Claw-Free Maximal Planar Graphs

DTIC Science & Technology

1989-01-01

1976, 212-223. 110] M.D. Plummer, On n-extendable graphs, Discrete Math . 31, 1980, 201-210. 1111 , A theorem on matchings in the plane, Graph Theory...in Memory of G.A. Dirac, Ann. Discrete Math . 41, North-Holland, Amsterdam, 1989, 347-354. 1121 N. Sbihi, Algorithme de recherche d’un stable de...cardinalitA maximum dans un graphe sans 6toile, Discrete Math . 29, 1980, 53-76. 1131 D. Sumner, On Tutte’s factorization theorem, Graphs and Combinatorics

Optimization model for UDWDM-PON deployment based on physical restrictions and asymmetric user's clustering

NASA Astrophysics Data System (ADS)

Arévalo, Germán. V.; Hincapié, Roberto C.; Sierra, Javier E.

2015-09-01

UDWDM PON is a leading technology oriented to provide ultra-high bandwidth to final users while profiting the physical channels' capability. One of the main drawbacks of UDWDM technique is the fact that the nonlinear effects, like FWM, become stronger due to the close spectral proximity among channels. This work proposes a model for the optimal deployment of this type of networks taking into account the fiber length limitations imposed by physical restrictions related with the fiber's data transmission as well as the users' asymmetric distribution in a provided region. The proposed model employs the data transmission related effects in UDWDM PON as restrictions in the optimization problem and also considers the user's asymmetric clustering and the subdivision of the users region though a Voronoi geometric partition technique. Here it is considered de Voronoi dual graph, it is the Delaunay Triangulation, as the planar graph for resolving the problem related with the minimum weight of the fiber links.

Extending Matchings in Graphs: A Survey

DTIC Science & Technology

1990-01-01

private communication from, 1989. [11] D.A. Holton, D. Lou and M.D. Plummer, On the 2-extendability of planar graphs, Discrete Math ., (to appear). [12...222. [231 L. Lovasz and M.D. Plummer, Matching Theory, Ann. Discrete Math . 29, North- Holland, Amsterdam, 1986. [241 W.S. Massey, Algebraic Topology...Plummer, On n-extendable graphs, Discrete Math . 31, 1980, 201-210. [341 , Toughness and matching extension in graphs, Discrete Math . 72, 1988, 311-320

The stationary sine-Gordon equation on metric graphs: Exact analytical solutions for simple topologies

NASA Astrophysics Data System (ADS)

Sabirov, K.; Rakhmanov, S.; Matrasulov, D.; Susanto, H.

2018-04-01

We consider the stationary sine-Gordon equation on metric graphs with simple topologies. Exact analytical solutions are obtained for different vertex boundary conditions. It is shown that the method can be extended for tree and other simple graph topologies. Applications of the obtained results to branched planar Josephson junctions and Josephson junctions with tricrystal boundaries are discussed.

Finding minimum-quotient cuts in planar graphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.K.; Phillips, C.A.

Given a graph G = (V, E) where each vertex v {element_of} V is assigned a weight w(v) and each edge e {element_of} E is assigned a cost c(e), the quotient of a cut partitioning the vertices of V into sets S and {bar S} is c(S, {bar S})/min{l_brace}w(S), w(S){r_brace}, where c(S, {bar S}) is the sum of the costs of the edges crossing the cut and w(S) and w({bar S}) are the sum of the weights of the vertices in S and {bar S}, respectively. The problem of finding a cut whose quotient is minimum for a graph hasmore » in recent years attracted considerable attention, due in large part to the work of Rao and Leighton and Rao. They have shown that an algorithm (exact or approximation) for the minimum-quotient-cut problem can be used to obtain an approximation algorithm for the more famous minimumb-balanced-cut problem, which requires finding a cut (S,{bar S}) minimizing c(S,{bar S}) subject to the constraint bW {le} w(S) {le} (1 {minus} b)W, where W is the total vertex weight and b is some fixed balance in the range 0 < b {le} {1/2}. Unfortunately, the minimum-quotient-cut problem is strongly NP-hard for general graphs, and the best polynomial-time approximation algorithm known for the general problem guarantees only a cut whose quotient is at mostO(lg n) times optimal, where n is the size of the graph. However, for planar graphs, the minimum-quotient-cut problem appears more tractable, as Rao has developed several efficient approximation algorithms for the planar version of the problem capable of finding a cut whose quotient is at most some constant times optimal. In this paper, we improve Rao`s algorithms, both in terms of accuracy and speed. As our first result, we present two pseudopolynomial-time exact algorithms for the planar minimum-quotient-cut problem. As Rao`s most accurate approximation algorithm for the problem -- also a pseudopolynomial-time algorithm -- guarantees only a 1.5-times-optimal cut, our algorithms represent a significant advance.« less

Finding minimum-quotient cuts in planar graphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.K.; Phillips, C.A.

Given a graph G = (V, E) where each vertex v [element of] V is assigned a weight w(v) and each edge e [element of] E is assigned a cost c(e), the quotient of a cut partitioning the vertices of V into sets S and [bar S] is c(S, [bar S])/min[l brace]w(S), w(S)[r brace], where c(S, [bar S]) is the sum of the costs of the edges crossing the cut and w(S) and w([bar S]) are the sum of the weights of the vertices in S and [bar S], respectively. The problem of finding a cut whose quotient is minimummore » for a graph has in recent years attracted considerable attention, due in large part to the work of Rao and Leighton and Rao. They have shown that an algorithm (exact or approximation) for the minimum-quotient-cut problem can be used to obtain an approximation algorithm for the more famous minimumb-balanced-cut problem, which requires finding a cut (S,[bar S]) minimizing c(S,[bar S]) subject to the constraint bW [le] w(S) [le] (1 [minus] b)W, where W is the total vertex weight and b is some fixed balance in the range 0 < b [le] [1/2]. Unfortunately, the minimum-quotient-cut problem is strongly NP-hard for general graphs, and the best polynomial-time approximation algorithm known for the general problem guarantees only a cut whose quotient is at mostO(lg n) times optimal, where n is the size of the graph. However, for planar graphs, the minimum-quotient-cut problem appears more tractable, as Rao has developed several efficient approximation algorithms for the planar version of the problem capable of finding a cut whose quotient is at most some constant times optimal. In this paper, we improve Rao's algorithms, both in terms of accuracy and speed. As our first result, we present two pseudopolynomial-time exact algorithms for the planar minimum-quotient-cut problem. As Rao's most accurate approximation algorithm for the problem -- also a pseudopolynomial-time algorithm -- guarantees only a 1.5-times-optimal cut, our algorithms represent a significant advance.« less

Correlation based networks of equity returns sampled at different time horizons

NASA Astrophysics Data System (ADS)

Tumminello, M.; di Matteo, T.; Aste, T.; Mantegna, R. N.

2007-01-01

We investigate the planar maximally filtered graphs of the portfolio of the 300 most capitalized stocks traded at the New York Stock Exchange during the time period 2001 2003. Topological properties such as the average length of shortest paths, the betweenness and the degree are computed on different planar maximally filtered graphs generated by sampling the returns at different time horizons ranging from 5 min up to one trading day. This analysis confirms that the selected stocks compose a hierarchical system progressively structuring as the sampling time horizon increases. Finally, a cluster formation, associated to economic sectors, is quantitatively investigated.

The geometry of on-shell diagrams

NASA Astrophysics Data System (ADS)

Franco, Sebastián; Galloni, Daniele; Mariotti, Alberto

2014-08-01

The fundamental role of on-shell diagrams in quantum field theory has been recently recognized. On-shell diagrams, or equivalently bipartite graphs, provide a natural bridge connecting gauge theory to powerful mathematical structures such as the Grassmannian. We perform a detailed investigation of the combinatorial and geometric objects associated to these graphs. We mainly focus on their relation to polytopes and toric geometry, the Grassmannian and its stratification. Our work extends the current understanding of these connections along several important fronts, most notably eliminating restrictions imposed by planarity, positivity, reducibility and edge removability. We illustrate our ideas with several explicit examples and introduce concrete methods that considerably simplify computations. We consider it highly likely that the structures unveiled in this article will arise in the on-shell study of scattering amplitudes beyond the planar limit. Our results can be conversely regarded as an expansion in the understanding of the Grassmannian in terms of bipartite graphs.

Arabidopsis  SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity.

PubMed

Pietra, Stefano; Gustavsson, Anna; Kiefer, Christian; Kalmbach, Lothar; Hörstedt, Per; Ikeda, Yoshihisa; Stepanova, Anna N; Alonso, Jose M; Grebe, Markus

2013-01-01

The orientation of cell division and the coordination of cell polarity within the plane of the tissue layer (planar polarity) contribute to shape diverse multicellular organisms. The root of Arabidopsis thaliana displays regularly oriented cell divisions, cell elongation and planar polarity providing a plant model system to study these processes. Here we report that the SABRE protein, which shares similarity with proteins of unknown function throughout eukaryotes, has important roles in orienting cell division and planar polarity. SABRE localizes at the plasma membrane, endomembranes, mitotic spindle and cell plate. SABRE stabilizes the orientation of CLASP-labelled preprophase band microtubules predicting the cell division plane, and of cortical microtubules driving cell elongation. During planar polarity establishment, sabre is epistatic to clasp at directing polar membrane domains of Rho-of-plant GTPases. Our findings mechanistically link SABRE to CLASP-dependent microtubule organization, shedding new light on the function of SABRE-related proteins in eukaryotes.

Computational Study for Planar Connected Dominating Set Problem

NASA Astrophysics Data System (ADS)

Marzban, Marjan; Gu, Qian-Ping; Jia, Xiaohua

The connected dominating set (CDS) problem is a well studied NP-hard problem with many important applications. Dorn et al. [ESA2005, LNCS3669,pp95-106] introduce a new technique to generate 2^{O(sqrt{n})} time and fixed-parameter algorithms for a number of non-local hard problems, including the CDS problem in planar graphs. The practical performance of this algorithm is yet to be evaluated. We perform a computational study for such an evaluation. The results show that the size of instances can be solved by the algorithm mainly depends on the branchwidth of the instances, coinciding with the theoretical result. For graphs with small or moderate branchwidth, the CDS problem instances with size up to a few thousands edges can be solved in a practical time and memory space. This suggests that the branch-decomposition based algorithms can be practical for the planar CDS problem.

Genus Ranges of 4-Regular Rigid Vertex Graphs

PubMed Central

Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin

2016-01-01

A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2n vertices (n > 1), we prove that all intervals [a, b] for all a < b ≤ n, and singletons [h, h] for some h ≤ n, are realized as genus ranges. For graphs with 2n − 1 vertices (n ≥ 1), we prove that all intervals [a, b] for all a < b ≤ n except [0, n], and [h, h] for some h ≤ n, are realized as genus ranges. We also provide constructions of graphs that realize these ranges. PMID:27807395

An efficient algorithm for planar drawing of RNA structures with pseudoknots of any type.

PubMed

Byun, Yanga; Han, Kyungsook

2016-06-01

An RNA pseudoknot is a tertiary structural element in which bases of a loop pair with complementary bases are outside the loop. A drawing of RNA secondary structures is a tree, but a drawing of RNA pseudoknots is a graph that has an inner cycle within a pseudoknot and possibly outer cycles formed between the pseudoknot and other structural elements. Visualizing a large-scale RNA structure with pseudoknots as a planar drawing is challenging because a planar drawing of an RNA structure requires both pseudoknots and an entire structure enclosing the pseudoknots to be embedded into a plane without overlapping or crossing. This paper presents an efficient heuristic algorithm for visualizing a pseudoknotted RNA structure as a planar drawing. The algorithm consists of several parts for finding crossing stems and page mapping the stems, for the layout of stem-loops and pseudoknots, and for overlap detection between structural elements and resolving it. Unlike previous algorithms, our algorithm generates a planar drawing for a large RNA structure with pseudoknots of any type and provides a bracket view of the structure. It generates a compact and aesthetic structure graph for a large pseudoknotted RNA structure in O([Formula: see text]) time, where n is the number of stems of the RNA structure.

Arabidopsis  SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity

PubMed Central

Pietra, Stefano; Gustavsson, Anna; Kiefer, Christian; Kalmbach, Lothar; Hörstedt, Per; Ikeda, Yoshihisa; Stepanova, Anna N.; Alonso, Jose M.; Grebe, Markus

2013-01-01

The orientation of cell division and the coordination of cell polarity within the plane of the tissue layer (planar polarity) contribute to shape diverse multicellular organisms. The root of Arabidopsis thaliana displays regularly oriented cell divisions, cell elongation and planar polarity providing a plant model system to study these processes. Here we report that the SABRE protein, which shares similarity with proteins of unknown function throughout eukaryotes, has important roles in orienting cell division and planar polarity. SABRE localizes at the plasma membrane, endomembranes, mitotic spindle and cell plate. SABRE stabilizes the orientation of CLASP-labelled preprophase band microtubules predicting the cell division plane, and of cortical microtubules driving cell elongation. During planar polarity establishment, sabre is epistatic to clasp at directing polar membrane domains of Rho-of-plant GTPases. Our findings mechanistically link SABRE to CLASP-dependent microtubule organization, shedding new light on the function of SABRE-related proteins in eukaryotes. PMID:24240534

Truncated Long-Range Percolation on Oriented Graphs

NASA Astrophysics Data System (ADS)

van Enter, A. C. D.; de Lima, B. N. B.; Valesin, D.

2016-07-01

We consider different problems within the general theme of long-range percolation on oriented graphs. Our aim is to settle the so-called truncation question, described as follows. We are given probabilities that certain long-range oriented bonds are open; assuming that the sum of these probabilities is infinite, we ask if the probability of percolation is positive when we truncate the graph, disallowing bonds of range above a possibly large but finite threshold. We give some conditions in which the answer is affirmative. We also translate some of our results on oriented percolation to the context of a long-range contact process.

Approximate inference on planar graphs using loop calculus and belief progagation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chertkov, Michael; Gomez, Vicenc; Kappen, Hilbert

We introduce novel results for approximate inference on planar graphical models using the loop calculus framework. The loop calculus (Chertkov and Chernyak, 2006b) allows to express the exact partition function Z of a graphical model as a finite sum of terms that can be evaluated once the belief propagation (BP) solution is known. In general, full summation over all correction terms is intractable. We develop an algorithm for the approach presented in Chertkov et al. (2008) which represents an efficient truncation scheme on planar graphs and a new representation of the series in terms of Pfaffians of matrices. We analyzemore » in detail both the loop series and the Pfaffian series for models with binary variables and pairwise interactions, and show that the first term of the Pfaffian series can provide very accurate approximations. The algorithm outperforms previous truncation schemes of the loop series and is competitive with other state-of-the-art methods for approximate inference.« less

Robust Algorithms for on Minor-Free Graphs Based on the Sherali-Adams Hierarchy

NASA Astrophysics Data System (ADS)

Magen, Avner; Moharrami, Mohammad

This work provides a Linear Programming-based Polynomial Time Approximation Scheme (PTAS) for two classical NP-hard problems on graphs when the input graph is guaranteed to be planar, or more generally Minor Free. The algorithm applies a sufficiently large number (some function of when approximation is required) of rounds of the so-called Sherali-Adams Lift-and-Project system. needed to obtain a -approximation, where f is some function that depends only on the graph that should be avoided as a minor. The problem we discuss are the well-studied problems, the and problems. An curious fact we expose is that in the world of minor-free graph, the is harder in some sense than the.

Observing planar cell polarity in multiciliated mouse airway epithelial cells.

PubMed

Vladar, Eszter K; Lee, Yin Loon; Stearns, Tim; Axelrod, Jeffrey D

2015-01-01

The concerted movement of cilia propels inhaled contaminants out of the lungs, safeguarding the respiratory system from toxins, pathogens, pollutants, and allergens. Motile cilia on the multiciliated cells (MCCs) of the airway epithelium are physically oriented along the tissue axis for directional motility, which depends on the planar cell polarity (PCP) signaling pathway. The MCCs of the mouse respiratory epithelium have emerged as an important model for the study of motile ciliogenesis and the PCP signaling mechanism. Unlike other motile ciliated or planar polarized tissues, airway epithelial cells are relatively easily accessible and primary cultures faithfully model many of the essential features of the in vivo tissue. There is growing interest in understanding how cells acquire and polarize motile cilia due to the impact of mucociliary clearance on respiratory health. Here, we present methods for observing and quantifying the planar polarized orientation of motile cilia both in vivo and in primary culture airway epithelial cells. We describe how to acquire and evaluate electron and light microscopy images of ciliary ultrastructural features that reveal planar polarized orientation. Furthermore, we describe the immunofluorescence localization of PCP pathway components as a simple readout for airway epithelial planar polarization and ciliary orientation. These methods can be adapted to observe ciliary orientation in other multi- and monociliated cells and to detect PCP pathway activity in any tissue or cell type. Copyright © 2015 Elsevier Inc. All rights reserved.

Tutte polynomial in functional magnetic resonance imaging

NASA Astrophysics Data System (ADS)

García-Castillón, Marlly V.

2015-09-01

Methods of graph theory are applied to the processing of functional magnetic resonance images. Specifically the Tutte polynomial is used to analyze such kind of images. Functional Magnetic Resonance Imaging provide us connectivity networks in the brain which are represented by graphs and the Tutte polynomial will be applied. The problem of computing the Tutte polynomial for a given graph is #P-hard even for planar graphs. For a practical application the maple packages "GraphTheory" and "SpecialGraphs" will be used. We will consider certain diagram which is depicting functional connectivity, specifically between frontal and posterior areas, in autism during an inferential text comprehension task. The Tutte polynomial for the resulting neural networks will be computed and some numerical invariants for such network will be obtained. Our results show that the Tutte polynomial is a powerful tool to analyze and characterize the networks obtained from functional magnetic resonance imaging.

A tool for filtering information in complex systems

PubMed Central

Tumminello, M.; Aste, T.; Di Matteo, T.; Mantegna, R. N.

2005-01-01

We introduce a technique to filter out complex data sets by extracting a subgraph of representative links. Such a filtering can be tuned up to any desired level by controlling the genus of the resulting graph. We show that this technique is especially suitable for correlation-based graphs, giving filtered graphs that preserve the hierarchical organization of the minimum spanning tree but containing a larger amount of information in their internal structure. In particular in the case of planar filtered graphs (genus equal to 0), triangular loops and four-element cliques are formed. The application of this filtering procedure to 100 stocks in the U.S. equity markets shows that such loops and cliques have important and significant relationships with the market structure and properties. PMID:16027373

A tool for filtering information in complex systems.

PubMed

Tumminello, M; Aste, T; Di Matteo, T; Mantegna, R N

2005-07-26

We introduce a technique to filter out complex data sets by extracting a subgraph of representative links. Such a filtering can be tuned up to any desired level by controlling the genus of the resulting graph. We show that this technique is especially suitable for correlation-based graphs, giving filtered graphs that preserve the hierarchical organization of the minimum spanning tree but containing a larger amount of information in their internal structure. In particular in the case of planar filtered graphs (genus equal to 0), triangular loops and four-element cliques are formed. The application of this filtering procedure to 100 stocks in the U.S. equity markets shows that such loops and cliques have important and significant relationships with the market structure and properties.

Planar Embedding of Planar Graphs,

DTIC Science & Technology

1983-02-01

Stanford University and supported by a Chaim Wcismann postdoctoral fellowship and DARPA contract MDAOO3-C-0102. Current address: Institute of ...rectilinear embeddings (both with and without cross - overs), using the bounding box area cost. He proved that a tree of vertices with maximum degree 4 can...be laid out without crossovers in an area that is linear in the number of edges (or vertices). He also showed how Ato get a such an embedding for any

Solving Hard Computational Problems Efficiently: Asymptotic Parametric Complexity 3-Coloring Algorithm

PubMed Central

Martín H., José Antonio

2013-01-01

Many practical problems in almost all scientific and technological disciplines have been classified as computationally hard (NP-hard or even NP-complete). In life sciences, combinatorial optimization problems frequently arise in molecular biology, e.g., genome sequencing; global alignment of multiple genomes; identifying siblings or discovery of dysregulated pathways. In almost all of these problems, there is the need for proving a hypothesis about certain property of an object that can be present if and only if it adopts some particular admissible structure (an NP-certificate) or be absent (no admissible structure), however, none of the standard approaches can discard the hypothesis when no solution can be found, since none can provide a proof that there is no admissible structure. This article presents an algorithm that introduces a novel type of solution method to “efficiently” solve the graph 3-coloring problem; an NP-complete problem. The proposed method provides certificates (proofs) in both cases: present or absent, so it is possible to accept or reject the hypothesis on the basis of a rigorous proof. It provides exact solutions and is polynomial-time (i.e., efficient) however parametric. The only requirement is sufficient computational power, which is controlled by the parameter . Nevertheless, here it is proved that the probability of requiring a value of to obtain a solution for a random graph decreases exponentially: , making tractable almost all problem instances. Thorough experimental analyses were performed. The algorithm was tested on random graphs, planar graphs and 4-regular planar graphs. The obtained experimental results are in accordance with the theoretical expected results. PMID:23349711

Unimodular lattice triangulations as small-world and scale-free random graphs

NASA Astrophysics Data System (ADS)

Krüger, B.; Schmidt, E. M.; Mecke, K.

2015-02-01

Real-world networks, e.g., the social relations or world-wide-web graphs, exhibit both small-world and scale-free behaviour. We interpret lattice triangulations as planar graphs by identifying triangulation vertices with graph nodes and one-dimensional simplices with edges. Since these triangulations are ergodic with respect to a certain Pachner flip, applying different Monte Carlo simulations enables us to calculate average properties of random triangulations, as well as canonical ensemble averages, using an energy functional that is approximately the variance of the degree distribution. All considered triangulations have clustering coefficients comparable with real-world graphs; for the canonical ensemble there are inverse temperatures with small shortest path length independent of system size. Tuning the inverse temperature to a quasi-critical value leads to an indication of scale-free behaviour for degrees k≥slant 5. Using triangulations as a random graph model can improve the understanding of real-world networks, especially if the actual distance of the embedded nodes becomes important.

Graph-based surface reconstruction from stereo pairs using image segmentation

NASA Astrophysics Data System (ADS)

Bleyer, Michael; Gelautz, Margrit

2005-01-01

This paper describes a novel stereo matching algorithm for epipolar rectified images. The method applies colour segmentation on the reference image. The use of segmentation makes the algorithm capable of handling large untextured regions, estimating precise depth boundaries and propagating disparity information to occluded regions, which are challenging tasks for conventional stereo methods. We model disparity inside a segment by a planar equation. Initial disparity segments are clustered to form a set of disparity layers, which are planar surfaces that are likely to occur in the scene. Assignments of segments to disparity layers are then derived by minimization of a global cost function via a robust optimization technique that employs graph cuts. The cost function is defined on the pixel level, as well as on the segment level. While the pixel level measures the data similarity based on the current disparity map and detects occlusions symmetrically in both views, the segment level propagates the segmentation information and incorporates a smoothness term. New planar models are then generated based on the disparity layers' spatial extents. Results obtained for benchmark and self-recorded image pairs indicate that the proposed method is able to compete with the best-performing state-of-the-art algorithms.

The Effect of a Graph-Oriented Computer-Assisted Project-Based Learning Environment on Argumentation Skills

ERIC Educational Resources Information Center

Hsu, P. -S.; Van Dyke, M.; Chen, Y.; Smith, T. J.

2015-01-01

The purpose of this quasi-experimental study was to explore how seventh graders in a suburban school in the United States developed argumentation skills and science knowledge in a project-based learning environment that incorporated a graph-oriented, computer-assisted application. A total of 54 students (three classes) comprised this treatment…

Building occupancy simulation and data assimilation using a graph-based agent-oriented model

NASA Astrophysics Data System (ADS)

Rai, Sanish; Hu, Xiaolin

2018-07-01

Building occupancy simulation and estimation simulates the dynamics of occupants and estimates their real-time spatial distribution in a building. It requires a simulation model and an algorithm for data assimilation that assimilates real-time sensor data into the simulation model. Existing building occupancy simulation models include agent-based models and graph-based models. The agent-based models suffer high computation cost for simulating large numbers of occupants, and graph-based models overlook the heterogeneity and detailed behaviors of individuals. Recognizing the limitations of existing models, this paper presents a new graph-based agent-oriented model which can efficiently simulate large numbers of occupants in various kinds of building structures. To support real-time occupancy dynamics estimation, a data assimilation framework based on Sequential Monte Carlo Methods is also developed and applied to the graph-based agent-oriented model to assimilate real-time sensor data. Experimental results show the effectiveness of the developed model and the data assimilation framework. The major contributions of this work are to provide an efficient model for building occupancy simulation that can accommodate large numbers of occupants and an effective data assimilation framework that can provide real-time estimations of building occupancy from sensor data.

A Direct Mapping of Max k-SAT and High Order Parity Checks to a Chimera Graph

PubMed Central

Chancellor, N.; Zohren, S.; Warburton, P. A.; Benjamin, S. C.; Roberts, S.

2016-01-01

We demonstrate a direct mapping of max k-SAT problems (and weighted max k-SAT) to a Chimera graph, which is the non-planar hardware graph of the devices built by D-Wave Systems Inc. We further show that this mapping can be used to map a similar class of maximum satisfiability problems where the clauses are replaced by parity checks over potentially large numbers of bits. The latter is of specific interest for applications in decoding for communication. We discuss an example in which the decoding of a turbo code, which has been demonstrated to perform near the Shannon limit, can be mapped to a Chimera graph. The weighted max k-SAT problem is the most general class of satisfiability problems, so our result effectively demonstrates how any satisfiability problem may be directly mapped to a Chimera graph. Our methods faithfully reproduce the low energy spectrum of the target problems, so therefore may also be used for maximum entropy inference. PMID:27857179

Complexity of chemical graphs in terms of size, branching, and cyclicity.

PubMed

Balaban, A T; Mills, D; Kodali, V; Basak, S C

2006-08-01

Chemical graph complexity depends on many factors, but the main ones are size, branching, and cyclicity. Some molecular descriptors embrace together all these three parameters, which cannot then be disentangled. The topological index J (and its refinements that include accounting for bond multiplicity and the presence of heteroatoms) was designed to compensate in a significant measure for graph size and cyclicity, and therefore it contains information mainly on branching. In order to separate these factors, two new indices (F and G) related with J are proposed, which allow to group together graphs with the same size into families of constitutional formulas differing in their branching and cyclicity. A comparison with other topological indices revealed that a few other topological indices vary similarly with index G, notably DN2S4 among the triplet indices, and TOTOP among the indices contained in the Molconn-Z program. This comparison involved all possible chemical graphs (i.e. connected planar graphs with vertex degrees not higher than four) with four through six vertices, and all possible alkanes with four through nine carbon atoms.

Heuristic-driven graph wavelet modeling of complex terrain

NASA Astrophysics Data System (ADS)

Cioacǎ, Teodor; Dumitrescu, Bogdan; Stupariu, Mihai-Sorin; Pǎtru-Stupariu, Ileana; Nǎpǎrus, Magdalena; Stoicescu, Ioana; Peringer, Alexander; Buttler, Alexandre; Golay, François

2015-03-01

We present a novel method for building a multi-resolution representation of large digital surface models. The surface points coincide with the nodes of a planar graph which can be processed using a critically sampled, invertible lifting scheme. To drive the lazy wavelet node partitioning, we employ an attribute aware cost function based on the generalized quadric error metric. The resulting algorithm can be applied to multivariate data by storing additional attributes at the graph's nodes. We discuss how the cost computation mechanism can be coupled with the lifting scheme and examine the results by evaluating the root mean square error. The algorithm is experimentally tested using two multivariate LiDAR sets representing terrain surface and vegetation structure with different sampling densities.

Gain-Sparsity and Symmetry-Forced Rigidity in the Plane.

PubMed

Jordán, Tibor; Kaszanitzky, Viktória E; Tanigawa, Shin-Ichi

We consider planar bar-and-joint frameworks with discrete point group symmetry in which the joint positions are as generic as possible subject to the symmetry constraint. We provide combinatorial characterizations for symmetry-forced rigidity of such structures with rotation symmetry or dihedral symmetry of order 2 k with odd k , unifying and extending previous work on this subject. We also explore the matroidal background of our results and show that the matroids induced by the row independence of the orbit matrices of the symmetric frameworks are isomorphic to gain sparsity matroids defined on the quotient graph of the framework, whose edges are labeled by elements of the corresponding symmetry group. The proofs are based on new Henneberg type inductive constructions of the gain graphs that correspond to the bases of the matroids in question, which can also be seen as symmetry preserving graph operations in the original graph.

Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

DOE PAGES

Shen, Youde; Chen, Renjie; Yu, Xuechao; ...

2016-06-02

Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor–liquid–solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. In this paper, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs–Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed tomore » impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs–Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. Finally, these results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices.« less

Gibbs-Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth.

PubMed

Shen, Youde; Chen, Renjie; Yu, Xuechao; Wang, Qijie; Jungjohann, Katherine L; Dayeh, Shadi A; Wu, Tom

2016-07-13

Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices.

System analysis through bond graph modeling

NASA Astrophysics Data System (ADS)

McBride, Robert Thomas

2005-07-01

Modeling and simulation form an integral role in the engineering design process. An accurate mathematical description of a system provides the design engineer the flexibility to perform trade studies quickly and accurately to expedite the design process. Most often, the mathematical model of the system contains components of different engineering disciplines. A modeling methodology that can handle these types of systems might be used in an indirect fashion to extract added information from the model. This research examines the ability of a modeling methodology to provide added insight into system analysis and design. The modeling methodology used is bond graph modeling. An investigation into the creation of a bond graph model using the Lagrangian of the system is provided. Upon creation of the bond graph, system analysis is performed. To aid in the system analysis, an object-oriented approach to bond graph modeling is introduced. A framework is provided to simulate the bond graph directly. Through object-oriented simulation of a bond graph, the information contained within the bond graph can be exploited to create a measurement of system efficiency. A definition of system efficiency is given. This measurement of efficiency is used in the design of different controllers of varying architectures. Optimal control of a missile autopilot is discussed within the framework of the calculated system efficiency.

Microtubules Enable the Planar Cell Polarity of Airway Cilia

PubMed Central

Vladar, Eszter K.; Bayly, Roy D.; Sangoram, Ashvin; Scott, Matthew P.; Axelrod, Jeffrey D.

2012-01-01

Summary Background Airway cilia must be physically oriented along the longitudinal tissue axis for concerted, directional motility that is essential for proper mucociliary clearance. Results We show that Planar Cell Polarity (PCP) signaling specifies directionality and orients respiratory cilia. Within all airway epithelial cells a conserved set of PCP proteins shows interdependent, asymmetric junctional localization; non-autonomous signaling coordinates polarization between cells; and a polarized microtubule (MT) network is likely required for asymmetric PCP protein localization. We find that basal bodies dock after polarity of PCP proteins is established, are polarized nearly simultaneously, and refinement of basal body/cilium orientation continues during airway epithelial development. Unique to mature multiciliated cells, we identify PCP-regulated, planar polarized MTs that originate from basal bodies and interact, via their plus ends, with membrane domains associated with the PCP proteins Frizzled and Dishevelled. Disruption of MTs leads to misoriented cilia. Conclusions A conserved PCP pathway orients airway cilia by communicating polarity information from asymmetric membrane domains at the apical junctions, through MTs, to orient the MT and actin based network of ciliary basal bodies below the apical surface. PMID:23122850

A simple proof of orientability in colored group field theory.

PubMed

Caravelli, Francesco

2012-01-01

Group field theory is an emerging field at the boundary between Quantum Gravity, Statistical Mechanics and Quantum Field Theory and provides a path integral for the gluing of n-simplices. Colored group field theory has been introduced in order to improve the renormalizability of the theory and associates colors to the faces of the simplices. The theory of crystallizations is instead a field at the boundary between graph theory and combinatorial topology and deals with n-simplices as colored graphs. Several techniques have been introduced in order to study the topology of the pseudo-manifold associated to the colored graph. Although of the similarity between colored group field theory and the theory of crystallizations, the connection between the two fields has never been made explicit. In this short note we use results from the theory of crystallizations to prove that color in group field theories guarantees orientability of the piecewise linear pseudo-manifolds associated to each graph generated perturbatively. Colored group field theories generate orientable pseudo-manifolds. The origin of orientability is the presence of two interaction vertices in the action of colored group field theories. In order to obtain the result, we made the connection between the theory of crystallizations and colored group field theory.

A Cross-Cultural Study of the Effect of a Graph-Oriented Computer-Assisted Project-Based Learning Environment on Middle School Students' Science Knowledge and Argumentation Skills

ERIC Educational Resources Information Center

Hsu, P.-S.; Van Dyke, M.; Chen, Y.; Smith, T. J.

2016-01-01

The purpose of this mixed-methods study was to explore how seventh graders in a suburban school in the United States and sixth graders in an urban school in Taiwan developed argumentation skills and science knowledge in a project-based learning environment that incorporated a graph-oriented, computer-assisted application (GOCAA). A total of 42…

Distance Magic-Type and Distance Antimagic-Type Labelings of Graphs

NASA Astrophysics Data System (ADS)

Freyberg, Bryan J.

Generally speaking, a distance magic-type labeling of a graph G of order n is a bijection l from the vertex set of the graph to the first n natural numbers or to the elements of a group of order n, with the property that the weight of each vertex is the same. The weight of a vertex x is defined as the sum (or appropriate group operation) of all the labels of vertices adjacent to x. If instead we require that all weights differ, then we refer to the labeling as a distance antimagic-type labeling. This idea can be generalized for directed graphs; the weight will take into consideration the direction of the arcs. In this manuscript, we provide new results for d-handicap labeling, a distance antimagic-type labeling, and introduce a new distance magic-type labeling called orientable Gamma-distance magic labeling. A d-handicap distance antimagic labeling (or just d-handicap labeling for short) of a graph G = ( V,E) of order n is a bijection l from V to the set {1,2,...,n} with induced weight function [special characters omitted]. such that l(xi) = i and the sequence of weights w(x 1),w(x2),...,w (xn) forms an arithmetic sequence with constant difference d at least 1. If a graph G admits a d-handicap labeling, we say G is a d-handicap graph. A d-handicap incomplete tournament, H(n,k,d ) is an incomplete tournament of n teams ranked with the first n natural numbers such that each team plays exactly k games and the strength of schedule of the ith ranked team is d more than the i + 1st ranked team. That is, strength of schedule increases arithmetically with strength of team. Constructing an H(n,k,d) is equivalent to finding a d-handicap labeling of a k-regular graph of order n.. In Chapter 2 we provide general constructions for every d for large classes of both n and k, providing breadfth and depth to the catalog of known H(n,k,d)'s. In Chapters 3 - 6, we introduce a new type of labeling called orientable Gamma-distance magic labeling. Let Gamma be an abelian group of order n. If for a graph G = (V,E) of order n there exists an orientation of the edges of G and a companion bijection from V to Gamma with the property that there is an element mu of Gamma (called the magic constant) such that [special characters omitted] where w(x) is the weight of vertex x, we say that G is orientable Gamma -distance magic. In addition to introducing the concept, we provide numerous results on orientable Zn-distance magic graphs, where Zn is the cyclic group of order n.. In Chapter 7, we summarize the results of this dissertation and provide suggestions for future work.

Object-oriented requirements analysis: A quick tour

NASA Technical Reports Server (NTRS)

Berard, Edward V.

1990-01-01

Of all the approaches to software development, an object-oriented approach appears to be both the most beneficial and the most popular. The description of the object-oriented approach is presented in the form of the view graphs.

Loops in hierarchical channel networks

NASA Astrophysics Data System (ADS)

Katifori, Eleni; Magnasco, Marcelo

2012-02-01

Nature provides us with many examples of planar distribution and structural networks having dense sets of closed loops. An archetype of this form of network organization is the vasculature of dicotyledonous leaves, which showcases a hierarchically-nested architecture. Although a number of methods have been proposed to measure aspects of the structure of such networks, a robust metric to quantify their hierarchical organization is still lacking. We present an algorithmic framework that allows mapping loopy networks to binary trees, preserving in the connectivity of the trees the architecture of the original graph. We apply this framework to investigate computer generated and natural graphs extracted from digitized images of dicotyledonous leaves and animal vasculature. We calculate various metrics on the corresponding trees and discuss the relationship of these quantities to the architectural organization of the original graphs. This algorithmic framework decouples the geometric information from the metric topology (connectivity and edge weight) and it ultimately allows us to perform a quantitative statistical comparison between predictions of theoretical models and naturally occurring loopy graphs.

MorphoGraphX: A platform for quantifying morphogenesis in 4D.

PubMed

Barbier de Reuille, Pierre; Routier-Kierzkowska, Anne-Lise; Kierzkowski, Daniel; Bassel, George W; Schüpbach, Thierry; Tauriello, Gerardo; Bajpai, Namrata; Strauss, Sören; Weber, Alain; Kiss, Annamaria; Burian, Agata; Hofhuis, Hugo; Sapala, Aleksandra; Lipowczan, Marcin; Heimlicher, Maria B; Robinson, Sarah; Bayer, Emmanuelle M; Basler, Konrad; Koumoutsakos, Petros; Roeder, Adrienne H K; Aegerter-Wilmsen, Tinri; Nakayama, Naomi; Tsiantis, Miltos; Hay, Angela; Kwiatkowska, Dorota; Xenarios, Ioannis; Kuhlemeier, Cris; Smith, Richard S

2015-05-06

Morphogenesis emerges from complex multiscale interactions between genetic and mechanical processes. To understand these processes, the evolution of cell shape, proliferation and gene expression must be quantified. This quantification is usually performed either in full 3D, which is computationally expensive and technically challenging, or on 2D planar projections, which introduces geometrical artifacts on highly curved organs. Here we present MorphoGraphX ( www.MorphoGraphX.org), a software that bridges this gap by working directly with curved surface images extracted from 3D data. In addition to traditional 3D image analysis, we have developed algorithms to operate on curved surfaces, such as cell segmentation, lineage tracking and fluorescence signal quantification. The software's modular design makes it easy to include existing libraries, or to implement new algorithms. Cell geometries extracted with MorphoGraphX can be exported and used as templates for simulation models, providing a powerful platform to investigate the interactions between shape, genes and growth.

From free fields to AdS space. II

NASA Astrophysics Data System (ADS)

Gopakumar, Rajesh

2004-07-01

We continue with the program of paper I [Phys. Rev. D 70, 025009 (2004)] to implement open-closed string duality on free gauge field theory (in the large-N limit). In this paper we consider correlators such as <∏ni=1TrΦJi(xi)>. The Schwinger parametrization of this n-point function exhibits a partial gluing up into a set of basic skeleton graphs. We argue that the moduli space of the planar skeleton graphs is exactly the same as the moduli space of genus zero Riemann surfaces with n holes. In other words, we can explicitly rewrite the n-point (planar) free-field correlator as an integral over the moduli space of a sphere with n holes. A preliminary study of the integrand also indicates compatibility with a string theory on AdS space. The details of our argument are quite insensitive to the specific form of the operators and generalize to diagrams of a higher genus as well. We take this as evidence of the field theory’s ability to reorganize itself into a string theory.

Method for directional hydraulic fracturing

DOEpatents

Swanson, David E.; Daly, Daniel W.

1994-01-01

A method for directional hydraulic fracturing using borehole seals to confine pressurized fluid in planar permeable regions, comprising: placing a sealant in the hole of a structure selected from geologic or cemented formations to fill the space between a permeable planar component and the geologic or cemented formation in the vicinity of the permeable planar component; making a hydraulic connection between the permeable planar component and a pump; permitting the sealant to cure and thereby provide both mechanical and hydraulic confinement to the permeable planar component; and pumping a fluid from the pump into the permeable planar component to internally pressurize the permeable planar component to initiate a fracture in the formation, the fracture being disposed in the same orientation as the permeable planar component.

Oriented matroids—combinatorial structures underlying loop quantum gravity

NASA Astrophysics Data System (ADS)

Brunnemann, Johannes; Rideout, David

2010-10-01

We analyze combinatorial structures which play a central role in determining spectral properties of the volume operator (Ashtekar A and Lewandowski J 1998 Adv. Theor. Math. Phys. 1 388) in loop quantum gravity (LQG). These structures encode geometrical information of the embedding of arbitrary valence vertices of a graph in three-dimensional Riemannian space and can be represented by sign strings containing relative orientations of embedded edges. We demonstrate that these signature factors are a special representation of the general mathematical concept of an oriented matroid (Ziegler G M 1998 Electron. J. Comb.; Björner A et al 1999 Oriented Matroids (Cambridge: Cambridge University Press)). Moreover, we show that oriented matroids can also be used to describe the topology (connectedness) of directed graphs. Hence, the mathematical methods developed for oriented matroids can be applied to the difficult combinatorics of embedded graphs underlying the construction of LQG. As a first application we revisit the analysis of Brunnemann and Rideout (2008 Class. Quantum Grav. 25 065001 and 065002), and find that enumeration of all possible sign configurations used there is equivalent to enumerating all realizable oriented matroids of rank 3 (Ziegler G M 1998 Electron. J. Comb.; Björner A et al 1999 Oriented Matroids (Cambridge: Cambridge University Press)), and thus can be greatly simplified. We find that for 7-valent vertices having no coplanar triples of edge tangents, the smallest non-zero eigenvalue of the volume spectrum does not grow as one increases the maximum spin jmax at the vertex, for any orientation of the edge tangents. This indicates that, in contrast to the area operator, considering large jmax does not necessarily imply large volume eigenvalues. In addition we give an outlook to possible starting points for rewriting the combinatorics of LQG in terms of oriented matroids.

Crystallographic Orientation Identification in Multicrystalline Silicon Wafers Using NIR Transmission Intensity

NASA Astrophysics Data System (ADS)

Skenes, Kevin; Kumar, Arkadeep; Prasath, R. G. R.; Danyluk, Steven

2018-02-01

Near-infrared (NIR) polariscopy is a technique used for the non-destructive evaluation of the in-plane stresses in photovoltaic silicon wafers. Accurate evaluation of these stresses requires correct identification of the stress-optic coefficient, a material property which relates photoelastic parameters to physical stresses. The material stress-optic coefficient of silicon varies with crystallographic orientation. This variation poses a unique problem when measuring stresses in multicrystalline silicon (mc-Si) wafers. This paper concludes that the crystallographic orientation of silicon can be estimated by measuring the transmission of NIR light through the material. The transmission of NIR light through monocrystalline wafers of known orientation were compared with the transmission of NIR light through various grains in mc-Si wafers. X-ray diffraction was then used to verify the relationship by obtaining the crystallographic orientations of these assorted mc-Si grains. Variation of transmission intensity for different crystallographic orientations is further explained by using planar atomic density. The relationship between transmission intensity and planar atomic density appears to be linear.

Theoretical investigation of confocal microscopy using an elliptically polarized cylindrical vector laser beam: Visualization of quantum emitters near interfaces

NASA Astrophysics Data System (ADS)

Boichenko, Stepan

2018-04-01

We theoretically study laser-scanning confocal fluorescence microscopy using elliptically polarized cylindrical vector excitation light as a tool for visualization of arbitrarily oriented single quantum dipole emitters located (1) near planar surfaces enhancing fluorescence, (2) in a thin supported polymer film, (3) in a freestanding polymer film, and (4) in a dielectric planar microcavity. It is shown analytically that by using a tightly focused azimuthally polarized beam, it is possible to exclude completely the orientational dependence of the image intensity maximum of a quantum emitter that absorbs light as a pair of incoherent independent linear dipoles. For linear dipole quantum emitters, the orientational independence degree higher than 0.9 can normally be achieved (this quantity equal to 1 corresponds to completely excluded orientational dependence) if the collection efficiency of the microscope objective and the emitter's total quantum yield are not strongly orientationally dependent. Thus, the visualization of arbitrarily oriented single quantum emitters by means of the studied technique can be performed quite efficiently.

MorphoGraphX: A platform for quantifying morphogenesis in 4D

PubMed Central

Barbier de Reuille, Pierre; Routier-Kierzkowska, Anne-Lise; Kierzkowski, Daniel; Bassel, George W; Schüpbach, Thierry; Tauriello, Gerardo; Bajpai, Namrata; Strauss, Sören; Weber, Alain; Kiss, Annamaria; Burian, Agata; Hofhuis, Hugo; Sapala, Aleksandra; Lipowczan, Marcin; Heimlicher, Maria B; Robinson, Sarah; Bayer, Emmanuelle M; Basler, Konrad; Koumoutsakos, Petros; Roeder, Adrienne HK; Aegerter-Wilmsen, Tinri; Nakayama, Naomi; Tsiantis, Miltos; Hay, Angela; Kwiatkowska, Dorota; Xenarios, Ioannis; Kuhlemeier, Cris; Smith, Richard S

2015-01-01

Morphogenesis emerges from complex multiscale interactions between genetic and mechanical processes. To understand these processes, the evolution of cell shape, proliferation and gene expression must be quantified. This quantification is usually performed either in full 3D, which is computationally expensive and technically challenging, or on 2D planar projections, which introduces geometrical artifacts on highly curved organs. Here we present MorphoGraphX (www.MorphoGraphX.org), a software that bridges this gap by working directly with curved surface images extracted from 3D data. In addition to traditional 3D image analysis, we have developed algorithms to operate on curved surfaces, such as cell segmentation, lineage tracking and fluorescence signal quantification. The software's modular design makes it easy to include existing libraries, or to implement new algorithms. Cell geometries extracted with MorphoGraphX can be exported and used as templates for simulation models, providing a powerful platform to investigate the interactions between shape, genes and growth. DOI: http://dx.doi.org/10.7554/eLife.05864.001 PMID:25946108

A sampling strategy to estimate the area and perimeter of irregularly shaped planar regions

Treesearch

Timothy G. Gregoire; Harry T. Valentine

1995-01-01

The length of a randomly oriented ray emanating from an interior point of a planar region can be used to unbiasedly estimate the region's area and perimeter. Estimators and corresponding variance estimators under various selection strategies are presented.

Modeling of viscous damping of perforated planar microstructures. Applications in acoustics

NASA Astrophysics Data System (ADS)

Homentcovschi, Dorel; Miles, Ronald N.

2004-11-01

The paper contains an analysis of the viscous damping in perforated planar microstructures that often serve as backplates or protecting surfaces in capacitive microsensors. The focus of this work is on planar surfaces containing an offset system of periodic oval holes or its limit cases: a system of circular holes or of slits. The viscous damping is calculated as the sum of squeeze film and the holes' resistances. The optimum number of holes is determined which minimizes the total viscous damping for a given percentage of open area. Graphs and formulas are provided for designing these devices. In the case the open area is higher than 15% the numerical results show that the influence of the holes' geometry (circular or oval) has a slight influence on viscous damping. As the planar structures containing oval holes assure a better protection against dust particles and water drops, they should be preferred in designing protective surfaces for microphones working in a natural environment. The obtained results also can be applied in designing other MEMS devices that use capacitive sensing such as accelerometers, micromechanical switches, resonators, and tunable microoptical interferometers. .

Stock market network’s topological stability: Evidence from planar maximally filtered graph and minimal spanning tree

NASA Astrophysics Data System (ADS)

Yan, Xin-Guo; Xie, Chi; Wang, Gang-Jin

2015-08-01

We study the topological stability of stock market network by investigating the topological robustness, namely the ability of the network to resist structural or topological changes. The stock market network is extracted by minimal spanning tree (MST) and planar maximally filtered graph (PMFG). We find that the specific delisting thresholds of the listed companies exist in both MST and PMFG networks. In comparison with MST, PMFG provides more information and is better for the aim of exploring stock market network’s robustness. The PMFG before the US sub-prime crisis (i.e., from June 2005 to May 2007) has a stronger robustness against the intentional topological damage than the other two sub-periods (i.e., from June 2007 to May 2009 and from June 2009 to May 2011). We also find that the nonfractal property exists in MSTs of S&P 500, i.e., the highly connected nodes link with each other directly, which indicates that the MSTs are vulnerable to the removal of such important nodes. Moreover, the financial institutions and high technology companies are important in maintaining the stability of S&P 500 network.

High microwave attenuation performance of planar carbonyl iron particles with orientation of shape anisotropy field

NASA Astrophysics Data System (ADS)

Guo, Cheng; Yang, Zhihong; Shen, Shile; Liang, Juan; Xu, Guoyue

2018-05-01

Planar anisotropy carbonyl iron (PACI) particles were prepared from commercial spherical carbonyl iron particles through a high performance ball-milling technique. The paraffin composites with orientation of shape anisotropy field for these PACI particles were obtained by applying an external magnetic field during the fabrication process. The frequency-dependent complex permeability values of these prepared paraffin composites have been investigated in the frequency range of 1-18 GHz. The results demonstrate that the orientation of shape anisotropy field for these PACI particles can effectively increase the complex permeability and decrease the complex permittivity values. Benefit from the enhancement in the complex permeability and reduction in the complex permittivity, the better impedance matching condition can be obtained and thus the good microwave absorption performance can be achieved for the samples with enough magnetic field orientation time.

The Visual Representation of 3D Object Orientation in Parietal Cortex

PubMed Central

Cowan, Noah J.; Angelaki, Dora E.

2013-01-01

An accurate representation of three-dimensional (3D) object orientation is essential for interacting with the environment. Where and how the brain visually encodes 3D object orientation remains unknown, but prior studies suggest the caudal intraparietal area (CIP) may be involved. Here, we develop rigorous analytical methods for quantifying 3D orientation tuning curves, and use these tools to the study the neural coding of surface orientation. Specifically, we show that single neurons in area CIP of the rhesus macaque jointly encode the slant and tilt of a planar surface, and that across the population, the distribution of preferred slant-tilts is not statistically different from uniform. This suggests that all slant-tilt combinations are equally represented in area CIP. Furthermore, some CIP neurons are found to also represent the third rotational degree of freedom that determines the orientation of the image pattern on the planar surface. Together, the present results suggest that CIP is a critical neural locus for the encoding of all three rotational degrees of freedom specifying an object's 3D spatial orientation. PMID:24305830

Small covers of graph-associahedra and realization of cycles

NASA Astrophysics Data System (ADS)

Gaifullin, A. A.

2016-11-01

An oriented connected closed manifold M^n is called a URC-manifold if for any oriented connected closed manifold N^n of the same dimension there exists a nonzero-degree mapping of a finite-fold covering \\widehat{M}^n of M^n onto N^n. This condition is equivalent to the following: for any n-dimensional integral homology class of any topological space X, a multiple of it can be realized as the image of the fundamental class of a finite-fold covering \\widehat{M}^n of M^n under a continuous mapping f\\colon \\widehat{M}^n\\to X. In 2007 the author gave a constructive proof of Thom's classical result that a multiple of any integral homology class can be realized as an image of the fundamental class of an oriented smooth manifold. This construction yields the existence of URC-manifolds of all dimensions. For an important class of manifolds, the so-called small covers of graph-associahedra corresponding to connected graphs, we prove that either they or their two-fold orientation coverings are URC-manifolds. In particular, we obtain that the two-fold covering of the small cover of the usual Stasheff associahedron is a URC-manifold. In dimensions 4 and higher, this manifold is simpler than all the previously known URC-manifolds. Bibliography: 39 titles.

Effect of planar cuts' orientation on the perceived surface layout and object's shape.

PubMed

Bocheva, Nadejda

2009-07-01

The effect of the orientation of the cutting planes producing planar curves over the surface of an object on its perceived pose and shape was investigated for line drawings representing three-dimensional objects. The results suggest that the orientational flow produced by the surface curves introduces an apparent object rotation in depth and in the image plane and changes in its perceived elongation. The apparent location of the nearest points is determined by the points of maximal view-dependent unsigned curvature of the surface curves. The data are discussed in relation to the interaction of the shape-from-silhouette system and shape-from-contour system and its effect on the interpretation of the surface contours with respect to the surface geometry.

Quantifying loopy network architectures.

PubMed

Katifori, Eleni; Magnasco, Marcelo O

2012-01-01

Biology presents many examples of planar distribution and structural networks having dense sets of closed loops. An archetype of this form of network organization is the vasculature of dicotyledonous leaves, which showcases a hierarchically-nested architecture containing closed loops at many different levels. Although a number of approaches have been proposed to measure aspects of the structure of such networks, a robust metric to quantify their hierarchical organization is still lacking. We present an algorithmic framework, the hierarchical loop decomposition, that allows mapping loopy networks to binary trees, preserving in the connectivity of the trees the architecture of the original graph. We apply this framework to investigate computer generated graphs, such as artificial models and optimal distribution networks, as well as natural graphs extracted from digitized images of dicotyledonous leaves and vasculature of rat cerebral neocortex. We calculate various metrics based on the asymmetry, the cumulative size distribution and the Strahler bifurcation ratios of the corresponding trees and discuss the relationship of these quantities to the architectural organization of the original graphs. This algorithmic framework decouples the geometric information (exact location of edges and nodes) from the metric topology (connectivity and edge weight) and it ultimately allows us to perform a quantitative statistical comparison between predictions of theoretical models and naturally occurring loopy graphs.

Three sets of crystallographic sub-planar structures in quartz formed by tectonic deformation

NASA Astrophysics Data System (ADS)

Derez, Tine; Pennock, Gill; Drury, Martyn; Sintubin, Manuel

2016-05-01

In quartz, multiple sets of fine planar deformation microstructures that have specific crystallographic orientations parallel to planes with low Miller-Bravais indices are commonly considered as shock-induced planar deformation features (PDFs) diagnostic of shock metamorphism. Using polarized light microscopy, we demonstrate that up to three sets of tectonically induced sub-planar fine extinction bands (FEBs), sub-parallel to the basal, γ, ω, and π crystallographic planes, are common in vein quartz in low-grade tectonometamorphic settings. We conclude that the observation of multiple (2-3) sets of fine scale, closely spaced, crystallographically controlled, sub-planar microstructures is not sufficient to unambiguously distinguish PDFs from tectonic FEBs.

Multiscale Embedded Gene Co-expression Network Analysis

PubMed Central

Song, Won-Min; Zhang, Bin

2015-01-01

Gene co-expression network analysis has been shown effective in identifying functional co-expressed gene modules associated with complex human diseases. However, existing techniques to construct co-expression networks require some critical prior information such as predefined number of clusters, numerical thresholds for defining co-expression/interaction, or do not naturally reproduce the hallmarks of complex systems such as the scale-free degree distribution of small-worldness. Previously, a graph filtering technique called Planar Maximally Filtered Graph (PMFG) has been applied to many real-world data sets such as financial stock prices and gene expression to extract meaningful and relevant interactions. However, PMFG is not suitable for large-scale genomic data due to several drawbacks, such as the high computation complexity O(|V|3), the presence of false-positives due to the maximal planarity constraint, and the inadequacy of the clustering framework. Here, we developed a new co-expression network analysis framework called Multiscale Embedded Gene Co-expression Network Analysis (MEGENA) by: i) introducing quality control of co-expression similarities, ii) parallelizing embedded network construction, and iii) developing a novel clustering technique to identify multi-scale clustering structures in Planar Filtered Networks (PFNs). We applied MEGENA to a series of simulated data and the gene expression data in breast carcinoma and lung adenocarcinoma from The Cancer Genome Atlas (TCGA). MEGENA showed improved performance over well-established clustering methods and co-expression network construction approaches. MEGENA revealed not only meaningful multi-scale organizations of co-expressed gene clusters but also novel targets in breast carcinoma and lung adenocarcinoma. PMID:26618778

Multiscale Embedded Gene Co-expression Network Analysis.

PubMed

Song, Won-Min; Zhang, Bin

2015-11-01

Gene co-expression network analysis has been shown effective in identifying functional co-expressed gene modules associated with complex human diseases. However, existing techniques to construct co-expression networks require some critical prior information such as predefined number of clusters, numerical thresholds for defining co-expression/interaction, or do not naturally reproduce the hallmarks of complex systems such as the scale-free degree distribution of small-worldness. Previously, a graph filtering technique called Planar Maximally Filtered Graph (PMFG) has been applied to many real-world data sets such as financial stock prices and gene expression to extract meaningful and relevant interactions. However, PMFG is not suitable for large-scale genomic data due to several drawbacks, such as the high computation complexity O(|V|3), the presence of false-positives due to the maximal planarity constraint, and the inadequacy of the clustering framework. Here, we developed a new co-expression network analysis framework called Multiscale Embedded Gene Co-expression Network Analysis (MEGENA) by: i) introducing quality control of co-expression similarities, ii) parallelizing embedded network construction, and iii) developing a novel clustering technique to identify multi-scale clustering structures in Planar Filtered Networks (PFNs). We applied MEGENA to a series of simulated data and the gene expression data in breast carcinoma and lung adenocarcinoma from The Cancer Genome Atlas (TCGA). MEGENA showed improved performance over well-established clustering methods and co-expression network construction approaches. MEGENA revealed not only meaningful multi-scale organizations of co-expressed gene clusters but also novel targets in breast carcinoma and lung adenocarcinoma.

Electrolytic Cell For Production Of Aluminum Employing Planar Anodes.

DOEpatents

Barnett, Robert J.; Mezner, Michael B.; Bradford, Donald R

2004-10-05

A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising providing a molten salt electrolyte having alumina dissolved therein in an electrolytic cell. A plurality of anodes and cathodes having planar surfaces are disposed in a generally vertical orientation in the electrolyte, the anodes and cathodes arranged in alternating or interleaving relationship to provide anode planar surfaces disposed opposite cathode planar surfaces, the anode comprised of carbon. Electric current is passed through anodes and through the electrolyte to the cathodes depositing aluminum at the cathodes and forming carbon containing gas at the anodes.

Daple coordinates organ-wide and cell-intrinsic polarity to pattern inner-ear hair bundles

PubMed Central

Siletti, Kimberly; Hudspeth, A. J.

2017-01-01

The establishment of planar polarization by mammalian cells necessitates the integration of diverse signaling pathways. In the inner ear, at least two systems regulate the planar polarity of sensory hair bundles. The core planar cell polarity (PCP) proteins coordinate the orientations of hair cells across the epithelial plane. The cell-intrinsic patterning of hair bundles is implemented independently by the G protein complex classically known for orienting the mitotic spindle. Although the primary cilium also participates in each of these pathways, its role and the integration of the two systems are poorly understood. We show that Dishevelled-associating protein with a high frequency of leucine residues (Daple) interacts with PCP and cell-intrinsic signals. Regulated by the cell-intrinsic pathway, Daple is required to maintain the polarized distribution of the core PCP protein Dishevelled and to position the primary cilium at the abneural edge of the apical surface. Our results suggest that the primary cilium or an associated structure influences the domain of cell-intrinsic signals that shape the hair bundle. Daple is therefore essential to orient and pattern sensory hair bundles. PMID:29229865

Mathematical modeling and simulation of the space shuttle imaging radar antennas

NASA Technical Reports Server (NTRS)

Campbell, R. W.; Melick, K. E.; Coffey, E. L., III

1978-01-01

Simulations of space shuttle synthetic aperture radar antennas under the influence of space environmental conditions were carried out at L, C, and X-band. Mathematical difficulties in modeling large, non-planar array antennas are discussed, and an approximate modeling technique is presented. Results for several antenna error conditions are illustrated in far-field profile patterns, earth surface footprint contours, and summary graphs.

Observation of ‘hidden’ planar defects in boron carbide nanowires and identification of their orientations

PubMed Central

2014-01-01

The physical properties of nanostructures strongly depend on their structures, and planar defects in particular could significantly affect the behavior of the nanowires. In this work, planar defects (twins or stacking faults) in boron carbide nanowires are extensively studied by transmission electron microscopy (TEM). Results show that these defects can easily be invisible, i.e., no presence of characteristic defect features like modulated contrast in high-resolution TEM images and streaks in diffraction patterns. The simplified reason of this invisibility is that the viewing direction during TEM examination is not parallel to the (001)-type planar defects. Due to the unique rhombohedral structure of boron carbide, planar defects are only distinctive when the viewing direction is along the axial or short diagonal directions ([100], [010], or 1¯10) within the (001) plane (in-zone condition). However, in most cases, these three characteristic directions are not parallel to the viewing direction when boron carbide nanowires are randomly dispersed on TEM grids. To identify fault orientations (transverse faults or axial faults) of those nanowires whose planar defects are not revealed by TEM, a new approach is developed based on the geometrical analysis between the projected preferred growth direction of a nanowire and specific diffraction spots from diffraction patterns recorded along the axial or short diagonal directions out of the (001) plane (off-zone condition). The approach greatly alleviates tedious TEM examination of the nanowire and helps to establish the reliable structure–property relations. Our study calls attention to researchers to be extremely careful when studying nanowires with potential planar defects by TEM. Understanding the true nature of planar defects is essential in tuning the properties of these nanostructures through manipulating their structures. PMID:24423258

Observation of 'hidden' planar defects in boron carbide nanowires and identification of their orientations.

PubMed

Guan, Zhe; Cao, Baobao; Yang, Yang; Jiang, Youfei; Li, Deyu; Xu, Terry T

2014-01-15

The physical properties of nanostructures strongly depend on their structures, and planar defects in particular could significantly affect the behavior of the nanowires. In this work, planar defects (twins or stacking faults) in boron carbide nanowires are extensively studied by transmission electron microscopy (TEM). Results show that these defects can easily be invisible, i.e., no presence of characteristic defect features like modulated contrast in high-resolution TEM images and streaks in diffraction patterns. The simplified reason of this invisibility is that the viewing direction during TEM examination is not parallel to the (001)-type planar defects. Due to the unique rhombohedral structure of boron carbide, planar defects are only distinctive when the viewing direction is along the axial or short diagonal directions ([100], [010], or 1¯10) within the (001) plane (in-zone condition). However, in most cases, these three characteristic directions are not parallel to the viewing direction when boron carbide nanowires are randomly dispersed on TEM grids. To identify fault orientations (transverse faults or axial faults) of those nanowires whose planar defects are not revealed by TEM, a new approach is developed based on the geometrical analysis between the projected preferred growth direction of a nanowire and specific diffraction spots from diffraction patterns recorded along the axial or short diagonal directions out of the (001) plane (off-zone condition). The approach greatly alleviates tedious TEM examination of the nanowire and helps to establish the reliable structure-property relations. Our study calls attention to researchers to be extremely careful when studying nanowires with potential planar defects by TEM. Understanding the true nature of planar defects is essential in tuning the properties of these nanostructures through manipulating their structures.

Dishevelled links basal body docking and orientation in ciliated epithelial cells

PubMed Central

Vladar, Eszter K.; Axelrod, Jeffrey D.

2014-01-01

Some epithelia contain cells with multiple, motile cilia that beat in a concerted fashion. New tools and experimental systems have facilitated molecular studies of cilium biogenesis and of the coordinated planar polarization of cilia that leads to their concerted motility. Recent, elegant work by Park and colleagues, using embryonic frog epidermis, demonstrates that Dishevelled (Dvl), a key regulator of both the Wnt/β-catenin and Planar Cell Polarity (PCP) pathways, controls both the docking and planar polarization of ciliary basal bodies. PMID:18819800

Augmenting computer networks

NASA Technical Reports Server (NTRS)

Bokhari, S. H.; Raza, A. D.

1984-01-01

Three methods of augmenting computer networks by adding at most one link per processor are discussed: (1) A tree of N nodes may be augmented such that the resulting graph has diameter no greater than 4log sub 2((N+2)/3)-2. Thi O(N(3)) algorithm can be applied to any spanning tree of a connected graph to reduce the diameter of that graph to O(log N); (2) Given a binary tree T and a chain C of N nodes each, C may be augmented to produce C so that T is a subgraph of C. This algorithm is O(N) and may be used to produce augmented chains or rings that have diameter no greater than 2log sub 2((N+2)/3) and are planar; (3) Any rectangular two-dimensional 4 (8) nearest neighbor array of size N = 2(k) may be augmented so that it can emulate a single step shuffle-exchange network of size N/2 in 3(t) time steps.

Topology synthesis of planar ground structures for energy harvesting applications

NASA Astrophysics Data System (ADS)

Danzi, Francesco; Gibert, James; Cestino, Enrico; Frulla, Giacomo

2017-04-01

In this manuscript, we investigate the use topology optimization to design planar resonators with modal fre- quencies that occur at 1 : n ratios for kinetic energy scavenging of ambient vibrations that exhibit at least two frequency components. Furthermore, we are interested in excitations with a fundamental component containing large amounts of energy and secondary component with smaller energy content. This phenomenon is often seen in rotary machines; their frequency spectrum exhibits peaks on multiple harmonics, where the energy is primarily contained in the rotation frequency of the device. Several theoretical resonators are known to exhibit modal frequencies that at integer multiples 1:2 or 1:3. However, designing manufacturable resonators for other geometries is still a daunting task. With this goal in mind, we utilize topology optimization to determine the layout of the resonator. We formulate the problem in its non-dimensional form, eliminating the constraint on the allowable frequency. The frequency can be obtained a posteriori by means of linear scaling. Conversely, to previous research, which use the clamped beam as initial guess, we synthesize the final shape starting from a ground structure (or structural universe) and remove of the unnecessary beams from the initial guess by means of a graph-based filtering scheme. The algorithm determines the simplest structure that gives the desired frequency's ratio. Within the optimization, the structural design is accomplished by a linear FE analysis. The optimization reveals several trends, the most notable being that having members connected orthogonally as in the L-shaped resonator is not the preferred topology of this devices. In order to fully explore the angle of orientation of connected members on the modal characteristics of the device; we derive a reduced-order model that allows a bifurcation analysis on the effect of member orientation on modal frequency. Furthermore, the reduced order approximation is used solve the coupled electro-mechanical equation of a vibration based energy harvester (VEH). Finally, we present the performance of the VEH under various base excitations. These results show an infinite number of topologies that can have integer ratio modal frequencies, and in some cases harvest more power than a nominal L shaped harvester, operating in the linear regime.

Interactive object modelling based on piecewise planar surface patches.

PubMed

Prankl, Johann; Zillich, Michael; Vincze, Markus

2013-06-01

Detecting elements such as planes in 3D is essential to describe objects for applications such as robotics and augmented reality. While plane estimation is well studied, table-top scenes exhibit a large number of planes and methods often lock onto a dominant plane or do not estimate 3D object structure but only homographies of individual planes. In this paper we introduce MDL to the problem of incrementally detecting multiple planar patches in a scene using tracked interest points in image sequences. Planar patches are reconstructed and stored in a keyframe-based graph structure. In case different motions occur, separate object hypotheses are modelled from currently visible patches and patches seen in previous frames. We evaluate our approach on a standard data set published by the Visual Geometry Group at the University of Oxford [24] and on our own data set containing table-top scenes. Results indicate that our approach significantly improves over the state-of-the-art algorithms.

Interactive object modelling based on piecewise planar surface patches☆

PubMed Central

Prankl, Johann; Zillich, Michael; Vincze, Markus

2013-01-01

Detecting elements such as planes in 3D is essential to describe objects for applications such as robotics and augmented reality. While plane estimation is well studied, table-top scenes exhibit a large number of planes and methods often lock onto a dominant plane or do not estimate 3D object structure but only homographies of individual planes. In this paper we introduce MDL to the problem of incrementally detecting multiple planar patches in a scene using tracked interest points in image sequences. Planar patches are reconstructed and stored in a keyframe-based graph structure. In case different motions occur, separate object hypotheses are modelled from currently visible patches and patches seen in previous frames. We evaluate our approach on a standard data set published by the Visual Geometry Group at the University of Oxford [24] and on our own data set containing table-top scenes. Results indicate that our approach significantly improves over the state-of-the-art algorithms. PMID:24511219

Graph characterization via Ihara coefficients.

PubMed

Ren, Peng; Wilson, Richard C; Hancock, Edwin R

2011-02-01

The novel contributions of this paper are twofold. First, we demonstrate how to characterize unweighted graphs in a permutation-invariant manner using the polynomial coefficients from the Ihara zeta function, i.e., the Ihara coefficients. Second, we generalize the definition of the Ihara coefficients to edge-weighted graphs. For an unweighted graph, the Ihara zeta function is the reciprocal of a quasi characteristic polynomial of the adjacency matrix of the associated oriented line graph. Since the Ihara zeta function has poles that give rise to infinities, the most convenient numerically stable representation is to work with the coefficients of the quasi characteristic polynomial. Moreover, the polynomial coefficients are invariant to vertex order permutations and also convey information concerning the cycle structure of the graph. To generalize the representation to edge-weighted graphs, we make use of the reduced Bartholdi zeta function. We prove that the computation of the Ihara coefficients for unweighted graphs is a special case of our proposed method for unit edge weights. We also present a spectral analysis of the Ihara coefficients and indicate their advantages over other graph spectral methods. We apply the proposed graph characterization method to capturing graph-class structure and clustering graphs. Experimental results reveal that the Ihara coefficients are more effective than methods based on Laplacian spectra.

Modulating Thin Film Transistor Characteristics by Texturing the Gate Metal.

PubMed

Nair, Aswathi; Bhattacharya, Prasenjit; Sambandan, Sanjiv

2017-12-20

The development of reliable, high performance integrated circuits based on thin film transistors (TFTs) is of interest for the development of flexible electronic circuits. In this work we illustrate the modulation of TFT transconductance via the texturing of the gate metal created by the addition of a conductive pattern on top of a planar gate. Texturing results in the semiconductor-insulator interface acquiring a non-planar geometry with local variations in the radius of curvature. This influences various TFT parameters such as the subthreshold slope, gate voltage at the onset of conduction, contact resistance and gate capacitance. Specific studies are performed on textures based on periodic striations oriented along different directions. Textured TFTs showed upto ±40% variation in transconductance depending on the texture orientation as compared to conventional planar gate TFTs. Analytical models are developed and compared with experiments. Gain boosting in common source amplifiers based on textured TFTs as compared to conventional TFTs is demonstrated.

Planar Poincare chart - A planar graphic representation of the state of light polarization

NASA Technical Reports Server (NTRS)

Tedjojuwono, Ken K.; Hunter, William W., Jr.; Ocheltree, Stewart L.

1989-01-01

The planar Poincare chart, which represents the complete planar equivalence of the Poincare sphere, is proposed. The four sets of basic lines are drawn on two separate charts for the generalization and convenience of reading the scale. The chart indicates the rotation of the principal axes of linear birefringent material. The relationships between parameters of the two charts are given as 2xi-2phi (orientation angle of the major axis-ellipticity angle) pair and 2alpha-delta (angle of amplitude ratio-phase difference angle) pair. The results are useful for designing and analyzing polarization properties of optical components with birefringent properties.

Biologically Complex Planar Cell Plasma Membranes Supported on Polyelectrolyte Cushions Enhance Transmembrane Protein Mobility and Retain Native Orientation.

PubMed

Liu, Han-Yuan; Chen, Wei-Liang; Ober, Christopher K; Daniel, Susan

2018-01-23

Reconstituted supported lipid bilayers (SLB) are widely used as in vitro cell-surface models because they are compatible with a variety of surface-based analytical techniques. However, one of the challenges of using SLBs as a model of the cell surface is the limited complexity in membrane composition, including the incorporation of transmembrane proteins and lipid diversity that may impact the activity of those proteins. Additionally, it is challenging to preserve the transmembrane protein native orientation, function, and mobility in SLBs. Here, we leverage the interaction between cell plasma membrane vesicles and polyelectrolyte brushes to create planar bilayers from cell plasma membrane vesicles that have budded from the cell surface. This approach promotes the direct incorporation of membrane proteins and other species into the planar bilayer without using detergent or reconstitution and preserves membrane constituents. Furthermore, the structure of the polyelectrolyte brush serves as a cushion between the planar bilayer and rigid supporting surface, limiting the interaction of the cytosolic domains of membrane proteins with this surface. Single particle tracking was used to analyze the motion of GPI-linked yellow fluorescent proteins (GPI-YFP) and neon-green fused transmembrane P2X2 receptors (P2X2-neon) and shows that this platform retains over 75% mobility of multipass transmembrane proteins in its native membrane environment. An enzyme accessibility assay confirmed that the protein orientation is preserved and results in the extracellular domain facing toward the bulk phase and the cytosolic side facing the support. Because the platform presented here retains the complexity of the cell plasma membrane and preserves protein orientation and mobility, it is a better representative mimic of native cell surfaces, which may find many applications in biological assays aimed at understanding cell membrane phenomena.

Efficient structure from motion for oblique UAV images based on maximal spanning tree expansion

NASA Astrophysics Data System (ADS)

Jiang, San; Jiang, Wanshou

2017-10-01

The primary contribution of this paper is an efficient Structure from Motion (SfM) solution for oblique unmanned aerial vehicle (UAV) images. First, an algorithm, considering spatial relationship constraints between image footprints, is designed for match pair selection with the assistance of UAV flight control data and oblique camera mounting angles. Second, a topological connection network (TCN), represented by an undirected weighted graph, is constructed from initial match pairs, which encodes the overlap areas and intersection angles into edge weights. Then, an algorithm, termed MST-Expansion, is proposed to extract the match graph from the TCN, where the TCN is first simplified by a maximum spanning tree (MST). By further analysis of the local structure in the MST, expansion operations are performed on the vertices of the MST for match graph enhancement, which is achieved by introducing critical connections in the expansion directions. Finally, guided by the match graph, an efficient SfM is proposed. Under extensive analysis and comparison, its performance is verified by using three oblique UAV datasets captured with different multi-camera systems. Experimental results demonstrate that the efficiency of image matching is improved, with speedup ratios ranging from 19 to 35, and competitive orientation accuracy is achieved from both relative bundle adjustment (BA) without GCPs (Ground Control Points) and absolute BA with GCPs. At the same time, images in the three datasets are successfully oriented. For the orientation of oblique UAV images, the proposed method can be a more efficient solution.

A constrained Delaunay discretization method for adaptively meshing highly discontinuous geological media

NASA Astrophysics Data System (ADS)

Wang, Yang; Ma, Guowei; Ren, Feng; Li, Tuo

2017-12-01

A constrained Delaunay discretization method is developed to generate high-quality doubly adaptive meshes of highly discontinuous geological media. Complex features such as three-dimensional discrete fracture networks (DFNs), tunnels, shafts, slopes, boreholes, water curtains, and drainage systems are taken into account in the mesh generation. The constrained Delaunay triangulation method is used to create adaptive triangular elements on planar fractures. Persson's algorithm (Persson, 2005), based on an analogy between triangular elements and spring networks, is enriched to automatically discretize a planar fracture into mesh points with varying density and smooth-quality gradient. The triangulated planar fractures are treated as planar straight-line graphs (PSLGs) to construct piecewise-linear complex (PLC) for constrained Delaunay tetrahedralization. This guarantees the doubly adaptive characteristic of the resulted mesh: the mesh is adaptive not only along fractures but also in space. The quality of elements is compared with the results from an existing method. It is verified that the present method can generate smoother elements and a better distribution of element aspect ratios. Two numerical simulations are implemented to demonstrate that the present method can be applied to various simulations of complex geological media that contain a large number of discontinuities.

Quasi-classical expansion of the star-triangle relation and integrable systems on quad-graphs

NASA Astrophysics Data System (ADS)

Bazhanov, Vladimir V.; Kels, Andrew P.; Sergeev, Sergey M.

2016-11-01

In this paper we give an overview of exactly solved edge-interaction models, where the spins are placed on sites of a planar lattice and interact through edges connecting the sites. We only consider the case of a single spin degree of freedom at each site of the lattice. The Yang-Baxter equation for such models takes a particular simple form called the star-triangle relation. Interestigly all known solutions of this relation can be obtained as particular cases of a single ‘master solution’, which is expressed through the elliptic gamma function and have continuous spins taking values on the circle. We show that in the low-temperature (or quasi-classical) limit these lattice models reproduce classical discrete integrable systems on planar graphs previously obtained and classified by Adler, Bobenko and Suris through the consistency-around-a-cube approach. We also discuss inversion relations, the physicical meaning of Baxter’s rapidity-independent parameter in the star-triangle relations and the invariance of the action of the classical systems under the star-triangle (or cube-flip) transformation of the lattice, which is a direct consequence of Baxter’s Z-invariance in the associated lattice models. Dedicated to Professor Rodney Baxter on the occasion of his 75th birthday.

Efficient, graph-based white matter connectivity from orientation distribution functions via multi-directional graph propagation

NASA Astrophysics Data System (ADS)

Boucharin, Alexis; Oguz, Ipek; Vachet, Clement; Shi, Yundi; Sanchez, Mar; Styner, Martin

2011-03-01

The use of regional connectivity measurements derived from diffusion imaging datasets has become of considerable interest in the neuroimaging community in order to better understand cortical and subcortical white matter connectivity. Current connectivity assessment methods are based on streamline fiber tractography, usually applied in a Monte-Carlo fashion. In this work we present a novel, graph-based method that performs a fully deterministic, efficient and stable connectivity computation. The method handles crossing fibers and deals well with multiple seed regions. The computation is based on a multi-directional graph propagation method applied to sampled orientation distribution function (ODF), which can be computed directly from the original diffusion imaging data. We show early results of our method on synthetic and real datasets. The results illustrate the potential of our method towards subjectspecific connectivity measurements that are performed in an efficient, stable and reproducible manner. Such individual connectivity measurements would be well suited for application in population studies of neuropathology, such as Autism, Huntington's Disease, Multiple Sclerosis or leukodystrophies. The proposed method is generic and could easily be applied to non-diffusion data as long as local directional data can be derived.

A tectorin-based matrix and planar cell polarity genes are required for normal collagen-fibril orientation in the developing tectorial membrane.

PubMed

Goodyear, Richard J; Lu, Xiaowei; Deans, Michael R; Richardson, Guy P

2017-11-01

The tectorial membrane is an extracellular structure of the cochlea. It develops on the surface of the auditory epithelium and contains collagen fibrils embedded in a tectorin-based matrix. The collagen fibrils are oriented radially with an apically directed slant - a feature considered crucial for hearing. To determine how this pattern is generated, collagen-fibril formation was examined in mice lacking a tectorin-based matrix, epithelial cilia or the planar cell polarity genes Vangl2 and Ptk7 In wild-type mice, collagen-fibril bundles appear within a tectorin-based matrix at E15.5 and, as fibril number rapidly increases, become co-aligned and correctly oriented. Epithelial width measurements and data from Kif3a cKO mice suggest, respectively, that radial stretch and cilia play little, if any, role in determining normal collagen-fibril orientation; however, evidence from tectorin-knockout mice indicates that confinement is important. PRICKLE2 distribution reveals the planar cell polarity axis in the underlying epithelium is organised along the length of the cochlea and, in mice in which this polarity is disrupted, the apically directed collagen offset is no longer observed. These results highlight the importance of the tectorin-based matrix and epithelial signals for precise collagen organisation in the tectorial membrane. © 2017. Published by The Company of Biologists Ltd.

Theory of third-order spectroscopic methods to extract detailed molecular orientational dynamics for planar surfaces and other uniaxial systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishida, Jun; Fayer, Michael D., E-mail: fayer@stanford.edu

Functionalized organic monolayers deposited on planar two-dimensional surfaces are important systems for studying ultrafast orientational motions and structures of interfacial molecules. Several studies have successfully observed the orientational relaxation of functionalized monolayers by fluorescence depolarization experiments and recently by polarization-resolved heterodyne detected vibrational transient grating (HDTG) experiments. In this article we provide a model-independent theory to extract orientational correlation functions unique to interfacial molecules and other uniaxial systems based on polarization-resolved resonant third-order spectroscopies, such as pump-probe spectroscopy, HDTG spectroscopy, and fluorescence depolarization experiment. It will be shown (in the small beam-crossing angle limit) that five measurements are necessary tomore » completely characterize the monolayer's motions: I{sub ∥}(t) and I{sub ⊥}(t) with the incident beams normal to the surface, I{sub ∥}(t) and I{sub ⊥}(t) with a non-zero incident angle, and a time averaged linear dichroism measurement. Once these measurements are performed, two orientational correlation functions corresponding to in-plane and out-of-plane motions are obtained. The procedure is applicable not only for monolayers on flat surfaces, but any samples with uniaxial symmetry such as uniaxial liquid crystals and aligned planar bilayers. The theory is valid regardless of the nature of the actual molecular motions on interface. We then apply the general results to wobbling-in-a-cone model, in which molecular motions are restricted to a limited range of angles. Within the context of the model, the cone angle, the tilt of the cone relative to the surface normal, and the orientational diffusion constant can be determined. The results are extended to describe analysis of experiments where the beams are not crossing in the small angle limit.« less

Massive Scale Cyber Traffic Analysis: A Driver for Graph Database Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joslyn, Cliff A.; Choudhury, S.; Haglin, David J.

2013-06-19

We describe the significance and prominence of network traffic analysis (TA) as a graph- and network-theoretical domain for advancing research in graph database systems. TA involves observing and analyzing the connections between clients, servers, hosts, and actors within IP networks, both at particular times and as extended over times. Towards that end, NetFlow (or more generically, IPFLOW) data are available from routers and servers which summarize coherent groups of IP packets flowing through the network. IPFLOW databases are routinely interrogated statistically and visualized for suspicious patterns. But the ability to cast IPFLOW data as a massive graph and query itmore » interactively, in order to e.g.\\ identify connectivity patterns, is less well advanced, due to a number of factors including scaling, and their hybrid nature combining graph connectivity and quantitative attributes. In this paper, we outline requirements and opportunities for graph-structured IPFLOW analytics based on our experience with real IPFLOW databases. Specifically, we describe real use cases from the security domain, cast them as graph patterns, show how to express them in two graph-oriented query languages SPARQL and Datalog, and use these examples to motivate a new class of "hybrid" graph-relational systems.« less

A graph-theory framework for evaluating landscape connectivity and conservation planning.

PubMed

Minor, Emily S; Urban, Dean L

2008-04-01

Connectivity of habitat patches is thought to be important for movement of genes, individuals, populations, and species over multiple temporal and spatial scales. We used graph theory to characterize multiple aspects of landscape connectivity in a habitat network in the North Carolina Piedmont (U.S.A). We compared this landscape with simulated networks with known topology, resistance to disturbance, and rate of movement. We introduced graph measures such as compartmentalization and clustering, which can be used to identify locations on the landscape that may be especially resilient to human development or areas that may be most suitable for conservation. Our analyses indicated that for songbirds the Piedmont habitat network was well connected. Furthermore, the habitat network had commonalities with planar networks, which exhibit slow movement, and scale-free networks, which are resistant to random disturbances. These results suggest that connectivity in the habitat network was high enough to prevent the negative consequences of isolation but not so high as to allow rapid spread of disease. Our graph-theory framework provided insight into regional and emergent global network properties in an intuitive and visual way and allowed us to make inferences about rates and paths of species movements and vulnerability to disturbance. This approach can be applied easily to assessing habitat connectivity in any fragmented or patchy landscape.

Orientation dependence of the dislocation microstructure in compressed body-centered cubic molybdenum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, S.; Wang, M.P.; Chen, C., E-mail: chench011-33@163.com

2014-05-01

The orientation dependence of the deformation microstructure has been investigated in commercial pure molybdenum. After deformation, the dislocation boundaries of compressed molybdenum can be classified, similar to that in face-centered cubic metals, into three types: dislocation cells (Type 2), and extended planar boundaries parallel to (Type 1) or not parallel to (Type 3) a (110) trace. However, it shows a reciprocal relationship between face-centered cubic metals and body-centered cubic metals on the orientation dependence of the deformation microstructure. The higher the strain, the finer the microstructure is and the smaller the inclination angle between extended planar boundaries and the compressionmore » axis is. - Highlights: • A reciprocal relationship between FCC metals and BCC metals is confirmed. • The dislocation boundaries can be classified into three types in compressed Mo. • The dislocation characteristic of different dislocation boundaries is different.« less

SimGraph: A Flight Simulation Data Visualization Workstation

NASA Technical Reports Server (NTRS)

Kaplan, Joseph A.; Kenney, Patrick S.

1997-01-01

Today's modern flight simulation research produces vast amounts of time sensitive data, making a qualitative analysis of the data difficult while it remains in a numerical representation. Therefore, a method of merging related data together and presenting it to the user in a more comprehensible format is necessary. Simulation Graphics (SimGraph) is an object-oriented data visualization software package that presents simulation data in animated graphical displays for easy interpretation. Data produced from a flight simulation is presented by SimGraph in several different formats, including: 3-Dimensional Views, Cockpit Control Views, Heads-Up Displays, Strip Charts, and Status Indicators. SimGraph can accommodate the addition of new graphical displays to allow the software to be customized to each user s particular environment. A new display can be developed and added to SimGraph without having to design a new application, allowing the graphics programmer to focus on the development of the graphical display. The SimGraph framework can be reused for a wide variety of visualization tasks. Although it was created for the flight simulation facilities at NASA Langley Research Center, SimGraph can be reconfigured to almost any data visualization environment. This paper describes the capabilities and operations of SimGraph.

Characterization of Adaptation by Morphology in a Planar Biological Network of Plasmodial Slime Mold

NASA Astrophysics Data System (ADS)

Ito, Masateru; Okamoto, Riki; Takamatsu, Atsuko

2011-07-01

Growth processes of a planar biological network of plasmodium of a true slime mold, Physarum polycephalum, were analyzed quantitatively. The plasmodium forms a transportation network through which protoplasm conveys nutrients, oxygen, and cellular organelles similarly to blood in a mammalian vascular network. To analyze the network structure, vertices were defined at tube bifurcation points. Then edges were defined for the tubes connecting both end vertices. Morphological analysis was attempted along with conventional topological analysis, revealing that the growth process of the plasmodial network structure depends on environmental conditions. In an attractive condition, the network is a polygonal lattice with more than six edges per vertex at the early stage and the hexagonal lattice at a later stage. Through all growing stages, the tube structure was not highly developed but an unstructured protoplasmic thin sheet was dominantly formed. The network size is small. In contrast, in the repulsive condition, the network is a mixture of polygonal lattice and tree-graph. More specifically, the polygonal lattice has more than six edges per vertex in the early stage, then a tree-graph structure is added to the lattice network at a later stage. The thick tube structure was highly developed. The network size, in the meaning of Euclidean distance but not topological one, grows considerably. Finally, the biological meaning of the environment-dependent network structure in the plasmodium is discussed.

Spectral and cyclic voltammetric studies on some intramolecularly hydrogen bonded arylhydrazones: Crystal and molecular structure of 2-(2-(3-nitrophenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione

NASA Astrophysics Data System (ADS)

Sethukumar, A.; Arul Prakasam, B.

2010-01-01

A series of arylhydrazone derivatives ( 1- 7) were prepared by the coupling of acetylacetone/dimedone with respective aromatic diazonium salts and characterized by IR, 1H and 13C NMR spectra. The IR and NMR spectral data clearly manifests the effective intramolecular hydrogen bonding in all the cases. Cyclic voltammetric studies certainly indicate that in all the cases the reduced center is C dbnd N bond of hydrazonic moiety. The single crystal X-ray structural analysis of 2-(2-(3-nitrophenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione ( 6) is also reported. Single crystal X-ray analysis of 6 evidences the intramolecular hydrogen bonding with the N(2)⋯O(4) distance of 2.642(15) Å, which can be designated as S(6) according to Etter's graph nomenclature. The cyclohexane ring conformation in the molecule ( 6) can be described as an envelope. RAHB studies suggest that the resonance assistance for hydrogen bonding is significantly reduced for the compound ( 6) due to the non-planarity of the six atoms which are involved in resonant cycle S(6) of Etter's graph. The planarity of the resonant cycle S(6) is very much disturbed by the conformational requirement of the cyclohexane ring and hence RAHB concept is less operative in this case.

Membrane Protein Mobility and Orientation Preserved in Supported Bilayers Created Directly from Cell Plasma Membrane Blebs.

PubMed

Richards, Mark J; Hsia, Chih-Yun; Singh, Rohit R; Haider, Huma; Kumpf, Julia; Kawate, Toshimitsu; Daniel, Susan

2016-03-29

Membrane protein interactions with lipids are crucial for their native biological behavior, yet traditional characterization methods are often carried out on purified protein in the absence of lipids. We present a simple method to transfer membrane proteins expressed in mammalian cells to an assay-friendly, cushioned, supported lipid bilayer platform using cell blebs as an intermediate. Cell blebs, expressing either GPI-linked yellow fluorescent proteins or neon-green fused transmembrane P2X2 receptors, were induced to rupture on glass surfaces using PEGylated lipid vesicles, which resulted in planar supported membranes with over 50% mobility for multipass transmembrane proteins and over 90% for GPI-linked proteins. Fluorescent proteins were tracked, and their diffusion in supported bilayers characterized, using single molecule tracking and moment scaling spectrum (MSS) analysis. Diffusion was characterized for individual proteins as either free or confined, revealing details of the local lipid membrane heterogeneity surrounding the protein. A particularly useful result of our bilayer formation process is the protein orientation in the supported planar bilayer. For both the GPI-linked and transmembrane proteins used here, an enzymatic assay revealed that protein orientation in the planar bilayer results in the extracellular domains facing toward the bulk, and that the dominant mode of bleb rupture is via the "parachute" mechanism. Mobility, orientation, and preservation of the native lipid environment of the proteins using cell blebs offers advantages over proteoliposome reconstitution or disrupted cell membrane preparations, which necessarily result in significant scrambling of protein orientation and typically immobilized membrane proteins in SLBs. The bleb-based bilayer platform presented here is an important step toward integrating membrane proteomic studies on chip, especially for future studies aimed at understanding fundamental effects of lipid interactions on protein activity and the roles of membrane proteins in disease pathways.

Students' meaning making in science: solving energy resource problems in virtual worlds combined with spreadsheets to develop graphs

NASA Astrophysics Data System (ADS)

Krange, Ingeborg; Arnseth, Hans Christian

2012-09-01

The aim of this study is to scrutinize the characteristics of conceptual meaning making when students engage with virtual worlds in combination with a spreadsheet with the aim to develop graphs. We study how these tools and the representations they contain or enable students to construct serve to influence their understanding of energy resource consumption. The data were gathered in 1st grade upper-secondary science classes and they constitute the basis for the interaction analysis of students' meaning making with representations. Our analyses demonstrate the difficulties involved in developing students' orientation toward more conceptual orientations to representations of the knowledge domain. Virtual worlds do not in themselves represent a solution to this problem.

Fundamental and practical limits of planar tracking solar concentrators.

PubMed

Grede, Alex J; Price, Jared S; Giebink, Noel C

2016-12-26

Planar microtracking provides an alternate paradigm for solar concentration that offers the possibility of realizing high-efficiency embedded concentrating photovoltaic systems in the form factor of standard photovoltaic panels. Here, we investigate the thermodynamic limit of planar tracking optical concentrators and establish that they can, in principal, achieve the sine limit of their orientationally-tracked counterparts provided that the receiver translates a minimum distance set by the field of view half-angle. We develop a phase space methodology to optimize practical planar tracking concentrators and apply it to the design of a two surface, catadioptric system that operates with > 90% optical efficiency over a 140° field of view at geometric gains exceeding 1000×. These results provide a reference point for subsequent developments in the field and indicate that planar microtracking can achieve the high optical concentration ratio required in commercial concentrating photovoltaic systems.

Clustering and negative feedback by endocytosis in planar cell polarity signaling is modulated by ubiquitinylation of prickle.

PubMed

Cho, Bomsoo; Pierre-Louis, Gandhy; Sagner, Andreas; Eaton, Suzanne; Axelrod, Jeffrey D

2015-05-01

The core components of the planar cell polarity (PCP) signaling system, including both transmembrane and peripheral membrane associated proteins, form asymmetric complexes that bridge apical intercellular junctions. While these can assemble in either orientation, coordinated cell polarization requires the enrichment of complexes of a given orientation at specific junctions. This might occur by both positive and negative feedback between oppositely oriented complexes, and requires the peripheral membrane associated PCP components. However, the molecular mechanisms underlying feedback are not understood. We find that the E3 ubiquitin ligase complex Cullin1(Cul1)/SkpA/Supernumerary limbs(Slimb) regulates the stability of one of the peripheral membrane components, Prickle (Pk). Excess Pk disrupts PCP feedback and prevents asymmetry. We show that Pk participates in negative feedback by mediating internalization of PCP complexes containing the transmembrane components Van Gogh (Vang) and Flamingo (Fmi), and that internalization is activated by oppositely oriented complexes within clusters. Pk also participates in positive feedback through an unknown mechanism promoting clustering. Our results therefore identify a molecular mechanism underlying generation of asymmetry in PCP signaling.

Physical and Genetic Mechanisms Guiding the Evolution and Development of Dendritic, Flapping Insect-Wings

DTIC Science & Technology

2010-04-12

computer graphics, to music . Map L systems [2, 6, 7] extend the parallel rewriting in L systems to planar graphs with cycles, called maps [8]. The maps...carbon. For easy of reading , in the results below the mass is represented by the percentage carbon laminate coverage. As explained previously, the...previously, that value can be read in the left vertical axis. There are nine designs in the Pareto front. Depending on design goals any of these individuals

If BZ medium did spanning trees these would be the same trees as Physarum built

NASA Astrophysics Data System (ADS)

Adamatzky, Andrew

2009-03-01

A sub-excitable Belousov-Zhabotinsky (BZ) medium exhibits self-localized wave-fragments which may travel for relatively long time preserving their shape. Using Oregonator model of the BZ medium we imitate foraging behavior of a true slime mold, Physarum polycephalum, on a nutrient-poor substrate. We show that given erosion post-processing operations the BZ medium can approximate a spanning tree of a planar set and thus is computationally equivalent to Physarum in the domain of proximity graph construction.

Reactome graph database: Efficient access to complex pathway data

PubMed Central

Korninger, Florian; Viteri, Guilherme; Marin-Garcia, Pablo; Ping, Peipei; Wu, Guanming; Stein, Lincoln; D’Eustachio, Peter

2018-01-01

Reactome is a free, open-source, open-data, curated and peer-reviewed knowledgebase of biomolecular pathways. One of its main priorities is to provide easy and efficient access to its high quality curated data. At present, biological pathway databases typically store their contents in relational databases. This limits access efficiency because there are performance issues associated with queries traversing highly interconnected data. The same data in a graph database can be queried more efficiently. Here we present the rationale behind the adoption of a graph database (Neo4j) as well as the new ContentService (REST API) that provides access to these data. The Neo4j graph database and its query language, Cypher, provide efficient access to the complex Reactome data model, facilitating easy traversal and knowledge discovery. The adoption of this technology greatly improved query efficiency, reducing the average query time by 93%. The web service built on top of the graph database provides programmatic access to Reactome data by object oriented queries, but also supports more complex queries that take advantage of the new underlying graph-based data storage. By adopting graph database technology we are providing a high performance pathway data resource to the community. The Reactome graph database use case shows the power of NoSQL database engines for complex biological data types. PMID:29377902

Reactome graph database: Efficient access to complex pathway data.

PubMed

Fabregat, Antonio; Korninger, Florian; Viteri, Guilherme; Sidiropoulos, Konstantinos; Marin-Garcia, Pablo; Ping, Peipei; Wu, Guanming; Stein, Lincoln; D'Eustachio, Peter; Hermjakob, Henning

2018-01-01

Reactome is a free, open-source, open-data, curated and peer-reviewed knowledgebase of biomolecular pathways. One of its main priorities is to provide easy and efficient access to its high quality curated data. At present, biological pathway databases typically store their contents in relational databases. This limits access efficiency because there are performance issues associated with queries traversing highly interconnected data. The same data in a graph database can be queried more efficiently. Here we present the rationale behind the adoption of a graph database (Neo4j) as well as the new ContentService (REST API) that provides access to these data. The Neo4j graph database and its query language, Cypher, provide efficient access to the complex Reactome data model, facilitating easy traversal and knowledge discovery. The adoption of this technology greatly improved query efficiency, reducing the average query time by 93%. The web service built on top of the graph database provides programmatic access to Reactome data by object oriented queries, but also supports more complex queries that take advantage of the new underlying graph-based data storage. By adopting graph database technology we are providing a high performance pathway data resource to the community. The Reactome graph database use case shows the power of NoSQL database engines for complex biological data types.

ScaffoldScaffolder: solving contig orientation via bidirected to directed graph reduction.

PubMed

Bodily, Paul M; Fujimoto, M Stanley; Snell, Quinn; Ventura, Dan; Clement, Mark J

2016-01-01

The contig orientation problem, which we formally define as the MAX-DIR problem, has at times been addressed cursorily and at times using various heuristics. In setting forth a linear-time reduction from the MAX-CUT problem to the MAX-DIR problem, we prove the latter is NP-complete. We compare the relative performance of a novel greedy approach with several other heuristic solutions. Our results suggest that our greedy heuristic algorithm not only works well but also outperforms the other algorithms due to the nature of scaffold graphs. Our results also demonstrate a novel method for identifying inverted repeats and inversion variants, both of which contradict the basic single-orientation assumption. Such inversions have previously been noted as being difficult to detect and are directly involved in the genetic mechanisms of several diseases. http://bioresearch.byu.edu/scaffoldscaffolder. paulmbodily@gmail.com Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Energy level alignment at planar organic heterojunctions: influence of contact doping and molecular orientation.

PubMed

Opitz, Andreas

2017-04-05

Planar organic heterojunctions are widely used in photovoltaic cells, light-emitting diodes, and bilayer field-effect transistors. The energy level alignment in the devices plays an important role in obtaining the aspired gap arrangement. Additionally, the π-orbital overlap between the involved molecules defines e.g. the charge-separation efficiency in solar cells due to charge-transfer effects. To account for both aspects, direct/inverse photoemission spectroscopy and near edge x-ray absorption fine structure spectroscopy were used to determine the energy level landscape and the molecular orientation at prototypical planar organic heterojunctions. The combined experimental approach results in a comprehensive model for the electronic and morphological characteristics of the interface between the two investigated molecular semiconductors. Following an introduction on heterojunctions used in devices and on energy levels of organic materials, the energy level alignment of planar organic heterojunctions will be discussed. The observed energy landscape is always determined by the individual arrangement between the energy levels of the molecules and the work function of the electrode. This might result in contact doping due to Fermi level pinning at the electrode for donor/acceptor heterojunctions, which also improves the solar cell efficiency. This pinning behaviour can be observed across an unpinned interlayer and results in charge accumulation at the donor/acceptor interface, depending on the transport levels of the respective organic semiconductors. Moreover, molecular orientation will affect the energy levels because of the anisotropy in ionisation energy and electron affinity and is influenced by the structural compatibility of the involved molecules at the heterojunction. High structural compatibility leads to π-orbital stacking between different molecules at a heterojunction, which is of additional interest for photovoltaic active interfaces and for ground-state charge-transfer.

GOGrapher: A Python library for GO graph representation and analysis.

PubMed

Muller, Brian; Richards, Adam J; Jin, Bo; Lu, Xinghua

2009-07-07

The Gene Ontology is the most commonly used controlled vocabulary for annotating proteins. The concepts in the ontology are organized as a directed acyclic graph, in which a node corresponds to a biological concept and a directed edge denotes the parent-child semantic relationship between a pair of terms. A large number of protein annotations further create links between proteins and their functional annotations, reflecting the contemporary knowledge about proteins and their functional relationships. This leads to a complex graph consisting of interleaved biological concepts and their associated proteins. What is needed is a simple, open source library that provides tools to not only create and view the Gene Ontology graph, but to analyze and manipulate it as well. Here we describe the development and use of GOGrapher, a Python library that can be used for the creation, analysis, manipulation, and visualization of Gene Ontology related graphs. An object-oriented approach was adopted to organize the hierarchy of the graphs types and associated classes. An Application Programming Interface is provided through which different types of graphs can be pragmatically created, manipulated, and visualized. GOGrapher has been successfully utilized in multiple research projects, e.g., a graph-based multi-label text classifier for protein annotation. The GOGrapher project provides a reusable programming library designed for the manipulation and analysis of Gene Ontology graphs. The library is freely available for the scientific community to use and improve.

Dynamics of collision of a vortex ring and a planar surface

NASA Astrophysics Data System (ADS)

McErlean, Michael; Krane, Michael; Fontaine, Arnold

2008-11-01

The dynamics of the impact between a vortex ring and a planar surface is presented. The vortex rings, generated by piston injection of a slug of water into a quiescent water tank, collide with a surface oriented normally to the ring's direction of travel. The time evolution of both the force imparted to a planar surface and the wall pressure are presented. These are supplemented by DPIV measurements of the evolution of ring strength and structure, before and during impact. The relation between changes in ring structure during collision and the waveforms of impact force and wall pressure will be discussed.

Efficient planar heterojunction perovskite solar cells employing graphene oxide as hole conductor.

PubMed

Wu, Zhongwei; Bai, Sai; Xiang, Jian; Yuan, Zhongcheng; Yang, Yingguo; Cui, Wei; Gao, Xingyu; Liu, Zhuang; Jin, Yizheng; Sun, Baoquan

2014-09-21

Graphene oxide (GO) is employed as a hole conductor in inverted planar heterojunction perovskite solar cells, and the devices with CH₃NH₃PbI₃-xClx as absorber achieve an efficiency of over 12%. The perovskite film grown on GO exhibits enhanced crystallization, high surface coverage ratio as well as preferred in-plane orientation of the (110) plane. Efficient hole extraction from the perovskite to GO is demonstrated.

Chiral limit of N = 4 SYM and ABJM and integrable Feynman graphs

NASA Astrophysics Data System (ADS)

Caetano, João; Gürdoğan, Ömer; Kazakov, Vladimir

2018-03-01

We consider a special double scaling limit, recently introduced by two of the authors, combining weak coupling and large imaginary twist, for the γ-twisted N = 4 SYM theory. We also establish the analogous limit for ABJM theory. The resulting non-gauge chiral 4D and 3D theories of interacting scalars and fermions are integrable in the planar limit. In spite of the breakdown of conformality by double-trace interactions, most of the correlators for local operators of these theories are conformal, with non-trivial anomalous dimensions defined by specific, integrable Feynman diagrams. We discuss the details of this diagrammatics. We construct the doubly-scaled asymptotic Bethe ansatz (ABA) equations for multi-magnon states in these theories. Each entry of the mixing matrix of local conformal operators in the simplest of these theories — the bi-scalar model in 4D and tri-scalar model in 3D — is given by a single Feynman diagram at any given loop order. The related diagrams are in principle computable, up to a few scheme dependent constants, by integrability methods (quantum spectral curve or ABA). These constants should be fixed from direct computations of a few simplest graphs. This integrability-based method is advocated to be able to provide information about some high loop order graphs which are hardly computable by other known methods. We exemplify our approach with specific five-loop graphs.

A Comparative Evaluation of the Effects of the Implementation of the Production Oriented Maintenance Organization (POMO) on Aircraft Maintenance

DTIC Science & Technology

1978-09-01

Division AREA & WORK UNIT NUMBERS School of Systems and Logistics’ Air Force Institute of Technology,WPAFB,OH II. CONTROLLING OFFICE NAME AND ADDRESS 12 ...STRUCTURE) ............. ................ 9) 12 . SUMMARY OF ALL ANALYSIS RESUILT,"S ........ ........ 94 vii i LIST OF FIGURES Figure Page 1. Deputy...ness Rate (Variable 4) .... ............ ... 81 12 . Graph of Data Values for Abort Rate (Variable 5 e) . ..................... 82 13. Graph of Data

Subfactors of Index Less Than 5, Part 3: Quadruple Points

NASA Astrophysics Data System (ADS)

Izumi, Masaki; Jones, Vaughan F. R.; Morrison, Scott; Snyder, Noah

2012-12-01

One major obstacle in extending the classification of small index subfactors beyond {3 +sqrt{3}} is the appearance of infinite families of candidate principal graphs with 4-valent vertices (in particular, the "weeds" {{Q}} and {{Q}'} from Part 1 (Morrison and Snyder in Commun. Math. Phys., doi: 10.1007/s00220-012-1426-y, 2012). Thus instead of using triple point obstructions to eliminate candidate graphs, we need to develop new quadruple point obstructions. In this paper we prove two quadruple point obstructions. The first uses quadratic tangles techniques and eliminates the weed {{Q}'} immediately. The second uses connections, and when combined with an additional number theoretic argument it eliminates both weeds {{Q}} and {{Q}'} . Finally, we prove the uniqueness (up to taking duals) of the 3311 Goodman-de la Harpe-Jones subfactor using a combination of planar algebra techniques and connections.

Planar cell polarity signaling coordinates oriented cell division and cell rearrangement in clonally expanding growth plate cartilage.

PubMed

Li, Yuwei; Li, Ang; Junge, Jason; Bronner, Marianne

2017-10-10

Both oriented cell divisions and cell rearrangements are critical for proper embryogenesis and organogenesis. However, little is known about how these two cellular events are integrated. Here we examine the linkage between these processes in chick limb cartilage. By combining retroviral-based multicolor clonal analysis with live imaging, the results show that single chondrocyte precursors can generate both single-column and multi-column clones through oriented division followed by cell rearrangements. Focusing on single column formation, we show that this stereotypical tissue architecture is established by a pivot-like process between sister cells. After mediolateral cell division, N-cadherin is enriched in the post-cleavage furrow; then one cell pivots around the other, resulting in stacking into a column. Perturbation analyses demonstrate that planar cell polarity signaling enables cells to pivot in the direction of limb elongation via this N-cadherin-mediated coupling. Our work provides new insights into the mechanisms generating appropriate tissue architecture of limb skeleton.

Planar cell polarity signaling coordinates oriented cell division and cell rearrangement in clonally expanding growth plate cartilage

PubMed Central

Li, Yuwei; Li, Ang; Junge, Jason

2017-01-01

Both oriented cell divisions and cell rearrangements are critical for proper embryogenesis and organogenesis. However, little is known about how these two cellular events are integrated. Here we examine the linkage between these processes in chick limb cartilage. By combining retroviral-based multicolor clonal analysis with live imaging, the results show that single chondrocyte precursors can generate both single-column and multi-column clones through oriented division followed by cell rearrangements. Focusing on single column formation, we show that this stereotypical tissue architecture is established by a pivot-like process between sister cells. After mediolateral cell division, N-cadherin is enriched in the post-cleavage furrow; then one cell pivots around the other, resulting in stacking into a column. Perturbation analyses demonstrate that planar cell polarity signaling enables cells to pivot in the direction of limb elongation via this N-cadherin-mediated coupling. Our work provides new insights into the mechanisms generating appropriate tissue architecture of limb skeleton. PMID:28994649

Integration of prior knowledge into dense image matching for video surveillance

NASA Astrophysics Data System (ADS)

Menze, M.; Heipke, C.

2014-08-01

Three-dimensional information from dense image matching is a valuable input for a broad range of vision applications. While reliable approaches exist for dedicated stereo setups they do not easily generalize to more challenging camera configurations. In the context of video surveillance the typically large spatial extent of the region of interest and repetitive structures in the scene render the application of dense image matching a challenging task. In this paper we present an approach that derives strong prior knowledge from a planar approximation of the scene. This information is integrated into a graph-cut based image matching framework that treats the assignment of optimal disparity values as a labelling task. Introducing the planar prior heavily reduces ambiguities together with the search space and increases computational efficiency. The results provide a proof of concept of the proposed approach. It allows the reconstruction of dense point clouds in more general surveillance camera setups with wider stereo baselines.

Maintained expression of the planar cell polarity molecule Vangl2 and reformation of hair cell orientation in the regenerating inner ear.

PubMed

Warchol, Mark E; Montcouquiol, Mireille

2010-09-01

The avian inner ear possesses a remarkable ability to regenerate sensory hair cells after ototoxic injury. Regenerated hair cells possess phenotypes and innervation that are similar to those found in the undamaged ear, but little is known about the signaling pathways that guide hair cell differentiation during the regenerative process. The aim of the present study was to examine the factors that specify the orientation of hair cell stereocilia bundles during regeneration. Using organ cultures of the chick utricle, we show that hair cells are properly oriented after having regenerated entirely in vitro and that orientation is not affected by surgical removal of the striolar reversal zone. These results suggest that the orientation of regenerating stereocilia is not guided by the release of a diffusible morphogen from the striolar reversal zone but is specified locally within the regenerating sensory organ. In order to determine the nature of the reorientation cues, we examined the expression patterns of the core planar cell polarity molecule Vangl2 in the normal and regenerating utricle. We found that Vangl2 is asymmetrically expressed on cells within the sensory epithelium and that this expression pattern is maintained after ototoxic injury and throughout regeneration. Notably, treatment with a small molecule inhibitor of c-Jun-N-terminal kinase disrupted the orientation of regenerated hair cells. Both of these results are consistent with the hypothesis that noncanonical Wnt signaling guides hair cell orientation during regeneration.

Magneto-optical visualization of three spatial components of inhomogeneous stray fields

NASA Astrophysics Data System (ADS)

Ivanov, V. E.

2012-08-01

The article deals with the physical principles of magneto-optical visualization (MO) of three spatial components of inhomogeneous stray fields with the help of FeCo metal indicator films in the longitudinal Kerr effect geometry. The inhomogeneous field is created by permanent magnets. Both p- and s-polarization light is used for obtaining MO images with their subsequent summing, subtracting and digitizing. As a result, the MO images and corresponding intensity coordinate dependences reflecting the distributions of the horizontal and vertical magnetization components in pure form have been obtained. Modeling of both the magnetization distribution in the indicator film and the corresponding MO images shows that corresponding to polar sensitivity the intensity is proportional to the normal field component, which permits normal field component mapping. Corresponding to longitudinal sensitivity, the intensity of the MO images reflects the angular distribution of the planar field component. MO images have singular points in which the planar component is zero and their movement under an externally homogeneous planar field permits obtaining of additional information on the two planar components of the field under study. The intensity distribution character in the vicinity of sources and sinks (singular points) remains the same under different orientations of the light incidence plane. The change of incident plane orientation by π/2 alters the distribution pattern in the vicinity of the saddle points.

Imaging system for cardiac planar imaging using a dedicated dual-head gamma camera

DOEpatents

Majewski, Stanislaw [Morgantown, VA; Umeno, Marc M [Woodinville, WA

2011-09-13

A cardiac imaging system employing dual gamma imaging heads co-registered with one another to provide two dynamic simultaneous views of the heart sector of a patient torso. A first gamma imaging head is positioned in a first orientation with respect to the heart sector and a second gamma imaging head is positioned in a second orientation with respect to the heart sector. An adjustment arrangement is capable of adjusting the distance between the separate imaging heads and the angle between the heads. With the angle between the imaging heads set to 180 degrees and operating in a range of 140-159 keV and at a rate of up to 500kHz, the imaging heads are co-registered to produce simultaneous dynamic recording of two stereotactic views of the heart. The use of co-registered imaging heads maximizes the uniformity of detection sensitivity of blood flow in and around the heart over the whole heart volume and minimizes radiation absorption effects. A normalization/image fusion technique is implemented pixel-by-corresponding pixel to increase signal for any cardiac region viewed in two images obtained from the two opposed detector heads for the same time bin. The imaging system is capable of producing enhanced first pass studies, bloodpool studies including planar, gated and non-gated EKG studies, planar EKG perfusion studies, and planar hot spot imaging.

Hierarchical coefficient of a multifractal based network

NASA Astrophysics Data System (ADS)

Moreira, Darlan A.; Lucena, Liacir dos Santos; Corso, Gilberto

2014-02-01

The hierarchical property for a general class of networks stands for a power-law relation between clustering coefficient, CC and connectivity k: CC∝kβ. This relation is empirically verified in several biologic and social networks, as well as in random and deterministic network models, in special for hierarchical networks. In this work we show that the hierarchical property is also present in a Lucena network. To create a Lucena network we use the dual of a multifractal lattice ML, the vertices are the sites of the ML and links are established between neighbouring lattices, therefore this network is space filling and planar. Besides a Lucena network shows a scale-free distribution of connectivity. We deduce a relation for the maximal local clustering coefficient CCimax of a vertex i in a planar graph. This condition expresses that the number of links among neighbour, N△, of a vertex i is equal to its connectivity ki, that means: N△=ki. The Lucena network fulfils the condition N△≃ki independent of ki and the anisotropy of ML. In addition, CCmax implies the threshold β=1 for the hierarchical property for any scale-free planar network.

Fingerprint recognition system by use of graph matching

NASA Astrophysics Data System (ADS)

Shen, Wei; Shen, Jun; Zheng, Huicheng

2001-09-01

Fingerprint recognition is an important subject in biometrics to identify or verify persons by physiological characteristics, and has found wide applications in different domains. In the present paper, we present a finger recognition system that combines singular points and structures. The principal steps of processing in our system are: preprocessing and ridge segmentation, singular point extraction and selection, graph representation, and finger recognition by graphs matching. Our fingerprint recognition system is implemented and tested for many fingerprint images and the experimental result are satisfactory. Different techniques are used in our system, such as fast calculation of orientation field, local fuzzy dynamical thresholding, algebraic analysis of connections and fingerprints representation and matching by graphs. Wed find that for fingerprint database that is not very large, the recognition rate is very high even without using a prior coarse category classification. This system works well for both one-to-few and one-to-many problems.

Browsing schematics: Query-filtered graphs with context nodes

NASA Technical Reports Server (NTRS)

Ciccarelli, Eugene C.; Nardi, Bonnie A.

1988-01-01

The early results of a research project to create tools for building interfaces to intelligent systems on the NASA Space Station are reported. One such tool is the Schematic Browser which helps users engaged in engineering problem solving find and select schematics from among a large set. Users query for schematics with certain components, and the Schematic Browser presents a graph whose nodes represent the schematics with those components. The query greatly reduces the number of choices presented to the user, filtering the graph to a manageable size. Users can reformulate and refine the query serially until they locate the schematics of interest. To help users maintain orientation as they navigate a large body of data, the graph also includes nodes that are not matches but provide global and local context for the matching nodes. Context nodes include landmarks, ancestors, siblings, children and previous matches.

Optimization of beam orientation in radiotherapy using planar geometry

NASA Astrophysics Data System (ADS)

Haas, O. C. L.; Burnham, K. J.; Mills, J. A.

1998-08-01

This paper proposes a new geometrical formulation of the coplanar beam orientation problem combined with a hybrid multiobjective genetic algorithm. The approach is demonstrated by optimizing the beam orientation in two dimensions, with the objectives being formulated using planar geometry. The traditional formulation of the objectives associated with the organs at risk has been modified to account for the use of complex dose delivery techniques such as beam intensity modulation. The new algorithm attempts to replicate the approach of a treatment planner whilst reducing the amount of computation required. Hybrid genetic search operators have been developed to improve the performance of the genetic algorithm by exploiting problem-specific features. The multiobjective genetic algorithm is formulated around the concept of Pareto optimality which enables the algorithm to search in parallel for different objectives. When the approach is applied without constraining the number of beams, the solution produces an indication of the minimum number of beams required. It is also possible to obtain non-dominated solutions for various numbers of beams, thereby giving the clinicians a choice in terms of the number of beams as well as in the orientation of these beams.

GOGrapher: A Python library for GO graph representation and analysis

PubMed Central

Muller, Brian; Richards, Adam J; Jin, Bo; Lu, Xinghua

2009-01-01

Background The Gene Ontology is the most commonly used controlled vocabulary for annotating proteins. The concepts in the ontology are organized as a directed acyclic graph, in which a node corresponds to a biological concept and a directed edge denotes the parent-child semantic relationship between a pair of terms. A large number of protein annotations further create links between proteins and their functional annotations, reflecting the contemporary knowledge about proteins and their functional relationships. This leads to a complex graph consisting of interleaved biological concepts and their associated proteins. What is needed is a simple, open source library that provides tools to not only create and view the Gene Ontology graph, but to analyze and manipulate it as well. Here we describe the development and use of GOGrapher, a Python library that can be used for the creation, analysis, manipulation, and visualization of Gene Ontology related graphs. Findings An object-oriented approach was adopted to organize the hierarchy of the graphs types and associated classes. An Application Programming Interface is provided through which different types of graphs can be pragmatically created, manipulated, and visualized. GOGrapher has been successfully utilized in multiple research projects, e.g., a graph-based multi-label text classifier for protein annotation. Conclusion The GOGrapher project provides a reusable programming library designed for the manipulation and analysis of Gene Ontology graphs. The library is freely available for the scientific community to use and improve. PMID:19583843

Mitral Valve Chordae Tendineae: Topological and Geometrical Characterization.

PubMed

Khalighi, Amir H; Drach, Andrew; Bloodworth, Charles H; Pierce, Eric L; Yoganathan, Ajit P; Gorman, Robert C; Gorman, Joseph H; Sacks, Michael S

2017-02-01

Mitral valve (MV) closure depends upon the proper function of each component of the valve apparatus, which includes the annulus, leaflets, and chordae tendineae (CT). Geometry plays a major role in MV mechanics and thus highly impacts the accuracy of computational models simulating MV function and repair. While the physiological geometry of the leaflets and annulus have been previously investigated, little effort has been made to quantitatively and objectively describe CT geometry. The CT constitute a fibrous tendon-like structure projecting from the papillary muscles (PMs) to the leaflets, thereby evenly distributing the loads placed on the MV during closure. Because CT play a major role in determining the shape and stress state of the MV as a whole, their geometry must be well characterized. In the present work, a novel and comprehensive investigation of MV CT geometry was performed to more fully quantify CT anatomy. In vitro micro-tomography 3D images of ovine MVs were acquired, segmented, then analyzed using a curve-skeleton transform. The resulting data was used to construct B-spline geometric representations of the CT structures, enriched with a continuous field of cross-sectional area (CSA) data. Next, Reeb graph models were developed to analyze overall topological patterns, along with dimensional attributes such as segment lengths, 3D orientations, and CSA. Reeb graph results revealed that the topology of ovine MV CT followed a full binary tree structure. Moreover, individual chords are mostly planar geometries that together form a 3D load-bearing support for the MV leaflets. We further demonstrated that, unlike flow-based branching patterns, while individual CT branches became thinner as they propagated further away from the PM heads towards the leaflets, the total CSA almost doubled. Overall, our findings indicate a certain level of regularity in structure, and suggest that population-based MV CT geometric models can be generated to improve current MV repair procedures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fetterly, K; Mathew, V

Purpose: Transcatheter aortic valve replacement (TAVR) procedures provide a method to implant a prosthetic aortic valve via a minimallyinvasive, catheter-based procedure. TAVR procedures require use of interventional fluoroscopy c-arm projection angles which are aligned with the aortic valve plane to minimize prosthetic valve positioning error due to x-ray imaging parallax. The purpose of this work is to calculate the continuous range of interventional fluoroscopy c-arm projection angles which are aligned with the aortic valve plane from a single planar image of a valvuloplasty balloon inflated across the aortic valve. Methods: Computational methods to measure the 3D angular orientation of themore » aortic valve were developed. Required inputs include a planar x-ray image of a known valvuloplasty balloon inflated across the aortic valve and specifications of x-ray imaging geometry from the DICOM header of the image. A-priori knowledge of the species-specific typical range of aortic orientation is required to specify the sign of the angle of the long axis of the balloon with respect to the x-ray beam. The methods were validated ex-vivo and in a live pig. Results: Ex-vivo experiments demonstrated that the angular orientation of a stationary inflated valvuloplasty balloon can be measured with precision less than 1 degree. In-vivo pig experiments demonstrated that cardiac motion contributed to measurement variability, with precision less than 3 degrees. Error in specification of x-ray geometry directly influences measurement accuracy. Conclusion: This work demonstrates that the 3D angular orientation of the aortic valve can be calculated precisely from a planar image of a valvuloplasty balloon inflated across the aortic valve and known x-ray geometry. This method could be used to determine appropriate c-arm angular projections during TAVR procedures to minimize x-ray imaging parallax and thereby minimize prosthetic valve positioning errors.« less

A systematic composite service design modeling method using graph-based theory.

PubMed

Elhag, Arafat Abdulgader Mohammed; Mohamad, Radziah; Aziz, Muhammad Waqar; Zeshan, Furkh

2015-01-01

The composite service design modeling is an essential process of the service-oriented software development life cycle, where the candidate services, composite services, operations and their dependencies are required to be identified and specified before their design. However, a systematic service-oriented design modeling method for composite services is still in its infancy as most of the existing approaches provide the modeling of atomic services only. For these reasons, a new method (ComSDM) is proposed in this work for modeling the concept of service-oriented design to increase the reusability and decrease the complexity of system while keeping the service composition considerations in mind. Furthermore, the ComSDM method provides the mathematical representation of the components of service-oriented design using the graph-based theoryto facilitate the design quality measurement. To demonstrate that the ComSDM method is also suitable for composite service design modeling of distributed embedded real-time systems along with enterprise software development, it is implemented in the case study of a smart home. The results of the case study not only check the applicability of ComSDM, but can also be used to validate the complexity and reusability of ComSDM. This also guides the future research towards the design quality measurement such as using the ComSDM method to measure the quality of composite service design in service-oriented software system.

A Systematic Composite Service Design Modeling Method Using Graph-Based Theory

PubMed Central

Elhag, Arafat Abdulgader Mohammed; Mohamad, Radziah; Aziz, Muhammad Waqar; Zeshan, Furkh

2015-01-01

The composite service design modeling is an essential process of the service-oriented software development life cycle, where the candidate services, composite services, operations and their dependencies are required to be identified and specified before their design. However, a systematic service-oriented design modeling method for composite services is still in its infancy as most of the existing approaches provide the modeling of atomic services only. For these reasons, a new method (ComSDM) is proposed in this work for modeling the concept of service-oriented design to increase the reusability and decrease the complexity of system while keeping the service composition considerations in mind. Furthermore, the ComSDM method provides the mathematical representation of the components of service-oriented design using the graph-based theoryto facilitate the design quality measurement. To demonstrate that the ComSDM method is also suitable for composite service design modeling of distributed embedded real-time systems along with enterprise software development, it is implemented in the case study of a smart home. The results of the case study not only check the applicability of ComSDM, but can also be used to validate the complexity and reusability of ComSDM. This also guides the future research towards the design quality measurement such as using the ComSDM method to measure the quality of composite service design in service-oriented software system. PMID:25928358

Maintenance of a Minimum Spanning Forest in a Dynamic Planar Graph

DTIC Science & Technology

1990-01-18

v): Delete the edge from v to its parent , thereby dividing the tree containing v into two trees. evert(v): Make v the root of its tree by reversing...the path from v to the original root. find parent (v): Return the parent of v, or null if v is the root of its tree. find Ica(u, v): Return the least...given node (including the parent edge). The ordered set of edges adjacent to node v is called the edge list for v. For example, in our application we

A new user-friendly visual environment for breast MRI data analysis.

PubMed

Antonios, Danelakis; Dimitrios, Verganelakis A; Theoharis, Theoharis

2013-06-01

In this paper a novel, user friendly visual environment for Breast MRI Data Analysis is presented (BreDAn). Given planar MRI images before and after IV contrast medium injection, BreDAn generates kinematic graphs, color maps of signal increase and decrease and finally detects high risk breast areas. The advantage of BreDAn, which has been validated and tested successfully, is the automation of the radiodiagnostic process in an accurate and reliable manner. It can potentially facilitate radiologists' workload. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Continuous system modeling

NASA Technical Reports Server (NTRS)

Cellier, Francois E.

1991-01-01

A comprehensive and systematic introduction is presented for the concepts associated with 'modeling', involving the transition from a physical system down to an abstract description of that system in the form of a set of differential and/or difference equations, and basing its treatment of modeling on the mathematics of dynamical systems. Attention is given to the principles of passive electrical circuit modeling, planar mechanical systems modeling, hierarchical modular modeling of continuous systems, and bond-graph modeling. Also discussed are modeling in equilibrium thermodynamics, population dynamics, and system dynamics, inductive reasoning, artificial neural networks, and automated model synthesis.

Orientational analysis of planar fibre systems observed as a Poisson shot-noise process.

PubMed

Kärkkäinen, Salme; Lantuéjoul, Christian

2007-10-01

We consider two-dimensional fibrous materials observed as a digital greyscale image. The problem addressed is to estimate the orientation distribution of unobservable thin fibres from a greyscale image modelled by a planar Poisson shot-noise process. The classical stereological approach is not straightforward, because the point intensities of thin fibres along sampling lines may not be observable. For such cases, Kärkkäinen et al. (2001) suggested the use of scaled variograms determined from grey values along sampling lines in several directions. Their method is based on the assumption that the proportion between the scaled variograms and point intensities in all directions of sampling lines is constant. This assumption is proved to be valid asymptotically for Boolean models and dead leaves models, under some regularity conditions. In this work, we derive the scaled variogram and its approximations for a planar Poisson shot-noise process using the modified Bessel function. In the case of reasonable high resolution of the observed image, the scaled variogram has an approximate functional relation to the point intensity, and in the case of high resolution the relation is proportional. As the obtained relations are approximative, they are tested on simulations. The existing orientation analysis method based on the proportional relation is further experimented on images with different resolutions. The new result, the asymptotic proportionality between the scaled variograms and the point intensities for a Poisson shot-noise process, completes the earlier results for the Boolean models and for the dead leaves models.

Rapid assessment of mid-infrared refractive index anisotropy using a prism coupler: chemical vapor deposited ZnS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, Hong; Lipschultz, Kristen A.; Anheier, Norman C.

2012-04-01

A state-of-the-art mid-infrared prism coupler was used to study the refractive index properties of forward-looking-infrared (FLIR) grade zinc sulfide samples prepared with unique planar grain orientations and locations with respect to the CVD growth axis. This study was motivated by prior photoluminescence and x-ray diffraction measurements that suggested refractive index may vary according to grain orientation. Measurements were conducted to provide optical dispersion and thermal index (dn/dT) data at discrete laser wavelengths between 0.633 and 10.591 {mu}m at two temperature set points (30 C and 90 C). Refractive index measurements between samples exhibited an average standard deviation comparable to themore » uncertainty of the prism coupler measurement (0.0004 refractive index units), suggesting that the variation in refractive index as a function of planar grain orientation and CVD deposition time is negligible, and should have no impact on subsequent optical designs. Measured dispersion data at mid-infrared wavelengths was found to agree well with prior published measurements.« less

Planar cell polarity: one or two pathways?

PubMed Central

Lawrence, Peter A; Struhl, Gary; Casal, José

2009-01-01

In multicellular organisms, cells are polarised in the plane of the epithelial sheet, demonstrated in some cell types by oriented hairs or cilia. Many of the genes involved have been identified in Drosophila and are conserved in vertebrates. Here we dissect the logic of planar cell polarity (PCP). We review studies of genetic mosaics in adult flies. Marked cells of different genotypes are confronted, the aim being to understand how polarising information is generated and how it passes from one cell to another. We argue that the prevailing opinion that planar polarity depends on a single genetic pathway is wrong and conclude there are (at least) two independently acting processes. This conclusion has major consequences for the PCP field. PMID:17563758

Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing

PubMed Central

Ranjkesh, Amid; Park, Min-Kyu; Park, Do Hyuk; Park, Ji-Sub; Choi, Jun-Chan; Kim, Sung-Hoon; Kim, Hak-Rin

2015-01-01

We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation. PMID:26729116

Limited urban growth: London's street network dynamics since the 18th century.

PubMed

Masucci, A Paolo; Stanilov, Kiril; Batty, Michael

2013-01-01

We investigate the growth dynamics of Greater London defined by the administrative boundary of the Greater London Authority, based on the evolution of its street network during the last two centuries. This is done by employing a unique dataset, consisting of the planar graph representation of nine time slices of Greater London's road network spanning 224 years, from 1786 to 2010. Within this time-frame, we address the concept of the metropolitan area or city in physical terms, in that urban evolution reveals observable transitions in the distribution of relevant geometrical properties. Given that London has a hard boundary enforced by its long standing green belt, we show that its street network dynamics can be described as a fractal space-filling phenomena up to a capacitated limit, whence its growth can be predicted with a striking level of accuracy. This observation is confirmed by the analytical calculation of key topological properties of the planar graph, such as the topological growth of the network and its average connectivity. This study thus represents an example of a strong violation of Gibrat's law. In particular, we are able to show analytically how London evolves from a more loop-like structure, typical of planned cities, toward a more tree-like structure, typical of self-organized cities. These observations are relevant to the discourse on sustainable urban planning with respect to the control of urban sprawl in many large cities which have developed under the conditions of spatial constraints imposed by green belts and hard urban boundaries.

Thick crystalline films on foreign substrates

DOEpatents

Smith, Henry I.; Atwater, Harry A.; Geis, Michael W.

1986-01-01

To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 .mu.m) film on a foreign substrate, the film is formed so as to be thin (<1 .mu.m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns.

Thick crystalline films on foreign substrates

DOEpatents

Smith, H.I.; Atwater, H.A.; Geis, M.W.

1986-03-18

To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 [mu]m) film on a foreign substrate, the film is formed so as to be thin (<1 [mu]m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns. 2 figs.

Dynamic extension of the Simulation Problem Analysis Kernel (SPANK)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sowell, E.F.; Buhl, W.F.

1988-07-15

The Simulation Problem Analysis Kernel (SPANK) is an object-oriented simulation environment for general simulation purposes. Among its unique features is use of the directed graph as the primary data structure, rather than the matrix. This allows straightforward use of graph algorithms for matching variables and equations, and reducing the problem graph for efficient numerical solution. The original prototype implementation demonstrated the principles for systems of algebraic equations, allowing simulation of steady-state, nonlinear systems (Sowell 1986). This paper describes how the same principles can be extended to include dynamic objects, allowing simulation of general dynamic systems. The theory is developed andmore » an implementation is described. An example is taken from the field of building energy system simulation. 2 refs., 9 figs.« less

Maximum entropy analysis of NMR data of flexible multirotor molecules partially oriented in nematic solution: 2,2':5',2″-terthiophene, 2,2'- and 3,3'-dithiophene

NASA Astrophysics Data System (ADS)

Caldarelli, Stefano; Catalano, Donata; Di Bari, Lorenzo; Lumetti, Marco; Ciofalo, Maurizio; Alberto Veracini, Carlo

1994-07-01

The dipolar couplings observed by NMR spectroscopy of solutes in nematic solvents (LX-NMR) are used to build up the maximum entropy (ME) probability distribution function of the variables describing the orientational and internal motion of the molecule. The ME conformational distributions of 2,2'- and 3,3'-dithiophene and 2,2':5',2″-terthiophene (α-terthienyl)thus obtained are compared with the results of previous studies. The 2,2'- and 3,3'-dithiophene molecules exhibit equilibria among cisoid and transoid forms; the probability maxima correspond to planar and twisted conformers for 2,2'- or 3,3'-dithiophene, respectively, 2,2':5',2″-Terthiophene has two internal degrees of freedom; the ME approach indicates that the trans, trans and cis, trans planar conformations are the most probable. The correlation between the two intramolecular rotations is also discussed.

Instructional Review: An Introduction to Optical Methods for Characterizing Liquid Crystals at Interfaces

PubMed Central

Miller, Daniel S.; Carlton, Rebecca J.; Mushenheim, Peter C.; Abbott, Nicholas L.

2013-01-01

This Instructional Review describes methods and underlying principles that can be used to characterize both the orientations assumed spontaneously by liquid crystals (LCs) at interfaces and the strength with which the LCs are held in those orientations (so-called anchoring energies). The application of these methods to several different classes of LC interfaces is described, including solid and aqueous interfaces as well as planar and non-planar interfaces (such as those that define a LC-in-water emulsion droplet). These methods, which enable fundamental studies of the ordering of LCs at polymeric, chemically-functionalized and biomolecular interfaces, are described in this article at a level that can be easily understood by a non-expert reader such as an undergraduate or graduate student. We focus on optical methods because they are based on instrumentation that is found widely in research and teaching laboratories. PMID:23347378

Real time coarse orientation detection in MR scans using multi-planar deep convolutional neural networks

NASA Astrophysics Data System (ADS)

Bhatia, Parmeet S.; Reda, Fitsum; Harder, Martin; Zhan, Yiqiang; Zhou, Xiang Sean

2017-02-01

Automatically detecting anatomy orientation is an important task in medical image analysis. Specifically, the ability to automatically detect coarse orientation of structures is useful to minimize the effort of fine/accurate orientation detection algorithms, to initialize non-rigid deformable registration algorithms or to align models to target structures in model-based segmentation algorithms. In this work, we present a deep convolution neural network (DCNN)-based method for fast and robust detection of the coarse structure orientation, i.e., the hemi-sphere where the principal axis of a structure lies. That is, our algorithm predicts whether the principal orientation of a structure is in the northern hemisphere or southern hemisphere, which we will refer to as UP and DOWN, respectively, in the remainder of this manuscript. The only assumption of our method is that the entire structure is located within the scan's field-of-view (FOV). To efficiently solve the problem in 3D space, we formulated it as a multi-planar 2D deep learning problem. In the training stage, a large number coronal-sagittal slice pairs are constructed as 2-channel images to train a DCNN to classify whether a scan is UP or DOWN. During testing, we randomly sample a small number of coronal-sagittal 2-channel images and pass them through our trained network. Finally, coarse structure orientation is determined using majority voting. We tested our method on 114 Elbow MR Scans. Experimental results suggest that only five 2-channel images are sufficient to achieve a high success rate of 97.39%. Our method is also extremely fast and takes approximately 50 milliseconds per 3D MR scan. Our method is insensitive to the location of the structure in the FOV.

Dynamic analysis of four bar planar mechanism extended to six-bar planar mechanism with variable topology

NASA Astrophysics Data System (ADS)

Belleri, Basayya K.; Kerur, Shravankumar B.

2018-04-01

A computer-oriented procedure for solving the dynamic force analysis problem for general planar mechanisms is presented. This paper provides position analysis, velocity analysis, acceleration analysis and force analysis of six bar mechanism with variable topology approach. Six bar mechanism is constructed by joining two simple four bar mechanisms. Initially the position, velocity and acceleration analysis of first four bar mechanism are determined by using the input parameters. The outputs (angular displacement, velocity and acceleration of rocker)of first four bar mechanism are used as input parameter for the second four bar mechanism and the position, velocity, acceleration and forces are analyzed. With out-put parameters of second four-bar mechanism the force analysis of first four-bar mechanism is carried out.

Graph-based layout analysis for PDF documents

NASA Astrophysics Data System (ADS)

Xu, Canhui; Tang, Zhi; Tao, Xin; Li, Yun; Shi, Cao

2013-03-01

To increase the flexibility and enrich the reading experience of e-book on small portable screens, a graph based method is proposed to perform layout analysis on Portable Document Format (PDF) documents. Digital born document has its inherent advantages like representing texts and fractional images in explicit form, which can be straightforwardly exploited. To integrate traditional image-based document analysis and the inherent meta-data provided by PDF parser, the page primitives including text, image and path elements are processed to produce text and non text layer for respective analysis. Graph-based method is developed in superpixel representation level, and page text elements corresponding to vertices are used to construct an undirected graph. Euclidean distance between adjacent vertices is applied in a top-down manner to cut the graph tree formed by Kruskal's algorithm. And edge orientation is then used in a bottom-up manner to extract text lines from each sub tree. On the other hand, non-textual objects are segmented by connected component analysis. For each segmented text and non-text composite, a 13-dimensional feature vector is extracted for labelling purpose. The experimental results on selected pages from PDF books are presented.

Quasicharacteristic radiation of relativistic electrons at orientation motion in lithium halides crystals along charged planes and axes

NASA Astrophysics Data System (ADS)

Maksyuta, N. V.; Vysotskii, V. I.; Efimenko, S. V.

2016-07-01

The paper deals with the investigation of the orientation motion of relativistic electrons in charged (111) planes and charged [110] axes of lithium halides ionic crystals of LiF, LiCl, LiBr and LiI. On the basis of these investigations the spectra of quasicharacteristic radiation for the electron beams with various Lorentz-factors both in planar and axial cases have been calculated numerically.

Deforestation of Peano continua and minimal deformation retracts☆

PubMed Central

Conner, G.; Meilstrup, M.

2012-01-01

Every Peano continuum has a strong deformation retract to a deforested continuum, that is, one with no strongly contractible subsets attached at a single point. In a deforested continuum, each point with a one-dimensional neighborhood is either fixed by every self-homotopy of the space, or has a neighborhood which is a locally finite graph. A minimal deformation retract of a continuum (if it exists) is called its core. Every one-dimensional Peano continuum has a unique core, which can be obtained by deforestation. We give examples of planar Peano continua that contain no core but are deforested. PMID:23471120

Mechanical Strain Determines Cilia Length, Motility, and Planar Position in the Left-Right Organizer.

PubMed

Chien, Yuan-Hung; Srinivasan, Shyam; Keller, Ray; Kintner, Chris

2018-05-07

The Xenopus left-right organizer (LRO) breaks symmetry along the left-right axis of the early embryo by producing and sensing directed ciliary flow as a patterning cue. To carry out this process, the LRO contains different ciliated cell types that vary in cilia length, whether they are motile or sensory, and how they position their cilia along the anterior-posterior (A-P) planar axis. Here, we show that these different cilia features are specified in the prospective LRO during gastrulation, based on anisotropic mechanical strain that is oriented along the A-P axis, and graded in levels along the medial-lateral axis. Strain instructs ciliated cell differentiation by acting on a mesodermal prepattern present at blastula stages, involving foxj1. We propose that differential strain is a graded, developmental cue, linking the establishment of an A-P planar axis to cilia length, motility, and planar location during formation of the Xenopus LRO. Copyright © 2018 Elsevier Inc. All rights reserved.

CH₃NH₃PbI₃-based planar solar cells with magnetron-sputtered nickel oxide.

PubMed

Cui, Jin; Meng, Fanping; Zhang, Hua; Cao, Kun; Yuan, Huailiang; Cheng, Yibing; Huang, Feng; Wang, Mingkui

2014-12-24

Herein we report an investigation of a CH3NH3PbI3 planar solar cell, showing significant power conversion efficiency (PCE) improvement from 4.88% to 6.13% by introducing a homogeneous and uniform NiO blocking interlayer fabricated with the reactive magnetron sputtering method. The sputtered NiO layer exhibits enhanced crystallization, high transmittance, and uniform surface morphology as well as a preferred in-plane orientation of the (200) plane. The PCE of the sputtered-NiO-based perovskite p-i-n planar solar cell can be further promoted to 9.83% when a homogeneous and dense perovskite layer is formed with solvent-engineering technology, showing an impressive open circuit voltage of 1.10 V. This is about 33% higher than that of devices using the conventional spray pyrolysis of NiO onto a transparent conducting glass. These results highlight the importance of a morphology- and crystallization-compatible interlayer toward a high-performance inverted perovskite planar solar cell.

Grating tuned unstable resonator laser cavity

DOEpatents

Johnson, Larry C.

1982-01-01

An unstable resonator to be used in high power, narrow line CO.sub.2 pump lasers comprises an array of four reflectors in a ring configuration wherein spherical and planar wavefronts are separated from each other along separate optical paths and only the planar wavefronts are impinged on a plane grating for line tuning. The reflector array comprises a concave mirror for reflecting incident spherical waves as plane waves along an output axis to form an output beam. A plane grating on the output axis is oriented to reflect a portion of the output beam off axis onto a planar relay mirror spaced apart from the output axis in proximity to the concave mirror. The relay mirror reflects plane waves from the grating to impinge on a convex expanding mirror spaced apart from the output axis in proximity to the grating. The expanding mirror reflects the incident planar waves as spherical waves to illuminate the concave mirror. Tuning is provided by rotating the plane grating about an axis normal to the output axis.

Integral Equation Study of Molecular Fluids and Liquid Crystals in Two Dimensions

NASA Astrophysics Data System (ADS)

Ward, David Atlee

The Ornstein-Zernike (OZ) equation is solved with a Percus-Yevick (PY) closure for the hard ellipse and hard planar dumbell fluids in two dimensions. The correlation functions, including the orientation correlation function, are expanded in a set of orthogonal functions and the coefficients are solved for using an iterative algorithm developed by Lado. The pressure, compressibility, and orientation coefficients are computed for a variety of densities and molecular elongations. The hard planar dumbell fluid shows no orientational ordering. The PY values for the pressure differ from the corresponding Monte Carlo (MC) values by as much as 8% for the cases studied. The hard ellipse fluid exhibits some orientational ordering. Ordering is much more pronounced for ellipses with an axis ratio larger than 2.0. Pressure values computed for the hard ellipse fluid from the PY theory differ from the corresponding MC values by as much as 11% for the cases studied. As the PY solutions do exhibit a nematic character in the hard ellipse fluid, we find it to be a viable reference system for further studies of the nematic liquid crystal phase, though the isotropic-nematic (I-N) phase transition found by Vieillard-Baron was not observed in the PY solutions. The Maier-Saupe theory was reformulated based on the density functional formalism of Sluckin and Shukla. Using PY data of the hard ellipse as input for the direct correlation function in the isotropic phase, the orientational distribution was calculated. The values obtained showed only extremely weak nematic behavior.

Visualization of Documents and Concepts in Neuroinformatics with the 3D-SE Viewer

PubMed Central

Naud, Antoine; Usui, Shiro; Ueda, Naonori; Taniguchi, Tatsuki

2007-01-01

A new interactive visualization tool is proposed for mining text data from various fields of neuroscience. Applications to several text datasets are presented to demonstrate the capability of the proposed interactive tool to visualize complex relationships between pairs of lexical entities (with some semantic contents) such as terms, keywords, posters, or papers' abstracts. Implemented as a Java applet, this tool is based on the spherical embedding (SE) algorithm, which was designed for the visualization of bipartite graphs. Items such as words and documents are linked on the basis of occurrence relationships, which can be represented in a bipartite graph. These items are visualized by embedding the vertices of the bipartite graph on spheres in a three-dimensional (3-D) space. The main advantage of the proposed visualization tool is that 3-D layouts can convey more information than planar or linear displays of items or graphs. Different kinds of information extracted from texts, such as keywords, indexing terms, or topics are visualized, allowing interactive browsing of various fields of research featured by keywords, topics, or research teams. A typical use of the 3D-SE viewer is quick browsing of topics displayed on a sphere, then selecting one or several item(s) displays links to related terms on another sphere representing, e.g., documents or abstracts, and provides direct online access to the document source in a database, such as the Visiome Platform or the SfN Annual Meeting. Developed as a Java applet, it operates as a tool on top of existing resources. PMID:18974802

Visualization of Documents and Concepts in Neuroinformatics with the 3D-SE Viewer.

PubMed

Naud, Antoine; Usui, Shiro; Ueda, Naonori; Taniguchi, Tatsuki

2007-01-01

A new interactive visualization tool is proposed for mining text data from various fields of neuroscience. Applications to several text datasets are presented to demonstrate the capability of the proposed interactive tool to visualize complex relationships between pairs of lexical entities (with some semantic contents) such as terms, keywords, posters, or papers' abstracts. Implemented as a Java applet, this tool is based on the spherical embedding (SE) algorithm, which was designed for the visualization of bipartite graphs. Items such as words and documents are linked on the basis of occurrence relationships, which can be represented in a bipartite graph. These items are visualized by embedding the vertices of the bipartite graph on spheres in a three-dimensional (3-D) space. The main advantage of the proposed visualization tool is that 3-D layouts can convey more information than planar or linear displays of items or graphs. Different kinds of information extracted from texts, such as keywords, indexing terms, or topics are visualized, allowing interactive browsing of various fields of research featured by keywords, topics, or research teams. A typical use of the 3D-SE viewer is quick browsing of topics displayed on a sphere, then selecting one or several item(s) displays links to related terms on another sphere representing, e.g., documents or abstracts, and provides direct online access to the document source in a database, such as the Visiome Platform or the SfN Annual Meeting. Developed as a Java applet, it operates as a tool on top of existing resources.

Stacked thin layers of metaphase chromatin explain the geometry of chromosome rearrangements and banding.

PubMed

Daban, Joan-Ramon

2015-10-08

The three-dimensional organization of tightly condensed chromatin within metaphase chromosomes has been one of the most challenging problems in structural biology since the discovery of the nucleosome. This study shows that chromosome images obtained from typical banded karyotypes and from different multicolour cytogenetic analyses can be used to gain information about the internal structure of chromosomes. Chromatin bands and the connection surfaces in sister chromatid exchanges and in cancer translocations are planar and orthogonal to the chromosome axis. Chromosome stretching produces band splitting and even the thinnest bands are orthogonal and well defined, indicating that short stretches of DNA can occupy completely the chromosome cross-section. These observations impose strong physical constraints on models that attempt to explain chromatin folding in chromosomes. The thin-plate model, which consists of many stacked layers of planar chromatin perpendicular to the chromosome axis, is compatible with the observed orientation of bands, with the existence of thin bands, and with band splitting; it is also compatible with the orthogonal orientation and planar geometry of the connection surfaces in chromosome rearrangements. The results obtained provide a consistent interpretation of the chromosome structural properties that are used in clinical cytogenetics for the diagnosis of hereditary diseases and cancers.

Planar covariance of upper and lower limb elevation angles during hand-foot crawling in healthy young adults.

PubMed

MacLellan, M J; Catavitello, G; Ivanenko, Y P; Lacquaniti, F

2017-11-01

Habitual quadrupeds have been shown to display a planar covariance of segment elevation angle waveforms in the fore and hind limbs during many forms of locomotion. The purpose of the current study was to determine if humans generate similar patterns in the upper and lower limbs during hand-foot crawling. Nine healthy young adults performed hand-foot crawling on a treadmill at speeds of 1, 2, and 3 km/h. A principal component analysis (PCA) was applied to the segment elevation angle waveforms for the upper (upper arm, lower arm, and hand) and lower (thigh, shank, and foot) limbs separately. The planarity of the elevation angle waveforms was determined using the sum of the variance explained by the first two PCs and the orientation of the covariance plane was quantified using the direction cosines of the eigenvector orthogonal to the plane, projected upon each of the segmental semi-axes. Results showed that planarity of segment elevation angles was maintained in the upper and lower limbs (explained variance >97%), although a slight decrease was present in the upper limb when crawling at 3 km/h. The orientation of the covariance plane was highly limb-specific, consistent with animal studies and possibly related to the functional neural control differences between the upper and lower limbs. These results may suggest that the motor patterns stored in the central nervous system for quadrupedal locomotion may be retained through evolution and may still be exploited when humans perform such tasks.

A Graph Analytic Metric for Mitigating Advanced Persistent Threat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, John R.; Hogan, Emilie A.

2013-06-04

This paper introduces a novel graph analytic metric that can be used to measure the potential vulnerability of a cyber network to specific types of attacks that use lateral movement and privilege escalation such as the well known Pass The Hash, (PTH). The metric is computed from an oriented subgraph of the underlying cyber network induced by selecting only those edges for which a given property holds between the two vertices of the edge. The metric with respect to a select node on the subgraph is defined as the likelihood that the select node is reachable from another arbitrary nodemore » in the graph. This metric can be calculated dynamically from the authorization and auditing layers during the network security authorization phase and will potentially enable predictive deterrence against attacks such as PTH.« less

Airway epithelial homeostasis and planar cell polarity signaling depend on multiciliated cell differentiation.

PubMed

Vladar, Eszter K; Nayak, Jayakar V; Milla, Carlos E; Axelrod, Jeffrey D

2016-08-18

Motile airway cilia that propel contaminants out of the lung are oriented in a common direction by planar cell polarity (PCP) signaling, which localizes PCP protein complexes to opposite cell sides throughout the epithelium to orient cytoskeletal remodeling. In airway epithelia, PCP is determined in a 2-phase process. First, cell-cell communication via PCP complexes polarizes all cells with respect to the proximal-distal tissue axis. Second, during ciliogenesis, multiciliated cells (MCCs) undergo cytoskeletal remodeling to orient their cilia in the proximal direction. The second phase not only directs cilium polarization, but also consolidates polarization across the epithelium. Here, we demonstrate that in airway epithelia, PCP depends on MCC differentiation. PCP mutant epithelia have misaligned cilia, and also display defective barrier function and regeneration, indicating that PCP regulates multiple aspects of airway epithelial homeostasis. In humans, MCCs are often sparse in chronic inflammatory diseases, and these airways exhibit PCP dysfunction. The presence of insufficient MCCs impairs mucociliary clearance in part by disrupting PCP-driven polarization of the epithelium. Consistent with defective PCP, barrier function and regeneration are also disrupted. Pharmacological stimulation of MCC differentiation restores PCP and reverses these defects, suggesting its potential for broad therapeutic benefit in chronic inflammatory disease.

Ordering transitions of weakly anisotropic hard rods in narrow slitlike pores.

PubMed

Aliabadi, Roohollah; Gurin, Péter; Velasco, Enrique; Varga, Szabolcs

2018-01-01

The effect of strong confinement on the positional and orientational ordering is examined in a system of hard rectangular rods with length L and diameter D (L>D) using the Parsons-Lee modification of the second virial density-functional theory. The rods are nonmesogenic (L/D<3) and confined between two parallel hard walls, where the width of the pore (H) is chosen in such a way that both planar (particle's long axis parallel to the walls) and homeotropic (particle's long axis perpendicular to the walls) orderings are possible and a maximum of two layers is allowed to form in the pore. In the extreme confinement limit of H≤2D, where only one-layer structures appear, we observe a structural transition from a planar to a homeotropic fluid layer with increasing density, which becomes sharper as L→H. In wider pores (2D

A graph-based approach to detect spatiotemporal dynamics in satellite image time series

NASA Astrophysics Data System (ADS)

Guttler, Fabio; Ienco, Dino; Nin, Jordi; Teisseire, Maguelonne; Poncelet, Pascal

2017-08-01

Enhancing the frequency of satellite acquisitions represents a key issue for Earth Observation community nowadays. Repeated observations are crucial for monitoring purposes, particularly when intra-annual process should be taken into account. Time series of images constitute a valuable source of information in these cases. The goal of this paper is to propose a new methodological framework to automatically detect and extract spatiotemporal information from satellite image time series (SITS). Existing methods dealing with such kind of data are usually classification-oriented and cannot provide information about evolutions and temporal behaviors. In this paper we propose a graph-based strategy that combines object-based image analysis (OBIA) with data mining techniques. Image objects computed at each individual timestamp are connected across the time series and generates a set of evolution graphs. Each evolution graph is associated to a particular area within the study site and stores information about its temporal evolution. Such information can be deeply explored at the evolution graph scale or used to compare the graphs and supply a general picture at the study site scale. We validated our framework on two study sites located in the South of France and involving different types of natural, semi-natural and agricultural areas. The results obtained from a Landsat SITS support the quality of the methodological approach and illustrate how the framework can be employed to extract and characterize spatiotemporal dynamics.

Generalized topology for resonators having N commensurate harmonics

NASA Astrophysics Data System (ADS)

Danzi, Francesco; Gibert, James M.; Frulla, Giacomo; Cestino, Enrico

2018-04-01

Despite the ubiquity of both linear and nonlinear multimember resonators in MEMS and kinetic energy harvesting devices very few research efforts examine the orientation of members in the resonator on its dynamic behavior. Previous efforts to design this type of resonator constrains the members to have relative orientations that are 0○ or 90○ to each other, i.e., the elements are connected inline with adjoining members or are perpendicular to adjoining members. The work expands upon the existing body of research by considering the effect of the relative orientation between members on the dynamic behavior of the system. In this manuscript, we derive a generalized reduced-order model for the design of a multi-member planar resonator that has integer multiple modal frequencies. The model is based on a Rayleigh Ritz approximation where the number of degrees of freedom equals the number of structural members in the resonator. The analysis allows the generation of design curves, representing all the possible solutions for modal frequencies that are commensurate. The generalized model, valid for an N-DOF structure, is then restricted for a 2- and 3-DOF system/member resonator, where the linear dynamic behavior of the resonator is investigated in depth. Furthermore, this analysis demonstrates a rule of thumb; relaxing restrictions on the relative orientation of members in a planar structure, allows the structure to exhibit exactly N commensurable frequencies if it contains N members.

Orientational Dynamics of a Functionalized Alkyl Planar Monolayer Probed by Polarization-Selective Angle-Resolved Infrared Pump-Probe Spectroscopy.

PubMed

Nishida, Jun; Yan, Chang; Fayer, Michael D

2016-10-12

Polarization-selective angle-resolved infrared pump-probe spectroscopy was developed and used to study the orientational dynamics of a planar alkylsiloxane monolayer functionalized with a rhenium metal carbonyl headgroup on an SiO 2 surface. The technique, together with a time-averaged infrared linear dichroism measurement, characterized picosecond orientational relaxation of the headgroup occurring at the monolayer-air interface by employing several sets of incident angles of the infrared pulses relative to the sample surface. By application of this method and using a recently developed theory, it was possible to extract both the out-of-plane and "mainly"-in-plane orientational correlation functions in a model-independent manner. The observed correlation functions were compared with theoretically derived correlation functions based on several dynamical models. The out-of-plane correlation function reveals the highly restricted out-of-plane motions of the head groups and also suggests that the angular distribution of the transition dipole moments is bimodal. The mainly-in-plane correlation function, for the sample studied here with the strongly restricted out-of-plane motions, essentially arises from the purely in-plane dynamics. In contrast to the out-of-plane dynamics, significant in-plane motions occurring over various time scales were observed including an inertial motion, a restricted wobbling motion of ∼3 ps, and complete randomization occurring in ∼25 ps.

WKB solution 4×4 for electromagnetic waves in a planar magnetically anisotropic inhomogeneous layer

NASA Astrophysics Data System (ADS)

Moiseeva, Natalya Michailovna; Moiseev, Anton Vladimirovich

2018-04-01

In the paper, an oblique incidence of a plane electromagnetic wave on a planar magnetically anisotropic inhomogeneous layer is considered. We consider the case when all the components of the magnetic permeability tensor are non zero and vary with distance from the interface of media. The WKB method gives a matrix 4 × 4 solution for the projections of the electromagnetic wave fields during its propagation. The dependence of the cross-polarized components on the orientation of the anisotropic medium relative to the plane of incidence of the medium is analyzed.

Cup-Drawing Behavior of High-Strength Steel Sheets Containing Different Volume Fractions of Martensite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Shi-Hoon; Kim, Dae-Wan; Yang, Hoe-Seok

Planar anisotropy and cup-drawing behavior were investigated for high-strength steel sheets containing different volume fractions of martensite. Macrotexture analysis using XRD was conducted to capture the effect of crystallographic orientation on the planar anisotropy of high-strength steel sheets. A phenomenological yield function, Yld96, which accounts for the anisotropy of yield stress and r-values, was implemented into ABAQUS using the user subroutine UMAT. Cup drawing of high-strength steel sheets was simulated using the FEM code. The profiles of earing and thickness strain were compared with the experimentally measured results.

DOGMA: A Disk-Oriented Graph Matching Algorithm for RDF Databases

NASA Astrophysics Data System (ADS)

Bröcheler, Matthias; Pugliese, Andrea; Subrahmanian, V. S.

RDF is an increasingly important paradigm for the representation of information on the Web. As RDF databases increase in size to approach tens of millions of triples, and as sophisticated graph matching queries expressible in languages like SPARQL become increasingly important, scalability becomes an issue. To date, there is no graph-based indexing method for RDF data where the index was designed in a way that makes it disk-resident. There is therefore a growing need for indexes that can operate efficiently when the index itself resides on disk. In this paper, we first propose the DOGMA index for fast subgraph matching on disk and then develop a basic algorithm to answer queries over this index. This algorithm is then significantly sped up via an optimized algorithm that uses efficient (but correct) pruning strategies when combined with two different extensions of the index. We have implemented a preliminary system and tested it against four existing RDF database systems developed by others. Our experiments show that our algorithm performs very well compared to these systems, with orders of magnitude improvements for complex graph queries.

Background Oriented Schlieren Implementation in a Jet-Surface Interaction Test

NASA Technical Reports Server (NTRS)

Clem, Michelle M.; Brown, Clifford A.; Fagan, Amy

2013-01-01

Many current and future aircraft designs rely on the wing or other aircraft surfaces to shield the engine noise from observers on the ground. However the available data regarding how a planar surface interacts with a jet to shield and/or enhance the jet noise are currently limited. Therefore, the Jet-Surface Interaction Tests supported by NASA's Fundamental Aeronautics Program's Fixed Wing Project were undertaken to supply experimental data covering a wide range of surface geometries and positions interacting with high-speed jet flows in order to support the development of noise prediction methods. Phase 1 of the Test was conducted in the Aero-Acoustic Propulsion Laboratory at NASA Glenn Research Center and consisted of validating noise prediction schemes for a round nozzle interacting with a planar surface. Phased array data and far-field acoustic data were collected for both the shielded and reflected sides of the surface. Phase 1 results showed that the broadband shock noise was greatly reduced by the surface when the jet was operated at the over-expanded condition, however, it was unclear whether this reduction was due a change in the shock cell structure by the surface. In the present study, Background Oriented Schlieren is implemented in Phase 2 of the Jet-Surface Interaction Tests to investigate whether the planar surface interacts with the high-speed jet ow to change the shock cell structure. Background Oriented Schlieren data are acquired for under-expanded, ideally-expanded, and over-expanded ow regimes for multiple axial and radial positions of the surface at three different plate lengths. These data are analyzed with far-field noise measurements to relate the shock cell structure to the broadband shock noise produced by a jet near a surface.

Using genre pedagogy to promote student proficiency in the language required for interpreting line graphs

NASA Astrophysics Data System (ADS)

Smit, Jantien; Bakker, Arthur; van Eerde, Dolly; Kuijpers, Maggie

2016-09-01

The importance of language in mathematics learning has been widely acknowledged. However, little is known about how to make this insight productive in the design and enactment of language-oriented mathematics education. In a design-based research project, we explored how language-oriented mathematics education can be designed and enacted. We drew on genre pedagogy to promote student proficiency in the language required for interpreting line graphs. In the intervention, the teacher used scaffolding strategies to focus students' attention on the structure and linguistic features of the language involved in this particular domain. The research question addressed in this paper is how student proficiency in this language may be promoted. The study comprised nine lessons involving 22 students in grades 5 and 6 (aged 10-12); of these students, 19 had a migrant background. In light of the research aim, we first describe the rationale behind our design. Next, we illustrate how the design was enacted by means of a case study focusing on one student in the classroom practice of developing proficiency in the language required for interpreting line graphs. On the basis of pre- and posttest scores, we conclude that overall their proficiency has increased. Together, the results indicate that and how genre pedagogy may be used to help students become more proficient in the language required in a mathematical domain.

Automated method for identification and artery-venous classification of vessel trees in retinal vessel networks.

PubMed

Joshi, Vinayak S; Reinhardt, Joseph M; Garvin, Mona K; Abramoff, Michael D

2014-01-01

The separation of the retinal vessel network into distinct arterial and venous vessel trees is of high interest. We propose an automated method for identification and separation of retinal vessel trees in a retinal color image by converting a vessel segmentation image into a vessel segment map and identifying the individual vessel trees by graph search. Orientation, width, and intensity of each vessel segment are utilized to find the optimal graph of vessel segments. The separated vessel trees are labeled as primary vessel or branches. We utilize the separated vessel trees for arterial-venous (AV) classification, based on the color properties of the vessels in each tree graph. We applied our approach to a dataset of 50 fundus images from 50 subjects. The proposed method resulted in an accuracy of 91.44% correctly classified vessel pixels as either artery or vein. The accuracy of correctly classified major vessel segments was 96.42%.

Graph Representations of Flow and Transport in Fracture Networks using Machine Learning

NASA Astrophysics Data System (ADS)

Srinivasan, G.; Viswanathan, H. S.; Karra, S.; O'Malley, D.; Godinez, H. C.; Hagberg, A.; Osthus, D.; Mohd-Yusof, J.

2017-12-01

Flow and transport of fluids through fractured systems is governed by the properties and interactions at the micro-scale. Retaining information about the micro-structure such as fracture length, orientation, aperture and connectivity in mesh-based computational models results in solving for millions to billions of degrees of freedom and quickly renders the problem computationally intractable. Our approach depicts fracture networks graphically, by mapping fractures to nodes and intersections to edges, thereby greatly reducing computational burden. Additionally, we use machine learning techniques to build simulators on the graph representation, trained on data from the mesh-based high fidelity simulations to speed up computation by orders of magnitude. We demonstrate our methodology on ensembles of discrete fracture networks, dividing up the data into training and validation sets. Our machine learned graph-based solvers result in over 3 orders of magnitude speedup without any significant sacrifice in accuracy.

Fiber tracking of brain white matter based on graph theory.

PubMed

Lu, Meng

2015-01-01

Brain white matter tractography is reconstructed via diffusion-weighted magnetic resonance images. Due to the complex structure of brain white matter fiber bundles, fiber crossing and fiber branching are abundant in human brain. And regular methods with diffusion tensor imaging (DTI) can't accurately handle this problem. the biggest problems of the brain tractography. Therefore, this paper presented a novel brain white matter tractography method based on graph theory, so the fiber tracking between two voxels is transformed into locating the shortest path in a graph. Besides, the presented method uses Q-ball imaging (QBI) as the source data instead of DTI, because QBI can provide accurate information about multiple fiber crossing and branching in one voxel using orientation distribution function (ODF). Experiments showed that the presented method can accurately handle the problem of brain white matter fiber crossing and branching, and reconstruct brain tractograhpy both in phantom data and real brain data.

Brain white matter fiber estimation and tractography using Q-ball imaging and Bayesian MODEL.

PubMed

Lu, Meng

2015-01-01

Diffusion tensor imaging allows for the non-invasive in vivo mapping of the brain tractography. However, fiber bundles have complex structures such as fiber crossings, fiber branchings and fibers with large curvatures that tensor imaging (DTI) cannot accurately handle. This study presents a novel brain white matter tractography method using Q-ball imaging as the data source instead of DTI, because QBI can provide accurate information about multiple fiber crossings and branchings in a single voxel using an orientation distribution function (ODF). The presented method also uses graph theory to construct the Bayesian model-based graph, so that the fiber tracking between two voxels can be represented as the shortest path in a graph. Our experiment showed that our new method can accurately handle brain white matter fiber crossings and branchings, and reconstruct brain tractograhpy both in phantom data and real brain data.

Molecular aspect ratio and anchoring strength effects in a confined Gay-Berne liquid crystal

NASA Astrophysics Data System (ADS)

Cañeda-Guzmán, E.; Moreno-Razo, J. A.; Díaz-Herrera, E.; Sambriski, E. J.

2014-04-01

Phase diagrams for Gay-Berne (GB) fluids were obtained from molecular dynamics simulations for GB(2, 5, 1, 2) (i.e. short mesogens) and GB(3, 5, 1, 2) (i.e. long mesogens), which yield isotropic, nematic, and smectic-B phases. The long-mesogen fluid also yields the smectic-A phase. Ordered phases of the long-mesogen fluid form at higher temperatures and lower densities when compared to those of the short-mesogen fluid. The effect of confinement under weak and strong substrate couplings in slab geometry was investigated. Compared to the bulk, the isotropic-nematic transition does not shift in temprature significantly for the weakly coupled substrate in either mesogen fluid. However, the strongly coupled substrate shifts the transition to lower temperature. Confinement induces marked stratification in the short-mesogen fluid. This effect diminishes with distance from the substrate, yielding bulk-like behaviour in the slab central region. Fluid stratification is very weak for the long-mesogen fluid, but the strongly coupled substrate induces 'smectisation', an ordering effect that decays with distance. Orientation of the fluid on the substrate depends on the mesogen. There is no preferred orientation in a plane parallel to the substrate for the weakly coupled case. In the strongly coupled case, the mesogen orientation mimics that of adjacent fluid layers. Planar anchoring is observed with a broad distribution of orientations in the weakly coupled case. In the strongly coupled case, the distribution leans toward planar orientations for the short-mesogen fluid, while a marginal preference for tilting persists in the long-mesogen fluid.

Coordination of planar cell polarity pathways through Spiny-legs

PubMed Central

Ambegaonkar, Abhijit A; Irvine, Kenneth D

2015-01-01

Morphogenesis and physiology of tissues and organs requires planar cell polarity (PCP) systems that orient and coordinate cells and their behaviors, but the relationship between PCP systems has been controversial. We have characterized how the Frizzled and Dachsous-Fat PCP systems are connected through the Spiny-legs isoform of the Prickle-Spiny-legs locus. Two different components of the Dachsous-Fat system, Dachsous and Dachs, can each independently interact with Spiny-legs and direct its localization in vivo. Through characterization of the contributions of Prickle, Spiny-legs, Dachsous, Fat, and Dachs to PCP in the Drosophila wing, eye, and abdomen, we define where Dachs-Spiny-legs and Dachsous-Spiny-legs interactions contribute to PCP, and provide a new understanding of the orientation of polarity and the basis of PCP phenotypes. Our results support the direct linkage of PCP systems through Sple in specific locales, while emphasizing that cells can be subject to and must ultimately resolve distinct, competing PCP signals. DOI: http://dx.doi.org/10.7554/eLife.09946.001 PMID:26505959

Self-propulsion of a catalytically active particle near a planar wall: from reflection to sliding and hovering.

PubMed

Uspal, W E; Popescu, M N; Dietrich, S; Tasinkevych, M

2015-01-21

Micron-sized particles moving through a solution in response to self-generated chemical gradients serve as model systems for studying active matter. Their far-reaching potential applications will require the particles to sense and respond to their local environment in a robust manner. The self-generated hydrodynamic and chemical fields, which induce particle motion, probe and are modified by that very environment, including confining boundaries. Focusing on a catalytically active Janus particle as a paradigmatic example, we predict that near a hard planar wall such a particle exhibits several scenarios of motion: reflection from the wall, motion at a steady-state orientation and height above the wall, or motionless, steady "hovering." Concerning the steady states, the height and the orientation are determined both by the proportion of catalyst coverage and the interactions of the solutes with the different "faces" of the particle. Accordingly, we propose that a desired behavior can be selected by tuning these parameters via a judicious design of the particle surface chemistry.

Crack Growth Mechanisms under Anti-Plane Shear in Composite Laminates

NASA Astrophysics Data System (ADS)

Horner, Allison Lynne

The research conducted for this dissertation focuses on determining the mechanisms associated with crack growth in polymer matrix composite laminates subjected to anti-plane shear (mode III) loading. For mode III split-beam test methods were proposed, and initial evaluations were conducted. A single test method was selected for further evaluation. Using this test method, it was determined that the apparent mode III delamination toughness, GIIIc , depended on geometry, which indicated a true material property was not being measured. Transverse sectioning and optical microscopy revealed an array of transverse matrix cracks, or echelon cracks, oriented at approximately 45° and intersecting the plane of the delamination. Subsequent investigations found the echelon array formed prior to the onset of planar delamination advance and that growth of the planar delamination is always coupled to echelon array formation in these specimens. The evolution of the fracture surfaces formed by the echelon array and planar delamination were studied, and it was found that the development was similar to crack growth in homogenous materials subjected to mode III or mixed mode I-III loading, although the composite laminate architecture constrained the fracture surface development differently than homogenous materials. It was also found that, for split-beam specimens such as those used herein, applying an anti-plane shear load results in twisting of the specimen's uncracked region which gives rise to a mixed-mode I-III load condition. This twisting has been related to the apparent mode III toughness as well as the orientation of the transverse matrix cracks. A finite element model was then developed to study the mechanisms of initial echelon array formation. From this, it is shown that an echelon array will develop, but will become self-limiting prior to the onset of planar delamination growth.

Integrability of conformal fishnet theory

NASA Astrophysics Data System (ADS)

Gromov, Nikolay; Kazakov, Vladimir; Korchemsky, Gregory; Negro, Stefano; Sizov, Grigory

2018-01-01

We study integrability of fishnet-type Feynman graphs arising in planar four-dimensional bi-scalar chiral theory recently proposed in arXiv:1512.06704 as a special double scaling limit of gamma-deformed N = 4 SYM theory. We show that the transfer matrix "building" the fishnet graphs emerges from the R-matrix of non-compact conformal SU(2 , 2) Heisenberg spin chain with spins belonging to principal series representations of the four-dimensional conformal group. We demonstrate explicitly a relationship between this integrable spin chain and the Quantum Spectral Curve (QSC) of N = 4 SYM. Using QSC and spin chain methods, we construct Baxter equation for Q-functions of the conformal spin chain needed for computation of the anomalous dimensions of operators of the type tr( ϕ 1 J ) where ϕ 1 is one of the two scalars of the theory. For J = 3 we derive from QSC a quantization condition that fixes the relevant solution of Baxter equation. The scaling dimensions of the operators only receive contributions from wheel-like graphs. We develop integrability techniques to compute the divergent part of these graphs and use it to present the weak coupling expansion of dimensions to very high orders. Then we apply our exact equations to calculate the anomalous dimensions with J = 3 to practically unlimited precision at any coupling. These equations also describe an infinite tower of local conformal operators all carrying the same charge J = 3. The method should be applicable for any J and, in principle, to any local operators of bi-scalar theory. We show that at strong coupling the scaling dimensions can be derived from semiclassical quantization of finite gap solutions describing an integrable system of noncompact SU(2 , 2) spins. This bears similarities with the classical strings arising in the strongly coupled limit of N = 4 SYM.

Constructing financial network based on PMFG and threshold method

NASA Astrophysics Data System (ADS)

Nie, Chun-Xiao; Song, Fu-Tie

2018-04-01

Based on planar maximally filtered graph (PMFG) and threshold method, we introduced a correlation-based network named PMFG-based threshold network (PTN). We studied the community structure of PTN and applied ISOMAP algorithm to represent PTN in low-dimensional Euclidean space. The results show that the community corresponds well to the cluster in the Euclidean space. Further, we studied the dynamics of the community structure and constructed the normalized mutual information (NMI) matrix. Based on the real data in the market, we found that the volatility of the market can lead to dramatic changes in the community structure, and the structure is more stable during the financial crisis.

Regulation of planar growth by the Arabidopsis AGC protein kinase UNICORN.

PubMed

Enugutti, Balaji; Kirchhelle, Charlotte; Oelschner, Maxi; Torres Ruiz, Ramón Angel; Schliebner, Ivo; Leister, Dario; Schneitz, Kay

2012-09-11

The spatial coordination of growth is of central importance for the regulation of plant tissue architecture. Individual layers, such as the epidermis, are clonally propagated and structurally maintained by symmetric cell divisions that are oriented along the plane of the layer. The developmental control of this process is poorly understood. The simple cellular basis and sheet-like structure of Arabidopsis integuments make them an attractive model system to address planar growth. Here we report on the characterization of the Arabidopsis UNICORN (UCN) gene. Analysis of ucn integuments reveals localized distortion of planar growth, eventually resulting in an ectopic multicellular protrusion. In addition, ucn mutants exhibit ectopic growth in filaments and petals, as well as aberrant embryogenesis. We further show that UCN encodes an active AGC VIII kinase. Genetic, biochemical, and cell biological data suggest that UCN suppresses ectopic growth in integuments by directly repressing the KANADI transcription factor ABERRANT TESTA SHAPE. Our findings indicate that UCN represents a unique plant growth regulator that maintains planar growth of integuments by repressing a developmental regulator involved in the control of early integument growth and polarity.

Planar Covariation of Hindlimb and Forelimb Elevation Angles during Terrestrial and Aquatic Locomotion of Dogs

PubMed Central

Catavitello, Giovanna; Ivanenko, Yuri P.; Lacquaniti, Francesco

2015-01-01

The rich repertoire of locomotor behaviors in quadrupedal animals requires flexible inter-limb and inter-segmental coordination. Here we studied the kinematic coordination of different gaits (walk, trot, gallop, and swim) of six dogs (Canis lupus familiaris) and, in particular, the planar covariation of limb segment elevation angles. The results showed significant variations in the relative duration of rearward limb movement, amplitude of angular motion, and inter-limb coordination, with gait patterns ranging from a lateral sequence of footfalls during walking to a diagonal sequence in swimming. Despite these differences, the planar law of inter-segmental coordination was maintained across different gaits in both forelimbs and hindlimbs. Notably, phase relationships and orientation of the covariation plane were highly limb specific, consistent with the functional differences in their neural control. Factor analysis of published muscle activity data also demonstrated differences in the characteristic timing of basic activation patterns of the forelimbs and hindlimbs. Overall, the results demonstrate that the planar covariation of inter-segmental coordination has emerged for both fore- and hindlimbs and all gaits, although in a limb-specific manner. PMID:26218076

Equivalent Circuit of the Neuro-Electronic Junction for Signal Recordings From Planar and Engulfed Micro-Nano-Electrodes.

PubMed

Massobrio, Giuseppe; Martinoia, Sergio; Massobrio, Paolo

2018-02-01

In the latest years, several attempts to develop extracellular microtransducers to record electrophysiological activity of excitable cells have been done. In particular, many efforts have been oriented to increase the coupling conditions, and, thus, improving the quality of the recorded signal. Gold mushroom-shaped microelectrodes (GMμE) are an example of nano-devices to achieve those requirements. In this study, we developed an equivalent electrical circuit of the neuron-microelectrode system interface to simulate signal recordings from both planar and engulfed micro-nano-electrodes. To this purpose, models of the neuron, planar, gold planar microelectrode, and GMμE, neuro-electronic junction (microelectrode-electrolyte interface, cleft effect, and protein-glycocalyx electric double layer) are presented. Then, neuronal electrical activity is simulated by Hspice software, and analyzed as a function of the most sensitive biophysical models parameters, such as the neuron-microelectrode cleft width, spreading and seal resistances, ion-channel densities, double-layer properties, and microelectrode geometries. Results are referenced to the experimentally recorded electrophysiological neuronal signals reported in the literature.

Experimental and modelling study of the effect of airflow orientation with respect to strip electrode on ozone production of surface dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Mikeš, J.; Pekárek, S.; Soukup, I.

2016-11-01

This study examines the effect of airflow orientation with respect to the strip active electrode on concentration of ozone and nitrogen dioxide produced in a planar generator based on the surface dielectric barrier discharge. The orientation of the airflow was tested in parallel and perpendicular with respect to the strips. It was found that in the investigated range of average discharge power, the ozone concentration increases approximately by 25% when airflow was oriented in parallel with respect to the strips in comparison with perpendicular orientation of the airflow. Similarly the increase of nitrogen dioxide concentration was observed for parallel orientation of the airflow with respect to the strips in comparison with the perpendicular orientation of the airflow. Within the range of wavelengths from 250 to 1100 nm, the changes of intensities of spectral lines associated with airflow orientation have been observed. A 3D numerical model describing ion trajectories and airflow patterns have also been developed.

A Graph Oriented Approach for Network Forensic Analysis

ERIC Educational Resources Information Center

Wang, Wei

2010-01-01

Network forensic analysis is a process that analyzes intrusion evidence captured from networked environment to identify suspicious entities and stepwise actions in an attack scenario. Unfortunately, the overwhelming amount and low quality of output from security sensors make it difficult for analysts to obtain a succinct high-level view of complex…

Inferring Action Structure and Causal Relationships in Continuous Sequences of Human Action

DTIC Science & Technology

2014-01-01

language processing literature (e.g., Brent, 1999; Venkataraman , 2001), and which were also used by Goldwater et al. (2009). Precision (P) is the...trees in oriented linear graphs. Simon Stevin: Wis-en Natuurkundig Tijdschrift, 28 , 203. Venkataraman , A. (2001). A statistical model for word discovery

A Teacher's Journey with a New Generation Handheld: Decisions, Struggles, and Accomplishments

ERIC Educational Resources Information Center

Ozgun-Koca, S. Asli; Meagher, Michael; Edwards, Michael Todd

2011-01-01

In this technology-oriented age, teachers face daily decisions regarding the use of advanced digital technologies--graphing calculators, dynamic geometry software, blogs, wikis, podcasts and the like--to enhance student mathematical understanding in their classrooms. In this case study, the authors use the Technological, Pedagogical, and Content…

Planar maneuvering control of underwater snake robots using virtual holonomic constraints.

PubMed

Kohl, Anna M; Kelasidi, Eleni; Mohammadi, Alireza; Maggiore, Manfredi; Pettersen, Kristin Y

2016-11-24

This paper investigates the problem of planar maneuvering control for bio-inspired underwater snake robots that are exposed to unknown ocean currents. The control objective is to make a neutrally buoyant snake robot which is subject to hydrodynamic forces and ocean currents converge to a desired planar path and traverse the path with a desired velocity. The proposed feedback control strategy enforces virtual constraints which encode biologically inspired gaits on the snake robot configuration. The virtual constraints, parametrized by states of dynamic compensators, are used to regulate the orientation and forward speed of the snake robot. A two-state ocean current observer based on relative velocity sensors is proposed. It enables the robot to follow the path in the presence of unknown constant ocean currents. The efficacy of the proposed control algorithm for several biologically inspired gaits is verified both in simulations for different path geometries and in experiments.

Planar Cell Polarity Breaks the Symmetry of PAR Protein Distribution prior to Mitosis in Drosophila Sensory Organ Precursor Cells.

PubMed

Besson, Charlotte; Bernard, Fred; Corson, Francis; Rouault, Hervé; Reynaud, Elodie; Keder, Alyona; Mazouni, Khalil; Schweisguth, François

2015-04-20

During development, cell-fate diversity can result from the unequal segregation of fate determinants at mitosis. Polarization of the mother cell is essential for asymmetric cell division (ACD). It often involves the formation of a cortical domain containing the PAR complex proteins Par3, Par6, and atypical protein kinase C (aPKC). In the fly notum, sensory organ precursor cells (SOPs) divide asymmetrically within the plane of the epithelium and along the body axis to generate two distinct cells. Fate asymmetry depends on the asymmetric localization of the PAR complex. In the absence of planar cell polarity (PCP), SOPs divide with a random planar orientation but still asymmetrically, showing that PCP is dispensable for PAR asymmetry at mitosis. To study when and how the PAR complex localizes asymmetrically, we have used a quantitative imaging approach to measure the planar polarization of the proteins Bazooka (Baz, fly Par3), Par6, and aPKC in living pupae. By using imaging of functional GFP-tagged proteins with image processing and computational modeling, we find that Baz, Par6, and aPKC become planar polarized prior to mitosis in a manner independent of the AuroraA kinase and that PCP is required for the planar polarization of Baz, Par6, and aPKC during interphase. This indicates that a "mitosis rescue" mechanism establishes asymmetry at mitosis in PCP mutants. This study therefore identifies PCP as the initial symmetry-breaking signal for the planar polarization of PAR proteins in asymmetrically dividing SOPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

How Different EEG References Influence Sensor Level Functional Connectivity Graphs

PubMed Central

Huang, Yunzhi; Zhang, Junpeng; Cui, Yuan; Yang, Gang; He, Ling; Liu, Qi; Yin, Guangfu

2017-01-01

Highlights: Hamming Distance is applied to distinguish the difference of functional connectivity networkThe orientations of sources are testified to influence the scalp Functional Connectivity Graph (FCG) from different references significantlyREST, the reference electrode standardization technique, is proved to have an overall stable and excellent performance in variable situations. The choice of an electroencephalograph (EEG) reference is a practical issue for the study of brain functional connectivity. To study how EEG reference influence functional connectivity estimation (FCE), this study compares the differences of FCE resulting from the different references such as REST (the reference electrode standardization technique), average reference (AR), linked mastoids (LM), and left mastoid references (LR). Simulations involve two parts. One is based on 300 dipolar pairs, which are located on the superficial cortex with a radial source direction. The other part is based on 20 dipolar pairs. In each pair, the dipoles have various orientation combinations. The relative error (RE) and Hamming distance (HD) between functional connectivity matrices of ideal recordings and that of recordings obtained with different references, are metrics to compare the differences of the scalp functional connectivity graph (FCG) derived from those two kinds of recordings. Lower RE and HD values imply more similarity between the two FCGs. Using the ideal recording (IR) as a standard, the results show that AR, LM and LR perform well only in specific conditions, i.e., AR performs stable when there is no upward component in sources' orientation. LR achieves desirable results when the sources' locations are away from left ear. LM achieves an indistinct difference with IR, i.e., when the distribution of source locations is symmetric along the line linking the two ears. However, REST not only achieves excellent performance for superficial and radial dipolar sources, but also achieves a stable and robust performance with variable source locations and orientations. Benefitting from the stable and robust performance of REST vs. other reference methods, REST might best recover the real FCG of EEG. Thus, REST based FCG may be a good candidate to compare the FCG of EEG based on different references from different labs. PMID:28725175

Modelling NDE pulse-echo inspection of misorientated planar rough defects using an elastic finite element method

NASA Astrophysics Data System (ADS)

Pettit, J. R.; Walker, A. E.; Lowe, M. J. S.

2015-03-01

Pulse-echo ultrasonic NDE examination of large pressure vessel forgings is a design and construction code requirement in the power generation industry. Such inspections aim to size and characterise potential defects that may have formed during the forging process. Typically these defects have a range of orientations and surface roughnesses which can greatly affect ultrasonic wave scattering behaviour. Ultrasonic modelling techniques can provide insight into defect response and therefore aid in characterisation. However, analytical approaches to solving these scattering problems can become inaccurate, especially when applied to increasingly complex defect geometries. To overcome these limitations a elastic Finite Element (FE) method has been developed to simulate pulse-echo inspections of embedded planar defects. The FE model comprises a significantly reduced spatial domain allowing for a Monte-Carlo based approach to consider multiple realisations of defect orientation and surface roughness. The results confirm that defects aligned perpendicular to the path of beam propagation attenuate ultrasonic signals according to the level of surface roughness. However, for defects orientated away from this plane, surface roughness can increase the magnitude of the scattered component propagating back along the path of the incident beam. This study therefore highlights instances where defect roughness increases the magnitude of ultrasonic scattered signals, as opposed to attenuation which is more often assumed.

Airway epithelial homeostasis and planar cell polarity signaling depend on multiciliated cell differentiation

PubMed Central

Vladar, Eszter K.; Nayak, Jayakar V.; Milla, Carlos E.; Axelrod, Jeffrey D.

2016-01-01

Motile airway cilia that propel contaminants out of the lung are oriented in a common direction by planar cell polarity (PCP) signaling, which localizes PCP protein complexes to opposite cell sides throughout the epithelium to orient cytoskeletal remodeling. In airway epithelia, PCP is determined in a 2-phase process. First, cell-cell communication via PCP complexes polarizes all cells with respect to the proximal-distal tissue axis. Second, during ciliogenesis, multiciliated cells (MCCs) undergo cytoskeletal remodeling to orient their cilia in the proximal direction. The second phase not only directs cilium polarization, but also consolidates polarization across the epithelium. Here, we demonstrate that in airway epithelia, PCP depends on MCC differentiation. PCP mutant epithelia have misaligned cilia, and also display defective barrier function and regeneration, indicating that PCP regulates multiple aspects of airway epithelial homeostasis. In humans, MCCs are often sparse in chronic inflammatory diseases, and these airways exhibit PCP dysfunction. The presence of insufficient MCCs impairs mucociliary clearance in part by disrupting PCP-driven polarization of the epithelium. Consistent with defective PCP, barrier function and regeneration are also disrupted. Pharmacological stimulation of MCC differentiation restores PCP and reverses these defects, suggesting its potential for broad therapeutic benefit in chronic inflammatory disease. PMID:27570836

On the Magnitude and Orientation of Stress during Shock Metamorphism: Understanding Peak Ring Formation by Combining Observations and Models.

NASA Astrophysics Data System (ADS)

Rae, A.; Poelchau, M.; Collins, G. S.; Timms, N.; Cavosie, A. J.; Lofi, J.; Salge, T.; Riller, U. P.; Ferrière, L.; Grieve, R. A. F.; Osinski, G.; Morgan, J. V.; Expedition 364 Science Party, I. I.

2017-12-01

Shock metamorphism occurs during the earliest moments after impact. The magnitude and orientation of shock leaves recordable signatures in rocks, which spatially vary across an impact structure. Consequently, observations of shock metamorphism can be used to understand deformation and its history within a shock wave, and to examine subsequent deformation during crater modification. IODP-ICDP Expedition 364 recovered nearly 600 m of shocked target rocks from the peak ring of the Chicxulub Crater. Samples from the expedition were used to measure the magnitude and orientation of shock in peak ring materials, and to determine the mechanism of peak-ring emplacement. Here, we present the results of petrographic analyses of the shocked granitic target rocks of the Chicxulub peak ring; using universal-stage optical microscopy, back-scattered electron images, and electron back-scatter diffraction. Deformation microstructures in quartz include planar deformation features (PDFs), feather features (FFs), which are unique to shock conditions, as well as planar fractures and crystal-plastic deformation bands. The assemblage of PDFs in quartz suggest that the peak-ring rocks experienced shock pressures of 15 GPa throughout the recovered drill core, and that the orientation of FFs are consistent with the present-day orientation of the maximum principal stress direction during shock is close to vertical. Numerical impact simulations of the impact event were run to determine the magnitude and orientation of principal stresses during shock and track those orientations throughout crater formation. Our results are remarkably consistent with the geological data, and accurately predict both the shock-pressure magnitudes, and the final near-vertical orientation of the direction of maximum principal stress in the shock wave. Furthermore, analysis of the state of stress throughout the impact event can be used to constrain the timing of fracture and fault orientations observed in the core. Our results quantitatively describe the deviatoric stress conditions of rocks in shock, which are consistent with observations of shock deformation. Our integrated analysis provides further support for the dynamic collapse model of peak-ring formation, and places dynamic constraints on the conditions of peak-ring formation.

Classification of user interfaces for graph-based online analytical processing

NASA Astrophysics Data System (ADS)

Michaelis, James R.

2016-05-01

In the domain of business intelligence, user-oriented software for conducting multidimensional analysis via Online- Analytical Processing (OLAP) is now commonplace. In this setting, datasets commonly have well-defined sets of dimensions and measures around which analysis tasks can be conducted. However, many forms of data used in intelligence operations - deriving from social networks, online communications, and text corpora - will consist of graphs with varying forms of potential dimensional structure. Hence, enabling OLAP over such data collections requires explicit definition and extraction of supporting dimensions and measures. Further, as Graph OLAP remains an emerging technique, limited research has been done on its user interface requirements. Namely, on effective pairing of interface designs to different types of graph-derived dimensions and measures. This paper presents a novel technique for pairing of user interface designs to Graph OLAP datasets, rooted in Analytic Hierarchy Process (AHP) driven comparisons. Attributes of the classification strategy are encoded through an AHP ontology, developed in our alternate work and extended to support pairwise comparison of interfaces. Specifically, according to their ability, as perceived by Subject Matter Experts, to support dimensions and measures corresponding to Graph OLAP dataset attributes. To frame this discussion, a survey is provided both on existing variations of Graph OLAP, as well as existing interface designs previously applied in multidimensional analysis settings. Following this, a review of our AHP ontology is provided, along with a listing of corresponding dataset and interface attributes applicable toward SME recommendation structuring. A walkthrough of AHP-based recommendation encoding via the ontology-based approach is then provided. The paper concludes with a short summary of proposed future directions seen as essential for this research area.

Experimental shock deformation in zircon: a transmission electron microscopic study

NASA Astrophysics Data System (ADS)

Leroux, H.; Reimold, W. U.; Koeberl, C.; Hornemann, U.; Doukhan, J.-C.

1999-06-01

In recent years, apparently shock-induced and, thus, impact-characteristic microdeformations, in the form of planar microdeformation features and so-called strawberry (granular) texture, have been observed in zircons in rocks from confirmed impact structures and from the K/ T boundary. The nature of the planar microdeformations in this mineral is, however, still unknown, and critical information is needed regarding the shock pressure range in which these deformation effects are produced. We experimentally shock deformed two series of thin zircon (ZrSiO 4) target plates, cut perpendicular to the c-axis, at shock pressures of 20, 40, and 60 GPa. The recovered samples were characterized by optical and scanning electron microscopy. In addition, one sample series was studied by transmission electron microscopy (TEM). Microdeformation effects observed at 20 GPa include pervasive micro-cleavage and dislocation patterns. Plastic deformation is indicated by a high density of straight dislocations in glide configuration. The dominant glide systems are <100>{010}. Micro-cleavages, induced by shear stresses during the compression stage, occur mostly in the {100} planes. The large density of dislocations at crack tips shows that plastic deformation was initiated by the micro-cracking processs. At 40 GPa, the sample was partly transformed from the zircon (z) to a scheelite (CaWO 4)-type (s) structure. Planar deformation features (PDFs) containing an amorphous phase of zircon composition are present in the not yet transformed zircon relics. The phase with scheelite structure, initiated in the {100} planes of zircon, consists of thin (0.1 to several μm) bands that crosscut the zircon matrix. The phase transformation is displacive (martensitic) and can be related by {100} z // {112} s and [001] z // <110> s. The scheelite structure phase is densely twinned, with twins in the (112) plane. The 60-GPa sample consists completely of the scheelite structure phase. Crosscutting and displacing relationships between twins and PDFs demonstrate that PDFs are formed in the zircon structure, i.e., before the phase transformation to the scheelite structure occurred, most likely at the shock front. Crystallographic orientations of optically visible planar features in zircon, in comparison with orientations of planar defects at the TEM scale, suggest that the optically visible features are more likely planar microfractures than PDFs.

A fiber orientation-adapted integration scheme for computing the hyperelastic Tucker average for short fiber reinforced composites

NASA Astrophysics Data System (ADS)

Goldberg, Niels; Ospald, Felix; Schneider, Matti

2017-10-01

In this article we introduce a fiber orientation-adapted integration scheme for Tucker's orientation averaging procedure applied to non-linear material laws, based on angular central Gaussian fiber orientation distributions. This method is stable w.r.t. fiber orientations degenerating into planar states and enables the construction of orthotropic hyperelastic energies for truly orthotropic fiber orientation states. We establish a reference scenario for fitting the Tucker average of a transversely isotropic hyperelastic energy, corresponding to a uni-directional fiber orientation, to microstructural simulations, obtained by FFT-based computational homogenization of neo-Hookean constituents. We carefully discuss ideas for accelerating the identification process, leading to a tremendous speed-up compared to a naive approach. The resulting hyperelastic material map turns out to be surprisingly accurate, simple to integrate in commercial finite element codes and fast in its execution. We demonstrate the capabilities of the extracted model by a finite element analysis of a fiber reinforced chain link.

Creating Printed Materials for Mathematics with a Macintosh Computer.

ERIC Educational Resources Information Center

Mahler, Philip

This document gives instructions on how to use a Macintosh computer to create printed materials for mathematics. A Macintosh computer, Microsoft Word, and objected-oriented (Draw-type) art program, and a function-graphing program are capable of producing high quality printed instructional materials for mathematics. Word 5.1 has an equation editor…

Direct Visualization of Planar Assembly of Plasmonic Nanoparticles Adjacent to Electrodes in Oscillatory Electric Fields.

PubMed

Ferrick, Adam; Wang, Mei; Woehl, Taylor J

2018-05-29

Electric field-directed assembly of colloidal nanoparticles (NPs) has been widely adopted for fabricating functional thin films and nanostructured surfaces. While first-order electrokinetic effects on NPs are well-understood in terms of classical models, effects of second-order electrokinetics that involve induced surface charge are still poorly understood. Induced charge electroosmotic phenomena, such as electrohydrodynamic (EHD) flow, have long been implicated in electric field-directed NP assembly with little experimental basis. Here, we use in situ dark-field optical microscopy and plasmonic NPs to directly observe the dynamics of planar assembly of colloidal NPs adjacent to a planar electrode in low-frequency (<1 kHz) oscillatory electric fields. We exploit the change in plasmonic NP color resulting from interparticle plasmonic coupling to visualize the assembly dynamics and assembly structure of silver NPs. Planar assembly of NPs is unexpected because of strong electrostatic repulsion between NPs and indicates that there are strong attractive interparticle forces oriented perpendicular to the electric field direction. A parametric investigation of the voltage- and frequency-dependent phase behavior reveals that planar NP assembly occurs over a narrow frequency range below which irreversible ballistic deposition occurs. Two key experimental observations are consistent with EHD flow-induced NP assembly: (1) NPs remain mobile during assembly and (2) electron microscopy observations reveal randomly close-packed planar assemblies, consistent with strong interparticle attraction. We interpret planar assembly in terms of EHD fluid flow and develop a scaling model that qualitatively agrees with the measured phase regions. Our results are the first direct in situ observations of EHD flow-induced NP assembly and shed light on long-standing unresolved questions concerning the formation of NP superlattices during electric field-induced NP deposition.

Visualizing Ecosystem Energy Flow in Complex Food Web Networks: A Comparison of Three Alaskan Large Marine Ecosystems

NASA Astrophysics Data System (ADS)

Kearney, K.; Aydin, K.

2016-02-01

Oceanic food webs are often depicted as network graphs, with the major organisms or functional groups displayed as nodes and the fluxes of between them as the edges. However, the large number of nodes and edges and high connectance of many management-oriented food webs coupled with graph layout algorithms poorly-suited to certain desired characteristics of food web visualizations often lead to hopelessly tangled diagrams that convey little information other than, "It's complex." Here, I combine several new graph visualization techniques- including a new node layout alorithm based on a trophic similarity (quantification of shared predator and prey) and trophic level, divided edge bundling for edge routing, and intelligent automated placement of labels- to create a much clearer visualization of the important fluxes through a food web. The technique will be used to highlight the differences in energy flow within three Alaskan Large Marine Ecosystems (the Bering Sea, Gulf of Alaska, and Aleutian Islands) that include very similar functional groups but unique energy pathways.

Combinatorial compatibility as habit-controlling factor in lysozyme crystallization I. Monomeric and tetrameric F faces derived graph-theoretically

NASA Astrophysics Data System (ADS)

Strom, C. S.; Bennema, P.

1997-03-01

A series of two articles discusses possible morphological evidence for oligomerization of growth units in the crystallization of tetragonal lysozyme, based on a rigorous graph-theoretic derivation of the F faces. In the first study (Part I), the growth layers are derived as valid networks satisfying the conditions of F slices in the context of the PBC theory using the graph-theoretic method implemented in program FFACE [C.S. Strom, Z. Krist. 172 (1985) 11]. The analysis is performed in monomeric and alternative tetrameric and octameric formulations of the unit cell, assuming tetramer formation according to the strongest bonds. F (flat) slices with thickness Rdhkl ( {1}/{2} < R ≤ 1 ) are predicted theoretically in the forms 1 1 0, 0 1 1, 1 1 1. The relevant energies are established in the broken bond model. The relation between possible oligomeric specifications of the unit cell and combinatorially feasible F slice compositions in these orientations is explored.

A graph grammar approach to artificial life.

PubMed

Kniemeyer, Ole; Buck-Sorlin, Gerhard H; Kurth, Winfried

2004-01-01

We present the high-level language of relational growth grammars (RGGs) as a formalism designed for the specification of ALife models. RGGs can be seen as an extension of the well-known parametric Lindenmayer systems and contain rule-based, procedural, and object-oriented features. They are defined as rewriting systems operating on graphs with the edges coming from a set of user-defined relations, whereas the nodes can be associated with objects. We demonstrate their ability to represent genes, regulatory networks of metabolites, and morphologically structured organisms, as well as developmental aspects of these entities, in a common formal framework. Mutation, crossing over, selection, and the dynamics of a network of gene regulation can all be represented with simple graph rewriting rules. This is demonstrated in some detail on the classical example of Dawkins' biomorphs and the ABC model of flower morphogenesis: other applications are briefly sketched. An interactive program was implemented, enabling the execution of the formalism and the visualization of the results.

Multiscale field-aligned current analyzer

NASA Astrophysics Data System (ADS)

Bunescu, C.; Marghitu, O.; Constantinescu, D.; Narita, Y.; Vogt, J.; Blǎgǎu, A.

2015-11-01

The magnetosphere-ionosphere coupling is achieved, essentially, by a superposition of quasi-stationary and time-dependent field-aligned currents (FACs), over a broad range of spatial and temporal scales. The planarity of the FAC structures observed by satellite data and the orientation of the planar FAC sheets can be investigated by the well-established minimum variance analysis (MVA) of the magnetic perturbation. However, such investigations are often constrained to a predefined time window, i.e., to a specific scale of the FAC. The multiscale field-aligned current analyzer, introduced here, relies on performing MVA continuously and over a range of scales by varying the width of the analyzing window, appropriate for the complexity of the magnetic field signatures above the auroral oval. The proposed technique provides multiscale information on the planarity and orientation of the observed FACs. A new approach, based on the derivative of the largest eigenvalue of the magnetic variance matrix with respect to the length of the analysis window, makes possible the inference of the current structures' location (center) and scale (thickness). The capabilities of the FAC analyzer are explored analytically for the magnetic field profile of the Harris sheet and tested on synthetic FAC structures with uniform current density and infinite or finite geometry in the cross-section plane of the FAC. The method is illustrated with data observed by the Cluster spacecraft on crossing the nightside auroral region, and the results are cross checked with the optical observations from the Time History of Events and Macroscale Interactions during Substorms ground network.

An analysis of the sectorial influence of CSI300 stocks within the directed network

NASA Astrophysics Data System (ADS)

Mai, Yong; Chen, Huan; Meng, Lei

2014-02-01

This paper uses the Partial Correlation Planar maximally filtered Graph (PCPG) method to construct a directed network for the constituent stocks underlying the China Securities Index 300 (CSI300). We also analyse the impact of individual stocks. We find that the CSI300 market is a scale-free network with a relatively small power law exponent. The volatility of the stock prices has significant impact on other stocks. In the sectorial network, the industrial sector is the most influential one over other sectors, the financial sector only has a modest influence, while the telecommunication services sector’s influence is marginal. In addition, such inter-sector influence displays quarterly stability.

Positioning growth of NPB crystalline nanowires on the PTCDA nanocrystal template.

PubMed

Wang, Hong; Lin, Haiping; Fan, Xing; Ostendorp, Stefan; Wang, Yandong; Huang, Lizhen; Jiang, Lin; Li, Youyong; Wilde, Gerhard; Fuchs, Harald; Wang, Wenchong; Chi, Lifeng

2018-05-31

Non-planar organic molecules often form amorphous films via vapor phase deposition on surfaces. In this study, we demonstrate for the first time that direct crystalline growth of non-planar NPB is possible when the orientation of initially deposited molecules on a PTCDA nanocrystal template is controlled to make it analogous to the structure of the molecular crystal. The crystalline NPB nanowires can be further positioned by controlling the site-selective growth of PTCDA nanocrystal templates at pre-determined locations. Short channel bottom contact OFET array with the NPB nanowires directly grown on electrodes were subsequently fabricated. The hole mobility of NPB nanowires is improved by 40-fold in comparison to that of the amorphous films.

Dynamics of collision of a vortex ring and a planar surface

NASA Astrophysics Data System (ADS)

McErlean, Michael; Krane, Michael; Fontaine, Arnold

2009-11-01

The dynamics of the impact between a vortex ring and a planar surface orientated perpendicular to the direction of travel are presented. High Reynolds number vortex rings are injected into a quiescent tank of water using a piston-cylinder generator before colliding with a target at a long distance. Both the pressure at the stagnation point on the surface and the force imparted to the target by the ring impact are measured directly. The changes in both are related to the ring motion and deformation captured by high speed digital video, and DPIV measurements. These relations are used to develop a scaling law relation between impact force and vortex ring circulation, speed, and size.

Object recognition and pose estimation of planar objects from range data

NASA Technical Reports Server (NTRS)

Pendleton, Thomas W.; Chien, Chiun Hong; Littlefield, Mark L.; Magee, Michael

1994-01-01

The Extravehicular Activity Helper/Retriever (EVAHR) is a robotic device currently under development at the NASA Johnson Space Center that is designed to fetch objects or to assist in retrieving an astronaut who may have become inadvertently de-tethered. The EVAHR will be required to exhibit a high degree of intelligent autonomous operation and will base much of its reasoning upon information obtained from one or more three-dimensional sensors that it will carry and control. At the highest level of visual cognition and reasoning, the EVAHR will be required to detect objects, recognize them, and estimate their spatial orientation and location. The recognition phase and estimation of spatial pose will depend on the ability of the vision system to reliably extract geometric features of the objects such as whether the surface topologies observed are planar or curved and the spatial relationships between the component surfaces. In order to achieve these tasks, three-dimensional sensing of the operational environment and objects in the environment will therefore be essential. One of the sensors being considered to provide image data for object recognition and pose estimation is a phase-shift laser scanner. The characteristics of the data provided by this scanner have been studied and algorithms have been developed for segmenting range images into planar surfaces, extracting basic features such as surface area, and recognizing the object based on the characteristics of extracted features. Also, an approach has been developed for estimating the spatial orientation and location of the recognized object based on orientations of extracted planes and their intersection points. This paper presents some of the algorithms that have been developed for the purpose of recognizing and estimating the pose of objects as viewed by the laser scanner, and characterizes the desirability and utility of these algorithms within the context of the scanner itself, considering data quality and noise.

Basal ganglia and gait control: apomorphine administration and internal pallidum stimulation in Parkinson's disease.

PubMed

Grasso, R; Peppe, A; Stratta, F; Angelini, D; Zago, M; Stanzione, P; Lacquaniti, F

1999-05-01

Gait coordination was analyzed (four-camera 100 Hz ELITE system) in two groups of idiopathic Parkinson disease (PD) patients. Five patients underwent continuous infusion of apomorphine and were recorded in two different sessions (APO OFF and APO ON) in the same day. Three patients with a previous chronic electrode implantation in both internal globi pallidi (GPi) were recorded in the same experimental session with the electrodes on and off (STIM ON and STIM OFF). The orientation of both the trunk and the lower-limb segments was described with respect to the vertical in the sagittal plane. Lower-limb inter-segmental coordination was evaluated by analyzing the co-variation between thigh, shank, and foot elevation angles by means of orthogonal planar regression. At least 30 gait cycles per experimental condition were processed. We found that the trunk was bent forward in STIM OFF, whereas it was better aligned with the vertical in STIM ON in both PD groups. The legs never fully extended during the gait cycle in STIM OFF, whereas they extended before heel strike in STIM ON. The multisegmental coordination of the lower limb changed almost in parallel with the changes in trunk orientation. In STIM OFF, both the shape and the spatial orientation of the planar gait loops (thigh angle vs. shank angle vs. foot angle) differed from those of physiological locomotion, whereas in STIM ON the gait loop tended to resume features closer to the control. Switching the electrodes on and off in patients with GPi electrodes resulted in quasi-parallel changes of the trunk inclination and of the planar gait loop. The bulk of the data suggest that the basal-ganglia circuitry may be relevant in locomotion by providing an appropriate spatio-temporal framework for the control of posture and movement in a gravity-based body-centered frame of reference. Pallido-thalamic and/or pallido-mesencephalic pathways may influence the timing of the inter-segmental coordination for gait.

Protein domain organisation: adding order.

PubMed

Kummerfeld, Sarah K; Teichmann, Sarah A

2009-01-29

Domains are the building blocks of proteins. During evolution, they have been duplicated, fused and recombined, to produce proteins with novel structures and functions. Structural and genome-scale studies have shown that pairs or groups of domains observed together in a protein are almost always found in only one N to C terminal order and are the result of a single recombination event that has been propagated by duplication of the multi-domain unit. Previous studies of domain organisation have used graph theory to represent the co-occurrence of domains within proteins. We build on this approach by adding directionality to the graphs and connecting nodes based on their relative order in the protein. Most of the time, the linear order of domains is conserved. However, using the directed graph representation we have identified non-linear features of domain organization that are over-represented in genomes. Recognising these patterns and unravelling how they have arisen may allow us to understand the functional relationships between domains and understand how the protein repertoire has evolved. We identify groups of domains that are not linearly conserved, but instead have been shuffled during evolution so that they occur in multiple different orders. We consider 192 genomes across all three kingdoms of life and use domain and protein annotation to understand their functional significance. To identify these features and assess their statistical significance, we represent the linear order of domains in proteins as a directed graph and apply graph theoretical methods. We describe two higher-order patterns of domain organisation: clusters and bi-directionally associated domain pairs and explore their functional importance and phylogenetic conservation. Taking into account the order of domains, we have derived a novel picture of global protein organization. We found that all genomes have a higher than expected degree of clustering and more domain pairs in forward and reverse orientation in different proteins relative to random graphs with identical degree distributions. While these features were statistically over-represented, they are still fairly rare. Looking in detail at the proteins involved, we found strong functional relationships within each cluster. In addition, the domains tended to be involved in protein-protein interaction and are able to function as independent structural units. A particularly striking example was the human Jak-STAT signalling pathway which makes use of a set of domains in a range of orders and orientations to provide nuanced signaling functionality. This illustrated the importance of functional and structural constraints (or lack thereof) on domain organisation.

Modelling NDE pulse-echo inspection of misorientated planar rough defects using an elastic finite element method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pettit, J. R.; Lowe, M. J. S.; Walker, A. E.

2015-03-31

Pulse-echo ultrasonic NDE examination of large pressure vessel forgings is a design and construction code requirement in the power generation industry. Such inspections aim to size and characterise potential defects that may have formed during the forging process. Typically these defects have a range of orientations and surface roughnesses which can greatly affect ultrasonic wave scattering behaviour. Ultrasonic modelling techniques can provide insight into defect response and therefore aid in characterisation. However, analytical approaches to solving these scattering problems can become inaccurate, especially when applied to increasingly complex defect geometries. To overcome these limitations a elastic Finite Element (FE) methodmore » has been developed to simulate pulse-echo inspections of embedded planar defects. The FE model comprises a significantly reduced spatial domain allowing for a Monte-Carlo based approach to consider multiple realisations of defect orientation and surface roughness. The results confirm that defects aligned perpendicular to the path of beam propagation attenuate ultrasonic signals according to the level of surface roughness. However, for defects orientated away from this plane, surface roughness can increase the magnitude of the scattered component propagating back along the path of the incident beam. This study therefore highlights instances where defect roughness increases the magnitude of ultrasonic scattered signals, as opposed to attenuation which is more often assumed.« less

An Object-oriented Taxonomy of Medical Data Presentations

PubMed Central

Starren, Justin; Johnson, Stephen B.

2000-01-01

A variety of methods have been proposed for presenting medical data visually on computers. Discussion of and comparison among these methods have been hindered by a lack of consistent terminology. A taxonomy of medical data presentations based on object-oriented user interface principles is presented. Presentations are divided into five major classes—list, table, graph, icon, and generated text. These are subdivided into eight subclasses with simple inheritance and four subclasses with multiple inheritance. The various subclasses are reviewed and examples are provided. Issues critical to the development and evaluation of presentations are also discussed. PMID:10641959

Insight into Evolution, Processing and Performance of Multi-length-scale Structures in Planar Heterojunction Perovskite Solar Cells.

PubMed

Huang, Yu-Ching; Tsao, Cheng-Si; Cho, Yi-Ju; Chen, Kuan-Chen; Chiang, Kai-Ming; Hsiao, Sheng-Yi; Chen, Chang-Wen; Su, Chun-Jen; Jeng, U-Ser; Lin, Hao-Wu

2015-09-04

The structural characterization correlated to the processing control of hierarchical structure of planar heterojunction perovskite layer is still incomplete due to the limitations of conventional microscopy and X-ray diffraction. This present study performed the simultaneously grazing-incidence small-angle scattering and wide-angle scattering (GISAXS/GIWAXS) techniques to quantitatively probe the hierarchical structure of the planar heterojunction perovskite solar cells. The result is complementary to the currently microscopic study. Correlation between the crystallization behavior, crystal orientation, nano- and meso-scale internal structure and surface morphology of perovskite film as functions of various processing control parameters is reported for the first time. The structural transition from the fractal pore network to the surface fractal can be tuned by the chloride percentage. The GISAXS/GIWAXS measurement provides the comprehensive understanding of concurrent evolution of the film morphology and crystallization correlated to the high performance. The result can provide the insight into formation mechanism and rational synthesis design.

Insight into Evolution, Processing and Performance of Multi-length-scale Structures in Planar Heterojunction Perovskite Solar Cells

NASA Astrophysics Data System (ADS)

Huang, Yu-Ching; Tsao, Cheng-Si; Cho, Yi-Ju; Chen, Kuan-Chen; Chiang, Kai-Ming; Hsiao, Sheng-Yi; Chen, Chang-Wen; Su, Chun-Jen; Jeng, U.-Ser; Lin, Hao-Wu

2015-09-01

The structural characterization correlated to the processing control of hierarchical structure of planar heterojunction perovskite layer is still incomplete due to the limitations of conventional microscopy and X-ray diffraction. This present study performed the simultaneously grazing-incidence small-angle scattering and wide-angle scattering (GISAXS/GIWAXS) techniques to quantitatively probe the hierarchical structure of the planar heterojunction perovskite solar cells. The result is complementary to the currently microscopic study. Correlation between the crystallization behavior, crystal orientation, nano- and meso-scale internal structure and surface morphology of perovskite film as functions of various processing control parameters is reported for the first time. The structural transition from the fractal pore network to the surface fractal can be tuned by the chloride percentage. The GISAXS/GIWAXS measurement provides the comprehensive understanding of concurrent evolution of the film morphology and crystallization correlated to the high performance. The result can provide the insight into formation mechanism and rational synthesis design.

Domain-wall excitations in the two-dimensional Ising spin glass

NASA Astrophysics Data System (ADS)

Khoshbakht, Hamid; Weigel, Martin

2018-02-01

The Ising spin glass in two dimensions exhibits rich behavior with subtle differences in the scaling for different coupling distributions. We use recently developed mappings to graph-theoretic problems together with highly efficient implementations of combinatorial optimization algorithms to determine exact ground states for systems on square lattices with up to 10 000 ×10 000 spins. While these mappings only work for planar graphs, for example for systems with periodic boundary conditions in at most one direction, we suggest here an iterative windowing technique that allows one to determine ground states for fully periodic samples up to sizes similar to those for the open-periodic case. Based on these techniques, a large number of disorder samples are used together with a careful finite-size scaling analysis to determine the stiffness exponents and domain-wall fractal dimensions with unprecedented accuracy, our best estimates being θ =-0.2793 (3 ) and df=1.273 19 (9 ) for Gaussian couplings. For bimodal disorder, a new uniform sampling algorithm allows us to study the domain-wall fractal dimension, finding df=1.279 (2 ) . Additionally, we also investigate the distributions of ground-state energies, of domain-wall energies, and domain-wall lengths.

Heuristic urban transportation network design method, a multilayer coevolution approach

NASA Astrophysics Data System (ADS)

Ding, Rui; Ujang, Norsidah; Hamid, Hussain bin; Manan, Mohd Shahrudin Abd; Li, Rong; Wu, Jianjun

2017-08-01

The design of urban transportation networks plays a key role in the urban planning process, and the coevolution of urban networks has recently garnered significant attention in literature. However, most of these recent articles are based on networks that are essentially planar. In this research, we propose a heuristic multilayer urban network coevolution model with lower layer network and upper layer network that are associated with growth and stimulate one another. We first use the relative neighbourhood graph and the Gabriel graph to simulate the structure of rail and road networks, respectively. With simulation we find that when a specific number of nodes are added, the total travel cost ratio between an expanded network and the initial lower layer network has the lowest value. The cooperation strength Λ and the changeable parameter average operation speed ratio Θ show that transit users' route choices change dramatically through the coevolution process and that their decisions, in turn, affect the multilayer network structure. We also note that the simulated relation between the Gini coefficient of the betweenness centrality, Θ and Λ have an optimal point for network design. This research could inspire the analysis of urban network topology features and the assessment of urban growth trends.

Plane-Based Registration of Several Thousand Laser Scans on Standard Hardware

NASA Astrophysics Data System (ADS)

Wujanz, D.; Schaller, S.; Gielsdorf, F.; Gründig, L.

2018-05-01

The automatic registration of terrestrial laser scans appears to be a solved problem in science as well as in practice. However, this assumption is questionable especially in the context of large projects where an object of interest is described by several thousand scans. A critical issue inherently linked to this task is memory management especially if cloud-based registration approaches such as the ICP are being deployed. In order to process even thousands of scans on standard hardware a plane-based registration approach is applied. As a first step planar features are detected within the unregistered scans. This step drastically reduces the amount of data that has to be handled by the hardware. After determination of corresponding planar features a pairwise registration procedure is initiated based on a graph that represents topological relations among all scans. For every feature individual stochastic characteristics are computed that are consequently carried through the algorithm. Finally, a block adjustment is carried out that minimises the residuals between redundantly captured areas. The algorithm is demonstrated on a practical survey campaign featuring a historic town hall. In total, 4853 scans were registered on a standard PC with four processors (3.07 GHz) and 12 GB of RAM.

Minimum Interference Planar Geometric Topology in Wireless Sensor Networks

NASA Astrophysics Data System (ADS)

Nguyen, Trac N.; Huynh, Dung T.

The approach of using topology control to reduce interference in wireless sensor networks has attracted attention of several researchers. There are at least two definitions of interference in the literature. In a wireless sensor network the interference at a node may be caused by an edge that is transmitting data [15], or it occurs because the node itself is within the transmission range of another [3], [1], [6]. In this paper we show that the problem of assigning power to nodes in the plane to yield a planar geometric graph whose nodes have bounded interference is NP-complete under both interference definitions. Our results provide a rigorous proof for a theorem in [15] whose proof is unconvincing. They also address one of the open issues raised in [6] where Halldórsson and Tokuyama were concerned with the receiver model of node interference, and derived an O(sqrt {Δ}) upper bound for the maximum node interference of a wireless ad hoc network in the plane (Δ is the maximum interference of the so-called uniform radius network). The question as to whether this problem is NP-complete in the 2-dimensional case was left open.

3D Fiber Orientation Simulation for Plastic Injection Molding

NASA Astrophysics Data System (ADS)

Lin, Baojiu; Jin, Xiaoshi; Zheng, Rong; Costa, Franco S.; Fan, Zhiliang

2004-06-01

Glass fiber reinforced polymer is widely used in the products made using injection molding processing. The distribution of fiber orientation inside plastic parts has direct effects on quality of molded parts. Using computer simulation to predict fiber orientation distribution is one of most efficient ways to assist engineers to do warpage analysis and to find a good design solution to produce high quality plastic parts. Fiber orientation simulation software based on 2-1/2D (midplane /Dual domain mesh) techniques has been used in industry for a decade. However, the 2-1/2D technique is based on the planar Hele-Shaw approximation and it is not suitable when the geometry has complex three-dimensional features which cannot be well approximated by 2D shells. Recently, a full 3D simulation software for fiber orientation has been developed and integrated into Moldflow Plastics Insight 3D simulation software. The theory for this new 3D fiber orientation calculation module is described in this paper. Several examples are also presented to show the benefit in using 3D fiber orientation simulation.

Eigenvector synchronization, graph rigidity and the molecule problemR

PubMed Central

Cucuringu, Mihai; Singer, Amit; Cowburn, David

2013-01-01

The graph realization problem has received a great deal of attention in recent years, due to its importance in applications such as wireless sensor networks and structural biology. In this paper, we extend the previous work and propose the 3D-As-Synchronized-As-Possible (3D-ASAP) algorithm, for the graph realization problem in ℝ3, given a sparse and noisy set of distance measurements. 3D-ASAP is a divide and conquer, non-incremental and non-iterative algorithm, which integrates local distance information into a global structure determination. Our approach starts with identifying, for every node, a subgraph of its 1-hop neighborhood graph, which can be accurately embedded in its own coordinate system. In the noise-free case, the computed coordinates of the sensors in each patch must agree with their global positioning up to some unknown rigid motion, that is, up to translation, rotation and possibly reflection. In other words, to every patch, there corresponds an element of the Euclidean group, Euc(3), of rigid transformations in ℝ3, and the goal was to estimate the group elements that will properly align all the patches in a globally consistent way. Furthermore, 3D-ASAP successfully incorporates information specific to the molecule problem in structural biology, in particular information on known substructures and their orientation. In addition, we also propose 3D-spectral-partitioning (SP)-ASAP, a faster version of 3D-ASAP, which uses a spectral partitioning algorithm as a pre-processing step for dividing the initial graph into smaller subgraphs. Our extensive numerical simulations show that 3D-ASAP and 3D-SP-ASAP are very robust to high levels of noise in the measured distances and to sparse connectivity in the measurement graph, and compare favorably with similar state-of-the-art localization algorithms. PMID:24432187

Synthesis and orientation of barium hexaferrite ceramics by magnetic alignment

NASA Astrophysics Data System (ADS)

Autissier, Denis

1990-01-01

Particles of Ba 2Mn xZn 2- xFe 12O 22 with planar structure were prepared by chemical precipitation. They were processed by sleep casting in presence of a magnetic field. The degree of alignment was improved by a special sintering treatment. By this procedure an alignment as high as 99.9% is obtained.

3DXRD at the Advanced Photon Source: Orientation Mapping and Deformation Studies

DTIC Science & Technology

2010-09-01

statistics in the same sample (Hefferan et al. (2010)). This low orientation uncertainty or error bar might be surprising at first since we do measurements...may be a combination of noise and real gradients. Some of the intra‐ granular  disorder  in  (b)  should  be  interpreted  as  statistical   and  only...cooling (AC), but are not present after ice water quenching (IWQ). The presence of SRO domains is known to lead to planar slip bands during tensile

Distortions in memory for visual displays

NASA Technical Reports Server (NTRS)

Tversky, Barbara

1989-01-01

Systematic errors in perception and memory present a challenge to theories of perception and memory and to applied psychologists interested in overcoming them as well. A number of systematic errors in memory for maps and graphs are reviewed, and they are accounted for by an analysis of the perceptual processing presumed to occur in comprehension of maps and graphs. Visual stimuli, like verbal stimuli, are organized in comprehension and memory. For visual stimuli, the organization is a consequence of perceptual processing, which is bottom-up or data-driven in its earlier stages, but top-down and affected by conceptual knowledge later on. Segregation of figure from ground is an early process, and figure recognition later; for both, symmetry is a rapidly detected and ecologically valid cue. Once isolated, figures are organized relative to one another and relative to a frame of reference. Both perceptual (e.g., salience) and conceptual factors (e.g., significance) seem likely to affect selection of a reference frame. Consistent with the analysis, subjects perceived and remembered curves in graphs and rivers in maps as more symmetric than they actually were. Symmetry, useful for detecting and recognizing figures, distorts map and graph figures alike. Top-down processes also seem to operate in that calling attention to the symmetry vs. asymmetry of a slightly asymmetric curve yielded memory errors in the direction of the description. Conceptual frame of reference effects were demonstrated in memory for lines embedded in graphs. In earlier work, the orientation of map figures was distorted in memory toward horizontal or vertical. In recent work, graph lines, but not map lines, were remembered as closer to an imaginary 45 deg line than they had been. Reference frames are determined by both perceptual and conceptual factors, leading to selection of the canonical axes as a reference frame in maps, but selection of the imaginary 45 deg as a reference frame in graphs.

Shuttle-launch triangular space station

NASA Technical Reports Server (NTRS)

Schneider, W. C. (Inventor); Berka, R. B. (Inventor); Kavanaugh, C. (Inventor); Nagy, K. (Inventor); Parish, R. C. (Inventor); Schliesing, J. A. (Inventor); Smith, P. D. (Inventor); Stebbins, F. J. (Inventor); Wesselski, C. J. (Inventor)

1986-01-01

A triangular space station deployable in orbit is described. The framework is comprized of three trusses, formed of a pair of generally planar faces consistine of foldable struts. The struts expand and lock into rigid structural engagement forming a repetition of equilater triangles and nonfolding diagonal struts interconnecting the two faces. The struts are joined together by node fittings. The framework can be packaged into a size and configuration transportable by a space shuttle. When deployed, the framework provides a large work/construction area and ample planar surface area for solar panels and thermal radiators. A plurity of modules are secured to the framework and then joined by tunnels to make an interconnected modular display. Thruster units for the space station orientation and altitude maintenance are provided.

Planar cell polarity pathway in vertebrate epidermal development, homeostasis and repair

PubMed Central

Dworkin, Sebastian; Jane, Stephen M

2011-01-01

The planar cell polarity (PCP) pathway plays a critical role in diverse developmental processes that require coordinated cellular movement, including neural tube closure and renal tubulogenesis. Recent studies have demonstrated that this pathway also has emerging relevance to the epidermis, as PCP signaling underpins many aspects of skin biology and pathology, including epidermal development, hair orientation, stem cell division and cancer. Coordinated cellular movement required for epidermal repair in mammals is also regulated by PCP signaling, and in this context, a new PCP gene encoding the developmental transcription factor Grainyhead-like 3 (Grhl3) is critical. This review focuses on the role that PCP signaling plays in the skin across a variety of epidermal functions and highlights perturbations that induce epidermal pathologies. PMID:22041517

Reading Guided by Automated Graphical Representations: How Model-Based Text Visualizations Facilitate Learning in Reading Comprehension Tasks

ERIC Educational Resources Information Center

Pirnay-Dummer, Pablo; Ifenthaler, Dirk

2011-01-01

Our study integrates automated natural language-oriented assessment and analysis methodologies into feasible reading comprehension tasks. With the newly developed T-MITOCAR toolset, prose text can be automatically converted into an association net which has similarities to a concept map. The "text to graph" feature of the software is based on…

Job Knowledge Test Design: A Cognitively-Oriented Approach. Institute Report No. 241.

ERIC Educational Resources Information Center

DuBois, David; And Others

Selected cognitive science methods were used to modify existing test development procedures so that the modified procedures could in turn be used to improve the usefulness of job knowledge tests as a proxy for hands-on performance. A plan-goal graph representation was used to capture the knowledge content and goal structure of the task of using a…

The Effect of Varied Gender Groupings on Argumentation Skills among Middle School Students in Different Cultures

ERIC Educational Resources Information Center

Hsu, Pi-Sui; Van Dyke, Margot; Smith, Thomas J.

2017-01-01

The purpose of this mixed-methods study was to explore the effect of varied gender groupings on argumentation skills among middle school students in Taiwan and the United States in a project-based learning environment that incorporated a graph-oriented computer-assisted application (GOCAA). A total of 43 students comprised the treatment condition…

Horizontal high speed stacking for batteries with prismatic cans

DOEpatents

Bartos, Andrew L.; Lin, Yhu-Tin; Turner, III, Raymond D.

2016-06-14

A system and method for stacking battery cells or related assembled components. Generally planar, rectangular (prismatic-shaped) battery cells are moved from an as-received generally vertical stacking orientation to a generally horizontal stacking orientation without the need for robotic pick-and-place equipment. The system includes numerous conveyor belts that work in cooperation with one another to deliver, rotate and stack the cells or their affiliated assemblies. The belts are outfitted with components to facilitate the cell transport and rotation. The coordinated movement between the belts and the components promote the orderly transport and rotation of the cells from a substantially vertical stacking orientation into a substantially horizontal stacking orientation. The approach of the present invention helps keep the stacked assemblies stable so that subsequent assembly steps--such as compressing the cells or attaching electrical leads or thermal management components--may proceed with a reduced chance of error.

Fracture of single crystals of the nickel-base superalloy PWA 1480E in helium at 22 C

NASA Technical Reports Server (NTRS)

Chen, P. S.; Wilcox, R. C.

1991-01-01

The fracture behavior and deformation of He-charged (at 22 C) single crystals of PWA 1480E Ni-base superalloy were investigated using SEM and TEM techniques to observe the behavior of tensile fractures in notched single crystals with seven different crystal growth orientations: 100-line, 110-line, 111-line, 013-line, 112-line, 123-line, and 223-line. To identify the cleavage plane orientation, a stereoscopic technique, combined with the use of planar gamma-prime morphologies, was applied. It was found that gamma-prime particles were orderly and closely aligned with edges along the 100-line, 010-line, and 001-line-oriented directions of the gamma matrix. Different crystal growth orientations were found not to affect the morphology of gamma-prime particles. The accumulation of dislocations around gamma/gamma-prime interfaces formed strong barriers to subsequent dislocation movement and was the primary strengthening mechanism at room temperature.

Analysis of borehole-radar reflection logs from selected HC boreholes at the Project Shoal area, Churchill County, Nevada

USGS Publications Warehouse

Lane, J.W.; Joesten, P.K.; Pohll, G.M.; Mihevic, Todd

2001-01-01

Single-hole borehole-radar reflection logs were collected and interpreted in support of a study to characterize ground-water flow and transport at the Project Shoal Area (PSA) in Churchill County, Nevada. Radar logging was conducted in six boreholes using 60-MHz omni-directional electric-dipole antennas and a 60-MHz magnetic-dipole directional receiving antenna.Radar data from five boreholes were interpreted to identify the location, orientation, estimated length, and spatial continuity of planar reflectors present in the logs. The overall quality of the radar data is marginal and ranges from very poor to good. Twenty-seven reflectors were interpreted from the directional radar reflection logs. Although the range of orientation interpreted for the reflectors is large, a significant number of reflectors strike northeast-southwest and east-west to slightly northwest-southeast. Reflectors are moderate to steeply dipping and reflector length ranged from less than 7 m to more than 133 m.Qualitative scores were assigned to each reflector to provide a sense of the spatial continuity of the reflector and the characteristics of the field data relative to an ideal planar reflector (orientation score). The overall orientation scores are low, which reflects the general data quality, but also indicates that the properties of most reflectors depart from the ideal planar case. The low scores are consistent with reflections from fracture zones that contain numerous, closely spaced, sub-parallel fractures.Interpretation of borehole-radar direct-wave velocity and amplitude logs identified several characteristics of the logged boreholes: (1) low-velocity zones correlate with decreased direct-wave amplitude, indicating the presence of fracture zones; (2) direct-wave amplitude increases with depth in three of the boreholes, suggesting an increase in electrical resistivity with depth resulting from changes in mineral assemblage or from a decrease in the specific conductance of ground water; and (3) an increase in primary or secondary porosity and an associated change in mineral assemblage, or decrease in ground water specific conductance, was characterized in two of the boreholes below 300 m.The results of the radar reflection logging indicate that even where data quality is marginal, borehole-radar reflection logging can provide useful information for ground-water characterization studies in fractured rock and insights into the nature and extent of fractures and fracture zones in and near boreholes.

General planar transverse domain walls realized by optimized transverse magnetic field pulses in magnetic biaxial nanowires

NASA Astrophysics Data System (ADS)

Li, Mei; Wang, Jianbo; Lu, Jie

2017-02-01

The statics and field-driven dynamics of transverse domain walls (TDWs) in magnetic nanowires (NWs) have attracted continuous interests because of their theoretical significance and application potential in future magnetic logic and memory devices. Recent results demonstrate that uniform transverse magnetic fields (TMFs) can greatly enhance the wall velocity, meantime leave a twisting in the TDW azimuthal distribution. For application in high-density NW devices, it is preferable to erase the twisting so as to minimize magnetization frustrations. Here we report the realization of a completely planar TDW with arbitrary tilting attitude in a magnetic biaxial NW under a TMF pulse with fixed strength and well-designed orientation profile. We smooth any twisting in the TDW azimuthal plane thus completely decouple the polar and azimuthal degrees of freedom. The analytical differential equation describing the polar angle distribution is derived and the resulting solution is not the Walker-ansatz form. With this TMF pulse comoving, the field-driven dynamics of the planar TDW is investigated with the help of the asymptotic expansion method. It turns out the comoving TMF pulse increases the wall velocity under the same axial driving field. These results will help to design a series of modern magnetic devices based on planar TDWs.

Two-dimensional Ising model on random lattices with constant coordination number

NASA Astrophysics Data System (ADS)

Schrauth, Manuel; Richter, Julian A. J.; Portela, Jefferson S. E.

2018-02-01

We study the two-dimensional Ising model on networks with quenched topological (connectivity) disorder. In particular, we construct random lattices of constant coordination number and perform large-scale Monte Carlo simulations in order to obtain critical exponents using finite-size scaling relations. We find disorder-dependent effective critical exponents, similar to diluted models, showing thus no clear universal behavior. Considering the very recent results for the two-dimensional Ising model on proximity graphs and the coordination number correlation analysis suggested by Barghathi and Vojta [Phys. Rev. Lett. 113, 120602 (2014), 10.1103/PhysRevLett.113.120602], our results indicate that the planarity and connectedness of the lattice play an important role on deciding whether the phase transition is stable against quenched topological disorder.

Knotting fingerprints resolve knot complexity and knotting pathways in ideal knots.

PubMed

Hyde, David A B; Henrich, Joshua; Rawdon, Eric J; Millett, Kenneth C

2015-09-09

We use disk matrices to define knotting fingerprints that provide fine-grained insights into the local knotting structure of ideal knots. These knots have been found to have spatial properties that highly correlate with those of interesting macromolecules. From this fine structure and an analysis of the associated planar graph, one can define a measure of knot complexity using the number of independent unknotting pathways from the global knot type as the knot is trimmed progressively to a short arc unknot. A specialization of the Cheeger constant provides a measure of constraint on these independent unknotting pathways. Furthermore, the structure of the knotting fingerprint supports a comparison of the tight knot pathways to the unconstrained unknotting pathways of comparable length.

Adaptive distance metric learning for diffusion tensor image segmentation.

PubMed

Kong, Youyong; Wang, Defeng; Shi, Lin; Hui, Steve C N; Chu, Winnie C W

2014-01-01

High quality segmentation of diffusion tensor images (DTI) is of key interest in biomedical research and clinical application. In previous studies, most efforts have been made to construct predefined metrics for different DTI segmentation tasks. These methods require adequate prior knowledge and tuning parameters. To overcome these disadvantages, we proposed to automatically learn an adaptive distance metric by a graph based semi-supervised learning model for DTI segmentation. An original discriminative distance vector was first formulated by combining both geometry and orientation distances derived from diffusion tensors. The kernel metric over the original distance and labels of all voxels were then simultaneously optimized in a graph based semi-supervised learning approach. Finally, the optimization task was efficiently solved with an iterative gradient descent method to achieve the optimal solution. With our approach, an adaptive distance metric could be available for each specific segmentation task. Experiments on synthetic and real brain DTI datasets were performed to demonstrate the effectiveness and robustness of the proposed distance metric learning approach. The performance of our approach was compared with three classical metrics in the graph based semi-supervised learning framework.

Adaptive Distance Metric Learning for Diffusion Tensor Image Segmentation

PubMed Central

Kong, Youyong; Wang, Defeng; Shi, Lin; Hui, Steve C. N.; Chu, Winnie C. W.

2014-01-01

High quality segmentation of diffusion tensor images (DTI) is of key interest in biomedical research and clinical application. In previous studies, most efforts have been made to construct predefined metrics for different DTI segmentation tasks. These methods require adequate prior knowledge and tuning parameters. To overcome these disadvantages, we proposed to automatically learn an adaptive distance metric by a graph based semi-supervised learning model for DTI segmentation. An original discriminative distance vector was first formulated by combining both geometry and orientation distances derived from diffusion tensors. The kernel metric over the original distance and labels of all voxels were then simultaneously optimized in a graph based semi-supervised learning approach. Finally, the optimization task was efficiently solved with an iterative gradient descent method to achieve the optimal solution. With our approach, an adaptive distance metric could be available for each specific segmentation task. Experiments on synthetic and real brain DTI datasets were performed to demonstrate the effectiveness and robustness of the proposed distance metric learning approach. The performance of our approach was compared with three classical metrics in the graph based semi-supervised learning framework. PMID:24651858

Attributed relational graphs for cell nucleus segmentation in fluorescence microscopy images.

PubMed

Arslan, Salim; Ersahin, Tulin; Cetin-Atalay, Rengul; Gunduz-Demir, Cigdem

2013-06-01

More rapid and accurate high-throughput screening in molecular cellular biology research has become possible with the development of automated microscopy imaging, for which cell nucleus segmentation commonly constitutes the core step. Although several promising methods exist for segmenting the nuclei of monolayer isolated and less-confluent cells, it still remains an open problem to segment the nuclei of more-confluent cells, which tend to grow in overlayers. To address this problem, we propose a new model-based nucleus segmentation algorithm. This algorithm models how a human locates a nucleus by identifying the nucleus boundaries and piecing them together. In this algorithm, we define four types of primitives to represent nucleus boundaries at different orientations and construct an attributed relational graph on the primitives to represent their spatial relations. Then, we reduce the nucleus identification problem to finding predefined structural patterns in the constructed graph and also use the primitives in region growing to delineate the nucleus borders. Working with fluorescence microscopy images, our experiments demonstrate that the proposed algorithm identifies nuclei better than previous nucleus segmentation algorithms.

Inhomogeneous hard homonuclear molecules

NASA Astrophysics Data System (ADS)

Quintana, Jacqueline

A review is given of some features of theories for inhomogeneous fluids of nonspherical molecules that take as input the direct correlation function of the corresponding homogeneous system. Two different methods are described for defining the structure of hard homonuclear molecules close to a hard planar wall. A spherical harmonics expanison (SHE) within the integral equation (IE) method is presented and, for comparison, a version of density functional theory for orientable hard bodies. In both cases the Pynn-Lado model is employed and a comparison is made with Monte Carlo data. The results indicate that for hard molecules the IE approach does not always capture the effects of orientation due to the characteristics of the SHE for the step function. This disadvantage is particularly true in the case of the orientationally averaged density profile.

Center of mass perception and inertial frames of reference.

PubMed

Bingham, G P; Muchisky, M M

1993-11-01

Center of mass perception was investigated by varying the shape, size, and orientation of planar objects. Shape was manipulated to investigate symmetries as information. The number of reflective symmetry axes, the amount of rotational symmetry, and the presence of radial symmetry were varied. Orientation affected systematic errors. Judgments tended to undershoot the center of mass. Random errors increased with size and decreased with symmetry. Size had no effect on random errors for maximally symmetric objects, although orientation did. The spatial distributions of judgments were elliptical. Distribution axes were found to align with the principle moments of inertia. Major axes tended to align with gravity in maximally symmetric objects. A functional and physical account was given in terms of the repercussions of error. Overall, judgments were very accurate.

Automated Coarse Registration of Point Clouds in 3d Urban Scenes Using Voxel Based Plane Constraint

NASA Astrophysics Data System (ADS)

Xu, Y.; Boerner, R.; Yao, W.; Hoegner, L.; Stilla, U.

2017-09-01

For obtaining a full coverage of 3D scans in a large-scale urban area, the registration between point clouds acquired via terrestrial laser scanning (TLS) is normally mandatory. However, due to the complex urban environment, the automatic registration of different scans is still a challenging problem. In this work, we propose an automatic marker free method for fast and coarse registration between point clouds using the geometric constrains of planar patches under a voxel structure. Our proposed method consists of four major steps: the voxelization of the point cloud, the approximation of planar patches, the matching of corresponding patches, and the estimation of transformation parameters. In the voxelization step, the point cloud of each scan is organized with a 3D voxel structure, by which the entire point cloud is partitioned into small individual patches. In the following step, we represent points of each voxel with the approximated plane function, and select those patches resembling planar surfaces. Afterwards, for matching the corresponding patches, a RANSAC-based strategy is applied. Among all the planar patches of a scan, we randomly select a planar patches set of three planar surfaces, in order to build a coordinate frame via their normal vectors and their intersection points. The transformation parameters between scans are calculated from these two coordinate frames. The planar patches set with its transformation parameters owning the largest number of coplanar patches are identified as the optimal candidate set for estimating the correct transformation parameters. The experimental results using TLS datasets of different scenes reveal that our proposed method can be both effective and efficient for the coarse registration task. Especially, for the fast orientation between scans, our proposed method can achieve a registration error of less than around 2 degrees using the testing datasets, and much more efficient than the classical baseline methods.

Open-Access, Low-Magnetic-Field MRI System for Lung Research

NASA Technical Reports Server (NTRS)

Mair, Ross W.; Rosen, Matthew S.; Tsai, Leo L.; Walsworth, Ronald L.; Hrovat, Mirko I.; Patz, Samuel; Ruset, Iullian C.; Hersman, F. William

2009-01-01

An open-access magnetic resonance imaging (MRI) system is being developed for use in research on orientational/gravitational effects on lung physiology and function. The open-access geometry enables study of human subjects in diverse orientations. This system operates at a magnetic flux density, considerably smaller than the flux densities of typical other MRI systems, that can be generated by resistive electromagnet coils (instead of the more-expensive superconducting coils of the other systems). The human subject inhales air containing He-3 or Xe-129 atoms, the nuclear spins of which have been polarized by use of a laser beam to obtain a magnetic resonance that enables high-resolution gas space imaging at the low applied magnetic field. The system includes a bi-planar, constant-current, four-coil electromagnet assembly and associated electronic circuitry to apply a static magnetic field of 6.5 mT throughout the lung volume; planar coils and associated circuitry to apply a pulsed magnetic-field-gradient for each spatial dimension; a single, detachable radio-frequency coil and associated circuitry for inducing and detecting MRI signals; a table for supporting a horizontal subject; and electromagnetic shielding surrounding the electromagnet coils.

Graph theory approach to the eigenvalue problem of large space structures

NASA Technical Reports Server (NTRS)

Reddy, A. S. S. R.; Bainum, P. M.

1981-01-01

Graph theory is used to obtain numerical solutions to eigenvalue problems of large space structures (LSS) characterized by a state vector of large dimensions. The LSS are considered as large, flexible systems requiring both orientation and surface shape control. Graphic interpretation of the determinant of a matrix is employed to reduce a higher dimensional matrix into combinations of smaller dimensional sub-matrices. The reduction is implemented by means of a Boolean equivalent of the original matrices formulated to obtain smaller dimensional equivalents of the original numerical matrix. Computation time becomes less and more accurate solutions are possible. An example is provided in the form of a free-free square plate. Linearized system equations and numerical values of a stiffness matrix are presented, featuring a state vector with 16 components.

PerSubs: A Graph-Based Algorithm for the Identification of Perturbed Subpathways Caused by Complex Diseases.

PubMed

Vrahatis, Aristidis G; Rapti, Angeliki; Sioutas, Spyros; Tsakalidis, Athanasios

2017-01-01

In the era of Systems Biology and growing flow of omics experimental data from high throughput techniques, experimentalists are in need of more precise pathway-based tools to unravel the inherent complexity of diseases and biological processes. Subpathway-based approaches are the emerging generation of pathway-based analysis elucidating the biological mechanisms under the perspective of local topologies onto a complex pathway network. Towards this orientation, we developed PerSub, a graph-based algorithm which detects subpathways perturbed by a complex disease. The perturbations are imprinted through differentially expressed and co-expressed subpathways as recorded by RNA-seq experiments. Our novel algorithm is applied on data obtained from a real experimental study and the identified subpathways provide biological evidence for the brain aging.

A novel scene management technology for complex virtual battlefield environment

NASA Astrophysics Data System (ADS)

Sheng, Changchong; Jiang, Libing; Tang, Bo; Tang, Xiaoan

2018-04-01

The efficient scene management of virtual environment is an important research content of computer real-time visualization, which has a decisive influence on the efficiency of drawing. However, Traditional scene management methods do not suitable for complex virtual battlefield environments, this paper combines the advantages of traditional scene graph technology and spatial data structure method, using the idea of management and rendering separation, a loose object-oriented scene graph structure is established to manage the entity model data in the scene, and the performance-based quad-tree structure is created for traversing and rendering. In addition, the collaborative update relationship between the above two structural trees is designed to achieve efficient scene management. Compared with the previous scene management method, this method is more efficient and meets the needs of real-time visualization.

A new formation control of multiple underactuated surface vessels

NASA Astrophysics Data System (ADS)

Xie, Wenjing; Ma, Baoli; Fernando, Tyrone; Iu, Herbert Ho-Ching

2018-05-01

This work investigates a new formation control problem of multiple underactuated surface vessels. The controller design is based on input-output linearisation technique, graph theory, consensus idea and some nonlinear tools. The proposed smooth time-varying distributed control law guarantees that the multiple underactuated surface vessels globally exponentially converge to some desired geometric shape, which is especially centred at the initial average position of vessels. Furthermore, the stability analysis of zero dynamics proves that the orientations of vessels tend to some constants that are dependent on the initial values of vessels, and the velocities and control inputs of the vessels decay to zero. All the results are obtained under the communication scenarios of static directed balanced graph with a spanning tree. Effectiveness of the proposed distributed control scheme is demonstrated using a simulation example.

East Europe Report, Economic and Industrial Affairs, No. 2434.

DTIC Science & Technology

1983-08-11

lowering of debts made possible by the establishment of rational proportions between production and domestic consumption, may provide the roundation...The language makes it possible for the planners to formulate control tasks in the form of oriented graphs whose centers are control states and whose...were incapable of replacing with domestic production with rational expenditure. Naturally, import could be reduced below this level by administrative

A Study on Field Emission Characteristics of Planar Graphene Layers Obtained from a Highly Oriented Pyrolyzed Graphite Block

PubMed Central

2009-01-01

This paper describes an experimental study on field emission characteristics of individual graphene layers for vacuum nanoelectronics. Graphene layers were prepared by mechanical exfoliation from a highly oriented pyrolyzed graphite block and placed on an insulating substrate, with the resulting field emission behavior investigated using a nanomanipulator operating inside a scanning electron microscope. A pair of tungsten tips controlled by the nanomanipulator enabled electric connection with the graphene layers without postfabrication. The maximum emitted current from the graphene layers was 170 nA and the turn-on voltage was 12.1 V. PMID:20596315

Optimal control of orientation and entanglement for two dipole-dipole coupled quantum planar rotors.

PubMed

Yu, Hongling; Ho, Tak-San; Rabitz, Herschel

2018-05-09

Optimal control simulations are performed for orientation and entanglement of two dipole-dipole coupled identical quantum rotors. The rotors at various fixed separations lie on a model non-interacting plane with an applied control field. It is shown that optimal control of orientation or entanglement represents two contrasting control scenarios. In particular, the maximally oriented state (MOS) of the two rotors has a zero entanglement entropy and is readily attainable at all rotor separations. Whereas, the contrasting maximally entangled state (MES) has a zero orientation expectation value and is most conveniently attainable at small separations where the dipole-dipole coupling is strong. It is demonstrated that the peak orientation expectation value attained by the MOS at large separations exhibits a long time revival pattern due to the small energy splittings arising form the extremely weak dipole-dipole coupling between the degenerate product states of the two free rotors. Moreover, it is found that the peak entanglement entropy value attained by the MES remains largely unchanged as the two rotors are transported to large separations after turning off the control field. Finally, optimal control simulations of transition dynamics between the MOS and the MES reveal the intricate interplay between orientation and entanglement.

Embedded sensor having an identifiable orientation

DOEpatents

Bennett, Thomas E.; Nelson, Drew V.

2002-01-01

An apparatus and method is described wherein a sensor, such as a mechanical strain sensor, embedded in a fiber core, is "flagged" to identify a preferred orientation of the sensor. The identifying "flag" is a composite material, comprising a plurality of non-woven filaments distributed in a resin matrix, forming a small planar tab. The fiber is first subjected to a stimulus to identify the orientation providing the desired signal response, and then sandwiched between first and second layers of the composite material. The fiber, and therefore, the sensor orientation is thereby captured and fixed in place. The process for achieving the oriented fiber includes, after identifying the fiber orientation, carefully laying the oriented fiber onto the first layer of composite, moderately heating the assembled layer for a short period in order to bring the composite resin to a "tacky" state, heating the second composite layer as the first, and assembling the two layers together such that they merge to form a single consolidated block. The consolidated block achieving a roughly uniform distribution of composite filaments near the embedded fiber such that excess resin is prevented from "pooling" around the periphery of the fiber.

Planar waveguide integrated spatial filter array

NASA Astrophysics Data System (ADS)

Ai, Jun; Dimov, Fedor; Lyon, Richard; Rakuljic, Neven; Griffo, Chris; Xia, Xiaowei; Arik, Engin

2013-09-01

An innovative integrated spatial filter array (iSFA) was developed for the nulling interferometer for the detection of earth-like planets and life beyond our solar system. The coherent iSFA comprised a 2D planar lightwave circuit (PLC) array coupled with a pair of 2D lenslet arrays in a hexagonal grid to achieve the optimum fill factor and throughput. The silica-on-silicon waveguide mode field diameter and numerical aperture (NA) were designed to match with the Airy disc and NA of the microlens for optimum coupling. The lenslet array was coated with a chromium pinhole array at the focal plane to pass the single-mode waveguide but attenuate the higher modes. We assembled a 32 by 30 array by stacking 32 chips that were produced by photolithography from a 6-in. silicon wafer. Each chip has 30 planar waveguides. The PLC array is inherently polarization-maintaining (PM) and requires much less alignment in contrast to a fiber array, where each PM fiber must be placed individually and oriented correctly. The PLC array offers better scalability than the fiber bundle array for large arrays of over 1,000 waveguides.

Location of planar targets in three space from monocular images

NASA Technical Reports Server (NTRS)

Cornils, Karin; Goode, Plesent W.

1987-01-01

Many pieces of existing and proposed space hardware that would be targets of interest for a telerobot can be represented as planar or near-planar surfaces. Examples include the biostack modules on the Long Duration Exposure Facility, the panels on Solar Max, large diameter struts, and refueling receptacles. Robust and temporally efficient methods for locating such objects with sufficient accuracy are therefore worth developing. Two techniques that derive the orientation and location of an object from its monocular image are discussed and the results of experiments performed to determine translational and rotational accuracy are presented. Both the quadrangle projection and elastic matching techniques extract three-space information using a minimum of four identifiable target points and the principles of the perspective transformation. The selected points must describe a convex polygon whose geometric characteristics are prespecified in a data base. The rotational and translational accuracy of both techniques was tested at various ranges. This experiment is representative of the sensing requirements involved in a typical telerobot target acquisition task. Both techniques determined target location to an accuracy sufficient for consistent and efficient acquisition by the telerobot.

Trajectory Tracking of a Planer Parallel Manipulator by Using Computed Force Control Method

NASA Astrophysics Data System (ADS)

Bayram, Atilla

2017-03-01

Despite small workspace, parallel manipulators have some advantages over their serial counterparts in terms of higher speed, acceleration, rigidity, accuracy, manufacturing cost and payload. Accordingly, this type of manipulators can be used in many applications such as in high-speed machine tools, tuning machine for feeding, sensitive cutting, assembly and packaging. This paper presents a special type of planar parallel manipulator with three degrees of freedom. It is constructed as a variable geometry truss generally known planar Stewart platform. The reachable and orientation workspaces are obtained for this manipulator. The inverse kinematic analysis is solved for the trajectory tracking according to the redundancy and joint limit avoidance. Then, the dynamics model of the manipulator is established by using Virtual Work method. The simulations are performed to follow the given planar trajectories by using the dynamic equations of the variable geometry truss manipulator and computed force control method. In computed force control method, the feedback gain matrices for PD control are tuned with fixed matrices by trail end error and variable ones by means of optimization with genetic algorithm.

Distance-Dependent Sign Reversal in the Casimir-Lifshitz Torque

NASA Astrophysics Data System (ADS)

Thiyam, Priyadarshini; Parashar, Prachi; Shajesh, K. V.; Malyi, Oleksandr I.; Boström, Mathias; Milton, Kimball A.; Brevik, Iver; Persson, Clas

2018-03-01

The Casimir-Lifshitz torque between two biaxially polarizable anisotropic planar slabs is shown to exhibit a nontrivial sign reversal in its rotational sense. The critical distance ac between the slabs that marks this reversal is characterized by the frequency ωc˜c /2 ac at which the in-planar polarizabilities along the two principal axes are equal. The two materials seek to align their principal axes of polarizabilities in one direction below ac, while above ac their axes try to align rotated perpendicular relative to their previous minimum energy orientation. The sign reversal disappears in the nonretarded limit. Our perturbative result, derived for the case when the differences in the relative polarizabilities are small, matches excellently with the exact theory for uniaxial materials. We illustrate our results for black phosphorus and phosphorene.

Fabrication and Characterization of a Nanocoax-Based Electrochemical Sensor

NASA Astrophysics Data System (ADS)

Rizal, Binod; Archibald, Michelle M.; Naughton, Jeffrey R.; Connolly, Timothy; Shepard, Stephen C.; Burns, Michael J.; Chiles, Thomas C.; Naughton, Michael J.

2014-03-01

We used an imprint lithography process to fabricate three dimensional electrochemical sensors comprising arrays of vertically-oriented coaxial electrodes, with the coax cores and shields serving as working and counter electrodes, respectively, and with nanoscale separation gaps.[2] Arrays of devices with different electrode gaps (coax annuli) were prepared, yielding increasing sensitivity with decreasing annulus thickness. A coax-based sensor with a 100 nm annulus was found to have sensitivity 100 times greater than that of a conventional planar sensor control, which had millimeter-scale electrode gap spacing. We suggest that this enhancement is due to an increase in the diffusion of molecules between electrodes, which improves the current per unit surface area compared to the planar device. Supported by NIH (National Cancer Institute and the National Institute of Allergy and Infectious Diseases).

Planar optics with patterned chiral liquid crystals

NASA Astrophysics Data System (ADS)

Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

2016-06-01

Reflective metasurfaces based on metallic and dielectric nanoscatterers have attracted interest owing to their ability to control the phase of light. However, because such nanoscatterers require subwavelength features, the fabrication of elements that operate in the visible range is challenging. Here, we show that chiral liquid crystals with a self-organized helical structure enable metasurface-like, non-specular reflection in the visible region. The phase of light that is Bragg-reflected off the helical structure can be controlled over 0-2π depending on the spatial phase of the helical structure; thus planar elements with arbitrary reflected wavefronts can be created via orientation control. The circular polarization selectivity and external field tunability of Bragg reflection open a wide variety of potential applications for this family of functional devices, from optical isolators to wearable displays.

Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

PubMed Central

Marr, Isabella; Reiß, Sebastian; Hagen, Gunter; Moos, Ralf

2011-01-01

Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers. PMID:22164042

Four-port coupled channel-guide device based on 2D photonic crystal structure

NASA Astrophysics Data System (ADS)

Camargo, Edilson A.; Chong, Harold M. H.; De La Rue, Richard M.

2004-12-01

We have fabricated and measured a four-port coupled channel-waveguide device using W1 channel waveguides oriented along ΓK directions in a two-dimensional (2D) hole-based planar photonic crystal (PhC) based on silicon-on-insulator (SOI) waveguide material, at operation wavelengths around 1550 nm. 2D FDTD simulations and experimental results are shown and compared. The structure has been designed using a mode conversion approach, combined with coupled-mode concepts. The overall length of the photonic crystal structure is typically about 39 μm and the structure has been fabricated using a combination of direct-write electron-beam lithography (EBL) and dry-etch processing. Devices were measured using a tunable laser with end-fire coupling into the planar structure.

Energy Landscapes for the Self-Assembly of Supramolecular Polyhedra

NASA Astrophysics Data System (ADS)

Russell, Emily R.; Menon, Govind

2016-06-01

We develop a mathematical model for the energy landscape of polyhedral supramolecular cages recently synthesized by self-assembly (Sun et al. in Science 328:1144-1147, 2010). Our model includes two essential features of the experiment: (1) geometry of the organic ligands and metallic ions; and (2) combinatorics. The molecular geometry is used to introduce an energy that favors square-planar vertices (modeling {Pd}^{2+} ions) and bent edges with one of two preferred opening angles (modeling boomerang-shaped ligands of two types). The combinatorics of the model involve two-colorings of edges of polyhedra with four-valent vertices. The set of such two-colorings, quotiented by the octahedral symmetry group, has a natural graph structure and is called the combinatorial configuration space. The energy landscape of our model is the energy of each state in the combinatorial configuration space. The challenge in the computation of the energy landscape is a combinatorial explosion in the number of two-colorings of edges. We describe sampling methods based on the symmetries of the configurations and connectivity of the configuration graph. When the two preferred opening angles encompass the geometrically ideal angle, the energy landscape exhibits a very low-energy minimum for the most symmetric configuration at equal mixing of the two angles, even when the average opening angle does not match the ideal angle.

Solving Constraint-Satisfaction Problems with Distributed Neocortical-Like Neuronal Networks.

PubMed

Rutishauser, Ueli; Slotine, Jean-Jacques; Douglas, Rodney J

2018-05-01

Finding actions that satisfy the constraints imposed by both external inputs and internal representations is central to decision making. We demonstrate that some important classes of constraint satisfaction problems (CSPs) can be solved by networks composed of homogeneous cooperative-competitive modules that have connectivity similar to motifs observed in the superficial layers of neocortex. The winner-take-all modules are sparsely coupled by programming neurons that embed the constraints onto the otherwise homogeneous modular computational substrate. We show rules that embed any instance of the CSP's planar four-color graph coloring, maximum independent set, and sudoku on this substrate and provide mathematical proofs that guarantee these graph coloring problems will convergence to a solution. The network is composed of nonsaturating linear threshold neurons. Their lack of right saturation allows the overall network to explore the problem space driven through the unstable dynamics generated by recurrent excitation. The direction of exploration is steered by the constraint neurons. While many problems can be solved using only linear inhibitory constraints, network performance on hard problems benefits significantly when these negative constraints are implemented by nonlinear multiplicative inhibition. Overall, our results demonstrate the importance of instability rather than stability in network computation and offer insight into the computational role of dual inhibitory mechanisms in neural circuits.

Wnt/PCP Instructions for Cilia in Left-Right Asymmetry.

PubMed

Wu, Jun; Mlodzik, Marek

2017-03-13

Wnt-Frizzled/planar cell polarity (PCP) signaling establishes cell orientation within the epithelial plane, but whether Wnts are instructive or permissive is debated. Reporting in Developmental Cell, Minegishi et al. (2017) uncover an instructive link from Wnt5a/b gradients to PCP-factor-regulated polarized cilia positioning that is essential to mouse embryo left-right asymmetry establishment. Copyright © 2017. Published by Elsevier Inc.

Sensor-based monitoring and inspection of surface morphology in ultraprecision manufacturing processes

NASA Astrophysics Data System (ADS)

Rao, Prahalad Krishna

This research proposes approaches for monitoring and inspection of surface morphology with respect to two ultraprecision/nanomanufacturing processes, namely, ultraprecision machining (UPM) and chemical mechanical planarization (CMP). The methods illustrated in this dissertation are motivated from the compelling need for in situ process monitoring in nanomanufacturing and invoke concepts from diverse scientific backgrounds, such as artificial neural networks, Bayesian learning, and algebraic graph theory. From an engineering perspective, this work has the following contributions: 1. A combined neural network and Bayesian learning approach for early detection of UPM process anomalies by integrating data from multiple heterogeneous in situ sensors (force, vibration, and acoustic emission) is developed. The approach captures process drifts in UPM of aluminum 6061 discs within 15 milliseconds of their inception and is therefore valuable for minimizing yield losses. 2. CMP process dynamics are mathematically represented using a deterministic multi-scale hierarchical nonlinear differential equation model. This process-machine inter-action (PMI) model is evocative of the various physio-mechanical aspects in CMP and closely emulates experimentally acquired vibration signal patterns, including complex nonlinear dynamics manifest in the process. By combining the PMI model predictions with features gathered from wirelessly acquired CMP vibration signal patterns, CMP process anomalies, such as pad wear, and drifts in polishing were identified in their nascent stage with high fidelity (R2 ~ 75%). 3. An algebraic graph theoretic approach for quantifying nano-surface morphology from optical micrograph images is developed. The approach enables a parsimonious representation of the topological relationships between heterogeneous nano-surface fea-tures, which are enshrined in graph theoretic entities, namely, the similarity, degree, and Laplacian matrices. Topological invariant measures (e.g., Fiedler number, Kirchoff index) extracted from these matrices are shown to be sensitive to evolving nano-surface morphology. For instance, we observed that prominent nanoscale morphological changes on CMP processed Cu wafers, although discernible visually, could not be tractably quantified using statistical metrology parameters, such as arithmetic average roughness (Sa), root mean square roughness (Sq), etc. In contrast, CMP induced nanoscale surface variations were captured on invoking graph theoretic topological invariants. Consequently, the graph theoretic approach can enable timely, non-contact, and in situ metrology of semiconductor wafers by obviating the need for reticent profile mapping techniques (e.g., AFM, SEM, etc.), and thereby prevent the propagation of yield losses over long production runs.

A novel multi-planar radiography method for three dimensional pose reconstruction of the patellofemoral and tibiofemoral joints after arthroplasty.

PubMed

Amiri, Shahram; Wilson, David R; Masri, Bassam A; Sharma, Gulshan; Anglin, Carolyn

2011-06-03

Determining the 3D pose of the patella after total knee arthroplasty is challenging. The commonly used single-plane fluoroscopy is prone to large errors in the clinically relevant mediolateral direction. A conventional fixed bi-planar setup is limited in the minimum angular distance between the imaging planes necessary for visualizing the patellar component, and requires a highly flexible setup to adjust for the subject-specific geometries. As an alternative solution, this study investigated the use of a novel multi-planar imaging setup that consists of a C-arm tracked by an external optoelectric tracking system, to acquire calibrated radiographs from multiple orientations. To determine the accuracies, a knee prosthesis was implanted on artificial bones and imaged in simulated 'Supine' and 'Weightbearing' configurations. The results were compared with measures from a coordinate measuring machine as the ground-truth reference. The weightbearing configuration was the preferred imaging direction with RMS errors of 0.48 mm and 1.32 ° for mediolateral shift and tilt of the patella, respectively, the two most clinically relevant measures. The 'imaging accuracies' of the system, defined as the accuracies in 3D reconstruction of a cylindrical ball bearing phantom (so as to avoid the influence of the shape and orientation of the imaging object), showed an order of magnitude (11.5 times) reduction in the out-of-plane RMS errors in comparison to single-plane fluoroscopy. With this new method, complete 3D pose of the patellofemoral and tibiofemoral joints during quasi-static activities can be determined with a many-fold (up to 8 times) (3.4mm) improvement in the out-of-plane accuracies compared to a conventional single-plane fluoroscopy setup. Copyright © 2011 Elsevier Ltd. All rights reserved.

Navigation based on a sensorimotor representation: a virtual reality study

NASA Astrophysics Data System (ADS)

Zetzsche, Christoph; Galbraith, Christopher; Wolter, Johannes; Schill, Kerstin

2007-02-01

We investigate the hypothesis that the basic representation of space which underlies human navigation does not resemble an image-like map and is not restricted by the laws of Euclidean geometry. For this we developed a new experimental technique in which we use the properties of a virtual environment (VE) to directly influence the development of the representation. We compared the navigation performance of human observers under two conditions. Either the VE is consistent with the geometrical properties of physical space and could hence be represented in a map-like fashion, or it contains severe violations of Euclidean metric and planar topology, and would thus pose difficulties for the correct development of such a representation. Performance is not influenced by this difference, suggesting that a map-like representation is not the major basis of human navigation. Rather, the results are consistent with a representation which is similar to a non-planar graph augmented with path length information, or with a sensorimotor representation which combines sensory properties and motor actions. The latter may be seen as part of a revised view of perceptual processes due to recent results in psychology and neurobiology, which indicate that the traditional strict separation of sensory and motor systems is no longer tenable.

R-chie: a web server and R package for visualizing RNA secondary structures

PubMed Central

Lai, Daniel; Proctor, Jeff R.; Zhu, Jing Yun A.; Meyer, Irmtraud M.

2012-01-01

Visually examining RNA structures can greatly aid in understanding their potential functional roles and in evaluating the performance of structure prediction algorithms. As many functional roles of RNA structures can already be studied given the secondary structure of the RNA, various methods have been devised for visualizing RNA secondary structures. Most of these methods depict a given RNA secondary structure as a planar graph consisting of base-paired stems interconnected by roundish loops. In this article, we present an alternative method of depicting RNA secondary structure as arc diagrams. This is well suited for structures that are difficult or impossible to represent as planar stem-loop diagrams. Arc diagrams can intuitively display pseudo-knotted structures, as well as transient and alternative structural features. In addition, they facilitate the comparison of known and predicted RNA secondary structures. An added benefit is that structure information can be displayed in conjunction with a corresponding multiple sequence alignments, thereby highlighting structure and primary sequence conservation and variation. We have implemented the visualization algorithm as a web server R-chie as well as a corresponding R package called R4RNA, which allows users to run the software locally and across a range of common operating systems. PMID:22434875

a Numerical Investigation of the Jamming Transition in Traffic Flow on Diluted Planar Networks

NASA Astrophysics Data System (ADS)

Achler, Gabriele; Barra, Adriano

In order to develop a toy model for car's traffic in cities, in this paper we analyze, by means of numerical simulations, the transition among fluid regimes and a congested jammed phase of the flow of kinetically constrained hard spheres in planar random networks similar to urban roads. In order to explore as timescales as possible, at a microscopic level we implement an event driven dynamics as the infinite time limit of a class of already existing model (Follow the Leader) on an Erdos-Renyi two-dimensional graph, the crossroads being accounted by standard Kirchoff density conservations. We define a dynamical order parameter as the ratio among the moving spheres versus the total number and by varying two control parameters (density of the spheres and coordination number of the network) we study the phase transition. At a mesoscopic level it respects an, again suitable, adapted version of the Lighthill-Whitham model, which belongs to the fluid-dynamical approach to the problem. At a macroscopic level, the model seems to display a continuous transition from a fluid phase to a jammed phase when varying the density of the spheres (the amount of cars in a city-like scenario) and a discontinuous jump when varying the connectivity of the underlying network.

The regulation of focal adhesion complex formation and salivary gland epithelial cell organization by nanofibrous PLGA scaffolds

PubMed Central

Sequeira, Sharon J.; Soscia, David A.; Oztan, Basak; Mosier, Aaron P.; Jean-Gilles, Riffard; Gadre, Anand; Cady, Nathaniel C.; Yener, Bülent; Castracane, James; Larsen, Melinda

2012-01-01

Nanofiber scaffolds have been useful for engineering tissues derived from mesenchymal cells, but few studies have investigated their applicability for epithelial cell-derived tissues. In this study, we generated nanofiber (250 nm) or microfiber (1200 nm) scaffolds via electrospinning from the polymer, poly-L-lactic-co-glycolic acid (PLGA). Cell-scaffold contacts were visualized using fluorescent immunocytochemistry and laser scanning confocal microscopy. Focal adhesion (FA) proteins, such as phosphorylated FAK (Tyr397), paxillin (Tyr118), talin and vinculin were localized to FA complexes in adult cells grown on planar surfaces but were reduced and diffusely localized in cells grown on nanofiber surfaces, similar to the pattern observed in adult mouse salivary gland tissues. Significant differences in epithelial cell morphology and cell clustering were also observed and quantified, using image segmentation and computational cell-graph analyses. No statistically significant differences in scaffold stiffness between planar PLGA film controls compared to nanofibers scaffolds were detected using nanoindentation with atomic force microscopy, indicating that scaffold topography rather than mechanical properties accounts for changes in cell attachments and cell structure. Finally, PLGA nanofiber scaffolds could support the spontaneous self-organization and branching of dissociated embryonic salivary gland cells. Nanofiber scaffolds may therefore have applicability in the future for engineering an artificial salivary gland. PMID:22285464

Effects of bileaflet mechanical heart valve orientation on coronary flow

NASA Astrophysics Data System (ADS)

Haya, Laura; Tavoularis, Stavros

2015-11-01

The aortic sinus is approximately tri-radially symmetric, but bileaflet mechanical heart valves (BMHVs), which are commonly used to replace diseased aortic valves, are bilaterally symmetric. This mismatch in symmetry suggests that the orientation in which a BMHV is implanted within the aortic sinus affects the flow characteristics downstream of it. This study examines the effect of BMHV orientation on the flow in the coronary arteries, which originate in the aortic sinus and supply the heart tissue with blood. Planar particle image velocimetry measurements were made past a BMHV mounted at the inlet of an anatomical aorta model under physiological flow conditions. The complex interactions between the valve jets, the sinus vortex and the flow in the right coronary artery were elucidated for three valve orientations. The coronary flow rate was directly affected by the size, orientation, and time evolution of the vortex in the sinus, all of which were sensitive to the valve's orientation. The total flow through the artery was highest when the valve was oriented with its axis of symmetry intersecting the artery's opening. The findings of this research may assist surgeons in choosing the best orientation for BMHV implantation. The bileaflet valve was donated by St. Jude Medical. Financial support was provided by the Natural Sciences and Engineering Research Council of Canada.

Hierarchical image feature extraction by an irregular pyramid of polygonal partitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skurikhin, Alexei N

2008-01-01

We present an algorithmic framework for hierarchical image segmentation and feature extraction. We build a successive fine-to-coarse hierarchy of irregular polygonal partitions of the original image. This multiscale hierarchy forms the basis for object-oriented image analysis. The framework incorporates the Gestalt principles of visual perception, such as proximity and closure, and exploits spectral and textural similarities of polygonal partitions, while iteratively grouping them until dissimilarity criteria are exceeded. Seed polygons are built upon a triangular mesh composed of irregular sized triangles, whose spatial arrangement is adapted to the image content. This is achieved by building the triangular mesh on themore » top of detected spectral discontinuities (such as edges), which form a network of constraints for the Delaunay triangulation. The image is then represented as a spatial network in the form of a graph with vertices corresponding to the polygonal partitions and edges reflecting their relations. The iterative agglomeration of partitions into object-oriented segments is formulated as Minimum Spanning Tree (MST) construction. An important characteristic of the approach is that the agglomeration of polygonal partitions is constrained by the detected edges; thus the shapes of agglomerated partitions are more likely to correspond to the outlines of real-world objects. The constructed partitions and their spatial relations are characterized using spectral, textural and structural features based on proximity graphs. The framework allows searching for object-oriented features of interest across multiple levels of details of the built hierarchy and can be generalized to the multi-criteria MST to account for multiple criteria important for an application.« less

Weighted straight skeletons in the plane☆

PubMed Central

Biedl, Therese; Held, Martin; Huber, Stefan; Kaaser, Dominik; Palfrader, Peter

2015-01-01

We investigate weighted straight skeletons from a geometric, graph-theoretical, and combinatorial point of view. We start with a thorough definition and shed light on some ambiguity issues in the procedural definition. We investigate the geometry, combinatorics, and topology of faces and the roof model, and we discuss in which cases a weighted straight skeleton is connected. Finally, we show that the weighted straight skeleton of even a simple polygon may be non-planar and may contain cycles, and we discuss under which restrictions on the weights and/or the input polygon the weighted straight skeleton still behaves similar to its unweighted counterpart. In particular, we obtain a non-procedural description and a linear-time construction algorithm for the straight skeleton of strictly convex polygons with arbitrary weights. PMID:25648398

Discriminating tests of information and topological indices. Animals and trees.

PubMed

Konstantinova, Elena V; Vidyuk, Maxim V

2003-01-01

In this paper we consider 13 information and topological indices based on the distance in a molecular graph with respect to their discrimination power. The numerical results of discriminating tests on 3490528 trees up to 21 vertices are given. The indices of the highest sensitivity are listed on the set of 1528775 alkane trees. The discrimination powers of indices are also examined on the classes of 849285 hexagonal, 298382 square, and 295365 triangular simply connected animals. The first class of animals corresponds to the structural formulas of planar benzenoid hydrocarbons. The values of all indices were calculated for all classes of animals as well as for the united set of 1443032 animals. The inspection of the data indicates the great sensitivity of four information indices and one topological index.

Yangian symmetry for bi-scalar loop amplitudes

NASA Astrophysics Data System (ADS)

Chicherin, Dmitry; Kazakov, Vladimir; Loebbert, Florian; Müller, Dennis; Zhong, De-liang

2018-05-01

We establish an all-loop conformal Yangian symmetry for the full set of planar amplitudes in the recently proposed integrable bi-scalar field theory in four dimensions. This chiral theory is a particular double scaling limit of γ-twisted weakly coupled N=4 SYM theory. Each amplitude with a certain order of scalar particles is given by a single fishnet Feynman graph of disc topology cut out of a regular square lattice. The Yangian can be realized by the action of a product of Lax operators with a specific sequence of inhomogeneity parameters on the boundary of the disc. Based on this observation, the Yangian generators of level one for generic bi-scalar amplitudes are explicitly constructed. Finally, we comment on the relation to the dual conformal symmetry of these scattering amplitudes.

Job Knowledge Test Design: A Cognitively-Oriented Approach

DTIC Science & Technology

1993-07-01

protocol analyses and related methods. We employed a plan-goal graph representation to capture the knowledge content and goal structure of the studied task...between job knowledge and hands-on performance from previous studies was .38. For the subset of Marines in this sample who had recently been examined...the job knowledge test provided similar results to conventional, total number correct scoring. Conclusion The evidence provided by this study supports

Low cycle fatigue of MAR-M 200 single crystals at 760 and 870 deg C

NASA Technical Reports Server (NTRS)

Milligan, W. W.; Jayaraman, N.; Bill, R. C.

1984-01-01

Fully reversed low cycle fatigue tests were conducted on single crystals of the nickel-base superalloys Mar-M 200 at 760 C and 870 C. At 760 C, planar slip (octahedral) lead to orientation-dependent strain hardening and cyclic lives. Multiple slip crystals strain hardened the most, resulting in relatively high stress ranges and low lives. Single slip crystals strain hardened the least, resulting in relatively low stress ranges and higher lives. A preferential crack initiation site which was related to slip plane geometry was observed in single slip orientated crystals. At 870 C, the trends were quite different, and the slip character was much more homogeneous. As the tensile axis orientation deviated from 001 , the stress ranges increased and the cyclic lives decreased. Two possible mechanisms were proposed to explain the behavior: one is based on Takeuchi and Kuramoto's cube cross-slip model, and the other is based on orientation-dependent creep rates.

300% Enhancement of Carrier Mobility in Uniaxial-Oriented Perovskite Films Formed by Topotactic-Oriented Attachment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dong Hoe; Park, Jaehong; Li, Zhen

Organic-inorganic perovskites with intriguing optical and electrical properties have attracted significant research interests due to their excellent performance in optoelectronic devices. Recent efforts on preparing uniform and large-grain polycrystalline perovskite films have led to enhanced carrier lifetime up to several microseconds. However, the mobility and trap densities of polycrystalline perovskite films are still significantly behind their single-crystal counterparts. Here, a facile topotactic-oriented attachment (TOA) process to grow highly oriented perovskite films, featuring strong uniaxial-crystallographic texture, micrometer-grain morphology, high crystallinity, low trap density (≈4 x 10 14 cm -3), and unprecedented 9 GHz charge-carrier mobility (71 cm 2 V -1 smore » -1), is demonstrated. TOA-perovskite-based n-i-p planar solar cells show minimal discrepancies between stabilized efficiency (19.0%) and reverse-scan efficiency (19.7%). In conclusion, the TOA process is also applicable for growing other state-of-the-art perovskite alloys, including triple-cation and mixed-halide perovskites.« less

Chemically modified graphene/polyimide composite films based on utilization of covalent bonding and oriented distribution.

PubMed

Huang, Ting; Lu, Renguo; Su, Chao; Wang, Hongna; Guo, Zheng; Liu, Pei; Huang, Zhongyuan; Chen, Haiming; Li, Tongsheng

2012-05-01

Herein, we have developed a rather simple composite fabrication approach to achieving molecular-level dispersion and planar orientation of chemically modified graphene (CMG) in the thermosetting polyimide (PI) matrix as well as realizing strong adhesion at the interfacial regions between reinforcing filler and matrix. The covalent adhesion of CMG to PI matrix and oriented distribution of CMG were carefully confirmed and analyzed by detailed investigations. Combination of covalent bonding and oriented distribution could enlarge the effectiveness of CMG in the matrix. Efficient stress transfer was found at the CMG/PI interfaces. Significant improvements in the mechanical performances, thermal stability, electrical conductivity, and hydrophobic behavior were achieved by addition of only a small amount of CMG. Furthermore, it is noteworthy that the hydrophilic-to-hydrophobic transition and the electrical percolation were observed at only 0.2 wt % CMG in this composite system. This facile methodology is believed to afford broad application potential in graphene-based polymer nanocomposites, especially other types of high-performance thermosetting systems.

300% Enhancement of Carrier Mobility in Uniaxial-Oriented Perovskite Films Formed by Topotactic-Oriented Attachment

DOE PAGES

Kim, Dong Hoe; Park, Jaehong; Li, Zhen; ...

2017-04-18

Organic-inorganic perovskites with intriguing optical and electrical properties have attracted significant research interests due to their excellent performance in optoelectronic devices. Recent efforts on preparing uniform and large-grain polycrystalline perovskite films have led to enhanced carrier lifetime up to several microseconds. However, the mobility and trap densities of polycrystalline perovskite films are still significantly behind their single-crystal counterparts. Here, a facile topotactic-oriented attachment (TOA) process to grow highly oriented perovskite films, featuring strong uniaxial-crystallographic texture, micrometer-grain morphology, high crystallinity, low trap density (≈4 x 10 14 cm -3), and unprecedented 9 GHz charge-carrier mobility (71 cm 2 V -1 smore » -1), is demonstrated. TOA-perovskite-based n-i-p planar solar cells show minimal discrepancies between stabilized efficiency (19.0%) and reverse-scan efficiency (19.7%). In conclusion, the TOA process is also applicable for growing other state-of-the-art perovskite alloys, including triple-cation and mixed-halide perovskites.« less

Optical switch based on the electrically controlled liquid crystal interface.

PubMed

Komar, Andrei A; Tolstik, Alexei L; Melnikova, Elena A; Muravsky, Alexander A

2015-06-01

The peculiarities of the linearly polarized light beam reflection at the interface within the bulk of a nematic liquid crystal (NLC) cell with different orientations of the director are analyzed. Two methods to create the interface are considered. Combination of the planar and homeotropic orientations of the NLC director is realized by means of a spatially structured electrode under the applied voltage. In-plane patterned azimuthal alignment of the NLC director is created by the patterned rubbing alignment technique. All possible orthogonal orientations of the LC director are considered; the configurations for realization of total internal reflection are determined. The revealed relationship between the propagation of optical beams in a liquid crystal material and polarization of laser radiation has enabled realization of the spatial separation for the orthogonally polarized light beams at the interface between two regions of NLC with different director orientations (domains). Owing to variations in the applied voltage and, hence, in the refractive index gradient, the light beam propagation directions may be controlled electrically.

Three dimensional metafilms with dual channel unit cells

DOE PAGES

Burckel, D. Bruce; Campione, Salvatore; Davids, Paul S.; ...

2017-04-04

Three-dimensional (3D) metafilms composed of periodic arrays of silicon unit cells containing single and multiple micrometer-scale vertical split ring resonators (SRRs) per unit cell were fabricated. In contrast to planar and stacked planar structures, these 3D metafilms have a thickness t ~λ d/4, allowing for classical thin film effects in the long wavelength limit. The infrared specular far-field scattering response was measured for metafilms containing one and two resonators per unit cell and compared to numerical simulations. Excellent agreement in the frequency region below the onset of diffractive scattering was obtained. For dense arrays of unit cells containing single SRRs,more » normally incident linearly polarized plane waves which do not excite a resonant response result in thin film interference fringes in the reflected spectra and are virtually indistinguishable from the scattering response of an undecorated array of unit cells. For the resonant linear polarization, the specular reflection for arrays is highly dependent on the SRR orientation on the vertical face for gap-up, gap-down, and gap-right orientations. For dense arrays of unit cells containing two SRRs per unit cell positioned on adjacent faces, the specular reflection spectra are slightly modified due to near-field coupling between the orthogonally oriented SRRs but otherwise exhibit reflection spectra largely representative of the corresponding single-SRR unit cell structures. Lastly, the ability to pack the unit cell with multiple inclusions which can be independently excited by choice of incident polarization suggests the construction of dual-channel films where the scattering response is selected by altering the incident polarization.« less

Evolution of imitation networks in Minority Game model

NASA Astrophysics Data System (ADS)

Lavička, H.; Slanina, F.

2007-03-01

The Minority Game is adapted to study the “imitation dilemma”, i.e. the tradeoff between local benefit and global harm coming from imitation. The agents are placed on a substrate network and are allowed to imitate more successful neighbours. Imitation domains, which are oriented trees, are formed. We investigate size distribution of the domains and in-degree distribution within the trees. We use four types of substrate: one-dimensional chain; Erdös-Rényi graph; Barabási-Albert scale-free graph; Barabási-Albert 'model A' graph. The behaviour of some features of the imitation network strongly depend on the information cost epsilon, which is the percentage of gain the imitators must pay to the imitated. Generally, the system tends to form a few domains of equal size. However, positive epsilon makes the system stay in a long-lasting metastable state with complex structure. The in-degree distribution is found to follow a power law in two cases of those studied: for Erdös-Rényi substrate for any epsilon and for Barabási-Albert scale-free substrate for large enough epsilon. A brief comparison with empirical data is provided.

Aligned Immobilization of Proteins Using AC Electric Fields.

PubMed

Laux, Eva-Maria; Knigge, Xenia; Bier, Frank F; Wenger, Christian; Hölzel, Ralph

2016-03-01

Protein molecules are aligned and immobilized from solution by AC electric fields. In a single-step experiment, the enhanced green fluorescent proteins are immobilized on the surface as well as at the edges of planar nanoelectrodes. Alignment is found to follow the molecules' geometrical shape with their longitudinal axes parallel to the electric field. Simultaneous dielectrophoretic attraction and AC electroosmotic flow are identified as the dominant forces causing protein movement and alignment. Molecular orientation is determined by fluorescence microscopy based on polarized excitation of the proteins' chromophores. The chromophores' orientation with respect to the whole molecule supports X-ray crystal data. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gaussian Curvature Directs Stress Fiber Orientation and Cell Migration.

PubMed

Bade, Nathan D; Xu, Tina; Kamien, Randall D; Assoian, Richard K; Stebe, Kathleen J

2018-03-27

We show that substrates with nonzero Gaussian curvature influence the organization of stress fibers and direct the migration of cells. To study the role of Gaussian curvature, we developed a sphere-with-skirt surface in which a positive Gaussian curvature spherical cap is seamlessly surrounded by a negative Gaussian curvature draping skirt, both with principal radii similar to cell-length scales. We find significant reconfiguration of two subpopulations of stress fibers when fibroblasts are exposed to these curvatures. Apical stress fibers in cells on skirts align in the radial direction and avoid bending by forming chords across the concave gap, whereas basal stress fibers bend along the convex direction. Cell migration is also strongly influenced by the Gaussian curvature. Real-time imaging shows that cells migrating on skirts repolarize to establish a leading edge in the azimuthal direction. Thereafter, they migrate in that direction. This behavior is notably different from migration on planar surfaces, in which cells typically migrate in the same direction as the apical stress fiber orientation. Thus, this platform reveals that nonzero Gaussian curvature not only affects the positioning of cells and alignment of stress fiber subpopulations but also directs migration in a manner fundamentally distinct from that of migration on planar surfaces. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Giant anisotropic magnetoresistance and planar Hall effect in the Dirac semimetal Cd3As2

NASA Astrophysics Data System (ADS)

Li, Hui; Wang, Huan-Wen; He, Hongtao; Wang, Jiannong; Shen, Shun-Qing

2018-05-01

Anisotropic magnetoresistance is the change tendency of resistance of a material on the mutual orientation of the electric current and the external magnetic field. Here, we report experimental observations in the Dirac semimetal Cd3As2 of giant anisotropic magnetoresistance and its transverse version, called the planar Hall effect. The relative anisotropic magnetoresistance is negative and up to -68% at 2 K and 10 T. The high anisotropy and the minus sign in this isotropic and nonmagnetic material are attributed to a field-dependent current along the magnetic field, which may be induced by the Berry curvature of the band structure. This observation not only reveals unusual physical phenomena in Weyl and Dirac semimetals, but also finds additional transport signatures of Weyl and Dirac fermions other than negative magnetoresistance.

ANIE: A mathematical algorithm for automated indexing of planar deformation features in quartz grains

NASA Astrophysics Data System (ADS)

Huber, Matthew S.; Ferriãre, Ludovic; Losiak, Anna; Koeberl, Christian

2011-09-01

Abstract- Planar deformation features (PDFs) in quartz, one of the most commonly used diagnostic indicators of shock metamorphism, are planes of amorphous material that follow crystallographic orientations, and can thus be distinguished from non-shock-induced fractures in quartz. The process of indexing data for PDFs from universal-stage measurements has traditionally been performed using a manual graphical method, a time-consuming process in which errors can easily be introduced. A mathematical method and computer algorithm, which we call the Automated Numerical Index Executor (ANIE) program for indexing PDFs, was produced, and is presented here. The ANIE program is more accurate and faster than the manual graphical determination of Miller-Bravais indices, as it allows control of the exact error used in the calculation and removal of human error from the process.

Angle-dependent electron spin resonance of YbRh2Si2 measured with planar microwave resonators and in-situ rotation

NASA Astrophysics Data System (ADS)

Bondorf, Linda; Beutel, Manfred; Thiemann, Markus; Dressel, Martin; Bothner, Daniel; Sichelschmidt, Jörg; Kliemt, Kristin; Krellner, Cornelius; Scheffler, Marc

2018-05-01

We present a new experimental approach to investigate the magnetic properties of the anisotropic heavy-fermion system YbRh2Si2 as a function of crystallographic orientation. Angle-dependent electron spin resonance (ESR) measurements are performed at a low temperature of 1.6 K and at an ESR frequency of 4.4 GHz utilizing a superconducting planar microwave resonator in a 4He-cryostat in combination with in-situ sample rotation. The obtained ESR g-factor of YbRh2Si2 as a function of the crystallographic angle is consistent with results of previous measurements using conventional ESR spectrometers at higher frequencies and fields. Perspectives to implement this experimental approach into a dilution refrigerator and to reach the magnetically ordered phase of YbRh2Si2 are discussed.

Integration of planar cell polarity and ECM signaling in elongation of the vertebrate body plan.

PubMed

Skoglund, Paul; Keller, Ray

2010-10-01

The shaping of the vertebrate embryonic body plan depends heavily on the narrowing and lengthening (convergence and extension) of embryonic tissues by cell intercalation, a process by which cells actively crawl between one another along the axis of convergence to produce a narrower, longer array. We discuss recent evidence that the vertebrate non-canonical Wnt/Planar Cell Polarity (PCP) pathway, known to directly function in polarizing the movements of intercalating cells, is also involved in the localized assembly of extracellular matrix (ECM). These cell-ECM interactions, in turn, are necessary for expression of the oriented, polarized cell intercalation. The mechanism of PCP/ECM interactions, their molecular signaling, and their mechanical consequences for morphogenesis are discussed with the goal of identifying important unsolved issues. Copyright © 2010 Elsevier Ltd. All rights reserved.

Genetic analysis of ectopic growth suppression during planar growth of integuments mediated by the Arabidopsis AGC protein kinase UNICORN.

PubMed

Enugutti, Balaji; Schneitz, Kay

2013-01-02

The coordination of growth within a tissue layer is of critical importance for tissue morphogenesis. For example, cells within the epidermis undergo stereotypic cell divisions that are oriented along the plane of the layer (planar growth), thereby propagating the layered epidermal structure. Little is known about the developmental control that regulates such planar growth in plants. Recent evidence suggested that the Arabidopsis AGC VIII protein kinase UNICORN (UCN) maintains planar growth by suppressing the formation of ectopic multicellular protrusions in several floral tissues including integuments. In the current model UCN controls this process during integument development by directly interacting with the ABERRANT TESTA SHAPE (ATS) protein, a member of the KANADI (KAN) family of transcription factors, thereby repressing its activity. Here we report on the further characterization of the UCN mechanism. Phenotypic analysis of flowers of ucn-1 plants impaired in floral homeotic gene activity revealed that any of the four floral whorls could produce organs carrying ucn-1 protrusions. The ectopic outgrowths of ucn integuments did not accumulate detectable signals of the auxin and cytokinin reporters DR5rev::GFP and ARR5::GUS, respectively. Furthermore, wild-type and ucn-1 seedlings showed similarly strong callus formation upon in vitro culture on callus-inducing medium. We also show that ovules of ucn-1 plants carrying the dominant ats allele sk21-D exhibited more pronounced protrusion formation. Finally ovules of ucn-1 ett-1 double mutants and ucn-1 ett-1 arf4-1 triple mutants displayed an additive phenotype. These data deepen the molecular insight into the UCN-mediated control of planar growth during integument development. The presented evidence indicates that UCN downstream signaling does not involve the control of auxin or cytokinin homeostasis. The results also reveal that UCN interacts with ATS independently of an ATS/ETT complex required for integument initiation and they further emphasize the necessity to balance UCN and ATS proteins during maintenance of planar growth in integuments.

Graph-matching based CTA.

PubMed

Maksimov, Dmitry; Hesser, Jürgen; Brockmann, Carolin; Jochum, Susanne; Dietz, Tiina; Schnitzer, Andreas; Düber, Christoph; Schoenberg, Stefan O; Diehl, Steffen

2009-12-01

Separating bone, calcification, and vessels in computer tomography angiography (CTA) allows for a detailed diagnosis of vessel stenosis. This paper presents a new, graph-based technique that solves this difficult problem with high accuracy. The approach requires one native data set and one that is contrast enhanced. On each data set, an attributed level-graph is derived and both graphs are matched by dynamic programming to differentiate between bone, on one hand side, and vessel/calcification on the other hand side. Lumen and calcified regions are then separated by a profile technique. Evaluation is based on data from vessels of pelvis and lower extremities of elderly patients. Due to substantial calcification and motion of patients between and during the acquisitions, the underlying approach is tested on a class of difficult cases. Analysis requires 3-5 min on a Pentium IV 3 GHz for a 700 MByte data set. Among 37 patients, our approach correctly identifies all three components in 80% of cases correctly compared to visual control. Critical inconsistencies with visual inspection were found in 6% of all cases; 70% of these inconsistencies are due to small vessels that have 1) a diameter near the resolution of the CT and 2) are passing next to bony structures. All other remaining deviations are found in an incorrect handling of the iliac artery since the slice thickness is near the diameter of this vessel and since the orientation is not in cranio-caudal direction. Increasing resolution is thus expected to solve many the aforementioned difficulties.

Oriented cell division shapes carnivorous pitcher leaves of Sarracenia purpurea

PubMed Central

Fukushima, Kenji; Fujita, Hironori; Yamaguchi, Takahiro; Kawaguchi, Masayoshi; Tsukaya, Hirokazu; Hasebe, Mitsuyasu

2015-01-01

Complex morphology is an evolutionary outcome of phenotypic diversification. In some carnivorous plants, the ancestral planar leaf has been modified to form a pitcher shape. However, how leaf development was altered during evolution remains unknown. Here we show that the pitcher leaves of Sarracenia purpurea develop through cell division patterns of adaxial tissues that are distinct from those in bifacial and peltate leaves, subsequent to standard expression of adaxial and abaxial marker genes. Differences in the orientation of cell divisions in the adaxial domain cause bifacial growth in the distal region and adaxial ridge protrusion in the middle region. These different growth patterns establish pitcher morphology. A computer simulation suggests that the cell division plane is critical for the pitcher morphogenesis. Our results imply that tissue-specific changes in the orientation of cell division underlie the development of a morphologically complex leaf. PMID:25774486

Oriented cell division shapes carnivorous pitcher leaves of Sarracenia purpurea.

PubMed

Fukushima, Kenji; Fujita, Hironori; Yamaguchi, Takahiro; Kawaguchi, Masayoshi; Tsukaya, Hirokazu; Hasebe, Mitsuyasu

2015-03-16

Complex morphology is an evolutionary outcome of phenotypic diversification. In some carnivorous plants, the ancestral planar leaf has been modified to form a pitcher shape. However, how leaf development was altered during evolution remains unknown. Here we show that the pitcher leaves of Sarracenia purpurea develop through cell division patterns of adaxial tissues that are distinct from those in bifacial and peltate leaves, subsequent to standard expression of adaxial and abaxial marker genes. Differences in the orientation of cell divisions in the adaxial domain cause bifacial growth in the distal region and adaxial ridge protrusion in the middle region. These different growth patterns establish pitcher morphology. A computer simulation suggests that the cell division plane is critical for the pitcher morphogenesis. Our results imply that tissue-specific changes in the orientation of cell division underlie the development of a morphologically complex leaf.

A study on off-fault aftershock pattern at N-Adria microplate

NASA Astrophysics Data System (ADS)

Bressan, Gianni; Barnaba, Carla; Magrin, Andrea; Rossi, Giuliana

2018-03-01

The spatial features of the aftershock sequences triggered by three moderate magnitude events with coda-duration magnitudes 4.1, 5.1 and 5.6, which occurred in Northeastern Italy and Western Slovenia, were investigated. The fractal dimension and the orientations of the planar features fitting the hypocentral data have been inferred. The spatial organization is articulated through two temporal phases. The first phase is characterized by the decreasing of the fractal dimension and by vertically oriented planes fitting the hypocentral foci. The second phase is marked by an increase of the fractal dimension and by the activation of different planes, with more widespread orientation. The aftershock temporal distribution is analysed with a model based on a static fatigue process. The process is favoured by the decrease of the overburden pressure, the sharp variations of the mechanical properties of the medium and the unclamping effect resulting from positive normal stress changes caused by the mainshock stress step.

Ultra-wideband filtering of spoof surface plasmon polaritons using deep subwavelength planar structures

PubMed Central

Hu, Ming Zhe; Zhang, Hao Chi; Yin, Jia Yuan; Ding, Zhao; Liu, Jun Feng; Tang, Wen Xuan; Cui, Tie Jun

2016-01-01

Novel ultra-wideband filtering of spoof surface plasmon polaritons (SPPs) is proposed in the microwave frequency using deep subwavelength planar structures printed on thin and flexible dielectric substrate. The proposed planar SPPs waveguide is composed of two mirror-oriented metallic corrugated strips, which are further decorated with parallel-arranged slots in the main corrugated strips. This compound structure provides deep subwavelength field confinement as well as flexible parameters when employed as a plasmonic waveguide, which is potential to construct miniaturization. Using momentum and impedance matching technology, we achieve a smooth conversion between the proposed SPPs waveguide and the conventional transmission line. To verify the validity of the design, we fabricate a spoof SPPs filter, and the measured results illustrate excellent performance, in which the reflection coefficient is less than −10 dB within the −3 dB passband from 1.21 GHz to 7.21 GHz with the smallest insertion loss of 1.23 dB at 2.21 GHz, having very good agreements with numerical simulations. The ultra-wideband filter with low insertion loss and high transmission efficiency possesses great potential in modern communication systems. PMID:27883028

Ultra-wideband filtering of spoof surface plasmon polaritons using deep subwavelength planar structures.

PubMed

Hu, Ming Zhe; Zhang, Hao Chi; Yin, Jia Yuan; Ding, Zhao; Liu, Jun Feng; Tang, Wen Xuan; Cui, Tie Jun

2016-11-24

Novel ultra-wideband filtering of spoof surface plasmon polaritons (SPPs) is proposed in the microwave frequency using deep subwavelength planar structures printed on thin and flexible dielectric substrate. The proposed planar SPPs waveguide is composed of two mirror-oriented metallic corrugated strips, which are further decorated with parallel-arranged slots in the main corrugated strips. This compound structure provides deep subwavelength field confinement as well as flexible parameters when employed as a plasmonic waveguide, which is potential to construct miniaturization. Using momentum and impedance matching technology, we achieve a smooth conversion between the proposed SPPs waveguide and the conventional transmission line. To verify the validity of the design, we fabricate a spoof SPPs filter, and the measured results illustrate excellent performance, in which the reflection coefficient is less than -10 dB within the -3 dB passband from 1.21 GHz to 7.21 GHz with the smallest insertion loss of 1.23 dB at 2.21 GHz, having very good agreements with numerical simulations. The ultra-wideband filter with low insertion loss and high transmission efficiency possesses great potential in modern communication systems.

Simultaneous PIV and PLIF measurement of passive scalar mixing in a confined planar jet

NASA Astrophysics Data System (ADS)

Feng, Hua

2005-11-01

Simultaneous velocity and concentration fields in a confined liquid-phase planar jet with a Reynolds number based on hydraulic diameter of 50,000 were obtained using combined particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF). Data at six downstream locations were analyzed for flow statistics such as mean velocity, Reynolds stresses, turbulent kinetic energy, concentration mean and variance, turbulent fluxes, turbulent viscosity and diffusivity, and turbulent Schmidt number. Spatial correlation fields of turbulent fluxes and concentration were then determined. The Ru'φ' correlation was elliptical in shape with a major axis tilted downward with respect to the streamwise axis, whereas the Rv'φ' correlation was a horizontally oriented ellipse. The Rφ'φ' correlation field was found to be an ellipse with the major axis inclined at about 45-degrees with respect to the streamwise direction. Linear stochastic estimation was used to determine conditional flow structures. Large-scale structures were observed in the conditional velocity fields that are elliptical in shape with a streamwise major axis. The size of the structure initially increased linearly with respect to downstream distance, but then grew more slowly as the flow evolved towards channel flow.

Robust computation of dipole electromagnetic fields in arbitrarily anisotropic, planar-stratified environments.

PubMed

Sainath, Kamalesh; Teixeira, Fernando L; Donderici, Burkay

2014-01-01

We develop a general-purpose formulation, based on two-dimensional spectral integrals, for computing electromagnetic fields produced by arbitrarily oriented dipoles in planar-stratified environments, where each layer may exhibit arbitrary and independent anisotropy in both its (complex) permittivity and permeability tensors. Among the salient features of our formulation are (i) computation of eigenmodes (characteristic plane waves) supported in arbitrarily anisotropic media in a numerically robust fashion, (ii) implementation of an hp-adaptive refinement for the numerical integration to evaluate the radiation and weakly evanescent spectra contributions, and (iii) development of an adaptive extension of an integral convergence acceleration technique to compute the strongly evanescent spectrum contribution. While other semianalytic techniques exist to solve this problem, none have full applicability to media exhibiting arbitrary double anisotropies in each layer, where one must account for the whole range of possible phenomena (e.g., mode coupling at interfaces and nonreciprocal mode propagation). Brute-force numerical methods can tackle this problem but only at a much higher computational cost. The present formulation provides an efficient and robust technique for field computation in arbitrary planar-stratified environments. We demonstrate the formulation for a number of problems related to geophysical exploration.

Cyclone: java-based querying and computing with Pathway/Genome databases.

PubMed

Le Fèvre, François; Smidtas, Serge; Schächter, Vincent

2007-05-15

Cyclone aims at facilitating the use of BioCyc, a collection of Pathway/Genome Databases (PGDBs). Cyclone provides a fully extensible Java Object API to analyze and visualize these data. Cyclone can read and write PGDBs, and can write its own data in the CycloneML format. This format is automatically generated from the BioCyc ontology by Cyclone itself, ensuring continued compatibility. Cyclone objects can also be stored in a relational database CycloneDB. Queries can be written in SQL, and in an intuitive and concise object-oriented query language, Hibernate Query Language (HQL). In addition, Cyclone interfaces easily with Java software including the Eclipse IDE for HQL edition, the Jung API for graph algorithms or Cytoscape for graph visualization. Cyclone is freely available under an open source license at: http://sourceforge.net/projects/nemo-cyclone. For download and installation instructions, tutorials, use cases and examples, see http://nemo-cyclone.sourceforge.net.

Object-oriented integrated approach for the design of scalable ECG systems.

PubMed

Boskovic, Dusanka; Besic, Ingmar; Avdagic, Zikrija

2009-01-01

The paper presents the implementation of Object-Oriented (OO) integrated approaches to the design of scalable Electro-Cardio-Graph (ECG) Systems. The purpose of this methodology is to preserve real-world structure and relations with the aim to minimize the information loss during the process of modeling, especially for Real-Time (RT) systems. We report on a case study of the design that uses the integration of OO and RT methods and the Unified Modeling Language (UML) standard notation. OO methods identify objects in the real-world domain and use them as fundamental building blocks for the software system. The gained experience based on the strongly defined semantics of the object model is discussed and related problems are analyzed.

Tunnelling anomalous and planar Hall effects (Conference Presentation)

NASA Astrophysics Data System (ADS)

Matos-Abiague, Alex; Scharf, Benedikt; Han, Jong E.; Hankiewicz, Ewelina M.; Zutic, Igor

2016-10-01

We theoretically show how the interplay between spin-orbit coupling (SOC) and magnetism can result in a finite tunneling Hall conductance, transverse to the applied bias. For two-dimensional tunnel junctions with a ferromagnetic lead and magnetization perpendicular to the current flow, the detected anomalous Hall voltage can be used to extract information not only about the spin polarization but also about the strength of the interfacial SOC. In contrast, a tunneling current across a ferromagnetic barrier on the surface of a three-dimensional topological insulator (TI) can induce a planar Hall response even when the magnetization is oriented along the current flow[1]. The tunneling nature of the states contributing to the planar Hall conductance can be switched from the ordinary to the Klein regimes by the electrostatic control of the barrier strength. This allows for an enhancement of the transverse response and a giant Hall angle, with the tunneling planar Hall conductance exceeding the longitudinal component. Despite the simplicity of a single ferromagnetic region, the TI/ferromagnet system exhibits a variety of functionalities. In addition to a spin-valve operation for magnetic sensing and storing information, positive, negative, and negative differential conductances can be tuned by properly adjusting the barrier potential and/or varying the magnetization direction. Such different resistive behaviors in the same system are attractive for potential applications in reconfigurable spintronic devices. [1] B. Scharf, A. Matos-Abiague, J. E. Han, E. M. Hankiewicz, and I. Zutic, arXiv:1601.01009 (2016).

1-(4-Methyl-1-naphth­yl)ethanone

PubMed Central

Hu, Yong-Hong; Zhao, Xiao-Lei; Yang, Wen-Ge; Yao, Jin-Feng; Lu, Xiu-Tao

2008-01-01

In the mol­ecule of the title compound, C13H12O, the two aromatic rings are oriented at a dihedral angle of 2.90 (3)°. An intra­molecular C—H⋯O hydrogen bond results in the formation of a non-planar six-membered ring, which adopts an envelope conformation. In the crystal structure, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules. PMID:21581284

Effect of HF Heating Array Directivity Pattern on the Frequency Response of Generated ELF/VLF.

DTIC Science & Technology

1983-01-01

radiators ....... ............ 4 1-2 HF heating array ........ ................... 9 1-3 HF heating array element ...... ................ 9 1-4 View of top...elements looking down at pyramid ....... 9 1-5 Non-planar log-periodic antenna semi-structure dimensions ............ . ....... 10 l-6a Power gain vs...22 1-8 Orientation of 4- and 8-element arrays .. ......... .. 24 1- 9 Comparison of experimental and theoretical patterns. . . 27 1-10 Directive

Deformation of the Tonga Slab: Evidence for Interaction with a Small-scale Secondary Plume in the Transition Zone

NASA Astrophysics Data System (ADS)

Billen, M. I.; Bikoba, J. Z.; Tarlow, S.

2015-12-01

Magali I. Billen and John Z. BikobaThe Tonga Slab is the most seismically active subduction zone providing a uniquely detailed picture of the internal deformation of the slab, with apparent warping and folding, from the surface through the transition zone. Here, we investigate the dynamical origin of a irregular feature in the seismicity within the transition zone located at 21-28oS, using 3D visualization and analysis of the seismicity and compression/tension (P/T) axis from the moment tensor solutions to characterize the geometry of, and the orientation of forces acting on, the slab. This irregular feature can be described as narrow region of upward deflection of the slab, with a gap in seismicity beyond (down-dip of) the deflected region, and flanked by two narrow V-shaped gaps in seismicity suggestive of tearing of the slab. The P/T axis show a dominate down-dip orientation of the P axis above the deflection point, which rotate to a nearly vertical orientation within the central region of the deflected slab. The adjacent attached regions (down-dip of the two flanking slab gaps) also have rotated and more heterogeneous P/T axis orientations. In contrast, the adjacent section of the slab to the north of 21oS has continuous seismicity throughout the transition zone, with a roughly uniform planar shape, and generally down-dip orientation of the P axis. We explore three possible hypothesis for the observed deformation including: 1) deflection due to a buoyant metastable olivine wedge, 2) a buckling feature in the slab as previously proposed by Myhill (GJI., 2013), and interaction with a small-scale, secondary plume upwelling below the slab. If the newly-observed gaps in seismicity indicate physical gaps or significant thinning of the slab, then these observations are not consistent with the buckling hypothesis. The lack of significant along-strike variation in slab age or subduction rate also suggests that a localized region of metastable olivine is unlikely. Therefore, we test the third hypothesis using a simple 3D geodynamical model of a planar dipping slab overlying a localized buoyant upwelling (radius < 150 km). We present comparisons of the observations to the model predictions for the subsequent deformation of the slab and orientations of principal stress axis within the slab.

Fast Object Motion Estimation Based on Dynamic Stixels.

PubMed

Morales, Néstor; Morell, Antonio; Toledo, Jonay; Acosta, Leopoldo

2016-07-28

The stixel world is a simplification of the world in which obstacles are represented as vertical instances, called stixels, standing on a surface assumed to be planar. In this paper, previous approaches for stixel tracking are extended using a two-level scheme. In the first level, stixels are tracked by matching them between frames using a bipartite graph in which edges represent a matching cost function. Then, stixels are clustered into sets representing objects in the environment. These objects are matched based on the number of stixels paired inside them. Furthermore, a faster, but less accurate approach is proposed in which only the second level is used. Several configurations of our method are compared to an existing state-of-the-art approach to show how our methodology outperforms it in several areas, including an improvement in the quality of the depth reconstruction.

Omniview motionless camera orientation system

NASA Technical Reports Server (NTRS)

Martin, H. Lee (Inventor); Kuban, Daniel P. (Inventor); Zimmermann, Steven D. (Inventor); Busko, Nicholas (Inventor)

2010-01-01

An apparatus and method is provided for converting digital images for use in an imaging system. The apparatus includes a data memory which stores digital data representing an image having a circular or spherical field of view such as an image captured by a fish-eye lens, a control input for receiving a signal for selecting a portion of the image, and a converter responsive to the control input for converting digital data corresponding to the selected portion into digital data representing a planar image for subsequent display. Various methods include the steps of storing digital data representing an image having a circular or spherical field of view, selecting a portion of the image, and converting the stored digital data corresponding to the selected portion into digital data representing a planar image for subsequent display. In various embodiments, the data converter and data conversion step may use an orthogonal set of transformation algorithms.

An interplanetary planar magnetic structure oriented at a large (about 80 deg) angle to the Parker spiral

NASA Technical Reports Server (NTRS)

Farrugia, M. W.; Dunlop, M. W.; Geurts, F.; Balogh, A.; Southwood, D. J.; Bryant, D. A.; Neugebauer, M.

1990-01-01

Magnetic field structures in the solar wind, characterized by a variation of the field vectors within a plane inclined to the ecliptic ('Planar Magnetic Structures', PMSs), were reported recently (Nakagawa et al., 1989). These PMSs have the property that the plane of variation of the field also contains the nominal Parker spiral direction. An observation of a PMS where the direction of the line of intersection of the plane of field variation with the ecliptic plane makes a large (about 80 deg) angle to the Parker spiral direction is presented. Furthermore, the angular variables of the field (1) vary over a restricted range, and (2) are linearly related. The latter property is related to the former. Currently proposed models for the origin of PMS, inasmuch as they require field configurations which retain strict alignment with the Parker spiral direction from formation to observation, are probably incomplete.

Eigenvalue sensitivity analysis of planar frames with variable joint and support locations

NASA Technical Reports Server (NTRS)

Chuang, Ching H.; Hou, Gene J. W.

1991-01-01

Two sensitivity equations are derived in this study based upon the continuum approach for eigenvalue sensitivity analysis of planar frame structures with variable joint and support locations. A variational form of an eigenvalue equation is first derived in which all of the quantities are expressed in the local coordinate system attached to each member. Material derivative of this variational equation is then sought to account for changes in member's length and orientation resulting form the perturbation of joint and support locations. Finally, eigenvalue sensitivity equations are formulated in either domain quantities (by the domain method) or boundary quantities (by the boundary method). It is concluded that the sensitivity equation derived by the boundary method is more efficient in computation but less accurate than that of the domain method. Nevertheless, both of them in terms of computational efficiency are superior to the conventional direct differentiation method and the finite difference method.

Growth and quantum transport properties of vertical Bi2Se3 nanoplate films on Si substrates.

PubMed

Li, Mingze; Wang, Zhenhua; Yang, Liang; Pan, Desheng; Li, Da; Gao, Xuan P A; Zhang, Zhidong

2018-08-03

Controlling the growth direction (planar versus vertical) and surface-to-bulk ratio can lead to lots of unique properties for two-dimensional layered materials. We report a simple method to fabricate continuous films of vertical Bi 2 Se 3 nanoplates on Si substrate and investigate the quantum transport properties of such films. In contrast to (001) oriented planar Bi 2 Se 3 nanoplate film, vertical Bi 2 Se 3 nanoplate films are enclosed by (015) facets, which possess high surface-to-bulk ratio that can enhance the quantum transport property of topological surface states. And by controlling the compactness of vertical Bi 2 Se 3 nanoplates, we realized an effective tuning of the weak antilocalization effect from topological surface states in Bi 2 Se 3 films. Our work paves a way for exploring the unique transport properties of this unconventional structure topological insulator film.

Temperature effects on drift of suspended single-domain particles induced by the Magnus force

NASA Astrophysics Data System (ADS)

Denisov, S. I.; Lyutyy, T. V.; Reva, V. V.; Yermolenko, A. S.

2018-03-01

We study the temperature dependence of the drift velocity of single-domain ferromagnetic particles induced by the Magnus force in a dilute suspension. A set of stochastic equations describing the translational and rotational dynamics of particles is derived, and the particle drift velocity that depends on components of the average particle magnetization is introduced. The Fokker-Planck equation for the probability density of magnetization orientations is solved analytically in the limit of strong thermal fluctuations for both the planar rotor and general models. Using these solutions, we calculate the drift velocity and show that the out-of-plane fluctuations of magnetization, which are not accounted for in the planar rotor model, play an important role. In the general case of arbitrary fluctuations, we investigate the temperature dependence of the drift velocity by numerically simulating a set of effective stochastic differential equations for the magnetization dynamics.

Shock response of 7068 aluminium alloy

NASA Astrophysics Data System (ADS)

Chapman, David; Eakins, Daniel; Proud, William

2013-06-01

Aluminium alloys are widely employed throughout the aerospace and defence industries due to their high specific strength. Aluminium alloy 7068, often described as the ultimate aluminium alloy was developed by Kasier Aluminium in the mid-1990s and is the strongest aluminium commercially produced. There remains little published data on the response of this micro-structurally anisotropic alloy to dynamic loading. As part of an investigation of the high-rate mechanical properties of Al 7068, a series of plate-impact experiments using a novel meso-scale planar impact facility and a more conventional large bore gas gun were undertaken. The evolution of the elastic-plastic shock wave and spall strength as a function of sample thickness and specimen orientation were investigated using optical velocimetry (line-VISAR, PDV) techniques. Planar shock wave experiments were conducted on specimens several 100 microns to several millimetres thick cut from either parallel or perpendicular to the extrusion direction.

Planar waveguide concentrator used with a seasonal tracker.

PubMed

Bouchard, Sébastien; Thibault, Simon

2012-10-01

Solar concentrators offer good promise for reducing the cost of solar power. Planar waveguides equipped with a microlens slab have already been proposed as an excellent approach to produce medium to high concentration levels. Instead, we suggest the use of a cylindrical microlens array to get useful concentration without tracking during the day. To use only a seasonal tracking system and get the highest possible concentration, cylindrical microlenses are placed in the east-west orientation. Our new design has an acceptance angle in the north-south direction of ±9° and ±54° in the east-west axis. Simulation of our optimized system achieves a 4.6× average concentration level from 8:30 to 16:30 with a maximum of 8.1× and 80% optical efficiency. The low-cost advantage of waveguide-based solar concentrators could support their use in roof-mounted solar panels and eliminate the need for an expensive and heavy active tracker.

Photovoltaic array space power plus diagnostics experiment

NASA Technical Reports Server (NTRS)

Guidice, Donald A.

1990-01-01

The objective of the Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) experiment is to measure the effects of the interaction of the low- to mid-altitude space environment on the performance of a diverse set of small solar-cell arrays (planar and concentrator, representative of present and future military technologies) under differing conditions of velocity-vector orientation and simulated (by biasing) high-voltage operation. Solar arrays to be tested include Si and GaAs planar arrays and several types of GaAs concentrator arrays. Diagnostics (a Langmuir probe and a pressure gauge) and a transient pulse monitor (to measure radiated and conducted EMI during arcing) will be used to determine the impact of the environment on array operation to help verify various interactions models. Results from a successful PASP Plus flight will furnish answers to important interactions questions and provide inputs for design and test standards for photovoltaic space-power subsystems.

Neural field model to reconcile structure with function in primary visual cortex.

PubMed

Rankin, James; Chavane, Frédéric

2017-10-01

Voltage-sensitive dye imaging experiments in primary visual cortex (V1) have shown that local, oriented visual stimuli elicit stable orientation-selective activation within the stimulus retinotopic footprint. The cortical activation dynamically extends far beyond the retinotopic footprint, but the peripheral spread stays non-selective-a surprising finding given a number of anatomo-functional studies showing the orientation specificity of long-range connections. Here we use a computational model to investigate this apparent discrepancy by studying the expected population response using known published anatomical constraints. The dynamics of input-driven localized states were simulated in a planar neural field model with multiple sub-populations encoding orientation. The realistic connectivity profile has parameters controlling the clustering of long-range connections and their orientation bias. We found substantial overlap between the anatomically relevant parameter range and a steep decay in orientation selective activation that is consistent with the imaging experiments. In this way our study reconciles the reported orientation bias of long-range connections with the functional expression of orientation selective neural activity. Our results demonstrate this sharp decay is contingent on three factors, that long-range connections are sufficiently diffuse, that the orientation bias of these connections is in an intermediate range (consistent with anatomy) and that excitation is sufficiently balanced by inhibition. Conversely, our modelling results predict that, for reduced inhibition strength, spurious orientation selective activation could be generated through long-range lateral connections. Furthermore, if the orientation bias of lateral connections is very strong, or if inhibition is particularly weak, the network operates close to an instability leading to unbounded cortical activation.

Final Report on Contract F30602-91-C-0037 (Massachusetts University)

DTIC Science & Technology

1991-01-01

multiple levels of rmpresetion. Recognitio graphs control both hypothnes tranaoe-mation and hypothesm venlcatso., as shown in Figure 4, The premise 9...knowledge base, one that estimates distance based on the apparent width of a window and the estimated angle of the building face , and a second that...the orientation of the building face is not needed to estimate distance from the building’s height). Of course, since any two points on the object

GoFFish: Graph-Oriented Framework for Foresight and Insight Using Scalable Heuristics

DTIC Science & Technology

2015-09-01

series of research challenges that arise from the above and related to: scalability, data partitioning, memory representation and storage, exe - cution...job with varied deadlines in Jan, 2013. Further, we also build an SPSP model using Jan, 2013 data post facto as an ideal case. Fig. 7 reports the...Advanced Studies on Collaborative Research . Riverton, NJ, USA: IBM Corp., 2009, pp. 101–111. [42] G. J. Nutt, “The evolution towards flexible workflow

CW dipolar broadening EPR spectroscopy and mechanically aligned bilayers used to measure distance and relative orientation between two TOAC spin labels on an antimicrobial peptide

NASA Astrophysics Data System (ADS)

Sahu, Indra D.; Hustedt, Eric J.; Ghimire, Harishchandra; Inbaraj, Johnson J.; McCarrick, Robert M.; Lorigan, Gary A.

2014-12-01

An EPR membrane alignment technique was applied to measure distance and relative orientations between two spin labels on a protein oriented along the surface of the membrane. Previously we demonstrated an EPR membrane alignment technique for measuring distances and relative orientations between two spin labels using a dual TOAC-labeled integral transmembrane peptide (M2δ segment of Acetylcholine receptor) as a test system. In this study we further utilized this technique and successfully measured the distance and relative orientations between two spin labels on a membrane peripheral peptide (antimicrobial peptide magainin-2). The TOAC-labeled magainin-2 peptides were mechanically aligned using DMPC lipids on a planar quartz support, and CW-EPR spectra were recorded at specific orientations. Global analysis in combination with rigorous spectral simulation was used to simultaneously analyze data from two different sample orientations for both single- and double-labeled peptides. We measured an internitroxide distance of 15.3 Å from a dual TOAC-labeled magainin-2 peptide at positions 8 and 14 that closely matches with the 13.3 Å distance obtained from a model of the labeled magainin peptide. In addition, the angles determining the relative orientations of the two nitroxides have been determined, and the results compare favorably with molecular modeling. This study demonstrates the utility of the technique for proteins oriented along the surface of the membrane in addition to the previous results for proteins situated within the membrane bilayer.

View-Based Organization and Interplay of Spatial Working and Long-Term Memories

PubMed Central

Röhrich, Wolfgang G.; Hardiess, Gregor; Mallot, Hanspeter A.

2014-01-01

Space perception provides egocentric, oriented views of the environment from which working and long-term memories are constructed. “Allocentric” (i.e. position-independent) long-term memories may be organized as graphs of recognized places or views but the interaction of such cognitive graphs with egocentric working memories is unclear. Here we present a simple coherent model of view-based working and long-term memories, together with supporting evidence from behavioral experiments. The model predicts that within a given place, memories for some views may be more salient than others, that imagery of a target square should depend on the location where the recall takes place, and that recall favors views of the target square that would be obtained when approaching it from the current recall location. In two separate experiments in an outdoor urban environment, pedestrians were approached at various interview locations and asked to draw sketch maps of one of two well-known squares. Orientations of the sketch map productions depended significantly on distance and direction of the interview location from the target square, i.e. different views were recalled at different locations. Further analysis showed that location-dependent recall is related to the respective approach direction when imagining a walk from the interview location to the target square. The results are consistent with a view-based model of spatial long-term and working memories and their interplay. PMID:25409437

A spherical electron-channelling pattern map for use in quartz petrofabric analysis

USGS Publications Warehouse

Lloyd, G.E.; Ferguson, C.C.

1986-01-01

Electron channelling patterns (ECP's) are formed in the scanning electron microscope (SEM) by the interaction between the incident electrons and the lattice of crystalline specimens. The patterns are unique for a particular crystallographic orientation and are therefore of considerable potential in petrofabric studies provided they can be accurately indexed. Indexing requires an ECP-map of the crystallographic stereogram or unit triangle covering all possible orientations and hence ECP patterns. Due to the presence of long-range distortions in planar ECP-maps, it is more convenient to construct the maps over a spherical surface. This also facilitates the indexing of individual ECP's. A spherical ECP-map for quartz is presented together with an example of its use in petrofabric analysis. ?? 1986.

Characterization of fracture permeability with high-resolution vertical flow measurements during borehole pumping.

USGS Publications Warehouse

Paillet, Frederick L.; Hess, A.E.; Cheng, C.H.; Hardin, E.

1987-01-01

The distribution of fracture permeability in granitic rocks was investigated by measuring the distribution of vertical flow in boreholes during periods of steady pumping. Pumping tests were conducted at two sites chosen to provide examples of moderately fractured rocks near Mirror Lake, New Hampshire and intensely fractured rocks near Oracle, Arizona. A sensitive heat-pulse flowmeter was used for accurate measurements of vertical flow as low as 0.2 liter per minute. Results indicate zones of fracture permeability in crystalline rocks are composed of irregular conduits that cannot be approximated by planar fractures of uniform aperture, and that the orientation of permeability zones may be unrelated to the orientation of individual fractures within those zones.-Authors

Electro-optical tunable birefringent filter

DOEpatents

Levinton, Fred M [Princeton, NJ

2012-01-31

An electrically tunable Lyot type filter is a Lyot that include one or more filter elements. Each filter element may have a planar, solid crystal comprised of a material that exhibits birefringence and is electro-optically active. Transparent electrodes may be coated on each face of the crystal. An input linear light polarizer may be located on one side of the crystal and oriented at 45 degrees to the optical axis of the birefringent crystal. An output linear light polarizer may be located on the other side of the crystal and oriented at -45 degrees with respect to the optical axis of the birefringent crystal. When an electric voltage is applied between the electrodes, the retardation of the crystal changes and so does the spectral transmission of the optical filter.

Solid-state supramolecular structure of tetrakis(1-(diaminomethylene)thiouron-1-ium) pyromellate

NASA Astrophysics Data System (ADS)

Janczak, Jan

2018-03-01

The single crystals of tetrakis(1-(diaminomethylene)thiouron-1-ium) pyromellate suitable for the X-ray analysis were grown using a solution growth technique at room temperature. The compound crystallises in the centrosymmetric space group P21/c of the monoclinic system. Asymmetric unit consists of half of the tetrakis(1-(diaminomethylene)thiouron-1-ium) pyromellate molecule. Both independent parts of the 1-(diaminomethylene)-thiouron-1-ium cations are not strictly planar, but twisted. Both planar arms of the cation are oppositely rotated around the Csbnd N bonds involving the central N atom of the cation. The arrangement of the oppositely charged components, i.e. 1-(diaminomethylene)-thiouron-1-ium cations and pyromellate(4-) anion is determined by the Nsbnd H⋯O hydrogen bonds with R22(8) and R21(6) graphs forming supramolecular tetrakis(1-(diaminomethylene)-thiouron-1-ium) pyromellate units that further interact each other forming three dimensional hydrogen bonded network. Hirshfeld surface and the analysis of the 2D-fingerprint plots are illustrating both qualitatively and quantitatively interactions governing the formation of the supramolecular tetrakis(1-(diaminomethylene)-thiouron-1-ium) pyromellate complex as well as the mutual arrangement of the supramolecules in the crystal. The compound was also characterized by the FT-IR and Raman spectroscopy. Assignment of the bands have been supported by the isotropic frequency shift.

Measurements of orientation, sedimentation, and dispersal of ramified particles in isotropic turbulence

NASA Astrophysics Data System (ADS)

Voth, Greg A.; Kramel, Stefan; Menon, Udayshankar K.; Koch, Donald L.

2017-11-01

We experimentally measure the sedimentation of non-spherical particles in isotropic turbulence. We obtain time-resolved 3D orientations of the particles along with the fluid velocity field around them in a vertical water tunnel. An active jet array with 40 individually controllable jets enables us to adjust the turbulence intensity and observe the transition from strongly aligned to randomized particle orientations. We focus on the orientation statistics of ramified particles formed from several slender arms, including fibers and particles with three arms in planar symmetry (triads), which allows us to study alignment of both fibers and disk-like particles. We can predict the turbulent intensity at which the transition from aligned to randomized particle orientations occurs using a non-dimensional settling factor given by the ratio of rotation timescale of the turbulence at the scale of the particle to the rotation timescale of a particles in quiescent flow due to inertial torques. A model of ramified particle motion based on slender body theory provides accurate predictions of the vertical and horizontal particle velocities relative to the turbulent fluid. Supported by Army Research Office Grant W911NF1510205.

Boosting Photon Harvesting in Organic Solar Cells with Highly Oriented Molecular Crystals via Graphene-Organic Heterointerface.

PubMed

Jo, Sae Byeok; Kim, Hyun Ho; Lee, Hansol; Kang, Boseok; Lee, Seongkyu; Sim, Myungsun; Kim, Min; Lee, Wi Hyoung; Cho, Kilwon

2015-08-25

Photon harvesting in organic solar cells is highly dependent on the anisotropic nature of the optoelectronic properties of photoactive materials. Here, we demonstrate an efficient approach to dramatically enhance photon harvesting in planar heterojunction solar cells by using a graphene-organic heterointerface. A large area, residue-free monolayer graphene is inserted at anode interface to serve as an atomically thin epitaxial template for growing highly orientated pentacene crystals with lying-down orientation. This anisotropic orientation enhances the overall optoelectronic properties, including light absorption, charge carrier lifetime, interfacial energetics, and especially the exciton diffusion length. Spectroscopic and crystallographic analysis reveal that the lying-down orientation persists until a thickness of 110 nm, which, along with increased exciton diffusion length up to nearly 100 nm, allows the device optimum thickness to be doubled to yield significantly enhanced light absorption within the photoactive layers. The resultant photovoltaic performance shows simultaneous increment in Voc, Jsc, and FF, and consequently a 5 times increment in the maximum power conversion efficiency than the equivalent devices without a graphene layer. The present findings indicate that controlling organic-graphene heterointerface could provide a design strategy of organic solar cell architecture for boosting photon harvesting.

The Effect of Sn Orientation on Intermetallic Compound Growth in Idealized Sn-Cu-Ag Interconnects

NASA Astrophysics Data System (ADS)

Kinney, Chris; Linares, Xioranny; Lee, Kyu-Oh; Morris, J. W.

2013-04-01

The work reported here explores the influence of crystal orientation on the growth of the interfacial intermetallic layer during electromigration in Cu||Sn||Cu solder joints. The samples were thin, planar Sn-Ag-Cu (SAC) solder layers between Cu bars subject to a uniaxial current. Electron backscatter diffraction (EBSD) was used to characterize the microstructure before and after testing. The most useful representation of the EBSD data identifies the Sn grain orientation by the angle between the Sn c-axis and the current direction. The tested samples included single-crystal joints with c-axis nearly parallel to the current ("green" samples) and with c-axis perpendicular to the current ("red" samples). At current density of 104 A/cm2 (steady-state temperature of ~150°C), an intermetallic layer grew at an observable rate in the "green" samples, but not in the "red" ones. A current density of 1.15 × 104 A/cm2 (temperature ~160°C) led to measurable intermetallic growth in both samples. The growth fronts were nearly planar and the growth rates constant (after an initial incubation period); the growth rates in the "green" samples were about 10× those in the "red" samples. The Cu concentrations were constant within the joints, showing that the intermetallic growth is dominated by the electromigration flux. The measured growth rates and literature values for the diffusion of Cu in Sn were used to extract values for the effective charge, z *, that governs the electromigration of Cu. The calculated value of z * is significantly larger for current perpendicular to the c-axis than along it.

Slicken 1.0: Program for calculating the orientation of shear on reactivated faults

NASA Astrophysics Data System (ADS)

Xu, Hong; Xu, Shunshan; Nieto-Samaniego, Ángel F.; Alaniz-Álvarez, Susana A.

2017-07-01

The slip vector on a fault is an important parameter in the study of the movement history of a fault and its faulting mechanism. Although there exist many graphical programs to represent the shear stress (or slickenline) orientations on faults, programs to quantitatively calculate the orientation of fault slip based on a given stress field are scarce. In consequence, we develop Slicken 1.0, a software to rapidly calculate the orientation of maximum shear stress on any fault plane. For this direct method of calculating the resolved shear stress on a planar surface, the input data are the unit vector normal to the involved plane, the unit vectors of the three principal stress axes, and the stress ratio. The advantage of this program is that the vertical or horizontal principal stresses are not necessarily required. Due to its nimble design using Java SE 8.0, it runs on most operating systems with the corresponding Java VM. The software program will be practical for geoscience students, geologists and engineers and will help resolve a deficiency in field geology, and structural and engineering geology.

Unit-Sphere Anisotropic Multiaxial Stochastic-Strength Model Probability Density Distribution for the Orientation of Critical Flaws

NASA Technical Reports Server (NTRS)

Nemeth, Noel

2013-01-01

Models that predict the failure probability of monolithic glass and ceramic components under multiaxial loading have been developed by authors such as Batdorf, Evans, and Matsuo. These "unit-sphere" failure models assume that the strength-controlling flaws are randomly oriented, noninteracting planar microcracks of specified geometry but of variable size. This report develops a formulation to describe the probability density distribution of the orientation of critical strength-controlling flaws that results from an applied load. This distribution is a function of the multiaxial stress state, the shear sensitivity of the flaws, the Weibull modulus, and the strength anisotropy. Examples are provided showing the predicted response on the unit sphere for various stress states for isotropic and transversely isotropic (anisotropic) materials--including the most probable orientation of critical flaws for offset uniaxial loads with strength anisotropy. The author anticipates that this information could be used to determine anisotropic stiffness degradation or anisotropic damage evolution for individual brittle (or quasi-brittle) composite material constituents within finite element or micromechanics-based software

FOCUSR: Feature Oriented Correspondence using Spectral Regularization–A Method for Precise Surface Matching

PubMed Central

Lombaert, Herve; Grady, Leo; Polimeni, Jonathan R.; Cheriet, Farida

2013-01-01

Existing methods for surface matching are limited by the trade-off between precision and computational efficiency. Here we present an improved algorithm for dense vertex-to-vertex correspondence that uses direct matching of features defined on a surface and improves it by using spectral correspondence as a regularization. This algorithm has the speed of both feature matching and spectral matching while exhibiting greatly improved precision (distance errors of 1.4%). The method, FOCUSR, incorporates implicitly such additional features to calculate the correspondence and relies on the smoothness of the lowest-frequency harmonics of a graph Laplacian to spatially regularize the features. In its simplest form, FOCUSR is an improved spectral correspondence method that nonrigidly deforms spectral embeddings. We provide here a full realization of spectral correspondence where virtually any feature can be used as additional information using weights on graph edges, but also on graph nodes and as extra embedded coordinates. As an example, the full power of FOCUSR is demonstrated in a real case scenario with the challenging task of brain surface matching across several individuals. Our results show that combining features and regularizing them in a spectral embedding greatly improves the matching precision (to a sub-millimeter level) while performing at much greater speed than existing methods. PMID:23868776

Oriented thin films of mixture of a low-bandgap polymer and a fullerene derivative prepared by friction-transfer method

NASA Astrophysics Data System (ADS)

Tanigaki, Nobutaka; Mizokuro, Toshiko; Miyadera, Tetsuhiko; Shibata, Yousei; Koganezawa, Tomoyuki

2018-02-01

We have been studying oriented thin films of polymers fabricated by the friction-transfer method, which allows the alignment of a variety of conjugated polymers into highly oriented films. In this study, we prepared oriented blend films of a mixture of a low-bandgap polymer, poly{4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b‧]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7), and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), which is a promising combination for application in organic solar cells. We obtained oriented blend films of PTB7 and PC71BM by the friction-transfer method from a solid block. Polarized UV-visible spectra show that the PTB7 chains were aligned parallel to the friction direction in the blend films. Grazing-incidence X-ray diffraction (GIXD) studies with synchrotron radiation suggested that the preferred orientation of PTB7 crystallites was face-on in the blend films. The GIXD results also showed the high uniaxial orientation of PTB7 chains in blend films. Photovoltaic devices were fabricated using the friction-transferred blend films of the PTB7 and PC71BM. These bulk heterojunction devices showed better performance than planar heterojunction devices fabricated using pure friction-transferred PTB7 films.

BRAPH: A graph theory software for the analysis of brain connectivity

PubMed Central

Mijalkov, Mite; Kakaei, Ehsan; Pereira, Joana B.; Westman, Eric; Volpe, Giovanni

2017-01-01

The brain is a large-scale complex network whose workings rely on the interaction between its various regions. In the past few years, the organization of the human brain network has been studied extensively using concepts from graph theory, where the brain is represented as a set of nodes connected by edges. This representation of the brain as a connectome can be used to assess important measures that reflect its topological architecture. We have developed a freeware MatLab-based software (BRAPH–BRain Analysis using graPH theory) for connectivity analysis of brain networks derived from structural magnetic resonance imaging (MRI), functional MRI (fMRI), positron emission tomography (PET) and electroencephalogram (EEG) data. BRAPH allows building connectivity matrices, calculating global and local network measures, performing non-parametric permutations for group comparisons, assessing the modules in the network, and comparing the results to random networks. By contrast to other toolboxes, it allows performing longitudinal comparisons of the same patients across different points in time. Furthermore, even though a user-friendly interface is provided, the architecture of the program is modular (object-oriented) so that it can be easily expanded and customized. To demonstrate the abilities of BRAPH, we performed structural and functional graph theory analyses in two separate studies. In the first study, using MRI data, we assessed the differences in global and nodal network topology in healthy controls, patients with amnestic mild cognitive impairment, and patients with Alzheimer’s disease. In the second study, using resting-state fMRI data, we compared healthy controls and Parkinson’s patients with mild cognitive impairment. PMID:28763447

BRAPH: A graph theory software for the analysis of brain connectivity.

PubMed

Mijalkov, Mite; Kakaei, Ehsan; Pereira, Joana B; Westman, Eric; Volpe, Giovanni

2017-01-01

The brain is a large-scale complex network whose workings rely on the interaction between its various regions. In the past few years, the organization of the human brain network has been studied extensively using concepts from graph theory, where the brain is represented as a set of nodes connected by edges. This representation of the brain as a connectome can be used to assess important measures that reflect its topological architecture. We have developed a freeware MatLab-based software (BRAPH-BRain Analysis using graPH theory) for connectivity analysis of brain networks derived from structural magnetic resonance imaging (MRI), functional MRI (fMRI), positron emission tomography (PET) and electroencephalogram (EEG) data. BRAPH allows building connectivity matrices, calculating global and local network measures, performing non-parametric permutations for group comparisons, assessing the modules in the network, and comparing the results to random networks. By contrast to other toolboxes, it allows performing longitudinal comparisons of the same patients across different points in time. Furthermore, even though a user-friendly interface is provided, the architecture of the program is modular (object-oriented) so that it can be easily expanded and customized. To demonstrate the abilities of BRAPH, we performed structural and functional graph theory analyses in two separate studies. In the first study, using MRI data, we assessed the differences in global and nodal network topology in healthy controls, patients with amnestic mild cognitive impairment, and patients with Alzheimer's disease. In the second study, using resting-state fMRI data, we compared healthy controls and Parkinson's patients with mild cognitive impairment.

Attachment of second harmonic-active moiety to molecules for detection of molecules at interfaces

DOEpatents

Salafsky, Joshua S.; Eisenthal, Kenneth B.

2005-10-11

This invention provides methods of detecting molecules at an interface, which comprise labeling the molecules with a second harmonic-active moiety and detecting the labeled molecules at the interface using a surface selective technique. The invention also provides methods for detecting a molecule in a medium and for determining the orientation of a molecular species within a planar surface using a second harmonic-active moiety and a surface selective technique.

Charge line quad pulser

DOEpatents

Booth, R.

1996-10-08

A quartet of parallel coupled planar triodes is removably mounted in a quadrahedron shaped PCB structure. Releasable brackets and flexible means attached to each triode socket make triode cathode and grid contact with respective conductive coatings on the PCB and a detachable cylindrical conductive element enclosing and contacting the triode anodes jointly permit quick and easy replacement of faulty triodes. By such orientation, the quad pulser can convert a relatively low and broad pulse into a very high and narrow pulse. 16 figs.

Charge line quad pulser

DOEpatents

Booth, Rex

1996-01-01

A quartet of parallel coupled planar triodes is removably mounted in a quadrahedron shaped PCB structure. Releasable brackets and flexible means attached to each triode socket make triode cathode and grid contact with respective conductive coatings on the PCB and a detachable cylindrical conductive element enclosing and contacting the triode anodes jointly permit quick and easy replacement of faulty triodes. By such orientation, the quad pulser can convert a relatively low and broad pulse into a very high and narrow pulse.

Apparatus and methods for filtering granular solid material

NASA Technical Reports Server (NTRS)

Backes, Douglas J. (Inventor); Poulter, Clay B. (Inventor); Godfrey, Max R. (Inventor); Tolman, Dennis K. (Inventor); Dutton, Melinda S. (Inventor)

2011-01-01

Apparatuses for screening granular solid particulate material include a generally planar first screen and a second screen. A plurality of apertures extends through the first screen. At least a portion of the second screen is oriented at an angle to the first screen, and apertures extend through a perforated region of the second screen. The second screen includes at least one region configured to prevent at least some particles of solid material from passing through the second screen.

Solar thermal collectors using planar reflector

NASA Technical Reports Server (NTRS)

Espy, P. N.

1978-01-01

Specular reflectors have been used successfully with flat-plate collectors to achieve exceptionally high operating temperatures and high delivered energy per unit collector area. Optimal orientation of collectors and reflectors can result in even higher performance with an improved relationship between energy demand and supply. This paper reports on a study providing first order optimization of collector-reflector arrays in which single- and multiple-faceted reflectors in fixed or singly adjustable configurations provide delivered energy maxima in either summer or winter.

3D structural patterns in scalable, elastomeric scaffolds guide engineered tissue architecture.

PubMed

Kolewe, Martin E; Park, Hyoungshin; Gray, Caprice; Ye, Xiaofeng; Langer, Robert; Freed, Lisa E

2013-08-27

Microfabricated elastomeric scaffolds with 3D structural patterns are created by semiautomated layer-by-layer assembly of planar polymer sheets with through-pores. The mesoscale interconnected pore architectures governed by the relative alignment of layers are shown to direct cell and muscle-like fiber orientation in both skeletal and cardiac muscle, enabling scale up of tissue constructs towards clinically relevant dimensions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication and characterization of 3C-silicon carbide micro sensor for wireless blood pressure measurements

NASA Astrophysics Data System (ADS)

Basak, Nupur

A potentially implantable single crystal 3C-SiC pressure sensor for blood pressure measurement was designed, simulated, fabricated, characterized and optimized. This research uses a single crystal 3C-SiC, for the first time, to demonstrate its application as a blood pressure measurement sensor. The sensor, which uses the epitaxial grown 3C-SiC membrane to measure changes in pressure, is designed to be wireless, biocompatible and linear. The SiC material was chosen for its superior physical, chemical and mechanical properties; the capacitive sensor uses a 3C-SiC membrane as one of the electrodes; and, the sensor system is wireless for comfort and to allow for convenient reading of real-time pressure data (wireless communication is enabled by connecting the sensor parallel to a planar inductor). Together, the variable capacitive sensor and planar inductor create a pressure sensitive resonant circuit. The sensor system described above allows for implantation into a human patient's body, after which the planar inductor can be coupled with an external inductor to receive data for real-time blood pressure measurement. Electroplating, thick photo-resist characterization, RIE etching, oxidation, CVD, chemical mechanical polishing and wafer bonding were optimized during the process of fabricating the sensor system and, in addition to detailing the sensor system simulation and characterization; the optimized processes are detailed in the dissertation. This absolute pressure sensor is designed to function optimally within the human blood pressure range of 50-350mmHg. The layout and modeling of the sensor uses finite element analysis (FEA) software. The simulations for membrane deflection, stress analysis and electro-mechanical analysis are performed for 100 μm2 and 400μm2sensors. The membrane deflection-pressure, capacitance-pressure and resonant frequency-pressure graphs were obtained, and detailed in the dissertation, along with the planar inductor simulation for differently sized inductors. Ultimately, an optimized sensor with a size of 400μm2 was chosen because of its high sensitivity. The sensor, and the planar inductor, which is 3mm 2, is comparable to the presently researched implantable chip size. The measured inductance of the gold electroplated inductor is 0.371μH. The capacitance changes from 0.934 pF to 0.997pF with frequency shift of 248MHz to 256 MHz. The sensitivity of the sensor is found to be 0.21 fF/mmHg or 27.462 kHz/mmHg with an average non-linearity of 0.23216%.

Automatic correction of echo-planar imaging (EPI) ghosting artifacts in real-time interactive cardiac MRI using sensitivity encoding.

PubMed

Kim, Yoon-Chul; Nielsen, Jon-Fredrik; Nayak, Krishna S

2008-01-01

To develop a method that automatically corrects ghosting artifacts due to echo-misalignment in interleaved gradient-echo echo-planar imaging (EPI) in arbitrary oblique or double-oblique scan planes. An automatic ghosting correction technique was developed based on an alternating EPI acquisition and the phased-array ghost elimination (PAGE) reconstruction method. The direction of k-space traversal is alternated at every temporal frame, enabling lower temporal-resolution ghost-free coil sensitivity maps to be dynamically estimated. The proposed method was compared with conventional one-dimensional (1D) phase correction in axial, oblique, and double-oblique scan planes in phantom and cardiac in vivo studies. The proposed method was also used in conjunction with two-fold acceleration. The proposed method with nonaccelerated acquisition provided excellent suppression of ghosting artifacts in all scan planes, and was substantially more effective than conventional 1D phase correction in oblique and double-oblique scan planes. The feasibility of real-time reconstruction using the proposed technique was demonstrated in a scan protocol with 3.1-mm spatial and 60-msec temporal resolution. The proposed technique with nonaccelerated acquisition provides excellent ghost suppression in arbitrary scan orientations without a calibration scan, and can be useful for real-time interactive imaging, in which scan planes are frequently changed with arbitrary oblique orientations.

Geometry can provide long-range mechanical guidance for embryogenesis

PubMed Central

Dicko, Mahamar; Saramito, Pierre

2017-01-01

Downstream of gene expression, effectors such as the actomyosin contractile machinery drive embryo morphogenesis. During Drosophila embryonic axis extension, actomyosin has a specific planar-polarised organisation, which is responsible for oriented cell intercalation. In addition to these cell rearrangements, cell shape changes also contribute to tissue deformation. While cell-autonomous dynamics are well described, understanding the tissue-scale behaviour challenges us to solve the corresponding mechanical problem at the scale of the whole embryo, since mechanical resistance of all neighbouring epithelia will feedback on individual cells. Here we propose a novel numerical approach to compute the whole-embryo dynamics of the actomyosin-rich apical epithelial surface. We input in the model specific patterns of actomyosin contractility, such as the planar-polarisation of actomyosin in defined ventro-lateral regions of the embryo. Tissue strain rates and displacements are then predicted over the whole embryo surface according to the global balance of stresses and the material behaviour of the epithelium. Epithelia are modelled using a rheological law that relates the rate of deformation to the local stresses and actomyosin anisotropic contractility. Predicted flow patterns are consistent with the cell flows observed when imaging Drosophila axis extension in toto, using light sheet microscopy. The agreement between model and experimental data indicates that the anisotropic contractility of planar-polarised actomyosin in the ventro-lateral germband tissue can directly cause the tissue-scale deformations of the whole embryo. The three-dimensional mechanical balance is dependent on the geometry of the embryo, whose curved surface is taken into account in the simulations. Importantly, we find that to reproduce experimental flows, the model requires the presence of the cephalic furrow, a fold located anteriorly of the extending tissues. The presence of this geometric feature, through the global mechanical balance, guides the flow and orients extension towards the posterior end. PMID:28346461

Dextrous robot hands

NASA Technical Reports Server (NTRS)

Venkataraman, Subramanian T. (Editor); Iberall, Thea (Editor)

1990-01-01

Recent studies of human hand function and their implications for the design of robot hands are discussed in reviews and reports. Topics addressed include human grasp choice and robotic grasp analysis, opposition space and human prehension, coordination in normal and prosthetic reaching, and intelligent exploration by the human hand. Consideration is given to a task-oriented dextrous manipulation architecture, the control architecture for the Belgrade/USC hand, the analysis of multifingered grasping and manipulation, and tactile sensing for shape interpretation. Diagrams, graphs, and photographs are provided.

North American Jumelage ’Type Systems’

DTIC Science & Technology

1993-10-20

Brian Howard bhoward~saul.cis.upenn.edu Doug Howe howegcs.cornell.edu Paul Jackson jacksongcs.cornell.edu Radhakrishnan Jagadeesan rj2Gdoc.imperial.ac.uk...Curry and Howard . They have shown that there exists an ’’isomorphism’’ between the terms of typed lambda calculus and the natural deduction proofs of...linear logic for computer science 3:05-3:30 Break 3:30-4:00 G. Bellin , Oxford University: Proof-nets without boxes and graphs with orientations 4:05-4:25 H

A Meta System for Generating Software Engineering Environments.

DTIC Science & Technology

1985-01-01

CI/NR-85-710 UNCLSSIFIED F/ G 9/2 NL 1.0 2-8! j~j~ 1s 3-15 jjll !2 __ L__ ILlh 1121 ,.., - - NATIONAL BUREAU OF STANDARDS MSCRCOPY RESOLUMIN TEST CHART...34 ". " ....-.... .......-... . . - ...-............’. . -...... -.--..-..-.. : 23 H4eta Dt: t-o (Knowled&e Base) Attributed G raoonr form ___ lepresenta tion of a Kethod...implements a programming environment on a relational database. The IDEOSY system 38’ is a graph-oriented language programming environment. I l t . G = o

An object-oriented approach to data display and storage: 3 years experience, 25,000 cases.

PubMed

Sainsbury, D A

1993-11-01

Object-oriented programming techniques were used to develop computer based data display and storage systems. These have been operating in the 8 anaesthetising areas of the Adelaide Children's Hospital for 3 years. The analogue and serial outputs from an array of patient monitors are connected to IBM compatible PC-XT computers. The information is displayed on a colour screen as wave-form and trend graphs and digital format in 'real time'. The trend data is printed simultaneously on a dot matrix printer. This data is also stored for 24 hours on 'hard' disk. The major benefit has been the provision of a single visual focus for all monitored variables. The automatic logging of data has been invaluable in the analysis of critical incidents. The systems were made possible by recent, rapid improvements in computer hardware and software. This paper traces the development of the program and demonstrates the advantages of object-oriented programming techniques.

All-dielectric planar chiral metasurface with gradient geometric phase.

PubMed

Ma, Zhijie; Li, Yi; Li, Yang; Gong, Yandong; Maier, Stefan A; Hong, Minghui

2018-03-05

Planar optical chirality of a metasurface measures its differential response between left and right circularly polarized (CP) lights and governs the asymmetric transmission of CP lights. In 2D ultra-thin plasmonic structures the circular dichroism is limited to 25% in theory and it requires high absorption loss. Here we propose and numerically demonstrate a planar chiral all-dielectric metasurface that exhibits giant circular dichroism and transmission asymmetry over 0.8 for circularly polarized lights with negligible loss, without bringing in bianisotropy or violating reciprocity. The metasurface consists of arrays of high refractive index germanium Z-shape resonators that break the in-plane mirror symmetry and induce cross-polarization conversion. Furthermore, at the transmission peak of one handedness, the transmitted light is efficiently converted into the opposite circular polarization state, with a designated geometric phase depending on the orientation angle of the optical element. In this way, the optical component sets before and after the metasurface to filter the light of certain circular polarization states are not needed and the metasurface can function under any linear polarization, in contrast to the conventional setup for geometry phase based metasurfaces. Anomalous transmission and two-dimensional holography based on the geometric phase chiral metasurface are numerically demonstrate as proofs of concept.

Registration of immunoglobuline AB/AG reaction with planar polarization interferometer

NASA Astrophysics Data System (ADS)

Nabok, Alexei V.; Starodub, Nickolaj F.; Ray, Asim K.; Hassan, Aseel K.

2000-12-01

Immobilization of human immunoglobuline (IgG) (AG) and goat on human IGG antibodies (AB) as well as AB/AG specific reaction were studied with planar polarization interferometry (PPI). In this novel method, polarized laser beam was coupled into the planar waveguide made on silicon wafer and consisted of 20nm Si3N4 layer sandwiched between two 1.5 micrometers SiO2 layers with the sensing window etched in the top SIO2 layer. One of the immune components was deposited by means of polyelectrolyte self- assembly on top of the Si3N3 layer within the sensing window, P-component of the polarized light is sensitive to adsorption, while s-component serves as a reference. Thus the outcoming light intensity depends on the phase shift between s- and p-components. Different sequences of immobilization of the immune components were studied with both surface plasmon resonance (SPR) and PPI methods. It was shown that predeposition of a monolayer of protein A, which is believed to affect the orientation of the immune components, causes an additional increase in the sensitivity. PPI method allowed us to improve substantially the sensitivity towards AB/AG reaction as compared to traditional SPR method. Particularly, of specific binding of 3ng/ml AG was registered.

Isotropic enhancement in the critical current density of YBCO thin films incorporating nanoscale Y2BaCuO5 inclusions

NASA Astrophysics Data System (ADS)

Jha, Alok K.; Matsumoto, Kaname; Horide, Tomoya; Saini, Shrikant; Mele, Paolo; Ichinose, Ataru; Yoshida, Yutaka; Awaji, Satoshi

2017-09-01

The effect of incorporation of nanoscale Y2BaCuO5 (Y211) inclusions on the vortex pinning properties of YBa2Cu3O7-δ (YBCO or Y123) superconducting thin films is investigated in detail on the basis of variation of critical current density (JC) with applied magnetic field and also with the orientation of the applied magnetic field at two different temperatures: 77 K and 65 K. Surface modified target approach is employed to incorporate nanoscale Y211 inclusions into the superconducting YBCO matrix. The efficiency of Y211 nanoinclusions in reducing the angular anisotropy of critical current density is found to be significant. The observed angular dependence of the critical current density is discussed on the basis of mutually occupied volume by a vortex and spherical and/or planar defect. A dip in JC near the ab-plane is also observed which has been analyzed on the basis of variation of pinning potential corresponding to a spherical (3-D) or planar (2-D) pinning center and has been attributed to a reduced interaction volume of the vortices with a pinning center and competing nature of the potentials due to spherical and planar defects.

Genetic analysis of ectopic growth suppression during planar growth of integuments mediated by the Arabidopsis AGC protein kinase UNICORN

PubMed Central

2013-01-01

Background The coordination of growth within a tissue layer is of critical importance for tissue morphogenesis. For example, cells within the epidermis undergo stereotypic cell divisions that are oriented along the plane of the layer (planar growth), thereby propagating the layered epidermal structure. Little is known about the developmental control that regulates such planar growth in plants. Recent evidence suggested that the Arabidopsis AGC VIII protein kinase UNICORN (UCN) maintains planar growth by suppressing the formation of ectopic multicellular protrusions in several floral tissues including integuments. In the current model UCN controls this process during integument development by directly interacting with the ABERRANT TESTA SHAPE (ATS) protein, a member of the KANADI (KAN) family of transcription factors, thereby repressing its activity. Here we report on the further characterization of the UCN mechanism. Results Phenotypic analysis of flowers of ucn-1 plants impaired in floral homeotic gene activity revealed that any of the four floral whorls could produce organs carrying ucn-1 protrusions. The ectopic outgrowths of ucn integuments did not accumulate detectable signals of the auxin and cytokinin reporters DR5rev::GFP and ARR5::GUS, respectively. Furthermore, wild-type and ucn-1 seedlings showed similarly strong callus formation upon in vitro culture on callus-inducing medium. We also show that ovules of ucn-1 plants carrying the dominant ats allele sk21-D exhibited more pronounced protrusion formation. Finally ovules of ucn-1 ett-1 double mutants and ucn-1 ett-1 arf4-1 triple mutants displayed an additive phenotype. Conclusions These data deepen the molecular insight into the UCN-mediated control of planar growth during integument development. The presented evidence indicates that UCN downstream signaling does not involve the control of auxin or cytokinin homeostasis. The results also reveal that UCN interacts with ATS independently of an ATS/ETT complex required for integument initiation and they further emphasize the necessity to balance UCN and ATS proteins during maintenance of planar growth in integuments. PMID:23281875

Automatic Camera Calibration for Cultural Heritage Applications Using Unstructured Planar Objects

NASA Astrophysics Data System (ADS)

Adam, K.; Kalisperakis, I.; Grammatikopoulos, L.; Karras, G.; Petsa, E.

2013-07-01

As a rule, image-based documentation of cultural heritage relies today on ordinary digital cameras and commercial software. As such projects often involve researchers not familiar with photogrammetry, the question of camera calibration is important. Freely available open-source user-friendly software for automatic camera calibration, often based on simple 2D chess-board patterns, are an answer to the demand for simplicity and automation. However, such tools cannot respond to all requirements met in cultural heritage conservation regarding possible imaging distances and focal lengths. Here we investigate the practical possibility of camera calibration from unknown planar objects, i.e. any planar surface with adequate texture; we have focused on the example of urban walls covered with graffiti. Images are connected pair-wise with inter-image homographies, which are estimated automatically through a RANSAC-based approach after extracting and matching interest points with the SIFT operator. All valid points are identified on all images on which they appear. Provided that the image set includes a "fronto-parallel" view, inter-image homographies with this image are regarded as emulations of image-to-world homographies and allow computing initial estimates for the interior and exterior orientation elements. Following this initialization step, the estimates are introduced into a final self-calibrating bundle adjustment. Measures are taken to discard unsuitable images and verify object planarity. Results from practical experimentation indicate that this method may produce satisfactory results. The authors intend to incorporate the described approach into their freely available user-friendly software tool, which relies on chess-boards, to assist non-experts in their projects with image-based approaches.

Spread of risk across financial markets: better to invest in the peripheries

NASA Astrophysics Data System (ADS)

Pozzi, F.; Di Matteo, T.; Aste, T.

2013-04-01

Risk is not uniformly spread across financial markets and this fact can be exploited to reduce investment risk contributing to improve global financial stability. We discuss how, by extracting the dependency structure of financial equities, a network approach can be used to build a well-diversified portfolio that effectively reduces investment risk. We find that investments in stocks that occupy peripheral, poorly connected regions in financial filtered networks, namely Minimum Spanning Trees and Planar Maximally Filtered Graphs, are most successful in diversifying, improving the ratio between returns' average and standard deviation, reducing the likelihood of negative returns, while keeping profits in line with the general market average even for small baskets of stocks. On the contrary, investments in subsets of central, highly connected stocks are characterized by greater risk and worse performance. This methodology has the added advantage of visualizing portfolio choices directly over the graphic layout of the network.

Spread of risk across financial markets: better to invest in the peripheries

PubMed Central

Pozzi, F.; Di Matteo, T.; Aste, T.

2013-01-01

Risk is not uniformly spread across financial markets and this fact can be exploited to reduce investment risk contributing to improve global financial stability. We discuss how, by extracting the dependency structure of financial equities, a network approach can be used to build a well-diversified portfolio that effectively reduces investment risk. We find that investments in stocks that occupy peripheral, poorly connected regions in financial filtered networks, namely Minimum Spanning Trees and Planar Maximally Filtered Graphs, are most successful in diversifying, improving the ratio between returns' average and standard deviation, reducing the likelihood of negative returns, while keeping profits in line with the general market average even for small baskets of stocks. On the contrary, investments in subsets of central, highly connected stocks are characterized by greater risk and worse performance. This methodology has the added advantage of visualizing portfolio choices directly over the graphic layout of the network. PMID:23588852

Simulation of spread and control of lesions in brain.

PubMed

Thamattoor Raman, Krishna Mohan

2012-01-01

A simulation model for the spread and control of lesions in the brain is constructed using a planar network (graph) representation for the central nervous system (CNS). The model is inspired by the lesion structures observed in the case of multiple sclerosis (MS), a chronic disease of the CNS. The initial lesion site is at the center of a unit square and spreads outwards based on the success rate in damaging edges (axons) of the network. The damaged edges send out alarm signals which, at appropriate intensity levels, generate programmed cell death. Depending on the extent and timing of the programmed cell death, the lesion may get controlled or aggravated akin to the control of wild fires by burning of peripheral vegetation. The parameter phase space of the model shows smooth transition from uncontrolled situation to controlled situation. The simulations show that the model is capable of generating a wide variety of lesion growth and arrest scenarios.

The study of Thai stock market across the 2008 financial crisis

NASA Astrophysics Data System (ADS)

Kanjamapornkul, K.; Pinčák, Richard; Bartoš, Erik

2016-11-01

The cohomology theory for financial market can allow us to deform Kolmogorov space of time series data over time period with the explicit definition of eight market states in grand unified theory. The anti-de Sitter space induced from a coupling behavior field among traders in case of a financial market crash acts like gravitational field in financial market spacetime. Under this hybrid mathematical superstructure, we redefine a behavior matrix by using Pauli matrix and modified Wilson loop for time series data. We use it to detect the 2008 financial market crash by using a degree of cohomology group of sphere over tensor field in correlation matrix over all possible dominated stocks underlying Thai SET50 Index Futures. The empirical analysis of financial tensor network was performed with the help of empirical mode decomposition and intrinsic time scale decomposition of correlation matrix and the calculation of closeness centrality of planar graph.

NET: a new framework for the vectorization and examination of network data.

PubMed

Lasser, Jana; Katifori, Eleni

2017-01-01

The analysis of complex networks both in general and in particular as pertaining to real biological systems has been the focus of intense scientific attention in the past and present. In this paper we introduce two tools that provide fast and efficient means for the processing and quantification of biological networks like Drosophila tracheoles or leaf venation patterns: the Network Extraction Tool ( NET ) to extract data and the Graph-edit-GUI ( GeGUI ) to visualize and modify networks. NET is especially designed for high-throughput semi-automated analysis of biological datasets containing digital images of networks. The framework starts with the segmentation of the image and then proceeds to vectorization using methodologies from optical character recognition. After a series of steps to clean and improve the quality of the extracted data the framework produces a graph in which the network is represented only by its nodes and neighborhood-relations. The final output contains information about the adjacency matrix of the graph, the width of the edges and the positions of the nodes in space. NET also provides tools for statistical analysis of the network properties, such as the number of nodes or total network length. Other, more complex metrics can be calculated by importing the vectorized network to specialized network analysis packages. GeGUI is designed to facilitate manual correction of non-planar networks as these may contain artifacts or spurious junctions due to branches crossing each other. It is tailored for but not limited to the processing of networks from microscopy images of Drosophila tracheoles. The networks extracted by NET closely approximate the network depicted in the original image. NET is fast, yields reproducible results and is able to capture the full geometry of the network, including curved branches. Additionally GeGUI allows easy handling and visualization of the networks.

Confinement and Ordering of Au Nanorods in Polymer Films

NASA Astrophysics Data System (ADS)

Hore, Michael J. A.; Mills, Eric; Liu, Yu; Composto, Russell J.

2009-03-01

Ordered arrays of gold nanorods (Au NRs) possess interesting optical properties that might be utilized in future devices. Au NRs functionalized with a poly(ethylene glycol)-thiol brush are incorporated into homopolymer or block copolymer (BCP) films. NR distribution and orientational correlations are studied as a function of nanorod concentration and spacial confinement via Rutherford backscattering spectrometry (RBS) and transmission electron microscopy, respectively. In particular, differences in the degree of nanorod ordering are presented for PMMA homopolymer films (d ˜ 45 nm) versus PS-b-PMMA BCP films (L/2 ˜ 40 nm), where higher ordering is seen in the case of BCP films. At moderate volume fractions of NRs, φ = 1% to 10%, the degree of ordering is moderate, and increases with increasing φ . However, coexistence between regions of higher ordering and isotropic orientations is observed. In addition to the planar confinement considered above, orientation of Au NRs confined to cylindrical P2VP domains is studied in PS-b-P2VP BCP films.

Controlling BaZrO3 nanostructure orientation in YBa2Cu3O{}_{7-\\delta } films for a three-dimensional pinning landscape

NASA Astrophysics Data System (ADS)

Wu, J. Z.; Shi, J. J.; Baca, F. J.; Emergo, R.; Wilt, J.; Haugan, T. J.

2015-12-01

The orientation phase diagram of self-assembled BaZrO3 (BZO) nanostructures in c-oriented YBa2Cu3O{}7-δ (YBCO) films on flat and vicinal SrTiO3 substrates was studied experimentally with different dopant concentrations and vicinal angles and theoretically using a micromechanical model based on the theory of elasticity. The organized BZO nanostructure configuration was found to be tunable, between c-axis to ab-plane alignment, by the dopant concentration in the YBCO film matrix strained via lattice mismatched substrates. The correlation between the local strain caused by the BZO doping and the global strain on the matrix provides a unique approach for controllable growth of dopant nanostructure landscapes. In particular, a mixed phase of the c-axis-aligned nanorods and the ab-plane-aligned planar nanostructures can be obtained, leading to a three-dimensional pinning landscape with single impurity doping and much improved J c in almost all directions of applied magnetic field.

4-Nitro­benzyl 2-bromo­acetate

PubMed Central

Zhu, Kai; Liu, Hui; Wang, Yan-Hua; Han, Ping-Fang; Wei, Ping

2009-01-01

In the mol­ecule of the title compound, C9H8BrNO4, the acetate group is close to planar [maximum deviation = 0.042 (3) Å] and is oriented at a dihedral angle of 73.24 (3)° with respect to the aromatic ring. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules into a three-dimensional network, forming R 2 2(10) ring motifs. PMID:21582813

Investigation of a Hybrid Wafer Scale Integration Technique that Mounts Discrete Integrated Circuit Die in a Silicon Substrate.

DTIC Science & Technology

1988-03-01

Polyimides as Planarizing and Insulative Coatings 2-21 III. Experimental Procedure, Equipment, and Materials 3-1 Wet Orientation Dependent Etching Study 3...1 Die Bond Adhesives Study .3-7 Fabrication of Samples for Electrical Testing 3-21 Evaluation of the Final Samples 3-45 IV. Experimental Results and...Discussion .. 4-1 We :ientation Dependent Etching Study Results 4-1 Die Attach Adhesives Study Results 4-21 Fabrication of Samples for Electrical

3-(2,4-Dichloro­anilino)iso­benzo­furan-1(3H)-one1

PubMed Central

Odabaşoğlu, Mustafa; Büyükgüngör, Orhan

2008-01-01

In the mol­ecule of the title compound, C14H9Cl2NO2, the essentially planar phthalide group is oriented at a dihedral angle of 63.23 (5)° with respect to the substituted aromatic ring. In the crystal structure, inter­molecular C—H⋯O and N—H⋯O hydrogen bonds link the mol­ecules, generating R 4 4(21) ring motifs to form a three-dimensional network. PMID:21202144

Reaction Mechanism Generator: Automatic construction of chemical kinetic mechanisms

NASA Astrophysics Data System (ADS)

Gao, Connie W.; Allen, Joshua W.; Green, William H.; West, Richard H.

2016-06-01

Reaction Mechanism Generator (RMG) constructs kinetic models composed of elementary chemical reaction steps using a general understanding of how molecules react. Species thermochemistry is estimated through Benson group additivity and reaction rate coefficients are estimated using a database of known rate rules and reaction templates. At its core, RMG relies on two fundamental data structures: graphs and trees. Graphs are used to represent chemical structures, and trees are used to represent thermodynamic and kinetic data. Models are generated using a rate-based algorithm which excludes species from the model based on reaction fluxes. RMG can generate reaction mechanisms for species involving carbon, hydrogen, oxygen, sulfur, and nitrogen. It also has capabilities for estimating transport and solvation properties, and it automatically computes pressure-dependent rate coefficients and identifies chemically-activated reaction paths. RMG is an object-oriented program written in Python, which provides a stable, robust programming architecture for developing an extensible and modular code base with a large suite of unit tests. Computationally intensive functions are cythonized for speed improvements.

Study on probability distributions for evolution in modified extremal optimization

NASA Astrophysics Data System (ADS)

Zeng, Guo-Qiang; Lu, Yong-Zai; Mao, Wei-Jie; Chu, Jian

2010-05-01

It is widely believed that the power-law is a proper probability distribution being effectively applied for evolution in τ-EO (extremal optimization), a general-purpose stochastic local-search approach inspired by self-organized criticality, and its applications in some NP-hard problems, e.g., graph partitioning, graph coloring, spin glass, etc. In this study, we discover that the exponential distributions or hybrid ones (e.g., power-laws with exponential cutoff) being popularly used in the research of network sciences may replace the original power-laws in a modified τ-EO method called self-organized algorithm (SOA), and provide better performances than other statistical physics oriented methods, such as simulated annealing, τ-EO and SOA etc., from the experimental results on random Euclidean traveling salesman problems (TSP) and non-uniform instances. From the perspective of optimization, our results appear to demonstrate that the power-law is not the only proper probability distribution for evolution in EO-similar methods at least for TSP, the exponential and hybrid distributions may be other choices.

Contingency Planning for Planetary Rovers

NASA Technical Reports Server (NTRS)

Dearden, Richard; Meuleau, Nicolas; Ramakrishnan, Sailesh; Smith, David; Washington, Rich; Clancy, Daniel (Technical Monitor)

2002-01-01

There has been considerable work in AI on planning under uncertainty. But this work generally assumes an extremely simple model of action that does not consider continuous time and resources. These assumptions are not reasonable for a Mars rover, which must cope with uncertainty about the duration of tasks, the power required, the data storage necessary, along with its position and orientation. In this paper, we outline an approach to generating contingency plans when the sources of uncertainty involve continuous quantities such as time and resources. The approach involves first constructing a "seed" plan, and then incrementally adding contingent branches to this plan in order to improve utility. The challenge is to figure out the best places to insert contingency branches. This requires an estimate of how much utility could be gained by building a contingent branch at any given place in the seed plan. Computing this utility exactly is intractable, but we outline an approximation method that back propagates utility distributions through a graph structure similar to that of a plan graph.

Incremental Contingency Planning

NASA Technical Reports Server (NTRS)

Dearden, Richard; Meuleau, Nicolas; Ramakrishnan, Sailesh; Smith, David E.; Washington, Rich

2003-01-01

There has been considerable work in AI on planning under uncertainty. However, this work generally assumes an extremely simple model of action that does not consider continuous time and resources. These assumptions are not reasonable for a Mars rover, which must cope with uncertainty about the duration of tasks, the energy required, the data storage necessary, and its current position and orientation. In this paper, we outline an approach to generating contingency plans when the sources of uncertainty involve continuous quantities such as time and resources. The approach involves first constructing a "seed" plan, and then incrementally adding contingent branches to this plan in order to improve utility. The challenge is to figure out the best places to insert contingency branches. This requires an estimate of how much utility could be gained by building a contingent branch at any given place in the seed plan. Computing this utility exactly is intractable, but we outline an approximation method that back propagates utility distributions through a graph structure similar to that of a plan graph.

Unit-Sphere Multiaxial Stochastic-Strength Model Applied to Anisotropic and Composite Materials

NASA Technical Reports Server (NTRS)

Nemeth, Noel, N.

2013-01-01

Models that predict the failure probability of brittle materials under multiaxial loading have been developed by authors such as Batdorf, Evans, and Matsuo. These "unit-sphere" models assume that the strength-controlling flaws are randomly oriented, noninteracting planar microcracks of specified geometry but of variable size. This methodology has been extended to predict the multiaxial strength response of transversely isotropic brittle materials, including polymer matrix composites (PMCs), by considering (1) flaw-orientation anisotropy, whereby a preexisting microcrack has a higher likelihood of being oriented in one direction over another direction, and (2) critical strength, or K (sub Ic) orientation anisotropy, whereby the level of critical strength or fracture toughness for mode I crack propagation, K (sub Ic), changes with regard to the orientation of the microstructure. In this report, results from finite element analysis of a fiber-reinforced-matrix unit cell were used with the unit-sphere model to predict the biaxial strength response of a unidirectional PMC previously reported from the World-Wide Failure Exercise. Results for nuclear-grade graphite materials under biaxial loading are also shown for comparison. This effort was successful in predicting the multiaxial strength response for the chosen problems. Findings regarding stress-state interactions and failure modes also are provided.

Orientation domains: A mobile grid clustering algorithm with spherical corrections

NASA Astrophysics Data System (ADS)

Mencos, Joana; Gratacós, Oscar; Farré, Mercè; Escalante, Joan; Arbués, Pau; Muñoz, Josep Anton

2012-12-01

An algorithm has been designed and tested which was devised as a tool assisting the analysis of geological structures solely from orientation data. More specifically, the algorithm was intended for the analysis of geological structures that can be approached as planar and piecewise features, like many folded strata. Input orientation data is expressed as pairs of angles (azimuth and dip). The algorithm starts by considering the data in Cartesian coordinates. This is followed by a search for an initial clustering solution, which is achieved by comparing the results output from the systematic shift of a regular rigid grid over the data. This initial solution is optimal (achieves minimum square error) once the grid size and the shift increment are fixed. Finally, the algorithm corrects for the variable spread that is generally expected from the data type using a reshaped non-rigid grid. The algorithm is size-oriented, which implies the application of conditions over cluster size through all the process in contrast to density-oriented algorithms, also widely used when dealing with spatial data. Results are derived in few seconds and, when tested over synthetic examples, they were found to be consistent and reliable. This makes the algorithm a valuable alternative to the time-consuming traditional approaches available to geologists.

Graph-based biomedical text summarization: An itemset mining and sentence clustering approach.

PubMed

Nasr Azadani, Mozhgan; Ghadiri, Nasser; Davoodijam, Ensieh

2018-06-12

Automatic text summarization offers an efficient solution to access the ever-growing amounts of both scientific and clinical literature in the biomedical domain by summarizing the source documents while maintaining their most informative contents. In this paper, we propose a novel graph-based summarization method that takes advantage of the domain-specific knowledge and a well-established data mining technique called frequent itemset mining. Our summarizer exploits the Unified Medical Language System (UMLS) to construct a concept-based model of the source document and mapping the document to the concepts. Then, it discovers frequent itemsets to take the correlations among multiple concepts into account. The method uses these correlations to propose a similarity function based on which a represented graph is constructed. The summarizer then employs a minimum spanning tree based clustering algorithm to discover various subthemes of the document. Eventually, it generates the final summary by selecting the most informative and relative sentences from all subthemes within the text. We perform an automatic evaluation over a large number of summaries using the Recall-Oriented Understudy for Gisting Evaluation (ROUGE) metrics. The results demonstrate that the proposed summarization system outperforms various baselines and benchmark approaches. The carried out research suggests that the incorporation of domain-specific knowledge and frequent itemset mining equips the summarization system in a better way to address the informativeness measurement of the sentences. Moreover, clustering the graph nodes (sentences) can enable the summarizer to target different main subthemes of a source document efficiently. The evaluation results show that the proposed approach can significantly improve the performance of the summarization systems in the biomedical domain. Copyright © 2018. Published by Elsevier Inc.

Some Metric Properties of Planar Gaussian Free Field

NASA Astrophysics Data System (ADS)

Goswami, Subhajit

In this thesis we study the properties of some metrics arising from two-dimensional Gaussian free field (GFF), namely the Liouville first-passage percolation (Liouville FPP), the Liouville graph distance and an effective resistance metric. In Chapter 1, we define these metrics as well as discuss the motivations for studying them. Roughly speaking, Liouville FPP is the shortest path metric in a planar domain D where the length of a path P is given by ∫Pe gammah(z)|dz| where h is the GFF on D and gamma > 0. In Chapter 2, we present an upper bound on the expected Liouville FPP distance between two typical points for small values of gamma (the near-Euclidean regime). A similar upper bound is derived in Chapter 3 for the Liouville graph distance which is, roughly, the minimal number of Euclidean balls with comparable Liouville quantum gravity (LQG) measure whose union contains a continuous path between two endpoints. Our bounds seem to be in disagreement with Watabiki's prediction (1993) on the random metric of Liouville quantum gravity in this regime. The contents of these two chapters are based on a joint work with Jian Ding. In Chapter 4, we derive some asymptotic estimates for effective resistances on a random network which is defined as follows. Given any gamma > 0 and for eta = {etav}v∈Z2 denoting a sample of the two-dimensional discrete Gaussian free field on Z2 pinned at the origin, we equip the edge ( u, v) with conductance egamma(etau + eta v). The metric structure of effective resistance plays a crucial role in our proof of the main result in Chapter 4. The primary motivation behind this metric is to understand the random walk on Z 2 where the edge (u, v) has weight egamma(etau + etav). Using the estimates from Chapter 4 we show in Chapter 5 that for almost every eta, this random walk is recurrent and that, with probability tending to 1 as T → infinity, the return probability at time 2T decays as T-1+o(1). In addition, we prove a version of subdiffusive behavior by showing that the expected exit time from a ball of radius N scales as Npsi(gamma)+o(1) with psi(gamma) > 2 for all gamma > 0. The contents of these chapters are based on a joint work with Marek Biskup and Jian Ding.

Shatter cones at the Keurusselkä impact structure and their relation to local jointing

NASA Astrophysics Data System (ADS)

Hasch, Maximilian; Reimold, Wolf Uwe; Raschke, Ulli; Zaag, Patrice Tristan

2016-08-01

Shatter cones are the only distinct meso- to macroscopic recognition criterion for impact structures, yet not all is known about their formation. The Keurusselkä impact structure, Finland, is interesting in that it presents a multitude of well-exposed shatter cones in medium- to coarse-grained granitoids. The allegedly 27 km wide Keurusselkä impact structure was formed about 1150 Ma ago in rocks of the Central Finland Granitoid Complex. Special attention was paid in this work to possible relationships between shatter cones and local, as well as regionally occurring, fracture or joint systems. A possible shatter cone find outside the previously suggested edge of the structure could mean that the Keurusselkä impact structure is larger than previously thought. The spacing between joints/fractures from regional joint systems was influenced by the impact, but impact-induced fractures strongly follow the regional joint orientation trends. There is a distinct relationship between shatter cones and joints: shatter cones occur on and against joint surfaces of varied orientations and belonging to the regional orientation trends. Planar fractures (PF) and planar deformation features (PDF) were found in three shatter cone samples from the central-most part of the impact structure, whereas other country rock samples from the same level of exposure but further from the assumed center lack shock deformation features. PDF occurrence is enhanced within 5 mm of shatter cone surfaces, which is interpreted to suggest that shock wave reverberation at preimpact joints could be responsible for this local enhancement of shock deformation. Some shatter cone surfaces are coated with a quasi-opaque material which is also found in conspicuous veinlets that branch off from shatter cone surfaces and resemble pseudotachylitic breccia veins. The vein-filling is composed of two mineral phases, one of which could be identified as a montmorillonitic phyllosilicate. The second phase could not be identified yet. The original composition of the fill could not be determined. Further work is required on this material. Observed joints and fractures were discussed against findings from Barringer impact crater. They show that impact-induced joints in the basement rock do not follow impact-specific orientations (such as radial, conical, or concentric).

Epithelial tricellular junctions act as interphase cell shape sensors to orient mitosis

PubMed Central

Bosveld, Floris; Markova, Olga; Guirao, Boris; Martin, Charlotte; Wang, Zhimin; Pierre, Anaëlle; Balakireva, Maria; Gaugue, Isabelle; Ainslie, Anna; Christophorou, Nicolas; Lubensky, David K.; Minc, Nicolas; Bellaïche, Yohanns

2017-01-01

The orientation of cell division along the interphase cell long-axis, the century old Hertwig’s rule, has profound roles in tissue proliferation, morphogenesis, architecture and mechanics1,2. In epithelial tissues, the shape of the interphase cell is influenced by cell adhesion, mechanical stress, neighbour topology, and planar polarity pathways3–12. At mitosis, epithelial cells usually round up to ensure faithful chromosome segregation and to promote morphogenesis1. The mechanisms underlying interphase cell shape sensing in tissues are therefore unknown. We found that in Drosophila epithelia, tricellular junctions (TCJ) localize microtubule force generators, orienting cell division via the Dynein associated protein Mud independently of the classical Pins/Gαi pathway. Moreover, as cells round up during mitosis, TCJs serve as spatial landmarks, encoding information about interphase cell shape anisotropy to orient division in the rounded mitotic cell. Finally, experimental and simulation data show that shape and mechanical strain sensing by the TCJ emerge from a general geometric property of TCJ distributions in epithelial tissues. Thus, in addition to their function as epithelial barrier structures, TCJs serve as polarity cues promoting geometry and mechanical sensing in epithelial tissues. PMID:26886796

Carbon-Based Nano-Electro-Mechanical-Systems

NASA Technical Reports Server (NTRS)

Kaul, A. B.; Khan, A. R.; Megerian, K. G.; Epp, L.; LeDuc, G.; Bagge, L.; Jennings, A. T.; Jang, D.; Greer, J. R.

2011-01-01

We provide an overview of our work where carbon-based nanostructures have been applied to two-dimensional (2D) planar and three-dimensional (3D) vertically-oriented nano-electro-mechanical (NEM) switches. In the first configuration, laterally oriented single-walled nanotubes (SWNTs) synthesized using thermal chemical vapor deposition (CVD) were implemented for forming bridge-type 2D NEMS switches, where switching voltages were on the order of a few volts. In the second configuration, vertically oriented carbon nanofibers (CNFs) synthesized using plasma-enhanced (PE) CVD have been explored for their potential application in 3D NEMS. We have performed nanomechanical measurements on such vertically oriented tubes using nanoindentation to determine the mechanical properties of the CNFs. Electrostatic switching was demonstrated in the CNFs synthesized on refractory metallic nitride substrates, where a nanoprobe was used as the actuating electrode inside a scanning-electron-microscope. The switching voltages were determined to be in the tens of volts range and van der Waals interactions at these length scales appeared significant, suggesting such structures are promising for nonvolatile memory applications. A finite element model was also developed to determine a theoretical pull-in voltage which was compared to experimental results.

Mode and polarization state selected guided wave spectroscopy of orientational anisotrophy in model membrane cellulosic polymer films: relevance to lab-on-a-chip

NASA Astrophysics Data System (ADS)

Andrews, Mark P.; Kanigan, Tanya

2007-06-01

Orientation anisotropies in structural properties relevant to the use of cellulosic polymers as membranes for lab-on-chips were investigated for cellulose acetate (CA) and regenerated cellulose (RC) films deposited as slab waveguides. Anisotropy was probed with mode and polarization state selected guided wave Raman spectroscopy. CA exhibits partial chain orientation in the plane of the film, and this orientation is independent of sample substrate and film preparation conditions. RC films also show in-plane anisotropy, where the hexose sugar rings lie roughly in the plane of the film. Explanations are given of the role of artifacts in interpreting waveguide Raman spectra, including anomalous contributions to Raman spectra that arise from deviations from right angle scattering geometry, mode-dependent contributions to longitudinal electric field components and TE<-->TM mode conversion. We explore diffusion profiles of small molecules in cellulosic films by adaptations of an inverse-Wentzel-Kramers-Brillouin (iWKB) recursive, noninteger virtual mode index algorithm. Perturbations in the refractive index distribution, n(z), are recovered from the measured relative propagation constants, neffective,m, of the planar waveguide. The refractive index distribution then yields the diffusion profile.

Identification of an enhancer element of class Pi glutathione S-transferase gene required for expression by a co-planar polychlorinated biphenyl.

PubMed Central

Matsumoto, M; Imagawa, M; Aoki, Y

1999-01-01

3,3',4,4',5-Pentachlorobiphenyl (PenCB), one of the most toxic co-planar polychlorinated biphenyl congeners, specifically induces class Pi glutathione S-transferase (GSTP1) as well as cytochrome P-450 1A1 in primary cultured rat liver parenchymal cells [Aoki, Matsumoto and Suzuki (1993) FEBS Lett. 333, 114-118]. However, the 5'-flanking sequence of the GSTP1 gene does not contain a xenobiotic responsive element, to which arylhydrocarbon receptor binds. Using a chloramphenicol acetyltransferase assay we demonstrate here that the enhancer termed GSTP1 enhancer I (GPEI) is necessary for the stimulation by PenCB of GSTP1 gene expression in primary cultured rat liver parenchymal cells. GPEI is already known to contain a dyad of PMA responsive element-like elements oriented palindromically. It is suggested that a novel signal transduction pathway activated by PenCB contributes to the stimulation of GSTP1 expression. PMID:10051428

Positioning of centrioles is a conserved readout of Frizzled planar cell polarity signalling

PubMed Central

Carvajal-Gonzalez, Jose Maria; Roman, Angel-Carlos; Mlodzik, Marek

2016-01-01

Planar cell polarity (PCP) signalling is a well-conserved developmental pathway regulating cellular orientation during development. An evolutionarily conserved pathway readout is not established and, moreover, it is thought that PCP mediated cellular responses are tissue-specific. A key PCP function in vertebrates is to regulate coordinated centriole/cilia positioning, a function that has not been associated with PCP in Drosophila. Here we report instructive input of Frizzled-PCP (Fz/PCP) signalling into polarized centriole positioning in Drosophila wings. We show that centrioles are polarized in pupal wing cells as a readout of PCP signalling, with both gain and loss-of-function Fz/PCP signalling affecting centriole polarization. Importantly, loss or gain of centrioles does not affect Fz/PCP establishment, implicating centriolar positioning as a conserved PCP-readout, likely downstream of PCP-regulated actin polymerization. Together with vertebrate data, these results suggest a unifying model of centriole/cilia positioning as a common downstream effect of PCP signalling from flies to mammals. PMID:27021213

Positioning of centrioles is a conserved readout of Frizzled planar cell polarity signalling.

PubMed

Carvajal-Gonzalez, Jose Maria; Roman, Angel-Carlos; Mlodzik, Marek

2016-03-29

Planar cell polarity (PCP) signalling is a well-conserved developmental pathway regulating cellular orientation during development. An evolutionarily conserved pathway readout is not established and, moreover, it is thought that PCP mediated cellular responses are tissue-specific. A key PCP function in vertebrates is to regulate coordinated centriole/cilia positioning, a function that has not been associated with PCP in Drosophila. Here we report instructive input of Frizzled-PCP (Fz/PCP) signalling into polarized centriole positioning in Drosophila wings. We show that centrioles are polarized in pupal wing cells as a readout of PCP signalling, with both gain and loss-of-function Fz/PCP signalling affecting centriole polarization. Importantly, loss or gain of centrioles does not affect Fz/PCP establishment, implicating centriolar positioning as a conserved PCP-readout, likely downstream of PCP-regulated actin polymerization. Together with vertebrate data, these results suggest a unifying model of centriole/cilia positioning as a common downstream effect of PCP signalling from flies to mammals.

Attraction between Opposing Planar Dipolar Polymer Brushes

DOE PAGES

Mahalik, J. P.; Sumpter, Bobby G.; Kumar, Rajeev

2017-08-01

In this paper, we use a field theory approach to study the effects of permanent dipoles on interpenetration and free energy changes as a function of distance between two identical planar polymer brushes. Melts (i.e., solvent-free) and solvated brushes made up of polymers grafted on nonadsorbing substrates are studied. In particular, the weak coupling limit of the dipolar interactions is considered, which leads to concentration-dependent pairwise interactions, and the effects of orientational order are neglected. It is predicted that a gradual increase in the dipole moment of the polymer segments can lead to attractive interactions between the brushes at intermediatemore » separation distances. Finally, because classical theory of polymer brushes based on the strong stretching limit (SSL) and the standard self-consistent field theory (SCFT) simulations using the Flory’s χ parameter always predicts repulsive interactions at all separations, our work highlights the importance of dipolar interactions in tailoring and accurately predicting forces between polar polymeric interfaces in contact with each other.« less

Single-frequency Nd:YAG ring lasers with corner cube prism

NASA Astrophysics Data System (ADS)

Wu, Ke Ying; Yang, Su Hui; Zhao, Chang Ming; Wei, Guang Hui

2000-04-01

Kane and Byer reported the first monolithic non-planar miniature ring lasers in 1985. An intrinsic optical diode enforces unidirectional and hence single-frequency oscillation of this device. It has the advantages of compactness, reliability and high efficiency. We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single- frequency generating. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix. The results of our initial experiment are given in the paper.

Magnetization Processes in Ribbons of Soft Magnetic Amorphous Alloys

NASA Astrophysics Data System (ADS)

Skulkina, N. A.; Ivanov, O. A.; Mazeeva, A. K.; Kuznetsov, P. A.; Stepanova, E. A.; Blinova, O. V.; Mikhalitsyna, E. A.

2018-02-01

Using iron-based (Fe-B-Si-C; Fe-Ni-Si-B) and cobalt-based (Co-Fe-Ni-Cr-Mn-Si-B) soft magnetic alloys as examples, we have studied the dependences of the remanence measured using minor hysteresis loops on the maximum induction. The different degrees of stabilization of the 180° and 90° domain walls allows these dependences to be used to analyze the magnetization processes that occur in the rapidly quenched soft magnetic alloys. It has been established from the B r( B m) dependences that, in the ribbons of soft magnetic amorphous alloys, the processes of the rotation of the magnetization oriented perpendicular to the ribbon plane start before the end of the processes of the displacement of the walls of domains with planar magnetization. After the end of the magnetization rotation processes, the magnetization processes can be interpreted as the displacement of the domain walls with a planar magnetization accompanied by a decrease in their number and a transition to a bistable state.

Discovery of microscopic evidence for shock metamorphism at the Serpent Mound structure, south-central Ohio: Confirmation of an origin by impact

USGS Publications Warehouse

Carlton, R.W.; Koeberl, C.; Baranoski, M.T.; SchuMacHer, G.A.

1998-01-01

The origin of the Serpent Mound structure in south-central Ohio has been disputed for many years. Clearly, more evidence was needed to resolve the confusion concerning the origin of the Serpent Mound feature either by endogenic processes or by hypervelocity impact. A petrographic study of 21 samples taken from a core 903 m long drilled in the central uplift of the structure provides evidence of shock metamorphism in the form of multiple sets of planar deformation features in quartz grains, as well as the presence of clasts of altered impact-melt rock. Crystallographic orientations of the planar deformation features show maxima at the shock-characteristic planes of {101??3} and {101??2} and additional maxima at {101??1}, {213??1}, and {516??1}. Geochemical analyses of impact breccias show minor enrichments in the abundances of the siderophile elements Cr, Co, Ni, and Ir, indicating the presence of a minor meteoritic component.

Extensional rheology of active suspensions

NASA Astrophysics Data System (ADS)

Saintillan, David

2010-05-01

A simple model is presented for the effective extensional rheology of a dilute suspension of active particles, such as self-propelled microswimmers, extending previous classical studies on suspensions of passive rodlike particles. Neglecting particle-particle hydrodynamic interactions, we characterize the configuration of the suspension by an orientation distribution, which satisfies a Fokker-Planck equation including the effects of an external flow field and of rotary diffusion. Knowledge of this orientation distribution then allows the determination of the particle extra stress as a configurational average of the force dipoles exerted by the particles on the fluid, which involve contributions from the imposed flow, rotary diffusion, and the permanent dipoles resulting from activity. Analytical expressions are obtained for the stress tensor in uniaxial extensional and compressional flows, as well as in planar extensional flow. In all types of flows, the effective viscosity is found to increase as a result of activity in suspensions of head-actuated swimmers (pullers) and to decrease in suspensions of tail-actuated swimmers (pushers). In the latter case, a negative particle viscosity is found to occur in weak flows. In planar extensional flow, we also characterize normal stresses, which are enhanced by activity in suspensions of pullers but reduced in suspensions of pushers. Finally, an energetic interpretation of the seemingly unphysical decrease in viscosity predicted in suspensions of pushers is proposed, where the decrease is explained as a consequence of the active power input generated by the swimming particles and is shown not to be directly related to viscous dissipative processes.

Optimizing for Large Planar Fractures in Multistage Horizontal Wells in Enhanced Geothermal Systems Using a Coupled Fluid and Geomechanics Simulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Xiexiaomen; Tutuncu, Azra; Eustes, Alfred

Enhanced Geothermal Systems (EGS) could potentially use technological advancements in coupled implementation of horizontal drilling and multistage hydraulic fracturing techniques in tight oil and shale gas reservoirs along with improvements in reservoir simulation techniques to design and create EGS reservoirs. In this study, a commercial hydraulic fracture simulation package, Mangrove by Schlumberger, was used in an EGS model with largely distributed pre-existing natural fractures to model fracture propagation during the creation of a complex fracture network. The main goal of this study is to investigate optimum treatment parameters in creating multiple large, planar fractures to hydraulically connect a horizontal injectionmore » well and a horizontal production well that are 10,000 ft. deep and spaced 500 ft. apart from each other. A matrix of simulations for this study was carried out to determine the influence of reservoir and treatment parameters on preventing (or aiding) the creation of large planar fractures. The reservoir parameters investigated during the matrix simulations include the in-situ stress state and properties of the natural fracture set such as the primary and secondary fracture orientation, average fracture length, and average fracture spacing. The treatment parameters investigated during the simulations were fluid viscosity, proppant concentration, pump rate, and pump volume. A final simulation with optimized design parameters was performed. The optimized design simulation indicated that high fluid viscosity, high proppant concentration, large pump volume and pump rate tend to minimize the complexity of the created fracture network. Additionally, a reservoir with 'friendly' formation characteristics such as large stress anisotropy, natural fractures set parallel to the maximum horizontal principal stress (SHmax), and large natural fracture spacing also promote the creation of large planar fractures while minimizing fracture complexity.« less

Mechanosensory Genes Pkd1 and Pkd2 Contribute to the Planar Polarization of Brain Ventricular Epithelium

PubMed Central

Herranz-Pérez, Vicente; Nakatani, Jin; Boletta, Alessandra; García-Verdugo, José Manuel

2015-01-01

Directional beating of ependymal (E) cells' cilia in the walls of the ventricles in the brain is essential for proper CSF flow. E cells display two forms of planar cell polarity (PCP): rotational polarity of individual cilium and translational polarity (asymmetric positioning of cilia in the apical area). The orientation of individual E cells varies according to their location in the ventricular wall (location-specific PCP). It has been hypothesized that hydrodynamic forces on the apical surface of radial glia cells (RGCs), the embryonic precursors of E cells, could guide location-specific PCP in the ventricular epithelium. However, the detection mechanisms for these hydrodynamic forces have not been identified. Here, we show that the mechanosensory proteins polycystic kidney disease 1 (Pkd1) and Pkd2 are present in primary cilia of RGCs. Ablation of Pkd1 or Pkd2 in Nestin-Cre;Pkd1flox/flox or Nestin-Cre;Pkd2flox/flox mice, affected PCP development in RGCs and E cells. Early shear forces on the ventricular epithelium may activate Pkd1 and Pkd2 in primary cilia of RGCs to properly polarize RGCs and E cells. Consistently, Pkd1, Pkd2, or primary cilia on RGCs were required for the proper asymmetric localization of the PCP protein Vangl2 in E cells' apical area. Analyses of single- and double-heterozygous mutants for Pkd1 and/or Vangl2 suggest that these genes function in the same pathway to establish E cells' PCP. We conclude that Pkd1 and Pkd2 mechanosensory proteins contribute to the development of brain PCP and prevention of hydrocephalus. SIGNIFICANCE STATEMENT This study identifies key molecules in the development of planar cell polarity (PCP) in the brain and prevention of hydrocephalus. Multiciliated ependymal (E) cells within the brain ventricular epithelium generate CSF flow through ciliary beating. E cells display location-specific PCP in the orientation and asymmetric positioning of their cilia. Defects in this PCP can result in hydrocephalus. Hydrodynamic forces on radial glial cells (RGCs), the embryonic progenitors of E cells, have been suggested to guide PCP. We show that the mechanosensory proteins Pkd1 and Pkd2 localize to primary cilia in RGCs, and their ablation disrupts the development of PCP in E cells. Early shear forces on RGCs may activate Pkd1 and Pkd2 in RGCs' primary cilia to properly orient E cells. This study identifies key molecules in the development of brain PCP and prevention of hydrocephalus. PMID:26245976

Introduction to optical methods for characterizing liquid crystals at interfaces.

PubMed

Miller, Daniel S; Carlton, Rebecca J; Mushenheim, Peter C; Abbott, Nicholas L

2013-03-12

This Instructional Review describes methods and underlying principles that can be used to characterize both the orientations assumed spontaneously by liquid crystals (LCs) at interfaces and the strength with which the LCs are held in those orientations (so-called anchoring energies). The application of these methods to several different classes of LC interfaces is described, including solid and aqueous interfaces as well as planar and nonplanar interfaces (such as those that define a LC-in-water emulsion droplet). These methods, which enable fundamental studies of the ordering of LCs at polymeric, chemically functionalized, and biomolecular interfaces, are described in this Instructional Review on a level that can be easily understood by a nonexpert reader such as an undergraduate or graduate student. We focus on optical methods because they are based on instrumentation that is found widely in research and teaching laboratories.

Surgical tool alignment guidance by drawing two cross-sectional laser-beam planes.

PubMed

Nakajima, Yoshikazu; Dohi, Takeyoshi; Sasama, Toshihiko; Momoi, Yasuyuki; Sugano, Nobuhiko; Tamura, Yuichi; Lim, Sung-hwan; Sakuma, Ichiro; Mitsuishi, Mamoru; Koyama, Tsuyoshi; Yonenobu, Kazuo; Ohashi, Satoru; Bessho, Masahiko; Ohnishi, Isao

2013-06-01

Conventional surgical navigation requires for surgeons to move their sight and conscious off the surgical field when checking surgical tool's positions shown on the display panel. Since that takes high risks of surgical exposure possibilities to the patient's body, we propose a novel method for guiding surgical tool position and orientation directly in the surgical field by a laser beam. In our navigation procedure, two cross-sectional planar laser beams are emitted from the two laser devices attached onto both sides of an optical localizer, and show surgical tool's entry position on the patient's body surface and its orientation on the side face of the surgical tool. In the experiments, our method gave the surgeons precise and accurate surgical tool adjusting and showed the feasibility to apply to both of open and percutaneous surgeries.

Intermediate regime and a phase diagram of red blood cell dynamics in a linear flow.

PubMed

Levant, Michael; Steinberg, Victor

2016-12-01

In this paper we investigate the in vitro dynamics of a single rabbit red blood cell (RBC) in a planar linear flow as a function of a shear stress σ and the dynamic viscosity of outer fluid η_{o}. A linear flow is a generalization of previous studies dynamics of soft objects including RBC in shear flow and is realized in the experiment in a microfluidic four-roll mill device. We verify that the RBC stable orientation dynamics is found in the experiment being the in-shear-plane orientation and the RBC dynamics is characterized by observed three RBC dynamical states, namely tumbling (TU), intermediate (INT), and swinging (SW) [or tank-treading (TT)] on a single RBC. The main results of these studies are the following. (i) We completely characterize the RBC dynamical states and reconstruct their phase diagram in the case of the RBC in-shear-plane orientation in a planar linear flow and find it in a good agreement with that obtained in early experiments in a shear flow for human RBCs. (ii) The value of the critical shear stress σ_{c} of the TU-TT(SW) transition surprisingly coincides with that found in early experiments in spite of a significant difference in the degree of RBC shape deformations in both the SW and INT states. (iii) We describe the INT regime, which is stationary, characterized by strong RBC shape deformations and observed in a wide range of the shear stresses. We argue that our observations cast doubts on the main claim of the recent numerical simulations that the only RBC spheroidal stress-free shape is capable to explain the early experimental data. Finally, we suggest that the amplitude dependence of both θ and the shape deformation parameter D on σ can be used as the quantitative criterion to determine the RBC stress-free shape.

Silicon Heat Pipe Array

NASA Technical Reports Server (NTRS)

Yee, Karl Y.; Ganapathi, Gani B.; Sunada, Eric T.; Bae, Youngsam; Miller, Jennifer R.; Beinsford, Daniel F.

2013-01-01

Improved methods of heat dissipation are required for modern, high-power density electronic systems. As increased functionality is progressively compacted into decreasing volumes, this need will be exacerbated. High-performance chip power is predicted to increase monotonically and rapidly with time. Systems utilizing these chips are currently reliant upon decades of old cooling technology. Heat pipes offer a solution to this problem. Heat pipes are passive, self-contained, two-phase heat dissipation devices. Heat conducted into the device through a wick structure converts the working fluid into a vapor, which then releases the heat via condensation after being transported away from the heat source. Heat pipes have high thermal conductivities, are inexpensive, and have been utilized in previous space missions. However, the cylindrical geometry of commercial heat pipes is a poor fit to the planar geometries of microelectronic assemblies, the copper that commercial heat pipes are typically constructed of is a poor CTE (coefficient of thermal expansion) match to the semiconductor die utilized in these assemblies, and the functionality and reliability of heat pipes in general is strongly dependent on the orientation of the assembly with respect to the gravity vector. What is needed is a planar, semiconductor-based heat pipe array that can be used for cooling of generic MCM (multichip module) assemblies that can also function in all orientations. Such a structure would not only have applications in the cooling of space electronics, but would have commercial applications as well (e.g. cooling of microprocessors and high-power laser diodes). This technology is an improvement over existing heat pipe designs due to the finer porosity of the wick, which enhances capillary pumping pressure, resulting in greater effective thermal conductivity and performance in any orientation with respect to the gravity vector. In addition, it is constructed of silicon, and thus is better suited for the cooling of semiconductor devices.

2-Nitro­benzyl 2-chloro­acetate

PubMed Central

Zhu, Kai; Liu, Hui; Wang, Yan-Hua; Han, Ping-Fang; Wei, Ping

2009-01-01

In the mol­ecule of the title compound, C9H8ClNO4, an intra­molecular C—H⋯O inter­action results in the formation of a near-planar (r.m.s. deviation 0.002 Å) five-membered ring, which is oriented at a dihedral angle of 4.07 (4)° with respect to the adjacent aromatic ring. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules into a two-dimensional network. PMID:21577790

Channeling and radiation of 855 MeV electrons and positrons in straight and bent tungsten (1 1 0) crystals

NASA Astrophysics Data System (ADS)

Shen, H.; Zhao, Q.; Zhang, F. S.; Sushko, Gennady B.; Korol, Andrei V.; Solov'yov, Andrey V.

2018-06-01

Planar channeling of 855 MeV electrons and positrons in straight and bent tungsten (1 1 0) crystal is simulated by means of the MBN EXPLORER software package. The results of simulations for a broad range of bending radii are analyzed in terms of the channel acceptance, dechanneling length, and spectral distribution of the emitted radiation. Comparison of the results with predictions of other theories as well as with the data for (1 1 0) oriented diamond, silicon and germanium crystals is carried out.

Apparatus and method for electroforming high aspect ratio micro-parts

DOEpatents

Hachman, John T [Stockton, CA; Losey, Matthew W [Rancho Cucamonga, CA; McLean, Dorrance E [Manteca, CA

2009-11-27

A fixture is disclosed to more easily affix a workpiece in the proper orientation and spacing with sealed electrical interconnection within an electrochemical plating bath. The workpiece can be any planar metallic or non-metallic substrate such as a silicon wafer commonly used in LIGA or microsystem fabrication. The fixture described allows the workpiece to be submerged deep within an electrolytic cell, facing upwards, and allows easy transfer from one cell to another. The edges, backside, and electrical connections are sealed and protected from the electrolyte.

Geologic map of the Julian 7.5' quadrangle, San Diego County, California

USGS Publications Warehouse

Todd, Victoria R.

2015-01-01

Jurassic plutons in the Julian quadrangle underwent synkinematic metamorphism with the result that plutonic contacts and foliation are concordant with those in the surrounding metamorphosed country rocks. Foliation in Jurassic plutons consists of the planar orientation of recrystallized mineral grains and aggregates; deformation textures include augen gneiss, mylonitic gneiss, and mylonite. Structural studies indicate that a significant part of this deformation took place in the Cretaceous and, therefore, the regional foliation in this part of the batholith clearly postdates intrusion of many Cretaceous plutons.

Addressing the Limit of Detectability of Residual Oxide Discontinuities in Friction Stir Butt Welds of Aluminum using Phased Array Ultrasound

NASA Technical Reports Server (NTRS)

Johnston, P. H.

2008-01-01

This activity seeks to estimate a theoretical upper bound of detectability for a layer of oxide embedded in a friction stir weld in aluminum. The oxide is theoretically modeled as an ideal planar layer of aluminum oxide, oriented normal to an interrogating ultrasound beam. Experimentally-measured grain scattering level is used to represent the practical noise floor. Echoes from naturally-occurring oxides will necessarily fall below this theoretical limit, and must be above the measurement noise to be potentially detectable.

Theory of electrical conductivity and dielectric permittivity of highly aligned graphene-based nanocomposites.

PubMed

Xia, Xiaodong; Hao, Jia; Wang, Yang; Zhong, Zheng; Weng, George J

2017-05-24

Highly aligned graphene-based nanocomposites are of great interest due to their excellent electrical properties along the aligned direction. Graphene fillers in these composites are not necessarily perfectly aligned, but their orientations are highly confined to a certain angle, [Formula: see text] with 90° giving rise to the randomly oriented state and 0° to the perfectly aligned one. Recent experiments have shown that electrical conductivity and dielectric permittivity of highly aligned graphene-polymer nanocomposites are strongly dependent on this distribution angle, but at present no theory seems to exist to address this issue. In this work we present a new effective-medium theory that is derived from the underlying physical process including the effects of graphene orientation, filler loading, aspect ratio, percolation threshold, interfacial tunneling, and Maxwell-Wagner-Sillars polarization, to determine these two properties. The theory is formulated in the context of preferred orientational average. We highlight this new theory with an application to rGO/epoxy nanocomposites, and demonstrate that the calculated in-plane and out-of-plane conductivity and permittivity are in agreement with the experimental data as the range of graphene orientations changes from the randomly oriented to the highly aligned state. We also show that the percolation thresholds of highly aligned graphene nanocomposites are in general different along the planar and the normal directions, but they converge into a single one when the statistical distribution of graphene fillers is spherically symmetric.

An alternative database approach for management of SNOMED CT and improved patient data queries.

PubMed

Campbell, W Scott; Pedersen, Jay; McClay, James C; Rao, Praveen; Bastola, Dhundy; Campbell, James R

2015-10-01

SNOMED CT is the international lingua franca of terminologies for human health. Based in Description Logics (DL), the terminology enables data queries that incorporate inferences between data elements, as well as, those relationships that are explicitly stated. However, the ontologic and polyhierarchical nature of the SNOMED CT concept model make it difficult to implement in its entirety within electronic health record systems that largely employ object oriented or relational database architectures. The result is a reduction of data richness, limitations of query capability and increased systems overhead. The hypothesis of this research was that a graph database (graph DB) architecture using SNOMED CT as the basis for the data model and subsequently modeling patient data upon the semantic core of SNOMED CT could exploit the full value of the terminology to enrich and support advanced data querying capability of patient data sets. The hypothesis was tested by instantiating a graph DB with the fully classified SNOMED CT concept model. The graph DB instance was tested for integrity by calculating the transitive closure table for the SNOMED CT hierarchy and comparing the results with transitive closure tables created using current, validated methods. The graph DB was then populated with 461,171 anonymized patient record fragments and over 2.1 million associated SNOMED CT clinical findings. Queries, including concept negation and disjunction, were then run against the graph database and an enterprise Oracle relational database (RDBMS) of the same patient data sets. The graph DB was then populated with laboratory data encoded using LOINC, as well as, medication data encoded with RxNorm and complex queries performed using LOINC, RxNorm and SNOMED CT to identify uniquely described patient populations. A graph database instance was successfully created for two international releases of SNOMED CT and two US SNOMED CT editions. Transitive closure tables and descriptive statistics generated using the graph database were identical to those using validated methods. Patient queries produced identical patient count results to the Oracle RDBMS with comparable times. Database queries involving defining attributes of SNOMED CT concepts were possible with the graph DB. The same queries could not be directly performed with the Oracle RDBMS representation of the patient data and required the creation and use of external terminology services. Further, queries of undefined depth were successful in identifying unknown relationships between patient cohorts. The results of this study supported the hypothesis that a patient database built upon and around the semantic model of SNOMED CT was possible. The model supported queries that leveraged all aspects of the SNOMED CT logical model to produce clinically relevant query results. Logical disjunction and negation queries were possible using the data model, as well as, queries that extended beyond the structural IS_A hierarchy of SNOMED CT to include queries that employed defining attribute-values of SNOMED CT concepts as search parameters. As medical terminologies, such as SNOMED CT, continue to expand, they will become more complex and model consistency will be more difficult to assure. Simultaneously, consumers of data will increasingly demand improvements to query functionality to accommodate additional granularity of clinical concepts without sacrificing speed. This new line of research provides an alternative approach to instantiating and querying patient data represented using advanced computable clinical terminologies. Copyright © 2015 Elsevier Inc. All rights reserved.

Warts phosphorylates Mud to promote Pins-mediated mitotic spindle orientation in Drosophila independent of Yorkie

PubMed Central

Dewey, Evan B.; Sanchez, Desiree; Johnston, Christopher A.

2015-01-01

SUMMARY Multicellular animals have evolved conserved signaling pathways that translate cell polarity cues into mitotic spindle positioning to control the orientation of cell division within complex tissue structures. These oriented cell divisions are essential for the development of cell diversity and the maintenance of tissue homeostasis. Despite intense efforts, the molecular mechanisms that control spindle orientation remain incompletely defined. Here we describe a role for the Hippo (Hpo) kinase complex in promoting Partner of Inscuteable (Pins)-mediated spindle orientation. Knockdown of Hpo, Salvador (Sav), or Warts (Wts) each result in a partial loss of spindle orientation, a phenotype previously described following loss of the Pins-binding protein Mushroom body defect (Mud). Similar to orthologs spanning yeast to mammals, Wts kinase localizes to mitotic spindle poles, a prominent site of Mud localization. Wts directly phosphorylates Mud in vitro within its C-terminal coiled-coil domain. This Mud coiled-coil domain directly binds the adjacent Pins-binding domain to dampen the Pins/Mud interaction, and Wts-mediated phosphorylation uncouples this intramolecular Mud interaction. Loss of Wts prevents cortical Pins/Mud association without affecting Mud accumulation at spindle poles, suggesting phosphorylation acts as a molecular switch to specifically activate cortical Mud function. Finally, loss of Wts in Drosophila imaginal disc epithelial cells results in diminished cortical Mud and defective planar spindle orientation. Our results provide new insights into the molecular basis for dynamic regulation of the cortical Pins/Mud spindle positioning complex and highlight a novel link with an essential, evolutionarily-conserved cell proliferation pathway. PMID:26592339

A Micromagnetic Study of Medium Orientation Ratio Effects in High Areal Density Recording

NASA Astrophysics Data System (ADS)

Plumer, Martin; van Ek, Johannes

2000-03-01

An extensive analysis of written tracks on granular media with anisotropy axes preferentially oriented either in the down-track or cross-track direction was performed with a newly developed micromagnetic model of magnetic recording [1]. The response of planar media to writer head fields, derived from the Finite-Element-Method, is calculated by solving the LLG equations. Signal from the written transitions is determined through a micromagnetic model of a GMR spin-valve device. Using fields from a generic 10Gb/in2 head (TPWG=0.6um, gap=0.2um, 1.8T materials around the gap), dibits were written at high linear density. Relative to the isotropic case, both erase bands and read-back voltage deteriorate for cross-track oriented media and improve in the down-track orientation case. For an orientation ratio of 1.23, the read-back signal at 200 kbpi drops by 15% in the radial case and increases by 15% in the circumferential case. Although the cross-track coercivity is smaller for down-track oriented media, and thus easier to write with the corners of the head, the remnant cross-track magnetization is correspondingly smaller. Track edge distortion is thus less severe than for isotropic media. Oriented media is of interest due to enhanced thermal stability and faster switching times [2]. [1] J. van Ek, M.L. Plumer, H. Zhou and H.N. Bertram, ``A Micromagnetic Recording Model for Write and Read-back," in preparation. Also see the GMAG symposium, this conference. [2] E.N. Abarra, I. Okamoto and M. Shinohara, IEEE Trans. Mag. 35, 2709 (1999).

Warts phosphorylates mud to promote pins-mediated mitotic spindle orientation in Drosophila, independent of Yorkie.

PubMed

Dewey, Evan B; Sanchez, Desiree; Johnston, Christopher A

2015-11-02

Multicellular animals have evolved conserved signaling pathways that translate cell polarity cues into mitotic spindle positioning to control the orientation of cell division within complex tissue structures. These oriented cell divisions are essential for the development of cell diversity and the maintenance of tissue homeostasis. Despite intense efforts, the molecular mechanisms that control spindle orientation remain incompletely defined. Here, we describe a role for the Hippo (Hpo) kinase complex in promoting Partner of Inscuteable (Pins)-mediated spindle orientation. Knockdown of Hpo, Salvador (Sav), or Warts (Wts) each result in a partial loss of spindle orientation, a phenotype previously described following loss of the Pins-binding protein Mushroom body defect (Mud). Similar to orthologs spanning yeast to mammals, Wts kinase localizes to mitotic spindle poles, a prominent site of Mud localization. Wts directly phosphorylates Mud in vitro within its C-terminal coiled-coil domain. This Mud coiled-coil domain directly binds the adjacent Pins-binding domain to dampen the Pins/Mud interaction, and Wts-mediated phosphorylation uncouples this intramolecular Mud interaction. Loss of Wts prevents cortical Pins/Mud association without affecting Mud accumulation at spindle poles, suggesting phosphorylation acts as a molecular switch to specifically activate cortical Mud function. Finally, loss of Wts in Drosophila imaginal disc epithelial cells results in diminished cortical Mud and defective planar spindle orientation. Our results provide new insights into the molecular basis for dynamic regulation of the cortical Pins/Mud spindle positioning complex and highlight a novel link with an essential, evolutionarily conserved cell proliferation pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

Curvature-driven capillary migration and assembly of rod-like particles

PubMed Central

Cavallaro, Marcello; Botto, Lorenzo; Lewandowski, Eric P.; Wang, Marisa; Stebe, Kathleen J.

2011-01-01

Capillarity can be used to direct anisotropic colloidal particles to precise locations and to orient them by using interface curvature as an applied field. We show this in experiments in which the shape of the interface is molded by pinning to vertical pillars of different cross-sections. These interfaces present well-defined curvature fields that orient and steer particles along complex trajectories. Trajectories and orientations are predicted by a theoretical model in which capillary forces and torques are related to Gaussian curvature gradients and angular deviations from principal directions of curvature. Interface curvature diverges near sharp boundaries, similar to an electric field near a pointed conductor. We exploit this feature to induce migration and assembly at preferred locations, and to create complex structures. We also report a repulsive interaction, in which microparticles move away from planar bounding walls along curvature gradient contours. These phenomena should be widely useful in the directed assembly of micro- and nanoparticles with potential application in the fabrication of materials with tunable mechanical or electronic properties, in emulsion production, and in encapsulation. PMID:22184218

Vibrational sum-frequency generation spectroscopy of ionic liquid 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate at the air-water interface

NASA Astrophysics Data System (ADS)

Saha, Ankur; SenGupta, Sumana; Kumar, Awadhesh; Choudhury, Sipra; Naik, Prakash D.

2016-08-01

The structure and orientation of room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate [PF3(C2F5)3], commonly known as [bmim][fap], have been investigated at the air-[bmim][fap] and air-water interfaces, employing vibrational sum-frequency generation (VSFG) spectroscopy. The VSFG spectra in the CH stretch region suggest presence of the [bmim] cation at the interfaces. Studies reveal that the butyl chain protrudes out into air, and the imidazolium ring lies almost planar to the interface. The CH stretch intensities get enhanced at the air-water interface, mainly because of polar orientation of imidazolium cation induced by interfacial water molecules. The OH stretch intensities are also enhanced at the air-water interface due to polar orientation of interfacial water molecules induced by [bmim][fap]. The Brewster angle microscopy suggests self aggregation of [bmim][fap] in the presence of water, and the aggregation becomes extensive showing dense surface domains with time. However, the surface pressure is almost unaffected due to aggregation.

Topologically and geometrically flexible structural units in seven new organically templated uranyl selenates and selenite–selenates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru; Kovrugin, Vadim M.; Tyumentseva, Olga S.

2015-09-15

Single crystals of seven novel uranyl oxysalts of selenium with protonated methylamine molecules, [C{sub 2}H{sub 8}N]{sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)] (I), [C{sub 2}H{sub 8}N]{sub 2}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3}(H{sub 2}O)] (II), [C{sub 4}H{sub 15}N{sub 3}][H{sub 3}O]{sub 0.5}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 2.93}(SeO{sub 3}){sub 0.07}(H{sub 2}O)](NO{sub 3}){sub 0.5} (III), [C{sub 2}H{sub 8}N]{sub 3}[H{sub 5}O{sub 2}][(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sub 2}(H{sub 2}O){sub 5} (IV), [C{sub 2}H{sub 8}N]{sub 2}[H{sub 3}O][(UO{sub 2}){sub 3}(SeO{sub 4}){sub 4}(HSeO{sub 3})(H{sub 2}O)](H{sub 2}SeO{sub 3}){sub 0.2} (V), [C{sub 4}H{sub 12}N]{sub 3}[H{sub 3}O][(UO{sub 2}){sub 3}(SeO{sub 4}){sub 5}(H{sub 2}O)] (VI), and [C{sub 2}H{sub 8}N]{sub 3}(C{sub 2}H{sub 7}N)[(UO{sub 2}){sub 3}(SeO{sub 4}){submore » 4}(HSeO{sub 3})(H{sub 2}O)] (VII) have been prepared by isothermal evaporation from aqueous solutions. Their crystal structures have been solved by direct methods and their uranyl selenate and selenite–selenate units investigated using black-and-white graphs from the viewpoints of topology of interpolyhedral linkages and isomeric variations. The crystal structure of IV is based upon complex layers with unique topology, which has not been observed previously in uranyl selenates. Investigations of the statistics and local distribution of the U–O{sub br}–Se bond angles demonstrates that shorter angles associate with undulations, whereas larger angles correspond to planar areas of the uranyl selenite layers. - Graphical abstract: Crystal structures of the seven novel Se-contaning uranyl oxysalts that contain protonated organic molecules as interlayer species have been investigated from the viewpoints of topology of interpolyhedral linkages, isomeric variations and flexibility of structural units. - Highlights: • Single crystals of seven novel uranyl oxysalts were prepared by evaporation method. • The graph theory was used for investigation of topologies of structural units. • The method of orientation matrices was applied to distinguish geometrical isomers. • The flexibility of structural complexes specifies the undulation of layered structural units.« less

Material orientation design of planar structures with prescribed anisotropy classes. Study of rhombic systems

NASA Astrophysics Data System (ADS)

Czubacki, Radosław

2018-01-01

The paper deals with the minimum compliance problem of 2D structures made of a non-homogeneous elastic material. In the first part of the paper a comparison between solutions of Free Material Design (FMD), Cubic Material Design (CMD) and Isotropic Material Design (IMD) is shown for a simply supported plate in a shape of a deep beam, subjected to a concentrated in-plane force at its upper face. The isoperimetric condition fixes the value of the cost of the design expressed as the integral of the trace of the Hooke tensor. In the second part of the paper the material design approaches are extended to rhombic system in 2D. For the rhombic system the material properties of the structures are set, the design variables being the trajectories of anisotropy directions which in 2D are described by one parameter. In the Orthotropic Orientation Design (OOD) no isoperimetric condition is used.

Polymer-dispersed liquid crystal elastomers

NASA Astrophysics Data System (ADS)

Rešetič, Andraž; Milavec, Jerneja; Zupančič, Blaž; Domenici, Valentina; Zalar, Boštjan

2016-10-01

The need for mechanical manipulation during the curing of conventional liquid crystal elastomers diminishes their applicability in the field of shape-programmable soft materials and future applications in additive manufacturing. Here we report on polymer-dispersed liquid crystal elastomers, novel composite materials that eliminate this difficulty. Their thermal shape memory anisotropy is imprinted by curing in external magnetic field, providing for conventional moulding of macroscopically sized soft, thermomechanically active elastic objects of general shapes. The binary soft-soft composition of isotropic elastomer matrix, filled with freeze-fracture-fabricated, oriented liquid crystal elastomer microparticles as colloidal inclusions, allows for fine-tuning of thermal morphing behaviour. This is accomplished by adjusting the concentration, spatial distribution and orientation of microparticles or using blends of microparticles with different thermomechanical characteristics. We demonstrate that any Gaussian thermomechanical deformation mode (bend, cup, saddle, left and right twist) of a planar sample, as well as beat-like actuation, is attainable with bilayer microparticle configurations.

Instabilities, rheology and spontaneous flows in magnetotactic bacterial suspensions

NASA Astrophysics Data System (ADS)

Alonso-Matilla, Roberto; Saintillan, David

2017-11-01

Magnetotactic bacteria are motile prokaryotes, mostly present in marine habitats, that synthesize intracellular magnetic membrane-bounded crystals known as magnetosomes. They behave as self-propelled permanent magnetic dipoles that orient and migrate along the geomagnetic field lines of the Earth. In this work, we analyze the macroscopic transport properties of suspensions of such bacteria in microfluidic devices. When placed in an external magnetic field, these microorganisms feel a net magnetic torque which is transmitted to the surrounding fluid, and can give rise to a net unidirectional fluid flow in a planar channel, with a flow rate and direction that can be controlled by adjusting both the magnitude and orientation of the external field. Using a continuum kinetic model, we provide a physical explanation for the onset of these spontaneous flows. We also study the rheological properties and stability of these suspensions in both an applied shear flow and a pressure-driven flow.

Large-Area Direct Hetero-Epitaxial Growth of 1550-nm InGaAsP Multi-Quantum-Well Structures on Patterned Exact-Oriented (001) Silicon Substrates by Metal Organic Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Megalini, Ludovico; Cabinian, Brian C.; Zhao, Hongwei; Oakley, Douglas C.; Bowers, John E.; Klamkin, Jonathan

2018-02-01

We employ a simple two-step growth technique to grow large-area 1550-nm laser structures by direct hetero-epitaxy of III-V compounds on patterned exact-oriented (001) silicon (Si) substrates by metal organic chemical vapor deposition. Densely-packed, highly uniform, flat and millimeter-long indium phosphide (InP) nanowires were grown from Si v-grooves separated by silicon dioxide (SiO2) stripes with various widths and pitches. Following removal of the SiO2 patterns, the InP nanowires were coalesced and, subsequently, 1550-nm laser structures were grown in a single overgrowth without performing any polishing for planarization. X-ray diffraction, photoluminescence, atomic force microscopy and transmission electron microscopy analyses were used to characterize the epitaxial material. PIN diodes were fabricated and diode-rectifying behavior was observed.

Acoustic and optical borehole-wall imaging for fractured-rock aquifer studies

USGS Publications Warehouse

Williams, J.H.; Johnson, C.D.

2004-01-01

Imaging with acoustic and optical televiewers results in continuous and oriented 360?? views of the borehole wall from which the character, relation, and orientation of lithologic and structural planar features can be defined for studies of fractured-rock aquifers. Fractures are more clearly defined under a wider range of conditions on acoustic images than on optical images including dark-colored rocks, cloudy borehole water, and coated borehole walls. However, optical images allow for the direct viewing of the character of and relation between lithology, fractures, foliation, and bedding. The most powerful approach is the combined application of acoustic and optical imaging with integrated interpretation. Imaging of the borehole wall provides information useful for the collection and interpretation of flowmeter and other geophysical logs, core samples, and hydraulic and water-quality data from packer testing and monitoring. ?? 2003 Elsevier B.V. All rights reserved.

Influence of surface oxidation on ion dynamics and capacitance in porous and nonporous carbon electrodes

DOE PAGES

Dyatkin, Boris; Zhang, Yu; Mamontov, Eugene; ...

2016-04-07

Here, we investigate the influence of surface chemistry and ion confinement on capacitance and electrosorption dynamics of room-temperature ionic liquids (RTILs) in supercapacitors. Using air oxidation and vacuum annealing, we produced defunctionalized and oxygen-rich surfaces of carbide-derived carbons (CDCs) and graphene nanoplatelets (GNPs). While oxidized surfaces of porous CDCs improve capacitance and rate handling abilities of ions, defunctionalized nonporous GNPs improve charge storage densities on planar electrodes. Quasi-elastic neutron scattering (QENS) and inelastic neutron scattering (INS) probed the structure, dynamics, and orientation of RTIL ions confined in divergently functionalized pores. Oxidized, ionophilic surfaces draw ions closer to pore surfaces andmore » enhance potential-driven ion transport during electrosorption. Molecular dynamics (MD) simulations corroborated experimental data and demonstrated the significance of surface functional groups on ion orientations, accumulation densities, and capacitance.« less

Arc_Mat: a Matlab-based spatial data analysis toolbox

NASA Astrophysics Data System (ADS)

Liu, Xingjian; Lesage, James

2010-03-01

This article presents an overview of Arc_Mat, a Matlab-based spatial data analysis software package whose source code has been placed in the public domain. An earlier version of the Arc_Mat toolbox was developed to extract map polygon and database information from ESRI shapefiles and provide high quality mapping in the Matlab software environment. We discuss revisions to the toolbox that: utilize enhanced computing and graphing capabilities of more recent versions of Matlab, restructure the toolbox with object-oriented programming features, and provide more comprehensive functions for spatial data analysis. The Arc_Mat toolbox functionality includes basic choropleth mapping; exploratory spatial data analysis that provides exploratory views of spatial data through various graphs, for example, histogram, Moran scatterplot, three-dimensional scatterplot, density distribution plot, and parallel coordinate plots; and more formal spatial data modeling that draws on the extensive Spatial Econometrics Toolbox functions. A brief review of the design aspects of the revised Arc_Mat is described, and we provide some illustrative examples that highlight representative uses of the toolbox. Finally, we discuss programming with and customizing the Arc_Mat toolbox functionalities.

A large-grain mapping approach for multiprocessor systems through data flow model. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Kim, Hwa-Soo

1991-01-01

A large-grain level mapping method is presented of numerical oriented applications onto multiprocessor systems. The method is based on the large-grain data flow representation of the input application and it assumes a general interconnection topology of the multiprocessor system. The large-grain data flow model was used because such representation best exhibits inherited parallelism in many important applications, e.g., CFD models based on partial differential equations can be presented in large-grain data flow format, very effectively. A generalized interconnection topology of the multiprocessor architecture is considered, including such architectural issues as interprocessor communication cost, with the aim to identify the 'best matching' between the application and the multiprocessor structure. The objective is to minimize the total execution time of the input algorithm running on the target system. The mapping strategy consists of the following: (1) large-grain data flow graph generation from the input application using compilation techniques; (2) data flow graph partitioning into basic computation blocks; and (3) physical mapping onto the target multiprocessor using a priority allocation scheme for the computation blocks.

Reaction Mechanism Generator: Automatic construction of chemical kinetic mechanisms

DOE PAGES

Gao, Connie W.; Allen, Joshua W.; Green, William H.; ...

2016-02-24

Reaction Mechanism Generator (RMG) constructs kinetic models composed of elementary chemical reaction steps using a general understanding of how molecules react. Species thermochemistry is estimated through Benson group additivity and reaction rate coefficients are estimated using a database of known rate rules and reaction templates. At its core, RMG relies on two fundamental data structures: graphs and trees. Graphs are used to represent chemical structures, and trees are used to represent thermodynamic and kinetic data. Models are generated using a rate-based algorithm which excludes species from the model based on reaction fluxes. RMG can generate reaction mechanisms for species involvingmore » carbon, hydrogen, oxygen, sulfur, and nitrogen. It also has capabilities for estimating transport and solvation properties, and it automatically computes pressure-dependent rate coefficients and identifies chemically-activated reaction paths. RMG is an object-oriented program written in Python, which provides a stable, robust programming architecture for developing an extensible and modular code base with a large suite of unit tests. Computationally intensive functions are cythonized for speed improvements.« less

Estimating average shock pressures recorded by impactite samples based on universal stage investigations of planar deformation features in quartz - Sources of error and recommendations

NASA Astrophysics Data System (ADS)

Holm-Alwmark, S.; Ferrière, L.; Alwmark, C.; Poelchau, M. H.

2018-01-01

Planar deformation features (PDFs) in quartz are the most widely used indicator of shock metamorphism in terrestrial rocks. They can also be used for estimating average shock pressures that quartz-bearing rocks have been subjected to. Here we report on a number of observations and problems that we have encountered when performing universal stage measurements and crystallographically indexing of PDF orientations in quartz. These include a comparison between manual and automated methods of indexing PDFs, an evaluation of the new stereographic projection template, and observations regarding the PDF statistics related to the c-axis position and rhombohedral plane symmetry. We further discuss the implications that our findings have for shock barometry studies. Our study shows that the currently used stereographic projection template for indexing PDFs in quartz might induce an overestimation of rhombohedral planes with low Miller-Bravais indices. We suggest, based on a comparison of different shock barometry methods, that a unified method of assigning shock pressures to samples based on PDFs in quartz is necessary to allow comparison of data sets. This method needs to take into account not only the average number of PDF sets/grain but also the number of high Miller-Bravais index planes, both of which are important factors according to our study. Finally, we present a suggestion for such a method (which is valid for nonporous quartz-bearing rock types), which consists of assigning quartz grains into types (A-E) based on the PDF orientation pattern, and then calculation of a mean shock pressure for each sample.

Gravity Influences the Visual Representation of Object Tilt in Parietal Cortex

PubMed Central

Angelaki, Dora E.

2014-01-01

Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an “earth-vertical” direction. PMID:25339732

Fabrication of Ti substrate grain dependent C/TiO2 composites through carbothermal treatment of anodic TiO2.

PubMed

Rüdiger, Celine; Favaro, Marco; Valero-Vidal, Carlos; Calvillo, Laura; Bozzolo, Nathalie; Jacomet, Suzanne; Hejny, Clivia; Gregoratti, Luca; Amati, Matteo; Agnoli, Stefano; Granozzi, Gaetano; Kunze-Liebhäuser, Julia

2016-04-07

Composite materials of titania and graphitic carbon, and their optimized synthesis are highly interesting for application in sustainable energy conversion and storage. We report on planar C/TiO2 composite films that are prepared on a polycrystalline titanium substrate by carbothermal treatment of compact anodic TiO2 with acetylene. This thin film material allows for the study of functional properties of C/TiO2 as a function of chemical composition and structure. The chemical and structural properties of the composite on top of individual Ti substrate grains are examined by scanning photoelectron microscopy and micro-Raman spectroscopy. Through comparison of these data with electron backscatter diffraction, it is found that the amount of generated carbon and the grade of anodic film crystallinity correlate with the crystallographic orientation of the Ti substrate grains. On top of Ti grains with ∼(0001) orientations the anodic TiO2 exhibits the highest grade of crystallinity, and the composite contains the highest fraction of graphitic carbon compared to Ti grains with other orientations. This indirect effect of the Ti substrate grain orientation yields new insights into the activity of TiO2 towards the decomposition of carbon precursors.

Insights into the effects of solvent properties in graphene based electric double-layer capacitors with organic electrolytes

NASA Astrophysics Data System (ADS)

Zhang, Shuo; Bo, Zheng; Yang, Huachao; Yang, Jinyuan; Duan, Liangping; Yan, Jianhua; Cen, Kefa

2016-12-01

Organic electrolytes are widely used in electric double-layer capacitors (EDLCs). In this work, the microstructure of planar graphene-based EDLCs with different organic solvents are investigated with molecular dynamics simulations. Results show that an increase of solvent polarity could weaken the accumulation of counter-ions nearby the electrode surface, due to the screen of electrode charges and relatively lower ionic desolvation. It thus suggests that solvents with low polarity could be preferable to yield high EDL capacitance. Meanwhile, the significant effects of the size and structure of solvent molecules are reflected by non-electrostatic molecule-electrode interactions, further influencing the adsorption of solvent molecules on electrode surface. Compared with dimethyl carbonate, γ-butyrolactone, and propylene carbonate, acetonitrile with relatively small-size and linear structure owns weak non-electrostatic interactions, which favors the easy re-orientation of solvent molecules. Moreover, the shift of solvent orientation in surface layer, from parallel orientation to perpendicular orientation relative to the electrode surface, deciphers the solvent twin-peak behavior near negative electrode. The as-obtained insights into the roles of solvent properties on the interplays among particles and electrodes elucidate the solvent influences on the microstructure and capacitive behavior of EDLCs using organic electrolytes.

27 T ultra-high static magnetic field changes orientation and morphology of mitotic spindles in human cells

PubMed Central

Zhang, Lei; Hou, Yubin; Li, Zhiyuan; Ji, Xinmiao; Wang, Ze; Wang, Huizhen; Tian, Xiaofei; Yu, Fazhi; Yang, Zhenye; Pi, Li; Mitchison, Timothy J; Lu, Qingyou; Zhang, Xin

2017-01-01

Purified microtubules have been shown to align along the static magnetic field (SMF) in vitro because of their diamagnetic anisotropy. However, whether mitotic spindle in mammalian cells can be aligned by magnetic field has not been experimentally proved. In particular, the biological effects of SMF of above 20 T (Tesla) on mammalian cells have never been reported. Here we found that in both CNE-2Z and RPE1 human cells spindle orients in 27 T SMF. The direction of spindle alignment depended on the extent to which chromosomes were aligned to form a planar metaphase plate. Our results show that the magnetic torque acts on both microtubules and chromosomes, and the preferred direction of spindle alignment relative to the field depends more on chromosome alignment than microtubules. In addition, spindle morphology was also perturbed by 27 T SMF. This is the first reported study that investigated the mammalian cellular responses to ultra-high magnetic field of above 20 T. Our study not only found that ultra-high magnetic field can change the orientation and morphology of mitotic spindles, but also provided a tool to probe the role of spindle orientation and perturbation in developmental and cancer biology. DOI: http://dx.doi.org/10.7554/eLife.22911.001 PMID:28244368

Character expansion methods for matrix models of dually weighted graphs

NASA Astrophysics Data System (ADS)

Kazakov, Vladimir A.; Staudacher, Matthias; Wynter, Thomas

1996-04-01

We consider generalized one-matrix models in which external fields allow control over the coordination numbers on both the original and dual lattices. We rederive in a simple fashion a character expansion formula for these models originally due to Itzykson and Di Francesco, and then demonstrate how to take the large N limit of this expansion. The relationship to the usual matrix model resolvent is elucidated. Our methods give as a by-product an extremely simple derivation of the Migdal integral equation describing the large N limit of the Itzykson-Zuber formula. We illustrate and check our methods by analysing a number of models solvable by traditional means. We then proceed to solve a new model: a sum over planar graphys possessing even coordination numbers on both the original and the dual lattice. We conclude by formulating the equations for the case of arbitrary sets of even, self-dual coupling constants. This opens the way for studying the deep problems of phase transitions from random to flat lattices. January 1995

Two Seating Systems' Effects on an Adolescent With Cerebral Palsy and Severe Scoliosis.

PubMed

Lephart, Kim; Kaplan, Sandra L

2015-01-01

To compare physiological functioning, communication switch activation, and response accuracy in a 19-year-old young man with quadriplegic cerebral palsy and neurological scoliosis using 2 seating systems within the school setting. Prospective single-subject alternating treatment design with 2 conditions: baseline phase with standard planar inserts (A1), custom-molded back with original seat (B), and return to baseline (A2). Measures included oxygen saturation (SaO2), heart rate (HR), respiration rate (RR), body temperature (BT), processing time to activate switches, and response accuracy. SaO2 levels increased from "distressed" to "normal"; variability decreased. HR, RR, and BT fluctuations decreased with the custom-molded back. Processing time decreased with increased variability, affected by subject's motivation; accuracy improved slightly. Reported social approachability and student-initiated communication increased. SaO2 increased and HR, RR, and BT fluctuations decreased with a custom-molded back. Graphing data may help determine seating effect with complex clients.

What graph theory actually tells us about resting state interictal MEG epileptic activity.

PubMed

Niso, Guiomar; Carrasco, Sira; Gudín, María; Maestú, Fernando; Del-Pozo, Francisco; Pereda, Ernesto

2015-01-01

Graph theory provides a useful framework to study functional brain networks from neuroimaging data. In epilepsy research, recent findings suggest that it offers unique insight into the fingerprints of this pathology on brain dynamics. Most studies hitherto have focused on seizure activity during focal epilepsy, but less is known about functional epileptic brain networks during interictal activity in frontal focal and generalized epilepsy. Besides, it is not clear yet which measures are most suitable to characterize these networks. To address these issues, we recorded magnetoencephalographic (MEG) data using two orthogonal planar gradiometers from 45 subjects from three groups (15 healthy controls (7 males, 24 ± 6 years), 15 frontal focal (8 male, 32 ± 16 years) and 15 generalized epileptic (6 male, 27 ± 7 years) patients) during interictal resting state with closed eyes. Then, we estimated the total and relative spectral power of the largest principal component of the gradiometers, and the degree of phase synchronization between each sensor site in the frequency range [0.5-40 Hz]. We further calculated a comprehensive battery of 15 graph-theoretic measures and used the affinity propagation clustering algorithm to elucidate the minimum set of them that fully describe these functional brain networks. The results show that differences in spectral power between the control and the other two groups have a distinctive pattern: generalized epilepsy presents higher total power for all frequencies except the alpha band over a widespread set of sensors; frontal focal epilepsy shows higher relative power in the beta band bilaterally in the fronto-central sensors. Moreover, all network indices can be clustered into three groups, whose exemplars are the global network efficiency, the eccentricity and the synchronizability. Again, the patterns of differences were clear: the brain network of the generalized epilepsy patients presented greater efficiency and lower eccentricity than the control subjects for the high frequency bands, without a clear topography. Besides, the frontal focal epileptic patients showed only reduced eccentricity for the theta band over fronto-temporal and central sensors. These outcomes indicate that functional epileptic brain networks are different to those of healthy subjects during interictal stage at rest, with a unique pattern of dissimilarities for each type of epilepsy. Further, when properly selected, three network indices suffice to provide a comprehensive description of these differences. Yet, since such uniqueness in the pattern of differences is also evident in the power spectrum, we conclude that the added value of the graph theory approach in this context should not be overestimated.

A new approach in the design of an interactive environment for teaching Hamiltonian digraphs

NASA Astrophysics Data System (ADS)

Iordan, A. E.; Panoiu, M.

2014-03-01

In this article the authors present the necessary steps in object orientated design of an interactive environment that is dedicated to the process of acquaintances assimilation in Hamiltonian graphs theory domain, especially for the simulation of algorithms which determine the Hamiltonian trails and circuits. The modelling of the interactive environment is achieved through specific UML diagrams representing the steps of analysis, design and implementation. This interactive environment is very useful for both students and professors, because computer programming domain, especially digraphs theory domain is comprehended and assimilated with difficulty by students.

Default contagion risks in Russian interbank market

NASA Astrophysics Data System (ADS)

Leonidov, A. V.; Rumyantsev, E. L.

2016-06-01

Systemic risks of default contagion in the Russian interbank market are investigated. The analysis is based on considering the bow-tie structure of the weighted oriented graph describing the structure of the interbank loans. A probabilistic model of interbank contagion explicitly taking into account the empirical bow-tie structure reflecting functionality of the corresponding nodes (borrowers, lenders, borrowers and lenders simultaneously), degree distributions and disassortativity of the interbank network under consideration based on empirical data is developed. The characteristics of contagion-related systemic risk calculated with this model are shown to be in agreement with those of explicit stress tests.

Proceedings of the NATO-Advanced Study Institute on Computer Aided Analysis of Rigid and Flexible Mechanical Systems Held in Troia, Portugal on 27 Jun-9 Jul, 1993. Volume 2. Contributed Papers

DTIC Science & Technology

1993-07-09

Calculate Oil and solve iteratively equation (18) for q and (l)-(S) forex . 4, Solve the velocity problemn through equation (19) to calculate q and (6)-(10) to...object.oriented models for the database to store the system information f1l. Using OOP on the formalism level is more difficult and a current field of...Multidimensional Physical Systems: Graph-theoretic Modeling, Systems and Cybernetics, vol 21 (1992), 5 .9-71 JV A RELATIONAL DATABASE FOR GENERAL

Cluster analysis in systems of magnetic spheres and cubes

NASA Astrophysics Data System (ADS)

Pyanzina, E. S.; Gudkova, A. V.; Donaldson, J. G.; Kantorovich, S. S.

2017-06-01

In the present work we use molecular dynamics simulations and graph-theory based cluster analysis to compare self-assembly in systems of magnetic spheres, and cubes where the dipole moment is oriented along the side of the cube in the [001] crystallographic direction. We show that under the same conditions cubes aggregate far less than their spherical counterparts. This difference can be explained in terms of the volume of phase space in which the formation of the bond is thermodynamically advantageous. It follows that this volume is much larger for a dipolar sphere than for a dipolar cube.

Statistical metrics for the characterization of karst network geometry and topology

NASA Astrophysics Data System (ADS)

Collon, Pauline; Bernasconi, David; Vuilleumier, Cécile; Renard, Philippe

2017-04-01

Statistical metrics can be used to analyse the morphology of natural or simulated karst systems; they allow describing, comparing, and quantifying their geometry and topology. In this paper, we present and discuss a set of such metrics. We study their properties and their usefulness based on a set of more than 30 karstic networks mapped by speleologists. The data set includes some of the largest explored cave systems in the world and represents a broad range of geological and speleogenetic conditions allowing us to test the proposed metrics, their variability, and their usefulness for the discrimination of different morphologies. All the proposed metrics require that the topographical survey of the caves are first converted to graphs consisting of vertices and edges. This data preprocessing includes several quality check operations and some corrections to ensure that the karst is represented as accurately as possible. The statistical parameters relating to the geometry of the system are then directly computed on the graphs, while the topological parameters are computed on a reduced version of the network focusing only on its structure. Among the tested metrics, we include some that were previously proposed such as tortuosity or the Howard's coefficients. We also investigate the possibility to use new metrics derived from graph theory. In total, 21 metrics are introduced, discussed in detail, and compared on the basis of our data set. This work shows that orientation analysis and, in particular, the entropy of the orientation data can help to detect the existence of inception features. The statistics on branch length are useful to describe the extension of the conduits within the network. Rather surprisingly, the tortuosity does not vary very significantly. It could be heavily influenced by the survey methodology. The degree of interconnectivity of the network, related to the presence of maze patterns, can be measured using different metrics such as the Howard's parameters, global cyclic coefficient, or the average vertex degree. The average vertex degree of the reduced graph proved to be the most useful as it is simple to compute, it discriminates properly the interconnected systems (mazes) from the acyclic ones (tree-like structures), and it permits us to classify the acyclic systems as a function of the total number of branches. This topological information is completed by three parameters, allowing us to refine the description. The correlation of vertex degree is rather simple to obtain. It is systematically positive on all studied data sets indicating a predominance of assortative networks among karst systems. The average shortest path length is related to the transport efficiency. It is shown to be mainly correlated to the size of the network. Finally, central point dominance allows us to identify the presence of a centralized organization.

Implementation and assessment of diffusion-weighted partial Fourier readout-segmented echo-planar imaging.

PubMed

Frost, Robert; Porter, David A; Miller, Karla L; Jezzard, Peter

2012-08-01

Single-shot echo-planar imaging has been used widely in diffusion magnetic resonance imaging due to the difficulties in correcting motion-induced phase corruption in multishot data. Readout-segmented EPI has addressed the multishot problem by introducing a two-dimensional nonlinear navigator correction with online reacquisition of uncorrectable data to enable acquisition of high-resolution diffusion data with reduced susceptibility artifact and T*(2) blurring. The primary shortcoming of readout-segmented EPI in its current form is its long acquisition time (longer than similar resolution single-shot echo-planar imaging protocols by approximately the number of readout segments), which limits the number of diffusion directions. By omitting readout segments at one side of k-space and using partial Fourier reconstruction, readout-segmented EPI imaging times could be reduced. In this study, the effects of homodyne and projection onto convex sets reconstructions on estimates of the fractional anisotropy, mean diffusivity, and diffusion orientation in fiber tracts and raw T(2)- and trace-weighted signal are compared, along with signal-to-noise ratio results. It is found that projections onto convex sets reconstruction with 3/5 segments in a 2 mm isotropic diffusion tensor image acquisition and 9/13 segments in a 0.9 × 0.9 × 4.0 mm(3) diffusion-weighted image acquisition provide good fidelity relative to the full k-space parameters. This allows application of readout-segmented EPI to tractography studies, and clinical stroke and oncology protocols. Copyright © 2011 Wiley-Liss, Inc.

Investigation of Carbon-Polymer Structures with Embedded Fiber-Optic Bragg Gratings

NASA Technical Reports Server (NTRS)

Grant, Joseph; Kaul, R.; Taylor, S.; Myers, G.; Sharma, A.

2003-01-01

Several Bragg-grating sensors fabricated within the same optical fiber are buried within multiple-ply carbon-epoxy planar and cylindrical structures. Effect of different orientation of fiber-sensors with respect to carbon fibers in the composite structure is investigated. This is done for both fabric and uni-tape material samples. Response of planar structures to axial and transverse strain up to 1 millistrain is investigated with distributed Bragg-grating sensors. Material properties like Young's Modulus and Poisson ratio is measured. A comparison is made between response measured by sensors in different ply-layers and those bonded on the surface. The results from buried fiber- sensors do not completely agree with surface bonded conventional strain gauges. A plausible explanation is given for observed differences. The planar structures are subjected to impacts with energies up to 10 ft-lb. Effect of this impact on the material stiffness is also investigated with buried fiber-optic Bragg sensors. The strain response of such optical sensors is also measured for cylindrical carbon-epoxy composite structures. The sensors are buried within the walls of the cylinder as well as surface bonded in both the axial as well as hoop directions. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 1500 psi. This is done at both room temperature as well as cryogenic temperatures. The recorded response is compared with that from a conventional strain gauge.

Large eddy simulation study of turbulent kinetic energy and scalar variance budgets and turbulent/non-turbulent interface in planar jets

NASA Astrophysics Data System (ADS)

Watanabe, Tomoaki; Sakai, Yasuhiko; Nagata, Koji; Ito, Yasumasa

2016-04-01

Spatially developing planar jets with passive scalar transports are simulated for various Reynolds (Re = 2200, 7000, and 22 000) and Schmidt numbers (Sc = 1, 4, 16, 64, and 128) by the implicit large eddy simulation (ILES) using low-pass filtering as an implicit subgrid-scale model. The budgets of resolved turbulent kinetic energy k and scalar variance < {φ }\\prime 2> are explicitly evaluated from the ILES data except for the dissipation terms, which are obtained from the balance in the transport equations. The budgets of k and < {φ }\\prime 2> in the ILES agree well with the DNS and experiments for both high and low Re cases. The streamwise decay of the mean turbulent kinetic energy dissipation rate obeys the power low obtained by the scaling argument. The mechanical-to-scalar timescale ratio C ϕ is evaluated in the self-similar region. For the high Re case, C ϕ is close to the isotropic value (C ϕ = 2) near the jet centerline. However, when Re is not large, C ϕ is smaller than 2 and depends on the Schmidt number. The T/NT interface is also investigated by using the scalar isosurface. The velocity and scalar fields near the interface depend on the interface orientation for all Re. The velocity toward the interface is observed near the interface facing in the streamwise, cross-streamwise, and spanwise directions in the planar jet in the resolved velocity field.

The Rock Elm meteorite impact structure, Wisconsin: Geology and shock-metamorphic effects in quartz

USGS Publications Warehouse

French, B.M.; Cordua, W.S.; Plescia, J.B.

2004-01-01

The Rock Elm structure in southwest Wisconsin is an anomalous circular area of highly deformed rocks, ???6.5 km in diameter, located in a region of virtually horizontal undeformed sedimentary rocks. Shock-produced planar microstructures (PMs) have been identified in quartz grains in several lithologies associated with the structure: sandstones, quartzite pebbles, and breccia. Two distinct types of PMs are present: P1 features, which appear identical to planar fractures (PFs or cleavage), and P2 features, which are interpreted as possible incipient planar deformation features (PDFs). The latter are uniquely produced by the shock waves associated with meteorite impact events. Both types of PMs are oriented parallel to specific crystallographic planes in the quartz, most commonly to c(0001), ??112??2, and r/z101??1. The association of unusual, structurally deformed strata with distinct shock-produced microdeformation features in their quartz-bearing rocks establishes Rock Elm as a meteorite impact structure and supports the view that the presence of multiple parallel cleavages in quartz may be used independently as a criterion for meteorite impact. Preliminary paleontological studies indicate a minimum age of Middle Ordovician for the Rock Elm structure. A similar age estimate (450-400 Ma) is obtained independently by combining the results of studies of the general morphology of complex impact structures with estimated rates of sedimentation for the region. Such methods may be applicable to dating other old and deeply eroded impact structures formed in sedimentary target rocks.

Controllable Growth of Perovskite Films by Room-Temperature Air Exposure for Efficient Planar Heterojunction Photovoltaic Cells.

PubMed

Yang, Bin; Dyck, Ondrej; Poplawsky, Jonathan; Keum, Jong; Das, Sanjib; Puretzky, Alexander; Aytug, Tolga; Joshi, Pooran C; Rouleau, Christopher M; Duscher, Gerd; Geohegan, David B; Xiao, Kai

2015-12-01

A two-step solution processing approach has been established to grow void-free perovskite films for low-cost high-performance planar heterojunction photovoltaic devices. A high-temperature thermal annealing treatment was applied to drive the diffusion of CH3NH3I precursor molecules into a compact PbI2 layer to form perovskite films. However, thermal annealing for extended periods led to degraded device performance owing to the defects generated by decomposition of perovskite into PbI2. A controllable layer-by-layer spin-coating method was used to grow "bilayer" CH3NH3I/PbI2 films, and then drive the interdiffusion between PbI2 and CH3NH3I layers by a simple air exposure at room temperature for making well-oriented, highly crystalline perovskite films without thermal annealing. This high degree of crystallinity resulted in a carrier diffusion length of ca. 800 nm and a high device efficiency of 15.6%, which is comparable to values reported for thermally annealed perovskite films. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The invariant cleavage pattern displayed by ascidian embryos depends on spindle positioning along the cell's longest axis in the apical plane and relies on asynchronous cell divisions

PubMed Central

Dumollard, Rémi; Minc, Nicolas; Salez, Gregory; Aicha, Sameh Ben; Bekkouche, Faisal; Hebras, Céline; Besnardeau, Lydia; McDougall, Alex

2017-01-01

The ascidian embryo is an ideal system to investigate how cell position is determined during embryogenesis. Using 3D timelapse imaging and computational methods we analyzed the planar cell divisions in ascidian early embryos and found that spindles in every cell tend to align at metaphase in the long length of the apical surface except in cells undergoing unequal cleavage. Furthermore, the invariant and conserved cleavage pattern of ascidian embryos was found to consist in alternate planar cell divisions between ectoderm and endomesoderm. In order to test the importance of alternate cell divisions we manipulated zygotic transcription induced by β-catenin or downregulated wee1 activity, both of which abolish this cell cycle asynchrony. Crucially, abolishing cell cycle asynchrony consistently disrupted the spindle orienting mechanism underpinning the invariant cleavage pattern. Our results demonstrate how an evolutionary conserved cell cycle asynchrony maintains the invariant cleavage pattern driving morphogenesis of the ascidian blastula. DOI: http://dx.doi.org/10.7554/eLife.19290.001 PMID:28121291

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolotin, B. M., E-mail: bolotin70@yandex.ru; Mikhlina, Ya. A.; Arkhipova, S. A.

The crystal and molecular structures of two crystal forms (pale yellow form 1 and yellow form 2) of N-[2-(4-oxo-4H-benzo[d][1,3]oxazin-2-yl)phenyl]naphthalene-2-sulfonamide (Orlyum White 520T), which is an organic luminophore with an anomalously high Stokes shift, were determined. Crystal 2 is a solvate with para-xylene. Crystal 1 is a solvent-free form. The molecular geometry in crystal 1 differs from that in 2 only in the orientation of the SO{sub 2}Ar substituent. The bond-length distribution in the planar moiety of the molecule in crystal 1 is virtually identical to that in 2, but the bonds in the NH-SO{sub 2}Ar-bearing benzene ring in crystal 1more » are systematically longer than the corresponding bonds in crystal 2. This fact can be attributed to the crystal-packing effects. In 2 the molecules form stacked dimers with {pi}-stacking interactions between two planar conjugated tricyclic systems. The charge transfer in this system accounts for the intensification of the color of these crystals and the observed difference in the optical properties of 1 and 2.« less

Van der Waals interactions between planar substrate and tubular lipid membranes undergoing pearling instability

NASA Astrophysics Data System (ADS)

Valchev, G. S.; Djondjorov, P. A.; Vassilev, V. M.; Dantchev, D. M.

2017-10-01

In the current article we study the behavior of the van der Waals force between a planar substrate and an axisymmetric bilayer lipid membrane undergoing pearling instability, caused by uniform hydrostatic pressure difference. To do so, the recently suggested "surface integration approach" is used, which can be considered a generalization of the well known and widely used Derjaguin approximation. The static equilibrium shape after the occurrence of the instability is described in the framework of Helfrich's spontaneous curvature model. Some specific classes of exact analytical solutions to the corresponding shape equation are considered, and the components of the respective position vectors given in terms of elliptic integrals and Jacobi elliptic functions. The mutual orientation between the interacting objects is chosen such that the axis of revolution of the distorted cylinder be parallel to the plane bounding the substrate. Based on the discussed models and approaches we made some estimations for the studied force in real experimentally realizable systems, thus showing the possibility of pearling as an useful technique for reduction of the adhesion in variety of industrial processes using lipid membranes as carriers.

Molecular Dynamics Study of High Symmetry Planar Defect Evolution during Growth of CdTe/CdS Films

DOE PAGES

Chavez, Jose Juan; Zhou, Xiao W.; Almeida, Sergio F.; ...

2017-12-15

The growth dynamics and evolution of intrinsic stacking faults, lamellar, and double positioning twin grain boundaries were explored using molecular dynamics simulations during the growth of CdTe homoepitaxy and CdTe/CdS heteroepitaxy. Initial substrate structures were created containing either stacking fault or one type of twin grain boundary, and films were subsequently deposited to study the evolution of the underlying defect. Results show that during homoepitaxy the film growth was epitaxial and the substrate’s defects propagated into the epilayer, except for the stacking fault case where the defect disappeared after the film thickness increased. In contrast, films grown on heteroepitaxy conditionsmore » formed misfit dislocations and grew with a small angle tilt (within ~5°) of the underlying substrate’s orientation to alleviate the lattice mismatch. Grain boundary proliferation was observed in the lamellar and double positioning twin cases. Finally, our study indicates that it is possible to influence the propagation of high symmetry planar defects by selecting a suitable substrate defect configuration, thereby controlling the film defect morphology.« less

Molecular Dynamics Study of High Symmetry Planar Defect Evolution during Growth of CdTe/CdS Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chavez, Jose Juan; Zhou, Xiao W.; Almeida, Sergio F.

The growth dynamics and evolution of intrinsic stacking faults, lamellar, and double positioning twin grain boundaries were explored using molecular dynamics simulations during the growth of CdTe homoepitaxy and CdTe/CdS heteroepitaxy. Initial substrate structures were created containing either stacking fault or one type of twin grain boundary, and films were subsequently deposited to study the evolution of the underlying defect. Results show that during homoepitaxy the film growth was epitaxial and the substrate’s defects propagated into the epilayer, except for the stacking fault case where the defect disappeared after the film thickness increased. In contrast, films grown on heteroepitaxy conditionsmore » formed misfit dislocations and grew with a small angle tilt (within ~5°) of the underlying substrate’s orientation to alleviate the lattice mismatch. Grain boundary proliferation was observed in the lamellar and double positioning twin cases. Finally, our study indicates that it is possible to influence the propagation of high symmetry planar defects by selecting a suitable substrate defect configuration, thereby controlling the film defect morphology.« less

High field superconducting properties of Ba(Fe1-xCox)2As2 thin films

NASA Astrophysics Data System (ADS)

Hänisch, Jens; Iida, Kazumasa; Kurth, Fritz; Reich, Elke; Tarantini, Chiara; Jaroszynski, Jan; Förster, Tobias; Fuchs, Günther; Hühne, Ruben; Grinenko, Vadim; Schultz, Ludwig; Holzapfel, Bernhard

2015-11-01

In general, the critical current density, Jc, of type II superconductors and its anisotropy with respect to magnetic field orientation is determined by intrinsic and extrinsic properties. The Fe-based superconductors of the ‘122’ family with their moderate electronic anisotropies and high yet accessible critical fields (Hc2 and Hirr) are a good model system to study this interplay. In this paper, we explore the vortex matter of optimally Co-doped BaFe2As2 thin films with extended planar and c-axis correlated defects. The temperature and angular dependence of the upper critical field is well explained by a two-band model in the clean limit. The dirty band scenario, however, cannot be ruled out completely. Above the irreversibility field, the flux motion is thermally activated, where the activation energy U0 is going to zero at the extrapolated zero-kelvin Hirr value. The anisotropy of the critical current density Jc is both influenced by the Hc2 anisotropy (and therefore by multi-band effects) as well as the extended planar and columnar defects present in the sample.

Planar cell polarity signaling in the uterus directs appropriate positioning of the crypt for embryo implantation

PubMed Central

Yuan, Jia; Cha, Jeeyeon; Deng, Wenbo; Bartos, Amanda; Sun, Xiaofei; Ho, Hsin-Yi Henry; Borg, Jean-Paul; Yamaguchi, Terry P.; Yang, Yingzi; Dey, Sudhansu K.

2016-01-01

Blastocyst implantation is a complex process requiring coordination of a dynamic sequence of embryo–uterine interactions. Blood vessels enter the uterus from the mesometrium, demarcating the uterus into mesometrial (M) and antimesometrial (AM) domains. Implantation occurs along the uterine longitudinal axis within specialized implantation chambers (crypts) that originate within the evaginations directed from the primary lumen toward the AM domain. The morphological orientation of crypts in rodent uteri was recognized more than a century ago, but the mechanism remained unknown. Here we provide evidence that planar cell polarity (PCP) signaling orchestrates directed epithelial evaginations to form crypts for implantation in mice. Uterine deletion of Vang-like protein 2, but not Vang-like protein 1, conferred aberrant PCP signaling, misdirected epithelial evaginations, defective crypt formation, and blastocyst attachment, leading to severely compromised pregnancy outcomes. The study reveals a previously unrecognized role for PCP in executing spatial cues for crypt formation and implantation. Because PCP is an evolutionarily conserved phenomenon, our study is likely to inspire implantation studies of this signaling pathway in humans and other species. PMID:27911818

Optical and Structural Properties of Microcrystalline GaN on an Amorphous Substrate Prepared by a Combination of Molecular Beam Epitaxy and Metal-Organic Chemical Vapor Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Min, Jung-Wook; Hwang, Hyeong-Yong; Kang, Eun-Kyu

2016-05-01

Microscale platelet-shaped GaN grains were grown on amorphous substrates by a combined epitaxial growth method of molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD). First, MBE GaN was grown on an amorphous substrate as a pre-orienting layer and its structural properties were investigated. Second, MOCVD grown GaN samples using the different growth techniques of planar and selective area growth (SAG) were comparatively investigated by transmission electron microscopy (TEM), cathodoluminescence (CL), and photoluminescence (PL). In MOCVD planar GaN, strong bound exciton peaks dominated despite the high density of the threading dislocations (TDs). In MOCVD SAG GaN, on the othermore » hand, TDs were clearly reduced with bending, but basal stacking fault (BSF) PL peaks were observed at 3.42 eV. The combined epitaxial method not only provides a deep understanding of the growth behavior but also suggests an alternative approach for the growth of GaN on amorphous substances.« less

High-temperature superconducting radiofrequency probe for magnetic resonance imaging applications operated below ambient pressure in a simple liquid-nitrogen cryostat

NASA Astrophysics Data System (ADS)

Lambert, Simon; Ginefri, Jean-Christophe; Poirier-Quinot, Marie; Darrasse, Luc

2013-05-01

The present work investigates the joined effects of temperature and static magnetic field on the electrical properties of a 64 MHz planar high-temperature superconducting (HTS) coil, in order to enhance the signal-to-noise ratio (SNR) in nuclear magnetic resonance (NMR) applications with a moderate decrease of the HTS coil temperature (THTS). Temperature control is provided with accuracy better than 0.1 K from 80 to 66 K by regulating the pressure of the liquid nitrogen bath of a dedicated cryostat. The actual temperature of the HTS coil is obtained using a straightforward wireless method that eliminates the risks of coupling electromagnetic interference to the HTS coil and of disturbing the static magnetic field by DC currents near the region of interest. The resonance frequency ( f0) and the quality factor (Q) of the HTS coil are measured as a function of temperature in the 0-4.7 T field range with parallel and orthogonal orientations relative to the coil plane. The intrinsic HTS coil sensitivity and the detuning effect are then analyzed from the Q and f0 data. In the presence of the static magnetic field, the initial value of f0 in Earth's field could be entirely recovered by decreasing THTS, except for the orthogonal orientation above 1 T. The improvement of Q by lowering THTS was substantial. From 80 to 66 K, Q was multiplied by a factor of 6 at 1.5 T in orthogonal orientation. In parallel orientation, the maximum measured improvement of Q from 80 K to 66 K was a factor of 2. From 80 to 66 K, the improvement of the RF sensitivity relative to the initial value at the Earth's field and ambient pressure was up to 4.4 dB in parallel orientation. It was even more important in orthogonal orientation and continued to increase, up to 8.4 dB, at the maximum explored field of 1.5 T. Assuming that the noise contributions from the RF receiver are negligible, the SNR improvement using enhanced HTS coil cooling in NMR experiments was extracted from Q measurements either with or without the presence of the sample. Notably, the additional cooling in the presence of conductive samples appears more beneficial at higher field strengths and with an orthogonal incidence than with parallel. The temperature range accessible here, involving a relatively straightforward cryogenic design, brings a gain in RF sensitivity that is of great significance to cutting-edge applications with very weakly conducting samples, small biological specimens, or small animals in vivo. This work also demonstrates a better tolerance to thin-film orientation misalignments relative to the magnetic field, and this could eventually play a role in designing effective non-planar HTS coils or coil arrays which include elements of various orientations. Finally, the data provided in this work may help understand some critical aspects in the design of HTS coils for NMR and MRI applications and accounts for the presence of the static magnetic field, particularly regarding the SNR loss due to a decreased quality factor and detuning issues.

Graph-based impact analysis as a framework for incorporating practitioner knowledge in dairy herd health management.

PubMed

Krieger, M; Schwabenbauer, E-M; Hoischen-Taubner, S; Emanuelson, U; Sundrum, A

2018-03-01

Production diseases in dairy cows are multifactorial, which means they emerge from complex interactions between many different farm variables. Variables with a large impact on production diseases can be identified for groups of farms using statistical models, but these methods cannot be used to identify highly influential variables in individual farms. This, however, is necessary for herd health planning, because farm conditions and associated health problems vary largely between farms. The aim of this study was to rank variables according to their anticipated effect on production diseases on the farm level by applying a graph-based impact analysis on 192 European organic dairy farms. Direct impacts between 13 pre-defined variables were estimated for each farm during a round-table discussion attended by practitioners, that is farmer, veterinarian and herd advisor. Indirect impacts were elaborated through graph analysis taking into account impact strengths. Across farms, factors supposedly exerting the most influence on production diseases were 'feeding', 'hygiene' and 'treatment' (direct impacts), as well as 'knowledge and skills' and 'herd health monitoring' (indirect impacts). Factors strongly influenced by production diseases were 'milk performance', 'financial resources' and 'labour capacity' (directly and indirectly). Ranking of variables on the farm level revealed considerable differences between farms in terms of their most influential and most influenced farm factors. Consequently, very different strategies may be required to reduce production diseases in these farms. The method is based on perceptions and estimations and thus prone to errors. From our point of view, however, this weakness is clearly outweighed by the ability to assess and to analyse farm-specific relationships and thus to complement general knowledge with contextual knowledge. Therefore, we conclude that graph-based impact analysis represents a promising decision support tool for herd health planning. The next steps include testing the method using more specific and problem-oriented variables as well as evaluating its effectiveness.

Optically tracked, single-coil, scanning magnetic induction tomography

NASA Astrophysics Data System (ADS)

Feldkamp, Joe R.; Quirk, Stephen

2017-03-01

Recent work has shown the feasibility of single-coil, magnetic induction tomography, for visualizing a 3D distribution of electrical conductivity in portions of the human body. Loss is measured in a single, planar coil consisting of concentric circular loops while the coil is relocated to various non-redundant positions and orientations in the vicinity of the target. These loss values, together with measured coil position and orientation, are processed by a quantitative mapping equation that enables reconstruction of an electrical conductivity image. Up until now, the position of the coil had to be established by a template, which required assignment of locations for the coil to visit without necessarily giving any prior consideration to target geometry. We have now added optical tracking to our existing single-coil device so that position and orientation are tracked automatically, allowing collection of coil loss data at arbitrary positions or orientations as needed. Optical tracking is accomplished via a set of IR reflective spheres mounted on the same enclosure that supports the coil. Position for a select sphere within the set, together with the four quaternions specifying optical body orientation, is fed to a laptop at the same time coil loss data is streamed to the same laptop via Bluetooth. The coil center can be tracked with sub-millimeter accuracy while orientation angle is known to a fraction of a degree. This work illustrates the use of single-coil MIT in full, position-orientation-tracked scan mode while imaging laboratory phantoms. Phantoms are based upon simple materials having biologic conductivity (< 5 S/m), including a cut of bone-in steak. The goal is not just to reconstruct an image that contains the features of the actual target, but also return correct conductivity values for the various features within the image.

Experimental Method for Characterizing Electrical Steel Sheets in the Normal Direction

PubMed Central

Hihat, Nabil; Lecointe, Jean Philippe; Duchesne, Stephane; Napieralska, Ewa; Belgrand, Thierry

2010-01-01

This paper proposes an experimental method to characterise magnetic laminations in the direction normal to the sheet plane. The principle, which is based on a static excitation to avoid planar eddy currents, is explained and specific test benches are proposed. Measurements of the flux density are made with a sensor moving in and out of an air-gap. A simple analytical model is derived in order to determine the permeability in the normal direction. The experimental results for grain oriented steel sheets are presented and a comparison is provided with values obtained from literature. PMID:22163394

Emergent propagation modes of ferromagnetic swimmers in constrained geometries

NASA Astrophysics Data System (ADS)

Bryan, M. T.; Shelley, S. R.; Parish, M. J.; Petrov, P. G.; Winlove, C. P.; Gilbert, A. D.; Ogrin, F. Y.

2017-02-01

Magnetic microswimmers, composed of hard and soft ferromagnets connected by an elastic spring, are modelled under low Reynolds number conditions in the presence of geometrical boundaries. Approaching a surface, the magneto-elastic swimmer's velocity increases and its trajectory bends parallel to the surface contour. Further confinement to form a planar channel generates new propagation modes as the channel width narrows, altering the magneto-elastic swimmer's speed, orientation, and direction of travel. Our results demonstrate that constricted geometric environments, such as occuring in microfluidic channels or blood vessels, may influence the functionality of magneto-elastic microswimmers for applications such as drug delivery.

Crystal structure of 2-oxopyrrolidin-3-yl 4-(2-phenyl-diazen-1-yl)benzoate.

PubMed

Elkin, Igor; Maris, Thierry; Melkoumov, Alexandre; Hildgen, Patrice; Banquy, Xavier; Leclair, Grégoire; Barrett, Christopher

2018-04-01

In the title compound, C 17 H 15 N 3 O 3 , the plane of the pyrrolidone ring is inclined at an angle of 59.791 (2)° to that of the azo-benzene segment, which adopts a configuration close to planar. In the crystal, mol-ecules are oriented pairwise by (2-oxopyrrolidin-3-yl)-oxy moieties at an angle of 76.257 (3)°, linked by hydrogen bonds and π-stacking inter-actions, forming zigzag supra-molecular chains parallel to [010] further linked via additional C-H⋯π inter-actions.

7-Chloro-5-(2-ethoxy­phen­yl)-1-methyl-3-propyl-2,6-dihydro-1H-pyrazolo[4,3-d]pyrimidine

PubMed Central

Zhou, Ming-Qiu; Zhu, Kai; Lv, Xiao-Ping; Han, Ping-Fang; Wei, Ping

2009-01-01

In the title compound, C17H21ClN4O, the benzene ring is oriented at dihedral angles of 1.59 (3) and 1.27 (3)° with respect to the pyrimidine and pyrazole rings, while the dihedral angle between the pyrimidine and pyrazole rings is 0.83 (3)°. An intra­molecular N—H⋯O hydrogen bond results in the formation of a planar (r.m.s. deviation 0.004 Å) six-membered ring. PMID:21577789

Development of Nomarski microscopy for quantitative determination of surface topography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartman, J. S.; Gordon, R. L.; Lessor, D. L.

1979-01-01

The use of Nomarski differential interference contrast (DIC) microscopy has been extended to provide nondestructive, quantitative analysis of a sample's surface topography. Theoretical modeling has determined the dependence of the image intensity on the microscope's optical components, the sample's optical properties, and the sample's surface orientation relative to the microscope. Results include expressions to allow the inversion of image intensity data to determine sample surface slopes. A commercial Nomarski system has been modified and characterized to allow the evaluation of the optical model. Data have been recorded with smooth, planar samples that verify the theoretical predictions.

Curved cap corrugated sheet

NASA Technical Reports Server (NTRS)

Davis, R. C.; Bales, T. T.; Royster, D. M.; Jackson, L. R. (Inventor)

1984-01-01

The report describes a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation with a part-cylindrical crown and cap strip, and straight side walls and with secondary corrugations oriented at right angles to said side walls. The cap strip is bonded to the crown and the longitudinal edge of said cap strip extends beyond edge at the intersection between said crown and said side walls. The high strength relative to weight of the structure makes it desirable for use in aircraft or spacecraft.

Benzil bis-(ketazine).

PubMed

Patra, Goutam Kumar; Mukherjee, Anindita; Ng, Seik Weng

2009-07-04

1,1',2,2'-tetra-phenyl-2,2'-azinodiethanone), C(28)H(20)N(2)O(2), was obtained by the reaction of benzil monohydrazone with chromium(III) nitrate. The dibenzyl-idene hydrazine unit is nearly planar (r.m.s. deviation = 0.073 Å) and the two benzoyl units are oriented almost perpendicular to it [dihedral angle = 87.81 (2), 87.81 (2)°]. The mol-ecules are linked into chains along the c axis by C-H⋯O hydrogen bonds and the chains are cross-linked via C-H⋯π inter-actions involving the benzoyl phenyl rings.

Quartz microstructures in the Younger Dryas boundary layer ~12.9 ka.

NASA Astrophysics Data System (ADS)

van Hoesel, A.; Hoek, W. Z.; Pennock, G. M.; Drury, M. R.

2012-04-01

In 2007, Firestone et al. proposed that an extraterrestrial impact occurred at the end of the Allerød interstadial, destabilizing the North American ice sheet and initiating the colder Younger Dryas (YD) stadial. Up to now, the evidence for this proposed impact has been heavily debated (Pinter et al., 2011) and no one has been able to provide convincing evidence in favour of the hypothesis. Two years later, Mahaney et al. (2009) claimed that they had frequently found planar deformation features (PDFs) in quartz from a possible YD boundary layer in Venezuela. However, the data presented consisted of an SEM image of the surface of a quartz grain only, and in following work Mahaney et al. (2010) stated that they had found no irrefutable evidence of PDFs. Instead, they showed grains with oriented cracks along their edges, which they claimed to be related to the 'mass impact and extreme heat' from incoming ejecta material. However, oriented cracks are not accepted evidence for an impact (French, Koeberl, 2010). We investigate the quartz fraction of samples from the European Usselo horizon, an Allerød-YD age soil, as well as one sample from the North American Black Mat, which marks the onset of the YD. Possible shocked quartz grains were isolated using density separation, mounted in epoxy and polished. No evidence for oriented cracks along grain edges, like those reported by Mahaney et al. (2010), has been found so far. Transmitted light microscopy showed that a number of grains contained tectonic deformation lamellae. One grain from the Usselo horizon contains at least two sets of closely spaced, straight, and narrow lamellae, similar to PDFs. In SEM-CL imaging however, only some of these lamellae showed up as non-luminescent, while most had the same intensity as the host grain. This is not typical for PDFs (Hamers, Drury 2011). It is possible that these lamellae represent planar fractures, which also form by low pressure shock processes. It must be noted that even if these closely spaced features are indeed shock related, one or two grains do not prove the YD impact hypothesis. Although, the quartz in the YD boundary layer is derived from regional aeolian activity, their source material was transported to the area by major rivers systems or the Scandinavian ice sheet. It is thus possible that these grains were eroded from an older crater or impact horizon. Furthermore, low shock level deformation might also occur during a large volcanic eruption. In that case, the planar features we find might possibly be related to the colossal Laacher See eruption (Van den Bogaard, Schminke, 1985), which occurred only two centuries before the onset of the YD.

Validation of the relative 3D orientation of vertebrae reconstructed by bi-planar radiography.

PubMed

Dumas, R; Le Bras, A; Champain, N; Savidan, M; Mitton, D; Kalifa, G; Steib, J-P; de Guise, J A; Skalli, W

2004-06-01

The three dimensional (3D) reconstruction of the spine can be obtained by stereoradiographic techniques. To be safely used on a routine clinics basis, stereoradiography must provide both accurate vertebral shape and coherent position. Although the accuracy of the reconstructed morphology of the vertebrae is well documented, only few authors studied the accuracy of the vertebral orientation. Therefore, this paper focuses on the evaluation of the orientation accuracy of the reconstructed vertebrae (obtained by non-stereo corresponding point technique) considering either a 178 point vertebral model or a 6 point vertebral model (previously proposed in the literature). Five dried vertebrae were fixed on holders containing four markers each. The 3D reconstruction of both vertebrae and markers were obtained by stereoradiographic techniques. Using least square method matching from one position to another, the relative orientation was computed for the vertebral models (6 or 178 points) and the four markers. These vertebral and holder orientations were compared (considering the holder's one as reference). The repeatability of these relative orientations (vertebrae and holders) was also evaluated. The mean (RMS) orientation error of 178 point vertebral model was 0.6 degrees (0.8 degrees ), for lateral rotation, 0.7 degrees (1.0 degrees ) for sagittal rotation and 1.4 degrees (1.9 degrees ) for axial rotation. The intra-observer repeatability was 0.5 degrees (0.7 degrees ) for lateral rotation, 0.7 degrees (0.8 degrees ) for sagittal rotation and 0.9 degrees (1.2 degrees ) for axial rotation. The orientation was found more accurate and precise when using the 178 point vertebral model than when using the basic 6 point vertebral model. The relative orientation (in post-operative follow-up with respect to the pre-operative examination) of the vertebrae of one scoliotic patient was performed as an example of clinical application. The stereoradiographic method is a reliable 3D quantitative tool to assess the spine deformity, that can be used in clinics for the follow-up of scoliotic patients.

Magnetic and clast fabrics as measurements of grain-scale processes within the Death Valley shallow crustal detachment faults

NASA Astrophysics Data System (ADS)

Hayman, Nicholas W.; Housen, B. A.; Cladouhos, T. T.; Livi, K.

2004-05-01

The rock product of shallow-crustal faulting includes fine-grained breccia and clay-rich gouge. Many gouges and breccias have a fabric produced by distributed deformation. The orientation of fabric elements provides constraints on the kinematics of fault slip and is the structural record of intrafault strain not accommodated by planar and penetrative surfaces. However, it can be difficult to quantify the deformational fabric of fault rocks, especially the preferred orientations of fine-grained minerals, or to uniquely determine the relationship between fabric geometry and finite strain. Here, we present the results of a fabric study of gouge and breccia sampled from low-angle normal (detachment) faults in the Black Mountains, Death Valley, CA. We measured a preferred orientation of the long axes of the clasts inherited from the crystalline footwall of the fault and compared the shape preferred orientation to the anisotropy of magnetic susceptibility of the fault rocks. The two measurements of fabric exhibit systematic similarities and differences in orientation and anisotropy that are compatible with the large-scale kinematics of fault slip. The dominant carriers of the magnetic susceptibility are micron- and sub-micron scale iron oxides and clay minerals. Therefore even the finest grains in the fault rock were sensitive to the distributed deformation and the micro-mechanics of particle interaction must have departed from those assumed by the passive-marker kinematic model that best explains the fabric.

Effects of Orientation and Anisometry of Magnetic Resonance Imaging Acquisitions on Diffusion Tensor Imaging and Structural Connectomes.

PubMed

Tudela, Raúl; Muñoz-Moreno, Emma; López-Gil, Xavier; Soria, Guadalupe

2017-01-01

Diffusion-weighted imaging (DWI) quantifies water molecule diffusion within tissues and is becoming an increasingly used technique. However, it is very challenging as correct quantification depends on many different factors, ranging from acquisition parameters to a long pipeline of image processing. In this work, we investigated the influence of voxel geometry on diffusion analysis, comparing different acquisition orientations as well as isometric and anisometric voxels. Diffusion-weighted images of one rat brain were acquired with four different voxel geometries (one isometric and three anisometric in different directions) and three different encoding orientations (coronal, axial and sagittal). Diffusion tensor scalar measurements, tractography and the brain structural connectome were analyzed for each of the 12 acquisitions. The acquisition direction with respect to the main magnetic field orientation affected the diffusion results. When the acquisition slice-encoding direction was not aligned with the main magnetic field, there were more artifacts and a lower signal-to-noise ratio that led to less anisotropic tensors (lower fractional anisotropic values), producing poorer quality results. The use of anisometric voxels generated statistically significant differences in the values of diffusion metrics in specific regions. It also elicited differences in tract reconstruction and in different graph metric values describing the brain networks. Our results highlight the importance of taking into account the geometric aspects of acquisitions, especially when comparing diffusion data acquired using different geometries.

Frizzled Receptors in Development and Disease

PubMed Central

Wang, Yanshu; Chang, Hao; Rattner, Amir; Nathans, Jeremy

2016-01-01

Frizzled proteins are the principal receptors for the Wnt family of ligands. They mediate canonical Wnt signaling together with Lrp5 and Lrp6 coreceptors. In conjunction with Celsr, Vangl, and a small number of additional membrane and membrane-associated proteins, they also play a central role in tissue polarity/planar cell polarity (PCP) signaling. Targeted mutations in 9 of the 10 mammalian Frizzled genes have revealed their roles in an extraordinarily diverse set of developmental and homeostatic processes, including morphogenetic movements responsible for palate, ventricular septum, ocular furrow, and neural tube closure; survival of thalamic neurons; bone formation; central nervous system (CNS) angiogenesis and blood–brain barrier formation and maintenance; and a wide variety of processes that orient subcellular, cellular, and multicellular structures relative to the body axes. The last group likely reflects the mammalian equivalent of tissue polarity/PCP signaling, as defined in Drosophila, and it includes CNS axon guidance, hair follicle and tongue papilla orientation, and inner ear sensory hair bundle orientation. Frizzled receptors are ubiquitous among multicellular animals and, with other signaling molecules, they very likely evolved to permit the development of the complex tissue architectures that provide multicellular animals with their enormous selective advantage. PMID:26969975

Correlation between polymer architecture, mesoscale structure and photovoltaic performance in side-chain-modified PAE-PAV:fullerene bulk-heterojunction solar cells

NASA Astrophysics Data System (ADS)

Rathgeber, S.; Kuehnlenz, F.; Hoppe, H.; Egbe, D. A. M.; Tuerk, S.; Perlich, J.; Gehrke, R.

2012-02-01

A poly(arylene-ethynylene)-alt-poly(arylene-vinylene) statistical copolymer carrying linear and branched alkoxy side chains along the conjugated backbone in a random manner, yields, compared to its regular substituted counterparts, an improved performance in polymer:fullerene bulk-heterojunction solar cells. Results obtained from GiWAXS experiments show that the improved performance of the statistical copolymer may be attributed to the following structural characteristics: 1) Well, ordered stacked domains that promote backbone planarization and thus improve the ππ-overlap. 2) Partly face-on alignment of domains relative to the electrodes for an improved active layer electrode charge transfer. Branched side chains seem to promote face-on domain orientation. Most likely they can minimize their unfavorable contact with the interface by just bringing the CH3 groups of the branches into direct contact with the surface so that favorable phenylene-substrate interaction can promote face-on orientation. 3) A more isotropic domain orientation throughout the active layer to ensure that the backbone alignment direction has components perpendicular and parallel to the electrodes in order to compromise between light absorption and efficient intra-chain charge transport.

The elastic ratio: introducing curvature into ratio-based image segmentation.

PubMed

Schoenemann, Thomas; Masnou, Simon; Cremers, Daniel

2011-09-01

We present the first ratio-based image segmentation method that allows imposing curvature regularity of the region boundary. Our approach is a generalization of the ratio framework pioneered by Jermyn and Ishikawa so as to allow penalty functions that take into account the local curvature of the curve. The key idea is to cast the segmentation problem as one of finding cyclic paths of minimal ratio in a graph where each graph node represents a line segment. Among ratios whose discrete counterparts can be globally minimized with our approach, we focus in particular on the elastic ratio [Formula: see text] that depends, given an image I, on the oriented boundary C of the segmented region candidate. Minimizing this ratio amounts to finding a curve, neither small nor too curvy, through which the brightness flux is maximal. We prove the existence of minimizers for this criterion among continuous curves with mild regularity assumptions. We also prove that the discrete minimizers provided by our graph-based algorithm converge, as the resolution increases, to continuous minimizers. In contrast to most existing segmentation methods with computable and meaningful, i.e., nondegenerate, global optima, the proposed approach is fully unsupervised in the sense that it does not require any kind of user input such as seed nodes. Numerical experiments demonstrate that curvature regularity allows substantial improvement of the quality of segmentations. Furthermore, our results allow drawing conclusions about global optima of a parameterization-independent version of the snakes functional: the proposed algorithm allows determining parameter values where the functional has a meaningful solution and simultaneously provides the corresponding global solution.

Optimal perturbations for nonlinear systems using graph-based optimal transport

NASA Astrophysics Data System (ADS)

Grover, Piyush; Elamvazhuthi, Karthik

2018-06-01

We formulate and solve a class of finite-time transport and mixing problems in the set-oriented framework. The aim is to obtain optimal discrete-time perturbations in nonlinear dynamical systems to transport a specified initial measure on the phase space to a final measure in finite time. The measure is propagated under system dynamics in between the perturbations via the associated transfer operator. Each perturbation is described by a deterministic map in the measure space that implements a version of Monge-Kantorovich optimal transport with quadratic cost. Hence, the optimal solution minimizes a sum of quadratic costs on phase space transport due to the perturbations applied at specified times. The action of the transport map is approximated by a continuous pseudo-time flow on a graph, resulting in a tractable convex optimization problem. This problem is solved via state-of-the-art solvers to global optimality. We apply this algorithm to a problem of transport between measures supported on two disjoint almost-invariant sets in a chaotic fluid system, and to a finite-time optimal mixing problem by choosing the final measure to be uniform. In both cases, the optimal perturbations are found to exploit the phase space structures, such as lobe dynamics, leading to efficient global transport. As the time-horizon of the problem is increased, the optimal perturbations become increasingly localized. Hence, by combining the transfer operator approach with ideas from the theory of optimal mass transportation, we obtain a discrete-time graph-based algorithm for optimal transport and mixing in nonlinear systems.

Registration of 3D spectral OCT volumes combining ICP with a graph-based approach

NASA Astrophysics Data System (ADS)

Niemeijer, Meindert; Lee, Kyungmoo; Garvin, Mona K.; Abràmoff, Michael D.; Sonka, Milan

2012-02-01

The introduction of spectral Optical Coherence Tomography (OCT) scanners has enabled acquisition of high resolution, 3D cross-sectional volumetric images of the retina. 3D-OCT is used to detect and manage eye diseases such as glaucoma and age-related macular degeneration. To follow-up patients over time, image registration is a vital tool to enable more precise, quantitative comparison of disease states. In this work we present a 3D registrationmethod based on a two-step approach. In the first step we register both scans in the XY domain using an Iterative Closest Point (ICP) based algorithm. This algorithm is applied to vessel segmentations obtained from the projection image of each scan. The distance minimized in the ICP algorithm includes measurements of the vessel orientation and vessel width to allow for a more robust match. In the second step, a graph-based method is applied to find the optimal translation along the depth axis of the individual A-scans in the volume to match both scans. The cost image used to construct the graph is based on the mean squared error (MSE) between matching A-scans in both images at different translations. We have applied this method to the registration of Optic Nerve Head (ONH) centered 3D-OCT scans of the same patient. First, 10 3D-OCT scans of 5 eyes with glaucoma imaged in vivo were registered for a qualitative evaluation of the algorithm performance. Then, 17 OCT data set pairs of 17 eyes with known deformation were used for quantitative assessment of the method's robustness.

Microcomputed tomography and shock microdeformation studies on shatter cones

NASA Astrophysics Data System (ADS)

Zaag, Patrice Tristan; Reimold, Wolf Uwe; Hipsley, Christy Anna

2016-08-01

One of the aspects of impact cratering that are still not fully understood is the formation of shatter cones and related fracturing phenomena. Yet, shatter cones have been applied as an impact-diagnostic criterion for decades without the role of shock waves and target rock defects in their formation having been elucidated ever. We have tested the application of the nondestructive microcomputed tomography (μCT) method to visualize the interior of shatter cones in order to possibly resolve links between fracture patterns and shatter cone surface features (striations and intervening "valleys"). Shatter-coned samples from different impact sites and in different lithologies were investigated for their μCT suitability, with a shatter cone in sandstone from the Serra da Cangalha impact structure (Brazil) remaining as the most promising candidate because of the fracture resolution achieved. To validate the obtained CT data, the scanned specimen was cut into three orthogonal sets of thin sections. Scans with 13 μm resolution were obtained. μCT scans and microscopic analysis unraveled an orientation of subplanar fractures and related fluid inclusion trails, and planar fracture (PF) orientations in the interior of shatter cones. Planar deformation features (PDF) were observed predominantly near the shatter cone surface. Previously undescribed varieties of feather features (FF), in the form of lamellae emanating from curviplanar and curved fractures, as well as an "arrowhead"-like FF development with microlamellae originating from both sides of a PF, were observed. The timing of shatter cone formation was investigated by establishing temporal relations to the generation of various shock microscopic effects. Shatter cones are, thus, generated post- or syn-formation of PF, FF, subplanar fractures, and PDF. The earliest possible time for shatter cone formation is during the late stage of the compressional phase, that is, shock wave passage, of an impact event.

Gravity influences the visual representation of object tilt in parietal cortex.

PubMed

Rosenberg, Ari; Angelaki, Dora E

2014-10-22

Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an "earth-vertical" direction. Copyright © 2014 the authors 0270-6474/14/3414170-11$15.00/0.

Investigation of deformation effects on the decay properties of 12 C + α Cluster states in 16O

NASA Astrophysics Data System (ADS)

Soylu, A.; Koyuncu, F.; Coban, A.; Bayrak, O.; Freer, M.

2018-04-01

We have analyzed the elastic scattering angular distributions data of the α +12C reaction over a wide energy range (Elab = 28 . 2 to 35.5 MeV) within the framework of the Optical Model formalism. A double folding (DF) type real potential was used with a phenomenological Woods-Saxon-squared (WS2) type imaginary potential. Good agreement between the calculations and experimental data was obtained. By using the real DF potential we have calculated the properties of the α-cluster states in 16O by using the Gamow code as well as the α-decay widths by using the WKB method. We implemented a 12C + α cluster framework for the calculation of the excitation energies and decay widths of 16O as a function of the orientation of the planar 12C nucleus with respect to the α-particle. These calculations showed strong sensitivity of the widths and excitation energies to the orientation. Branching ratios were also calculated and though less sensitive to the 12C orientation, it was found that 12Cgs + α structure, with the α-particle orbiting the 12C in its ground state, is dominant. This work demonstrates that deformation, and the orientation, of 12C plays a crucial role in the understanding of the nature of the α-cluster states in 16O.

Couple Graph Based Label Propagation Method for Hyperspectral Remote Sensing Data Classification

NASA Astrophysics Data System (ADS)

Wang, X. P.; Hu, Y.; Chen, J.

2018-04-01

Graph based semi-supervised classification method are widely used for hyperspectral image classification. We present a couple graph based label propagation method, which contains both the adjacency graph and the similar graph. We propose to construct the similar graph by using the similar probability, which utilize the label similarity among examples probably. The adjacency graph was utilized by a common manifold learning method, which has effective improve the classification accuracy of hyperspectral data. The experiments indicate that the couple graph Laplacian which unite both the adjacency graph and the similar graph, produce superior classification results than other manifold Learning based graph Laplacian and Sparse representation based graph Laplacian in label propagation framework.

Multi-Centrality Graph Spectral Decompositions and Their Application to Cyber Intrusion Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Pin-Yu; Choudhury, Sutanay; Hero, Alfred

Many modern datasets can be represented as graphs and hence spectral decompositions such as graph principal component analysis (PCA) can be useful. Distinct from previous graph decomposition approaches based on subspace projection of a single topological feature, e.g., the centered graph adjacency matrix (graph Laplacian), we propose spectral decomposition approaches to graph PCA and graph dictionary learning that integrate multiple features, including graph walk statistics, centrality measures and graph distances to reference nodes. In this paper we propose a new PCA method for single graph analysis, called multi-centrality graph PCA (MC-GPCA), and a new dictionary learning method for ensembles ofmore » graphs, called multi-centrality graph dictionary learning (MC-GDL), both based on spectral decomposition of multi-centrality matrices. As an application to cyber intrusion detection, MC-GPCA can be an effective indicator of anomalous connectivity pattern and MC-GDL can provide discriminative basis for attack classification.« less

Graphs, matrices, and the GraphBLAS: Seven good reasons

DOE PAGES

Kepner, Jeremy; Bader, David; Buluç, Aydın; ...

2015-01-01

The analysis of graphs has become increasingly important to a wide range of applications. Graph analysis presents a number of unique challenges in the areas of (1) software complexity, (2) data complexity, (3) security, (4) mathematical complexity, (5) theoretical analysis, (6) serial performance, and (7) parallel performance. Implementing graph algorithms using matrix-based approaches provides a number of promising solutions to these challenges. The GraphBLAS standard (istcbigdata.org/GraphBlas) is being developed to bring the potential of matrix based graph algorithms to the broadest possible audience. The GraphBLAS mathematically defines a core set of matrix-based graph operations that can be used to implementmore » a wide class of graph algorithms in a wide range of programming environments. This paper provides an introduction to the GraphBLAS and describes how the GraphBLAS can be used to address many of the challenges associated with analysis of graphs.« less

Adjusting protein graphs based on graph entropy.

PubMed

Peng, Sheng-Lung; Tsay, Yu-Wei

2014-01-01

Measuring protein structural similarity attempts to establish a relationship of equivalence between polymer structures based on their conformations. In several recent studies, researchers have explored protein-graph remodeling, instead of looking a minimum superimposition for pairwise proteins. When graphs are used to represent structured objects, the problem of measuring object similarity become one of computing the similarity between graphs. Graph theory provides an alternative perspective as well as efficiency. Once a protein graph has been created, its structural stability must be verified. Therefore, a criterion is needed to determine if a protein graph can be used for structural comparison. In this paper, we propose a measurement for protein graph remodeling based on graph entropy. We extend the concept of graph entropy to determine whether a graph is suitable for representing a protein. The experimental results suggest that when applied, graph entropy helps a conformational on protein graph modeling. Furthermore, it indirectly contributes to protein structural comparison if a protein graph is solid.

Adjusting protein graphs based on graph entropy

PubMed Central

2014-01-01

Measuring protein structural similarity attempts to establish a relationship of equivalence between polymer structures based on their conformations. In several recent studies, researchers have explored protein-graph remodeling, instead of looking a minimum superimposition for pairwise proteins. When graphs are used to represent structured objects, the problem of measuring object similarity become one of computing the similarity between graphs. Graph theory provides an alternative perspective as well as efficiency. Once a protein graph has been created, its structural stability must be verified. Therefore, a criterion is needed to determine if a protein graph can be used for structural comparison. In this paper, we propose a measurement for protein graph remodeling based on graph entropy. We extend the concept of graph entropy to determine whether a graph is suitable for representing a protein. The experimental results suggest that when applied, graph entropy helps a conformational on protein graph modeling. Furthermore, it indirectly contributes to protein structural comparison if a protein graph is solid. PMID:25474347

OCAM - A CELSS modeling tool: Description and results. [Object-oriented Controlled Ecological Life Support System Analysis and Modeling

NASA Technical Reports Server (NTRS)

Drysdale, Alan; Thomas, Mark; Fresa, Mark; Wheeler, Ray

1992-01-01

Controlled Ecological Life Support System (CELSS) technology is critical to the Space Exploration Initiative. NASA's Kennedy Space Center has been performing CELSS research for several years, developing data related to CELSS design. We have developed OCAM (Object-oriented CELSS Analysis and Modeling), a CELSS modeling tool, and have used this tool to evaluate CELSS concepts, using this data. In using OCAM, a CELSS is broken down into components, and each component is modeled as a combination of containers, converters, and gates which store, process, and exchange carbon, hydrogen, and oxygen on a daily basis. Multiple crops and plant types can be simulated. Resource recovery options modeled include combustion, leaching, enzyme treatment, aerobic or anaerobic digestion, and mushroom and fish growth. Results include printouts and time-history graphs of total system mass, biomass, carbon dioxide, and oxygen quantities; energy consumption; and manpower requirements. The contributions of mass, energy, and manpower to system cost have been analyzed to compare configurations and determine appropriate research directions.

Semantic-gap-oriented active learning for multilabel image annotation.

PubMed

Tang, Jinhui; Zha, Zheng-Jun; Tao, Dacheng; Chua, Tat-Seng

2012-04-01

User interaction is an effective way to handle the semantic gap problem in image annotation. To minimize user effort in the interactions, many active learning methods were proposed. These methods treat the semantic concepts individually or correlatively. However, they still neglect the key motivation of user feedback: to tackle the semantic gap. The size of the semantic gap of each concept is an important factor that affects the performance of user feedback. User should pay more efforts to the concepts with large semantic gaps, and vice versa. In this paper, we propose a semantic-gap-oriented active learning method, which incorporates the semantic gap measure into the information-minimization-based sample selection strategy. The basic learning model used in the active learning framework is an extended multilabel version of the sparse-graph-based semisupervised learning method that incorporates the semantic correlation. Extensive experiments conducted on two benchmark image data sets demonstrated the importance of bringing the semantic gap measure into the active learning process.

Strain and vorticity analysis using small-scale faults and associated drag folds

NASA Astrophysics Data System (ADS)

Gomez-Rivas, Enrique; Bons, Paul D.; Griera, Albert; Carreras, Jordi; Druguet, Elena; Evans, Lynn

2007-12-01

Small-scale faults with associated drag folds in brittle-ductile rocks can retain detailed information on the kinematics and amount of deformation the host rock experienced. Measured fault orientation ( α), drag angle ( β) and the ratio of the thickness of deflected layers at the fault ( L) and further away ( T) can be compared with α, β and L/ T values that are calculated with a simple analytical model. Using graphs or a numerical best-fit routine, one can then determine the kinematic vorticity number and initial fault orientation that best fits the data. The proposed method was successfully tested on both analogue experiments and numerical simulations with BASIL. Using this method, a kinematic vorticity number of one (dextral simple shear) and a minimum finite strain of 2.5-3.8 was obtained for a population of antithetic faults with associated drag folds in a case study area at Mas Rabassers de Dalt on Cap de Creus in the Variscan of the easternmost Pyrenees, Spain.

Model-Based Fault Diagnosis: Performing Root Cause and Impact Analyses in Real Time

NASA Technical Reports Server (NTRS)

Figueroa, Jorge F.; Walker, Mark G.; Kapadia, Ravi; Morris, Jonathan

2012-01-01

Generic, object-oriented fault models, built according to causal-directed graph theory, have been integrated into an overall software architecture dedicated to monitoring and predicting the health of mission- critical systems. Processing over the generic fault models is triggered by event detection logic that is defined according to the specific functional requirements of the system and its components. Once triggered, the fault models provide an automated way for performing both upstream root cause analysis (RCA), and for predicting downstream effects or impact analysis. The methodology has been applied to integrated system health management (ISHM) implementations at NASA SSC's Rocket Engine Test Stands (RETS).

Genten: Software for Generalized Tensor Decompositions v. 1.0.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phipps, Eric T.; Kolda, Tamara G.; Dunlavy, Daniel

Tensors, or multidimensional arrays, are a powerful mathematical means of describing multiway data. This software provides computational means for decomposing or approximating a given tensor in terms of smaller tensors of lower dimension, focusing on decomposition of large, sparse tensors. These techniques have applications in many scientific areas, including signal processing, linear algebra, computer vision, numerical analysis, data mining, graph analysis, neuroscience and more. The software is designed to take advantage of parallelism present emerging computer architectures such has multi-core CPUs, many-core accelerators such as the Intel Xeon Phi, and computation-oriented GPUs to enable efficient processing of large tensors.

Transmural variation in elastin fiber orientation distribution in the arterial wall.

PubMed

Yu, Xunjie; Wang, Yunjie; Zhang, Yanhang

2018-01-01

The complex three-dimensional elastin network is a major load-bearing extracellular matrix (ECM) component of an artery. Despite the reported anisotropic behavior of arterial elastin network, it is usually treated as an isotropic material in constitutive models. Our recent multiphoton microscopy study reported a relatively uniform elastin fiber orientation distribution in porcine thoracic aorta when imaging from the intima side (Chow et al., 2014). However it is questionable whether the fiber orientation distribution obtained from a small depth is representative of the elastin network structure in the arterial wall, especially when developing structure-based constitutive models. To date, the structural basis for the anisotropic mechanical behavior of elastin is still not fully understood. In this study, we examined the transmural variation in elastin fiber orientation distribution in porcine thoracic aorta and its association with elastin anisotropy. Using multi-photon microscopy, we observed that the elastin fibers orientation changes from a relatively uniform distribution in regions close to the luminal surface to a more circumferential distribution in regions that dominate the media, then to a longitudinal distribution in regions close to the outer media. Planar biaxial tensile test was performed to characterize the anisotropic behavior of elastin network. A new structure-based constitutive model of elastin network was developed to incorporate the transmural variation in fiber orientation distribution. The new model well captures the anisotropic mechanical behavior of elastin network under both equi- and nonequi-biaxial loading and showed improvements in both fitting and predicting capabilities when compared to a model that only considers the fiber orientation distribution from the intima side. We submit that the transmural variation in fiber orientation distribution is important in characterizing the anisotropic mechanical behavior of elastin network and should be considered in constitutive modeling of an artery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vector Graph Assisted Pedestrian Dead Reckoning Using an Unconstrained Smartphone

PubMed Central

Qian, Jiuchao; Pei, Ling; Ma, Jiabin; Ying, Rendong; Liu, Peilin

2015-01-01

The paper presents a hybrid indoor positioning solution based on a pedestrian dead reckoning (PDR) approach using built-in sensors on a smartphone. To address the challenges of flexible and complex contexts of carrying a phone while walking, a robust step detection algorithm based on motion-awareness has been proposed. Given the fact that step length is influenced by different motion states, an adaptive step length estimation algorithm based on motion recognition is developed. Heading estimation is carried out by an attitude acquisition algorithm, which contains a two-phase filter to mitigate the distortion of magnetic anomalies. In order to estimate the heading for an unconstrained smartphone, principal component analysis (PCA) of acceleration is applied to determine the offset between the orientation of smartphone and the actual heading of a pedestrian. Moreover, a particle filter with vector graph assisted particle weighting is introduced to correct the deviation in step length and heading estimation. Extensive field tests, including four contexts of carrying a phone, have been conducted in an office building to verify the performance of the proposed algorithm. Test results show that the proposed algorithm can achieve sub-meter mean error in all contexts. PMID:25738763

Study of Double-Weighted Graph Model and Optimal Path Planning for Tourist Scenic Area Oriented Intelligent Tour Guide

NASA Astrophysics Data System (ADS)

Shi, Y.; Long, Y.; Wi, X. L.

2014-04-01

When tourists visiting multiple tourist scenic spots, the travel line is usually the most effective road network according to the actual tour process, and maybe the travel line is different from planned travel line. For in the field of navigation, a proposed travel line is normally generated automatically by path planning algorithm, considering the scenic spots' positions and road networks. But when a scenic spot have a certain area and have multiple entrances or exits, the traditional described mechanism of single point coordinates is difficult to reflect these own structural features. In order to solve this problem, this paper focuses on the influence on the process of path planning caused by scenic spots' own structural features such as multiple entrances or exits, and then proposes a doubleweighted Graph Model, for the weight of both vertexes and edges of proposed Model can be selected dynamically. And then discusses the model building method, and the optimal path planning algorithm based on Dijkstra algorithm and Prim algorithm. Experimental results show that the optimal planned travel line derived from the proposed model and algorithm is more reasonable, and the travelling order and distance would be further optimized.

P-Finder: Reconstruction of Signaling Networks from Protein-Protein Interactions and GO Annotations.

PubMed

Young-Rae Cho; Yanan Xin; Speegle, Greg

2015-01-01

Because most complex genetic diseases are caused by defects of cell signaling, illuminating a signaling cascade is essential for understanding their mechanisms. We present three novel computational algorithms to reconstruct signaling networks between a starting protein and an ending protein using genome-wide protein-protein interaction (PPI) networks and gene ontology (GO) annotation data. A signaling network is represented as a directed acyclic graph in a merged form of multiple linear pathways. An advanced semantic similarity metric is applied for weighting PPIs as the preprocessing of all three methods. The first algorithm repeatedly extends the list of nodes based on path frequency towards an ending protein. The second algorithm repeatedly appends edges based on the occurrence of network motifs which indicate the link patterns more frequently appearing in a PPI network than in a random graph. The last algorithm uses the information propagation technique which iteratively updates edge orientations based on the path strength and merges the selected directed edges. Our experimental results demonstrate that the proposed algorithms achieve higher accuracy than previous methods when they are tested on well-studied pathways of S. cerevisiae. Furthermore, we introduce an interactive web application tool, called P-Finder, to visualize reconstructed signaling networks.

F-Formation Detection: Individuating Free-Standing Conversational Groups in Images

PubMed Central

Setti, Francesco; Russell, Chris; Bassetti, Chiara; Cristani, Marco

2015-01-01

Detection of groups of interacting people is a very interesting and useful task in many modern technologies, with application fields spanning from video-surveillance to social robotics. In this paper we first furnish a rigorous definition of group considering the background of the social sciences: this allows us to specify many kinds of group, so far neglected in the Computer Vision literature. On top of this taxonomy we present a detailed state of the art on the group detection algorithms. Then, as a main contribution, we present a brand new method for the automatic detection of groups in still images, which is based on a graph-cuts framework for clustering individuals; in particular, we are able to codify in a computational sense the sociological definition of F-formation, that is very useful to encode a group having only proxemic information: position and orientation of people. We call the proposed method Graph-Cuts for F-formation (GCFF). We show how GCFF definitely outperforms all the state of the art methods in terms of different accuracy measures (some of them are brand new), demonstrating also a strong robustness to noise and versatility in recognizing groups of various cardinality. PMID:25996922

Sythesis of MCMC and Belief Propagation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Sungsoo; Chertkov, Michael; Shin, Jinwoo

Markov Chain Monte Carlo (MCMC) and Belief Propagation (BP) are the most popular algorithms for computational inference in Graphical Models (GM). In principle, MCMC is an exact probabilistic method which, however, often suffers from exponentially slow mixing. In contrast, BP is a deterministic method, which is typically fast, empirically very successful, however in general lacking control of accuracy over loopy graphs. In this paper, we introduce MCMC algorithms correcting the approximation error of BP, i.e., we provide a way to compensate for BP errors via a consecutive BP-aware MCMC. Our framework is based on the Loop Calculus (LC) approach whichmore » allows to express the BP error as a sum of weighted generalized loops. Although the full series is computationally intractable, it is known that a truncated series, summing up all 2-regular loops, is computable in polynomial-time for planar pair-wise binary GMs and it also provides a highly accurate approximation empirically. Motivated by this, we first propose a polynomial-time approximation MCMC scheme for the truncated series of general (non-planar) pair-wise binary models. Our main idea here is to use the Worm algorithm, known to provide fast mixing in other (related) problems, and then design an appropriate rejection scheme to sample 2-regular loops. Furthermore, we also design an efficient rejection-free MCMC scheme for approximating the full series. The main novelty underlying our design is in utilizing the concept of cycle basis, which provides an efficient decomposition of the generalized loops. In essence, the proposed MCMC schemes run on transformed GM built upon the non-trivial BP solution, and our experiments show that this synthesis of BP and MCMC outperforms both direct MCMC and bare BP schemes.« less

Molecular structure and conformations of para-methylbenzene sulfonamide and ortho-methylbenzene sulfonamide: gas electron diffraction and quantum chemical calculations study.

PubMed

Petrov, Vjacheslav M; Girichev, Georgiy V; Oberhammer, Heinz; Petrova, Valentina N; Giricheva, Nina I; Bardina, Anna V; Ivanov, Sergey N

2008-04-03

The molecular structure and conformational properties of para-methylbenzene sulfonamide (4-MBSA) and ortho-methylbenzene sulfonamide (2-MBSA) have been studied by gas electron diffraction (GED) and quantum chemical methods (B3LYP/6-311+G** and MP2/6-31G**). Quantum chemical calculations predict the existence of two conformers for 4-MBSA with the S-N bond perpendicular to the benzene plane and the NH2 group either eclipsing or staggering the S-O bonds of the SO2 group. Both conformers possess CS symmetry. The eclipsed form is predicted to be favored by DeltaE = 0.63 kcal/mol (B3LYP) or 1.00 kcal/mol (MP2). According to the calculations, the S-N bond in 2-MBSA can possess planar direction opposite the methyl group (phi(C2C1SN) = 180 degrees ) or nonplanar direction (phi(C2C1SN) approximately 60 degrees ). In both cases, the NH2 group can adopt eclipsed or staggered orientation, resulting in a total of four stable conformers. The nonplanar eclipsed conformer (C1 symmetry) and the planar eclipsed form (CS symmetry) are predicted to be favored. According to the GED analysis, the saturated vapor over solid 4-MBSA at T = 151(3) degrees C consists as mixture of the eclipsed (78(19) %) and staggered (22(19) %) forms. The saturated vapor over solid 2-MBSA at T = 157(3) degrees C consists as a mixture of the nonplanar eclipsed (69(11) %) and planar eclipsed (31(11) %) forms.

Characterizing Containment and Related Classes of Graphs,

DTIC Science & Technology

1985-01-01

Math . to appear. [G2] Golumbic,. Martin C., D. Rotem and J. Urrutia. "Comparability graphs and intersection graphs" Discrete Math . 43 (1983) 37-40. [G3...intersection classes of graphs" Discrete Math . to appear. [S2] Scheinerman, Edward R. Intersection Classes and Multiple Intersection Parameters of Graphs...graphs and of interval graphs" Canad. Jour. of blath. 16 (1964) 539-548. [G1] Golumbic, Martin C. "Containment graphs: and. intersection graphs" Discrete

A Collection of Features for Semantic Graphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eliassi-Rad, T; Fodor, I K; Gallagher, B

2007-05-02

Semantic graphs are commonly used to represent data from one or more data sources. Such graphs extend traditional graphs by imposing types on both nodes and links. This type information defines permissible links among specified nodes and can be represented as a graph commonly referred to as an ontology or schema graph. Figure 1 depicts an ontology graph for data from National Association of Securities Dealers. Each node type and link type may also have a list of attributes. To capture the increased complexity of semantic graphs, concepts derived for standard graphs have to be extended. This document explains brieflymore » features commonly used to characterize graphs, and their extensions to semantic graphs. This document is divided into two sections. Section 2 contains the feature descriptions for static graphs. Section 3 extends the features for semantic graphs that vary over time.« less

Graphing the order of the sexes: constructing, recalling, interpreting, and putting the self in gender difference graphs.

PubMed

Hegarty, Peter; Lemieux, Anthony F; McQueen, Grant

2010-03-01

Graphs seem to connote facts more than words or tables do. Consequently, they seem unlikely places to spot implicit sexism at work. Yet, in 6 studies (N = 741), women and men constructed (Study 1) and recalled (Study 2) gender difference graphs with men's data first, and graphed powerful groups (Study 3) and individuals (Study 4) ahead of weaker ones. Participants who interpreted graph order as evidence of author "bias" inferred that the author graphed his or her own gender group first (Study 5). Women's, but not men's, preferences to graph men first were mitigated when participants graphed a difference between themselves and an opposite-sex friend prior to graphing gender differences (Study 6). Graph production and comprehension are affected by beliefs and suppositions about the groups represented in graphs to a greater degree than cognitive models of graph comprehension or realist models of scientific thinking have yet acknowledged.

Extension of D-H parameter method to hybrid manipulators used in robot-assisted surgery.

PubMed

Singh, Amanpreet; Singla, Ashish; Soni, Sanjeev

2015-10-01

The main focus of this work is to extend the applicability of D-H parameter method to develop a kinematic model of a hybrid manipulator. A hybrid manipulator is a combination of open- and closed-loop chains and contains planar and spatial links. It has been found in the literature that D-H parameter method leads to ambiguities, when dealing with closed-loop chains. In this work, it has been observed that the D-H parameter method, when applied to a hybrid manipulator, results in an orientational inconsistency, because of which the method cannot be used to develop the kinematic model. In this article, the concept of dummy frames is proposed to resolve the orientational inconsistency and to develop the kinematic model of a hybrid manipulator. Moreover, the prototype of 7-degree-of-freedom hybrid manipulator, known as a surgeon-side manipulator to assist the surgeon during a medical surgery, is also developed to validate the kinematic model derived in this work. © IMechE 2015.

Craniofacial skeletal defects of adult zebrafish glypican 4 (knypek) mutants

PubMed Central

LeClair, Elizabeth E.; Mui, Stephanie R.; Huang, Angela; Topczewska, Jolanta M.; Topczewski, Jacek

2010-01-01

The heparan sulfate proteoglycan Glypican 4 (Gpc4) is part of the Wnt/planar cell polarity pathway, which is required for convergence and extension during zebrafish gastrulation. To observe Glypican 4-deficient phenotypes at later stages, we rescued gpc4−/− (knypek) homozygotes and raised them for more than one year. Adult mutants showed diverse cranial malformations of both dermal and endochondral bones, ranging from shortening of the rostral-most skull to loss of the symplectic. Additionally, the adult palatoquadrate cartilage was disorganized, with abnormal chondrocyte orientation. To understand how the palatoquadrate cartilage normally develops, we examined a juvenile series of wild type and mutant specimens. This identified two novel domains of elongated chondrocytes in the larval palatoquadrate, which normally form prior to endochondral ossification. In contrast, gpc4−/− larvae never form these domains, suggesting a failure of chondrocyte orientation, though not differentiation. Our findings implicate Gpc4 in the regulation of zebrafish cartilage and bone morphogenesis. PMID:19777561

Orientation-Controllable ZnO Nanorod Array Using Imprinting Method for Maximum Light Utilization in Dye-Sensitized Solar Cells.

PubMed

Jeong, Huisu; Song, Hui; Lee, Ryeri; Pak, Yusin; Kumaresan, Yogeenth; Lee, Heon; Jung, Gun Young

2015-12-01

We present a holey titanium dioxide (TiO2) film combined with a periodically aligned ZnO nanorod layer (ZNL) for maximum light utilization in dye-sensitized solar cells (DSCs). Both the holey TiO2 film and the ZNL were simultaneously fabricated by imprint technique with a mold having vertically aligned ZnO nanorod (NR) array, which was transferred to the TiO2 film after imprinting. The orientation of the transferred ZNL such as laid, tilted, and standing ZnO NRs was dependent on the pitch and height of the ZnO NRs of the mold. The photoanode composed of the holey TiO2 film with the ZNL synergistically utilized the sunlight due to enhanced light scattering and absorption. The best power conversion efficiency of 8.5 % was achieved from the DSC with the standing ZNL, which represented a 33 % improvement compared to the reference cell with a planar TiO2.

Shock attenuation at the Slate Islands revisited

NASA Technical Reports Server (NTRS)

Wu, S.; Robertson, P. B.; Grieve, R. A. F.

1993-01-01

This study of a more extensive suite of Slate Islands samples confirms previous interpretations. It indicates clearly that recorded shock pressures, as determined by planar deformation feature orientations, increased towards the center. The 'shock center' is very close (considering the structural movements during cavity modification) to that from an independent determination from shatter cone orientations. Shock metamorphism at a higher level in breccia clasts than in the adjacent country rocks is evidence that the shock event preceded the formation of the breccia dikes. These observations, which are consistent with those at other impact structures, are all contrary to the interpretation by Sage that breccia dike formation by diatreme action was the source of the shock event. There is no plausible reason to consider the Slate Islands as anything but the emergent portion of the central uplift of a complex impact crater. It cannot be cited as an example of endogenic shock in arguments regarding evidence of impact in the terrestrial stratigraphic record.

Transformation from Nanofibers to Nanoribbons in Poly(3-hexylthiophene) Solution by Adding Alkylthiols.

PubMed

Pan, Shuang; Zhu, Mingjing; He, Luze; Zhang, Hongdong; Qiu, Feng; Lin, Zhiqun; Peng, Juan

2018-05-10

An intriguing morphological transition from poly(3-hexylthiophene) (P3HT) 1D nanofibers to 2D nanoribbons enabled by the addition of a series of alkylthiols is reported. First, P3HT 1D nanofibers are formed due to strong anisotropic π-π stacking between planar rigid backbones. Upon the addition of alkylthiols, P3HT nanofibers are transformed into nanoribbons associated with the crystallographic transition from edge-on orientation to flat-on orientation. The content of alkylthiols has a great influence on the P3HT morphology in the solution. The mechanism of such a morphological transformation is discussed based on the interaction between alkylthiols and P3HT chains. This work offers an effective strategy to tailor the crystal morphology and dimension of P3HT, which not only improves the understanding of P3HT crystallization but also may enable such discovery into conjugated polymer-based optoelectronic devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evolution of finite-amplitude localized vortices in planar homogeneous shear flows

NASA Astrophysics Data System (ADS)

Karp, Michael; Shukhman, Ilia G.; Cohen, Jacob

2017-02-01

An analytical-based method is utilized to follow the evolution of localized initially Gaussian disturbances in flows with homogeneous shear, in which the base velocity components are at most linear functions of the coordinates, including hyperbolic, elliptic, and simple shear. Coherent structures, including counterrotating vortex pairs (CVPs) and hairpin vortices, are formed for the cases where the streamlines of the base flow are open (hyperbolic and simple shear). For hyperbolic base flows, the dominance of shear over rotation leads to elongation of the localized disturbance along the outlet asymptote and formation of CVPs. For simple shear CVPs are formed from linear and nonlinear disturbances, whereas hairpins are observed only for highly nonlinear disturbances. For elliptic base flows CVPs, hairpins and vortex loops form initially, however they do not last and break into various vortical structures that spread in the spanwise direction. The effect of the disturbance's initial amplitude and orientation is examined and the optimal orientation achieving maximal growth is identified.

Reintroducing electrostatics into macromolecular crystallographic refinement: application to neutron crystallography and DNA hydration.

PubMed

Fenn, Timothy D; Schnieders, Michael J; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S; Brunger, Axel T

2011-04-13

Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints, and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here, we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen-bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. Copyright © 2011 Elsevier Ltd. All rights reserved.

Reintroducing Electrostatics into Macromolecular Crystallographic Refinement: Application to Neutron Crystallography and DNA Hydration

PubMed Central

Fenn, Timothy D.; Schnieders, Michael J.; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S.; Brunger, Axel T.

2011-01-01

Summary Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. PMID:21481775

Inserting Thienyl Linkers into Conjugated Molecules for Efficient Multilevel Electronic Memory: A New Understanding of Charge-Trapping in Organic Materials.

PubMed

Li, Yang; Li, Hua; He, Jinghui; Xu, Qingfeng; Li, Najun; Chen, Dongyun; Lu, Jianmei

2016-03-18

The practical application of organic memory devices requires low power consumption and reliable device quality. Herein, we report that inserting thienyl units into D-π-A molecules can improve these parameters by tuning the texture of the film. Theoretical calculations revealed that introducing thienyl π bridges increased the planarity of the molecular backbone and extended the D-A conjugation. Thus, molecules with more thienyl spacers showed improved stacking and orientation in the film state relative to the substrates. The corresponding sandwiched memory devices showed enhanced ternary memory behavior, with lower threshold voltages and better repeatability. The conductive switching and variation in the performance of the memory devices were interpreted by using an extended-charge-trapping mechanism. Our study suggests that judicious molecular engineering can facilitate control of the orientation of the crystallite in the solid state to achieve superior multilevel memory performance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prickle1b mediates interpretation of migratory cues during zebrafish facial branchiomotor neuron migration

PubMed Central

Mapp, Oni M.; Wanner, Sarah J.; Rohrschneider, Monica R.; Prince, Victoria E.

2011-01-01

The facial branchiomotor neurons undergo a characteristic tangential migration in the vertebrate hindbrain. Several signaling mechanisms have been implicated in this process, including the non-canonical Wnt/planar cell polarity (PCP) pathway. However, the role of this signaling pathway in controlling the dynamics of these neurons is unclear. Here, we describe the cellular dynamics of the facial neurons as they migrate, focusing on the speed and direction of migration, extension of protrusions, cell shape and orientation. Furthermore, we show that the PET/LIM domain protein Prickle1b (Pk1b) is required for several aspects of these migratory behaviors, including cell orientation. However, we find that centrosome localization is not significantly affected by disruption of Pk1b function, suggesting that polarization of the neurons is not completely lost. Together, our data suggest that Pk1b function may be required to integrate the multiple migratory cues received by the neurons into polarization instructions for proper posterior movement. PMID:20503357

Solution processed nanogap organic diodes based on liquid crystalline materials

NASA Astrophysics Data System (ADS)

Wang, Yi-Fei; Iino, Hiroaki; Hanna, Jun-ichi

2017-09-01

Co-planar nanogap organic diodes were fabricated with smectic liquid crystalline materials of the benzothienobenzothiophene (BTBT) derivative by a spin-coating technique. A high rectification ratio of the order of 106 at ±3 V was achieved when a liquid crystalline material of 2,7-didecyl benzothieno[3,2-b][1]benzothiophene (10-BTBT-10) was used in a device configuration of Al/10-BTBT-10/pentafluorobenzenethiol-treated Au on a glass substrate, which was 4 orders higher than that of the device based on non-liquid crystalline materials of 2,7-dibutyl benzothieno[3,2-b][1]benzothiophene (4-BTBT-4) and BTBT. Similar results were also observed when another liquid crystalline material of ω, ω'-dioctylterthiophene (8-TTP-8) and a non-liquid crystalline material of terthiophene (TTP) were used. These improved rectifications can be ascribed to the self-assembly properties and controllable molecular orientation of liquid crystalline materials, which made uniform perpendicular oriented polycrystalline films favorable for superior charge transport in nano-channels.

LGN plays distinct roles in oral epithelial stratification, filiform papilla morphogenesis and hair follicle development

PubMed Central

Lough, Kendall J.; Patel, Jeet H.; Descovich, Carlos Patiño; Curtis, T. Anthony

2016-01-01

Oral epithelia protect against constant challenges by bacteria, viruses, toxins and injury while also contributing to the formation of ectodermal appendages such as teeth, salivary glands and lingual papillae. Despite increasing evidence that differentiation pathway genes are frequently mutated in oral cancers, comparatively little is known about the mechanisms that regulate normal oral epithelial development. Here, we characterize oral epithelial stratification and describe multiple distinct functions for the mitotic spindle orientation gene LGN (Gpsm2) in promoting differentiation and tissue patterning in the mouse oral cavity. Similar to its function in epidermis, apically localized LGN directs perpendicular divisions that promote stratification of the palatal, buccogingival and ventral tongue epithelia. Surprisingly, however, in dorsal tongue LGN is predominantly localized basally, circumferentially or bilaterally and promotes planar divisions. Loss of LGN disrupts the organization and morphogenesis of filiform papillae but appears to be dispensable for embryonic hair follicle development. Thus, LGN has crucial tissue-specific functions in patterning surface ectoderm and its appendages by controlling division orientation. PMID:27317810

First-principles calculations of orientation dependence of Si thermal oxidation based on Si emission model

NASA Astrophysics Data System (ADS)

Nagura, Takuya; Kawachi, Shingo; Chokawa, Kenta; Shirakawa, Hiroki; Araidai, Masaaki; Kageshima, Hiroyuki; Endoh, Tetsuo; Shiraishi, Kenji

2018-04-01

It is expected that the off-state leakage current of MOSFETs can be reduced by employing vertical body channel MOSFETs (V-MOSFETs). However, in fabricating these devices, the structure of the Si pillars sometimes cannot be maintained during oxidation, since Si atoms sometimes disappear from the Si/oxide interface (Si missing). Thus, in this study, we used first-principles calculations based on the density functional theory, and investigated the Si emission behavior at the various interfaces on the basis of the Si emission model including its atomistic structure and dependence on Si crystal orientation. The results show that the order in which Si atoms are more likely to be emitted during thermal oxidation is (111) > (110) > (310) > (100). Moreover, the emission of Si atoms is enhanced as the compressive strain increases. Therefore, the emission of Si atoms occurs more easily in V-MOSFETs than in planar MOSFETs. To reduce Si missing in V-MOSFETs, oxidation processes that induce less strain, such as wet or pyrogenic oxidation, are necessary.

Graphing with "LogoWriter."

ERIC Educational Resources Information Center

Yoder, Sharon K.

This book discusses four kinds of graphs that are taught in mathematics at the middle school level: pictographs, bar graphs, line graphs, and circle graphs. The chapters on each of these types of graphs contain information such as starting, scaling, drawing, labeling, and finishing the graphs using "LogoWriter." The final chapter of the…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fangyan; Zhang, Song; Chung Wong, Pak

Effectively visualizing large graphs and capturing the statistical properties are two challenging tasks. To aid in these two tasks, many sampling approaches for graph simplification have been proposed, falling into three categories: node sampling, edge sampling, and traversal-based sampling. It is still unknown which approach is the best. We evaluate commonly used graph sampling methods through a combined visual and statistical comparison of graphs sampled at various rates. We conduct our evaluation on three graph models: random graphs, small-world graphs, and scale-free graphs. Initial results indicate that the effectiveness of a sampling method is dependent on the graph model, themore » size of the graph, and the desired statistical property. This benchmark study can be used as a guideline in choosing the appropriate method for a particular graph sampling task, and the results presented can be incorporated into graph visualization and analysis tools.« less

Space configuration as an explanation for lithology-related cross-polarized radar image anomalies

NASA Technical Reports Server (NTRS)

Mccauley, J. R.

1972-01-01

Three rock types are described that produce dark cross-polarized images on Ka-band imagery: lava flows dating from Pleistocene and Holocene, some Tertiary volcanics, and certain massive sandstones. Their planar surfaces are large with respect to the wavelength of the Ka-band system, yet are small in comparison to the resolution. It is found that only outcrops with proper faceted surface orientations produce significant radar returns showing the dominance of specular reflectors. The omnidirectional attitude of the facets and their wide distribution on the outcrops explains the independence of look-direction that the flat-lying anomalous outcrops exhibit in production of darker cross-polarized images.

Hole filling with oriented sticks in ultrasound volume reconstruction

PubMed Central

Vaughan, Thomas; Lasso, Andras; Ungi, Tamas; Fichtinger, Gabor

2015-01-01

Abstract. Volumes reconstructed from tracked planar ultrasound images often contain regions where no information was recorded. Existing interpolation methods introduce image artifacts and tend to be slow in filling large missing regions. Our goal was to develop a computationally efficient method that fills missing regions while adequately preserving image features. We use directional sticks to interpolate between pairs of known opposing voxels in nearby images. We tested our method on 30 volumetric ultrasound scans acquired from human subjects, and compared its performance to that of other published hole-filling methods. Reconstruction accuracy, fidelity, and time were improved compared with other methods. PMID:26839907

Process for separating metallic from semiconducting single-walled carbon nanotubes

NASA Technical Reports Server (NTRS)

Sun, Ya-Ping (Inventor)

2008-01-01

A method for separating semiconducting single-walled carbon nanotubes from metallic single-walled carbon nanotubes is disclosed. The method utilizes separation agents that preferentially associate with semiconducting nanotubes due to the electrical nature of the nanotubes. The separation agents are those that have a planar orientation, .pi.-electrons available for association with the surface of the nanotubes, and also include a soluble portion of the molecule. Following preferential association of the separation agent with the semiconducting nanotubes, the agent/nanotubes complex is soluble and can be solubilized with the solution enriched in semiconducting nanotubes while the residual solid is enriched in metallic nanotubes.

Bias-induced conformational switching of supramolecular networks of trimesic acid at the solid-liquid interface

NASA Astrophysics Data System (ADS)

Ubink, J.; Enache, M.; Stöhr, M.

2018-05-01

Using the tip of a scanning tunneling microscope, an electric field-induced reversible phase transition between two planar porous structures ("chickenwire" and "flower") of trimesic acid was accomplished at the nonanoic acid/highly oriented pyrolytic graphite interface. The chickenwire structure was exclusively observed for negative sample bias, while for positive sample bias only the more densely packed flower structure was found. We suggest that the slightly negatively charged carboxyl groups of the trimesic acid molecule are the determining factor for this observation: their adsorption behavior varies with the sample bias and is thus responsible for the switching behavior.

Methyl 4-amino-3-methyl­benzoate

PubMed Central

Li, Xiang; Yuan, Lian-Shan; Wang, Dan; Liu, Shan; Yao, Cheng

2008-01-01

In the mol­ecule of the title compound, C9H11NO2, the methyl C and amino N atoms bonded to the benzene ring lie in the ring plane. Intra­molecular C—H⋯O hydrogen bonding results in the formation of a five-membered planar ring, which is oriented at a dihedral angle of 2.73 (3)° with respect to the benzene ring, so they are nearly coplanar. In the crystal structure, inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into chains elongated along the c axis and stacked along the b axis. PMID:21202370

Inter-layer potential for hexagonal boron nitride

NASA Astrophysics Data System (ADS)

Leven, Itai; Azuri, Ido; Kronik, Leeor; Hod, Oded

2014-03-01

A new interlayer force-field for layered hexagonal boron nitride (h-BN) based structures is presented. The force-field contains three terms representing the interlayer attraction due to dispersive interactions, repulsion due to anisotropic overlaps of electron clouds, and monopolar electrostatic interactions. With appropriate parameterization, the potential is able to simultaneously capture well the binding and lateral sliding energies of planar h-BN based dimer systems as well as the interlayer telescoping and rotation of double walled boron-nitride nanotubes of different crystallographic orientations. The new potential thus allows for the accurate and efficient modeling and simulation of large-scale h-BN based layered structures.

Optical position measurement for a Large Gap Magnetic Suspension System

NASA Technical Reports Server (NTRS)

Welch, Sharon S.; Shelton, Kevin J.; Clemmons, James I.

1991-01-01

This paper describes the design of an optical position measurement system which is being built as part of the NASA Langley Large Gap Magnetic Suspension System (LGMSS). The LGMSS is a five degree-of-freedom, large-gap magnetic suspension system which is being built for Langley Research Center as part of the Advanced Controls Test Facility (ACTF). The LGMSS consists of a planar array of electromagnets which levitate and position a cylindrically shaped model containing a permanent magnet core. The optical position measurement system provides information on the location and orientation of the model to the LGMSS control system to stabilize levitation of the model.

A preliminary assessment of the impact of 2-D exhaust-nozzle geometry on the cruise range of a hypersonic aircraft with top-mounted ramjet propulsion

NASA Technical Reports Server (NTRS)

Vahl, W. A.; Weidner, J. P.

1980-01-01

A theoretical study of full length and shortened, two dimensional, isentropic, exhaust nozzles integrated with top mounted ramjet propulsion nacelles were conducted. Both symmetric and asymmetric contoured nozzles with a range of angular orientations were considered. Performance comparisons to determine optimum installations for a representative hypersonic vehicle at Mach 5 cruise conditions are presented on the basis of cruise range, propulsive specific impulse, inlet area requirements, and overall lift drag ratio. The effect of approximating the nozzle internal contours with planar surfaces and the determination of viscous and frozen flow effects are also presented.

Benzil bis­(ketazine)

PubMed Central

Patra, Goutam Kumar; Mukherjee, Anindita; Ng, Seik Weng

2009-01-01

The title compound (systematic name: 1,1′,2,2′-tetra­phenyl-2,2′-azinodiethanone), C28H20N2O2, was obtained by the reaction of benzil monohydrazone with chromium(III) nitrate. The dibenzyl­idene hydrazine unit is nearly planar (r.m.s. deviation = 0.073 Å) and the two benzoyl units are oriented almost perpendicular to it [dihedral angle = 87.81 (2), 87.81 (2)°]. The mol­ecules are linked into chains along the c axis by C—H⋯O hydrogen bonds and the chains are cross-linked via C—H⋯π inter­actions involving the benzoyl phenyl rings. PMID:21583456

An algorithm for finding a similar subgraph of all Hamiltonian cycles

NASA Astrophysics Data System (ADS)

Wafdan, R.; Ihsan, M.; Suhaimi, D.

2018-01-01

This paper discusses an algorithm to find a similar subgraph called findSimSubG algorithm. A similar subgraph is a subgraph with a maximum number of edges, contains no isolated vertex and is contained in every Hamiltonian cycle of a Hamiltonian Graph. The algorithm runs only on Hamiltonian graphs with at least two Hamiltonian cycles. The algorithm works by examining whether the initial subgraph of the first Hamiltonian cycle is a subgraph of comparison graphs. If the initial subgraph is not in comparison graphs, the algorithm will remove edges and vertices of the initial subgraph that are not in comparison graphs. There are two main processes in the algorithm, changing Hamiltonian cycle into a cycle graph and removing edges and vertices of the initial subgraph that are not in comparison graphs. The findSimSubG algorithm can find the similar subgraph without using backtracking method. The similar subgraph cannot be found on certain graphs, such as an n-antiprism graph, complete bipartite graph, complete graph, 2n-crossed prism graph, n-crown graph, n-möbius ladder, prism graph, and wheel graph. The complexity of this algorithm is O(m|V|), where m is the number of Hamiltonian cycles and |V| is the number of vertices of a Hamiltonian graph.

Mathematical foundations of the GraphBLAS

DOE PAGES

Kepner, Jeremy; Aaltonen, Peter; Bader, David; ...

2016-12-01

The GraphBLAS standard (GraphBlas.org) is being developed to bring the potential of matrix-based graph algorithms to the broadest possible audience. Mathematically, the GraphBLAS defines a core set of matrix-based graph operations that can be used to implement a wide class of graph algorithms in a wide range of programming environments. This study provides an introduction to the mathematics of the GraphBLAS. Graphs represent connections between vertices with edges. Matrices can represent a wide range of graphs using adjacency matrices or incidence matrices. Adjacency matrices are often easier to analyze while incidence matrices are often better for representing data. Fortunately, themore » two are easily connected by matrix multiplication. A key feature of matrix mathematics is that a very small number of matrix operations can be used to manipulate a very wide range of graphs. This composability of a small number of operations is the foundation of the GraphBLAS. A standard such as the GraphBLAS can only be effective if it has low performance overhead. Finally, performance measurements of prototype GraphBLAS implementations indicate that the overhead is low.« less

Drawing dependent structures, mechanical properties and cyclization behaviors of polyacrylonitrile and polyacrylonitrile/carbon nanotube composite fibers prepared by plasticized spinning.

PubMed

Li, Xiang; Qin, Aiwen; Zhao, Xinzhen; Liu, Dapeng; Wang, Haiye; He, Chunju

2015-09-14

Drawing to change the structural properties and cyclization behaviors of the polyacrylonitrile (PAN) chains in crystalline and amorphous regions is carried out on PAN and PAN/carbon nanotube (CNT) composite fibers. Various characterization methods including Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and thermal gravimetric analysis are used to monitor the structural evolution and cyclization behaviors of the fibers. With an increase of the draw ratio during the plasticized spinning process, the structural parameters of the fibers, i.e. crystallinity and planar zigzag conformation, are decreased at first, and then increased, which are associated with the heat exchange rate and the oriented-crystallization rate. A possible mechanism for plasticized spinning is proposed to explain the changing trends of crystallinity and planar zigzag conformation. PAN and PAN/CNT fibers exhibit various cyclization behaviors induced by drawing, e.g., the initiation temperature for the cyclization (Ti) of PAN fibers is increased with increasing draw ratio, while Ti of PAN/CNT fibers is decreased. Drawing also facilitates cyclization and lowers the percentage of β-amino nitrile for PAN/CNT fibers during the stabilization.

Thin Layer Sensory Cues Affect Antarctic Krill Swimming Kinematics

NASA Astrophysics Data System (ADS)

True, A. C.; Webster, D. R.; Weissburg, M. J.; Yen, J.

2013-11-01

A Bickley jet (laminar, planar free jet) is employed in a recirculating flume system to replicate thin shear and phytoplankton layers for krill behavioral assays. Planar laser-induced fluorescence (LIF) and particle image velocimetry (PIV) measurements quantify the spatiotemporal structure of the chemical and free shear layers, respectively, ensuring a close match to in situ hydrodynamic and biochemical conditions. Path kinematics from digitized trajectories of free-swimming Euphausia superba examine the effects of hydrodynamic sensory cues (deformation rate) and bloom level phytoplankton patches (~1000 cells/mL, Tetraselamis spp.) on krill behavior (body orientation, swimming modes and kinematics, path fracticality). Krill morphology is finely tuned for receiving and deciphering both hydrodynamic and chemical information that is vital for basic life processes such as schooling behaviors, predator/prey, and mate interactions. Changes in individual krill behavior in response to ecologically-relevant sensory cues have the potential to produce population-scale phenomena with significant ecological implications. Krill are a vital trophic link between primary producers (phytoplankton) and larger animals (seabirds, whales, fish, penguins, seals) as well as the subjects of a valuable commercial fishery in the Southern Ocean; thus quantifying krill behavioral responses to relevant sensory cues is an important step towards accurately modeling Antarctic ecosystems.

Splitting a colon geometry with multiplanar clipping

NASA Astrophysics Data System (ADS)

Ahn, David K.; Vining, David J.; Ge, Yaorong; Stelts, David R.

1998-06-01

Virtual colonoscopy, a recent three-dimensional (3D) visualization technique, has provided radiologists with a unique diagnostic tool. Using this technique, a radiologist can examine the internal morphology of a patient's colon by navigating through a surface-rendered model that is constructed from helical computed tomography image data. Virtual colonoscopy can be used to detect early forms of colon cancer in a way that is less invasive and expensive compared to conventional endoscopy. However, the common approach of 'flying' through the colon lumen to visually search for polyps is tedious and time-consuming, especially when a radiologist loses his or her orientation within the colon. Furthermore, a radiologist's field of view is often limited by the 3D camera position located inside the colon lumen. We have developed a new technique, called multi-planar geometry clipping, that addresses these problems. Our algorithm divides a complex colon anatomy into several smaller segments, and then splits each of these segments in half for display on a static medium. Multi-planar geometry clipping eliminates virtual colonoscopy's dependence upon expensive, real-time graphics workstations by enabling radiologists to globally inspect the entire internal surface of the colon from a single viewpoint.

Measurement Model and Precision Analysis of Accelerometers for Maglev Vibration Isolation Platforms.

PubMed

Wu, Qianqian; Yue, Honghao; Liu, Rongqiang; Zhang, Xiaoyou; Ding, Liang; Liang, Tian; Deng, Zongquan

2015-08-14

High precision measurement of acceleration levels is required to allow active control for vibration isolation platforms. It is necessary to propose an accelerometer configuration measurement model that yields such a high measuring precision. In this paper, an accelerometer configuration to improve measurement accuracy is proposed. The corresponding calculation formulas of the angular acceleration were derived through theoretical analysis. A method is presented to minimize angular acceleration noise based on analysis of the root mean square noise of the angular acceleration. Moreover, the influence of installation position errors and accelerometer orientation errors on the calculation precision of the angular acceleration is studied. Comparisons of the output differences between the proposed configuration and the previous planar triangle configuration under the same installation errors are conducted by simulation. The simulation results show that installation errors have a relatively small impact on the calculation accuracy of the proposed configuration. To further verify the high calculation precision of the proposed configuration, experiments are carried out for both the proposed configuration and the planar triangle configuration. On the basis of the results of simulations and experiments, it can be concluded that the proposed configuration has higher angular acceleration calculation precision and can be applied to different platforms.