Flattened Profiles Research Articles

Multiscale Modulation of Nanocrystalline Cellulose Hydrogel via Nanocarbon Hybridization for 3D Neuronal Bilayer Formation.

Bacterial biopolymers have drawn much attention owing to their unconventional three-dimensional structures and interesting functions, which are closely integrated with bacterial physiology. The nongenetic modulation of bacterial (Acetobacter xylinum) cellulose synthesis via nanocarbon hybridization, and its application to the emulation of layered neuronal tissue, is reported. The controlled dispersion of graphene oxide (GO) nanoflakes into bacterial cellulose (BC) culture media not only induces structural changes within a crystalline cellulose nanofibril, but also modulates their 3D collective association, leading to substantial reduction in Young's modulus (≈50%) and clear definition of water-hydrogel interfaces. Furthermore, real-time investigation of 3D neuronal networks constructed in this GO-incorporated BC hydrogel with broken chiral nematic ordering revealed the vertical locomotion of growth cones, the accelerated neurite outgrowth (≈100 µm per day) with reduced backward travel length, and the efficient formation of synaptic connectivity with distinct axonal bifurcation abundancy at the ≈750 µm outgrowth from a cell body. In comparison with the pristine BC, GO-BC supports the formation of well-defined neuronal bilayer networks with flattened interfacial profiles and vertical axonal outgrowth, apparently emulating the neuronal development in vivo. We envisioned that our findings may contribute to various applications of engineered BC hydrogel to fundamental neurobiology studies and neural engineering.

Very large suspended graphene as an efficient electron-transparent gate electrode

Although a focused electron beam is required in field emission-based various applications, the electron beam is generally diverged in a conventional triode because the gate has a circular aperture through which the electrons are accelerated to reach the anode. To prevent the beam divergence, a suspended multi-layer graphene (MLG) was fabricated on a very large gate aperture to be used as an electron-transparent gate in a field emission triode. The suspended MLG was observed to have several micro-openings with an average diameter of ∼5 μm formed during a transfer. It was observed that the MLG with micro-openings was likely to act as an efficient transparent gate for electrons even with large number of graphene layers, exhibiting a high transmittance of ∼90%. The solid angles of the beams obtained using conventional gate aperture and suspended MLG gate were 0.225 and 0.074 sr, respectively, indicating that the suspended MLG resulted in a focused electron beam. Simulations confirm that the suspended MLG with micro-openings suppresses the beam divergence in a given triode configuration because the MLG results in the flattened electric field profiles between gate and cathode whereas a distorted potential distribution causing beam divergence occurs around the aperture in a conventional triode.

Generation of broadband single-photon states in photonic-crystal fibers with flattened dispersion profiles

We theoretically analyze the capability of generating broadband single-photon states in photonic crystal fibers (PCF) formed by spontaneous four-wave mixing (SFWM) using femtosecond laser pulses. The design of PCF structures with the flat dispersion profile is proposed. The characteristics of the correlated photon pairs with a broadband spectrum and low spectral correlation for these structures are calculated.

Salivary Cortisol Profiles of Children with Hearing Loss.

It has long been speculated that effortful listening places children with hearing loss at risk for fatigue. School-age children with hearing loss experiencing cumulative stress and listening fatigue on a daily basis might undergo dysregulation of hypothalamic-pituitary-adrenal (HPA) axis activity resulting in elevated or flattened cortisol profiles. The purpose of this study was to examine whether school-age children with hearing loss show different diurnal salivary cortisol patterns than children with normal hearing. Participants included 32 children with mild to moderate hearing loss (14 males; 18 females) and 28 children with normal hearing (19 males; 9 females) ranging in age from 6 to 12 years. Saliva samples were obtained six times per day on two separate school days. Cortisol levels were measured by mass spectrometric detection after liquid-liquid extraction. Salivary cortisol levels between children with hearing loss and children with no hearing loss over the course of the day were examined with hierarchical linear modeling using mixed model statistical analysis. Between-group comparisons were also computed for the area under the curve, an analytical approach for calculating overall cortisol secretion throughout the day. Significant differences in the cortisol awakening response (CAR) were observed between children with hearing loss and children with normal hearing; however, no differences were observed between the two groups subsequent to the cortisol awakening response (60-min postawakening, 10:00 A.M., 2:00 P.M., and 8:00 P.M.). Compared with children with normal hearing, children with hearing loss displayed elevated cortisol levels at awakening and a reduced growth in cortisol secretion from awakening to 30-min postawakening. No significant differences in overall cortisol secretion throughout the day were found between groups (area under the curve). Finally, cortisol levels increased with increasing age for children with hearing loss but not for children with normal hearing. Results of this preliminary study indicate a possible dysregulation in HPA axis activity in children with hearing loss characterized by elevated salivary cortisol levels at awakening and a diminished increase in cortisol from awakening to 30-min postawakening. The pattern of elevated cortisol levels at awakening is consistent with some studies on adults with burnout, a condition characterized by fatigue, loss of energy, and poor coping skills. These findings support the idea that children with hearing loss may experience increased vigilance and need to mobilize energy promptly in preparation for the new day.

THE EMERGENT 1.1-1.7 μm SPECTRUM OF THE EXOPLANET COROT-2B AS MEASURED USING THEHUBBLE SPACE TELESCOPE

We have used Hubble/WFC3 and the G141 grism to measure the secondary eclipse of the transiting very hot Jupiter CoRoT-2b in the 1.1-1.7$\mu$m spectral region. We find an eclipse depth averaged over this band equal to $395^{+69}_{-45}$ parts per million, equivalent to a blackbody temperature of $1788\pm18$K. We study and characterize several WFC3 instrumental effects, especially the "hook" phenomenon described by Deming et al. (2013). We use data from several transiting exoplanet systems to find a quantitative relation between the amplitude of the hook and the exposure level of a given pixel. Although the uncertainties in this relation are too large to allow us to develop an empirical correction for our data, our study provides a useful guide for optimizing exposure levels in future WFC3 observations. We derive the planet's spectrum using a differential method. The planet-to-star contrast increases to longer wavelength within the WFC3 bandpass, but without water absorption or emission to a $3\sigma$ limit of 85 ppm. The slope of the WFC3 spectrum is significantly less than the slope of the best-fit blackbody. We compare all existing eclipse data for this planet to a blackbody spectrum, and to spectra from both solar abundance and carbon-rich (C/O=1) models. A blackbody spectrum is an acceptable fit to the full dataset. Extra continuous opacity due to clouds or haze, and flattened temperature profiles, are strong candidates to produce quasi-blackbody spectra, and to account for the amplitude of the optical eclipses. Our results show ambiguous evidence for a temperature inversion in this planet.

Generation of two-cycle pulses and octave-spanning frequency combs in a dispersion-flattened micro-resonator

We show that octave-spanning Kerr frequency combs with improved spectral flatness of comb lines can be generated in dispersion-flattened microring resonators. The resonator is formed by a strip/slot hybrid waveguide, exhibiting a flat and low anomalous dispersion between two zero-dispersion wavelengths that are separated by one octave from near-infrared to mid-infrared. Such flattened dispersion profiles allow for the generation of mode-locked frequency combs, using relatively low pump power to obtain two-cycle cavity solitons on a chip, associated with the octave-spanning comb bandwidth. The wavelength dependence of the optical loss and of the coupling coefficient and thus wavelength dependent Q-factor are also considered.

SU-E-T-26: Determination of Field Parameters for Unflattened Photon Beams Using a Universal Scaling Factor

Purpose: To investigate unflattened and flattened photon beam profiles and to propose a new method in determining field parameters for unflattened beams. Methods: For flattened beams, field parameters of field size, etc., are defined according to the profile scaled the dose at central axis (D_CAX) to 100%. For unflattened beams, Siemens presents a table of scaling factors (to D_CAX) which are field size and energy dependent. The M. D. Anderson group presented a method to match the dose level at the inflection point for an unflattened beam to that for the corresponding flattened beam. By investigating cross‐plane and in‐plane profiles for the flat beams of Siemens Artiste 6 and 10 MV, Varian 21EX 6 and 10 MV, Trilogy 6 and 18 MV at different field sizes and depths, it was observed that the ratio of the dose at the inflection point (D_IP) to D_CAX remains unchanged within an uncertainty. Therefore, it is proposed to scale any unflattened beam profile by defining its D_IP to this value. After the scaling, the common definitions of field size, penumbra, and asymmetry remain the same. Results: The ratio (D_IP/D_CAX) approaches a Gaussian distribution, yielding a mean of 54% with standard deviation of 2% for all data. The differences between the field sizes determined by this new method and those by Siemens scaling factors are mostly within 1 mm for Artiste 7 UF and 11 UF unflattened beams in a wide range of field sizes and depths. Varying this scaling factor in the 95% confidence interval leads to a variation within ±1 mm for field size determination.Conclusion: This study demonstrates reasonability in use of single “54%” scaling factor to the inflection point for all unflattened beam profiles. The proposed method would provide simplification in determining field parameters for unflattened beams. This work is supported in part by a Siemens research fund.

Supercontinuum generation in non-silica fibers

The development of super continuum sources is driven by the requirements of a wide range of emerging applications. This paper points out how non-silica fibers are of benefit not only because their broad mid-IR transparency enables continuum generation in the 2–5μm region but also since the high intrinsic nonlinearity of the glasses reduces the power-threshold for devices at wavelengths below 2μm. For these glasses, the material zero-dispersion wavelength is typically shifted to long wavelengths compared to silica so dispersion tailoring is key to creating sources based on practical, near-IR, solid state pump lasers. We show how modeling work has produced fiber designs that provide flattened dispersion profiles with high nonlinearity coefficients and zero-dispersion wavelengths in the near-IR. Building on this flexibility, modeling of the pulse dynamics then demonstrates how coherent mid-IR supercontinuum sources could be developed. We also show the importance of the second zero-dispersion wavelength using bismuth fibers as an example. Nonlinear mode-coupling is shown to be a factor in larger core fibers for high-power applications. Demonstrations of supercontinuum in microstructured tellurite fibers, all-solid lead–silicate (SF57) fibers and in bismuth fibers and tapers are then reported to show what has been achieved experimentally using a range of materials and fiber geometries.

A Methodology for Optimization of Power Systems Demand Due to Electric Vehicle Charging Load

This paper presents a methodology of optimizing power systems demand due to electric vehicle (EV) charging load. Following a brief introduction to the charging characteristics of EV batteries, a statistical model is presented for predicting the EV charging load. The optimization problem is then described, and the solution is provided based on the model. An example study is carried out with error and sensitivity analysis to validate the proposed method. Four scenarios of various combinations of EV penetration levels and charging modes are considered in the study. A series of numerical solutions to the optimization problem in these scenarios are obtained by serial quadratic programming. The results show that EV charging load has significant potential to improve the daily load profile of power systems if the charging loads are optimally distributed. It is demonstrated that flattened load profiles may be achieved at all EV penetration levels if the EVs are charged through a fast charging mode. In addition, the implementation of the proposed optimization is discussed with analyses on the impact of travel pattern and the willingness of customers.

Pipe Flow and Wall Turbulence Using a Modified Navier—Stokes Equation

We use a derived incompressible modified Navier—Stokes equation to model pipe flow and wall turbulence. We reproduce the observed flattened paraboloid velocity profiles of turbulence that cannot be obtained directly using standard incompressible Navier—Stokes equation. The solutions found are in harmony with multi-valued velocity fields as a definition of turbulence. Repeating the procedure for the flow of turbulent fluid between two parallel flat plates we find similar flattened velocity profiles. We extend the analysis to the turbulent flow along a single wall and compare the results with experimental data and the established controversial von Karman logarithmic law of the wall.

Multi‐Fluid Modeling of Low‐Recycling Divertor Regimes

AbstractThe low‐recycling regimes of divertor operation in a single‐null NSTX magnetic configuration are studied using computer simulations with the edge plasma transport code UEDGE. The edge plasma transport properties pertinent to the low‐recycling regimes are demonstrated. These include the flux‐limited character of the parallel heat transport and the high plasma temperatures with the flattened profiles in the scrape‐off‐layer. It is shown that to maintain the balance of particle fluxes at the core interface the deuterium gas puffing rate should increase as the divertor recycling coefficient decreases. The radial profiles of the heat load to the outer divertor plate, the upstream radial plasma profiles, and the effects of the cross‐field plasma transport in the low‐recycling regimes are discussed. It is also shown that recycling of lithium impurities evaporating from the divertor plate at high surface temperatures can reverse the low‐recycling divertor operational regime to the high‐recycling one and may cause thermal instability of the divertor plate (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Diurnal cortisol profiles and evening cortisol in post-pubertal adolescents scoring high on the Children's Depression Inventory

Early-onset mood disorders have become a significant public health problem in recent years. The Children's Depression Inventory (CDI) is a commonly used self-report measure. We studied the relation of CDI cut-offs to biological markers of depression such as the diurnal cortisol rhythm and evening cortisol. In 58 post-pubertal adolescents (29 boys and 29 girls, M(age)=15.1 years), the diurnal cortisol profile was derived from three saliva samples, collected at awakening, at noon and in the evening on a week-end day. Longitudinal repeated measurements regression revealed that the group with CDI>18 (high depressive symptoms) clearly had a higher and flatter diurnal rhythm with elevated evening cortisol compared to either the group with CDI between 13 and 18 (moderate depressive symptoms) or CDI<13 (low depressive symptoms). Multinomial logistic regression indicated that evening cortisol was useful in classifying the adolescents in the high depressive symptoms group, while awakening and noon cortisol were not. Our results indicate that the type of high flattened profiles sometimes seen in individuals who are clinically depressed according to diagnostic interviews can also be identified with a self-report inventory, at high levels of symptom reporting. Given the complexity of conducting diagnostic interviews, this result bears clinical relevance.

鉛直円管内気液二相流の乱流構造 : 高速度時系列PTVによる高時空間分解能計測(流体工学,流体機械)

Turbulence modification by dispersed bubbles in an upward pipe flow was investigated by particle tracking velocimetry and bubble shape projection imaging. Time duration of CMOS camera frames was much smaller than the Kolmogorov time scale, so that measurments with a high time resolution were achieved to resolve the dissipation process of turbulence in the presence of bubbles. Two different bubble diameters at the void fraction up to 1.5% were examined. The profiles of mean streamwise velocity of water were flattened in the pipe middle region, because the bubbles accumulating near the pipe wall accelerated the fluid. The flattened mean flow profiles suppressed the shear-induced turbulence intensities. The dissipative eddies around small bubbles, whose size is approximately five times the mean diameter of small bubbles, increased the dissipation rate of turbulence kinetic energy. On the other hand, the turbulence intensities were augmented by the interactions between the eddies generated by the large bubble and the shear-induced turbulence amongst large bubbles, which resulted in the significant enhancement of dissipation process of turbulence kinetic energy.

Neutral modes of a two-dimensional vortex and their link to persistent cat’s eyes

This paper considers the relaxation of a smooth two-dimensional vortex to axisymmetry after the application of an instantaneous, weak external strain field. In this limit the disturbance decays exponentially in time at a rate that is linked to a pole of the associated linear inviscid problem (known as a Landau pole). As a model of a typical vortex distribution that can give rise to cat’s eyes, here distributions are examined that have a basic Gaussian shape but whose profiles have been artificially flattened about some radius rc. A numerical study of the Landau poles for this family of vortices shows that as rc is varied so the decay rate of the disturbance moves smoothly between poles as the decay rates of two Landau poles cross. Cat’s eyes that occur in the nonlinear evolution of a vortex lead to an axisymmetric azimuthally averaged profile with an annulus of approximately uniform vorticity, rather like the artificially flattened profiles investigated. Based on the stability of such profiles it is found that finite thickness cat’s eyes can persist (i.e., the mean profile has a neutral mode) at two distinct radii, and in the limit of a thin flattened region the result that vanishingly thin cat’s eyes only persist at a single radius is recovered. The decay of nonaxisymmetric perturbations to these flattened profiles for larger times is investigated and a comparison made with the result for a Gaussian profile.

Generation of flattened Gaussian beam profiles in a Nd:YAG laser with a Gaussian mirror resonator

We report the experimental generation of a family of flattened Gaussian beams with bell-shaped, flattened, and annular intensity profiles in an electro-optically Q-switched Nd:YAG laser with a variable reflectivity mirror of a Gaussian reflectivity profile as an output coupler. The laser beams of different profiles were generated by modifying the resonator magnification. The propagation characteristics of the experimentally generated flat Gaussian beams were found to be in agreement with theory. To the best of our knowledge this is the first time such a family of flattened Gaussian beams is experimentally generated intracavity using a single variable reflectivity mirror.

Nonmyelinating Schwann Cell Involvement With Well-Preserved Unmyelinated Axons in Charcot-Marie-Tooth Disease Type 1A

Electron microscopic examination was performed to compare morphologic changes of nonmyelinating Schwann cells and unmyelinated axons in patients with Charcot-Marie-Tooth disease type 1A (CMT1A) with peripheral myelin protein 22 duplication (n = 27) and normal control individuals (n = 14). Complete transverse sural nerve cross-sections were obtained in 16 patients and the total number of axons and Schwann cells in each cross-section was estimated. In patients with CMT1A, the number of myelinated axons was significantly decreased, whereas unmyelinated axons were well-preserved and did not show any marked changes. The numbers of nuclei, subunits, and profiles of nonmyelinating Schwann cells were all increased significantly in patients with CMT1A, whereas the numbers of axons per unmyelinated axon-containing subunit were significantly decreased. Schwann cell subunits consisted of layers of flattened cytoplasmic profiles wrapped around unmyelinated axons in the patient with CMT1A. The numbers of nonmyelinating Schwann cell profiles were increased and the numbers of axons per unmyelinated axon-containing subunit were reduced even in young patients with well-preserved myelinated fibers. In conclusion, there is marked alteration of the population and morphology of nonmyelinating Schwann cells, and axon-Schwann cell interactions seem to be regulated differently between myelinated and unmyelinated fibers in CMT1A.

Magnetic relaxation and hyper-resistivity during helicity injection

Transport theory is applied to magnetic helicity injection into plasmas with toroidal geometry. Magnetic relaxation during helicity injection can be described as hyper-resistive diffusion of the current. By using the generalized Balescu–Lenard extension of quasi-linear transport theory, it is shown that hyper-resistive diffusion is generally slow compared with heat transport. It follows that magnetic relaxation due to such turbulence tends to flatten the temperature profile, as observed in reversed-field pinches. Given flattened temperature profiles, Taylor's minimum principle for magnetic relaxation is usefully reformulated as minimum dissipation, yielding circuit equations for electrostatic helicity injection in laboratory devices such as spheromaks and tokamaks. A favorable heat pinch could benefit helicity injection into tokamaks. These results are also relevant to natural phenomena involving the generation of fields by magnetic relaxation.

Laser beam shaping profiles and propagation

We consider four families of functions--the super-Gaussian, flattened Gaussian, Fermi-Dirac, and super-Lorentzian--that have been used to describe flattened irradiance profiles. We determine the shape and width parameters of the different distributions, when each flattened profile has the same radius and slope of the irradiance at its half-height point, and then we evaluate the implicit functional relationship between the shape and width parameters for matched profiles, which provides a quantitative way to compare profiles described by different families of functions. We conclude from an analysis of each profile with matched parameters using Kirchhoff-Fresnel diffraction theory and M2 analysis that the diffraction patterns as they propagate differ by small amounts, which may not be distinguished experimentally. Thus, beam shaping optics is designed to produce either of these four flattened output irradiance distributions with matched parameters will yield similar irradiance distributions as the beam propagates.

Supercontinuum generation at 1.06 μm in holey fibers with dispersion flattened profiles

We report the results of a systematic experimental and theoretical study of 1.06 mum pumped supercontinuum generation in a range of holey fibers with different flattened dispersion profiles. Clear differences in terms of the underpinning mechanisms emerge depending on the spacing between the two fiber zero-dispersion wavelengths. By examining the phase matched wavelength range of the corresponding fiber dispersions, one can predict the maximum achievable supercontinuum bandwidth.

Spatial distribution of far-infrared emission in spiral galaxies. II. Heating sources and gas-to-dust ratio.

We study the radial distribution of the temperature of the warm dust and gas-to-dust mass ratios in a sample of 22 spiral galaxies. The heating capabilities of the diffuse interstellar radiation field (ISRF), based on Desert et al. model, are investigated in 13 of the sample galaxies. In general, the temperature of the warm dust decreases away from the center, reaches a minimum value at the mid-disk and increases again in the outer parts of galaxies. Heating a mixture of small and big grains by the ISRF is able to explain the observed behavior qualitatively. However, ultraviolet photons from recent star formation events are necessary for a detailed matching of the warm dust temperature profiles. Very small grains contribute typically more than 50% to the observed flux at 60 micron beyond half the disk radius in galaxies. Optical depth profiles, derived from the observed 60 micron and warm dust temperature profiles, peak at or close to the galactic center. In 13 of the galaxies, where dust temperature profiles are modeled, we obtain gas-to-dust mass ratio profiles, after correction for the contaminating effects of very small grains. The gas-to-dust mass ratio decreases by a factor of 8 from the center to the optical isophotal radius, where the value approaches the local galactic value. We demonstrate that the observed steep gradient is a result of the over-estimation of the molecular mass, and can be flattened out to within a factor of 2, if the molecular hydrogen mass (H2) is recomputed assuming a metallicity dependent conversion factor from CO intensity to H2 column density. The flattened radial profiles indicate a global gas-to-dust ratio of around 300, which is within a factor of two of the local galactic value.