Defect formation and coarsening in hexagonal 2D curved crystals.
García, Nicolás A; Pezzutti, Aldo D; Register, Richard A; Vega, Daniel A; Gómez, Leopoldo R
2015-02-01
In this work we study the processes of defect formation and coarsening of two-dimensional (2D) curved crystal structures. These processes are found to strongly deviate from their counterparts in flat systems. In curved backgrounds the process of defect formation is deeply affected by the curvature, and at the onset of a phase transition the early density of defects becomes highly inhomogeneous. We observe that even a single growing crystal can produce varying densities of defects depending on its initial position and local orientation with regard to the substrate. This process is completely different from flat space, where grain boundaries are formed due to the impingement of different propagating crystals. Quenching the liquid into the crystal phase leads to the formation of a curved polycrystalline structure, characterized by complex arrays of defects. During annealing, mechanisms of geodesic curvature-driven grain boundary motion and defect annihilation lead to increasing crystalline order. Linear arrays of defects diffuse to regions of high curvature, where they are absorbed by disclinations. At the early stage of coarsening the density of dislocations is insensitive to the geometry while the population of isolated disclinations is deeply affected by curvature. The regions with high curvature act as traps for the diffusion of different structures of defects, including disclinations and domain walls.
Improved beamforming using curved sparse 2D arrays in ultrasound.
Kirkebø, Jan Egil; Austeng, Andreas
2007-05-01
In this work we have investigated the effect of curving phase-steered sparse periodic two-dimensional arrays in one direction, and relate this effect to the geometry of the arrays. We have shown that curving is equivalent to removing some of the element periodicity, thus adding some "randomness" to the layout. Compared to flat phase-steered periodically sparse two-dimensional arrays, curving offers an even greater suppression of grating lobes located at directions along the curvature. The class of arrays yielding improved performance due to this suppression of grating lobes has been characterized. The point spread functions of some previously proposed array layouts, shown to be promising for ultrasonic imaging, have been simulated. The arrays have been simulated with various number of elements as well as various focal points, with array and field parameters typical to those in volumetric cardiac imaging. On a 48 x 48 element grid with a transducer center frequency of 3 MHz and the target at 40 mm, reductions in the peak sidelobe level of up to 12dB were recorded for some critical steering directions, without significant differences in the beamwidth. The integrated sidelobe ratio was also examined, showing an almost equivalent performance as the flat array. This study shows that, without adding any complexity to the system, the overall image quality of a volumetric imaging system can be improved significantly by curving the array in one direction. PMID:17313966
Measuring (13)C-(2)D dipolar couplings with a universal REDOR dephasing curve
Gullion
2000-09-01
A (13)C-observe REDOR experiment is described which allows (13)C-(2)D dipolar couplings to be obtained by a universal dipolar dephasing curve. Previous (13)C-observe REDOR experiments on (13)C-(2)D spin pairs generally relied on numerical simulations to obtain the dipolar coupling. The REDOR experiment described in this article is based on a deuterium composite pulse, and the data analysis eliminates the need for numerical simulations and is the same as the traditional REDOR analysis performed on pairs of spin-12 nuclei. Copyright 2000 Academic Press. PMID:10968975
VectorLens: Angular Selection of Curves within 2D Dense Visualizations.
Dumas, Maxime; McGuffin, Michael J; Chassé, Patrick
2015-03-01
We investigate the selection of curves within a 2D visualization by specifying their angle or slope. Such angular selection has applications in parallel coordinates, time series visualizations, spatio-temporal movement data, etc. Our interaction technique specifies a region of interest in the visualization (with a position and diameter), a direction, and an angular tolerance, all with a single drag. We experimentally compared this angular selection technique with other techniques for selecting curves, and found that angular selection resulted in a higher number of trials that were successful on the first attempt and fewer incorrectly selected curves, and was also subjectively preferred by participants. We then present the design of a popup lens widget, called the VectorLens, that allows for easy angular selection and also allows the user to perform additional filtering operations based on type of curve. Multiple VectorLens widgets can also be instantiated to combine the results of their filtering operations with boolean operators.
Image restoration using 2D autoregressive texture model and structure curve construction
NASA Astrophysics Data System (ADS)
Voronin, V. V.; Marchuk, V. I.; Petrosov, S. P.; Svirin, I.; Agaian, S.; Egiazarian, K.
2015-05-01
In this paper an image inpainting approach based on the construction of a composite curve for the restoration of the edges of objects in an image using the concepts of parametric and geometric continuity is presented. It is shown that this approach allows to restore the curved edges and provide more flexibility for curve design in damaged image by interpolating the boundaries of objects by cubic splines. After edge restoration stage, a texture restoration using 2D autoregressive texture model is carried out. The image intensity is locally modeled by a first spatial autoregressive model with support in a strongly causal prediction region on the plane. Model parameters are estimated by Yule-Walker method. Several examples considered in this paper show the effectiveness of the proposed approach for large objects removal as well as recovery of small regions on several test images.
NASA Astrophysics Data System (ADS)
Li, Yushuang; Liu, Qian; Zheng, Xiaoqi
2016-08-01
A highly compact and simple 2D graphical representation of DNA sequences, named DUC-Curve, is constructed through mapping four nucleotides to a unit circle with a cyclic order. DUC-Curve could directly detect nucleotide, di-nucleotide compositions and microsatellite structure from DNA sequences. Moreover, it also could be used for DNA sequence alignment. Taking geometric center vectors of DUC-Curves as sequence descriptor, we perform similarity analysis on the first exons of β-globin genes of 11 species, oncogene TP53 of 27 species and twenty-four Influenza A viruses, respectively. The obtained reasonable results illustrate that the proposed method is very effective in sequence comparison problems, and will at least play a complementary role in classification and clustering problems.
Robust mean traveltime curves: a powerful tool for analysis in 2D transmission tomographic surveys
NASA Astrophysics Data System (ADS)
Fernandez Martinez, J.; Pedruelo Gonzalez, L.; Rector, J.
2008-12-01
Acoustic tomography methods belong to the class of non destructive inspection techniques and are widely used in engineering applications. One of the main issues for these methods is the direct arrivals, which can be noisy or affected by scattering or other propagation effects. Mean traveltime curves (mean and standard deviation) have been introduced by Fernández Martínez et al (2006), and describe the variation of the main statistical parameters of the traveltime distribution for the different gathering subsets as a function of the gather index. These curves constitute a simple methodology (Fernández Martínez et al., 2008) to analyze before inversion the traveltime quality in 2D acoustic transmission tomography experiments conducted in relatively homogeneous blocks. This analysis can help to discriminate the contribution of picking errors from that of geological heterogeneities. In this contribution we present the so-called robust mean traveltime curves, which refer to the variation of the different p-percentiles and related measures of dispersion (inter-quartile range and minimum absolute deviation) for the above mentioned gathering subsets. Together with the mean curve, the median and upper-quartile traveltime curves are very resistant to the presence of outliers, and thus, are preferred to infer a background velocity model, which is valid at experiment scale and honors the experimental traveltime distribution. This methodology is valid for 2D zonal isotropic or elliptical anisotropic media, explored via any arbitrary acquisition geometry. We show the application to a well-known granitic medium (Febex Project, Nagra, Switzerland). Fernández Martínez et al. 2006. Mathematical Geology:38-3.343-374 Fernández Martínez et al.2008. Computer and Geosciences:34-3,213-225, 2008.
3D combinational curves for accuracy and performance analysis of positive biometrics identification
NASA Astrophysics Data System (ADS)
Du, Yingzi; Chang, Chein-I.
2008-06-01
The receiver operating characteristic (ROC) curve has been widely used as an evaluation criterion to measure the accuracy of biometrics system. Unfortunately, such an ROC curve provides no indication of the optimum threshold and cost function. In this paper, two kinds of 3D combinational curves are proposed: the 3D combinational accuracy curve and the 3D combinational performance curve. The 3D combinational accuracy curve gives a balanced view of the relationships among FAR (false alarm rate), FRR (false rejection rate), threshold t, and Cost. Six 2D curves can be derived from the 3D combinational accuracy curve: the conventional 2D ROC curve, 2D curve of (FRR, t), 2D curve of (FAR, t), 2D curve of (FRR, Cost), 2D curve of (FAR, Cost), and 2D curve of ( t, Cost). The 3D combinational performance curve can be derived from the 3D combinational accuracy curve which can give a balanced view among Security, Convenience, threshold t, and Cost. The advantages of using the proposed 3D combinational curves are demonstrated by iris recognition systems where the experimental results show that the proposed 3D combinational curves can provide more comprehensive information of the system accuracy and performance.
Phase Behavior of 2D Charged Hydrophobic Colloids in Flat and Curved Space
NASA Astrophysics Data System (ADS)
Kelleher, Colm; Guerra, Rodrigo; Chaikin, Paul
Charged hydrophobic colloids, when dispersed in oil with a relatively high dielectric constant, can become highly charged. In the presence of an interface with a conducting aqueous phase, particles bind strongly to the interface via image-charge attraction. At sufficiently high density, these charged interfacial particles self-organize into a 2D repulsive (Wigner) crystalline solid phase, while at lower densities, the particles form a 2D fluid. By observing samples prepared at different densities, we can probe various points in the phase diagram of this soft 2D material, and compare our results with applicable theory and simulations. In this talk, we present two sets of experiments we have performed on this system: first, we show how we can use gravity as an external force to create a controlled density gradient, and thereby directly measure the equation of state and other quantities of interest. Second, we discuss how, by observing particles which are bound to the surface of spherical droplets, we can explore how the presence of finite background curvature affects the phase behavior of the system.
NEXT Performance Curve Analysis and Validation
NASA Technical Reports Server (NTRS)
Saripalli, Pratik; Cardiff, Eric; Englander, Jacob
2016-01-01
Performance curves of the NEXT thruster are highly important in determining the thruster's ability in performing towards mission-specific goals. New performance curves are proposed and examined here. The Evolutionary Mission Trajectory Generator (EMTG) is used to verify variations in mission solutions based on both available thruster curves and the new curves generated. Furthermore, variations in BOL and EOL curves are also examined. Mission design results shown here validate the use of EMTG and the new performance curves.
Dynamical Models of SAURON and CALIFA Galaxies: 1D and 2D Rotational Curves
NASA Astrophysics Data System (ADS)
Kalinova, Veselina; van de Ven, G.; Lyubenova, M.; Falcon-Barroso, J.; van den Bosch, R.
2013-01-01
The mass of a galaxy is the most important parameter to understand its structure and evolution. The total mass we can infer by constructing dynamical models that fit the motion of the stars and gas in the galaxy. The dark matter content then follows after subtracting the luminous matter inferred from colors and/or spectra. Here, we present the mass distribution of a sample of 18 late-type spiral (Sb-Sd) galaxies, using two-dimensional stellar kinematics obtained with the integral-field spectrograph SAURON. The observed second order velocity moments of these galaxies are fitted with solutions of the Axisymmetric Jeans equations and give us an accurate estimation of the mass-to-light ratio profiles and rotational curves. The rotation curves of the galaxies are obtained by the Asymmetric Drift Correction (ADC) and Multi-Gaussian Expansion (MGE) methods, corresponding to one- and two-dimensional mass distribution. Their comparison shows that the mass distribution based on the 2D stellar kinematics is much more reliable than 1D one. SAURON integral field of view looks at the inner parts of the galaxies in contrast with CALIFA survey. CALIFA survey provides PMAS/PPAK integral-field spectroscopic data of ~ 600 nearby galaxies as part of the Calar Alto Legacy Integral Field Area. We show the first CALIFA dynamical models of different morphological type of galaxies, giving the clue about the mass distribution of galaxies through the whole Hubble sequence and their evolution from the blue cloud to the red sequence.
Artifacts in time-resolved NUS: A case study of NOE build-up curves from 2D NOESY.
Dass, Rupashree; Kasprzak, Paweł; Koźmiński, Wiktor; Kazimierczuk, Krzysztof
2016-04-01
Multidimensional NMR spectroscopy requires time-consuming sampling of indirect dimensions and so is usually used to study stable samples. However, dynamically changing compounds or their mixtures commonly occur in problems of natural science. Monitoring them requires the use multidimensional NMR in a time-resolved manner - in other words, a series of quick spectra must be acquired at different points in time. Among the many solutions that have been proposed to achieve this goal, time-resolved non-uniform sampling (TR-NUS) is one of the simplest. In a TR-NUS experiment, the signal is sampled using a shuffled random schedule and then divided into overlapping subsets. These subsets are then processed using one of the NUS reconstruction methods, for example compressed sensing (CS). The resulting stack of spectra forms a temporal "pseudo-dimension" that shows the changes caused by the process occurring in the sample. CS enables the use of small subsets of data, which minimizes the averaging of the effects studied. Yet, even within these limited timeframes, the sample undergoes certain changes. In this paper we discuss the effect of varying signal amplitude in a TR-NUS experiment. Our theoretical calculations show that the variations within the subsets lead to t1-noise, which is dependent on the rate of change of the signal amplitude. We verify these predictions experimentally. As a model case we choose a novel 2D TR-NOESY experiment in which mixing time is varied in parallel with shuffled NUS in the indirect dimension. The experiment, performed on a sample of strychnine, provides a near-continuous NOE build-up curve, whose shape closely reflects the t1-noise level. 2D TR-NOESY reduces the measurement time compared to the conventional approach and makes it possible to verify the theoretical predictions about signal variations during TR-NUS. PMID:26896866
Artifacts in time-resolved NUS: A case study of NOE build-up curves from 2D NOESY
NASA Astrophysics Data System (ADS)
Dass, Rupashree; Kasprzak, Paweł; Koźmiński, Wiktor; Kazimierczuk, Krzysztof
2016-04-01
Multidimensional NMR spectroscopy requires time-consuming sampling of indirect dimensions and so is usually used to study stable samples. However, dynamically changing compounds or their mixtures commonly occur in problems of natural science. Monitoring them requires the use multidimensional NMR in a time-resolved manner - in other words, a series of quick spectra must be acquired at different points in time. Among the many solutions that have been proposed to achieve this goal, time-resolved non-uniform sampling (TR-NUS) is one of the simplest. In a TR-NUS experiment, the signal is sampled using a shuffled random schedule and then divided into overlapping subsets. These subsets are then processed using one of the NUS reconstruction methods, for example compressed sensing (CS). The resulting stack of spectra forms a temporal "pseudo-dimension" that shows the changes caused by the process occurring in the sample. CS enables the use of small subsets of data, which minimizes the averaging of the effects studied. Yet, even within these limited timeframes, the sample undergoes certain changes. In this paper we discuss the effect of varying signal amplitude in a TR-NUS experiment. Our theoretical calculations show that the variations within the subsets lead to t1 -noise, which is dependent on the rate of change of the signal amplitude. We verify these predictions experimentally. As a model case we choose a novel 2D TR-NOESY experiment in which mixing time is varied in parallel with shuffled NUS in the indirect dimension. The experiment, performed on a sample of strychnine, provides a near-continuous NOE build-up curve, whose shape closely reflects the t1 -noise level. 2D TR-NOESY reduces the measurement time compared to the conventional approach and makes it possible to verify the theoretical predictions about signal variations during TR-NUS.
Malenovská, Hana
2016-02-01
Only very few comparative studies have been performed that evaluate general trends of virus growth under 3D in comparison with 2D cell culture conditions. The aim of this study was to investigate differences when four animal viruses are cultured in 2D and 3D. Suid herpesvirus 1 (SuHV-1), Vesicular stomatitis virus (VSIV), Bovine adenovirus (BAdV) and Bovine parainfluenza 3 virus (BPIV-3) were cultivated in 3D rotating wall vessels (RWVs) and conventional 2D cultures. The production of virus particles, the portion of infectious particles, and the infectious growth curves were compared. For all viruses, the production of virus particles (related to cell density), including the non-infectious ones, was lower in 3D than in 2D culture. The production of only infectious particles was significantly lower in BAdV and BPIV-3 in 3D cultures in relation to cell density. The two cultivation approaches resulted in significantly different virus particle-to-TCID50 ratios in three of the four viruses: lower in SuHV-1 and BPIV-3 and higher in BAdV in 3D culture. The infectious virus growth rates were not significantly different in all viruses. Although 3D RWV culture resulted in lower production of virus particles compared to 2D systems, the portion of infectious particles was higher for some viruses.
Experimental study on nonmonotonicity of Capillary Desaturation Curves in a 2-D pore network
NASA Astrophysics Data System (ADS)
Rodríguez de Castro, Antonio; Shokri, Nima; Karadimitriou, Nikolaos; Oostrom, Mart; Joekar-Niasar, Vahid
2015-10-01
Immiscible displacement in porous media is important in many applications such as soil remediation and enhanced oil recovery. When gravitational forces are negligible, two-phase immiscible displacement at the pore level is controlled by capillary and viscous forces whose relative importance is quantified through the dimensionless capillary number Ca and the viscosity ratio M between liquid phases. Depending on the values of Ca and M, capillary fingering, viscous fingering, or stable displacement may be observed resulting in a variety of patterns affecting the phase entrapment. The Capillary Desaturation Curve (CDC), which represents the relationship between the residual oil saturation and Ca, is an important relation to describe the phase entrapment at a given Ca. In the present study, we investigated the CDC as influenced by the viscosity ratio. To do so, we have conducted a comprehensive series of experiments using a high-resolution microscope and state-of-art micromodels to investigate the dynamics and patterns of phase entrapment at different Ca and M. By postprocessing of the experimental high-resolution images, we calculated the CDC and quantified the effects of the Ca and M on the phase entrapment and number of blobs trapped in the micromodel and their size distributions during immiscible two-phase flow. Our results show that CDCs are not necessarily monotonic for all M, and the physical mechanisms causing this nonmonotonic behavior are discussed.
Experimental study on nonmonotonicity of capillary desaturation curves in a 2-D pore-network
Rodriquez de Castro, Antonio; Shokri, Nima; Karadimitriou, Nikolaos; Oostrom, Martinus; Joekar-Niasar, Vahid
2015-10-28
Immiscible displacement in a porous medium is important in many applications such as soil remediation and enhanced oil recovery. When gravitational forces are negligible, two-phase immiscible displacement at the pore level is controlled by capillary and viscous forces whose relative importance is quantified through the dimensionless capillary number Ca and the viscosity ratio M between liquid phases. Depending on the values of Ca and M, capillary fingering, viscous fingering, or stable displacement may be observed resulting in a variety of patterns affecting the phase entrapment. The Capillary Desaturation Curve (CDC), which represents the relationship between the residual oils saturation and Ca, is an important relation to describe the phase entrapment at a given Ca. In the present study, we investigate the CDC as influenced by the viscosity ratio. A comprehensive series of experiments using a high-resolution microscope and state-of-the-art micromodels were conducted. The CDCs were calculated and the effects of Ca and M on phase entrapments were quantified. The results show that CDCs are not necessarily monotonic for all M.
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.
Chuang, Hsun-Jen; Chamlagain, Bhim; Koehler, Michael; Perera, Meeghage Madusanka; Yan, Jiaqiang; Mandrus, David; Tománek, David; Zhou, Zhixian
2016-03-01
We report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ∼0.3 kΩ μm, high on/off ratios up to >10(9), and high drive currents exceeding 320 μA μm(-1). These favorable characteristics are combined with a two-terminal field-effect hole mobility μFE ≈ 2 × 10(2) cm(2) V(-1) s(-1) at room temperature, which increases to >2 × 10(3) cm(2) V(-1) s(-1) at cryogenic temperatures. We observe a similar performance also in MoS2 and MoSe2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in postsilicon electronics.
High performance CCD camera system for digitalisation of 2D DIGE gels.
Strijkstra, Annemieke; Trautwein, Kathleen; Roesler, Stefan; Feenders, Christoph; Danzer, Daniel; Riemenschneider, Udo; Blasius, Bernd; Rabus, Ralf
2016-07-01
An essential step in 2D DIGE-based analysis of differential proteome profiles is the accurate and sensitive digitalisation of 2D DIGE gels. The performance progress of commercially available charge-coupled device (CCD) camera-based systems combined with light emitting diodes (LED) opens up a new possibility for this type of digitalisation. Here, we assessed the performance of a CCD camera system (Intas Advanced 2D Imager) as alternative to a traditionally employed, high-end laser scanner system (Typhoon 9400) for digitalisation of differential protein profiles from three different environmental bacteria. Overall, the performance of the CCD camera system was comparable to the laser scanner, as evident from very similar protein abundance changes (irrespective of spot position and volume), as well as from linear range and limit of detection.
High performance CCD camera system for digitalisation of 2D DIGE gels.
Strijkstra, Annemieke; Trautwein, Kathleen; Roesler, Stefan; Feenders, Christoph; Danzer, Daniel; Riemenschneider, Udo; Blasius, Bernd; Rabus, Ralf
2016-07-01
An essential step in 2D DIGE-based analysis of differential proteome profiles is the accurate and sensitive digitalisation of 2D DIGE gels. The performance progress of commercially available charge-coupled device (CCD) camera-based systems combined with light emitting diodes (LED) opens up a new possibility for this type of digitalisation. Here, we assessed the performance of a CCD camera system (Intas Advanced 2D Imager) as alternative to a traditionally employed, high-end laser scanner system (Typhoon 9400) for digitalisation of differential protein profiles from three different environmental bacteria. Overall, the performance of the CCD camera system was comparable to the laser scanner, as evident from very similar protein abundance changes (irrespective of spot position and volume), as well as from linear range and limit of detection. PMID:27252121
Effects of Cognitive Styles on 2D Drafting and Design Performance in Digital Media
ERIC Educational Resources Information Center
Pektas, Sule Tasli
2010-01-01
This paper investigates the interactions between design students' cognitive styles, as measured by Riding's Cognitive Styles Analysis, and performance in 2D drafting and design tasks in digital media. An empirical research revealed that Imager students outperformed Verbalisers in both drafting and creativity scores. Wholist-Analytic cognitive…
NASA Astrophysics Data System (ADS)
Cockmartin, Lesley; Marshall, Nicholas W.; Van Ongeval, Chantal; Aerts, Gwen; Stalmans, Davina; Zanca, Federica; Shaheen, Eman; De Keyzer, Frederik; Dance, David R.; Young, Kenneth C.; Bosmans, Hilde
2015-05-01
This paper introduces a hybrid method for performing detection studies in projection image based modalities, based on image acquisitions of target objects and patients. The method was used to compare 2D mammography and digital breast tomosynthesis (DBT) in terms of the detection performance of spherical densities and microcalcifications. The method starts with the acquisition of spheres of different glandular equivalent densities and microcalcifications of different sizes immersed in a homogeneous breast tissue simulating medium. These target objects are then segmented and the subsequent templates are fused in projection images of patients and processed or reconstructed. This results in hybrid images with true mammographic anatomy and clinically relevant target objects, ready for use in observer studies. The detection study of spherical densities used 108 normal and 178 hybrid 2D and DBT images; 156 normal and 321 hybrid images were used for the microcalcifications. Seven observers scored the presence/absence of the spheres/microcalcifications in a square region via a 5-point confidence rating scale. Detection performance in 2D and DBT was compared via ROC analysis with sub-analyses for the density of the spheres, microcalcification size, breast thickness and z-position. The study was performed on a Siemens Inspiration tomosynthesis system using patient acquisitions with an average age of 58 years and an average breast thickness of 53 mm providing mean glandular doses of 1.06 mGy (2D) and 2.39 mGy (DBT). Study results showed that breast tomosynthesis (AUC = 0.973) outperformed 2D (AUC = 0.831) for the detection of spheres (p < 0.0001) and this applied for all spherical densities and breast thicknesses. By way of contrast, DBT was worse than 2D for microcalcification detection (AUC2D = 0.974, AUCDBT = 0.838, p < 0.0001), with significant differences found for all sizes (150-354 µm), for breast thicknesses above 40 mm and for heights
Diewok, Josef; Ayora-Cañada, María Jose; Lendl, Bernhard
2002-10-01
Multivariate curve resolution (MCR) and 2D correlation spectroscopy (2D-CoS), including sample-sample correlation, have been applied to the analysis of evolving midinfrared spectroscopic data sets obtained from titrations of organic acids in aqueous solution. In these data sets, well-defined species with significant differences in their spectra are responsible for the spectral variation observed. The two fundamentally different chemometric techniques have been evaluated and discussed on the basis of experimental and supportive simulated data sets. MCR gives information that can be directly related to the chemical species that is of importance from a practical point of view, whereas 2D-CoS results normally require more interpretation. The obtained conclusions are regarded valid for similar evolving data, which are increasingly being encountered in analytical chemistry when multivariate detectors are used to follow dynamic processes, including separations as well as chemical reactions, among others.
IGUANA: a high-performance 2D and 3D visualisation system
NASA Astrophysics Data System (ADS)
Alverson, G.; Eulisse, G.; Muzaffar, S.; Osborne, I.; Taylor, L.; Tuura, L. A.
2004-11-01
The IGUANA project has developed visualisation tools for multiple high-energy experiments. At the core of IGUANA is a generic, high-performance visualisation system based on OpenInventor and OpenGL. This paper describes the back-end and a feature-rich 3D visualisation system built on it, as well as a new 2D visualisation system that can automatically generate 2D views from 3D data, for example to produce R/Z or X/Y detector displays from existing 3D display with little effort. IGUANA has collaborated with the open-source gl2ps project to create a high-quality vector postscript output that can produce true vector graphics output from any OpenGL 2D or 3D display, complete with surface shading and culling of invisible surfaces. We describe how it works. We also describe how one can measure the memory and performance costs of various OpenInventor constructs and how to test scene graphs. We present good patterns to follow and bad patterns to avoid. We have added more advanced tools such as per-object clipping, slicing, lighting or animation, as well as multiple linked views with OpenInventor, and describe them in this paper. We give details on how to edit object appearance efficiently and easily, and even dynamically as a function of object properties, with instant visual feedback to the user.
Duan, Jianxin; Dixon, Steven L; Lowrie, Jeffrey F; Sherman, Woody
2010-09-01
Virtual screening is a widely used strategy in modern drug discovery and 2D fingerprint similarity is an important tool that has been successfully applied to retrieve active compounds from large datasets. However, it is not always straightforward to select an appropriate fingerprint method and associated settings for a given problem. Here, we applied eight different fingerprint methods, as implemented in the new cheminformatics package Canvas, on a well-validated dataset covering five targets. The fingerprint methods include Linear, Dendritic, Radial, MACCS, MOLPRINT2D, Pairwise, Triplet, and Torsion. We find that most fingerprints have similar retrieval rates on average; however, each has special characteristics that distinguish its performance on different query molecules and ligand sets. For example, some fingerprints exhibit a significant ligand size dependency whereas others are more robust with respect to variations in the query or active compounds. In cases where little information is known about the active ligands, MOLPRINT2D fingerprints produce the highest average retrieval actives. When multiple queries are available, we find that a fingerprint averaged over all query molecules is generally superior to fingerprints derived from single queries. Finally, a complementarity metric is proposed to determine which fingerprint methods can be combined to improve screening results.
Grossberg, Stephen; Swaminathan, Gurumurthy
2004-05-01
A model of laminar visual cortical dynamics proposes how 3D boundary and surface representations arise from viewing slanted and curved 3D objects and 2D images. The 3D boundary representations emerge from non-classical receptive field interactions within intracortical and intercortical feedback circuits. Such non-classical interactions within cortical areas V1 and V2 contextually disambiguate classical receptive field responses to ambiguous visual cues using cells that are sensitive to colinear contours, angles, and disparity gradients. Remarkably, these cell types can all be explained as variants of a unified perceptual grouping circuit whose most familiar example is a 2D colinear bipole cell. Model simulations show how this circuit can develop cell selectivity to colinear contours and angles, how slanted surfaces can activate 3D boundary representations that are sensitive to angles and disparity gradients, how 3D filling-in occurs across slanted surfaces, how a 2D Necker cube image can be represented in 3D, and how bistable 3D Necker cube percepts occur. The model also explains data about slant aftereffects and 3D neon color spreading. It shows how chemical transmitters that habituate, or depress, in an activity-dependent way can help to control development and also to trigger bistable 3D percepts and slant aftereffects. Attention can influence which of these percepts is perceived by propagating selectively along object boundaries.
On the thrust performance of a 2D flapping foil in a forward flight condition
NASA Astrophysics Data System (ADS)
Dash, Sunil Manohar; Lua, Kim Boon; Lim, Tee Tai
2015-11-01
Past studies have shown that the thrust performance of a 2D airfoil undergoing simple harmonic motion in both pitch and heave in a forward flight condition is dependent on maximum effective angle of attack (αo) and Strouhal number (ST) . For a given αo, it is found that the thrust coefficient (CT) increases with ST until it reaches a peak value at the critical Strouhal number (STc) ; beyond which CT deteriorates considerably. In order to extend STc and therefore increase the max.CT, the airfoil must oscillate at a higher αo. Further, it is found that, regardless of αo thrust degeneration is accompanied by cessation of the induced effective angle of attack profile (α(t)) to exhibit simple harmonic function of time. As to why non simple harmonic function of α(t) is detrimental to thrust generation is not fully understood. In an attempt to better understand this phenomenon, both numerical simulations and comparative experiments are performed on a 2D flapping elliptic foil at Re of 5000. Our results show that the proximity of the leading edge vortex from the previous stroke to the oscillating foil plays a crucial role in the thrust generation. Detailed results will be discussed in the presentation.
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
Ankle moment generation and maximum-effort curved sprinting performance.
Luo, Geng; Stefanyshyn, Darren
2012-11-15
Turning at high speed along acute curves is crucial for athletic performance. One determinant of curved sprinting speed is the ground reaction force that can be created by the supporting limb; the moment generated at the ankle joint may influence such force generation. Body lean associated with curved sprints positions the ankle joints in extreme in-/eversion, and may hinder the ankle moment generation. To examine the influence of ankle moment generation on curved sprinting performance, 17 male subjects performed maximum-effort curved sprints in footwear with and without a wedge. The wedged footwear was constructed with the intention to align the ankle joints closer to their neutral frontal-plane configuration during counter-clockwise curved sprints so greater joint moments might be generated. We found, with the wedged footwear, the average eversion angle of the inside leg ankle was reduced, and the plantarflexion moment generation increased significantly. Meanwhile, the knee extension moment remained unchanged. With the wedged footwear, stance-average centripetal ground reaction force increased significantly while no difference in the vertical ground reaction force was detected. The subjects created a greater centripetal ground reaction impulse in the wedged footwear despite a shortened stance phase when compared to the control. Stance-average curved sprinting speed improved by 4.3% with the wedged footwear. The changes in ankle moment and curved sprinting speed observed in the current study supports the notion that the moment generation at the ankle joint may be a performance constraint for curved sprinting. PMID:23022207
Kamarudin, Kamarulzaman; Mamduh, Syed Muhammad; Shakaff, Ali Yeon Md; Zakaria, Ammar
2014-12-05
This paper presents a performance analysis of two open-source, laser scanner-based Simultaneous Localization and Mapping (SLAM) techniques (i.e., Gmapping and Hector SLAM) using a Microsoft Kinect to replace the laser sensor. Furthermore, the paper proposes a new system integration approach whereby a Linux virtual machine is used to run the open source SLAM algorithms. The experiments were conducted in two different environments; a small room with no features and a typical office corridor with desks and chairs. Using the data logged from real-time experiments, each SLAM technique was simulated and tested with different parameter settings. The results show that the system is able to achieve real time SLAM operation. The system implementation offers a simple and reliable way to compare the performance of Windows-based SLAM algorithm with the algorithms typically implemented in a Robot Operating System (ROS). The results also indicate that certain modifications to the default laser scanner-based parameters are able to improve the map accuracy. However, the limited field of view and range of Kinect's depth sensor often causes the map to be inaccurate, especially in featureless areas, therefore the Kinect sensor is not a direct replacement for a laser scanner, but rather offers a feasible alternative for 2D SLAM tasks.
Kamarudin, Kamarulzaman; Mamduh, Syed Muhammad; Shakaff, Ali Yeon Md; Zakaria, Ammar
2014-01-01
This paper presents a performance analysis of two open-source, laser scanner-based Simultaneous Localization and Mapping (SLAM) techniques (i.e., Gmapping and Hector SLAM) using a Microsoft Kinect to replace the laser sensor. Furthermore, the paper proposes a new system integration approach whereby a Linux virtual machine is used to run the open source SLAM algorithms. The experiments were conducted in two different environments; a small room with no features and a typical office corridor with desks and chairs. Using the data logged from real-time experiments, each SLAM technique was simulated and tested with different parameter settings. The results show that the system is able to achieve real time SLAM operation. The system implementation offers a simple and reliable way to compare the performance of Windows-based SLAM algorithm with the algorithms typically implemented in a Robot Operating System (ROS). The results also indicate that certain modifications to the default laser scanner-based parameters are able to improve the map accuracy. However, the limited field of view and range of Kinect's depth sensor often causes the map to be inaccurate, especially in featureless areas, therefore the Kinect sensor is not a direct replacement for a laser scanner, but rather offers a feasible alternative for 2D SLAM tasks. PMID:25490595
Kamarudin, Kamarulzaman; Mamduh, Syed Muhammad; Shakaff, Ali Yeon Md; Zakaria, Ammar
2014-01-01
This paper presents a performance analysis of two open-source, laser scanner-based Simultaneous Localization and Mapping (SLAM) techniques (i.e., Gmapping and Hector SLAM) using a Microsoft Kinect to replace the laser sensor. Furthermore, the paper proposes a new system integration approach whereby a Linux virtual machine is used to run the open source SLAM algorithms. The experiments were conducted in two different environments; a small room with no features and a typical office corridor with desks and chairs. Using the data logged from real-time experiments, each SLAM technique was simulated and tested with different parameter settings. The results show that the system is able to achieve real time SLAM operation. The system implementation offers a simple and reliable way to compare the performance of Windows-based SLAM algorithm with the algorithms typically implemented in a Robot Operating System (ROS). The results also indicate that certain modifications to the default laser scanner-based parameters are able to improve the map accuracy. However, the limited field of view and range of Kinect's depth sensor often causes the map to be inaccurate, especially in featureless areas, therefore the Kinect sensor is not a direct replacement for a laser scanner, but rather offers a feasible alternative for 2D SLAM tasks. PMID:25490595
Bender, Andreas; Mussa, Hamse Y; Glen, Robert C; Reiling, Stephan
2004-01-01
/50 split of training and test compounds. In the case of sparse training data, binary kernel discrimination is found to be superior on this particular dataset. On a third dataset, the atom environment descriptor shows higher retrieval rates than other 2D fingerprints tested here when used in combination with the Tanimoto similarity coefficient. Feature selection is shown to be a crucial step in determining the performance of the algorithm. The representation of molecules by atom environments is found to be more effective than Unity fingerprints for the type of biological receptor similarity calculations examined here. Combining information prior to scoring and including information about inactive compounds, as in the Bayesian classifier and binary kernel discrimination, is found to be superior to posterior data fusion (in the datasets tested here).
NASA Astrophysics Data System (ADS)
Plesniak, Daniel H.; Bulusu, Kartik V.; Plesniak, Michael W.
2012-11-01
Interpretation of complex flow patterns observed in this study of a model curved artery required characterization of multiple, low-circulation secondary flow structures that were observed during the late systolic deceleration and diastolic phases under physiological inflow conditions. Phase-locked, planar vorticity PIV data were acquired at various cross-sectional locations of the 180-degree bent tube model. High circulation, deformed Dean- and Lyne-type vortices were observed during early stages of deceleration, while several smaller scale, highly deformed, low-circulation vortical patterns appeared in the core and near-wall regions during late systolic deceleration and diastolic phases. Due to the multiplicity of vortical scales and shapes, anisotropic 2D Ricker wavelets were used for coherent structure detection in a continuous wavelet transform algorithm (PIVlet 1.2). Our bio-inspired study is geared towards understanding whether optimizing the shape of the wavelet kernel will enable better resolution of several low-circulation, multi-scale secondary flow morphologies and whether new insights into the dynamics of arterial secondary flow structures can accordingly be gained. Supported by the National Science Foundation, Grant No. CBET-0828903 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).
NASA Astrophysics Data System (ADS)
Savoini, P.; Lembege, B.
2014-12-01
The ion foreshock located upstream of the Earth's bow shock is populated with ions reflected back by the shock front. In-situ spacecraft measurements have clearly established the existence of two distinct populations in the upstream of the quasi-perpendicular shock region (i.e. for 45o ≤ ΘBn≤ 90o, where ΘBn is the angle between the shock normal and the upstream magnetostatic field): (i) field-aligned ion beams (or 'FAB') characterized by a gyrotropic distribution, and (ii) gyro-phase bunched ions (or 'GPB') characterized by a NON gyrotropic distribution, which exhibits a non-vanishing perpendicular bulk velocity. The use of 2D PIC simulations where full curvature effects, time of flight effects and both electrons and ions dynamics are fully described, has evidenced that the shock front itself can be the possible source of these two characteristic populations. A recent analysis has evidenced that both populations can be discriminated in terms of interaction time (Δtinter) with the shock front. 'GPB' and 'FAB' populations are characterized by a short (Δtinter ~ 1 τci) and much larger (Δtinter ≥ 2 τci) interaction time respectively, where τci is the ion upstream gyroperiod. In addition, present statistical results evidence that: (i) backstreaming ions are splitted into 'FAB' and 'GPB' populations depending on their injection angle when hitting the shock front (defined between the local normal to the shock front and the gyration velocity vector). (ii) As a consequence, ion trajectories strongly differ between the 'FAB' and 'GPB' populations at the shock front. In particular, 'FAB' ions suffer multi-bounces along the curved front whereas 'GPB' ions make only one bounce. Such differences may explain why the 'FAB' population loses their gyro-phase coherency and become gyrotropic which is not the case for the 'GPB'. Then, the differences observed between 'FAB' and 'GPB' populations do not involve some distinct reflection processes as often claimed in the
NASA Astrophysics Data System (ADS)
Zhang, Weiyu; Zhu, Xiaoshu; Chen, Xuguang; Zhou, Yiming; Tang, Yawen; Ding, Liangxin; Wu, Ping
2016-05-01
Metal oxide nanohybrids with uniform dimensions and controlled architectures possess unique compositional and structural superiorities, and thus harbor promising potential for a series of applications in energy, catalysis, and sensing systems. Herein, we propose a facile, general, and scalable cyano-bridged coordination polymer hydrogel-derived thermal-oxidation route for the construction of main-group metal and transition-metal heterometallic oxide nanohybrids with controlled constituents and architectures. The formation of Sn-Fe binary oxide nanohybrids has been demonstrated as an example by using cyano-bridged Sn(iv)-Fe(ii) bimetallic coordination polymer hydrogels (i.e., SnCl4-K4Fe(CN)6 cyanogels, Sn-Fe cyanogels) as precursors. The physicochemical properties of Sn-Fe cyanogels with different Sn/Fe ratios have been systematically examined, and it is found that perfect Sn-Fe cyanogels without unbridged Sn(iv) or Fe(ii) can be formed with Sn/Fe ratios from 2 : 1 to 1 : 2. More importantly, the simple adjustment of Sn/Fe ratios in the Sn-Fe cyanogel precursors can realize flexible dimensional control of the Sn-Fe binary oxide nanohybrids, and 2D/1D SnO2-Fe2O3 hierarchitectures, 2D SnO2-Fe2O3 nanosheets, and 3D SnO2-Fe2O3 networks have been synthesized using the Sn-Fe 1 : 2, Sn-Fe 1 : 1, and Sn-Fe 2 : 1 cyanogels as precursors, respectively. To demonstrate their compositional/structural superiorities and potential applications, the lithium-storage utilization of the Sn-Fe binary oxide nanohybrids has been selected as an objective application, and the nanohybrids exhibit Sn/Fe ratio-dependent lithium-storage performance. As a representative example, the 2D/1D SnO2-Fe2O3 hierarchitectures manifest markedly enhanced Li-storage performance in terms of reversible capacities and cycling stability in comparison with their constituent units, i.e., bare SnO2 nanosheets and Fe2O3 nanorods. The proposed cyanogel-derived thermal-oxidation strategy could open up new
Advanced Modified High Performance Synthetic Jet Actuator with Curved Chamber
NASA Technical Reports Server (NTRS)
Xu, Tian-Bing (Inventor); Su, Ji (Inventor); Jiang, Xiaoning (Inventor)
2014-01-01
The advanced modified high performance synthetic jet actuator with optimized curvature shape chamber (ASJA-M) is a synthetic jet actuator (SJA) with a lower volume reservoir or chamber. A curved chamber is used, instead of the conventional cylinder chamber, to reduce the dead volume of the jet chamber and increase the efficiency of the synthetic jet actuator. The shape of the curvature corresponds to the maximum displacement (deformation) profile of the electroactive diaphragm. The jet velocity and mass flow rate for the ASJA-M will be several times higher than conventional piezoelectric actuators.
NASA Astrophysics Data System (ADS)
Choi, Doo-Won; Jeon, Min-Gyu; Cho, Gyeong-Rae; Kamimoto, Takahiro; Deguchi, Yoshihiro; Doh, Deog-Hee
2016-02-01
Performance improvement was attained in data reconstructions of 2-dimensional tunable diode laser absorption spectroscopy (TDLAS). Multiplicative Algebraic Reconstruction Technique (MART) algorithm was adopted for data reconstruction. The data obtained in an experiment for the measurement of temperature and concentration fields of gas flows were used. The measurement theory is based upon the Beer-Lambert law, and the measurement system consists of a tunable laser, collimators, detectors, and an analyzer. Methane was used as a fuel for combustion with air in the Bunsen-type burner. The data used for the reconstruction are from the optical signals of 8-laser beams passed on a cross-section of the methane flame. The performances of MART algorithm in data reconstruction were validated and compared with those obtained by Algebraic Reconstruction Technique (ART) algorithm.
Performance of Replica-Exchange Wang-Landau Sampling for the 2D Ising Model: A Brief Survey
Zhao, Yiwei; Cheung, Siu Wun; Li, Ying Wai; Eisenbach, Markus
2014-01-01
We report a brief performance study of the replica-exchange Wang-Landau algorithm, a recently proposed parallel realization of Wang-Landau sampling, using the 2D Ising model as a test case. The simulation time is found to scale inversely with the square root of the number of subwindows (and thus number of processors) used to span the global parameter space. We also investigate the time profiles for random walkers in dierent subwindows to complete iterations, which will aid the development of and adaptive load-balancing scheme.
Xiao, Fei; Song, Jibin; Gao, Hongcai; Zan, Xiaoli; Xu, Rong; Duan, Hongwei
2012-01-24
The development of flexible electrodes is of considerable current interest because of the increasing demand for modern electronics, portable medical products, and compact energy devices. We report a modular approach to fabricating high-performance flexible electrodes by structurally integrating 2D-assemblies of nanoparticles with freestanding graphene paper. We have shown that the 2D array of gold nanoparticles at oil-water interfaces can be transferred on freestanding graphene oxide paper, leading to a monolayer of densely packed gold nanoparticles of uniform sizes loaded on graphene oxide paper. One major finding is that the postassembly electrochemical reduction of graphene oxide paper restores the ordered structure and electron-transport properties of graphene, and gives rise to robust and biocompatible freestanding electrodes with outstanding electrocatalytic activities, which have been manifested by the sensitive and selective detection of two model analytes: glucose and hydrogen peroxide (H(2)O(2)) secreted by live cells. The modular nature of this approach coupled with recent progress in nanocrystal synthesis and surface engineering opens new possibilities to systematically study the dependence of catalytic performance on the structural parameters and chemical compositions of the nanocrystals.
Qi, Yuhang; Xu, Qun; Wang, Yun; Yan, Bo; Ren, Yumei; Chen, Zhimin
2016-02-23
Molybdenum disulfide (MoS2) is a promising non-precious-metal catalyst, but its performance is limited by the density of active sites and poor electrical transport. Its metallic 1T phase possesses higher photoelectrocatalytic activity. Thus, how to efficiently increase the concentration of the 1T phase in the exfoliated two-dimensiaonal (2D) MoS2 nanosheets is an important premise. In this work, we propose a strategy to prepare a 2D heterostructure of MoS2 nanosheets using supercritical CO2-induced phase engineering to form metallic 1T-MoS2. Theoretical calculations and experimental results demonstrate that the introduced CO2 in the 2H-MoS2 host can prompt the transformation of partial 2H-MoS2 lattices into 1T-MoS2. Moreover, the electrical coupling and synergistic effect between 2H and 1T phases can greatly facilitate the efficient electron transfer from the active sites of MoS2, which significantly improves the photocatalytic performance. PMID:26840941
NASA Astrophysics Data System (ADS)
Liu, Zhen; Qu, Hengliang; Shi, Hongda; Hu, Gexing; Hyun, Beom-Soo
2016-09-01
Tidal current energy is renewable and sustainable, which is a promising alternative energy resource for the future electricity supply. The straight-bladed vertical-axis turbine is regarded as a useful tool to capture the tidal current energy especially under low-speed conditions. A 2D unsteady numerical model based on Ansys-Fluent 12.0 is established to conduct the numerical simulation, which is validated by the corresponding experimental data. For the unsteady calculations, the SST model, 2×105 and 0.01 s are selected as the proper turbulence model, mesh number, and time step, respectively. Detailed contours of the velocity distributions around the rotor blade foils have been provided for a flow field analysis. The tip speed ratio (TSR) determines the azimuth angle of the appearance of the torque peak, which occurs once for a blade in a single revolution. It is also found that simply increasing the incident flow velocity could not improve the turbine performance accordingly. The peaks of the averaged power and torque coefficients appear at TSRs of 2.1 and 1.8, respectively. Furthermore, several shapes of the duct augmentation are proposed to improve the turbine performance by contracting the flow path gradually from the open mouth of the duct to the rotor. The duct augmentation can significantly enhance the power and torque output. Furthermore, the elliptic shape enables the best performance of the turbine. The numerical results prove the capability of the present 2D model for the unsteady hydrodynamics and an operating performance analysis of the vertical tidal stream turbine.
NASA Astrophysics Data System (ADS)
Pires, O.; Munduate, X.; Ceyhan, O.; Jacobs, M.; Madsen, J.; Schepers, J. G.
2016-09-01
2D wind tunnel tests at high Reynolds numbers have been done within the EU FP7 AVATAR project (Advanced Aerodynamic Tools of lArge Rotors) on the DU00-W-212 airfoil and at two different test facilities: the DNW High Pressure Wind Tunnel in Gottingen (HDG) and the LM Wind Power in-house wind tunnel. Two conditions of Reynolds numbers have been performed in both tests: 3 and 6 million. The Mach number and turbulence intensity values are similar in both wind tunnels at the 3 million Reynolds number test, while they are significantly different at 6 million Reynolds number. The paper presents a comparison of the data obtained from the two wind tunnels, showing good repeatability at 3 million Reynolds number and differences at 6 million Reynolds number that are consistent with the different Mach number and turbulence intensity values.
Performance of Electroluminescent Flats for Precision Light Curve Photometry
NASA Astrophysics Data System (ADS)
Avril, Ryan L.; Oberst, T. E.
2014-01-01
We measure of the quality of flat field frames (flats) taken using an electroluminescent (EL) panel versus both dome and sky flats for purposes of calibrating visual CCD images. Classic dome and sky flats can both suffer from overall gradients and local irregularities. EL panel flats have recently grown in popularity as a third alternative, based partly on their potential to be free of such defects. We assess the flats based on their contributions to the RMS noise of long-duration light curves constructed via differential aperture photometry. The noise levels explored range from ~ 1 - few mmag, as needed for the ground-based detection of transiting planets. The target and reference stars are deliberately permitted to drift across the CCD in order to probe pixel-to-pixel variations. Both the filter and focus are varied during the tests - the former to probe color variation in the flats, and the latter because defocusing tends to average out pixel-to-pixel variations that the flats are intended to remove. All tests were performed at the Westminster College Observatory (WCO), which belongs to the Kilodegree Extremely Little Telescope (KELT)-North follow-up network.
NASA Astrophysics Data System (ADS)
Uneri, A.; Otake, Y.; Wang, A. S.; Kleinszig, G.; Vogt, S.; Gallia, G. L.; Rigamonti, D.; Wolinsky, J.-P.; Gokaslan, Ziya L.; Khanna, A. J.; Siewerdsen, J. H.
2014-03-01
An algorithm for 3D-2D registration of CT and x-ray projections has been developed using dual projection views to provide 3D localization with accuracy exceeding that of conventional tracking systems. The registration framework employs a normalized gradient information (NGI) similarity metric and covariance matrix adaptation evolution strategy (CMAES) to solve for the patient pose in 6 degrees of freedom. Registration performance was evaluated in anthropomorphic head and chest phantoms, as well as a human torso cadaver, using C-arm projection views acquired at angular separations (Δ𝜃) ranging 0-178°. Registration accuracy was assessed in terms target registration error (TRE) and compared to that of an electromagnetic tracker. Studies evaluated the influence of C-arm magnification, x-ray dose, and preoperative CT slice thickness on registration accuracy and the minimum angular separation required to achieve TRE ~2 mm. The results indicate that Δ𝜃 as small as 10-20° is adequate to achieve TRE <2 mm with 95% confidence, comparable or superior to that of commercial trackers. The method allows direct registration of preoperative CT and planning data to intraoperative fluoroscopy, providing 3D localization free from conventional limitations associated with external fiducial markers, stereotactic frames, trackers, and manual registration. The studies support potential application to percutaneous spine procedures and intracranial neurosurgery.
Afik, Eldad
2015-01-01
Three-dimensional particle tracking is an essential tool in studying dynamics under the microscope, namely, fluid dynamics in microfluidic devices, bacteria taxis, cellular trafficking. The 3d position can be determined using 2d imaging alone by measuring the diffraction rings generated by an out-of-focus fluorescent particle, imaged on a single camera. Here I present a ring detection algorithm exhibiting a high detection rate, which is robust to the challenges arising from ring occlusion, inclusions and overlaps, and allows resolving particles even when near to each other. It is capable of real time analysis thanks to its high performance and low memory footprint. The proposed algorithm, an offspring of the circle Hough transform, addresses the need to efficiently trace the trajectories of many particles concurrently, when their number in not necessarily fixed, by solving a classification problem, and overcomes the challenges of finding local maxima in the complex parameter space which results from ring clusters and noise. Several algorithmic concepts introduced here can be advantageous in other cases, particularly when dealing with noisy and sparse data. The implementation is based on open-source and cross-platform software packages only, making it easy to distribute and modify. It is implemented in a microfluidic experiment allowing real-time multi-particle tracking at 70 Hz, achieving a detection rate which exceeds 94% and only 1% false-detection. PMID:26329642
NASA Astrophysics Data System (ADS)
Savoini, P.; Lembege, B.
2015-12-01
The ion foreshock located upstream of the Earth's shock wave is populated with ions having interacted with the shock, and then, reflected back with an high energy gain. Spacecrafts have clearly established the existence of two distinct populations in the quasi-perpendicular shock region (i.e. for 45° ≤ ΘBn ≤ 90°, where ΘBn is the angle between the shock normal and the upstream magnetic field) : (i) field-aligned ion beams or « FAB » characterized by a gyrotropic distribution, and (ii) gyro-phase bunched ions or « GPB » characterized by a NON gyrotropic distribution. One of the important unresolved problem is the exact origin of the particles contributing to these two populations. To our knowledge, it was the first time that full-particle simulations have been performed including self-consistently the shock front curvature and nonstationarity, and the time-of-flight effects. Our analysis evidences that these two backstreaming populations may be reflected by the front itself and can be differentiated both in terms of interaction time and trajectory within the shock front. In particular, simulations evidence that "GPB" population is characterized by a short interaction time (ΔTinter = 1 to 2 τci) while the "FAB" population corresponds to a much larger time range (from 1 τci to 10 τci), where tci is the upstream ion gyroperiod. Present individual ion trajectories evidence that "FAB" population shows a strong perpendicular drift at the shock front (i.e. strong dependence of the pitch angle to the perpendicular velocity) whereas the "GPB" population shows no perpendicular drift (i.e. its pitch angle is mainly driven by the parallel velocity). Such differences explain why the "FAB" population loses their gyro-phase coherency and become gyrotropic which is not the case for the "GPB". This important result was not expected and greatly simplifies the question of their origin.
NASA Astrophysics Data System (ADS)
Kikuchi, Shigeta; Yamasaki, Nobuhiko; Yamagata, Akihiro
2013-02-01
Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers is discussed. The computational fluid dynamics (CFD) analysis of a turbocharger compressor validated for the compressor model with the straight pipe applied to the compressor with the curved pipe are executed, and the deterioration of the performance for the curved pipe is confirmed. It is also found that the deterioration of compressor performance is caused by the interaction of the secondary flow and the impeller.
SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES
Findeisen, Krzysztof; Hillenbrand, Lynne; Cody, Ann Marie
2015-01-10
Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs.
Simulated Performance of Timescale Metrics for Aperiodic Light Curves
NASA Astrophysics Data System (ADS)
Findeisen, Krzysztof; Cody, Ann Marie; Hillenbrand, Lynne
2015-01-01
Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs.
NASA Astrophysics Data System (ADS)
Foray, Vincent; Gibert, Patricia; Desouhant, Emmanuel
2011-08-01
Environmental variability is expected to be important in shaping performance curves, reaction norms of phenotypic traits related to fitness. Models predict that the breadth of performance curves should increase with environmental variability at the expense of maximal performance. In this study, we compared the thermal performance curves of two sympatric populations of the parasitoid Venturia canescens that were observed under contrasting thermal regimes in their respective preferred habitats and differing in their modes of reproduction. Our results confirm the large effect of developmental temperature on phenotypic traits of insects and demonstrate that thelytokous and arrhenotokous wasps respond differently to temperature during development, in agreement with model predictions. For traits related to fecundity, thelytokous parasitoids, which usually occur in stable thermal conditions, exhibit specialist performance curves, maximising their reproductive success under a restricted range of temperature. In contrast, arrhenotokous parasitoids, which occur in variable climates, exhibit generalist performance curves, in keeping with the hypothesis "jack of all temperatures, master of none".
Effect of different breath alcohol concentrations on driving performance in horizontal curves.
Zhang, Xingjian; Zhao, Xiaohua; Du, Hongji; Ma, Jianming; Rong, Jian
2014-11-01
Driving under the influence of alcohol on curved roadway segments has a higher risk than driving on straight segments. To explore the effect of different breath alcohol concentration (BrAC) levels on driving performance in roadway curves, a driving simulation experiment was designed to collect 25 participants' driving performance parameters (i.e., speed and lane position) under the influence of 4 BrAC levels (0.00%, 0.03%, 0.06% and 0.09%) on 6 types of roadway curves (3 radii×2 turning directions). Driving performance data for 22 participants were collected successfully. Then the average and standard deviation of the two parameters were analyzed, considering the entire curve and different sections of the curve, respectively. The results show that the speed throughout curves is higher when drinking and driving than during sober driving. The significant interaction between alcohol and radius exists in the middle and tangent segments after a curve exit, indicating that a small radius can reduce speed at high BrAC levels. The significant impairment of alcohol on the stability of speed occurs mainly in the curve section between the point of curve (PC) and point of tangent (PT), with no impairment noted in tangent sections. The stability of speed is significantly worsened at higher BrAC levels. Alcohol and radius have interactive effects on the standard deviation of speed in the entry segment of curves, indicating that the small radius amplifies the instability of speed at high BrAC levels. For lateral movement, drivers tend to travel on the right side of the lane when drinking and driving, mainly in the approach and middle segments of curves. Higher BrAC levels worsen the stability of lateral movement in every segment of the curve, regardless of its radius and turning direction. The results are expected to provide reference for detecting the drinking and driving state.
Zhao, Xiaohua; Wu, Yiping; Rong, Jian; Ma, Jianming
2015-02-01
To develop a practicable and clear guideline for implementing Chevrons on China's highways, it is necessary to understand the effect of Chevrons on driving performance in different roadway geometries. Using a driving simulator, this study tests the effect of China's Chevrons on vehicle speed and lane position on two-lane rural highway horizontal curves with different roadway geometries. The results showed a significant effect of Chevrons on speed reduction, and this function was not significantly affected by curve radius but was statistically affected by curve direction. The speed reduction caused by Chevrons was also significant at the approach of curve, middle of curve and point of tangent. The 85th percentile speed was also markedly lower when Chevrons were present. We also found a significant effect of Chevrons in encouraging participants to drive the vehicle with a more proper lane position at the first half of curves; and this function was slightly affected by curve radius. Meanwhile, the effect of Chevrons on keeping drivers staying in a more stable lane position was also statistically significant at the second half of curves. In sharp curves, the function of Chevrons to make drivers keep a stable lane position was lost. Besides, the impact of curve direction on the function of Chevrons on lane position was always present, and drivers would drive slightly away from Chevrons. Regardless of the curve radius, China's Chevrons at horizontal curves provide an advance warning, speed control and lane position guide for traffic on the nearside of Chevrons. Besides, combing with the function of Chevrons on preventing excessive speed and the benefit to make drivers keep a more proper lane position, China's Chevrons appear to be of great benefit to reduce crashes (e.g., run-off-road) in curves. PMID:25525973
On the optimal performance and universal design curves of galloping energy harvesters
NASA Astrophysics Data System (ADS)
Bibo, A.; Daqaq, M. F.
2014-01-01
In this letter, we establish a universal relationship between a dimensionless version of the output power and the flow speed for galloping energy harvesters. This relationship yields a unique curve, which is only sensitive to the aerodynamic properties of the bluff body, but is, otherwise, invariant under any changes in the mechanical and electrical design parameters of the harvester. The curve permits a simple and direct comparative analysis of the energy harvesting performance of different bluff bodies so long that the other design parameters are kept constant. The universal curve is also shown to facilitate the optimization analysis, thereby providing significant insight into the optimal performance conditions.
NASA Technical Reports Server (NTRS)
Lakew, Brook; Aslam, S.
2011-01-01
Detectors with better performance than the current thermopile detectors that operate at room temperature will be needed at the focal plane of far-infrared instruments on future planetary exploration missions. We will present an update on recent results from the 2-D array of MgB2 thermal detectors being currently developed at NASA Goddard. Noise and sensitivity results will be presented and compared to thermal detectors currently in use on planetary missions.
Gaschler, Robert; Progscha, Johanna; Smallbone, Kieran; Ram, Nilam; Bilalić, Merim
2014-01-01
Learning curves have been proposed as an adequate description of learning processes, no matter whether the processes manifest within minutes or across years. Different mechanisms underlying skill acquisition can lead to differences in the shape of learning curves. In the current study, we analyze the tournament performance data of 1383 chess players who begin competing at young age and play tournaments for at least 10 years. We analyze the performance development with the goal to test the adequacy of learning curves, and the skill acquisition theories they are based on, for describing and predicting expertise acquisition. On the one hand, we show that the skill acquisition theories implying a negative exponential learning curve do a better job in both describing early performance gains and predicting later trajectories of chess performance than those theories implying a power function learning curve. On the other hand, the learning curves of a large proportion of players show systematic qualitative deviations from the predictions of either type of skill acquisition theory. While skill acquisition theories predict larger performance gains in early years and smaller gains in later years, a substantial number of players begin to show substantial improvements with a delay of several years (and no improvement in the first years), deviations not fully accounted for by quantity of practice. The current work adds to the debate on how learning processes on a small time scale combine to large-scale changes. PMID:25202292
Gaschler, Robert; Progscha, Johanna; Smallbone, Kieran; Ram, Nilam; Bilalić, Merim
2014-01-01
Learning curves have been proposed as an adequate description of learning processes, no matter whether the processes manifest within minutes or across years. Different mechanisms underlying skill acquisition can lead to differences in the shape of learning curves. In the current study, we analyze the tournament performance data of 1383 chess players who begin competing at young age and play tournaments for at least 10 years. We analyze the performance development with the goal to test the adequacy of learning curves, and the skill acquisition theories they are based on, for describing and predicting expertise acquisition. On the one hand, we show that the skill acquisition theories implying a negative exponential learning curve do a better job in both describing early performance gains and predicting later trajectories of chess performance than those theories implying a power function learning curve. On the other hand, the learning curves of a large proportion of players show systematic qualitative deviations from the predictions of either type of skill acquisition theory. While skill acquisition theories predict larger performance gains in early years and smaller gains in later years, a substantial number of players begin to show substantial improvements with a delay of several years (and no improvement in the first years), deviations not fully accounted for by quantity of practice. The current work adds to the debate on how learning processes on a small time scale combine to large-scale changes.
Al-Khalili, Sereen M; Coppoc, Gordon L
2014-01-01
The hypothesis for the research described in this article was that viewing an interactive two-dimensional (2D) or three-dimensional (3D) stereoscopic pre-laboratory video would improve efficiency and learning in the laboratory. A first-year DVM class was divided into 21 dissection teams of four students each. Primary variables were method of preparation (2D, 3D, or laboratory manual) and dissection region (thorax, abdomen, or pelvis). Teams were randomly assigned to a group (A, B, or C) in a crossover design experiment so that all students experienced each of the modes of preparation, but with different regions of the canine anatomy. All students were instructed to study normal course materials and the laboratory manual, the Guide, before coming to the laboratory session and to use them during the actual dissection as usual. Video groups were given a DVD with an interactive 10-12 minute video to view for the first 30 minutes of the laboratory session, while non-video groups were instructed to review the Guide. All groups were allowed 45 minutes to dissect the assigned section and find a list of assigned structures, after which all groups took a post-dissection quiz and attitudinal survey. The 2D groups performed better than the Guide groups (p=.028) on the post-dissection quiz, despite the fact that only a minority of the 2D-group students studied the Guide as instructed. There was no significant difference (p>.05) between 2D and 3D groups on the post-dissection quiz. Students preferred videos over the Guide. PMID:24418924
Al-Khalili, Sereen M; Coppoc, Gordon L
2014-01-01
The hypothesis for the research described in this article was that viewing an interactive two-dimensional (2D) or three-dimensional (3D) stereoscopic pre-laboratory video would improve efficiency and learning in the laboratory. A first-year DVM class was divided into 21 dissection teams of four students each. Primary variables were method of preparation (2D, 3D, or laboratory manual) and dissection region (thorax, abdomen, or pelvis). Teams were randomly assigned to a group (A, B, or C) in a crossover design experiment so that all students experienced each of the modes of preparation, but with different regions of the canine anatomy. All students were instructed to study normal course materials and the laboratory manual, the Guide, before coming to the laboratory session and to use them during the actual dissection as usual. Video groups were given a DVD with an interactive 10-12 minute video to view for the first 30 minutes of the laboratory session, while non-video groups were instructed to review the Guide. All groups were allowed 45 minutes to dissect the assigned section and find a list of assigned structures, after which all groups took a post-dissection quiz and attitudinal survey. The 2D groups performed better than the Guide groups (p=.028) on the post-dissection quiz, despite the fact that only a minority of the 2D-group students studied the Guide as instructed. There was no significant difference (p>.05) between 2D and 3D groups on the post-dissection quiz. Students preferred videos over the Guide.
Performance Demonstration Based Probablity of Detection (POD) Curves for Fatigue Cracks in Piping
Gosselin, Stephen R.; Simonen, Fredric A.; Heasler, Patrick G.; Becker, F. L.; Doctor, Steven R.; Carter, R. G.
2005-07-01
This paper evaluates non-destructive examination (NDE) detection capabilities for fatigue cracks in piping. Industry performance demonstration initiative (PDI) data for fatigue crack detection were used to develop a matrix of statistically based probability of detection (POD) curves that consider various NDE performance factors. Seven primary performance factors were identified – Material, Crack Geometry/Type, NDE Examination Access, NDE Procedure, Examiner Qualification, Pipe Diameter, and Pipe Wall Thickness. A database of 16,181 NDE performance observations, with 18 fields associated with each observation, was created and used to develop statistically based POD curves for 42 stainless steel and 14 carbon steel performance cases. Subsequent comparisons of the POD fits for each of the cases showed that excellent NDE performance for fatigue cracks can be expected for ferritic materials. Very little difference was observed between the POD curves for the 14 carbon steel performance cases considered in this study and NDE performance could therefore be represented by a single POD curve. For stainless steel, very good performance can also be expected for circumferential cracks located on the same side of the weld from which the NDE examination is made. POD depended primarily on component thickness. Three POD curves for stainless steel were prepared. Best estimate and the associated 95% confidence bounds for POD versas through-wall depth logistic regression digital data are provided. Probabilistic fracture mechanics (PFM) calculations were performed to compare best estimate leak probabilities obtained from both the new performance-based POD curves and previous PFM models. This work was performed under joint funding by EPRI and the U.S. Department of Energy (DOE), Office of Nuclear Energy Science and Technology’s Nuclear Energy Plant Optimization (NEPO) program.
Wind turbine performance: Methods and criteria for reliability of measured power curves
Griffin, D.A.
1996-12-31
In order to evaluate the performance of prototype turbines, and to quantify incremental changes in performance through field testing, Advanced Wind Turbines (AWT) has been developing methods and requirements for power curve measurement. In this paper, field test data is used to illustrate several issues and trends which have resulted from this work. Averaging and binning processes, data hours per wind-speed bin, wind turbulence levels, and anemometry methods are all shown to have significant impacts on the resulting power curves. Criteria are given by which the AWT power curves show a high degree of repeatability, and these criteria are compared and contrasted with current published standards for power curve measurement. 6 refs., 5 figs., 5 tabs.
Zou, Xuming; Huang, Chun-Wei; Wang, Lifeng; Yin, Long-Jing; Li, Wenqing; Wang, Jingli; Wu, Bin; Liu, Yunqi; Yao, Qian; Jiang, Changzhong; Wu, Wen-Wei; He, Lin; Chen, Shanshan; Ho, Johnny C; Liao, Lei
2016-03-01
A unique design of a hexagonal boron nitride (h-BN)/HfO2 dielectric heterostructure stack is demonstrated, with few-layer h-BN to alleviate the surface optical phonon scattering, followed by high-κ HfO2 deposition to suppress Coulombic impurity scattering so that high-performance top-gated two-dimensional semiconductor transistors are achieved. Furthermore, this dielectric stack can also be extended to GaN-based transistors to enhance their performance.
NASA Astrophysics Data System (ADS)
García-Salaberri, P. A.; Vera, M.
2015-07-01
The influence of assembly compression on the performance of liquid-feed DMFCs under methanol-limiting conditions is explored by means of a 2D/1D multiphysics across-the-channel model. The numerical formulation incorporates a comprehensive 2D description of the anode GDL, including two-phase phenomena, non-uniform anisotropic transport properties, and electrical contact resistances at the GDL/BPP interface. GDL effective properties are evaluated using empirical data corresponding to Toray® carbon paper. A simplified but physically sound 1D description, locally coupled to the 2D anode GDL model, is adopted to describe transport processes in the MPLs, membrane and cathode GDL, whereas the catalyst layers are treated as infinitely thin surfaces. Good agreement is found between the numerical results and previous experimental data. The interplay between assembly compression, bipolar plate material, and channel configuration is also investigated. The results show that there is an optimum GDL compression ratio in terms of overall power density, the optimal compression level being strongly dependent on bipolar plate material. Beyond the optimum, the detrimental effect of compression is larger in non-parallel flow fields due to the additional reduction of methanol transported by under-rib convection. The results suggest that, under certain conditions, this transport mechanism could be more important than diffusion in the anode of liquid-feed DMFCs.
Neuschmelting, Volker; Burton, Neal C.; Lockau, Hannah; Urich, Alexander; Harmsen, Stefan; Ntziachristos, Vasilis; Kircher, Moritz F.
2015-01-01
A handheld approach to optoacoustic imaging is essential for the clinical translation. The first 2- and 3-dimensional handheld multispectral optoacoustic tomography (MSOT) probes featuring real-time unmixing have recently been developed. Imaging performance of both probes was determined in vitro and in a brain melanoma metastasis mouse model in vivo. T1-weighted MR images were acquired for anatomical reference. The limit of detection of melanoma cells in vitro was significantly lower using the 2D than the 3D probe. The signal decrease was more profound in relation to depth with the 3D versus the 2D probe. Both approaches were capable of imaging the melanoma tumors qualitatively at all time points. Quantitatively, the 2D approach enabled closer anatomical resemblance of the tumor compared to the 3D probe, particularly at depths beyond 3 mm. The 3D probe was shown to be superior for rapid 3D imaging and, thus, holds promise for more superficial target structures. PMID:27069872
Bhartia, Bhavesh; Bacher, Nadav; Jayaraman, Sundaramurthy; Khatib, Salam; Song, Jing; Guo, Shifeng; Troadec, Cedric; Puniredd, Sreenivasa Reddy; Srinivasan, Madapusi Palavedu; Haick, Hossam
2015-07-15
Formation of dense monolayers with proven atmospheric stability using simple fabrication conditions remains a major challenge for potential applications such as (bio)sensors, solar cells, surfaces for growth of biological cells, and molecular, organic, and plastic electronics. Here, we demonstrate a single-step modification of organophosphonic acids (OPA) on 1D and 2D structures using supercritical carbon dioxide (SCCO2) as a processing medium, with high stability and significantly shorter processing times than those obtained by the conventional physisorption-chemisorption method (2.5 h vs 48-60 h).The advantages of this approach in terms of stability and atmospheric resistivity are demonstrated on various 2D materials, such as indium-tin-oxide (ITO) and 2D Si surfaces. The advantage of the reported approach on electronic and sensing devices is demonstrated by Si nanowire field effect transistors (SiNW FETs), which have shown a few orders of magnitude higher electrical and sensing performances, compared with devices obtained by conventional approaches. The compatibility of the reported approach with various materials and its simple implementation with a single reactor makes it easily scalable for various applications. PMID:26087766
Bhartia, Bhavesh; Bacher, Nadav; Jayaraman, Sundaramurthy; Khatib, Salam; Song, Jing; Guo, Shifeng; Troadec, Cedric; Puniredd, Sreenivasa Reddy; Srinivasan, Madapusi Palavedu; Haick, Hossam
2015-07-15
Formation of dense monolayers with proven atmospheric stability using simple fabrication conditions remains a major challenge for potential applications such as (bio)sensors, solar cells, surfaces for growth of biological cells, and molecular, organic, and plastic electronics. Here, we demonstrate a single-step modification of organophosphonic acids (OPA) on 1D and 2D structures using supercritical carbon dioxide (SCCO2) as a processing medium, with high stability and significantly shorter processing times than those obtained by the conventional physisorption-chemisorption method (2.5 h vs 48-60 h).The advantages of this approach in terms of stability and atmospheric resistivity are demonstrated on various 2D materials, such as indium-tin-oxide (ITO) and 2D Si surfaces. The advantage of the reported approach on electronic and sensing devices is demonstrated by Si nanowire field effect transistors (SiNW FETs), which have shown a few orders of magnitude higher electrical and sensing performances, compared with devices obtained by conventional approaches. The compatibility of the reported approach with various materials and its simple implementation with a single reactor makes it easily scalable for various applications.
A method to enhance the curve negotiation performance of HTS Maglev
NASA Astrophysics Data System (ADS)
Che, T.; Gou, Y. F.; Deng, Z. G.; Zheng, J.; Zheng, B. T.; Chen, P.
2015-09-01
High temperature superconducting (HTS) Maglev has attracted more and more attention due to its special self-stable characteristic, and much work has been done to achieve its actual application, but the research about the curve negotiation is not systematic and comprehensive. In this paper, we focused on the change of the lateral displacements of the Maglev vehicle when going through curves under different velocities, and studied the change of the electromagnetic forces through experimental methods. Experimental results show that setting an appropriate initial eccentric distance (ED), which is the distance between the center of the bulk unit and the center of the permanent magnet guideway (PMG), when cooling the bulks is favorable for the Maglev system’s curve negotiation. This work will provide some available suggestions for improving the curve negotiation performance of the HTS Maglev system.
Shim, Jaewoo; Oh, Aely; Kang, Dong-Ho; Oh, Seyong; Jang, Sung Kyu; Jeon, Jaeho; Jeon, Min Hwan; Kim, Minwoo; Choi, Changhwan; Lee, Jaehyeong; Lee, Sungjoo; Yeom, Geun Young; Song, Young Jae; Park, Jin-Hong
2016-08-01
A high-performance ReS2 -based thin-film transistor and photodetector with high on/off-current ratio (10(4) ), high mobility (7.6 cm(2) V(-1) s(-1) ), high photoresponsivity (2.5 × 10(7) A W(-1) ), and fast temporal response (rising and decaying time of 670 ms and 5.6 s, respectively) through O2 plasma treatment is reported. PMID:27206245
Comparing and contrasting 2D versus 1D performance modeling in NV-IPM v1.6
NASA Astrophysics Data System (ADS)
Hixson, Jonathan G.; Teaney, Brian P.
2016-05-01
Version 1.6 of the Night Vision Integrated Performance Model (NV-IPM) introduced two-dimensional Modulation Transfer Function (MTF) and noise signals within the model architecture. These two-dimensional signals enable the model to more accurately treat systems with non-separable MTF components. These non-separable MTF components may be introduced by optical elements, electronic post-processing, or atmospheric effects. In this paper we discuss the differences between the new two-dimensional signal architecture and the one-dimensional separable representation used in earlier versions of the model and highlight some cases which demonstrate the utility of the two-dimensional signals.
Characterizing Decision-Analysis Performances of Risk Prediction Models Using ADAPT Curves
Lee, Wen-Chung; Wu, Yun-Chun
2016-01-01
Abstract The area under the receiver operating characteristic curve is a widely used index to characterize the performance of diagnostic tests and prediction models. However, the index does not explicitly acknowledge the utilities of risk predictions. Moreover, for most clinical settings, what counts is whether a prediction model can guide therapeutic decisions in a way that improves patient outcomes, rather than to simply update probabilities. Based on decision theory, the authors propose an alternative index, the “average deviation about the probability threshold” (ADAPT). An ADAPT curve (a plot of ADAPT value against the probability threshold) neatly characterizes the decision-analysis performances of a risk prediction model. Several prediction models can be compared for their ADAPT values at a chosen probability threshold, for a range of plausible threshold values, or for the whole ADAPT curves. This should greatly facilitate the selection of diagnostic tests and prediction models. PMID:26765451
ERIC Educational Resources Information Center
Wang, Chee Keng John; Pyun, Do Young; Liu, Woon Chia; Lim, Boon San Coral; Li, Fuzhong
2013-01-01
Using a multilevel latent growth curve modeling (LGCM) approach, this study examined longitudinal change in levels of physical fitness performance over time (i.e. four years) in young adolescents aged from 12-13 years. The sample consisted of 6622 students from 138 secondary schools in Singapore. Initial analyses found between-school variation on…
Measuring Curved Crystal Performance for a High Resolution, Imaging X-ray Spectrometer
Michael Haugh and Richard Stewart
2010-06-07
This paper describes the design, crystal selection, and crystal testing for a vertical Johann spectrometer operating in the 13 keV range to measure ion Doppler broadening in inertial confinement plasmas. The spectrometer is designed to use thin, curved, mica crystals to achieve a resolving power of E/ΔE>2000. A number of natural mica crystals were screened for flatness and X-ray diffraction width to find samples of sufficient perfection for use in the instrument. Procedures to select and mount high quality mica samples are discussed. A diode-type X-ray source coupled to a dual goniometer arrangement was used to measure the crystal reflectivity curve. A procedure was developed for evaluating the goniometer performance using a set of diffraction grade Si crystals. This goniometer system was invaluable for identifying the best original crystals for further use and developing the techniques to select satisfactory curved crystals for the spectrometer.
NASA Astrophysics Data System (ADS)
Boehm, Holger F.; Link, Thomas M.; Monetti, Roberto A.; Mueller, Dirk; Rummeny, Ernst J.; Raeth, Christoph W.
2005-04-01
Osteoporosis is a metabolic bone disease leading to de-mineralization and increased risk of fracture. The two major factors that determine the biomechanical competence of bone are the degree of mineralization and the micro-architectural integrity. Today, modern imaging modalities (high resolution MRI, micro-CT) are capable of depicting structural details of trabecular bone tissue. From the image data, structural properties obtained by quantitative measures are analysed with respect to the presence of osteoporotic fractures of the spine (in-vivo) or correlated with biomechanical strength as derived from destructive testing (in-vitro). Fairly well established are linear structural measures in 2D that are originally adopted from standard histo-morphometry. Recently, non-linear techniques in 2D and 3D based on the scaling index method (SIM), the standard Hough transform (SHT), and the Minkowski Functionals (MF) have been introduced, which show excellent performance in predicting bone strength and fracture risk. However, little is known about the performance of the various parameters with respect to monitoring structural changes due to progression of osteoporosis or as a result of medical treatment. In this contribution, we generate models of trabecular bone with pre-defined structural properties which are exposed to simulated osteoclastic activity. We apply linear and non-linear texture measures to the models and analyse their performance with respect to detecting architectural changes. This study demonstrates, that the texture measures are capable of monitoring structural changes of complex model data. The diagnostic potential varies for the different parameters and is found to depend on the topological composition of the model and initial "bone density". In our models, non-linear texture measures tend to react more sensitively to small structural changes than linear measures. Best performance is observed for the 3rd and 4th Minkowski Functionals and for the scaling
Direct tension and fracture resistance curves of ultra high performance marine composite materials
NASA Astrophysics Data System (ADS)
Wu, Xiang-Guo; Han, Sang-Mook
2008-09-01
Fracture behavior is one of the most important, yet still little understood properties of ultra-high performance cementitious composites (UHPCC), a new marine structural engineering material. Research on the fracture and direct tension behavior of UHPCC was carried out. The constitution law of UHPCC was divided into three phases: pre-partial debonding, partial debonding, and pullout phases. A direct tension constitution law was constructed based on the proposed fiber reinforcing parameter as a function of fiber volume fraction, fiber diameter and length, and fiber bonding strength. With the definition of linear crack shape, the energy release rate of UHPCC was derived and the R-curve equation was calculated from this. Loading tests of UHPCC using a three-point bending beam with an initial notch were carried out. The predictions from the proposed R-curve were in good agreement with the test results, indicating that the proposed R-curve accurately describes the fracture resistance of UHPCC. Introduction of a fiber reinforcement parameter bridges the fracture property R-curve and micro-composites’ mechanics parameters together. This has laid the foundation for further research into fracture properties based on micro-mechanics. The proposed tension constitution law and R-curve can be references for future UHPCC fracture evaluation.
Li, Songmei Wang, Bo; Li, Bin; Liu, Jianhua; Yu, Mei; Wu, Xiaoyu
2015-01-15
Highlights: • MFO/GN composites were synthesized by a facile in situ solvothermal approach. • The MFO microspheres are sandwiched between the graphene layers. • Each MFO microsphere is an interstitial cluster of nanoparticles. • The MFO/GN electrode exhibits an enhanced cyclability for Li-ion batteries anodes. - Abstract: In this study, two-dimensional (2D) sandwich-structured MnFe{sub 2}O{sub 4}/graphene (MFO/GN) composites are synthesized by a facile in situ solvothermal approach, using cetyltrimethylammonium bromide (CTAB) as cationic surfactant. As a consequence, the nanocomposites of MFO/GN self-assembled into a 2D sandwich structure, in which the interstitial cluster structure of microsphere-type MnFe{sub 2}O{sub 4} is sandwiched between the graphene layers. This special structure of the MFO/GN composites used as anodes for lithium-ion batteries will be favorable for the maximum accessible surface of electroactive materials, fast diffusion of lithium ions and migration of electron, and elastomeric space to accommodate volume changes during the discharge–charge processes. The as-synthesized MFO/GN composites deliver a high specific reversible capacity of 987.95 mA h g{sup −1} at a current density of 200 mA g{sup −1}, a good capacity retention of 69.27% after 80 cycles and excellent rate performance for lithium storage.
Mathematical analysis of the heart rate performance curve during incremental exercise testing.
Rosic, G; Pantovic, S; Niciforovic, J; Colovic, V; Rankovic, V; Obradovic, Z; Rosic, Mirko
2011-03-01
In this study we performed laboratory treadmill protocols of increasing load. Heart rate was continuously recorded and blood lactate concentration was measured for determination of lactate threshold by means of LTD-max and LT4.0 methods.Our results indicate that the shape of heart rate performance curve (HRPC) during incremental testing depends on the applied exercise protocol (change of initial speed and the step of running speed increase, with the constant stage duration). Depending on the applied protocol, the HRPC can be described by linear, polynomial (S-shaped), and exponential mathematical expression.We presented mathematical procedure for estimation of heart rate threshold points at the level of LTD-max and LT4.0, by means of exponential curve and its relative deflection from the initial trend line (tangent line to exponential curve at the point of starting heart rate). The relative deflection of exponential curve from the initial trend line at the level of LTD-max and/or LT4.0 can be defined, based on the slope of the initial trend line. Using originally developed software that allows mathematical analysis of heart rate-load relation, LTD-max and/or LT4.0 can be estimated without direct measurement of blood lactate concentration.
NASA Astrophysics Data System (ADS)
Horowitz, Larry L.; Brendel, Gary F.
1999-08-01
This paper continues the development of a fundamental, algorithm-independent view of the ATR performance that can be achieved using SAR data. Such ATR performance predictions are intended to enable evaluation of performance tradeoffs for SAR designs, including both parameter selections (e.g., bandwidth and transmit power) and added domains of SAR observation, such as 3-D, full polarimetry, aspect diversity, and/or frequency diversity. Using a Bayesian framework, we show target classification performance predictions for two tactical targets (either stationary with radar netting assumed deployed, or moving) using three different domains of observation: 1-D HRR (high-range-resolution radar), 2-D SAR, and 3-D SAR. Comparisons of the three domains are made at 3m, 1m, 0.5m and 0.3m range and cross-range resolutions. The discussion of 3-D SAR includes parameter tradeoffs of various height resolutions at the target, and various numbers of sensors. For each measurement modality, we list some of the unique sensitivities which could cause performance degradations.
Reliability of the Woodway Curve(TM) Non-Motorized Treadmill for Assessing Anaerobic Performance.
Gonzalez, Adam M; Wells, Adam J; Hoffman, Jay R; Stout, Jeffrey R; Fragala, Maren S; Mangine, Gerald T; McCormack, William P; Townsend, Jeremy R; Jajtner, Adam R; Emerson, Nadia S; Robinson Iv, Edward H
2013-01-01
A curved treadmill offers a practical method of assessing anaerobic power by enabling unrestricted running motion and greater sport specificity. The purpose of this research was to determine reliability of a curved treadmill (cTM) sprint test and to compare performance measures to the traditional Wingate anaerobic power test (WAnT) performed on a cycle ergometer. Thirty-two recreationally active men and women (22.4 ± 2.8 yrs; 1.73 ± 0.08 m; 74. 2 ± 13.2 kg) performed four familiarization trials on cTM, followed by two randomly assigned experimental trials consisting of one 30-second maximum effort on either cTM or WAnT. Each trial was separated by at least 48 hours. Repeated measures analysis of variance (ANOVA), interclass correlations (ICC), standard error of measurement (SEM), and minimal differences (MD) were used to determine reliability of familiarization trials on cTM, and Pearson product moment correlations were calculated to compare cTM and WAnT. ANOVA results showed significant differences (p < 0.05) during the four familiarization trials. Post hoc analysis showed significant differences (p < 0. 05) between the first two trials. Familiarization trials 3 and 4 showed a high reliability for each performance variable (distance: ICC2,1 = 0.969, %SEM = 2.645, p = 0.157; mean velocity: ICC2,1 = 0. 969, %SEM = 2.622, p = 0.173; peak velocity: ICC2,1 = 0.966, %SEM = 3.142, p = 0.033; mean power: ICC2,1 = 0.940, %SEM = 4.140, p = 0.093; and peak power: ICC2,1 = 0.887, %SEM = 11.244, p = 0.669). Participants elicited an average peak power of 1050.4 ± 338.5 Watts on cTM and 1031.4 ± 349.8 Watts on WAnT. Pearson product moment coefficients indicated high correlations between peak power, mean power, and peak velocity (r = 0.75, p < 0.001; r = 0.84, p < 0.001; and r = 0.76, p < 0. 001, respectively) derived from cTM and WAnT. In conclusion, results suggest that after two familiarization trials, cTM is a reliable sprint test for recreationally active men and women
Pálfy, Tamás Gábor; Gribovszki, Zoltán; Langergraber, Günter
2015-01-01
The 4,000 PE (700 m(3)/d) wastewater treatment plant at Balf, Hungary was based on sequencing batch reactor technology with phosphorus precipitation as the tertiary step. Its effluent met quality thresholds on average, with above-threshold peaks mainly in winter. The HYDRUS/CW2D model package (PC Progress s.r.o.) was used to simulate the treatment performance of a horizontal flow constructed wetland for polishing effluent. The goal of this study was to provide design-supportive information about the suitability of the proposed wetland and to prove the applicability of the computational tool used to gain that information. The simulations showed that the wetland with the proposed layout could not tackle peaks in NH4-N. Other effluent thresholds could be met, including chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen, total inorganic nitrogen and total phosphorus. The tool was unable to simulate COD and BOD5 removal in periods when the electron acceptors were depleted because anaerobic processes are not modelled. Using a tool of such complexity for designing carries excessive work demands and involves many uncertainties. The simulation study highlighted that the model used could still facilitate the design of an effective system by showing the weaknesses of a test scenario as it was demonstrated. PMID:25860697
Pálfy, Tamás Gábor; Gribovszki, Zoltán; Langergraber, Günter
2015-01-01
The 4,000 PE (700 m(3)/d) wastewater treatment plant at Balf, Hungary was based on sequencing batch reactor technology with phosphorus precipitation as the tertiary step. Its effluent met quality thresholds on average, with above-threshold peaks mainly in winter. The HYDRUS/CW2D model package (PC Progress s.r.o.) was used to simulate the treatment performance of a horizontal flow constructed wetland for polishing effluent. The goal of this study was to provide design-supportive information about the suitability of the proposed wetland and to prove the applicability of the computational tool used to gain that information. The simulations showed that the wetland with the proposed layout could not tackle peaks in NH4-N. Other effluent thresholds could be met, including chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen, total inorganic nitrogen and total phosphorus. The tool was unable to simulate COD and BOD5 removal in periods when the electron acceptors were depleted because anaerobic processes are not modelled. Using a tool of such complexity for designing carries excessive work demands and involves many uncertainties. The simulation study highlighted that the model used could still facilitate the design of an effective system by showing the weaknesses of a test scenario as it was demonstrated.
Kingsolver, Joel G; Woods, H Arthur
2016-03-01
Thermal performance curves have been widely used to model the ecological responses of ectotherms to variable thermal environments and climate change. Such models ignore the effects of time dependence-the temporal pattern and duration of temperature exposure-on performance. We developed and solved a simple mathematical model for growth rate of ectotherms, combining thermal performance curves for ingestion rate with the temporal dynamics of gene expression and protein production in response to high temperatures to predict temporal patterns of growth rate in constant and diurnally fluctuating temperatures. We used the model to explore the effects of heat shock proteins on larval growth rates of Manduca sexta. The model correctly captures two empirical patterns for larval growth rate: first, maximal growth rate and optimal temperature decline with increasing duration of temperature exposure; second, mean growth rates decline with time in diurnally fluctuating temperatures at higher mean temperatures. These qualitative results apply broadly to cases where proteins or other molecules produced in response to high temperatures reduce growth rates. We discuss some of the critical assumptions and predictions of the model and suggest potential extensions and alternatives. Incorporating time-dependent effects will be essential for making more realistic predictions about the physiological and ecological consequences of temperature fluctuations and climate change. PMID:26913942
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.
Connecting thermal performance curve variation to the genotype: a multivariate QTL approach.
Latimer, C A L; Foley, B R; Chenoweth, S F
2015-01-01
Thermal performance curves (TPCs) are continuous reaction norms that describe the relationship between organismal performance and temperature and are useful for understanding trade-offs involved in thermal adaptation. Although thermal trade-offs such as those between generalists and specialists or between hot- and cold-adapted phenotypes are known to be genetically variable and evolve during thermal adaptation, little is known of the genetic basis to TPCs - specifically, the loci involved and the directionality of their effects across different temperatures. To address this, we took a multivariate approach, mapping quantitative trait loci (QTL) for locomotor activity TPCs in the fly, Drosophila serrata, using a panel of 76 recombinant inbred lines. The distribution of additive genetic (co)variance in the mapping population was remarkably similar to the distribution of mutational (co)variance for these traits. We detected 11 TPC QTL in females and 4 in males. Multivariate QTL effects were closely aligned with the major axes genetic (co)variation between temperatures; most QTL effects corresponded to variation for either overall increases or decreases in activity with a smaller number indicating possible trade-offs between activity at high and low temperatures. QTL representing changes in curve shape such as the 'generalist-specialist' trade-off, thought key to thermal adaptation, were poorly represented in the data. We discuss these results in the light of genetic constraints on thermal adaptation.
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
Modeling KDP Bulk Damage Curves for Prediction of Large-Area Damage Performance
Runkel, M.; Sharp, R.
1999-12-16
Over the past two years extensive experimentation has been carded out to determine the nature of bulk damage in KDP. Automated damage testing with small beams has made it possible to rapidly investigate damage statistics and its connection to growth parameter Variation. Over this time we have built up an encyclopedia of many damage curves but only relatively few samples have been tested with large beams. The scarcity of data makes it difficult to estimate how future crystals will perform on the NIF, and the campaign nature of large beam testing is not suitable for efficient testing of many samples with rapid turn-around, it is therefore desirable to have analytical tools in place that could make reliable predictions of large-beam performance based on small-beam damage probability measurements. To that end, we discuss the application of exponential and power law damage evolution within the framework of Poisson statistics in this memo. We describe the results of fitting these models to various damage probability curves on KDP including the heavily investigated KDP214 samples. We find that both models are capable of fitting the damage probability S-curves quite well but there are multiple parameter sets for each model that produce comparable {chi}{sup 2} values. In addition, the fit parameters from the exponential model do not agree well with the measured evolution from large-beam OSL experiments where pinpoint density was shown to evolve according to n(F)=n{sub 0}exp(bF). The largest discrepancy is in determination of the b values. For the O'Connell formalism the power law case developed here, we find that the best-fit powers have approximately the same magnitude as the Weibull exponent of Feit's formalism, but it is difficult to extract information about the defect concentration using the O'Connell approach. In addition, we found that the power law case provides slightly better {chi}{sup 2} values in roughly half of the cases. We discuss these results in terms of
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.
Photovoltaic performance parameters at the nanoscale from in situ I-V curve measurements
NASA Astrophysics Data System (ADS)
Naseem, Sadia; Tennyson, Elizabeth; Leite, Marina
Monocrystalline photovoltaic (PV) devices exhibit higher efficiencies than polycrystalline devices, but the high manufacturing costs associated with single crystal solar cells pose a hindrance to their wide implementation. Polycrystalline CuInxGa(1 - x)Se2 (CIGS) material with high optical absorbance and low cost/Watt, is a promising alternative. Yet, the efficiency of this low-cost technology is still substantially lower than the theoretical values estimated by the Shockley-Queisser limit. This is likely due to microstructural non-uniformities, which cannot be accessed by macroscopic light I-V measurements. Therefore, we spatially resolve the electrical response of these devices by `local' I-Vs. For that, we utilize a 100x objective as a local excitation source and LabVIEW to map the PV performance with sub-micronscale resolution through extrapolation of key parameters from pixel by pixel I-V curves. Extraction of performance parameters such as short-circuit current, opencircuit voltage fill factor, and maximum power point can provide useful information regarding optimal microstructural characteristics. This information is not only valuable for CIGS-based devices, but also will be an essential tool for maximizing performance across all PV technologies.
Chagas-Neto, Francisco Abaeté; Nogueira-Barbosa, Marcello Henrique; Lorenzato, Mário Müller; Salim, Rodrigo; Kfuri-Junior, Maurício; Crema, Michel Daoud
2016-01-01
Objective To compare the diagnostic performance of the three-dimensional turbo spin-echo (3D TSE) magnetic resonance imaging (MRI) technique with the performance of the standard two-dimensional turbo spin-echo (2D TSE) protocol at 1.5 T, in the detection of meniscal and ligament tears. Materials and Methods Thirty-eight patients were imaged twice, first with a standard multiplanar 2D TSE MR technique, and then with a 3D TSE technique, both in the same 1.5 T MRI scanner. The patients underwent knee arthroscopy within the first three days after the MRI. Using arthroscopy as the reference standard, we determined the diagnostic performance and agreement. Results For detecting anterior cruciate ligament tears, the 3D TSE and routine 2D TSE techniques showed similar values for sensitivity (93% and 93%, respectively) and specificity (80% and 85%, respectively). For detecting medial meniscal tears, the two techniques also had similar sensitivity (85% and 83%, respectively) and specificity (68% and 71%, respectively). In addition, for detecting lateral meniscal tears, the two techniques had similar sensitivity (58% and 54%, respectively) and specificity (82% and 92%, respectively). There was a substantial to almost perfect intraobserver and interobserver agreement when comparing the readings for both techniques. Conclusion The 3D TSE technique has a diagnostic performance similar to that of the routine 2D TSE protocol for detecting meniscal and anterior cruciate ligament tears at 1.5 T, with the advantage of faster acquisition. PMID:27141127
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.
Investigation of Injector Slot Geometry on Curved-Diffuser Aerodynamic Performance
NASA Technical Reports Server (NTRS)
Silva, Odlanier
2004-01-01
The Compressor Branch vision is to be recognized as world-class leaders in research for fluid mechanics of compressors. Its mission is to conduct research and develop technology to advance the state of the art of compressors and transfer new technology to U.S. industries. Maintain partnerships with U.S. industries, universities, and other government organizations. Maintain a balance between customers focused and long range research. Flow control comprises enabling technologies to meet compression system performance requirements driven by emissions and fuel reduction goals (e.g., in UEET), missions (e.g., access-to-space), aerodynamically aggressive vehicle configurations (e.g., UAV and future blended wing body configurations with highly distorted inlets), and cost goals (e.g., in VAATE). The compression system requirements include increased efficiency, power-to-weight, and adaptability (i.e., robustness in terms of wide operability, distortion tolerance, and engine system health and reliability). The compressor flow control task comprises efforts to develop, demonstrate, and transfer adaptive flow control technology to industry to increase aerodynamic loading at current blade row loss levels, to enable adaptive1 y wide operability, and to develop plant models for adaptive compression systems. In this context, flow control is the controlled modification of a flow field by a deliberate means beyond the natural (uncontrolled) shaping of the solid surfaces that define the principal flow path. The objective of the compressor flow control task is to develop and apply techniques that control circulation, aerodynamic blockage, and entropy production in order to enhance the performance and operability of compression systems for advanced aero-propulsion applications. This summer I would be working with a curved-diffuser because it simulates what happens with flow in the stator blades in the compressor. With this experiment I will be doing some data analysis and parametric
Fraser, H. S.; Naimi, S.; Long, W. J.
2000-01-01
INTRODUCTION: Evaluation of computer programs which generate multiple diagnoses can be hampered by a lack of effective, well recognized performance metrics. We have developed a method to calculate mean sensitivity and specificity for multiple diagnoses and generate ROC curves. METHODS: Data came from a clinical evaluation of the Heart Disease Program (HDP). Sensitivity, specificity, positive and negative predictive value (PPV, NPV) were calculated for each diagnosis type in the study. A weighted mean of overall sensitivity and specificity was derived and used to create an ROC curve. Alternative metrics Comprehensiveness and Relevance were calculated for each case and compared to the other measures. RESULTS: Weighted mean sensitivity closely matched Comprehensiveness and mean PPV matched Relevance. Plotting the Physician's sensitivity and specificity on the ROC curve showed that their discrimination was similar to the HDP but sensitivity was significantly lower. CONCLUSIONS: These metrics give a clear picture of a program's diagnostic performance and allow straightforward comparison between different programs and different studies. PMID:11079884
Shen, Jianfeng; Dong, Pei; Baines, Robert; Xu, Xiaowei; Zhang, Zhuqing; Ajayan, Pulickel M; Ye, Mingxin
2016-07-28
Novel ternary electrode materials based on graphene, NiCo2S4, and transition metal dichalcogenides (TMDs) were designed and fabricated with the intention of exploiting synergistic effects conducive to supercapacitive energy storage. Compared to NiCo2S4-g-MoSe2, the NiCo2S4-g-MoS2 electrode exhibited higher specific capacitance, enhanced rate capability (1002 F g(-1) even at 5 A g(-1), 6.01 F cm(-2) at a current density of 25 mA cm(-2)) and cycling stability (94.8% retention of its original capacity after cycling 4000 times). The mechanism was proposed and this pioneering work will be helpful in making judicious choices of which 2D materials to be selected for supercapacitor applications in the future. PMID:27353837
Optical performance of random anti-reflection structures on curved surfaces
NASA Astrophysics Data System (ADS)
Taylor, C.; Major, K. J.; Joshi, R.; Busse, L. E.; Frantz, J.; Sanghera, J. S.; Aggarwal, I. D.; Poutous, M. K.
2015-03-01
Random anti-reflection structured surfaces (rARSS) have been reported to improve transmittance of optical-grade fused silica planar substrates to values greater than 99%. These textures are achieved using reactive-ion etching techniques and often result in transmitted spectra with no measurable interference effects (fringes) for a wide range of wavelengths. The inductively-coupled reactive ion plasma (ICP-RIE) used in the fabrication process to etch the rARSS is anisotropic, and thus well-suited for planar components. The improvement in spectral transmission has been found to be independent of optical incidence angles, for values from 0° to ±30°. Qualifying and quantifying the rARSS performance on curved substrates, such as concave and convex lenses, is required to optimize the fabrication of a desirable AR effect on opticalpower elements. In this work, rARSS was fabricated on fused silica plano-convex and plano-concave lenses, using an optimized ICP-RIE process, to maximize optical transmission in the range from 500 nm to 1100 nm. Results are presented from optical transmission tests of matched sets of varying curvature lenses with rARSS at a wavelength of 633nm. The transmission was measured as a function of radial distance from the apex of each lens, and shows the anisotropic dependence of the etch process. The transmittance profiles between the different sphericity of the tested lenses as well as the matched sets of concave and convex surfaces are compared. The measured angle-of-incidence dependence of planar silica versus silica lenses with rARSS is also presented.
1998-08-01
The technical memorandum is intended to discuss the detailed procedure required for carrying out the statistical analyses of historical pavement condition data for building pavement performance curves. This chapter assumes the availability of the historical data in a spreadsheet format (Microsoft{trademark} Excel) that has been retrieved from the master (pavement management system) database.
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.
Technology Transfer Automated Retrieval System (TEKTRAN)
The objective of this work was to evaluate eight closed-form unimodal analytical expressions that describe the soil-water retention curve over the complete range of soil water contents. To meet this objective, the eight models were compared in terms of their accuracy (root mean square error, RMSE), ...
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.
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.
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
The cumulative ash curve: a best tool to evaluate complete mill performance.
Sakhare, Suresh D; Inamdar, Aashitosh A
2014-04-01
Slick test is carried out by a flour miller to qualitatively segregate the flour from different streams in a roller flour mill. This test is done manually by pressing flour samples on tray using thin bladed paddle (the slick) and inspecting color or dress of the sample. However, the test is subjective and totally depends on human judgment. Cumulative ash curve relates to cumulative flour ash content and cumulative flour yield, which could help a flour miller to be more precise while selecting flour streams for different needs. In this study, cleaning and conditioning of wheat was carried out in the pilot plant of International School of Milling Technology (ISMT). Further, roller flour milling of wheat was done. Flour from different streams (four breaks, five reductions) was collected. Each flour stream was analyzed for ash content using standard AACC methods. The analytical values of ash content were used to plot the cumulative ash curve. It was found that ash content increased in the break passages from first to last break, with exception of first break (ash content 0.71%). An increase in percentage of ash was observed in the reduction passages (C1 to C5), however, C3 ash (0.76%) was slightly higher than that of C4 (0.65%). Higher yield of flour with minimum ash content was obtained from the front reduction passages C1 and C2; whereas, the break passages and the tail end reduction passages produce less flour with higher ash content.
NASA Astrophysics Data System (ADS)
Summers, Jason E.; Torres, Rendell R.; Shimizu, Yasushi; Jaffe, J. Christopher
2002-05-01
The conditions under which the high-frequency, diffuse-field model of coupled rooms is a valid approximation to geometrical acoustics have been examined by comparison with ray-tracing predictions of decay curves in two and three room systems. Results particular to coupled rooms were noted. Because nonexponential decay shape is sensitive to both decay rates and relative energy densities, corrections to these parameters meaningfully improved the diffuse-field model. Variations in the free-path distribution of each subroom, introduced by coupling, complicated the use of improved decay models. Also, the expected decrease in energy density with distance from the source was found to result in spatial dependence of decay shape for certain coupling geometries. Insights from this study were used in the construction of diffuse-field and geometrical computer models of Bass Hall, a 2056 seat multipurpose auditorium with an acoustically coupled stage house. Preliminary results indicate that high-frequency decay curves in each of the subrooms predicted by geometrical acoustics are well matched to the predictions of diffuse-field models. The use of both models as prediction and design tools is assessed by comparison at high frequencies with measurements made during occupied and unoccupied conditions. [Research supported by the Bass Foundation.
Chiu, Po-Lin; Li, Xueming; Li, Zongli; Beckett, Brian; Brilot, Axel F; Grigorieff, Nikolaus; Agard, David A; Cheng, Yifan; Walz, Thomas
2015-11-01
The K2 Summit camera was initially the only commercially available direct electron detection camera that was optimized for high-speed counting of primary electrons and was also the only one that implemented centroiding so that the resolution of the camera can be extended beyond the Nyquist limit set by the physical pixel size. In this study, we used well-characterized two-dimensional crystals of the membrane protein aquaporin-0 to characterize the performance of the camera below and beyond the physical Nyquist limit and to measure the influence of electron dose rate on image amplitudes and phases.
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.
Phylogenetic tree construction based on 2D graphical representation
NASA Astrophysics Data System (ADS)
Liao, Bo; Shan, Xinzhou; Zhu, Wen; Li, Renfa
2006-04-01
A new approach based on the two-dimensional (2D) graphical representation of the whole genome sequence [Bo Liao, Chem. Phys. Lett., 401(2005) 196.] is proposed to analyze the phylogenetic relationships of genomes. The evolutionary distances are obtained through measuring the differences among the 2D curves. The fuzzy theory is used to construct phylogenetic tree. The phylogenetic relationships of H5N1 avian influenza virus illustrate the utility of our approach.
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.
NASA Astrophysics Data System (ADS)
Wu, Xuan; Xu, Rui; Zhu, Rongjiao; Wu, Rui; Zhang, Bin
2015-05-01
Engineering two-dimensional (2D) nanosheets into three-dimensional (3D) hierarchical structures is one of the great challenges in nanochemistry and materials science. We report a facile and simple chemical conversion route to fabricate 3D hierarchical nanosheet-based ZnSe microspheres by using 2D inorganic-organic hybrid ZnSe-DETA (DETA = diethylenetriamine) nanosheets as the starting precursors. The conversion mechanism involves the controlled depletion of the organic-component (DETA) from the hybrid precursors and the subsequent self-assembly of the remnant inorganic-component (ZnSe). The transformation reaction of ZnSe-DETA nanosheets is mainly influenced by the concentration of DETA in the reaction solution. We demonstrated that this organic-component depletion method could be extended to the synthesis of other hierarchical structures of metal sulfides. In addition, the obtained hierarchical nanosheet-based ZnSe microspheres exhibited outstanding performance in visible light photocatalytic degradation of methyl orange and were highly active for photocatalytic H2 production.Engineering two-dimensional (2D) nanosheets into three-dimensional (3D) hierarchical structures is one of the great challenges in nanochemistry and materials science. We report a facile and simple chemical conversion route to fabricate 3D hierarchical nanosheet-based ZnSe microspheres by using 2D inorganic-organic hybrid ZnSe-DETA (DETA = diethylenetriamine) nanosheets as the starting precursors. The conversion mechanism involves the controlled depletion of the organic-component (DETA) from the hybrid precursors and the subsequent self-assembly of the remnant inorganic-component (ZnSe). The transformation reaction of ZnSe-DETA nanosheets is mainly influenced by the concentration of DETA in the reaction solution. We demonstrated that this organic-component depletion method could be extended to the synthesis of other hierarchical structures of metal sulfides. In addition, the obtained
NASA Technical Reports Server (NTRS)
Yang, T.; Hudson, W. G.; Nelson, C. D.
1973-01-01
The feasibility of designing short curved wall axially symmetrical subsonic diffusers utilizing suction through slots in the diffuser walls to prevent flow separation was investigated. A potential flow analysis was made, and a digital computer program was written for determining the diffuser wall contour for prescribed boundary conditions. The flow field included branch flow so that the suction slot geometry could be a part of the diffuser design. One bell shaped diffuser and three annular diffusers with area ratios of either 2.5:1 or 3:1 were designed, fabricated, and tested. Minimum suction requirements of metastable operation ranged from 6.3 percent to 12 percent when operating with inlet air velocities in the 1000 to 250 ft/sec (30 to 76 m/sec) range. For stable operation suction rates from 10 percent to 22 percent were required. In all cases the diffuser effectiveness was above 95 percent based on the conventional definition, and from 81 percent to 94 percent when the suction loss was accounted for. The exit velocity profiles were virtually flat with no more than + or - 9% variation over 95 percent of the exit area when operated with sufficient suction to prevent flow separation.
ERIC Educational Resources Information Center
Ackerman, Phillip L.; Shapiro, Stacey; Beier, Margaret E.
2011-01-01
When people choose a particular occupation, they presumably make an implicit judgment that they will perform well on a job at some point in the future, typically after extensive education and/or on-the-job experience. Research on learning and skill acquisition has pointed to a power law of practice, where large gains in performance come early in…
Assessment of ventilatory performance of athletes using the maximal expiratory flow-volume curve.
Bertholon, J F; Carles, J; Teillac, A
1986-04-01
We carried out a maximum expiratory flow-volume curve (MEFV) and a spirometric recording with 67 athletes of different ages (15-27 years) and disciplines (rowers, kayakists, cyclists, swimmers) and with 20 adult and 13 adolescent nonathletic controls of matching ages. These recordings were repeated, with athletes only, after 6-10 months of training. Significant differences between the groups of adult athletes and the controls were observed for some parameters, the most discriminating of which were, in order, the peak expiratory flow (PEF), the forced expiratory volume in the first second (FEV1), and the flow at 75% of the vital capacity (V75). The vital capacity (VC) itself was only higher in the rowers group. The adult athletes, when grouped together (n = 47), produced a higher flow at 50% of their VC (V50) than the control group (+15%, P less than 0.05) with no difference in the flow at 25% of VC (V25) nor in the VC. A study of the effects of training showed no evolution among high level athletes while increases of 14% of the PEF, 5% of the V75, and 7% of the FEV1 were found after 7-10 months of training in adolescents; the VC increased during that time by only 2.7%. The reproducibility of these ventilatory parameters after 6-8 months was studied with adult athletes. The upper limit of the variation (95% CLl) was 12% for the FEV1 and forced vital capacity (FVC), 18% for PEF, 21% for V75 and V50, and 40% for V25.(ABSTRACT TRUNCATED AT 250 WORDS)
Zimmerman, K.A.; Bahulkar, A.M.
1998-08-01
The use of a pavement management system provides a state highway agency with the tools necessary to conduct a multi-year analysis of the maintenance and rehabilitation needs within the state based on both current needs and expected future conditions. In order to adequately predict future conditions, pavement performance models must be developed to reflect the deterioration trends of the agency`s pavements. At the time the SDDOT pavement management system was implemented in 1994, the Department developed a new condition rating system to evaluate the existing conditions of the state maintained pavements. At the same time, expert-based pavement performance models were developed to approximate the deterioration patterns of the highways based on pavement families (groupings of pavements with similar characteristics). A recommendation from that study (SD93-14) was to update the curves based on historical performance once sufficient data had been collected.
Wu, Xuan; Xu, Rui; Zhu, Rongjiao; Wu, Rui; Zhang, Bin
2015-06-01
Engineering two-dimensional (2D) nanosheets into three-dimensional (3D) hierarchical structures is one of the great challenges in nanochemistry and materials science. We report a facile and simple chemical conversion route to fabricate 3D hierarchical nanosheet-based ZnSe microspheres by using 2D inorganic-organic hybrid ZnSe-DETA (DETA = diethylenetriamine) nanosheets as the starting precursors. The conversion mechanism involves the controlled depletion of the organic-component (DETA) from the hybrid precursors and the subsequent self-assembly of the remnant inorganic-component (ZnSe). The transformation reaction of ZnSe-DETA nanosheets is mainly influenced by the concentration of DETA in the reaction solution. We demonstrated that this organic-component depletion method could be extended to the synthesis of other hierarchical structures of metal sulfides. In addition, the obtained hierarchical nanosheet-based ZnSe microspheres exhibited outstanding performance in visible light photocatalytic degradation of methyl orange and were highly active for photocatalytic H2 production.
Postdivorce Family Stability and Changes in Adolescents' Academic Performance: A Growth-Curve Model
ERIC Educational Resources Information Center
Sun, Yongmin; Li, Yuanzhang
2009-01-01
Three waves of panel data from 7,897 adolescents in the National Education Longitudinal Studies have been used to investigate whether a stabilized postdivorce family environment benefits adolescents' academic performance trajectories. The analyses indicate that compared with peers who grow up in stable postdivorce families, children of divorce who…
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.
de Aguiar, Rafael Alves; Turnes, Tiago; Santos de Oliveira Cruz, Rogério; Salvador, Amadeo Félix; Caputo, Fabrizio
2015-05-01
To examine the influence of aerobic and anaerobic indices on repeated sprint (RS) performance and ability (RSA), 8 sprinters (SPR), 8 endurance runners (END), and 8 active participants (ACT) performed the following tests: (i) incremental test; (ii) 1-min test to determine first decay time constant of pulmonary oxygen uptake off-kinetics and parameters related to anaerobic energy supply, lactate exchange, and removal abilities from blood lactate kinetics; and (iii) RS test (ten 35-m sprints, departing every 20 s) to determine best (RSbest) and mean (RSmean) sprint times and percentage of sprint decrement (%Dec). While SPR had a 98%-100% likelihood of having the fastest RSbest (Cohen's d of 1.8 and 1.4 for ACT and END, respectively) and RSmean (2.1 and 0.9 for ACT and END, respectively), END presented a 97%-100% likelihood of having the lowest %Dec (0.9 and 2.2 for ACT and SPR, respectively). RSmean was very largely correlated with RSbest (r=0.85) and moderately correlated with estimates of anaerobic energy supply (r=-0.40 to -0.49). RSmean adjusted for RSbest (which indirectly reflects RSA) was largely correlated with lactate exchange ability (r=0.55). Our results confirm the importance of locomotor- and anaerobic-related variables to RS performance, and highlight the importance of disposal of selected metabolic by-products to RSA.
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.
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
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.
Focusing surface wave imaging with flexible 2D array
NASA Astrophysics Data System (ADS)
Zhou, Shiyuan; Fu, Junqiang; Li, Zhe; Xu, Chunguang; Xiao, Dingguo; Wang, Shaohan
2016-04-01
Curved surface is widely exist in key parts of energy and power equipment, such as, turbine blade cylinder block and so on. Cycling loading and harsh working condition of enable fatigue cracks appear on the surface. The crack should be found in time to avoid catastrophic damage to the equipment. A flexible 2D array transducer was developed. 2D Phased Array focusing method (2DPA), Mode-Spatial Double Phased focusing method (MSDPF) and the imaging method using the flexible 2D array probe are studied. Experiments using these focusing and imaging method are carried out. Surface crack image is obtained with both 2DPA and MSDPF focusing method. It have been proved that MSDPF can be more adaptable for curved surface and more calculate efficient than 2DPA.
Torres, D Diego
2015-03-01
Regarding the methods used to examine the early maternal age-child academic outcomes relationship, the extant literature has tended to examine change using statistical analyses that fail to appreciate that individuals vary in their rates of growth. Of the one study I have been able to find that employs a true growth model to estimate this relationship, the authors only controlled for characteristics of the maternal household after family formation; confounding background factors of mothers that might select them into early childbearing, a possible source of bias, were ignored. The authors' findings nonetheless suggested an inverse relationship between early maternal age, i.e., a first birth between the ages of 13 and 17, and Canadian adolescents' mean math performance at age 10. Early maternal age was not related to the linear slope of age. To elucidate whether the early maternal age-child academic outcomes association, treated in a growth context, is consistent with this finding, the present study built on it using US data and explored children's mathematics and reading trajectories from age 5 on. Its unique contribution is that it further explicitly controlled for maternal background factors and employed a three-level growth model with repeated measures of children nested within their mothers. Though the strength of the relationship varied between mean initial academic performance and mean academic growth, results confirmed that early maternal age was negatively related to children's mathematics and reading achievement, net of post-teen first birth child-specific and maternal household factors. Once maternal background factors were included, there was no statistically significant relationship between early maternal age and either children's mean initial mathematics and reading scores or their mean mathematics and reading growth.
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.
NASA Astrophysics Data System (ADS)
Said, Diego; Belinato, Gabriela; Sarmiento, Gustavo S.; Otero, Rosa L. Simencio; Totten, George E.; Gastón, Analía; Canale, Lauralice C. F.
2013-07-01
The potential use of vegetable oil-derived industrial oils continues to be of great interest because vegetable oils are relatively non-toxic, biodegradable, and they are a renewable basestock alternative to petroleum oil. However, the fatty ester components containing conjugated double bonds of the triglyceride structure of vegetable oils typically produce considerably poorer thermal-oxidative stability than that achievable with petroleum basestocks under typical use conditions. Typically, these conditions involve furnace loads of hot steel (850 °C), which are rapidly immersed and cooled to bath temperatures of approximately 50-60 °C. This is especially true when a vegetable oil is held in an open tank with agitation and exposed to air at elevated temperatures for extended periods of time (months or years). This paper will describe the thermal-oxidative stability and quenching performance of soybean oil and palm oil and the resulting impact on the heat transfer coefficient. These results are compared to typical fully formulated, commercially available accelerated (fast) and an unaccelerated (slow) petroleum oil-based quenchants.
Kuylenstierna, Carlotta; Björkström, Niklas K.; Andersson, Sofia K.; Sahlström, Peter; Bosnjak, Lidija; Paquin-Proulx, Dominic; Malmberg, Karl-Johan; Ljunggren, Hans-Gustaf; Moll, Markus; Sandberg, Johan K.
2012-01-01
Invariant NKT cells are important in the activation and regulation of immune responses. They can also function as CD1d-restricted killer cells. However, the role of activating innate NK cell receptors expressed on NKT cells in triggering cytolytic function is poorly characterized. Here, we initially confirmed that the cellular stress-ligand receptor NKG2D is expressed on CD4− NKT cells, whereas most CD4+ NKT cells lack this receptor. Interestingly, NKG2D+ NKT cells frequently expressed perforin, and both NKG2D and perforin localized at the site of contact with NKG2D ligand-expressing target cells. CD4− NKT cells degranulated in response to NKG2D engagement in a redirected activation assay independently of stimulation via their invariant TCR. NKT cells killed P815 cells coated with anti-NKG2D mAb and CD1d-negative K562 tumor target cells in an NKG2D-dependent manner. Furthermore, NKG2D engagement co-stimulated TCR-mediated NKT cell activation in response to endogenous CD1d-presented ligands or suboptimal levels of anti-CD3 triggering. These data indicate that the CD4− subset of human NKT cells can mediate direct lysis of target cells via NKG2D engagement independently of CD1d, and that NKG2D also functions as a co-stimulatory receptor in these cells. NKG2D thus plays both a direct and a co-stimulatory role in the activation of NKT cells. PMID:21590763
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.
Grevel, J.; Napoli, K.L.; Gibbons, S.; Kahan, B.D. )
1990-01-01
The measurement of areas under the concentration-time curve (AUC) was recently introduced as an alternative to trough level monitoring of cyclosporine therapy. The AUC is divided by the oral dosing interval to calculate an average concentration. All measurements are performed at clinical steady state. The initial evaluation of AUC monitoring showed advantages over trough level monitoring with concentrations of cyclosporine measured in serum by the polyclonal radioimmunoassay of Sandoz. This assay technique is no longer available and the following assays were performed in parallel during up to 173 AUC determinations in 51 consecutive renal transplant patients: polyclonal fluorescence polarization immunoassay of Abbott in serum, specific and nonspecific monoclonal radioimmunoassays using {sup 3}H and {sup 125}I tracers in serum and whole blood, and high performance liquid chromatography in whole blood. Both trough levels and average concentrations at steady state measured by those different techniques were significantly correlated with the oral dose. The best correlation (r2 = 0.54) was shown by average concentrations measured in whole blood by the specific monoclonal radioimmunoassay of Sandoz ({sup 3}H tracer). This monitoring technique was also associated with the smallest absolute error between repeated observations in the same patient while the oral dose rate remained the same or was changed. Both allegedly specific monoclonal radioimmunoassays (with {sup 3}H and {sup 125}I tracer) measured significantly higher concentrations than the liquid chromatography.
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.
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.
Simulating MEMS Chevron Actuator for Strain Engineering 2D Materials
NASA Astrophysics Data System (ADS)
Vutukuru, Mounika; Christopher, Jason; Bishop, David; Swan, Anna
2D materials pose an exciting paradigm shift in the world of electronics. These crystalline materials have demonstrated high electric and thermal conductivities and tensile strength, showing great potential as the new building blocks of basic electronic circuits. However, strain engineering 2D materials for novel devices remains a difficult experimental feat. We propose the integration of 2D materials with MEMS devices to investigate the strain dependence on material properties such as electrical and thermal conductivity, refractive index, mechanical elasticity, and band gap. MEMS Chevron actuators, provides the most accessible framework to study strain in 2D materials due to their high output force displacements for low input power. Here, we simulate Chevron actuators on COMSOL to optimize actuator design parameters and accurately capture the behavior of the devices while under the external force of a 2D material. Through stationary state analysis, we analyze the response of the device through IV characteristics, displacement and temperature curves. We conclude that the simulation precisely models the real-world device through experimental confirmation, proving that the integration of 2D materials with MEMS is a viable option for constructing novel strain engineered devices. The authors acknowledge support from NSF DMR1411008.
The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis
Shaheen, Eman De Keyzer, Frederik; Bosmans, Hilde; Ongeval, Chantal Van; Dance, David R.; Young, Kenneth C.
2014-08-15
Purpose: This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Methods: Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. Results: The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly
NASA Astrophysics Data System (ADS)
Le Roux, Olivier; Cornou, Cécile; Jongmans, Denis; Schwartz, Stéphane
2012-09-01
H/V spectral ratios are regularly used for estimating the bedrock depth in 1-D like basins exhibiting smooth lateral variations. In the case of 2-D or 3-D pronounced geometries, observational and numerical studies have shown that H/V curves exhibit peculiar shapes and that the H/V frequency generally overestimates 1-D theoretical resonance frequency. To investigate the capabilities of the H/V method in complex structures, a detailed comparison between measured and 3-D-simulated ambient vibrations was performed in the small-size lower Romanche valley (French Alps), which shows significant variations in geometry, downstream and upstream the Séchilienne basin. Analysing the H/V curve characteristics, two different wave propagation modes were identified along the valley. Relying on previous geophysical investigation, a power-law relationship was derived between the bedrock depth and the H/V peak frequency, which was used for building a 3-D model of the valley geometry. Simulated and experimental H/V curves were found to exhibit quite similar features in terms of curve shape and peak frequency values, validating the 3-D structure. This good agreement also evidenced two different propagation modes in the valley: 2-D resonance in the Séchilienne basin and 1-D resonance in the external parts. This study underlines the interest of H/V curves for investigating complex basin structures.
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.
2D Mica Crystal as Electret in Organic Field-Effect Transistors for Multistate Memory.
Zhang, Xiaotao; He, Yudong; Li, Rongjin; Dong, Huanli; Hu, Wenping
2016-05-01
Organic nonvolatile multistate storage devices based on organic field-effect transistors using mica as the 2D single-crystal electrets are developed. A4-paper-sized 2D mica crystals with flat surface are prepared successfully. Devices with mica electrets exhibit a typical memory effect and show ideal output curves on both the on and the off states.
The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis
Shaheen, Eman; Van Ongeval, Chantal; Zanca, Federica; Cockmartin, Lesley; Marshall, Nicholas; Jacobs, Jurgen; Young, Kenneth C.; Dance, David R.; Bosmans, Hilde
2011-12-15
Purpose: This work proposes a new method of building 3D models of microcalcification clusters and describes the validation of their realistic appearance when simulated into 2D digital mammograms and into breast tomosynthesis images. Methods: A micro-CT unit was used to scan 23 breast biopsy specimens of microcalcification clusters with malignant and benign characteristics and their 3D reconstructed datasets were segmented to obtain 3D models of microcalcification clusters. These models were then adjusted for the x-ray spectrum used and for the system resolution and simulated into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. Six radiologists were asked to distinguish between 40 real and 40 simulated clusters of microcalcifications in two separate studies on 2D mammography and tomosynthesis datasets. Receiver operating characteristic (ROC) analysis was used to test the ability of each observer to distinguish between simulated and real microcalcification clusters. The kappa statistic was applied to assess how often the individual simulated and real microcalcification clusters had received similar scores (''agreement'') on their realistic appearance in both modalities. This analysis was performed for all readers and for the real and the simulated group of microcalcification clusters separately. ''Poor'' agreement would reflect radiologists' confusion between simulated and real clusters, i.e., lesions not systematically evaluated in both modalities as either simulated or real, and would therefore be interpreted as a success of the present models. Results: The area under the ROC curve, averaged over the observers, was 0.55 (95% confidence interval [0.44, 0.66]) for the 2D study, and 0.46 (95% confidence interval [0.29, 0.64]) for the tomosynthesis study, indicating no statistically significant difference between real and simulated
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.
NASA Astrophysics Data System (ADS)
Mücke, Tanja A.; Wächter, Matthias; Milan, Patrick; Peinke, Joachim
2015-11-01
Based on the Langevin equation it has been proposed to obtain power curves for wind turbines from high frequency data of wind speed measurements u(t) and power output P (t). The two parts of the Langevin approach, power curve and drift field, give a comprehensive description of the conversion dynamic over the whole operating range of the wind turbine. The method deals with high frequent data instead of 10 min means. It is therefore possible to gain a reliable power curve already from a small amount of data per wind speed. Furthermore, the method is able to visualize multiple fixed points, which is e.g. characteristic for the transition from partial to full load or in case the conversion process deviates from the standard procedures. In order to gain a deeper knowledge it is essential that the method works not only for measured data but also for numerical wind turbine models and synthetic wind fields. Here, we characterize the dynamics of a detailed numerical wind turbine model and calculate the Langevin power curve for different data samplings. We show, how to get reliable results from synthetic data and verify the applicability of the method for field measurements with ultra-sonic, cup and Lidar measurements. The independence of the fixed points on site specific turbulence effects is also confirmed with the numerical model. Furthermore, we demonstrate the potential of the Langevin approach to detect failures in the conversion process and thus show the potential of the Langevin approach for a condition monitoring system.
Yoon, Jung Hyun; Shin, Hyun Joo; Kim, Eun-Kyung; Moon, Hee Jung; Roh, Yun Ho; Kwak, Jin Young
2015-11-01
The purpose of this study was to evaluate the usefulness of a quantitative vascular index in predicting thyroid malignancy. A total of 1309 thyroid nodules in 1257 patients (mean age: 50.2 y, range: 18-83 y) were included. The vascularity pattern and vascular index (VI) measured by quantification software for each nodule were obtained from 2-D power Doppler ultrasonography (US). Gray-scale US + vascularity pattern was compared with gray-scale US + VI with respect to diagnostic performance. Of the 1309 thyroid nodules, 927 (70.8%) were benign and 382 (29.2%) were malignant. The area under the receiver operating characteristics curve (Az) for gray-scale US (0.82) was significantly higher than that for US combined with vascularity pattern (0.77) or VI (0.70, all p < 0.001). Quantified VIs were higher in benign nodules, but did not improve the performance of 2-D US in diagnosing thyroid malignancy.
Role of cytochrome P450 2D6 genetic polymorphism in carvedilol hydroxylation in vitro
Wang, Zhe; Wang, Li; Xu, Ren-ai; Zhan, Yun-yun; Huang, Cheng-ke; Dai, Da-peng; Cai, Jian-ping; Hu, Guo-xin
2016-01-01
Cytochrome P450 2D6 (CYP2D6) is a highly polymorphic enzyme that catalyzes the metabolism of a great number of therapeutic drugs. Up to now, >100 allelic variants of CYP2D6 have been reported. Recently, we identified 22 novel variants in the Chinese population in these variants. The purpose of this study was to examine the enzymatic activity of the variants toward the CYP2D6 substrate carvedilol in vitro. The CYP2D6 proteins, including CYP2D6.1 (wild type), CYP2D6.2, CYP2D6.10, and 22 other novel CYP2D6 variants, were expressed from insect microsomes and incubated with carvedilol ranging from 1.0 μM to 50 μM at 37°C for 30 minutes. After termination, the carvedilol metabolites were extracted and detected using ultra-performance liquid chromatography tandem mass-spectrometry. Among the 24 CYP2D6 variants, CYP2D6.92 and CYP2D6.96 were catalytically inactive and the remaining 22 variants exhibited significantly decreased intrinsic clearance values (ranging from ~25% to 95%) compared with CYP2D6.1. The present data in vitro suggest that the newly found variants significantly reduced catalytic activities compared with CYP2D6.1. Given that CYP2D6 protein activities could affect carvedilol plasma levels, these findings are greatly relevant to personalized medicine. PMID:27354764
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.
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.
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
Bubin, Sergiy; Sharkey, Keeper L.; Adamowicz, Ludwik
2013-04-28
Very accurate variational nonrelativistic finite-nuclear-mass calculations employing all-electron explicitly correlated Gaussian basis functions are carried out for six Rydberg {sup 2}D states (1s{sup 2}nd, n= 6, Horizontal-Ellipsis , 11) of the {sup 7}Li and {sup 6}Li isotopes. The exponential parameters of the Gaussian functions are optimized using the variational method with the aid of the analytical energy gradient determined with respect to these parameters. The experimental results for the lower states (n= 3, Horizontal-Ellipsis , 6) and the calculated results for the higher states (n= 7, Horizontal-Ellipsis , 11) fitted with quantum-defect-like formulas are used to predict the energies of {sup 2}D 1s{sup 2}nd states for {sup 7}Li and {sup 6}Li with n up to 30.
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.
NASA Technical Reports Server (NTRS)
Morabito, D. D.; Skjerve, L.
1995-01-01
This article reports on the analysis of the Ka-band Antenna Performance Experiment tipping-curve data acquired at the DSS-13 research and development beam-waveguide (BWG) antenna. By measuring the operating system temperatures as the antenna is moved form zenith to low-elevation angles and fitting a model to the data, one can obtain information on how well the overall temperature model behaves at zenith and approximate the contribution due to the atmosphere. The atmospheric contribution estimated from the data can be expressed in the form of (1) atmospheric noise temperatures that can provide weather statistic information and be compared against those estimated from other methods and (2) the atmospheric loss factor used to refer efficiency measurements to zero atmosphere. This article reports on an analysis performed on a set of 68 8.4-GHz and 67 32-GHz tipping-curve data sets acquired between December 1993 and May 1995 and compares the results with those inferred from a surface model using input meteorological data and from water vapor radiometer (WVR) data. The general results are that, for a selected subset of tip curves, (1) the BWG tipping-curve atmospheric temperatures are in good agreement with those determined from WVR data (the average difference is 0.06 +/- 0.64 K at 32 GHz) and (2) the surface model average values are biased 3.6 K below those of the BWG and WVR at 32 GHz.
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
Peters, Heather L; Hou, Xiandeng; Jones, Bradley T
2003-09-01
A liquid chromatography system with an inductively coupled plasma detector is used to prepare a single calibration curve that is useful for multiple analytes. The detector monitors the atomic emission from carbon at 193.09 nm. Hence, the analytes need not exhibit appreciable molar absorptivity or native fluorescence. Since the carbon signal is independent of molecular structure, the sensitivities for different compounds are similar as long as nebulization efficiencies are comparable. In fact, with a suitable internal standard, no calibration curve is necessary. The capability of the system is demonstrated with a test mixture of nine amino acids separated with a C30 reversed-phase column and a 20 mM phosphate buffered mobile phase. The system provides a detection limit of 30 ng carbon. A multi-analyte calibration curve is prepared with 135 distinct measurements: each of nine analytes, at five different concentrations, repeated in triplicate. The average relative standard deviation for 27 measurements of different amino acids at a given concentration is 2.5%. Clearly, a single analyte will suffice for the calibration of all nine test compounds. Similarly, the internal standard method provides an average percent error of 2.0% for the determination of 45 different amino acid concentrations using only a single replicate for each sample.
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
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.
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.
Mason, Sarah; Van Hemelrijck, Mieke; Chandra, Ashish; Brown, Christian; Cahill, Declan
2016-01-01
Objective To document the learning curve for the laparoscopic radical prostatectomy (LRP) procedure and discuss the optimal usage of prospectively documented outcome data for reporting a surgeon’s performance. Materials and methods Using prospectively collected data from the first series of patients to undergo LRP by two surgeons in the same institution, linear and logistic regression multivariate analyses per 25 patients were carried out to graphically represent the surgical learning curve for operative time, blood loss, complications, length of stay (LOS), and positive margins. Surgeon A carried out 275 operations between 2003–2009; Surgeon B carried out 225 between 2008–2012. Results Learning curves showing continuous improvement of each of the above outcomes were demonstrated for both cohorts. For surgeon A, a plateau was observed for LOS and T2 positive margins after 100 and 150 surgeries respectively. No such plateau was observed for surgeon B. Conclusion On documenting these learning curves and discussion of the reporting methods used, we concluded that the most informative outcome measure, with the least potential observer bias was T2 positive margins. Whether as a single measure or in combination with others, this has potential for use as an objective outcome representative of improvement in a surgeon’s skill over time. PMID:27563346
ERIC Educational Resources Information Center
Rousseau, Ronald
1994-01-01
Discussion of informetric distributions shows that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibiting a Groos droop or a rising tail. The Kolmogorov-Smirnov test is used to test goodness of fit, and least-square fits are compared with Egghe's method. (Contains 53 references.) (LRW)
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.
A droplet-to-digital (D2D) microfluidic device for single cell assays.
Shih, Steve C C; Gach, Philip C; Sustarich, Jess; Simmons, Blake A; Adams, Paul D; Singh, Seema; Singh, Anup K
2015-01-01
We have developed a new hybrid droplet-to-digital microfluidic platform (D2D) that integrates droplet-in-channel microfluidics with digital microfluidics (DMF) for performing multi-step assays. This D2D platform combines the strengths of the two formats-droplets-in-channel for facile generation of droplets containing single cells, and DMF for on-demand manipulation of droplets including control of different droplet volumes (pL-μL), creation of a dilution series of ionic liquid (IL), and parallel single cell culturing and analysis for IL toxicity screening. This D2D device also allows for automated analysis that includes a feedback-controlled system for merging and splitting of droplets to add reagents, an integrated Peltier element for parallel cell culture at optimum temperature, and an impedance sensing mechanism to control the flow rate for droplet generation and preventing droplet evaporation. Droplet-in-channel is well-suited for encapsulation of single cells as it allows the careful manipulation of flow rates of aqueous phase containing cells and oil to optimize encapsulation. Once single cell containing droplets are generated, they are transferred to a DMF chip via a capillary where they are merged with droplets containing IL and cultured at 30 °C. The DMF chip, in addition to permitting cell culture and reagent (ionic liquid/salt) addition, also allows recovery of individual droplets for off-chip analysis such as further culturing and measurement of ethanol production. The D2D chip was used to evaluate the effect of IL/salt type (four types: NaOAc, NaCl, [C2mim] [OAc], [C2mim] [Cl]) and concentration (four concentrations: 0, 37.5, 75, 150 mM) on the growth kinetics and ethanol production of yeast and as expected, increasing IL concentration led to lower biomass and ethanol production. Specifically, [C2mim] [OAc] had inhibitory effects on yeast growth at concentrations 75 and 150 mM and significantly reduced their ethanol production compared to cells grown
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.
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.
Gous, R M; Cherry, P
2004-08-01
1. A total of 4000 Ross broiler breeders were reared to a 20-week target body weight of 1.55, 2.16 (standard), 2.50 or 2.84 kg, using either a convex or concave growth curve. Each treatment group was either exposed to a conventional broiler breeder lighting regimen, with a series of weekly one-hour increments in photoperiod from 8h at 19 weeks to a 16-h maximum, or maintained from 4d on a 17-h photoperiod. 2. Each 100 g increment in body weight at 20 weeks was associated with a significant increase of 0.55 kg in cumulative food intake, and a 1.5-d advance in sexual maturity. However, leaner body weights at 20 weeks resulted in smaller body weight gains between 20 and 60 weeks (-2.4 g/d/kg body weight at 20 weeks), and an increased production of double-yolked eggs. Neither egg production nor mean egg weight was affected by 20-week body weight. 3. Birds fed to produce more rapid early growth had higher feed intakes to 20 weeks, but reached sexual maturity 7 d later than birds permitted accelerated growth from 15 weeks. Growth curve did not influence body weight gain in lay, egg production or mean egg weight. 4. Birds maintained on 17-h photoperiods reached sexual maturity 27 d later, produced 7 fewer eggs to 60 weeks, and had a mean egg weight 1.2 g heavier than birds photostimulated at 19 weeks. Lighting treatment did not affect food intake to 20 weeks, the proportion of double-yolked eggs or body weight gain between 20 and 60 weeks. 5. Birds fed to have a faster growth early in the rearing phase and maintained on 17-h photoperiods produced 11 fewer eggs than those fed to have accelerated growth at the end of the rearing phase, yet there was only one egg difference between the growth-curve groups for the conventionally lighted birds, which was not significant. 6. The earlier sexual maturity of the conventionally lighted birds compared with those maintained on 17-h photoperiods either indicates that broiler breeders require an increment in photoperiod to stimulate
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.
NASA Technical Reports Server (NTRS)
Alston, D. W.
1981-01-01
The considered research had the objective to design a statistical model that could perform an error analysis of curve fits of wind tunnel test data using analysis of variance and regression analysis techniques. Four related subproblems were defined, and by solving each of these a solution to the general research problem was obtained. The capabilities of the evolved true statistical model are considered. The least squares fit is used to determine the nature of the force, moment, and pressure data. The order of the curve fit is increased in order to delete the quadratic effect in the residuals. The analysis of variance is used to determine the magnitude and effect of the error factor associated with the experimental 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.
2D image classification for 3D anatomy localization: employing deep convolutional neural networks
NASA Astrophysics Data System (ADS)
de Vos, Bob D.; Wolterink, Jelmer M.; de Jong, Pim A.; Viergever, Max A.; Išgum, Ivana
2016-03-01
Localization of anatomical regions of interest (ROIs) is a preprocessing step in many medical image analysis tasks. While trivial for humans, it is complex for automatic methods. Classic machine learning approaches require the challenge of hand crafting features to describe differences between ROIs and background. Deep convolutional neural networks (CNNs) alleviate this by automatically finding hierarchical feature representations from raw images. We employ this trait to detect anatomical ROIs in 2D image slices in order to localize them in 3D. In 100 low-dose non-contrast enhanced non-ECG synchronized screening chest CT scans, a reference standard was defined by manually delineating rectangular bounding boxes around three anatomical ROIs -- heart, aortic arch, and descending aorta. Every anatomical ROI was automatically identified using a combination of three CNNs, each analyzing one orthogonal image plane. While single CNNs predicted presence or absence of a specific ROI in the given plane, the combination of their results provided a 3D bounding box around it. Classification performance of each CNN, expressed in area under the receiver operating characteristic curve, was >=0.988. Additionally, the performance of ROI localization was evaluated. Median Dice scores for automatically determined bounding boxes around the heart, aortic arch, and descending aorta were 0.89, 0.70, and 0.85 respectively. The results demonstrate that accurate automatic 3D localization of anatomical structures by CNN-based 2D image classification is feasible.
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.
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.
On the sensitivity of the 2D electromagnetic invisibility cloak
NASA Astrophysics Data System (ADS)
Kaproulias, S.; Sigalas, M. M.
2012-10-01
A computational study of the sensitivity of the two dimensional (2D) electromagnetic invisibility cloaks is performed with the finite element method. A circular metallic object is covered with the cloak and the effects of absorption, gain and disorder are examined. Also the effect of covering the cloak with a thin dielectric layer is studied.
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.
Influence of lattice defects on the ferromagnetic resonance behaviour of 2D magnonic crystals
Manzin, Alessandra; Barrera, Gabriele; Celegato, Federica; Coïsson, Marco; Tiberto, Paola
2016-01-01
This paper studies, from a modelling point of view, the influence of randomly distributed lattice defects (non-patterned areas and variable hole size) on the ferromagnetic resonance behaviour and spin wave mode profiles of 2D magnonic crystals based on Ni80Fe20 antidot arrays with hexagonal lattice. A reference sample is first defined via the comparison of experimental and simulated hysteresis loops and magnetoresistive curves of patterned films, prepared by self-assembly of polystyrene nanospheres. Second, a parametric analysis of the dynamic response is performed, investigating how edge, quasi-uniform and localized modes are affected by alterations of the lattice geometry and bias field amplitude. Finally, some results about the possible use of magnetic antidot arrays in frequency-based sensors for magnetic bead detection are presented, highlighting the need for an accurate control of microstructural features. PMID:26911336
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.
2D nanostructures for water purification: graphene and beyond.
Dervin, Saoirse; Dionysiou, Dionysios D; Pillai, Suresh C
2016-08-18
Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials. Recent progress in the development of nanoporous graphene based materials has generated enormous potential for water purification technologies. Progress in the development of nanoporous graphene and graphene oxide (GO) membranes, the mechanism of graphene molecular sieve action, structural design, hydrophilic nature, mechanical strength and antifouling properties and the principal challenges associated with nanopore generation are discussed in detail. Subsequently, the recent applications and performance of newly developed 2D materials such as 2D boron nitride (BN) nanosheets, graphyne, molybdenum disulfide (MoS2), tungsten chalcogenides (WS2) and titanium carbide (Ti3C2Tx) are highlighted. In addition, the challenges affecting 2D nanostructures for water purification are highlighted and their applications in the water purification industry are discussed. Though only a few 2D materials have been explored so far for water treatment applications, this emerging field of research is set to attract a great deal of attention in the near future.
Ultrafast 2D NMR: an emerging tool in analytical spectroscopy.
Giraudeau, Patrick; Frydman, Lucio
2014-01-01
Two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago, a so-called ultrafast (UF) approach was proposed, capable of delivering arbitrary 2D NMR spectra involving any kind of homo- or heteronuclear correlation, in a single scan. During the intervening years, the performance of this subsecond 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool experiencing an expanded scope of applications. This review summarizes the principles and main developments that have contributed to the success of this approach and focuses on applications that have been recently demonstrated in various areas of analytical chemistry--from the real-time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications. PMID:25014342
2D nanostructures for water purification: graphene and beyond.
Dervin, Saoirse; Dionysiou, Dionysios D; Pillai, Suresh C
2016-08-18
Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials. Recent progress in the development of nanoporous graphene based materials has generated enormous potential for water purification technologies. Progress in the development of nanoporous graphene and graphene oxide (GO) membranes, the mechanism of graphene molecular sieve action, structural design, hydrophilic nature, mechanical strength and antifouling properties and the principal challenges associated with nanopore generation are discussed in detail. Subsequently, the recent applications and performance of newly developed 2D materials such as 2D boron nitride (BN) nanosheets, graphyne, molybdenum disulfide (MoS2), tungsten chalcogenides (WS2) and titanium carbide (Ti3C2Tx) are highlighted. In addition, the challenges affecting 2D nanostructures for water purification are highlighted and their applications in the water purification industry are discussed. Though only a few 2D materials have been explored so far for water treatment applications, this emerging field of research is set to attract a great deal of attention in the near future. PMID:27506268
Graphene based 2D-materials for supercapacitors
NASA Astrophysics Data System (ADS)
Palaniselvam, Thangavelu; Baek, Jong-Beom
2015-09-01
Ever-increasing energy demands and the depletion of fossil fuels are compelling humanity toward the development of suitable electrochemical energy conversion and storage devices to attain a more sustainable society with adequate renewable energy and zero environmental pollution. In this regard, supercapacitors are being contemplated as potential energy storage devices to afford cleaner, environmentally friendly energy. Recently, a great deal of attention has been paid to two-dimensional (2D) nanomaterials, including 2D graphene and its inorganic analogues (transition metal double layer hydroxides, chalcogenides, etc), as potential electrodes for the development of supercapacitors with high electrochemical performance. This review provides an overview of the recent progress in using these graphene-based 2D materials as potential electrodes for supercapacitors. In addition, future research trends including notable challenges and opportunities are also discussed.
NASA Technical Reports Server (NTRS)
Huang, Norden E. (Inventor)
2002-01-01
A computer implemented physical signal analysis method includes four basic steps and the associated presentation techniques of the results. The first step is a computer implemented Empirical Mode Decomposition that extracts a collection of Intrinsic Mode Functions (IMF) from nonlinear, nonstationary physical signals. The decomposition is based on the direct extraction of the energy associated with various intrinsic time scales in the physical signal. Expressed in the IMF's, they have well-behaved Hilbert Transforms from which instantaneous frequencies can be calculated. The second step is the Hilbert Transform which produces a Hilbert Spectrum. Thus, the invention can localize any event on the time as well as the frequency axis. The decomposition can also be viewed as an expansion of the data in terms of the IMF's. Then, these IMF's, based on and derived from the data, can serve as the basis of that expansion. The local energy and the instantaneous frequency derived from the IMF's through the Hilbert transform give a full energy-frequency-time distribution of the data which is designated as the Hilbert Spectrum. The third step filters the physical signal by combining a subset of the IMFs. In the fourth step, a curve may be fitted to the filtered signal which may not have been possible with the original, unfiltered signal.
NASA Technical Reports Server (NTRS)
Huang, Norden E. (Inventor)
2004-01-01
A computer implemented physical signal analysis method includes four basic steps and the associated presentation techniques of the results. The first step is a computer implemented Empirical Mode Decomposition that extracts a collection of Intrinsic Mode Functions (IMF) from nonlinear, nonstationary physical signals. The decomposition is based on the direct extraction of the energy associated with various intrinsic time scales in the physical signal. Expressed in the IMF's, they have well-behaved Hilbert Transforms from which instantaneous frequencies can be calculated. The second step is the Hilbert Transform which produces a Hilbert Spectrum. Thus, the invention can localize any event on the time as well as the frequency axis. The decomposition can also be viewed as an expansion of the data in terms of the IMF's. Then, these IMF's, based on and derived from the data, can serve as the basis of that expansion. The local energy and the instantaneous frequency derived from the IMF's through the Hilbert transform give a full energy-frequency-time distribution of the data which is designated as the Hilbert Spectrum. The third step filters the physical signal by combining a subset of the IMFs. In the fourth step, a curve may be fitted to the filtered signal which may not have been possible with the original, unfiltered signal.
Section Curve Reconstruction and Mean-Camber Curve Extraction of a Point-Sampled Blade Surface
Li, Wen-long; Xie, He; Li, Qi-dong; Zhou, Li-ping; Yin, Zhou-ping
2014-01-01
The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization. PMID:25551467
Section curve reconstruction and mean-camber curve extraction of a point-sampled blade surface.
Li, Wen-long; Xie, He; Li, Qi-dong; Zhou, Li-ping; Yin, Zhou-ping
2014-01-01
The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization.
Section curve reconstruction and mean-camber curve extraction of a point-sampled blade surface.
Li, Wen-long; Xie, He; Li, Qi-dong; Zhou, Li-ping; Yin, Zhou-ping
2014-01-01
The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization. PMID:25551467
Rowley-Neale, Samuel J; Fearn, Jamie M; Brownson, Dale A C; Smith, Graham C; Ji, Xiaobo; Banks, Craig E
2016-08-21
Two-dimensional molybdenum disulphide nanosheets (2D-MoS2) have proven to be an effective electrocatalyst, with particular attention being focused on their use towards increasing the efficiency of the reactions associated with hydrogen fuel cells. Whilst the majority of research has focused on the Hydrogen Evolution Reaction (HER), herein we explore the use of 2D-MoS2 as a potential electrocatalyst for the much less researched Oxygen Reduction Reaction (ORR). We stray from literature conventions and perform experiments in 0.1 M H2SO4 acidic electrolyte for the first time, evaluating the electrochemical performance of the ORR with 2D-MoS2 electrically wired/immobilised upon several carbon based electrodes (namely; Boron Doped Diamond (BDD), Edge Plane Pyrolytic Graphite (EPPG), Glassy Carbon (GC) and Screen-Printed Electrodes (SPE)) whilst exploring a range of 2D-MoS2 coverages/masses. Consequently, the findings of this study are highly applicable to real world fuel cell applications. We show that significant improvements in ORR activity can be achieved through the careful selection of the underlying/supporting carbon materials that electrically wire the 2D-MoS2 and utilisation of an optimal mass of 2D-MoS2. The ORR onset is observed to be reduced to ca. +0.10 V for EPPG, GC and SPEs at 2D-MoS2 (1524 ng cm(-2) modification), which is far closer to Pt at +0.46 V compared to bare/unmodified EPPG, GC and SPE counterparts. This report is the first to demonstrate such beneficial electrochemical responses in acidic conditions using a 2D-MoS2 based electrocatalyst material on a carbon-based substrate (SPEs in this case). Investigation of the beneficial reaction mechanism reveals the ORR to occur via a 4 electron process in specific conditions; elsewhere a 2 electron process is observed. This work offers valuable insights for those wishing to design, fabricate and/or electrochemically test 2D-nanosheet materials towards the ORR. PMID:27448174
Rowley-Neale, Samuel J; Fearn, Jamie M; Brownson, Dale A C; Smith, Graham C; Ji, Xiaobo; Banks, Craig E
2016-08-21
Two-dimensional molybdenum disulphide nanosheets (2D-MoS2) have proven to be an effective electrocatalyst, with particular attention being focused on their use towards increasing the efficiency of the reactions associated with hydrogen fuel cells. Whilst the majority of research has focused on the Hydrogen Evolution Reaction (HER), herein we explore the use of 2D-MoS2 as a potential electrocatalyst for the much less researched Oxygen Reduction Reaction (ORR). We stray from literature conventions and perform experiments in 0.1 M H2SO4 acidic electrolyte for the first time, evaluating the electrochemical performance of the ORR with 2D-MoS2 electrically wired/immobilised upon several carbon based electrodes (namely; Boron Doped Diamond (BDD), Edge Plane Pyrolytic Graphite (EPPG), Glassy Carbon (GC) and Screen-Printed Electrodes (SPE)) whilst exploring a range of 2D-MoS2 coverages/masses. Consequently, the findings of this study are highly applicable to real world fuel cell applications. We show that significant improvements in ORR activity can be achieved through the careful selection of the underlying/supporting carbon materials that electrically wire the 2D-MoS2 and utilisation of an optimal mass of 2D-MoS2. The ORR onset is observed to be reduced to ca. +0.10 V for EPPG, GC and SPEs at 2D-MoS2 (1524 ng cm(-2) modification), which is far closer to Pt at +0.46 V compared to bare/unmodified EPPG, GC and SPE counterparts. This report is the first to demonstrate such beneficial electrochemical responses in acidic conditions using a 2D-MoS2 based electrocatalyst material on a carbon-based substrate (SPEs in this case). Investigation of the beneficial reaction mechanism reveals the ORR to occur via a 4 electron process in specific conditions; elsewhere a 2 electron process is observed. This work offers valuable insights for those wishing to design, fabricate and/or electrochemically test 2D-nanosheet materials towards the ORR.
Tarud, F; Aybar, M; Pizarro, G; Cienfuegos, R; Pastén, P
2010-08-01
Enhancing the performance of clarifiers requires a thorough understanding of their hydraulics. Fluorescence spectroscopy and acoustic doppler velocimeter (ADV) profiling generally have been used separately to evaluate secondary settlers. We propose that simultaneous use of these techniques is needed to obtain a more reliable and useful evaluation. Experiments were performed on laboratory- and full-scale clarifiers. Factors affecting Fluorescein and Rhodamine 6G properties were identified. Underestimations up to 500% in fluorescence intensities may be derived from differential fluorescence quenching by oxygen. A careful control and interpretation of fluorescent dye experiments is needed to minimize artifacts in real settings. While flow-curve tests constructed under controlled conditions provided a more accurate overall quantitative estimation of the hydraulic performance, ADV velocity and turbulence profiling provided a detailed spatial understanding of flow patterns that was used to troubleshoot and fix the causes of hydraulic short-circuits.
Tarud, F; Aybar, M; Pizarro, G; Cienfuegos, R; Pastén, P
2010-08-01
Enhancing the performance of clarifiers requires a thorough understanding of their hydraulics. Fluorescence spectroscopy and acoustic doppler velocimeter (ADV) profiling generally have been used separately to evaluate secondary settlers. We propose that simultaneous use of these techniques is needed to obtain a more reliable and useful evaluation. Experiments were performed on laboratory- and full-scale clarifiers. Factors affecting Fluorescein and Rhodamine 6G properties were identified. Underestimations up to 500% in fluorescence intensities may be derived from differential fluorescence quenching by oxygen. A careful control and interpretation of fluorescent dye experiments is needed to minimize artifacts in real settings. While flow-curve tests constructed under controlled conditions provided a more accurate overall quantitative estimation of the hydraulic performance, ADV velocity and turbulence profiling provided a detailed spatial understanding of flow patterns that was used to troubleshoot and fix the causes of hydraulic short-circuits. PMID:20853746
2D and 3D Traveling Salesman Problem
ERIC Educational Resources Information Center
Haxhimusa, Yll; Carpenter, Edward; Catrambone, Joseph; Foldes, David; Stefanov, Emil; Arns, Laura; Pizlo, Zygmunt
2011-01-01
When a two-dimensional (2D) traveling salesman problem (TSP) is presented on a computer screen, human subjects can produce near-optimal tours in linear time. In this study we tested human performance on a real and virtual floor, as well as in a three-dimensional (3D) virtual space. Human performance on the real floor is as good as that on a…
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
Sase, Sunetra; Khan, Deeba; Sialana, Fernando; Höger, Harald; Russo-Schlaff, Nina; Lubec, Gert
2012-12-01
Modafinil has been shown to modify behavioural and cognitive functions and to effect several brain receptors. Effects, however, were not observed at the receptor protein complex level and it was therefore the aim of the study to train mice in the multiple T-Maze (MTM) as a paradigm for spatial memory and to determine paralleling brain receptor complex levels. Sixty C57BL/6J mice were used in the study and divided into four groups (trained drug injected; trained vehicle injected; yoked drug injected; yoked vehicle injected). Animals obtained training for 4 days and were killed 6 h following the last training session on day 4. Hippocampi were dissected from the brain, membrane fractions were prepared by ultracentrifugation and were run on blue-native gels and immunoblotted with antibodies against major brain receptors. Modafinil treatment led to decreased latency and increased average speed, but not to changes in pathlength and number of correct decisions in the MTM. Drug effects were modifying receptor complexes of GluR1, GluR2, D2 and NR1. Training effects on receptor complex levels were observed for GluR3, D1 and nicotinic acetylcholine receptor alpha 7 (Nic7). GluR1 levels were correlating with GluR2 and D1 levels were correlating with D2 and NR1. Involvement of the glutamatergic, NMDA, dopaminergic and nicotinergic system in modafinil and memory training were herein described for the first time. A brain receptor complex pattern was revealed showing the concerted action following modafinil treatment.
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.
Creative Tiling: A Story of 1000-and-1 Curves
ERIC Educational Resources Information Center
Al-Darwish, Nasir
2012-01-01
We describe a procedure that utilizes symmetric curves for building artistic tiles. One particular curve was found to mesh nicely with hundreds other curves, resulting in eye-catching tiling designs. The results of our work serve as a good example of using ideas from 2-D graphics and algorithms in a practical web-based application.
NASA Astrophysics Data System (ADS)
Rowley-Neale, Samuel J.; Fearn, Jamie M.; Brownson, Dale A. C.; Smith, Graham C.; Ji, Xiaobo; Banks, Craig E.
2016-08-01
Two-dimensional molybdenum disulphide nanosheets (2D-MoS2) have proven to be an effective electrocatalyst, with particular attention being focused on their use towards increasing the efficiency of the reactions associated with hydrogen fuel cells. Whilst the majority of research has focused on the Hydrogen Evolution Reaction (HER), herein we explore the use of 2D-MoS2 as a potential electrocatalyst for the much less researched Oxygen Reduction Reaction (ORR). We stray from literature conventions and perform experiments in 0.1 M H2SO4 acidic electrolyte for the first time, evaluating the electrochemical performance of the ORR with 2D-MoS2 electrically wired/immobilised upon several carbon based electrodes (namely; Boron Doped Diamond (BDD), Edge Plane Pyrolytic Graphite (EPPG), Glassy Carbon (GC) and Screen-Printed Electrodes (SPE)) whilst exploring a range of 2D-MoS2 coverages/masses. Consequently, the findings of this study are highly applicable to real world fuel cell applications. We show that significant improvements in ORR activity can be achieved through the careful selection of the underlying/supporting carbon materials that electrically wire the 2D-MoS2 and utilisation of an optimal mass of 2D-MoS2. The ORR onset is observed to be reduced to ca. +0.10 V for EPPG, GC and SPEs at 2D-MoS2 (1524 ng cm-2 modification), which is far closer to Pt at +0.46 V compared to bare/unmodified EPPG, GC and SPE counterparts. This report is the first to demonstrate such beneficial electrochemical responses in acidic conditions using a 2D-MoS2 based electrocatalyst material on a carbon-based substrate (SPEs in this case). Investigation of the beneficial reaction mechanism reveals the ORR to occur via a 4 electron process in specific conditions; elsewhere a 2 electron process is observed. This work offers valuable insights for those wishing to design, fabricate and/or electrochemically test 2D-nanosheet materials towards the ORR.Two-dimensional molybdenum disulphide nanosheets
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
Straightening Out Learning Curves
ERIC Educational Resources Information Center
Corlett, E. N.; Morecombe, V. J.
1970-01-01
The basic mathematical theory behind learning curves is explained, together with implications for clerical and industrial training, evaluation of skill development, and prediction of future performance. Brief studies of textile worker and typist training are presented to illustrate such concepts as the reduction fraction (a consistent decrease in…
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.
Taghavi Moghaddam, Pooria; Pipelzadeh, Mohammad Reza; Nesioonpour, Sholeh; Saki, Nader; Rezaee, Saeed
2014-01-01
Purpose: The aim of this study was to select the best calibration model for determination of propofol plasma concentration by high-performance liquid chromatography method. Methods: Determination of propofol in plasma after deproteinization with acetonitrile containing thymol (as internal standard) was carried out on a C18 column with a mixture of acetonitrile and trifluoroacetic acid 0.1% (60:40) as mobile phase which delivered at the flow rate of 1.2 mL/minute . Fluorescence detection was done at the excitation and emission wavelengths of 276 and 310 nm, respectively. After fitting different equations to the calibration data using weighted regression, the adequacy of models were assessed by lack-of-fit test, significance of all model parameters, adjusted coefficient of determination (R2adjusted) and by measuring the predictive performance with median relative prediction error and median absolute relative prediction error of the validation data set. Results: The best model was a linear equation without intercept with median relative prediction error and median absolute relative prediction error of 4.0 and 9.4%, respectively in the range of 10-5000 ng/mL. The method showed good accuracy and precision. Conclusion: The presented statistical framework could be used to choose the best model for heteroscedastic calibration data for analytes like propofol with wide range of expected concentration. PMID:25436190
Mangan, Mehmet Serhat; Atalay, Eray; Arıcı, Ceyhun; Tuncer, İbrahim; Bilgeç, Mustafa Değer
2016-01-01
Objectives: To compare the differences in intraoperative complications rates by the number of resident-performed sequential phacoemulsification surgeries. Materials and Methods: Preoperative and postoperative ophthalmological examination records and intraoperative data of 180 eyes of 140 patients who underwent cataract surgery by two residents between November 2009 and February 2012 were analyzed retrospectively. The data of 180 eyes were separated into 3 groups based on the number of operations performed: Group A (first 1-60 eyes), group B (61-120 eyes) and group C (last 121-180 eyes). The number of direct supervisor interventions and the rates of different types of complications were compared between the three groups. Results: The number of direct supervisor interventions was 45, 35 and 19 in group A, B and C, respectively. The number of complications anterior to the iris plane was 3, 4 and 12 in group A, B and C, respectively. The difference in the rate of complications between group B and C was statistically significant (p=0.029). The number of complications posterior to the iris plane was 6, 14 and 3 in group A, B and C, respectively. The difference in the rate of complications between the groups was statistically significant (p=0.042, p=0.004). Conclusion: This study provides insight into which types of complications might arise during the phacoemulsification training period. The trends in the rates of different complication types in clinics may be analyzed, and this analysis may be used to improve and modify phacoemulsification training programmes according to the needs of residents. PMID:27800250
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.
Casellas, J M; Tome, G; Exeni, R; Grimoldi, I; Goldberg, M; Farinati, A E
1993-04-01
Since resistance to several oral antimicrobials useful for the treatment of pediatric urinary tract infections (UTI) is overwhelming in Argentina, an in vitro investigation was performed testing 400 isolates obtained from urines of children suffering UTI's, 200 collected in 1990 and 200 in 1991. Their susceptibility against oral antimicrobials marketed in Argentina and appropriate for the treatment of UTI was determined by the agar dilution methods. An increase of the resistance to aminopenicillin combined with beta-lactamase inhibitors and to fluoroquinolones was observed comparing the two periods. Cefpodoxime (CPD), cefixime and fluoroquinolones except norfloxacin were the sole oral antimicrobials showing in vitro activity at the 90 per cent level. Unfortunately fluoroquinolones are not yet approved for pediatric use. Consequently we realized an in vitro and in vivo pharmacokinetic study in order to determine CPD activity against E. coli isolated in UTI cases. Five children (6-10 y) showing E. coli UTI infections received 10 mg/kg/d CPD in a single oral daily dose and were treated up to 10 days, 3 had lower UTI and 2 upper UTI. All patients were clinical and bacteriologically cured. Cultures obtained up to 4 weeks after treatment were negative. CPD serum levels at 2 hours after the first dose of treatment showed a median of 2.7 mg/l (2.3-3.4 range). Bactericidal serum titers at the same time against the patients own strain and an E. coli TEM-1 hyperproducer strain (MIC 4,096 mg/l for ampicillin and 0.5 mg/l for CPD) showed a median value of 1/8 against patients strains and 1/2 against the THP strain.(ABSTRACT TRUNCATED AT 250 WORDS)
Large Deformation Diffeomorphic Metric Curve Mapping
Glaunès, Joan; Miller, Michael I.; Younes, Laurent
2010-01-01
We present a matching criterion for curves and integrate it into the large deformation diffeomorphic metric mapping (LDDMM) scheme for computing an optimal transformation between two curves embedded in Euclidean space ℝd. Curves are first represented as vector-valued measures, which incorporate both location and the first order geometric structure of the curves. Then, a Hilbert space structure is imposed on the measures to build the norm for quantifying the closeness between two curves. We describe a discretized version of this, in which discrete sequences of points along the curve are represented by vector-valued functionals. This gives a convenient and practical way to define a matching functional for curves. We derive and implement the curve matching in the large deformation framework and demonstrate mapping results of curves in ℝ2 and ℝ3. Behaviors of the curve mapping are discussed using 2D curves. The applications to shape classification is shown and experiments with 3D curves extracted from brain cortical surfaces are presented. PMID:20419045
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.
CBEAM. 2-D: a two-dimensional beam field code
Dreyer, K.A.
1985-05-01
CBEAM.2-D is a two-dimensional solution of Maxwell's equations for the case of an electron beam propagating through an air medium. Solutions are performed in the beam-retarded time frame. Conductivity is calculated self-consistently with field equations, allowing sophisticated dependence of plasma parameters to be handled. A unique feature of the code is that it is implemented on an IBM PC microcomputer in the BASIC language. Consequently, it should be available to a wide audience.
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.
Calibration of hydraulic models: effects of rating-curve uncertainty
NASA Astrophysics Data System (ADS)
Domeneghetti, Alessio; Castellarin, Attilio; Brath, Armando
2010-05-01
This research focuses on the uncertainty of rating-curves and how this uncertainty propagates to Manning's roughness coefficient during the calibration of numerical hydraulic models. Rating-curves, relating stage and flow discharge, are traditionally used for describing boundary conditions. The uncertainty associated with rating-curves is often neglected, and generally considered to be less important than other factors (see e.g., Di Baldassarre and Montanari, HESS, 2009). We performed a series of simulation experiments aimed at: (1) quantitatively assessing the uncertainty of the curves; (2) investigating its effects on the calibration of Manning's roughness coefficient. We used a quasi-bidimensional (quasi-2D) model of the middle-lower reach of the River Po (Northern Italy) to simulate 10 different historical flood events for the hydrometric river cross-section located in Cremona. Using the simulated data, we mimicked 15 measurement campaigns for each flood event and we corrupted the discharge data values according to the indications on measurement campaigns and errors reported in the literature (i.e., EU. ISO EN 748, 1997). We then constructed the 90% confidence interval for the synthetic curves. Then, we performed an additional set of model runs downstream of the Cremona's cross-section to assess how the uncertainty of rating curves affects the estimated Manning coefficients during the calibration phase. The results of the study show that the variation of Manning's roughness coefficient resulting from the rating-curve uncertainty is significant. This variation is analysed and discussed relative to the variability of Manning's coefficient reported in the literature for different channel conditions characterising lower reaches of large natural streams.
MAZE. Generates 2D Input for DYNA NIKE & TOPAZ
Hallquist, J.O.
1992-02-10
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
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.
MAZE. Generates 2D Input for DYNA, NIKE & TOPAZ
Hallquist, J.O.
1992-02-12
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
MAZE. Generates 2D Input for DYNA NIKE & TOPAZ
Hallquist, J.O.
1992-02-24
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
MAZE. Generates 2D Input for DYNA, NIKE, & TOPAZ
Hallquist, J.O.
1992-02-10
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
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
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
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
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.
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
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
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.
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.
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.
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.
ERIC Educational Resources Information Center
Yates, Robert C.
This volume, a reprinting of a classic first published in 1952, presents detailed discussions of 26 curves or families of curves, and 17 analytic systems of curves. For each curve the author provides a historical note, a sketch or sketches, a description of the curve, a discussion of pertinent facts, and a bibliography. Depending upon the curve,…
2-D Magnetohydrodynamic Modeling of A Pulsed Plasma Thruster
NASA Technical Reports Server (NTRS)
Thio, Y. C. Francis; Cassibry, J. T.; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)
2002-01-01
Experiments are being performed on the NASA Marshall Space Flight Center (MSFC) MK-1 pulsed plasma thruster. Data produced from the experiments provide an opportunity to further understand the plasma dynamics in these thrusters via detailed computational modeling. The detailed and accurate understanding of the plasma dynamics in these devices holds the key towards extending their capabilities in a number of applications, including their applications as high power (greater than 1 MW) thrusters, and their use for producing high-velocity, uniform plasma jets for experimental purposes. For this study, the 2-D MHD modeling code, MACH2, is used to provide detailed interpretation of the experimental data. At the same time, a 0-D physics model of the plasma initial phase is developed to guide our 2-D modeling studies.
Critical Dynamics in Quenched 2D Atomic Gases
NASA Astrophysics Data System (ADS)
Larcher, F.; Dalfovo, F.; Proukakis, N. P.
2016-05-01
Non-equilibrium dynamics across phase transitions is a subject of intense investigations in diverse physical systems. One of the key issues concerns the validity of the Kibble-Zurek (KZ) scaling law for spontaneous defect creation. The KZ mechanism has been recently studied in cold atoms experiments. Interesting open questions arise in the case of 2D systems, due to the distinct nature of the Berezinskii-Kosterlitz-Thouless (BKT) transition. Our studies rely on the stochastic Gross-Pitaevskii equation. We perform systematic numerical simulations of the spontaneous emergence and subsequent dynamics of vortices in a uniform 2D Bose gas, which is quenched across the BKT phase transition in a controlled manner, focusing on dynamical scaling and KZ-type effects. By varying the transverse confinement, we also look at the extent to which such features can be seen in current experiments. Financial support from EPSRC and Provincia Autonoma di Trento.
Linkage studies for T2D in Chop and C/EBPbeta chromosomal regions in Italians.
Gragnoli, Claudia; Pierpaoli, Laura; Piumelli, Nunzia; Chiaramonte, Francesco
2007-11-01
The genes causing type 2 diabetes (T2D), a complex heterogeneous disorder, differ and/or overlap in various populations. Among others there are two loci in linkage to T2D, the chromosomes 20q12-13.1 and 12q15. These two regions harbor two genes, C/EBPbeta and CHOP, which are excellent candidate genes for T2D. In fact, C/EBPbeta protein cooperates with HNF4alpha (MODY1, monogenic form of diabetes) and 1alpha (MODY3, monogenic form of diabetes). C/EBPbeta mediates suppression of insulin gene transcription in hyperglycemia and may contribute to insulin-resistance. It interacts in a complex pathway with the CHOP protein. CHOP may play a role in altered beta-cell glucose metabolism, in beta-cell apoptosis, and in lack of beta-cell replication. Thus, both C/EBPbeta and CHOP genes may independently and interactively contribute to T2D. The chromosomal regions targeting C/EBPbeta and CHOP genes have never been previously explored in T2D. We planned to identify their potential contribution to T2D in Italians. We have genotyped a group of affected siblings/families with both late- and early-onset T2D around the C/EBPbeta and the CHOP genes. We have performed non-parametric linkage analysis in the total T2D group, in the late-onset and the early-onset group, separately. We have identified a suggestive linkage to T2D in the CHOP gene locus in the early-onset T2D group (P = 0.04). We identified the linkage to T2D in the chromosome 12q15 region in the early-onset T2D families and specifically target the CHOP gene. Our next step will be the identification of CHOP gene variants, which may contribute to the linkage to T2D in Italians. PMID:17620318
Surface wave phase velocities from 2-D surface wave tomography studies in the Anatolian plate
NASA Astrophysics Data System (ADS)
Arif Kutlu, Yusuf; Erduran, Murat; Çakır, Özcan; Vinnik, Lev; Kosarev, Grigoriy; Oreshin, Sergey
2014-05-01
We study the Rayleigh and Love surface wave fundamental mode propagation beneath the Anatolian plate. To examine the inter-station phase velocities a two-station method is used along with the Multiple Filter Technique (MFT) in the Computer Programs in Seismology (Herrmann and Ammon, 2004). The near-station waveform is deconvolved from the far-station waveform removing the propagation effects between the source and the station. This method requires that the near and far stations are aligned with the epicentre on a great circle path. The azimuthal difference of the earthquake to the two-stations and the azimuthal difference between the earthquake and the station are restricted to be smaller than 5o. We selected 3378 teleseismic events (Mw >= 5.7) recorded by 394 broadband local stations with high signal-to-noise ratio within the years 1999-2013. Corrected for the instrument response suitable seismogram pairs are analyzed with the two-station method yielding a collection of phase velocity curves in various period ranges (mainly in the range 25-185 sec). Diffraction from lateral heterogeneities, multipathing, interference of Rayleigh and Love waves can alter the dispersion measurements. In order to obtain quality measurements, we select only smooth portions of the phase velocity curves, remove outliers and average over many measurements. We discard these average phase velocity curves suspected of suffering from phase wrapping errors by comparing them with a reference Earth model (IASP91 by Kennett and Engdahl, 1991). The outlined analysis procedure yields 3035 Rayleigh and 1637 Love individual phase velocity curves. To obtain Rayleigh and Love wave travel times for a given region we performed 2-D tomographic inversion for which the Fast Marching Surface Tomography (FMST) code developed by N. Rawlinson at the Australian National University was utilized. This software package is based on the multistage fast marching method by Rawlinson and Sambridge (2004a, 2004b). The
Atashi, H; Zamiri, M J; Dadpasand, M
2013-06-01
In this study, 65,971 lactations on 41,842 cows in 64 herds were used to determine the association between dry period length (DPL) and lactation performance, lactation curve, calf birth weight, and the incidence of calving difficulty during the subsequent parity in Holstein dairy cows in Iran. The length of the dry period was classified into 7 categories: 0 to 35d, 36 to 50d, 51 to 60d, 61 to 70d, 71 to 85d, 86 to 110d, and 111 to 160d. Cows with the standard DPL (51 to 60d) produced more 305-d milk, fat, and protein over the next lactation compared with those with shorter dry periods. Shorter dry periods (0 to 35d and 36 to 50d) were associated with lower initial milk yield, steeper inclining and declining slopes of the lactation curve, and higher milk persistency compared with dry period length of 51 to 60d. Peak lactation was achieved later in cows with 0- to 35-d and 36- to 50-d dry period length than in those with dry period length of 51 to 60d. We also observed a relationship between DPL and calf birth weight: smaller calf birth weight was recorded with a dry period of 51 to 60d compared with longer dry periods. The incidence of calving difficulty did not differ in cows with 51- to 60-d dry period compared with cows with 0- to 35-d and 36- to 50-d dry periods. In conclusion, the results of this study did not support previous findings that suggested a shorter dry period could be beneficial to dairy production.
Comparison of lifetime-based methods for 2D phosphor thermometry in high-temperature environment
NASA Astrophysics Data System (ADS)
Peng, Di; Liu, Yingzheng; Zhao, Xiaofeng; Kim, Kyung Chun
2016-09-01
This paper discusses the currently available techniques for 2D phosphor thermometry, and compares the performance of two lifetime-based methods: high-speed imaging and the dual-gate. High-speed imaging resolves luminescent decay with a fast frame rate, and has become a popular method for phosphor thermometry in recent years. But it has disadvantages such as high equipment cost and long data processing time, and it would fail at sufficiently high temperature due to a low signal-to-noise ratio and short lifetime. The dual-gate method only requires two images on the decay curve and therefore greatly reduces cost in hardware and processing time. A dual-gate method for phosphor thermometry has been developed and compared with the high-speed imaging method through both calibration and a jet impingement experiment. Measurement uncertainty has been evaluated for a temperature range of 473–833 K. The effects of several key factors on uncertainty have been discussed, including the luminescent signal level, the decay lifetime and temperature sensitivity. The results show that both methods are valid for 2D temperature sensing within the given range. The high-speed imaging method shows less uncertainty at low temperatures where the signal level and the lifetime are both sufficient, but its performance is degraded at higher temperatures due to a rapidly reduced signal and lifetime. For T > 750 K, the dual-gate method outperforms the high-speed imaging method thanks to its superiority in signal-to-noise ratio and temperature sensitivity. The dual-gate method has great potential for applications in high-temperature environments where the high-speed imaging method is not applicable.
Comparison of lifetime-based methods for 2D phosphor thermometry in high-temperature environment
NASA Astrophysics Data System (ADS)
Peng, Di; Liu, Yingzheng; Zhao, Xiaofeng; Kim, Kyung Chun
2016-09-01
This paper discusses the currently available techniques for 2D phosphor thermometry, and compares the performance of two lifetime-based methods: high-speed imaging and the dual-gate. High-speed imaging resolves luminescent decay with a fast frame rate, and has become a popular method for phosphor thermometry in recent years. But it has disadvantages such as high equipment cost and long data processing time, and it would fail at sufficiently high temperature due to a low signal-to-noise ratio and short lifetime. The dual-gate method only requires two images on the decay curve and therefore greatly reduces cost in hardware and processing time. A dual-gate method for phosphor thermometry has been developed and compared with the high-speed imaging method through both calibration and a jet impingement experiment. Measurement uncertainty has been evaluated for a temperature range of 473-833 K. The effects of several key factors on uncertainty have been discussed, including the luminescent signal level, the decay lifetime and temperature sensitivity. The results show that both methods are valid for 2D temperature sensing within the given range. The high-speed imaging method shows less uncertainty at low temperatures where the signal level and the lifetime are both sufficient, but its performance is degraded at higher temperatures due to a rapidly reduced signal and lifetime. For T > 750 K, the dual-gate method outperforms the high-speed imaging method thanks to its superiority in signal-to-noise ratio and temperature sensitivity. The dual-gate method has great potential for applications in high-temperature environments where the high-speed imaging method is not applicable.
The strength of heterogeneous volcanic rocks: A 2D approximation
NASA Astrophysics Data System (ADS)
Heap, Michael J.; Wadsworth, Fabian B.; Xu, Tao; Chen, Chong-feng; Tang, Chun'an
2016-06-01
Volcanic rocks typically contain heterogeneities in the form of crystals and pores. We investigate here the influence of such heterogeneity on the strength of volcanic rocks using an elastic damage mechanics model in which we numerically deform two-dimensional samples comprising low-strength elements representing crystals and zero-strength elements representing pores. These circular elements are stochastically generated so that there is no overlap in a medium representing the groundmass. Our modelling indicates that increasing the fraction of pores and/or crystals reduces the strength of volcanic rocks, and that increasing the pore fraction results in larger strength reductions than increasing the crystal fraction. The model also highlights an important weakening role for pore diameter, but finds that crystal diameter has a less significant influence for strength. To account for heterogeneity (pores and crystals), we propose an effective medium approach where we define an effective pore fraction ϕp‧ = Vp/(Vp + Vg) where Vp and Vg are the pore and groundmass fractions, respectively. Highly heterogeneous samples (containing high pore and/or crystal fractions) will therefore have high values of ϕp‧, and vice-versa. When we express our numerical samples (more than 200 simulations spanning a wide range of crystal and pore fractions) in terms of ϕp‧, we find that their strengths can be described by a single curve for a given pore diameter. To provide a predictive tool for the strength of heterogeneous volcanic rocks, we propose a modified version of 2D solution for the Sammis and Ashby (1986) pore-emanating crack model, a micromechanical model designed to estimate strength using microstructural attributes such as porosity, pore radius, and fracture toughness. The model, reformulated to include ϕp‧ (and therefore crystal fraction), captures the strength curves for our numerical simulations over a sample heterogeneity range relevant to volcanic systems. We find
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.
Yamaçake, Kleiton Gabriel Ribeiro; Nakano, Elcio Tadashi; Soares, Iva Barbosa; Cordeiro, Paulo; Srougi, Miguel; Antunes, Alberto Azoubel
2015-01-01
Objective To evaluate the learning curve for transurethral resection of the prostate (TURP) among urology residents and study the impact of video game and musical instrument playing abilities on its performance. Material and methods A prospective study was performed from July 2009 to January 2013 with patients submitted to TURP for benign prostatic hyperplasia. Fourteen residents operated on 324 patients. The following parameters were analyzed: age, prostate-specific antigen levels, prostate weight on ultrasound, pre- and postoperative serum sodium and hemoglobin levels, weight of resected tissue, operation time, speed of resection, and incidence of capsular lesions. Gender, handedness, and prior musical instrument and video game playing experience were recorded using survey responses. Results The mean resection speed in the first 10 procedures was 0.36 g/min and reached a mean of 0.51 g/min after the 20th procedure. The incidence of capsular lesions decreased progressively. The operation time decreased progressively for each subgroup regardless of the difference in the weight of tissue resected. Those experienced in playing video games presented superior resection speed (0.45 g/min) when compared with the novice (0.35 g/min) and intermediate (0.38 g/min) groups (p=0.112). Musical instrument playing abilities did not affect the surgical performance. Conclusion Speed of resection, weight of resected tissue, and percentage of resected tissue improve significantly and the incidence of capsular lesions reduces after the performance of 10 TURP procedures. Experience in playing video games or musical instruments does not have a significant effect on outcomes. PMID:26516596
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.
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
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
Report of the 1988 2-D Intercomparison Workshop, chapter 3
NASA Technical Reports Server (NTRS)
Jackman, Charles H.; Brasseur, Guy; Soloman, Susan; Guthrie, Paul D.; Garcia, Rolando; Yung, Yuk L.; Gray, Lesley J.; Tung, K. K.; Ko, Malcolm K. W.; Isaken, Ivar
1989-01-01
Several factors contribute to the errors encountered. With the exception of the line-by-line model, all of the models employ simplifying assumptions that place fundamental limits on their accuracy and range of validity. For example, all 2-D modeling groups use the diffusivity factor approximation. This approximation produces little error in tropospheric H2O and CO2 cooling rates, but can produce significant errors in CO2 and O3 cooling rates at the stratopause. All models suffer from fundamental uncertainties in shapes and strengths of spectral lines. Thermal flux algorithms being used in 2-D tracer tranport models produce cooling rates that differ by as much as 40 percent for the same input model atmosphere. Disagreements of this magnitude are important since the thermal cooling rates must be subtracted from the almost-equal solar heating rates to derive the net radiative heating rates and the 2-D model diabatic circulation. For much of the annual cycle, the net radiative heating rates are comparable in magnitude to the cooling rate differences described. Many of the models underestimate the cooling rates in the middle and lower stratosphere. The consequences of these errors for the net heating rates and the diabatic circulation will depend on their meridional structure, which was not tested here. Other models underestimate the cooling near 1 mbar. Suchs errors pose potential problems for future interactive ozone assessment studies, since they could produce artificially-high temperatures and increased O3 destruction at these levels. These concerns suggest that a great deal of work is needed to improve the performance of thermal cooling rate algorithms used in the 2-D tracer transport models.
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
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.
2D and 3D ordered arrays of Co magnetic nanowires
NASA Astrophysics Data System (ADS)
Garcia, J.; Prida, V. M.; Vega, V.; Rosa, W. O.; Caballero-Flores, R.; Iglesias, L.; Hernando, B.
2015-06-01
Cobalt nanowire arrays spatially distributed in 2D and 3D arrangements have been performed by pulsed electrodeposition into the pores of planar and cylindrical nanoporous anodic alumina membranes, respectively. Morphological characterization points out the good filling factor reached by electroplated Co nanowires in both kinds of alumina membranes exhibiting hexagonally self-ordered porous structures. Co nanowires grown in both kinds of alumina templates exhibit the same crystalline phases. DC magnetometry and First Order Reversal Curve (FORC) analysis were carried out in order to determine the overall magnetic behavior for both nanowire array geometries. It is found that when the Co nanowires of two kinds of arrays are perpendicularly magnetized, both hysteresis loops are identical, suggesting that neither the intrinsic magnetic behavior of the nanowires nor the collective one depend on the arrays geometry. FORC analysis performed along the radial direction of the Co nanowire arrays embedded in the cylindrical alumina template reveals that the contribution of each nanowire to the magnetization reversal process involves its specific orientation with respect to the applied field direction. Furthermore, the comparison between the magnetic properties for both kinds of Co nanowire arrays allows discussing about the effect of the cylindrical geometry of the template on the magnetostatic interaction among nanowires.
Verification measurements of an eMC algorithm using a 2D ion chamber array.
Wanklyn, Mark D; Kidane, Ghirmay; Crees, Liz
2016-01-01
The aim of this study was to assess the suitability of the Im'RT MatriXX 2D ion chamber array for performing verification measurements on the Varian Eclipse electron Monte Carlo (eMC) algorithm for a range of clinical energies (6, 12, and 20 MeV) on a Varian 2100iX linear accelerator. Firstly, the suitability of the MatriXX for measuring percentage depth doses (PDD) in water was assessed, including characterization of the inherent buildup found in the MatriXX. Secondly the suitability of the MatriXX for measuring dose distributions in homogeneous and heterogeneous phantoms was assessed using gamma analysis at 3%/3 mm. It was found that after adjusting the PDD curves for the inherent buildup, that the position of R50,D measured using the MatriXX agreed to within 1 mm to the PDDs generated using the eMC algorithm for all energies used in this study. Gamma analysis at 3%/3mm showed very good agreement (> 95%) for all cases in both homogeneous and heterogeneous phantoms. It was concluded that the Im'RT MatriXX is a suitable device for performing eMC verification and could potentially be used for routine energy checks of electron beams. PMID:27685111
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.
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).
The general efficiency curve for air propellers
NASA Technical Reports Server (NTRS)
Diehl, Walter S
1924-01-01
This report presents a formula which may be used to obtain a "general efficiency curve" in addition to the well-known maximum efficiency curve. These two curves, when modified somewhat by experimental data, enable performance calculations to be made without detailed knowledge of the propeller. The curves may also be used to estimate the improvement in efficiency due to reduction gearing, or to judge the performance of a new propeller design.
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
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.
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.
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.
Hakimzadeh, Neda; Parastar, Hadi; Fattahi, Mohammad
2014-01-24
In this study, multivariate curve resolution (MCR) and multivariate classification methods are proposed to develop a new chemometric strategy for comprehensive analysis of high-performance liquid chromatography-diode array absorbance detection (HPLC-DAD) fingerprints of sixty Salvia reuterana samples from five different geographical regions. Different chromatographic problems occurred during HPLC-DAD analysis of S. reuterana samples, such as baseline/background contribution and noise, low signal-to-noise ratio (S/N), asymmetric peaks, elution time shifts, and peak overlap are handled using the proposed strategy. In this way, chromatographic fingerprints of sixty samples are properly segmented to ten common chromatographic regions using local rank analysis and then, the corresponding segments are column-wise augmented for subsequent MCR analysis. Extended multivariate curve resolution-alternating least squares (MCR-ALS) is used to obtain pure component profiles in each segment. In general, thirty-one chemical components were resolved using MCR-ALS in sixty S. reuterana samples and the lack of fit (LOF) values of MCR-ALS models were below 10.0% in all cases. Pure spectral profiles are considered for identification of chemical components by comparing their resolved spectra with the standard ones and twenty-four components out of thirty-one components were identified. Additionally, pure elution profiles are used to obtain relative concentrations of chemical components in different samples for multivariate classification analysis by principal component analysis (PCA) and k-nearest neighbors (kNN). Inspection of the PCA score plot (explaining 76.1% of variance accounted for three PCs) showed that S. reuterana samples belong to four clusters. The degree of class separation (DCS) which quantifies the distance separating clusters in relation to the scatter within each cluster is calculated for four clusters and it was in the range of 1.6-5.8. These results are then
Detecting curves with unknown endpoints and arbitrary topology using minimal paths.
Kaul, Vivek; Yezzi, Anthony; Tsai, Yichang James
2012-10-01
Existing state-of-the-art minimal path techniques work well to extract simple open curves in images when both endpoints of the curve are given as user input or when one input is given and the total length of the curve is known in advance. Curves which branch require even further prior input from the user, namely, each branch endpoint. In this work, we present a novel minimal path-based algorithm which works on much more general curve topologies with far fewer demands on the user for initial input compared to prior minimal path-based algorithms. The two key novelties and benefits of this new approach are that 1) it may be used to detect both open and closed curves, including more complex topologies containing both multiple branch points and multiple closed cycles without requiring a priori knowledge about which of these types is to be extracted, and 2) it requires only a single input point which, in contrast to existing methods, is no longer constrained to be an endpoint of the desired curve but may in fact be ANY point along the desired curve (even an internal point). We perform quantitative evaluation of the algorithm on 48 images (44 pavement crack images, 1 catheter tube image, and 3 retinal images) against human supplied ground truth. The results demonstrate that the algorithm is indeed able to extract curve-like objects accurately from images with far less prior knowledge and less user interaction compared to existing state-of-the-art minimal path-based image processing algorithms. In the future, the algorithm can be applied to other 2D curve-like objects and it can be extended to detect 3D curves.
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.
Cho, Sunggoo
2016-09-01
Conics and Cartesian ovals are extremely important curves in various fields of science. In addition, aspheric curves based on conics are useful in optical design. Superconic curves, recently suggested by Greynolds, are extensions of both conics and Cartesian ovals and have been applied to optical design. However, they are not extensions of aspheric curves based on conics. In this work, we investigate another type of superconic curves. These superconic curves are extensions of not only conics and Cartesian ovals but also aspheric curves based on conics. Moreover, these are represented in explicit form, while Greynolds's superconic curves are in implicit form. PMID:27607506
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.
Synthesize function for describing distorted 2-D magnetotelluric responses caused by topography
NASA Astrophysics Data System (ADS)
Promdee, Ninrat; Sarakorn, Weerachai
2016-04-01
In this research, the distortions of 2-D magnetotelluric responses caused by topographies are described by an appropriated synthesize functions. The damping wave equations and the considered topographic curves are used as the kernel of selected synthesize functions. The parameters of those functions are estimated by using the randomized neighborhood search method. The validity of functions is tested on half-space and COMMEMI2D-1 models with cosinusoidal, Gaussian and logistic topographic curves. The obtained results indicate that distorted apparent resistivity are well described by the selected synthesize functions with an acceptable root mean square errors. The obtained values of parameters are varied on both periods of EM wave and height of topographies.
2D-Cosy NMR Spectroscopy as a Quantitative Tool in Biological Matrix: Application to Cyclodextrins.
Dufour, Gilles; Evrard, Brigitte; de Tullio, Pascal
2015-11-01
Classical analytical quantifications in biological matrices require time-consuming sample pre-treatments and extractions. Nuclear magnetic resonance (NMR) analysis does not require heavy sample treatments or extractions which therefore increases its accuracy in quantification. In this study, even if quantitative (q)NMR could not be applied to 2D spectra, we demonstrated that cross-correlations and diagonal peak intensities have a linear relationship with the analyzed pharmaceutical compound concentration. This work presents the validation process of a 2D-correlation spectroscopy (COSY) NMR quantification of 2-hydroxypropyl-β-cyclodextrin in plasma. Specificity, linearity, precision (repeatability and intermediate precision), trueness, limits of quantification (LOQs), and accuracy were used as validation criteria. 2D-NMR could therefore be used as a valuable and accurate analytical technique for the quantification of pharmaceutical compounds, including hardly detectable compounds such as cyclodextrins or poloxamers, in complex biological matrices based on a calibration curve approach.
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.
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.
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..
Suspended 2-D photonic crystal aluminum nitride membrane reflector.
Ho, Chong Pei; Pitchappa, Prakash; Soon, Bo Woon; Lee, Chengkuo
2015-04-20
We experimentally demonstrated a free-standing two-dimensional (2-D) photonic crystal (PhC) aluminum nitride (AlN) membrane to function as a free space (or out-of-plane) reflector working in the mid infrared region. By etching circular holes of radius 620nm in a 330nm thick AlN slab, greater than 90% reflection was measured from 3.08μm to 3.78μm, with the peak reflection of 96% at 3.16μm. Due to the relatively low refractive index of AlN, we also investigated the importance of employing methods such as sacrificial layer release to enhance the performance of the PhC. In addition, characterization of the AlN based PhC was also done up to 450°C to examine the impact of thermo-optic effect on the performance. Despite the high temperature operation, the redshift in the peak reflection wavelengths of the device was estimated to be only 14.1nm. This equates to a relatively low thermo-optic coefficient 2.22 × 10(-5) K(-1) for AlN. Such insensitivity to thermo-optic effect makes AlN based 2-D PhC a promising technology to be used as photonic components for high temperature applications such as Fabry-Perot interferometer used for gas sensing in down-hole oil drilling and ruggedized electronics. PMID:25969099
Suspended 2-D photonic crystal aluminum nitride membrane reflector.
Ho, Chong Pei; Pitchappa, Prakash; Soon, Bo Woon; Lee, Chengkuo
2015-04-20
We experimentally demonstrated a free-standing two-dimensional (2-D) photonic crystal (PhC) aluminum nitride (AlN) membrane to function as a free space (or out-of-plane) reflector working in the mid infrared region. By etching circular holes of radius 620nm in a 330nm thick AlN slab, greater than 90% reflection was measured from 3.08μm to 3.78μm, with the peak reflection of 96% at 3.16μm. Due to the relatively low refractive index of AlN, we also investigated the importance of employing methods such as sacrificial layer release to enhance the performance of the PhC. In addition, characterization of the AlN based PhC was also done up to 450°C to examine the impact of thermo-optic effect on the performance. Despite the high temperature operation, the redshift in the peak reflection wavelengths of the device was estimated to be only 14.1nm. This equates to a relatively low thermo-optic coefficient 2.22 × 10(-5) K(-1) for AlN. Such insensitivity to thermo-optic effect makes AlN based 2-D PhC a promising technology to be used as photonic components for high temperature applications such as Fabry-Perot interferometer used for gas sensing in down-hole oil drilling and ruggedized electronics.
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)
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.
TOPAZ2D validation status report, August 1990
Davis, B.
1990-08-01
Analytic solutions to two heat transfer problems were used to partially evaluate the performance TOPAZ, and LLNL finite element heat transfer code. The two benchmark analytic solutions were for: 2D steady state slab, with constant properties, constant uniform temperature boundary conditions on three sides, and constant temperature distribution according to a sine function on the fourth side; 1D transient non-linear, with temperature dependent conductivity and specific heat (varying such that the thermal diffusivity remained constant), constant heat flux on the front face and adiabatic conditions on the other face. The TOPAZ solution converged to the analytic solution in both the transient and the steady state problem. Consistent mass matrix type of analysis yielded best performance for the transient problem, in the late-time response; but notable unnatural anomalies were observed in the early-time temperature response at nodal locations near the front face. 5 refs., 22 figs.
'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
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
Lack of association between schizophrenia and the CYP2D6 gene polymorphisms
Pirmohamed, M.; Wild, M.J.; Kitteringham, N.R.
1996-04-09
Approximately 5-10% of the Caucasian population lack the P450 isoform, CYP2D6. This polymorphism may be of importance in determining individual susceptibility to Parkinson`s disease. In this journal, Daniels et al. recently reported a negative association between the CYP2D6 gene locus and schizophrenia, a disease characterized by dopamine overactivity. It is important to exclude such an association because CYP2D6 is expressed in the brain and it is involved in dopamine catabolism. Between 1992 and 1993, we also performed a study similar to that, and reached the same conclusion. 7 refs., 1 tab.
Outcoupling efficiency of OLEDs with 2D periodical corrugation at the cathode
NASA Astrophysics Data System (ADS)
Belousov, Sergei; Bogdanova, Maria; Teslyuk, Anton
2016-03-01
We study theoretically the optical performance of organic light-emitting diodes (OLEDs) with 2D periodical corrugation at the cathode. We show how emergence of radiative surface plasmon resonances at the 2D corrugated cathode leads to the enhancement of the outcoupling efficiency of the OLED, which is primarily due to the outcoupling of emission generated by vertically oriented emitting excitons in the emission layer. We analyze the outcoupling efficiency of the OLED as a function of geometrical parameters of the corrugation and establish design rules for optimal outcoupling enhancement with the 2D corrugation at the cathode.
NASA Astrophysics Data System (ADS)
Ambrico, Paolo F.; Ambrico, Marianna; Schiavulli, Luigi; De Benedictis, Santolo
2014-07-01
The charge trapping effect due to the exposure of alumina surfaces to plasma has been studied in a volume dielectric barrier discharge (DBD) in Ar and He noble gases. The long lasting charge trapping of alumina dielectric plates, used as barriers in DBDs, is evidenced by an ex situ thermoluminescence (TL) experiment performed with a standard and a custom two-dimensional (2D)-TL apparatus. The spatial density of trapped surface charges is found to be strongly correlated to the plasma morphology, and the surface spatial memory lasted for several minutes to hours after plasma exposure. In the case of Ar, the plasma channel impact signature on the surface shows a higher equivalent radiation dose with respect to the surface plasma wave and the post-discharge species signature. As a consequence, for the development of discharges, inside the dielectric surface the availability of lower energy trapped electrons is larger in the first region of plasma impact. The reported spatial memory increases the likelihood of the occurrence of plasma filaments in the same position in different runs. In He plasmas, the dielectric barrier shows an almost uniform distribution of trapped charges, meaning that there is no preferred region for the development of the discharge. In all cases a slight asymmetry was shown in the direction of the gas flow. This can be interpreted as being due to the long-living species moving in the direction of the gas flow, corresponding with the TL side experiment on the sample exposed to the plasma afterglow. The maximum values and the integral of the 2D-TL images showed a linear relation with the total charge per ac cycle, corresponding with findings for the TL glow curve. In conclusion, 2D-TL images allow the retrieval of information regarding the plasma surface interaction such as the plasma morphology, trap sites and their activation temperature.
SAR imaging via modern 2-D spectral estimation methods.
DeGraaf, S R
1998-01-01
This paper discusses the use of modern 2D spectral estimation algorithms for synthetic aperture radar (SAR) imaging. The motivation for applying power spectrum estimation methods to SAR imaging is to improve resolution, remove sidelobe artifacts, and reduce speckle compared to what is possible with conventional Fourier transform SAR imaging techniques. This paper makes two principal contributions to the field of adaptive SAR imaging. First, it is a comprehensive comparison of 2D spectral estimation methods for SAR imaging. It provides a synopsis of the algorithms available, discusses their relative merits for SAR imaging, and illustrates their performance on simulated and collected SAR imagery. Some of the algorithms presented or their derivations are new, as are some of the insights into or analyses of the algorithms. Second, this work develops multichannel variants of four related algorithms, minimum variance method (MVM), reduced-rank MVM (RRMVM), adaptive sidelobe reduction (ASR) and space variant apodization (SVA) to estimate both reflectivity intensity and interferometric height from polarimetric displaced-aperture interferometric data. All of these interferometric variants are new. In the interferometric contest, adaptive spectral estimation can improve the height estimates through a combination of adaptive nulling and averaging. Examples illustrate that MVM, ASR, and SVA offer significant advantages over Fourier methods for estimating both scattering intensity and interferometric height, and allow empirical comparison of the accuracies of Fourier, MVM, ASR, and SVA interferometric height estimates.
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
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.
Flatbands in 2D boroxine-linked covalent organic frameworks.
Wang, Rui-Ning; Zhang, Xin-Ran; Wang, Shu-Fang; Fu, Guang-Sheng; Wang, Jiang-Long
2016-01-14
Density functional calculations have been performed to analyze the electronic and mechanical properties of a number of 2D boroxine-linked covalent organic frameworks (COFs), which are experimentally fabricated from di-borate aromatic molecules. Furthermore, the band structures are surprising and show flat-band characteristics which are mainly attributed to the delocalized π-conjugated electrons around the phenyl rings and can be better understood within aromaticity theories. Next, the effects of branch sizes and hydrostatic strains on their band structures are systematically considered within generalized gradient approximations. It is found that their band gaps will start to saturate when the branch size reaches 9. For boroxine-linked COFs with only one benzene ring in the branch, the band gap is robust under compressive strain while it decreases with the tensile strain increasing. When the branch size is equal or greater than 2, their band gaps will monotonously increase with the strain increasing in the range of [-1.0, 2.0] Å. All boroxine-linked COFs are semiconductors with controllable band gaps, depending on the branch length and the applied strain. In comparison with other 2D materials, such as graphene, hexagonal boron nitride, and even γ-graphyne, all boroxine-linked COFs are much softer and even more stable. That is, they can maintain the planar features under a larger compressive strain, which means that they are good candidates in flexible electronics. PMID:26662215
Peak width issues with generalised 2D correlation NMR spectroscopy
NASA Astrophysics Data System (ADS)
Kirwan, Gemma M.; Adams, Michael J.
2008-12-01
Two-dimensional spectral correlation analysis is shown to be sensitive to fluctuations in spectral peak width as a function of perturbation variable. This is particularly significant where peak width fluctuations are of similar order of magnitude as the peak width values themselves and where changes in peak width are not random but are, for example, proportional to intensity. In such cases these trends appear in the asynchronous matrix as false peaks that serve to interfere with interpretation of the data. Complex, narrow band spectra such as provided by 1H NMR spectroscopy are demonstrated to be prone to such interference. 2D correlation analysis was applied to a series of NMR spectra corresponding to a commercial wine fermentation, in which the samples collected over a period of several days exhibit dramatic changes in concentration of minor and major components. The interference due to changing peak width effects is eliminated by synthesizing the recorded spectra using a constant peak width value prior to performing 2D correlation analysis.
Flatbands in 2D boroxine-linked covalent organic frameworks.
Wang, Rui-Ning; Zhang, Xin-Ran; Wang, Shu-Fang; Fu, Guang-Sheng; Wang, Jiang-Long
2016-01-14
Density functional calculations have been performed to analyze the electronic and mechanical properties of a number of 2D boroxine-linked covalent organic frameworks (COFs), which are experimentally fabricated from di-borate aromatic molecules. Furthermore, the band structures are surprising and show flat-band characteristics which are mainly attributed to the delocalized π-conjugated electrons around the phenyl rings and can be better understood within aromaticity theories. Next, the effects of branch sizes and hydrostatic strains on their band structures are systematically considered within generalized gradient approximations. It is found that their band gaps will start to saturate when the branch size reaches 9. For boroxine-linked COFs with only one benzene ring in the branch, the band gap is robust under compressive strain while it decreases with the tensile strain increasing. When the branch size is equal or greater than 2, their band gaps will monotonously increase with the strain increasing in the range of [-1.0, 2.0] Å. All boroxine-linked COFs are semiconductors with controllable band gaps, depending on the branch length and the applied strain. In comparison with other 2D materials, such as graphene, hexagonal boron nitride, and even γ-graphyne, all boroxine-linked COFs are much softer and even more stable. That is, they can maintain the planar features under a larger compressive strain, which means that they are good candidates in flexible electronics.
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
2D-MoO3 nanosheets for superior gas sensors.
Ji, Fangxu; Ren, Xianpei; Zheng, Xiaoyao; Liu, Yucheng; Pang, Liuqing; Jiang, Jiaxing; Liu, Shengzhong Frank
2016-04-28
By taking advantages of both grinding and sonication, an effective exfoliation process is developed to prepare two-dimensional (2D) molybdenum oxide (MoO3) nanosheets. The approach avoids high-boiling-point solvents that would leave a residue and cause aggregation. Gas sensors fabricated using the 2D-MoO3 nanosheets provide a significantly enhanced chemical sensor performance. Compared with the sensors using bulk MoO3, the response of the 2D-MoO3 sensor increases from 7 to 33; the sensor response time is reduced from 27 to 21 seconds, and the recovery time is shortened from 26 to 10 seconds. We attribute the superior performance to the 2D-structure with a much increased surface area and reactive sites. PMID:27053379
Givehchi, Alireza; Bender, Andreas; Glen, Robert C
2006-01-01
The effect of multitarget dependent descriptor transformation on classification performance is explored in this work. To this end decision trees as well as neural net QSAR in combination with PLS were applied to predict the activity class of 5HT3 ligands, angiotensin converting enzyme inhibitors, 3-hydroxyl-3-methyl glutaryl coenzyme A reductase inhibitors, platelet activating factor antagonists, and thromboxane A2 antagonists. Physicochemical descriptors calculated by MOE and fragment-based descriptors (MOLPRINT 2D) were employed to generate descriptor vectors. In a subsequent step the physicochemical descriptor vectors were transformed to a lower dimensional space using multitarget dependent descriptor transformation. Cross-validation of the original physicochemical descriptors in combination with decision trees and neural net QSAR as well as cross-validation of PLS multitarget transformed descriptors with neural net QSAR were performed. For comparison this was repeated using fragment-based descriptors in combination with decision trees.
2D-MoO3 nanosheets for superior gas sensors
NASA Astrophysics Data System (ADS)
Ji, Fangxu; Ren, Xianpei; Zheng, Xiaoyao; Liu, Yucheng; Pang, Liuqing; Jiang, Jiaxing; Liu, Shengzhong (Frank)
2016-04-01
By taking advantages of both grinding and sonication, an effective exfoliation process is developed to prepare two-dimensional (2D) molybdenum oxide (MoO3) nanosheets. The approach avoids high-boiling-point solvents that would leave a residue and cause aggregation. Gas sensors fabricated using the 2D-MoO3 nanosheets provide a significantly enhanced chemical sensor performance. Compared with the sensors using bulk MoO3, the response of the 2D-MoO3 sensor increases from 7 to 33; the sensor response time is reduced from 27 to 21 seconds, and the recovery time is shortened from 26 to 10 seconds. We attribute the superior performance to the 2D-structure with a much increased surface area and reactive sites.By taking advantages of both grinding and sonication, an effective exfoliation process is developed to prepare two-dimensional (2D) molybdenum oxide (MoO3) nanosheets. The approach avoids high-boiling-point solvents that would leave a residue and cause aggregation. Gas sensors fabricated using the 2D-MoO3 nanosheets provide a significantly enhanced chemical sensor performance. Compared with the sensors using bulk MoO3, the response of the 2D-MoO3 sensor increases from 7 to 33; the sensor response time is reduced from 27 to 21 seconds, and the recovery time is shortened from 26 to 10 seconds. We attribute the superior performance to the 2D-structure with a much increased surface area and reactive sites. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00880a
Interfacing graphene and related 2D materials with the 3D world.
Tománek, David
2015-04-10
An important prerequisite to translating the exceptional intrinsic performance of 2D materials such as graphene and transition metal dichalcogenides into useful devices precludes their successful integration within the current 3D technology. This review provides theoretical insight into nontrivial issues arising from interfacing 2D materials with 3D systems including epitaxy and ways to accommodate lattice mismatch, the key role of contact resistance and the effect of defects in electrical and thermal transport.
Wei, Jun; Chan, Heang-Ping; Hadjiiski, Lubomir M.; Helvie, Mark A.; Lu, Yao; Zhou, Chuan; Samala, Ravi
2014-01-01
Purpose: To investigate the feasibility of a new two-dimensional (2D) multichannel response (MCR) analysis approach for the detection of clustered microcalcifications (MCs) in digital breast tomosynthesis (DBT). Methods: With IRB approval and informed consent, a data set of two-view DBTs from 42 breasts containing biopsy-proven MC clusters was collected in this study. The authors developed a 2D approach for MC detection using projection view (PV) images rather than the reconstructed three-dimensional (3D) DBT volume. Signal-to-noise ratio (SNR) enhancement processing was first applied to each PV to enhance the potential MCs. The locations of MC candidates were then identified with iterative thresholding. The individual MCs were decomposed with Hermite–Gaussian (HG) and Laguerre–Gaussian (LG) basis functions and the channelized Hotelling model was trained to produce the MCRs for each MC on the 2D images. The MCRs from the PVs were fused in 3D by a coincidence counting method that backprojects the MC candidates on the PVs and traces the coincidence of their ray paths in 3D. The 3D MCR was used to differentiate the true MCs from false positives (FPs). Finally a dynamic clustering method was used to identify the potential MC clusters in the DBT volume based on the fact that true MCs of clinical significance appear in clusters. Using two-fold cross validation, the performance of the 3D MCR for classification of true and false MCs was estimated by the area under the receiver operating characteristic (ROC) curve and the overall performance of the MCR approach for detection of clustered MCs was assessed by free response receiver operating characteristic (FROC) analysis. Results: When the HG basis function was used for MCR analysis, the detection of MC cluster achieved case-based test sensitivities of 80% and 90% at the average FP rates of 0.65 and 1.55 FPs per DBT volume, respectively. With LG basis function, the average FP rates were 0.62 and 1.57 per DBT volume at
Wei, Jun Chan, Heang-Ping; Hadjiiski, Lubomir M.; Helvie, Mark A.; Lu, Yao; Zhou, Chuan; Samala, Ravi
2014-04-15
Purpose: To investigate the feasibility of a new two-dimensional (2D) multichannel response (MCR) analysis approach for the detection of clustered microcalcifications (MCs) in digital breast tomosynthesis (DBT). Methods: With IRB approval and informed consent, a data set of two-view DBTs from 42 breasts containing biopsy-proven MC clusters was collected in this study. The authors developed a 2D approach for MC detection using projection view (PV) images rather than the reconstructed three-dimensional (3D) DBT volume. Signal-to-noise ratio (SNR) enhancement processing was first applied to each PV to enhance the potential MCs. The locations of MC candidates were then identified with iterative thresholding. The individual MCs were decomposed with Hermite–Gaussian (HG) and Laguerre–Gaussian (LG) basis functions and the channelized Hotelling model was trained to produce the MCRs for each MC on the 2D images. The MCRs from the PVs were fused in 3D by a coincidence counting method that backprojects the MC candidates on the PVs and traces the coincidence of their ray paths in 3D. The 3D MCR was used to differentiate the true MCs from false positives (FPs). Finally a dynamic clustering method was used to identify the potential MC clusters in the DBT volume based on the fact that true MCs of clinical significance appear in clusters. Using two-fold cross validation, the performance of the 3D MCR for classification of true and false MCs was estimated by the area under the receiver operating characteristic (ROC) curve and the overall performance of the MCR approach for detection of clustered MCs was assessed by free response receiver operating characteristic (FROC) analysis. Results: When the HG basis function was used for MCR analysis, the detection of MC cluster achieved case-based test sensitivities of 80% and 90% at the average FP rates of 0.65 and 1.55 FPs per DBT volume, respectively. With LG basis function, the average FP rates were 0.62 and 1.57 per DBT volume at
areaDetector: Software for 2-D Detectors in EPICS
Rivers, M.
2011-09-23
areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.
A full 2D IDCT with extreme low complexity
NASA Astrophysics Data System (ADS)
Navarro, Antonio; Silva, Antonio; Reznik, Yuriy
2007-09-01
In the context of a Call for Proposal for integer IDCTs issued by MPEG in July 2005, a full 2D integer IDCT based on a previous Feig and Winograd's work has been proposed. It achieves a high precision by meeting all IEEE1180 conditions and is suitable of implementation on hardware since it can be performed only with shifts and additions. Furthermore, it can be useful in high video resolution scenarios like in 720p/1080i/p due to its feedforward operation mode without any loop as usual in row-column implementations. The proposed transformation can be implemented without changing other functional blocks either at the encoder or at the decoder or alternatively as a scaled version incorporating the scaling factors into the dequantization stage. Our algorithm uses only 1328 operations for 8x8 blocks, including scaling factors.
areaDetector: Software for 2-D Detectors in EPICS
Rivers, Mark L.
2010-06-23
areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.
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.
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.
Wu, Zhi-Cheng; Xiao, Xuan; Chou, Kuo-Chen
2010-11-01
Introduction of graphic representation for biological sequences can provide intuitive overall pictures as well as useful insights for performing large-scale analysis. Here, a new two-dimensional graph, called "2D-MH", is proposed to represent protein sequences. It is formed by incorporating the information of the side-chain mass of each of the constituent amino acids and its hydrophobicity. The graphic curve thus generated is featured by (1) an one-to-one correspondence relation without circuit or degeneracy, (2) better reflecting the innate structure of the protein sequence, (3) clear visibility in displaying the similarity of protein sequences, (4) more sensitive for the mutation sites important for drug targeting, and (5) being able to be used as a metric for the "evolutionary distance" of a protein from one species to the other. It is anticipated that the presented graphic method may become a useful vehicle for large-scale analysis of the avalanche of protein sequences generated in the post-genomic age. As a web-server, 2D-MH is freely accessible at http://icpr.jci.jx.cn/bioinfo/pplot/2D-MH, by which one can easily generate the two-dimensional graphs for any number of protein sequences and compare the evolutionary distances between them.
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.
Fluctuating Pressure Data from 2-D Nozzle Cold Flow Tests (Dual Bell)
NASA Technical Reports Server (NTRS)
Nesman, Tomas E.
2001-01-01
Rocket engines nozzle performance changes as a vehicle climbs through the atmosphere. An altitude compensating nozzle, ACN, is intended to improve on a fixed geometry bell nozzle that performs at optimum at only one trajectory point. In addition to nozzle performance, nozzle transient loads are an important consideration. Any nozzle experiences large transient toads when shocks pass through the nozzle at start and shutdown. Additional transient toads will occur at transitional flow conditions. The objectives of cold flow nozzle testing at MSFC are CFD benchmark / calibration and Unsteady flow / sideloads. Initial testing performed with 2-D inserts to 14" transonic wind tunnel. Recent review of 2-D data in preparation for nozzle test facility 3-D testing. This presentation shows fluctuating pressure data and some observations from 2-D dual-bell nozzle cold flow tests.
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.
First measurements with the Munich 2D-ACAR spectrometer on Cr
NASA Astrophysics Data System (ADS)
Ceeh, Hubert; Weber, Josef; Hugenschmidt, Christoph; Leitner, Michael; Böni, Peter
2013-06-01
The Munich 2D-ACAR spectrometer at the Maier-Leibnitz accelerator laboratory in Garching has recently become operational. In the present implementation a 2D-ACAR spectrometer is set up, with a baseline of 16.5 m, a conventional 22Na positron source and two Anger-type gamma-cameras. The positrons are guided onto the sample by a magnetic field generated by a normal conducting electromagnet. The sample can be either cooled by a standard closed-cycle-cryostat to low temperatures or heated by a resistive filament to temperatures up to 500 K. We present the key features of this new 2D-ACAR spectrometer and, in addition, discuss first measurements on the pure metal system Cr. The 2D-ACAR measurements have been performed on Cr at different temperatures: at 5 K and at room temperature in the anti-ferromagnetic phase and at 318K slightly above the paramagnetic phase transition.
Few-layer III-VI and IV-VI 2D semiconductor transistors
NASA Astrophysics Data System (ADS)
Sucharitakul, Sukrit; Liu, Mei; Kumar, Rajesh; Sankar, Raman; Chou, Fang C.; Chen, Yit-Tsong; Gao, Xuan
Since the discovery of atomically thin graphene, a large variety of exfoliable 2D materials have been thoroughly explored for their exotic transport behavior and promises in technological breakthroughs. While most attention on 2D materials beyond graphene is focused on transition metal-dichalcogenides, relatively less attention is paid to layered III-VI and IV-VI semiconductors such as InSe, SnSe etc which bear stronger potential as 2D materials with high electron mobility or thermoelectric figure of merit. We will discuss our recent work on few-layer InSe 2D field effect transistors which exhibit carrier mobility approaching 1000 cm2/Vs and ON-OFF ratio exceeding 107 at room temperature. In addition, the fabrication and device performance of transistors made of mechanically exfoliated multilayer IV-VI semiconductor SnSe and SnSe2 will be discussed.
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.
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
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
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).
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.
Estimating 2-D vector velocities using multidimensional spectrum analysis.
Oddershede, Niels; Løvstakken, Lasse; Torp, Hans; Jensen, Jørgen Arendt
2008-08-01
Wilson (1991) presented an ultrasonic wideband estimator for axial blood flow velocity estimation through the use of the 2-D Fourier transform. It was shown how a single velocity component was concentrated along a line in the 2-D Fourier space, where the slope was given by the axial velocity. Later, it was shown that this approach could also be used for finding the lateral velocity component by also including a lateral sampling. A single velocity component would then be concentrated along a plane in the 3-D Fourier space, tilted according to the 2 velocity components. This paper presents 2 new velocity estimators for finding both the axial and lateral velocity components. The estimators essentially search for the plane in the 3- D Fourier space, where the integrated power spectrum is largest. The first uses the 3-D Fourier transform to find the power spectrum, while the second uses a minimum variance approach. Based on this plane, the axial and lateral velocity components are estimated. Several phantom measurements, for flow-to-depth angles of 60, 75, and 90 degrees, were performed. Multiple parallel lines were beamformed simultaneously, and 2 different receive apodization schemes were tried. The 2 estimators were then applied to the data. The axial velocity component was estimated with an average standard deviation below 2.8% of the peak velocity, while the average standard deviation of the lateral velocity estimates was between 2.0% and 16.4%. The 2 estimators were also tested on in vivo data from a transverse scan of the common carotid artery, showing the potential of the vector velocity estimation method under in vivo conditions. PMID:18986918
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.
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
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.
NASA Astrophysics Data System (ADS)
Mo, Yike; Greenhalgh, Stewart A.; Robertsson, Johan O. A.; Karaman, Hakki
2015-05-01
Lateral velocity variations and low velocity near-surface layers can produce strong scattered and guided waves which interfere with reflections and lead to severe imaging problems in seismic exploration. In order to investigate these specific problems by laboratory seismic modelling, a simple 2D ultrasonic model facility has been recently assembled within the Wave Propagation Lab at ETH Zurich. The simulated geological structures are constructed from 2 mm thick metal and plastic sheets, cut and bonded together. The experiments entail the use of a piezoelectric source driven by a pulse amplifier at ultrasonic frequencies to generate Lamb waves in the plate, which are detected by piezoelectric receivers and recorded digitally on a National Instruments recording system, under LabVIEW software control. The 2D models employed were constructed in-house in full recognition of the similitude relations. The first heterogeneous model features a flat uniform low velocity near-surface layer and deeper dipping and flat interfaces separating different materials. The second model is comparable but also incorporates two rectangular shaped inserts, one of low velocity, the other of high velocity. The third model is identical to the second other than it has an irregular low velocity surface layer of variable thickness. Reflection as well as transmission experiments (crosshole & vertical seismic profiling) were performed on each model. The two dominant Lamb waves recorded are the fundamental symmetric mode (non-dispersive) and the fundamental antisymmetric (flexural) dispersive mode, the latter normally being absent when the source transducer is located on a model edge but dominant when it is on the flat planar surface of the plate. Experimental group and phase velocity dispersion curves were determined and plotted for both modes in a uniform aluminium plate. For the reflection seismic data, various processing techniques were applied, as far as pre-stack Kirchhoff migration. The
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
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.
Progress in Complex 2D and 3D Cohesive Fracture Modelling Considering Random Heterogeneity
NASA Astrophysics Data System (ADS)
Yang, Zhenjun; Su, Xiangting; Chen, Jianfei; Liu, Guohua
2010-05-01
This paper summarises our recent efforts on finite element modelling of complex 2D and 3D fracture in quasi-brittle materials considering random heterogeneous fracture properties, using a simple yet effective method developed in associated with Abaqus. In this method, potential cracks are represented by pre-inserted cohesive elements with traction-separation softening constitutive laws modelled by spatially-varying Weibull random fields. Extensive Monte Carlo simulations of small-sized concrete specimens under uni-axial tension were carried out. It is found that the developed method is able to predict realistic 2D and 3D crack propagation processes and excellent load-displacement curves with little mesh-dependence. It provides a potentially powerful tool to assess reliability of existing structures against external loadings.
A New Curb Detection Method for Unmanned Ground Vehicles Using 2D Sequential Laser Data
Liu, Zhao; Wang, Jinling; Liu, Daxue
2013-01-01
Curb detection is an important research topic in environment perception, which is an essential part of unmanned ground vehicle (UGV) operations. In this paper, a new curb detection method using a 2D laser range finder in a semi-structured environment is presented. In the proposed method, firstly, a local Digital Elevation Map (DEM) is built using 2D sequential laser rangefinder data and vehicle state data in a dynamic environment and a probabilistic moving object deletion approach is proposed to cope with the effect of moving objects. Secondly, the curb candidate points are extracted based on the moving direction of the vehicle in the local DEM. Finally, the straight and curved curbs are detected by the Hough transform and the multi-model RANSAC algorithm, respectively. The proposed method can detect the curbs robustly in both static and typical dynamic environments. The proposed method has been verified in real vehicle experiments. PMID:23325170
A new curb detection method for unmanned ground vehicles using 2D sequential laser data.
Liu, Zhao; Wang, Jinling; Liu, Daxue
2013-01-01
Curb detection is an important research topic in environment perception, which is an essential part of unmanned ground vehicle (UGV) operations. In this paper, a new curb detection method using a 2D laser range finder in a semi-structured environment is presented. In the proposed method, firstly, a local Digital Elevation Map (DEM) is built using 2D sequential laser rangefinder data and vehicle state data in a dynamic environment and a probabilistic moving object deletion approach is proposed to cope with the effect of moving objects. Secondly, the curb candidate points are extracted based on the moving direction of the vehicle in the local DEM. Finally, the straight and curved curbs are detected by the Hough transform and the multi-model RANSAC algorithm, respectively. The proposed method can detect the curbs robustly in both static and typical dynamic environments. The proposed method has been verified in real vehicle experiments. PMID:23325170
The use of 2D and 3D information in a perceptual-cognitive judgement task.
Put, Koen; Wagemans, Johan; Spitz, Jochim; Gallardo, Manuel Armenteros; Williams, A Mark; Helsen, Werner F
2014-01-01
We examined whether the use of three-dimensional (3D) simulations in an off-field offside decision-making task is beneficial compared to the more widely available two-dimensional (2D) simulations. Thirty-three assistant referees, who were all involved in professional football, participated in the experiment. They assessed 40 offside situations in both 2D and 3D formats using a counterbalanced design. A distinction was made between offside situations near (i.e., 15 m) and far (i.e., 30 m) from the touchline. Subsequently, a frame recognition task was performed in which assistant referees were asked to indicate which of the five pictures represented the previous video scene. A higher response accuracy score was observed under 3D (80.0%) compared to 2D (75.0%) conditions, in particular for the situations near the touchline (3D: 81.8%; 2D: 72.7%). No differences were reported between 2D and 3D in the frame recognition task. Findings suggest that in highly dynamic and complex situations, the visual system can benefit from the availability of 3D information, especially for relatively fine, metric position judgements. In the memory task, in which a mental abstraction had to be made from a dynamic situation to a static snapshot, 3D stereo disparities do not add anything over and beyond 2D simulations. The specific task demands should be taken into account when considering the most appropriate format for testing and training. PMID:24857384
NASA Astrophysics Data System (ADS)
Jeromin, A.; Schaffarczyk, A. P.; Puczylowski, J.; Peinke, J.; Hölling, M.
2014-12-01
For the investigation of atmospheric turbulent flows on small scales a new anemometer was developed, the so-called 2d-Atmospheric Laser Cantilever Anemometer (2d-ALCA). It performs highly resolved measurements with a spatial resolution in millimeter range and temporal resolution in kHz range, thus detecting very small turbulent structures. The anemometer is a redesign of the successfully operating 2d-LCA for laboratory application. The new device was designed to withstand hostile operating environments (rain and saline, humid air). In February 2012, the 2d-ALCA was used for the first time in a test field. The device was mounted in about 53 m above ground level on a lattice tower near the German North Sea coast. Wind speed was measured by the 2d-ALCA at 10 kHz sampling rate and by cup anemometers at 1 Hz. The instantaneous wind speed ranged from 8 m/s to 19 m/s at an average turbulence level of about 7 %. Wind field characteristics were analyzed based on cup anemometer as well as 2d-ALCA. The combination of both devices allowed the study of atmospheric turbulence over several magnitudes in turbulent scales.
The use of 2D and 3D information in a perceptual-cognitive judgement task.
Put, Koen; Wagemans, Johan; Spitz, Jochim; Gallardo, Manuel Armenteros; Williams, A Mark; Helsen, Werner F
2014-01-01
We examined whether the use of three-dimensional (3D) simulations in an off-field offside decision-making task is beneficial compared to the more widely available two-dimensional (2D) simulations. Thirty-three assistant referees, who were all involved in professional football, participated in the experiment. They assessed 40 offside situations in both 2D and 3D formats using a counterbalanced design. A distinction was made between offside situations near (i.e., 15 m) and far (i.e., 30 m) from the touchline. Subsequently, a frame recognition task was performed in which assistant referees were asked to indicate which of the five pictures represented the previous video scene. A higher response accuracy score was observed under 3D (80.0%) compared to 2D (75.0%) conditions, in particular for the situations near the touchline (3D: 81.8%; 2D: 72.7%). No differences were reported between 2D and 3D in the frame recognition task. Findings suggest that in highly dynamic and complex situations, the visual system can benefit from the availability of 3D information, especially for relatively fine, metric position judgements. In the memory task, in which a mental abstraction had to be made from a dynamic situation to a static snapshot, 3D stereo disparities do not add anything over and beyond 2D simulations. The specific task demands should be taken into account when considering the most appropriate format for testing and training.
Effect of CYP2D6 genetic polymorphism on the metabolism of citalopram in vitro.
Hu, Xiao-Xia; Yuan, Ling-Jing; Fang, Ping; Mao, Yong-Hui; Zhan, Yun-Yun; Li, Xiang-Yu; Dai, Da-Peng; Cai, Jian-Ping; Hu, Guo-Xin
2016-04-01
Genetic polymorphisms of CYP2D6 significantly influence the efficacy and safety of some drugs, which might cause adverse effects and therapeutic failure. We aimed at investigating the role of CYP2D6 in the metabolism of citalopram and identifying the effect of 24 CYP2D6 allelic variants we found in Chinese Han population on the metabolism of citalopram in vitro. These CYP2D6 variants expressed by insect cells system were incubated with 10-1000 μM citalopram for 30 min at 37 °C and the reaction was terminated by cooling to -80 °C immediately. Citalopram and its metabolites were analyzed by high-performance liquid chromatography (HPLC). The intrinsic clearance (Vmax/Km) values of the variants toward citalopram metabolites were significantly altered, 38-129% for demethylcitalopram and 13-138% for citalopram N-oxide when compared with CYP2D6*1. Most of the tested rare alleles exhibited significantly decreased values due to increased Km and/or decreased Vmax values. We conclude that recombinant system could be used to investigate the enzymes involved in drug metabolism and these findings suggest that more attention should be paid to subjects carrying these CYP2D6 alleles when administering citalopram in the clinic. PMID:27016952
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
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
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.
Can exposure to prenatal sex hormones (2D:4D) predict cognitive reflection?
Bosch-Domènech, Antoni; Brañas-Garza, Pablo; Espín, Antonio M
2014-05-01
The Cognitive Reflection Test (CRT) is a test introduced by Frederick (2005). The task is designed to measure the tendency to override an intuitive response that is incorrect and to engage in further reflection that leads to the correct response. The consistent sex differences in CRT performance may suggest a role for prenatal sex hormones. A now widely studied putative marker for relative prenatal testosterone is the second-to-fourth digit ratio (2D:4D). This paper tests to what extent 2D:4D, as a proxy for the prenatal ratio of testosterone/estrogens, can predict CRT scores in a sample of 623 students. After controlling for sex, we observe that a lower 2D:4D (reflecting a relative higher exposure to testosterone) is significantly associated with a higher number of correct answers. The result holds for both hands' 2D:4Ds. In addition, the effect appears to be stronger for females than for males. We also control for patience and math proficiency, which are significantly related to performance in the CRT. But the effect of 2D:4D on performance in CRT is not reduced with these controls, implying that these variables are not mediating the relationship between digit ratio and CRT.
Boussuges, A; Carturan, D; Ambrosi, P; Habib, G; Sainty, J M; Luccioni, R
1998-01-01
The aim of this study was to determine the utility of pulsed Doppler and 2D echocardiography for the detection and the quantification of circulating bubbles after decompression. Twenty-three sport divers performed 60 SCUBA dives (mean 32 msw). An evaluation of circulating bubbles was performed using 2D images one hour after diving. Circulating bubbles were also detected with pulsed Doppler. The sample volume was placed in the outflow area of the right ventricle 1-2 cm below the pulmonary valve. 2D echocardiography showed circulating bubbles in right cavities of the heart in 32 cases. Short axis parasternal view and right cavities long axis view were the best incidences. Pulsed Doppler confirmed the results in these 32 cases and detected circulating bubbles in seven other cases. Isometric contraction of muscle limb must be performed to increase the sensitivity of detection. The count of the bubbles may be evaluated when using a combination of Spencer's and Powell's grading. We conclude that 2D echocardiography is less accurate than pulsed Doppler in the detection of circulating bubbles after decompression. Further studies are needed to compare pulsed Doppler guided by 2D echocardiography to continuous Doppler for the detection of circulating bubbles.
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.
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
Facial Sketch Synthesis Using 2D Direct Combined Model-Based Face-Specific Markov Network.
Tu, Ching-Ting; Chan, Yu-Hsien; Chen, Yi-Chung
2016-08-01
A facial sketch synthesis system is proposed, featuring a 2D direct combined model (2DDCM)-based face-specific Markov network. In contrast to the existing facial sketch synthesis systems, the proposed scheme aims to synthesize sketches, which reproduce the unique drawing style of a particular artist, where this drawing style is learned from a data set consisting of a large number of image/sketch pairwise training samples. The synthesis system comprises three modules, namely, a global module, a local module, and an enhancement module. The global module applies a 2DDCM approach to synthesize the global facial geometry and texture of the input image. The detailed texture is then added to the synthesized sketch in a local patch-based manner using a parametric 2DDCM model and a non-parametric Markov random field (MRF) network. Notably, the MRF approach gives the synthesized results an appearance more consistent with the drawing style of the training samples, while the 2DDCM approach enables the synthesis of outcomes with a more derivative style. As a result, the similarity between the synthesized sketches and the input images is greatly improved. Finally, a post-processing operation is performed to enhance the shadowed regions of the synthesized image by adding strong lines or curves to emphasize the lighting conditions. The experimental results confirm that the synthesized facial images are in good qualitative and quantitative agreement with the input images as well as the ground-truth sketches provided by the same artist. The representing power of the proposed framework is demonstrated by synthesizing facial sketches from input images with a wide variety of facial poses, lighting conditions, and races even when such images are not included in the training data set. Moreover, the practical applicability of the proposed framework is demonstrated by means of automatic facial recognition tests. PMID:27244737
Stringano, Elisabetta; Gea, An; Salminen, Juha-Pekka; Mueller-Harvey, Irene
2011-10-28
This study was undertaken to explore gel permeation chromatography (GPC) for estimating molecular weights of proanthocyanidin fractions isolated from sainfoin (Onobrychis viciifolia). The results were compared with data obtained by thiolytic degradation of the same fractions. Polystyrene, polyethylene glycol and polymethyl methacrylate standards were not suitable for estimating the molecular weights of underivatized proanthocyanidins. Therefore, a novel HPLC-GPC method was developed based on two serially connected PolarGel-L columns using DMF that contained 5% water, 1% acetic acid and 0.15 M LiBr at 0.7 ml/min and 50 °C. This yielded a single calibration curve for galloyl glucoses (trigalloyl glucose, pentagalloyl glucose), ellagitannins (pedunculagin, vescalagin, punicalagin, oenothein B, gemin A), proanthocyanidins (procyanidin B2, cinnamtannin B1), and several other polyphenols (catechin, epicatechin gallate, epicallocatechin gallate, amentoflavone). These GPC predicted molecular weights represented a considerable advance over previously reported HPLC-GPC methods for underivatized proanthocyanidins.
NASA Astrophysics Data System (ADS)
Kavčič, M.; Budnar, M.; Mühleisen, A.; Gasser, F.; Žitnik, M.; Bučar, K.; Bohinc, R.
2012-03-01
A complete in-vacuum curved-crystal x-ray emission spectrometer in Johansson geometry has been constructed for a 2-6 keV energy range with sub natural line-width energy resolution. The spectrometer is designed to measure x-ray emission induced by photon and charged particle impact on solid and gaseous targets. It works with a relatively large x-ray source placed inside the Rowland circle and employs position sensitive detection of diffracted x-rays. Its compact modular design enables fast and easy installation at a synchrotron or particle accelerator beamline. The paper presents main characteristics of the spectrometer and illustrates its capabilities by showing few selected experimental examples.
Kavcic, M.; Budnar, M.; Muehleisen, A.; Gasser, F.; Zitnik, M.; Bucar, K.; Bohinc, R.
2012-03-15
A complete in-vacuum curved-crystal x-ray emission spectrometer in Johansson geometry has been constructed for a 2-6 keV energy range with sub natural line-width energy resolution. The spectrometer is designed to measure x-ray emission induced by photon and charged particle impact on solid and gaseous targets. It works with a relatively large x-ray source placed inside the Rowland circle and employs position sensitive detection of diffracted x-rays. Its compact modular design enables fast and easy installation at a synchrotron or particle accelerator beamline. The paper presents main characteristics of the spectrometer and illustrates its capabilities by showing few selected experimental examples.
Kavčič, M; Budnar, M; Mühleisen, A; Gasser, F; Žitnik, M; Bučar, K; Bohinc, R
2012-03-01
A complete in-vacuum curved-crystal x-ray emission spectrometer in Johansson geometry has been constructed for a 2-6 keV energy range with sub natural line-width energy resolution. The spectrometer is designed to measure x-ray emission induced by photon and charged particle impact on solid and gaseous targets. It works with a relatively large x-ray source placed inside the Rowland circle and employs position sensitive detection of diffracted x-rays. Its compact modular design enables fast and easy installation at a synchrotron or particle accelerator beamline. The paper presents main characteristics of the spectrometer and illustrates its capabilities by showing few selected experimental examples.
Note: Evidence against 2D-Ising criticality in aqueous solutions with added salt
NASA Astrophysics Data System (ADS)
Troncoso, Jacobo; Cerdeiriña, Claudio A.
2013-11-01
Coexistence-curve data in the refractive index-temperature plane for solutions of 3-methyl-pyridine in heavy water with a small amount of added sodium tetraphenylborate have been determined. The analysis of such data indicates that this system belongs to the universality class of the three-dimensional Ising model (3D-Ising). This finding contrasts with previous work by Sadakane et al. [Soft Matter 7, 1334 (2011)] in which 2D-Ising criticality is invoked, but agrees with the recent assessment by Leys et al. [Soft Matter 9, 9326 (2013)].
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.
NASA Astrophysics Data System (ADS)
Uznir, U.; Anton, F.; Suhaibah, A.; Rahman, A. A.; Mioc, D.
2013-09-01
The advantages of three dimensional (3D) city models can be seen in various applications including photogrammetry, urban and regional planning, computer games, etc.. They expand the visualization and analysis capabilities of Geographic Information Systems on cities, and they can be developed using web standards. However, these 3D city models consume much more storage compared to two dimensional (2D) spatial data. They involve extra geometrical and topological information together with semantic data. Without a proper spatial data clustering method and its corresponding spatial data access method, retrieving portions of and especially searching these 3D city models, will not be done optimally. Even though current developments are based on an open data model allotted by the Open Geospatial Consortium (OGC) called CityGML, its XML-based structure makes it challenging to cluster the 3D urban objects. In this research, we propose an opponent data constellation technique of space-filling curves (3D Hilbert curves) for 3D city model data representation. Unlike previous methods, that try to project 3D or n-dimensional data down to 2D or 3D using Principal Component Analysis (PCA) or Hilbert mappings, in this research, we extend the Hilbert space-filling curve to one higher dimension for 3D city model data implementations. The query performance was tested using a CityGML dataset of 1,000 building blocks and the results are presented in this paper. The advantages of implementing space-filling curves in 3D city modeling will improve data retrieval time by means of optimized 3D adjacency, nearest neighbor information and 3D indexing. The Hilbert mapping, which maps a subinterval of the [0, 1] interval to the corresponding portion of the d-dimensional Hilbert's curve, preserves the Lebesgue measure and is Lipschitz continuous. Depending on the applications, several alternatives are possible in order to cluster spatial data together in the third dimension compared to its
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.
Installed Transonic 2D Nozzle Nacelle Boattail Drag Study
NASA Technical Reports Server (NTRS)
Malone, Michael B.; Peavey, Charles C.
1999-01-01
The Transonic Nozzle Boattail Drag Study was initiated in 1995 to develop an understanding of how external nozzle transonic aerodynamics effect airplane performance and how strongly those effects are dependent on nozzle configuration (2D vs. axisymmetric). MDC analyzed the axisymmetric nozzle. Boeing subcontracted Northrop-Grumman to analyze the 2D nozzle. AU participants analyzed the AGARD nozzle as a check-out and validation case. Once the codes were checked out and the gridding resolution necessary for modeling the separated flow in this region determined, the analysis moved to the installed wing/body/nacelle/diverter cases. The boat tail drag validation case was the AGARD B.4 rectangular nozzle. This test case offered both test data and previous CFD analyses for comparison. Results were obtained for test cases B.4.1 (M=0.6) and B.4.2 (M=0.938) and compared very well with the experimental data. Once the validation was complete a CFD grid was constructed for the full Ref. H configuration (wing/body/nacelle/diverter) using a combination of patched and overlapped (Chimera) grids. This was done to ensure that the grid topologies and density would be adequate for the full model. The use of overlapped grids allowed the same grids from the full configuration model to be used for the wing/body alone cases, thus eliminating the risk of grid differences affecting the determination of the installation effects. Once the full configuration model was run and deemed to be suitable the nacelle/diverter grids were removed and the wing/body analysis performed. Reference H wing/body results were completed for M=0.9 (a=0.0, 2.0, 4.0, 6.0 and 8.0), M=1.1 (a=4.0 and 6.0) and M=2.4 (a=0.0, 2.0, 4.4, 6.0 and 8.0). Comparisons of the M=0.9 and M=2.4 cases were made with available wind tunnel data and overall comparisons were good. The axi-inlet/2D nozzle nacelle was analyzed isolated. The isolated nacelle data coupled with the wing/body result enabled the interference effects of the
ERIC Educational Resources Information Center
Nordmark, Arne; Essen, Hanno
2007-01-01
The equilibrium of a flexible inextensible string, or chain, in the centrifugal force field of a rotating reference frame is investigated. It is assumed that the end points are fixed on the rotation axis. The shape of the curve, the skipping rope curve or "troposkien", is given by the Jacobi elliptic function sn. (Contains 3 figures.)
Anodic Polarization Curves Revisited
ERIC Educational Resources Information Center
Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin
2013-01-01
An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…
Memory and visual search in naturalistic 2D and 3D environments
Li, Chia-Ling; Aivar, M. Pilar; Kit, Dmitry M.; Tong, Matthew H.; Hayhoe, Mary M.
2016-01-01
The role of memory in guiding attention allocation in daily behaviors is not well understood. In experiments with two-dimensional (2D) images, there is mixed evidence about the importance of memory. Because the stimulus context in laboratory experiments and daily behaviors differs extensively, we investigated the role of memory in visual search, in both two-dimensional (2D) and three-dimensional (3D) environments. A 3D immersive virtual apartment composed of two rooms was created, and a parallel 2D visual search experiment composed of snapshots from the 3D environment was developed. Eye movements were tracked in both experiments. Repeated searches for geometric objects were performed to assess the role of spatial memory. Subsequently, subjects searched for realistic context objects to test for incidental learning. Our results show that subjects learned the room-target associations in 3D but less so in 2D. Gaze was increasingly restricted to relevant regions of the room with experience in both settings. Search for local contextual objects, however, was not facilitated by early experience. Incidental fixations to context objects do not necessarily benefit search performance. Together, these results demonstrate that memory for global aspects of the environment guides search by restricting allocation of attention to likely regions, whereas task relevance determines what is learned from the active search experience. Behaviors in 2D and 3D environments are comparable, although there is greater use of memory in 3D. PMID:27299769
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.
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.
Designing 2D arrays for SHM of planar structures: a review
NASA Astrophysics Data System (ADS)
Stepinski, Tadeusz; Ambrozinski, Lukasz; Uhl, Tadeusz
2013-04-01
Monitoring structural integrity of large planar structures that aims at detecting and localizing impact or damage at any point of the structure requires normally a relatively dense network of uniformly distributed ultrasonic sensors. 2-D ultrasonic phased arrays, due to their beam-steering capability and all azimuth angle coverage are a very promising tool for structural health monitoring (SHM) of plate-like structures using Lamb waves (LW). Linear phased arrays that have been proposed for that purpose, produce mirrored image characterized by azimuth dependent resolution, which prevents unequivocal damage localization. 2D arrays do not have this drawback and they are even capable of mode selectivity when generating and receiving LWs. Performance of 2D arrays depends on their topology as well as the number of elements (transducers) used and their spacing in terms of wavelength. In this paper we propose a consistent methodology for three-step: theoretical, numerical and experimental investigation of a diversity of 2D array topologies in SHM applications. In the first step, the theoretical evaluation is performed using frequency-dependent structure transfer function (STF). STF that defines linear propagation of different LWs modes through the dispersive medium enables theoretical investigation of the particular array performance for a predefined tone-burst excitation signal. A dedicated software tool has been developed for the numerical evaluation of 2D array directional characteristics (beampattern) in a specific structure. The simulations are performed using local interaction simulation approach (LISA), implemented using NVIDIA CUDA graphical computation unit (GPU), which enables time-efficient 3D simulations of LWs propagation. Beampatterns of a 2D array can be to some extend evaluated analytically and using numerical simulations; in most cases, however, they require experimental verification. Using scanning laser vibrometer is proposed for that purpose, in a setup
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
Antenna coupled detectors for 2D staring focal plane arrays
NASA Astrophysics Data System (ADS)
Gritz, Michael A.; Kolasa, Borys; Lail, Brian; Burkholder, Robert; Chen, Leonard
2013-06-01
Millimeter-wave (mmW)/sub-mmW/THz region of the electro-magnetic spectrum enables imaging thru clothing and other obscurants such as fog, clouds, smoke, sand, and dust. Therefore considerable interest exists in developing low cost millimeter-wave imaging (MMWI) systems. Previous MMWI systems have evolved from crude mechanically scanned, single element receiver systems into very complex multiple receiver camera systems. Initial systems required many expensive mmW integrated-circuit low-noise amplifiers. In order to reduce the cost and complexity of the existing systems, attempts have been made to develop new mmW imaging sensors employing direct detection arrays. In this paper, we report on Raytheon's recent development of a unique focal plane array technology, which operates broadly from the mmW through the sub-mmW/THz region. Raytheon's innovative nano-antenna based detector enables low cost production of 2D staring mmW focal plane arrays (mmW FPA), which not only have equivalent sensitivity and performance to existing MMWI systems, but require no mechanical scanning.
Synthesis and characterization of 2D molybdenum carbide (MXene)
Halim, Joseph; Kota, Sankalp; Lukatskaya, Maria R.; Naguib, Michael; Zhao, Meng -Qiang; Moon, Eun Ju; Pitock, Jeremy; Nanda, Jagjit; May, Steven J.; Gogotsi, Yury; et al
2016-02-17
Large scale synthesis and delamination of 2D Mo2CT x (where T is a surface termination group) has been achieved by selectively etching gallium from the recently discovered nanolaminated, ternary transition metal carbide Mo2Ga2C. Different synthesis and delamination routes result in different flake morphologies. The resistivity of free-standing Mo2CT x films increases by an order of magnitude as the temperature is reduced from 300 to 10 K, suggesting semiconductor-like behavior of this MXene, in contrast to Ti3C2T x which exhibits metallic behavior. At 10 K, the magnetoresistance is positive. Additionally, changes in electronic transport are observed upon annealing of the films.more » When 2 μm thick films are tested as electrodes in supercapacitors, capacitances as high as 700 F cm–3 in a 1 m sulfuric acid electrolyte and high capacity retention for at least 10,000 cycles at 10 A g–1 are obtained. Free-standing Mo2CT x films, with ≈8 wt% carbon nanotubes, perform well when tested as an electrode material for Li-ions, especially at high rates. In conclusion, at 20 and 131 C cycling rates, stable reversible capacities of 250 and 76 mAh g–1, respectively, are achieved for over 1000 cycles.« less
Fracture morphology of 2-D carbon-carbon composition
NASA Technical Reports Server (NTRS)
Avery, W. B.; Herakovich, C. T.
1985-01-01
Out-of-plane tensile tests of a woven fabric carbon-carbon composite were performed in a scanning electron microscope equipped with a tensile stage and a videotape recording system. The composite was prepared from T-300 8-harness satin graphite fabric and a phenolic resin. The (0/90/0/90/0 sub 1/2) sub 2 laminate, with a Theta describing the orientation of the warp fibers of the fabric, was cured at 160 C and pyrolized at 871 C. This was followed by four cycles of resin impregnation, curing, and pyrolysis. A micrograph of the cross section of the composite is presented. Inspection of the specimen fracture surface revealed that the filaments had no residual matrix bonded to them. Further inspection revealed that the fracture was interlaminar in nature. Failure occurred where filaments of adjacent plies had the same orientation. Thus it is postulated that improvement in transverse tensile strength of 2-D carbon-carbon depends on the improvement of the filament-matrix bond strength.
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.
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.
ORION96. 2-d Finite Element Code Postprocessor
Sanford, L.A.; Hallquist, J.O.
1992-02-02
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 forces 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.
High power, high efficiency, 2D laser diode arrays for pumping solid state lasers
Rosenberg, A.; McShea, J.C.; Bogdan, A.R.; Petheram, J.C.; Rosen, A.
1987-11-01
This document reports the current performance of 2D laser diode arrays operating at 770 nm and 808 nm for pumping promethium and neodymium solid state lasers, respectively. Typical power densities are in excess of 2kw/cm/sup 2/ with overall efficiencies greater than 30%.
Generating a 2D Representation of a Complex Data Structure
NASA Technical Reports Server (NTRS)
James, Mark
2006-01-01
A computer program, designed to assist in the development and debugging of other software, generates a two-dimensional (2D) representation of a possibly complex n-dimensional (where n is an integer >2) data structure or abstract rank-n object in that other software. The nature of the 2D representation is such that it can be displayed on a non-graphical output device and distributed by non-graphical means.
Anisotropic 2D Materials for Tunable Hyperbolic Plasmonics.
Nemilentsau, Andrei; Low, Tony; Hanson, George
2016-02-12
Motivated by the recent emergence of a new class of anisotropic 2D materials, we examine their electromagnetic modes and demonstrate that a broad class of the materials can host highly directional hyperbolic plasmons. Their propagation direction can be manipulated on the spot by gate doping, enabling hyperbolic beam reflection, refraction, and bending. The realization of these natural 2D hyperbolic media opens up a new avenue in dynamic control of hyperbolic plasmons not possible in the 3D version.
A simultaneous 2D/3D autostereo workstation
NASA Astrophysics Data System (ADS)
Chau, Dennis; McGinnis, Bradley; Talandis, Jonas; Leigh, Jason; Peterka, Tom; Knoll, Aaron; Sumer, Aslihan; Papka, Michael; Jellinek, Julius
2012-03-01
We present a novel immersive workstation environment that scientists can use for 3D data exploration and as their everyday 2D computer monitor. Our implementation is based on an autostereoscopic dynamic parallax barrier 2D/3D display, interactive input devices, and a software infrastructure that allows client/server software modules to couple the workstation to scientists' visualization applications. This paper describes the hardware construction and calibration, software components, and a demonstration of our system in nanoscale materials science exploration.
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*.
NASA Astrophysics Data System (ADS)
England, J. F.
2006-12-01
Estimates of extreme floods and probabilities are needed in dam safety risk analysis. A multidisciplinary approach was developed to estimate extreme floods that integrated four main elements: radar hydrometeorology, stochastic storm transposition, paleoflood data, and 2d distributed rainfall-runoff modeling. The research focused on developing and applying a two-dimensional, distributed model to simulate extreme floods on the 12,000 km2 Arkansas River above Pueblo, Colorado with return periods up to 10,000 years. The four objectives were to: (1) develop a two-dimensional model suitable for large watersheds (area greater than 2,500 km2); (2) calibrate and validate the model to the June 1921 and May 1894 floods on the Arkansas River; (3) develop a flood frequency curve with the model using the stochastic storm transposition technique; and (4) conduct a sensitivity analysis for initial soil saturation, storm duration and area, and compare the flood frequency curve with gage and paleoflood data. The Two-dimensional Runoff, Erosion and EXport (TREX) model was developed as part of this research. Basin-average rainfall depths and probabilities were estimated using DAD data and stochastic storm transposition with elliptical storms for input to TREX. From these extreme rainstorms, the TREX model was used to estimate a flood frequency curve for this large watershed. Model-generated peak flows were as large as 90,000 to 282,000 ft3/s at Pueblo for 100- to 10,000-year return periods, respectively. Model-generated frequency curves were generally comparable to peak flow and paleoflood data-based frequency curves after radar-based storm location and area limits were applied. The model provides a unique physically-based method for determining flood frequency curves under varied scenarios of antecedent moisture conditions, space and time variability of rainfall and watershed characteristics, and storm center locations.
Chalam, K V; Shah, Vinay A; Tripathi, Ramesh C
2004-01-01
A curved vitrectomy probe for better accessibility of the peripheral retina in phakic eyes is described. The specially designed curved vitrectomy probe has a 20-gauge pneumatic cutter. The radius of curvature at the shaft is 19.4 mm and it is 25 mm long. The ora serrata is accessed through a 3.0- or 4.0-mm sclerotomy in phakic eyes without touching the crystalline lens. Use of this instrument avoids inadvertent trauma to the clear lens in phakic eyes requiring vitreous base excision. This curved vitrectomy instrument complements wide-angle viewing systems and endoscopes for safe surgical treatment of peripheral retinal pathology in phakic eyes. PMID:15185799
Standing sausage modes in curved coronal slabs
NASA Astrophysics Data System (ADS)
Pascoe, D. J.; Nakariakov, V. M.
2016-09-01
Context. Magnetohydrodynamic waveguides such as dense coronal loops can support standing modes. The ratios of the periods of oscillations for different longitudinal harmonics depend on the dispersive nature of the waveguide and so may be used as a seismological tool to determine coronal parameters. Aims: We extend models of standing sausage modes in low β coronal loops to include the effects of loop curvature. The behaviour of standing sausage modes in this geometry is used to explain the properties of observed oscillations that cannot be accounted for using straight loop models. Methods: We perform 2D numerical simulations of an oscillating coronal loop, modelled as a dense slab embedded in a potential magnetic field. The loop is field-aligned and so experiences expansion with height in addition to being curved. Standing sausage modes are excited by compressive perturbations of the loop and their properties are studied. Results: The spatial profiles of standing sausage modes are found to be modified by the expanding loop geometry typical for flaring loops and modelled by a potential magnetic field in our simulations. Longitudinal harmonics of order n > 1 have anti-nodes that are shifted towards the loop apex and the amplitude of anti-nodes near the loop apex is smaller than those near the loop footpoints. Conclusions: We find that the observation of standing sausage modes by the Nobeyama Radioheliograph in a flaring coronal loop on 12 January 2000 is consistent with interpretation in terms of the global mode (n = 1) and third harmonic (n = 3). This interpretation accounts for the period ratio and spatial structure of the observed oscillations.
2D wave-front shaping in optical superlattices using nonlinear volume holography.
Yang, Bo; Hong, Xu-Hao; Lu, Rong-Er; Yue, Yang-Yang; Zhang, Chao; Qin, Yi-Qiang; Zhu, Yong-Yuan
2016-07-01
Nonlinear volume holography is employed to realize arbitrary wave-front shaping during nonlinear processes with properly designed 2D optical superlattices. The concept of a nonlinear polarization wave in nonlinear volume holography is investigated. The holographic imaging of irregular patterns was performed using 2D LiTaO_{3} crystals with fundamental wave propagating along the spontaneous polarization direction, and the results agree well with the theoretical predictions. This Letter not only extends the application area of optical superlattices, but also offers an efficient method for wave-front shaping technology.
Interaction of water molecules with hexagonal 2D systems. A DFT study
NASA Astrophysics Data System (ADS)
Rojas, Ángela; Rey, Rafael
Over the years water sources have been contaminated with many chemical agents, becoming issues that affect health of the world population. The advances of the nanoscience and nanotechnology in the development new materials constitute an alternative for design molecular filters with great efficiencies and low cost for water treatment and purification. In the nanoscale, the process of filtration or separation of inorganic and organic pollutants from water requires to study interactions of these atoms or molecules with different nano-materials. Specifically, it is necessary to understand the role of these interactions in physical and chemical properties of the nano-materials. In this work, the main interest is to do a theoretical study of interaction between water molecules and 2D graphene-like systems, such as silicene (h-Si) or germanene (h-Ge). Using Density Functional Theory we calculate total energy curves as function of separation between of water molecules and 2D systems. Different spatial configurations of water molecules relative to 2D systems are considered. Structural relaxation effects and changes of electronic charge density also are reported. Universidad Nacional de Colombia.
A feasibility study using radiochromic films for fast neutron 2D passive dosimetry
NASA Astrophysics Data System (ADS)
Brady, Samuel L.; Gunasingha, Rathnayaka; Yoshizumi, Terry T.; Howell, Calvin R.; Crowell, Alexander S.; Fallin, Brent; Tonchev, Anton P.; Dewhirst, Mark W.
2010-09-01
The objective of this paper is threefold: (1) to establish sensitivity of XRQA and EBT radiochromic films to fast neutron exposure; (2) to develop a film response to radiation dose calibration curve and (3) to investigate a two-dimensional (2D) film dosimetry technique for use in establishing an experimental setup for a radiobiological irradiation of mice and to assess the dose to the mice in this setup. The films were exposed to a 10 MeV neutron beam via the 2H(d,n)3He reaction. The XRQA film response was a factor of 1.39 greater than EBT film response to the 10 MeV neutron beam when exposed to a neutron dose of 165 cGy. A film response-to-soft tissue dose calibration function was established over a range of 0-10 Gy and had a goodness of fit of 0.9926 with the calibration data. The 2D film dosimetry technique estimated the neutron dose to the mice by measuring the dose using a mouse phantom and by placing a piece of film on the exterior of the experimental mouse setup. The film results were benchmarked using Monte Carlo and aluminum (Al) foil activation measurements. The radiochromic film, Monte Carlo and Al foil dose measurements were strongly correlated, and the film within the mouse phantom agreed to better than 7% of the externally mounted films. These results demonstrated the potential application of radiochromic films for passive 2D neutron dosimetry.
Single-scan 2D NMR: An Emerging Tool in Analytical Spectroscopy
Giraudeau, Patrick; Frydman, Lucio
2016-01-01
Two-dimensional Nuclear Magnetic Resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing an increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago a so-called “ultrafast” (UF) approach was proposed, capable to deliver arbitrary 2D NMR spectra involving any kind of homo- or hetero-nuclear correlations, in a single scan. During the intervening years the performance of this sub-second 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool witnessing an expanded scope of applications. The present reviews summarizes the principles and the main developments which have contributed to the success of this approach, and focuses on applications which have been recently demonstrated in various areas of analytical chemistry –from the real time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications. PMID:25014342
Synthesis, properties and applications of 2D non-graphene materials
NASA Astrophysics Data System (ADS)
Wang, Feng; Wang, Zhenxing; Wang, Qisheng; Wang, Fengmei; Yin, Lei; Xu, Kai; Huang, Yun; He, Jun
2015-07-01
As an emerging class of new materials, two-dimensional (2D) non-graphene materials, including layered and non-layered, and their heterostructures are currently attracting increasing interest due to their promising applications in electronics, optoelectronics and clean energy. In contrast to traditional semiconductors, such as Si, Ge and III-V group materials, 2D materials show significant merits of ultrathin thickness, very high surface-to-volume ratio, and high compatibility with flexible devices. Owing to these unique properties, while scaling down to ultrathin thickness, devices based on these materials as well as artificially synthetic heterostructures exhibit novel and surprising functions and performances. In this review, we aim to provide a summary on the state-of-the-art research activities on 2D non-graphene materials. The scope of the review will cover the preparation of layered and non-layered 2D materials, construction of 2D vertical van der Waals and lateral ultrathin heterostructures, and especially focus on the applications in electronics, optoelectronics and clean energy. Moreover, the review is concluded with some perspectives on the future developments in this field.
Synthesis, properties and applications of 2D non-graphene materials.
Wang, Feng; Wang, Zhenxing; Wang, Qisheng; Wang, Fengmei; Yin, Lei; Xu, Kai; Huang, Yun; He, Jun
2015-07-24
As an emerging class of new materials, two-dimensional (2D) non-graphene materials, including layered and non-layered, and their heterostructures are currently attracting increasing interest due to their promising applications in electronics, optoelectronics and clean energy. In contrast to traditional semiconductors, such as Si, Ge and III-V group materials, 2D materials show significant merits of ultrathin thickness, very high surface-to-volume ratio, and high compatibility with flexible devices. Owing to these unique properties, while scaling down to ultrathin thickness, devices based on these materials as well as artificially synthetic heterostructures exhibit novel and surprising functions and performances. In this review, we aim to provide a summary on the state-of-the-art research activities on 2D non-graphene materials. The scope of the review will cover the preparation of layered and non-layered 2D materials, construction of 2D vertical van der Waals and lateral ultrathin heterostructures, and especially focus on the applications in electronics, optoelectronics and clean energy. Moreover, the review is concluded with some perspectives on the future developments in this field.
Mechanical properties of 2D and 3D braided textile composites
NASA Technical Reports Server (NTRS)
Norman, Timothy L.
1991-01-01
The purpose of this research was to determine the mechanical properties of 2D and 3D braided textile composite materials. Specifically, those designed for tension or shear loading were tested under static loading to failure to investigate the effects of braiding. The overall goal of the work was to provide a structural designer with an idea of how textile composites perform under typical loading conditions. From test results for unnotched tension, it was determined that the 2D is stronger, stiffer, and has higher elongation to failure than the 3D. It was also found that the polyetherether ketone (PEEK) resin system was stronger, stiffer, and had higher elongation at failure than the resin transfer molding (RTM) epoxy. Open hole tension tests showed that PEEK resin is more notch sensitive than RTM epoxy. Of greater significance, it was found that the 3D is less notch sensitive than the 2D. Unnotched compression tests indicated, as did the tension tests, that the 2D is stronger, stiffer, and has higher elongation at failure than the RTM epoxy. The most encouraging results were from compression after impact. The 3D braided composite showed a compression after impact failure stress equal to 92 percent of the unimpacted specimen. The 2D braided composite failed at about 67 percent of the unimpacted specimen. Higher damage tolerance is observed in textiles over conventional composite materials. This is observed in the results, especially in the 3D braided materials.
2D:4D finger ratio positively correlates with total cerebral cortex in males.
Darnai, Gergely; Plózer, Enikő; Perlaki, Gábor; Orsi, Gergely; Nagy, Szilvia Anett; Horváth, Réka; Schwarcz, Attila; Kovács, Norbert; Altbäcker, Anna; Janszky, József; Clemens, Zsófia
2016-02-26
Although there is evidence that the ratio of 2nd-4th digit length (2D:4D) correlates with prenatal testosterone level, psychological and health traits only two studies have assessed the relationship with brain morphological features. Here we investigated the association between the 2D:4D ratio and several brain subvolumes. Seventy-five subjects between the ages of 18 and 30 were included in the study. The length of the 2nd and 4th digits were measured with an electronic vernier caliper while MRI measurements were performed on a Siemens Magnetom Trio Tim (3T) system. Freesurfer software suite was used for volumetric segmentation. Finger ratio significantly positively correlated with total cerebral cortex, total cerebellar white matter and total cerebellar cortex in males but not in females. Our results indicate that prenatal testosterone, as estimated by the 2D:4D ratio has an effect on adult brain morphology in males. PMID:26780566
FRANC2D: A two-dimensional crack propagation simulator. Version 2.7: User's guide
NASA Technical Reports Server (NTRS)
Wawrzynek, Paul; Ingraffea, Anthony
1994-01-01
FRANC 2D (FRacture ANalysis Code, 2 Dimensions) is a menu driven, interactive finite element computer code that performs fracture mechanics analyses of 2-D structures. The code has an automatic mesh generator for triangular and quadrilateral elements. FRANC2D calculates the stress intensity factor using linear elastic fracture mechanics and evaluates crack extension using several methods that may be selected by the user. The code features a mesh refinement and adaptive mesh generation capability that is automatically developed according to the predicted crack extension direction and length. The code also has unique features that permit the analysis of layered structure with load transfer through simulated mechanical fasteners or bonded joints. The code was written for UNIX workstations with X-windows graphics and may be executed on the following computers: DEC DecStation 3000 and 5000 series, IBM RS/6000 series, Hewlitt-Packard 9000/700 series, SUN Sparc stations, and most Silicon Graphics models.
Gravitational Wave Signals from 2D and 3D Core Collapse Supernova Explosions
NASA Astrophysics Data System (ADS)
Yakunin, Konstantin; Mezzacappa, Anthony; Marronetti, Pedro; Bruenn, Stephen; Hix, W. Raphael; Lentz, Eric J.; Messer, O. E. Bronson; Harris, J. Austin; Endeve, Eirik; Blondin, John
2016-03-01
We study two- and three-dimensional (2D and 3D) core-collapse supernovae (CCSN) using our first-principles CCSN simulations performed with the neutrino hydrodynamics code CHIMERA. The following physics is included: Newtonian hydrodynamics with a nuclear equation of state capable of describing matter in both NSE and non-NSE, MGFLD neutrino transport with realistic neutrino interactions, an effective GR gravitational potential, and a nuclear reaction network. Both our 2D and 3D models achieve explosion, which in turn enables us to determine their complete gravitational wave signals. In this talk, we present them, and we analyze the similarities and differences between the 2D and 3D signals.
Spectroscopic investigation of the 3d 2D → nf 2F transitions in lithium
NASA Astrophysics Data System (ADS)
Shahzada, S.; Shah, M.; Haq, S. U.; Nawaz, M.; Ahmed, M.; Nadeem, Ali
2016-05-01
We report term energies and effective quantum numbers of the odd parity 3d 2D → nf 2F series of lithium using multi-step and multi-photon laser excitation schemes. The experiments were performed using three dye lasers simultaneously pumped by the second harmonic (532 nm) of a Q-switched Nd:YAG laser in conjunction with an atomic beam apparatus and thermionic diode ion detector. The first ionization potential of lithium has been determined as 43,487.13 ± 0.02 cm- 1 from the much extended 3d 2D → nf 2F (17 ≤ n ≤ 70) series. In addition, the oscillator strengths of the 3d 2D → nf 2F (15 ≤ n ≤ 48) transitions have been determined, showing a decreasing trend with the increase in principal quantum number n.
NASA Astrophysics Data System (ADS)
Demirci, Stefanie; Kutter, Oliver; Manstad-Hulaas, Frode; Bauernschmitt, Robert; Navab, Nassir
2008-03-01
In the current clinical workflow of minimally invasive aortic procedures navigation tasks are performed under 2D or 3D angiographic imaging. Many solutions for navigation enhancement suggest an integration of the preoperatively acquired computed tomography angiography (CTA) in order to provide the physician with more image information and reduce contrast injection and radiation exposure. This requires exact registration algorithms that align the CTA volume to the intraoperative 2D or 3D images. Additional to the real-time constraint, the registration accuracy should be independent of image dissimilarities due to varying presence of medical instruments and contrast agent. In this paper, we propose efficient solutions for image-based 2D-3D and 3D-3D registration that reduce the dissimilarities by image preprocessing, e.g. implicit detection and segmentation, and adaptive weights introduced into the registration procedure. Experiments and evaluations are conducted on real patient data.
Laser probe for measuring 2-D wave slope spectra of ocean capillary waves.
Palm, C S; Anderson, R C; Reece, A M
1977-04-01
A laser-optical instrument for use in determining the 2-D wave slope spectrum of ocean capillary waves is described. The instrument measures up to a 35 degrees tip angle of the surface normal by measuring the position of a refracted laser beam directed vertically upward through a water surface. A telescope, a continuous 2-D Schottky barrier photodiode, and a pair of analog dividers render the signals independent of water height and insensitive to laser beam intensity fluctuations. Calibration is performed entirely in the laboratory before field use. Sample records and wave slope spectra are shown for 1-D wave tank tests and for 2-D ocean tests. These are presented along with comparison spectra for calm and choppy water conditions. A mechanical wave follower was used to adjust the instrument position in the presence of large ocean swell and tides. PMID:20168638
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 role of head movements in the discrimination of 2-D shape by blind echolocation experts.
Milne, Jennifer L; Goodale, Melvyn A; Thaler, Lore
2014-08-01
Similar to certain bats and dolphins, some blind humans can use sound echoes to perceive their silent surroundings. By producing an auditory signal (e.g., a tongue click) and listening to the returning echoes, these individuals can obtain information about their environment, such as the size, distance, and density of objects. Past research has also hinted at the possibility that blind individuals may be able to use echolocation to gather information about 2-D surface shape, with definite results pending. Thus, here we investigated people's ability to use echolocation to identify the 2-D shape (contour) of objects. We also investigated the role played by head movements--that is, exploratory movements of the head while echolocating--because anecdotal evidence suggests that head movements might be beneficial for shape identification. To this end, we compared the performance of six expert echolocators to that of ten blind nonecholocators and ten blindfolded sighted controls in a shape identification task, with and without head movements. We found that the expert echolocators could use echoes to determine the shapes of the objects with exceptional accuracy when they were allowed to make head movements, but that their performance dropped to chance level when they had to remain still. Neither blind nor blindfolded sighted controls performed above chance, regardless of head movements. Our results show not only that experts can use echolocation to successfully identify 2-D shape, but also that head movements made while echolocating are necessary for the correct identification of 2-D shape. PMID:24874262
Inspection design using 2D phased array, TFM and cueMAP software
McGilp, Ailidh; Dziewierz, Jerzy; Lardner, Tim; Mackersie, John; Gachagan, Anthony
2014-02-18
A simulation suite, cueMAP, has been developed to facilitate the design of inspection processes and sparse 2D array configurations. At the core of cueMAP is a Total Focusing Method (TFM) imaging algorithm that enables computer assisted design of ultrasonic inspection scenarios, including the design of bespoke array configurations to match the inspection criteria. This in-house developed TFM code allows for interactive evaluation of image quality indicators of ultrasonic imaging performance when utilizing a 2D phased array working in FMC/TFM mode. The cueMAP software uses a series of TFM images to build a map of resolution, contrast and sensitivity of imaging performance of a simulated reflector, swept across the inspection volume. The software takes into account probe properties, wedge or water standoff, and effects of specimen curvature. In the validation process of this new software package, two 2D arrays have been evaluated on 304n stainless steel samples, typical of the primary circuit in nuclear plants. Thick section samples have been inspected using a 1MHz 2D matrix array. Due to the processing efficiency of the software, the data collected from these array configurations has been used to investigate the influence sub-aperture operation on inspection performance.
Modeling the impact of spatial relationships on horizontal curve safety.
Findley, Daniel J; Hummer, Joseph E; Rasdorf, William; Zegeer, Charles V; Fowler, Tyler J
2012-03-01
The curved segments of roadways are more hazardous because of the additional centripetalforces exerted on a vehicle, driver expectations, and other factors. The safety of a curve is dependent on various factors, most notably by geometric factors, but the location of a curve in relation to other curves is also thought to influence the safety of those curves because of a driver's expectation to encounter additional curves. The link between an individual curve's geometric characteristics and its safety performance has been established, but spatial considerations are typically not included in a safety analysis. The spatial considerations included in this research consisted of four components: distance to adjacent curves, direction of turn of the adjacent curves, and radius and length of the adjacent curves. The primary objective of this paper is to quantify the spatial relationship between adjacent horizontal curves and horizontal curve safety using a crash modification factor. Doing so enables a safety professional to more accurately estimate safety to allocate funding to reduce or prevent future collisions and more efficiently design new roadway sections to minimize crash risk where there will be a series of curves along a route. The most important finding from this research is the statistical significance of spatial considerations for the prediction of horizontal curve safety. The distances to adjacent curves were found to be a reliable predictor of observed collisions. This research recommends a model which utilizes spatial considerations for horizontal curve safety prediction in addition to current Highway Safety Manual prediction capabilities using individual curve geometric features.
Classification of ASKAP Vast Radio Light Curves
NASA Technical Reports Server (NTRS)
Rebbapragada, Umaa; Lo, Kitty; Wagstaff, Kiri L.; Reed, Colorado; Murphy, Tara; Thompson, David R.
2012-01-01
The VAST survey is a wide-field survey that observes with unprecedented instrument sensitivity (0.5 mJy or lower) and repeat cadence (a goal of 5 seconds) that will enable novel scientific discoveries related to known and unknown classes of radio transients and variables. Given the unprecedented observing characteristics of VAST, it is important to estimate source classification performance, and determine best practices prior to the launch of ASKAP's BETA in 2012. The goal of this study is to identify light curve characterization and classification algorithms that are best suited for archival VAST light curve classification. We perform our experiments on light curve simulations of eight source types and achieve best case performance of approximately 90% accuracy. We note that classification performance is most influenced by light curve characterization rather than classifier algorithm.
Betancur, Julián; Simon, Antoine; Halbert, Edgar; Tavard, François; Carré, François; Hernández, Alfredo; Donal, Erwan; Schnell, Frédéric; Garreau, Mireille
2016-02-01
Describing and analyzing heart multiphysics requires the acquisition and fusion of multisensor cardiac images. Multisensor image fusion enables a combined analysis of these heterogeneous modalities. We propose to register intra-patient multiview 2D+t ultrasound (US) images with multiview late gadolinium-enhanced (LGE) images acquired during cardiac magnetic resonance imaging (MRI), in order to fuse mechanical and tissue state information. The proposed procedure registers both US and LGE to cine MRI. The correction of slice misalignment and the rigid registration of multiview LGE and cine MRI are studied, to select the most appropriate similarity measure. It showed that mutual information performs the best for LGE slice misalignment correction and for LGE and cine registration. Concerning US registration, dynamic endocardial contours resulting from speckle tracking echocardiography were exploited in a geometry-based dynamic registration. We propose the use of an adapted dynamic time warping procedure to synchronize cardiac dynamics in multiview US and cine MRI. The registration of US and LGE MRI was evaluated on a dataset of patients with hypertrophic cardiomyopathy. A visual assessment of 330 left ventricular regions from US images of 28 patients resulted in 92.7% of regions successfully aligned with cardiac structures in LGE. Successfully-aligned regions were then used to evaluate the abilities of strain indicators to predict the presence of fibrosis. Longitudinal peak-strain and peak-delay of aligned left ventricular regions were computed from corresponding regional strain curves from US. The Mann-Withney test proved that the expected values of these indicators change between the populations of regions with and without fibrosis (p < 0.01). ROC curves otherwise proved that the presence of fibrosis is one factor amongst others which modifies longitudinal peak-strain and peak-delay. PMID:26619189
ERIC Educational Resources Information Center
Petscher, Yaacov; Kershaw, Sarah; Koon, Sharon; Foorman, Barbara R.
2014-01-01
Districts and schools use progress monitoring to assess student progress, to identify students who fail to respond to intervention, and to further adapt instruction to student needs. Researchers and practitioners often use progress monitoring data to estimate student achievement growth (slope) and evaluate changes in performance over time for…
ERIC Educational Resources Information Center
Petscher, Yaacov; Kershaw, Sarah; Koon, Sharon; Foorman, Barbara R.
2014-01-01
Districts and schools use progress monitoring to assess student progress, to identify students who fail to respond to intervention, and to further adapt instruction to student needs. Researchers and practitioners often use progress monitoring data to estimate student achievement growth (slope) and evaluate changes in performance over time for…
Al-Jenoobi, F I; Korashy, H M; Ahad, A; Raish, M; Al-Mohizea, A M; Alam, M A; Al-Suwayeh, S A; Alkharfy, K M
2014-11-01
The aim of current study was to investigate the effect of some commonly used medicinal herbs on the regulation of rat CYP2D gene expression and its metabolic activity. Wistar albino rats were treated for seven consecutive days with selected doses of five commonly used herbs (Trigonella foenum-graecum, Ferula asafoetida, Nigella sativa, Commiphora myrrha and Lepidium sativum). Thereafter, rat livers were harvested and CYP2D mRNA levels were determined by RT-PCR. The metabolic activity of CYP2D was performed on rat hepatic microsomes using dextromethorphan as specific substrate. All investigated herbs produced inhibition of CYP2D mRNA expression and metabolic activity. The inhibitory potential of investigated herbs on rat CYP2D mRNA was in the following order: Commiphora myrrha > Nigella sativa > Lepidium sativum > Trigonella foenum-graecum > Ferula asafoetida. Whereas, the inhibitory potential of investigated herbs on CYP2D mediated enzyme metabolic activity was found in following order: Nigella sativa > Lepidium sativum > Trigonella foenum-graecum > Commiphora myrrha > Ferula asafoetida. The current study shows that only used herbs reduce CYP2D activity in rat liver microsomes at the transcriptional levels. Such effects could lead to undesirable pharmacological effects of clinically used low therapeutic index CYP2D substrate drugs.
Are Driving and Overtaking on Right Curves More Dangerous than on Left Curves?
Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar
2010-01-01
It is well known that crashes on horizontal curves are a cause for concern in all countries due to the frequency and severity of crashes at curves compared to road tangents. A recent study of crashes in western Sweden reported a higher rate of crashes in right curves than left curves. To further understand this result, this paper reports the results of novel analyses of the responses of vehicles and drivers during negotiating and overtaking maneuvers on curves for right hand traffic. The overall objectives of the study were to find road parameters for curves that affect vehicle dynamic responses, to analyze these responses during overtaking maneuvers on curves, and to link the results with driver behavior for different curve directions. The studied road features were speed, super-elevation, radius and friction including their interactions, while the analyzed vehicle dynamic factors were lateral acceleration and yaw angular velocity. A simulation program, PC-Crash, has been used to simulate road parameters and vehicle response interaction in curves. Overtaking maneuvers have been simulated for all road feature combinations in a total of 108 runs. Analysis of variances (ANOVA) was performed, using two sided randomized block design, to find differences in vehicle responses for the curve parameters. To study driver response, a field test using an instrumented vehicle and 32 participants was reviewed as it contained longitudinal speed and acceleration data for analysis. The simulation results showed that road features affect overtaking performance in right and left curves differently. Overtaking on right curves was sensitive to radius and the interaction of radius with road condition; while overtaking on left curves was more sensitive to super-elevation. Comparisons of lateral acceleration and yaw angular velocity during these maneuvers showed different vehicle response configurations depending on curve direction and maneuver path. The field test experiments also showed
Are driving and overtaking on right curves more dangerous than on left curves?
Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar
2010-01-01
It is well known that crashes on horizontal curves are a cause for concern in all countries due to the frequency and severity of crashes at curves compared to road tangents. A recent study of crashes in western Sweden reported a higher rate of crashes in right curves than left curves. To further understand this result, this paper reports the results of novel analyses of the responses of vehicles and drivers during negotiating and overtaking maneuvers on curves for right hand traffic. The overall objectives of the study were to find road parameters for curves that affect vehicle dynamic responses, to analyze these responses during overtaking maneuvers on curves, and to link the results with driver behavior for different curve directions. The studied road features were speed, super-elevation, radius and friction including their interactions, while the analyzed vehicle dynamic factors were lateral acceleration and yaw angular velocity. A simulation program, PC-Crash, has been used to simulate road parameters and vehicle response interaction in curves. Overtaking maneuvers have been simulated for all road feature combinations in a total of 108 runs. Analysis of variances (ANOVA) was performed, using two sided randomized block design, to find differences in vehicle responses for the curve parameters. To study driver response, a field test using an instrumented vehicle and 32 participants was reviewed as it contained longitudinal speed and acceleration data for analysis. The simulation results showed that road features affect overtaking performance in right and left curves differently. Overtaking on right curves was sensitive to radius and the interaction of radius with road condition; while overtaking on left curves was more sensitive to super-elevation. Comparisons of lateral acceleration and yaw angular velocity during these maneuvers showed different vehicle response configurations depending on curve direction and maneuver path. The field test experiments also showed
Ultrafast 2D-IR spectroelectrochemistry of flavin mononucleotide
NASA Astrophysics Data System (ADS)
El Khoury, Youssef; Van Wilderen, Luuk J. G. W.; Bredenbeck, Jens
2015-06-01
We demonstrate the coupling of ultrafast two-dimensional infrared (2D-IR) spectroscopy to electrochemistry in solution and apply it to flavin mononucleotide, an important cofactor of redox proteins. For this purpose, we designed a spectroelectrochemical cell optimized for 2D-IR measurements in reflection and measured the time-dependent 2D-IR spectra of the oxidized and reduced forms of flavin mononucleotide. The data show anharmonic coupling and vibrational energy transfer between different vibrational modes in the two redox species. Such information is inaccessible with redox-controlled steady-state FTIR spectroscopy. The wide range of applications offered by 2D-IR spectroscopy, such as sub-picosecond structure determination, IR band assignment via energy transfer, disentangling reaction mixtures through band connectivity in the 2D spectra, and the measurement of solvation dynamics and chemical exchange can now be explored under controlled redox potential. The development of this technique furthermore opens new horizons for studying the dynamics of redox proteins.
Ultrafast 2D-IR spectroelectrochemistry of flavin mononucleotide.
El Khoury, Youssef; Van Wilderen, Luuk J G W; Bredenbeck, Jens
2015-06-01
We demonstrate the coupling of ultrafast two-dimensional infrared (2D-IR) spectroscopy to electrochemistry in solution and apply it to flavin mononucleotide, an important cofactor of redox proteins. For this purpose, we designed a spectroelectrochemical cell optimized for 2D-IR measurements in reflection and measured the time-dependent 2D-IR spectra of the oxidized and reduced forms of flavin mononucleotide. The data show anharmonic coupling and vibrational energy transfer between different vibrational modes in the two redox species. Such information is inaccessible with redox-controlled steady-state FTIR spectroscopy. The wide range of applications offered by 2D-IR spectroscopy, such as sub-picosecond structure determination, IR band assignment via energy transfer, disentangling reaction mixtures through band connectivity in the 2D spectra, and the measurement of solvation dynamics and chemical exchange can now be explored under controlled redox potential. The development of this technique furthermore opens new horizons for studying the dynamics of redox proteins.
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.
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.
A 2 D high accuracy slope measuring system based on a Stitching Shack Hartmann Optical Head.
Idir, Mourad; Kaznatcheev, Konstantine; Dovillaire, Guillaume; Legrand, Jerome; Rungsawang, Rakchanok
2014-02-10
We present a 2D Slope measuring System based on a Stitching Shack Hartmann Optical Head (SSH-OH) aiming to perform high accuracy optical metrology for X-ray mirrors. This system was developed to perform high-accuracy automated metrology for extremely high quality optical components needed for synchrotrons or Free Electrons Lasers (FEL), EUV lithography and x-ray astronomy with slope error accuracy better than 50 nrad rms. PMID:24663568
NASA Astrophysics Data System (ADS)
Jia, Xiaojie; Ai, Bin; Deng, Youjun; Xu, Xinxiang; Peng, Hua; Shen, Hui
2015-08-01
On the basis of perfect PC2D simulation to the measured current density vs voltage (J-V) curve of the best selective emitter (SE) solar cell fabricated by the CSG Company using the screen printing phosphoric paste method, we systematically investigated the effect of the parameters of gridline, base, selective emitter, back surface field (BSF) layer and surface recombination rate on performance of the SE solar cell. Among these parameters, we identified that the base minority carrier lifetime, the front and back surface recombination rate and the ratio of the sheet-resistance of heavily and lightly doped region are the four largest efficiency-affecting factors. If all the parameters have ideal values, the SE solar cell fabricated on a p-type monocrystalline silicon wafer can even obtain the efficiency of 20.45%. In addition, the simulation also shows that fine gridline combining dense gridline and increasing bus bar number while keeping the lower area ratio can offer the other ways to improve the efficiency.
Implicit adaptive mesh refinement for 2D reduced resistive magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Philip, Bobby; Chacón, Luis; Pernice, Michael
2008-10-01
An implicit structured adaptive mesh refinement (SAMR) solver for 2D reduced magnetohydrodynamics (MHD) is described. The time-implicit discretization is able to step over fast normal modes, while the spatial adaptivity resolves thin, dynamically evolving features. A Jacobian-free Newton-Krylov method is used for the nonlinear solver engine. For preconditioning, we have extended the optimal "physics-based" approach developed in [L. Chacón, D.A. Knoll, J.M. Finn, An implicit, nonlinear reduced resistive MHD solver, J. Comput. Phys. 178 (2002) 15-36] (which employed multigrid solver technology in the preconditioner for scalability) to SAMR grids using the well-known Fast Adaptive Composite grid (FAC) method [S. McCormick, Multilevel Adaptive Methods for Partial Differential Equations, SIAM, Philadelphia, PA, 1989]. A grid convergence study demonstrates that the solver performance is independent of the number of grid levels and only depends on the finest resolution considered, and that it scales well with grid refinement. The study of error generation and propagation in our SAMR implementation demonstrates that high-order (cubic) interpolation during regridding, combined with a robustly damping second-order temporal scheme such as BDF2, is required to minimize impact of grid errors at coarse-fine interfaces on the overall error of the computation for this MHD application. We also demonstrate that our implementation features the desired property that the overall numerical error is dependent only on the finest resolution level considered, and not on the base-grid resolution or on the number of refinement levels present during the simulation. We demonstrate the effectiveness of the tool on several challenging problems.
Cascading rainfall uncertainties into 2D inundation impact models
NASA Astrophysics Data System (ADS)
Souvignet, Maxime; de Almeida, Gustavo; Champion, Adrian; Garcia Pintado, Javier; Neal, Jeff; Freer, Jim; Cloke, Hannah; Odoni, Nick; Coxon, Gemma; Bates, Paul; Mason, David
2013-04-01
Existing precipitation products show differences in their spatial and temporal distribution and several studies have presented how these differences influence the ability to predict hydrological responses. However, an atmospheric-hydrologic-hydraulic uncertainty cascade is seldom explored and how, importantly, input uncertainties propagate through this cascade is still poorly understood. Such a project requires a combination of modelling capabilities, runoff generation predictions based on those rainfall forecasts, and hydraulic flood wave propagation based on the runoff predictions. Accounting for uncertainty in each component is important in decision making for issuing flood warnings, monitoring or planning. We suggest a better understanding of uncertainties in inundation impact modelling must consider these differences in rainfall products. This will improve our understanding of the input uncertainties on our predictive capability. In this paper, we propose to address this issue by i) exploring the effects of errors in rainfall on inundation predictive capacity within an uncertainty framework, i.e. testing inundation uncertainty against different comparable meteorological conditions (i.e. using different rainfall products). Our method cascades rainfall uncertainties into a lumped hydrologic model (FUSE) within the GLUE uncertainty framework. The resultant prediction uncertainties in discharge provide uncertain boundary conditions, which are cascaded into a simplified shallow water 2D hydraulic model (LISFLOOD-FP). Rainfall data captured by three different measurement techniques - rain gauges, gridded data and numerical weather predictions (NWP) models are used to assess the combined input data and model parameter uncertainty. The study is performed in the Severn catchment over the period between June and July 2007, where a series of rainfall events causing record floods in the study area). Changes in flood area extent are compared and the uncertainty envelope is
Gálvez, Akemi; Iglesias, Andrés; Cabellos, Luis
2014-01-01
The problem of data fitting is very important in many theoretical and applied fields. In this paper, we consider the problem of optimizing a weighted Bayesian energy functional for data fitting by using global-support approximating curves. By global-support curves we mean curves expressed as a linear combination of basis functions whose support is the whole domain of the problem, as opposed to other common approaches in CAD/CAM and computer graphics driven by piecewise functions (such as B-splines and NURBS) that provide local control of the shape of the curve. Our method applies a powerful nature-inspired metaheuristic algorithm called cuckoo search, introduced recently to solve optimization problems. A major advantage of this method is its simplicity: cuckoo search requires only two parameters, many fewer than other metaheuristic approaches, so the parameter tuning becomes a very simple task. The paper shows that this new approach can be successfully used to solve our optimization problem. To check the performance of our approach, it has been applied to five illustrative examples of different types, including open and closed 2D and 3D curves that exhibit challenging features, such as cusps and self-intersections. Our results show that the method performs pretty well, being able to solve our minimization problem in an astonishingly straightforward way. PMID:24977175
Gálvez, Akemi; Iglesias, Andrés; Cabellos, Luis
2014-01-01
The problem of data fitting is very important in many theoretical and applied fields. In this paper, we consider the problem of optimizing a weighted Bayesian energy functional for data fitting by using global-support approximating curves. By global-support curves we mean curves expressed as a linear combination of basis functions whose support is the whole domain of the problem, as opposed to other common approaches in CAD/CAM and computer graphics driven by piecewise functions (such as B-splines and NURBS) that provide local control of the shape of the curve. Our method applies a powerful nature-inspired metaheuristic algorithm called cuckoo search, introduced recently to solve optimization problems. A major advantage of this method is its simplicity: cuckoo search requires only two parameters, many fewer than other metaheuristic approaches, so the parameter tuning becomes a very simple task. The paper shows that this new approach can be successfully used to solve our optimization problem. To check the performance of our approach, it has been applied to five illustrative examples of different types, including open and closed 2D and 3D curves that exhibit challenging features, such as cusps and self-intersections. Our results show that the method performs pretty well, being able to solve our minimization problem in an astonishingly straightforward way.
Gálvez, Akemi; Iglesias, Andrés; Cabellos, Luis
2014-01-01
The problem of data fitting is very important in many theoretical and applied fields. In this paper, we consider the problem of optimizing a weighted Bayesian energy functional for data fitting by using global-support approximating curves. By global-support curves we mean curves expressed as a linear combination of basis functions whose support is the whole domain of the problem, as opposed to other common approaches in CAD/CAM and computer graphics driven by piecewise functions (such as B-splines and NURBS) that provide local control of the shape of the curve. Our method applies a powerful nature-inspired metaheuristic algorithm called cuckoo search, introduced recently to solve optimization problems. A major advantage of this method is its simplicity: cuckoo search requires only two parameters, many fewer than other metaheuristic approaches, so the parameter tuning becomes a very simple task. The paper shows that this new approach can be successfully used to solve our optimization problem. To check the performance of our approach, it has been applied to five illustrative examples of different types, including open and closed 2D and 3D curves that exhibit challenging features, such as cusps and self-intersections. Our results show that the method performs pretty well, being able to solve our minimization problem in an astonishingly straightforward way. PMID:24977175
Isoperformance curves in applied psychology.
Jones, M B; Kennedy, R S
1996-03-01
Isoperformance is a technique for reading information out of a data-analytic model, comparable to expected mean square or omega squared analyses. It results in a trade-off function (an isoperformance curve) among the determinants of performance. The technique was developed primarily to generate trade-off functions between personnel aptitude and time in training or on the job. However, the technique is general and can be applied in any trade-off situation. In part, the purpose of this paper is to recall the antecedents of isoperformance in psychophysics and to recount the origins and development of the isoperformance readout. Its main purpose, however, is to present several examples of isoperformance curves in applied psychology and to make the case for their usefulness.
Infinite swapping in curved spaces
NASA Astrophysics Data System (ADS)
Curotto, E.; Mella, Massimo
2014-01-01
We develop an extension of the infinite swapping and partial infinite swapping techniques [N. Plattner, J. D. Doll, P. Dupuis, H. Wang, Y. Liu, and J. E. Gubernatis, J. Chem. Phys. 135, 134111 (2011)] to curved spaces. Furthermore, we test the performance of infinite swapping and partial infinite swapping in a series of flat spaces characterized by the same potential energy surface model. We develop a second order variational algorithm for general curved spaces without the extended Lagrangian formalism to include holonomic constraints. We test the new methods by carrying out NVT classical ensemble simulations on a set of multidimensional toroids mapped by stereographic projections and characterized by a potential energy surface built from a linear combination of decoupled double wells shaped purposely to create rare events over a range of temperatures.
Perception-based reversible watermarking for 2D vector maps
NASA Astrophysics Data System (ADS)
Men, Chaoguang; Cao, Liujuan; Li, Xiang
2010-07-01
This paper presents an effective and reversible watermarking approach for digital copyright protection of 2D-vector maps. To ensure that the embedded watermark is insensitive for human perception, we only select the noise non-sensitive regions for watermark embedding by estimating vertex density within each polyline. To ensure the exact recovery of original 2D-vector map after watermark extraction, we introduce a new reversible watermarking scheme based on reversible high-frequency wavelet coefficients modification. Within the former-selected non-sensitive regions, our watermarking operates on the lower-order vertex coordinate decimals with integer wavelet transform. Such operation further reduces the visual distortion caused by watermark embedding. We have validated the effectiveness of our scheme on our real-world city river/building 2D-vector maps. We give extensive experimental comparisons with state-of-the-art methods, including embedding capability, invisibility, and robustness over watermark attacking.
Secretory pathways generating immunosuppressive NKG2D ligands
Baragaño Raneros, Aroa; Suarez-Álvarez, Beatriz; López-Larrea, Carlos
2014-01-01
Natural Killer Group 2 member D (NKG2D) activating receptor, present on the surface of various immune cells, plays an important role in activating the anticancer immune response by their interaction with stress-inducible NKG2D ligands (NKG2DL) on transformed cells. However, cancer cells have developed numerous mechanisms to evade the immune system via the downregulation of NKG2DL from the cell surface, including the release of NKG2DL from the cell surface in a soluble form. Here, we review the mechanisms involved in the production of soluble NKG2DL (sNKG2DL) and the potential therapeutic strategies aiming to block the release of these immunosuppressive ligands. Therapeutically enabling the NKG2D-NKG2DL interaction would promote immunorecognition of malignant cells, thus abrogating disease progression. PMID:25050215
2D bifurcations and Newtonian properties of memristive Chua's circuits
NASA Astrophysics Data System (ADS)
Marszalek, W.; Podhaisky, H.
2016-01-01
Two interesting properties of Chua's circuits are presented. First, two-parameter bifurcation diagrams of Chua's oscillatory circuits with memristors are presented. To obtain various 2D bifurcation images a substantial numerical effort, possibly with parallel computations, is needed. The numerical algorithm is described first and its numerical code for 2D bifurcation image creation is available for free downloading. Several color 2D images and the corresponding 1D greyscale bifurcation diagrams are included. Secondly, Chua's circuits are linked to Newton's law φ ''= F(t,φ,φ')/m with φ=\\text{flux} , constant m > 0, and the force term F(t,φ,φ') containing memory terms. Finally, the jounce scalar equations for Chua's circuits are also discussed.
2D-Raman-THz spectroscopy: a sensitive test of polarizable water models.
Hamm, Peter
2014-11-14
In a recent paper, the experimental 2D-Raman-THz response of liquid water at ambient conditions has been presented [J. Savolainen, S. Ahmed, and P. Hamm, Proc. Natl. Acad. Sci. U. S. A. 110, 20402 (2013)]. Here, all-atom molecular dynamics simulations are performed with the goal to reproduce the experimental results. To that end, the molecular response functions are calculated in a first step, and are then convoluted with the laser pulses in order to enable a direct comparison with the experimental results. The molecular dynamics simulation are performed with several different water models: TIP4P/2005, SWM4-NDP, and TL4P. As polarizability is essential to describe the 2D-Raman-THz response, the TIP4P/2005 water molecules are amended with either an isotropic or a anisotropic polarizability a posteriori after the molecular dynamics simulation. In contrast, SWM4-NDP and TL4P are intrinsically polarizable, and hence the 2D-Raman-THz response can be calculated in a self-consistent way, using the same force field as during the molecular dynamics simulation. It is found that the 2D-Raman-THz response depends extremely sensitively on details of the water model, and in particular on details of the description of polarizability. Despite the limited time resolution of the experiment, it could easily distinguish between various water models. Albeit not perfect, the overall best agreement with the experimental data is obtained for the TL4P water model.
2D-Raman-THz spectroscopy: A sensitive test of polarizable water models
NASA Astrophysics Data System (ADS)
Hamm, Peter
2014-11-01
In a recent paper, the experimental 2D-Raman-THz response of liquid water at ambient conditions has been presented [J. Savolainen, S. Ahmed, and P. Hamm, Proc. Natl. Acad. Sci. U. S. A. 110, 20402 (2013)]. Here, all-atom molecular dynamics simulations are performed with the goal to reproduce the experimental results. To that end, the molecular response functions are calculated in a first step, and are then convoluted with the laser pulses in order to enable a direct comparison with the experimental results. The molecular dynamics simulation are performed with several different water models: TIP4P/2005, SWM4-NDP, and TL4P. As polarizability is essential to describe the 2D-Raman-THz response, the TIP4P/2005 water molecules are amended with either an isotropic or a anisotropic polarizability a posteriori after the molecular dynamics simulation. In contrast, SWM4-NDP and TL4P are intrinsically polarizable, and hence the 2D-Raman-THz response can be calculated in a self-consistent way, using the same force field as during the molecular dynamics simulation. It is found that the 2D-Raman-THz response depends extremely sensitively on details of the water model, and in particular on details of the description of polarizability. Despite the limited time resolution of the experiment, it could easily distinguish between various water models. Albeit not perfect, the overall best agreement with the experimental data is obtained for the TL4P water model.
2D-Raman-THz spectroscopy: A sensitive test of polarizable water models
Hamm, Peter
2014-11-14
In a recent paper, the experimental 2D-Raman-THz response of liquid water at ambient conditions has been presented [J. Savolainen, S. Ahmed, and P. Hamm, Proc. Natl. Acad. Sci. U. S. A. 110, 20402 (2013)]. Here, all-atom molecular dynamics simulations are performed with the goal to reproduce the experimental results. To that end, the molecular response functions are calculated in a first step, and are then convoluted with the laser pulses in order to enable a direct comparison with the experimental results. The molecular dynamics simulation are performed with several different water models: TIP4P/2005, SWM4-NDP, and TL4P. As polarizability is essential to describe the 2D-Raman-THz response, the TIP4P/2005 water molecules are amended with either an isotropic or a anisotropic polarizability a posteriori after the molecular dynamics simulation. In contrast, SWM4-NDP and TL4P are intrinsically polarizable, and hence the 2D-Raman-THz response can be calculated in a self-consistent way, using the same force field as during the molecular dynamics simulation. It is found that the 2D-Raman-THz response depends extremely sensitively on details of the water model, and in particular on details of the description of polarizability. Despite the limited time resolution of the experiment, it could easily distinguish between various water models. Albeit not perfect, the overall best agreement with the experimental data is obtained for the TL4P water model.
Turbulent boundary layer over 2D and 3D large-scale wavy walls
NASA Astrophysics Data System (ADS)
Chamorro, Leonardo P.; Hamed, Ali M.; Castillo, Luciano
2015-11-01
In this work, an experimental investigation of the developing and developed flow over two- and three-dimensional large-scale wavy walls was performed using high-resolution planar particle image velocimetry in a refractive-index-matching flume. The 2D wall is described by a sinusoidal wave in the streamwise direction with amplitude to wavelength ratio a/ λx = 0.05. The 3D wall is defined with an additional wave superimposed on the 2D wall in the spanwise direction with a/ λy = 0.1. The flow was characterized at Reynolds numbers of 4000 and 40000, based on the bulk velocity and the flume half height. Instantaneous velocity fields and time-averaged turbulence quantities reveal strong coupling between large-scale topography and the turbulence dynamics near the wall. Turbulence statistics show the presence of a well-structured shear layer that enhances the turbulence for the 2D wavy wall, whereas the 3D wall exhibits different flow dynamics and significantly lower turbulence levels, particularly for which shows about 30% reduction. The likelihood of recirculation bubbles, levels and spatial distribution of turbulence, and the rate of the turbulent kinetic energy production are shown to be severely affected when a single spanwise mode is superimposed on the 2D wall. POD analysis was also performed to further understand distinctive features of the flow structures due to surface topography.
Single particle 3D reconstruction for 2D crystal images of membrane proteins.
Scherer, Sebastian; Arheit, Marcel; Kowal, Julia; Zeng, Xiangyan; Stahlberg, Henning
2014-03-01
In cases where ultra-flat cryo-preparations of well-ordered two-dimensional (2D) crystals are available, electron crystallography is a powerful method for the determination of the high-resolution structures of membrane and soluble proteins. However, crystal unbending and Fourier-filtering methods in electron crystallography three-dimensional (3D) image processing are generally limited in their performance for 2D crystals that are badly ordered or non-flat. Here we present a single particle image processing approach, which is implemented as an extension of the 2D crystallographic pipeline realized in the 2dx software package, for the determination of high-resolution 3D structures of membrane proteins. The algorithm presented, addresses the low single-to-noise ratio (SNR) of 2D crystal images by exploiting neighborhood correlation between adjacent proteins in the 2D crystal. Compared with conventional single particle processing for randomly oriented particles, the computational costs are greatly reduced due to the crystal-induced limited search space, which allows a much finer search space compared to classical single particle processing. To reduce the considerable computational costs, our software features a hybrid parallelization scheme for multi-CPU clusters and computer with high-end graphic processing units (GPUs). We successfully apply the new refinement method to the structure of the potassium channel MloK1. The calculated 3D reconstruction shows more structural details and contains less noise than the map obtained by conventional Fourier-filtering based processing of the same 2D crystal images.
Assessment and improvement of the 2D/1D method stability in DeCART
Stimpson, S.; Young, M.; Collins, B.; Kelley, B.; Downar, T.
2013-07-01
As part of ongoing work with Consortium for Advanced Simulation of Light Water Reactors (CASL), the 2D/1D code, DeCART, has demonstrated some of the advantages of the 2D/1D method with respect to realistic, full-core analysis, particularly over explicit 3D transport methods, which generally have higher memory and computation requirements. The 2D/1D method performs 2D-radial transport sweeps coupled with ID-axial diffusion calculations to provide a full 3D simulation. DeCART employs the 2D method of characteristics for the radial sweeps and ID one-node nodal diffusion for the axial sweeps, coupling the two methods with transverse leakages to ensure a more consistent representation of the transport equation. It has been observed that refinement of the axial plane thickness leads to instabilities in the calculation scheme. This work assesses the sources of these instabilities and the approaches to improve them, especially with respect to negative scattering cross sections and the tightness of the 2D-radial/ID-axial coupling schemes. Fourier analyses show that the existing iteration scheme is not unconditionally stable, suggesting a tighter coupling scheme is required. For this reason 3D-CMFD has been implemented, among other developments, to ensure more stable calculation. A matrix of test cases has been used to assess the convergence, with the primary parameter being the axial plane thickness, which has been refined down to 1 cm. These cases demonstrate the issues observed and how the modification improve the stability. However, it is apparent that more work is necessary to ensure unconditional stability. (authors)
Optical design of wavelength selective CPVT system with 3D/2D hybrid concentration
NASA Astrophysics Data System (ADS)
Ahmad, N.; Ijiro, T.; Yamada, N.; Kawaguchi, T.; Maemura, T.; Ohashi, H.
2012-10-01
Optical design of a concentrating photovoltaic/thermal (CPVT) system is carried out. Using wavelength-selective optics, the system demonstrates 3-D concentration onto a solar cell and 2-D concentration onto a thermal receiver. Characteristics of the two types of concentrator systems are examined with ray-tracing analysis. The first system is a glazed mirror-based concentrator system mounted on a 2-axis pedestal tracker. The size of the secondary optical element is minimized to decrease the cost of the system, and it has a wavelength-selective function for performing 3-D concentration onto a solar cell and 2-D concentration onto a thermal receiver. The second system is a non-glazed beamdown concentrator system containing parabolic mirrors in the lower part. The beam-down selective mirror performs 3-D concentration onto a solar cell placed above the beam-down selective mirror, and 2-D concentration down to a thermal receiver placed at the bottom level. The system is mounted on a two-axis carousel tracker. A parametric study is performed for those systems with different geometrical 2-D/3-D concentration ratios. Wavelength-selective optics such as hot/cold mirrors and spectrum-splitting technologies are taken into account in the analysis. Results show reduced heat load on the solar cell and increased total system efficiency compared to a non-selective CPV system. Requirements for the wavelength-selective properties are elucidated. It is also shown that the hybrid concept with 2-D concentration onto a thermal receiver and 3-D concentration onto a solar cell has an advantageous geometry because of the high total system efficiency and compatibility with the piping arrangement of the thermal receiver.
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
Quantum process tomography by 2D fluorescence spectroscopy
Pachón, Leonardo A.; Marcus, Andrew H.; Aspuru-Guzik, Alán
2015-06-07
Reconstruction of the dynamics (quantum process tomography) of the single-exciton manifold in energy transfer systems is proposed here on the basis of two-dimensional fluorescence spectroscopy (2D-FS) with phase-modulation. The quantum-process-tomography protocol introduced here benefits from, e.g., the sensitivity enhancement ascribed to 2D-FS. Although the isotropically averaged spectroscopic signals depend on the quantum yield parameter Γ of the doubly excited-exciton manifold, it is shown that the reconstruction of the dynamics is insensitive to this parameter. Applications to foundational and applied problems, as well as further extensions, are discussed.
On 2D bisection method for double eigenvalue problems
Ji, X.
1996-06-01
The two-dimensional bisection method presented in (SIAM J. Matrix Anal. Appl. 13(4), 1085 (1992)) is efficient for solving a class of double eigenvalue problems. This paper further extends the 2D bisection method of full matrix cases and analyses its stability. As in a single parameter case, the 2D bisection method is very stable for the tridiagonal matrix triples satisfying the symmetric-definite condition. Since the double eigenvalue problems arise from two-parameter boundary value problems, an estimate of the discretization error in eigenpairs is also given. Some numerical examples are included. 42 refs., 1 tab.
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.
2012-01-05
Code is for a layered electric medium with 2d structure. Includes air-earth interface at node z=2.. The electric ex and ez fields are calculated on edges of elemental grid and magnetic field hy is calculated on the face of the elemental grid. The code allows for a layered earth with 2d structures. Solutions of coupled first order Maxwell's equations are solved in the two dimensional environment using a finite- difference scheme on a staggered spationamore » and temporal grid.« less
Noninvasive deep Raman detection with 2D correlation analysis
NASA Astrophysics Data System (ADS)
Kim, Hyung Min; Park, Hyo Sun; Cho, Youngho; Jin, Seung Min; Lee, Kang Taek; Jung, Young Mee; Suh, Yung Doug
2014-07-01
The detection of poisonous chemicals enclosed in daily necessaries is prerequisite essential for homeland security with the increasing threat of terrorism. For the detection of toxic chemicals, we combined a sensitive deep Raman spectroscopic method with 2D correlation analysis. We obtained the Raman spectra from concealed chemicals employing spatially offset Raman spectroscopy in which incident line-shaped light experiences multiple scatterings before being delivered to inner component and yielding deep Raman signal. Furthermore, we restored the pure Raman spectrum of each component using 2D correlation spectroscopic analysis with chemical inspection. Using this method, we could elucidate subsurface component under thick powder and packed contents in a bottle.
NASA Astrophysics Data System (ADS)
Hosomichi, Kazuo; Lee, Sungjay
2015-01-01
We study the system of M2-branes suspended between parallel M5-branes using ABJM model with a natural half-BPS boundary condition. For small separation between M5-branes, the worldvolume theory is shown to reduce to a 2D super Yang-Mills theory with some similarity to q-deformed Yang-Mills theory. The gauge coupling is related to the position of the branes in an interesting manner. The theory is considerably different from the 2D theory proposed for multiple "M-strings". We make a detailed comparison of elliptic genus of the two descriptions and find only a partial agreement.
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.
2dF grows up: Echidna for the AAT
NASA Astrophysics Data System (ADS)
McGrath, Andrew; Barden, Sam; Miziarski, Stan; Rambold, William; Smith, Greg
2008-07-01
We present the concept design of a new fibre positioner and spectrograph system for the Anglo-Australian Telescope, as a proposed enhancement to the Anglo-Australian Observatory's well-known 2dF facility. A four-fold multiplex enhancement is accomplished by replacing the 400-fibre 2dF fibre positioning robot with a 1600-fibre Echidna unit, feeding three clones of the AAOmega optical spectrograph. Such a facility has the capability of a redshift 1 survey of a large fraction of the southern sky, collecting five to ten thousand spectra per night for a million-galaxy survey.
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.
Nomenclature for human CYP2D6 alleles.
Daly, A K; Brockmöller, J; Broly, F; Eichelbaum, M; Evans, W E; Gonzalez, F J; Huang, J D; Idle, J R; Ingelman-Sundberg, M; Ishizaki, T; Jacqz-Aigrain, E; Meyer, U A; Nebert, D W; Steen, V M; Wolf, C R; Zanger, U M
1996-06-01
To standardize CYP2D6 allele nomenclature, and to conform with international human gene nomenclature guidelines, an alternative to the current arbitrary system is described. Based on recommendations for human genome nomenclature, we propose that alleles be designated by CYP2D6 followed by an asterisk and a combination of roman letters and arabic numerals distinct for each allele with the number specifying the key mutation and, where appropriate, a letter specifying additional mutations. Criteria for classification as a separate allele and protein nomenclature are also presented. PMID:8807658
Spreading dynamics of 2D dipolar Langmuir monolayer phases.
Heinig, P; Wurlitzer, S; Fischer, Th M
2004-07-01
We study the spreading of a liquid 2D dipolar droplet in a Langmuir monolayer. Interfacial tensions (line tensions) and microscopic contact angles depend on the scale on which they are probed and obey a scaling law. Assuming rapid equilibration of the microscopic contact angle and ideal slippage of the 2D solid/liquid and solid/gas boundary, the driving force of spreading is merely expressed by the shape-dependent long-range interaction integrals. We obtain good agreement between experiment and numerical simulations using this theory. PMID:15278693
Evaluation of 2D ceramic matrix composites in aeroconvective environments
NASA Technical Reports Server (NTRS)
Riccitiello, Salvatore R.; Love, Wendell L.; Balter-Peterson, Aliza
1992-01-01
An evaluation is conducted of a novel ceramic-matrix composite (CMC) material system for use in the aeroconvective-heating environments encountered by the nose caps and wing leading edges of such aerospace vehicles as the Space Shuttle, during orbit-insertion and reentry from LEO. These CMCs are composed of an SiC matrix that is reinforced with Nicalon, Nextel, or carbon refractory fibers in a 2D architecture. The test program conducted for the 2D CMCs gave attention to their subsurface oxidation.
Quantum process tomography by 2D fluorescence spectroscopy
NASA Astrophysics Data System (ADS)
Pachón, Leonardo A.; Marcus, Andrew H.; Aspuru-Guzik, Alán
2015-06-01
Reconstruction of the dynamics (quantum process tomography) of the single-exciton manifold in energy transfer systems is proposed here on the basis of two-dimensional fluorescence spectroscopy (2D-FS) with phase-modulation. The quantum-process-tomography protocol introduced here benefits from, e.g., the sensitivity enhancement ascribed to 2D-FS. Although the isotropically averaged spectroscopic signals depend on the quantum yield parameter Γ of the doubly excited-exciton manifold, it is shown that the reconstruction of the dynamics is insensitive to this parameter. Applications to foundational and applied problems, as well as further extensions, are discussed.
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
Leslie, Mark; Holloway, Charles A
2006-01-01
When a company launches a new product into a new market, the temptation is to immediately ramp up sales force capacity to gain customers as quickly as possible. But hiring a full sales force too early just causes the firm to burn through cash and fail to meet revenue expectations. Before it can sell an innovative product efficiently, the entire organization needs to learn how customers will acquire and use it, a process the authors call the sales learning curve. The concept of a learning curve is well understood in manufacturing. Employees transfer knowledge and experience back and forth between the production line and purchasing, manufacturing, engineering, planning, and operations. The sales learning curve unfolds similarly through the give-and-take between the company--marketing, sales, product support, and product development--and its customers. As customers adopt the product, the firm modifies both the offering and the processes associated with making and selling it. Progress along the manufacturing curve is measured by tracking cost per unit: The more a firm learns about the manufacturing process, the more efficient it becomes, and the lower the unit cost goes. Progress along the sales learning curve is measured in an analogous way: The more a company learns about the sales process, the more efficient it becomes at selling, and the higher the sales yield. As the sales yield increases, the sales learning process unfolds in three distinct phases--initiation, transition, and execution. Each phase requires a different size--and kind--of sales force and represents a different stage in a company's production, marketing, and sales strategies. Adjusting those strategies as the firm progresses along the sales learning curve allows managers to plan resource allocation more accurately, set appropriate expectations, avoid disastrous cash shortfalls, and reduce both the time and money required to turn a profit.
Comparison between 2D and 3D Numerical Modelling of a hot forging simulative test
Croin, M.; Ghiotti, A.; Bruschi, S.
2007-04-07
The paper presents the comparative analysis between 2D and 3D modelling of a simulative experiment, performed in laboratory environment, in which operating conditions approximate hot forging of a turbine aerofoil section. The plane strain deformation was chosen as an ideal case to analyze the process because of the thickness variations in the final section and the consequent distributions of contact pressure and sliding velocity at the interface that are closed to the conditions of the real industrial process. In order to compare the performances of 2D and 3D approaches, two different analyses were performed and compared with the experiments in terms of loads and temperatures peaks at the interface between the dies and the workpiece.
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
Textbook Factor Demand Curves.
ERIC Educational Resources Information Center
Davis, Joe C.
1994-01-01
Maintains that teachers and textbook graphics follow the same basic pattern in illustrating changes in demand curves when product prices increase. Asserts that the use of computer graphics will enable teachers to be more precise in their graphic presentation of price elasticity. (CFR)
ERIC Educational Resources Information Center
Harper, Suzanne R.; Driskell, Shannon
2005-01-01
Graphic tips for using the Geometer's Sketchpad (GSP) are described. The methods to import an image into GSP, define a coordinate system, plot points and curve fit the function using a graphical calculator are demonstrated where the graphic features of GSP allow teachers to expand the use of the technology application beyond the classroom.
ERIC Educational Resources Information Center
Lawes, Jonathan F.
2013-01-01
Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…
ERIC Educational Resources Information Center
Paulton, Richard J. L.
1991-01-01
A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)
Comparing Item Characteristic Curves.
ERIC Educational Resources Information Center
Rosenbaum, Paul R.
1987-01-01
This paper develops and applies three nonparametric comparisons of the shapes of two item characteristic surfaces: (1) proportional latent odds; (2) uniform relative difficulty; and (3) item sensitivity. A method is presented for comparing the relative shapes of two item characteristic curves in two examinee populations who were administered an…
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…
THz devices based on 2D electron systems
NASA Astrophysics Data System (ADS)
Xing, Huili Grace; Yan, Rusen; Song, Bo; Encomendero, Jimy; Jena, Debdeep
2015-05-01
In two-dimensional electron systems with mobility on the order of 1,000 - 10,000 cm2/Vs, the electron scattering time is about 1 ps. For the THz window of 0.3 - 3 THz, the THz photon energy is in the neighborhood of 1 meV, substantially smaller than the optical phonon energy of solids where these 2D electron systems resides. These properties make the 2D electron systems interesting as a platform to realize THz devices. In this paper, I will review 3 approaches investigated in the past few years in my group toward THz devices. The first approach is the conventional high electron mobility transistor based on GaN toward THz amplifiers. The second approach is to employ the tunable intraband absorption in 2D electron systems to realize THz modulators, where I will use graphene as a model material system. The third approach is to exploit plasma wave in these 2D electron systems that can be coupled with a negative differential conductance element for THz amplifiers/sources/detectors.
ELLIPT2D: A Flexible Finite Element Code Written Python
Pletzer, A.; Mollis, J.C.
2001-03-22
The use of the Python scripting language for scientific applications and in particular to solve partial differential equations is explored. It is shown that Python's rich data structure and object-oriented features can be exploited to write programs that are not only significantly more concise than their counter parts written in Fortran, C or C++, but are also numerically efficient. To illustrate this, a two-dimensional finite element code (ELLIPT2D) has been written. ELLIPT2D provides a flexible and easy-to-use framework for solving a large class of second-order elliptic problems. The program allows for structured or unstructured meshes. All functions defining the elliptic operator are user supplied and so are the boundary conditions, which can be of Dirichlet, Neumann or Robbins type. ELLIPT2D makes extensive use of dictionaries (hash tables) as a way to represent sparse matrices.Other key features of the Python language that have been widely used include: operator over loading, error handling, array slicing, and the Tkinter module for building graphical use interfaces. As an example of the utility of ELLIPT2D, a nonlinear solution of the Grad-Shafranov equation is computed using a Newton iterative scheme. A second application focuses on a solution of the toroidal Laplace equation coupled to a magnetohydrodynamic stability code, a problem arising in the context of magnetic fusion research.
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
Proteomic Profiling of Macrophages by 2D Electrophoresis
Bouvet, Marion; Turkieh, Annie; Acosta-Martin, Adelina E.; Chwastyniak, Maggy; Beseme, Olivia; Amouyel, Philippe; Pinet, Florence
2014-01-01
The goal of the two-dimensional (2D) electrophoresis protocol described here is to show how to analyse the phenotype of human cultured macrophages. The key role of macrophages has been shown in various pathological disorders such as inflammatory, immunological, and infectious diseases. In this protocol, we use primary cultures of human monocyte-derived macrophages that can be differentiated into the M1 (pro-inflammatory) or the M2 (anti-inflammatory) phenotype. This in vitro model is reliable for studying the biological activities of M1 and M2 macrophages and also for a proteomic approach. Proteomic techniques are useful for comparing the phenotype and behaviour of M1 and M2 macrophages during host pathogenicity. 2D gel electrophoresis is a powerful proteomic technique for mapping large numbers of proteins or polypeptides simultaneously. We describe the protocol of 2D electrophoresis using fluorescent dyes, named 2D Differential Gel Electrophoresis (DIGE). The M1 and M2 macrophages proteins are labelled with cyanine dyes before separation by isoelectric focusing, according to their isoelectric point in the first dimension, and their molecular mass, in the second dimension. Separated protein or polypeptidic spots are then used to detect differences in protein or polypeptide expression levels. The proteomic approaches described here allows the investigation of the macrophage protein changes associated with various disorders like host pathogenicity or microbial toxins. PMID:25408153
2D signature for detection and identification of drugs
NASA Astrophysics Data System (ADS)
Trofimov, Vyacheslav A.; Varentsova, Svetlana A.; Shen, Jingling; Zhang, Cunlin; Zhou, Qingli; Shi, Yulei
2011-06-01
The method of spectral dynamics analysis (SDA-method) is used for obtaining the2D THz signature of drugs. This signature is used for the detection and identification of drugs with similar Fourier spectra by transmitted THz signal. We discuss the efficiency of SDA method for the identification problem of pure methamphetamine (MA), methylenedioxyamphetamine (MDA), 3, 4-methylenedioxymethamphetamine (MDMA) and Ketamine.
2-D Imaging of Electron Temperature in Tokamak Plasmas
T. Munsat; E. Mazzucato; H. Park; C.W. Domier; M. Johnson; N.C. Luhmann Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol
2004-07-08
By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented.
Melton-Celsa, Angela R; Kokai-Kun, John F; O'Brien, Alison D
2002-01-01
Shiga toxins (Stx) are potent ribosome-inactivating toxins that are produced by Shigella dysenteriae type 1 or certain strains of Escherichia coli. These toxins are composed of one A subunit that can be nicked and reduced to an enzymatically active A1(approximately 27 kDa) and an A2 peptide (approximately 4 kDa) as well as a pentamer of B subunits (approximately 7 kDa/monomer) that binds the eukaryotic cell. Purified Shiga toxin type 2d is activated 10- to 1000-fold for Vero cell toxicity by preincubation with mouse or human intestinal mucus or purified mouse elastase, whereas Stx2, Stx2c, Stx2e and Stx1 are not activatable. E. coli strains that produce the activatable Stx2d are more virulent in a streptomycin (str)-treated mouse model of infection [lethal dose 50% (LD50) = 101] than are E. coli strains that produce any other type of Stx (LD50 = 1010). To identify the element(s) of Stx2d that are required for mucus-mediated activation, toxin genes were constructed such that the expressed mutant toxins consisted of hybrids of Stx2d and Stx1, Stx2 or Stx2e, contained deletions of up to six amino acids from the C-terminus of the A2 of Stx2d or were altered in one or both of the two amino acids of the A2 of Stx2d that represent the only amino acid differences between the activatable Stx2d and the non-activatable Stx2c. Analysis of these mutant toxins revealed that the A2 portion of Stx2d is required for toxin activation and that activation is abrogated if the Stx1 or Stx2e B subunit is substituted for the Stx2d B polypeptide. Furthermore, mass spectrometry performed on buffer- or elastase-treated Stx2d indicated that the A2 peptide of the activated Stx2d was two amino acids smaller than the A2 peptide from buffer-treated Stx2d. This finding, together with the toxin hybrid results, suggests that activation involves B pentamer-dependent cleavage by elastase of the C-terminal two amino acids from the Stx2d A2 peptide.
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
Piecewise power laws in individual learning curves.
Donner, Yoni; Hardy, Joseph L
2015-10-01
The notion that human learning follows a smooth power law (PL) of diminishing gains is well-established in psychology. This characteristic is observed when multiple curves are averaged, potentially masking more complex dynamics underpinning the curves of individual learners. Here, we analyzed 25,280 individual learning curves, each comprising 500 measurements of cognitive performance taken from four cognitive tasks. A piecewise PL (PPL) model explained the individual learning curves significantly better than a single PL, controlling for model complexity. The PPL model allows for multiple PLs connected at different points in the learning process. We also explored the transition dynamics between PL curve component pieces. Performance in later pieces typically surpassed that in earlier pieces, after a brief drop in performance at the transition point. The transition rate was negatively associated with age, even after controlling for overall performance. Our results suggest at least two processes at work in individual learning curves: locally, a gradual, smooth improvement, with diminishing gains within a specific strategy, which is modeled well as a PL; and globally, a discrete sequence of strategy shifts, in which each strategy is better in the long term than the ones preceding it. The piecewise extension of the classic PL of practice has implications for both individual skill acquisition and theories of learning.
Piecewise power laws in individual learning curves.
Donner, Yoni; Hardy, Joseph L
2015-10-01
The notion that human learning follows a smooth power law (PL) of diminishing gains is well-established in psychology. This characteristic is observed when multiple curves are averaged, potentially masking more complex dynamics underpinning the curves of individual learners. Here, we analyzed 25,280 individual learning curves, each comprising 500 measurements of cognitive performance taken from four cognitive tasks. A piecewise PL (PPL) model explained the individual learning curves significantly better than a single PL, controlling for model complexity. The PPL model allows for multiple PLs connected at different points in the learning process. We also explored the transition dynamics between PL curve component pieces. Performance in later pieces typically surpassed that in earlier pieces, after a brief drop in performance at the transition point. The transition rate was negatively associated with age, even after controlling for overall performance. Our results suggest at least two processes at work in individual learning curves: locally, a gradual, smooth improvement, with diminishing gains within a specific strategy, which is modeled well as a PL; and globally, a discrete sequence of strategy shifts, in which each strategy is better in the long term than the ones preceding it. The piecewise extension of the classic PL of practice has implications for both individual skill acquisition and theories of learning. PMID:25711183
Half-metallicity in 2D organometallic honeycomb frameworks
NASA Astrophysics Data System (ADS)
Sun, Hao; Li, Bin; Zhao, Jin
2016-10-01
Half-metallic materials with a high Curie temperature (T C) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d-p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule—CN—noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology.
Half-metallicity in 2D organometallic honeycomb frameworks.
Sun, Hao; Li, Bin; Zhao, Jin
2016-10-26
Half-metallic materials with a high Curie temperature (T C) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d-p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule-CN-noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology.
Half-metallicity in 2D organometallic honeycomb frameworks.
Sun, Hao; Li, Bin; Zhao, Jin
2016-10-26
Half-metallic materials with a high Curie temperature (T C) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d-p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule-CN-noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology. PMID:27541575
Image-based RSA: Roentgen stereophotogrammetric analysis based on 2D-3D image registration.
de Bruin, P W; Kaptein, B L; Stoel, B C; Reiber, J H C; Rozing, P M; Valstar, E R
2008-01-01
Image-based Roentgen stereophotogrammetric analysis (IBRSA) integrates 2D-3D image registration and conventional RSA. Instead of radiopaque RSA bone markers, IBRSA uses 3D CT data, from which digitally reconstructed radiographs (DRRs) are generated. Using 2D-3D image registration, the 3D pose of the CT is iteratively adjusted such that the generated DRRs resemble the 2D RSA images as closely as possible, according to an image matching metric. Effectively, by registering all 2D follow-up moments to the same 3D CT, the CT volume functions as common ground. In two experiments, using RSA and using a micromanipulator as gold standard, IBRSA has been validated on cadaveric and sawbone scapula radiographs, and good matching results have been achieved. The accuracy was: |mu |< 0.083 mm for translations and |mu| < 0.023 degrees for rotations. The precision sigma in x-, y-, and z-direction was 0.090, 0.077, and 0.220 mm for translations and 0.155 degrees , 0.243 degrees , and 0.074 degrees for rotations. Our results show that the accuracy and precision of in vitro IBRSA, performed under ideal laboratory conditions, are lower than in vitro standard RSA but higher than in vivo standard RSA. Because IBRSA does not require radiopaque markers, it adds functionality to the RSA method by opening new directions and possibilities for research, such as dynamic analyses using fluoroscopy on subjects without markers and computer navigation applications.
Modulation of cortical activity in 2D versus 3D virtual reality environments: an EEG study.
Slobounov, Semyon M; Ray, William; Johnson, Brian; Slobounov, Elena; Newell, Karl M
2015-03-01
There is a growing empirical evidence that virtual reality (VR) is valuable for education, training, entertaining and medical rehabilitation due to its capacity to represent real-life events and situations. However, the neural mechanisms underlying behavioral confounds in VR environments are still poorly understood. In two experiments, we examined the effect of fully immersive 3D stereoscopic presentations and less immersive 2D VR environments on brain functions and behavioral outcomes. In Experiment 1 we examined behavioral and neural underpinnings of spatial navigation tasks using electroencephalography (EEG). In Experiment 2, we examined EEG correlates of postural stability and balance. Our major findings showed that fully immersive 3D VR induced a higher subjective sense of presence along with enhanced success rate of spatial navigation compared to 2D. In Experiment 1 power of frontal midline EEG (FM-theta) was significantly higher during the encoding phase of route presentation in the 3D VR. In Experiment 2, the 3D VR resulted in greater postural instability and modulation of EEG patterns as a function of 3D versus 2D environments. The findings support the inference that the fully immersive 3D enriched-environment requires allocation of more brain and sensory resources for cognitive/motor control during both tasks than 2D presentations. This is further evidence that 3D VR tasks using EEG may be a promising approach for performance enhancement and potential applications in clinical/rehabilitation settings. PMID:25448267
Extension and application of the Preissmann slot model to 2D transient mixed flows
NASA Astrophysics Data System (ADS)
Maranzoni, Andrea; Dazzi, Susanna; Aureli, Francesca; Mignosa, Paolo
2015-08-01
This paper presents an extension of the Preissmann slot concept for the modeling of highly transient two-dimensional (2D) mixed flows. The classic conservative formulation of the 2D shallow water equations for free surface flows is adapted by assuming that two fictitious vertical slots, aligned along the two Cartesian plane directions and normally intersecting, are added on the ceiling of each integration element. Accordingly, transitions between free surface and pressurized flow can be handled in a natural and straightforward way by using the same set of governing equations. The opportunity of coupling free surface and pressurized flows is actually useful not only in one-dimensional (1D) problems concerning sewer systems but also for modeling 2D flooding phenomena in which the pressurization of bridges, culverts, or other crossing hydraulic structures can be expected. Numerical simulations are performed by using a shock-capturing MUSCL-Hancock finite volume scheme combined with the FORCE (First-Order Centred) solver for the evaluation of the numerical fluxes. The validation of the mathematical model is accomplished on the basis of both exact solutions of 1D discontinuous initial value problems and reference radial solutions of idealized test cases with cylindrical symmetry. Furthermore, the capability of the model to deal with practical field-scale applications is assessed by simulating the transit of a bore under an arch bridge. Numerical results show that the proposed model is suitable for the prediction of highly transient 2D mixed flows.
Rare Functional Variant in TM2D3 is Associated with Late-Onset Alzheimer's Disease
Grove, Megan L.; Naj, Adam; Vronskaya, Maria; DeStefano, Anita L.; Brody, Jennifer A.; Smith, Albert V.; Amin, Najaf; Sims, Rebecca; Ibrahim-Verbaas, Carla A.; Choi, Seung-Hoan; Lopez, Oscar L.; Beiser, Alexa; Ikram, M. Arfan; Garcia, Melissa E.; Hayward, Caroline; Ripatti, Samuli; Franks, Paul W.; Hallmans, Göran; Rolandsson, Olov; Jansson, Jan-Håkon; Porteous, David J.; Salomaa, Veikko; Eiriksdottir, Gudny; Rice, Kenneth M.; Bellen, Hugo J.; Levy, Daniel; Uitterlinden, Andre G.; Emilsson, Valur; Rotter, Jerome I.; Aspelund, Thor; O’Donnell, Christopher J.; Fitzpatrick, Annette L.; Launer, Lenore J.; Hofman, Albert; Wang, Li-San; Williams, Julie; Schellenberg, Gerard D.; Boerwinkle, Eric; Psaty, Bruce M.; Seshadri, Sudha; Shulman, Joshua M.; Gudnason, Vilmundur; van Duijn, Cornelia M.
2016-01-01
We performed an exome-wide association analysis in 1393 late-onset Alzheimer’s disease (LOAD) cases and 8141 controls from the CHARGE consortium. We found that a rare variant (P155L) in TM2D3 was enriched in Icelanders (~0.5% versus <0.05% in other European populations). In 433 LOAD cases and 3903 controls from the Icelandic AGES sub-study, P155L was associated with increased risk and earlier onset of LOAD [odds ratio (95% CI) = 7.5 (3.5–15.9), p = 6.6x10-9]. Mutation in the Drosophila TM2D3 homolog, almondex, causes a phenotype similar to loss of Notch/Presenilin signaling. Human TM2D3 is capable of rescuing these phenotypes, but this activity is abolished by P155L, establishing it as a functionally damaging allele. Our results establish a rare TM2D3 variant in association with LOAD susceptibility, and together with prior work suggests possible links to the β-amyloid cascade. PMID:27764101
Validation of DYSTOOL for unsteady aerodynamic modeling of 2D airfoils
NASA Astrophysics Data System (ADS)
González, A.; Gomez-Iradi, S.; Munduate, X.
2014-06-01
From the point of view of wind turbine modeling, an important group of tools is based on blade element momentum (BEM) theory using 2D aerodynamic calculations on the blade elements. Due to the importance of this sectional computation of the blades, the National Renewable Wind Energy Center of Spain (CENER) developed DYSTOOL, an aerodynamic code for 2D airfoil modeling based on the Beddoes-Leishman model. The main focus here is related to the model parameters, whose values depend on the airfoil or the operating conditions. In this work, the values of the parameters are adjusted using available experimental or CFD data. The present document is mainly related to the validation of the results of DYSTOOL for 2D airfoils. The results of the computations have been compared with unsteady experimental data of the S809 and NACA0015 profiles. Some of the cases have also been modeled using the CFD code WMB (Wind Multi Block), within the framework of a collaboration with ACCIONA Windpower. The validation has been performed using pitch oscillations with different reduced frequencies, Reynolds numbers, amplitudes and mean angles of attack. The results have shown a good agreement using the methodology of adjustment for the value of the parameters. DYSTOOL have demonstrated to be a promising tool for 2D airfoil unsteady aerodynamic modeling.
Gint2D-T2 correlation NMR of porous media
NASA Astrophysics Data System (ADS)
Zhang, Yan; Blümich, Bernhard
2015-03-01
The internal magnetic field gradient induced in porous media by magnetic susceptibility differences at material interfaces impacts diffusion measurements in particular at high magnetic field and can be used to probe the pore structure. Insight about the relationship between pore space and internal gradient Gint can be obtained from 2D Laplace NMR experiments. When measuring distributions of transverse relaxation times T2 in fluid filled porous media, relaxation and diffusion in internal gradients arise simultaneously and data are often interpreted with the assumption that one or the other parameter be constant throughout the sample. To examine this assumption we measure correlations of the distributions of Gint2D and T2 by 2D Laplace NMR for three different kinds of samples, glass beads with different bead diameters saturated with water, glass beads filled with oil and water, and a wet mortar sample. For the first two samples the cases where either the internal gradient or diffusion dominates were examined separately in order to better understand the relationship between Gint and D. These results are useful for assessing the impact of internal gradients and diffusion in unknown samples, such as the mortar sample. The experiments were performed at different magnetic field strengths corresponding to 300 MHz and 700 MHz 1H Larmor frequency to identify the impact of the magnetic field on the internal gradient. Subsequently, spatially resolved Gint2D-T2 maps were obtained to study the sample heterogeneity.
Gint2D-T2 correlation NMR of porous media.
Zhang, Yan; Blümich, Bernhard
2015-03-01
The internal magnetic field gradient induced in porous media by magnetic susceptibility differences at material interfaces impacts diffusion measurements in particular at high magnetic field and can be used to probe the pore structure. Insight about the relationship between pore space and internal gradient G(int) can be obtained from 2D Laplace NMR experiments. When measuring distributions of transverse relaxation times T(2) in fluid filled porous media, relaxation and diffusion in internal gradients arise simultaneously and data are often interpreted with the assumption that one or the other parameter be constant throughout the sample. To examine this assumption we measure correlations of the distributions of G(int)(2)D and T(2) by 2D Laplace NMR for three different kinds of samples, glass beads with different bead diameters saturated with water, glass beads filled with oil and water, and a wet mortar sample. For the first two samples the cases where either the internal gradient or diffusion dominates were examined separately in order to better understand the relationship between G(int) and D. These results are useful for assessing the impact of internal gradients and diffusion in unknown samples, such as the mortar sample. The experiments were performed at different magnetic field strengths corresponding to 300 MHz and 700 MHz (1)H Larmor frequency to identify the impact of the magnetic field on the internal gradient. Subsequently, spatially resolved Gint(2)D-T(2) maps were obtained to study the sample heterogeneity. PMID:25723135
2D-3D hybrid stabilized finite element method for tsunami runup simulations
NASA Astrophysics Data System (ADS)
Takase, S.; Moriguchi, S.; Terada, K.; Kato, J.; Kyoya, T.; Kashiyama, K.; Kotani, T.
2016-09-01
This paper presents a two-dimensional (2D)-three-dimensional (3D) hybrid stabilized finite element method that enables us to predict a propagation process of tsunami generated in a hypocentral region, which ranges from offshore propagation to runup to urban areas, with high accuracy and relatively low computational costs. To be more specific, the 2D shallow water equation is employed to simulate the propagation of offshore waves, while the 3D Navier-Stokes equation is employed for the runup in urban areas. The stabilized finite element method is utilized for numerical simulations for both of the 2D and 3D domains that are independently discretized with unstructured meshes. The multi-point constraint and transmission methods are applied to satisfy the continuity of flow velocities and pressures at the interface between the resulting 2D and 3D meshes, since neither their spatial dimensions nor node arrangements are consistent. Numerical examples are presented to demonstrate the performance of the proposed hybrid method to simulate tsunami behavior, including offshore propagation and runup to urban areas, with substantially lower computation costs in comparison with full 3D computations.
Voracek, M; Reimer, B; Dressler, S G
2010-12-01
Research particularly focusing on male athletes and popular sports (running and soccer) suggests associations of lower (masculinized) second-to-fourth digit ratio (2D:4D), a putative marker of prenatal androgen action, with better sports performance. Studies focusing on women, non-mainstream sports, or controlling for covariates relevant for sporting success are still sparse. This study examined associations between 2D:4D and performance of both male and female athletes active in fencing (a non-mainstream sport dominated by male participants), while controlling for covariates. National fencing rankings and 2D:4D of 58 male and 41 female Austrian tournament fencers (mean age 24 years) were correlated. Among female, but not male, fencers, lower 2D:4D was related to better national fencing rankings. 2D:4D still accounted for incremental variance (12%) in fencing success, when the effects of salient performance factors (age, body mass index, years of fencing, training intensity, and the personality variables achievement, control, harm avoidance, and social potency) were controlled for (totaling 35% attributable variance). Athletes active in the most aggressive form (the sabre) had lower 2D:4D than those active in the other forms (épée and foil fencing). Sporting success in adult life might be partly prenatally programmed via long-lasting extragenital effects of testosterone. PMID:19843265
A new model for two-dimensional numerical simulation of pseudo-2D gas-solids fluidized beds
Li, Tingwen; Zhang, Yongmin
2013-10-11
Pseudo-two dimensional (pseudo-2D) fluidized beds, for which the thickness of the system is much smaller than the other two dimensions, is widely used to perform fundamental studies on bubble behavior, solids mixing, or clustering phenomenon in different gas-solids fluidization systems. The abundant data from such experimental systems are very useful for numerical model development and validation. However, it has been reported that two-dimensional (2D) computational fluid dynamic (CFD) simulations of pseudo-2D gas-solids fluidized beds usually predict poor quantitative agreement with the experimental data, especially for the solids velocity field. In this paper, a new model is proposed to improve the 2D numerical simulations of pseudo-2D gas-solids fluidized beds by properly accounting for the frictional effect of the front and back walls. Two previously reported pseudo-2D experimental systems were simulated with this model. Compared to the traditional 2D simulations, significant improvements in the numerical predictions have been observed and the predicted results are in better agreement with the available experimental data.
Precision measurement of the 3 d 3/2 2D-state lifetime in a single trapped +40Ca
NASA Astrophysics Data System (ADS)
Shao, H.; Huang, Y.; Guan, H.; Qian, Y.; Gao, K.
2016-10-01
We present a high-precision measurement of the 3 d 3/2 2D-state lifetime in a single trapped +40Ca. The measurement was performed using a high-efficiency quantum-state detection technique to monitor quantum jumps and a high-precision and highly synchronous measurement sequence for laser control. A feature in our measurement is the pumping rate of the 729-nm laser that was corrected in a real-time way. The 3 d 3/2 2D-state lifetime was obtained through the measurement of the spontaneous decay rate after incoherent shelving of the ion to the 3 d 3/2 2D state with a wait time. Systematic errors, such as collisions with background gases, heating effects, impurity components, the shelving and pumping rates, and state detection, were carefully analyzed and estimated. We determined an improved value of the 3 d 3/2 2D-state lifetime to be τ3 /2=1.195 (8 ) s. Furthermore, the 3 d 3/2 2D →4 s 1/2 2S quadrupole transition matrix element was measured to be Sk i=7.936 (26 ) e a02 , and the ratio between the lifetimes of 3 d 2D3 /2 and 3 d 2D5 /2 was determined to be 1.018(11). Our method can be universally applied to lifetime measurements of other single ions and atoms with a similar structure.
Non-linear effects in quantitative 2D NMR of polysaccharides: pitfalls and how to avoid them.
Martineau, Estelle; El Khantache, Kamel; Pupier, Marion; Sepulcri, Patricia; Akoka, Serge; Giraudeau, Patrick
2015-04-10
Quantitative 2D NMR is a powerful analytical tool which is widely used to determine the concentration of small molecules in complex samples. Due to the site-specific response of the 2D NMR signal, the determination of absolute concentrations requires the use of a calibration or standard addition approach, where the analyte acts as its own reference. Standard addition methods, where the targeted sample is gradually spiked with known amounts of the targeted analyte, are particularly well-suited for quantitative 2D NMR of small molecules. This paper explores the potential of such quantitative 2D NMR approaches for the quantitative analysis of a high molecular weight polysaccharide. The results highlight that the standard addition method leads to a strong under-estimation of the target concentration, whatever the 2D NMR pulse sequence. Diffusion measurements show that a change in the macromolecular organization of the studied polysaccharide is the most probable hypothesis to explain the non-linear evolution of the 2D NMR signal with concentration. In spite of this non-linearity--the detailed explanation of which is out of the scope of this paper--we demonstrate that accurate quantitative results can still be obtained provided that an external calibration is performed with a wide range of concentrations surrounding the target value. This study opens the way to a number of studies where 2D NMR is needed for the quantitative analysis of macromolecules.
3-D object recognition using 2-D views.
Li, Wenjing; Bebis, George; Bourbakis, Nikolaos G
2008-11-01
We consider the problem of recognizing 3-D objects from 2-D images using geometric models and assuming different viewing angles and positions. Our goal is to recognize and localize instances of specific objects (i.e., model-based) in a scene. This is in contrast to category-based object recognition methods where the goal is to search for instances of objects that belong to a certain visual category (e.g., faces or cars). The key contribution of our work is improving 3-D object recognition by integrating Algebraic Functions of Views (AFoVs), a powerful framework for predicting the geometric appearance of an object due to viewpoint changes, with indexing and learning. During training, we compute the space of views that groups of object features can produce under the assumption of 3-D linear transformations, by combining a small number of reference views that contain the object features using AFoVs. Unrealistic views (e.g., due to the assumption of 3-D linear transformations) are eliminated by imposing a pair of rigidity constraints based on knowledge of the transformation between the reference views of the object. To represent the space of views that an object can produce compactly while allowing efficient hypothesis generation during recognition, we propose combining indexing with learning in two stages. In the first stage, we sample the space of views of an object sparsely and represent information about the samples using indexing. In the second stage, we build probabilistic models of shape appearance by sampling the space of views of the object densely and learning the manifold formed by the samples. Learning employs the Expectation-Maximization (EM) algorithm and takes place in a "universal," lower-dimensional, space computed through Random Projection (RP). During recognition, we extract groups of point features from the scene and we use indexing to retrieve the most feasible model groups that might have produced them (i.e., hypothesis generation). The likelihood
Miga Aero Actuator and 2D Machined Mechanical Binary Latch
NASA Technical Reports Server (NTRS)
Gummin, Mark A.
2013-01-01
Shape memory alloy (SMA) actuators provide the highest force-to-weight ratio of any known actuator. They can be designed for a wide variety of form factors from flat, thin packages, to form-matching packages for existing actuators. SMA actuators can be operated many thousands of times, so that ground testing is possible. Actuation speed can be accurately controlled from milliseconds to position and hold, and even electronic velocity-profile control is possible. SMA actuators provide a high degree of operational flexibility, and are truly smart actuators capable of being accurately controlled by onboard microprocessors across a wide range of voltages. The Miga Aero actuator is a SMA actuator designed specifically for spaceflight applications. Providing 13 mm of stroke with either 20- or 40-N output force in two different models, the Aero actuator is made from low-outgassing PEEK (polyether ether ketone) plastic, stainless steel, and nickel-titanium SMA wires. The modular actuator weighs less than 28 grams. The dorsal output attachment allows the Aero to be used in either PUSH or PULL modes by inverting the mounting orientation. The SPA1 actuator utilizes commercially available SMA actuator wire to provide 3/8-in. (approx. =.1 cm) of stroke at a force of over 28 lb (approx. = .125 N). The force is provided by a unique packaging of the single SMA wire that provides the output force of four SMA wires mechanically in parallel. The output load is shared by allowing the SMA wire to slip around the output attachment end to adjust or balance the load, preventing any individual wire segment from experiencing high loads during actuation. A built-in end limit switch prevents overheating of the SMA element following actuation when used in conjunction with the Miga Analog Driver [a simple MOSFET (metal oxide semiconductor field-effect transistor) switching circuit]. A simple 2D machined mechanical binary latch has been developed to complement the capabilities of SMA wire
Energy-filtered Electron Transport Structures for Low-power Low-noise 2-D Electronics
Pan, Xuan; Qiu, Wanzhi; Skafidas, Efstratios
2016-01-01
In addition to cryogenic techniques, energy filtering has the potential to achieve high-performance low-noise 2-D electronic systems. Assemblies based on graphene quantum dots (GQDs) have been demonstrated to exhibit interesting transport properties, including resonant tunnelling. In this paper, we investigate GQDs based structures with the goal of producing energy filters for next generation lower-power lower-noise 2-D electronic systems. We evaluate the electron transport properties of the proposed GQD device structures to demonstrate electron energy filtering and the ability to control the position and magnitude of the energy passband by appropriate device dimensioning. We also show that the signal-to-thermal noise ratio performance of the proposed nanoscale device can be modified according to device geometry. The tunability of two-dimensional GQD structures indicates a promising route for the design of electron energy filters to produce low-power and low-noise electronics. PMID:27796343
A Neural-FEM tool for the 2-D magnetic hysteresis modeling
NASA Astrophysics Data System (ADS)
Cardelli, E.; Faba, A.; Laudani, A.; Lozito, G. M.; Riganti Fulginei, F.; Salvini, A.
2016-04-01
The aim of this work is to present a new tool for the analysis of magnetic field problems considering 2-D magnetic hysteresis. In particular, this tool makes use of the Finite Element Method to solve the magnetic field problem in real device, and fruitfully exploits a neural network (NN) for the modeling of 2-D magnetic hysteresis of materials. The NS has as input the magnetic inductions components B at the k-th simulation step and returns as output the corresponding values of the magnetic field H corresponding to the input pattern. It is trained by vector measurements performed on the magnetic material to be modeled. This input/output scheme is directly implemented in a FEM code employing the magnetic potential vector A formulation. Validations through measurements on a real device have been performed.
2D-2D tunneling field-effect transistors using WSe2/SnSe2 heterostructures
NASA Astrophysics Data System (ADS)
Roy, Tania; Tosun, Mahmut; Hettick, Mark; Ahn, Geun Ho; Hu, Chenming; Javey, Ali
2016-02-01
Two-dimensional materials present a versatile platform for developing steep transistors due to their uniform thickness and sharp band edges. We demonstrate 2D-2D tunneling in a WSe2/SnSe2 van der Waals vertical heterojunction device, where WSe2 is used as the gate controlled p-layer and SnSe2 is the degenerately n-type layer. The van der Waals gap facilitates the regulation of band alignment at the heterojunction, without the necessity of a tunneling barrier. ZrO2 is used as the gate dielectric, allowing the scaling of gate oxide to improve device subthreshold swing. Efficient gate control and clean interfaces yield a subthreshold swing of ˜100 mV/dec for >2 decades of drain current at room temperature, hitherto unobserved in 2D-2D tunneling devices. The subthreshold swing is independent of temperature, which is a clear signature of band-to-band tunneling at the heterojunction. A maximum switching ratio ION/IOFF of 107 is obtained. Negative differential resistance in the forward bias characteristics is observed at 77 K. This work bodes well for the possibilities of two-dimensional materials for the realization of energy-efficient future-generation electronics.
NASA Astrophysics Data System (ADS)
Movassaghi, Babak; Rasche, Volker; Viergever, Max A.; Niessen, Wiro J.
2004-05-01
For the diagnosis of ischemic heart disease, accurate quantitative analysis of the coronary arteries is important. In coronary angiography, a number of projections is acquired from which 3D models of the coronaries can be reconstructed. A signifcant limitation of the current 3D modeling procedures is the required user interaction for defining the centerlines of the vessel structures in the 2D projections. Currently, the 3D centerlines of the coronary tree structure are calculated based on the interactively determined centerlines in two projections. For every interactively selected centerline point in a first projection the corresponding point in a second projection has to be determined interactively by the user. The correspondence is obtained based on the epipolar-geometry. In this paper a method is proposed to retrieve all the information required for the modeling procedure, by the interactive determination of the 2D centerline-points in only one projection. For every determined 2D centerline-point the corresponding 3D centerline-point is calculated by the analysis of the 1D gray value functions of the corresponding epipolarlines in space for all available 2D projections. This information is then used to build a 3D representation of the coronary arteries using coronary modeling techniques. The approach is illustrated on the analysis of calibrated phantom and calibrated coronary projection data.
Factorization with genus 2 curves
NASA Astrophysics Data System (ADS)
Cosset, Romain
2010-04-01
The elliptic curve method (ECM) is one of the best factorization methods available. It is possible to use hyperelliptic curves instead of elliptic curves but it is in theory slower. We use special hyperelliptic curves and Kummer surfaces to reduce the complexity of the algorithm. Our implementation GMP-HECM is faster than GMP-ECM for factoring large numbers.
A TVD-type method for 2D scalar Hamilton-Jacobi equations on unstructured meshes
NASA Astrophysics Data System (ADS)
Tang, Lingyan; Song, Songhe
2006-10-01
In this paper, a TVD-type difference scheme which satisfies maximum principle is developed for 2D scalar Hamilton-Jacobi equations on unstructured triangular meshes. The main ideas are node-based approximations and derivative-limited reconstruction with quadratic interpolation polynomial. The solution's slope satisfies maximum principle. Numerical experiments are performed to demonstrate high-order accuracy in smooth fields and good resolution of derivative singularities. The new method is simpler than WENO.
High-Order Spectral Volume Method for 2D Euler Equations
NASA Technical Reports Server (NTRS)
Wang, Z. J.; Zhang, Laiping; Liu, Yen; Kwak, Dochan (Technical Monitor)
2002-01-01
The Spectral Volume (SV) method is extended to the 2D Euler equations. The focus of this paper is to study the performance of the SV method on multidimensional non-linear systems. Implementation details including total variation diminishing (TVD) and total variation bounded (TVB) limiters are presented. Solutions with both smooth features and discontinuities are utilized to demonstrate the overall capability of the SV method.
EDGE2D Simulations of JET{sup 13}C Migration Experiments
J.D. Strachan; J.P. Coad; G. Corrigan; G.F. Matthews; J. Spence
2004-06-16
Material migration has received renewed interest due to tritium retention associated with carbon transport to remote vessel locations. Those results influence the desirability of carbon usage on ITER. Subsequently, additional experiments have been performed, including tracer experiments attempting to identify material migration from specific locations. In this paper, EDGE2D models a well-diagnosed JET{sup 13}C tracer migration experiment. The role of SOL flows upon the migration patterns is identified.
Investigations on the sensitivity of the computer code TURBO-2D
NASA Astrophysics Data System (ADS)
Amon, B.
1994-12-01
The two-dimensional computer model TURBO-2D for the calculation of two-phase flow was used to calculate the cold injection of fuel into a model chamber. Investigations of the influence of the input parameter on its sensitivity relative to the obtained results were made. In addition to that calculations were performed and compared using experimental injection pressure data and corresponding averaged injection parameter.
NASA Astrophysics Data System (ADS)
Brandenburg, J. P.
2013-08-01
Fault-propagation folds form an important trapping element in both onshore and offshore fold-thrust belts, and as such benefit from reliable interpretation. Building an accurate geologic interpretation of such structures requires palinspastic restorations, which are made more challenging by the interplay between folding and faulting. Trishear (Erslev, 1991; Allmendinger, 1998) is a useful tool to unravel this relationship kinematically, but is limited by a restriction to planar fault geometries, or at least planar fault segments. Here, new methods are presented for trishear along continuously curved reverse faults defining a flat-ramp transition. In these methods, rotation of the hanging wall above a curved fault is coupled to translation along a horizontal detachment. Including hanging wall rotation allows for investigation of structures with progressive backlimb rotation. Application of the new algorithms are shown for two fault-propagation fold structures: the Turner Valley Anticline in Southwestern Alberta, and the Alpha Structure in the Niger Delta.
Schulz, Douglas A.
2007-10-08
A biometric system suitable for validating user identity using only mouse movements and no specialized equipment is presented. Mouse curves (mouse movements with little or no pause between them) are individually classied and used to develop classication histograms, which are representative of an individual's typical mouse use. These classication histograms can then be compared to validate identity. This classication approach is suitable for providing continuous identity validation during an entire user session.
Anatomical curve identification
Bowman, Adrian W.; Katina, Stanislav; Smith, Joanna; Brown, Denise
2015-01-01
Methods for capturing images in three dimensions are now widely available, with stereo-photogrammetry and laser scanning being two common approaches. In anatomical studies, a number of landmarks are usually identified manually from each of these images and these form the basis of subsequent statistical analysis. However, landmarks express only a very small proportion of the information available from the images. Anatomically defined curves have the advantage of providing a much richer expression of shape. This is explored in the context of identifying the boundary of breasts from an image of the female torso and the boundary of the lips from a facial image. The curves of interest are characterised by ridges or valleys. Key issues in estimation are the ability to navigate across the anatomical surface in three-dimensions, the ability to recognise the relevant boundary and the need to assess the evidence for the presence of the surface feature of interest. The first issue is addressed by the use of principal curves, as an extension of principal components, the second by suitable assessment of curvature and the third by change-point detection. P-spline smoothing is used as an integral part of the methods but adaptations are made to the specific anatomical features of interest. After estimation of the boundary curves, the intermediate surfaces of the anatomical feature of interest can be characterised by surface interpolation. This allows shape variation to be explored using standard methods such as principal components. These tools are applied to a collection of images of women where one breast has been reconstructed after mastectomy and where interest lies in shape differences between the reconstructed and unreconstructed breasts. They are also applied to a collection of lip images where possible differences in shape between males and females are of interest. PMID:26041943
Li, Guang; Yang, T. Jonathan; Furtado, Hugo; Birkfellner, Wolfgang; Ballangrud, Åse; Powell, Simon N.; Mechalakos, James
2015-01-01
To provide a comprehensive assessment of patient setup accuracy in 6 degrees of freedom (DOFs) using 2-dimensional/3-dimensional (2D/3D) image registration with on-board 2-dimensional kilovoltage (OB-2DkV) radiographic images, we evaluated cranial, head and neck (HN), and thoracic and abdominal sites under clinical conditions. A fast 2D/3D image registration method using graphics processing unit GPU was modified for registration between OB-2DkV and 3D simulation computed tomography (simCT) images, with 3D/3D registration as the gold standard for 6DOF alignment. In 2D/3D registration, body roll rotation was obtained solely by matching orthogonal OB-2DkV images with a series of digitally reconstructed radiographs (DRRs) from simCT with a small rotational increment along the gantry rotation axis. The window/level adjustments for optimal visualization of the bone in OB-2DkV and DRRs were performed prior to registration. Ideal patient alignment at the isocenter was calculated and used as an initial registration position. In 3D/3D registration, cone-beam CT (CBCT) was aligned to simCT on bony structures using a bone density filter in 6DOF. Included in this retrospective study were 37 patients treated in 55 fractions with frameless stereotactic radiosurgery or stereotactic body radiotherapy for cranial and paraspinal cancer. A cranial phantom was used to serve as a control. In all cases, CBCT images were acquired for patient setup with subsequent OB-2DkV verification. It was found that the accuracy of the 2D/3D registration was 0.0 ± 0.5 mm and 0.1° ± 0.4° in phantom. In patient, it is site dependent due to deformation of the anatomy: 0.2 ± 1.6 mm and −0.4° ± 1.2° on average for each dimension for the cranial site, 0.7 ± 1.6 mm and 0.3° ± 1.3° for HN, 0.7 ± 2.0 mm and −0.7° ± 1.1° for the thorax, and 1.1 ± 2.6 mm and −0.5° ± 1.9° for the abdomen. Anatomical deformation and presence of soft tissue in 2D/3D registration affect the consistency with
Generation of spatial orders and space-filling curves.
Schrack, Gunther; Stocco, Leo
2015-06-01
Space-filling curves have been found useful for many applications in diverse fields. A space-filling curve is a path in a 2(r)×2(r) raster domain, which visits each location exactly once. In mathematical terms, space-filling curves linearize a 2D integer space, bijectively mapping the space to the integer line. An algorithm is presented, which generates a large number of space-filling curves/spatial orders. Functions are derived such that the code of each location can be calculated from its coordinates and, conversely, a location code can be decoded to yield the coordinates. The algorithm first generates generate 4×4 spatial orders; they subsequently may be scaled up to any desired domain of size 2(r)×2(r) . The underlying theory of the algorithm, the processes for scaling up, encoding, and decoding are described in detail. The curves are generated as a set of incongruent curves, followed, if required, by the sets of associated congruent curves. A number of space-filling curves are illustrated.
Comparison of 2-D and 3-D estimates of placental volume in early pregnancy.
Aye, Christina Y L; Stevenson, Gordon N; Impey, Lawrence; Collins, Sally L
2015-03-01
Ultrasound estimation of placental volume (PlaV) between 11 and 13 wk has been proposed as part of a screening test for small-for-gestational-age babies. A semi-automated 3-D technique, validated against the gold standard of manual delineation, has been found at this stage of gestation to predict small-for-gestational-age at term. Recently, when used in the third trimester, an estimate obtained using a 2-D technique was found to correlate with placental weight at delivery. Given its greater simplicity, the 2-D technique might be more useful as part of an early screening test. We investigated if the two techniques produced similar results when used in the first trimester. The correlation between PlaV values calculated by the two different techniques was assessed in 139 first-trimester placentas. The agreement on PlaV and derived "standardized placental volume," a dimensionless index correcting for gestational age, was explored with the Mann-Whitney test and Bland-Altman plots. Placentas were categorized into five different shape subtypes, and a subgroup analysis was performed. Agreement was poor for both PlaV and standardized PlaV (p < 0.001 and p < 0.001), with the 2-D technique yielding larger estimates for both indices compared with the 3-D method. The mean difference in standardized PlaV values between the two methods was 0.007 (95% confidence interval: 0.006-0.009). The best agreement was found for regular rectangle-shaped placentas (p = 0.438 and p = 0.408). The poor correlation between the 2-D and 3-D techniques may result from the heterogeneity of placental morphology at this stage of gestation. In early gestation, the simpler 2-D estimates of PlaV do not correlate strongly with those obtained with the validated 3-D technique.
The Impact of Interactivity on Comprehending 2D and 3D Visualizations of Movement Data.
Amini, Fereshteh; Rufiange, Sebastien; Hossain, Zahid; Ventura, Quentin; Irani, Pourang; McGuffin, Michael J
2015-01-01
GPS, RFID, and other technologies have made it increasingly common to track the positions of people and objects over time as they move through two-dimensional spaces. Visualizing such spatio-temporal movement data is challenging because each person or object involves three variables (two spatial variables as a function of the time variable), and simply plotting the data on a 2D geographic map can result in overplotting and occlusion that hides details. This also makes it difficult to understand correlations between space and time. Software such as GeoTime can display such data with a three-dimensional visualization, where the 3rd dimension is used for time. This allows for the disambiguation of spatially overlapping trajectories, and in theory, should make the data clearer. However, previous experimental comparisons of 2D and 3D visualizations have so far found little advantage in 3D visualizations, possibly due to the increased complexity of navigating and understanding a 3D view. We present a new controlled experimental comparison of 2D and 3D visualizations, involving commonly performed tasks that have not been tested before, and find advantages in 3D visualizations for more complex tasks. In particular, we tease out the effects of various basic interactions and find that the 2D view relies significantly on "scrubbing" the timeline, whereas the 3D view relies mainly on 3D camera navigation. Our work helps to improve understanding of 2D and 3D visualizations of spatio-temporal data, particularly with respect to interactivity.
Evaluation of low-dose limits in 3D-2D rigid registration for surgical guidance
NASA Astrophysics Data System (ADS)
Uneri, A.; Wang, A. S.; Otake, Y.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Gallia, G. L.; Gokaslan, Z. L.; Siewerdsen, J. H.
2014-09-01
An algorithm for intensity-based 3D-2D registration of CT and C-arm fluoroscopy is evaluated for use in surgical guidance, specifically considering the low-dose limits of the fluoroscopic x-ray projections. The registration method is based on a framework using the covariance matrix adaptation evolution strategy (CMA-ES) to identify the 3D patient pose that maximizes the gradient information similarity metric. Registration performance was evaluated in an anthropomorphic head phantom emulating intracranial neurosurgery, using target registration error (TRE) to characterize accuracy and robustness in terms of 95% confidence upper bound in comparison to that of an infrared surgical tracking system. Three clinical scenarios were considered: (1) single-view image + guidance, wherein a single x-ray projection is used for visualization and 3D-2D guidance; (2) dual-view image + guidance, wherein one projection is acquired for visualization, combined with a second (lower-dose) projection acquired at a different C-arm angle for 3D-2D guidance; and (3) dual-view guidance, wherein both projections are acquired at low dose for the purpose of 3D-2D guidance alone (not visualization). In each case, registration accuracy was evaluated as a function of the entrance surface dose associated with the projection view(s). Results indicate that images acquired at a dose as low as 4 μGy (approximately one-tenth the dose of a typical fluoroscopic frame) were sufficient to provide TRE comparable or superior to that of conventional surgical tracking, allowing 3D-2D guidance at a level of dose that is at most 10% greater than conventional fluoroscopy (scenario #2) and potentially reducing the dose to approximately 20% of the level in a conventional fluoroscopically guided procedure (scenario #3).
Implications of lack-of-ergodicity in 2D Potts model
NASA Astrophysics Data System (ADS)
Ota, Smita
2015-03-01
Microcanonical Monte Carlo simulation is used to study two dimensional (2D) q state Potts model. We consider a 2D square lattice having NxN spins with periodic boundary condition and simulated the system with N =15 and q =10. The demon energy distribution is found to be exponential for high system energy and large system size. For smaller system size and above the first order transition the demon energy distribution is found to deviate from exp(- βED) and has the form exp(- βED + γ ED2). Here β = 1/kBT and kB is the Boltzmann constant. It is found that γ is finite at higher temperatures. As the system energy is reduced γ becomes zero near the first order transition. It is found that during cooling γ changes sign from negative to positive and then to negative again near the 1st order transition. Therefore the demon energy distribution becomes exp(- βED) (or ergodic) at two values of system energy near the 1st order transition. Further cooling or at still lower temperatures the system shows lack of ergodicity. However, difference in heating cooling curves are apparent in E vs γ. The system energies for which γ is zero during cooling can represent the 'ergodic' states. This can be related to the two-level systems observed in glasses at low temperatures.
Automatic 2D-to-3D image conversion using 3D examples from the internet
NASA Astrophysics Data System (ADS)
Konrad, J.; Brown, G.; Wang, M.; Ishwar, P.; Wu, C.; Mukherjee, D.
2012-03-01
The availability of 3D hardware has so far outpaced the production of 3D content. Although to date many methods have been proposed to convert 2D images to 3D stereopairs, the most successful ones involve human operators and, therefore, are time-consuming and costly, while the fully-automatic ones have not yet achieved the same level of quality. This subpar performance is due to the fact that automatic methods usually rely on assumptions about the captured 3D scene that are often violated in practice. In this paper, we explore a radically different approach inspired by our work on saliency detection in images. Instead of relying on a deterministic scene model for the input 2D image, we propose to "learn" the model from a large dictionary of stereopairs, such as YouTube 3D. Our new approach is built upon a key observation and an assumption. The key observation is that among millions of stereopairs available on-line, there likely exist many stereopairs whose 3D content matches that of the 2D input (query). We assume that two stereopairs whose left images are photometrically similar are likely to have similar disparity fields. Our approach first finds a number of on-line stereopairs whose left image is a close photometric match to the 2D query and then extracts depth information from these stereopairs. Since disparities for the selected stereopairs differ due to differences in underlying image content, level of noise, distortions, etc., we combine them by using the median. We apply the resulting median disparity field to the 2D query to obtain the corresponding right image, while handling occlusions and newly-exposed areas in the usual way. We have applied our method in two scenarios. First, we used YouTube 3D videos in search of the most similar frames. Then, we repeated the experiments on a small, but carefully-selected, dictionary of stereopairs closely matching the query. This, to a degree, emulates the results one would expect from the use of an extremely large 3D
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.
Functionalized 2D atomic sheets with new properties
NASA Astrophysics Data System (ADS)
Sun, Qiang; Zhou, Jian; Wang, Qian; Jena, Puru
2011-03-01
Due to the unique atomic structure and novel physical and chemical properties, graphene has sparked tremendous theoretical and experimental efforts to explore other 2D atomic sheets like B-N, Al-N, and Zn-O, where the two components offer much more complexities and flexibilities in surface modifications. Using First principles calculations based on density functional theory, we have systematically studied the semi- and fully-decorated 2D sheets with H and F and Cl. We have found that the electronic structures and magnetic properties can be effectively tuned, and the system can be a direct or an indirect semiconductor or even a half-metal, and the system can be made ferromagnetic, antiferromagnetic, or magnetically degenerate depending upon how the surface is functionalized. Discussions are made for the possible device applications.
A Better 2-D Mechanical Energy Conservation Experiment
NASA Astrophysics Data System (ADS)
Paesler, Michael
2012-02-01
A variety of simple classical mechanics energy conservation experiments are used in teaching laboratories. Typical one-dimensional (1-D) setups may involve falling balls or oscillating springs. Many of these can be quite satisfying in that students can confirm—within a few percent—that mechanical energy is conserved. Students generally have little trouble identifying discrepancies such as the loss of a few percent of the gravitational potential energy due to air friction encountered by a falling ball. Two-dimensional (2-D) systems can require more sophisticated analysis for higher level laboratories, but such systems often incorporate complicating components that can make the exercise academically incomplete and experimentally less accurate. The following describes a simple 2-D energy conservation experiment based on the popular "Newton's Cradle" toy that allows students to account for nearly all of the mechanical energy in the system in an academically complete analysis.
Defect Dynamics in Active 2D Nematic Liquid Crystals
NASA Astrophysics Data System (ADS)
Decamp, Stephen; Redner, Gabriel; Hagan, Michael; Dogic, Zvonimir
2014-03-01
Active materials are assemblies of animate, energy-consuming objects that exhibit continuous dynamics. As such, they have properties that are dramatically different from those found in conventional materials made of inanimate objects. We present a 2D active nematic liquid crystal composed of bundled microtubules and kinesin motor proteins that exists in a dynamic steady-state far from equilibrium. The active nematic exhibits spontaneous binding and unbinding of charge +1/2 and -1/2 disclination defects as well as streaming of +1/2 defects. By tuning ATP concentration, we precisely control the amount of activity, a key parameter of the system. We characterize the dynamics of streaming defects on a large, flat, 2D interface using quantitative polarization light microscopy. We report fundamental characteristics of the active nematics such as defect velocities, defect creation and annihilation rates, and emergent length scales in the system.
Controlling avalanche criticality in 2D nano arrays.
Zohar, Y C; Yochelis, S; Dahmen, K A; Jung, G; Paltiel, Y
2013-01-01
Many physical systems respond to slowly changing external force through avalanches spanning broad range of sizes. Some systems crackle even without apparent external force, such as bursts of neuronal activity or charge transfer avalanches in 2D molecular layers. Advanced development of theoretical models describing disorder-induced critical phenomena calls for experiments probing the dynamics upon tuneable disorder. Here we show that isomeric structural transitions in 2D organic self-assembled monolayer (SAM) exhibit critical dynamics with experimentally tuneable disorder. The system consists of field effect transistor coupled through SAM to illuminated semiconducting nanocrystals (NCs). Charges photoinduced in NCs are transferred through SAM to the transistor surface and modulate its conductivity. Avalanches of isomeric structural transitions are revealed by measuring the current noise I(t) of the transistor. Accumulated surface traps charges reduce dipole moments of the molecules, decrease their coupling, and thus decrease the critical disorder of the SAM enabling its tuning during experiments.
Visualization of 2-D and 3-D Tensor Fields
NASA Technical Reports Server (NTRS)
Hesselink, Lambertus
1997-01-01
In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyper-streamlines about these points give rise to tri-sector or wedge points. These singularities and their connecting hyper-streamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find , analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.
Visualization of 2-D and 3-D Tensor Fields
NASA Technical Reports Server (NTRS)
Hesselink, Lambertus
1995-01-01
In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyperstreamlines about these points give rise to trisector or wedge points. These singularities and their connecting hyperstreamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find, analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.
2D FEM Heat Transfer & E&M Field Code
1992-04-02
TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation. By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.
2D ice from first principles: structures and phase transitions
NASA Astrophysics Data System (ADS)
Chen, Ji; Schusteritsch, Georg; Pickard, Chris J.; Salzmann, Christoph G.; Michaelides, Angelos
Despite relevance to disparate areas such as cloud microphysics and tribology, major gaps in the understanding of the structures and phase transitions of low-dimensional water ice remain. Here we report a first principles study of confined 2D ice as a function of pressure. We find that at ambient pressure hexagonal and pentagonal monolayer structures are the two lowest enthalpy phases identified. Upon mild compression the pentagonal structure becomes the most stable and persists up to ca. 2 GPa at which point square and rhombic phases are stable. The square phase agrees with recent experimental observations of square ice confined within graphene sheets. We also find a double layer AA stacked square ice phase, which clarifies the difference between experimental observations and earlier force field simulations. This work provides a fresh perspective on 2D confined ice, highlighting the sensitivity of the structures observed to both the confining pressure and width.
2D FEM Heat Transfer & E&M Field Code
1992-04-02
TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation.more » By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.« less