bluuebunny/crossref_metadata_2025 huggingface dataset:
Driven transport of particles in 3D ordered porous media
Authors: Chen Shing Bor
Published: August 2013

Brownian dynamics simulation has been employed to study the behavior of force-driven particle transport in two different types of ordered porous media: (A) interconnected spherical cavities and (B) an array of spherical obstacles, both arranged in simple cubic lattice. The effects of the imposed field strength and direction on the particle mobility and diffusivity are investigated. At a given porosity and imposed field strength, the particle mobility is greater for Case B than for Case A, owing to a higher degree of pore openness for the former. While the normalized mobility always increases with the field strength for Case B, irrespective of the field direction, it decreases for Case A when the field is not aligned with an aperture line. The particle diffusion may become anisotropic and show a nonmonotonic behavior with varying field strength. The diffusivity may increase 10-fold under a field misaligned with an aperture line.
Electron dynamics of molecular double ionization by circularly polarized laser pulses
Authors: Tong Aihong , Zhou Yueming , Huang Cheng , Lu Peixiang
Published: August 2013

Using the classical ensemble method, we have investigated double ionization (DI) of diatomic molecules driven by circularly polarized laser pulses with different internuclear distances (R). The results show that the DI mechanism changes from sequential double ionization (SDI) to nonsequential double ionization (NSDI) as the internuclear distance increases. In SDI range, the structure of the electron momentum distribution changes seriously as R increases, which indicates the sensitive dependence of the release times of the two electrons on R. For NSDI, because of the circular polarization, the ionization of the second electron is not through the well-known recollision process but through a process where the first electron ionizes over the inner potential barrier of the molecule, moves directly towards the other nucleus, and kicks out the second electron.
Generalized iterative annealing model for the action of RNA chaperones
Authors: Hyeon Changbong , Thirumalai D.
Published: August 2013

As a consequence of the rugged landscape of RNA molecules their folding is described by the kinetic partitioning mechanism according to which only a small fraction (ϕF) reaches the folded state while the remaining fraction of molecules is kinetically trapped in misfolded intermediates. The transition from the misfolded states to the native state can far exceed biologically relevant time. Thus, RNA folding in vivo is often aided by protein cofactors, called RNA chaperones, that can rescue RNAs from a multitude of misfolded structures. We consider two models, based on chemical kinetics and chemical master equation, for describing assisted folding. In the passive model, applicable for class I substrates, transient interactions of misfolded structures with RNA chaperones alone are sufficient to destabilize the misfolded structures, thus entropically lowering the barrier to folding. For this mechanism to be efficient the intermediate ribonucleoprotein complex between collapsed RNA and protein cofactor should have optimal stability. We also introduce an active model (suitable for stringent substrates with small ϕF), which accounts for the recent experimental findings on the action of CYT-19 on the group I intron ribozyme, showing that RNA chaperones do not discriminate between the misfolded and the native states. In the active model, the RNA chaperone system utilizes chemical energy of adenosine triphosphate hydrolysis to repeatedly bind and release misfolded and folded RNAs, resulting in substantial increase of yield of the native state. The theory outlined here shows, in accord with experiments, that in the steady state the native state does not form with unit probability.
Dynamic dipole polarizabilities of H− and Ps− in weakly coupled plasmas
Authors: Kar Sabyasachi , Li H. W. , Jiang Pinghui
Published: August 2013

The effects of weakly coupled plasmas on the dynamic dipole polarizabilities of the H− and Ps− ions are investigated using highly correlated exponential wave functions. The Debye-Hückel shielding approach of plasma modeling is used to represent weakly coupled plasma environments. In free-atomic cases, results obtained from the present study for H− are in agreement with the available calculations and results for Ps− are reported for the first time. Frequency-dependent polarizabilities of H− and Ps− as functions of screening parameter are also presented for the first time.
Space- and time-resolved observation of extreme laser frequency upshifting during ultrafast-ionization
Authors: Giulietti A. , André A. , Dobosz Dufrénoy S. , Giulietti D. , Hosokai T. , Koester P. , Kotaki H. , Labate L. , Levato T. , Nuter R. , Pathak N. C. , Monot P. , Gizzi L. A.
Published: August 2013

A 65-fs, 800-nm, 2-TW laser pulse propagating through a nitrogen gas jet has been experimentally studied by 90° Thomson scattering. Time-integrated spectra of scattered light show unprecedented broadening towards the blue which exceeds 300 nm. Images of the scattering region provide for the first time a space- and time-resolved description of the process leading quite regularly to such a large upshift. The mean shifting rate was as high as δλ/δt ≈ 3 Å/fs, never observed before. Interferometry shows that it occurs after partial laser defocusing. Numerical simulations prove that such an upshift is consistent with a laser-gas late interaction, when laser intensity has decreased well below relativistic values (a0 ≪ 1) and ionization process involves most of the laser pulse. This kind of interaction makes spectral tuning of ultrashort intense laser pulses possible in a large spectral range.
InGaN/GaN quantum dots as optical probes for the electric field at the GaN/electrolyte interface
Authors: Teubert J. , Koslowski S. , Lippert S. , Schäfer M. , Wallys J. , Dimitrakopulos G. , Kehagias Th. , Komninou Ph. , Das A. , Monroy E. , Eickhoff M.
Published: August 2013

We investigated the electric-field dependence of the photoluminescence-emission properties of InGaN/GaN quantum dot multilayers in contact with an electrolyte. Controlled variations of the surface potential were achieved by the application of external electric fields using the electrolytic Schottky contact and by variation of the solution's pH value. Prior to characterization, a selective electrochemical passivation process was required to suppress leakage currents. The quantum dot luminescence is strongly affected by surface potential variations, i.e., it increases exponentially with cathodic bias and acidic pH values. The results cannot be explained by a modification of intra-dot polarization induced electric fields via the quantum confined Stark effect but are attributed to the suppression/enhancement of non-radiative recombination processes, i.e., mainly hole transfer into the electrolyte. The results establish a link between the photoluminescence intensity and the magnitude of electric fields at the semiconductor/electrolyte interface.
Characterization of intense ion beam energy density and beam induced pressure on the target with acoustic diagnostics
Authors: Pushkarev A. I. , Isakova Yu. I. , Yu Xiao , Khailov I. P.
Published: August 2013

We have developed the acoustic diagnostics based on a piezoelectric transducer for characterization of high-intensity pulsed ion beams. The diagnostics was tested using the TEMP-4M accelerator (150 ns, 250–300 kV). The beam is composed of C+ ions (85%) and protons, the beam energy density is 0.5–5 J/cm2 (depending on diode geometry). A calibration dependence of the signal from a piezoelectric transducer on the ion beam energy density is obtained using thermal imaging diagnostics. It is shown that the acoustic diagnostics allows for measurement of the beam energy density in the range of 0.1–2 J/cm2. The dependence of the beam generated pressure on the input energy density is also determined and compared with the data from literature. The developed acoustic diagnostics do not require sophisticated equipment and can be used for operational control of pulsed ion beam parameters with a repetition rate of 103 pulses/s.
Development of a multiplex stimulated Raman microscope for spectral imaging through multi-channel lock-in detection
Authors: Seto Keisuke , Okuda Yoshinao , Tokunaga Eiji , Kobayashi Takayoshi
Published: August 2013

We report the development of a multiplex stimulated Raman microscope for spectral imaging through multi-channel lock-in detection with a single light source. A white pump beam is prepared with a piece of photonic crystal fiber (PCF). The system does not require the synchronization of plural light sources or the scanning of their wavelengths, and thus a jitter-free pair of pump and Stokes beams is obtained, and a high degree of temporal synchronization is attained in the spectra. The multi-channel lock-in detection (extended to 128 channels) enables the observation of pseudo-continuous stimulated Raman spectra, demonstrating the strong ability of qualitative analysis to identify various types of C–H stretching modes such as the symmetric and asymmetric modes of the methylene/methyl and aromatic groups. Images of a mixed film of polystyrene and polymethylmethacrylate are presented to demonstrate the system's spectral imaging ability. The spatial distribution of these materials is successfully captured through one-time imaging, although the noise of the white light pump beam generated with the PCF limits the system's imaging speed.
Single flux transistor: The controllable interplay of coherent quantum phase slip and flux quantization
Authors: Kafanov S. , Chtchelkatchev N. M.
Published: August 2013

The single Cooper pair josephson transistor is a device that exhibits at the same time charge quantization and phase coherence. Coherent quantum phase slip phenomenon is “dual” the Josephson phase coherence, while the charge quantization is dual to the flux quantization. We present the experimental demonstration and the theoretical description of a new superconducting device–single flux transistor, which is dual to the single Cooper pair transistor. Our transport measurements show the periodic modulation of the critical voltage by the external magnetic field. The obtained current-voltage characteristics show the hysteretic behavior, which we attribute to the intrinsic self-heating of charge carriers.
A general technology adoption model of solar photovoltaic under feed-in tariff policy incorporating learning and network effects
Authors: Shum Kwok L.
Published: August 2013

There is now a plethora of renewable energy policy instruments to support the adoption of renewable energy technology and the generation of renewable electricity. Different ways to characterize such policies have included whether these policies are Price driven or Quota (Quantity) driven, generation based or capacity driven, etc. All such incentive-based policies (vs. Command and control policies) attempt to correct market failure of under supply of renewable energy. This paper uses a technology adoption approach to study the feed-in tariff policy for the photovoltaic (PV) technology. We developed a general economic model to study the adoption incentive for smaller system under a feed-in tariff regime. The model incorporates both the learning effect of system cost and a negative network externality effect inherent in the feed-in tariff policy. The latter is due to that nonadopters would need to contribute to payment for adopters' electricity generation. Using numerical methods, we demonstrated that the feed-in tariff model has the potential to exhibit bandwagon or accelerated adoption effects. Cost learning is key to contributing to this but network effects would serve to dampen it. Our model seems to able to explain the rapid growth pattern in PV systems installation capacity and generation in Germany during the growth period of 1999–2003. We explore some policy implications of the model and suggest future research directions.
Methane activation using noble gases in a dielectric barrier discharge reactor
Authors: Jo Sungkwon , Hoon Lee Dae , Seok Kang Woo , Song Young-Hoon
Published: August 2013

The conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—He, Ne, and Ar—as additives. The empirical results obtained clearly indicate that methane activation is considerably affected by thy type of noble gas used. Through 0-D calculations, the discharge parameters inside the reactor, i.e., electron temperature and electron density, are estimated using experiment results. A comparison of the discharge characteristics and experimental results shows that the electron temperature is an important factor in achieving high methane activation and the mixture with Ar gas shows the highest methane conversion. These results are constructed using the mechanisms of energy and charge transfer from excited and ionized noble gas atoms to methane molecules, considering the number density of active atoms of noble gases. Finally, electron temperatures obtained for gas mixtures having different reactant compositions and concentrations are analyzed to estimate methane activation.
Surface defects induced ferromagnetism in mechanically milled nanocrystalline ZnO
Authors: Ghose Srabantika , Sarkar A. , Chattopadhyay S. , Chakrabarti M. , Das D. , Rakshit T. , Ray S. K. , Jana D.
Published: August 2013

Bulk ZnO is a diamagnetic material but ferromagnetism (FM) has been observed by several groups in its nanostructures. In order to elucidate the room temperature (RT) FM of ZnO nanostructures, magnetic property of mechanically milled and subsequently annealed nano-ZnO powder has been investigated. Sample that has been milled and then annealed at 200 °C in ambient condition shows highest value of saturation magnetization (Ms), whereas lowest value of Ms has been noticed for the sample pre-annealed at 500 °C before milling. The variation of Ms with annealing temperatures closely resembles with the variation of average positron lifetime (τav) and S-parameter reported earlier for these nano-systems. It has also been found that Ms decreases systematically for increasing average grain size of the ZnO nanoparticles. Room temperature photoluminescence of the as-milled sample shows broad defect related emission centered ∼2.23 eV. Enhancement of such emission has been observed due to 200 °C annealing. Results altogether indicate that ferromagnetism in ZnO depends critically on the nature of disorder (open volume defects as well as defect clusters) at the grain surface region. In this connection, the possible role of zinc vacancy defects has also been emphasized.
Quantum effects in electron beam pumped GaAs
Authors: Yahia M. E. , Azzouz I. M. , Moslem W. M.
Published: August 2013

Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.
Study of the mechanism and rate of exciton dissociation at the donor-acceptor interface in bulk-heterojunction organic solar cells
Authors: Rita Narayan Monishka , Singh Jai
Published: August 2013

In this paper, a comprehensive study is carried out on the dissociation mechanism of excitons in bulk-heterojunction organic solar cells. It is proposed that at the donor-acceptor interface, a Frenkel exciton relaxes to a charge transfer exciton and then dissociates into free charge carriers with the aid of molecular vibrational energy. The interaction operator between the charge transfer exciton and molecular vibrational energy is derived and used to formulate and calculate the rates of dissociation of singlet and triplet excitons into free charge carriers. The dissociation rates are found to be dependent on the binding energy, lowest unoccupied molecular orbital offset between the donor and acceptor, the phonon energy, reduced excitonic mass, excitonic Bohr radius, and the dielectric constant of the organic material. Using the proposed dissociation mechanism, three points have also been highlighted that could provide possible reasons as to why the performance of bulk-heterojunction organic solar cell is low.
Tuning the emission colour by manipulating terbium-terbium interactions: Terbium doped aluminum nitride as an example system
Authors: Benz Felix , Strunk Horst P. , Schaab Jakob , Künecke Ulrike , Wellmann Peter
Published: August 2013

Terbium-terbium interactions in terbium doped semiconductors and insulators may lead to the so-called cross-relaxation process, which increases the D54 (green) emission of the terbium ions at the cost of the D53 (blue) luminescence intensity. This effect can generally be reduced by increasing the distance between an excited ion and the nearest ion in the ground state. A straightforward measure is to use a specimen with a decreased terbium concentration. The alternative is to increase the intensity of the excitation (either by photons or electrons) and thereby to reduce the population of terbium ions in the ground state. This paper works this process out with the example of AlN:Tb on the basis of a model and respective experimental results. As will be seen, stronger excitation causes in essence more Tb ions to be excited, thus less ions in the ground state which increases the distance between an excited and the nearest ground state ions. This hinders energy transfer between the terbium ions and thus counteracts the cross-relaxation process. The advantage of changing the excitation intensity lies in the possibility to deliberately shift the apparent colour of the Tb luminescence from a single specimen between green and blue.
Dynamics of laser-blow-off induced Li plume in confined geometry
Authors: Kumar Bhupesh , Singh R K , Kumar Ajai
Published: August 2013

Dynamics of Li plasma plume created by laser-blow-off technique in air ambient is reported. Plasma plume dynamics and its optical emission are investigated in planar and confined geometries using time resolved shadowgraph imaging and optical emission spectroscopy. Significant differences in the plasma characteristics in confined geometry are quantitatively investigated by comparing the plasma parameters (temperature and density) in free expansion and confined geometry configurations. Dynamics and physical parameters of the primary as well as the reflected shock waves (in confined geometry) and their interactions with expanding plasma are briefly addressed. A large enhancement in the emission intensities of Li I 610.3 nm (2p 2P1/2, 3/2 ← 3d 2P3/2, 5/2) and 670.8 nm (2s 2S1/2 ← 2p 2P1/2, 3/2) is correlated with the shock wave dynamics in the two geometries. Strong self reversal in the neutral emission infers an increase in the population density of neutrals within the confined plasma plume.
Estimations of Mo X-pinch plasma parameters on QiangGuang-1 facility by L-shell spectral analyses
Authors: Wu Jian , Li Mo , Li Xingwen , Wang Liangping , Wu Gang , Ning Guo , Qiu Mengtong , Qiu Aici
Published: August 2013

Plasma parameters of molybdenum (Mo) X-pinches on the 1-MA QiangGuang-1 facility were estimated by L-shell spectral analysis. X-ray radiation from X-pinches had a pulsed width of 1 ns, and its spectra in 2–3 keV were measured with a time-integrated X-ray spectrometer. Relative intensities of spectral features were derived by correcting for the spectral sensitivity of the spectrometer. With an open source, atomic code FAC (flexible atomic code), ion structures, and various atomic radiative-collisional rates for O-, F-, Ne-, Na-, Mg-, and Al-like ionization stages were calculated, and synthetic spectra were constructed at given plasma parameters. By fitting the measured spectra with the modeled, Mo X-pinch plasmas on the QiangGuang-1 facility had an electron density of about 1021 cm−3 and the electron temperature of about 1.2 keV.
Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating
Authors: Jin Seo Hyok , Hee Lee Mi , Kwon Byeong-Ju , Kim Hye-Lee , Jin Lee Seung , Kim Bong-Jin , Wang Kang-Kyun , Kim Yong-Rok , Park Jong-Chul
Published: August 2013

Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH2 (399.70 eV) was increased significantly and –N=CH (400.80 eV) and –NH3+ (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.
Enhancement of exchange bias field in top-pinned FeMn/Py bilayers with Ta/Cu hybrid underlayers
Authors: Kim Ki-Yeon , Choi Hyeok-Cheol , Jo Sin-Yong , You Chun-Yeol
Published: August 2013

We compared the exchange bias field Hex of bottom-pinned Py/FeMn and top-pinned FeMn/Py bilayers with Ta/Cu hybrid underlayers for both as-deposited and annealed cases. Top-pinned bilayers show higher Hex than bottom-pinned bilayers. It is more than two times higher than that of bottom-pinned bilayers and even more than one order of magnitude higher than that of top-pinned bilayer with Ta single underlayers. Furthermore, top-pinned bilayers exhibit enhanced Hex after field cooling, while bottom-pinned bilayers remain almost unchanged. Dramatic increase in intensity of FeMn peak due to hybrid underlayer and FeMn/Py interface roughness dominantly result in the enhanced exchange bias field in the as-deposited case. On the other hand, the microstructural change like interface morphology and FeMn chemical composition at FeMn/Py local interface rather than crystallographic texture of FeMn layer play a key role in enhancing the exchange bias field in annealed case. Our results cannot be explained by the results from the previous studies on IrMn/CoFe bilayers. We suggest that the stoichiometric Fe50Mn50 ratio around FeMn/Py interface as well as FeMn(111) texture should be responsible for high Hex of top-pinned bilayers with Ta/Cu hybrid underlayers.
Low temperature nanoscale electronic transport on the MoS2 surface
Authors: Thamankar R. , Yap T. L. , Goh K. E. J. , Troadec C. , Joachim C.
Published: August 2013

Two-probe electronic transport measurements on a Molybdenum Disulphide (MoS2) surface were performed at low temperature (30 K) under ultra-high vacuum conditions. Two scanning tunneling microscope tips were precisely positioned in tunneling contact to measure the surface current-voltage characteristics. The separation between the tips is controllably varied and measured using a high resolution scanning electron microscope. The MoS2 surface shows a surface electronic gap (ES) of 1.4 eV measured at a probe separation of 50 nm. Furthermore, the two- probe resistance measured outside the electronic gap shows 2D-like behavior with the two-probe separation.
Experimental evidence of ultrasonic opacity using the coupling of resonant cavities in a phononic membrane
Authors: Elayouch Aliyasin , Addouche Mahmoud , Herth Etienne , Khelif Abdelkrim
Published: August 2013

We report the practical realization of phononic membrane with sub-wavelength apertures, inducing a broadband ultrasonic opacity. The ultrasonic experiments confirm the existence of deep and wide attenuation in the transmission spectrum, through periodic aperture arrays in silicon substrate immersed in water. This attenuation reaches 30 dB on a relative bandwidth of 31% with a center frequency of 0.9 MHz. The arrays act as Fabry-Perot acoustic resonators, and through the coupling effect between them, we obtain a series of asymmetric shape peaks in the transmission spectra. This leads to an enhanced transmission at the resonance frequencies as well as to improve the attenuation significantly at the antiresonance frequencies.
Communication: Autodetachment versus internal conversion from the S1 state of the isolated GFP chromophore anion
Authors: West Christopher W. , Hudson Alex S. , Cobb Steven L. , Verlet Jan R. R.
Published: August 2013

The anionic form of p-hydroxybenzylidene-2,3-dimethylimidazolinone (HBDI) has been extensively employed as a model of the chromophore of the green fluorescence protein. The bright S1 excited state HBDI− has a measured lifetime of 1.4 ps in the gas-phase and is dominated by two non-radiative decay mechanisms: internal conversion and autodetachment into the neutral continuum. Here, time-resolved photoelectron spectroscopy has been used to determine the yields of these two channels from which the lifetime for autodetachment was found to be ∼30 ps.
Conductive preferential paths of hot carriers in amorphous phase-change materials
Authors: Cappelli Andrea , Piccinini Enrico , Xiong Feng , Behnam Ashkan , Brunetti Rossella , Rudan Massimo , Pop Eric , Jacoboni Carlo
Published: August 2013

We study charge transport properties of amorphous phase-change materials (PCM) using a set of balance equations applied to a three-dimensional random network of sites. In the context of trap-limited conduction, model results are checked against experimental data on PCM devices near the limits of scaling (∼10 nm), explaining the main features of the current-voltage characteristics. The stochastic nature of the network also allows us to investigate the statistical variability of the sub-threshold PCM operation. Simulations of batches of similar samples show a standard deviation for the threshold condition of the order of few percent for the threshold voltage and of ten percent for the threshold current. The analysis of the network at the microscopic level near threshold reveals the formation of high-current paths, connecting the two contacts of the device through network nodes hosting the hottest carriers.
Nonlinear ferromagnetic resonance induced by spin torque in nanoscale magnetic tunnel junctions
Authors: Cheng X. , Katine J. A. , Rowlands G. E. , Krivorotov I. N.
Published: August 2013

Spin transfer torque can excite ferromagnetic resonance of magnetization in a nanoscale magnetic tunnel junction. Here we describe a strongly nonlinear regime of spin-torque-driven ferromagnetic resonance in which large-amplitude magnetization oscillations are excited by microwave current applied to the junction. In this nonlinear regime, the junction generates a large direct voltage in response to the applied microwave signal and thereby can serve as a sensitive microwave signal detector. We demonstrate a low-temperature detector sensitivity of 2.5 × 104 V/W, which exceeds the sensitivity of metal-semiconductor Schottky diodes.
Maximizing performances of variable tilt flat-plate solar collectors for Belgrade (Serbia)
Authors: Skerlić Jasmina , Radulović Jasna , Nikolić Danijela , Bojić Milorad
Published: August 2013

In Serbia, for heating of domestic hot water (DHW) it is customary to use electricity. As around 70% of electricity is produced by using low quality coal with high greenhouse emission, it is beneficial to environment to use solar energy by flat-plate solar collectors for heating of DHW in a solar DHW system (SDHWS). The SDHWS with variable tilt flat-plate solar collectors placed in north-south direction at roofs of houses are investigated for their optimal operation in Belgrade, Serbia. The investigated variable-tilt collectors annually take 2 tilts, 4 tilts, and 12 tilts. The used weather data are from the meteorological station. These investigations use three computer codes: EnergyPlus, GenOpt, and Hooke-Jeeves search algorithm. For different solar collectors, the investigations revile their optimum tilts that maximize the solar fraction by the SDHWS. Then, the solar fraction and avoided fossil energy by the SDHWS are maximized. In addition, the deficit in the solar fraction is estimated when the solar collectors are not at their optimum tilt.
High-performance symmetric electrochemical capacitor based on graphene foam and nanostructured manganese oxide
Authors: Bello Abdulhakeem , Fashedemi Omobosede O. , Lekitima Joel N. , Fabiane Mopeli , Dodoo-Arhin David , Ozoemena Kenneth I. , Gogotsi Yury , Charlie Johnson Alan T. , Manyala Ncholu
Published: August 2013

We have fabricated a symmetric electrochemical capacitor with high energy and power densities based on a composite of graphene foam (GF) with ∼80 wt% of manganese oxide (MnO2) deposited by hydrothermal synthesis. Raman spectroscopy and X-ray diffraction measurements showed the presence of nanocrystalline MnO2 on the GF, while scanning and transmission electron microscopies showed needle-like manganese oxide coated and anchored onto the surface of graphene. Electrochemical measurements of the composite electrode gave a specific capacitance of 240 Fg−1 at a current density of 0.1 Ag−1 for symmetric supercapacitors using a two-electrode configuration. A maximum energy density of 8.3 Whkg−1 was obtained, with power density of 20 kWkg−1 and no capacitance loss after 1000 cycles. GF is an excellent support for pseudo-capacitive oxide materials such as MnO2, and the composite electrode provided a high energy density due to a combination of double-layer and redox capacitance mechanisms.
The dual effects of Al-doping on the ferromagnetism of Zn0.98–yEr0.02AlyO thin films
Authors: Chen Hong-Ming , Liu Xue-Chao , Zhuo Shi-Yi , Xiong Ze , Zhou Ren-Wei , Yang Jian-Hua , Shi Er-Wei
Published: August 2013

Zn0.98–yEr0.02AlyO (0 ≤ y ≤ 0.04) thin films have been prepared by inductively coupled plasma enhanced physical vapor deposition method. It is found that Er3+ substitutes Zn2+ in ZnO lattice without forming any magnetic secondary phase. Al-doping has dual effects on the electron transport and magnetic properties of Er-doped ZnO films, wherein AlZn and Ali play different roles. When 0 ≤ y ≤ 0.02, the dominant AlZn increases and induces both carrier concentration and saturation magnetization (Ms) increasing. When 0.02 < y ≤ 0.04, Ali becomes main defect and enhances the probability of electron scattering, thus reduces the Ms.
Magneto-induced normal stress of magnetorheological plastomer
Authors: Liu Taixiang , Xu Yangguang , Gong Xinglong , Pang Haoming , Xuan Shouhu
Published: August 2013

An abrupt drop phenomenon of magneto-induced normal stress of magnetorheological plastomer is reported and a microstructure dependent slipping hypothesis is proposed to interpret this interesting behavior. For polyurethane based magnetorheological plastomer sample with 70 wt.% carbonyl iron powder, the magneto-induced normal stress can reach to as high as 60.2 kPa when a 930 mT magnetic field is suddenly applied. Meanwhile, the normal stress shows unpredicted abrupt drop. Particle dynamics is used to investigate the physical generating mechanism of normal stress. The simulation result agrees well with the experimental result, indicating that the interior microstructure of iron particle aggregation plays a crucial role to the normal stress.
No More Credit to Europe? Cross-Border Bank Lending, Financial Integration, and the Rebirth of the National Scale as a Credit Scorecard
Authors: Bassens David , van Meeteren Michiel , Derudder Ben , Witlox Frank
Published: August 2013

The Eurozone crisis that erupted in 2008 has raised sincere doubts about the durability of political and financial linkages among its member states. This paper associates the resulting political–economic stasis of the Eurozone with the coevolution of the financial and monetary system at the European scale. The argument builds on insights from financial geography, cultural political economy, and sociology of finance. It focuses on the idea that financial market rationalities, which fluctuate over time and space, are socially constructed through an interplay of acts of ‘bricolage’ by state and market actors. We relate these rationalities to the main European initiatives regarding financial and monetary integration since the 1992 Maastricht Treaty. By tracing the geographical patterns of cross-border lending of European banks in the period 2003–10 we observe that two radically different rationalities of ‘sound investment’ have dominated before and after the crisis. In the precrisis conjuncture of convergence, the Eurozone seemed to develop ‘according to plan’ where the financial system appeared beneficial in terms of equalizing development. However, since the crisis there has been a conjuncture of ‘contagion’ in which country-level specificities increasingly determine creditworthiness. Meanwhile, we observe that European policy makers try to refit the monetary system to this new market rationality to make the European scale ‘perform’ again.
Exhibition Visitors are Sensitive to Patterns of Display Covisibility
Authors: Lu Yi , Peponis John
Published: August 2013

We report a study designed to test whether visitors to virtual exhibition environments are sensitive to patterns of display covisibility. We show that visitors' assessment of the clarity of presentation of a pictorial theme is associated with the degree of covisibility of member works. We also show that visitors are effortlessly able to identify locations and orientations which maximize the covisibility of member works. The analysis involves the refinement of existing measures of the objective covisibility affordances of layouts to take into account orientation, viewing angle, and subtended angle. By showing that exhibition visitors are sensitive to patterns of display covisibility we complement a growing literature which offers assessments of exhibition environments from the point of view of covisibility affordances.
Integrating Climate Change into Governance at the Municipal Scale: An Institutional Perspective on Practices in Denmark
Authors: Wejs Anja
Published: August 2013

Climate change (CC) is a new and, up to 2013, voluntary planning area in Denmark, and it is perceived as an interdisciplinary field affecting several professions. CC is integrated into bureaucratised municipal organisations characterised by a fragmented organisational structure and strong institutional traditions and perceptions. With this paper I examine different approaches to CC governance and the institutional dynamics that occur in the integration process within eight Danish municipalities in the initial phase of integrating CC. The results show three different governance approaches related to CC planning: experimental, negotiation, and standardisation. This paper contributes insights into the intrainstitutional dynamics at the local level when climate plans are to be implemented in practice, and it adds perspectives on the role of local established networks rather than international networks for less affluent municipalities to act on CC.
Home range size and use by the long-nosed bandicoot (Perameles nasuta) following fire
Authors: MacGregor Christopher I. , Wood Jeff T. , Dexter Nick , Lindenmayer David B.
Published: August 2013

Understanding how animals use available habitat and how disturbance events such as fire influence habitat use is crucial to wildlife management. Relationships between home-range size of long-nosed bandicoots (Perameles nasuta) and vegetation type and fire effects on food availability and vegetation cover were explored. Home ranges and movement of P. nasuta were mapped in burnt and unburnt vegetation using radio-tracking. Compositional analysis was used to study their habitat associations. In 2004, six months after wildfire, no significant relationships were found between home-range size and vegetation type. In 2005, there was a preference for dry and wet forest over heath and disturbed areas. In both years, in ranges that contained both burnt and unburnt vegetation, there was a preference for unburnt vegetation. Home-range size was positively related to the bodyweight of individuals. Fire did not significantly alter home-range size, but did influence the way animals used their home range. Dense understorey might provide vital shelter from predators, and may be particularly important after fire. Wildfire and prescribed burning are major forms of disturbance in many natural areas and this study suggests the importance to P. nasuta of retaining unburnt patches when conducting hazard-reduction burning.
Transcriptome profiling of peanut (Arachis hypogaea) gynophores in gravitropic response
Authors: Li Hai-fen , Chen Xiao-Ping , Zhu Fang-he , Liu Hai-Yan , Hong Yan-Bin , Liang Xuan-Qiang
Published: August 2013

Peanut (Arachis hypogaea L.) produces flowers aerially, but the fruit develops underground. This process is mediated by the gynophore, which always grows vertically downwards. The genetic basis underlying gravitropic bending of gynophores is not well understood. To identify genes related to gynophore gravitropism, gene expression profiles of gynophores cultured in vitro with tip pointing upward (gravitropic stimulation sample) and downward (control) at both 6 and 12 h were compared through a high-density peanut microarray. After gravitropic stimulation, there were 174 differentially expressed genes, including 91 upregulated and 83 downregulated genes at 6 h, and 491 differentially expressed genes including 129 upregulated and 362 downregulated genes at 12 h. The differentially expressed genes identified were assigned to 24 functional categories. Twenty pathways including carbon fixation, aminoacyl-tRNA biosynthesis, pentose phosphate pathway, starch and sucrose metabolism were identified. The quantitative real-time PCR analysis was performed for validation of microarray results. Our study paves the way to better understand the molecular mechanisms underlying the peanut gynophore gravitropism.
NR2B subunit of the NMDA glutamate receptor regulates appetite in the parabrachial nucleus
Authors: Wu Qi , Zheng Ruimao , Srisai Dollada , McKnight G. Stanley , Palmiter Richard D.
Published: August 2013

Diphtheria toxin-mediated, acute ablation of hypothalamic neurons expressing agouti-related protein (AgRP) in adult mice leads to anorexia and starvation within 7 d that is caused by hyperactivity of neurons within the parabrachial nucleus (PBN). Because NMDA glutamate receptors are involved in various synaptic plasticity-based behavioral modifications, we hypothesized that modulation of the NR2A and NR2B subunits of the NMDA receptor in PBN neurons could contribute to the anorexia phenotype. We observed by Western blot analyses that ablation of AgRP neurons results in enhanced expression of NR2B. Interestingly, systemic administration of LiCl in a critical time window before AgRP neuron ablation abolished the anorectic response. LiCl treatment suppressed NR2B levels in the PBN and ameliorated the local Fos induction that is associated with anorexia. This protective role of LiCl on feeding was blunted in vagotomized mice. Chronic infusion of RO25-6981, a selective NR2B inhibitor, into the PBN recapitulated the role of LiCl in maintaining feeding after AgRP neuron ablation. We suggest that the accumulation of NR2B subunits in the PBN contributes to aphagia in response to AgRP neuron ablation and may be involved in other forms of anorexia.
fmcsR: mismatch tolerant maximum common substructure searching in R
Authors: Wang Yan , Backman Tyler W. H. , Horan Kevin , Girke Thomas
Published: August 2013

Motivation: The ability to accurately measure structural similarities among small molecules is important for many analysis routines in drug discovery and chemical genomics. Algorithms used for this purpose include fragment-based fingerprint and graph-based maximum common substructure (MCS) methods. MCS approaches provide one of the most accurate similarity measures. However, their rigid matching policies limit them to the identification of perfect MCSs. To eliminate this restriction, we introduce a new mismatch tolerant search method for identifying flexible MCSs (FMCSs) containing a user-definable number of atom and/or bond mismatches.

Results: The fmcsR package provides an R interface, with the time-consuming steps of the FMCS algorithm implemented in C++. It includes utilities for pairwise compound comparisons, structure similarity searching, clustering and visualization of MCSs. In comparison with an existing MCS tool, fmcsR shows better time performance over a wide range of compound sizes. When mismatching of atoms or bonds is turned on, the compute times increase as expected, and the resulting FMCSs are often substantially larger than their strict MCS counterparts. Based on extensive virtual screening (VS) tests, the flexible matching feature enhances the enrichment of active structures at the top of MCS-based similarity search results. With respect to overall and early enrichment performance, FMCS outperforms most of the seven other VS methods considered in these tests.

Availability: fmcsR is freely available for all common operating systems from the Bioconductor site (http://www.bioconductor.org/packages/devel/bioc/html/fmcsR.html).

Contact: thomas.girke@ucr.edu

Supplementary information: Supplementary data are available at Bioinformatics online.
Public perceptions of wetland restoration benefits in Louisiana
Authors: Kim Tae-Goun , Petrolia Daniel R.
Published: August 2013

Kim, T-G., and Petrolia, D. R. 2013. Public perceptions of wetland restoration benefits in Louisiana. – ICES Journal of Marine Science, 70: 1045–1054. We conducted a referendum-style contingent-valuation survey to investigate public perceptions of wetland restoration benefits including storm protection, ecosystem services, and recreational benefits and to analyse willingness to pay (WTP) for large-scale coastal restoration in Louisiana. Results of the ordered probit and binary probit models indicate that the public perceives both a strong relationship between increased wetland loss and an increased storm risk and a substantial likelihood of increased storm-protection benefits from wetland restoration. However, respondents expressed that they were less likely to believe the improved storm reduction benefits from restoration when they perceived a high frequency of category 3 or greater storms. Additionally, we found that hurricane protection benefits were the most important factor explaining WTP for wetland restoration for preventing expected future land losses in coastal Louisiana.
Overconfidence in model projections
Authors: Brander Keith , Neuheimer Anna , Andersen Ken Haste , Hartvig Martin
Published: August 2013

Brander, K., Neuheimer, A., Andersen, K. H., and Hartvig, M. 2013. Overconfidence in model projections. – ICES Journal of Marine Science, 70: 1065–1068. There is considerable public and political interest in the state of marine ecosystems and fisheries, but the reliability of some recent projections has been called into question. New information about declining fish stocks, loss of biodiversity, climate impacts, and management failure is frequently reported in the major news media, based on publications in prominent scientific journals. Public and political awareness of the generally negative changes taking place in marine ecosystems is welcome, especially if it results in effective remedial action, but the scientific basis for such action must be reliable and uncertainties arising from models and data shortcomings must be presented fully and transparently. Scientific journals play an important role and should require more detailed analysis and presentation of uncertainties.
How to make progress in projecting climate change impacts
Authors: Cheung William W. L. , Pauly Daniel , Sarmiento Jorge L.
Published: August 2013

Cheung, W. W. L., Pauly, D., and Sarmiento, J. L. 2013. How to make progress in projecting climate change impacts. – ICES Journal of Marine Science, 70: 1069–1074. Scientific modelling has become a crucial tool for assessing climate change impacts on marine resources. Brander et al. criticize the treatment of reliability and uncertainty of such models, with specific reference to Cheung et al. (2013, Nature Climate Change, 3: 254–258) and their projections of a decrease in maximum body size of marine fish under climate change. Here, we use the specific criticisms of Brander et al. (2013, ICES Journal of Marine Science) on Cheung et al. (2013) as examples to discuss ways to make progress in scientific modelling in marine science. We address the technical criticisms by Brander et al., then their more general comments on uncertainty. The growth of fish is controlled and limited by oxygen, as documented in a vast body of peer-reviewed literature that elaborates on a robust theory based on abundant data. The results from Cheung et al. were obtained using published, reproducible and peer-reviewed methods, and the results agree with the empirical data; the key assumptions and uncertainties of the analysis were stated. These findings can serve as a step towards improving our understanding of climate change impacts on marine ecosystems. We suggest that, as in other fields of science, it is important to develop incrementally (or radically) new approaches and analyses that extend, and ultimately improve, our understanding and projections of climate change effects on marine ecosystems.
A New Multinomial Accuracy Measure for Polling Bias
Authors: Arzheimer Kai , Evans Jocelyn
Published: August 2013

In this article, we propose a polling accuracy measure for multi-party elections based on a generalization of Martin, Traugott, and Kennedy's two-party predictive accuracy index. Treating polls as random samples of a voting population, we first estimate an intercept only multinomial logit model to provide proportionate odds measures of each party's share of the vote, and thereby both unweighted and weighted averages of these values as a summary index for poll accuracy. We then propose measures for significance testing, and run a series of simulations to assess possible bias from the resulting folded normal distribution across different sample sizes, finding that bias is small even for polls with small samples. We apply our measure to the 2012 French presidential election polls to demonstrate its applicability in tracking overall polling performance across time and polling organizations. Finally, we demonstrate the practical value of our measure by using it as a dependent variable in an explanatory model of polling accuracy, testing the different possible sources of bias in the French data.