bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymptotic equilibrium between Langmuir turbulence and suprathermal electrons
Authors: Yoon Peter H.
Published: December 2011

In both laboratory and natural environment such as the solar wind, suprathermal, or non-Maxwellian electron distributions are frequently observed. Electron velocity distribution functions containing non-Maxwellian, power-law energetic tail component are often modeled by the so-called kappa distribution, but their physical origin is not clearly understood. In a series of publications, the present author and his colleagues discussed the self-consistent formation of kappa-like distributions as a result of electron-Langmuir turbulence interaction process. However, these discussions were either based upon numerical initial value solution of the weak turbulence equation or by direct particle-in-cell simulation method. It was not evident that the formation of kappa-like state, which was demonstrated during the long-time evolution of the system, did indeed correspond to the genuine asymptotically steady-state solution or not in a mathematical sense. The present paper presents the self-consistent asymptotic solution of the electrons-Langmuir turbulence system and shows that the non-Maxwellian kappa-like state does indeed correspond to a rigorous solution.
Parallel and perpendicular velocity sheared flows driven tripolar vortices in an inhomogeneous electron-ion quantum magnetoplasma
Authors: Mirza Arshad M. , Masood W.
Published: December 2011

Nonlinear equations governing the dynamics of finite amplitude drift-ion acoustic-waves are derived by taking into account sheared ion flows parallel and perpendicular to the ambient magnetic field in a quantum magnetoplasma comprised of electrons and ions. It is shown that stationary solution of the nonlinear equations can be represented in the form of a tripolar vortex for specific profiles of the equilibrium sheared flows. The tripolar vortices are, however, observed to form on very short scales in dense quantum plasmas. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.
Isotope mass and charge effects in tokamak plasmas
Authors: Pusztai I. , Candy J. , Gohil P.
Published: December 2011

The effect of primary ion species of differing charge and mass—specifically, deuterium, hydrogen, and helium—on instabilities and transport is studied in DIII-D plasmas through gyrokinetic simulations with gyro [J. Candy and E. Belli, General Atomics Technical Report No. GA-A26818, 2010]. In linear simulations under imposed similarity of the profiles, there is an isomorphism between the linear growth rates of hydrogen isotopes, but the growth rates are higher for Z > 1 main ions due to the appearance of the charge in the Poisson equation. On ion scales the most significant effect of the different electron-to-ion mass ratio appears through collisions stabilizing trapped electron modes. In nonlinear simulations, significant favorable deviations from pure gyro-Bohm scaling are found due to electron-to-ion mass ratio effects and collisions. The presence of any non-trace impurity species cannot be neglected in a comprehensive simulation of the transport; including carbon impurity in the simulations caused a dramatic reduction of energy fluxes. The transport in the analyzed deuterium and helium discharges could be well reproduced in gyrokinetic and gyrofluid simulations while the significant hydrogen discrepancy is the subject of ongoing investigation.
Energy budgets in collisionless magnetic reconnection: Ion heating and bulk acceleration
Authors: Aunai N. , Belmont G. , Smets R.
Published: December 2011

This paper investigates the energy transfer in the process of collisionless antiparallel magnetic reconnection. Using two-dimensional hybrid simulations, we measure the increase of the bulk and thermal kinetic energies and compare it to the loss of magnetic energy through a contour surrounding the ion decoupling region. It is shown, for both symmetric and asymmetric configurations, that the loss of magnetic energy is not equally partitioned between heating and acceleration. The heating is found to be dominant and the partition ratio depends on the asymptotic parameters, and future investigations will be needed to understand this dependence.
Nuclear quadrupole resonance lineshape analysis for different motional models: Stochastic Liouville approach
Authors: Kruk D. , Earle K. A. , Mielczarek A. , Kubica A. , Milewska A. , Moscicki J.
Published: December 2011

A general theory of lineshapes in nuclear quadrupole resonance (NQR), based on the stochastic Liouville equation, is presented. The description is valid for arbitrary motional conditions (particularly beyond the valid range of perturbation approaches) and interaction strengths. It can be applied to the computation of NQR spectra for any spin quantum number and for any applied magnetic field. The treatment presented here is an adaptation of the “Swedish slow motion theory,” [T. Nilsson and J. Kowalewski, J. Magn. Reson. 146, 345 (2000)10.1006/jmre.2000.2125] originally formulated for paramagnetic systems, to NQR spectral analysis. The description is formulated for simple (Brownian) diffusion, free diffusion, and jump diffusion models. The two latter models account for molecular cooperativity effects in dense systems (such as liquids of high viscosity or molecular glasses). The sensitivity of NQR slow motion spectra to the mechanism of the motional processes modulating the nuclear quadrupole interaction is discussed.
Self-localized domain walls at π-conjugated branching junctions
Authors: Shin Yongwoo , Lin Xi
Published: December 2011

Self-localized domain walls are found trapped at the potential wells created by π-conjugated branching junctions due to the intrinsic electron-phonon couplings. The potential well depths are 0.14 eV for soliton, 0.28 eV for polaron, and 0.32 eV for exciton using the adapted Su-Schrieffer-Heeger model Hamiltonian, as compared to 0.23 eV for soliton, 0.25 eV for positively charged polaron, 0.33 eV for negatively charged polaron, and 0.21 eV for exciton using the ab initio Hartree-Fock method. Once the junction trapping wells are filled, however, branching junctions turn repulsive to additional self-localized domain walls. Torsions around the branching junction center have significant effects on the junction band gap and electron localizations.
Stimuli-response of charged diblock copolymer brushes
Authors: Meng Dong , Wang Qiang
Published: December 2011

Following our previous work on the solvent-response of uncharged diblock copolymer brushes (D. Meng and Q. Wang, J. Chem. Phys. 130, 134904 (2009)), we have performed continuum self-consistent field calculations to study the response (i.e., changes of brush height and surface-layer composition) of diblock brushes with only one block charged to various external stimuli, including solvent selectivity, solution pH, ionic strength, and applied electric field. Our study revealed complex interplay among various stimuli, which needs to be well understood in order to design smart surfaces from charged diblock brushes.
The effective properties of three-dimensional giant magnetostrictive composites
Authors: Gao Yuanwen , Zhang Juanjuan
Published: December 2011

In this work, we have proposed a general 3D analytical model for giant magnetostrictive composites based on the Mori-Tanaka theory. Taking into consideration both the interface effect and thermal residual stress (TRS) in the curing process, we have studied the relationship between the effective magnetostriction of giant magnetostrictive composites and different magnetic fields, and investigated the influence of TRS, inclusion shape, and direction of the magnetic field on the effective magnetostriction. The results show that TRS has significant influence on the effective magnetostrictive normal strains but little effect on the effective magnetostrictive shear strains. Both the magnetic field direction and the inclusion shape significantly affect the effective magnetostriction. Moreover, the Wiedemann effect is expected to occur on the giant magnetostrictive composites according to our theoretical calculations.
Robust thermal performance of Sr2Si5N8:Eu2+: An efficient red emitting phosphor for light emitting diode based white lighting
Authors: Brinkley Stuart E. , Pfaff Nathan , Denault Kristin A. , Zhang Zhijun , (Bert) Hintzen H. T. , Seshadri Ram , Nakamura Shuji , DenBaars Steven P.
Published: December 2011

An important component to the advent of solid state lighting technology is the development of inorganic crystalline phosphors for efficient conversion of photons from blue light emitting diodes (LEDs) to other visible wavelengths for greater color rendering and “warmer” white lighting. We present the results of a recently developed rare earth doped nitride-based red emitting phosphor, Sr2Si5N8:Eu2+, combined with GaN-based blue emitting LEDs and YAG:Ce phosphor for improved white lighting applications. A unique remote phosphor packaging approach was used in all testing to isolate LED performance from phosphor performance. Luminous efficacies were achieved at 94 lm/W with an improved color rendering index (CRI) of 72, mixing red phosphor with YAG:Ce. The Sr2Si5N8:Eu2+ red emitting phosphor was found to have a low temperature sensitivity (only 28% power reduction at 150 °C) and greater luminous performance at low concentrations in the encapsulant by weight relative to other typical red emitting phosphors.
Differences in anti-predator traits of a native bivalve following invasion by a habitat-forming seaweed
Authors: Wright Jeffrey T. , Byers James E. , Koukoumaftsis Loni P. , Gribben Paul E.
Published: December 2011

Invasive habitat-forming species cause large changes to the abiotic environment, which may lead to lethal and sublethal effects on native fauna. In this study, we tested whether morphological anti-predator traits of an infaunal bivalve, Anadara trapezia, differed between areas invaded by the habitat-forming seaweed Caulerpa taxifolia and uninvaded habitats in estuaries in New South Wales, Australia. Caulerpa changes the abiotic environment in ways that may affect traits of native species. In particular, there is lower water flow, lower dissolved oxygen in the water and sediments are more silty and anoxic than in unvegetated habitat. To test our hypotheses, we collected Anadara from Caulerpa and uninvaded habitats and measured shell thickness, shell strength and resistance to opening of valves. We found that all three traits were reduced in Anadara from Caulerpa habitat compared with Anadara from uninvaded habitats. These findings are consistent with the idea that trait modifications in native fauna in response to invasive habitat-forming species can potentially increase susceptibility to predation.
Role of structurally and magnetically modified nanoclusters in colossal magnetoresistance
Authors: Tao Jing , Niebieskikwiat Dario , Jie Qing , Schofield Marvin A. , Wu Lijun , Li Qiang , Zhu Yimei
Published: December 2011

It is generally accepted that electronic and magnetic phase separation is the origin of many of exotic properties of strongly correlated electron materials, such as colossal magnetoresistance (CMR), an unusually large variation in the electrical resistivity under applied magnetic field. In the simplest picture, the two competing phases are those associated with the material state on either side of the phase transition. Those phases would be paramagnetic insulator and ferromagnetic metal for the CMR effect in doped manganites. It has been speculated that a critical component of the CMR phenomenon is nanoclusters with quite different properties than either of the terminal phases during the transition. However, the role of these nanoclusters in the CMR effect remains elusive because the physical properties of the nanoclusters are hard to measure when embedded in bulk materials. Here we show the unexpected behavior of the nanoclusters in the CMR compound La

1-
x

Ca

x

MnO
3
(0.4 ≤ 
x
 < 0.5) by directly correlating transmission electron microscopy observations with bulk measurements. The structurally modified nanoclusters at the CMR temperature were found to be ferromagnetic and exhibit much higher electrical conductivity than previously proposed. Only at temperatures much below the CMR transition, the nanoclusters are antiferromagnetic and insulating. These findings substantially alter the current understanding of these nanoclusters on the material’s functionality and would shed light on the microscopic study on the competing spin-lattice-charge orders in strongly correlated systems.
Retinoblastoma (Rb) regulates laminar dendritic arbor reorganization in retinal horizontal neurons
Authors: Martins Rodrigo A. P. , Davis Denise , Kerekes Ryan , Zhang Jiakun , Bayazitov Ildar T. , Hiler Daniel , Karakaya Mahmut , Frase Sharon , Gleason Shaun , Zakharenko Stanislav S. , Johnson Dianna A. , Dyer Michael A.
Published: December 2011

Neuronal differentiation with respect to the acquisition of synaptic competence needs to be regulated precisely during neurogenesis to ensure proper formation of circuits at the right place and time in development. This regulation is particularly important for synaptic triads among photoreceptors, horizontal cells (HCs), and bipolar cells in the retina, because HCs are among the first cell types produced during development, and bipolar cells are among the last. HCs undergo a dramatic transition from vertically oriented neurites that form columnar arbors to overlapping laminar dendritic arbors with differentiation. However, how this process is regulated and coordinated with differentiation of photoreceptors and bipolar cells remains unknown. Previous studies have suggested that the retinoblastoma (
Rb
) tumor suppressor gene may play a role in horizontal cell differentiation and synaptogenesis. By combining genetic mosaic analysis of individual synaptic triads with neuroanatomic analyses and multiphoton live imaging of developing HCs, we found that Rb plays a cell-autonomous role in the reorganization of horizontal cell neurites as they differentiate. Aberrant vertical processes in
Rb
-deficient HCs form ectopic synapses with rods in the outer nuclear layer but lack bipolar dendrites. Although previous reports indicate that photoreceptor abnormalities can trigger formation of ectopic synapses, our studies now demonstrate that defects in a postsynaptic partner contribute to the formation of ectopic photoreceptor synapses in the mammalian retina.
Rapid experience-dependent plasticity of synapse function and structure in ferret visual cortex in vivo
Authors: Yu Hongbo , Majewska Ania K. , Sur Mriganka
Published: December 2011

The rules by which visual experience influences neuronal responses and structure in the developing brain are not well understood. To elucidate the relationship between rapid functional changes and dendritic spine remodeling in vivo, we carried out chronic imaging experiments that tracked visual responses and dendritic spines in the ferret visual cortex following brief periods of monocular deprivation. Functional changes, which were largely driven by loss of deprived eye responses, were tightly regulated with structural changes at the level of dendritic spines, and occurred very rapidly (on a timescale of hours). The magnitude of functional changes was correlated with the magnitude of structural changes across the cortex, and both these features reversed when the deprived eye was reopened. A global rule governed how the responses to the two eyes or changes in spines were altered by monocular deprivation: the changes occurred irrespective of regional ocular dominance preference and were independently mediated by each eye, and the loss or gain of responses/spines occurred as a constant proportion of predeprivation drive by the deprived or nondeprived eye, respectively.
Structural and energetic evidence for highly peptide-specific tumor antigen targeting via allo-MHC restriction
Authors: Simpson Amy A. , Mohammed Fiyaz , Salim Mahboob , Tranter Amy , Rickinson Alan B. , Stauss Hans J. , Moss Paul A. H. , Steven Neil M. , Willcox Benjamin E.
Published: December 2011

Immunotherapies targeting peptides presented by allogeneic MHC molecules offer the prospect of circumventing tolerance to key tumor-associated self-antigens. However, the degree of antigen specificity mediated by alloreactive T cells, and their ability to discriminate normal tissues from transformed cells presenting elevated antigen levels, is poorly understood. We examined allorecognition of an HLA-A2–restricted Hodgkin's lymphoma-associated antigen and were able to isolate functionally antigen-specific allo-HLA-A2–restricted T cells from multiple donors. Binding and structural studies, focused on a prototypic allo-HLA-A2–restricted T-cell receptor (TCR) termed NB20 derived from an HLA-A3 homozygote, suggested highly peptide-specific allorecognition that was energetically focused on antigen, involving direct recognition of a distinct allopeptide presented within a conserved MHC recognition surface. Although NB20/HLA-A2 affinity was unremarkable, TCR/MHC complexes were very short-lived, consistent with suboptimal TCR triggering and tolerance to low antigen levels. These data provide strong molecular evidence that within the functionally heterogeneous alloreactive repertoire, there is the potential for highly antigen-specific “allo-MHC–restricted” recognition and suggest a kinetic mechanism whereby allo-MHC–restricted T cells may discriminate normal from transformed tissue, thereby outlining a suitable basis for broad-based therapeutic targeting of tolerizing tumor antigens.
microRNA-34a regulates neurite outgrowth, spinal morphology, and function
Authors: Agostini Massimiliano , Tucci Paola , Steinert Joern R. , Shalom-Feuerstein Ruby , Rouleau Matthieu , Aberdam Daniel , Forsythe Ian D. , Young Kenneth W. , Ventura Andrea , Concepcion Carla P. , Han Yoon-Chi , Candi Eleonora , Knight Richard A. , Mak Tak W. , Melino Gerry
Published: December 2011

The p53 family member TAp73 is a transcription factor that plays a key role in many biological processes, including neuronal development. In particular, we have shown that p73 drives the expression of miR-34a, but not miR-34b and c, in mouse cortical neurons. miR-34a in turn modulates the expression of synaptic targets including synaptotagmin-1 and syntaxin-1A. Here we show that this axis is retained in mouse ES cells committed to differentiate toward a neurological phenotype. Moreover, overexpression of miR-34a alters hippocampal spinal morphology, and results in electrophysiological changes consistent with a reduction in spinal function. Therefore, the TAp73/miR-34a axis has functional relevance in primary neurons. These data reinforce a role for miR-34a in neuronal development.
Experimental free energy surfaces reveal the mechanisms of maintenance of protein solubility
Authors: De Simone Alfonso , Dhulesia Anne , Soldi Gemma , Vendruscolo Michele , Hsu Shang-Te Danny , Chiti Fabrizio , Dobson Christopher M.
Published: December 2011

The identification of the factors that enable normally folded proteins to remain in their soluble and functional states is crucial for a comprehensive understanding of any biological system. We have determined a series of energy landscapes of the acylphosphatase from
Drosophila melanogaster
under a variety of conditions by combining NMR measurements with restrained molecular dynamics simulations. We thus analyzed the differences in the structures, dynamics, and energy surfaces of the protein in its soluble state or in situations where it aggregates through conformational states that have native-like structure, folding stability, and enzymatic activity. The study identifies the nature of the energy barriers that under normal physiological conditions prevent the protein ensemble from populating dangerous aggregation-prone states. We found that such states, although similar to the native conformation, have altered surface charge distribution, alternative topologies of the β-sheet region, and modified solvent exposure of hydrophobic surfaces and aggregation-prone regions of the sequence. The identified barriers allow the protein to undergo functional dynamics while remaining soluble and without a significant risk of misfolding and aggregation into nonfunctional and potentially toxic species.
Reverse signaling through the costimulatory ligand CD137L in epithelial cells is essential for natural killer cell-mediated acute tissue inflammation
Authors: Kim Hye J. , Lee Jong S. , Kim Jung D. , Cha Hee J. , Kim Ahra , Lee Sun K. , Lee Sang C. , Kwon Byoung S. , Mittler Robert S. , Cho Hong R. , Kwon Byungsuk
Published: December 2011

Renal ischemia-reperfusion injury (IRI) after kidney transplantation is a major cause of delayed graft function. Even though IRI is recognized as a highly coordinated and specific process, the pathways and mechanisms through which the innate response is activated are poorly understood. In this study, we used a mouse model of acute kidney IRI to examine whether the interactions of costimulatory receptor CD137 and its ligand (CD137L) are involved in the early phase of acute kidney inflammation caused by IRI. We report here that the specific expressions of CD137 on natural killer cells and of CD137L on tubular epithelial cells (TECs) are required for acute kidney IRI. Reverse signaling through CD137L in TECs results in their production of the chemokine (C-X-C motif) receptor 2 ligands CXCL1 and CXCL2 and the subsequent induction of neutrophil recruitment, resulting in a cascade of proinflammatory events during kidney IRI. Our findings identify an innate pathogenic pathway for renal IRI involving the natural killer cell–TEC–neutrophil axis, whereby CD137–CD137L interactions provide the causal contribution of epithelial cell dysregulation to renal IRI. The CD137L reverse signaling pathway in epithelial cells therefore may represent a good target for blocking the initial stage of inflammatory diseases, including renal IRI.
Large-area optoelastic manipulation of colloidal particles in liquid crystals using photoresponsive molecular surface monolayers
Authors: Martinez Angel , Mireles Hector C. , Smalyukh Ivan I.
Published: December 2011

Noncontact optical trapping and manipulation of micrometer- and nanometer-sized particles are typically achieved by use of forces and torques exerted by tightly focused high-intensity laser beams. Although they were instrumental for many scientific breakthroughs, these approaches find few technological applications mainly because of the small-area manipulation capabilities, the need for using high laser powers, limited application to anisotropic fluids and low-refractive-index particles, as well as complexity of implementation. To overcome these limitations, recent research efforts have been directed toward extending the scope of noncontact optical control through the use of optically-guided electrokinetic forces, vortex laser beams, plasmonics, and optofluidics. Here we demonstrate manipulation of colloidal particles and self-assembled structures in nematic liquid crystals by means of single-molecule-thick, light-controlled surface monolayers. Using polarized light of intensity from 1,000 to 100,000 times smaller than that in conventional optical tweezers, we rotate, translate, localize, and assemble spherical and complex-shaped particles of various sizes and compositions. By controlling boundary conditions through the monolayer, we manipulate the liquid crystal director field and the landscape of ensuing elastic forces exerted on colloids by the host medium. This permits the centimeter-scale, massively parallel manipulation of particles and complex colloidal structures that can be dynamically controlled by changing illumination or assembled into stationary stable configurations dictated by the “memorized” optoelastic potential landscape due to the last illumination pattern. We characterize the strength of optically guided elastic forces and discuss the potential uses of this noncontact manipulation in fabrication of novel optically- and electrically-tunable composites from liquid crystals and colloids.
Chemoresponsive alternating supramolecular copolymers created from heterocomplementary calix[4]pyrroles
Authors: Park Jung Su , Yoon Ki Youl , Kim Dong Sub , Lynch Vincent M. , Bielawski Christopher W. , Johnston Keith P. , Sessler Jonathan L.
Published: December 2011

The importance of noncovalent interactions in the realm of biological materials continues to inspire efforts to create artificial supramolecular polymeric architectures. These types of self-assembled materials hold great promise as environmentally stimuli-responsive materials because they are capable of adjusting their various structural parameters, such as chain length, architecture, conformation, and dynamics, to new surrounding environments upon exposure to appropriate external stimuli. Nevertheless, in spite of considerable advances in the area of responsive materials, it has proved challenging to create synthetic self-assembled materials that respond to highly disparate analytes and whose environmentally induced changes in structure can be followed directly through both various spectroscopic and X-ray diffraction analyses. Herein, we report a new set of artificial self-assembled materials obtained by simply mixing two appropriately chosen, heterocomplementary macrocyclic receptors, namely a tetrathiafulvalene-functionalized calix[4]pyrrole and a bis(dinitrophenyl)-meso-substituted calix[4]pyrrole. The resulting polymeric materials, stabilized by combination of donor–acceptor and hydrogen bonding interactions, undergo dynamic, reversible dual guest-dependent structural transformations upon exposure to two very different types of external chemical inputs, namely chloride anion and trinitrobenzene. The structure and dynamics of the copolymers and their analyte-dependent responsive behavior was established via single crystal X-ray crystallography, SEM, heterocomplementary isodesmic analysis, 1- and 2D NMR, and dynamic light scattering spectroscopies. Our results demonstrate the benefit of using designed heterocomplementary interactions of two functional macrocyclic receptors to create synthetic, self-assembled materials for the development of “smart” sensory materials that mimic the key biological attributes of multianalyte recognition and substrate-dependent multisignaling.
Resilience and stability in bird guilds across tropical countryside
Authors: Karp Daniel S. , Ziv Guy , Zook Jim , Ehrlich Paul R. , Daily Gretchen C.
Published: December 2011

The consequences of biodiversity decline in intensified agricultural landscapes hinge on surviving biotic assemblages. Maintaining crucial ecosystem processes and services requires resilience to natural and anthropogenic disturbances. However, the resilience and stability of surviving biological communities remain poorly quantified. From a 10-y dataset comprising 2,880 bird censuses across a land-use gradient, we present three key findings concerning the resilience and stability of Costa Rican bird communities. First, seed dispersing, insect eating, and pollinating guilds were more resilient to low-intensity land use than high-intensity land use. Compared with forest assemblages, bird abundance, species richness, and diversity were all ∼15% lower in low-intensity land use and ∼50% lower in high-intensity land use. Second, patterns in species richness generally correlated with patterns in stability: guilds exhibited less variation in abundance in low-intensity land use than in high-intensity land use. Finally, interspecific differences in reaction to environmental change (response diversity) and possibly the portfolio effect, but not negative covariance of species abundances, conferred resilience and stability. These findings point to the changes needed in agricultural production practices in the tropics to better sustain bird communities and, possibly, the functional and service roles that they play.
Structural basis for gating charge movement in the voltage sensor of a sodium channel
Authors: Yarov-Yarovoy Vladimir , DeCaen Paul G. , Westenbroek Ruth E. , Pan Chien-Yuan , Scheuer Todd , Baker David , Catterall William A.
Published: December 2011

Voltage-dependent gating of ion channels is essential for electrical signaling in excitable cells, but the structural basis for voltage sensor function is unknown. We constructed high-resolution structural models of resting, intermediate, and activated states of the voltage-sensing domain of the bacterial sodium channel NaChBac using the Rosetta modeling method, crystal structures of related channels, and experimental data showing state-dependent interactions between the gating charge-carrying arginines in the S4 segment and negatively charged residues in neighboring transmembrane segments. The resulting structural models illustrate a network of ionic and hydrogen-bonding interactions that are made sequentially by the gating charges as they move out under the influence of the electric field. The S4 segment slides 6–8 Å outward through a narrow groove formed by the S1, S2, and S3 segments, rotates ∼30°, and tilts sideways at a pivot point formed by a highly conserved hydrophobic region near the middle of the voltage sensor. The S4 segment has a 3
10
-helical conformation in the narrow inner gating pore, which allows linear movement of the gating charges across the inner one-half of the membrane. Conformational changes of the intracellular one-half of S4 during activation are rigidly coupled to lateral movement of the S4–S5 linker, which could induce movement of the S5 and S6 segments and open the intracellular gate of the pore. We confirmed the validity of these structural models by comparing with a high-resolution structure of a NaChBac homolog and showing predicted molecular interactions of hydrophobic residues in the S4 segment in disulfide-locking studies.
Structural basis for basal activity and autoactivation of abscisic acid (ABA) signaling SnRK2 kinases
Authors: Ng Ley-Moy , Soon Fen-Fen , Zhou X. Edward , West Graham M. , Kovach Amanda , Suino-Powell Kelly M. , Chalmers Michael J. , Li Jun , Yong Eu-Leong , Zhu Jian-Kang , Griffin Patrick R. , Melcher Karsten , Xu H. Eric
Published: December 2011

Abscisic acid (ABA) is an essential hormone that controls plant growth, development, and responses to abiotic stresses. Central for ABA signaling is the ABA-mediated autoactivation of three monomeric Snf1-related kinases (SnRK2.2, -2.3, and -2.6). In the absence of ABA, SnRK2s are kept in an inactive state by forming physical complexes with type 2C protein phosphatases (PP2Cs). Upon relief of this inhibition, SnRK2 kinases can autoactivate through unknown mechanisms. Here, we report the crystal structures of full-length
Arabidopsis thaliana
SnRK2.3 and SnRK2.6 at 1.9- and 2.3-Å resolution, respectively. The structures, in combination with biochemical studies, reveal a two-step mechanism of intramolecular kinase activation that resembles the intermolecular activation of cyclin-dependent kinases. First, release of inhibition by PP2C allows the SnRK2s to become partially active because of an intramolecular stabilization of the catalytic domain by a conserved helix in the kinase regulatory domain. This stabilization enables SnRK2s to gain full activity by activation loop autophosphorylation. Autophosphorylation is more efficient in SnRK2.6, which has higher stability than SnRK2.3 and has well-structured activation loop phosphate acceptor sites that are positioned next to the catalytic site. Together, these data provide a structural framework that links ABA-mediated release of PP2C inhibition to activation of SnRK2 kinases.
The future of research universities
Authors: Rip Arie
Published: December 2011

The paper considers the future of the research university and finds that it is unlikely to continue adherence to a business model in which strategy is determined and directed from the top. A Mode 2 perspective suggests that the sector will contain a variety of forms, the characteristics of each shaped by the performance of centres of excellence and relevance.
Paradox and potential: trends in science policy and practice in Canada and New Zealand
Authors: Halliwell Janet , Smith Willie
Published: December 2011

Over the last 30 years, Canada and New Zealand have redirected their science and research systems to meet changing national priorities, and in response to global trends and needs. They have shared a common effort to transform their traditionally resource-based economies. Both are committed to the creation of knowledge-based economies that can compete internationally in the face of massive globalization and the rise of the BRIC nations (Brazil, Russia, India and China). Research, and science and technology, are seen as the primary drivers towards this goal.

Canada and New Zealand developed science systems shaped by their common British heritage. In recent years, their science systems have undergone fundamental changes, yet they continue to share many evolving trends, highlighted in the ideas, methods, values and norms identified as Mode 2, in The New Production of Knowledge. These trends, however, have been shaped by different policies and different institutional arrangements, different theoretical perspectives and different political ideologies.
What can bibliometrics tell us about changes in the mode of knowledge production?
Authors: Martin Ben
                      R.
Published: December 2011

One of the most influential contributions to the fields of science policy research and science and technology studies during the last 20 years was The New Production of Knowledge by Gibbons et al. (Gibbons, M., Limoges, C., Nowotny, H., Schwartzman, S., Scott, P. and Trow, M. (1994) The New Production of Knowledge: The Dynamics of Science and Research in Contemporary Societies, Sage, London). The authors argued that over recent decades a different form of knowledge production has emerged, one which they termed ‘Mode 2’. In this, knowledge is produced in the context of application, generally on the basis of transdisciplinary research efforts, by a heterogeneous range of institutional actors, who are subject to wider social accountability and more diverse forms of quality control than in the traditional ‘Mode 1’ knowledge production. Although there have been a number of attempts to examine the claims of The New Production of Knowledge empirically, the evidence is, at best, rather ambiguous. The study reported here analyses highly cited publications in the field of bibliometric research to establish whether the themes of those publications and, more specifically, the changes in these themes over the last 20 years, provide any evidence of a growing incidence of Mode 2 knowledge production. The paper concludes that there is some evidence that bibliometrics, as a field of research, has exhibited a shift towards Mode 2 knowledge production over the last two decades. In addition, it would seem to have played a part in a similar shift across science more generally, offering policy-relevant tools and analyses, helping scientific research to respond to increased demands for accountability, and contributing to changes in the approach to the quality assessment of research. At the same time, and perhaps inadvertently, it may have contributed to bringing about changes in publication and citation practices as more and more authors seek to maximise their ‘score’ on one or more bibliometric indicators.
Guanylate binding protein 1 is a novel effector of EGFR-driven invasion in glioblastoma
Authors: Li Ming , Mukasa Akitake , del-Mar Inda Maria , Zhang Jianhua , Chin Lynda , Cavenee Webster , Furnari Frank
Published: December 2011

Although GBP1 (guanylate binding protein 1) was among the first interferon-inducible proteins identified, its function is still largely unknown. Epidermal growth factor receptor (EGFR) activation by amplification or mutation is one of the most frequent genetic lesions in a variety of human tumors. These include glioblastoma multiforme (GBM), which is characterized by independent but interrelated features of extensive invasion into normal brain parenchyma, rapid growth, necrosis, and angiogenesis. In this study, we show that EGFR activation promoted GBP1 expression in GBM cell lines through a signaling pathway involving Src and p38 mitogen-activated protein kinase. Moreover, we identified YY1 (Yin Yang 1) as the downstream transcriptional regulator regulating EGFR-driven GBP1 expression. GBP1 was required for EGFR-mediated MMP1 (matrix metalloproteinase 1) expression and glioma cell invasion in vitro. Although deregulation of GBP1 expression did not affect glioma cell proliferation, overexpression of GBP1 enhanced glioma cell invasion through MMP1 induction, which required its C-terminal helical domain and was independent of its GTPase activity. Reducing GBP1 levels by RNA interference in invasive GBM cells also markedly inhibited their ability to infiltrate the brain parenchyma of mice. GBP1 expression was high and positively correlated with EGFR expression in human GBM tumors and cell lines, particularly those of the neural subtype. Together, these findings establish GBP1 as a previously unknown link between EGFR activity and MMP1 expression and nominate it as a novel potential therapeutic target for inhibiting GBM invasion.
Reversing the Tapestry:Prison of Lovein Text, Image, and Textile*
Authors: Francomano Emily C.
Published: December 2011

In the 1520s the internationally popular romancePrison of Lovewas adapted as a series of tapestries known asL'Histoire de Lérian et Lauréolle. This article explores the translation of the romance to a larger-than-life, three-dimensional narrative object created from sumptuous materials that literally enveloped courtly life. Unlike previous studies ofPrison of Love's international reach, this article reads the tapestry chamber as an integral part of the romance's complex history of transmission among the princely courts of Europe in the early sixteenth century. Further, study of the textiles’ production, use, and reception will show that the tapestry chamber, though incomplete, is material evidence of a particular sixteenth-century reading of the romance.
Hymnic Epic andThe Faerie Queene’s Original Printed Format: Canto-Canticles and Psalmic Arguments*
Authors: Borris Kenneth , Donaldson Clark Meredith
Published: December 2011

When Edmund Spenser (1552?–99) published hisFaerie Queenein 1590 and 1596, two pervasive structural features would have seemed surprising: the abbreviationCant.in sectional and running titles, used instead ofCanto;and a four-line stanza of common meter for each section's argument, instead of a more expansive and prestigious stanza. Study of the relevant early modern Italian and English norms of publication indicates that these were complementary and innovative means of merging heroic form with divine poetry and hymnic discourse, and recognized as such.Cant.readily suggestedcanticleand the Solomonic Canticles, and the poet himself calls one of his so-called cantos a “canticle” (4.5.46). In style and prosodic form, his arguments would have particularly evoked the nationally distinctive Elizabethan Protestant psalmody and hymnody, as well as popular ballads. By incorporating these two metamorphic devices intoThe Faerie Queene's framework, Spenser reconfigured the heroic poem to serve his different, English vision.
Children's Behavior in the Postanesthesia Care Unit: The Development of the Child Behavior Coding System-PACU (CBCS-P)
Authors: Chorney Jill MacLaren , Tan Edwin T. , Martin Sarah R. , Fortier Michelle A. , Kain Zeev N.
Published: December 2011

Objective To develop and validate a behavioral coding measure, the Children's Behavior Coding System-PACU (CBCS-P), for children's distress and nondistress behaviors while in the postanesthesia recovery unit. Methods A multidisciplinary team examined videotapes of children in the PACU and developed a coding scheme that subsequently underwent a refinement process (CBCS-P). To examine the reliability and validity of the coding system, 121 children and their parents were videotaped during their stay in the PACU. Participants were healthy children undergoing elective, outpatient surgery and general anesthesia. The CBCS-P was utilized and objective data from medical charts (analgesic consumption and pain scores) were extracted to establish validity. Results Kappa values indicated good-to-excellent (κ's > .65) interrater reliability of the individual codes. The CBCS-P had good criterion validity when compared to children's analgesic consumption and pain scores. Conclusions The CBCS-P is a reliable, observational coding method that captures children's distress and nondistress postoperative behaviors. These findings highlight the importance of considering context in both the development and application of observational coding schemes.
First Report of Bacterial Leaf Spot of Basil Caused by Pseudomonas viridiflava in Hungary
Authors: Végh A. , Hevesi M. , Némethy Zs. , Palkovics L.
Published: December 2011

In April 2011, typical bacterial spot symptoms were observed on sweet basil plantlets (Ocimum basilicum L.) in a supermarket in Budapest, Hungary. Affected plants had dark brown-to-black lesions on the cotyledons. Spots on the leaves were first water soaked and then became necrotic and progressed inward from the margins. Symptoms were similar to those reported by Little et al. (3) on basil affected by Pseudomonas viridiflava. Bacteria consistently isolated from leaf lesions formed mucoid colonies with a green fluorescent pigment on King's B medium. Strains were gram negative. In LOPAT (levan-oxidase-potato rot-arginine dihydrolase-tobacco hypersensitivity) tests (2), all induced a hypersensitive reaction (HR) in tobacco (Nicotiana tabacum L. cv. White Burley) leaves (1), caused soft rot of potato tuber slices, and were negative for levan, oxidase, and arginine dihydrolase. Biochemical tests, API 20NE and API 50 CH (Biomérieux, Marcy l'Etoile, France), were also used for identification. The pathogenicity of three isolates was tested twice by injecting 20-day-old healthy basil plants with a bacterial suspension (107 CFU/ml). Controls were injected with sterile distilled water. Plants were kept at 25 to 28°C and 80 to 100% relative humidity. Forty-eight hours after inoculation, dark brown-to-black lesions were observed only on inoculated plants. The bacterium was reisolated from lesions of all plants tested, fulfilling Koch's postulates. No lesions were observed on controls. To identify the pathogen, a PCR technique was used. The 16SrDNA region was amplified with general bacterial primer pair (63f forward and 1389r reverse) (4) then the PCR products were cloned into Escherichia coli DH5α cells and a recombinant plasmid was sequenced by M13 forward and reverse primers. The sequence was deposited in GenBank (Accession No. HE585219). On the basis of the symptoms, biochemical tests, and 16SrDNA sequence homology (99% sequence similarity with a number of P. viridiflava isolates), the pathogen was identified as P. viridiflava. To our knowledge, this is the first report of bacterial leaf spot of basil in Hungary, which can seriously affect the basil production.

References: (1) Z. Klement. Nature 199:299, 1963. (2) R. A. Lelliot et al. Appl. Bacteriol. 29:470, 1966. (3) E. L. Little et al. Plant Dis. 78:831, 1994. (4) A. M. Osborn et al. Environ. Microbiol. 2:39, 2000.
Identification of Race-Specific Resistance in North American Vitis spp. Limiting Erysiphe necator Hyphal Growth
Authors: Ramming David W. , Gabler Franka , Smilanick Joseph L. , Margosan Dennis A. , Cadle-Davidson Molly , Barba Paola , Mahanil Siraprapa , Frenkel Omer , Milgroom Michael G. , Cadle-Davidson Lance
Published: December 2011

Race-specific resistance against powdery mildews is well documented in small grains but, in other crops such as grapevine, controlled analysis of host–pathogen interactions on resistant plants is uncommon. In the current study, we attempted to confirm powdery mildew resistance phenotypes through vineyard, greenhouse, and in vitro inoculations for test cross-mapping populations for two resistance sources: (i) a complex hybrid breeding line, ‘Bloodworth 81-107-11', of at least Vitis rotundifolia, V. vinifera, V. berlandieri, V. rupestris, V. labrusca, and V. aestivalis background; and (ii) Vitis hybrid ‘Tamiami’ of V. aestivalis and V. vinifera origin. Statistical analysis of vineyard resistance data suggested the segregation of two and three race-specific resistance genes from the two sources, respectively. However, in each population, some resistant progeny were susceptible in greenhouse or in vitro screens, which suggested the presence of Erysiphe necator isolates virulent on progeny segregating for one or more resistance genes. Controlled inoculation of resistant and susceptible progeny with a diverse set of E. necator isolates clearly demonstrated the presence of fungal races differentially interacting with race-specific resistance genes, providing proof of race specificity in the grape powdery mildew pathosystem. Consistent with known race-specific resistance mechanisms, both resistance sources were characterized by programmed cell death of host epidermal cells under appressoria, which arrested or slowed hyphal growth; this response was also accompanied by collapse of conidia, germ tubes, appressoria, and secondary hyphae. The observation of prevalent isolates virulent on progeny with multiple race-specific resistance genes before resistance gene deployment has implications for grape breeding strategies. We suggest that grape breeders should characterize the mechanisms of resistance and pyramid multiple resistance genes with different mechanisms for improved durability.
A Deletion in NRT2.1 Attenuates Pseudomonas syringae-Induced Hormonal Perturbation, Resulting in Primed Plant Defenses
Authors: Camañes Gemma , Pastor Victoria , Cerezo Miguel , García-Andrade Javier , Vicedo Begonya , García-Agustín Pilar , Flors Victor
Published: December 2011

For an efficient defense response against pathogens, plants must coordinate rapid genetic reprogramming to produce an incompatible interaction. Nitrate Trasnporter2 (NRT2) gene family members are sentinels of nitrate availability. In this study, we present an additional role for NRT2.1 linked to plant resistance against pathogens. This gene antagonizes the priming of plant defenses against the bacterial pathogen Pseudomonas syringae pv tomato DC3000 (Pst). The nrt2 mutant (which is deficient in two genes, NRT2.1 and NRT2.2) displays reduced susceptibility to this bacterium. We demonstrate that modifying environmental conditions that stimulate the derepression of the NRT2.1 gene influences resistance to Pst independently of the total level of endogenous nitrogen. Additionally, hormonal homeostasis seemed to be affected in nrt2, which displays priming of salicylic acid signaling and concomitant irregular functioning of the jasmonic acid and abscisic acid pathways upon infection. Effector-triggered susceptibility and hormonal perturbation by the bacterium seem to be altered in nrt2, probably due to reduced sensitivity to the bacterial phytotoxin coronatine. The main genetic and metabolic targets of coronatine in Arabidopsis (Arabidopsis thaliana) remain largely unstimulated in nrt2 mutants. In addition, a P. syringae strain defective in coronatine synthesis showed the same virulence toward nrt2 as the coronatine-producing strain. Taken together, the reduced susceptibility of nrt2 mutants seems to be a combination of priming of salicylic acid-dependent defenses and reduced sensitivity to the bacterial effector coronatine. These results suggest additional functions for NRT2.1 that may influence plant disease resistance by down-regulating biotic stress defense mechanisms and favoring abiotic stress responses.