NASA Astrophysics Data System (ADS)
Li, Jinghe; Song, Linping; Liu, Qing Huo
2016-02-01
A simultaneous multiple frequency contrast source inversion (CSI) method is applied to reconstructing hydrocarbon reservoir targets in a complex multilayered medium in two dimensions. It simulates the effects of a salt dome sedimentary formation in the context of reservoir monitoring. In this method, the stabilized biconjugate-gradient fast Fourier transform (BCGS-FFT) algorithm is applied as a fast solver for the 2D volume integral equation for the forward computation. The inversion technique with CSI combines the efficient FFT algorithm to speed up the matrix-vector multiplication and the stable convergence of the simultaneous multiple frequency CSI in the iteration process. As a result, this method is capable of making quantitative conductivity image reconstruction effectively for large-scale electromagnetic oil exploration problems, including the vertical electromagnetic profiling (VEP) survey investigated here. A number of numerical examples have been demonstrated to validate the effectiveness and capacity of the simultaneous multiple frequency CSI method for a limited array view in VEP.
Hydrates in the California Borderlands: 2D CSEM inversion results from towed and seafloor arrays
NASA Astrophysics Data System (ADS)
Kannberg, P. K.; Constable, S.; Key, K.
2013-12-01
Methane hydrate, an ice-like solid clathrate of methane and water, forms in shallow continental slope sediments, and is both a potential energy source and geologic hazard. Traditionally, methane hydrate presence is inferred from a seismically detected bathymetry tracking velocity inversion, known as the bottom-simulating reflector (BSR). However the BSR is an indicator of free gas at the base of the hydrate stability zone, and not an indicator of hydrate. As such, seismic methods are limited in their capacity to identify and quantify hydrate presence and concentration. Controlled source electromagnetic (CSEM) methods are sensitive to, and are able to directly detect, the presence of electrically resistive methane hydrate and free gas. Additionally, because shallow resistors can mimic deeper resistors in seafloor instruments, understanding the shallow sediment structure can inform deeper crustal modeling. We conducted two CSEM surveys in the San Nicolas Basin, located 150km west of San Diego where a BSR was identified from legacy seismics. Both surveys were conducted using a deep-towed EM transmitter followed by 4 towed 3-axis electric field receivers spaced every 200 m from 400-1000 m behind the transmitter. Either a half-hertz or quarter-hertz modified square wave was transmitted on a 200 ampere, 100 m dipole that was flown between 50 and 100m above the seafloor. The short transmitter-receiver offset allows resolution of shallow structure (less than 1km below seafloor), while the longer transmitter-seafloor receiver resolves deeper structure. Between the two surveys, 27 seafloor receivers were deployed and ~150km of lines were towed, including 5 transects of the basin coincident with legacy seismic lines, and a short-offset repeatability study. Initial 1D modeling showed the presence of a resistor coincident with the BSR. Further 2D inversions using the MARE2DEM inversion program were run for the towed array. These inversions show a 4 ohm-m resistor in the central
A new inversion method for (T2, D) 2D NMR logging and fluid typing
NASA Astrophysics Data System (ADS)
Tan, Maojin; Zou, Youlong; Zhou, Cancan
2013-02-01
One-dimensional nuclear magnetic resonance (1D NMR) logging technology has some significant limitations in fluid typing. However, not only can two-dimensional nuclear magnetic resonance (2D NMR) provide some accurate porosity parameters, but it can also identify fluids more accurately than 1D NMR. In this paper, based on the relaxation mechanism of (T2, D) 2D NMR in a gradient magnetic field, a hybrid inversion method that combines least-squares-based QR decomposition (LSQR) and truncated singular value decomposition (TSVD) is examined in the 2D NMR inversion of various fluid models. The forward modeling and inversion tests are performed in detail with different acquisition parameters, such as magnetic field gradients (G) and echo spacing (TE) groups. The simulated results are discussed and described in detail, the influence of the above-mentioned observation parameters on the inversion accuracy is investigated and analyzed, and the observation parameters in multi-TE activation are optimized. Furthermore, the hybrid inversion can be applied to quantitatively determine the fluid saturation. To study the effects of noise level on the hybrid method and inversion results, the numerical simulation experiments are performed using different signal-to-noise-ratios (SNRs), and the effect of different SNRs on fluid typing using three fluid models are discussed and analyzed in detail.
Efficient 2d full waveform inversion using Fortran coarray
NASA Astrophysics Data System (ADS)
Ryu, Donghyun; Kim, ahreum; Ha, Wansoo
2016-04-01
We developed a time-domain seismic inversion program using the coarray feature of the Fortran 2008 standard to parallelize the algorithm. We converted a 2d acoustic parallel full waveform inversion program with Message Passing Interface (MPI) to a coarray program and examined performance of the two inversion programs. The results show that the speed of the waveform inversion program using the coarray is slightly faster than that of the MPI version. The standard coarray lacks features for collective communication; however, it can be improved in following standards since it is introduced recently. The parallel algorithm can be applied for 3D seismic data processing.
Stochastic Inversion of 2D Magnetotelluric Data
Chen, Jinsong
2010-07-01
The algorithm is developed to invert 2D magnetotelluric (MT) data based on sharp boundary parametrization using a Bayesian framework. Within the algorithm, we consider the locations and the resistivity of regions formed by the interfaces are as unknowns. We use a parallel, adaptive finite-element algorithm to forward simulate frequency-domain MT responses of 2D conductivity structure. Those unknown parameters are spatially correlated and are described by a geostatistical model. The joint posterior probability distribution function is explored by Markov Chain Monte Carlo (MCMC) sampling methods. The developed stochastic model is effective for estimating the interface locations and resistivity. Most importantly, it provides details uncertainty information on each unknown parameter. Hardware requirements: PC, Supercomputer, Multi-platform, Workstation; Software requirements C and Fortan; Operation Systems/version is Linux/Unix or Windows
Stochastic Inversion of 2D Magnetotelluric Data
2010-07-01
The algorithm is developed to invert 2D magnetotelluric (MT) data based on sharp boundary parametrization using a Bayesian framework. Within the algorithm, we consider the locations and the resistivity of regions formed by the interfaces are as unknowns. We use a parallel, adaptive finite-element algorithm to forward simulate frequency-domain MT responses of 2D conductivity structure. Those unknown parameters are spatially correlated and are described by a geostatistical model. The joint posterior probability distribution function ismore » explored by Markov Chain Monte Carlo (MCMC) sampling methods. The developed stochastic model is effective for estimating the interface locations and resistivity. Most importantly, it provides details uncertainty information on each unknown parameter. Hardware requirements: PC, Supercomputer, Multi-platform, Workstation; Software requirements C and Fortan; Operation Systems/version is Linux/Unix or Windows« less
ORMDIN. 2-D Nonlinear Inverse Heat Conduction
Bass, B.R.
1990-05-01
ORMDIN is a finite-element program developed for two-dimensional nonlinear inverse heat conduction analysis as part of the Oak Ridge National Laboratory Pressurized Water Reactor Blowdown Heat Transfer (BDHT) program. One of the primary objectives of the program was to determine the transient surface temperature and surface heat flux of fuel pin simulators from internal thermocouple signals obtained during a loss-of-coolant accident experiment in the Thermal-Hydraulic Test Facility (THTF). ORMDIN was designed primarily to perform a transient two-dimensional nonlinear inverse heat conduction analysis of the THTF bundle 3 heater rod; however, it can be applied to other cylindrical geometries for which the thermophysical properties are prescribed functions of temperature. The program assumes that discretized temperature histories are provided at three thermocouple locations in the interior of the cylinder. Concurrent with the two-dimensional analysis, ORMDIN also generates one-dimensional solutions for each of the three thermocouple radial planes.
Pareto joint inversion of 2D magnetotelluric and gravity data
NASA Astrophysics Data System (ADS)
Miernik, Katarzyna; Bogacz, Adrian; Kozubal, Adam; Danek, Tomasz; Wojdyła, Marek
2015-04-01
In this contribution, the first results of the "Innovative technology of petrophysical parameters estimation of geological media using joint inversion algorithms" project were described. At this stage of the development, Pareto joint inversion scheme for 2D MT and gravity data was used. Additionally, seismic data were provided to set some constrains for the inversion. Sharp Boundary Interface(SBI) approach and description model with set of polygons were used to limit the dimensionality of the solution space. The main engine was based on modified Particle Swarm Optimization(PSO). This algorithm was properly adapted to handle two or more target function at once. Additional algorithm was used to eliminate non- realistic solution proposals. Because PSO is a method of stochastic global optimization, it requires a lot of proposals to be evaluated to find a single Pareto solution and then compose a Pareto front. To optimize this stage parallel computing was used for both inversion engine and 2D MT forward solver. There are many advantages of proposed solution of joint inversion problems. First of all, Pareto scheme eliminates cumbersome rescaling of the target functions, that can highly affect the final solution. Secondly, the whole set of solution is created in one optimization run, providing a choice of the final solution. This choice can be based off qualitative data, that are usually very hard to be incorporated into the regular inversion schema. SBI parameterisation not only limits the problem of dimensionality, but also makes constraining of the solution easier. At this stage of work, decision to test the approach using MT and gravity data was made, because this combination is often used in practice. It is important to mention, that the general solution is not limited to this two methods and it is flexible enough to be used with more than two sources of data. Presented results were obtained for synthetic models, imitating real geological conditions, where
An inverse design method for 2D airfoil
NASA Astrophysics Data System (ADS)
Liang, Zhi-Yong; Cui, Peng; Zhang, Gen-Bao
2010-03-01
The computational method for aerodynamic design of aircraft is applied more universally than before, in which the design of an airfoil is a hot problem. The forward problem is discussed by most relative papers, but inverse method is more useful in practical designs. In this paper, the inverse design of 2D airfoil was investigated. A finite element method based on the variational principle was used for carrying out. Through the simulation, it was shown that the method was fit for the design.
ELRIS2D: A MATLAB Package for the 2D Inversion of DC Resistivity/IP Data
NASA Astrophysics Data System (ADS)
Akca, Irfan
2016-04-01
ELRIS2D is an open source code written in MATLAB for the two-dimensional inversion of direct current resistivity (DCR) and time domain induced polarization (IP) data. The user interface of the program is designed for functionality and ease of use. All available settings of the program can be reached from the main window. The subsurface is discretized using a hybrid mesh generated by the combination of structured and unstructured meshes, which reduces the computational cost of the whole inversion procedure. The inversion routine is based on the smoothness constrained least squares method. In order to verify the program, responses of two test models and field data sets were inverted. The models inverted from the synthetic data sets are consistent with the original test models in both DC resistivity and IP cases. A field data set acquired in an archaeological site is also used for the verification of outcomes of the program in comparison with the excavation results.
Full-waveform inversion in 2D VTI media
NASA Astrophysics Data System (ADS)
Kamath, Nishant
Full-waveform inversion (FWI) is a technique designed to produce a high-resolution model of the subsurface by using information contained in entire seismic waveforms. This thesis presents a methodology for FWI in elastic VTI (transversely isotropic with a vertical axis of symmetry) media and discusses synthetic results for heterogeneous VTI models. First, I develop FWI for multicomponent data from a horizontally layered VTI model. The reflectivity method, which permits computation of only PP reflections or a combination of PP and PSV events, is employed to model the data. The Gauss-Newton technique is used to invert for the interval Thomsen parameters, while keeping the densities fixed at the correct values. Eigenvalue/eigenvector decompostion of the Hessian matrix helps analyze the sensitivity of the objective function to the model parameters. Whereas PP data alone are generally sufficient to constrain all four Thomsen parameters even for conventional spreads, including PS reflections provides better constraints, especially for the deeper part of the model. Next, I derive the gradients of the FWI objective function with respect to the stiffness coefficients of arbitrarily anisotropic media by employing the adjoint-state method. From these expressions, it is straightforward to compute the gradients for parameters of 2D heterogeneous VTI media. FWI is implemented in the time domain with the steepest-descent method used to iteratively update the model. The algorithm is tested on transmitted multicomponent data generated for Gaussian anomalies in Thomsen parameters embedded in homogeneous VTI media. To test the sensitivity of the objective function to different model parameters, I derive an an- alytic expression for the Frechet kernel of FWI for arbitrary anisotropic symmetry by using the Born approximation and asymptotic Green's functions. The amplitude of the kernel, which represents the radiation pattern of a secondary source (that source describes a perturbation
Efficiency of Pareto joint inversion of 2D geophysical data using global optimization methods
NASA Astrophysics Data System (ADS)
Miernik, Katarzyna; Bogacz, Adrian; Kozubal, Adam; Danek, Tomasz; Wojdyła, Marek
2016-04-01
Pareto joint inversion of two or more sets of data is a promising new tool of modern geophysical exploration. In the first stage of our investigation we created software enabling execution of forward solvers of two geophysical methods (2D magnetotelluric and gravity) as well as inversion with possibility of constraining solution with seismic data. In the algorithm solving MT forward solver Helmholtz's equations, finite element method and Dirichlet's boundary conditions were applied. Gravity forward solver was based on Talwani's algorithm. To limit dimensionality of solution space we decided to describe model as sets of polygons, using Sharp Boundary Interface (SBI) approach. The main inversion engine was created using Particle Swarm Optimization (PSO) algorithm adapted to handle two or more target functions and to prevent acceptance of solutions which are non - realistic or incompatible with Pareto scheme. Each inversion run generates single Pareto solution, which can be added to Pareto Front. The PSO inversion engine was parallelized using OpenMP standard, what enabled execution code for practically unlimited amount of threads at once. Thereby computing time of inversion process was significantly decreased. Furthermore, computing efficiency increases with number of PSO iterations. In this contribution we analyze the efficiency of created software solution taking under consideration details of chosen global optimization engine used as a main joint minimization engine. Additionally we study the scale of possible decrease of computational time caused by different methods of parallelization applied for both forward solvers and inversion algorithm. All tests were done for 2D magnetotelluric and gravity data based on real geological media. Obtained results show that even for relatively simple mid end computational infrastructure proposed solution of inversion problem can be applied in practice and used for real life problems of geophysical inversion and interpretation.
2D resistivity inversion using conjugate gradients for a finite element discretization
NASA Astrophysics Data System (ADS)
Bortolozo, C. A.; Santos, F. M.; Porsani, J. L.
2014-12-01
In this work we present a DC 2D inversion algorithm using conjugate gradients relaxation to solve the maximum likelihood inverse equations. We apply, according to Zhang (1995), the maximum likelihood inverse theory developed by Tarantola and Valette (1982) to our 2D resistivity inversion. This algorithm was chosen to this research because it doesn't need to calculate the field's derivatives. Since conjugate gradient techniques only need the results of the sensitivity matrix Ã or its transpose ÃT multiplying a vector, the actual computation of the sensitivity matrix are not performed, according to the methodology described in Zhang (1995). In Zhang (1995), the terms Ãx and ÃTy, are dependent of the stiffness matrix K and its partial derivative ∂K⁄∂ρ. The inversion methodology described in Zhang (1995) is for the case of 3D electrical resistivity by finite differences discretization. So it was necessary to make a series of adjustments to obtain a satisfactory result for 2D electrical inversion using finite element method. The difference between the modeling of 3D resistivity with finite difference and the 2D finite element method are in the integration variable, used in the 2D case. In the 2D case the electrical potential are initially calculated in the transformed domain, including the stiffness matrix, and only in the end is transformed in Cartesian domain. In the case of 3D, described by Zhang (1995) this is done differently, the calculation is done directly in the Cartesian domain. In the literature was not found any work describing how to deal with this problem. Because the calculations of Ãx and ÃTy must be done without having the real stiffness matrix, the adaptation consist in calculate the stiffness matrix and its partial derivative using a set of integration variables. We transform those matrix in the same form has in the potential case, but with different sets of variables. The results will be presented and are very promising.
NASA Astrophysics Data System (ADS)
Randeria, Mohit; Banerjee, Sumilan; Rowland, James
2015-09-01
Most theoretical studies of chiral magnetism, and the resulting spin textures, have focused on 3D systems with broken bulk inversion symmetry, where skyrmions are stabilized by easy-axis anisotropy. In this talk I will describe our results on 2D and quasi-2D systems with broken surface inversion, where we find [1] that skyrmion crystals are much more stable than in 3D, especially for the case of easy-plane anisotropy. These results are of particular interest for thin films, surfaces, and oxide interfaces [2], where broken surface-inversion symmetry and Rashba spin-orbit coupling naturally lead to both the chiral Dzyaloshinskii-Moriya (DM) interaction and to easy-plane compass anisotropy. I will then turn to systems that break both bulk and surface inversion, resulting in two distinct DM terms arising from Dresselhaus and Rashba spin-orbit coupling. I will describe [3] the evolution of the skyrmion structure and of the phase diagram as a function of the ratio of Dresselhaus and Rashba terms, which can be tuned by varying film thickness and strain. [1] S. Banerjee, J. Rowland, O. Erten, and M. Randeria, PRX 4, 031045 (2014). [2] S. Banerjee, O. Erten, and M. Randeria, Nature Phys. 9, 626 (2013). [3] J. Rowland, S. Banerjee and M. Randeria, (unpublished).
Almost but not quite 2D, Non-linear Bayesian Inversion of CSEM Data
NASA Astrophysics Data System (ADS)
Ray, A.; Key, K.; Bodin, T.
2013-12-01
efficiently evaluate the forward response using 1D profiles extracted from the model at the common-midpoints of the EM source-receiver pairs. Since the 1D approximation is locally valid at different midpoint locations, the computation time is far lower than is required by a full 2D or 3D simulation. We have applied this method to both synthetic and real CSEM survey data from the Scarborough gas field on the Northwest shelf of Australia, resulting in a spatially variable quantification of resistivity and its uncertainty in 2D. This Bayesian approach results in a large database of 2D models that comprise a posterior probability distribution, which we can subset to test various hypotheses about the range of model structures compatible with the data. For example, we can subset the model distributions to examine the hypothesis that a resistive reservoir extends overs a certain spatial extent. Depending on how this conditions other parts of the model space, light can be shed on the geological viability of the hypothesis. Since tackling spatially variable uncertainty and trade-offs in 2D and 3D is a challenging research problem, the insights gained from this work may prove valuable for subsequent full 2D and 3D Bayesian inversions.
2-D acoustic VTI full waveform inversion for CCS monitoring
NASA Astrophysics Data System (ADS)
KIM, S.; Kim, W. K.; Min, D. J.; Jeong, W.; OH, J. W.
2014-12-01
These days many geophysicists have been working not only for oil and gas exploration but also for CO2 monitoring for CCS (Carbon Capture and storage). When CO2 is injected and stored to the target layer, it changes the physical properties of subsurface media like p-wave velocity, density and so on. Seismic method is one of the most widely used geophysical methods for CO2 monitoring, because it can delineate physical properties of subsurface media. To prevent CO2 from leaking out of reservoirs, most target areas require caprocks, and shale often acts as a caprock. However, shale has a strong anisotropic property. Without considering the anisotropic property of subsurface media, interpretations of seismic monitoring data can distort the CO2distribution or movement in the subsurface media. For computational efficiency, seismic data interpretation based on acoustic VTI (Vertical Transversely Isotropic) wave equations has been commonly done although it does not consider the shear waves. To investigate the importance of considering anisotropic properties in acoustic FWI (full waveform inversion) for CO2 monitoring, we compare results obtained by the acoustic VTI FWI with those of the conventional acoustic FWI for isotropic case in the frequency domain. Both methods are based on the node-based finite-element method. Numerical examples show that neglecting anisotropic properties of subsurface media can distort distribution of CO2 and degrade reliability of subsurface image obtained by FWI. Acknowledgements This work was supported by the Human Resources Development program (No. 20134010200510) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean government Ministry of Trade, Industry, and Energy and by the "Development of Technology for CO2 Marine Geological Storage" grant funded by the Ministry of Oceans and Fisheries of Korea.
Bootstrap resampling as a tool for uncertainty analysis in 2-D magnetotelluric inversion modelling
NASA Astrophysics Data System (ADS)
Schnaidt, Sebastian; Heinson, Graham
2015-10-01
Uncertainty estimation is a vital part of geophysical numerical modelling. There exist a variety of methods aimed at uncertainty estimation, which are often complicated and difficult to implement. We present an inversion technique that produces multiple solutions, based on bootstrap resampling, to create a qualitative uncertainty measure for 2-D magnetotelluric inversion models. The approach is easy to implement, can be used with almost any inversion code, and does not require access to the inversion software's source code. It is capable of detecting the effect of data uncertainties on the model result rather than just analysing the effect of model variations on the model response. To obtain uncertainty estimates for an inversion model, the original data set is resampled repeatedly and alternate data set realizations are created and inverted. This ensemble of solutions is then statistically analysed to determine the variability between the different solutions. The process yields interpretable uncertainty maps for the inversion model and we demonstrate its effectiveness to qualitatively quantify uncertainty in synthetic model tests and a case study.
Direct design of 2D RF pulses using matrix inversion
NASA Astrophysics Data System (ADS)
Schulte, Rolf F.; Wiesinger, Florian
2013-10-01
Multi-dimensional pulses are frequently used in MRI for applications such as targeted excitation, fat-water separation or metabolic imaging with hyperpolarised 13C compounds. For the design, the problem is typically separated into the different dimensions. In this work, a method to directly design two-dimensional pulses using the small-tip angle approximation is introduced based on a direct matrix representation. The numerical problem is solved in a single step directly in two dimensions by matrix inversion. Exemplary spectral-spatial excitation and spatio-temporal encoding (SPEN) pulses are designed and validated. The main benefits of the direct design approach include a reduction of artefacts in case of spectral-spatial pulses, a simple and straightforward computer implementation and high flexibility in the pulse design.
Estimation of pseudo-2D shear-velocity section by inversion of high frequency surface waves
Luo, Y.; Liu, J.; Xia, J.; Xu, Y.; Liu, Q.
2006-01-01
A scheme to generate pseudo-2D shear-velocity sections with high horizontal resolution and low field cost by inversion of high frequency surface waves is presented. It contains six steps. The key step is the joint method of crossed correlation and phase shift scanning. This joint method chooses only two traces to generate image of dispersion curve. For Rayleigh-wave dispersion is most important for estimation of near-surface shear-wave velocity, it can effectively obtain reliable images of dispersion curves with a couple of traces. The result of a synthetic example shows the feasibility of this scheme. ?? 2005 Society of Exploration Geophysicists.
NASA Astrophysics Data System (ADS)
Ariani, Elsi; Srigutomo, Wahyu
2016-08-01
One-dimensional (1D) and two-dimensional (2D) magnetotelluric data inversion were conducted to reveal the subsurface resistivity structure beneath the eastern part of a volcano in Central Java, Indonesia. Fifteen magnetotelluric sounding data spanning two lines of investigation were inverted using Occam's inversion scheme. The result depict that there are extensively conductive layer (2-10 ohm meter) below the volcanic overburden. This conductive layer is interpreted as the clay cap resulted from thermal alteration. A higher resistivity layer (10-80 ohm meter) underlies the clay cap and is interpreted as the reservoir whose top boundaries vary between 1000 m above and 2000 m below sea level.
Takes Electric or Magnetic field data through Inversion process a 2D Distributon
Newman, Gregory
2008-05-01
Program images 2D distributions in electrical conductivity for geophysical applications. The program can treat surface based and cross well measurement geometries, including inductive and grounded source antennas in the quasi-static limit. The algorithm using Krylov iterative methods to solve for the predicted data and model sensitivities. The model update is achieved using a Gauss-newton optimization process for stability. A new line search capability is now included in the algorithm to insure global convergence of the inversion iteration.
Inversion of 2-D DC resistivity data using rapid optimization and minimal complexity neural network
NASA Astrophysics Data System (ADS)
Singh, U. K.; Tiwari, R. K.; Singh, S. B.
2010-02-01
The backpropagation (BP) artificial neural network (ANN) technique of optimization based on steepest descent algorithm is known to be inept for its poor performance and does not ensure global convergence. Nonlinear and complex DC resistivity data require efficient ANN model and more intensive optimization procedures for better results and interpretations. Improvements in the computational ANN modeling process are described with the goals of enhancing the optimization process and reducing ANN model complexity. Well-established optimization methods, such as Radial basis algorithm (RBA) and Levenberg-Marquardt algorithms (LMA) have frequently been used to deal with complexity and nonlinearity in such complex geophysical records. We examined here the efficiency of trained LMA and RB networks by using 2-D synthetic resistivity data and then finally applied to the actual field vertical electrical resistivity sounding (VES) data collected from the Puga Valley, Jammu and Kashmir, India. The resulting ANN reconstruction resistivity results are compared with the result of existing inversion approaches, which are in good agreement. The depths and resistivity structures obtained by the ANN methods also correlate well with the known drilling results and geologic boundaries. The application of the above ANN algorithms proves to be robust and could be used for fast estimation of resistive structures for other complex earth model also.
Simultaneous elastic parameter inversion in 2-D/3-D TTI medium combined later arrival times
NASA Astrophysics Data System (ADS)
Bai, Chao-ying; Wang, Tao; Yang, Shang-bei; Li, Xing-wang; Huang, Guo-jiao
2016-04-01
Traditional traveltime inversion for anisotropic medium is, in general, based on a "weak" assumption in the anisotropic property, which simplifies both the forward part (ray tracing is performed once only) and the inversion part (a linear inversion solver is possible). But for some real applications, a general (both "weak" and "strong") anisotropic medium should be considered. In such cases, one has to develop a ray tracing algorithm to handle with the general (including "strong") anisotropic medium and also to design a non-linear inversion solver for later tomography. Meanwhile, it is constructive to investigate how much the tomographic resolution can be improved by introducing the later arrivals. For this motivation, we incorporated our newly developed ray tracing algorithm (multistage irregular shortest-path method) for general anisotropic media with a non-linear inversion solver (a damped minimum norm, constrained least squares problem with a conjugate gradient approach) to formulate a non-linear inversion solver for anisotropic medium. This anisotropic traveltime inversion procedure is able to combine the later (reflected) arrival times. Both 2-D/3-D synthetic inversion experiments and comparison tests show that (1) the proposed anisotropic traveltime inversion scheme is able to recover the high contrast anomalies and (2) it is possible to improve the tomographic resolution by introducing the later (reflected) arrivals, but not as expected in the isotropic medium, because the different velocity (qP, qSV and qSH) sensitivities (or derivatives) respective to the different elastic parameters are not the same but are also dependent on the inclination angle.
MARE2DEM: a 2-D inversion code for controlled-source electromagnetic and magnetotelluric data
NASA Astrophysics Data System (ADS)
Key, Kerry
2016-08-01
This work presents MARE2DEM, a freely available code for 2-D anisotropic inversion of magnetotelluric (MT) data and frequency-domain controlled-source electromagnetic (CSEM) data from onshore and offshore surveys. MARE2DEM parameterizes the inverse model using a grid of arbitrarily shaped polygons, where unstructured triangular or quadrilateral grids are typically used due to their ease of construction. Unstructured grids provide significantly more geometric flexibility and parameter efficiency than the structured rectangular grids commonly used by most other inversion codes. Transmitter and receiver components located on topographic slopes can be tilted parallel to the boundary so that the simulated electromagnetic fields accurately reproduce the real survey geometry. The forward solution is implemented with a goal-oriented adaptive finite element method that automatically generates and refines unstructured triangular element grids that conform to the inversion parameter grid, ensuring accurate responses as the model conductivity changes. This dual-grid approach is significantly more efficient than the conventional use of a single grid for both the forward and inverse meshes since the more detailed finite element meshes required for accurate responses do not increase the memory requirements of the inverse problem. Forward solutions are computed in parallel with a highly efficient scaling by partitioning the data into smaller independent modeling tasks consisting of subsets of the input frequencies, transmitters and receivers. Non-linear inversion is carried out with a new Occam inversion approach that requires fewer forward calls. Dense matrix operations are optimized for memory and parallel scalability using the ScaLAPACK parallel library. Free parameters can be bounded using a new non-linear transformation that leaves the transformed parameters nearly the same as the original parameters within the bounds, thereby reducing non-linear smoothing effects. Data
MARE2DEM: a 2-D inversion code for controlled-source electromagnetic and magnetotelluric data
NASA Astrophysics Data System (ADS)
Key, Kerry
2016-10-01
This work presents MARE2DEM, a freely available code for 2-D anisotropic inversion of magnetotelluric (MT) data and frequency-domain controlled-source electromagnetic (CSEM) data from onshore and offshore surveys. MARE2DEM parametrizes the inverse model using a grid of arbitrarily shaped polygons, where unstructured triangular or quadrilateral grids are typically used due to their ease of construction. Unstructured grids provide significantly more geometric flexibility and parameter efficiency than the structured rectangular grids commonly used by most other inversion codes. Transmitter and receiver components located on topographic slopes can be tilted parallel to the boundary so that the simulated electromagnetic fields accurately reproduce the real survey geometry. The forward solution is implemented with a goal-oriented adaptive finite-element method that automatically generates and refines unstructured triangular element grids that conform to the inversion parameter grid, ensuring accurate responses as the model conductivity changes. This dual-grid approach is significantly more efficient than the conventional use of a single grid for both the forward and inverse meshes since the more detailed finite-element meshes required for accurate responses do not increase the memory requirements of the inverse problem. Forward solutions are computed in parallel with a highly efficient scaling by partitioning the data into smaller independent modeling tasks consisting of subsets of the input frequencies, transmitters and receivers. Non-linear inversion is carried out with a new Occam inversion approach that requires fewer forward calls. Dense matrix operations are optimized for memory and parallel scalability using the ScaLAPACK parallel library. Free parameters can be bounded using a new non-linear transformation that leaves the transformed parameters nearly the same as the original parameters within the bounds, thereby reducing non-linear smoothing effects. Data
Observed and simulated power spectra of kinetic and magnetic energy retrieved with 2D inversions
NASA Astrophysics Data System (ADS)
Danilovic, S.; Rempel, M.; van Noort, M.; Cameron, R.
2016-10-01
Context. Information on the origin of internetwork magnetic field is hidden at the smallest spatial scales. Aims: We try to retrieve the power spectra with certainty to the highest spatial frequencies allowed by current instrumentation. Methods: To accomplish this, we use a 2D inversion code that is able to recover information up to the instrumental diffraction limit. Results: The retrieved power spectra have shallow slopes that extend further down to much smaller scales than has been found before. They do not seem to show any power law. The observed slopes at subgranular scales agree with those obtained from recent local dynamo simulations. Small differences are found for the vertical component of kinetic energy that suggest that observations suffer from an instrumental effect that is not taken into account. Conclusions: Local dynamo simulations quantitatively reproduce the observed magnetic energy power spectra on the scales of granulation down to the resolution limit of Hinode/SP, within the error bars inflicted by the method used and the instrumental effects replicated.
NASA Astrophysics Data System (ADS)
Ray, Anandaroop; Key, Kerry; Bodin, Thomas; Myer, David; Constable, Steven
2014-12-01
We apply a reversible-jump Markov chain Monte Carlo method to sample the Bayesian posterior model probability density function of 2-D seafloor resistivity as constrained by marine controlled source electromagnetic data. This density function of earth models conveys information on which parts of the model space are illuminated by the data. Whereas conventional gradient-based inversion approaches require subjective regularization choices to stabilize this highly non-linear and non-unique inverse problem and provide only a single solution with no model uncertainty information, the method we use entirely avoids model regularization. The result of our approach is an ensemble of models that can be visualized and queried to provide meaningful information about the sensitivity of the data to the subsurface, and the level of resolution of model parameters. We represent models in 2-D using a Voronoi cell parametrization. To make the 2-D problem practical, we use a source-receiver common midpoint approximation with 1-D forward modelling. Our algorithm is transdimensional and self-parametrizing where the number of resistivity cells within a 2-D depth section is variable, as are their positions and geometries. Two synthetic studies demonstrate the algorithm's use in the appraisal of a thin, segmented, resistive reservoir which makes for a challenging exploration target. As a demonstration example, we apply our method to survey data collected over the Scarborough gas field on the Northwest Australian shelf.
Efficient 2D and 3D multiparameters frequency-domain full waveform inversion (Invited)
NASA Astrophysics Data System (ADS)
Virieux, J.; Operto, S.; Ribodetti, A.; Ben Hadj Ali, H.; Brossier, R.; Etienne, V.; Gholami, Y.; Hu, G.; Jia, Y.; Pageot, D.; Prieux, V.
2010-12-01
With the tremendous increase of the computational power provided by large-scale distributed-memory platforms and the development of dense 3D multi-component wide-aperture/wide-azimuth surveys, full waveform inversion (FWI) introduced in geophysics by Albert Tarantola has become a re-emerging technique to build high-resolution velocity models of the subsurface. Because of the cost of the forward modeling and the high dimensionality of the model space, full waveform inversion is actually a local optimization problem, the aim of which is the minimization of the misfit between the recorded and modeled seismic wavefields. Among all possible minimization criteria, the L1 norm provides the most robust and easy-to-tune criterion. With such criterion, white noise in all seismograms with outliers does not prevent the convergence to the nearly same minimum as for noise-free data. The frequency formulation of the FWI allows coarse sampling of the frequencies data over few frequencies for the reconstruction of the medium when wide-aperture geometries are considered. A preconditioned quasi-Newton L-BFGS modified algorithm provides scaled gradients of the misfit function for each class of parameters. The gradient is computed by the adjoint-state method where the forward field is stored in the core memory of the computer while computing the backpropagation of residuals for cross-correlation at each point of the medium, thanks to the frequency-domain approach. We are using a sequential multiscale hierarchical inversion algorithm with two nested levels of data preconditioning with respect to frequency and first-arrival time. We are able to reconstruct both Vp and Vs velocity structures in various offshore and onshore environments various configurations of crustal investigation where both body waves (and surface) waves are progressively included in the inversion scheme. Solving the forward problem for 2D geometry could be efficiently performed in frequency by using a direct solver
2-D acoustic Laplace-domain waveform inversion of marine field data
NASA Astrophysics Data System (ADS)
Ha, Wansoo; Chung, Wookeen; Park, Eunjin; Shin, Changsoo
2012-07-01
The Laplace-domain full waveform inversion method can build a macroscale subsurface velocity model that can be used as an accurate initial model for a conventional full waveform inversion. The acoustic Laplace-domain inversion produced is promising for marine field data examples. Although applying an acoustic inversion method to the field data generally requires several pre-processing steps, pre-processing for the Laplace-domain inversion has not been explained in detail. We provide a detailed explanation of how to apply the Laplace-domain waveform inversion to field data through numerical tests with Gulf of Mexico data sets. The pre-processing includes bandpass filtering, muting of the noise before the first arrival, and extraction of the water depth. We choose the range and the interval between the Laplace damping constants empirically by applying a threshold value to the damped time traces and the Laplace-domain wavefields. The observed data are transformed to the Laplace domain using the selected damping; this method yielded a long-wavelength inversion result. The damping constant and the maximum offset affect the penetration depth of the inversion result. The maximum recording time is important for a stable Laplace-transformation and affects the inversion result; however, the latter effect is not significant.
Takes Electric or Magnetic field data through Inversion process a 2D Distributon
2008-05-01
Program images 2D distributions in electrical conductivity for geophysical applications. The program can treat surface based and cross well measurement geometries, including inductive and grounded source antennas in the quasi-static limit. The algorithm using Krylov iterative methods to solve for the predicted data and model sensitivities. The model update is achieved using a Gauss-newton optimization process for stability. A new line search capability is now included in the algorithm to insure global convergence of themore » inversion iteration.« less
2D and 3D separate and joint inversion of airborne ZTEM and ground AMT data: Synthetic model studies
NASA Astrophysics Data System (ADS)
Sasaki, Yutaka; Yi, Myeong-Jong; Choi, Jihyang
2014-05-01
The ZTEM (Z-axis Tipper Electromagnetic) method measures naturally occurring audio-frequency magnetic fields and obtains the tipper function that defines the relationship among the three components of the magnetic field. Since the anomalous tipper responses are caused by the presence of lateral resistivity variations, the ZTEM survey is most suited for detecting and delineating conductive bodies extending to considerable depths, such as graphitic dykes encountered in the exploration of unconformity type uranium deposit. Our simulations shows that inversion of ZTEM data can detect reasonably well multiple conductive dykes placed 1 km apart. One important issue regarding ZTEM inversion is the effect of the initial model, because homogeneous half-space and (1D) layered structures produce no responses. For the 2D model with multiple conductive dykes, the inversion results were useful for locating the dykes even when the initial model was not close to the true background resistivity. For general 3D structures, however, the resolution of the conductive bodies can be reduced considerably depending on the initial model. This is because the tipper magnitudes from 3D conductors are smaller due to boundary charges than the 2D responses. To alleviate this disadvantage of ZTEM surveys, we combined ZTEM and audio-frequency magnetotelluric (AMT) data. Inversion of sparse AMT data was shown to be effective in providing a good initial model for ZTEM inversion. Moreover, simultaneously inverting both data sets led to better results than the sequential approach by enabling to identify structural features that were difficult to resolve from the individual data sets.
2D Laplace-Domain Waveform Inversion of Field Data Using a Power Objective Function
NASA Astrophysics Data System (ADS)
Park, Eunjin; Ha, Wansoo; Chung, Wookeen; Shin, Changsoo; Min, Dong-Joo
2013-12-01
The wavefield in the Laplace domain has a very small amplitude except only near the source point. In order to deal with this characteristic, the logarithmic objective function has been used in many Laplace domain inversion studies. The Laplace-domain waveform inversion using the logarithmic objective function has fewer local minima than the time- or frequency domain inversion. Recently, the power objective function was suggested as an alternative to the logarithmic objective function in the Laplace domain. Since amplitudes of wavefields are very small generally, a power <1 amplifies the wavefields especially at large offset. Therefore, the power objective function can enhance the Laplace-domain inversion results. In previous studies about synthetic datasets, it is confirmed that the inversion using a power objective function shows a similar result when compared with the inversion using a logarithmic objective function. In this paper, we apply an inversion algorithm using a power objective function to field datasets. We perform the waveform inversion using the power objective function and compare the result obtained by the logarithmic objective function. The Gulf of Mexico dataset is used for the comparison. When we use a power objective function in the inversion algorithm, it is important to choose the appropriate exponent. By testing the various exponents, we can select the range of the exponent from 5 × 10-3 to 5 × 10-8 in the Gulf of Mexico dataset. The results obtained from the power objective function with appropriate exponent are very similar to the results of the logarithmic objective function. Even though we do not get better results than the conventional method, we can confirm the possibility of applying the power objective function for field data. In addition, the power objective function shows good results in spite of little difference in the amplitude of the wavefield. Based on these results, we can expect that the power objective function will
1-D and 2-D Probabilistic Inversions of Fault Zone Guided Waves
NASA Astrophysics Data System (ADS)
Gulley, A.; Eccles, J. D.; Kaipio, J. P.; Malin, P. E.
2015-12-01
Fault Zone Guided Waves (FZGWs) are seismic coda that are trapped by the low velocity damage zone of faults. Inversions of these phases can be carried out using their measured dispersion and a Bayesian probability approach. This method utilises a Markov chain Monte Carlo which allows uncertainties and trade-offs to be quantified. Accordingly we have developed a scheme that estimates the dispersion curve and amplitude response variability from a FZGW record. This method allows the computation of both the point estimates and the covariance of the dispersion curve. The subsequent estimation of fault zone parameters is then based on a Gaussian model for the dispersion curve. We then show that inversions using FZGW dispersion data can only resolve fault zone velocity contrast and fault zone width - it leaves densities, absolute country rock velocities and the earthquake location unresolved. We show that they do however significantly affect the estimated fault zone velocities and widths. As these parameters cannot be resolved, we allow for their effects on the estimates of fault zone width and velocity contrast by using the Bayesian approximation error method. We show that using this method reduces computational time from days to minutes and the associated loss of accuracy is insignificant compared to carrying out the inversion on all parameters. We have extended our scheme to 2-D using 1-D slices. The Bayesian approximation error methodology is further employed to provide a 'correction term' with uncertainty for the 1-D slice approximation. We investigate these features with both synthetic data and FZGW data from the Alpine Fault of New Zealand.
Development of a Geocryologic Model of Permafrost From 2D Inversion of IP Profiling
NASA Astrophysics Data System (ADS)
Fortier, R.; Leblanc, A.
2004-05-01
Non-invasive investigation of permafrost along a planned route of pipeline, road or airstrip in cold regions involves the use of effective methods for detecting, characterizing, mapping and monitoring permafrost conditions on various spatial and temporal scales. Among the available near-surface geophysical methods, the electrical resistivity imaging is probably the most suitable method since the resistivity contrast between unfrozen and frozen ground can be one or two orders of magnitude. Induced polarization (IP) profiling was carried out to study the spatial distribution of ground ice in two permafrost mounds near Umiujaq in Nunavik, Canada. A dipole-dipole array was used to perform the IP profiling. Pseudo-sections of electrical resistivity and chargeability giving a misrepresented cross-section of the sub-surface were first draw. The inversion of IP profiling was also performed using DCIP2D developed by UBC-GIF for estimating the spatial distribution of electrical properties in the ground to create realistic models of sub-surface resistivity and chargeability cross-section. The inverse models show clearly the presence of ice-rich core in the permafrost mounds. The ice-rich cores are underlined by high resistivity values while the unfrozen zones show low resistivity values. The localisation of the permafrost table is highlighted by a strong contrast of resistivity while the permafrost base is marked by a transitional change in resistivity. In the hollow between the permafrost mounds, the models show low resistivity values characteristic of unfrozen zone. A synthetic resistivity sounding built from the most acceptable inverse model correlates well with electrical resistivity logging carried out in the permafrost mound during cone penetration tests. The inversion of IP profiling is fundamental for defining realistic models of sub-surface resistivity and chargeability. Electrical resistivity imaging is a appropriate near-surface geophysical method for permafrost
Numerical solution of 2D-vector tomography problem using the method of approximate inverse
NASA Astrophysics Data System (ADS)
Svetov, Ivan; Maltseva, Svetlana; Polyakova, Anna
2016-08-01
We propose a numerical solution of reconstruction problem of a two-dimensional vector field in a unit disk from the known values of the longitudinal and transverse ray transforms. The algorithm is based on the method of approximate inverse. Numerical simulations confirm that the proposed method yields good results of reconstruction of vector fields.
Discrepant Results in a 2-D Marble Collision
ERIC Educational Resources Information Center
Kalajian, Peter
2013-01-01
Video analysis of 2-D collisions is an excellent way to investigate conservation of linear momentum. The often-desired experimental design goal is to minimize the momentum loss in order to demonstrate the conservation law. An air table with colliding pucks is an ideal medium for this experiment, but such equipment is beyond the budget of many…
A 2D inverse problem of predicting boiling heat transfer in a long fin
NASA Astrophysics Data System (ADS)
Orzechowski, Tadeusz
2016-10-01
A method for the determination of local values of the heat transfer coefficient on non-isothermal surfaces was analyzed on the example of a long smooth-surfaced fin made of aluminium. On the basis of the experimental data, two cases were taken into consideration: one-dimensional model for Bi < 0.1 and two-dimensional model for thicker elements. In the case when the drop in temperature over the thickness could be omitted, the rejected local values of heat fluxes were calculated from the integral of the equation describing temperature distribution on the fin. The corresponding boiling curve was plotted on the basis of temperature gradient distribution as a function of superheat. For thicker specimens, where Bi > 0.1, the problem was modelled using a 2-D heat conduction equation, for which the boundary conditions were posed on the surface observed with a thermovision camera. The ill-conditioned inverse problem was solved using a method of heat polynomials, which required validation.
2D multi-parameter elastic seismic imaging by frequency-domain L1-norm full waveform inversion
NASA Astrophysics Data System (ADS)
Brossier, Romain; Operto, Stéphane; Virieux, Jean
2010-05-01
Full waveform inversion (FWI) is becoming a powerful and efficient tool to derive high-resolution quantitative models of the subsurface. In the frequency-domain, computationally efficient FWI algorithms can be designed for wide-aperture acquisition geometries by limiting inversion to few discrete frequencies. However, FWI remains an ill-posed and highly non-linear data-fitting procedure that is sensitive to noise, inaccuracies of the starting model and definition of multiparameter classes. The footprint of the noise in seismic imaging is conventionally mitigated by stacking highly redundant multifold data. However, when the data redundancy is decimated in the framework of efficient frequency-domain FWI, it is essential to assess the sensitivity of the inversion to noise. The impact of the noise in FWI, when applied to decimated data sets, has been marginally illustrated in the past and least-squares minimisation has remained the most popular approach. We investigate in this study the sensitivity of frequency-domain elastic FWI to noise for realistic onshore and offshore synthetic data sets contaminated by ambient random white noise. Four minimisation functionals are assessed in the framework of frequency domain FWI of decimated data: the classical least-square norm (L2), the least-absolute-values norm (L1), and some combinations of both (the Huber and the so-called Hybrid criteria). These functionals are implemented in a massively-parallel, 2D elastic frequency-domain FWI algorithm. A two-level hierarchical algorithm is implemented to mitigate the non-linearity of the inversion in complex environments. The first outer level consists of successive inversions of frequency groups of increasing high-frequency content. This level defines a multi-scale approach while preserving some data redundancy by means of simultaneous inversion of multiple frequencies. The second inner level used complex-valued frequencies for data preconditioning. This preconditioning controls the
Cooperative Cross-Hole Ert and 2-D Full-Waveform Gpr Inversion
NASA Astrophysics Data System (ADS)
Bouchedda, A.; Chouteau, M.
2012-12-01
ERT inversion result is used as FWI conductivity starting model. The conductivity model resulting from FWI is then introduced as reference model in ERT inverse problem using hierarchical Bayesian approach. To validate our methodology and its implementation, two synthetic models were created. Experiments demonstrate that the proposed approach improves the spatial resolution and convergence properties in comparison to classical FWI. This work is an extension to full-waveform inversion of a previously published work (Bouchedda et al., 2012).
Monitoring of injected CO2 using the seismic full waveform inversion for 2-D elastic VTI media
NASA Astrophysics Data System (ADS)
Kim, W. K.; Min, D. J.; KIM, S.; Shin, Y.; Moon, S.
2014-12-01
To monitor the injected CO2 in the subsurface, seismic monitoring techniques are extensively applied because of its high resolution. Among the seismic monitoring techniques, seismic full waveform inversion (FWI) has high applicability because it can delineate parameter changes by injected CO2. When seismic FWIs are applied, subsurface media can be generally assumed to be isotropic. However, most subsurface media are not isotropic, and shale is a representative anisotropic medium, particularly vertical transversely isotropic (VTI) medium, which is often encountered as a barrier to injected CO2. Thus, anisotropic properties of subsurface media are important for monitoring of injected CO2. For these issues, we need to consider anisotropy of subsurface media when seismic FWIs are applied as a monitoring tool for CO2 sequestration. In this study, we performed seismic FWI for 2-D elastic VTI media to investigate the effects of anisotropic properties in CO2 monitoring. For this numerical test, we assumed a geological model, which copies after one of CO2 storage prospects in Korea. We also applied seismic FWI algorithm for 2-D elastic isotropic media for comparison. From this comparison, we noticed that we can obtain more reliable results when we apply the anisotropic FWI algorithm. Numerical examples indicate that we should apply the anisotropic FWI algorithm rather than the isotropic FWI algorithm when we interpret seismic monitoring data acquired in anisotropic media to increase the success of monitoring for injected CO2. Our numerical results can also be used as references for real seismic monitoring of the Korea CO2 sequestration projects in the near future. Acknowledgements This work was supported by the Human Resources Development program (No. 20134010200510) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean government Ministry of Trade, Industry, and Energy and by the "Development of Technology for CO2 Marine
Burgess, Ian B; Aizenberg, Joanna; Lončar, Marko
2013-12-01
Structural hierarchy and complex 3D architecture are characteristics of biological photonic designs that are challenging to reproduce in synthetic materials. Top-down lithography allows for designer patterning of arbitrary shapes, but is largely restricted to planar 2D structures. Self-assembly techniques facilitate easy fabrication of 3D photonic crystals, but controllable defect-integration is difficult. In this paper we combine the advantages of top-down and bottom-up fabrication, developing two techniques to deposit 2D-lithographically-patterned planar layers on top of or in between inverse-opal 3D photonic crystals and creating hierarchical structures that resemble the architecture of the bright green wing scales of the butterfly, Parides sesostris. These fabrication procedures, combining advantages of both top-down and bottom-up fabrication, may prove useful in the development of omnidirectional coloration elements and 3D-2D photonic crystal devices. PMID:24263010
Burgess, Ian B; Aizenberg, Joanna; Lončar, Marko
2013-12-01
Structural hierarchy and complex 3D architecture are characteristics of biological photonic designs that are challenging to reproduce in synthetic materials. Top-down lithography allows for designer patterning of arbitrary shapes, but is largely restricted to planar 2D structures. Self-assembly techniques facilitate easy fabrication of 3D photonic crystals, but controllable defect-integration is difficult. In this paper we combine the advantages of top-down and bottom-up fabrication, developing two techniques to deposit 2D-lithographically-patterned planar layers on top of or in between inverse-opal 3D photonic crystals and creating hierarchical structures that resemble the architecture of the bright green wing scales of the butterfly, Parides sesostris. These fabrication procedures, combining advantages of both top-down and bottom-up fabrication, may prove useful in the development of omnidirectional coloration elements and 3D-2D photonic crystal devices.
2-D magnetotelluric inversion of the central part of Paraná Basin
NASA Astrophysics Data System (ADS)
Santos, E. B.; Santos, H. B.; Vitorello, I.; Pádua, M. B.
2013-12-01
The Paraná Basin is a large sedimentary basin in central-eastern South America that extends through Brazil, Paraguay, Uruguay and Argentina. Evolved completely over the South American continental crust, this Paleozoic basin is filled with sedimentary and volcanic rocks deposited from the Silurian to the Cretaceous, when a significant basaltic effusion covered almost the entire area of the basin. A series of superposed sedimentary and volcanic rock layers were laid down under the influence of different tectonic settings, probably originated from distant collisional dynamics of continental boards that led to the amalgamation of Gondwanaland. The current boundaries of the basin can be the result of issuing erosional or of tectonic origin, such as the building up of large arches and faults. To evaluate the deep structural architecture of the lithosphere under a sedimentary basin is a great challenge, requiring the integration of different geophysical and geological studies. In this paper, we present the resulting Paraná Basin lithospheric model, obtained from processing and inversion of broadband and long-period magnetotelluric soundings along an E-W profile across the central part of the basin, complemented by a qualitative joint interpretation of gravimetric data, in order to obtain a more precise geoelectric model of the deep structure of the region.
A multiple-scale Pascal polynomial for 2D Stokes and inverse Cauchy-Stokes problems
NASA Astrophysics Data System (ADS)
Liu, Chein-Shan; Young, D. L.
2016-05-01
The polynomial expansion method is a useful tool for solving both the direct and inverse Stokes problems, which together with the pointwise collocation technique is easy to derive the algebraic equations for satisfying the Stokes differential equations and the specified boundary conditions. In this paper we propose two novel numerical algorithms, based on a third-first order system and a third-third order system, to solve the direct and the inverse Cauchy problems in Stokes flows by developing a multiple-scale Pascal polynomial method, of which the scales are determined a priori by the collocation points. To assess the performance through numerical experiments, we find that the multiple-scale Pascal polynomial expansion method (MSPEM) is accurate and stable against large noise.
NASA Astrophysics Data System (ADS)
Shulakova, V.
2015-12-01
The quantity of total organic carbon (TOC) and its type determine the ability of source rocks to generate hydrocarbons. Thus, the quantification of TOC content is an essential part of any reservoir characterisation project. Traditionally TOC is estimated from geochemical analysis of core samples. In this case the results are limited spatially by a well location as well as vertically by a number of tested samples. At the same time TOC vertical variability might be very high, changing every 1-3 m. The several methods have been deployed to estimate TOC from well-log data which provides continuous vertical profile estimations. The basin wide information might be provided by the utilization of seismic surveys. The methodology of mapping source rocks based on seismic data has been lately reported to be successful for the thick source rocks (>20 m) with relatively high TOC values up to 3-4% (Løseth et al., 2011). We employ the described approach and demonstrate our findings for a case study from Ceduna Basin (Great Australian Bight, Australia). The reported TOC values estimated from the cores go up to only 1.3%. The organic matter is contained in thin layers of claystones interlayered with sandstones. The workflow included TOC estimation from the well-log data and then seismic data inversion performed in JasonTM software. The inverted acoustic impedance decreases nonlinearly with increasing TOC content. The obtained results comprises 2D section of TOC distribution. The calculated TOC values are in a good agreement with the results of laboratory measurements. The results of this study show that TOC can be successfully estimated from seismic data inversion even in the case of low organic matter values. Further work has to be done to understand whether this approach works for different types of organic matter and stages of its maturation. Løseth H., Wensaas L., Gading M., Duffaut K., Springer M. 2001. Can hydrocarbon source rocks be identified on seismic data? Geology 39/12.
NASA Astrophysics Data System (ADS)
Monnier, J.; Couderc, F.; Dartus, D.; Larnier, K.; Madec, R.; Vila, J.-P.
2016-11-01
The 2D shallow water equations adequately model some geophysical flows with wet-dry fronts (e.g. flood plain or tidal flows); nevertheless deriving accurate, robust and conservative numerical schemes for dynamic wet-dry fronts over complex topographies remains a challenge. Furthermore for these flows, data are generally complex, multi-scale and uncertain. Robust variational inverse algorithms, providing sensitivity maps and data assimilation processes may contribute to breakthrough shallow wet-dry front dynamics modelling. The present study aims at deriving an accurate, positive and stable finite volume scheme in presence of dynamic wet-dry fronts, and some corresponding inverse computational algorithms (variational approach). The schemes and algorithms are assessed on classical and original benchmarks plus a real flood plain test case (Lèze river, France). Original sensitivity maps with respect to the (friction, topography) pair are performed and discussed. The identification of inflow discharges (time series) or friction coefficients (spatially distributed parameters) demonstrate the algorithms efficiency.
Solution of the stationary 2D inverse heat conduction problem by Treffetz method
NASA Astrophysics Data System (ADS)
Cialkowski, Michael J.; Frąckowiak, Andrzej
2002-05-01
The paper presents analysis of a solution of Laplace equation with the use of FEM harmonic basic functions. The essence of the problem is aimed at presenting an approximate solution based on possibly large finite element. Introduction of harmonic functions allows to reduce the order of numerical integration as compared to a classical Finite Element Method. Numerical calculations conform good efficiency of the use of basic harmonic functions for resolving direct and inverse problems of stationary heat conduction. Further part of the paper shows the use of basic harmonic functions for solving Poisson’s equation and for drawing up a complete system of biharmonic and polyharmonic basic functions
NASA Astrophysics Data System (ADS)
Vatankhah, Saeed; Renaut, Rosemary A.; Ardestani, Vahid E.
2014-08-01
The {{\\chi }^{2}} principle generalizes the Morozov discrepancy principle to the augmented residual of the Tikhonov regularized least squares problem. For weighting of the data fidelity by a known Gaussian noise distribution on the measured data, when the stabilizing, or regularization, term is considered to be weighted by unknown inverse covariance information on the model parameters, the minimum of the Tikhonov functional becomes a random variable that follows a {{\\chi }^{2}}-distribution with m+p-n degrees of freedom for the model matrix G of size m\\times n, m\\geqslant n, and regularizer L of size p × n. Then, a Newton root-finding algorithm, employing the generalized singular value decomposition, or singular value decomposition when L = I, can be used to find the regularization parameter α. Here the result and algorithm are extended to the underdetermined case, m, with m+p\\geqslant n. Numerical results first contrast and verify the generalized cross validation, unbiased predictive risk estimation and {{\\chi }^{2}} algorithms when m, with regularizers L approximating zeroth to second order derivative approximations. The inversion of underdetermined 2D focusing gravity data produces models with non-smooth properties, for which typical solvers in the field use an iterative minimum support stabilizer, with both regularizer and regularizing parameter updated each iteration. The {{\\chi }^{2}} and unbiased predictive risk estimator of the regularization parameter are used for the first time in this context. For a simulated underdetermined data set with noise, these regularization parameter estimation methods, as well as the generalized cross validation method, are contrasted with the use of the L-curve and the Morozov discrepancy principle. Experiments demonstrate the efficiency and robustness of the {{\\chi }^{2}} principle and unbiased predictive risk estimator, moreover showing that the L-curve and Morozov discrepancy principle are outperformed in general
A 2D forward and inverse code for streaming potential problems
NASA Astrophysics Data System (ADS)
Soueid Ahmed, A.; Jardani, A.; Revil, A.
2013-12-01
The self-potential method corresponds to the passive measurement of the electrical field in response to the occurrence of natural sources of current in the ground. One of these sources corresponds to the streaming current associated with the flow of the groundwater. We can therefore apply the self- potential method to recover non-intrusively some information regarding the groundwater flow. We first solve the forward problem starting with the solution of the groundwater flow problem, then computing the source current density, and finally solving a Poisson equation for the electrical potential. We use the finite-element method to solve the relevant partial differential equations. In order to reduce the number of (petrophysical) model parameters required to solve the forward problem, we introduced an effective charge density tensor of the pore water, which can be determined directly from the permeability tensor for neutral pore waters. The second aspect of our work concerns the inversion of the self-potential data using Tikhonov regularization with smoothness and weighting depth constraints. This approach accounts for the distribution of the electrical resistivity, which can be independently and approximately determined from electrical resistivity tomography. A numerical code, SP2DINV, has been implemented in Matlab to perform both the forward and inverse modeling. Three synthetic case studies are discussed.
SP2DINV: A 2D forward and inverse code for streaming potential problems
NASA Astrophysics Data System (ADS)
Soueid Ahmed, A.; Jardani, A.; Revil, A.; Dupont, J. P.
2013-09-01
The self-potential method corresponds to the passive measurement of the electrical field in response to the occurrence of natural sources of current in the ground. One of these sources corresponds to the streaming current associated with the flow of the ground water. We can therefore apply the self-potential method to recover non-intrusively some information regarding the ground water flow. We first solve the forward problem starting with the solution of the ground water flow problem, then computing the source current density, and finally solving a Poisson equation for the electrical potential. We use the finite-element method to solve the relevant partial differential equations. In order to reduce the number of (petrophysical) model parameters required to solve the forward problem, we introduced an effective charge density tensor of the pore water, which can be determined directly from the permeability tensor for neutral pore waters. The second aspect of our work concerns the inversion of the self-potential data using Tikhonov regularization with smoothness and weighting depth constraints. This approach accounts for the distribution of the electrical resistivity, which can be independently and approximately determined from electrical resistivity tomography. A numerical code, SP2DINV, has been implemented in Matlab to perform both the forward and inverse modeling. Three synthetic case studies are discussed.
Impact of the Born approximation on the estimation error in 2D inverse scattering
NASA Astrophysics Data System (ADS)
Diong, M. L.; Roueff, A.; Lasaygues, P.; Litman, A.
2016-06-01
The aim is to quantify the impact of the Born approximation on the estimation error for a simple inverse scattering problem, while taking into account the noise measurement features. The proposed method consists of comparing two estimation errors: the error obtained with the Born approximation and the error obtained without it. The first error is characterized by the mean and variance of the maximum likelihood estimator, which are straightforward to compute with the Born approximation because the corresponding estimator is linear. The second error is evaluated with the Cramer–Rao bound (CRB). The CRB is a lower bound on the variance of unbiased estimators and thus does not depend on the choice of the estimation method. Beyond the conclusions that will be established under the Born approximation, this study lays out a general methodology that can be generalized to any other approximation.
HT2DINV: A 2D forward and inverse code for steady-state and transient hydraulic tomography problems
NASA Astrophysics Data System (ADS)
Soueid Ahmed, A.; Jardani, A.; Revil, A.; Dupont, J. P.
2015-12-01
Hydraulic tomography is a technique used to characterize the spatial heterogeneities of storativity and transmissivity fields. The responses of an aquifer to a source of hydraulic stimulations are used to recover the features of the estimated fields using inverse techniques. We developed a 2D free source Matlab package for performing hydraulic tomography analysis in steady state and transient regimes. The package uses the finite elements method to solve the ground water flow equation for simple or complex geometries accounting for the anisotropy of the material properties. The inverse problem is based on implementing the geostatistical quasi-linear approach of Kitanidis combined with the adjoint-state method to compute the required sensitivity matrices. For undetermined inverse problems, the adjoint-state method provides a faster and more accurate approach for the evaluation of sensitivity matrices compared with the finite differences method. Our methodology is organized in a way that permits the end-user to activate parallel computing in order to reduce the computational burden. Three case studies are investigated demonstrating the robustness and efficiency of our approach for inverting hydraulic parameters.
NASA Astrophysics Data System (ADS)
Martin, T. P.; Schultz, A.
2012-12-01
understand the existing baseline subsurface resistivity structure at the Newberry site prior to well stimulation, magnetotelluric (MT) data will be collected in late July 2012 using two long period (1 Hz sampling) Narod Geophysics NIMS MT instruments along with EarthScope MT data aligned in a ~210 km long N-S profile centered on the stimulation zone. A 2-D inverse model will be obtained from the MT data set. The goal of this investigation is to determine the variations in the electrical resistivity in the mid-to-lower crust beneath the western flank of the caldera, providing a deeper view of putative heat sources than existing studies in this
NASA Astrophysics Data System (ADS)
Bignardi, S.; Mantovani, A.; Abu Zeid, N.
2016-08-01
OpenHVSR is a computer program developed in the Matlab environment, designed for the simultaneous modeling and inversion of large Horizontal-to-Vertical Spectral Ratio (HVSR or H/V) datasets in order to construct 2D/3D subsurface models (topography included). The program is designed to provide a high level of interactive experience to the user and still to be of intuitive use. It implements several effective and established tools already present in the code ModelHVSR by Herak (2008), and many novel features such as: -confidence evaluation on lateral heterogeneity -evaluation of frequency dependent single parameter impact on the misfit function -relaxation of Vp/Vs bounds to allow for water table inclusion -a new cost function formulation which include a slope dependent term for fast matching of peaks, which greatly enhances convergence in case of low quality HVSR curves inversion -capability for the user of editing the subsurface model at any time during the inversion and capability to test the changes before acceptance. In what follows, we shall present many features of the program and we shall show its capabilities on both simulated and real data. We aim to supply a powerful tool to the scientific and professional community capable of handling large sets of HSVR curves, to retrieve the most from their microtremor data within a reduced amount of time and allowing the experienced scientist the necessary flexibility to integrate into the model their own geological knowledge of the sites under investigation. This is especially desirable now that microtremor testing has become routinely used. After testing the code over different datasets, both simulated and real, we finally decided to make it available in an open source format. The program is available by contacting the authors.
NASA Astrophysics Data System (ADS)
Gelis, C.; Virieux, J.; Grandjean, G.; Operto, S.
2005-12-01
The superficial weathered zone, few hundreds meters thick, presents highly variable and complex near-surface structures. Energetic seismic surface waves, often called ground roll, may hide information coming from deeper areas. Moreover near-surface anomalies (cavities, overthrusts) are quite important and, therefore, detecting heterogeneities in near-surface areas and quantifying their physical properties is still a challenge for seismic imaging. Since heterogeneities are located in near-surface areas, both surface and body waves induce complex footprints in seismic data. The propagation of 2D P-SV is performed in a frequency domain modeling. This frequency formulation takes into account attenuating behavior and efficiently takes benefit of multisource and multireceiver configurations. A new finite-difference stencil of second order using rotated derivatives axes (Saenger et al., 2000) simulates surface waves precisely and remains stable nearby the free surface and/or rapidly-varying zones. It will be the forward problem kernel of our approach. We follow the matrix formalism of Pratt et al. (1998) and perform a linearized inversion in the least-square sense, since heterogeneities of reasonable amplitudes towards the surrounding medium are considered. We use the gradient method to perform the full waveform inversion for elastic waves. In this formulation we take only the Hessian diagonal part and use a parabolic approximation to find the stepping in the gradient direction. To compute Fréchet derivatives, we resort to the Born and the Rytov approximations and evaluate their performances in transmission and reflection acquisitions geometries. We test as well the influence of the inverted parameters choice. Moreover we highlight the influence of data preconditioning that must be particularly efficient to deal with both body and surface waves. We apply this elastic full waveform inversion to near-surface data, containing strong surface waves and acquired just above a
Modeling Coastal Salinity in Quasi 2D and 3D Using a DUALEM-421 and Inversion Software.
Davies, Gareth; Huang, Jingyi; Monteiro Santos, Fernando Acacio; Triantafilis, John
2015-01-01
Rising sea levels, owing to climate change, are a threat to fresh water coastal aquifers. This is because saline intrusions are caused by increases and intensification of medium-large scale influences including sea level rise, wave climate, tidal cycles, and shifts in beach morphology. Methods are therefore required to understand the dynamics of these interactions. While traditional borehole and galvanic contact resistivity (GCR) techniques have been successful they are time-consuming. Alternatively, frequency-domain electromagnetic (FEM) induction is potentially useful as physical contact with the ground is not required. A DUALEM-421 and EM4Soil inversion software package are used to develop a quasi two- (2D) and quasi three-dimensional (3D) electromagnetic conductivity images (EMCI) across Long Reef Beach located north of Sydney Harbour, New South Wales, Australia. The quasi 2D models discern: the dry sand (<10 mS/m) associated with the incipient dune; sand with fresh water (10 to 20 mS/m); mixing of fresh and saline water (20 to 500 mS/m), and; saline sand of varying moisture (more than 500 mS/m). The quasi 3D EMCIs generated for low and high tides suggest that daily tidal cycles do not have a significant effect on local groundwater salinity. Instead, the saline intrusion is most likely influenced by medium-large scale drivers including local wave climate and morphology along this wave-dominated beach. Further research is required to elucidate the influence of spring-neap tidal cycles, contrasting beach morphological states and sea level rise.
Modeling Coastal Salinity in Quasi 2D and 3D Using a DUALEM-421 and Inversion Software.
Davies, Gareth; Huang, Jingyi; Monteiro Santos, Fernando Acacio; Triantafilis, John
2015-01-01
Rising sea levels, owing to climate change, are a threat to fresh water coastal aquifers. This is because saline intrusions are caused by increases and intensification of medium-large scale influences including sea level rise, wave climate, tidal cycles, and shifts in beach morphology. Methods are therefore required to understand the dynamics of these interactions. While traditional borehole and galvanic contact resistivity (GCR) techniques have been successful they are time-consuming. Alternatively, frequency-domain electromagnetic (FEM) induction is potentially useful as physical contact with the ground is not required. A DUALEM-421 and EM4Soil inversion software package are used to develop a quasi two- (2D) and quasi three-dimensional (3D) electromagnetic conductivity images (EMCI) across Long Reef Beach located north of Sydney Harbour, New South Wales, Australia. The quasi 2D models discern: the dry sand (<10 mS/m) associated with the incipient dune; sand with fresh water (10 to 20 mS/m); mixing of fresh and saline water (20 to 500 mS/m), and; saline sand of varying moisture (more than 500 mS/m). The quasi 3D EMCIs generated for low and high tides suggest that daily tidal cycles do not have a significant effect on local groundwater salinity. Instead, the saline intrusion is most likely influenced by medium-large scale drivers including local wave climate and morphology along this wave-dominated beach. Further research is required to elucidate the influence of spring-neap tidal cycles, contrasting beach morphological states and sea level rise. PMID:25053423
NASA Astrophysics Data System (ADS)
Yang, X.; Zhu, P.; Gu, Y.; Xu, Z.
2015-12-01
Small scale heterogeneities of subsurface medium can be characterized conveniently and effectively using a few simple random medium parameters (RMP), such as autocorrelation length, angle and roughness factor, etc. The estimation of these parameters is significant in both oil reservoir prediction and metallic mine exploration. Poor accuracy and low stability existed in current estimation approaches limit the application of random medium theory in seismic exploration. This study focuses on improving the accuracy and stability of RMP estimation from post-stacked seismic data and its application in the seismic inversion. Experiment and theory analysis indicate that, although the autocorrelation of random medium is related to those of corresponding post-stacked seismic data, the relationship is obviously affected by the seismic dominant frequency, the autocorrelation length, roughness factor and so on. Also the error of calculation of autocorrelation in the case of finite and discrete model decreases the accuracy. In order to improve the precision of estimation of RMP, we design two improved approaches. Firstly, we apply region growing algorithm, which often used in image processing, to reduce the influence of noise in the autocorrelation calculated by the power spectrum method. Secondly, the orientation of autocorrelation is used as a new constraint in the estimation algorithm. The numerical experiments proved that it is feasible. In addition, in post-stack seismic inversion of random medium, the estimated RMP may be used to constrain inverse procedure and to construct the initial model. The experiment results indicate that taking inversed model as random medium and using relatively accurate estimated RMP to construct initial model can get better inversion result, which contained more details conformed to the actual underground medium.
NASA Astrophysics Data System (ADS)
Sass, Paul; Ritter, Oliver; Rybin, Anatolii; Batalev, Vladislav
2013-04-01
Many geodynamic processes governing intra-continental collisional orogeny are largely unexplained and controversial. A key question is the state and dynamic behaviour of the lithosphere at middle and lower crustal levels while continental collision progresses. The Pamir - Tien Shan region in Central Asia may be the best location on Earth to study such lithospheric deformation processes in situ. The mountain ranges and high plateaus formed at the tip of the north-western Indian promontory through the Cenozoic experienced rates of shortening similar to the adjacent Himalaya-Tibet system. Today, the Pamir - Tien Shan orogenic belt hosts some of the deepest active intra-continental subduction zones on Earth and absorbs the highest strain rate over the shortest distance that is manifested in the India-Asia collision zone. The multi-disciplinary Tien Shan - Pamir Geodynamic Program (TIPAGE) was designed to address some of the geodynamic key questions in this region. A magnetotelluric (MT) survey was carried out in concert with other geophysical and geological observations in Kyrgyzstan and Tajikistan, predominantly along a 350 km long and 50 km wide corridor from southern Tajikistan to Osh in Kyrgyzstan across the Pamir Plateau and southern Tien Shan mountain ranges. In total we recorded MT data at 178 stations, 26 of them combine long-period and broad band recordings. We present and compare 2D and 3D MT inversion results. Strike analysis of the data revealed an overall mean geo-electric strike direction consistent with the predominant tectonic trends. 2D inversion yields a reasonable data fit, with exception of some sites which exhibit phases above 90 degrees. 3D inversion was carried out with the ModEM package. We inverted for all four impedance tensor components and the vertical magnetic transfer functions. Topography was also included. The 3D models are generally in agreement with the 2D results but achieve a better data fit, particularly phases which could not be
NASA Astrophysics Data System (ADS)
Sass, P.; Ritter, O.; Rybin, A.; Batalev, V.
2012-12-01
Many geodynamic processes governing intra-continental collisional orogeny are largely unexplained and controversial. A key question is the state and dynamic behaviour of the lithosphere at middle and lower crustal levels while continental collision progresses. The Pamir - Tien Shan region in Central Asia may be the best location on Earth to study such lithospheric deformation processes in situ. The mountain ranges and high plateaus formed at the tip of the north-western Indian promontory through the Cenozoic experienced rates of shortening similar to the adjacent Himalaya-Tibet system. Today, the Pamir - Tien Shan orogenic belt hosts some of the deepest active intra-continental subduction zones on Earth and absorbs the highest strain rate over the shortest distance that is manifested in the India-Asia collision zone. The multi-disciplinary Tien Shan - Pamir Geodynamic Program (TIPAGE) was designed to address some of the geodynamic key questions in this region. A magnetotelluric (MT) survey was carried out in concert with other geophysical and geological observations in Kyrgyzstan and Tajikistan, predominantly along a 350 km long and 50 km wide corridor from southern Tajikistan to Osh in Kyrgyzstan across the Pamir Plateau and southern Tien Shan mountain ranges. In total we recorded MT data at 178 stations, 26 of them combine long-period and broad band recordings. We present and compare 2D and 3D MT inversion results. Strike analysis of the data revealed an overall mean geo-electric strike direction consistent with the predominant tectonic trends. 2D inversion yields a reasonable data fit, with exception of some sites which exhibit phases above 90 degrees. 3D inversion was carried out with the ModEM package. We inverted for all four impedance tensor components and the vertical magnetic transfer functions. Topography was also included. The 3D models are generally in agreement with the 2D results but achieve a better data fit, particularly phases which could not be
Li, Hua; Thériault, Jolaine; Rousselle, Bruno; Subramanian, Balaji; Robichaud, Jacques; Djaoued, Yahia
2014-02-28
A 'dynamic hard-template' infiltration strategy for crack-free large-area synthesis of 2D WO3 inverse opal (IO) films on ITO substrates using a wide range of sizes of sacrificial PS spheres is reported. Thus prepared WO3 IO films were successfully used as an active electrode in the fabrication of an electrochromic device. PMID:24429973
NASA Astrophysics Data System (ADS)
Mashayekhi, Parisa; Ghorbani-Dashtaki, Shoja; Mosaddeghi, Mohammad Reza; Shirani, Hossein; Nodoushan, Ali Reza Mohammadi
2016-04-01
In this study, HYDRUS-2D/3D was used to simulate ponded infiltration through double-ring infiltrometers into a hypothetical loamy soil profile. Twelve scenarios of inverse modelling (divided into three groups) were considered for estimation of Mualem-van Genuchten hydraulic parameters. In the first group, simulation was carried out solely using cumulative infiltration data. In the second group, cumulative infiltration data plus water content at h = -330 cm (field capacity) were used as inputs. In the third group, cumulative infiltration data plus water contents at h = -330 cm (field capacity) and h = -15 000 cm (permanent wilting point) were used simultaneously as predictors. The results showed that numerical inverse modelling of the double-ring infiltrometer data provided a reliable alternative method for determining soil hydraulic parameters. The results also indicated that by reducing the number of hydraulic parameters involved in the optimization process, the simulation error is reduced. The best one in infiltration simulation which parameters α, n, and Ks were optimized using the infiltration data and field capacity as inputs. Including field capacity as additional data was important for better optimization/definition of soil hydraulic functions, but using field capacity and permanent wilting point simultaneously as additional data increased the simulation error.
First results from the Swarm Dedicated Ionospheric Field Inversion chain
NASA Astrophysics Data System (ADS)
Chulliat, A.; Vigneron, P.; Hulot, G.
2016-06-01
Data-based modeling of the magnetic field originating in the Earth's ionosphere is challenging due to the multiple timescales involved and the small spatial scales of some of the current systems, especially the equatorial electrojet (EEJ) that flows along the magnetic dip equator. The Dedicated Ionospheric Field Inversion (DIFI) algorithm inverts a combination of Swarm satellite and ground observatory data at mid- to low latitudes and provides models of the solar-quiet (Sq) and EEJ magnetic fields on the ground and at satellite altitude. The basis functions of these models are spherical harmonics in quasi-dipole coordinates and Fourier series describing the 24-, 12-, 8- and 6-h periodicities, as well as the annual and semiannual variations. A 1-D conductivity model of the Earth and a 2-D conductivity model of the oceans and continents are used to separate the primary ionospheric field from its induced counterpart. First results from the DIFI algorithm confirm several well-known features of the seasonal variability and westward drift speed of the Sq current systems. They also reveal a peculiar seasonal variability of the Sq field in the Southern hemisphere and a longitudinal variability reminiscent of the EEJ wave-4 structure in the same hemisphere. These observations suggest that the Sq and EEJ currents might be electrically coupled, but only for some seasons and longitudes and more so in the Southern hemisphere than in the Northern hemisphere.
Quasi-3D Waveform Inversion for Velocity Structures and Source Process Analyses Using its Results
NASA Astrophysics Data System (ADS)
Hikima, K.; Koketsu, K.
2007-12-01
In this study, we propose an efficient waveform inversion method for 2-D velocity structures and 3-D velocity structures are constructed by interpolating the results of the 2-D inversions. We apply these methods to a source process study of the 2003 Miyagi-ken Hokubu earthquake. We will first construct a velocity model, then determine the source processes of this earthquake sequence using the Green's function calculated with the resultant 3-D velocity model. We formulate the inversion procedure in a 2-D cross section. In a 2-D problem, an earthquake is forced to be a line source. Therefore, we introduce approximate transformation from a line source to a point source (Vidale and Helmberger, 1987). We use the 2-D velocity-stress staggered-grid finite difference scheme, so that the source representation is somewhat different from the original 'source box method' and we apply additional corrections to calculated waveforms. The boundary shapes of layers are expressed by connected nodes and we invert observed waveforms for layer thicknesses at the nodes. We perform 2-D velocity inversions along cross sections which involve a medium-size earthquake and observation points. We assemble the results for many stations and interpolated them to construct the 3-D velocity model. Finally, we calculate waveforms from the target earthquake by the 3-D finite difference method with this velocity model to confirm the validity of the model. We next perform waveform inversions for source processes of the 2003 Miyagi-ken Hokubu earthquake sequence using the resultant 3-D velocity model. We divide the fault plane into northern and southern subplanes, so that the southern subplane includes the hypocenter of the mainshock and the largest foreshock. The strike directions of the northern and southern subplanes were N-S and NE-SW, respectively. The Green's functions for these source inversions are calculated using the reciprocal theorem. We determine the slip models using the 3- D structure and
Electrical 2D Section of a Continental Break-up Region, Gulf of Aden - Results From the ANC Cruise
NASA Astrophysics Data System (ADS)
Toh, H.; Goto, T.; d'Acremont, E.; Leroy, S.
2001-12-01
Seafloor magnetotelluric (MT) array study was conducted in the western part of Sheba Ridge, Gulf of Aden. Five ocean bottom electromagnetometers were deployed along a 200 km long profile perpendicular to a mature ridge segment over the continental break-up region. All these instruments were successfully recovered during the Aden New Century Cruise (ANCC). Temporal EM variations were measured for about three weeks at a sampling rate of 0.1 Hz in order to delineate the electrical structure beneath the continental break-up region. The magnetic and electric resolutions were 10 pT and 60 nV/m, respectively. The time- and tilt-corrected EM time series were processed by the robust remote reference method (Chave et al., 1987) to yield MT impedance tensors at each site for 12 periods ranging from 480s to 40960s. The MT tensors were then rotated toward a direction perpendicular to the mean geological strike of the ridge segment (N27E). The ridge-parallel and ridge-perpendicular components of the tensors were used as TM and TE modes in subsequent two-dimensional (2D) MT inversions (Uchida, 1993) using Akaike's Bayesian Information Criterion (ABIC). A joint 2D ABIC inversion using both modes and incorporating the 2D bathymetry along the profile yielded a model that showed a shallow conductor in the south of the ridge crest centered at a depth of approximately 30 km. The joint model also implies the presence of deeper (>125 km) conductor in the northern side. The bathymetry and the mantle bougurer anomly across the ridge segment are known to show asymmetry (Leroy et al., 2000). Volcanic seamounts seem to be abundant in the south of the ridge crest and the mean depth close to each margin is deeper in the north. The mantle bouguer anomaly extends more in the south-southwest direction as well. These features can be explained by the presence of shallow conductor in the south. It is possible that a hot melt body in the southern conductor supports the relatively intensive volcanic
Arnal, B; Pinton, G; Garapon, P; Pernot, M; Fink, M; Tanter, M
2013-10-01
Shear wave imaging (SWI) maps soft tissue elasticity by measuring shear wave propagation with ultrafast ultrasound acquisitions (10 000 frames s(-1)). This spatiotemporal data can be used as an input for an inverse problem that determines a shear modulus map. Common inversion methods are local: the shear modulus at each point is calculated based on the values of its neighbour (e.g. time-of-flight, wave equation inversion). However, these approaches are sensitive to the information loss such as noise or the lack of the backscattered signal. In this paper, we evaluate the benefits of a global approach for elasticity inversion using a least-squares formulation, which is derived from full waveform inversion in geophysics known as the adjoint method. We simulate an acoustic waveform in a medium with a soft and a hard lesion. For this initial application, full elastic propagation and viscosity are ignored. We demonstrate that the reconstruction of the shear modulus map is robust with a non-uniform background or in the presence of noise with regularization. Compared to regular local inversions, the global approach leads to an increase of contrast (∼+3 dB) and a decrease of the quantification error (∼+2%). We demonstrate that the inversion is reliable in the case when there is no signal measured within the inclusions like hypoechoic lesions which could have an impact on medical diagnosis.
NASA Astrophysics Data System (ADS)
Blacic, Tanya M.; Jun, Hyunggu; Rosado, Hayley; Shin, Changsoo
2016-02-01
In seismic oceanography, processed images highlight small temperature changes, but inversion is needed to obtain absolute temperatures. Local search-based full waveform inversion has a lower computational cost than global search but requires accurate starting models. Unfortunately, most marine seismic data have little associated hydrographic data and the band-limited nature of seismic data makes extracting the long wavelength sound speed trend directly from seismic data inherently challenging. Laplace and Laplace-Fourier domain inversion (LDI) can use rudimentary starting models without prior information about the medium. Data are transformed to the Laplace domain, and a smooth sound speed model is extracted by examining the zero and low frequency components of the damped wavefield. We applied LDI to five synthetic data sets based on oceanographic features and recovered smoothed versions of our synthetic models, showing the viability of LDI for creating starting models suitable for more detailed inversions.
Luo, Y.; Xia, J.; Liu, J.; Xu, Y.; Liu, Q.
2008-01-01
Multichannel Analysis of Surface Waves utilizes a multichannel recording system to estimate near-surface shear (S)-wave velocities from high-frequency Rayleigh waves. A pseudo-2D S-wave velocity (vS) section is constructed by aligning 1D models at the midpoint of each receiver spread and using a spatial interpolation scheme. The horizontal resolution of the section is therefore most influenced by the receiver spread length and the source interval. The receiver spread length sets the theoretical lower limit and any vS structure with its lateral dimension smaller than this length will not be properly resolved in the final vS section. A source interval smaller than the spread length will not improve the horizontal resolution because spatial smearing has already been introduced by the receiver spread. In this paper, we first analyze the horizontal resolution of a pair of synthetic traces. Resolution analysis shows that (1) a pair of traces with a smaller receiver spacing achieves higher horizontal resolution of inverted S-wave velocities but results in a larger relative error; (2) the relative error of the phase velocity at a high frequency is smaller than at a low frequency; and (3) a relative error of the inverted S-wave velocity is affected by the signal-to-noise ratio of data. These results provide us with a guideline to balance the trade-off between receiver spacing (horizontal resolution) and accuracy of the inverted S-wave velocity. We then present a scheme to generate a pseudo-2D S-wave velocity section with high horizontal resolution using multichannel records by inverting high-frequency surface-wave dispersion curves calculated through cross-correlation combined with a phase-shift scanning method. This method chooses only a pair of consecutive traces within a shot gather to calculate a dispersion curve. We finally invert surface-wave dispersion curves of synthetic and real-world data. Inversion results of both synthetic and real-world data demonstrate that
Updated Results for the Wake Vortex Inverse Model
NASA Technical Reports Server (NTRS)
Robins, Robert E.; Lai, David Y.; Delisi, Donald P.; Mellman, George R.
2008-01-01
NorthWest Research Associates (NWRA) has developed an Inverse Model for inverting aircraft wake vortex data. The objective of the inverse modeling is to obtain estimates of the vortex circulation decay and crosswind vertical profiles, using time history measurements of the lateral and vertical position of aircraft vortices. The Inverse Model performs iterative forward model runs using estimates of vortex parameters, vertical crosswind profiles, and vortex circulation as a function of wake age. Iterations are performed until a user-defined criterion is satisfied. Outputs from an Inverse Model run are the best estimates of the time history of the vortex circulation derived from the observed data, the vertical crosswind profile, and several vortex parameters. The forward model, named SHRAPA, used in this inverse modeling is a modified version of the Shear-APA model, and it is described in Section 2 of this document. Details of the Inverse Model are presented in Section 3. The Inverse Model was applied to lidar-observed vortex data at three airports: FAA acquired data from San Francisco International Airport (SFO) and Denver International Airport (DEN), and NASA acquired data from Memphis International Airport (MEM). The results are compared with observed data. This Inverse Model validation is documented in Section 4. A summary is given in Section 5. A user's guide for the inverse wake vortex model is presented in a separate NorthWest Research Associates technical report (Lai and Delisi, 2007a).
Two Eyes, 3D Early Results: Stereoscopic vs 2D Representations of Highly Spatial Scientific Imagery
NASA Astrophysics Data System (ADS)
Price, Aaron
2013-06-01
"Two Eyes, 3D" is a 3-year NSF funded research project to study the educational impacts of using stereoscopic representations in informal settings. The first study conducted as part of the project tested children 5-12 on their ability to perceive spatial elements of slides of scientific objects shown to them in either stereoscopic or 2D format. Children were also tested for prior spatial ability. Early results suggest that stereoscopy does not have a major impact on perceiving spatial elements of an image, but it does have a more significant impact on how the children apply that knowledge when presented with a common sense situation. The project is run by the AAVSO and this study was conducted at the Boston Museum of Science.
Lin, Lin; Yang, Chao; Lu, Jiangfeng; Ying, Lexing; E, Weinan
2009-09-25
We present an efficient parallel algorithm and its implementation for computing the diagonal of $H^-1$ where $H$ is a 2D Kohn-Sham Hamiltonian discretized on a rectangular domain using a standard second order finite difference scheme. This type of calculation can be used to obtain an accurate approximation to the diagonal of a Fermi-Dirac function of $H$ through a recently developed pole-expansion technique \\cite{LinLuYingE2009}. The diagonal elements are needed in electronic structure calculations for quantum mechanical systems \\citeHohenbergKohn1964, KohnSham 1965,DreizlerGross1990. We show how elimination tree is used to organize the parallel computation and how synchronization overhead is reduced by passing data level by level along this tree using the technique of local buffers and relative indices. We analyze the performance of our implementation by examining its load balance and communication overhead. We show that our implementation exhibits an excellent weak scaling on a large-scale high performance distributed parallel machine. When compared with standard approach for evaluating the diagonal a Fermi-Dirac function of a Kohn-Sham Hamiltonian associated a 2D electron quantum dot, the new pole-expansion technique that uses our algorithm to compute the diagonal of $(H-z_i I)^-1$ for a small number of poles $z_i$ is much faster, especially when the quantum dot contains many electrons.
E2GPR - Edit your geometry, Execute GprMax2D and Plot the Results!
NASA Astrophysics Data System (ADS)
Pirrone, Daniele; Pajewski, Lara
2015-04-01
In order to predict correctly the Ground Penetrating Radar (GPR) response from a particular scenario, Maxwell's equations have to be solved, subject to the physical and geometrical properties of the considered problem and to its initial conditions. Several techniques have been developed in computational electromagnetics, for the solution of Maxwell's equations. These methods can be classified into two main categories: differential and integral equation solvers, which can be implemented in the time or spectral domain. All of the different methods present compromises between computational efficiency, stability, and the ability to model complex geometries. The Finite-Difference Time-Domain (FDTD) technique has several advantages over alternative approaches: it has inherent simplicity, efficiency and conditional stability; it is suitable to treat impulsive behavior of the electromagnetic field and can provide either ultra-wideband temporal waveforms or the sinusoidal steady-state response at any frequency within the excitation spectrum; it is accurate and highly versatile; and it has become a mature and well-researched technique. Moreover, the FDTD technique is suitable to be executed on parallel-processing CPU-based computers and to exploit the modern computer visualisation capabilities. GprMax [1] is a very well-known and largely validated FDTD software tool, implemented by A. Giannopoulos and available for free public download on www.gprmax.com, together with examples and a detailled user guide. The tool includes two electromagnetic wave simulators, GprMax2D and GprMax3D, for the full-wave simulation of two-dimensional and three-dimensional GPR models. In GprMax, everything can be done with the aid of simple commands that are used to define the model parameters and results to be calculated. These commands need to be entered in a simple ASCII text file. GprMax output files can be stored in ASCII or binary format. The software is provided with MATLAB functions, which
E2GPR - Edit your geometry, Execute GprMax2D and Plot the Results!
NASA Astrophysics Data System (ADS)
Pirrone, Daniele; Pajewski, Lara
2015-04-01
In order to predict correctly the Ground Penetrating Radar (GPR) response from a particular scenario, Maxwell's equations have to be solved, subject to the physical and geometrical properties of the considered problem and to its initial conditions. Several techniques have been developed in computational electromagnetics, for the solution of Maxwell's equations. These methods can be classified into two main categories: differential and integral equation solvers, which can be implemented in the time or spectral domain. All of the different methods present compromises between computational efficiency, stability, and the ability to model complex geometries. The Finite-Difference Time-Domain (FDTD) technique has several advantages over alternative approaches: it has inherent simplicity, efficiency and conditional stability; it is suitable to treat impulsive behavior of the electromagnetic field and can provide either ultra-wideband temporal waveforms or the sinusoidal steady-state response at any frequency within the excitation spectrum; it is accurate and highly versatile; and it has become a mature and well-researched technique. Moreover, the FDTD technique is suitable to be executed on parallel-processing CPU-based computers and to exploit the modern computer visualisation capabilities. GprMax [1] is a very well-known and largely validated FDTD software tool, implemented by A. Giannopoulos and available for free public download on www.gprmax.com, together with examples and a detailled user guide. The tool includes two electromagnetic wave simulators, GprMax2D and GprMax3D, for the full-wave simulation of two-dimensional and three-dimensional GPR models. In GprMax, everything can be done with the aid of simple commands that are used to define the model parameters and results to be calculated. These commands need to be entered in a simple ASCII text file. GprMax output files can be stored in ASCII or binary format. The software is provided with MATLAB functions, which
National Prociency Testing Result of CYP2D6*10 Genotyping for Adjuvant Tamoxifen Therapy in China.
Lin, Guigao; Zhang, Kuo; Yi, Lang; Han, Yanxi; Xie, Jiehong; Li, Jinming
2016-01-01
Tamoxifen has been successfully used for treating breast cancer and preventing cancer recurrence. Cytochrome P450 2D6 (CYP2D6) plays a key role in the process of metabolizing tamoxifen to its active moiety, endoxifen. Patients with variants of the CYP2D6 gene may not receive the full benefit of tamoxifen treatment. The CYP2D6*10 variant (the most common variant in Asians) was analyzed to optimize the prescription of tamoxifen in China. To ensure referring clinicians have accurate information for genotype-guided tamoxifen treatment, the Chinese National Center for Clinical Laboratories (NCCL) organized a national proficiency testing (PT) to evaluate the performance of laboratories providing CYP2D6*10 genotyping. Ten genomic DNA samples with CYP2D6 wild-type or CYP2D6*10 variants were validated by PCR-sequencing and sent to 28 participant laboratories. The genotyping results and pharmacogenomic test reports were submitted and evaluated by NCCL experts. Additional information regarding the number of samples tested, the accreditation/certification status, and detecting technology was also requested. Thirty-one data sets were received, with a corresponding analytical sensitivity of 98.2% (548/558 challenges; 95% confidence interval: 96.7-99.1%) and an analytic specificity of 96.5% (675/682; 95% confidence interval: 97.9-99.5%). Overall, 25/28 participants correctly identified CYP2D6*10 status in 10 samples; however, two laboratories made serious genotyping errors. Most of the essential information was included in the 20 submitted CYP2D6*10 test reports. The majority of Chinese laboratories are reliable for detecting the CYP2D6*10 variant; however, several issues revealed in this study underline the importance of PT schemes in continued external assessment and provision of guidelines. PMID:27603206
National Prociency Testing Result of CYP2D6*10 Genotyping for Adjuvant Tamoxifen Therapy in China.
Lin, Guigao; Zhang, Kuo; Yi, Lang; Han, Yanxi; Xie, Jiehong; Li, Jinming
2016-01-01
Tamoxifen has been successfully used for treating breast cancer and preventing cancer recurrence. Cytochrome P450 2D6 (CYP2D6) plays a key role in the process of metabolizing tamoxifen to its active moiety, endoxifen. Patients with variants of the CYP2D6 gene may not receive the full benefit of tamoxifen treatment. The CYP2D6*10 variant (the most common variant in Asians) was analyzed to optimize the prescription of tamoxifen in China. To ensure referring clinicians have accurate information for genotype-guided tamoxifen treatment, the Chinese National Center for Clinical Laboratories (NCCL) organized a national proficiency testing (PT) to evaluate the performance of laboratories providing CYP2D6*10 genotyping. Ten genomic DNA samples with CYP2D6 wild-type or CYP2D6*10 variants were validated by PCR-sequencing and sent to 28 participant laboratories. The genotyping results and pharmacogenomic test reports were submitted and evaluated by NCCL experts. Additional information regarding the number of samples tested, the accreditation/certification status, and detecting technology was also requested. Thirty-one data sets were received, with a corresponding analytical sensitivity of 98.2% (548/558 challenges; 95% confidence interval: 96.7-99.1%) and an analytic specificity of 96.5% (675/682; 95% confidence interval: 97.9-99.5%). Overall, 25/28 participants correctly identified CYP2D6*10 status in 10 samples; however, two laboratories made serious genotyping errors. Most of the essential information was included in the 20 submitted CYP2D6*10 test reports. The majority of Chinese laboratories are reliable for detecting the CYP2D6*10 variant; however, several issues revealed in this study underline the importance of PT schemes in continued external assessment and provision of guidelines.
National Prociency Testing Result of CYP2D6*10 Genotyping for Adjuvant Tamoxifen Therapy in China
Lin, Guigao; Zhang, Kuo; Yi, Lang; Han, Yanxi; Xie, Jiehong; Li, Jinming
2016-01-01
Tamoxifen has been successfully used for treating breast cancer and preventing cancer recurrence. Cytochrome P450 2D6 (CYP2D6) plays a key role in the process of metabolizing tamoxifen to its active moiety, endoxifen. Patients with variants of the CYP2D6 gene may not receive the full benefit of tamoxifen treatment. The CYP2D6*10 variant (the most common variant in Asians) was analyzed to optimize the prescription of tamoxifen in China. To ensure referring clinicians have accurate information for genotype-guided tamoxifen treatment, the Chinese National Center for Clinical Laboratories (NCCL) organized a national proficiency testing (PT) to evaluate the performance of laboratories providing CYP2D6*10 genotyping. Ten genomic DNA samples with CYP2D6 wild-type or CYP2D6*10 variants were validated by PCR-sequencing and sent to 28 participant laboratories. The genotyping results and pharmacogenomic test reports were submitted and evaluated by NCCL experts. Additional information regarding the number of samples tested, the accreditation/certification status, and detecting technology was also requested. Thirty-one data sets were received, with a corresponding analytical sensitivity of 98.2% (548/558 challenges; 95% confidence interval: 96.7–99.1%) and an analytic specificity of 96.5% (675/682; 95% confidence interval: 97.9–99.5%). Overall, 25/28 participants correctly identified CYP2D6*10 status in 10 samples; however, two laboratories made serious genotyping errors. Most of the essential information was included in the 20 submitted CYP2D6*10 test reports. The majority of Chinese laboratories are reliable for detecting the CYP2D6*10 variant; however, several issues revealed in this study underline the importance of PT schemes in continued external assessment and provision of guidelines. PMID:27603206
A novel KMT2D mutation resulting in Kabuki syndrome: A case report
Lu, Jun; Mo, Guiling; Ling, Yaojun; Ji, Lijuan
2016-01-01
Kabuki syndrome (KS) is a rare genetic syndrome characterized by multiple congenital anomalies and varying degrees of mental retardation. Patients with KS often present with facial, skeletal, visceral and dermatoglyphic abnormalities, cardiac anomalies and immunological defects. Mutation of the lysine methyltransferase 2D (KMT2D) gene (formerly known as MLL2) is the primary cause of KS. The present study reported the case of a 4-year-old Chinese girl who presented with atypical KS, including atypical facial features, unclear speech and suspected mental retardation. A diagnosis of KS was confirmed by genetic testing, which revealed a nonsense mutation in exon 16 of KMT2D (c.4485C>A, Tyr1495Ter). To the best of our knowledge, this is a novel mutation that has not been reported previously. The present case underscores the importance of genetic testing in KS diagnosis. PMID:27573763
A novel KMT2D mutation resulting in Kabuki syndrome: A case report.
Lu, Jun; Mo, Guiling; Ling, Yaojun; Ji, Lijuan
2016-10-01
Kabuki syndrome (KS) is a rare genetic syndrome characterized by multiple congenital anomalies and varying degrees of mental retardation. Patients with KS often present with facial, skeletal, visceral and dermatoglyphic abnormalities, cardiac anomalies and immunological defects. Mutation of the lysine methyltransferase 2D (KMT2D) gene (formerly known as MLL2) is the primary cause of KS. The present study reported the case of a 4‑year‑old Chinese girl who presented with atypical KS, including atypical facial features, unclear speech and suspected mental retardation. A diagnosis of KS was confirmed by genetic testing, which revealed a nonsense mutation in exon 16 of KMT2D (c.4485C>A, Tyr1495Ter). To the best of our knowledge, this is a novel mutation that has not been reported previously. The present case underscores the importance of genetic testing in KS diagnosis. PMID:27573763
NASA Astrophysics Data System (ADS)
Abdelmalak, M.; Mourgues, R.; Bureau, D.
2012-04-01
The analysis of surface deformation in response to approaching intrusion is important for assessing volcanic hazards. In this paper, we present results from 2D scaled models of magma intrusion, in which we discuss the propagation mode and related surface deformation during dyke growth. Our experiments consist in the injection of analogue magma (Golden syrup) into cohesive fine-grained silica powder, simulating the brittle upper crust. Using an optical image correlation technique (Particle Imaging Velocimetry), we were able to follow the surface deformation, the displacements within the country rock and to calculate strains induced by the magma emplacement. We identified two kinds of intrusion morphologies resulting from different interactions between the dyke and plastic deformations occurring in the country rock near the surface. In both morphologies, the dyke is vertical at depth. Our analysis demonstrates that both hydraulic tensile opening and shear-related propagation operate during this first stage of vertical growth. At the same time, the surface lifted up and formed a smooth symmetrical dome. Both types of morphologies differ in the upper part. During a second stage of evolution, the first type of intrusion inclined at a dip between 45 to 65°. This inclination is not caused by shear deformations and is attributed to stress rotation near the tip. Closer to the surface, the growth of the inclined sheet creates shear bands which conduct the fluid toward the surface. The surface uplift becomes asymmetric. The second type of intrusion does not rotate at depth and continues its vertical propagation by catching vertical tensile cracks. The intrusion of magma in these cracks creates horizontal stresses which are responsible for the closure of fractures and the formation of reverse faults. At the surface the dome remains symmetrical. For both intrusions, the surface uplift accelerates during the second stage and it is strongly influenced by the presence or the
Appraisal of geodynamic inversion results: a data mining approach
NASA Astrophysics Data System (ADS)
Baumann, T. S.
2016-11-01
Bayesian sampling based inversions require many thousands or even millions of forward models, depending on how nonlinear or non-unique the inverse problem is, and how many unknowns are involved. The result of such a probabilistic inversion is not a single `best-fit' model, but rather a probability distribution that is represented by the entire model ensemble. Often, a geophysical inverse problem is non-unique, and the corresponding posterior distribution is multimodal, meaning that the distribution consists of clusters with similar models that represent the observations equally well. In these cases, we would like to visualize the characteristic model properties within each of these clusters of models. However, even for a moderate number of inversion parameters, a manual appraisal for a large number of models is not feasible. This poses the question whether it is possible to extract end-member models that represent each of the best-fit regions including their uncertainties. Here, I show how a machine learning tool can be used to characterize end-member models, including their uncertainties, from a complete model ensemble that represents a posterior probability distribution. The model ensemble used here results from a nonlinear geodynamic inverse problem, where rheological properties of the lithosphere are constrained from multiple geophysical observations. It is demonstrated that by taking vertical cross-sections through the effective viscosity structure of each of the models, the entire model ensemble can be classified into four end-member model categories that have a similar effective viscosity structure. These classification results are helpful to explore the non-uniqueness of the inverse problem and can be used to compute representative data fits for each of the end-member models. Conversely, these insights also reveal how new observational constraints could reduce the non-uniqueness. The method is not limited to geodynamic applications and a generalized MATLAB
Appraisal of geodynamic inversion results: A data mining approach
NASA Astrophysics Data System (ADS)
Baumann, T. S.
2016-07-01
Bayesian sampling based inversions require many thousands or even millions of forward models, depending on how non-linear or non-unique the inverse problem is, and how many unknowns are involved. The result of such a probabilistic inversion is not a single `best-fit' model, but rather a probability distribution that is represented by the entire model ensemble. Often, a geophysical inverse problem is non-unique, and the corresponding posterior distribution is multimodal, meaning that the distribution consists of clusters with similar models that represent the observations equally well. In these cases, we would like to visualise the characteristic model properties within each of these clusters of models. However, even for a moderate number of inversion parameters, a manual appraisal for a large number of models is not feasible. This poses the question whether it is possible to extract end-member models that represent each of the best fit regions including their uncertainties. Here, I show how a machine learning tool can be used to characterise end-member models, including their uncertainties, from a complete model ensemble that represents a posterior probability distribution. The model ensemble used here, results from a non-linear geodynamic inverse problem, where rheological properties of the lithosphere are constrained from multiple geophysical observations. It is demonstrated that by taking vertical cross-sections through the effective viscosity structure of each of the models, the entire model ensemble can be classified into 4 end-member model categories that have a similar effective viscosity structure. These classification results are helpful to explore the non-uniqueness of the inverse problem and can be used to compute representative data fits for each of the end member models. Conversely, these insights also reveal how new observational constraints could reduce the non-uniqueness. The method is not limited to geodynamic applications and a generalised MATLAB
Recombinant chromosome 18 resulting from a maternal pericentric inversion
Ayukawa, Hiroshi; Tsukahara, Masato; Fukuda, Masamichi; Kondoh, Osamu
1994-05-01
We report on a newborn girl with duplication of 18q12.2{yields}18 qter and deficiency of 18p11.2{yields}18pter which resulted from meiotic recombination of the maternal pericentric inversion, inv(18)(p11.2q12.2). Her clinical manifestations were compatible with those of partial trisomy 18q syndrome. We review the previously reported 9 cases in 8 families of rec(18) resulting from recombination of a parental pericentric inversion. 8 refs., 3 figs., 1 tab.
NASA Astrophysics Data System (ADS)
Dagnino, D.; Sallarès, V.; Biescas, B.; Ranero, C. R.
2016-08-01
This work demonstrates the feasibility of 2-D time-domain, adjoint-state acoustic full-waveform inversion (FWI) to retrieve high-resolution models of ocean physical parameters such as sound speed, temperature and salinity. The proposed method is first described and then applied to prestack multichannel seismic (MCS) data acquired in the Gulf of Cadiz (SW Iberia) in 2007 in the framework of the Geophysical Oceanography project. The inversion strategy flow includes specifically designed data preconditioning for acoustic noise reduction, followed by the inversion of sound speed in the shotgather domain. We show that the final sound speed model has a horizontal resolution of ˜ 70 m, which is two orders of magnitude better than that of the initial model constructed with coincident eXpendable Bathy Thermograph (XBT) data, and close to the theoretical resolution of O(λ). Temperature (T) and salinity (S) are retrieved with the same lateral resolution as sound speed by combining the inverted sound speed model with the thermodynamic equation of seawater and a local, depth-dependent T-S relation derived from regional conductivity-temperature-depth (CTD) measurements of the National Oceanic and Atmospheric Administration (NOAA) database. The comparison of the inverted T and S models with XBT and CTD casts deployed simultaneously to the MCS acquisition shows that the thermohaline contrasts are resolved with an accuracy of 0.18oC for temperature and 0.08 PSU for salinity. The combination of oceanographic and MCS data into a common, pseudo-automatic inversion scheme allows to quantitatively resolve submeso-scale features that ought to be incorporated into larger-scale ocean models of oceans structure and circulation.
Cooper, Mitchell A; Nguyen, Thanh D; Spincemaille, Pascal; Prince, Martin R; Weinsaft, Jonathan W; Wang, Yi
2012-11-01
Fast methods using balanced steady-state free precession have been developed to reduce the scan time of T₁ and T₂ mapping. However, flip angle (FA) profiles created by the short radiofrequency pulses used in steady-state free precession deviate substantially from the ideal rectangular profile, causing T₁ and T₂ mapping errors. The purpose of this study was to develop a FA profile correction for T₁ and T₂ mapping with Look-Locker 2D inversion recovery steady-state free precession and to validate this method using 2D spin echo as a reference standard. Phantom studies showed consistent improvement in T₁ and T₂ accuracy using profile correction at multiple FAs. Over six human calves, profile correction provided muscle T₁ estimates with mean error ranging from excellent (-0.6%) at repetition time/FA = 18 ms/60° to acceptable (6.8%) at repetition time/FA = 4.9 ms/30°, while muscle T₂ estimates were less accurate with mean errors of 31.2% and 47.9%, respectively.
NASA Astrophysics Data System (ADS)
Salewski, M.; Geiger, B.; Jacobsen, A. S.; García-Muñoz, M.; Heidbrink, W. W.; Korsholm, S. B.; Leipold, F.; Madsen, J.; Moseev, D.; Nielsen, S. K.; Rasmussen, J.; Stejner, M.; Tardini, G.; Weiland, M.; the ASDEX Upgrade Team
2014-02-01
We present the first measurement of a local fast-ion 2D velocity distribution function f(v‖, v⊥). To this end, we heated a plasma in ASDEX Upgrade by neutral beam injection and measured spectra of fast-ion Dα (FIDA) light from the plasma centre in three views simultaneously. The measured spectra agree very well with synthetic spectra calculated from a TRANSP/NUBEAM simulation. Based on the measured FIDA spectra alone, we infer f(v‖, v⊥) by tomographic inversion. Salient features of our measurement of f(v‖, v⊥) agree reasonably well with the simulation: the measured as well as the simulated f(v‖, v⊥) are lopsided towards negative velocities parallel to the magnetic field, and they have similar shapes. Further, the peaks in the simulation of f(v‖, v⊥) at full and half injection energies of the neutral beam also appear in the measurement at similar velocity-space locations. We expect that we can measure spectra in up to seven views simultaneously in the next ASDEX Upgrade campaign which would further improve measurements of f(v‖, v⊥) by tomographic inversion.
NASA Astrophysics Data System (ADS)
Xiang, S.; Zhang, H.
2015-12-01
2D wide-angle seismic reflection/refraction survey has been widely used to investigate crustal structure and Moho topography. Similarly gravity survey is also very important in the study of local and regional earth features. Seismic survey is sensitive to the seismic velocity parameters and interface variations. For gravity survey, it is sensitive to density parameters of the medium but the resolution along the vertical direction is relatively poor. In this study, we have developed a strategy to jointly invert for seismic velocity model, density model and interface positions using the gravity observations and seismic arrival times from different phases. For the joint inversion of seismic and gravity data, it often relies on the empirical relationship between seismic velocity and density. In comparison, our joint inversion strategy also includes the cross-gradient based structure constraint for seismic velocity and density models in addition to the empirical relationship between them. The objective function for the joint inversion includes data misfit terms for seismic travel times and gravity observations, the cross-gradient constraint, the smoothness terms for two models, and the data misfit term between predicted gravity data based on density model converted from velocity model using the empirical relationship. Each term has its respective weight. We have applied the new joint inversion method to the Riwoqe-Yushu-Maduo profile in northwest China. The profile crosses through the Qiangtang block and Bayan Har block from southwest to northeast, respectively. The 2010 Ms 7.1 Yushu earthquake is located on the profile, around the Ganzi-Yushu fault zone. The joint inversion produces the velocity and density models that are similar in structure and at the same time fit their respective data sets well. Compared to separate seismic inversion using seismic travel times, the joint inversion with gravity data gives a velocity model that better delineates the fault zones. Low
NASA Astrophysics Data System (ADS)
Sourbier, F.; Operto, S.; Virieux, J.
2006-12-01
We present a distributed-memory parallel algorithm for 2D visco-acoustic full-waveform inversion of wide-angle seismic data. Our code is written in fortran90 and use MPI for parallelism. The algorithm was applied to real wide-angle data set recorded by 100 OBSs with a 1-km spacing in the eastern-Nankai trough (Japan) to image the deep structure of the subduction zone. Full-waveform inversion is applied sequentially to discrete frequencies by proceeding from the low to the high frequencies. The inverse problem is solved with a classic gradient method. Full-waveform modeling is performed with a frequency-domain finite-difference method. In the frequency-domain, solving the wave equation requires resolution of a large unsymmetric system of linear equations. We use the massively parallel direct solver MUMPS (http://www.enseeiht.fr/irit/apo/MUMPS) for distributed-memory computer to solve this system. The MUMPS solver is based on a multifrontal method for the parallel factorization. The MUMPS algorithm is subdivided in 3 main steps: a symbolic analysis step that performs re-ordering of the matrix coefficients to minimize the fill-in of the matrix during the subsequent factorization and an estimation of the assembly tree of the matrix. Second, the factorization is performed with dynamic scheduling to accomodate numerical pivoting and provides the LU factors distributed over all the processors. Third, the resolution is performed for multiple sources. To compute the gradient of the cost function, 2 simulations per shot are required (one to compute the forward wavefield and one to back-propagate residuals). The multi-source resolutions can be performed in parallel with MUMPS. In the end, each processor stores in core a sub-domain of all the solutions. These distributed solutions can be exploited to compute in parallel the gradient of the cost function. Since the gradient of the cost function is a weighted stack of the shot and residual solutions of MUMPS, each processor
NASA Astrophysics Data System (ADS)
Brasse, Heinrich; Schäfer, Anja; Díaz, Daniel; Alvarado, Guillermo E.; Muñoz, Angélica; Mütschard, Lutz
2015-11-01
A long-period magnetotelluric (MT) experiment was conducted in early 2009 in western Nicaragua to study the electrical resistivity and thus fluid/melt distribution at the Central American continental margin where the Cocos plate subducts beneath the Caribbean plate. Strike analysis yields a preference direction perpendicular to the profile, with moderate deviation from two-dimensionality, however. Two-dimensional modeling maps the sediments of the Nicaraguan Depression and a high-conductivity zone in the mid-crust, slightly offset from the arc. Further conductors are modeled in the backarc. However, these features are probably artifacts when a 2-D program is applied to data which show moderate 3-D characteristics. 3-D inversion clarifies the situation, and the major remaining conductive structure is now quasi directly beneath the volcanic chain and interpreted as a deep-seated magma deposit. Conductivity in the backarc is also relatively high and may either be caused by still existing partial melts beneath the Paleocene to Miocene volcanic arcs or by related metallic deposits in the aureoles of hydrothermal alteration.
NASA Astrophysics Data System (ADS)
Escalona, A.; Sena, A.; Mann, P.
2003-12-01
We have reprocessed and reinterpreted more than 10,000 km of "Gulfrex" multi-channel 2D seismic reflection lines collected by Gulf Oil Corporation in 1972 along the northern margin of South America (offshore Venezuela and Trinidad). These digital data were donated to the University of Texas Institute for Geophysics and represent the largest single, digital reflection survey of the region. Reprocessing of these data included: format correction, filtering, post-stack multiple suppression, and fk migration. Reprocessed data were loaded and interpreted on a workstation. The data straddle a 2,000,000 km2 zone of Paleocene-Recent, time-transgressive, oblique collision between the Caribbean arc system and the passive continental margin of northern South America. Free-air, satellite gravity data shows the remarkable 1000-km-scale continuity of four basement ridges between the uncollided part of the Caribbean arc system (NS-trending Lesser Antilles arc) and the EW-trending collisional area north of Venezuela. The basement ridges involved in the Venezuelan collisional zone include: 1) Aruba-Bonaire-Curacao ridge that can be traced as a continuous feature to the Aves ridge remnant arc of the Lesser Antilles; 2) the partially inverted Blanquilla-Bonaire basin that can be traced into the Grenada back-arc basin; 3) Margarita-Los Testigos platform that can be traced to the Lesser Antilles volcanic arc; and 4) foreland basins and fold-thrust belts of eastern Venezuela (Serrania del Interior and Maturin basin) that can be traced to the Tobago forearc basin and Barbados accretionary prism. Gulfrex data document the progressive change of basinal fault systems from NS-striking normal faults formed in extensional, Lesser Antilles intra-arc settings to rotated and inverted, NE and EW-striking normal faults deformed in the collisional area north of Venezuela. Age of initial shortening of basinal areas and inversion of normal faults setting does not follow the simple, expected pattern of
Lattice Boltzmann methods for some 2-D nonlinear diffusion equations:Computational results
Elton, B.H.; Rodrigue, G.H. . Dept. of Applied Science Lawrence Livermore National Lab., CA ); Levermore, C.D. . Dept. of Mathematics)
1990-01-01
In this paper we examine two lattice Boltzmann methods (that are a derivative of lattice gas methods) for computing solutions to two two-dimensional nonlinear diffusion equations of the form {partial derivative}/{partial derivative}t u = v ({partial derivative}/{partial derivative}x D(u){partial derivative}/{partial derivative}x u + {partial derivative}/{partial derivative}y D(u){partial derivative}/{partial derivative}y u), where u = u({rvec x},t), {rvec x} {element of} R{sup 2}, v is a constant, and D(u) is a nonlinear term that arises from a Chapman-Enskog asymptotic expansion. In particular, we provide computational evidence supporting recent results showing that the methods are second order convergent (in the L{sub 1}-norm), conservative, conditionally monotone finite difference methods. Solutions computed via the lattice Boltzmann methods are compared with those computed by other explicit, second order, conservative, monotone finite difference methods. Results are reported for both the L{sub 1}- and L{sub {infinity}}-norms.
2D MHD and 1D HD Models of a Solar Flare—a Comprehensive Comparison of the Results
NASA Astrophysics Data System (ADS)
Falewicz, R.; Rudawy, P.; Murawski, K.; Srivastava, A. K.
2015-11-01
Without any doubt, solar flaring loops possess a multithread internal structure that is poorly resolved, and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause fundamental problems in numerical modeling of flaring loops, such as selection of a structure and a number of threads, and an implementation of a proper model of the energy deposition process. A set of one-dimensional (1D) hydrodynamic and two-dimensional (2D) magnetohydrodynamic models of a flaring loop are developed to compare energy redistribution and plasma dynamics in the course of a prototypical solar flare. Basic parameters of the modeled loop are set according to the progenitor M1.8 flare recorded in AR 10126 on 2002 September 20 between 09:21 UT and 09:50 UT. The nonideal 1D models include thermal conduction and radiative losses of the optically thin plasma as energy-loss mechanisms, while the nonideal 2D models take into account viscosity and thermal conduction as energy-loss mechanisms only. The 2D models have a continuous distribution of the parameters of the plasma across the loop and are powered by varying in time and space along and across the loop heating flux. We show that such 2D models are an extreme borderline case of a multithread internal structure of the flaring loop, with a filling factor equal to 1. Nevertheless, these simple models ensure the general correctness of the obtained results and can be adopted as a correct approximation of the real flaring structures.
2D MHD AND 1D HD MODELS OF A SOLAR FLARE—A COMPREHENSIVE COMPARISON OF THE RESULTS
Falewicz, R.; Rudawy, P.; Murawski, K.; Srivastava, A. K. E-mail: rudawy@astro.uni.wroc.pl E-mail: asrivastava.app@iitbhu.ac.in
2015-11-01
Without any doubt, solar flaring loops possess a multithread internal structure that is poorly resolved, and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause fundamental problems in numerical modeling of flaring loops, such as selection of a structure and a number of threads, and an implementation of a proper model of the energy deposition process. A set of one-dimensional (1D) hydrodynamic and two-dimensional (2D) magnetohydrodynamic models of a flaring loop are developed to compare energy redistribution and plasma dynamics in the course of a prototypical solar flare. Basic parameters of the modeled loop are set according to the progenitor M1.8 flare recorded in AR 10126 on 2002 September 20 between 09:21 UT and 09:50 UT. The nonideal 1D models include thermal conduction and radiative losses of the optically thin plasma as energy-loss mechanisms, while the nonideal 2D models take into account viscosity and thermal conduction as energy-loss mechanisms only. The 2D models have a continuous distribution of the parameters of the plasma across the loop and are powered by varying in time and space along and across the loop heating flux. We show that such 2D models are an extreme borderline case of a multithread internal structure of the flaring loop, with a filling factor equal to 1. Nevertheless, these simple models ensure the general correctness of the obtained results and can be adopted as a correct approximation of the real flaring structures.
NASA Astrophysics Data System (ADS)
Lohrmann, J.; Kukowski, N.; Adam, J.; Oncken, O.
2001-12-01
In this study, we attempt to identify and quantify the influence of the mechanical parameters controlling the mass transfer modes in the brittle part of tectonically erosive and accretive forearc settings. With scaled analogue sandbox experiments we studied the influence of the amount of sediment supply, the presence of mechanically weak layers as potential detachment, the properties of the subduction interface as well as the distribution of the vertical load in the wedge on both systems, the tectonically erosive and accretive. The results of the experiments without any backward material loss lead to a hierarchical control of the investigated parameters. Sediment supply is the main parameter: As soon as sediments enter the trench on top of the oceanic plate, accretive mass transfer will occur under any mechanical constraints. A non-accretive mass transfer occurs in the case of no sediment supply. Basal properties, i.e. friction and roughness of the basal subduction interface, exert a major influence on both, the accretive and the erosive systems: They determine the capability to underthrust material beneath the wedge. In non-accretive systems, significant roughness of the basal interface and therewith a high basal friction leads to tectonic erosion, whereas a smooth basal interface produces stagnant mass transfer. The presence of a weak layer has a different influence on the accretive and non-accretive mode: In an accretive system, a weak layer in the incoming sediment pile changes the mass transfer pattern from a purely frontally or dominantly basally accretive mode to contemporaneous frontal and basal accretion. In the case of tectonic erosion, the presence of a weak layer leads to higher rates of basal erosion and arcward material transport, but it does not change the general mass transfer pattern. The distribution of vertical load only influences secondary features of the forearc architecture: Topographic highs and lows in the forearc wedge, i.e. a deviation of
NASA Technical Reports Server (NTRS)
Zimmerman, Michael I.; Farrell, W. M.; Snubbs, T. J.; Halekas, J. S.
2011-01-01
Anticipating the plasma and electrical environments in permanently shadowed regions (PSRs) of the moon is critical in understanding local processes of space weathering, surface charging, surface chemistry, volatile production and trapping, exo-ion sputtering, and charged dust transport. In the present study, we have employed the open-source XOOPIC code [I] to investigate the effects of solar wind conditions and plasma-surface interactions on the electrical environment in PSRs through fully two-dimensional pattic1e-in-cell simulations. By direct analogy with current understanding of the global lunar wake (e.g., references) deep, near-terminator, shadowed craters are expected to produce plasma "mini-wakes" just leeward of the crater wall. The present results (e.g., Figure I) are in agreement with previous claims that hot electrons rush into the crater void ahead of the heavier ions, fanning a negative cloud of charge. Charge separation along the initial plasma-vacuum interface gives rise to an ambipolar electric field that subsequently accelerates ions into the void. However, the situation is complicated by the presence of the dynamic lunar surface, which develops an electric potential in response to local plasma currents (e.g., Figure Ia). In some regimes, wake structure is clearly affected by the presence of the charged crater floor as it seeks to achieve current balance (i.e. zero net current to the surface).
First results from ideal 2-D MHD reconstruction: magnetopause reconnection event seen by Cluster
NASA Astrophysics Data System (ADS)
Teh, W.-L.; Ã-. Sonnerup, B. U.
2008-09-01
We have applied a new reconstruction method (Sonnerup and Teh, 2008), based on the ideal single-fluid MHD equations in a steady-state, two-dimensional geometry, to a reconnection event observed by the Cluster-3 (C3) spacecraft on 5 July 2001, 06:23 UT, at the dawn-side Northern-Hemisphere magnetopause. The event has been previously studied by use of Grad-Shafranov (GS) reconstruction, performed in the deHoffmann-Teller frame, and using the assumption that the flow effects were either negligible or the flow was aligned with the magnetic field. Our new method allows the reconstruction to be performed in the frame of reference moving with the reconnection site (the X-line). In the event studied, this motion is tailward/equatorward at 140 km/s. The principal result of the study is that the new method functions well, generating a magnetic field map that is qualitatively similar to those obtained in the earlier GS-based reconstructions but now includes the reconnection site itself. In comparison with the earlier map by Hasegawa et al. (2004), our new map has a slightly improved ability (cc=0.979 versus cc=0.975) to predict the fields measured by the other three Cluster spacecraft, at distances from C3 ranging from 2132 km (C1) to 2646 km (C4). The new field map indicates the presence of a magnetic X-point, located some 5300 km tailward/equatorward of C3 at the time of its traversal of the magnetopause. In the immediate vicinity of the X-point, the ideal-MHD assumption breaks down, i.e. resistive and/or other effects should be included. We have circumvented this problem by an ad-hoc procedure in which we allow the axial part of convection electric field to be non-constant near the reconnection site. The new reconstruction method also provides a map of the velocity field, in which the inflow into the wedge of reconnected field lines and the plasma jet within it can be seen, and maps of the electric potential and of the electric current distribution. Even though the
ERIC Educational Resources Information Center
Brown, Malcolm
2009-01-01
Inversions are fascinating phenomena. They are reversals of the normal or expected order. They occur across a wide variety of contexts. What do inversions have to do with learning spaces? The author suggests that they are a useful metaphor for the process that is unfolding in higher education with respect to education. On the basis of…
Familial 10p trisomy resulting from a maternal pericentric inversion
Kozma, C.; Meck, J.M.
1994-02-01
The authors report a familial recombination of a pericentric inversion of chromosome 10 resulting in 2 affected relatives who had 10p trisomy and 10q monosomy with the karyotypic abnormality designated rec(10) dup p,inv(10) (p11.2q26). Both of these individuals had the typical characteristics of 10p trisomy, however, at birth the proposita had mild facial anomalies suggesting that the distinct facial characteristics may be of postnatal onset in some cases. In addition, the proposita had gastroesophageal reflux causing severe anemia. The phenotype of the patients is compared to 41 patients with 10p trisomy reported in the literature. 37 refs., 4 figs., 3 tabs.
NASA Technical Reports Server (NTRS)
Gardner, J. P.; Straughn, Amber N.; Meurer, Gerhardt R.; Pirzkal, Norbert; Cohen, Seth H.; Malhotra, Sangeeta; Rhoads, james; Windhorst, Rogier A.; Gardner, Jonathan P.; Hathi, Nimish P.; Xu, Chun; Gronwall, Caryl; Koekemoer, Anton M.; Walsh, Jeremy; diSeregoAlighieri, Sperello
2007-01-01
The Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) grism PEARS (Probing Evolution And Reionization Spectroscopically) survey provides a large dataset of low-resolution spectra from thousands of galaxies in the GOODS North and South fields. One important subset of objects in these data are emission-line galaxies (ELGs), and we have investigated several different methods aimed at systematically selecting these galaxies. Here we present a new methodology and results of a search for these ELGs in the PEARS observations of the Hubble Ultra Deep Field (HUDF) using a 2D detection method that utilizes the observation that many emission lines originate from clumpy knots within galaxies. This 2D line-finding method proves to be useful in detecting emission lines from compact knots within galaxies that might not otherwise be detected using more traditional 1D line-finding techniques. We find in total 96 emission lines in the HUDF, originating from 81 distinct "knots" within 63 individual galaxies. We find in general that [0 1111 emitters are the most common, comprising 44% of the sample, and on average have high equivalent widths (70% of [0 1111 emitters having rest-frame EW> 100A). There are 12 galaxies with multiple emitting knots; several show evidence of variations in H-alpha flux in the knots, suggesting that the differing star formation properties across a single galaxy can in general be probed at redshifts approximately greater than 0.2 - 0.4. The most prevalent morphologies are large face-on spirals and clumpy interacting systems, many being unique detections owing to the 2D method described here, thus highlighting the strength of this technique.
NASA Astrophysics Data System (ADS)
Weller, Mitchell
The Gippsland Basin is located primarily offshore Victoria, Australia (between the Australian mainland and Tasmania) approximately 200 km east of Melbourne. The formation of the east-west trending Gippsland Basin is associated with the break-up of Gondwana during the late Jurassic/early Cretaceous and the basin has endured multiple rifting and inversion events. Strong tectonic control on the sedimentary development of the basin is reflected in the deposition of several major, basin scale sequences ranging in age from the early Cretaceous to Neogene, which are usually bounded by angular unconformities. Schlumberger's Petrel software package has been used to structurally and stratigraphically interpret a basin-wide 3D seismic data set provided by the Australian Government (Geoscience Australia) and four 2D kinematic reconstruction/restorations through the basin have been completed with Midland Valley's Move software to achieve a better understanding of the structural evolution of the Gippsland Basin. Rift phase extension calculated from the restorations (5.0--10.5%) appears anomalously low to accommodate the amount of sediment that has been deposited in the basin (>10km). Distributed extension on small faults and subsidence history from backstripping are employed to answer this anomaly. The 2D restorations completed illustrate structural time relationships across the basin and allow for a minimum estimate of erosion that has occurred along the inverted northern basin margin. Differences between previous work completed by Power et al. (2001) and this study as well as several extension models and associated implications are discussed as they relate to the interpretation carried out in this study. Extension calculated from section restorations ranged from approximately 5.0--10.5%. These measured extensional values appear too low to wholly accommodate the accumulated sediment thickness in the basin. Subsidence modelling and backstripping estimates approximately 50
Comparative Results from a CFD Challenge Over a 2D Three-Element High-Lift Airfoil
NASA Technical Reports Server (NTRS)
Klausmeyer, Steven M.; Lin, John C.
1997-01-01
A high-lift workshop was held in May of 1993 at NASA Langley Research Center. A major part of the workshop centered on a blind test of various computational fluid dynamics (CFD) methods in which the flow about a two- dimensional (2D) three-element airfoil was computed without prior knowledge of the experimental data. The results of this 'blind' test revealed: (1) The Reynolds Averaged Navier-Stokes (RANS) methods generally showed less variability among codes than did potential/Euler solvers coupled with boundary-layer solution techniques. However, some of the coupled methods still provided excellent predictions. (2) Drag prediction using coupled methods agreed more closely with experiment than the RANS methods. Lift was more accurately predicted than drag for both methods. (3) The CFD methods did well in predicting lift and drag changes due to changes in Reynolds number, however, they did not perform as well when predicting lift and drag increments due to changing flap gap, (4) Pressures and skin friction compared favorably with experiment for most of the codes. (5) There was a large variability in most of the velocity profile predictions. Computational results predict a stronger siat wake than measured suggesting a missing component in turbulence modeling, perhaps curvature effects.
Acceleration results from the microwave inverse FEL experiment
NASA Astrophysics Data System (ADS)
Yoder, R. B.; Marshall, T. C.; Hirshfield, J. L.
2001-05-01
An inverse free-electron-laser accelerator has been developed, built, and operated in the microwave regime. Development of this device has been described at previous Workshops; the accelerator is driven by RF power at 2.8 GHz propagating in a smooth-walled circular waveguide surrounded by a pulsed bifilar helical undulator with tapered pitch, while an array of solenoid coils provides an axial guide magnetic field. In low-power experiments, injected electron beams at energies between 5 and 6 MeV have gained up to 0.35 MeV with minimal energy spread, and the phase sensitivity of the IFEL mechanism has been clearly demonstrated for the first time. Agreement with simulation is very good for accelerating phases, though less exact otherwise. Scaling the device to high power and high frequency is discussed.
NASA Technical Reports Server (NTRS)
Krueger, Ronald; Paris, Isbelle L.; OBrien, T. Kevin; Minguet, Pierre J.
2004-01-01
The influence of two-dimensional finite element modeling assumptions on the debonding prediction for skin-stiffener specimens was investigated. Geometrically nonlinear finite element analyses using two-dimensional plane-stress and plane-strain elements as well as three different generalized plane strain type approaches were performed. The computed skin and flange strains, transverse tensile stresses and energy release rates were compared to results obtained from three-dimensional simulations. The study showed that for strains and energy release rate computations the generalized plane strain assumptions yielded results closest to the full three-dimensional analysis. For computed transverse tensile stresses the plane stress assumption gave the best agreement. Based on this study it is recommended that results from plane stress and plane strain models be used as upper and lower bounds. The results from generalized plane strain models fall between the results obtained from plane stress and plane strain models. Two-dimensional models may also be used to qualitatively evaluate the stress distribution in a ply and the variation of energy release rates and mixed mode ratios with delamination length. For more accurate predictions, however, a three-dimensional analysis is required.
NASA Astrophysics Data System (ADS)
Barnes, T.
In this article we review numerical studies of the quantum Heisenberg antiferromagnet on a square lattice, which is a model of the magnetic properties of the undoped “precursor insulators” of the high temperature superconductors. We begin with a brief pedagogical introduction and then discuss zero and nonzero temperature properties and compare the numerical results to analytical calculations and to experiment where appropriate. We also review the various algorithms used to obtain these results, and discuss algorithm developments and improvements in computer technology which would be most useful for future numerical work in this area. Finally we list several outstanding problems which may merit further investigation.
Random weighting error estimation for the inversion result of finite-fault rupture history
NASA Astrophysics Data System (ADS)
Ai, Yin-Shuang; Zheng, Tian-Yu; He, Yu-Mei
1999-07-01
Since the non-unique solution exists in the inversion for finite-fault rupture history, the random weighting method has been used to estimate error of the inversion results in this paper. The resolution distributions of slip amplitude, rake, rupture time and rise time on the finite fault were deduced quantitatively by model calculation. By using the random weighting method, the inversion results of Taiwan Strait earthquake and Myanmar-China boundary earthquake show that the parameters related to the rupture centers of two events have the highest resolution, and the solution are the most reliable; otherwise the resolution of the slip amplitudes and rise time on the finite-fault boundary is low.
NASA Astrophysics Data System (ADS)
Adi Aizudin Bin Radin Nasirudin, Radin; Meier, Reinhard; Ahari, Carmen; Sievert, Matti; Fiebich, Martin; Rummeny, Ernst J.; No"l, Peter B.
2011-03-01
Optical imaging (OI) is a relatively new method in detecting active inflammation of hand joints of patients suffering from rheumatoid arthritis (RA). With the high number of people affected by this disease especially in western countries, the availability of OI as an early diagnostic imaging method is clinically highly relevant. In this paper, we present a newly in-house developed OI analyzing tool and a clinical evaluation study. Our analyzing tool extends the capability of existing OI tools. We include many features in the tool, such as region-based image analysis, hyper perfusion curve analysis, and multi-modality image fusion to aid clinicians in localizing and determining the intensity of inflammation in joints. Additionally, image data management options, such as the full integration of PACS/RIS, are included. In our clinical study we demonstrate how OI facilitates the detection of active inflammation in rheumatoid arthritis. The preliminary clinical results indicate a sensitivity of 43.5%, a specificity of 80.3%, an accuracy of 65.7%, a positive predictive value of 76.6%, and a negative predictive value of 64.9% in relation to clinical results from MRI. The accuracy of inflammation detection serves as evidence to the potential of OI as a useful imaging modality for early detection of active inflammation in patients with rheumatoid arthritis. With our in-house developed tool we extend the usefulness of OI imaging in the clinical arena. Overall, we show that OI is a fast, inexpensive, non-invasive and nonionizing yet highly sensitive and accurate imaging modality.-
Ahmed, M; Eller, S; Yukihara, E; Schnell, E; Ahmad, S; Akselrod, M; Hanson, O
2014-06-15
Purpose: To develop a precise 2D dose mapping technique based on the optically stimulated luminescence (OSL) from Al{sub 2}O{sub 3} films for medical applications. Methods: A 2D laser scanning reader was developed using fast F{sup +}-center (lifetime of <7 ns) and slow F-center (lifetime of 35 ms) OSL emission from newly developed Al{sub 2}O{sub 3} films (Landauer Inc.). An algorithm was developed to correct images for both material and system properties. Since greater contribution of the F??-center emission in the recorded signal increases the readout efficiency and robustness of image corrections, Al{sub 2}O{sub 3}:C,Mg film samples are being investigated in addition to Al{sub 2}O{sub 3}:C samples. Preliminary investigations include exposure of the films to a 6 MV photon beam at 10 cm depth in solid water phantom with an SSD of 100 cm, using a 10 cm × 10 cm flat field or a 4 cm × 4 cm field with a 60° wedge filter. Kodak EDR2 radiographic film and EBT2 Gafchromic film were also exposed for comparison. Results: The results indicate that the algorithm is able to correct images and calculate 2D dose. For the wedge field irradiation, the calculated dose at the center of the field was 0.9 Gy for Al{sub 2}O{sub 3}:C and 0.87 Gy for Al{sub 2}O{sub 3}:C,Mg, whereas, the delivered dose was 0.95 Gy. A good qualitative agreement of the dose profiles was obtained between the OSL films and EDR2 and EBT2 films. Laboratory tests using a beta source suggest that a large dynamic range (10{sup −2}−10{sup 2} Gy) can be achieved using this technique. Conclusion: A 2D dosimetry system and an in-house image correction algorithm were developed for 2D film dosimetry in medical applications. The system is in the preliminary stage of development, but the data demonstrates the feasibility of this approach. This work was supported by Landauer, Inc.
NASA Astrophysics Data System (ADS)
Joung Lim, Mi; Maeng, Young Jae; Fero, Arnold H.; Anderson, Stanwood L.
2016-02-01
The 2D/1D synthesis methodology has been used to calculate the fast neutron (E > 1.0 MeV) exposure to the beltline region of the reactor pressure vessel. This method uses the DORT 3.1 discrete ordinates code and the BUGLE-96 cross-section library based on ENDF/B-VI. RAPTOR-M3G (RApid Parallel Transport Of Radiation-Multiple 3D Geometries) which performs full 3D calculations was developed and is based on domain decomposition algorithms, where the spatial and angular domains are allocated and processed on multi-processor computer architecture. As compared to traditional single-processor applications, this approach reduces the computational load as well as the memory requirement per processor. Both methods are applied to surveillance test results for the Korea Standard Nuclear Plant (KSNP)-OPR (Optimized Power Reactor) 1000 MW. The objective of this paper is to compare the results of the KSNP surveillance program between 2D/1D synthesis and RAPTOR-M3G. Each operating KSNP has a reactor vessel surveillance program consisting of six surveillance capsules located between the core and the reactor vessel in the downcomer region near the reactor vessel wall. In addition to the In-Vessel surveillance program, an Ex-Vessel Neutron Dosimetry (EVND) program has been implemented. In order to estimate surveillance test results, cycle-specific forward transport calculations were performed by 2D/1D synthesis and by RAPTOR-M3G. The ratio between measured and calculated (M/C) reaction rates will be discussed. The current plan is to install an EVND system in all of the Korea PWRs including the new reactor type, APR (Advanced Power Reactor) 1400 MW. This work will play an important role in establishing a KSNP-specific database of surveillance test results and will employ RAPTOR-M3G for surveillance dosimetry location as well as positions in the KSNP reactor vessel.
NASA Astrophysics Data System (ADS)
Ducklow, H. W.; Sailley, S. F.; Stammerjohn, S. E.; Saba, G. K.; Doney, S. C.
2014-12-01
Sea ice in the Western Antarctic Peninsula (WAP) region is both highly variable and rapidly changing. In the Palmer Station region, the ice season duration has decreased by 92 days since 1978. The sea-ice changes affect ocean stratification and freshwater balance; and in turn impact every component of the polar marine ecosystem. Long-term observations from the WAP shelf region show a pattern of chlorophyll (Chl) variability with three to five years of negative Chl anomalies interrupted by one or two years of positive anomalies. Observations and results from an inverse food-web model show that these low and high Chl regimes differed significantly from each other, with high primary productivity and net community production (NCP) associated with the high Chl years and vice-versa. Gross primary production averaged 40 mmolC m-2 d-1 in the low Chl years and 100 mmolC m-2 d-1 in the high Chl years, with 30-40% going to NCP across regimes. Only the food web in the southern region in high Chl years was dominated by large phytoplankton and krill, whereas in in all other cases, foodwebs were dominated by small phytoplankton and microzooplankton. These contrasts were strongest between the northern, low Chl years and southern, high Chl years, consistent with earlier north to south observations of sea ice and ecosystem change along the WAP. The relative importance of major bulk carbon flows did not differ substantially between high and low Chl years. Both the northern/low Chl and southern/high Chl regimes had roughly equal proportions of NCP, although its composition reflected shifts in dominance by large versus small plankton. These results suggest that food webs dominated by smaller phytoplankton and grazers have pathways that funnel production into NCP, and likely, export.
Sun, Weiwei; Xie, Hui; Ji, Ji; Zhou, Xiaojie; Goltzman, David; Miao, Dengshun
2010-12-01
We used mice with targeted deletion of 25-hydroxyvitamin D 1α-hydroxylase [1α(OH)ase(-/-)] to investigate the effects of calcium and phosphorus on defects in the reproductive system of 1,25-dihydroxyvitamin D [1,25(OH)(2)D]-deficient female mice. The 1α(OH)ase(-/-) mice and their wild-type littermates were fed either a normal diet or a rescue diet (high calcium, phosphate, and lactose) starting from weaning until 3 mo of age. We then determined serum calcium and phosphorus levels, assessed gonadotropin and gonadal hormone production, and evaluated folliculogenesis, corpus luteum formation, ovarian angiogenesis, uterus development, and fertility. Results showed that hypocalcemic and hypophosphatemic female 1α(OH)ase(-/-) mice developed infertility accompanied by decreased estrogen and progestogen levels, elevated follicle-stimulating hormone and luteinizing hormone levels, defects in follicular development and corpus luteum formation, uterine hypoplasia, and decreased ovarian expression of angiogenic factors including vascular endothelial growth factor (VEGF), angiopoietin-1 and -2, and Tie-2. When serum calcium and phosphorus were normalized by the rescue diet, the defective reproductive phenotype in the female 1α(OH)ase(-/-) mice, including the dysfunction in the hypothalamic-pituitary-ovarian axis, and ovarian angiogenesis were reversed. These results indicate that the infertility seen in 1,25(OH)(2)D-deficient mice is not a direct effect of active vitamin D deficiency on the reproductive system but is an indirect effect mediated by extracellular calcium and phosphorus.
Practical Algorithm For Computing The 2-D Arithmetic Fourier Transform
NASA Astrophysics Data System (ADS)
Reed, Irving S.; Choi, Y. Y.; Yu, Xiaoli
1989-05-01
Recently, Tufts and Sadasiv [10] exposed a method for computing the coefficients of a Fourier series of a periodic function using the Mobius inversion of series. They called this method of analysis the Arithmetic Fourier Transform(AFT). The advantage of the AFT over the FN 1' is that this method of Fourier analysis needs only addition operations except for multiplications by scale factors at one stage of the computation. The disadvantage of the AFT as they expressed it originally is that it could be used effectively only to compute finite Fourier coefficients of a real even function. To remedy this the AFT developed in [10] is extended in [11] to compute the Fourier coefficients of both the even and odd components of a periodic function. In this paper, the improved AFT [11] is extended to a two-dimensional(2-D) Arithmetic Fourier Transform for calculating the Fourier Transform of two-dimensional discrete signals. This new algorithm is based on both the number-theoretic method of Mobius inversion of double series and the complex conjugate property of Fourier coefficients. The advantage of this algorithm over the conventional 2-D FFT is that the corner-turning problem needed in a conventional 2-D Discrete Fourier Transform(DFT) can be avoided. Therefore, this new 2-D algorithm is readily suitable for VLSI implementation as a parallel architecture. Comparing the operations of 2-D AFT of a MxM 2-D data array with the conventional 2-D FFT, the number of multiplications is significantly reduced from (2log2M)M2 to (9/4)M2. Hence, this new algorithm is faster than the FFT algorithm. Finally, two simulation results of this new 2-D AFT algorithm for 2-D artificial and real images are given in this paper.
Pecher, I.A.; Minshull, T.A.; Singh, S.C.; Von Huene, R.
1996-01-01
Much of our knowledge of the worldwide distribution of submarine gas hydrates comes from seismic observations of Bottom Simulating Reflectors (BSRs). Full waveform inversion has proven to be a reliable technique for studying the fine structure of BSRs using the compressional wave velocity. We applied a non-linear full waveform inversion technique to a BSR at a location offshore Peru. We first determined the large-scale features of seismic velocity variations using a statistical inversion technique to maximise coherent energy along travel-time curves. These velocities were used for a starting velocity model for the full waveform inversion, which yielded a detailed velocity/depth model in the vicinity of the BSR. We found that the data are best fit by a model in which the BSR consists of a thin, low-velocity layer. The compressional wave velocity drops from 2.15 km/s down to an average of 1.70 km/s in an 18m thick interval, with a minimum velocity of 1.62 km/s in a 6 m interval. The resulting compressional wave velocity was used to estimate gas content in the sediments. Our results suggest that the low velocity layer is a 6-18 m thick zone containing a few percent of free gas in the pore space. The presence of the BSR coincides with a region of vertical uplift. Therefore, we suggest that gas at this BSR is formed by a dissociation of hydrates at the base of the hydrate stability zone due to uplift and subsequently a decrease in pressure.
Roper, C. D.; Dunham, J. D.; Tornow, W.
2010-01-01
Measurements of the H-2(d, n)(3) He transverse vector polarization-transfer coefficient K-y(y)' at 0 degrees. are reported for 29 outgoing neutron energies between 3.94 and 8.47MeV. Our new results determine K-y(y)' (0 degrees) more accurately than previous data, especially for neutron energies below 5MeV. Low-energy data for this reaction are important both as a high-intensity source of highly polarized neutrons for nuclear physics studies with polarized neutron beams, and as a test of the emerging theoretical descriptions of the four-body system, where recently substantial progress has been made.
Niedermaier, Michael; Schwabe, Georg C; Fees, Stephan; Helmrich, Anne; Brieske, Norbert; Seemann, Petra; Hecht, Jochen; Seitz, Volkhard; Stricker, Sigmar; Leschik, Gundula; Schrock, Evelin; Selby, Paul B; Mundlos, Stefan
2005-04-01
Short digits (Dsh) is a radiation-induced mouse mutant. Homozygous mice are characterized by multiple defects strongly resembling those resulting from Sonic hedgehog (Shh) inactivation. Heterozygous mice show a limb reduction phenotype with fusion and shortening of the proximal and middle phalanges in all digits, similar to human brachydactyly type A1, a condition caused by mutations in Indian hedgehog (IHH). We mapped Dsh to chromosome 5 in a region containing Shh and were able to demonstrate an inversion comprising 11.7 Mb. The distal breakpoint is 13.298 kb upstream of Shh, separating the coding sequence from several putative regulatory elements identified by interspecies comparison. The inversion results in almost complete downregulation of Shh expression during E9.5-E12.5, explaining the homozygous phenotype. At E13.5 and E14.5, however, Shh is upregulated in the phalangeal anlagen of Dsh/+ mice, at a time point and in a region where WT Shh is never expressed. The dysregulation of Shh expression causes the local upregulation of hedgehog target genes such as Gli1-3, patched, and Pthlh, as well as the downregulation of Ihh and Gdf5. This results in shortening of the digits through an arrest of chondrocyte differentiation and the disruption of joint development.
Stembalska, Agnieszka; Laczmanska, Izabela; Schlade-Bartusiak, Kamila; Czemarmazowicz, Halina; Murawski, Marek; Sasiadek, Maria
2007-01-01
The chromosome 4 inversion with breakpoints p13-p15q35 results in a recombinant 4 [rec(4)] chromosome with a partial 4p duplication/4q deletion in approximately 80% of the carriers' offspring. However, whether the recombinant 4p syndrome can be recognized as a clinical entity is still open to controversy. We report on two sisters diagnosed with rec(4) resulting in a partial 4p trisomy/4q deletion that was inherited from their mother, who is a carrier of inv(4)(p14q35). Both probands presented phenotypes consistent with those observed in other children with rec(4)parental, supporting the proposal that the rec(4)parental syndrome is a distinct entity among dup(4p) cases and may be suspected on the basis of the pattern of clinical symptoms. To the best of our knowledge this is only the second report of family with two probands affected with a recombinant chromosome 4 arising from a parental pericentric inversion.
NASA Astrophysics Data System (ADS)
Noh, K.; Jeong, S.; Seol, S. J.; Byun, J.; Kwon, T.
2015-12-01
Man-made carbon dioxide (CO2) released into the atmosphere is a significant contributor to the greenhouse gas effect and related global warming. Sequestration of CO2 into saline aquifers has been proposed as one of the most practical options of all geological sequestration possibilities. During CO2 geological sequestration, monitoring is indispensable to delineate the change of CO2 saturation and migration of CO2 in the subsurface. Especially, monitoring of CO2 saturation in aquifers provides useful information for determining amount of injected CO2. Seismic inversion can provide the migration of CO2 plume with high resolution because velocity is reduced when CO2 replaces the pore fluid during CO2 injection. However, the estimation of CO2 saturation using the seismic method is difficult due to the lower sensitivity of the velocity to the saturation when the CO2 saturation up to 20%. On the other hand, marine controlled-source EM (mCSEM) inversion is sensitive to the resistivity changes resulting from variations in CO2 saturation, even though it has poor resolution than seismic method. In this study, we proposed an effective CO2 sequestration monitoring method using joint inversion of seismic and mCSEM data based on a cross-gradient constraint. The method was tested with realistic CO2 injection models in a deep brine aquifer beneath a shallow sea which is selected with consideration for the access convenience for the installation of source and receiver and an environmental safety. Resistivity images of CO2 plume by the proposed method for different CO2 injection stages have been significantly improved over those obtained from individual EM inversion. In addition, we could estimate a reliable CO2 saturation by rock physics model (RPM) using the P-wave velocity and the improved resistivity. The proposed method is a basis of three-dimensional estimation of reservoir parameters such as porosity and fluid saturation, and the method can be also applied for detecting a
NASA Astrophysics Data System (ADS)
Insfrán, J. F.; Ubal, S.; Di Paolo, y. J.
2016-04-01
A simplified model of a proximal convoluted tubule of an average human nephron is presented. The model considers the 2D axisymmetric flow of the luminal solution exchanging matter with the tubule walls and the peritubular fluid by means of 0D models for the epithelial cells. The tubule radius is considered to vary along the conduit due to the trans-epithelial pressure difference. The fate of more than ten typical solutes is tracked down by the model. The Navier-Stokes and Reaction-Diffusion-Advection equations (considering the electro-neutrality principle) are solved in the lumen, giving a detailed picture of the velocity, pressure and concentration fields, along with trans-membrane fluxes and tubule deformation, via coupling with the 0D model for the tubule wall. The calculations are carried out numerically by means of the finite element method. The results obtained show good agreement with those published by other authors using models that ignore the diffusive transport and disregard a detailed calculation of velocity, pressure and concentrations. This work should be seen as a first approach towards the development of a more comprehensive model of the filtration process taking place in the kidneys, which ultimately helps in devising a device that can mimic/complement the renal function.
James, O.B.; Floss, C.; McGee, J.J.
2002-01-01
We present results of a secondary ion mass spectrometry study of the rare earth elements (REEs) in the minerals of two samples of lunar ferroan anorthosite, and the results are applicable to studies of REEs in all igneous rocks, no matter what their planet of origin. Our pyroxene analyses are used to determine solid-solid REE distribution coefficients (D = CREE in low-Ca pyroxene/CREE in augite) in orthopyroxene-augite pairs derived by inversion of pigeonite. Our data and predictions from crystal-chemical considerations indicate that as primary pigeonite inverts to orthopyroxene plus augite and subsolidus reequilibration proceeds, the solid-solid Ds for orthopyroxene-augite pairs progressively decrease for all REEs; the decrease is greatest for the LREEs. The REE pattern of solid-solid Ds for inversion-derived pyroxene pairs is close to a straight line for Sm-Lu and turns upward for REEs lighter than Sm; the shape of this pattern is predicted by the shapes of the REE patterns for the individual minerals. Equilibrium liquids calculated for one sample from the compositions of primary phases, using measured or experimentally determined solid-liquid Ds, have chondrite-normalized REE patterns that are very slightly enriched in LREEs. The plagioclase equilibrium liquid is overall less rich in REEs than pyroxene equilibrium liquids, and the discrepancy probably arises because the calculated plagioclase equilibrium liquid represents a liquid earlier in the fractionation sequence than the pyroxene equilibrium liquids. "Equilibrium" liquids calculated from the compositions of inversion-derived pyroxenes or orthopyroxene derived by reaction of olivine are LREE depleted (in some cases substantially) in comparison with equilibrium liquids calculated from the compositions of primary phases. These discrepancies arise because the inversion-derived and reaction-derived pyroxenes did not crystallize directly from liquid, and the use of solid-liquid Ds is inappropriate. The LREE
Planktonic food webs revisited: Reanalysis of results from the linear inverse approach
NASA Astrophysics Data System (ADS)
Hlaili, Asma Sakka; Niquil, Nathalie; Legendre, Louis
2014-01-01
Identification of the trophic pathway that dominates a given planktonic assemblage is generally based on the distribution of biomasses among food-web compartments, or better, the flows of materials or energy among compartments. These flows are obtained by field observations and a posteriori analyses, including the linear inverse approach. In the present study, we re-analysed carbon flows obtained by inverse analysis at 32 stations in the global ocean and one large lake. Our results do not support two "classical" views of plankton ecology, i.e. that the herbivorous food web is dominated by mesozooplankton grazing on large phytoplankton, and the microbial food web is based on microzooplankton significantly consuming bacteria; our results suggest instead that phytoplankton are generally grazed by microzooplankton, of which they are the main food source. Furthermore, we identified the "phyto-microbial food web", where microzooplankton largely feed on phytoplankton, in addition to the already known "poly-microbial food web", where microzooplankton consume more or less equally various types of food. These unexpected results led to a (re)definition of the conceptual models corresponding to the four trophic pathways we found to exist in plankton, i.e. the herbivorous, multivorous, and two types of microbial food web. We illustrated the conceptual trophic pathways using carbon flows that were actually observed at representative stations. The latter can be calibrated to correspond to any field situation. Our study also provides researchers and managers with operational criteria for identifying the dominant trophic pathway in a planktonic assemblage, these criteria being based on the values of two carbon ratios that could be calculated from flow values that are relatively easy to estimate in the field.
Gu, Dasa; Wang, Yuhang; Smeltzer, Charles; Boersma, K. Folkert
2014-06-27
Inverse modeling using satellite observations of nitrogen dioxide (NO2) columns has been extensively used to estimate nitrogen oxides (NOx) emissions in China. Recently, the Global Ozone Monitoring Experiment-2 (GOME-2) and Ozone Monitoring Instrument (OMI) provide independent global NO2 column measurements on a nearly daily basis at around 9:30 and 13:30 local time across the equator, respectively. Anthropogenic NOx emission estimates by applying previously developed monthly inversion (MI) or daily inversion (DI) methods to these two sets of measurements show substantial differences. We improve the DI method by conducting model simulation, satellite retrieval, and inverse modeling sequentially on a daily basis. After each inversion, we update anthropogenic NOx emissions in the model simulation with the newly obtained a posteriori results. Consequently, the inversion-optimized emissions are used to compute the a priori NO2 profiles for satellite retrievals. As such, the a priori profiles used in satellite retrievals are now coupled to inverse modeling results. The improved procedure was applied to GOME-2 and OMI NO2 measurements in 2011. The new daily retrieval-inversion (DRI) method estimates an average NOx emission of 6.9 Tg N/yr over China, and the difference between using GOME-2 and OMI measurements is 0.4 Tg N/yr, which is significantly smaller than the difference of 1.3 Tg N/yr using the previous DI method. Using the more consistent DRI inversion results, we find that anthropogenic NOx emissions tend to be higher in winter and summer than spring (and possibly fall) and the weekday-to-weekend emission ratio tends to increase with NOx emission in China.
Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.; Aeschlimann, R. W.; Basu, S.
2011-05-23
The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of a third long-term 2-D Core-Concrete Interaction (CCI) experiment designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-3 experiment, which was conducted on September 22, 2005. Test specifications for CCI-3 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 375
Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.; Aeschlimann, R. W.; Basu, S.
2011-05-23
The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-2 experiment, which was conducted on August 24, 2004. Test specifications for CCI-2 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 400 kg
Farmer, M. T.; Lomperski, S.; Aeschlimann, R. W.; Basu, S.
2011-05-23
The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten coreconcrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-1 experiment, which was conducted on December 19, 2003. Test specifications for CCI-1 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 400 kg
Nutter, C.
1980-11-01
GRAV2D is an interactive computer program used for modeling 2-1/2 dimensional gravity data. A forward algorithm is used to give the theoretical attraction of gravity intensity at a station due to a perturbing body given by the initial model. The resultant model can then be adjusted for a better fit by a combination of manual adjustment, one-dimensional automatic search, and Marquardt inversion. GRAV2D has an interactive data management system for data manipulation and display built around subroutines to do a forward problem, a one-dimensional direct search and an inversion. This is a user's guide and documentation for GRAV2D.
NASA Technical Reports Server (NTRS)
Fralick, Gustave C.; Decker, Arthur J.; Blue, James W.
1989-01-01
An experiment was performed to look for evidence of deuterium fusion in palladium. The experiment, which involved introducing deuterium into the palladium filter of a hydrogen purifier, was designed to detect neutrons produced in the reaction D-2 + D-2 yields He-3 + n as well as heat production. The neutron counts for deuterium did not differ significantly from background or from the counts for a hydrogen control. Heat production was detected when deuterium, but not hydrogen, was pumped from the purifier.
Numerical simulation of ( T 2, T 1) 2D NMR and fluid responses
NASA Astrophysics Data System (ADS)
Tan, Mao-Jin; Zou, You-Long; Zhang, Jin-Yan; Zhao, Xin
2012-12-01
One-dimensional nuclear magnetic resonance (1D NMR) logging technology is limited for fluid typing, while two-dimensional nuclear magnetic resonance (2D NMR) logging can provide more parameters including longitudinal relaxation time ( T 1) and transverse relaxation time ( T 2) relative to fluid types in porous media. Based on the 2D NMR relaxation mechanism in a gradient magnetic field, echo train simulation and 2D NMR inversion are discussed in detail. For 2D NMR inversion, a hybrid inversion method is proposed based on the damping least squares method (LSQR) and an improved truncated singular value decomposition (TSVD) algorithm. A series of spin echoes are first simulated with multiple waiting times ( T W s) in a gradient magnetic field for given fluid models and these synthesized echo trains are inverted by the hybrid method. The inversion results are consistent with given models. Moreover, the numerical simulation of various fluid models such as the gas-water, light oil-water, and vicious oil-water models were carried out with different echo spacings ( T E s) and T W s by this hybrid method. Finally, the influences of different signal-to-noise ratios (SNRs) on inversion results in various fluid models are studied. The numerical simulations show that the hybrid method and optimized observation parameters are applicable to fluid typing of gas-water and oil-water models.
Sparse radar imaging using 2D compressed sensing
NASA Astrophysics Data System (ADS)
Hou, Qingkai; Liu, Yang; Chen, Zengping; Su, Shaoying
2014-10-01
Radar imaging is an ill-posed linear inverse problem and compressed sensing (CS) has been proved to have tremendous potential in this field. This paper surveys the theory of radar imaging and a conclusion is drawn that the processing of ISAR imaging can be denoted mathematically as a problem of 2D sparse decomposition. Based on CS, we propose a novel measuring strategy for ISAR imaging radar and utilize random sub-sampling in both range and azimuth dimensions, which will reduce the amount of sampling data tremendously. In order to handle 2D reconstructing problem, the ordinary solution is converting the 2D problem into 1D by Kronecker product, which will increase the size of dictionary and computational cost sharply. In this paper, we introduce the 2D-SL0 algorithm into the reconstruction of imaging. It is proved that 2D-SL0 can achieve equivalent result as other 1D reconstructing methods, but the computational complexity and memory usage is reduced significantly. Moreover, we will state the results of simulating experiments and prove the effectiveness and feasibility of our method.
NASA Astrophysics Data System (ADS)
Vaughan-Hirsch, David
2013-04-01
Glacitectonic rafts are defined as dislocated slabs of bedrock or unconsolidated sediments, transported from their original position by glacial action. These relatively thin, slab-like bodies feature transport distances ranging from tens of meters to hundreds of kilometers. They occur as either single rafts, or multiple stacked bodies associated with a variety of ice-pushed landforms. Internally, rafts frequently appear undeformed although at a larger scale, they may be folded or cut by shear zones and brittle faults. However, the processes leading to the detachment, transport and subsequent emplacement of the rafts remain uncertain. This work describes the results of a geophysical 2D seismic survey of thrust-bound glacitectonic rafts and associated deformation structures, occurring within mid-Pleistocene glacigenic sediments of the Central Graben, central North Sea. The total shortened length of the rafted section is 2.4km, comprising a series of nine discrete rafts which individually range from 235m to 1018m in length. The principle basal detachment occurs at the erosive contact between Aberdeen Ground Formation and overlying Ling Bank Formation. The ice-proximal (northern) limit of rafting is defined by the presence of a large-scale palaeo-channel oriented perpendicular to the direction of rafting, composed of sediments of the Ling Bank Formation and the Forth Formation. The observed deformation structures infer a mean tectonic direction of 178°, indicating that they are associated with an active glacial advance from the north. The resulting deformation creates a minimum lateral shortening throughout the observed sequence of 35%, typifying a strongly compressional regieme associated with rafting. Throughout the surveyed area, structurally younger rafts are found to be emplaced towards the south, compared to the structurally older rafts which are emplaced towards the south-east. This distinction is suggested to be caused by early rafts creating an obstacle to
NASA Astrophysics Data System (ADS)
Haines, S. S.; Hart, P. E.; Shedd, W. W.; Frye, M.; Agena, W.; Miller, J. J.; Ruppel, C. D.
2013-12-01
In the spring of 2013, the U.S. Geological Survey led a 16-day seismic acquisition cruise aboard the R/V Pelican in the Gulf of Mexico to survey two established gas hydrate study sites. We used a pair of 105/105 cubic inch generator/injector airguns as the seismic source, and a 450-m 72-channel hydrophone streamer to record two-dimensional (2D) data. In addition, we also deployed at both sites an array of 4-component ocean-bottom seismometers (OBS) to record P- and S-wave energy at the seafloor from the same seismic source positions as the streamer data. At lease block Green Canyon 955 (GC955), we acquired 400 km of 2-D streamer data, in a 50- to 250-m-spaced grid augmented by several 20-km transects that provide long offsets for the OBS. The seafloor recording at GC955 was accomplished by a 2D array of 21 OBS at approximately 400-m spacing, including instruments carefully positioned at two of the three boreholes where extensive logging-while-drilling data is available to characterize the presence of gas hydrate. At lease block Walker Ridge 313 (WR313), we acquired 450 km of streamer data in a set of 11-km, 150- to 1,000-m-spaced, dip lines and 6- to 8-km, 500- to 1000-m-spaced strike lines. These were augmented by a set of 20-km lines that provide long offsets for a predominantly linear array of 25 400- to 800-m spaced OBS deployed in the dip direction in and around WR313. The 2D data provide at least five times better resolution of the gas hydrate stability zone than the available petroleum industry seismic data from the area; this enables considerably improved analysis and interpretation of stratigraphic and structural features including previously unseen faults and gas chimneys that may have considerable impact on gas migration. Initial processing indicates that the OBS data quality is good, and we anticipate that these data will yield estimates of P- and S-wave velocities, as well as PP (reflected) and PS (converted wave) images beneath each sensor location.
NASA Astrophysics Data System (ADS)
Merkel, Ronny; Gruhn, Stefan; Dittmann, Jana; Vielhauer, Claus; Bräutigam, Anja
2012-03-01
Determining the age of latent fingerprint traces found at crime scenes is an unresolved research issue since decades. Solving this issue could provide criminal investigators with the specific time a fingerprint trace was left on a surface, and therefore would enable them to link potential suspects to the time a crime took place as well as to reconstruct the sequence of events or eliminate irrelevant fingerprints to ensure privacy constraints. Transferring imaging techniques from different application areas, such as 3D image acquisition, surface measurement and chemical analysis to the domain of lifting latent biometric fingerprint traces is an upcoming trend in forensics. Such non-destructive sensor devices might help to solve the challenge of determining the age of a latent fingerprint trace, since it provides the opportunity to create time series and process them using pattern recognition techniques and statistical methods on digitized 2D, 3D and chemical data, rather than classical, contact-based capturing techniques, which alter the fingerprint trace and therefore make continuous scans impossible. In prior work, we have suggested to use a feature called binary pixel, which is a novel approach in the working field of fingerprint age determination. The feature uses a Chromatic White Light (CWL) image sensor to continuously scan a fingerprint trace over time and retrieves a characteristic logarithmic aging tendency for 2D-intensity as well as 3D-topographic images from the sensor. In this paper, we propose to combine such two characteristic aging features with other 2D and 3D features from the domains of surface measurement, microscopy, photography and spectroscopy, to achieve an increase in accuracy and reliability of a potential future age determination scheme. Discussing the feasibility of such variety of sensor devices and possible aging features, we propose a general fusion approach, which might combine promising features to a joint age determination scheme
Shapira, S.K.; Gagos, S.; Shaffer, L.G.
1997-04-14
We report on a case of constitutional mosaicism for a large pericentric inversion of chromosome 9 in a man whose daughter had recombinant aneusomy resulting in partial 9q duplication and partial 9p deletion. At age 6 months, the girl was evaluated because of dysmorphic congenital animal features and developmental delay. Chromosomal analysis on this infant showed a derivative chromosome 9 which was later determined to be a recombinant chromosome with trisomy of 9q34.1{r_arrow}qter and monosomy of pter{r_arrow}9p24. Chromosomal analysis in her father showed the presence of two cell lines; 75% of lymphocytes had a 46,XY pattern, and 25% had a 46,XY,inv(9)(p24q34.1) karyotype. The infant`s physical findings represent a composite of the reported cases of both trisomy 9q34.1{r_arrow}qter and monosomy pter{r_arrow}p24. The infant`s father was phenotypically and cognitively normal. This case broadens the spectrum of reported cases of mosaicism for an autosomal structural rearrangement generating unbalanced gametes, and further supports the tenet that constitutional mosaicism has clinical relevance for genetic counseling. 21 refs., 3 figs., 1 tab.
2005-07-01
Aniso2d is a two-dimensional seismic forward modeling code. The earth is parameterized by an X-Z plane in which the seismic properties Can have monoclinic with x-z plane symmetry. The program uses a user define time-domain wavelet to produce synthetic seismograms anrwhere within the two-dimensional media.
NASA Astrophysics Data System (ADS)
Jang, Hyun-Sook; Yu, Changqian; Hayes, Robert; Granick, Steve
2015-03-01
Polymer vesicles (``polymersomes'') are an intriguing class of soft materials, commonly used to encapsulate small molecules or particles. Here we reveal they can also effectively incorporate nanoparticles inside their polymer membrane, leading to novel ``2D nanocomposites.'' The embedded nanoparticles alter the capacity of the polymersomes to bend and to stretch upon external stimuli.
Albu, Jeanine B.; Lu, Jiang; Mooradian, Arshag D.; Krone, Ronald J.; Nesto, Richard W.; Porter, Marty H.; Rana, Jamal S.; Rogers, William J.; Sobel, Burton E.; Gottlieb, Sheldon H.
2015-01-01
The impact of obesity on cardiovascular disease (CVD) outcomes in patients with type 2 diabetes mellitus (T2DM) and established coronary artery disease (CAD) is controversial; whether BMI and/or waist circumference correlate with atherothrombotic risk factors in such patients is uncertain. We sought to evaluate whether higher BMI or waist circumference are associated with specific risk factors among 2,273 Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) study participants with T2DM and documented CAD (baseline data, mean age 62 years, 66% non-Hispanic white, 71% men). Multiple linear regression models were constructed after adjusting for sex, age, race/ ethnicity, US vs. non-US site, diabetes duration, exercise, smoking, alcohol, and relevant medication use. First-order partial correlations of BMI with risk factors after controlling for waist circumference and of waist circumference with risk factors after controlling for BMI were also evaluated. Ninety percent of the patients were overweight (BMI ≥25 kg/m2); 68% of men and 89% of women had high-risk waist circumference measures (≥102 and ≥88 cm, respectively). BMI and waist circumference, in separate models, explained significant variation in metabolic (insulin, lipids, blood pressure (BP)) and inflammatory/procoagulation (C-reactive protein, PAI-1 activity and antigen, and fibrinogen) risk factors. In partial correlation analyses BMI was independently associated with BP and inflammatory/procoagulation factors, waist circumference with lipids, and both BMI and waist circumference with insulin. We conclude that, in cross-sectional analyses, both BMI and waist circumference, independently, are associated with increased atherothrombotic risk in centrally obese cohorts such as the BARI 2D patients with T2DM and CAD. PMID:19875998
2011-12-31
Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j0) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assignsmore » an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations.« less
NASA Technical Reports Server (NTRS)
Goel, N.; Strebel, D. E.
1983-01-01
An important but relatively uninvestigated problem in remote sensing is the inversion of vegetative canopy reflectance models to obtain agrophysical parameters, given measured reflectances. The problem is here formally defined and its solution outlined. Numerical nonlinear optimization techniques are used to implement this inversion to obtain the leaf area index using Suits' canopy reflectance model. The results for a variety of cases indicate that this can be done successfully using infrared reflectances at different views or azimuth angles or a combination thereof. The other parameters of the model must be known, although reasonable measurement errors can be tolerated without seriously degrading the accuracy of the inversion. The application of the technique to ground based remote-sensing experiments is potentially useful, but is limited to the degree to which the canopy reflectance model can accurately predict observed reflectances.
NASA Astrophysics Data System (ADS)
Ferreira, C.; Gonzalez, A.; Baldacchino, D.; Aparicio, M.; Gómez, S.; Munduate, X.; Garcia, N. R.; Sørensen, J. N.; Jost, E.; Knecht, S.; Lutz, T.; Chassapogiannis, P.; Diakakis, K.; Papadakis, G.; Voutsinas, S.; Prospathopoulos, J.; Gillebaart, T.; van Zuijlen, A.
2016-09-01
The FP7 AdVanced Aerodynamic Tools for lArge Rotors - Avatar project aims to develop and validate advanced aerodynamic models, to be used in integral design codes for the next generation of large scale wind turbines (10-20MW). One of the approaches towards reaching rotors for 10-20MW size is the application of flow control devices, such as flaps. In Task 3.2: Development of aerodynamic codes for modelling of flow devices on aerofoils and, rotors of the Avatar project, aerodynamic codes are benchmarked and validated against the experimental data of a DU95W180 airfoil in steady and unsteady flow, for different angle of attack and flap settings, including unsteady oscillatory trailing-edge-flap motion, carried out within the framework of WP3: Models for Flow Devices and Flow Control, Task 3.1: CFD and Experimental Database. The aerodynamics codes are: AdaptFoil2D, Foil2W, FLOWer, MaPFlow, OpenFOAM, Q3UIC, ATEFlap. The codes include unsteady Eulerian CFD simulations with grid deformation, panel models and indicial engineering models. The validation cases correspond to 18 steady flow cases, and 42 unsteady flow cases, for varying angle of attack, flap deflection and reduced frequency, with free and forced transition. The validation of the models show varying degrees of agreement, varying between models and flow cases.
Full seismic waveform inversion of the African crust and Mantle - Initial Results
NASA Astrophysics Data System (ADS)
Afanasiev, Michael; Ermert, Laura; Staring, Myrna; Trampert, Jeannot; Fichtner, Andreas
2016-04-01
We report on the progress of a continental-scale full-waveform inversion (FWI) of Africa. From a geodynamic perspective, Africa presents an especially interesting case. This interest stems from the presence of several anomalous features such as a triple junction in the Afar region, a broad region of high topography to the south, and several smaller surface expressions such as the Cameroon Volcanic Line and Congo Basin. The mechanisms behind these anomalies are not fully clear, and debate on their origin spans causative mechanisms from isostatic forcing, to the influence of localized asthenospheric upwelling, to the presence of deep mantle plumes. As well, the connection of these features to the African LLSVP is uncertain. Tomographic images of Africa present unique challenges due to uneven station coverage: while tectonically active areas such as the Afar rift are well sampled, much of the continent exhibits a severe dearth of seismic stations. As well, while mostly surrounded by tectonically active spreading plate boundaries (a fact which contributes to the difficulties in explaining the South's high topography), sizeable seismic events (M > 5) in the continent's interior are relatively rare. To deal with these issues, we present a combined earthquake and ambient noise full-waveform inversion of Africa. The noise component serves to boost near-surface sensitivity, and aids in mitigating issues related to the sparse source / station coverage. The earthquake component, which includes local and teleseismic sources, aims to better resolve deeper structure. This component also has the added benefit of being especially useful in the search for mantle plumes: synthetic tests have shown that the subtle scattering of elastic waves off mantle plumes makes the plumes an ideal target for FWI [1]. We hope that this new model presents a fresh high-resolution image of sub-African geodynamic structure, and helps advance the debate regarding the causative mechanisms of its surface
Staring 2-D hadamard transform spectral imager
Gentry, Stephen M.; Wehlburg, Christine M.; Wehlburg, Joseph C.; Smith, Mark W.; Smith, Jody L.
2006-02-07
A staring imaging system inputs a 2D spatial image containing multi-frequency spectral information. This image is encoded in one dimension of the image with a cyclic Hadamarid S-matrix. The resulting image is detecting with a spatial 2D detector; and a computer applies a Hadamard transform to recover the encoded image.
Sen, Sabyasachi; Kaseman, Derrick C; Colas, Bruno; Jacob, Dorrit E; Clark, Simon M
2016-07-27
Systematic correlation in alkaline-earth carbonate compounds between the deviation of the CO3 units from the perfect D3h symmetry and their (13)C nuclear magnetic resonance (NMR) chemical shift anisotropy (CSA) parameters is established. The (13)C NMR CSA parameters of amorphous calcium carbonate (ACC) are measured using two-dimensional (13)C phase adjusted spinning sidebands (PASS) NMR spectroscopy and are analyzed on the basis of this correlation. The results indicate a distortion of the CO3 units in ACC in the form of an in-plane displacement of the C atom away from the centroid of the O3 triangle, resulting from hydrogen bonding with the surrounding H2O molecules, without significant out-of-plane displacement. Similar distortion for all C atoms in the structure of ACC suggests a uniform spatial disposition of H2O molecules around the CO3 units forming a hydrogen-bonded amorphous network. This amorphous network is stabilized against crystallization by steric frustration, while additives such as Mg presumably provide further stabilization by increasing the energy of dehydration. PMID:27276013
NASA Astrophysics Data System (ADS)
Potter, Kelsey A.; Buck, Amy C.; Self, Wade K.; Capadona, Jeffrey R.
2012-08-01
An estimated 25 million people in the US alone rely on implanted medical devices, ˜2.5 million implanted within the nervous system. Even though many devices perform adequately for years, the host response to medical devices often severely limits tissue integration and long-term performance. This host response is believed to be particularly limiting in the case of intracortical microelectrodes, where it has been shown that glial cell encapsulation and localized neuronal cell loss accompany intracortical microelectrode implantation. Since neuronal ensembles must be within ˜50 µm of the electrode to obtain neuronal spikes and local field potentials, developing a better understanding of the molecular and cellular environment at the device-tissue interface has been the subject of significant research. Unfortunately, immunohistochemical studies of scar maturation in correlation to device function have been inconclusive. Therefore, here we present a detailed quantitative study of the cellular events and the stability of the blood-brain barrier (BBB) following intracortical microelectrode implantation and cortical stab injury in a chronic survival model. We found two distinctly inverse multiphasic profiles for neuronal survival in device-implanted tissue compared to stab-injured animals. For chronically implanted animals, we observed a biphasic paradigm between blood-derived/trauma-induced and CNS-derived inflammatory markers driving neurodegeneration at the interface. In contrast, stab injured animals demonstrated a CNS-mediated neurodegenerative environment. Collectively these data provide valuable insight to the possibility of multiple roles of chronic neuroinflammatory events on BBB disruption and localized neurodegeneration, while also suggesting the importance to consider multiphasic neuroinflammatory kinetics in the design of therapeutic strategies for stabilizing neural interfaces.
Plasma adiponectin is inversely associated with antenatal anxiety: Results from a Brazilian cohort.
Rebelo, Fernanda; de Jesus Pereira Pinto, Thatiana; Franco-Sena, Ana Beatriz; Lepsch, Jaqueline; Benaim, Camila; Struchiner, Claudio José; Kac, Gilberto
2015-01-01
Antenatal anxiety may increase the risk of undesirable birth outcomes. Studies have demonstrated an association between adiponectin and anxiety, but this issue has not been investigated during pregnancy. This study aimed to evaluate the association between plasma adiponectin, measured throughout gestation, and the occurrence of anxiety at late pregnancy (30-36th weeks). A prospective cohort was investigated in Rio de Janeiro, Brazil. Healthy pregnant women, aged 20-40 years, were evaluated between gestational weeks 5-13, 22-26 and 30-36. State anxiety was measured using a validated version of the State-Trait Anxiety Inventory, and women were categorized as high (score≥50, n=30) or low anxiety (score<50, n=129). Plasma samples for all trimesters were analyzed using commercial ELISA kits to determine adiponectin concentrations (U/mL). Statistical analysis involved student's t-tests, chi-square, Pearson correlation, multiple logistic regression and linear mixed effects (LME) regression to model longitudinal trends of adiponectin, stratified for anxiety categories. Women with higher anxiety scores had lower mean concentrations of 3rd trimester adiponectin compared with those with lower scores (7.9; 95% CI: 7.0-8.9 vs. 9.9; 95% CI: 9.1-10.7). Women with 3rd trimester adiponectin values within the third tertile (10.47-26.57U/mL) were less likely to have high antenatal anxiety (adjusted OR=0.30; 95% CI: 0.09-0.98) compared with those within the first tertile (2.25-7.08U/mL). Unlike women with low levels of anxiety, those with high levels had a significant decrease of plasma adiponectin throughout pregnancy (β=-0.07; 95% CI: -0.13-[-0.01] vs. β=-0.01; 95% CI: -0.05 to 0.03). Multiple LME model indicated higher adiponectin throughout pregnancy for women with low anxiety (β=-1.57; 95% CI: -2.78-[-0.37]). In conclusion, plasma adiponectin throughout pregnancy was inversely associated with antenatal anxiety. PMID:25305545
Rohadi, Supriyanto; Widiyantoro, Sri; Nugraha, Andri Dian; Masturyono
2013-09-09
The realization of local earthquake tomography is usually conducted by removing distant events outside the study region, because these events may increase errors. In this study, tomographic inversion has been conducted using the travel time data of local and regional events in order to improve the structural resolution, especially for deep structures. We used the local MERapi Amphibious EXperiments (MERAMEX) data catalog that consists of 292 events from May to October 2004. The additional new data of regional events in the Java region were taken from the Meteorological, Climatological, and Geophysical Agency (MCGA) of Indonesia, which consist of 882 events, having at least 10 recording phases at each seismographic station from April 2009 to February 2011. We have conducted joint inversions of the combined data sets using double-difference tomography to invert for velocity structures and to conduct hypocenter relocation simultaneously. The checkerboard test results of Vp and Vs structures demonstrate a significantly improved spatial resolution from the shallow crust down to a depth of 165 km. Our tomographic inversions reveal a low velocity anomaly beneath the Lawu - Merapi zone, which is consistent with the results from previous studies. A strong velocity anomaly zone with low Vp, low Vs and low Vp/Vs is also identified between Cilacap and Banyumas. We interpret this anomaly as a fluid content material with large aspect ratio or sediment layer. This anomaly zone is in a good agreement with the existence of a large dome containing sediment in this area as proposed by previous geological studies. A low velocity anomaly zone is also detected in Kebumen, where it may be related to the extensional oceanic basin toward the land.
Low, Gavin; Owen, Nicola E.; Joubert, Ilse; Patterson, Andrew J.; Graves, Martin J.; Glaser, Kevin J.; Alexander, Graeme J.M.; Lomas, David J.
2015-01-01
PURPOSE To evaluate the reliability of MRE using a spin-echo echo-planar imaging (SE-EPI) renal MRE technique in healthy volunteers MATERIALS AND METHODS Institutional review board approved prospective study in which all participants provided written informed consent. Sixteen healthy volunteers comprising seven males and nine females with a median age of 35 years (age range: 23 to 59 years) were included. Coronal 90-Hz and 60-Hz MRE acquisitions were performed twice within a 30-minute interval between examinations. Renal MRE reliability was assessed by i) test-retest repeatability, and ii) inter-rater agreement between two independent readers. The MRE-measured averaged renal stiffness values were evaluated using: intraclass correlation coefficient (ICC), Bland-Altman and the within-subject coefficient of variation (COV). RESULTS For test-retest repeatability, Bland-Altman showed a mean stiffness difference between examinations of 0.07 kPa (95% limits of agreement: −1.41, 1.54) at 90-Hz and 0.01 kPa (95% limits of agreement: −0.51, 0.53) at 60-Hz. Coefficient of repeatability was 1.47 kPa and 0.52 kPa at 90-Hz and 60-Hz, respectively. The within-subject COV was 13.6% and 7.7% at 90-Hz and 60-Hz, respectively. ICC values were 0.922 and 0.907 for test-retest repeatability and 0.998 and 0.989 for inter-rater agreement, respectively (p < 0.001). CONCLUSION SE-EPI renal MRE is a reliable technique PMID:25537823
NASA Astrophysics Data System (ADS)
Wang, Jin; Ma, Jianyong; Zhou, Changhe
2014-11-01
A 3×3 high divergent 2D-grating with period of 3.842μm at wavelength of 850nm under normal incidence is designed and fabricated in this paper. This high divergent 2D-grating is designed by the vector theory. The Rigorous Coupled Wave Analysis (RCWA) in association with the simulated annealing (SA) is adopted to calculate and optimize this 2D-grating.The properties of this grating are also investigated by the RCWA. The diffraction angles are more than 10 degrees in the whole wavelength band, which are bigger than the traditional 2D-grating. In addition, the small period of grating increases the difficulties of fabrication. So we fabricate the 2D-gratings by direct laser writing (DLW) instead of traditional manufacturing method. Then the method of ICP etching is used to obtain the high divergent 2D-grating.
Internal Photoemission Spectroscopy of 2-D Materials
NASA Astrophysics Data System (ADS)
Nguyen, Nhan; Li, Mingda; Vishwanath, Suresh; Yan, Rusen; Xiao, Shudong; Xing, Huili; Cheng, Guangjun; Hight Walker, Angela; Zhang, Qin
Recent research has shown the great benefits of using 2-D materials in the tunnel field-effect transistor (TFET), which is considered a promising candidate for the beyond-CMOS technology. The on-state current of TFET can be enhanced by engineering the band alignment of different 2D-2D or 2D-3D heterostructures. Here we present the internal photoemission spectroscopy (IPE) approach to determine the band alignments of various 2-D materials, in particular SnSe2 and WSe2, which have been proposed for new TFET designs. The metal-oxide-2-D semiconductor test structures are fabricated and characterized by IPE, where the band offsets from the 2-D semiconductor to the oxide conduction band minimum are determined by the threshold of the cube root of IPE yields as a function of photon energy. In particular, we find that SnSe2 has a larger electron affinity than most semiconductors and can be combined with other semiconductors to form near broken-gap heterojunctions with low barrier heights which can produce a higher on-state current. The details of data analysis of IPE and the results from Raman spectroscopy and spectroscopic ellipsometry measurements will also be presented and discussed.
QUENCH2D. Two-Dimensional IHCP Code
Osman, A.; Beck, J.V.
1995-01-01
QUENCH2D* is developed for the solution of general, non-linear, two-dimensional inverse heat transfer problems. This program provides estimates for the surface heat flux distribution and/or heat transfer coefficient as a function of time and space by using transient temperature measurements at appropriate interior points inside the quenched body. Two-dimensional planar and axisymmetric geometries such as turnbine disks and blades, clutch packs, and many other problems can be analyzed using QUENCH2D*.
A comparison of solute-transport solution techniques based on inverse modelling results
Mehl, S.; Hill, M.C.
2000-01-01
Five common numerical techniques (finite difference, predictor-corrector, total-variation-diminishing, method-of-characteristics, and modified-method-of-characteristics) were tested using simulations of a controlled conservative tracer-test experiment through a heterogeneous, two-dimensional sand tank. The experimental facility was constructed using randomly distributed homogeneous blocks of five sand types. This experimental model provides an outstanding opportunity to compare the solution techniques because of the heterogeneous hydraulic conductivity distribution of known structure, and the availability of detailed measurements with which to compare simulated concentrations. The present work uses this opportunity to investigate how three common types of results-simulated breakthrough curves, sensitivity analysis, and calibrated parameter values-change in this heterogeneous situation, given the different methods of simulating solute transport. The results show that simulated peak concentrations, even at very fine grid spacings, varied because of different amounts of numerical dispersion. Sensitivity analysis results were robust in that they were independent of the solution technique. They revealed extreme correlation between hydraulic conductivity and porosity, and that the breakthrough curve data did not provide enough information about the dispersivities to estimate individual values for the five sands. However, estimated hydraulic conductivity values are significantly influenced by both the large possible variations in model dispersion and the amount of numerical dispersion present in the solution technique.Five common numerical techniques (finite difference, predictor-corrector, total-variation-diminishing, method-of-characteristics, and modified-method-of-characteristics) were tested using simulations of a controlled conservative tracer-test experiment through a heterogeneous, two-dimensional sand tank. The experimental facility was constructed using randomly
Stability results for the parameter identification inverse problem in cardiac electrophysiology
NASA Astrophysics Data System (ADS)
Lassoued, Jamila; Mahjoub, Moncef; Zemzemi, Néjib
2016-11-01
In this paper we prove a stability estimate of the parameter identification problem in cardiac electrophysiology modeling. We use the monodomain model which is a reaction diffusion parabolic equation where the reaction term is obtained by solving an ordinary differential equation (ODE). We are interested in proving the stability of the identification of the parameter {τ }{in}, which is the parameter that multiplies the cubic term in the reaction term. The proof of the result is based on a new Carleman-type estimate for both partial differential equation (PDE) and ODE problems. As a consequence of the stability result we prove the uniqueness of the parameter {τ }{in} giving some observations of both state variables at a given time t 0 in the whole domain and in the PDE variable in a non empty open subset w 0 of the domain.
Inverse Comptonization in a Two Component Advective Flow: Results of a Monte Carlo simulation
Ghosh, Himadri; Chakrabarti, S. K.; Laurent, Philippe
2008-10-08
We compute the resultant spectrum due to multiple scattering of soft photons emitted from a Keplerian disk by thermal electrons inside a torus axisymmetrically placed around a black hole. In a two component advective flow model, the post-shock region is similar to a thick accretion disk and the pre-shock sub-keplerian flow is highly optically thin. As a preliminary run of the Monte Carlo simulation of the system, we assume the CENBOL to be a small (2-14r{sub g}) thick accretion disk without a cusp to allow bulk motion of the flow. Bulk Motion Comptonization (BMC) has also been added. We show that the spectral behaviour is very similar to what is predicted in Chakrabarti and Titarchuk (1995)
Brittle damage models in DYNA2D
Faux, D.R.
1997-09-01
DYNA2D is an explicit Lagrangian finite element code used to model dynamic events where stress wave interactions influence the overall response of the system. DYNA2D is often used to model penetration problems involving ductile-to-ductile impacts; however, with the advent of the use of ceramics in the armor-anti-armor community and the need to model damage to laser optics components, good brittle damage models are now needed in DYNA2D. This report will detail the implementation of four brittle damage models in DYNA2D, three scalar damage models and one tensor damage model. These new brittle damage models are then used to predict experimental results from three distinctly different glass damage problems.
2D Spinodal Decomposition in Forced Turbulence
NASA Astrophysics Data System (ADS)
Fan, Xiang; Diamond, Patrick; Chacon, Luis; Li, Hui
2015-11-01
Spinodal decomposition is a second order phase transition for binary fluid mixture, from one thermodynamic phase to form two coexisting phases. The governing equation for this coarsening process below critical temperature, Cahn-Hilliard Equation, is very similar to 2D MHD Equation, especially the conserved quantities have a close correspondence between each other, so theories for MHD turbulence are used to study spinodal decomposition in forced turbulence. Domain size is increased with time along with the inverse cascade, and the length scale can be arrested by a forced turbulence with direct cascade. The two competing mechanisms lead to a stabilized domain size length scale, which can be characterized by Hinze Scale. The 2D spinodal decomposition in forced turbulence is studied by both theory and simulation with ``pixie2d.'' This work focuses on the relation between Hinze scale and spectra and cascades. Similarities and differences between spinodal decomposition and MHD are investigated. Also some transport properties are studied following MHD theories. This work is supported by the Department of Energy under Award Number DE-FG02-04ER54738.
Baiz, Carlos R.; Schach, Denise; Tokmakoff, Andrei
2014-01-01
We describe a microscope for measuring two-dimensional infrared (2D IR) spectra of heterogeneous samples with μm-scale spatial resolution, sub-picosecond time resolution, and the molecular structure information of 2D IR, enabling the measurement of vibrational dynamics through correlations in frequency, time, and space. The setup is based on a fully collinear “one beam” geometry in which all pulses propagate along the same optics. Polarization, chopping, and phase cycling are used to isolate the 2D IR signals of interest. In addition, we demonstrate the use of vibrational lifetime as a contrast agent for imaging microscopic variations in molecular environments. PMID:25089490
2004-08-01
AnisWave2D is a 2D finite-difference code for a simulating seismic wave propagation in fully anisotropic materials. The code is implemented to run in parallel over multiple processors and is fully portable. A mesh refinement algorithm has been utilized to allow the grid-spacing to be tailored to the velocity model, avoiding the over-sampling of high-velocity materials that usually occurs in fixed-grid schemes.
NASA Astrophysics Data System (ADS)
Portal, Angélie; Fargier, Yannick; Lénat, Jean-François; Labazuy, Philippe
2016-04-01
The electrical resistivity tomography (ERT) method, initially developed for environmental and engineering exploration, is now commonly used for geological structures imaging. Such structures can present complex characteristics that conventional 2D inversion processes cannot perfectly integrate. Here we present a new 3D inversion algorithm named EResI, firstly developed for levee investigation, and presently applied to the study of a complex lava dome (the Puy de Dôme volcano, France). EResI algorithm is based on a conventional regularized Gauss-Newton inversion scheme and a 3D non-structured discretization of the model (double grid method based on tetrahedrons). This discretization allows to accurately model the topography of investigated structure (without a mesh deformation procedure) and also permits a precise location of the electrodes. Moreover, we demonstrate that a complete 3D unstructured discretization limits the number of inversion cells and is better adapted to the resolution capacity of tomography than a structured discretization. This study shows that a 3D inversion with a non-structured parametrization has some advantages compared to classical 2D inversions. The first advantage comes from the fact that a 2D inversion leads to artefacts due to 3D effects (3D topography, 3D internal resistivity). The second advantage comes from the fact that the capacity to experimentally align electrodes along an axis (for 2D surveys) depends on the constrains on the field (topography...). In this case, a 2D assumption induced by 2.5D inversion software prevents its capacity to model electrodes outside this axis leading to artefacts in the inversion result. The last limitation comes from the use of mesh deformation techniques used to accurately model the topography in 2D softwares. This technique used for structured discretization (Res2dinv) is prohibed for strong topography (>60 %) and leads to a small computational errors. A wide geophysical survey was carried out
Gil, Bomi; Hwang, Eo-Jin; Lee, Song; Jang, Jinhee; Jung, So-Lyung; Ahn, Kook-Jin; Kim, Bum-soo
2016-01-01
Introduction To compare the diagnostic accuracy of contrast-enhanced 3D(dimensional) T1-weighted sampling perfection with application-optimized contrasts by using different flip angle evolutions (T1-SPACE), 2D fluid attenuated inversion recovery (FLAIR) images and 2D contrast-enhanced T1-weighted image in detection of leptomeningeal metastasis except for invasive procedures such as a CSF tapping. Materials and Methods Three groups of patients were included retrospectively for 9 months (from 2013-04-01 to 2013-12-31). Group 1 patients with positive malignant cells in CSF cytology (n = 22); group 2, stroke patients with steno-occlusion in ICA or MCA (n = 16); and group 3, patients with negative results on MRI, whose symptom were dizziness or headache (n = 25). A total of 63 sets of MR images are separately collected and randomly arranged: (1) CE 3D T1-SPACE; (2) 2D FLAIR; and (3) CE T1-GRE using a 3-Tesla MR system. A faculty neuroradiologist with 8-year-experience and another 2nd grade trainee in radiology reviewed each MR image- blinded by the results of CSF cytology and coded their observations as positives or negatives of leptomeningeal metastasis. The CSF cytology result was considered as a gold standard. Sensitivity and specificity of each MR images were calculated. Diagnostic accuracy was compared using a McNemar’s test. A Cohen's kappa analysis was performed to assess inter-observer agreements. Results Diagnostic accuracy was not different between 3D T1-SPACE and CSF cytology by both raters. However, the accuracy test of 2D FLAIR and 2D contrast-enhanced T1-weighted GRE was inconsistent by the two raters. The Kappa statistic results were 0.657 (3D T1-SPACE), 0.420 (2D FLAIR), and 0.160 (2D contrast-enhanced T1-weighted GRE). The 3D T1-SPACE images showed the highest inter-observer agreements between the raters. Conclusions Compared to 2D FLAIR and 2D contrast-enhanced T1-weighted GRE, contrast-enhanced 3D T1 SPACE showed a better detection rate of
Ramig, Keith; Subramaniam, Gopal; Karimi, Sasan; Szalda, David J; Ko, Allen; Lam, Aaron; Li, Jeffrey; Coaderaj, Ani; Cavdar, Leyla; Bogdan, Lukasz; Kwon, Kitae; Greer, Edyta M
2016-04-15
A series of 2,4-disubstituted 1H-1-benzazepines, 2a-d, 4, and 6, were studied, varying both the substituents at C2 and C4 and at the nitrogen atom. The conformational inversion (ring-flip) and nitrogen-atom inversion (N-inversion) energetics were studied by variable-temperature NMR spectroscopy and computations. The steric bulk of the nitrogen-atom substituent was found to affect both the conformation of the azepine ring and the geometry around the nitrogen atom. Also affected were the Gibbs free energy barriers for the ring-flip and the N-inversion. When the nitrogen-atom substituent was alkyl, as in 2a-c, the geometry of the nitrogen atom was nearly planar and the azepine ring was highly puckered; the result was a relatively high-energy barrier to ring-flip and a low barrier to N-inversion. Conversely, when the nitrogen-atom substituent was a hydrogen atom, as in 2d, 4, and 6, the nitrogen atom was significantly pyramidalized and the azepine ring was less puckered; the result here was a relatively high energy barrier to N-inversion and a low barrier to ring-flip. In these N-unsubstituted compounds, it was found computationally that the lowest-energy stereodynamic process was ring-flip coupled with N-inversion, as N-inversion alone had a much higher energy barrier.
Tønning, Erik; Polders, Daniel; Callaghan, Paul T; Engelsen, Søren B
2007-09-01
This paper demonstrates how the multi-linear PARAFAC model can with advantage be used to decompose 2D diffusion-relaxation correlation NMR spectra prior to 2D-Laplace inversion to the T(2)-D domain. The decomposition is advantageous for better interpretation of the complex correlation maps as well as for the quantification of extracted T(2)-D components. To demonstrate the new method seventeen mixtures of wheat flour, starch, gluten, oil and water were prepared and measured with a 300 MHz nuclear magnetic resonance (NMR) spectrometer using a pulsed gradient stimulated echo (PGSTE) pulse sequence followed by a Carr-Purcell-Meiboom-Gill (CPMG) pulse echo train. By varying the gradient strength, 2D diffusion-relaxation data were recorded for each sample. From these double exponentially decaying relaxation data the PARAFAC algorithm extracted two unique diffusion-relaxation components, explaining 99.8% of the variation in the data set. These two components were subsequently transformed to the T(2)-D domain using 2D-inverse Laplace transformation and quantitatively assigned to the oil and water components of the samples. The oil component was one distinct distribution with peak intensity at D=3 x 10(-12) m(2) s(-1) and T(2)=180 ms. The water component consisted of two broad populations of water molecules with diffusion coefficients and relaxation times centered around correlation pairs: D=10(-9) m(2) s(-1), T(2)=10 ms and D=3 x 10(-13) m(2) s(-1), T(2)=13 ms. Small spurious peaks observed in the inverse Laplace transformation of original complex data were effectively filtered by the PARAFAC decomposition and thus considered artefacts from the complex Laplace transformation. The oil-to-water ratio determined by PARAFAC followed by 2D-Laplace inversion was perfectly correlated with known oil-to-water ratio of the samples. The new method of using PARAFAC prior to the 2D-Laplace inversion proved to have superior potential in analysis of diffusion-relaxation spectra, as it
NASA Astrophysics Data System (ADS)
Tønning, Erik; Polders, Daniel; Callaghan, Paul T.; Engelsen, Søren B.
2007-09-01
This paper demonstrates how the multi-linear PARAFAC model can with advantage be used to decompose 2D diffusion-relaxation correlation NMR spectra prior to 2D-Laplace inversion to the T2- D domain. The decomposition is advantageous for better interpretation of the complex correlation maps as well as for the quantification of extracted T2- D components. To demonstrate the new method seventeen mixtures of wheat flour, starch, gluten, oil and water were prepared and measured with a 300 MHz nuclear magnetic resonance (NMR) spectrometer using a pulsed gradient stimulated echo (PGSTE) pulse sequence followed by a Carr-Purcell-Meiboom-Gill (CPMG) pulse echo train. By varying the gradient strength, 2D diffusion-relaxation data were recorded for each sample. From these double exponentially decaying relaxation data the PARAFAC algorithm extracted two unique diffusion-relaxation components, explaining 99.8% of the variation in the data set. These two components were subsequently transformed to the T2- D domain using 2D-inverse Laplace transformation and quantitatively assigned to the oil and water components of the samples. The oil component was one distinct distribution with peak intensity at D = 3 × 10 -12 m 2 s -1 and T2 = 180 ms. The water component consisted of two broad populations of water molecules with diffusion coefficients and relaxation times centered around correlation pairs: D = 10 -9 m 2 s -1, T2 = 10 ms and D = 3 × 10 -13 m 2 s -1, T2 = 13 ms. Small spurious peaks observed in the inverse Laplace transformation of original complex data were effectively filtered by the PARAFAC decomposition and thus considered artefacts from the complex Laplace transformation. The oil-to-water ratio determined by PARAFAC followed by 2D-Laplace inversion was perfectly correlated with known oil-to-water ratio of the samples. The new method of using PARAFAC prior to the 2D-Laplace inversion proved to have superior potential in analysis of diffusion-relaxation spectra, as it
Two-dimensional inverse opal hydrogel for pH sensing.
Xue, Fei; Meng, Zihui; Qi, Fenglian; Xue, Min; Wang, Fengyan; Chen, Wei; Yan, Zequn
2014-12-01
A novel hydrogel film with a highly ordered macropore monolayer on its surface was prepared by templated photo-polymerization of hydrogel monomers on a two-dimensional (2D) polystyrene colloidal array. The 2D inverse opal hydrogel has prominent advantages over traditional three-dimensional (3D) inverse opal hydrogels. First, the formation of the 2D array template through a self-assembly method is considerably faster and simpler. Second, the stable ordering structure of the 2D array template makes it easier to introduce the polymerization solution into the template. Third, a simple measurement, a Debye diffraction ring, is utilized to characterize the neighboring pore spacing of the 2D inverse opal hydrogel. Acrylic acid was copolymerized into the hydrogel; thus, the hydrogel responded to pH through volume change, which resulted from the formation of the Donnan potential. The 2D inverse opal hydrogel showed that the neighboring pore spacing increased by about 150 nm and diffracted color red-shifted from blue to red as the pH increased from pH 2 to 7. In addition, the pH response kinetics and ionic strength effect of this 2D mesoporous polymer film were also investigated. PMID:25292208
Two-dimensional inverse opal hydrogel for pH sensing.
Xue, Fei; Meng, Zihui; Qi, Fenglian; Xue, Min; Wang, Fengyan; Chen, Wei; Yan, Zequn
2014-12-01
A novel hydrogel film with a highly ordered macropore monolayer on its surface was prepared by templated photo-polymerization of hydrogel monomers on a two-dimensional (2D) polystyrene colloidal array. The 2D inverse opal hydrogel has prominent advantages over traditional three-dimensional (3D) inverse opal hydrogels. First, the formation of the 2D array template through a self-assembly method is considerably faster and simpler. Second, the stable ordering structure of the 2D array template makes it easier to introduce the polymerization solution into the template. Third, a simple measurement, a Debye diffraction ring, is utilized to characterize the neighboring pore spacing of the 2D inverse opal hydrogel. Acrylic acid was copolymerized into the hydrogel; thus, the hydrogel responded to pH through volume change, which resulted from the formation of the Donnan potential. The 2D inverse opal hydrogel showed that the neighboring pore spacing increased by about 150 nm and diffracted color red-shifted from blue to red as the pH increased from pH 2 to 7. In addition, the pH response kinetics and ionic strength effect of this 2D mesoporous polymer film were also investigated.
Commer, Michael; Helwig, Stefan, L.; Hordt, Andreas; Scholl,Carsten; Tezkan, Bulent
2006-06-14
Three long-offset transient electromagnetic (LOTEM) surveyswerecarried out at the active volcano Merapi in Central Java (Indonesia)during the years 1998, 2000, and 2001. The measurements focused on thegeneral resistivity structure of the volcanic edifice at depths of 0.5-2km and the further investigation of a southside anomaly. The measurementswere insufficient for a full 3D inversion scheme, which could enable theimaging of finely discretized resistivity distributions. Therefore, astable, damped least-squares joint-inversion approach is used to optimize3D models with a limited number of parameters. The mode ls feature therealistic simulation of topography, a layered background structure, andadditional coarse 3D blocks representing conductivity anomalies.Twenty-eight LOTEM transients, comprising both horizontal and verticalcomponents of the magnetic induction time derivative, were analyzed. Inview of the few unknowns, we were able to achieve reasonable data fits.The inversion results indicate an upwelling conductor below the summit,suggesting hydrothermal activity in the central volcanic complex. Ashallow conductor due to a magma-filled chamber, at depths down to 1 kmbelow the summit, suggested by earlier seismic studies, is not indicatedby the inversion results. In conjunction with an anomalous-density model,derived from arecent gravity study, our inversion results provideinformation about the southern geological structure resulting from amajor sector collapse during the Middle Merapi period. The density modelallows to assess a porosity range andthus an estimated vertical salinityprofile to explain the high conductivities on a larger scale, extendingbeyond the foothills of Merapi.
DYNA2D96. Explicit 2-D Hydrodynamic FEM Program
Whirley, R.G.
1992-04-01
DYNA2D is a vectorized, explicit, two-dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic/isotropic elastic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, rubber, high explosive burn, isotropic elastic-plastic, temperature-dependent elastic-plastic. The isotropic and temperature-dependent elastic-plastic models determine only the deviatoric stresses. Pressure is determined by one of 9 equations of state including linear polynomial, JWL high explosive, Sack Tuesday high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, and tabulated.
NASA Astrophysics Data System (ADS)
Kiyan, Duygu; Jones, Alan G.; Vozar, Jan
2014-03-01
In this paper, we use synthetic data sets from a profile to demonstrate the importance of aligning the 3-D mesh and data coordinate system with the dominant geo-electrical strike direction in 3-D inverse modelling. The resistivity model investigated consists of a regional, elongated 2-D conductive structure at 45° to the profile. We compare the results of full impedance tensor inversion with the results from inversion of only off-diagonal components of the magnetotelluric impedance tensor. The 3-D inversion result obtained with the complete tensor elements yields the subsurface model closest to the original model, whereas the result of inverting only off-diagonal components is the poor imaging of the continuity of the conductive 2-D body. However, the conductor can be correctly recovered using only the off-diagonal components if the model mesh and the data are aligned with quasi-2-D geo-electrical strike.
Radiative heat transfer in 2D Dirac materials.
Rodriguez-López, Pablo; Tse, Wang-Kong; Dalvit, Diego A R
2015-06-01
We compute the radiative heat transfer between two sheets of 2D Dirac materials, including topological Chern insulators and graphene, within the framework of the local approximation for the optical response of these materials. In this approximation, which neglects spatial dispersion, we derive both numerically and analytically the short-distance asymptotic of the near-field heat transfer in these systems, and show that it scales as the inverse of the distance between the two sheets. Finally, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials. PMID:25965703
Radiative heat transfer in 2D Dirac materials
Rodriguez-López, Pablo; Tse, Wang -Kong; Dalvit, Diego A. R.
2015-05-12
We compute the radiative heat transfer between two sheets of 2D Dirac materials, including topological Chern insulators and graphene, within the framework of the local approximation for the optical response of these materials. In this approximation, which neglects spatial dispersion, we derive both numerically and analytically the short-distance asymptotic of the near-field heat transfer in these systems, and show that it scales as the inverse of the distance between the two sheets. In conclusion, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials.
2001-01-31
This software reduces the data from two-dimensional kSA MOS program, k-Space Associates, Ann Arbor, MI. Initial MOS data is recorded without headers in 38 columns, with one row of data per acquisition per lase beam tracked. The final MOSS 2d data file is reduced, graphed, and saved in a tab-delimited column format with headers that can be plotted in any graphing software.
Lehner, Manfred; Götz, Gabriel; Proff, Julia; Schaft, Niels; Dörrie, Jan; Full, Florian; Ensser, Armin; Muller, Yves A; Cerwenka, Adelheid; Abken, Hinrich; Parolini, Ornella; Ambros, Peter F; Kovar, Heinrich; Holter, Wolfgang
2012-01-01
We explored the possibility to target Ewing's sarcoma family of tumors (ESFT) by redirecting T cells. To this aim, we considered NKG2D-ligands (NKG2D-Ls) as possible target antigens. Detailed analysis of the expression of MICA, MICB, ULBP-1, -2, and -3 in fourteen ESFT cell lines revealed consistent expression of at least one NKG2D-L. Thus, for redirecting T cells, we fused a CD3ζ/CD28-derived signaling domain to the ectodomain of NKG2D, however, opposite transmembrane orientation of this signaling domain and NKG2D required inverse orientation fusion of either of them. We hypothesized that the particularly located C-terminus of the NKG2D ectodomain should allow reengineering of the membrane anchoring from a native N-terminal to an artificial C-terminal linkage. Indeed, the resulting chimeric NKG2D receptor (chNKG2D) was functional and efficiently mediated ESFT cell death triggered by activated T cells. Notably, ESFT cells with even low NKG2D-L expression were killed by CD8(pos) and also CD4(pos) cells. Both, mRNA transfection and lentiviral transduction resulted in high level surface expression of chNKG2D. However, upon target-cell recognition receptor surface levels were maintained by tranfected RNA only during the first couple of hours after transfection. Later, target-cell contact resulted in strong and irreversible receptor down-modulation, whereas lentivirally mediated expression of chNKG2D remained constant under these conditions. Together, our study defines NKG2D-Ls as targets for a CAR-mediated T cell based immunotherapy of ESFT. A comparison of two different methods of gene transfer reveals strong differences in the susceptibility to ligand-induced receptor down-modulation with possible implications for the applicability of RNA transfection. PMID:22355347
NASA Technical Reports Server (NTRS)
Moghaddam, Mahta; Pierce, Leland; Tabatabaeenejad, Alireza; Rodriguez, Ernesto
2005-01-01
Knowledge of subsurface characteristics such as permittivity variations and layering structure could provide a breakthrough in many terrestrial and planetary science disciplines. For Earth science, knowledge of subsurface and subcanopy soil moisture layers can enable the estimation of vertical flow in the soil column linking surface hydrologic processes with that in the subsurface. For planetary science, determining the existence of subsurface water and ice is regarded as one of the most critical information needs for the study of the origins of the solar system. The subsurface in general can be described as several near-parallel layers with rough interfaces. Each homogenous rough layer can be defined by its average thickness, permittivity, and rms interface roughness assuming a known surface spectral distribution. As the number and depth of layers increase, the number of measurements needed to invert for the layer unknowns also increases, and deeper penetration capability would be required. To nondestructively calculate the characteristics of the rough layers, a multifrequency polarimetric radar backscattering approach can be used. One such system is that we have developed for data prototyping of the Microwave Observatory of Subcanopy and Subsurface (MOSS) mission concept. A tower-mounted radar makes backscattering measurements at VHF, UHF, and L-band frequencies. The radar is a pulsed CW system, which uses the same wideband antenna to transmit and receive the signals at all three frequencies. To focus the beam at various incidence angles within the beamwidth of the antenna, the tower is moved vertically and measurements made at each position. The signals are coherently summed to achieve focusing and image formation in the subsurface. This requires an estimate of wave velocity profiles. To solve the inverse scattering problem for subsurface velocity profile simultaneously with radar focusing, we use an iterative technique based on a forward numerical solution of
NASA Astrophysics Data System (ADS)
Rendón, A.; Wirth, V.; Salazar, J. F.; Palacio, C. A.; Brötz, B.
2014-12-01
Urban valleys can experience serious air pollution problems of concern for public health. The venting of pollution out of an urban valley is limited by the topography and can be further restricted by low-level temperature inversions and/or local circulations such as those induced by the Urban Heat Island (UHI) effect. The combined effects of a temperature inversion and a UHI on the dynamics of the atmospheric boundary layer and the associated mechanisms of air pollution transport in urban valleys were studied through idealized simulations performed with the EULAG model. Three different aspects were considered: the expansion of the urban area, variations in surface heating owing to topographic shading, and variations of the topography. The results show that different mechanisms of air pollution transport may arise in urban valleys as a result of the interplay between the temperature inversion, the slope flows, and the UHI. Three types of interrelated mechanisms of air pollution transport were identified. Type A describes the transport of pollutants by the slope winds, which can reduce pollution in the lower levels or reinforce the trapping of pollutants below the inversion layer depending on the UHI effect on weakening or reversing the upslope winds. Type B describes closed slope-flow circulations that are likely to occur below an inversion layer near the base of the sidewalls of valleys where an urban area is concentrated on the valley floor. These circulations can develop when upslope winds are detrained toward the center due to the inversion layer, or when the UHI forces downslope winds linked to ascending flows that are also restricted by the inversion layer. Pollutants can remain trapped within these circulation cells that have been termed smog traps. Type C describes a low-level UHI-induced circulation that tends to concentrate pollutants in the valley center and may cause the development of elevated polluted layers below the inversion layer. The persistence
2-D or not 2-D, that is the question: A Northern California test
Mayeda, K; Malagnini, L; Phillips, W S; Walter, W R; Dreger, D
2005-06-06
Reliable estimates of the seismic source spectrum are necessary for accurate magnitude, yield, and energy estimation. In particular, how seismic radiated energy scales with increasing earthquake size has been the focus of recent debate within the community and has direct implications on earthquake source physics studies as well as hazard mitigation. The 1-D coda methodology of Mayeda et al. has provided the lowest variance estimate of the source spectrum when compared against traditional approaches that use direct S-waves, thus making it ideal for networks that have sparse station distribution. The 1-D coda methodology has been mostly confined to regions of approximately uniform complexity. For larger, more geophysically complicated regions, 2-D path corrections may be required. The complicated tectonics of the northern California region coupled with high quality broadband seismic data provides for an ideal ''apples-to-apples'' test of 1-D and 2-D path assumptions on direct waves and their coda. Using the same station and event distribution, we compared 1-D and 2-D path corrections and observed the following results: (1) 1-D coda results reduced the amplitude variance relative to direct S-waves by roughly a factor of 8 (800%); (2) Applying a 2-D correction to the coda resulted in up to 40% variance reduction from the 1-D coda results; (3) 2-D direct S-wave results, though better than 1-D direct waves, were significantly worse than the 1-D coda. We found that coda-based moment-rate source spectra derived from the 2-D approach were essentially identical to those from the 1-D approach for frequencies less than {approx}0.7-Hz, however for the high frequencies (0.7{le} f {le} 8.0-Hz), the 2-D approach resulted in inter-station scatter that was generally 10-30% smaller. For complex regions where data are plentiful, a 2-D approach can significantly improve upon the simple 1-D assumption. In regions where only 1-D coda correction is available it is still preferable over 2
WFR-2D: an analytical model for PWAS-generated 2D ultrasonic guided wave propagation
NASA Astrophysics Data System (ADS)
Shen, Yanfeng; Giurgiutiu, Victor
2014-03-01
This paper presents WaveFormRevealer 2-D (WFR-2D), an analytical predictive tool for the simulation of 2-D ultrasonic guided wave propagation and interaction with damage. The design of structural health monitoring (SHM) systems and self-aware smart structures requires the exploration of a wide range of parameters to achieve best detection and quantification of certain types of damage. Such need for parameter exploration on sensor dimension, location, guided wave characteristics (mode type, frequency, wavelength, etc.) can be best satisfied with analytical models which are fast and efficient. The analytical model was constructed based on the exact 2-D Lamb wave solution using Bessel and Hankel functions. Damage effects were inserted in the model by considering the damage as a secondary wave source with complex-valued directivity scattering coefficients containing both amplitude and phase information from wave-damage interaction. The analytical procedure was coded with MATLAB, and a predictive simulation tool called WaveFormRevealer 2-D was developed. The wave-damage interaction coefficients (WDICs) were extracted from harmonic analysis of local finite element model (FEM) with artificial non-reflective boundaries (NRB). The WFR-2D analytical simulation results were compared and verified with full scale multiphysics finite element models and experiments with scanning laser vibrometer. First, Lamb wave propagation in a pristine aluminum plate was simulated with WFR-2D, compared with finite element results, and verified by experiments. Then, an inhomogeneity was machined into the plate to represent damage. Analytical modeling was carried out, and verified by finite element simulation and experiments. This paper finishes with conclusions and suggestions for future work.
NASA Astrophysics Data System (ADS)
Hu, Jinbing; Liang, Binming; Chen, Jiabi; Cai, Xiaoshu; Jiang, Qiang; Zhuang, Songlin
2016-07-01
The effect of surface termination on the inverse Goos–Hänchen (GH) shift of two-dimensional (2D) negatively refractive photonic crystals (NRPhCs) containing air holes arranged in a hexagonal lattice in a dielectric background is investigated for transverse magnetic (TM) polarization. Results show that the magnitude of the inverse GH shift of 2D-NRPhCs strongly depends on surface termination even for an incident beam with a fixed frequency and incidence angle. Calculation of dispersion of surface mode as a function of termination reveals that large inverse GH shift of 2D-NRPhCs results from the excitation of backward surface mode. In addition, the coupling coefficient of the incident field into the field of surface mode and energy flux around the interface are studied and demonstrate the above conclusion. This paper will provide technical information regarding the combination of various functional photonic elements in the design of integrated optical circuits.
2D Quantum Mechanical Study of Nanoscale MOSFETs
NASA Technical Reports Server (NTRS)
Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, B.; Kwak, Dochan (Technical Monitor)
2000-01-01
With the onset of quantum confinement in the inversion layer in nanoscale MOSFETs, behavior of the resonant level inevitably determines all device characteristics. While most classical device simulators take quantization into account in some simplified manner, the important details of electrostatics are missing. Our work addresses this shortcoming and provides: (a) a framework to quantitatively explore device physics issues such as the source-drain and gate leakage currents, DIBL, and threshold voltage shift due to quantization, and b) a means of benchmarking quantum corrections to semiclassical models (such as density-gradient and quantum-corrected MEDICI). We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions and oxide tunneling are treated on an equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. We present the results of our simulations of MIT 25, 50 and 90 nm "well-tempered" MOSFETs and compare them to those of classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. Surprisingly, the self-consistent potential profile shows lower injection barrier in the channel in quantum case. These results are qualitatively consistent with ID Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and subthreshold current has been studied. The shorter gate length device has an order of magnitude smaller current at zero gate bias than the longer gate length device without a significant trade-off in on-current. This should be a device design consideration.
Design and implementation of a 2-D endoscopic optical fiber scanner
NASA Astrophysics Data System (ADS)
Liu, Zhihai; Fu, Ling; Gao, Fei; Zhang, Xiongbo
2008-12-01
We have designed a small type of endoscopic 2D fiber scanner probe to incorporate OCT with endoscopy imaging. The new probe consists with two piezoelectric ceramics plated with electrode, a conductive thin-film with non-inverse piezoelectric effect and a piece of nude fiber with coating layers removed. To accomplish the scanning, the only thing need to be done is to drive the two piezoelectric ceramic sheets which provides simpler structure and at the same time minimizes the probe effectively. Here we have obtained some preliminary results and verified the feasibility of the program.
Partial trisomy 22 (q11.2-q13.1) as a result of duplication and pericentric inversion.
Prasher, V P; Roberts, E; Norman, A; Butler, A C; Krishnan, V H; McMullan, D J
1995-01-01
A case of a 27 year old male with a duplication of part of the long arm of chromosome 22 (22q11.2-q13.1) together with a pericentric inversion of the same chromosome is reported. Particular phenotypic features of note include absence of speech, persistent self-injury, lack of daily living skills, colobomata, and very poor vision. Similarities between this case and other case reports of duplications of the long arm of chromosome 22 are discussed. Images PMID:7643363
2D photonic-crystal optomechanical nanoresonator.
Makles, K; Antoni, T; Kuhn, A G; Deléglise, S; Briant, T; Cohadon, P-F; Braive, R; Beaudoin, G; Pinard, L; Michel, C; Dolique, V; Flaminio, R; Cagnoli, G; Robert-Philip, I; Heidmann, A
2015-01-15
We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8% over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265-nm thick membrane, is used to form a compact microcavity involving the suspended nanomembrane as an end mirror. The resulting cavity has a waist size smaller than 10 μm and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane. PMID:25679837
Georgi, Howard; Kats, Yevgeny
2008-09-26
We discuss what can be learned about unparticle physics by studying simple quantum field theories in one space and one time dimension. We argue that the exactly soluble 2D theory of a massless fermion coupled to a massive vector boson, the Sommerfield model, is an interesting analog of a Banks-Zaks model, approaching a free theory at high energies and a scale-invariant theory with nontrivial anomalous dimensions at low energies. We construct a toy standard model coupling to the fermions in the Sommerfield model and study how the transition from unparticle behavior at low energies to free particle behavior at high energies manifests itself in interactions with the toy standard model particles.
2D Quantum Transport Modeling in Nanoscale MOSFETs
NASA Technical Reports Server (NTRS)
Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, Bryan
2001-01-01
With the onset of quantum confinement in the inversion layer in nanoscale MOSFETs, behavior of the resonant level inevitably determines all device characteristics. While most classical device simulators take quantization into account in some simplified manner, the important details of electrostatics are missing. Our work addresses this shortcoming and provides: (a) a framework to quantitatively explore device physics issues such as the source-drain and gate leakage currents, DIBL, and threshold voltage shift due to quantization, and b) a means of benchmarking quantum corrections to semiclassical models (such as density- gradient and quantum-corrected MEDICI). We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions, oxide tunneling and phase-breaking scattering are treated on equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. Quantum simulations are focused on MIT 25, 50 and 90 nm "well- tempered" MOSFETs and compared to classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. These results are quantitatively consistent with I D Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and sub-threshold current has been studied. The shorter gate length device has an order of magnitude smaller current at zero gate bias than the longer gate length device without a significant trade-off in on-current. This should be a device design consideration.
NASA Astrophysics Data System (ADS)
Tietze, Kristina; Ritter, Oliver
2013-10-01
3-D inversion techniques have become a widely used tool in magnetotelluric (MT) data interpretation. However, with real data sets, many of the controlling factors for the outcome of 3-D inversion are little explored, such as alignment of the coordinate system, handling and influence of data errors and model regularization. Here we present 3-D inversion results of 169 MT sites from the central San Andreas Fault in California. Previous extensive 2-D inversion and 3-D forward modelling of the data set revealed significant along-strike variation of the electrical conductivity structure. 3-D inversion can recover these features but only if the inversion parameters are tuned in accordance with the particularities of the data set. Based on synthetic 3-D data we explore the model space and test the impacts of a wide range of inversion settings. The tests showed that the recovery of a pronounced regional 2-D structure in inversion of the complete impedance tensor depends on the coordinate system. As interdependencies between data components are not considered in standard 3-D MT inversion codes, 2-D subsurface structures can vanish if data are not aligned with the regional strike direction. A priori models and data weighting, that is, how strongly individual components of the impedance tensor and/or vertical magnetic field transfer functions dominate the solution, are crucial controls for the outcome of 3-D inversion. If deviations from a prior model are heavily penalized, regularization is prone to result in erroneous and misleading 3-D inversion models, particularly in the presence of strong conductivity contrasts. A `good' overall rms misfit is often meaningless or misleading as a huge range of 3-D inversion results exist, all with similarly `acceptable' misfits but producing significantly differing images of the conductivity structures. Reliable and meaningful 3-D inversion models can only be recovered if data misfit is assessed systematically in the frequency
Qiu, Youzhu; Yang, Jie; Bian, Shizhu; Chen, Guozhu; Yu, Jie
2016-06-01
Peroxisome proliferator-activated receptor gamma (PPARγ), a multiple functional transcription factor, has been reported to have anti-tumor effects through inhibition of cells proliferation. However, its effects on cardiac myxoma (CM) cells and the underlying signaling mechanism is unclear. In the present study, we demonstrated that the level of PPARγ is inversely correlated with that of myocyte enhancer factor 2D (MEF2D), a biomarker of CM. We found that activation of PPARγ inhibit MEF2D expression via upregulation of miR-122, which can target the 3'-UTR of MEF2D and inhibit MEF2D expression, by directly binding to the PPRE in the miR-122 promoter region. Functional experiments further showed that miR-122-dependent downregulation of MEF2D by PPARγ suppress the proliferation of CM cells. These results suggest that PPARγ may exert its antiproliferative effects by negatively regulating the MEF2D in CM cells, which through upregulation of miR-122, and PPARγ/miR-122/MEF2D signaling pathway may be a novel target for treatment of CM. PMID:27109478
NASA Astrophysics Data System (ADS)
Kalscheuer, Thomas; Blake, Sarah; Podgorski, Joel E.; Wagner, Frederic; Green, Alan G.; Maurer, Hansruedi; Jones, Alan G.; Muller, Mark; Ntibinyane, Ongkopotse; Tshoso, Gomotsang
2015-09-01
The Okavango Delta of northern Botswana is one of the world's largest inland deltas or megafans. To obtain information on the character of sediments and basement depths, audiomagnetotelluric (AMT), controlled-source audiomagnetotelluric (CSAMT) and central-loop transient electromagnetic (TEM) data were collected on the largest island within the delta. The data were inverted individually and jointly for 1-D models of electric resistivity. Distortion effects in the AMT and CSAMT data were accounted for by including galvanic distortion tensors as free parameters in the inversions. By employing Marquardt-Levenberg inversion, we found that a 3-layer model comprising a resistive layer overlying sequentially a conductive layer and a deeper resistive layer was sufficient to explain all of the electromagnetic data. However, the top of the basal resistive layer from electromagnetic-only inversions was much shallower than the well-determined basement depth observed in high-quality seismic reflection images and seismic refraction velocity tomograms. To resolve this discrepancy, we jointly inverted the electromagnetic data for 4-layer models by including seismic depths to an interface between sedimentary units and to basement as explicit a priori constraints. We have also estimated the interconnected porosities, clay contents and pore-fluid resistivities of the sedimentary units from their electrical resistivities and seismic P-wave velocities using appropriate petrophysical models. In the interpretation of our preferred model, a shallow ˜40 m thick freshwater sandy aquifer with 85-100 Ωm resistivity, 10-32 per cent interconnected porosity and <13 per cent clay content overlies a 105-115 m thick conductive sequence of clay and intercalated salt-water-saturated sands with 15-20 Ωm total resistivity, 1-27 per cent interconnected porosity and 15-60 per cent clay content. A third ˜60 m thick sandy layer with 40-50 Ωm resistivity, 10-33 per cent interconnected porosity and <15
2D and 3D Numerical Simulations of Flux Cancellation
NASA Technical Reports Server (NTRS)
Karpen, Judith T.; DeVore, C.; Antiochos, S. K.; Linton, M. G.
2009-01-01
Cancellation of magnetic flux in the solar photosphere and chromosphere has been linked observationally and theoretically to a broad range of solar activity, from filament channel formation to CME initiation. Because this phenomenon is typically measured at only a single layer in the atmosphere, in the radial (line of sight) component of the magnetic field, the actual processes behind this observational signature are ambiguous. It is clear that reconnection is involved in some way, but the location of the reconnection sites and associated connectivity changes remain uncertain in most cases. We are using numerical modeling to demystify flux cancellation, beginning with the simplest possible configuration: a subphotospheric Lundquist flux tube surrounded by a potential field, immersed in a gravitationally stratified atmosphere, spanning many orders of magnitude in plasma beta. In this system, cancellation is driven slowly by a 2-cell circulation pattern imposed in the convection zone, such that the tops of the cells are located around the beta=1 level (i.e., the photosphere) and the flows converge and form a downdraft at the polarity inversion line; note however that no flow is imposed along the neutral line. We will present the results of 2D and 3D MHD-AMR simulations of flux cancellation, in which the flux at the photosphere begins in either an unsheared or sheared state. In all cases, a low-lying flux rope is formed by reconnection at the polarity inversion line within a few thousand seconds. The flux rope remains stable and does not rise, however, in contrast to models which do not include the presence of significant mass loading.
Realistic and efficient 2D crack simulation
NASA Astrophysics Data System (ADS)
Yadegar, Jacob; Liu, Xiaoqing; Singh, Abhishek
2010-04-01
Although numerical algorithms for 2D crack simulation have been studied in Modeling and Simulation (M&S) and computer graphics for decades, realism and computational efficiency are still major challenges. In this paper, we introduce a high-fidelity, scalable, adaptive and efficient/runtime 2D crack/fracture simulation system by applying the mathematically elegant Peano-Cesaro triangular meshing/remeshing technique to model the generation of shards/fragments. The recursive fractal sweep associated with the Peano-Cesaro triangulation provides efficient local multi-resolution refinement to any level-of-detail. The generated binary decomposition tree also provides efficient neighbor retrieval mechanism used for mesh element splitting and merging with minimal memory requirements essential for realistic 2D fragment formation. Upon load impact/contact/penetration, a number of factors including impact angle, impact energy, and material properties are all taken into account to produce the criteria of crack initialization, propagation, and termination leading to realistic fractal-like rubble/fragments formation. The aforementioned parameters are used as variables of probabilistic models of cracks/shards formation, making the proposed solution highly adaptive by allowing machine learning mechanisms learn the optimal values for the variables/parameters based on prior benchmark data generated by off-line physics based simulation solutions that produce accurate fractures/shards though at highly non-real time paste. Crack/fracture simulation has been conducted on various load impacts with different initial locations at various impulse scales. The simulation results demonstrate that the proposed system has the capability to realistically and efficiently simulate 2D crack phenomena (such as window shattering and shards generation) with diverse potentials in military and civil M&S applications such as training and mission planning.
Engineering light outcoupling in 2D materials.
Lien, Der-Hsien; Kang, Jeong Seuk; Amani, Matin; Chen, Kevin; Tosun, Mahmut; Wang, Hsin-Ping; Roy, Tania; Eggleston, Michael S; Wu, Ming C; Dubey, Madan; Lee, Si-Chen; He, Jr-Hau; Javey, Ali
2015-02-11
When light is incident on 2D transition metal dichalcogenides (TMDCs), it engages in multiple reflections within underlying substrates, producing interferences that lead to enhancement or attenuation of the incoming and outgoing strength of light. Here, we report a simple method to engineer the light outcoupling in semiconducting TMDCs by modulating their dielectric surroundings. We show that by modulating the thicknesses of underlying substrates and capping layers, the interference caused by substrate can significantly enhance the light absorption and emission of WSe2, resulting in a ∼11 times increase in Raman signal and a ∼30 times increase in the photoluminescence (PL) intensity of WSe2. On the basis of the interference model, we also propose a strategy to control the photonic and optoelectronic properties of thin-layer WSe2. This work demonstrates the utilization of outcoupling engineering in 2D materials and offers a new route toward the realization of novel optoelectronic devices, such as 2D LEDs and solar cells.
Functional characterization of CYP2D6 enhancer polymorphisms
Wang, Danxin; Papp, Audrey C.; Sun, Xiaochun
2015-01-01
CYP2D6 metabolizes nearly 25% of clinically used drugs. Genetic polymorphisms cause large inter-individual variability in CYP2D6 enzyme activity and are currently used as biomarker to predict CYP2D6 metabolizer phenotype. Previously, we had identified a region 115 kb downstream of CYP2D6 as enhancer for CYP2D6, containing two completely linked single nucleotide polymorphisms (SNPs), rs133333 and rs5758550, associated with enhanced transcription. However, the enhancer effect on CYP2D6 expression, and the causative variant, remained to be ascertained. To characterize the CYP2D6 enhancer element, we applied chromatin conformation capture combined with the next-generation sequencing (4C assays) and chromatin immunoprecipitation with P300 antibody, in HepG2 and human primary culture hepatocytes. The results confirmed the role of the previously identified enhancer region in CYP2D6 expression, expanding the number of candidate variants to three highly linked SNPs (rs133333, rs5758550 and rs4822082). Among these, only rs5758550 demonstrated regulating enhancer activity in a reporter gene assay. Use of clustered regularly interspaced short palindromic repeats mediated genome editing in HepG2 cells targeting suspected enhancer regions decreased CYP2D6 mRNA expression by 70%, only upon deletion of the rs5758550 region. These results demonstrate robust effects of both the enhancer element and SNP rs5758550 on CYP2D6 expression, supporting consideration of rs5758550 for CYP2D6 genotyping panels to yield more accurate phenotype prediction. PMID:25381333
2-D Coda and Direct Wave Attenuation Tomography in Northern Italy
Morasca, P; Mayeda, K; Gok, R; Phillips, W S; Malagnini, L
2007-10-17
A 1-D coda method was proposed by Mayeda et al. (2003) in order to obtain stable seismic source moment-rate spectra using narrowband coda envelope measurements. That study took advantage of the averaging nature of coda waves to derive stable amplitude measurements taking into account all propagation, site, and Sto-coda transfer function effects. Recently this methodology was applied to micro earthquake data sets from three sub-regions of northern Italy (i.e., western Alps, northern Apennines and eastern Alps). Since the study regions were small, ranging between local-to-near-regional distances, the simple 1-D path assumptions used in the coda method worked very well. The lateral complexity of this region would suggest, however, that a 2-D path correction might provide even better results if the datasets were combined, especially when paths traverse larger distances and complicated regions. The structural heterogeneity of northern Italy makes the region ideal to test the extent to which coda variance can be reduced further by using a 2-D Q tomography technique. The approach we use has been developed by Phillips et al. (2005) and is an extension of previous amplitude ratio techniques to remove source effects from the inversion. The method requires some assumptions such as isotropic source radiation which is generally true for coda waves. Our results are compared against direct Swave inversions for 1/Q and results from both share very similar attenuation features that coincide with known geologic structures. We compare our results with those derived from direct waves as well as some recent results from northern California obtained by Mayeda et al. (2005) which tested the same tomographic methodology applied in this study to invert for 1/Q. We find that 2-D coda path corrections for this region significantly improve upon the 1-D corrections, in contrast to California where only a marginal improvement was observed. We attribute this difference to stronger lateral
Xie, Donghao; Ji, Ding-Kun; Zhang, Yue; Cao, Jun; Zheng, Hu; Liu, Lin; Zang, Yi; Li, Jia; Chen, Guo-Rong; James, Tony D; He, Xiao-Peng
2016-08-01
Here we demonstrate that 2D MoS2 can enhance the receptor-targeting and imaging ability of a fluorophore-labelled ligand. The 2D MoS2 has an enhanced working concentration range when compared with graphene oxide, resulting in the improved imaging of both cell and tissue samples.
Second to fourth digit ratio (2D:4D) and concentrations of circulating sex hormones in adulthood
2011-01-01
Background The second to fourth digit ratio (2D:4D) is used as a marker of prenatal sex hormone exposure. The objective of this study was to examine whether circulating concentrations of sex hormones and SHBG measured in adulthood was associated with 2D:4D. Methods This analysis was based on a random sample from the Melbourne Collaborative Cohort Study. The sample consisted of of 1036 men and 620 post-menopausal women aged between 39 and 70 at the time of blood draw. Concentrations of circulating sex hormones were measured from plasma collected at baseline (1990-1994), while digit length was measured from hand photocopies taken during a recent follow-up (2003-2009). The outcome measures were circulating concentrations of testosterone, oestradiol, dehydroepiandrosterone sulphate, androstenedione, Sex Hormone Binding Globulin, androstenediol glucoronide for men only and oestrone sulphate for women only. Free testosterone and oestradiol were estimated using standard formulae derived empirically. Predicted geometric mean hormone concentrations (for tertiles of 2D:4D) and conditional correlation coefficients (for continuous 2D:4D) were obtained using mixed effects linear regression models. Results No strong associations were observed between 2D:4D measures and circulating concentrations of hormones for men or women. For males, right 2D:4D was weakly inversely associated with circulating testosterone (predicted geometric mean testosterone was 15.9 and 15.0 nmol/L for the lowest and highest tertiles of male right 2D:4D respectively (P-trend = 0.04). There was a similar weak association between male right 2D:4D and the ratio of testosterone to oestradiol. These associations were not evident in analyses of continuous 2D:4D. Conclusions There were no strong associations between any adult circulating concentration of sex hormone or SHGB and 2D:4D. These results contribute to the growing body of evidence indicating that 2D:4D is unrelated to adult sex hormone concentrations
CYP2D6: novel genomic structures and alleles
Kramer, Whitney E.; Walker, Denise L.; O’Kane, Dennis J.; Mrazek, David A.; Fisher, Pamela K.; Dukek, Brian A.; Bruflat, Jamie K.; Black, John L.
2010-01-01
Objective CYP2D6 is a polymorphic gene. It has been observed to be deleted, to be duplicated and to undergo recombination events involving the CYP2D7 pseudogene and surrounding sequences. The objective of this study was to discover the genomic structure of CYP2D6 recombinants that interfere with clinical genotyping platforms that are available today. Methods Clinical samples containing rare homozygous CYP2D6 alleles, ambiguous readouts, and those with duplication signals and two different alleles were analyzed by long-range PCR amplification of individual genes, PCR fragment analysis, allele-specific primer extension assay, and DNA sequencing to characterize alleles and genomic structure. Results Novel alleles, genomic structures, and the DNA sequence of these structures are described. Interestingly, in 49 of 50 DNA samples that had CYP2D6 gene duplications or multiplications where two alleles were detected, the chromosome containing the duplication or multiplication had identical tandem alleles. Conclusion Several new CYP2D6 alleles and genomic structures are described which will be useful for CYP2D6 genotyping. The findings suggest that the recombination events responsible for CYP2D6 duplications and multiplications are because of mechanisms other than interchromosomal crossover during meiosis. PMID:19741566
In situ fluid typing and quantification with 1D and 2D NMR logging.
Sun, Boqin
2007-05-01
In situ nuclear magnetic resonance (NMR) fluid typing has recently gained momentum due to data acquisition and inversion algorithm enhancement of NMR logging tools. T(2) distributions derived from NMR logging contain information on bulk fluids and pore size distributions. However, the accuracy of fluid typing is greatly overshadowed by the overlap between T(2) peaks arising from different fluids with similar apparent T(2) relaxation times. Nevertheless, the shapes of T(2) distributions from different fluid components are often different and can be predetermined. Inversion with predetermined T(2) distributions allows us to perform fluid component decomposition to yield individual fluid volume ratios. Another effective method for in situ fluid typing is two-dimensional (2D) NMR logging, which results in proton population distribution as a function of T(2) relaxation time and fluid diffusion coefficient (or T(1) relaxation time). Since diffusion coefficients (or T(1) relaxation time) for different fluid components can be very different, it is relatively easy to separate oil (especially heavy oil) from water signal in a 2D NMR map and to perform accurate fluid typing. Combining NMR logging with resistivity and/or neutron/density logs provides a third method for in situ fluid typing. We shall describe these techniques with field examples. PMID:17466778
A fast and low-loss 3-D magnetotelluric inversion method with parallel structure
NASA Astrophysics Data System (ADS)
Zhang, K.; Zhang, L.
2013-12-01
The 2D assumption is valid in some cases of interpretation, the approximation does not work in most cases, especially in areas with complex geo-electrical structure. A number of 3D magentotelluric inversion methods has been proposed, including RRI, CG, QA, NLCG. Each of those methods has its own advantages and disadvantages. However, as the 3D dataset and mesh grid require greater computer memory and calculation time than 2D methods, the efficiency of the inversion scheme become a key concern of 3D inversions. We chose NLCG as the optimization method for inversion. A parameter matrix related with the current resisitivity model and data error is proposed to approximate the Hessian matrix. So four forward calculation can be avoided each iteration. In addition, OPENMP parallel API is utilized to establish an effecient parallel inversion structure based on frequency to reduce computation time. And both synthetic and field data are used to test the efficiency of the inversion and the preconditioning method. The model consists of four square prisms residing in a halfspace. The total computation time of invertion is 706s (use one PC). Fiugre 1 shows the inversion result. The abnormal bodies can be distinguished clearly. Field data from the NIHE dataset in China is used to verify the reliability and efficiency of the 3D inversion method. The total computation time is about 25 minutes after 60 iterations on one PC. Totally, four electrical layers can be corresponded to the four stratum in 3D AMT inversion model, and the faults can be seen clearly. In addition, we can get more information about fault and alteration interface from constrained inversion result. Finally, the inversion method is very fast and low-loss, so it can be used in modern PC (need only one PC) with few hardware constraints. (a): initial model; (b): inversion depth slices (1-4km); (c): fitting error (a): AMT 3D slice; (b): CSAMT 2D model; (c): TEM 1D model; (d): SIP 2D model; (e) AMT 3D constrained
Interpretation of Magnetic Phase Anomalies over 2D Tabular Bodies
NASA Astrophysics Data System (ADS)
Subrahmanyam, M.
2016-05-01
In this study, phase angle (inverse tangent of the ratio of the horizontal to vertical gradients of magnetic anomalies) profile over two-dimensional tabular bodies has been subjected to detailed analysis for determining the source parameters. Distances between certain characteristic positions on this phase curve are related to the parameters of two-dimensional tabular magnetic sources. In this paper, I have derived the mathematical expressions for these relations. It has been demonstrated here that for locating the origin of the 2D tabular source, knowledge on the type of the model (contact, sheet, dyke, and fault) is not necessary. A procedure is evolved to determine the location, depth, width and magnetization angle of the 2D sources from the mathematical expressions. The method is tested on real field data. The effect of the overlapping bodies is also discussed with two synthetic examples. The interpretation technique is developed for contact, sheet, dike and inclined fault bodies.
Comparison of 2D and 3D gamma analyses
Pulliam, Kiley B.; Huang, Jessie Y.; Howell, Rebecca M.; Followill, David; Kry, Stephen F.; Bosca, Ryan; O’Daniel, Jennifer
2014-02-15
Purpose: As clinics begin to use 3D metrics for intensity-modulated radiation therapy (IMRT) quality assurance, it must be noted that these metrics will often produce results different from those produced by their 2D counterparts. 3D and 2D gamma analyses would be expected to produce different values, in part because of the different search space available. In the present investigation, the authors compared the results of 2D and 3D gamma analysis (where both datasets were generated in the same manner) for clinical treatment plans. Methods: Fifty IMRT plans were selected from the authors’ clinical database, and recalculated using Monte Carlo. Treatment planning system-calculated (“evaluated dose distributions”) and Monte Carlo-recalculated (“reference dose distributions”) dose distributions were compared using 2D and 3D gamma analysis. This analysis was performed using a variety of dose-difference (5%, 3%, 2%, and 1%) and distance-to-agreement (5, 3, 2, and 1 mm) acceptance criteria, low-dose thresholds (5%, 10%, and 15% of the prescription dose), and data grid sizes (1.0, 1.5, and 3.0 mm). Each comparison was evaluated to determine the average 2D and 3D gamma, lower 95th percentile gamma value, and percentage of pixels passing gamma. Results: The average gamma, lower 95th percentile gamma value, and percentage of passing pixels for each acceptance criterion demonstrated better agreement for 3D than for 2D analysis for every plan comparison. The average difference in the percentage of passing pixels between the 2D and 3D analyses with no low-dose threshold ranged from 0.9% to 2.1%. Similarly, using a low-dose threshold resulted in a difference between the mean 2D and 3D results, ranging from 0.8% to 1.5%. The authors observed no appreciable differences in gamma with changes in the data density (constant difference: 0.8% for 2D vs 3D). Conclusions: The authors found that 3D gamma analysis resulted in up to 2.9% more pixels passing than 2D analysis. It must
Perspectives for spintronics in 2D materials
NASA Astrophysics Data System (ADS)
Han, Wei
2016-03-01
The past decade has been especially creative for spintronics since the (re)discovery of various two dimensional (2D) materials. Due to the unusual physical characteristics, 2D materials have provided new platforms to probe the spin interaction with other degrees of freedom for electrons, as well as to be used for novel spintronics applications. This review briefly presents the most important recent and ongoing research for spintronics in 2D materials.
Quantitative 2D liquid-state NMR.
Giraudeau, Patrick
2014-06-01
Two-dimensional (2D) liquid-state NMR has a very high potential to simultaneously determine the absolute concentration of small molecules in complex mixtures, thanks to its capacity to separate overlapping resonances. However, it suffers from two main drawbacks that probably explain its relatively late development. First, the 2D NMR signal is strongly molecule-dependent and site-dependent; second, the long duration of 2D NMR experiments prevents its general use for high-throughput quantitative applications and affects its quantitative performance. Fortunately, the last 10 years has witnessed an increasing number of contributions where quantitative approaches based on 2D NMR were developed and applied to solve real analytical issues. This review aims at presenting these recent efforts to reach a high trueness and precision in quantitative measurements by 2D NMR. After highlighting the interest of 2D NMR for quantitative analysis, the different strategies to determine the absolute concentrations from 2D NMR spectra are described and illustrated by recent applications. The last part of the manuscript concerns the recent development of fast quantitative 2D NMR approaches, aiming at reducing the experiment duration while preserving - or even increasing - the analytical performance. We hope that this comprehensive review will help readers to apprehend the current landscape of quantitative 2D NMR, as well as the perspectives that may arise from it.
Efficient 2D MRI relaxometry using compressed sensing
NASA Astrophysics Data System (ADS)
Bai, Ruiliang; Cloninger, Alexander; Czaja, Wojciech; Basser, Peter J.
2015-06-01
Potential applications of 2D relaxation spectrum NMR and MRI to characterize complex water dynamics (e.g., compartmental exchange) in biology and other disciplines have increased in recent years. However, the large amount of data and long MR acquisition times required for conventional 2D MR relaxometry limits its applicability for in vivo preclinical and clinical MRI. We present a new MR pipeline for 2D relaxometry that incorporates compressed sensing (CS) as a means to vastly reduce the amount of 2D relaxation data needed for material and tissue characterization without compromising data quality. Unlike the conventional CS reconstruction in the Fourier space (k-space), the proposed CS algorithm is directly applied onto the Laplace space (the joint 2D relaxation data) without compressing k-space to reduce the amount of data required for 2D relaxation spectra. This framework is validated using synthetic data, with NMR data acquired in a well-characterized urea/water phantom, and on fixed porcine spinal cord tissue. The quality of the CS-reconstructed spectra was comparable to that of the conventional 2D relaxation spectra, as assessed using global correlation, local contrast between peaks, peak amplitude and relaxation parameters, etc. This result brings this important type of contrast closer to being realized in preclinical, clinical, and other applications.
'Brukin2D': a 2D visualization and comparison tool for LC-MS data
Tsagkrasoulis, Dimosthenis; Zerefos, Panagiotis; Loudos, George; Vlahou, Antonia; Baumann, Marc; Kossida, Sophia
2009-01-01
Background Liquid Chromatography-Mass Spectrometry (LC-MS) is a commonly used technique to resolve complex protein mixtures. Visualization of large data sets produced from LC-MS, namely the chromatogram and the mass spectra that correspond to its compounds is the focus of this work. Results The in-house developed 'Brukin2D' software, built in Matlab 7.4, which is presented here, uses the compound data that are exported from the Bruker 'DataAnalysis' program, and depicts the mean mass spectra of all the chromatogram compounds from one LC-MS run, in one 2D contour/density plot. Two contour plots from different chromatograph runs can then be viewed in the same window and automatically compared, in order to find their similarities and differences. The results of the comparison can be examined through detailed mass quantification tables, while chromatogram compound statistics are also calculated during the procedure. Conclusion 'Brukin2D' provides a user-friendly platform for quick, easy and integrated view of complex LC-MS data. The software is available at . PMID:19534737
Canard configured aircraft with 2-D nozzle
NASA Technical Reports Server (NTRS)
Child, R. D.; Henderson, W. P.
1978-01-01
A closely-coupled canard fighter with vectorable two-dimensional nozzle was designed for enhanced transonic maneuvering. The HiMAT maneuver goal of a sustained 8g turn at a free-stream Mach number of 0.9 and 30,000 feet was the primary design consideration. The aerodynamic design process was initiated with a linear theory optimization minimizing the zero percent suction drag including jet effects and refined with three-dimensional nonlinear potential flow techniques. Allowances were made for mutual interference and viscous effects. The design process to arrive at the resultant configuration is described, and the design of a powered 2-D nozzle model to be tested in the LRC 16-foot Propulsion Wind Tunnel is shown.
Mehl, S.; Hill, M.C.
2001-01-01
Five common numerical techniques for solving the advection-dispersion equation (finite difference, predictor corrector, total variation diminishing, method of characteristics, and modified method of characteristics) were tested using simulations of a controlled conservative tracer-test experiment through a heterogeneous, two-dimensional sand tank. The experimental facility was constructed using discrete, randomly distributed, homogeneous blocks of five sand types. This experimental model provides an opportunity to compare the solution techniques: the heterogeneous hydraulic-conductivity distribution of known structure can be accurately represented by a numerical model, and detailed measurements can be compared with simulated concentrations and total flow through the tank. The present work uses this opportunity to investigate how three common types of results - simulated breakthrough curves, sensitivity analysis, and calibrated parameter values - change in this heterogeneous situation given the different methods of simulating solute transport. The breakthrough curves show that simulated peak concentrations, even at very fine grid spacings, varied between the techniques because of different amounts of numerical dispersion. Sensitivity-analysis results revealed: (1) a high correlation between hydraulic conductivity and porosity given the concentration and flow observations used, so that both could not be estimated; and (2) that the breakthrough curve data did not provide enough information to estimate individual values of dispersivity for the five sands. This study demonstrates that the choice of assigned dispersivity and the amount of numerical dispersion present in the solution technique influence estimated hydraulic conductivity values to a surprising degree.
NASA Astrophysics Data System (ADS)
Medvedev, S. N.
2015-10-01
Stacking by CDP technique is inapplicable for processing of data from bottom seismic stations or acoustic sonobuoys. In addition, big amount of unknown velocity and structural parameters of the real layered medium do not allow these parameters to be defined by standard processing methods. Local sloped stacking is proposed for simultaneous obtaining the stacked tracks, travel time curve of a chosen wave, and the first derivative of this travel time curve. The additionally defined parameters are second derivative of this travel time curve and integrated average of squared travel time curve. These data are sufficient to reduce the amount of unknown parameters (down to one-two for each boundary) when layer-by-layer top-to-bottom processing. As a result, the stable estimates of velocity parameters of the layered (isotropic or anisotropic) medium can be obtained and stacked tracks obtained by local sloped staking can be transformed into boundaries in the time and depth sections.
NASA Astrophysics Data System (ADS)
Palit, S.; Ray, S.; Chakrabarti, S. K.
2016-05-01
X-rays and gamma-rays from astronomical sources such as solar flares are mostly absorbed by the Earth's atmosphere. Resulting electron-ion production rate as a function of height depends on the intensity and wavelength of the injected spectrum and therefore the effects vary from one source to another. In other words, the ion density vs. altitude profile has the imprint of the incident photon spectrum. In this paper, we investigate whether we can invert the problem uniquely by deconvolution of the VLF amplitude signal to obtain the details of the injected spectrum. We find that it is possible to do this up to a certain accuracy. This leads us to the possibility of uninterrupted observation of X-ray photon spectra of solar flares that are often hindered by the restricted observation window of space satellites to avoid charge particle damages. Such continuous means of observation are essential in deriving information on time evolution of physical processes related to electron acceleration and interaction with plasma in solar atmosphere. Our method is useful to carry out a similar exercise to infer the spectra of more energetic events such as the Gamma Ray Bursts (GRBs), Soft Gamma-ray Repeaters (SGRs) etc., by probing even the lower part of the Earth's atmosphere. We thus show that to certain extent, the Earth's atmosphere could be used as a gigantic detector of relatively strong astronomical events.
Emerging and potential opportunities for 2D flexible nanoelectronics
NASA Astrophysics Data System (ADS)
Zhu, Weinan; Park, Saungeun; Akinwande, Deji
2016-05-01
The last 10 years have seen the emergence of two-dimensional (2D) nanomaterials such as graphene, transition metal dichalcogenides (TMDs), and black phosphorus (BP) among the growing portfolio of layered van der Waals thin films. Graphene, the prototypical 2D material has advanced rapidly in device, circuit and system studies that has resulted in commercial large-area applications. In this work, we provide a perspective of the emerging and potential translational applications of 2D materials including semiconductors, semimetals, and insulators that comprise the basic material set for diverse nanosystems. Applications include RF transceivers, smart systems, the so-called internet of things, and neurotechnology. We will review the DC and RF electronic performance of graphene and BP thin film transistors. 2D materials at sub-um channel length have so far enabled cut-off frequencies from baseband to 100GHz suitable for low-power RF and sub-THz concepts.
Double resonance rotational spectroscopy of CH2D+
NASA Astrophysics Data System (ADS)
Töpfer, Matthias; Jusko, Pavol; Schlemmer, Stephan; Asvany, Oskar
2016-09-01
Context. Deuterated forms of CH are thought to be responsible for deuterium enrichment in lukewarm astronomical environments. There is no unambiguous detection of CH2D+ in space to date. Aims: Four submillimetre rotational lines of CH2D+ are documented in the literature. Our aim is to present a complete dataset of highly resolved rotational lines, including millimetre (mm) lines needed for a potential detection. Methods: We used a low-temperature ion trap and applied a novel IR-mm-wave double resonance method to measure the rotational lines of CH2D+. Results: We measured 21 low-lying (J ≤ 4) rotational transitions of CH2D+ between 23 GHz and 1.1 THz with accuracies close to 2 ppb.
Metrology for graphene and 2D materials
NASA Astrophysics Data System (ADS)
Pollard, Andrew J.
2016-09-01
The application of graphene, a one atom-thick honeycomb lattice of carbon atoms with superlative properties, such as electrical conductivity, thermal conductivity and strength, has already shown that it can be used to benefit metrology itself as a new quantum standard for resistance. However, there are many application areas where graphene and other 2D materials, such as molybdenum disulphide (MoS2) and hexagonal boron nitride (h-BN), may be disruptive, areas such as flexible electronics, nanocomposites, sensing and energy storage. Applying metrology to the area of graphene is now critical to enable the new, emerging global graphene commercial world and bridge the gap between academia and industry. Measurement capabilities and expertise in a wide range of scientific areas are required to address this challenge. The combined and complementary approach of varied characterisation methods for structural, chemical, electrical and other properties, will allow the real-world issues of commercialising graphene and other 2D materials to be addressed. Here, examples of metrology challenges that have been overcome through a multi-technique or new approach are discussed. Firstly, the structural characterisation of defects in both graphene and MoS2 via Raman spectroscopy is described, and how nanoscale mapping of vacancy defects in graphene is also possible using tip-enhanced Raman spectroscopy (TERS). Furthermore, the chemical characterisation and removal of polymer residue on chemical vapour deposition (CVD) grown graphene via secondary ion mass spectrometry (SIMS) is detailed, as well as the chemical characterisation of iron films used to grow large domain single-layer h-BN through CVD growth, revealing how contamination of the substrate itself plays a role in the resulting h-BN layer. In addition, the role of international standardisation in this area is described, outlining the current work ongoing in both the International Organization of Standardization (ISO) and the
NASA Astrophysics Data System (ADS)
Chen, R.; Zhao, X.; Yao, H.; He, X.; Zeng, P.; Chang, F.; Yang, Y.; Zhang, X.; Xi, X.; He, L.
2015-12-01
Induced polarization (IP) is a powerful tool in metalliferous ore exploration. However, there are many sources, such as clay and graphite, which can generate IP anomaly. Spectral induced polarization (SIP) measures IP response on a wide frequency range. This method provides a way to discriminate IP response generated by metalliferous ore or other objects. The best way to explore metalliferous ore is 3D SIP exploration. However, if we consider the exploration cost and efficiency, we can use SIP profiling to find an anomaly, and then use 2D/3D SIP sounding to characterize the anomaly. Based on above idea, we used a large-scale distributed SIP measurement system which can realize 800 sounding sites in one direction at the same time. This system can be used for SIP profiling, 2D/3D SIP sounding with high efficiency, high resolution, and large depth of investigation (> 1000 m). Qiushuwan copper - molybdenum deposit is located in Nanyang city, Henan province, China. It is only a middle-size deposit although over 100 holes were drilled and over 40 years of exploration were spent because of very complex geological setting. We made SIP measurement over 100 rock and ore samples to discriminate IP responses of ore and rock containing graphite. Then we carried out 7 lines of 2D SIP exploration with the depth of investigation great than 1000 m. The minimum electode spacing for potential difference is only 20 m. And we increase the spacing of current electodes at linear scale. This acquisition setting ensures high density data acquired and high quality data acquisition. Modeling and inversion result proves that we can get underground information with high resolution by our method. Our result shows that there exists a strong SIP response related to ore body in depth > 300 m. Pseudo-3D inversion of five 2D SIP sounding lines shows the location and size of IP anomaly. The new drillings based our result found a big copper-molybdenum ore body in new position with depth > 300 m and
Use of the 'Precessions' process for prepolishing and correcting 2D & 2(1/2)D form.
Walker, David D; Freeman, Richard; Morton, Roger; McCavana, Gerry; Beaucamp, Anthony
2006-11-27
The Precessions process polishes complex surfaces from the ground state preserving the ground-in form, and subsequently rectifies measured form errors. Our first paper introduced the technology and focused on the novel tooling. In this paper we describe the unique CNC machine tools and how they operate in polishing and correcting form. Experimental results demonstrate both the '2D' and '2(1/2)D' form-correction modes, as applied to aspheres with rotationally-symmetric target-form.
The Estimation and Inversion of Magnetotelluric Data with Static Shift
NASA Astrophysics Data System (ADS)
Wang, X.; Zhou, J.; Zhang, J.; Min, G.; Xia, S.
2015-12-01
IntroductionIn magnetotelluric sounding data processing, the static shift correction is one of the most important steps. Due to the complexity of near-surface inhomogeneous bodies distribution, it is difficult to estimate the static shift of measured data. For this problem, we put forward on the basis of the inversion model for static shift estimation, and reconstructed the initial model with using the original data for 2D or 3D inversion. Estimation and Inversion methodThe magnetotelluric impedance phase has the characteristics of not influenced by the static shift in Two-dimensional electrical structure. The objective function for static shift estimation can be constructed based on impedance phase data. On the basis of normal inversion, utilizing one-dimensional linear search algorithm, combined with the forward modeling, the MT static shift can be estimated.Using estimation results for translation of anomaly measured curve. According to the inversion(1-D) of these translated curve, the initial model for two-dimensional or two-dimensional inversion can be reconstructed. On this basis, we do inversion for the original data, which not only can effectively eliminate the influence of static shift on the deep structure of inversion model, but also can get the right shallow electrical structure in the inversionConclusionThe estimation value of static shift based on impedance phase can be close to the true value. This estimation results can be used to modify the initial model, which makes the deep electric structure of the model more reasonable. On this basis, the inversion of the original data can ensure the correctness of the final inversion results (including shallow and deep).Acknowledgement This paper is supported by National Natural Science Foundation (41274078) and National 863 High Technology Research and Development Program (2014AA06A612).Reference[1] deGroot-Hedlin C. Removal of static shift in two dimensions by regularized inversion[J]. Geophysics, 1991, 56
2D materials for nanophotonic devices
NASA Astrophysics Data System (ADS)
Xu, Renjing; Yang, Jiong; Zhang, Shuang; Pei, Jiajie; Lu, Yuerui
2015-12-01
Two-dimensional (2D) materials have become very important building blocks for electronic, photonic, and phononic devices. The 2D material family has four key members, including the metallic graphene, transition metal dichalcogenide (TMD) layered semiconductors, semiconducting black phosphorous, and the insulating h-BN. Owing to the strong quantum confinements and defect-free surfaces, these atomically thin layers have offered us perfect platforms to investigate the interactions among photons, electrons and phonons. The unique interactions in these 2D materials are very important for both scientific research and application engineering. In this talk, I would like to briefly summarize and highlight the key findings, opportunities and challenges in this field. Next, I will introduce/highlight our recent achievements. We demonstrated atomically thin micro-lens and gratings using 2D MoS2, which is the thinnest optical component around the world. These devices are based on our discovery that the elastic light-matter interactions in highindex 2D materials is very strong. Also, I would like to introduce a new two-dimensional material phosphorene. Phosphorene has strongly anisotropic optical response, which creates 1D excitons in a 2D system. The strong confinement in phosphorene also enables the ultra-high trion (charged exciton) binding energies, which have been successfully measured in our experiments. Finally, I will briefly talk about the potential applications of 2D materials in energy harvesting.
2D materials: to graphene and beyond.
Mas-Ballesté, Rubén; Gómez-Navarro, Cristina; Gómez-Herrero, Julio; Zamora, Félix
2011-01-01
This review is an attempt to illustrate the different alternatives in the field of 2D materials. Graphene seems to be just the tip of the iceberg and we show how the discovery of alternative 2D materials is starting to show the rest of this iceberg. The review comprises the current state-of-the-art of the vast literature in concepts and methods already known for isolation and characterization of graphene, and rationalizes the quite disperse literature in other 2D materials such as metal oxides, hydroxides and chalcogenides, and metal-organic frameworks.
3D geophysical inversion for contact surfaces
NASA Astrophysics Data System (ADS)
Lelièvre, Peter; Farquharson, Colin
2014-05-01
geophysical models can be specified using the same parameterization: they are, in essence, the same Earth model. We solve for the locations of the nodes through a Particle Swarm Optimization strategy and follow this with a more rigorous stochastic sampling to provide likelihood information. Such global optimization methods introduce high computational costs; to provide computationally feasible inversion methods, we reduce the dimensionality of the problem by parameterizing the nodes in a coarse representation of the geological wireframe model and we use splines (2D) or surface subdivision (3D) to refine further. This also provides a simple and effective way to regularize the inverse problem.
2-d Finite Element Code Postprocessor
1996-07-15
ORION is an interactive program that serves as a postprocessor for the analysis programs NIKE2D, DYNA2D, TOPAZ2D, and CHEMICAL TOPAZ2D. ORION reads binary plot files generated by the two-dimensional finite element codes currently used by the Methods Development Group at LLNL. Contour and color fringe plots of a large number of quantities may be displayed on meshes consisting of triangular and quadrilateral elements. ORION can compute strain measures, interface pressures along slide lines, reaction forcesmore » along constrained boundaries, and momentum. ORION has been applied to study the response of two-dimensional solids and structures undergoing finite deformations under a wide variety of large deformation transient dynamic and static problems and heat transfer analyses.« less
Ginsparg, P.
1991-01-01
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
Ginsparg, P.
1991-12-31
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
Chemical Approaches to 2D Materials.
Samorì, Paolo; Palermo, Vincenzo; Feng, Xinliang
2016-08-01
Chemistry plays an ever-increasing role in the production, functionalization, processing and applications of graphene and other 2D materials. This special issue highlights a selection of enlightening chemical approaches to 2D materials, which nicely reflect the breadth of the field and convey the excitement of the individuals involved in it, who are trying to translate graphene and related materials from the laboratory into a real, high-impact technology. PMID:27478083
Chemical Approaches to 2D Materials.
Samorì, Paolo; Palermo, Vincenzo; Feng, Xinliang
2016-08-01
Chemistry plays an ever-increasing role in the production, functionalization, processing and applications of graphene and other 2D materials. This special issue highlights a selection of enlightening chemical approaches to 2D materials, which nicely reflect the breadth of the field and convey the excitement of the individuals involved in it, who are trying to translate graphene and related materials from the laboratory into a real, high-impact technology.
Electrical resistivity tomography applied to a complex lava dome: 2D and 3D models comparison
NASA Astrophysics Data System (ADS)
Portal, Angélie; Fargier, Yannick; Lénat, Jean-François; Labazuy, Philippe
2015-04-01
The study of volcanic domes growth (e.g. St. Helens, Unzen, Montserrat) shows that it is often characterized by a succession of extrusion phases, dome explosions and collapse events. Lava dome eruptive activity may last from days to decades. Therefore, their internal structure, at the end of the eruption, is complex and includes massive extrusions and lava lobes, talus and pyroclastic deposits as well as hydrothermal alteration. The electrical resistivity tomography (ERT) method, initially developed for environmental and engineering exploration, is now commonly used for volcano structure imaging. Because a large range of resistivity values is often observed in volcanic environments, the method is well suited to study the internal structure of volcanic edifices. We performed an ERT survey on an 11ka years old trachytic lava dome, the Puy de Dôme volcano (French Massif Central). The analysis of a recent high resolution DEM (LiDAR 0.5 m), as well as other geophysical data, strongly suggest that the Puy de Dôme is a composite dome. 11 ERT profiles have been carried out, both at the scale of the entire dome (base diameter of ~2 km and height of 400 m) on the one hand, and at a smaller scale on the summit part on the other hand. Each profile is composed of 64 electrodes. Three different electrode spacing have been used depending on the study area (35 m for the entire dome, 10 m and 5 m for its summit part). Some profiles were performed with half-length roll-along acquisitions, in order to keep a good trade-off between depth of investigation and resolution. Both Wenner-alpha and Wenner-Schlumberger protocols were used. 2-D models of the electrical resistivity distribution were computed using RES2DINV software. In order to constrain inversion models interpretation, the depth of investigation (DOI) method was applied to those results. It aims to compute a sensitivity index on inversion results, illustrating how the data influence the model and constraining models
Yang, Li-Ming; Dornfeld, Matthew; Frauenheim, Thomas; Ganz, Eric
2015-10-21
We predict a highly stable and robust atomically thin gold monolayer with a hexagonal close packed lattice stabilized by metallic bonding with contributions from strong relativistic effects and aurophilic interactions. We have shown that the framework of the Au monolayer can survive 10 ps MD annealing simulations up to 1400 K. The framework is also able to survive large motions out of the plane. Due to the smaller number of bonds per atom in the 2D layer compared to the 3D bulk we observe significantly enhanced energy per bond (0.94 vs. 0.52 eV per bond). This is similar to the increase in bond strength going from 3D diamond to 2D graphene. It is a non-magnetic metal, and was found to be the global minima in the 2D space. Phonon dispersion calculations demonstrate high kinetic stability with no negative modes. This 2D gold monolayer corresponds to the top monolayer of the bulk Au(111) face-centered cubic lattice. The close-packed lattice maximizes the aurophilic interactions. We find that the electrons are completely delocalized in the plane and behave as 2D nearly free electron gas. We hope that the present work can inspire the experimental fabrication of novel free standing 2D metal systems.
2d index and surface operators
NASA Astrophysics Data System (ADS)
Gadde, Abhijit; Gukov, Sergei
2014-03-01
In this paper we compute the superconformal index of 2d (2, 2) supersymmetric gauge theories. The 2d superconformal index, a.k.a. flavored elliptic genus, is computed by a unitary matrix integral much like the matrix integral that computes the 4d superconformal index. We compute the 2d index explicitly for a number of examples. In the case of abelian gauge theories we see that the index is invariant under flop transition and under CY-LG correspondence. The index also provides a powerful check of the Seiberg-type duality for non-abelian gauge theories discovered by Hori and Tong. In the later half of the paper, we study half-BPS surface operators in = 2 super-conformal gauge theories. They are engineered by coupling the 2d (2, 2) supersymmetric gauge theory living on the support of the surface operator to the 4d = 2 theory, so that different realizations of the same surface operator with a given Levi type are related by a 2d analogue of the Seiberg duality. The index of this coupled system is computed by using the tools developed in the first half of the paper. The superconformal index in the presence of surface defect is expected to be invariant under generalized S-duality. We demonstrate that it is indeed the case. In doing so the Seiberg-type duality of the 2d theory plays an important role.
Qu, Qiang; Qu, Jian; Han, Lu; Zhan, Min; Wu, Lan-xiang; Zhang, Yi-wen; Zhang, Wei; Zhou, Hong-hao
2014-01-01
Aim: Herbal products have been widely used, and the safety of herb-drug interactions has aroused intensive concerns. This study aimed to investigate the effects of phytochemicals on the catalytic activities of human CYP2D6*1 and CYP2D6*10 in vitro. Methods: HepG2 cells were stably transfected with CYP2D6*1 and CYP2D6*10 expression vectors. The metabolic kinetics of the enzymes was studied using HPLC and fluorimetry. Results: HepG2-CYP2D6*1 and HepG2-CYP2D6*10 cell lines were successfully constructed. Among the 63 phytochemicals screened, 6 compounds, including coptisine sulfate, bilobalide, schizandrin B, luteolin, schizandrin A and puerarin, at 100 μmol/L inhibited CYP2D6*1- and CYP2D6*10-mediated O-demethylation of a coumarin compound AMMC by more than 50%. Furthermore, the inhibition by these compounds was dose-dependent. Eadie-Hofstee plots demonstrated that these compounds competitively inhibited CYP2D6*1 and CYP2D6*10. However, their Ki values for CYP2D6*1 and CYP2D6*10 were very close, suggesting that genotype-dependent herb-drug inhibition was similar between the two variants. Conclusion: Six phytochemicals inhibit CYP2D6*1 and CYP2D6*10-mediated catalytic activities in a dose-dependent manner in vitro. Thus herbal products containing these phytochemicals may inhibit the in vivo metabolism of co-administered drugs whose primary route of elimination is CYP2D6. PMID:24786236
Stöbe, Stephan; Tarr, Adrienn; Pfeiffer, Dietrich; Hagendorff, Andreas
2014-01-01
Comparison of 3D and 2D speckle tracking performed on standard 2D and triplane 2D datasets of normal and pathological left ventricular (LV) wall-motion patterns with a focus on the effect that 3D volume rate (3DVR), image quality and tracking artifacts have on the agreement between 2D and 3D speckle tracking. 37 patients with normal LV function and 18 patients with ischaemic wall-motion abnormalities underwent 2D and 3D echocardiography, followed by offline speckle tracking measurements. The values of 3D global, regional and segmental strain were compared with the standard 2D and triplane 2D strain values. Correlation analysis with the LV ejection fraction (LVEF) was also performed. The 3D and 2D global strain values correlated good in both normally and abnormally contracting hearts, though systematic differences between the two methods were observed. Of the 3D strain parameters, the area strain showed the best correlation with the LVEF. The numerical agreement of 3D and 2D analyses varied significantly with the volume rate and image quality of the 3D datasets. The highest correlation between 2D and 3D peak systolic strain values was found between 3D area and standard 2D longitudinal strain. Regional wall-motion abnormalities were similarly detected by 2D and 3D speckle tracking. 2DST of triplane datasets showed similar results to those of conventional 2D datasets. 2D and 3D speckle tracking similarly detect normal and pathological wall-motion patterns. Limited image quality has a significant impact on the agreement between 3D and 2D numerical strain values. PMID:26693303
2D Time-lapse Seismic Tomography Using An Active Time Constraint (ATC) Approach
We propose a 2D seismic time-lapse inversion approach to image the evolution of seismic velocities over time and space. The forward modeling is based on solving the eikonal equation using a second-order fast marching method. The wave-paths are represented by Fresnel volumes rathe...
Internetwork magnetic field as revealed by two-dimensional inversions
NASA Astrophysics Data System (ADS)
Danilovic, S.; van Noort, M.; Rempel, M.
2016-09-01
Context. Properties of magnetic field in the internetwork regions are still fairly unknown because of rather weak spectropolarimetric signals. Aims: We address the matter by using the two-dimensional (2D) inversion code, which is able to retrieve the information on smallest spatial scales up to the diffraction limit, while being less susceptible to noise than most of the previous methods used. Methods: Performance of the code and the impact of various effects on the retrieved field distribution is tested first on the realistic magneto-hydrodynamic (MHD) simulations. The best inversion scenario is then applied to the real data obtained by Spectropolarimeter (SP) on board Hinode. Results: Tests on simulations show that: (1) the best choice of node position ensures a decent retrieval of all parameters; (2) the code performs well for different configurations of magnetic field; (3) slightly different noise levels or slightly different defocus included in the spatial point spread function (PSF) produces no significant effect on the results; and (4) temporal integration shifts the field distribution to a stronger, more horizontally inclined field. Conclusions: Although the contribution of the weak field is slightly overestimated owing to noise, 2D inversions are able to recover well the overall distribution of the magnetic field strength. Application of the 2D inversion code on the Hinode SP internetwork observations reveals a monotonic field strength distribution. The mean field strength at optical depth unity is ~ 130 G. At higher layers, field strength drops as the field becomes more horizontal. Regarding the distribution of the field inclination, tests show that we cannot directly retrieve it with the observations and tools at hand, however, the obtained distributions are consistent with those expected from simulations with a quasi-isotropic field inclination after accounting for observational effects.
Strain-induced Fermi contour anisotropy of GaAs (311)A 2D holes
NASA Astrophysics Data System (ADS)
Shabani, Javad; Shayegan, Mansour; Winkler, Roland
2008-03-01
There is considerable current interest in electronic properties of two-dimensional (2D) carriers whose energy bands are spin-split at finite values of in-plane wave vector, thanks to the spin-orbit interaction and the lack of inversion symmetry. We report experimental and theoretical results revealing that the spin-subband Fermi contours of the heavy and light heavy-holes (HHh and HHl) can be tuned in high mobility GaAs (311)A 2D hole systems via the application of symmetry-breaking in-plane strain. Our calculations show that the HHl spin-subband Fermi contour is circular but the HHh spin-subband Fermi contour is distorted. Experimentally, we probe the Fermi contour anisotropy by measuring the magneto-resistance commensurability peaks induced by square arrays of antidots. When the spin splitting is sufficiently large, the magneto-resistance trace exhibits two peaks, providing clear evidence for spin-resolved ballistic transport. The experimental results are in good agreement with the calculations, and confirm that the majority spin-subband (HHh) has a severely distorted Fermi contour whose anisotropy can be tuned with strain while Fermi contour of the minority spin-subband (HHl) remains nearly isotropic.
Mechanical characterization of 2D, 2D stitched, and 3D braided/RTM materials
NASA Technical Reports Server (NTRS)
Deaton, Jerry W.; Kullerd, Susan M.; Portanova, Marc A.
1993-01-01
Braided composite materials have potential for application in aircraft structures. Fuselage frames, floor beams, wing spars, and stiffeners are examples where braided composites could find application if cost effective processing and damage tolerance requirements are met. Another important consideration for braided composites relates to their mechanical properties and how they compare to the properties of composites produced by other textile composite processes being proposed for these applications. Unfortunately, mechanical property data for braided composites do not appear extensively in the literature. Data are presented in this paper on the mechanical characterization of 2D triaxial braid, 2D triaxial braid plus stitching, and 3D (through-the-thickness) braid composite materials. The braided preforms all had the same graphite tow size and the same nominal braid architectures, (+/- 30 deg/0 deg), and were resin transfer molded (RTM) using the same mold for each of two different resin systems. Static data are presented for notched and unnotched tension, notched and unnotched compression, and compression after impact strengths at room temperature. In addition, some static results, after environmental conditioning, are included. Baseline tension and compression fatigue results are also presented, but only for the 3D braided composite material with one of the resin systems.
NASA Astrophysics Data System (ADS)
Gough, D.
1984-12-01
Helioseismological inversion, as with the inversion of any other data, is divided into three phases. The first is the solution of the so-called forward problem: namely, the calculation of the eigenfrequencies of a theoretical equilibrium state. The second is an attempt to understand the results, either empirically by determining how those frequencies vary as chosen parameters defining the equilibrium model are varied, or analytically from asymptotic expansions in limiting cases of high order or degree. The third phase is to pose and solve an inverse problem, which seeks to find a plausible equilibrium model of the Sun whose eigenfrequencies are consistent with observation. The three phases are briefly discussed in this review, and the third, which is not yet widely used in helioseismology, is illustrated with some selected inversions of artificial solar data.
Phase Engineering of 2D Tin Sulfides.
Mutlu, Zafer; Wu, Ryan J; Wickramaratne, Darshana; Shahrezaei, Sina; Liu, Chueh; Temiz, Selcuk; Patalano, Andrew; Ozkan, Mihrimah; Lake, Roger K; Mkhoyan, K A; Ozkan, Cengiz S
2016-06-01
Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations. PMID:27099950
Phase Engineering of 2D Tin Sulfides.
Mutlu, Zafer; Wu, Ryan J; Wickramaratne, Darshana; Shahrezaei, Sina; Liu, Chueh; Temiz, Selcuk; Patalano, Andrew; Ozkan, Mihrimah; Lake, Roger K; Mkhoyan, K A; Ozkan, Cengiz S
2016-06-01
Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations.
NASA Astrophysics Data System (ADS)
Sergienko, Olga
2013-04-01
Since Doug MacAyeal's pioneering studies of the ice-stream basal traction optimizations by control methods, inversions for unknown parameters (e.g., basal traction, accumulation patterns, etc) have become a hallmark of the present-day ice-sheet modeling. The common feature of such inversion exercises is a direct relationship between optimized parameters and observations used in the optimization procedure. For instance, in the standard optimization for basal traction by the control method, ice-stream surface velocities constitute the control data. The optimized basal traction parameters explicitly appear in the momentum equations for the ice-stream velocities (compared to the control data). The inversion for basal traction is carried out by minimization of the cost (or objective, misfit) function that includes the momentum equations facilitated by the Lagrange multipliers. Here, we build upon this idea, and demonstrate how to optimize for parameters indirectly related to observed data using a suite of nested constraints (like Russian dolls) with additional sets of Lagrange multipliers in the cost function. This method opens the opportunity to use data from a variety of sources and types (e.g., velocities, radar layers, surface elevation changes, etc.) in the same optimization process.
A Bayesian approach to modeling 2D gravity data using polygon states
NASA Astrophysics Data System (ADS)
Titus, W. J.; Titus, S.; Davis, J. R.
2015-12-01
We present a Bayesian Markov chain Monte Carlo (MCMC) method for the 2D gravity inversion of a localized subsurface object with constant density contrast. Our models have four parameters: the density contrast, the number of vertices in a polygonal approximation of the object, an upper bound on the ratio of the perimeter squared to the area, and the vertices of a polygon container that bounds the object. Reasonable parameter values can be estimated prior to inversion using a forward model and geologic information. In addition, we assume that the field data have a common random uncertainty that lies between two bounds but that it has no systematic uncertainty. Finally, we assume that there is no uncertainty in the spatial locations of the measurement stations. For any set of model parameters, we use MCMC methods to generate an approximate probability distribution of polygons for the object. We then compute various probability distributions for the object, including the variance between the observed and predicted fields (an important quantity in the MCMC method), the area, the center of area, and the occupancy probability (the probability that a spatial point lies within the object). In addition, we compare probabilities of different models using parallel tempering, a technique which also mitigates trapping in local optima that can occur in certain model geometries. We apply our method to several synthetic data sets generated from objects of varying shape and location. We also analyze a natural data set collected across the Rio Grande Gorge Bridge in New Mexico, where the object (i.e. the air below the bridge) is known and the canyon is approximately 2D. Although there are many ways to view results, the occupancy probability proves quite powerful. We also find that the choice of the container is important. In particular, large containers should be avoided, because the more closely a container confines the object, the better the predictions match properties of object.
NASA Technical Reports Server (NTRS)
Miller, Christopher J.
2011-01-01
A model reference nonlinear dynamic inversion control law has been developed to provide a baseline controller for research into simple adaptive elements for advanced flight control laws. This controller has been implemented and tested in a hardware-in-the-loop simulation and in flight. The flight results agree well with the simulation predictions and show good handling qualities throughout the tested flight envelope with some noteworthy deficiencies highlighted both by handling qualities metrics and pilot comments. Many design choices and implementation details reflect the requirements placed on the system by the nonlinear flight environment and the desire to keep the system as simple as possible to easily allow the addition of the adaptive elements. The flight-test results and how they compare to the simulation predictions are discussed, along with a discussion about how each element affected pilot opinions. Additionally, aspects of the design that performed better than expected are presented, as well as some simple improvements that will be suggested for follow-on work.
Brancaccio, R; Bettuzzi, M; Morigi, M P; Casali, F; Levi, G; Baldazzi, G; Inferrera, P
2016-09-01
Dynamic AngioThermography (DATG) is a contact-plate technique capable of producing a digital representation of breast vascularity. The inception and growth of a tumor are associated with neoangenesis, which may result in a demonstrable alteration in the regional blood flow, while in normal health conditions the vascularity remains unchanged throughout life. DATG, if included in the clinical evaluation for breast cancer, could potentially improve the accuracy of the diagnosis of this disease. Conventional DATG is limited, however, in that it is a projection (i.e. two-dimensional) imaging technique that does not provide any information on the depth and its effect on the pattern of the perfusion revealed by this technique. In fact, the blood pattern is detected by projecting temperature signals on the plate, thus acquiring a digital two-dimensional image. In this article we propose a new approach for extracting information on depth through the inversion of the Fourier heat equation. The idea is to extract the information along the third axis while acquiring and analyzing the temporal sequence during the process of image formation. The method implemented has been tested on a dedicated "electric phantom" and in one in vivo experiment. In spite of the limits of these preliminary tests, the experimental results have shown that this method makes it possible to obtain a 3D representation of the vascularity. Although it appears to be promising, further validation and characterization of our technique are required. PMID:27618585
Brancaccio, R; Bettuzzi, M; Morigi, M P; Casali, F; Levi, G; Baldazzi, G; Inferrera, P
2016-09-01
Dynamic AngioThermography (DATG) is a contact-plate technique capable of producing a digital representation of breast vascularity. The inception and growth of a tumor are associated with neoangenesis, which may result in a demonstrable alteration in the regional blood flow, while in normal health conditions the vascularity remains unchanged throughout life. DATG, if included in the clinical evaluation for breast cancer, could potentially improve the accuracy of the diagnosis of this disease. Conventional DATG is limited, however, in that it is a projection (i.e. two-dimensional) imaging technique that does not provide any information on the depth and its effect on the pattern of the perfusion revealed by this technique. In fact, the blood pattern is detected by projecting temperature signals on the plate, thus acquiring a digital two-dimensional image. In this article we propose a new approach for extracting information on depth through the inversion of the Fourier heat equation. The idea is to extract the information along the third axis while acquiring and analyzing the temporal sequence during the process of image formation. The method implemented has been tested on a dedicated "electric phantom" and in one in vivo experiment. In spite of the limits of these preliminary tests, the experimental results have shown that this method makes it possible to obtain a 3D representation of the vascularity. Although it appears to be promising, further validation and characterization of our technique are required.
2D:4D asymmetry and gender differences in academic performance.
Nye, John V C; Androuschak, Gregory; Desierto, Desirée; Jones, Garett; Yudkevich, Maria
2012-01-01
Exposure to prenatal androgens affects both future behavior and life choices. However, there is still relatively limited evidence on its effects on academic performance. Moreover, the predicted effect of exposure to prenatal testosterone (T)-which is inversely correlated with the relative length of the second to fourth finger lengths (2D:4D)-would seem to have ambiguous effects on academic achievement since traits like aggressiveness or risk-taking are not uniformly positive for success in school. We provide the first evidence of a non-linear, quadratic, relationship between 2D:4D and academic achievement using samples from Moscow and Manila. We also find that there is a gender differentiated link between various measures of academic achievement and measured digit ratios. These effects are different depending on the field of study, choice of achievement measure, and use of the right hand or left digit ratios. The results seem to be asymmetric between Moscow and Manila where the right (left) hand generates inverted-U (U-shaped) curves in Moscow while the pattern for hands reverses in Manila. Drawing from unusually large and detailed samples of university students in two countries not studied in the digit literature, our work is the first to have a large cross country comparison that includes two groups with very different ethnic compositions.
Calculating tissue shear modulus and pressure by 2D Log-Elastographic methods
McLaughlin, Joyce R; Zhang, Ning; Manduca, Armando
2010-01-01
Shear modulus imaging, often called elastography, enables detection and characterization of tissue abnormalities. In this paper the data is two displacement components obtained from successive MR or ultrasound data sets acquired while the tissue is excited mechanically. A 2D plane strain elastic model is assumed to govern the 2D displacement, u. The shear modulus, μ, is unknown and whether or not the first Lamé parameter, λ, is known the pressure p = λ∇ · u which is present in the plane strain model cannot be measured and is unreliably computed from measured data and can be shown to be an order one quantity in the units kPa. So here we present a 2D Log-Elastographic inverse algorithm that: (1) simultaneously reconstructs the shear modulus, μ, and p, which together satisfy a first order partial differential equation system, with the goal of imaging μ; (2) controls potential exponential growth in the numerical error; and (3) reliably reconstructs the quantity p in the inverse algorithm as compared to the same quantity computed with a forward algorithm. This work generalizes the Log-Elastographic algorithm in [20] which uses one displacement component, is derived assuming the component satisfies the wave equation, and is tested on synthetic data computed with the wave equation model. The 2D Log-Elastographic algorithm is tested on 2D synthetic data and 2D in-vivo data from Mayo Clinic. We also exhibit examples to show that the 2D Log-Elastographic algorithm improves the quality of the recovered images as compared to the Log-Elastographic and Direct Inversion algorithms. PMID:21822349
Orthotropic Piezoelectricity in 2D Nanocellulose
NASA Astrophysics Data System (ADS)
García, Y.; Ruiz-Blanco, Yasser B.; Marrero-Ponce, Yovani; Sotomayor-Torres, C. M.
2016-10-01
The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V‑1, ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies.
Orthotropic Piezoelectricity in 2D Nanocellulose
García, Y.; Ruiz-Blanco, Yasser B.; Marrero-Ponce, Yovani; Sotomayor-Torres, C. M.
2016-01-01
The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V−1, ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies. PMID:27708364
2D microwave imaging reflectometer electronics
Spear, A. G.; Domier, C. W. Hu, X.; Muscatello, C. M.; Ren, X.; Luhmann, N. C.; Tobias, B. J.
2014-11-15
A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.
Optical modulators with 2D layered materials
NASA Astrophysics Data System (ADS)
Sun, Zhipei; Martinez, Amos; Wang, Feng
2016-04-01
Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that 2D layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this Review, we cover the state of the art of optical modulators based on 2D materials, including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as 2D heterostructures, plasmonic structures, and silicon and fibre integrated structures. We also take a look at the future perspectives and discuss the potential of yet relatively unexplored mechanisms, such as magneto-optic and acousto-optic modulation.
Experimental identification of diffusive coupling using 2D NMR.
Song, Y-Q; Carneiro, G; Schwartz, L M; Johnson, D L
2014-12-01
Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique. PMID:25526135
The inverse electroencephalography pipeline
NASA Astrophysics Data System (ADS)
Weinstein, David Michael
The inverse electroencephalography (EEG) problem is defined as determining which regions of the brain are active based on remote measurements recorded with scalp EEG electrodes. An accurate solution to this problem would benefit both fundamental neuroscience research and clinical neuroscience applications. However, constructing accurate patient-specific inverse EEG solutions requires complex modeling, simulation, and visualization algorithms, and to date only a few systems have been developed that provide such capabilities. In this dissertation, a computational system for generating and investigating patient-specific inverse EEG solutions is introduced, and the requirements for each stage of this Inverse EEG Pipeline are defined and discussed. While the requirements of many of the stages are satisfied with existing algorithms, others have motivated research into novel modeling and simulation methods. The principal technical results of this work include novel surface-based volume modeling techniques, an efficient construction for the EEG lead field, and the Open Source release of the Inverse EEG Pipeline software for use by the bioelectric field research community. In this work, the Inverse EEG Pipeline is applied to three research problems in neurology: comparing focal and distributed source imaging algorithms; separating measurements into independent activation components for multifocal epilepsy; and localizing the cortical activity that produces the P300 effect in schizophrenia.
Mean flow and anisotropic cascades in decaying 2D turbulence
NASA Astrophysics Data System (ADS)
Liu, Chien-Chia; Cerbus, Rory; Gioia, Gustavo; Chakraborty, Pinaki
2015-11-01
Many large-scale atmospheric and oceanic flows are decaying 2D turbulent flows embedded in a non-uniform mean flow. Despite its importance for large-scale weather systems, the affect of non-uniform mean flows on decaying 2D turbulence remains unknown. In the absence of mean flow it is well known that decaying 2D turbulent flows exhibit the enstrophy cascade. More generally, for any 2D turbulent flow, all computational, experimental and field data amassed to date indicate that the spectrum of longitudinal and transverse velocity fluctuations correspond to the same cascade, signifying isotropy of cascades. Here we report experiments on decaying 2D turbulence in soap films with a non-uniform mean flow. We find that the flow transitions from the usual isotropic enstrophy cascade to a series of unusual and, to our knowledge, never before observed or predicted, anisotropic cascades where the longitudinal and transverse spectra are mutually independent. We discuss implications of our results for decaying geophysical turbulence.
Inkjet printing of 2D layered materials.
Li, Jiantong; Lemme, Max C; Östling, Mikael
2014-11-10
Inkjet printing of 2D layered materials, such as graphene and MoS2, has attracted great interests for emerging electronics. However, incompatible rheology, low concentration, severe aggregation and toxicity of solvents constitute critical challenges which hamper the manufacturing efficiency and product quality. Here, we introduce a simple and general technology concept (distillation-assisted solvent exchange) to efficiently overcome these challenges. By implementing the concept, we have demonstrated excellent jetting performance, ideal printing patterns and a variety of promising applications for inkjet printing of 2D layered materials. PMID:25169938
Inkjet printing of 2D layered materials.
Li, Jiantong; Lemme, Max C; Östling, Mikael
2014-11-10
Inkjet printing of 2D layered materials, such as graphene and MoS2, has attracted great interests for emerging electronics. However, incompatible rheology, low concentration, severe aggregation and toxicity of solvents constitute critical challenges which hamper the manufacturing efficiency and product quality. Here, we introduce a simple and general technology concept (distillation-assisted solvent exchange) to efficiently overcome these challenges. By implementing the concept, we have demonstrated excellent jetting performance, ideal printing patterns and a variety of promising applications for inkjet printing of 2D layered materials.
Ffrench, P A; Zeidler, J H; Ku, W H
1997-01-01
Two-dimensional (2-D) adaptive filtering is a technique that can be applied to many image processing applications. This paper will focus on the development of an improved 2-D adaptive lattice algorithm (2-D AL) and its application to the removal of correlated clutter to enhance the detectability of small objects in images. The two improvements proposed here are increased flexibility in the calculation of the reflection coefficients and a 2-D method to update the correlations used in the 2-D AL algorithm. The 2-D AL algorithm is shown to predict correlated clutter in image data and the resulting filter is compared with an ideal Wiener-Hopf filter. The results of the clutter removal will be compared to previously published ones for a 2-D least mean square (LMS) algorithm. 2-D AL is better able to predict spatially varying clutter than the 2-D LMS algorithm, since it converges faster to new image properties. Examples of these improvements are shown for a spatially varying 2-D sinusoid in white noise and simulated clouds. The 2-D LMS and 2-D AL algorithms are also shown to enhance a mammogram image for the detection of small microcalcifications and stellate lesions.
Zimmerman, D.A.; Gallegos, D.P.
1993-10-01
The groundwater flow pathway in the Culebra Dolomite aquifer at the Waste Isolation Pilot Plant (WIPP) has been identified as a potentially important pathway for radionuclide migration to the accessible environment. Consequently, uncertainties in the models used to describe flow and transport in the Culebra need to be addressed. A ``Geostatistics Test Problem`` is being developed to evaluate a number of inverse techniques that may be used for flow calculations in the WIPP performance assessment (PA). The Test Problem is actually a series of test cases, each being developed as a highly complex synthetic data set; the intent is for the ensemble of these data sets to span the range of possible conceptual models of groundwater flow at the WIPP site. The Test Problem analysis approach is to use a comparison of the probabilistic groundwater travel time (GWTT) estimates produced by each technique as the basis for the evaluation. Participants are given observations of head and transmissivity (possibly including measurement error) or other information such as drawdowns from pumping wells, and are asked to develop stochastic models of groundwater flow for the synthetic system. Cumulative distribution functions (CDFs) of groundwater flow (computed via particle tracking) are constructed using the head and transmissivity data generated through the application of each technique; one semi-analytical method generates the CDFs of groundwater flow directly. This paper describes the results from Test Case No. 1.
NASA Astrophysics Data System (ADS)
Mishin, V. V.; Mishin, V. M.; Karavaev, Yu.; Han, J. P.; Wang, C.
2016-07-01
We report on novel features of the saturation process of the polar cap magnetic flux and Poynting flux into the magnetosphere from the solar wind during three superstorms. In addition to the well-known effect of the interplanetary electric (Esw) and southward magnetic (interplanetary magnetic field (IMF) Bz) fields, we found that the saturation depends also on the solar wind ram pressure Pd. By means of the magnetogram inversion technique and a global MHD numerical model Piecewise Parabolic Method with a Lagrangian Remap, we explore the dependence of the magnetopause standoff distance on ram pressure and the southward IMF. Unlike earlier studies, in the considered superstorms both Pd and Bz achieve extreme values. As a result, we show that the compression rate of the dayside magnetosphere decreases with increasing Pd and the southward Bz, approaching very small values for extreme Pd ≥ 15 nPa and Bz ≤ -40 nT. This dependence suggests that finite compressibility of the magnetosphere controls saturation of superstorms.
2d PDE Linear Symmetric Matrix Solver
1983-10-01
ICCG2 (Incomplete Cholesky factorized Conjugate Gradient algorithm for 2d symmetric problems) was developed to solve a linear symmetric matrix system arising from a 9-point discretization of two-dimensional elliptic and parabolic partial differential equations found in plasma physics applications, such as resistive MHD, spatial diffusive transport, and phase space transport (Fokker-Planck equation) problems. These problems share the common feature of being stiff and requiring implicit solution techniques. When these parabolic or elliptic PDE''s are discretized withmore » finite-difference or finite-element methods,the resulting matrix system is frequently of block-tridiagonal form. To use ICCG2, the discretization of the two-dimensional partial differential equation and its boundary conditions must result in a block-tridiagonal supermatrix composed of elementary tridiagonal matrices. The incomplete Cholesky conjugate gradient algorithm is used to solve the linear symmetric matrix equation. Loops are arranged to vectorize on the Cray1 with the CFT compiler, wherever possible. Recursive loops, which cannot be vectorized, are written for optimum scalar speed. For matrices lacking symmetry, ILUCG2 should be used. Similar methods in three dimensions are available in ICCG3 and ILUCG3. A general source containing extensions and macros, which must be processed by a pre-compiler to obtain the standard FORTRAN source, is provided along with the standard FORTRAN source because it is believed to be more readable. The pre-compiler is not included, but pre-compilation may be performed by a text editor as described in the UCRL-88746 Preprint.« less
2d PDE Linear Asymmetric Matrix Solver
1983-10-01
ILUCG2 (Incomplete LU factorized Conjugate Gradient algorithm for 2d problems) was developed to solve a linear asymmetric matrix system arising from a 9-point discretization of two-dimensional elliptic and parabolic partial differential equations found in plasma physics applications, such as plasma diffusion, equilibria, and phase space transport (Fokker-Planck equation) problems. These equations share the common feature of being stiff and requiring implicit solution techniques. When these parabolic or elliptic PDE''s are discretized with finite-difference or finite-elementmore » methods, the resulting matrix system is frequently of block-tridiagonal form. To use ILUCG2, the discretization of the two-dimensional partial differential equation and its boundary conditions must result in a block-tridiagonal supermatrix composed of elementary tridiagonal matrices. A generalization of the incomplete Cholesky conjugate gradient algorithm is used to solve the matrix equation. Loops are arranged to vectorize on the Cray1 with the CFT compiler, wherever possible. Recursive loops, which cannot be vectorized, are written for optimum scalar speed. For problems having a symmetric matrix ICCG2 should be used since it runs up to four times faster and uses approximately 30% less storage. Similar methods in three dimensions are available in ICCG3 and ILUCG3. A general source, containing extensions and macros, which must be processed by a pre-compiler to obtain the standard FORTRAN source, is provided along with the standard FORTRAN source because it is believed to be more readable. The pre-compiler is not included, but pre-compilation may be performed by a text editor as described in the UCRL-88746 Preprint.« less
Spin splitting in 2D monochalcogenide semiconductors
Do, Dat T.; Mahanti, Subhendra D.; Lai, Chih Wei
2015-01-01
We report ab initio calculations of the spin splitting of the uppermost valence band (UVB) and the lowermost conduction band (LCB) in bulk and atomically thin GaS, GaSe, GaTe, and InSe. These layered monochalcogenides appear in four major polytypes depending on the stacking order, except for the monoclinic GaTe. Bulk and few-layer ε-and γ -type, and odd-number β-type GaS, GaSe, and InSe crystals are noncentrosymmetric. The spin splittings of the UVB and the LCB near the Γ-point in the Brillouin zone are finite, but still smaller than those in a zinc-blende semiconductor such as GaAs. On the other hand, the spin splitting is zero in centrosymmetric bulk and even-number few-layer β-type GaS, GaSe, and InSe, owing to the constraint of spatial inversion symmetry. By contrast, GaTe exhibits zero spin splitting because it is centrosymmetric down to a single layer. In these monochalcogenide semiconductors, the separation of the non-degenerate conduction and valence bands from adjacent bands results in the suppression of Elliot-Yafet spin relaxation mechanism. Therefore, the electron- and hole-spin relaxation times in these systems with zero or minimal spin splittings are expected to exceed those in GaAs when the D’yakonov-Perel’ spin relaxation mechanism is also suppressed. PMID:26596907
Design of the LRP airfoil series using 2D CFD
NASA Astrophysics Data System (ADS)
Zahle, Frederik; Bak, Christian; Sørensen, Niels N.; Vronsky, Tomas; Gaudern, Nicholas
2014-06-01
This paper describes the design and wind tunnel testing of a high-Reynolds number, high lift airfoil series designed for wind turbines. The airfoils were designed using direct gradient- based numerical multi-point optimization based on a Bezier parameterization of the shape, coupled to the 2D Navier-Stokes flow solver EllipSys2D. The resulting airfoils, the LRP2-30 and LRP2-36, achieve both higher operational lift coefficients and higher lift to drag ratios compared to the equivalent FFA-W3 airfoils.
Finite temperature corrections in 2d integrable models
NASA Astrophysics Data System (ADS)
Caselle, M.; Hasenbusch, M.
2002-09-01
We study the finite size corrections for the magnetization and the internal energy of the 2d Ising model in a magnetic field by using transfer matrix techniques. We compare these corrections with the functional form recently proposed by Delfino and LeClair-Mussardo for the finite temperature behaviour of one-point functions in integrable 2d quantum field theories. We find a perfect agreement between theoretical expectations and numerical results. Assuming the proposed functional form as an input in our analysis we obtain a relevant improvement in the precision of the continuum limit estimates of both quantities.
Parallel stitching of 2D materials
Ling, Xi; Wu, Lijun; Lin, Yuxuan; Ma, Qiong; Wang, Ziqiang; Song, Yi; Yu, Lili; Huang, Shengxi; Fang, Wenjing; Zhang, Xu; et al
2016-01-27
Diverse parallel stitched 2D heterostructures, including metal–semiconductor, semiconductor–semiconductor, and insulator–semiconductor, are synthesized directly through selective “sowing” of aromatic molecules as the seeds in the chemical vapor deposition (CVD) method. Lastly, the methodology enables the large-scale fabrication of lateral heterostructures, which offers tremendous potential for its application in integrated circuits.
Parallel Stitching of 2D Materials.
Ling, Xi; Lin, Yuxuan; Ma, Qiong; Wang, Ziqiang; Song, Yi; Yu, Lili; Huang, Shengxi; Fang, Wenjing; Zhang, Xu; Hsu, Allen L; Bie, Yaqing; Lee, Yi-Hsien; Zhu, Yimei; Wu, Lijun; Li, Ju; Jarillo-Herrero, Pablo; Dresselhaus, Mildred; Palacios, Tomás; Kong, Jing
2016-03-23
Diverse parallel stitched 2D heterostructures, including metal-semiconductor, semiconductor-semiconductor, and insulator-semiconductor, are synthesized directly through selective "sowing" of aromatic molecules as the seeds in the chemical vapor deposition (CVD) method. The methodology enables the large-scale fabrication of lateral heterostructures, which offers tremendous potential for its application in integrated circuits.
Laboratory Experiments On Continually Forced 2d Turbulence
NASA Astrophysics Data System (ADS)
Wells, M. G.; Clercx, H. J. H.; Van Heijst, G. J. F.
There has been much recent interest in the advection of tracers by 2D turbulence in geophysical flows. While there is a large body of literature on decaying 2D turbulence or forced 2D turbulence in unbounded domains, there have been very few studies of forced turbulence in bounded domains. In this study we present new experimental results from a continuously forced quasi 2D turbulent field. The experiments are performed in a square Perspex tank filled with water. The flow is made quasi 2D by a steady background rotation. The rotation rate of the tank has a small (<8 %) sinusoidal perturbation which leads to the periodic formation of eddies in the corners of the tank. When the oscillation period of the perturbation is greater than an eddy roll-up time-scale, dipole structures are observed to form. The dipoles can migrate away from the walls, and the interior of the tank is continually filled with vortexs. From experimental visualizations the length scale of the vortexs appears to be largely controlled by the initial formation mechanism and large scale structures are not observed to form at large times. Thus the experiments provide a simple way of cre- ating a continuously forced 2D turbulent field. The resulting structures are in contrast with most previous laboratory experiments on 2D turbulence which have investigated decaying turbulence and have observed the formations of large scale structure. In these experiments, decaying turbulence had been produced by a variety of methods such as the decaying turbulence in the wake of a comb of rods (Massen et al 1999), organiza- tion of vortices in thin conducting liquids (Cardoso et al 1994) or in rotating systems where there are sudden changes in angular rotation rate (Konijnenberg et al 1998). Results of dye visualizations, particle tracking experiments and a direct numerical simulation will be presented and discussed in terms of their oceanographic application. Bibliography Cardoso,O. Marteau, D. &Tabeling, P
NASA Astrophysics Data System (ADS)
Garcia Juanatey, M. A.; Hübert, J.; Tryggvason, A.; Juhlin, C.; Pedersen, L. B.; Bauer, T. E.; Dehghannejad, M.
2012-12-01
Broadband MT data were acquired in the Skellefte district, an important mining area in northern Sweden, as part of the VINNOVA project "4D modeling of the Skellefte District". The project aims to provide a better understanding of the local and regional processes that took place in the past and, thus, provide a framework for new exploration strategies to target deeper deposits in the area. The new MT data, acquired in the central part of the district, consist of 36 stations along two parallel profiles that follow seismic reflection lines and potential field modeling studies in the area. The dimensionality and quality of the data set were carefully analyzed and 2D and 3D inversions were performed. 2D inversions provided a basis to compare with other MT surveys in the area and to some extent validate 3D inversion results. 3D inversion was deemed necessary given the complexity of the geological setting of the studied area. The algorithms used were the data space based REBOCC and WSINV3DMT methods. For the 2D inversion only the determinant of the impedance tensor was used, while for the 3D inversion all its elements were considered. Prior to 3D inversion, new error floors were calculated using individual 1D inversions of the off-diagonal components of the impedance tensor. The obtained models have an RMS value of ~2, and share the main regional features. A detailed comparison reveals the superiority of the 3D model, both in model structures and data fit. An interpretation of the 3D model is presented using also results from previous geophysical studies. The most interesting features in the model are conductors associated to prominent shear zones (from 1 to 12 km deep) and hydrothermally altered zones within the Skellefte Group rocks (between 250 and 6000 m depth). In addition, it is possible to identify faults associated to the transport of hydrothermal fluids that might be closely related to ore forming processes.
Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology
Shavanova, Kateryna; Bakakina, Yulia; Burkova, Inna; Shtepliuk, Ivan; Viter, Roman; Ubelis, Arnolds; Beni, Valerio; Starodub, Nickolaj; Yakimova, Rositsa; Khranovskyy, Volodymyr
2016-01-01
The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct “beyond graphene” domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical). A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials. PMID:26861346
Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology.
Shavanova, Kateryna; Bakakina, Yulia; Burkova, Inna; Shtepliuk, Ivan; Viter, Roman; Ubelis, Arnolds; Beni, Valerio; Starodub, Nickolaj; Yakimova, Rositsa; Khranovskyy, Volodymyr
2016-01-01
The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct "beyond graphene" domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical). A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials.
Hartzell, S.
1989-01-01
The July 8, 1986, North Palm Strings earthquake is used as a basis for comparison of several different approaches to the solution for the rupture history of a finite fault. The inversion of different waveform data is considered; both teleseismic P waveforms and local strong ground motion records. Linear parametrizations for slip amplitude are compared with nonlinear parametrizations for both slip amplitude and rupture time. Inversions using both synthetic and empirical Green's functions are considered. In general, accurate Green's functions are more readily calculable for the teleseismic problem where simple ray theory and flat-layered velocity structures are usually sufficient. However, uncertainties in the variation in t* with frequency most limit the resolution of teleseismic inversions. A set of empirical Green's functions that are well recorded at teleseismic distances could avoid the uncertainties in attenuation. In the inversion of strong motion data, the accurate calculation of propagation path effects other than attenuation effects is the limiting factor in the resolution of source parameters. -from Author
NASA Astrophysics Data System (ADS)
Trofimov, Vyacheslav A.; Egorenkov, Vladimir A.; Loginova, Mariya M.
2015-08-01
We analyze laser-induced periodic structure developing in a semiconductor under the condition of both optical bistability existence and action of 2D external electric field. Optical bistability occurs because of nonlinear dependence of semiconductor absorption coefficient on charged particles concentration. The electron mobility, diffusion of electrons and laser-induced electric field are taken into account for laser pulse propagation analyzing. 2D external electric field together with electric field, induced by free electrons and ionized donors, governs the charged particle motion. Under certain conditions, the additional positive inverse loop between electron motion and electric field, caused by redistribution of free charged particles, appears. As a result, the helical wave for free charged particle concentration of electron-hole plasma in semiconductor develops under the electric field action. For computer simulation of a problem under consideration, a new finite-difference scheme is proposed. The main feature of proposed method consists in constructed two-step iteration process. We pay a special attention for calculation of initial functions distributions. For their calculation we solve the set of 2D stationary partial differential equations by using additional iteration process that is similar to the iteration process, applied for the main problem solution.
Correlated Electron Phenomena in 2D Materials
NASA Astrophysics Data System (ADS)
Lambert, Joseph G.
In this thesis, I present experimental results on coherent electron phenomena in layered two-dimensional materials: single layer graphene and van der Waals coupled 2D TiSe2. Graphene is a two-dimensional single-atom thick sheet of carbon atoms first derived from bulk graphite by the mechanical exfoliation technique in 2004. Low-energy charge carriers in graphene behave like massless Dirac fermions, and their density can be easily tuned between electron-rich and hole-rich quasiparticles with electrostatic gating techniques. The sharp interfaces between regions of different carrier densities form barriers with selective transmission, making them behave as partially reflecting mirrors. When two of these interfaces are set at a separation distance within the phase coherence length of the carriers, they form an electronic version of a Fabry-Perot cavity. I present measurements and analysis of multiple Fabry-Perot modes in graphene with parallel electrodes spaced a few hundred nanometers apart. Transition metal dichalcogenide (TMD) TiSe2 is part of the family of materials that coined the term "materials beyond graphene". It contains van der Waals coupled trilayer stacks of Se-Ti-Se. Many TMD materials exhibit a host of interesting correlated electronic phases. In particular, TiSe2 exhibits chiral charge density waves (CDW) below TCDW ˜ 200 K. Upon doping with copper, the CDW state gets suppressed with Cu concentration, and CuxTiSe2 becomes superconducting with critical temperature of T c = 4.15 K. There is still much debate over the mechanisms governing the coexistence of the two correlated electronic phases---CDW and superconductivity. I will present some of the first conductance spectroscopy measurements of proximity coupled superconductor-CDW systems. Measurements reveal a proximity-induced critical current at the Nb-TiSe2 interfaces, suggesting pair correlations in the pure TiSe2. The results indicate that superconducting order is present concurrently with CDW in
Explicit 2-D Hydrodynamic FEM Program
1996-08-07
DYNA2D* is a vectorized, explicit, two-dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D* contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic/isotropic elastic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, rubber, high explosive burn, isotropic elastic-plastic, temperature-dependent elastic-plastic. Themore » isotropic and temperature-dependent elastic-plastic models determine only the deviatoric stresses. Pressure is determined by one of 9 equations of state including linear polynomial, JWL high explosive, Sack Tuesday high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, and tabulated.« less
Static & Dynamic Response of 2D Solids
1996-07-15
NIKE2D is an implicit finite-element code for analyzing the finite deformation, static and dynamic response of two-dimensional, axisymmetric, plane strain, and plane stress solids. The code is fully vectorized and available on several computing platforms. A number of material models are incorporated to simulate a wide range of material behavior including elasto-placicity, anisotropy, creep, thermal effects, and rate dependence. Slideline algorithms model gaps and sliding along material interfaces, including interface friction, penetration and single surfacemore » contact. Interactive-graphics and rezoning is included for analyses with large mesh distortions. In addition to quasi-Newton and arc-length procedures, adaptive algorithms can be defined to solve the implicit equations using the solution language ISLAND. Each of these capabilities and more make NIKE2D a robust analysis tool.« less
Static & Dynamic Response of 2D Solids
Lin, Jerry
1996-07-15
NIKE2D is an implicit finite-element code for analyzing the finite deformation, static and dynamic response of two-dimensional, axisymmetric, plane strain, and plane stress solids. The code is fully vectorized and available on several computing platforms. A number of material models are incorporated to simulate a wide range of material behavior including elasto-placicity, anisotropy, creep, thermal effects, and rate dependence. Slideline algorithms model gaps and sliding along material interfaces, including interface friction, penetration and single surface contact. Interactive-graphics and rezoning is included for analyses with large mesh distortions. In addition to quasi-Newton and arc-length procedures, adaptive algorithms can be defined to solve the implicit equations using the solution language ISLAND. Each of these capabilities and more make NIKE2D a robust analysis tool.
Explicit 2-D Hydrodynamic FEM Program
Lin, Jerry
1996-08-07
DYNA2D* is a vectorized, explicit, two-dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D* contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic/isotropic elastic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, rubber, high explosive burn, isotropic elastic-plastic, temperature-dependent elastic-plastic. The isotropic and temperature-dependent elastic-plastic models determine only the deviatoric stresses. Pressure is determined by one of 9 equations of state including linear polynomial, JWL high explosive, Sack Tuesday high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, and tabulated.
Strain-driven band inversion and topological aspects in Antimonene
Zhao, Mingwen; Zhang, Xiaoming; Li, Linyang
2015-01-01
Searching for the two-dimensional (2D) topological insulators (TIs) with large bulk band gaps is the key to achieve room-temperature quantum spin Hall effect (QSHE). Using first-principles calculations, we demonstrated that the recently-proposed antimonene [Zhang et al., Angew. Chem. Int. Ed. 54, 3112–3115 (2015)] can be tuned to a 2D TI by reducing the buckling height of the lattice which can be realized under tensile strain. The strain-driven band inversion in the vicinity of the Fermi level is responsible for the quantum phase transition. The buckled configuration of antimonene enables it to endure large tensile strain up to 18% and the resulted bulk band gap can be as large as 270 meV. The tunable bulk band gap makes antimonene a promising candidate material for achieving quantum spin Hall effect (QSH) at high temperatures which meets the requirement of future electronic devices with low power consumption. PMID:26537994
Strain-driven band inversion and topological aspects in Antimonene.
Zhao, Mingwen; Zhang, Xiaoming; Li, Linyang
2015-01-01
Searching for the two-dimensional (2D) topological insulators (TIs) with large bulk band gaps is the key to achieve room-temperature quantum spin Hall effect (QSHE). Using first-principles calculations, we demonstrated that the recently-proposed antimonene [Zhang et al., Angew. Chem. Int. Ed. 54, 3112-3115 (2015)] can be tuned to a 2D TI by reducing the buckling height of the lattice which can be realized under tensile strain. The strain-driven band inversion in the vicinity of the Fermi level is responsible for the quantum phase transition. The buckled configuration of antimonene enables it to endure large tensile strain up to 18% and the resulted bulk band gap can be as large as 270 meV. The tunable bulk band gap makes antimonene a promising candidate material for achieving quantum spin Hall effect (QSH) at high temperatures which meets the requirement of future electronic devices with low power consumption.
Compact 2-D graphical representation of DNA
NASA Astrophysics Data System (ADS)
Randić, Milan; Vračko, Marjan; Zupan, Jure; Novič, Marjana
2003-05-01
We present a novel 2-D graphical representation for DNA sequences which has an important advantage over the existing graphical representations of DNA in being very compact. It is based on: (1) use of binary labels for the four nucleic acid bases, and (2) use of the 'worm' curve as template on which binary codes are placed. The approach is illustrated on DNA sequences of the first exon of human β-globin and gorilla β-globin.
2D materials: Graphene and others
NASA Astrophysics Data System (ADS)
Bansal, Suneev Anil; Singh, Amrinder Pal; Kumar, Suresh
2016-05-01
Present report reviews the recent advancements in new atomically thick 2D materials. Materials covered in this review are Graphene, Silicene, Germanene, Boron Nitride (BN) and Transition metal chalcogenides (TMC). These materials show extraordinary mechanical, electronic and optical properties which make them suitable candidates for future applications. Apart from unique properties, tune-ability of highly desirable properties of these materials is also an important area to be emphasized on.
Layer Engineering of 2D Semiconductor Junctions.
He, Yongmin; Sobhani, Ali; Lei, Sidong; Zhang, Zhuhua; Gong, Yongji; Jin, Zehua; Zhou, Wu; Yang, Yingchao; Zhang, Yuan; Wang, Xifan; Yakobson, Boris; Vajtai, Robert; Halas, Naomi J; Li, Bo; Xie, Erqing; Ajayan, Pulickel
2016-07-01
A new concept for junction fabrication by connecting multiple regions with varying layer thicknesses, based on the thickness dependence, is demonstrated. This type of junction is only possible in super-thin-layered 2D materials, and exhibits similar characteristics as p-n junctions. Rectification and photovoltaic effects are observed in chemically homogeneous MoSe2 junctions between domains of different thicknesses. PMID:27136275
MAGNUM-2D computer code: user's guide
England, R.L.; Kline, N.W.; Ekblad, K.J.; Baca, R.G.
1985-01-01
Information relevant to the general use of the MAGNUM-2D computer code is presented. This computer code was developed for the purpose of modeling (i.e., simulating) the thermal and hydraulic conditions in the vicinity of a waste package emplaced in a deep geologic repository. The MAGNUM-2D computer computes (1) the temperature field surrounding the waste package as a function of the heat generation rate of the nuclear waste and thermal properties of the basalt and (2) the hydraulic head distribution and associated groundwater flow fields as a function of the temperature gradients and hydraulic properties of the basalt. MAGNUM-2D is a two-dimensional numerical model for transient or steady-state analysis of coupled heat transfer and groundwater flow in a fractured porous medium. The governing equations consist of a set of coupled, quasi-linear partial differential equations that are solved using a Galerkin finite-element technique. A Newton-Raphson algorithm is embedded in the Galerkin functional to formulate the problem in terms of the incremental changes in the dependent variables. Both triangular and quadrilateral finite elements are used to represent the continuum portions of the spatial domain. Line elements may be used to represent discrete conduits. 18 refs., 4 figs., 1 tab.
Zhang, Tong; Sentman, Charles L
2013-03-01
Tumor angiogenesis plays an important role in the development of solid tumors, and targeting the tumor vasculature has emerged as a strategy to prevent growth and progression of solid tumors. In this study, we show that murine tumor vasculature expresses Rae1, a ligand for a stimulatory NK receptor NKG2D. By genetic modification of T cells with an NKG2D-based chimeric Ag receptor, referred to as chNKG2D in which the NKG2D receptor is fused to the signaling domain of CD3ζ-chain, T cells were capable of targeting tumor vasculature leading to reduced tumor angiogenesis and tumor growth. This occurred even in tumors where the tumor cells themselves did not express NKG2D ligands. H5V, an endothelial cell line, expresses Rae1 and was lysed by chNKG2D-bearing T cells in a perforin-dependent manner. In vitro capillary tube formation was inhibited by chNKG2D T cells through IFN-γ and cell-cell contact mechanisms. The in vivo antiangiogenesis effects mediated by chNKG2D-bearing T cells at the tumor site were dependent on IFN-γ and perforin. These results provide a novel mechanism for NKG2D-based targeting of solid tumors.
NASA Astrophysics Data System (ADS)
Jaffe, Bruce E.; Goto, Kazuhisa; Sugawara, Daisuke; Richmond, Bruce M.; Fujino, Shige; Nishimura, Yuichi
2012-12-01
Tsunami deposits contain information about the flow that created them which can be interpreted to estimate tsunami magnitude. Sandy deposits near Sendai Airport are modeled using an inverse sediment transport model to explore the spatial and temporal variation of tsunami flow speed in the 11 March 2011 Tohoku-oki tsunami. The 2011 deposits contain grain-size signatures of both sediment transport convergences and sediment settling out of suspension. Sediment transport convergences form massive or inversely graded intervals. Sediment falling out of suspension forms a specific type of normal grading, termed suspension grading. The Jaffe and Gelfenbaum (2007) inverse sediment transport model, which relates the thickness and bulk grain size of suspension-graded intervals to tsunami flow speed, was applied to 24 suspension-graded intervals, ranging in thickness from 2 to 4 cm, at 7 trenches located from about 250 to 1350 m inland from the shoreline. Modeled tsunami flow speeds range from 2.2 to 9.0 m/s, and were strongly dependent on the choice of Manning's n roughness parameterization. Flow speeds were highest from about 75-300 m landward of the forested sand dunes where the tsunami encountered lower roughness in a low-lying area as it traveled downslope, and decreased by 16% as the tsunami moved inland over the subsequent 596 m. As many as 5 suspension-graded intervals, interpreted as forming during the onshore flow of up to 5 waves, were identified at each location, with a tendency for an inland decrease in the number of suspension-graded intervals suggesting fewer waves inland. Tsunami flows tended to be fastest in the lower two intervals (earlier waves) and slowest in the uppermost interval (last wave) of the deposits. Modeled reconstructions of the suspension-graded intervals at a vertical resolution of 1-cm reproduced observed upward fining of the distributions reasonably well, supporting the use of the inverse model. Estimates of the time required to form 99% of
NKG2D ligands mediate immunosurveillance of senescent cells.
Sagiv, Adi; Burton, Dominick G A; Moshayev, Zhana; Vadai, Ezra; Wensveen, Felix; Ben-Dor, Shifra; Golani, Ofra; Polic, Bojan; Krizhanovsky, Valery
2016-02-01
Cellular senescence is a stress response mechanism that limits tumorigenesis and tissue damage. Induction of cellular senescence commonly coincides with an immunogenic phenotype that promotes self-elimination by components of the immune system, thereby facilitating tumor suppression and limiting excess fibrosis during wound repair. The mechanisms by which senescent cells regulate their immune surveillance are not completely understood. Here we show that ligands of an activating Natural Killer (NK) cell receptor (NKG2D), MICA and ULBP2 are consistently up-regulated following induction of replicative senescence, oncogene-induced senescence and DNA damage - induced senescence. MICA and ULBP2 proteins are necessary for efficient NK-mediated cytotoxicity towards senescent fibroblasts. The mechanisms regulating the initial expression of NKG2D ligands in senescent cells are dependent on a DNA damage response, whilst continuous expression of these ligands is regulated by the ERK signaling pathway. In liver fibrosis, the accumulation of senescent activated stellate cells is increased in mice lacking NKG2D receptor leading to increased fibrosis. Overall, our results provide new insights into the mechanisms regulating the expression of immune ligands in senescent cells and reveal the importance of NKG2D receptor-ligand interaction in protecting against liver fibrosis. PMID:26878797
Rheological Properties of Quasi-2D Fluids in Microgravity
NASA Technical Reports Server (NTRS)
Stannarius, Ralf; Trittel, Torsten; Eremin, Alexey; Harth, Kirsten; Clark, Noel; Maclennan, Joseph; Glaser, Matthew; Park, Cheol; Hall, Nancy; Tin, Padetha
2015-01-01
In recent years, research on complex fluids and fluids in restricted geometries has attracted much attention in the scientific community. This can be attributed not only to the development of novel materials based on complex fluids but also to a variety of important physical phenomena which have barely been explored. One example is the behavior of membranes and thin fluid films, which can be described by two-dimensional (2D) rheology behavior that is quite different from 3D fluids. In this study, we have investigated the rheological properties of freely suspended films of a thermotropic liquid crystal in microgravity experiments. This model system mimics isotropic and anisotropic quasi 2D fluids [46]. We use inkjet printing technology to dispense small droplets (inclusions) onto the film surface. The motion of these inclusions provides information on the rheological properties of the films and allows the study of a variety of flow instabilities. Flat films have been investigated on a sub-orbital rocket flight and curved films (bubbles) have been studied in the ISS project OASIS. Microgravity is essential when the films are curved in order to avoid sedimentation. The experiments yield the mobility of the droplets in the films as well as the mutual mobility of pairs of particles. Experimental results will be presented for 2D-isotropic (smectic-A) and 2D-nematic (smectic-C) phases.
NASA Astrophysics Data System (ADS)
Montahaei, Mansoure; Oskooi, Behrooz
2014-02-01
An extension of an artificial neural network (ANN) approach to solve the magnetotelluric (MT) inverse problem for azimuthally anisotropic resistivities is presented and applied for a real dataset. Three different model classes, containing general 1-D and 2-D azimuthally anisotropic features, have been considered. For each model class, characteristics of three-layer feed forward ANNs trained through an error back propagation algorithm have been adjusted to approximate the inverse modeling function. It appears that, at least for synthetic models, reasonable results would be obtained by applying the amplitudes of the complex impedance tensor elements as inputs. Furthermore, the Levenberg-Marquart algorithm possesses optimal performance as a learning paradigm for this problem. The evaluation of applicability of the trained ANNs for unknown data sets excluded from the learning procedure reveals that the trained ANNs possess acceptable interpolation and extrapolation abilities to estimate model parameters accurately. This method was also successfully used for a field dataset wherein anisotropy had been previously recognized.
NASA Astrophysics Data System (ADS)
Nath, Saurabh; Mukherjee, Anish; Chatterjee, Souvick; Ganguly, Ranjan; Sen, Swarnendu; Mukhopadhyay, Achintya; Boreyko, Jonathan
2014-11-01
We have observed that capillarity forces may cause floatation in a few non-intuitive configurations. These may be divided into 2 categories: i) floatation of heavier liquid droplets on lighter immiscible ones and ii) fully submerged floatation of lighter liquid droplets in a heavier immiscible medium. We call these counter-intuitive because of the inverse floatation configuration. For case (i) we have identified and studied in detail the several factors affecting the shape and maximum volume of the floating drop. We used water and vegetable oil combinations as test fluids and established the relation between Bond Number and maximum volume contained in a floating drop (in the order of μL). For case (ii), we injected vegetable oil drop-wise into a pool of water. The fully submerged configuration of the drop is not stable and a slight perturbation to the system causes the droplet to burst and float in partially submerged condition. Temporal variation of a characteristic length of the droplet is analyzed using MATLAB image processing. The constraint of small Bond Number establishes the assumption of lubrication regime in the thin gap. A brief theoretical formulation also shows the temporal variation of the gap thickness. Jadavpur University, Jagadis Bose Centre of Excellence, Virginia Tech.
The NH2D hyperfine structure revealed by astrophysical observations
NASA Astrophysics Data System (ADS)
Daniel, F.; Coudert, L. H.; Punanova, A.; Harju, J.; Faure, A.; Roueff, E.; Sipilä, O.; Caselli, P.; Güsten, R.; Pon, A.; Pineda, J. E.
2016-02-01
Context. The 111-101 lines of ortho- and para-NH2D (o/p-NH2D) at 86 and 110 GHz, respectively, are commonly observed to provide constraints on the deuterium fractionation in the interstellar medium. In cold regions, the hyperfine structure that is due to the nitrogen (14N) nucleus is resolved. To date, this splitting is the only one that is taken into account in the NH2D column density estimates. Aims: We investigate how including the hyperfine splitting caused by the deuterium (D) nucleus affects the analysis of the rotational lines of NH2D. Methods: We present 30 m IRAM observations of the above mentioned lines and APEX o/p-NH2D observations of the 101-000 lines at 333 GHz. The hyperfine patterns of the observed lines were calculated taking into account the splitting induced by the D nucleus. The analysis then relies on line lists that either neglect or include the splitting induced by the D nucleus. Results: The hyperfine spectra are first analyzed with a line list that only includes the hyperfine splitting that is due to the 14N nucleus. We find inconsistencies between the line widths of the 101-000 and 111-101 lines, the latter being larger by a factor of ~1.6 ± 0.3. Such a large difference is unexpected because the two sets of lines probably originate from the same region. We next employed a newly computed line list for the o/p-NH2D transitions where the hyperfine structure induced by both nitrogen and deuterium nuclei was included. With this new line list, the analysis of the previous spectra leads to compatible line widths. Conclusions: Neglecting the hyperfine structure caused by D leads to overestimating the line widths of the o/p-NH2D lines at 3 mm. The error for a cold molecular core is about 50%. This error propagates directly to the column density estimate. We therefore recommend to take the hyperfine splittings caused by both the 14N and D nuclei into account in any analysis that relies on these lines. Based on observations carried out with the IRAM
Robust frequency-domain elastic Full Waveform Inversion: which norm?
NASA Astrophysics Data System (ADS)
Brossier, R.; Operto, S. O.; Virieux, J.
2009-12-01
Full waveform inversion (FWI) is becoming a powerful and efficient tool to derive high resolution models of subsurface visco-elastic parameters at different scales. In the frequency-domain (FD), 2D FWI is computationally affordable from both modeling and inversion viewpoints, because the inversion can be limited to few discrete frequencies when applied to wide-aperture acquisition geometries. However, FWI is an ill-posed data-fitting procedure that is sensitive to noise, inaccuracies of the starting model and definition of multi-parameter classes. The impact of the noise in FD FWI, when applied to decimated data sets, has been marginally illustrated in the past. We investigate here the sensitivities and performances of different minimization functionals, such as the least-square norm (L2), the least-absolute-values norm (L1), and some combinations of both (the Huber and the so-called Hybrid criteria), using realistic onshore and offshore synthetic case studies. The minimization functionals are implemented in a massively-parallel, 2D elastic FD FWI algorithm for imaging P- and S-wave velocities (VP and VS). Results show that the L1 norm provides the most reliable models, even when only few discrete frequencies are used in the inversion and when outliers pollute the data. The L2 norm can provide reliable results in the presence of uniform white noise if the data redundancy is increased by refining the frequency sampling interval in the inversion, at the expense of the computational efficiency. The Huber and the Hybrid criteria are shown to be sensitive to a threshold, which controls the transition between the L1 and L2 behaviors, and which requires tedious trial-and-error investigations for reliable estimation. The L1 norm provides a robust alternative to the L2 norm for the inversion of decimated data sets in the framework of efficient FD FWI. Synthetic onshore SEG/EAGE overthrust model experiment. Body and surface waves are jointly inverted. (a-b) true VP and VS
GBL-2D Version 1.0: a 2D geometry boolean library.
McBride, Cory L. (Elemental Technologies, American Fort, UT); Schmidt, Rodney Cannon; Yarberry, Victor R.; Meyers, Ray J.
2006-11-01
This report describes version 1.0 of GBL-2D, a geometric Boolean library for 2D objects. The library is written in C++ and consists of a set of classes and routines. The classes primarily represent geometric data and relationships. Classes are provided for 2D points, lines, arcs, edge uses, loops, surfaces and mask sets. The routines contain algorithms for geometric Boolean operations and utility functions. Routines are provided that incorporate the Boolean operations: Union(OR), XOR, Intersection and Difference. A variety of additional analytical geometry routines and routines for importing and exporting the data in various file formats are also provided. The GBL-2D library was originally developed as a geometric modeling engine for use with a separate software tool, called SummitView [1], that manipulates the 2D mask sets created by designers of Micro-Electro-Mechanical Systems (MEMS). However, many other practical applications for this type of software can be envisioned because the need to perform 2D Boolean operations can arise in many contexts.
A Parallel Processing Algorithm for Gravity Inversion
NASA Astrophysics Data System (ADS)
Frasheri, Neki; Bushati, Salvatore; Frasheri, Alfred
2013-04-01
The paper presents results of using MPI parallel processing for the 3D inversion of gravity anomalies. The work is done under the FP7 project HP-SEE (http://www.hp-see.eu/). The inversion of geophysical anomalies remains a challenge, and the use of parallel processing can be a tool to achieve better results, "compensating" the complexity of the ill-posed problem of inversion with the increase of volume of calculations. We considered the gravity as the simplest case of physical fields and experimented an algorithm based in the methodology known as CLEAN and developed by Högbom in 1974. The 3D geosection was discretized in finite cuboid elements and represented by a 3D array of nodes, while the ground surface where the anomaly is observed as a 2D array of points. Starting from a geosection with mass density zero in all nodes, iteratively the algorithm defines the 3D node that offers the best anomaly shape that approximates the observed anomaly minimizing the least squares error; the mass density in the best 3D node is modified with a prefixed density step and the related effect subtracted from the observed anomaly; the process continues until some criteria is fulfilled. Theoretical complexity of he algorithm was evaluated on the basis of iterations and run-time for a geosection discretized in different scales. We considered the average number N of nodes in one edge of the 3D array. The order of number of iterations was evaluated O(N^3); and the order of run-time was evaluated O(N^8). We used several different methods for the identification of the 3D node which effect offers the best least squares error in approximating the observed anomaly: unweighted least squares error for the whole 2D array of anomalous points; weighting least squares error by the inverted value of observed anomaly over each 3D node; and limiting the area of 2D anomalous points where least squares are calculated over shallow 3D nodes. By comparing results from the inversion of single body and two
Yamato, H.; Matsumoto, T.; Fukumoto, S.; Ikeda, K.; Ishizuka, S.; Ogata, E.
1989-01-01
Previous studies revealed that administration of 24,25-dihydroxyvitamin D3 (24,25-(OH)2D3) to calcium (Ca)-deficient rats causes a dose-dependent reduction in markedly elevated serum 1,25-(OH)2D3 level. Although the results suggested that the metabolism of 1,25-(OH)2D3 was accelerated by 24,25-(OH)2D3, those experiments could not define whether the enhanced metabolism of 1,25-(OH)2D3 played a role in the reduction in the serum 1,25-(OH)2D3 level. In the present study, in order to address this issue more specifically, serum 1,25-(OH)2D3 was maintained solely by exogenous administration through miniosmotic pumps of 1,25-(OH)2D3 into vitamin D-deficient rats. Thus, by measuring the serum 1,25-(OH)2D3 concentration, the effect of 24,25-(OH)2D3 on the MCR of 1,25-(OH)2D3 could be examined. Administration of 24,25-(OH)2D3 caused a dose-dependent enhancement in the MCR of 1,25-(OH)2D3, and 1 microgram/100 g rat.day 24,25-(OH)2D3, which elevated serum 24,25-(OH)2D3 to 8.6 +/- 1.3 ng/ml, significantly increased MCR and suppressed serum levels of 1,25-(OH)2D3. The effect of 24,25-(OH)2D3 on 1,25-(OH)2D3 metabolism developed with a rapid time course, and the recovery of iv injected (1 beta-3H)1,25-(OH)2D3 in blood was significantly reduced within 1 h. In addition, there was an increase in radioactivity in the water-soluble fraction of serum as well as in urine, suggesting that 1,25-(OH)2D3 is rapidly degraded to a water-soluble metabolite(s). Furthermore, the reduction in serum 1,25-(OH)2D3 was associated with a reduction in both serum and urinary Ca levels. Because the conversion of (3H)24,25-(OH)2D3 to (3H)1,24,25-(OH)2D3 or other metabolites was minimal in these rats, 24,25-(OH)2D3 appears to act without being converted into other metabolites. These results demonstrate that 24,25-(OH)2D3 rapidly stimulates the metabolism of 1,25-(OH)2D3 and reduces its serum level.
Periodically sheared 2D Yukawa systems
Kovács, Anikó Zsuzsa; Hartmann, Peter; Donkó, Zoltán
2015-10-15
We present non-equilibrium molecular dynamics simulation studies on the dynamic (complex) shear viscosity of a 2D Yukawa system. We have identified a non-monotonic frequency dependence of the viscosity at high frequencies and shear rates, an energy absorption maximum (local resonance) at the Einstein frequency of the system at medium shear rates, an enhanced collective wave activity, when the excitation is near the plateau frequency of the longitudinal wave dispersion, and the emergence of significant configurational anisotropy at small frequencies and high shear rates.
ENERGY LANDSCAPE OF 2D FLUID FORMS
Y. JIANG; ET AL
2000-04-01
The equilibrium states of 2D non-coarsening fluid foams, which consist of bubbles with fixed areas, correspond to local minima of the total perimeter. (1) The authors find an approximate value of the global minimum, and determine directly from an image how far a foam is from its ground state. (2) For (small) area disorder, small bubbles tend to sort inwards and large bubbles outwards. (3) Topological charges of the same sign repel while charges of opposite sign attract. (4) They discuss boundary conditions and the uniqueness of the pattern for fixed topology.
Lundqvist, E; Johansson, I; Ingelman-Sundberg, M
1999-01-21
The polymorphic CYP2D6 gene determines the rates at which several different classes of clinically important drugs are metabolized in vivo. A specific phenotype whereby a subject metabolizes drugs very rapidly (ultrarapid metabolizer, UM) has been shown to be caused by the presence of multiple active CYP2D6 genes on one allele. Hitherto, individuals with 1, 2, 3, 4, 5, or 13 CYP2D6 genes in tandem have been described for various ethnic groups. In the present investigation, we present results from restriction mapping of the CYP2D loci of individuals with two or more consecutive CYP2D6 genes, along with sequence analysis of this gene (CYP2D6*2). Our results indicate that alleles with duplicated or multiduplicated genes have occurred through unequal crossover at a specific breakpoint in the 3'-flanking region of the CYP2D6*2B allele with a specific repetitive sequence. In contrast, alleles with 13 copies of the gene are proposed to have been formed by unequal segregation and extrachromosomal replication of the acentric DNA. We present a rapid and efficient PCR-based allele-specific method for the detection of duplicated, multiduplicated, or amplified CYP2D6 genes.
On the edge of an inverse cascade.
Seshasayanan, Kannabiran; Benavides, Santiago Jose; Alexakis, Alexandros
2014-11-01
We demonstrate that systems with a parameter-controlled inverse cascade can exhibit critical behavior for which at the critical value of the control parameter the inverse cascade stops. In the vicinity of such a critical point, standard phenomenological estimates for the energy balance will fail since the energy flux towards large length scales becomes zero. We demonstrate this using the computationally tractable model of two-dimensional (2D) magnetohydrodynamics in a periodic box. In the absence of any external magnetic forcing, the system reduces to hydrodynamic fluid turbulence with an inverse energy cascade. In the presence of strong magnetic forcing, the system behaves as 2D magnetohydrodynamic turbulence with forward energy cascade. As the amplitude of the magnetic forcing is varied, a critical value is met for which the energy flux towards the large scales becomes zero. Close to this point, the energy flux scales as a power law with the departure from the critical point and the normalized amplitude of the fluctuations diverges. Similar behavior is observed for the flux of the square vector potential for which no inverse flux is observed for weak magnetic forcing, while a finite inverse flux is observed for magnetic forcing above the critical point. We conjecture that this behavior is generic for systems of variable inverse cascade. PMID:25493730
A hierarchically porous anatase TiO2 coated-WO3 2D IO bilayer film and its photochromic properties.
Li, Hua; Wu, Huazhong; Xiao, Jiajia; Su, Yanli; Robichaud, Jacques; Brüning, Ralf; Djaoued, Yahia
2016-01-18
A hierarchically porous anatase TiO2 coated-WO3 2D inverse opal (IO) bilayer film was fabricated on ITO glass using a layer by layer route with a hierarchically porous TiO2 top layer and an ordered super-macroporous WO3 2D IO bottom layer. This novel TiO2 coated-WO3 2D IO bilayer film was evaluated for photochromic applications. PMID:26576930
A hierarchically porous anatase TiO2 coated-WO3 2D IO bilayer film and its photochromic properties.
Li, Hua; Wu, Huazhong; Xiao, Jiajia; Su, Yanli; Robichaud, Jacques; Brüning, Ralf; Djaoued, Yahia
2016-01-18
A hierarchically porous anatase TiO2 coated-WO3 2D inverse opal (IO) bilayer film was fabricated on ITO glass using a layer by layer route with a hierarchically porous TiO2 top layer and an ordered super-macroporous WO3 2D IO bottom layer. This novel TiO2 coated-WO3 2D IO bilayer film was evaluated for photochromic applications.
Microwave Assisted 2D Materials Exfoliation
NASA Astrophysics Data System (ADS)
Wang, Yanbin
Two-dimensional materials have emerged as extremely important materials with applications ranging from energy and environmental science to electronics and biology. Here we report our discovery of a universal, ultrafast, green, solvo-thermal technology for producing excellent-quality, few-layered nanosheets in liquid phase from well-known 2D materials such as such hexagonal boron nitride (h-BN), graphite, and MoS2. We start by mixing the uniform bulk-layered material with a common organic solvent that matches its surface energy to reduce the van der Waals attractive interactions between the layers; next, the solutions are heated in a commercial microwave oven to overcome the energy barrier between bulk and few-layers states. We discovered the minutes-long rapid exfoliation process is highly temperature dependent, which requires precise thermal management to obtain high-quality inks. We hypothesize a possible mechanism of this proposed solvo-thermal process; our theory confirms the basis of this novel technique for exfoliation of high-quality, layered 2D materials by using an as yet unknown role of the solvent.
Multienzyme Inkjet Printed 2D Arrays.
Gdor, Efrat; Shemesh, Shay; Magdassi, Shlomo; Mandler, Daniel
2015-08-19
The use of printing to produce 2D arrays is well established, and should be relatively facile to adapt for the purpose of printing biomaterials; however, very few studies have been published using enzyme solutions as inks. Among the printing technologies, inkjet printing is highly suitable for printing biomaterials and specifically enzymes, as it offers many advantages. Formulation of the inkjet inks is relatively simple and can be adjusted to a variety of biomaterials, while providing nonharmful environment to the enzymes. Here we demonstrate the applicability of inkjet printing for patterning multiple enzymes in a predefined array in a very straightforward, noncontact method. Specifically, various arrays of the enzymes glucose oxidase (GOx), invertase (INV) and horseradish peroxidase (HP) were printed on aminated glass surfaces, followed by immobilization using glutardialdehyde after printing. Scanning electrochemical microscopy (SECM) was used for imaging the printed patterns and to ascertain the enzyme activity. The successful formation of 2D arrays consisting of enzymes was explored as a means of developing the first surface confined enzyme based logic gates. Principally, XOR and AND gates, each consisting of two enzymes as the Boolean operators, were assembled, and their operation was studied by SECM. PMID:26214072
MT2DInvMatlab—A program in MATLAB and FORTRAN for two-dimensional magnetotelluric inversion
NASA Astrophysics Data System (ADS)
Lee, Seong Kon; Kim, Hee Joon; Song, Yoonho; Lee, Choon-Ki
2009-08-01
MT2DInvMatlab is an open-source MATLAB® software package for two-dimensional (2D) inversion of magnetotelluric (MT) data; it is written in mixed languages of MATLAB and FORTRAN. MT2DInvMatlab uses the finite element method (FEM) to compute 2D MT model responses, and smoothness-constrained least-squares inversion with a spatially variable regularization parameter algorithm to stabilize the inversion process and provide a high-resolution optimal earth model. It is also able to include terrain effects in inversion by incorporating topography into a forward model. This program runs under the MATLAB environment so that users can utilize the existing general interface of MATLAB, while some specific functions are written in FORTRAN 90 to speed up computation and reuse pre-existing FORTRAN code in the MATLAB environment with minimal modification. This program has been tested using synthetic models, including one with variable topography, and on field data. The results were assessed by comparing inverse models obtained with MT2DInvMatlab and with a non-linear conjugate gradient (NLCG) algorithm. In both tests the new inversion software reconstructs the subsurface resistivity structure very closely and provides an improvement in both resolution and stability.
A new stationary gridline artifact suppression method based on the 2D discrete wavelet transform
Tang, Hui; Tong, Dan; Dong Bao, Xu; Dillenseger, Jean-Louis
2015-04-15
Purpose: In digital x-ray radiography, an antiscatter grid is inserted between the patient and the image receptor to reduce scattered radiation. If the antiscatter grid is used in a stationary way, gridline artifacts will appear in the final image. In most of the gridline removal image processing methods, the useful information with spatial frequencies close to that of the gridline is usually lost or degraded. In this study, a new stationary gridline suppression method is designed to preserve more of the useful information. Methods: The method is as follows. The input image is first recursively decomposed into several smaller subimages using a multiscale 2D discrete wavelet transform. The decomposition process stops when the gridline signal is found to be greater than a threshold in one or several of these subimages using a gridline detection module. An automatic Gaussian band-stop filter is then applied to the detected subimages to remove the gridline signal. Finally, the restored image is achieved using the corresponding 2D inverse discrete wavelet transform. Results: The processed images show that the proposed method can remove the gridline signal efficiently while maintaining the image details. The spectra of a 1D Fourier transform of the processed images demonstrate that, compared with some existing gridline removal methods, the proposed method has better information preservation after the removal of the gridline artifacts. Additionally, the performance speed is relatively high. Conclusions: The experimental results demonstrate the efficiency of the proposed method. Compared with some existing gridline removal methods, the proposed method can preserve more information within an acceptable execution time.
1,25(OH)2D3 increases membrane associated protein kinase C in MDBK cells.
Simboli-Campbell, M; Franks, D J; Welsh, J
1992-01-01
To determine whether 1,25-dihydroxycholecalciferol [1,25(OH)2D3] affects protein kinase C (PKC) activity in kidney, as has been demonstrated in HL-60 cells we measured 1,25(OH)2D3 binding, PKC activity and PKC immunoreactivity in Madin Darby bovine kidney (MDBK) cells, a normal renal epithelial cell line derived from bovine kidney. Our data demonstrate that MDBK cells exhibit specific high affinity binding for 1,25(OH)2D3, indicating the presence of the vitamin D receptor (VDR). Treatment of MDBK cells with 1,25(OH)2D3 for 24 h increased membrane PKC activity and immunoreactivity. The effect of 1,25(OH)2D3 was dose-dependent, with a peak effect observed at 10(-7)M 1,25(OH)2D3. The 1,25(OH)2D3 induced increase in membrane PKC was paralleled by a comparable decrease in cytosolic PKC activity and amount. Although time course studies were consistent with a VDR mediated effect of 1,25(OH)2D3 on PKC protein synthesis, total PKC activity was not increased by 1,25(OH)2D3, suggesting an effect on PKC translocation or localization. These results suggest that 1,25(OH)2D3 modulates PKC mediated events in kidney, a classic target for this steroid hormone.
Flow transitions in a 2D directional solidification model
NASA Technical Reports Server (NTRS)
Larroude, Philippe; Ouazzani, Jalil; Alexander, J. Iwan D.
1992-01-01
Flow transitions in a Two Dimensional (2D) model of crystal growth were examined using the Bridgman-Stockbarger me thod. Using a pseudo-spectral Chebyshev collocation method, the governing equations yield solutions which exhibit a symmetry breaking flow tansition and oscillatory behavior indicative of a Hopf bifurcation at higher values of Ra. The results are discussed from fluid dynamic viewpoint, and broader implications for process models are also addressed.
Energy level transitions of gas in a 2D nanopore
Grinyaev, Yurii V.; Chertova, Nadezhda V.; Psakhie, Sergei G.
2015-10-27
An analytical study of gas behavior in a 2D nanopore was performed. It is shown that the temperature dependence of gas energy can be stepwise due to transitions from one size-quantized subband to another. Taking into account quantum size effects results in energy level transitions governed by the nanopore size, temperature and gas density. This effect leads to an abrupt change of gas heat capacity in the nanopore at the above varying system parameters.
The Kubo-Greenwood expression and 2d MIT transport
NASA Astrophysics Data System (ADS)
Castner, Theodore
2010-03-01
The 2d MIT in GaAs heterostructures (p- and n-type)features a mobility that drops continuously as the reduced density x= n/nc-1 is decreased. The Kubo-Greenwood result [1] predicts μ = (eɛh/hnc)α^2(x) where α is a normalized DOS. α(x)is obtained from the data [p-type, Gao et al. [2]; n-type Lilly et al. [3
NASA Astrophysics Data System (ADS)
Benjamini, Dan; Basser, Peter J.
2016-10-01
Measuring multidimensional (e.g., 2D) relaxation spectra in NMR and MRI clinical applications is a holy grail of the porous media and biomedical MR communities. The main bottleneck is the inversion of Fredholm integrals of the first kind, an ill-conditioned problem requiring large amounts of data to stabilize a solution. We suggest a novel experimental design and processing framework to accelerate and improve the reconstruction of such 2D spectra that uses a priori information from the 1D projections of spectra, or marginal distributions. These 1D marginal distributions provide powerful constraints when 2D spectra are reconstructed, and their estimation requires an order of magnitude less data than a conventional 2D approach. This marginal distributions constrained optimization (MADCO) methodology is demonstrated here with a polyvinylpyrrolidone-water phantom that has 3 distinct peaks in the 2D D-T1 space. The stability, sensitivity to experimental parameters, and accuracy of this new approach are compared with conventional methods by serially subsampling the full data set. While the conventional, unconstrained approach performed poorly, the new method had proven to be highly accurate and robust, only requiring a fraction of the data. Additionally, synthetic T1 -T2 data are presented to explore the effects of noise on the estimations, and the performance of the proposed method with a smooth and realistic 2D spectrum. The proposed framework is quite general and can also be used with a variety of 2D MRI experiments (D-T2,T1 -T2, D -D, etc.), making these potentially feasible for preclinical and even clinical applications for the first time.
Benjamini, Dan; Basser, Peter J
2016-10-01
Measuring multidimensional (e.g., 2D) relaxation spectra in NMR and MRI clinical applications is a holy grail of the porous media and biomedical MR communities. The main bottleneck is the inversion of Fredholm integrals of the first kind, an ill-conditioned problem requiring large amounts of data to stabilize a solution. We suggest a novel experimental design and processing framework to accelerate and improve the reconstruction of such 2D spectra that uses a priori information from the 1D projections of spectra, or marginal distributions. These 1D marginal distributions provide powerful constraints when 2D spectra are reconstructed, and their estimation requires an order of magnitude less data than a conventional 2D approach. This marginal distributions constrained optimization (MADCO) methodology is demonstrated here with a polyvinylpyrrolidone-water phantom that has 3 distinct peaks in the 2D D-T1 space. The stability, sensitivity to experimental parameters, and accuracy of this new approach are compared with conventional methods by serially subsampling the full data set. While the conventional, unconstrained approach performed poorly, the new method had proven to be highly accurate and robust, only requiring a fraction of the data. Additionally, synthetic T1-T2 data are presented to explore the effects of noise on the estimations, and the performance of the proposed method with a smooth and realistic 2D spectrum. The proposed framework is quite general and can also be used with a variety of 2D MRI experiments (D-T2,T1-T2,D-D, etc.), making these potentially feasible for preclinical and even clinical applications for the first time. PMID:27543810
Coordinate transformation method for the solution of inverse problem in 2D and 3D scatterometry
NASA Astrophysics Data System (ADS)
Ponnusamy, Sekar
2005-05-01
For scatterometry applications, diffraction analysis of gratings is carried out by using Rigorous Coupled Wave Analysis (RCWA). Though RCWA method is originally developed for lamellar gratings, arbitrary profiles can be analyzed using staircase approximation with S-Matrix propagation of field components. For improved accuracy, more number of Fourier waves need to be included in Floquet-Bloch expansion of the field components and also more number of slices are to be made in staircase approximation. These requirements increase the time required for the analysis. A coordinate transformation method (CTM) developed by Chandezon et. al renders the arbitrary grating profile into a plane surface in the new coordinate system and hence it does not require slicing. This method is extended to 3D structures by several authors notably, by Harris et al for non-orthogonal unit cells and by Granet for correct Fourier expansion. Also extended is to handle sharp-edged gratings through adaptive spatial resolution. In this paper, an attempt is made to employ CTM with correct Fourier expansion in conjunction with adaptive spatial resolution, for scatterometry applications. A MATLAB program is developed, and thereby, demonstrated that CTM can be used for diffraction analysis of trapezoidal profiles that are typically encountered in scatterometry applications.
NASA Astrophysics Data System (ADS)
Williamson, Nathan H.; Röding, Magnus; Galvosas, Petrik; Miklavcic, Stanley J.; Nydén, Magnus
2016-08-01
We present the pseudo 2-D relaxation model (P2DRM), a method to estimate multidimensional probability distributions of material parameters from independent 1-D measurements. We illustrate its use on 1-D T1 and T2 relaxation measurements of saturated rock and evaluate it on both simulated and experimental T1-T2 correlation measurement data sets. Results were in excellent agreement with the actual, known 2-D distribution in the case of the simulated data set. In both the simulated and experimental case, the functional relationships between T1 and T2 were in good agreement with the T1-T2 correlation maps from the 2-D inverse Laplace transform of the full 2-D data sets. When a 1-D CPMG experiment is combined with a rapid T1 measurement, the P2DRM provides a double-shot method for obtaining a T1-T2 relationship, with significantly decreased experimental time in comparison to the full T1-T2 correlation measurement.
Continuum Nonsimple Loops and 2D Critical Percolation
NASA Astrophysics Data System (ADS)
Camia, Federico; Newman, Charles M.
2004-08-01
Substantial progress has been made in recent years on the 2D critical percolation scaling limit and its conformal invariance properties. In particular, chordal SLE 6(the Stochastic Loewner Evolution with parameter κ=6) was, in the work of Schramm and of Smirnov, identified as the scaling limit of the critical percolation "exploration process." In this paper we use that and other results to construct what we argue is the fullscaling limit of the collection of allclosed contours surrounding the critical percolation clusters on the 2D triangular lattice. This random process or gas of continuum nonsimple loops in Bbb R2is constructed inductively by repeated use of chordal SLE 6. These loops do not cross but do touch each other—indeed, any two loops are connected by a finite "path" of touching loops.
Shilling, Richard Z; Robbie, Trevor Q; Bailloeul, Timothée; Mewes, Klaus; Mersereau, Russell M; Brummer, Marijn E
2009-05-01
A novel super-resolution reconstruction (SRR) framework in magnetic resonance imaging (MRI) is proposed. Its purpose is to produce images of both high resolution and high contrast desirable for image-guided minimally invasive brain surgery. The input data are multiple 2-D multislice inversion recovery MRI scans acquired at orientations with regular angular spacing rotated around a common frequency encoding axis. The output is a 3-D volume of isotropic high resolution. The inversion process resembles a localized projection reconstruction problem. Iterative algorithms for reconstruction are based on the projection onto convex sets (POCS) formalism. Results demonstrate resolution enhancement in simulated phantom studies, and ex vivo and in vivo human brain scans, carried out on clinical scanners. A comparison with previously published SRR methods shows favorable characteristics in the proposed approach.
Grid Cell Responses in 1D Environments Assessed as Slices through a 2D Lattice.
Yoon, KiJung; Lewallen, Sam; Kinkhabwala, Amina A; Tank, David W; Fiete, Ila R
2016-03-01
Grid cells, defined by their striking periodic spatial responses in open 2D arenas, appear to respond differently on 1D tracks: the multiple response fields are not periodically arranged, peak amplitudes vary across fields, and the mean spacing between fields is larger than in 2D environments. We ask whether such 1D responses are consistent with the system's 2D dynamics. Combining analytical and numerical methods, we show that the 1D responses of grid cells with stable 1D fields are consistent with a linear slice through a 2D triangular lattice. Further, the 1D responses of comodular cells are well described by parallel slices, and the offsets in the starting points of the 1D slices can predict the measured 2D relative spatial phase between the cells. From these results, we conclude that the 2D dynamics of these cells is preserved in 1D, suggesting a common computation during both types of navigation behavior. PMID:26898777
2D Electrostatic Actuation of Microshutter Arrays
NASA Technical Reports Server (NTRS)
Burns, Devin E.; Oh, Lance H.; Li, Mary J.; Kelly, Daniel P.; Kutyrev, Alexander S.; Moseley, Samuel H.
2015-01-01
Electrostatically actuated microshutter arrays consisting of rotational microshutters (shutters that rotate about a torsion bar) were designed and fabricated through the use of models and experiments. Design iterations focused on minimizing the torsional stiffness of the microshutters, while maintaining their structural integrity. Mechanical and electromechanical test systems were constructed to measure the static and dynamic behavior of the microshutters. The torsional stiffness was reduced by a factor of four over initial designs without sacrificing durability. Analysis of the resonant behavior of the microshutters demonstrates that the first resonant mode is a torsional mode occurring around 3000 Hz. At low vacuum pressures, this resonant mode can be used to significantly reduce the drive voltage necessary for actuation requiring as little as 25V. 2D electrostatic latching and addressing was demonstrated using both a resonant and pulsed addressing scheme.
2D Electrostatic Actuation of Microshutter Arrays
NASA Technical Reports Server (NTRS)
Burns, Devin E.; Oh, Lance H.; Li, Mary J.; Jones, Justin S.; Kelly, Daniel P.; Zheng, Yun; Kutyrev, Alexander S.; Moseley, Samuel H.
2015-01-01
An electrostatically actuated microshutter array consisting of rotational microshutters (shutters that rotate about a torsion bar) were designed and fabricated through the use of models and experiments. Design iterations focused on minimizing the torsional stiffness of the microshutters, while maintaining their structural integrity. Mechanical and electromechanical test systems were constructed to measure the static and dynamic behavior of the microshutters. The torsional stiffness was reduced by a factor of four over initial designs without sacrificing durability. Analysis of the resonant behavior of the microshutter arrays demonstrates that the first resonant mode is a torsional mode occurring around 3000 Hz. At low vacuum pressures, this resonant mode can be used to significantly reduce the drive voltage necessary for actuation requiring as little as 25V. 2D electrostatic latching and addressing was demonstrated using both a resonant and pulsed addressing scheme.
2D quantum gravity from quantum entanglement.
Gliozzi, F
2011-01-21
In quantum systems with many degrees of freedom the replica method is a useful tool to study the entanglement of arbitrary spatial regions. We apply it in a way that allows them to backreact. As a consequence, they become dynamical subsystems whose position, form, and extension are determined by their interaction with the whole system. We analyze, in particular, quantum spin chains described at criticality by a conformal field theory. Its coupling to the Gibbs' ensemble of all possible subsystems is relevant and drives the system into a new fixed point which is argued to be that of the 2D quantum gravity coupled to this system. Numerical experiments on the critical Ising model show that the new critical exponents agree with those predicted by the formula of Knizhnik, Polyakov, and Zamolodchikov.
Graphene suspensions for 2D printing
NASA Astrophysics Data System (ADS)
Soots, R. A.; Yakimchuk, E. A.; Nebogatikova, N. A.; Kotin, I. A.; Antonova, I. V.
2016-04-01
It is shown that, by processing a graphite suspension in ethanol or water by ultrasound and centrifuging, it is possible to obtain particles with thicknesses within 1-6 nm and, in the most interesting cases, 1-1.5 nm. Analogous treatment of a graphite suspension in organic solvent yields eventually thicker particles (up to 6-10 nm thick) even upon long-term treatment. Using the proposed ink based on graphene and aqueous ethanol with ethylcellulose and terpineol additives for 2D printing, thin (~5 nm thick) films with sheet resistance upon annealing ~30 MΩ/□ were obtained. With the ink based on aqueous graphene suspension, the sheet resistance was ~5-12 kΩ/□ for 6- to 15-nm-thick layers with a carrier mobility of ~30-50 cm2/(V s).
Duality Between Spin Networks and the 2D Ising Model
NASA Astrophysics Data System (ADS)
Bonzom, Valentin; Costantino, Francesco; Livine, Etera R.
2016-06-01
The goal of this paper is to exhibit a deep relation between the partition function of the Ising model on a planar trivalent graph and the generating series of the spin network evaluations on the same graph. We provide respectively a fermionic and a bosonic Gaussian integral formulation for each of these functions and we show that they are the inverse of each other (up to some explicit constants) by exhibiting a supersymmetry relating the two formulations. We investigate three aspects and applications of this duality. First, we propose higher order supersymmetric theories that couple the geometry of the spin networks to the Ising model and for which supersymmetric localization still holds. Secondly, after interpreting the generating function of spin network evaluations as the projection of a coherent state of loop quantum gravity onto the flat connection state, we find the probability distribution induced by that coherent state on the edge spins and study its stationary phase approximation. It is found that the stationary points correspond to the critical values of the couplings of the 2D Ising model, at least for isoradial graphs. Third, we analyze the mapping of the correlations of the Ising model to spin network observables, and describe the phase transition on those observables on the hexagonal lattice. This opens the door to many new possibilities, especially for the study of the coarse-graining and continuum limit of spin networks in the context of quantum gravity.
Dephosphorylation of MAP2D enhances its binding to vimentin in preovulatory ovarian granulosa cells.
Flynn, Maxfield P; Fiedler, Sarah E; Karlsson, Amelia B; Carr, Daniel W; Maizels, Evelyn T; Hunzicker-Dunn, Mary
2016-08-01
Preovulatory granulosa cells express the low-molecular-mass MAP2D variant of microtubule-associated protein 2 (MAP2). Activation of the luteinizing hormone choriogonadotropin receptor by human choriogonadotropin (hCG) promotes dephosphorylation of MAP2D on Thr256 and Thr259. We sought to evaluate the association of MAP2D with the cytoskeleton, and the effect of hCG on this association. MAP2D partially colocalized, as assessed by confocal immunofluorescence microscopy, with the vimentin intermediate filament and microtubule cytoskeletons in naive cells. In vitro binding studies showed that MAP2D bound directly to vimentin and β-tubulin. Phosphorylation of recombinant MAP2D on Thr256 and Thr259, which mimics the phosphorylation status of MAP2D in naive cells, reduces binding of MAP2D to vimentin and tubulin by two- and three-fold, respectively. PKA-dependent phosphorylation of vimentin (Ser32 and Ser38) promoted binding of vimentin to MAP2D and increased contraction of granulosa cells with reorganization of vimentin filaments and MAP2D from the periphery into a thickened layer surrounding the nucleus and into prominent cellular extensions. Chemical disruption of vimentin filament organization increased progesterone production. Taken together, these results suggest that hCG-stimulated dephosphorylation of MAP2D at Thr256 and Thr259, phosphorylation of vimentin at Ser38 and Ser72, and the resulting enhanced binding of MAP2D to vimentin might contribute to the progesterone synthetic response required for ovulation.
On parameterization of the inverse problem for estimating aquifer properties using tracer data
Kowalsky, M. B.; Finsterle, Stefan A.; Williams, Kenneth H.; Murray, Christopher J.; Commer, Michael; Newcomer, Darrell R.; Englert, Andreas L.; Steefel, Carl I.; Hubbard, Susan
2012-06-11
We consider a field-scale tracer experiment conducted in 2007 in a shallow uranium-contaminated aquifer at Rifle, Colorado. In developing a reliable approach for inferring hydrological properties at the site through inverse modeling of the tracer data, decisions made on how to parameterize heterogeneity (i.e., how to represent a heterogeneous distribution using a limited number of parameters that are amenable to estimation) are of paramount importance. We present an approach for hydrological inversion of the tracer data and explore, using a 2D synthetic example at first, how parameterization affects the solution, and how additional characterization data could be incorporated to reduce uncertainty. Specifically, we examine sensitivity of the results to the configuration of pilot points used in a geostatistical parameterization, and to the sampling frequency and measurement error of the concentration data. A reliable solution of the inverse problem is found when the pilot point configuration is carefully implemented. In addition, we examine the use of a zonation parameterization, in which the geometry of the geological facies is known (e.g., from geophysical data or core data), to reduce the non-uniqueness of the solution and the number of unknown parameters to be estimated. When zonation information is only available for a limited region, special treatment in the remainder of the model is necessary, such as using a geostatistical parameterization. Finally, inversion of the actual field data is performed using 2D and 3D models, and results are compared with slug test data.
Gaedigk, Andrea; Bradford, L Dianne; Alander, Sarah W; Leeder, J Steven
2006-04-01
Unexplained cases of CYP2D6 genotype/phenotype discordance continue to be discovered. In previous studies, several African Americans with a poor metabolizer phenotype carried the reduced function CYP2D6*10 allele in combination with a nonfunctional allele. We pursued the possibility that these alleles harbor either a known sequence variation (i.e., CYP2D6*36 carrying a gene conversion in exon 9 along the CYP2D6*10-defining 100C>T single-nucleotide polymorphism) or novel sequences variation(s). Discordant cases were evaluated by long-range polymerase chain reaction (PCR) to test for gene rearrangement events, and a 6.6-kilobase pair PCR product encompassing the CYP2D6 gene was cloned and entirely sequenced. Thereafter, allele frequencies were determined in different study populations comprising whites, African Americans, and Asians. Analyses covering the CYP2D7 to 2D6 gene region established that CYP2D6*36 did not only exist as a gene duplication (CYP2D6*36x2) or in tandem with *10 (CYP2D6*36+*10), as previously reported, but also by itself. This "single" CYP2D6*36 allele was found in nine African Americans and one Asian, but was absent in the whites tested. Ultimately, the presence of CYP2D6*36 resolved genotype/phenotype discordance in three cases. We also discovered an exon 9 conversion-positive CYP2D6*4 gene in a duplication arrangement (CYP2D6*4Nx2) and a CYP2D6*4 allele lacking 100C>T (CYP2D6*4M) in two white subjects. The discovery of an allele that carries only one CYP2D6*36 gene copy provides unequivocal evidence that both CYP2D6*36 and *36x2 are associated with a poor metabolizer phenotype. Given a combined frequency of between 0.5 and 3% in African Americans and Asians, genotyping for CYP2D6*36 should improve the accuracy of genotype-based phenotype prediction in these populations.
F-theory and 2d (0, 2) theories
NASA Astrophysics Data System (ADS)
Schäfer-Nameki, Sakura; Weigand, Timo
2016-05-01
F-theory compactified on singular, elliptically fibered Calabi-Yau five-folds gives rise to two-dimensional gauge theories preserving N = (0 , 2) supersymmetry. In this paper we initiate the study of such compactifications and determine the dictionary between the geometric data of the elliptic fibration and the 2d gauge theory such as the matter content in terms of (0 , 2) superfields and their supersymmetric couplings. We study this setup both from a gauge-theoretic point of view, in terms of the partially twisted 7-brane theory, and provide a global geometric description based on the structure of the elliptic fibration and its singularities. Global consistency conditions are determined and checked against the dual M-theory compactification to one dimension. This includes a discussion of gauge anomalies, the structure of the Green-Schwarz terms and the Chern-Simons couplings in the dual M-theory supersymmetric quantum mechanics. Furthermore, by interpreting the resulting 2d (0 , 2) theories as heterotic worldsheet theories, we propose a correspondence between the geometric data of elliptically fibered Calabi-Yau five-folds and the target space of a heterotic gauged linear sigma-model (GLSM). In particular the correspondence between the Landau-Ginsburg and sigma-model phase of a 2d (0 , 2) GLSM is realized via different T-branes or gluing data in F-theory.
Dopamine D2/D3 receptor availability and venturesomeness.
Bernow, Nina; Yakushev, Igor; Landvogt, Christian; Buchholz, Hans-Georg; Smolka, Michael N; Bartenstein, Peter; Lieb, Klaus; Gründer, Gerhard; Vernaleken, Ingo; Schreckenberger, Mathias; Fehr, Christoph
2011-08-30
The construct of impulsivity is considered as a major trait of personality. There is growing evidence that the mesolimbic dopamine system plays an important role in the modulation of impulsivity and venturesomeness, the two key components within the impulsivity-construct. The aim of the present study was to explore an association between trait impulsivity measured with self-assessment and the dopaminergic neurotransmission as measured by positron emission tomography (PET) in a cohort of healthy male subjects. In vivo D2/D3 receptor availability was determined with [(18)F]fallypride PET in 18 non-smoking healthy subjects. The character trait impulsivity was measured using the Impulsiveness-Venturesomeness-Empathy questionnaire (I7). Image processing and statistical analysis was performed on a voxel-by-voxel basis using statistical parametric mapping (SPM) software. The I7 subscale venturesomeness correlated positively with the D2/D3 receptor availability within the left temporal cortex and the thalamus. Measures on the I7 subscale impulsiveness and empathy did not correlate with the D2/D3 receptor availability in any brain region investigated. Our results suggest the involvement of extrastriatal dopaminergic neurotransmission in venturesomeness, a component of impulsivity. PMID:21689908
An Intercomparison of 2-D Models Within a Common Framework
NASA Technical Reports Server (NTRS)
Weisenstein, Debra K.; Ko, Malcolm K. W.; Scott, Courtney J.; Jackman, Charles H.; Fleming, Eric L.; Considine, David B.; Kinnison, Douglas E.; Connell, Peter S.; Rotman, Douglas A.; Bhartia, P. K. (Technical Monitor)
2002-01-01
A model intercomparison among the Atmospheric and Environmental Research (AER) 2-D model, the Goddard Space Flight Center (GSFC) 2-D model, and the Lawrence Livermore National Laboratory 2-D model allows us to separate differences due to model transport from those due to the model's chemical formulation. This is accomplished by constructing two hybrid models incorporating the transport parameters of the GSFC and LLNL models within the AER model framework. By comparing the results from the native models (AER and e.g. GSFC) with those from the hybrid model (e.g. AER chemistry with GSFC transport), differences due to chemistry and transport can be identified. For the analysis, we examined an inert tracer whose emission pattern is based on emission from a High Speed Civil Transport (HSCT) fleet; distributions of trace species in the 2015 atmosphere; and the response of stratospheric ozone to an HSCT fleet. Differences in NO(y) in the upper stratosphere are found between models with identical transport, implying different model representations of atmospheric chemical processes. The response of O3 concentration to HSCT aircraft emissions differs in the models from both transport-dominated differences in the HSCT-induced perturbations of H2O and NO(y) as well as from differences in the model represent at ions of O3 chemical processes. The model formulations of cold polar processes are found to be the most significant factor in creating large differences in the calculated ozone perturbations
Bonaccio, Marialaura; Di Castelnuovo, Augusto; De Curtis, Amalia; Costanzo, Simona; Bracone, Francesca; Persichillo, Mariarosaria; Donati, Maria Benedetta; de Gaetano, Giovanni; Iacoviello, Licia
2015-09-14
Nut intake has been associated with reduced inflammatory status and lower risk of CVD and mortality. The aim of this study was to examine the relationship between nut consumption and mortality and the role of inflammation. We conducted a population-based prospective investigation on 19 386 subjects enrolled in the Moli-sani study. Food intake was recorded by the Italian version of the European Project Investigation into Cancer and Nutrition FFQ. C-reactive protein, leucocyte and platelet counts and the neutrophil:lymphocyte ratio were used as biomarkers of low-grade inflammation. Hazard ratios (HR) were calculated using multivariable Cox proportional hazard models. During a median follow-up of 4·3 years, 334 all-cause deaths occurred. As compared with subjects who never ate nuts, rare intake (≤2 times/month) was inversely associated with mortality (multivariable HR=0·68; 95 % CI 0·54, 0·87). At intake ≥8 times/month, a greater protection was observed (HR=0·53; 0·32, 0·90). Nut intake (v. no intake) conveyed a higher protection to individuals poorly adhering to the Mediterranean diet (MD). A significant reduction in cancer deaths (HR=0·64; 95 % CI 0·44, 0·94) was also observed, whereas the impact on CVD deaths was limited to an inverse, but not significant, trend. Biomarkers of low-grade inflammation were reduced in nut consumers but did not account for the association with mortality. In conclusion, nut intake was associated with reduced cancer and total mortality. The protection was stronger in individuals with lower adherence to MD, whereas it was similar in high-risk groups (diabetics, obese, smokers or those with the metabolic syndrome), as compared with low-risk subjects. Inflammation did not explain the observed relationship.
Does gravity help to improve seismic inversion for density?
NASA Astrophysics Data System (ADS)
Blom, Nienke; Böhm, Christian; Fichtner, Andreas
2016-04-01
Density is one of the most important material properties that influence the dynamics of our planet's interior, and knowledge of it alongside with knowledge of seismic velocities will help constrain composition more directly. However, the variation of density inside the Earth is poorly known. The travel times of seismic waves, the classical tool to probe the Earth's interior, are barely sensitive to density (with large tradeoffs) and gravity is so extremely non-unique that very little information can be extracted from it without placing very strong prior constraints. As a result, density has, up until now, usually only been regarded as a derived quantity, which may lead to erroneous interpretations. Here, we aim to determine to what extent it is possible to image density as an independent parameter using modern geophysical techniques. The main technique is seismic (full) waveform inversion, which is more sensitive to density than travel-times alone, for the simple reason that more information of the seismogram is being used: basically the amplitude and phase of every wiggle. We construct synthetic tests in 2-D where density is a completely independent parameter from S-wave velocity and P-wave velocity - this setup (albeit physically unrealistic) has the advantage that our ability to image density independently is assessed in an unbiased way. We find that it is indeed possible to image density using waveform inversion. If prior information, such as constraints on S- and P-velocity structure, is included in the inversion, the results for density are markedly improved. The use of gravity data as an additional observable, however, deteriorates the inversion results. This is because of the significant non-uniqueness of potential field measurements, so that an unconstrained update based on gravity will only almost definitely work to push the inversion in the wrong direction.
Development of 2D SIP Data Processing Software for a Metallic Mineral Deposit Exploration
NASA Astrophysics Data System (ADS)
PARK, M.; Kim, K. S.; Seo, H. K.; Son, J.; Park, S.; Kim, C.; Kim, J. H.
2015-12-01
algorithm, we could get more reliable inversion result for the time-domain IP data. Therefore, it is expected the SIP method should be more popular if the developed 2D SIP processing software is widely used.
Frequency-domain elastic full waveform inversion using encoded simultaneous sources
NASA Astrophysics Data System (ADS)
Jeong, W.; Son, W.; Pyun, S.; Min, D.
2011-12-01
Currently, numerous studies have endeavored to develop robust full waveform inversion and migration algorithms. These processes require enormous computational costs, because of the number of sources in the survey. To avoid this problem, the phase encoding technique for prestack migration was proposed by Romero (2000) and Krebs et al. (2009) proposed the encoded simultaneous-source inversion technique in the time domain. On the other hand, Ben-Hadj-Ali et al. (2011) demonstrated the robustness of the frequency-domain full waveform inversion with simultaneous sources for noisy data changing the source assembling. Although several studies on simultaneous-source inversion tried to estimate P- wave velocity based on the acoustic wave equation, seismic migration and waveform inversion based on the elastic wave equations are required to obtain more reliable subsurface information. In this study, we propose a 2-D frequency-domain elastic full waveform inversion technique using phase encoding methods. In our algorithm, the random phase encoding method is employed to calculate the gradients of the elastic parameters, source signature estimation and the diagonal entries of approximate Hessian matrix. The crosstalk for the estimated source signature and the diagonal entries of approximate Hessian matrix are suppressed with iteration as for the gradients. Our 2-D frequency-domain elastic waveform inversion algorithm is composed using the back-propagation technique and the conjugate-gradient method. Source signature is estimated using the full Newton method. We compare the simultaneous-source inversion with the conventional waveform inversion for synthetic data sets of the Marmousi-2 model. The inverted results obtained by simultaneous sources are comparable to those obtained by individual sources, and source signature is successfully estimated in simultaneous source technique. Comparing the inverted results using the pseudo Hessian matrix with previous inversion results
Genetic polymorphisms of CYP2D6 oxidation in patients with systemic lupus erythematosus
Skrętkowicz, Jadwiga; Barańska, Małgorzata; Kaczorowska, Anna; Rychlik-Sych, Mariola
2011-01-01
Introduction Systemic lupus erythematosus (SLE) is a complex, multifactor autoimmune disease. The studies on aetiopathogenesis of autoimmune diseases focus on the impact the genetically conditioned impairment of xenobiotic metabolism may exert. The knowledge of oxidation polymorphism in the course of SLE may be helpful in choosing more efficient and safer therapy. We determined whether there was an association between susceptibility to SLE and particularly to CYP2D6 genotypes. Material and methods The study was carried out in 60 patients with SLE and 129 healthy volunteers and all the subjects were of Polish origin. The samples were analysed for two major defective alles for CYP2D6 – CYP2D6*3 and CYP2D6*4 and one wild -type allele CYP2D6*1-by the polymerase chain reaction fragment length polymorphism (PCR-RFLP) metod with DNA extracted from peripheral blood. Results No statistically significant differences in the incidence of CYP2D6 genotypes between the studied groups were found (p = 0.615). Risk (OR) of SLE development was 1.03 for the carriers of CYP2D6*3 allele and 1.48 for the subjects with CYP2D6*4 allele; but it was not statistically significant. Conclusions Increased occurrence of mutant alleles of the CYP2D6 gene in SLE patients and the calculated OR values could suggest the effect of these mutations on increased SLE development. PMID:22291833
Coupled inverse geochemical and microbial reactive transport models in porous media
NASA Astrophysics Data System (ADS)
Samper, J.; Yang, C.
2007-12-01
Microbial processes play a major role in controlling geochemical conditions in subsurface systems. Various laboratory and in situ experiments have been performed to evaluate the relevance of microbial processes and derive key microbial parameters. Such experiments are often interpreted by suboptimal trial-and-error curve fitting. Here we present an inverse model for coupled flow, reactive solute transport, geochemical and microbial processes which overcomes the limitations of trial-and-error methods by making data interpretation in a systematic, objective, and efficient manner. It extends the capabilities of existing inverse models which deal mostly with flow and chemically-reactive solute transport. Our inverse model relies on the microbial reactive transport code BIOCORE of Samper et al. (2006a) and improves the inverse reactive transport model INVERSE- CORE of Dai and Samper (2004) by allowing the simultaneous estimation of geochemical and microbial parameters. The inverse model has been implemented in a finite element code, INVERSE-BIOCORE2D and its capabilities have been verified and tested with a synthetic experiment involving equilibrium speciation, kinetic sorption/desorption and kinetic biodegradation reactions. Model results indicate that both chemical and microbial parameters can be estimated accurately for error-free data. Estimation errors of microbial parameters are larger than those of kinetic sorption parameters and generally increase with increasing standard deviation of data noise. Estimation error of yield coefficient is the smallest among all microbial parameter and which does not depend on data noise. The inverse model has been used also to estimate microbial parameters of a laboratory experiment involving sucrose fermentation by yeast. Inverse estimation improves significantly the fit to measured data.
NASA Astrophysics Data System (ADS)
Cheng, Chingyun; Kangara, Jayampathi; Arakelyan, Ilya; Thomas, John
2016-05-01
We tune the dimensionality of a strongly interacting degenerate 6 Li Fermi gas from 2D to quasi-2D, by adjusting the radial confinement of pancake-shaped clouds to control the radial chemical potential. In the 2D regime with weak radial confinement, the measured pair binding energies are in agreement with 2D-BCS mean field theory, which predicts dimer pairing energies in the many-body regime. In the qausi-2D regime obtained with increased radial confinement, the measured pairing energy deviates significantly from 2D-BCS theory. In contrast to the pairing energy, the measured radii of the cloud profiles are not fit by 2D-BCS theory in either the 2D or quasi-2D regimes, but are fit in both regimes by a beyond mean field polaron-model of the free energy. Supported by DOE, ARO, NSF, and AFOSR.
Thermopower enhancement by fractional layer control in 2D oxide superlattices.
Choi, Woo Seok; Ohta, Hiromichi; Lee, Ho Nyung
2014-10-22
Precise tuning of the 2D carrier density by using fractional δ-doping of d electrons improves the thermoelectric properties of oxide heterostructures. This promising result can be attributed to the anisotropic band structure in the 2D system, indicating that δ-doped oxide superlattices are good candidates for advanced thermoelectrics.
Competing coexisting phases in 2D water
Zanotti, Jean-Marc; Judeinstein, Patrick; Dalla-Bernardina, Simona; Creff, Gaëlle; Brubach, Jean-Blaise; Roy, Pascale; Bonetti, Marco; Ollivier, Jacques; Sakellariou, Dimitrios; Bellissent-Funel, Marie-Claire
2016-01-01
The properties of bulk water come from a delicate balance of interactions on length scales encompassing several orders of magnitudes: i) the Hydrogen Bond (HBond) at the molecular scale and ii) the extension of this HBond network up to the macroscopic level. Here, we address the physics of water when the three dimensional extension of the HBond network is frustrated, so that the water molecules are forced to organize in only two dimensions. We account for the large scale fluctuating HBond network by an analytical mean-field percolation model. This approach provides a coherent interpretation of the different events experimentally (calorimetry, neutron, NMR, near and far infra-red spectroscopies) detected in interfacial water at 160, 220 and 250 K. Starting from an amorphous state of water at low temperature, these transitions are respectively interpreted as the onset of creation of transient low density patches of 4-HBonded molecules at 160 K, the percolation of these domains at 220 K and finally the total invasion of the surface by them at 250 K. The source of this surprising behaviour in 2D is the frustration of the natural bulk tetrahedral local geometry and the underlying very significant increase in entropy of the interfacial water molecules. PMID:27185018
Competing coexisting phases in 2D water
NASA Astrophysics Data System (ADS)
Zanotti, Jean-Marc; Judeinstein, Patrick; Dalla-Bernardina, Simona; Creff, Gaëlle; Brubach, Jean-Blaise; Roy, Pascale; Bonetti, Marco; Ollivier, Jacques; Sakellariou, Dimitrios; Bellissent-Funel, Marie-Claire
2016-05-01
The properties of bulk water come from a delicate balance of interactions on length scales encompassing several orders of magnitudes: i) the Hydrogen Bond (HBond) at the molecular scale and ii) the extension of this HBond network up to the macroscopic level. Here, we address the physics of water when the three dimensional extension of the HBond network is frustrated, so that the water molecules are forced to organize in only two dimensions. We account for the large scale fluctuating HBond network by an analytical mean-field percolation model. This approach provides a coherent interpretation of the different events experimentally (calorimetry, neutron, NMR, near and far infra-red spectroscopies) detected in interfacial water at 160, 220 and 250 K. Starting from an amorphous state of water at low temperature, these transitions are respectively interpreted as the onset of creation of transient low density patches of 4-HBonded molecules at 160 K, the percolation of these domains at 220 K and finally the total invasion of the surface by them at 250 K. The source of this surprising behaviour in 2D is the frustration of the natural bulk tetrahedral local geometry and the underlying very significant increase in entropy of the interfacial water molecules.
Probabilistic inversion in the context of EM studies: Where we are and avenues for the future
NASA Astrophysics Data System (ADS)
Linde, Niklas; Rosas-Carbajal, Marina
2016-04-01
Modern Markov chain Monte Carlo (MCMC) algorithms can explore the posterior distribution of highly non-linear inverse problems in moderately high dimensions. For instance, 2-D magnetotelluric inversion is feasible for several hundreds of independent model parameters. At present, 3-D applications are limited to a few tenths of model parameters, but even such low dimensions make MCMC useful in time-lapse inversions when using appropriate model parameterizations. It is straightforward to invert for the noise level of the data (i.e., hierarchical Bayes) and the appropriate strength of the prior constraints (i.e., empirical Bayes). It is even possible to consider the dimension of the problem as an unknown (i.e., reversible-jump or transdimensional inversion). Nevertheless, persistent problems that plague MCMC inversions in geophysics include the choice of the prior probability density function, overly simplistic descriptions of data and modeling errors in the likelihood function, as well as truncation errors or spectral leakage that are inevitable when describing the Earth by a finite number of parameters. This leads to uncertainty estimates that often are overly optimistic (or alternatively limited by a too restrictive set of hypotheses) and final results that at times are only vaguely more informative than those obtained by classical Occam inversions. We argue that formal model selection, multiple-point statistics and approximate Bayesian computation may offer solutions to overcome some of these outstanding issues.
3-D full waveform inversion of seismic data; Part I. Theory
Lee, Ki Ha
2003-05-12
Full waveform inversion of seismic data is a challenging subject partly because of the lack of precise knowledge of the source. Since currently available approaches involve some form of approximations to the source, inversion results are subject to the quality and the choice of the source information used. A new full waveform inversion scheme has been introduced (Lee and Kim, 2003) using normalized wavefield for simple two-dimensional (2-D) scalar problems. The method does not require source information, so potential inversion errors due to source estimation may be eliminated. A gather of seismic traces is first Fourier-transformed into the frequency domain and a normalized wavefield is obtained for each trace in the frequency domain. Normalization is done with respect to the frequency response of a reference trace selected from the gather, so the complex-valued normalized wavefield is source-independent and dimensionless. The inversion algorithm minimizes misfits between measured normalized wavefield and numerically computed normalized wavefield. In this paper the full waveform inversion is extended to three-dimensional (3-D) problems.
PARCEQ2D heat transfer grid sensitivity analysis
Saladino, A.J.; Praharaj, S.C.; Collins, F.G. Tennessee Univ., Tullahoma )
1991-01-01
The material presented in this paper is an extension of two-dimensional Aeroassist Flight Experiment (AFE) results shown previously. This study has focused on the heating rate calculations to the AFE obtained from an equilibrium real gas code, with attention placed on the sensitivity of grid dependence and wall temperature. Heat transfer results calculated by the PARCEQ2D code compare well with those computed by other researchers. Temperature convergence in the case of kinetic transport has been accomplished by increasing the wall temperature gradually from 300 K to the wall temperature of 1700 K. 28 refs.
PARCEQ2D heat transfer grid sensitivity analysis
NASA Technical Reports Server (NTRS)
Saladino, Anthony J.; Praharaj, Sarat C.; Collins, Frank G.
1991-01-01
The material presented in this paper is an extension of two-dimensional Aeroassist Flight Experiment (AFE) results shown previously. This study has focused on the heating rate calculations to the AFE obtained from an equilibrium real gas code, with attention placed on the sensitivity of grid dependence and wall temperature. Heat transfer results calculated by the PARCEQ2D code compare well with those computed by other researchers. Temperature convergence in the case of kinetic transport has been accomplished by increasing the wall temperature gradually from 300 K to the wall temperature of 1700 K.
Finite Element Analysis of 2-D Elastic Contacts Involving FGMs
NASA Astrophysics Data System (ADS)
Abhilash, M. N.; Murthy, H.
2014-05-01
The response of elastic indenters in contact with Functionally Graded Material (FGM) coated homogeneous elastic half space has been presented in the current paper. Finite element analysis has been used due to its ability to handle complex geometry, material, and boundary conditions. Indenters of different typical surface profiles have been considered and the problem has been idealized as a two-dimensional (2D) plane strain problem considering only normal loads. Initially, indenters were considered to be rigid and the results were validated with the solutions presented in the literature. The analysis has then been extended to the case of elastic indenters on FGM-coated half spaces and the results are discussed.
Inverse heat conduction problems
NASA Astrophysics Data System (ADS)
Orlande, Helcio Rangel Barreto
solve the inverse problem of estimating the thermal diffusivity and the relaxation time with a hyperbolic heat conduction model. Levenberg-Marquardt's Method of minimization was utilized and results obtained with simulated measurements revealed that the method provides accurate estimates for the unknown parameters.
Rapid approximate inversion of airborne TEM
NASA Astrophysics Data System (ADS)
Fullagar, Peter K.; Pears, Glenn A.; Reid, James E.; Schaa, Ralf
2015-11-01
Rapid interpretation of large airborne transient electromagnetic (ATEM) datasets is highly desirable for timely decision-making in exploration. Full solution 3D inversion of entire airborne electromagnetic (AEM) surveys is often still not feasible on current day PCs. Therefore, two algorithms to perform rapid approximate 3D interpretation of AEM have been developed. The loss of rigour may be of little consequence if the objective of the AEM survey is regional reconnaissance. Data coverage is often quasi-2D rather than truly 3D in such cases, belying the need for `exact' 3D inversion. Incorporation of geological constraints reduces the non-uniqueness of 3D AEM inversion. Integrated interpretation can be achieved most readily when inversion is applied to a geological model, attributed with lithology as well as conductivity. Geological models also offer several practical advantages over pure property models during inversion. In particular, they permit adjustment of geological boundaries. In addition, optimal conductivities can be determined for homogeneous units. Both algorithms described here can operate on geological models; however, they can also perform `unconstrained' inversion if the geological context is unknown. VPem1D performs 1D inversion at each ATEM data location above a 3D model. Interpretation of cover thickness is a natural application; this is illustrated via application to Spectrem data from central Australia. VPem3D performs 3D inversion on time-integrated (resistive limit) data. Conversion to resistive limits delivers a massive increase in speed since the TEM inverse problem reduces to a quasi-magnetic problem. The time evolution of the decay is lost during the conversion, but the information can be largely recovered by constructing a starting model from conductivity depth images (CDIs) or 1D inversions combined with geological constraints if available. The efficacy of the approach is demonstrated on Spectrem data from Brazil. Both separately and in
2-D Animation's Not Just for Mickey Mouse.
ERIC Educational Resources Information Center
Weinman, Lynda
1995-01-01
Discusses characteristics of two-dimensional (2-D) animation; highlights include character animation, painting issues, and motion graphics. Sidebars present Silicon Graphics animations tools and 2-D animation programs for the desktop computer. (DGM)
New Spatiotemporal Approaches for Fully-Refocused, Multi-Slice Ultrafast 2D MRI
Schmidt, Rita; Frydman, Lucio
2016-01-01
Purpose Single-scan multi-slice acquisition schemes play key roles in MRI. Central among these “ultrafast” experiments stands EPI, a technique that although of optimal sampling is challenged by T2* artifacts. Recent studies described alternatives based on spatiotemporal encoding (SPEN), which are particularly robust if implemented in a “full-refocusing” mode. The present work extends this modality from the single-slice acquisitions in which it has hitherto been implemented, by introducing a variety of multi-slice schemes scanning 3D volumes. Methods Multi-slice SPEN employing either inversion or stimulated echo pulses and timed to fulfill the demands of full-refocusing, are demonstrated. The performance of the ensuing methods was examined in “Hybrid” modalities encoding data in k- and direct-space, in low-SAR stimulated-echo approaches, and in direct-space SPEN approaches. Results When applied in phantoms and in in vivo systems, the ensuing single-shot sequences evidenced similar robustness, sensitivity and resolution qualities as previously discussed 2D single-slice schemes –while enabling a rapid sampling of the third dimension via multi-slicing. Conclusion The unique benefits deriving from fully-refocused, multi-slice, single-scan SPEN sequences were corroborated by phantom tests, as well as by in vivo scans at 3T and 7T. Low SAR multi-slice SPEN variants compatible with human studies were demonstrated. PMID:23468061
Chmelík, M; Kukurová, I Just; Gruber, S; Krššák, M; Valkovič, L; Trattnig, S; Bogner, W
2013-05-01
A fully adiabatic phosphorus (31P) two-dimensional (2D) chemical shift spectroscopic imaging sequence with reduced chemical shift displacement error for 7 T, based on 1D-image-selected in vivo spectroscopy, combined with 2D-chemical shift spectroscopic imaging selection, was developed. Slice-selective excitation was achieved by a spatially selective broadband GOIA-W(16,4) inversion pulse with an interleaved subtraction scheme before nonselective adiabatic excitation, and followed by 2D phase encoding. The use of GOIA-W(16,4) pulses (bandwidth 4.3-21.6 kHz for 10-50 mm slices) reduced the chemical shift displacement error in the slice direction ∼1.5-7.7 fold, compared to conventional 2D-chemical shift spectroscopic imaging with Sinc3 selective pulses (2.8 kHz). This reduction was experimentally demonstrated with measurements of an MR spectroscopy localization phantom and with experimental evaluation of pulse profiles. In vivo experiments in clinically acceptable measurement times were demonstrated in the calf muscle (nominal voxel volume, 5.65 ml in 6 min 53 s), brain (10 ml, 6 min 32 s), and liver (8.33 ml, 8 min 14 s) of healthy volunteers at 7 T. High reproducibility was found in the calf muscle at 7 T. In combination with adiabatic excitation, this sequence is insensitive to the B1 inhomogeneities associated with surface coils. This sequence, which is termed GOIA-1D-ISIS/2D-CSI (goISICS), has the potential to be applied in both clinical research and in the clinical routine.
Generates 2D Input for DYNA NIKE & TOPAZ
Hallquist, J. O.; Sanford, Larry
1996-07-15
MAZE is an interactive program that serves as an input and two-dimensional mesh generator for DYNA2D, NIKE2D, TOPAZ2D, and CHEMICAL TOPAZ2D. MAZE also generates a basic template for ISLAND input. MAZE has been applied to the generation of input data to study the response of two-dimensional solids and structures undergoing finite deformations under a wide variety of large deformation transient dynamic and static problems and heat transfer analyses.
MAZE96. Generates 2D Input for DYNA NIKE & TOPAZ
Sanford, L.; Hallquist, J.O.
1992-02-24
MAZE is an interactive program that serves as an input and two-dimensional mesh generator for DYNA2D, NIKE2D, TOPAZ2D, and CHEMICAL TOPAZ2D. MAZE also generates a basic template for ISLAND input. MAZE has been applied to the generation of input data to study the response of two-dimensional solids and structures undergoing finite deformations under a wide variety of large deformation transient dynamic and static problems and heat transfer analyses.
Temperature inversion in China seas
NASA Astrophysics Data System (ADS)
Hao, Jiajia; Chen, Yongli; Wang, Fan
2010-12-01
Temperature inversion was reported as a common phenomenon in the areas near the southeastern Chinese coast (region A), west and south of the Korean Peninsula (region B), and north and east of the Shandong Peninsula (region C) during October-May in the present study, based on hydrographic data archived from 1930 through 2001 (319,029 profiles). The inversion was found to be remarkable with obvious temporal and spatial variabilities in both magnitude and coverage, with higher probabilities in region A (up to about 60%) and region C (40%-50%) than in region B (15%-20%). The analysis shows that seasonal variation of the net air-sea heat flux is closely related to the occurrence time of the inversion in the three areas, while the Yangtze and Yellow river freshwater plumes in the surface layer and ocean origin saline water in the subsurface layer maintain stable stratification. It seems that the evaporation/excessive precipitation flux makes little contribution to maintaining the stable inversion. Advection of surface fresh water by the wind-driven coastal currents results in the expansion of inversion in regions A and C. The inversion lasts for the longest period in region A (October-May) sustained by the Taiwan Warm Current carrying the subsurface saline water, while evolution of the inversion in region B is mainly controlled by the Yellow Sea Warm Current.
Position control using 2D-to-2D feature correspondences in vision guided cell micromanipulation.
Zhang, Yanliang; Han, Mingli; Shee, Cheng Yap; Ang, Wei Tech
2007-01-01
Conventional camera calibration that utilizes the extrinsic and intrinsic parameters of the camera and the objects has certain limitations for micro-level cell operations due to the presence of hardware deviations and external disturbances during the experimental process, thereby invalidating the extrinsic parameters. This invalidation is often neglected in macro-world visual servoing and affects the visual image processing quality, causing deviation from the desired position in micro-level cell operations. To increase the success rate of vision guided biological micromanipulations, a novel algorithm monitoring the changing image pattern of the manipulators including the injection micropipette and cell holder is designed and implemented based on 2 dimensional (2D)-to 2D feature correspondences and can adjust the manipulator and perform position control simultaneously. When any deviation is found, the manipulator is retracted to the initial focusing plane before continuing the operation.
Wang, Zenghui; Feng, Philip X-L
2016-01-01
Atomic layer crystals are emerging building blocks for enabling new two-dimensional (2D) nanomechanical systems, whose motions can be coupled to other attractive physical properties in such 2D systems. Optical interferometry has been very effective in reading out the infinitesimal motions of these 2D structures and spatially resolving different modes. To quantitatively understand the detection efficiency and its dependence on the device parameters and interferometric conditions, here we present a systematic study of the intrinsic motion responsivity in 2D nanomechanical systems using a Fresnel-law-based model. We find that in monolayer to 14-layer structures, MoS2 offers the highest responsivity among graphene, h-BN, and MoS2 devices and for the three commonly used visible laser wavelengths (633, 532, and 405 nm). We also find that the vacuum gap resulting from the widely used 300 nm-oxide substrate in making 2D devices, fortunately, leads to close-to-optimal responsivity for a wide range of 2D flakes. Our results elucidate and graphically visualize the dependence of motion transduction responsivity upon 2D material type and number of layers, vacuum gap, oxide thickness, and detecting wavelength, thus providing design guidelines for constructing 2D nanomechanical systems with optimal optical motion readout. PMID:27464908
Wang, Zenghui; Feng, Philip X-L
2016-07-28
Atomic layer crystals are emerging building blocks for enabling new two-dimensional (2D) nanomechanical systems, whose motions can be coupled to other attractive physical properties in such 2D systems. Optical interferometry has been very effective in reading out the infinitesimal motions of these 2D structures and spatially resolving different modes. To quantitatively understand the detection efficiency and its dependence on the device parameters and interferometric conditions, here we present a systematic study of the intrinsic motion responsivity in 2D nanomechanical systems using a Fresnel-law-based model. We find that in monolayer to 14-layer structures, MoS2 offers the highest responsivity among graphene, h-BN, and MoS2 devices and for the three commonly used visible laser wavelengths (633, 532, and 405 nm). We also find that the vacuum gap resulting from the widely used 300 nm-oxide substrate in making 2D devices, fortunately, leads to close-to-optimal responsivity for a wide range of 2D flakes. Our results elucidate and graphically visualize the dependence of motion transduction responsivity upon 2D material type and number of layers, vacuum gap, oxide thickness, and detecting wavelength, thus providing design guidelines for constructing 2D nanomechanical systems with optimal optical motion readout.
NASA Astrophysics Data System (ADS)
Wang, Zenghui; Feng, Philip X.-L.
2016-07-01
Atomic layer crystals are emerging building blocks for enabling new two-dimensional (2D) nanomechanical systems, whose motions can be coupled to other attractive physical properties in such 2D systems. Optical interferometry has been very effective in reading out the infinitesimal motions of these 2D structures and spatially resolving different modes. To quantitatively understand the detection efficiency and its dependence on the device parameters and interferometric conditions, here we present a systematic study of the intrinsic motion responsivity in 2D nanomechanical systems using a Fresnel-law-based model. We find that in monolayer to 14-layer structures, MoS2 offers the highest responsivity among graphene, h-BN, and MoS2 devices and for the three commonly used visible laser wavelengths (633, 532, and 405 nm). We also find that the vacuum gap resulting from the widely used 300 nm-oxide substrate in making 2D devices, fortunately, leads to close-to-optimal responsivity for a wide range of 2D flakes. Our results elucidate and graphically visualize the dependence of motion transduction responsivity upon 2D material type and number of layers, vacuum gap, oxide thickness, and detecting wavelength, thus providing design guidelines for constructing 2D nanomechanical systems with optimal optical motion readout.
Wang, Zenghui; Feng, Philip X.-L.
2016-01-01
Atomic layer crystals are emerging building blocks for enabling new two-dimensional (2D) nanomechanical systems, whose motions can be coupled to other attractive physical properties in such 2D systems. Optical interferometry has been very effective in reading out the infinitesimal motions of these 2D structures and spatially resolving different modes. To quantitatively understand the detection efficiency and its dependence on the device parameters and interferometric conditions, here we present a systematic study of the intrinsic motion responsivity in 2D nanomechanical systems using a Fresnel-law-based model. We find that in monolayer to 14-layer structures, MoS2 offers the highest responsivity among graphene, h-BN, and MoS2 devices and for the three commonly used visible laser wavelengths (633, 532, and 405 nm). We also find that the vacuum gap resulting from the widely used 300 nm-oxide substrate in making 2D devices, fortunately, leads to close-to-optimal responsivity for a wide range of 2D flakes. Our results elucidate and graphically visualize the dependence of motion transduction responsivity upon 2D material type and number of layers, vacuum gap, oxide thickness, and detecting wavelength, thus providing design guidelines for constructing 2D nanomechanical systems with optimal optical motion readout. PMID:27464908
A Planar Quantum Transistor Based on 2D-2D Tunneling in Double Quantum Well Heterostructures
Baca, W.E.; Blount, M.A.; Hafich, M.J.; Lyo, S.K.; Moon, J.S.; Reno, J.L.; Simmons, J.A.; Wendt, J.R.
1998-12-14
We report on our work on the double electron layer tunneling transistor (DELTT), based on the gate-control of two-dimensional -- two-dimensional (2D-2D) tunneling in a double quantum well heterostructure. While previous quantum transistors have typically required tiny laterally-defined features, by contrast the DELTT is entirely planar and can be reliably fabricated in large numbers. We use a novel epoxy-bond-and-stop-etch (EBASE) flip-chip process, whereby submicron gating on opposite sides of semiconductor epitaxial layers as thin as 0.24 microns can be achieved. Because both electron layers in the DELTT are 2D, the resonant tunneling features are unusually sharp, and can be easily modulated with one or more surface gates. We demonstrate DELTTs with peak-to-valley ratios in the source-drain I-V curve of order 20:1 below 1 K. Both the height and position of the resonant current peak can be controlled by gate voltage over a wide range. DELTTs with larger subband energy offsets ({approximately} 21 meV) exhibit characteristics that are nearly as good at 77 K, in good agreement with our theoretical calculations. Using these devices, we also demonstrate bistable memories operating at 77 K. Finally, we briefly discuss the prospects for room temperature operation, increases in gain, and high-speed.
Inhibition of human cytochrome P450 2D6 (CYP2D6) by methadone.
Wu, D; Otton, S V; Sproule, B A; Busto, U; Inaba, T; Kalow, W; Sellers, E M
1993-01-01
1. In microsomes prepared from three human livers, methadone competitively inhibited the O-demethylation of dextromethorphan, a marker substrate for CYP2D6. The apparent Ki value of methadone ranged from 2.5 to 5 microM. 2. Two hundred and fifty-two (252) white Caucasians, including 210 unrelated healthy volunteers and 42 opiate abusers undergoing treatment with methadone were phenotyped using dextromethorphan as the marker drug. Although the frequency of poor metabolizers was similar in both groups, the extensive metabolizers among the opiate abusers tended to have higher O-demethylation metabolic ratios and to excrete less of the dose as dextromethorphan metabolites than control extensive metabolizer subjects. These data suggest inhibition of CYP2D6 by methadone in vivo as well. 3. Because methadone is widely used in the treatment of opiate abuse, inhibition of CYP2D6 activity in these patients might contribute to exaggerated response or unexpected toxicity from drugs that are substrates of this enzyme. PMID:8448065
NASA Astrophysics Data System (ADS)
Lacava, C.; Carrol, L.; Bozzola, A.; Marchetti, R.; Minzioni, P.; Cristiani, I.; Fournier, M.; Bernabe, S.; Gerace, D.; Andreani, L. C.
2016-03-01
We present the characterization of Silicon-on-insulator (SOI) photonic-crystal based 2D grating-couplers (2D-GCs) fabricated by CEA-Leti in the frame of the FP7 Fabulous project, which is dedicated to the realization of devices and systems for low-cost and high-performance passives-optical-networks. On the analyzed samples different test structures are present, including 2D-GC connected to another 2D-GC by different waveguides (in a Mach-Zehnder like configuration), and 2D-GC connected to two separate 2D-GCs, so as to allow a complete assessment of different parameters. Measurements were carried out using a tunable laser source operating in the extended telecom bandwidth and a fiber-based polarization controlling system at the input of device-under-test. The measured data yielded an overall fiber-to-fiber loss of 7.5 dB for the structure composed by an input 2D-GC connected to two identical 2D-GCs. This value was obtained at the peak wavelength of the grating, and the 3-dB bandwidth of the 2D-GC was assessed to be 43 nm. Assuming that the waveguide losses are negligible, so as to make a worst-case analysis, the coupling efficiency of the single 2D-GC results to be equal to -3.75 dB, constituting, to the best of our knowledge, the lowest value ever reported for a fully CMOS compatible 2D-GC. It is worth noting that both the obtained values are in good agreement with those expected by the numerical simulations performed using full 3D analysis by Lumerical FDTD-solutions.
3D Inversion of complex resistivity data: Case study on Mineral Exploration Site.
NASA Astrophysics Data System (ADS)
Son, Jeong-Sul; Kim, Jung-ho; Park, Sam-gyu; Park, My-Kyung
2016-04-01
Complex resistivity (CR) method is a frequency domain induced polarization (IP) method. It is also known as Spectral IP (SIP) method, if wider frequencies are used in data acquisition and interpretation. Although it takes more times than conventional time domain IP method, its data quality is more stable because its data acquisition which measures amplitude and phase is done when the source current is being injected. Our research group has been studying the modeling and inversion algorithms of complex resistivity (CR) method since several years ago and recently applied developed algorithms to various real field application. Due to tough terrain in our country, Profile survey and 2D interpretation were generally used. But to get more precise interpretation, three dimensional modeling and inversion algorithm is required. We developed three dimensional inversion algorithm for this purpose. In the inversion, we adopt the method of adaptive lagraingian multiplier which is automatically set based on the size of error misfit and model regularization norm. It was applied on the real data acquired for mineral exploration sites. CR data was acquired with the Zeta system, manufactured by Zonge Co. In the inversion, only the lower frequency data is used considering its quality and developed 3D inversion algorithm was applied to the acquired data set. Its results were compared to those of time domain IP data conducted at the same site. Resistivity image sections of CR and conventional resistivity method were almost identical. Phase anomalies were well matched with chargeability anomalies and the mining history of the test site. Each anomalies were well discriminated in 3D interpretation than those of 2D. From those experiments, we know that CR method was very effective for the mineral exploration.
Topology-Preserving Rigid Transformation of 2D Digital Images.
Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues
2014-02-01
We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping.
Quantum Oscillations in an Interfacial 2D Electron Gas.
Zhang, Bingop; Lu, Ping; Liu, Henan; Lin, Jiao; Ye, Zhenyu; Jaime, Marcelo; Balakirev, Fedor F.; Yuan, Huiqiu; Wu, Huizhen; Pan, Wei; Zhang, Yong
2016-01-01
Recently, it has been predicted that topological crystalline insulators (TCIs) may exist in SnTe and Pb_{1-x}Sn_{x}Te thin films [1]. To date, most studies on TCIs were carried out either in bulk crystals or thin films, and no research activity has been explored in heterostructures. We present here the results on electronic transport properties of the 2D electron gas (2DEG) realized at the interfaces of PbTe/ CdTe (111) heterostructures. Evidence of topological state in this interfacial 2DEG was observed.
The 2d MIT: The Pseudogap and Fermi Liquid Theory
NASA Astrophysics Data System (ADS)
Castner, T. G.
2005-06-01
Fermi liquid theory for the 2d metal-insulator transition is extended to include the correlation gap in the density-of-states. The results are consistent with the scaling form g=gce[on(To/T)] at T larger than a characteristic T* ∝ xTc (Tc=Ec= mobility edge). The two-component model n1+nloc=n=nc(1+x) for n>nc is required and the theory explains the T-dependence of the data of Hanein et al. for p-type GaAs.
Anomalous Hall Effect in a 2D Rashba Ferromagnet
NASA Astrophysics Data System (ADS)
Ado, I. A.; Dmitriev, I. A.; Ostrovsky, P. M.; Titov, M.
2016-07-01
Skew scattering on rare impurity configurations is shown to dominate the anomalous Hall effect in a 2D Rashba ferromagnet. The mechanism originates in scattering on rare impurity pairs separated by distances of the order of the Fermi wavelength. The corresponding theoretical description goes beyond the conventional noncrossing approximation. The mechanism provides the only contribution to the anomalous Hall conductivity in the most relevant metallic regime and strongly modifies previously obtained results for lower energies in the leading order with respect to impurity strength.
Topology-Preserving Rigid Transformation of 2D Digital Images.
Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues
2014-02-01
We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping. PMID:26270925
A parallel splitting wavelet method for 2D conservation laws
NASA Astrophysics Data System (ADS)
Schmidt, Alex A.; Kozakevicius, Alice J.; Jakobsson, Stefan
2016-06-01
The current work presents a parallel formulation using the MPI protocol for an adaptive high order finite difference scheme to solve 2D conservation laws. Adaptivity is achieved at each time iteration by the application of an interpolating wavelet transform in each space dimension. High order approximations for the numerical fluxes are computed by ENO and WENO schemes. Since time evolution is made by a TVD Runge-Kutta space splitting scheme, the problem is naturally suitable for parallelization. Numerical simulations and speedup results are presented for Euler equations in gas dynamics problems.
Conformal field theory of critical Casimir interactions in 2D
NASA Astrophysics Data System (ADS)
Bimonte, G.; Emig, T.; Kardar, M.
2013-10-01
Thermal fluctuations of a critical system induce long-ranged Casimir forces between objects that couple to the underlying field. For two-dimensional (2D) conformal field theories (CFT) we derive an exact result for the Casimir interaction between two objects of arbitrary shape, in terms of 1) the free energy of a circular ring whose radii are determined by the mutual capacitance of two conductors with the objects' shape; and 2) a purely geometric energy that is proportional to the conformal charge of the CFT, but otherwise super-universal in that it depends only on the shapes and is independent of boundary conditions and other details.
A unified viscous theory of lift and drag of 2-D thin airfoils and 3-D thin wings
NASA Technical Reports Server (NTRS)
Yates, John E.
1991-01-01
A unified viscous theory of 2-D thin airfoils and 3-D thin wings is developed with numerical examples. The viscous theory of the load distribution is unique and tends to the classical inviscid result with Kutta condition in the high Reynolds number limit. A new theory of 2-D section induced drag is introduced with specific applications to three cases of interest: (1) constant angle of attack; (2) parabolic camber; and (3) a flapped airfoil. The first case is also extended to a profiled leading edge foil. The well-known drag due to absence of leading edge suction is derived from the viscous theory. It is independent of Reynolds number for zero thickness and varies inversely with the square root of the Reynolds number based on the leading edge radius for profiled sections. The role of turbulence in the section induced drag problem is discussed. A theory of minimum section induced drag is derived and applied. For low Reynolds number the minimum drag load tends to the constant angle of attack solution and for high Reynolds number to an approximation of the parabolic camber solution. The parabolic camber section induced drag is about 4 percent greater than the ideal minimum at high Reynolds number. Two new concepts, the viscous induced drag angle and the viscous induced separation potential are introduced. The separation potential is calculated for three 2-D cases and for a 3-D rectangular wing. The potential is calculated with input from a standard doublet lattice wing code without recourse to any boundary layer calculations. Separation is indicated in regions where it is observed experimentally. The classical induced drag is recovered in the 3-D high Reynolds number limit with an additional contribution that is Reynold number dependent. The 3-D viscous theory of minimum induced drag yields an equation for the optimal spanwise and chordwise load distribution. The design of optimal wing tip planforms and camber distributions is possible with the viscous 3-D wing theory.
2D Potential theory using complex functions and conformal mapping
NASA Astrophysics Data System (ADS)
Le Maire, Pauline; Munschy, Marc
2016-04-01
For infinitely horizontally extended bodies, functions that describe potential and field equations (gravity and magnetics) outside bodies are 2D and harmonic. The consequence of this property is that potential and field equations can be written as complex analytic functions. We define these complex functions whose real part is the commonly used real function and imaginary part is its Hilbert transform. Using data or synthetic cases the transformation is easily performed in the Fourier domain by setting to zero all values for negative frequencies. Written as complex functions of the complex variable, equations of potential and field in gravity and magnetics for different kinds of geometries are simple and correspond to powers of the inverse of the distance. For example, it is easily shown that for a tilted dyke, the dip and the apparent inclination have the same effect on the function and consequently that it is not possible, with data, to compute one of both values without knowing the other. Conformal mapping is an original way to display potential field functions. Considering that the complex variable corresponds to the real axis, complex potential field functions resume to a limaçon, a curve formed by the path of the point fixed to a circle when that circle rolls around the outside of another circle. For example, the point corresponding to the maximum distance to the origin of the complex magnetic field due to a cylinder, corresponds to the maximum of the analytic signal as defined by Nabighan in 1972 and its phase corresponds to the apparent inclination. Several applications are shown in different geological contexts using aeromagnetic data.
Recombination rate predicts inversion size in Diptera.
Cáceres, M; Barbadilla, A; Ruiz, A
1999-09-01
Most species of the Drosophila genus and other Diptera are polymorphic for paracentric inversions. A common observation is that successful inversions are of intermediate size. We test here the hypothesis that the selected property is the recombination length of inversions, not their physical length. If so, physical length of successful inversions should be negatively correlated with recombination rate across species. This prediction was tested by a comprehensive statistical analysis of inversion size and recombination map length in 12 Diptera species for which appropriate data are available. We found that (1) there is a wide variation in recombination map length among species; (2) physical length of successful inversions varies greatly among species and is inversely correlated with the species recombination map length; and (3) neither the among-species variation in inversion length nor the correlation are observed in unsuccessful inversions. The clear differences between successful and unsuccessful inversions point to natural selection as the most likely explanation for our results. Presumably the selective advantage of an inversion increases with its length, but so does its detrimental effect on fertility due to double crossovers. Our analysis provides the strongest and most extensive evidence in favor of the notion that the adaptive value of inversions stems from their effect on recombination.
Recombination rate predicts inversion size in Diptera.
Cáceres, M; Barbadilla, A; Ruiz, A
1999-01-01
Most species of the Drosophila genus and other Diptera are polymorphic for paracentric inversions. A common observation is that successful inversions are of intermediate size. We test here the hypothesis that the selected property is the recombination length of inversions, not their physical length. If so, physical length of successful inversions should be negatively correlated with recombination rate across species. This prediction was tested by a comprehensive statistical analysis of inversion size and recombination map length in 12 Diptera species for which appropriate data are available. We found that (1) there is a wide variation in recombination map length among species; (2) physical length of successful inversions varies greatly among species and is inversely correlated with the species recombination map length; and (3) neither the among-species variation in inversion length nor the correlation are observed in unsuccessful inversions. The clear differences between successful and unsuccessful inversions point to natural selection as the most likely explanation for our results. Presumably the selective advantage of an inversion increases with its length, but so does its detrimental effect on fertility due to double crossovers. Our analysis provides the strongest and most extensive evidence in favor of the notion that the adaptive value of inversions stems from their effect on recombination. PMID:10471710
Repression of multiple CYP2D genes in mouse primary hepatocytes with a single siRNA construct.
Elraghy, Omaima; Baldwin, William S
2015-01-01
The Cyp2d subfamily is the second most abun-dant subfamily of hepatic drug-metabolizing CYPs. In mice, there are nine Cyp2d members that are believed to have redundant catalytic activity. We are testing and optimizing the ability of one short interfering RNA (siRNA) construct to knockdown the expression of multiple mouse Cyp2ds in primary hepatocytes. Expression of Cyp2d10, Cyp2d11, Cyp2d22, and Cyp2d26 was observed in the primary male mouse hepatocytes. Cyp2d9, which is male-specific and growth hormone-dependent, was not expressed in male primary hepatocytes, potentially because of its dependence on pulsatile growth hormone release from the anterior pituitary. Several different siRNAs at different concentrations and with different reagents were used to knockdown Cyp2d expression. siRNA constructs designed to repress only one construct often mildly repressed several Cyp2d isoforms. A construct designed to knockdown every Cyp2d isoform provided the best results, especially when incubated with transfection reagents designed specifically for primary cell culture. Interestingly, a construct designed to knockdown all Cyp2d isoforms, except Cyp2d10, caused a 2.5× increase in Cyp2d10 expression, presumably because of a compensatory response. However, while RNA expression is repressed 24 h after siRNA treatment, associated changes in Cyp2d-mediated metabolism are tenuous. Overall, this study provides data on the expression of murine Cyp2ds in primary cell lines, valuable information on designing siRNAs for silencing multiple murine CYPs, and potential pros and cons of using siRNA as a tool for repressing Cyp2d and estimating Cyp2d's role in murine xenobiotic metabolism. PMID:25124873
Pan, Xian; Lee, Yoon-Kwang; Jeong, Hyunyoung
2015-07-01
Cytochrome P450 2D6 (CYP2D6) is a major drug-metabolizing enzyme responsible for eliminating approximately 20% of marketed drugs. Studies have shown that differential transcriptional regulation of CYP2D6 may contribute to large interindividual variability in CYP2D6-mediated drug metabolism. However, the factors governing CYP2D6 transcription are largely unknown. We previously demonstrated small heterodimer partner (SHP) as a novel transcriptional repressor of CYP2D6 expression. SHP is a representative target gene of the farnesoid X receptor (FXR). The objective of this study is to investigate whether an agonist of FXR, 3-(2,6-dichlorophenyl)-4-(3'-carboxy-2-chlorostilben-4-yl)oxymethyl-5-isopropylisoxazole (GW4064), alters CYP2D6 expression and activity. In CYP2D6-humanized transgenic mice, GW4064 decreased hepatic CYP2D6 expression and activity (by 2-fold) while increasing SHP expression (by 2-fold) and SHP recruitment to the CYP2D6 promoter. CYP2D6 repression by GW4064 was abrogated in Shp(-/-);CYP2D6 mice, indicating a critical role of SHP in CYP2D6 regulation by GW4064. Also, GW4064 decreased CYP2D6 expression (by 2-fold) in primary human hepatocytes, suggesting that the results obtained in CYP2D6-humanized transgenic mice can be translated to humans. This proof of concept study provides evidence for CYP2D6 regulation by an inducer of SHP expression, namely, the FXR agonist GW4064.
Pan, Xian; Lee, Yoon-Kwang
2015-01-01
Cytochrome P450 2D6 (CYP2D6) is a major drug-metabolizing enzyme responsible for eliminating approximately 20% of marketed drugs. Studies have shown that differential transcriptional regulation of CYP2D6 may contribute to large interindividual variability in CYP2D6-mediated drug metabolism. However, the factors governing CYP2D6 transcription are largely unknown. We previously demonstrated small heterodimer partner (SHP) as a novel transcriptional repressor of CYP2D6 expression. SHP is a representative target gene of the farnesoid X receptor (FXR). The objective of this study is to investigate whether an agonist of FXR, 3-(2,6-dichlorophenyl)-4-(3′-carboxy-2-chlorostilben-4-yl)oxymethyl-5-isopropylisoxazole (GW4064), alters CYP2D6 expression and activity. In CYP2D6-humanized transgenic mice, GW4064 decreased hepatic CYP2D6 expression and activity (by 2-fold) while increasing SHP expression (by 2-fold) and SHP recruitment to the CYP2D6 promoter. CYP2D6 repression by GW4064 was abrogated in Shp(−/−);CYP2D6 mice, indicating a critical role of SHP in CYP2D6 regulation by GW4064. Also, GW4064 decreased CYP2D6 expression (by 2-fold) in primary human hepatocytes, suggesting that the results obtained in CYP2D6-humanized transgenic mice can be translated to humans. This proof of concept study provides evidence for CYP2D6 regulation by an inducer of SHP expression, namely, the FXR agonist GW4064. PMID:25926433
Simulation of subgrid orographic precipitation with an embedded 2-D cloud-resolving model
NASA Astrophysics Data System (ADS)
Jung, Joon-Hee; Arakawa, Akio
2016-03-01
By explicitly resolving cloud-scale processes with embedded two-dimensional (2-D) cloud-resolving models (CRMs), superparameterized global atmospheric models have successfully simulated various atmospheric events over a wide range of time scales. Up to now, however, such models have not included the effects of topography on the CRM grid scale. We have used both 3-D and 2-D CRMs to simulate the effects of topography with prescribed "large-scale" winds. The 3-D CRM is used as a benchmark. The results show that the mean precipitation can be simulated reasonably well by using a 2-D representation of topography as long as the statistics of the topography such as the mean and standard deviation are closely represented. It is also shown that the use of a set of two perpendicular 2-D grids can significantly reduce the error due to a 2-D representation of topography.
Protein kinase A represses skeletal myogenesis by targeting myocyte enhancer factor 2D.
Du, Min; Perry, Robert L S; Nowacki, Nathaniel B; Gordon, Joseph W; Salma, Jahan; Zhao, Jianzhong; Aziz, Arif; Chan, Joseph; Siu, K W Michael; McDermott, John C
2008-05-01
Activation of protein kinase A (PKA) by elevation of the intracellular cyclic AMP (cAMP) level inhibits skeletal myogenesis. Previously, an indirect modulation of the myogenic regulatory factors (MRFs) was implicated as the mechanism. Because myocyte enhancer factor 2 (MEF2) proteins are key regulators of myogenesis and obligatory partners for the MRFs, here we assessed whether these proteins could be involved in PKA-mediated myogenic repression. Initially, in silico analysis revealed several consensus PKA phosphoacceptor sites on MEF2, and subsequent analysis by in vitro kinase assays indicated that PKA directly and efficiently phosphorylates MEF2D. Using mass spectrometric determination of phosphorylated residues, we document that MEF2D serine 121 and serine 190 are targeted by PKA. Transcriptional reporter gene assays to assess MEF2D function revealed that PKA potently represses the transactivation properties of MEF2D. Furthermore, engineered mutation of MEF2D PKA phosphoacceptor sites (serines 121 and 190 to alanine) rendered a PKA-resistant MEF2D protein, which efficiently rescues myogenesis from PKA-mediated repression. Concomitantly, increased intracellular cAMP-mediated PKA activation also resulted in an enhanced nuclear accumulation of histone deacetylase 4 (HDAC4) and a subsequent increase in the MEF2D-HDAC4 repressor complex. Collectively, these data identify MEF2D as a primary target of PKA signaling in myoblasts that leads to inhibition of the skeletal muscle differentiation program.
Impact of CYP2D6 polymorphisms on clinical efficacy and tolerability of metoprolol tartrate.
Hamadeh, I S; Langaee, T Y; Dwivedi, R; Garcia, S; Burkley, B M; Skaar, T C; Chapman, A B; Gums, J G; Turner, S T; Gong, Y; Cooper-DeHoff, R M; Johnson, J A
2014-08-01
Metoprolol is a selective β-1 adrenergic receptor blocker that undergoes extensive metabolism by the polymorphic enzyme cytochrome P450 2D6 (CYP2D6). Our objective was to investigate the influence of CYP2D6 polymorphisms on the efficacy and tolerability of metoprolol tartrate. Two hundred and eighty-one participants with uncomplicated hypertension received 50 mg of metoprolol twice daily followed by response-guided titration to 100 mg twice daily. Phenotypes were assigned based on results of CYP2D6 genotyping and copy number variation assays. Clinical response to metoprolol and adverse effect rates were analyzed in relation to CYP2D6 phenotypes using appropriate statistical tests. Heart rate response differed significantly by CYP2D6 phenotype (P < 0.0001), with poor and intermediate metabolizers showing greater reduction. However, blood pressure response and adverse effect rates were not significantly different by CYP2D6 phenotype. Other than a significant difference in heart rate response, CYP2D6 polymorphisms were not determinants of variability in metoprolol response or tolerability.
Influence of Elevation Data Source on 2D Hydraulic Modelling
NASA Astrophysics Data System (ADS)
Bakuła, Krzysztof; Stępnik, Mateusz; Kurczyński, Zdzisław
2016-08-01
The aim of this paper is to analyse the influence of the source of various elevation data on hydraulic modelling in open channels. In the research, digital terrain models from different datasets were evaluated and used in two-dimensional hydraulic models. The following aerial and satellite elevation data were used to create the representation of terrain - digital terrain model: airborne laser scanning, image matching, elevation data collected in the LPIS, EuroDEM, and ASTER GDEM. From the results of five 2D hydrodynamic models with different input elevation data, the maximum depth and flow velocity of water were derived and compared with the results of the most accurate ALS data. For such an analysis a statistical evaluation and differences between hydraulic modelling results were prepared. The presented research proved the importance of the quality of elevation data in hydraulic modelling and showed that only ALS and photogrammetric data can be the most reliable elevation data source in accurate 2D hydraulic modelling.
CYP2D7 Sequence Variation Interferes with TaqMan CYP2D6*15 and *35 Genotyping
Riffel, Amanda K.; Dehghani, Mehdi; Hartshorne, Toinette; Floyd, Kristen C.; Leeder, J. Steven; Rosenblatt, Kevin P.; Gaedigk, Andrea
2016-01-01
TaqMan™ genotyping assays are widely used to genotype CYP2D6, which encodes a major drug metabolizing enzyme. Assay design for CYP2D6 can be challenging owing to the presence of two pseudogenes, CYP2D7 and CYP2D8, structural and copy number variation and numerous single nucleotide polymorphisms (SNPs) some of which reflect the wild-type sequence of the CYP2D7 pseudogene. The aim of this study was to identify the mechanism causing false-positive CYP2D6*15 calls and remediate those by redesigning and validating alternative TaqMan genotype assays. Among 13,866 DNA samples genotyped by the CompanionDx® lab on the OpenArray platform, 70 samples were identified as heterozygotes for 137Tins, the key SNP of CYP2D6*15. However, only 15 samples were confirmed when tested with the Luminex xTAG CYP2D6 Kit and sequencing of CYP2D6-specific long range (XL)-PCR products. Genotype and gene resequencing of CYP2D6 and CYP2D7-specific XL-PCR products revealed a CC>GT dinucleotide SNP in exon 1 of CYP2D7 that reverts the sequence to CYP2D6 and allows a TaqMan assay PCR primer to bind. Because CYP2D7 also carries a Tins, a false-positive mutation signal is generated. This CYP2D7 SNP was also responsible for generating false-positive signals for rs769258 (CYP2D6*35) which is also located in exon 1. Although alternative CYP2D6*15 and *35 assays resolved the issue, we discovered a novel CYP2D6*15 subvariant in one sample that carries additional SNPs preventing detection with the alternate assay. The frequency of CYP2D6*15 was 0.1% in this ethnically diverse U.S. population sample. In addition, we also discovered linkage between the CYP2D7 CC>GT dinucleotide SNP and the 77G>A (rs28371696) SNP of CYP2D6*43. The frequency of this tentatively functional allele was 0.2%. Taken together, these findings emphasize that regardless of how careful genotyping assays are designed and evaluated before being commercially marketed, rare or unknown SNPs underneath primer and/or probe regions can impact
CYP2D7 Sequence Variation Interferes with TaqMan CYP2D6 (*) 15 and (*) 35 Genotyping.
Riffel, Amanda K; Dehghani, Mehdi; Hartshorne, Toinette; Floyd, Kristen C; Leeder, J Steven; Rosenblatt, Kevin P; Gaedigk, Andrea
2015-01-01
TaqMan™ genotyping assays are widely used to genotype CYP2D6, which encodes a major drug metabolizing enzyme. Assay design for CYP2D6 can be challenging owing to the presence of two pseudogenes, CYP2D7 and CYP2D8, structural and copy number variation and numerous single nucleotide polymorphisms (SNPs) some of which reflect the wild-type sequence of the CYP2D7 pseudogene. The aim of this study was to identify the mechanism causing false-positive CYP2D6 (*) 15 calls and remediate those by redesigning and validating alternative TaqMan genotype assays. Among 13,866 DNA samples genotyped by the CompanionDx® lab on the OpenArray platform, 70 samples were identified as heterozygotes for 137Tins, the key SNP of CYP2D6 (*) 15. However, only 15 samples were confirmed when tested with the Luminex xTAG CYP2D6 Kit and sequencing of CYP2D6-specific long range (XL)-PCR products. Genotype and gene resequencing of CYP2D6 and CYP2D7-specific XL-PCR products revealed a CC>GT dinucleotide SNP in exon 1 of CYP2D7 that reverts the sequence to CYP2D6 and allows a TaqMan assay PCR primer to bind. Because CYP2D7 also carries a Tins, a false-positive mutation signal is generated. This CYP2D7 SNP was also responsible for generating false-positive signals for rs769258 (CYP2D6 (*) 35) which is also located in exon 1. Although alternative CYP2D6 (*) 15 and (*) 35 assays resolved the issue, we discovered a novel CYP2D6 (*) 15 subvariant in one sample that carries additional SNPs preventing detection with the alternate assay. The frequency of CYP2D6 (*) 15 was 0.1% in this ethnically diverse U.S. population sample. In addition, we also discovered linkage between the CYP2D7 CC>GT dinucleotide SNP and the 77G>A (rs28371696) SNP of CYP2D6 (*) 43. The frequency of this tentatively functional allele was 0.2%. Taken together, these findings emphasize that regardless of how careful genotyping assays are designed and evaluated before being commercially marketed, rare or unknown SNPs underneath primer
Testing earthquake source inversion methodologies
Page, M.; Mai, P.M.; Schorlemmer, D.
2011-01-01
Source Inversion Validation Workshop; Palm Springs, California, 11-12 September 2010; Nowadays earthquake source inversions are routinely performed after large earthquakes and represent a key connection between recorded seismic and geodetic data and the complex rupture process at depth. The resulting earthquake source models quantify the spatiotemporal evolution of ruptures. They are also used to provide a rapid assessment of the severity of an earthquake and to estimate losses. However, because of uncertainties in the data, assumed fault geometry and velocity structure, and chosen rupture parameterization, it is not clear which features of these source models are robust. Improved understanding of the uncertainty and reliability of earthquake source inversions will allow the scientific community to use the robust features of kinematic inversions to more thoroughly investigate the complexity of the rupture process and to better constrain other earthquakerelated computations, such as ground motion simulations and static stress change calculations.
CFD code comparison for 2D airfoil flows
NASA Astrophysics Data System (ADS)
Sørensen, Niels N.; Méndez, B.; Muñoz, A.; Sieros, G.; Jost, E.; Lutz, T.; Papadakis, G.; Voutsinas, S.; Barakos, G. N.; Colonia, S.; Baldacchino, D.; Baptista, C.; Ferreira, C.
2016-09-01
The current paper presents the effort, in the EU AVATAR project, to establish the necessary requirements to obtain consistent lift over drag ratios among seven CFD codes. The flow around a 2D airfoil case is studied, for both transitional and fully turbulent conditions at Reynolds numbers of 3 × 106 and 15 × 106. The necessary grid resolution, domain size, and iterative convergence criteria to have consistent results are discussed, and suggestions are given for best practice. For the fully turbulent results four out of seven codes provide consistent results. For the laminar-turbulent transitional results only three out of seven provided results, and the agreement is generally lower than for the fully turbulent case.
GEO2D - Two-Dimensional Computer Model of a Ground Source Heat Pump System
James Menart
2013-06-07
This file contains a zipped file that contains many files required to run GEO2D. GEO2D is a computer code for simulating ground source heat pump (GSHP) systems in two-dimensions. GEO2D performs a detailed finite difference simulation of the heat transfer occurring within the working fluid, the tube wall, the grout, and the ground. Both horizontal and vertical wells can be simulated with this program, but it should be noted that the vertical wall is modeled as a single tube. This program also models the heat pump in conjunction with the heat transfer occurring. GEO2D simulates the heat pump and ground loop as a system. Many results are produced by GEO2D as a function of time and position, such as heat transfer rates, temperatures and heat pump performance. On top of this information from an economic comparison between the geothermal system simulated and a comparable air heat pump systems or a comparable gas, oil or propane heating systems with a vapor compression air conditioner. The version of GEO2D in the attached file has been coupled to the DOE heating and cooling load software called ENERGYPLUS. This is a great convenience for the user because heating and cooling loads are an input to GEO2D. GEO2D is a user friendly program that uses a graphical user interface for inputs and outputs. These make entering data simple and they produce many plotted results that are easy to understand. In order to run GEO2D access to MATLAB is required. If this program is not available on your computer you can download the program MCRInstaller.exe, the 64 bit version, from the MATLAB website or from this geothermal depository. This is a free download which will enable you to run GEO2D..
On the Inverse Problem of Binocular 3D Motion Perception
Lages, Martin; Heron, Suzanne
2010-01-01
It is shown that existing processing schemes of 3D motion perception such as interocular velocity difference, changing disparity over time, as well as joint encoding of motion and disparity, do not offer a general solution to the inverse optics problem of local binocular 3D motion. Instead we suggest that local velocity constraints in combination with binocular disparity and other depth cues provide a more flexible framework for the solution of the inverse problem. In the context of the aperture problem we derive predictions from two plausible default strategies: (1) the vector normal prefers slow motion in 3D whereas (2) the cyclopean average is based on slow motion in 2D. Predicting perceived motion directions for ambiguous line motion provides an opportunity to distinguish between these strategies of 3D motion processing. Our theoretical results suggest that velocity constraints and disparity from feature tracking are needed to solve the inverse problem of 3D motion perception. It seems plausible that motion and disparity input is processed in parallel and integrated late in the visual processing hierarchy. PMID:21124957
Source Inversion Validation: Quantifying Uncertainties in Earthquake Source Inversions
NASA Astrophysics Data System (ADS)
Mai, P. M.; Page, M. T.; Schorlemmer, D.
2010-12-01
Earthquake source inversions image the spatio-temporal rupture evolution on one or more fault planes using seismic and/or geodetic data. Source inversion methods thus represent an important research tool in seismology to unravel the complexity of earthquake ruptures. Subsequently, source-inversion results are used to study earthquake mechanics, to develop spontaneous dynamic rupture models, to build models for generating rupture realizations for ground-motion simulations, and to perform Coulomb-stress modeling. In all these applications, the underlying finite-source rupture models are treated as “data” (input information), but the uncertainties in these data (i.e. source models obtained from solving an inherently ill-posed inverse problem) are hardly known, and almost always neglected. The Source Inversion Validation (SIV) project attempts to better understand the intra-event variability of earthquake rupture models. We plan to build a long-standing and rigorous testing platform to examine the current state-of-the-art in earthquake source inversion that also facilitates to develop robust approaches to quantify rupture-model uncertainties. Our contribution reviews the current status of the SIV project, recent forward-modeling tests for point and extended sources in layered media, and discusses the strategy of the SIV-project for the coming years.
2D Seismic Reflection Data across Central Illinois
Smith, Valerie; Leetaru, Hannes
2014-09-30
In a continuing collaboration with the Midwest Geologic Sequestration Consortium (MGSC) on the Evaluation of the Carbon Sequestration Potential of the Cambro-Ordovician Strata of the Illinois and Michigan Basins project, Schlumberger Carbon Services and WesternGeco acquired two-dimensional (2D) seismic data in the Illinois Basin. This work included the design, acquisition and processing of approximately 125 miles of (2D) seismic reflection surveys running west to east in the central Illinois Basin. Schlumberger Carbon Services and WesternGeco oversaw the management of the field operations (including a pre-shoot planning, mobilization, acquisition and de-mobilization of the field personnel and equipment), procurement of the necessary permits to conduct the survey, post-shoot closure, processing of the raw data, and provided expert consultation as needed in the interpretation of the delivered product. Three 2D seismic lines were acquired across central Illinois during November and December 2010 and January 2011. Traversing the Illinois Basin, this 2D seismic survey was designed to image the stratigraphy of the Cambro-Ordovician sections and also to discern the basement topography. Prior to this survey, there were no regionally extensive 2D seismic data spanning this section of the Illinois Basin. Between the NW side of Morgan County and northwestern border of Douglas County, these seismic lines ran through very rural portions of the state. Starting in Morgan County, Line 101 was the longest at 93 miles in length and ended NE of Decatur, Illinois. Line 501 ran W-E from the Illinois Basin – Decatur Project (IBDP) site to northwestern Douglas County and was 25 miles in length. Line 601 was the shortest and ran N-S past the IBDP site and connected lines 101 and 501. All three lines are correlated to well logs at the IBDP site. Originally processed in 2011, the 2D seismic profiles exhibited a degradation of signal quality below ~400 millisecond (ms) which made
Facial biometrics based on 2D vector geometry
NASA Astrophysics Data System (ADS)
Malek, Obaidul; Venetsanopoulos, Anastasios; Androutsos, Dimitrios
2014-05-01
The main challenge of facial biometrics is its robustness and ability to adapt to changes in position orientation, facial expression, and illumination effects. This research addresses the predominant deficiencies in this regard and systematically investigates a facial authentication system in the Euclidean domain. In the proposed method, Euclidean geometry in 2D vector space is being constructed for features extraction and the authentication method. In particular, each assigned point of the candidates' biometric features is considered to be a 2D geometrical coordinate in the Euclidean vector space. Algebraic shapes of the extracted candidate features are also computed and compared. The proposed authentication method is being tested on images from the public "Put Face Database". The performance of the proposed method is evaluated based on Correct Recognition (CRR), False Acceptance (FAR), and False Rejection (FRR) rates. The theoretical foundation of the proposed method along with the experimental results are also presented in this paper. The experimental results demonstrate the effectiveness of the proposed method.
3D surface configuration modulates 2D symmetry detection.
Chen, Chien-Chung; Sio, Lok-Teng
2015-02-01
We investigated whether three-dimensional (3D) information in a scene can affect symmetry detection. The stimuli were random dot patterns with 15% dot density. We measured the coherence threshold, or the proportion of dots that were the mirror reflection of the other dots in the other half of the image about a central vertical axis, at 75% accuracy with a 2AFC paradigm under various 3D configurations produced by the disparity between the left and right eye images. The results showed that symmetry detection was difficult when the corresponding dots across the symmetry axis were on different frontoparallel or inclined planes. However, this effect was not due to a difference in distance, as the observers could detect symmetry on a slanted surface, where the depth of the two sides of the symmetric axis was different. The threshold was reduced for a hinge configuration where the join of two slanted surfaces coincided with the axis of symmetry. Our result suggests that the detection of two-dimensional (2D) symmetry patterns is subject to the 3D configuration of the scene; and that coplanarity across the symmetry axis and consistency between the 2D pattern and 3D structure are important factors for symmetry detection.
2D Quantum Transport Modeling in Nanoscale MOSFETs
NASA Technical Reports Server (NTRS)
Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, B.
2001-01-01
We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions, oxide tunneling and phase-breaking scattering are treated on an equal footing. Electron bandstructure is treated within the anisotropic effective mass approximation. We present the results of our simulations of MIT 25 and 90 nm "well-tempered" MOSFETs and compare them to those of classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. These results are consistent with 1D Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and subthreshold current has been studied. The shorter gate length device has an order of magnitude smaller leakage current than the longer gate length device without a significant trade-off in on-current.
NASA Astrophysics Data System (ADS)
Cowie, Leanne; Kusznir, Nick
2014-05-01
Subsidence analysis of sedimentary basins and rifted continental margins requires a correction for the anomalous uplift or subsidence arising from mantle dynamic topography. Whilst different global model predictions of mantle dynamic topography may give a broadly similar pattern at long wavelengths, they differ substantially in the predicted amplitude and at shorter wavelengths. As a consequence the accuracy of predicted mantle dynamic topography is not sufficiently good to provide corrections for subsidence analysis. Measurements of present day anomalous subsidence, which we attribute to mantle dynamic topography, have been made for three rifted continental margins; offshore Iberia, the Gulf of Aden and southern Angola. We determine residual depth anomaly (RDA), corrected for sediment loading and crustal thickness variation for 2D profiles running from unequivocal oceanic crust across the continental ocean boundary onto thinned continental crust. Residual depth anomalies (RDA), corrected for sediment loading using flexural backstripping and decompaction, have been calculated by comparing observed and age predicted oceanic bathymetries at these margins. Age predicted bathymetric anomalies have been calculated using the thermal plate model predictions from Crosby & McKenzie (2009). Non-zero sediment corrected RDAs may result from anomalous oceanic crustal thickness with respect to the global average or from anomalous uplift or subsidence. Gravity anomaly inversion incorporating a lithosphere thermal gravity anomaly correction and sediment thickness from 2D seismic reflection data has been used to determine Moho depth, calibrated using seismic refraction, and oceanic crustal basement thickness. Crustal basement thicknesses derived from gravity inversion together with Airy isostasy have been used to correct for variations of crustal thickness from a standard oceanic thickness of 7km. The 2D profiles of RDA corrected for both sediment loading and non-standard crustal
2 D patterns of soil gas diffusivity , soil respiration, and methane oxidation in a soil profile
NASA Astrophysics Data System (ADS)
Maier, Martin; Schack-Kirchner, Helmer; Lang, Friederike
2015-04-01
The apparent gas diffusion coefficient in soil (DS) is an important parameter describing soil aeration, which makes it a key parameter for root growth and gas production and consumption. Horizontal homogeneity in soil profiles is assumed in most studies for soil properties - including DS. This assumption, however, is not valid, even in apparently homogeneous soils, as we know from studies using destructive sampling methods. Using destructive methods may allow catching a glimpse, but a large uncertainty remains, since locations between the sampling positions cannot be analyzed, and measurements cannot be repeated. We developed a new method to determine in situ the apparent soil gas diffusion coefficient in order to examine 2 D pattern of DS and methane oxidation in a soil profile. Different tracer gases (SF6, CF4, C2H6) were injected continuously into the subsoil and measured at several locations in the soil profile. These data allow for modelling inversely the 2 D patterns of DS using Finite Element Modeling. The 2D DS patterns were then combined with naturally occurring CH4 and CO2 concentrations sampled at the same locations to derive the 2D pattern of soil respiration and methane oxidation in the soil profile. We show that methane oxidation and soil respiration zones shift within the soil profile while the gas fluxes at the surface remain rather stable during a the 3 week campaign.
The Sobolev Stability Threshold for 2D Shear Flows Near Couette
NASA Astrophysics Data System (ADS)
Bedrossian, Jacob; Vicol, Vlad; Wang, Fei
2016-08-01
We consider the 2D Navier-Stokes equation on T × R , with initial datum that is ɛ -close in H^N to a shear flow (U(y), 0), where Vert U(y) - yVert _{H^{N+4}} ≪ 1 and N>1 . We prove that if ɛ ≪ ν ^{1/2} , where ν denotes the inverse Reynolds number, then the solution of the Navier-Stokes equation remains ɛ -close in H^1 to (e^{t ν partial _{yy}}U(y),0) for all t>0 . Moreover, the solution converges to a decaying shear flow for times t ≫ ν ^{-1/3} by a mixing-enhanced dissipation effect, and experiences a transient growth of gradients. In particular, this shows that the stability threshold in finite regularity scales no worse than ν ^{1/2} for 2D shear flows close to the Couette flow.
Inverse anticipating chaos synchronization.
Shahverdiev, E M; Sivaprakasam, S; Shore, K A
2002-07-01
We derive conditions for achieving inverse anticipating synchronization where a driven time-delay chaotic system synchronizes to the inverse future state of the driver. The significance of inverse anticipating chaos in delineating synchronization regimes in time-delay systems is elucidated. The concept is extended to cascaded time-delay systems.
High resolution 3D nonlinear integrated inversion
NASA Astrophysics Data System (ADS)
Li, Yong; Wang, Xuben; Li, Zhirong; Li, Qiong; Li, Zhengwen
2009-06-01
The high resolution 3D nonlinear integrated inversion method is based on nonlinear theory. Under layer control, the log data from several wells (or all wells) in the study area and seismic trace data adjacent to the wells are input to a network with multiple inputs and outputs and are integratedly trained to obtain an adaptive weight function of the entire study area. Integrated nonlinear mapping relationships are built and updated by the lateral and vertical geologic variations of the reservoirs. Therefore, the inversion process and its inversion results can be constrained and controlled and a stable seismic inversion section with high resolution with velocity inversion, impedance inversion, and density inversion sections, can be gained. Good geologic effects have been obtained in model computation tests and real data processing, which verified that this method has high precision, good practicality, and can be used for quantitative reservoir analysis.
Canonical vs. micro-canonical sampling methods in a 2D Ising model
Kepner, J.
1990-12-01
Canonical and micro-canonical Monte Carlo algorithms were implemented on a 2D Ising model. Expressions for the internal energy, U, inverse temperature, Z, and specific heat, C, are given. These quantities were calculated over a range of temperature, lattice sizes, and time steps. Both algorithms accurately simulate the Ising model. To obtain greater than three decimal accuracy from the micro-canonical method requires that the more complicated expression for Z be used. The overall difference between the algorithms is small. The physics of the problem under study should be the deciding factor in determining which algorithm to use. 13 refs., 6 figs., 2 tabs.
2D/3D image (facial) comparison using camera matching.
Goos, Mirelle I M; Alberink, Ivo B; Ruifrok, Arnout C C
2006-11-10
A problem in forensic facial comparison of images of perpetrators and suspects is that distances between fixed anatomical points in the face, which form a good starting point for objective, anthropometric comparison, vary strongly according to the position and orientation of the camera. In case of a cooperating suspect, a 3D image may be taken using e.g. a laser scanning device. By projecting the 3D image onto a 2D image with the suspect's head in the same pose as that of the perpetrator, using the same focal length and pixel aspect ratio, numerical comparison of (ratios of) distances between fixed points becomes feasible. An experiment was performed in which, starting from two 3D scans and one 2D image of two colleagues, male and female, and using seven fixed anatomical locations in the face, comparisons were made for the matching and non-matching case. Using this method, the non-matching pair cannot be distinguished from the matching pair of faces. Facial expression and resolution of images were all more or less optimal, and the results of the study are not encouraging for the use of anthropometric arguments in the identification process. More research needs to be done though on larger sets of facial comparisons. PMID:16337353
Mass loss in 2D rotating stellar models
Lovekin, Caterine; Deupree, Bob
2010-10-05
Radiatively driven mass loss is an important factor in the evolution of massive stars . The mass loss rates depend on a number of stellar parameters, including the effective temperature and luminosity. Massive stars are also often rapidly rotating, which affects their structure and evolution. In sufficiently rapidly rotating stars, both the effective temperature and radius vary significantly as a function of latitude, and hence mass loss rates can vary appreciably between the poles and the equator. In this work, we discuss the addition of mass loss to a 2D stellar evolution code (ROTORC) and compare evolution sequences with and without mass loss. Preliminary results indicate that a full 2D calculation of mass loss using the local effective temperature and luminosity can significantly affect the distribution of mass loss in rotating main sequence stars. More mass is lost from the pole than predicted by 1D models, while less mass is lost at the equator. This change in the distribution of mass loss will affect the angular momentum loss, the surface temperature and luminosity, and even the interior structure of the star. After a single mass loss event, these effects are small, but can be expected to accumulate over the course of the main sequence evolution.
Modelling RF sources using 2-D PIC codes
Eppley, K.R.
1993-03-01
In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT`S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field (``port approximation``). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.
Modelling RF sources using 2-D PIC codes
Eppley, K.R.
1993-03-01
In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT'S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field ( port approximation''). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.
Controlling cell growth with tailorable 2D nanoholes arrays.
Fragal, Vanessa H; Cellet, Thelma Sley P; Fragal, Elizângela H; Pereira, Guilherme M; Garcia, Francielle P; Nakamura, Celso V; Asefa, Tewodros; Rubira, Adley F; Silva, Rafael
2016-03-15
A facile and reproducible route that can lead to two-dimensional arrays of nanopores in thin polymer films is demonstrated. The formation of the pores in the polymer films involves breath figure phenomenon and occurs during the film deposition by spin coating. The formation of nanoporous thin films takes only few seconds, and the method does not require complex equipment or expensive chemicals. This method also constitutes a straightforward approach to control the size of the pores formed in thin films. Besides allowing control over the average pore size of the porous films, the use of dynamic deposition with the breath figure phenomenon causes the reduction in the pore size to nanometer scale. The nanoporous arrays obtained by the breath figure are applied as substrates for cell growth, and the effect of their nanopore size on cell growth was evaluated. Notably, it is found that cell viability is related to pore size, where 2D nanoporous structure is more beneficial for cell culture than 2D microporous structures. The change in the average pore size of the polymer films from 1.22 μm to 346 nm results in a threefold increase in cell viability. PMID:26722796
Conformal Laplace superintegrable systems in 2D: polynomial invariant subspaces
NASA Astrophysics Data System (ADS)
Escobar-Ruiz, M. A.; Miller, Willard, Jr.
2016-07-01
2nd-order conformal superintegrable systems in n dimensions are Laplace equations on a manifold with an added scalar potential and 2n-1 independent 2nd order conformal symmetry operators. They encode all the information about Helmholtz (eigenvalue) superintegrable systems in an efficient manner: there is a 1-1 correspondence between Laplace superintegrable systems and Stäckel equivalence classes of Helmholtz superintegrable systems. In this paper we focus on superintegrable systems in two-dimensions, n = 2, where there are 44 Helmholtz systems, corresponding to 12 Laplace systems. For each Laplace equation we determine the possible two-variate polynomial subspaces that are invariant under the action of the Laplace operator, thus leading to families of polynomial eigenfunctions. We also study the behavior of the polynomial invariant subspaces under a Stäckel transform. The principal new results are the details of the polynomial variables and the conditions on parameters of the potential corresponding to polynomial solutions. The hidden gl 3-algebraic structure is exhibited for the exact and quasi-exact systems. For physically meaningful solutions, the orthogonality properties and normalizability of the polynomials are presented as well. Finally, for all Helmholtz superintegrable solvable systems we give a unified construction of one-dimensional (1D) and two-dimensional (2D) quasi-exactly solvable potentials possessing polynomial solutions, and a construction of new 2D PT-symmetric potentials is established.
Asymmetric 2D spatial beam filtering by photonic crystals
NASA Astrophysics Data System (ADS)
Gailevicius, D.; Purlys, V.; Maigyte, L.; Gaizauskas, E.; Peckus, M.; Gadonas, R.; Staliunas, K.
2016-04-01
Spatial filtering techniques are important for improving the spatial quality of light beams. Photonic crystals (PhCs) with a selective spatial (angular) transmittance can also provide spatial filtering with the added benefit transversal symmetries, submillimeter dimensions and monolithic integration in other devices, such as micro-lasers or semiconductor lasers. Workable bandgap PhC configurations require a modulated refractive index with period lengths that are approximately less than the wavelength of radiation. This imposes technical limitations, whereby the available direct laser write (DLW) fabrication techniques are limited in resolution and refractive index depth. If, however, a deflection mechanism is chosen instead, a functional filter PhC can be produced that is operational in the visible wavelength regime. For deflection based PhCs glass is an attractive choice as it is highly stable medium. 2D and 3D PhC filter variations have already been produced on soda-lime glass. However, little is known about how to control the scattering of PhCs when approaching the smallest period values. Here we look into the internal structure of the initially symmetric geometry 2D PhCs and associating it with the resulting transmittance spectra. By varying the DLW fabrication beam parameters and scanning algorithms, we show that such PhCs contain layers that are comprised of semi-tilted structure voxels. We show the appearance of asymmetry can be compensated in order to circumvent some negative effects at the cost of potentially maximum scattering efficiency.
Using dispersive medium to control excitons in 2D materials
NASA Astrophysics Data System (ADS)
Klots, Andrey; Bolotin, Kirill I.
Excitons in 2D materials (2DMs) are known to be sensitive to the surrounding environment. This makes it possible to modify 2D excitons by depositing materials with controlled dielectric constant on top of 2DMs. This possibility becomes especially interesting if we consider materials with dielectric permittivity ɛ that depends both on wavevector k (this happens if the medium is spatially non-uniform) and frequency ω. Here, we develop platforms to control ɛ (k , ω) and explore resulting changes in light-matter interactions of 2DMs. To examine the effect of wavevector-dependent permittivity of the medium, we study absorption/photoluminescence of graphene and MoS2 in the vicinity of highly non-uniform medium - an array of metal nanoparticles, 3-5 nm in diameter. In this case absorption of light can lead to creation of excitons with non-zero momentum. These dark states are not accessible via regular absorption spectroscopy. We study the case of frequency-dependent permittivity by surrounding MoS2 by a highly-dispersive media (e.g. dielectric liquids, graphene and VO2) . We demonstrate non-trivial frequency-dependent renormalization of the quasiparticle bandgap and exciton binding energies.
Charoenchokthavee, Wanaporn; Panomvana, Duangchit; Sriuranpong, Virote; Areepium, Nutthada
2016-01-01
Background Tamoxifen (TAM) is used in breast cancer treatment, but interindividual variabilities in TAM-metabolizing enzymes exist and have been linked to single nucleotide polymorphisms in the respective encoding genes. The different alleles and genotypes of these genes have been presented for Caucasians and Asians. This study aimed to explore the prevalence of the incomplete functional alleles and genotypes of the CYP2D6 and CYP3A5 genes in Thai breast cancer patients undergoing TAM treatment. Patients and methods In total, 134 Thai breast cancer patients were randomly invited to join the Thai Tamoxifen Project. Their blood samples were collected and extracted for individual DNA. The alleles and genotypes were determined by real-time polymerase chain reaction with TaqMan® Drug Metabolism Genotyping Assays. Results The patients were aged from 27.0 years to 82.0 years with a body mass index range from 15.4 to 40.0, with the majority (103/134) in the early stage (stages 0–II) of breast cancer. The median duration of TAM administration was 17.2 months (interquartile range 16.1 months). Most (53%) of the patients were premenopausal with an estrogen receptor (ER) and progesterone receptor (PR) status of ER+/PR+ (71.7%), ER+/PR− (26.9%), ER−/PR+ (0.7%), and ER−/PR− (0.7%). The allele frequencies of CYP2D6*1, CYP2D6*2, CYP2D6*4, CYP2D6*10, CYP3A5*1, and CYP3A5*3 were 72.9%, 3.2%, 1.1%, 22.8%, 37.3%, and 62.7%, respectively, while the genotype frequencies of CYP2D6*1/*1, CYP2D6*1/*2, CYP2D6*2/*2, CYP2D6*4/*4, CYP2D6*1/*10, CYP2D6*2/*10, CYP2D6*4/*10, CYP2D6*10/*10, CYP3A5*1/*1, CYP3A5*1/*3, and CYP3A5*3/*3 were 9.7%, 2.2%, 3.7%, 1.5%, 15.7%, 9.7%, 3.7%, 53.7%, 13.4%, 47.8%, and 38.8%, respectively. Conclusion The majority (97.8%) of Thai breast cancer patients undergoing TAM treatment carry at least one incomplete functional allele, including 20.9% of the patients who carry only incomplete functional alleles for both the CYP2D6 and CYP3A5 genes. This research
NASA Technical Reports Server (NTRS)
Kapoor, Kamlesh; Anderson, Bernhard H.; Shaw, Robert J.
1994-01-01
A two-dimensional computational code, PRLUS2D, which was developed for the reactive propulsive flows of ramjets and scramjets, was validated for two-dimensional shock-wave/turbulent-boundary-layer interactions. The problem of compression corners at supersonic speeds was solved using the RPLUS2D code. To validate the RPLUS2D code for hypersonic speeds, it was applied to a realistic hypersonic inlet geometry. Both the Baldwin-Lomax and the Chien two-equation turbulence models were used. Computational results showed that the RPLUS2D code compared very well with experimentally obtained data for supersonic compression corner flows, except in the case of large separated flows resulting from the interactions between the shock wave and turbulent boundary layer. The computational results compared well with the experiment results in a hypersonic NASA P8 inlet case, with the Chien two-equation turbulence model performing better than the Baldwin-Lomax model.
Computational Screening of 2D Materials for Photocatalysis.
Singh, Arunima K; Mathew, Kiran; Zhuang, Houlong L; Hennig, Richard G
2015-03-19
Two-dimensional (2D) materials exhibit a range of extraordinary electronic, optical, and mechanical properties different from their bulk counterparts with potential applications for 2D materials emerging in energy storage and conversion technologies. In this Perspective, we summarize the recent developments in the field of solar water splitting using 2D materials and review a computational screening approach to rapidly and efficiently discover more 2D materials that possess properties suitable for solar water splitting. Computational tools based on density-functional theory can predict the intrinsic properties of potential photocatalyst such as their electronic properties, optical absorbance, and solubility in aqueous solutions. Computational tools enable the exploration of possible routes to enhance the photocatalytic activity of 2D materials by use of mechanical strain, bias potential, doping, and pH. We discuss future research directions and needed method developments for the computational design and optimization of 2D materials for photocatalysis.
Synthetic Covalent and Non-Covalent 2D Materials.
Boott, Charlotte E; Nazemi, Ali; Manners, Ian
2015-11-16
The creation of synthetic 2D materials represents an attractive challenge that is ultimately driven by their prospective uses in, for example, electronics, biomedicine, catalysis, sensing, and as membranes for separation and filtration. This Review illustrates some recent advances in this diverse field with a focus on covalent and non-covalent 2D polymers and frameworks, and self-assembled 2D materials derived from nanoparticles, homopolymers, and block copolymers.
First 2D-ACAR Measurements on Cu with the new Spectrometer at TUM
NASA Astrophysics Data System (ADS)
Weber, J. A.; Böni, P.; Ceeh, H.; Leitner, M.; Hugenschmidt, Ch
2013-06-01
The two-dimensional measurement of the angular correlation of the positron annihilation radiation (2D-ACAR) is a powerful tool to investigate the electronic structure of materials. Here we report on the first results obtained with the new 2D-ACAR spectrometer at the Technische Universitat München (TUM). To get experience in processing and interpreting 2D-ACAR data, first measurements were made on copper. The obtained data are treated with standard procedures and compared to theoretical calculations. It is shown that the measurements are in good agreement with the calculations and that the Fermi surface can be entirely reconstructed using three projections only.
Differentiation of normal and leukemic cells by 2D light scattering label-free static cytometry.
Xie, Linyan; Liu, Qiao; Shao, Changshun; Su, Xuantao
2016-09-19
Two-dimensional (2D) light scattering patterns of single microspheres, normal granulocytes and leukemic cells are obtained by label-free static cytometry. Statistical results of experimental 2D light scattering patterns obtained from standard microspheres with a mean diameter of 4.19 μm agree well with theoretical simulations. High accuracy rates (greater than 92%) for label-free differentiation of normal granulocytes and leukemic cells, both the acute and chronic leukemic cells, are achieved by analyzing the 2D light scattering patterns. Our label-free static cytometry is promising for leukemia screening in clinics. PMID:27661908
A Geometric Boolean Library for 2D Objects
2006-01-05
The 2D Boolean Library is a collection of C++ classes -- which primarily represent 2D geometric data and relationships, and routines -- which contain algorithms for 2D geometric Boolean operations and utility functions. Classes are provided for 2D points, lines, arcs, edgeuses, loops, surfaces and mask sets. Routines are provided that incorporate the Boolean operations Union(OR), XOR, Intersection and Difference. Various analytical geometry routines and routines for importing and exporting the data in various filemore » formats, are also provided in the library.« less
2D numerical modelling of meandering channel formation
NASA Astrophysics Data System (ADS)
XIAO, Y.; ZHOU, G.; YANG, F. S.
2016-03-01
A 2D depth-averaged model for hydrodynamic sediment transport and river morphological adjustment was established. The sediment transport submodel takes into account the influence of non-uniform sediment with bed surface armoring and considers the impact of secondary flow in the direction of bed-load transport and transverse slope of the river bed. The bank erosion submodel incorporates a simple simulation method for updating bank geometry during either degradational or aggradational bed evolution. Comparison of the results obtained by the extended model with experimental and field data, and numerical predictions validate that the proposed model can simulate grain sorting in river bends and duplicate the characteristics of meandering river and its development. The results illustrate that by using its control factors, the improved numerical model can be applied to simulate channel evolution under different scenarios and improve understanding of patterning processes.
VizieR Online Data Catalog: The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003)
NASA Astrophysics Data System (ADS)
Colless, M.; Dalton, G.; Maddox, S.; Sutherland, W.; Norberg, P.; Cole, S.; Bland-Hawthorn, J.; Bridges, T.; Cannon, R.; Collins, C.; Couch, W.; Cross, N.; Deeley, K.; de Propris, R.; Driver, S. P.; Efstathiou, G.; Ellis, R. S.; Frenk, C. S.; Glazebrook, K.; Jackson, C.; Lahav, O.; Lewis, I.; Lumsden, S.; Madgwick, D.; Peacock, J. A.; Peterson, B. A.; Price, I.; Seaborne, M.; Taylor, K.
2007-11-01
The 2dF Galaxy Redshift Survey (2dFGRS) is a major spectroscopic survey taking full advantage of the unique capabilities of the 2dF facility built by the Anglo-Australian Observatory. The 2dFGRS is integrated with the 2dF QSO survey (2QZ, Cat. VII/241). The 2dFGRS obtained spectra for 245591 objects, mainly galaxies, brighter than a nominal extinction-corrected magnitude limit of bJ=19.45. Reliable (quality>=3) redshifts were obtained for 221414 galaxies. The galaxies cover an area of approximately 1500 square degrees selected from the extended APM Galaxy Survey in three regions: a North Galactic Pole (NGP) strip, a South Galactic Pole (SGP) strip, and random fields scattered around the SGP strip. Redshifts are measured from spectra covering 3600-8000 Angstroms at a two-pixel resolution of 9.0 Angstrom and a median S/N of 13 per pixel. All redshift identifications are visually checked and assigned a quality parameter Q in the range 1-5; Q>=3 redshifts are 98.4% reliable and have an rms uncertainty of 85 km/s. The overall redshift completeness for Q>=3 redshifts is 91.8% but this varies with magnitude from 99% for the brightest galaxies to 90% for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at http://www.mso.anu.edu.au/2dFGRS/. (6 data files).
Tuan, P.C.; Ju, M.C.
2000-03-01
A novel adaptive and robust input estimation inverse methodology of estimating the time-varying unknown heat flux, named as the input, on the two active boundaries of a 2-D inverse heat conduction problem is presented. The algorithm includes using the Kalman filter to propose a regression model between the residual innovation and the two thermal unknown boundaries flux through given 2-D heat conduction state-space models and noisy measurement sequence. Based on this regression equation, a recursive least-square estimator (RLSE) weighted by the forgetting factor is proposed to on-line estimate these unknowns. The adaptive and robust weighting technique is essential since unknowns input are time-varied and have unpredictable changing status. In this article, the authors provide the bandwidth analysis together with bias and variance tests to construct an efficient and robust forgetting factor as the ratio between the standard deviation of measurement and observable bias innovation at each time step. Herein, the unknowns are robustly and adaptively estimated under the system involving measurement noise, process error, and unpredictable change status of time-varying unknowns. The capabilities of the proposed algorithm are demonstrated through the comparison with the conventional input estimation algorithm and validated by two benchmark performance tests in 2-D cases. Results show that the proposed algorithm not only exhibits superior robust capability but also enhances the estimation performance and highly facilitates practical implementation.
Device and methods for "gold standard" registration of clinical 3D and 2D cerebral angiograms
NASA Astrophysics Data System (ADS)
Madan, Hennadii; Likar, Boštjan; Pernuš, Franjo; Å piclin, Žiga
2015-03-01
Translation of any novel and existing 3D-2D image registration methods into clinical image-guidance systems is limited due to lack of their objective validation on clinical image datasets. The main reason is that, besides the calibration of the 2D imaging system, a reference or "gold standard" registration is very difficult to obtain on clinical image datasets. In the context of cerebral endovascular image-guided interventions (EIGIs), we present a calibration device in the form of a headband with integrated fiducial markers and, secondly, propose an automated pipeline comprising 3D and 2D image processing, analysis and annotation steps, the result of which is a retrospective calibration of the 2D imaging system and an optimal, i.e., "gold standard" registration of 3D and 2D images. The device and methods were used to create the "gold standard" on 15 datasets of 3D and 2D cerebral angiograms, whereas each dataset was acquired on a patient undergoing EIGI for either aneurysm coiling or embolization of arteriovenous malformation. The use of the device integrated seamlessly in the clinical workflow of EIGI. While the automated pipeline eliminated all manual input or interactive image processing, analysis or annotation. In this way, the time to obtain the "gold standard" was reduced from 30 to less than one minute and the "gold standard" of 3D-2D registration on all 15 datasets of cerebral angiograms was obtained with a sub-0.1 mm accuracy.
The IDOL–UBE2D complex mediates sterol-dependent degradation of the LDL receptor
Zhang, Li; Fairall, Louise; Goult, Benjamin T.; Calkin, Anna C.; Hong, Cynthia; Millard, Christopher J.; Tontonoz, Peter; Schwabe, John W.R.
2011-01-01
We previously identified the E3 ubiquitin ligase IDOL as a sterol-dependent regulator of the LDL receptor (LDLR). The molecular pathway underlying IDOL action, however, remains to be determined. Here we report the identification and biochemical and structural characterization of an E2–E3 ubiquitin ligase complex for LDLR degradation. We identified the UBE2D family (UBE2D1–4) as E2 partners for IDOL that support both autoubiquitination and IDOL-dependent ubiquitination of the LDLR in a cell-free system. NMR chemical shift mapping and a 2.1 Å crystal structure of the IDOL RING domain–UBE2D1 complex revealed key interactions between the dimeric IDOL protein and the E2 enzyme. Analysis of the IDOL–UBE2D1 interface also defined the stereochemical basis for the selectivity of IDOL for UBE2Ds over other E2 ligases. Structure-based mutations that inhibit IDOL dimerization or IDOL–UBE2D interaction block IDOL-dependent LDLR ubiquitination and degradation. Furthermore, expression of a dominant-negative UBE2D enzyme inhibits the ability of IDOL to degrade the LDLR in cells. These results identify the IDOL–UBE2D complex as an important determinant of LDLR activity, and provide insight into molecular mechanisms underlying the regulation of cholesterol uptake. PMID:21685362
Disruption of KMT2D perturbs germinal center B cell development and promotes lymphomagenesis.
Zhang, Jiyuan; Dominguez-Sola, David; Hussein, Shafinaz; Lee, Ji-Eun; Holmes, Antony B; Bansal, Mukesh; Vlasevska, Sofija; Mo, Tongwei; Tang, Hongyan; Basso, Katia; Ge, Kai; Dalla-Favera, Riccardo; Pasqualucci, Laura
2015-10-01
Mutations in the gene encoding the KMT2D (or MLL2) methyltransferase are highly recurrent and occur early during tumorigenesis in diffuse large B cell lymphoma (DLBCL) and follicular lymphoma (FL). However, the functional consequences of these mutations and their role in lymphomagenesis are unknown. Here we show that FL- and DLBCL-associated KMT2D mutations impair KMT2D enzymatic activity, leading to diminished global H3K4 methylation in germinal-center (GC) B cells and DLBCL cells. Conditional deletion of Kmt2d early during B cell development, but not after initiation of the GC reaction, results in an increase in GC B cells and enhances B cell proliferation in mice. Moreover, genetic ablation of Kmt2d in mice overexpressing Bcl2 increases the incidence of GC-derived lymphomas resembling human tumors. These findings suggest that KMT2D acts as a tumor suppressor gene whose early loss facilitates lymphomagenesis by remodeling the epigenetic landscape of the cancer precursor cells. Eradication of KMT2D-deficient cells may thus represent a rational therapeutic approach for targeting early tumorigenic events. PMID:26366712
Measurements of Schottky barrier heights formed from metals and 2D transition metal dichalcogedides
NASA Astrophysics Data System (ADS)
Kim, Changsik; Moon, Inyong; Nam, Seunggeol; Cho, Yeonchoo; Shin, Hyeon-Jin; Park, Seongjun; Yoo, Won Jong
Schottky barrier height (SBH) is an important parameter that needs to be considered for designing electronic devices. However, for two dimensional (2D) materials based devices, SBH control is limited by 2D structure induced quantum confinement and 2D surface induced Fermi level pinning. In this work, we explore differences in measuring SBH between 2D and 3D materials. Recently, low temperature I-V measurement has been reported to extract SBH based on thermionic emission equation for Schottky diode. However, 2D devices are not real Schottky diode in that both source and drain metal electrodes make Schottky contact. According to our experimental results, SBH extracted from linear slope of ln (I/T3/2) against 1/T show widely diverse values, dependent on applied voltage bias and tested temperature which affect carrier transport including tunneling or thermionic emission across the metal-2D material interface. In this work, we wish to demonstrate the method to determine SBH and Fermi level pinning which are attributed to 2D transition metal dichalcogedides, differently from conventional 3D materials. .
Klassifikation von Standardebenen in der 2D-Echokardiographie mittels 2D-3D-Bildregistrierung
NASA Astrophysics Data System (ADS)
Bergmeir, Christoph; Subramanian, Navneeth
Zum Zweck der Entwicklung eines Systems, das einen unerfahrenen Anwender von Ultraschall (US) zur Aufnahme relevanter anatomischer Strukturen leitet, untersuchen wir die Machbarkeit von 2D-US zu 3D-CT Registrierung. Wir verwenden US-Aufnahmen von Standardebenen des Herzens, welche zu einem 3D-CT-Modell registriert werden. Unser Algorithmus unterzieht sowohl die US-Bilder als auch den CT-Datensatz Vorverarbeitungsschritten, welche die Daten durch Segmentierung auf wesentliche Informationen in Form von Labein für Muskel und Blut reduzieren. Anschließend werden diese Label zur Registrierung mittels der Match-Cardinality-Metrik genutzt. Durch mehrmaliges Registrieren mit verschiedenen Initialisierungen ermitteln wir die im US-Bild sichtbare Standardebene. Wir evaluierten die Methode auf sieben US-Bildern von Standardebenen. Fünf davon wurden korrekt zugeordnet.
Epitaxial 2D SnSe2/ 2D WSe2 van der Waals Heterostructures.
Aretouli, Kleopatra Emmanouil; Tsoutsou, Dimitra; Tsipas, Polychronis; Marquez-Velasco, Jose; Aminalragia Giamini, Sigiava; Kelaidis, Nicolaos; Psycharis, Vassilis; Dimoulas, Athanasios
2016-09-01
van der Waals heterostructures of 2D semiconductor materials can be used to realize a number of (opto)electronic devices including tunneling field effect devices (TFETs). It is shown in this work that high quality SnSe2/WSe2 vdW heterostructure can be grown by molecular beam epitaxy on AlN(0001)/Si(111) substrates using a Bi2Se3 buffer layer. A valence band offset of 0.8 eV matches the energy gap of SnSe2 in such a way that the VB edge of WSe2 and the CB edge of SnSe2 are lined up, making this materials combination suitable for (nearly) broken gap TFETs. PMID:27537619
CVMAC 2D Program: A method of converting 3D to 2D
Lown, J.
1990-06-20
This paper presents the user with a method of converting a three- dimensional wire frame model into a technical illustration, detail, or assembly drawing. By using the 2D Program, entities can be mapped from three-dimensional model space into two-dimensional model space, as if they are being traced. Selected entities to be mapped can include circles, arcs, lines, and points. This program prompts the user to digitize the view to be mapped, specify the layers in which the new two-dimensional entities will reside, and select the entities, either by digitizing or windowing. The new two-dimensional entities are displayed in a small view which the program creates in the lower left corner of the drawing. 9 figs.
Interactive initialization of 2D/3D rigid registration
Gong, Ren Hui; Güler, Özgür; Kürklüoglu, Mustafa; Lovejoy, John; Yaniv, Ziv
2013-12-15
Purpose: Registration is one of the key technical components in an image-guided navigation system. A large number of 2D/3D registration algorithms have been previously proposed, but have not been able to transition into clinical practice. The authors identify the primary reason for the lack of adoption with the prerequisite for a sufficiently accurate initial transformation, mean target registration error of about 10 mm or less. In this paper, the authors present two interactive initialization approaches that provide the desired accuracy for x-ray/MR and x-ray/CT registration in the operating room setting. Methods: The authors have developed two interactive registration methods based on visual alignment of a preoperative image, MR, or CT to intraoperative x-rays. In the first approach, the operator uses a gesture based interface to align a volume rendering of the preoperative image to multiple x-rays. The second approach uses a tracked tool available as part of a navigation system. Preoperatively, a virtual replica of the tool is positioned next to the anatomical structures visible in the volumetric data. Intraoperatively, the physical tool is positioned in a similar manner and subsequently used to align a volume rendering to the x-ray images using an augmented reality (AR) approach. Both methods were assessed using three publicly available reference data sets for 2D/3D registration evaluation. Results: In the authors' experiments, the authors show that for x-ray/MR registration, the gesture based method resulted in a mean target registration error (mTRE) of 9.3 ± 5.0 mm with an average interaction time of 146.3 ± 73.0 s, and the AR-based method had mTREs of 7.2 ± 3.2 mm with interaction times of 44 ± 32 s. For x-ray/CT registration, the gesture based method resulted in a mTRE of 7.4 ± 5.0 mm with an average interaction time of 132.1 ± 66.4 s, and the AR-based method had mTREs of 8.3 ± 5.0 mm with interaction times of 58 ± 52 s. Conclusions: Based on the
2D Four-Channel Perfect Reconstruction Filter Bank Realized with the 2D Lattice Filter Structure
NASA Astrophysics Data System (ADS)
Sezen, S.; Ertüzün, A.
2006-12-01
A novel orthogonal 2D lattice structure is incorporated into the design of a nonseparable 2D four-channel perfect reconstruction filter bank. The proposed filter bank is obtained by using the polyphase decomposition technique which requires the design of an orthogonal 2D lattice filter. Due to constraint of perfect reconstruction, each stage of this lattice filter bank is simply parameterized by two coefficients. The perfect reconstruction property is satisfied regardless of the actual values of these parameters and of the number of the lattice stages. It is also shown that a separable 2D four-channel perfect reconstruction lattice filter bank can be constructed from the 1D lattice filter and that this is a special case of the proposed 2D lattice filter bank under certain conditions. The perfect reconstruction property of the proposed 2D lattice filter approach is verified by computer simulations.
2D to 3D transition of polymeric carbon nitride nanosheets
Chamorro-Posada, Pedro; Vázquez-Cabo, José; Martín-Ramos, Pablo; Martín-Gil, Jesús; Navas-Gracia, Luis M.; Dante, Roberto C.
2014-11-15
The transition from a prevalent turbostratic arrangement with low planar interactions (2D) to an array of polymeric carbon nitride nanosheets with stronger interplanar interactions (3D), occurring for samples treated above 650 °C, was detected by terahertz-time domain spectroscopy (THz-TDS). The simulated 3D material made of stacks of shifted quasi planar sheets composed of zigzagged polymer ribbons, delivered a XRD simulated pattern in relatively good agreement with the experimental one. The 2D to 3D transition was also supported by the simulation of THz-TDS spectra obtained from quantum chemistry calculations, in which the same broad bands around 2 THz and 1.5 THz were found for 2D and 3D arrays, respectively. This transition was also in accordance with the tightening of the interplanar distance probably due to an interplanar π bond contribution, as evidenced also by a broad absorption around 2.6 eV in the UV–vis spectrum, which appeared in the sample treated at 650 °C, and increased in the sample treated at 700 °C. The band gap was calculated for 1D and 2D cases. The value of 3.374 eV for the 2D case is, within the model accuracy and precision, in a relative good agreement with the value of 3.055 eV obtained from the experimental results. - Graphical abstract: 2D lattice mode vibrations and structural changes correlated with the so called “2D to 3D transition”. - Highlights: • A 2D to 3D transition has been detected for polymeric carbon nitride. • THz-TDS allowed us to discover and detect the 2D to 3D transition of polymeric carbon nitride. • We propose a structure for polymeric carbon nitride confirming it with THz-TDS.
Unusual dimensionality effects and surface charge density in 2D Mg(OH)2
Suslu, Aslihan; Wu, Kedi; Sahin, Hasan; Chen, Bin; Yang, Sijie; Cai, Hui; Aoki, Toshihiro; Horzum, Seyda; Kang, Jun; Peeters, Francois M.; Tongay, Sefaattin
2016-01-01
We present two-dimensional Mg(OH)2 sheets and their vertical heterojunctions with CVD-MoS2 for the first time as flexible 2D insulators with anomalous lattice vibration and chemical and physical properties. New hydrothermal crystal growth technique enabled isolation of environmentally stable monolayer Mg(OH)2 sheets. Raman spectroscopy and vibrational calculations reveal that the lattice vibrations of Mg(OH)2 have fundamentally different signature peaks and dimensionality effects compared to other 2D material systems known to date. Sub-wavelength electron energy-loss spectroscopy measurements and theoretical calculations show that Mg(OH)2 is a 6 eV direct-gap insulator in 2D, and its optical band gap displays strong band renormalization effects from monolayer to bulk, marking the first experimental confirmation of confinement effects in 2D insulators. Interestingly, 2D-Mg(OH)2 sheets possess rather strong surface polarization (charge) effects which is in contrast to electrically neutral h-BN materials. Using 2D-Mg(OH)2 sheets together with CVD-MoS2 in the vertical stacking shows that a strong change transfer occurs from n-doped CVD-MoS2 sheets to Mg(OH)2, naturally depleting the semiconductor, pushing towards intrinsic doping limit and enhancing overall optical performance of 2D semiconductors. Results not only establish unusual confinement effects in 2D-Mg(OH)2, but also offer novel 2D-insulating material with unique physical, vibrational, and chemical properties for potential applications in flexible optoelectronics. PMID:26846617
Unusual dimensionality effects and surface charge density in 2D Mg(OH)2
NASA Astrophysics Data System (ADS)
Suslu, Aslihan; Wu, Kedi; Sahin, Hasan; Chen, Bin; Yang, Sijie; Cai, Hui; Aoki, Toshihiro; Horzum, Seyda; Kang, Jun; Peeters, Francois M.; Tongay, Sefaattin
2016-02-01
We present two-dimensional Mg(OH)2 sheets and their vertical heterojunctions with CVD-MoS2 for the first time as flexible 2D insulators with anomalous lattice vibration and chemical and physical properties. New hydrothermal crystal growth technique enabled isolation of environmentally stable monolayer Mg(OH)2 sheets. Raman spectroscopy and vibrational calculations reveal that the lattice vibrations of Mg(OH)2 have fundamentally different signature peaks and dimensionality effects compared to other 2D material systems known to date. Sub-wavelength electron energy-loss spectroscopy measurements and theoretical calculations show that Mg(OH)2 is a 6 eV direct-gap insulator in 2D, and its optical band gap displays strong band renormalization effects from monolayer to bulk, marking the first experimental confirmation of confinement effects in 2D insulators. Interestingly, 2D-Mg(OH)2 sheets possess rather strong surface polarization (charge) effects which is in contrast to electrically neutral h-BN materials. Using 2D-Mg(OH)2 sheets together with CVD-MoS2 in the vertical stacking shows that a strong change transfer occurs from n-doped CVD-MoS2 sheets to Mg(OH)2, naturally depleting the semiconductor, pushing towards intrinsic doping limit and enhancing overall optical performance of 2D semiconductors. Results not only establish unusual confinement effects in 2D-Mg(OH)2, but also offer novel 2D-insulating material with unique physical, vibrational, and chemical properties for potential applications in flexible optoelectronics.
A comparative analysis of 2D and 3D CAD for calcifications in digital breast tomosynthesis
NASA Astrophysics Data System (ADS)
Acciavatti, Raymond J.; Ray, Shonket; Keller, Brad M.; Maidment, Andrew D. A.; Conant, Emily F.
2015-03-01
Many medical centers offer digital breast tomosynthesis (DBT) and 2D digital mammography acquired under the same compression (i.e., "Combo" examination) for screening. This paper compares a conventional 2D CAD algorithm (Hologic® ImageChecker® CAD v9.4) for calcification detection against a prototype 3D algorithm (Hologic® ImageChecker® 3D Calc CAD v1.0). Due to the newness of DBT, the development of this 3D CAD algorithm is ongoing, and it is currently not FDA-approved in the United States. For this study, DBT screening cases with suspicious calcifications were identified retrospectively at the University of Pennsylvania. An expert radiologist (E.F.C.) reviewed images with both 2D and DBT CAD marks, and compared the marks to biopsy results. Control cases with one-year negative follow-up were also studied; these cases either possess clearly benign calcifications or lacked calcifications. To allow the user to alter the sensitivity for cancer detection, an operating point is assigned to each CAD mark. As expected from conventional 2D CAD, increasing the operating point in 3D CAD increases sensitivity and reduces specificity. Additionally, we showed that some cancers are occult to 2D CAD at all operating points. By contrast, 3D CAD allows for detection of some cancers that are missed on 2D CAD. We also demonstrated that some non-cancerous CAD marks in 3D are not present at analogous locations in the 2D image. Hence, there are additional marks when using both 2D and 3D CAD in combination, leading to lower specificity than with conventional 2D CAD alone.
Low 2D:4D Values Are Associated with Video Game Addiction
Kornhuber, Johannes; Zenses, Eva-Maria; Lenz, Bernd; Stoessel, Christina; Bouna-Pyrrou, Polyxeni; Rehbein, Florian; Kliem, Sören; Mößle, Thomas
2013-01-01
Androgen-dependent signaling regulates the growth of the fingers on the human hand during embryogenesis. A higher androgen load results in lower 2D:4D (second digit to fourth digit) ratio values. Prenatal androgen exposure also impacts brain development. 2D:4D values are usually lower in males and are viewed as a proxy of male brain organization. Here, we quantified video gaming behavior in young males. We found lower mean 2D:4D values in subjects who were classified according to the CSAS-II as having at-risk/addicted behavior (n = 27) compared with individuals with unproblematic video gaming behavior (n = 27). Thus, prenatal androgen exposure and a hyper-male brain organization, as represented by low 2D:4D values, are associated with problematic video gaming behavior. These results may be used to improve the diagnosis, prediction, and prevention of video game addiction. PMID:24236143
Low 2D:4D values are associated with video game addiction.
Kornhuber, Johannes; Zenses, Eva-Maria; Lenz, Bernd; Stoessel, Christina; Bouna-Pyrrou, Polyxeni; Rehbein, Florian; Kliem, Sören; Mößle, Thomas
2013-01-01
Androgen-dependent signaling regulates the growth of the fingers on the human hand during embryogenesis. A higher androgen load results in lower 2D:4D (second digit to fourth digit) ratio values. Prenatal androgen exposure also impacts brain development. 2D:4D values are usually lower in males and are viewed as a proxy of male brain organization. Here, we quantified video gaming behavior in young males. We found lower mean 2D:4D values in subjects who were classified according to the CSAS-II as having at-risk/addicted behavior (n = 27) compared with individuals with unproblematic video gaming behavior (n = 27). Thus, prenatal androgen exposure and a hyper-male brain organization, as represented by low 2D:4D values, are associated with problematic video gaming behavior. These results may be used to improve the diagnosis, prediction, and prevention of video game addiction.
NASA Astrophysics Data System (ADS)
Chae, Dongho; Constantin, Peter; Wu, Jiahong
2014-09-01
We give an example of a well posed, finite energy, 2D incompressible active scalar equation with the same scaling as the surface quasi-geostrophic equation and prove that it can produce finite time singularities. In spite of its simplicity, this seems to be the first such example. Further, we construct explicit solutions of the 2D Boussinesq equations whose gradients grow exponentially in time for all time. In addition, we introduce a variant of the 2D Boussinesq equations which is perhaps a more faithful companion of the 3D axisymmetric Euler equations than the usual 2D Boussinesq equations.
Zhang, Yu; Choi, Sung-Wook; Xia, Younan
2012-02-27
Inverse opal scaffolds have recently emerged as a novel class of scaffolds with uniform and controllable pore sizes for tissue engineering to provide better nutrient transport, a uniform cell distribution, and an adjustable microenvironment for cell differentiation. However, when the pore size of the scaffold is much larger than the dimension of a cell, the cell actually encounters a local 2D environment and the void space associated with the pore can not be efficiently utilized. Here, we demonstrate that a truly 3D microenvironment can be created inside a pore by further functionalizing the as-prepared inverse opal scaffold with a second polymer by freeze-drying. The resultant inverse opal scaffold with hierarchically structured pores can enhance both cell proliferation and tissue infiltration.
Forces acting in quasi 2d emulsions
NASA Astrophysics Data System (ADS)
Orellana, Carlos; Lowensohn, Janna; Weeks, Eric
We study the forces in a quasi two dimensional emulsion system. Our samples are oil-in-water emulsions confined between two close-spaced parallel plates, so that the oil droplets are deformed into pancake shapes. By means of microscopy, we measure the droplet positions and their deformation, which we can relate to the contact forces due to surface tension. We improve over prior work in our lab, achieving a better force resolution. We use this result to measure and calibrate the viscous forces acting in our system, which fully determine all the forces on the droplets. Our results can be applied to study static configurations of emulsion, as well as faster flows.
Helical Quantum Edge Gears in 2D Topological Insulators
NASA Astrophysics Data System (ADS)
Chou, Yang-Zhi; Levchenko, Alex; Foster, Matthew
A remarkable and as-yet-unexploited aspect of topological insulator (TI) physics is the topology of the edge states, i.e. the fact that the edge liquid of a 2D TI forms a closed, unbreakable loop in the absence of electrical contacts or magnetic fields. We propose a novel experimental setup in which edge loops rotate as interlocking ``gears'' through Coulomb drag, in TIs with Rashba spin-orbit coupling. We show that two-terminal transport can measure the Luttinger liquid parameter K, a quantity that is otherwise notoriously difficult to measure. In the low-temperature (T --> 0) perfect drag regime, the conductance is (e2 / h) (2 K + 1) / (K + 1) . At higher T we predict a conductivity ~T - 4 K + 3 . Our results should trigger new experiments and may open a new venue for edge gear-based electronic devices.Ref: Phys. Rev. Lett. 115, 186404 (2015)
Interpretive 2-D treatment of scrape-off-layer plasmas
Umansky, M.; Allen, A.; Daughton, W.
1996-12-31
The width of the scrape-off-layer in a tokamak is determined by cross field transport. In Alcator C-mod the plasma parameters in the scrape-off-layer are measured at upstream and divertor plate locations. We solve a 2-D scrape-off-layer heat conduction equation in the flux geometry (as determined by EFIT) of the C-mod experiment. Bolometric measurements are utilized for the radiative loss term. We use the end wall probe measurements of electron temperature as a boundary condition and the fast scanning probe measurements of upstream temperature are treated as constraints to determine the cross field transport and thermal conductivity. Results are compared with 1-D onion-skin-model predictions.
Optimum design of 2D micro-angle sensor
NASA Astrophysics Data System (ADS)
Liu, Qinggang; Zhao, Heng; Lou, Xiaona; Jiang, Ningchuan; Hu, Xiaotang
2008-12-01
To improve dynamic measurement performance and resolution, an optimum design on two-dimensional (2D) micro-angle sensor based on optical internal-reflection method via critical-angle refractive index measurement is presented in the paper. The noise signals were filtered effectively by modulating laser-driven and demodulating in signal proceeding. The system's accuracy and response speed are improved further by using 16-bit high-precision AD converter and MSP430 CPU which present with a high-speed performance during signals processes such as fitting angle-voltage curve through specific arithmetic, full range and zero point calibration, filter, scaling transformation etc. The experiment results indicated that, dynamic signal measurement range can be up to +/-600arcsec, the measurement resolution can be better than 0.1arcsec, and the repeatability could be better than +/-0.5arcsec.
Fast and robust recognition and localization of 2D objects
NASA Astrophysics Data System (ADS)
Otterbach, Rainer; Gerdes, Rolf; Kammueller, R.
1994-11-01
The paper presents a vision system which provides a robust model-based identification and localization of 2-D objects in industrial scenes. A symbolic image description based on the polygonal approximation of the object silhouettes is extracted in video real time by the use of dedicated hardware. Candidate objects are selected from the model database using a time and memory efficient hashing algorithm. Any candidate object is submitted to the next computation stage which generates pose hypotheses by assigning model to image contours. Corresponding continuous measures of similarity are derived from the turning functions of the curves. Finally, the previous generated hypotheses are verified using a voting scheme in transformation space. Experimental results reveal the fault tolerance of the vision system with regard to noisy and split image contours as well as partial occlusion of objects. THe short cycle time and the easy adaptability of the vision system make it well suited for a wide variety of applications in industrial automation.
The seismic analyzer: interpreting and illustrating 2D seismic data.
Patel, Daniel; Giertsen, Christopher; Thurmond, John; Gjelberg, John; Gröller, M Eduard
2008-01-01
We present a toolbox for quickly interpreting and illustrating 2D slices of seismic volumetric reflection data. Searching for oil and gas involves creating a structural overview of seismic reflection data to identify hydrocarbon reservoirs. We improve the search of seismic structures by precalculating the horizon structures of the seismic data prior to interpretation. We improve the annotation of seismic structures by applying novel illustrative rendering algorithms tailored to seismic data, such as deformed texturing and line and texture transfer functions. The illustrative rendering results in multi-attribute and scale invariant visualizations where features are represented clearly in both highly zoomed in and zoomed out views. Thumbnail views in combination with interactive appearance control allows for a quick overview of the data before detailed interpretation takes place. These techniques help reduce the work of seismic illustrators and interpreters.
Flow past 2-D Hemispherical Rigid Canopies
NASA Astrophysics Data System (ADS)
Carnasciali, Maria-Isabel
2013-11-01
The flow past a 2-dimensional rigid hemispherical shape is investigated using PIV. Flow field measurements and images were generated with the use of a Thermoflow® apparatus. Results of this study are compared to prior work (APS DFD 2012 Session E9.00003) which employed CFD to investigate the flow in the near wake of hemispherical parachutes. The various sized gaps/open areas were positioned at distinct locations. The work presented here is part of a larger research project to investigate flow fields in deceleration devices and parachutes. Understanding the pitch-stability of parachutes is essential for accurate design and implementation of these deceleration devices but they present a difficult system to analyze. The flexibility of the parachute fabric results in large variations in the parachute geometry leading to complex fluid-structure interactions. Such flow, combined with flow through gaps and open areas, has been postulated to shed alternating vortices causing pitching/oscillations of the canopy. The results presented provide some insight into which geometric features affect vortex shedding and may enable the redesign of the baseline parachute to minimize instabilities.
Anisotropic magnetotelluric inversion using a mutual information constraint
NASA Astrophysics Data System (ADS)
Mandolesi, E.; Jones, A. G.
2012-12-01
In recent years, several authors pointed that the electrical conductivity of many subsurface structures cannot be described properly by a scalar field. With the development of field devices and techniques, data quality improved to the point that the anisotropy in conductivity of rocks (microscopic anisotropy) and tectonic structures (macroscopic anisotropy) cannot be neglected. Therefore a correct use of high quality data has to include electrical anisotropy and a correct interpretation of anisotropic data characterizes directly a non-negligible part of the subsurface. In this work we test an inversion routine that takes advantage of the classic Levenberg-Marquardt (LM) algorithm to invert magnetotelluric (MT) data generated from a bi-dimensional (2D) anisotropic domain. The LM method is routinely used in inverse problems due its performance and robustness. In non-linear inverse problems -such the MT problem- the LM method provides a spectacular compromise betwee quick and secure convergence at the price of the explicit computation and storage of the sensitivity matrix. Regularization in inverse MT problems has been used extensively, due to the necessity to constrain model space and to reduce the ill-posedness of the anisotropic MT problem, which makes MT inversions extremely challenging. In order to reduce non-uniqueness of the MT problem and to reach a model compatible with other different tomographic results from the same target region, we used a mutual information (MI) based constraint. MI is a basic quantity in information theory that can be used to define a metric between images, and it is routinely used in fields as computer vision, image registration and medical tomography, to cite some applications. We -thus- inverted for the model that best fits the anisotropic data and that is the closest -in a MI sense- to a tomographic model of the target area. The advantage of this technique is that the tomographic model of the studied region may be produced by any
Adaptation algorithms for 2-D feedforward neural networks.
Kaczorek, T
1995-01-01
The generalized weight adaptation algorithms presented by J.G. Kuschewski et al. (1993) and by S.H. Zak and H.J. Sira-Ramirez (1990) are extended for 2-D madaline and 2-D two-layer feedforward neural nets (FNNs).
Integrating Mobile Multimedia into Textbooks: 2D Barcodes
ERIC Educational Resources Information Center
Uluyol, Celebi; Agca, R. Kagan
2012-01-01
The major goal of this study was to empirically compare text-plus-mobile phone learning using an integrated 2D barcode tag in a printed text with three other conditions described in multimedia learning theory. The method examined in the study involved modifications of the instructional material such that: a 2D barcode was used near the text, the…
Efficient Visible Quasi-2D Perovskite Light-Emitting Diodes.
Byun, Jinwoo; Cho, Himchan; Wolf, Christoph; Jang, Mi; Sadhanala, Aditya; Friend, Richard H; Yang, Hoichang; Lee, Tae-Woo
2016-09-01
Efficient quasi-2D-structure perovskite light-emitting diodes (4.90 cd A(-1) ) are demonstrated by mixing a 3D-structured perovskite material (methyl ammonium lead bromide) and a 2D-structured perovskite material (phenylethyl ammonium lead bromide), which can be ascribed to better film uniformity, enhanced exciton confinement, and reduced trap density. PMID:27334788
Efficient Visible Quasi-2D Perovskite Light-Emitting Diodes.
Byun, Jinwoo; Cho, Himchan; Wolf, Christoph; Jang, Mi; Sadhanala, Aditya; Friend, Richard H; Yang, Hoichang; Lee, Tae-Woo
2016-09-01
Efficient quasi-2D-structure perovskite light-emitting diodes (4.90 cd A(-1) ) are demonstrated by mixing a 3D-structured perovskite material (methyl ammonium lead bromide) and a 2D-structured perovskite material (phenylethyl ammonium lead bromide), which can be ascribed to better film uniformity, enhanced exciton confinement, and reduced trap density.
ERIC Educational Resources Information Center
Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.
2001-01-01
Describes the Collegiate Results Instrument (CRI), which measures a range of collegiate outcomes for alumni 6 years after graduation. The CRI was designed to target alumni from institutions across market segments and assess their values, abilities, work skills, occupations, and pursuit of lifelong learning. (EV)
2D kinematic signatures of boxy/peanut bulges
NASA Astrophysics Data System (ADS)
Iannuzzi, Francesca; Athanassoula, E.
2015-07-01
We study the imprints of boxy/peanut structures on the 2D line-of-sight kinematics of simulated disc galaxies. The models under study belong to a family with varying initial gas fraction and halo triaxiality, plus few other control runs with different structural parameters; the kinematic information was extracted using the Voronoi-binning technique and parametrized up to the fourth order of a Gauss-Hermite series. Building on a previous work for the long-slit case, we investigate the 2D kinematic behaviour in the edge-on projection as a function of the boxy/peanut strength and position angle; we find that for the strongest structures the highest moments show characteristic features away from the mid-plane in a range of position angles. We also discuss the masking effect of a classical bulge and the ambiguity in discriminating kinematically this spherically symmetric component from a boxy/peanut bulge seen end-on. Regarding the face-on case, we extend existing results to encompass the effect of a second buckling and find that this phenomenon spurs an additional set of even deeper minima in the fourth moment. Finally, we show how the results evolve when inclining the disc away from perfectly edge-on and face-on. The behaviour of stars born during the course of the simulations is discussed and confronted to that of the pre-existing disc. The general aim of our study is providing a handle to identify boxy/peanut structures and their properties in latest generation Integral Field Unit observations of nearby disc galaxies.
2-D Finite Element Heat Conduction
1989-10-30
AYER is a finite element program which implicitly solves the general two-dimensional equation of thermal conduction for plane or axisymmetric bodies. AYER takes into account the effects of time (transient problems), in-plane anisotropic thermal conductivity, a three-dimensional velocity distribution, and interface thermal contact resistance. Geometry and material distributions are arbitrary, and input is via subroutines provided by the user. As a result, boundary conditions, material properties, velocity distributions, and internal power generation may be mademore » functions of, e.g., time, temperature, location, and heat flux.« less
Network models for 2D disordered superconductors
NASA Astrophysics Data System (ADS)
Kagalovsky, Victor; Horovitz, Baruch; Avishai, Yshai
2004-04-01
We study new random matrix symmetry classes which arise in models of non-interacting quasi-particles in disordered superconductors. Within the Altland-Zirnbauer classification scheme these are class C (with time-reversal symmetry broken and spin-rotaion invariance intact), and class D where both symmetries are broken. Preliminary studies of the two remaining symmetry classes CI and DIII are briefly mentioned. New results are presented pertaining to the 3d realization of class C, which, physically, corresponds to a layered superconductor.
NASA Technical Reports Server (NTRS)
Gelinas, R. J.; Doss, S. K.; Vajk, J. P.; Djomehri, J.; Miller, K.
1983-01-01
The mathematical background regarding the moving finite element (MFE) method of Miller and Miller (1981) is discussed, taking into account a general system of partial differential equations (PDE) and the amenability of the MFE method in two dimensions to code modularization and to semiautomatic user-construction of numerous PDE systems for both Dirichlet and zero-Neumann boundary conditions. A description of test problem results is presented, giving attention to aspects of single square wave propagation, and a solution of the heat equation.
Analytical inversion formula for uniformly attenuated fan-beam projections
Weng, Y.; Zeng, G.L.; Gullberg, G.T.
1997-04-01
In deriving algorithms to reconstruct single photon emission computed tomography (SPECT) projection data, it is important that the algorithm compensates for photon attenuation in order to obtain quantitative reconstruction results. A convolution backprojection algorithm was derived by Tretiak and Metz to reconstruct two-dimensional (2-D) transaxial slices from uniformly attenuated parallel-beam projections. Using transformation of coordinates, this algorithm can be modified to obtain a formulation useful to reconstruct uniformly attenuated fan-beam projections. Unlike that for parallel-beam projections, this formulation does not produce a filtered backprojection reconstruction algorithm but instead has a formulation that is an inverse integral operator with a spatially varying kernel. This algorithm thus requires more computation time than does the filtered backprojection reconstruction algorithm for the uniformly attenuated parallel-beam case. However, the fan-beam reconstructions demonstrate the same image quality as that of parallel-beam reconstructions.
Cooperative dynamics in ultrasoft 2D crystals
NASA Astrophysics Data System (ADS)
Sprakel, Joris; van der Meer, Berend; Dijkstra, Marjolein; van der Gucht, Jasper
2015-03-01
The creation, annihilation, and diffusion of defects in crystal lattices play an important role during crystal melting and deformation. Although it is well understood how defects form and react when crystals are subjected to external stresses, it remains unclear how crystals cope with internal stresses. We report a study in which we create a highly localized internal stress, by means of optical tweezing, in a crystal formed from micrometer-sized colloidal spheres and directly observe how the solid reacts using microscopy. We find that, even though the excitation is highly localized, a collective dance of colloidal particles results; these collective modes take the form of closed rings or open-ended strings, depending on the sequence of events which nucleate the rearrangements. Surprisingly, we find from Brownian Dynamics simulations that these cooperative dynamics are thermally-activated modes inherent to the crystal, and can even occur through a single, sufficiently large thermal fluctuation, resulting in the irreversible displacement of 100s of particles from their lattice sites.
Mechanical loading and the synthesis of 1,25(OH)2D in primary human osteoblasts.
van der Meijden, K; Bakker, A D; van Essen, H W; Heijboer, A C; Schulten, E A J M; Lips, P; Bravenboer, N
2016-02-01
local vitamin D metabolism in primary human osteoblasts. Our results suggest that 1,25(OH)2D3 and mechanical loading, both stimuli of the differentiation of osteoblasts, interact at the cellular level.
Efficient Inversion of Mult-frequency and Multi-Source Electromagnetic Data
Gary D. Egbert
2007-03-22
The project covered by this report focused on development of efficient but robust non-linear inversion algorithms for electromagnetic induction data, in particular for data collected with multiple receivers, and multiple transmitters, a situation extremely common in eophysical EM subsurface imaging methods. A key observation is that for such multi-transmitter problems each step in commonly used linearized iterative limited memory search schemes such as conjugate gradients (CG) requires solution of forward and adjoint EM problems for each of the N frequencies or sources, essentially generating data sensitivities for an N dimensional data-subspace. These multiple sensitivities allow a good approximation to the full Jacobian of the data mapping to be built up in many fewer search steps than would be required by application of textbook optimization methods, which take no account of the multiplicity of forward problems that must be solved for each search step. We have applied this idea to a develop a hybrid inversion scheme that combines features of the iterative limited memory type methods with a Newton-type approach using a partial calculation of the Jacobian. Initial tests on 2D problems show that the new approach produces results essentially identical to a Newton type Occam minimum structure inversion, while running more rapidly than an iterative (fixed regularization parameter) CG style inversion. Memory requirements, while greater than for something like CG, are modest enough that even in 3D the scheme should allow 3D inverse problems to be solved on a common desktop PC, at least for modest (~ 100 sites, 15-20 frequencies) data sets. A secondary focus of the research has been development of a modular system for EM inversion, using an object oriented approach. This system has proven useful for more rapid prototyping of inversion algorithms, in particular allowing initial development and testing to be conducted with two-dimensional example problems, before
2D materials and van der Waals heterostructures.
Novoselov, K S; Mishchenko, A; Carvalho, A; Castro Neto, A H
2016-07-29
The physics of two-dimensional (2D) materials and heterostructures based on such crystals has been developing extremely fast. With these new materials, truly 2D physics has begun to appear (for instance, the absence of long-range order, 2D excitons, commensurate-incommensurate transition, etc.). Novel heterostructure devices--such as tunneling transistors, resonant tunneling diodes, and light-emitting diodes--are also starting to emerge. Composed from individual 2D crystals, such devices use the properties of those materials to create functionalities that are not accessible in other heterostructures. Here we review the properties of novel 2D crystals and examine how their properties are used in new heterostructure devices.
Van der Waals stacked 2D layered materials for optoelectronics
NASA Astrophysics Data System (ADS)
Zhang, Wenjing; Wang, Qixing; Chen, Yu; Wang, Zhuo; Wee, Andrew T. S.
2016-06-01
The band gaps of many atomically thin 2D layered materials such as graphene, black phosphorus, monolayer semiconducting transition metal dichalcogenides and hBN range from 0 to 6 eV. These isolated atomic planes can be reassembled into hybrid heterostructures made layer by layer in a precisely chosen sequence. Thus, the electronic properties of 2D materials can be engineered by van der Waals stacking, and the interlayer coupling can be tuned, which opens up avenues for creating new material systems with rich functionalities and novel physical properties. Early studies suggest that van der Waals stacked 2D materials work exceptionally well, dramatically enriching the optoelectronics applications of 2D materials. Here we review recent progress in van der Waals stacked 2D materials, and discuss their potential applications in optoelectronics.
Kraidith, Kamonshanok; Svasti, Saovaros; Teerapornpuntakit, Jarinthorn; Vadolas, Jim; Chaimana, Rattana; Lapmanee, Sarawut; Suntornsaratoon, Panan; Krishnamra, Nateetip; Fucharoen, Suthat; Charoenphandhu, Narattaphol
2016-07-01
Previously, β-thalassemia, an inherited anemic disorder with iron overload caused by loss-of-function mutation of β-globin gene, has been reported to induce osteopenia and impaired whole body calcium metabolism, but the pathogenesis of aberrant calcium homeostasis remains elusive. Herein, we investigated how β-thalassemia impaired intestinal calcium absorption and whether it could be restored by administration of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] or hepcidin, the latter of which was the liver-derived antagonist of intestinal iron absorption. The results showed that, in hemizygous β-globin knockout (BKO) mice, the duodenal calcium transport was lower than that in wild-type littermates, and severity was especially pronounced in female mice. Both active and passive duodenal calcium fluxes in BKO mice were found to be less than those in normal mice. This impaired calcium transport could be restored by 7-day 1,25(OH)2D3 treatment. The 1,25(OH)2D3-induced calcium transport was diminished by inhibitors of calcium transporters, e.g., L-type calcium channel, NCX1, and PMCA1b, as well as vesicular transport inhibitors. Interestingly, the duodenal calcium transport exhibited an inverse correlation with transepithelial iron transport, which was markedly enhanced in thalassemic mice. Thus, 3-day subcutaneous hepcidin injection and acute direct hepcidin exposure in the Ussing chamber were capable of restoring the thalassemia-associated impairment of calcium transport; however, the positive effect of hepcidin on calcium transport was completely blocked by proteasome inhibitors MG132 and bortezomib. In conclusion, both 1,25(OH)2D3 and hepcidin could be used to alleviate the β-thalassemia-associated impairment of calcium absorption. Therefore, our study has shed light on the development of a treatment strategy to rescue calcium dysregulation in β-thalassemia. PMID:27245334
NASA Astrophysics Data System (ADS)
Córdova-Sintjago, Tania C.; Liu, Yue; Booth, Raymond G.
2015-02-01
To understand molecular determinants for ligand activation of the serotonin 5-HT2C G protein-coupled receptor (GPCR), a drug target for obesity and neuropsychiatric disorders, a 5-HT2C homology model was built according to an adrenergic β2 GPCR (β2AR) structure and validated using a 5-HT2B GPCR crystal structure. The models were equilibrated in a simulated phosphatidyl choline membrane for ligand docking and molecular dynamics studies. Ligands included (2S, 4R)-(-)-trans-4-(3'-bromo- and trifluoro-phenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalene-2-amine (3'-Br-PAT and 3'-CF3-PAT), a 5-HT2C agonist and inverse agonist, respectively. Distinct interactions of 3'-Br-PAT and 3'-CF3-PAT at the wild-type (WT) 5-HT2C receptor model were observed and experimental 5-HT2C receptor mutagenesis studies were undertaken to validate the modelling results. For example, the inverse agonist 3'-CF3-PAT docked deeper in the WT 5-HT2C binding pocket and altered the orientation of transmembrane helices (TM) 6 in comparison to the agonist 3'-Br-PAT, suggesting that changes in TM orientation that result from ligand binding impact function. For both PATs, mutation of 5-HT2C residues S3.36, T3.37, and F5.47 to alanine resulted in significantly decreased affinity, as predicted from modelling results. It was concluded that upon PAT binding, 5-HT2C residues T3.37 and F5.47 in TMs 3 and 5, respectively, engage in inter-helical interactions with TMs 4 and 6, respectively. The movement of TMs 5 and 6 upon agonist and inverse agonist ligand binding observed in the 5-HT2C receptor modelling studies was similar to movements reported for the activation and deactivation of the β2AR, suggesting common mechanisms among aminergic neurotransmitter GPCRs.
NASA Astrophysics Data System (ADS)
Revil, A.
2015-12-01
Geological expertise and petrophysical relationships can be brought together to provide prior information while inverting multiple geophysical datasets. The merging of such information can result in more realistic solution in the distribution of the model parameters, reducing ipse facto the non-uniqueness of the inverse problem. We consider two level of heterogeneities: facies, described by facies boundaries and heteroegenities inside each facies determined by a correlogram. In this presentation, we pose the geophysical inverse problem in terms of Gaussian random fields with mean functions controlled by petrophysical relationships and covariance functions controlled by a prior geological cross-section, including the definition of spatial boundaries for the geological facies. The petrophysical relationship problem is formulated as a regression problem upon each facies. The inversion of the geophysical data is performed in a Bayesian framework. We demonstrate the usefulness of this strategy using a first synthetic case for which we perform a joint inversion of gravity and galvanometric resistivity data with the stations located at the ground surface. The joint inversion is used to recover the density and resistivity distributions of the subsurface. In a second step, we consider the possibility that the facies boundaries are deformable and their shapes are inverted as well. We use the level set approach to perform such deformation preserving prior topological properties of the facies throughout the inversion. With the help of prior facies petrophysical relationships and topological characteristic of each facies, we make posterior inference about multiple geophysical tomograms based on their corresponding geophysical data misfits. The method is applied to a second synthetic case showing that we can recover the heterogeneities inside the facies, the mean values for the petrophysical properties, and, to some extent, the facies boundaries using the 2D joint inversion of
Estrogen-Induced Cholestasis Leads to Repressed CYP2D6 Expression in CYP2D6-Humanized Mice
Pan, Xian
2015-01-01
Cholestasis activates bile acid receptor farnesoid X receptor (FXR) and subsequently enhances hepatic expression of small heterodimer partner (SHP). We previously demonstrated that SHP represses the transactivation of cytochrome P450 2D6 (CYP2D6) promoter by hepatocyte nuclear factor (HNF) 4α. In this study, we investigated the effects of estrogen-induced cholestasis on CYP2D6 expression. Estrogen-induced cholestasis occurs in subjects receiving estrogen for contraception or hormone replacement, or in susceptible women during pregnancy. In CYP2D6-humanized transgenic (Tg-CYP2D6) mice, cholestasis triggered by administration of 17α-ethinylestradiol (EE2) at a high dose led to 2- to 3-fold decreases in CYP2D6 expression. This was accompanied by increased hepatic SHP expression and subsequent decreases in the recruitment of HNF4α to CYP2D6 promoter. Interestingly, estrogen-induced cholestasis also led to increased recruitment of estrogen receptor (ER) α, but not that of FXR, to Shp promoter, suggesting a predominant role of ERα in transcriptional regulation of SHP in estrogen-induced cholestasis. EE2 at a low dose (that does not cause cholestasis) also increased SHP (by ∼50%) and decreased CYP2D6 expression (by 1.5-fold) in Tg-CYP2D6 mice, the magnitude of differences being much smaller than that shown in EE2-induced cholestasis. Taken together, our data indicate that EE2-induced cholestasis increases SHP and represses CYP2D6 expression in Tg-CYP2D6 mice in part through ERα transactivation of Shp promoter. PMID:25943116
Optimized arrays for 2-D resistivity survey lines with a large number of electrodes
NASA Astrophysics Data System (ADS)
Loke, M. H.; Wilkinson, P. B.; Chambers, J. E.; Uhlemann, S. S.; Sorensen, J. P. R.
2015-01-01
Previous studies show that optimized arrays generated using the 'Compare R' method have significantly better resolution than conventional arrays. This method determines the optimum set of arrays by selecting those that give the maximum model resolution. The number of possible arrays (the comprehensive data set) increases with the fourth power of the number of electrodes. The optimization method faces practical limitations for 2-D survey lines with more than 60 electrodes where the number of possible arrays exceeds a million. Several techniques are proposed to reduce the calculation time for such survey lines. A single-precision version of the 'Compare R' algorithm using a new ranking function reduces the calculation time by two to eight times while providing results similar to the double-precision version. Recent improvements in computer GPU technology can reduce the calculation time by about seven times. The calculation time is reduced by half by using the fact that arrays that are symmetrical about the center of the line produce identical changes in the model resolution values. It is further reduced by more than thirty times by calculating the Sherman-Morrison update for all the possible two-electrode combinations, which are then used to calculate the model resolution values for the four-electrode arrays. The calculation time is reduced by more then ten times by using a subset of the comprehensive data set consisting of only symmetrical arrays. Tests with a synthetic model and field data set show that optimized arrays derived from this subset produce inversion models with differences of less than 10% from those derived using the full comprehensive data set. The optimized data sets produced models that are more accurate than the Wenner-Schlumberger array data sets in all the tests.
Integral inversion to Fraunhofer diffraction for particle sizing.
Cao, Zhang; Xu, Lijun; Ding, Jie
2009-09-01
A new solution to the inversion of Fraunhofer diffraction for particle sizing was introduced. Compared with the well-known Chin-Shifrin inversion, it is an inversion of the form of integral transform and less sensitive to noise. Simulation results with noise-contaminated data were obtained and showed that the new inversion is better than the Chin-Shifrin inversion. Especially when the particle diameter was small, the new inversion still performed well, whereas the Chin-Shifrin inversion did not converge.
Height-dependent transition from 3-D to 2-D turbulence in the hurricane boundary layer
NASA Astrophysics Data System (ADS)
Byrne, David; Zhang, Jun A.
2013-04-01
Here we show, from in situ aircraft measurements in the hurricane boundary layer, a height-dependent transition of the flow from 3-D to 2-D turbulence. This marks a fundamental change in the energy dynamics of the hurricane boundary layer due to the fact that in 3-D, energy flows downscale from larger to smaller scales, whereas in 2-D, it flows upscale, from smaller to larger scales. These results represent the first measurement of the 2-D upscale energy flux in the atmosphere and also the first to characterize the transition from 3-D to 2-D. It is shown that the large-scale parent vortex may gain energy directly from small scales in tropical cyclones.
Raman 2D-band splitting in graphene: theory and experiment.
Frank, Otakar; Mohr, Marcel; Maultzsch, Janina; Thomsen, Christian; Riaz, Ibtsam; Jalil, Rashid; Novoselov, Kostya S; Tsoukleri, Georgia; Parthenios, John; Papagelis, Konstantinos; Kavan, Ladislav; Galiotis, Costas
2011-03-22
We present a systematic experimental and theoretical study of the two-phonon (2D) Raman scattering in graphene under uniaxial tension. The external perturbation unveils that the 2D mode excited with 785 nm has a complex line-shape mainly due to the contribution of two distinct double resonance scattering processes (inner and outer) in the Raman signal. The splitting depends on the direction of the applied strain and the polarization of the incident light. The results give new insight into the nature of the 2D band and have significant implications for the use of graphene as reinforcement in composites since the 2D mode is crucial to assess how effectively graphene uptakes an applied stress or strain.
Relationship between Entrainment and Static Pressure Field on 2-D Jets.
NASA Astrophysics Data System (ADS)
Kimura, M.; Ono, K.; Saima, A.
1996-11-01
It is well know that entrainment carried out in wakes and jets. This experimental study aimes at investigation the relationship between the entrainment and the pressure field in 2-D jet. The 2-D jet was generated by 2-D rectangular wind tunnel. The velocity and prressure fields were observed in order to investigate the free shear layer of jet. These value were measured by the x type hot-wire anemometer, LDV and the newly developed static pressure probe. Jet diffusion process is visualized by smoke wire method. The result of the experiment was that the static pressure fluctuated intensively, and was negative mean value because of the velocity intermittence in the free shear layer of the 2-D jet. It seems reasonable to suppose that entrainment occurs owing to the negative static pressure by the eddy motion and large scale convection in the free shear layer.
Lee, Chien-Wei; Hwu, Jenn-Gwo
2013-10-15
We derive a statistical physics model of two-dimensional electron gas (2DEG) and propose an accurate approximation method for calculating the quantum-mechanical effects of metal-oxide-semiconductor (MOS) structure in accumulation and strong inversion regions. We use an exponential surface potential approximation in solving the quantization energy levels and derive the function of density of states in 2D to 3D transition region by applying uncertainty principle and Schrödinger equation in k-space. The simulation results show that our approximation method and theory of density of states solve the two major problems of previous researches: the non-negligible error caused by the linear potential approximation and the inconsistency of density of states and carrier distribution in 2D to 3D transition region.
2D optoacoustic array for high resolution imaging
NASA Astrophysics Data System (ADS)
Ashkenazi, S.; Witte, R. S.; Kim, K.; Huang, S.-W.; Hou, Y.; O'Donnell, M.
2006-02-01
An optoacoustic detector denotes the detection of acoustic signals by optical devices. Recent advances in fabrication techniques and the availability of high power tunable laser sources have greatly accelerated the development of efficient optoacoustic detectors. The unique advantages of optoacoustic technology are of special interest in applications that require high resolution imaging. For these applications optoacoustic technology enables high frequency transducer arrays with element size on the order of 10 μm. Laser generated ultrasound (photoacoustic effect) has been studied since the early observations of A.G. Bell (1880) of audible sound generated by light absorption . Modern studies have demonstrated the use of the photoacoustic effect to form a versatile imaging modality for medical and biological applications. A short laser pulse illuminates a tissue creating rapid thermal expansion and acoustic emission. Detection of the resulting acoustic field by an array enables the imaging of the tissue optical absorption using ultrasonic imaging methods. We present an integrated imaging system that employs photoacoustic sound generation and 2D optoacoustic reception. The optoacoustic receiver consists of a thin polymer Fabry-Perot etalon. The etalon is an optical resonator of a high quality factor (Q = 750). The relatively low elasticity modulus of the polymer and the high Q-factor of the resonator combine to yield high ultrasound sensitivity. The etalon thickness (10 μm) was optimized for wide bandwidth (typically above 50 MHz). An optical scanning and focusing system is used to create a large aperture and high density 2D ultrasonic receiver array. High resolution 3D images of phantom targets and biological tissue samples were obtained.
2D foam coarsening in a microfluidic system
NASA Astrophysics Data System (ADS)
Marchalot, J.; Lambert, J.; Cantat, I.; Tabeling, P.; Jullien, M.-C.
2008-09-01
We report an experimental study of 2D microfoam coarsening confined in a micrometer scale geometry, the typical bubbles diameter being of the order of 50-100 μm. These experiments raise both fundamental and applicative issues. For applicative issues: what is the typical time of foam ageing (for a polydisperse foam) in microsystems in scope of gas pocket storage in lab-on-a-chips? Experimental results show that a typical time of 2-3 mn is found, leading to the possibility of short-time storing, depending on the application. For fundamental interests, 2D foam ageing is generally described by von Neumann's law (von Neumann J., Metal Interfaces (American Society of Metals, Cleveland) 1952, p. 108) which is based on the hypothesis that bubbles are separated by thin films. Does this hypothesis still hold for foams confined in a 40 μm height geometry? This problematic is analyzed and it is shown that von Neumann's law still holds but that the diffusion coefficient involved in this law is modified by the confinement which imposes a curvature radius at Plateau borders. More precisely, it is shown that the liquid fraction is high on a film cross-section, in contrast with macrometric experiments where drainage occurs. An analytical description of the diffusion is developped taking into account the fact that soap film height is only a fraction of the cell height. While most of microfoams are flowing, the experimental set-up we describe leads to the achievement of a motionless confined microfoam.
E-2D Advanced Hawkeye: primary flight display
NASA Astrophysics Data System (ADS)
Paolillo, Paul W.; Saxena, Ragini; Garruba, Jonathan; Tripathi, Sanjay; Blanchard, Randy
2006-05-01
This paper is a response to the challenge of providing a large area avionics display for the E-2D AHE aircraft. The resulting display design provides a pilot with high-resolution visual information content covering an image area of almost three square feet (Active Area of Samsung display = 33.792cm x 27.0336 cm = 13.304" x 10.643" = 141.596 square inches = 0.983 sq. ft x 3 = 2.95 sq. ft). The avionics display application, design and performance being described is the Primary Flight Display for the E-2D Advanced Hawkeye aircraft. This cockpit display has a screen diagonal size of 17 inches. Three displays, with minimum bezel width, just fit within the available instrument panel area. The significant design constraints of supporting an upgrade installation have been addressed. These constraints include a display image size that is larger than the mounting opening in the instrument panel. This, therefore, requires that the Electromagnetic Interference (EMI) window, LCD panel and backlight all fit within the limited available bezel depth. High brightness and a wide dimming range are supported with a dual mode Cold Cathode Fluorescent Tube (CCFT) and LED backlight. Packaging constraints dictated the use of multiple U shaped fluorescent lamps in a direct view backlight design for a maximum display brightness of 300 foot-Lamberts. The low intensity backlight levels are provided by remote LEDs coupled through a fiber optic mesh. This architecture generates luminous uniformity within a minimum backlight depth. Cross-cockpit viewing is supported with ultra-wide field-of-view performance including contrast and the color stability of an advanced LCD cell design supports. Display system design tradeoffs directed a priority to high optical efficiency for minimum power and weight.
A novel adenoviral vector-mediated mouse model of Charcot-Marie-Tooth type 2D (CMT2D).
Seo, Ah Jung; Shin, Youn Ho; Lee, Seo Jin; Kim, Doyeun; Park, Byung Sun; Kim, Sunghoon; Choi, Kyu Ha; Jeong, Na Young; Park, Chan; Jang, Ji-Yeon; Huh, Youngbuhm; Jung, Junyang
2014-04-01
Charcot-Marie-Tooth disease type 2D is a hereditary axonal and glycyl-tRNA synthetase (GARS)-associated neuropathy that is caused by a mutation in GARS. Here, we report a novel GARS-associated mouse neuropathy model using an adenoviral vector system that contains a neuronal-specific promoter. In this model, we found that wild-type GARS is distributed to peripheral axons, dorsal root ganglion (DRG) cell bodies, central axon terminals, and motor neuron cell bodies. In contrast, GARS containing a G240R mutation was localized in DRG and motor neuron cell bodies, but not axonal regions, in vivo. Thus, our data suggest that the disease-causing G240R mutation may result in a distribution defect of GARS in peripheral nerves in vivo. Furthermore, a distributional defect may be associated with axonal degradation in GARS-associated neuropathies.
Inverse magnetorheological fluids.
Rodríguez-Arco, L; López-López, M T; Zubarev, A Y; Gdula, K; Durán, J D G
2014-09-01
We report a new kind of field-responsive fluid consisting of suspensions of diamagnetic (DM) and ferromagnetic (FM) microparticles in ferrofluids. We designate them as inverse magnetorheological (IMR) fluids for analogy with inverse ferrofluids (IFFs). Observations on the particle self-assembly in IMR fluids upon magnetic field application showed that DM and FM microparticles were assembled into alternating chains oriented along the field direction. We explain such assembly on the basis of the dipolar interaction energy between particles. We also present results on the rheological properties of IMR fluids and, for comparison, those of IFFs and bidispersed magnetorheological (MR) fluids. Interestingly, we found that upon magnetic field application, the rheological properties of IMR fluids were enhanced with respect to bidispersed MR fluids with the same FM particle concentration, by an amount greater than the sum of the isolated contribution of DM particles. Furthermore, the field-induced yield stress was moderately increased when up to 30% of the total FM particle content was replaced with DM particles. Beyond this point, the dependence of the yield stress on the DM content was non-monotonic, as expected for FM concentrations decreasing to zero. We explain these synergistic results by two separate phenomena: the formation of exclusion areas for FM particles due to the perturbation of the magnetic field by DM particles and the dipole-dipole interaction between DM and FM particles, which enhances the field-induced structures. Based on the second phenomenon, we present a theoretical model for the yield stress that semi-quantitatively predicts the experimental results. PMID:25022363
2-D Path Corrections for Local and Regional Coda Waves: A Test of Transportability
Mayeda, K M; Malagnini, L; Phillips, W S; Walter, W R; Dreger, D S; Morasca, P
2005-07-13
Reliable estimates of the seismic source spectrum are necessary for accurate magnitude, yield, and energy estimation. In particular, how seismic radiated energy scales with increasing earthquake size has been the focus of recent debate within the community and has direct implications on earthquake source physics studies as well as hazard mitigation. The 1-D coda methodology of Mayeda et al. [2003] has provided the lowest variance estimate of the source spectrum when compared against traditional approaches that use direct S-waves, thus making it ideal for networks that have sparse station distribution. The 1-D coda methodology has been mostly confined to regions of approximately uniform complexity. For larger, more geophysically complicated regions, 2-D path corrections may be required. We will compare performance of 1-D versus 2-D path corrections in a variety of regions. First, the complicated tectonics of the northern California region coupled with high quality broadband seismic data provides for an ideal ''apples-to-apples'' test of 1-D and 2-D path assumptions on direct waves and their coda. Next, we will compare results for the Italian Alps using high frequency data from the University of Genoa. For Northern California, we used the same station and event distribution and compared 1-D and 2-D path corrections and observed the following results: (1) 1-D coda results reduced the amplitude variance relative to direct S-waves by roughly a factor of 8 (800%); (2) Applying a 2-D correction to the coda resulted in up to 40% variance reduction from the 1-D coda results; (3) 2-D direct S-wave results, though better than 1-D direct waves, were significantly worse than the 1-D coda. We found that coda-based moment-rate source spectra derived from the 2-D approach were essentially identical to those from the 1-D approach for frequencies less than {approx}0.7-Hz, however for the high frequencies (0.7 {le} f {le} 8.0-Hz), the 2-D approach resulted in inter-station scatter
Prediction of a strain-tunable 2D Topological Dirac semimetal in monolayers of black phosphorus
NASA Astrophysics Data System (ADS)
Zhang, Xiuwen; Liu, Qihang; Zunger, Alex; Theory Team
2015-03-01
N-dimensional Topological Nonmetals (TNM) such as N = 2D HgTe/CdTe quantum wells or N = 3D Bi2Se3 have a finite (often tiny) band gap between occupied and unoccupied bands, and show conductive Dirac cones in their N-1 dimensional geometric boundaries. On the other hand, examples of topological semimetals (TSM) are known for 3D solids (Cd3As2) where they have Dirac cones in the 3D system itself. Using density functional calculation of bands and the topological invariant Z2 we predict the existence of 2D topological Dirac semimetal in few monolayers of strain tuned black phosphorus (BP), with Dirac cones induced by band inversion. The band structures of few monolayers and bulk crystal of BP under a few percent biaxial and uniaxial strains were calculated using state-of-art electronic structure methods. The critical strain of the transition to TSM was found to decrease as the layer thickness increases. We will discuss the protection of the Dirac cones by the crystalline symmetry in the 2D TSM and the manipulation of crystalline symmetry, which induces further topological phase transitions. Supported by the NSF-DMREF-13-34170.
THE CONTOUR METHOD: SIMPLE 2-D MAPPING OF RESIDUAL STRESSES
M. PRIME; A. GONZALES
2000-06-01
We present an entirely new method for measuring residual stress that is extremely simple to apply yet more powerful than existing techniques. In this method, a part is carefully cut in two. The contour of the resulting new surface is measured to determine the displacements normal to the surface caused by the release of the residual stresses. Analytically, the opposite of these measured displacements are applied as boundary conditions to the surface in a finite element model. By Bueckner's superposition principle, this gives the original residual stresses normal to the plane of the cut. Unlike other relaxation methods for measuring residual stress, the measured data can be used to solve directly for the stresses without a tedious inversion technique. At the same time, an arbitrary two-dimensional variation in stresses can be determined. We demonstrate the method on a steel specimen with a known residual stress profile.
NASA Astrophysics Data System (ADS)
Jackiewicz, Jason
2009-09-01
With the rapid advances in sophisticated solar modeling and the abundance of high-quality solar pulsation data, efficient and robust inversion techniques are crucial for seismic studies. We present some aspects of an efficient Fourier Optimally Localized Averaging (OLA) inversion method with an example applied to time-distance helioseismology.
Jackiewicz, Jason
2009-09-16
With the rapid advances in sophisticated solar modeling and the abundance of high-quality solar pulsation data, efficient and robust inversion techniques are crucial for seismic studies. We present some aspects of an efficient Fourier Optimally Localized Averaging (OLA) inversion method with an example applied to time-distance helioseismology.
ERIC Educational Resources Information Center
Bedard, Catherine; Belin, Pascal
2004-01-01
Voice is the carrier of speech but is also an ''auditory face'' rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a ''voice inversion effect,'' by analogy to the classical ''face inversion effect,'' which could support the hypothesis of a voice-specific module. Experiment 1 consisted…
An application of Ray + Born inversion on real data
Forgues, E.; Beukelaar, P. de; Coppens, F.; Richard, V.; Lambare, G.
1994-12-31
The authors present a linearized 2D acoustic and elastic multiparameter inversion of real marine seismic reflection data from the Gulf of Mexico. They solve the forward problem by a combination of Ray Theory and Born approximation. It fully takes advantage of efficiency of ray tracing in terms of computing, cost and physical comprehension. Lateral variations of background velocities can be introduced in the 2D ray tracing algorithm and a 2.5D approximation is done in order to take into account 3D propagation. The multiparameter inversion method is based on minimization of a weighted cost function. This weighted cost function is estimated from parameters associated with Ray and Paraxial Ray Theory and is introduced in order to diagonalize approximately the Hessian. This form of the Hessian allows the study of spatial resolution and conditioning of inversion.
Ojeda, Manuel; Li, Anwu; Nabar, Rahul P.; Nilekar, Anand U.; Mavrikakis, Manos; Iglesia, Enrique
2010-11-25
H2/D2 isotope effects on Fischer-Tropsch synthesis (FTS) rate and selectivity are examined here by combining measured values on Fe and Co at conditions leading to high C5+ yields with theoretical estimates on model Fe(110) and Co(0001) surfaces with high coverages of chemisorbed CO (CO*). Inverse isotope effects (rH/rD < 1) are observed on Co and Fe catalysts as a result of compensating thermodynamic (H2 dissociation to H*; H* addition to CO* species to form HCO*) and kinetic (H* reaction with HCO*) isotope effects. These isotopic effects and their rigorous mechanistic interpretation confirm the prevalence of H-assisted CO dissociation routes on both Fe and Co catalysts, instead of unassisted pathways that would lead to similar rates with H2 and D2 reactants. The small contributions from unassisted pathways to CO conversion rates on Fe are indeed independent of the dihydrogen isotope, as is also the case for the rates of primary reactions that form CO2 as the sole oxygen rejection route in unassisted CO dissociation paths. Isotopic effects on the selectivity to C5+ and CH4 products are small, and D2 leads to a more paraffinic product than does H2, apparently because it leads to preference for chain termination via hydrogen addition over abstraction. These results are consistent with FTS pathways limited by H-assisted CO dissociation on both Fe and Co and illustrate the importance of thermodynamic contributions to inverse isotope effects for reactions involving quasi-equilibrated H2 dissociation and the subsequent addition of H* in hydrogenation catalysis, as illustrated here by theory and experiment for the specific case of CO hydrogenation.
2D electron cyclotron emission imaging at ASDEX Upgrade (invited)
Classen, I. G. J.; Boom, J. E.; Vries, P. C. de; Suttrop, W.; Schmid, E.; Garcia-Munoz, M.; Schneider, P. A.; Tobias, B.; Domier, C. W.; Luhmann, N. C. Jr.; Donne, A. J. H.; Jaspers, R. J. E.; Park, H. K.; Munsat, T.
2010-10-15
The newly installed electron cyclotron emission imaging diagnostic on ASDEX Upgrade provides measurements of the 2D electron temperature dynamics with high spatial and temporal resolution. An overview of the technical and experimental properties of the system is presented. These properties are illustrated by the measurements of the edge localized mode and the reversed shear Alfven eigenmode, showing both the advantage of having a two-dimensional (2D) measurement, as well as some of the limitations of electron cyclotron emission measurements. Furthermore, the application of singular value decomposition as a powerful tool for analyzing and filtering 2D data is presented.
Recent advances in 2D materials for photocatalysis.
Luo, Bin; Liu, Gang; Wang, Lianzhou
2016-04-01
Two-dimensional (2D) materials have attracted increasing attention for photocatalytic applications because of their unique thickness dependent physical and chemical properties. This review gives a brief overview of the recent developments concerning the chemical synthesis and structural design of 2D materials at the nanoscale and their applications in photocatalytic areas. In particular, recent progress on the emerging strategies for tailoring 2D material-based photocatalysts to improve their photo-activity including elemental doping, heterostructure design and functional architecture assembly is discussed.
Wake Vortex Inverse Model User's Guide
NASA Technical Reports Server (NTRS)
Lai, David; Delisi, Donald
2008-01-01
NorthWest Research Associates (NWRA) has developed an inverse model for inverting landing aircraft vortex data. The data used for the inversion are the time evolution of the lateral transport position and vertical position of both the port and starboard vortices. The inverse model performs iterative forward model runs using various estimates of vortex parameters, vertical crosswind profiles, and vortex circulation as a function of wake age. Forward model predictions of lateral transport and altitude are then compared with the observed data. Differences between the data and model predictions guide the choice of vortex parameter values, crosswind profile and circulation evolution in the next iteration. Iterations are performed until a user-defined criterion is satisfied. Currently, the inverse model is set to stop when the improvement in the rms deviation between the data and model predictions is less than 1 percent for two consecutive iterations. The forward model used in this inverse model is a modified version of the Shear-APA model. A detailed description of this forward model, the inverse model, and its validation are presented in a different report (Lai, Mellman, Robins, and Delisi, 2007). This document is a User's Guide for the Wake Vortex Inverse Model. Section 2 presents an overview of the inverse model program. Execution of the inverse model is described in Section 3. When executing the inverse model, a user is requested to provide the name of an input file which contains the inverse model parameters, the various datasets, and directories needed for the inversion. A detailed description of the list of parameters in the inversion input file is presented in Section 4. A user has an option to save the inversion results of each lidar track in a mat-file (a condensed data file in Matlab format). These saved mat-files can be used for post-inversion analysis. A description of the contents of the saved files is given in Section 5. An example of an inversion input
Cho, Jungyeon
2011-05-13
Electron magnetohydrodynamics (EMHD) provides a fluidlike description of small-scale magnetized plasmas. An EMHD wave propagates along magnetic field lines. The direction of propagation can be either parallel or antiparallel to the magnetic field lines. We numerically study propagation of three-dimensional (3D) EMHD wave packets moving in one direction. We obtain two major results. (1) Unlike its magnetohydrodynamic (MHD) counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave packets traveling in one direction create opposite-traveling wave packets via self-interaction and cascade energy to smaller scales. (2) EMHD wave packets traveling in one direction clearly exhibit inverse energy cascade. We find that the latter is due to conservation of magnetic helicity. We compare inverse energy cascade in 3D EMHD turbulence and two-dimensional (2D) hydrodynamic turbulence.
PLAN2D - A PROGRAM FOR ELASTO-PLASTIC ANALYSIS OF PLANAR FRAMES
NASA Technical Reports Server (NTRS)
Lawrence, C.
1994-01-01
PLAN2D is a FORTRAN computer program for the plastic analysis of planar rigid frame structures. Given a structure and loading pattern as input, PLAN2D calculates the ultimate load that the structure can sustain before collapse. Element moments and plastic hinge rotations are calculated for the ultimate load. The location of hinges required for a collapse mechanism to form are also determined. The program proceeds in an iterative series of linear elastic analyses. After each iteration the resulting elastic moments in each member are compared to the reserve plastic moment capacity of that member. The member or members that have moments closest to their reserve capacity will determine the minimum load factor and the site where the next hinge is to be inserted. Next, hinges are inserted and the structural stiffness matrix is reformulated. This cycle is repeated until the structure becomes unstable. At this point the ultimate collapse load is calculated by accumulating the minimum load factor from each previous iteration and multiplying them by the original input loads. PLAN2D is based on the program STAN, originally written by Dr. E.L. Wilson at U.C. Berkeley. PLAN2D has several limitations: 1) Although PLAN2D will detect unloading of hinges it does not contain the capability to remove hinges; 2) PLAN2D does not allow the user to input different positive and negative moment capacities and 3) PLAN2D does not consider the interaction between axial and plastic moment capacity. Axial yielding and buckling is ignored as is the reduction in moment capacity due to axial load. PLAN2D is written in FORTRAN and is machine independent. It has been tested on an IBM PC and a DEC MicroVAX. The program was developed in 1988.
3D-2D registration of cerebral angiograms based on vessel directions and intensity gradients
NASA Astrophysics Data System (ADS)
Mitrovic, Uroš; Špiclin, Žiga; Štern, Darko; Markelj, Primož; Likar, Boštjan; Miloševic, Zoran; Pernuš, Franjo
2012-02-01
Endovascular treatment of cerebral aneurysms and arteriovenous malformations (AVM) involves navigation of a catheter through the femoral artery and vascular system to the site of pathology. Intra-interventional navigation is done under the guidance of one or at most two two-dimensional (2D) X-ray fluoroscopic images or 2D digital subtracted angiograms (DSA). Due to the projective nature of 2D images, the interventionist needs to mentally reconstruct the position of the catheter in respect to the three-dimensional (3D) patient vasculature, which is not a trivial task. By 3D-2D registration of pre-interventional 3D images like CTA, MRA or 3D-DSA and intra-interventional 2D images, intra-interventional tools such as catheters can be visualized on the 3D model of patient vasculature, allowing easier and faster navigation. Such a navigation may consequently lead to the reduction of total ionizing dose and delivered contrast medium. In the past, development and evaluation of 3D-2D registration methods for endovascular treatments received considerable attention. The main drawback of these methods is that they have to be initialized rather close to the correct position as they mostly have a rather small capture range. In this paper, a novel registration method that has a higher capture range and success rate is proposed. The proposed method and a state-of-the-art method were tested and evaluated on synthetic and clinical 3D-2D image-pairs. The results on both databases indicate that although the proposed method was slightly less accurate, it significantly outperformed the state-of-the-art 3D-2D registration method in terms of robustness measured by capture range and success rate.
Inversion strategies for visco-acoustic waveform inversion
NASA Astrophysics Data System (ADS)
Kamei, R.; Pratt, R. G.
2013-08-01
Visco-acoustic waveform inversion can potentially yield quantitative images of the distribution of both velocity and the attenuation parameters from seismic data. Intrinsic P-wave attenuation has been of particular interest, but has also proven challenging. Frequency-domain inversion allows attenuation and velocity relations to be easily incorporated, and allows a natural multiscale approach. The Laplace-Fourier approach extends this to allow the natural damping of waveforms to enhance early arrivals. Nevertheless, simultaneous inversion of velocity and attenuation leads to significant `cross-talk' between the resulting images, reflecting a lack of parameter resolution and indicating the need for pre-conditioning and regularization of the inverse problem. We analyse the cross-talk issue by partitioning the inversion parameters into two classes; the velocity parameter class, and the attenuation parameter class. Both parameters are defined at a reference frequency, and a dispersion relation is assumed that describes these parameters at any other frequency. We formulate the model gradients at a forward modelling frequency, and convert them to the reference frequency by employing the Jacobian of the coordinate change represented by the dispersion relation. We show that at a given modelling frequency, the Fréchet derivatives corresponding to these two parameter classes differ only by a 90° phase shift, meaning that the magnitudes of resulting model updates will be unscaled, and will not reflect the expected magnitudes in realistic (Q-1 ≪ 1) media. Due to the lack of scaling, cross-talk will be enhanced by poor subsurface illumination, by errors in kinematics, and by data noise. To solve these issues, we introduce an attenuation scaling term (the inverse of a penalty term) that is used to pre-condition the gradient by controlling the magnitudes of the updates to the attenuation parameters. Initial results from a suite of synthetic cross-hole tests using a three
Laboratory studies on N(2D) reactions of relevance to the chemistry of planetary atmospheres
NASA Astrophysics Data System (ADS)
Balucani, N.; Casavecchia, P.
collision conditions by means of the "crossed molecular beam" technique with mass spectrometric detection. Some examples of our experimental results will be illustrated, with particular attention to the reactions of N(2 D) with hydrocarbons (CH4 , C2 H2 and C2 H4 ) of relevance to the atmosphere of Titan, but also with other molecules of relevance to the atmospheres of Mars, Triton and Pluto.
Melton-Celsa, Angela R; O'Brien, Alison D; Feng, Peter C H
2015-11-01
Shiga toxin (Stx)-producing Escherichia coli (STEC) strains are food- and waterborne pathogens that are often transmitted via beef products or fresh produce. STEC strains cause both sporadic infections and outbreaks, which may result in hemorrhagic colitis and hemolytic uremic syndrome. STEC strains may elaborate Stx1, Stx2, and/or subtypes of those toxins. Epidemiological evidence indicates that STEC that produce subtypes Stx2a, Stx2c, and/or Stx2d are more often associated with serious illness. The Stx2d subtype becomes more toxic to Vero cells after incubation with intestinal mucus or elastase, a process named "activation." Stx2d is not generally found in the E. coli serotypes most commonly connected to STEC outbreaks. However, STEC strains that are stx2d positive can be isolated from foods, an occurrence that gives rise to the question of whether those food isolates are potential human pathogens. In this study, we examined 14 STEC strains from fresh produce that were stx2d positive and found that they all produced the mucus-activatable Stx2d and that a subset of the strains tested were virulent in streptomycin-treated mice.
Ward, Stephen; Heath, Victoria L.; Ismail, Tariq; Bicknell, Roy
2016-01-01
Current vascular-targeted therapies in colorectal cancer (CRC) have shown limited benefit. The lack of novel, specific treatment in CRC has been hampered by a dearth of specific endothelial markers. Microarray comparison of endothelial gene expression in patient-matched CRC and normal colon identified a panel of putative colorectal tumour endothelial markers. Of these the glutamate dependent NMDA receptor GRIN2D emerged as the most interesting target. GRIN2D expression was shown to be specific to colorectal cancer vessels by RTqPCR and IHC analysis. Its expression was additionally shown be predictive of improved survival in CRC. Targeted knockdown studies in vitro demonstrated a role for GRIN2D in endothelial function and angiogenesis. This effect was also shown in vivo as vaccination against the extracellular region of GRIN2D resulted in reduced vascularisation in the subcutaneous sponge angiogenesis assay. The utility of immunologically targeting GRIN2D in CRC was demonstrated by the vaccination approach inhibiting murine CRC tumour growth and vascularisation. GRIN2D represents a promising target for the future treatment of CRC. PMID:26943033
EFFECTS OF SMOKING ON D2/D3 STRIATAL RECEPTOR AVAILABILITY IN ALCOHOLICS AND SOCIAL DRINKERS
Albrecht, Daniel S.; Kareken, David A.; Yoder, Karmen K.
2013-01-01
Objective Studies have reported lower striatal D2/D3 receptor availability in both alcoholics and cigarette smokers relative to healthy controls. These substances are commonly co-abused, yet the relationship between comorbid alcohol/tobacco abuse and striatal D2/D3 receptor availability has not been examined. We sought to determine the degree to which dual abuse of alcohol and tobacco is associated with lower D2/D3 receptor availability. Method Eighty-one subjects (34 nontreatment-seeking alcoholic smokers [NTS-S], 21 social-drinking smokers [SD-S], and 26 social-drinking non-smokers [SD-NS]) received baseline [11C]raclopride scans. D2/D3 binding potential (BPND ≡ Bavail/KD) was estimated for ten anatomically defined striatal regions of interest (ROIs). Results Significant group effects were detected in bilateral pre-commissural dorsal putamen, bilateral pre-commissural dorsal caudate; and bilateral post-commissural dorsal putamen. Post-hoc testing revealed that, regardless of drinking status, smokers had lower D2/D3 receptor availability than non-smoking controls. Conclusions Chronic tobacco smokers have lower striatal D2/D3 receptor availability than non-smokers, independent of alcohol use. Additional studies are needed to identify the mechanisms by which chronic tobacco smoking is associated with striatal dopamine receptor availability. PMID:23649848
NASA Astrophysics Data System (ADS)
Singh, S. C.; Qin, Y.
2015-12-01
On active accretionary margins, the nature of incoming sediments defines the locking mechanism on the megathrust, and the development and evolution of the accretionary wedge. Drilling is the most direct method to characterise the nature of these sediments, but the drilling is very expensive, and provide information at only a few locations. In north Sumatra, an IODP drilling is programmed to take place in July-August 2016. We have performed seismic full waveform inversion of 12 km long offset seismic reflection data acquired by WesternGeco in 2006 over a 35 km zone near the subduction front in the 2004 earthquake rupture zone area that provide detailed quantitative information on the characteristics of the incoming sediments. We first downward continue the surface streamer data to the seafloor, which removes the effect of deep water (~5 km) and brings out the refraction arrivals as the first arrivals. We carry out travel time tomography, and then performed full waveform inversion of seismic refraction data followed by the full waveform inversion of reflection data providing detailed (10-20 m) velocity structure. The sediments in this area are 3-5 km thick where the P-wave velocity increases from 1.6 km/s near the seafloor to more than 4.5 km/s above the oceanic crust. The high velocity of sediments above the basement suggests that the sediments are highly compacted, strengthened the coupling near the subduction front, which might have been responsible for 2004 earthquake rupture propagation up to the subduction front, enhancing the tsunami. We also find several thin velocity layers within the sediments, which might be due to high pore-pressure fluid or free gas. These layers might be responsible for the formation of pseudo-decollement within the forearc sediments that acts as a conveyer belt between highly compacted subducting lower sediments and accreted sediments above. The presence of well intact sediments on the accretionary prism supports this interpretation
Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media
NASA Technical Reports Server (NTRS)
Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Liu, Feng (Inventor); Lax, Melvin (Inventor); Das, Bidyut B. (Inventor)
1999-01-01
A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: ##EQU1## wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise,
Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media
NASA Technical Reports Server (NTRS)
Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Gayen, Swapan K. (Inventor)
2000-01-01
A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise,
Stress inversion assumptions review
NASA Astrophysics Data System (ADS)
Lejri, Mostfa; Maerten, Frantz; Maerten, Laurent; Joonnenkindt, Jean Pierre; Soliva, Roger
2014-05-01
Wallace (1951) and Bott (1959) were the first to introduce the idea that the slip on each fault surface has the same direction and sense as the maximum shear stress resolved on that surface. This hypothesis are based on the assumptions that (i) faults are planar, (ii) blocks are rigid, (iii) neither stress perturbations nor block rotations along fault surfaces occur and (iv), the applied stress state is uniform. However, this simplified hypothesis is questionable since complex fault geometries, heterogeneous fault slip directions, evidences of stress perturbations in microstructures and block rotations along fault surfaces were reported in the literature. Earlier numerical geomechanical models confirmed that the striation lines (slip vectors) are not necessarily parallel to the maximum shear stress vector but is consistent with local stress perturbations. This leads us to ask as to what extent the Wallace and Bott simplifications are reliable as a basis hypothesis for stress inversion. In this presentation, a geomechanical multi-parametric study using 3D boundary element method (BEM), covering (i) fault geometries such as intersected faults or corrugated fault surfaces, (ii) the full range of Andersonian state of stress, (iii) fault friction, (iv) half space effect and (v), rock properties, is performed in order to understand the effect of each parameter on the angular misfit between geomechanical slip vectors and the resolved shear stresses. It is shown that significant angular misfits can be found under specific configurations and therefore we conclude that stress inversions based on the Wallace-Bott hypothesis might sometime give results that should be interpreted with care. Major observations are that (i) applying optimum tectonic stress conditions on complex fault geometries can increase the angular misfit, (ii) elastic material properties, combined to half-space effect, can enhance this effect, and (iii) an increase of the sliding friction leads to a
Laterally constrained inversion for CSAMT data interpretation
NASA Astrophysics Data System (ADS)
Wang, Ruo; Yin, Changchun; Wang, Miaoyue; Di, Qingyun
2015-10-01
Laterally constrained inversion (LCI) has been successfully applied to the inversion of dc resistivity, TEM and airborne EM data. However, it hasn't been yet applied to the interpretation of controlled-source audio-frequency magnetotelluric (CSAMT) data. In this paper, we apply the LCI method for CSAMT data inversion by preconditioning the Jacobian matrix. We apply a weighting matrix to Jacobian to balance the sensitivity of model parameters, so that the resolution with respect to different model parameters becomes more uniform. Numerical experiments confirm that this can improve the convergence of the inversion. We first invert a synthetic dataset with and without noise to investigate the effect of LCI applications to CSAMT data, for the noise free data, the results show that the LCI method can recover the true model better compared to the traditional single-station inversion; and for the noisy data, the true model is recovered even with a noise level of 8%, indicating that LCI inversions are to some extent noise insensitive. Then, we re-invert two CSAMT datasets collected respectively in a watershed and a coal mine area in Northern China and compare our results with those from previous inversions. The comparison with the previous inversion in a coal mine shows that LCI method delivers smoother layer interfaces that well correlate to seismic data, while comparison with a global searching algorithm of simulated annealing (SA) in a watershed shows that though both methods deliver very similar good results, however, LCI algorithm presented in this paper runs much faster. The inversion results for the coal mine CSAMT survey show that a conductive water-bearing zone that was not revealed by the previous inversions has been identified by the LCI. This further demonstrates that the method presented in this paper works for CSAMT data inversion.
Comparison of 1D and 2D CSR Models with Application to the FERMI@ELETTRA Bunch Compressors
Bassi, G.; Ellison, J.A.; Heinemann, K.
2011-03-28
We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces [1]. The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. As an application, we present numerical results for the Fermi{at}Elettra first bunch compressor with the configuration described in [1].
Applications of inverse pattern projection
NASA Astrophysics Data System (ADS)
Li, Wansong; Bothe, Thorsten; Kalms, Michael K.; von Kopylow, Christoph; Jueptner, Werner P. O.
2003-05-01
Fast and robust 3D quality control as well as fast deformation measurement is of particular importance for industrial inspection. Additionally a direct response about measured properties is desired. Therefore, robust optical techniques are needed which use as few images as possible for measurement and visualize results in an efficient way. One promising technique for this aim is the inverse pattern projection which has the following advantages: The technique codes the information of a preceding measurement into the projected inverse pattern. Thus, it is possible to do differential measurements using only one camera frame for each state. Additionally, the results are optimized straight fringes for sampling which are independent of the object curvature. The hardware needs are low as just a programmable projector and a standard camera are necessary. The basic idea of inverse pattern projection, necessary algorithms and found optimizations are demonstrated, roughly. Evaluation techniques were found to preserve a high quality phase measurement under imperfect conditions. The different application fields can be sorted out by the type of pattern used for inverse projection. We select two main topics for presentation. One is the incremental (one image per state) deformation measurement which is a promising technique for high speed deformation measurements. A video series of a wavering flag with projected inverse pattern was evaluated to show the complete deformation series. The other application is the optical feature marking (augmented reality) that allows to map any measured result directly onto the object under investigation. Any properties can be visualized directly on the object"s surface which makes inspections easier than with use of a separated indicating device. The general ability to straighten any kind of information on 3D surfaces is shown while preserving an exact mapping of camera image and object parts. In many cases this supersedes an additional monitor to
Alloyed 2D Metal-Semiconductor Atomic Layer Junctions.
Kim, Ah Ra; Kim, Yonghun; Nam, Jaewook; Chung, Hee-Suk; Kim, Dong Jae; Kwon, Jung-Dae; Park, Sang Won; Park, Jucheol; Choi, Sun Young; Lee, Byoung Hun; Park, Ji Hyeon; Lee, Kyu Hwan; Kim, Dong-Ho; Choi, Sung Mook; Ajayan, Pulickel M; Hahm, Myung Gwan; Cho, Byungjin
2016-03-01
Heterostructures of compositionally and electronically variant two-dimensional (2D) atomic layers are viable building blocks for ultrathin optoelectronic devices. We show that the composition of interfacial transition region between semiconducting WSe2 atomic layer channels and metallic NbSe2 contact layers can be engineered through interfacial doping with Nb atoms. WxNb1-xSe2 interfacial regions considerably lower the potential barrier height of the junction, significantly improving the performance of the corresponding WSe2-based field-effect transistor devices. The creation of such alloyed 2D junctions between dissimilar atomic layer domains could be the most important factor in controlling the electronic properties of 2D junctions and the design and fabrication of 2D atomic layer devices.
2D hexagonal quaternion Fourier transform in color image processing
NASA Astrophysics Data System (ADS)
Grigoryan, Artyom M.; Agaian, Sos S.
2016-05-01
In this paper, we present a novel concept of the quaternion discrete Fourier transform on the two-dimensional hexagonal lattice, which we call the two-dimensional hexagonal quaternion discrete Fourier transform (2-D HQDFT). The concept of the right-side 2D HQDFT is described and the left-side 2-D HQDFT is similarly considered. To calculate the transform, the image on the hexagonal lattice is described in the tensor representation when the image is presented by a set of 1-D signals, or splitting-signals which can be separately processed in the frequency domain. The 2-D HQDFT can be calculated by a set of 1-D quaternion discrete Fourier transforms (QDFT) of the splitting-signals.
Technical Review of the UNET2D Hydraulic Model
Perkins, William A.; Richmond, Marshall C.
2009-05-18
The Kansas City District of the US Army Corps of Engineers is engaged in a broad range of river management projects that require knowledge of spatially-varied hydraulic conditions such as velocities and water surface elevations. This information is needed to design new structures, improve existing operations, and assess aquatic habitat. Two-dimensional (2D) depth-averaged numerical hydraulic models are a common tool that can be used to provide velocity and depth information. Kansas City District is currently using a specific 2D model, UNET2D, that has been developed to meet the needs of their river engineering applications. This report documents a tech- nical review of UNET2D.
Alloyed 2D Metal-Semiconductor Atomic Layer Junctions.
Kim, Ah Ra; Kim, Yonghun; Nam, Jaewook; Chung, Hee-Suk; Kim, Dong Jae; Kwon, Jung-Dae; Park, Sang Won; Park, Jucheol; Choi, Sun Young; Lee, Byoung Hun; Park, Ji Hyeon; Lee, Kyu Hwan; Kim, Dong-Ho; Choi, Sung Mook; Ajayan, Pulickel M; Hahm, Myung Gwan; Cho, Byungjin
2016-03-01
Heterostructures of compositionally and electronically variant two-dimensional (2D) atomic layers are viable building blocks for ultrathin optoelectronic devices. We show that the composition of interfacial transition region between semiconducting WSe2 atomic layer channels and metallic NbSe2 contact layers can be engineered through interfacial doping with Nb atoms. WxNb1-xSe2 interfacial regions considerably lower the potential barrier height of the junction, significantly improving the performance of the corresponding WSe2-based field-effect transistor devices. The creation of such alloyed 2D junctions between dissimilar atomic layer domains could be the most important factor in controlling the electronic properties of 2D junctions and the design and fabrication of 2D atomic layer devices. PMID:26839956