bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase stability of ScN-based solid solutions for thermoelectric applications from first-principles calculations
Authors: Kerdsongpanya Sit , Alling Björn , Eklund Per
Published: August 2013

We have used first-principles calculations to investigate the trends in mixing thermodynamics of ScN-based solid solutions in the cubic B1 structure. 13 different Sc1−xMxN (M = Y, La, Ti, Zr, Hf, V, Nb, Ta, Gd, Lu, Al, Ga, In) and three different ScN1−xAx (A = P, As, Sb) solid solutions are investigated and their trends for forming disordered or ordered solid solutions or to phase separate are revealed. The results are used to discuss suitable candidate materials for different strategies to reduce the high thermal conductivity in ScN-based systems, a material having otherwise promising thermoelectric properties for medium and high temperature applications. Our results indicate that at a temperature of T = 800 °C, Sc1−xYxN; Sc1−xLaxN; Sc1−xGdxN, Sc1−xGaxN, and Sc1−xInxN; and ScN1−xPx, ScN1−xAsx, and ScN1−xSbx solid solutions have phase separation tendency, and thus, can be used for forming nano-inclusion or superlattices, as they are not intermixing at high temperature. On the other hand, Sc1−xTixN, Sc1−xZrxN, Sc1−xHfxN, and Sc1−xLuxN favor disordered solid solutions at T = 800 °C. Thus, the Sc1−xLuxN system is suggested for a solid solution strategy for phonon scattering as Lu has the same valence as Sc and much larger atomic mass.
Directed translocation of a flexible polymer through a cone-shaped nano-channel
Authors: Nikoofard Narges , Khalilian Hamidreza , Fazli Hossein
Published: August 2013

Translocation of a flexible polymer through a cone-shaped channel is studied, theoretically and using computer simulations. Our simulations show that the shape of the channel causes the polymer translocation to be a driven process. The effective driving force of entropic origin acting on the polymer is calculated as a function of the length and the apex-angle of the channel, theoretically. It is found that the translocation time is a non-monotonic function of the apex-angle of the channel. By increasing the apex-angle from zero, the translocation time shows a minimum and then a maximum. Also, it is found that regardless of the value of the apex-angle, the translocation time is a uniformly decreasing function of the channel length. The results of the theory and the simulation are in good qualitative agreement.
Electric-field-induced response of a droplet embedded in a polyelectrolyte gel
Authors: Mohammadi Aliasghar
Published: August 2013

The electric-field induced response of a droplet embedded in a quenched polyelectrolyte gel is calculated theoretically. The response comprises the droplet translation and the electric-field induced flow fields within the droplet. The gel is modeled as a soft, and electrically charged porous solid saturated with a salted Newtonian fluid. The droplet is considered an incompressible Newtonian fluid with no free charge. An analytical solution, using the perturbation methodology and linear superposition, is obtained for the leading-order steady response to a DC electric-field. The fluid within the droplet is driven due to hydrodynamic coupling with the electroosmotic flow. The fluid velocity within the droplet is linearly proportional to the electroosmotic flow. Moreover, the microrheological response function of a droplet within a polyelectrolyte gel is also provided, highlighting the importance of boundary conditions at the droplet-gel interface on microrheological measurements.
Effect of contact area on electron transport through graphene-metal interface
Authors: Liu Hongmei , Kondo Hisashi , Ohno Takahisa
Published: August 2013

We perform first-principles investigations of electron transport in armchair graphene nanoribbons adsorbed on Cu(111) and Ni(111) surfaces with various contact areas. We find that the contact area between metals and graphene has different influences on the conductance. The Cu-graphene system shows an increase in differential conductance for more contact area at a low bias voltage, primarily originating from the shift of transmission peaks relative to the Fermi energy. As the bias increases, there is an irregular change of conductance, including a weak negative differential conductance for more contact area. In contrast, the conductance of the Ni-graphene junction is monotonically enhanced with increasing overlap area. The minority spin which shows a broad transmission is responsible for the conductance increase of Ni-graphene. These behaviors can be attributed to different mechanisms of the interfacial electron transport: Charge transfer between graphene and Cu largely dominates the transmission enhancement of Cu-graphene, whereas hybridization between graphene and Ni states plays a more important role in the transmission enhancement of Ni-graphene. The different behaviors of transmission increase correlate with not only the strength of the graphene-metal interaction but also the location of metal d states.
Information-theoretic tools for parametrized coarse-graining of non-equilibrium extended systems
Authors: Katsoulakis Markos A. , Plecháč Petr
Published: August 2013

In this paper, we focus on the development of new methods suitable for efficient and reliable coarse-graining of non-equilibrium molecular systems. In this context, we propose error estimation and controlled-fidelity model reduction methods based on Path-Space Information Theory, combined with statistical parametric estimation of rates for non-equilibrium stationary processes. The approach we propose extends the applicability of existing information-based methods for deriving parametrized coarse-grained models to Non-Equilibrium systems with Stationary States. In the context of coarse-graining it allows for constructing optimal parametrized Markovian coarse-grained dynamics within a parametric family, by minimizing information loss (due to coarse-graining) on the path space. Furthermore, we propose an asymptotically equivalent method—related to maximum likelihood estimators for stochastic processes—where the coarse-graining is obtained by optimizing the information content in path space of the coarse variables, with respect to the projected computational data from a fine-scale simulation. Finally, the associated path-space Fisher Information Matrix can provide confidence intervals for the corresponding parameter estimators. We demonstrate the proposed coarse-graining method in (a) non-equilibrium systems with diffusing interacting particles, driven by out-of-equilibrium boundary conditions, as well as (b) multi-scale diffusions and the corresponding stochastic averaging limits, comparing them to our proposed methodologies.
Molecular dynamics simulation of a single-stranded DNA with heterogeneous distribution of nucleobases in aqueous medium
Authors: Chakraborty Kaushik , Mantha Sriteja , Bandyopadhyay Sanjoy
Published: August 2013

The DNA metabolic processes often involve single-stranded DNA (ss-DNA) molecules as important intermediates. In the absence of base complementarity, ss-DNAs are more flexible and interact strongly with water in aqueous media. Ss-DNA–water interactions are expected to control the conformational flexibility of the DNA strand, which in turn should influence the properties of the surrounding water molecules. We have performed room temperature molecular dynamics simulation of an aqueous solution containing the ss-DNA dodecamer, 5′-CGCGAATTCGCG-3′. The conformational flexibility of the DNA strand and the microscopic structure and ordering of water molecules around it have been explored. The simulation reveals transformation of the initial base-stacked form of the ss-DNA to a fluctuating collapsed coil-like conformation with the formation of a few non-sequentially stacked base pairs. A preliminary analysis shows further collapse of the DNA conformation in presence of additional salt (NaCl) due to screening of negative charges along the backbone by excess cations. Additionally, higher packing of water molecules within a short distance from the DNA strand is found to be associated with realignment of water molecules by breaking their regular tetrahedral ordering.
Structural properties of fluids interacting via piece-wise constant potentials with a hard core
Authors: Santos Andrés , Yuste Santos B. , de Haro Mariano López , Bárcenas Mariana , Orea Pedro
Published: August 2013

The structural properties of fluids whose molecules interact via potentials with a hard core plus two piece-wise constant sections of different widths and heights are presented. These follow from the more general development previously introduced for potentials with a hard core plus n piece-wise constant sections [A. Santos, S. B. Yuste, and M. Lopez de Haro, Condens. Matter Phys. 15, 23602 (2012)]10.5488/CMP.15.23602 in which use was made of a semi-analytic rational-function approximation method. The results of illustrative cases comprising eight different combinations of wells and shoulders are compared both with simulation data and with those that follow from the numerical solution of the Percus–Yevick and hypernetted-chain integral equations. It is found that the rational-function approximation generally predicts a more accurate radial distribution function than the Percus–Yevick theory and is comparable or even superior to the hypernetted-chain theory. This superiority over both integral equation theories is lost, however, at high densities, especially as the widths of the wells and/or the barriers increase.
Electron density and electron temperature measurement in a bi-Maxwellian electron distribution using a derivative method of Langmuir probes
Authors: Choi Ikjin , Chung ChinWook , Youn Moon Se
Published: August 2013

In plasma diagnostics with a single Langmuir probe, the electron temperature Te is usually obtained from the slope of the logarithm of the electron current or from the electron energy probability functions of current (I)-voltage (V) curve. Recently, Chen [F. F. Chen, Phys. Plasmas 8, 3029 (2001)] suggested a derivative analysis method to obtain Te by the ratio between the probe current and the derivative of the probe current at a plasma potential where the ion current becomes zero. Based on this method, electron temperatures and electron densities were measured and compared with those from the electron energy distribution function (EEDF) measurement in Maxwellian and bi-Maxwellian electron distribution conditions. In a bi-Maxwellian electron distribution, we found the electron temperature Te obtained from the method is always lower than the effective temperatures Teff derived from EEDFs. The theoretical analysis for this is presented.
Large scale molecular dynamics simulations of homogeneous nucleation
Authors: Diemand Jürg , Angélil Raymond , Tanaka Kyoko K. , Tanaka Hidekazu
Published: August 2013

We present results from large-scale molecular dynamics (MD) simulations of homogeneous vapor-to-liquid nucleation. The simulations contain between 1 × 109 and 8 × 109 Lennard-Jones (LJ) atoms, covering up to 1.2 μs (56 × 106 time-steps). They cover a wide range of supersaturation ratios, S ≃ 1.55–104, and temperatures from kT = 0.3 to 1.0ε (where ε is the depth of the LJ potential, and k is the Boltzmann constant). We have resolved nucleation rates as low as 1017 cm−3 s−1 (in the argon system), and critical cluster sizes as large as 100 atoms. Recent argon nucleation experiments probe nucleation rates in an overlapping range, making the first direct comparison between laboratory experiments and molecular dynamics simulations possible: We find very good agreement within the uncertainties, which are mainly due to the extrapolations of argon and LJ saturation curves to very low temperatures. The self-consistent, modified classical nucleation model of Girshick and Chiu [J. Chem. Phys. 93, 1273 (1990)]10.1063/1.459191 underestimates the nucleation rates by up to 9 orders of magnitudes at low temperatures, and at kT = 1.0ε it overestimates them by up to 105. The predictions from a semi-phenomenological model by Laaksonen et al. [Phys. Rev. E 49, 5517 (1994)]10.1103/PhysRevE.49.5517 are much closer to our MD results, but still differ by factors of up to 104 in some cases. At low temperatures, the classical theory predicts critical clusters sizes, which match the simulation results (using the first nucleation theorem) quite well, while the semi-phenomenological model slightly underestimates them. At kT = 1.0ε, the critical sizes from both models are clearly too small. In our simulations the growth rates per encounter, which are often taken to be unity in nucleation models, lie in a range from 0.05 to 0.24. We devise a new, empirical nucleation model based on free energy functions derived from subcritical cluster abundances, and find that it performs well in estimating nucleation rates.
Characterization of amorphous Si-Zn-Sn-O thin films and applications in thin-film transistors
Authors: Wu Chuanjia , Li Xifeng , Lu Jianguo , Ye Zhizhen , Zhang Jie , Zhou Tingting , Sun Rujie , Chen Lingxiang , Lu Bin , Pan Xinhua
Published: August 2013

Amorphous silicon-zinc-tin-oxide (α-SZTO) thin films were prepared, and their properties were investigated physically and electrically, with an emphasis on the Si effects. An appropriate Si content in the matrix can not only achieve stable and dense films, but also suppress the formation of oxygen vacancies efficiently, due to its high oxygen bonding ability. Thin film transistors (TFTs) with α-SZTO active channel layers exhibited a field-effect mobility of around 1 cm2V−1s−1, an on/off current ratio of 107, and a subthreshold swing of 0.863 V/decade with a good long-term stability. The α-SZTO TFT is a potential candidate for electronic applications.
Polarization-induced enhancement of photoluminescence in Pr3+ doped ferroelectric diphase BaTiO3-CaTiO3 ceramics
Authors: Zou Hua , Peng Dengfeng , Wu Guangheng , Wang Xusheng , Bao Dinghua , Li Jun , Li Yanxia , Yao Xi
Published: August 2013

Photoluminescence (PL) spectra impacted by electric polarization in Pr3+ doped diphase (1-x)BaTiO3-xCaTiO3 (x = 0.4–0.7) ceramics were studied systematically. The transparent electrode of indium tin oxide was deposited on both surfaces of ceramics to reduce experimental errors and then PL properties were characterized with and without polarization. An enhancement in PL intensity of ∼100% was obtained in the Ba1−xCaxTiO3 (x = 0.7) ceramics with polarization. It was found that the PL intensity increased the same level whether the poling direction was up or down. With the x increases, the enhanced factor decreased first and then increased, which ascribed to the ratio of the tetragonal Ba0.77Ca0.23TiO3 and orthorhombic Ba0.1Ca0.9TiO3 in the diphase ceramics. The investigation of UV-Vis reflective spectrum and X-ray Photoelectron Spectroscopy spectrum demonstrated that the polarization effect on the PL was attributed to the change of band gap of host by a local electric field around Pr3+ doped in Ba0.1Ca0.9TiO3. The local electric field was supposed to be produced by the remanent polarization from ferroelectric Ba0.77Ca0.23TiO3 matrix. The band gap of the host became smaller in the polarized sample, which suggests that an increase in the band gap excitation of the host, i.e., increasing the PL intensity.
Enhanced photoluminescence from zinc oxide by plasmonic resonance of reduced graphene oxide
Authors: Kim Kukjoo , Min Lee Seong , Seon Do Yun , Il Ahn Sung , Cheol Choi Kyung
Published: August 2013

We demonstrate 2.79- and 10.16-fold enhanced photoluminescence (PL) from band-edge and defect levels of zinc oxide (ZnO) using a plasmonic resonance of reduced graphene oxide (RGO) in the UV frequency range. RGO shows superior tunability on the light absorption of ZnO by the confined plasmonic resonance, which results in strong PL emission. We conclude that the absorption of ZnO in close proximity to the RGO layer can be enhanced. These arguments are strongly supported by different PL enhancements depending on the distance between RGO and ZnO layers, time-resolved PL, and numerical calculations.
Disparate effects of an O2 internal impurity on the elongation and quantum transport of gold and silver nanowires
Authors: Barzilai S. , Tavazza F. , Levine L. E.
Published: August 2013

In this work, we investigated the effects of an internal O2 impurity on the conductance of elongated gold and silver nanowires (NWs) using density functional theory calculations. We found that the O2 interacts with these metallic NWs very differently. In the case of gold NWs, the presence of an internal oxygen molecule locally strengthens the wire, therefore, forcing the phase transformations connected to the thinning process (3D to 2D and 2D to single atom chain) to occur far from the oxygen. As a consequence, towards the end of the elongation, the internal O2 is located far from the main conductance channel and therefore has little influence on the conductance of the NW. In contrast, in silver NWs, the presence of an internal oxygen molecule involves a larger charge transfer from the metallic atoms to the oxygen, therefore, weakening the Ag-Ag binding. During the initial stages of the elongation, several metallic bonds adjacent to the impurity break, so that in most simulations the NW thinning takes place near the O2. This thinning mechanism places the O2 near the main conductance channel, therefore, significantly reducing the conductivity of the elongated silver NWs. For both metals, our findings agree well with the published experimental results.
Critical size for the generation of misfit dislocations and their effects on electronic properties in GaAs nanosheets on Si substrate
Authors: Yuan Zaoshi , Shimamura Kohei , Shimojo Fuyuki , Nakano Aiichiro
Published: August 2013

While nanowires and nanosheets (NSs) grown on lattice-mismatched substrates have a number of promising technological applications such as solar cells, generation of misfit dislocations (MFDs) at their interfaces is a major concern for the efficiency of these devices. Here, combined molecular-dynamics and quantum-mechanical simulations are used to study MFDs at the interface between a GaAs NS and a Si substrate. Simulation results show the existence of a critical NS thickness, below which NSs are grown free of MFDs. The calculated critical thickness value is consistent with available experimental observations. Charge transfer at the MFD core is found to modify the electronic band profile at the GaAs/Si interface significantly. These effects should have profound impacts on the efficiency of lattice-mismatched NS devices.
Origin of temperature independent piezoelectric coefficient in Pb(Mg1/3Nb2/3)O3-BaTiO3-PbTiO3 ceramics
Authors: Huang Lizhu , Bulou Alain , Kassiba Abdelhadi , Zeng Jiangtao , Fu Desheng , Errien Nicolas , Zheng Liaoying , Li Guorong
Published: August 2013

The temperature dependence of piezoelectric resonance frequency, dielectric, and piezoelectric properties of (65-x)[Pb(Mg1/3Nb2/3)O3]–xBaTiO3-35PbTiO3 (x = 0, 1, 2, 3) ceramics has been investigated. Sample compositions with x = 2 and 3 were found to exhibit a large piezoelectric response. Particularly, d31 value was nearly a constant over a temperature range from 150 to 325 K. A broad ferroelectric phase transition tuned by BaTiO3 ratio in the sample was deduced from the dielectric constant, piezoelectric resonance frequency, and Raman spectra. The temperature dependence of the Raman modes wavenumber positions and intensities provides a clear evidence for the occurrence of the phase transition. The temperature-stable piezoelectric response was attributed to the counter-balance of contributions from the dielectric and elastic responses.
Note: A transient absorption spectrometer using an ultra bright laser-driven light source
Authors: Su Man-Nung , Jr-Min Lin Jim
Published: August 2013

An apparatus to measure transient absorption spectra for short-lived species in the gas phase was built. This was achieved by coupling a laser-driven plasma light source to a time-gated intensified-CCD spectrometer. Although the laser-driven light source features high brightness, ultra broad bandwidth and long lifetime, we found it possesses a plasma oscillation at a frequency of ∼200 kHz with a peak-to-peak amplitude of ∼7%. This oscillation caused significant variation of the baseline of the transient absorption spectra even after averaging. To reduce this problem, we synchronized the detector gate time with the phase of the plasma oscillation. This arrangement results in much greater stability of the spectral baseline. We have tested the performance of the whole system with the time-resolved absorption spectra of excited NO3 radicals produced by pulsed laser photolysis of N2O5.
Doubly excited P-wave resonance states of H− in Debye plasmas
Authors: Jiao L. G. , Ho Y. K.
Published: August 2013

We investigate the doubly excited P-wave resonance states of H− system in Debye plasmas modeled by static screened Coulomb potentials. The screening effects of the plasma environment on resonance parameters (energy and width) are investigated by employing the complex-scaling method with Hylleraas-type wave functions for both the shape and Feshbach resonances associated with the H(N = 2 to 6) thresholds. Under the screening conditions, the H(N) threshold states are no longer l degenerate, and all the H− resonance energy levels are shifted away from their unscreened values toward the continuum. The influence of Debye plasmas on resonance widths has also been investigated. The shape resonance widths are broadened with increasing plasma screening strength, whereas the Feshbach resonance widths would generally decrease. Our results associated with the H(N = 2) and H(N = 3) thresholds are compared with others in the literature.
Ferrimagnetism up to 200 K in Ti-rich double perovskites ACu3Ti4−xMnxO12: Role of double exchange mechanism
Authors: Motin Seikh Md , Caignaert V. , Pralong V. , Raveau B.
Published: August 2013

We report the striking switching of the antiferromagnetic ground state of copper-based double perovskites (Ca/La2/3)Cu3Ti4O12 to the ferrimagnetic state by introduction of small amounts of Mn on Ti-sites. CaCu3Ti3MnO12, La2/3Cu3Ti3.5Mn0.5O12, LaCu3Ti3MnO12, and LaCu3Ti2Mn2O12 were synthesized at normal pressure. These Ti-rich oxides are ferrimagnetic despite their strong magnetic dilution. The 200 K ferrimagnet LaCu3Ti2Mn2O12 exhibits intrinsic magnetoresistance, maximum at TC, which is unique in all the series of double distorted perovskites actually known. These properties are discussed in terms of strong antiferromagnetic superexchange Cu–O–Mn interactions. The role of double exchange in the properties of the mixed valent oxide LaCu3Ti2Mn2O12 is discussed.
Photon management with nanostructures on concentrator solar cells
Authors: Buencuerpo J. , Llorens J. M. , Dotor M. L. , Ripalda J. M.
Published: August 2013

Optimizing the feature sizes of dielectric nanostructures on the top (ZnS) and bottom (SiO2) surfaces of a 1 μm thick GaAs solar cell, we obtain a higher efficiency (34.4%) than a similar cell with a state of the art bilayer antireflection coating and a planar mirror (33.2%). The back side nanostructure increases the photocurrent due to enhanced optical path length inside the semiconductor, while the nanostructure on the front side increases the photocurrent due to lower reflectance losses.
Understanding of interface structures and reaction mechanisms induced by Ge or GeO diffusion in Al2O3/Ge structure
Authors: Shibayama Shigehisa , Kato Kimihiko , Sakashita Mitsuo , Takeuchi Wakana , Taoka Noriyuki , Nakatsuka Osamu , Zaima Shigeaki
Published: August 2013

The reaction mechanisms at Al2O3/Ge interfaces with thermal oxidation through the Al2O3 layer have been investigated. X-ray photoelectron spectroscopy reveals that an Al6Ge2O13 layer is formed near the interface, and a GeO2 layer is formed on the Al2O3 surface, suggesting Ge or GeO diffusion from the Ge surface. It is also clarified that the Al6Ge2O13 layer is formed by the different mechanism with a small activation energy of 0.2 eV, compared with the GeO2 formation limited by oxygen diffusion. Formation of Al-O-Ge bonds due to the AlGeO formation could lead appropriate interface structures with high interface qualities.
Indium-tin-oxide clad blue and true green semipolar InGaN/GaN laser diodes
Authors: Hardy Matthew T. , Holder Casey O. , Feezell Daniel F. , Nakamura Shuji , Speck James S. , Cohen Daniel A. , DenBaars Steven P.
Published: August 2013

Replacing a portion of the upper III-nitride cladding with indium-tin-oxide (ITO) has several potential advantages for GaN-based laser diodes (LDs). For green LDs, use of ITO in the waveguide structure reduces the epitaxial p-cladding thickness and growth time, which in turn may reduce thermal damage to the active region. We design ITO-clad blue and green semipolar (202¯1) LDs using asymmetric InGaN waveguiding layers to center the mode on the active region. Lasing is demonstrated at 471 nm with threshold current density of 6.2 kA/cm2 for a device with 200 nm p-GaN and at 518 nm for a device with only 300 nm of p-GaN.
High aspect ratio β-MnO2 nanowires and sensor performance for explosive gases
Authors: Xiao J. , Liu P. , Liang Y. , Li H. B. , Yang G. W.
Published: August 2013

High aspect ratio β-MnO2 nanowires have been synthesized based on a facile and green technique without any chemical additive. The precursor solution of Mn3O4 nanocrystals was first synthesized by laser ablation of a manganese target in deionized water. Due to the high reactive and fresh surface of Mn3O4 nanocrystals produced by laser ablation in liquid, these nanocrystals were spontaneously assembled into the γ-MnOOH nanowires in the precursor solution after aging at room temperature. The high aspect ratio β-MnO2 nanowires were finally produced by the γ-MnOOH nanowires annealing at 300 °C for 3 h. For the high aspect ratio β-MnO2 nanowires, the high specific surface area is advantaged for gas absorption and the unique tunnel structure is good for gas molecule trapping. A gas sensor was made from the β-MnO2 nanowires for explosive gases. The investigations were carried out for the detection of various concentration of H2 at different temperatures, and the results demonstrated that the fabricated gas sensor can detect H2 down to 20 ppm with the sensitivity of 0.5 at 300 °C and short response time of 10s. For sensing CO and ethanol, the detecting concentration reached to 20 ppm at an operation temperature of 150 and 250 °C, respectively. These results can be comparable to that of the current advanced gas sensors made from metal oxide such as ZnO and SnO2, which showing that high aspect ratio β-MnO2 nanowires can be regarded as desirable candidate materials for fabricating gas sensors.
Organic memory device with self-assembly monolayered aptamer conjugated nanoparticles
Authors: Oh Sewook , Kim Minkeun , Kim Yejin , Jung Hunsang , Yoon Tae-Sik , Choi Young-Jin , Jung Kang Chi , Moon Myeong-Ju , Jeong Yong-Yeon , Park In-Kyu , Ho Lee Hyun
Published: August 2013

An organic memory structure using monolayered aptamer conjugated gold nanoparticles (Au NPs) as charge storage nodes was demonstrated. Metal-pentacene-insulator-semiconductor device was adopted for the non-volatile memory effect through self assembly monolayer of A10-aptamer conjugated Au NPs, which was formed on functionalized insulator surface with prostate-specific membrane antigen protein. The capacitance versus voltage (C-V) curves obtained for the monolayered Au NPs capacitor exhibited substantial flat-band voltage shift (ΔVFB) or memory window of 3.76 V under (+/-)7 V voltage sweep. The memory device format can be potentially expanded to a highly specific capacitive sensor for the aptamer-specific biomolecule detection.
Examining the Impact of Urban Morphology on Bicycle Mode Choice
Authors: Rybarczyk Greg , Wu Changshan
Published: August 2013

Nonmotorized transport modes such as bicycling are becoming important components to urban transportation systems in the United States, in particular with the recent emphases on sustainable urban development. Recent bicycle forecasting methods have included urban design elements to help explain bicycle behavior but most measures lack accountability of microscale built form attributes that address bicyclist perception. This study developed a discrete choice model to examine the impact of urban morphological factors on people's utilitarian bicycle mode choice decisions. In the model, traditional factors considered include personal, household, and environmental variables. Urban morphology variables from space syntax were also incorporated in the model to test for the marginal influence of microscale design and space characteristics in the decision to bicycle. Results indicate that microscale built form factors that enhance visibility and contain well connected street networks significantly affected bicycle mode choice decisions at the trip origin. The finding that built form variables by and large influence the probability that someone will commute via bicycle suggests that policies and planning efforts aimed at increasing bicycle mode share should include human-scaled built form metrics that address urban space and cognition.
Concern and Confidence. Architects Making Sense of Climate Adaptation
Authors: Tøsse Sunniva Eikeland
Published: August 2013

Drawing on the analytical concept of ‘sensemaking’ as defined by Weick [1995, Sensemaking in Organizations (Sage, Thousand Oaks, CA)], and on scholarship concerning discourses on architect identity and the regulatory context of architecture, in this paper I examine how architects make sense of the issue of climate adaptation. I found that discourses on architects' identity and context appeared to shape the way climate adaptation was made sense of, rather than the other way around. Also, architect identity and contextual factors were more important in architects' sensemaking than features of the climate adaptation issue itself. Most important among the identity-related element of architects' sensemaking was the conception of architects' expertise as holistic—encompassing both aesthetic–creative and technical–craft-related dimensions. Among contextual factors in architects' sensemaking, national building regulations and the industry's focus on cost efficiency were the most central.
Adaptation to Climate Change in the Private and the Third Sector: Case Study of Governance of the Helsinki Metropolitan Region
Authors: Juhola Sirkku
Published: August 2013

Cities and metropolitan regions are increasingly becoming key locations within which adaptation to climate change is taking place. New modes of governance arrangements are also emerging in cities, and these enable new actors to engage in decision making. In this paper I discuss governance of adaptation in Helsinki. On the basis of empirical data from the private and the third sector, I show how the governance of adaptation is organised within the metropolitan region and, more specifically, what policy instruments are used and what objectives these measures have. The findings suggest that whilst challenges of vertical governance of adaptation remain, there are also challenges in terms of horizontal governance of adaptation.
DNA barcoding of Greenideinae (Hemiptera : Aphididae) with resolving taxonomy problems
Authors: Liu Qing-Hua , Jiang Li-Yun , Qiao Ge-Xia
Published: August 2013

Species of the Greenideinae are distributed mainly throughout South-east Asia and include some important agricultural and horticultural pests. Rapid and accurate species circumscription and identification in this subfamily are very difficult because similar morphological traits are shared among congeneric species. Here, we test the efficiency of DNA barcoding in the Greenideinae by analysing 214 samples covering 42 species belonging to nine genera using two mitochondrial gene fragments (COI barcode fragment and Cytb gene fragment). The results show that DNA barcoding is a useful species identification method in this subfamily. Both genes can correctly identify most species using neighbour-joining tree analyses and distance-based analyses. Based on the molecular and morphological evidence, we question the validity of two species, Mollitrichosiphum rhusae Ghosh, 1917 and Schoutedenia emblica (Patel & Kulkarni, 1953). Further analysis of the COI barcode fragment shows that Greenidea psidii van der Goot, 1917, an invasive species in Hawaii, is possibly from China. This is a preliminary DNA barcoding study in Greenideinae, and comprehensive sampling is needed to rigorously test the usefulness of DNA barcoding in this subfamily.
Non-occupational HIV post-exposure prophylaxis at a Sydney metropolitan sexual health clinic
Authors: Gulholm Trine , Jamani Salina , Poynten I. Mary , Templeton David J.
Published: August 2013

Background Non-occupational HIV post-exposure prophylaxis (NPEP) is prescribed following a risk exposure in an effort to reduce the risk of HIV seroconversion. We aimed to describe the prescribing practices of NPEP at RPA Sexual Health in Sydney, the prevalence and correlates of adverse events (AEs), and factors associated with completing the 28-day course. Methods: The study population included individuals prescribed NPEP during January 2008–December 2011. Correlates of AEs and course completion were assessed by logistic regression. Results: On 319 occasions during the study period, 282 individuals presented for NPEP. Over 90% of presentations followed unprotected anal intercourse between men, mostly receptive (63.6%). Tenofovir–emtricitabine–stavudine (n = 149; 46.7%) and tenofovir–emtricitabine (n = 136; 42.6%) were most commonly prescribed. AEs were reported at 101 presentations (31.7%, 95% confidence interval (CI): 26.6–37.1%), with nausea and lethargy/malaise being the most common. Younger age (P for trend = 0.032), earlier year of NPEP prescription (P for trend = 0.011), being prescribed a regimen other than tenofovir–emtricitabine (P = 0.026), changing the NPEP regimen (P < 0.001) and known completion of the course (P = 0.005) were independently associated with AEs. The course was completed in 228 presentations (71.5%, 95% CI: 66.2–76.4%). Completion was associated with reporting AEs (P = 0.007) and changing regimen (P = 0.001). No documented NPEP failures were identified, although two recipients subsequently seroconverted to HIV due to ongoing high-risk behaviour. Conclusions: NPEP is appropriately targeted to the highest risk HIV exposures at our clinic. Active recall may improve follow-up rates in NPEP recipients.
Climate change and associated fire potential for the south-eastern United States in the 21st century
Authors: Bedel Anthony P. , Mote Thomas L. , Goodrick Scott L.
Published: August 2013

Climate models indicate that the climate of the south-eastern US will experience increasing temperatures and associated evapotranspiration in the 21st century. The current study found that conditions in the south-eastern US will likely become drier overall, given a warmer environment during future winter and spring seasons. This study examined the potential effects of a warmer climate in the 21st century on relevant meteorological fire parameters (e.g. total and convective precipitation, 500-hPa geopotential heights, near-surface relative humidity) and popular fire indices (e.g. Haines and Keetch–Byram Drought Indices) in the south-eastern US. Although the results offered conflicting implications in portions of the study domain, the southern half of the south-eastern US (including the Deep South, the southern Piedmont and Florida) exhibited the highest potential for increasing fire activity in the mid-21st century, given maximum warming and drying in these areas, especially in the spring season.
Blockade of A
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+
tumors
Authors: Beavis Paul A. , Divisekera Upulie , Paget Christophe , Chow Melvyn T. , John Liza B. , Devaud Christel , Dwyer Karen , Stagg John , Smyth Mark J. , Darcy Phillip K.
Published: August 2013

CD73 inhibits antitumor immunity through the activation of adenosine receptors expressed on multiple immune subsets. CD73 also enhances tumor metastasis, although the nature of the immune subsets and adenosine receptor subtypes involved in this process are largely unknown. In this study, we revealed that A
2A
/A
2B
receptor antagonists were effective in reducing the metastasis of tumors expressing CD73 endogenously (4T1.2 breast tumors) and when CD73 was ectopically expressed (B16F10 melanoma). A
2A
−/−
mice were strongly protected against tumor metastasis, indicating that host A
2A
receptors enhanced tumor metastasis. A
2A
blockade enhanced natural killer (NK) cell maturation and cytotoxic function in vitro, reduced metastasis in a perforin-dependent manner, and enhanced NK cell expression of granzyme B in vivo, strongly suggesting that the antimetastatic effect of A
2A
blockade was due to enhanced NK cell function. Interestingly, A
2B
blockade had no effect on NK cell cytotoxicity, indicating that an NK cell-independent mechanism also contributed to the increased metastasis of CD73
+
tumors. Our results thus revealed that CD73 promotes tumor metastasis through multiple mechanisms, including suppression of NK cell function. Furthermore, our data strongly suggest that A
2A
or A
2B
antagonists may be useful for the treatment of metastatic disease. Overall, our study has potential therapeutic implications given that A
2A
/A
2B
receptor antagonists have already entered clinical trials in other therapeutic settings.
A-clustering: a novel method for the detection of co-regulated methylation regions, and regions associated with exposure
Authors: Sofer Tamar , Schifano Elizabeth D. , Hoppin Jane A. , Hou Lifang , Baccarelli Andrea A.
Published: August 2013

Motivation: DNA methylation is a heritable modifiable chemical process that affects gene transcription and is associated with other molecular markers (e.g. gene expression) and biomarkers (e.g. cancer or other diseases). Current technology measures methylation in hundred of thousands, or millions of CpG sites throughout the genome. It is evident that neighboring CpG sites are often highly correlated with each other, and current literature suggests that clusters of adjacent CpG sites are co-regulated.

Results: We develop the Adjacent Site Clustering (A-clustering) algorithm to detect sets of neighboring CpG sites that are correlated with each other. To detect methylation regions associated with exposure, we propose an analysis pipeline for high-dimensional methylation data in which CpG sites within regions identified by A-clustering are modeled as multivariate responses to environmental exposure using a generalized estimating equation approach that assumes exposure equally affects all sites in the cluster. We develop a correlation preserving simulation scheme, and study the proposed methodology via simulations. We study the clusters detected by the algorithm on high dimensional dataset of peripheral blood methylation of pesticide applicators.

Availability: We provide the R package Aclust that efficiently implements the A-clustering and the analysis pipeline, and produces analysis reports. The package is found on http://www.hsph.harvard.edu/tamar-sofer/packages/

Contact: tsofer@hsph.harvard.edu

Supplementary information: Supplementary data are available at Bioinformatics online.
Can stock–recruitment points determine which spawning potential ratio is the best proxy for maximum sustainable yield reference points?
Authors: Legault Christopher M. , Brooks Elizabeth N.
Published: August 2013

Legault, C. M., and Brooks, E. N. 2013. Can stock–recruitment points determine which spawning potential ratio is the best proxy for maximum sustainable yield reference points? – ICES Journal of Marine Science, 70: 1075–1080. The approach of examining scatter plots of stock–recruitment (S–R) estimates to determine appropriate spawning potential ratio (SPR)-based proxies for FMSY was investigated through simulation. As originally proposed, the approach assumed that points above a replacement line indicate year classes that produced a surplus of spawners, while points below that line failed to achieve replacement. In practice, this has been implemented by determining Fmed, the fishing mortality rate that produces a replacement line with 50% of the points above and 50% below the line. A new variation on this approach suggests FMSY proxies can be determined by examining the distribution of S–R points that are above or below replacement lines associated with specific SPRs. Through both analytical calculations and stochastic results, we demonstrate that this approach is fundamentally flawed and that in some cases the inference is diametrically opposed to the method's intended purpose. We reject this approach as a tool for determining FMSY proxies. We recommend that the current proxy of F40% be maintained as appropriate for a typical groundfish life history.
A red herring from the Öresund (ICES40G2): the apparent recovery of the Large Fish Indicator (LFI) in the North Sea hides a non-trawled area
Authors: Sundelöf Andreas , Wennhage Håkan , Svedäng Henrik
Published: August 2013

Sundelöf, A., Wennhage, H., and Svedäng, H. 2013. A red herring from the Öresund (ICES40G2): the apparent recovery of the Large Fish Indicator (LFI) in the North Sea hides a non-trawled area. – ICES Journal of Marine Science, 70: 1081–1084. As reported in a number of previous papers in this journal, the Large Fish Indicator (LFI) was developed for the North Sea. ICES Statistical Rectangle 40G2 was accidentally included in the North Sea calculations of LFI for 2004, 2007 and 2008. This inclusion significantly increased the LFI and was subsequently removed from the analysis. We identify and discuss three reasons to revisit rectangle 40G2 when considering LFI for the North Sea: (i) according to the Marine Strategy Framework Directive (MSFD), the area belongs to the North Sea, (ii) it is a geographically well-defined area where technical regulations have prevented the use of trawls since the 1930s, and (iii) there is evidence of a productive and rather closed cod (Gadus morhua) subpopulation unit in the area, which is an important species for the North Sea LFI.
Marine litter within the European Marine Strategy Framework Directive
Authors: Galgani F. , Hanke G. , Werner S. , De Vrees L.
Published: August 2013

Galgani, F., Hanke, G., Werner, S., and De Vrees, L. 2013. Marine litter within the European Marine Strategy Framework Directive. – ICES Journal of Marine Science, 70: 1055–1064. There have been numerous anthropogenic-driven changes to our planet in the last half-century. One of the most evident changes is the ubiquity and abundance of litter in the marine environment. The EU Marine Strategy Framework Directive (MSFD, 2008/56/EC) establishes a framework within which EU Member States shall take action to achieve or maintain good environmental status (GES) of their marine waters by 2020. GES is based on 11 qualitative descriptors as listed in Annex I of the MSFD. Descriptor 10 (D 10) concerns marine litter. As a follow-up to the related Commission Decision on criteria and methodological standards (2010/477/EU) in which 56 indicators for the achievement of GES are proposed, the EC Directorate-General for the Environment, on the request of the European Marine Directors, established a Technical Subgroup on Marine Litter (TSG ML) under the Working Group on GES. The role of TSG ML is to support Member States through providing scientific and technical background for the implementation of MSFD requirements with regard to D 10. Started in 2011, TSG ML provides technical recommendations for the implementation of the MSFD requirements for marine litter. It summarizes the available information on monitoring approaches and considers how GES and environmental targets could be defined with the aim of preventing further inputs of litter to, and reducing its total amount in, the marine environment. It also identifies research needs, priorities and strategies in support of the implementation of D 10. The work of TSG ML also focuses on the specification of monitoring methods through the development of monitoring protocols for litter in the different marine compartments, and for microplastics and litter in biota. Further consideration is being given to monitoring strategies in general and associated costs. Other priorities include the identification of sources of marine litter and a better understanding of the harm caused by marine litter.
Movement ofPhytophthoraspp. in Maryland's Nursery Trade
Authors: Bienapfl J. C. , Balci Y.
Published: August 2013

Phytophthora spp. cause major losses in the nursery industry worldwide. However, a clear demonstration of the route of movement has not been previously shown. A survey of 10 Maryland nurseries was conducted over a 3-year period to investigate the presence of Phytophthora spp. on newly arrived plants, mainly from West Coast suppliers. Local nursery plants, irrigation water, and potting media were also sampled for Phytophthora spp. Isolates were identified using a combination of morphological characteristics and DNA sequencing. Species identified included Phytophthora cactorum, P. cambivora, P. cinnamomi, P. citrophthora, P. drechsleri, P. elongata, P. gonapodyides, P. hydropathica, P. irrigata, P. lacustris, P. multivora, P. nicotianae, P. pini, P. plurivora, and P. syringae. P. taxon pgchlamydo was also isolated from irrigation water. Eight of the abovementioned Phytophthora spp. were isolated in association with incoming material, indicating that the movement of these pathogens continues to occur. Asymptomatic plant material was the main route of introduction of Phytophthora spp. to Maryland nurseries. Results also indicated that several Phytophthora spp. could be found in Maryland nurseries in association with infested potting media of asymptomatic plants. Although P. ramorum was not detected, our surveys underscore the significance of nursery practices that allow introductions of these significant plant pathogens to new geographic locations.
Management Guidelines of Eosinophilic Esophagitis in Childhood
Authors: Papadopoulou A. , Koletzko S. , Heuschkel R. , Dias J.A. , Allen K.J. , Murch S.H. , Chong S. , Gottrand F. , Husby S. , Lionetti P. , Mearin M.L. , Ruemmele F.M. , Schäppi M.G. , Staiano A. , Wilschanski M. , Vandenplas Y. ,   ESPGHAN Eosinophilic Esophagitis Working Group and the Gastroenterology Committee
Published: August 2013

Objectives:

Eosinophilic esophagitis (EoE) represents a chronic, immune/antigen‐mediated esophageal disease characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil‐predominant inflammation. With few exceptions, 15 eosinophils per high‐power field (peak value) in ≥1 biopsy specimens are considered a minimum threshold for a diagnosis of EoE. The disease is restricted to the esophagus, and other causes of esophageal eosinophilia should be excluded, specifically proton pump inhibitor–responsive esophageal eosinophilia. This position paper aims at providing practical guidelines for the management of children and adolescents with EoE.

Methods:

Relevant literature from searches of PubMed, CINAHL, and recent guidelines was reviewed. In the absence of an evidence base, recommendations reflect the expert opinion of the authors. Final consensus was obtained during 3 face‐to‐face meetings of the Gastroenterology Committee and 1 teleconference.

Results:

The cornerstone of treatment is an elimination diet (targeted or empiric elimination diet, amino acid–based formula) and/or swallowed, topical corticosteroids. Systemic corticosteroids are reserved for severe symptoms requiring rapid relief or where other treatments have failed. Esophageal dilatation is an option in children with EoE who have esophageal stenosis unresponsive to drug therapy. Maintenance treatment may be required in case of frequent relapse, although an optimal regimen still needs to be determined.

Conclusions:

EoE is a chronic, relapsing inflammatory disease with largely unquantified long‐term consequences. Investigations and treatment are tailored to the individual and must not create more morbidity for the patient and family than the disease itself. Better maintenance treatment as well as biomarkers for assessing treatment response and predicting long‐term complications is urgently needed.