Higher order structure of aquaporin-4.
Nicchia, G P; Rossi, A; Mola, M G; Pisani, F; Stigliano, C; Basco, D; Mastrototaro, M; Svelto, M; Frigeri, A
2010-07-28
Unlike other mammalian AQPs, multiple tetramers of AQP4 associate in the plasma membrane to form peculiar structures called Orthogonal Arrays of Particles (OAPs), that are observable by freeze-fracture electron microscopy (FFEM). However, FFEM cannot give information about the composition of OAPs of different sizes, and due to its technical complexity is not easily applicable as a routine technique. Recently, we employed the 2D gel electrophoresis BN-SDS/PAGE that for the first time enabled the biochemical isolation of AQP4-OAPs from several tissues. We found that AQP4 protein is present in several higher-order complexes (membrane pools of supra-structures) which contain different ratios of M1/M23 isoforms corresponding to AQP4-OAPs of different size. In this paper, we illustrate in detail the potentiality of 2D BN/SDS-PAGE for analyzing AQP4 supra-structures, their relationship with the dystrophin glycoprotein complex and other membrane proteins, and their role as a specific target of Neuromyelitis Optica autoantibodies.
Chromatin Higher-order Structure and Dynamics
Woodcock, Christopher L.; Ghosh, Rajarshi P.
2010-01-01
The primary role of the nucleus as an information storage, retrieval, and replication site requires the physical organization and compaction of meters of DNA. Although it has been clear for many years that nucleosomes constitute the first level of chromatin compaction, this contributes a relatively small fraction of the condensation needed to fit the typical genome into an interphase nucleus or set of metaphase chromosomes, indicating that there are additional “higher order” levels of chromatin condensation. Identifying these levels, their interrelationships, and the principles that govern their occurrence has been a challenging and much discussed problem. In this article, we focus on recent experimental advances and the emerging evidence indicating that structural plasticity and chromatin dynamics play dominant roles in genome organization. We also discuss novel approaches likely to yield important insights in the near future, and suggest research areas that merit further study. PMID:20452954
Symplectic structures related with higher order variational problems
NASA Astrophysics Data System (ADS)
Kijowski, Jerzy; Moreno, Giovanni
2015-06-01
In this paper, we derive the symplectic framework for field theories defined by higher order Lagrangians. The construction is based on the symplectic reduction of suitable spaces of iterated jets. The possibility of reducing a higher order system of partial differential equations to a constrained first-order one, the symplectic structures naturally arising in the dynamics of a first-order Lagrangian theory, and the importance of the Poincaré-Cartan form for variational problems, are all well-established facts. However, their adequate combination corresponding to higher order theories is missing in the literature. Here we obtain a consistent and truly finite-dimensional canonical formalism, as well as a higher order version of the Poincaré-Cartan form. In our exposition, the rigorous global proofs of the main results are always accompanied by their local coordinate descriptions, indispensable to work out practical examples.
Tensor Spectral Clustering for Partitioning Higher-order Network Structures
Benson, Austin R.; Gleich, David F.; Leskovec, Jure
2016-01-01
Spectral graph theory-based methods represent an important class of tools for studying the structure of networks. Spectral methods are based on a first-order Markov chain derived from a random walk on the graph and thus they cannot take advantage of important higher-order network substructures such as triangles, cycles, and feed-forward loops. Here we propose a Tensor Spectral Clustering (TSC) algorithm that allows for modeling higher-order network structures in a graph partitioning framework. Our TSC algorithm allows the user to specify which higher-order network structures (cycles, feed-forward loops, etc.) should be preserved by the network clustering. Higher-order network structures of interest are represented using a tensor, which we then partition by developing a multilinear spectral method. Our framework can be applied to discovering layered flows in networks as well as graph anomaly detection, which we illustrate on synthetic networks. In directed networks, a higher-order structure of particular interest is the directed 3-cycle, which captures feedback loops in networks. We demonstrate that our TSC algorithm produces large partitions that cut fewer directed 3-cycles than standard spectral clustering algorithms. PMID:27812399
Tensor Spectral Clustering for Partitioning Higher-order Network Structures.
Benson, Austin R; Gleich, David F; Leskovec, Jure
2015-01-01
Spectral graph theory-based methods represent an important class of tools for studying the structure of networks. Spectral methods are based on a first-order Markov chain derived from a random walk on the graph and thus they cannot take advantage of important higher-order network substructures such as triangles, cycles, and feed-forward loops. Here we propose a Tensor Spectral Clustering (TSC) algorithm that allows for modeling higher-order network structures in a graph partitioning framework. Our TSC algorithm allows the user to specify which higher-order network structures (cycles, feed-forward loops, etc.) should be preserved by the network clustering. Higher-order network structures of interest are represented using a tensor, which we then partition by developing a multilinear spectral method. Our framework can be applied to discovering layered flows in networks as well as graph anomaly detection, which we illustrate on synthetic networks. In directed networks, a higher-order structure of particular interest is the directed 3-cycle, which captures feedback loops in networks. We demonstrate that our TSC algorithm produces large partitions that cut fewer directed 3-cycles than standard spectral clustering algorithms.
Higher-order structure of rRNA
NASA Technical Reports Server (NTRS)
Gutell, R. R.; Woese, C. R.
1986-01-01
A comparative search for phylogenetically covarying basepair replacements within potential helices has been the only reliable method to determine the correct secondary structure of the 3 rRNAs, 5S, 16S, and 23S. The analysis of 16S from a wide phylogenetic spectrum, that includes various branches of the eubacteria, archaebacteria, eucaryotes, in addition to the mitochondria and chloroplast, is beginning to reveal the constraints on the secondary structures of these rRNAs. Based on the success of this analysis, and the assumption that higher order structure will also be phylogenetically conserved, a comparative search was initiated for positions that show co-variation not involved in secondary structure helices. From a list of potential higher order interactions within 16S rRNA, two higher-order interactions are presented. The first of these interactions involves positions 570 and 866. Based on the extent of phylogenetic covariation between these positions while maintaining Watson-Crick pairing, this higher-order interaction is considered proven. The other interaction involves a minimum of six positions between the 1400 and 1500 regions of the 16S rRNA. Although these patterns of covariation are not as striking as the 570/866 interaction, the fact that they all exist in an anti-parallel fashion and that experimental methods previously implicated these two regions of the molecule in tRNA function suggests that these interactions be given serious consideration.
Stable static structures in models with higher-order derivatives
Bazeia, D.; Lobão, A.S.; Menezes, R.
2015-09-15
We investigate the presence of static solutions in generalized models described by a real scalar field in four-dimensional space–time. We study models in which the scalar field engenders higher-order derivatives and spontaneous symmetry breaking, inducing the presence of domain walls. Despite the presence of higher-order derivatives, the models keep to equations of motion second-order differential equations, so we focus on the presence of first-order equations that help us to obtain analytical solutions and investigate linear stability on general grounds. We then illustrate the general results with some specific examples, showing that the domain wall may become compact and that the zero mode may split. Moreover, if the model is further generalized to include k-field behavior, it may contribute to split the static structure itself.
Revealing Higher Order Protein Structure Using Mass Spectrometry
NASA Astrophysics Data System (ADS)
Chait, Brian T.; Cadene, Martine; Olinares, Paul Dominic; Rout, Michael P.; Shi, Yi
2016-06-01
The development of rapid, sensitive, and accurate mass spectrometric methods for measuring peptides, proteins, and even intact protein assemblies has made mass spectrometry (MS) an extraordinarily enabling tool for structural biology. Here, we provide a personal perspective of the increasingly useful role that mass spectrometric techniques are exerting during the elucidation of higher order protein structures. Areas covered in this brief perspective include MS as an enabling tool for the high resolution structural biologist, for compositional analysis of endogenous protein complexes, for stoichiometry determination, as well as for integrated approaches for the structural elucidation of protein complexes. We conclude with a vision for the future role of MS-based techniques in the development of a multi-scale molecular microscope.
Neutron scattering studies on chromatin higher-order structure
Graziano, V.; Gerchman, S.E.; Schneider, D.K.; Ramakrishnan, V.
1994-12-31
We have been engaged in studies of the structure and condensation of chromatin into the 30nm filament using small-angle neutron scattering. We have also used deuterated histone H1 to determine its location in the chromatin 30nm filament. Our studies indicate that chromatin condenses with increasing ionic strength to a limiting structure that has a mass per unit length of 6-7 nucleosomes/11 nm. They also show that the linker histone H1/H5 is located in the interior of the chromatin filament, in a position compatible with its binding to the inner face of the nucleosome. Analysis of the mass per unit length as a function of H5 stoichiometry suggests that 5-7 contiguous nucleosomes need to have H5 bound before a stable higher order structure can exist.
Chemical probes for higher-order structure in RNA.
Peattie, D A; Gilbert, W
1980-01-01
Three chemical reactions can probe the secondary and tertiary interactions of RNA molecules in solution. Dimethyl sulfate monitors the N-7 of guanosines and senses tertiary interactions there, diethyl pyrocarbonate detects stacking of adenosines, and an alternate dimethyl sulfate reaction examines the N-3 of cytidines and thus probes base pairing. The reactions work between 0 degrees C and 90 degrees C and at pH 4.5--8.5 in a variety of buffers. As an example we follow the progressive denaturation of yeast tRNAPhe terminally labeled with 32P as the tertiary and secondary structures sequentially melt out. A single autoradiograph of a terminally labeled molecule locates regions of higher-order structure and identifies the bases involved. Images PMID:6159633
A Higher Order Analysis of the Factor Structure of the Myers-Briggs Type Indicator.
ERIC Educational Resources Information Center
Johnson, William L.; Mauzey, Edward; Johnson, Annabel M.; Murphy, Stanley D.; Zimmerman, Kurt J.
2001-01-01
Examines the higher order structure of Form G of the Myers Briggs Type Indicator. A third order component analysis of a sample (N=926) found two higher order components. This higher order analysis contributes to the research literature pertaining to the generalized structure of the personality measure. (Contains 44 references and 1 table.) (GCP)
Higher order structures of the caseins: a paradox?
Technology Transfer Automated Retrieval System (TEKTRAN)
This book chapter deals with the molecular architecture of the major milk proteins, the caseins. Earlier theories of casein structure classified them as random coils; i.e., flexible without definite structural elements. Recent advances in the field of protein chemistry have significantly enhanced ...
The Structure of Higher Education: Order in the Academy
ERIC Educational Resources Information Center
Smith, Clair A.
2009-01-01
Higher education in the U.S. is provided by an interesting mix of public, private non-profit, and for-profit institutions. The for-profit educational firm serves the residual claimant owners and has the greatest incentive for efficient operation. The public and private non-profit schools have less efficient incentives, but benefit from charitable…
Higher order mode damping for a detuned structure
Kroll, N.; Thompson, K.; Bane, K.; Ko, K.; Miller, R.; Ruth, R.; Gluckstern, R.
1994-08-01
We report in this paper the current status of our investigation of the possibility of suppressing the wake reappearance by providing relatively weak damping via the vacuum manifolds. The four vacuum manifolds running the length of the structure also function as multimode waveguides which serve to drain power from the HOM`s through the large coupling slots located in each cell, except, as discussed later, for a few at each end of the manifolds.
Switchable photooxygenation catalysts that sense higher-order amyloid structures
NASA Astrophysics Data System (ADS)
Taniguchi, Atsuhiko; Shimizu, Yusuke; Oisaki, Kounosuke; Sohma, Youhei; Kanai, Motomu
2016-10-01
Proteins can misfold into amyloid structures that are associated with diseases; however, the same proteins often have important biological roles. To degrade selectively the amyloid form without affecting the fraction of functional protein is, therefore, an attractive goal. Here we report target-state-dependent photooxygenation catalysts that are active only when bound to the cross-β-sheet structure that is characteristic of pathogenic aggregated amyloid proteins. We show these catalysts can selectively oxygenate the amyloid form of amyloid β-protein (Aβ) 1-42 in the presence of non-amyloid off-target substrates. Furthermore, photooxygenation with a catalyst that bears an Aβ-binding peptide attenuated the Aβ pathogenicity in the presence of cells. We also show that selective photooxygenation is generally applicable to other amyloidogenic proteins (amylin, insulin, β2-microglobulin, transthyretin and α-synuclein) and does not affect the physiologically functional non-aggregate states of these proteins. This is the first report of an artificial catalyst that can be selectively and reversibly turned on and off depending on the structure and aggregation state of the substrate protein.
Development of higher-order modal methods for transient thermal and structural analysis
NASA Technical Reports Server (NTRS)
Camarda, Charles J.; Haftka, Raphael T.
1989-01-01
A force-derivative method which produces higher-order modal solutions to transient problems is evaluated. These higher-order solutions converge to an accurate response using fewer degrees-of-freedom (eigenmodes) than lower-order methods such as the mode-displacement or mode-acceleration methods. Results are presented for non-proportionally damped structural problems as well as thermal problems modeled by finite elements.
Higher order factor structure of the WISC-IV in a clinical neuropsychological sample.
Bodin, Doug; Pardini, Dustin A; Burns, Thomas G; Stevens, Abigail B
2009-09-01
A confirmatory factor analysis was conducted examining the higher order factor structure of the WISC-IV scores for 344 children who participated in neuropsychological evaluations at a large children's hospital. The WISC-IV factor structure mirrored that of the standardization sample. The second order general intelligence factor (g) accounted for the largest proportion of variance in the first-order latent factors and in the individual subtests, especially for the working memory index. The first-order processing speed factor exhibited the most unique variance beyond the influence of g. The results suggest that clinicians should not ignore the contribution of g when interpreting the first-order factors.
Huang, Richard Y-C; Chen, Guodong
2014-10-01
Characterization of therapeutic drugs is a crucial step in drug development in the biopharmaceutical industry. Analysis of protein therapeutics is a challenging task because of the complexities associated with large molecular size and 3D structures. Recent advances in hydrogen/deuterium-exchange mass spectrometry (HDX-MS) have provided a means to assess higher-order structure of protein therapeutics in solution. In this review, the principles and procedures of HDX-MS for protein therapeutics characterization are presented, focusing on specific applications of epitope mapping for protein-protein interactions and higher-order structure comparison studies for conformational dynamics of protein therapeutics.
Tullius, Ryan; Karimullah, Affar S; Rodier, Marion; Fitzpatrick, Brian; Gadegaard, Nikolaj; Barron, Laurence D; Rotello, Vincent M; Cooke, Graeme; Lapthorn, Adrian; Kadodwala, Malcolm
2015-07-08
Optical spectroscopic methods do not routinely provide information on higher order hierarchical structure (tertiary/quaternary) of biological macromolecules and assemblies. This necessitates the use of time-consuming and material intensive techniques, such as protein crystallography, NMR, and electron microscopy. Here we demonstrate a spectroscopic phenomenon, superchiral polarimetry, which can rapidly characterize ligand-induced changes in protein higher order (tertiary/quaternary) structure at the picogram level, which is undetectable using conventional CD spectroscopy. This is achieved by utilizing the enhanced sensitivity of superchiral evanescent fields to mesoscale chiral structure.
The Higher Order Factor Structure and Gender Invariance of the Pathological Narcissism Inventory
ERIC Educational Resources Information Center
Wright, Aidan G. C.; Lukowitsky, Mark R.; Pincus, Aaron L.; Conroy, David E.
2010-01-01
The Pathological Narcissism Inventory (PNI) is a recently developed multidimensional inventory for the assessment of pathological narcissism. The authors describe and report the results of two studies that investigate the higher order factor structure and gender invariance of the PNI. The results of the first study indicate that the PNI has a…
ERIC Educational Resources Information Center
Budsankom, Prayoonsri; Sawangboon, Tatsirin; Damrongpanit, Suntorapot; Chuensirimongkol, Jariya
2015-01-01
The purpose of the research is to develop and identify the validity of factors affecting higher order thinking skills (HOTS) of students. The thinking skills can be divided into three types: analytical, critical, and creative thinking. This analysis is done by applying the meta-analytic structural equation modeling (MASEM) based on a database of…
ERIC Educational Resources Information Center
McGill, Ryan J.; Canivez, Gary L.
2016-01-01
As recommended by Carroll, the present study examined the factor structure of the Wechsler Intelligence Scale for Children-Fourth Edition Spanish (WISC-IV Spanish) normative sample using higher order exploratory factor analytic techniques not included in the WISC-IV Spanish Technical Manual. Results indicated that the WISC-IV Spanish subtests were…
The higher order factor structure and gender invariance of the Pathological Narcissism Inventory.
Wright, Aidan G C; Lukowitsky, Mark R; Pincus, Aaron L; Conroy, David E
2010-12-01
The Pathological Narcissism Inventory (PNI) is a recently developed multidimensional inventory for the assessment of pathological narcissism. The authors describe and report the results of two studies that investigate the higher order factor structure and gender invariance of the PNI. The results of the first study indicate that the PNI has a higher order factor structure that conforms to the theoretical structure of pathological narcissism with one factor representing narcissistic grandiosity and the other capturing narcissistic vulnerability. These results uniquely place the PNI as the only measure to broadly assess the two phenotypic themes of pathological narcissism. In the second study, results from tests of measurement invariance indicate that the PNI performs similarly in large samples of men (n = 488) and women (n = 495). These results further establish the psychometric properties of the PNI and suggest that it is well suited for the assessment of pathological narcissism.
The post-mitotic state in neurons correlates with a stable nuclear higher-order structure
Aranda-Anzaldo, Armando
2012-01-01
Neurons become terminally differentiated (TD) post-mitotic cells very early during development yet they may remain alive and functional for decades. TD neurons preserve the molecular machinery necessary for DNA synthesis that may be reactivated by different stimuli but they never complete a successful mitosis. The non-reversible nature of the post-mitotic state in neurons suggests a non-genetic basis for it since no set of mutations has been able to revert it. Comparative studies of the nuclear higher-order structure in neurons and cells with proliferating potential suggest that the non-reversible nature of the post-mitotic state in neurons has a structural basis in the stability of the nuclear higher-order structure. PMID:22808316
Structure-Specific Ribonucleases for MS-Based Elucidation of Higher-Order RNA Structure
NASA Astrophysics Data System (ADS)
Scalabrin, Matteo; Siu, Yik; Asare-Okai, Papa Nii; Fabris, Daniele
2014-07-01
Supported by high-throughput sequencing technologies, structure-specific nucleases are experiencing a renaissance as biochemical probes for genome-wide mapping of nucleic acid structure. This report explores the benefits and pitfalls of the application of Mung bean (Mb) and V1 nuclease, which attack specifically single- and double-stranded regions of nucleic acids, as possible structural probes to be employed in combination with MS detection. Both enzymes were found capable of operating in ammonium-based solutions that are preferred for high-resolution analysis by direct infusion electrospray ionization (ESI). Sequence analysis by tandem mass spectrometry (MS/MS) was performed to confirm mapping assignments and to resolve possible ambiguities arising from the concomitant formation of isobaric products with identical base composition and different sequences. The observed products grouped together into ladder-type series that facilitated their assignment to unique regions of the substrate, but revealed also a certain level of uncertainty in identifying the boundaries between paired and unpaired regions. Various experimental factors that are known to stabilize nucleic acid structure, such as higher ionic strength, presence of Mg(II), etc., increased the accuracy of cleavage information, but did not completely eliminate deviations from expected results. These observations suggest extreme caution in interpreting the results afforded by these types of reagents. Regardless of the analytical platform of choice, the results highlighted the need to repeat probing experiments under the most diverse possible conditions to recognize potential artifacts and to increase the level of confidence in the observed structural information.
ANOVA-HDMR structure of the higher order nodal diffusion solution
Bokov, P. M.; Prinsloo, R. H.; Tomasevic, D. I.
2013-07-01
Nodal diffusion methods still represent a standard in global reactor calculations, but employ some ad-hoc approximations (such as the quadratic leakage approximation) which limit their accuracy in cases where reference quality solutions are sought. In this work we solve the nodal diffusion equations utilizing the so-called higher-order nodal methods to generate reference quality solutions and to decompose the obtained solutions via a technique known as High Dimensional Model Representation (HDMR). This representation and associated decomposition of the solution provides a new formulation of the transverse leakage term. The HDMR structure is investigated via the technique of Analysis of Variance (ANOVA), which indicates why the existing class of transversely-integrated nodal methods prove to be so successful. Furthermore, the analysis leads to a potential solution method for generating reference quality solutions at a much reduced calculational cost, by applying the ANOVA technique to the full higher order solution. (authors)
Simultaneous silence organizes structured higher-order interactions in neural populations
Shimazaki, Hideaki; Sadeghi, Kolia; Ishikawa, Tomoe; Ikegaya, Yuji; Toyoizumi, Taro
2015-01-01
Activity patterns of neural population are constrained by underlying biological mechanisms. These patterns are characterized not only by individual activity rates and pairwise correlations but also by statistical dependencies among groups of neurons larger than two, known as higher-order interactions (HOIs). While HOIs are ubiquitous in neural activity, primary characteristics of HOIs remain unknown. Here, we report that simultaneous silence (SS) of neurons concisely summarizes neural HOIs. Spontaneously active neurons in cultured hippocampal slices express SS that is more frequent than predicted by their individual activity rates and pairwise correlations. The SS explains structured HOIs seen in the data, namely, alternating signs at successive interaction orders. Inhibitory neurons are necessary to maintain significant SS. The structured HOIs predicted by SS were observed in a simple neural population model characterized by spiking nonlinearity and correlated input. These results suggest that SS is a ubiquitous feature of HOIs that constrain neural activity patterns and can influence information processing. PMID:25919985
Design and construction of higher-order structure and function in proteinosome-based protocells.
Huang, Xin; Patil, Avinash J; Li, Mei; Mann, Stephen
2014-06-25
The design and construction of higher-order structure and function in proteinosome microcompartments enclosed by a cross-linked membrane of amphiphilic bovine serum albumin/poly(N-isopropylacrylamide) (BSA-NH2/PNIPAAm) nanoconjugates is described. Three structure/function relationships are investigated: (i) differential chemical cross-linking for the control of membrane disassembly and regulated release of encapsulated genetic polymers; (ii) enzyme-mediated hydrogel structuring of the internal microenvironment to increase mechanical robustness and generate a molecularly crowded reaction environment; and (iii) self-production of a membrane-enclosing outer hydrogel wall for generating protease-resistant forms of the protein-polymer protocells. Our results highlight the potential of integrating aspects of supramolecular and polymer chemistry into the design and construction of novel bioinspired microcompartments as a step toward small-scale materials systems based on synthetic cellularity.
Barutcu, A. Rasim; Lajoie, Bryan R.; Fritz, Andrew J.; McCord, Rachel P.; Nickerson, Jeffrey A.; van Wijnen, Andre J.; Lian, Jane B.; Stein, Janet L.; Dekker, Job; Stein, Gary S.; Imbalzano, Anthony N.
2016-01-01
The packaging of DNA into chromatin plays an important role in transcriptional regulation and nuclear processes. Brahma-related gene-1 SMARCA4 (also known as BRG1), the essential ATPase subunit of the mammalian SWI/SNF chromatin remodeling complex, uses the energy from ATP hydrolysis to disrupt nucleosomes at target regions. Although the transcriptional role of SMARCA4 at gene promoters is well-studied, less is known about its role in higher-order genome organization. SMARCA4 knockdown in human mammary epithelial MCF-10A cells resulted in 176 up-regulated genes, including many related to lipid and calcium metabolism, and 1292 down-regulated genes, some of which encode extracellular matrix (ECM) components that can exert mechanical forces and affect nuclear structure. ChIP-seq analysis of SMARCA4 localization and SMARCA4-bound super-enhancers demonstrated extensive binding at intergenic regions. Furthermore, Hi-C analysis showed extensive SMARCA4-mediated alterations in higher-order genome organization at multiple resolutions. First, SMARCA4 knockdown resulted in clustering of intra- and inter-subtelomeric regions, demonstrating a novel role for SMARCA4 in telomere organization. SMARCA4 binding was enriched at topologically associating domain (TAD) boundaries, and SMARCA4 knockdown resulted in weakening of TAD boundary strength. Taken together, these findings provide a dynamic view of SMARCA4-dependent changes in higher-order chromatin organization and gene expression, identifying SMARCA4 as a novel component of chromatin organization. PMID:27435934
The role of the nucleosome acidic patch in modulating higher order chromatin structure.
Kalashnikova, Anna A; Porter-Goff, Mary E; Muthurajan, Uma M; Luger, Karolin; Hansen, Jeffrey C
2013-05-06
Higher order folding of chromatin fibre is mediated by interactions of the histone H4 N-terminal tail domains with neighbouring nucleosomes. Mechanistically, the H4 tails of one nucleosome bind to the acidic patch region on the surface of adjacent nucleosomes, causing fibre compaction. The functionality of the chromatin fibre can be modified by proteins that interact with the nucleosome. The co-structures of five different proteins with the nucleosome (LANA, IL-33, RCC1, Sir3 and HMGN2) recently have been examined by experimental and computational studies. Interestingly, each of these proteins displays steric, ionic and hydrogen bond complementarity with the acidic patch, and therefore will compete with each other for binding to the nucleosome. We first review the molecular details of each interface, focusing on the key non-covalent interactions that stabilize the protein-acidic patch interactions. We then propose a model in which binding of proteins to the nucleosome disrupts interaction of the H4 tail domains with the acidic patch, preventing the intrinsic chromatin folding pathway and leading to assembly of alternative higher order chromatin structures with unique biological functions.
An evaluation of higher-order model methods for calculating transient structural response
NASA Technical Reports Server (NTRS)
Camarda, Charles J.; Haftka, Raphael T.; Riley, Michael F.
1987-01-01
A higher-order modal method proposed by Leung for transient structural analysis entitled the force-derivative method is evaluated. This method repeatedly integrates by parts with respect to time the convolution-integral form of the structural response to produce successively better approximations to the contribution of the higher modes which are neglected in the modal summation. Comparisons are made of the force-derivative, the mode-displacement, and the mode-acceleration methods for several numerical example problems for various times, levels of damping, and forcing functions. The example problems include a tip-loaded cantilevered beam and a simply-supported multispan beam. The force-derivative method is shown to converge to an accurate solution in fewer modes than either the mode-displacement or the mode-acceleration methods. In addition, for problems in which there are a large number of closely-spaced frequencies whose mode shapes have a negligible contribution to the response, the force-derivative method is very effective in representing the effect of the important, but otherwise neglected, higher modes.
Higher Order Amyloid Fibril Structure by MAS NMR and DNP Spectroscopy
Debelouchina, Galia T.; Bayro, Marvin J.; Fitzpatrick, Anthony W.; Ladizhansky, Vladimir; Colvin, Michael T.; Caporini, Marc A.; Jaroniec, Christopher P.; Bajaj, Vikram S.; Rosay, Melanie; MacPhee, Cait E.; Vendruscolo, Michele; Maas, Werner E.; Dobson, Christopher M.; Griffin, Robert G.
2014-01-01
Protein magic angle spinning (MAS) NMR spectroscopy has generated structural models of several amyloid fibril systems, thus providing valuable information regarding the forces and interactions that confer the extraordinary stability of the amyloid architecture. Despite these advances, however, obtaining atomic resolution information describing the higher levels of structural organization within the fibrils remains a significant challenge. Here, we detail MAS NMR experiments and sample labeling schemes designed specifically to probe such higher order amyloid structure and we have applied them to the fibrils formed by an eleven-residue segment of the amyloidogenic protein transthyretin (TTR(105-115)). These experiments have allowed us to define unambiguously not only the arrangement of the peptide β-strands into β-sheets but also the β-sheet interfaces within each protofilament, and in addition to identify the nature of the protofilament-to-protofilament contacts that lead to the formation of the complete fibril. Our efforts have resulted in 111 quantitative distance and torsion angle restraints (10 per residue) that describe the various levels of structure organization. The experiments benefited extensively from the use of dynamic nuclear polarization (DNP), which in some cases allowed us to shorten the data acquisition time from days to hours and to improve significantly the signal-to-noise ratios of the spectra. The β-sheet interface and protofilament interactions identified here revealed local variations in the structure that result in multiple peaks for the exposed N- and C-termini of the peptide and in inhomogeneous line-broadening for the side-chains buried within the interior of the fibrils. PMID:24304221
Higher-order massive neutrino perturbations in large-scale structure
NASA Astrophysics Data System (ADS)
Führer, Florian; Wong, Yvonne Y. Y.
2015-03-01
We develop a higher-order perturbation theory for large-scale structure formation involving a free-streaming hot or warm dark matter species. We focus on the case of mixed cold dark matter and massive neutrinos, although our approach is applicable also to a single warm dark matter species. In order to capture the suppressed growth of neutrino density perturbations on small scales, we account for the full momentum dependence of the phase space distribution using the Vlasov equation, and derive from it a formal closed-form nonlinear equation for the neutrino density. Using a systematic perturbative expansion of this equation we compute high-order corrections to the neutrino density contrast without the explicit need to track the perturbed neutrino momentum distribution. We calculate the leading-order total matter bispectrum for several neutrino masses. Using our result as a benchmark, we test the accuracy of the fluid approximation and a linear approximation used in perturbative and N-body analyses, as well as a new hybrid approach that combines the exact linear evolution with the nonlinear structure of the fluid equations. Aiming at lesssim 1% accuracy, we find that the total matter bispectrum with a low neutrino mass m = 0.046 eV can be reproduced by all but the fluid approximation, while for larger neutrino masses m=0.46 → 0.93 eV only the hybrid approach has the desired accuracy on a large range of scales. This result serves as a cautionary note that approximate nonlinear models of neutrino clustering that reproduce the gross features of some observables may not suffice for precision calculations, nor are they guaranteed to apply to other observables. All of the approximation schemes fail to reproduce the bispectrum of the neutrino density perturbations at better than 20% accuracy across all scales, indicating that an exact treatment of nonlinear neutrino perturbations is necessary.
Self-association of collagen triple helic peptides into higher order structures.
Kar, Karunakar; Amin, Priyal; Bryan, Michael A; Persikov, Anton V; Mohs, Angela; Wang, Yuh-Hwa; Brodsky, Barbara
2006-11-03
Interest in self-association of peptides and proteins is motivated by an interest in the mechanism of physiologically higher order assembly of proteins such as collagen as well as the mechanism of pathological aggregation such as beta-amyloid formation. The triple helical form of (Pro-Hyp-Gly)(10), a peptide that has proved a useful model for molecular features of collagen, was found to self-associate, and its association properties are reported here. Turbidity experiments indicate that the triple helical peptide self-assembles at neutral pH via a nucleation-growth mechanism, with a critical concentration near 1 mM. The associated form is more stable than individual molecules by about 25 degrees C, and the association is reversible. The rate of self-association increases with temperature, supporting an entropically favored process. After self-association, (Pro-Hyp-Gly)(10) forms branched filamentous structures, in contrast with the highly ordered axially periodic structure of collagen fibrils. Yet a number of characteristics of triple helix assembly for the peptide resemble those of collagen fibril formation. These include promotion of fibril formation by neutral pH and increasing temperature; inhibition by sugars; and a requirement for hydroxyproline. It is suggested that these similar features for peptide and collagen self-association are based on common lateral underlying interactions between triple helical molecules mediated by hydrogen-bonded hydration networks involving hydroxyproline.
Higher-order chromatin structure in DSB induction, repair and misrepair.
Falk, Martin; Lukasova, Emilie; Kozubek, Stanislav
2010-01-01
Double-strand breaks (DSBs), continuously introduced into DNA by cell metabolism, ionizing radiation and some chemicals, are the biologically most deleterious type of genome damage, and must be accurately repaired to protect genomic integrity, ensure cell survival, and prevent carcinogenesis. Although a huge amount of information has been published on the molecular basis and biological significance of DSB repair, our understanding of DSB repair and its spatiotemporal arrangement is still incomplete. In particular, the role of higher-order chromatin structure in DSB induction and repair, movement of DSBs and the mechanism giving rise to chromatin exchanges, and many other currently disputed questions are discussed in this review. Finally, a model explaining the formation of chromosome translocations is proposed.
Statistical Mechanics of Nucleosomes Constrained by Higher-Order Chromatin Structure
NASA Astrophysics Data System (ADS)
Chereji, Răzvan V.; Morozov, Alexandre V.
2011-07-01
Eukaryotic DNA is packaged into chromatin: one-dimensional arrays of nucleosomes separated by stretches of linker DNA are folded into 30-nm chromatin fibers which in turn form higher-order structures (Felsenfeld and Groudine in Nature 421:448, 2003). Each nucleosome, the fundamental unit of chromatin, has 147 base pairs (bp) of DNA wrapped around a histone octamer (Richmond and Davey in Nature 423:145, 2003). In order to describe how chromatin fiber formation affects nucleosome positioning and energetics, we have developed a thermodynamic model of finite-size particles with effective nearest-neighbor interactions and arbitrary DNA-binding energies. We show that both one- and two-body interactions can be extracted from one-particle density profiles based on high-throughput maps of in vitro or in vivo nucleosome positions. Although a simpler approach that neglects two-body interactions (even if they are in fact present in the system) can be used to predict sequence determinants of nucleosome positions, the full theory is required to disentangle one- and two-body effects. Finally, we construct a minimal model in which nucleosomes are positioned primarily by steric exclusion and two-body interactions rather than intrinsic histone-DNA sequence preferences. The model reproduces nucleosome occupancy patterns observed over transcribed regions in living cells.
Thermo-Elastic Analysis of Internally Cooled Structures Using a Higher Order Theory
NASA Technical Reports Server (NTRS)
Arnold, Steven M.; Bednarcyk, Brett A.; Aboudi, Jacob
2001-01-01
This paper presents the results of a study on the thermomechanical behavior of internally cooled silicon nitride structures. Silicon nitride is under consideration for elevated temperature aerospace engine applications. and techniques for lowering the operating temperature of structures composed of this material are under development. Lowering the operating temperature provides a large payoff in terms of fatigue life and may be accomplished through the use of thermal barrier coatings (TBC's) and the novel concept of included cooling channels. Herein, an in-depth study is performed on the behavior of a flame-impinged silicon nitride plate with a TBC and internal channels cooled by forced air. The analysis is performed using the higher order theory for functionally graded materials (HOTFGM), which has been developed through NASA Glenn Research Center funding over the past several years. HOTFGM was chosen over the traditional finite element approach as a prelude to an examination of functionally graded silicon nitride structures for which HOTFGM is ideally suited. To accommodate the analysis requirement% of the internally cooled plate problem, two crucial enhancements were made to the two-dimensional Cartesian-based version of HOTFGM. namely, incorporation of internal boundary capabilities and incorporation of convective boundary conditions. Results indicate the viability and large benefits of cooling the plate via forced air through cooling channels. Furthermore, cooling can positively impact the stress and displacement fields present in the plate, yielding an additional payoff in terms of fatigue life. Finally, a spin-off capability resulted from inclusion of internal boundaries within HOTFGM; the ability to simulate the thermo-elastic response of structures with curved surfaces. This new capability is demonstrated, and through comparison with an analytical solution, shown to be viable and accurate.
RF-Thermal-Structural Analysis of a Waveguide Higher Order Mode Absorber
G. Cheng; E. F. Daly; R. A. Rimmer; M. Stirbet; L. Vogel; H. Wang; K. M. Wilson
2007-07-03
For an ongoing high current cryomodule project, a total of 5 higher order mode (HOM) absorbers are required per cavity. The load is designed to absorb Radio Frequency (RF) heat induced by HOMs in a 748.5MHz cavity. Each load is targeted at a 4 kW dissipation capability. Water cooling is employed to remove the heat generated in ceramic tiles and by surface losses on the waveguide walls. A sequentially coupled RF-thermal-structural analysis was developed in ANSYS to optimize the HOM load design. Frequency-dependent dielectric material properties measured from samples and RF power spectrum calculated by the beam-cavity interaction codes were considered. The coupled field analysis capability of ANSYS avoided mapping of results between separate RF and thermal/structural simulation codes. For verification purposes, RF results obtained from ANSYS were compared to those from MAFIA, HFSS, and Microwave Studio. Good agreement was reached and this confirms that multiple-field coupled analysis is a desirable choice in analysis of HOM loads. Similar analysis could be performed on other particle accelerator components where distributed RF heating and surface current induced losses are inevitable.
Higher-Order Theory: Structural/MicroAnalysis Code (HOTSMAC) Developed
NASA Technical Reports Server (NTRS)
Arnold, Steven M.
2002-01-01
The full utilization of advanced materials (be they composite or functionally graded materials) in lightweight aerospace components requires the availability of accurate analysis, design, and life-prediction tools that enable the assessment of component and material performance and reliability. Recently, a new commercially available software product called HOTSMAC (Higher-Order Theory--Structural/MicroAnalysis Code) was jointly developed by Collier Research Corporation, Engineered Materials Concepts LLC, and the NASA Glenn Research Center under funding provided by Glenn's Commercial Technology Office. The analytical framework for HOTSMAC is based on almost a decade of research into the coupled micromacrostructural analysis of heterogeneous materials. Consequently, HOTSMAC offers a comprehensive approach for analyzing/designing the response of components with various microstructural details, including certain advantages not always available in standard displacement-based finite element analysis techniques. The capabilities of HOTSMAC include combined thermal and mechanical analysis, time-independent and time-dependent material behavior, and internal boundary cells (e.g., those that can be used to represent internal cooling passages, see the preceding figure) to name a few. In HOTSMAC problems, materials can be randomly distributed and/or functionally graded (as shown in the figure, wherein the inclusions are distributed linearly), or broken down by strata, such as in the case of thermal barrier coatings or composite laminates.
Higher-order uncertainty relations
NASA Astrophysics Data System (ADS)
Wünsche, A.
2006-07-01
Using the non-negativity of Gram determinants of arbitrary order, we derive higher-order uncertainty relations for the symmetric uncertainty matrices of corresponding order n?>?2 to n Hermitean operators (n?=?2 is the usual case). The special cases of third-order and fourth-order uncertainty relations are considered in detail. The obtained third-order uncertainty relations are applied to the Lie groups SU(1,1) with three Hermitean basis operators (K1,K2,K0) and SU(2) with three Hermitean basis operators (J1,J2,J3) where, in particular, the group-coherent states of Perelomov type and of Barut Girardello type for SU(1,1) and the spin or atomic coherent states for SU(2) are investigated. The uncertainty relations for the determinant of the third-order uncertainty matrix are satisfied with the equality sign for coherent states and this determinant becomes vanishing for the Perelomov type of coherent states for SU(1,1) and SU(2). As an example of the application of fourth-order uncertainty relations, we consider the canonical operators (Q1,P1,Q2,P2) of two boson modes and the corresponding uncertainty matrix formed by the operators of the corresponding mean deviations, taking into account the correlations between the two modes. In two mathematical appendices, we prove the non-negativity of the determinant of correlation matrices of arbitrary order and clarify the principal structure of higher-order uncertainty relations.
NASA Astrophysics Data System (ADS)
Scholtes, Ingo; Wider, Nicolas; Garas, Antonios
2016-03-01
Despite recent advances in the study of temporal networks, the analysis of time-stamped network data is still a fundamental challenge. In particular, recent studies have shown that correlations in the ordering of links crucially alter causal topologies of temporal networks, thus invalidating analyses based on static, time-aggregated representations of time-stamped data. These findings not only highlight an important dimension of complexity in temporal networks, but also call for new network-analytic methods suitable to analyze complex systems with time-varying topologies. Addressing this open challenge, here we introduce a novel framework for the study of path-based centralities in temporal networks. Studying betweenness, closeness and reach centrality, we first show than an application of these measures to time-aggregated, static representations of temporal networks yields misleading results about the actual importance of nodes. To overcome this problem, we define path-based centralities in higher-order aggregate networks, a recently proposed generalization of the commonly used static representation of time-stamped data. Using data on six empirical temporal networks, we show that the resulting higher-order measures better capture the true, temporal centralities of nodes. Our results demonstrate that higher-order aggregate networks constitute a powerful abstraction, with broad perspectives for the design of new, computationally efficient data mining techniques for time-stamped relational data.
Decker, Scott L; Englund, Julia A; Roberts, Alycia M
2014-01-01
Factor-analytic studies support a hierarchical four-factor model for the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) with a prominent general, third-order factor. However, there is substantial disagreement on which type of higher-order model best fits the data and how different models should guide test interpretation in clinical practice, with many studies concluding interpretation should primarily be focused on general indicators of intelligence. We performed a series of confirmatory factor analyses with the WISC-IV standardization sample (N = 2,200, ages 6-16 years) to examine model fit and reexamined models used to support test interpretation at the general level. Consistent with previous research, bifactor models were difficult to identify; however, compared with bifactor and hierarchical models, the correlated factors model with no general higher-order factor provided the best fit to the data. Results from this study support the basic four-factor model specified in the WISC-IV technical manual, with test interpretation primarily focused at the factor level, rather than the general level suggested in previous studies.
Getting in (and out of) the loop: regulating higher order telomere structures
Luke-Glaser, Sarah; Poschke, Heiko; Luke, Brian
2012-01-01
The DNA at the ends of linear chromosomes (the telomere) folds back onto itself and forms an intramolecular lariat-like structure. Although the telomere loop has been implicated in the protection of chromosome ends from nuclease-mediated resection and unscheduled DNA repair activities, it potentially poses an obstacle to the DNA replication machinery during S-phase. Therefore, the coordinated regulation of telomere loop formation, maintenance, and resolution is required in order to establish a balance between protecting the chromosome ends and promoting their duplication prior to cell division. Until recently, the only factor known to influence telomere looping in human cells was TRF2, a component of the shelterin complex. Recent work in yeast and mouse cells has uncovered additional regulatory factors that affect the loop structure at telomeres. In the following “perspective” we outline what is known about telomere looping and highlight the latest results regarding the regulation of this chromosome end structure. We speculate about how the manipulation of the telomere loop may have therapeutic implications in terms of diseases associated with telomere dysfunction and uncontrolled proliferation. PMID:23226680
A generative spike train model with time-structured higher order correlations.
Trousdale, James; Hu, Yu; Shea-Brown, Eric; Josić, Krešimir
2013-01-01
Emerging technologies are revealing the spiking activity in ever larger neural ensembles. Frequently, this spiking is far from independent, with correlations in the spike times of different cells. Understanding how such correlations impact the dynamics and function of neural ensembles remains an important open problem. Here we describe a new, generative model for correlated spike trains that can exhibit many of the features observed in data. Extending prior work in mathematical finance, this generalized thinning and shift (GTaS) model creates marginally Poisson spike trains with diverse temporal correlation structures. We give several examples which highlight the model's flexibility and utility. For instance, we use it to examine how a neural network responds to highly structured patterns of inputs. We then show that the GTaS model is analytically tractable, and derive cumulant densities of all orders in terms of model parameters. The GTaS framework can therefore be an important tool in the experimental and theoretical exploration of neural dynamics.
A generative spike train model with time-structured higher order correlations
Trousdale, James; Hu, Yu; Shea-Brown, Eric; Josić, Krešimir
2013-01-01
Emerging technologies are revealing the spiking activity in ever larger neural ensembles. Frequently, this spiking is far from independent, with correlations in the spike times of different cells. Understanding how such correlations impact the dynamics and function of neural ensembles remains an important open problem. Here we describe a new, generative model for correlated spike trains that can exhibit many of the features observed in data. Extending prior work in mathematical finance, this generalized thinning and shift (GTaS) model creates marginally Poisson spike trains with diverse temporal correlation structures. We give several examples which highlight the model's flexibility and utility. For instance, we use it to examine how a neural network responds to highly structured patterns of inputs. We then show that the GTaS model is analytically tractable, and derive cumulant densities of all orders in terms of model parameters. The GTaS framework can therefore be an important tool in the experimental and theoretical exploration of neural dynamics. PMID:23908626
PcG-Mediated Higher-Order Chromatin Structures Modulate Replication Programs at the Drosophila BX-C
Comoglio, Federico; De Bardi, Marco; Paro, Renato; Orlando, Valerio
2013-01-01
Polycomb group proteins (PcG) exert conserved epigenetic functions that convey maintenance of repressed transcriptional states, via post-translational histone modifications and high order structure formation. During S-phase, in order to preserve cell identity, in addition to DNA information, PcG-chromatin-mediated epigenetic signatures need to be duplicated requiring a tight coordination between PcG proteins and replication programs. However, the interconnection between replication timing control and PcG functions remains unknown. Using Drosophila embryonic cell lines, we find that, while presence of specific PcG complexes and underlying transcription state are not the sole determinants of cellular replication timing, PcG-mediated higher-order structures appear to dictate the timing of replication and maintenance of the silenced state. Using published datasets we show that PRC1, PRC2, and PhoRC complexes differently correlate with replication timing of their targets. In the fully repressed BX-C, loss of function experiments revealed a synergistic role for PcG proteins in the maintenance of replication programs through the mediation of higher-order structures. Accordingly, replication timing analysis performed on two Drosophila cell lines differing for BX-C gene expression states, PcG distribution, and chromatin domain conformation revealed a cell-type-specific replication program that mirrors lineage-specific BX-C higher-order structures. Our work suggests that PcG complexes, by regulating higher-order chromatin structure at their target sites, contribute to the definition and the maintenance of genomic structural domains where genes showing the same epigenetic state replicate at the same time. PMID:23437006
ERIC Educational Resources Information Center
Bachelor, Patricia A.; Bachelor, Barry G.
1989-01-01
The existence of higher-order factors within the cognition and convergent production operations and product dimensions of the structure-of-intellect model of J. P. Guilford was investigated. Data from 240 aviation officer candidates and Naval air cadets were reanalyzed via maximum likelihood confirmatory factor analysis, using the LISREL program.…
ERIC Educational Resources Information Center
Canivez, Gary L.
2008-01-01
Orthogonal higher-order factor structure of the Stanford-Binet Intelligence Scales-Fifth Edition (SB-5; Roid, 2003a) for child and adolescent samples is reported. Multiple criteria for factor extraction unanimously supported extraction of only one dimension and a unidimensional model. However, following results from DiStefano and Dombrowski (2006)…
Orthogonal Higher Order Structure of the Wechsler Intelligence Scale for Children--Fourth Edition
ERIC Educational Resources Information Center
Watkins, Marley W.
2006-01-01
According to J. B. Carroll's (1993) 3-stratum theory, performance on any subtest reflects a mixture of both 2nd-order and 1st-order factors. To disentangle these influences, variance explained by the general factor should be extracted first. The 1st-order factors are then residualized, leaving them orthogonal to the general factor and each other.…
Pepenella, Sharon; Murphy, Kevin J; Hayes, Jeffrey J
2014-03-01
Eukaryotic chromatin is a hierarchical collection of nucleoprotein structures that package DNA to form chromosomes. The initial levels of packaging include folding of long strings of nucleosomes into secondary structures and array-array association into higher-order tertiary chromatin structures. The core histone tail domains are required for the assembly of higher-order structures and mediate short- and long-range intra- and inter-nucleosome interactions with both DNA and protein targets to direct their assembly. However, important details of these interactions remain unclear and are a subject of much interest and recent investigations. Here, we review work defining the interactions of the histone N-terminal tails with DNA and protein targets relevant to chromatin higher-order structures, with a specific emphasis on the contributions of H3 and H4 tails to oligonucleosome folding and stabilization. We evaluate both classic and recent experiments determining tail structures, effect of tail cleavage/loss, and posttranslational modifications of the tails on nucleosomes and nucleosome arrays, as well as inter-nucleosomal and inter-array interactions of the H3 and H4 N-terminal tails.
NASA Astrophysics Data System (ADS)
Lee, S. J.; Reddy, J. N.
2004-10-01
Third-order shear deformation theories of laminated composite shells are developed using the strain-displacement relations of Donnell and Sanders theories. These theories also account for geometric nonlinearity in the von Kármán sense. Analytical (Navier) solutions for vibration suppression in cross-ply laminated composite shells with surface mounted smart material layers are developed using the linear versions of the two shell theories and for simply supported boundary conditions. Numerical results are presented to bring out the parametric effects of shell types (cylindrical, spherical, and doubly curved shells) and material properties on vibration suppression. A simple negative velocity feedback control in a closed loop is used.
Higher-order proton structure corrections to the Lamb shift in muonic hydrogen
Carlson, Carl E.; Vanderhaeghen, Marc
2011-08-15
The recent conundrum with the proton charge radius inspires reconsideration of the corrections that enter into determinations of the proton size. We study the two-photon proton-structure corrections, with special consideration of the nonpole subtraction term in the dispersion relation and using fits to modern data to evaluate the energy contributions. We find that individual contributions change more than the total and present results with error estimates.
NASA Astrophysics Data System (ADS)
Lee, C. T.; Lee, C. C.
2015-04-01
This paper introduces a systematic approach to investigate a higher order nonlinear dispersive wave equation for modeling different wave modes. We present both the conventional KdV-type soliton and anomaly type solitons for the equation. We also show the conservation laws and Hamiltonian structures for the equation. Our results suggest that the underlying equation has more interacting soliton phenomena than one would have known for the classical KdV and Boussinesq equation.
Monte Carlo approach in assessing damage in higher order structures of DNA
NASA Technical Reports Server (NTRS)
Chatterjee, A.; Schmidt, J. B.; Holley, W. R.
1994-01-01
We have developed a computer monitor of nuclear DNA in the form of chromatin fibre. The fibres are modeled as a ideal solenoid consisting of twenty helical turns with six nucleosomes per turn. The chromatin model, in combination with are Monte Carlo theory of radiation damage induces by charged particles, based on general features of tack structure and stopping power theory, has been used to evaluate the influence of DNA structure on initial damage. An interesting has emerged from our calculations. Our calculated results predict the existence of strong spatial correlations in damage sites associated with the symmetries in the solenoidal model. We have calculated spectra of short fragments of double stranded DNA produced by multiple double strand breaks induced by both high and low LET radiation. The spectra exhibit peaks at multiples of approximately 85 base pairs (the nucleosome periodicity), and approximately 1000 base pairs (solenoid periodicity). Preliminary experiments to investigate the fragment distributions from irradiated DNA, made by B. Rydberg at Lawrence Berkeley Laboratory, confirm the existence of short DNA fragments and are in substantial agreement with the predictions of our theory.
Complex higher order derivative theories
Margalli, Carlos A.; Vergara, J. David
2012-08-24
In this work is considered a complex scalar field theory with higher order derivative terms and interactions. A procedure is developed to quantize consistently this system avoiding the presence of negative norm states. In order to achieve this goal the original real scalar high order field theory is extended to a complex space attaching a complex total derivative to the theory. Next, by imposing reality conditions the complex theory is mapped to a pair of interacting real scalar field theories without the presence of higher derivative terms.
Golay, Philippe; Lecerf, Thierry
2011-03-01
According to the most widely accepted Cattell-Horn-Carroll (CHC) model of intelligence measurement, each subtest score of the Wechsler Intelligence Scale for Adults (3rd ed.; WAIS-III) should reflect both 1st- and 2nd-order factors (i.e., 4 or 5 broad abilities and 1 general factor). To disentangle the contribution of each factor, we applied a Schmid-Leiman orthogonalization transformation (SLT) to the standardization data published in the French technical manual for the WAIS-III. Results showed that the general factor accounted for 63% of the common variance and that the specific contributions of the 1st-order factors were weak (4.7%-15.9%). We also addressed this issue by using confirmatory factor analysis. Results indicated that the bifactor model (with 1st-order group and general factors) better fit the data than did the traditional higher order structure. Models based on the CHC framework were also tested. Results indicated that a higher order CHC model showed a better fit than did the classical 4-factor model; however, the WAIS bifactor structure was the most adequate. We recommend that users do not discount the Full Scale IQ when interpreting the index scores of the WAIS-III because the general factor accounts for the bulk of the common variance in the French WAIS-III. The 4 index scores cannot be considered to reflect only broad ability because they include a strong contribution of the general factor.
Fang, Qianglin; Chen, Ping; Wang, Mingzhu; Fang, Junnan; Yang, Na; Li, Guohong; Xu, Rui-Ming
2016-01-26
Human cytomegalovirus (hCMV) immediate early 1 (IE1) protein associates with condensed chromatin of the host cell during mitosis. We have determined the structure of the chromatin-tethering domain (CTD) of IE1 bound to the nucleosome core particle, and discovered that IE1-CTD specifically interacts with the H2A-H2B acidic patch and impairs the compaction of higher-order chromatin structure. Our results suggest that IE1 loosens up the folding of host chromatin during hCMV infections.
Higher order turbulence closure models
NASA Technical Reports Server (NTRS)
Amano, Ryoichi S.; Chai, John C.; Chen, Jau-Der
1988-01-01
Theoretical models are developed and numerical studies conducted on various types of flows including both elliptic and parabolic. The purpose of this study is to find better higher order closure models for the computations of complex flows. This report summarizes three new achievements: (1) completion of the Reynolds-stress closure by developing a new pressure-strain correlation; (2) development of a parabolic code to compute jets and wakes; and, (3) application to a flow through a 180 deg turnaround duct by adopting a boundary fitted coordinate system. In the above mentioned models near-wall models are developed for pressure-strain correlation and third-moment, and incorporated into the transport equations. This addition improved the results considerably and is recommended for future computations. A new parabolic code to solve shear flows without coordinate tranformations is developed and incorporated in this study. This code uses the structure of the finite volume method to solve the governing equations implicitly. The code was validated with the experimental results available in the literature.
Yang, Rui; Kerschner, Jenny L.; Gosalia, Nehal; Neems, Daniel; Gorsic, Lidija K.; Safi, Alexias; Crawford, Gregory E.; Kosak, Steven T.; Leir, Shih-Hsing; Harris, Ann
2016-01-01
Higher order chromatin structure establishes domains that organize the genome and coordinate gene expression. However, the molecular mechanisms controlling transcription of individual loci within a topological domain (TAD) are not fully understood. The cystic fibrosis transmembrane conductance regulator (CFTR) gene provides a paradigm for investigating these mechanisms. CFTR occupies a TAD bordered by CTCF/cohesin binding sites within which are cell-type-selective cis-regulatory elements for the locus. We showed previously that intronic and extragenic enhancers, when occupied by specific transcription factors, are recruited to the CFTR promoter by a looping mechanism to drive gene expression. Here we use a combination of CRISPR/Cas9 editing of cis-regulatory elements and siRNA-mediated depletion of architectural proteins to determine the relative contribution of structural elements and enhancers to the higher order structure and expression of the CFTR locus. We found the boundaries of the CFTR TAD are conserved among diverse cell types and are dependent on CTCF and cohesin complex. Removal of an upstream CTCF-binding insulator alters the interaction profile, but has little effect on CFTR expression. Within the TAD, intronic enhancers recruit cell-type selective transcription factors and deletion of a pivotal enhancer element dramatically decreases CFTR expression, but has minor effect on its 3D structure. PMID:26673704
Higher-order organization of complex networks
Benson, Austin R.; Gleich, David F.; Leskovec, Jure
2016-01-01
Networks are a fundamental tool for understanding and modeling complex systems in physics, biology, neuroscience, engineering, and social science. Many networks are known to exhibit rich, lower-order connectivity patterns that can be captured at the level of individual nodes and edges. However, higher-order organization of complex networks—at the level of small network subgraphs—remains largely unknown. Here, we develop a generalized framework for clustering networks on the basis of higher-order connectivity patterns. This framework provides mathematical guarantees on the optimality of obtained clusters and scales to networks with billions of edges. The framework reveals higher-order organization in a number of networks, including information propagation units in neuronal networks and hub structure in transportation networks. Results show that networks exhibit rich higher-order organizational structures that are exposed by clustering based on higher-order connectivity patterns. PMID:27387949
Bergquist, Helen; Rocha, Cristina S. J.; Álvarez-Asencio, Rubén; Nguyen, Chi-Hung; Rutland, Mark. W.; Smith, C. I. Edvard; Good, Liam; Nielsen, Peter E.; Zain, Rula
2016-01-01
Expansion of (GAA)n repeats in the first intron of the Frataxin gene is associated with reduced mRNA and protein levels and the development of Friedreich’s ataxia. (GAA)n expansions form non-canonical structures, including intramolecular triplex (H-DNA), and R-loops and are associated with epigenetic modifications. With the aim of interfering with higher order H-DNA (like) DNA structures within pathological (GAA)n expansions, we examined sequence-specific interaction of peptide nucleic acid (PNA) with (GAA)n repeats of different lengths (short: n=9, medium: n=75 or long: n=115) by chemical probing of triple helical and single stranded regions. We found that a triplex structure (H-DNA) forms at GAA repeats of different lengths; however, single stranded regions were not detected within the medium size pathological repeat, suggesting the presence of a more complex structure. Furthermore, (GAA)4-PNA binding of the repeat abolished all detectable triplex DNA structures, whereas (CTT)5-PNA did not. We present evidence that (GAA)4-PNA can invade the DNA at the repeat region by binding the DNA CTT strand, thereby preventing non-canonical-DNA formation, and that triplex invasion complexes by (CTT)5-PNA form at the GAA repeats. Locked nucleic acid (LNA) oligonucleotides also inhibited triplex formation at GAA repeat expansions, and atomic force microscopy analysis showed significant relaxation of plasmid morphology in the presence of GAA-LNA. Thus, by inhibiting disease related higher order DNA structures in the Frataxin gene, such PNA and LNA oligomers may have potential for discovery of drugs aiming at recovering Frataxin expression. PMID:27846236
Higher-order mode absorption measurement of X-band choke-mode cavities in a radial line structure
NASA Astrophysics Data System (ADS)
Zha, Hao; Shi, Jiaru; Wu, Xiaowei; Chen, Huaibi
2016-04-01
An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.
Kida, Naoko; Katsuda, Yousuke; Yoshikawa, Yuko; Komeda, Seiji; Sato, Takaji; Saito, Yoshihiro; Chikuma, Masahiko; Suzuki, Mari; Imanaka, Tadayuki; Yoshikawa, Kenichi
2010-06-01
It is known that a 1,2,3-triazolato-bridged dinuclear platinum(II) complex, [{cis-Pt(NH(3))(2)}(2)(micro-OH)(micro-1,2,3-ta-N (1),N (2))](NO(3))(2) (AMTA), shows high in vitro cytotoxicity against several human tumor cell lines and circumvents cross-resistance to cisplatin. In the present study, we examined a dose- and time-dependent effect of AMTA on the higher-order structure of a large DNA, T4 phage DNA (166 kbp), by adapting single-molecule observation with fluorescence microscopy. It was found that AMTA induces the shrinking of DNA into a compact state with a much higher potency than cisplatin. From a quantitative analysis of the Brownian motion of individual DNA molecules in solution, it became clear that the density of a DNA segment in the compact state is about 2,000 times greater than that in the absence of AMTA. Circular dichroism spectra suggested that AMTA causes a transition from the B to the C form in the secondary structure of DNA, which is characterized by fast and slow processes. Electrophoretic measurements indicated that the binding of AMTA to supercoiled DNA induces unwinding of the double helix. Our results indicate that AMTA acts on DNA through both electrostatic interaction and coordination binding; the former causes a fast change in the secondary structure from the B to the C form, whereas the latter promotes shrinking in the higher-order structure as a relatively slow kinetic process. The shrinking effect of AMTA on DNA is attributable to the possible increase in the number of bridges along a DNA molecule. It is concluded that AMTA interacts with DNA in a manner markedly different from that of cisplatin.
NASA Astrophysics Data System (ADS)
Ali, Naseem; Aseyev, A.; McCraney, J.; Vuppuluri, V.; Abbass, O.; Al Jubaree, T.; Melius, M.; Cal, R. B.
2014-11-01
Hot-wire measurements obtained in a 3 × 3 wind turbine array boundary layer are utilized to analyze higher order statistics which include skewness, kurtosis as well as the ratios of structure functions and spectra. The ratios consist of wall-normal to streamwise components for both quantities. The aim is to understand the degree of anisotropy in the flow for the near- and far-wakes of the flow field where profiles at one diameter and five diameters are considered, respectively. The skewness at top tip for both wakes show a negative skewness while below the turbine canopy, this terms are positive. The kurtosis shows a Gaussian behavior in the near-wake immediately at hub-height. In addition, the effect due to the passage of the rotor in tandem with the shear layer at the top tip renders relatively high differences in the fourth order moment. The second order structure function and spectral ratios are found to exhibit anisotropic behavior at the top and bottom-tips for the large scales. Mixed structure functions and co-spectra are also considered in the context of isotropy.
NASA Technical Reports Server (NTRS)
Kerr, R. A.
1983-01-01
In a three dimensional simulation higher order derivative correlations, including skewness and flatness factors, are calculated for velocity and passive scalar fields and are compared with structures in the flow. The equations are forced to maintain steady state turbulence and collect statistics. It is found that the scalar derivative flatness increases much faster with Reynolds number than the velocity derivative flatness, and the velocity and mixed derivative skewness do not increase with Reynolds number. Separate exponents are found for the various fourth order velocity derivative correlations, with the vorticity flatness exponent the largest. Three dimensional graphics show strong alignment between the vorticity, rate of strain, and scalar-gradient fields. The vorticity is concentrated in tubes with the scalar gradient and the largest principal rate of strain aligned perpendicular to the tubes. Velocity spectra, in Kolmogorov variables, collapse to a single curve and a short minus 5/3 spectral regime is observed.
NASA Technical Reports Server (NTRS)
Pindera, Marek-Jerzy; Aboudi, Jacob
1998-01-01
The objective of this three-year project was to develop and deliver to NASA Lewis one-dimensional and two-dimensional higher-order theories, and related computer codes, for the analysis, optimization and design of cylindrical functionally graded materials/structural components for use in advanced aircraft engines (e.g., combustor linings, rotor disks, heat shields, blisk blades). To satisfy this objective, a quasi one-dimensional version of the higher-order theory, HOTCFGM-1D, and four computer codes based on this theory, for the analysis, design and optimization of cylindrical structural components functionally graded in the radial direction were developed. The theory is applicable to thin multi-phased composite shell/cylinders subjected to macroscopically axisymmetric thermomechanical and inertial loading applied uniformly along the axial direction such that the overall deformation is characterized by a constant average axial strain. The reinforcement phases are uniformly distributed in the axial and circumferential directions, and arbitrarily distributed in the radial direction, thereby allowing functional grading of the internal reinforcement in this direction.
Kar, Karunakar; Ibrar, Sajjad; Nanda, Vikas; Getz, Todd M; Kunapuli, Satya P; Brodsky, Barbara
2009-08-25
Aromatic residues are relatively rare within the collagen triple helix, but they appear to play a specialized role in higher-order structure and function. The role of aromatic amino acids in the self-assembly of triple-helical peptides was investigated in terms of the kinetics of self-association, the nature of aggregated species formed, and the ability of these species to activate platelet aggregation. The presence of aromatic residues on both ends of a type IV collagen model peptide is observed to greatly accelerate the kinetics of self-association, decreasing the lag time and leading to insoluble, well-defined linear fibrils as well as small soluble aggregates. Both macroscopic visible aggregates and small multimolecular complexes in solution are capable of inducing platelet aggregation through the glycoprotein VI receptor on platelets. Proline-aromatic CH...pi interactions are often observed within globular proteins and in protein complexes, and examination of molecular packing in the crystal structure of the integrin binding collagen peptide shows Phe interacts with Pro/Hyp in a neighboring triple-helical molecule. An intermolecular interaction between aromatic amino acids and imino acids within the triple helix is also supported by the observed inhibitory effect of isolated Phe amino acids on the self-association of (Pro-Hyp-Gly)(10). Given the high fraction of Pro and Hyp residues on the surface of collagen molecules, it is likely that imino acid-aromatic CH...pi interactions are important in formation of higher-order structure. We suggest that the catalysis of type I collagen fibrillogenesis by nonhelical telopeptides is due to specific intermolecular CH...pi interactions between aromatic residues in the telopeptides and Pro/Hyp residues within the triple helix.
Sujiwattanarat, Penporn; Thapana, Watcharaporn; Srikulnath, Kornsorn; Hirai, Yuriko; Hirai, Hirohisa; Koga, Akihiko
2015-05-14
Centromeres usually contain large amounts of tandem repeat DNA. Alpha satellite DNA (AS) is the most abundant tandem repeat DNA found in the centromeres of simian primates. The AS of humans contains sequences organized into higher-order repeat (HOR) structures, which are tandem arrays of larger repeat units consisting of multiple basic repeat units. HOR-carrying AS also occurs in other hominoids, but results reported to date for phylogenetically more remote taxa have been negative. Here we show direct evidence for clear HOR structures in AS of the owl monkey and common marmoset. These monkeys are New World monkey species that are located phylogenetically outside of hominoids. It is currently postulated that the presence of HOR structures in AS is unique to hominoids. Our results suggest that this view must be modified. A plausible explanation is that generation of HOR structures is a general event that occurs occasionally or frequently in primate centromeres, and that, in humans, HOR-carrying AS became predominant in the central region of the centromere. It is often difficult to assemble sequence reads of tandem repeat DNAs into accurate contig sequences; our careful sequencing strategy allowed us to overcome this problem.
Bain, David L; Brenowitz, Michael; Roberts, Christopher J
2016-12-01
Training researchers for positions in the United States biopharmaceutical industry has long been driven by academia. This commentary explores how the changing landscape of academic training will impact the industrial workforce, particularly with regard to the development of protein therapeutics in the area of biophysical and higher order structural characterization. We discuss how to balance future training and employment opportunities, how academic-industrial partnerships can help young scientists acquire the skills needed by their future employer, and how an appropriately trained workforce can facilitate the translation of new technology from academic to industrial laboratories. We also present suggestions to facilitate the coordinated development of industrial-academic educational partnerships to develop new training programs, and the ability of students to locate these programs, through the development of authoritative public resources.
Fabris, Daniele; Yu, Eizadora T.
2010-01-01
Chemical probing represents a very versatile alternative for studying the structure and dynamics of substrates that are intractable by established high-resolution techniques. The implementation of MS-based strategies for the characterization of probing products has not only extended the range of applicability to virtually all types of biopolymers, but has also paved the way for the introduction of new reagents that would not have been viable with traditional analytical platforms. As the availability of probing data is steadily increasing on the wings of the development of dedicated interpretation aids, powerful computational approaches have been explored to enable the effective utilization of such information to generate valid molecular models. This combination of factors has contributed to making the possibility of obtaining actual 3D structures by MS-based technologies (MS3D) a reality. Although approaches for achieving structure determination of unknown substrates or assessing the dynamics of known structures may share similar reagents and development trajectories, they clearly involve distinctive experimental strategies, analytical concerns, and interpretation paradigms. This Perspective offers a commentary on methods aimed at obtaining distance constraints for the modeling of full-fledged structures, while highlighting common elements, salient distinctions, and complementary capabilities exhibited by methods employed in dynamics studies. We discuss critical factors to be addressed for completing effective structural determinations and expose possible pitfalls of chemical methods. We survey programs developed for facilitating the interpretation of experimental data and discuss possible computational strategies for translating sparse spatial constraints into all-atom models. Examples are provided to illustrate how the concerted application of very diverse probing techniques can lead to the solution of actual biological substrates. PMID:20648672
McGill, Ryan J; Dombrowski, Stefan C
2016-11-19
The present study examined the factor structure of the Wide Range Assessment of Memory and Learning-Second Edition (WRAML2) core battery with participants from the normative sample aged 9 to 90 years (n = 880) using higher order exploratory and confirmatory factor analytic techniques that were not reported in the in the WRAML2 Administration and Technical Manual Exploratory factor analysis results suggested only one factor, whereas confirmatory factor analysis results favored the three factors posited by the test authors. Although model fit statistics were equivalent for the oblique, indirect hierarchical, and direct hierarchical measurement models, it was determined that the bifactor model best disclosed the influence of latent dimensions on WRAML2 manifest variables. In the three-factor bifactor model, the general factor accounted for 31% of the total variance and 69% of the common variance, whereas the three first-order factors combined accounted for 41% of the total variance and 31% of the common variance. Latent factor reliability coefficients (as estimated by ωh) indicated that only the general factor was measured with enough precision to warrant confident clinical interpretation. Implications for clinical interpretation of WRAML2 scores and the procedures utilized in the development of related measures are discussed.
Fasulo, Barbara; Deuring, Renate; Murawska, Magdalena; Gause, Maria; Dorighi, Kristel M.; Schaaf, Cheri A.; Dorsett, Dale; Brehm, Alexander; Tamkun, John W.
2012-01-01
dMi-2 is a highly conserved ATP-dependent chromatin-remodeling factor that regulates transcription and cell fates by altering the structure or positioning of nucleosomes. Here we report an unanticipated role for dMi-2 in the regulation of higher-order chromatin structure in Drosophila. Loss of dMi-2 function causes salivary gland polytene chromosomes to lose their characteristic banding pattern and appear more condensed than normal. Conversely, increased expression of dMi-2 triggers decondensation of polytene chromosomes accompanied by a significant increase in nuclear volume; this effect is relatively rapid and is dependent on the ATPase activity of dMi-2. Live analysis revealed that dMi-2 disrupts interactions between the aligned chromatids of salivary gland polytene chromosomes. dMi-2 and the cohesin complex are enriched at sites of active transcription; fluorescence-recovery after photobleaching (FRAP) assays showed that dMi-2 decreases stable association of cohesin with polytene chromosomes. These findings demonstrate that dMi-2 is an important regulator of both chromosome condensation and cohesin binding in interphase cells. PMID:22912596
Higher order modes in photonic crystal slabs.
Gansch, Roman; Kalchmair, Stefan; Detz, Hermann; Andrews, Aaron M; Klang, Pavel; Schrenk, Werner; Strasser, Gottfried
2011-08-15
We present a detailed investigation of higher order modes in photonic crystal slabs. In such structures the resonances exhibit a blue-shift compared to an ideal two-dimensional photonic crystal, which depends on the order of the slab mode and the polarization. By fabricating a series of photonic crystal slab photo detecting devices, with varying ratios of slab thickness to photonic crystal lattice constant, we are able to distinguish between 0th and 1st order slab modes as well as the polarization from the shift of resonances in the photocurrent spectra. This method complements the photonic band structure mapping technique for characterization of photonic crystal slabs.
Terada, Shoko; Hirai, Yuriko; Hirai, Hirohisa; Koga, Akihiko
2013-11-01
Alpha satellite DNA (AS), a major DNA component of primate centromeres, is composed of a tandem array of repeat units of approximately 170 bp. The AS of hominids (family Hominidae; humans and great apes) includes sequences organized into higher-order repeat (HOR) structures, with a periodic appearance of multiple copies of the basic repeat units. Here, we identified an HOR in AS of the siamang, a small ape phylogenetically distinct from hominids but included in hominoids (superfamily Hominoidea). We sequenced long stretches of genomic DNA, and found a repetition of blocks consisting of six and four basic repeat units. Thus, AS organization into HOR is an attribute of hominoids, rather than, as currently postulated, hominids. In addition to centromeres, siamangs carry AS in terminal heterochromatin blocks, and it cannot be determined at present whether these HOR-containing AS sequences originate from the centromere or from the terminal heterochromatin. Even if the latter is the case, these sequences might affect the composition of centromeric AS by being transferred to the centromere.
Kapiszewska, M.; Lange, C.S. )
1991-09-01
The authors have studied the effect of novobiocin treatment on radiation-induced damage and its repair in higher-order DNA structure in two mouse leukemia cell lines differing in their radiosensitivity, L5178Y-R (LY-R) and L5178Y-S (LY-S). They used the fluorescent halo technique to measure alterations in the superhelical density and the topological constraints of DNA in LY-R and LY-S nucleoids. The results for untreated cells show that both cell lines reached maximal DNA unwinding at the same concentration of propidium iodide (PI), whereas LY-S nucleoids were less efficient in their ability to rewind their DNA. The loop size did not differ significantly between the cell lines. Incubation of LY-R and LY-S cells with novobiocin at a concentration which does not influence survival (0.1 mM for 45 min), but inhibits DNA synthesis in LY-R cells (by 28%) to a greater extent than in LY-S cells (by 10%), also causes more DNA unwinding in LY-R nucleoids than in LY-S nucleoids. However, a decreased superhelical density was observed in nucleoids from both cell lines. Novobiocin applied before, and present during, irradiation prevents radiation-induced alterations in DNA supercoiling more efficiently in LY-R than in LY-S cells. The presence of novobiocin during the repair period increased DNA rewinding to levels not significantly different from control values in nucleoids from both cell lines.
Higher Order Languages for Robots,
1986-10-01
and procedures for math, I/O, character manipula- 4; tion, robot motion , and line tracking give pre-defined methods for real world control, which...and Shin (5) describe five levels of robot programming: task- " oriented, structured programming, primitive motion , point-to-point, and micro...spray painting robot the programmer (usually a shop floor operator) leads the robot through all of the motions for locating, moving, and orienting the
Baboi, Nicoleta
2002-09-19
Dipole modes are the main cause of transverse emittance dilution in the Japanese Linear Collider/Next Linear Collider (JLC/NLC). A diagnostic setup has been built in order to investigate them. The method is based on using a coaxial wire to excite and measure electromagnetic modes of accelerating structures. This method can offer a more efficient and less expensive procedure than the ASSET facility. Initial measurements have been made and are presented in this paper.
Paar, Vladimir; Pavin, Nenad; Basar, Ivan; Rosandić, Marija; Glunčić, Matko; Paar, Nils
2008-01-01
Background Identification of approximate tandem repeats is an important task of broad significance and still remains a challenging problem of computational genomics. Often there is no single best approach to periodicity detection and a combination of different methods may improve the prediction accuracy. Discrete Fourier transform (DFT) has been extensively used to study primary periodicities in DNA sequences. Here we investigate the application of DFT method to identify and study alphoid higher order repeats. Results We used method based on DFT with mapping of symbolic into numerical sequence to identify and study alphoid higher order repeats (HOR). For HORs the power spectrum shows equidistant frequency pattern, with characteristic two-level hierarchical organization as signature of HOR. Our case study was the 16 mer HOR tandem in AC017075.8 from human chromosome 7. Very long array of equidistant peaks at multiple frequencies (more than a thousand higher harmonics) is based on fundamental frequency of 16 mer HOR. Pronounced subset of equidistant peaks is based on multiples of the fundamental HOR frequency (multiplication factor n for nmer) and higher harmonics. In general, nmer HOR-pattern contains equidistant secondary periodicity peaks, having a pronounced subset of equidistant primary periodicity peaks. This hierarchical pattern as signature for HOR detection is robust with respect to monomer insertions and deletions, random sequence insertions etc. For a monomeric alphoid sequence only primary periodicity peaks are present. The 1/fβ – noise and periodicity three pattern are missing from power spectra in alphoid regions, in accordance with expectations. Conclusion DFT provides a robust detection method for higher order periodicity. Easily recognizable HOR power spectrum is characterized by hierarchical two-level equidistant pattern: higher harmonics of the fundamental HOR-frequency (secondary periodicity) and a subset of pronounced peaks corresponding to
Gee, Anthony; Shin, Young-Min
2013-07-15
A multi-beam traveling wave amplifier designed with an overmoded staggered double grating array was examined by small signal analysis combined with simulation. Eigenmode and S-parameter analyses show that the 2 cm long slow wave structure (SWS) has 1–5 dB insertion loss over the passband (TM{sub 31} mode) with ∼28% cold bandwidth. Analytic gain calculation indicates that in the SWS, TM{sub 31}-mode is amplified with 15–20 dB/beam at 64–84 GHz with three elliptical beams of 10 kV and 150 mA/beam, which was compared with particle-in-cell (PIC) simulations. PIC analysis on the analysis of instability with zero-input driving excitations demonstrated that background noises and non-operating lower order modes are noticeably suppressed by implanting equidistant dielectric absorbers; the overmoded structure only allowed the desired 3rd order mode to propagate in the structure. The designed circuit structure can be widely applied to multi-beam devices for high power RF generation.
Gee, Anthony; Shin, Young-Min
2013-01-01
A multi-beam traveling wave amplifier designed with an overmoded staggered double grating array was examined by small signal analysis combined with simulation. Eigenmode and S-parameter analyses show that the 2cm long slow wave structure (SWS) has 1-5dB insertion loss over the passband (TM31 mode) with ~28% cold bandwidth. Analytic gain calculation indicates that in the SWS, TM31-mode is amplified with 15–20 dB/beam at 64–84GHz with three elliptical beams of 10kV and 150mA/beam, which was compared with particle-in-cell (PIC) simulations. PIC analysis on the analysis of instability with zero-input driving excitations demonstrated that background noises and non-operating lower order modes are noticeably suppressed by implanting equidistant dielectric absorbers; the overmoded structure only allowed the desired 3rd order mode to propagate in the structure. The designed circuit structure can be widely applied to multi-beam devices for high power RF generation.
Allen, P N; Noller, H F
1989-08-05
We have studied the effects of protein mutations on the higher order structure of 16 S rRNA in Escherichia coli ribosomes, using a set of structure-sensitive chemical probes. Ten mutant strains were studied, which contained alterations in ribosomal proteins S4 and S12, including double mutants containing both altered S4 and S12. Two ribosomal ambiguity (ram) S4 mutant strains, four streptomycin resistant (SmR) S12 mutant strains, one streptomycin pseudodependent (SmP) S12 mutant strain, one streptomycin dependent (SmD) S12 mutant strain and two streptomycin independent (Sm1) double mutants (containing both-SmD and ram mutations) were probed and compared to an isogenic wild-type strain. In ribosomes from strains containing S4 ram mutations, nucleotides A8 and A26 become more reactive to dimethyl sulfate (DMS) at their N-1 positions. In ribosomes from strains bearing the SmD allele, A908, A909, A1413 and G1487 are significantly less reactive to chemical probes. These same effects are observed when the S4 and S12 mutations are present simultaneously in the double mutants. An interesting correlation is found between the reactivity of A908 and the miscoding potential of SmR, SmD, SmP and wild-type ribosomes; the reactivity of A908 increases as the translational error frequency of the ribosomes increases. In the case of ram ribosomes, the reactivity of A908 resembles that of wild-type, unless tRNA is bound, in which case it becomes hyper-reactive. Similarly, streptomycin has little effect on A908 in wild-type ribosomes unless tRNA is bound, in which case its reactivity increases to resemble that of ram ribosomes with bound tRNA. Finally, interaction of streptomycin with SmP and SmD ribosomes causes the reactivity of A908 to increase to near-wild-type levels. A simple model is proposed, in which the reactivity of A908 reflects the position of an equilibrium between two conformational states of the 30 S subunit, one of which is DMS-reactive, and the other DMS
Analogy, higher order thinking, and education.
Richland, Lindsey Engle; Simms, Nina
2015-01-01
Analogical reasoning, the ability to understand phenomena as systems of structured relationships that can be aligned, compared, and mapped together, plays a fundamental role in the technology rich, increasingly globalized educational climate of the 21st century. Flexible, conceptual thinking is prioritized in this view of education, and schools are emphasizing 'higher order thinking', rather than memorization of a cannon of key topics. The lack of a cognitively grounded definition for higher order thinking, however, has led to a field of research and practice with little coherence across domains or connection to the large body of cognitive science research on thinking. We review literature on analogy and disciplinary higher order thinking to propose that relational reasoning can be productively considered the cognitive underpinning of higher order thinking. We highlight the utility of this framework for developing insights into practice through a review of mathematics, science, and history educational contexts. In these disciplines, analogy is essential to developing expert-like disciplinary knowledge in which concepts are understood to be systems of relationships that can be connected and flexibly manipulated. At the same time, analogies in education require explicit support to ensure that learners notice the relevance of relational thinking, have adequate processing resources available to mentally hold and manipulate relations, and are able to recognize both the similarities and differences when drawing analogies between systems of relationships.
NASA Astrophysics Data System (ADS)
Yomba, Emmanuel; Peng, Yan-Ze
2006-01-01
By means of the Weiss Tabor Carnevale (WTC) truncation method and the general variable separation approach (GVSA), analytical investigation of the integrable (2+1)-dimensional higher-order Broer Kaup (HBK) system shows, due to the possibility of selecting three arbitrary func.tions, the existence of interacting coherent excitations such as dromions, solitons, periodic solitons, etc. The interaction between some of the localized solutions are elastic because they pass through each other and preserve their shapes and velocities, the only change being the phase shift. However, as for some soliton models, completely non-elastic interactions have been found in this model. These non-elastic interactions are characterized by the fact that, at a specific time, one soliton may fission to two or more solitons; or on the contrary, two or more solitons will fuse to one soliton.
Higher-Order Superposition for Dependent Types,
2007-11-02
Proofs for Higher-Order Rewrite Systems, J. Heering, K. Meinke , B. Moller, T. Nipkow ed., Higher Order Algebra, Logic and Term Rewriting, Lect. Notes in...Heering, K. Meinke , B. Moller, T. Nipkow ed., Higher Order Algebra, Logic and Term Rewriting, Lect. Notes in Comp. Sci., Vol 816, Springer Verlag, 1994, pp. 305-325
Systems with Higher-order Modulation
NASA Astrophysics Data System (ADS)
Achiam, Yaakov; Kaplan, Arkady; Seimetz, Matthias
The chapter covers concepts, systems aspects, and key components for higher-order modulation. The introductory section presents relevant variants of higher-order modulation formats and includes coherent detection and coherent optical orthogonal frequency-division multiplexing as well. The next section is devoted to system configurations with particular emphasis on transmitter structures and receiver concepts, whereas the subsequent chapter focuses on key components. Included are LiNbO3-based quadrature modulators, integrated coherent receivers, in particular 90° hybrids, ranging from new concepts to proven implementations. A treatment of integrated balanced four-branch receivers ranges from theoretical analysis to the presentation of commercially available devices. The chapter concludes with a discussion of system trends and expected future developments.
Arthur, Kelly K; Dinh, Nikita; Gabrielson, John P
2015-04-01
Differential scanning calorimetry (DSC) is a useful tool for monitoring thermal stability of the molecular conformation of proteins. Here, we present an example of the sensitivity of DSC to changes in stability arising from a common chemical degradation pathway, oxidation. This Note is part of a series of industry case studies demonstrating the application of higher order structure data for technical decision making. For this study, six protein products from three structural classes were evaluated at multiple levels of oxidation. For each protein, the melting temperature (Tm ) decreased linearly as a function of oxidation; however, differences in the rate of change in Tm , as well as differences in domain Tm stability were observed across and within structural classes. For one protein, analysis of the impact of oxidation on protein function was also performed. For this protein, DSC was shown to be a leading indicator of decreased antigen binding suggesting a subtle conformation change may be underway that can be detected using DSC prior to any observable impact on product potency. Detectable changes in oxidized methionine by mass spectrometry (MS) occurred at oxidation levels below those with a detectable conformational or functional impact. Therefore, by using MS, DSC, and relative potency methods in concert, the intricate relationship between a primary structural modification, changes in conformational stability, and functional impact can be elucidated.
NASA Astrophysics Data System (ADS)
Kupka, F.; Robinson, F. J.
2007-01-01
Non-local models of stellar convection usually rely on the assumption that the transfer of convective heat flux, turbulent kinetic energy and related quantities can be described as a diffusion process or that the fourth-order moments of velocity and temperature fluctuations follow a Gaussian distribution (quasi-normal approximation). The latter is also assumed in models of solar p-mode excitation. We have used realistic numerical simulations of solar granulation and of granulation in a K dwarf to test the quasi-normal approximation and several alternatives. For the superadiabatic layer of the Sun and for the quasi-adiabatic zone underneath, we find that the hypothesis of quasi-normality is a rather poor approximation. In the superadiabatic layer, it overestimates some of the fourth-order moments of vertical velocity and temperature by up to a factor of 2 while it underestimates them in the quasi-adiabatic layers by up to a factor of 3.5. The model proposed by Gryanik & Hartmann and Gryanik et al. reduces the discrepancies within the quasi-adiabatic zone to typically less than 30 per cent and is partially comparable and partially in better agreement with the simulation data than two earlier models by Grossman & Narayan. Simulation data for the K dwarf confirm these results. However, none of the proposed models works well in the superadiabatic layer nor in the photospheric layers above. For the Sun, we provide evidence that the fourth-order moments of horizontal velocity fields can be estimated to within about 30 per cent with the quasi-normal approximation despite the complexity of the horizontal flow. Comparing our results to those from solar simulations with idealized microphysics and with related studies of geophysical convection zones confirms our conclusions about the quasi-normal approximation and the new models. The improvements come from including the effects of coherent structures (such as granules or plumes), while the limitations are tied to the
ERIC Educational Resources Information Center
Canivez, Gary L.; Watkins, Marley W.
2010-01-01
The present study examined the factor structure of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; D. Wechsler, 2008a) standardization sample using exploratory factor analysis, multiple factor extraction criteria, and higher order exploratory factor analysis (J. Schmid & J. M. Leiman, 1957) not included in the WAIS-IV Technical…
Higher order mechanics on graded bundles
NASA Astrophysics Data System (ADS)
Bruce, Andrew James; Grabowska, Katarzyna; Grabowski, Janusz
2015-05-01
In this paper we develop a geometric approach to higher order mechanics on graded bundles in both, the Lagrangian and Hamiltonian formalism, via the recently discovered weighted algebroids. We present the corresponding Tulczyjew triple for this higher order situation and derive in this framework the phase equations from an arbitrary (also singular) Lagrangian or Hamiltonian, as well as the Euler-Lagrange equations. As important examples, we geometrically derive the classical higher order Euler-Lagrange equations and analogous reduced equations for invariant higher order Lagrangians on Lie groupoids.
Daneshmand, Farhang; Farokhi, Hamed; Amabili, Marco
2014-06-01
Microtubules in mammalian cells are cylindrical protein polymers which structurally and dynamically organize functional activities in living cells. They are important for maintaining cell structures, providing platforms for intracellular transport, and forming the spindle during mitosis, as well as other cellular processes. Various in vitro studies have shown that microtubules react to applied mechanical loading and physical environment. To investigate the mechanisms underlying such phenomena, a mathematical model based on the orthotropic higher-order shear deformation shell formulation and Hamilton's principle is presented in this paper for dynamic behavior of microtubules. The numerical results obtained by the proposed shell model are verified by the experimental data from the literature, showing great consistency. The nonlocal elasticity theory is also utilized to describe the nano-scale effects of the microtubule structure. The wave propagation and vibration characteristics of the microtubule are examined in the presence and absence of the cytosol employing proposed formulations. The effects of different system parameters such as length, small scale parameter, and cytosol viscosity on vibrational behavior of a microtubule are elucidated. The definitions of critical length and critical viscosity are introduced and the results obtained using the higher order shell model are compared with those obtained employing a first-order shear deformation theory. This comparison shows that the small scale effects become important for higher values of the wave vector and the proposed model gives more accurate results for both small and large values of wave vectors. Moreover, it is shown that for higher circumferential wave number, the torsional wave velocity obtained by the higher-order shell model tend to be higher than the one predicted by the first-order shell model.
Resonant radiation from oscillating higher order solitons
Driben, R.; Yulin, A. V.; Efimov, A.
2015-07-15
We present radiation mechanism exhibited by a higher order soliton. In a course of its evolution the higher-order soliton emits polychromatic radiation resulting in formation of multipeak frequency comb-like spectral band. The shape and spectral position of this band can be effectively controlled by the relative strength of the third order dispersion. An analytical description is corroborated by numerical simulations. Research showed that for longer pulses the described effect persists also under the action of higher order perturbations such as Raman and self-steepening.
ERIC Educational Resources Information Center
Golay, Philippe; Lecerf, Thierry
2011-01-01
According to the most widely accepted Cattell-Horn-Carroll (CHC) model of intelligence measurement, each subtest score of the Wechsler Intelligence Scale for Adults (3rd ed.; WAIS-III) should reflect both 1st- and 2nd-order factors (i.e., 4 or 5 broad abilities and 1 general factor). To disentangle the contribution of each factor, we applied a…
Higher-Order Factor Structure of the Differential Ability Scales-II: Consistency across Ages 4 to 17
ERIC Educational Resources Information Center
Keith, Timothy Z.; Low, Justin A.; Reynolds, Matthew R.; Patel, Puja G.; Ridley, Kristen P.
2010-01-01
The recently published second edition of the Differential Abilities Scale (DAS-II) is designed to measure multiple broad and general abilities from Cattell-Horn-Carroll (CHC) theory. Although the technical manual presents information supporting the test's structure, additional research is needed to determine the constructs measured by the test and…
Chawla, Mohit; Abdel-Azeim, Safwat; Oliva, Romina; Cavallo, Luigi
2014-01-01
The G:C reverse Watson-Crick (W:W trans) base pair, also known as Levitt base pair in the context of tRNAs, is a structurally and functionally important base pair that contributes to tertiary interactions joining distant domains in functional RNA molecules and also participates in metabolite binding in riboswitches. We previously indicated that the isolated G:C W:W trans base pair is a rather unstable geometry, and that dicationic metal binding to the Guanine base or posttranscriptional modification of the Guanine can increase its stability. Herein, we extend our survey and report on other H-bonding interactions that can increase the stability of this base pair. To this aim, we performed a bioinformatics search of the PDB to locate all the occurencies of G:C trans base pairs. Interestingly, 66% of the G:C trans base pairs in the PDB are engaged in additional H-bonding interactions with other bases, the RNA backbone or structured water molecules. High level quantum mechanical calculations on a data set of representative crystal structures were performed to shed light on the structural stability and energetics of the various crystallographic motifs. This analysis was extended to the binding of the preQ1 metabolite to a preQ1-II riboswitch.
Higher-order force gradient symplectic algorithms
NASA Astrophysics Data System (ADS)
Chin, Siu A.; Kidwell, Donald W.
2000-12-01
We show that a recently discovered fourth order symplectic algorithm, which requires one evaluation of force gradient in addition to three evaluations of the force, when iterated to higher order, yielded algorithms that are far superior to similarly iterated higher order algorithms based on the standard Forest-Ruth algorithm. We gauge the accuracy of each algorithm by comparing the step-size independent error functions associated with energy conservation and the rotation of the Laplace-Runge-Lenz vector when solving a highly eccentric Kepler problem. For orders 6, 8, 10, and 12, the new algorithms are approximately a factor of 103, 104, 104, and 105 better.
Mondal, Samiran; Begum, Nasim A.; Hu, Wenjun; Honjo, Tasuku
2016-01-01
Activation-induced cytidine deaminase (AID) is essential for the somatic hypermutation (SHM) and class-switch recombination (CSR) of Ig genes. Although both the N and C termini of AID have unique functions in DNA cleavage and recombination, respectively, during SHM and CSR, their molecular mechanisms are poorly understood. Using a bimolecular fluorescence complementation (BiFC) assay combined with glycerol gradient fractionation, we revealed that the AID C terminus is required for a stable dimer formation. Furthermore, AID monomers and dimers form complexes with distinct heterogeneous nuclear ribonucleoproteins (hnRNPs). AID monomers associate with DNA cleavage cofactor hnRNP K whereas AID dimers associate with recombination cofactors hnRNP L, hnRNP U, and Serpine mRNA-binding protein 1. All of these AID/ribonucleoprotein associations are RNA-dependent. We propose that AID’s structure-specific cofactor complex formations differentially contribute to its DNA-cleavage and recombination functions. PMID:26929374
Canivez, Gary L; Watkins, Marley W
2010-12-01
The present study examined the factor structure of the Wechsler Adult Intelligence Scale--Fourth Edition (WAIS-IV; D. Wechsler, 2008a) standardization sample using exploratory factor analysis, multiple factor extraction criteria, and higher order exploratory factor analysis (J. Schmid & J. M. Leiman, 1957) not included in the WAIS-IV Technical and Interpretation Manual (D. Wechsler, 2008b). Results indicated that the WAIS-IV subtests were properly associated with the theoretically proposed first-order factors, but all but one factor-extraction criterion recommended extraction of one or two factors. Hierarchical exploratory analyses with the Schmid and Leiman procedure found that the second-order g factor accounted for large portions of total and common variance, whereas the four first-order factors accounted for small portions of total and common variance. It was concluded that the WAIS-IV provides strong measurement of general intelligence, and clinical interpretation should be primarily at that level.
Tu, Xiongying; Palczewski, Krzysztof
2014-04-01
The C1q-tumor necrosis factor 5 (C1QTNF5) protein plays a significant role in retinal pigmented epithelium (RPE) cellular adhesion. The C1QTNF5 gene is co-transcribed with the frizzled-related protein (MFRP) gene. A Ser-to-Arg mutation at site 163 (S163R) in C1QTNF5 is known to cause late-onset retinal macular degeneration (L-ORMD). Here we also found that C1QTNF5 monomers can multimerize into a bouquet-like octadecamer. We found that a novel intermolecular hydrogen-bond network of S163 that glues adjacent globular heads of C1QTNF5 together was weakened or abolished by the R163 pathogenic mutation. These findings could underlie the structural basis of this protein's adhesive function and relate to the pathogenesis of its S163R mutation. Additionally, the fact that C1QTNF5 immobilized to a resin selectively enriched detergent extracted membrane-bound MFRP, further confirmed their interaction, implying functions other than cellular adhesion for C1QTNF5.
Tu, Xiongying; Palczewski, Krzysztof
2014-01-01
The C1q-tumor necrosis factor 5 (C1QTNF5) protein plays a significant role in retinal pigmented epithelium (RPE) cellular adhesion. The C1QTNF5 gene is co-transcribed with the frizzled-related protein (MFRP) gene. A Ser-to-Arg mutation at site 163 (S163R) in C1QTNF5 is known to cause late-onset retinal macular degeneration (L-ORMD). Here we also found that C1QTNF5 monomers can multimerize into a bouquet-like octadecamer. We found that a novel intermolecular hydrogen-bond network of S163 that glues adjacent globular heads of C1QTNF5 together and was weakened or abolished by the R163 pathogenic mutation. These findings could underlie the structural basis of this protein’s adhesive function and relate to the pathogenesis of its S163R mutation. Additionally, the fact that C1QTNF5 immobilized to a resin selectively enriched detergent extracted membrane-bound MFRP, further confirming their interaction and implying functions other than cellular adhesion for C1QTNF5. PMID:24531000
NASA Astrophysics Data System (ADS)
Amor, T. A.; Russo, R.; Diez, I.; Bharath, P.; Zirovich, M.; Stramaglia, S.; Cortes, J. M.; de Arcangelis, L.; Chialvo, D. R.
2015-09-01
The brain exhibits a wide variety of spatiotemporal patterns of neuronal activity recorded using functional magnetic resonance imaging as the so-called blood-oxygenated-level-dependent (BOLD) signal. An active area of work includes efforts to best describe the plethora of these patterns evolving continuously in the brain. Here we explore the third-moment statistics of the brain BOLD signals in the resting state as a proxy to capture extreme BOLD events. We find that the brain signal exhibits typically nonzero skewness, with positive values for cortical regions and negative values for subcortical regions. Furthermore, the combined analysis of structural and functional connectivity demonstrates that relatively more connected regions exhibit activity with high negative skewness. Overall, these results highlight the relevance of recent results emphasizing that the spatiotemporal location of the relatively large-amplitude events in the BOLD time series contains relevant information to reproduce a number of features of the brain dynamics during resting state in health and disease.
Higher-order phase shift reconstruction approach
Cong Wenxiang; Wang Ge
2010-10-15
Purpose: Biological soft tissues encountered in clinical and preclinical imaging mainly consists of atoms of light elements with low atomic numbers and their elemental composition is nearly uniform with little density variation. Hence, x-ray attenuation contrast is relatively poor and cannot achieve satisfactory sensitivity and specificity. In contrast, x-ray phase-contrast provides a new mechanism for soft tissue imaging. The x-ray phase shift of soft tissues is about a thousand times greater than the x-ray absorption over the diagnostic x-ray energy range, yielding a higher signal-to-noise ratio than the attenuation contrast counterpart. Thus, phase-contrast imaging is a promising technique to reveal detailed structural variation in soft tissues, offering a high contrast resolution between healthy and malignant tissues. Here the authors develop a novel phase retrieval method to reconstruct the phase image on the object plane from the intensity measurements. The reconstructed phase image is a projection of the phase shift induced by an object and serves as input to reconstruct the 3D refractive index distribution inside the object using a tomographic reconstruction algorithm. Such x-ray refractive index images can reveal structural features in soft tissues, with excellent resolution differentiating healthy and malignant tissues. Methods: A novel phase retrieval approach is proposed to reconstruct an x-ray phase image of an object based on the paraxial Fresnel-Kirchhoff diffraction theory. A primary advantage of the authors' approach is higher-order accuracy over that with the conventional linear approximation models, relaxing the current restriction of slow phase variation. The nonlinear terms in the autocorrelation equation of the Fresnel diffraction pattern are eliminated using intensity images measured at different distances in the Fresnel diffraction region, simplifying the phase reconstruction to a linear inverse problem. Numerical experiments are performed
Higher-Order Neural Networks Recognize Patterns
NASA Technical Reports Server (NTRS)
Reid, Max B.; Spirkovska, Lilly; Ochoa, Ellen
1996-01-01
Networks of higher order have enhanced capabilities to distinguish between different two-dimensional patterns and to recognize those patterns. Also enhanced capabilities to "learn" patterns to be recognized: "trained" with far fewer examples and, therefore, in less time than necessary to train comparable first-order neural networks.
Human motion perception: Higher-order organization
NASA Technical Reports Server (NTRS)
Kaiser, Mary K.; Proffitt, Dennis R.
1990-01-01
An overview is given of higher-order motion perception and organization. It is argued that motion is sufficient to fully specify a number of environmental properties, including: depth order, three-dimensional form, object displacement, and dynamics. A grammar of motion perception is proposed; applications of this work for display design are discussed.
Higher order organization of human placental aromatase.
Ghosh, Debashis; Jiang, Wenhua; Lo, Jessica; Egbuta, Chinaza
2011-07-01
Aromatase (CYP19A1) is an integral membrane enzyme that catalyzes the removal of the 19-methyl group and aromatization of the A-ring of androgens. All human estrogens are synthesized from their androgenic precursors by this unique cytochrome P450. The crystal structure of active aromatase purified from human placenta has recently been determined in complex with its natural substrate androstenedione in the high-spin ferric state of heme. Hydrogen bond forming interactions and tight packing hydrophobic side chains closely complement puckering of the steroid backbone, thereby providing the molecular basis for the androgenic specificity of aromatase. In the crystal, aromatase molecules are linked by a head-to-tail intermolecular interaction via a surface loop between helix D and helix E of one aromatase molecule that penetrates the heme-proximal cavity of the neighboring, crystallographically related molecule, thus forming in tandem a polymeric aromatase chain. This intermolecular interaction is similar to the aromatase-cytochrome P450 reductase coupling and is driven by electrostatics between the negative potential surface of the D-E loop region and the positively charged heme-proximal cavity. This loop-to-proximal site link in aromatase is rather unique--there are only a few of examples of somewhat similar intermolecular interactions in the entire P450 structure database. Furthermore, the amino acids involved in the intermolecular contact appear to be specific for aromatase. Higher order organization of aromatase monomers may have implications in lipid integration and catalysis.
Higher-order awareness, misrepresentation and function
Rosenthal, David
2012-01-01
Conscious mental states are states we are in some way aware of. I compare higher-order theories of consciousness, which explain consciousness by appeal to such higher-order awareness (HOA), and first-order theories, which do not, and I argue that higher-order theories have substantial explanatory advantages. The higher-order nature of our awareness of our conscious states suggests an analogy with the metacognition that figures in the regulation of psychological processes and behaviour. I argue that, although both consciousness and metacognition involve higher-order psychological states, they have little more in common. One thing they do share is the possibility of misrepresentation; just as metacognitive processing can misrepresent one's cognitive states and abilities, so the HOA in virtue of which one's mental states are conscious can, and sometimes does, misdescribe those states. A striking difference between the two, however, has to do with utility for psychological processing. Metacognition has considerable benefit for psychological processing; in contrast, it is unlikely that there is much, if any, utility to mental states' being conscious over and above the utility those states have when they are not conscious. PMID:22492758
Ausio, J; Borochov, N; Seger, D; Eisenberg, H
1984-08-15
Chicken erythrocyte chromatin containing histones H1 and H5 was carefully separated into a number of well-characterized fractions. A distinction could be made between chromatin insoluble in NaCl above about 80 mM, and chromatin soluble at all NaCl concentrations. Both chromatin forms were indistinguishable electrophoretically and both underwent the transition from the low salt "10 nm" coil to the "30 nm" higher-order structure solenoid by either raising the MgCl2 concentration to about 0.3 mM or the NaCl concentration to about 75 mM. The transitions were examined in detail by elastic light-scattering procedures. It could be shown that the 10 nm form is a flexible coil. For the 30 nm solenoid, the assumption of a rigid cylindrical structure was in good agreement with 5.7 nucleosomes per helical turn. However, disagreement of calculated frictional parameters with values derived from quasielastic light-scattering and sedimentation introduced the possibility that the higher-order structure, under these conditions, is more extended, flexible, or perhaps a mixture of structures. Values for density and refractive index increments of chromatin are also given. To understand the interaction of chromatin with NaCl and with MgCl2, a number of experiments were undertaken to study solubility, precipitation, conformational transitions and binding of ions over a wide range of experimental conditions, including chromatin concentration.
Weinert, Christopher; Morger, Damien; Djekic, Aleksandra; Grütter, Markus G; Mittl, Peer R E
2015-06-04
Many tripartite motif-containing (TRIM) proteins, comprising RING-finger, B-Box, and coiled-coil domains, carry additional B30.2 domains on the C-terminus of the TRIM motif and are considered to be pattern recognition receptors involved in the detection of higher order oligomers (e.g. viral capsid proteins). To investigate the spatial architecture of domains in TRIM proteins we determined the crystal structure of the TRIM20Δ413 fragment at 2.4 Å resolution. This structure comprises the central helical scaffold (CHS) and C-terminal B30.2 domains and reveals an anti-parallel arrangement of CHS domains placing the B-box domains 170 Å apart from each other. Small-angle X-ray scattering confirmed that the linker between CHS and B30.2 domains is flexible in solution. The crystal structure suggests an interaction between the B30.2 domain and an extended stretch in the CHS domain, which involves residues that are mutated in the inherited disease Familial Mediterranean Fever. Dimerization of B30.2 domains by means of the CHS domain is crucial for TRIM20 to bind pro-IL-1β in vitro. To exemplify how TRIM proteins could be involved in binding higher order oligomers we discuss three possible models for the TRIM5α/HIV-1 capsid interaction assuming different conformations of B30.2 domains.
Wang, Lei; Zhu, Yu-Jie; Qi, Feng-Hua; Li, Min; Guo, Rui
2015-06-01
In this paper, the nonautonomous Lenells-Fokas (LF) model is investigated. The modulational instability analysis of the solutions with variable coefficients in the presence of a small perturbation is studied. Higher-order soliton, breather, earthwormon, and rogue wave solutions of the nonautonomous LF model are derived via the n-fold variable-coefficient Darboux transformation. The solitons and earthwormons display the elastic collisions. It is found that the nonautonomous LF model admits the higher-order periodic rogue waves, composite rogue waves (rogue wave pair), and oscillating rogue waves, whose dynamics can be controlled by the inhomogeneous nonlinear parameters. Based on the second-order rogue wave, a diamond structure consisting of four first-order rogue waves is observed. In addition, the semirational solutions (the mixed rational-exponential solutions) of the nonautonomous LF model are obtained, which can be used to describe the interactions between the rogue waves and breathers. Our results could be helpful for the design of experiments in the optical fiber communications.
Higher Order Thinking in the Dance Studio
ERIC Educational Resources Information Center
Moffett, Ann-Thomas
2012-01-01
The author identifies higher order thinking as an essential component of dance training for students of all ages and abilities. Weaving together insights from interviews with experts in the field of dance education with practical pedagogical applications within an Improvisation and Composition class for talented and gifted youth, this article…
Assessing Higher Order Thinking in Mathematics.
ERIC Educational Resources Information Center
Kulm, Gerald, Ed.
This book explores current theory, research, practice, and policy in the assessment of higher order thinking in mathematics, focusing on the elementary and secondary grades. Current knowledge and research on mathematics learning and testing is synthesized. Examples of innovative test items for classroom use and state assessment programs are…
Performance assessment of higher order thinking.
Griffin, Patrick
2014-01-01
This article describes a study investigating the effect of intervention on student problem solving and higher order competency development using a series of complex numeracy performance tasks (Airasian and Russell, 2008). The tasks were sequenced to promote and monitor student development towards hypothetico-deductive reasoning. Using Rasch partial credit analysis (Wright and Masters, 1982) to calibrate the tasks and analysis of residual gain scores to examine the effect of class and school membership, the study illustrates how directed intervention can improve students' higher order competency skills. This paper demonstrates how the segmentation defined by Wright and Masters can offer a basis for interpreting the construct underlying a test and how segment definitions can deliver targeted interventions. Implications for teacher intervention and teaching mentor schemes are considered. The article also discusses multilevel regression models that differentiate class and school effects, and describes a process for generating, testing and using value added models.
Random interactions in higher order neural networks
NASA Technical Reports Server (NTRS)
Baldi, Pierre; Venkatesh, Santosh S.
1993-01-01
Recurrent networks of polynomial threshold elements with random symmetric interactions are studied. Precise asymptotic estimates are derived for the expected number of fixed points as a function of the margin of stability. In particular, it is shown that there is a critical range of margins of stability (depending on the degree of polynomial interaction) such that the expected number of fixed points with margins below the critical range grows exponentially with the number of nodes in the network, while the expected number of fixed points with margins above the critical range decreases exponentially with the number of nodes in the network. The random energy model is also briefly examined and links with higher order neural networks and higher order spin glass models made explicit.
Higher-order mode photonic crystal based nanofluidic sensor
NASA Astrophysics Data System (ADS)
Peng, Wang; Chen, Youping; Ai, Wu
2017-01-01
A higher-order photonic crystal (PC) based nanofluidic sensor, which worked at 532 nm, was designed and demonstrated. A systematical and detailed method for sculpturing a PC sensor for a given peak wavelength value (PWV) and specified materials was illuminated. It was the first time that the higher order mode was used to design PC based nanofluidic sensor, and the refractive index (RI) sensitivity of this sensor had been verified with FDTD simulation software from Lumerical. The enhanced electrical field of higher order mode structure was mostly confined in the channel area, where the enhance field is wholly interacting with the analytes in the channels. The comparison of RI sensitivity between fundamental mode and higher order mode shows the RI variation of higher order mode is 124.5 nm/RIU which is much larger than the fundamental mode. The proposed PC based nanofluidic structure pioneering a novel style for future optofluidic design.
Higher-Order Mentalising and Executive Functioning
2015-01-01
Higher-order mentalising is the ability to represent the beliefs and desires of other people at multiple, iterated levels – a capacity that sets humans apart from other species. However, there has not yet been a systematic attempt to determine what cognitive processes underlie this ability. Here we present three correlational studies assessing the extent to which performance on higher-order mentalising tasks relates to emotion recognition, self-reported empathy and self-inhibition. In Study 1a and 1b, examining emotion recognition and empathy, a relationship was identified between individual differences in the ability to mentalise and an emotion recognition task (the Reading the Mind in the Eyes task), but no correlation was found with the Empathy Quotient, a self-report scale of empathy. Study 2 investigated whether a relationship exists between individual mentalising abilities and four different forms of self-inhibition: motor inhibition, executive inhibition, automatic imitation and temporal discounting. Results demonstrate that only temporal discounting performance relates to mentalising ability; suggesting that cognitive skills relevant to representation of the minds of others’ are not influenced by the ability to perform more basic inhibition. Higher-order mentalising appears to rely on the cognitive architecture that serves both low-level social cognition (emotion recognition), and complex forms of inhibition. PMID:26543298
Higher-Order Mentalising and Executive Functioning.
2015-11-01
Higher-order mentalising is the ability to represent the beliefs and desires of other people at multiple, iterated levels - a capacity that sets humans apart from other species. However, there has not yet been a systematic attempt to determine what cognitive processes underlie this ability. Here we present three correlational studies assessing the extent to which performance on higher-order mentalising tasks relates to emotion recognition, self-reported empathy and self-inhibition. In Study 1a and 1b, examining emotion recognition and empathy, a relationship was identified between individual differences in the ability to mentalise and an emotion recognition task (the Reading the Mind in the Eyes task), but no correlation was found with the Empathy Quotient, a self-report scale of empathy. Study 2 investigated whether a relationship exists between individual mentalising abilities and four different forms of self-inhibition: motor inhibition, executive inhibition, automatic imitation and temporal discounting. Results demonstrate that only temporal discounting performance relates to mentalising ability; suggesting that cognitive skills relevant to representation of the minds of others' are not influenced by the ability to perform more basic inhibition. Higher-order mentalising appears to rely on the cognitive architecture that serves both low-level social cognition (emotion recognition), and complex forms of inhibition.
NASA Technical Reports Server (NTRS)
Pindera, Marek-Jerzy; Aboudi, Jacob
2000-01-01
The objective of this two-year project was to develop and deliver to the NASA-Glenn Research Center a two-dimensional higher-order theory, and related computer codes, for the analysis and design of cylindrical functionally graded materials/structural components for use in advanced aircraft engines (e.g., combustor linings, rotor disks, heat shields, brisk blades). To satisfy this objective, two-dimensional version of the higher-order theory, HOTCFGM-2D, and four computer codes based on this theory, for the analysis and design of structural components functionally graded in the radial and circumferential directions were developed in the cylindrical coordinate system r-Theta-z. This version of the higher-order theory is a significant generalization of the one-dimensional theory, HOTCFGM-1D, developed during the FY97 for the analysis and design of cylindrical structural components with radially graded microstructures. The generalized theory is applicable to thin multi-phased composite shells/cylinders subjected to steady-state thermomechanical, transient thermal and inertial loading applied uniformly along the axial direction such that the overall deformation is characterized by a constant average axial strain. The reinforcement phases are uniformly distributed in the axial direction, and arbitrarily distributed in the radial and circumferential direction, thereby allowing functional grading of the internal reinforcement in the r-Theta plane. The four computer codes fgmc3dq.cylindrical.f, fgmp3dq.cylindrical.f, fgmgvips3dq.cylindrical.f, and fgmc3dq.cylindrical.transient.f are research-oriented codes for investigating the effect of functionally graded architectures, as well as the properties of the multi-phase reinforcement, in thin shells subjected to thermomechanical and inertial loading, on the internal temperature, stress and (inelastic) strain fields. The reinforcement distribution in the radial and circumferential directions is specified by the user. The thermal
Miskei, Marton; Antal, Csaba; Fuxreiter, Monika
2017-01-01
FuzDB (http://protdyn-database.org) compiles experimentally observed fuzzy protein complexes, where intrinsic disorder (ID) is maintained upon interacting with a partner (protein, nucleic acid or small molecule) and directly impacts biological function. Entries in the database have both (i) structural evidence demonstrating the structural multiplicity or dynamic disorder of the ID region(s) in the partner bound form of the protein and (ii) in vitro or in vivo biological evidence that indicates the significance of the fuzzy region(s) in the formation, function or regulation of the assembly. Unlike the other intrinsically disordered or unfolded protein databases, FuzDB focuses on ID regions within a biological context, including higher-order assemblies and presents a detailed analysis of the structural and functional data. FuzDB also provides interpretation of experimental results to elucidate the molecular mechanisms by which fuzzy regions—classified on the basis of topology and mechanism—interfere with the structural ensembles and activity of protein assemblies. Regulatory sites generated by alternative splicing (AS) or post-translational modifications (PTMs) are also collected. By assembling all this information, FuzDB could be utilized to develop stochastic structure–function relationships for proteins and could contribute to the emergence of a new paradigm. PMID:27794553
Al-Majdoub, M; Opuni, K F M; Koy, C; Glocker, M O
2013-11-05
Both epitope excision and epitope extraction methods, combined with mass spectrometry, generate precise informations on binding surfaces of full-length proteins, identifying sequential (linear) or assembled (conformational) epitopes, respectively. Here, we describe the one-step fabrication and application of affinity columns using reversibly immobilized antibodies with highest flexibility with respect to antibody sources and lowest sample amount requirements (fmol range). Depending on the antibody source, we made use of protein G- or protein A-coated resins as support materials. These materials are packed in pipet tips and in combination with a programmable multichannel pipet form a highly efficient epitope mapping system. In addition to epitope identification, the influence of epitope structure modifications on antibody binding specificities could be studied in detail with synthetic peptides. Elution of epitope peptides was optimized such that mass spectrometric analysis was feasible after a single desalting step. Epitope peptides were identified by accurate molecular mass determinations or by partial amino acid sequence analysis. In addition, charge state comparison or ion mobility analysis of eluted epitope peptides enabled investigation of higher-order structures. The epitope peptide of the TRIM21 (TRIM: tripartite motif) autoantigen that is recognized by a polyclonal antibody was determined as assembling an "L-E-Q-L" motif on an α-helix. Secondary structure determination by circular dichroism spectroscopy and structure modeling are in accordance with the mass spectrometric results and the antigenic behavior of the 17-mer epitope peptide variants from the full-length autoantigen.
Visualizing higher order finite elements. Final report
Thompson, David C; Pebay, Philippe Pierre
2005-11-01
This report contains an algorithm for decomposing higher-order finite elements into regions appropriate for isosurfacing and proves the conditions under which the algorithm will terminate. Finite elements are used to create piecewise polynomial approximants to the solution of partial differential equations for which no analytical solution exists. These polynomials represent fields such as pressure, stress, and momentum. In the past, these polynomials have been linear in each parametric coordinate. Each polynomial coefficient must be uniquely determined by a simulation, and these coefficients are called degrees of freedom. When there are not enough degrees of freedom, simulations will typically fail to produce a valid approximation to the solution. Recent work has shown that increasing the number of degrees of freedom by increasing the order of the polynomial approximation (instead of increasing the number of finite elements, each of which has its own set of coefficients) can allow some types of simulations to produce a valid approximation with many fewer degrees of freedom than increasing the number of finite elements alone. However, once the simulation has determined the values of all the coefficients in a higher-order approximant, tools do not exist for visual inspection of the solution. This report focuses on a technique for the visual inspection of higher-order finite element simulation results based on decomposing each finite element into simplicial regions where existing visualization algorithms such as isosurfacing will work. The requirements of the isosurfacing algorithm are enumerated and related to the places where the partial derivatives of the polynomial become zero. The original isosurfacing algorithm is then applied to each of these regions in turn.
Representing higher-order dependencies in networks
Xu, Jian; Wickramarathne, Thanuka L.; Chawla, Nitesh V.
2016-01-01
To ensure the correctness of network analysis methods, the network (as the input) has to be a sufficiently accurate representation of the underlying data. However, when representing sequential data from complex systems, such as global shipping traffic or Web clickstream traffic as networks, conventional network representations that implicitly assume the Markov property (first-order dependency) can quickly become limiting. This assumption holds that, when movements are simulated on the network, the next movement depends only on the current node, discounting the fact that the movement may depend on several previous steps. However, we show that data derived from many complex systems can show up to fifth-order dependencies. In these cases, the oversimplifying assumption of the first-order network representation can lead to inaccurate network analysis results. To address this problem, we propose the higher-order network (HON) representation that can discover and embed variable orders of dependencies in a network representation. Through a comprehensive empirical evaluation and analysis, we establish several desirable characteristics of HON, including accuracy, scalability, and direct compatibility with the existing suite of network analysis methods. We illustrate how HON can be applied to a broad variety of tasks, such as random walking, clustering, and ranking, and we demonstrate that, by using it as input, HON yields more accurate results without any modification to these tasks. PMID:27386539
Higher Order Equations and Constituent Fields
NASA Astrophysics Data System (ADS)
Barci, D. G.; Bollini, C. G.; Oxman, L. E.; Rocca, M.
We consider a simple wave equation of fourth degree in the D'Alembertian operator. It contains the main ingredients of a general Lorentz-invariant higher order equation, namely, a normal bradyonic sector, a tachyonic state and a pair of complex conjugate modes. The propagators are respectively the Feynman causal function and three Wheeler-Green functions (half-advanced and half-retarded). The latter are Lorentz-invariant and consistent with the elimination of tachyons and complex modes from free asymptotic states. We also verify the absence of absorptive parts from convolutions involving Wheeler propagators.
Theorem Proving In Higher Order Logics
NASA Technical Reports Server (NTRS)
Carreno, Victor A. (Editor); Munoz, Cesar A.; Tahar, Sofiene
2002-01-01
The TPHOLs International Conference serves as a venue for the presentation of work in theorem proving in higher-order logics and related areas in deduction, formal specification, software and hardware verification, and other applications. Fourteen papers were submitted to Track B (Work in Progress), which are included in this volume. Authors of Track B papers gave short introductory talks that were followed by an open poster session. The FCM 2002 Workshop aimed to bring together researchers working on the formalisation of continuous mathematics in theorem proving systems with those needing such libraries for their applications. Many of the major higher order theorem proving systems now have a formalisation of the real numbers and various levels of real analysis support. This work is of interest in a number of application areas, such as formal methods development for hardware and software application and computer supported mathematics. The FCM 2002 consisted of three papers, presented by their authors at the workshop venue, and one invited talk.
A Model for the National Assessment of Higher Order Thinking.
ERIC Educational Resources Information Center
Paul, Richard; Nosich, Gerald M.
This document provides a model for the national assessment of higher order thinking and consists of a preface and four main sections. The preface discusses the problem of lower order learning, summarizes the state of research into critical thinking and instructional reform, and explains the structure of the paper. Section 1 of the paper describes…
Heidrich, Jennifer; Wulf, Verena; Hennig, Raoul; Saur, Michael; Markl, Jürgen; Sönnichsen, Carsten; Schneider, Dirk
2016-07-15
The IM30 (inner membrane-associated protein of 30 kDa), also known as the Vipp1 (vesicle-inducing protein in plastids 1), has a crucial role in thylakoid membrane biogenesis and maintenance. Recent results suggest that the protein binds peripherally to membranes containing negatively charged lipids. However, although IM30 monomers interact and assemble into large oligomeric ring complexes with different numbers of monomers, it is still an open question whether ring formation is crucial for membrane interaction. Here we show that binding of IM30 rings to negatively charged phosphatidylglycerol membrane surfaces results in a higher ordered membrane state, both in the head group and in the inner core region of the lipid bilayer. Furthermore, by using gold nanorods covered with phosphatidylglycerol layers and single particle spectroscopy, we show that not only IM30 rings but also lower oligomeric IM30 structures interact with membranes, although with higher affinity. Thus, ring formation is not crucial for, and even counteracts, membrane interaction of IM30.
Wang, Xiaodong; Hayes, Jeffrey J
2008-01-01
Nucleosome arrays undergo salt-dependent self-association into large oligomers in a process thought to recapitulate essential aspects of higher-order tertiary chromatin structure formation. Lysine acetylation within the core histone tail domains inhibits self-association, an effect likely related to its role in facilitating transcription. As acetylation of specific tail domains may encode distinct functions, we investigated biochemical and self-association properties of model nucleosome arrays containing combinations of native and mutant core histones with lysine-to-glutamine substitutions to mimic acetylation. Acetylation mimics within the tail domains of H2B and H4 caused the largest inhibition of array self-association, while modification of the H3 tail uniquely affected the stability of DNA wrapping within individual nucleosomes. In addition, the effect of acetylation mimics on array self-association is inconsistent with a simple charge neutralization mechanism. For example, acetylation mimics within the H2A tail can have either a positive or negative effect on self-association, dependent upon the acetylation state of the other tails and nucleosomal repeat length. Finally, we demonstrate that glutamine substitutions and lysine acetylation within the H4 tail domain have identical effects on nucleosome array self-association. Our results indicate that acetylation of specific tail domains plays distinct roles in the regulation of chromatin structure.
Silva-Santiago, Evangelina; Pardo, Juan Pablo; Hernández-Muñoz, Rolando; Aranda-Anzaldo, Armando
2017-01-15
During the interphase the nuclear DNA of metazoan cells is organized in supercoiled loops anchored to constituents of a nuclear substructure or compartment known as the nuclear matrix. The stable interactions between DNA and the nuclear matrix (NM) correspond to a set of topological relationships that define a nuclear higher-order structure (NHOS). Current evidence suggests that the NHOS is cell-type-specific. Biophysical evidence and theoretical models suggest that thermodynamic and structural constraints drive the actualization of DNA-NM interactions. However, if the topological relationships between DNA and the NM were the subject of any biological constraint with functional significance then they must be adaptive and thus be positively selected by natural selection and they should be reasonably conserved, at least within closely related species. We carried out a coarse-grained, comparative evaluation of the DNA-NM topological relationships in primary hepatocytes from two closely related mammals: rat and mouse, by determining the relative position to the NM of a limited set of target sequences corresponding to highly-conserved genomic regions that also represent a sample of distinct chromosome territories within the interphase nucleus. Our results indicate that the pattern of topological relationships between DNA and the NM is not conserved between the hepatocytes of the two closely related species, suggesting that the NHOS, like the karyotype, is species-specific.
Higher order correlations of IRAS galaxies
NASA Technical Reports Server (NTRS)
Meiksin, Avery; Szapudi, Istvan; Szalay, Alexander
1992-01-01
The higher order irreducible angular correlation functions are derived up to the eight-point function, for a sample of 4654 IRAS galaxies, flux-limited at 1.2 Jy in the 60 microns band. The correlations are generally found to be somewhat weaker than those for the optically selected galaxies, consistent with the visual impression of looser clusters in the IRAS sample. It is found that the N-point correlation functions can be expressed as the symmetric sum of products of N - 1 two-point functions, although the correlations above the four-point function are consistent with zero. The coefficients are consistent with the hierarchical clustering scenario as modeled by Hamilton and by Schaeffer.
Aspects of general higher-order gravities
NASA Astrophysics Data System (ADS)
Bueno, Pablo; Cano, Pablo A.; Min, Vincent S.; Visser, Manus R.
2017-02-01
We study several aspects of higher-order gravities constructed from general contractions of the Riemann tensor and the metric in arbitrary dimensions. First, we use the fast-linearization procedure presented in [P. Bueno and P. A. Cano, arXiv:1607.06463] to obtain the equations satisfied by the metric perturbation modes on a maximally symmetric background in the presence of matter and to classify L (Riemann ) theories according to their spectrum. Then, we linearize all theories up to quartic order in curvature and use this result to construct quartic versions of Einsteinian cubic gravity. In addition, we show that the most general cubic gravity constructed in a dimension-independent way and which does not propagate the ghostlike spin-2 mode (but can propagate the scalar) is a linear combination of f (Lovelock ) invariants, plus the Einsteinian cubic gravity term, plus a new ghost-free gravity term. Next, we construct the generalized Newton potential and the post-Newtonian parameter γ for general L (Riemann ) gravities in arbitrary dimensions, unveiling some interesting differences with respect to the four-dimensional case. We also study the emission and propagation of gravitational radiation from sources for these theories in four dimensions, providing a generalized formula for the power emitted. Finally, we review Wald's formalism for general L (Riemann ) theories and construct new explicit expressions for the relevant quantities involved. Many examples illustrate our calculations.
Higher Order Fractional Stable Motion: Hyperdiffusion with Heavy Tails
NASA Astrophysics Data System (ADS)
Kawai, Reiichiro
2016-10-01
We introduce the class of higher order fractional stable motions that can exhibit hyperdiffusive spreading with heavy tails. We define the class as a generalization of higher order fractional Brownian motion as well as a generalization of linear fractional stable motions. Higher order fractional stable motions are self-similar with Hurst index larger than one and non-Gaussian stable marginals with infinite variance and have stationary higher order increments. We investigate their sample path properties and asymptotic dependence structure on the basis of codifference. In particular, by incrementing or decrementing sample paths once under suitable conditions, the diffusion rate can be accelerated or decelerated by one order. With a view towards simulation study, we provide a ready-for-use sample path simulation recipe at discrete times along with error analysis. The proposed simulation scheme requires only elementary numerical operations and is robust to high frequency sampling, irregular spacing and super-sampling.
Raderschall, Elke; Bazarov, Alex; Cao, Jiangping; Lurz, Rudi; Smith, Avril; Mann, Wolfgang; Ropers, Hans-Hilger; Sedivy, John M; Golub, Efim I; Fritz, Eberhard; Haaf, Thomas
2002-01-01
After exposure of mammalian cells to DNA damage, the endogenous Rad51 recombination protein is concentrated in multiple discrete foci, which are thought to represent nuclear domains for recombinational DNA repair. Overexpressed Rad51 protein forms foci and higher-order nuclear structures, even in the absence of DNA damage, in cells that do not undergo DNA replication synthesis. This correlates with increased expression of the cyclin-dependent kinase (Cdk) inhibitor p21. Following DNA damage, constitutively Rad51-overexpressing cells show reduced numbers of DNA breaks and chromatid-type chromosome aberrations and a greater resistance to apoptosis. In contrast, Rad51 antisense inhibition reduces p21 protein levels and sensitizes cells to etoposide treatment. Downregulation of p21 inhibits Rad51 foci formation in both normal and Rad51-overexpressing cells. Collectively, our results show that Rad51 expression, Rad51 foci formation and p21 expression are interrelated, suggesting a functional link between mammalian Rad51 protein and p21-mediated cell cycle regulation. This mechanism may contribute to a highly effective recombinational DNA repair in cell cycle-arrested cells and protection against DNA damage-induced apoptosis.
Aged and post-mitotic cells share a very stable higher-order structure in the cell nucleus in vivo.
Alva-Medina, Janeth; Dent, Myrna A R; Aranda-Anzaldo, Armando
2010-12-01
In the mammalian liver the quiescent primary hepatocytes preserve a proliferating potential in vivo, yet natural aging correlates with loss of proliferating potential and progression towards terminal differentiation of the hepatocytes. Thus aged, terminally-differentiated hepatocytes may survive in a de facto post-mitotic state, similarly to early post-mitotic cells, like neurons, suggesting that there might be a common factor linking both cellular states. In the interphase of metazoan cells the nuclear DNA is organized in supercoiled loops anchored to a proteinaceous substructure known as the nuclear matrix (NM). The DNA-NM interactions define a higher-order structure in the cell nucleus (NHOS). Natural aging of the rat liver correlates with a progressive strengthening of the NM framework and the stabilization of the DNA-NM interactions in the hepatocytes indicating that the NHOS becomes highly stable with age. We compared the NHOS of post-mitotic rat neurons with that of aged rat hepatocytes. Our results indicate that a very stable NHOS is a common feature of both aged and post-mitotic cells in vivo.
ERIC Educational Resources Information Center
Chen, Chin-Yi; Michael, William B.
1993-01-01
Empirical validation of the first-order and higher-order factor structures of the structure-of-intellect (SOI) model was provided by reanalysis of a database of 39 measures administered to 178 Coast Guard Cadets. Results suggest that SOI could be reconceptualized as a pyramid-like hierarchical theory of intelligence. (SLD)
NASA Astrophysics Data System (ADS)
McGowan, L. E.; Dahlke, H. E.; Paw U, K. T.
2015-12-01
Snow cover is a critical driver of the Earth's surface energy budget, climate change, and water resources. Variations in snow cover not only affect the energy budget of the land surface but also represent a major water supply source. In California, US estimates of snow depth, extent, and melt in the Sierra Nevada are critical to estimating the amount of water available for both California agriculture and urban users. However, accurate estimates of snow cover and snow melt processes in forested area still remain a challenge. Canopy structure influences the vertical and spatiotemporal distribution of snow, and therefore ultimately determines the degree and extent by which snow alters both the surface energy balance and water availability in forested regions. In this study we use the Advanced Canopy-Atmosphere-Soil algorithm (ACASA), a multi-layer soil-vegetation-atmosphere numerical model, to simulate the effect of different snow-covered canopy structures on the energy budget, and temperature and other scalar profiles within different forest types in the Sierra Nevada, California. ACASA incorporates a higher order turbulence closure scheme which allows the detailed simulation of turbulent fluxes of heat and water vapor as well as the CO2 exchange of several layers within the canopy. As such ACASA can capture the counter gradient fluxes within canopies that may occur frequently, but are typically unaccounted for, in most snow hydrology models. Six different canopy types were modeled ranging from coniferous forests (e.g. most biomass near the ground) to top-heavy (e.g. most biomass near the top of the crown) deciduous forests to multi-layered forest canopies (e.g. mixture of young and mature trees). Preliminary results indicate that the canopy shape and structure associated with different canopy types fundamentally influence the vertical scalar profiles (including those of temperature, moisture, and wind speed) in the canopy and thus alter the interception and snow
Constructing higher-order hydrodynamics: The third order
NASA Astrophysics Data System (ADS)
Grozdanov, Sašo; Kaplis, Nikolaos
2016-03-01
Hydrodynamics can be formulated as the gradient expansion of conserved currents in terms of the fundamental fields describing the near-equilibrium fluid flow. In the relativistic case, the Navier-Stokes equations follow from the conservation of the stress-energy tensor to first order in derivatives. In this paper, we go beyond the presently understood second-order hydrodynamics and discuss the systematization of obtaining the hydrodynamic expansion to an arbitrarily high order. As an example of the algorithm that we present, we fully classify the gradient expansion at third order for neutral fluids in four dimensions, thus finding the most general next-to-leading-order corrections to the relativistic Navier-Stokes equations in curved space-time. In doing so, we list 20 new transport coefficient candidates in the conformal case and 68 in the nonconformal case. As we do not consider any constraints that could potentially arise from the local entropy current analysis, this is the maximal possible set of neutral third-order transport coefficients. To investigate the physical implications of these new transport coefficients, we obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We also compute the corrections to the scalar (spin-2) two-point correlation function of the third-order stress-energy tensor. Furthermore, as an example of a nonlinear hydrodynamic flow, we calculate the third-order corrections to the energy density of a boost-invariant Bjorken flow. Finally, we apply our field theoretic results to the N =4 supersymmetric Yang-Mills fluid at infinite 't Hooft coupling and an infinite number of colors to find the values of five new linear combinations of the conformal transport coefficients.
Higher-Order Item Response Models for Hierarchical Latent Traits
ERIC Educational Resources Information Center
Huang, Hung-Yu; Wang, Wen-Chung; Chen, Po-Hsi; Su, Chi-Ming
2013-01-01
Many latent traits in the human sciences have a hierarchical structure. This study aimed to develop a new class of higher order item response theory models for hierarchical latent traits that are flexible in accommodating both dichotomous and polytomous items, to estimate both item and person parameters jointly, to allow users to specify…
Modeling Higher-Order Correlations within Cortical Microcolumns
Köster, Urs; Sohl-Dickstein, Jascha; Gray, Charles M.; Olshausen, Bruno A.
2014-01-01
We statistically characterize the population spiking activity obtained from simultaneous recordings of neurons across all layers of a cortical microcolumn. Three types of models are compared: an Ising model which captures pairwise correlations between units, a Restricted Boltzmann Machine (RBM) which allows for modeling of higher-order correlations, and a semi-Restricted Boltzmann Machine which is a combination of Ising and RBM models. Model parameters were estimated in a fast and efficient manner using minimum probability flow, and log likelihoods were compared using annealed importance sampling. The higher-order models reveal localized activity patterns which reflect the laminar organization of neurons within a cortical column. The higher-order models also outperformed the Ising model in log-likelihood: On populations of 20 cells, the RBM had 10% higher log-likelihood (relative to an independent model) than a pairwise model, increasing to 45% gain in a larger network with 100 spatiotemporal elements, consisting of 10 neurons over 10 time steps. We further removed the need to model stimulus-induced correlations by incorporating a peri-stimulus time histogram term, in which case the higher order models continued to perform best. These results demonstrate the importance of higher-order interactions to describe the structure of correlated activity in cortical networks. Boltzmann Machines with hidden units provide a succinct and effective way to capture these dependencies without increasing the difficulty of model estimation and evaluation. PMID:24991969
Modeling higher-order correlations within cortical microcolumns.
Köster, Urs; Sohl-Dickstein, Jascha; Gray, Charles M; Olshausen, Bruno A
2014-07-01
We statistically characterize the population spiking activity obtained from simultaneous recordings of neurons across all layers of a cortical microcolumn. Three types of models are compared: an Ising model which captures pairwise correlations between units, a Restricted Boltzmann Machine (RBM) which allows for modeling of higher-order correlations, and a semi-Restricted Boltzmann Machine which is a combination of Ising and RBM models. Model parameters were estimated in a fast and efficient manner using minimum probability flow, and log likelihoods were compared using annealed importance sampling. The higher-order models reveal localized activity patterns which reflect the laminar organization of neurons within a cortical column. The higher-order models also outperformed the Ising model in log-likelihood: On populations of 20 cells, the RBM had 10% higher log-likelihood (relative to an independent model) than a pairwise model, increasing to 45% gain in a larger network with 100 spatiotemporal elements, consisting of 10 neurons over 10 time steps. We further removed the need to model stimulus-induced correlations by incorporating a peri-stimulus time histogram term, in which case the higher order models continued to perform best. These results demonstrate the importance of higher-order interactions to describe the structure of correlated activity in cortical networks. Boltzmann Machines with hidden units provide a succinct and effective way to capture these dependencies without increasing the difficulty of model estimation and evaluation.
Higher order vortex methods with rezoning
NASA Astrophysics Data System (ADS)
Nordmark, H. O.
1988-05-01
The vortex method is a numerical method for approximating the flow of an incompressible, inviscid fluid. We consider the two-dimensional case. The accuracy depends on the choice of the cutoff function which approximates the delta function, on the cutoff parameter delta and on the smoothness of the initial data. We derive a class of infinite-order cutoff functions with arbitrarily high rates of decay at infinity. We also derive an eighth order cutoff function with compact support. We test two versions of rezoning. Version 1 has been suggested and tested by Beale and Majda, while version 2 is new. Using rezoning, we test the eighth order cutoff function and one infinite-order cutoff function on three test problems for which the solution of Euler's equation is known analytically. The accuracies of the two methods are comparable. We also compute the evolution of two circular vorticity patches and the evolution of one square vorticity patch over long time intervals. Finally, we make a comparison between the direct method of velocity evaluation and the Rokhlin-Greengard algorithm. The numerical experiments indicate that for smooth flows, high-order cutoffs combined with rezoning give high accuracy for long time integrations.
Tachyons and Higher Order Wave Equations
NASA Astrophysics Data System (ADS)
Barci, D. G.; Bollini, C. G.; Rocca, M. C.
We consider a fourth order wave equation having normal as well as tachyonic solutions. The propagators are, respectively, the Feynman causal function and the Wheeler-Green function (half advanced and half retarded). The latter is consistent with the elimination of tachyons from free asymptotic states. We verify the absence of absorptive parts from convolutions involving the tachyon propagator.
Small Schools and Higher Order Thinking Skills.
ERIC Educational Resources Information Center
Haller, Emil J.; And Others
A review of the literature indicates that, compared to larger, urban schools, small, rural secondary schools have limited course offerings in mathematics and science; the review also indicates, however, that the achievement of students in small, rural schools is equivalent to or even higher than, that of students in larger, urban schools. Such an…
Entanglement equilibrium for higher order gravity
NASA Astrophysics Data System (ADS)
Bueno, Pablo; Min, Vincent S.; Speranza, Antony J.; Visser, Manus R.
2017-02-01
We show that the linearized higher derivative gravitational field equations are equivalent to an equilibrium condition on the entanglement entropy of small spherical regions in vacuum. This extends Jacobson's recent derivation of the Einstein equation using entanglement to include general higher derivative corrections. The corrections are naturally associated with the subleading divergences in the entanglement entropy, which take the form of a Wald entropy evaluated on the entangling surface. Variations of this Wald entropy are related to the field equations through an identity for causal diamonds in maximally symmetric spacetimes, which we derive for arbitrary higher derivative theories. If the variations are taken holding fixed a geometric functional that we call the generalized volume, the identity becomes an equivalence between the linearized constraints and the entanglement equilibrium condition. We note that the fully nonlinear higher curvature equations cannot be derived from the linearized equations applied to small balls, in contrast to the situation encountered in Einstein gravity. The generalized volume is a novel result of this work, and we speculate on its thermodynamic role in the first law of causal diamond mechanics, as well as its possible application to holographic complexity.
Higher order diffractions from a circular disk
NASA Technical Reports Server (NTRS)
Marsland, Diane P.; Balanis, Constantine A.; Brumley, Stephen A.
1987-01-01
The backscattering from a circular disk is analyzed using the geometrical theory of diffraction. First-, second-, and third-order diffractions are included in the hard polarization analysis, while first-, second-, and third-order slope diffractions are included for soft polarization. Improvements in the prediction of the monostatic radar cross section over previous works are noted. For hard polarization, an excellent agreement is exhibited between experimental and theoretical results, while a very good agreement is noted for soft polarization. To further improve the soft polarization results for wide angles, a model for the creeping wave or circulating current on the edge of the disk is obtained and used to find an additional component of the backscattered field. The addition of this component significantly improves the results for wide angles, leading to excellent agreement for soft polarization also. An axial-caustic correction method using equivalent currents is also included in the analysis.
Recent Advances in Higher-Order, Multimodal, Biomedical Imaging Agents.
Rieffel, James; Chitgupi, Upendra; Lovell, Jonathan F
2015-09-16
Advances in biomedical imaging have spurred the development of integrated multimodal scanners, usually capable of two simultaneous imaging modes. The long-term vision of higher-order multimodality is to improve diagnostics or guidance through the analysis of complementary, data-rich, co-registered images. Synergies achieved through combined modalities could enable researchers to better track diverse physiological and structural events, analyze biodistribution and treatment efficacy, and compare established and emerging modalities. Higher-order multimodal approaches stand to benefit from molecular imaging probes and, in recent years, contrast agents that have hypermodal characteristics have increasingly been reported in preclinical studies. Given the chemical requirements for contrast agents representing various modalities to be integrated into a single entity, the higher-order multimodal agents reported so far tend to be of nanoparticulate form. To date, the majority of reported nanoparticles have included components that are active for magnetic resonance. Herein, recent progress in higher-order multimodal imaging agents is reviewed, spanning a range of material and structural classes, and demonstrating utility in three (or more) imaging modalities.
Evaluation of expressions involving higher order derivations
NASA Technical Reports Server (NTRS)
Grossman, Robert
1990-01-01
The local geometric properties of a nonlinear control system defined by vector fields E(sub 1),..., E(sub M) are determined by the algebraic properties of the iterated Lie brackets of the E(sub j)'s. The problem of rewriting expressions is examined involving the E(sub j)'s in terms of the D(sub mu)'s in such a way as to handle effectively any cancellation occurring due to commuting of the D(sub mu)'s. A data structure is introduced which allows us to organize the computation to take advantage of the symmetries in the expression and reduce the operation count.
New, higher-order, elasticity-based micromechanics model
Williams, T. O.
2003-01-01
The formulation for a new homogenization theory is presented. The theory utilizes a higher-order, elasticity-based cell analysis of a periodic array of unit cells. The unit cell is discretized into subregions or subcells. The displacement field within each subcell is approximated by an (truncated) eigenfunction function expansion of up to fifth order. The governing equations are developed by satisfying the pointwise governing equations of geometrically linear continuum mechanics exactly up through the given order of the subcell displacement fields. The specified governing equations are valid for any type of constitutive model used to describe the behavior of the material in a subcell. The fifth order theory is subsequently reduced to a third order theory. The appropriate reduction of the fifth and third order theories to the first order theory (which corresponds to a variant of the original method of cells (MOC) (Aboudi, 1991) theory) is outlined. The 3D ECM theory correctly reduces to the 2D ECM theory microstructures and the exact 1D theory for bilaminated structures. Comparison of the predicted bulk and local responses with published results indicates that the theory accurately predicts both types of responses. Furthermore, it is shown that the higher order fields introduced coupling effects between the local fields that can result in substantial changes in the predicted bulk inelastic response of a composite.
Higher-order polarization singularitites in tailored vector beams
NASA Astrophysics Data System (ADS)
Otte, E.; Alpmann, C.; Denz, C.
2016-07-01
Higher-order polarization singularities embedded in tailored vector beams are introduced and experimentally realized. As holographic modulation allows to define order and location of any vectorial singularity, the surrounding vector field can be dynamically shaped. We demonstrate light fields associated with flowers or spider webs due to regular and even irregular patterns of the orientation of polarization ellipses. Beyond that, not yet investigated hybrid structures are introduced that allow generating networks of flowers and webs in very close vicinity. Our results pave the way to applications of singular optics in spatially extended, optimized optical tweezing and high-resolution imaging.
Skinner-Rusk unified formalism for higher-order systems
NASA Astrophysics Data System (ADS)
Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso
2012-07-01
The Lagrangian-Hamiltonian unified formalism of R. Skinner and R. Rusk was originally stated for autonomous dynamical systems in classical mechanics. It has been generalized for non-autonomous first-order mechanical systems, first-order and higher-order field theories, and higher-order autonomous systems. In this work we present a generalization of this formalism for higher-order non-autonomous mechanical systems.
Conceptualizing and Assessing Higher-Order Thinking in Reading
ERIC Educational Resources Information Center
Afflerbach, Peter; Cho, Byeong-Young; Kim, Jong-Yun
2015-01-01
Students engage in higher-order thinking as they read complex texts and perform complex reading-related tasks. However, the most consequential assessments, high-stakes tests, are currently limited in providing information about students' higher-order thinking. In this article, we describe higher-order thinking in relation to reading. We provide a…
Higher Order Mode Damping Simulation and Multipacting Analysis
NASA Astrophysics Data System (ADS)
Xiao, Liling
2015-10-01
When the beam is passing through an accelerator, it will generate higher order modes (HOM), which will affect to the beam quality especially in high energy accelerators such as International Linear accelerator Collider (ILC). In order to preserve the beam quality, HOM couplers are required to be installed to extract HOM power. Most of HOM couplers are 3D complex structures including small features. In addition, many physics process are involved in HOM coupler design such as RF heating and multipacting. Numerical modeling and simulation are essential for HOM coupler design and optimization for successful operation of high energy accelerators. SLAC developed 3D finite element parallel electromagnetics code suite ACE3P can be used to accelerator modeling with higher accuracy in fast turnaround time. In this paper, ACE3P application for HOM damping simulation and multipating analysis is presented for ILC 3.9 GHz crab cavity.
Higher order spin effects in inspiralling compact objects binaries
NASA Astrophysics Data System (ADS)
Marsat, Sylvain
2015-04-01
We present recent progress on higher order spin effects in the post-Newtonian dynamics of compact objects binaries. We present first an extension of a Lagrangian formalism for point particle with spins, where finite size effects are represented by an additional multipolar structure. When applied to the case of a spin-induced octupole, the formalism allows for the computation of the cubic-in-spin effects that enter at the order 3.5PN. We also report on results obtained for quadratic-in-spin effects at the next-to-leading order 3PN. In both cases, we recover existing results for the dynamics, and derive for the first time the gravitational wave energy flux and orbital phasing. These results will be useful for the data analysis of the upcoming generation of advanced detectors of gravitational waves. NASA Grant 11-ATP-046.
NASA Astrophysics Data System (ADS)
Tawfik, Abdel Nasser; Magdy, Niseem
2015-01-01
Effects of an external magnetic field on various properties of quantum chromodynamics (QCD) matter under extreme conditions of temperature and density (chemical potential) have been analyzed. To this end, we use SU(3) Polyakov linear-σ model and assume that the external magnetic field (e B ) adds some restrictions to the quarks' energy due to the existence of free charges in the plasma phase. In doing this, we apply the Landau theory of quantization, which assumes that the cyclotron orbits of charged particles in a magnetic field should be quantized. This requires an additional temperature to drive the system through the chiral phase transition. Accordingly, the dependence of the critical temperature of chiral and confinement phase transitions on the magnetic field is characterized. Based on this, we have studied the thermal evolution of thermodynamic quantities (energy density and trace anomaly) and the first four higher-order moment of particle multiplicity. Having all these calculations, we have studied the effects of the magnetic field on the chiral phase transition. We found that both critical temperature Tc and critical chemical potential increase with increasing magnetic field, e B . Last but not least, the magnetic effects of the thermal evolution of four scalar and four pseudoscalar meson states are studied. We concluded that the meson masses decrease as the temperature increases up to Tc. Then, the vacuum effect becomes dominant and rapidly increases with the temperature T . At low T , the scalar meson masses normalized to the lowest Matsubara frequency rapidly decrease as T increases. Then, starting from Tc, we find that the thermal dependence almost vanishes. Furthermore, the meson masses increase with increasing magnetic field. This gives a characteristic phase diagram of T vs external magnetic field e B . At high T , we find that the masses of almost all meson states become temperature independent. It is worthwhile to highlight that the various meson
The Meaning of Higher-Order Factors in Reflective-Measurement Models
ERIC Educational Resources Information Center
Eid, Michael; Koch, Tobias
2014-01-01
Higher-order factor analysis is a widely used approach for analyzing the structure of a multidimensional test. Whenever first-order factors are correlated researchers are tempted to apply a higher-order factor model. But is this reasonable? What do the higher-order factors measure? What is their meaning? Willoughby, Holochwost, Blanton, and Blair…
Higher-order Dirac solitons in binary waveguide arrays
Tran, Truong X.; Duong, Dũng C.
2015-10-15
We study optical analogues of higher-order Dirac solitons (HODSs) in binary waveguide arrays. Like higher-order solitons obtained from the well-known nonlinear Schrödinger equation governing the pulse propagation in an optical fiber, these HODSs have amplitude profiles which are numerically shown to be periodic over large propagation distances. At the same time, HODSs possess some unique features. Firstly, the period of a HODS depends on its order parameter. Secondly, the discrete nature in binary waveguide arrays imposes the upper limit on the order parameter of HODSs. Thirdly, the order parameter of HODSs can vary continuously in a certain range. - Highlights: • Higher-order Dirac solitons in nonlinear binary waveguide arrays are numerically demonstrated. • Amplitude profiles of higher-order Dirac solitons are periodic during propagation. • The period of higher-order Dirac solitons decreases when the soliton order increases.
ERIC Educational Resources Information Center
Douglass, John Aubrey
2009-01-01
In the United States, developing "human capital" for both economic and social benefit is an idea as old as the nation itself and led to the emergence of world's first mass higher education system. Now most other nations are racing to expand access to universities and colleges and to expand their role in society. Higher education is…
Nagasaki-Takeuchi, Nahoko; Miyano, Masashi; Maeshima, Masayoshi
2008-10-01
PCaP1, a hydrophilic cation-binding protein, is bound to the plasma membrane in Arabidopsis thaliana. We focused on the physicochemical properties of PCaP1 to understand its uniqueness in terms of structure and binding of metal ions. On fluorescence analysis, PCaP1 showed a signal of structural change in the presence of Cu(2+). The near-UV CD spectra showed a marked change of PCaP1 in CuCl(2) solution. The far-UV CD spectra showed the presence of alpha-helices and the intrinsically unstructured region. However, addition of Cu(2+) gave no change in the far-UV CD spectra. These results indicate that Cu(2+) induced a change in the tertiary structure without changing the secondary structure. The protein was sensitive to proteinase in the presence of Cu(2+), supporting that Cu(2+) is involved in the structural change. The PCaP1 solution was titrated with CuCl(2) and the change in the fluorescence spectrum was monitored to characterize Cu(2+)-binding properties. The obtained values of K(d) for Cu(2+) and the ligand-binding number were 10 microM and six ions per molecule, respectively. These findings indicate that PCaP1 has a high Cu(2+)-binding capacity with a relatively high affinity. PCaP1 lacks cysteine and histidine residues. A large number of glutamate residues may be involved in the Cu(2+) binding.
Salveson, Patrick J; Spencer, Ryan K; Nowick, James S
2016-04-06
Oligomeric assemblies of the protein α-synuclein are thought to cause neurodegeneration in Parkinson's disease and related synucleinopathies. Characterization of α-synuclein oligomers at high resolution is an outstanding challenge in the field of structural biology. The absence of high-resolution structures of oligomers formed by α-synuclein impedes understanding the synucleinopathies at the molecular level. This paper reports the X-ray crystallographic structure of oligomers formed by a peptide derived from residues 36-55 of α-synuclein. The peptide 1a adopts a β-hairpin structure, which assembles in a hierarchical fashion. Three β-hairpins assemble to form a triangular trimer. Three copies of the triangular trimer assemble to form a basket-shaped nonamer. Two nonamers pack to form an octadecamer. Molecular modeling suggests that full-length α-synuclein may also be able to assemble in this fashion. Circular dichroism spectroscopy demonstrates that peptide 1a interacts with anionic lipid bilayer membranes, like oligomers of full-length α-synuclein. LDH and MTT assays demonstrate that peptide 1a is toxic toward SH-SY5Y cells. Comparison of peptide 1a to homologues suggests that this toxicity results from nonspecific interactions with the cell membrane. The oligomers formed by peptide 1a are fundamentally different than the proposed models of the fibrils formed by α-synuclein and suggest that α-Syn36-55, rather than the NAC, may nucleate oligomer formation.
First and Higher Order Effects on Zero Order Radiative Transfer Model
NASA Astrophysics Data System (ADS)
Neelam, M.; Mohanty, B.
2014-12-01
Microwave radiative transfer model are valuable tool in understanding the complex land surface interactions. Past literature has largely focused on local sensitivity analysis for factor priotization and ignoring the interactions between the variables and uncertainties around them. Since land surface interactions are largely nonlinear, there always exist uncertainties, heterogeneities and interactions thus it is important to quantify them to draw accurate conclusions. In this effort, we used global sensitivity analysis to address the issues of variable uncertainty, higher order interactions, factor priotization and factor fixing for zero-order radiative transfer (ZRT) model. With the to-be-launched Soil Moisture Active Passive (SMAP) mission of NASA, it is very important to have a complete understanding of ZRT for soil moisture retrieval to direct future research and cal/val field campaigns. This is a first attempt to use GSA technique to quantify first order and higher order effects on brightness temperature from ZRT model. Our analyses reflect conditions observed during the growing agricultural season for corn and soybeans in two different regions in - Iowa, U.S.A and Winnipeg, Canada. We found that for corn fields in Iowa, there exist significant second order interactions between soil moisture, surface roughness parameters (RMS height and correlation length) and vegetation parameters (vegetation water content, structure and scattering albedo), whereas in Winnipeg, second order interactions are mainly due to soil moisture and vegetation parameters. But for soybean fields in both Iowa and Winnipeg, we found significant interactions only to exist between soil moisture and surface roughness parameters.
1990-11-01
pattern (4 = 00) for Sikta’s triangle with a 3A and a = 30’. 113 mN -- i3 S• Corner Diffration ] - -. Sikta’s First Order 1 0 Ŕ 60 90 120 150 a 0 (deg...30 60 90 120 150 to 0 (deg.) Figure 79: The E-plane pattern (= - 00) for Sikta’s triangle with a = 9A and a = 300. 115 ,’• q Corner Diffration ...Figure 125: Co-polarized RCS in the 4 = 75’ plane of a 2A square plate with a ., polarized fixed source at Oi 450, 0’ = 450. - Corner Diffration Mome. n
Promoting Higher Order Thinking Skills Using Inquiry-Based Learning
ERIC Educational Resources Information Center
Madhuri, G. V.; Kantamreddi, V. S. S. N; Prakash Goteti, L. N. S.
2012-01-01
Active learning pedagogies play an important role in enhancing higher order cognitive skills among the student community. In this work, a laboratory course for first year engineering chemistry is designed and executed using an inquiry-based learning pedagogical approach. The goal of this module is to promote higher order thinking skills in…
Chevrier, D; Vézina, C; Bastille, J; Linard, C; Sonenberg, N; Boileau, G
1988-01-15
The SP6 polymerase/promoter system was used to synthesize porcine pro-opiomelanocortin mRNAs with nucleotide sequence deletions in the 5'- as well as 3'-untranslated and coding regions. The translational efficiency of the mutant mRNAs was evaluated by cell-free translation or by monitoring the rate and extent of ribosome binding in the presence of sparsomycin. The results of these experiments indicate that specific nucleotide sequences in the 5'-untranslated and coding regions of the pro-opiomelanocortin mRNA decrease its rate of translation. Structure mapping of the mRNA with double-strand and single-strand specific nucleases suggests that these sequences can form stable secondary structures.
Higher-order theories from the minimal length
NASA Astrophysics Data System (ADS)
Dias, M.; Hoff da Silva, J. M.; Scatena, E.
2016-06-01
We show that the introduction of a minimal length in the context of noncommutative space-time gives rise (after some considerations) to higher-order theories. We then explicitly demonstrate how these higher-derivative theories appear as a generalization of the standard electromagnetism and general relativity by applying a consistent procedure that modifies the original Maxwell and Einstein-Hilbert actions. In order to set a bound on the minimal length, we compare the deviations from the inverse-square law with the potentials obtained in the higher-order theories and discuss the validity of the results. The introduction of a quantum bound for the minimal length parameter β in the higher-order QED allows us to lower the actual limits on the parameters of higher-derivative gravity by almost half of their order of magnitude.
Application of Mass Lumped Higher Order Finite Elements
Chen, J.; Strauss, H. R.; Jardin, S. C.; Park, W.; Sugiyama, L. E.; G. Fu; Breslau, J.
2005-11-01
There are many interesting phenomena in extended-MHD such as anisotropic transport, mhd, 2-fluid effects stellarator and hot particles. Any one of them challenges numerical analysts, and researchers are seeking for higher order methods, such as higher order finite difference, higher order finite elements and hp/spectral elements. It is true that these methods give more accurate solution than their linear counterparts. However, numerically they are prohibitively expensive. Here we give a successful solution of this conflict by applying mass lumped higher order finite elements. This type of elements not only keep second/third order accuracy but also scale closely to linear elements by doing mass lumping. This is especially true for second order lump elements. Full M3D and anisotropic transport models are studied.
J Adams; M Currie; S Ali; E Bayer; Z Jia; S Smith
2011-12-31
Cellulosomes are large, multienzyme, plant cell wall-degrading protein complexes found affixed to the surface of a variety of anaerobic microbes. The core of the cellulosome is a noncatalytic scaffoldin protein, which contains several type-I cohesin modules that bind type-I dockerin-containing enzymatic subunits, a cellulose-binding module, an X module, and a type-II dockerin that interacts with type-II cohesin-containing cell surface proteins. The unique arrangement of the enzymatic subunits in the cellulosome complex, made possible by the scaffoldin subunit, promotes enhanced substrate degradation relative to the enzymes free in solution. Despite representative high-resolution structures of all of the individual modules of the cellulosome, this mechanism of enzymatic synergy remains poorly understood. Consequently, a model of the entire cellulosome and a detailed picture of intermodular contacts will provide more detailed insight into cellulosome activity. Toward this goal, we have solved the structure of a multimodular heterodimeric complex from Clostridium thermocellum composed of the type-II cohesin module of the cell surface protein SdbA bound to a trimodular C-terminal fragment of the scaffoldin subunit CipA to a resolution of 1.95 {angstrom}. The linker that connects the ninth type-I cohesin module and the X module has elevated temperature factors, reflecting an inherent flexibility within this region. Interestingly, a novel dimer interface was observed between CipA and a second, symmetry-related CipA molecule within the crystal structure, mediated by contacts between a type-I cohesin and an X module of a symmetry mate, resulting in two intertwined scaffoldins. Sedimentation velocity experiments confirmed that dimerization also occurs in solution. These observations support the intriguing possibility that individual cellulosomes can associate with one another via inter-scaffoldin interactions, which may play a role in the mechanism of action of the complex.
Giusti, Chad; Ghrist, Robert; Bassett, Danielle S
2016-08-01
The language of graph theory, or network science, has proven to be an exceptional tool for addressing myriad problems in neuroscience. Yet, the use of networks is predicated on a critical simplifying assumption: that the quintessential unit of interest in a brain is a dyad - two nodes (neurons or brain regions) connected by an edge. While rarely mentioned, this fundamental assumption inherently limits the types of neural structure and function that graphs can be used to model. Here, we describe a generalization of graphs that overcomes these limitations, thereby offering a broad range of new possibilities in terms of modeling and measuring neural phenomena. Specifically, we explore the use of simplicial complexes: a structure developed in the field of mathematics known as algebraic topology, of increasing applicability to real data due to a rapidly growing computational toolset. We review the underlying mathematical formalism as well as the budding literature applying simplicial complexes to neural data, from electrophysiological recordings in animal models to hemodynamic fluctuations in humans. Based on the exceptional flexibility of the tools and recent ground-breaking insights into neural function, we posit that this framework has the potential to eclipse graph theory in unraveling the fundamental mysteries of cognition.
Non-rigid registration using higher-order mutual information
NASA Astrophysics Data System (ADS)
Rueckert, D.; Clarkson, M. J.; Hill, D. L. G.; Hawkes, D. J.
2000-03-01
Non-rigid registration of multi-modality images is an important tool for assessing temporal and structural changesbetween images. For rigid registration, voxel similarity measures like mutual information have been shown to alignimages from different modalities accurately and robustly. For non-rigid registration, mutual information can besensitive to local variations of intensity which in MR images may be caused by RF inhomogeneity. The reasonfor the sensitivity of mutual information towards intensity variations stems from the fact that mutual informationignores any spatial information. In this paper we propose an extension of the mutual information framework whichincorporates spatial information about higher-order image structure into the registration process and has the potentialto improve the accuracy and robustness of non-rigid registration in the presence of intensity variations. We haveapplied the non-rigid registration algorithm to a number of simulated MR brain images of a digital phantom whichhave been degraded by a simulated intensity shading and a known deformation. In addition, we have applied thealgorithm for the non-rigid registration of eight pre- and post-operative brain MR images which were acquired withan interventional MR scanner and therefore have substantial intensity shading due to RF field inhomogeneities. Inall cases the second-order estimate of mutual information leads to robust and accurate registration.
Dynamic facilitation picture of a higher-order glass singularity.
Sellitto, Mauro; De Martino, Daniele; Caccioli, Fabio; Arenzon, Jeferson J
2010-12-31
We show that facilitated spin mixtures with a tunable facilitation reproduce, on a Bethe lattice, the simplest higher-order singularity scenario predicted by the mode-coupling theory (MCT) of liquid-glass transition. Depending on the facilitation strength, they yield either a discontinuous glass transition or a continuous one, with no underlying thermodynamic singularity. Similar results are obtained for facilitated spin models on a diluted Bethe lattice. The mechanism of dynamical arrest in these systems can be interpreted in terms of bootstrap and standard percolation and corresponds to a crossover from a compact to a fractal structure of the incipient spanning cluster of frozen spins. Theoretical and numerical simulation results are fully consistent with MCT predictions.
RNA Seeds Higher Order Assembly of FUS Protein
Schwartz, Jacob C.; Wang, Xueyin; Podell, Elaine R.; Cech, Thomas R.
2014-01-01
SUMMARY The abundant nuclear RNA-binding protein FUS binds the CTD of RNA polymerase II in an RNA-dependent manner, affecting Ser2 phosphorylation and transcription. Here we examine the mechanism of this process and find that RNA binding nucleates the formation of higher order FUS RNP assemblies that bind the CTD. Both the low-complexity domain and the RGG domain of FUS contribute to assembly. The assemblies appear fibrous by electron microscopy and have characteristics of beta-zipper structures. These results support the emerging view that the pathologic protein aggregation seen in neurodegenerative diseases such as ALS may occur by exaggeration of functionally important assemblies of RNA-binding proteins. PMID:24268778
Higher-order intersections in low-dimensional topology
Conant, Jim; Schneiderman, Rob; Teichner, Peter
2011-01-01
We show how to measure the failure of the Whitney move in dimension 4 by constructing higher-order intersection invariants of Whitney towers built from iterated Whitney disks on immersed surfaces in 4-manifolds. For Whitney towers on immersed disks in the 4-ball, we identify some of these new invariants with previously known link invariants such as Milnor, Sato–Levine, and Arf invariants. We also define higher-order Sato–Levine and Arf invariants and show that these invariants detect the obstructions to framing a twisted Whitney tower. Together with Milnor invariants, these higher-order invariants are shown to classify the existence of (twisted) Whitney towers of increasing order in the 4-ball. A conjecture regarding the nontriviality of the higher-order Arf invariants is formulated, and related implications for filtrations of string links and 3-dimensional homology cylinders are described. PMID:21518909
NASA Astrophysics Data System (ADS)
Bednar, Jan; Horowitz, Rachel A.; Grigoryev, Sergei A.; Carruthers, Lenny M.; Hansen, Jeffrey C.; Koster, Abraham J.; Woodcock, Christopher L.
1998-11-01
The compaction level of arrays of nucleosomes may be understood in terms of the balance between the self-repulsion of DNA (principally linker DNA) and countering factors including the ionic strength and composition of the medium, the highly basic N termini of the core histones, and linker histones. However, the structural principles that come into play during the transition from a loose chain of nucleosomes to a compact 30-nm chromatin fiber have been difficult to establish, and the arrangement of nucleosomes and linker DNA in condensed chromatin fibers has never been fully resolved. Based on images of the solution conformation of native chromatin and fully defined chromatin arrays obtained by electron cryomicroscopy, we report a linker histone-dependent architectural motif beyond the level of the nucleosome core particle that takes the form of a stem-like organization of the entering and exiting linker DNA segments. DNA completes ≈ 1.7 turns on the histone octamer in the presence and absence of linker histone. When linker histone is present, the two linker DNA segments become juxtaposed ≈ 8 nm from the nucleosome center and remain apposed for 3-5 nm before diverging. We propose that this stem motif directs the arrangement of nucleosomes and linker DNA within the chromatin fiber, establishing a unique three-dimensional zigzag folding pattern that is conserved during compaction. Such an arrangement with peripherally arranged nucleosomes and internal linker DNA segments is fully consistent with observations in intact nuclei and also allows dramatic changes in compaction level to occur without a concomitant change in topology.
Higher-order phase transitions on financial markets
NASA Astrophysics Data System (ADS)
Kasprzak, A.; Kutner, R.; Perelló, J.; Masoliver, J.
2010-08-01
Statistical and thermodynamic properties of the anomalous multifractal structure of random interevent (or intertransaction) times were thoroughly studied by using the extended continuous-time random walk (CTRW) formalism of Montroll, Weiss, Scher, and Lax. Although this formalism is quite general (and can be applied to any interhuman communication with nontrivial priority), we consider it in the context of a financial market where heterogeneous agent activities can occur within a wide spectrum of time scales. As the main general consequence, we found (by additionally using the Saddle-Point Approximation) the scaling or power-dependent form of the partition function, Z(q'). It diverges for any negative scaling powers q' (which justifies the name anomalous) while for positive ones it shows the scaling with the general exponent τ(q'). This exponent is the nonanalytic (singular) or noninteger power of q', which is one of the pilar of higher-order phase transitions. In definition of the partition function we used the pausing-time distribution (PTD) as the central one, which takes the form of convolution (or superstatistics used, e.g. for describing turbulence as well as the financial market). Its integral kernel is given by the stretched exponential distribution (often used in disordered systems). This kernel extends both the exponential distribution assumed in the original version of the CTRW formalism (for description of the transient photocurrent measured in amorphous glassy material) as well as the Gaussian one sometimes used in this context (e.g. for diffusion of hydrogen in amorphous metals or for aging effects in glasses). Our most important finding is the third- and higher-order phase transitions, which can be roughly interpreted as transitions between the phase where high frequency trading is most visible and the phase defined by low frequency trading. The specific order of the phase transition directly depends upon the shape exponent α defining the stretched
On the Higher Power Sums of Reciprocal Higher-Order Sequences
Zhang, Jin
2014-01-01
Let {un} be a higher-order linear recursive sequence. In this paper, we use the properties of error estimation and the analytic method to study the reciprocal sums of higher power of higher-order sequences. Then we establish several new and interesting identities relating to the infinite and finite sums. PMID:24741351
Unambiguous formalism for higher order Lagrangian field theories
NASA Astrophysics Data System (ADS)
Campos, Cédric M.; de León, Manuel; Martín de Diego, David; Vankerschaver, Joris
2009-11-01
The aim of this paper is to propose an unambiguous intrinsic formalism for higher order field theories which avoids the arbitrariness in the generalization of the conventional description of field theories, and implies the existence of different Cartan forms and Legendre transformations. We propose a differential-geometric setting for the dynamics of a higher order field theory, based on the Skinner and Rusk formalism for mechanics. This approach incorporates aspects of both the Lagrangian and the Hamiltonian description, since the field equations are formulated using the Lagrangian on a higher order jet bundle and the canonical multisymplectic form on its affine dual. As both of these objects are uniquely defined, the Skinner-Rusk approach has the advantage that it does not suffer from the arbitrariness in conventional descriptions. The result is that we obtain a unique and global intrinsic version of the Euler-Lagrange equations for higher order field theories. Several examples illustrate our construction.
Higher Order Lagrange Finite Elements In M3D
J. Chen; H.R. Strauss; S.C. Jardin; W. Park; L.E. Sugiyama; G. Fu; J. Breslau
2004-12-17
The M3D code has been using linear finite elements to represent multilevel MHD on 2-D poloidal planes. Triangular higher order elements, up to third order, are constructed here in order to provide M3D the capability to solve highly anisotropic transport problems. It is found that higher order elements are essential to resolve the thin transition layer characteristic of the anisotropic transport equation, particularly when the strong anisotropic direction is not aligned with one of the Cartesian coordinates. The transition layer is measured by the profile width, which is zero for infinite anisotropy. It is shown that only higher order schemes have the ability to make this layer converge towards zero when the anisotropy gets stronger and stronger. Two cases are considered. One has the strong transport direction partially aligned with one of the element edges, the other doesn't have any alignment. Both cases have the strong transport direction misaligned with the grid line by some angles.
The Lagrangian-Hamiltonian formalism for higher order field theories
NASA Astrophysics Data System (ADS)
Vitagliano, Luca
2010-06-01
We generalize the Lagrangian-Hamiltonian formalism of Skinner and Rusk to higher order field theories on fiber bundles. As a byproduct we solve the long standing problem of defining, in a coordinate free manner, a Hamiltonian formalism for higher order Lagrangian field theories. Namely, our formalism does only depend on the action functional and, therefore, unlike previously proposed ones, is free from any relevant ambiguity.
Next-order structure-function equations
NASA Astrophysics Data System (ADS)
Hill, Reginald J.; Boratav, Olus N.
2001-01-01
Kolmogorov's equation [Dokl. Akad. Nauk SSSR 32, 16 (1941)] relates the two-point second- and third-order velocity structure functions and the energy dissipation rate. The analogous next higher-order two-point equation relates the third- and fourth-order velocity structure functions and the structure function of the product of pressure-gradient difference and two factors of velocity difference, denoted Tijk. The equation is simplified on the basis of local isotropy. Laboratory and numerical simulation data are used to evaluate and compare terms in the equation, examine the balance of the equation, and evaluate components of Tijk. Atmospheric surface-layer data are used to evaluate Tijk in the inertial range. Combined with the random sweeping hypothesis, the equation relates components of the fourth-order velocity structure function. Data show the resultant error of this application of random sweeping. The next-order equation constrains the relationships that have been suggested among components of the fourth-order velocity structure function. The pressure structure function, pressure-gradient correlation, and mean-squared pressure gradient are related to Tijk. Inertial range formulas are discussed.
Determination of higher order accelerations by a functional method
NASA Astrophysics Data System (ADS)
Tudosie, C.
A functional method is developed for the simultaneous determination of all the linear accelerations which exist in the differential equation of a material system dynamics. The method introduces variable angular accelerations of different orders, called direct connection functions, which allow the passing from a linear acceleration of a certain order to that of a higher order. Feedback functions are also introduced which allow the passing from a linear acceleration of a certain order to that of lower orders. This method is applicable to accelerations which occur when passenger trains move rapidly around a curve and at the vertical vibrations of trucks and tractors.
Higher-order graph wavelets and sparsity on circulant graphs
NASA Astrophysics Data System (ADS)
Kotzagiannidis, Madeleine S.; Dragotti, Pier Luigi
2015-08-01
The notion of a graph wavelet gives rise to more advanced processing of data on graphs due to its ability to operate in a localized manner, across newly arising data-dependency structures, with respect to the graph signal and underlying graph structure, thereby taking into consideration the inherent geometry of the data. In this work, we tackle the problem of creating graph wavelet filterbanks on circulant graphs for a sparse representation of certain classes of graph signals. The underlying graph can hereby be data-driven as well as fixed, for applications including image processing and social network theory, whereby clusters can be modelled as circulant graphs, respectively. We present a set of novel graph wavelet filter-bank constructions, which annihilate higher-order polynomial graph signals (up to a border effect) defined on the vertices of undirected, circulant graphs, and are localised in the vertex domain. We give preliminary results on their performance for non-linear graph signal approximation and denoising. Furthermore, we provide extensions to our previously developed segmentation-inspired graph wavelet framework for non-linear image approximation, by incorporating notions of smoothness and vanishing moments, which further improve performance compared to traditional methods.
Higher order relativistic galaxy number counts: dominating terms
NASA Astrophysics Data System (ADS)
TrØst Nielsen, Jeppe; Durrer, Ruth
2017-03-01
We review the number counts to second order concentrating on the terms which dominate on sub horizon scales. We re-derive the result for these terms and compare it with the different versions found in the literature. We generalize our derivation to higher order terms, especially the third order number counts which are needed to compute the 1-loop contribution to the power spectrum.
Higher-order figure discrimination in fly and human vision.
Aptekar, Jacob W; Frye, Mark A
2013-08-19
Visually-guided animals rely on their ability to stabilize the panorama and simultaneously track salient objects, or figures, that are distinct from the background in order to avoid predators, pursue food resources and mates, and navigate spatially. Visual figures are distinguished by luminance signals that produce coherent motion cues as well as more enigmatic 'higher-order' statistical features. Figure discrimination is thus a complex form of motion vision requiring specialized neural processing. In this minireview, we will highlight recent advances in understanding the perceptual, behavioral, and neurophysiological basis of higher-order figure detection in flies, much of which is grounded in the historical perspective and mechanistic underpinnings of human psychophysics.
Higher order annular Gaussian laser beam propagation in free space
NASA Astrophysics Data System (ADS)
Eyyuboglu, Halil T.; Yenice, Yusuf E.; Baykal, Yahya K.
2006-03-01
Propagation of higher order annular Gaussian (HOAG) laser beams in free space is examined. HOAG beams are defined as the difference of two Hermite-Gaussian (HG) beams; thus, they can be produced by subtracting a smaller beam from a larger beam, that are cocentered and both possess HG mode field distributions. Such beams can be considered as a generalization of the well-known annular Gaussian beams. We formulate the source and receiver plane characteristics and kurtosis parameter of HOAG beams propagating in free space and evaluate them numerically. In comparison to HG beams, HOAG beams have a broader beam size with outer lobes of kidney shape. The amount of received power within the same receiver aperture size, that is, power in bucket, is generally lower for higher order beams. The convergence of the kurtosis parameter to an asymptotic value for higher order beams takes much longer propagation distances compared to zero-order beams.
Tran, Ulrich S.; Cebolla, Ausiàs; Glück, Tobias M.; Soler, Joaquim; Garcia-Campayo, Javier; von Moy, Theresa
2014-01-01
Objective To investigate the psychometric and structural properties of the Five Facets Mindfulness Questionnaire (FFMQ) among meditators, to develop a short form, and to examine associations of mindfulness with mental health and the mechanisms of mindfulness. Methods Two independent samples were used, a German (n = 891) and a Spanish (n = 393) meditator sample, practicing various meditation styles. Structural and psychometric properties of the FFMQ were investigated with multigroup confirmatory factor analysis and exploratory structural equation modeling. Associations with mental health and mechanisms of mindfulness were examined with path analysis. Results The derived short form broadly matched a previous item selection in samples of non-meditators. Self-regulated Attention and Orientation to Experience governed the facets of mindfulness on a higher-order level. Higher-order factors of mindfulness and meditation experience were negatively associated with symptoms of depression and anxiety, and perceived stress. Decentering and nonattachment were the most salient mechanisms of mindfulness. Aspects of emotion regulation, bodily awareness, and nonattachment explained the effects of mindfulness on depression and anxiety. Conclusions A two-component conceptualization for the FFMQ, and for the study of mindfulness as a psychological construct, is recommended for future research. Mechanisms of mindfulness need to be examined in intervention studies. PMID:25330072
Dynamics and control of higher-order nonholonomic systems
NASA Astrophysics Data System (ADS)
Rubio Hervas, Jaime
A theoretical framework is established for the control of higher-order nonholonomic systems, defined as systems that satisfy higher-order nonintegrable constraints. A model for such systems is developed in terms of differential-algebraic equations defined on a higher-order tangent bundle. A number of control-theoretic properties such as nonintegrability, controllability, and stabilizability are presented. Higher-order nonholonomic systems are shown to be strongly accessible and, under certain conditions, small time locally controllable at any equilibrium. There are important examples of higher-order nonholonomic systems that are asymptotically stabilizable via smooth feedback, including space vehicles with multiple slosh modes and Prismatic-Prismatic-Revolute (PPR) robots moving open liquid containers, as well as an interesting class of systems that do not admit asymptotically stabilizing continuous static or dynamic state feedback. Specific assumptions are introduced to define this class, which includes important examples of robotic systems. A discontinuous nonlinear feedback control algorithm is developed to steer any initial state to the equilibrium at the origin. The applicability of the theoretical development is illustrated through two examples: control of a planar PPR robot manipulator subject to a jerk constraint and control of a point mass moving on a constant torsion curve in a three dimensional space.
Higher-order discrete variational problems with constraints
NASA Astrophysics Data System (ADS)
Colombo, Leonardo; Martín de Diego, David; Zuccalli, Marcela
2013-09-01
An interesting family of geometric integrators for Lagrangian systems can be defined using discretizations of the Hamilton's principle of critical action. This family of geometric integrators is called variational integrators. In this paper, we derive new variational integrators for higher-order Lagrangian mechanical system subjected to higher-order constraints. From the discretization of the variational principles, we show that our methods are automatically symplectic and, in consequence, with a very good energy behavior. Additionally, the symmetries of the discrete Lagrangian imply that momentum is conserved by the integrator. Moreover, we extend our construction to variational integrators where the Lagrangian is explicitly time-dependent. Finally, some motivating applications of higher-order problems are considered; in particular, optimal control problems for explicitly time-dependent underactuated systems and an interpolation problem on Riemannian manifolds.
Higher-order modulation instability in nonlinear fiber optics.
Erkintalo, Miro; Hammani, Kamal; Kibler, Bertrand; Finot, Christophe; Akhmediev, Nail; Dudley, John M; Genty, Goëry
2011-12-16
We report theoretical, numerical, and experimental studies of higher-order modulation instability in the focusing nonlinear Schrödinger equation. This higher-order instability arises from the nonlinear superposition of elementary instabilities, associated with initial single breather evolution followed by a regime of complex, yet deterministic, pulse splitting. We analytically describe the process using the Darboux transformation and compare with experiments in optical fiber. We show how a suitably low frequency modulation on a continuous wave field induces higher-order modulation instability splitting with the pulse characteristics at different phases of evolution related by a simple scaling relationship. We anticipate that similar processes are likely to be observed in many other systems including plasmas, Bose-Einstein condensates, and deep water waves.
A general higher-order remap algorithm for ALE calculations
Chiravalle, Vincent P
2011-01-05
A numerical technique for solving the equations of fluid dynamics with arbitrary mesh motion is presented. The three phases of the Arbitrary Lagrangian Eulerian (ALE) methodology are outlined: the Lagrangian phase, grid relaxation phase and remap phase. The Lagrangian phase follows a well known approach from the HEMP code; in addition the strain rate andflow divergence are calculated in a consistent manner according to Margolin. A donor cell method from the SALE code forms the basis of the remap step, but unlike SALE a higher order correction based on monotone gradients is also added to the remap. Four test problems were explored to evaluate the fidelity of these numerical techniques, as implemented in a simple test code, written in the C programming language, called Cercion. Novel cell-centered data structures are used in Cercion to reduce the complexity of the programming and maximize the efficiency of memory usage. The locations of the shock and contact discontinuity in the Riemann shock tube problem are well captured. Cercion demonstrates a high degree of symmetry when calculating the Sedov blast wave solution, with a peak density at the shock front that is similar to the value determined by the RAGE code. For a flyer plate test problem both Cercion and FLAG give virtually the same velocity temporal profile at the target-vacuum interface. When calculating a cylindrical implosion of a steel shell, Cercion and FLAG agree well and the Cercion results are insensitive to the use of ALE.
Higher-order web link analysis using multilinear algebra.
Kenny, Joseph P.; Bader, Brett William; Kolda, Tamara Gibson
2005-07-01
Linear algebra is a powerful and proven tool in web search. Techniques, such as the PageRank algorithm of Brin and Page and the HITS algorithm of Kleinberg, score web pages based on the principal eigenvector (or singular vector) of a particular non-negative matrix that captures the hyperlink structure of the web graph. We propose and test a new methodology that uses multilinear algebra to elicit more information from a higher-order representation of the hyperlink graph. We start by labeling the edges in our graph with the anchor text of the hyperlinks so that the associated linear algebra representation is a sparse, three-way tensor. The first two dimensions of the tensor represent the web pages while the third dimension adds the anchor text. We then use the rank-1 factors of a multilinear PARAFAC tensor decomposition, which are akin to singular vectors of the SVD, to automatically identify topics in the collection along with the associated authoritative web pages.
Higher-Order Synaptic Interactions Coordinate Dynamics in Recurrent Networks
Chambers, Brendan; MacLean, Jason N.
2016-01-01
Linking synaptic connectivity to dynamics is key to understanding information processing in neocortex. Circuit dynamics emerge from complex interactions of interconnected neurons, necessitating that links between connectivity and dynamics be evaluated at the network level. Here we map propagating activity in large neuronal ensembles from mouse neocortex and compare it to a recurrent network model, where connectivity can be precisely measured and manipulated. We find that a dynamical feature dominates statistical descriptions of propagating activity for both neocortex and the model: convergent clusters comprised of fan-in triangle motifs, where two input neurons are themselves connected. Fan-in triangles coordinate the timing of presynaptic inputs during ongoing activity to effectively generate postsynaptic spiking. As a result, paradoxically, fan-in triangles dominate the statistics of spike propagation even in randomly connected recurrent networks. Interplay between higher-order synaptic connectivity and the integrative properties of neurons constrains the structure of network dynamics and shapes the routing of information in neocortex. PMID:27542093
Higher order statistical frequency domain decomposition for operational modal analysis
NASA Astrophysics Data System (ADS)
Nita, G. M.; Mahgoub, M. A.; Sharyatpanahi, S. G.; Cretu, N. C.; El-Fouly, T. M.
2017-02-01
Experimental methods based on modal analysis under ambient vibrational excitation are often employed to detect structural damages of mechanical systems. Many of such frequency domain methods, such as Basic Frequency Domain (BFD), Frequency Domain Decomposition (FFD), or Enhanced Frequency Domain Decomposition (EFFD), use as first step a Fast Fourier Transform (FFT) estimate of the power spectral density (PSD) associated with the response of the system. In this study it is shown that higher order statistical estimators such as Spectral Kurtosis (SK) and Sample to Model Ratio (SMR) may be successfully employed not only to more reliably discriminate the response of the system against the ambient noise fluctuations, but also to better identify and separate contributions from closely spaced individual modes. It is shown that a SMR-based Maximum Likelihood curve fitting algorithm may improve the accuracy of the spectral shape and location of the individual modes and, when combined with the SK analysis, it provides efficient means to categorize such individual spectral components according to their temporal dynamics as coherent or incoherent system responses to unknown ambient excitations.
Generation of Higher Order Modes in a Rectangular Duct
NASA Technical Reports Server (NTRS)
Gerhold, Carl H.; Cabell, Randolph H.; Brown, Donald E.
2004-01-01
Advanced noise control methodologies to reduce sound emission from aircraft engines take advantage of the modal structure of the noise in the duct. This noise is caused by the interaction of rotor wakes with downstream obstructions such as exit guide vanes. Mode synthesis has been accomplished in circular ducts and current active noise control work has made use of this capability to cancel fan noise. The goal of the current effort is to examine the fundamental process of higher order mode propagation through an acoustically treated, curved duct. The duct cross-section is rectangular to permit greater flexibility in representation of a range of duct curvatures. The work presented is the development of a feedforward control system to generate a user-specified modal pattern in the duct. The multiple-error, filtered-x LMS algorithm is used to determine the magnitude and phase of signal input to the loudspeakers to produce a desired modal pattern at a set of error microphones. Implementation issues, including loudspeaker placement and error microphone placement, are discussed. Preliminary results from a 9-3/8 inch by 21 inch duct, using 12 loudspeakers and 24 microphones, are presented. These results demonstrate the ability of the control system to generate a user-specified mode while suppressing undesired modes.
Detection of small target using recursive higher order statistics
NASA Astrophysics Data System (ADS)
Hou, Wang; Sun, Hongyuan; Lei, Zhihui
2014-02-01
In this paper, a recursive higher order statistics algorithm is proposed for small target detection in temporal domain. Firstly, the background of image sequence is normalized. Then, the higher order statistics are recursively solved in image sequence to obtain the feature image. Finally, the feature image is segmented with threshold to detect the small target. To validate the algorithm proposed in this paper, five simulated and one semi-simulation image sequences are created. The ROC curves are employed for evaluation of experimental results. Experiment results show that our method is very effective for small target detection.
Vakonomic Constraints in Higher-Order Classical Field Theory
NASA Astrophysics Data System (ADS)
Campos, Cédric M.
2010-07-01
We propose a differential-geometric setting for the dynamics of a higher-order field theory, based on the Skinner and Rusk formalism for mechanics. This approach incorporates aspects of both, the Lagrangian and the Hamiltonian description, since the field equations are formulated using the Lagrangian on a higher-order jet bundle and the canonical multisymplectic form on its affine dual. The result is that we obtain a unique and global intrinsic description of the dynamics. The case of vakonomic constraints is also studied within this formalism.
Higher-Order Airy Scaling in Deformed Dyck Paths
NASA Astrophysics Data System (ADS)
Haug, Nils; Olde Daalhuis, Adri; Prellberg, Thomas
2017-03-01
We introduce a deformed version of Dyck paths (DDP), where additional to the steps allowed for Dyck paths, `jumps' orthogonal to the preferred direction of the path are permitted. We consider the generating function of DDP, weighted with respect to their half-length, area and number of jumps. This represents the first example of an exactly solvable two-dimensional lattice vesicle model showing a higher-order multicritical point. Applying the generalized method of steepest descents, we see that the associated two-variable scaling function is given by the logarithmic derivative of a generalized (higher-order) Airy integral.
Numerical modeling of higher order magnetic moments in UXO discrimination
Sanchez, V.; Yaoguo, L.; Nabighian, M.N.; Wright, D.L.
2008-01-01
The surface magnetic anomaly observed in unexploded ordnance (UXO) clearance is mainly dipolar, and consequently, the dipole is the only magnetic moment regularly recovered in UXO discrimination. The dipole moment contains information about the intensity of magnetization but lacks information about the shape of the target. In contrast, higher order moments, such as quadrupole and octupole, encode asymmetry properties of the magnetization distribution within the buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and to show its potential utility in UXO clearance, we present a numerical modeling study of UXO and related metallic objects. The tool for the modeling is a nonlinear integral equation describing magnetization within isolated compact objects of high susceptibility. A solution for magnetization distribution then allows us to compute the magnetic multipole moments of the object, analyze their relationships, and provide a depiction of the anomaly produced by different moments within the object. Our modeling results show the presence of significant higher order moments for more asymmetric objects, and the fields of these higher order moments are well above the noise level of magnetic gradient data. The contribution from higher order moments may provide a practical tool for improved UXO discrimination. ?? 2008 IEEE.
Higher Order Mode Coupler Heating in Continuous Wave Operation
NASA Astrophysics Data System (ADS)
Solyak, N.; Awida, M.; Hocker, A.; Khabibobulline, T.; Lunin, A.
Electromagnetic heating due to higher order modes (HOM) propagation is particularly a concern for continuous wave (CW) particle accelerator machines. Power on the order of several watts could flow out of the cavity's HOM ports in CW operations. The upgrade of the Linac Coherent Light Source (LCLS-II) at SLAC requires a major modification of the design of the higher order mode (HOM) antenna and feed through of the conventional ILC elliptical 9-cell cavity in order to utilize it for LCLS-II. The HOM antenna is required to bear higher RF losses, while relatively maintaining the coupling level of the higher order modes. In this paper, we present a detailed analysis of the heating expected in the HOM coupler with a thorough thermal quench study in comparison with the conventional ILC design. We discuss also how the heat will be removed from the cavity through RF cables with specially designed cooling straps. Finally, we report on the latest experimental results of cavity testing in vertical and horizontal cryostats.
Higher order matrix differential equations with singular coefficient matrices
Fragkoulis, V. C.; Kougioumtzoglou, I. A.; Pantelous, A. A.; Pirrotta, A.
2015-03-10
In this article, the class of higher order linear matrix differential equations with constant coefficient matrices and stochastic process terms is studied. The coefficient of the highest order is considered to be singular; thus, rendering the response determination of such systems in a straightforward manner a difficult task. In this regard, the notion of the generalized inverse of a singular matrix is used for determining response statistics. Further, an application relevant to engineering dynamics problems is included.
Prominent Higher-Order Contributions to Electronic Recombination
Beilmann, C.; Mokler, P. H.; Bernitt, S.; Keitel, C. H.; Ullrich, J.; Lopez-Urrutia, J. R. Crespo; Harman, Z.
2011-09-30
Intershell higher-order (HO) electronic recombination is reported for highly charged Ar, Fe, and Kr ions, where simultaneous excitation of one K-shell electron and one or two additional L-shell electrons occurs upon resonant capture of a free electron. For the mid-Z region, HO resonance strengths grow unexpectedly strong with decreasing atomic number Z ({proportional_to}Z{sup -4}), such that, for Ar ions the 2nd-order overwhelms the 1st-order resonant recombination considerably. The experimental findings are confirmed by multiconfiguration Dirac-Fock calculations including hitherto neglected excitation pathways.
Higher-order dynamical effects in Coulomb dissociation
Esbensen, H.; Bertsch, G.F.; Bertulani, C.A.
1995-08-01
Coulomb dissociation is a technique commonly used to extract the dipole response of nuclei far from stability. This technique is applicable if the dissociation is dominated by dipole transitions and if first-order perturbation theory is valid. In order to assess the significance of higher-order processes we solve numerically the time evolution of the wave function for a two-body breakup in the Coulomb field from a high Z target. We applied this method to the breakup reactions: {sup 11}Be {yields} {sup 10}Be + n and {sup 11}Li {yields} +2n. The latter is treated as a two-body breakup, using a di-neutron model.
Higher order microfibre modes for dielectric particle trapping and propulsion.
Maimaiti, Aili; Truong, Viet Giang; Sergides, Marios; Gusachenko, Ivan; Nic Chormaic, Síle
2015-03-13
Optical manipulation in the vicinity of optical micro- and nanofibres has shown potential across several fields in recent years, including microparticle control, and cold atom probing and trapping. To date, most work has focussed on the propagation of the fundamental mode through the fibre. However, along the maximum mode intensity axis, higher order modes have a longer evanescent field extension and larger field amplitude at the fibre waist compared to the fundamental mode, opening up new possibilities for optical manipulation and particle trapping. We demonstrate a microfibre/optical tweezers compact system for trapping and propelling dielectric particles based on the excitation of the first group of higher order modes at the fibre waist. Speed enhancement of polystyrene particle propulsion was observed for the higher order modes compared to the fundamental mode for particles ranging from 1 μm to 5 μm in diameter. The optical propelling velocity of a single, 3 μm polystyrene particle was found to be 8 times faster under the higher order mode than the fundamental mode field for a waist power of 25 mW. Experimental data are supported by theoretical calculations. This work can be extended to trapping and manipulation of laser-cooled atoms with potential for quantum networks.
Higher Order Language Competence and Adolescent Mental Health
ERIC Educational Resources Information Center
Cohen, Nancy J.; Farnia, Fataneh; Im-Bolter, Nancie
2013-01-01
Background: Clinic and community-based epidemiological studies have shown an association between child psychopathology and language impairment. The demands on language for social and academic adjustment shift dramatically during adolescence and the ability to understand the nonliteral meaning in language represented by higher order language…
Improving Reading Comprehension through Higher-Order Thinking Skills
ERIC Educational Resources Information Center
McKown, Brigitte A.; Barnett, Cynthia L.
2007-01-01
This action research project report documents the action research project that was conducted to improve reading comprehension with second grade and third grade students. The teacher researchers intended to improve reading comprehension by using higher-order thinking skills such as predicting, making connections, visualizing, inferring,…
Multimedia: A Gateway to Higher-Order Thinking Skills.
ERIC Educational Resources Information Center
Fontana, Lynn A.; And Others
In June 1990, the research group at George Mason University (Virginia) Center for Interactive Educational Technology began designing a multimedia prototype to foster higher-order thinking skills in social studies. As an initial step, the Civil War Interactive Project using the Ken Burns documentary, "The Civil War," was used in a design…
Higher-Order Latent Trait Models for Cognitive Diagnosis
ERIC Educational Resources Information Center
de la Torre, Jimmy; Douglas, Jeffrey A.
2004-01-01
Higher-order latent traits are proposed for specifying the joint distribution of binary attributes in models for cognitive diagnosis. This approach results in a parsimonious model for the joint distribution of a high-dimensional attribute vector that is natural in many situations when specific cognitive information is sought but a less informative…
Constrained variational calculus for higher order classical field theories
NASA Astrophysics Data System (ADS)
Campos, Cédric M.; de León, Manuel; Martín de Diego, David
2010-11-01
We develop an intrinsic geometrical setting for higher order constrained field theories. As a main tool we use an appropriate generalization of the classical Skinner-Rusk formalism. Some examples of applications are studied, in particular to the geometrical description of optimal control theory for partial differential equations.
Computer-Mediated Assessment of Higher-Order Thinking Development
ERIC Educational Resources Information Center
Tilchin, Oleg; Raiyn, Jamal
2015-01-01
Solving complicated problems in a contemporary knowledge-based society requires higher-order thinking (HOT). The most productive way to encourage development of HOT in students is through use of the Problem-based Learning (PBL) model. This model organizes learning by solving corresponding problems relative to study courses. Students are directed…
Building Higher-Order Markov Chain Models with EXCEL
ERIC Educational Resources Information Center
Ching, Wai-Ki; Fung, Eric S.; Ng, Michael K.
2004-01-01
Categorical data sequences occur in many applications such as forecasting, data mining and bioinformatics. In this note, we present higher-order Markov chain models for modelling categorical data sequences with an efficient algorithm for solving the model parameters. The algorithm can be implemented easily in a Microsoft EXCEL worksheet. We give a…
Using Higher Order Computer Tasks with Disadvantaged Students.
ERIC Educational Resources Information Center
Anderson, Neil
A pilot program initially designed for a 12-year-old girl with mild to moderate intellectual disabilities in higher order computer tasks was developed for a larger group of students with similar disabilities enrolled in fifth and sixth grades (ages 9-12) at three different schools. An examination of the original pilot study was undertaken to…
Developing Higher-Order Thinking Skills through WebQuests
ERIC Educational Resources Information Center
Polly, Drew; Ausband, Leigh
2009-01-01
In this study, 32 teachers participated in a year-long professional development project related to technology integration in which they designed and implemented a WebQuest. This paper describes the extent to which higher-order thinking skills (HOTS) and levels of technology implementation (LoTI) occur in the WebQuests that participants designed.…
Higher order microfibre modes for dielectric particle trapping and propulsion
Maimaiti, Aili; Truong, Viet Giang; Sergides, Marios; Gusachenko, Ivan; Nic Chormaic, Síle
2015-01-01
Optical manipulation in the vicinity of optical micro- and nanofibres has shown potential across several fields in recent years, including microparticle control, and cold atom probing and trapping. To date, most work has focussed on the propagation of the fundamental mode through the fibre. However, along the maximum mode intensity axis, higher order modes have a longer evanescent field extension and larger field amplitude at the fibre waist compared to the fundamental mode, opening up new possibilities for optical manipulation and particle trapping. We demonstrate a microfibre/optical tweezers compact system for trapping and propelling dielectric particles based on the excitation of the first group of higher order modes at the fibre waist. Speed enhancement of polystyrene particle propulsion was observed for the higher order modes compared to the fundamental mode for particles ranging from 1 μm to 5 μm in diameter. The optical propelling velocity of a single, 3 μm polystyrene particle was found to be 8 times faster under the higher order mode than the fundamental mode field for a waist power of 25 mW. Experimental data are supported by theoretical calculations. This work can be extended to trapping and manipulation of laser-cooled atoms with potential for quantum networks. PMID:25766925
Calculation of Moment Matrix Elements for Bilinear Quadrilaterals and Higher-Order Basis Functions
2016-01-06
B. M. Kolundzija and A. R. Djordjević, Electromagnetic Modeling of Composite Metallic and Dielectric Structures . Boston: Artech House, 2002...REPORT REPORT NO: NAWCADPAX/TR-2015/241 CALCULATION OF MOMENT MATRIX ELEMENTS FOR BILINEAR QUADRILATERALS AND HIGHER-ORDER BASIS...CALCULATION OF MOMENT MATRIX ELEMENTS FOR BILINEAR QUADRILATERALS AND HIGHER-ORDER BASIS FUNCTIONS by John S. Asvestas
Higher order time integration methods for two-phase flow
NASA Astrophysics Data System (ADS)
Kees, Christopher E.; Miller, Cass T.
Time integration methods that adapt in both the order of approximation and time step have been shown to provide efficient solutions to Richards' equation. In this work, we extend the same method of lines approach to solve a set of two-phase flow formulations and address some mass conservation issues from the previous work. We analyze these formulations and the nonlinear systems that result from applying the integration methods, placing particular emphasis on their index, range of applicability, and mass conservation characteristics. We conduct numerical experiments to study the behavior of the numerical models for three test problems. We demonstrate that higher order integration in time is more efficient than standard low-order methods for a variety of practical grids and integration tolerances, that the adaptive scheme successfully varies the step size in response to changing conditions, and that mass balance can be maintained efficiently using variable-order integration and an appropriately chosen numerical model formulation.
A Short Note on Rules and Higher Order Rules.
ERIC Educational Resources Information Center
Scandura, Joseph M.
This brief paper argues that structural analysis--an extended form of cognitive task analysis--demonstrates that both domain dependent and domain independent knowledge can be derived from specific content domains. It is noted that the major difference between the two is that lower order rules (specific knowledge) are derived directly from specific…
Lipkin method of particle-number restoration to higher orders
NASA Astrophysics Data System (ADS)
Wang, X. B.; Dobaczewski, J.; Kortelainen, M.; Yu, L. F.; Stoitsov, M. V.
2014-07-01
Background: On the mean-field level, pairing correlations are incorporated through the Bogoliubov-Valatin transformation, whereby the particle degrees of freedom are replaced by quasiparticles. This approach leads to a spontaneous breaking of the particle-number symmetry and mixing of states with different particle numbers. In order to restore the particle number, various methods have been employed, which are based on projection approaches before or after variation. Approximate variation-after-projection (VAP) schemes, utilizing the Lipkin method, have mostly been used within the Lipkin-Nogami prescription. Purpose: Without employing the Lipkin-Nogami prescription, and using, instead, states rotated in the gauge space, we derive the Lipkin method of particle-number restoration up to sixth order and we test the convergence and accuracy of the obtained expansion. Methods: We perform self-consistent calculations using the higher-order Lipkin method to restore the particle-number symmetry in the framework of superfluid nuclear energy-density functional theory. We also apply the Lipkin method to a schematic exactly solvable two-level pairing model. Results: Calculations performed in open-shell tin and lead isotopes show that the Lipkin method converges at fourth order and satisfactorily reproduces the VAP ground-state energies and energy kernels. Near closed shells, the higher-order Lipkin method cannot be applied because of a nonanalytic kink in the ground-state energies as a function of the particle number. Conclusions: In open-shell nuclei, the higher-order Lipkin method provides a good approximation to the exact VAP energies. The method is computationally inexpensive, making it particularly suitable, for example, for future optimizations of the nuclear energy density functionals and simultaneous restoration of different symmetries.
A higher order theory of laminated composite cylindrical shells
NASA Technical Reports Server (NTRS)
Krishna Murthy, A. V.; Reddy, T. S. R.
1986-01-01
A new higher order theory has been proposed for the analysis of composite cylindrical shells. The formulation allows for arbitrary variation of inplane displacements. Governing equations are presented in the form of a hierarchy of sets of partial differential equations. Each set describes the shell behavior to a certain degree of approximation. The natural frequencies of simply-supported isotropic and laminated shells and stresses in a ring loaded composite shell have been determined to various orders of approximation and compared with three dimensional solutions. These numerical studies indicate the improvements achievable in estimating the natural frequencies and the interlaminar shear stresses in laminated composite cylinders.
Sandia Higher Order Elements (SHOE) v 0.5 alpha
2013-09-24
SHOE is research code for characterizing and visualizing higher-order finite elements; it contains a framework for defining classes of interpolation techniques and element shapes; methods for interpolating triangular, quadrilateral, tetrahedral, and hexahedral cells using Lagrange and Legendre polynomial bases of arbitrary order; methods to decompose each element into domains of constant gradient flow (using a polynomial solver to identify critical points); and an isocontouring technique that uses this decomposition to guarantee topological correctness. Please note that this is an alpha release of research software and that some time has passed since it was actively developed; build- and run-time issues likely exist.
Learning in higher order Boltzmann machines using linear response.
Leisink, M A; Kappen, H J
2000-04-01
We introduce an efficient method for learning and inference in higher order Boltzmann machines. The method is based on mean field theory with the linear response correction. We compute the correlations using the exact and the approximated method for a fully connected third order network of ten neurons. In addition, we compare the results of the exact and approximate learning algorithm. Finally we use the presented method to solve the shifter problem. We conclude that the linear response approximation gives good results as long as the couplings are not too large.
Higher-order-mode fiber optimized for energetic soliton propagation.
Pedersen, Martin E V; Cheng, Ji; Charan, Kriti; Wang, Ke; Xu, Chris; Grüner-Nielsen, Lars; Jakobsen, Dan
2012-08-15
We describe the design optimization of a higher-order-mode (HOM) fiber for energetic soliton propagation at wavelengths below 1300 nm. A new HOM fiber is fabricated according to our design criteria. The HOM fiber is pumped at 1045 nm by an energetic femtosecond fiber laser. The soliton self-frequency shift process shifts the center wavelength of the soliton to 1085 nm. The soliton has a temporal duration of 216 fs and a pulse energy of 6.3 nJ. The demonstrated pulse energy is approximately six times higher than the previous record in a solid core fiber at wavelengths below 1300 nm.
Toddlers infer higher-order relational principles in causal learning.
Walker, Caren M; Gopnik, Alison
2014-01-01
Children make inductive inferences about the causal properties of individual objects from a very young age. When can they infer higher-order relational properties? In three experiments, we examined 18- to 30-month-olds' relational inferences in a causal task. Results suggest that at this age, children are able to infer a higher-order relational causal principle from just a few observations and use this inference to guide their own subsequent actions and bring about a novel causal outcome. Moreover, the children passed a revised version of the relational match-to-sample task that has proven very difficult for nonhuman primates. The findings are considered in light of their implications for understanding the nature of relational and causal reasoning, and their evolutionary origins.
Promoting higher order thinking skills using inquiry-based learning
NASA Astrophysics Data System (ADS)
Madhuri, G. V.; S. S. N Kantamreddi, V.; Goteti, L. N. S. Prakash
2012-05-01
Active learning pedagogies play an important role in enhancing higher order cognitive skills among the student community. In this work, a laboratory course for first year engineering chemistry is designed and executed using an inquiry-based learning pedagogical approach. The goal of this module is to promote higher order thinking skills in chemistry. Laboratory exercises are designed based on Bloom's taxonomy and a just-in-time facilitation approach is used. A pre-laboratory discussion outlining the theory of the experiment and its relevance is carried out to enable the students to analyse real-life problems. The performance of the students is assessed based on their ability to perform the experiment, design new experiments and correlate practical utility of the course module with real life. The novelty of the present approach lies in the fact that the learning outcomes of the existing experiments are achieved through establishing a relationship with real-world problems.
A higher-order-statistics-based approach to face detection
NASA Astrophysics Data System (ADS)
Li, Chunming; Li, Yushan; Wu, Ruihong; Li, Qiuming; Zhuang, Qingde; Zhang, Zhan
2005-02-01
A face detection method based on higher order statistics is proposed in this paper. Firstly, the object model and noise model are established to extract moving object from the background according to the fact that higher order statistics is nonsense to Gaussian noise. Secondly, the improved Sobel operator is used to extract the edge image of moving object. And a projection function is used to detect the face in the edge image. Lastly, PCA(Principle Component Analysis) method is used to do face recognition. The performance of the system is evaluated on the real video sequences. It is shown that the proposed method is simple and robust to the detection of human faces in the video sequences.
Higher order interactions in magneto-inductive waveguides
NASA Astrophysics Data System (ADS)
Syms, R. R. A.; Sydoruk, O.; Shamonina, E.; Solymar, L.
2007-03-01
The properties of periodic chains of magnetically coupled L-C resonators supporting magneto-inductive (MI) waves are examined in the case when non-nearest neighbour interactions are significant. The variation of the coupling coefficient with separation is measured using resonant elements based on printed circuit board inductors and surface mount capacitors, and used to predict the S-parameters and dispersion characteristics of magnetoinductive waveguides. Good agreement with experimental measurements is obtained when higher order interactions are included. The significance of non-nearest neighbour interactions in more general MI wave devices is then highlighted in an example problem involving reflection from a waveguide discontinuity, and the influence of higher order evanescent waves is discussed.
Higher order parabolic approximations of the reduced wave equation
NASA Technical Reports Server (NTRS)
Mcaninch, G. L.
1986-01-01
Asymptotic solutions of order k to the nth are developed for the reduced wave equation. Here k is a dimensionless wave number and n is the arbitrary order of the approximation. These approximations are an extension of geometric acoustics theory, and provide corrections to that theory in the form of multiplicative functions which satisfy parabolic partial differential equations. These corrections account for the diffraction effects caused by variation of the field normal to the ray path and the interaction of these transverse variations with the variation of the field along the ray. The theory is applied to the example of radiation from a piston, and it is demonstrated that the higher order approximations are more accurate for decreasing values of k.
A higher-order Robert-Asselin type time filter
NASA Astrophysics Data System (ADS)
Li, Yong; Trenchea, Catalin
2014-02-01
The Robert-Asselin (RA) time filter combined with leapfrog scheme is widely used in numerical models of weather and climate. It successfully suppresses the spurious computational mode associated with the leapfrog method, but it also weakly dampens the physical mode and degrades the numerical accuracy. The Robert-Asselin-Williams (RAW) time filter is a modification of the RA filter that reduces the undesired numerical damping of RA filter and increases the accuracy. We propose a higher-order Robert-Asselin (hoRA) type time filter which effectively suppresses the computational modes and achieves third-order accuracy with the same storage requirement as RAW filter. Like RA and RAW filters, the hoRA filter is non-intrusive, and so it would be easily implementable. The leapfrog scheme with hoRA filter is almost as accurate, stable and efficient as the intrusive third-order Adams-Bashforth (AB3) method.
Higher-order harmonics in bleached silver halide holograms
NASA Astrophysics Data System (ADS)
Bányász, I.
2006-09-01
A large number of plane wave holograms were recorded in Agfa-Gevaert 8E75HD holographic plates, at a wide range of bias exposures and fringe visibilities. The plates were processed by various combinations of developers (AAC, Pyrogallol and Catechol) and bleaching agents (R-9 and EDTA). The phase gratings were studied by phase-contrast microscopy, using a high-power immersion (100×) objective. The phase-contrast photomicrographs were Fourier analysed. Thus, first-, second-, and third-order modulations of the refractive index as a function of bias exposure and visibility of the recording interference pattern could be determined. The ratio of the amplitudes of higher-order modulations to that of the first-order can serve as a measure of the nonlinearity of the holographic recording.
Higher-order ionosphere modeling for CODE's next reprocessing activities
NASA Astrophysics Data System (ADS)
Lutz, S.; Schaer, S.; Meindl, M.; Dach, R.; Steigenberger, P.
2009-12-01
CODE (the Center for Orbit Determination in Europe) is a joint venture between the Astronomical Institute of the University of Bern (AIUB, Bern, Switzerland), the Federal Office of Topography (swisstopo, Wabern, Switzerland), the Federal Agency for Cartography and Geodesy (BKG, Frankfurt am Main, Germany), and the Institut für Astronomische und Phsyikalische Geodäsie of the Technische Universität München (IAPG/TUM, Munich, Germany). It acts as one of the global analysis centers of the International GNSS Service (IGS) and participates in the first IGS reprocessing campaign, a full reanalysis of GPS data collected since 1994. For a future reanalyis of the IGS data it is planned to consider not only first-order but also higher-order ionosphere terms in the space geodetic observations. There are several works (e.g. Fritsche et al. 2005), which showed a significant and systematic influence of these effects on the analysis results. The development version of the Bernese Software used at CODE is expanded by the ability to assign additional (scaling) parameters to each considered higher-order ionosphere term. By this, each correction term can be switched on and off on normal-equation level and, moreover, the significance of each correction term may be verified on observation level for different ionosphere conditions.
Orchestration of Molecular Information through Higher Order Chemical Recognition
NASA Astrophysics Data System (ADS)
Frezza, Brian M.
Broadly defined, higher order chemical recognition is the process whereby discrete chemical building blocks capable of specifically binding to cognate moieties are covalently linked into oligomeric chains. These chains, or sequences, are then able to recognize and bind to their cognate sequences with a high degree of cooperativity. Principally speaking, DNA and RNA are the most readily obtained examples of this chemical phenomenon, and function via Watson-Crick cognate pairing: guanine pairs with cytosine and adenine with thymine (DNA) or uracil (RNA), in an anti-parallel manner. While the theoretical principles, techniques, and equations derived herein apply generally to any higher-order chemical recognition system, in practice we utilize DNA oligomers as a model-building material to experimentally investigate and validate our hypotheses. Historically, general purpose information processing has been a task limited to semiconductor electronics. Molecular computing on the other hand has been limited to ad hoc approaches designed to solve highly specific and unique computation problems, often involving components or techniques that cannot be applied generally in a manner suitable for precise and predictable engineering. Herein, we provide a fundamental framework for harnessing high-order recognition in a modular and programmable fashion to synthesize molecular information process networks of arbitrary construction and complexity. This document provides a solid foundation for routinely embedding computational capability into chemical and biological systems where semiconductor electronics are unsuitable for practical application.
Higher order harmonic detection for exploring nonlinear interactions
Vasudevan, Rama K; Okatan, M. B.; Rajapaksa, Indrajit; Kim, Yunseok; Marincel, Dan; Trolier-McKinstry, Susan; Jesse, Stephen; Nagarajan, Valanoor; Kalinin, Sergei V
2013-01-01
Nonlinear dynamics underpin a vast array of physical phenomena ranging from interfacial motion to jamming transitions. In many cases, decoupling the contributions of competing or co-existing mechanisms to the system response can be achieved through investigation of higher order harmonics. Here, a method using band excitation scanning probe microscopy to investigate higher order harmonics of the electromechanical response, with nanometer scale spatial resolution is presented. The utility of the technique is demonstrated by probing the first three harmonics of strain for a well-known system, a model Pb(Zr1-xTix)O3 ferroelectric capacitor. It is shown that the second order harmonic response is correlated with the first harmonic response, whereas the third harmonic is not. Additionally, nanoscale measurements of the second harmonic response with field reveal significant deviations from Rayleigh-type models in the form of a much more complicated field dependence than is observed in the spatially averaged data. These results illustrate the versatility of combining proximal probe techniques with nth harmonic detection methods in exploring and decoupling nonlinear dynamics in a wide variety of nanoscale materials.
Higher order mode damping in an ALS test cavity
Jacob, A.F.; Lamberston, G.R. ); Barry, W. )
1990-06-01
The higher order mode attenuation scheme proposed for the Advanced Light Source accelerating cavities consists of two broad-band dampers placed 90{degrees} apart on the outer edge. In order to assess the damping efficiency a test assembly was built. The HOM damping was obtained by comparing the peak values of the transmission through the cavity for both the damped and the undamped case. Because of the high number of modes and frequency shifts due to the damping gear, the damping was assessed statistically, by averaging over several modes. In the frequency range from 1.5 to 5.5 GHz, average damping greater than 100 was obtained. 1 ref., 6 figs.
Higher-order automatic differentiation of mathematical functions
NASA Astrophysics Data System (ADS)
Charpentier, Isabelle; Dal Cappello, Claude
2015-04-01
Functions of mathematical physics such as the Bessel functions, the Chebyshev polynomials, the Gauss hypergeometric function and so forth, have practical applications in many scientific domains. On the one hand, differentiation formulas provided in reference books apply to real or complex variables. These do not account for the chain rule. On the other hand, based on the chain rule, the automatic differentiation has become a natural tool in numerical modeling. Nevertheless automatic differentiation tools do not deal with the numerous mathematical functions. This paper describes formulas and provides codes for the higher-order automatic differentiation of mathematical functions. The first method is based on Faà di Bruno's formula that generalizes the chain rule. The second one makes use of the second order differential equation they satisfy. Both methods are exemplified with the aforementioned functions.
Polymer quantization, stability and higher-order time derivative terms
NASA Astrophysics Data System (ADS)
Cumsille, Patricio; Reyes, Carlos M.; Ossandon, Sebastian; Reyes, Camilo
2016-03-01
The possibility that fundamental discreteness implicit in a quantum gravity theory may act as a natural regulator for ultraviolet singularities arising in quantum field theory has been intensively studied. Here, along the same expectations, we investigate whether a nonstandard representation called polymer representation can smooth away the large amount of negative energy that afflicts the Hamiltonians of higher-order time derivative theories, rendering the theory unstable when interactions come into play. We focus on the fourth-order Pais-Uhlenbeck model which can be reexpressed as the sum of two decoupled harmonic oscillators one producing positive energy and the other negative energy. As expected, the Schrödinger quantization of such model leads to the stability problem or to negative norm states called ghosts. Within the framework of polymer quantization we show the existence of new regions where the Hamiltonian can be defined well bounded from below.
An improved higher order panel method for linearized supersonic flow
NASA Technical Reports Server (NTRS)
Ehlers, F. E.; Epton, M. A.; Johnson, F. T.; Magnus, A. E.; Rubbert, P. E.
1978-01-01
An improved higher order panel method for linearized supersonic flow is described. Each panel, defined by four points on the surface, is divided into eight subpanels in such a way that all subpanel and panel edges are contiguous. By prescribing a quadratic distribution of the doublet on each subpanel, the doublet strength is made strictly continuous on the paneled surface. A linear source distribution is also used. Numerical results are smoother and in better agreement with experiment than the previous method with less strict continuity. A brief discussion of superinclined panels used to eliminate interior interference in nacelles is included.
A new theorem on higher order derivatives of Lyapunov functions.
Meigoli, Vahid; Nikravesh, Seyyed Kamaleddin Yadavar
2009-04-01
The Lyapunov stability analysis method for nonlinear dynamic systems requires a non positive first derivative of the Lyapunov functions along the system's trajectories. In this paper, a new method is developed to relax this requirement. A new sufficient condition is developed for the stability analysis of nonlinear systems, introducing some inequalities for higher order derivatives of the Lyapunov function. The differential inequalities can be considered as a new controllable canonical form linear time invariant system with negative inputs. The stability analysis of a given nonlinear system is then reduced to check if the characteristic equation for the new linear time invariant system is Hurwitz. Some examples are presented to establish the approach.
Higher order software - A methodology for defining software
NASA Technical Reports Server (NTRS)
Hamilton, M.; Zeldin, S.
1976-01-01
Higher order software (HOS) is concerned only with computable functions and relationships. The HOS methodology can be used for the definition of software for multiprogrammed, multiprocessor, or multicomputer systems. A description of HOS methodology is presented, giving attention to questions of formulation, interface correctness, specification language principles, and HOS analyzers. Aspects of system design are considered, and details of software management are discussed. Attention is given to modularity as defined by HOS, frozen module management, the assembly control supervisor, and aspects of reliability and efficiency.
Programming real-time executives in higher order language
NASA Technical Reports Server (NTRS)
Foudriat, E. C.
1982-01-01
Methods by which real-time executive programs can be implemented in a higher order language are discussed, using HAL/S and Path Pascal languages as program examples. Techniques are presented by which noncyclic tasks can readily be incorporated into the executive system. Situations are shown where the executive system can fail to meet its task scheduling and yet be able to recover either by rephasing the clock or stacking the information for later processing. The concept of deadline processing is shown to enable more effective mixing of time and information synchronized systems.
Higher-order modes in the APS storage ring waveguides
Brauer, S.O.; Kustom, R.L.
1993-07-01
Twelve higher-order modes (HOMs) in the single-cell accelerating cavities for the Advanced Photon Source (APS) storage ring were calculated to have complex impedances that will cause coupled-bunched instabilities near or below the 300mA positron current which is the design goal. Some of these modes couple, through the coupling loop, from the storage ring cavity into the waveguide. This study investigates the transmission of these modes from the cavity into the waveguide. The standing wave ratio (VSWR) of a WR2300 hybrid waveguide component has been measured at each HOM frequency, and its effect on the transmitted modes in the waveguide is studied.
Higher Order Mode Properties of Superconducting Two-Spoke Cavities
Hopper, C. S.; Delayen, J. R.; Olave, R. G.
2011-07-01
Multi-Spoke cavities lack the cylindrical symmetry that many other cavity types have, which leads to a more complex Higher Order Mode (HOM) spectrum. In addition, spoke cavities offer a large velocity acceptance which means we must perform a detailed analysis of the particle velocity dependence for each mode's R/Q. We present here a study of the HOM properties of two-spoke cavities designed for high-velocity applications. Frequencies, R/Q and field profiles of HOMs have been calculated and are reported.
Extension of MINOTAUR to higher-order spatial functions
Pevey, R.E.
1999-09-01
MINOTAUR, a generalized multidimensional geometry discrete ordinates kernel that can be used to calculate the particle flow through a complicated geometrical arrangement of materials, has been extended to use higher-order within-node spatial flux expansions. MINOTAUR is an improved version of the CENTAUR code, which was developed at the Savannah River Site by DeHart, Pevey, and Parish for flat intranode flux distributions. CENTAUR was later extended to linear spatial flux shapes by Grove and Pevey. Both of these codes were limited to two-dimensional generalized geometries, for which the regions are bounded by arbitrarily oriented line segments.
Higher order temporal finite element methods through mixed formalisms.
Kim, Jinkyu
2014-01-01
The extended framework of Hamilton's principle and the mixed convolved action principle provide new rigorous weak variational formalism for a broad range of initial boundary value problems in mathematical physics and mechanics. In this paper, their potential when adopting temporally higher order approximations is investigated. The classical single-degree-of-freedom dynamical systems are primarily considered to validate and to investigate the performance of the numerical algorithms developed from both formulations. For the undamped system, all the algorithms are symplectic and unconditionally stable with respect to the time step. For the damped system, they are shown to be accurate with good convergence characteristics.
Ordering structured populations in multiplayer cooperation games
Peña, Jorge; Wu, Bin; Traulsen, Arne
2016-01-01
Spatial structure greatly affects the evolution of cooperation. While in two-player games the condition for cooperation to evolve depends on a single structure coefficient, in multiplayer games the condition might depend on several structure coefficients, making it difficult to compare different population structures. We propose a solution to this issue by introducing two simple ways of ordering population structures: the containment order and the volume order. If population structure is greater than population structure in the containment or the volume order, then can be considered a stronger promoter of cooperation. We provide conditions for establishing the containment order, give general results on the volume order, and illustrate our theory by comparing different models of spatial games and associated update rules. Our results hold for a large class of population structures and can be easily applied to specific cases once the structure coefficients have been calculated or estimated. PMID:26819335
Laser-PlasmaWakefield Acceleration with Higher Order Laser Modes
Geddes, C.G.R.; Cormier-Michel, E.; Esarey, E.; Schroeder, C.B.; Mullowney, P.; Paul, K.; Cary, J.R.; Leemans, W.P.
2010-06-01
Laser-plasma collider designs point to staging of multiple accelerator stages at the 10 GeV level, which are to be developed on the upcoming BELLA laser, while Thomson Gamma source designs use GeV stages, both requiring efficiency and low emittance. Design and scaling of stages operating in the quasi-linear regime to address these needs are presented using simulations in the VORPAL framework. In addition to allowing symmetric acceleration of electrons and positrons, which is important for colliders, this regime has the property that the plasma wakefield is proportional to the transverse gradient of the laser intensity profile. We demonstrate use of higher order laser modes to tailor the laser pulse and hence the transverse focusing forces in the plasma. In particular, we show that by using higher order laser modes, we can reduce the focusing fields and hence increase the matched electron beam radius, which is important to increased charge and efficiency, while keeping the low bunch emittance required for applications.
Higher-Order Interference in Extensions of Quantum Theory
NASA Astrophysics Data System (ADS)
Lee, Ciarán M.; Selby, John H.
2016-10-01
Quantum interference, manifest in the two slit experiment, lies at the heart of several quantum computational speed-ups and provides a striking example of a quantum phenomenon with no classical counterpart. An intriguing feature of quantum interference arises in a variant of the standard two slit experiment, in which there are three, rather than two, slits. The interference pattern in this set-up can be written in terms of the two and one slit patterns obtained by blocking one, or more, of the slits. This is in stark contrast with the standard two slit experiment, where the interference pattern cannot be written as a sum of the one slit patterns. This was first noted by Rafael Sorkin, who raised the question of why quantum theory only exhibits irreducible interference in the two slit experiment. One approach to this problem is to compare the predictions of quantum theory to those of operationally-defined `foil' theories, in the hope of determining whether theories that do exhibit higher-order interference suffer from pathological—or at least undesirable—features. In this paper two proposed extensions of quantum theory are considered: the theory of Density Cubes proposed by Dakić, Paterek and Brukner, which has been shown to exhibit irreducible interference in the three slit set-up, and the Quartic Quantum Theory of Życzkowski. The theory of Density Cubes will be shown to provide an advantage over quantum theory in a certain computational task and to posses a well-defined mechanism which leads to the emergence of quantum theory—analogous to the emergence of classical physics from quantum theory via decoherence. Despite this, the axioms used to define Density Cubes will be shown to be insufficient to uniquely characterise the theory. In comparison, Quartic Quantum Theory is a well-defined theory and we demonstrate that it exhibits irreducible interference to all orders. This feature of Życzkowski's theory is argued not to be a genuine phenomenon, but to
Visualizing Higher Order Finite Elements: FY05 Yearly Report.
Thompson, David; Pebay, Philippe Pierre
2005-11-01
This report contains an algorithm for decomposing higher-order finite elementsinto regions appropriate for isosurfacing and proves the conditions under which thealgorithm will terminate. Finite elements are used to create piecewise polynomialapproximants to the solution of partial differential equations for which no analyticalsolution exists. These polynomials represent fields such as pressure, stress, and mo-mentim. In the past, these polynomials have been linear in each parametric coordinate.Each polynomial coefficient must be uniquely determined by a simulation, and thesecoefficients are called degrees of freedom. When there are not enough degrees of free-dom, simulations will typically fail to produce a valid approximation to the solution.Recent work has shown that increasing the number of degrees of freedom by increas-ing the order of the polynomial approximation (instead of increasing the number offinite elements, each of which has its own set of coefficients) can allow some typesof simulations to produce a valid approximation with many fewer degrees of freedomthan increasing the number of finite elements alone. However, once the simulation hasdetermined the values of all the coefficients in a higher-order approximant, tools donot exist for visual inspection of the solution.This report focuses on a technique for the visual inspection of higher-order finiteelement simulation results based on decomposing each finite element into simplicialregions where existing visualization algorithms such as isosurfacing will work. Therequirements of the isosurfacing algorithm are enumerated and related to the placeswhere the partial derivatives of the polynomial become zero. The original isosurfacingalgorithm is then applied to each of these regions in turn.3 AcknowledgementThe authors would like to thank David Day and Louis Romero for their insight into poly-nomial system solvers and the LDRD Senior Council for the opportunity to pursue thisresearch. The authors were
Higher-Order Interference in Extensions of Quantum Theory
NASA Astrophysics Data System (ADS)
Lee, Ciarán M.; Selby, John H.
2017-01-01
Quantum interference, manifest in the two slit experiment, lies at the heart of several quantum computational speed-ups and provides a striking example of a quantum phenomenon with no classical counterpart. An intriguing feature of quantum interference arises in a variant of the standard two slit experiment, in which there are three, rather than two, slits. The interference pattern in this set-up can be written in terms of the two and one slit patterns obtained by blocking one, or more, of the slits. This is in stark contrast with the standard two slit experiment, where the interference pattern cannot be written as a sum of the one slit patterns. This was first noted by Rafael Sorkin, who raised the question of why quantum theory only exhibits irreducible interference in the two slit experiment. One approach to this problem is to compare the predictions of quantum theory to those of operationally-defined `foil' theories, in the hope of determining whether theories that do exhibit higher-order interference suffer from pathological—or at least undesirable—features. In this paper two proposed extensions of quantum theory are considered: the theory of Density Cubes proposed by Dakić, Paterek and Brukner, which has been shown to exhibit irreducible interference in the three slit set-up, and the Quartic Quantum Theory of Życzkowski. The theory of Density Cubes will be shown to provide an advantage over quantum theory in a certain computational task and to posses a well-defined mechanism which leads to the emergence of quantum theory—analogous to the emergence of classical physics from quantum theory via decoherence. Despite this, the axioms used to define Density Cubes will be shown to be insufficient to uniquely characterise the theory. In comparison, Quartic Quantum Theory is a well-defined theory and we demonstrate that it exhibits irreducible interference to all orders. This feature of Życzkowski's theory is argued not to be a genuine phenomenon, but to
Higher-order spectra for identification of nonlinear modal coupling
NASA Astrophysics Data System (ADS)
Hickey, Daryl; Worden, Keith; Platten, Michael F.; Wright, Jan R.; Cooper, Jonathan E.
2009-05-01
Over the past four decades considerable work has been done in the area of power spectrum estimation. The information contained within the power spectrum relates to a signal's autocorrelation or 'second-order statistics'. The power spectrum provides a complete statistical description of a Gaussian process; however, a problem with this information is that it is phase blind. This problem is addressed if one turns to a system's frequency response function (FRF). The FRF graphs the magnitude and phase of the frequency response of a system; in order to do this it requires information regarding the frequency content of the input and output signals. Situations arise in science and engineering whereby signal analysts are required to look beyond second-order statistics and analyse a signal's higher-order statistics (HOS). HOS or spectra give information on a signal's deviation from Gaussianity and consequently are a good indicator function for the presence of nonlinearity within a system. One of the main problems in nonlinear system identification is that of high modal density. Many modelling schemes involve making some expansion of the nonlinear restoring force in terms of polynomial or other basis terms. If more than one degree-of-freedom is involved this becomes a multivariate problem and the number of candidate terms in the expansion grows explosively with the order of nonlinearity and the number of degrees-of-freedom. This paper attempts to use HOS to detect and qualify nonlinear behaviour for a number of symmetrical and asymmetrical systems over a range of degrees-of-freedom. In doing so the paper also attempts to show that HOS are a more sensitive tool than the FRF in detecting nonlinearity. Furthermore, the object of this paper is to try and identify which modes couple in a nonlinear manner in order to reduce the number of candidate coupling terms, for a model, as much as possible. The bispectrum method has previously been applied to simple low-DOF systems with high
Higher Order Mode Heating Analysis for the ILC Superconducting Linacs
Bane, K.L.F.; Nantista, C.; Adolphsen, C.; /SLAC
2010-10-27
The superconducting cavities and interconnects in the 11 km long linacs of the International Linear Collider (ILC) are designed to operate at 2K, where cooling costs are very expensive. It is thus important to minimize cryogenic heat loads. In addition to an unavoidable static load and the dynamic load of the fundamental 1.3 GHz accelerating rf, a further heat source is presented by the higher order mode (HOM) power deposited by the beam. Such modes will be damped by specially designed HOM couplers attached to the cavities (for trapped modes), and by ceramic dampers at 70K that are located between the eight or nine cavity cryomodules (for propagating modes). Brute force calculation of the higher frequency modes excited in a string of cryomodules is limited by computing capacity (see, e.g. [1]). M. Liepe has calculated {approx} 400 longitudinal TM modes in 3 superconducting cavities plus absorbers, up to 8 GHz [2]. Joestingmeier, et al., have used a ray tracing calculation to find the effect at higher frequencies, specifically in the range of tens of GHz and above [3]. In this report we present a scattering matrix approach, which we apply to an rf unit comprising 26 cavities and 3 absorbers. We perform calculations at sample frequencies (up to 20 GHz) to predict the effectiveness of the ceramic dampers in limiting HOM heat deposition at 2K.
NASA Astrophysics Data System (ADS)
Polyanskii, Peter V.; Felde, Christina V.; Konovchuk, Alexey V.; Oleksyuk, Maxim V.
2015-11-01
Recording nonlinearity is conventionally considered as the source of noise in holographic imaging. Important exclusion from this general statement is nonlinear holographic associative memory, where the quadratic recording nonlinearity causes true brightness rendering and the possibility for associative coupling and reconstructing optical signals of arbitrary complexity which are stored at the same carrier without interference. In this paper we discuss the role of nonlinearities of an amplitude response of a hologram of the orders higher than the quadratic one in implementing the second-ordered holographic associative memory. We show that higher-order nonlinearities are also involved in implementing this type of memory. This conclusion may be of importance for interpretation of biological/human memory also. The highlight of our study is the conclusion that reconstruction of the complex conjugate heteroassociative response is provided directly, viz. by the set of specified by us pseudogratings, rather than by the mechanism of sequential diffractions.
Dependable software through higher-order strategic programming.
Winter, Victor Lono; Fraij, Fares; Roach, Steve
2004-03-01
Program transformation is a restricted form of software construction that can be amenable to formal verification. When successful, the nature of the evidence provided by such a verification is considered strong and can constitute a major component of an argument that a high-consequence or safety-critical system meets its dependability requirements. This article explores the application of novel higher-order strategic programming techniques to the development of a portion of a class loader for a restricted implementation of the Java Virtual Machine (JVM). The implementation is called the SSP and is intended for use in high-consequence safety-critical embedded systems. Verification of the strategic program using ACL2 is also discussed.
A higher-order theory of emotional consciousness
LeDoux, Joseph E.; Brown, Richard
2017-01-01
Emotional states of consciousness, or what are typically called emotional feelings, are traditionally viewed as being innately programmed in subcortical areas of the brain, and are often treated as different from cognitive states of consciousness, such as those related to the perception of external stimuli. We argue that conscious experiences, regardless of their content, arise from one system in the brain. In this view, what differs in emotional and nonemotional states are the kinds of inputs that are processed by a general cortical network of cognition, a network essential for conscious experiences. Although subcortical circuits are not directly responsible for conscious feelings, they provide nonconscious inputs that coalesce with other kinds of neural signals in the cognitive assembly of conscious emotional experiences. In building the case for this proposal, we defend a modified version of what is known as the higher-order theory of consciousness. PMID:28202735
Efficient multiple time-stepping algorithms of higher order
NASA Astrophysics Data System (ADS)
Demirel, Abdullah; Niegemann, Jens; Busch, Kurt; Hochbruck, Marlis
2015-03-01
Multiple time-stepping (MTS) algorithms allow to efficiently integrate large systems of ordinary differential equations, where a few stiff terms restrict the timestep of an otherwise non-stiff system. In this work, we discuss a flexible class of MTS techniques, based on multistep methods. Our approach contains several popular methods as special cases and it allows for the easy construction of novel and efficient higher-order MTS schemes. In addition, we demonstrate how to adapt the stability contour of the non-stiff time-integration to the physical system at hand. This allows significantly larger timesteps when compared to previously known multistep MTS approaches. As an example, we derive novel predictor-corrector (PCMTS) schemes specifically optimized for the time-integration of damped wave equations on locally refined meshes. In a set of numerical experiments, we demonstrate the performance of our scheme on discontinuous Galerkin time-domain (DGTD) simulations of Maxwell's equations.
A higher-order-mode erbium-doped-fiber amplifier.
Nicholson, J W; Fini, J M; DeSantolo, A M; Monberg, E; DiMarcello, F; Fleming, J; Headley, C; DiGiovanni, D J; Ghalmi, S; Ramachandran, S
2010-08-16
We demonstrate the first erbium-doped fiber amplifier operating in a single, large-mode area, higher-order mode. A high-power, fundamental-mode, Raman fiber laser operating at 1480 nm was used as a pump source. Using a UV-written, long-period grating, both pump and 1564 nm signal were converted to the LP(0,10) mode, which had an effective area of 2700 microm(2) at 1550 nm. A maximum output power of 5.8 W at 1564 nm with more than 20 dB of gain in a 2.68 m long amplifier was obtained. The mode profile was undistorted at the highest output power.
Higher Order Intentionality Tasks Are Cognitively More Demanding.
Lewis, Penelope A; Birch, Amy; Hall, Alexander; Dunbar, R I M
2017-03-13
A central assumption that underpins much of the discussion of the role played by social cognition in brain evolution is that social cognition is unusually cognitively demanding. This assumption has never been tested. Here, we use a task in which participants read stories and then answered questions about the stories in a behavioural experiment (39 participants) and an fMRI experiment (17 participants) to show that mentalising requires more time for responses than factual memory of a matched complexity and also that higher orders of mentalising is disproportionately more demanding and requires the recruitment of more neurons in brain regions known to be associated with theory of mind, including insula, posterior STS, temporal pole, and cerebellum. These results have significant implications both for models of brain function and for models of brain evolution.
A higher-order theory of emotional consciousness.
LeDoux, Joseph E; Brown, Richard
2017-03-07
Emotional states of consciousness, or what are typically called emotional feelings, are traditionally viewed as being innately programmed in subcortical areas of the brain, and are often treated as different from cognitive states of consciousness, such as those related to the perception of external stimuli. We argue that conscious experiences, regardless of their content, arise from one system in the brain. In this view, what differs in emotional and nonemotional states are the kinds of inputs that are processed by a general cortical network of cognition, a network essential for conscious experiences. Although subcortical circuits are not directly responsible for conscious feelings, they provide nonconscious inputs that coalesce with other kinds of neural signals in the cognitive assembly of conscious emotional experiences. In building the case for this proposal, we defend a modified version of what is known as the higher-order theory of consciousness.
Higher order statistical moment application for solar PV potential analysis
NASA Astrophysics Data System (ADS)
Basri, Mohd Juhari Mat; Abdullah, Samizee; Azrulhisham, Engku Ahmad; Harun, Khairulezuan
2016-10-01
Solar photovoltaic energy could be as alternative energy to fossil fuel, which is depleting and posing a global warming problem. However, this renewable energy is so variable and intermittent to be relied on. Therefore the knowledge of energy potential is very important for any site to build this solar photovoltaic power generation system. Here, the application of higher order statistical moment model is being analyzed using data collected from 5MW grid-connected photovoltaic system. Due to the dynamic changes of skewness and kurtosis of AC power and solar irradiance distributions of the solar farm, Pearson system where the probability distribution is calculated by matching their theoretical moments with that of the empirical moments of a distribution could be suitable for this purpose. On the advantage of the Pearson system in MATLAB, a software programming has been developed to help in data processing for distribution fitting and potential analysis for future projection of amount of AC power and solar irradiance availability.
Intermediary LEO propagation including higher order zonal harmonics
NASA Astrophysics Data System (ADS)
Hautesserres, Denis; Lara, Martin
2017-04-01
Two new intermediary orbits of the artificial satellite problem are proposed. The analytical solutions include higher order effects of the geopotential, and are obtained by means of a torsion transformation applied to the quasi-Keplerian system resulting after the elimination of the parallax simplification, for the first intermediary, and after the elimination of the parallax and perigee simplifications, for the second one. The new intermediaries perform notably well for low Earth orbits propagation, are free from special functions, and result advantageous, both in accuracy and efficiency, when compared to the standard Cowell integration of the J_2 problem, thus providing appealing alternatives for onboard, short-term, orbit propagation under limited computational resources.
Higher order mode propagation in nonuniform circular ducts
NASA Technical Reports Server (NTRS)
Cho, Y. C.; Ingard, K. U.
1980-01-01
Higher order mode propagation in a nonuniform circular duct without mean flow was investigated. An approximate wave equation is derived on the assumptions that the duct cross section varies slowly and that mode conversion is negligible. Exact closed form solutions are obtained for a particular class of converging-diverging circular duct which referred to as 'circular cosh duct.' Numerical results are presented in terms of the transmission loss for the various duct shapes and frequencies. The results are applicable to multimodal propagation, single mode propagation, and sound radiation from certain types of contoured inlet ducts, or of sound propagation in a converging-diverging duct of somewhat different shape from a cosh duct.
Higher order mode propagation in nonuniform circular ducts
NASA Technical Reports Server (NTRS)
Cho, Y. C.; Ingard, K. U.
1980-01-01
This paper presents an analytical investigation of higher order mode propagation in a nonuniform circular duct without mean flow. An approximate wave equation is derived on the assumptions that the duct cross section varies slowly and that mode conversion is negligible. Exact closed form solutions are obtained for a particular class of converging-diverging circular duct which is here referred to as 'circular cosh duct'. Numerical results are presentd in terms of the transmission loss for the various duct shapes and frequencies. The results are applicable to studies of multimodal propagation as well as single mode propagation. The results are also applicable to studies of sound radiation from certain types of contoured inlet ducts, or of sound propagation in a converging-diverging duct of somewhat different shape from a cosh duct.
Higher-order resonances in a Stark decelerator
Meerakker, Sebastiaan Y.T. van de; Bethlem, Hendrick L.; Vanhaecke, Nicolas; Meijer, Gerard
2005-05-15
The motion of polar molecules can be controlled by time-varying inhomogeneous electric fields. In a Stark decelerator, this is exploited to select a fraction of a molecular beam that is accelerated, transported, or decelerated. Phase stability ensures that the selected bunch of molecules is kept together throughout the deceleration process. In this paper an extended description of phase stability in a Stark decelerator is given, including higher-order effects. This analysis predicts a wide variety of resonances that originate from the spatial and temporal periodicity of the electric fields. These resonances are experimentally observed using a beam of OH ({sup 2}{pi}{sub 3/2},v=0,J=3/2) radicals passing through a Stark decelerator.
Inflationary scenarios in Starobinsky model with higher order corrections
Artymowski, Michał; Lalak, Zygmunt; Lewicki, Marek
2015-06-17
We consider the Starobinsky inflation with a set of higher order corrections parametrised by two real coefficients λ{sub 1} ,λ{sub 2}. In the Einstein frame we have found a potential with the Starobinsky plateau, steep slope and possibly with an additional minimum, local maximum or a saddle point. We have identified three types of inflationary behaviour that may be generated in this model: i) inflation on the plateau, ii) at the local maximum (topological inflation), iii) at the saddle point. We have found limits on parameters λ{sub i} and initial conditions at the Planck scale which enable successful inflation and disable eternal inflation at the plateau. We have checked that the local minimum away from the GR vacuum is stable and that the field cannot leave it neither via quantum tunnelling nor via thermal corrections.
Pulse transmission transmitter including a higher order time derivate filter
Dress, Jr., William B.; Smith, Stephen F.
2003-09-23
Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission transmitter includes: a clock; a pseudorandom polynomial generator coupled to the clock, the pseudorandom polynomial generator having a polynomial load input; an exclusive-OR gate coupled to the pseudorandom polynomial generator, the exclusive-OR gate having a serial data input; a programmable delay circuit coupled to both the clock and the exclusive-OR gate; a pulse generator coupled to the programmable delay circuit; and a higher order time derivative filter coupled to the pulse generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.
Vehicle track segmentation using higher order random fields
Quach, Tu -Thach
2017-01-09
Here, we present an approach to segment vehicle tracks in coherent change detection images, a product of combining two synthetic aperture radar images taken at different times. The approach uses multiscale higher order random field models to capture track statistics, such as curvatures and their parallel nature, that are not currently utilized in existing methods. These statistics are encoded as 3-by-3 patterns at different scales. The model can complete disconnected tracks often caused by sensor noise and various environmental effects. Coupling the model with a simple classifier, our approach is effective at segmenting salient tracks. We improve the F-measure onmore » a standard vehicle track data set to 0.963, up from 0.897 obtained by the current state-of-the-art method.« less
Inflationary scenarios in Starobinsky model with higher order corrections
Artymowski, Michał; Lalak, Zygmunt; Lewicki, Marek E-mail: Zygmunt.Lalak@fuw.edu.pl
2015-06-01
We consider the Starobinsky inflation with a set of higher order corrections parametrised by two real coefficients λ{sub 1} , λ{sub 2}. In the Einstein frame we have found a potential with the Starobinsky plateau, steep slope and possibly with an additional minimum, local maximum or a saddle point. We have identified three types of inflationary behaviour that may be generated in this model: i) inflation on the plateau, ii) at the local maximum (topological inflation), iii) at the saddle point. We have found limits on parameters λ{sub i} and initial conditions at the Planck scale which enable successful inflation and disable eternal inflation at the plateau. We have checked that the local minimum away from the GR vacuum is stable and that the field cannot leave it neither via quantum tunnelling nor via thermal corrections.
Methods and framework for visualizing higher-order finite elements.
Schroeder, William J; Bertel, François; Malaterre, Mathieu; Thompson, David; Pébay, Philippe P; O'Bara, Robert; Tendulkar, Saurabh
2006-01-01
The finite element method is an important, widely used numerical technique for solving partial differential equations. This technique utilizes basis functions for approximating the geometry and the variation of the solution field over finite regions, or elements, of the domain. These basis functions are generally formed by combinations of polynomials. In the past, the polynomial order of the basis has been low-typically of linear and quadratic order. However, in recent years so-called p and hp methods have been developed, which may elevate the order of the basis to arbitrary levels with the aim of accelerating the convergence of the numerical solution. The increasing complexity of numerical basis functions poses a significant challenge to visualization systems. In the past, such systems have been loosely coupled to simulation packages, exchanging data via file transfer, and internally reimplementing the basis functions in order to perform interpolation and implement visualization algorithms. However, as the basis functions become more complex and, in some cases, proprietary in nature, it becomes increasingly difficult if not impossible to reimplement them within the visualization system. Further, most visualization systems typically process linear primitives, in part to take advantage of graphics hardware and, in part, due to the inherent simplicity of the resulting algorithms. Thus, visualization of higher-order finite elements requires tessellating the basis to produce data compatible with existing visualization systems. In this paper, we describe adaptive methods that automatically tessellate complex finite element basis functions using a flexible and extensible software framework. These methods employ a recursive, edge-based subdivision algorithm driven by a set of error metrics including geometric error, solution error, and error in image space. Further, we describe advanced pretessellation techniques that guarantees capture of the critical points of the
Higher-order nonclassical effects in fluctuating-loss channels
NASA Astrophysics Data System (ADS)
Bohmann, M.; Sperling, J.; Semenov, A. A.; Vogel, W.
2017-01-01
We study the evolution of higher-order nonclassicality and entanglement criteria in atmospheric fluctuating-loss channels. By formulating input-output relations for the matrix of moments, we investigate the influence of such channels on the corresponding quantumness criteria. This generalization of our previous work on Gaussian entanglement [M. Bohmann et al., Phys. Rev. A 94, 010302(R) (2016), 10.1103/PhysRevA.94.010302] not only exploits second-order-based scenarios, but it also provides a detailed investigation of nonclassicality and entanglement in non-Gaussian and multimode radiation fields undergoing a fluctuating attenuation. That is, various examples of criteria and states are studied in detail, unexpected effects, e.g., the dependency of the squeezing transfer on the coherent displacement, are discovered, and it is demonstrated that non-Gaussian entanglement can be more robust against atmospheric losses than Gaussian one. Additionally, we propose a detection scheme for measuring the considered moments after propagation through the atmosphere. Therefore, our results may help to develop, improve, and optimize non-Gaussian sources of quantum light for applications in free-space quantum communication.
Higher order acoustoelastic Lamb wave propagation in stressed plates.
Pei, Ning; Bond, Leonard J
2016-11-01
Modeling and experiments are used to investigate Lamb wave propagation in the direction perpendicular to an applied stress. Sensitivity, in terms of changes in velocity, for both symmetrical and anti-symmetrical modes was determined. Codes were developed based on analytical expressions for waves in loaded plates and they were used to give wave dispersion curves. The experimental system used a pair of compression wave transducers on variable angle wedges, with set separation, and variable frequency tone burst excitation, on an aluminum plate 0.16 cm thick with uniaxial applied loads. The loads, which were up to 600 με, were measured using strain gages. Model results and experimental data are in good agreement. It was found that the change in Lamb wave velocity, due to the acoustoelastic effect, for the S1 mode exhibits about ten times more sensitive, in terms of velocity change, than the traditional bulk wave measurements, and those performed using the fundamental Lamb modes. The data presented demonstrate the potential for the use of higher order Lamb modes for online industrial stress measurement in plate, and that the higher sensitivity seen offers potential for improved measurement systems.
Predicting perceptual learning from higher-order cortical processing.
Wang, Fang; Huang, Jing; Lv, Yaping; Ma, Xiaoli; Yang, Bin; Wang, Encong; Du, Boqi; Li, Wu; Song, Yan
2016-01-01
Visual perceptual learning has been shown to be highly specific to the retinotopic location and attributes of the trained stimulus. Recent psychophysical studies suggest that these specificities, which have been associated with early retinotopic visual cortex, may in fact not be inherent in perceptual learning and could be related to higher-order brain functions. Here we provide direct electrophysiological evidence in support of this proposition. In a series of event-related potential (ERP) experiments, we recorded high-density electroencephalography (EEG) from human adults over the course of learning in a texture discrimination task (TDT). The results consistently showed that the earliest C1 component (68-84ms), known to reflect V1 activity driven by feedforward inputs, was not modulated by learning regardless of whether the behavioral improvement is location specific or not. In contrast, two later posterior ERP components (posterior P1 and P160-350) over the occipital cortex and one anterior ERP component (anterior P160-350) over the prefrontal cortex were progressively modified day by day. Moreover, the change of the anterior component was closely correlated with improved behavioral performance on a daily basis. Consistent with recent psychophysical and imaging observations, our results indicate that perceptual learning can mainly involve changes in higher-level visual cortex as well as in the neural networks responsible for cognitive functions such as attention and decision making.
Emotion recognition from EEG using higher order crossings.
Petrantonakis, Panagiotis C; Hadjileontiadis, Leontios J
2010-03-01
Electroencephalogram (EEG)-based emotion recognition is a relatively new field in the affective computing area with challenging issues regarding the induction of the emotional states and the extraction of the features in order to achieve optimum classification performance. In this paper, a novel emotion evocation and EEG-based feature extraction technique is presented. In particular, the mirror neuron system concept was adapted to efficiently foster emotion induction by the process of imitation. In addition, higher order crossings (HOC) analysis was employed for the feature extraction scheme and a robust classification method, namely HOC-emotion classifier (HOC-EC), was implemented testing four different classifiers [quadratic discriminant analysis (QDA), k-nearest neighbor, Mahalanobis distance, and support vector machines (SVMs)], in order to accomplish efficient emotion recognition. Through a series of facial expression image projection, EEG data have been collected by 16 healthy subjects using only 3 EEG channels, namely Fp1, Fp2, and a bipolar channel of F3 and F4 positions according to 10-20 system. Two scenarios were examined using EEG data from a single-channel and from combined-channels, respectively. Compared with other feature extraction methods, HOC-EC appears to outperform them, achieving a 62.3% (using QDA) and 83.33% (using SVM) classification accuracy for the single-channel and combined-channel cases, respectively, differentiating among the six basic emotions, i.e., happiness, surprise, anger, fear, disgust, and sadness. As the emotion class-set reduces its dimension, the HOC-EC converges toward maximum classification rate (100% for five or less emotions), justifying the efficiency of the proposed approach. This could facilitate the integration of HOC-EC in human machine interfaces, such as pervasive healthcare systems, enhancing their affective character and providing information about the user's emotional status (e.g., identifying user's emotion
Cycles in finite samples and cumulative processes of higher orders
NASA Astrophysics Data System (ADS)
Klemeš, VíT.; Klemeš, Ivo
1988-01-01
The process formed by a sequence of cumulative departures from the mean or from some other constant (residual mass curve, cusum chart) is a popular tool for the representation and analysis of time series in many sciences, for example, in hydrology, climatology, economics, game theory. In these and other natural and social sciences, similar cumulative processes also often arise naturally; examples include fluctuations of storage in a dam with a constant release rate, lake levels, volume of glaciers, biomass, inventories, and bank accounts. Moreover, many natural economic and other phenomena may represent, or contain, components of cumulative processes of higher orders, i.e., cumulative processes of cumulative processes. In this paper we show that for a sample {yt(0)}≡{xt} of any finite size N, the pure cumulative process of nth order, yt(n)≡∑i=1t(yi(n-1) - μ(n-1)), where μ(n-1) is the sample mean of {yt(n-1)} and t=1, 2, …, N, converges for n→∞ to a sine wave with a period equal to an integral fraction of the sample size N. This happens for any initial sample {yt(0)} and the convergence is of an exponential order. For samples from most stochastic as well as deterministic processes, the period of the limiting sine wave is equal to the sample size N. This behavior is demonstrated by examples involving samples from various processes ranging from pure random series to various deterministic series and including time series of some natural processes such as streamflow, lake levels, and glacier volumes. The paper includes a demonstration of effects of noise superimposed on, and of error in the value of, sample mean on the rate of convergence, and a discussion of some practical implications of the phenomenon described; it brings together some aspects of the work of Slutzky (1937), Hurst (1951), and Yule (1926).
Regular solutions to higher order curvature Einstein Yang Mills systems in higher dimensions
NASA Astrophysics Data System (ADS)
Breitenlohner, Peter; Maison, Dieter; Tchrakian, D. H.
2005-12-01
We study regular, static, spherically symmetric solutions of Yang Mills theories employing higher order invariants of the field strength coupled to gravity in d dimensions. We consider models with only two such invariants characterized by integers p and q. These models depend on one dimensionless parameter α leading to one-parameter families of regular solutions, obtainable by numerical solution of the corresponding boundary value problem. Much emphasis is put on an analytical understanding of the numerical results.
Separating higher-order nonlinearities in transient absorption microscopy
NASA Astrophysics Data System (ADS)
Wilson, Jesse W.; Anderson, Miguel; Park, Jong Kang; Fischer, Martin C.; Warren, Warren S.
2015-08-01
The transient absorption response of melanin is a promising optically-accessible biomarker for distinguishing malignant melanoma from benign pigmented lesions, as demonstrated by earlier experiments on thin sections from biopsied tissue. The technique has also been demonstrated in vivo, but the higher optical intensity required for detecting these signals from backscattered light introduces higher-order nonlinearities in the transient response of melanin. These components that are higher than linear with respect to the pump or the probe introduce intensity-dependent changes to the overall response that complicate data analysis. However, our data also suggest these nonlinearities might be advantageous to in vivo imaging, in that different types of melanins have different nonlinear responses. Therefore, methods to separate linear from nonlinear components in transient absorption measurements might provide additional information to aid in the diagnosis of melanoma. We will discuss numerical methods for analyzing the various nonlinear contributions to pump-probe signals, with the ultimate objective of real time analysis using digital signal processing techniques. To that end, we have replaced the lock-in amplifier in our pump-probe microscope with a high-speed data acquisition board, and reprogrammed the coprocessor field-programmable gate array (FPGA) to perform lock-in detection. The FPGA lock-in offers better performance than the commercial instrument, in terms of both signal to noise ratio and speed. In addition, the flexibility of the digital signal processing approach enables demodulation of more complicated waveforms, such as spread-spectrum sequences, which has the potential to accelerate microscopy methods that rely on slow relaxation phenomena, such as photo-thermal and phosphorescence lifetime imaging.
Higher-order gravitational lensing reconstruction using Feynman diagrams
Jenkins, Elizabeth E.; Manohar, Aneesh V.; Yadav, Amit P.S.; Waalewijn, Wouter J. E-mail: amanohar@ucsd.edu E-mail: ayadav@physics.ucsd.edu
2014-09-01
We develop a method for calculating the correlation structure of the Cosmic Microwave Background (CMB) using Feynman diagrams, when the CMB has been modified by gravitational lensing, Faraday rotation, patchy reionization, or other distorting effects. This method is used to calculate the bias of the Hu-Okamoto quadratic estimator in reconstructing the lensing power spectrum up to O (φ{sup 4}) in the lensing potential φ. We consider both the diagonal noise TT TT, EB EB, etc. and, for the first time, the off-diagonal noise TT TE, TB EB, etc. The previously noted large O (φ{sup 4}) term in the second order noise is identified to come from a particular class of diagrams. It can be significantly reduced by a reorganization of the φ expansion. These improved estimators have almost no bias for the off-diagonal case involving only one B component of the CMB, such as EE EB.
Role of spatial higher order derivatives in momentum space entanglement
NASA Astrophysics Data System (ADS)
Kumar, S. Santhosh; Shankaranarayanan, S.
2017-03-01
We study the momentum space entanglement between different energy modes of interacting scalar fields propagating in general (D +1 )-dimensional flat space-time. As opposed to some of the recent works [V. Balasubramanian et al., Phys. Rev. D 86, 045014 (2012), 10.1103/PhysRevD.86.045014], we use a Lorentz invariant normalized ground state to obtain the momentum space entanglement entropy. We show that the Lorenz invariant definition removes the spurious power-law behavior obtained in the earlier works. More specifically, we show that the cubic interacting scalar field in (1 +1 ) dimensions leads to logarithmic divergence of the entanglement entropy and is consistent with the results from real space entanglement calculations. We study the effects of the introduction of the Lorentz violating higher derivative terms in the presence of a nonlinear self-interacting scalar field potential and show that the divergence structure of the entanglement entropy is improved in the presence of spatial higher derivative terms.
Higher-Order Finite Elements for Computing Thermal Radiation
NASA Technical Reports Server (NTRS)
Gould, Dana C.
2004-01-01
Two variants of the finite-element method have been developed for use in computational simulations of radiative transfers of heat among diffuse gray surfaces. Both variants involve the use of higher-order finite elements, across which temperatures and radiative quantities are assumed to vary according to certain approximations. In this and other applications, higher-order finite elements are used to increase (relative to classical finite elements, which are assumed to be isothermal) the accuracies of final numerical results without having to refine computational meshes excessively and thereby incur excessive computation times. One of the variants is termed the radiation sub-element (RSE) method, which, itself, is subject to a number of variations. This is the simplest and most straightforward approach to representation of spatially variable surface radiation. Any computer code that, heretofore, could model surface-to-surface radiation can incorporate the RSE method without major modifications. In the basic form of the RSE method, each finite element selected for use in computing radiative heat transfer is considered to be a parent element and is divided into sub-elements for the purpose of solving the surface-to-surface radiation-exchange problem. The sub-elements are then treated as classical finite elements; that is, they are assumed to be isothermal, and their view factors and absorbed heat fluxes are calculated accordingly. The heat fluxes absorbed by the sub-elements are then transferred back to the parent element to obtain a radiative heat flux that varies spatially across the parent element. Variants of the RSE method involve the use of polynomials to interpolate and/or extrapolate to approximate spatial variations of physical quantities. The other variant of the finite-element method is termed the integration method (IM). Unlike in the RSE methods, the parent finite elements are not subdivided into smaller elements, and neither isothermality nor other
A viscoelastic higher-order beam finite element
NASA Technical Reports Server (NTRS)
Johnson, Arthur R.; Tressler, Alexander
1996-01-01
A viscoelastic internal variable constitutive theory is applied to a higher-order elastic beam theory and finite element formulation. The behavior of the viscous material in the beam is approximately modeled as a Maxwell solid. The finite element formulation requires additional sets of nodal variables for each relaxation time constant needed by the Maxwell solid. Recent developments in modeling viscoelastic material behavior with strain variables that are conjugate to the elastic strain measures are combined with advances in modeling through-the-thickness stresses and strains in thick beams. The result is a viscous thick-beam finite element that possesses superior characteristics for transient analysis since its nodal viscous forces are not linearly dependent an the nodal velocities, which is the case when damping matrices are used. Instead, the nodal viscous forces are directly dependent on the material's relaxation spectrum and the history of the nodal variables through a differential form of the constitutive law for a Maxwell solid. The thick beam quasistatic analysis is explored herein as a first step towards developing more complex viscoelastic models for thick plates and shells, and for dynamic analyses. The internal variable constitutive theory is derived directly from the Boltzmann superposition theorem. The mechanical strains and the conjugate internal strains are shown to be related through a system of first-order, ordinary differential equations. The total time-dependent stress is the superposition of its elastic and viscous components. Equations of motion for the solid are derived from the virtual work principle using the total time-dependent stress. Numerical examples for the problems of relaxation, creep, and cyclic creep are carried out for a beam made from an orthotropic Maxwell solid.
SVP-like MADS-box protein from Carya cathayensis forms higher-order complexes.
Wang, Jingjing; Hou, Chuanming; Huang, Jianqin; Wang, Zhengjia; Xu, Yingwu
2015-03-01
To properly regulate plant flowering time and construct floral pattern, MADS-domain containing transcription factors must form multimers including homo- and hetero-dimers. They are also active in forming hetero-higher-order complexes with three to five different molecules. However, it is not well known if a MADS-box protein can also form homo-higher-order complex. In this study a biochemical approach is utilized to provide insight into the complex formation for an SVP-like MADS-box protein cloned from hickory. The results indicated that the protein is a heterogeneous higher-order complex with the peak population containing over 20 monomers. Y2H verified the protein to form homo-complex in yeast cells. Western blot of the hickory floral bud sample revealed that the protein exists in higher-order polymers in native. Deletion assays indicated that the flexible C-terminal residues are mainly responsible for the higher-order polymer formation and the heterogeneity. Current results provide direct biochemical evidences for an active MADS-box protein to be a high order complex, much higher than a quartermeric polymer. Analysis suggests that a MADS-box subset may be able to self-assemble into large complexes, and thereby differentiate one subfamily from the other in a higher-order structural manner. Present result is a valuable supplement to the action of mechanism for MADS-box proteins in plant development.
Analysis of wheezes using wavelet higher order spectral features.
Taplidou, Styliani A; Hadjileontiadis, Leontios J
2010-07-01
. This paves the way for the use of the wavelet higher order spectral features as an input vector to an efficient classifier. Apparently, this would integrate the intrinsic characteristics of wheezes within computerized diagnostic tools toward their more efficient evaluation.
ERIC Educational Resources Information Center
Shukla, Divya; Dungsungnoen, Aj Pattaradanai
2016-01-01
Higher order thinking skills (HOTS) has portrayed immense industry demand and the major goal of educational institution in imparting education is to inculcate higher order thinking skills. This compiles and mandate the institutions and instructor to develop the higher order thinking skills among students in order to prepare them for effective…
Image denoising using the higher order singular value decomposition.
Rajwade, Ajit; Rangarajan, Anand; Banerjee, Arunava
2013-04-01
In this paper, we propose a very simple and elegant patch-based, machine learning technique for image denoising using the higher order singular value decomposition (HOSVD). The technique simply groups together similar patches from a noisy image (with similarity defined by a statistically motivated criterion) into a 3D stack, computes the HOSVD coefficients of this stack, manipulates these coefficients by hard thresholding, and inverts the HOSVD transform to produce the final filtered image. Our technique chooses all required parameters in a principled way, relating them to the noise model. We also discuss our motivation for adopting the HOSVD as an appropriate transform for image denoising. We experimentally demonstrate the excellent performance of the technique on grayscale as well as color images. On color images, our method produces state-of-the-art results, outperforming other color image denoising algorithms at moderately high noise levels. A criterion for optimal patch-size selection and noise variance estimation from the residual images (after denoising) is also presented.
Pressure and higher-order spectra for homogeneous isotropic turbulence
NASA Technical Reports Server (NTRS)
Pullin, D. I.; Rogallo, R. S.
1994-01-01
The spectra of the pressure, and other higher-order quantities including the dissipation, the enstrophy, and the square of the longitudinal velocity derivative are computed using data obtained from direct numerical simulation of homogeneous isotropic turbulence at Taylor-Reynolds numbers R(sub lambda) in the range 38 - 170. For the pressure spectra we find reasonable collapse in the dissipation range (of the velocity spectrum) when scaled in Kolmogorov variables and some evidence, which is not conclusive, for the existence of a k(exp -7/3) inertial range where k = absolute value of K, is the modulus of the wavenumber. The power spectra of the dissipation, the enstrophy, and the square of the longitudinal velocity derivative separate in the dissipation range, but appear to converge together in the short inertial range of the simulations. A least-squares curve-fit in the dissipation range for one value of R(sub lambda) = 96 gives a form for the spectrum of the dissipation as k(exp 0)exp(-Ck eta), for k(eta) greater than 0.2, where eta is the Kolmogorov length and C is approximately equal to 2.5.
Higher order SVD analysis for dynamic texture synthesis.
Costantini, Roberto; Sbaiz, Luciano; Süsstrunk, Sabine
2008-01-01
Videos representing flames, water, smoke, etc., are often defined as dynamic textures: "textures" because they are characterized by the redundant repetition of a pattern and "dynamic" because this repetition is also in time and not only in space. Dynamic textures have been modeled as linear dynamic systems by unfolding the video frames into column vectors and describing their trajectory as time evolves. After the projection of the vectors onto a lower dimensional space by a singular value decomposition (SVD), the trajectory is modeled using system identification techniques. Synthesis is obtained by driving the system with random noise. In this paper, we show that the standard SVD can be replaced by a higher order SVD (HOSVD), originally known as Tucker decomposition. HOSVD decomposes the dynamic texture as a multidimensional signal (tensor) without unfolding the video frames on column vectors. This is a more natural and flexible decomposition, since it permits us to perform dimension reduction in the spatial, temporal, and chromatic domain, while standard SVD allows for temporal reduction only. We show that for a comparable synthesis quality, the HOSVD approach requires, on average, five times less parameters than the standard SVD approach. The analysis part is more expensive, but the synthesis has the same cost as existing algorithms. Our technique is, thus, well suited to dynamic texture synthesis on devices limited by memory and computational power, such as PDAs or mobile phones.
Propagation of a higher-order cosh-Gaussian beam in turbulent atmosphere.
Zhou, Guoquan
2011-02-28
The propagation of a higher-order cosh-Gaussian beam through a paraxial and real ABCD optical system in turbulent atmosphere has been investigated. The analytical expressions for the average intensity, the effective beam size, and the kurtosis parameter of a higher-order cosh-Gaussian beam through a paraxial and real ABCD optical system are derived in turbulent atmosphere. The average intensity distribution and the spreading properties of a higher-order cosh-Gaussian in turbulent atmosphere are numerically demonstrated. The influences of the beam parameters and the structure constant of the atmospheric turbulence on the propagation of a higher-order cosh-Gaussian beam in turbulent atmosphere are also examined in detail.
Multiple higher-order stop gaps in infrared polymer photonic crystals.
Straub, M; Ventura, M; Gu, M
2003-07-25
Engineering of stop gaps between higher photonic bands provides an alternative to miniaturization of photonic crystals. Femtosecond laser microfabrication of highly correlated void channel polymer microstructures results in photonic crystals with large stop gaps and a multitude of higher-order gaps in the mid- and near-infrared spectral regions. The gap wavelengths obey Bragg's law. Consistent with theory, varying the woodpile structure unit cell allows for tuning the number of higher-order gaps, and transitions from mere resonant Bragg scattering to stop band total reflection are observed.
Characterization of Imposed Ordered Structures in MDPX
NASA Astrophysics Data System (ADS)
Hall, Taylor; Thomas, Edward; Konopka, Uwe; Merlino, Robert; Rosenberg, Marlene
2016-10-01
It is well understood that the microparticles in complex, or dusty, plasmas will form self-consistent crystalline patterns at the proper plasma parameters. In the Magnetized Dusty Plasma Experiment (MDPX) device, studies have been made of imposed, ordered structuring of the dust particles to a two dimensional grid. At high magnetic field (B >1 Tesla), the dust particles are shown to become spatially oriented to the structure of a wire mesh embedded in an electrically floating, upper electrode while the particles are suspended in a plasma that is generated by the powered, lower electrode in the experiment. With even higher magnetic field (B >2 Tesla), the particles become strongly confined to the mesh pattern with the particles constrained to a quasi-discreet motion that closely follows the mesh pattern. This presentation characterizes the structure of the potential energy well in which the dust particles are trapped through observation of particle motion and measurement of the thermal properties of the particles. This work is supported by funding from the U. S. Department of Energy Grant Number DE - SC0010485 and the NASA/Jet Propulsion Laboratory, JPL-1543114.
A reduced-rank approach for implementing higher-order Volterra filters
NASA Astrophysics Data System (ADS)
O. Batista, Eduardo L.; Seara, Rui
2016-12-01
The use of Volterra filters in practical applications is often limited by their high computational burden. To cope with this problem, many strategies for implementing Volterra filters with reduced complexity have been proposed in the open literature. Some of these strategies are based on reduced-rank approaches obtained by defining a matrix of filter coefficients and applying the singular value decomposition to such a matrix. Then, discarding the smaller singular values, effective reduced-complexity Volterra implementations can be obtained. The application of this type of approach to higher-order Volterra filters (considering orders greater than 2) is however not straightforward, which is especially due to some difficulties encountered in the definition of higher-order coefficient matrices. In this context, the present paper is devoted to the development of a novel reduced-rank approach for implementing higher-order Volterra filters. Such an approach is based on a new form of Volterra kernel implementation that allows decomposing higher-order kernels into structures composed only of second-order kernels. Then, applying the singular value decomposition to the coefficient matrices of these second-order kernels, effective implementations for higher-order Volterra filters can be obtained. Simulation results are presented aiming to assess the effectiveness of the proposed approach.
Signal analysis applications of nonlinear dynamics and higher-order statistics
NASA Astrophysics Data System (ADS)
Solinsky, James C.; Feeney, John J.
1994-03-01
The use of higher-order statistics (HOS) in acoustic, and financial signal analysis applications is outlined in theory and followed with specific data examples. HOS analysis is used to identify data regions of interest, and nonlinear dynamics (ND) analysis is used in a 4D embedded space to show structural density changes resulting from the HOS regions. A second-order statistical comparison is made with the same data processed to have random Fourier phase, since the HOS information is contained in this nonrandom phase. These empirical results indicate that HOS data regions are structural distortions to a second-order planar disk in the 4D ND analysis space.
Degenerate higher order scalar-tensor theories beyond Horndeski up to cubic order
NASA Astrophysics Data System (ADS)
Achour, J. Ben; Crisostomi, M.; Koyama, K.; Langlois, D.; Noui, K.; Tasinato, G.
2016-12-01
We present all scalar-tensor Lagrangians that are cubic in second derivatives of a scalar field, and that are degenerate, hence avoiding Ostrogradsky instabilities. Thanks to the existence of constraints, they propagate no more than three degrees of freedom, despite having higher order equations of motion. We also determine the viable combinations of previously identified quadratic degenerate Lagrangians and the newly established cubic ones. Finally, we study whether the new theories are connected to known scalar-tensor theories such as Horndeski and beyond Horndeski, through conformal or disformal transformations.
Higher-order factors of the Big Five in a multi-informant sample.
DeYoung, Colin G
2006-12-01
In a large community sample (N=490), the Big Five were not orthogonal when modeled as latent variables representing the shared variance of reports from 4 different informants. Additionally, the standard higher-order factor structure was present in latent space: Neuroticism (reversed), Agreeableness, and Conscientiousness formed one factor, labeled Stability, and Extraversion and Openness/Intellect formed a second factor, labeled Plasticity. Comparison of two instruments, the Big Five Inventory and the Mini-Markers, supported the hypotheses that single-adjective rating instruments are likely to yield lower interrater agreement than phrase rating instruments and that lower interrater agreement is associated with weaker correlations among the Big Five and a less coherent higher-order factor structure. In conclusion, an interpretation of the higher-order factors is discussed, including possible neurobiological substrates.
Nonlinear acoustics in higher-order approximation: Comment.
Mitri, Farid G
2010-08-01
Some useful expressions for the second- and third-order equations for harmonic generation of infinite plane acoustic waves in a nonlinear non-viscous fluid are corrected. The concern addressed in the present comment is to point out some typographical errors in the first-order velocity and pressure expressions intervening in the calculation of the secondorder nonlinear equations, as well as a miscalculation of the axial component of the third-order Lighthill tensor term and the resulting third-order velocity and pressure equations presented in that paper.
Performance-Based Task Assessment of Higher-Order Proficiencies in Redesigned STEM High Schools
ERIC Educational Resources Information Center
Ernst, Jeremy V.; Glennie, Elizabeth; Li, Songze
2017-01-01
This study explored student abilities in applying conceptual knowledge when presented with structured performance tasks. Specifically, the study gauged proficiency in higher-order applications of students enrolled in earth and environmental science or biology. The student sample was drawn from a Redesigned STEM high school model where a tested…
Addition of higher order plate and shell elements into NASTRAN computer program
NASA Technical Reports Server (NTRS)
Narayanaswami, R.; Goglia, G. L.
1976-01-01
Two higher order plate elements, the linear strain triangular membrane element and the quintic bending element, along with a shallow shell element, suitable for inclusion into the NASTRAN (NASA Structural Analysis) program are described. Additions to the NASTRAN Theoretical Manual, Users' Manual, Programmers' Manual and the NASTRAN Demonstration Problem Manual, for inclusion of these elements into the NASTRAN program are also presented.
A Matrix Approach for General Higher Order Linear Recurrences
2011-01-01
properties of linear recurrences (such as the well-known Fibonacci and Pell sequences ). In [2], Er defined k linear recurring sequences of order at...the nth term of the ith generalized order-k Fibonacci sequence . Communicated by Lee See Keong. Received: March 26, 2009; Revised: August 28, 2009...6], the author gave the generalized order-k Fibonacci and Pell (F-P) sequence as follows: For m ≥ 0, n > 0 and 1 ≤ i ≤ k uin = 2 muin−1 + u i n−2
Extraction and absorption of higher order modes in room temperature accelerators
Rimmer, R.A.
1993-02-01
This paper describes methods for extracting and absorbing unwanted higher-order modes (HOMs) from normal-conducting accelerator structures. An introduction to the problems caused by HOMs is followed by a brief history of the development of techniques to suppress them, and some examples taken from existing and planned accelerators. These include damped radio frequency (RF) cavities for storage rings such as the proposed PEP-II B factory and accelerating structures for future linear collider projects.
Ordered macromolecular structures in ferrofluid mixtures
Hayter, J.B.; Pynn, R.; Charles, S.; Skjeltorp, A.T.; Trewhella, J.; Stubbs, G.; Timmins, P.
1989-04-03
We have observed ordering of dilute dispersions of spherical and cylindrical macromolecules in magnetized ferrofluids. The order results from structural correlations between macromolecular and ferrofluid particles rather than from macroscopic magnetostatic effects. We have aligned elongated macromolecules by this technique and have obtained anisotropic neutron-diffraction patterns, which reflect the internal structure of the macromolecules. The method provides a tool for orienting suspended macromolecular assemblies which are not amenable to conventional alignment techniques.
Higher-Order Panel Method for Aerodynamic Flow Analysis
NASA Technical Reports Server (NTRS)
Erickson, L.; Carmichael, R. L.; Levin, A. D.; Magnus, A.; Epton, M.; Baruah, P.; Massena, B.; Bussoletti, J.; Sidwell, K.; Johnson, F.; Zeppa, J.; Bates, G.; Clemens, D.; Derbyshire, T.; Purdon, D.; Chiang, D.; Rubbert, P.; Nelson, F.; Wai, J.; Tsurusaki, K.; Smith, N.; Snyder, J. R.; Sotomayer, W.; Dejongh, J.; Thomas, J. L.
1982-01-01
PANAIR uses high-order panel method to predict inviscid subsonic or supersonic flows about arbitrary configuration. Panel method solves linear partial differential equation numerically by approximating configuration surface with panels on which unknown "singularity strengths" are defined. PANAIR includes advanced software technology as well as advanced aerodynamic technology.
Higher-order nonlinear priors for surface reconstruction.
Tasdizen, Tolga; Whitaker, Ross
2004-07-01
For surface reconstruction problems with noisy and incomplete range data, a Bayesian estimation approach can improve the overall quality of the surfaces. The Bayesian approach to surface estimation relies on a likelihood term, which ties the surface estimate to the input data, and the prior, which ensures surface smoothness or continuity. This paper introduces a new high-order, nonlinear prior for surface reconstruction. The proposed prior can smooth complex, noisy surfaces, while preserving sharp, geometric features, and it is a natural generalization of edge-preserving methods in image processing, such as anisotropic diffusion. An exact solution would require solving a fourth-order partial differential equation (PDE), which can be difficult with conventional numerical techniques. Our approach is to solve a cascade system of two second-order PDEs, which resembles the original fourth-order system. This strategy is based on the observation that the generalization of image processing to surfaces entails filtering the surface normals. We solve one PDE for processing the normals and one for refitting the surface to the normals. Furthermore, we implement the associated surface deformations using level sets. Hence, the algorithm can accommodate very complex shapes with arbitrary and changing topologies. This paper gives the mathematical formulation and describes the numerical algorithms. We also show results using range and medical data.
Higher Order Thinking Skills for Students with Special Needs.
ERIC Educational Resources Information Center
Savage, Louise; Lombardi, Thomas P.
1993-01-01
This article describes methods for teaching higher level thinking skills to children. A four-step teaching plan utilizing Beyer's Taxonomy of thinking skills provides a sequential technique for teaching these skills as do increased verbal interaction, skillful questioning, and use of knowledge organizers. The I PLAN strategy can aid decision…
Response spectrum method for extreme wave loading with higher order components of drag force
NASA Astrophysics Data System (ADS)
Reza, Tabeshpour Mohammad; Mani, Fatemi Dezfouli; Ali, Dastan Diznab Mohammad; Saied, Mohajernasab; Saied, Seif Mohammad
2017-03-01
Response spectra of fixed offshore structures impacted by extreme waves are investigated based on the higher order components of the nonlinear drag force. In this way, steel jacket platforms are simplified as a mass attached to a light cantilever cylinder and their corresponding deformation response spectra are estimated by utilizing a generalized single degree of freedom system. Based on the wave data recorded in the Persian Gulf region, extreme wave loading conditions corresponding to different return periods are exerted on the offshore structures. Accordingly, the effect of the higher order components of the drag force is considered and compared to the linearized state for different sea surface levels. When the fundamental period of the offshore structure is about one third of the main period of wave loading, the results indicate the linearized drag term is not capable of achieving a reliable deformation response spectrum.
Response spectrum method for extreme wave loading with higher order components of drag force
NASA Astrophysics Data System (ADS)
Reza, Tabeshpour Mohammad; Mani, Fatemi Dezfouli; Mohammad Ali, Dastan Diznab; Saied, Mohajernasab; Saied, Seif Mohammad
2017-01-01
Response spectra of fixed offshore structures impacted by extreme waves are investigated based on the higher order components of the nonlinear drag force. In this way, steel jacket platforms are simplified as a mass attached to a light cantilever cylinder and their corresponding deformation response spectra are estimated by utilizing a generalized single degree of freedom system. Based on the wave data recorded in the Persian Gulf region, extreme wave loading conditions corresponding to different return periods are exerted on the offshore structures. Accordingly, the effect of the higher order components of the drag force is considered and compared to the linearized state for different sea surface levels. When the fundamental period of the offshore structure is about one third of the main period of wave loading, the results indicate the linearized drag term is not capable of achieving a reliable deformation response spectrum.
Structural order and disorder in Precambrian kerogens
Buseck, P.R.; Bo-Jun, H.; Miner, B.
1988-01-01
High-resolution transmission electron microscopy (HRTEM) has been used to examine the structures of a wide range of Precambrian kerogens from rocks with ages between 0.9 and 3.8 billion years. The authors find recognizable structural ordering in samples that show little or no evidence of crystallinity by powder X-ray diffraction measurements. A wide range in degree of ordering is evident in the HRTEM images. A rough correlation exists between the ordering displayed in the HRTEM images and both the sample ages and their H/C ratios. Many kerogen samples are structurally heterogeneous, possibly reflecting a variety of precursors, and source regions. The observed structural heterogeneities probably extend to other parameters; when isotopic and X-ray measurements can be made on the same scale as HRTEM images, similar scatter presumably will also be evident.
Machine learning using a higher order correlation network
Lee, Y.C.; Doolen, G.; Chen, H.H.; Sun, G.Z.; Maxwell, T.; Lee, H.Y.
1986-01-01
A high-order correlation tensor formalism for neural networks is described. The model can simulate auto associative, heteroassociative, as well as multiassociative memory. For the autoassociative model, simulation results show a drastic increase in the memory capacity and speed over that of the standard Hopfield-like correlation matrix methods. The possibility of using multiassociative memory for a learning universal inference network is also discussed. 9 refs., 5 figs.
The period functionsʼ higher order derivatives
NASA Astrophysics Data System (ADS)
Sabatini, M.
We prove a formula for the n-th derivative of the period function T in a period annulus of a planar differential system. For n=1, we obtain Freire, Gasull and Guillamon formula for the period's first derivative (Chicone and Dumortier, 1993) [17]. We apply such a result to Hamiltonian systems with separable variables and other systems. We give some sufficient conditions for the period function of conservative second order ODE's to be convex.
Higher-order numerical solutions using cubic splines
NASA Technical Reports Server (NTRS)
Rubin, S. G.; Khosla, P. K.
1976-01-01
A cubic spline collocation procedure was developed for the numerical solution of partial differential equations. This spline procedure is reformulated so that the accuracy of the second-derivative approximation is improved and parallels that previously obtained for lower derivative terms. The final result is a numerical procedure having overall third-order accuracy of a nonuniform mesh. Solutions using both spline procedures, as well as three-point finite difference methods, are presented for several model problems.
Multilevel Higher-Order Item Response Theory Models
ERIC Educational Resources Information Center
Huang, Hung-Yu; Wang, Wen-Chung
2014-01-01
In the social sciences, latent traits often have a hierarchical structure, and data can be sampled from multiple levels. Both hierarchical latent traits and multilevel data can occur simultaneously. In this study, we developed a general class of item response theory models to accommodate both hierarchical latent traits and multilevel data. The…
Higher-order Hamiltonian fluid reduction of Vlasov equation
Perin, M.; Chandre, C.; Morrison, P.J.; Tassi, E.
2014-09-15
From the Hamiltonian structure of the Vlasov equation, we build a Hamiltonian model for the first three moments of the Vlasov distribution function, namely, the density, the momentum density and the specific internal energy. We derive the Poisson bracket of this model from the Poisson bracket of the Vlasov equation, and we discuss the associated Casimir invariants.
Higher-Order Theory for Functionally Graded Materials
NASA Technical Reports Server (NTRS)
Aboudi, J.; Pindera, M. J.; Arnold, Steven M.
2001-01-01
Functionally graded materials (FGM's) are a new generation of engineered materials wherein the microstructural details are spatially varied through nonuniform distribution of the reinforcement phase(s). Engineers accomplish this by using reinforcements with different properties, sizes, and shapes, as well as by interchanging the roles of the reinforcement and matrix phases in a continuous manner (ref. 1). The result is a microstructure that produces continuously or discretely changing thermal and mechanical properties at the macroscopic or continuum scale. This new concept of engineering the material's microstructure marks the beginning of a revolution both in the materials science and mechanics of materials areas since it allows one, for the first time, to fully integrate the material and structural considerations into the final design of structural components. Functionally graded materials are ideal candidates for applications involving severe thermal gradients, ranging from thermal structures in advanced aircraft and aerospace engines to computer circuit boards. Owing to the many variables that control the design of functionally graded microstructures, full exploitation of the FGM's potential requires the development of appropriate modeling strategies for their response to combined thermomechanical loads. Previously, most computational strategies for the response of FGM's did not explicitly couple the material's heterogeneous microstructure with the structural global analysis. Rather, local effective or macroscopic properties at a given point within the FGM were first obtained through homogenization based on a chosen micromechanics scheme and then subsequently used in a global thermomechanical analysis.
Higher-order symplectic Born-Oppenheimer molecular dynamics
Niklasson, Anders; Bock, Nicolas; Challacombe, Matt; Odell, Anders; Delin, Anna; Johansson, Borje
2009-01-01
The extended Lagrangian formulation of time-reversible Born-Oppenheimer molecular dynamics (TR-BOMD) enables the use of geometric integrators in the propagation of both the nuclear and the electronic degrees of freedom on the Born-Oppenheimer potential energy surface. Different symplectic integrators up to the 6th order have been adapted and optimized to TR-BOMD in the framework of ab initio self-consistent-field theory. It is shown how the accuracy can be significantly improved compared to a conventional Verlet integration at the same level of computational cost, in particular for the case of very high accuracy requirements.
A higher-order upwind method for viscoelastic flow
NASA Astrophysics Data System (ADS)
Nonaka, Andrew Jeffrey Tadao
A conservative finite difference method designed to capture elastic wave propagation in viscoelastic fluids in two space dimensions is presented. The governing equations are the incompressible Navier-Stokes equations coupled to the Oldroyd-B constitutive equations for viscoelastic stress. The equations are cast into a hybrid conservation form to make use of a second-order upwind method to treat the hyperbolic part of the equations. The hyperbolic step also utilizes a new exact and efficient Riemann solver. A numerical stress splitting technique provides a well-posed discretization for the entire range of Newtonian and elastic fluids. Incompressibility is enforced through both a projection method and a special partitioning of variables which suppresses compressive waves in the hyperbolic step. An embedded boundary approach for irregular geometry is employed, in which regular Cartesian cells are cut into irregular control volumes, requiring special discretization stencils. The resulting method is second-order accurate in L1 for smooth geometries for a range of Oldroyd-B fluids.
Higher-order hybrid stress triangular Mindlin plate element
NASA Astrophysics Data System (ADS)
Li, Tan; Ma, Xu; Xili, Jing; Chen, Wanji
2016-12-01
A 6-node triangular hybrid stress element is presented for Mindlin plate in this paper. The proposed element, denoted by TH6-27β, can pass both the zero shear stress patch test and the non-zero constant shear stress enhanced patch test and, it can be employed to analyze very thin plate. To accomplish this purpose, special attention is devoted to selecting boundary displacement interpolation and stress approximation in domain. The arbitrary order Timoshenko beam function is used successfully to derive the displacement interpolation along each side of the element. According to the equilibrium equations, an appropriate stress approximation is rationally obtained. The assumed stress field is modified by using 27β instead of 15β to improve the accuracy. Numerical results show that the element is free of shear locking, and reliable for thick and thin plates. Moreover, it has no spurious zero energy modes and with geometric invariance (coordinate invariance, node sequencing independence).
A proposed ringing analysis model for higher order tether response
Natvig, B.J.
1994-12-31
The problem of high-frequency transient responses of Tension Leg Platforms, TLPs, under certain severe sea situations has been known for some time. Until recently, it was not known that this type of loading and response mechanism could produce tether loads of critical importance to the structural integrity of such structures. Presently, there is considerable ongoing discussion as to what causes tether ringing. NPD (1992) assembled a document where the views of the Norwegian Shelf operators and one Norwegian engineering company were summarized. At present there seems to be consensus that ringing, at least to a large extent, is caused by nonlinearities in the free surface variable wetting region of the TLP. Ringing is not predicted by linearized frequency domain analysis methods. There are a number of variable wetting contributions. Some of these are fairly obvious while others are less straight forward. A number of the contributions, of purely theoretical or engineering nature, identified to date are discussed in this paper. Based on this an intuitive method for ringing analysis is presented.
Higher-order adaptive finite-element methods for Kohn–Sham density functional theory
Motamarri, P.; Nowak, M.R.; Leiter, K.; Knap, J.; Gavini, V.
2013-11-15
We present an efficient computational approach to perform real-space electronic structure calculations using an adaptive higher-order finite-element discretization of Kohn–Sham density-functional theory (DFT). To this end, we develop an a priori mesh-adaption technique to construct a close to optimal finite-element discretization of the problem. We further propose an efficient solution strategy for solving the discrete eigenvalue problem by using spectral finite-elements in conjunction with Gauss–Lobatto quadrature, and a Chebyshev acceleration technique for computing the occupied eigenspace. The proposed approach has been observed to provide a staggering 100–200-fold computational advantage over the solution of a generalized eigenvalue problem. Using the proposed solution procedure, we investigate the computational efficiency afforded by higher-order finite-element discretizations of the Kohn–Sham DFT problem. Our studies suggest that staggering computational savings—of the order of 1000-fold—relative to linear finite-elements can be realized, for both all-electron and local pseudopotential calculations, by using higher-order finite-element discretizations. On all the benchmark systems studied, we observe diminishing returns in computational savings beyond the sixth-order for accuracies commensurate with chemical accuracy, suggesting that the hexic spectral-element may be an optimal choice for the finite-element discretization of the Kohn–Sham DFT problem. A comparative study of the computational efficiency of the proposed higher-order finite-element discretizations suggests that the performance of finite-element basis is competing with the plane-wave discretization for non-periodic local pseudopotential calculations, and compares to the Gaussian basis for all-electron calculations to within an order of magnitude. Further, we demonstrate the capability of the proposed approach to compute the electronic structure of a metallic system containing 1688
Higher-order adaptive finite-element methods for Kohn-Sham density functional theory
NASA Astrophysics Data System (ADS)
Motamarri, P.; Nowak, M. R.; Leiter, K.; Knap, J.; Gavini, V.
2013-11-01
We present an efficient computational approach to perform real-space electronic structure calculations using an adaptive higher-order finite-element discretization of Kohn-Sham density-functional theory (DFT). To this end, we develop an a priori mesh-adaption technique to construct a close to optimal finite-element discretization of the problem. We further propose an efficient solution strategy for solving the discrete eigenvalue problem by using spectral finite-elements in conjunction with Gauss-Lobatto quadrature, and a Chebyshev acceleration technique for computing the occupied eigenspace. The proposed approach has been observed to provide a staggering 100-200-fold computational advantage over the solution of a generalized eigenvalue problem. Using the proposed solution procedure, we investigate the computational efficiency afforded by higher-order finite-element discretizations of the Kohn-Sham DFT problem. Our studies suggest that staggering computational savings-of the order of 1000-fold-relative to linear finite-elements can be realized, for both all-electron and local pseudopotential calculations, by using higher-order finite-element discretizations. On all the benchmark systems studied, we observe diminishing returns in computational savings beyond the sixth-order for accuracies commensurate with chemical accuracy, suggesting that the hexic spectral-element may be an optimal choice for the finite-element discretization of the Kohn-Sham DFT problem. A comparative study of the computational efficiency of the proposed higher-order finite-element discretizations suggests that the performance of finite-element basis is competing with the plane-wave discretization for non-periodic local pseudopotential calculations, and compares to the Gaussian basis for all-electron calculations to within an order of magnitude. Further, we demonstrate the capability of the proposed approach to compute the electronic structure of a metallic system containing 1688 atoms using
Higher order vortex gyrotropic modes in circular ferromagnetic nanodots.
Ding, Junjia; Kakazei, Gleb N; Liu, Xinming; Guslienko, Konstantin Y; Adeyeye, Adekunle O
2014-04-25
Magnetic vortex that consists of an in-plane curling magnetization configuration and a needle-like core region with out-of-plane magnetization is known to be the ground state of geometrically confined submicron soft magnetic elements. Here magnetodynamics of relatively thick (50-100 nm) circular Ni80Fe20 dots were probed by broadband ferromagnetic resonance in the absence of external magnetic field. Spin excitation modes related to the thickness dependent vortex core gyrotropic dynamics were detected experimentally in the gigahertz frequency range. Both analytical theory and micromagnetic simulations revealed that these exchange dominated modes are flexure oscillations of the vortex core string with n = 0,1,2 nodes along the dot thickness. The intensity of the mode with n = 1 depends significantly on both dot thickness and diameter and in some cases is higher than the one of the uniform mode with n = 0. This opens promising perspectives in the area of spin transfer torque oscillators.
Higher order vortex gyrotropic modes in circular ferromagnetic nanodots
Ding, Junjia; Kakazei, Gleb N.; Liu, Xinming; Guslienko, Konstantin Y.; Adeyeye, Adekunle O.
2014-01-01
Magnetic vortex that consists of an in-plane curling magnetization configuration and a needle-like core region with out-of-plane magnetization is known to be the ground state of geometrically confined submicron soft magnetic elements. Here magnetodynamics of relatively thick (50–100 nm) circular Ni80Fe20 dots were probed by broadband ferromagnetic resonance in the absence of external magnetic field. Spin excitation modes related to the thickness dependent vortex core gyrotropic dynamics were detected experimentally in the gigahertz frequency range. Both analytical theory and micromagnetic simulations revealed that these exchange dominated modes are flexure oscillations of the vortex core string with n = 0,1,2 nodes along the dot thickness. The intensity of the mode with n = 1 depends significantly on both dot thickness and diameter and in some cases is higher than the one of the uniform mode with n = 0. This opens promising perspectives in the area of spin transfer torque oscillators. PMID:24762659
Improvements to local projective noise reduction through higher order and multiscale refinements
NASA Astrophysics Data System (ADS)
Moore, Jack Murdoch; Small, Michael; Karrech, Ali
2015-06-01
The broad spectrum characteristic of signals from nonlinear systems obstructs noise reduction techniques developed for linear systems. Local projection was developed to reduce noise while preserving nonlinear deterministic structures, and a second order refinement to local projection which was proposed ten years ago does so particularly effectively. It involves adjusting the origin of the projection subspace to better accommodate the geometry of the attractor. This paper describes an analytic motivation for the enhancement from which follows further higher order and multiple scale refinements. However, the established enhancement is frequently as or more effective than the new filters arising from solely geometric considerations. Investigation of the way that measurement errors reinforce or cancel throughout the refined local projection procedure explains the special efficacy of the existing enhancement, and leads to a new second order refinement offering widespread gains. Different local projective filters are found to be best suited to different noise levels. At low noise levels, the optimal order increases as noise increases. At intermediate levels second order tends to be optimal, while at high noise levels prototypical local projection is most effective. The new higher order filters perform better relative to established filters for longer signals or signals corresponding to higher dimensional attractors.
NASA Technical Reports Server (NTRS)
Graves, R. A., Jr.
1975-01-01
The previously obtained second-order-accurate partial implicitization numerical technique used in the solution of fluid dynamic problems was modified with little complication to achieve fourth-order accuracy. The Von Neumann stability analysis demonstrated the unconditional linear stability of the technique. The order of the truncation error was deduced from the Taylor series expansions of the linearized difference equations and was verified by numerical solutions to Burger's equation. For comparison, results were also obtained for Burger's equation using a second-order-accurate partial-implicitization scheme, as well as the fourth-order scheme of Kreiss.
Higher-harmonic collective modes in a trapped gas from second-order hydrodynamics
NASA Astrophysics Data System (ADS)
Lewis, W. E.; Romatschke, P.
2017-02-01
Utilizing a second-order hydrodynamics formalism, the dispersion relations for the frequencies and damping rates of collective oscillations as well as spatial structure of these modes up to the decapole oscillation in both two- and three- dimensional gas geometries are calculated. In addition to higher-order modes, the formalism also gives rise to purely damped ‘non-hydrodynamic’ modes. We calculate the amplitude of the various modes for both symmetric and asymmetric trap quenches, finding excellent agreement with an exact quantum mechanical calculation. We find that higher-order hydrodynamic modes are more sensitive to the value of shear viscosity, which may be of interest for the precision extraction of transport coefficients in Fermi gas systems.
Higher-Order Corrections to Earthʼs Ionosphere Shocks
NASA Astrophysics Data System (ADS)
Abdelwahed, H. G.; El-Shewy, E. K.
2017-01-01
Nonlinear shock wave structures in unmagnetized collisionless viscous plasmas composed fluid of positive (negative) ions and nonthermally electron distribution are examined. For ion shock formation, a reductive perturbation technique applied to derive Burgers equation for lowest-order potential. As the shock amplitude decreasing or enlarging, its steepness and velocity deviate from Burger equation. Burgers type equation with higher order dissipation must be obtained to avoid this deviation. Solution for the compined two equations has been derived using renormalization analysis. Effects of higher-order, positive- negative mass ratio Q, electron nonthermal parameter δ and kinematic viscosities coefficient of positive (negative) ions {η }1 and {η }2 on the electrostatic shocks in Earth’s ionosphere are also argued. Supported by the Deanship of Scientific Research at Prince Sattam Bin Abdulaziz University under the Research Project No. 2015/01/4787
Interaction of Higher Order Modes Cluster (HOMC) guided waves with notch-like defects in plates
NASA Astrophysics Data System (ADS)
Sri Harsha Reddy, K.; Rajagopal, Prabhu; Balasubramaniam, Krishnan; Hill, Samuel; Dixon, Steve
2017-02-01
Guided ultrasonic waves are widely used for long range inspection. Higher Order Modes Cluster (HOMC), discovered at the author's research group [1-3] consist of multiple higher order guided wave modes that travel together as a single wave-packet and without appreciable dispersion for distances in the range of meters. These waves not only propagate along the length of the structure but also cover the entire thickness, and in view of the higher frequencies, they can offer improved resolution over conventional low-frequency guided waves. This paper studies the sensitivity of axial plate HOMC to notch-like defects, evaluated by calculating wave reflection co-efficient. The studies are carried out using finite element models validated by experiments. Analysis is presented for better understanding of wave-defect interaction. Advantages and limitations for practical realization of the above approach are also discussed.
Higher-order assembly of collagen peptides into nano- and microscale materials.
Przybyla, David E; Chmielewski, Jean
2010-06-01
The triple-helical structure of collagen peptides has recently been harnessed as a subunit in the higher-order assembly of unique biomaterials. Specific assembly signals have been designed within collagen peptides, including hydrophobic groups, electrostatic interactions, and metal-ligand binding, to name a few. In this way, a range of novel assemblies have been obtained, including nano- to microscale fibers, gels, spheres, and meshes, each with the potential for novel biological applications in drug delivery, tissue engineering, and regenerative medicine.
Higher-Order, Space-Time Adaptive Finite Volume Methods: Algorithms, Analysis and Applications
Minion, Michael
2014-04-29
The four main goals outlined in the proposal for this project were: 1. Investigate the use of higher-order (in space and time) finite-volume methods for fluid flow problems. 2. Explore the embedding of iterative temporal methods within traditional block-structured AMR algorithms. 3. Develop parallel in time methods for ODEs and PDEs. 4. Work collaboratively with the Center for Computational Sciences and Engineering (CCSE) at Lawrence Berkeley National Lab towards incorporating new algorithms within existing DOE application codes.
Collapse of higher-order solute concentration moments in groundwater transport
NASA Astrophysics Data System (ADS)
Srzic, Veljko; Andricevic, Roko; Gotovac, Hrvoje; Cvetkovic, Vladimir
2013-08-01
In this paper, we use numerical simulations based on a Lagrangian framework to study contaminant transport through highly heterogeneous porous media due to advection and local diffusion (under local diffusion, we assume coupled effect of mechanical dispersion and molecular diffusion). The analysis of the concentration field is done for the case of a two-dimensional hydraulic conductivity domain representing the aquifer, with three log-conductivity structures that differ in spatial correlation. In addition to different conductivity structures, we focus our investigation on mild and highly heterogeneous porous media characterized by the values of hydraulic log-conductivity variance >(σY2>) being equal to 1 and 8. In the concentration moment analysis, we show that a linear relationship exists between higher-order to second-order normalized concentration moments on a log-log scale up to the fourth-order moment. This leads to the important finding that moments of a higher than the second order can be derived based on information about the first two concentration moments only. Such a property has been observed previously for boundary-layer water channels, wind tunnels, and turbulent diffusion in open terrain and laboratory experiments. Normalized moments are shown to collapse for different types of hydraulic conductivity structures, Peclet (Pe) numbers and σY2 values. In the case of local diffusion absence, a linear log-log relationship is derived analytically and is set as a lower limit. The deviation from the lower limit is explained to be predominantly caused by the local diffusion, which needs time to evolve. In the case of local diffusion presence, we define the moment deriving function (MDF) to describe the linear log-log relationship between higher-order concentration moments to the second-order normalized one. Finally, the comparison between numerical results and those obtained from the Columbus Air Force Base Macrodispersion Experiment (MADE 1) is used to
Radiation Heat Transfer Between Diffuse-Gray Surfaces Using Higher Order Finite Elements
NASA Technical Reports Server (NTRS)
Gould, Dana C.
2000-01-01
This paper presents recent work on developing methods for analyzing radiation heat transfer between diffuse-gray surfaces using p-version finite elements. The work was motivated by a thermal analysis of a High Speed Civil Transport (HSCT) wing structure which showed the importance of radiation heat transfer throughout the structure. The analysis also showed that refining the finite element mesh to accurately capture the temperature distribution on the internal structure led to very large meshes with unacceptably long execution times. Traditional methods for calculating surface-to-surface radiation are based on assumptions that are not appropriate for p-version finite elements. Two methods for determining internal radiation heat transfer are developed for one and two-dimensional p-version finite elements. In the first method, higher-order elements are divided into a number of sub-elements. Traditional methods are used to determine radiation heat flux along each sub-element and then mapped back to the parent element. In the second method, the radiation heat transfer equations are numerically integrated over the higher-order element. Comparisons with analytical solutions show that the integration scheme is generally more accurate than the sub-element method. Comparison to results from traditional finite elements shows that significant reduction in the number of elements in the mesh is possible using higher-order (p-version) finite elements.
A Higher-Order Neural Network Design for Improving Segmentation Performance in Medical Image Series
NASA Astrophysics Data System (ADS)
Selvi, Eşref; Selver, M. Alper; Güzeliş, Cüneyt; Dicle, Oǧuz
2014-03-01
Segmentation of anatomical structures from medical image series is an ongoing field of research. Although, organs of interest are three-dimensional in nature, slice-by-slice approaches are widely used in clinical applications because of their ease of integration with the current manual segmentation scheme. To be able to use slice-by-slice techniques effectively, adjacent slice information, which represents likelihood of a region to be the structure of interest, plays critical role. Recent studies focus on using distance transform directly as a feature or to increase the feature values at the vicinity of the search area. This study presents a novel approach by constructing a higher order neural network, the input layer of which receives features together with their multiplications with the distance transform. This allows higher-order interactions between features through the non-linearity introduced by the multiplication. The application of the proposed method to 9 CT datasets for segmentation of the liver shows higher performance than well-known higher order classification neural networks.
NASA Astrophysics Data System (ADS)
Lim, C. W.; Zhang, G.; Reddy, J. N.
2015-05-01
In recent years there have been many papers that considered the effects of material length scales in the study of mechanics of solids at micro- and/or nano-scales. There are a number of approaches and, among them, one set of papers deals with Eringen's differential nonlocal model and another deals with the strain gradient theories. The modified couple stress theory, which also accounts for a material length scale, is a form of a strain gradient theory. The large body of literature that has come into existence in the last several years has created significant confusion among researchers about the length scales that these various theories contain. The present paper has the objective of establishing the fact that the length scales present in nonlocal elasticity and strain gradient theory describe two entirely different physical characteristics of materials and structures at nanoscale. By using two principle kernel functions, the paper further presents a theory with application examples which relates the classical nonlocal elasticity and strain gradient theory and it results in a higher-order nonlocal strain gradient theory. In this theory, a higher-order nonlocal strain gradient elasticity system which considers higher-order stress gradients and strain gradient nonlocality is proposed. It is based on the nonlocal effects of the strain field and first gradient strain field. This theory intends to generalize the classical nonlocal elasticity theory by introducing a higher-order strain tensor with nonlocality into the stored energy function. The theory is distinctive because the classical nonlocal stress theory does not include nonlocality of higher-order stresses while the common strain gradient theory only considers local higher-order strain gradients without nonlocal effects in a global sense. By establishing the constitutive relation within the thermodynamic framework, the governing equations of equilibrium and all boundary conditions are derived via the variational
In Vivo Generalized Diffusion Tensor Imaging (GDTI) Using Higher-Order Tensors (HOT)
Liu, Chunlei; Mang, Sarah C.; Moseley, Michael E.
2009-01-01
Generalized diffusion tensor imaging (GDTI) using higher order tensor statistics (HOT) generalizes the technique of diffusion tensor imaging (DTI) by including the effect of non-Gaussian diffusion on the signal of magnetic resonance imaging (MRI). In GDTI-HOT, the effect of non-Gaussian diffusion is characterized by higher order tensor statistics (i.e. the cumulant tensors or the moment tensors) such as the covariance matrix (the second-order cumulant tensor), the skewness tensor (the third-order cumulant tensor) and the kurtosis tensor (the fourth-order cumulant tensor) etc. Previously, Monte Carlo simulations have been applied to verify the validity of this technique in reconstructing complicated fiber structures. However, no in vivo implementation of GDTI-HOT has been reported. The primary goal of this study is to establish GDTI-HOT as a feasible in vivo technique for imaging non-Gaussian diffusion. We show that probability distribution function (PDF) of the molecular diffusion process can be measured in vivo with GDTI-HOT and be visualized with 3D glyphs. By comparing GDTI-HOT to fiber structures that are revealed by the highest resolution DWI possible in vivo, we show that the GDTI-HOT can accurately predict multiple fiber orientations within one white matter voxel. Furthermore, through bootstrap analysis we demonstrate that in vivo measurement of HOT elements is reproducible with a small statistical variation that is similar to that of DTI. PMID:19953513
Generalized Flows for Optimal Inference in Higher Order MRF-MAP.
Arora, Chetan; Banerjee, Subhashis; Kalra, Prem Kumar; Maheshwari, S N
2015-07-01
Use of higher order clique potentials in MRF-MAP problems has been limited primarily because of the inefficiencies of the existing algorithmic schemes. We propose a new combinatorial algorithm for computing optimal solutions to 2 label MRF-MAP problems with higher order clique potentials. The algorithm runs in time O(2(k)n(3)) in the worst case (k is size of clique and n is the number of pixels). A special gadget is introduced to model flows in a higher order clique and a technique for building a flow graph is specified. Based on the primal dual structure of the optimization problem, the notions of the capacity of an edge and a cut are generalized to define a flow problem. We show that in this flow graph, when the clique potentials are submodular, the max flow is equal to the min cut, which also is the optimal solution to the problem. We show experimentally that our algorithm provides significantly better solutions in practice and is hundreds of times faster than solution schemes like Dual Decomposition [1], TRWS [2] and Reduction [3], [4], [5]. The framework represents a significant advance in handling higher order problems making optimal inference practical for medium sized cliques.
Excitation of higher order modes in optical fibers with parabolic index profile.
Chen, C L
1988-06-01
A large number of modes can be supported by multimode fibers. There are applications where higher order modes are preferred. Microbend intensity sensors are good examples. The sensitivity of these sensors is greatly increased if higher order modes are excited. In this work, a simple method to excite higher order modes preferentially is suggested. It consists of thin-film gratings deposited directly onto the fiber end. By controlling the film thickness or transparency of the grating structure, a desired transmission coefficient T(r,Phi) is synthesized. The desired mode can be excited preferentially by incident Gaussian beams without the aid of additional optical components. Binary intensity and binary phase gratings have been studied. Numerical investigation reveals that the phase gratings are more effective for the preferential excitation of higher order modes than the intensity gratings. In fact, by using binary phase gratings and in optimal excitation conditions as much as 81.1, 76.9, 74.6, 73.3, and 72.3% of the power in the incoming, linearly polarized, fundamental Gaussian beam can be converted to LP(02), LP(03), LP(04), LP(05), and LP(06) modes, respectively, excluding Fresnel loss.
Slat Noise Predictions Using Higher-Order Finite-Difference Methods on Overset Grids
NASA Technical Reports Server (NTRS)
Housman, Jeffrey A.; Kiris, Cetin
2016-01-01
Computational aeroacoustic simulations using the structured overset grid approach and higher-order finite difference methods within the Launch Ascent and Vehicle Aerodynamics (LAVA) solver framework are presented for slat noise predictions. The simulations are part of a collaborative study comparing noise generation mechanisms between a conventional slat and a Krueger leading edge flap. Simulation results are compared with experimental data acquired during an aeroacoustic test in the NASA Langley Quiet Flow Facility. Details of the structured overset grid, numerical discretization, and turbulence model are provided.
An expansion formula with higher-order derivatives for fractional operators of variable order.
Almeida, Ricardo; Torres, Delfim F M
2013-01-01
We obtain approximation formulas for fractional integrals and derivatives of Riemann-Liouville and Marchaud types with a variable fractional order. The approximations involve integer-order derivatives only. An estimation for the error is given. The efficiency of the approximation method is illustrated with examples. As applications, we show how the obtained results are useful to solve differential equations, and problems of the calculus of variations that depend on fractional derivatives of Marchaud type.
An Expansion Formula with Higher-Order Derivatives for Fractional Operators of Variable Order
Almeida, Ricardo
2013-01-01
We obtain approximation formulas for fractional integrals and derivatives of Riemann-Liouville and Marchaud types with a variable fractional order. The approximations involve integer-order derivatives only. An estimation for the error is given. The efficiency of the approximation method is illustrated with examples. As applications, we show how the obtained results are useful to solve differential equations, and problems of the calculus of variations that depend on fractional derivatives of Marchaud type. PMID:24319382
Electroweak higher-order effects and theoretical uncertainties in deep-inelastic neutrino scattering
Diener, K.-P.O.; Dittmaier, S.; Hollik, W.
2005-11-01
A previous calculation of electroweak O({alpha}) corrections to deep-inelastic neutrino scattering, as e.g. measured by NuTeV and NOMAD, is supplemented by higher-order effects. In detail, we take into account universal two-loop effects from {delta}{alpha} and {delta}{rho} as well as higher-order final-state photon radiation off muons in the structure function approach. Moreover, we make use of the recently released O({alpha})-improved parton distributions MRST2004QED and identify the relevant QED factorization scheme, which is DIS-like. As a technical by-product, we describe slicing and subtraction techniques for an efficient calculation of a new type of real corrections that are induced by the generated photon distribution. A numerical discussion of the higher-order effects suggests that the remaining theoretical uncertainty from unknown electroweak corrections is dominated by nonuniversal two-loop effects and is of the order 0.0003 when translated into a shift in sin{sup 2}{theta}{sub W}=1-M{sub W}{sup 2}/M{sub Z}{sup 2}. The O({alpha}) corrections implicitly included in the parton distributions lead to a shift of about 0.0004.
Assessing School Work Culture: A Higher-Order Analysis and Strategy.
ERIC Educational Resources Information Center
Johnson, William L.; Johnson, Annabel M.; Zimmerman, Kurt J.
This paper reviews a work culture productivity model and reports the development of a work culture instrument based on the culture productivity model. Higher order principal components analysis was used to assess work culture, and a third-order factor analysis shows how the first-order factors group into higher-order factors. The school work…
Proofreading of DNA polymerase: a new kinetic model with higher-order terminal effects
NASA Astrophysics Data System (ADS)
Song, Yong-Shun; Shu, Yao-Gen; Zhou, Xin; Ou-Yang, Zhong-Can; Li, Ming
2017-01-01
The fidelity of DNA replication by DNA polymerase (DNAP) has long been an important issue in biology. While numerous experiments have revealed details of the molecular structure and working mechanism of DNAP which consists of both a polymerase site and an exonuclease (proofreading) site, there were quite a few theoretical studies on the fidelity issue. The first model which explicitly considered both sites was proposed in the 1970s and the basic idea was widely accepted by later models. However, all these models did not systematically investigate the dominant factor on DNAP fidelity, i.e. the higher-order terminal effects through which the polymerization pathway and the proofreading pathway coordinate to achieve high fidelity. In this paper, we propose a new and comprehensive kinetic model of DNAP based on some recent experimental observations, which includes previous models as special cases. We present a rigorous and unified treatment of the corresponding steady-state kinetic equations of any-order terminal effects, and derive analytical expressions for fidelity in terms of kinetic parameters under bio-relevant conditions. These expressions offer new insights on how the higher-order terminal effects contribute substantially to the fidelity in an order-by-order way, and also show that the polymerization-and-proofreading mechanism is dominated only by very few key parameters. We then apply these results to calculate the fidelity of some real DNAPs, which are in good agreements with previous intuitive estimates given by experimentalists.
Suppression of Higher Order Modes in an Array of Cavities Using Waveguides
NASA Astrophysics Data System (ADS)
Shashkov, Ya. V.; Sobenin, N. P.; Bazyl, D. S.; Kaminskiy, V. I.; Mitrofanov, A. A.; Zobov, M. M.
An application of additional harmonic cavities operating at multiplies of the main RF system frequency of 400 MHz is currently under discussionin the framework of the High Luminosity LHC upgrade program [1,2]. A structure consisting of two 800 MHz single cell superconducting cavities with grooved beam pipes coupled by drift tubes has been suggested for implementation. However, it is desirable to increase the number of single cells installed in one cryomodule in order to decrease the number of transitions between "warm" and "cold" parts of the collider vacuum chamber. Unfortunately, it can lead to the appearance of higher order modes (HOM) trapped between the cavities. In order to solve this problem the methods of HOM damping with rectangular waveguides connected to the drift tubes were investigated and compared. We describe the results obtained for arrays of 2, 4 and 8 cavitiesin this paper.
Lin, Ju; Li, Jie; Li, Xiaolei; Wang, Ning
2016-10-01
An acoustic reciprocity theorem is generalized, for a smoothly varying perturbed medium, to a hierarchy of reciprocity theorems including higher-order derivatives of acoustic fields. The standard reciprocity theorem is the first member of the hierarchy. It is shown that the conservation of higher-order interaction quantities is related closely to higher-order derivative distributions of perturbed media. Then integral reciprocity theorems are obtained by applying Gauss's divergence theorem, which give explicit integral representations connecting higher-order interactions and higher-order derivative distributions of perturbed media. Some possible applications to an inverse problem are also discussed.
Efficient Reformulation of the Thermoelastic Higher-order Theory for Fgms
NASA Technical Reports Server (NTRS)
Bansal, Yogesh; Pindera, Marek-Jerzy; Arnold, Steven M. (Technical Monitor)
2002-01-01
Functionally graded materials (FGMs) are characterized by spatially variable microstructures which are introduced to satisfy given performance requirements. The microstructural gradation gives rise to continuously or discretely changing material properties which complicate FGM analysis. Various techniques have been developed during the past several decades for analyzing traditional composites and many of these have been adapted for the analysis of FGMs. Most of the available techniques use the so-called uncoupled approach in order to analyze graded structures. These techniques ignore the effect of microstructural gradation by employing specific spatial material property variations that are either assumed or obtained by local homogenization. The higher-order theory for functionally graded materials (HOTFGM) is a coupled approach developed by Aboudi et al. (1999) which takes the effect of microstructural gradation into consideration and does not ignore the local-global interaction of the spatially variable inclusion phase(s). Despite its demonstrated utility, however, the original formulation of the higher-order theory is computationally intensive. Herein, an efficient reformulation of the original higher-order theory for two-dimensional elastic problems is developed and validated. The use of the local-global conductivity and local-global stiffness matrix approach is made in order to reduce the number of equations involved. In this approach, surface-averaged quantities are the primary variables which replace volume-averaged quantities employed in the original formulation. The reformulation decreases the size of the global conductivity and stiffness matrices by approximately sixty percent. Various thermal, mechanical, and combined thermomechanical problems are analyzed in order to validate the accuracy of the reformulated theory through comparison with analytical and finite-element solutions. The presented results illustrate the efficiency of the reformulation and its
Molecular Behavior of DNA Origami in Higher-Order Self-Assembly
Li, Zhe; Liu, Minghui; Wang, Lei; Nangreave, Jeanette; Yan, Hao; Liu, Yan
2011-01-01
DNA-based self-assembly is a unique method for achieving higher-order molecular architectures made possible by the fact that DNA is a programmable information-coding polymer. In the past decade, two main types of DNA nanostructures have been developed: branch-shaped DNA tiles with small dimensions (commonly up to ~20 nm) and DNA origami tiles with larger dimensions (up to ~100 nm). Here we aimed to determine the important factors involved in the assembly of DNA origami superstructures. We constructed a new series of rectangular-shaped DNA origami tiles in which parallel DNA helices are arranged in a zigzag pattern when viewed along the DNA helical axis, a design conceived in order to relax an intrinsic global twist found in the original planar, rectangular origami tiles. Self-associating zigzag tiles were found to form linear arrays in both diagonal directions, while planar tiles showed significant growth in only one direction. Although the series of zigzag tiles were designed to promote two-dimensional array formation, one-dimensional linear arrays and tubular structures were observed instead. We discovered that the dimensional aspect ratio of the origami unit tiles and intertile connection design play important roles in determining the final products, as revealed by atomic force microscopy imaging. This study provides insight into the formation of higher-order structures from self-assembling DNA origami tiles, revealing their unique behavior in comparison with conventional DNA tiles having smaller dimensions. PMID:20825190
Molecular Behavior of DNA Origami in Higher-Order Self-Assembly
Li, Zhe; Liu, Minghui; Lei, Wang; Nangreave, Jeanette; Yan, Hao; Liu, Yan
2010-09-08
DNA-based self-assembly is a unique method for achieving higher-order molecular architectures made possible by the fact that DNA is a programmable information-coding polymer. In the past decade, two main types of DNA nanostructures have been developed: branch-shaped DNA tiles with small dimensions (commonly up to ~20 nm) and DNA origami tiles with larger dimensions (up to ~100 nm). Here we aimed to determine the important factors involved in the assembly of DNA origami superstructures. We constructed a new series of rectangular-shaped DNA origami tiles in which parallel DNA helices are arranged in a zigzag pattern when viewed along the DNA helical axis, a design conceived in order to relax an intrinsic global twist found in the original planar, rectangular origami tiles. Self-associating zigzag tiles were found to form linear arrays in both diagonal directions, while planar tiles showed significant growth in only one direction. Although the series of zigzag tiles were designed to promote two-dimensional array formation, one-dimensional linear arrays and tubular structures were observed instead. We discovered that the dimensional aspect ratio of the origami unit tiles and intertile connection design play important roles in determining the final products, as revealed by atomic force microscopy imaging. This study provides insight into the formation of higher-order structures from self-assembling DNA origami tiles, revealing their unique behavior in comparison with conventional DNA tiles having smaller dimensions.
Impedance Eduction in Ducts with Higher-Order Modes and Flow
NASA Technical Reports Server (NTRS)
Watson, Willie R.; Jones, Michael G.
2009-01-01
An impedance eduction technique, previously validated for ducts with plane waves at the source and duct termination planes, has been extended to support higher-order modes at these locations. Inputs for this method are the acoustic pressures along the source and duct termination planes, and along a microphone array located in a wall either adjacent or opposite to the test liner. A second impedance eduction technique is then presented that eliminates the need for the microphone array. The integrity of both methods is tested using three sound sources, six Mach numbers, and six selected frequencies. Results are presented for both a hardwall and a test liner (with known impedance) consisting of a perforated plate bonded to a honeycomb core. The primary conclusion of the study is that the second method performs well in the presence of higher-order modes and flow. However, the first method performs poorly when most of the microphones are located near acoustic pressure nulls. The negative effects of the acoustic pressure nulls can be mitigated by a judicious choice of the mode structure in the sound source. The paper closes by using the first impedance eduction method to design a rectangular array of 32 microphones for accurate impedance eduction in the NASA LaRC Curved Duct Test Rig in the presence of expected measurement uncertainties, higher order modes, and mean flow.
Transverse vibrations of shear-deformable beams using a general higher order theory
NASA Technical Reports Server (NTRS)
Kosmatka, J. B.
1993-01-01
A general higher order theory is developed to study the static and vibrational behavior of beam structures having an arbitrary cross section that utilizes both out-of-plane shear-dependent warping and in-plane (anticlastic) deformations. The equations of motion are derived via Hamilton's principle, where the full 3D constitutive relations are used. A simplified version of the general higher-order theory is also presented for beams having an arbitrary cross section that includes out-of-plane shear deformation but assumes that stresses within the cross section and in-plane deformations are negligible. This simplified model, which is accurate for long to moderately short wavelengths, offers substantial improvements over existing higher order theories that are limited to beams with thin rectangular cross sections. The current approach will be very useful in the study of thin-wall closed-cell beams such as airfoil-type sections where the magnitude of shear-related cross-sectional warping is significant.
On the polarization of non-Gaussian optical quantum field: Higher-order optical-polarization
Singh, Ravi S.; Prakash, Hari
2013-06-15
Polarization of light signifies transversal, anisotropic and asymmetrical statistical properties of electromagnetic radiation about the direction of propagation. Traditionally, optical-polarization is characterized by Stokes’ theory susceptible to be insufficient in assessing the polarization structure of optical quantum fields and, also, does not decipher the twin characteristic polarization parameters (‘ratio of real amplitudes and difference in phases’). An alternative way, in the spirit of classical description of optical-polarization, is introduced which can be generalized to deal higher-order polarization of quantum light, particularly, prepared in non-Gaussian Schrodinger Cat or Cat-like states and entangled bi-modal coherent states. On account of pseudo mono-modal or multi-modal nature of such optical quantum field, higher-order polarization is seen to be highly sensitive to the basis of description. -- Highlights: •We have generalized the usual concept of optical-polarization. •A concept of higher-order optical-polarization is introduced. •This concept is applied to compute the polarization-parameters of non-Gaussian Optical field. •To the best of our knowledge, no study is performed which investigates such optical quantum field.
Some classes of gravitational shock waves from higher order theories of gravity
NASA Astrophysics Data System (ADS)
Oikonomou, V. K.
2017-02-01
We study the gravitational shock wave generated by a massless high energy particle in the context of higher order gravities of the form F(R,R_{μν}R^{μν},R_{μναβ}R^{μν αβ}). In the case of F(R) gravity, we investigate the gravitational shock wave solutions corresponding to various cosmologically viable gravities, and as we demonstrate the solutions are rescaled versions of the Einstein-Hilbert gravity solution. Interestingly enough, other higher order gravities result to the general relativistic solution, except for some specific gravities of the form F(R_{μν}R^{μν}) and F(R,R_{μν}R^{μν}), which we study in detail. In addition, when realistic Gauss-Bonnet gravities of the form R+F(G) are considered, the gravitational shock wave solutions are identical to the general relativistic solution. Finally, the singularity structure of the gravitational shock waves solutions is studied, and it is shown that the effect of higher order gravities makes the singularities milder in comparison to the general relativistic solutions, and in some particular cases the singularities seem to be absent.
Observation and Electromechanical Actuation of Higher-Order Buckling Eigenmodes of NEMS
NASA Astrophysics Data System (ADS)
Carr, Stephen; Wybourne, Martin
2003-03-01
We report on observation and capacitive excitation of higher-order buckling eigenmodes of SiO2 nanomechanical beams. The suspended structures, fabricated by e-beam lithography and plasma etching, consist of 500 nm of thermal oxide and a metal overlayer ( ˜ 100 nm) with a range of lengths and widths. In previous work we studied the buckling transition [1], finding the fundamental (n = 1) as the only stable buckling eigenmode. Recently we have observed higher-order (n = 2, 3) buckling eigenmodes which are stable after release from plasma etching. Electromechanical transitions from n = 3 to n = 2 and n = 3 to n = 1 have been induced by applied DC and AC bias through capacitively coupled electrodes. Possible explanations for the observed stability of the higher-order modes, as well as results from current experiments designed to probe the electromechanical resonance spectrum, will be discussed. [1] S.M. Carr and M.N. Wybourne, Applied Physics Letters, in press (2003).
Ability, breadth, and parsimony in computational models of higher-order cognition.
Cassimatis, Nicholas L; Bello, Paul; Langley, Pat
2008-12-01
Computational models will play an important role in our understanding of human higher-order cognition. How can a model's contribution to this goal be evaluated? This article argues that three important aspects of a model of higher-order cognition to evaluate are (a) its ability to reason, solve problems, converse, and learn as well as people do; (b) the breadth of situations in which it can do so; and (c) the parsimony of the mechanisms it posits. This article argues that fits of models to quantitative experimental data, although valuable for other reasons, do not address these criteria. Further, using analogies with other sciences, the history of cognitive science, and examples from modern-day research programs, this article identifies five activities that have been demonstrated to play an important role in our understanding of human higher-order cognition. These include modeling within a cognitive architecture, conducting artificial intelligence research, measuring and expanding a model's ability, finding mappings between the structure of different domains, and attempting to explain multiple phenomena within a single model.
NASA Astrophysics Data System (ADS)
Ma, Zhipeng; Park, Seongsu; Yamashita, Naoki; Kawai, Kentaro; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu
2016-06-01
DNA origami provides a versatile method for the construction of nanostructures with defined shape, size and other properties; such nanostructures may enable a hierarchical assembly of large scale architecture for the placement of other nanomaterials with atomic precision. However, the effective use of these higher order structures as functional components depends on knowledge of their assembly behavior and mechanical properties. This paper demonstrates construction of higher order DNA origami arrays with controlled orientations based on the formation of two types of DNA junctions: anti-parallel and parallel double crossovers. A two-step assembly process, in which preformed rectangular DNA origami monomer structures themselves undergo further self-assembly to form numerically unlimited arrays, was investigated to reveal the influences of assembly parameters. AFM observations showed that when parallel double crossover DNA junctions are used, the assembly of DNA origami arrays occurs with fewer monomers than for structures formed using anti-parallel double crossovers, given the same assembly parameters, indicating that the configuration of parallel double crossovers is not energetically preferred. However, the direct measurement by AFM force-controlled mapping shows that both DNA junctions of anti-parallel and parallel double crossovers have homogeneous mechanical stability with any part of DNA origami.
Higher-order Mode Calculations, predictions and Overview of Damping Schemes for ERLs
Robert Rimmer
2005-03-19
This paper gives a brief review of computational methods for calculating higher-order mode (HOM) impedances for RF structures, the cases for which they are appropriate and some comparisons with measurements. An overview of damping schemes suitable for moderate to high current energy recovered linacs (ERL's), is presented, with a discussion of the pro's and con's of each. The influence of number of cells per cavity, cell shape and cell-to-cell coupling are described. The Jefferson Lab Ampere-class cryomodule concept is presented as an example and the issue of HOM power is highlighted.
Higher order multi-dimensional extensions of Cesàro theorem
NASA Astrophysics Data System (ADS)
Accardi, Luigi; Ji, Un Cig; Saitô, Kimiaki
2015-12-01
The Cesàro theorem is extended to the cases: (1) higher order Cesàro mean for sequence (discrete case); and (2) higher order, multi-dimensional and continuous Cesàro mean for functions. Also, we study the Cesàro theorem for the case of positive-order.
Higher Order Thinking Skills among Secondary School Students in Science Learning
ERIC Educational Resources Information Center
Saido, Gulistan Mohammed; Siraj, Saedah; Bin Nordin, Abu Bakar; Al Amedy, Omed Saadallah
2015-01-01
A central goal of science education is to help students to develop their higher order thinking skills to enable them to face the challenges of daily life. Enhancing students' higher order thinking skills is the main goal of the Kurdish Science Curriculum in the Iraqi-Kurdistan region. This study aimed at assessing 7th grade students' higher order…
Testing higher-order Lagrangian perturbation theory against numerical simulation. 1: Pancake models
NASA Technical Reports Server (NTRS)
Buchert, T.; Melott, A. L.; Weiss, A. G.
1993-01-01
We present results showing an improvement of the accuracy of perturbation theory as applied to cosmological structure formation for a useful range of quasi-linear scales. The Lagrangian theory of gravitational instability of an Einstein-de Sitter dust cosmogony investigated and solved up to the third order is compared with numerical simulations. In this paper we study the dynamics of pancake models as a first step. In previous work the accuracy of several analytical approximations for the modeling of large-scale structure in the mildly non-linear regime was analyzed in the same way, allowing for direct comparison of the accuracy of various approximations. In particular, the Zel'dovich approximation (hereafter ZA) as a subclass of the first-order Lagrangian perturbation solutions was found to provide an excellent approximation to the density field in the mildly non-linear regime (i.e. up to a linear r.m.s. density contrast of sigma is approximately 2). The performance of ZA in hierarchical clustering models can be greatly improved by truncating the initial power spectrum (smoothing the initial data). We here explore whether this approximation can be further improved with higher-order corrections in the displacement mapping from homogeneity. We study a single pancake model (truncated power-spectrum with power-spectrum with power-index n = -1) using cross-correlation statistics employed in previous work. We found that for all statistical methods used the higher-order corrections improve the results obtained for the first-order solution up to the stage when sigma (linear theory) is approximately 1. While this improvement can be seen for all spatial scales, later stages retain this feature only above a certain scale which is increasing with time. However, third-order is not much improvement over second-order at any stage. The total breakdown of the perturbation approach is observed at the stage, where sigma (linear theory) is approximately 2, which corresponds to the
Li, Xing; Yeung, Darwin F; Fiegen, Ann M; Sodroski, Joseph
2011-08-12
Many tripartite motif (TRIM) proteins self-associate, forming dimers and higher order complexes. For example, dimers of TRIM5α, a host factor that restricts retrovirus infection, assemble into higher order arrays on the surface of the viral capsid, resulting in an increase in avidity. Here we show that the higher order association of different TRIM proteins exhibits a wide range of efficiencies. Homologous association (self-association) was more efficient than the heterologous association of different TRIM proteins, indicating that specificity determinants of higher order self-association exist. To investigate the structural determinants of higher order self-association, we studied TRIM mutants and chimeras. These studies revealed the following: 1) the RING domain contributes to the efficiency of higher order self-association, which enhances the binding of TRIM5α to the human immunodeficiency virus (HIV-1) capsid; 2) the RING and B-box 2 domains work together as a homologous unit to promote higher order association of dimers; 3) dimerization is probably required for efficient higher order self-association; 4) the Linker 2 region contributes to higher order self-association, independently of effects of Linker 2 changes on TRIM dimerization; and 5) for efficiently self-associating TRIM proteins, the B30.2(SPRY) domain is not required for higher order self-association. These results support a model in which both ends of the core TRIM dimer (RING-B-box 2 at one end and Linker 2 at the other) contribute to the formation of higher order arrays.
Fundamental measure theory for smectic phases: Scaling behavior and higher order terms
NASA Astrophysics Data System (ADS)
Wittmann, René; Marechal, Matthieu; Mecke, Klaus
2014-08-01
The recent extension of Rosenfeld's fundamental measure theory to anisotropic hard particles predicts nematic order of rod-like particles. Our analytic study of different aligned shapes provides new insights into the structure of this density functional, which is basically founded on experience with hard spheres. We combine scaling arguments with dimensional crossover and motivate a modified expression, which enables an appropriate description of smectic layering. We calculate the nematic-smectic-A transition of monodisperse hard spherocylinders with and without orientational degrees of freedom and present the equation of state and phase diagram including these two liquid crystalline phases in good agreement with simulations. We also find improved results related to the isotropic-nematic interface. We discuss the quality of empirical corrections and the convergence towards an exact second virial coefficient, including higher order terms.
Fundamental measure theory for smectic phases: scaling behavior and higher order terms.
Wittmann, René; Marechal, Matthieu; Mecke, Klaus
2014-08-14
The recent extension of Rosenfeld's fundamental measure theory to anisotropic hard particles predicts nematic order of rod-like particles. Our analytic study of different aligned shapes provides new insights into the structure of this density functional, which is basically founded on experience with hard spheres. We combine scaling arguments with dimensional crossover and motivate a modified expression, which enables an appropriate description of smectic layering. We calculate the nematic-smectic-A transition of monodisperse hard spherocylinders with and without orientational degrees of freedom and present the equation of state and phase diagram including these two liquid crystalline phases in good agreement with simulations. We also find improved results related to the isotropic-nematic interface. We discuss the quality of empirical corrections and the convergence towards an exact second virial coefficient, including higher order terms.
Double Quarter Wave Crab Cavity Field Profile Analysis and Higher Order Mode Characterization
Marques, Carlos; Xiao, B. P.; Belomestnykh, S.
2014-06-01
The Large Hadron Collider (LHC) is underway for a major upgrade to increase its luminosity by an order of magnitude beyond its original design specifications. This novel machine configuration known as the High Luminosity LHC (HL-LHC) will rely on various innovative technologies including very compact and ultra-precise superconducting crab cavities for beam rotation. A double quarter wave crab cavity (DQWCC) has been designed at Brookhaven National Laboratory for the HL-LHC. This cavity as well as the structural support components were fabricated and assembled at Niowave. The field profile of the crabbing mode for the DQWCC was investigated using a phase shift bead pulling technique and compared with simulated results to ensure proper operation or discover discrepancies from modeled results and/or variation in fabrication tolerances. Higher-Order Mode (HOM) characterization was also performed and correlated with simulations.
A fully coupled model for actuation of higher order modes of Lamb waves
NASA Astrophysics Data System (ADS)
Ren, Baiyang; Lissenden, Cliff J.
2017-02-01
Lamb waves have proven to be a valuable tool for structural health monitoring (SHM) of plate-like structures susceptible to degradation and failure. It is well-known that their multi-modal propagation characteristic could be both a challenge and an opportunity. Piezoelectric transducers are widely used in SHM applications because of their low cost, small profile and high electromechanical coupling. Properly designing a piezoelectric transducer to excite a particular mode is of great importance to successful SHM practice. Mode tuning capability of piezoelectric transducers has been studied both theoretically and experimentally in the literature for exciting A0 and S0 modes. However, the higher order Lamb waves are not fully studied for their tuning capability. Also, the transducer is usually modeled separately from the waveguide and their coupling is through the in-plane surface traction. This assumption may induce inaccuracy if the dynamics of the actuator are not negligible. Additionally, the driving circuit is not usually included in the current actuator-waveguide models such that the power of excited wave could not be evaluated. In this work, a fully coupled finite element model created for general Lamb wave excitation using piezoelectric transducers is developed. The model comprises three components, electrical driving circuit, piezoelectric element and linear elastic waveguide. The preferential excitation of higher order Lamb wave modes using a single piezoelectric element has been studied and demonstrated experimentally on aluminum plates.
Gjelstrup, Louise Carstensen; Andersen, Stig Henrik; Petersen, Steen Vang; Enghild, Jan J; Blom, Anna M; Vorup-Jensen, Thomas; Thiel, Steffen
2011-10-01
Heteroclitic monoclonal antibodies are characterized by the ability to bind multiple epitopes with little or no similarity. Such antibodies have been reported earlier, but insight into to the molecular basis of this propensity is limited. Here we report that the KIM185 antibody to human CD18 reacts with the plasma protein C4b-binding protein (C4BP). This was revealed during affinity purification procedures where human serum was incubated with surfaces coated with monoclonal antibodies to CD18. Other monoclonal antibodies to CD18 (KIM127 and TS1/18) showed no such interaction with C4BP. We constructed a sandwich-type time-resolved immunofluorometric assay using KIM185 both as capture and developing antibody. By use of proteolytic fragments of KIM185 and recombinant deletion mutants of C4BP the interaction sites were mapped to the variable region of KIM185 and the oligomerization domain of C4BP, respectively. C4BP is a large oligomeric plasma protein that binds activated complement factor C4b and other endogenous ligands as well as microorganisms. By use of the recent crystallographic data on the structure of CD11c/CD18 and prediction of the secondary structure of the C4BP oligomerization domain, we show that epitopes bound by KIM185 in these proteins are unlikely to share any major structural similarity. However, both antigens may form oligomers that would enable avid binding by the antibody. Our report points to the astonishing ability of heteroclitic antibodies to accommodate the binding of multiple proteins with no or little structural similarity within the confined space of the variable regions.
Scott, Kristin M; Barbarin, Oscar A; Brown, Jeffrey M
2013-01-01
This study examines the relations of higher order (i.e., abstract) thinking (HOT) skills to specific domains of social competence in Black boys (n = 108) attending publicly sponsored prekindergarten (pre-K) programs. Data for the study were collected as part of the National Center for Early Development and Learning (NCEDL) Multi-State Study, a national, longitudinal study examining the quality and outcomes in a representative sample of publicly sponsored pre-K programs in six states (N = 240). Pre-K and kindergarten teachers rated randomly selected children on measures of abstract thinking, self-regulation, and social functioning at the beginning and end of each school year. Applying structural equation modeling, compared with earlier time points, HOT measured in the fall of kindergarten significantly predicted each of the domains of social competence in the spring of kindergarten, with the exception of peer social skills, while controlling for general cognitive ability. Results suggest that early intervention to improve HOT may be an effective and more focused approach to address concerns about Black boys' early social competencies in specific domains and potentially reduce the risk of later social difficulties.
Substance and artifact in the higher-order factors of the Big Five.
McCrae, Robert R; Yamagata, Shinji; Jang, Kerry L; Riemann, Rainer; Ando, Juko; Ono, Yutaka; Angleitner, Alois; Spinath, Frank M
2008-08-01
J. M. Digman (1997) proposed that the Big Five personality traits showed a higher-order structure with 2 factors he labeled alpha and beta. These factors have been alternatively interpreted as heritable components of personality or as artifacts of evaluative bias. Using structural equation modeling, the authors reanalyzed data from a cross-national twin study and from American cross-observer studies and analyzed new multimethod data from a German twin study. In all analyses, artifact models outperformed substance models by root-mean-square error of approximation criteria, but models combining both artifact and substance were slightly better. These findings suggest that the search for the biological basis of personality traits may be more profitably focused on the 5 factors themselves and their specific facets, especially in monomethod studies.
Two-photon or higher-order absorbing optical materials and methods of use
NASA Technical Reports Server (NTRS)
Marder, Seth (Inventor); Perry, Joseph (Inventor)
2012-01-01
Compositions capable of simultaneous two-photon absorption and higher order absorptivities are provided. Compounds having a donor-pi-donor or acceptor-pi-acceptor structure are of particular interest, where the donor is an electron donating group, acceptor is an electron accepting group, and pi is a pi bridge linking the donor and/or acceptor groups. The pi bridge may additionally be substituted with electron donating or withdrawing groups to alter the absorptive wavelength of the structure. Also disclosed are methods of generating an excited state of such compounds through optical stimulation with light using simultaneous absorption of photons of energies individually insufficient to achieve an excited state of the compound, but capable of doing so upon simultaneous absorption of two or more such photons. Applications employing such methods are also provided, including controlled polymerization achieved through focusing of the light source(s) used.
Hatch, David R.; Del-Castillo-Negrete, Diego B; Terry, P.W.
2012-01-01
Higher order singular value decomposition (HOSVD) is explored as a tool for analyzing and compressing gyrokinetic data. An efficient numerical implementation of an HOSVD algorithm is described. HOSVD is used to analyze the full six-dimensional (three spatial, two velocity space, and time dimensions) gyrocenter distribution function from gyrokinetic simulations of ion temperature gradient, electron temperature gradient, and trapped electron mode driven turbulence. The HOSVD eigenvalues for the velocity space coordinates decay very rapidly, indicating that only a few structures in velocity space can capture the most important dynamics. In almost all of the cases studied, HOSVD extracts parallel velocity space structures which are very similar to orthogonal polynomials. HOSVD is also used to compress gyrokinetic datasets, an application in which it is shown to significantly outperform the more commonly used singular value decomposition. It is shown that the effectiveness of the HOSVD compression improves as the dimensionality of the dataset increases. (C) 2012 Elsevier Inc. All rights reserved.
Higher-order nonlinear electromechanical effects in wurtzite GaN/AlN quantum dots.
Bahrami-Samani, Mehrdad; Patil, Sunil R; Melnik, Roderick
2010-12-15
As we demonstrated earlier, conventional mathematical models based on linear approximations may be inadequate in the analysis of properties of low-dimensional nanostructures and band structure calculations. In this work, a general three-dimensional axisymmetric coupled electromechanical model accounting for lattice mismatch, spontaneous polarization and higher-order nonlinear electrostriction effects has been applied to analyze properties of GaN/AlN quantum dots coupled with wetting layer. The generalized model that accounts for five independent electrostriction coefficients has been solved numerically via a finite-element implementation. The results, exemplified for truncated conical GaN/AlN quantum dots, demonstrate that the effect of nonlinear electrostriction in GaN/AlN nanoheterostructure quantum dots could be significant. In particular, the influence of nonlinear electromechanical effects on optoelectronic properties is highlighted by the results on band structure calculations based on a multiband effective mass theory.
Higher-order exchange interactions leading to metamagnetism in FeRh
NASA Astrophysics Data System (ADS)
Barker, Joseph; Chantrell, Roy W.
2015-09-01
The origin of the metamagnetic antiferromagnetic-ferromagnetic phase transition of FeRh is a subject of debate. Competing explanations invoke magnetovolume effects or a purely thermodynamic transition within the spin system. It is experimentally difficult to observe the changes in the magnetic system and the lattice simultaneously, leading to conflicting evidence over which mechanism causes the phase transition. A noncollinear electronic structure study by Mryasov [Phase Transitions 78, 197 (2005), 10.1080/01411590412331316591] showed that nonlinear behavior of the Rh moment leads to higher-order exchange terms in FeRh. Using atomistic spin dynamics, we show that the phase transition can occur due to the competition between bilinear and the higher-order four spin exchange terms in an effective spin Hamiltonian. The phase transition we see is of first order and shows thermal hysteresis in agreement with experimental observations. Simulating subpicosecond laser heating, we show an agreement with pump-probe experiments with a ferromagnetic response on a picosecond time scale.
The impedance problem of wave diffraction by a strip with higher order boundary conditions
NASA Astrophysics Data System (ADS)
Castro, L. P.; Simões, A. M.
2013-10-01
This work is devoted to analyse an impedance boundary-transmission problem for the Helmholtz equation originated by a problem of wave diffraction by an infinite strip with higher order imperfect boundary conditions. A constructive approach of operator relations is built, which allows a transparent interpretation of the problem in an operator theory framework. In particular, different types of operator relations are exhibited for different types of operators acting between Lebesgue and Sobolev spaces on a finite interval and the positive half-line. All this has consequences in the understanding of the structure of this type of problems. In particular, a Fredholm characterization of the problem is obtained in terms of the initial space order parameters. At the request of the author and the Proceedings Editor the above article has been replaced with a corrected version. The original PDF file supplied to AIP Publishing contained an error in the title of the article. The original title appeared as: "The Impedance Problem of Wave Diffraction by a trip with Higher Order Boundary Conditions." This article has been replaced and the title now appears correctly online. The corrected article was published on 8 November 2013.
The impedance problem of wave diffraction by a strip with higher order boundary conditions
Castro, L. P.; Simões, A. M.
2013-10-17
This work is devoted to analyse an impedance boundary-transmission problem for the Helmholtz equation originated by a problem of wave diffraction by an infinite strip with higher order imperfect boundary conditions. A constructive approach of operator relations is built, which allows a transparent interpretation of the problem in an operator theory framework. In particular, different types of operator relations are exhibited for different types of operators acting between Lebesgue and Sobolev spaces on a finite interval and the positive half-line. All this has consequences in the understanding of the structure of this type of problems. In particular, a Fredholm characterization of the problem is obtained in terms of the initial space order parameters. At the request of the author and the Proceedings Editor the above article has been replaced with a corrected version. The original PDF file supplied to AIP Publishing contained an error in the title of the article. The original title appeared as: 'The Impedance Problem of Wave Diffraction by a trip with Higher Order Boundary Conditions.' This article has been replaced and the title now appears correctly online. The corrected article was published on 8 November 2013.
Achieving Higher Energies via Passively Driven X-band Structures
NASA Astrophysics Data System (ADS)
Sipahi, Taylan; Sipahi, Nihan; Milton, Stephen; Biedron, Sandra
2014-03-01
Due to their higher intrinsic shunt impedance X-band accelerating structures significant gradients with relatively modest input powers, and this can lead to more compact particle accelerators. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3 GHz L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the design details of the X-band structures that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structure while driven solely by the beam from the L-band system.
Lagrangian-Hamiltonian unified formalism for autonomous higher order dynamical systems
NASA Astrophysics Data System (ADS)
Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso
2011-09-01
The Lagrangian-Hamiltonian unified formalism of Skinner and Rusk was originally stated for autonomous dynamical systems in classical mechanics. It has been generalized for non-autonomous first-order mechanical systems, as well as for first-order and higher order field theories. However, a complete generalization to higher order mechanical systems is yet to be described. In this work, after reviewing the natural geometrical setting and the Lagrangian and Hamiltonian formalisms for higher order autonomous mechanical systems, we develop a complete generalization of the Lagrangian-Hamiltonian unified formalism for these kinds of systems, and we use it to analyze some physical models from this new point of view.
Effect of higher-order multipole moments on the Stark line shape
NASA Astrophysics Data System (ADS)
Gomez, T. A.; Nagayama, T.; Kilcrease, D. P.; Montgomery, M. H.; Winget, D. E.
2016-08-01
Spectral line shapes are sensitive to plasma conditions and are often used to diagnose electron density of laboratory plasmas as well as astrophysical plasmas. Stark line-shape models take into account the perturbation of the radiator's energy structure due to the Coulomb interaction with the surrounding charged particles. Solving this Coulomb interaction is challenging and is commonly approximated via a multipole expansion. However, most models include only up to the second term of the expansion (the dipole term). While there have been studies on the higher-order terms due to one of the species (i.e., either ions or electrons), there is no model that includes the terms beyond dipole from both species. Here, we investigate the importance of the higher-order multipole terms from both species on the Hβ line shape. First, we find that it is important to include higher-order terms consistently from both ions and electrons to reproduce measured line-shape asymmetry. Next, we find that the line shape calculated with the dipole-only approximation becomes inaccurate as density increases. It is necessary to include up to the third (quadrupole) term to compute the line shape accurately within 2%. Since most existing models include only up to the dipole terms, the densities inferred with such models are in question. We find that the model without the quadrupole term slightly underestimates the density, and the discrepancy becomes as large as 12% at high densities. While the case of study is limited to Hβ, we expect similar impact on other lines.
Questions for Assessing Higher-Order Cognitive Skills: It's Not Just Bloom's
ERIC Educational Resources Information Center
Lemons, Paula P.; Lemons, J. Derrick
2013-01-01
We present an exploratory study of biologists' ideas about higher-order cognition questions. We documented the conversations of biologists who were writing and reviewing a set of higher-order cognition questions. Using a qualitative approach, we identified the themes of these conversations. Biologists in our study used Bloom's Taxonomy to…
Family Consumer Sciences Teachers' Use of Technology to Teach Higher Order Thinking Skills
ERIC Educational Resources Information Center
Hirose, Beth Erica
2009-01-01
Family and consumer sciences (FACS) high school teachers were surveyed on their use of technology to teach higher order thinking skills (HOTS). This study determined if teachers had enough support and training to use technology. Lesson plans were accumulated that required both technology and higher order thinking skills. These lessons were then…
Improving Computer-Assisted Instruction in Teaching Higher-Order Skills
ERIC Educational Resources Information Center
Sinclair, Kelsey J.; Renshaw, Carl E.; Taylor, Holly A.
2004-01-01
Computer-assisted instruction (CAI) has been shown to enhance rote memory skills and improve higher order critical thinking skills. The challenge now is to identify what aspects of CAI improve which specific higher-order skills. This study focuses on the effectiveness of using CAI to teach logarithmic graphing and dimensional analysis. Two groups…
Ability, Breadth, and Parsimony in Computational Models of Higher-Order Cognition
ERIC Educational Resources Information Center
Cassimatis, Nicholas L.; Bello, Paul; Langley, Pat
2008-01-01
Computational models will play an important role in our understanding of human higher-order cognition. How can a model's contribution to this goal be evaluated? This article argues that three important aspects of a model of higher-order cognition to evaluate are (a) its ability to reason, solve problems, converse, and learn as well as people do;…
Teaching Higher Order Thinking in the Introductory MIS Course: A Model-Directed Approach
ERIC Educational Resources Information Center
Wang, Shouhong; Wang, Hai
2011-01-01
One vision of education evolution is to change the modes of thinking of students. Critical thinking, design thinking, and system thinking are higher order thinking paradigms that are specifically pertinent to business education. A model-directed approach to teaching and learning higher order thinking is proposed. An example of application of the…
From "Hello" to Higher-Order Thinking: The Effect of Coaching and Feedback on Online Chats
ERIC Educational Resources Information Center
Stein, David S.; Wanstreet, Constance E.; Slagle, Paula; Trinko, Lynn A.; Lutz, Michelle
2013-01-01
This exploratory study examined the effect of a coaching and feedback intervention in teaching presence and social presence on higher-order thinking in an online community of inquiry. Coaching occurred before each chat, and feedback was provided immediately afterwards. The findings suggest that over time, the frequency of higher-order thinking…
Assessing Higher-Order Cognitive Constructs by Using an Information-Processing Framework
ERIC Educational Resources Information Center
Dickison, Philip; Luo, Xiao; Kim, Doyoung; Woo, Ada; Muntean, William; Bergstrom, Betty
2016-01-01
Designing a theory-based assessment with sound psychometric qualities to measure a higher-order cognitive construct is a highly desired yet challenging task for many practitioners. This paper proposes a framework for designing a theory-based assessment to measure a higher-order cognitive construct. This framework results in a modularized yet…
Authentic Instruction for 21st Century Learning: Higher Order Thinking in an Inclusive School
ERIC Educational Resources Information Center
Preus, Betty
2012-01-01
The author studied a public junior high school identified as successfully implementing authentic instruction. Such instruction emphasizes higher order thinking, deep knowledge, substantive conversation, and value beyond school. To determine in what ways higher order thinking was fostered both for students with and without disabilities, the author…
An Analysis of Higher-Order Thinking on Algebra I End-of-Course Tests
ERIC Educational Resources Information Center
Thompson, Tony
2011-01-01
This research provides insight into one US state's effort to incorporate higher-order thinking on its Algebra I End-of-Course tests. To facilitate the inclusion of higher-order thinking, the state used "Dimensions of Thinking" (Marzano et al., 1988) and "Bloom's Taxonomy" (Bloom et al., 1956). An analysis of Algebra I test…
ERIC Educational Resources Information Center
Schraw, Gregory, Ed.; Robinson, Daniel H., Ed.
2011-01-01
This volume examines the assessment of higher order thinking skills from the perspectives of applied cognitive psychology and measurement theory. The volume considers a variety of higher order thinking skills, including problem solving, critical thinking, argumentation, decision making, creativity, metacognition, and self-regulation. Fourteen…
ERIC Educational Resources Information Center
Fischer, Christopher; Bol, Linda; Pribesh, Shana
2011-01-01
This study investigated the extent to which higher-order thinking skills are promoted in social studies classes in high schools that are implementing smaller learning communities (SLCs). Data collection in this mixed-methods study included classroom observations and in-depth interviews. Findings indicated that higher-order thinking was rarely…
Assessing Teachers' Beliefs Regarding Issues Pertaining to Instruction of Higher Order Thinking.
ERIC Educational Resources Information Center
Shwartzer, Noa; Zohar, Anat
The purposes of this study are to describe the development and validation of a research instrument for assessing teachers' beliefs regarding issues pertaining to the instruction of higher order thinking, and to explore the beliefs of Israeli science teachers regarding issues pertaining to instruction of higher order thinking. This paper describes…
NASA Astrophysics Data System (ADS)
Chobanyan, E.; Ilić, M. M.; Notaroš, B. M.
2015-05-01
A novel double-higher-order entire-domain volume integral equation (VIE) technique for efficient analysis of electromagnetic structures with continuously inhomogeneous dielectric materials is presented. The technique takes advantage of large curved hexahedral discretization elements—enabled by double-higher-order modeling (higher-order modeling of both the geometry and the current)—in applications involving highly inhomogeneous dielectric bodies. Lagrange-type modeling of an arbitrary continuous variation of the equivalent complex permittivity of the dielectric throughout each VIE geometrical element is implemented, in place of piecewise homogeneous approximate models of the inhomogeneous structures. The technique combines the features of the previous double-higher-order piecewise homogeneous VIE method and continuously inhomogeneous finite element method (FEM). This appears to be the first implementation and demonstration of a VIE method with double-higher-order discretization elements and conformal modeling of inhomogeneous dielectric materials embedded within elements that are also higher (arbitrary) order (with arbitrary material-representation orders within each curved and large VIE element). The new technique is validated and evaluated by comparisons with a continuously inhomogeneous double-higher-order FEM technique, a piecewise homogeneous version of the double-higher-order VIE technique, and a commercial piecewise homogeneous FEM code. The examples include two real-world applications involving continuously inhomogeneous permittivity profiles: scattering from an egg-shaped melting hailstone and near-field analysis of a Luneburg lens, illuminated by a corrugated horn antenna. The results show that the new technique is more efficient and ensures considerable reductions in the number of unknowns and computational time when compared to the three alternative approaches.
Zhai, Yi; Wang, Yan; Wang, Zhaoqi; Liu, Yongji; Zhang, Lin; He, Yuanqing; Chang, Shengjiang
2014-01-01
An achromatic element eliminating only longitudinal chromatic aberration (LCA) while maintaining transverse chromatic aberration (TCA) is established for the eye model, which involves the angle formed by the visual and optical axis. To investigate the impacts of higher-order aberrations on vision, the actual data of higher-order aberrations of human eyes with three typical levels are introduced into the eye model along visual axis. Moreover, three kinds of individual eye models are established to investigate the impacts of higher-order aberrations, chromatic aberration (LCA+TCA), LCA and TCA on vision under the photopic condition, respectively. Results show that for most human eyes, the impact of chromatic aberration on vision is much stronger than that of higher-order aberrations, and the impact of LCA in chromatic aberration dominates. The impact of TCA is approximately equal to that of normal level higher-order aberrations and it can be ignored when LCA exists.
How couples cope with the death of a twin or higher order multiple.
Swanson, Patricia B; Kane, Robert T; Pearsall-Jones, Jillian G; Swanson, Carl F; Croft, Maxine L
2009-08-01
Fifty-two Australian couples who had experienced the death of at least one member of a multiple birth (twin or higher order), with at least one survivor of that birth, were interviewed about their experiences at the time of the death, and since. This study compared parents' coping after the twins' deaths using the Beck Depression Inventory II, Perinatal Grief Scale, and unstructured interviews with some structured queries. Parents provided information on the influence of family, community and medical staff. According to retrospective reports, mothers experienced significantly more depression and grief than fathers at the time of loss. Both parents found the death of their twins grievous, but fathers, unlike mothers, were not encouraged to express their emotions. Although parents generally agreed about what helped them cope, fathers believed that they should be able to cope regardless of their grief. The strength of parents' spiritual beliefs had increased significantly since their loss, and there was some evidence that depressed and grieving mothers turned to spiritual support. Parents whose children died earlier reported levels of depression similar to those reported by parents whose children died later. To date, this is the largest study of grief in couples who have experienced the death of a twin and who have a surviving twin or higher order multiple.
Cross-ratio identities and higher-order poles of CHY-integrand
NASA Astrophysics Data System (ADS)
Cardona, Carlos; Feng, Bo; Gomez, Humberto; Huang, Rijun
2016-09-01
The evaluation of generic Cachazo-He-Yuan(CHY)-integrands is a big challenge and efficient computational methods are in demand for practical evaluation. In this paper, we propose a systematic decomposition algorithm by using cross-ratio identities, which provides an analytic and easy to implement method for the evaluation of any CHY-integrand. This algorithm aims to decompose a given CHY-integrand containing higher-order poles as a linear combination of CHY-integrands with only simple poles in a finite number of steps, which ultimately can be trivially evaluated by integration rules of simple poles. To make the method even more efficient for CHY-integrands with large number of particles and complicated higher-order pole structures, we combine the Λ-algorithm and the cross-ratio identities, and as a by-product it provides us a way to deal with CHY-integrands where the Λ-algorithm was not applicable in its original formulation.
Higher-order terms in sensitivity analysis through a differential approach
Dubi, A.; Dudziak, D.J.
1981-06-01
A differential approach to sensitivity analysis has been developed that eliminates some difficulties existing in previous work. The new development leads to simple explicit expressions for the first-order perturbation as well as any higher-order terms. The higher-order terms are dependent only on differentials of the transport operator, the unperturbed flux, the adjoint flux, and the unperturbed Green's function of the system.
a Higher Order Theory for STATIC-DYNAMIC Analysis of Laminated Plates Using a Warping Model
NASA Astrophysics Data System (ADS)
HASSIS, H.
2000-08-01
A higher order theory is developed to model the behaviour of laminated plates. This theory is based on a warping theory of plate deformation developed by Hassis [1]. Through comparison with elasticity solutions obtained with classical models [2-6] and the higher order theory of Lo et al.[7, 8], it is shown that the present theory correctly models effects not attainable by the low order theories.
Higher-order Schrödinger and Hartree–Fock equations
Carles, Rémi; Lucha, Wolfgang; Moulay, Emmanuel
2015-12-15
The domain of validity of the higher-order Schrödinger equations is analyzed for harmonic-oscillator and Coulomb potentials as typical examples. Then, the Cauchy theory for higher-order Hartree–Fock equations with bounded and Coulomb potentials is developed. Finally, the existence of associated ground states for the odd-order equations is proved. This renders these quantum equations relevant for physics.
Workshop on Higher-Order Spectral Analysis Held at Vail, Colorado on 28- 30 June 1989
1989-11-28
PROJECT REPORT Workshop on Higher-Order Spectral Analysis Jerry M. Mendel University of Southern California Dept. of Elec. Engineering-:ystems Los...material contained herein. I-o WORKSHOP ON HIGHER-ORDER SPECTRAL ANALYSIS June 28-30, 1989 Vail, Colorado SUMMARY by C. L. Nikias and J. M. Mendel A\\bout...ordering with cortical EEGs laboratory we reported in using bispectral recorded during sLow wave sleep having analysis of the hippocampal EEG during REM
ERIC Educational Resources Information Center
Scandura, Joseph M.; And Others
A quasi-systematic strategy of devising rule sets for problem solving is applied to ruler and compass geometrical constructions. "Lower order" rules consisting of basic skills and "higher order" rules which govern the selection and combination of lower order rules are identified by an analysis of problem types; three types of…
Geometric Integrators for Higher-Order Variational Systems and Their Application to Optimal Control
NASA Astrophysics Data System (ADS)
Colombo, Leonardo; Ferraro, Sebastián; Martín de Diego, David
2016-12-01
Numerical methods that preserve geometric invariants of the system, such as energy, momentum or the symplectic form, are called geometric integrators. In this paper we present a method to construct symplectic-momentum integrators for higher-order Lagrangian systems. Given a regular higher-order Lagrangian L:T^{(k)}Q→ R with k≥ 1, the resulting discrete equations define a generally implicit numerical integrator algorithm on T^{(k-1)}Q× T^{(k-1)}Q that approximates the flow of the higher-order Euler-Lagrange equations for L. The algorithm equations are called higher-order discrete Euler-Lagrange equations and constitute a variational integrator for higher-order mechanical systems. The general idea for those variational integrators is to directly discretize Hamilton's principle rather than the equations of motion in a way that preserves the invariants of the original system, notably the symplectic form and, via a discrete version of Noether's theorem, the momentum map. We construct an exact discrete Lagrangian L_d^e using the locally unique solution of the higher-order Euler-Lagrange equations for L with boundary conditions. By taking the discrete Lagrangian as an approximation of L_d^e, we obtain variational integrators for higher-order mechanical systems. We apply our techniques to optimal control problems since, given a cost function, the optimal control problem is understood as a second-order variational problem.
Liu, Chunlei; Murphy, Nicole E.; Li, Wei
2012-01-01
Diffusion MRI has become an invaluable tool for studying white matter microstructure and brain connectivity. The emergence of quantitative susceptibility mapping and susceptibility tensor imaging (STI) has provided another unique tool for assessing the structure of white matter. In the highly ordered white matter structure, diffusion MRI measures hindered water mobility induced by various tissue and cell membranes, while susceptibility sensitizes to the molecular composition and axonal arrangement. Integrating these two methods may produce new insights into the complex physiology of white matter. In this study, we investigated the relationship between diffusion and magnetic susceptibility in the white matter. Experiments were conducted on phantoms and human brains in vivo. Diffusion properties were quantified with the diffusion tensor model and also with the higher order tensor model based on the cumulant expansion. Frequency shift and susceptibility tensor were measured with quantitative susceptibility mapping and susceptibility tensor imaging. These diffusion and susceptibility quantities were compared and correlated in regions of single fiber bundles and regions of multiple fiber orientations. Relationships were established with similarities and differences identified. It is believed that diffusion MRI and susceptibility MRI provide complementary information of the microstructure of white matter. Together, they allow a more complete assessment of healthy and diseased brains. PMID:23507987
Mantel, Bruno; Stoffregen, Thomas A.; Campbell, Alain; Bardy, Benoît G.
2015-01-01
Body movement influences the structure of multiple forms of ambient energy, including optics and gravito-inertial force. Some researchers have argued that egocentric distance is derived from inferential integration of visual and non-visual stimulation. We suggest that accurate information about egocentric distance exists in perceptual stimulation as higher-order patterns that extend across optics and inertia. We formalize a pattern that specifies the egocentric distance of a stationary object across higher-order relations between optics and inertia. This higher-order parameter is created by self-generated movement of the perceiver in inertial space relative to the illuminated environment. For this reason, we placed minimal restrictions on the exploratory movements of our participants. We asked whether humans can detect and use the information available in this higher-order pattern. Participants judged whether a virtual object was within reach. We manipulated relations between body movement and the ambient structure of optics and inertia. Judgments were precise and accurate when the higher-order optical-inertial parameter was available. When only optic flow was available, judgments were poor. Our results reveal that participants perceived egocentric distance from the higher-order, optical-inertial consequences of their own exploratory activity. Analysis of participants’ movement trajectories revealed that self-selected movements were complex, and tended to optimize availability of the optical-inertial pattern that specifies egocentric distance. We argue that accurate information about egocentric distance exists in higher-order patterns of ambient energy, that self-generated movement can generate these higher-order patterns, and that these patterns can be detected and used to support perception of egocentric distance that is precise and accurate. PMID:25856410
Numerical calculation of beam shifts for higher-order Laguerre-Gaussian beams upon transmission
NASA Astrophysics Data System (ADS)
Prajapati, Chandravati
2017-04-01
We study numerically the spatial and angular contributions to Goos-Hänchen (GH) and Imbert-Fedorov (IF) shifts for higher-order (| l | ≥ 1) Laguerre-Gaussian (LG) beams upon transmission from a planar interface separating two media. Two kinds of spin-orbit interaction and their role in beam shifts are discussed. Firstly, the interaction between the spin and intrinsic orbital angular momentum (OAM) of the LG beam that produces polarization dependent angular shift which is further coupled to the angular momentum structure of the beam and gives rise to spatial shift in orthogonal direction. Secondly, the interaction between the intrinsic and extrinsic OAM of the beam which produces polarization independent transverse shift, called orbital-Hall effect (OHE). Since the angular and spatial shifts are coupled and the angular shift is dependent on the beam waist, the beam shifts can be tuned to maximize or reduce the resultant shifts for LG beams.
A comparison of different methods to implement higher order derivatives of density functionals
van Dam, Hubertus J.J.
2016-05-18
Density functional theory is the dominant approach in electronic structure methods today. To calculate properties higher order derivatives of the density functionals are required. These derivatives might be implemented manually,by automatic differentiation, or by symbolic algebra programs. Different authors have cited different reasons for using the particular method of their choice. This paper presents work where all three approaches were used and the strengths and weaknesses of each approach are considered. It is found that all three methods produce code that is suffficiently performanted for practical applications, despite the fact that our symbolic algebra generated code and our automatic differentiation code still have scope for significant optimization. The automatic differentiation approach is the best option for producing readable and maintainable code.
Higher-order mode analysis at the BNL Energy Recovery Linac
Johnson, E.C.; Ben-Zvi, I.; Hahn, H.; Hammons, L.; Xu, W.
2011-08-03
Understanding the prevalence and structure of higher-order modes (HOMs) in accelerator cavities is critical because their excitation can result in problematic single bunch and multi-bunch effects. Particularly hazardous are dipole modes, which are more easily excited due to their linear field nature near the beam center. During a recent superconducting test on the energy recovery linac (ERL) cavity at Brookhaven National Laboratory (BNL), 8 of the highest-Q HOMs were measured for the first time. In conjunction with analysis of CST Microwave Studio simulation results for the ERL model, one of these modes was further studied in the copper prototype ERL cavity. A method of identifying HOMs utilizing existing holes drilled in copper cavity cells was developed and used to conclude that the observed high-Q mode was a quadrupole.
NASA Astrophysics Data System (ADS)
Domin, Daniel S.
1999-01-01
The science laboratory instructional environment is ideal for fostering the development of problem-solving, manipulative, and higher-order thinking skills: the skills needed by today's learner to compete in an ever increasing technology-based society. This paper reports the results of a content analysis of ten general chemistry laboratory manuals. Three experiments from each manual were examined for evidence of higher-order cognitive activities. Analysis was based upon the six major cognitive categories of Bloom's Taxonomy of Educational Objectives: knowledge, comprehension, application, analysis, synthesis, and evaluation. The results of this study show that the overwhelming majority of general chemistry laboratory manuals provide tasks that require the use of only the lower-order cognitive skills: knowledge, comprehension, and application. Two of the laboratory manuals were disparate in having activities that utilized higher-order cognition. I describe the instructional strategies used within these manuals to foster higher-order cognitive development.
Accommodation with higher-order monochromatic aberrations corrected with adaptive optics
NASA Astrophysics Data System (ADS)
Chen, Li; Kruger, Philip B.; Hofer, Heidi; Singer, Ben; Williams, David R.
2006-01-01
Higher-order monochromatic aberrations in the human eye cause a difference in the appearance of stimuli at distances nearer and farther from best focus that could serve as a signed error signal for accommodation. We explored whether higher-order monochromatic aberrations affect the accommodative response to 0.5 D step changes in vergence in experiments in which these aberrations were either present as they normally are or removed with adaptive optics. Of six subjects, one could not accommodate at all for steps in either condition. One subject clearly required higher-order aberrations to accommodate at all. The remaining four subjects could accommodate in the correct direction even when higher-order aberrations were removed. No subjects improved their accommodation when higher-order aberrations were corrected, indicating that the corresponding decrease in the depth of field of the eye did not improve the accommodative response. These results are consistent with previous findings of large individual differences in the ability to accommodate in impoverished conditions. These results suggest that at least some subjects can use monochromatic higher-order aberrations to guide accommodation. They also show that some subjects can accommodate correctly when higher-order monochromatic aberrations as well as established cues to accommodation are greatly reduced.
Higher Order Pattern Structure Influences Auditory Representational Momentum
ERIC Educational Resources Information Center
Johnston, Heather Moynihan; Jones, Mari Riess
2006-01-01
Representational momentum refers to the phenomenon that observers tend to incorrectly remember an event undergoing real or implied motion as shifted beyond its actual final position. This has been demonstrated in both visual and auditory domains. In 5 pitch discrimination experiments, listeners heard tone sequences that implied either linear,…
NASA Astrophysics Data System (ADS)
Satvat, Nader
With the development of new core designs for generation IV reactors with their complexity and newer fuel designs, the need for consideration of neutron anisotropic scattering is becoming important for enchasing the economy and reliability of these designs. The theory and accurate modeling of neutron anisotropy is one of the most important problems of the transport solution to neutron Boltzmann equation. A number of methods based on careful theoretical developments, were established to numerically determine the effect of anisotropy; some of these methods are: the spherical harmonics method, the so-called function method (FN), the discrete ordinate method, and the Monte Carlo method. The AGENT methodology, based on the method of characteristics, currently the most accurate neutron transport method, represents the state-of-the-art advanced neutronics simulation tool available for 2D, 3D, and full core modeling. The higher order of anisotropic scattering (with no limitation of the number of expansion) is introduced into the AGENT code. An extensive analysis is performed to verify and validate this new model. It is shown that anisotropic scattering is important to be considered for complex geometries due to high angular dependence of neutron flux. The first principle in physics were used to explain the effects of anisotropic scattering (at the level on particle interactions), importance in including the higher moments in flux development for the core designs of high heterogonous structure promoting biased scattering (at the level of heterogeneous reactor assemblies in 2D and 3D). This inclusion of higher order of anisotropic scattering as expected increased the complexity of the mathematical model which in turn increased the computational time. An analysis of the computational time dependence on anisotropic scattering and the method of characteristics resolution parameters are analyzed with accurate predictions of scaling to larger geometries. Finally, an accelerated
Pulse transmission receiver with higher-order time derivative pulse correlator
Dress, Jr., William B.; Smith, Stephen F.
2003-09-16
Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a higher-order time derivative pulse correlator; a demodulation decoder coupled to the higher-order time derivative pulse correlator; a clock coupled to the demodulation decoder; and a pseudorandom polynomial generator coupled to both the higher-order time derivative pulse correlator and the clock. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.
Soliton solutions of the KdV equation with higher-order corrections
NASA Astrophysics Data System (ADS)
Wazwaz, Abdul-Majid
2010-10-01
In this work, the Korteweg-de Vries (KdV) equation with higher-order corrections is examined. We studied the KdV equation with first-order correction and that with second-order correction that include the terms of the fifth-order Lax, Sawada-Kotera and Caudrey-Dodd-Gibbon equations. The simplified form of the bilinear method was used to show the integrability of the first-order models and therefore to obtain multiple soliton solutions for each one. The obstacles to integrability of some of the models with second-order corrections are examined as well.
Structural Marginality and the Urban Social Order.
ERIC Educational Resources Information Center
Kapferer, Bruce
1978-01-01
This article argues for a redefinition of "Marginality" in terms of the principles that influence the developing order of the urban formation as a whole. The emerging social order and the political participation of residents of two shanty areas in Kabwe, Zambia are traced over a period of 40 years. (Author/EB)
NASA Astrophysics Data System (ADS)
Wen, Xiao-Yong; Yan, Zhenya
2017-02-01
The novel generalized perturbation (n, M)-fold Darboux transformations (DTs) are reported for the (2 + 1)-dimensional Kadomtsev-Petviashvili (KP) equation and its extension by using the Taylor expansion of the Darboux matrix. The generalized perturbation (1 , N - 1) -fold DTs are used to find their higher-order rational solitons and rogue wave solutions in terms of determinants. The dynamics behaviors of these rogue waves are discussed in detail for different parameters and time, which display the interesting RW and soliton structures including the triangle, pentagon, heptagon profiles, etc. Moreover, we find that a new phenomenon that the parameter (a) can control the wave structures of the KP equation from the higher-order rogue waves (a ≠ 0) into higher-order rational solitons (a = 0) in (x, t)-space with y = const . These results may predict the corresponding dynamical phenomena in the models of fluid mechanics and other physically relevant systems.
Huang, T W; Zhou, C T; He, X T
2013-05-01
Plasma defocusing and higher-order Kerr effects on multiple filamentation and pattern formation of ultrashort laser pulse propagation in air are investigated. Linear analyses and numerical results show that these two saturable nonlinear effects can destroy the coherent evolution of the laser field, and small-scale spatial turbulent structures rapidly appear. For the two-dimensional case, numerical simulations show that blow-up-like solutions, spatial chaos, and pseudorecurrence can appear at higher laser intensities if only plasma defocusing is included. These complex patterns result from the stochastic evolution of the higher- or shorter-wavelength modes of the laser light spectrum. From the viewpoint of nonlinear dynamics, filamentation can be attributed to the modulational instability of these spatial incoherent localized structures. Furthermore, filament patterns associated with multiphoton ionization of the air molecules with and without higher-order Kerr effects are compared.
Higher-order Peregrine combs and Peregrine walls for the variable-coefficient Lenells-Fokas equation
NASA Astrophysics Data System (ADS)
Wang, Zi-Qi; Wang, Xin; Wang, Lei; Sun, Wen-Rong; Qi, Feng-Hua
2017-02-01
In this paper, we study the variable-coefficient Lenells-Fokas (LF) model. Under large periodic modulations in the variable coefficients of the LF model, the generalized Akhmediev breathers develop into the breather multiple births (BMBs) from which we obtain the Peregrine combs (PCs). The PCs can be considered as the limiting case of the BMBs and be transformed into the Peregrine walls (PWs) with a specific amplitude of periodic modulation. We further investigate the spatiotemporal characteristics of the PCs and PWs analytically. Based on the second-order breather and rogue-wave solutions, we derive the corresponding higher-order structures (higher-order PCs and PWs) under proper periodic modulations. What is particularly noteworthy is that the second-order PC can be converted into the Peregrine pyramid which exhibits the higher amplitude and thickness. Our results could be helpful for the design of experiments in the optical fiber communications.
Zembrzycki, Andreas; Stocker, Adam M; Leingärtner, Axel; Sahara, Setsuko; Chou, Shen-Ju; Kalatsky, Valery; May, Scott R; Stryker, Michael P; O'Leary, Dennis DM
2015-01-01
In mammals, the neocortical layout consists of few modality-specific primary sensory areas and a multitude of higher order ones. Abnormal layout of cortical areas may disrupt sensory function and behavior. Developmental genetic mechanisms specify primary areas, but mechanisms influencing higher order area properties are unknown. By exploiting gain-of and loss-of function mouse models of the transcription factor Emx2, we have generated bi-directional changes in primary visual cortex size in vivo and have used it as a model to show a novel and prominent function for genetic mechanisms regulating primary visual area size and also proportionally dictating the sizes of surrounding higher order visual areas. This finding redefines the role for intrinsic genetic mechanisms to concomitantly specify and scale primary and related higher order sensory areas in a linear fashion. DOI: http://dx.doi.org/10.7554/eLife.11416.001 PMID:26705332
Higher-order corrections to dust ion-acoustic soliton in a quantum dusty plasma
Chatterjee, Prasanta; Das, Brindaban; Mondal, Ganesh; Muniandy, S. V.; Wong, C. S.
2010-10-15
Dust ion-acoustic soliton is studied in an electron-dust-ion plasma by employing a two-fluid quantum hydrodynamic model. Ions and electrons are assumed to follow quantum mechanical behaviors in dust background. The Korteweg-de Vries (KdV) equation and higher order contribution to KdV equations are derived using reductive perturbation technique. The higher order contribution is obtained as a higher order inhomogeneous differential equation. The nonsecular solution of the higher order contribution is obtained by using the renormalization method and the particular solution of the inhomogeneous equation is determined using a truncated series solution method. The effects of dust concentration, quantum parameter for ions and electrons, and soliton velocity on the amplitude and width of the dressed soliton are discussed.
Generalizing higher-order Bessel-Gauss beams: analytical description and demonstration.
Schimpf, Damian N; Schulte, Jan; Putnam, William P; Kärtner, Franz X
2012-11-19
We report on a novel class of higher-order Bessel-Gauss beams in which the well-known Bessel-Gauss beam is the fundamental mode and the azimuthally symmetric Laguerre-Gaussian beams are special cases. We find these higher-order Bessel-Gauss beams by superimposing decentered Hermite-Gaussian beams. We show analytically and experimentally that these higher-order Bessel-Gauss beams resemble higher-order eigenmodes of optical resonators consisting of aspheric mirrors. This work is relevant for the many applications of Bessel-Gauss beams in particular the more recently proposed high-intensity Bessel-Gauss enhancement cavities for strong-field physics applications.
Multiple sextupole system for the correction of third and higher order aberration
Crewe, Albert V.
1983-01-01
A means is provided for compensating for third and higher order aberration in charged particle beam devices. The means includes two sextupoles with an intermediate focusing lens, all positioned between two focusing lenses.
Obtaining tight bounds on higher-order interferences with a 5-path interferometer
NASA Astrophysics Data System (ADS)
Kauten, Thomas; Keil, Robert; Kaufmann, Thomas; Pressl, Benedikt; Brukner, Časlav; Weihs, Gregor
2017-03-01
Within the established theoretical framework of quantum mechanics, interference always occurs between pairs of paths through an interferometer. Higher order interferences with multiple constituents are excluded by Born’s rule and can only exist in generalized probabilistic theories. Thus, high-precision experiments searching for such higher order interferences are a powerful method to distinguish between quantum mechanics and more general theories. Here, we perform such a test in an optical multi-path interferometer, which avoids crucial systematic errors, has access to the entire phase space and is more stable than previous experiments. Our results are in accordance with quantum mechanics and rule out the existence of higher order interference terms in optical interferometry to an extent that is more than four orders of magnitude smaller than the expected pairwise interference, refining previous bounds by two orders of magnitude.
Regularity properties of fiber derivatives associated with higher-order mechanical systems
NASA Astrophysics Data System (ADS)
Colombo, Leonardo; Prieto-Martínez, Pedro Daniel
2016-08-01
The aim of this work is to study fiber derivatives associated to Lagrangian and Hamiltonian functions describing the dynamics of a higher-order autonomous dynamical system. More precisely, given a function in T∗T(k-1)Q, we find necessary and sufficient conditions for such a function to describe the dynamics of a kth-order autonomous dynamical system, thus being a kth-order Hamiltonian function. Then, we give a suitable definition of (hyper)regularity for these higher-order Hamiltonian functions in terms of their fiber derivative. In addition, we also study an alternative characterization of the dynamics in Lagrangian submanifolds in terms of the solutions of the higher-order Euler-Lagrange equations.
Das, Saptarshi; Saha, Suman; Das, Shantanu; Gupta, Amitava
2011-07-01
In this paper, a comparative study is done on the time and frequency domain tuning strategies for fractional order (FO) PID controllers to handle higher order processes. A new fractional order template for reduced parameter modelling of stable minimum/non-minimum phase higher order processes is introduced and its advantage in frequency domain tuning of FOPID controllers is also presented. The time domain optimal tuning of FOPID controllers have also been carried out to handle these higher order processes by performing optimization with various integral performance indices. The paper highlights on the practical control system implementation issues like flexibility of online autotuning, reduced control signal and actuator size, capability of measurement noise filtration, load disturbance suppression, robustness against parameter uncertainties etc. in light of the above tuning methodologies.
Bolognini, Gabriele; Bononi, Alberto
2009-04-27
We present a theoretical study of the performance of distributed Raman amplifiers with higher order pumping schemes, focusing in particular on double Rayleigh scattering (DRS) noise. Results show an unexpected significant DRS noise reduction for pumping order higher than third, allowing for an overall performance improvement of carefully designed distributed amplifiers, ensuring a large optical signal-to-noise ratio improvement together with reduced DRS-induced penalties.
Higher Order Convergence Rates in Theory of Homogenization: Equations of Non-divergence Form
NASA Astrophysics Data System (ADS)
Kim, Sunghan; Lee, Ki-Ahm
2016-03-01
We establish higher order convergence rates in the theory of periodic homogenization of both linear and fully nonlinear uniformly elliptic equations of non-divergence form. The rates are achieved by involving higher order correctors which fix the errors occurring both in the interior and on the boundary layer of our physical domain. The proof is based on a viscosity method and a new regularity theory which captures the stability of the correctors with respect to the shape of our limit profile.
Higher order mode of a microstripline fed cylindrical dielectric resonator antenna
NASA Astrophysics Data System (ADS)
Kumar, A. V. Praveen
2016-03-01
A microstrip transmission line can be used to excite the broadside radiating mode of a cylindrical dielectric resonator antenna (CDRA). The same is found to excite considerably well a higher order mode (HOM) as well. However unlike the broadside mode, the higher order mode gives distorted radiation pattern which makes this mode less useful for practical applications. The cause of distortion in the HOM radiation and the dependence of HOM coupling on the microstrip feed line are explored using HFSS simulations.
Study of higher order non-classical properties of squeezed Kerr state
NASA Astrophysics Data System (ADS)
Mishra, Devendra Kumar
2010-09-01
Recently, Prakash and Mishra [J. Phys. B: at. Mol. Opt. Phys., 39, 2291(2006); 40, 2531(2007)] have studied higher order sub-Poissonian photon statistic conditions for non-classicality in the form of general inequalities for expectation values of products of arbitrary powers of photon number and of photon-number fluctuation. It is, therefore, vital to study the generation of these higher order sub-Poissonian photon statistics (phase-insensitive behavior) in a physically realizable medium and their relations to higher order squeezing (phase-sensitive behavior). In the present paper, we study higher order non-classical properties, such as Hong and Mandel squeezing, amplitude-squared squeezing and higher order sub-Poissonian photon statistics, of squeezed Kerr state which is generated by squeezing the output of a Kerr medium whose input is coherent light. Such states can be realized if laser light is sent through an optical fiber and then into a degenerate parametric amplifier. It is established that the squeezed Kerr state can exhibit higher order non-classical properties.
Fast algorithm for scaling analysis with higher-order detrending moving average method
NASA Astrophysics Data System (ADS)
Tsujimoto, Yutaka; Miki, Yuki; Shimatani, Satoshi; Kiyono, Ken
2016-05-01
Among scaling analysis methods based on the root-mean-square deviation from the estimated trend, it has been demonstrated that centered detrending moving average (DMA) analysis with a simple moving average has good performance when characterizing long-range correlation or fractal scaling behavior. Furthermore, higher-order DMA has also been proposed; it is shown to have better detrending capabilities, removing higher-order polynomial trends than original DMA. However, a straightforward implementation of higher-order DMA requires a very high computational cost, which would prevent practical use of this method. To solve this issue, in this study, we introduce a fast algorithm for higher-order DMA, which consists of two techniques: (1) parallel translation of moving averaging windows by a fixed interval; (2) recurrence formulas for the calculation of summations. Our algorithm can significantly reduce computational cost. Monte Carlo experiments show that the computational time of our algorithm is approximately proportional to the data length, although that of the conventional algorithm is proportional to the square of the data length. The efficiency of our algorithm is also shown by a systematic study of the performance of higher-order DMA, such as the range of detectable scaling exponents and detrending capability for removing polynomial trends. In addition, through the analysis of heart-rate variability time series, we discuss possible applications of higher-order DMA.
Questions for assessing higher-order cognitive skills: it's not just Bloom's.
Lemons, Paula P; Lemons, J Derrick
2013-01-01
We present an exploratory study of biologists' ideas about higher-order cognition questions. We documented the conversations of biologists who were writing and reviewing a set of higher-order cognition questions. Using a qualitative approach, we identified the themes of these conversations. Biologists in our study used Bloom's Taxonomy to logically analyze questions. However, biologists were also concerned with question difficulty, the length of time required for students to address questions, and students' experience with questions. Finally, some biologists demonstrated an assumption that questions should have one correct answer, not multiple reasonable solutions; this assumption undermined their comfort with some higher-order cognition questions. We generated a framework for further research that provides an interpretation of participants' ideas about higher-order questions and a model of the relationships among these ideas. Two hypotheses emerge from this framework. First, we propose that biologists look for ways to measure difficulty when writing higher-order questions. Second, we propose that biologists' assumptions about the role of questions in student learning strongly influence the types of higher-order questions they write.
CuBIC: cumulant based inference of higher-order correlations in massively parallel spike trains
Rotter, Stefan; Grün, Sonja
2009-01-01
Recent developments in electrophysiological and optical recording techniques enable the simultaneous observation of large numbers of neurons. A meaningful interpretation of the resulting multivariate data, however, presents a serious challenge. In particular, the estimation of higher-order correlations that characterize the cooperative dynamics of groups of neurons is impeded by the combinatorial explosion of the parameter space. The resulting requirements with respect to sample size and recording time has rendered the detection of coordinated neuronal groups exceedingly difficult. Here we describe a novel approach to infer higher-order correlations in massively parallel spike trains that is less susceptible to these problems. Based on the superimposed activity of all recorded neurons, the cumulant-based inference of higher-order correlations (CuBIC) presented here exploits the fact that the absence of higher-order correlations imposes also strong constraints on correlations of lower order. Thus, estimates of only few lower-order cumulants suffice to infer higher-order correlations in the population. As a consequence, CuBIC is much better compatible with the constraints of in vivo recordings than previous approaches, which is shown by a systematic analysis of its parameter dependence. PMID:19862611
Model predictions of higher-order normal alkane ignition from dilute shock-tube experiments
NASA Astrophysics Data System (ADS)
Rotavera, B.; Petersen, E. L.
2013-07-01
Shock-induced oxidation of two higher-order linear alkanes was measured using a heated shock tube facility. Experimental overlap in stoichiometric ignition delay times obtained under dilute (99 % Ar) conditions near atmospheric pressure was observed in the temperature-dependent ignition trends of n-nonane ( n-C9H20) and n-undecane ( n-C11H24). Despite the overlap, model predictions of ignition using two different detailed chemical kinetics mechanisms show discrepancies relative to both the measured data as well as to one another. The present study therefore focuses on the differences observed in the modeled, high-temperature ignition delay times of higher-order n-alkanes, which are generally regarded to have identical ignition behavior for carbon numbers above C7. Comparisons are drawn using experimental data from the present study and from recent work by the authors relative to two existing chemical kinetics mechanisms. Time histories from the shock-tube OH* measurements are also compared to the model predictions; a double-peaked structure observed in the data shows that the time response of the detector electronics is crucial for properly capturing the first, incipient peak near time zero. Calculations using the two mechanisms were carried out at the dilution level employed in the shock-tube experiments for lean {({φ} = 0.5)}, stoichiometric, and rich {({φ} = 2.0)} equivalence ratios, 1230-1620 K, and for both 1.5 and 10 atm. In general, the models show differing trends relative to both measured data and to one another, indicating that agreement among chemical kinetics models for higher-order n-alkanes is not consistent. For example, under certain conditions, one mechanism predicts the ignition delay times to be virtually identical between the n-nonane and n-undecane fuels (in fact, also for all alkanes between at least C8 and C12), which is in agreement with the experiment, while the other mechanism predicts the larger fuels to ignite progressively more slowly.
Numerical simulation of stratified shear flow using a higher order Taylor series expansion method
Iwashige, Kengo; Ikeda, Takashi
1995-09-01
A higher order Taylor series expansion method is applied to two-dimensional numerical simulation of stratified shear flow. In the present study, central difference scheme-like method is adopted for an even expansion order, and upwind difference scheme-like method is adopted for an odd order, and the expansion order is variable. To evaluate the effects of expansion order upon the numerical results, a stratified shear flow test in a rectangular channel (Reynolds number = 1.7x10{sup 4}) is carried out, and the numerical velocity and temperature fields are compared with experimental results measured by laser Doppler velocimetry thermocouples. The results confirm that the higher and odd order methods can simulate mean velocity distributions, root-mean-square velocity fluctuations, Reynolds stress, temperature distributions, and root-mean-square temperature fluctuations.
Higher-order interference of low-coherence optical fiber sensors.
Yang, Jun; Yuan, Yonggui; Wu, Bing; Zhou, Ai; Yuan, Libo
2011-09-01
The higher-order interference noise that is caused by multireflection at the fiber sensor's end surface in low-coherence fiber sensor array is proposed. The generation of the higher-order interference noise and its quantity and amplitude are theoretically analyzed. The second-order interference noises are experimentally demonstrated. The results show that the second-order noises arise in any sensor array composed of more than two sensors and the number of the second-order peaks is proportional to the third power of the sensor's number. The ratio of the amplitude of the second-order noise to that of the signal peak is proportional to the reflectivity of the sensor's end surface. In a sensor array, when the reflectivity is more than 10(-5), the amplitude of the second-order noise is higher than other noises and it becomes a main factor that determines the signal-to-noise ratio of the sensor arrays. Therefore, reducing the higher-order interference noise can improve the multiplexing capacity of the sensor array.
Higher Order Cumulant Studies of Ocean Surface Random Fields from Satellite Altimeter Data
NASA Technical Reports Server (NTRS)
Cheng, B.
1996-01-01
Higher order statistics, especially 2nd order statistics, have been used to study ocean processes for many years in the past, and occupy an appreciable part of the research literature on physical oceanography. They in turn form part of a much larger field of study in statistical fluid mechanics.
ERIC Educational Resources Information Center
Toledo, Santiago; Dubas, Justin M.
2016-01-01
An emphasis on higher-order thinking within the curriculum has been a subject of interest in the chemical and STEM literature due to its ability to promote meaningful, transferable learning in students. The systematic use of learning taxonomies could be a practical way to scaffold student learning in order to achieve this goal. This work proposes…
ERIC Educational Resources Information Center
Scandura, Joseph M.; And Others
The research reported in this paper was designed to analyze the incidence of use of higher-order rules by students solving geometric construction problems. A carefully selected set of construction problems was subjected to rigorous a priori analysis by mathematics educators to determine what basic and second-order rules might be used by able high…
Higher Order, Critical Thinking Skills in National Police Academy Course Development
ERIC Educational Resources Information Center
Barker, Beth A.
2011-01-01
Law enforcement requires the officer to invoke reason and critical thinking skills in order to solve intricate problems in real time, on the job. This study examined the course development of a large national organization (State Police Academies) to ascertain what strategies are being used in their courses to promote training for higher order,…
A wireless and passive pressure sensor system based on the magnetic higher-order harmonic field
NASA Astrophysics Data System (ADS)
Tan, Ee Lim
The goal of this work is to develop a magnetic-based passive and wireless pressure sensor for use in biomedical applications. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is composed of two magnetic elements: a magnetically-soft material acts as a sensing element, and a magnetically hard material acts as a biasing element. Both elements are embedded within a rigid sensor body and sealed with an elastomer pressure membrane. Upon excitation of an externally applied AC magnetic field, the sensing element is capable of producing higher-order magnetic signature that is able to be remotely detected with an external receiving coil. When exposed to environment with changing ambient pressure, the elastomer pressure membrane of pressure sensor is deflected depending on the surrounding pressure. The deflection of elastomer membrane changes the separation distance between the sensing and biasing elements. As a result, the higher-order harmonic signal emitted by the magnetically-soft sensing element is shifted, allowing detection of pressure change by determining the extent of the harmonic shifting. The passive and wireless nature of the sensor is enabled with an external excitation and receiving system consisting of an excitation coil and a receiving coil. These unique characteristics made the sensor suitable to be used for continuous and long-term pressure monitoring, particularly useful for biomedical applications which often require frequent surveillance. In this work, abdominal aortic aneurysm is selected as the disease model for evaluation the performance of pressure sensor and system. Animal model, with subcutaneous sensor implantation in mice, was conducted to demonstrate the efficacy and feasibility of pressure sensor in biological environment.
ERIC Educational Resources Information Center
Gamino, Jacquelyn F.; Chapman, Sandra B.; Cook, Lori G.
2009-01-01
Little is known about strategic learning ability in preteens and adolescents with traumatic brain injury (TBI). Strategic learning is the ability to combine and synthesize details to form abstracted gist-based meanings, a higher-order cognitive skill associated with frontal lobe functions and higher classroom performance. Summarization tasks were…
Higher Education and the New International Order. A Collection of Papers.
ERIC Educational Resources Information Center
Sanyal, Bikas C., Ed.
Addressing the issues surrounding the relationship between higher education and the development of a new international economic order, the 11 articles collected here provide an introductory analysis of the current relationship between higher education and the world economy, analyze the differing needs of developing and developed countries, and…
Nonlinear Dynamic Stability of the Viscoelastic Plate Considering Higher Order Modes
NASA Astrophysics Data System (ADS)
Sun, Yuanxiang; Wang, Cheng
2016-11-01
-The dynamic stability of viscoelastic plates is investigated in this paper by using chaotic and fractal theory. The nonlinear integro-differential dynamic equation is changed into an autonomic 4-dimensional dynamical system. The numerical time integrations of equations are obtained by using the fourth order Runge-Kutta method. And the Lyapunov exponent spectrum, the fractal dimension of strange attractors and the time evolution of deflection are obtained. The influence of viscoelastic parameter on dynamic buckling of viscoelastic plates is discussed. The effect of higher order modes on dynamic stability of viscoelastic plate is obtained, the necessity of considering higher order modes is discussed.
NASA Technical Reports Server (NTRS)
Heyman, J. S.; Allison, S. G.; Salama, K.
1985-01-01
The behavior of higher order elastic properties, which are much more sensitive to material state than are second order properties, has been studied for steel alloys AISI 1016, 1045, 1095, and 8620 by measuring the stress derivative of the acoustic natural velocity to determine the stress acoustic constants (SAC's). Results of these tests show a 20 percent linear variation of SAC's with carbon content as well as even larger variations with prestrain (plastic deformation). The use of higher order elastic characterization permits quantitative evaluation of solids and may prove useful in studies of fatigue and fracture.
Marquette, Ian
2010-07-15
We construct integrals of motion for multidimensional classical systems from ladder operators of one-dimensional systems. This method can be used to obtain new systems with higher order integrals. We show how these integrals generate a polynomial Poisson algebra. We consider a one-dimensional system with third order ladder operators and found a family of superintegrable systems with higher order integrals of motion. We obtain also the polynomial algebra generated by these integrals. We calculate numerically the trajectories and show that all bounded trajectories are closed.
Higher Order Modeling in Hybrid Approaches to the Computation of Electromagnetic Fields
NASA Technical Reports Server (NTRS)
Wilton, Donald R.; Fink, Patrick W.; Graglia, Roberto D.
2000-01-01
Higher order geometry representations and interpolatory basis functions for computational electromagnetics are reviewed. Two types of vector-valued basis functions are described: curl-conforming bases, used primarily in finite element solutions, and divergence-conforming bases used primarily in integral equation formulations. Both sets satisfy Nedelec constraints, which optimally reduce the number of degrees of freedom required for a given order. Results are presented illustrating the improved accuracy and convergence properties of higher order representations for hybrid integral equation and finite element methods.
A single dose of oxytocin nasal spray improves higher-order social cognition in schizophrenia.
Guastella, Adam J; Ward, Philip B; Hickie, Ian B; Shahrestani, Sara; Hodge, Marie Antoinette Redoblado; Scott, Elizabeth M; Langdon, Robyn
2015-11-01
Schizophrenia is associated with significant impairments in both higher and lower order social cognitive performance and these impairments contribute to poor social functioning. People with schizophrenia report poor social functioning to be one of their greatest unmet treatment needs. Recent studies have suggested the potential of oxytocin as such a treatment, but mixed results render it uncertain what aspects of social cognition are improved by oxytocin and, subsequently, how oxytocin might best be applied as a therapeutic. The aim of this study was to determine whether a single dose of oxytocin improved higher-order and lower-order social cognition performance for patients with schizophrenia across a well-established battery of social cognition tests. Twenty-one male patients received both a single dose of oxytocin nasal spray (24IU) and a placebo, two weeks apart in a randomized within-subjects placebo controlled design. Following each administration, participants completed the social cognition tasks, as well as a test of general neurocognition. Results revealed that oxytocin particularly enhanced performance on higher order social cognition tasks, with no effects on general neurocognition. Results for individual tasks showed most improvement on tests measuring appreciation of indirect hints and recognition of social faux pas. These results suggest that oxytocin, if combined to enhance social cognition learning, may be beneficial when targeted at higher order social cognition domains. This study also suggests that these higher order tasks, which assess social cognitive processing in a social communication context, may provide useful markers of response to oxytocin in schizophrenia.
An efficient higher-order PML in WLP-FDTD method for time reversed wave simulation
NASA Astrophysics Data System (ADS)
Wei, Xiao-Kun; Shao, Wei; Ou, Haiyan; Wang, Bing-Zhong
2016-09-01
Derived from a stretched coordinate formulation, a higher-order complex frequency shifted (CFS) perfectly matched layer (PML) is proposed for the unconditionally stable finite-difference time-domain (FDTD) method based on weighted Laguerre polynomials (WLPs). The higher-order PML is implemented with an auxiliary differential equation (ADE) approach. In order to further improve absorbing performance, the parameter values of stretching functions in the higher-order PML are optimized by the multi-objective genetic algorithm (MOGA). The optimal solutions can be chosen from the Pareto front for trading-off between two independent objectives. It is shown in a numerical test that the higher-order PML is efficient in terms of attenuating propagating waves and reducing late time reflections. Moreover, the higher-order PML can be placed very close to the wall when analyzing the channel characteristics of time reversal (TR) waves in a multipath indoor environment. Numerical examples of TR wave propagation demonstrate the availability of the proposed method.
Design and Application of Strategies/Tactics in Higher Order Logics
NASA Technical Reports Server (NTRS)
Archer, Myla (Editor); diVito, Ben (Editor); Munoz, Cesar (Editor)
2003-01-01
This Proceedings includes both a paper from the implementors of PVS providing guidance for PVS strategy writers and a tutorial on PVS strategy writing distilled from the experience of three PVS users who have written extensive sets of PVS user strategies. Following these are three full papers from the higher-order logic theorem proving community that discuss PVS strategies to enhance arithmetic and other interactive reasoning in PVS; implementing first-order tactics in higher-order provers; and a proposed technique for specifying small step semantics that can be used in multiple higher order logic theorem provers, with illustrations from both Coq and PVS. The Proceedings concludes with three position papers for a panel session that discuss three settings in which development of PVS strategies is worth while.
Higher-order cumulants and spectral kurtosis for early detection of subterranean termites
NASA Astrophysics Data System (ADS)
de la Rosa, Juan José González; Moreno Muñoz, Antonio
2008-02-01
This paper deals with termite detection in non-favorable SNR scenarios via signal processing using higher-order statistics. The results could be extrapolated to all impulse-like insect emissions; the situation involves non-destructive termite detection. Fourth-order cumulants in time and frequency domains enhance the detection and complete the characterization of termite emissions, non-Gaussian in essence. Sliding higher-order cumulants offer distinctive time instances, as a complement to the sliding variance, which only reveal power excesses in the signal; even for low-amplitude impulses. The spectral kurtosis reveals non-Gaussian characteristics (the peakedness of the probability density function) associated to these non-stationary measurements, specially in the near ultrasound frequency band. Contrasted estimators have been used to compute the higher-order statistics. The inedited findings are shown via graphical examples.
Quasi suppression of higher-order diffractions with inclined rectangular apertures gratings
NASA Astrophysics Data System (ADS)
Liu, Yuwei; Zhu, Xiaoli; Gao, Yulin; Zhang, Wenhai; Fan, Quanping; Wei, Lai; Yang, Zuhua; Zhang, Qiangqiang; Qian, Feng; Chen, Yong; He, Weihua; Wu, Yinzhong; Yan, Zhuoyang; Hua, Yilei; Zhao, Yidong; Cui, Mingqi; Qiu, Rong; Zhou, Weimin; Gu, Yuqiu; Zhang, Baohan; Xie, Changqing; Cao, Leifeng
2015-11-01
Advances in the fundamentals and applications of diffraction gratings have received much attention. However, conventional diffraction gratings often suffer from higher-order diffraction contamination. Here, we introduce a simple and compact single optical element, named inclined rectangular aperture gratings (IRAG), for quasi suppression of higher-order diffractions. We show, both in the visible light and soft x-ray regions, that IRAG can significantly suppress higher-order diffractions with moderate diffraction efficiency. Especially, as no support strut is needed to maintain the free-standing patterns, the IRAG is highly advantageous to the extreme-ultraviolet and soft x-ray regions. The diffraction efficiency of the IRAG and the influences of fabrication constraints are also discussed. The unique quasi-single order diffraction properties of IRAG may open the door to a wide range of photonic applications.
A Higher-Order Boundary Treatment for Cartesian-Grid Methods
NASA Astrophysics Data System (ADS)
Forrer, Hans; Jeltsch, Rolf
1998-03-01
The Euler equations describe the flow phenomena of compressible inviscid gas dynamics. We simulate such flows using a higher-order Cartesian-grid method, together with a special treatment for the cells cut by the boundary of an object. A new method for the treatment of the boundary is described where these cut boundary cells are maintained as whole cells rather than as cut cells, thus avoiding stability problems. The method is second-order accurate in one dimension and higher-order accurate in two dimensions but not strictly conservative; however, we show that this error in the conservation does not lead to spurious phenomena on some representative test calculations. The advantages of the new boundary treatment are that it is higher-order accurate, that it is independent of the applied method, and that it is simple.
Quasi suppression of higher-order diffractions with inclined rectangular apertures gratings
Liu, Yuwei; Zhu, Xiaoli; Gao, Yulin; Zhang, Wenhai; Fan, Quanping; Wei, Lai; Yang, Zuhua; Zhang, Qiangqiang; Qian, Feng; Chen, Yong; He, Weihua; Wu, Yinzhong; Yan, Zhuoyang; Hua, Yilei; Zhao, Yidong; Cui, Mingqi; Qiu, Rong; Zhou, Weimin; Gu, Yuqiu; Zhang, Baohan; Xie, Changqing; Cao, Leifeng
2015-01-01
Advances in the fundamentals and applications of diffraction gratings have received much attention. However, conventional diffraction gratings often suffer from higher-order diffraction contamination. Here, we introduce a simple and compact single optical element, named inclined rectangular aperture gratings (IRAG), for quasi suppression of higher-order diffractions. We show, both in the visible light and soft x-ray regions, that IRAG can significantly suppress higher-order diffractions with moderate diffraction efficiency. Especially, as no support strut is needed to maintain the free-standing patterns, the IRAG is highly advantageous to the extreme-ultraviolet and soft x-ray regions. The diffraction efficiency of the IRAG and the influences of fabrication constraints are also discussed. The unique quasi-single order diffraction properties of IRAG may open the door to a wide range of photonic applications. PMID:26563588
Critical study of higher order numerical methods for solving the boundary-layer equations
NASA Technical Reports Server (NTRS)
Wornom, S. F.
1978-01-01
A fourth order box method is presented for calculating numerical solutions to parabolic, partial differential equations in two variables or ordinary differential equations. The method, which is the natural extension of the second order box scheme to fourth order, was demonstrated with application to the incompressible, laminar and turbulent, boundary layer equations. The efficiency of the present method is compared with two point and three point higher order methods, namely, the Keller box scheme with Richardson extrapolation, the method of deferred corrections, a three point spline method, and a modified finite element method. For equivalent accuracy, numerical results show the present method to be more efficient than higher order methods for both laminar and turbulent flows.
A critical study of higher-order numerical methods for solving the boundary-layer equations
NASA Technical Reports Server (NTRS)
Wornom, S. F.
1977-01-01
A fourth-order box method is presented for calculating numerical solutions to parabolic, partial differential equations in two variables or ordinary differential equations. The method is the natural extension of the second-order Keller Box Scheme to fourth order and is demonstrated with application to the incompressible, laminar and turbulent boundary-layer equations. The efficiency of the present method is compared with other two-point and three-point higher-order methods; namely, the Keller Box Scheme with Richardson extrapolation, the method of deferred corrections, and the three-point spline methods. For equivalent accuracy, numerical results show the present method to be more efficient than the other higher-order methods for both laminar and turbulent flows.
Application of higher-order numerical methods to the boundary-layer equations
NASA Technical Reports Server (NTRS)
Wornom, S. F.
1978-01-01
A fourth-order method is presented for calculating numerical solutions to parabolic, partial differential equations in two variables or ordinary differential equations. The method is the natural extension of the second-order Keller Box Scheme to fourth order and is demonstrated with application to the incompressible, laminar and turbulent boundary-layer equations for both attached and separated flows. The efficiency of the present method is compared with other higher-order methods; namely, the Keller Box Scheme with Richardson extrapolation, the method of deferred corrections, the three-point spline methods, and a modified finite-element method. For equivalent accuracy, numerical results show the present method to be more efficient than the other higher-order methods for both laminar and turbulent flows.
Tuning PID controllers for higher-order oscillatory systems with improved performance.
Malwatkar, G M; Sonawane, S H; Waghmare, L M
2009-07-01
In this paper, model based design of PID controllers is proposed for higher-order oscillatory systems. The proposed method has no limitations regarding systems order, time delays and oscillatory behavior. The reduced model is achieved based on third-order modeling and selection of coefficients through the use of frequency responses. The tuning of the PID parameters are obtained from a reduced third-order model; the procedure seems to be simple and effective, and improved performance of the overall system can be achieved. Three simulation examples and one real-time experiment are included to demonstrate the effectiveness and applicability of the proposed method to systems with oscillatory behavior.
Performance of Higher Order Campbell methods, Part II: calibration and experimental application
NASA Astrophysics Data System (ADS)
Elter, Zs.; de Izarra, G.; Filliatre, P.; Jammes, C.; Pázsit, I.
2016-11-01
Applying Higher Order Campbelling methods in neutron flux monitoring with fission chambers is advantageous due to their capabilities to suppress the impact of unwanted noises and signal contributions (such as gamma radiation). This work aims to verify through experimental results that the basic assumptions behind the Higher Order Campelling methods are valid in critical reactors. The experiments, reported in this work, were performed at the MINERVE reactor in Cadarache. It is shown that the calibration of a fission chamber and the associated electronic system is possible in higher order mode. With the use of unbiased cumulant estimators and with digital processing, it is shown that over a wide count rate range, accurate count rate estimation can be achieved based on signal samples of a few ms, which is a significant progress compared to similar experimental results in the literature. The difference between the count rate estimated by pulse counting and by the Higher Order Campelling is less than 4%. The work also investigates the possibility of monitoring transient events. For this purpose, a control rod drop event was followed in Higher Order Campbelling mode.
Application of higher order statistics/spectra in biomedical signals--a review.
Chua, Kuang Chua; Chandran, Vinod; Acharya, U Rajendra; Lim, Choo Min
2010-09-01
For many decades correlation and power spectrum have been primary tools for digital signal processing applications in the biomedical area. The information contained in the power spectrum is essentially that of the autocorrelation sequence; which is sufficient for complete statistical descriptions of Gaussian signals of known means. However, there are practical situations where one needs to look beyond autocorrelation of a signal to extract information regarding deviation from Gaussianity and the presence of phase relations. Higher order spectra, also known as polyspectra, are spectral representations of higher order statistics, i.e. moments and cumulants of third order and beyond. HOS (higher order statistics or higher order spectra) can detect deviations from linearity, stationarity or Gaussianity in the signal. Most of the biomedical signals are non-linear, non-stationary and non-Gaussian in nature and therefore it can be more advantageous to analyze them with HOS compared to the use of second-order correlations and power spectra. In this paper we have discussed the application of HOS for different bio-signals. HOS methods of analysis are explained using a typical heart rate variability (HRV) signal and applications to other signals are reviewed.
Analysis of warping deformation modes using higher order ANCF beam element
NASA Astrophysics Data System (ADS)
Orzechowski, Grzegorz; Shabana, Ahmed A.
2016-02-01
Most classical beam theories assume that the beam cross section remains a rigid surface under an arbitrary loading condition. However, in the absolute nodal coordinate formulation (ANCF) continuum-based beams, this assumption can be relaxed allowing for capturing deformation modes that couple the cross-section deformation and beam bending, torsion, and/or elongation. The deformation modes captured by ANCF finite elements depend on the interpolating polynomials used. The most widely used spatial ANCF beam element employs linear approximation in the transverse direction, thereby restricting the cross section deformation and leading to locking problems. The objective of this investigation is to examine the behavior of a higher order ANCF beam element that includes quadratic interpolation in the transverse directions. This higher order element allows capturing warping and non-uniform stretching distribution. Furthermore, this higher order element allows for increasing the degree of continuity at the element interface. It is shown in this paper that the higher order ANCF beam element can be used effectively to capture warping and eliminate Poisson locking that characterizes lower order ANCF finite elements. It is also shown that increasing the degree of continuity requires a special attention in order to have acceptable results. Because higher order elements can be more computationally expensive than the lower order elements, the use of reduced integration for evaluating the stress forces and the use of explicit and implicit numerical integrations to solve the nonlinear dynamic equations of motion are investigated in this paper. It is shown that the use of some of these integration methods can be very effective in reducing the CPU time without adversely affecting the solution accuracy.
NASA Astrophysics Data System (ADS)
Srzic, Veljko; Gotovac, Hrvoje; Cvetkovic, Vladimir; Andricevic, Roko
2014-05-01
In this work Langrangian framework is used for conservative tracer transport simulations through 2-D extremely heterogeneous porous media. Conducted numerical simulations enable large sets of concentration values in both spatial and temporal domains. In addition to the advection, which acts on all scales, an additional mechanism considered is local scale dispersion (LSD), accounting for both mechanical dispersion and molecular diffusion. The ratio between these two mechanisms is quantified by the Peclet (Pe) number. In its base, the work gives answers to concentration scalar features when influenced by: i) different log-conductivity variance; ii) log-conductivity structures defined by the same global variogram but with different log conductivity patterns correlated; and iii) for a wide range of Peclet values. Results conducted by Monte Carlo analysis show a complex interplay between the aforementioned parameters, indicating the influence of aquifer properties to temporal LSD evolution. A remarkable collapse of higher order to second-order concentration moments [Yee, 2009] leads to the conclusion that only two concentration moments are required for an accurate description of concentration fluctuations. This explicitly holds for the pure advection case, while in the case of LSD presence the moment deriving function(MDF) is involved to ensure the moment collapse validity. An inspection of the Beta distribution leads to the conclusion that the two-parametric distribution can be used for concentration fluctuation characterization even in cases of high aquifer heterogeneity and/or for different log-conductivity structures, independent of the sampling volume used. Furthermore, the expected mass fraction (EMF) [Heagy & Sullivan, 1996] concept is applied in groundwater transport. In its origin, EMF is function of the concentration but with lower number of realizations needed for its determination, compared to the one point PDF. From practical point of view, EMF excludes
3D Higher Order Modeling in the BEM/FEM Hybrid Formulation
NASA Technical Reports Server (NTRS)
Fink, P. W.; Wilton, D. R.
2000-01-01
Higher order divergence- and curl-conforming bases have been shown to provide significant benefits, in both convergence rate and accuracy, in the 2D hybrid finite element/boundary element formulation (P. Fink and D. Wilton, National Radio Science Meeting, Boulder, CO, Jan. 2000). A critical issue in achieving the potential for accuracy of the approach is the accurate evaluation of all matrix elements. These involve products of high order polynomials and, in some instances, singular Green's functions. In the 2D formulation, the use of a generalized Gaussian quadrature method was found to greatly facilitate the computation and to improve the accuracy of the boundary integral equation self-terms. In this paper, a 3D, hybrid electric field formulation employing higher order bases and higher order elements is presented. The improvements in convergence rate and accuracy, compared to those resulting from lower order modeling, are established. Techniques developed to facilitate the computation of the boundary integral self-terms are also shown to improve the accuracy of these terms. Finally, simple preconditioning techniques are used in conjunction with iterative solution procedures to solve the resulting linear system efficiently. In order to handle the boundary integral singularities in the 3D formulation, the parent element- either a triangle or rectangle-is subdivided into a set of sub-triangles with a common vertex at the singularity. The contribution to the integral from each of the sub-triangles is computed using the Duffy transformation to remove the singularity. This method is shown to greatly facilitate t'pe self-term computation when the bases are of higher order. In addition, the sub-triangles can be further divided to achieve near arbitrary accuracy in the self-term computation. An efficient method for subdividing the parent element is presented. The accuracy obtained using higher order bases is compared to that obtained using lower order bases when the number
Investigating higher order modes effects on thermionic RF gun transverse emittance
NASA Astrophysics Data System (ADS)
Rajabi, A.; Shokri, B.; Feghhi, S. A. H.
2017-02-01
As the excitation of higher order modes in high gradient accelerating cavities of the RF gun negatively influences electron beam quality, in the present work a theory is obtained based on generalizing Panofsky-Wenzel theorem to study the effect of transverse magnetic modes on transverse emittance growth of the RF gun. Based on this theory, the impact of higher order modes on transverse momentum is investigated. Based on analysis and simulation results, it is shown that different RF modes result in divergence or convergence effects on beam transverse dynamics. The presence of dipole and quadrupole modes can enhance the transverse emittance by 320 % and 450 % , respectively. The compound effect of the presence of two higher order modes results in 470 % transverse emittance growth.
Collocated electrodynamic FDTD schemes using overlapping Yee grids and higher-order Hodge duals
NASA Astrophysics Data System (ADS)
Deimert, C.; Potter, M. E.; Okoniewski, M.
2016-12-01
The collocated Lebedev grid has previously been proposed as an alternative to the Yee grid for electromagnetic finite-difference time-domain (FDTD) simulations. While it performs better in anisotropic media, it performs poorly in isotropic media because it is equivalent to four overlapping, uncoupled Yee grids. We propose to couple the four Yee grids and fix the Lebedev method using discrete exterior calculus (DEC) with higher-order Hodge duals. We find that higher-order Hodge duals do improve the performance of the Lebedev grid, but they also improve the Yee grid by a similar amount. The effectiveness of coupling overlapping Yee grids with a higher-order Hodge dual is thus questionable. However, the theoretical foundations developed to derive these methods may be of interest in other problems.
Development of a Higher Order Laminate Theory for Modeling Composites with Induced Strain Actuators
NASA Technical Reports Server (NTRS)
Chattopadhyay, Aditi; Seeley, Charles E.
1996-01-01
A refined higher order plate theory is developed to investigate the actuation mechanism of piezoelectric materials surface bonded or embedded in composite laminates. The current analysis uses a displacement field which accurately accounts for transverse shear stresses. Some higher order terms are identified by using the conditions that shear stresses vanish at all free surfaces. Therefore, all boundary conditions for displacements and stresses are satisfied in the present theory. The analysis is implemented using the finite element method which provides a convenient means to construct a numerical solution due to the discrete nature of the actuators. The higher order theory is computationally less expensive than a full three dimensional analysis. The theory is also shown to agree well with published experimental results. Numerical examples are presented for composite plates with thicknesses ranging from thin to very thick.
A higher order visual neuron tuned to the spatial amplitude spectra of natural scenes
Dyakova, Olga; Lee, Yu-Jen; Longden, Kit D.; Kiselev, Valerij G.; Nordström, Karin
2015-01-01
Animal sensory systems are optimally adapted to those features typically encountered in natural surrounds, thus allowing neurons with limited bandwidth to encode challengingly large input ranges. Natural scenes are not random, and peripheral visual systems in vertebrates and insects have evolved to respond efficiently to their typical spatial statistics. The mammalian visual cortex is also tuned to natural spatial statistics, but less is known about coding in higher order neurons in insects. To redress this we here record intracellularly from a higher order visual neuron in the hoverfly. We show that the cSIFE neuron, which is inhibited by stationary images, is maximally inhibited when the slope constant of the amplitude spectrum is close to the mean in natural scenes. The behavioural optomotor response is also strongest to images with naturalistic image statistics. Our results thus reveal a close coupling between the inherent statistics of natural scenes and higher order visual processing in insects. PMID:26439748
The Analysis of Thin Wires Using Higher-Order Elements and Basis Functions
Champagne, N J; Wilton, D R; Rockway, J W
2006-01-23
Thin wire analysis was applied to curved wire segments in [1], but a special procedure was needed to evaluate the self and near-self terms. The procedure involved associating the singular behavior with a straight segment tangent to the curved source segment, permitting use of algorithms for straight wires. Recently, a procedure that avoids the singularity extraction for straight wires was presented in [2-4]. In this paper, the approach in [4] is applied to curved (or higher-order) wires using a procedure similar to that used in [1] for singularity extraction. Here, the straight tangent segment is used to determine the quadrature rules to be used on the curved segment. The result is a formulation that allows for a general mixture of higher-order basis functions [5] and higher-order wire segments.
A new fuzzy multi-objective higher order moment portfolio selection model for diversified portfolios
NASA Astrophysics Data System (ADS)
Yue, Wei; Wang, Yuping
2017-01-01
Due to the important effect of the higher order moments to portfolio returns, the aim of this paper is to make use of the third and fourth moments for fuzzy multi-objective portfolio selection model. Firstly, in order to overcome the low diversity of the obtained solution set and lead to corner solutions for the conventional higher moment portfolio selection models, a new entropy function based on Minkowski measure is proposed as a new objective function and a novel fuzzy multi-objective weighted possibilistic higher order moment portfolio model is presented. Secondly, to solve the proposed model efficiently, a new multi-objective evolutionary algorithm is designed. Thirdly, several portfolio performance evaluation techniques are used to evaluate the performance of the portfolio models. Finally, some experiments are conducted by using the data of Shanghai Stock Exchange and the results indicate the efficiency and effectiveness of the proposed model and algorithm.
Analytical investigation of higher-order plasmonic modes on a metal-dielectric interface
NASA Astrophysics Data System (ADS)
Kordi, Mahdi; Armin, Fahimeh; Malekfar, Mohammad R.; Mirsalehi, Mir Mojtaba; Shokooh-Saremi, Mehrdad
2017-03-01
Based on the plane-wave expansion method, we have analytically obtained a set of higher-order transverse magnetic (TM) modes that can exist on a metal-dielectric interface. Any linear combination of these modes can be supported on the interface. Our analysis is based on the assumption of nonuniformity of the electromagnetic fields in all directions. We have also shown that no higher-order transverse electric (TE) mode can propagate on the interface. Furthermore, the orientation of Poynting vector and energy flow of the TM modes are described. Our results show that the Poynting vector of a higher-order TM mode always makes an angle with the interface, which means TM modes are not pure surface waves.
NASA Astrophysics Data System (ADS)
Afra, Sardar; Gildin, Eduardo
2016-09-01
Parameter estimation through robust parameterization techniques has been addressed in many works associated with history matching and inverse problems. Reservoir models are in general complex, nonlinear, and large-scale with respect to the large number of states and unknown parameters. Thus, having a practical approach to replace the original set of highly correlated unknown parameters with non-correlated set of lower dimensionality, that captures the most significant features comparing to the original set, is of high importance. Furthermore, de-correlating system's parameters while keeping the geological description intact is critical to control the ill-posedness nature of such problems. We introduce the advantages of a new low dimensional parameterization approach for reservoir characterization applications utilizing multilinear algebra based techniques like higher order singular value decomposition (HOSVD). In tensor based approaches like HOSVD, 2D permeability images are treated as they are, i.e., the data structure is kept as it is, whereas in conventional dimensionality reduction algorithms like SVD data has to be vectorized. Hence, compared to classical methods, higher redundancy reduction with less information loss can be achieved through decreasing present redundancies in all dimensions. In other words, HOSVD approximation results in a better compact data representation with respect to least square sense and geological consistency in comparison with classical algorithms. We examined the performance of the proposed parameterization technique against SVD approach on the SPE10 benchmark reservoir model as well as synthetic channelized permeability maps to demonstrate the capability of the proposed method. Moreover, to acquire statistical consistency, we repeat all experiments for a set of 1000 unknown geological samples and provide comparison using RMSE analysis. Results prove that, for a fixed compression ratio, the performance of the proposed approach
Higher order harmonic detection for exploring nonlinear interactions with nanoscale resolution.
Vasudevan, R K; Okatan, M Baris; Rajapaksa, I; Kim, Y; Marincel, D; Trolier-McKinstry, S; Jesse, S; Valanoor, N; Kalinin, S V
2013-01-01
Nonlinear dynamics underpin a vast array of physical phenomena ranging from interfacial motion to jamming transitions. In many cases, insight into the nonlinear behavior can be gleaned through exploration of higher order harmonics. Here, a method using band excitation scanning probe microscopy (SPM) to investigate higher order harmonics of the electromechanical response, with nanometer scale spatial resolution is presented. The technique is demonstrated by probing the first three harmonics of strain for a Pb(Zr(1-x)Ti(x))O₃ (PZT) ferroelectric capacitor. It is shown that the second order harmonic response is correlated with the first harmonic response, whereas the third harmonic is not. Additionally, measurements of the second harmonic reveal significant deviations from Rayleigh-type models in the form of a much more complicated field dependence than is observed in the spatially averaged data. These results illustrate the versatility of n(th) order harmonic SPM detection methods in exploring nonlinear phenomena in nanoscale materials.
Higher-order numerical methods derived from three-point polynomial interpolation
NASA Technical Reports Server (NTRS)
Rubin, S. G.; Khosla, P. K.
1976-01-01
Higher-order collocation procedures resulting in tridiagonal matrix systems are derived from polynomial spline interpolation and Hermitian finite-difference discretization. The equations generally apply for both uniform and variable meshes. Hybrid schemes resulting from different polynomial approximations for first and second derivatives lead to the nonuniform mesh extension of the so-called compact or Pade difference techniques. A variety of fourth-order methods are described and this concept is extended to sixth-order. Solutions with these procedures are presented for the similar and non-similar boundary layer equations with and without mass transfer, the Burgers equation, and the incompressible viscous flow in a driven cavity. Finally, the interpolation procedure is used to derive higher-order temporal integration schemes and results are shown for the diffusion equation.
NASA Astrophysics Data System (ADS)
Adnan Elshafei, M.; Alraiess, Fuzy
2013-03-01
In the current work, a finite element formulation is developed for modeling and analysis of isotropic as well as orthotropic composite beams with distributed piezoelectric actuators subjected to both mechanical and electrical loads. The proposed model is developed based on a simple higher order shear deformation theory where the displacement field equations in the model account for a parabolic distribution of the shear strain and the nonlinearity of in-plane displacements across the thickness and subsequently the shear correction factor is not involved. The virtual displacement method is used to formulate the equations of motion of the structure system. The model is valid for both segmented and continuous piezoelectric elements, which can be either surface bonded or embedded in the laminated beams. A two-node element with four mechanical degrees of freedom in addition to one electrical degree of freedom for each node is used in the finite element formulation. The electric potential is considered as a function of the thickness and the length of the beam element. A MATLAB code is developed to compute the static deformation and free vibration parameters of the beams with distributed piezoelectric actuators. The obtained results from the proposed model are compared with the available analytical results and the finite element results of other researchers.
Object representation for multi-beam sonar image using local higher-order statistics
NASA Astrophysics Data System (ADS)
Li, Haisen; Gao, Jue; Du, Weidong; Zhou, Tian; Xu, Chao; Chen, Baowei
2017-01-01
Multi-beam sonar imaging has been widely used in various underwater tasks such as object recognition and object tracking. Problems remain, however, when the sonar images are characterized by low signal-to-noise ratio, low resolution, and amplitude alterations due to viewpoint changes. This paper investigates the capacity of local higher-order statistics (HOS) to represent objects in multi-beam sonar images. The Weibull distribution has been used for modeling the background of the image. Local HOS involving skewness is estimated using a sliding computational window, thus generating the local skewness image of which a square structure is associated with a potential object. The ability of object representation with different signal-to-noise ratio (SNR) between object and background is analyzed, and the choice of the computational window size is discussed. In the case of the object with high SNR, a novel algorithm based on background estimation is proposed to reduce side lobe and retain object regions. The performance of object representation has been evaluated using real data that provided encouraging results in the case of the object with low amplitude, high side lobes, or large fluctuant amplitude. In conclusion, local HOS provides more reliable and stable information relating to the potential object and improves the object representation in multi-beam sonar image.
Externalizing behavior and the higher order factors of the Big Five.
Deyoung, Colin G; Peterson, Jordan B; Séguin, Jean R; Tremblay, Richard E
2008-11-01
The comorbidity of various externalizing behaviors stems from a broad predisposition that is strongly genetically determined (R. F. Krueger, B. M. Hicks, C. J. Patrick, S. R. Carlson, W. G. Iacono, & M. McGue, 2002). This finding raises the question of how externalizing behavior is related to broad personality traits that have been identified in normal populations and that also have a genetic component. Using structural equation modeling, the authors applied a hierarchical personality model based on the Big Five and their two higher order factors, Stability (Neuroticism reversed, Agreeableness, and Conscientiousness) and Plasticity (Extraversion and Openness). Cognitive ability was included to separate variance in Openness associated with Extraversion (hypothesized to be positively related to externalizing behavior) from variance in Openness associated with cognitive ability (negatively related to externalizing behavior). This model was used to predict a latent externalizing behavior variable in an adolescent male sample (N = 140) assessed through self- and teacher reports. As hypothesized, externalizing behavior was characterized by low Stability, high Plasticity, and low cognitive ability.
Triangular Alignment (TAME). A Tensor-based Approach for Higher-order Network Alignment
Mohammadi, Shahin; Gleich, David F.; Kolda, Tamara G.; Grama, Ananth
2015-11-01
Network alignment is an important tool with extensive applications in comparative interactomics. Traditional approaches aim to simultaneously maximize the number of conserved edges and the underlying similarity of aligned entities. We propose a novel formulation of the network alignment problem that extends topological similarity to higher-order structures and provide a new objective function that maximizes the number of aligned substructures. This objective function corresponds to an integer programming problem, which is NP-hard. Consequently, we approximate this objective function as a surrogate function whose maximization results in a tensor eigenvalue problem. Based on this formulation, we present an algorithm called Triangular AlignMEnt (TAME), which attempts to maximize the number of aligned triangles across networks. We focus on alignment of triangles because of their enrichment in complex networks; however, our formulation and resulting algorithms can be applied to general motifs. Using a case study on the NAPABench dataset, we show that TAME is capable of producing alignments with up to 99% accuracy in terms of aligned nodes. We further evaluate our method by aligning yeast and human interactomes. Our results indicate that TAME outperforms the state-of-art alignment methods both in terms of biological and topological quality of the alignments.
Grigoryev, S A; Bednar, J; Woodcock, C L
1999-02-26
Terminal cell differentiation is correlated with the extensive sequestering of previously active genes into compact transcriptionally inert heterochromatin. In vertebrate blood cells, these changes can be traced to the accumulation of a developmentally regulated heterochromatin protein, MENT. Cryoelectron microscopy of chicken granulocyte chromatin, which is highly enriched with MENT, reveals exceptionally compact polynucleosomes, which maintain a level of higher order folding above that imposed by linker histones. The amino acid sequence of MENT reveals a close structural relationship with serpins, a large family of proteins known for their ability to undergo dramatic conformational transitions. Conservation of the "hinge region" consensus in MENT indicates that this ability is retained by the protein. MENT is distinguished from the other serpins by being a basic protein, containing several positively charged surface clusters, which are likely to be involved in ionic interactions with DNA. One of the positively charged domains bears a significant similarity to the chromatin binding region of nuclear lamina proteins and with the A.T-rich DNA-binding motif, which may account for the targeting of MENT to peripheral heterochromatin. MENT ectopically expressed in a mammalian cell line is transported into nuclei and is associated with intranuclear foci of condensed chromatin.
Lax Pairs and Integrability Conditions of Higher-Order Nonlinear Schrödinger Equations
NASA Astrophysics Data System (ADS)
Asad-uz-zaman, M.; Chachou Samet, H.; Khawaja, U. Al
2016-08-01
We derive the Lax pairs and integrability conditions of the nonlinear Schrödinger equation with higher-order terms, complex potentials, and time-dependent coefficients. Cubic and quintic nonlinearities together with derivative terms are considered. The Lax pairs and integrability conditions for some of the well-known nonlinear Schrödinger equations, including a new equation which was not considered previously in the literature, are then derived as special cases. We show most clearly with a similarity transformation that the higher-order terms restrict the integrability to linear potential in contrast with quadratic potential for the standard nonlinear Schrödinger equation.
A higher-order split-step Fourier parabolic-equation sound propagation solution scheme.
Lin, Ying-Tsong; Duda, Timothy F
2012-08-01
A three-dimensional Cartesian parabolic-equation model with a higher-order approximation to the square-root Helmholtz operator is presented for simulating underwater sound propagation in ocean waveguides. The higher-order approximation includes cross terms with the free-space square-root Helmholtz operator and the medium phase speed anomaly. It can be implemented with a split-step Fourier algorithm to solve for sound pressure in the model. Two idealized ocean waveguide examples are presented to demonstrate the performance of this numerical technique.
NASA Astrophysics Data System (ADS)
Yuan, Zhen; Zhang, Qizhi; Sobel, Eric; Jiang, Huabei
2009-09-01
In this study, a simplified spherical harmonics approximated higher order diffusion model is employed for 3-D diffuse optical tomography of osteoarthritis in the finger joints. We find that the use of a higher-order diffusion model in a stand-alone framework provides significant improvement in reconstruction accuracy over the diffusion approximation model. However, we also find that this is not the case in the image-guided setting when spatial prior knowledge from x-rays is incorporated. The results show that the reconstruction error between these two models is about 15 and 4%, respectively, for stand-alone and image-guided frameworks.
Mixed Electromagnetic and Circuit Simulations using Higher-Order Elements and Bases
Champagne, N J; Rockway, J D; Jandhyala, V
2003-06-18
In this paper, an approach to couple higher-order electromagnetic surface integral equations to circuit simulations is presented. Terminals are defined that connect circuit elements to contacts modeled on the distributed electromagnetic domain. A modified charge-current continuity equation is proposed for a generalized KCL connection at the contacts. The distributive electromagnetic integral equations are developed using higher-order bases and elements that allow both better convergence and accuracy for modeling. The resulting scheme enables simultaneous solution of electromagnetic integral equations for arbitrarily-shaped objects and SPICE-like modeling for lumped circuits, and permits design iterations and visualization of the interaction between the two domains.
Hubbs-Tait, Laura; Page, Melanie C.; Huey, Erron L.; Starost, Huei-Juang; Culp, Anne McDonald; Culp, Rex E.; Harper, M. Elizabeth
2009-01-01
We proposed a higher order latent construct of parenting young children, parenting quality. This higher-order latent construct comprises five component constructs: demographic protection, psychological distress, psychosocial maturity, moral and cognitive reflectivity, and parenting attitudes and beliefs. We evaluated this model with data provided by 199 mothers of 4-year-old children enrolled in Head Start. The model was confirmed with only one adjustment suggested by modification indices. Final RMSEA was .05, CFI .96, and NNFI .94, indicating good model fit. Results were interpreted as emphasizing the interdependence of psychological and environmental demands on parenting. Implications of the model for teachers, early interventionists, and public policy are discussed. PMID:19629192
NASA Technical Reports Server (NTRS)
Majumdar, A. K.
1979-01-01
Expressions are derived for higher-order skewness and excess coefficients using central moments and cumulants up to 8th order. These coefficients are then calculated for three probability distributions: (1) Log-normal, (2) Rice-Nakagami, and (3) Gamma distributions. Curves are given to shown the variation of skewness with excess coefficients for these distributions. These curves are independent of the particular distribution parameters. This method is useful for studying fluctuating phenomena, which obey non-Gaussian statistics.
Lee, Jennifer E; Watson, David; Frey Law, Laura A
2010-01-01
Pain is a debilitating condition affecting millions each year, yet what predisposes certain individuals to be more sensitive to pain remains relatively unknown. Several psychological factors have been associated with pain perception, but the structural relations between multiple higher- and lower-order constructs and pain are not well understood. Thus, we aimed to examine the associations between pain perception using the cold pressor task (CPT), higher-order personality traits (neuroticism, negative affectivity, trait anxiety, extraversion, positive affectivity, psychoticism), and lower-order pain-related psychological constructs (pain catastrophizing [pre- and post], fear of pain, anxiety sensitivity, somatosensory amplification, hypochondriasis) in 66 pain-free adults. Factor analysis revealed three latent psychological variables: pain- or body-sensitivity, negative affect/neuroticism, and positive affect/extraversion. Similarly, pain responses factored into three domains: intensity, quality, and tolerance. Regression and correlation analyses demonstrated 1) all the lower-order pain constructs (fear, catastrophizing, and hypochondriasis) are related through a single underlying latent factor, that is partially related to the higher-order negative-valence personality traits; 2) pain- or body-sensitivity was more strongly predictive of pain quality than higher-order traits; and 3) the form of pain assessment is important – only qualitative pain ratings were significantly predicted by the psychological factors. Perspective: Consistent with the biopsychosocial model, these results suggest multiple pain-related psychological measures likely assess a common underlying factor, which is more predictive of qualitative than intensity pain ratings. This information may be useful for the development and advancement of pain assessments and treatments while considering the multidimensional nature of pain. PMID:20356801
Assessment of Higher-Order RANS Closures in a Decelerated Planar Wall-Bounded Turbulent Flow
NASA Technical Reports Server (NTRS)
Jeyapaul, Elbert; Coleman, Gary N.; Rumsey, Christopher L.
2014-01-01
A reference DNS database is presented, which includes third- and fourth-order moment budgets for unstrained and strained planar channel flow. Existing RANS closure models for third- and fourth-order terms are surveyed, and new model ideas are introduced. The various models are then compared with the DNS data term by term using a priori testing of the higher-order budgets of turbulence transport, velocity-pressure-gradient, and dissipation for both the unstrained and strained databases. Generally, the models for the velocity-pressure-gradient terms are most in need of improvement.
Constraints on tree-level higher order gravitational couplings in superstring theory.
Stieberger, Stephan
2011-03-18
We consider the scattering amplitudes of five and six gravitons at tree level in superstring theory. Their power series expansions in the Regge slope α' are analyzed through the order α'(8) showing some interesting constraints on higher order gravitational couplings in the effective superstring action such as the absence of R(5) terms. Furthermore, some transcendentality constraints on the coefficients of the nonvanishing couplings are observed: the absence of zeta values of even weight through the order α'(8) like the absence of ζ(2)ζ(3)R(6) terms. Our analysis is valid for any superstring background in any space-time dimension, which allows for a conformal field theory description.
Gibbons-Hawking boundary terms and junction conditions for higher-order brane gravity models
Balcerzak, Adam; Dabrowski, Mariusz P. E-mail: mpdabfz@wmf.univ.szczecin.pl
2009-01-15
We derive the most general junction conditions for the fourth-order brane gravity constructed of arbitrary functions of curvature invariants. We reduce these fourth-order theories to second order theories at the expense of introducing new scalar and tensor fields - the scalaron and the tensoron. In order to obtain junction conditions we apply the method of generalized Gibbons-Hawking boundary terms which are appended to the appropriate actions. After assuming the continuity of the scalaron and the tensoron on the brane, we recover junction conditions for such general brane universe models previously obtained by different methods. The derived junction conditions can serve studying the cosmological implications of the higher-order brane gravity models.
Nonlinear identification of the total baroreflex arc: higher-order nonlinearity.
Moslehpour, Mohsen; Kawada, Toru; Sunagawa, Kenji; Sugimachi, Masaru; Mukkamala, Ramakrishna
2016-12-01
The total baroreflex arc is the open-loop system relating carotid sinus pressure (CSP) to arterial pressure (AP). The nonlinear dynamics of this system were recently characterized. First, Gaussian white noise CSP stimulation was employed in open-loop conditions in normotensive and hypertensive rats with sectioned vagal and aortic depressor nerves. Nonparametric system identification was then applied to measured CSP and AP to establish a second-order nonlinear Uryson model. The aim in this study was to assess the importance of higher-order nonlinear dynamics via development and evaluation of a third-order nonlinear model of the total arc using the same experimental data. Third-order Volterra and Uryson models were developed by employing nonparametric and parametric identification methods. The R(2) values between the AP predicted by the best third-order Volterra model and measured AP in response to Gaussian white noise CSP not utilized in developing the model were 0.69 ± 0.03 and 0.70 ± 0.03 for normotensive and hypertensive rats, respectively. The analogous R(2) values for the best third-order Uryson model were 0.71 ± 0.03 and 0.73 ± 0.03. These R(2) values were not statistically different from the corresponding values for the previously established second-order Uryson model, which were both 0.71 ± 0.03 (P > 0.1). Furthermore, none of the third-order models predicted well-known nonlinear behaviors including thresholding and saturation better than the second-order Uryson model. Additional experiments suggested that the unexplained AP variance was partly due to higher brain center activity. In conclusion, the second-order Uryson model sufficed to represent the sympathetically mediated total arc under the employed experimental conditions.
A Study of Low Cloud Climate Feedbacks Using a Generalized Higher-Order Closure Subgrid Model
NASA Astrophysics Data System (ADS)
Firl, Grant J.
One of the biggest uncertainties in projections of future climate is whether and how low cloudiness will change and whether that change will feed back on the climate system. Much of the uncertainty revolves around the difference in scales between the processes that govern low cloudiness and the processes that can be resolved in climate models, a fact that relegates shallow convection to the parameterization realm with varying levels of success. A new subgrid-scale parameterization, named THOR, has been developed in an effort to improve the representation of low cloudiness via parameterization in climate models. THOR uses the higher-order closure approach to determine the statistics describing subgrid-scale processes. These statistics are used to determine a trivariate double-Gaussian PDF among vertical velocity, ice-liquid water potential temperature, and total water specific humidity. With this information, one can diagnose what portion of the grid cell is cloudy, subgrid-scale cloud water content, and subgrid-scale vertical cloud water flux. In addition, samples are drawn from the trivariate PDF in order to drive the microphysics and radiation schemes. Although schemes similar to THOR have been developed over the past decade, THOR includes several novel concepts, like the generalization of the saturation curve to include condensation over both ice and liquid substrates, the determination of the PDF parameters from the given turbulence statistics, the introduction of a stochastic parcel entrainment process for the turbulence length scale, and a sub-column approach for calculating radiative transfer using the PDF. The new model is validated by simulating five test cases spanning a wide range of boundary layer cloud types, from stratocumulus to cumulus and the transition between the two. The results are compared to an ensemble of LES models running the same cases, with particular attention paid to turbulence statistics and cloud structure. For all cloud types tested
Higher Order Testlet Response Models for Hierarchical Latent Traits and Testlet-Based Items
ERIC Educational Resources Information Center
Huang, Hung-Yu; Wang, Wen-Chung
2013-01-01
Both testlet design and hierarchical latent traits are fairly common in educational and psychological measurements. This study aimed to develop a new class of higher order testlet response models that consider both local item dependence within testlets and a hierarchy of latent traits. Due to high dimensionality, the authors adopted the Bayesian…
Second- and Higher-Order Virial Coefficients Derived from Equations of State for Real Gases
ERIC Educational Resources Information Center
Parkinson, William A.
2009-01-01
Derivation of the second- and higher-order virial coefficients for models of the gaseous state is demonstrated by employing a direct differential method and subsequent term-by-term comparison to power series expansions. This communication demonstrates the application of this technique to van der Waals representations of virial coefficients.…
Using Higher Order Thinking Questions to Foster Critical Thinking: A Classroom Study
ERIC Educational Resources Information Center
Barnett, Jerrold E.; Francis, Alisha L.
2012-01-01
To determine if quizzes containing higher order thinking questions are related to critical thinking and test performance when utilised in conjunction with an immersion approach to instruction and effort-based grading, sections of an "Educational Psychology" course were assigned to one of three quizzing conditions. Quizzes contained…
Dichotomous Identification Keys: A Ladder to Higher Order Knowledge about the Human Body
ERIC Educational Resources Information Center
Sorgo, Andrej
2006-01-01
We tried to enrich teaching human anatomy in high school biology lessons. Students construct dichotomous identification keys to the cells, tissues, organs, or body parts. By doing this, students have achieved higher-order cognitive levels of knowledge because construction of such keys is based on analysis, synthesis, and evaluation. Students found…
Nonstandard and Higher-Order Finite-Difference Methods for Electromagnetics
2009-10-26
NONSTANDARD AND HIGHER-ORDER FINITE-DIFFERENCE METHODS FOR ELECTROMAGNETICS by Constantine A. Balanis Bo Yang Craig R. Birtcher Department of Electrical ...116 3.55. Geometry of the simulated free-space region. . . . . . . . . . . . . . . . . . 121 3.56. Normalized electric charge densities using... electric charge densities using the nonstandard differentiation of (3.78) and (3.87
Effect of Jigsaw II on Literal and Higher Order EFL Reading Comprehension
ERIC Educational Resources Information Center
Ghaith, Ghazi; El-Malak, Mirna Abd
2004-01-01
The present study examines the effect of the cooperative Jigsaw II method on improving literal and higher order reading comprehension in English as a foreign language (EFL). Forty-eight ( n = 48) students of EFL participated in the study and a pretest-posttest control group experimental design was employed. The results indicated no statistically…
The grounding of higher order concepts in action and language: a cognitive robotics model.
Stramandinoli, Francesca; Marocco, Davide; Cangelosi, Angelo
2012-08-01
In this paper we present a neuro-robotic model that uses artificial neural networks for investigating the relations between the development of symbol manipulation capabilities and of sensorimotor knowledge in the humanoid robot iCub. We describe a cognitive robotics model in which the linguistic input provided by the experimenter guides the autonomous organization of the robot's knowledge. In this model, sequences of linguistic inputs lead to the development of higher-order concepts grounded on basic concepts and actions. In particular, we show that higher-order symbolic representations can be indirectly grounded in action primitives directly grounded in sensorimotor experiences. The use of recurrent neural network also permits the learning of higher-order concepts based on temporal sequences of action primitives. Hence, the meaning of a higher-order concept is obtained through the combination of basic sensorimotor knowledge. We argue that such a hierarchical organization of concepts can be a possible account for the acquisition of abstract words in cognitive robots.
ERIC Educational Resources Information Center
Kidwai, Khusro; Munyofu, Mine; Swain, William J; Ausman, Bradley D.; Lin, Huifen; Dwyer, Francis
2001-01-01
Animation is being used extensively for instructional purposes; however, it has not been found to be effective on measures of higher order learning (concepts, rules, procedures) within the knowledge acquisition and knowledge integration domains. The purpose of this study was to examine the instructional effectiveness of two visual scaffolding…
Oscillation of certain higher-order neutral partial functional differential equations.
Li, Wei Nian; Sheng, Weihong
2016-01-01
In this paper, we study the oscillation of certain higher-order neutral partial functional differential equations with the Robin boundary conditions. Some oscillation criteria are established. Two examples are given to illustrate the main results in the end of this paper.
Purposely Teaching for the Promotion of Higher-Order Thinking Skills: A Case of Critical Thinking
ERIC Educational Resources Information Center
Miri, Barak; Ben-Chaim, David; Zoller, Uri
2007-01-01
This longitudinal case-study aimed at examining whether purposely teaching for the promotion of higher order thinking skills enhances students' critical thinking (CT), within the framework of science education. Within a pre-, post-, and post-post experimental design, high school students, were divided into three research groups. The experimental…
Media Literacy, Popular Culture, and the Transfer of Higher Order Thinking Abilities.
ERIC Educational Resources Information Center
Mraz, Maryann; Heron, Alison H.; Wood, Karen
2003-01-01
Contends that by acknowledging the influence of media literacy on adolescents' lives outside the classroom, teachers have a potential source for motivating student interest and eliciting their higher order thinking abilities within the classroom. Specifically addresses merging popular culture with classroom culture and provides a paradigm for…
ERIC Educational Resources Information Center
Brady, Timothy F.; Tenenbaum, Joshua B.
2013-01-01
When remembering a real-world scene, people encode both detailed information about specific objects and higher order information like the overall gist of the scene. However, formal models of change detection, like those used to estimate visual working memory capacity, assume observers encode only a simple memory representation that includes no…
Radiation characteristics and generation of higher-order modes of circular microstrip antennas
NASA Astrophysics Data System (ADS)
Kumar, G.; Shafai, L.
1984-08-01
The characteristics of higher-order modes of circular microstrip antennas, such as radiation pattern, directivity, bandwidth, efficiency, and location of the feedpoint to match a 50 ohm line, are studied, and the effects of varying the substrate parameters are investigated. A multifeed technique to generate any particular mode is also presented.
Conception of Teaching Higher Order Thinking: Perspectives of Chinese Teachers in Hong Kong
ERIC Educational Resources Information Center
Yeung, Sze-yin Shirley
2015-01-01
Enhancing the higher order thinking (HOT) ability of students is a worldwide educational goal. This has also become a significant objective in the curriculum reforms in Hong Kong, which aims at better preparation of students to meet the challenges of the new era. Cultural aspects are often regarded as salient in determining approaches to teaching.…
Higher-Order Thinking Development through Adaptive Problem-Based Learning
ERIC Educational Resources Information Center
Raiyn, Jamal; Tilchin, Oleg
2015-01-01
In this paper we propose an approach to organizing Adaptive Problem-Based Learning (PBL) leading to the development of Higher-Order Thinking (HOT) skills and collaborative skills in students. Adaptability of PBL is expressed by changes in fixed instructor assessments caused by the dynamics of developing HOT skills needed for problem solving,…
ERIC Educational Resources Information Center
Tanujaya, Benidiktus
2016-01-01
The purpose of this research was to develop an instrument that can be used to measure higher-order thinking skills (HOTS) in mathematics instruction of high school students. This research was conducted using a standard procedure of instrument development, from the development of conceptual definitions, development of operational definitions,…
Improving Higher Order Thinking Skills among Freshmen by Teaching Science through Inquiry
ERIC Educational Resources Information Center
Hugerat, Muhamad; Kortam, Naji
2014-01-01
Twenty-eight freshmen majoring in biology and/or chemistry in an Arab college in Israel, were given a pre-test and a post-test in which they had to identify the control group and design a controlled experiment. During the course an intervention was used. Science was taught by inquiry while using strategies that promote higher-order thinking skills…
ESL Students' Perceptions of the Use of Higher Order Thinking Skills in English Language Writing
ERIC Educational Resources Information Center
Ganapathy, Malini; Kaur, Sarjit
2014-01-01
The transformation of the education curriculum in the Malaysia Education Development Plan (PPPM) 2013-2025 focuses on the Higher Order Thinking (HOT) concept which aims to produce knowledgeable students who are critical and creative in their thinking and can compete at the international level. HOT skills encourage students to apply, analyse,…
ERIC Educational Resources Information Center
Solomon, Sheila
This practicum study evaluated a non-basal, multidisciplinary, multisensory approach to teaching higher order reading comprehension skills to eight fifth-grade learning-disabled students from low socioeconomic minority group backgrounds. The four comprehension skills were: (1) identifying the main idea; (2) determining cause and effect; (3) making…
Sleep inertia, sleep homeostatic, and circadian influences on higher-order cognitive functions
Ronda, Joseph M.; Czeisler, Charles A.; Wright, Kenneth P.
2016-01-01
Summary Sleep inertia, sleep homeostatic, and circadian processes modulate cognition, including reaction time, memory, mood, and alertness. How these processes influence higher-order cognitive functions is not well known. Six participants completed a 73-daylong study that included two 14-daylong 28h forced desynchrony protocols, to examine separate and interacting influences of sleep inertia, sleep homeostasis, and circadian phase on higher-order cognitive functions of inhibitory control and selective visual attention. Cognitive performance for most measures was impaired immediately after scheduled awakening and improved over the first ~2-4h of wakefulness (sleep inertia); worsened thereafter until scheduled bedtime (sleep homeostasis); and was worst at ~60° and best at ~240° (circadian modulation, with worst and best phases corresponding to ~9AM and ~9PM respectively, in individuals with a habitual waketime of 7AM). The relative influences of sleep inertia, sleep homeostasis, and circadian phase depended on the specific higher-order cognitive function task examined. Inhibitory control appeared to be modulated most strongly by circadian phase, whereas selective visual attention for a spatial-configuration search task was modulated most strongly by sleep inertia. These findings demonstrate that some higher-order cognitive processes are differentially sensitive to different sleep-wake regulatory processes. Differential modulation of cognitive functions by different sleep-wake regulatory processes has important implications for understanding mechanisms contributing to performance impairments during adverse circadian phases, sleep deprivation, and/or upon awakening from sleep. PMID:25773686
How to Assess Higher-Order Thinking Skills in Your Classroom
ERIC Educational Resources Information Center
Brookhart, Susan M.
2010-01-01
Don't settle for assessing recall and comprehension only when you can use this guide to create assessments for higher-order thinking skills. Assessment expert Susan M. Brookhart brings you up to speed on how to develop and use test questions and other assessments that reveal how well your students can analyze, reason, solve problems, and think…
Higher-Order Fertility among Urban Fathers: An Overlooked Issue for a Neglected Population
ERIC Educational Resources Information Center
Bronte-Tinkew, Jacinta; Ryan, Suzanne; Franzetta, Kerry; Manlove, Jennifer; Lilja, Emily
2009-01-01
The study includes a longitudinal sample of 1,989 fathers from the Fragile Families and Child Wellbeing study and examines factors associated with fathering a higher-order birth (three or more children) and compares these factors to those predicting any subsequent birth. Also, the article examines differences by marital status. Logistic regression…
ERIC Educational Resources Information Center
Shen, Yan; Hannafin, Michael
2013-01-01
This study is part of an ongoing design research to scaffold preservice teachers' higher-order reasoning while solving technology integration problems. Informed by previous iterations, we designed and examined progressively increasing scaffolds that integrated multiple scaffolding functions to facilitate three technology-based lesson design…
Developing Higher-Order Thinking Skills through the Use of Technology.
ERIC Educational Resources Information Center
Coleman, Connie; King, Jeff; Ruth, Mary Helen; Stary, Erin
This report describes a program, utilizing both critical and creative thinking skills, to enhance the educational process through the use of technology. The targeted population consisted of fourth grade students in a growing middle class community located in northern Illinois. The lack of higher-order thinking skills was documented through…
ERIC Educational Resources Information Center
Dori, Yehudit J.; Tal, Revital T.; Tsaushu, Masha
2003-01-01
Teaching nonscience majors topics in biotechnology through case studies is the focus of this research. Our "Biotechnology, Environment, and Related Issues" module, developed within the "Science for All" framework, is aimed at elevating the level of students' scientific and technological literacy and their higher order thinking…
NASA Astrophysics Data System (ADS)
Geng, Weihua
2013-05-01
In this paper, we present a parallel higher-order boundary integral method to solve the linear Poisson-Boltzmann (PB) equation. In our method, a well-posed boundary integral formulation is used to ensure the fast convergence of Krylov subspace linear solver such as GMRES. The molecular surfaces are first discretized with flat triangles and then converted to curved triangles with the assistance of normal information at vertices. To maintain the desired accuracy, four-point Gauss-Radau quadratures are used on regular triangles and sixteen-point Gauss-Legendre quadratures together with regularization transformations are applied on singular triangles. To speed up our method, we take advantage of the embarrassingly parallel feature of boundary integral formulation, and parallelize the schemes with the message passing interface (MPI) implementation. Numerical tests show significantly improved accuracy and convergence of the proposed higher-order boundary integral Poisson-Boltzmann (HOBI-PB) solver compared with boundary integral PB solver using often-seen centroid collocation on flat triangles. The higher-order accuracy results achieved by present method are important to sensitive solvation analysis of biomolecules, particularly when accurate electrostatic surface potentials are critical in the molecular simulation. In addition, the higher-order boundary integral schemes presented here and their associated parallelization potentially can be applied to solving boundary integral equations in a general sense.
Integrability Test and Travelling-Wave Solutions of Higher-Order Shallow- Water Type Equations
NASA Astrophysics Data System (ADS)
Maldonado, Mercedes; Molinero, María Celeste; Pickering, Andrew; Prada, Julia
2010-04-01
We apply the Weiss-Tabor-Carnevale (WTC) Painlevé test to members of a sequence of higher-order shallow-water type equations. We obtain the result that the equations considered are non-integrable, although compatibility conditions at real resonances are satisfied. We also construct travelling-wave solutions for these and related equations.
Geometric Hamilton-Jacobi theory for higher-order autonomous systems
NASA Astrophysics Data System (ADS)
Colombo, Leonardo; de León, Manuel; Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso
2014-06-01
The geometric framework for the Hamilton-Jacobi theory is used to study this theory in the background of higher-order mechanical systems, in both the Lagrangian and Hamiltonian formalisms. Thus, we state the corresponding Hamilton-Jacobi equations in these formalisms and apply our results to analyze some particular physical examples.