bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Polarizabilities, Polarizability Anisotropies and Order Parameters of Nematic Liquid Crystals
Authors: Murthy Y. Narasimha , Murthy V. R.
Published: January 2007

Mean Molecular polarizabilities, polarizability anisotropies and order parameters are evaluated in members of three homologous series, using two theoretical models. The variation of polarizabilities and their anisotropies with number of carbon atoms in the alkyl chain is studied. The temperature dependence of order parameter is also presented. The results are compared with the reported values and the merits of the different models are discussed.
The Effect of Fluoride Concentration and Catalyst Preparation Method on Structural and Thermal Properties of CoMo/Al2O3 Catalysts
Authors: Sarbak Z.
Published: January 2007

The effect of the sequence of incorporation of F− ions on the properties of fluorinated CoMo/Al2O3 catalysts was investigated by the methods of X‐ray diffraction, infrared spectroscopy and thermal analysis. Three kinds of samples were prepared into which the F− ions were introduced either simultaneously with Co and Mo (sample labelled as CoMoF), or prior to them (F/CoMo) or after them (CoMo/F). The samples contained fixed amounts of Mo (15 wt.% MqO3) and Co (3 wt.% CoO). Formation of surface di‐ and polymolybdate species as well as Al–F was evidenced in all samples. The concentration of molybdenum containing species was the highest in CoMoF sample, while that of fluoride containing species was the highest in CoMo/F samples.
Crystal Structure of 4‐Phenyl‐5‐(2,3,4‐trimetoxyphenyl)‐isoxazole
Authors: Sanmartin R. , Olivera R. , Domínguez E. , Solans X. , Font‐bardia M. , Urtiaga M. K.
Published: January 2007

The X‐ray crystal structure of 4‐phenyl‐5‐(2,3,4‐trimethoxyphenyl)‐isoxole, C18H17NO4, (I) has been determined, revealing an interesting lack of coplanarity for the aromatic rings system. This preferred conformation implies reduction of the conjugation degree, as shown by the C(2)‐C(10) and C(3)‐C(4) bond‐length values. The arrangement of the three methoxy substituents is also examined.
Compensation Mechanism in Vanadium and Gallium Doped CdTe and (Cd,Zn)Te
Authors: Joerger W. , Laasch M. , Kunz T. , Fiederle M. , Meinhardt J. , Benz K. W. , Scholz K. , Wendl W. , Müller‐vogt G.
Published: January 2007

Vanadium and gallium doped CdTe crystals were grown from the vapour phase (modified Markov method) and (Cd0.9Zn0.1)Te: V from the melt (vertical Bridgman). The crystals were characterized by photoinduced current transient spectroscopy (PICTS), photoluminescence (PL) and time dependent charge measurements (TDCM). Transitions from different charge states (V2+/V3+) of the vanadium donor have been observed in the V‐doped crystals by PICTS. A shallow donor level (dE = 0.068 eV) and the Ga A‐center have been identified by PICTS and PL measurements in CdTe:Ga. In case of V‐doping high resistivity is achieved all over the crystal while Ga‐doping results in a high resistivity region only in the middle of the crystal. Calculation of the resistivity by means of a compensation model shows that for both dopants an additional not observed deep donor has to be assumed in order to describe the resistivity distributions.
Growth of Bi–Sb Gradient Crystals for X‐ray Monochromators by means of the Gradient Projection Method
Authors: Penzel St. , Kleessen H. , Neumann W.
Published: January 2007

Crystals with a well defined slope of composition have been grown by the Gradient Projection Method (GPM). In the system Bi–Sb gradient crystals with a lattice parameter gradient of Δa/Δa/dz = 0.835%/cm and Δc/c/dz = 0.79%/cm have been obtained. The concentration profiles of the grown crystals with large single crystalline parts exhibit a linear distribution.

The adjustment of the dissolving rate allows to control the growth velocity and thus the quality of the grown crystals is increased.
Liquid Phase Epitaxy (LPE) of YB2Cu3O7‐δ High Tc Superconductors
Authors: Aichele T. , Bornmann S. , Dubs C. , Görnert P.
Published: January 2007

YBa2Cu3O7‐δ films were grown by liquid phase epitaxy in Y‐ZrO2 crucibles on (110)NdGaO3 substrates. A change in the preferred crystallographic growth direction was observed reproducibly. The growth mode changes from pure c‐axis oriented over mixed c/a‐axis oriented films to pure a‐axis oriented films with increasing undercooling. X‐ray diffraction measurements and atomic force microscopy investigations with c‐axis oriented as well as a‐axis oriented films are presented. It will be shown that atomically smooth steps with 0.2‐0.8 μM width can be achieved by LPE, which are free from melt remnants. Furthermore the values for the enthalpy of dissolution from literature, which are varying in a wide range, will be combined and a new value will be calculated in terms of a multi particle model.
Single‐fiber electromyography during menstrual exacerbation and ovulatory suppression in MuSK antibody–positive myasthenia gravis
Authors: Stickler David E. , Stickler Laura L.
Published: January 2007

We report a patient with muscle‐specific tyrosine kinase (MuSK) antibody–positive myasthenia gravis who experienced worsening of myasthenic weakness associated with alterations in estrogen and progesterone levels during the administration of oral contraceptive therapy. Single‐fiber electromyography was performed to document changes in neuromuscular transmission associated with the clinical exacerbation and subsequent resolution of the menstrual exacerbation and clinical improvement experienced with continuous monophasic oral contraceptive therapy. The potential long‐term benefit of ovulatory suppression in MuSK antibody–positive myasthenia gravis is discussed. Muscle Nerve, 2007
Eosinophilic fibrosing gastritis and toxoplasmosis in a cat
Authors: McConnell James F. , Sparkes Andrew H. , Blunden Anthony S. , Neath Prue J. , Sansom Jane
Published: January 2007

A 3-year-old, neutered male Tiffany cat was presented to the Animal Health Trust for investigation of pyrexia and a gastric lesion. Radiography and ultrasound showed severe thickening of the gastric wall and regional lymphadenopathy. There was altered gastric wall layering, predominately due to muscularis thickening. Histopathology confirmed eosinophilic fibrosing gastritis. The cat also had evidence of generalised Toxoplasma gondii infection, which may have been responsible for the gastric changes.
Triggering at the Distal A2 Pulley
Authors: NAGAOKA M. , YAMAGUCHI T. , NAGAO S.
Published: January 2007

We report two cases with triggering at the distal end of the A2 pulley. One was caused by enlargement of the flexor digitorum profundus (FDP) tendon and the other by enlargement of both slips of the flexor digitorum superficialis (FDS) tendon. Both were relieved by reduction tenoplasty and short releases, or venting, of the distal A2 pulley.
Single‐Step Purification of Recombinant Thermus aquaticus DNA Polymerase Using DNA‐Aptamer Immobilized Novel Affinity Magnetic Beads
Authors: Oktem Huseyin Avni , Bayramoglu Gulay , Ozalp V. Cengiz , Arica M. Yakup
Published: January 2007

A DNA aptamer specific for Thermus aquaticus DNA polymerase (Taq‐polymerase) was immobilized on magnetic beads, which were prepared in the presented study. The effect of various parameters including pH, temperaturem and aptamer concentration on the immobilization of 5′‐thiol labeled DNA‐aptamer onto glutaric dialdhyde activated magnetic beads was evaluated. The binding conditions of Taq‐polymerase on the aptamer immobilized magnetic beads were studied using commercial Taq‐polymerase to characterize the surface complexation reaction. Efficiency of affinity magnetic beads in the purification of recombinant Taq‐polymerase from crude extracts was also evaluated. For this case, the enzyme “recombinant Taq‐DNA polymerase” was cloned and expressed using an Amersham E. coli GST‐Gene Fusion Expression system. Crude extracts were in contact with affinity magnetic beads for 30 min and were collected by magnetic field application. The purity of the eluted Tag‐polymerase from the affinity beads, as determined by HPLC, was 93% with a recovery of 89% in a one‐step purification protocol. Apparently, the system was found highly effective as one step for the low‐cost purification of Taq‐polymerase in bacterial crude extract.
Target Control of Cell Disruption To Minimize the Biomass Electrostatic Adhesion during Anion‐Exchange Expanded Bed Adsorption
Authors: Lin Dong‐Qiang , Dong Jian‐Nan , Yao Shan‐Jing
Published: January 2007

Expanded bed adsorption (EBA) is an integrative unit operation for the primary recovery of bioproducts from crude feedstock. Biomass electrostatic adhesion often leads to bad bed stability and low adsorption capacity. The results indicate that effective cell disruption is a potential approach to reduce the biomass adhesion during anion‐exchange EBA. Two common cell disruption methods (sonication treatment and high‐pressure disruption with a French press) were investigated in the present work. The mean size of cell debris reduced dramatically during the cell disruption process, and the absolute value of the ζ potential of cell debris also decreased significantly as the mean size reduced. The biomass transmission index (BTI) obtained through the biomass pulse response experiment was used to quantitatively evaluate the biomass‐adsorbent interaction. Combining the influences of ζ potential of adsorbent (ζA), ζ potential of biomass (ζB), and biomass mean size ( dB), the parameter of (–ζA·ζB· dB) was explored as a reasonable indicator of biomass adhesion in expanded beds. A good linear correlation was confirmed between BTI and (–ζA·ζB· dB) for all biomass and cell disruption conditions tested, which was independent of the cell disruption methods. A target parameter (–ζA·ζB· dB) of 120 mV2μm was derived for BTI above 0.9, which meant a very slight influence of biomass on the stability of the expanded bed. This criterion could be used as a rational control target for cell disruption processes in EBA applications.
Tropical sea surface temperature, vertical wind shear, and hurricane development
Authors: Latif M. , Keenlyside N. , Bader J.
Published: January 2007

The anomalously strong hurricane activity in the Atlantic sector during the recent years led to a controversy about the impact of global warming on hurricane activity in the Atlantic sector. Here we show that the temperature difference between the tropical North Atlantic and the tropical Indian and Pacific Oceans (Indo‐Pacific) is a key parameter in controlling the vertical wind shear over the Atlantic, an important quantity for hurricane activity. The stronger warming of the tropical North Atlantic relative to that of the Indo‐Pacific during the most recent years drove reduced vertical wind shear over the Atlantic and is thus responsible for the strong hurricane activity observed. In 2006, however, the temperature difference between the tropical North Atlantic and the tropical Indian and Pacific Oceans is much reduced, which explains the relatively weak hurricane season.
Coseismic and postseismic creep in the Andaman Islands associated with the 2004 Sumatra‐Andaman earthquake
Authors: Kayanne Hajime , Ikeda Yasutaka , Echigo Tomoo , Shishikura Masanobu , Kamataki Takanobu , Satake Kenji , Malik Javed N. , Basir Shaikh R. , Chakrabortty Gautam K. , Roy Ashish K. Ghosh
Published: January 2007

Two field campaigns (March 2005 and March 2006) for measurements of biological indicators and eyewitness accounts confirm that large coseismic and postseismic surface deformation occurred over the Andaman Islands in association with the 2004 Sumatra‐Andaman earthquake. Amount of uplift was as large as 1.3 m in the islands off NW coast, and decreased to ESE with a zone of subsidence in the SE Andaman. The coseismic deformation did not generate large seismic waves or tsunamis, indicating that slip was much slower than that off Sumatra. The coseismic uplift was followed by postseismic subsidence, which was evidenced by local residents to have occurred within two months after the earthquake. A simple dislocation model explains the deformation pattern by a coseismic rupture (50 km wide with its down‐dip limit 130 km east of the trench axis) followed by an up‐dip propagation of the rupture front for about 10 km.
Generalized spheroidal wave equation and limiting cases
Authors: Figueiredo B. D. Bonorino
Published: January 2007

We find sets of solutions to the generalized spheroidal wave equation (GSWE) or, equivalently, to the confluent Heun equation. Each set is constituted by three solutions, one given by a series of ascending powers of the independent variable, and the others by series of regular and irregular confluent hypergeometric functions. For a fixed set, the solutions converge over different regions of the complex plane but present series coefficients proportional to each other. These solutions for the GSWE afford solutions to a double-confluent Heun equation by a taking-limit process due to Leaver. [E. W. Leaver, J. Math. Phys. 27, 1238 (1986)]. Another procedure, called Whittaker-Ince limit [B. D. Figueiredo, J. Math. Phys. 46, 113503 (2005)], provides solutions in series of powers and Bessel functions for two other equations with a different type of singularity at infinity. In addition, new solutions are obtained for the Whittaker-Hill and Mathieu equations [F. M. Arscott, Proc. R. Soc. Edinburg A67, 265 (1967)] by considering these as special cases of both the confluent and double-confluent Heun equations. In particular, we find that each of the Lindemann-Stieltjes solutions for the Mathieu equation [E. T. Whittaker and G. N. Watson, A Course of Modern Analysis, Cambridge University Press (1945)] is associated with two expansions in series of Bessel functions. We also discuss a set of solutions in series of hypergeometric and confluent hypergeometric functions for the GSWE and use their Leaver limits to obtain infinite-series solutions for the Schrödinger equation with an asymmetric double-Morse potential. Finally, the possibility of extending the solutions of the GSWE to the general Heun equation is briefly discussed.
Influence of vibrations on thermodiffusion in binary mixture: A benchmark of numerical solutions
Authors: Shevtsova V. , Melnikov D. , Legros J. C. , Yan Y. , Saghir Z. , Lyubimova T. , Sedelnikov G. , Roux B.
Published: January 2007

Double-diffusive and vibrational convection with the Soret effect is considered in a cubic rigid cell filled with water (90%) and isopropanol (10%), subjected to a temperature difference between opposite lateral walls. Numerical simulations are carried out for g-jitter induced flow. The direction of g-jitter is the same as the residual gravity vector, which is perpendicular to the applied temperature gradient. Along with various combinations of static and oscillatory components, vibrations with two different frequencies are examined: (a) when the period of oscillations is smaller than any characteristic time (viscous, thermal, and diffusion), f=0.2Hz; (b) when the period of oscillations is comparable with viscous time, f=0.01Hz. Component separation due to the Soret effect under these driving actions is analyzed. The concept of time-averaged models is applied for the explanation of the high-frequency results. The interplay between the mean and fluctuating motions is discussed. Three research groups performed a benchmark of numerical solutions of three-dimensional Navier-Stokes, energy, and concentration equations using the true physical parameters for a future Space experiment. The objective of this paper is twofold: (i) to carry out an accurate study of heat and mass transfer in a binary liquid with the Soret effect in the presence of steady residual gravity and its oscillatory component; (ii) to carry out a benchmark of numerical solutions.
Relationship between airflow at the critical height and momentum transfer to the traveling waves
Authors: Kihara N. , Hanazaki H. , Mizuya T. , Ueda H.
Published: January 2007

Direct numerical simulations of the airflow over periodic traveling waves were performed to investigate the applicability of two mechanisms related to momentum transfer from the turbulent airflow to the traveling waves, i.e., the critical-layer mechanism and the nonseparated sheltering. We found three regimes classified by the wave age. In the first regime at low wave ages (2⩽c∕u*⩽4), the critical height is located in the thin inner region where nonseparated sheltering works, and the perturbations of the shear stress in the inner region directly affect the streamwise phase of pressure on the wave surface. In the second regime at intermediate wave ages (4<c∕u*⩽12), the critical layer is located in the thick inner region and has a strong link to momentum transfer across the interfacial wave. In particular, the phase of wave-induced pressure on the wave surface  ∣ϕp̃∣bot is determined by the phase of wave-induced vertical velocity at the critical height  ∣ϕw̃∣z=zc as  ∣ϕp̃∣bot≈∣ϕw̃∣z=zc+π∕2. In this regime, the growth rate of the interfacial wave is predicted well by the critical-layer mechanism. In the third regime at high wave ages (c∕u*⩾16), the critical height is in the outer region far above the inner region, and the assumption of the critical-layer mechanism is better satisfied. However, momentum transfer across the interface in this regime is determined mainly by the local flow in the inner region and it is only weakly affected by the flow at the critical height. Then, the nonseparated sheltering works also at this high wave age.
Parallel and lower hybrid turbulence in low β plasmas driven by strong parallel currents and the resulting parallel electron and perpendicular ion energization
Authors: McMillan Ben F. , Cairns Iver H.
Published: January 2007

In plasmas with strong field aligned currents, the most unstable mode is not always at parallel propagation, but may be at intermediate and very oblique angles. 2D particle simulations are performed in order to examine the interaction between the plasma waves at various angles and the electron and ion distributions in low β collisionless plasmas with strong electron drifts. The parallel Buneman instability is known to arise in this situation, but the simulations demonstrate that the very oblique lower hybrid (LH) waves, until recently considered unimportant, may actually play a role just as significant as the waves at parallel propagation. The LH waves are energized by a current-driven linear instability, which may be seen as the oblique limit of the Buneman or ion-acoustic instability. The simulations resolve strong LH turbulence, substantial perpendicular ion tail heating and parallel electron heating. The combined action of parallel and oblique modes results in more complete electron relaxation than may be produced by the parallel Buneman instability alone.
Stationary coaxial electrified jet of a dielectric liquid surrounded by a conductive liquid
Authors: Higuera F. J.
Published: January 2007

The electrohydrodynamic problem describing the evolution of a coaxial jet of two immiscible Newtonian liquids injected through concentric orifices into a region of uniform electric field is formulated in the framework of the leaky dielectric model, and the dimensionless parameters governing the flow are identified. A simplified model is proposed combining a quasi-uni-directional approximation for the flow and the transport of electric charge with a fully numerical evaluation of the electric field. Results of this model are compared with boundary element solutions of the full governing equations for viscosity-dominated flows. The current/flow rate characteristic of a coaxial viscosity-dominated jet is computed and the ranges of flow rates in which a stationary axisymmetric jet is realized are discussed in the case of an outer liquid of finite electrical conductivity surrounding a dielectric liquid, in which the electric shear that stretches the jet is concentrated at its outer surface. The dependence of the flow on the applied electric field and the flow rates of the liquids, as well as the effects of the viscosity and electrical conductivity of the inner liquid, and of the surface tension of the inner surface, are discussed.
Fast marching methods for the continuous traveling salesman problem
Authors: Andrews June , Sethian J. A.
Published: January 2007

We consider a problem in which we are given a domain, a cost function which depends on position at each point in the domain, and a subset of points (“cities”) in the domain. The goal is to determine the cheapest closed path that visits each city in the domain once. This can be thought of as a version of the traveling salesman problem, in which an underlying known metric determines the cost of moving through each point of the domain, but in which the actual shortest path between cities is unknown at the outset. We describe algorithms for both a heuristic and an optimal solution to this problem. The complexity of the heuristic algorithm is at worst caseM·NlogN, whereMis the number of cities, andNthe size of the computational mesh used to approximate the solutions to the shortest paths problems. The average runtime of the heuristic algorithm is linear in the number of cities andO(NlogN) in the sizeNof the mesh.
The crystal structure of the
Escherichia coli
AmtB–GlnK complex reveals how GlnK regulates the ammonia channel
Authors: Conroy Matthew J. , Durand Anne , Lupo Domenico , Li Xiao-Dan , Bullough Per A. , Winkler Fritz K. , Merrick Mike
Published: January 2007

Amt proteins are ubiquitous channels for the conduction of ammonia in archaea, eubacteria, fungi, and plants. In
Escherichia coli
, previous studies have indicated that binding of the P
II
signal transduction protein GlnK to the ammonia channel AmtB regulates the channel thereby controlling ammonium influx in response to the intracellular nitrogen status. Here, we describe the crystal structure of the complex between AmtB and GlnK at a resolution of 2.5 Å. This structure of P
II
in a complex with one of its targets reveals physiologically relevant conformations of both AmtB and GlnK. GlnK interacts with AmtB almost exclusively via a long surface loop containing Y51 (T-loop), the tip of which inserts deeply into the cytoplasmic pore exit, blocking ammonia conduction. Y51 of GlnK is also buried in the pore exit, explaining why uridylylation of this residue prevents complex formation.
Dual Lipid Modification of Arabidopsis Gγ-Subunits Is Required for Efficient Plasma Membrane Targeting
Authors: Zeng Qin , Wang Xuejun , Running Mark P.
Published: January 2007

Posttranslational lipid modifications are important for proper localization of many proteins in eukaryotic cells. However, the functional interrelationships between lipid modification processes in plants remain unclear. Here we demonstrate that the two heterotrimeric G-protein γ-subunits from Arabidopsis (Arabidopsis thaliana), AGG1 and AGG2, are prenylated, and AGG2 is S-acylated. In wild type, enhanced yellow fluorescent protein-fused AGG1 and AGG2 are associated with plasma membranes, with AGG1 associated with internal membranes as well. Both can be prenylated by either protein geranylgeranyltransferase I (PGGT-I) or protein farnesyltransferase (PFT). Their membrane localization is intact in mutants lacking PFT activity and largely intact in mutants lacking PGGT-I activity but is disrupted in mutants lacking both PFT and PGGT-I activity. Unlike in mammals, Arabidopsis Gγs do not rely on functional Gα for membrane targeting. Mutation of the sixth to last cysteine, the putative S-acylation acceptor site, causes a dramatic change in AGG2 but not AGG1 localization pattern, suggesting S-acylation serves as an important additional signal for AGG2 to be targeted to the plasma membrane. Domain-swapping experiments suggest that a short charged sequence at the AGG2 C terminus contributes to AGG2's efficient membrane targeting compared to AGG1. Our data show the large degree to which PFT and PGGT-I can compensate for each other in plants and suggest that differential lipid modification plays an important regulatory role in plant protein localization.
GlutathioneS-Transferase Interacting with Far-Red Insensitive 219 Is Involved in Phytochrome A-Mediated Signaling in Arabidopsis
Authors: Chen Ing-Chien , Huang I-Ching , Liu Ming-Jung , Wang Zhi-Gong , Chung Shu-Shiang , Hsieh Hsu-Liang
Published: January 2007

Far-red (FR) insensitive 219 (FIN219) was previously shown to be involved in phytochrome A-mediated FR light signaling. To further understand its function and regulatory relation with other light-signaling components, a yeast two-hybrid approach was used to isolate FIN219-interacting partners. Here, we demonstrate that FIN219-interacting protein 1 (FIP1) interacts with FIN219 in vitro and in vivo and is composed of 217 amino acids that belong to the tau class of the large glutathione S-transferase gene family. FIP1 was further shown to have glutathione S-transferase activity. The gain of function and partial loss of function of FIP1 resulted in a hyposensitive hypocotyl phenotype under continuous FR (cFR) light and a delayed flowering phenotype under long-day conditions, which suggests that FIP1 may exist in a complex to function in the regulation of Arabidopsis (Arabidopsis thaliana) development. In addition, FIP1 mRNA was down-regulated in the suppressor of phytochrome A-105 1 mutant and differentially expressed in constitutive photomorphogenic 1-4 (cop1-4) and cop1-5 mutants under cFR. Intriguingly, FIP1 expression was up-regulated in the fin219 mutant under all light conditions, except cFR. Furthermore, promoter activity assays revealed that FIP1 expression was light dependent, mainly associated with vascular tissues, and developmentally regulated. Subcellular localization studies revealed that the β-glucuronidase-FIP1 fusion protein was localized in the nucleus and cytoplasm. Taken together, these data indicate that FIP1 may interact with FIN219 to regulate cell elongation and flowering in response to light.
PIP5K9, an Arabidopsis Phosphatidylinositol Monophosphate Kinase, Interacts with a Cytosolic Invertase to Negatively Regulate Sugar-Mediated Root Growth
Authors: Lou Ying , Gou Jin-Ying , Xue Hong-Wei
Published: January 2007

Phosphatidylinositol monophosphate 5-kinase (PIP5K) plays an essential role in coordinating plant growth, especially in response to environmental factors. To explore the physiological function of PIP5K, we characterized Arabidopsis thaliana PIP5K9, which is constitutively expressed. We found that a T-DNA insertion mutant, pip5k9-d, which showed enhanced PIP5K9 transcript levels, had shortened primary roots owing to reduced cell elongation. Transgenic plants overexpressing PIP5K9 displayed a similar root phenotype. Yeast two-hybrid assays identified a cytosolic invertase, CINV1, that interacted with PIP5K9, and the physiological relevance of this interaction was confirmed by coimmunoprecipitation studies using plant extracts. CINV1-deficient plants, cinv1, had reduced activities of both neutral and acid invertases as well as shortened roots. Invertase activities in pip5k9-d seedlings were also reduced, suggesting a negative regulation of CINV1 by PIP5K9. In vitro studies showed that PIP5K9 interaction indeed repressed CINV1 activities. Genome-wide expression studies revealed that genes involved in sugar metabolism and multiple developmental processes were altered in pip5k9-d and cinv1, and the altered sugar metabolism in these mutants was confirmed by metabolite profiling. Together, our results indicate that PIP5K9 interacts with CINV1 to negatively regulate sugar-mediated root cell elongation.
A Novel Transcriptional Cascade Regulating Expression of Heat Stress Proteins during Seed Development ofArabidopsis
Authors: Kotak Sachin , Vierling Elizabeth , Bäumlein Helmut , Koskull-Döring Pascal von
Published: January 2007

Within the Arabidopsis thaliana family of 21 heat stress transcription factors (Hsfs), HsfA9 is exclusively expressed in late stages of seed development. Here, we present evidence that developmental expression of HsfA9 is regulated by the seed-specific transcription factor ABSCISIC ACID–INSENSITIVE3 (ABI3). Intriguingly, ABI3 knockout lines lack detectable levels of HsfA9 transcript and protein, and further ectopic expression of ABI3 conferred the ability to accumulate HsfA9 in response to abscisic acid in transgenic plantlets. Consequently, the most abundant heat stress proteins (Hsps) in seeds (Hsp17.4-CI, Hsp17.7-CII, and Hsp101) were not detectable in the ABI3 knockout lines, but their expression could be detected in plants ectopically expressing HsfA9 in vegetative tissues. Furthermore, this seed-specific transcription factor cascade was reconstructed in transient β-glucuronidase reporter assays in mesophyll protoplasts by showing that ABI3 could activate the HsfA9 promoter, whereas HsfA9 in turn was shown to be a potent activator on the promoters of Hsp genes. Thus, our study establishes a genetic framework in which HsfA9 operates as a specialized Hsf for the developmental expression of Hsp genes during seed maturation.
Repression of Flowering inArabidopsisRequires Activation ofFLOWERING LOCUS CExpression by the Histone Variant H2A.Z
Authors: Deal Roger B. , Topp Christopher N. , McKinney Elizabeth C. , Meagher Richard B.
Published: January 2007

The histone variant H2A.Z has been implicated in numerous chromatin-mediated processes, including transcriptional activation, euchromatin maintenance, and heterochromatin formation. In yeast and humans, H2A.Z is deposited into chromatin by a conserved protein complex known as SWR1 and SRCAP, respectively. Here, we show that mutations in the Arabidopsis thaliana homologs of two components of this complex, ACTIN-RELATED PROTEIN6 (ARP6) and PHOTOPERIOD-INDEPENDENT EARLY FLOWERING1 (PIE1), produce similar developmental phenotypes and result in the misregulation of a common set of genes. Using H2A.Z-specific antibodies, we demonstrate that ARP6 and PIE1 are required for the deposition of H2A.Z at multiple loci, including the FLOWERING LOCUS C (FLC) gene, a central repressor of the transition to flowering. Loss of H2A.Z from chromatin in arp6 and pie1 mutants results in reduced FLC expression and premature flowering, indicating that this histone variant is required for high-level expression of FLC. In addition to defining a novel mechanism for the regulation of FLC expression, these results support the existence of a SWR1-like complex in Arabidopsis and show that H2A.Z can potentiate transcriptional activation in plants. The finding that H2A.Z remains associated with chromatin throughout mitosis suggests that it may serve an epigenetic memory function by marking active genes and poising silenced genes for reactivation.
The influence of below‐ground herbivory and defoliation of a legume on nitrogen transfer to neighbouring plants
Authors: AYRES E. , DROMPH K. M. , COOK R. , OSTLE N. , BARDGETT R. D.
Published: January 2007

Both foliar and root herbivory can alter the exudation of carbon from plant roots, which in turn can affect nitrogen availability in the soil. However, few studies have investigated the effects of herbivory on N fluxes from roots, which can directly increase N availability in the soil and uptake by neighbouring plants. Moreover, the combined effects of foliar and root herbivory on N fluxes remains unexplored.

We subjected the legume white clover (Trifolium repens L.) to defoliation (through clipping) and root herbivory (by an obligate root‐feeding nematode, Heterodera trifolii Goggart) to examine how these stresses individually, and simultaneously, affected the transfer of T. repens‐derived N to neighbouring perennial ryegrass (Lolium perenne L.) plants using 15N stable‐isotope techniques. We also examined the effects of defoliation and root herbivory on the size of the soil microbial community and the growth response of L. perenne.

Neither defoliation nor root herbivory negatively affected T. repens biomass. On the contrary, defoliation increased root biomass (34%) and total shoot production by T. repens (100%). Furthermore, defoliation resulted in a fivefold increase in T. repens‐derived 15N recovered in L. perenne roots, and increased the size of the soil microbial biomass (77%). In contrast, root herbivory by H. trifolii slightly reduced 15N transfer from T. repens to L. perenne when T. repens root 15N concentration was included as a covariate, and root herbivory did not affect microbial biomass. Growth of L. perenne was not affected by any of the treatments.

Our findings demonstrate that defoliation of a common grassland legume can substantially increase the transfer of its N to neighbouring plants by directly affecting below‐ground N fluxes. These finding require further examination under field conditions but, given the prevalence of N‐limitation of plant productivity in terrestrial ecosystems, increased transfer of N from legumes to non‐N‐fixing species could alter competitive interactions, with implications for plant community structure.
Reporting bad news on software projects: the effects of culturally constituted views of face‐saving
Authors: Keil Mark , Im Ghi Paul , Mähring Magnus
Published: January 2007

Abstract. The reluctance to report bad news about a project and its status is a known problem in software project management that can contribute to project failure. The reluctance to report bad news is heightened when it bears personal risks. Oftentimes, those who report bad news end up losing face. In extreme cases, they not only lose face, but may end up on the unemployment line. The need to preserve face is a powerful influence on social behaviour. While universal, it manifests itself differently in different cultures. To date, there have been no empirical studies of the extent to which culturally constituted views of face‐saving affect reporting of bad news on software projects. This is a particularly important topic given the increased prevalence of global, dispersed software development teams and offshore outsourcing of software development. In this study, we conducted a role‐playing experiment in the USA and in South Korea, to investigate the effect of culturally constituted views of face‐saving on the willingness to report bad news regarding a software development project. A blame‐shifting opportunity was chosen as the means to operationalize face‐saving in a culturally sensitive fashion. The two countries were chosen because they differ markedly in their views of face‐saving and the relative importance ascribed to two important aspects of face: lian and mianzi. Results reveal that the presence of a blame‐shifting opportunity had a significant effect on US subjects’ willingness to report bad news, but the effect on Korean subjects was not found to be statistically significant. In the absence of a blame‐shifting opportunity, we did not observe any significant differences between US and Korean subjects in willingness to report bad news. The implications of these findings are discussed.
Directly observed therapy and tuberculosis: how can a systematic review of qualitative research contribute to improving services? A qualitative meta‐synthesis
Authors: Noyes Jane , Popay Jennie
Published: January 2007

Title. Directly observed therapy and tuberculosis: how can a systematic review of qualitative research contribute to improving services? A qualitative meta‐synthesis

Aim.  This paper reports the findings from a qualitative meta‐synthesis concerning people with, or at risk of, tuberculosis, service providers and policymakers and their experiences and perceptions of tuberculosis and treatment.

Background.  Directly observed therapy is part of a package of interventions to improve tuberculosis treatment and adherence. A Cochrane systematic review of trials showed an absence of evidence for or against directly observed therapy compared with people treating themselves.

Method.  Qualitative systematic review methods were used to search, screen, appraise and extract data thematic analysis was used to synthesize data from 1990 to 2002, and an update of literature to December 2005. Two questions were addressed: ‘What does qualitative research tell us about the facilitators and barriers to accessing and complying with tuberculosis treatment?’ and ‘What does qualitative research tell us about the diverse results and effect sizes of the randomized controlled trials included in the Cochrane review?’ Findings help explain the diverse trial results in a Cochrane systematic review of directly observed therapy and tuberculosis and consider implications for research, policy and practice.

Findings.  Five themes emerged from the 1990 to 2002 synthesis: socio‐economic circumstances, material resources and individual agency; explanatory models and knowledge systems in relation to tuberculosis and its treatment; the experience of stigma and public discourses around tuberculosis; sanctions, incentives and support, and the social organization and social relationships of care. Two additional themes emerged from the 2005 update.

Conclusion.  The qualitative meta‐synthesis improved the relevance and scope of the Cochrane review of trials. The findings make a major contribution to the development of theory concerning global WHO‐branded disease control and the practicality of local delivery to people.
Scaffolding online argumentation during problem solving
Authors: Oh S. , Jonassen D.H.
Published: January 2007

Abstract In this study, constraint‐based argumentation scaffolding was proposed to facilitate online argumentation performance and ill‐structured problem solving during online discussions. In addition, epistemological beliefs were presumed to play a role in solving ill‐structured diagnosis–solution problems. Constraint‐based discussion boards were implemented to scaffold pre‐service teachers' online discussions about behaviour management (diagnosis–solution) problems. The scaffolded discussion group generated more evidence notes and also generated more hypothesis messages and hypothesis testing messages as well as problem space construction messages. There was a relationship between epistemological beliefs and ill‐structured problem solving. Simple knowledge, omniscient authority, and fixed ability significantly predicted problem‐solving performance. A significant negative relationship between simple knowledge and individual problem‐solving performance was found. This implies that individuals who believe in simple knowledge may be less inclined to explore more solution alternatives. However, contrary to prediction, omniscient authority and fixed ability beliefs were positively associated with problem‐solving processes.
What strategies are effective for formative assessment in an e‐learning environment?
Authors: Wang T.H.
Published: January 2007

Abstract  The web‐based formative assessment developed in this research is named Formative Assessment Module of the Web‐based Assessment and Test Analysis System (FAM‐WATA). FAM‐WATA is a multiple‐choice web‐based formative assessment module containing six effective strategies: ‘repeat the test’, ‘correct answers are not given’, ‘query scores’, ‘ask questions’, ‘monitor answering history’, and ‘all pass and then reward’. This research explored the effectiveness of FAM‐WATA, cognitive styles and e‐learning, and student attitudes towards the six strategies of FAM‐WATA. A total of 503 seventh‐grade students in central Taiwan were valid in this research. Overall results indicated that students displayed a positive attitude towards the six strategies of FAM‐WATA. In addition, results also showed that students in an e‐learning environment equipped with FAM‐WATA achieved better learning effectiveness, and that field independent students appeared to make better use of FAM‐WATA strategies than field dependent students. This research concluded that FAM‐WATA benefited student learning in an e‐learning environment.
Temporal trends in the incidence of HIV infection in antenatal clinic attendees in Addis Ababa, Ethiopia, 1995–2003
Authors: Wolday D. , Meles H. , Hailu E. , Messele T. , Mengistu Y. , Fekadu M. , Parekh B. S. , Wuhib T.
Published: January 2007

Background.  The HIV incidence data are relevant in depicting the current dynamics and trend of the epidemic. Using a new laboratory method for HIV‐1 incidence, we aimed at estimating a 10‐year trend in HIV‐1 incidence in Addis Ababa, Ethiopia.

Methods.  We determined the temporal trends in HIV incidence based on a total of 7744 serum specimens from pregnant women who attended antenatal clinics in Addis Ababa between 1995 and 2003. HIV incidence was determined by IgG‐capture HIV‐1 BED incidence enzyme immunoassay following a validation using a well‐characterized panel of serial serum specimens from subtype C‐infected seroconverters.

Findings.  Of the 1350 HIV+ specimens tested as part of the annual sentinel survey between 1995 and 2003, a total of 1332 (98.7%) were tested by BED HIV‐1 incidence assay. The incidence rate of HIV‐1 infection declined significantly from 7.7% (95% CI, 3.9–11.5%) in 1995 to 2.0% (95% CI, 0.7–3.3%) in 2003. Although there was a trend, amongst the age group of 15–29 years, in age‐specific decline in incidence, it was not statistically significant. No change in HIV incidence rate was observed for the group aged above 30 years.

Interpretation.  A corresponding decline in the incidence of HIV infection was observed with the decline in the prevalence of HIV infection between 1995 and 2003 in Addis Ababa City. Whether the declines were because of changes in sexual behaviours or other reasons needs to be explored. The BED HIV‐1 incidence assay provides a valuable tool in obtaining information on recent HIV‐1 infection.
Is susceptibility to severe infection in low‐income countries inherited or acquired?
Authors: Aaby P.
Published: January 2007

From a low‐income country perspective, we need to emphasize factors which affect acquired susceptibility to severe infection. Such factors may lend themselves to modification by public health interventions. The present paper reviews the experience with understanding the causes of severe measles infection and the impact of health interventions in Guinea‐Bissau over a 28‐year period. In the 1970s, acquired susceptibility because of malnutrition was considered to be the main cause of high mortality. However, we found no association between nutritional status and subsequent risk of dying of measles. Instead, crowding and intensity of exposure were the main determinants of severe measles. Factors related to transmission have been substantiated for measles, chickenpox, whooping cough and polio. We found measles vaccination to be associated with a major reduction in mortality, particularly for girls. This suggested that measles vaccine has a beneficial nontargeted immune stimulatory effect. The importance of nontargeted effects was clearly documented when World Health Organization introduced a new high‐titre measles vaccine (HTMV). HTMV was fully protective but associated with twofold higher mortality for girls. Bacille Calmette Guérin (BCG), diphtheria–tetanus–pertussis (DTP) and oral polio vaccine (OPV) have also shown nontargeted effects, the effect being beneficial for BCG and OPV but negative for DTP. Both beneficial and negative effects are strongest for girls. There are many acquired factors, which affect susceptibility to infection in ways which have not been explored by medical science. They may have a major impact on child survival in low‐income countries.
Mechanisms of exercise‐induced ST‐segment depression in patients without typical angina pectoris
Authors: Sundkvist G. M. G. , Hjemdahl P. , Kahan T. , Melcher A.
Published: January 2007

Objective.  To evaluate if exercise‐induced ST‐segment depression without typical angina pectoris is related to increases in sympatho‐adrenal activity or β‐adrenoceptor sensitivity.

Patients.  Thirteen patients (four men) aged 35–62 years with ST‐segment depression during exercise but atypical symptoms and normal myocardial scintigraphy, and 13 matched controls.

Design and interventions.  Patients and controls were compared regarding responses with: (i) exercise testing without treatment, (ii) exercise testing following β‐adrenoceptor blockade by propranolol (0.15 mg kg−1 i.v.), (iii) incremental adrenaline infusions (0.1, 0.2, 0.4 and 0.8 nmol kg−1 min−1) and (iv) adrenaline infusions during α‐adrenoceptor blockade by phentolamine (0.5 mg min−1).

Main outcome measures.  ST‐segment depression and tissue Doppler parameters reflecting contractility.

Results.  Exercise lowered the ST‐segment by 2.44 mm without and 0.87 mm with β‐adrenoceptor blockade (P < 0.001 for difference) amongst patients, but not amongst controls. Maximal heart rate was slightly higher amongst patients (P < 0.05), despite similar loads and plasma catecholamine responses to exercise in the two groups; this difference disappeared after β‐adrenoceptor blockade with propranolol. ST‐segment depression during adrenaline infusion was greater in patients compared with controls (P < 0.01) despite similar increases in heart rate. α‐Blockade enhanced the ST‐segment depression (P < 0.001) and heart rate (P < 0.001) responses to adrenaline infusion more markedly amongst patients. Tissue Doppler imaging showed similar contractility and diastolic relaxation responses of patients and controls to adrenaline, but early diastolic movements did not increase amongst patients after phentolamine (P < 0.01).

Conclusions.  Exercise‐induced ST‐segment depression in patients with a low likelihood of ischaemic heart disease is related to increased β‐adrenergic sensitivity regarding chronotropic and electrophysiological, but not inotropic responses.
Intracoronary enalaprilat during angioplasty for acute myocardial infarction: alleviation of postischaemic neurohumoral and inflammatory stress?
Authors: Schaefer U. , Kurz T. , Bonnemeier H. , Dendorfer A. , Hartmann F. , Schunkert H. , Richardt G.
Published: January 2007

Aims.  Reperfusion after myocardial ischaemia is associated with a distinct ischaemia/reperfusion injury. Since ACE‐inhibition, beyond its influence on cardiac angiotensin II formation and kinin metabolism, has been shown to be cardioprotective by decreasing leucocyte adhesion and endothelin‐1 (ET‐1) release, we investigated the effects of intracoronary (i.c.) enalaprilat during primary angioplasty in acute myocardial infarction.

Methods and Results.  Twenty‐two patients were randomized to receive i.c. enalaprilat (50 μg) or placebo immediately after reopening of the infarct‐related artery (IRA). Plasma concentrations of soluble L‐selectin, P‐selectin, intercellular adhesion molecule‐1 (sICAM‐1), vascular cell adhesion molecule‐1 (sVCAM‐1), ET‐1 and nitric oxide metabolite concentrations (NO(x)) were measured in pulmonary arterial blood. Coronary blood flow was assessed using corrected thrombolysis in myocardial infarction (TIMI) frame counts (CTFC). During reperfusion, there was a significant increase in sL‐selectin, sP‐selectin and ET‐1 in the placebo group, which was greatly diminished by enalaprilat. Levels of sVCAM‐1 and sICAM‐1 were not affected in either group. CTFC in the placebo group remained higher than normal in both the IRA and nonculprit vessels, whereas myocardial blood flow improved with enalaprilat.

Conclusion.  Enalaprilat as adjunct to primary angioplasty might be a protective approach to prevent leucocyte adhesion and the release of ET‐1, thereby improving coronary blood flow.