bluuebunny/crossref_metadata_2025 huggingface dataset:
Extended Algorithm for Simulation of Light Transport in Single Crystal Scintillation Detectors for S(T)EM
Authors: Schauer Petr
Published: October 2007

The new extended Monte Carlo (MC) simulation method for photon transport in S(T)EM back scattered electron (BSE) scintillation detection systems of various shapes is presented in this paper. The method makes use of the random generation of photon emission from a scintillator luminescent centre and describes the trajectory of photons and the efficiency of their transport toward the photocathode of the photomultiplier tube. The paper explains a new algorithm for determining the position of interaction of the photon with the surface of the single crystal scintillator or of the light guide with nearly arbitrary shapes. Some examples of the utilization of the simulation method are also included, and conclusions for very simple edge‐guided signal (EGS) scintillation detection systems made. The computer optimized design of the BSE scintillation detector for the S 4000 Hitachi SEM was chosen to demonstrate the capability of this MC simulation method. SCANNING 29: 249–253, 2007. © 2007 Wiley Periodicals, Inc.
Structural BIM: discussion, case studies and latest developments
Authors: Robinson Clive
Published: October 2007

This paper discusses the current state of building information modelling (BIM) from the structural point of view, incorporating the migration from 2D to 3D solutions. Open interfaces are also considered and how they provide access to BIM information away from the specialist modelling solutions to more conventional software tools, allowing closer design team collaboration. Two case studies are also highlighted to identify the benefits obtained from the structural BIM solution. Copyright © 2007 John Wiley & Sons, Ltd.
Vascular endothelial growth factor restores delayed tumor progression in tumors depleted of macrophages
Authors: Lin Elaine Y. , Li Jiu-feng , Bricard Gabriel , Wang Weigang , Deng Yan , Sellers Rani , Porcelli Steven A. , Pollard Jeffrey W.
Published: October 2007

Genetic depletion of macrophages in Polyoma Middle T oncoprotein (PyMT)‐induced mammary tumors in mice delayed the angiogenic switch and the progression to malignancy. To determine whether vascular endothelial growth factor A (VEGF‐A) produced by tumor‐associated macrophages regulated the onset of the angiogenic switch, a genetic approach was used to restore expression of VEGF‐A into tumors at the benign stages. This stimulated formation of a high‐density vessel network and in macrophage‐depleted mice, was followed by accelerated tumor progression. The expression of VEGF‐A led to a massive infiltration into the tumor of leukocytes that were mostly macrophages. This study suggests that macrophage‐produced VEGF regulates malignant progression through stimulating tumor angiogenesis, leukocytic infiltration and tumor cell invasion.
From the new editors
Authors: Bolton Kingsley , Graddol David , Masthrie Raj
Published: October 2007

WE FACE the task of editing ET with a mixture of trepidation and excitement. Trepidation because our editorial efforts will follow those of Tom McArthur who has been editor of English Today since its inception, and who has made such an immense contribution to scholarship in this field. Indeed, it is no small measure of Tom's stature and capabilities that it has been decided at least three new editors are required to take his place. We have large shoes to fill.
Tarzan of the Russians
Authors: Blaisdell Bob
Published: October 2007

Life among the language bugs. Further tales from New York City.
Kettles of fish: or, does unilateral idiomaticity exist?
Authors: Prodromou Luke
Published: October 2007

Some reflections on the nature of ELF. The focus in this article is what scholars of English as a Lingua Franca (ELF) have referred to as ‘unilateral idiomaticity’ (UI): the use by speakers and writers of idiomatic language which is not understood by the other participants in the interaction. The writer will attempt to identify actual occurrences of UI, drawing on both corpus evidence and an email survey of fifty L1 and L2 ELF-users and will also draw some implications for what we mean by ‘competence’ in lingua franca contexts.
Catchwords as markers of change in China
Authors: Hou Jinxiang
Published: October 2007

A CATCHWORD is a lexical item or phrase, whether created within a particular language or adopted from foreign languages through translation or transliteration or a combination of the two. In Chinese discourse, catchwords spread rapidly within a particular group of people at a particular time and in a particular context (cf. Gu Wei, 2004): a definition from work undertaken at the Institute of Applied Linguistics (founded in 2002 at the Beijing Language and Culture University). The topic is the subject of a treatise, ‘The longitudinal study of catchwords in newspapers’ and is one of the items on the agenda of the Tenth Five-Year Plan, for consideration by the Chinese Language and Characters Committee. Zhang Pu (2003), a professor of language information processing at Beijing Language and Culture University has argued that ‘[a] catchword is not only a lexical phenomenon, but also indicates people's values from a cultural psychology point of view, as well as reflecting social reality’.
An endless coded stream
Authors: Martin Assunta
Published: October 2007

A brief look at the debate between sociolinguists and linguists with some examples of euphemisms that have surfaced into common usage offers revealing insights reflecting contemporary social perceptions. Sociolinguists who investigate the role and function of language are not so much concerned with the way language utterances are generated and constructed as with the ways that language is used in society as a means to communicate. Traditionally, linguists steered clear of the murky waters of social relevance and social context in use, believing that it is a study that cannot yield predictions of future usage, be measured objectively, or tested for accuracy.
Outcrop‐scale physical properties of Burns Formation at Meridiani Planum, Mars
Authors: Nahm Amanda L. , Schultz Richard A.
Published: October 2007

A rock mass rating (RMR) analysis was performed on an outcrop of Burns Formation at Meridiani Planum, Mars. RMR values were calculated for the present dry conditions (RMR = 63) and past wet conditions (RMR = 52). For present‐day dry conditions, the rock mass has an in situ modulus of deformation (E*) of 21.1 GPa, cohesive strength (C*0) of 4.64 MPa, and tensile strength (T*0) of −0.24 MPa. These values were reduced by at most ∼50% during previous water‐saturated conditions. The critical grain crushing pressure (P*) for dry conditions is 19.5 GPa, with an uncertainty of about an order of magnitude. Analysis of the rover observations indicates that the physical properties of Burns Formation are in the range of analogous terrestrial porous rock masses such as sandstone and shale.
Jupiter: A fundamentally different magnetospheric interaction with the solar wind
Authors: McComas D. J. , Bagenal F.
Published: October 2007

Magnetic reconnection between the solar wind and Earth's magnetic field creates an “open” magnetosphere with erosion of magnetic flux from the dayside and return on the nightside. At Jupiter, the large source of plasma from Io and fast rotation rate create a magnetosphere whose dynamics is dominated by internal processes. This, along with its sheer physical size, makes the nightside return of flux difficult, if not impossible. However, because magnetic reconnection still occurs on Jupiter's dayside magnetopause, it has been generally assumed that Jupiter's magnetosphere must be similarly open. Here we show how additional reconnection between the IMF and open magnetospheric flux back near flanks can re‐close this open flux without having to invoke reconnection in the Jovian magnetotail. Our reconnection cycle solves the problem of closing and returning open magnetic flux in a large, internally dominated magnetosphere that constantly sheds large amounts of plasma down its magnetotail.
HiRISE observations of slope streaks on Mars
Authors: Chuang Frank C. , Beyer Ross A. , McEwen Alfred S. , Thomson Bradley J.
Published: October 2007

Images from the High Resolution Imaging Science Experiment have revealed new details on the morphologic and topographic characteristics of slope streaks on Mars. Over 1500 HiRISE images were analyzed with 78 unique image sites having slope streaks. Images with low sun illumination reveal that dark slope streaks have topographic relief where streaked surfaces are lower than their surroundings. Slope streaks often initiate below localized features such as rock outcrops, individual boulders, and impact craters. They are also abundant in great numbers within the blast zones of small young impact craters 10–50 m in diameter. These observations suggest that slope streaks can be triggered by localized disturbances such as rockfalls and impact blasts. Seismic activity from external (e.g., impacts) or internal forces could also trigger slope streaks. The topographic relief and triggering mechanisms of slope streaks seem to best fit models that involve dry dust avalanches. Martian slope streaks and meters‐thick avalanche scars are part of a continuum of active mass‐wasting features at meter to sub‐meter scales.
Strength and deformability of light‐toned layered deposits observed by MER Opportunity: Eagle to Erebus craters, Mars
Authors: Okubo Chris H.
Published: October 2007

Quantifying host rock deformation is vital to understanding the geologic evolution and productivity of subsurface fluid reservoirs. In support of on‐going characterization of fracture controlled fluid flow through the light‐toned layered deposits on Mars, key parameters of strength and deformability are derived from Microscopic Imager and Rock Abrasion Tool data collected by the Mars Exploration Rover Opportunity in Meridiani Planum. Analysis of 21 targets of light‐toned layered deposits yields a median apparent porosity of 0.25. Additional physical parameters for each target are derived from these porosity measurements. The median value of unconfined compressive strength is 11.23 MPa, Young's modulus is 1.86 GPa, and the brittle‐ductile transition pressure is 8.77 MPa.
Studies on the production of O2(a1Δg, υ = 0) and O2(b1Σg+, υ = 0) from collisional removal of O2(A3Σu+, υ′ = 6–10)
Authors: Pejaković Dušan A. , Copeland Richard A. , Cosby Philip C. , Slanger Tom G.
Published: October 2007

Production of two metastable O2 species, O2(a1Δg, υ = 0) and O2(b1Σg+, υ = 0), from collisional removal of O2(A3Σu+) by O2 and N2 is investigated at a temperature of 240 K. A state‐selective two‐laser technique is used, in which the output of the first laser excites ground‐state O2 molecules to a specific vibrational level (6 ≤ υ′ ≤ 10) in the A3Σu+ state, and the output of the second laser subsequently probes the O2(a1Δg, υ = 0) and O2(b1Σg+, υ = 0) populations by resonance‐enhanced multiphoton ionization via the intermediate d1Πg Rydberg state. For the relatively short timescales of our experiment (∼10−4 Torr·s), we find that the O2(a1Δg, υ = 0) quantum yield from collisional removal of O2(A3Σu+, υ′) by O2 is approximately constant for υ′ = 7–9, and decreases by 30–40% for υ′ = 6 and 10. The O2(b1Σg+, υ = 0) yield is nearly constant for υ′ = 8–10, and decreases by about 50% for υ′ = 6 and 7. The eventual O2(a1Δg, υ = 0) and O2(b1Σg+, υ = 0) yields from O2(A3Σu+, υ′ = 8) measured in synthetic air are nearly equal to those measured in pure O2, suggesting that N2 collider does not significantly affect the relaxation pathways leading to the production of the two metastable species. However, at short experimental times the buildup of the O2(a1Δg, υ = 0) population is considerably slower in synthetic air than in O2.
Simulation of entrainment and transport of dust particles within North America in April 2001 (“Red Dust Episode”)
Authors: Park S. H. , Gong S. L. , Zhao T. L. , Vet R. J. , Bouchet V. S. , Gong W. , Makar P. A. , Moran M. D. , Stroud C. , Zhang J.
Published: October 2007

A size‐resolved, multicomponent, regional‐scale particulate‐matter (PM) model named AURAMS (A Unified Regional Air‐quality Modelling System) has been used to study the entrainment and transport of dust from the southwestern United States and northwestern Mexico to eastern North America during the so‐called “Red Dust Episode” in April, 2001. Two different wind‐blown‐dust emission schemes, the Marticorena‐Bergametti‐Alfaro (MBA) scheme and the Shao scheme, were incorporated into AURAMS to simulate dust generation, and sensitivity analyses for various dust‐emission‐scheme parameters were performed. Comparison of the model results with satellite observations and surface measurements showed that the model simulation reasonably reproduced the temporal and spatial distribution of wind‐blown dust particles during the episode period in the downwind area of Oklahoma but not in the source region. Both dust‐emission schemes captured the main features of the dust transport. The dust‐emission‐scheme parameter most responsible for inaccurate prediction of wind‐blown‐dust emission in the source region in this study appeared to be soil moisture content. The soil grain size distribution and the soil plastic pressure were also shown to be important parameters that should be accurately estimated for better model performance. For further validation and reliable use of wind‐blown‐dust emission schemes, accurate field and remote sensing measurements of those parameters are imperative. The unusually fast transport of dust during the episode appeared to be due to vigorous vertical mixing and uplift of emitted dust. Appropriate parameterization of additional vertical mixing by sub‐grid‐scale convection may help to better predict the long‐range transport of dust storms.
A continuous time random walk approach to the stream transport of solutes
Authors: Boano F. , Packman A. I. , Cortis A. , Revelli R. , Ridolfi L.
Published: October 2007

The transport of solutes in rivers is influenced by the exchange of water between the river and the underlying hyporheic zone. The residence times of solutes in the hyporheic zone are typically much longer than traveltimes in the stream, resulting in a significant delay in the downstream propagation of solutes. A new model for this process is proposed here on the basis of the continuous time random walk (CTRW) approach. The CTRW is a generalization of the classic random walk that can include arbitrary distributions of waiting times, and it is particularly suited to deal with the long residence times arising from hyporheic exchange. Inclusion of suitable hyporheic residence time distributions in the CTRW leads to a generalized advection‐dispersion equation for in‐stream concentration breakthrough curves that includes the effects of specific hyporheic exchange processes. Here examples are presented for advective hyporheic exchange resulting from regular and irregular series of bedforms. A second major advantage of the CTRW approach is that the combined effects of different processes affecting overall downstream transport can be incorporated in the model by convolving separate waiting time distributions for each relevant process. The utility of this approach is illustrated by analyzing the effects of local‐scale sediment heterogeneity on bedform‐induced hyporheic exchange. The ability to handle arbitrarily wide residence time distributions and the ability to assess the combined effects of multiple transport processes makes the CTRW model framework very useful for the study of solute transport problems in rivers. The model presented here can be easily extended to represent different types of surface‐subsurface exchange processes and the transport of both conservative and nonconservative substances in rivers.
Side effect profile prediction - Tackling Big Pharma's worst nightmare at an early stage
Authors: Scheiber Josef
Published: October 2007

This talk presents a method that predicts adverse side effects for molecules based on the chemical structure only. Also, targets for the compounds are predicted. Therefore it becomes possible to link a certain side effect to the interaction with a certain target through molecular space. Examples are given in the talk.
Estimation of DNA Sequence Context-dependent Mutation Rates Using Primate Genomic Sequences: Application to Estimation of Selection Bias in Protein (Human TP53) Evolution
Authors: Zhang Wei
Published: October 2007

Understanding of the mechanism of DNA mutation process is critical for studying the functional consequences of genetic variation in clinical medicine (eg. drug response) as well as other complex traits (eg. gene expression and cause of common diseases). During the last several decades, many probabilistic models of DNA nucleotide substitution have been proposed for studying this process. A common feature of these mutation models is that they assume the nucleotides evolve independently at each site. In other words, they are sequence context-independent models. However, based on various biochemical studies, it is now recognized that the DNA mutation process resulting in substitutions in both coding and non-coding regions may depend on sequence context. We proposed here a more realistic sequence context-dependent mutation model, which could contribute to the better understanding of the DNA mutation spectrum in genomes.We also showed its application to protein evolution by separating the mutation bias and selection bias in amino acid substitutions.
Wireless Technologies at Agriculture ITO
Authors: Scornavacca Eusebio
Published: October 2007

This teaching case portrays the issues surrounding the adoption of an emerging technology (mobile internet) by Agriculture ITO – an industry training organization in New Zealand. The widespread geographical nature of the organization creates a unique business scenario that can be of great value to instructors teaching IS management, technology adoption and mobility.
Chaos generated pinch effect in toroidal confinement devices
Authors: Spizzo G. , White R. B. , Cappello S.
Published: October 2007

Particle transport in a toroidal plasma confinement device is shown to be nondiffusive when magnetic chaos is present. A phenomenological fit to density profiles gives a diffusion constant and also a pinch velocity directed up the density gradient. We show that the combination of diffusion and pinch is actually an expression of the nonlocal, subdiffusive nature of the transport. The effect is illustrated by numerical modelling of the magnetic structure and associated particle transport in conditions relevant for the reversed-field pinch experiment at the Consorzio RFX, Padova, Italy [G. Rostagni, Fusion Eng. Des. 25, 301 (1995)]. The relevance of this result is quite general, and could be applied also to other systems with chaos induced particle transport, such as electron transport in the tokamak.
Sequential quadratic programming method for determining the minimum energy path
Authors: Burger Steven K. , Yang Weitao
Published: October 2007

A new method, referred to as the sequential quadratic programming method, is presented for determining minimum energy paths. The method is based on minimizing the points representing the path in the subspace perpendicular to the tangent of the path while using a penalty term to prevent kinks from forming. Rather than taking one full step, the minimization is divided into a number of sequential steps on an approximate quadratic surface. The resulting method can efficiently determine the reaction mechanism, from which transition state can be easily identified and refined with other methods. To improve the resolution of the path close to the transition state, points are clustered close to this region with a reparametrization scheme. The usefulness of the algorithm is demonstrated for the Müller-Brown potential, amide hydrolysis, and an 89 atom cluster taken from the active site of 4-oxalocrotonate tautomerase for the reaction which catalyzes 2-oxo-4-hexenedioate to the intermediate 2-hydroxy-2,4-hexadienedioate.
Direct correlation function for the square-well potential
Authors: Tang Yiping
Published: October 2007

An analytical expression of direct correlation function (DCF) for the square-well potential is developed. The development is based on the first-order mean spherical approximation and its extension to the functionality of the existing radial distribution function. The developed DCF is a combination of a special polynomial function introduced in this work. The combination is piecewise in four regions [0,λ−1], [λ−1,2−λ], [2−λ,1], and [1,λ] for λ<1.5 or [0,2−λ], [2−λ,λ−1], [λ−1,1], and [1,λ] for λ>1.5. In addition, the DCF is continuous to second-order inside hard core and discontinuous at r=1 and r=λ outside it. The behavior of DCF is analyzed by some detail calculations.
Homogeneous nucleation and growth of melt in copper
Authors: Zheng Lianqing , An Qi , Xie Yun , Sun Zehui , Luo Sheng-Nian
Published: October 2007

Molecular dynamics simulations are conducted to investigate homogeneous nucleation and growth of melt in copper described by an embedded-atom method (EAM) potential. The accuracy of this EAM potential for melting is validated by the equilibrium melting point obtained with the solid-liquid coexistence method and the superheating-supercooling hysteresis method. We characterize the atomistic melting process by following the temperature and time evolution of liquid atoms. The nucleation behavior at the extreme superheating is analyzed with the mean-first-passage-time (MFPT) method, which yields the critical size, steady-state nucleation rate, and the Zeldovich factor. The value of the steady-state nucleation rate obtained from the MFPT method is consistent with the result from direct simulations. The size distribution of subcritical nuclei appears to follow a power law similar to three-dimensional percolation. The diffuse solid-liquid interface has a sigmoidal profile with a 10%−90% width of about 12 Å near the critical nucleation. The critical size obtained from our simulations is in reasonable agreement with the prediction of classical nucleation theory if the finite interface width is considered. The growth of melt is coupled with nucleation and can be described qualitatively with the Johnson-Meh-Avrami law. System sizes of 103−106 atoms are explored, and negligible size dependence is found for bulk properties and for the critical nucleation.
Ionic melts with waterlike anomalies: Thermodynamic properties of liquid BeF2
Authors: Agarwal Manish , Sharma Ruchi , Chakravarty Charusita
Published: October 2007

Thermodynamic properties of liquid beryllium difluoride (BeF2) are studied using canonical ensemble molecular dynamics simulations of the transferable rigid ion model potential. The negative slope of the locus of points of maximum density in the temperature-pressure plane is mapped out. The excess entropy, computed within the pair correlation approximation, is found to show an anomalous increase with isothermal compression at low temperatures which will lead to diffusional as well as structural anomalies resembling those in water. The anomalous behavior of the entropy is largely connected with the behavior of the Be–F pair correlation function. The internal energy shows a T3∕5 temperature dependence. The pair correlation entropy shows a T−2∕5 temperature dependence only at high densities and temperatures. The correlation plots between internal energy and the pair correlation entropy for isothermal compression show the characteristic features expected of network-forming liquids with waterlike anomalies. The tagged particle potential energy distributions are shown to have a multimodal form at low temperatures and densities similar to those seen in other liquids with three-dimensional tetrahedral networks, such as water and silica.
Communication through plasma sheaths
Authors: Korotkevich A. O. , Newell A. C. , Zakharov V. E.
Published: October 2007

We wish to transmit messages to and from a hypersonic vehicle around which a plasma sheath has formed. For long distance transmission, the signal carrying these messages must be necessarily low frequency, typically 2 GHz, to which the plasma sheath is opaque. The idea is to use the plasma properties to make the plasma sheath appear transparent.
Kilohertz laser ablation for doping helium nanodroplets
Authors: Mudrich M. , Forkl B. , Müller S. , Dvorak M. , Bünermann O. , Stienkemeier F.
Published: October 2007

A new setup for doping helium nanodroplets by means of laser ablation at kilohertz repetition rate is presented. The doping process is characterized and two distinct regimes of laser ablation are identified. The setup is shown to be efficient and stable enough to be used for spectroscopy, as demonstrated on beam depletion spectra of lithium atoms attached to helium nanodroplets. For the first time, helium droplets are doped with high temperature refractory materials such as titanium and tantalum. Doping with the nonvolatile DNA basis guanine is found to be efficient and a number of oligomers are detected.
Backscattering position detection for photonic force microscopy
Authors: Volpe Giovanni , Kozyreff Gregory , Petrov Dmitri
Published: October 2007

An optically trapped particle is an extremely sensitive probe for the measurement of pico- and femto-Newton forces between the particle and its environment in microscopic systems (photonic force microscopy). A typical setup comprises an optical trap, which holds the probe, and a position sensing system, which uses the scattering of a beam illuminating the probe. Usually the position is accurately determined by measuring the deflection of the forward-scattered light transmitted through the probe. However, geometrical constraints may prevent access to this side of the trap, forcing one to make use of the backscattered light instead. A theory is presented together with numerical results that describes the use of the backscattered light for position detection. With a Mie–Debye approach, we compute the total (incident plus scattered) field and follow its evolution as it is collected by the condenser lenses and projected onto the position detectors and the responses of position sensitive detectors and quadrant photodetectors to the displacement of the probe in the optical trap, both in forward and backward configurations. We find out that in the case of backward detection, for both types of detectors the displacement sensitivity can change sign as a function of the probe size and is null for some critical sizes. In addition, we study the influence of the numerical aperture of the detection system, polarization, and the cross talk between position measurements in orthogonal directions. We finally discuss how these features should be taken into account in experimental designs.
Polarity-sensitive switching induced by the electric field in a self-assembled nematic system from two different achiral species of molecules
Authors: Lee Ji-Hoon , Jang Chi-Woong , Lim Tong-Kun
Published: October 2007

A polarity-sensitive switching behavior was observed in the nematic phase of a system of unit blocks self-assembled from an achiral rod-shaped liquid crystal (LC) and an achiral tripod-shaped dopant. This unit block has a shape of a tripod with extended legs and showed a spontaneous polarization under the applied electric field. Although the polarity-sensitive switching in the achiral LCs is intrinsically impossible, our system of the tripod-shaped unit blocks made with the linear-shaped achiral 8CB bound to the stretched branches of the tripod-shaped achiral dopant by the steric interaction or by the hydrogen bonding showed the polarity-sensitive switching. At zero applied field state, the unit blocks were aligned helically to compensate the macroscopic polarization value. As the field was applied, the helical structure was unwound and the optic axis of the sample rotated clockwise or counterclockwise depending on the sign of the applied field. The threshold field to show the polarity-sensitive switching was lower in the sterically assembled sample (0.1V∕μm) than in the hydrogen-bonded one (1.3V∕μm) and the field response time was much faster in the former case. In addition, the response time of the sterically assembled sample was linearly proportional to the strength of the electric field in the strong field regime, but the one of the hydrogen-bonded sample was saturated in the strong field regime.
Light localization at randomly textured surfaces for solar-cell applications
Authors: Rockstuhl Carsten , Lederer Falk , Bittkau Karsten , Carius Reinhard
Published: October 2007

By using a rigorous diffraction theory, the localization of light near textured zinc oxide (ZnO) surfaces is theoretically investigated and compared with experimental data obtained from scanning-near-field-optical microscopy. Although random by nature, these surfaces show well-defined geometrical features, which cause the formation of localized light patterns near the surface. Particularly, photon jets are observed to emerge from conical surface structures. Because these structures are of primary importance for applications in photovoltaics, we analyze the “real” surface topography of textured ZnO used in silicon solar cells. With this work, valuable insight is provided into the mechanism of light coupling through randomly textured interfaces.
A molecular memory device formed by HfO2 encapsulation of redox-active molecules
Authors: Chen Zhong , Lee Bongmook , Sarkar Smita , Gowda Srivardhan , Misra Veena
Published: October 2007

Solid state metal-insulator-molecule-metal (MIMM) devices were fabricated by encapsulating a redox-active molecular layer between a metal substrate and a dielectric thin film of atomic layer deposition (ALD) hafnium dioxide (HfO2). Redox properties of molecules are preserved after atomic layer deposition. The leakage current of devices is greatly improved by incorporating the ALD HfO2 thin layer. Capacitance measurements of these MIMM devices show a large frequency dispersion indicating the charging and discharging of the molecular layer.
Bulk acoustic wave analysis of crystalline plane oriented ZnO films
Authors: Wu Sean , Lin Zhi-Xun , Lee Maw-Shung , Ro Ruyen
Published: October 2007

Bulk acoustic wave (BAW) properties of piezoelectric layer are very important design parameters for film bulk acoustic wave resonator devices. In this research, BAW properties of all crystalline plane oriented sputtered and epitaxial ZnO films were analyzed theoretically. The (002), (004), and (006) oriented ZnO films provided a pure longitudinal mode. The (100), (110), (200), (210), (300), and (220) oriented ZnO films provided a pure fast shear mode. The (101), (102), (103), (112), (201), (202), (104), (203), (211), (114), (212), (105), (204), (213), (302), (205), (106), and (214) oriented ZnO films provided a quasilongitudinal mode and a quasishear mode. Those bulk acoustic wave properties can be used for further device design and application.
Isothermal low-field tuning of exchange bias in epitaxial Fe∕Cr2O3∕Fe
Authors: Sahoo S. , Mukherjee T. , Belashchenko K. D. , Binek Ch.
Published: October 2007

Moderate dc magnetic fields of less than 1T allow tuning the exchange bias in an epitaxially grown Fe 10nm∕Cr2O3 2.7nm∕Fe 10nm trilayer between negative and positive bias fields. Remarkably, this tunable exchange bias is observed at least up to 395K which exceeds the Néel temperature of bulk Cr2O3 (307K). The presence of spontaneous exchange bias and the absence of training effects at room temperature suggest the existence of stable interface moments independent of antiferromagnetic long range order in Cr2O3. Furthermore, the coercivity remains constant, independent of the exchange bias field. In contrast, large training associated with nonequilibrium spin configurations of antiferromagnetically ordered Cr2O3 appears below 50K.
Plasmonic quantum cascade laser antenna
Authors: Yu Nanfang , Cubukcu Ertugrul , Diehl Laurent , Belkin Mikhail A. , Crozier Kenneth B. , Capasso Federico , Bour David , Corzine Scott , Höfler Gloria
Published: October 2007

We report a plasmonic quantum cascade laser antenna that confines coherent midinfrared radiation well below the diffraction limit. The antenna was fabricated on the facet of a midinfrared quantum cascade laser and consists of a pair of gold nanorods separated by a gap. The antenna near field was characterized by an apertureless near-field scanning optical microscope; field confinement of about 100 and 70nm, limited by the gap size, was demonstrated at wavelengths of 7.0 and 5.3μm, respectively. This device may find important applications in midinfrared subwavelength chemical and biological imaging and spectroscopy.
FePt nanodot arrays with perpendicular easy axis, large coercivity, and extremely high density
Authors: Kim Chaehyun , Loedding Thomas , Jang Seongjin , Zeng Hao , Li Zhen , Sui Yucheng , Sellmyer David J.
Published: October 2007

Ordered FePt nanodot arrays with extremely high density have been developed by physical vapor deposition using porous alumina templates as evaporation masks. Nanodot diameter of 18nm and periodicity of 25nm have been achieved, resulting in an areal density exceeding 1×1012dots∕in.2. Rapid thermal annealing converts the disordered fcc to L10 phase, resulting in (001)-oriented FePt nanodot arrays with perpendicular anisotropy and large coercivity, without the need of epitaxy. High anisotropy and coercivity, perpendicular easy axis orientation and extremely high density are desirable features for future magnetic data storage media applications.
Uniformly dispersed deposition of colloidal nanoparticles and nanowires by boiling
Authors: Lee Kyumin , Duchamp M. , Kulik G. , Magrez A. , Seo Jin Won , Jeney S. , Kulik A. J. , Forró L. , Sundaram R. S. , Brugger J.
Published: October 2007

Uniformly dispersed deposition of various nanoparticles (gold and silver of 20–50nm) and nanowires (ZnO and VOx) on different surfaces (Si, GaAs, mica, and steel) was obtained by boiling colloid drops on preheated substrates. Our results suggest a deposition mechanism based on the formation of microdrops induced by boiling. Indeed, microdrops produced by an ink-jet printing system resulted in uniformly dispersed deposits when the substrate was heated to high temperatures. We demonstrate that boil-deposited gold nanoparticles could be used for the catalytic growth of ZnO nanowires as well as for the manipulation of individual particles by means of an atomic force microscope.
Stochastic inhibitor release and binding from single-enzyme molecules
Authors: Gorris Hans H. , Rissin David M. , Walt David R.
Published: October 2007

Inhibition kinetics of single-β-galactosidase molecules with the slow-binding inhibitor
d
-galactal have been characterized by segregating individual enzyme molecules in an array of 50,000 ultra small reaction containers and observing substrate turnover changes with fluorescence microscopy. Inhibited and active states of β-galactosidase could be clearly distinguished, and the large array size provided very good statistics. With a pre-steady-state experiment, we demonstrated the stochastic character of inhibitor release, which obeys first-order kinetics. Under steady-state conditions, the quantitative detection of substrate turnover changes over long time periods revealed repeated inhibitor binding and release events, which are accompanied by conformational changes of the enzyme's catalytic site. We proved that the rate constants of inhibitor release and binding derived from stochastic changes in the substrate turnover are consistent with bulk-reaction kinetics.
Discordance between living and death assemblages as evidence for anthropogenic ecological change
Authors: Kidwell Susan M.
Published: October 2007

Mismatches between the composition of a time-averaged death assemblage (dead remains sieved from the upper mixed-zone of the sedimentary column) and the local living community are typically attributed to natural postmortem processes. However, statistical analysis of 73 molluscan data sets from estuaries and lagoons reveals significantly poorer average “live-dead agreement” in settings of documented anthropogenic eutrophication (AE) than in areas where AE and other human impacts are negligible. Taxonomic similarity of paired live and dead species lists declines steadily among areas as a function of AE severity, and, for data sets comprising only adults, rank-order agreement in species abundance drops where AE is suspected. The observed live-dead differences in composition are consistent with eutrophication (anomalous abundance of seagrass-dwellers and/or scarcity of organic-loving species in the death assemblage), suggesting compositional inertia of death assemblages to recent environmental change. Molluscan data sets from open shelf settings (
n
= 34) also show higher average live-dead discordance in areas of AE. These results indicate that (
i
) live-dead discordance in surficial grab samples provides valuable evidence for strong anthropogenic modification of benthic communities, (
ii
) actualistic estimates of the ecological fidelity of molluscan death assemblages tend to be erroneously pessimistic when conducted in nonpristine settings, and (
iii
) based on their high fidelity in pristine study areas, death assemblages are a promising means of reconstructing otherwise elusive preimpact ecological baselines from sedimentary records.
The relationship of intrapartum and antepartum stillbirth rates to measures of obstetric care in developed and developing countries
Authors: GOLDENBERG ROBERT L. , MCCLURE ELIZABETH M. , BANN CARLA M.
Published: October 2007

Background. The objective of this study was to explore the relationship between intrapartum and antepartum stillbirths and various measures of obstetric care in developing and developed countries. Methods. For 51 countries, we obtained data about intrapartum and antepartum stillbirth rates and obstetric care measures from the World Health Organisation (WHO) and other sources. Using piecewise regression techniques, the relationships between the intrapartum and antepartum stillbirth rates and the various measures of obstetric care were determined. Results. Developed countries had lower total stillbirth rates (6.0 versus 21.3/1,000 births, p = 0.0002) as well as a lower fraction of stillbirths that were intrapartum (0.16 versus 0.31, p = 0.0019). Developed country antepartum stillbirth rates were 5.2 versus 14.0/1,000 in developing countries (p = 0.0002). The highest antepartum stillbirth rates, all in southern Africa and Asia, ranged from 25 to 35/1,000 births. Intrapartum stillbirth rates averaged 0.9/1,000 births for developed countries compared to 7.3/1,000 in developing countries (p = 0.0024), but ranged as high as 20–25/1,000 births for some countries in southern Africa and Asia. The relationship between intrapartum stillbirth and the various measures of care were generally stronger than those for antepartum stillbirth. Over the entire range of values, for each 1% increase in the percentage of women with at least 4 antenatal visits, the intrapartum stillbirth rate decreased by 0.16 per 1,000 births (p<0.0001). As cesarean section rates increased from 0 to 8%, for each 1% increase, there was a decrease of 1.61 intrapartum stillbirths per 1,000 births. There was no relationship between the cesarean section rates and intrapartum stillbirth rates in developed countries. Conclusions. The intrapartum stillbirth rate is more closely related to various measures of obstetric care than the antepartum stillbirth rate. Increases in cesarean section rates up to 8% are associated with significant improvements in intrapartum stillbirth rates.
Poverty, Petroleum & Policy Intervention: Lessons from the Chad-Cameroon Pipeline
Authors: Kojucharov Nikola
Published: October 2007

The ‘resource curse’ – the tendency of resource wealth to impair natural resource exporting countries on various economic and political dimensions – has shown some of its strongest manifestations in Africa's petro-states. For this reason, the World Bank's recent attempt to engineer an accountable and transparent oil economy in one of Africa's poorest and most corrupt countries – Chad – deserves close scrutiny and critical analysis. Although the World Bank has conducted the Chad-Cameroon Pipeline Project with the belief that the ‘resource curse’ can be mitigated through sound economic and fiscal policies, the results thus far suggest that Chad is doomed to repeat an all too familiar fate of economic turmoil and political strife. This article draws on the disappointing realities since Chad's first oil exports, and examines three major factors underlying Chad's unsuccessful conversion of oil revenues into poverty reduction: institutional capacity constraints, socio-political incompatibilities, and subversive interactions with external lenders. Although the majority of critics attribute the project's failures to the World Bank's policy choices and management, this analysis suggests that the project has been hindered more by the external nature of the World Bank's policy intervention than by any particular design flaws. Given the shortcomings of the Bank's intervention, this article considers plausible revisions to the project, and draws policy implications for future development endeavours of this nature.
Existence of renormalized solutions to nonlinear elliptic equations with two lower order terms and measure data
Authors: Guibé Olivier , Mercaldo Anna
Published: October 2007

In this paper we prove the existence of a renormalized solution to a class of nonlinear elliptic problems whose prototype is<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout 1st Row with Label left-parenthesis upper P right-parenthesis EndLabel StartLayout Enlarged left-brace 1st Row 1st Column minus white up pointing triangle u minus d i v left-parenthesis c left-parenthesis x right-parenthesis StartAbsoluteValue u EndAbsoluteValue Superscript gamma Baseline right-parenthesis plus b left-parenthesis x right-parenthesis StartAbsoluteValue nabla u EndAbsoluteValue Superscript lamda Baseline equals mu 2nd Column a m p semicolon in normal upper Omega comma 2nd Row 1st Column u equals 0 2nd Column a m p semicolon in partial-differential normal upper Omega comma EndLayout EndLayout">(P){−△pu−div⁡(c(x)|u|γ)+b(x)|∇u|λ=μamp;in Ω,u=0amp;in ∂Ω,\begin{equation}\tag {P} \begin {cases} - \bigtriangleup _p u -\operatorname {div}(c(x)|u|^{\gamma })+b(x)|\nabla u|^{\lambda } =\mu & \text {in $\Omega $},\\ u=0 & \text {in $\partial \Omega $}, \end{cases} \end{equation}whereΩ\Omegais a bounded open subset ofRN\mathbb {R}^N,N≥2N\geq 2,△p\bigtriangleup _pis the so-calledp−p-Laplace operator,1>p>N1> p> N,μ\muis a Radon measure with bounded variation onΩ\Omega,0≤γ≤p−10\le \gamma \le p-1,0≤λ≤p−10\le \lambda \le p-1, and|c||c|andbbbelong to the Lorentz spacesLNp−1,r(Ω)L^{\frac {N}{p-1},r}(\Omega ),Np−1≤r≤+∞\frac {N}{p-1}\leq r \leq +\infty, andLN,1(Ω)L^{N,1}(\Omega ), respectively. In particular we prove the existence under the assumptions thatγ=λ=p−1\gamma =\lambda =p-1,|c||c|belongs to the Lorentz spaceLNp−1,r(Ω)L^{\frac {N}{p-1},r}(\Omega ),Np−1≤r>+∞\frac {N}{p-1}\leq r>+\infty, and‖c‖LNp−1,r(Ω)\|c\|_{ L^{\frac {N}{p-1},r}(\Omega )}is small enough.
The zeta function of the Laplacian on certain fractals
Authors: Derfel Gregory , Grabner Peter , Vogl Fritz
Published: October 2007

We prove that the zeta function

ζ
Δ

\zeta _\Delta

of the Laplacian

Δ
\Delta

on self-similar fractals with spectral decimation admits a meromorphic continuation to the whole complex plane. We characterise the poles, compute their residues, and give expressions for some special values of the zeta function. Furthermore, we discuss the presence of oscillations in the eigenvalue counting function, thereby answering a question posed by J. Kigami and M. Lapidus for this class of fractals.
Unitary dual of the non-split inner form of 𝑆𝑝(8,𝐹)
Authors: Hanzer Marcela
Published: October 2007

We classify the non-cuspidal part of the unitary dual of the non-quasi-split inner form of

S
p
(
8
,
F
)

Sp(8,F)

, where

F
F

is a non-archimedean field of characteristic zero. We obtain a conjectural description of the discrete

L
L

-packets which contain representations of

S
p
(
4
,
F
)

Sp(4,F)

and its non-split inner form.
The kernels of radical homomorphisms and intersections of prime ideals
Authors: Pham Hung
Published: October 2007

We establish a necessary condition for a commutative Banach algebraAAso that there exists a homomorphismθ\thetafromAAinto another Banach algebra such that the prime radical of the continuity ideal ofθ\thetais not a finite intersection of prime ideals inAA. We prove that the prime radical of the continuity ideal of an epimorphism fromAAonto another Banach algebra (or of a derivation fromAAinto a BanachAA-bimodule) is always a finite intersection of prime ideals. Under an additional cardinality condition (and assuming the Continuum Hypothesis), this necessary condition is proved to be sufficient. En route, we give a general result on norming commutative semiprime algebras; extending the class of algebras known to be normable. We characterize those locally compact metrizable spacesΩ\Omegafor which there exists a homomorphism fromC0(Ω)\mathcal C_0(\Omega )into a radical Banach algebra whose kernel is not a finite intersection of prime ideals.
Some new results in multiplicative and additive Ramsey theory
Authors: Beiglböck Mathias , Bergelson Vitaly , Hindman Neil , Strauss Dona
Published: October 2007

There are several notions of largeness that make sense in any semigroup, and others such as the various kinds of density that make sense in sufficiently well-behaved semigroups including

(

N

,
+
)

(\mathbb {N},+)

and

(

N

,
⋅
)

(\mathbb {N},\cdot )

. It was recently shown that sets in

N

\mathbb {N}

which are multiplicatively large must contain arbitrarily large geoarithmetic progressions, that is, sets of the form

{

r
j

(
a

+

i
d
)

:
i
,
j
∈
{
0
,
1
,
…
,
k
}

}

\big \{r^j(a\!+\!id)\!:i,j\in \{0,1,\dotsc ,k\}\big \}

, as well as sets of the form

{

b
(
a
+
i
d

)
j

:
i
,
j
∈
{
0
,
1
,
…
,
k
}

}

\big \{b(a+id)^j:i,j\in \{0,1,\dotsc ,k\}\big \}

. Consequently, given a finite partition of

N

\mathbb {N}

, one cell must contain such configurations. In the partition case we show that we can get substantially stronger conclusions. We establish some combined additive and multiplicative Ramsey theoretic consequences of known algebraic results in the semigroups

(
β

N

,
+
)

(\beta \mathbb {N},+)

and

(
β

N

,
⋅
)

(\beta \mathbb {N},\cdot )

, derive some new algebraic results, and derive consequences of them involving geoarithmetic progressions. For example, we show that given any finite partition of

N

\mathbb {N}

there must be, for each

k
k

, sets of the form

{

b
(
a
+
i
d

)
j

:
i
,
j
∈
{
0
,
1
,
…
,
k
}

}

\big \{b(a+id)^j:i,j\in \{0,1,\dotsc ,k\}\big \}

together with

d
d

, the arithmetic progression

{

a
+
i
d
:
i
∈
{
0
,
1
,
…
,
k
}

}

\big \{a+id:i\in \{0,1,\dotsc ,k\}\big \}

, and the geometric progression

{

b

d
j

:
j
∈
{
0
,
1
,
…
,
k
}

}

\big \{bd^j:j\in \{0,1,\dotsc ,k\}\big \}

in one cell of the partition. More generally, we show that, if

S
S

is a commutative semigroup and

F

{\mathcal F}

a partition regular family of finite subsets of

S
S

, then for any finite partition of

S
S

and any

k
∈

N

k\in \mathbb {N}

, there exist

b
,
r
∈
S

b,r\in S

and

F
∈

F

F\in {\mathcal F}

such that

r
F
∪
{
b
(
r
x

)
j

:
x
∈
F
,
j
∈
{
0
,
1
,
2
,
…
,
k
}
}

rF\cup \{b(rx)^j:x \in F,j\in \{0,1,2,\ldots ,k\}\}

is contained in a cell of the partition. Also, we show that for certain partition regular families

F

{\mathcal F}

and

G

{\mathcal G}

of subsets of

N

\mathbb {N}

, given any finite partition of

N

\mathbb {N}

some cell contains structures of the form

B
∪
C
∪
B
⋅
C

B \cup C \cup B\cdot C

for some

B
∈

F

,
C
∈

G

B\in {\mathcal F}, C\in {\mathcal G}

.
A characterization of homeomorphic Bernoulli trial measures
Authors: Yingst Andrew
Published: October 2007

We give conditions which, given two Bernoulli trial measures, determine whether there exists a homeomorphism of Cantor space which sends one measure to the other, answering a question of Oxtoby. We then provide examples, relating these results to the notions of good and refinable measures on Cantor space.