bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of prestrain on coherence length and order parameter
Authors: Yong Huadong , Xue Feng , Zhou Youhe
Published: December 2010

In this paper, an analytical method is presented for determining the effective coherence length and order parameter in a superconductor. The interaction of the deformations of the crystal lattice with the superconducting condensate is considered. A simplified free energy has been used in the literature to estimate the effect of the prestrain on the coherence length and the order parameter. The exact solutions for three dimensional and plane strain problems are obtained. Based on the linear elastic theory, an extensive analysis is made during the positive and negative prestrain for the isotropic material. The results show that the effect of the prestrain on the superconductivity is appreciable. A comparison is made between three dimensional and two dimensional results, and there is not significant difference between the results for two conditions. These explicit solutions provide a convenient tool for evaluating the superconductivity when the material undergoes the deformation.
Optimal control of magnetization dynamics in ferromagnetic heterostructures by spin-polarized currents
Authors: Wenin M. , Windisch A. , Pötz W.
Published: December 2010

We study the switching-process of the magnetization in a ferromagnetic-normal-metal multilayer system by a spin polarized electrical current via the spin transfer torque. We use a spin drift-diffusion equation (SDDE) and the Landau–Lifshitz–Gilbert equation (LLGE) to capture the coupled dynamics of the spin density and the magnetization dynamic of the heterostructure. Deriving a fully analytic solution of the stationary SDDE we obtain an accurate, robust, and fast self–consistent model for the spin–distribution and spin transfer torque inside general ferromagnetic/normal metal heterostructures. Using optimal control theory we explore the switching and back-switching process of the analyzer magnetization in a seven-layer system. Starting from a Gaussian, we identify a unified current pulse profile which accomplishes both processes within a specified switching time.
Ab initio calculations of structural, electronic, optical, and elastic properties of pure and Yb-doped InP at varying pressure
Authors: Brik M. G. , Kaminska A. , Suchocki A.
Published: December 2010

Results of ab initio calculations of structural, electronic, optical, and elastic properties of pure and Yb-doped InP at pressures between ambient and 10 GPa in the density functional theory framework, using the CASTEP module of Materials Studio 4.0, are reported. It is assumed (in agreement with the experiment) that in this range of pressures pure InP and InP:Yb crystallizes in space group F4¯3m with four formula unit in a unit cell. Obtained values of lattice constant, bulk modulus, and its pressure derivative are in good agreement with experimental values reported by different authors. Additional calculations of the overlap integrals between the ytterbium and phosphorus wave functions in the InP host confirm that the observed previously [Kaminska et al., Phys. Rev. B 81, 165209 (2010)] at pressure of above 6 GPa effect of limiting of increase in f–f intrashell transition energies with increased pressure is associated with the top of the valence band of InP crystal host approaching the energies of the f–f Yb transitions.
A total internal reflection fluorescence microscopy study of mass diffusion enhancement in water-based alumina nanofluids
Authors: Veilleux Jocelyn , Coulombe Sylvain
Published: December 2010

Mass diffusion of rhodamine 6G (R6G) in water-based alumina nanofluids is studied by means of total internal reflection fluorescence (TIRF) microscopy. We report a mass diffusivity enhancement that reaches an order of magnitude in a 2 vol % nanofluid when compared to the value in deionized water. Since experiments were performed with positively charged R6G, interfacial complexation between the dye and the nanoparticles was not observed. The effect of local density variations on mass diffusivity measurements is also addressed. An explanation for the enhancement of mass diffusion is presented using arguments based on dispersion, and it is shown that it correctly describes the order of magnitude differences between the thermal conductivity and mass diffusivity enhancements reported in the literature.
A method for emission cross section determination of Tm3+ at 2.0 μm emission
Authors: Zhang Liyan , Zhang Junjie , Yu Chunlei , Hu Lili
Published: December 2010

In the emission cross section (σemi) calculation of rare-earth ions (RE3+), two parameters, zero-line energy (Ezl) and partition function of lower and upper states (Zl/Zu), are very difficult to be determined. This induces large discrepancy of σemi value, especially for RE3+ with large Stokes shift such as Tm3+. Based on McCumber and Reciprocity theories, we present a transition model and propose a method for Ezl and Zl/Zu determinations of Tm3+ at 2.0 μm emission. Several Tm3+ doped glasses are investigated by this method. Influence of Tm3+ concentration and sample’s thickness to Ezl and Zl/Zu is also discussed. Results indicate that samples with thin thickness are preferred in Ezl determination as well as σemi calculation. Comparison of σemi values derived from F-L equation and our method demonstrates that accurate σemi value of Tm3+ can be obtained by this method. Since the established transition model is a universal one, then this method is suited to all RE3+ singly doped materials theoretically.
Tuning the electron injection barrier between Co and C60 using Alq3 buffer layer
Authors: Wang Yu-Zhan , Qi Dong-Chen , Chen Shi , Mao Hong-Ying , Wee Andrew T. S. , Gao Xing-Yu
Published: December 2010

We demonstrate that the electron injection barrier (Δe) between Co and C60 can be tuned by inserting a thin Alq3 interlayer. Using ultraviolet photoemission spectroscopy, Δe of C60 on Alq3-predecorated Co (Δe=0.3 eV) was found to be reduced by 0.3 eV compared with that of C60 deposited directly on the bare Co metal surface (Δe=0.6 eV). Due to Fermi level pining at the Alq3/Co interface, this tuning effect is independent of the thickness of Alq3 interlayer from multilayer to monolayer. Based on the experimental results, band level alignment diagrams are proposed for C60/Co and C60/Alq3/Co interfaces with two different Alq3 thicknesses. Our findings could have potential applications for the reduction in the carrier injection barrier in organic spin valves.
Properties of silver/porous-silicon nanocomposite powders prepared by metal assisted electroless chemical etching
Authors: Nakamura Toshihiro , Hosoya Naoki , Tiwari Bishnu P. , Adachi Sadao
Published: December 2010

We demonstrate that silver/porous-Si nanocomposite powders are obtained by etching Si powders with metal assisted electroless chemical reaction in an aqueous solution of AgNO3 and HF. From x-ray photoelectron spectroscopy and scanning electron microscope measurements, metal layer consisting of nanometer-sized Ag particles and their aggregates is formed on each Si powder surface. Immoderate etching at higher concentrations of AgNO3 results in the decrease in Si volume and increase in Ag layer thickness. Dips are observed in reflectance spectra of the nanocomposite powders at ∼400 nm. By comparing the experimental spectra with theoretically calculated ones, these dips are found to arise from the optical absorption due to the roughness-assisted surface plasmon excitation and to be dependent on the size of the Ag nanostructure. The nanocomposite powders show weaker photoluminescence intensity than that of conventionally stain-etched porous Si powders, however, their photostability is improved. The improvement of the photostability is considered to be due to the existence of surface Si–O and Si–Ag bonds.
Supersymmetry algebra cohomology. II. Primitive elements in 2 and 3 dimensions
Authors: Brandt Friedemann
Published: December 2010

The primitive elements of the supersymmetry algebra cohomology as defined in a companion paper are computed exhaustively for standard supersymmetry algebras in dimensions D = 2 and D = 3, for all signatures (t, D − t) and all numbers N of sets of supersymmetries.
Enhanced field emission from ZnO nanowires grown on a silicon nanoporous pillar array
Authors: Xu Hai Jun , Chan Yu Fei , Su Lei , Li De Yao , Sun Xiao Ming
Published: December 2010

A large scale heterostructure array of ZnO nanowires/silicon nanoporous pillar array (Si-NPA) was prepared by a self-catalytic thermal evaporation and vapor-phase transport method, and an ultrahigh field emission current density of 1.55 mA cm−2 was obtained under an operating electric field of 4.0 V μm−1, with a low turn-on field of 1.65 V μm−1. The enhancement factor calculated according to the Fowler–Nordheim theory was ∼3141. The excellent field emission performance was attributed to the unique structure of ZnO/Si-NPA, especially the formation of ZnO nanowires on regular Si pillar array. Our work indicated that ZnO/Si-NPA might be an ideal candidate cathode of potential applications in flat panel displays and high brightness electron sources.
Atomic-scale structure and electronic property of the LaAlO3/TiO2 interface
Authors: Wang Zhongchang , Zeng Wen , Gu Lin , Saito Mitsuhiro , Tsukimoto Susumu , Ikuhara Yuichi
Published: December 2010

Combining advanced transmission electron microscopy with high-precision first-principles calculation, atomic-scale structures of the LaAlO3/TiO2 interface are investigated and bridged to their electronic property at the atomic level. Experimentally, the deposited TiO2 thin film is demonstrated to have an anatase phase and bond directly to the LaAlO3 substrate in an epitaxial, coherent, and atomically abrupt fashion. The atomic-resolution microscopic images reveal that the interface can be terminated with either AlO2 or LaO layer, which is predicted in theory to exhibit a semiconducting or metallic nature at interface, respectively. By applying several analytic methods, we characterize carefully the electronic structure and determine interfacial bonding to be of a mixed covalent-ionic character. The combined experimental and theoretical studies performed shed light on the complex atomic and electronic structures of the buried interface, which are fundamental for understanding the promising properties of functional films for future electronics.
Onset of double-diffusive convection in a rectangular cavity with stress-free upper boundary
Authors: Chen Zhi-Wu , Zhan Jie-Min , Li Yok-Sheung , Nie Yu-Hua
Published: December 2010

Double-diffusive buoyancy convection in an open-top rectangular cavity with horizontal temperature and concentration gradients is considered. Attention is restricted to the case where the opposing thermal and solutal buoyancy effects are of equal magnitude (buoyancy ratio Rρ=−1). In this case, a quiescent equilibrium solution exists and can remain stable up to a critical thermal Grashof number Grc. Linear stability analysis and direct numerical simulation show that depending on the cavity aspect ratio A, the first primary instability can be oscillatory, while that in a closed cavity is always steady. Near a codimension-two point, the two leading real eigenvalues merge into a complex coalescence that later produces a supercritical Hopf bifurcation. As Gr further increases, this complex coalescence splits into two real eigenvalues again. The oscillatory flow consists of counter-rotating vortices traveling from right to left and there exists a critical aspect ratio below which the onset of convection is always oscillatory. Neutral stability curves showing the influences of A, Lewis number Le, and Prandtl number Pr are obtained. While the number of vortices increases as A decreases, the flow structure of the eigenfunction does not change qualitatively when Le or Pr is varied. The supercritical oscillatory flow later undergoes a period-doubling bifurcation and the new oscillatory flow soon becomes unstable at larger Gr. Random initial fields are used to start simulations and many different subcritical steady states are found. These steady states correspond to much stronger flows when compared to the oscillatory regime. The influence of Le on the onset of steady flows and the corresponding heat and mass transfer properties are also investigated.
Ion acoustic solitons in unmagnetized inhomogeneous multi-ion component plasmas with vortex distributed electrons
Authors: Shah Asif , Mahmood S. , Haque Q.
Published: December 2010

The ion acoustic solitons are studied in an inhomogeneous multi-ion component plasma in the presence of heavy and light adiabatic ions and two temperature electrons with vortex distribution. The modified Korteweg–de Vries equation with an additional term due to density gradients is derived by employing reductive perturbation technique. It is found that the amplitude of the soliton enhances as the concentration ratio of cold to hot electrons, density gradient parameter and ion temperature are increased in the system. The effects of mass, charge ratios of heavy to light ions and electron temperature are also investigated on the structural as well as propagation characteristics of solitary wave. The equilibrium density profile is taken to be exponential. The phase velocity of ion acoustic wave is also studied as a function of various plasma parameters. The numerical results are presented for illustration.
Dynamics and structure of decaying shallow dipolar vortices
Authors: Duran-Matute M. , Albagnac J. , Kamp L. P. J. , van Heijst G. J. F.
Published: December 2010

The current work reports on a numerical and experimental study of the evolution of decaying dipolar vortices in a shallow fluid layer. The dynamics and the structure of such vortices are investigated as a function of both their Reynolds number Re and the aspect ratio of vertical and horizontal length scales δ. By quantifying the strength of the secondary motions (vertical motions and nonzero horizontal divergence) with respect to the swirling motions of the primary vortex cores, it was found that the three-dimensionality of a shallow (δ⪡1) dipolar vortex only depends on a single parameter: δ2 Re. Depending on the value of this parameter, three flow regimes are observed for shallow dipolar vortices: (1) a quasi-two-dimensional regime where the structure of the dipolar vortex remains almost unchanged throughout its lifetime, (2) a transitional regime where the structure presents some three-dimensional characteristics but remains coherent, and (3) a three-dimensional regime where the structure of the dipolar vortex acquires a complicated three-dimensional shape with a persistent spanwise vortex at its front.
Terahertz conductivity of the metal-insulator transition in a nanogranular VO2 film
Authors: Cocker T. L. , Titova L. V. , Fourmaux S. , Bandulet H. -C. , Brassard D. , Kieffer J. -C. , El Khakani M. A. , Hegmann F. A.
Published: December 2010

Terahertz time-domain spectroscopy is used to measure the complex terahertz conductivity of a nanogranular vanadium dioxide (VO2) thin film as a function of temperature through the metal-insulator transition. The Drude–Smith model provides a good fit to the observed terahertz conductivity, revealing a metallic state that forms via switching of individual nanograins and strong carrier confinement within the nanograins due to scattering off grain boundaries. Furthermore, the directly applied Drude–Smith model provides a more accurate description of the measured terahertz conductivity in this material than either Bruggeman or Maxwell–Garnett effective medium theories.
Room temperature single-electron memory and light sensor with three-dimensionally positioned InAs quantum dots
Authors: Göpfert S. , Worschech L. , Lingemann S. , Schneider C. , Press D. , Höfling S. , Forchel A.
Published: December 2010

The authors report on the fabrication and characterization of single-electron memories based on site-controlled InAs quantum dots (QDs) embedded in a GaAs/AlGaAs quantum-wire transistor. By using a hole structure template on a modulation-doped GaAs/AlGaAs heterostructure in combination with etching techniques, two single InAs QDs were centrally positioned in a quantum-wire transistor so that pronounced shifts of the transistor threshold occur by charging of the QDs with single electrons. Single-electron read and write functionalities up to room temperature were observed. The memory function can be also controlled by light with a wavelength in the telecommunication range.
Probing the existence of energetically degenerate cluster isomers by chemical tagging
Authors: Wang Qian , Sun Qiang , Jena Puru
Published: December 2010

Current methods for identifying the ground state geometry of a cluster require synergy between theory and experiment. However, this becomes a difficult problem when the accuracy of the theoretical methods is not sufficient to distinguish between nearly degenerate isomers. Using density functional theory based calculations, we show that the near degeneracy between the planar and the cage structures can be lifted by tagging these with halogens and superhalogens moieties such as Cl and BO2. The energy of the planar Au16− isomer is lowered from 0.15 eV before tagging to 0.51–0.55 eV after tagging, thus providing a way to probe its coexistence.
Fabrication of p-channel thin-film transistors using CuO active layers deposited at low temperature
Authors: Sung Sang-Yun , Kim Se-Yun , Jo Kwang-Min , Lee Joon-Hyung , Kim Jeong-Joo , Kim Sang-Gon , Chai Kyoung-Hoon , Pearton S. J. , Norton D. P. , Heo Young-Woo
Published: December 2010

We investigated copper oxides for use as an active layer of p-channel field-effect thin-film transistors (TFTs). Cu2O thin films deposited at room temperature using rf magnetron sputtering were transformed to a CuO phase after an annealing treatment in air above 200 °C. The optical bandgaps of the Cu2O and CuO were 2.44 and 1.41 eV, respectively. The bottom gate structured TFTs fabricated using CuO active layers operated in a p-type enhancement mode with an on/off ratio of ∼104 and field-effect mobility of 0.4 cm2/V⋅s.
Titania nanostructure arrays from lithographically defined templates
Authors: Xia Deying , Jiang Ying-Bing , He Xiang , Brueck S. R. J.
Published: December 2010

We report the fabrication of TiO2 nanostructures with lithographically defined templates. Interferomeric-lithography was used to define soft templates (polymer posts), and a sol-gel solution was deposited on a patterned surface. In the final step, calcination was employed to form uniform low aspect-ratio crystalline nonclose-packed TiO2 nanotube arrays over a large area. Similarly, nanotree arrays and parallel nanotunnels were prepared as well. The position and morphology of TiO2 nanostructures were well controlled. These TiO2 nanostructures have a potential technological importance in clean energy, biosensor, and drug release.
Quantitative NO2 molecular tagging velocimetry at 500 kHz frame rate
Authors: Jiang Naibo , Nishihara Munetake , Lempert Walter R.
Published: December 2010

NO 2 molecular tagging velocimetry (MTV) is demonstrated at repetition rates as high as 500 kHz in a laboratory scale Mach 5 wind tunnel. A pulse burst laser and a home built optical parametric oscillator system were used to simultaneously generate the required 355 and 226 nm wavelengths for NO2 photodissociation (tagging) and NO planar laser induced fluorescence imaging (interrogation), respectively. NO2 MTV images were obtained both in front and behind the characteristic bow shock from a 5 mm diameter cylinder. From Gaussian curve fitting, an average free stream flow velocity of 719 m/s was obtained. Absolute statistical precision in velocity of ∼11.5 m/s was determined, corresponding to relative precision of 1.6%–5%, depending upon the region of the flow probed.
Spin-polarized charge carrier injection by tunneling from ferromagnetic contacts into organic semiconductors
Authors: Yunus M. , Ruden P. P. , Smith D. L.
Published: December 2010

Tunnel-injection of spin-polarized charge carriers from ferromagnetic contacts into organic semiconductors is modeled. Tunneling matrix elements and transition rates for the two spin types are calculated using a transfer Hamiltonian. The tunneling process occurs between extended states of the contact and model “molecular” orbitals. We explore the effects of the tunnel barrier height and of the ferromagnetic contact’s Fermi wave vectors on the level of spin injection. The barrier height and the majority and minority spin Fermi wave vectors of the contact have strong effects on the sign and magnitude of spin injection.
Response to “Comment on ‘Wall forces produced during ITER disruptions’ ” [Phys. Plasmas 17, 124703 (2010)]
Authors: Strauss H. R. , Paccagnella R. , Breslau J.
Published: December 2010

We offer a response to the claims of L. E. Zakharov.
Nonpropagating X-shaped acoustic waves in sonic crystals without defects
Authors: Kan Wei-Wei , Liang Bin , Zhu Xue-Feng , Tu Juan , Zou Xin-Ye , Cheng Jian-Chun
Published: December 2010

Three-dimensional localization of acoustic waves is investigated for a two-dimensional sonic crystal without defects. By studying the wave packet superposed by Bloch modes at the isofrequency surface, we predict the existence of nonpropagating X-shaped waves at either a local top point or a saddle point of a band, where diffractions in different directions cancel out. Different from traveling X waves in homogeneous media, acoustic energy can be localized stationarily within a small space region. Such a “soliton-like” feature has implication in diverse practical situations of focused ultrasound application where a focal region with high spatial stability is necessary.
High mobility two-dimensional electron gases in nitride heterostructures with high Al composition AlGaN alloy barriers
Authors: Li Guowang , Cao Yu , Xing Huili Grace , Jena Debdeep
Published: December 2010

We report high-electron mobility nitride heterostructures with >70% Al composition AlGaN alloy barriers grown by molecular beam epitaxy. Direct growth of such AlGaN layers on GaN resulted in hexagonal trenches and a low mobility polarization-induced charge. By applying growth interruption at the heterojunction, the surface morphology improved dramatically and the room temperature two-dimensional electron gas (2DEG) mobility increased by an order of magnitude, exceeding 1300 cm2/V s. The 2DEG density was tunable at 0.4–3.7×1013/cm2 by varying the total barrier thickness (t). Surface barrier heights of the heterostructures were extracted and exhibited dependence on t.
Ultrathin GeOxNy interlayer formed by in situ NH3 plasma pretreatment for passivation of germanium metal-oxide-semiconductor devices
Authors: Xie Qi , Musschoot Jan , Schaekers Marc , Caymax Matty , Delabie Annelies , Qu Xin-Ping , Jiang Yu-Long , Van den Berghe Sven , Liu Junhu , Detavernier Christophe
Published: December 2010

In situ NH3 plasma surface-nitridation treatments at 250 °C on both p- and n-type Ge(100) wafers were investigated. An ultrathin high quality GeOxNy interlayer was formed and exhibited dielectric breakdown for electric fields greater than 15 MV/cm. Well behaved capacitance-voltage characteristics were obtained for the complementary metal-oxide-semiconductor capacitors (CMOSCAPs) with HfO2(3 nm)/GeOxNy(1 nm) gate stacks. Gate leakage current density was below 5×10−7 A/cm2 at VFB±1 V for both MOSCAPs with an equivalent oxide thickness of 1.1 nm. Promising electrical properties of the CMOSCAPs indicate effective passivation of the Ge interface with GeOxNy interlayer formed by in situ NH3 plasma treatment.
Charge detection in phosphorus-doped silicon double quantum dots
Authors: Rossi A. , Ferrus T. , Podd G. J. , Williams D. A.
Published: December 2010

The ability to control and detect single electrons is paramount for the implementation of a scalable charge-based quantum computer and single-electron memory devices. Here, we report charge detection in degenerately phosphorus-doped silicon double quantum dots (DQD) that are electrically connected to an electron reservoir. The sensing device is a single-electron transistor patterned in close proximity to the DQD. We observe steplike behavior and shifts of the Coulomb blockade oscillations in the detector’s current as the reservoir’s potential is swept. By means of a classical capacitance model, we demonstrate that these features can be used to detect changes in the DQD charge occupancy.
Balloon experiment reveals a new way of finding ultrahigh-energy cosmic rays
Authors: Schwarzschild Bertram
Published: December 2010

The serendipitous discovery of strong radio pulses from those rarest of cosmic rays presents the prospect of monitoring large areas of ice or ocean in the quest to unveil their extragalactic origins.
Science diplomacy enlisted to span US divide with developing world
Authors: Kramer David
Published: December 2010

The Obama administration’s initiative for science and technology collaboration with developing nations is complemented by the efforts of scientific organizations.
How the brain integrates costs and benefits during decision making
Authors: Basten Ulrike , Biele Guido , Heekeren Hauke R. , Fiebach Christian J.
Published: December 2010

When we make decisions, the benefits of an option often need to be weighed against accompanying costs. Little is known, however, about the neural systems underlying such cost–benefit computations. Using functional magnetic resonance imaging and choice modeling, we show that decision making based on cost–benefit comparison can be explained as a stochastic accumulation of cost–benefit difference. Model-driven functional MRI shows that ventromedial and left dorsolateral prefrontal cortex compare costs and benefits by computing the difference between neural signatures of anticipated benefits and costs from the ventral striatum and amygdala, respectively. Moreover, changes in blood oxygen level dependent (BOLD) signal in the bilateral middle intraparietal sulcus reflect the accumulation of the difference signal from ventromedial prefrontal cortex. In sum, we show that a neurophysiological mechanism previously established for perceptual decision making, that is, the difference-based accumulation of evidence, is fundamental also in value-based decisions. The brain, thus, weighs costs against benefits by combining neural benefit and cost signals into a single, difference-based neural representation of net value, which is accumulated over time until the individual decides to accept or reject an option.
Nucleotide excision repair deficiency is intrinsic in sporadic stage I breast cancer
Authors: Latimer Jean J. , Johnson Jennifer M. , Kelly Crystal M. , Miles Tiffany D. , Beaudry-Rodgers Kelly A. , Lalanne Nancy A. , Vogel Victor G. , Kanbour-Shakir Amal , Kelley Joseph L. , Johnson Ronald R. , Grant Stephen G.
Published: December 2010

The molecular etiology of breast cancer has proven to be remarkably complex. Most individual oncogenes are disregulated in only approximately 30% of breast tumors, indicating that either very few molecular alterations are common to the majority of breast cancers, or that they have not yet been identified. In striking contrast, we now show that 19 of 19 stage I breast tumors tested with the functional unscheduled DNA synthesis assay exhibited a significant deficiency of DNA nucleotide excision repair (NER) capacity relative to normal epithelial tissue from disease-free controls (
n
= 23). Loss of DNA repair capacity, including the complex, damage-comprehensive NER pathway, results in genomic instability, a hallmark of carcinogenesis. By microarray analysis, mRNA expression levels for 20 canonical NER genes were reduced in representative tumor samples versus normal. Significant reductions were observed in 19 of these genes analyzed by the more sensitive method of RNase protection. These results were confirmed at the protein level for five NER gene products. Taken together, these data suggest that NER deficiency may play an important role in the etiology of sporadic breast cancer, and that early-stage breast cancer may be intrinsically susceptible to genotoxic chemotherapeutic agents, such as
cis
-platinum, whose damage is remediated by NER. In addition, reduced NER capacity, or reduced expression of NER genes, could provide a basis for the development of biomarkers for the identification of tumorigenic breast epithelium.
Trehalose-recycling ABC transporter LpqY-SugA-SugB-SugC is essential for virulence of
Mycobacterium tuberculosis
Authors: Kalscheuer Rainer , Weinrick Brian , Veeraraghavan Usha , Besra Gurdyal S. , Jacobs William R.
Published: December 2010

Mycobacterium tuberculosis
(
Mtb
) is an exclusively human pathogen that proliferates within phagosomes of host phagocytes. Host lipids are believed to provide the major carbon and energy sources for
Mtb
, with only limited availability of carbohydrates. There is an apparent paradox because five putative carbohydrate uptake permeases are present in
Mtb
, but there are essentially no host carbohydrates inside phagosomes. Nevertheless, carbohydrate transporters have been implicated in
Mtb
pathogenesis, suggesting that acquisition of host sugars is important during some stages of infection. Here we show, however, that the LpqY-SugA-SugB-SugC ATP-binding cassette transporter is highly specific for uptake of the disaccharide trehalose, a sugar not present in mammals, thus refuting a role in nutrient acquisition from the host. Trehalose release is known to occur as a byproduct of the biosynthesis of the mycolic acid cell envelope by
Mtb
’s antigen 85 complex. The antigen 85 complex constitutes a group of extracellular mycolyl transferases, which transfer the lipid moiety of the glycolipid trehalose monomycolate (TMM) to arabinogalactan or another molecule of TMM, yielding trehalose dimycolate. These reactions also lead to the concomitant extracellular release of the trehalose moiety of TMM. We found that the LpqY-SugA-SugB-SugC ATP-binding cassette transporter is a recycling system mediating the retrograde transport of released trehalose. Perturbations in trehalose recycling strongly impaired virulence of
Mtb
. This study reveals an unexpected accessory component involved in the formation of the mycolic acid cell envelope in mycobacteria and provides a previously unknown role for sugar transporters in bacterial pathogenesis.
MicroRNA-125b expands hematopoietic stem cells and enriches for the lymphoid-balanced and lymphoid-biased subsets
Authors: Ooi A. G. Lisa , Sahoo Debashis , Adorno Maddalena , Wang Yulei , Weissman Irving L. , Park Christopher Y.
Published: December 2010

MicroRNAs profoundly impact hematopoietic cells by regulating progenitor cell-fate decisions, as well as mature immune effector function. However to date, microRNAs that regulate hematopoietic stem cell (HSC) function have been less well characterized. Here we show that microRNA-125b (miR-125b) is highly expressed in HSCs and its expression decreases in committed progenitors. Overexpression of miR-125b in mouse HSC enhances their function, demonstrated through serial transplantation of highly purified HSC, and enriches for the previously described Slamf1
lo
CD34
−
lymphoid-balanced and the Slamf1
neg
CD34
−
lymphoid-biased cell subsets within the multipotent HSC (CD34-KLS) fraction. Mature peripheral blood cells derived from the miR-125b–overexpressing HSC are skewed toward the lymphoid lineage. Consistent with this observation, miR-125b overexpression significantly increases the number of early B-progenitor cells within the spleen and induces the expansion and enrichment of the lymphoid-balanced and lymphoid-biased HSC subset via an antiapoptotic mechanism, reducing the mRNA expression levels of two proapoptotic targets, Bmf and KLF13. The antiapoptotic effect of miR-125b is more pronounced in the lymphoid-biased HSC subset because of their intrinsic higher baseline levels of apoptosis. These effects of miR-125b are associated with the development of lymphoproliferative disease, marked by expansion of CD8
+
T lymphocytes. Taken together, these data reveal that miR-125b regulates HSC survival and can promote lymphoid-fate decisions at the level of the HSC by preferentially expanding lymphoid-balanced and lymphoid-biased HSC.
As
4
S
4
targets RING-type E3 ligase c-CBL to induce degradation of BCR-ABL in chronic myelogenous leukemia
Authors: Mao Jian-Hua , Sun Xiao-Yan , Liu Jian-Xiang , Zhang Qun-Ye , Liu Ping , Huang Qiu-Hua , Li Keqin Kathy , Chen Quan , Chen Zhu , Chen Sai-Juan
Published: December 2010

Arsenic, a curative agent for acute promyelocytic leukemia, induces cell apoptosis and degradation of BCR-ABL in chronic myelogenous leukemia (CML). We demonstrated that ubiquitination and degradation of BCR-ABL was mediated by c-CBL, a RING-type E3 ligase that was also shown to be involved in ubiquitination for many other receptor/protein tyrosine kinases. Our data showed that c-CBL protein was considerably up-regulated by arsenic sulfide (As
4
S
4
). Interestingly, arsenic directly bound the RING finger domain of c-CBL to inhibit its self-ubiquitination/degradation without interfering with the enhancement of ubiquitination and subsequent proteolysis of its substrate BCR-ABL. Degradation of BCR-ABL due to c-CBL induction as a result of arsenic treatment was also observed in vivo in CML mice. These findings provide insight into the molecular mechanisms of arsenic and further support its therapeutic applications in CML in combination with tyrosine kinase inhibitors and potentially also in other malignancies involving aberrant receptor/protein tyrosine kinase signaling.
Influence of socially involved hand-raising on life history and stress responses in greylag geese
Authors: Hemetsberger Josef , Scheiber Isabella B.R. , Weiß Brigitte M. , Frigerio Didone , Kotrschal Kurt
Published: November 2010

Animals are hand-raised in a variety of contexts, including experimental research. This has been criticized frequently as producing animals with species-untypical behaviour. Here we compare life histories of 330 hand-raised and 631 gooseraised Greylag geese from a free-flying flock to determine whether hand-raising affected life history, reproductive variables and behaviour. We found little differences in life histories (e.g. male age, age at pair bond) or reproductive variables (e.g. number of eggs, egg weight, number of young hatched and fledged) of hand-raised and goose-raised geese. However, hand-raised females had lower life expectancies than goose-raised ones, mainly due to predation during breeding. Hand-raised geese were stressed significantly less during social, handling and predator stress, were attacked less by conspecifics and were less vigilant than goose-raised geese. We conclude that hand-raising resulted in geese with species-typical life histories but reduced stress responses. This makes hand-raised geese cooperative partners for research, but also more vulnerable when exposed to predators. Keywords: hand-raising; greylag goose; Anser anser; life-history; reproductive success; stress
Caregiver–chimpanzee interactions with species-specific behaviors
Authors: Jensvold Mary Lee A. , Buckner Jacquelyn C. , Stadtner Gina B.
Published: November 2010

The relationships between captive primates and their caregivers are critical ones and can affect animal welfare. This study tested the effect of caregivers using chimpanzee behaviors or not, in daily interactions with captive chimpanzees. In the Chimpanzee Behavior (CB) condition the caregiver presented chimpanzee behaviors. In the Human Behavior (HB) condition the caregiver avoided using chimpanzee behaviors. The chimpanzees had individual patterns of response and had significant differences in their responses to each condition. These data are compared to a similar study conducted at The Zoo Northwest Florida (ZNWF). Both groups of chimpanzees were sensitive and responsive to the differences in conditions. These data suggest ways to improve animal welfare. Keywords: chimpanzee behavior; animal welfare; species-specific behavior; husbandry
Relational factors affecting dog social attraction to human partners
Authors: Wedl Manuela , Schöberl Iris , Bauer Barbara , Day Jon , Kotrschal Kurt
Published: November 2010

We previously showed (Kotrschal et al., 2009) that owner personality and human–dog relationship predicted the performance of a human–dog dyad in a practical task. Based on the same data set we presently investigate the effects of individual and social factors on the social attraction of dogs to their owners. Twenty-two male and female owners and their intact male dogs were observed during a “picture viewing” test, where we diverted the owner’s attention away from their dog whilst it was permitted to move freely around the room. Owner personality axis “neuroticism” and dog personality axis “vocal and aggressive” were, respectively, positively and negatively related to the time the dog stayed in proximity to the owner. Quality of relationship and attachment also had significant effects on this proximity. We conclude that personality and the nature of the human–dog relationship may all influence dogs’ social attraction to their owners. Keywords: companion animals; dog–human attachment; dyadic relationships; human-animal interactions; human–dog attachment; human–dog relationship; human–dog social interactions; personality; pets
Réflexions Sur la Théorie de L'article de Gustave Guillaume
Authors: Karolak Stanislaw
Published: November 2010

This paper is concerned with the analysis of the theory of the French article presented in the classical work by Guillaume "Le problème de l'article et sa solution dans la langue française". The paper emphasizes Guillaume's search for the semantic nature of the relationships determining the distribution of articles. The paper supports Guillaume, who seems to claim, contrary to what is commonly believed, that the function of the articles is non inherent in them, but that it is determined by the semantic properties of the nouns which select them. Treating this claim as the starting point, the paper focuses on the analysis of various senses of noun phrases, carried out in terms of the functional calculus. The applied method invalidates the extensional theory of the noun accepted by Guillaume, as well as a number of generalisations made by him.
The paper shows logical and semantic conditions of some rules governing the use of the article. They differ from those proposed by Guillaume in that they seem to reach a deeper level of linguistic mechanisms. On the other hand, the emphasis is laid on Guillaume's subtle analysis and detailed observations, which stand in a sharp contrast to his rather vague generalizations.
Le Complément D'agent Introduit Par la Préposition de
Authors: Schapira Charlotte
Published: November 2010

The purpose of this study is to draw attention on a syntactic function somewhat neglected till now in literature: the agent introduced by de in French.
A reconsideration of the data led us to a new classification of the verbs admitting such an agent. Some other points (such as the status of this complement with the verbs accepting both direct and prepositional objects, or the affinity of the preposition with undeterminated objects) have been discussed, leading to conclusions different from those generally accepted in grammars and textbooks.
Le Problème Des Forclusifs Romans
Authors: Bremen Klaus von
Published: November 2010

RESUME
L'analyse des forclusifs comme ou bien des quantifieurs, ou bien des anaphores n'est pas tenable. Plutôt, ils sont à analyser comme des TPN d'un genre spécial, ayant une lecture très générale et abstraite, mais non-émotive, et différente de celle des TPN ordinaires. Ils sont associés à une négation sous-jacente, négation qui s'efface en structure de surface dans certains contextes, effacement sujet à des contraintes variant de langue en langue.
Les TPN comme âme qui vive, palabra, de la vie, en la vida ont un caractère intermédiaire. Ce sont fondamentalement des TPN "ordinaires", mais qui par leur lecture très générale s'apparentent aux forclusifs, avec lesquels ils partagent certains traits syntaxiques, comme l'omission de pas et de ni. Ces particules sont des encodages, en structure de surface, de la dépendance des TPN ordinaires de la négation.
SUMMARY
Terms like French (ne) personne, Italian (non) nessuno have been dealt with as either polarity items, anaphors or quantifiers. The latter two analyses are based on either faulty, doubtful or insufficient data.
On my analysis, they are indefinite pronouns of a very general reading, associated with an underlying negation, which is deleted under conditions varying as between both languages and contexts. As such, they occur both in simple negated sentences, corresponding to English nobody, etc., and in polarity contexts, corresponding to anybody, etc. They are not restricted to emotive contexts.
Terms like (pas) un chat occur only in emotive contexts, and result in a reading, where the polarity item forms unity with the negation.
Terms like âme qui vive occupy an intermediate position behaving syntactically more like (pas) un chat, etc., but carrying the very general reading of (ne) personne, etc., and, like the latter, deleting the negation in certain contexts.
Propriétés Sémantiques Des Verbes Promoteurs De La Négation En Français
Authors: Iordanskaja Lidija
Published: November 2010

This paper describes some semantic properties of verbs which admit Neg-raising proceeding from their semantic representation (= semantic decompositions). One new concept relevant to Neg-raising verbs is proposed: negation semantic scope (NSS; the scope of negation in the semantic representation of a verb). Usually, the NSS of a V extends to the whole assertive part of its semantic representation (standard NSS). However, for some verbs (French approuver, conseiller, permettre, etc.) the NSS does not include the central predicate of the assertive part of their semantic representation (special NSS). The special NSS is manifested by various pragmatic, semantic, and syntactic properties of the construction "negative particle + V with special NSS". The special NSS must be lexically specified for the verb in the dictionary.
Le Developpement Des Pronoms Relatifs Qui Et Que Dans L'Acquisition Du Français
Authors: Pagani Caterina
Published: November 2010

It results from the analysis of our data that IL's are actually systematic even if they present a certain variability, due to the fact that they are systems under continuous evolution. Our learners' ILs are characterized by their own rules, rules which do not derive from the interference of the first language but rather from some general and abstract principles which can account for language learning in the most different situations. In particular from our data it results that, at least in earlier stages, semantic features play a more preponderant role than syntactic functions. Moreover IL's seem to be submitted to universal constraints similar to those proposed for natural languages (i.e. language universals such as the "Accessibility Hierarchy" by Keenan and Comrie).
Against Complete Precedence and Temporal Overlap in the Semantics of Tense and Aspect
Authors: Vikner Carl
Published: November 2010

Carl Vikner: "Against complete precedence and temporal overlap in the semantics of tense and aspect".
The paper criticizes the use of the relations complete precedence and temporal overlap, in some recent and influential works of Hans Kamp, to represent the temporal relations between events and situations as expressed by French Passé Simple and Imparfait. These relations are replaced by the relation of (simple) precedence defined over beginnings of events and by the relation of inclusion holding between the beginning of an event and a situation in its entirety.
The Indefinite Article and the Restrictive Relative Clause in Italian
Authors: Vietri Simonetta
Published: November 2010

Cet article traite des phrases relatives restrictives attachées a un syn-tagme nominal avec déterminant indéfini en italien. Dans une première partie l'on montre que les valeurs "spécifique" et "non-spécifique" de l'article UN dépendent du temps-mode de la relative et ensuite des valeurs tempo-aspectuels du verbe de la phrase principale. L'analyse détaillée des entrées lexicales met en lumière l'existence d'au moins deux classes de verbes qui déterminent, en combinaison avec la relative et le temps-mode, des interprétations différentes de l'article UN.
Actes De Langage, Semi-Actes Et Typologie Des Connecteurs Pragmatiques
Authors: Rubattel Christian
Published: November 2010

This article deals with the syntactic properties of pragmatic connectives and with the relationship between their distributional and argumentative properties. Recent discourse models based on speech act theory assume that pragmatic connectives link sentences (or larger units). However, certain phrasal categories too can function as discourse units, and the set of pragmatic connectives therefore includes not only markers linking sentences provided with an illocutionary force (speech acts), but also phrases lacking an asserted illocutionary force (semi-speech acts). Moreover, many connectives either belong to the two subsets or are in complementary distribution, depending on the syntactic environment.
Except for coordination, all these connectives are members of only two grammatical categories: Universal subordinators (including complementizers, subordinating conjunctions and prepositions), and modifying adverbs.
Coordinate conjunctions are briefly reconsidered, and some arguments are given for restricting this class to et, ou and ni, both on pragmatic and on syntactic grounds.
Analysis by Fusion
Authors: Salkoff Morris
Published: November 2010

Sentences of the type Max elbowed his way through the crowd have not been studied in detail hitherto. The systematic investigation undertaken here shows that the verbs appearing in them have a large lexical extension. These sentences are also productive, so that an unlimited number of new verbs of the paradigm are constantly being created; the verbs constitute an open class. Three new results have been obtained. The first shows how certain apparently inexplicable uses of it (as in beat it!) can be related to a pro-nominalization observed in the paradigm. The second shows how nouns like cannonball, steamroller, skyrocket, etc., can become verbs. The third result is a verification, by a systematic investigation of the English lexicon, of the common semantic intuition that these sentences can be paraphrased by others like Max made his way through the crowd by using his elbows.
L'interprétation Événementielle des Phrases en Il Y A
Authors: Giry-Schneider Jacqueline
Published: November 2010

This paper presents an illustration of the claim that it is possible to treat a semantic problem with the use of syntactic data only, i.e. without appealing to extralinguistic considerations. The example in question is concerned with French clauses constructed around Il y a, for example
Il y a un tank dans le jardin
(There is a tank in the garden)
The event interpretation of such a clause can be explained by the pseudo-sentential clause construction Il y a que S, which is formally related to such clauses.
Un Mot, des Fonctions, des Contextes
Authors: Moreau Marie-Louise
Published: November 2010

We presented six words to subjects, who were asked to produce a sentence for each of these words. Results show that each word occupies one or two dominating syntactic positions. This can be explained by semantic stereotypy and by syntactic stereotypy. This last notion refers to idiomatisms, "couplons", preformed sequences and semantico-syntactic structures.
The whole study leads to the conclusion that subjects do not memorize isolated words but rather that they memorize words together with the semantic and syntactic contexts in which they previously met them.