bluuebunny/crossref_metadata_2025 huggingface dataset:
Post-transcriptional and post-translational regulation of Bcl2
Authors: Willimott Shaun , Wagner Simon D.
Published: December 2010

Bcl2 is an important pro-survival protein that has an essential function in normal immunity and whose constitutive expression leads to the development of lymphomas. Although transcriptional control of Bcl2 has been reported, increasing evidence suggests an important component of Bcl2 regulation is post-transcriptional. Phosphorylation of Bcl2 has been shown to enhance activity to allow response to extracellular growth-factor-mediated signals. Bcl2 mRNA contains regulatory elements in both its 5′- and 3′-UTRs (untranslated regions). An IRES (internal ribosome entry sequence) in the 5′-UTR permits continued translation in the presence of cellular stresses that reduce cap-dependent translation. The 3′-UTR of Bcl2 mRNA is 5.2 kb in length and contains multiple predicted miRNA (microRNA) and RNA-BP (RNA-binding protein)-binding sites. miR-15a and miR-16-1 have been found to inhibit Bcl2 expression in B-cells, whereas the RNA-BP nucleolin has been shown to increase Bcl2 expression by binding to the 3′-UTR and enhancing mRNA stability. Both decreased expression of miR-15a and miR-16-1 and increased nucleolin have been shown to be associated with increased Bcl2 expression and resistance to apoptosis in the common human disease, chronic lymphocytic leukaemia. miRNA-based therapeutic approaches to treat cancer are emerging. Bcl2 is highly regulated by miRNAs and is therefore an excellent candidate for such approaches.
RNA-binding E3 ubiquitin ligases: novel players in nucleic acid regulation
Authors: Cano Florencia , Miranda-Saavedra Diego , Lehner Paul J.
Published: December 2010

Non-coding RNAs and their interaction with RNA-binding proteins regulate mRNA levels in key cellular processes. This has intensified interest in post-transcriptional regulation. Recent studies on the turnover of AU-rich cytokine mRNAs have linked mRNA metabolism with ubiquitination. Ubiquitin is well recognized for its role in protein regulation/degradation. In the present paper, we describe a new group of RNA-binding E3 ubiquitin ligases which are predicted to bind and regulate RNA stability. Although much effort has been focused on understanding the role of these proteins as key regulators of mRNA turnover, the requirement for E3 ligase activity in mRNA decay remains unclear. It is remarkable that the ubiquitin system is involved, either directly or indirectly, in both the degradation of nucleic acids as well as proteins. These new RNA-binding E3 ligases are potential candidates which link two important cellular regulatory pathways: the regulation of both protein and mRNA stability.
Chromosomal and cytoplasmic context determines predisposition to maternal age-related aneuploidy: brief overview and update on MCAK in mammalian oocytes
Authors: Eichenlaub-Ritter Ursula , Staubach Nora , Trapphoff Tom
Published: December 2010

It has been known for more than half a century that the risk of conceiving a child with trisomy increases with advanced maternal age. However, the origin of the high susceptibility to nondisjunction of whole chromosomes and precocious separation of sister chromatids, leading to aneuploidy in aged oocytes and embryos derived from them, cannot be traced back to a single disturbance and mechanism. Instead, analysis of recombination patterns of meiotic chromosomes of spread oocytes from embryonal ovary, and of origins and exchange patterns of extra chromosomes in trisomies, as well as morphological and molecular studies of oocytes and somatic cells from young and aged females, show chromosome-specific risk patterns and cellular aberrations related to the chronological age of the female. In addition, analysis of the function of meiotic- and cell-cycle-regulating genes in oogenesis, and the study of the spindle and chromosomal status of maturing oocytes, suggest that several events contribute synergistically to errors in chromosome segregation in aged oocytes in a chromosome-specific fashion. For instance, loss of cohesion may differentially predispose chromosomes with distal or pericentromeric chiasmata to nondisjunction. Studies on expression in young and aged oocytes from human or model organisms, like the mouse, indicate that the presence and functionality/activity of gene products involved in cell-cycle regulation, spindle formation and organelle integrity may be altered in aged oocytes, thus contributing to a high risk of error in chromosome segregation in meiosis I and II. Genes that are often altered in aged mouse oocytes include MCAK (mitotic-centromere-associated protein), a microtubule depolymerase, and AURKB (Aurora kinase B), a protein of the chromosomal passenger complex that has many targets and can also phosphorylate and regulate MCAK localization and activity. Therefore we explored the role of MCAK in maturing mouse oocytes by immunofluorescence, overexpression of a MCAK–EGFP (enhanced green fluorescent protein) fusion protein, knockdown of MCAK by RNAi (RNA interference) and inhibition of AURKB. The observations suggest that MCAK is involved in spindle regulation, chromosome congression and cell-cycle control, and that reductions in mRNA and protein in a context of permissive SAC (spindle assembly checkpoint) predispose to aneuploidy. Failure to recruit MCAK to centromeres and low expression patterns, as well as disturbances in regulation of enzyme localization and activity, e.g. due to alterations in activity of AURKB, may therefore contribute to maternal age-related rises in aneuploidy in mammalian oocytes.
Different outcomes of telomere-dependent anaphase bridges
Authors: Tusell Laura , Pampalona Judit , Soler David , Frías Cristina , Genescà Anna
Published: December 2010

Chromosomal instability occurs early in the development of cancer and may represent an important step in promoting the multiple genetic changes required for the initiation and/or progression of the disease. Telomere erosion is one of the factors that contribute to chromosome instability through end-to-end chromosome fusions entering BFB (breakage–fusion–bridge) cycles. Uncapped chromosomes with short dysfunctional telomeres represent an initiating substrate for both pre- and post-replicative joining, which leads to unstable chromosome rearrangements prone to bridge at mitotic anaphase. Resolution of chromatin bridge intermediates is likely to contribute greatly to the generation of segmental chromosome amplification events, unbalanced chromosome rearrangements and whole chromosome aneuploidy. Accordingly, telomere-driven instability generates highly unstable genomes that could promote cell immortalization and the acquisition of a tumour phenotype.
Loss of the tumour-suppressor genes CHK2 and BRCA1 results in chromosomal instability
Authors: Stolz Ailine , Ertych Norman , Bastians Holger
Published: December 2010

CHK2 (checkpoint kinase 2) and BRCA1 (breast cancer early-onset 1) are tumour-suppressor genes that have been implicated previously in the DNA damage response. Recently, we have identified CHK2 and BRCA1 as genes required for the maintenance of chromosomal stability and have shown that a Chk2-mediated phosphorylation of Brca1 is required for the proper and timely assembly of mitotic spindles. Loss of CHK2, BRCA1 or inhibition of its Chk2-mediated phosphorylation inevitably results in the transient formation of abnormal spindles that facilitate the establishment of faulty microtubule–kinetochore attachments associated with the generation of lagging chromosomes. Importantly, both CHK2 and BRCA1 are lost at very high frequency in aneuploid lung adenocarcinomas that are typically induced in knockout mice exhibiting chromosomal instability. Thus these results suggest novel roles for Chk2 and Brca1 in mitosis that might contribute to their tumour-suppressor functions.
piggyBac‐mediated transposition in Drosophila melanogaster: an evaluation of the use of constitutive promoters to control transposase gene expression
Authors: Li X. , Heinrich J. C. , Scott M. J.
Published: November 2010

Transgenic non‐Drosophilid insects have been made using insect transposable elements that have a broad host range such as the piggyBac element. However, the success rate is often low. Previous piggyBac helper plasmids have used either the piggyBac or the hsp70 promoter from Drosophila melanogaster to control expression of the transposase gene. Here we show that plasmids with the piggyBac transposase gene regulated by constitutive promoters can be effective ‘helpers’ for mediating transposition in D. melanogaster. We also present preliminary evidence on the use of an RNA helper that encodes the transposase. Our results suggest that for germ‐line transformation of non‐Drosophilid insects it may be advantageous to isolate a constitutive promoter from the species of interest to control transposase expression.
Substance P stimulates sphincter of Oddi motility and inhibits trans‐sphincteric flow in the Australian brush‐tailed possum
Authors: Cox M. R. , Padbury R. T. A. , Harvey J. R. , Baker R. A. , Toouli J. , Saccone G. T. P.
Published: November 2010

Substance P containing nerves are widely distributed throughout the gastrointestinal tract. The aims of this study were to determine the distribution of substance P containing nerves in the extrahepatic biliary tree of the Australian brush‐tailed possum and to characterize the effect of exogenous substance P on the sphincter of Oddi (SO) motility and trans‐sphincteric flow in vivo. Immunohistochemical staining of fixed specimens (n = 8) found moderate numbers of substance P containing nerve cell bodies and fibres throughout the neural plexuses of the SO, in particular in the serosal and intraluminal nerve trunks of the SO and gallbladder. Synthetic porcine substance P (1–2000 ng kg−1), administered by close intra‐arterial injection (i.a. n = 7), produced a dose‐dependent elevation in basal pressure [P < 0.01] and an associated dose‐dependent reduction in trans‐sphincteric flow [P < 0.0001]. Substance P had no significant dose‐dependent effect on SO phasic contraction amplitude or frequency. Tetrodotoxin (9 μg kg−1, i.a.) did not inhibit the effect of substance P on SO motility and trans‐sphincteric flow (n = 5). In conclusion, substance P containing nerves are found throughout the possum extrahepatic biliary tree. Exogenous substance P stimulates SO motility and reduces trans‐sphincteric flow in vivo by acting directly on the sphincter smooth muscle.
A Retrospective Review of Malignant Minor Salivary Gland Tumors and a Proposed Protocol for Future Care
Authors: Papadogeorgakis Nickolaos , Parara Eleni , Petsinis Vasilis , Pappa Eleni , Nikolaidis Anastasios , Alexandridis Konstantinos
Published: December 2010

Malignant tumors affecting minor salivary glands present a wide range of histopathologic types. The present study sought to design a protocol for management of patients with malignancy of minor salivary glands. The data of 22 patients with malignant tumors of the minor salivary glands, surgically treated at our department in the past 10 years, were accumulated and studied. All patients underwent a diagnostic workup prior to surgery. The most useful examinations were magnetic resonance imaging of the head and neck and computerized tomography of the thorax. Wide local excision was sufficient for the majority of patients. Adjuvant treatment is indicated for high-grade, tumor-positive lymph nodes and residual disease. Malignant tumors of minor salivary glands are very rare. Therefore, design of management protocols is challenging. Management of the neck is necessary in evidence of metastasis and in high-grade and advanced-stage disease. Adjuvant treatment should be included in the treatment protocol in certain indications. Most importantly, long-term follow up is very important for all patients with malignant minor salivary tumors.
Time and space resolved interferometry for laser-generated fast electron measurements
Authors: Antici P. , Chen S. N. , Gremillet L. , Grismayer T. , Mora P. , Audebert P. , Fuchs J.
Published: December 2010

A technique developed to measure in time and space the dynamics of the electron populations resulting from the irradiation of thin solids by ultraintense lasers is presented. It is a phase reflectometry technique that uses an optical probe beam reflecting off the target rear surface. The phase of the probe beam is sensitive to both laser-produced fast electrons of low-density streaming into vacuum and warm solid density electrons that are heated by the fast electrons. A time and space resolved interferometer allows to recover the phase of the probe beam sampling the target. The entire diagnostic is computationally modeled by calculating the probe beam phase when propagating through plasma density profiles originating from numerical calculations of plasma expansion. Matching the modeling to the experimental measurements allows retrieving the initial electron density and temperature of both populations locally at the target surface with very high temporal and spatial resolution (∼4 ps,6 μm). Limitations and approximations of the diagnostic are discussed and analyzed.
Constitutive modeling of intrinsic and oxygen-contaminated silicon monocrystals in easy glide
Authors: Cochard J. , Yonenaga I. , Gouttebroze S. , M’Hamdi M. , Zhang Z. L.
Published: December 2010

We generalize in this work the constitutive model for silicon crystals of Alexander and Haasen. Strain-rate and temperature dependency of the mechanical behavior of intrinsic crystals are correctly accounted for into stage I of hardening. We show that the steady-state of deformation in stage I is very well reproduced in a wide range of temperature and strain rate. The case of extrinsic crystals containing high levels of dissolved oxygen is examined. The introduction of an effective density of mobile dislocations dependent on the unlocking stress created by oxygen atoms gathered at the dislocation cores is combined to an alteration of the dislocation multiplication rate, due to pinning of the dislocation line by oxygen atoms. This increases the upper yield stress with the bulk oxygen concentration in agreement with experimental observations. The fraction of effectively mobile dislocations is found to decay exponentially with the unlocking stress. Finally, the influence of oxygen migration back onto the dislocations from the bulk on the stress distribution in silicon bars is investigated.
A coupled map lattice model for rheological chaos in sheared nematic liquid crystals
Authors: Kamil S. M. , Menon Gautam I. , Sinha Sudeshna
Published: November 2010

A variety of complex fluids under shear exhibit complex spatiotemporal behavior, including what is now termed rheological chaos, at moderate values of the shear rate. Such chaos associated with rheological response occurs in regimes where the Reynolds number is very small. It must thus arise as a consequence of the coupling of the flow to internal structural variables describing the local state of the fluid. We propose a coupled map lattice model for such complex spatiotemporal behavior in a passively sheared nematic liquid crystal using local maps constructed so as to accurately describe the spatially homogeneous case. Such local maps are coupled diffusively to nearest and next-nearest neighbors to mimic the effects of spatial gradients in the underlying equations of motion. We investigate the dynamical steady states obtained as parameters in the map and the strength of the spatial coupling are varied, studying local temporal properties at a single site as well as spatiotemporal features of the extended system. Our methods reproduce the full range of spatiotemporal behavior seen in earlier one-dimensional studies based on partial differential equations. We report results for both the one- and two-dimensional cases, showing that spatial coupling favors uniform or periodically time-varying states, as intuitively expected. We demonstrate and characterize regimes of spatiotemporal intermittency out of which chaos develops. Our work indicates that similar simplified lattice models of the dynamics of complex fluids under shear should provide useful ways to access and quantify spatiotemporal complexity in such problems, in addition to representing a fast and numerically tractable alternative to continuum representations.
Theory of macroscopic fluctuations in systems of particles, interacting with hydrodynamic and gaslike media
Authors: Nikolayenko S. O. , Slyusarenko Yu. V.
Published: November 2010

Our work offers a stochastic approach for description of long wave fluctuations in systems of particles interacting with hydrodynamic media. The approach is based on the averaging of nonlinear dynamic equations over random initial conditions for these equations. Random character of the initial conditions for motion equations causes the development of long wave fluctuations of description parameters in the system. Within the framework of our approach we derived evolution equations of long wale fluctuations in the system for both fluctuation-kinetic and fluctuation-hydrodynamic stages of evolution. We also found the class of description parameter transformations which does not change the dynamic equation structure. Dynamics of pair correlations has been studied. The “long hydrodynamic tails” theory for system of particles interacting with the hydrodynamic medium has been built. The system considered can be a model of neutron transport in hydrodynamic media without their multiplication and capture. The possibility of usage of our results for experimental evidence of long hydrodynamic tails in neutron scattering experiments is discussed.
Photofragment angular momentum distributions in the molecular frame. III. Coherent effects in the photodissociation of polyatomic molecules with circularly polarized light
Authors: Rakitzis T. Peter
Published: November 2010

We extend the $a_q^k (s)$aqk(s) polarization parameter model [T. P. Rakitzis and A. J. Alexander, J. Chem. Phys. 132, 224310 (2010)] to describe the components of the product angular momentum polarization that arise from the one-photon photodissociation of asymmetric top molecules with circularly polarized photolysis light, and provide a general equation for fitting experimental signals. We show that the only polarization parameters that depend on the helicity of the circularly polarized photolysis light are the $A_0^k$A0k and ${\rm Re}[A_1^k]$Re[A1k] (with odd k) and the ${\rm Im}[A_1^k]$Im[A1k] (with even k); in addition, for the unique recoil destination (URD) approximation [for which the photofragment recoil v arises from a unique parent molecule geometry], we show that these parameters arise only as a result the interference between at least two dissociative electronic states. Furthermore, we show that in the breakdown of the URD approximation (for which the photofragment recoil v arises from a distribution of parent molecule geometries), these parameters can also arise for dissociation via a single dissociative electronic state. In both cases, the $A_0^k$A0k and ${\rm Re}[A_1^k]$Re[A1k] parameters (with odd k) are proportional to cosΔϕ, and the ${\rm Im}[A_1^k]$Im[A1k] parameters (with even k) are proportional to sinΔϕ, where Δϕ is the phase shift (or average phase shift) between the interfering paths so that Δϕ can be determined directly from the $A_q^k$Aqk, or from ratios of these $A_q^k$Aqk parameters. Therefore, the determination of these $A_q^k$Aqk parameters with circularly polarized photolysis light allows the unambiguous measurement of coherent effects in polyatomic–molecule photodissociation.
Water-gas shift reaction on oxide/Cu(111): Rational catalyst screening from density functional theory
Authors: Liu Ping
Published: December 2010

Developing improved catalysts based on a fundamental understanding of reaction mechanism has become one of the grand challenges in catalysis. A theoretical understanding and screening the metal-oxide composite catalysts for the water-gas shift (WGS) reaction is presented here. Density functional theory was employed to identify the key step for the WGS reaction on the Au, Cu–oxide catalysts, where the calculated reaction energy for water dissociation correlates well with the experimental measured WGS activity. Accordingly, the calculated reaction energy for water dissociation was used as the scaling descriptor to screen the inverse model catalysts, oxide/Cu(111), for the better WGS activity. Our calculations predict that the WGS activity increases in a sequence: Cu(111), ZnO/Cu(111) < TiO2/Cu(111), ZrO2/Cu(111) < MoO3/Cu(111). Our results imply that the high performances of Au, Cu–oxide nanocatalysts in the WGS reaction rely heavily on the direct participation of both oxide and metal sites. The degree that the oxide is reduced by Cu plays an important role in determining the WGS activity of oxide/Cu catalysts. The reducible oxide can be transformed from the fully oxidized form to the reduced form due to the interaction with Cu and, therefore, the transfer of electron density from Cu, which helps in releasing the bottleneck water dissociation and, therefore, facilitating the WGS reaction on copper.
Quantum integrals and anhomomorphic logics
Authors: Gudder Stan
Published: November 2010

The basic arena for a probabilistic structure is a set \documentclass[12pt]{minimal}\begin{document}${\mathcal A}$\end{document}A of events. Corresponding to \documentclass[12pt]{minimal}\begin{document}${\mathcal A}$\end{document}A is a dual structure \documentclass[12pt]{minimal}\begin{document}${\mathcal A}^*$\end{document}A* of coevents. We call \documentclass[12pt]{minimal}\begin{document}${\mathcal A}^*$\end{document}A* an anhomomorphic logic and the coevents are given by “truth functions” from \documentclass[12pt]{minimal}\begin{document}${\mathcal A}$\end{document}A to the two-element Boolean algebra \documentclass[12pt]{minimal}\begin{document}${\mathbb Z}_2=\left\lbrace 0,1\right\rbrace$\end{document}Z2=0,1. One of the main goals of a physical theory is to describe physical reality and a coevent \documentclass[12pt]{minimal}\begin{document}$\phi:{\mathcal A}\rightarrow {\mathbb Z}_2$\end{document}φ:A→Z2 provides such a description in the sense that an event \documentclass[12pt]{minimal}\begin{document}$A\in {\mathcal A}$\end{document}A∈A “actually occurs” if and only if ϕ(A) = 1. The quantum integral over an event A with respect to a coevent ϕ is defined and its properties are treated. Integrals with respect to various coevents are computed. Quantum systems are frequently described by a quantum measure μ which gives the propensity μ(A) that an event A occurs. For \documentclass[12pt]{minimal}\begin{document}$\phi \in {\mathcal A}^*$\end{document}φ∈A*, if ϕ(A) = 0 whenever μ(A) = 0 we say that ϕ is preclusive. Preclusivity is a reality filter because it eliminates coevents that do not describe a possible reality for the system. A quantum measure that can be represented as a quantum integral with respect to a coevent ϕ is said to 1-generate ϕ. This gives a stronger reality filter than preclusivity. What we believe to be a more general filter is defined in terms of a double quantum integral and is called 2-generation. We show that there are quantum measures that 2-generate coevents, but do not 1-generate coevents. Examples also show that there are coevents that are 2-generated but not 1-generated. For simplicity only finite systems are considered.
Direct band gap GaP nanowires predicted through first principles
Authors: Santos Charley B. E. , Schmidt T. M.
Published: November 2010

GaP nanowire, a potential material for new devices where optical and electronic applications can be merged, suffers some limitations because it presents indirect band gap. Using first principles calculations we demonstrate that, due to confinement effects, the band gap not only is enlarged when in a nanowire form, but can be transformed to a direct band gap semiconductor nanowire, just by reducing the nanowire diameter to few nanometers. This transition to a direct band gap is obtained for [111] oriented GaP nanowires but not for [110] oriented nanowires. The effects of surface states which can alter the band gap have been studied with hydrogen saturation and an oxide cap layer on the surface of the GaP nanowire. The results show that, while the hydrogen is a perfect passivator, the GaP/Ga2O3 heterojunction presents a small conduction band offset but keeps direct band gap [111] oriented GaP nanowires.
Liquid crystal-ZnO nanoparticle photovoltaics: Role of nanoparticles in ordering the liquid crystal
Authors: Martínez-Miranda L. J. , Traister Kaitlin M. , Meléndez-Rodríguez Iriselies , Salamanca-Riba Lourdes
Published: November 2010

We investigate the role that order plays in the transfer of charges in the ZnO nano-particle-octylcyanobiphenyl (8CB) liquid crystal system, considered for photovoltaic applications. We have changed the concentration of ZnO nanoparticles in 8CB from 1.18 to 40 wt %. Our results show an improvement in the alignment of the liquid crystal with increasing weight percentage of ZnO nanoparticles, up to a concentration of 30 wt %. In addition, the current generated by the system increases by three orders of magnitude.
Modeling and optimization of white paint back reflectors for thin-film silicon solar cells
Authors: Lipovšek Benjamin , Krč Janez , Isabella Olindo , Zeman Miro , Topič Marko
Published: November 2010

Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-film solar cells. The parameters of white paint, such as the paint film thickness, the pigment volume concentration (PVC), and the pigment/binder refractive index ratio (RIR), are examined and optimized to achieve the required optical properties for back reflector application. The simulation trends indicate that white paint back reflectors with sufficient film thickness and higher PVC and RIR values exhibit improved reflectivity characteristics which results in an increased long-wavelength quantum efficiency of thin-film silicon solar cells. The simulation results based on the 1D model agree very well with the experimental data obtained from reflectance measurements of various white paint compositions and quantum efficiency measurements of amorphous silicon solar cells with white paint back reflectors.
Theory of absorption rate of carriers in fused silica under intense laser irradiation
Authors: Deng H. X. , Xiang X. , Zheng W. G. , Yuan X. D. , Wu S. Y. , Jiang X. D. , Gao F. , Zu X. T. , Sun K.
Published: November 2010

A nonperturbative quantum theory for phonon-assisted photon absorption of conduction band electron in intense laser was developed. By carrying out the calculation in fused silica at wavelengths from ultraviolet to infrared in terawatt intensity laser, we show that the nonperturbation approach can make a uniform description of energy absorption rate at both short wavelengths and long wavelengths on terawatt per centimeter square intensity laser.
Molecular vibration spectroscopy study of irradiation effect in C60 films induced by low energy ion
Authors: Yun-Chong Fu , Yun-Fan Jin
Published: November 2010

Irradiation effect in C60 films induced by 170 keV B ion was investigated by means of Fourier transform infrared (FTIR) and Raman spectroscopies. The damage cross section σ and the effective damage radius R are deduced from the experimental data of all four IR active modes and evident four Raman active modes of C60 molecule. The differences on irradiation sensitivity and structural stability of the different active modes of C60 molecule are compared. The results indicate that T1u (4) of infrared active mode and Ag (1) of Raman active mode are most sensitive for B ion irradiation. On the other hand T1u (2) of infrared active mode and Hg (3) of Raman active mode are comparatively stable under B ion irradiation.
Nonvolatile and unipolar resistive switching characteristics of pulsed laser ablated NiO films
Authors: Panda D. , Dhar A. , Ray S. K.
Published: November 2010

Unipolar nonvolatile resistive switching memory properties of pulse laser ablated nickel oxide films have been studied. Grazing incidence x-ray diffraction and electron diffraction spectra of the oxide films reveal polycrystalline nature of deposited NiO films. Cross-sectional transmission electron micrograph shows a fairly uniform oxide surface. The rms surface roughnesses of deposited oxides have been studied as a function of annealing temperature using atomic force microscopy. By applying a proper voltage bias and compliance, Pt/NiO/Pt structures exhibited unipolar resistive switching having a very low SET and RESET voltages. The OFF state resistance and SET voltage are found to increase with the increase in annealing temperature. The ratio between the two resistance states can be as high as 1000. The current conduction phenomena at two resistance states have been studied. The switching phenomena have been explained using the rupture and formation of conducting filaments. The effect of postdeposition annealing on the resistance switching properties is discussed.
Gibbs random graphs on point processes
Authors: Ferrari Pablo A. , Pechersky Eugene A. , Sisko Valentin V. , Yambartsev Anatoly A.
Published: November 2010

Consider a discrete locally finite subset Γ of \documentclass[12pt]{minimal}\begin{document}${\mathbb R}^d$\end{document}Rd and the complete graph (Γ, E), with vertices Γ and edges E. We consider Gibbs measures on the set of sub-graphs with vertices Γ and edges E′⊂E. The Gibbs interaction acts between open edges having a vertex in common. We study percolation properties of the Gibbs distribution of the graph ensemble. The main results concern percolation properties of the open edges in two cases: (a) when Γ is sampled from a homogeneous Poisson process; and (b) for a fixed Γ with sufficiently sparse points.
Effect of top metal contact on electrical transport through individual multiwalled carbon nanotubes
Authors: Kulshrestha Neha , Misra Abhishek , Srinivasan Senthil , Hazra Kiran Shankar , Bajpai Reeti , Roy Soumyendu , Vaidya Gayatri , Misra D. S.
Published: November 2010

The effect of position of top metal contact on the electrical transport through individual multiwalled carbon nanotubes (MWNTs) has been investigated using gas injection system in situ in scanning electron microscope to deposit the top platinum metal contacts at different desired sites on the side contacted MWNTs in bridging structure. Current-voltage measurements reveal a significant improvement in electrical properties of the tubes after the top contact is made. This improvement has been found to be independent of position of top contact, i.e., whether the top contact is made on the ends or at any other site of the tube.
Chemical coating of large-area Au nanoparticle two-dimensional arrays as plasmon-resonant optics
Authors: Isozaki Katsuhiro , Ochiai Takao , Taguchi Tomoya , Nittoh Koh-ichi , Miki Kazushi
Published: November 2010

Innovative nanophotonic applications require a technique for generating not a nanometer-scale point but a large-area (mm2−m2) near-field light source. We succeeded in developing a large-area near-field light source that is densely constructed of uniform-size gold nanoparticles (AuNPs) two-dimensionally arrayed with regular interparticle gaps, which has tunable localized surface plasmon resonance bands (600–1100 nm). The near-field excitation properties based on the optical tunability of the AuNP two-dimensional arrays demonstrate that our chemical coating of large-area near-field light sources is widely applicable such as for high-sensitivity optical sensors and high-efficiency solar cells.
Strain response of La0.7Sr0.3CoO3 epitaxial thin films probed by SrTiO3 crystalline microcantilevers
Authors: Biasotti M. , Pellegrino L. , Bellingeri E. , Manca N. , Siri A. S. , Marrè D.
Published: December 2010

We investigate the effect of tensile strain on the resistivity of La0.7Sr0.3CoO3 thin films grown on SrTiO3 microcantilevers. Strain is applied by bending the microcantilevers both mechanically through an atomic force microscope tip and electrostatically. A strain gauge factor of 12 is observed, similar to the value measured for manganite thin films. Such low value evidences the role of extrinsic effects in the cobaltites giant gauge factor observed by other authors.
Demonstration of laser action in a pseudorandom medium
Authors: Yang Jin-Kyu , Boriskina Svetlana V. , Noh Heeso , Rooks Michael J. , Solomon Glenn S. , Dal Negro Luca , Cao Hui
Published: November 2010

We demonstrated lasing in localized optical resonances of deterministic aperiodic structures with pseudorandom morphologies. The localized lasing modes in two-dimensional arrays of air nanoholes in GaAs membranes occur at reproducible spatial locations, and their frequencies are only slightly affected by the structural fluctuations in different samples. A numerical study on the resonances of the passive systems and optical imaging of lasing modes enabled us to interpret the observed lasing behavior in terms of distinctive localized resonances in the two-dimensional pseudorandom structures.
Thickness-dependent structural and magnetic properties of BiFeO3 films prepared by metal organic decomposition method
Authors: Huang Fengzhen , Lu Xiaomei , Lin Weiwei , Kan Yi , Zhang Junting , Chen Qingdong , Wang Zhe , Li Liben , Zhu Jinsong
Published: December 2010

Perovskite BiFeO3 films with various thicknesses were prepared on Pt/Ti/SiO2/Si substrates by metal organic decomposition method. It was found that, with the film thickness increasing from 35 to 120 nm, the grain and ferroelectric domain size slightly increased, while the saturation magnetization Ms abruptly decreased. For the further increase of film thickness, Ms decreased slowly and the magnetization of unit area exhibited a fluctuation behavior. Moreover, the magnetic anisotropy degenerated with the increase of film thickness. The possible causes for the thickness effects were discussed.
Electrical and kinetical aspects of homogeneous dielectric-barrier discharge in xenon for excimer lamps
Authors: Belasri A. , Harrache Z.
Published: December 2010

A pulsed dielectric-barrier discharge in xenon has been simulated for operating conditions typical to excimer lamps, in which the discharge is considered spatially homogeneous. The computer model developed is based on the xenon plasma chemistry, the circuit, and the Boltzmann equations. First, the validity of the physical model was checked and compared to experimental and theoretical works, and then the model is applied in the case of a sinusoidal voltage at period frequencies in the range of 50 kHz–2 MHz. The results obtained with the present description are in good agreement with experimental measurements and one-dimensional fluid prediction in terms of electrical characteristics and vacuum ultraviolet (vuv) emission. The effect of operation voltage, power source frequency, dielectric capacitance, as well as gas pressure on the discharge efficiency and the 172, 150, and 147 nm photon generation, under the typical experimental operating conditions and for the case of a sinusoidal applied voltage, have been investigated and discussed. Calculations suggest that the overall conversion efficiency from electrical energy to vuv emission in the lamp is greater than 38%, and it will be very affected at high power source frequency and high gas pressure with a significant dependence on the dielectric capacitance.
Lensfree sensing on a microfluidic chip using plasmonic nanoapertures
Authors: Khademhosseinieh Bahar , Biener Gabriel , Sencan Ikbal , Su Ting-Wei , Coskun Ahmet F. , Ozcan Aydogan
Published: December 2010

We demonstrate lensfree on-chip sensing within a microfluidic channel using plasmonic nanoapertures that are illuminated by a partially coherent quasimonochromatic source. In this approach, lensfree diffraction patterns of metallic nanoapertures located at the bottom of a microfluidic channel are recorded using an optoelectronic sensor-array. These lensfree diffraction patterns can then be rapidly processed, using phase recovery techniques, to back propagate the optical fields to an arbitrary depth, creating digitally focused complex transmission patterns. Cross correlation of these patterns enables lensfree on-chip sensing of the local refractive index surrounding the near-field of the plasmonic nanoapertures. Based on this principle, we experimentally demonstrate lensfree sensing of refractive index changes as small as ∼2×10−3. This on-chip sensing approach could be quite useful for development of label-free microarray technologies by multiplexing thousands of plasmonic structures on the same microfluidic chip, which can significantly increase the throughput of sensing.
Chaos from turbulence: Stochastic-chaotic equilibrium in turbulent convection at high Rayleigh numbers
Authors: Bershadskii A.
Published: November 2010

It is shown that the correlation function of the mean wind velocity generated by a turbulent thermal convection (Rayleigh number Ra∼1011) exhibits exponential decay with a very long correlation time, while the corresponding largest Lyapunov exponent is certainly positive. These results together with the reconstructed phase portrait indicate the possible presence of chaotic component in the examined mean wind. Telegraph approximation is also used to study the relative contribution of the chaotic and stochastic components to the mean wind fluctuations and an equilibrium between these components has been studied in detail.
Invar effects of (Fe71.2B24Y4.8)96Nb4 alloy in different structural states
Authors: Hu Qiang , Zeng Xie-Rong , Fu Ming-Wang
Published: December 2010

This paper reports the observation of the clear Invar effects of (Fe71.2B24Y4.8)96Nb4 bulk metallic glass. The Invar effects of (Fe71.2B24Y4.8)96Nb4 alloys in different structural states are also investigated in situ through cyclic thermal dilation tests at different cyclic temperatures. The results show that these Invar effects are strengthened in the relaxation amorphous state, weakened in the nanocrystalline state, and absent in the complete crystalline state. X-ray diffraction and Mössbauer spectroscopy demonstrate that the structural influences on Invar effects can be explained by the different local atomic arrangements around Fe atoms in different structural states.
Profilin1 regulates PI(3,4)P
2
and lamellipodin accumulation at the leading edge thus influencing motility of MDA-MB-231 cells
Authors: Bae Yong Ho , Ding Zhijie , Das Tuhin , Wells Alan , Gertler Frank , Roy Partha
Published: November 2010

Profilin1, a ubiquitously expressed actin-binding protein, plays a critical role in cell migration through actin cytoskeletal regulation. Given the traditional view of profilin1 as a promigratory molecule, it is difficult to reconcile observations that profilin1 is down-regulated in various invasive adenocarcinomas and that reduced profilin1 expression actually confers increased motility to certain adenocarcinoma cells. In this study, we show that profilin1 negatively regulates lamellipodin targeting to the leading edge in MDA-MB-231 breast cancer cells and normal cells; profilin1 depletion increases lamellipodin concentration at the lamellipodial tip (where it binds Ena/VASP), and this mediates the hypermotility. We report that the molecular mechanism underlying profilin1’s modulation of lamellipodin localization relates to phosphoinositide control. Specifically, we show that phosphoinositide binding of profilin1 inhibits the motility of MDA-MB-231 cells by negatively regulating PI(3,4)P
2
at the membrane and thereby limiting recruitment of lamellipodin [a PI(3,4)P
2
-binding protein] and Ena/VASP to the leading edge. In summary, this study uncovers a unique biological consequence of profilin1-phosphoinositide interaction, thus providing direct evidence of profilin1’s regulation of cell migration independent of its actin-related activity.
Global capacity for emerging infectious disease detection
Authors: Chan Emily H. , Brewer Timothy F. , Madoff Lawrence C. , Pollack Marjorie P. , Sonricker Amy L. , Keller Mikaela , Freifeld Clark C. , Blench Michael , Mawudeku Abla , Brownstein John S.
Published: November 2010

The increasing number of emerging infectious disease events that have spread internationally, such as severe acute respiratory syndrome (SARS) and the 2009 pandemic A/H1N1, highlight the need for improvements in global outbreak surveillance. It is expected that the proliferation of Internet-based reports has resulted in greater communication and improved surveillance and reporting frameworks, especially with the revision of the World Health Organization's (WHO) International Health Regulations (IHR 2005), which went into force in 2007. However, there has been no global quantitative assessment of whether and how outbreak detection and communication processes have actually changed over time. In this study, we analyzed the entire WHO public record of
Disease Outbreak News
reports from 1996 to 2009 to characterize spatial-temporal trends in the timeliness of outbreak discovery and public communication about the outbreak relative to the estimated outbreak start date. Cox proportional hazards regression analyses show that overall, the timeliness of outbreak discovery improved by 7.3% [hazard ratio (HR) = 1.073, 95% CI (1.038; 1.110)] per year, and public communication improved by 6.2% [HR = 1.062, 95% CI (1.028; 1.096)] per year. However, the degree of improvement varied by geographic region; the only WHO region with statistically significant (α = 0.05) improvement in outbreak discovery was the Western Pacific region [HR = 1.102 per year, 95% CI (1.008; 1.205)], whereas the Eastern Mediterranean [HR = 1.201 per year, 95% CI (1.066; 1.353)] and Western Pacific regions [HR = 1.119 per year, 95% CI (1.025; 1.221)] showed improvement in public communication. These findings provide quantitative historical assessment of timeliness in infectious disease detection and public reporting of outbreaks.
Antarctic lakes suggest millennial reorganizations of Southern Hemisphere atmospheric and oceanic circulation
Authors: Hall Brenda L. , Denton George H. , Fountain Andrew G. , Hendy Chris H. , Henderson Gideon M.
Published: November 2010

The phasing of millennial-scale oscillations in Antarctica relative to those elsewhere in the world is important for discriminating among models for abrupt climate change, particularly those involving the Southern Ocean. However, records of millennial-scale variability from Antarctica dating to the last glacial maximum are rare and rely heavily on data from widely spaced ice cores, some of which show little variability through that time. Here, we present new data from closed-basin lakes in the Dry Valleys region of East Antarctica that show high-magnitude, high-frequency oscillations in surface level during the late Pleistocene synchronous with climate fluctuations elsewhere in the Southern Hemisphere. These data suggest a coherent Southern Hemisphere pattern of climate change on millennial time scales, at least in the Pacific sector, and indicate that any hypothesis concerning the origin of these events must account for synchronous changes in both high and temperate latitudes.
Evolution of an antifreeze protein by neofunctionalization under escape from adaptive conflict
Authors: Deng Cheng , Cheng C.-H. Christina , Ye Hua , He Ximiao , Chen Liangbiao
Published: November 2010

The evolutionary model escape from adaptive conflict (EAC) posits that adaptive conflict between the old and an emerging new function within a single gene could drive the fixation of gene duplication, where each duplicate can freely optimize one of the functions. Although EAC has been suggested as a common process in functional evolution, definitive cases of neofunctionalization under EAC are lacking, and the molecular mechanisms leading to functional innovation are not well-understood. We report here clear experimental evidence for EAC-driven evolution of type III antifreeze protein gene from an old sialic acid synthase (
SAS
) gene in an Antarctic zoarcid fish. We found that an
SAS
gene, having both sialic acid synthase and rudimentary ice-binding activities, became duplicated. In one duplicate, the N-terminal
SAS
domain was deleted and replaced with a nascent signal peptide, removing pleiotropic structural conflict between SAS and ice-binding functions and allowing rapid optimization of the C-terminal domain to become a secreted protein capable of noncolligative freezing-point depression. This study reveals how minor functionalities in an old gene can be transformed into a distinct survival protein and provides insights into how gene duplicates facing presumed identical selection and mutation pressures at birth could take divergent evolutionary paths.
Identification of 9-
cis
-retinoic acid as a pancreas-specific autacoid that attenuates glucose-stimulated insulin secretion
Authors: Kane Maureen A. , Folias Alexandra E. , Pingitore Attilio , Perri Mariarita , Obrochta Kristin M. , Krois Charles R. , Cione Erika , Ryu Joo Yeon , Napoli Joseph L.
Published: November 2010

The
all-trans
-retinoic acid (atRA) isomer, 9-
cis
-retinoic acid (9cRA), activates retinoic acid receptors (RARs) and retinoid X receptors (RXRs) in vitro. RARs control multiple genes, whereas RXRs serve as partners for RARs and other nuclear receptors that regulate metabolism. Physiological function has not been determined for 9cRA, because it has not been detected in serum or multiple tissues with analytically validated assays. Here, we identify 9cRA in mouse pancreas by liquid chromatography/tandem mass spectrometry (LC/MS/MS), and show that 9cRA decreases with feeding and after glucose dosing and varies inversely with serum insulin. 9cRA reduces glucose-stimulated insulin secretion (GSIS) in mouse islets and in the rat β-cell line 832/13 within 15 min by reducing glucose transporter type 2 (Glut2) and glucokinase (GK) activities. 9cRA also reduces
Pdx-1
and
HNF4
α mRNA expression, ∼8- and 80-fold, respectively: defects in
Pdx-1
or
HNF4α
cause maturity onset diabetes of the young (MODY4 and 1, respectively), as does a defective GK gene (MODY2). Pancreas β-cells generate 9cRA, and mouse models of reduced β-cell number, heterozygous Akita mice, and streptozotocin-treated mice have reduced 9cRA. 9cRA is abnormally high in glucose-intolerant mice, which have β-cell hypertropy, including mice with diet-induced obesity (DIO) and
ob/ob
and
db/db
mice. These data establish 9cRA as a pancreas-specific autacoid with multiple mechanisms of action and provide unique insight into GSIS.