bluuebunny/crossref_metadata_2025 huggingface dataset:
Principles of canonical action research
Authors: Davison Robert , Martinsons Maris G. , Kock Ned
Published: January 2004

Abstract.  Despite the growing prominence of canonical action research (CAR) in the information systems discipline, a paucity of methodological guidance continues to hamper those conducting and evaluating such studies. This article elicits a set of five principles and associated criteria to help assure both the rigor and the relevance of CAR in information systems. The first principle relates to the development of an agreement that facilitates collaboration between the action researcher and the client. The second principle is based upon a cyclical process model for action research that consists of five stages: diagnosis, planning, intervention, evaluation and reflection. Additional principles highlight the critical roles of theory, change through action, and the specification of learning in terms of implications for both research and practice. The five principles are illustrated through the analysis of one recently published CAR study.
Self‐inflicted orodental injury in a child with Leigh disease
Authors: Diab M.
Published: January 2004

Leigh disease is an inherited progressive mitochondrial neurodegenerative disease that affects the neurological, respiratory and cardiovascular systems and is associated with retardation of the intellectual and physical development. This report describes the case of a 4‐year‐old boy with Leigh disease who presented with self‐inflicted traumatic injury to the teeth, alveolar bone, lips and tongue during repeated episodes of intense orofacial spasms. Conservative management of the injury included repositioning the fractured alveolar bone, splinting the traumatized teeth and planning for a mouthguard. However, after a second incident of severe self‐induced injury to the teeth and alveolar bone, extraction of the anterior teeth became inevitable to protect the child from further self‐mutilation and to allow healing of the injured tissues.
Early craniofacial signs of cleidocranial dysplasia
Authors: Golan I. , Baumert U. , Hrala B. P. , MÜßIg D.
Published: January 2004

Objectives.  Early diagnosis of CCD is essential for a timely introduction of the appropriate treatment approach. Since certain symptoms first fully manifest only during the pubertal growth spurt, their indicatory signs are often overlooked. The aim of this study is to describe the initial craniofacial findings in patients with CCD in order to categorise their reliability for early detection.

Method.  14 patients with CCD between the ages of 6 and 11 years who were referred to the University of Regensburg over a 4‐year period were included in this study. The patients were examined clinically and radiologically and their dental status was determined. Typical signs of CCD were analysed according to such classic criteria as the ‘quatermoon’‐physiognomy described in the literature. The clinical findings were compared to medical data and case history.

Results.  Early signs were registered for each patient. While some signs could be found in all patients, others were variably expressed. The typical extraoral symptoms were only rarely exhibited in our patient population.

Conclusion.  As various indicators of CCD are age related, their expression should be taken into account for early diagnosis. Apparent signs only manifest during the growth spurt when the ideal timeframe for beginning treatment has already past. The symptoms described should serve as early markers to aid the general and paediatric dentist in planning appropriate treatment or referring patients to specialised centres.
Dental treatment needs of children in a rural subcounty of Uganda
Authors: Nalweyiso N. , Busingye J. , Whitworth J. , Robinson P. G.
Published: January 2004

Objectives.  To describe normative dental treatment needs of 5–7 and 12‐year‐olds in a rural sub county of Uganda and devise a strategy to improve oral health.

Design.  Clinical survey.

Setting.  Primary schools in the subcounty.

Sample and methods.  School‐based random cluster sample of 236 5–7‐year‐olds and 202 12‐year‐olds. Dental status and treatment need data were collected according to WHO Oral Health Surveys Basic Methods. Additional data for 12‐year‐olds included dental fluorosis using the Thylstrup and Fejerskov index (TFI), oral hygiene procedures and experience of oral pain in the previous month.

Results.  In the 5–7‐year‐olds, mean dmft was 1·47 (50·8% dmft = 0). A total of 52·5% needed fillings and almost one third needed a tooth extracted. Among the 12‐year‐olds, mean DMFT was 0·64 (65·8% DMFT = 0), 28·5% had dental fluorosis and 6·7% had TFI > 2. Toothache in the previous four weeks was reported by 36·5%, 30·2% needed a filling and 6·4% needed one or more teeth extracted.

Conclusions.  Dental disease is a significant public health problem in this population. An efficient way to meet the needs of the children would be to increase the availability of fluoride toothpaste and to develop a service to provide treatment using Atraumatic Restorative Technique.
Factors related to severe untreated tooth decay in rural adolescents: a case‐control study for public health planning
Authors: Skaret E. , Weinstein P. , Milgrom P. , Kaakko T. , Getz T.
Published: January 2004

Objectives.  In this case‐control study of rural adolescents we identified factors to discriminate those who have high levels of tooth decay and receive treatment from those with similar levels who receive no treatment.

Methods.  The sample was drawn from all 12–20‐year‐olds (n = 439) in a rural high school in Washington State, U.S. The criterion for being included was 5 or more decayed, missing or filled teeth. The questionnaire included structure, history, cognition and expectation variables based on a model by Grembowski, Andersen and Chen.

Results.  No structural variable was related to the dependent variable. Two of 10 history variables were related: perceived poor own dental health and perceived poor mother's dental health. Four of eight cognition variables were also predictive: negative beliefs about the dentist, not planning to go to a dentist even if having severe problems, not being in any club or playing on a sports team and not having a best friend. No relationship was found for the expectation variable ‘usual source of care’.

Conclusions.  These data are consistent with the hypothesis that untreated tooth decay is associated with avoidance of care and point to the importance of history and cognition variables in planning efforts to improve oral health of rural adolescents.
Osteosarcoma of the jaws in children
Authors: Donaldson M. E. , Geist J. R. , Daley T. D.
Published: January 2004

Summary.  Two cases of osteosarcoma of the jaws in children are reported. One patient was a 13‐year‐old girl whose first symptoms included nasal and maxillary sinus congestion, followed by epistaxis. She was found to have chondroblastic osteosarcoma extending through the left maxillary alveolar process and sinus. Following surgery and chemotherapy, the patient has been free of disease for 7 years. The second patient, an 8‐year‐old boy, was diagnosed with juxtacortical (parosteal) osteosarcoma of the mandible, which is a less aggressive variant of the neoplasm. It is believed that this is the youngest patient reported to date with juxtacortical osteosarcoma of the jaws. He was treated by block resection of the right side of the mandible and is free of disease 3½ years later.
Morbidity following dental treatment of children under intubation general anaesthesia in a day‐stay unit
Authors: Atan S. , Ashley P. , Gilthorpe M. S. , Scheer B. , Mason C. , Roberts G.
Published: January 2004

Objectives.  To determine which variables were best related to the overall morbidity of a child undergoing dental general anaesthetic (GA) and then to use these variables to determine those factors that might influence the extent and severity of morbidity experienced by healthy children following dental GA.

Sample and methods.  Data were collected on anxiety, pain and morbidity, GA procedure and dental procedure from 121 children attending a day stay GA unit for dental treatment. Patients were interviewed preoperatively, postoperatively before discharge then four further times over the next 148 h. Data were analysed using multivariate regression.

Results.  Thirty‐one per cent of subjects had restorative work, 60% had at least one tooth extracted, 54% had a surgical procedure. Use of local analgesia reduced postoperative pain whilst an increase in the number of surgical procedures increased it. Increase in anaesthetic time was related to increased odds of feeling sleepy and nauseous, females were more likely to complain of sleepiness or weakness. Feelings of dizziness were increased if the patient was given local analgesia during the procedure.

Conclusions.  Pain following dental GA was the most prevalent and long lasting symptom of postoperative morbidity in this study. Reductions in operating time and improvement in pain control have the potential to reduce reported morbidity following dental GA.
MD‐1 expression regulates direct and indirect allorecognition
Authors: Hadidi S. , Gorczynski R.M.
Published: January 2004

Abstract:  Expression of the molecule MD‐1 was previously described to regulate allogeneic and xenogeneic skin graft survival, as documented by the decrease in rejection seen following functional blockade of MD‐1 expression in vivo, using antisense oligodeoxynucleotides (ODNs) or anti‐MD‐1 antibodies. It was unclear from these data whether blockade of expression of MD‐1 on donor or recipient cells was crucial. We have investigated the effect on allorecognition of treating skin graft donors, and/or recipients, of either fully major histocompatibility complex (MHC)‐mismatched allogeneic skin grafts (C3H with C57BL/6 grafts and vice versa) or grafts differing at only multiple minor alloantigens (C3H with B10.BR grafts; C57BL/6 with C3H.SW), with antisense ODNs to MD‐1, or in some cases, following transplantation of class II‐deficient cells into class I‐deficient mice. Graft‐specific cytotoxic T lymphocytes (CTLs) were measured in spleen cells recovered at sacrifice of recipients and following donor‐specific restimulation in vitro. In the latter case, we also measured cell proliferation and (by enzyme‐linked immunosorbent assay) production of interleukin‐2 (IL‐2)/interferon‐γ (IFN‐γ) or IL‐4/IL‐10 in vitro (nominal type‐1 vs type‐2 cytokines). CTL responses to minor‐incompatible grafts were diminished, only if graft recipients were treated with ODNs. However, treatment of graft donor and/or recipient of MHC‐incompatible grafts produced inhibition of CTL production. Optimal inhibition came from treating both. Specific suppression of CTL production coincided with inhibition of proliferation and preferential production of IL‐4 and IL‐10 at the expense of IL‐2 and IFN‐γ. Our data are consistent with the hypothesis that MD‐1 expression regulates both the direct and indirect pathways of allorecognition and that regulation of MD‐1 expression may thus help regulate clinical graft rejection.
Identification of a novel HLA‐F allele – HLA‐F*010102
Authors: He X. , Xu L. , Liu Y. , Zeng Y.
Published: January 2004

Abstract:  We describe herein the identification of HLA‐F*010102 by cloning the full‐length coding sequence with reverse‐transcription polymerase chain reaction (RT‐PCR). This new allele was found in two Han Chinese individuals in the course of cloning major histocompatibility complex class Ib (MHC Ib) cDNA. It was identical to HLA‐F*010101 except for a single‐nucleotide substitution in codon −1 (GCG → GCA). This nucleotide change represents a synonymous mutation, as both triplets code for an alanine. The cDNA of this allele was 48 bp shorter than HLA‐F*010101 due to splicing out exon 7. Analysis of the deduced amino acid sequence revealed that the product of this new allele had the identical extracellular domain and transmembrane region but had a shorter cytoplasmic tail.
Molecular characterization of guinea ‐ pig (Cavia porcellus) CD8α and CD8β cDNA
Authors: Nagarajan U.M. , O'Connell C. , Rank R.G.
Published: January 2004

Abstract:  CD8 is expressed on cytotoxic T cells (CTL) and functions as a coreceptor for recognition of major histocompatibility complex (MHC) class I peptide complexes by the T‐cell receptor (TCR). The CD8 molecule consists of two subunits (α and β) and exists either as a heterodimer (αβ) or a homodimer (αα). We report the cloning of full‐length cDNAs of guinea pig CD8α and CD8β. The deduced amino acid sequence of CD8α and CD8β reveals characteristic structural features including a signal peptide, an immunoglobulin (Ig) variable‐like region, hinge region, transmembrane, and cytoplasmic domains. In addition to the full‐length cDNA, a splice variant of CD8β cDNA was observed, suggesting splicing events as reported for human CD8β. The sequence homology of guinea pig CD8 indicates greater homology to human, canine, and feline counterparts than to rodent CD8. As the guinea pig serves as an ideal non‐primate animal model to several human infectious diseases, such as syphilis, tuberculosis, and chlamydial genital and ocular infection, the CD8 sequence information provides a necessary molecular tool for studying the cell‐mediated immune response.
Human leukocyte antigen‐A, ‐B, and ‐Cw polymorphism in a Berber population from North Morocco using sequence‐based typing
Authors: Piancatelli D. , Canossi A. , Aureli A. , Oumhani K. , Del Beato T. , Di Rocco M. , Liberatore G. , Tessitore A. , Witter K. , El Aouad R. , Adorno D.
Published: January 2004

Abstract:  Class I human leukocyte antigen (HLA) polymorphism was examined in a Berber population from North Morocco, named Metalsa (ME). All data were obtained at high‐resolution level, using sequence‐based typing. The most frequent alleles were: HLA‐A*0201 and A*0101; HLA‐B*44 (B*4403 and B*4402); B*0801 and the B*50 allele group (B*5001 and B*5002); HLA‐Cw*0602; and Cw*07 group (Cw*070101, Cw*070102, Cw*0702, Cw*0704, and Cw*0706), and Cw*040101. The novel HLA‐B*570302 allele was identified. It differs at position 486 and position 855 from B*570301, resulting in synonymous Thr and Val. The analysis also evidenced some alleles common in Africans (A*3402, A*6802, A*7401, B*1503, B*4102, B*4202, B*7801, B*5802, Cw*1701, and Cw*1703) and some uncommon alleles (A*3004, B*2702, B*2703, B*5001,02, B*3503, and Cw*0706). The predominant HLA‐A‐Cw‐B‐DRB1‐extended haplotypes in ME population were A*0101‐Cw*0501‐B*4402‐DRB1*0402, A*240201‐Cw*0701‐B*0801‐DRB1*030101, A*2301‐Cw*040101‐B*4403‐DRB1*040501, A*0201‐Cw*040101‐B*4403‐DRB1*1302, and A*3002‐Cw*0602‐B*5002‐DRB1*0406. This study demonstrates a strong relatedness of ME to other Moroccan and North African populations, some characteristics of sub‐Saharan Africans and evidenced the influence of various immigrations during centuries. Nevertheless, this study highlights some unique genetic traits of the ME population compared to other ethnic groups within Morocco, which could be of great interest for clinical aims, transplantation, and diseases.
The phylogenies of introns 4–7 demonstrate an inconsistent pattern between human leukocyte antigen‐C group topologies
Authors: Elsner H.‐A. , Blasczyk R.
Published: January 2004

Abstract:  In this study, we have sequenced introns 4–7 in 31 human leukocyte antigen‐C (HLA‐C) alleles representing all allelic groups. Intron sequences show a patchwork pattern of polymorphism. Bootstrap support for phylogenetic lineages and for differentiation between groups is limited due to the high homology of intron sequences, where the substitution of a single nucleotide may lead to the assignment to different clusters. The intron data suggest the idea of a Cw*06/Cw*12 family, which is closely related to a hypothetical Cw*05/Cw*08 family. Moreover, a third family consisting of Cw*01/Cw*04/Cw*18 may exist. The intron data compiled in our study may be the basis for further sequencing studies. The detection of three novel alleles (Cw*0401new, Cw*140201new, and Cw*1701new) suggests that the HLA‐C polymorphism might have been strongly underestimated to date.
Cloning of a human antibody directed against human neuroblastoma cells and specific for human translation elongation factor 1α
Authors: Schilbach K. , Kreyenberg H. , Geiselhart A. , Niethammer D. , Handgretinger R.
Published: January 2004

Abstract:  Human sera have shown antitumor effects mediated by tumor‐specific immunoglobulin M (IgM) antibodies. Most people who have cytotoxic serum are in good health and show no evidence of exposure to tumor antigens. We characterized the serum of a healthy female adult that was highly lytic to a neuroblastoma cell line via IgM‐activated complement (>60% of malignant cells were killed during the 60‐min assay). Complement‐dependent lysis was not mediated by other classes of serum antibodies (data not shown) which is consistent with the findings of Ollert et al. To identify the target antigen on neuroblastoma cells, we fractionated neuroblastoma cell lysates by ion‐exchange chromatography. In the fraction that showed maximal IgM binding, the dominant protein was identified as the 47‐kDa translational elongation factor 1α (eEF1α). We used the donor's B‐cells to create hybridomas producing the antibody (B12.6.22) that bound to neuroblastoma cells and mediated cytotoxicity. This antibody recognized eEF1α in a specific manner. Sequence analysis of the heavy chain of B12.6.22 showed usage of VH3‐23 and JH6 gene segments, with no somatic mutation. The structural similarity of B12.6.22 to antibodies of the innate immune system supports the assumption that natural antibodies are a potential source of therapeutic antibodies.
Chromatin‐associated HMG1, HMGI/Y and SSRP1 proteins of higher plants
Authors: Grasser Klaus D. , Krohn Nicholas M. , Lichota Jacek , Stemmer Christian
Published: January 2004

Many DNA transactions such as transcription and recombination are regulated by the formation of specific higher‐order nucleoprotein structures. Multiple protein/DNA and protein/protein interactions act synergistically to provide the precision required for the regulation of these processes. The assembly of the nucleoprotein complexes often requires that the DNA is specifically folded by DNA‐bending proteins. In plants, various chromatin‐associated high mobility group (HMG) proteins of the HMG1 and HMGI/Y families have been identified which have the potential to act as architectural factors that modulate DNA structure. In addition, by protein/protein‐contacts these proteins assist the binding of regulatory factors to their cognate DNA sites. Therefore, the HMG1 and HMGI/Y proteins might be involved as architectural factors in the regulation of various biological processes.
Illumination does not affect the membrane potential or the plasma membrane H+‐ATPase activity in Micrasterias
Authors: Lehtonen Juhani , Saari Jussi
Published: January 2004

The membrane potential (MP) of the unicellular green alga Micrasterias torreyi was found to be −46 to −47 mV (when cultured in Waris medium). In contrast to plant cells in general, light‐dark changes neither affected the potential or the membrane resistance in Micrasterias. In comparison, the freshwater plant Elodea showed a light‐induced hyperpolarization due to the activating effect of light on the plasma membrane adenosine triphosphatases (PM ATPases) through a signal from chloroplasts. In Micrasterias, the PM H+‐ATPase inhibitors Na‐orthovanadate and diethylstilbestrol depolarized the potential, but it remained at the same level in light and dark. On the other hand, fusicoccin, which activates the PM H+‐ATPases, hyperpolarized the potential clearly (to −56 mV). 3‐(3′,4′‐dichlorophenyl)‐1,1‐dimethylurea, which blocks the electron transport chain from photosystem (PS)II to PSI and thereby prevents the possible signal transmission from chloroplasts to the PM, depolarized the MP slightly, but did not affect the (lacking) light changes either. The results indicate the presence of a continuous (low) activity of PM H+‐ATPases in Micrasterias, which is not stimulated by light. The lack of rapid light‐induced changes in Micrasterias MP may be due to an unusual functioning of giant chloroplasts in the ion metabolism of the Micrasterias cell.
Lipid lateral diffusion and local microviscosity in plant mitochondrial membranes with various length and unsaturation of fatty acids
Authors: Cantrel Catherine , Caiveau Olivier , Moreau François , Zachowski Alain
Published: January 2004

Two main aspects of the lipid dynamics, local microviscosity and lateral diffusion, were investigated in intact plant mitochondria isolated from different tissues exhibiting large differences in their fatty acids in terms of unsaturation (amount of linoleic and linolenic acids) or length of the hydrocarbon chains. In addition, the same parameters were determined in the outer and inner membranes isolated from cauliflower mitochondria, which differed not only in the fatty acid composition but also by the lipid‐to‐protein ratio. In intact mitochondria, local microviscosity assayed with anthroyloxy‐fatty acids exhibited a transverse gradient from the surface to the center of the bilayer, which was mainly affected by the unsaturation index and the content in linoleic or linolenic acids. In contrast, lipid lateral diffusion increased as the content in linolenic or palmitic acids increased, but was not directly correlated to the unsaturation index. Interestingly, local microviscosity at the membrane surface was higher in the outer membrane than in the inner membrane, whereas no significant difference was found in lipid lateral diffusion. These results indicate that the influence of the fatty acid composition of mitochondrial membranes on the dynamics of the phospholipid bilayer depends on the type of movement considered and suggest that other parameters, such as the protein content of the bilayer, also affect membrane fluidity.
Biosynthesis of phytoalexin in carrot root requires ethylene action
Authors: Fan Xuetong , Mattheis James P. , Roberts Rodney G.
Published: January 2004

The role of ethylene in phytoalexin production by carrot (Daucus carota L.) roots was investigated using the ethylene action inhibitor 1‐methylcyclopropene (MCP). Exposure of carrot roots to ethylene, UV‐B irradiation, inoculation with fungal pathogens, treatment with 2,4‐D or methyl jasmonate induced accumulation of the phytoalexin 6‐methoxymellin (6‐ME). Exposure to MCP for 4–12 h prior to the treatments completely inhibited 6‐ME accumulation, indicating that 6‐ME synthesis by carrot roots requires ethylene action.
Basal leaf senescence in a sunflower (Helianthus annuus) canopy: responses to increased R/FR ratio
Authors: Rousseaux M. Cecilia , Hall Antonio J. , Sánchez Rodolfo A.
Published: January 2004

Senescence of lower leaves (LS) begins before anthesis in sunflower crop canopies. Using isolated field‐grown sunflower plants, it has previously been shown that pre‐anthesis LS is dependent on photosynthetic photon flux density (PPFD) and is hastened by increases in far‐red light. We tested the hypothesis that increasing the red/far‐red ratio (R/FR) perceived by basal leaves within canopies delays LS. To do this, light impinging on the lower surface of north‐oriented 8th leaves (cotyledons=0) of crops with maximum leaf area indexes of 3.3 (Experiment 1) and 2.4 (Experiment 2) was enriched (+8.33 μmol m−2 s−1) with red light using light emitting diode (LED) panels. LED panels constructed with unlit LED or with green LED (PPFD slightly greater than the red LED panels, to compensate for lower efficiency) were used as controls. Compared with controls, additional R significantly (P<0.05) increased R/FR perceived by the lower surface and significantly (P<0.01) delayed LS. On average, leaf duration, as time between full expansion and a 70% diminution of chlorophyll content, was 5 days greater for leaves receiving extra red light (maximum observed LD=27 days). We conclude that an increase in the R/FR ratio can delay LS in crop canopies.
Exchange of oxygen and its role in energy dissipation during drought stress in tomato plants
Authors: Haupt‐Herting Silke , Fck Heinrich P.
Published: January 2004

To elucidate how excess light energy is dissipated during water deficit, net photosynthesis (PN), stomatal conductance (gs), intercellular CO2 concentration (ci) and Chl a fluorescence were investigated in control and drought‐stressed tomato plants (Lycopersicon esculentum). Gross O2 evolution (Eo) and gross O2 uptake (Uo) were determined by a mass spectrometric 16O/18O2 isotope technique. Under drought stress PN, gs, ci and Uo decline. While photochemical fluorescence quenching decreases under water deficit, non‐photochemical quenching rises. The maximal efficiency of PSII measured in the dark is not affected by drought; however, in the light, Eo decreases under water deficit. The ratio PN/Eo falls under stress while the ratio Uo/Eo increases. We conclude that tomato plants follow a double strategy to avoid photodamage under drought stress conditions: (1) a substantial portion of light energy is emitted as heat and PSII activity is downregulated. This results in a decrease in Eo as well as PN and Uo. Despite reduced charge separation at PSII, the decline of CO2 assimilation because of lowered stomatal conductance and metabolic changes results in the need of degrading excessive photosynthetic electrons. (2) Oxygen is used as an alternative electron acceptor in photorespiration or Mehler reaction and Uo rises relative to Eo.
Aphid infestation induces PR‐proteins differently in barley susceptible or resistant to the birdcherry‐oat aphid (Rhopalosiphum padi)
Authors: Forslund Karin , Pettersson Jan , Bryngelsson Tomas , Jonsson Lisbeth
Published: January 2004

The effect of infestation by the birdcherry‐oat aphid (Rhopalosiphum padi L.), on induction of PR‐proteins was investigated in barley (Hordeum vulgare L.), using barley lines susceptible or resistant to R. padi. The PR‐proteins PR‐1a (unknown function), PR‐5a (acidic thaumatin) and peroxidase (EC 1.11.1.7) were not affected, whereas one chitinase (EC 3.2.1.14) and 4 β‐1,3‐glucanases (EC 3.2.1.39) were induced by the aphid treatment. In the resistant breeding line CI 16145, but not in the susceptible cultivar Golf, accumulation of one basic chitinase and two acidic β‐1,3‐glucanases increased with time from 2 until 11 days after infestation, as determined by western blots, with antibodies raised against purified chitinase (PR‐3a) and β‐1,3‐glucanase (PR‐2a) from barley. By isoelectric focusing, two additional basic β‐1,3‐glucanases were detected, which increased after infestation in both the resistant and the susceptible barley. The basic chitinase was only detected at days 7 and 11 in the susceptible cultivar, but already at day 2 in the resistant line. The induction was localized to the infested leaf. The PR‐proteins PR‐3a and PR‐2a were also induced by the fungal pathogen (Blumeria [syn. Erysiphe] graminis f. sp. hordei), methyl salicylate and, to a lower extent, by wounding with tweezers and methyl jasmonate (MeJA). Needle wounding performed to mimic aphid stylet penetration did not induce chitinase or β‐1,3‐glucanase. It is concluded that the fungal pathogen and the aphid infestation induce both similar and different responses, and that the aphid induction is not due to wounding only. The different responses in resistant and susceptible lines indicate that the induced enzymes may play a role in the resistance against aphid infestation.
Carbon partitioning and sucrose metabolism in tomato plants growing under salinity
Authors: Balibrea María E. , Dell'Amico José , Bolarín Maríaa C. , Pérez‐Alfocea Francisco
Published: January 2004

The different growth responses under salinity in relation to the carbon partitioning and sucrose metabolism in both sink and source organs have been studied in a salt‐tolerant (cv. Pera) and in a salt‐sensitive (cv. Volgogradskij) tomato genotype (Lycopersicon esculentum Mill.). After 3 weeks of salinization, the plant dry weight was reduced by 12–34% in cv. Pera and by 45–58% in cv. Volgogradskij. Photosynthesis was positively correlated to plant growth in cv. Pera but not in cv. Volgogradskij. In this salt‐sensitive genotype, both photosynthesis and growth were negatively correlated with fructose, glucose and sucrose accumulation in both mature and young leaves, suggesting a blockage in their use for growth. The transient accumulation of sucrose and hexoses in the young leaves of cv. Pera was linked to increases in all soluble sucrolytic activities, mainly acid invertase (EC 3.2.1.25) and sucrose synthase (EC 2.4.1.13), which was related to sink activity and growth capacity. The sucrose‐phosphate synthase activity (EC 2.4.1.14) was related to the ability of mature leaves to regulate assimilate production, accumulation and export. The salt‐tolerant cv. Pera accumulated a higher amount of total carbohydrates, but cv. Volgogradskij showed the highest soluble fraction under salinity. The carbohydrate availability and the photosynthetic rate do not seem to be the first limiting factors for plant growth under saline conditions, but the different behavior observed in both genotypes concerning the distribution and use of photoassimilates could help to explain their different salt‐tolerance degrees.
Biphasic effect of copper on the ascorbate‐glutathione pathway in primary leaves of Phaseolus vulgaris seedlings during the early stages of metal assimilation
Authors: Cuypers Ann , Vangronsveld Jaco , Clijsters Herman
Published: January 2004

Copper‐imposed oxidative stress and antioxidative defence responses were investigated in the primary leaves of Phaseolus vulgaris L. plants grown on hydroponics containing 50 μM CuSO4. Copper mainly accumulates in roots; therefore, an increase of the copper content in the leaves was only observed 48 h after the start of the copper supply. Nevertheless, an increase of the thiobarbituric acid reactive metabolites (TBArm) content, an indication of stress, occurred immediately following copper application. Because the ascorbate‐glutathione pathway is considered as a major antioxidative defence mechanism, the evolution of the enzymes and the related metabolites involved in this pathway were studied in the primary leaves as a function of plant copper assimilation. The capacities of monodehydroascorbate reductase (EC 1.6.5.4), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2) were increased before elevated amounts of copper could be detected in the leaves. The early enhancement of glutathione reductase was only temporary. After copper accumulation in the leaves, a second increase of the glutathione reductase capacity and also an increase of the ascorbate peroxidase capacity (EC 1.11.1.11) were observed. These changes in enzymatic capacity modified the level of the metabolites involved. Increase of the ascorbate pool and maintenance in its reduced form was observed immediately after the start of the treatment. In the beginning of the experiment, the glutathione disulphide/reduced glutathione ratio was higher in the treated plants as compared to the controls. However, towards the end of the experiment, the total glutathione pool, as well as the reduced glutathione content, increased, resulting in a lower ratio value for the treated plants. In conlusion, copper‐imposed oxidative stress, as well as the antioxidative defence response in the leaves, appears to be biphasic. An indirect preventive effect on the antioxidative defence system was observed during the first phase before the leaf copper content increased. A root‐to‐shoot signalling system appears to be involved. Direct oxidation by copper of reduced cell metabolites occurred during the second phase when the leaf copper content was enhanced.
Ammonium uptake and cellular alkalisation in roots of Arabidopsis thaliana: The involvement of cytoplasmic calcium1
Authors: Plieth Christoph , Sattelmacher Burkhard , Knight Marc R.
Published: January 2004

Using roots from Arabidopsis thaliana expressing the recombinant calcium indicator aequorin, we show that NH3 uptake and alkalisation of plant cells act as a stimulus which induces transient elevations of the cytoplasmic free calcium concentration ([Ca2+]c). The magnitudes of these [Ca2+]c elevations are dependent on the concentration of the membrane permeable form, NH3, and hence, particularly dependent on the pH in the external medium. EGTA and La3+ are able to significantly suppress the [Ca2+]c transients showing that Ca2+ influx through the plasma membrane is likely to be involved. Verapamil and nifedipine had no inhibitory effects, which suggests that Ca2+ release from internal stores might not contribute significantly to the NH3‐triggered [Ca2+]c response. Pre‐incubation in l‐methionine‐dl‐sulphoximine – an inhibitor of the glutamine synthetase – did not alter the NH3‐induced [Ca2+]c responses at all. These results are consistent with previous studies where NH3‐induced changes of cytoplasmic and vacuolar pH were investigated in maize roots. Furthermore, the similarity between the kinetics of NH3‐driven cellular pH changes demonstrated in previous studies and the [Ca2+]c transients shown here suggests a direct relationship between [Ca2+]c and cellular alkalisation (cytoplasmic pH and/or vacuolar pH). However, the mechanism behind this possible causal relation remains to be elucidated.
Hormonal and developmental regulation of two arabinogalactan‐proteins in xylem of loblolly pine (Pinus taeda)
Authors: No Eun‐Gyu , Loopstra Carol A.
Published: January 2004

The protein cores of two arabinogalactan‐proteins are preferentially expressed at very high levels in differentiating xylem of loblolly pine. Arabinogalactan‐proteins are hypothesized to play important roles in xylem development. The objectives of the described research were to identify signals responsible for the regulation of PtX3H6 and PtX14A9 expression and to assess their expression during seedling development. Application of inhibitors of the phytohormones auxin, gibberellic acid, and ethylene to pine seedlings and subsequent northern blot analyses indicate that PtX3H6 expression is suppressed by inhibitors of auxin and ethylene and that PtX14A9 expression is suppressed by all 3 hormone inhibitors. PtX3H6 is first expressed in germinating embryos. Expression of PtX14A9 is not observed until several days later. In young stems, both genes are expressed more in the radially expanding hypocotyls than in elongating epicotyls with PtX14A9 having a higher ratio of hypocotyl to epicotyl expression. These results indicate that PtX3H6 and PtX14A9 are differently regulated during seedling development and that these differences may be mediated by different hormonal signaling.
Polyamines in marine macroalgae: Levels of putrescine, spermidine and spermine in the thalli and changes in their concentration during glycerol‐induced cell growth in vitro
Authors: Marián Fernando D. , García‐Jiménez Pilar , Robaina Rafael R.
Published: January 2004

The levels of putrescine (Put), spermidine (Spd) and spermine (Spm) were analyzed in naturally collected samples of the marine macroalgae Dyctiota dichotoma, Gelidium canariensis and Grateloupia doryphora. Polyamines (PAs) appeared in free (35–134 μg g−1 fresh weight) and bound TCA‐insoluble form (1 667–2 624 μg g−1 fresh weight). Axenic in vitro cultures of sporelings from G. doryphora were established in the medium containing glycerol. This medium promoted growth and morphogenesis and also increased the free and bound PA levels in the sporelings. Tracer experiments using 70 kBq [U‐14C]‐glycerol showed significant quantities of radioactivity in Put, Spd and Spm after 20 h of incubation. The effects of glycerol on growth were inhibited by the ornithine decarboxylase (EC 4.1.1.17) inhibitor α‐difluoromethylornithine (DFMO). The presence of DFMO in the incubation medium with [U‐14C]‐glycerol also reduced the radioactivity in PAs.
Effects of solidification structure on tear resistance of Al–7% Si–0.4% Mg cast alloys
Authors: HAN S.‐W. , KIM S.‐W. , KUMAI S.
Published: January 2004

The tear resistance behaviour of Al–7% Si–0.4% Mg cast alloys was examined using Kahn‐type tear test specimens. Tests were performed for two permanent mould casts with an ordinary dendrite structure and a semi‐liquid die cast with a globular cell and fine grain structure. The microstructure of the two permanent mould casts was controlled by the cooling rates and the addition of Ti elements. Tear resistance was evaluated by the ‘pop‐in’ stress, the energies required for crack initiation, UEi and the crack propagation, UEp. Special attention was paid to an effective microstructural parameter for tear resistance improvement. Pop‐in, indicating sudden crack extension and arrest, was observed in all specimens. Homogeneous deformation occurs near the notch tip of the semi‐liquid die cast, characterized by a refined grain structure. Refinement of the grain size is more effective than that of the dendrite cell size or eutectic Si particle size to increase the energy for crack initiation. Unit propagation energy, UEp, can be converted into a critical stress intensity factor, Kc, which in the semi‐liquid die cast was improved due to an increased amount of slant or shear fracture surface.
Fatigue crack propagation in cast duplex stainless steels: thermal ageing and microstructural effects
Authors: CALONNE V. , GOURGUES A. F. , PINEAU A.
Published: January 2004

The ferrite phase of cast duplex stainless steels becomes embrittled after thermal ageing, leading to a significant decrease in fracture properties. In the present paper, the influence of ageing and solidification structure on the fatigue crack growth rates (FCGRs) and on the fatigue crack growth mechanisms in a cast duplex stainless steel is studied. FCGRs measured at room temperature increase slightly after ageing at 400 °C, due to ferrite cleavage and to the resulting irregular shape of the crack front. The crack propagates without any preferential path by successive ruptures of ferrite and austenite phases. The macroscopic crack propagation plane depends on the crystallographic orientation of the ferrite grain. Secondary cracks can appear due to the complex solidification structure. This in turn influences the FCGR. The fatigue crack closure level decreases with increasing ageing. This can be explained by a decrease in the kinematic cyclic hardening of these materials.
Near‐tip microcrack shielding in advanced ceramics
Authors: CHEN C. K.
Published: January 2004

Recent manufacturing of advanced ceramics has developed phase transformation and cracks tilted or bridged to enhance ceramic‐inherent toughness. However, main crack and near‐tip microcracks interaction is another prominent means in toughening of the ceramic materials. In this study, mechanics of discrete model combined with alternative iterating numerical technique is developed and applied in assessment of main–microcrack interaction. Consequences of main–microcrack interaction can either shield or amplify the resulting main crack stress intensity factor, which accounts for the increase or decrease of ceramic toughness. Numerical outcomes show good agreement with the available solutions in the literatures; in addition results also reveal that the toughness shielding or amplification is dependent on the type of loadings as well as location/orientation of the microcrack. Nevertheless, residual normal stress plays an important role in shielding/amplification region trade‐off. This work may provide a useful quantitative tool in ceramic design and a valuable insight into main–micro interaction phenomenon.
Simulating small crack growth behaviour using crystal plasticity theory and finite element analysis
Authors: POTIRNICHE G. P. , DANIEWICZ S. R. , NEWMAN J. C.
Published: January 2004

Predictions of small crack growth under cyclic loading in aluminium alloy 7075 are performed using finite element analysis (FEA), and results are compared with published experimental data. A double‐slip crystal plasticity model is implemented within the analyses to enable the anisotropic nature of individual grains to be approximated. Small edge‐cracks in a single grain with a starting length of 6 μm are incrementally grown following a node‐release scheme. Crack‐tip opening displacements (CTOD) and crack opening stresses are calculated during the simulated crack growth, and da/dN against ΔK diagrams are computed. Interactions between the crack tip and a grain boundary are also considered. The computations are shown to accurately capture the magnitude and the variability normally observed in small crack fatigue data.
The political economy of international trade and factor mobility
Authors: Facchini Giovanni
Published: January 2004

Abstract. Free trade in goods and factors is efficient. When we move away from economic theory and consider the policies actually followed by governments, we observe distortions being implemented both on goods and factors trades. It is natural then to question the relative merits of the two types of intervention, and the normative literature has provided only partial answers. We ask then why is the international flow of goods and factors not free, and the political economy literature has looked at the two issues only separately. In studying the determination of trade policy, a theoretical paradigm has emerged, focusing on the role of influence driven contributions. This approach has also found strong empirical support. The literature on the political economy of factor mobility, on the other hand, is fragmented. Distortions in labor and capital flows are typically the subject of different studies, and only recently a unified framework has been proposed. More work has to be done in this area as well as in integrating the political economy of trade and factor movements.
International Convergence of Accounting Practices: Choosing between IAS and US GAAP
Authors: Tarca Ann
Published: January 2004

This study examines reporting practices of a sample of foreign listed and domestic‐only listed companies from the United Kingdom, France, Germany, Japan and Australia to determine the extent to which companies voluntarily use “international” standards. Two types of use of non‐national standards in the consolidated accounts presented to the public are considered: adoption of “international” standards instead of national standards, and supplementary use where “international” standards are used in conjunction with national standards. “International” standards are defined as US GAAP or IAS (now IFRS). The study tests for a preference for either set of standards and considers the relationship of choice of regime with firm attributes.

The results show significant voluntary use of “international” standards in all five countries and among foreign listed and domestic‐only listed companies. Companies using “international” standards are likely to be larger, have more foreign revenue and to be listed on one or more foreign stock exchanges. US GAAP is the predominant choice, but IAS are used by many firms in Germany and some in Japan. Firms listed in the United States' regulated markets (NYSE and NASDAQ) are more likely to choose US GAAP, but companies traded in the OTC market often select IAS.

The study demonstrates for managers and regulators that there is considerable support for “international” standards, and that choice of IAS or US GAAP relates to specific firm characteristics which differ according to a firm's country of origin. Most use of “international” standards reflects individual countries' institutional frameworks, confirming the key role of national regulators and standard setters in assisting companies to achieve more comparable international reporting.
Collective Goods, Common Agency, and Third‐Party Intervention
Authors: Siqueira Kevin , Sandler Todd
Published: January 2004

Voluntary contributions to multiple public goods may involve many contributors (principals) who condition their payments to a single provider (agent) based on realized provision. If the agent's efforts on these goods are unobservable, then a common agency problem results with a third‐best outcome owing to agency costs, free riding, and competitive interests. The latter manifests itself in the principals punishing the agent for providing an alternative public good (for which they have no interest) to a different set of principals. Remedies may require multiple policy instruments unlike the standard prescription for the public good or common agency problem in isolation. Moreover, the sequence of actions is essential for addressing the combined problems.
Comparing the True Cost of Living Indices of Demographically Different Households
Authors: Lyssiotou Panayiota , Pashardes Panos
Published: January 2004

The comparison of true cost of living indices between demographically different households (relative equivalence scale) is argued to be sensitive to the way demographic characteristics enter demand analysis. In particular, parameters reflecting the cost of demographic characteristics at base prices, though themselves do not have welfare (equivalence scale) interpretation, can alter the benchmark from which demographically varying inflation effects are measured. The empirical analysis, based on a rank‐3 demand system applied to UK individual household data, shows that the inflation adjustment of child benefits can vary with the way demographic costs at base period prices are specified.
Neuro‐Fuzzy Control of Railcar Vibrations Using Semiactive Dampers
Authors: Atray Vipul S. , Roschke Paul N.
Published: January 2004

Abstract:  This article describes a new approach to reducing vertical vibrations in a 70‐ton railcar using a neuro‐fuzzy controller and a magnetorheological (MR) damper. A semiactive control technique is developed for a two‐degree‐of‐freedom quarter car model of the railcar that has an installed MR damper. A fuzzy controller in real time continuously updates damping properties of the device. The controller uses feedback acceleration of the freight mass to specify a voltage signal to the MR damper. Correlations between acceleration (controller input) and voltage applied to the MR damper (controller output) are developed using Neuro Fuzzy Controller (NEFCON). To assess effectiveness of the semiactive control scheme, responses of the railcar to various haul conditions are compared with those for uncontrolled and for passive operating conditions of the MR damper. Results indicate that semiactively controlled MR dampers can reduce vibrations to acceptable levels provided that sufficient force capacity can be supplied by the damper.
Position‐Invariant Neural Network for Digital Pavement Crack Analysis
Authors: Lee Byoung Jik , Lee Hosin “David”
Published: January 2004

Abstract:  This article presents an integrated neural network‐based crack imaging system to classify crack types of digital pavement images. This system includes three neural networks: (1) image‐based neural network, (2) histogram‐based neural network, and (3) proximity‐based neural network. These three neural networks were developed to classify various crack types based on the subimages (crack tiles) rather than crack pixels in digital pavement images. These spatial neural networks were trained using artificially generated data following the Federal Highway Administration (FHWA) guidelines. The optimal architecture of each neural network was determined based on the testing results from different sets of the number of hidden units, learning coefficients, and the number of training epochs. To validate the system, actual pavement pictures taken from pavements as well as the computer‐generated data were used. The proximity value is determined by computing relative distribution of crack tiles within the image. The proximity‐based neural network effectively searches the patterns of various crack types in both horizontal and vertical directions while maintaining its position invariance. The final result indicates that the proximity‐based neural network produced the best result with the accuracy of 95.2% despite its simplest neural network structure with the least computing requirement.