bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction: governmentality, house numbering and the spatial history of the modern city
Authors: ROSE-REDWOOD REUBEN , TANTNER ANTON
Published: October 2012

This special section of Urban History explores the spatial histories of urban house numbering and the calculative rationalities of government since the Enlightenment. More than a mere footnote to the history of postal communications, the house number was first introduced as an inscriptive device to serve a wide range of governmental purposes, from military conscription and the quartering of soldiers to census-taking and the policing of urban populations. The spatial practice of house numbering can therefore be seen as a ‘political technology’ that was developed to reorganize urban space according to the dictates of numerical calculation. The articles in this special section examine the historical emergence of house numbering, and related practices, in different geographical circumstances, illustrating the spatial strategies of governmentality and the tactics of resistance that shaped the spatial organization of the modern city.
Numbering the streetscape: mapping the spatial history of numerical street names in Europe
Authors: VUOLTEENAHO JANI
Published: October 2012

In contrast to North American cities, numerically named streets are a very rare occurrence in Europe. This article explores the exceptions to this rule by charting the history of street numbering in 10 European countries. The medieval and early modern ‘new towns’ of New Winchelsea, Mannheim and a section of St Petersburg (Vasilievsky Island) were each designed with grid-plan layouts in which the streets were identified according to an alphanumerical system. Although a range of gridiron plans have been subsequently built across the continent, the newer instances of street numbering are characteristically inconspicuous and peripherally located in suburbs or industrial estates. As a result, most European cases of street numbering play a limited role in constituting the broader urban fabric of the streetscape, with the exception of cities such as Milton Keynes that conform more to the North American model. The relative absence of street-numbering plans in European cities can largely be explained by the much longer history of urbanism in Europe compared to North America and, above all else, the privileging of the nationalistic-pedagogic imperative to name streets with the aim of instilling historical ‘lessons’, which has left little room for the use of street numbering as a means of rationalizing the spatial organization of European cities.
The law of belligerent occupation in the Supreme Court of Israel
Authors: Kretzmer David
Published: October 2012

Since the 1967 War, in the course of which Israel occupied the West Bank and Gaza, the Supreme Court of Israel has considered thousands of petitions relating to acts of the military and other authorities in those territories (OT). This article reviews the contribution to the law of belligerent occupation of the Court's jurisprudence in these cases. After discussing issues of jurisdiction and the applicable norms, the article reviews the way in which the Court has interpreted military needs, the welfare of the local population, changes in the local law, and use of resources; the attitude of the Court to the long-term nature of the occupation and the existence of Israeli settlements, settlers, and commuters in the OT; the introduction of a three-pronged test of proportionality in assessing military necessity; and hostilities in occupied territories. In the final section, I draw some general conclusions on the Court's contribution to the law of occupation.
Geological context and vents morphology of the ultramafic‐hosted Ashadze hydrothermal areas (Mid‐Atlantic Ridge 13°N)
Authors: Ondréas Hélène , Cannat Mathilde , Fouquet Yves , Normand Alain
Published: October 2012

Recent ROV dives and high‐resolution bathymetric data acquired over the Ashadze fields on the Mid‐Atlantic Ridge (13°N) allow us to derive constraints on the regional and local geological setting of ultramafic‐hosted hydrothermal fields. The active vent fields of Ashadze hydrothermal fields are located in the western axial valley wall, downslope from the termination of a prominent corrugated surface and in a transitional domain with respect to ridge segmentation. The study of the shipboard and ROV bathymetry shows that decameter (100 m by 60 m) to kilometer‐scaled rockslides shape the axial valley wall slopes in this region. The Ashadze 1 vent field occurs on a coherent granular landslide rock mass that is elongated in an E‐W direction. The Ashadze 1 vent field comprises hundreds of active and inactive sulfide chimneys. The Ashadze 2 vent field is located in a NNE‐trending linear depression which separates outcrops of gabbros and serpentinized peridotites. Active black smokers in the Ashadze 2 field are located on ultramafic substratum in a 40‐m diameter crater, 5‐m deep. This crater recalls similar structures described at some vents of the Logatchev hydrothermal field (Mid‐Atlantic Ridge 15°N). We discuss the mode of formation for these craters, as well as that for a breadcrust‐like array of radial fissures identified at Ashadze 1. We propose that hydrothermalism at Ashadze can be an explosive phenomena associated with geyser‐like explosions. Our study also constrains the geological and geophysical context of the ultramafic‐hosted Ashadze hydrothermal system that may use the oceanic detachment fault as a preferred permeability conduit.
Mediterranean precipitation climatology, seasonal cycle, and trend as simulated by CMIP5
Authors: Kelley Colin , Ting Mingfang , Seager Richard , Kushnir Yochanan
Published: October 2012

Winter and summer Mediterranean precipitation climatology and trends since 1950 as simulated by the newest generation of global climate models, the Coupled Model Intercomparison Project phase 5 (CMIP5), are evaluated with respect to observations and the previous generation of models (CMIP3) used in the Intergovernmental Panel on Climate Change Fourth Assessment Report. Observed precipitation in the Mediterranean region is defined by wet winters and drier summers, and is characterized by substantial spatial and temporal variability. The observed drying trend since 1950 was predominantly due to winter drying, with very little contribution from the summer. However, in the CMIP5 multimodel mean, the precipitation trend since 1950 is evenly divided throughout the seasonal cycle. This may indicate that in observation, multidecadal internal variability, particularly that associated with the North Atlantic Oscillation (NAO), dominates the wintertime trend. An estimate of the observed externally forced trend shows that winter drying dominates in observations but the spatial patterns are grossly similar to the multimodel mean trend. The similarity is particularly robust in the eastern Mediterranean region, indicating a radiatively forced component being stronger there. Results of this study also reveal modest improvement for the CMIP5 multi‐model ensemble in representation of the observed six month winter and summer climatology. The results of this study are important for assessment of model predictions of hydroclimate change in the Mediterranean region, often referred to as a “hotspot” of future subtropical drying.
Quantifying the azimuthal plasmaspheric density structure and dynamics inferred from IMAGE EUV
Authors: Sibanda Patrick , Moldwin Mark B. , Galvan David A. , Sandel Bill R. , Forrester Terry
Published: October 2012

The extreme ultraviolet (EUV) imager on the IMAGE satellite provided the first global images of the plasmasphere leading to enhanced understanding of plasmapause structure and dynamics. However, few studies have investigated the structure and dynamics of the inner plasmasphere (regions interior to the plasmapause), which previous in situ observations have shown to often be highly structured. This study is the first to systematically analyze global images of the density structure of the inner plasmasphere by using data from the EUV imager on the IMAGE satellite. We find that the inner plasmasphere exhibits both fine and meso‐scale structure characterized by rapid density fluctuations and density enhancements of varying amplitudes (factors of ∼ 2–5) and spatial scales (from 10 s of minutes to 6 hours MLT) that occur regularly in the aftermath of geomagnetic storms. The level of variability within the azimuthal structure was found to increase with increasing geomagnetic activity. The observations suggest that some meso‐scale azimuthal density structure observed in the inner plasmasphere is from “fossil” plasmapause features entrained inside the expanding and refilling plasmasphere.
Storm‐time electron density enhancement in the cleft ion fountain
Authors: Kitamura N. , Nishimura Y. , Chandler M. O. , Moore T. E. , Terada N. , Ono T. , Shinbori A. , Kumamoto A.
Published: October 2012

To determine the characteristics and origin of observed storm‐time electron density enhancements in the polar cap, and to investigate the spatial extent (noon‐midnight direction) of associated O+ ion outflows, we analyzed nearly simultaneous observations of such electron density enhancements from the Akebono satellite and ion upflows from the Polar satellite during a geomagnetic storm occurring on 6 April 2000. The Akebono satellite observed substantial electron density enhancements by a factor of ∼10–90 with a long duration of ∼15 h at ∼2 RE in the southern polar region. The Polar satellite outflow measurements in the northern polar cap at ∼7–4 RE exhibited velocity filtering of the ∼100 eV to ∼0 eV (from the spacecraft potential) ion outflow from the cleft ion fountain, with resultant temperatures declining from ∼3 eV to 0.03 eV with increasing distance from the cusp. Similar velocity filtering was detected in the southern polar cap at ∼1.8–3.5 RE. The region of O+ ion outflows with fluxes exceeding 5×108 /cm2/s (mapped to 1000 km altitude) extended ∼10° MLAT (∼1000 km) at the ionosphere from the cusp/cleft into the dayside polar cap at ∼2.5 RE. These coordinated Akebono‐Polar observations are consistent with the development of storm‐time electron density enhancements in the polar cap as a result of the bulk outflow of low‐energy plasma as part of the cleft ion fountain. The large spatial scale, large ion fluxes, and the long duration indicate significant supply of very‐low‐energy O+ ions to the magnetosphere through this region.
Global abundance of microbial rhodopsins
Authors: Finkel Omri M , Béjà Oded , Belkin Shimshon
Published: October 2012

Photochemical reaction centers and rhodopsins are the only phototrophic mechanisms known to have evolved on Earth. The minimal cost of bearing a rhodopsin-based phototrophic mechanism in comparison to maintaining a photochemical reaction center suggests that rhodopsin is the more abundant of the two. We tested this hypothesis by conducting a global abundance calculation of phototrophic mechanisms from 116 marine and terrestrial microbial metagenomes. On average, 48% of the cells from which these metagenomes were generated harbored a rhodopsin gene, exceeding the reaction center abundance by threefold. Evidence from metatranscriptomic data suggests that this genomic potential is realized to a substantial extent, at least for the small-sized (>0.8 μm) of microbial fractions.
New perspectives on viable microbial communities in low-biomass cleanroom environments
Authors: Vaishampayan Parag , Probst Alexander J , La Duc Myron T , Bargoma Emilee , Benardini James N , Andersen Gary L , Venkateswaran Kasthuri
Published: October 2012

The advent of phylogenetic DNA microarrays and high-throughput pyrosequencing technologies has dramatically increased the resolution and accuracy of detection of distinct microbial lineages in mixed microbial assemblages. Despite an expanding array of approaches for detecting microbes in a given sample, rapid and robust means of assessing the differential viability of these cells, as a function of phylogenetic lineage, remain elusive. In this study, pre-PCR propidium monoazide (PMA) treatment was coupled with downstream pyrosequencing and PhyloChip DNA microarray analyses to better understand the frequency, diversity and distribution of viable bacteria in spacecraft assembly cleanrooms. Sample fractions not treated with PMA, which were indicative of the presence of both live and dead cells, yielded a great abundance of highly diverse bacterial pyrosequences. In contrast, only 1% to 10% of all of the pyrosequencing reads, arising from a few robust bacterial lineages, originated from sample fractions that had been pre-treated with PMA. The results of PhyloChip analyses of PMA-treated and -untreated sample fractions were in agreement with those of pyrosequencing. The viable bacterial population detected in cleanrooms devoid of spacecraft hardware was far more diverse than that observed in cleanrooms that housed mission-critical spacecraft hardware. The latter was dominated by hardy, robust organisms previously reported to survive in oligotrophic cleanroom environments. Presented here are the findings of the first ever comprehensive effort to assess the viability of cells in low-biomass environmental samples, and correlate differential viability with phylogenetic affiliation.
Promoter analysis of the DHCR24 (3β-hydroxysterol Δ24-reductase) gene: characterization of SREBP (sterol-regulatoryelement-binding protein)-mediated activation
Authors: Daimiel Lidia A. , Fernández-Suárez María E. , Rodríguez-Acebes Sara , Crespo Lorena , Lasunción Miguel A. , Gómez-Coronado Diego , Martínez-Botas Javier
Published: October 2012

DHCR24 (3β-hydroxysterol Δ24-reductase) catalyses the reduction of the C-24 double bond of sterol intermediates during cholesterol biosynthesis. DHCR24 has also been involved in cell growth, senescence and cellular response to oncogenic and oxidative stress. Despite its important roles, little is known about the transcriptional mechanisms controlling DHCR24 gene expression. We analysed the proximal promoter region and the cholesterol-mediated regulation of DHCR24. A putative SRE (sterol-regulatory element) at −98/−90 bp of the transcription start site was identified. Other putative regulatory elements commonly found in SREBP (SRE-binding protein)-targeted genes were also identified. Sterol responsiveness was analysed by luciferase reporter assays of approximately 1 kb 5′-flanking region of the human DHCR24 gene in HepG2 and SK-N-MC cells. EMSAs (electrophoretic mobility-shift assays) and ChIP (chromatin immunoprecipitation) assays demonstrated cholesterol-dependent recruitment and binding of SREBPs to the putative SRE. Given the presence of several CACCC-boxes in the DHCR24 proximal promoter, we assessed the role of KLF5 (Krüppel-like factor 5) in androgen-regulated DHCR24 expression. DHT (dihydrotestosterone) increased DHCR24 expression synergistically with lovastatin. However, DHT was unable to activate the DHCR24 proximal promoter, whereas KLF5 did, indicating that this mechanism is not involved in the androgen-induced stimulation of DHCR24 expression. The results of the present study allow the elucidation of the mechanism of regulation of the DHCR24 gene by cholesterol availability and identification of other putative cis-acting elements which may be relevant for the regulation of DHCR24 expression.
Simple tuning of carrier type in topological insulator Bi2Se3 by Mn doping
Authors: Choi Y. H. , Jo N. H. , Lee K. J. , Lee H. W. , Jo Y. H. , Kajino J. , Takabatake T. , Ko K.-T. , Park J.-H. , Jung M. H.
Published: October 2012

Bi2Te3 is a well-known thermoelectric material for room-temperature operations because it has a high Seebeck coefficient, and the charge carrier type is easily tunable. However, the carrier type of Bi2Se3 is not tunable, which is one of the weaknesses for the thermoelectric applications, in spite of its high Seebeck coefficient. Here, we report the tuning of charge carriers in Bi2Te3 from n type to p type by doping Mn into the Bi sites. The carrier type is n type up to the Mn doping level of 5% and changes to p type above 5% Mn doping. The temperature-dependent resistivity of Bi2−xMnxSe3 shows a metallic behavior for x < 0.05, while for x ≥ 0.05, it shows an upturn at low temperatures. This provides evidence that by Mn doping, the Fermi level is continuously tuned from the bulk conduction band to the bulk valence band. The Seebeck coefficient increases monotonically with increasing temperature, and the absolute values are same for both n- and p-type samples. This implies that Bi2Se3 is another candidate of high-temperature thermoelectric materials, like Bi2Te3, simply by Mn doping.
Effect of pressure on the ionic conductivity of Li+ and Cl− ions in water
Authors: Varanasi Srinivasa R. , Kumar Parveen , Subramanian Yashonath
Published: October 2012

A molecular dynamics simulation study of aqueous solution of LiCl is reported as a function of pressure. Experimental measurements of conductivity of Li+ ion as a function of pressure shows an increase in conductivity with pressure. Our simulations are able to reproduce the observed trend in conductivity. A number of relevant properties have been computed in order to understand the reasons for the increase in conductivity with pressure. These include radial distribution function, void and neck distributions, hydration or coordination numbers, diffusivity, velocity autocorrelation functions, angles between ion-oxygen and dipole of water as well as OH vector, mean residence time for water in the hydration shell, etc. These show that the increase in pressure acts as a structure breaker. The decay of the self part of the intermediate scattering function at small wave number k shows a bi-exponential decay at 1 bar which changes to single exponential decay at higher pressures. The k dependence of the ratio of the self part of the full width at half maximum of the dynamic structure factor to 2Dk2 exhibits trends which suggest that the void structure of water is playing a role. These support the view that the changes in void and neck distributions in water can account for changes in conductivity or diffusivity of Li+ with pressure. These results can be understood in terms of the levitation effect.
On the flow field about an electrophoretic particle
Authors: Orsini Gabriele , Tricoli Vincenzo
Published: October 2012

The flow field about an electrophoretic body is theoretically investigated by analytical methods. An effective boundary condition for the electric potential at particle surface is derived. This condition, which generalizes the one obtained by Levich [Physicochemical Hydrodynamics (Prentice-Hall, Englewood Cliffs, 1962), Chap. 9, p. 475], captures the effect of (convective and electromigratory) surface current in the Debye layer and is valid as far as it is legitimate to neglect ion-concentration gradient in the bulk liquid. Conditions for negligible concentration gradients are also presented and discussed. The effect of surface current determines a deviation from Morrison's “classical” theory, which predicts irrotational flow-field for any particle shape with electrophoretic velocity given by the well-known Smoluchowski formula and always directed along the applied electric field. It is shown here that in the presence of the above effect the irrotationality of the flow field is not preserved if the particle surface has non-uniform curvature. However, irrotational flow-field still subsists for a sphere and a cylinder and is analytically determined in terms of a new non-dimensional parameter, referred to as the electrophoretic number. The case of spheroidal objects is also examined in detail. In this case the flow field, though not strictly irrotational, is shown to be nearly approximated by an irrotational flow-field, which is also determined over wide ranges of electrophoretic number and spheroid aspect ratio. The quality of this approximation is expressed as a relative error on the Helmholtz-Smoluchowski condition and numerically evaluated both in longitudinal and transverse configuration. The limiting cases of spheroid degenerating into a needle and a disk are also addressed. In all above cases the respective mobilities deviate from Smoluchowski's formula and depend on the electrophoretic number. An important effect of surface ion-transport in the double layer is anisotropy of electrophoretic mobility for non-spherical objects. That always bears a bias of the electrophoretic velocity with respect to the applied electric field when the latter is not collinear with a symmetry axis of the body. For a cylinder, bias is always toward the axis. For a spheroid, it is generally toward the polar axis; however, bias toward the equatorial axis is predicted for moderately oblate spheroids. In general, the bias angle is remarkable, which is of potential consequence in technical applications of electrophoresis. Comparison of results of the present theory with experimental work from the literature is presented and discussed.
Two infrared emission modes with different wavelengths and orthogonal polarization in a waveguide thermal emitter
Authors: Chen Hung-Hsin , Chang Yi-Tsung , Huang Shao-Yu , Chuang Fang-Tzu , Yu Chih-Wei , Lee Si-Chen
Published: October 2012

This study investigates a Au/SiO2/Au waveguide thermal emitter incorporating a metallic grating embedded in the SiO2 layer. The metal grating acts as a beam splitter, dividing the device into two waveguide structures determined by the polarization of the waveguide modes. The thermal radiation spectrum exhibits two peaks with orthogonal polarization. The emitted wavelengths of the two waveguide modes can be adjusted by controlling the thickness of the SiO2 layers on both sides of the metallic grating during the fabrication process. The emission peaks have ratios of the full width at half maximum to the peak wavelength of 0.057 and 0.05 for the TE and TM polarizations, respectively. These characteristics show the suitability of the device for multi-peaks and narrow bandwidth infrared light source applications.
Modified Shepard interpolation of gas-surface potential energy surfaces with strict plane group symmetry and translational periodicity
Authors: Frankcombe Terry J. , Collins Michael A. , Zhang Dong H.
Published: October 2012

A new formulation of modified Shepard interpolation of potential energy surface data for gas-surface reactions has been developed. The approach has been formulated for monoatomic or polyatomic adsorbates interacting with crystalline solid surfaces of any plane group symmetry. The interpolation obeys the two dimensional translational periodicity and plane group symmetry of the solid surface by construction. The interpolation remains continuous and smooth everywhere. The interpolation developed here is suitable for constructing potential energy surfaces by sampling classical trajectories using the Grow procedure. A model function has been used to demonstrate the method, showing the convergence of the classical gas-surface reaction probability.
Local unitary transformation method for large-scale two-component relativistic calculations. II. Extension to two-electron Coulomb interaction
Authors: Seino Junji , Nakai Hiromi
Published: October 2012

The local unitary transformation (LUT) scheme at the spin-free infinite-order Douglas–Kroll-Hess (IODKH) level [J. Seino and H. Nakai, J. Chem. Phys. 136, 244102 (2012)10.1063/1.4729463], which is based on the locality of relativistic effects, has been extended to a four-component Dirac–Coulomb Hamiltonian. In the previous study, the LUT scheme was applied only to a one-particle IODKH Hamiltonian with non-relativistic two-electron Coulomb interaction, termed IODKH/C. The current study extends the LUT scheme to a two-particle IODKH Hamiltonian as well as one-particle one, termed IODKH/IODKH, which has been a real bottleneck in numerical calculation. The LUT scheme with the IODKH/IODKH Hamiltonian was numerically assessed in the diatomic molecules HX and X2 and hydrogen halide molecules, (HX)n (X = F, Cl, Br, and I). The total Hartree–Fock energies calculated by the LUT method agree well with conventional IODKH/IODKH results. The computational cost of the LUT method is reduced drastically compared with that of the conventional method. In addition, the LUT method achieves linear-scaling with respect to the system size and a small prefactor.
Bayesian uncertainty quantification and propagation in molecular dynamics simulations: A high performance computing framework
Authors: Angelikopoulos Panagiotis , Papadimitriou Costas , Koumoutsakos Petros
Published: October 2012

We present a Bayesian probabilistic framework for quantifying and propagating the uncertainties in the parameters of force fields employed in molecular dynamics (MD) simulations. We propose a highly parallel implementation of the transitional Markov chain Monte Carlo for populating the posterior probability distribution of the MD force-field parameters. Efficient scheduling algorithms are proposed to handle the MD model runs and to distribute the computations in clusters with heterogeneous architectures. Furthermore, adaptive surrogate models are proposed in order to reduce the computational cost associated with the large number of MD model runs. The effectiveness and computational efficiency of the proposed Bayesian framework is demonstrated in MD simulations of liquid and gaseous argon.
Organic light-emitting diodes with direct contact-printed red, green, blue, and white light-emitting layers
Authors: Chen Sun-Zen , Peng Shiang-Hau , Ting Tzu-Yu , Wu Po-Shien , Lin Chun-Hao , Chang Chin-Yeh , Shyue Jing-Jong , Jou Jwo-Huei
Published: October 2012

We demonstrate the feasibility of using direct contact-printing in the fabrication of monochromatic and polychromatic organic light-emitting diodes (OLEDs). Bright devices with red, green, blue, and white contact-printed light-emitting layers with a respective maximum luminance of 29 000, 29 000, 4000, and 18 000 cd/m2 were obtained with sound film integrity by blending a polymeric host into a molecular host. For the red OLED as example, the maximum luminance was decreased from 29 000 to 5000 cd/m2 as only the polymeric host was used, or decreased to 7000 cd/m2 as only the molecular host was used. The markedly improved device performance achieved in the devices with blended hosts may be attributed to the employed polymeric host that contributed a good film-forming character, and the molecular host that contributed a good electroluminescence character.
Theory of photoferroelectric response in SmC* liquids
Authors: Knežević Miloš , Warner Mark
Published: October 2012

We are concerned with the modification of liquid crystalline and polar order in chiral smectic C liquids by illumination. In particular we show that spatial non-uniformity of order and electric polarization due to light absorption and also dynamics can be complex. The variation of polarization with temperature, while illuminated, is modified from that assuming uniformity. The dynamics is shown to depend on propagating fronts of photoconversion penetrating the sample. Apparent changes of ferroelectric polarization with illumination will be shown to be underestimated due to non-uniformity.
The infrared spectrum of HOOH+ trapped in solid neon
Authors: Thompson Warren E. , Lugez Catherine L. , Jacox Marilyn E.
Published: October 2012

When a Ne:H2O2 mixture is codeposited at 4.3 K with a beam of neon atoms that have been excited in a microwave discharge, three new, photosensitive absorptions appear which can be assigned to the three infrared-active vibrational fundamentals of trans-HOOH+. When the Ne:H2O2 deposition system is pretreated with the vapors of D2O, the product absorptions include new peaks which can be attributed to vibrational fundamentals of trans-HOOD+ and trans-DOOD+. Density functional calculations of the vibrational fundamentals of the three hydrogen peroxide cation isotopologues support the proposed assignments. Broad, photosensitive product absorptions also appear near the positions of vibrational transitions of O3−, and may be contributed by a weakly bound complex of that species with H2O.
Wrapping transition and wrapping-mediated interactions for discrete binding along an elastic filament: An exact solution
Authors: Dean David S. , Hammant Thomas C. , Horgan Ronald R. , Naji Ali , Podgornik Rudolf
Published: October 2012

The wrapping equilibria of one and two adsorbing cylinders are studied along a semi-flexible filament (polymer) due to the interplay between elastic rigidity and short-range adhesive energy between the cylinder and the filament. We show that statistical mechanics of the system can be solved exactly using a path integral formalism which gives access to the full effect of thermal fluctuations, going thus beyond the usual Gaussian approximations which take into account only the contributions from the minimal energy configuration and small fluctuations about this minimal energy solution. We obtain the free energy of the wrapping-unwrapping transition of the filament around the cylinders as well as the effective interaction between two wrapped cylinders due to thermal fluctuations of the elastic filament. A change of entropy due to wrapping of the filament around the adsorbing cylinders as they move closer together is identified as an additional source of interactions between them. Such entropic wrapping effects should be distinguished from the usual entropic configuration effects in semi-flexible polymers. Our results may be relevant to the problem of adsorption of oriented nano-rods on semi-flexible polymers.
A novel approach for normalizing the photoreflectance spectrum by using polymer-dispersed liquid crystal
Authors: Liao Y. F. , Chang C. C. , Wang D. P. , Tseng B. H. , Liao Y. D. , Lin C. H.
Published: October 2012

This study developed a novel type of normalization procedure for modulation reflectance spectroscopy experiments to obtain the relative change in the reflectance spectrum, ΔR/R. This technique uses a polymer-dispersed liquid crystal to ensure that the dc component of the signal from the detector remained constant by varying the intensity of the light striking the sample. This method is particularly useful for photoreflectance measurement, which may encounter background problems because of scattered pump light and/or photoluminescence. It does not require a change in the gain of the detector or the use of a variable neutral density filter mounted on a servo-motor.
Note: Laser Doppler velocimeter using a dual-longitudinal-mode laser source
Authors: Xiaoming Nie , Jian Zhou , Xingwu Long
Published: October 2012

This paper presents a new laser Doppler technique using a dual-longitudinal-mode He-Ne laser as the laser source. Theoretical analysis shows that the Doppler frequency is proportional with the frequency difference of the two modes. The Doppler frequency in this technique is very low compared with the one in the single-mode laser Doppler technique. The new laser Doppler technique can be used to measure high speed. Experiment results show that the Doppler frequency is only about 82 Hz while the measurement speed reaches 31.4 m/s. The signal-to-noise ratio of the Doppler signal is improved by the technique of digital filter and digital autocorrelation.
A test stand for the evaluation of high efficiency mist eliminators
Authors: Giffin Paxton K. , Parsons Michael S. , Waggoner Charles A.
Published: October 2012

High efficiency mist eliminators (HEME) are airstream filtering elements primarily used to remove liquid and solid aerosols. HEME elements are designed to reduce aerosol load on downstream high efficiency particulate air filters and to have a liquid particle removal efficiency of 99.5% for aerosols as small as 1 μm in size. The test stand described herein is designed to evaluate the loading capacity and filtering efficiency of a single HEME element. The loading capacity was determined with or without use of a water spray cleaning system to wash the interior surface of the element. The HEME element is challenged with a liquid waste surrogate using Laskin nozzles and large dispersion nozzles. The waste surrogate used was a highly caustic solution with both suspended and dissolved solids representative of actual exposures at mixed, hazardous, and radiological, waste treatment facilities. The filtering efficiency performance was determined by challenging the element with a dried waste surrogate aerosol and di-octyl phthalate intermittently during the loading process. Capabilities of the test stand and representative results obtained during testing are presented.
A twisted integrable hierarchy with $\mathbb D_2$D2 symmetry
Authors: Wu Derchyi
Published: October 2012

A loop algebra approach to the Gerdjikov-Mikhailov-Valchev (GMV) equation is provided to exploit the associated twisted integrable structure and a new twisted integrable hierarchy is discovered. Using the twisted loop algebra structure, we obtain a transparent treatment of the associated scattering and inverse scattering theory and solve the initial value problem for the GMV equation.
Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content
Authors: Henrich D. , Dörner S. , Hofherr M. , Il'in K. , Semenov A. , Heintze E. , Scheffler M. , Dressel M. , Siegel M.
Published: October 2012

The spectral detection efficiency and the dark count rate of superconducting nanowire single-photon detectors (SNSPD) have been studied systematically on detectors made from thin NbN films with different chemical compositions. Reduction of the nitrogen content in the 4 nm thick NbN films results in a decrease of the dark count rates more than two orders of magnitude and in a red shift of the cut-off wavelength of the hot-spot SNSPD response. The observed phenomena are explained by an improvement of uniformity of NbN films that has been confirmed by a decrease of resistivity and an increase of the ratio of the measured critical current to the depairing current. The latter factor is considered as the most crucial for both the cut-off wavelength and the dark count rates of SNSPD. Based on our results we propose a set of criteria for material properties to optimize SNSPD in the infrared spectral region.
Modeling the formation of ordered nano-assemblies comprised by dendrimers and linear polyelectrolytes: The role of Coulombic interactions
Authors: Eleftheriou E. , Karatasos K.
Published: October 2012

Models of mixtures of peripherally charged dendrimers with oppositely charged linear polyelectrolytes in the presence of explicit solvent are studied by means of molecular dynamics simulations. Under the influence of varying strength of electrostatic interactions, these systems appear to form dynamically arrested film-like interconnected structures in the polymer-rich phase. Acting like a pseudo-thermodynamic inverse temperature, the increase of the strength of the Coulombic interactions drive the polymeric constituents of the mixture to a gradual dynamic freezing-in. The timescale of the average density fluctuations of the formed complexes initially increases in the weak electrostatic regime reaching a finite limit as the strength of electrostatic interactions grow. Although the models are overall electrically neutral, during this process the dendrimer/linear complexes develop a polar character with an excess charge mainly close to the periphery of the dendrimers. The morphological characteristics of the resulted pattern are found to depend on the size of the polymer chains on account of the distinct conformational features assumed by the complexed linear polyelectrolytes of different length. In addition, the length of the polymer chain appears to affect the dynamics of the counterions, thus affecting the ionic transport properties of the system. It appears, therefore, that the strength of electrostatic interactions together with the length of the linear polyelectrolytes are parameters to which these systems are particularly responsive, offering thus the possibility for a better control of the resulted structure and the electric properties of these soft-colloidal systems.
Hot-electron production and suprathermal heat flux scaling with laser intensity from the two-plasmon–decay instability
Authors: Vu H. X. , DuBois D. F. , Myatt J. F. , Russell D. A.
Published: October 2012

The fully kinetic reduced-description particle-in-cell (RPIC) method has been applied to simulations of two-plasmon–decay (TPD) instability, driven by crossed laser beams, in an inhomogeneous plasma for parameters consistent with recent direct-drive experiments related to laser-driven inertial fusion. The nonlinear saturated state is characterized by very spiky electric fields, with Langmuir cavitation occurring preferentially inside density channels produced by the ponderomotive beating of the crossed laser beams and the primary TPD Langmuir waves (LWs). The heated electron distribution function is, in all cases, bi-Maxwellian, with instantaneous hot-electron temperatures in the range 60–100 keV. The net hot-electron energy flux out of the system is a small fraction (∼1% to 2%) of the input laser intensity in these simulations. Scalings of the hot-electron temperature and suprathermal heat flux as functions of the laser intensity are obtained numerically from RPIC simulations. These simulations lead to the preliminary conclusion that Langmuir cavitation and collapse provide dissipation by producing suprathermal electrons, which stabilize the system in saturation and drive the LW spectrum to the small dissipation scales at the Landau cutoff. The Langmuir turbulence originates at an electron density 0.241× the laser's critical density, where the crossed laser beams excite a “triad” mode—a common forward LW plus a pair of backward LWs. Remnants of this “triad” evolve in k-space and dominate the time-averaged energy spectrum. At times exceeding 10 ps, the excited Langmuir turbulence spreads toward lower densities. Comparisons of RPIC simulations with the extended Zakharov model are presented in appropriate regimes, and the necessary requirements for the validity of a quasi-linear Zakharov model (where the spatially averaged electron-velocity distribution is evolved) are verified by RPIC simulation results.
Origin of kink effect in AlGaN/GaN high electron mobility transistors: Yellow luminescence and Fe doping
Authors: Killat N. , Uren M. J. , Wallis D. J. , Martin T. , Kuball M.
Published: October 2012

AlGaN/GaN high electron mobility transistors with different Fe-doping density were studied using electrical and optical analysis to gain insight into the nature of traps responsible for the kink effect in electrical characteristics. Kink effect has been previously suggested to result from direct trapping of carriers in defects related to yellow luminescence (YL) centers. However, the results demonstrate that YL is suppressed by Fe doping, whereas the kink effect is not affected to the same extent. YL related defect states are therefore not exclusively responsible for the kink effect, suggesting a more complex trapping mechanism to affect device output characteristics.
Terahertz emission from cubic semiconductor induced by a transient anisotropic photocurrent
Authors: Malevich V. L. , Ziaziulia P. A. , Adomavičius R. , Krotkus A. , Malevich Y. V.
Published: October 2012

Terahertz emission from the surfaces of narrow-gap semiconductors excited by femtosecond laser pulses was described in terms of a transient interband photoconductivity. It has been found that the nonparabolicity of the electron dispersion law as well as the optical alignment of the photoexcited carrier momenta result in anisotropic photocurrent with a component perpendicular to the surface dc electric field even in semiconductors with a cubic symmetry. This lateral transient photocurrent component is the strongest during the first few hundreds of femtoseconds after the photoexcitation and causes the emission of terahertz radiation pulses with an amplitude dependent on the angle between the optical field and the crystallographic axes. In the case of InAs the contribution of this component explains experimental results of both the azimuthal anisotropy of the emitted terahertz pulse amplitude and its dependence on the exciting photon energy.
Impact of induced bandgaps on sub-Poissonian shot noise in graphene armchair-edge nanoribbons
Authors: Xu G. J. , Zhu Y. M. , Wu B. H. , Xu X. G. , Cao J. C.
Published: October 2012

The impact of the bandgap induced by transversal constriction on the sub-Poissonian properties of graphene armchair-edge nanoribbons (GANRs) has been investigated in a theoretical perspective. For a typical GANR with a bandgap, the minimal conductivity at the Dirac point becomes more suppressed than that of the gapless case 4e2/πh, and the Fano factor becomes more enhanced than the originally predicted value 1/3. The amplitudes of conductivity suppression and Fano factor enhancement will grow large as the nanoribbon width decreases. And the variance of Fano factor is qualitatively consistent with the reported experimental data. The carriers of GANRs with gaps behave like counterparticles in a semiconductor, and the transition from the sub-Poissonian to a Poissonian process takes place gradually with the reduction of the nanoribbon width. For the low aspect ratio (the sample width over its length) limit, the shot noise property at the Dirac point is no longer sensitive to the boundary edges. For the high limit, it requires a larger aspect ratio for the minimal conductivity and maximal Fano factor to achieve stationary values than that of the gapless case.
Tailoring electron energy distribution functions through energy confinement in dual radio-frequency driven atmospheric pressure plasmas
Authors: O'Neill C. , Waskoenig J. , Gans T.
Published: October 2012

A multi-scale numerical model based on hydrodynamic equations with semi-kinetic treatment of electrons is used to investigate the influence of dual frequency excitation on the effective electron energy distribution function (EEDF) in a radio-frequency driven atmospheric pressure plasma. It is found that variations of power density, voltage ratio, and phase relationship provide separate control over the electron density and the mean electron energy. This is exploited to directly influence both the phase dependent and time averaged effective EEDF. This enables tailoring the EEDF for enhanced control of non-equilibrium plasma chemical kinetics at ambient pressure and temperature.
Helical domain walls in constricted cylindrical NiFe nanowires
Authors: Chandra Sekhar M. , Liew H. F. , Purnama I. , Lew W. S. , Tran M. , Han G. C.
Published: October 2012

Reducing the magnetic shape anisotropy of a cylindrical NiFe nanowire allows the formation of two vortices with opposite chirality at the two ends. At relatively low aspect ratio these two vortices are connected via a gradual rotation of the magnetization over a short region, which forms a three-dimensional helical domain wall. Micromagnetic simulations reveal that it is possible to control the number of helical domain walls in the cylindrical nanowire by geometrical constrictions engineering. A technique to create constricted Ni95Fe5/Ni87Fe13 multilayered nanowires is demonstrated, and magnetic force microscopy imaging was carried out to confirm the prediction of simulated helical domain walls.
Modified processing techniques of a DNA biopolymer for enhanced performance in photonics applications
Authors: Ouchen Fahima , Sotzing Gregory A. , Miller Trisha L. , Singh Kristi M. , Telek Brian A. , Lesko Alyssa C. , Aga Roberto , Fehrman-Cory Emily M. , Yaney Perry P. , Grote James G. , Bartsch Carrie M. , Heckman Emily M.
Published: October 2012

Significant modifications have been made in the processing techniques developed to transform purified, marine-based deoxyribonucleic acid (DNA) into a biopolymer suitable for optical and electronic device fabrication. This technique employs a modified soxhlet-dialysis rinsing process to completely remove excess ionic contaminants from the DNA biopolymer, resulting in a material with greater mechanical stability and enhanced performance reproducibility.
Influence of dissolved air on the adsorption properties and stability of vesicles on various surfaces
Authors: Seo Hyejung , Ko Wooree , Jeon Sangmin
Published: October 2012

Large unilamellar vesicles were prepared for adsorption on quartz crystal surfaces coated with gold, mercaptoundecanoic acid, or octadecanethiol self-assembled monolayers. The adsorption of the vesicles onto these surfaces decreases the resonance frequency of the quartz crystals. We found that frequency changes due to vesicle adsorption were much lower in degassed than in air-rich water. Further, the vesicles adsorbed in air-rich water desorbed when the medium was replaced with degassed water, indicating that the presence of dissolved air in water played a key role in the adsorption and stability of vesicles.
Rhenium oxide as an efficient p-dopant to overcome S-shaped current density-voltage curves in organic photovoltaics with a deep highest occupied molecular orbital level donor layer
Authors: Kim Dae-Ho , Kim Tae-Min , Jeong Won-Ik , Kim Jang-Joo
Published: October 2012

Effect of p-dopants in a p-doped hole transport layer inserted between indium tin oxide and a donor layer of α,α′-bis(2,2-dicyanovinyl)-quinquethiophene with a deep highest occupied molecular orbital level is reported to remove the S-shape in the organic photovoltaics (OPV) cell. Among the p-dopants of ReO3, MoO3, WO3, and CuI, ReO3 possesses the largest work function and turns out to be the most efficient p-dopant to remove the S-shape of the current density-voltage curve in the OPV cells. The rest of the dopants could not get rid of the S-shape, even with a doping concentration of 25 mol. %. The difference among the dopants can be understood by the different charge generation efficiency of the dopants.
Silver nanoisland enhanced Raman interaction in graphene
Authors: Urich Alexander , Pospischil Andreas , Furchi Marco M. , Dietze Daniel , Unterrainer Karl , Mueller Thomas
Published: October 2012

Graphene shows great potential for optoelectronic applications but suffers from rather weak interaction with light due its single-atomic thickness. Here, we report the enhanced interaction of graphene and light for Raman transitions using localized surface plasmons. The plasmons are generated in silver nanoislands that we fabricate by simple means of metal deposition on top of graphene. Despite the broad size distribution of the nanoislands, we find a 100-fold enhancement of the Raman signal. We provide an analytical model for the description of the optical properties and obtain the scattering cross section as well as enhancement factors for the Raman transitions. In addition, we investigate, both optically and electrically, the doping that is introduced by the nanoislands.
Communication: Direct determination of triple-point coexistence through cell model simulation
Authors: Heng Vincent R. , Nayhouse Michael , Crose Marquis , Tran Anh , Orkoulas G.
Published: October 2012

In simulations of fluid-solid coexistence, the solid phase is modeled as a constrained system of Wigner-Seitz cells with one particle per cell. This model, commonly referred to as the constrained cell model, is a limiting case of a more general cell model, which is formed by considering a homogeneous external field that controls the number of particles per cell and, hence, the relative stability of the solid against the fluid phase. The generalized cell model provides a link that connects the disordered, fluid phase with the ordered, solid phase. In the present work, the phase diagram of this model is investigated through multicanonical simulations at constant pressure and histogram reweighting techniques for a system of 256 Lennard-Jones particles. The simulation data are used to obtain an estimate of the triple point of the Lennard-Jones system. The triple-point pressure is found to be higher compared to previous work. The likely explanation for this discrepancy is the highly compressible nature of the gas phase.