitochondrial gene (rps4), using Dictyostelium cells.

Results

Here, we have developed a new method for specifically disrupting a mitochondrial gene (rps4 ; ribosomal protein subunit S4), by a combination of homologous recombination and delivery of an appropriate restriction endonuclease (Sfo I) into mitochondria. First, mitochondrially targeted Sfo I whose expression is under control of the tetracycline (Tet)-regulated gene expression system was introduced into cells heteroplasmic with respect to the rps4 gene. Then, the heteroplasmic cells were produced by homologous recombination by use of the construct in which the unique Sfo I site and the 5'-half of the rps4 coding region were deleted not to be digested by Sfo I, and therefore their mitochondria have both the wild-type mtDNA and the mutant mtDNA with the disrupted rps4 gene. In response to removal of Tet from growth medium, Sfo I was selectively delivered into mitochondria and digested only the wild-type mtDNA but not the mutated rps4. Thus one can gain rps4-null cells with only the mutated mtDNA, under the Tet-minus condition.

Conclusion

The mitochondrial gene-disruption method presented here must be widely useful for precisely determining the functions of individual mitochondrial genes. This is the first report to demonstrate complete and specific mitochondrial gene disruption.
p53-Dependent Apoptosis in the Inhibition of Spermatogonial Differentiation in Juvenile Spermatogonial Depletion (Utp14bjsd) Mice
Authors: Shetty Gunapala , Shao Shan H. , Weng Connie C. Y.
Published: March 2008

In adult male mice homozygous for the juvenile spermatogonial depletion (Utp14bjsd) mutation in the Utp14b gene, type A spermatogonia proliferate, but in the presence of testosterone and at scrotal temperatures, these spermatogonia undergo apoptosis just before differentiation. In an attempt to delineate this apoptotic pathway in jsd mice and specifically address the roles of p53- and Fas ligand (FasL) /Fas receptor-mediated apoptosis, we produced jsd mice deficient in p53, Fas, or FasL. Already at the age of 5 wk, less degeneration of spermatogenesis was observed in p53-null-jsd mice than jsd single mutants, and in 8- or 12-wk-old mice, the percentage of seminiferous tubules showing differentiated germ cells [tubule differentiation index (TDI)] was 26–29% in the p53-null-jsd mice, compared with 2–4% in jsd mutants with normal p53. The TDI in jsd mice heterozygous for p53 showed an intermediate TDI of 8–13%. The increase in the differentiated tubules in double-mutant and p53 heterozygous jsd mice was mostly attributable to intermediate and type B spermatogonia; few spermatocytes were present. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling staining showed that most of these differentiated spermatogonia still underwent apoptosis, thereby blocking further continuation of spermatogenesis. In contrast, the percentage of tubules that were differentiated was not significantly altered in either adult Fas null-jsd mice or adult FasL defective gld-jsd double mutant mice as compared with jsd single mutants. Furthermore, caspase-9, but not caspase-8 was immunochemically localized in the adult jsd mice spermatogonia undergoing apoptosis. The results show that p53, but not FasL or Fas, is involved in the apoptosis of type A spermatogonia before/during differentiation in jsd mice that involves the intrinsic pathway of apoptosis. However, apoptosis in the later stages must be a p53-independent process.
Activation of Phosphatidylinositol 3-Kinase Signaling Promotes Aberrant Pituitary Growth in a Mouse Model of Thyroid-Stimulating Hormone-Secreting Pituitary Tumors
Authors: Lu Changxue , Willingham Mark C. , Furuya Fumihiko , Cheng Sheue-yann
Published: March 2008

TSH-secreting pituitary tumors (TSHomas) are pituitary tumors that constitutively secrete TSH. Molecular mechanisms underlying this abnormality are largely undefined. We recently created a knock-in mutant mouse harboring a mutation (denoted as PV) in the thyroid hormone receptor-β gene (TRβPV/PV mouse). As these mice age, they spontaneously develop TSHomas. Using this mouse model, we investigated the role of the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway in the pathogenesis of TSHomas. Concurrent with aberrant growth of pituitaries, AKT and its downstream effectors, mammalian target rapamycin and p70S6K, were activated to contribute to increased cell proliferation and pituitary growth. In addition, activation of AKT led to decreased apoptosis by inhibiting proapoptotic activity of Bcl-2-associated death promoter, further contributing to the aberrant cell proliferation. These results suggest an activated PI3K-AKT pathway could underscore tumorigenesis, raising the possibility that this pathway could be a potential therapeutic target in TSHomas. Indeed, TRβPV/PV mice treated with a PI3K-specific inhibitor, LY294002, showed a significant decrease in pituitary growth. The progrowth signaling via AKT-mammalian target rapamycin-p70S6K and cyclin D1/cyclin-dependent kinase were inhibited, and proapoptotic activity of Bcl-2-associated death promoter was increased by LY294002 treatment. Thus, activation of the PI3K-AKT pathway mediates, at least in part, the aberrant pituitary growth, and the intervention of this signaling pathway presents a novel therapeutic opportunity for TSHomas.
Changes to Gonadotropin-Releasing Hormone (GnRH) Receptor Extracellular Loops Differentially Affect GnRH Analog Binding and Activation: Evidence for Distinct Ligand-Stabilized Receptor Conformations
Authors: Pfleger Kevin D. G. , Pawson Adam J. , Millar Robert P.
Published: March 2008

GnRH and its structural variants bind to GnRH receptors from different species with different affinities and specificities. By investigating chimeric receptors that combine regions of mammalian and nonmammalian GnRH receptors, a greater understanding of how different domains influence ligand binding and receptor activation can be achieved. Using human-catfish and human-chicken chimeric receptors, we demonstrate the importance of extracellular loop conformation for ligand binding and agonist potency, providing further evidence for GnRH and GnRH II stabilization of distinct active receptor conformations. We demonstrate examples of GnRH receptor gain-of-function mutations that apparently improve agonist potency independently of affinity, implicating a role for extracellular loops in stabilizing the inactive receptor conformation. We also show that entire extracellular loop substitution can overcome the detrimental effects of localized mutations, thereby demonstrating the importance of considering the conformation of entire domains when drawing conclusions from point-mutation studies. Finally, we present evidence implicating the configuration of extracellular loops 2 and 3 in combination differentiating GnRH analog binding modes. Because there are two endogenous forms of GnRH ligand but only one functional form of full-length GnRH receptor in humans, understanding how GnRH and GnRH II can elicit distinct functional effects through the same receptor is likely to provide important insights into how these ligands can have differential effects in both physiological and pathological situations.
Cultured Murine Thyroid Epithelial Cells Expressing Transgenic Fas-Associated Death Domain-Like Interleukin-1β Converting Enzyme Inhibitory Protein Are Protected from Fas-Mediated Apoptosis
Authors: Fang Yujiang , Braley-Mullen Helen
Published: March 2008

The antiapoptotic molecule Fas-associated death domain-like IL-1β-converting enzyme inhibitory protein (FLIP) inhibits Fas-mediated apoptosis by blocking activation of caspase-8. We previously showed that expression of transgenic FLIP on thyroid epithelial cells (TECs) of DBA/1 and CBA/J mice promoted earlier resolution of granulomatous experimental autoimmune thyroiditis in vivo. This study was undertaken to directly determine whether transgenic FLIP expressed on cultured TECs can protect TECs from Fas-mediated apoptosis in vitro. The results indicate that cultured TECs from DBA/1 and CBA/J mice can be sensitized in vitro by interferon-γ and TNF-α to undergo Fas-mediated apoptosis. Transgenic overexpression of FLIP protected cultured TECs of FLIP transgene (Tg)+ DBA/1 and CBA/J mice from Fas-mediated apoptosis, and FLIP small interfering RNA transfection of cultured TECs of FLIP Tg+ DBA/1 and CBA/J mice abolished the protective effect. These in vitro results are consistent with our previous in vivo studies using DBA/1 and CBA/J FLIP Tg+ mice and provide direct support for the hypothesis that transgenic expression of FLIP promotes resolution of granulomatous experimental autoimmune thyroiditis by protecting TECs from apoptosis.
Nuclear and Extranuclear Estrogen Binding Sites in the Rat Forebrain and Autonomic Medullary Areas
Authors: Milner Teresa A. , Lubbers Laura S. , Alves Stephen E. , McEwen Bruce S.
Published: March 2008

Immunocytochemical studies have shown that nuclear and extranuclear estrogen receptors (ERs) are present in several extrahypothalamic brain regions. The goal of this study was to determine the subcellular location of functional ERs, particularly extranuclear ERs, by demonstrating 125I-estradiol binding in the rat forebrain and medullary sections prepared for light and electron microscopic autoradiography. Some sections were immunocytochemically labeled with the catecholamine-synthesizing enzyme, tyrosine hydroxylase (TH), prior to the autoradiographic procedure. By light microscopy, dense accumulations of silver grains denoting 125I-estradiol binding were observed over cells in the ventromedial and arcuate hypothalamic nuclei, amygdala, and nucleus of the solitary tract. In sections labeled for TH, large accumulations of silver grains were admixed with TH-labeled processes in the medial nucleus of the amygdala and over TH-labeled perikarya in the medial and commissural nucleus of the solitary tract. Electron microscopic analyses were focused on the rostral ventrolateral medulla and the hippocampal CA1 region, two regions previously shown to have extranuclear ERs. In the rostral ventrolateral medulla, silver grains indicative of 125I-estradiol binding were found within a few large terminals, affiliated with mitochondria. In the hippocampus, autoradiographic silver grains denoting 125I-estradiol binding were associated with mitochondria in dendritic shafts or were near synaptic specializations on dendritic spines. These patterns of silver grain labeling were not seen in sections from rats that received 125I-estradiol combined with cold estradiol. The association of 125I-estradiol binding with pre- and postsynaptic profiles supports a functional role for nonnuclear ERs in brain.
Semaphorin 3B Is a 1,25-Dihydroxyvitamin D3-Induced Gene in Osteoblasts that Promotes Osteoclastogenesis and Induces Osteopenia in Mice
Authors: Sutton Amelia L. M. , Zhang Xiaoxue , Dowd Diane R. , Kharode Yogendra P. , Komm Barry S. , MacDonald Paul N.
Published: March 2008

The vitamin D endocrine system is important for skeletal homeostasis. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] impacts bone indirectly by promoting intestinal absorption of calcium and phosphate and directly by acting on osteoblasts and osteoclasts. Despite the direct actions of 1,25(OH)2D3 in bone, relatively little is known of the mechanisms or target genes that are regulated by 1,25(OH)2D3 in skeletal cells. Here, we identify semaphorin 3B (SEMA3B) as a 1,25(OH)2D3-stimulated gene in osteoblastic cells. Northern analysis revealed strong induction of SEMA3B mRNA by 1,25(OH)2D3 in MG-63, ST-2, MC3T3, and primary osteoblastic cells. Moreover, differentiation of these osteogenic cells enhanced SEMA3B gene expression. Biological effects of SEMA3B in the skeletal system have not been reported. Here, we show that osteoblast-derived SEMA3B alters global skeletal homeostasis in intact animals and osteoblast function in cell culture. Osteoblast-targeted expression of SEMA3B in mice resulted in reduced bone mineral density and aberrant trabecular structure compared with nontransgenic littermates. Histomorphometry studies indicated that this was likely due to increased osteoclast numbers and activity. Indeed, primary osteoblasts obtained from SEMA3B transgenic mice stimulated osteoclastogenesis to a greater extent than nontransgenic osteoblasts. This study establishes that SEMA3B is a 1,25(OH)2D3-induced gene in osteoblasts and that osteoblast-derived SEMA3B impacts skeletal biology in vitro and in vivo. Collectively, these studies support a putative role for SEMA3B as an osteoblast protein that regulates bone mass and skeletal homeostasis.
The Thyroid Hormone-Inactivating Deiodinase Functions as a Homodimer
Authors: Sagar G. D. Vivek , Gereben Balázs , Callebaut Isabelle , Mornon Jean-Paul , Zeöld Anikó , Curcio-Morelli Cyntia , Harney John W. , Luongo Cristina , Mulcahey Michelle A. , Larsen P. Reed , Huang Stephen A. , Bianco Antonio C.
Published: March 2008

The type 3 deiodinase (D3) inactivates thyroid hormone action by catalyzing tissue-specific inner ring deiodination, predominantly during embryonic development. D3 has gained much attention as a player in the euthyroid sick syndrome, given its robust reactivation during injury and/or illness. Whereas much of the structure biology of the deiodinases is derived from studies with D2, a dimeric endoplasmic reticulum obligatory activating deiodinase, little is known about the holostructure of the plasma membrane resident D3, the deiodinase capable of thyroid hormone inactivation. Here we used fluorescence resonance energy transfer in live cells to demonstrate that D3 exists as homodimer. While D3 homodimerized in its native state, minor heterodimerization was also observed between D3:D1 and D3:D2 in intact cells, the significance of which remains elusive. Incubation with 0.5–1.2 m urea resulted in loss of D3 homodimerization as assessed by bioluminescence resonance energy transfer and a proportional loss of enzyme activity, to a maximum of approximately 50%. Protein modeling using a D2-based scaffold identified potential dimerization surfaces in the transmembrane and globular domains. Truncation of the transmembrane domain (ΔD3) abrogated dimerization and deiodinase activity except when coexpressed with full-length catalytically inactive deiodinase, thus assembled as ΔD3:D3 dimer; thus the D3 globular domain also exhibits dimerization surfaces. In conclusion, the inactivating deiodinase D3 exists as homo- or heterodimer in living intact cells, a feature that is critical for their catalytic activities.
The apical ectodermal ridge is a timer for generating distal limb progenitors
Authors: Lu Pengfei , Yu Ying , Perdue Yasmine , Werb Zena
Published: March 2008

The apical ectodermal ridge (AER) is a transient embryonic structure essential for the induction, patterning and outgrowth of the vertebrate limb. However, the mechanism of AER function in limb skeletal patterning has remained unclear. In this study, we genetically ablated the AER by conditionally removing FGFR2 function and found that distal limb development failed in mutant mice. We showed that FGFR2 promotes survival of AER cells and interacts with Wnt/β-catenin signaling during AER maintenance. Interestingly, cell proliferation and survival were not significantly reduced in the distal mesenchyme of mutant limb buds. We established Hoxa13expression as an early marker of distal limb progenitors and discovered a dynamic morphogenetic process of distal limb development. We found that premature AER loss in mutant limb buds delayed generation of autopod progenitors, which in turn failed to reach a threshold number required to form a normal autopod. Taken together, we have uncovered a novel mechanism, whereby the AER regulates the number of autopod progenitors by determining the onset of their generation.
Numerical investigation of the residual stresses in strength‐mismatched dissimilar steel butt welds
Authors: Lee C‐H , Chang K‐H
Published: March 2008

The presence of residual stresses in and around the welds can be detrimental to the performance of the welded part. Therefore, a good estimation of residual stresses in welds is needed. Simulation tools based on the finite element (FE) method are very useful to predict welding residual stresses. However, the numerical simulation of residual stresses in dissimilar steel welds is generally more challenging than that of residual stresses in similar steel welds because of the difference in the mechanical properties of the base metals to be joined and the weld metal strength mismatch which lies between two different base metals resulting from the use of weld metal fitted to either one. This paper presents the characteristics of residual stresses in strength‐mismatched dissimilar steel butt welds by carrying out three‐dimensional thermal elastic—plastic FE analysis, and the effects of weld metal strength on residual stress distributions are further investigated on the basis of the FE analysis results. Moreover, residual stresses in strength‐mismatched similar steel butt welds are examined for comparison.
Single‐point incremental forming and formability—failure diagrams
Authors: Silva M B , Skjoedt M , Atkins A G , Bay N , Martins P A F
Published: March 2008

In recent work, the present authors constructed a closed‐form analytical model that is capable of dealing with the fundamentals of single‐point incremental forming (SPIF) and explaining the experimental and numerical results published in the literature over the past couple of years. The model is based on membrane analysis with in‐plane contact frictional forces but is limited to plane strain, rotationally symmetric conditions.

The aim of the present paper is twofold: first, to extend the previous closed‐form analytical model into a theoretical framework that can easily be applied to the different modes of deformation that are commonly found in general single‐point incremental forming processes and, second, to investigate the formability limits of SPIF in terms of ductile damage mechanics and the question of whether necking does, or does not, precede fracture.

Experimentation by the present authors, together with data retrieved from the literature, confirms that the proposed theoretical framework is capable of successfully addressing the influence of the major parameters of the SPIF process. It is demonstrated that neck formation is suppressed in SPIF, so that traditional forming limit diagrams are inapplicable to describe failure. Instead fracture forming limit diagrams should be employed.
A reduced quasi—dimensional model to predict the effect of nozzle geometry on diesel engine performance and emissions
Authors: Jung D—H , Assanis D N
Published: March 2008

The predictive capability of the engine cycle simulation previously developed on the basis of a reduced quasi—dimensional combustion model has been enhanced by introducing a new submodel that correlates the discharge coefficient of the injector nozzle with the design variables of the nozzle and injection conditions. This enhancement enables prediction of the effect of microvariations in the injector nozzle hole geometry as well as the variations in the main design parameters on diesel spray evolution and combustion processes. As a result, the engine cycle simulation model can predict changes in engine performance and emissions due to injector nozzle design changes. First, the effect of the chamfer radius of the injector nozzle inlet on the discharge coefficient at various injection pressures was explored by simulating fuel injection in a constant—pressure vessel. The results showed that a larger chamfer radius improves the discharge coefficient and the rounded nozzle inlet can also reduce injector—to—injector variation. A case study of the injector nozzle hole design optimization was also performed for several different objectives to demonstrate the usage of the engine cycle simulation as a simulation tool. The case study showed that an optimized injector hole diameter depends on the objective while a larger chamfer radius, in general, helps to improve both engine performance and emissions.
Fault diagnostics in power electronics-based brake-by-wire systems
Authors: Masrur M A , Wu H-J , Mi C , Chen Z-H , Murphey Y L
Published: March 2008

A d.c.—motor—based brake—by—wire system is studied for the purpose of fault diagnostics of the power electronic switches. The voltage and current generated in the switching circuit under normal and six faulted conditions are observed. A hierarchical fuzzy diagnostic system has been developed to detect certain types of fault condition in any specific solid state power switch at the moment immediately after the occurrence of the fault. The hierarchical fuzzy diagnostic system has been tested and validated using data from both a simulation and a laboratory set—up with a 1 / 3 hp d.c. motor and a d.c.—to—d.c. converter. The system performance has been compared with two different fuzzy diagnostic systems and the results are presented. The hierarchical fuzzy diagnostic system trained on the simulated model has the capability of detecting certain types of fault condition occurring in a brake—by—wire actuator system set—up in a laboratory in less than 0.0009 s and pinpointing the specific types of fault within less than 0.013 s.
A novel pseudo—model following integral variable structure control for vision feedback autonomous mobile robots
Authors: Chuang C—W
Published: March 2008

The control of autonomous mobile robots is an important topic in the literature of intelligent robotics. With great progress in intelligent systems, mobile robots are often autonomously driven. The computer vision replaces the human eye to be the feedback component and, through image processing, the necessary information can be deciphered. However, owing to the complexity of the whole system, a mathematical model is usually not available. Hence, many model—based robust control rules cannot be applied to vision—guided autonomous mobile robots. At the same time, the calculation of image processing takes up a long time, from fetching the image to creating the image information. In order to solve these problems, this paper proposes a novel pseudo—model following integral variable structure control (PMF—IVSC). By the grey model (GM(1, 2)) method, i.e. the grey model with one output and two inputs, the plant and the reference model are converted into an accumulated model and a pseudo—reference model respectively. Applying the IVSC, the accumulated model is governed to follow the pseudo—reference model. The PMF—IVSC will successfully solve the unknown system's model following control. Finally, an experimental mobile robot is developed to examine the potential of the proposed control scheme. This paper carries out the vision—based experiment of automatically driving while lane following. The experimental results show that the proposed controller will eliminate the swinging phenomenon and increase the accuracy while tracking. The results also show the practical capability of the proposed rule in intelligent robotic systems.
A ramp—heated plate method for measuring heat and water vapour transport in seats
Authors: Ratts E B
Published: March 2008

In this paper, an experimental ramp method is presented which was used to quantify the capability of an automotive seat to move heat and moisture away from its surface. The method involved placing an indenter on a seat cushion for a fixed time period. Average heat and mass transfer rates were measured to compare seats. In addition, an effective effusivity was defined and measured to quantify the seat's thermal property.

The ramp method was used to compare the difference in dry ventilated and dry non—ventilated seats. An increase of 82 per cent in heat transfer was observed. The ventilated and non—ventilated seat effusivities were 440 W s1/2/m2 K and 292 W s1/2/m2 K respectively. In comparing wet ventilated with wet non—ventilated seats, an increase of 60–94 per cent in mass transfer was observed. Also, the method was used to compare the difference in positive—pressure and negative—pressure ventilation systems. The positive—pressure system demonstrated an increase over the negative—pressure system in dry heat transfer rate of 32 per cent. Both were comparable in terms of mass transfer capability.
A method for predicting dynamic behaviour characteristics of a vehicle using the screw theory — part 1
Authors: Lee U-K , Han C-S
Published: March 2008

This paper presents the development of a prediction method for vehicle dynamic behaviour characteristics using screw axis theory. A vehicle model is developed for quasi-static analysis which is applied to vehicles of three different suspension configurations under cornering conditions in which a specific lateral force acts. A finite screw axis is determined using quasi-static analysis based on a rigid body displacement of the vehicle model with respect to the ground. The fixed screw axis surface formed by the migration of the finite screw axis is also determined. The shape of the fixed screw surface shows that the fundamental characteristics of vehicle roll behaviour is determined not by suspension tuning element but by suspension geometry. The gradients of screw parameters with respect to lateral force when the vehicle model behaves in an initial cornering state are proposed as prediction parameters of vehicle dynamic motion. The dynamic analysis result shows that vehicle dynamic motion characteristics can be successfully predicted by the proposed parameters.
An optimal torque distribution strategy for an integrated starter—generator parallel hybrid electric vehicle based on fuzzy logic control
Authors: Zhong H , Wang F , Ao G-Q , Qiang J-X , Yang L , Zhuo B , Mao X-J
Published: March 2008

This paper presents a systemic design method of a multi-energy management control strategy by using fuzzy logic control to realize the optimal torque distribution between the internal combustion engine and electric motor. The controller which is the brain of the hybrid electric vehicle receives vehicle information such as the acceleration and brake pedal, the engine speed, and the absolute state of charge of the battery package as inputs and sends a direct torque command to control the electric motor and the engine throttle angle to command the diesel engine. Fuzzy control logic consists of three parts to realize the interpolation mechanism: the trapezoid membership, the Mamdani rule reference machine, and the centre of gravity as the defuzzification method. A novel technique to fuzzify the vehicle torque demand that can enable a point-to-point optimization is introduced and more than 130 rules are classified into four subrule bases. Hardware-in-the-loop simulation results reveal that the efficiency of the integrated starter—generator hybrid system has been improved greatly and the fuel economy is better than the default rule-based control strategy.
Thermodynamic analysis of the Stirling heat engine with regenerative losses and internal irreversibilities
Authors: Tlili I , Timoumi Y , Nasrallah S B
Published: March 2008

A model of an irreversible cycle of the Stirling heat engine, using air as the working substance, has been established. Several irreversibilities due to the non-adiabatic regenerator dead volumes of hot space, cold space, and regenerator that the regenerator effective temperature is an arithmetic mean of the heater and cooler temperature. In addition, the general irreversibilities of the non-quasistatic cycle are taken into account. Numerical simulation is performed and the effects of the regenerator effectiveness and dead volumes are studied. Some fundamental optimal relations and general performance characteristic curves of the cycle are obtained. The results from this study indicate that the engine net work is affected by the cycle irreversibilities, while the heat input and engine efficiency are affected by both the regenerator effectiveness and dead volumes. It is concluded that the system operating temperature and the overall system efficiency depend on the internal irreversibility of the heat engine.
A one-dimensional lean NOx trap model with a global kinetic mechanism that includes NH3 and N2O
Authors: Depcik C , Assanis D , Bevan K
Published: March 2008

Eaton has developed an aftertreatment system for medium- and heavy-duty diesel engines in response to the US 2010 regulations. This system consists of a fuel reformer, a lean NO x trap (LNT), and an ammonia selective catalytic reduction (SCR) catalyst in series. A transient, one-dimensional model of the system was developed to improve system performance, reduce experimental testing, and optimize system design. In this paper, the LNT portion of this model is presented. The model simulates flow, heat transfer, and chemical reactions in the LNT catalyst. A global LNT chemical kinetic mechanism was developed to simulate the key catalytic processes with the minimum number of reactions. The model can be used to predict LNT catalyst performance over a range of operating conditions and driving cycles.

Simulated species concentrations and gas temperatures at the LNT outlet were compared with experimental data at three steady state engine conditions over a 13-mode test. The conditions were chosen to develop and test the model over a range of gas temperatures, space velocities, and species concentrations. The LNT model predicts species trends and magnitudes with reasonable accuracy in comparison with experimental data. The simulated LNT NO x conversion efficiency over the 13-mode test was 67 per cent, compared with 63 per cent for the experiment.
Unsteady wall heat flux in spark-ignited, homogeneous charge engines fuelled with reformer gas/gasoline blends
Authors: Conte E , Boulouchos K
Published: March 2008

On-board partial oxidation of gasoline to produce reformer gas seems to be an attractive strategy to abate pollutant emissions from internal combustion engines. The engine behaviour in terms of efficiency and combustion process can be better understood by means of in-cylinder heat flux measurements. The study of the unsteady wall heat transfer, supported by previous studies of flame propagation and flame speed through ion sensors and optical fibres, reveals a limited influence of the reformer gas upon the heat transfer coefficient and possibly upon the flame-quenching distance, which is estimated in three different and independent ways.

A detailed statistical analysis of single-cycle heat flux shows that the cycle-to-cycle variation remains large when the fraction of reformer gas in the fuel blend increases, even if the global engine stability improves. The comparison of numerous data shows how the chemical energy is released partly within the flame and partly within the post-flame region. This last can account for as much as 30 per cent of the total energy release. The analysis of slow and fast-burning cycles with different fuel blends shows that this fraction of energy is released only when, during the expansion stroke, the cylinder temperature decreases below a certain threshold, allowing radicals to recombine and carbon monoxide (CO) completely to oxidize to CO 2.
Improvement of combustion and emissions in diesel engines by means of enhanced mixture formation based on flash boiling of mixed fuel
Authors: Senda J , Wada Y , Kawano D , Fujimoto H
Published: March 2008

A novel approach to reduce diesel engine emissions at relatively low injection pressures is proposed. This approach is based on the use of a mixed fuel where an additive or a low boiling point fuel such as CO2, gas fuel, or gasoline is mixed with a higher boiling point fuel such as diesel gas oil. When producing such a fuel, the vapour—liquid equilibrium in the two-phase region where the liquid and vapour phases of both components coexist is taken into account. In designing a mixed fuel, the authors intend to control both the physical process in the spray such as fuel evaporation and vapour air mixing and the chemical processes including spontaneous ignition and with reactions with regard to NO x, particulate matter (PM), and hydrocarbon (HC) formation. In this study flash boiling of mixed fuel is particularly focused on enhancing the mixing process in the spray because it has the potential to achieve fast evaporation and relatively lean and homogeneous mixtures. Experiments were carried out using two types of mixed fuel, both of which can generate flash boiling during injection events. In an experiment using a rapid compression machine (RCM) and an optical engine, mixed fuels consisting of liquefied CO2 as an additive and n-tridecane representing gas oil were employed with the aim of simultaneously reducting soot and NO x emissions. The high-speed images acquired for sprays reacting in the RCM and the engine clearly showed a significant reduction of soot formation in the spray. Reductions of soot and NO x emissions as well as the fuel consumption were also confirmed by emission measurements and a combustion analysis respectively. In other experiments, different types of mixed fuel consisting of gas or gasoline and gas oil were tested to see the effects on both the evaporation and ignition processes. The result of an engine experiment showed marked reductions of soot and HC emissions and fuel consumption.
Pollutant formation modelling in natural gas SI engines using a level set based flamelet model
Authors: Dahms R , Peters N , Stanton D W , Tan Z , Ewald J
Published: March 2008

The level set flamelet model for turbulent premixed combustion was recently extended to improve the modelling of the spark ignition process, to incorporate the influence of unsteady flame kernel development on turbulent flame propagation, to embrace flame—wall interaction, and to comprise pollutant prediction models. The formation of nitrogen oxides (NO x) is predicted using the extended Zeldovich mechanism. The concentrations of the involved intermediate species are determined using a chemical equilibrium assumption. The formation of engine-out unburnt hydrocarbons (UHCs) and carbon monoxides (COs) is directly linked to incomplete combustion due to flame quenching at the time the flame hits the wall.

In this paper, the new model is used for the analysis of combustion in a homogeneous charged natural gas SI engine operating on lean conditions. The investigated engine operating (PAM) points differ in the applied equivalence ratio, ignition timing, and rate of exhaust gas recirculation. The influence of the load on the peak pressures, peak pressure locations, and pollutant formations is discussed in detail. A good agreement with experimental data was obtained among all engine operating points.