bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study of homogeneous nucleation from the bismuth supersaturated vapor: Evaluation of the surface tension of critical nucleus
Authors: Onischuk A. A. , Vosel S. V. , Borovkova O. V. , Baklanov A. M. , Karasev V. V. , di Stasio S.
Published: June 2012

The homogeneous nucleation of bismuth supersaturated vapor is studied in a laminar flow quartz tube nucleation chamber. The concentration, size, and morphology of outcoming aerosol particles are analyzed by a transmission electron microscope (TEM) and an automatic diffusion battery (ADB). The wall deposit morphology is studied by scanning electron microscopy. The rate of wall deposition is measured by the light absorption technique and direct weighting of the wall deposits. The confines of the nucleation region are determined in the “supersaturation cut-off” measurements inserting a metal grid into the nucleation zone and monitoring the outlet aerosol concentration response. Using the above experimental techniques, the nucleation rate, supersaturation, and nucleation temperature are measured. The surface tension of the critical nucleus and the radius of the surface of tension are determined from the measured nucleation parameters. To this aim an analytical formula for the nucleation rate is used, derived from author's previous papers based on the Gibbs formula for the work of formation of critical nucleus and the translation-rotation correction. A more accurate approach is also applied to determine the surface tension of critical drop from the experimentally measured bismuth mass flow, temperature profiles, ADB, and TEM data solving an inverse problem by numerical simulation. The simulation of the vapor to particles conversion is carried out in the framework of the explicit finite difference scheme accounting the nucleation, vapor to particles and vapor to wall deposition, and particle to wall deposition, coagulation. The nucleation rate is determined from simulations to be in the range of 109–1011 cm−3 s−1 for the supersaturation of Bi2 dimers being 1017–107 and the nucleation temperature 330–570 K, respectively. The surface tension σS of the bismuth critical nucleus is found to be in the range of 455–487 mN/m for the radius of the surface of tension from 0.36 to 0.48 nm. The function σS changes weakly with the radius of critical nucleus. The value of σS is from 14% to 24% higher than the surface tension of a flat surface.
On the Curie temperature dependency of the magnetocaloric effect
Authors: Belo J. H. , Amaral J. S. , Pereira A. M. , Amaral V. S. , Araújo J. P.
Published: June 2012

We investigate the magnetocaloric effect dependency on the most important microscopic parameters of ferromagnetic materials, such as the Curie temperature (TC), the spin value (J), and the magnetic field change (ΔH). Second- and first-order phase transition systems are considered, using the Bean-Rodbell model [C. P. Bean and D. S. Rodbell, Phys. Rev. 126, 104 (1962)] of magnetovolume interactions on the Weiss mean-field model [P. Weiss, J. Phys. Theory Appl. 6, 661 (1907)]. The magnetocaloric effect simulations show a surprising TC−2/3 linear dependence of the maximum entropy change (ΔSmmax), which is observed for all simulated systems. An approximate state equation establishing the dependence of ΔSmmax on TC, ΔH, J, and the magnetic atoms density (N) is presented. The dependence of maximum magnetic entropy change on TC−2/3 is validated by a wide set of experimental results of second- and first-order phase transition materials that are promising for magnetic refrigeration applications at room temperature.
AsH3 ultraviolet photochemistry: An ab initio view
Authors: Alekseyev Aleksey B. , Buenker Robert J. , Liebermann Heinz–Peter
Published: June 2012

Multireference configuration interaction calculations have been carried out for low-lying electronic states of AsH3. Bending potentials for the nine lowest states of AsH3 are obtained in C3v symmetry for As–H distances fixed at the ground state equilibrium value of 2.850 a0, as well as for the minimum energy path constrained to R1 = R2 = R3. The calculated equilibrium geometry and bond energy for the \documentclass[12pt]{minimal}\begin{document}$\tilde{X}\,{^1}{\!A}_{1}$\end{document}X̃A11 ground state agree very well with the previous experimental and theoretical data. It is shown that the lowest excited singlet state belongs to the 1A1 symmetry (in C3v), in contradiction to the previous calculations. This state is characterized by a planar equilibrium geometry. Asymmetric stretch potential energy surface (PES) cuts along the H2As–H recoil coordinate (at R1 = R2 = 2.850 a0, θ = 123.9° and 90°) for numerous excited states and two-dimensional PESs for the \documentclass[12pt]{minimal}\begin{document}$\tilde{X}$\end{document}X̃ and \documentclass[12pt]{minimal}\begin{document}$\tilde{A}$\end{document}Ã states up to the dissociation limits are obtained for the first time. The \documentclass[12pt]{minimal}\begin{document}$\tilde{A}\,{^1}{\!A}_{1}, \tilde{B}\,^1E - \tilde{X}\,{^1}{\!A}_{1}$\end{document}ÃA11,B̃E1−X̃A11 transition moments are calculated as well and used together with the PES data for the analysis of possible photodecay channels of arsine in its first absorption band.
Nonstandard cages in the formation process of methane clathrate: Stability, structure, and spectroscopic implications from first-principles
Authors: Tang Lingli , Su Yan , Liu Yuan , Zhao Jijun , Qiu Ruifeng
Published: June 2012

Endohedral CH4@(H2O)n (n = 16, 18, 20, 22, 24) clusters with standard and nonstandard cage configurations containing four-, five-, six-, seven-membered rings were generated by spiral algorithm and were systematically explored using DFT-D methods. The geometries of all isomers were optimized in vacuum and aqueous solution. In vacuum, encapsulation of methane molecules can stabilize the hollow (H2O)n cage by 2.31∼5.44 kcal/mol; but the endohedral CH4@(H2O)n cages are still less stable than the pure (H2O)n clusters. Aqueous environment could promote the stabilities of the hollow (H2O)n cages as well as the CH4@(H2O)n clusters, and the CH4@(H2O)n clusters possess larger stabilization energies with regard to the pure (H2O)n clusters except for n = 24. The lowest energy structures of the CH4@(H2O)20 and CH4@(H2O)24 cages are identical to the building units in the crystalline sI clathrate hydrate. All of the low-energy cages (including both regular and irregular ones) have large structural similarity and can be connected by “dimer-insertion” operation and Stone-Wales transformation. Our calculation also showed that in the range of cluster size n = 16–24, the relative energies of cage isomers tend to decrease with increasing number of the adjacent pentagons in the oxygen skeleton structures. In addition to the regular endohedral CH4@(H2O)20 and CH4@(H2O)24 cage structures, some nonstandard CH4@(H2O)n (n = 18, 20, 22, 24) cages have lower energies and might appear during nucleation process of methane hydrate. For the methane molecules in these low-energy cage isomers, we found that the C–H symmetric stretching frequencies show a red-shift trend and the 13C NMR chemical shifts generally move toward negative values as the cavity size increases. These theoretical results are comparable to the available experimental data and might help experimental identification of the endohedral water cages during nucleation.
Thermodynamic instability of ZnSe/ZnS core/shell quantum dots
Authors: Pandey Sumeet C. , Wang Jun , Mountziaris T. J. , Maroudas Dimitrios
Published: June 2012

We investigate the stability of ZnSe/ZnS core/shell quantum dots (QDs) based on density-functional-theory (DFT) calculations combined with photoluminescence (PL) and x-ray photoelectron (XPS) spectroscopy of as-synthesized and annealed QDs. The results demonstrate that core/shell interfaces in ZnSe/ZnS QDs are thermodynamically unstable. Under low-temperature annealing, the intermixing of S and Se atoms leads to alloying of the pure ZnSe core and ZnS shells. Upon high-temperature annealing, the degradation of the PL properties of the QDs also is observed.
A new type of optical biosensor from DNA wrapped semiconductor graphene ribbons
Authors: Phan Anh D. , Viet N. A.
Published: June 2012

Based on a model of the optical biosensors [Heller et al., Science 311, 508 (2006)] by wrapping a piece of double-stranded DNA around the surface of single-walled carbon nanotubes (SWCNTs), we propose a new design model of this sensor, in which the SWCNT is replaced by a semiconductor graphene ribbon (SGR). Using a simple theory of exciton in SGRs, we investigated transition of DNA secondary structure from the native, right-handed B form to the alternate, left-handed Z form. This structural phase transition of DNA is the working principle of this optical biosensor at the sub cellular level from DNA and semiconductor graphene ribbons.
Polymers as compressible soft spheres
Authors: D'Adamo Giuseppe , Pelissetto Andrea , Pierleoni Carlo
Published: June 2012

We consider a coarse-grained model in which polymers under good-solvent conditions are represented by soft spheres whose radii, which should be identified with the polymer radii of gyrations, are allowed to fluctuate. The corresponding pair potential depends on the sphere radii. This model is a single-sphere version of the one proposed in Vettorel et al. [Soft Matter 6, 2282 (2010)]10.1039/b921159d, and it is sufficiently simple to allow us to determine all potentials accurately from full-monomer simulations of two isolated polymers (zero-density potentials). We find that in the dilute regime (which is the expected validity range of single-sphere coarse-grained models based on zero-density potentials) this model correctly reproduces the density dependence of the radius of gyration. However, for the thermodynamics and the intermolecular structure, the model is largely equivalent to the simpler one in which the sphere radii are fixed to the average value of the radius of gyration and radii-independent potentials are used: for the thermodynamics there is no advantage in considering a fluctuating sphere size.
Electrical growth of metallic nanoparticles in mesoporous silica films using atomic force microscopy
Authors: Hubert Christophe , Amrani Hamza , Ali Khan Murtaza , Vocanson Francis , Destouches Nathalie
Published: June 2012

We report the formation of silver nanoparticles in mesoporous silica films under a polarized micro-tip. By applying a bias voltage between an atomic force microscope conductive tip and an indium tin oxide substrate, reduction of silver ions initially impregnated in a mesoporous silica film occurs and leads to the creation of silver nanoparticles. This technique allows both the precise positioning of the nanoparticles via the control of the tip position and the control of the nanoparticles size by varying the bias voltage applied to the tip or the contact time.
Tunable misalignment of ferromagnetic and antiferromagnetic easy axes in exchange biased bilayers
Authors: Rodríguez-Suárez R. L. , Vilela-Leão L. H. , Bueno T. , Mendes J. B. S. , Landeros P. , Rezende S. M. , Azevedo A.
Published: June 2012

In this paper we report experiments that show how to tune the unidirectional anisotropy field in exchange biased Ni81Fe19/Ir20Mn80 bilayers grown by sputtering. During growth the samples are held in an obliquely inclined stage, and simultaneously a static magnetic field is applied along an arbitrary direction in the film plane. While the direction of the ferromagnetic anisotropy field is given by the tilted columnar microstructures induced by the oblique sputtering, the direction of the unidirectional field can be tuned by the application of the in situ magnetic field. The magnetic properties were investigated using the ferromagnetic resonance technique.
Normal or inverse magnetocaloric effects at the transition between antiferromagnetism and ferromagnetism
Authors: Li Bing , Liang Wen , Ren Weijun , Hu Weijin , Li Ji , Jin Changqing , Zhang Zhidong
Published: June 2012

The magnetocaloric effect (MCE) at the antiferromagnetic (AF) to ferromagnetic (F) phase transition in Mn1.05Ni0.85Ge and CrO1.86F0.14, and the MCE at the F-AF transition in Tb3Co have been investigated. Mn1.05Ni0.85Ge and CrO1.86F0.14 are found to exhibit the inverse MCE whereas the MCE of Tb3Co is normal. For these compounds, the dependence of the transition temperature on the applied magnetic field B has been studied. A thermodynamical analysis is presented of the sign of the magnetic-entropy change in these three compounds which are representatives of two different types of B-T diagrams. Other possible B-T diagrams are discussed and the analysis is extended to AF-F and F-AF phase transitions reported in literature.
Terahertz Faraday rotation in a magnetic liquid: High magneto-optical figure of merit and broadband operation in a ferrofluid
Authors: Shalaby Mostafa , Peccianti Marco , Ozturk Yavuz , Clerici Matteo , Al-Naib Ibraheem , Razzari Luca , Ozaki Tsuneyuki , Mazhorova Anna , Skorobogatiy Maksim , Morandotti Roberto
Published: June 2012

We report on the demonstration of a high figure of merit (FOM) Faraday rotation in a liquid in the terahertz (THz) regime. Using a ferrofluid, a high broadband rotation (11 mrad/mm) is experimentally demonstrated in the frequency range of 0.2–0.9 THz at room temperature. Given the low absorption of the liquid, a high magneto-optical figure of merit (5-16 rad.cm/T) is obtained.
Quasi-millimeter-wave absorption behavior in Y/Yb-stabilized zirconia ceramics
Authors: Teranishi Takashi , Akiyama Naoki , Ayano Keiko , Hayashi Hidetaka , Kishimoto Akira , Fujimori Kazuhiro , Hoshina Takuya , Takeda Hiroaki , Tsurumi Takaaki
Published: June 2012

Broadband dielectric spectra from 10 to 1014 Hz were acquired for 8 mol. % Y2O3/Yb2O3-stabilized zirconia (8YSZ and 8YbSZ) ceramics that related the dipole and ionic polarization losses to the absorption efficiency of electromagnetic irradiation. For 24 GHz irradiation, 8YSZ exhibited a higher absorption efficiency than 8YbSZ, resulting in a higher dielectric loss. The difference in the dielectric loss was interpreted as the difference in the loss of the dipoles originating from the fluctuations in the defect associations (Y′ZrVo¨ and Yb′ZrVo¨).
Lasing of extreme ultraviolet light with nitrogen plasma in a recombining phase—Roles of doubly excited states
Authors: Ozawa Takuya , Yamamura Shuhei , Tatsumura Nao , Horioka Kazuhiko , Kawamura Tohru
Published: June 2012

Focused are the properties of population inversion with nitrogen plasma between n = 3 and 2 of a hydrogen-like state in a recombining phase. The population inversion is calculated in the framework of population kinetics, and the gain coefficient G is estimated. The maximum plasma length L is approximated by a product of the duration of population inversion τe and the speed of light c. In the calculation, dielectronic-capture ladderlike (DL) processes are considered. At the plasma ion densities of 1017–18 cm−3 with a rapid cooling, the DL deexcitations make a large contribution to the population inversion, resulting in GL=5–10, and the prescription of plasma cooling is found to be definitely critical.
Combined plasmonic and dielectric rear reflectors for enhanced photocurrent in solar cells
Authors: Basch A. , Beck F. J. , Söderström T. , Varlamov S. , Catchpole K. R.
Published: June 2012

A doubling of the photocurrent due to light trapping is demonstrated by the combination of silver nanoparticles with a highly reflective back scatterer fabricated by Snow Globe Coating on the rear of a 2 μm polycrystalline silicon thin film solar cell. The binder free high refractive index titania particles can overcome light losses due to transmission. Modelling indicates that adding plasmonic nanoparticles to the back scatterer widens the angular distribution of scattered light such that over 80% of long wavelength light is scattered outside the Si/air loss cone and trapped in the cell, compared to 30% for the titania alone.
Effect of the energy dependence of the carrier scattering time on the thermoelectric power factor of quantum wells and nanowires
Authors: Cornett Jane E. , Rabin Oded
Published: June 2012

The size-dependence of the thermoelectric power factor of thin-films and nanowires is theoretically investigated from the electric quantum limit (EQL) to the bulk-like regime. Different functional forms of the energy-dependent relaxation time τ(E) are incorporated in the model to account for carrier scattering mechanisms typical in semiconductor nanostructures. The calculations show that the steeper the increase in the relaxation time with carrier energy, the higher the power factor-to-average scattering time ratio, PF/〈τ〉, confirming the benefits of the preferential scattering of low-energy carriers to thermoelectric performance. However, outside the EQL, the power factor values are lower in the low-dimensional structures than in their three-dimensional counterparts. Thus, the power factor is more readily improved by modifications of the scattering rates than by quantization of the energy states.
Ultrafast carrier dynamics and radiative recombination in multiferroic BiFeO3
Authors: Sheu Y. M. , Trugman S. A. , Park Y.-S. , Lee S. , Yi H. T. , Cheong S.-W. , Jia Q. X. , Taylor A. J. , Prasankumar R. P.
Published: June 2012

We report a comprehensive study of ultrafast carrier dynamics in single crystals of multiferroic BiFeO3. Using degenerate femtosecond optical pump-probe spectroscopy, we find that the photoexcited electrons relax to the conduction band minimum through electron-phonon coupling with a ∼1 ps time constant that does not significantly change across the antiferromagnetic transition. Electrons subsequently leave the conduction band and primarily decay via radiative recombination on a nanosecond timescale, as supported by photoluminescence measurements. We find that despite the coexisting ferroelectric and antiferromagnetic orders in BiFeO3, its intrinsic nature results in carrier relaxation similar to that observed in bulk semiconductors.
Age, growth and maturity of the brown stingray (Dasyatis lata) around Oahu, Hawai'i
Authors: Dale J. J. , Holland K. N.
Published: June 2012

Baseline data on life-history characteristics of elasmobranchs are often lacking before fisheries exploitation, hindering successful management and conservation of affected species. Age, growth and maturity estimates were determined for the brown stingray, Dasyatis lata, an abundant benthic predator in Hawai’i’s coastal ecosystems, from an unfished population off Oahu, Hawai’i. Age estimates ranged from 0 to 28 years for females and from 0 to 25 years for males. Annual growth-band deposition was verified through marginal increment and centrum edge analysis, as well as recapture of two stingrays marked with oxytetracycline. Multiple growth models were fitted to disk width (DW) and weight-at-age data and evaluated for biological realism and statistical fit. Logistic growth functions best described growth of male and female stingrays, whereas no support was found for von Bertalanffy growth models. Females attained larger sizes (L∞) and exhibited lower growth coefficients (k) than did males. Median size and age at first maturity was estimated to be 104.9 cm DW (15 years) for females and 74.9 cm DW (8.3 years) for males. These life-history characteristics highlight the importance of obtaining baseline data before fisheries are established and indicate that any fishery for brown stingrays should be managed using conservative management strategies.
Phase transitions in physiologic coupling
Authors: Bartsch Ronny P. , Schumann Aicko Y. , Kantelhardt Jan W. , Penzel Thomas , Ivanov Plamen Ch.
Published: June 2012

Integrated physiological systems, such as the cardiac and the respiratory system, exhibit complex dynamics that are further influenced by intrinsic feedback mechanisms controlling their interaction. To probe how the cardiac and the respiratory system adjust their rhythms, despite continuous fluctuations in their dynamics, we study the phase synchronization of heartbeat intervals and respiratory cycles. The nature of this interaction, its physiological and clinical relevance, and its relation to mechanisms of neural control is not well understood. We investigate whether and how cardiorespiratory phase synchronization (CRPS) responds to changes in physiological states and conditions. We find that the degree of CRPS in healthy subjects dramatically changes with sleep-stage transitions and exhibits a pronounced stratification pattern with a 400% increase from rapid eye movement sleep and wake, to light and deep sleep, indicating that sympatho-vagal balance strongly influences CRPS. For elderly subjects, we find that the overall degree of CRPS is reduced by approximately 40%, which has important clinical implications. However, the sleep-stage stratification pattern we uncover in CRPS does not break down with advanced age, and surprisingly, remains stable across subjects. Our results show that the difference in CRPS between sleep stages exceeds the difference between young and elderly, suggesting that sleep regulation has a significantly stronger effect on cardiorespiratory coupling than healthy aging. We demonstrate that CRPS and the traditionally studied respiratory sinus arrhythmia represent different aspects of the cardiorespiratory interaction, and that key physiologic variables, related to regulatory mechanisms of the cardiac and respiratory systems, which influence respiratory sinus arrhythmia, do not affect CRPS.
Public service interpreting and the politics of entitlement for new entrants to the United Kingdom
Authors: Tipton Rebecca
Published: June 2012

This article examines the function and perception of public service interpreting provision in contemporary Britain against the backdrop of conflict that has emerged in media and political circles as a result of the spiralling cost of such provision. Using an approach based on critical discourse analysis (Fairclough 2000, 2003; Fowler 1991) the article begins by examining a corpus of media reports in which the twin societal aims of community cohesion and integration are often seen as being hindered by translation and interpreting services. The issue of whether interpreting services play or should play a role in integration and cohesion amidst the ongoing processes of welfare reform in Britain is then examined and contrasted with a broader understanding of welfare that foregrounds the role of public service interpreting in the processes of resettlement and socialisation. The discussion also considers the relationship between public service interpreting, welfare reform and status of language services as a welfare entitlement for new entrants.
Conflict recognition, prevention and resolution in mental health interpreting
Authors: Zimányi Krisztina
Published: June 2012

This article investigates the application of Kim’s (2001) theory of communication and cross-cultural adaptation to identifying and resolving areas of conflict in mental health interpreting in Ireland and, by extension, in the wider field of community interpreting. In the context of Kim’s theoretical framework, the interpreter is the ‘stranger,’ a newcomer who undergoes a cross-cultural adaptation process in an unfamiliar environment, i.e. the host community. Potential areas of conflict in community interpreting in general and mental health interpreting in particular are examined in connection with the interrelated factors that underpin Kim’s structure and process models. It is argued that these factors also provide a framework for the mapping of conflict prevention and resolution in community interpreting. Kim’s theory is further extended to examine the complexity of potential conflict between all participants in interpreter-mediated encounters as well as possible prevention and resolution strategies.
Marriage by Correspondence: Politics and Domesticity in the Letters of Isabella d’Este and Francesco Gonzaga, 1490–1519*
Authors: James Carolyn
Published: June 2012

The marriage in 1490 of Francesco Gonzaga, Marquis of Mantua, and Isabella d’Este, daughter of the Duke of Ferrara, cemented an important Italian dynastic alliance and was in no sense a love match. Francesco and Isabella were well aware, however, that they had to establish a harmonious conjugal rapport if the strategic aims of their union were to be realized. This study examines the ways in which the Este-Gonzaga couple built familiarity, affection, and shared interests through frequent letter exchanges that both shaped and facilitated their domestic and political collaboration. The epistolary evidence provides new insights into how an aristocratic Renaissance marriage was experienced by the couple themselves and about the means by which a relationship that was exposed to the full force of contemporary politics, with all its conflicts of dynastic loyalty, was sustained through dialogue and negotiation.
Crystal structure, photoluminescence and electroluminescence of (Ba,Eu)Si2S5
Authors: Nanai Yasushi , Sakamoto Yu , Okuno Tsuyoshi
Published: June 2012

Structural and optical properties of Ba1−x
Eu
x
Si2S5 are investigated for 0 ⩽ x ⩽ 1. A monoclinic structure similar to SrSi2S5 is maintained for the whole range of x. With the increase in x, continuous and isotropic decrease of lattice constants appears because of the replacement of Ba2+ by smaller Eu2+. Raman and infrared absorption spectra show the existence of

anions in BaSi2S5. Green photoluminescence (PL) originating from the 4f65d–4f7 transition of Eu2+ is obtained. The maximum PL efficiency of 52% is found for x = 0.01. Wavelength variation of the PL peak between 500 and 524 nm for 0.01 ⩽ x ⩽ 0.9 can be understood by the presence of two Eu2+ sites having different decay times in Ba
x
Eu1−x
Si2S5. Green PL and electroluminescence are obtained from (Ba,Eu)Si2S5 fabricated on silicon substrate.
Stable isotopes reveal linkages between ocean climate, plankton community dynamics, and survival of two populations of Atlantic salmon (Salmo salar)
Authors: Trueman Clive N. , MacKenzie Kirsteen M. , Palmer Martin R.
Published: June 2012

Trueman, C. N., MacKenzie, K. M., and Palmer, M. R. 2012. Stable isotopes reveal linkages between ocean climate, plankton community dynamics, and survival of two populations of Atlantic salmon (Salmo salar). – ICES Journal of Marine Science, 69: 784–794. An 18-year record of stable isotopes from Atlantic salmon (Salmo salar) migrating to two different regions of the North Atlantic reveals climate-driven subdecadal variations. Time-series of carbon isotopes in one salmon stock, thought to feed in the Faroes/Iceland Basin area, show Subpolar Gyre (SPG) modal variability, which is not seen in fish feeding in the Norwegian Sea. At times of weak SPG circulation, when waters in the Iceland Basin are relatively warm, carbon isotope values are somewhat negative, suggesting possible changes in phytoplankton community structure. The fluctuations in plankton community dynamics suggested by the stable isotope values are coincident with fluctuations in the estimates of marine mortality in one sea-winter fish feeding in the Norwegian Sea, but not in those feeding in the Iceland Basin. Marine mortality in salmon feeding in the Iceland Basin is therefore likely to be more strongly influenced by factors other than bottom–up control. Time-series analysis of stable isotopes in consumer tissues provides information on the interaction between climate and ecosystem dynamics on the scale of individual stocks and cohorts.
Atlantic water temperature and climate in the Barents Sea, 2000–2009
Authors: Boitsov Vladimir D. , Karsakov Alexey L. , Trofimov Alexander G.
Published: June 2012

Boitsov, V. D., Karsakov, A. L., and Trofimov, A. G. 2012. Atlantic water temperature and climate in the Barents Sea, 2000–2009. – ICES Journal of Marine Science, 69: 833–840. Year-to-year variability in the temperature of Atlantic water (AW), which has a strong influence on the marine climate and ecosystem of the Barents Sea, was analysed using data from the Kola Section. With a positive trend in mean annual temperature during the late 20th century, only positive anomalies were registered during the past decade. In nine of those years, the temperature was warmer than the 1951–2000 long-term mean by 0.5–1.2°C, and in 2006, the historical maximum for the 110-year period of observations along the section was recorded. High air and water temperature coincided with reduced sea-ice cover, especially between October and April, when there is seasonal enlargement of the ice-covered area. An integral climate index (CI) of the Barents Sea based on the variability in temperature of AW, air temperature, and ice cover is presented. A prediction of future Barents Sea climate to 2020 is given by extrapolating the sixth degree polynomial approximating the CI.
The development and use of a spatial database for the determination and characterization of the state of the German Baltic small-scale fishery sector
Authors: Papaioannou Eva A. , Vafeidis Athanasios T. , Quaas Martin F. , Schmidt Jörn O.
Published: June 2012

Papaioannou, E. A., Vafeidis, A. T., Quaas, M. F., and Schmidt, J. O. 2012. The development and use of a spatial database for the determination and characterization of the state of the German Baltic small-scale fishery sector. – ICES Journal of Marine Science, 69: . Although substantial progress has been made in the acquisition and analysis of fishery data, the small-scale fishery (SSF) sector is frequently data deficient, with relevant primary data often being fragmented and incomplete. Also, in contrast to the case of the larger scale sector, a coherent methodological framework for the assessment of the SSF has, in most cases, not been formulated. In the present study, the methodology of developing a database for the German Baltic SSF sector is presented. The aim of the database is to combine fishery primary data effectively and enable the sound determination and characterization of the German Baltic SSF sector. Data used include, among others, fleet data derived from the European Community Fleet Register (CFR) database and logbook data from the German Federal Office for Agriculture and Food (BLE). The database includes information on the technical specifications of SSF vessels (length, engine power, etc.); the sector's operational range; main target species; fishing grounds; landing ports; and weight and price of landings. Results of employing the database for profiling the state of the SSF sector (in 2008) are presented. The results demonstrate the benefits of such an approach within the framework of managing coastal fish resources and fishing activities.
Evaluation of Visible-Near Infrared Reflectance Spectra of Avocado Leaves as a Non-destructive Sensing Tool for Detection of Laurel Wilt
Authors: Sankaran Sindhuja , Ehsani Reza , Inch Sharon A. , Ploetz Randy C.
Published: June 2012

Laurel wilt, caused by the fungus Raffaelea lauricola, affects the growth, development, and productivity of avocado, Persea americana. This study evaluated the potential of visible-near infrared spectroscopy for non-destructive sensing of this disease. The symptoms of laurel wilt are visually similar to those caused by freeze damage (leaf necrosis). In this work, we performed classification studies with visible-near infrared spectra of asymptomatic and symptomatic leaves from infected plants, as well as leaves from freeze-damaged and healthy plants, both of which were non-infected. The principal component scores computed from principal component analysis were used as input features in four classifiers: linear discriminant analysis, quadratic discriminant analysis (QDA), Naïve-Bayes classifier, and bagged decision trees (BDT). Among the classifiers, QDA and BDT resulted in classification accuracies of higher than 94% when classifying asymptomatic leaves from infected plants. All of the classifiers were able to discriminate symptomatic-infected leaves from freeze-damaged leaves. However, the false negatives mainly resulted from asymptomatic-infected leaves being classified as healthy. Analyses of average vegetation indices of freeze-damaged, healthy (non-infected), asymptomatic-infected, and symptomatic-infected leaves indicated that the normalized difference vegetation index and the simple ratio index were statistically different.
First Report of the Root-Lesion Nematode, Pratylenchus alleni Associated with Damage on Soybean in Quebec, Canada
Authors: Bélair G. , Mimee B. , Duceppe M. O. , Miller S.
Published: June 2012

In eastern Canada, soybean, Glycine max (L.) Merr., is the most important cultivated legume species. In 2011, the provinces of Ontario and Quebec had 987,400 and 300,000 ha of soybean production, respectively. Root-lesion nematodes, Pratylenchus spp., are the most prevalent plant-parasitic nematodes in Canadian agroecosystems and can affect many crops (3). In 2011, irregular patches of stunted soybean plants were observed for the first time in a 10-ha soybean field grown on a light texture soil in St. Anicet, Quebec (45°4′50.51″N, 74°21′18.56″W). Yield reduction in damaged plots ranged from 38 to 54% when compared with asymptomatic adjacent plots. The field was sown with soybean cv. PRO 2715R (PRO Seeds of Canada, Woodstock, ON), a Roundup Ready cultivar of 2,750 CHU, at 100 kg/ha. Soil analysis revealed a uniform pH of 6.0 ± 0.2 on a gravelly sandy soil (81% sand, 10% loam, 9% clay, and 4% organic matter). On 7 October 2011, root samples were collected from 10 randomly selected damaged patches, washed under running water, and deposited in a mist chamber for a 14-day extraction period. Specimens were stored in tap water at 4°C before identification. Based on morphological characteristics, 26 individual specimens were examined (14 females, 11 males, one juvenile) and were all identified as Pratylenchus alleni Ferris, 1961 (2). Genomic DNA was extracted from individual larvae and the internal transcribed spacers (ITS) region was amplified. RFLP analysis with five restriction enzymes (CfoI, DdeI, HindIII, HpaII, and PstI) showed that the banding pattern for this species was different from those of 18 other major Pratylenchus species (4). Sequence of ITS regions of this population (GenBank Accession No. JX081545) confirmed genus identification but showed only limited homology (<85%) with the 20 Pratylenchus species available in the database at this time. Based on the morphological identification and the ITS sequence divergence with other important species, the sequence was deposited as the first P. alleni accession in GenBank. In the United States, the pathogenicity of P. alleni to soybean is well established (1). To our knowledge, this is the first report of P. alleni occurrence and damage to soybean in Canada. The outbreak of this root-lesion nematode will pose a new challenge for crop management since no registered compounds are currently available against this pest in soybean in Canada.

References: (1) N. Acosta and R. B. Malek. J. Nematol. 13:6, 1981. (2) V. Ferris. Proc. Helminthological Soc. Washington 28:109, 1961. (3) J. W. Potter and A. W. McKeown. Can. J. Soil Sci. 83:289, 2003. (4) L. Waeyenberge et al. Nematol. 2:135, 2000.
Genetic Composition of Phytophthora infestans in Canada Reveals Migration and Increased Diversity
Authors: Kalischuk Melanie L. , Al-Mughrabi Khalil I. , Peters Rick D. , Howard Ron J. , Platt H. W. (Bud) , Kawchuk Lawrence M.
Published: June 2012

A dramatic increase in the incidence of late blight and changes within populations of Phytophthora infestans have been observed in various regions of Canada. In this study, the occurrence of several new genotypes of the pathogen was documented with associated phenotypes that dominated pathogen populations. Genotype US-23, previously detected only among isolates from the United States, dominated in the western Canadian provinces of British Columbia, Alberta (AB), Saskatchewan, and Manitoba (MB). Although isolates of US-23 infect both potato and tomato, these isolates were the only genotype recovered from commercial garden centers in Canada. Isolates of genotype US-8, previously dominant throughout Canada, represented the only genotype detected from the eastern Canadian provinces of New Brunswick and Prince Edward Island. Isolates of other genotypes detected in Canada included US-11 in AB, US-24 in MB, and US-22 in Ontario (ON). An additional genotype was detected in ON which appears to be a derivative of US-22 that may have arisen through sexual reproduction. However, evidence of clonal reproduction dominated among the isolates collected, and opportunities for sexual reproduction were probably limited because of a surprising geographic separation of the A1 and A2 mating types in Canada. Sensitivity of the US-22, US-23, and US-24 isolates to the fungicide metalaxyl, movement of potato seed and transplants, and weather conditions may have contributed to reduced opportunities for contact between the mating types in fields in Canada. All P. infestans isolates were readily distinguished from other related oomycetes with RG57 restriction fragment length polymorphism analysis. Long-distance movement in seed tubers and garden center transplants may have contributed to the rapid spread of the P. infestans genotypes across Canada. Tracking pathogen movement and population composition should improve the ability to predict the genotypes expected each year in different regions of Canada.
Assessment of Infection by Fusarium pseudograminearum in Wheat Seedling Tissues Using Quantitative PCR and a Visual Discoloration Scale
Authors: Knight Noel L. , Sutherland Mark W. , Martin Anke , Herde Damian J.
Published: June 2012

Assessment among cereal genotypes of relative seedling resistance to the crown rot pathogen Fusarium pseudograminearum has been primarily based on visual discoloration of the leaf sheaths. This study is the first to investigate the relationship between the widely used visual rating of seedling leaf sheath discoloration and the degree of colonization of these tissues by the pathogen, based on quantitative polymerase chain reaction (qPCR) of fungal DNA using primers specific for the translation elongation factor α sequence. Fourteen-day-old seedlings of four hard white spring wheat genotypes which differ in their degree of resistance to the pathogen, based on the expression of visible symptoms, were inoculated using a droplet method and assessed weekly from 7 to 35 days after inoculation (dai) for both discoloration and fungal DNA content per unit of tissue weight. Both visual assessment of disease symptoms and qPCR of fungal biomass indicated significant differences between the partially resistant and susceptible wheat genotypes from 14 dai. Visual discoloration of leaf sheath tissues was strongly correlated with fungal biomass estimated by qPCR in all four genotypes; however, this correlation became weaker with increasing time after inoculation. Significant correlations between these parameters were indicated at 14, 21, and 28 dai whereas, by 35 dai, the correlation was not significant. Evaluation of plants at 14 dai provided a rapid test which gave clear discrimination between lines for both parameters and was the time point of closest correlation between fungal colonization and disease symptoms. Symptom expression at all times following inoculation was accompanied by tissue infection, and at no time was symptomless infection observed under this screening environment. These qPCR results confirm that visual assessments of disease symptoms reflect the extent of tissue colonization by the pathogen in recently colonized tissues and confirm the validity of visual assessments for disease rating in high-throughput screening of breeding materials.
Parents lend a helping hand to their offspring in plant defence
Authors: Walters Dale R. , Paterson Linda
Published: June 2012

Plants under attack by pathogens and pests can mount a range of inducible defences, encompassing both chemical and structural changes. Although few reports exist, it appears that plants responding to pathogen or herbivore attack, or chemical defence elicitors, may produce progeny that are better able to defend themselves against attack, compared with progeny from unthreatened or untreated plants. To date, all research on transgenerational effects of biotic stress has been conducted on dicotyledenous plants. We examined the possibility that resistance induced by application of chemical defence elicitors to the monocot plant barley, could be passed on to the progeny. Plants were treated with acibenzolar-S-methyl (ASM) or saccharin, and grain harvested at maturity. Germination was unaffected in seed collected from plants treated with saccharin, while germination was reduced significantly in seed collected from ASM-treated plants. The subsequent growth of the seedlings was not significantly different in any of the treatments. However, plants from parents treated with both ASM or saccharin exhibited significantly enhanced resistance to infection byRhynchosporium commune,despite not being treated with elicitor themselves. These data hint at the possibility of producing disease-resistant plants by exposing parent plants to chemical elicitors.
Table scraps: inter-trophic food provisioning by pumas
Authors: Elbroch L. Mark , Wittmer Heiko U.
Published: June 2012

Large carnivores perform keystone ecological functions through direct predation, or indirectly, through food subsidies to scavengers or trophic cascades driven by their influence on the distributions of their prey. Pumas (
Puma concolor
) are an elusive, cryptic species difficult to study and little is known about their inter-trophic-level interactions in natural communities. Using new GPS technology, we discovered that pumas in Patagonia provided 232 ± 31 kg of edible meat/month/100 km
2
to near-threatened Andean condors (
Vultur gryphus
) and other members of a diverse scavenger community. This is up to 3.1 times the contributions by wolves (
Canis lupus
) to communities in Yellowstone National Park, USA, and highlights the keystone role large, solitary felids play in natural systems. These findings are more pertinent than ever, for managers increasingly advocate controlling pumas and other large felids to bolster prey populations and mitigate concerns over human and livestock safety, without a full understanding of the potential ecological consequences of their actions.
Inferring social network structure in ecological systems from spatio-temporal data streams
Authors: Psorakis Ioannis , Roberts Stephen J. , Rezek Iead , Sheldon Ben C.
Published: June 2012

We propose a methodology for extracting social network structure from spatio-temporal datasets that describe timestamped occurrences of individuals. Our approach identifies temporal regions of dense agent activity and links are drawn between individuals based on their co-occurrences across these ‘gathering events’. The statistical significance of these connections is then tested against an appropriate null model. Such a framework allows us to exploit the wealth of analytical and computational tools of network analysis in settings where the underlying connectivity pattern between interacting agents (commonly termed the
adjacency matrix
) is not given
a priori
. We perform experiments on two large-scale datasets (greater than 10
6
points) of great tit
Parus major
wild bird foraging records and illustrate the use of this approach by examining the temporal dynamics of pairing behaviour, a process that was previously very hard to observe. We show that established pair bonds are maintained continuously, whereas new pair bonds form at variable times before breeding, but are characterized by a rapid development of network proximity. The method proposed here is general, and can be applied to any system with information about the temporal co-occurrence of interacting agents.
Models of collective cell behaviour with crowding effects: comparing lattice-based and lattice-free approaches
Authors: Plank Michael J. , Simpson Matthew J.
Published: June 2012

Individual-based models describing the migration and proliferation of a population of cells frequently restrict the cells to a predefined lattice. An implicit assumption of this type of lattice-based model is that a proliferative population will always eventually fill the lattice. Here, we develop a new lattice-free individual-based model that incorporates cell-to-cell crowding effects. We also derive approximate mean-field descriptions for the lattice-free model in two special cases motivated by commonly used experimental set-ups. Lattice-free simulation results are compared with these mean-field descriptions and with a corresponding lattice-based model. Data from a proliferation experiment are used to estimate the parameters for the new model, including the cell proliferation rate, showing that the model fits the data well. An important aspect of the lattice-free model is that the confluent cell density is not predefined, as with lattice-based models, but an emergent model property. As a consequence of the more realistic, irregular configuration of cells in the lattice-free model, the population growth rate is much slower at high cell densities and the population cannot reach the same confluent density as an equivalent lattice-based model.
Ion-implanted polytetrafluoroethylene enhances
Saccharomyces cerevisiae
biofilm formation for improved immobilization
Authors: Tran Clara T. H. , Kondyurin Alexey , Hirsh Stacey L. , McKenzie David R. , Bilek Marcela M. M.
Published: June 2012

The surface of polytetrafluoroethylene (PTFE) was modified using plasma immersion ion implantation (PIII) with the aim of improving its ability to immobilize yeast. The density of immobilized cells on PIII-treated and -untreated PTFE was compared as a function of incubation time over 24 h. Rehydrated yeast cells attached to the PIII-treated PTFE surface more rapidly, with higher density, and greater attachment strength than on the untreated surface. The immobilized yeast cells were removed mechanically or chemically with sodium hydroxide and the residues left on the surfaces were analysed with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The results revealed that the mechanism of cell attachment on both surfaces differs and a model is presented for each. Rapid attachment on the PIII-treated surface occurs through covalent bonds of cell wall proteins and the radicals on the treated surface. In contrast, on the untreated surface, only physisorbed molecules were found in the residue and lipids were more highly concentrated than proteins. The presence of lipids in the residue was found to be a consequence of damage to the plasma membrane during the rehydration process and the increased cell stress was also apparent by the amount of Hsp12 in the protein residue. The immobilized yeast cells on PIII-treated PTFE were found to be as active as yeast cells in suspension.
Evolution of locomotion in Anthropoidea: the semicircular canal evidence
Authors: Ryan Timothy M. , Silcox Mary T. , Walker Alan , Mao Xianyun , Begun David R. , Benefit Brenda R. , Gingerich Philip D. , Köhler Meike , Kordos László , McCrossin Monte L. , Moyà-Solà Salvador , Sanders William J. , Seiffert Erik R. , Simons Elwyn , Zalmout Iyad S. , Spoor Fred
Published: June 2012

Our understanding of locomotor evolution in anthropoid primates has been limited to those taxa for which good postcranial fossil material and appropriate modern analogues are available. We report the results of an analysis of semicircular canal size variation in 16 fossil anthropoid species dating from the Late Eocene to the Late Miocene, and use these data to reconstruct evolutionary changes in locomotor adaptations in anthropoid primates over the last 35 Ma. Phylogenetically informed regression analyses of semicircular canal size reveal three important aspects of anthropoid locomotor evolution: (i) the earliest anthropoid primates engaged in relatively slow locomotor behaviours, suggesting that this was the basal anthropoid pattern; (ii) platyrrhines from the Miocene of South America were relatively agile compared with earlier anthropoids; and (iii) while the last common ancestor of cercopithecoids and hominoids likely was relatively slow like earlier stem catarrhines, the results suggest that the basal crown catarrhine may have been a relatively agile animal. The latter scenario would indicate that hominoids of the later Miocene secondarily derived their relatively slow locomotor repertoires.