bluuebunny/crossref_metadata_2025 huggingface dataset:
Differentiated Instruction: A Culturally-Congruent Practice
Authors: Inglebret Ella , Banks-Joseph Susan Rae , Pavel Kaid'dub
Published: August 2016

A differentiated instructional approach is being advocated by leaders in education for meeting the needs of learners from diverse backgrounds who demonstrate varying abilities, strengths, and interests. Differentiated instruction (DI) is not a new idea and has a long, rich history of use in Native communities. This article describes the components of DI derived from a three-year curriculum design project, Honoring Tribal Legacies: An Epic Journey of Healing (CHiXapkaid, Inglebret, & Wood, 2014a, 2014b), sponsored by the National Park Service. As part of this project, PreK-12 curriculum materials were designed in a collaborative effort involving tribal and non-tribal educators including a speech-language pathologist (SLP), tribal elders, and representatives of a range of disciplines. The curriculum materials were analyzed to identify underlying themes and associated educational and intervention strategies. Overall, results of this analysis demonstrate how a DI approach aligns with incorporating tribal perspectives into the content, processes, and products of elementary and secondary level curriculum. As members of educational teams, SLPs can play an active role in working with teachers to use culturally-based DI. In this way, we can foster an educational environment that enhances students' beliefs in their capacities to comprehend, learn about, and become active participants in the world around them. To illustrate this, we end with the perspective of Kaid'dub Pavel, a ninth grade student with a profound, bilateral hearing loss and a cochlear implant. Kaid'dub shares his insights into DI, as it relates to his traditional cultural education.
60 GHz 5‐bit digital controlled phase shifter in a digital 40 nm CMOS technology without ultra‐thick metals
Authors: Gao H. , Ying K. , Matters‐Kammerer M.K. , Harpe P. , Wang B. , Liu B. , Serdijn W.A. , Baltus P.G.M.
Published: August 2016

A 5‐bit digital controlled switch‐type passive phase shifter realised in a 40 nm digital CMOS technology without ultra‐thick metals for the 60 GHz Industrial, Scientific and Medical (ISM) band is presented. A patterned shielding with electromagnetic bandgap structure and a stacked metals method to increase the on‐chip inductor quality factor are proposed. To reduce the insertion loss from the transistors, the transistor switches are implemented with a body–source connection. For all 32 states, the minimum phase error is 1.5°, and the maximum phase error is 6.8°. The measured insertion loss is −20.9 ± 1 dB including pad loss at 60 GHz and the return loss is >10 dB over 57–64 GHz. The total chip size is 0.24 mm2 with 0 mW DC power consumption.
Multi‐label meta‐learning approach for the automatic configuration of classifier ensembles
Authors: Nascimento D.S.C. , Canuto A.M.P. , Coelho A.L.V.
Published: August 2016

The task of automatically configuring classifier ensembles as a multi‐label classification problem and investigate a meta‐learning approach to cope with it is modelled. More specifically, the role of the meta‐learner is to recommend the types of components that should comprise the best ensemble model for coping with a given classification problem. Since different component types may be appropriate for each case, advocate that modelling the meta‐learner's task as a multi‐label classification problem can be useful. To systematically validate this hypothesis and the results confirm the suitability of configuring classifier ensembles via multi‐label meta‐learners.
A comparative study of LaBr3(Ce3+) and CeBr3 based gamma-ray spectrometers for planetary remote sensing applications
Authors: Kozyrev A. , Mitrofanov I. , Owens A. , Quarati F. , Benkhoff J. , Bakhtin B. , Fedosov F. , Golovin D. , Litvak M. , Malakhov A. , Mokrousov M. , Nuzhdin I. , Sanin A. , Tretyakov V. , Vostrukhin A. , Timoshenko G. , Shvetsov V. , Granja C. , Slavicek T. , Pospisil S.
Published: August 2016

The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA’s BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr3(Ce3+) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr3 became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr3 crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr3(Ce3+) and CeBr3 provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr3 is a more attractive system than LaBr3(Ce3+) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr3 now forms the central gamma-ray detection element on the MPO spacecraft.
Little Earth Experiment: An instrument to model planetary cores
Authors: Aujogue Kélig , Pothérat Alban , Bates Ian , Debray François , Sreenivasan Binod
Published: August 2016

In this paper, we present a new experimental facility, Little Earth Experiment, designed to study the hydrodynamics of liquid planetary cores. The main novelty of this apparatus is that a transparent electrically conducting electrolyte is subject to extremely high magnetic fields (up to 10 T) to produce electromagnetic effects comparable to those produced by moderate magnetic fields in planetary cores. This technique makes it possible to visualise for the first time the coupling between the principal forces in a convection-driven dynamo by means of Particle Image Velocimetry (PIV) in a geometry relevant to planets. We first present the technology that enables us to generate these forces and implement PIV in a high magnetic field environment. We then show that the magnetic field drastically changes the structure of convective plumes in a configuration relevant to the tangent cylinder region of the Earth’s core.
Crystallization of glass-forming liquids: Specific surface energy
Authors: Schmelzer Jürn W. P. , Abyzov Alexander S.
Published: August 2016

A generalization of the Stefan-Skapski-Turnbull relation for the melt-crystal specific interfacial energy is developed in terms of the generalized Gibbs approach extending its standard formulation to thermodynamic non-equilibrium states. With respect to crystal nucleation, this relation is required in order to determine the parameters of the critical crystal clusters being a prerequisite for the computation of the work of critical cluster formation. As one of its consequences, a relation for the dependence of the specific surface energy of critical clusters on temperature and pressure is derived applicable for small and moderate deviations from liquid-crystal macroscopic equilibrium states. Employing the Stefan-Skapski-Turnbull relation, general expressions for the size and the work of formation of critical crystal clusters are formulated. The resulting expressions are much more complex as compared to the respective relations obtained via the classical Gibbs theory. Latter relations are retained as limiting cases of these more general expressions for moderate undercoolings. By this reason, the formulated, here, general relations for the specification of the critical cluster size and the work of critical cluster formation give a key for an appropriate interpretation of a variety of crystallization phenomena occurring at large undercoolings which cannot be understood in terms of the Gibbs’ classical treatment.
Beneficial effect of post-deposition treatment in high-efficiency Cu(In,Ga)Se2 solar cells through reduced potential fluctuations
Authors: Jensen S. A. , Glynn S. , Kanevce A. , Dippo P. , Li J. V. , Levi D. H. , Kuciauskas D.
Published: August 2016

World-record power conversion efficiencies for Cu(In,Ga)Se2 (CIGS) solar cells have been achieved via a post-deposition treatment with alkaline metals, which increases the open-circuit voltage and fill factor. We explore the role of the potassium fluoride (KF) post-deposition treatment in CIGS by employing energy- and time-resolved photoluminescence spectroscopy and electrical characterization combined with numerical modeling. The bulk carrier lifetime is found to increase with post-deposition treatment from 255 ns to 388 ns, which is the longest charge carrier lifetime reported for CIGS, and within ∼40% of the radiative limit. We find evidence that the post-deposition treatment causes a decrease in the electronic potential fluctuations. These potential fluctuations have previously been shown to reduce the open-circuit voltage and the device efficiency in CIGS. Additionally, numerical simulations based on the measured carrier lifetimes and mobilities show a diffusion length of ∼10 μm, which is ∼4 times larger than the film thickness. Thus, carrier collection in the bulk is not a limiting factor for device efficiency. By considering differences in doping, bandgap, and potential fluctuations, we present a possible explanation for the voltage difference between KF-treated and untreated samples.
A topological proof of chaos for two nonlinear heterogeneous triopoly game models
Authors: Pireddu Marina
Published: August 2016

We rigorously prove the existence of chaotic dynamics for two nonlinear Cournot triopoly game models with heterogeneous players, for which in the existing literature the presence of complex phenomena and strange attractors has been shown via numerical simulations. In the first model that we analyze, costs are linear but the demand function is isoelastic, while, in the second model, the demand function is linear and production costs are quadratic. As concerns the decisional mechanisms adopted by the firms, in both models one firm adopts a myopic adjustment mechanism, considering the marginal profit of the last period; the second firm maximizes its own expected profit under the assumption that the competitors' production levels will not vary with respect to the previous period; the third firm acts adaptively, changing its output proportionally to the difference between its own output in the previous period and the naive expectation value. The topological method we employ in our analysis is the so-called “Stretching Along the Paths” technique, based on the Poincaré-Miranda Theorem and the properties of the cutting surfaces, which allows to prove the existence of a semi-conjugacy between the system under consideration and the Bernoulli shift, so that the former inherits from the latter several crucial chaotic features, among which a positive topological entropy.
Analysis techniques for diagnosing runaway ion distributions in the reversed field pinch
Authors: Kim J. , Anderson J. K. , Capecchi W. , Bonofiglo P. J. , Sears S. H.
Published: August 2016

An advanced neutral particle analyzer (ANPA) on the Madison Symmetric Torus measures deuterium ions of energy ranges 8-45 keV with an energy resolution of 2-4 keV and time resolution of 10 μs. Three different experimental configurations measure distinct portions of the naturally occurring fast ion distributions: fast ions moving parallel, anti-parallel, or perpendicular to the plasma current. On a radial-facing port, fast ions moving perpendicular to the current have the necessary pitch to be measured by the ANPA. With the diagnostic positioned on a tangent line through the plasma core, a chord integration over fast ion density, background neutral density, and local appropriate pitch defines the measured sample. The plasma current can be reversed to measure anti-parallel fast ions in the same configuration. Comparisons of energy distributions for the three configurations show an anisotropic fast ion distribution favoring high pitch ions.
Electrodeposited thin FeCo films with highly thermal stable properties in high frequency range obtained by annealing in a strong magnetic field
Authors: Zong B. Y. , Phuoc N. N. , Wu Y. P. , Ho P. , Yang Y. , Li Z. W.
Published: August 2016

The preparation of thin ferromagnetic films with thermally stable properties in the high frequency gigahertz range is crucial for applications in different advanced devices. However, it is a challenge to attain such films as the mechanism and correlation between the crystallographic structure and dynamic magnetic properties remain unclear. Herein, through an appropriate annealing process involving a temperature of 510–580 K and an applied strong magnetic field of 10 kOe along the easy-axis of electrodeposited FeCo films, magnetic properties of the films (300–450 nm) in the gigahertz range are significantly improved. Typically, the magnetic soft nanofilms display highly stable dynamic microwave properties from room temperature to 420 K, even in the presence of a high frequency of ∼1.5 GHz and a large magnetic permeability of ∼460 (the maximum value in real part). The origin of the high thermal stability is attributed to the recrystallized uniformity in crystalline orientations and larger particle sizes after the annealing, which leads to slightly increased anisotropy, stress, Curie temperature, and difference in the magnetic coercivity between the easy and hard axes for the crystalline films, thus giving rise to the steady static magnetic properties (e.g., magnetic moment of 2.02–2.05 T) against environmental temperature fluctuation. This is in contrast to conventional as-prepared thin films without annealing or annealed in a transverse applied field. This method can be applied to other ferromagnetic films to improve their thermal stability for the utilization in various high frequency devices.
Control and automation of the Pegasus multi-point Thomson scattering system
Authors: Bodner G. M. , Bongard M. W. , Fonck R. J. , Reusch J. A. , Rodriguez Sanchez C. , Schlossberg D. J.
Published: August 2016

A new control system for the Pegasus Thomson scattering diagnostic has recently been deployed to automate the laser operation, data collection process, and interface with the system-wide Pegasus control code. Automation has been extended to areas outside of data collection, such as manipulation of beamline cameras and remotely controlled turning mirror actuators to enable intra-shot beam alignment. Additionally, the system has been upgraded with a set of fast (∼1 ms) mechanical shutters to mitigate contamination from background light. Modification and automation of the Thomson system have improved both data quality and diagnostic reliability.
Bayesian tomography and integrated data analysis in fusion diagnostics
Authors: Li Dong , Dong Y. B. , Deng Wei , Shi Z. B. , Fu B. Z. , Gao J. M. , Wang T. B. , Zhou Yan , Liu Yi , Yang Q. W. , Duan X. R.
Published: August 2016

In this article, a Bayesian tomography method using non-stationary Gaussian process for a prior has been introduced. The Bayesian formalism allows quantities which bear uncertainty to be expressed in the probabilistic form so that the uncertainty of a final solution can be fully resolved from the confidence interval of a posterior probability. Moreover, a consistency check of that solution can be performed by checking whether the misfits between predicted and measured data are reasonably within an assumed data error. In particular, the accuracy of reconstructions is significantly improved by using the non-stationary Gaussian process that can adapt to the varying smoothness of emission distribution. The implementation of this method to a soft X-ray diagnostics on HL-2A has been used to explore relevant physics in equilibrium and MHD instability modes. This project is carried out within a large size inference framework, aiming at an integrated analysis of heterogeneous diagnostics.
The radio-frequency fluctuation effect on the floating harmonic method
Authors: Lee Jaewon , Kim Kyung-Hyun , Kim Dong-Hwan , Chung Chin-Wook
Published: August 2016

The radio-frequency (RF) plasma diagnostics with an electrical probe facing a challenge, because the RF fluctuation oscillates the plasma potential and distorts the current-voltage (I-V) curve. As Langmuir probe is widely used in plasma diagnostics, many researchers have been studying the effect of RF fluctuation on probe and compensation methods. On the other hand, there have not been enough studies on the fluctuation effect on the floating harmonic method. Therefore, we investigated the impact of RF fluctuation on the floating harmonic method theoretically and experimentally. When the electrons are in ideal Maxwellian distribution, the floating potential is negatively shifted by the RF fluctuation, but the fluctuation does not distort I-V curve around the floating potential. However, in practical plasmas, the I-V curve and their harmonic components are distorted. This RF fluctuation effect becomes more significant in a low density plasma with a high impedance sheath. The second harmonic current decreases with the RF fluctuation while the first harmonic current is merely affected. Therefore, the electron temperatures measured with the floating harmonic method under low density plasma with uncompensated probe are overestimated than the results obtained with the compensated probe.
A new H2+ source: Conceptual study and experimental test of an upgraded version of the VIS—Versatile ion source
Authors: Castro G. , Torrisi G. , Celona L. , Mascali D. , Neri L. , Sorbello G. , Leonardi O. , Patti G. , Castorina G. , Gammino S.
Published: August 2016

The versatile ion source is an off-resonance microwave discharge ion source which produces a slightly overdense plasma at 2.45 GHz of pumping wave frequency extracting more than 60 mA proton beams and 50 mA He+ beams. DAEδALUS and IsoDAR experiments require high intensities for H2+ beams to be accelerated by high power cyclotrons for neutrinos generation. In order to fulfill the new requirements, a new plasma chamber and injection system has been designed and manufactured for increasing the H2+ beam intensity. In this paper the studies for the increasing of the H2+/p ratio and for the design of the new plasma chamber and injection system will be shown and discussed together with the experimental tests carried out at Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud (INFN-LNS) and at Best Cyclotron Systems test-bench in Vancouver, Canada.
Simulation of temperature dependent dielectric breakdown in n+-polySi/SiO2/n-6H-SiC structures during Poole-Frenkel stress at positive gate bias
Authors: Samanta Piyas , Mandal Krishna C.
Published: August 2016

We present for the first time a thorough investigation of trapped-hole induced gate oxide deterioration and simulation results of time-dependent dielectric breakdown (TDDB) of thin (7–25 nm) silicon dioxide (SiO2) films thermally grown on (0 0 0 1) silicon (Si) face of n-type 6H-silicon carbide (n-6H-SiC). Gate oxide reliability was studied during both constant voltage and current stress with positive bias on the degenerately doped n-type poly-crystalline silicon (n+-polySi) gate at a wide range of temperatures between 27 and 225 °C. The gate leakage current was identified as the Poole-Frenkel (PF) emission of electrons trapped at an energy 0.92 eV below the SiO2 conduction band. Holes were generated in the n+-polySi anode material as well as in the oxide bulk via band-to-band ionization depending on the film thickness tox and the energy of the hot-electrons (emitted via PF mechanism) during their transport through oxide films at oxide electric fields Eox ranging from 5 to 10 MV/cm. Our simulated time-to-breakdown (tBD) results are in excellent agreement with those obtained from time consuming TDDB measurements. It is observed that irrespective of stress temperatures, the tBD values estimated in the field range between 5 and 9 MV/cm better fit to reciprocal field (1/E) model for the thickness range studied here. Furthermore, for a 10 year projected device lifetime, a good reliability margin of safe operating field from 8.5 to 7.5 MV/cm for 7 nm and 8.1 to 6.9 MV/cm for 25 nm thick SiO2 was observed between 27 and 225 °C.
Parameter space of experimental chaotic circuits with high-precision control parameters
Authors: de Sousa Francisco F. G. , Rubinger Rero M. , Sartorelli José C. , Albuquerque Holokx A. , Baptista Murilo S.
Published: August 2016

We report high-resolution measurements that experimentally confirm a spiral cascade structure and a scaling relationship of shrimps in the Chua's circuit. Circuits constructed using this component allow for a comprehensive characterization of the circuit behaviors through high resolution parameter spaces. To illustrate the power of our technological development for the creation and the study of chaotic circuits, we constructed a Chua circuit and study its high resolution parameter space. The reliability and stability of the designed component allowed us to obtain data for long periods of time (∼21 weeks), a data set from which an accurate estimation of Lyapunov exponents for the circuit characterization was possible. Moreover, this data, rigorously characterized by the Lyapunov exponents, allows us to reassure experimentally that the shrimps, stable islands embedded in a domain of chaos in the parameter spaces, can be observed in the laboratory. Finally, we confirm that their sizes decay exponentially with the period of the attractor, a result expected to be found in maps of the quadratic family.
A high resolution IR/visible imaging system for the W7-X limiter
Authors: Wurden G. A. , Stephey L. A. , Biedermann C. , Jakubowski M. W. , Dunn J. P. , Gamradt M. ,   W7-X Team
Published: August 2016

A high-resolution imaging system, consisting of megapixel mid-IR and visible cameras along the same line of sight, has been prepared for the new W7-X stellarator and was operated during Operational Period 1.1 to view one of the five inboard graphite limiters. The radial line of sight, through a large diameter (184 mm clear aperture) uncoated sapphire window, couples a direct viewing 1344 × 784 pixel FLIR SC8303HD camera. A germanium beam-splitter sends visible light to a 1024 × 1024 pixel Allied Vision Technologies Prosilica GX1050 color camera. Both achieve sub-millimeter resolution on the 161 mm wide, inertially cooled, segmented graphite tiles. The IR and visible cameras are controlled via optical fibers over full Camera Link and dual GigE Ethernet (2 Gbit/s data rates) interfaces, respectively. While they are mounted outside the cryostat at a distance of 3.2 m from the limiter, they are close to a large magnetic trim coil and require soft iron shielding. We have taken IR data at 125 Hz to 1.25 kHz frame rates and seen that surface temperature increases in excess of 350 °C, especially on leading edges or defect hot spots. The IR camera sees heat-load stripe patterns on the limiter and has been used to infer limiter power fluxes (∼1–4.5 MW/m2), during the ECRH heating phase. IR images have also been used calorimetrically between shots to measure equilibrated bulk tile temperature, and hence tile energy inputs (in the range of 30 kJ/tile with 0.6 MW, 6 s heating pulses). Small UFO’s can be seen and tracked by the FLIR camera in some discharges. The calibrated visible color camera (100 Hz frame rate) has also been equipped with narrow band C-III and H-alpha filters, to compare with other diagnostics, and is used for absolute particle flux determination from the limiter surface. Sometimes, but not always, hot-spots in the IR are also seen to be bright in C-III light.
Characterization of the photocurrents generated by the laser of atomic force microscopes
Authors: Ji Yanfeng , Hui Fei , Shi Yuanyuan , Iglesias Vanessa , Lewis David , Niu Jiebin , Long Shibing , Liu Ming , Hofer Alexander , Frammelsberger Werner , Benstetter Guenther , Scheuermann Andrew , McIntyre Paul C. , Lanza Mario
Published: August 2016

The conductive atomic force microscope (CAFM) has become an essential tool for the nanoscale electronic characterization of many materials and devices. When studying photoactive samples, the laser used by the CAFM to detect the deflection of the cantilever can generate photocurrents that perturb the current signals collected, leading to unreliable characterization. In metal-coated semiconductor samples, this problem is further aggravated, and large currents above the nanometer range can be observed even without the application of any bias. Here we present the first characterization of the photocurrents introduced by the laser of the CAFM, and we quantify the amount of light arriving to the surface of the sample. The mechanisms for current collection when placing the CAFM tip on metal-coated photoactive samples are also analyzed in-depth. Finally, we successfully avoided the laser-induced perturbations using a two pass technique: the first scan collects the topography (laser ON) and the second collects the current (laser OFF). We also demonstrate that CAFMs without a laser (using a tuning fork for detecting the deflection of the tip) do not have this problem.
Multi-energy x-ray detector calibration for Te and impurity density (nZ) measurements of MCF plasmas
Authors: Maddox J. , Pablant N. , Efthimion P. , Delgado-Aparicio L. , Hill K. W. , Bitter M. , Reinke M. L. , Rissi M. , Donath T. , Luethi B. , Stratton B.
Published: August 2016

Soft x-ray detection with the new “multi-energy” PILATUS3 detector systems holds promise as a magnetically confined fusion (MCF) plasma diagnostic for ITER and beyond. The measured x-ray brightness can be used to determine impurity concentrations, electron temperatures, ne2Zeff products, and to probe the electron energy distribution. However, in order to be effective, these detectors which are really large arrays of detectors with photon energy gating capabilities must be precisely calibrated for each pixel. The energy-dependence of the detector response of the multi-energy PILATUS3 system with 100 K pixels has been measured at Dectris Laboratory. X-rays emitted from a tube under high voltage bombard various elements such that they emit x-ray lines from Zr-Lα to Ag-Kα between 1.8 and 22.16 keV. Each pixel on the PILATUS3 can be set to a minimum energy threshold in the range from 1.6 to 25 keV. This feature allows a single detector to be sensitive to a variety of x-ray energies, so that it is possible to sample the energy distribution of the x-ray continuum and line-emission. PILATUS3 can be configured for 1D or 2D imaging of MCF plasmas with typical spatial energy and temporal resolution of 1 cm, 0.6 keV, and 5 ms, respectively.
On stable solitons and interactions of the generalized Gross-Pitaevskii equation with PT- and non-PT-symmetric potentials
Authors: Yan Zhenya , Chen Yong , Wen Zichao
Published: August 2016

We report the bright solitons of the generalized Gross-Pitaevskii (GP) equation with some types of physically relevant parity-time- (PT-) and non-PT-symmetric potentials. We find that the constant momentum coefficient Γ can modulate the linear stability and complicated transverse power-flows (not always from the gain toward loss) of nonlinear modes. However, the varying momentum coefficient Γ(x) can modulate both unbroken linear PT-symmetric phases and stability of nonlinear modes. Particularly, the nonlinearity can excite the unstable linear mode (i.e., broken linear PT-symmetric phase) to stable nonlinear modes. Moreover, we also find stable bright solitons in the presence of non-PT-symmetric harmonic-Gaussian potential. The interactions of two bright solitons are also illustrated in PT-symmetric potentials. Finally, we consider nonlinear modes and transverse power-flows in the three-dimensional (3D) GP equation with the generalized PT-symmetric Scarff-II potential.
Description and control of dissociation channels in gas-phase protein complexes
Authors: Thachuk Mark , Fegan Sarah K. , Raheem Nigare
Published: August 2016

Using molecular dynamics simulations of a coarse-grained model of the charged apo-hemoglobin protein complex, this work expands upon our initial report [S. K. Fegan and M. Thachuk, J. Am. Soc. Mass Spectrom. 25, 722–728 (2014)] about control of dissociation channels in the gas phase using specially designed charge tags. Employing a charge hopping algorithm and a range of temperatures, a variety of dissociation channels are found for activated gas-phase protein complexes. At low temperatures, a single monomer unfolds and becomes charge enriched. At higher temperatures, two additional channels open: (i) two monomers unfold and charge enrich and (ii) two monomers compete for unfolding with one eventually dominating and the other reattaching to the complex. At even higher temperatures, other more complex dissociation channels open with three or more monomers competing for unfolding. A model charge tag with five sites is specially designed to either attract or exclude charges. By attaching this tag to the N-terminus of specific monomers, the unfolding of those monomers can be decidedly enhanced or suppressed. In other words, using charge tags to direct the motion of charges in a protein complex provides a mechanism for controlling dissociation. This technique could be used in mass spectrometry experiments to direct forces at specific attachment points in a protein complex, and hence increase the diversity of product channels available for quantitative analysis. In turn, this could provide insight into the function of the protein complex in its native biological environment. From a dynamics perspective, this system provides an interesting example of cooperative behaviour involving motions with differing time scales.
Photoinduced diffusion molecular transport
Authors: Rozenbaum Viktor M. , Dekhtyar Marina L. , Lin Sheng Hsien , Trakhtenberg Leonid I.
Published: August 2016

We consider a Brownian photomotor, namely, the directed motion of a nanoparticle in an asymmetric periodic potential under the action of periodic rectangular resonant laser pulses which cause charge redistribution in the particle. Based on the kinetics for the photoinduced electron redistribution between two or three energy levels of the particle, the time dependence of its potential energy is derived and the average directed velocity is calculated in the high-temperature approximation (when the spatial amplitude of potential energy fluctuations is small relative to the thermal energy). The thus developed theory of photoinduced molecular transport appears applicable not only to conventional dichotomous Brownian motors (with only two possible potential profiles) but also to a much wider variety of molecular nanomachines. The distinction between the realistic time dependence of the potential energy and that for a dichotomous process (a step function) is represented in terms of relaxation times (they can differ on the time intervals of the dichotomous process). As shown, a Brownian photomotor has the maximum average directed velocity at (i) large laser pulse intensities (resulting in short relaxation times on laser-on intervals) and (ii) excited state lifetimes long enough to permit efficient photoexcitation but still much shorter than laser-off intervals. A Brownian photomotor with optimized parameters is exemplified by a cylindrically shaped semiconductor nanocluster which moves directly along a polar substrate due to periodically photoinduced dipole moment (caused by the repetitive excited electron transitions to a non-resonant level of the nanocylinder surface impurity).
Poisson-Boltzmann study of the effective electrostatic interaction between colloids at an electrolyte interface
Authors: Majee Arghya , Bier Markus , Dietrich S.
Published: August 2016

The effective electrostatic interaction between a pair of colloids, both of them located close to each other at an electrolyte interface, is studied by employing the full, nonlinear Poisson-Boltzmann (PB) theory within classical density functional theory. Using a simplified yet appropriate model, all contributions to the effective interaction are obtained exactly, albeit numerically. The comparison between our results and those obtained within linearized PB theory reveals that the latter overestimates these contributions significantly at short inter-particle separations. Whereas the surface contributions to the linear and the nonlinear PB results differ only quantitatively, the line contributions show qualitative differences at short separations. Moreover, a dependence of the line contribution on the solvation properties of the two adjacent fluids is found, which is absent within the linear theory. Our results are expected to enrich the understanding of effective interfacial interactions between colloids.
Coupling of electrostatic ion cyclotron and ion acoustic waves in the solar wind
Authors: Sreeraj T. , Singh S. V. , Lakhina G. S.
Published: August 2016

The coupling of electrostatic ion cyclotron and ion acoustic waves is examined in three component magnetized plasma consisting of electrons, protons, and alpha particles. In the theoretical model relevant to solar wind plasma, electrons are assumed to be superthermal with kappa distribution and protons as well as alpha particles follow the fluid dynamical equations. A general linear dispersion relation is derived for such a plasma system which is analyzed both analytically and numerically. For parallel propagation, electrostatic ion cyclotron (proton and helium cyclotron) and ion acoustic (slow and fast) modes are decoupled. For oblique propagation, coupling between the cyclotron and acoustic modes occurs. Furthermore, when the angle of propagation is increased, the separation between acoustic and cyclotron modes increases which is an indication of weaker coupling at large angle of propagation. For perpendicular propagation, only cyclotron modes are observed. The effect of various parameters such as number density and temperature of alpha particles and superthermality on dispersion characteristics is examined in details. The coupling between various modes occurs for small values of wavenumber.
PIC simulation of compressive and rarefactive dust ion-acoustic solitary waves
Authors: Li Zhong-Zheng , Zhang Heng , Hong Xue-Ren , Gao Dong-Ning , Zhang Jie , Duan Wen-Shan , Yang Lei
Published: August 2016

The nonlinear propagations of dust ion-acoustic solitary waves in a collisionless four-component unmagnetized dusty plasma system containing nonextensive electrons, inertial negative ions, Maxwellian positive ions, and negatively charged static dust grains have been investigated by the particle-in-cell method. By comparing the simulation results with those obtained from the traditional reductive perturbation method, it is observed that the rarefactive KdV solitons propagate stably at a low amplitude, and when the amplitude is increased, the prime wave form evolves and then gradually breaks into several small amplitude solitary waves near the tail of soliton structure. The compressive KdV solitons propagate unstably and oscillation arises near the tail of soliton structure. The finite amplitude rarefactive and compressive Gardner solitons seem to propagate stably.
Deposition of a-C:H films on inner surface of high-aspect-ratio microchannel
Authors: Hirata Yuki , Choi Junho
Published: August 2016

Hydrogenated amorphous carbon (a-C:H) films were prepared on inner surface of 100-μm-width microchannel by using a bipolar-type plasma based ion implantation and deposition. The microchannel was fabricated using a silicon plate, and two kinds of microchannels were prepared, namely, with a bottom layer (open at one end) and without a bottom layer (open at both ends). The distribution of thickness and hardness of films was evaluated by SEM and nanoindentation measurements, respectively, and the microstructures of films were evaluated by Raman spectroscopy. Furthermore, the behavior of ions and radicals was analyzed simultaneously by combining the calculation methods of Particle-In-Cell/Monte Carlo Collision and Direct Simulation Monte Carlo to investigate the coating mechanism for the microchannel. It was found that the film thickness decreased as the depth of the coating position increased in the microchannels where it is open at one end. The uniformity of the film thickness improved by increasing the negative pulse voltage because ions can arrive at the deeper part of the microchannel. In addition, the hardness increased as the depth of the coating position increased. This is because the radicals do not arrive at the deeper part of the microchannel, and the incident proportion of ions relative to that of radicals increases, resulting in a high hardness due to the amorphization of the film. The opening area of the microchannel where the aspect ratio is very small, radicals dominate the incident flux, whereas ions prevail over radicals above an aspect ratio of about 7.5. On the other hand, in the microchannels that are open at both ends, there were great improvements in uniformity of the film thickness, hardness, and the film structure. The a-C:H films were successfully deposited on the entire inner surface of a microchannel with an aspect ratio of 20.
Quantitative determination of optical and recombination losses in thin-film photovoltaic devices based on external quantum efficiency analysis
Authors: Nakane Akihiro , Tampo Hitoshi , Tamakoshi Masato , Fujimoto Shohei , Kim Kang Min , Kim Shinho , Shibata Hajime , Niki Shigeru , Fujiwara Hiroyuki
Published: August 2016

In developing photovoltaic devices with high efficiencies, quantitative determination of the carrier loss is crucial. In conventional solar-cell characterization techniques, however, photocurrent reduction originating from parasitic light absorption and carrier recombination within the light absorber cannot be assessed easily. Here, we develop a general analysis scheme in which the optical and recombination losses in submicron-textured solar cells are evaluated systematically from external quantum efficiency (EQE) spectra. In this method, the optical absorption in solar cells is first deduced by imposing the anti-reflection condition in the calculation of the absorptance spectrum, and the carrier extraction from the light absorber layer is then modeled by considering a carrier collection length from the absorber interface. Our analysis method is appropriate for a wide variety of photovoltaic devices, including kesterite solar cells [Cu2ZnSnSe4, Cu2ZnSnS4, and Cu2ZnSn(S,Se)4], zincblende CdTe solar cells, and hybrid perovskite (CH3NH3PbI3) solar cells, and provides excellent fitting to numerous EQE spectra reported earlier. Based on the results obtained from our EQE analyses, we discuss the effects of parasitic absorption and carrier recombination in different types of solar cells.
A flow cell for measuring X-ray Compton scattering of liquid at temperatures up to 623 K and pressures up to 20 MPa
Authors: Ono Takumi , Watanabe Masaru , Sato Yoshiyuki , Inomata Hiroshi , Nakahara Koichi , Itou Masayoshi , Sakurai Yoshiharu
Published: August 2016

A flow-type cell was developed for measuring Compton scattering spectra of heat-sensitive aqueous solution. Compton scattering spectra of water and ethanol were measured in the region from ambient conditions to 623 K and 20 MPa. Compton profiles derived from measurement with the flow-type cell were comparable with those in the literature. Results obtained from the flow-type cell showed that delocalization of electronic charge density of water and ethanol at high temperatures occurred. Delocalization of the electronic charge density of ethanol was greater than that of water at high temperature, which is consistent with the prior works that use proton NMR chemical shifts to describe hydrogen bonding.
Magnetism and electronic phase transitions in monoclinic transition metal dichalcogenides with transition metal atoms embedded
Authors: Lin Xianqing , Ni Jun
Published: August 2016

First-principles calculations have been performed to study the energetic, electronic, and magnetic properties of substitutional 3d transition metal dopants in monoclinic transition metal dichalcogenides (TMDs) as topological insulators (1T′-MX2 with M = (Mo, W) and X = (S, Se)). We find various favorite features in these doped systems to introduce magnetism and other desirable electronic properties: (i) The Mn embedded monoclinic TMDs are magnetic, and the doped 1T′-MoS2 still maintains the semiconducting character with high concentration of Mn, while an electronic phase transition occurs in other Mn doped monoclinic TMDs with an increasing concentration of Mn. Two Mn dopants prefer the ferromagnetic coupling except for substitution of the nearest Mo atoms in 1T′-MoS2, and the strength of exchange interaction shows anisotropic behavior with dopants along one Mo zigzag chain having much stronger coupling. (ii) The substitutional V is a promising hole dopant, which causes little change to the energy dispersion around the conduction and valence band edges in most systems. In contrast, parts of the conduction band drop for the electron dopants Co and Ni due to the large structural distortion. Moreover, closing band gaps of the host materials are observed with increasing carrier concentration. (iii) Single Fe dopant has a magnetic moment, but it also dopes electrons. When two Fe dopants have a small distance, the systems turn into nonmagnetic semiconductors. (iv) The formation energies of all dopants are much lower than those in hexagonal TMDs and are all negative in certain growth conditions, suggesting possible realization of the predicted magnetism, electronic phase transitions as well as carrier doping in 1T′-MX2 based topological devices.
Finite time blowup of solutions to the nonlinear Schrödinger equation without gauge invariance
Authors: Fujiwara Kazumasa , Ozawa Tohru
Published: August 2016

A lifespan estimate and a condition of the initial data for finite time blowup for the nonlinear Schrödinger equation are presented from a view point of ordinary differential equation (ODE) mechanism.
An upgraded interferometer-polarimeter system for broadband fluctuation measurements
Authors: Parke E. , Ding W. X. , Duff J. , Brower D. L.
Published: August 2016

Measuring high-frequency fluctuations (above tearing mode frequencies) is important for diagnosing instabilities and transport phenomena. The Madison Symmetric Torus interferometer-polarimeter system has been upgraded to utilize improved planar-diode mixer technology. The new mixers reduce phase noise and allow more sensitive measurements of fluctuations at high frequency. Typical polarimeter rms phase noise values of 0.05°–0.07° are obtained with 400 kHz bandwidth. The low phase noise enables the resolution of fluctuations up to 250 kHz for polarimetry and 600 kHz for interferometry. The importance of probe beam alignment for polarimetry is also verified; previously reported tolerances of ≤0.1 mm displacement for equilibrium and tearing mode measurements minimize contamination due to spatial misalignment to within acceptable levels for chords near the magnetic axis.
Observation of hohlraum-wall motion with spectrally selective x-ray imaging at the National Ignition Facility
Authors: Izumi N. , Meezan N. B. , Divol L. , Hall G. N. , Barrios M. A. , Jones O. , Landen O. L. , Kroll J. J. , Vonhof S. A. , Nikroo A. , Jaquez J. , Bailey C. G. , Hardy C. M. , Ehrlich R. B. , Town R. P. J. , Bradley D. K. , Hinkel D. E. , Moody J. D.
Published: August 2016

The high fuel capsule compression required for indirect drive inertial confinement fusion requires careful control of the X-ray drive symmetry throughout the laser pulse. When the outer cone beams strike the hohlraum wall, the plasma ablated off the hohlraum wall expands into the hohlraum and can alter both the outer and inner cone beam propagations and hence the X-ray drive symmetry especially at the final stage of the drive pulse. To quantitatively understand the wall motion, we developed a new experimental technique which visualizes the expansion and stagnation of the hohlraum wall plasma. Details of the experiment and the technique of spectrally selective x-ray imaging are discussed.
Thermophysical properties of liquid Ni around the melting temperature from molecular dynamics simulation
Authors: Rozas R. E. , Demiraǧ A. D. , Toledo P. G. , Horbach J.
Published: August 2016

Thermophysical properties of liquid nickel (Ni) around the melting temperature are investigated by means of classical molecular dynamics (MD) simulation, using three different embedded atom method potentials to model the interactions between the Ni atoms. Melting temperature, enthalpy, static structure factor, self-diffusion coefficient, shear viscosity, and thermal diffusivity are compared to recent experimental results. Using ab initio MD simulation, we also determine the static structure factor and the mean-squared displacement at the experimental melting point. For most of the properties, excellent agreement is found between experiment and simulation, provided the comparison relative to the corresponding melting temperature. We discuss the validity of the Hansen-Verlet criterion for the static structure factor as well as the Stokes-Einstein relation between self-diffusion coefficient and shear viscosity. The thermal diffusivity is extracted from the autocorrelation function of a wavenumber-dependent temperature fluctuation variable.
Approximate explicit analytic solution of the Elenbaas-Heller equation
Authors: Liao Meng-Ran , Li Hui , Xia Wei-Dong
Published: August 2016

The Elenbaas-Heller equation describing the temperature field of a cylindrically symmetrical non-radiative electric arc has been solved, and approximate explicit analytic solutions are obtained. The radial distributions of the heat-flux potential and the electrical conductivity have been figured out briefly by using some special simplification techniques. The relations between both the core heat-flux potential and the electric field with the total arc current have also been given in several easy explicit formulas. Besides, the special voltage-ampere characteristic of electric arcs is explained intuitionally by a simple expression involving the Lambert W-function. The analyses also provide a preliminary estimation of the Joule heating per unit length, which has been verified in previous investigations. Helium arc is used to examine the theories, and the results agree well with the numerical computations.
Cherenkov detectors for spatial imaging applications using discrete-energy photons
Authors: Rose Paul B. , Erickson Anna S.
Published: August 2016

Cherenkov detectors can offer a significant advantage in spatial imaging applications when excellent timing response, low noise and cross talk, large area coverage, and the ability to operate in magnetic fields are required. We show that an array of Cherenkov detectors with crude energy resolution coupled with monochromatic photons resulting from a low-energy nuclear reaction can be used to produce a sharp image of material while providing large and inexpensive detector coverage. The analysis of the detector response to relative transmission of photons with various energies allows for reconstruction of material's effective atomic number further aiding in high-Z material identification.