bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma diagnostics of low pressure high power impulse magnetron sputtering assisted by electron cyclotron wave resonance plasma
Authors: Stranak Vitezslav , Herrendorf Ann-Pierra , Drache Steffen , Cada Martin , Hubicka Zdenek , Bogdanowicz Robert , Tichy Milan , Hippler Rainer
Published: November 2012

This paper reports on an investigation of the hybrid pulsed sputtering source based on the combination of electron cyclotron wave resonance (ECWR) inductively coupled plasma and high power impulse magnetron sputtering (HiPIMS) of a Ti target. The plasma source, operated in an Ar atmosphere at a very low pressure of 0.03 Pa, provides plasma where the major fraction of sputtered particles is ionized. It was found that ECWR assistance increases the electron temperature during the HiPIMS pulse. The discharge current and electron density can achieve their stable maximum 10 μs after the onset of the HiPIMS pulse. Further, a high concentration of double charged Ti++ with energies of up to 160 eV was detected. All of these facts were verified experimentally by time-resolved emission spectroscopy, retarding field analyzer measurement, Langmuir probe, and energy-resolved mass spectrometry.
Wave resonances and the partition of energy in ideal compressible magnetohydrodynamic fluids
Authors: Zorzan C. , Cally P. S.
Published: November 2012

Phase mixing and resonant absorption are two processes that have been under scrutiny for some time because of their role in wave damping and in providing a mechanism for heating space and laboratory plasmas. The accumulation or absorption of energy that develops within a resonant layer is usually attributed to a logarithmic singularity, but it will be shown that this build up of energy is inextricably tied to a discontinuity in the fluid displacement at the resonant point. This change in the dynamics of the problem will be examined by establishing a partition of energy that identifies and isolates the individual resonances within the fluid. The partition is based on a variational description of the Fourier transformed equations and is guided by an electrical model of the MHD system that not only illustrates the resonant structure threading the fluid but also exposes the mechanism driving the resonant absorption process. A simplified version of this model is then constructed to help determine the approximate rate of energy absorption.
Frictional properties of two alkanethiol self assembled monolayers in sliding contact: Odd-even effects
Authors: Ramin Leyla , Jabbarzadeh Ahmad
Published: November 2012

Using molecular dynamics simulation, we have investigated the structural effects on the frictional properties of self assembled monolayers (SAM) of n-alkanethiols [CH3(CH2)n-1SH, n = 12–15] in SAM-SAM contacts attached on Au (111) substrates. We have observed an odd-even effect where friction coefficient for SAM-SAM contacts with n = odd showed consistently higher values than those with n = even. This odd-even effect is independent of the sliding velocity and the relative tilt directions of the SAMs, and persists over a much higher pressure range than that reported before for SAM-Au contacts [L. Ramin and A. Jabbarzadeh, Langmuir 28, 4102−4112 (2012)10.1021/la204701z]. For odd systems higher gauche defects were shown to be the possible source of high friction coefficient. Under the same load and shear rates (comparable sliding velocities), SAM-SAM contacts show mostly higher friction compared to SAM-Au contacts. For SAM-SAM contacts, a more significant increase of friction occurs at higher shear rates due to a shift in the tilt orientation angle. We show SAM-SAM contacts with misaligned relative tilt orientation angle (∼45°–90°) have considerably lower friction compared with those whose tilt orientation angles are almost aligned in the opposite directions and parallel to the shear.
Enhancement of charge transport in DNA molecules induced by the next nearest-neighbor effects
Authors: Malakooti Sadeq , Hedin Eric R. , Kim Young D. , Joe Yong S.
Published: November 2012

An advanced two-dimensional tight-binding model including the next nearest-neighbor effects for quantum mechanical electron transport through double-stranded DNA molecules is proposed. Considering the next nearest-neighbor hopping strengths between sites gives a more rational and realistic model for the electron path-way through DNA molecules. We show higher overall transmission and enhanced current for a 30 base-pair poly(G)–poly(C) DNA molecule with the inclusion of diagonal electron hopping between the sites. In addition, an optimum condition of the contact hopping strength and Fermi energy to obtain the maximum current for the system is demonstrated. Finally, we present the current-voltage characteristics showing a transition from a semiconductor-like to a metal-like DNA molecule with the variation of the Fermi energy.
High optical polarization ratio of semipolar (202¯1¯)-oriented InGaN/GaN quantum wells and comparison with experiment
Authors: Park Seoung-Hwan , Ahn Doyeol
Published: November 2012

Optical anisotropy properties of (202¯1¯)-plane wurtzite (WZ) InGaN/GaN quantum well (QW) structures were investigated using the multiband effective-mass theory and the non-Markovian model with many-body effects. The results were compared with those of non-polar (112¯0) a-plane InGaN/GaN QW structures. The In content dependence of the transition wavelength of the (202¯1¯)-plane QW structure is found to be very similar to that of (112¯0)-plane QW structure. The (202¯1¯)-plane shows slightly smaller y′-polarized spontaneous emission coefficient than that with the (112¯0)-plane. On the other hand, in the case of x′-polarization, the (202¯1¯)-plane QW structure has a larger spontaneous emission coefficient than the (112¯0)-plane QW structure. The in-plane optical anisotropies of both QW structures are shown to increase gradually with increasing transition wavelength or In content. The optical anisotropy of (202¯1¯)-oriented QW structure is ranging from 0.50 at 400 nm to 0.75 at 530 nm, which is in good agreement with the experimental result.
Broadband Brewster transmission through 2D metallic gratings
Authors: Le Khai Q. , Argyropoulos Christos , Mattiucci Nadia , D'Aguanno Giuseppe , Bloemer Mark J. , Alù Andrea
Published: November 2012

Recently, we have introduced a mechanism to achieve ultrabroadband light funnelling and total transmission through 1D narrow metallic gratings at a specific incidence angle, the so-called plasmonic Brewster angle. This phenomenon is based on impedance matching between the guided modes supported by ultranarrow linear slits and transverse-magnetic waves at oblique incidence. In this paper, we demonstrate that such phenomenon, representing the equivalent of Brewster transmission for plasmonic screens, can also occur in 2D metallic gratings of various structural forms and shapes, and that it may be made insensitive to the azimuthal, or polarization, angle φ. This finding may have relevant implications to realize large funneling, absorption and squeezing of light in perforated metallic screens.
Diffusion thermopower in suspended graphene: Effect of strain
Authors: Vaidya R. G. , Sankeshwar N. S. , Mulimani B. G.
Published: November 2012

Diffusion thermopower, Sd, is studied in pure suspended graphene (SG) monolayers in equipartition regime (for 100 K < T < 300 K). Electrons are considered to be scattered by the intrinsic in-plane and out-of-plane flexural acoustic phonons. Our numerical calculations of the temperature, T and carrier concentration, ns, dependences of electron mobility and Sd bring out the relative importance of the two scattering mechanisms in SG in the presence and absence of strain. For free-standing SG, Sd is found to vary almost linearly with temperature with dominant contribution from flexural phonons. This contribution is found to be suppressed in strained SG resulting in enhancement in mobility and reduction in Sd. Dependences of mobility and Sd on T and ns are modified. The relevance of Nordheim-Gorter rule in SG is also studied.
Actuation abilities of multiphasic electroactive polymeric systems
Authors: Lallart Mickaël , Capsal Jean-Fabien , Mossi Idrissa Abdoul Kader , Galineau Jérémy , Kanda Masae , Guyomar Daniel
Published: November 2012

The need of low-cost, high-strain actuators has recently brought the attention on electroactive polymers. Specifically, a particular interest has been placed on dielectric-based electrostrictive polymers that are flexible, conformable, and with an easy manufacturing process. The purpose of this paper is to investigate the actuation abilities of such devices when several phases (i.e., dipolar and interfacial) contribute to the electroactive strain response. Based on a Debye-Langevin approach, the expression of each phase contribution will be investigated, and the response with several phase ratios discussed. In particular, it is shown that a trade-off exists between low electric-field response, where the main design parameter lies in the permittivity, and the high electric-field response, where a polarization saturation effect occurs that limits the electric-generated strain. In addition, it is shown both theoretically and experimentally that for a biphasic system, a particular crossing point appears in the strain response as a function of the electric field whatever the phase ratio, as well as in the frequency-domain electrical response.
Ge/SrTiO3(001): Correlation between interface chemistry and crystallographic orientation
Authors: Gobaut B. , Penuelas J. , Grenet G. , Ferrah D. , Benamrouche A. , Chettaoui A. , Robach Y. , Botella C. , El Kazzi M. , Silly M. G. , Sirotti F. , Saint-Girons G.
Published: November 2012

In this work, the desorption of a submonolayer deposit of Ge on SrTiO3(001) is studied by reflection high energy electron diffraction. The results are compared to those of a previous experiment done using soft x-ray photoelectron spectroscopy. Combining these techniques allows for correlating interface chemistry and crystal orientation, and for bringing clarifying elements concerning the competition between (111) and (001) crystal orientation typical for the semiconductor/perovskite epitaxial systems. Despite poor interface matching, (111)-oriented islands are stabilized at the expense of (001)-oriented islands due to the relatively low energy of their free facets. Such “surface energy driven” crystallographic orientation of the deposit is enhanced by the low adhesion energy characteristic of the Ge/SrTiO3 system.
Spectroscopic refractometer for transparent and absorbing liquids by reflection of white light near the critical angle
Authors: Sánchez-Pérez C. , García-Valenzuela A.
Published: November 2012

We propose and evaluate a spectroscopic refractometer device to measure the refractive index dispersion of transparent and absorbing solutions. The angle-dependent reflectivity of a white beam of light in an internal reflection configuration around the critical angle is spectrally analyzed. The refractive index in a wavelength range from 400 nm to 900 nm is obtained from the angle-reflectivity curve around the critical angle at each wavelength. The device does not use angle scanning mechanisms, decreasing considerably the complexity of the instrument in comparison to previous proposals. As a result, the measurements are obtained relatively fast. Nevertheless, a good experimental resolution in refractive index of about Δn ≈ 10−4 at all the wavelengths is achieved in the case of transparent solutions. The calibration procedure of the device is discussed in detail. We also present measurements of the refractive index dispersion of rhodamine 6G-methanol solutions, which has a strong absorption band in the visible spectra.
Photoluminescence and light reabsorption in SiC quantum dots embedded in binary-polyelectrolyte solid matrix
Authors: Zhang Nan , Dai Dejian , Zhang Wenxia , Fan Jiyang
Published: November 2012

We report photoluminescence (PL) and light reabsorption in the SiC quantum dots (QDs) embedded in the binary poly(allylamine hydrochloride)-sodium poly(styrene sulfonate) polyelectrolytes solid matrix. The emission maximum wavelength can be tuned over a wide blue-violet spectral region indicating a PL origin of quantum confinement. The emission maximum exhibits a red shift with increasing concentration of the QDs in the polyelectrolytes matrix. The analysis shows that this shift stems from reabsorption of PL of smaller SiC QDs by larger ones in the matrix. We find that deposition of Ag nanoparticles on the surface of the solid matrix can dramatically reduce light reabsorption owing to surface plasmon-induced concentration of incident light. Additionally, the PL intensity was enhanced by a factor of 1.4. Our results open the possibility of the SiC QDs-based solid blue-UV light emitters for applications in full-solid-state lighting and display.
Defect assistant band alignment transition from staggered to broken gap in mixed As/Sb tunnel field effect transistor heterostructure
Authors: Zhu Y. , Jain N. , Vijayaraghavan S. , Mohata D. K. , Datta S. , Lubyshev D. , Fastenau J. M. , Liu Amy K. , Monsegue N. , Hudait M. K.
Published: November 2012

The compositional dependence of effective tunneling barrier height (Ebeff) and defect assisted band alignment transition from staggered gap to broken gap in GaAsSb/InGaAs n-channel tunnel field effect transistor (TFET) structures were demonstrated by x-ray photoelectron spectroscopy (XPS). High-resolution x-ray diffraction measurements revealed that the active layers are internally lattice matched. The evolution of defect properties was evaluated using cross-sectional transmission electron microscopy. The defect density at the source/channel heterointerface was controlled by changing the interface properties during growth. By increasing indium (In) and antimony (Sb) alloy compositions from 65% to 70% in InxGa1−xAs and 60% to 65% in GaAs1−ySby layers, the Ebeff was reduced from 0.30 eV to 0.21 eV, respectively, with the low defect density at the source/channel heterointerface. The transfer characteristics of the fabricated TFET device with an Ebeff of 0.21 eV show 2× improvement in ON-state current compared to the device with Ebeff of 0.30 eV. On contrary, the value of Ebeff was decreased from 0.21 eV to −0.03 eV due to the presence of high defect density at the GaAs0.35Sb0.65/In0.7Ga0.3As heterointerface. As a result, the band alignment was converted from staggered gap to broken gap, which leads to 4 orders of magnitude increase in OFF-state leakage current. Therefore, a high quality source/channel interface with a properly selected Ebeff and well maintained low defect density is necessary to obtain both high ON-state current and low OFF-state leakage in a mixed As/Sb TFET structure for high-performance and lower-power logic applications.
Optical and structural properties of SiOx films grown by molecular beam deposition: Effect of the Si concentration and annealing temperature
Authors: Nikitin Timur , Velagapudi Rama , Sainio Jani , Lahtinen Jouko , Räsänen Markku , Novikov Sergei , Khriachtchev Leonid
Published: November 2012

We study the properties of Si-rich silicon oxide SiOx (x < 2) films grown on silica substrates by molecular beam deposition, in a wide range of Si content and annealing temperatures. The measured refractive index and absorption coefficient are successfully described using the effective medium approximation and the chemical compositions measured by x-ray photoelectron spectroscopy (XPS). The Si–SiO2 phase separation and the degree of Si crystallization increase with the annealing temperature; however, even after annealing at 1200 °C, the samples contain a large proportion of suboxides and partially disordered Si. The Si Raman signal and the absorption coefficient are nearly proportional to the amount of elemental Si provided by XPS. On the other hand, the Si Raman signal is much weaker than it is expected from the amount of elemental Si, which can be explained by the presence of ultra-small Si nanocrystals (diameters < 2 nm) and/or by the difference in the properties of bulk and nanoscale Si. The 1.5-eV photoluminescence (PL) intensity is the highest for annealing at 1100–1150 °C and x = 1.8–1.9. In contrast, the PL quantum yield steadily increases when the intensity of the Si Raman signal decreases. This observation suggests that the Si nanocrystals observed in the Raman spectra are not direct light-emitting centers. The temperatures induced by laser light in these films are surprisingly high, especially at the highest Si content (x ∼ 1.3). The laser-induced temperature (up to ∼350 °C) substantially down-shifts the Raman band of Si nanocrystals (in our experiments from ∼518 to ∼512 cm−1) and increases the absorption coefficient (by a factor of ∼1.4).
Phonons and superconductivity in the cubic perovskite Cr3RhN
Authors: Tütüncü H. M. , Srivastava G. P.
Published: November 2012

We have performed an ab initio study of structural, electronic, vibrational, and superconducting properties of Cr3RhN. The calculations have been carried out by employing the density functional theory, a linear-response formalism, and the plane-wave pseudopotential method. A striking feature of the phonon spectra in this cubic perovskite is the existence of a number of soft modes at the zone centre as well as at Brillouin zone boundaries. Calculations of the Eliashberg spectral function α2F(ω) and the electron-phonon prefactor α2(ω) reveal that the low frequency soft phonon branches couple more strongly with electrons. Using the calculated electron-phonon coupling parameter λ=1.03 and the logarithmically averaged frequency ωln=255 K, we suggest that this material is a superconductor with the transition temperature close to 17 K.
Monodisperse alginate microgel formation in a three-dimensional microfluidic droplet generator
Authors: Lian Meng , Collier C. Patrick , Doktycz Mitchel J. , Retterer Scott T.
Published: November 2012

Droplet based microfluidic systems provide an ideal platform for partitioning and manipulating aqueous samples for analysis. Identifying stable operating conditions under which droplets are generated is challenging yet crucial for real-world applications. A novel three-dimensional microfluidic platform that facilitates the consistent generation and gelation of alginate-calcium hydrogel microbeads for microbial encapsulation, over a broad range of input pressures, in the absence of surfactants is described. The unique three-dimensional design of the fluidic network utilizes a height difference at the junction between the aqueous sample injection and organic carrier channels to induce droplet formation via a surface tension enhanced self-shearing mechanism. Combined within a flow-focusing geometry, under constant pressure control, this arrangement facilitates predictable generation of droplets over a much broader range of operating conditions than that of conventional two-dimensional systems. The impact of operating pressures and geometry on droplet gelation, aqueous and organic material flow rates, microbead size, and bead generation frequency are described. The system presented provides a robust platform for encapsulating single microbes in complex mixtures into individual hydrogel beads, and provides the foundation for the development of a complete system for sorting and analyzing microbes at the single cell level.
Resistive switching in hafnium dioxide layers: Local phenomenon at grain boundaries
Authors: Lanza M. , Bersuker G. , Porti M. , Miranda E. , Nafría M. , Aymerich X.
Published: November 2012

Overcoming challenges associated with implementation of resistive random access memory technology for non-volatile information storage requires identifying the material characteristics responsible for resistive switching. In order to connect the switching phenomenon to the nano-scale morphological features of the dielectrics employed in memory cells, we applied the enhanced conductive atomic force microscopy technique for in situ analysis of the simultaneously collected electrical and topographical data on HfO2 stacks of various degrees of crystallinity. We demonstrate that the resistive switching is a local phenomenon associated with the formation of a conductive filament with a sufficiently small cross-section, which is determined by the maximum passing current. Switchable filament is found to be formed at the dielectric sites where the forming voltages were sufficiently small, which, in the case of the stoichiometric HfO2, is observed exclusively at the grain boundary regions representing low resistant conductive paths through the dielectric film.
The dynamic mechanism of a moving Crookes radiometer
Authors: Chen Songze , Xu Kun , Lee Cunbiao
Published: November 2012

The dynamics of a 2D rotating Crookes radiometer is studied using a moving mesh unified gas kinetic scheme. The whole evolution process of a fan from an initial unsteady start-up to a final steady state rotational movement in a rarefied gas environment is simulated numerically. Through the numerical study, the unsteady force distribution along a vane which dynamically drives the fan movement is captured. And a quantitative connection between total torque and rotational speed of the fan in the Knudsen number regime of 10−3 < Kn < 102 is obtained. Based on the dimensional analysis, the total radiometric torque can be decomposed into a net radiometric driving torque and a rotational resistance. Based on the numerical data, the analytical functions of the torque and angular velocity of a rotating fan in terms of Knudsen number are quantitatively constructed. This relationship is used to explain the experimental observation of the Knudsen number shift for the appearance of the maximum torque and the maximum rotational speed in the transitional flow regime.
Dopant mapping of Be δ-doped layers in GaAs tailored by counterdoping using scanning tunneling microscopy
Authors: Ebert Ph. , Landrock S. , Chiu Y. P. , Breuer U. , Dunin-Borkowski R. E.
Published: November 2012

The effect of counterdoping on the Be dopant distribution in delta (δ)-doped layers embedded in Si-doped and intrinsic GaAs is investigated by cross-sectional scanning tunneling microscopy. δ-doped layers in intrinsic GaAs exhibit a large spreading, whereas those surrounded by Si-doped GaAs remain spatially localized. The different spreading is explained by the Fermi-level pinning at the growth surface, which leads to an increased Ga vacancies concentration with increasing Si counterdoping. The Ga vacancies act as sinks for the diffusing Be dopant atoms, hence retarding the spreading.
Power management strategies and energy storage needs to increase the operability of photovoltaic plants
Authors: Beltran H. , Etxeberria-Otadui I. , Belenguer E. , Rodriguez P.
Published: November 2012

This paper analyzes the effect of introducing an energy storage (ES) system in an intermittent renewable energy power plant such as a photovoltaic (PV) installation. The aim of this integration is to achieve an improvement in the operability of these power plants by increasing their production predictability. This will allow a further PV integration within the electrical power system, facilitating the system's load–demand balance. In this manner, the paper proposes two power management strategies (PMSs), each with different configurations, for operating a PV power plant: the first focuses on fixing constant power production and the latter focuses on reducing the high frequency fluctuations of the production. Thereafter, this paper analyzes and quantifies the ratings of the ES system (ESS) required to ensure a reliable performance of the plant on an annual basis for each of the PMSs with their different possible configurations. The resulting ES ratings vary with these PMS configurations. It can be concluded that significant improvements in production predictability are achieved with an ESS energy capacity of approximately 50% of the average daily energy produced by the PV panels and a power rating of around 55% of the plant's rated power. All the results are based on 1-year-long simulations which used real irradiance data sampled every 2 min.
Sub-bandgap spectral photo-response analysis of Ti supersaturated Si
Authors: García-Hemme E. , García-Hernansanz R. , Olea J. , Pastor D. , del Prado A. , Mártil I. , Gónzalez-Díaz G.
Published: November 2012

We have analyzed the increase of the sheet conductance (ΔG□) under spectral illumination in high dose Ti implanted Si samples subsequently processed by pulsed-laser melting. Samples with Ti concentration clearly above the insulator-metal transition limit show a remarkably high ΔG□, even higher than that measured in a silicon reference sample. This increase in the ΔG□ magnitude is contrary to the classic understanding of recombination centers action and supports the lifetime recovery predicted for concentrations of deep levels above the insulator-metal transition.
Correlating macroscopic and nanoscale electrical modifications of SiO2/4H-SiC interfaces upon post-oxidation-annealing in N2O and POCl3
Authors: Swanson L. K. , Fiorenza P. , Giannazzo F. , Frazzetto A. , Roccaforte F.
Published: November 2012

This letter reports on the electrical properties of SiO2/4H-SiC interfaces after post-oxidation annealing (POA) in N2O and POCl3. The notably higher channel mobility measured in 4H-SiC MOSFETs subjected to POA in POCl3 was ascribed both to a reduction of the interface traps density and to an increase of donor concentration incorporated in SiC. Scanning spreading resistance microscopy on a SiC surface directly exposed to POA revealed that the incorporation of P-related shallow donors upon POA in POCl3 is more efficient than N-shallow donors incorporation during N2O treatments which subsequently explains the significantly enhanced channel conductivity of the MOSFETs.
A biomimetic mechanism for antibody immobilization on lipid nanofibers for cell capture
Authors: Zha Zhengbao , Jiang Linan , Dai Zhifei , Wu Xiaoyi
Published: November 2012

The immobilization of membrane-bound molecules on organic-inorganic cholesteryl-succinyl silane (CSS) nanofibers is investigated. Fluorescent microscopy and a cell capture assay confirm the stable and functional immobilization of membrane-bound antibodies and imaging agents on the electrospun CSS nanofibers. An insert-and-tighten mechanism is proposed for the observed hydration-induced reduction in lipid nanofiber diameter, the immobilization of membrane-bound molecules, and the improved efficiency of cell capture by the functionalized CSS nanofibers over their film counterparts. The ability to stably and functionally immobilize membrane-bound molecules on the CSS nanofibers presents a promising method to functionalize lipid-based nanomaterials.
The Jahn-Teller effect in the electron momentum spectroscopy of ammonia
Authors: Zhu J. S. , Miao Y. R. , Deng J. K. , Ning C. G.
Published: November 2012

The 1e and 3a1 bands of the ammonia molecule have been studied using the high-resolution electron momentum spectroscopy at impact energies of 1200 and 600 eV. Several slices of 1e and 3a1 bands in the different binding energy ranges were selected, and their electron-momentum distributions were carefully compared. The discernable difference among the distributions of the selected slices of the 1e band shows that the Jahn-Teller effect indeed influences the electron momentum distribution of the 1e orbital of ammonia.
Fast photo-switchable surfaces for boiling heat transfer applications
Authors: Hunter C. N. , Turner D. B. , Jespersen M. L. , Check M. H. , Borton P. T. , Glavin N. R. , Voevodin A. A.
Published: November 2012

Several milligrams of the ruthenium-centered organometallic complex, ruthenium bis-4,4′-di(thiomethyl)-2,2′-bipyridine, mono-2 -(2-pyridyl)-1,3-oxathiane ([Ru{(HS-CH2)2-bpy}2{pox}](PF6)2) were synthesized and used to produce a self assembled monolayer film on a gold substrate. X-ray photoelectron spectroscopy analysis of the film detected the presence of bound thiolate, which is an indication of a chemisorbed film. Water contact angle measurements were performed before and after 5 min of visible light irradiation using an ozone-free 1000 W Xe(Hg) arc source with a 425-680 nm long pass mirror. The contact angle changed from 52° pre-irradiation (hydrophilic state) to 95° post-irradiation (hydrophobic state).
Communication: An exact bound on the bridge function in integral equation theories
Authors: Kast Stefan M. , Tomazic Daniel
Published: November 2012

We show that the formal solution of the general closure relation occurring in Ornstein-Zernike-type integral equation theories in terms of the Lambert W function leads to an exact relation between the bridge function and correlation functions, most notably to an inequality that bounds possible bridge values. The analytical results are illustrated on the example of the Lennard-Jones fluid for which the exact bridge function is known from computer simulations under various conditions. The inequality has consequences for the development of bridge function models and rationalizes numerical convergence issues.
Nitrogen tolerance in the lichen Xanthoria parietina: the sensitive side of a resistant species
Authors: Munzi Silvana , Branquinho Cristina , Cruz Cristina , Loppi Stefano
Published: November 2012

To investigate the mechanisms of nitrogen (N) tolerance in lichens, we examined the physiological responses to increased N availability in different functional groups. Thalli of the nitrophytic Xanthoria parietina (L.) Th.Fr. previously grown both in an N-poor environment (~2 kg N ha–1 year–1) and in an N-rich environment (~52 kg N ha–1 year–1) were compared with the oligotrophic species Evernia prunastri (L.) Ach. and Usnea sp. Lichens were submitted to ammonium treatments. Maximum PSII efficiency, redistribution of the ions between the intra- and extracellular compartments and potassium and magnesium concentrations were the parameters used to check for the effects of N supply. The buffering capacity of the lichen extracts was also determined in untreated lichen thalli to check if different lichen behaviours were due to their ability to maintain the pH. The results showed a more similar response between X. parietina from the N-poor environment and the N-sensitive species than between X. parietina from the N-poor and N-rich environments, suggesting that X. parietina achieved N-tolerance after long-term exposure to N-rich environment. These results are important in understanding the effects of chronic ammonium pollution on one of the most sensitive components of the ecosystem, linking physiological response and ecological consequences.
RNA polymerase III subunit architecture and implications for open promoter complex formation
Authors: Wu Chih-Chien , Herzog Franz , Jennebach Stefan , Lin Yu-Chun , Pai Chih-Yu , Aebersold Ruedi , Cramer Patrick , Chen Hung-Ta
Published: November 2012

Transcription initiation by eukaryotic RNA polymerase (Pol) III relies on the TFIIE-related subcomplex C82/34/31. Here we combine cross-linking and hydroxyl radical probing to position the C82/34/31 subcomplex around the Pol III active center cleft. The extended winged helix (WH) domains 1 and 4 of C82 localize to the polymerase domains clamp head and clamp core, respectively, and the two WH domains of C34 span the polymerase cleft from the coiled-coil region of the clamp to the protrusion. The WH domains of C82 and C34 apparently cooperate with other mobile regions flanking the cleft during promoter DNA binding, opening, and loading. Together with published data, our results complete the subunit architecture of Pol III and indicate that all TFIIE-related components of eukaryotic and archaeal transcription systems adopt an evolutionarily conserved location in the upper part of the cleft that supports their functions in open promoter complex formation and stabilization.
STING manifests self DNA-dependent inflammatory disease
Authors: Ahn Jeonghyun , Gutman Delia , Saijo Shinobu , Barber Glen N.
Published: November 2012

Inflammatory autoimmune diseases such as systemic lupus erythematosus (SLE) and polyarthritis are characterized by chronic cytokine overproduction, suggesting that the stimulation of host innate immune responses, speculatively by persistent infection or self nucleic acids, plays a role in the manifestation of these disorders. Mice lacking DNase II die during embryonic development through comparable inflammatory disease because phagocytosed DNA from apoptotic cells cannot be adequately digested and intracellular host DNA sensor pathways are engaged, resulting in the production of a variety of cytokines including type I IFN. The cellular sensor pathway(s) responsible for triggering DNA-mediated inflammation aggravated autoimmune disease remains to be determined. However, we report here that Stimulator of IFN Genes (STING) is responsible for inflammation-related embryonic death in DNase II defective mice initiated by self DNA. DNase II-dependent embryonic lethality was rescued by loss of STING function, and polyarthritis completely prevented because cytosolic DNA failed to robustly trigger cytokine production through STING-controlled signaling pathways. Our data provides significant molecular insight into the causes of DNA-mediated inflammatory disorders and affords a target that could plausibly be therapeutically controlled to help prevent such diseases.
miR-495 is a tumor-suppressor microRNA down-regulated in
MLL
-rearranged leukemia
Authors: Jiang Xi , Huang Hao , Li Zejuan , He Chunjiang , Li Yuanyuan , Chen Ping , Gurbuxani Sandeep , Arnovitz Stephen , Hong Gia-Ming , Price Colles , Ren Haomin , Kunjamma Rejani B. , Neilly Mary Beth , Salat Justin , Wunderlich Mark , Slany Robert K. , Zhang Yanming , Larson Richard A. , Le Beau Michelle M. , Mulloy James C. , Rowley Janet D. , Chen Jianjun
Published: November 2012

Acute myeloid leukemia (AML) is a heterogeneous group of hematopoietic malignancies with variable response to treatment. AMLs bearing
MLL
(mixed lineage leukemia) rearrangements are associated with intermediate or poor survival. MicroRNAs (miRNAs), a class of small noncoding RNAs, have been postulated to be important gene expression regulators virtually in all biological processes, including leukemogenesis. Through a large-scale, genome-wide miRNA expression profiling assay of 85 human AML and 15 normal control samples, we show that among 48 miRNAs that are significantly differentially expressed between
MLL
- and non–
MLL
-rearranged AML samples, only one (miR-495) is expressed at a lower level in
MLL
-rearranged AML than in non–
MLL
-rearranged AML; meanwhile, miR-495 is also significantly down-regulated in
MLL
-rearranged AML samples compared with normal control samples. Through in vitro colony-forming/replating assays and in vivo bone marrow transplantation studies, we show that forced expression of miR-495 significantly inhibits MLL-fusion-mediated cell transformation in vitro and leukemogenesis in vivo. In human leukemic cells carrying
MLL
rearrangements, ectopic expression of miR-495 greatly inhibits cell viability and increases cell apoptosis. Furthermore, our studies demonstrate that
PBX3
and
MEIS1
are two direct target genes of miR-495, and forced expression of either of them can reverse the effects of miR-495 overexpression on inhibiting cell viability and promoting apoptosis of human
MLL
-rearranged leukemic cells. Thus, our data indicate that miR-495 likely functions as a tumor suppressor in AML with
MLL
rearrangements by targeting essential leukemia-related genes.
Sex at Length of Summer Flounder Landed in the New Jersey Recreational Party Boat Fishery
Authors: Morson Jason M. , Bochenek Eleanor A. , Powell Eric N. , Gius Jennifer E.
Published: November 2012

Female summer flounder Paralichthys dentatus grow faster than males and experience a lower natural mortality rate. Sex-structured assessment models have been developed for other fishes with sexually dimorphic characteristics to better account for population dynamics. Although a desire exists to develop similar assessment techniques for summer flounder, some prerequisite data are not available, including the sex of fish that are landed in the recreational fishery. Furthermore, summer flounder recreational landings are constrained within harvest limits almost entirely by minimum size restrictions—a management approach that could place much of the recreational fishing mortality on females. To fill a basic but important data requirement to improve the stock assessment of this species while also providing some insight on how current management strategies might impact the sex structure of the population, we collected data on sex and length of summer flounder (n = 4,437) that were landed in the New Jersey recreational fishery in 2009 and 2010. Females dominated the recreational catch in both years (95% female overall). The proportion of landed fish at a given length that were females was greater at lower latitudes and earlier in the summer; the proportion female at length was greater in 2010 than in 2009. Extensive seasonal, annual, and spatial variability evident over such a local scale suggests a highly dynamic sex dependency in the population dynamics of summer flounder and indicates that a more robust data set covering wider geographic and temporal scales will be necessary before sex-specific landings data can be confidently incorporated into an assessment.

Received February 20, 2012; accepted August 17, 2012
Waring’s problem for polynomials in two variables
Authors: Bodin Arnaud , Car Mireille
Published: November 2012

We prove that all polynomials in several variables can be decomposed as the sums ofkkth powers:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper P left-parenthesis x 1 comma ellipsis comma x Subscript n Baseline right-parenthesis equals upper Q 1 left-parenthesis x 1 comma ellipsis comma x Subscript n Baseline right-parenthesis Superscript k Baseline plus midline-horizontal-ellipsis plus upper Q Subscript s Baseline left-parenthesis x 1 comma ellipsis comma x Subscript n Baseline right-parenthesis Superscript k">P(x1,…,xn)=Q1(x1,…,xn)k+⋯+Qs(x1,…,xn)kP(x_1,\ldots ,x_n) = Q_1(x_1,\ldots ,x_n)^k+\cdots + Q_s(x_1,\ldots ,x_n)^k, provided that elements of the base field are themselves sums ofkkth powers. We also give bounds for the number of termsssand the degree of theQikQ_i^k. We then improve these bounds in the case of two-variable polynomials of large degree to get a decomposition<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper P left-parenthesis x comma y right-parenthesis equals upper Q 1 left-parenthesis x comma y right-parenthesis Superscript k Baseline plus midline-horizontal-ellipsis plus upper Q Subscript s Baseline left-parenthesis x comma y right-parenthesis Superscript k">P(x,y)=Q1(x,y)k+⋯+Qs(x,y)kP(x,y) = Q_1(x,y)^k+\cdots + Q_s(x,y)^kwithdeg⁡Qik⩽deg⁡P+k3\deg Q_i^k \leqslant \deg P + k^3andssthat depends onkkandln⁡(deg⁡P)\ln (\deg P).
Genetic polymorphisms confer risk of atrial fibrillation in patients with heart failure: a population‐based study
Authors: Smith J. Gustav , Melander Olle , Sjögren Marketa , Hedblad Bo , Engström Gunnar , Newton‐Cheh Christopher , Platonov Pyotr G.
Published: November 2012

Aims

Atrial fibrillation (AF) is a frequent co‐morbidity in heart failure (HF) associated with increased mortality, but little is known about the mechanisms underlying AF onset in HF patients. We evaluated the association of cardiovascular and genetic risk factors with AF in HF patients.

Methods and results

Individuals hospitalized for HF (n = 1040; 500 with AF) were identified from a large, population‐based cohort study (n = 30 447; 2339 with AF). Genetic polymorphisms in the chromosomal regions 4q25 (rs2200733) and 16q22 (rs2106261) associated with AF in genome‐wide association studies were genotyped. Association of cardiovascular risk factors and polymorphisms with AF was tested in HF patients and the entire cohort using both prospective and non‐time‐dependent models. Cardiovascular risk factors—hypertension, body mass index, sex, smoking, diabetes, and myocardial infarction—were associated with AF in the entire cohort but not in HF patients. In contrast, polymorphisms on chromosomes 16q22 and 4q25 were associated with AF both in the entire cohort and in HF patients, conferring 75% [95% confidence interval (CI) 35–126, P = 2 × 10−5] and 57% (95% CI 18–109, P = 0.002) increased risk of AF per copy in HF patients, respectively. In the entire cohort, AF risk in the presence of HF was multiplicatively magnified by genotype for 16q22 (P for interaction = 7 × 10−4) but not 4q25 (P = 0.83). In prospective analyses excluding patients with AF diagnosis prior to or simultaneously with HF diagnosis, 16q22 but not 4q25 remained robustly associated with AF (hazard ratio 1.96, 95% CI 1.40–2.73, P = 8 × 10−5). The proportion of AF diagnoses in HF patients attributable to polymorphisms was 19% and 12%, respectively.

Conclusions

A polymorphism in the ZFHX3 gene, encoding a cardiac transcription factor, was associated with increased AF risk in HF patients, and the genetic association with AF was more pronounced in HF patients than in the general population.
Death by Volcano: Revolutionary Theatre and Marie-Antoinette
Authors: Perovic Sanja
Published: November 2012

This paper compares the trial and execution of Marie-Antoinette on 16 October 1793 with the performance, two days later, of Sylvain Maréchal's hit play
Le Jugement dernier des rois
, which staged the death of all of Europe's monarchs by an exploding volcano. What links them is the revolutionary concept of rupture, in which the historical breach with the past, associated with the death of the king, was to have established a new temporal relation between events. This article contends that the continued existence of the queen
after
the symbolic act of regicide and the official beginning of a new time reflects a profound crisis in the revolutionary self-image, a crisis fictively resolved by Maréchal's utopian depiction of a world-historical revolution in which all of Europe's monarchs are naturally extinguished. For the volcano shows how revolutionary history requires the supplement of a symbolic terror in order to reintegrate events within a linear history of progress. By contextualizing the queen's trial within its own present, when revolutionary history was being actively constructed, this article aims to shed new light on the relation between revolutionary violence and the experience of time.
La Double Exigence éthique dans les Mémoires du duc de Saint-Simon
Authors: Pigozzo Francesco
Published: November 2012

Si le duc de Saint-Simon mémorialiste a été susceptible de critiques en tant qu'historien et idéologue, personne au fond n'a jamais pu douter de l'authenticité de son engagement éthique et passionnel, tel qu'on le connaît à travers les trente-deux années de sa chronique. Grâce à une approche originale de la question de la dimension littéraire des
Mémoires
, cet article se propose d'expliquer les raisons d'une telle discordance d'opinions. Une contradiction fondamentale hante et nourrit la manière saint-simonienne de concevoir, de juger et de représenter la réalité: dans presque chaque page du texte l'esprit normatif du duc cohabite et s'entremêle avec une véritable obsession des écarts. L'acception politique de l'ambiguïté qui en résulte est analysée en tant que source principale de la polysémie des
Mémoires
aussi bien que de leur vivante beauté. Une comparaison avec la réflexion de Max Weber sur les deux morales mondaines se révèle enfin un outil interprétatif essentiel pour éclairer la signification historique d'un texte qui n'a pas fini de nous instruire par sa capacité de nous surprendre.
Heart Failure
Authors: Harris Keara R , Thompson Mareike K
Published: November 2012

Heart failure has a prevalence of nearly 1% in the general population and is associated with age and other cardiovascular disease. It occurs when the heart is unable to maintain an adequate circulation for normal activity. This article explores the definition, diagnosis and impact of heart failure, and updates the reader on current national and international guidance on investigation and management.
Overview of Cardiomyopathy
Authors: Rogers Andrew , Loudon Margaret , Dwight Jeremy
Published: November 2012

‘Cardiomyopathy’ describes disease of the heart muscle. The European Society of Cardiology (ESC) defines cardiomyopathy as ‘a myocardial disorder in which the heart muscle is structurally and functionally abnormal in the absence of coronary artery disease, hypertension, valvular disease, and congenital heart disease sufficient to explain the observed myocardial abnormality’. In Europe, approximately 1 in 400 people suffer with some form of cardiomyopathy, and this is likely to be an underestimate due to a proportion of asymptomatic patients. Cardiomyopathy often has a strong genetic component. GPs are well placed to identify high-risk individuals due to their knowledge of a patient's family history. Cardiomyopathies are chronic conditions, and GPs are therefore central in the long-term management of these patients.
Thermomechanically Induced Protein Aggregation and Starch Structural Changes in Wheat Flour Dough
Authors: Rosell Cristina M. , Altamirano‐Fortoul Rossana , Don Clyde , Dubat Arnaud
Published: November 2012

Various studies have been carried out on wheat flour to understand protein and starch changes when subjected to mixing and temperature constraints, but structural changes of proteins and starch at the typical moisture levels of a dough system are not fully understood. The aim of this research was to improve our understanding of (micro)structural changes at the mesoscopic level, through empirical rheology, microscopy (light and scanning electron microscopy), sequential protein extractions, and glutenin macropolymer wet weight along the mixing, heating, and cooling stages of the Mixolab assay. Studies were performed on three wheat flours with different protein contents. The rheological analysis allowed identifying the role of the proteins and the relationship between the protein content and different primary and secondary parameters obtained from the recorded curves. The progressive heating and mixing stages during the Mixolab assay resulted in a dynamic de‐ and restructuring of proteins involving interactions between the flour proteins from water soluble to SDS soluble to SDS insoluble and vice versa. The microstructure analysis with light, polarized, and scanning electron microscopy revealed the changes that proteins and starch molecules underwent during mixing, heating, and cooling. Qualitatively, the starch structural changes, swelling, and gelatinization observed by microscopic techniques showed some parallels with protein (and glutenin) content of the respective flour. Nevertheless, this tentative finding needs further confirmation by studying flour samples with large differences in glutenin content.
A ClpB Chaperone Knockout Mutant of Mesorhizobium ciceri Shows a Delay in the Root Nodulation of Chickpea Plants
Authors: Brígido Clarisse , Robledo Marta , Menéndez Esther , Mateos Pedro F. , Oliveira Solange
Published: November 2012

Several molecular chaperones are known to be involved in bacteria stress response. To investigate the role of chaperone ClpB in rhizobia stress tolerance as well as in the rhizobia-plant symbiosis process, the clpB gene from a chickpea microsymbiont, strain Mesorhizobium ciceri LMS-1, was identified and a knockout mutant was obtained. The ClpB knockout mutant was tested to several abiotic stresses, showing that it was unable to grow after a heat shock and it was more sensitive to acid shock than the wild-type strain. A plant-growth assay performed to evaluate the symbiotic performance of the clpB mutant showed a higher proportion of ineffective root nodules obtained with the mutant than with the wild-type strain. Nodulation kinetics analysis showed a 6- to 8-day delay in nodule appearance in plants inoculated with the ΔclpB mutant. Analysis of nodC gene expression showed lower levels of transcript in the ΔclpB mutant strain. Analysis of histological sections of nodules formed by the clpB mutant showed that most of the nodules presented a low number of bacteroids. No differences in the root infection abilities of green fluorescent protein–tagged clpB mutant and wild-type strains were detected. To our knowledge, this is the first study that presents evidence of the involvement of the chaperone ClpB from rhizobia in the symbiotic nodulation process.