bluuebunny/crossref_metadata_2025 huggingface dataset:
Depth dependent dynamics in the hydration shell of a protein
Authors: Servantie J. , Atilgan C. , Atilgan A. R.
Published: August 2010

We study the dynamics of hydration water/protein association in folded proteins using lysozyme and myoglobin as examples. Extensive molecular dynamics simulations are performed to identify underlying mechanisms of the dynamical transition that corresponds to the onset of amplified atomic fluctuations in proteins. The results indicate that the number of water molecules within a cutoff distance of each residue scales linearly with protein depth index and is not affected by the local dynamics of the backbone. Keeping track of the water molecules within the cutoff sphere, we observe an effective residence time, scaling inversely with depth index at physiological temperatures while the diffusive escape is highly reduced below the transition. A depth independent orientational memory loss is obtained for the average dipole vector of the water molecules within the sphere when the protein is functional. While below the transition temperature, the solvent is in a glassy state, acting as a solid crust around the protein, inhibiting any large scale conformational fluctuations. At the transition, most of the hydration shell unfreezes and water molecules collectively make the protein more flexible.
Contraction and extension of Vorticella and its mechanical characterization under flow loading
Authors: Nagai Moeto , Asai Hiroshi , Fujita Hiroyuki
Published: August 2010

We have studied the contraction and extension of Vorticella convallaria and its mechanical properties with a microfluidic loading system. Cells of V. convallaria were injected to a microfluidic channel (500 μm in width and 100 μm in height) and loaded by flow up to ∼350 mm s−1. The flow produced a drag force on the order of nanonewton on a typical vorticellid cell body. We gradually increased the loading force on the same V. convallaria specimen and examined its mechanical property and stalk motion of V. convallaria. With greater drag forces, the contraction distance linearly decreased; the contracted length was close to around 90% of the stretched length. We estimated the drag force on Vorticella in the channel by calculating the force on a sphere in a linear shear flow.
Effects of gold nanoparticles on electro-optical properties of a polymer-dispersed liquid crystal
Authors: Hinojosa Alfonso , Sharma Suresh C.
Published: August 2010

We present evidence for relatively large changes in the electro-optical properties of a polymer-dispersed liquid crystal (PDLC) due to inclusion of small concentrations of 14 nm diameter Au-nanoparticles (NPs). We observe that NPs lower switch-on electric field, increase optical transmission at certain voltages, and influence the frequency response of the PDLC.
Thermodynamic model for heterogeneous bubble nucleation in a temperature gradient
Authors: Wu Di , Duan Yuan-Yuan , Yang Zhen
Published: August 2010

A thermodynamic model for heterogeneous bubble nucleation was developed to include the effect of the fluid temperature gradient next to a heated wall. An increase of the wall temperature gradient (heat flux) is shown to suppress bubble nucleation or increase the superheat needed for nucleation. Bubble nucleation is completely suppressed above a critical temperature gradient. The onset of nucleate boiling is shown to be related to the intersection of the qw″−Tw curve of the boiling system and the qw,c″−Tw curve of the fluid. The theoretical predictions agree with experimental results.
Computational fluid dynamics analysis of a twisted three-bladed H-Darrieus rotor
Authors: Gupta R. , Biswas Agnimitra
Published: August 2010

A steady-state two-dimensional computational fluid dynamics analysis was performed using FLUENT 6.2 software to analyze the performance of a twisted three-bladed H-Darrieus rotor. The flow over the rotor was simulated by using unstructured-mesh finite volume method coupled with moving mesh technique to solve mass and momentum conservation equations. The standard k-ε turbulence model was chosen. Second-order upwind discretization scheme was adopted for pressure-velocity coupling of the flow. The aerodynamic coefficients, such as lift coefficient, drag coefficient, and lift-to-drag coefficient, were evaluated with respect to angle of attack for two chord Reynolds numbers. The power coefficient of the rotor was also evaluated. The results were validated by using experimental values for the twisted three-bladed H-Darrieus rotor. The experiments were earlier conducted in a subsonic wind tunnel available in the department. The results showed good matching between the two approaches. The effect of twist angle at the chord ends on the performance of the rotor was also evaluated.
Communication: An extended model of liquid bridging
Authors: Saija F. , Aliotta F. , Fontanella M. E. , Pochylski M. , Salvato G. , Vasi C. , Ponterio R. C.
Published: August 2010

Recent phenomenological studies have drawn attention to an appealing effect, observed for the first time in 1893, today known as water-bridge. The phenomenon has been ascribed to unknown properties of water. We report some experimental results showing that, contrary to a widely common belief, the phenomenon is not to be related with water neither with a property of hydrogen bonded networks. Using a very simple model, we show that the liquid bridge phenomenon is originated by electrostatic effects and can be reproduced in any dense fluid with no respect of its peculiar molecular properties. This basic approach is able to reproduce many of the experimentally observed features of the bridge formation. In perspective of future investigations, the possible phenomena responsible of the bridge stability, after its formation, are briefly discussed.
Oxygen migration at Pt/HfO2/Pt interface under bias operation
Authors: Nagata T. , Haemori M. , Yamashita Y. , Yoshikawa H. , Iwashita Y. , Kobayashi K. , Chikyow T.
Published: August 2010

The interfacial electronic states of a Pt/HfO2/Pt diode were investigated by using hard x-ray photoelectron spectroscopy under bias operation. The application of a forward bias to the Pt/HfO2/Pt diode increased the Pt–O bonding peak, providing evidence of Pt electrode oxidization and oxygen vacancy formation around the Pt/HfO2 interface. Under a reverse bias, hafnium was drawn to the Pt electrode, where it took part in Hf–Pt bonding. We achieved the direct observation of oxygen migration at a Pt/HfO2 interface under device operation, which is the key to controlling the electrical properties of metals on oxides.
Electron spin relaxation time in GaAs/AlGaAs multiple quantum wells grown on slightly misoriented GaAs(110) substrates
Authors: Koh Shinji , Nakanishi Akira , Kawaguchi Hitoshi
Published: August 2010

We measured the electron spin relaxation times τs in GaAs/AlGaAs multiple quantum wells (MQWs) grown on slightly misoriented GaAs(110) substrates. The τs of the MQW on misoriented GaAs(110) decreased when the misorientation angles were increased. The bulk inversion asymmetry component of the D’yakonov–Perel’ spin relaxation in the misoriented (110) MQWs was calculated to verify the origin of the decrease in the τs. A comparison between the experimental and calculated results revealed that the decrease in the τs was attributed to the emergence of in-plane effective magnetic fields in the (110) MQWs due to the misorientation.
Direct measurement of rotationally resolved H2 Q-branch Raman coherence lifetimes using time-resolved picosecond coherent anti-Stokes Raman scattering
Authors: Kulatilaka Waruna D. , Hsu Paul S. , Stauffer Hans U. , Gord James R. , Roy Sukesh
Published: August 2010

We report direct measurement of H2 Q-branch Raman coherence lifetimes using time-resolved picosecond coherent anti-Stokes Raman scattering (ps-CARS). A custom-built, high-peak-power, nearly transform-limited ps laser system offers an ideal combination of frequency and temporal resolution for such measurements. The coherence lifetimes measured for pure H2 at room temperature are in good agreement with decay rates that were derived from previous high-resolution studies. Measurements were also performed in binary mixtures of H2–X (X=Ar, N2, CH4, and C2H4). These measurements can be useful for accurate H2 ps-CARS thermometry as well as for studying various H2 collisional energy-transfer processes.
Anti-Müllerian hormone: a predictive marker of embryo production in cattle?
Authors: Monniaux Danielle , Barbey Sarah , Rico Charlène , Fabre Stéphane , Gallard Yves , Larroque Hélène
Published: August 2010

In cattle, the embryo production rate after superovulation varies between individuals and is difficult to predict. Recently, we proposed that anti-Müllerian hormone (AMH) plasma levels measured before treatment can help predict superovulatory responses. To establish whether blood measurement of AMH can help predict the number of embryos produced by a given cow after superovulation, data collected over 4 years from 45 dairy cows submitted to repeated embryo production were analysed in a retrospective study. A high within-animal repeatability (0.38 and 0.36) and a strong effect of the father of the donor cow (P < 0.01) were observed for the numbers of collected and transferable embryos, respectively. AMH concentration, measured in the plasma of donor cows during first lactation and several months before the start of the embryo production campaigns, was found to be highly correlated with the maximal number of collected (P < 0.0001) and transferable (P < 0.01) embryos per cow. In conclusion, the capacity of embryo production is a repeatable and probably heritable trait in the cow, and blood measurement of AMH in potential donor cows could be of value in determining a cow’s intrinsic capacity to produce transferable embryos.
Development of novel strategies for the isolation of piglet testis cells with a high proportion of gonocytes
Authors: Yang Yanfei , Yarahmadi Mehran , Honaramooz Ali
Published: August 2010

Gonocytes have germline stem cell potential and are present in the neonatal testis, comprising 5–10% of freshly isolated testis cells. Maximising the number and proportion of gonocytes among freshly isolated testis cells will greatly facilitate their subsequent purification and in vitro study and manipulation. Seven experiments were conducted to evaluate the effects of multiple factors on the efficiency of testis cell isolation from neonatal pigs. We found that the use of a lysis buffer led to elimination of erythrocytes without adversely affecting testis cell isolation. Approximately ninefold as many live cells could be harvested by enzymatic digestion of testis tissues compared with mechanical methods. Digestion with collagenase–hyaluronidase–DNase followed by trypsin resulted in the highest recovery of live cells. However, the proportion of gonocytes (∼7%) did not differ between the mechanical and enzymatic methods of testis cell isolation. Pretreatment of the tissue with cold enzymes increased the recovery of live testis cells. New strategies of combining a gentle enzymatic digestion with two rounds of vortexing resulted in the isolation of testis cells with very high gonocyte proportion. The efficiency of these novel methods could be further optimised to collect testis cells with a gonocyte proportion of approximately 40%. This novel three-step testis cell isolation strategy can be completed within 1 h and can harvest approximately 17 × 106 live gonocytes per g testis tissue. Therefore, in addition to elucidating the effects of several factors on testis cell isolation, we developed a novel strategy for the isolation of testis cells that yielded approximately 40% gonocytes in the freshly isolated cells (i.e. four- to eight-fold higher than the proportions obtained using current strategies). This strategy has instant applications in the purification of gonocytes.
Developing pragmatic fluency in an EFL context
Authors: Barón Julia , Celaya M. Luz
Published: August 2010

Studies on pragmatic development, especially on the development of pragmatic fluency, are still scarce in the area of Interlanguage Pragmatics. The present study analyses whether EFL learners (N = 144), from Primary to University levels, who have not been instructed in pragmatics nevertheless show development in pragmatic fluency. A wide variety of measures were used to analyse the learners’ production in open role-play. The results in the present study show that pragmatic fluency indeed develops as proficiency increases (the learners develop their use of gambits and routines, they are capable of changing topics by themselves and they produce appropriate time responses) but also that, in contrast, the development in the use of patterns stops at Grade 11 and there is no development in the opening and the closing phases. These results are discussed in the light of cognitive models of second language acquisition.
Pragmaticalisation des adverbes temporels dans le français parlé L1 et L2
Authors: Hancock Victorine , Sanell Anna
Published: August 2010

Nous partons dans cette étude de la polysémie d’un certain nombre d’adverbes temporels récurrents en français L1. Cette polysémie serait le résultat d’un développement diachronique (Dostie 2004, Hansen & Rossari 2005, Pusch 2006). Nous nous intéressons ici au développement des adverbes déjà, encore, toujours, alors, après, et maintenant dans le français parlé L2 chez des apprenants avancés. Nous faisons l’hypothèse que ces adverbes, à mesure que la L2 se développe, sont de plus en plus pragmaticalisés. Par pragmaticalisation, nous entendons ici le développement des fonctions temporelles et discursives et/ou énonciatives des adverbes chez les locuteurs suédophones en français L2.
Discourse cohesion and Topic discontinuity in native and learner production
Authors: Benazzo Sandra , Andorno Cecilia
Published: August 2010

In order to realize text cohesion, speakers have to select specific information units and mark their informational status within the discourse; this results in specific, language-particular perspective-taking, linked to typological differences (Slobin 1996). A previous study on native speakers’ production in French, Italian, German and Dutch (Dimroth et al., in press) has highlighted a “Romance way” and a “Germanic way” of marking text cohesion in narrative segments involving topic discontinuity. In this paper we analyze how text cohesion is realized in the same contexts by advanced learners of L2 French (Italian and German L1) and L2 Italian (French and German L1). Our aim is to verify the hypothesis of an L2 advanced stage where learners manage the target language utterance grammar whereas their discourse organization still reflects L1 preferences. The results confirm the persistent presence of L1 influence, but they also show learner-specific tendencies (favouring lexical means over morphosyntactic ones), which are independent of their source language.
The lexicon-syntax interface in child L2 grammars of Italian
Authors: Kraš Tihana
Published: August 2010

This paper investigates the knowledge of two unaccusative diagnostics in ­Italian, auxiliary selection and ne cliticisation, in child L2 grammars of L1 Croatian speakers. The two phenomena are not instantiated in Croatian. Following ­Sorace (2000), it is assumed in the paper that the lexical-semantic aspect of these phenomena is characterised by gradience that can be captured by the Auxiliary Selection Hierarchy. Findings are reported of an experimental study in which highly proficient child L2 learners and their monolingual peers rated the acceptability of two Italian auxiliaries and ne-cliticisation with different lexical-semantic classes of intransitives by using the Magnitude Estimation technique. The learners’ judgements largely converged on those of the native speakers, suggesting that the two phenomena had been acquired in the L2. Such findings support the hypothesis predicting complete L2 acquisition of properties pertaining to an interface between two domains within the language factory (the so-called internal interfaces), in this case syntax and the lexicon.
High-current density electron beam generation from a polymer velvet cathode
Authors: Roy Amitava , Menon R , Nagesh K V , Chakravarthy D P
Published: August 2010

Intense electron beam generation studies were carried out using polymer velvet as a cathode material. The typical electron beam parameters were 250 kV, 15 kA, 100 ns, with a few hundred A cm−2 current density. The cathode plasma expansion velocity and the effective initial emission area have been calculated using the perveance data. It was found that the gap closure velocity and the initial emission areas vary randomly on a shot-to-shot basis. In comparison with a graphite cathode, the gap closure velocity of the velvet cathode is less for lower diode gaps, but is much higher for the larger accelerating gaps. One-way analysis of variance was employed to examine the statistical correlation between the diode voltage, current, plasma velocity and the effective emission area for various diode gaps and for two different cathode materials. It was shown that the mean diode voltage, current, plasma velocity and the effective emission area are different for graphite and velvet cathodes whereas the statistical variations of diode voltage and plasma expansion velocities are not cathode material dependent. However, the mean effective emission area is cathode material dependent as are the variances.
Particle in cell modelling of the observed modes of a dc wire discharge
Authors: Gueroult R , Elias P Q , Packan D , Bonnet J , Rax J M
Published: August 2010

Low-pressure dc wire induced plasma sources exhibit two stable modes of discharge—constricted below a threshold pressure and diffuse above. Starting from experimental measurements, we conduct two-dimensional particle in cell (PIC) modelling of a dc low-pressure (10−4–10−2 mbar), low-current (∼1 mA) wire discharge in helium. 2D PIC modelling is required to capture longitudinal non-uniformity of the diffuse mode. PIC simulations reproduce the two discharge modes. The voltage versus pressure curve obtained from simulations matches fairly well the experimental data, including the transition region. Discharge voltage dependence on pressure is analysed in consideration of electron impact ionization rates' evolution with energy. In light of the PIC findings, a model of the discharge mode transition based on the Child–Langmuir theory for ions is proposed. Confrontation with simulated data shows good agreement and validates the model for mode transition prediction. Simulations show that the diffuse mode is a space-charge-dominated regime.
An analysis of corona field charging kinetics for polydisperse aerosol particles by considering concentration and mobility
Authors: Alisoy H Z , Alagoz B B , Alisoy G H
Published: August 2010

In this paper, the kinetics of the charging process of polydisperse aerosol particles in a unipolar corona field is analysed and the effects of the particle concentration and particle mobility on the charging kinetics are investigated theoretically. An equation for time constant is derived to evaluate charging time of the particles.
Hydrogen in polycrystalline ZnO thin films
Authors: Kim W M , Kim Y H , Kim J S , Jeong J , Baik Y-J , Park J-K , Lee K S , Seong T-Y
Published: August 2010

The influence and the states of hydrogen in polycrystalline ZnO thin films were investigated by preparing films with different amounts of oxygen vacancies at various hydrogen potentials. The most notable effect of hydrogen addition was passivation of grain boundaries. The majority of hydrogen incorporation in polycrystalline ZnO films was attributed to hydrogen interstitials, and a substantially smaller number of multicentre bonds at oxygen vacancies were formed even at high hydrogen potentials. The major source of free carriers in polycrystalline ZnO films deposited without intentional hydrogen addition was oxygen vacancies with 2+ charge state with large atomic relaxation.
Arp2/3- and Cofilin-coordinated Actin Dynamics Is Required for Insulin-mediated GLUT4 Translocation to the Surface of Muscle Cells
Authors: Chiu Tim Ting , Patel Nish , Shaw Alisa E. , Bamburg James R. , Klip Amira
Published: August 2010

GLUT4 vesicles are actively recruited to the muscle cell surface upon insulin stimulation. Key to this process is Rac-dependent reorganization of filamentous actin beneath the plasma membrane, but the underlying molecular mechanisms have yet to be elucidated. Using L6 rat skeletal myoblasts stably expressing myc-tagged GLUT4, we found that Arp2/3, acting downstream of Rac GTPase, is responsible for the cortical actin polymerization evoked by insulin. siRNA-mediated silencing of either Arp3 or p34 subunits of the Arp2/3 complex abrogated actin remodeling and impaired GLUT4 translocation. Insulin also led to dephosphorylation of the actin-severing protein cofilin on Ser-3, mediated by the phosphatase slingshot. Cofilin dephosphorylation was prevented by strategies depolymerizing remodeled actin (latrunculin B or p34 silencing), suggesting that accumulation of polymerized actin drives severing to enact a dynamic actin cycling. Cofilin knockdown via siRNA caused overwhelming actin polymerization that subsequently inhibited GLUT4 translocation. This inhibition was relieved by reexpressing Xenopus wild-type cofilin-GFP but not the S3E-cofilin-GFP mutant that emulates permanent phosphorylation. Transferrin recycling was not affected by depleting Arp2/3 or cofilin. These results suggest that cofilin dephosphorylation is required for GLUT4 translocation. We propose that Arp2/3 and cofilin coordinate a dynamic cycle of actin branching and severing at the cell cortex, essential for insulin-mediated GLUT4 translocation in muscle cells.
BioRuby: bioinformatics software for the Ruby programming language
Authors: Goto Naohisa , Prins Pjotr , Nakao Mitsuteru , Bonnal Raoul , Aerts Jan , Katayama Toshiaki
Published: August 2010

Summary: The BioRuby software toolkit contains a comprehensive set of free development tools and libraries for bioinformatics and molecular biology, written in the Ruby programming language. BioRuby has components for sequence analysis, pathway analysis, protein modelling and phylogenetic analysis; it supports many widely used data formats and provides easy access to databases, external programs and public web services, including BLAST, KEGG, GenBank, MEDLINE and GO. BioRuby comes with a tutorial, documentation and an interactive environment, which can be used in the shell, and in the web browser.

Availability: BioRuby is free and open source software, made available under the Ruby license. BioRuby runs on all platforms that support Ruby, including Linux, Mac OS X and Windows. And, with JRuby, BioRuby runs on the Java Virtual Machine. The source code is available from http://www.bioruby.org/.

Contact:  katayama@bioruby.org
Health and age and sex distributions of Baltic grey seals (Halichoerus grypus) collected from bycatch and hunt in the Gulf of Bothnia
Authors: Bäcklin Britt-Marie , Moraeus Charlotta , Roos Anna , Eklöf Eva , Lind Ylva
Published: August 2010

Bäcklin, B-M., Moraeus, C., Roos, A., Eklöf, E., and Lind, Y. 2011. Health and age and sex distributions of Baltic grey seals (Halichoerus grypus) collected from bycatch and hunt in the Gulf of Bothnia. – ICES Journal of Marine Science, 68: 183–188. Age distribution, sex ratio, and season of death were investigated in grey seals taken as bycatch and hunted in the Gulf of Bothnia for the period 2002–2007. In seals 1–20 years old, certain health variables, earlier reported as parts of a disease complex related to persistent organic pollutants, were also investigated. Most of the hunted group were female (60%), but there were more males (62%) in the bycatch group. In spring, there were more bycatch than hunted yearlings. Seals taken as bycatch were leaner than hunted animals, and in hunted seals, there was a significant seasonal difference in blubber thickness that was not observed in seals taken in the bycatch. The prevalence of intestinal ulcers was 18–50% in bycatch and 24–74% in hunted animals. Hunted males 4–20 years old had a significantly greater prevalence of intestinal ulcers than bycatch males in the same age group. Adrenocortical thickening and mean weight of the adrenals increased with age. No lesions were observed in female reproductive organs, and in autumn, nearly all mature females were pregnant. The main differences between hunted and bycatch grey seals were in the season when death occurred, the prevalence of yearlings, the sex ratio, the blubber thickness, and the prevalence of intestinal ulcers.
Influence of Jet Cooking and pH on Extraction and Molecular Weight of β‐Glucan and Arabinoxylan from Barley (Hordeum vulgare Prowashonupana)
Authors: Rose Devin J. , Kim Sanghoon , Inglett George E.
Published: August 2010

Food processing conditions may affect the extractability and molecular weight of β‐glucans and arabinoxylans in cereal products. This can dramatically affect the functional and physiological properties of the final products. Therefore, the purpose of this research was to explore the effects of jet cooking on the content, extractability, and molecular weights of these polymers in barley flour from a high β‐glucan, waxy barley genotype, Prowashonupana. Barley flours were jet cooked without pH adjustment or after adjusting to pH 7, 9, or 11. Jet cooking without pH adjustment increased the extractability of β‐glucans from 15.4 to 38.0% when extracted with water at 30°C. As pH during jet cooking increased, the extractability further increased to 63.5% at pH 11. Arabinoxylan extractability was only substantially affected when the pH of jet cooking was alkaline (extractability increased from 11.4 to 48.5% when jet cooked at pH 11). Jet cooking without pH adjustment resulted in slight increases in peak molecular weights for both polymers (β‐glucan increased from 420,000 to 443,000; arabinoxylan increased from 119,000 to 125,000); higher pH values during jet cooking resulted in minor decrease in molecular weights.
Molecular Weight Distribution of Proteins in Hard Red Spring Wheat: Relationship to Quality Parameters and Intrasample Uniformity
Authors: Ohm Jae‐Bom , Hareland Gary , Simsek Senay , Seabourn Bradford , Maghirang Elizabeth , Dowell Floyd
Published: August 2010

Molecular weight distribution (MWD) of proteins extracted from hard red spring wheat was analyzed by size‐exclusion HPLC to investigate associations with wheat and breadmaking quality characteristics. Certain protein fractions were related to associations between wheat and breadmaking parameters, specifically when effect of quantitative variation of protein on those parameters was statistically eliminated by partial correlation analysis. SDS‐unextractable high molecular weight polymeric proteins had positive partial correlations with percent vitreous kernel content and breadmaking parameters, including mix time and bread loaf volume. SDS‐extractable protein fractions that were eluted before the primary gliadin peak had positive partial correlations with kernel hardness and water absorption parameters. The proportion of main gliadin fractions in total protein had a negative partial correlation with bread loaf volume and positive correlations with kernel hardness and water absorption parameters. Intrasample uniformity in protein MWD and kernel characteristics was estimated from three kernel subsamples that were separated according to single kernel protein content within individual wheat samples by a single‐kernel near‐infrared sorter. Wheat subsamples were significantly different in protein MWD. Intrasample uniformity in protein MWD did not differ greatly among wheat samples.
A Novel Transcriptional Factor Important for Pathogenesis and Ascosporogenesis in Fusarium graminearum
Authors: Wang Yang , Liu Wende , Hou Zhanming , Wang Chenfang , Zhou Xiaoying , Jonkers Wilfried , Ding Shengli , Kistler H. Corby , Xu Jin-Rong
Published: August 2010

Fusarium head blight or scab caused by Fusarium graminearum is an important disease of wheat and barley. The pathogen not only causes severe yield losses but also contaminates infested grains with mycotoxins. In a previous study, we identified several pathogenicity mutants by random insertional mutagenesis. One of these mutants was disrupted in the ZIF1 gene, which encodes a b-ZIP transcription factor unique to filamentous ascomycetes. The Δzif1 mutant generated by gene replacement was significantly reduced in deoxynivalenol (DON) production and virulence on flowering wheat heads. It was defective in spreading from inoculated florets to the rachis and other spikelets. Deletion of the ZIF1 ortholog MoZIF1 in the rice blast fungus also caused reductions in virulence and in invasive growth. In addition, the Δzif1 mutant is defective in sexual reproduction. Although it had normal male fertility, when selfed or mated as the female in outcrosess, the Δzif1 mutant produced small, pigmented perithecia that were sterile (lack of asci and ascospores), suggesting a female-specific role for ZIF1 during fertilization or ascus development. Similar female-specific defects in sexual reproduction were observed in the ΔMozif1 mutant. When mated as the female, the ΔMozif1 perithecia failed to develop long necks and asci or ascospores. The ZIF1 gene is well conserved in filamentous ascomycetes, particularly in the b-ZIP domain, which is essential for its function. Expression of ZIF1 in Magnaporthe oryzae complemented the defects of the ΔMozif1 mutant. These results indicate that this b-ZIP transcription factor is functionally conserved in these two fungal pathogens for plant infection and sexual reproduction.
Effect of Temperature on Conidial Germination ofBotryosphaeriaceaeSpecies Infecting Grapevines
Authors: Úrbez-Torres José R. , Bruez Emilie , Hurtado José , Gubler Walter D.
Published: August 2010

Germination of conidia of eight botryosphaeriaceous fungi infecting grapevines was evaluated after 2, 4, 6, 12, and 24 h incubation under eight different temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C). The effect of temperature on conidial germination was also evaluated in different stages (hyaline versus pigmented conidia) of the species Lasiodiplodia theobromae. Conidial germination of Botryosphaeriaceae species infecting grapevines was significantly affected by temperature. Overall, conidial germination increased significantly with longer incubation times, especially from 2 to 12 h. In most cases, germination of conidia was not significantly different between 12 and 24 h incubation. Conidia of botryosphaeriaceous species did not germinate (with the exception of Botryosphaeria dothidea and Neofusicoccum parvum) at 5°C, and only B. dothidea, Diplodia seriata, and L. theobromae showed high levels of conidial germination at 40°C. Optimum conidial germination temperatures (defined as the temperature in which germination reached at least 50% in the shortest incubation time) were 25°C for B. dothidea and Dothiorella iberica, 25 to 30°C for Spencermartinsia viticola, 30°C for Diplodia corticola, D. mutila, D. seriata, N. parvum, and hyaline L. theobromae, and 40°C for pigmented L. theobromae conidia. Successful conidial germination of species of Botryosphaeriaceae infecting grapevines was always observed between 10 and 35°C with the exception of Dothiorella iberica and pigmented L. theobromae conidia, neither of which germinated at 35 and 10°C, respectively. Results of this study show conidia of botryosphaeriaceous species infecting grapevines to be capable of germination under a broad range of temperatures including those considered to be extreme, which may explain the success of these species as grapevine pathogens throughout most of the grape-growing areas in both Northern and Southern Hemispheres.
Bacterial Wilt Resistance in Tomato, Pepper, and Eggplant: Genetic Resources Respond to Diverse Strains in the Ralstonia solanacearum Species Complex
Authors: Lebeau A. , Daunay M.-C. , Frary A. , Palloix A. , Wang J.-F. , Dintinger J. , Chiroleu F. , Wicker E. , Prior P.
Published: August 2010

Bacterial wilt, caused by strains belonging to the Ralstonia solanacearum species complex, inflicts severe economic losses in many crops worldwide. Host resistance remains the most effective control strategy against this disease. However, wilt resistance is often overcome due to the considerable variation among pathogen strains. To help breeders circumvent this problem, we assembled a worldwide collection of 30 accessions of tomato, eggplant and pepper (Core-TEP), most of which are commonly used as sources of resistance to R. solanacearum or for mapping quantitative trait loci. The Core-TEP lines were challenged with a core collection of 12 pathogen strains (Core-Rs2) representing the phylogenetic diversity of R. solanacearum. We observed six interaction phenotypes, from highly susceptible to highly resistant. Intermediate phenotypes resulted from the plants' ability to tolerate latent infections (i.e., bacterial colonization of vascular elements with limited or no wilting). The Core-Rs2 strains partitioned into three pathotypes on pepper accessions, five on tomato, and six on eggplant. A “pathoprofile” concept was developed to characterize the strain clusters, which displayed six virulence patterns on the whole set of Core-TEP host accessions. Neither pathotypes nor pathoprofiles were phylotype specific. Pathoprofiles with high aggressiveness were mainly found in strains from phylotypes I, IIB, and III. One pathoprofile included a strain that overcame almost all resistance sources.
Hepatic coenzyme Q redox balance of fishes as a potential bioindicator of environmental contamination by polycyclic aromatic hydrocarbons
Authors: Hasbi Ghitarina , de Nys Rocky , Burns Kathryn , Whalan Steve , Dunlap Walter C.
Published: August 2010

In this communication, we introduce a novel biomarker of aquatic contamination based on the xenobiotic-induced response of the hepatic coenzyme Q (CoQ) redox balance of fishes to polycyclic aromatic hydrocarbons (PAHs). The method is demonstrated by comparing changes in the liver CoQ redox balance with that measured using the CYP1A-based, 7-ethoxyresofurin-O-deethylase activity assay, on administration of benzo[a]pyrene (BaP) and β-naphthoflavone (BNF) to Barramundi (
Lates calcarifer
). Both assays showed comparable dose-dependent effects in fish treated with BaP or BNF. Perturbation in the constitutive hepatic CoQ redox balance of fishes may thus provide a simple biomarker of aquatic PAH contamination.
Biological characteristics of stem cells from foetal, cord blood and extraembryonic tissues
Authors: Abdulrazzak Hassan , Moschidou Dafni , Jones Gemma , Guillot Pascale V.
Published: August 2010

Foetal stem cells (FSCs) can be isolated during gestation from many different tissues such as blood, liver and bone marrow as well as from a variety of extraembryonic tissues such as amniotic fluid and placenta. Strong evidence suggests that these cells differ on many biological aspects such as growth kinetics, morphology, immunophenotype, differentiation potential and engraftment capacityin vivo. Despite these differences, FSCs appear to be more primitive and have greater multi-potentiality than their adult counterparts. For example, foetal blood haemopoietic stem cells proliferate more rapidly than those found in cord blood or adult bone marrow. These features have led to FSCs being investigated for pre- and post-natal cell therapy and regenerative medicine applications. The cells have been used in pre-clinical studies to treat a wide range of diseases such as skeletal dysplasia, diaphragmatic hernia and respiratory failure, white matter damage, renal pathologies as well as cancers. Their intermediate state between adult and embryonic stem cells also makes them an ideal candidate for reprogramming to the pluripotent status.
Minimal energy for elastic inclusions
Authors: Knüpfer Hans , Kohn Robert V.
Published: August 2010

We consider a variant of the isoperimetric problem with a non-local term representing elastic energy. More precisely, our aim is to analyse the optimal energy of an inclusion of a fixed volume the energy of which is determined by surface and elastic energies. This problem has been studied extensively in the physical/metallurgical literature; however, the analysis has mainly been either (i) numerical, or (ii) restricted to a specific set of inclusion shapes, e.g. ellipsoids. In this article, we prove a lower bound for the energy, with noa priorihypothesis on the shape (or even number) of the inclusions.
Grandmothering and natural selection
Authors: Kachel A. Friederike , Premo L. S. , Hublin Jean-Jacques
Published: August 2010

Humans are unique among primates in that women regularly outlive their reproductive period by decades. The grandmother hypothesis proposes that natural selection increased the length of the human post-menopausal period—and, thus, extended longevity—as a result of the inclusive fitness benefits of grandmothering. However, it has yet to be demonstrated that the inclusive fitness benefits associated with grandmothering are large enough to warrant this explanation. Here, we show that the inclusive fitness benefits are too small to affect the evolution of longevity under a wide range of conditions in simulated populations. This is due in large part to the relatively weak selection that applies to women near or beyond the end of their reproductive period. However, we find that grandmothers can facilitate the evolution of a shorter reproductive period when their help decreases the weaning age of their matrilineal grandchildren. Because selection favours a shorter reproductive period in the presence of shorter interbirth intervals, this finding holds true for any form of allocare that helps mothers resume cycling more quickly. We conclude that while grandmothering is unlikely to explain human-like longevity, allocare could have played an important role in shaping other unique aspects of human life history, such as a later age at first birth and a shorter female reproductive period.
SHORT-ROOT and SCARECROW Regulate Leaf Growth in Arabidopsis by Stimulating S-Phase Progression of the Cell Cycle
Authors: Dhondt Stijn , Coppens Frederik , De Winter Freya , Swarup Kamal , Merks Roeland M.H. , Inzé Dirk , Bennett Malcolm J. , Beemster Gerrit T.S.
Published: August 2010

SHORT-ROOT (SHR) and SCARECROW (SCR) are required for stem cell maintenance in the Arabidopsis (Arabidopsis thaliana) root meristem, ensuring its indeterminate growth. Mutation of SHR and SCR genes results in disorganization of the quiescent center and loss of stem cell activity, resulting in the cessation of root growth. This paper reports on the role of SHR and SCR in the development of leaves, which, in contrast to the root, have a determinate growth pattern and lack a persistent stem cell niche. Our results demonstrate that inhibition of leaf growth in shr and scr mutants is not a secondary effect of the compromised root development but is caused by an effect on cell division in the leaves: a reduced cell division rate and early exit of the proliferation phase. Consistent with the observed cell division phenotype, the expression of SHR and SCR genes in leaves is closely associated with cell division activity in most cell types. The increased cell cycle duration is due to a prolonged S-phase duration, which is mediated by up-regulation of cell cycle inhibitors known to restrain the activity of the transcription factor, E2Fa. Therefore, we conclude that, in contrast to their specific roles in cortex/endodermis differentiation and stem cell maintenance in the root, SHR and SCR primarily function as general regulators of cell proliferation in leaves.
Plant Cell Growth in Tissue
Authors: Ortega Joseph K.E.
Published: August 2010

Cell walls are part of the apoplasm pathway that transports water, solutes, and nutrients to cells within plant tissue. Pressures within the apoplasm (cell walls and xylem) are often different from atmospheric pressure during expansive growth of plant cells in tissue. The previously established Augmented Growth Equations are modified to evaluate the turgor pressure, water uptake, and expansive growth of plant cells in tissue when pressures within the apoplasm are lower and higher than atmospheric pressure. Analyses indicate that a step-down and step-up in pressure within the apoplasm will cause an exponential decrease and increase in turgor pressure, respectively, and the rates of water uptake and expansive growth each undergo a rapid decrease and increase, respectively, followed by an exponential return to their initial magnitude. Other analyses indicate that pressure within the apoplasm decreases exponentially to a lower value after a step-down in turgor pressure, which simulates its behavior after an increase in expansive growth rate. Also, analyses indicate that the turgor pressure decays exponentially to a constant value that is the sum of the critical turgor pressure and pressure within the apoplasm during stress relaxation experiments in which pressures within the apoplasm are not atmospheric pressure. Additional analyses indicate that when the turgor pressure is constant (clamped), a decrease in pressure within the apoplasm elicits an increase in elastic expansion followed by an increase in irreversible expansion rate. Some analytical results are supported by prior experimental research, and other analytical results can be verified with existing experimental methods.
Viewpoint: Sustainability: Malthus revisited?
Authors: Brander James A.
Published: August 2010

Abstract. The sustainability debate concerns whether the world will experience stable or improving living standards for the foreseeable future, or whether the current trajectory will overtax the natural environment, leading to a ‘crash’ in living standards. This paper selectively reviews relevant research, focusing on both ecological concerns and technological progress, and asks whether sustainability would be problematic without rapid population growth. I suggest that continued demographic transition to lower fertility is the primary requirement for achieving sustainable development. This is, effectively, a modern translation ofMalthus (1798). The paper also discusses the role of the Malthusian cycle in human evolution.
Do state borders matter for U.S. intranational trade? The role of history and internal migration
Authors: Millimet Daniel L. , Osang Thomas
Published: August 2010

Abstract.  Empirical evidence of the impact of borders on international trade flows using the gravity equation approach abounds. This paper examines the empirical relevance of state borders in U.S. interstate trade for various specifications of the gravity equation. We find a large and economically significant subnational border effect for some specifications. However, two model specifications drastically reduce (if not eliminate) the border effect: (i) dynamic panel specifications controlling for past levels of trade and (ii) models conditioning on internal migration.
Exchanging market access at the outsiders' expense: the case of customs unions
Authors: Ornelas Emanuel
Published: August 2010

Abstract.  Under a customs union, countries can exchange preferential market access by coordinating external tariffs to shift profits from excluded countries. I show that the exporting rents resulting from this coordination can offset trade diversion losses produced by the union, even if its members are relatively small in world markets. Such gains come, however, at the expense of excluded countries. I show that small countries can use customs unions also to foster multilateral cooperation, by increasing the incentives of excluded countries to support global free trade.
Return policies, market outcomes, and consumer welfare
Authors: Chesnokova Tatyana
Published: August 2010

Abstract.  The effect of return policies on market outcomes is studied in a model where consumers differ in their valuations of time. Product reliability is identified with defect rates. Producers first choose reliability levels and then compete in prices. For given defect rates, allowing returns makes products closer substitutes, enhancing competition and reducing prices. Being closer substitutes makes higher reliability less worthwhile, which reduces reliability. While the decrease in reliability reduces consumer welfare, the decrease in prices raises it. The latter dominates, so that aggregate consumer welfare increases with return policy.
Viewpoint: On the generalizability of lab behaviour to the field
Authors: Levitt Steven D. , List John A.
Published: August 2010

Abstract.  We can think of no question more fundamental to experimental economics than understanding whether, and under what circumstances, laboratory results generalize to naturally occurring environments. In this paper, we extend Levitt and List (2006) to the class of games in which financial payoffs and ‘doing the right thing’ are not necessarily in conflict. We argue that behaviour is crucially linked to not only the preferences of people, but also the properties of the situation. By doing so, we are able to provide a road map of the psychological and economic properties of people and situations that might interfere with generalizability of laboratory result from a broad class of games.
Investment‐specific shocks and external balances in a small open economy model
Authors: Letendre Marc‐André , Luo Daqing
Published: August 2010

Abstract.  We set up a standard small open economy business cycle model driven by government spending shocks, neutral productivity (TFP) shocks, and investment‐specific shocks. The model is calibrated to quarterly Canadian data and its predicted moments and sample paths are compared with their Canadian counterparts. We find that the model captures the dynamics in investment and in the trade balance better than special cases of the model where either one of the productivity shocks is omitted. More specifically, the model matches the variance of the trade balance‐output ratio, its correlation with output and its autocorrelation. It also matches the output‐investment correlation.
A spatial analysis of provincial corporate income tax responses: evidence from Canada
Authors: Karkalakos Sotiris , Kotsogiannis Christos
Published: August 2010

Abstract. Using a model of interdependent tax choices, and accounting for equalization entitlements and general transfers, this paper estimates – making use of a spatial econometric framework – corporate income tax‐setting functions forallCanadian provincial governments. The results show that there is a statistically significant positive fiscal interaction among a subset of provinces and between all provinces and the federal government. Provincial corporate income taxes are also found to be negatively related to equalization entitlements, general federal transfers, and the federal corporate income tax. A robustness check on the fiscal relationship between Ontario and Quebec verifies the existence of significant bi‐directional fiscal interdependencies. The paper also introduces U.S state corporate income taxes as covariates and examines their interaction with Canadian provinces.
Forecast content and content horizons for some important macroeconomic time series
Authors: Galbraith John W. , Tkacz Greg
Published: August 2010

Abstract.  The information content of statistical forecasts of approximately stationary quantities tends to decline as the forecast horizon increases, and there exists a maximum horizon beyond which forecasts cannot provide discernibly more information about the variable than is present in the unconditional mean (the content horizon). The pattern of decay of forecast content (or skill) with increasing horizon is well known for many types of meteorological forecasts; by contrast, little generally accepted information about these patterns or content horizons is available for economic variables. In this paper we estimate content horizons for a variety of macroeconomic quantities; more generally, we characterize the pattern of decay of forecast content as we project farther into the future. We find a wide variety of results for the different macroeconomic quantities, with models for some quantities providing useful content several years into the future, for other quantities providing negligible content beyond one or two months or quarters.