bluuebunny/crossref_metadata_2025 huggingface dataset:
Mediators of mineralocorticoid receptor-induced profibrotic inflammatory responses in the heart
Authors: Wilson Peter , Morgan James , Funder John W. , Fuller Peter J. , Young Morag J.
Published: November 2008

Coronary, vascular and perivascular inflammation in rats following MR (mineralocorticoid receptor) activation plus salt are well-characterized precursors for the appearance of cardiac fibrosis. Endogenous corticosterone, in the presence of the 11βHSD2 (11β hydroxysteroid dehydrogenase type 2) inhibitor CBX (carbenoxolone) plus salt, produces similar inflammatory responses and tissue remodelling via activation of MR. MR-mediated oxidative stress has previously been suggested to account for these responses. In the present study we thus postulated that when 11βHSD2 is inhibited, endogenous corticosterone bound to unprotected MR in the vessel wall may similarly increase early biomarkers of oxidative stress. Uninephrectomized rats received either DOC (deoxycorticosterone), CBX or CBX plus the MR antagonist EPL (eplerenone) together with 0.9% saline to drink for 4, 8 or 16 days. Uninephrectomized rats maintained on 0.9% saline for 8 days served as controls. After 4 days, both DOC and CBX increased both macrophage infiltration and mRNA expression of the p22phox subunit of NADPH oxidase, whereas CBX, but not DOC, increased expression of the NOX2 (gp91phox) subunit. eNOS [endothelial NOS (NO synthase)] mRNA expression significantly decreased from 4 days for both treatments, and iNOS (inducible NOS) mRNA levels increased after 16 days of DOC or CBX; co-administration of EPL inhibited all responses to CBX. The responses characterized over this time course occurred before measurable increases in cardiac hypertrophy or fibrosis. The findings of the present study support the hypothesis that endogenous corticosterone in the presence of CBX can activate vascular MR to produce both inflammatory and oxidative tissue responses well before the onset of fibrosis, that the two MR ligands induce differential but overlapping patterns of gene expression, and that elevation of NOX2 subunit levels does not appear necessary for full expression of MR-mediated inflammatory and fibrogenic responses.
Sonographic Measurement of the Fetal Iliac Bone: Growth and Relation to Femur Length in Assessment of Gestational Age
Authors: Jaffe Richard , Santolaya Joaquim , Warsof Steven L.
Published: November 2008

Diagnostic ultrasonography has given us the opportunity to diagnose several congenital malformations in utero. Skeletal dysplasias is a heterogeneous group of disorders of the skeleton. Although disorders of bone growth are often diagnosed in utero, it is usually a general diagnosis because the exact syndrome cannot be specified. This is due to the fact that many anomal ies of the skeleton have similar features. The wing of the iliac bone can be either affected or normal in skeletal dysplasias and its appearance may help in the differential diagnosis. This study was undertaken to establish values for the width of the iliac bone wing during normal gestations and thus enable us to use it in the evaluation of fetal growth and the recognition of specific congenital anomalies.
Use of Magnetic Resonance Imaging in the Diagnosis of Takayasu's Arteritis During Pregnancy: A Case Report
Authors: Coel Marc , Saito Robert , Endo Patti Murakami
Published: November 2008

We report a case of Takayasu's arteritis in a 29-year-old primigravid woman. The diagnosis of Takayasu's arteritis is usually made on the basis of clinical findings, with definitive diagnosis being made by angiography. To avoid the large amount of radiation needed for angiography, we used magnetic resonance imaging to establish a presumptive diagnosis. The diagnosis was confirmed two weeks postpartum by angiography.
Fetal Periventricular Hemorrhage in von Willebrand's Disease: Short Review and First Case Presentation
Authors: Mullaart Reinier A. , Van Dongen Pieter , Gabreëls Fons J.M. , van Oostrom Cor
Published: November 2008

We present the first case of fetal periventricular hemorrhage due to type lla Von Willebrand's disease. Discussed are the causal relationships between fetal hemostatic disorders and periventricular hemorrhage, the risks of labor and delivery, and the management with respect to antenatal diagnosis, fetal therapy, and delivery.
Sonographic Findings in Septo-Optic Dysplasia in the Fetus and Newborn Infant
Authors: Pilu Gianluigi , Sandri Fabrizio , Cerisoli Marziano , Alvisi Carlo , Salvioli Gian Paolo , Bovicelli Luciano
Published: November 2008

A 28-year-old primigravida woman was referred for ultrasound studies at 27 weeks' gestation. Sonographic examination found enlarged cerebral ventricles, communicating lateral ventricles, bilateral cleft lip and palate. A 2500 gm male infant was delivered at 36 weeks' gestation, after which the diagnosis of septo-optic dysplasia was made.
Sonographic Findings in a Case of Cloverleaf Skull Deformity and Prune Belly
Authors: Bracero Luis A. , Clark David , Pieffer Marianne , Fakhry Joseph
Published: November 2008

A rare case of cloverleaf skull is reported that was not diagnosed in utero. The case is more unusual because it was not associated with hydrocephalus and was associated with prune belly.
Growth dynamics of nanodiamonds synthesized by pulsed-laser ablation
Authors: Tian F. , Sun J. , Hu S. L. , Du X. W.
Published: November 2008

We performed theoretical analysis on nanodiamonds (NDs) generated by pulsed-laser ablation to investigate its growth dynamics. The final size of NDs was calculated by combining the growth velocity with growth time. The result shows that the radius and density of plasma plume determine the cooling velocity, and the growth time correlates with the cooling velocity. Theoretical calculations are in good agreement with experimental results and give reasonable explanation on the formation of ultrafine NDs.
Edge states in quantum Hall effect in graphene (Review Article)
Authors: Gusynin V. P. , Miransky V. A. , Sharapov S. G. , Shovkovy I. A.
Published: November 2008

We review recent results concerning the spectrum of edge states in the quantum Hall effect in graphene. In particular, special attention is paid to the derivation of the conditions under which gapless edge states exist in the spectrum of graphene with “zigzag” and “armchair” edges. It is found that in the case of a half-plane or a ribbon with zigzag edges, there are gapless edge states only when a spin gap dominates over a Dirac mass gap. In the case of a half-plane with an armchair edge, the existence of the gapless edge states depends on the specific type of Dirac mass gaps. The implications of these results for the dynamics in the quantum Hall effect in graphene are discussed.
The Berry phase in graphene and graphite multilayers
Authors: Mikitik G. P. , Sharlai Yu. V.
Published: November 2008

We discuss the electron energy spectra and the Berry phases for graphene, a graphite bilayer, and bulk graphite, allowing for a small spin-orbit interaction. If an electron orbit in the Brillouin zone surrounds several Dirac points (band-contact lines in graphite), one can find the relative signs of the Berry phases generated by these points (lines) by taking this interaction into account.
Spectral function of graphene with short-range impurity centers
Authors: Skrypnyk Yu. V. , Loktev V. M.
Published: November 2008

The spectral function of graphene with point substitutional defects is calculated for different impurity concentrations. It is demonstrated that features in the spectral function of graphene observed in ARPES experiments can be caused by the presence of a well-defined resonance state and are clearly pronounced at the impurity concentrations, which are of the order of the critical concentration for the impurity-induced spectrum rearrangement.
Vacuum polarization in graphene with a topological defect
Authors: Sitenko Yu. A. , Vlasii N. D.
Published: November 2008

The influence of a topological defect in graphene on the ground state of electronic quasiparticle excitations is studied in the framework of the long-wavelength continuum model originating in the tight-binding approximation for the nearest-neighbor interaction in the graphitic lattice. A topological defect that rolls up a graphitic sheet into a nanocone is represented by a pointlike pseudomagnetic vortex with a flux which is related to the deficit angle of the cone. The method of self-adjoint extensions is employed to define the set of physically acceptable boundary conditions at the apex of the nanocone. The electronic system on a graphitic nanocone is found to acquire a ground-state condensate and current of special type, and we determine the dependence of these quantities on the deficit angle of the nanocone, the continuous parameter of the boundary condition at the apex, and the distance from the apex.
On the dynamics of piezoactuated positioning systems
Authors: Chen X. B. , Zhang Q. S. , Kang D. , Zhang W. J.
Published: November 2008

Piezoelectric actuators (PEAs) are commercially available for producing extremely small displacements. If a PEA is used to drive a positioning mechanism, the combined dynamics is approximated empirically by that of a second-order system. However, the rationale for such an approximation is lacking in the literature, thus leaving some issues unaddressed, such as the scope of and the error associated with the approximation. This paper presents such a rationale for the second-order approximation and a method to quantify the error associated with the approximation, by employing the assumed mode method to solve the governing equation. For the experimental verification, step voltages of 48.2, 64.2, and 75.4 V were used to excite a prototype of the positioning system with a mass ratio of 24.7, 47.7, 87.5, 115.8, and 138.8, respectively; and the measured system step responses were compared to the ones simulated by using the second-order approximation. Also, it is illustrated that the error associated with the approximation can be well characterized and quantified by using the developed method.
Analysis of the optical properties of Cu(In1−xGax)3Se5 crystals
Authors: León M. , Serna R. , Levcenko S. , Gurieva G. , Merino J. M. , Friedrich E. J. , Arushanov E.
Published: November 2008

Analysis of the optical properties of bulk Cu(In1−xGax)3Se5 mixed crystals synthesized from the elements as a function of the Ga content is presented. Measurements of the complex dielectric function ε(ω)=ε1(ω)+iε2(ω) were performed at room temperature in the photon energy range of 0.8–4.7 eV using a variable angle of incidence ellipsometer. The spectral dependence of the complex refractive index, the absorption coefficient, and the normal-incidence reflectivity were also derived. The structure observed in the dielectric functions attributed to the interband transitions E0, E1A, and E1B has been modeled using a modification of the Adachi’s model. The results are in excellent agreement with the experimental data over the entire range of photon energies. The model parameters, including the energies corresponding to the lowest direct gap and higher critical points, have been determined using the simulated annealing algorithm. The values of E0 and E1A are found to increase linearly with the increasing Ga content.
Implementation on a desktop computer of the real time feedback control loop of a scanning probe microscope
Authors: Aloisi G. , Bacci F. , Carlà M. , Dolci D. , Lanzi L.
Published: November 2008

A software package has been developed to implement the real time feedback control loop needed in scanning probe microscopy on a general purpose desktop computer of the current high-speed/multicore generation. The main features of the implementation of both the feedback loop and the control of the experiment on the same computer are discussed. The package can work with several general purpose data acquisition boards and can be extended in a modular way to further board models; timing performance has been tested with several hardware configurations and some applications common in scanning probe microscopy. The package is available under an Open Source license.
On the assumptions underlying milestoning
Authors: Vanden-Eijnden Eric , Venturoli Maddalena , Ciccotti Giovanni , Elber Ron
Published: November 2008

Milestoning is a procedure to compute the time evolution of complicated processes such as barrier crossing events or long diffusive transitions between predefined states. Milestoning reduces the dynamics to transition events between intermediates (the milestones) and computes the local kinetic information to describe these transitions via short molecular dynamics (MD) runs between the milestones. The procedure relies on the ability to reinitialize MD trajectories on the milestones to get the right kinetic information about the transitions. It also rests on the assumptions that the transition events between successive milestones and the time lags between these transitions are statistically independent. In this paper, we analyze the validity of these assumptions. We show that sets of optimal milestones exist, i.e., sets such that successive transitions are indeed statistically independent. The proof of this claim relies on the results of transition path theory and uses the isocommittor surfaces of the reaction as milestones. For systems in the overdamped limit, we also obtain the probability distribution to reinitialize the MD trajectories on the milestones, and we discuss why this distribution is not available in closed form for systems with inertia. We explain why the time lags between transitions are not statistically independent even for optimal milestones, but we show that working with such milestones allows one to compute mean first passage times between milestones exactly. Finally, we discuss some practical implications of our results and we compare milestoning with Markov state models in view of our findings.
An appraisal of Poincaré–Hopf relation and application to topography of molecular electrostatic potentials
Authors: Roy D. , Balanarayan P. , Gadre Shridhar R.
Published: November 2008

The Poincaré–Hopf relation is studied for molecular electrostatic potentials (MESPs) of a few test systems such as cyclopropane, cyclobutane, pyridine, and benzene. Appropriate spheres centered at various points, including the center of mass of the system under study, are constructed and the MESP gradient is evaluated on the corresponding spherical grid. The change in directional nature of MESP gradient on the surface of these spheres gives indication of the critical points of the function. This is used for developing a method for locating the critical points of MESP. The strategy also enables a general definition of the Euler characteristic (EC) of the molecule, independent of any region or space. Further, the effect of basis set and level of theory on the EC is discussed.
First-principles study of the H2 interaction with transition metal (Ti, V, Ni) doped Mg(0001) surface: Implications for H-storage materials
Authors: Banerjee S. , Pillai C. G. S. , Majumder C.
Published: November 2008

Using first-principles calculations we have investigated the interaction of hydrogen molecules with clean and M (Ti, V, and Ni) doped Mg(0001) surfaces. The calculations have been carried out using plane-wave-based pseudopotential method under the formalism of density functional theory. First we have calculated the stability of the M atoms on the Mg surface. On the basis of the energetic criteria, we found that all these M atoms prefer to substitute one of the Mg atoms from the second layer than the top surface atom. In the second step we have studied the interaction of a hydrogen molecule with the clean and doped Mg surface. The results show that for M atoms at the surface, the hydrogen molecule undergoes spontaneous dissociative chemisorptions. However, for M atoms in the second layer, it requires to cross an activation barrier to undergo molecular dissociation. Furthermore, to understand the mobility of hydrogen atoms on the surface we have calculated the diffusion energy barriers for the M doped surface. Contrary to the molecular dissociation behavior, it is found that the mobility of hydrogen atoms on the surface is easier if the M atoms are placed in the second layer in comparison to that in the top surface layer. It is believed that the results of the present study provide useful information based on the first-principles calculations for synthesizing Mg based materials for hydrogen storage with optimal performance.
The electronic structure of the two lowest states of CuC
Authors: Kalemos Apostolos , Dunning Thom H. , Mavridis Aristides
Published: November 2008

State-of-the-art ab initio quantum mechanical methods and large basis sets are employed for the study of the electronic structure of the first two states of CuC, Σ4− and Π2. A one-electron sigma bond state (Σ4−) competes with a two-electron σ-bond state (Π2) for the ground state of the CuC system. The combined effects of core-valence correlation and relativity point to an X-state of Π2 symmetry with De=51.9 kcal/mol and re=1.772 Å. The Σ4− state is predicted to lie 2.1 kcal/mol higher at re=1.787 Å.
Efficient Cherenkov emission of broadband terahertz radiation from an ultrashort laser pulse in a sandwich structure with nonlinear core
Authors: Bodrov S. B. , Bakunov M. I. , Hangyo M.
Published: November 2008

A scheme for efficient generation of broadband terahertz radiation by a femtosecond laser pulse propagating in a planar sandwichlike structure is proposed. The structure consists of a thin nonlinear core cladded with prisms made of a material with low terahertz absorption. The focused into a line laser pulse propagates in the core as a leaky or waveguide mode and emits Cherenkov wedge of terahertz waves in the cladding. We developed a theory that describes terahertz generation in such a structure and calculated spatial distribution of the generated terahertz field, its energy spectrum and optical-to-terahertz conversion efficiency. The developed theory predicts the conversion efficiency of up to several percent in a 1 cm long and 1 cm wide Si–LiNbO3–Si sandwich structure with a 20 μm thick nonlinear layer pumped by 8.5 μJ Ti:sapphire laser with pulse duration of 100 fs.
Poole–Frenkel conduction in single wall carbon nanotube composite films built up by electrostatic layer-by-layer deposition
Authors: Jombert A. S. , Coleman K. S. , Wood D. , Petty M. C. , Zeze D. A.
Published: November 2008

The fabrication of large area thin films of single wall carbon nanotubes (SWCNTs) using electrostatic layer-by-layer deposition is reported. The in-plane current versus voltage (I-V) characteristics were dependent on the concentration of SWCNTs transferred from the solvents onto the substrates. Solutions with a low SWCNT concentration produced films that exhibited a nonlinear I-V regime. The experimental data fitted with various conduction models indicated that Poole–Frenkel conduction was the dominant mechanism. The temperature dependence of the conductivity also supported this model. Two activation energies were identified—approximately 10 and 20 meV. These were thought to be associated with the surfactant coatings of the nanotubes. Increasing the SWCNT loading in the thin films led to an Ohmic conduction process by virtue of a denser network of conductive paths in the film and conduction via tube to tube contacts.
Influence of the substrate misorientation on the properties of N-polar InGaN/GaN and AlGaN/GaN heterostructures
Authors: Keller S. , Suh C. S. , Fichtenbaum N. A. , Furukawa M. , Chu R. , Chen Z. , Vijayraghavan K. , Rajan S. , DenBaars S. P. , Speck J. S. , Mishra U. K.
Published: November 2008

Smooth N-polar InGaN/GaN and AlGaN/GaN multiquantum wells (MQWs) and heterostructures were grown by metal organic chemical vapor deposition on (0001) sapphire substrates with misorientation angles of 2°–5° toward the a-sapphire plane. For all investigated structures the tendency toward formation of multiatomic steps at the film surface and at interfaces increased with increasing misorientation angle. Thereby the crystal misorientation led to a stronger degradation of the interface quality and periodicity of InGaN/GaN in comparison to the AlGaN/GaN MQWs. While the alloy composition of AlGaN films was unaffected by the misorientation, the indium mole fraction in the InGaN layers and the wavelength of the MQW related luminescence decreased with increasing misorientation angle. The properties of the two dimensional electron gas (2DEG), which formed at the upper interface of semi-insulating GaN/AlGaN/GaN heterostructures, were strongly anisotropic. Whereas the resistivity of the 2DEG measured perpendicular to the surface steps/undulations decreased with increasing misorientation angle, the resistivity measured in the parallel direction was significantly lower and unaffected by the crystal misorientation. Electron mobility values as high as 1800 cm2/V s were determined for conduction parallel to the surface steps/undulations.
Microwave-induced forward scattering and Luttinger liquid interferences in magnetically confined quantum wires
Authors: Nogaret A. , Portal J.-C. , Beere H. E. , Ritchie D. A. , Phillips C.
Published: November 2008

We report on the photoresistance of a magnetic quantum wire obtained by applying a gradient of magnetic field to a two-dimensional electron gas. Electron transmission through the magnetic wire increases by an order of magnitude under microwave irradiation and exhibits frequency-dependent magneto-oscillations as a function of the in-plane magnetic field. Both results are fully consistent with microwave-coupled Luttinger liquid edge channels which interfere at two pinning sites in the fashion of a Mach-Zehnder interferometer.
Electrostatic screening and Friedel oscillations in semiconducting nanotubes
Authors: Chaplik A. V. , Magarill L. I. , Vitlina R. Z.
Published: November 2008

In 3D and 2D electronic systems the singular contribution to the static permittivity ε (Kohn singularity) is a small correction to the regular part of ε but it results in the leading term in asymptotic behavior of the screened potential (Friedel oscillations). In the present letter we show that for nanotubes quite different results are valid: ε becomes infinitely large at the singular point and the Friedel oscillations do not play the dominant role in the screening at the large distances. Moreover, the zero and highest cylindrical harmonics of the effective potential are screened by quite different mechanisms.
Giant magnetization of a superconductor-two-dimensional electron gas-superconductor structure
Authors: Romanovsky I. A. , Bogachek E. N. , Landman Uzi , Krive I. V.
Published: November 2008

Superconductivity-induced phase-controlled mesoscopic magnetic effects in a two-dimensional electron gas that bridges two superconducting reservoirs are investigated. Giant paramagnetic response of the junction, occurring at certain values of the phase difference of the order parameter, is predicted. A geometrically similar system, consisting of a graphene ribbon stretched between two superconducting leads, is also considered. The magnetic effects in this system are found to be small, and the difference between the magnetic properties of the two systems is discussed.
Atomic layer structure of manganese atoms on wurtzite gallium nitride (0001¯)
Authors: Chinchore Abhijit , Wang Kangkang , Lin Wenzhi , Pak Jeongihm , Smith Arthur R.
Published: November 2008

Submonolayer quantities of Mn are deposited on wurtzite GaN (0001¯). The surface is monitored using reflection high energy electron diffraction, which shows a pattern consisting of 3× reconstruction along [101¯0], but only 1× along [112¯0]. Diffraction analysis shows that the 3× streak intensity is maximized at ≈0.86 monolayer of Mn deposition. The results indicate that Mn forms linear chains along the [101¯0] direction with a spacing of 3a/2 along chains and 3a/2 between chains. Correcting the peak coverage for sticking coefficient and accounting for the observed periodicities, a 3×3-R30° model, consisting of 2/3 monolayer of Mn atoms, is proposed.
Assessment of surface damage and sidewall implantation in AlGaN-based high electron mobility transistor devices caused during focused-ion-beam milling
Authors: Cullen David A. , Smith David J.
Published: November 2008

The surface amorphization and ion implantation in AlGaN-based high electron mobility transistor (HEMT) model structures caused by ionized gallium during focused-ion-beam milling have been investigated. The extent of Ga+ surface implantation likely to occur during deposition of the surface Pt protective layer was simulated for 30, 5, and 2 keV ion beams. Electron-transparent cross sections of AlGaN/GaN and AlGaN/AlN/GaN HEMT structures were then prepared for electron microscope observation using a dual-beam focused-ion-beam instrument operated at different beam energies. Experimental studies revealed that the upper 9 nm of the AlGaN layer had been amorphized during Pt deposition. Nanoprobe x-ray microanalysis confirmed intermixing with Pt as well as implantation of Ga ions into the upper regions of the foil. Deposition of the first few hundred nanometers of Pt using an electron beam, rather than the usual Ga+ beam, enabled surface damage and ion implantation to be completely avoided. Sidewall damage for specially prepared cross sections was assessed from bright-field and high-angle annular-dark-field images. For final membrane thinning at 30, 5, and 2 keV, the thicknesses of visibly damaged layers were approximately 20, 8, and 4 nm, respectively, roughly twice as large as predicted by simulations.
Experimental observation of narrow surface plasmon resonances in gold nanoparticle arrays
Authors: Chu Yizhuo , Schonbrun Ethan , Yang Tian , Crozier Kenneth B.
Published: November 2008

We demonstrate that coupling between grating diffraction and localized surface plasmons in two-dimensional gold nanoparticle arrays in water leads to narrow near-infrared resonance peaks in measured far field extinction spectra. Good agreement is obtained between finite difference time domain (FDTD) calculations and experimental extinction spectra. The FDTD calculations predict that the gold nanoparticle arrays exhibit near-field electric field intensity (E2) enhancements approximately one order of magnitude greater than those of single isolated gold nanoparticles.
Flexible optical waveguides based on the omnidirectional reflection of one-dimensional photonic crystals
Authors: Chen Bing , Tang Tiantong , Wang Zhaohong , Chen Hao , Liu Zichen
Published: November 2008

An optical wave guiding structure based on the omnidirectional reflection of one-dimensional photonic crystals is presented. The dispersion and transmission characteristics of flexible waveguides using this structure are investigated by numerical simulations using plane wave expansion method and finite-difference time-domain method, respectively. Calculated results indicate that for waveguide bends of arbitrary angles with a curved radius less than several wavelengths, a very high transmission (>97%) over wide frequency range is observed. Owing to this unique advantage of flexibility, it is expected to be applied to highly dense photonic integrated circuits after further research.
Selective growth of carbon nanotube for via interconnects by oxidation and selective reduction of catalyst
Authors: Lee Sunwoo , Moon Seongho , Yoon Hong Sik , Wang Xiaofeng , Kim Dong Woo , Yeo In-Seok , Chung U-In , Moon Joo-Tae , Chung Jaegwan
Published: November 2008

We propose a selective growth approach of carbon nanotubes (CNTs) to prevent interface rupture in CNT via interconnects. Oxidation of the Ni catalyst layer is carried out before via hole patterning and the open hole area of the Ni layer is reduced by annealing in H2 ambient after via hole patterning. It is found that the present scheme provides robust selective growth of CNTs in the via hole and effectively prohibits the interface rupture due to the diffusion of carbon source into the Ni catalyst layer buried under the insulator.
Insecticide resistance and implications for future aphid management in Australian grains and pastures: a review
Authors: Edwards Owain R. , Franzmann Bernie , Thackray Deborah , Micic Svetlana
Published: November 2008

Aphids can cause substantial damage to cereals, oilseeds and legumes through direct feeding and through the transmission of plant pathogenic viruses. Aphid-resistant varieties are only available for a limited number of crops. In Australia, growers often use prophylactic sprays to control aphids, but this strategy can lead to non-target effects and the development of insecticide resistance. Insecticide resistance is a problem in one aphid pest of Australian grains in Australia, the green peach aphid (Myzus persicae). Molecular analyses of field-collected samples demonstrate that amplified E4 esterase resistance to organophosphate insecticides is widespread in Australian grains across Australia. Knockdown resistance to pyrethroids is less abundant, but has an increased frequency in areas with known frequent use of these insecticides. Modified acetylcholinesterase resistance to dimethyl carbamates, such as pirimicarb, has not been found in Australia, nor has resistance to imidacloprid. Australian grain growers should consider control options that are less likely to promote insecticide resistance, and have reduced impacts on natural enemies. Research is ongoing in Australia and overseas to provide new strategies for aphid management in the future.
Host plant resistance in grain crops and prospects for invertebrate pest management in Australia: an overview
Authors: Gu H. , Edwards O. R. , Hardy A. T. , Fitt G. P.
Published: November 2008

An integrated pest management (IPM) approach that relies on an array of tactics is adopted commonly in response to problems with pesticide-based production in many agricultural systems. Host plant resistance is often used as a fundamental component of an IPM system because of the generally compatible, complementary role that pest-resistant crops play with other tactics. Recent research and development in the resistance of legumes and cereals to aphids, sorghum midge resistance, and the resistance of canola varieties to mite and insect pests have shown the prospects of host plant resistance for developing IPM strategies against invertebrate pests in Australian grain crops. Furthermore, continuing advances in biotechnology provide the opportunity of using transgenic plants to enhance host plant resistance in grains.
Host-plant resistance and biopesticides: ingredients for successful integrated pest management (IPM) in Australian sorghum production
Authors: Franzmann B. A. , Hardy A. T. , Murray D. A. H. , Henzell R. G.
Published: November 2008

There are two major pests of sorghum in Australia, the sorghum midge, Stenodiplosis sorghicola (Coquillett), and the corn earworm, Helicoverpa armigera (Hübner). During the past 10 years the management of these pests has undergone a revolution, due principally to the development of sorghum hybrids with resistance to sorghum midge. Also contributing has been the adoption of a nucleopolyhedrovirus for the management of corn earworm. The practical application of these developments has led to a massive reduction in the use of synthetic insecticides for the management of major pests of sorghum in Australia. These changes have produced immediate economic, environmental and social benefits. Other flow-on benefits include providing flexibility in planting times, the maintenance of beneficial arthropods and utilisation of sorghum as a beneficial arthropod nursery, a reduction in midge populations and a reduction in insecticide resistance development in corn earworm. Future developments in sorghum pest management are discussed.
Pests of germinating grain crops in southern Australia: an overview of their biology and management options
Authors: Micic S. , Hoffmann A. A. , Strickland G. , Weeks A. R. , Bellati J. , Henry K. , Nash M. A. , Umina P. A.
Published: November 2008

Grain crops in southern Australia are subject to attack by countless pests, with greater than 40 invertebrate species threatening seedling establishment. Control tactics for crop establishment pests rely heavily on the application of pesticides, especially in canola, which is the most susceptible crop to invertebrate damage. There is genuine interest in integrated pest management (IPM) among growers, but relatively little adoption of classical IPM in broadacre farming in southern Australia. The driving forces behind the lack of adoption are unknown, although over-reliance on broad-spectrum pesticides – which are inexpensive and often applied prophylactically as a means of negating the need to monitor crops – is undoubtedly a key factor. Recent control failures against important pests due to pesticide resistance, increased restrictions on pesticide applications, environmental concerns about pesticide applications and strong support for grain quality assurance programs by exporters, highlight the need to consider IPM principles as a means of reducing chemical inputs. IPM guidelines for broadacre farming systems are limited in scope and there is a need to develop practical management tools that encompass a whole system approach. This paper provides an overview of the main invertebrate pests affecting crop establishment and identifies gaps hindering the wide-scale adoption of IPM.
Metagenome analysis of an extreme microbial symbiosis reveals eurythermal adaptation and metabolic flexibility
Authors: Grzymski Joseph J. , Murray Alison E. , Campbell Barbara J. , Kaplarevic Mihailo , Gao Guang R. , Lee Charles , Daniel Roy , Ghadiri Amir , Feldman Robert A. , Cary Stephen C.
Published: November 2008

Hydrothermal vent ecosystems support diverse life forms, many of which rely on symbiotic associations to perform functions integral to survival in these extreme physicochemical environments.
Epsilonproteobacteria
, found free-living and in intimate associations with vent invertebrates, are the predominant vent-associated microorganisms. The vent-associated polychaete worm,
Alvinella pompejana
, is host to a visibly dense fleece of episymbionts on its dorsal surface. The episymbionts are a multispecies consortium of
Epsilonproteobacteria
present as a biofilm. We unraveled details of these enigmatic, uncultivated episymbionts using environmental genome sequencing. They harbor wide-ranging adaptive traits that include high levels of strain variability analogous to
Epsilonproteobacteria
pathogens such as
Helicobacter pylori
, metabolic diversity of free-living bacteria, and numerous orthologs of proteins that we hypothesize are each optimally adapted to specific temperature ranges within the 10–65 °C fluctuations characteristic of the
A. pompejana
habitat. This strategic combination enables the consortium to thrive under diverse thermal and chemical regimes. The episymbionts are metabolically tuned for growth in hydrothermal vent ecosystems with genes encoding the complete rTCA cycle, sulfur oxidation, and denitrification; in addition, the episymbiont metagenome also encodes capacity for heterotrophic and aerobic metabolisms. Analysis of the environmental genome suggests that
A. pompejana
may benefit from the episymbionts serving as a stable source of food and vitamins. The success of
Epsilonproteobacteria
as episymbionts in hydrothermal vent ecosystems is a product of adaptive capabilities, broad metabolic capacity, strain variance, and virulent traits in common with pathogens.
Selection of a trioxaquine as an antimalarial drug candidate
Authors: Coslédan Frédéric , Fraisse Laurent , Pellet Alain , Guillou François , Mordmüller Benjamin , Kremsner Peter G. , Moreno Alicia , Mazier Dominique , Maffrand Jean-Pierre , Meunier Bernard
Published: November 2008

Trioxaquines are antimalarial agents based on hybrid structures with a dual mode of action. One of these molecules, PA1103/SAR116242, is highly active in vitro on several sensitive and resistant strains of
Plasmodium falciparum
at nanomolar concentrations (e.g., IC
50
value = 10 nM with FcM29, a chloroquine-resistant strain) and also on multidrug-resistant strains obtained from fresh patient isolates in Gabon. This molecule is very efficient by oral route with a complete cure of mice infected with chloroquine-sensitive or chloroquine-resistant strains of
Plasmodia
at 26–32 mg/kg. This compound is also highly effective in humanized mice infected with
P. falciparum
. Combined with a good drug profile (preliminary absorption, metabolism, and safety parameters), these data were favorable for the selection of this particular trioxaquine for development as drug candidate among 120 other active hybrid molecules.
High stimulus unmasks positive feedback in an autoregulated bacterial signaling circuit
Authors: Miyashiro Tim , Goulian Mark
Published: November 2008

We examined the effect of positive autoregulation on the steady-state behavior of the PhoQ/PhoP two-component signaling system in
Escherichia coli
. We found that autoregulation has no effect on the steady-state output for a large range of input stimulus, which was modulated by varying the concentration of magnesium in the growth medium. We provide an explanation for this finding with a simple model of the PhoQ/PhoP circuit. The model predicts that even when autoregulation is manifest across a range of stimulus levels, the effects of positive feedback on the steady-state output emerge only in the limit that the system is strongly stimulated. Consistent with this prediction, amplification associated with autoregulation was observed in growth-limiting levels of magnesium, a condition that strongly activates PhoQ/PhoP. In a further test of the model, we found that strains harboring a phosphatase-defective PhoQ showed strong positive feedback and considerable cell-to-cell variability under growth conditions where the wild-type circuit did not show this behavior. Our results demonstrate a simple and general mechanism for regulating the positive feedback associated with autoregulation within a bacterial signaling circuit to boost response range and maintain a relatively uniform and graded output.
Structure of transmembrane pore induced by Bax-derived peptide: Evidence for lipidic pores
Authors: Qian Shuo , Wang Wangchen , Yang Lin , Huang Huey W.
Published: November 2008

The structures of transmembrane pores formed by a large family of pore-forming proteins and peptides are unknown. These proteins, whose secondary structures are predominantly α-helical segments, and many peptides form pores in membranes without a crystallizable protein assembly, contrary to the family of β-pore-forming proteins, which form crystallizable β-barrel pores. Nevertheless, a protein-induced pore in membranes is commonly assumed to be a protein channel. Here, we show a type of peptide-induced pore that is not framed by a peptide structure. Peptide-induced pores in multiple bilayers were long-range correlated into a periodically ordered lattice and analyzed by X-ray diffraction. We found the pores induced by Bax-derived helical peptides were at least partially framed by a lipid monolayer. Evidence suggests that the formation of such lipidic pores is a major mechanism for α-pore-forming proteins, including apoptosis-regulator Bax.
Regulation of postsynaptic AMPA responses by synaptojanin 1
Authors: Gong Liang-Wei , De Camilli Pietro
Published: November 2008

Endocytosis of postsynaptic AMPA receptors is a mechanism through which efficiency of neurotransmission is regulated. We have genetically tested the hypothesis that synaptojanin 1, a phosphoinositide phosphatase implicated in the endocytosis of synaptic vesicles presynaptically, may also function in the endocytosis of AMPA receptors postsynaptically. Electrophysiological recordings of cultured hippocampal neurons showed that miniature excitatory postsynaptic current amplitudes were larger in synaptojanin 1 knockout (KO) neurons because of an increase of surface-exposed AMPA receptors. This change did not represent an adaptive response to decreased presynaptic release in KO cultures and was rescued by the expression of wild type, but not catalytically inactive synaptojanin 1, in the postsynaptic neuron. NMDA-induced internalization of pHluorin-tagged AMPA receptors (GluR2) was impaired in KO neurons. These results reveal a function of synaptojanin 1 in constitutive and triggered internalization of AMPA receptors and thus indicate a role for phosphatidylinositol(4,5)-bisphosphate metabolism in the regulation of postsynaptic AMPA responses.
Direct demonstration of the cross-bridge recovery stroke in muscle thick filaments in aqueous solution by using the hydration chamber
Authors: Sugi Haruo , Minoda Hiroki , Inayoshi Yuhri , Yumoto Fumiaki , Miyakawa Takuya , Miyauchi Yumiko , Tanokura Masaru , Akimoto Tsuyoshi , Kobayashi Takakazu , Chaen Shigeru , Sugiura Seiryo
Published: November 2008

Despite >50 years of research work since the discovery of sliding filament mechanism in muscle contraction, structural details of the coupling of cyclic cross-bridge movement to ATP hydrolysis are not yet fully understood. An example would be whether lever arm tilting on the myosin filament backbone will occur in the absence of actin. The most direct way to elucidate such movement is to record ATP-induced cross-bridge movement in hydrated thick filaments. Using the hydration chamber, with which biological specimens can be kept in an aqueous environment in an electron microscope, we have succeeded in recording ATP-induced cross-bridge movement in hydrated thick filaments consisting of rabbit skeletal muscle myosin, with gold position markers attached to the cross-bridges. The position of individual cross-bridges did not change appreciably with time in the absence of ATP, indicating stability of time-averaged cross-bridge mean position. On application of ATP, individual cross-bridges moved nearly parallel to the filament long axis. The amplitude of the ATP-induced cross-bridge movement showed a peak at 5–7.5 nm. At both sides of the filament bare region, across which the cross-bridge polarity was reversed, the cross-bridges were found to move away from, but not toward, the bare region. Application of ADP produced no appreciable cross-bridge movement. Because ATP reacts rapidly with the cross-bridges (M) to form complex (M·ADP·Pi) with an average lifetime >10 s, the observed cross-bridge movement is associated with reaction, M + ATP → M·ADP·Pi. The cross-bridges were observed to return to their initial position after exhaustion of ATP. These results constitute direct demonstration of the cross-bridge recovery stroke.
Chaperonin chamber accelerates protein folding through passive action of preventing aggregation
Authors: Apetri Adrian C. , Horwich Arthur L.
Published: November 2008

The original experiments reconstituting GroEL–GroES-mediated protein folding were carried out under “nonpermissive” conditions, where the chaperonin system was absolutely required and substrate proteins could not achieve the native state if diluted directly from denaturant into solution. Under “permissive” conditions, however, employing lower substrate concentration and lower temperature, some substrate proteins can be refolded both by the chaperonin system and while free in solution. For several of these, the protein refolds more rapidly inside the GroEL–GroES
cis
chamber than free in solution, suggesting that the chamber may have an active role in assisting protein folding. Here, we observe that the difference is caused by reversible multimolecular association while folding in solution, an avenue of kinetic partitioning that slows the overall rate of renaturation relative to the chaperonin chamber, where such associations cannot occur. For Rubisco, reversible aggregation during folding in solution was observed by gel filtration. For a mutant of maltose-binding protein (DM-MBP), the rate of folding in solution declined with increasing concentration, and the folding reaction produced light scattering. Under solution conditions where chloride was absent, however, light scattering no longer occurred, and DM-MBP folded at the same rate as in the
cis
cavity. In a further test, dihydrofolate reductase, thermally inactivated in the
cis
cavity or in solution, was substantially reactivated upon temperature downshift in the
cis
cavity but not in solution, where aggregation occurred. We conclude that the GroEL–GroES chamber behaves as a passive “Anfinsen cage” whose primary role is to prevent multimolecular association during folding.
The BH3-only protein Bik/Blk/Nbk inhibits nuclear translocation of activated ERK1/2 to mediate IFNγ-induced cell death
Authors: Mebratu Yohannes A. , Dickey Burton F. , Evans Chris , Tesfaigzi Yohannes
Published: November 2008

IFNγ induces cell death in epithelial cells, but the mediator for this death pathway has not been identified. In this study, we find that expression of Bik/Blk/Nbk is increased in human airway epithelial cells (AECs [HAECs]) in response to IFNγ. Expression of Bik but not mutant BikL61G induces and loss of Bik suppresses IFNγ-induced cell death in HAECs. IFNγ treatment and Bik expression increase cathepsin B and D messenger RNA levels and reduce levels of phospho–extracellular regulated kinase 1/2 (ERK1/2) in the nuclei of bik+/+ compared with bik−/− murine AECs. Bik but not BikL61G interacts with and suppresses nuclear translocation of phospho-ERK1/2, and suppression of ERK1/2 activation inhibits IFNγ- and Bik-induced cell death. Furthermore, after prolonged exposure to allergen, hyperplastic epithelial cells persist longer, and nuclear phospho-ERK is more prevalent in airways of IFNγ−/− or bik−/− compared with wild-type mice. These results demonstrate that IFNγ requires Bik to suppress nuclear localization of phospho-ERK1/2 to channel cell death in AECs.
Dances with leukocytes: how tetraspanin-enriched microdomains assemble to form endothelial adhesive platforms
Authors: Ley Klaus , Zhang Hong
Published: November 2008

Rather than just providing an unstructured adhesive surface for leukocytes, cytokine-activated endothelial cells assemble preexisting tetraspanin-enriched microdomains to form endothelial adhesive platforms (EAPs) and endothelial docking structures. In this issue of the Journal of Cell Biology, Barreiro et al. (Barreiro, O., M. Zamai, M. Yáñez-Mó, E. Tejera, P. López-Romero, P.N. Monk, E. Gratton, V.R. Caiolfa, and F. Sánchez-Madrid. 2008. J. Cell Biol. 183:527–542) show how the immunoglobulin superfamily adhesion molecules intercellular adhesion molecule (ICAM)–1 and vascular cell adhesion molecule (VCAM)–1 form nanoclusters with the tetraspanins CD9 and CD151 in a physiologically relevant system. Furthermore, convincing biochemical data suggest that these structures are distinct from lipid rafts.
Molecular Clustering of STIM1 with Orai1/CRACM1 at the Plasma Membrane Depends Dynamically on Depletion of Ca2+ Stores and on Electrostatic Interactions
Authors: Calloway Nathaniel , Vig Monika , Kinet Jean-Pierre , Holowka David , Baird Barbara
Published: November 2008

Activation of store operated Ca2+ entry involves stromal interaction molecule 1 (STIM1), localized to the endoplasmic reticulum (ER), and calcium channel subunit (Orai1/CRACM1), localized to the plasma membrane. Confocal microscopy shows that thapsigargin-mediated depletion of ER Ca2+ stores in RBL mast cells causes a redistribution of STIM1, labeled with monomeric red fluorescent protein (mRFP), to micrometer-scale ER-plasma membrane junctions that contain Orai1/CRACM1, labeled with monomeric Aequorea coerulescens green fluorescent protein (AcGFP). Using fluorescence resonance energy transfer (FRET), we determine that this visualized coredistribution is accompanied by nanoscale interaction of STIM1-mRFP and AcGFP-Orai1/CRACM1. We find that antigen stimulation of immunoglobulin E receptors causes much less Orai1/CRACM1 and STIM1 association, but strong interaction is observed under conditions that prevent refilling of ER stores. Stimulated association monitored by FRET is inhibited by sphingosine derivatives in parallel with inhibition of Ca2+ influx. Similar structural and functional effects are caused by mutation of acidic residues in the cytoplasmic segment of Orai1/CRACM1, suggesting a role for electrostatic interactions via these residues in the coupling of Orai1/CRACM1 to STIM1. Our results reveal dynamic molecular interactions between STIM1 and Orai1/CRACM1 that depend quantitatively on electrostatic interactions and on the extent of store depletion.