bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of mechanical boundary conditions on the electrocaloric properties of ferroelectric thin films
Authors: Akcay G. , Alpay S. P. , Rossetti G. A. , Scott J. F.
Published: January 2008

A thermodynamic analysis of the electrocaloric (EC) effect in BaTiO3 ferroelectric thin films has been carried out under differing mechanical boundary conditions. It is shown that both the magnitude of the electrocaloric effect and temperature at which it is maximized depend not only on the extent of the applied field change but also on the value of the initial field. For initial fields smaller than a critical value the EC effect is largest at the phase transition temperature but the effect is a strong function of temperature. For external electrical fields larger than this value, conversely, the EC effect is the largest at a higher temperature and is a weak function of temperature. Perfect lateral clamping transforms the first-order phase transition into a second-order transition, lowering the magnitude of the electrocaloric effect and dependence on temperature. Compressive and tensile misfit strains also alter the nature of the phase transition and affect the electrocaloric properties in an analogous way. A compressive misfit strain shifts the maximum in the EC effect to higher temperatures, reduces its magnitude, and reduces its dependence on temperature, while tensile misfit strain results in the opposite effects. Control of the misfit strain by appropriate choice of substrate provides potential means to vary both the magnitude and the temperature sensitivity of the EC effect for use in cooling or thermodielectric power conversion devices.
Electron spin resonance study of Bi(1−x)CaxMnO3
Authors: Kurian Joji , Singh R.
Published: January 2008

The temperature dependent electron spin resonance (ESR) studies on Bi(1−x)CaxMnO3 (x=0.4, 0.45, and 0.5) having a triclinic structure were carried out to understand the spin dynamics, short-range magnetic interactions, and micromagnetic phase formation in these materials. The phase transition into charge-ordered (CO) state takes place at temperatures TCO=313K (for x=0.4 and 0.5) and at 317K (for x=0.45) samples. The data are explained in view of the existence of mixed valence clusters of Mn3+–Mn4+ ions coupled by strong short-range ferromagnetic (FM) double-exchange interactions in the paramagnetic state. The orbital ordering changes from FM to antiferromagnetic (AFM) type ∼190K (for x=0.4 and 0.5) and ∼180K (for x=0.45). The Néel Temperatures TN are 163K (for x=0.4 and 0.5) and 153K (for x=0.45). The temperature independence of ln (DI) double integrated intensity of the ESR resonance below 125K is ascribed to the existence of FM ordered microinhomogeneities embedded in the AFM ordered bulk sample. The TCO and TN values are found to be weakly dependent on the composition. The temperature dependence of ESR linewidth near TN has been analyzed in view of the spin-spin relaxation near magnetic critical points, as given by Seehra and Huber [AIP Conf. Proc. 24, 261 (1975)].
Novel pinning phenomena in Nb thin films with square pinning arrays
Authors: Horng Lance , Yang T. J. , Cao R. , Wu T. C. , Lin J. C. , Wu J. C.
Published: January 2008

Electron-beam lithography and reaction dry etching techniques have been used to fabricate superconductor thin films with regular square hole arrays to explore the vortex pinning behavior. Magnetotransport measurements were carried out by a four-probe technique. Periodic critical current matching peaks are observed. We found that the height of the third matching peak is close to that of the fourth matching peak for film with holes of diameter of 200nm at certain temperatures, and it appears that the third matching peak is missing. Similar peculiar phenomena are observed for films with holes of different diameters, but the missing peaks are at the fourth or fifth matching field for larger holes. We made molecular dynamic simulations to study the ground state vortex distributions and the dynamics of the vortex motion. The simulation results offer good explanations to the features we found in the experiments.
Magnetic and magnetostrictive properties and anisotropy compensation in Tb0.1Ho0.9−xPrx(Fe0.9B0.1)2 (⩽x⩽0.4) compounds
Authors: Ren W. J. , Li D. , Liu W. , Li J. , Zhang Z. D.
Published: January 2008

Tb 0.1 Ho 0.9 − x Pr x Fe 2 and Tb0.1Ho0.9−xPrx(Fe0.9B0.1)2 (0⩽x⩽0.4) alloys were prepared by arc melting and subsequent annealing. It was found that the addition of boron is helpful for the formation of MgCu2-type Laves phase. The spin reorientation temperature of Tb0.1Ho0.9−xPrx(Fe0.9B0.1)2 compounds decreases and the easy magnetization direction rotates from ⟨100⟩ to ⟨111⟩ when x is increased from 0 to 0.4, demonstrating the anisotropy compensation between Ho3+ and Pr3+ ions. The anisotropic magnetostriction λa=λ∥-λ⊥ at room temperature increases with increasing Pr content when x⩽0.2, which is ascribed to the much larger magnetostriction of PrFe2 than of HoFe2 and the decrease of the anisotropy due to compensation. The Tb0.1Ho0.7Pr0.2(B0.1)2 compound close to the anisotropy compensation point has the largest magnetostriction at room temperature.
Kinetics of reactive ion etching upon single-walled carbon nanotubes
Authors: Kato Toshiaki , Hatakeyama Rikizo
Published: January 2008

The remarkable etching reaction of single-walled carbon nanotubes (SWNTs) has been observed in their growth of the parameter-controlled plasma chemical vapor deposition (CVD). The time evolution study of the SWNTs growth leads to establishing a growth equation which can completely express the growth kinetics of SWNTs in the plasma CVD. The growth equation is found to reveal that there are several key parameters which directly affect the etching reaction of SWNTs. Furthermore, such kinetics of the SWNT etching in plasmas can perfectly be explained with a reactive ion etching model.
Overexpression of the vacuolar metal/proton exchanger AtMHX in tomato causes decreased cell expansion and modifications in the mineral content
Authors: Berezin Irina , Brook Emil , Mizrahi Keren , Mizrachy-Dagry Talya , Elazar Meirav , Zhou Suping , Shaul Orit
Published: January 2008

AtMHX is an Arabidopsis vacuolar transporter that exchanges protons with Mg2+, Zn2+ and Fe2+ ions. Tobacco (Nicotiana tabacum (L.)) plants that overexpressed AtMHX showed necrotic lesions, similar to those shown by plants having increased proton influx from the apoplast into the cytosol. This raised the assumption that AtMHX affects the proton homeostasis of cells. Here, we expressed AtMHX in tomato (Lycopersicon esculentum Mill.). The results clarified that the common response of all plant species in which AtMHX was overexpressed thus far was a reduction in plant mass. Transformed tomato plants, in which this reduction was greater compared with tobacco or Arabidopsis thaliana (L.), exhibited reduced cell expansion and a reduction in potassium content. Modifications were also seen in the content of other minerals, including not only metals that can be carried by AtMHX. These changes may thus reflect not only direct metal transport by AtMHX but also the consequences of reduction in cell size. Decreased cell expansion characterises plants with diminished expression of vacuolar proton pumps, presumably due to reduction in the proton-motive force (PMF) necessary to drive solute (mainly potassium) influx into vacuoles and consequently water uptake. This supported a model in which AtMHX-mediated proton efflux from vacuoles affects the PMF, potassium influx, and cell expansion.
Modelling and comparison of growth of the silver-lip pearl oyster Pinctada maxima (Jameson) (Mollusca : Pteriidae) cultured in West Papua, Indonesia
Authors: Lee Anne M. , Williams Ashley J. , Southgate Paul C.
Published: January 2008

A commonly used approach to quantifying growth is to fit mathematical models to length-at-age data. Growth of the silver-lip pearl oysters, Pinctada maxima, cultured at a commercial pearl farm in West Papua, Indonesia was expressed mathematically by fitting five growth models (Gompertz, Richards, Logistic, Special von Bertalanffy Growth Function (VBGF) and General VBGF) to length-at-age data. The criteria used to determine the best fit model were a low mean residual sum of squares (MRSS), high coefficient of determination (r2) and low deviation of the asymptotic length (L∞) from the maximum length (Lmax). Using these criteria, the models were ranked accordingly: Special VBGF; General VBGF; Gompertz; Richards and Logistic models. The Special VBGF yielded the best fit (L∞ = 168.38 mm; K = 0.930 year–1; t0 = 0.126; MRSS = 208.64; r2 = 0.802; Deviation of L∞ from Lmax = 37.52 mm) and, accordingly, was used to model the growth of oysters cultured at three sites and two depths within the farm. Likelihood ratio tests were used to compare growth of oysters cultured at these sites and depths. Based on L∞ and K values, favourable sites and depths could be determined that optimised growth requirements for the various stages of P. maxima culture. Sites with high K and L∞ values were preferred sites for culturing juvenile oysters before pearl production, when high growth rate is essential to produce large numbers of oysters in the shortest time possible. In addition, high L∞ may facilitate implantation of larger nuclei conducive to the production of larger, more valuable pearls. Conversely, sites with low K values were preferred sites for weakening P. maxima before pearl ‘seeding’, a process undertaken to minimise nucleus rejection after seeding.
Cytoplasmic Pink1 activity protects neurons from dopaminergic neurotoxin MPTP
Authors: Haque M. Emdadul , Thomas Kelly J. , D'Souza Cheryl , Callaghan Steve , Kitada Tohru , Slack Ruth S. , Fraser Paul , Cookson Mark R. , Tandon Anurag , Park David S.
Published: January 2008

PTEN-induced putative kinase 1 (Pink1) is a recently identified gene linked to a recessive form of familial Parkinson's disease (PD). The kinase contains a mitochondrial localization sequence and is reported to reside, at least in part, in mitochondria. However, neither the manner by which the loss of Pink1 contributes to dopamine neuron loss nor its impact on mitochondrial function and relevance to death is clear. Here, we report that depletion of Pink1 by RNAi increased neuronal toxicity induced by MPP
+
. Moreover, wild-type Pink1, but not the G309D mutant linked to familial PD or an engineered kinase-dead mutant K219M, protects neurons against MPTP both
in vitro
and
in vivo
. Intriguingly, a mutant that contains a deletion of the putative mitochondrial-targeting motif was targeted to the cytoplasm but still provided protection against 1-methyl-4-phenylpyridine (MPP
+
)/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced toxicity. In addition, we also show that endogenous Pink1 is localized to cytosolic as well as mitochondrial fractions. Thus, our findings indicate that Pink1 plays a functional role in the survival of neurons and that cytoplasmic targets, in addition to its other actions in the mitochondria, may be important for this protective effect.
Probabilistic assembly of human protein interaction networks from label-free quantitative proteomics
Authors: Sardiu Mihaela E. , Cai Yong , Jin Jingji , Swanson Selene K. , Conaway Ronald C. , Conaway Joan W. , Florens Laurence , Washburn Michael P.
Published: January 2008

Large-scale affinity purification and mass spectrometry studies have played important roles in the assembly and analysis of comprehensive protein interaction networks for lower eukaryotes. However, the development of such networks for human proteins has been slowed by the high cost and significant technical challenges associated with systematic studies of protein interactions. To address this challenge, we have developed a method for building local and focused networks. This approach couples vector algebra and statistical methods with normalized spectral counting (NSAF) derived from the analysis of affinity purifications via chromatography-based proteomics. After mathematical removal of contaminant proteins, the core components of multiprotein complexes are determined by singular value decomposition analysis and clustering. The probability of interactions within and between complexes is computed solely based upon NSAFs using Bayes' approach. To demonstrate the application of this method to small-scale datasets, we analyzed an expanded human TIP49a and TIP49b dataset. This dataset contained proteins affinity-purified with 27 different epitope-tagged components of the chromatin remodeling SRCAP, hINO80, and TRRAP/TIP60 complexes, and the nutrient sensing complex Uri/Prefoldin. Within a core network of 65 unique proteins, we captured all known components of these complexes and novel protein associations, especially in the Uri/Prefoldin complex. Finally, we constructed a probabilistic human interaction network composed of 557 protein pairs.
Genome-wide B1 retrotransposon binds the transcription factors dioxin receptor and Slug and regulates gene expression
in vivo
Authors: Roman Angel Carlos , Benitez Dixan A. , Carvajal-Gonzalez Jose M. , Fernandez-Salguero Pedro M.
Published: January 2008

Alterations in tissue-specific gene expression greatly affect cell function. Transcription factors (TFs) interact with
cis
-acting binding sites in noncoding enhancer promoter regions. Transposable elements (TEs) are abundant and similarly represented among mammalian genomes. TEs are important in gene regulation, but their function is not well understood. We have characterized a TE containing functional TF-binding sites for the carcinogen-activated dioxin receptor xenobiotic responsive element (XRE) and the epithelial–mesenchymal transition regulator Slug (Slug site). A
Mus
promoter database was scanned for XREs to predict coregulation with other TFs. We identified an overrepresented (1,398 genes) B1 retrotransposon containing XRE and Slug sites within 35 bp of each other (designated as B1-X35S). This B1-X35S retrotransposon differed from classic B1s by the presence of the Slug site and by its differential nucleotide conservation outside the X35S region. Phylogenetically, B1-X35S appeared recently in evolution, close to the B1-B subfamily. Comparative gene expression in 61 mouse tissues revealed that B1-X35S-containing genes had lower median expression levels than those with canonical B1 TEs, suggesting a repressive role for X35S. Indeed, X35S was functional and able to bind aryl hydrocarbon (dioxin) receptor (AhR) and Slug and, importantly, to repress
cis
-reporter genes. Moreover, AhR and Slug were recruited to X35S
in vivo
and repressed the endogenous expression of X35S-containing genes. Our results demonstrate the existence of a widely present B1 subfamily in the mouse. Because AhR and Slug are relevant in tumor development and differentiation, X35S may represent a genome-wide regulatory mechanism and a tool to modulate gene expression.
Anoikis effector Bit1 negatively regulates Erk activity
Authors: Kairouz-Wahbe Rania , Biliran Hector , Luo Xiuquan , Khor IngWei , Wankell Miriam , Besch-Williford Cynthia , Pascual Jaime , Oshima Robert , Ruoslahti Erkki
Published: January 2008

Bcl-2 inhibitor of transcription (Bit1) is a mitochondrial protein that functions as a peptidyl-tRNA hydrolase, but, when released into the cytoplasm, it elicits apoptosis. The proapoptotic function is uniquely counteracted by integrin-mediated cell attachment. We generated a conditional KO mouse of the Bit1 gene by using the Cre-LoxP recombination system. Bit1-null mice were born alive but with some developmental abnormalities. They developed a runting syndrome after birth and died within the first 2 weeks. Cultured fibroblasts from the Bit1-null embryos [mouse embryo fibroblasts (MEFs)] were more resistant to cell death induced by loss of attachment to extracellular matrix (anoikis) than cells from the wild-type or heterozygous littermates. MEFs and tissues from Bit1 KO mice displayed a marked increase in Erk phosphorylation. Knocking down Bit1 expression in cultured cells resulted in increased Erk activation, and partially knocking down Erk reversed the increased anoikis resistance of Bit1 knockdown. The enhanced Erk activation was associated with decreased Erk phosphatase activity. These studies establish the physiological significance of Bit1 activity and begin to delineate a Bit1 signaling pathway that acts through Erk regulation.
Distributed Detection in Wireless Sensor Networks Using Dynamic Sensor Thresholds
Authors: Ray Priyadip , Varshney Pramod K.
Published: January 2008

This paper presents a new approach for distributed target detection in wireless sensor networks (WSNs). Contrary to the conventional practice where every sensor uses an identical threshold for decision-making, an unequal and dynamic local sensor threshold selection scheme is proposed. This threshold selection scheme is based on a recently proposed statistical metric for multiple testing problems called the False Discovery Rate (FDR). Assuming a signal attenuation model, where the received signal power decays as the distance from the target increases, various performance indices like the system level probability of detection and the probability of false alarm are studied. Simulation results are provided to demonstrate the effectiveness of this approach.
Social Marketing Analysis of 2 Years of Hand Hygiene Promotion
Authors: Mah Manuel W. , Tam Yat Cho , Deshpande Sameer
Published: January 2008

Objective.

To assess published hand hygiene behavioral interventions that employed a social marketing framework and to recommend improvements to future interventions.

Methods.

We performed a systematic literature review by searching the PubMed database and the Cumulative Index to Nursing and Allied Health Literature for published articles about hand hygiene behavioral interventions in healthcare facilities, schools, and community settings. Our analysis included articles that describe multifaceted interventions and evaluated them with predefined social marketing benchmark criteria.

Results.

Of 53 interventions analyzed in this review, 16 (30.2%) employed primary formative audience research, 5 (9.4%) incorporated social or behavioral theories, 27 (50.9%) employed segmentation and targeting of the audience, 44 (83.0%) used components of the “marketing mix,” 3 (5.7%) considered the influence of competing behaviors, 7 (13.2%) cultivated relationships with the target audience, and 15 (28.3%) provided simple behavioral messages. Thirty-five (66.0%) of the interventions demonstrated a significant improvement in performance, but only 21 (39.6%) were considered to have a strong evaluative design. The median duration of the interventions was 8.0 months.

Conclusions.

From a social marketing perspective, the promotion of hand hygiene could be improved in several ways. The effectiveness of social marketing in hand hygiene promotion should be tested in future interventions.
Seasonal appearance of expatriated boreal copepods in the Oyashio–Kuroshio mixed region
Authors: Kobari Toru , Moku Masatoshi , Takahashi Kazutaka
Published: January 2008

Kobari, T., Moku, M., and Takahashi, K. 2008. Seasonal appearance of expatriated boreal copepods in the Oyashio–Kuroshio mixed region. – ICES Journal of Marine Science, 65: 469–476. Seasonal changes in abundance, biomass, and community structure of ontogenetically migrating copepods were investigated using monthly zooplankton samples from the Oyashio–Kuroshio mixed region (OKMR) to evaluate impacts of the copepod community expatriated from more northerly waters on carbon flow in southern areas. The copepod community comprised more than half the total zooplankton biomass and exhibited seasonal fluctuations, although they were minor components in terms of abundance. The ontogenetic migrants increased their abundance and biomass during May–July when Oyashio waters dominated at the surface. They were almost absent from 0 to 150 m during August to December. Predominant species were Eucalanus bungii and Metridia pacifica for abundance and Neocalanus cristatus for biomass. Seasonal changes in their abundance and stage composition indicated that surface development, dormancy, and reproduction were comparable in schedule with those reported in the Oyashio region. We suggest that the ontogenetically migrating copepods appearing in this area are populations transported with a southward Oyashio intrusion during surface development seasons, then by both downward migration and advection of dormant populations in the submerging Oyashio flow. We discuss impacts of the expatriated copepods on food availability for mesopelagic fish in the OKMR.
Maxwell and the science of colour
Authors: Longair Malcolm S
Published: January 2008

This non-technical review of Maxwell's contributions to the quantitative theory of colour was presented at a symposium in Aberdeen to celebrate the 150th anniversary of his appointment as professor of natural philosophy at Marischal College. Maxwell maintained his interest in the science of light and colour from his childhood to the last decade of his life. He lavished the same care and imagination on these studies as he did on his epochal contributions to electromagnetism and statistical physics.
Maxwell's electromagnetic theory and special relativity
Authors: Hall Graham
Published: January 2008

This paper presents a brief history of electromagnetic theory from ancient times up to the work of Maxwell and the advent of Einstein's special theory of relativity. It is divided into five convenient periods and the intention is to describe these developments for the benefit of a lay scientific audience and with the minimum of technical detail.
The genome of Pelotomaculum thermopropionicum reveals niche-associated evolution in anaerobic microbiota
Authors: Kosaka Tomoyuki , Kato Souichiro , Shimoyama Takefumi , Ishii Shunichi , Abe Takashi , Watanabe Kazuya
Published: January 2008

The anaerobic biodegradation of organic matter is accomplished by sequential syntrophic catabolism by microbes in different niches. Pelotomaculum thermopropionicum is a representative syntrophic bacterium that catalyzes the intermediate bottleneck step in the anaerobic-biodegradation process, whereby volatile fatty acids (VFAs) and alcohols produced by upstream fermenting bacteria are converted to acetate, hydrogen, and carbon dioxide (substrates for downstream methanogenic archaea). To reveal genomic features that contribute to our understanding of the ecological niche and evolution of P. thermopropionicum, we sequenced its 3,025,375-bp genome and performed comparative analyses with genomes of other community members available in the databases. In the genome, 2920 coding sequences (CDSs) were identified. These CDSs showed a distinct distribution pattern in the functional categories of the Clusters of Orthologous Groups database, which is considered to reflect the niche of this organism. P. thermopropionicum has simple catabolic pathways, in which the propionate-oxidizing methylmalonyl–CoA pathway constitutes the backbone and is linked to several peripheral pathways. Genes for most of the important catabolic enzymes are physically linked to those for PAS-domain-containing regulators, suggesting that the catabolic pathways are regulated in response to environmental conditions and/or global cellular situations rather than specific substrates. Comparative analyses of codon usages revealed close evolutionary relationships between P. thermopropionicum and other niche members, while it was distant from phylogenetically related sugar-fermenting bacteria. These analyses suggest that P. thermopropionicum has evolved as a syntrophy specialist by interacting with niche-associated microbes.
Characterization of the Monoterpene Synthase Gene tps26, the Ortholog of a Gene Induced by Insect Herbivory in Maize
Authors: Lin Changfa , Shen Binzhang , Xu Zhennan , Köllner Tobias G. , Degenhardt Jörg , Dooner Hugo K.
Published: January 2008

Plants damaged by insects can synthesize and release volatile chemicals that attract natural enemies of the herbivore. The maize (Zea mays subsp. mays) terpene synthase gene stc1 is part of that indirect defense response, being induced in seedling blades in response to herbivory by beet army worm. Many genes in maize are duplicated because of a past whole-genome duplication event, and several of these orthologs display different expression patterns. We report here the isolation and characterization of tps26 and confirm by homology and synteny criteria that it is the ortholog of stc1. Prior genetic analysis revealed that the stc1 function is not duplicated, raising the interesting question of how the two orthologs have become differentiated in their expression. tps26 encodes a 633-amino acid protein that is highly conserved with STC1. Like stc1, tps26 is induced by wounding, but in the roots and leaf sheath, instead of the blade, and not in response to beet army worm feeding. tps26 maps near a quantitative trait locus for Southwestern corn borer resistance, making it a plausible candidate gene for that quantitative trait locus. However, while possessing highly polymorphic tps26 alleles, the resistant and susceptible parents of the mapping population do not differ in levels of tps26 expression. Moreover, tps26 is not induced specifically by Southwestern corn borer feeding. Therefore, although they share a wounding response, the stc1 and tps26 maize orthologs differ in their tissue specificity and their induction by insect herbivores. The N termini of STC1 and TPS26 are predicted to encode plastid transit peptides; fusion proteins of green fluorescent protein to either N terminus localized to the plastid, confirming that prediction. The mature proteins, but not the respective complete proteins, were active and synthesized a blend of monoterpenes, indicating that they are monoterpene synthases. A gene closely related to stc1/tps26 is found in the sorghum (Sorghum spp.) genome at a location that is not orthologous with stc1. The possible origin of stc1-like genes is discussed.
The Structure of Chloroplast DNA Molecules and the Effects of Light on the Amount of Chloroplast DNA during Development in Medicago truncatula
Authors: Shaver Jeffrey M. , Oldenburg Delene J. , Bendich Arnold J.
Published: January 2008

We used pulsed-field gel electrophoresis and restriction fragment mapping to analyze the structure of Medicago truncatula chloroplast DNA (cpDNA). We find most cpDNA in genome-sized linear molecules, head-to-tail genomic concatemers, and complex branched forms with ends at defined sites rather than at random sites as expected from broken circles. Our data suggest that cpDNA replication is initiated predominantly on linear DNA molecules with one of five possible ends serving as putative origins of replication. We also used 4′,6-diamidino-2-phenylindole staining of isolated plastids to determine the DNA content per plastid for seedlings grown in the dark for 3 d and then transferred to light before being returned to the dark. The cpDNA content in cotyledons increased after 3 h of light, decreased with 9 h of light, and decreased sharply with 24 h of light. In addition, we used real-time quantitative polymerase chain reaction to determine cpDNA levels of cotyledons in dark- and light-grown (low white, high white, blue, and red light) seedlings, as well as in cotyledons and leaves from plants grown in a greenhouse. In white, blue, and red light, cpDNA increased initially and then declined, but cpDNA declined further in white and blue light while remaining constant in red light. The initial decline in cpDNA occurred more rapidly with increased white light intensity, but the final DNA level was similar to that in less intense light. The patterns of increase and then decrease in cpDNA level during development were similar for cotyledons and leaves. We conclude that the absence in M. truncatula of the prominent inverted repeat cpDNA sequence found in most plant species does not lead to unusual properties with respect to the structure of plastid DNA molecules, cpDNA replication, or the loss of cpDNA during light-stimulated chloroplast development.
Complex Signaling Network in Regulation of Adenosine 5′-Phosphosulfate Reductase by Salt Stress in Arabidopsis Roots
Authors: Koprivova Anna , North Kathryn Anne , Kopriva Stanislav
Published: January 2008

Sulfur-containing compounds play an important role in plant stress defense; however, only a little is known about the molecular mechanisms of regulation of sulfate assimilation by stress. Using known Arabidopsis (Arabidopsis thaliana) mutants in signaling pathways, we analyzed regulation of the key enzyme of sulfate assimilation, adenosine 5′-phosphosulfate reductase (APR), by salt stress. APR activity and mRNA levels of all three APR isoforms increased 3-fold in roots after 5 h of treatment with 150 mm NaCl. The regulation of APR was not affected in mutants deficient in abscisic acid (ABA) synthesis and treatment of the plants with ABA did not affect the mRNA levels of APR isoforms, showing that APR is regulated by salt stress in an ABA-independent manner. In mutants deficient in jasmonate, salicylate, or ethylene signaling, APR mRNA levels were increased upon salt exposure similar to wild-type plants. Surprisingly, however, APR enzyme activity was not affected by salt in these plants. The same result was obtained in mutants affected in cytokinin and auxin signaling. Signaling via gibberellic acid, on the other hand, turned out to be essential for the increase in APR mRNA by salt treatment. These results demonstrate an extensive posttranscriptional regulation of plant APR and reveal that the sulfate assimilation pathway is controlled by a complex network of multiple signals on different regulatory levels.
A Plasma Membrane-Anchored Fluorescent Protein Fusion Illuminates Sieve Element Plasma Membranes in Arabidopsis and Tobacco
Authors: Thompson Matthew V. , Wolniak Stephen M.
Published: January 2008

Rapid acquisition of quantitative anatomical data from the sieve tubes of angiosperm phloem has been confounded by their small size, their distance from organ surfaces, and the time-consuming nature of traditional methods, such as transmission electron microscopy. To improve access to these cells, for which good anatomical data are critical, a monomeric yellow fluorescent protein (mCitrine) was N-terminally fused to a small (approximately 6 kD) membrane protein (AtRCI2A) and stably expressed in Arabidopsis thaliana (Columbia-0 ecotype) and Nicotiana tabacum (‘Samsun’) under the control of a companion cell-specific promoter (AtSUC2p). The construct, called by its abbreviation SUmCR, yielded stable sieve element (SE) plasma membrane fluorescence labeling, even after plastic (methacrylate) embedding. In conjunction with wide-field fluorescence measurements of sieve pore number and position using aniline blue-stained callose, mCitrine-labeled material was used to calculate rough estimates of sieve tube-specific conductivity for both species. The SUmCR construct also revealed a hitherto unknown expression domain of the AtSUC2 Suc-H+ symporter in the epidermis of the cell division zone of developing root tips. The success of this construct in targeting plasma membrane-anchored fluorescent proteins to SEs could be attributable to the small size of AtRCI2A or to the presence of other signals innate to AtRCI2A that permit the protein to be trafficked to SEs. The construct provides a hitherto unique entrée into companion cell-to-SE protein targeting, as well as a new tool for studying whole-plant phloem anatomy and architecture.
Serine Palmitoyltransferase, a Key Enzyme for de Novo Synthesis of Sphingolipids, Is Essential for Male Gametophyte Development in Arabidopsis
Authors: Teng Chong , Dong Haili , Shi Lihua , Deng Yan , Mu Jinye , Zhang Jian , Yang Xiaohui , Zuo Jianru
Published: January 2008

Sphingolipids are important signaling molecules involved in various cellular activities. De novo sphingolipid synthesis is initiated by a rate-limiting enzyme, serine palmitoyltransferase (SPT), a heterodimer consisting of LONG-CHAIN BASE1 (LCB1) and LCB2 subunits. A mutation in the Arabidopsis thaliana LCB1 gene, lcb1-1, was found to cause embryo lethality. However, the underpinning molecular and cellular mechanisms remain largely unclear. Here, we report the identification of the fumonisin B1 resistant11-2 (fbr11-2) mutant, an allele of lcb1-1. The fbr11-2 mutation, most likely an allele stronger than lcb1-1, was transmitted only through female gametophytes and caused the formation of abortive microspores. During the second pollen mitosis, fbr11-2 initiated apoptotic cell death in binucleated microspores characteristic of nuclear DNA fragmentation, followed by cytoplasm shrinkage and organelle degeneration at the trinucleated stage. In addition, a double mutant with T-DNA insertions in two homologous LCB2 genes showed a phenotype similar to fbr11-2. Consistent with these observations, the FBR11/LCB1 expression was confined in microspores during microgametogenesis. These results suggest that SPT-modulated programmed cell death plays an important role in the regulation of male gametophyte development.
MYB72 Is Required in Early Signaling Steps of Rhizobacteria-Induced Systemic Resistance in Arabidopsis
Authors: Van der Ent Sjoerd , Verhagen Bas W.M. , Van Doorn Ronald , Bakker Daniel , Verlaan Maarten G. , Pel Michiel J.C. , Joosten Ruth G. , Proveniers Marcel C.G. , Van Loon L.C. , Ton Jurriaan , Pieterse Corné M.J.
Published: January 2008

Colonization of Arabidopsis thaliana roots by nonpathogenic Pseudomonas fluorescens WCS417r bacteria triggers a jasmonate/ethylene-dependent induced systemic resistance (ISR) that is effective against a broad range of pathogens. Microarray analysis revealed that the R2R3-MYB-like transcription factor gene MYB72 is specifically activated in the roots upon colonization by WCS417r. Here, we show that T-DNA knockout mutants myb72-1 and myb72-2 are incapable of mounting ISR against the pathogens Pseudomonas syringae pv tomato, Hyaloperonospora parasitica, Alternaria brassicicola, and Botrytis cinerea, indicating that MYB72 is essential to establish broad-spectrum ISR. Overexpression of MYB72 did not result in enhanced resistance against any of the pathogens tested, demonstrating that MYB72 is not sufficient for the expression of ISR. Yeast two-hybrid analysis revealed that MYB72 physically interacts in vitro with the ETHYLENE INSENSITIVE3 (EIN3)-LIKE3 transcription factor EIL3, linking MYB72 function to the ethylene response pathway. However, WCS417r activated MYB72 in ISR-deficient, ethylene-insensitive ein2-1 plants. Moreover, exogenous application of the ethylene precursor 1-aminocyclopropane-1-carboxylate induced wild-type levels of resistance in myb72-1, suggesting that MYB72 acts upstream of ethylene in the ISR pathway. Collectively, this study identified the transcriptional regulator MYB72 as a novel ISR signaling component that is required in the roots during early signaling steps of rhizobacteria-mediated ISR.
Job satisfaction and career persistence of beginning teachers
Authors: Mau Wei‐Cheng J. , Ellsworth Randy , Hawley Donna
Published: January 2008

Purpose

The purpose of this research is to examine career persistence and job satisfaction of beginning teachers. Design/methodology/approach – Four hundred and fifty‐one tenth grade students from a nationally representative sample, who aspired to be teachers, were examined over a ten year period regarding their career choices. Students who persisted in teaching were compared to students who did not persist with regard to job satisfaction. A job satisfaction model was tested using clusters of variables as guided by Social Cognitive Career Theory (SCCT).

Findings

Students who persisted in teaching were significantly more satisfied than both those who did not persist and those with non‐teaching careers. Beginning teachers were more satisfied with their jobs than those in other occupations. Teachers who had teaching licenses also reported being more satisfied than those who did not have licenses. The social‐contextual factors, i.e. race, socioeconomic status, teaching license, parents' education, and occupation were among the best predictors of job satisfaction. Research limitations/implications – We did not measure self‐efficacy directly. Instead, we used the separate yet highly correlated constructs, self‐concept and locus of control, to represent the self‐efficacy. For improvement, further research may use a more direct measure of self‐efficacy. Practical implications – Awareness of key factors influencing persistence in teaching career and job satisfaction identified in this study would provide school administrators with a sound basis for identifying students who are likely to persist in becoming teachers, and in retaining satisfied teachers. Originality/value – Findings of this study should assist educational administrators to better understand factors related to selection and retention of beginning teachers.
E‐government and service orientation: gaps between theory and practice
Authors: Åkesson Maria , Skålén Per , Edvardsson Bo
Published: January 2008

Purpose

The purpose of this paper is to review selected literature on e‐government service orientation and highlight differences between academic theory and empirical findings. To date, there has been little support for predictions made in the e‐government conceptual literature.

Design/methodology/approach

The paper is a conceptual framework for a literature review of e‐government and service orientation is presented. A systematic database search is then undertaken to identify the literature related to e‐government and service orientation. Suitable papers are selected, carefully read, and systematically analysed according to the conceptual framework. A discussion and relevant conclusions are then presented.

Findings

The paper finds that a gap appears to exist between conceptual literature and empirical findings. For example, conceptual research claims that e‐government will result in a reduction of staff, yet no empirical findings have proven this. The present study applies institutional theory for understanding the fundamental reasons to this gap.

Research limitations/implications

The paper is based on a literature review of 27 articles, three monographs and one edited volume focusing on service orientation and e‐government. It does not attempt to examine the full range of the literature available within the field of e‐government.

Originality/value

This review paper uniquely considers the gaps between the theory and practice of e‐government service orientation, and identifies where they exist. Some possible explanations for the gaps are explored which can be of interest to both academics and practitioners working in the field.
The antecedents of customer satisfaction with online travel services: a conceptual model
Authors: Nusair Khaldoon (Khal) , Kandampully Jay
Published: January 2008

Purpose

The purpose of this study is: to examine the travel web sites quality dimensions that ultimately influence customers' satisfaction; and to conduct content analyses on the five prominent travel web sites.

Design/methodology/approach

A content analysis was conducted on the six prominent travel web sites as ranked by J.D. Power Consumer Report. A list of 53 attributes were selected, named, and categorized around the six web quality dimensions explored in this study.

Findings

The findings of the content analysis provide evidence to suggest that online travel companies are underperforming in terms of providing web service quality attributes that enhance customer satisfaction.

Research limitations/implications

The focus of this study was only on the six prominent travel sites. However, the results cannot be generalized to all travel services. Additionally, only 53 attributes were extracted from the six web quality dimensions. There is a possibility that this study did not cover all the attributes that are part of the six dimensions.

Practical implications

Online travel companies can use the quality measurement tool developed in this study to detect service quality weaknesses and strengths. Moreover, travel businesses need to consider integrating features that make shopping experiences more enjoyable.

Originality/value

This study finding contributes to the present body of knowledge and also highlights web site quality dimensions that customers utilize in their assessment of overall online satisfaction.
Low‐tech, small‐ and medium‐sized enterprises and the practice of new product development
Authors: Lindman Martti , Scozzi Barbara , Otero‐Neira Carmen
Published: January 2008

Purpose

The purpose of this study is to examine the new product management practices adopted by low‐tech small and medium‐sized enterprises (SMEs) in the context of design‐intensive products.

Design/methodology/approach

The results are based on a multi‐case comparative setting covering SMEs in furniture industry in three countries, Italy, Spain and Finland.

Findings

The study shows considerable differences in performance that occur in terms of the degree of design and innovation, goal orientation and the systematics by which a single furniture business is managed. Proactiveness and freedom in design and innovation together with systematic new product development (NPD) and goal orientation enhances NPD performance. As to the new product uniqueness, innovative design is applicable in furniture industry much as in a similar way as new technological knowledge is in technology industries. The management education and/or interests which are closely related to furniture design and decoration have a clear impact on the level up to which innovative designs are implemented.

Practical implications

The study has direct implications for furniture companies aiming at improving their competitiveness and NPD effectiveness. The study points out the importance of creating a proper innovative culture and being open to new ideas if export markets are targeted.

Originality/value

Technology intensive products in large‐ and medium‐sized companies have been the main focus of NPD performance research, also facing the risk of over‐generalization due to cross‐industry approaches. Low‐tech industries however play a major role as to national income and employment. In this respect the present study aims to highlight the prevailing NPD practices in small design‐intensive firms in the furniture industry by reporting any management gaps which may occur in terms of new product performance.
Error compensation for fused deposition modeling (FDM) machine by correcting slice files
Authors: Tong Kun , Joshi Sanjay , Amine Lehtihet E.
Published: January 2008

Purpose

The purpose of this research is to extend the previous approach to software error compensation to fused deposition modeling (FDM) machines and explores the approach to apply compensation by correcting slice files.

Design/methodology/approach

In addition to applying the stereolithography (STL) file‐based compensation method from earlier research; a new approach using the slice file format to apply compensation is presented. Under this approach, the confounded effects of all errors in a FDM machine are mapped into a “virtual” parametric machine error model. A 3D artifact is built on the FDM machine and differences between its actual and nominal dimensions are used to estimate the coefficients of the error functions. A slice file compensation method is developed and tested on two types of parts as a means for further improving the error compensation for feature form error improvement. STL file compensation is also applied to a specific FDM 3000 machine and the results are compared with those of a specific SLA 250 machine.

Findings

The two compensation methods are compared. Although, the slice file compensation method theoretically allows higher compensation resolution, the actual machine control resolution of the FDM machine can be a limitation which makes the difference between STL compensation and slice file compensation indistinguishable. However, as the control resolution is increased, this method will make it possible to provide a higher degree of compensation.

Originality/value

Compensation method applied to slice file format is developed for FDM machines and its limitations are explored. Based on the experimental study, dimensional accuracy of parts is considerably improved by the software error compensation approach.
Achieving transformative sustainability learning: engaging head, hands and heart
Authors: Sipos Yona , Battisti Bryce , Grimm Kurt
Published: January 2008

Purpose

The current UN Decade of Education for Sustainable Development echoes many scholars' calls to re‐envision education for sustainability. Short of a complete overhaul of education, the paper seeks to propose learning objectives that can be integrated across existing curricula. These learning objectives are organized by head, hands and heart – balancing cognitive, psychomotor and affective domains. University programs and courses meeting these learning objectives exhibit an emergent property here termed transformative sustainability learning (TSL).

Design/methodology/approach

Theoretically, TSL grew from traditions of sustainability education and transformative education. Practically, TSL emerged from experimental learning collaborations sponsored by the University of British Columbia in 2003 and 2004 in an effort to enable explicit transitions to sustainability‐oriented higher education. Primarily through action research, these community‐based, applied learning experiences constituted cyclical processes of innovation, implementation and reflection.

Findings

The paper finds: advancement of head, hands and heart as an organizing principle by which to integrate transdisciplinary study (head); practical skill sharing and development (hands); and translation of passion and values into behaviour (heart); development of a cognitive landscape for understanding TSL as a unifying framework amongst related sustainability and transformative pedagogies that are inter/transdisciplinary, practical and/or place‐based; creation of learning objectives, organized to evaluate a course or program's embodiment of TSL.

Originality/value

By enabling change within existing structures of higher education, the paper complements and contributes to more radical departures from the institution. The work to date demonstrates potential in applying this learning framework to courses and programs in higher education.
BEHAVIOURAL ASPECTS OF ACCOUNTANCY
Authors: Vinten Gerald
Published: January 2008

Management accountants and auditors have much to learn from each other in how to minimise their respective problems. Any accounting system needs to pay due regard to individuals; groups; organisational structures and control; and the environment. Without this concern the accounting system will be seen as unrealistic and inadequate and this will lead to much of its information being ignored.
Reliability Analysis and Failure Cause Determination in Encapsulated Semiconductor Devices
Authors: Barry D.M.
Published: January 2008

This article describes reliability analysis and failure cause determination in encapsulated semiconductor devices. Such devices were subjected to a destructive life test using temperature as an accelerating stress. Once the devices had failed, the failure data were statistically analysed with the aid of a digital computer. The failed devices were then decapsulated and failure causes were determined using different types of microscopy. The article gives detailed information about the tests and analysis mentioned above.
A Review of the Literature On Quality‐Related Costs
Authors: Plunkett J.J. , Dale B.G.
Published: January 2008

A review of the literature of quality‐related costs indicates the domination of the prevention‐appraisal‐failure categorisation of costs, a similar pre‐occupation with in‐house costs and little consideration of supplier and customer‐related costs. Most of the data are of questionable value because not suitably qualified by detailing inclusions and methods of computation, and there is scant coverage of measurement and cost collection, or warnings of limitations in costing exercises. Failure to discuss definitions, and lack of guidance on cost collection and treatment of overheads and valuation of scrap are all notable omissions in the literature so far.