bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving dielectric performance in anodic aluminum oxide via detection and passivation of defect states
Authors: Mibus M. , Jensen C. , Hu X. , Knospe C. , Reed M. L. , Zangari G.
Published: June 2014

The electronic and ionic transports in 32–56 nm thick anodic aluminum oxide films are investigated before and after a 1-h anneal at 200–400 °C in argon. Results are correlated to their defect density as measured by the Mott-Schottky technique. Solid state measurements show that electronic conduction upon annealing is hindered by an increase in the Schottky emission barrier, induced by a reduction in dopant density. Using an electrochemical contact, the films fail rapidly under cathodic polarization, unless defect density is decreased down to 1017 cm−3, resulting in a three order of magnitude reduction in current and no visible gas evolution. Under anodic polarization, the decrease in defect density delays the onset of ionic conduction as well as further oxide growth and failure.
Love stories can be unpredictable: Jules et Jim in the vortex of life
Authors: Dercole Fabio , Rinaldi Sergio
Published: June 2014

Love stories are dynamic processes that begin, develop, and often stay for a relatively long time in a stationary or fluctuating regime, before possibly fading. Although they are, undoubtedly, the most important dynamic process in our life, they have only recently been cast in the formal frame of dynamical systems theory. In particular, why it is so difficult to predict the evolution of sentimental relationships continues to be largely unexplained. A common reason for this is that love stories reflect the turbulence of the surrounding social environment. But we can also imagine that the interplay of the characters involved contributes to make the story unpredictable—that is, chaotic. In other words, we conjecture that sentimental chaos can have a relevant endogenous origin. To support this intriguing conjecture, we mimic a real and well-documented love story with a mathematical model in which the environment is kept constant, and show that the model is chaotic. The case we analyze is the triangle described in Jules et Jim, an autobiographic novel by Henri-Pierre Roché that became famous worldwide after the success of the homonymous film directed by François Truffaut.
Hydration dynamics of aqueous glucose probed with polarization-resolved fs-IR spectroscopy
Authors: Groot C. C. M. , Bakker H. J.
Published: June 2014

The dynamics of water in aqueous solutions of glucose have been investigated using polarization-resolved femtosecond infrared spectroscopy of the hydroxyl stretch vibrations of water and glucose. Using reference measurements on solutions of glucose in dimethylsulfoxide and a spectral decomposition model, we are able to distinguish the reorientation dynamics of the glucose and water hydroxyl groups. We find that the water reorientation dynamics strongly slow down in the presence of glucose.
Optimization of spin-torque switching using AC and DC pulses
Authors: Dunn Tom , Kamenev Alex
Published: June 2014

We explore spin-torque induced magnetic reversal in magnetic tunnel junctions using combined AC and DC spin-current pulses. We calculate the optimal pulse times and current strengths for both AC and DC pulses as well as the optimal AC signal frequency, needed to minimize the Joule heat lost during the switching process. The results of this optimization are compared against numeric simulations. Finally, we show how this optimization leads to different dynamic regimes, where switching is optimized by either a purely AC or DC spin-current, or a combination AC/DC spin-current, depending on the anisotropy energies and the spin-current polarization.
Nanomechanical switches based on metal-insulator-metal capacitors from a standard complementary-metal-oxide semiconductor technology
Authors: Muñoz-Gamarra J. L. , Uranga A. , Barniol N.
Published: June 2014

We report experimental demonstrations of contact-mode nano-electromechanical switches obtained using a capacitor module based on metal-insulator-metal configuration of a standard commercial complementary metal oxide semiconductor technology. The developed 2 terminals Titanium Nitride switches operate at low voltages (∼10 V) thanks to its small gap (27 nm), showing an excellent ION/IOFF ratio (104) and abrupt behavior (5 mV/decade, one decade of current change is achieved with a 5 mV voltage variation). A switch configuration is also presented where using two electrodes three different contact mode states can be obtained, adding functionalities to mechanical switches configurations.
Note: Optimized circuit for excitation and detection with one pair of electrodes for improved Fourier transform ion cyclotron resonance mass spectrometry
Authors: Chen T. , Beu S. C. , Kaiser N. K. , Hendrickson C. L.
Published: June 2014

A conventional Fourier transform-Ion Cyclotron Resonance (ICR) detection cell is azimuthally divided into four equal sections. One pair of opposed electrodes is used for ion cyclotron excitation, and the other pair for ion image charge detection. In this work, we demonstrate that an appropriate electrical circuit facilitates excitation and detection on one pair of opposed electrodes. The new scheme can be used to minimize the number of electrically independent ICR cell electrodes and/or improve the electrode geometry for simultaneously increased ICR signal magnitude and optimal post-excitation radius, which results in higher signal-to-noise ratio and decreased space-charge effects.
Role of deuterium desorption kinetics on the thermionic emission properties of polycrystalline diamond films with respect to kinetic isotope effects
Authors: Paxton W. F. , Brooks M. M. , Howell M. , Tolk N. , Kang W. P. , Davidson J. L.
Published: June 2014

The desorption kinetics of deuterium from polycrystalline chemical vapor deposited diamond films were characterized by monitoring the isothermal thermionic emission current behavior. The reaction was observed to follow a first-order trend as evidenced by the decay rate of the thermionic emission current over time which is in agreement with previously reported studies. However, an Arrhenius plot of the reaction rates at each tested temperature did not exhibit the typical linear behavior which appears to contradict past observations of the hydrogen (or deuterium) desorption reaction from diamond. This observed deviation from linearity, specifically at lower temperatures, has been attributed to non-classical processes. Though no known previous studies reported similar deviations, a reanalysis of the data obtained in the present study was performed to account for tunneling which appeared to add merit to this hypothesis. Additional investigations were performed by reevaluating previously reported data involving the desorption of hydrogen (as opposed to deuterium) from diamond which further indicated this reaction to be dominated by tunneling at the temperatures tested in this study (<775 °C). An activation energy of 3.19 eV and a pre-exponential constant of 2.3 × 1012 s−1 were determined for the desorption reaction of deuterium from diamond which is in agreement with previously reported studies.
Dynamics of multiple viscoelastic carbon nanotube based nanocomposites with axial magnetic field
Authors: Karličić Danilo , Murmu Tony , Cajić Milan , Kozić Predrag , Adhikari Sondipon
Published: June 2014

Nanocomposites and magnetic field effects on nanostructures have received great attention in recent years. A large amount of research work was focused on developing the proper theoretical framework for describing many physical effects appearing in structures on nanoscale level. Great step in this direction was successful application of nonlocal continuum field theory of Eringen. In the present paper, the free transverse vibration analysis is carried out for the system composed of multiple single walled carbon nanotubes (MSWCNT) embedded in a polymer matrix and under the influence of an axial magnetic field. Equivalent nonlocal model of MSWCNT is adopted as viscoelastically coupled multi-nanobeam system (MNBS) under the influence of longitudinal magnetic field. Governing equations of motion are derived using the Newton second low and nonlocal Rayleigh beam theory, which take into account small-scale effects, the effect of nanobeam angular acceleration, internal damping and Maxwell relation. Explicit expressions for complex natural frequency are derived based on the method of separation of variables and trigonometric method for the “Clamped-Chain” system. In addition, an analytical method is proposed in order to obtain asymptotic damped natural frequency and the critical damping ratio, which are independent of boundary conditions and a number of nanobeams in MNBS. The validity of obtained results is confirmed by comparing the results obtained for complex frequencies via trigonometric method with the results obtained by using numerical methods. The influence of the longitudinal magnetic field on the free vibration response of viscoelastically coupled MNBS is discussed in detail. In addition, numerical results are presented to point out the effects of the nonlocal parameter, internal damping, and parameters of viscoelastic medium on complex natural frequencies of the system. The results demonstrate the efficiency of the suggested methodology to find the closed form solutions for the free vibration response of multiple nanostructure systems under the influence of magnetic field.
Flexibility of phospholipids with saturated and unsaturated chains studied by Raman scattering: The effect of cholesterol on dynamical and phase transitions
Authors: Surovtsev N. V. , Dzuba S. A.
Published: June 2014

Raman scattering spectra were obtained at 25–320 K for bilayers prepared from saturated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and mono-unsaturated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) phospholipids, with and without cholesterol. Raman intensities were measured at modes sensitive to lipid inter-chain interactions and/or intra-chain torsional motion (asymmetric CH2 stretching at 2880 cm−1) and to the conformational state of lipids (C–C stretching at 1130 cm−1). These intensities decreased with temperature, which could be ascribed to increased lipid flexibility. For cholesterol-free and cholesterol-containing DPPC bilayers, the decrease of Raman intensities observed above ∼200 K could be related to the phenomenon of dynamical transition known for biological systems near these temperatures. For a cholesterol-free POPC bilayer, the decrease of intensity for the asymmetric CH2 stretching mode started at a lower temperature, above 100 K, while the addition of cholesterol shifted this starting temperature to a more normal ∼200 K value. The low-temperature lipid flexibility in the case of POPC was related to the abundance of free-volume holes, which disappeared in presence of cholesterol. Near gel-fluid phase transitions, Raman intensities for cholesterol-free bilayers dropped sharply, while for cholesterol-containing bilayers, they changed smoothly.
Maximal entropy random walk improves efficiency of trapping in dendrimers
Authors: Peng Xin , Zhang Zhongzhi
Published: June 2014

We use maximal entropy random walk (MERW) to study the trapping problem in dendrimers modeled by Cayley trees with a deep trap fixed at the central node. We derive an explicit expression for the mean first passage time from any node to the trap, as well as an exact formula for the average trapping time (ATT), which is the average of the source-to-trap mean first passage time over all non-trap starting nodes. Based on the obtained closed-form solution for ATT, we further deduce an upper bound for the leading behavior of ATT, which is the fourth power of ln N, where N is the system size. This upper bound is much smaller than the ATT of trapping depicted by unbiased random walk in Cayley trees, the leading scaling of which is a linear function of N. These results show that MERW can substantially enhance the efficiency of trapping performed in dendrimers.
Towards understanding junction degradation in cadmium telluride solar cells
Authors: Nardone Marco
Published: June 2014

A degradation mechanism in cadmium telluride (CdTe/CdS) solar cells is investigated using time-dependent numerical modeling to simulate various temperature, bias, and illumination stress conditions. The physical mechanism is based on defect generation rates that are proportional to nonequilibrium charge carrier concentrations. It is found that a commonly observed degradation mode for CdTe/CdS solar cells can be reproduced only if defects are allowed to form in a narrow region of the absorber layer close to the CdTe/CdS junction. A key aspect of this junction degradation is that both mid-gap donor and shallow acceptor-type defects must be generated simultaneously in response to photo-excitation or applied bias. The numerical approach employed here can be extended to study other mechanisms for any photovoltaic technology.
Bipolar resistance switching in Pt/CuOx/Pt via local electrochemical reduction
Authors: D'Aquila Kenneth , Phatak Charudatta , Holt Martin V. , Stripe Benjamin D. , Tong Sheng , Park Woon Ik , Hong Seungbum , Petford-Long Amanda K.
Published: June 2014

The local changes in copper oxidation state and the corresponding resistance changes in Pt/CuOx/Pt nanoscale heterostructures have been investigated using x-ray nanoprobe spectro-microscopy and current-voltage characterization. After gentle electroforming, during which the current-voltage behavior remains non-linear, the low resistance state was reached, and we observed regions of 160 nm width that show an increase in Cu K-alpha fluorescence intensity, indicative of partial reduction of the CuOx. Analysis of the current voltage curves showed that the dominant conduction mechanism is Schottky emission and that the resistance state is correlated with the Schottky barrier height. We propose that the reversible resistivity change in these Pt/CuOx/Pt heterostructures occurs through local electrochemical reduction leading to change of the Schottky barrier height at the interface between Pt and the reduced CuOx layers and to change of the CuOx resistivity within laterally confined portions of the CuOx layer. These experiments reveal important insights into the mechanism of resistance switching of Pt/CuOx/Pt performed in a current and voltage regime that does not create a metallic conduction path.
Transient temperature response of near field scanning optical microscope probes under pulsed illumination
Authors: Sundaram Vijay M. , Soni Alok , Wen Sy-Bor
Published: June 2014

Time resolved thermoreflectance imaging with a nanosecond laser is applied to study the transient thermal response of near field scanning optical microscope (NSOM) probes driven by either microsecond (μs) or nanosecond (ns) laser pulses. It is found that when the laser energies are the same, μs and ns laser pulses show similar trend of close to adiabatic heating during the laser pulse and close to conductive cooling after the laser pulse. The peak temperature is almost linear with respect to input laser energy for the energy selected. The peak temperature of the NSOM probe is increased when the aperture size of the probe is smaller and when the incident laser wavelength is shorter. However, compared with μs laser pulses, small physical damages appear around the NSOM aperture, which gradually decreases the optical-thermal energy conversion efficiency in the NSOM probe when ns laser pulses are applied.
X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility
Authors: Hakel P. , Kyrala G. A. , Bradley P. A. , Krasheninnikova N. S. , Murphy T. J. , Schmitt M. J. , Tregillis I. L. , Kanzleieter R. J. , Batha S. H. , Fontes C. J. , Sherrill M. E. , Kilcrease D. P. , Regan S. P.
Published: June 2014

A series of experiments featuring laser-imploded plastic-shell targets filled with hydrogen or deuterium were performed on the National Ignition Facility. The shells (some deuterated) were doped in selected locations with Cu, Ga, and Ge, whose spectroscopic signals (indicative of local plasma conditions) were collected with a time-integrated, 1-D imaging, spectrally resolved, and absolute-intensity calibrated instrument. The experimental spectra compare well with radiation hydrodynamics simulations post-processed with a non-local thermal equilibrium atomic kinetics and spectroscopic-quality radiation-transport model. The obtained degree of agreement between the modeling and experimental data supports the application of spectroscopic techniques for the determination of plasma conditions, which can ultimately lead to the validation of theoretical models for thermonuclear burn in the presence of mix. Furthermore, the use of a lower-Z dopant element (e.g., Fe) is suggested for future experiments, since the ∼2 keV electron temperatures reached in mixed regions are not high enough to drive sufficient H-like Ge and Cu line emissions needed for spectroscopic plasma diagnostics.
Perturbation analysis of electromagnetic geodesic acoustic modes
Authors: Ren Haijun
Published: June 2014

Lagrangian displacement and magnetic field perturbation response to the geodesic acoustic mode is analyzed by using the ideal magnetohydrodynamic equations in a large-aspect-ratio tokamak. δBθ, the poloidal component of magnetic field perturbation, has poloidal wave number m = 2 created by the poloidal displacement ξθ. The parallel perturbation of magnetic field, δB∥, has a poloidally asymmetric structure with m = 1 and is on the same order of magnitude with δBθ to the leading order. The radial displacement ξr is of order O(βϵξθ) but plays a significant role in determining δB∥, where β is the plasma/magnetic pressure ratio and ϵ is the inverse aspect ratio.
Resistive switching characteristics of polycrystalline SrTiO3 films
Authors: Jong Choi Hyung , Won Park Suk , Deok Han Gwon , Na Junhong , Kim Gyu-Tae , Hyung Shim Joon
Published: June 2014

Strontium titanate (STO) thin films 90 nm in thickness were grown on a Pt substrate through atomic layer deposition (ALD). The as-deposited ALD STO grown with an ALD cycle ratio of 1:1 (Sr:Ti) was in an amorphous phase, and annealing at 800 °C in air crystallized the films into the perovskite phase. This phase change was confirmed by x-ray diffraction and transmission electron microscopy. The as-deposited ALD STO exhibited no discernible switching mechanism, whereas unipolar switching behavior was reproducibly observed with a high resistance ratio (108–109) and strict separation of the set/reset voltages and currents in the annealed ALD STO. Mechanisms for charge transport in both the low- and high-resistance states and for resistive switching in the annealed ALD STO are also proposed.
Microstructure and conductance-slope of InAs/GaSb tunnel diodes
Authors: Iutzi Ryan M. , Fitzgerald Eugene A.
Published: June 2014

InAs/GaSb and similar materials systems have generated great interest as a heterojunction for tunnel field effect transistors (TFETs) due to favorable band alignment. However, little is currently understood about how such TFETs are affected by materials defects and nonidealities. We present measurements of the conductance slope for various InAs/GaSb heterojunctions via two-terminal electrical measurements, which removes three-terminal parasitics and enables direct study on the effect of microstructure on tunnelling. Using this, we can predict how subthreshold swings in TFETs can depend on microstructure. We also demonstrate growth and electrical characterization for structures grown by metalorganic chemical vapor deposition (MOCVD)—a generally more scalable process compared with molecular beam epitaxy (MBE). We determine that misfit dislocations and point defects near the interface can lead to energy states in the band-gap and local band bending that result in trap-assisted leakage routes and nonuniform band alignment across the junction area that lower the steepness of the conductance slope. Despite the small lattice mismatch, misfit dislocations still form in InAs on GaSb due to relaxation as a result of large strain from intermixed compositions. This can be circumvented by growing GaSb on InAs, straining the GaSb underlayer, or lowering the InAs growth temperature in the region of the interface. The conductance slope can also be improved by annealing the samples at higher temperatures, which we believe acts to annihilate point defects and average out major fluctuations in band alignment across the interface. Using a combination of these techniques, we can greatly improve the steepness of the conductance slope which could result in steeper subthreshold swings in TFETs in the future.
Formation and ultraslow propagation of infrared solitons in graphene under an external magnetic field
Authors: Ding Chunling , Yu Rong , Li Jiahua , Hao Xiangying , Wu Ying
Published: June 2014

Unusual dispersion relation of graphene nanoribbons for electrons can lead to an exceptionally strong optical response in the infrared regime and exhibits a very good tunable frequency. According to quantum optics and solid-material scientific principles, here we show the possibility to generate ultraslow infrared bright and dark solitons in graphene under the action of strong magnetic and infrared laser fields. By means of quantum-mechanical density-matrix formalism, we derive the equations of motion that govern the nonlinear evolution of the probe-pulse envelope in this scheme. It is found that, by properly choosing the parameters of the system, the formation and ultraslow propagation of infrared spatial solitons originate from the balance between nonlinear effects and the dispersion properties of the graphene under infrared excitation. Moreover, the unique electronic properties and selection rules near the Dirac point provide more freedom for us to study the linear and nonlinear dynamical responses of the photonics and graphene system. These results may have potential applications in telecommunication and optical information processing.
Dramatic enhancement of fullerene anion formation in polymer solar cells by thermal annealing: Direct observation by electron spin resonance
Authors: Liu Dong , Nagamori Tatsuya , Yabusaki Masaki , Yasuda Takeshi , Han Liyuan , Marumoto Kazuhiro
Published: June 2014

Using electron spin resonance (ESR), we clarified the origin of the efficiency degradation of polymer solar cells containing a lithium-fluoride (LiF) buffer layer created by a thermal annealing process after the deposition of an Al electrode (post-annealing). The device structure was indium-tin-oxide/ poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)/poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM)/LiF/Al. Three samples consisting of quartz/P3HT:PCBM/LiF/Al, quartz/P3HT:PCBM/Al, and quartz/PCBM/LiF/Al were investigated and compared. A clear ESR signal from radical anions on the PCBM was observed after LiF/Al was deposited onto a P3HT:PCBM layer because of charge transfer at the interface between the PCBM and the LiF/Al, which indicated the formation of PCBM−Li+ complexes. The number of radical anions on the PCBM was enhanced remarkably by the post-annealing process; this enhancement was caused by the surface segregation of PCBM and by the dissociation of LiF at the Al interface by the post-annealing process. The formation of a greater number of anions enhanced the electron scattering, decreased the electron-transport properties of the PCBM molecules, and caused an energy-level shift at the interface. These effects led to degradation in the device performance.
Uniform nano-ripples on the sidewall of silicon carbide micro-hole fabricated by femtosecond laser irradiation and acid etching
Authors: Khuat Vanthanh , Chen Tao , Gao Bo , Si Jinhai , Ma Yuncan , Hou Xun
Published: June 2014

Uniform nano-ripples were observed on the sidewall of micro-holes in silicon carbide fabricated by 800-nm femtosecond laser and chemical selective etching. The morphology of the ripple was analyzed using scanning electronic microscopy. The formation mechanism of the micro-holes was attributed to the chemical reaction of the laser affected zone with mixed solution of hydrofluoric acid and nitric acid. The formation of nano-ripples on the sidewall of the holes could be attributed to the standing wave generated in z direction due to the interference between the incident wave and the reflected wave.
Temperature dependent electrical transport studies of self-aligned ZnO nanorods/Si heterostructures deposited by sputtering
Authors: Ranwa Sapana , Kumar Kulriya Pawan , Dixit Vivek , Kumar Mahesh
Published: June 2014

Self-aligned ZnO nanorods (NRs) were grown on n-Si(100) substrate by RF sputtering techniques. The NRs are uniformly grown on 2-inch wafer along [0001] direction. Single-crystalline wurtzite structure of ZnO NRs was confirmed by X-ray diffraction. The average diameter, height, and density of NRs are found 48 nm, 750 nm, and 1.26 × 1010 cm−2, respectively. The current-voltages (I-V) characteristics of ZnO NRs/Si heterojunction (HJ) were studied in the temperature range of 120–300 K and it shows a rectifying behavior. Barrier height (ϕB) and ideality factor (η) were estimated from thermionic emission model and found to be highly temperature dependent in nature. Richardson constant (A*) was evaluated using Richardson plot of ln(Io/T2) versus q/kT plot by linear fitting in two temperature range 120–180 K and 210–300 K. Large deviation in Richardson constant from its theoretical value of n-Si indicates the presence of barrier inhomogeneities at HJ. Double Gaussian distribution of barrier height with thermionic equation gives mean barrier heights of 0.55 ± 0.01 eV and 0.86 ± 0.02 eV for two different temperature regions 120–180 K and 210–300 K, respectively. Modified Richardson plot provided two values of Richardson constant for two temperature regions. However, for higher temperature range (210–300 K), the calculated value of Richardson constant ∼123 A cm−2 K−2 was close to the ideal Richardson constant for n-Si.
Piezoelectricity and electrostriction in biocompatible (Na,K)NbO3 nanofiber scaffolds
Authors: Jalalian A. , Grishin A. M.
Published: June 2014

Single phase and highly crystalline biocompatible ferroelectric (Na,K)NbO3 (NKN) nanofibers were synthesized by sol-gel assisted electrospinning technique. Low amplitude piezoelectric response as well as electrostriction effect in NKN fibers were examined using piezoelectric force microscopy technique. Piezoelectric coefficient d33 is strongly anisotropic varying from 75.8 to 18.3 pm/V for, respectively, out-of-axis and on-axis oriented ferroelectric domains in NKN fibers. Hysteresis P-E loop for individual nanofiber reconstructed from the bipolar E-field-induced butterfly strain curve yields: coercive field Ec = 31 kV/cm, remnant Pr = 6.2 μC/cm2, and the maximum achieved polarization Pmax = 21.2 μC/cm2. Enhanced piezoelectric effect and strong electrostriction promise NKN fibers as electrically polarizable scaffolds for tissue engineering and for energy harvesting biocompatible nanogenerators.
Activated carbon/manganese dioxide hybrid electrodes for high performance thin film supercapacitors
Authors: Jang Yunseok , Jo Jeongdai , Jang Hyunjung , Kim Inyoung , Kang Dongwoo , Kim Kwang-Young
Published: June 2014

We combine the activated carbon (AC) and the manganese dioxide (MnO2) in a AC/MnO2 hybrid electrode to overcome the low capacitance of activated carbon and MnO2 by exploiting the large surface area of AC and the fast reversible redox reaction of MnO2. An aqueous permanganate (MnO4−) is converted to MnO2 on the surface of the AC electrode by dipping the AC electrode into an aqueous permanganate solution. The AC/MnO2 hybrid electrode is found to display superior specific capacitance of 290 F/g. This shows that supercapacitors classified as electric double layer capacitors and pseudocapacitors can be combined together.
Nitrobenzene anti-parallel dimer formation in non-polar solvents
Authors: Shikata Toshiyuki , Sakai Yuji , Watanabe Junji
Published: June 2014

We investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz), which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3 THz for the dielectric measurements and 8 THz for the scattering experiments at 20 °C. The dielectric relaxation strength of the system was substantially smaller than the proportionality to the concentration in a concentrated regime and showed a Kirkwood correlation factor markedly lower than unity; gK ∼ 0.65. This observation revealed that NO2-Bz has a tendency to form dimers, (NO2-Bz)2, in anti-parallel configurations for the dipole moment with increasing concentration of the two solvents. Both the dielectric and scattering data exhibited fast and slow Debye-type relaxation modes with the characteristic time constants ∼7 and ∼50 ps in a concentrated regime (∼15 and ∼30 ps in a dilute regime), respectively. The fast mode was simply attributed to the rotational motion of the (monomeric) NO2-Bz. However, the magnitude of the slow mode was proportional to the square of the concentration in the dilute regime; thus, the mode was assigned to the anti-parallel dimer, (NO2-Bz)2, dissociation process, and the slow relaxation time was attributed to the anti-parallel dimer lifetime. The concentration dependencies of both the dielectric and scattering data show that the NO2-Bz molecular processes are controlled through a chemical equilibrium between monomers and anti-parallel dimers, 2NO2-Bz ↔ (NO2-Bz)2, due to a strong dipole-dipole interaction between nitro groups.
Silver substrates for surface enhanced Raman scattering: Correlation between nanostructure and Raman scattering enhancement
Authors: Santoro G. , Yu S. , Schwartzkopf M. , Zhang P. , Koyiloth Vayalil Sarathlal , Risch J. F. H. , Rübhausen M. A. , Hernández M. , Domingo C. , Roth S. V.
Published: June 2014

The fabrication of substrates for Surface Enhanced Raman Scattering (SERS) applications matching the needs for high sensitive and reproducible sensors remains a major scientific and technological issue. We correlate the morphological parameters of silver (Ag) nanostructured thin films prepared by sputter deposition on flat silicon (Si) substrates with their SERS activity. A maximum enhancement of the SERS signal has been found at the Ag percolation threshold, leading to the detection of thiophenol, a non-resonant Raman probe, at concentrations as low as 10−10M, which corresponds to enhancement factors higher than 7 orders of magnitude. To gain full control over the developed nanostructure, we employed the combination of in-situ time-resolved microfocus Grazing Incidence Small Angle X-ray Scattering with sputter deposition. This enables to achieve a deepened understanding of the different growth regimes of Ag. Thereby an improved tailoring of the thin film nanostructure for SERS applications can be realized.
Activating Territorial Stigma: Gentrifying Marginality on Edinburgh's Periphery
Authors: Kallin Hamish , Slater Tom
Published: June 2014

This paper reaffirms the importance of politics in theories on gentrification through analysis of a recent ‘regeneration’ project based in Craigmillar, a stigmatised district on the southeastern edge of Edinburgh. It sketches the historical backdrop to the area's stigma as a place ‘outside’ the city, using qualitative research on the Craigmillar Festival Society to highlight how this stigma was produced and intensified as well as contested. By stressing that the main intention of the ‘regeneration’ project was to attract more affluent residents to Craigmillar, we show how territorial stigmatisation and ‘regeneration’ through gentrification form two sides of the same conceptual and policy coin: the “blemish of place” becomes a target and rationale for ‘fixing’ the area, thus obviating and obstructing policies aimed at attacking deprivation, inequality, or the structural problems of advanced marginality. The state's role in creating the very stigma it then insists on scrubbing highlights a major contradiction in contemporary urban policy.
Is Your Commute Killing You? On the Mortality Risks of Long-Distance Commuting
Authors: Sandow Erika , Westerlund Olle , Lindgren Urban
Published: June 2014

There is a general belief that expanding labour-market regions, triggered by increased commuting, have positive economic effects on individuals, firms, and society. Recently, however, scholars have reported possible negative outcomes related to health and well-being. Based on these findings, this study addresses the association between long-distance commuting, and mortality. Using longitudinal individual data from between 1985 and 2008, focusing on 55-year-olds in 1994, we model mortality through propensity score matching and Kaplan–Meyer estimates of survival among long-distance commuters and matched controls from the population travelling short distances to work. The results indicate that women who have experienced long-distance commuting face a significantly higher mortality risk compared with women with short commutes to work. This seems to be driven by variations in income and education: for example, for women with long-distance commuting experience, substantially lower survival rates are found among those with low education and low income. A very different picture emerges for men, for whom mortality risks do not seem to be associated with long-distance commuting. Our findings suggest that men and women are subject to different mechanisms regarding the nexus between commuting and mortality.
“It's Not a Bairro, is It?”: Subsistence Sociability and Focused Avoidance in a Public Housing Estate
Authors: Pereira Virgílio Borges , Queirós João
Published: June 2014

This paper draws on a multidisciplinary study of state policy, housing provision, and the social question in Porto, Portugal, over the past half century, combining ethnography, in-depth interviews, and a survey of local families. It examines the trajectory of one of the city's largest and most notorious public housing estates to map out how transformations in its social composition and in the mix of state action have affected how residents deal with the disparaging public image attached to their place of residence. Against analytical simplification, we spotlight responses to territorial stigmatization that muddle the ‘exit–voice’ or ‘conformity–rejection’ dichotomies and reveal the social parameters that determine the symbolic boundaries, sociability patterns, and daily face-to-face interactions found in this housing estate. Strategies of ‘subsistence sociability’ and ‘focused avoidance’ have enabled local families to cope with the spatial taint hovering over their bairro while avoiding both the high costs of exit and the uncertain investment in collective action.
Postsynaptic activity reverses the sign of the acetylcholine-induced long-term plasticity of GABA
A
inhibition
Authors: Domínguez Soledad , Fernández de Sevilla David , Buño Washington
Published: June 2014

Significance

Cholinergic activity regulates excitability and plasticity in neuronal circuits through the activation of muscarinic and nicotinic receptors. Here we demonstrate that muscarinic receptors can depress or enhance synaptic inhibition in the hippocampal CA1 region, depending on the quiescent or active state of the postsynaptic target CA1 pyramidal neuron, the main hippocampal CA1 output. These effects regulate inhibition from a presynaptic to a postsynaptic site, a relocation that could be essential to control activity associated with cognitive functions and the homeostatic regulation of abnormal hyperexcitability.
Hypoxia-inducible factors and RAB22A mediate formation of microvesicles that stimulate breast cancer invasion and metastasis
Authors: Wang Ting , Gilkes Daniele M. , Takano Naoharu , Xiang Lisha , Luo Weibo , Bishop Corey J. , Chaturvedi Pallavi , Green Jordan J. , Semenza Gregg L.
Published: June 2014

Significance

Cancer cells release from their cell surface membrane-lined microvesicles (MVs), which contain proteins, mRNAs, and microRNAs that can be taken up by other cells. We report that breast cancer cells exposed to decreased oxygen availability (hypoxia) increase their production of MVs, which stimulate invasion and metastasis by recipient breast cancer cells. Increased MV shedding by hypoxic cells requires expression of hypoxia-inducible factors (HIFs), which activate transcription of the
RAB22A
gene, and expression of the small GTPase RAB22A, which is a protein that localizes to budding MVs. Our results delineate a molecular mechanism by which hypoxia increases invasion and metastasis by stimulating MV shedding and provide further evidence that addition of HIF inhibitors to current treatment regimens may improve clinical outcome.
The Unfolding of Unreason: Javad Tabatabai's Idea of Political Decline in Iran
Authors: Boroujerdi Mehrzad , Shomali Alireza
Published: June 2014

Javad Tabatabai, a leading theorist and historian of political thought in Iran, has presented a controversial theory regarding the causes of the decline of political thought and society in Iran over the last few centuries. His ideas on Iranian decline have affected the intellectual debates on modernity and democracy currently underway in Iran. Tabatabai's career-long research has revolved around this question: “What conditions made modernity possible in Europe and led to its abnegation in Iran?” He answers this question by adopting a “Hegelian approach” that privileges a philosophical reading of history on the assumption that philosophical thought is the foundation and essence of any political community and the basis for any critical analysis of it as well. This article critically engages with Tabatabai's ideas of “crisis,” and “decline” by challenging his exposition of the Persian tradition.
Bactericidal activity of nukacin ISK-1: an alternative mode of action
Authors: Roy Urmi , Islam Mohammad Riazul , Nagao Jun-ichi , Iida Hiroshi , Mahin Abdullah-Al , Li Mengqi , Zendo Takeshi , Nakayama Jiro , Sonomoto Kenji
Published: June 2014

We previously reported bacteriostatic action of nukacin ISK-1 against Bacillus subtilis JCM 1465T. Here, we found its bactericidal activity against Micrococcus luteus DSM 1790 and Staphylococcus simulans 22, showing decrease in cell viability, cell lysis, and dissipation of the membrane potential. Moreover, leakage of small molecules such as K+, suggested the formation of small-sized or specific K+-conducting-pores by nukacin ISK-1.
A genome-wide survey of homeodomain-leucine zipper genes and analysis of cold-responsive HD-Zip I members’ expression in tomato
Authors: Zhang Zhenzhu , Chen Xiuling , Guan Xin , Liu Yang , Chen Hongyu , Wang Tingting , Mouekouba Liana Dalcantara Ongouya , Li Jingfu , Wang Aoxue
Published: June 2014

Homeodomain-leucine zipper (HD-Zip) proteins are a kind of transcriptional factors that play a vital role in plant growth and development. However, no detailed information of HD-Zip family in tomato has been reported till now. In this study, 51 HD-Zip genes (SlHZ01-51) in this family were identified and categorized into 4 classes by exon–intron and protein structure in tomato (Solanum lycopersicum) genome. The synthetical phylogenetic tree of tomato, Arabidopsis and rice HD-Zip genes were established for an insight into their evolutionary relationships and putative functions. The results showed that the contribution of segmental duplication was larger than that of tandem duplication for expansion and evolution of genes in this family of tomato. The expression profile results under abiotic stress suggested that all SlHZ I genes were responsive to cold stress. This study will provide a clue for the further investigation of functional identification and the role of tomato HD-Zip I subfamily in plant cold stress responses and developmental events.
Heat kernel based decomposition of spaces of distributions in the framework of Dirichlet spaces
Authors: Kerkyacharian Gerard , Petrushev Pencho
Published: June 2014

Classical and nonclassical Besov and Triebel-Lizorkin spaces with complete range of indices are developed in the general setting of Dirichlet space with a doubling measure and local scale-invariant Poincaré inequality. This leads to a heat kernel with small time Gaussian bounds and Hölder continuity, which play a central role in this article. Frames with band limited elements of sub-exponential space localization are developed, and frame and heat kernel characterizations of Besov and Triebel-Lizorkin spaces are established. This theory, in particular, allows the development of Besov and Triebel-Lizorkin spaces and their frame and heat kernel characterization in the context of Lie groups, Riemannian manifolds, and other settings.
Cubular tubular groups
Authors: Wise Daniel
Published: June 2014

Let

G
G

split as a finite graph of free abelian groups with cyclic edge groups. We characterize when

G
G

acts freely on a CAT(0) cube complex. We show that if

G
G

acts properly and semi-simply on a CAT(0) space, then

G
G

acts freely on a CAT(0) cube complex.
Generalized blow-up of corners and fiber products
Authors: Kottke Chris , Melrose Richard
Published: June 2014

Real blow-up, including inhomogeneous versions, of boundary faces of a manifold (with corners) is an important tool for resolving singularities, degeneracies and competing notions of homogeneity. These constructions are shown to be particular cases of generalized boundary blow-up in which a new manifold and blow-down map are constructed from, and conversely determine, combinatorial data at the boundary faces in the form of a refinement of the basic monoidal complex of the manifold. This data specifies which notion of homogeneity is realized at each of the boundary hypersurfaces in the blown-up space.

As an application of this theory, the existence of fiber products is examined for the natural smooth maps in this context, the b-maps. Transversality of the b-differentials is shown to ensure that the set-theoretic fiber product of two maps is a binomial variety. Properties of these (extrinsically defined) spaces, which generalize manifolds but have mild singularities at the boundary, are investigated, and a condition on the basic monoidal complex is found under which the variety has a smooth structure. Applied to b-maps this additional condition with transversality leads to a universal fiber product in the context of manifolds with corners. Under the transversality condition alone the fiber product is resolvable to a smooth manifold by generalized blow-up and then has a weaker form of the universal mapping property requiring blow-up of the domain.
Smooth function extension based on high dimensional unstructured data
Authors: Chui Charles , Mhaskar H.
Published: June 2014

Many applications, including the image search engine, image inpainting, hyperspectral image dimensionality reduction, pattern recognition, and time series prediction, can be facilitated by considering the given discrete data–set as a point-cloudP{\mathcal P}in some high dimensional Euclidean spaceRs{\mathbb R}^{s}. Then the problem is to extend a desirable objective functionfffrom a certain relatively smaller training subsetC⊂P\mathcal {C}\subset {\mathcal P}to some continuous manifoldX⊂Rs{\mathbb X}\subset {\mathbb R}^{s}that containsP{\mathcal P}, at least approximately. More precisely, when the point cloudP{\mathcal P}of the given data–set is modeled in the abstract by some unknown compact manifold embedded in the ambient Euclidean spaceRs{\mathbb R}^{s}, the extension problem can be considered as the interpolation problem of seeking the objective function on the manifoldX{\mathbb X}that agrees withffonC\mathcal {C}under certain desirable specifications. For instance, by considering groups of cardinalityssof data values as points in a point-cloud inRs{\mathbb R}^{s}, such groups that are far apart in the original spatial data domain inR1{\mathbb R}^{1}orR2{\mathbb R}^{2}, but have similar geometric properties, can be arranged to be close neighbors on the manifold. The objective of this paper is to incorporate the consideration of data geometry and spatial approximation, with immediate implications to the various directions of application areas. Our main result is a point-cloud interpolation formula that provides a near-optimal degree of approximation to the target objective function on the unknown manifold.
The Impact of Information Provision on Agglomeration Bonus Performance: An Experimental Study on Local Networks
Authors: Banerjee Simanti , de Vries Frans P. , Hanley Nick , van Soest Daan P.
Published: June 2014

The agglomeration bonus is an incentive mechanism to induce adjacent landowners to spatially coordinate their land use for the delivery of ecosystem services from farmland. This paper uses laboratory experiments to explore the performance of the agglomeration bonus in achieving the socially optimal land management configuration in a local network environment where the information available to subjects varies and the strategic setting is unfavorable for efficient coordination. The experiments indicate that if subjects are informed about both their direct and indirect neighbors' actions, they are more likely to produce the socially optimal configuration. Thus effectiveness of the policy can be improved by implementing information dissemination exercises among landowners. However given the adverse strategic setting, increased game experience leads to coordination failure and optimal land choices only at the localized level independent of the information available to subjects. Thus success of the agglomeration bonus scheme on real landscapes will have to take account of the roles of both information and experience on participant behavior.
Future-proofing marine protected area networks for cold water coral reefs
Authors: Jackson E. L. , Davies A. J. , Howell K. L. , Kershaw P. J. , Hall-Spencer J. M.
Published: June 2014

Ideally, networks of marine protected areas should be designed with consideration for future changes. We examine how this could be tackled using the example of cold-water coral reefs which provide a number of ecosystem services but are vulnerable to both managed pressures (e.g. deep-water trawling) and unmanaged pressures (e.g. ocean acidification). We collated data on the known and predicted distribution of Northeast Atlantic coral reefs, their protected areas, and fishing effort. We modelled the effects of ocean acidification on aragonite saturation to examine whether existing protected areas will ensure adequate protection for cold-water coral reefs under four possible future scenarios across two models. The best-case scenario suggests only minor impacts of ocean acidification, and that trawling remains the main threat to these reefs. However, in the worst-case scenario, by 2060, over 85% of these reefs are expected to be exposed to corrosive waters. We argue that unmanaged pressures such as ocean acidification and global warming should be incorporated into marine management decisions, with a focus on the protection of cold-water coral reefs to ensure long-term survival of these habitats. A similar approach could be taken for other iconic marine habitats in the face of climate change.