bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐organization and complexity in historical landscape patterns
Authors: Bolliger Janine , Sprott Julien C. , Mladenoff David J.
Published: March 2005

Self‐organization describes the evolution process of complex structures where systems emerge spontaneously, driven internally by variations of the system itself. Self‐organization to the critical state is manifested by scale‐free behavior across many orders of magnitude (Bak et al. 1987, Bak 1996, Solé et al. 1999). Spatial scale‐free behavior implies fractal properties and is quantified by the fractal dimension. Temporal scale‐free behavior is evident in power spectra of fluctuations that obey power laws. Self‐organized criticality is a universal phenomenon that likely produces some of the fractals and power laws observed in nature.

We investigated the historical landscape of southern Wisconsin (USA) (60,000 km2) for self‐organization and complexity. The landscape is patterned into prairies, savannas, and open and closed forests, using data from the United States General Land Office Surveys that were conducted during the 19th century, at a time prior to Euro‐American settlement.

We applied a two‐dimensional cellular automaton model with one adjustable parameter. Model evolution replaces a cell that dies at random times by a cell chosen randomly from within a circular radiusr, wherertypically takes values between 1 (local) and 10 units (regional). Cluster probability is used to measure the degree of organization. The model landscape self‐organizes to a realistic critical state if neighborhoods of intermediate size (r=3) are chosen, indicating that (a) no particular time or space scale for the clusters is singled out, i.e. the spatial dependence is fractal, and temporal fluctuations in the cluster probability exhibit power laws; (b) a simple model suffices to replicate the landscape pattern resulting from complex spatial and temporal interactions.

Measures of comparison between the observed and the simulated landscape show good agreement: fractal dimensions for simulated (1.6) and observed landscapes (1.64), cluster probabilities for simulated (32.3%) and observed (32.6%) landscapes, and algorithmic complexity for simulated (6792 bytes) and observed (6205 bytes) landscapes. The results are robust towards variation of initial and boundary conditions as well as perturbations.
Why ecology fails at application: should we consider variability more than regularity?
Authors: Hansson L.
Published: March 2005

Inability to solve applied ecological problems is argued to depend on inherent variability in intra‐ and interspecific interactions caused by individual utilisation of a variety of local environments, and on individual counter‐adaptations towards limiting or regulating factors. Such biological diversification is largely a response to environmental heterogeneity. Empirical and theoretical analyses of ecological mechanisms in various gradients of interaction and adaptation should result in improved use of ecological insight. Due to the many gradients, to the locally determined processes and to covert genetic variation very precise predictions of the outcome of ecological interactions will never be possible. Instead of focussing on possible general laws, ecology may try to establish common responses in population and community dynamics to main environmental gradients, particularly with regard to habitats and ecosystems.
The Many Shapes of Mitochondrial Membranes
Authors: Griparic Lorena , van der bliek Alexander M.
Published: March 2005

The roles of mitochondria in cell death and in aging have generated much excitement in recent years. At the same time, however, a quiet revolution in our thinking about mitochondrial ultrastructure has begun. This revolution started with the use of vital dyes and of green fluorescent protein fusion proteins, showing that mitochondria are very dynamic structures that constantly move, divide and fuse throughout the life of a cell. More recently, some of the first proteins contributing to these various processes have been discovered. Our view of the internal structures of mitochondria has also changed. Three‐dimensional reconstructions obtained with high voltage electron microscopy show that cristae are often connected to the mitochondrial inner membrane by thin tubules. These new insights are brought to bear on the wealth of data collected by conventional electron microscopic analysis.
Neuroradiologic findings in children with renal transplantation under 5 years of age
Authors: Valanne Leena , Qvist Erik , Jalanko Hannu , Holmberg Christer , Pihko Helena
Published: March 2005

Abstract:  Chronic renal failure (CRF) is known to have adverse effects on the neurodevelopmental outcome of affected children. Some of these effects can be ameliorated by transplantation (TX). The cause and nature of the underlying brain injury is not known. We performed a brain magnetic resonance imaging (MRI) study on a group of children after TX to look for brain abnormalities and, if possible, to draw conclusions about their origin. Thirty‐three children who received a renal allograft before 5 yr of age were studied. The most common diagnosis was the congenital nephrotic syndrome of Finnish type (29 patients). The male/female ratio was 22/11, the age range 6–11 yr. Pre‐TX CT studies of 26 patients were available for comparison. The patient files were studied for relevant clinical history, including pre‐ and perinatal events, infections, hypertension, hypertensive crises, hypovolemic states and medical emergencies. These risk factors were correlated with the MRI findings. Eighteen patients (54%) had ischemic lesions in the vascular border zones. Mild lesions were seen in 10 patients, moderate in six and severe in two patients. Other findings were rare, including infarcts in the main vascular territories and basal ganglia, and central and cortical atrophy. The pre‐TX CT's revealed border zone infarcts in six patients. Hemodynamic crises were reported in 14 patients and correlated well with border zone infarcts. The age at TX was greater and the duration of dialysis longer in those with border zone infarcts than in those without. Low gestational age, perinatal complications, and septic infections were not statistically significant risk factors. Because of the lack on serial imaging studies we do not know the exact timing of these brain infarcts. The good correlation to pre‐TX hemodynamic crises seems, however, to indicate that most of these lesions could be prevented by careful clinical monitoring and early TX.
Suppression of β1,3galactosyltransferase β3Gal‐T5 in cancer cells reduces sialyl‐Lewis a and enhances poly N‐acetyllactosamines and sialyl‐Lewis x on O‐glycans
Authors: Mare Lydia , Trinchera Marco
Published: March 2005

We investigated the role of β3Gal‐T5, a member of the β1,3galactosyltransferase (β1,3Gal‐T) family, in cancer‐associated glycosylation, focusing on the expression of sialyl‐Lewis a (sLea, the epitope of CA19.9 antigen), poly N‐acetyllactosamines, and sialyl‐Lewis x (sLex) antigen. A clone permanently expressing an antisense fragment of β3Gal‐T5 was obtained from the human pancreas adenocarcinoma cell line BxPC3 and characterized. Both β1,3Gal‐T activity and sLea expression are dramatically impaired in the clone. Analysis of the oligosaccharides synthesized in cells metabolically labelled with tritiated galactose shows that a relevant amount of radioactivity is associated to large O‐glycans. Endo‐β‐galactosidase mostly releases NeuAcα2‐3Galβ1‐3[Fucα1‐4]GlcNAcβ1‐3Gal and NeuAcα2‐3Galβ1‐3GlcNAcβ1‐3Gal from such O‐glycans of BxPC3 membranes, but GlcNAcβ1‐3Gal and type 2 chain oligosaccharides, including NeuAcα2‐3Galβ1‐4[Fucα1‐3]GlcNAcβ1‐3Gal, from those of the antisense clone. Furthermore, BxPC3 cells secrete sLea in the culture media but not sLex, while antisense clone secretes mostly sLex, and accumulation of both antigens is prevented by benzyl‐α‐GalNAc. These data indicate that β3Gal‐T5 suppression turns synthesis of type 1 chain O‐glycans to poly N‐acetyllactosamine elongation and termination by sLex. In other cell lines and clones, β3Gal‐T5 transcript, β1,3Gal‐T activity, and sLea antigen are also correlated, but quantitatively the relative expression ratios are very different from cell type to cell type. We suggest that β3Gal‐T5 plays a relevant role in gastrointestinal and pancreatic tissues counteracting the glycosylation pattern associated to malignancy, and is necessary for the synthesis and secretion of CA19.9 antigen, whose expression still depends on multiple interacting factors.
Investigation of photoreaction mechanism of photosensitive glass by femtosecond laser
Authors: Hongo Tomohiro , Sugioka Koji , Niino Hiroyuki , Cheng Ya , Masuda Masashi , Miyamoto Iwao , Takai Hiroshi , Midorikawa Katsumi
Published: March 2005

A high-intensity femtosecond (fs) laser can fabricate complicated three-dimensional microstructures inside photosensitive glass with high spatial resolution. In this work, the mechanism of the photoreaction of the photosensitive glass to the infrared fs laser is investigated. We examine the photoinduced electron excitation process on the basis of the determination of the critical dose and a change of the optical-absorption spectrum after the fs laser irradiation. The photoreaction mechanism is discussed in comparison with the case of an ultraviolet nanosecond laser irradiation. Finally, the successive interband electron excitation through defect levels by multiphoton absorption is proposed.
Dielectric nonlinearity of Pb(Yb1∕2Nb1∕2)O3–PbTiO3 thin films with {100} and {111} crystallographic orientation
Authors: Gharb N. Bassiri , Trolier-McKinstry S.
Published: March 2005

The extrinsic contributions to the dielectric response of 0.5Pb(Yb1∕2Nb1∕2)O3–0.5PbTiO3 thin films with (100) or (111) crystallographic orientation were studied (all indices are given in terms of the pseudocubic cell). Both the nonlinearity in the permittivity as well as the polarization hysteresis are described by the Rayleigh Law in subswitching conditions. It was found that (100) oriented films show a slightly higher extrinsic contribution to their dielectric behavior than (111) oriented films. For example, at 1 kHz and oscillation fields of 20kV∕cm, for (100) and (111) oriented films, respectively, 25% and 21% of the relative dielectric constant is due to irreversible extrinsic contributions. The difference is attributed to the higher concentration of mobile interfaces in the (100) oriented thin films. For frequencies between 20 Hz and 200 kHz both the Rayleigh parameters dropped with frequency approximately logarithmically. The frequency dependent Rayleigh parameters have been used to modify the Rayleigh Law to allow prediction of the dielectric properties in terms of both oscillation field and frequency.
Numerical treatment discussion and ab initio computational reinvestigation of physisorption of molecular hydrogen on graphene
Authors: Ferre-Vilaplana A.
Published: March 2005

A numerical treatment suitable for the computational investigation of physisorption of molecular hydrogen on carbon nanostructures has not been sufficiently discussed. In this paper it is shown that results used as a reference are actually a product of poorly solved interactions and contaminated estimates with errors which would be of the order of 60%. Moreover, using ab initio molecular orbital theory, under the rigid monomer supermolecular approach, the physisorption energy of molecular hydrogen on graphene was reinvestigated. The graphene surface was modeled as a coronenelike (C24H12) graphene sheet. The basis set superposition error was corrected by means of the counterpoise method. The H2–H2 and H2-benzene interactions were examined, under systematic combinations of basis sets and correlation methods, including the aug-cc-pVQZ basis set and the coupled cluster correlation method with single, double, and noniterative triple excitations, searching for a numerical treatment with a reasonable trade-off between efficiency and accuracy. Asymmetrical modeling strategies, using diffusion augmented basis sets with preference for the adsorbate, were found to be effective. Also local modeling strategies, using more complete basis sets for the nearest atoms to the adsorbate than for the rest of the substrate, were considered. The aug-cc-pVTZ basis set for the adsorbate and for the nearest atoms to the adsorbate and the cc-pVTZ basis set for the rest of the cluster-modeled graphene, at the second-order Möller–Plesset perturbation theory correlation level, was selected as reference treatment. It was found that the physisorption energy of molecular hydrogen on graphene would be of the order of 0.06 eV, which would be 25% less than what has been previously published, though it would be sufficient to permit the storage of hydrogen physisorbed on carbon. To our knowledge this would be the most realistic theoretical estimate of the mentioned energy to date.
Study of the enhanced thermal conductivity of Fe nanofluids
Authors: Hong Tae-Keun , Yang Ho-Soon , Choi C. J.
Published: March 2005

Nanofluids, a mixture of nanoparticles and fluid, have enormous potential to improve the efficiency of heat transfer fluids. Fe nanofluids are prepared with ethylene glycol and Fe nanocrystalline powder synthesized by a chemical vapor condensation process. Sonication with high-powered pulses is used to improve the dispersion of nanoparticles in the preparation of nanofluids. Nanofluids exhibit an enhancement of thermal conductivity after sonication. Thermal conductivity of a Fe nanofluid is increased nonlinearly up to 18% as the volume fraction of particles is increased up to 0.55 vol. %. Comparing Fe nanofluids with Cu nanofluids, we find that the suspension of highly thermally conductive materials is not always effective to improve thermal transport property of nanofluids.
Optical Properties of 3,4,9,10-perylenetetracarboxylic dianhydride/copper phthalocyanine superlattices
Authors: Gordan O. D. , Hermann S. , Friedrich M. , Zahn D. R. T.
Published: March 2005

Organic superlattices consisting of five alternating layers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and copper phthalocyanine (CuPc) were prepared by organic molecular-beam deposition in high vacuum on hydrogen-passivated, (111)-oriented silicon. The substrates were kept at room temperature during the deposition. The optical response of the multilayered structure was investigated by means of spectroscopic ellipsometry in the spectral range from 0.73 to 5eV. While the infrared spectra show that there is no chemical interaction between the two pigments, the ellipsometry evaluation suggests an electronic coupling between the π orbitals of the PTCDA and the π orbitals of the CuPc. This means that the modeling of the optical response requires a more sophisticated approach than simply superimposing the responses of the individual layers.
Conductance measurement of a DNA network in nanoscale by point contact current imaging atomic force microscopy
Authors: Terawaki Ayumu , Otsuka Yoichi , Lee HeaYeon , Matsumoto Takuya , Tanaka Hidekazu , Kawai Tomoji
Published: March 2005

We measured the electrical conductivity of a DNA network as a spatially-resolved current-image using point-contact current imaging atomic force microscopy (PCI-AFM) under various humidity conditions. The simultaneous observation of topography and current image by PCI-AFM can provide information pertaining to the electrical properties of biological and∕or soft materials in the nano-scale range. Under dry condition (0% humidity), no difference was observed for the electrical current both of the DNA network and mica surface, whereas the electrical current along the DNA network was larger than that of the mica surface by 20pA at a bias voltage of 5V under high humidity conditions of 60%.
Measurement of subband electronic temperatures and population inversion in THz quantum-cascade lasers
Authors: Vitiello Miriam S. , Scamarcio Gaetano , Spagnolo Vincenzo , Williams Benjamin S. , Kumar Sushil , Hu Qing , Reno John L.
Published: March 2005

We compare the electronic temperatures and the population inversion both below and above the lasing threshold in three quantum-cascade lasers (QCLs) operating at 2.8THz, 3.2THz, and 3.8THz using microprobe band-to-band photoluminescence. In the lasing range, while the ground-state temperature remains close to the lattice one (90K–100K), the upper radiative state heats up to ∼200K. From the measured thermal resistance and the power dependence of the ground-state electronic temperature, we get a value of the electron-lattice energy relaxation rate comparable with that typical of midinfrared QCLs.
X-ray absorption near-edge fine structure study of AlInN semiconductors
Authors: Guo Qixin , Ding Jian , Tanaka Tooru , Nishio Mitsuhiro , Ogawa Hiroshi
Published: March 2005

We have carried out the x-ray absorption near-edge fine structure (XANES) measurements of AlInN at AlK edge and the self-consistent-field real-space multiple-scattering theory calculations. It was demonstrated that the AlK-edge XANES spectra of AlInN are the fingerprints of their composition. The theoretical results could give a reasonable reproduction of the experimental spectral structures. This type of combined use of the experimental XANES and the theoretical calculations must be a powerful tool for systematic and qualitative analysis of the structural and electronic structures of nitride semiconductors.
Recognition without Perceptual Identification: A Measure of Familiarity?
Authors: Cleary Anne M. , Greene Robert L.
Published: March 2005

Previous work has shown that when items in a perceptual identification task are presented too quickly to identify, participants can still discriminate between studied and unstudied items. Such recognition without perceptual identification (RWPI) has been shown to occur in a variety of situations, including the false recognition of semantic associates of studied items. The present study investigated the utility of the RWPI paradigm for isolating instances of recognition that are familiarity based from those that are recollection based. Toward this end, the magnitude of the RWPI effect was compared in item versus associative recognition and in short versus long lists. The RWPI effect was larger in item than in associative recognition, and larger with short than with long study lists. These results are interpreted within the context of a dual-process approach to recognition and support the notion that RWPI taps familiarity-based recognition.
Dynamic Sorting of Nuclear Components into Distinct Nucleolar Caps during Transcriptional Inhibition
Authors: Shav-Tal Yaron , Blechman Janna , Darzacq Xavier , Montagna Cristina , Dye Billy T. , Patton James G. , Singer Robert H. , Zipori Dov
Published: March 2005

Nucleolar segregation is observed under some physiological conditions of transcriptional arrest. This process can be mimicked by transcriptional arrest after actinomycin D treatment leading to the segregation of nucleolar components and the formation of unique structures termed nucleolar caps surrounding a central body. These nucleolar caps have been proposed to arise from the segregation of nucleolar components. We show that contrary to prevailing notion, a group of nucleoplasmic proteins, mostly RNA binding proteins, relocalized from the nucleoplasm to a specific nucleolar cap during transcriptional inhibition. For instance, an exclusively nucleoplasmic protein, the splicing factor PSF, localized to nucleolar caps under these conditions. This structure also contained pre-rRNA transcripts, but other caps contained either nucleolar proteins, PML, or Cajal body proteins and in addition nucleolar or Cajal body RNAs. In contrast to the capping of the nucleoplasmic components, nucleolar granular component proteins dispersed into the nucleoplasm, although at least two (p14/ARF and MRP RNA) were retained in the central body. The nucleolar caps are dynamic structures as determined using photobleaching and require energy for their formation. These findings demonstrate that the process of nucleolar segregation and capping involves energy-dependent repositioning of nuclear proteins and RNAs and emphasize the dynamic characteristics of nuclear domain formation in response to cellular stress.
Legitimacy and Meaning: The Significance of Public Debate to the Adoption of the Constitution
Authors: Edling Max. M
Published: March 2005

Argues that the role of debate in the struggle over ratification was significant to the adoption of the US Constitution because public debate was a necessary step in the decision‐making process leading to its ratification. It was a necessary step because adoption would not have been legitimate without the possibility of public debate, but the debate was also significant in another way: it provided the first widely shared and detailed interpretation of important clauses of the Constitution. This original elucidation of the meaning of the Constitution later served as the point of origin for constitutional interpretation in the political life of the early republic – an authoritative source for establishing the meaning of the Constitution.
The Federalists and the Uses of Military Powers
Authors: Edling Max. M
Published: March 2005

Chapter 9 and the corresponding Ch. 14 in Part Three of the book offer brief sketches of the institutionalization of the military and fiscal powers granted by the US Constitution, and of the uses made of them by the Federalists in the 1790s. Gives a historical account of the uses made by the national government during that period of the military powers that it was granted by the Constitution. Aims to make a judgment on the political achievement of the Federalists that hinges on the extent to which they managed to translate their principles into action when they transformed the articles of the Constitution into the policies and institutions of the new national government. Part of the discussion also addresses the fact that during the quarter century following the First US Congress, the USA had to respond repeatedly to events originating in Europe far beyond the federal government's control, and overall, drew advantage from the warfare that engulfed Britain, France, and Spain. It is noted that is not easy to answer the question of whether the federal government had any part in making this possible, but a cautious answer based on works of diplomatic history is that the reform of the federal government did make a difference to the actions of European governments.
CRISPR elements in Yersinia pestis acquire new repeats by preferential uptake of bacteriophage DNA, and provide additional tools for evolutionary studies
Authors: Pourcel C. , Salvignol G. , Vergnaud G.
Published: March 2005

The remarkable repetitive elements called CRISPRs (clustered regularly interspaced short palindromic repeats) consist of repeats interspaced with non-repetitive elements or ‘spacers’. CRISPRs are present in both archaea and bacteria, in association with genes involved in DNA recombination and repair. In the Yersinia pestis genome, three such elements are found at three distinct loci, one of them being highly polymorphic. The authors have sequenced a total of 109 alleles of the three Y. pestis CRISPRs and they describe 29 new spacers, most being specific to one isolate. In nine strains of Yersinia pseudotuberculosis, 132 spacers were found, of which only three are common to Y. pestis isolates. In Y. pestis of the Orientalis biovar investigated in detail here, deletion of motifs is observed but it appears that addition of new motifs to a common ancestral element is the most frequent event. This takes place at the three different loci, although at a higher rate in one of the loci, and the addition of new motifs is polarized. Interestingly, the most recently acquired spacers were found to have a homologue at another locus in the genome, the majority of these inside an inactive prophage. This is believed to be the first time that the origin of the spacers in CRISPR elements has been explained. The CRISPR structure provides a new and robust identification tool.
Functional analysis and annotation of the virulence plasmid pMUM001 from Mycobacterium ulcerans
Authors: Stinear Timothy P. , Pryor Melinda J. , Porter Jessica L. , Cole Stewart T.
Published: March 2005

The presence of a 174 kb plasmid called pMUM001 in Mycobacterium ulcerans, the first example of a mycobacterial plasmid encoding a virulence determinant, was recently reported. Over half of pMUM001 is devoted to six genes, three of which encode giant polyketide synthases (PKS) that produce mycolactone, an unusual cytotoxic lipid produced by M. ulcerans. In this present study the remaining 75 non-PKS-associated protein-coding sequences (CDS) are analysed and it is shown that pMUM001 is a low-copy-number element with a functional ori that supports replication in Mycobacterium marinum but not in the fast-growing mycobacteria Mycobacterium smegmatis and Mycobacterium fortuitum. Sequence analyses revealed a highly mosaic plasmid gene structure that is reminiscent of other large plasmids. Insertion sequences (IS) and fragments of IS, some previously unreported, are interspersed among functional gene clusters, such as those genes involved in plasmid replication, the synthesis of mycolactone, and a potential phosphorelay signal transduction system. Among the IS present on pMUM001 were multiple copies of the high-copy-number M. ulcerans elements IS2404 and IS2606. No plasmid transfer systems were identified, suggesting that trans-acting factors are required for mobilization. The results presented here provide important insights into this unusual virulence plasmid from an emerging but neglected human pathogen.
Dynamic localization of penicillin-binding proteins during spore development in Bacillus subtilis
Authors: Scheffers Dirk-Jan
Published: March 2005

DuringBacillus subtilisspore formation, many membrane proteins that function in spore development localize to the prespore septum and, subsequently, to the outer prespore membrane. Recently, it was shown that the cell-division-specific penicillin-binding proteins (PBPs) 1 and 2b localize to the asymmetric prespore septum. Here, the author studied the localization of other PBPs, fused to green fluorescent protein (GFP), during spore formation. Fusions to PBPs 4, 2c, 2d, 2a, 3, H, 4b, 5, 4a, 4* and X were expressed during vegetative growth, and their localization was monitored during sporulation. Of these PBPs, 2c, 2d, 4b and 4* have been implicated as having a function in sporulation. It was found that PBP2c, 2d and X changed their localization, while the other PBPs tested were not affected. The putative endopeptidase PbpX appears to spiral out in a pattern that resembles FtsZ redistribution during sporulation, but apbpXknockout strain had no distinguishable phenotype. PBP2c and 2d localize to the prespore septum and follow the membrane during engulfment, and so are redistributed to the prespore membrane. A similar pattern was observed when GFP–PBP2c was expressed in the mother cell from a sporulation-specific promoter. This work shows that various PBPs known to function during sporulation are redistributed from the cytoplasmic membrane to the prespore.
The Mycorrhizal Fungus Gigaspora margarita Possesses a CuZn Superoxide Dismutase That Is Up-Regulated during Symbiosis with Legume Hosts
Authors: Lanfranco Luisa , Novero Mara , Bonfante Paola
Published: March 2005

A full-length cDNA showing high similarity to previously described CuZn superoxide dismutases (SODs) was identified in an expressed sequence tag collection from germinated spores of the arbuscular mycorrhizal fungus Gigaspora margarita (BEG 34). The corresponding gene sequence, named GmarCuZnSOD, is composed of four exons. As revealed by heterologous complementation assays in a yeast mutant, GmarCuZnSOD encodes a functional polypeptide able to confer increased tolerance to oxidative stress. The GmarCuZnSOD RNA was differentially expressed during the fungal life cycle; highest transcript levels were found in fungal structures inside the roots as observed on two host plants, Lotus japonicus and Medicago truncatula. These structures also reacted positively to 3,3′-diaminobenzidine, used to localize H2O2 accumulation. This H2O2 is likely to be produced by CuZnSOD activity since treatment with a chelator of copper ions, generally used to inhibit CuZnSODs, strongly reduced the 3,3′-diaminobenzidine deposits. A slight induction of GmarCuZnSOD gene expression was also observed in germinated spores exposed to L. japonicus root exudates, although the response showed variation in independent samples. These results provide evidence of the occurrence, in an arbuscular mycorrhizal fungus, of a functional SOD gene that is modulated during the life cycle and may offer protection as a reactive oxygen species-inactivating system against localized host defense responses raised in arbuscule-containing cells.
Lotus japonicus Metabolic Profiling. Development of Gas Chromatography-Mass Spectrometry Resources for the Study of Plant-Microbe Interactions
Authors: Desbrosses Guilhem G. , Kopka Joachim , Udvardi Michael K.
Published: March 2005

Symbiotic nitrogen fixation (SNF) in legume root nodules requires differentiation and integration of both plant and bacterial metabolism. Classical approaches of biochemistry, molecular biology, and genetics have revealed many aspects of primary metabolism in legume nodules that underpin SNF. Functional genomics approaches, especially transcriptomics and proteomics, are beginning to provide a more holistic picture of the metabolic potential of nodules in model legumes like Medicago truncatula and Lotus japonicus. To extend these approaches, we have established protocols for nonbiased measurement and analysis of hundreds of metabolites from L. japonicus, using gas chromatography coupled with mass spectrometry. Following creation of mass spectral tag libraries, which represent both known and unknown metabolites, we measured and compared relative metabolite levels in nodules, roots, leaves, and flowers of symbiotic plants. Principal component analysis of the data revealed distinct metabolic phenotypes for the different organs and led to the identification of marker metabolites for each. Metabolites that were enriched in nodules included: octadecanoic acid, asparagine, glutamate, homoserine, cysteine, putrescine, mannitol, threonic acid, gluconic acid, glyceric acid-3-P, and glycerol-3-P. Hierarchical cluster analysis enabled discrimination of 10 groups of metabolites, based on distribution patterns in diverse Lotus organs. The resources and tools described here, together with ongoing efforts in the areas of genome sequencing, and transcriptome and proteome analysis of L. japonicus and Mesorhizobium loti, should lead to a better understanding of nodule metabolism that underpins SNF.
Molecular Basis of Evolutionary Events That Shaped theHardnessLocus in Diploid and Polyploid Wheat Species (Triticum and Aegilops)
Authors: Chantret Nathalie , Salse Jérôme , Sabot François , Rahman Sadequr , Bellec Arnaud , Laubin Bastien , Dubois Ivan , Dossat Carole , Sourdille Pierre , Joudrier Philippe , Gautier Marie-Françoise , Cattolico Laurence , Beckert Michel , Aubourg Sébastien , Weissenbach Jean , Caboche Michel , Bernard Michel , Leroy Philippe , Chalhoub Boulos
Published: March 2005

The Hardness (Ha) locus controls grain hardness in hexaploid wheat (Triticum aestivum) and its relatives (Triticum and Aegilops species) and represents a classical example of a trait whose variation arose from gene loss after polyploidization. In this study, we investigated the molecular basis of the evolutionary events observed at this locus by comparing corresponding sequences of diploid, tertraploid, and hexaploid wheat species (Triticum and Aegilops). Genomic rearrangements, such as transposable element insertions, genomic deletions, duplications, and inversions, were shown to constitute the major differences when the same genomes (i.e., the A, B, or D genomes) were compared between species of different ploidy levels. The comparative analysis allowed us to determine the extent and sequences of the rearranged regions as well as rearrangement breakpoints and sequence motifs at their boundaries, which suggest rearrangement by illegitimate recombination. Among these genomic rearrangements, the previously reported Pina and Pinb genes loss from the Ha locus of polyploid wheat species was caused by a large genomic deletion that probably occurred independently in the A and B genomes. Moreover, the Ha locus in the D genome of hexaploid wheat (T. aestivum) is 29 kb smaller than in the D genome of its diploid progenitor Ae. tauschii, principally because of transposable element insertions and two large deletions caused by illegitimate recombination. Our data suggest that illegitimate DNA recombination, leading to various genomic rearrangements, constitutes one of the major evolutionary mechanisms in wheat species.
The MutantcrispaReveals Multiple Roles forPHANTASTICAin Pea Compound Leaf Development
Authors: Tattersall Alexander D. , Turner Lynda , Knox Margaret R. , Ambrose Michael J. , Ellis T.H. Noel , Hofer Julie M.I.
Published: March 2005

Pinnate compound leaves have laminae called leaflets distributed at intervals along an axis, the rachis, whereas simple leaves have a single lamina. In simple- and compound-leaved species, the PHANTASTICA (PHAN) gene is required for lamina formation. Antirrhinum majus mutants lacking a functional gene develop abaxialized, bladeless adult leaves. Transgenic downregulation of PHAN in the compound tomato (Solanum lycopersicum) leaf results in an abaxialized rachis without leaflets. The extent of PHAN gene expression was found to be correlated with leaf morphology in diverse compound-leaved species; pinnate leaves had a complete adaxial domain of PHAN gene expression, and peltate leaves had a diminished domain. These previous studies predict the form of a compound-leaved phan mutant to be either peltate or an abaxialized rachis. Here, we characterize crispa, a phan mutant in pea (Pisum sativum), and find that the compound leaf remains pinnate, with individual leaflets abaxialized, rather than the whole leaf. The mutant develops ectopic stipules on the petiole-rachis axis, which are associated with ectopic class 1 KNOTTED1-like homeobox (KNOX) gene expression, showing that the interaction between CRISPA and the KNOX gene PISUM SATIVUM KNOTTED2 specifies stipule boundaries. KNOX and CRISPA gene expression patterns indicate that the mechanism of pea leaf initiation is more like Arabidopsis thaliana than tomato.
Phototropins Promote Plant Growth in Response to Blue Light in Low Light Environments
Authors: Takemiya Atsushi , Inoue Shin-ichiro , Doi Michio , Kinoshita Toshinori , Shimazaki Ken-ichiro
Published: March 2005

Phototropins (phot1 and phot2) are plant-specific blue light receptors for phototropism, chloroplast movement, leaf expansion, and stomatal opening. All these responses are thought to optimize photosynthesis by helping to capture light energy efficiently, reduce photodamage, and acquire CO2. However, experimental evidence for the promotion of plant growth through phototropins is lacking. Here, we report dramatic phototropin-dependent effects on plant growth. When plants of Arabidopsis thaliana wild type, the phot1 and phot2 mutants, and the phot1 phot2 double mutant were grown under red light, no significant growth differences were observed. However, if a very low intensity of blue light (0.1 μmol m−2 s−1) was superimposed on red light, large increases in fresh weight up to threefold were found in those plants that carried functional PHOT1 genes. When the intensity of blue light was increased to 1 μmol m−2 s−1, the growth enhancement was also found in the phot1 single mutant, but not in the double mutant, indicating that phot2 mediated similar responses as phot1 with a lower sensitivity. The effects occurred under low photosynthetically active radiation in particular. The well-known physiological phototropin-mediated responses, including chloroplast movement, stomatal opening, and leaf expansion, in the different lines tested indicated an involvement of these responses in the blue light–induced growth enhancement. We conclude that phototropins promote plant growth by controlling and integrating a variety of responses that optimize photosynthetic performance under low photosynthetically active radiation in the natural environment.
Linear stability analysis of long journal bearings: couple stress fluid model
Authors: Liao Won‐Hsion , Lu Rong‐Fang , Chien Rean‐Der , Lin Jaw‐Ren
Published: March 2005

Purpose

The purpose of the present study is to provide the dynamic characteristics of long journal bearings lubricated with couple stress fluids.

Design/methodology/approach

Based upon the micro‐continuum theory generated by Stokes, the dynamic Reynolds‐type equation governing the film pressure is derived to account for the couple stress effects resulting from the non‐Newtonian behavior of complex fluids. By applying the linear stability theory to the non‐linear equations of motion the journal rotor, the equilibrium positions and dynamic characteristics of the system are evaluated.

Findings

As compared to the classical Newtonian model, the effects of couple stresses signify enhanced stiffness and damping coefficients (including KXX, KXY , BXX and BXY) at moderate values of the steady eccentricity ratio. Totally, as the rotor center operates at an eccentricity ratio about εs≤0.71, long bearings lubricated with couple stress fluids under small disturbance results in a higher stability threshold speed than that of the Newtonian‐lubricant case.

Originality/value

These findings provide engineers useful information in designing journal‐bearing systems.
Influences of recess depth on the stability of the Jeffcott rotor supported by hybrid bearings with orifice restrictors
Authors: Chen Cheng‐Hsien , Kang Yuan , Chang Yeon‐Pun , Lee Hsing‐Han , Shen Ping‐Chen
Published: March 2005

Purpose

The present paper proposes a theoretical analysis of the stability characteristics of a Jeffcott rotor‐hybrid bearing system. It is intended that on the basis of the numerical results drawn from this study, appropriate recess depth, land size, orifice location and speed parameter for stable operation can be determined for use in the bearing design process.

Design/methodology/approach

A Jeffcott rotor supported by hybrid oil film bearings with dual‐row recesses and orifice‐ compensated restrictors is studied. In order to facilitate the calculation of film dynamics, using the perturbation method, the Reynolds equation was linearized and subsequently solved using finite difference techniques, whilst the stability maps were determined by the Routh‐Hurwitz method.

Findings

The data reported here suggest that the stability characteristics of the Jeffcott rotor‐bearing system could be improved by the use of shallow, dual‐recessed hybrid bearings with orifice compensation. In addition to greater eccentricity ratios, smaller land‐width ratios and greater shaft stiffness may also provide shallow‐recessed bearings with better stability. In all cases, the stability provided by upstream orifice‐sited bearings is better than that provided by center orifice‐sited bearings, whilst high‐speed parameters may also provide a greater stability threshold.

Originality/value

This study proposes an extensive database as a critical requirement in the design of hybrid bearings, in order to ensure that a rotor bearing system is operating stably.
An examination of the general decision making style questionnaire in two UK samples
Authors: Spicer David P. , Sadler‐Smith Eugene
Published: March 2005

Purpose

To examine the psychometric properties and construct validity of the general decision making style (GDMS) questionnaire in two UK samples.Design/methodology/approach – The GDMS takes the form of a self‐report questionnaire which identifies five decision making styles: rational, intuitive, dependent, avoidant, and spontaneous. It was administered to samples of business studies undergraduates in two UK business schools. Analyses included scale reliabilities, test‐re‐test reliability, and both exploratory and confirmatory factor analyses.Findings – The instrument's internal and temporal consistencies were generally sound. Consistent with earlier studies, analyses undertaken on the two samples independently were generally supportive of a five factor model of decision making style. No relationships with gender or year of study were observed.Research limitations/implications – Whilst generally supportive of the GDMS, results suggest that further validation work is required. This could include consideration of the relationships between the GDMS and other measures of cognitive/personality style.Practical implications – The managerial implications of the strengths of and relationships between the different decision making styles observed are discussed.Originality/value – The paper fulfils a stated requirement for further validation study of the GDMS instrument.
Engaging customers in service creation: a theater perspective
Authors: Williams Jacqueline A. , Anderson Helen H.
Published: March 2005

Purpose

A theater/drama perspective is used to gain insights into the participatory nature of service creation and to assess the relative importance of service elements across service scenarios.

Design/methodology/approach

Drama production principles are applied to situations where customers co‐create the service offering. Using a theater arts model, elements in service settings can be delineated into director, lead actor, set designer, scriptwriter, supporting cast member, and/or traditional audience roles. To understand the relative importance of the service provider, the customer, and other service encounter elements, three variations of a service setting (educational services) in which the consumer's participatory role moves from passive to proactive are compared.

Findings

As the service context became more participatory‐based, service provider roles significantly decreased in importance rankings while customer roles significantly increased, supporting the paper's hypotheses. The ranking of other service setting elements followed a similar pattern with greater importance being placed on elements as they became more central to the participatory experience.

Research limitations/implications

The model is tested in only one service setting and the procedure for assigning theater roles to a service setting needs further refinement.

Originality/value

By merging theories from theater and services literature, a means of assessing the relative importance of service components across service scenarios is illustrated. Principles in theater arts provide the tactical detail needed to fit service creation elements into analogous roles in a drama setting. The model provides insights on the importance of service creation elements when transitioning from a spectator‐based to a participatory‐based service environment.
Design and implementation of a service guarantee
Authors: Fabien Louis
Published: March 2005

Purpose

To propose a decision support model that can be used to design, implement and communicate effective and efficient service guarantees.

Design/methodology/approach

Based on in‐depth interviews by the author and on a recent literature review, the author has looked at different issues regarding service guarantees developed by services companies over the last five years.

Findings

The decision support model looks first at 12 key issues to examine before designing a service guarantee. If the preliminary analysis is conclusive, discussion about design and implementation is presented.

Originality/value

The main and original contribution of this model is to present to services marketing managers a step‐by‐step process, including preliminary analysis, marketing communication and performance analysis.
The impact of mode of operation on sales performance in international services
Authors: Kirca Ahmet H.
Published: March 2005

Purpose

To investigate the impact of current mode of operation on service firms’ sales performance in international markets, and to examine the role of managerial control as a mediator of the mode of operation‐sales performance relationship.

Design/methodology/approach

A conceptual framework and a set of hypotheses were developed to posit that managerial control on marketing activities act as a process variable between the level of vertical integration of the mode of operation and firm success in international markets. The proposed hypotheses were tested using regression analysis with data from a sample of tour operators from Turkey.

Findings

The choice of mode of operation is a critical decision that impacts the performance of service firms in international markets, such that firms which use more vertically integrated modes of operation obtain higher sales performance as a result of their high levels of control on marketing activities.

Research limitations/implications

Although the present findings can be generalized to other soft service industries such as consulting, accommodation services, and health care, they provide limited insights for hard service industries (i.e. construction, insurance, banking and financial services).

Practical implications

This article offers guidance in the internationalization process of service firms by highlighting the importance of managerial control on marketing activities as a factor that should be considered in reviewing and evaluating alternative modes of operation in foreign markets.

Originality/value

This study contributes to the extant research by testing one of the basic assumptions of the mode of entry literature: the relationship between vertical integration and managerial control. Also, the findings reveal that the level of vertical integration of the mode of operation is positively related to performance because vertical integration provides service firms with managerial control.
The collaboration index: a measure for supply chain collaboration
Authors: Simatupang Togar M. , Sridharan Ramaswami
Published: March 2005

Purpose

This paper proposes an instrument to measure the extent of collaboration in a supply chain consisting of two members, suppliers and retailers.

Design/methodology/approach

The proposed model for collaboration incorporates collaborative practices in information sharing, decision synchronisation and incentive alignment. A collaboration index is introduced to measure the level of collaborative practices. A survey of companies in New Zealand was conducted to obtain data to test and evaluate the collaboration index.

Findings

The survey results confirmed the reliability and validity of the proposed collaboration index measure for measuring collaboration. The findings also showed that the collaboration index was positively associated with operational performance.

Research limitations/implications

Future research could consider larger sample sizes and cover other industry types.

Practical implications

Supply chain participants will be able to measure the extent of their collaboration and seek improvement in their performance.

Originality/value

This paper contributes to the literature by introducing a new index for measuring the extent of supply chain collaboration. This measure can be used by any participant (member) in a supply chain to identify the level of collaboration and seek improvement.