bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrahigh‐resolution seismic reflection imaging of the Alpine Fault, New Zealand
Authors: Kaiser A. E. , Green A. G. , Campbell F. M. , Horstmeyer H. , Manukyan E. , Langridge R. M. , McClymont A. F. , Mancktelow N. , Finnemore M. , Nobes D. C.
Published: November 2009

High‐resolution seismic reflection surveys across active fault zones are capable of supplying key structural information required for assessments of seismic hazard and risk. We have recorded a 360 m long ultrahigh‐resolution seismic reflection profile across the Alpine Fault in New Zealand. The Alpine Fault, a continental transform that juxtaposes major tectonic plates, is capable of generating large (M > 7.8) damaging earthquakes. Our seismic profile across a northern section of the fault targets fault zone structures in Holocene to late Pleistocene sediments and underlying Triassic and Paleozoic basement units from 3.5 to 150 m depth. Since ultrashallow seismic data are strongly influenced by near‐surface heterogeneity and source‐generated noise, an innovative processing sequence and nonstandard processing parameters are required to produce detailed information on the complex alluvial, glaciofluvial and glaciolacustrine sediments and shallow to steep dipping fault‐related features. We present high‐quality images of structures and deformation within the fault zone that extend and complement interpretations based on shallow paleoseismic and ground‐penetrating radar studies. Our images demonstrate that the Alpine Fault dips 75°–80° to the southeast through the Quaternary sediments, and there is evidence that it continues to dip steeply between the shallow basement units. We interpret characteristic curved basement surfaces on either side of the Alpine Fault and deformation in the footwall as consequences of normal drag generated by the reverse‐slip components of displacement on the fault. The fault dip and apparent ∼35 m vertical offset of the late Pleistocene erosional basement surface across the Alpine Fault yield a provisional dip‐slip rate of 2.0 ± 0.6 mm/yr. The more significant dextral‐slip rate cannot be determined from our seismic profile.
Strong southward transport events due to typhoons in the Taiwan Strait
Authors: Zhang Wen‐Zhou , Hong Hua‐Sheng , Shang Shao‐Ping , Yan Xiao‐Hai , Chai Fei
Published: November 2009

Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon‐generated local wind stress and/or along‐strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along‐strait momentum gradient was insignificant.
Growth kinetics of Ge crystals on silicon oxide by nanoscale silicon seed induced lateral epitaxy
Authors: Cammilleri V. D. , Yam V. , Fossard F. , Renard C. , Bouchier D. , Fazzini P. F. , Hÿtch M.
Published: November 2009

In this paper, we present our studies on the growth kinetics of Ge crystals on silicon oxide by nanoscale seed induced lateral epitaxy. We propose a simple and reliable method based on standard local oxidation of silicon technique for creating nanoscale silicon seeds at the edge of thermally grown silicon oxide stripes of desired thickness. The growth of Ge from germane is initiated in the two silicon seed lines and evolves toward a complete wetting of the SiO2 stripe after coalescence. The wetting mechanism of SiO2 by Ge is strongly dependent on the seed orientation and closely related to the development of {111} facets. The coalescence of adjacent Ge crystals results in an improvement in the organization of the initial material. As a result, no defect is visible in the inner part of the structure. The observed defects are arrays of misfit dislocations standing along the seed lines, while only few dislocations are visible through the Ge crystal. Geometric phase analysis of high resolution transmission electron microscopy images and x-ray diffraction reciprocal space maps show that the so-grown Ge crystal stripes on SiO2 layer are fully relaxed, homogeneous, and fully coherent along their length. The main deviation regarding a perfect epitaxial relation with the silicon substrate is a tilt of ±0.6° around the longitudinal axis of stripe crystals.
Photoacoustic beam profiling of pulsed lasers
Authors: González Martín , Santiago Guillermo , Slezak Verónica , Peuriot Alejandro
Published: November 2009

We introduce a beam profiler of pulsed lasers based on the photoacoustic technique. The method assumes that the initial pressure distribution inside the acoustic cell follows the laser intensity pattern if absorbed energy relaxes rapidly. This initial pressure condition can be described as a superposition of acoustic modes of different amplitudes and phases. We analyze how to reconstruct the intensity profile of the laser beam from the recorded acoustic signals. Finally, we present preliminary results obtained with a frequency doubled Nd:YAG laser that excites NO2–CF2Cl2 mixtures.
Nucleation in a Potts lattice gas model of crystallization from solution
Authors: Duff Nathan , Peters Baron
Published: November 2009

Nucleation from solution is important in many pharmaceutical crystallization, biomineralization, material synthesis, and self-assembly processes. Simulation methodology has progressed rapidly for studies of nucleation in pure component and implicit solvent systems; however little progress has been made in the simulation of explicit solvent systems. The impasse stems from the inability of rare events simulation methodology to be combined with simulation techniques which maintain a constant chemical potential driving force (supersaturation) for nucleation. We present a Potts lattice gas (PLG) to aid in the development of new simulation strategies for nucleation from solution. The PLG captures common crystallization phase diagram features such as a eutectic point and solute/solvent melting points. Simulations of the PLG below the bulk solute melting temperature reveal a competition between amorphous and crystalline nuclei. As the temperature is increased toward the bulk melting temperature, the nucleation pathway changes from a one step crystalline nucleation pathway to a two step pathway, where an amorphous nucleus forms and then crystallizes. We explain these results in terms of classical nucleation theory with different size-dependant chemical potentials for the amorphous and crystalline nucleation pathways. The two step pathway may be particularly important when crystallization is favored only at postcritical sizes.
Stage for texture measurements above room temperature in a Philips X’Pert Pro MPD diffractometer
Authors: Sobrero César E. , Castellani Daniel , Bolmaro Raúl E. , Malarría Jorge A.
Published: November 2009

A special stage for texture measurements above room temperature was designed with the proper size and weight to be fitted onto the Eulerean cradle of the Philips X’Pert Pro MPD diffractometer. With such device, flat samples of 2×2 cm2 area can be analyzed at a nearly constant temperature with variations below ±4 °C in the range between ambient temperature and 200 °C.
Tidal flow over three-dimensional topography in a stratified fluid
Authors: King Benjamin , Zhang H. P. , Swinney Harry L.
Published: November 2009

Our laboratory experiments and numerical simulations of stratified tidal flow past model topography (a half sphere on a horizontal plane) reveal several three-dimensional flow features, including an unexpected flow perpendicular to the forcing plane (the vertical plane through the center of the sphere, in the direction of the oscillating tide). This perpendicular flow has a time-independent component and a component oscillating at twice the tidal frequency. Our results show that the time-independent part of the perpendicular flow forms a large-scale horizontal circulation, which could enhance material transport and mixing near bottom topography in the oceans. In addition, for small forcing amplitude we find that the azimuthal dependence of the internal wave field is described by the functional form cos ϕ, as predicted by linear inviscid theory. At higher forcing amplitude, the internal wave energy is more concentrated in the forcing direction. Finally, we observe a wave intensity asymmetry in the polar direction and explain the asymmetry using a geometrical argument.
Resistive switching in aluminum/anodized aluminum film structure without forming process
Authors: Zhu W. , Chen T. P. , Liu Z. , Yang M. , Liu Y. , Fung S.
Published: November 2009

Metal-insulator-metal (MIM) structure was fabricated by partially anodizing aluminum film followed by deposition of another aluminum film. Unipolar resistive switching between a high-resistance state and a low-resistance state with a high resistance ratio (>∼104) was observed from the structure. The switching occurred without the requirement of a forming process, which was attributed to the pre-existing conductive filaments in the Al-rich AlxOy layer formed by the anodization. Each resistance state exhibited Ohmic behavior which could be explained by the metallic conduction and electron hopping from one isolated state to the next in the Al-rich AlxOy layer. The MIM structure showed good memory characteristics.
Hydrogen induced lattice expansion and crystallinity degradation in palladium nanoparticles: Effect of hydrogen concentration, pressure, and temperature
Authors: Khanuja Manika , Mehta B. R. , Agar Pragya , Kulriya P. K. , Avasthi D. K.
Published: November 2009

A detailed structural study involving in situ glancing angle x-ray diffraction (GAXRD) analysis carried out on Pd nanoparticle and thin film samples at hydrogen concentrations of 2%, 5%, and 10% over temperature ranging from −100 to 55 °C and hydrogen pressures ranging from 250 to 1000 mbars is reported. Variation in the lattice constant has been interpreted in terms of hydrogen content in α and β PdHx phases, and decrease in XRD peak intensity has been interpreted in terms of hydrogen induced degradation in crystalline quality and temperature induced lattice disorder. It is observed that Pd–H interaction is strongly influenced by the temperature and pressure dependences of physisorption, chemisorption, and diffusion. These results show that the increased surface area, interparticle gaps, and electronic enhancement result in enhanced Pd–H interaction in case of nanoparticles. In addition, the presence of single β phase and lower crystallinity degradation is observed in the case of Pd nanoparticles in comparison to thin films. The above mentioned differences between nanoparticles and thin films are more pronounced at lower temperatures due to the increased presence of subsurface sites.
Towards quantum mechanical description of the unconventional mass-dependent isotope effect in ozone: Resonance recombination in the strong collision approximation
Authors: Grebenshchikov S. Yu. , Schinke R.
Published: November 2009

The dependence of ozone recombination rate on the masses of oxygen isotopes is examined in the strong collision approximation by means of quantum mechanical calculations of resonance spectra of several rotating isotopomers. The measured ΔZPE effect and its temperature dependence can be reconstructed from partial widths of narrow nonoverlapping resonances. The effect is attributed to substantial contributions of highly rotationally excited states to recombination.
Multiple enhanced transmission bands through compound periodic array of rectangular holes
Authors: Liu Jian-Qiang , Chao Xing-Bing , Wei Jian-Ning , He Meng-Dong , Wang Ling-Ling , Wan Qing , Wang Yu
Published: November 2009

Based on the finite-difference time-domain method, we demonstrate multiple enhanced transmission bands through subwavelength compound periodic array of rectangular holes by adjusting the cutoff wavelength of each hole. The results show that the transmission spectrum of this structure is almost a compound of that of the corresponding periodic hole arrays with simple cell, when the holes are arranged appropriately. It is also found that the surface plasmon resonance peak and the localized resonance peak exhibit different behaviors as the symmetry of compound periodic structure varies. The proposed method provides an effective way to achieve enhanced transmission simultaneously at different selected wavelengths in the visible and infrared regions.
Structure of orthorhombic martensitic phase in binary Ti–Nb alloys
Authors: Banumathy S. , Mandal R. K. , Singh A. K.
Published: November 2009

The structure of orthorhombic (α″) martensitic phase of Ti–8Nb, Ti–12Nb, and Ti–16Nb alloys has been investigated using Rietveld refinement of x-ray diffraction data. The chemical analysis data have been used to determine the site occupancy of initial models. A limit of the Wyckoff positions has been proposed based on the symmetry of the Cmcm space group, which allows the movement of atoms without breaking the space group symmetry. This has also been incorporated in the initial models of experimental alloys, and accordingly Wyckoff positions have been refined. It has been observed that the atoms move along the Y-axis (parallel to the b-axis) and the movement of atoms increases with increase in Nb concentration. The formation of orthorhombic (α″) phase has been explained based on the movement of atoms along the Y-axis. This in turn breaks the hexagonal symmetry and forms an orthorhombic phase.
Repetitive production of positron emitters using deuterons accelerated by multiterawatt laser pulses
Authors: Fujimoto Masatoshi , Matsukado Koji , Takahashi Hironori , Kawada Yoichi , Ohsuka Shinji , Aoshima Shin-Ichiro
Published: November 2009

Positron emitters C11, N13, and O15, which can be used in positron emission tomography, were produced using deuterons accelerated by irradiation of laser pulses ∼70 TW in peak power and ∼30 fs in duration with a repetition of 10 Hz during a period of as long as 200 s. Every laser pulse irradiates the fresh surface of a long strip of a solid-state thin film. Deuterons contained in the film are accelerated in the relativistic plasma induced by the pulse. The deuterons are repetitively incident on solid plates, which are placed near the film, to produce positron emitters by nuclear reactions. The radioactivities of the activated plates are measured after the termination of laser irradiation. In activation of graphite, boron-nitride, and melamine plates, the products had total activities of 64, 46, and 153 Bq, respectively. Contamination in the setup was negligible even after several thousands of laser shots. Our apparatus is expected to greatly contribute to the construction of a compact PET diagnostic system in the future.
Multiparameter deformation theory for quantum confined systems
Authors: Aleixo A. N. F. , Balantekin A. B.
Published: November 2009

We introduce a generalized multiparameter deformation theory applicable to all supersymmetric and shape-invariant systems. Taking particular choices for the deformation factors used in the construction of the deformed ladder operators, we show that we can generalize the one-parameter quantum-deformed harmonic oscillator models and build alternative multiparameter deformed models that are also shape invariant like the primary undeformed system.
Effects of pressure on charge transport and magnetic properties of La1.32Sr1.68Mn2O7 layered manganite
Authors: Kumaresavanji M. , Reis M. S. , Xing Y. T. , Fontes M. B.
Published: November 2009

We have studied the effects of hydrostatic pressure on the electrical transport and magnetic properties of La1.32Sr1.68Mn2O7 layered manganite up to 25 kbars. At ambient pressure, the compound exhibits a ferromagnetic transition accompanied by a metal-insulator transition (TMI1) at 118 K. Increasing pressure induces a second metal-insulator (TMI2) transition at a critical pressure of 6≤PC≤7 kbars in the temperature dependence of resistivity measurement. With further increase in pressure, both TMI1 and TMI2 shift to higher temperatures continuously, however, displaying a suppression in the amplitude of the peaks on the resistivity curves. We could not observe any transition corresponding to TMI2 in the temperature dependence of magnetization measurement under pressures up to 10 kbars. However, pressure reduces the magnetic moments at low temperatures and shifts the TC to higher temperatures at the same rate observed for TMI1. A large negative tunneling magnetoresistance was observed around TC due to the applied magnetic field up to the maximum available value of 5 T, and the pressure reduces the magnetoresistance ratio significantly. This result is due to the canted ferromagnetic order that was established by increasing pressure, which leads to an electron localized ferromagnetic insulating phase.
Periodically poled KTiOAsO4 for highly efficient midinfrared optical parametric devices
Authors: Zukauskas Andrius , Thilmann Nicky , Pasiskevicius Valdas , Laurell Fredrik , Canalias Carlota
Published: November 2009

We demonstrate high pattern-fidelity periodic poling of KTiOAsO4 at room temperature. The periodically poled crystal shows a deff of 10.1 pm/V and is used in an optical parametric oscillator pumped at 1064 nm to generate parametric radiation at 1538 and 3452 nm with a conversion efficiency of 45%.
An empirical potential based quasicontinuum theory for structural prediction of water
Authors: Raghunathan A. V. , Aluru N. R.
Published: November 2009

An empirical potential based quasicontinuum theory (EQT) is proposed to predict the structure, concentration, and various potential profiles of water in confined environments. EQT seamlessly unifies the continuum theory given by the Nernst–Planck equation and the atomistic theory governed by interatomic potentials. In particular, the interatomic potentials describing various interactions in water are directly incorporated into the Nernst–Planck theory. We introduce a new empirical potential to compute electrostatic interactions in water. The results from the EQT formalism are compared with molecular dynamics simulations and a good match is observed for channels with widths ranging from 2σow to 20σow, where σow is the water-oxygen Lennard-Jones distance parameter. While molecular dynamics can be limited to small length scales, EQT can be used at various length scales to effectively and accurately capture both the interfacial structure and bulk properties of water making it a robust and fast method that can predict properties in widths ranging from the macroscale down to the nanoscale.

At the request of the authors and editor, this article is being retracted effective 26 March 2010.
Molecular dynamics simulations of glycine crystal-solution interface
Authors: Banerjee Soumik , Briesen Heiko
Published: November 2009

Glycine is an amino acid that has several applications in the pharmaceutical industry. Hence, growth of α-glycine crystals through solution crystallization is an important process. To gain a fundamental understanding of the seeded growth of α-glycine from aqueous solution, the (110) face of α-glycine crystal in contact with a solution of glycine in water has been simulated with molecular dynamics. The temporal change in the location of the interface of the α-glycine crystal seed has been characterized by detecting a density gradient. It is found that the α-glycine crystal dissolves with time at a progressively decreasing rate. Diffusion coefficients of glycine adjacent to (110) face of α-glycine crystal have been calculated at various temperatures (280, 285, 290, 295, and 300 K) and concentrations (3.6, 4.5, and 6.0 mol/l) and compared to that in the bulk solution. In order to gain a fundamental insight into the nature of variation in such properties at the interface and the bulk, the formation of hydrogen bonds at various temperatures and concentrations has been investigated. It is found that the nature of interaction between various atoms of glycine molecules, as characterized by radial distribution functions, can provide interesting insight into the formation of hydrogen bonds that in turn affect the diffusion coefficients at the interface.
A tunable few electron triple quantum dot
Authors: Gaudreau L. , Kam A. , Granger G. , Studenikin S. A. , Zawadzki P. , Sachrajda A. S.
Published: November 2009

In this paper, we report on a tunable few electron lateral triple quantum dot design. The quantum dot potentials are arranged in series. The device is aimed at studies of triple quantum dot properties where knowing the exact number of electrons is important as well as quantum information applications involving electron spin qubits. We demonstrate tuning strategies for achieving required resonant conditions such as quadruple points where all three quantum dots are on resonance. We find that in such a device resonant conditions at specific configurations are accompanied by complex charge transfer behavior.
Generalizations of the Young–Laplace equation for the pressure of a mechanically stable gas bubble in a soft elastic material
Authors: Goldman Saul
Published: November 2009

The Young–Laplace equation for the pressure of a mechanically stable gas bubble is generalized to include the effects of both surface tension and elastic forces of its surroundings. The latter are taken to be comprised of a soft isotropic material. Generalizations are derived for conditions of constant external pressure and constant system volume. The derived equations are formally exact for a spherical bubble surrounded by a spherical shell of isotropic material, provided that the bubble is sufficiently large for the surface tension to be treated macroscopically, and that the bubble radius is much larger than the thickness of the bubble/soft material interface. The underlying equations are also used to derive a simple expression for the Gibbs free energy of deformation of an elastic medium that surrounds a gas bubble. The possible relevance of this expression to some recently published ideas on decompression sickness (“the bends”) is discussed.
Role of Ag-doping in small transition metal clusters from first-principles simulations
Authors: Li S. F. , Shao Zelun , Han Shuli , Xue Xinlian , Wang F. , Sun Q. , Jia Yu , Guo Z. X.
Published: November 2009

First-principles calculations are used to systematically investigate the geometric and electronic structures of both pure TMn (n=2–4) and Ag-modulated AgTMn−1 (n=2–4; 3d-transition metal (TM): from Sc to Cu; 4d-TM: from Y to Ag elements) clusters. Some new ground state structures are found for the pure TMn clusters, such as a low symmetry configuration for Cr3, which is found to be about 0.20 eV more stable than the previously reported C2v symmetry. In the most cases, Ag-doping can significantly elongate the bond lengths of the clusters and induce geometric distortions of the small clusters from the high dimensional to the low dimensional configurations. Importantly, introduction of Ag significantly changes the electronic structures of the small clusters and modulates the density of states in the proximity of the Fermi levels, which also varies with the size and the type of the cluster. The results contribute to future design of effective bimetallic alloy Ag/TM catalysts.
Undoped vacuum annealed In2O3 thin films as a transparent conducting oxide
Authors: Dixit A. , Sudakar C. , Naik R. , Naik V. M. , Lawes G.
Published: November 2009

We have investigated the structural, optical, and electrical properties of both as-grown and vacuum annealed In2O3 thin films. In contrast to the insulating as-prepared samples, vacuum annealed In2O3 films exhibit a metallic electrical conductivity with increased carrier concentration and mobility. We attribute the excess carriers to an oxygen deficiency introduced during vacuum annealing. Remarkably, these carrier densities seem to be stable under ambient conditions for at least two years. Optical spectroscopy measurements show a large optical transparency, greater than 80%, for both the as-prepared and vacuum annealed In2O3 films.
Dependence of polarization splitting on mode tuning in microcavities
Authors: Becker F. , Langner M. , Fröb H. , Lyssenko V. G. , Leo K. , Adachi C.
Published: November 2009

We present an in-depth analysis of the angle and mode tuning dependence of the polarization splitting in detuned organic microcavities. The system consists of highly reflecting dielectric mirrors comprising a continuous wedge-shaped cavity layer of 4,4′-bis(N-carbazole)-biphenyl, doped with 2 wt % of 4,4′-bis[(N-carbazole)styryl]-biphenyl as the active material. By varying the measurement position across the sample, we shift the resonant mode with respect to the center of the cavity stop band. Starting from small detunings, the splitting value increases non-linearly up to 58 meV, when the resonant modes reach the stop band edge. We compare this behavior with results from transfer matrix calculations and theoretical predictions.
Robust quantization of a molecular motor motion in a stochastic environment
Authors: Chernyak V. Y. , Sinitsyn N. A.
Published: November 2009

We explore quantization of the response of a molecular motor to periodic modulation of control parameters. We formulate the pumping-quantization theorem (PQT) that identifies the conditions for robust integer quantized behavior of a periodically driven molecular machine. Implication of PQT on experiments with catenane molecules are discussed.
The Roche Research Institute of Marine Pharmacology, 1974 - 1981: Searching for Drug Leads from Australian Marine Organisms
Authors: Rae Ian D.
Published: November 2009

In the late 1960s the Swiss pharmaceutical company Hoffmann-La Roche was attracted to the pharmacological potential of extractives from Australian marine organisms. At first the company supported the work of University of Queensland zoologist Robert Endean and work at the Great Barrier Reef Research Station on Heron Island. Within a few years, however, they severed their connection with Endean and established the Roche Research Institute of Marine Pharmacology (RRIMP) at Dee Why, New South Wales. Opened in April 1974, the Institute was led by Dr J. T. Baker, an Australian organic chemist who had researched marine natural products. State-of-the-art pharmacology was introduced with guidance from Professor Michael Rand of the University of Melbourne. The staff that Baker recruited included chemists, pharmacologists, microbiologists and marine biologists. Despite the conjecture, raised in some quarters, that RRIMP was established to mute the Australian Government's criticism of the pricing of Roche's most famous product, Valium, it is argued that the research venture was a genuine attempt to find lead compounds in organisms from Australian waters with a view to the development of new drugs. Before any such success could be achieved by RRIMP scientists, however, sweeping changes in the parent company resulted in the closure of RRIMP in mid-1981 and dispersal of its expert staff, mostly to other Australian laboratories.
Daily life of the ancient Maya recorded on murals at Calakmul, Mexico
Authors: Carrasco Vargas Ramón , López Verónica A. Vázquez , Martin Simon
Published: November 2009

Research into ancient societies frequently faces a major challenge in accessing the lives of those who made up the majority of their populations, since the available evidence so often concerns only the ruling elite. Our excavations at the ancient Maya site of Calakmul, Mexico, have uncovered a “painted pyramid:” a structure decorated with murals depicting scenes of its inhabitants giving, receiving, and consuming diverse foods, as well as displaying and transporting other goods. Many are accompanied by hieroglyphic captions that describe the participants, and include spellings of key subsistence items. Collectively, they offer insights into the social mechanisms by which goods were circulated within major Maya centers.
Biodegradable polymer nanoparticles that rapidly penetrate the human mucus barrier
Authors: Tang Benjamin C. , Dawson Michelle , Lai Samuel K. , Wang Ying-Ying , Suk Jung Soo , Yang Ming , Zeitlin Pamela , Boyle Michael P. , Fu Jie , Hanes Justin
Published: November 2009

Protective mucus coatings typically trap and rapidly remove foreign particles from the eyes, gastrointestinal tract, airways, nasopharynx, and female reproductive tract, thereby strongly limiting opportunities for controlled drug delivery at mucosal surfaces. No synthetic drug delivery system composed of biodegradable polymers has been shown to penetrate highly viscoelastic human mucus, such as non-ovulatory cervicovaginal mucus, at a significant rate. We prepared nanoparticles composed of a biodegradable diblock copolymer of poly(sebacic acid) and poly(ethylene glycol) (PSA-PEG), both of which are routinely used in humans. In fresh undiluted human cervicovaginal mucus (CVM), which has a bulk viscosity approximately 1,800-fold higher than water at low shear, PSA-PEG nanoparticles diffused at an average speed only 12-fold lower than the same particles in pure water. In contrast, similarly sized biodegradable nanoparticles composed of PSA or poly(lactic-co-glycolic acid) (PLGA) diffused at least 3,300-fold slower in CVM than in water. PSA-PEG particles also rapidly penetrated sputum expectorated from the lungs of patients with cystic fibrosis, a disease characterized by hyperviscoelastic mucus secretions. Rapid nanoparticle transport in mucus is made possible by the efficient partitioning of PEG to the particle surface during formulation. Biodegradable polymeric nanoparticles capable of overcoming human mucus barriers and providing sustained drug release open significant opportunities for improved drug and gene delivery at mucosal surfaces.
Protein kinase A and TORC1 activate genes for ribosomal biogenesis by inactivating repressors encoded by
Dot6
and its homolog
Tod6
Authors: Lippman Soyeon I. , Broach James R.
Published: November 2009

Genes required for ribosome biogenesis in yeast, referred to collectively as the Ribi regulon, are tightly regulated in coordination with nutrient availability and cellular growth rate. The promoters of a significant fraction of Ribi genes contain one or more copies of the RNA polymerases A and C (PAC) and/or ribosomal RNA-processing element (RRPE) motifs. Prompted by recent studies showing that the yeast protein Dot6 and its homolog Tod6 can bind to a PAC motif sequence in vitro and are required for efficient Ribi gene repression in response to heat shock, we have examined the role of Dot6 and Tod6 in nutrient control of Ribi gene expression in vivo. Our results indicate that PAC sites function as Dot6/Tod6-dependent repressor elements in vivo. Moreover, Dot6 and Tod6 mediate different nutrient signals, with Tod6 responsible for efficient repression of Ribi genes after inhibition of the nitrogen-sensitive TORC1 pathway and Dot6 responsible for repression after inhibition of the carbon-sensitive protein kinase A signaling pathway. Consistently, Dot6 and Tod6 are required for efficient repression of Ribi gene repression immediately after nutrient deprivation and for successful adaptation to nutrient limitation. Thus, these results establish Dot6/Tod6 as a direct link between nutrient availability, Ribi gene regulation, and growth control.
Climate, carbon cycling, and deep-ocean ecosystems
Authors: Smith K. L. , Ruhl H. A. , Bett B. J. , Billett D. S. M. , Lampitt R. S. , Kaufmann R. S.
Published: November 2009

Climate variation affects surface ocean processes and the production of organic carbon, which ultimately comprises the primary food supply to the deep-sea ecosystems that occupy ≈60% of the Earth's surface. Warming trends in atmospheric and upper ocean temperatures, attributed to anthropogenic influence, have occurred over the past four decades. Changes in upper ocean temperature influence stratification and can affect the availability of nutrients for phytoplankton production. Global warming has been predicted to intensify stratification and reduce vertical mixing. Research also suggests that such reduced mixing will enhance variability in primary production and carbon export flux to the deep sea. The dependence of deep-sea communities on surface water production has raised important questions about how climate change will affect carbon cycling and deep-ocean ecosystem function. Recently, unprecedented time-series studies conducted over the past two decades in the North Pacific and the North Atlantic at >4,000-m depth have revealed unexpectedly large changes in deep-ocean ecosystems significantly correlated to climate-driven changes in the surface ocean that can impact the global carbon cycle. Climate-driven variation affects oceanic communities from surface waters to the much-overlooked deep sea and will have impacts on the global carbon cycle. Data from these two widely separated areas of the deep ocean provide compelling evidence that changes in climate can readily influence deep-sea processes. However, the limited geographic coverage of these existing time-series studies stresses the importance of developing a more global effort to monitor deep-sea ecosystems under modern conditions of rapidly changing climate.
Age-related hearing loss in C57BL/6J mice is mediated by Bak-dependent mitochondrial apoptosis
Authors: Someya Shinichi , Xu Jinze , Kondo Kenji , Ding Dalian , Salvi Richard J. , Yamasoba Tatsuya , Rabinovitch Peter S. , Weindruch Richard , Leeuwenburgh Christiaan , Tanokura Masaru , Prolla Tomas A.
Published: November 2009

Age-related hearing loss (AHL), known as presbycusis, is a universal feature of mammalian aging and is the most common sensory disorder in the elderly population. The molecular mechanisms underlying AHL are unknown, and currently there is no treatment for the disorder. Here we report that C57BL/6J mice with a deletion of the mitochondrial pro-apoptotic gene
Bak
exhibit reduced age-related apoptotic cell death of spiral ganglion neurons and hair cells in the cochlea, and prevention of AHL. Oxidative stress induces
Bak
expression in primary cochlear cells, and Bak deficiency prevents apoptotic cell death. Furthermore, a mitochondrially targeted catalase transgene suppresses
Bak
expression in the cochlea, reduces cochlear cell death, and prevents AHL. Oral supplementation with the mitochondrial antioxidants α-lipoic acid and coenzyme Q
10
also suppresses
Bak
expression in the cochlea, reduces cochlear cell death, and prevents AHL. Thus, induction of a Bak-dependent mitochondrial apoptosis program in response to oxidative stress is a key mechanism of AHL in C57BL/6J mice.
CRF system recruitment mediates dark side of compulsive eating
Authors: Cottone Pietro , Sabino Valentina , Roberto Marisa , Bajo Michal , Pockros Lara , Frihauf Jennifer B. , Fekete Eva M. , Steardo Luca , Rice Kenner C. , Grigoriadis Dimitri E. , Conti Bruno , Koob George F. , Zorrilla Eric P.
Published: November 2009

Dieting to control body weight involves cycles of deprivation from palatable food that can promote compulsive eating. The present study shows that rats withdrawn from intermittent access to palatable food exhibit overeating of palatable food upon renewed access and an affective withdrawal-like state characterized by corticotropin-releasing factor-1 (CRF
1
) receptor antagonist-reversible behaviors, including hypophagia, motivational deficits to obtain less palatable food, and anxiogenic-like behavior. Withdrawal was accompanied by increased CRF expression and CRF
1
electrophysiological responsiveness in the central nucleus of the amygdala. We propose that recruitment of anti-reward extrahypothalamic CRF-CRF
1
systems during withdrawal from palatable food, analogous to abstinence from abused drugs, may promote compulsive selection of palatable food, undereating of healthier alternatives, and a negative emotional state when intake of palatable food is prevented.
Crystal structure of NL63 respiratory coronavirus receptor-binding domain complexed with its human receptor
Authors: Wu Kailang , Li Weikai , Peng Guiqing , Li Fang
Published: November 2009

NL63 coronavirus (NL63-CoV), a prevalent human respiratory virus, is the only group I coronavirus known to use angiotensin-converting enzyme 2 (ACE2) as its receptor. Incidentally, ACE2 is also used by group II SARS coronavirus (SARS-CoV). We investigated how different groups of coronaviruses recognize the same receptor, whereas homologous group I coronaviruses recognize different receptors. We determined the crystal structure of NL63-CoV spike protein receptor-binding domain (RBD) complexed with human ACE2. NL63-CoV RBD has a novel β-sandwich core structure consisting of 2 layers of β-sheets, presenting 3 discontinuous receptor-binding motifs (RBMs) to bind ACE2. NL63-CoV and SARS-CoV have no structural homology in RBD cores or RBMs; yet the 2 viruses recognize common ACE2 regions, largely because of a “virus-binding hotspot” on ACE2. Among group I coronaviruses, RBD cores are conserved but RBMs are variable, explaining how these viruses recognize different receptors. These results provide a structural basis for understanding viral evolution and virus–receptor interactions.
Cohesinopathy mutations disrupt the subnuclear organization of chromatin
Authors: Gard Scarlett , Light William , Xiong Bo , Bose Tania , McNairn Adrian J. , Harris Bethany , Fleharty Brian , Seidel Chris , Brickner Jason H. , Gerton Jennifer L.
Published: November 2009

In Saccharomyces cerevisiae, chromatin is spatially organized within the nucleus with centromeres clustering near the spindle pole body, telomeres clustering into foci at the nuclear periphery, ribosomal DNA repeats localizing within a single nucleolus, and transfer RNA (tRNA) genes present in an adjacent cluster. Furthermore, certain genes relocalize from the nuclear interior to the periphery upon transcriptional activation. The molecular mechanisms responsible for the organization of the genome are not well understood. We find that evolutionarily conserved proteins in the cohesin network play an important role in the subnuclear organization of chromatin. Mutations that cause human cohesinopathies had little effect on chromosome cohesion, centromere clustering, or viability when expressed in yeast. However, two mutations in particular lead to defects in (a) GAL2 transcription and recruitment to the nuclear periphery, (b) condensation of mitotic chromosomes, (c) nucleolar morphology, and (d) tRNA gene–mediated silencing and clustering of tRNA genes. We propose that the cohesin network affects gene regulation by facilitating the subnuclear organization of chromatin.
A dual function for Pex3p in peroxisome formation and inheritance
Authors: Munck Joanne M. , Motley Alison M. , Nuttall James M. , Hettema Ewald H.
Published: November 2009

Saccharomyces cerevisiae Pex3p has been shown to act at the ER during de novo peroxisome formation. However, its steady state is at the peroxisomal membrane, where its role is debated. Here we show that Pex3p has a dual function: one in peroxisome formation and one in peroxisome segregation. We show that the peroxisome retention factor Inp1p interacts physically with Pex3p in vitro and in vivo, and split-GFP analysis shows that the site of interaction is the peroxisomal membrane. Furthermore, we have generated PEX3 alleles that support peroxisome formation but fail to support recruitment of Inp1p to peroxisomes, and as a consequence are affected in peroxisome segregation. We conclude that Pex3p functions as an anchor for Inp1p at the peroxisomal membrane, and that this function is independent of its role at the ER in peroxisome biogenesis.
Dependence of nucleotide substitutions on Ung2, Msh2, and PCNA-Ub during somatic hypermutation
Authors: Krijger Peter H.L. , Langerak Petra , van den Berk Paul C.M. , Jacobs Heinz
Published: November 2009

During somatic hypermutation (SHM), B cells introduce mutations into their immunoglobulin genes to generate high affinity antibodies. Current models suggest a separation in the generation of G/C transversions by the Ung2-dependent pathway and the generation of A/T mutations by the Msh2/ubiquitinated proliferating cell nuclear antigen (PCNA-Ub)–dependent pathway. It is currently unknown whether these pathways compete to initiate mutagenesis and whether PCNA-Ub functions downstream of Ung2. Furthermore, these models do not explain why mice lacking Msh2 have a more than twofold reduction in the total mutation frequency. Our data indicate that PCNA-Ub is required for A/T mutagenesis downstream of both Msh2 and Ung2. Furthermore, we provide evidence that both pathways are noncompetitive to initiate mutagenesis and even collaborate to generate half of all G/C transversions. These findings significantly add to our understanding of SHM and necessitate an update of present SHM models.
William Reginald Stephen Garton. 7 March 1912—28 August 2002
Authors: Connerade Jean-Patrick
Published: November 2009

The career of William Reginald Stephen Garton, who died on 28 August 2002, aged 90 years, spanned a long and fascinating period in the history of physics, which saw the birth of quantum mechanics and the confirmation of the theory of relativity.
Host plant trichomes and the advantage of being big: progeny size variation of the pipevine swallowtail
Authors: FORDYCE JAMES A. , DIMARCO ROMINA D. , BLANKENSHIP BONNY A. , NICE CHRIS C.
Published: November 2009

1. Plants possess numerous traits that confer resistance against insect herbivores, and herbivores, in turn, can evolve traits to ameliorate the effectiveness of these traits. The pipevine swallowtail, Battus philenor, is an extreme specialist on plants in the genus Aristolochia. The only host plant available to the California population of B. philenor is A. californica. Aristolochia californica is distinct from most other B. philenor host plants in that it is pubescent.

2. The progeny of B. philenor are larger in California compared with populations examined in Texas. Size differences persist throughout larval development.

3. Regardless of maternal host plant, population differences in progeny size persist, and crosses between California (large progeny) and Texas (small progeny) B. philenor populations resulted in offspring producing intermediate sized progeny, indicating a heritable component to progeny size variation.

4. California neonate caterpillars more easily overcame the trichomes of A. californica compared with Texas neonates. When trichomes were removed from A. californica, time to feeding establishment was reduced for caterpillars from both populations. Texas caterpillars established feeding sites on A. californica with trichomes removed, in the same time required to establish feeding on their non‐pubescent host plant, A. erecta.

5. This study shows that plant trichomes might impose selection pressure on progeny size.
The prevalence of and the related factors for urinary and fecal incontinence among older residing in nursing homes
Authors: Aslan Ergul , Beji Nezihe K , Erkan Habibe A , Yalcin Onay , Gungor Funda
Published: November 2009

Aims and objectives.  To determine the prevalence of urinary incontinence and fecal incontinence among older people residing in nursing homes in Istanbul.

Background.  Urinary incontinence (UI) is a multifactorial condition associated with age‐related changes and disorders of the genitourinary system and systemic problems affecting normal micturition. The impact of UI and fecal incontinence (FI) on older people living in nursing homes is more significant than those living in the community.

Design.  Cross‐sectional study.

Methods.  This study was performed with 1110 older people who were 60 years and older residing in five government rest homes on the European side of Istanbul in Turkey. An interview was conducted with the residents that had sufficient cognitive function and agreed to participate. Demographic findings and complaints about incontinence were analyzed using a special questionnaire.

Results.  The total number of older people who participated was 694; 56·5% females and 43·5% males; 43·4% of females and 20·9% of males. Urge incontinence was common in both groups. FI was more common among females (14%, males 6%) and the mean duration of symptoms was longer. The related factors for UI among older females revealed that history of an episiotomy, frequency, urgency, fecal incontinence and functional incapacity among males; whereas history of stroke and pulmonary disorders were independent variables that increased the incidence of frequency, recurrent urinary tract infections and fecal incontinence. The related factors for fecal incontinence among older females included history of stroke and functional status. Diabetes mellitus requiring medical treatment, frequency, functional incapacity and urinary incontinence were significant related factors for fecal incontinence among males.

Conclusions.  According to similar studies, the urinary and fecal incontinence rates in nursing home residents were lower compared to the other countries. Incontinence was more common among females according to males. Understanding related factors of incontinence are important for providing care and counseling in nursing homes.

Relevance to clinical practice.  Nurses can provide appropriate information and support at each step in the protecting, screening, diagnosis and treatment process so that elders’ incontinence is minimized.
Factors influencing oncology nurses’ approaches to accommodating cultural needs in palliative care
Authors: Huang Ya‐Ling , Yates Patsy , Prior Deborah
Published: November 2009

Aims and objectives.  The purpose of this study is to explore the social construction of cultural issues in palliative care amongst oncology nurses.

Background.  Australia is a nation composed of people from different cultural origins with diverse linguistic, spiritual, religious and social backgrounds. The challenge of working with an increasingly culturally diverse population is a common theme expressed by many healthcare professionals from a variety of countries.

Design.  Grounded theory was used to investigate the processes by which nurses provide nursing care to cancer patients from diverse cultural backgrounds.

Methods.  Semi‐structured interviews with seven Australian oncology nurses provided the data for the study; the data was analysed using grounded theory data analysis techniques.

Results.  The core category emerging from the study was that of accommodating cultural needs. This paper focuses on describing the series of subcategories that were identified as factors which could influence the process by which nurses would accommodate cultural needs. These factors included nurses’ views and understandings of culture and cultural mores, their philosophy of cultural care, nurses’ previous experiences with people from other cultures and organisational approaches to culture and cultural care.

Conclusions.  This study demonstrated that previous experiences with people from other cultures and organisational approaches to culture and cultural care often influenced nurses’ views and understandings of culture and cultural mores and their beliefs, attitudes and behaviours in providing cultural care.

Relevance to clinical practice.  It is imperative to appreciate how nurses’ experiences with people from other cultures can be recognised and built upon or, if necessary, challenged. Furthermore, nurses’ cultural competence and experiences with people from other cultures need to be further investigated in clinical practice.