bluuebunny/crossref_metadata_2025 huggingface dataset:
Feeding volcanoes of the Kluchevskoy group from the results of local earthquake tomography
Authors: Koulakov Ivan , Gordeev Evgeniy I. , Dobretsov Nikolay L. , Vernikovsky Valery A. , Senyukov Sergey , Jakovlev Andrey
Published: May 2011

We present a seismic model of the area beneath the Kluchevskoy volcano group (Kamchatka, Russia) based on the tomographic inversion of more than 66000 P and S arrival times from more than 5000 local earthquakes that occurred in 2004 and that were recorded by 17 permanent stations. Below a depth of 25 km beneath the Kluchevskoy volcano, we observed a very strong anomaly in the Vp/Vs ratio that reached as high as 2.2. This is a probable indicator of the presence of partially molten material with a composition corresponding to deeper mantle layers. The upper part of this anomaly at a depth of 25–30 km coincides with a cluster of strong seismicity that can be explained by strong mechanical stresses in the lowermost crust due to magma ascension, water release and/or phase transitions. In the crust, we observed regular seismicity clusters that link the mantle anomaly with the Kluchevskoy volcano and most likely indicate the paths of magma migration. Between depths of 8 and 13 km, we see several patterns of high Vp/Vs ratios, interpreted as intermediate‐depth magma storages. Directly below the Kluchevskoy volcano, we observed a shallow body of high Vp/Vs, which probably represents the activated magma chamber just beneath the volcano cone, which erupted in the beginning of 2005. The existence of three levels of magma storage, based on results of local earthquake tomography, may explain the variety of the lava composition and eruption regimes in different volcanoes of the Kluchevskoy group.
Evolution of the equatorial oscillation in Saturn's stratosphere between 2005 and 2010 from Cassini/CIRS limb data analysis
Authors: Guerlet S. , Fouchet T. , Bézard B. , Flasar F. M. , Simon‐Miller A. A.
Published: May 2011

We present an analysis of thermal infrared spectra acquired in limb viewing geometry by Cassini/CIRS in February 2010. We retrieve vertical profiles of Saturn's stratospheric temperature from 20 hPa to 10−2 hPa, at 9 latitudes between 20°N and 20°S. Using the gradient thermal wind equation, we derive a map of the zonal wind field. Both the temperature and the zonal wind vertical profiles exhibit an oscillation in the equatorial region. These results are compared to the temperature and zonal wind maps obtained from 2005–2006 CIRS limb data, when this oscillation was first reported. In both epochs, strong temperature anomalies at the equator (up to 20K) are consistent with adiabatic heating (cooling) due to a sinking (rising) motion at a speed of 0.1–0.2 mm/s. Finally, we show that the altitude of the maximum eastward wind has moved downwards by 1.3 scale heights in 4.2 years, hence with a ‘phase’ speed of ∼0.5 mm/s. This rate is consistent with the estimated period of 14.7 years for the equatorial oscillation, and requires a local zonal acceleration of 1.1 × 10−6 m.s−2 at the 2.5 hPa pressure level. This downward propagation of the oscillation is consistent with it being driven by absorption of upwardly propagating waves.
BioSharing Overview
Authors: Harland Lee , Communities The BioSharing , Sansone Susanna-Assunta , Field Dawn , Santarsiero Annapaola , Maguire Eamonn , Rocca-Serra Philippe , Taylor Chris
Published: May 2011

Download this poster providing an overview of the BioSharing effort.
Alternative affinity tools: more attractive than antibodies?
Authors: Ruigrok Vincent J. B. , Levisson Mark , Eppink Michel H. M. , Smidt Hauke , van der Oost John
Published: May 2011

Antibodies are the most successful affinity tools used today, in both fundamental and applied research (diagnostics, purification and therapeutics). Nonetheless, antibodies do have their limitations, including high production costs and low stability. Alternative affinity tools based on nucleic acids (aptamers), polypeptides (engineered binding proteins) and inorganic matrices (molecular imprinted polymers) have received considerable attention. A major advantage of these alternatives concerns the efficient (microbial) production and in vitro selection procedures. The latter approach allows for the high-throughput optimization of aptamers and engineered binding proteins, e.g. aiming at enhanced chemical and physical stability. This has resulted in a rapid development of the fields of nucleic acid- and protein-based affinity tools and, although they are certainly not as widely used as antibodies, the number of their applications has steadily increased in recent years. In the present review, we compare the properties of the more conventional antibodies with these innovative affinity tools. Recent advances of affinity tool developments are described, both in a medical setting (e.g. diagnostics, therapeutics and drug delivery) and in several niche areas for which antibodies appear to be less attractive. Furthermore, an outlook is provided on anticipated future developments.
Photoemission spectroscopy study of oxygen spectrum and the chemical failure process of Alq3-based light-emitting devices
Authors: Wang Min-Shuai , Li Wan-Cheng , Ma Yan , Chang Yu-Chun , Guan He-Song , Wu Guo-Guang , Xun Fei-Lin , Gao Fu-Bin , Cheng Chuan-Hui , Du Guo-Tong
Published: May 2011

Tris (8-hydroxyquinolino) aluminum (Alq3) films and their chemical failure process are investigated using x-ray photoelectron spectroscopy. We make sure that the O 1s spectrum of the pristine Alq3 only has one component which is in contrast to the current controversy on this issue. Our experiments further indicate that the chemical failure process of Alq3 holds the critical role to understand this problem. The chemical failure process also shows the organic carbon contamination and the replacement reaction between Alq3 and water, ultimately resulted in the failure of the device. These fundamental results provide a basis understanding for future development of Alq3-based light emitting devices.
Blob motion and control in simple magnetized plasmas
Authors: Theiler C. , Furno I. , Fasoli A. , Ricci P. , Labit B. , Iraji D.
Published: May 2011

The radial propagation of plasma blobs and possibilities of influencing it are investigated in the TORPEX toroidal experiment [Fasoli et al., Phys. Plasmas 13, 055902 (2006)]. The effect of changing the connection length and the neutral background pressure on blob velocity is measured and trends are found to agree with predictions from a previous study [Theiler et al., Phys. Rev. Lett. 103, 065001, (2009)]. Effects on blob motion due to a change in limiter material and geometry are also discussed.
Investigation of a line-focused acoustic levitation for contactless transport of particles
Authors: Foresti Daniele , Bjelobrk Nada , Nabavi Majid , Poulikakos Dimos
Published: May 2011

We investigate herein an interesting acoustic line-focused levitation mechanism, enabling the simultaneous transportation of the acoustically levitated particles. It is shown that the performance of such a system is strongly dependent on the envelope of geometric parameters of the levitator. To study this dependence systematically, a thorough numerical model using the finite element method is developed. Both rigid and flexural radiating plates are considered. The effect of all important geometric parameters on the resulting acoustic potential patterns is investigated. After successful experimental validation, in which particles of density ca. 1000 times higher than that of their surrounding gas (∼1 g/cm3 versus ∼10−3 g/cm3) are levitated and translated, the model proves to be reliable in predicting the position as well as the force exerted on the levitated particles.
Kinetics of nickel silicide growth in silicon nanowires: From linear to square root growth
Authors: Yaish Y. E. , Katsman A. , Cohen G. M. , Beregovsky M.
Published: May 2011

The common practice for nickel silicide formation in silicon nanowires (SiNWs) relies on axial growth of silicide along the wire that is initiated from nickel reservoirs at the source and drain contacts. In the present work the silicide intrusions were studied for various parameters including wire diameter (25–50 nm), annealing time (15–120 s), annealing temperature (300–440∘C), and the quality of the initial Ni/Si interface. The silicide formation was investigated by high-resolution scanning electron microscopy, high-resolution transmission electron microscopy (TEM), and atomic force microscopy. The main part of the intrusion formed at 420∘C consists of monosilicide NiSi, as was confirmed by energy dispersive spectroscopy STEM, selected area diffraction TEM, and electrical resistance measurements of fully silicided SiNWs. The kinetics of nickel silicide axial growth in the SiNWs was analyzed in the framework of a diffusion model through constrictions. The model calculates the time dependence of the intrusion length, L, and predicts crossover from linear to square root time dependency for different wire parameters, as confirmed by the experimental data.
Green GaInN photonic-crystal light-emitting diodes with small surface recombination effect
Authors: Kitagawa Hitoshi , Fujita Masayuki , Suto Toshihide , Asano Takashi , Noda Susumu
Published: May 2011

We have fabricated green GaInN light-emitting diodes (LEDs) containing two-dimensional photonic crystals (PCs). The PC structure is comprised of air holes that penetrate through the active layer. The observed emission intensity at room temperature was enhanced by a factor of ∼3 when a PC was introduced, which is close to the theoretical enhancement calculated without taking into account surface recombination at the air-hole edges. The carrier lifetime changes little when a PC is incorporated due to the low surface recombination. In contrast, the carrier lifetime in blue-emitting LEDs decreased by a factor of 4 when a PC was introduced. The surface-recombination velocity in green-emitting devices is estimated to be 3×102 cm/s, an order of magnitude smaller than in blue-emitting devices. This is due to the strong carrier localization effect in green-emitting GaInN.
Strain dependence of electron-phonon energy loss rate in many-valley semiconductors
Authors: Muhonen J. T. , Prest M. J. , Prunnila M. , Gunnarsson D. , Shah V. A. , Dobbie A. , Myronov M. , Morris R. J. H. , Whall T. E. , Parker E. H. C. , Leadley D. R.
Published: May 2011

We demonstrate significant modification of the electron-phonon energy loss rate in a many-valley semiconductor system due to lattice mismatch induced strain. We show that the thermal conductance from the electron system to the phonon bath in strained n+Si, at phonon temperatures between 200 and 480 mK, is more than an order of magnitude lower than that for a similar unstrained sample.
Design strategies for mitigating the influence of polarization effects on GaN-based multiple quantum well light-emitting diodes
Authors: Lu H. M. , Chen G. X.
Published: May 2011

The optoelectronic properties of GaN-based multiple quantum well (MQW) light-emitting diodes (LEDs) are investigated using a detailed theoretical model, in which the effects of strain, well coupling, valence band mixing, and polarization effects are fully considered. By solving the conduction and valence band effective mass equations together with Poisson’s equation self-consistently, the influence of various major design parameters, such as the well width, the barrier components, and the barrier thickness, on the electronic and optical properties of GaN-based MQW LEDs is studied. Numerical results show that the emission spectra of the LEDs are very sensitive to the above design parameters due to the polarization effect that is unique for GaN-based devices. Further analysis and simulations reveal that this sensitivity can be obviously suppressed by choosing InGaN as the barrier material.
Organic-inorganic hybrid tandem multijunction photovoltaics with extended spectral response
Authors: Kim Taehee , Jeon Jun Hong , Han Seunghee , Lee Doh-Kwon , Kim Honggon , Lee Wonmok , Kim Kyungkon
Published: May 2011

We demonstrate series-connected hybrid tandem multijunction photovoltaics by combining hydrogenated amorphous silicon (a-Si:H) and polymer-based organic photovoltaics (OPVs). To utilize the wide solar spectrum with cost-effective processes, we employed a solution-processed low band gap OPV subcell onto the a-Si:H subcell. The interfacial contact between the subcells strongly affects the photovoltaic performance of the tandem cells. By using MoO3 as an efficient hole transporting intermediate layer instead of the conventional conducting polymer, we obtained power conversion efficiency of 1.84% and open-circuit voltage (VOC) of 1.50 V which corresponds closely to the sum of VOCs of the subcells.
Metal-induced gap states modeling of metal-Ge contacts with and without a silicon nitride ultrathin interfacial layer
Authors: Wager John F. , Robertson John
Published: May 2011

Metal-induced gap states (MIGS) modeling is used to elucidate the lack of Fermi level pinning at metal-insulator−Ge interfaces. Energy band diagram assessment reveals the existence of two dipoles at the metal-insulator and the insulator−semiconductor interface. The metal−insulator dipole modulates the metal-insulator interface electron barrier and the voltage drop across the insulator but does not affect the barrier to electron transport across the metal-insulator−Ge interface. Rather, this electron transport barrier is established by the metal-semiconductor work function difference and the insulator−semiconductor dipole. Thus, the lack of Fermi level pinning at a metal-insulator−Ge interface is attributed to the fact that the electron transport barrier does not depend upon MIGS screening. A quantitative formulation of this metal-insulator−semiconductor interface MIGS-based model confirms the lack of Fermi level pinning. Furthermore, it indicates that care must be taken when assessing experimental barrier height- work function data since the slope parameter should only be evaluated for the range of metal work function in which the semiconductor is in depletion. This range of work function for which the semiconductor is in depletion is quite limited for the case of a narrow bandgap semiconductor, such as Ge.
Phosphorus and boron diffusion gettering of iron in monocrystalline silicon
Authors: Talvitie H. , Vähänissi V. , Haarahiltunen A. , Yli-Koski M. , Savin H.
Published: May 2011

We have studied experimentally the phosphorus diffusion gettering (PDG) of iron in monocrystalline silicon at the temperature range of 650–800 °C. Our results fill the lack of data at low temperatures so that we can obtain a reliable segregation coefficient for iron between a phosphorus diffused layer and bulk silicon. The improved segregation coefficient is verified by time dependent PDG simulations. Comparison of the PDG to boron diffusion gettering (BDG) in the same temperature range shows PDG to be only slightly more effective than BDG. In general, we found that BDG requires more carefully designed processing conditions than PDG to reach a high gettering efficiency.
Nano-sized light emitting diodes by near field laser exposure
Authors: Intonti Francesca , Matarazzo Vitantonio , Nasir Ateeq , Makarovsky Oleg , Campion Richard , Patanè Amalia , Kumar Santosh , Rastelli Armando , Schmidt Oliver G. , Gurioli Massimo
Published: May 2011

We report a postfabrication process for the realization of nanosized light emitting diodes. The method is based on the exposure of the device to an Ar+ laser through an aperture near field optical microscope and can produce a large (>100 fold) increase in the electroluminescence within a near field hot spot as small as 440 nm. A study of morphological, photoluminescence and electroluminescence properties highlights the interplay between oxidation, annealing, and ablation processes for various laser exposure conditions.
Spin wave hybridization via direct mapping of spin wave evolution in ferromagnetic microstructures
Authors: Bai Lihui , Gui Y. S. , Chen Z. H. , Shen S. C. , Nitta Junsaku , Hu C.-M. , Hayward L. E. , Wismayer M. P. , Southern B. W.
Published: May 2011

Confined spin waves in single magnetic microstrips are investigated using a microwave photovoltage technique. Direct mapping of the spin wave evolution between surface, edge, and central modes is achieved by tuning the direction of the applied magnetic field. Both theoretical and numerical methods are used to study the evolution of the excitations and provide excellent agreement with the experimental results. The most prominent feature observed is a mode repulsing behavior which indicates mode hybridization in the dipole dominated part of the spin wave spectrum.
Synthesis of graphene on gold
Authors: Oznuluer Tuba , Pince Ercag , Polat Emre O. , Balci Osman , Salihoglu Omer , Kocabas Coskun
Published: May 2011

Here we report chemical vapor deposition of graphene on gold surface at ambient pressure. We studied effects of the growth temperature, pressure, and cooling process on the grown graphene layers. The Raman spectroscopy of the samples reveals the essential properties of the graphene grown on gold surface. In order to characterize the electrical properties of the grown graphene layers, we have transferred them on insulating substrates and fabricated field effect transistors. Owing to distinctive properties of gold, the ability to grow graphene layers on gold surface could open new applications of graphene in electrochemistry and spectroscopy.
Impact of bottom electrode and SrxTiyOz film formation on physical and electrical properties of metal-insulator-metal capacitors
Authors: Pawlak M. A. , Kaczer B. , Kim M.-S. , Popovici M. , Swerts J. , Wang W.-C. , Opsomer K. , Favia P. , Tomida K. , Belmonte A. , Govoreanu B. , Vrancken C. , Demeurisse C. , Bender H. , Afanas’ev V. V. , Debusschere I. , Altimime L. , Kittl J. A.
Published: May 2011

Metal-insulator-metal capacitors with SrxTiyOz (STO) dielectric films on TiN, Ru, and RuOx bottom electrodes with TiN top electrodes were studied. Metastable perovskite STO films with compositions in the Sr/(Sr+Ti)∼54–64 at. % range were obtained by crystallization at 600 °C in N2 of dielectric stacks grown by atomic layer deposition consisting of Sr-rich STO films [Sr/(Sr+Ti)∼64 at. %] on thin interfacial TiOx layers. The significant decrease in equivalent oxide thickness (EOT) and STO lattice parameter observed with increasing TiOx thickness indicates full intermixing of the TiOx and STO layers during the crystallization anneal, which results in the formation of an STO layer with higher Ti content and higher dielectric constant. The Sr-rich STO on TiOx stacks crystallize with small grain size, favorable for low leakage (JG). A significant improvement in JG for e-injection from the bottom electrode is obtained when using RuOx, as compared to TiN or Ru. A milder JG improvement with RuOx bottom electrode is also seen for e-injection from the top TiN electrode, indicating that higher quality perovskite STO films are formed on RuOx, or equivalently, that their trap density is lower. We propose oxygen scavenging from the STO by TiN or Ru electrodes, eliminated or reversed when using RuOx, as an explanation for the improvement. Using an optimized RuOx/TiOx/STO/TiN stack we obtained leakage of 10−7 A/cm2 (at 0.8 V) and 0.4 nm EOT.
Self-frequency-doubling of ultrafast laser inscribed neodymium doped yttrium aluminum borate waveguides
Authors: Dong Ningning , Martínez de Mendivil J. , Cantelar E. , Lifante G. , Vázquez de Aldana J. , Torchia G. A. , Chen Feng , Jaque Daniel
Published: May 2011

Buried channel optical waveguides, supporting orthogonal polarizations, have been fabricated in a neodymium doped yttrium aluminum borate nonlinear laser crystal by ultrafast laser inscription following the so-called “double line” approach. Confocal fluorescence and second harmonic imaging experiments have revealed that the original fluorescence and nonlinear properties have been not deteriorated by the waveguide inscription procedure. Preliminary laser experiments have shown the ability of the fabricated structures for green laser light generation under 808 nm optical pumping by self-frequency-doubling of the 1.06 μm laser line of neodymium ions.
Surface leakage current reduction in long wavelength infrared type-II InAs/GaSb superlattice photodiodes
Authors: Bogdanov S. , Nguyen B.-M. , Hoang A. M. , Razeghi M.
Published: May 2011

Dielectric passivation of long wavelength infrared type-II InAs/GaSb superlattice photodetectors with different active region doping profiles has been studied. SiO2 passivation was shown to be efficient as long as it was not put in direct contact with the highly doped superlattice. A hybrid graded doping profile combined with the shallow etch technique reduced the surface leakage current in SiO2 passivated devices by up to two orders of magnitude compared to the usual design. As a result, at 77 K the SiO2 passivated devices with 10.5 μm cutoff wavelength exhibit an R0A of 120 Ω cm2, RmaxA of 6000 Ω cm2, and a dark current level of 3.5×10−5 A cm−2 at −50 mV bias.
Local stress induced by diamond-like carbon liner in AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors and impact on electrical characteristics
Authors: Liu Xinke , Liu Bin , Low Edwin Kim Fong , Liu Wei , Yang Mingchu , Tan Leng-Seow , Teo Kie Leong , Yeo Yee-Chia
Published: May 2011

The device physics of AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistor (MOS-HEMT) with localized stress introduced by a diamond-like carbon (DLC) liner or encapsulation layer was investigated. DLC film with high intrinsic compressive stress (∼6 GPa) formed over AlGaN/GaN MOS-HEMTs contributed local compressive stress in the channel region. This was found to reduce the two-dimensional electron gas (2-DEG) density in the channel, leading to a positive threshold voltage shift. Transconductance and drain current at a given gate overdrive were also improved. On the other hand, the DLC introduced local tensile stress in the region between the gate and source/drain contacts, leading to a localized increase in 2-DEG density, giving reduced series resistance. The results of this work are expected to be useful for strain engineering of AlGaN/GaN MOS-HEMTs.
The depolarization of Pb(Zr0.52Ti0.48)O3 ferroelectrics by cylindrical radially expanding shock waves and its utilization for miniature pulsed power
Authors: Shkuratov Sergey I. , Baird Jason , Talantsev Evgueni F.
Published: May 2011

The effects of depolarization of Pb(Zr0.52Ti0.48)O3 (PZT 52/48) poled ferroelectrics by cylindrical radially expanding shock waves propagated along and across the polarization vector P0 were experimentally detected. Miniature (total volume 100 cm3) autonomous generators based on these effects were capable of producing output voltage pulses with amplitudes up to 25 kV and output energies exceeding 1 J.
Coaxial atomic force microscope probes for imaging with dielectrophoresis
Authors: Brown Keith A. , Berezovsky Jesse , Westervelt R. M.
Published: May 2011

We demonstrate atomic force microscope (AFM) imaging using dielectrophoresis (DEP) with coaxial probes. DEP provides force contrast allowing coaxial probes to image with enhanced spatial resolution. We model a coaxial probe as an electric dipole to provide analytic formulas for DEP between a dipole, dielectric spheres, and a dielectric substrate. AFM images taken of dielectric spheres with and without an applied electric field show the disappearance of artifacts when imaging with DEP. Quantitative agreement between our model and experiment shows that we are imaging with DEP.
Ultimate photovoltage in perovskite oxide heterostructures with critical film thickness
Authors: Wang Cong , Jin Kui-juan , Zhao Rui-qiang , Lu Hui-bin , Guo Hai-zhong , Ge Chen , He Meng , Wang Can , Yang Guo-zhen
Published: May 2011

One order larger photovoltage is obtained with critical thicknesses of La0.9Sr0.1MnO3 films in both kinds of heterostructures of La0.9Sr0.1MnO3/SrTiO3 (0.8 wt % Nb-doped) and La0.9Sr0.1MnO3/Si fabricated at various oxygen pressures. Our self-consistent calculation reveals that the critical thickness of the La0.9Sr0.1MnO3 film with the ultimate value of photovoltage is just the thickness of the depletion layer of La0.9Sr0.1MnO3 in both heterojunctions, respectively.
Highly p-doped epitaxial graphene obtained by fluorine intercalation
Authors: Walter Andrew L. , Jeon Ki-Joon , Bostwick Aaron , Speck Florian , Ostler Markus , Seyller Thomas , Moreschini Luca , Kim Yong Su , Chang Young Jun , Horn Karsten , Rotenberg Eli
Published: May 2011

We present a method for decoupling epitaxial graphene grown on SiC(0001) by intercalation of a layer of fluorine at the interface. The fluorine atoms do not enter into a covalent bond with graphene but rather saturate the substrate Si bonds. This configuration of the fluorine atoms induces a remarkably large hole density of p≈4.5×1013 cm−2, equivalent to the location of the Fermi level at 0.79 eV above the Dirac point ED.
First-principles studies on magnetic properties of rocksalt structure MC (M=Ca, Sr, and Ba) under pressure
Authors: Dong Shengjie , Zhao Hui
Published: May 2011

Magnetic properties of sp-electron half-metallic ferromagnets (HMFs) MC (M=Ca, Sr, and Ba) in rocksalt structure at ambient and elevated pressure have been investigated using first-principles within the generalized gradient approximation in the scheme of Perdew et al. [Phys. Rev. Lett. 77, 3865 (1996)]. Magnetic moments, lattice constants, and total energies are calculated as a function of external pressure. The calculations predict the occurrence of pressure-induced magnetic phase transitions and find that the main reason for the magnetic transitions of sp-electron HMFs is the band widening of anion p states.
Coulomb versus drag effects in a photoelectron bunch for extreme ultraviolet laser spectroscopy
Authors: Bleiner Davide , Balmer Jürg
Published: May 2011

Coulomb effects in an extreme ultraviolet laser-induced photoelectron bunch for spectroscopy were investigated computationally. Post-photoemission alteration of the trajectory, due to Coulombic interactions, hampers an accurate angle-resolved photoelectron spectroscopy. Simulations however demonstrated that operation in the redundant-population regime produces a drag-confined bunch, detached from a boundary sheath that experiences losses. Drastic reduction in the photoelectron density can loosen bunch-confinement and proportionally increase the boundary losses. Our simulations led to a critical number of photoelectrons per spot size equal to 1.5×104 e−/mm2.
Beneficial effect of CH foam coating on x-ray emission from laser-irradiated high-Z material
Authors: Xu Yan , Zhu Tuo , Li Shuanggui , Yang Jiamin
Published: May 2011

Laser-irradiated Au layer with CH foam coating is investigated numerically. It is found that when coated with under-critical density CH foam more thermal radiation is produced, while less radiation is produced when coated with over-critical density CH foam. The under-critical density CH foam coating, which is heated supersonically and volumetrically by lasers, hampers the expansion of high-Z plasma and helps increase the density and temperature of Au plasma in the radiation zone. It is a practical and simple way to increase the laser x-ray conversion efficiency of hohlraum by coated with low-Z foam of under-critical density. This idea is tested with an experiment in an analogous geometry. The line emission from laser-irradiated Ti layer coated with CH foam was measured, and the increment of x-ray when coated with under-critical density CH foam was found.
The
Arabidopsis thaliana
Med25 mediator subunit integrates environmental cues to control plant development
Authors: Elfving Nils , Davoine Céline , Benlloch Reyes , Blomberg Jeanette , Brännström Kristoffer , Müller Dörte , Nilsson Anders , Ulfstedt Mikael , Ronne Hans , Wingsle Gunnar , Nilsson Ove , Björklund Stefan
Published: May 2011

Development in plants is controlled by abiotic environmental cues such as day length, light quality, temperature, drought, and salinity. These signals are sensed by a variety of systems and transmitted by different signal transduction pathways. Ultimately, these pathways are integrated to control expression of specific target genes, which encode proteins that regulate development and differentiation. The molecular mechanisms for such integration have remained elusive. We here show that a linear 130-amino-acids-long sequence in the Med25 subunit of the
Arabidopsis thaliana
Mediator is a common target for the drought response element binding protein 2A, zinc finger homeodomain 1, and Myb-like transcription factors which are involved in different stress response pathways. In addition, our results show that Med25 together with drought response element binding protein 2A also function in repression of PhyB-mediated light signaling and thus integrate signals from different regulatory pathways.
Unexpected patterns of fisheries collapse in the world's oceans
Authors: Pinsky Malin L. , Jensen Olaf P. , Ricard Daniel , Palumbi Stephen R.
Published: May 2011

Understanding which species are most vulnerable to human impacts is a prerequisite for designing effective conservation strategies. Surveys of terrestrial species have suggested that large-bodied species and top predators are the most at risk, and it is commonly assumed that such patterns also apply in the ocean. However, there has been no global test of this hypothesis in the sea. We analyzed two fisheries datasets (stock assessments and landings) to determine the life-history traits of species that have suffered dramatic population collapses. Contrary to expectations, our data suggest that up to twice as many fisheries for small, low trophic-level species have collapsed compared with those for large predators. These patterns contrast with those on land, suggesting fundamental differences in the ways that industrial fisheries and land conversion affect natural communities. Even temporary collapses of small, low trophic-level fishes can have ecosystem-wide impacts by reducing food supply to larger fish, seabirds, and marine mammals.
Gold nanorods 3D-supercrystals as surface enhanced Raman scattering spectroscopy substrates for the rapid detection of scrambled prions
Authors: Alvarez-Puebla Ramón A. , Agarwal Ashish , Manna Pramit , Khanal Bishnu P. , Aldeanueva-Potel Paula , Carbó-Argibay Enrique , Pazos-Pérez Nicolas , Vigderman Leonid , Zubarev Eugene R. , Kotov Nicholas A. , Liz-Marzán Luis M.
Published: May 2011

Highly organized supercrystals of Au nanorods with plasmonic antennae enhancement of electrical field have made possible fast direct detection of prions in complex biological media such as serum and blood. The nearly perfect three-dimensional organization of nanorods render these systems excellent surface enhanced Raman scattering spectroscopy substrates with uniform electric field enhancement, leading to reproducibly high enhancement factor in the desirable spectral range.
Combining high biodiversity with high yields in tropical agroforests
Authors: Clough Yann , Barkmann Jan , Juhrbandt Jana , Kessler Michael , Wanger Thomas Cherico , Anshary Alam , Buchori Damayanti , Cicuzza Daniele , Darras Kevin , Putra Dadang Dwi , Erasmi Stefan , Pitopang Ramadhanil , Schmidt Carsten , Schulze Christian H. , Seidel Dominik , Steffan-Dewenter Ingolf , Stenchly Kathrin , Vidal Stefan , Weist Maria , Wielgoss Arno Christian , Tscharntke Teja
Published: May 2011

Local and landscape-scale agricultural intensification is a major driver of global biodiversity loss. Controversially discussed solutions include wildlife-friendly farming or combining high-intensity farming with land-sparing for nature. Here, we integrate biodiversity and crop productivity data for smallholder cacao in Indonesia to exemplify for tropical agroforests that there is little relationship between yield and biodiversity under current management, opening substantial opportunities for wildlife-friendly management. Species richness of trees, fungi, invertebrates, and vertebrates did not decrease with yield. Moderate shade, adequate labor, and input level can be combined with a complex habitat structure to provide high biodiversity as well as high yields. Although livelihood impacts are held up as a major obstacle for wildlife-friendly farming in the tropics, our results suggest that in some situations, agroforests can be designed to optimize both biodiversity and crop production benefits without adding pressure to convert natural habitat to farmland.
The hummingbird tongue is a fluid trap, not a capillary tube
Authors: Rico-Guevara Alejandro , Rubega Margaret A.
Published: May 2011

Hummingbird tongues pick up a liquid, calorie-dense food that cannot be grasped, a physical challenge that has long inspired the study of nectar-transport mechanics. Existing biophysical models predict optimal hummingbird foraging on the basis of equations that assume that fluid rises through the tongue in the same way as through capillary tubes. We demonstrate that the hummingbird tongue does not function like a pair of tiny, static tubes drawing up floral nectar via capillary action. Instead, we show that the tongue tip is a dynamic liquid-trapping device that changes configuration and shape dramatically as it moves in and out of fluids. We also show that the tongue–fluid interactions are identical in both living and dead birds, demonstrating that this mechanism is a function of the tongue structure itself, and therefore highly efficient because no energy expenditure by the bird is required to drive the opening and closing of the trap. Our results rule out previous conclusions from capillarity-based models of nectar feeding and highlight the necessity of developing a new biophysical model for nectar intake in hummingbirds. Our findings have ramifications for the study of feeding mechanics in other nectarivorous birds, and for the understanding of the evolution of nectarivory in general. We propose a conceptual mechanical explanation for this unique fluid-trapping capacity, with far-reaching practical applications (e.g., biomimetics).
Interdicting protease-activated receptor-2-driven inflammation with cell-penetrating pepducins
Authors: Sevigny Leila M. , Zhang Ping , Bohm Andrew , Lazarides Katherine , Perides George , Covic Lidija , Kuliopulos Athan
Published: May 2011

Protease-activated receptor-2 (PAR2), a cell surface receptor for trypsin-like proteases, plays a key role in a number of acute and chronic inflammatory diseases of the joints, lungs, brain, gastrointestinal tract, and vascular systems. Despite considerable effort by the pharmaceutical industry, PAR2 has proven recalcitrant to targeting by small molecule inhibitors, which have been unable to effectively prevent the interaction of the protease-generated tethered ligand with the body of the receptor. Here, we report the development of first-in-class cell-penetrating lipopeptide “pepducin” antagonists of PAR2. The design of the third intracellular (i3) loop pepducins were based on a structural model of a PAR2 dimer and by mutating key pharmacophores in the receptor intracellular loops and analogous pepducins. Individual pharmacophores were identified, which controlled constitutive, agonist, and antagonist activities. This approach culminated in the identification of the P2pal-18S pepducin which completely suppressed trypsin and mast cell tryptase signaling through PAR2 in neutrophils and colon cancer cells. The PAR2 pepducin was highly efficacious in blocking PAR2-dependent inflammatory responses in mouse models. These effects were lost in PAR2-deficient and mast-cell–deficient mice, thereby validating the specificity of the pepducin in vivo. These data provide proof of concept that PAR2 pepducin antagonists may afford effective treatments of potentially debilitating inflammatory diseases and serve as a blueprint for developing highly potent and specific i3-loop–based pepducins for other G protein-coupled receptors (GPCRs).
Architecture, sedentism, and social complexity at Pre-Pottery Neolithic A WF16, Southern Jordan
Authors: Finlayson Bill , Mithen Steven J. , Najjar Mohammad , Smith Sam , Maričević Darko , Pankhurst Nick , Yeomans Lisa
Published: May 2011

Recent excavations at Pre-Pottery Neolithic A (PPNA) WF16 in southern Jordan have revealed remarkable evidence of architectural developments in the early Neolithic. This sheds light on both special purpose structures and “domestic” settlement, allowing fresh insights into the development of increasingly sedentary communities and the social systems they supported. The development of sedentary communities is a central part of the Neolithic process in Southwest Asia. Architecture and ideas of homes and households have been important to the debate, although there has also been considerable discussion on the role of communal buildings and the organization of early sedentarizing communities since the discovery of the tower at Jericho. Recently, the focus has been on either northern Levantine PPNA sites, such as Jerf el Ahmar, or the emergence of ritual buildings in the Pre-Pottery Neolithic B of the southern Levant. Much of the debate revolves around a division between what is interpreted as domestic space, contrasted with “special purpose” buildings. Our recent evidence allows a fresh examination of the nature of early Neolithic communities.
Activity-dependent targeting of TRPV1 with a pore-permeating capsaicin analog
Authors: Li Hui , Wang Shu , Chuang Alexander Y. , Cohen Bruce E. , Chuang Huai-hu
Published: May 2011

The capsaicin receptor TRPV1 is the principal transduction channel for nociception. Excessive TRPV1 activation causes pathological pain. Ideal pain mangement requires selective inhibition of hyperactive pain-sensing neurons, but sparing normal nociception. We sought to determine whether it is possible to use activity-dependent TRPV1 agonists to identify nerves with excessive TRPV1 activity, as well as exploit the TRPV1 pore to deliver charged anesthetics for neuronal silencing. We synthesized a series of permanently charged capsaicinoids and found that one, cap-ET, efficaciously evoked TRPV1-dependent entry of Ca
2+
or the large cationic dye YO-PRO-1 comparably to capsaicin, but far smaller electrical currents. Cap-ET–induced YO-PRO-1 transport required permeation of both the agonist and the dye through the TRPV1 pore and could be enhanced by kinase activation or oxidative covalent modification. Moreover, cap-ET reduced capsaicin-induced currents by a voltage-dependent block of the pore. A low dose of cap-ET elicited entry of permanently charged Na
+
channel blockers to effectively suppress Na
+
currents in sensory neurons presensitized with oxidative chemicals. These results implicate therapeutic potential of these unique TRPV1 agonists exhibiting activity-dependent ion transport but of minimal pain-producing risks.
Bispecific digoxigenin-binding antibodies for targeted payload delivery
Authors: Metz Silke , Haas Alexander K. , Daub Karin , Croasdale Rebecca , Stracke Jan , Lau Wilma , Georges Guy , Josel Hans-Peter , Dziadek Sebastian , Hopfner Karl-Peter , Lammens Alfred , Scheuer Werner , Hoffmann Eike , Mundigl Olaf , Brinkmann Ulrich
Published: May 2011

Bispecific antibodies that bind cell-surface targets as well as digoxigenin (Dig) were generated for targeted payload delivery. Targeting moieties are IgGs that bind the tumor antigens Her2, IGF1R, CD22, or LeY. A Dig-binding single-chain Fv was attached in disulfide-stabilized form to C termini of CH3 domains of targeting antibodies. Bispecific molecules were expressed in mammalian cells and purified in the same manner as unmodified IgGs. They are stable without aggregation propensity and retain binding specificity/affinity to cell-surface antigens and Dig. Digoxigeninylated payloads were generated that retain full functionality and can be complexed to bispecific antibodies in a defined 2∶1 ratio. Payloads include small compounds (Dig-Cy5, Dig-Doxorubicin) and proteins (Dig-GFP). Complexed payloads are targeted by the bispecifics to cancer cells and because these complexes are stable in serum, they can be applied for targeted delivery. Because Dig bispecifics also effectively capture digoxigeninylated compounds under physiological conditions, separate administration of uncharged Dig bispecifics followed by application of Dig payload is sufficient to achieve antibody-mediated targeting in vitro and in vivo.
Transducin-like enhancer protein 1 mediates estrogen receptor binding and transcriptional activity in breast cancer cells
Authors: Holmes Kelly A. , Hurtado Antoni , Brown Gordon D. , Launchbury Rosalind , Ross-Innes Caryn S. , Hadfield James , Odom Duncan T. , Carroll Jason S.
Published: May 2011

Estrogen receptor (ER) binds to distal enhancers within the genome and requires additional factors, such as the Forkhead protein FoxA1, for mediating chromatin interactions. We now show that the human Groucho protein, Transducin-like enhancer protein 1 (TLE1), positively assists some ER-chromatin interactions, a role that is distinct from its general role as a transcriptional repressor. We show that specific silencing of TLE1 inhibits the ability of ER to bind to a subset of ER binding sites within the genome, a phenomenon that results in perturbations in phospho-RNA Pol II recruitment. Furthermore, TLE1 is essential for effective ER-mediated cell division. We have discovered a distinct role for TLE1, as a necessary transcriptional component of the ER complex, where it facilitates ER-chromatin interactions.
Obligate biotrophy features unraveled by the genomic analysis of rust fungi
Authors: Duplessis Sébastien , Cuomo Christina A. , Lin Yao-Cheng , Aerts Andrea , Tisserant Emilie , Veneault-Fourrey Claire , Joly David L. , Hacquard Stéphane , Amselem Joëlle , Cantarel Brandi L. , Chiu Readman , Coutinho Pedro M. , Feau Nicolas , Field Matthew , Frey Pascal , Gelhaye Eric , Goldberg Jonathan , Grabherr Manfred G. , Kodira Chinnappa D. , Kohler Annegret , Kües Ursula , Lindquist Erika A. , Lucas Susan M. , Mago Rohit , Mauceli Evan , Morin Emmanuelle , Murat Claude , Pangilinan Jasmyn L. , Park Robert , Pearson Matthew , Quesneville Hadi , Rouhier Nicolas , Sakthikumar Sharadha , Salamov Asaf A. , Schmutz Jeremy , Selles Benjamin , Shapiro Harris , Tanguay Philippe , Tuskan Gerald A. , Henrissat Bernard , Van de Peer Yves , Rouzé Pierre , Ellis Jeffrey G. , Dodds Peter N. , Schein Jacqueline E. , Zhong Shaobin , Hamelin Richard C. , Grigoriev Igor V. , Szabo Les J. , Martin Francis
Published: May 2011

Rust fungi are some of the most devastating pathogens of crop plants. They are obligate biotrophs, which extract nutrients only from living plant tissues and cannot grow apart from their hosts. Their lifestyle has slowed the dissection of molecular mechanisms underlying host invasion and avoidance or suppression of plant innate immunity. We sequenced the 101-Mb genome of
Melampsora larici
-
populina
, the causal agent of poplar leaf rust, and the 89-Mb genome of
Puccinia graminis
f. sp.
tritici
, the causal agent of wheat and barley stem rust. We then compared the 16,399 predicted proteins of
M. larici-populina
with the 17,773 predicted proteins of
P. graminis
f. sp
tritici
. Genomic features related to their obligate biotrophic lifestyle include expanded lineage-specific gene families, a large repertoire of effector-like small secreted proteins, impaired nitrogen and sulfur assimilation pathways, and expanded families of amino acid and oligopeptide membrane transporters. The dramatic up-regulation of transcripts coding for small secreted proteins, secreted hydrolytic enzymes, and transporters
in planta
suggests that they play a role in host infection and nutrient acquisition. Some of these genomic hallmarks are mirrored in the genomes of other microbial eukaryotes that have independently evolved to infect plants, indicating convergent adaptation to a biotrophic existence inside plant cells.
Assessing climate change impacts on the near-term stability of the wind energy resource over the United States
Authors: Pryor S. C. , Barthelmie R. J.
Published: May 2011

The energy sector comprises approximately two-thirds of global total greenhouse gas emissions. For this and other reasons, renewable energy resources including wind power are being increasingly harnessed to provide electricity generation potential with negligible emissions of carbon dioxide. The wind energy resource is naturally a function of the climate system because the “fuel” is the incident wind speed and thus is determined by the atmospheric circulation. Some recent articles have reported historical declines in measured near-surface wind speeds, leading some to question the continued viability of the wind energy industry. Here we briefly articulate the challenges inherent in accurately quantifying and attributing historical tendencies and making robust projections of likely future wind resources. We then analyze simulations from the current generation of regional climate models and show, at least for the next 50 years, the wind resource in the regions of greatest wind energy penetration will not move beyond the historical envelope of variability. Thus this work suggests that the wind energy industry can, and will, continue to make a contribution to electricity provision in these regions for at least the next several decades.
Whole-Teflon microfluidic chips
Authors: Ren Kangning , Dai Wen , Zhou Jianhua , Su Jing , Wu Hongkai
Published: May 2011

Although microfluidics has shown exciting potential, its broad applications are significantly limited by drawbacks of the materials used to make them. In this work, we present a convenient strategy for fabricating whole-Teflon microfluidic chips with integrated valves that show outstanding inertness to various chemicals and extreme resistance against all solvents. Compared with other microfluidic materials [e.g., poly(dimethylsiloxane) (PDMS)] the whole-Teflon chip has a few more advantages, such as no absorption of small molecules, little adsorption of biomolecules onto channel walls, and no leaching of residue molecules from the material bulk into the solution in the channel. Various biological cells have been cultured in the whole-Teflon channel. Adherent cells can attach to the channel bottom, spread, and proliferate well in the channels (with similar proliferation rate to the cells in PDMS channels with the same dimensions). The moderately good gas permeability of the Teflon materials makes it suitable to culture cells inside the microchannels for a long time.
Fluctuating and sensory-induced vasodynamics in rodent cortex extend arteriole capacity
Authors: Drew Patrick J. , Shih Andy Y. , Kleinfeld David
Published: May 2011

Neural activity in the brain is followed by localized changes in blood flow and volume. We address the relative change in volume for arteriole vs. venous blood within primary vibrissa cortex of awake, head-fixed mice. Two-photon laser-scanning microscopy was used to measure spontaneous and sensory evoked changes in flow and volume at the level of single vessels. We find that arterioles exhibit slow (<1 Hz) spontaneous increases in their diameter, as well as pronounced dilation in response to both punctate and prolonged stimulation of the contralateral vibrissae. In contrast, venules dilate only in response to prolonged stimulation. We conclude that stimulation that occurs on the time scale of natural stimuli leads to a net increase in the reservoir of arteriole blood. Thus, a “bagpipe” model that highlights arteriole dilation should augment the current “balloon” model of venous distension in the interpretation of fMRI images.