Width Narrowing Research Articles

Study on incoherent scatter theory of high density dusty plasma

Incoherent scatter radar is one of the most important detection instruments of the space plasma. But because of the low dust density in natural space plasma, the contribution of charged dust to incoherent scatter spectrum can be completely ignored, therefore the incoherent scattering theory has not appeared in dusty plasma. In the solid rocket plume, the propellant combustion can form a large number of nanometer- and micronmeter-sized dusty particles, and produce a high electron density from high temperature ionization, which makes considerable contributionto charged dusty particles with the high density. Therefore, we develop the incoherent scattering theory of dusty plasma in order to calculate the scattering characteristics of high density dusty plasma produced by rocket plume, for example. The theoretical model including electrons, ions and dusty particles is established by combining effects of charged dusty particles. The incoherent scatter spectral lines of ion resonance region and dust resonance regionare calculated. The effects of dusty particle radius, temperature and density on spectral line structure are discussed. With the increases of dusty particle radius and density, the amplitude of power spectrum increases. With the increase of dust temperature, the amplitude of power spectrum decreases. In the dust resonance region, the control mechanism of dust in spectrum is similar to that of the ions. With the increase of particle size (mass) and decrease of the temperature, the spectrum width narrows, and amplitude and area increase with the increase of density. But in the ion resonance region, the dust control mechanism is completely different, and the influence of the dust on ion line is in the way of attracting ions. So with the increase of dust density, ion line characteristics do not show that the area increases, and dust controls ions by adjusting the Debye radius or electrostatic shielding ball size. By comparing the ion lines with and without dust under the same parameters conditions, the amplitude of the ion line with dust is much larger than that without dust, and the resonance frequency of the ion line is greatly changed. With the dust particles of a relatively high density, one can enhance the ion line, hence the incoherent scattering phenomenon can be more easily observed in rocket plume. On the other hand, due to significant changes of frequency and amplitude in the ion line spectrum, the incoherent scattering inversion method based on the traditional theory will cause a large error in the inversion parameter, even a failure of parameter retrieval. The incoherent scattering theory and relevant physical laws of dusty plasma are presented, which are of great significance for establishing the incoherent scattering theory system and studying the rocket plume parameters.

Hybrid electroluminescent device based on MEH-PPV and ZnO

Hybird organic/inorganic electroluminescent device based on the structure of glass/ITO/PEDOT:PSS/MEH-PPV/ZnO/ZnO submicrorods/Al has been manufactured. Spin coating has been used to deposit both PEDOT:PSS and MEH-PPV. Two-step process has been used to synthesis ZnO submicrorods, namely, spin coating and chemical bath deposition. Changing the dimensions of the ZnO submicrorods in this layer structure has been investigated to improve the performance of the organic/inorganic electroluminescence device. Such layer structure provides electroluminescence with narrow emission bands due to a high gain with this structure. X-ray diffraction patterns and scanning electron microscope images show that ZnO submicrorods have hexagon structure. Current-voltage curve for the structure has been reported. Electroluminescence curves (electroluminescence intensity versus wavelength) at different bias voltages have been presented and these results show narrowing in full width at half maximum in the spectra at high current density compared to photoluminescence excitation. The narrowing in the spectrum has been explained.

Field‐aligned currents in Saturn's magnetosphere: Local time dependence of southern summer currents in the dawn sector between midnight and noon

AbstractWe examine and compare the magnetic field perturbations associated with field‐aligned ionosphere‐magnetosphere coupling currents at Saturn, observed by the Cassini spacecraft during two sequences of highly inclined orbits in 2006/2007 and 2008 under late southern summer conditions. These sequences explore the southern currents in the dawn‐noon and midnight sectors, respectively, thus allowing investigation of possible origins of the local time (LT) asymmetry in auroral Saturn kilometric radiation (SKR) emissions, which peak in power at ~8 h LT in the dawn‐noon sector. We first show that the dawn‐noon field data generally have the same four‐sheet current structure as found previously in the midnight data and that both are similarly modulated by “planetary period oscillation” (PPO) currents. We then separate the averaged PPO‐independent (e.g., subcorotation) and PPO‐related currents for both LT sectors by using the current system symmetry properties. Surprisingly, we find that the PPO‐independent currents are essentially identical within uncertainties in the dawn‐dusk and midnight sectors, thus providing no explanation for the LT dependence of the SKR emissions. The main PPO‐related currents are, however, found to be slightly stronger and narrower in latitudinal width at dawn‐noon than at midnight, leading to estimated precipitating electron powers, and hence emissions, that are on average a factor of ~1.3 larger at dawn‐noon than at midnight, inadequate to account for the observed LT asymmetry in SKR power by a factor of ~2.7. Some other factors must also be involved, such as a LT asymmetry in the hot magnetospheric auroral source electron population.

Echolocating Big Brown Bats, Eptesicus fuscus, Modulate Pulse Intervals to Overcome Range Ambiguity in Cluttered Surroundings.

Big brown bats (Eptesicus fuscus) emit trains of brief, wideband frequency-modulated (FM) echolocation sounds and use echoes of these sounds to orient, find insects, and guide flight through vegetation. They are observed to emit sounds that alternate between short and long inter-pulse intervals (IPIs), forming sonar sound groups. The occurrence of these strobe groups has been linked to flight in cluttered acoustic environments, but how exactly bats use sonar sound groups to orient and navigate is still a mystery. Here, the production of sound groups during clutter navigation was examined. Controlled flight experiments were conducted where the proximity of the nearest obstacles was systematically decreased while the extended scene was kept constant. Four bats flew along a corridor of varying widths (100, 70, and 40 cm) bounded by rows of vertically hanging plastic chains while in-flight echolocation calls were recorded. Bats shortened their IPIs for more rapid spatial sampling and also grouped their sounds more tightly when flying in narrower corridors. Bats emitted echolocation calls with progressively shorter IPIs over the course of a flight, and began their flights by emitting shorter starting IPI calls when clutter was denser. The percentage of sound groups containing 3 or more calls increased with increasing clutter proximity. Moreover, IPI sequences having internal structure become more pronounced when corridor width narrows. A novel metric for analyzing the temporal organization of sound sequences was developed, and the results indicate that the time interval between echolocation calls depends heavily on the preceding time interval. The occurrence of specific IPI patterns were dependent upon clutter, which suggests that sonar sound grouping may be an adaptive strategy for coping with pulse-echo ambiguity in cluttered surroundings.

Micro‐Optics for Photolithography

AbstractPhotolithography is the engine that empowered semiconductor industry to reduce the minimum feature size of the components of a microchip from some 50 microns in the 1960s to below 14 nanometers today. Diffractive and refractive micro‐optical components play a decisive role in modern photolithography systems, e.g. for laser line width narrowing, laser beam shaping (customized illumination), as phaseshift masks, for optical proximity correction, and for diffraction‐based overlay. Wafer‐based manufacturing of high‐quality micro‐optics and their importance for photolithography will be explained.

Au-Ag@Au Hollow Nanostructure with Enhanced Chemical Stability and Improved Photothermal Transduction Efficiency for Cancer Treatment.

Despite the fact that Au-Ag hollow nanoparticles (HNPs) have gained much attention as ablation agents for photothermal therapy, the instability of the Ag element limits their applications. Herein, excess Au atoms were deposited on the surface of a Au-Ag HNP by improving the reduction power of l-ascorbic acid (AA) and thereby preventing the reaction between HAuCl4 and the Ag element in the Au-Ag alloy nanostructure. Significantly, the obtained Au-Ag@Au HNPs show excellent chemical stability in an oxidative environment, together with remarkable increase in extinction peak intensity and obvious narrowing in peak width. Moreover, finite-difference time-domain (FDTD) was used to simulate the optical properties and electric field distribution of HNPs. The calculated results show that the proportion of absorption cross section in total extinction cross section increases with the improvement of Au content in HNP. As predicted by the theoretical calculation results, Au-Ag@Au nanocages (NCs) exhibit a photothermal transduction efficiency (η) as high as 36.5% at 808 nm, which is higher than that of Au-Ag NCs (31.2%). Irradiated by 808 nm laser at power densities of 1 W/cm(2), MCF-7 breast cancer cells incubated with PEGylated Au-Ag@Au NCs were seriously destroyed. Combined together, Au-Ag@Au HNPs with enhanced chemical stability and improved photothermal transduction efficiency show superior competitiveness as photothermal agents.

Micro‐Optics for Photolithography

AbstractPhotolithography is the engine that empowered semiconductor industry to reduce the minimum feature size of the components of a microchip from some 50 microns in the 1960s to below 14 nanometers today. Diffractive and refractive micro‐optical components play a decisive role in modern photolithography systems, e. g. for laser line width narrowing, laser beam shaping (customized illumination), as phase‐shift masks (PSM), for optical proximity correction (OPC), and for diffraction‐based overlay (DBO). Wafer‐based manufacturing of high‐quality micro‐optics and their importance for photolithography will be explained.

Second order discontinuous Galerkin scheme for compound natural channels with movable bed. Applications for the computation of rating curves

A new higher order 1D numerical scheme for the propagation of flood waves in compound channels with a movable bed is presented. The model equations are solved by means of an ADER Discontinuous Galerkin explicit scheme which can, in principle, reach any order of space–time accuracy. The higher order nature of the scheme allows the numerical coupling between flux and source terms appearing in the governing equations and, importantly, to handle moderately stiff and stiff source terms. Stiff source terms arise in the case of abrupt changes of river geometry such as in the case of hydraulic structures like bridges and weirs. Hydraulic interpretation of these conditions with 1D numerical modelling requires particular attention; for instance, a 1st order scheme might either lead to inaccurate solutions or impossibility to simulate these complex conditions. Validation is carried out with several test cases with the aim to check the scheme capability to deal with abrupt geometric changes and to capture the direction and celerity of propagation of bed and water surface disturbances. Validation is done also in a real case by using stage-discharge field measurements in the Ombrone river (Tuscany). The proposed scheme is further employed for the computation of flow rating curves in cross-sections just upstream of an abrupt narrowing, considering both fixed and movable bed conditions and different ratios of contraction for cross-section width. This problem is of particular relevance as, in common engineering practice, rating curves are derived from stage-measuring gauges installed on bridges with flow conditions that are likely to be influenced by local width narrowing. Results show that a higher order scheme is needed in order to deal with stiff source terms and reproduce realistic flow rating curves, unless a strong refinement of the computational grid is performed. This capability appears to be crucial for the computation of rating curves on coarse grids as it allows the modeling of abrupt contractions and jumps in bed bottom elevations, which often occur near cross-sections where stage measuring gauges are installed.

Investigation of Line Width Narrowing and Spectral Jumps of Single Stable Defect Centers in ZnO at Cryogenic Temperature.

Finding new solid state defect centers in novel host materials is crucial for realizing integrated hybrid quantum photonic devices. We present a preparation method for defect centers with photostable bright single photon emission in zinc oxide, a material with promising properties in terms of processability, availability, and applications. A detailed optical study reveals a complex dynamic of intensity fluctuations at room temperature. Measurements at cryogenic temperatures show very sharp (<60 GHz) zero phonon lines (ZPLs) at 580 nm to 620 nm (≈ 2.0 eV) with frozen out fast fluctuations. Remaining discrete jumps of the ZPL, which depend on the excitation power, are observed. The low temperature results will narrow down speculations on the origin of visible-near-infrared (NIR) wavelength defect emission in zinc oxide and provide a basis for improved theoretical models.

Historical geomorphic analysis (1932–2011) of a by-passed river reach in process-based restoration perspectives: The Old Rhine downstream of the Kembs diversion dam (France, Germany)

The Old Rhine downstream of the Kembs diversion dam is one of the largest by-passed river reaches in the world (50km). It offers a unique opportunity to study the morphological effects of by-passing and address physical and ecological restoration approaches in regulated rivers. We conduct a space-time analysis of channel adjustment over a period of 80years (1932 to 2011). We examine planform changes (from aerial photographs), erosional and depositional patterns (from vertical profiles), sediment sizes within the active channel and the new established floodplain, and we date riparian vegetation encroachment. Results show that the Old Rhine exhibited rapid response to the completion of the by-passing scheme in the 1950s, with a 26% narrowing in median active channel width between 1956 and 2008, from vegetation encroachment on dewatered channel margins (mostly groyne fields). The narrowing was accompanied by overbank fine sediment deposition (~1.5cmy−1 aggradation since 1950) as well as slight bed degradation (~0.7cmy−1 since 1950). We found no downstream propagation of active channel narrowing over time, nor propagation of bed degradation. The channel was already significantly adjusted prior to the diversion scheme, following the nineteenth century river straightening and groyne construction. By-passing (dewatering) mainly provided new pioneer habitat for synchronous vegetation establishment and promoted channel stability by decreasing sediment transport owing to peak flow reduction. The morphological budget calculated over the past 20years estimated a downstream output for coarse sediments at 16,000m3y−1, with 80% originating from bed degradation and 20% from bank erosion, without significant inputs from upstream. The present-day morphodynamics remain sensitive to changes because of dynamic bed armouring (<2.1). This retrospective analysis permits us to discuss management strategies for altered rivers. Recommended activities are gravel reintroduction with particle-sizes finer than the armoured river bed to enhance sediment transport and promote form dynamism under current flood magnitudes. This should be coupled with river widening to allow for complex depositional patterns that benefit ecological habitats. These actions should not be implemented without prior analysis of local sediment transfer processes based on in situ experiments and modelling.

Study on fluctuations of flow pathway width in a curved channel with channel width narrowing

Study on fluctuations of flow pathway width in a curved channel with channel width narrowing

Corrosion-Based Failure of Oxide-Aperture VCSELs

Oxide vertical cavity surface emitting lasers (VCSELs) have been known to have a premature failure mode when operated in the presence of atmospheric water vapor, due to corrosion failure. However, information on the precise chain of failure has not previously been available. In this paper, we start by showing the field failure results in a large particle-physics application with 6,000 deployed channels. Next, evidence is shown for the chain of failure between the previously observed oxide aperture tip cracking and delamination, and how that appears to cause dark-line defect networks in the GaAs active region beneath the aperture. In addition, we show how corrosion can be monitored through spectral width narrowing and discuss other symptoms of corrosion-based degradation that show up hundreds or thousands of hours before the rapid failure takes place. Finally, possible ways of preventing corrosion-based failure are discussed.

Effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier

Theoretical and experimental research on the effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier is carried out. The complex Ginzburg—Landau equation is used to simulate the propagation of the pulse in the fiber amplifier and the results show that pulses with negative initial chirp produce the widest supercontinuum and pulses with positive initial chirp produce the narrowest supercontinuum when the central wavelength of the pump lies in the normal dispersion region of the gain fiber. A self-made line width narrowing system is utilized to control the initial chirp of the nanosecond pump pulse and a four-stage master oscillator power amplifier configuration is adopted to produce a high power near-infrared suppercontinuum. The experimental results are in good agreement with simulations which can provide some guidance on further optimization of the system in future work.

Model of the Optical Emission of a Driven Semiconductor Quantum Dot: Phonon-Enhanced Coherent Scattering and Off-Resonant Sideband Narrowing

We study the crucial role played by the solid-state environment in determining the photon emission characteristics of a driven quantum dot. For resonant driving, we predict a phonon enhancement of the coherently emitted radiation field with increasing driving strength, in stark contrast to the conventional expectation of a rapidly decreasing fraction of coherent emission with stronger driving. This surprising behavior results from thermalization of the dot with respect to the phonon bath and leads to a nonstandard regime of resonance fluorescence in which significant coherent scattering and the Mollow triplet coexist. Off resonance, we show that despite the phonon influence, narrowing of dot spectral sideband widths can occur in certain regimes, consistent with an experimental trend.

Control of DNA minor groove width and Fis protein binding by the purine 2-amino group

The width of the DNA minor groove varies with sequence and can be a major determinant of DNA shape recognition by proteins. For example, the minor groove within the center of the Fis–DNA complex narrows to about half the mean minor groove width of canonical B-form DNA to fit onto the protein surface. G/C base pairs within this segment, which is not contacted by the Fis protein, reduce binding affinities up to 2000-fold over A/T-rich sequences. We show here through multiple X-ray structures and binding properties of Fis–DNA complexes containing base analogs that the 2-amino group on guanine is the primary molecular determinant controlling minor groove widths. Molecular dynamics simulations of free-DNA targets with canonical and modified bases further demonstrate that sequence-dependent narrowing of minor groove widths is modulated almost entirely by the presence of purine 2-amino groups. We also provide evidence that protein-mediated phosphate neutralization facilitates minor groove compression and is particularly important for binding to non-optimally shaped DNA duplexes.

Absorption and scattering of scalar wave from Schwarzschild black hole surrounded by magnetic field

The magnetic field is one of the most important constituents of the cosmic space and one of the main sources of the dynamics of interacting matter in the universe. The astronomical observations imply the existence of a strong magnetic fields of up to $10^4-10^8G$ near supermassive black holes in the active galactic nuclei and even around stellar mass black holes. In this paper, with the quantum scattering theory, we analysis the Schr\"{o}edinger-type scalar wave equation of black hole immersed in magnetic field and numerically investigate its absorption cross section and scattering cross section. We find that the absorption cross sections oscillate about the geometric optical value in the high frequency regime. Furthermore in low frequency regime, the magnetic field makes the absorption cross section weaker and this effect is more obviously on lower frequency brand. On the other hand, for the effects of scattering cross sections for the black hole immersed in magnetic field, we find that the magnetic field makes the scattering flux weaker and its width narrower in the forward direction. We find that there also exists the glory phenomenon along the backforward direction. At fixed frequency, the glory peak is higher and the glory width becomes narrower due to the black hole immersed in magnetic field.

Narrowing carpal arch width to increase cross-sectional area of carpal tunnel — a cadaveric study

BackgroundCarpal tunnel morphology plays an essential role in the etiology and treatment of carpal tunnel syndrome. The purpose of this study was to observe the morphological changes of the carpal tunnel as a result of carpal arch width narrowing. It was hypothesized that carpal arch width narrowing would result in increased height and area of the carpal arch. MethodsThe carpal arch width of eight cadaveric hands was narrowed by a custom apparatus and cross-sectional ultrasound images were acquired. The carpal arch height and area were quantified as the carpal arch width was narrowed. Correlation and regression analyses were performed for the carpal arch height and area with respect to the carpal arch width. FindingsThe carpal tunnel became more convex as the carpal arch width was narrowed. The initial carpal arch width, height, and area were 25.7 (SD1.9) mm, 4.1 (SD0.6) mm, and 68.5 (SD14.0) mm2, respectively. The carpal arch height and area negatively correlated with the carpal arch width, with correlation coefficients of −0.974 (SD0.018) and −0.925 (SD0.034), respectively. Linear regression analyses showed a 1mm narrowing of the carpal arch width resulted in proportional increases of 0.40 (SD0.14) mm in the carpal arch height and 4.0 (SD2.2) mm2 in the carpal arch area. InterpretationThis study demonstrates that carpal arch width narrowing leads to increased carpal arch height and area, a potential mechanism to reduce the mechanical insult to the median nerve and relieve symptoms associated with carpal tunnel syndrome.

Fabrication of sub 20-nm wide grooves in a quartz mold by space narrowing dry etching

This paper describes a simple fabrication process of fine groove structures for quartz molds used in UV nanoimprint lithography. Grooves that are finer than the ''spaces'' in line/space resist patterns can be obtained on a quartz substrate with the aid of thin Cr layer and a dry etching process using CHF3. The main cause of the groove width narrowing is deposition of fluorocarbon polymer. By changing etching conditions, a large amount of space narrowing is realized. Grooves with widths of 18nm and 62nm were successfully obtained from 85-nm and 200-nm wide space resist patterns, respectively.

Changes of amplitude integration electroencephalogram (aEEG) in different maturity preterm infant

With the improvement of perinatal care and neonatal intensive care technology in recent years, a preterm infant, especially with small gestational age and very low birth weight, survives more and more. At the same time, adverse neurodevelopmental prognosis caused by brain damage in preterm infant also increased significantly. Preterm infant brain injury has become the most important factor for early death and neurodevelopment of preterm infant. Amplitude integration electroencephalogram (aEEG) has an important clinical value in the assessment of brain development in the maturity of preterm infant. With the application of a neonatal brain function monitor, we value the aEEG graphic continuity, periodicity, narrowband lower margin amplitude, and bandwidth score and analyze wide- and narrowband on the lower bounds of voltage and bandwidth. The graphics of preterm infant aEEG become mature with the growth of the gestational age (1). With the growth of corrected gestational age, the aEEG graphics of preterm infant has the following feature: lower bound voltage of narrowband rising and width narrowing of narrowband (2). Extrauterine life can speed up the maturation of aEEG graphics (3). The aEEG technology is a noninvasive, operable, and simple analysis and suitable for application in the newborn intensive care unit.

Evaluation of Defiberation by Organosolv Ethanolamine Pulping for Integral Utilization of Oil Palm EFB

Organosolv ethanolamine pulping for oil palm empty fruit bunches(EFB) were evaluated in this study. The screen yield by the ethanolamine pulping were higher than that by the soda pulping at the same operation conditions. The higher concentration of ethanolamine solvent resulted in the higher yield and the lower contents of residual lignin. The EFB pulp fibers were the narrower in fiber width but the higher in coarseness than those of the hardwood pulp fiber, while the fiber length of the EFB pulp fiber were similar to that of the hardwood fiber. The intrinsic zero span tensile testing showed the EFB pulp fiber by the 80% ethanolamine pulping were the stronger than the fiber by the soda pulping. The results of this study supported that the ethanolamine pulping could be used as an alternative pulping method for the EFB.