bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of the Rydberg electron in H*+D2→D*+HD reactive collisions
Authors: Hayes Michael Y. , Skodje Rex T.
Published: March 2007

Experimental crossed-beam studies carried out previously have indicated that the dynamics of the Rydberg-atom-molecule reaction H*+D2→D*+HD are very similar to those of the corresponding ion-molecule reaction H++D2→D++HD. The equivalence of the cross sections for these related systems would open up a new approach to the experimental study of ion-molecule reactions. However, a recent experimental and theoretical study has brought to light some important qualitative differences between the Rydberg-atom reaction and the ion-molecule reaction; in particular, the experimental cross section for the Rydberg-atom reaction exhibits a higher degree of forward-backward scattering asymmetry than predicted by a quasiclassical trajectory study of the ion-molecule reaction. In this paper, the authors consider the dynamics of the Rydberg-electron over the course of a reactive collision and the implications of these dynamics for the Rydberg-atom-molecule crossed-beam experiment. Using an approach based on perturbation theory, they estimate the attenuation of the experimental signal due to the Rydberg-electron dynamics as a function of the scattering angle. They show that at least part of the experimental asymmetry can be ascribed to this angle dependent attenuation. Their results offer general insight into the practical aspects of the experimental study of ion-molecule reactions by means of their Rydberg-atom counterparts.
Are dipolar liquids ferroelectric? Simulation studies
Authors: Pounds Michael A. , Madden Paul A.
Published: March 2007

The observation of a very sharp low frequency spike in the hyper-Rayleigh spectrum (HRS) of strongly dipolar fluids, such as acetonitrile and water, has been interpreted as reflecting a very slowly relaxing component in the transverse dipole density. This suggestion is at variance with the expectation of the dielectric theory for an isotropic fluid and has led to the speculation that the slow relaxation is associated with the reorganization of ferroelectric domains. Very large-scale molecular-dynamics simulation (∼28 000 molecules) have been carried out using a three-site potential model of acetonitrile. The simulated fluid shows no suggestion of strong dipole correlations and domain structure. The dipole density correlations behave as predicted by the normal dielectric theory and their spectra do not show the low-frequency feature seen in the HRS. In order to examine the characteristics of the spectra which would be seen in a ferroelectric domain, the acetontrile model was transmuted to more closely resemble a Stockmayer-type fluid with the same dipole density and a ferroelectric phase was observed. In this phase the dielectric spectra show (i) a high-frequency spectral feature due to librational motion of the molecules within a domain, and (ii) slowly-relaxing longitudinal and transverse polar modes, again at variance from the experimental HRS characteristics.
Free energy simulations of single and double ion occupancy in gramicidin A
Authors: Baştuğ Turgut , Kuyucak Serdar
Published: March 2007

Simultaneous occupancy of the two binding sites in gramicidin A by monovalent cations is a well known property of this channel, but the energetic feasibility of this process in molecular dynamics simulations has not been established so far. Here the authors study the energetics of single and double ion occupancy in gramicidin A by constructing the potential of mean force for single and pair of cations. As representatives of small and large ions, they consider both Na+ and K+ ions in the calculations. Binding constants of ions are estimated from the free energy profiles. Comparisons with the experimental results indicate 3–4kT discrepancy in the binding energies. They also study the coordination of the ions in their respective binding sites and the dynamic behavior of the channel water during the double ion binding process.
Dynamic Grouping and Interpolation Induced by Flickering Stimuli
Authors: Sasaki Hiroyuki
Published: March 2007

A novel grouping and interpolation effect induced by flickering stimuli is described: a matrix of flickering elements forms stick-like clusters, then the clusters gradually dissociate back into the discrete elements within a few seconds. On continuous viewing, this flicker-induced grouping and interpolation repeatedly disappeared and reappeared. The perceived strength of this phenomenon peaked when the luminance of the flickering elements was alternately darker and lighter than the background; thus, the reversal of the luminance contrast polarity was responsible for flicker-induced grouping. The temporal dynamics of flicker-induced grouping showed the stochastic nature of perceptual alternation, which depended on the global structure of the stimulus. From these results, it is concluded that flicker-induced grouping reflects multiple stages of visual processing.
Simultaneous reduction of iron–sulfur protein and cytochrome
b
L
during ubiquinol oxidation in cytochrome
bc
1
complex
Authors: Zhu Jian , Egawa Tsuyoshi , Yeh Syun-Ru , Yu Linda , Yu Chang-An
Published: March 2007

The key step of the protonmotive Q-cycle mechanism of the cytochrome
bc
1
complex is the bifurcated oxidation of ubiquinol at the Qp site. It was postulated that the iron–sulfur protein (ISP) accepts the first electron from ubiquinol to generate ubisemiquinone anion to reduce
b
L
. Because of the difficulty of following the reduction of ISP optically, direct evidence for the early involvement of ISP in ubiquinol oxidation is not available. Using the ultra-fast microfluidic mixer and the freeze-quenching device, coupled with EPR, we have been able to determine the presteady-state kinetics of ISP and cytochrome
b
L
reduction by ubiquinol. The first-phase reduction of ISP starts as early as 100 μs with a
t
1/2
of 250 μs. A similar reduction kinetic is also observed for cytochrome
b
L
, indicating a simultaneous reduction of both ISP and
b
L
. These results are consistent with the fact that no ubisemiquinone was detected at the Qp site during oxidation of ubiquinol. Under the same conditions, by using stopped flow, the reduction rates of cytochromes
b
H
and
c
1
were 403 s
−1
(
t
1/2
1.7 ms) and 164 s
−1
(
t
1/2
4.2 ms), respectively.
Altered soil microbial community at elevated CO
2
leads to loss of soil carbon
Authors: Carney Karen M. , Hungate Bruce A. , Drake Bert G. , Megonigal J. Patrick
Published: March 2007

Increased carbon storage in ecosystems due to elevated CO
2
may help stabilize atmospheric CO
2
concentrations and slow global warming. Many field studies have found that elevated CO
2
leads to higher carbon assimilation by plants, and others suggest that this can lead to higher carbon storage in soils, the largest and most stable terrestrial carbon pool. Here we show that 6 years of experimental CO
2
doubling reduced soil carbon in a scrub-oak ecosystem despite higher plant growth, offsetting ≈52% of the additional carbon that had accumulated at elevated CO
2
in aboveground and coarse root biomass. The decline in soil carbon was driven by changes in soil microbial composition and activity. Soils exposed to elevated CO
2
had higher relative abundances of fungi and higher activities of a soil carbon-degrading enzyme, which led to more rapid rates of soil organic matter degradation than soils exposed to ambient CO
2
. The isotopic composition of microbial fatty acids confirmed that elevated CO
2
increased microbial utilization of soil organic matter. These results show how elevated CO
2
, by altering soil microbial communities, can cause a potential carbon sink to become a carbon source.
On the thermodynamic stability of a charged arginine side chain in a transmembrane helix
Authors: Dorairaj Sudha , Allen Toby W.
Published: March 2007

Biological membranes consist of bilayer arrangements of lipids forming a hydrophobic core that presents a physical barrier to all polar and charged molecules. This long-held notion has recently been challenged by biological translocon-based experiments that report small apparent free energies to insert charged side chains near the center of a transmembrane (TM) helix. We have carried out fully atomistic simulations to provide the free-energy profile for moving a TM helix containing a protonated Arg side chain across a lipid bilayer. Our results reveal the fundamental thermodynamics governing the stability of charged side chains in membranes and the microscopic interactions involved. Despite local membrane deformations, where large amounts of water and lipid head groups are pulled into the bilayer to interact with Arg, the free-energy barrier is 17 kcal/mol. We provide a rationale for the differences in our microscopic free energies and cell biological experiments using free-energy calculations that indicate that a protonated Arg at the central residue of a TM helix of the Leader peptidase might reside close to the interface and not at the membrane center. Our findings have implications for the gating mechanisms of voltage-gated ion channels, suggesting that movements of protonated Arg residues through the membrane will be prohibited.
Key feature of the catalytic cycle of TNF-α converting enzyme involves communication between distal protein sites and the enzyme catalytic core
Authors: Solomon Ariel , Akabayov Barak , Frenkel Anatoly , Milla Marcos E. , Sagi Irit
Published: March 2007

Despite their key roles in many normal and pathological processes, the molecular details by which zinc-dependent proteases hydrolyze their physiological substrates remain elusive. Advanced theoretical analyses have suggested reaction models for which there is limited and controversial experimental evidence. Here we report the structure, chemistry and lifetime of transient metal–protein reaction intermediates evolving during the substrate turnover reaction of a metalloproteinase, the tumor necrosis factor-α converting enzyme (TACE). TACE controls multiple signal transduction pathways through the proteolytic release of the extracellular domain of a host of membrane-bound factors and receptors. Using stopped-flow x-ray spectroscopy methods together with transient kinetic analyses, we demonstrate that TACE's catalytic zinc ion undergoes dynamic charge transitions before substrate binding to the metal ion. This indicates previously undescribed communication pathways taking place between distal protein sites and the enzyme catalytic core. The observed charge transitions are synchronized with distinct phases in the reaction kinetics and changes in metal coordination chemistry mediated by the binding of the peptide substrate to the catalytic metal ion and product release. Here we report key local charge transitions critical for proteolysis as well as long sought evidence for the proposed reaction model of peptide hydrolysis. This study provides a general approach for gaining critical insights into the molecular basis of substrate recognition and turnover by zinc metalloproteinases that may be used for drug design.
An epigenetic mark generated by the incorporation of CENP-A into centromeric nucleosomes
Authors: Black Ben E. , Brock Melissa A. , Bédard Sabrina , Woods Virgil L. , Cleveland Don W.
Published: March 2007

Mammalian centromeres are defined epigenetically. Although the physical nature of the epigenetic mark is unknown, nucleosomes in which CENP-A replaces histone H3 are at the foundation of centromeric chromatin. Hydrogen/deuterium exchange MS is now used to show that assembly into nucleosomes imposes stringent conformational constraints, reducing solvent accessibility in almost all histone regions by >3 orders of magnitude. Despite this, nucleosomes assembled with CENP-A are substantially more conformationally rigid than those assembled with histone H3 independent of DNA template. Substitution of the CENP-A centromere targeting domain into histone H3 to convert it into a centromere-targeted histone that can functionally replace CENP-A in centromere maintenance generates the same more rigid nucleosome, as does CENP-A. Thus, the targeting information directing CENP-A deposition at the centromere produces a structurally distinct nucleosome, supporting a CENP-A-driven self-assembly mechanism that mediates maintenance of centromere identity.
Global molecular phylogeography reveals persistent Arctic circumpolar isolation in a marine planktonic protist
Authors: Darling Kate F. , Kucera Michal , Wade Christopher M.
Published: March 2007

The high-latitude planktonic foraminifera have proved to be particularly useful model organisms for the study of global patterns of vicariance and gene flow in the oceans. Such studies demonstrate that gene flow can occur over enormous distances in the pelagic marine environment leading to cosmopolitanism but also that there are ecological and geographical barriers to gene flow producing biogeographic structure. Here, we have undertaken a comprehensive global study of genetic diversity within a marine protist species, the high-latitude planktonic foraminiferan
Neogloboquadrina pachyderma
. We present extensive new data sets from the North Pacific and Arctic Oceans that, in combination with our earlier data from the North Atlantic and Southern Oceans, allow us to determine the global phylogeography of this species. The new genetic data reveal a pattern of Arctic circumpolar isolation and bipolar asymmetry between the Atlantic and Pacific Oceans. We show that the ancestry of North Pacific
N. pachyderma
is relatively recent. It lies within the upwelling systems and subpolar waters of the Southern Hemisphere and remarkably not within the neighboring Arctic Ocean. Instead, the Arctic Ocean population forms a genetic continuum with the North Atlantic population, which became isolated from the southern populations much earlier, after the onset of Northern hemisphere glaciation. Data from the planktonic foraminiferal morphospecies
Globigerina bulloides
is also introduced to highlight the isolation and endemism found within the subpolar North Pacific gyre. These data provide perspective for interpretation and discussion of global gene flow and speciation patterns in the plankton.
Self-healing of damage in fibre-reinforced polymer-matrix composites
Authors: Hayes S.A , Zhang W , Branthwaite M , Jones F.R
Published: March 2007

Self-healing resin systems have been discussed for over a decade and four different technologies had been proposed. However, little work on their application as composite matrices has been published although this was one of the stated aims of the earliest work in the field. This paper reports on the optimization of a solid-state self-healing resin system and its subsequent use as a matrix for high volume fraction glass fibre-reinforced composites. The resin system was optimized using Charpy impact testing and repeated healing, while the efficiency of healing in composites was determined by analysing the growth of delaminations following repeated impacts with or without a healing cycle. To act as a reference, a non-healing resin system was subjected to the same treatments and the results are compared with the healable system. The optimized resin system displays a healing efficiency of 65% after the first healing cycle, dropping to 35 and 30% after the second and third healing cycles, respectively. Correction for any healability due to further curing showed that approximately 50% healing efficiency could be achieved with the bisphenol A-based epoxy resin containing 7.5% of polybisphenol-A-
co
-epichlorohydrin. The composite, on the other hand, displays a healing efficiency of approximately 30%. It is therefore clear that the solid-state self-healing system is capable of healing transverse cracks and delaminations in a composite, but that more work is needed to optimize matrix healing within a composite and to develop a methodology for assessing recovery in performance.
Level set methods for the displacement of layered materials
Authors: Boon J.A , Budd C.J , Hunt G.W
Published: March 2007

Previous multi-layered folding models have struggled to describe the geometry of the interfaces between layers. In the level set method (LSM), a single function
ϕ
(
x
, 
y
, 
t
) can be used to encode all the information of a multi-layer material in which all layers are in contact and thus is a very natural way of dealing with the geometry. This paper shows the potential for the LSM (in multi-layer problems) by demonstrating that it can describe the geometry of multi-layer folding patterns including those with singularities. The method is then applied to describe the mechanics of the modelling of parallel folding in multi-layered structures.
A systematic study of hcp crystal orientation and morphology effects in polycrystal deformation and fatigue
Authors: Dunne F.P.E , Walker A , Rugg D
Published: March 2007

Elastically anisotropic, physically based, length-scale- and rate-dependent crystal plasticity finite element investigations of a model hcp polycrystal are presented and a systematic study was carried out on the effects of combinations of crystallographic orientations on local, grain-level stresses and accumulated slip in cycles containing cold dwell. It is shown that the most damaging combination is the one comprising a primary hard grain with
c
-axis near-parallel to the loading direction and an adjacent soft grain having
c
-axis near-normal to the load and a prismatic slip plane at approximately 70° to the normal to the load. We term such a combination a
rogue grain
combination. In passing, we compare results with the Stroh model and show that even under conditions of plasticity in the hcp polycrystal, the Stroh model qualitatively predicts some of the observed behaviours. It is shown that under very particular circumstances, a
morphological
–
crystallographic interaction
occurs which leads to particularly localized accumulated slip in the soft grain and the penetration of the slip into the adjacent hard grain. The interaction effect occurs only when the (morphological) orientation of the grain boundary in the rogue grain combination coincides (within approximately ±5°) with the (crystallographic) orientation of an active slip system in the soft grain. It is argued that the rogue grain combination and the morphological–crystallographic interaction are responsible for fatigue facet formation in Ti alloys with cold dwell, and a possible mechanism for facet formation is presented. The experimental observations of fatigue facet formation have been reviewed and they provide considerable support for the conclusions from the crystal plasticity modelling. In particular, faceting was found to occur at precisely those locations predicted by the model, i.e. at a rogue grain combination. Some experimental evidence for the need for a crystallographic–morphological interaction in faceting is also presented.
Colour pattern as a single trait driving speciation inHypoplectruscoral reef fishes?
Authors: Puebla Oscar , Bermingham Eldredge , Guichard Frédéric , Whiteman Elizabeth
Published: March 2007

Theory shows that speciation in the presence of gene flow occurs only under narrow conditions. One of the most favourable scenarios for speciation with gene flow is established when a single trait is both under disruptive natural selection and used to cue assortative mating. Here, we demonstrate the potential for a single trait, colour pattern, to drive incipient speciation in the genusHypoplectrus(Serranidae), coral reef fishes known for their striking colour polymorphism. We provide data demonstrating that sympatricHypoplectruscolour morphs mate assortatively and are genetically distinct. Furthermore, we identify ecological conditions conducive to disruptive selection on colour pattern by presenting behavioural evidence of aggressive mimicry, whereby predatoryHypoplectruscolour morphs mimic the colour patterns of non-predatory reef fish species to increase their success approaching and attacking prey. We propose that colour-based assortative mating, combined with disruptive selection on colour pattern, is driving speciation inHypoplectruscoral reef fishes.
Mitotic recombination counteracts the benefits of genetic segregation
Authors: Mandegar Mohammad A , Otto Sarah P
Published: March 2007

The ubiquity of sexual reproduction despite its cost has lead to an extensive body of research on the evolution and maintenance of sexual reproduction. Previous work has suggested that sexual reproduction can substantially speed up the rate of adaptation in diploid populations, because sexual populations are able to produce the fittest homozygous genotype by segregation and mating of heterozygous individuals. In contrast, asexual populations must wait for two rare mutational events, one producing a heterozygous carrier and the second converting a heterozygous to a homozygous carrier, before a beneficial mutation can become fixed. By avoiding this additional waiting time, it was shown that the benefits of segregation could overcome a twofold cost of sex. This previous result ignores mitotic recombination (MR), however. Here, we show that MR significantly hastens the spread of beneficial mutations in asexual populations. Indeed, given empirical data on MR, we find that adaptation in asexual populations proceeds as fast as that in sexual populations, especially when beneficial alleles are partially recessive. We conclude that asexual populations can gain most of the benefit of segregation through MR while avoiding the costs associated with sexual reproduction.
Introduction: some recent developments of nonlinear water wave theory
Authors: Constantin Adrian
Published: March 2007

The opening article of this issue is intended to provide a review of some relevant topics of the mathematical theory of water waves that have recently received considerable attention in the research literature. We also provide a brief discussion about the content and contribution of the articles that make up this issue.
Symmetry of steady periodic water waves with vorticity
Authors: Mikyoung Hur Vera
Published: March 2007

The symmetry and monotonicity properties of steady periodic gravity water waves are established for arbitrary vorticities if the wave profile is monotone near the trough and every streamline attains a minimum below the trough. The proof uses the method of moving planes.
On rotational water waves with surface tension
Authors: Wahlén Erik
Published: March 2007

The purpose of this paper is to present some recent advances in the study of water waves with vorticity and surface tension. These are periodic, two-dimensional waves over a flat bottom and the surface profiles are symmetric and monotone between crest and trough. The proofs rely on bifurcation theory.
Rotational steady water waves near stagnation
Authors: Constantin Adrian , Strauss Walter
Published: March 2007

We investigate the location of the point of maximal horizontal velocity for steady periodic water waves with vorticity.
Particle trajectories in linear periodic capillary and capillary–gravity water waves
Authors: Henry David
Published: March 2007

Surface tension plays a significant role as a restoration force in the setting of small-amplitude waves, leading to pure capillary and gravity-capillary waves. We show that within the framework of linear theory, the particle paths in a periodic gravity–capillary or pure capillary wave propagating at the surface of water over a flat bed are not closed.
The string density problem and the Camassa–Holm equation
Authors: Beals Richard , Sattinger David H , Szmigielski Jacek
Published: March 2007

Recently, the string density problem, considered in the pioneering work of M. G. Krein, has arisen naturally in connection with the Camassa–Holm equation for shallow water waves. In this paper we review the forward and inverse string density problems, with some numerical examples, and relate it to the Camassa–Holm equation, with special reference to multi-peakon/anti-peakon solutions. Under stronger assumptions, the Camassa–Holm spectral problem and the string density problem can be transformed to the Schrödinger spectral problem and its inverse problem. Recent results exploiting this transformation are reviewed briefly.
Rice functional genomics research in China
Authors: Han Bin , Xue Yongbiao , Li Jiayang , Deng Xing-Wang , Zhang Qifa
Published: March 2007

Rice functional genomics is a scientific approach that seeks to identify and define the function of rice genes, and uncover when and how genes work together to produce phenotypic traits. Rapid progress in rice genome sequencing has facilitated research in rice functional genomics in China. The Ministry of Science and Technology of China has funded two major rice functional genomics research programmes for building up the infrastructures of the functional genomics study such as developing rice functional genomics tools and resources. The programmes were also aimed at cloning and functional analyses of a number of genes controlling important agronomic traits from rice. National and international collaborations on rice functional genomics study are accelerating rice gene discovery and application.
Quorum sensing, virulence and secondary metabolite production in plant soft-rotting bacteria
Authors: Barnard Anne M.L , Bowden Steven D , Burr Tom , Coulthurst Sarah J , Monson Rita E , Salmond George P.C
Published: March 2007

Quorum sensing describes the ability of bacteria to sense their population density and respond by modulating gene expression. In the plant soft-rotting bacteria, such as
Erwinia
, an arsenal of plant cell wall-degrading enzymes is produced in a cell density-dependent manner, which causes maceration of plant tissue. However, quorum sensing is central not only to controlling the production of such destructive enzymes, but also to the control of a number of other virulence determinants and secondary metabolites.
Erwinia
synthesizes both
N
-acylhomoserine lactone (AHL) and autoinducer-2 types of quorum sensing signal, which both play a role in regulating gene expression in the phytopathogen. We review the models for AHL-based regulation of carbapenem antibiotic production in
Erwinia
. We also discuss the importance of quorum sensing in the production and secretion of virulence determinants by
Erwinia
, and its interplay with other regulatory systems.
Quorum-sensing blockade as a strategy for enhancing host defences against bacterial pathogens
Authors: Bjarnsholt Thomas , Givskov Michael
Published: March 2007

Conventional antibiotics target the growth and the basal life processes of bacteria leading to growth arrest and cell death. The selective force that is inherently linked to this mode of action eventually selects out antibiotic-resistant variants. The most obvious alternative to antibiotic-mediated killing or growth inhibition would be to attenuate the bacteria with respect to pathogenicity. The realization thatPseudomonas aeruginosa, and a number of other pathogens, controls much of their virulence arsenal by means of extracellular signal molecules in a process denoted quorum sensing (QS) gave rise to a new ‘drug target rush’. Recently, QS has been shown to be involved in the development of tolerance to various antimicrobial treatments and immune modulation. The regulation of virulence via QS confers a strategic advantage over host defences. Consequently, a drug capable of blocking QS is likely to increase the susceptibility of the infecting organism to host defences and its clearance from the host. The use of QS signal blockers to attenuate bacterial pathogenicity, rather than bacterial growth, is therefore highly attractive, particularly with respect to the emergence of multi-antibiotic resistant bacteria.
Cross-kingdom signalling: exploitation of bacterial quorum sensing molecules by the green seaweed
Ulva
Authors: Joint Ian , Tait Karen , Wheeler Glen
Published: March 2007

The green seaweed
Ulva
has been shown to detect signal molecules produced by bacteria. Biofilms that release
N
-acylhomoserine lactones (AHLs) attract zoospores—the motile reproductive stages of
Ulva
. The evidence for AHL involvement is based on several independent lines of evidence, including the observation that zoospores are attracted to wild-type bacteria that produce AHLs but are not attracted to mutants that do not produce signal molecules. Synthetic AHL also attracts zoospores and the attraction is lost in the presence of autoinducer inactivation (AiiA) protein. The mechanism of attraction is not chemotactic but involves chemokinesis. When zoospores detect AHLs, the swimming rate is reduced and this results in accumulation of cells at the source of the AHL. It has been demonstrated that the detection of AHLs results in calcium influx into the zoospore. This is the first example of a calcium signalling event in a eukaryote in response to bacterial quorum sensing molecules. The role of AHLs in the ecology of
Ulva
is discussed. It is probable that AHLs act as cues for the settlement of zoospores, rather than being directly involved as a signalling mechanism.
Acylated homoserine lactones in the environment: chameleons of bioactivity
Authors: Manefield Mike , Whiteley Andrew S
Published: March 2007

Over the last 15 years, it has become increasingly apparent that a single class of compounds, the acylated homoserine lactones (AHLs), elicit effects on many levels of biological and ecological organization. Despite the fact that the distribution of AHL production in the prokaryotic phylogenetic tree is restricted to a small set of genera, representatives of these genera are abundant in the environment and are responsible for processes of much interest to humans. As well as driving interactions between clones, AHLs have been shown to mediate interactions between different species of bacteria and between bacteria and higher organisms, either through the phenotypes they regulate or directly through their own chemical behaviour. Understanding the biological activity of AHLs and the ecological consequences of these activities may provide us with an opportunity to manipulate the composition and function of complex biological assemblages. Ultimately, this broadens the biotechnological focus of AHL-based research beyond the attenuation of virulence in humans and plant pathogens.
An autonomous self contained wall climbing robot for non‐destructive inspection of above‐ground storage tanks
Authors: Kalra Love P. , Gu Jason
Published: March 2007

Purpose

The aim of this research is to design a wall climbing robot (WCR) for the non‐destructive inspection (NDT) of the above‐ground storage tanks (ASTs) autonomously making the industrial inspection and maintenance tasks safer.

Design/methodology/approach

A WCR is designed that can be equipped with any NDT sensor. It uses permanent magnets as an adhesion mechanism to crawl over the steel tank walls. A surface coverage algorithm is proposed for the WCR to scan the AST wall surfaces autonomously with the NDT sensors to perform the necessary inspection tasks.

Findings

The proposed surface coverage algorithm performs the complete coverage of the AST walls under different obstacle configurations. It has been tested and demonstrated in simulations.

Originality/value

A surface coverage algorithm is proposed for the WCR to perform the non‐destructive inspection of the ASTs autonomously. It can also be used in applications like cleaning glass building and painting ship hulls, etc.
Fibroblast growth factor‐2‐induced host stroma reaction during initial tumor growth promotes progression of mouse melanoma via vascular endothelial growth factor A‐dependent neovascularization
Authors: Tsunoda Satoshi , Nakamura Toshiyuki , Sakurai Hiroaki , Saiki Ikuo
Published: March 2007

Fibroblast growth factor (FGF)‐2 has been considered to play a critical role in neovascularization in several tumors; however, its precise role in tumor progression is not fully understood. In the present study, we have characterized the role of FGF‐2 in B16‐BL6 mouse melanoma cells, focusing on effects during the initial phase of tumor growth. FGF‐2 was injected at the tumor inoculation site of dorsal skin during the initial phase. FGF‐2 induced marked tumor growth and lymph node metastasis. This was well correlated with an increase in neovascularization in the host stroma. FGF‐2 also recruited inflammatory and mesenchymal cells in host stroma. Marked tumor growth, pulmonary metastasis and intensive neovascularization in tumor parenchyma were also observed after a single injection of FGF‐2 into the footpad inoculation site. In contrast, repeated injections of FGF‐2 at a site remote from the footpad tumor were ineffective in promoting tumor growth and metastasis. These promoting activities of FGF‐2 were blocked by local injections of a glucocorticoid hormone, suggesting that host inflammatory responses induced by FGF‐2 are associated with FGF‐2‐induced tumor progression. In addition, although FGF‐2 did not promote cellular proliferation and vascular endothelial growth factor A (VEGFA) mRNA expression in B16‐BL6 cells in vitro, FGF‐2 induced VEGFA expression in host stroma rather than tumor tissue, and local injections of a neutralizing antibody against VEGFA inhibited these activities of FGF‐2 in vivo. These results indicate that abundant FGF‐2 during the initial phase of tumor growth induces VEGFA‐dependent intensive neovascularization in host stroma, and supports marked tumor growth and metastasis. (Cancer Sci 2007; 98: 541–548)
TACC3 is required for the proper mitosis of sclerotome mesenchymal cells during formation of the axial skeleton
Authors: Yao Ryoji , Natsume Yasuko , Noda Tetsuo
Published: March 2007

Transforming acidic coiled‐coil‐containing (TACC) family members regulate mitotic spindles and have essential roles in embryogenesis. However, the functions of TACC3 in mitosis during mammalian development are not known. We have generated and characterized three mutant alleles of mouseTacc3including a conditional allele. Homozygous mutants of a hypomorphic allele exhibited malformations of the axial skeleton. The primary cause of this defect was the failure of mitosis in mesenchymal sclerotome cells.In vitro, 36% of primary mouse embryo fibroblasts (MEF) obtained from mutants homozygous for the hypomorphic allele and 67% of MEF fromTacc3null mutants failed mitosis. In cloned immortalized MEF, Tacc3 depletion destabilized spindles and prevented chromosomes from aligning properly. Furthermore, chromosome separation and cytokinesis were also severely impaired. Chromosomes were moved randomly and cytokinesis initiated but the cleavage furrow eventually regressed, resulting in binucleate cells that then yielded aneuploid cells in the next cell division. Thus, in addition to spindle assembly, Tacc3 has critical roles in chromosome separation and cytokinesis, and is essential for the mitosis of sclerotome mesenchymal cells during axial formation in mammals. (Cancer Sci2007; 98: 555–562)
Establishment of the enzyme‐linked immunosorbent assay system to detect the amino terminal secretory form of rat Erc/Mesothelin
Authors: Nakaishi Masayuki , Kajino Kazunori , Ikesue Masahiro , Hagiwara Yoshiaki , Kuwahara Maki , Mitani Hiroaki , Horikoshi‐Sakuraba Yuko , Segawa Tatsuya , Kon Shigeyuki , Maeda Masahiro , Wang Tegexibaiyin , Abe Masaaki , Yokoyama Masayoshi , Hino Okio
Published: March 2007

By representational difference analysis, we previously identified the rat Erc (Expressed in renal carcinoma) gene that was more abundantly expressed in the renal carcinoma tissues of Eker rats than in the rat normal kidney. In this study, we raised antibodies against the amino‐terminal portion of the rat Erc, and demonstrated the existence of a ∼30‐kDa secretory form in the supernatant of cultured cells derived from rat renal carcinoma. The enzyme‐linked immunosorbent assay (ELISA) system using these antibodies detected high concentrations of this form in the sera of Eker rats bearing renal carcinomas, and in the sera of rats transplanted with mesothelioma cells. Mesothelin, a human homolog of the rat Erc, was recently reported to be a serum marker of malignant mesothelioma. The prognosis of mesothelioma is poor and there is no effective treatment at present. There are several rat model systems of mesothelioma that may be promising tools in the development of an antimesothelioma treatment. We hope our ELISA to detect the soluble form of rat Erc/Mesothelin is useful in the rat model system to exploit the antimesothelioma therapy to be used in human cases. (Cancer Sci 2007; 98: 659–664)
Photodynamic therapy‐generated tumor cell lysates with CpG‐oligodeoxynucleotide enhance immunotherapy efficacy in human papillomavirus 16 (E6/E7) immortalized tumor cells
Authors: Bae Su‐Mi , Kim Yong‐Wan , Kwak Sun‐Young , Kim Yong‐Wook , Ro Duck‐Yeong , Shin Jong‐Chul , Park Choong‐Hak , Han Sei‐Jun , Oh Chung‐Hun , Kim Chong‐Kook , Ahn Woong‐Shick
Published: March 2007

Immunotherapy with photodynamic therapy (PDT) offers great promise as a new alternative for cancer treatment; however, its use remains experimental. In this study, we examined the immunotherapeutic significance of human papillomavirus (HPV)‐immortalized tumor cell lysates induced by PDT with CpG‐oligodeoxynucleotide (ODN). PDT‐cell lysates were generated by irradiating Radachlorin (5 µg/mL) preloaded TC‐1 cells carrying HPV 16 E7. PDT‐cell lysates plus ODN coinjection for protection against E7‐expressing tumors as well as specific immune responses were evaluated with the following tests: heat shock protein 70 (HSP70) enzyme‐linked immunosorbent assay, in vitro and in vivo tumor growth inhibition, interferon‐γ (IFN‐γ) and tumor necrosis factor‐α (TNF‐α) assay, cytotoxic T‐lymphocyte assay, and fluorescence activated cell sorting (FACS) analysis. PDT‐cell lysates plus ODN coinjection showed a significant suppression of tumor growth at both prophylactic and therapeutic levels, compared to PDT (or F/T)‐cell lysates or ODN alone. In addition, we evaluated the level of the immune response with the coinjection. HSP70, an important regulator of inflammatory and immune response, was observed in abundance in the PDT‐cell lysates. IFN‐γ production and cytotoxic T lymphocytes (CTL) responses were induced by PDT‐cell lysates plus ODN injection. The coinjection resulted in PDT‐cell lysate‐specific antibodies (IgG1, IgG2a, IgG2b, and IgG3) and T‐helper cell responses significantly higher than PDT‐cell lysates alone. Moreover, IFN‐γ production and CTL responses were significantly induced in the PDT‐cell lysate plus ODN immunized groups. These enhanced immune responses appeared to be mediated by CD8+ T cells only. These data suggest that PDT‐cell lysates plus ODN injection may be an effective approach to induce CTL immune responses as a possible immunotherapeutic strategy for cancer therapy. (Cancer Sci 2007; 98: 747–752)
In vivo and in silico studies on single versus multiple transplants for multiple myeloma
Authors: Dingli David , Pacheco Jorge M. , Dispenzieri Angela , Hayman Suzanne R. , Kumar Shaji K. , Lacy Martha Q. , Gastineau Dennis A. , Gertz Morie A.
Published: March 2007

High‐dose therapy and autologous stem cell transplantation (HDT‐ASCT) have significantly improved survival in multiple myeloma (MM). However, patients are not cured, responses are variable and only about 40% of patients achieve a complete response (CR). Optimal timing of the procedure and knowledge of the relapse kinetics may assist physicians when they consider this therapeutic modality for their patients. We analyzed myeloma tumor burden and kinetics before and after HDT‐ASCT in a cohort of 265 patients. Disease burden was estimated from serial M‐spike measurements and the data fitted to the Gompertz function to determine the general parameters for all patients. Functions that couple disease burden and kinetics with time to progression (TTP) were derived and used to determine the optimal timing of transplantation. Patients who achieve CR with the first episode of HDT‐ASCT should not be routinely offered tandem transplantation but carefully monitored and transplanted at an optimal disease burden. If CR is not achieved with a first trial of HDT‐ASCT, the probability of CR after a tandem second trial is ∼10%. TTP after tandem transplants (with its higher associated mortality) cannot be superior to TTP achieved with optimally timed serial transplants. Individualized HDT‐ASCT for patients with MM is possible and may optimize results. (Cancer Sci 2007; 98: 734–739)
Natural killer T cells from interleukin‐4‐deficient mice are defective in early interferon‐γ production in response to α‐galactosylceramide
Authors: Togashi Yuji , Chamoto Kenji , Wakita Daiko , Tsutsumi Naonobu , Iwakura Yoichiro , Matsubara Naoki , Kitamura Hidemitsu , Nishimura Takashi
Published: March 2007

Discovery of the natural killer (NK) T cell‐specific ligand, α‐galactosylceramide (α‐GalCer) has enabled us to investigate the functional regulation of NKT cells. However, the detailed mechanism of cytokine production by NKT cells remains to be elucidated. Here we evaluated the role of interleukin (IL)‐4 in the production of interferon (IFN)‐γ from NKT cells using IL‐4‐deficient C57BL/6 mice (IL‐4−/– mice). Administration of α‐GalCer into wild‐type C57BL/6 mice caused the production of both IFN‐γ and IL‐4 in serum or cytoplasm within 4 h of the injection. Unexpectedly, however, IL‐4−/– mice‐derived NKT cells did not produce any IFN‐γ at early phase after primary stimulation with α‐GalCer. Because NKT cells from IL‐4−/– mice produced IFN‐γ when they were stimulated secondarily with α‐GalCer in vitro for 72 h, NKT cells from IL‐4−/– mice were not completely genetically deficient for IFN‐γ production. To elucidate which cells, NKT cells or dendritic cells (DC), were responsible for the deficiency in IFN‐γ production in IL‐4−/– mice, we carried out an add‐back experiment using purified NKT cells and DC, which were prepared from either wild‐type mice or IL‐4−/– mice. NKT cells from wild‐type mice produced IFN‐γ when they were cocultured with DC prepared from either wild‐type or IL‐4−/– mice, whereas NKT cells from IL‐4−/– mice did not produce IFN‐γ by coculturing with DC from either wild‐type or IL‐4−/– mice. These results indicate that NKT cells, not DC, were responsible for the deficiency in IFN‐γ production in IL‐4−/– mice. Thus, IL‐4 is required for the activation of NKT cells to produce IFN‐γ in response to α‐GalCer. (Cancer Sci 2007; 98: 721–725)
Performance of six types of oxygen delivery devices at varying respiratory rates*
Authors: Wagstaff T. A. J. , Soni N.
Published: March 2007

The administration of a known concentration of oxygen is an important part of routine care of the sick patient. Many devices are currently available. The actual concentration of oxygen that can be delivered by these devices can be affected by several factors, both from the patient as well as the device itself. Measuring the Fio2 delivered to the lungs in vivo can be both difficult and potentially uncomfortable for the subjects. We constructed a model using a resuscitation manikin, a ventilator and a set of bellows to simulate ventilation. With this model we tested a series of devices – variable performance, fixed performance and high flow – at two fixed tidal volumes. The respiratory rate was increased and its effect on the oxygen concentration assessed. Variable performance systems such as the Hudson mask deliver a significantly reduced oxygen concentration at high respiratory rates. Fixed performance systems delivering 24–40% oxygen deliver appropriate oxygen concentrations across the range of respiratory rates, whereas those delivering 60% show a reduction in performance. High flow systems show no failure of performance at increased respiratory rates.
Acute MDMA and ethanol interaction effects on psychomotor performance
Authors: Dumont G. J. H. , Valkenberg M. M. G. J. , Schoemaker R. , Buitelaar J. K. , Van Gerven J. M. A. , Verkes R. J.
Published: March 2007

Introduction:  A considerable percentage of young people expose themselves to 3,4‐methylenedioxy‐methamphetamine (MDMA or ‘ecstasy’). Alcohol is relatively commonly used in combination with MDMA (Barrett et al., 2005). As a percentage of MDMA users admit to driving under influence (Riley et al., 2001), the assessment of the effects of co‐administration of these substances on psychomotor performance is warranted.

Hypothesis:  We hypothesized that the co‐administration of MDMA and ethanol would ameliorate the impairment induced by ethanol alone.

Methods:  We performed a double‐blind, randomized, placebo‐ controlled study in 16 healthy volunteers (9 male, 7 female) in the age of 18–29 years. MDMA 100 mg was given orally and blood alcohol concentration (BAC) was maintained at 0.6‰ by a three hour 10% alcohol infusion regime (adjustment of infusion rate according to regular sampled breath alcohol concentration). Saccadic and smooth pursuit eye movements, a validated measure of ethanol induced sedation (van Steveninck et al., 1999), were recorded using Nihon Kohden® and Cambridge Electronic Design (CED®) hardware and Spike2® software at 1 : 35 post drug administration. Results were statistically evaluated using GLM in SPSS® 11.5.

Results:  Results are presented in table 1. Saccadic peak velocity was increased after MDMA (p=0.000). Co‐administration showed significant increase in peak saccadic velocity compared to placebo (p=0.004), although significantly less then the increase as observed after MDMA alone (p=0.003). Smooth pursuit was significantly impaired after ethanol compared to placebo (p=0.000) and MDMA (p=0.000), co‐adminstration also impaired score compared to placebo (p=0.000) and MDMA (p=0.000).

  Eye movement scores per drug

Eye movements
Placebo
Ethanol
MDMA
Ethanol + MDMA

Mean
SD
Mean
SD
Mean
SD
Mean
SD

Peak saccadic

◆, ♠

*, •, ♠

*, •, ◆

velocity (deg/s)
458,1
66,1
452,8
54,8
543,5
76,3
497,2
65,8

Saccadic reaction time (ms)
190,8
25,3
194,4
26,1
193,0
24,9
191,6
24,9

Average smooth

*, ◆

•, ♠

*, ◆

pursuit (%)
49,08
12,00
37,56
9,72
52,74
14,30
38,90
9,85

*=Significant vs. placebo, • =Significant vs. ethanol, ◆=Significant vs. MDMA, ♠ = Significant vs. MDMA + ethanol.

Conclusions:  MDMA induced arousal as measured by the saccadic peak velocity when administered alone and, to a lesser degree, in combination with ethanol. Co‐administration of MDMA with ethanol however could not ameliorate the deterioration of psychomotor accuracy by ethanol as measured by smooth pursuit eye movements. These findings suggest that although MDMA might ameliorate ethanol induced sedation it does not ameliorate impaired psychomotor skills. This might give a false sense of improved performance while intoxicated and thus increases risks of for example road accidents.