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 Genome Organization in Human Disease
Misteli, Tom
2010-01-01
Genomes are organized into complex higher-order structures by folding of the DNA into chromatin fibers, chromosome domains, and ultimately chromosomes. The higher-order organization of genomes is functionally important for gene regulation and control of gene expression programs. Defects in how chromatin is globally organized are relevant for physiological and pathological processes. Mutations and transcriptional misregulation of several global genome organizers are linked to human diseases and global alterations in chromatin structure are emerging as key players in maintenance of genome stability, aging, and the formation of cancer translocations. PMID:20591991
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…
Higher-order Multivariable Polynomial Regression to Estimate Human Affective States
NASA Astrophysics Data System (ADS)
Wei, Jie; Chen, Tong; Liu, Guangyuan; Yang, Jiemin
2016-03-01
From direct observations, facial, vocal, gestural, physiological, and central nervous signals, estimating human affective states through computational models such as multivariate linear-regression analysis, support vector regression, and artificial neural network, have been proposed in the past decade. In these models, linear models are generally lack of precision because of ignoring intrinsic nonlinearities of complex psychophysiological processes; and nonlinear models commonly adopt complicated algorithms. To improve accuracy and simplify model, we introduce a new computational modeling method named as higher-order multivariable polynomial regression to estimate human affective states. The study employs standardized pictures in the International Affective Picture System to induce thirty subjects’ affective states, and obtains pure affective patterns of skin conductance as input variables to the higher-order multivariable polynomial model for predicting affective valence and arousal. Experimental results show that our method is able to obtain efficient correlation coefficients of 0.98 and 0.96 for estimation of affective valence and arousal, respectively. Moreover, the method may provide certain indirect evidences that valence and arousal have their brain’s motivational circuit origins. Thus, the proposed method can serve as a novel one for efficiently estimating human affective states.
Higher-order Multivariable Polynomial Regression to Estimate Human Affective States.
Wei, Jie; Chen, Tong; Liu, Guangyuan; Yang, Jiemin
2016-01-01
From direct observations, facial, vocal, gestural, physiological, and central nervous signals, estimating human affective states through computational models such as multivariate linear-regression analysis, support vector regression, and artificial neural network, have been proposed in the past decade. In these models, linear models are generally lack of precision because of ignoring intrinsic nonlinearities of complex psychophysiological processes; and nonlinear models commonly adopt complicated algorithms. To improve accuracy and simplify model, we introduce a new computational modeling method named as higher-order multivariable polynomial regression to estimate human affective states. The study employs standardized pictures in the International Affective Picture System to induce thirty subjects' affective states, and obtains pure affective patterns of skin conductance as input variables to the higher-order multivariable polynomial model for predicting affective valence and arousal. Experimental results show that our method is able to obtain efficient correlation coefficients of 0.98 and 0.96 for estimation of affective valence and arousal, respectively. Moreover, the method may provide certain indirect evidences that valence and arousal have their brain's motivational circuit origins. Thus, the proposed method can serve as a novel one for efficiently estimating human affective states. PMID:26996254
Higher-order Multivariable Polynomial Regression to Estimate Human Affective States
Wei, Jie; Chen, Tong; Liu, Guangyuan; Yang, Jiemin
2016-01-01
From direct observations, facial, vocal, gestural, physiological, and central nervous signals, estimating human affective states through computational models such as multivariate linear-regression analysis, support vector regression, and artificial neural network, have been proposed in the past decade. In these models, linear models are generally lack of precision because of ignoring intrinsic nonlinearities of complex psychophysiological processes; and nonlinear models commonly adopt complicated algorithms. To improve accuracy and simplify model, we introduce a new computational modeling method named as higher-order multivariable polynomial regression to estimate human affective states. The study employs standardized pictures in the International Affective Picture System to induce thirty subjects’ affective states, and obtains pure affective patterns of skin conductance as input variables to the higher-order multivariable polynomial model for predicting affective valence and arousal. Experimental results show that our method is able to obtain efficient correlation coefficients of 0.98 and 0.96 for estimation of affective valence and arousal, respectively. Moreover, the method may provide certain indirect evidences that valence and arousal have their brain’s motivational circuit origins. Thus, the proposed method can serve as a novel one for efficiently estimating human affective states. PMID:26996254
Measuring higher order optical aberrations of the human eye: techniques and applications.
Carvalho, L Alberto V; Castro, J C; Carvalho, L Antonio V
2002-11-01
In the present paper we discuss the development of "wave-front", an instrument for determining the lower and higher optical aberrations of the human eye. We also discuss the advantages that such instrumentation and techniques might bring to the ophthalmology professional of the 21st century. By shining a small light spot on the retina of subjects and observing the light that is reflected back from within the eye, we are able to quantitatively determine the amount of lower order aberrations (astigmatism, myopia, hyperopia) and higher order aberrations (coma, spherical aberration, etc.). We have measured artificial eyes with calibrated ametropia ranging from +5 to -5 D, with and without 2 D astigmatism with axis at 45 degrees and 90 degrees. We used a device known as the Hartmann-Shack (HS) sensor, originally developed for measuring the optical aberrations of optical instruments and general refracting surfaces in astronomical telescopes. The HS sensor sends information to a computer software for decomposition of wave-front aberrations into a set of Zernike polynomials. These polynomials have special mathematical properties and are more suitable in this case than the traditional Seidel polynomials. We have demonstrated that this technique is more precise than conventional autorefraction, with a root mean square error (RMSE) of less than 0.1 micro m for a 4-mm diameter pupil. In terms of dioptric power this represents an RMSE error of less than 0.04 D and 5 degrees for the axis. This precision is sufficient for customized corneal ablations, among other applications. PMID:12426641
NASA Astrophysics Data System (ADS)
Xue, Lixia; Dai, Yun; Rao, Xuejun; Wang, Cheng; Hu, Yiyun; Liu, Qian; Jiang, Wenhan
2008-01-01
Higher-order aberrations correction can improve visual performance of human eye to some extent. To evaluate how much visual benefit can be obtained with higher-order aberrations correction we developed an adaptive optics vision simulator (AOVS). Dynamic real time optimized modal compensation was used to implement various customized higher-order ocular aberrations correction strategies. The experimental results indicate that higher-order aberrations correction can improve visual performance of human eye comparing with only lower-order aberration correction but the improvement degree and higher-order aberration correction strategy are different from each individual. Some subjects can acquire great visual benefit when higher-order aberrations were corrected but some subjects acquire little visual benefit even though all higher-order aberrations were corrected. Therefore, relative to general lower-order aberrations correction strategy, customized higher-order aberrations correction strategy is needed to obtain optimal visual improvement for each individual. AOVS provides an effective tool for higher-order ocular aberrations optometry for customized ocular aberrations correction.
Modulation of Higher-Order Olfaction Components on Executive Functions in Humans
Fagundo, Ana B.; Jiménez-Murcia, Susana; Giner-Bartolomé, Cristina; Islam, Mohammed Anisul; de la Torre, Rafael; Pastor, Antoni; Casanueva, Felipe F.; Crujeiras, Ana B.; Granero, Roser; Baños, Rosa; Botella, Cristina; Fernández-Real, Jose M.; Frühbeck, Gema; Gómez-Ambrosi, Javier; Menchón, José M.; Tinahones, Francisco J.; Fernández-Aranda, Fernando
2015-01-01
The prefrontal (PFC) and orbitofrontal cortex (OFC) appear to be associated with both executive functions and olfaction. However, there is little data relating olfactory processing and executive functions in humans. The present study aimed at exploring the role of olfaction on executive functioning, making a distinction between primary and more cognitive aspects of olfaction. Three executive tasks of similar difficulty were used. One was used to assess hot executive functions (Iowa Gambling Task-IGT), and two as a measure of cold executive functioning (Stroop Colour and Word Test-SCWT and Wisconsin Card Sorting Test-WCST). Sixty two healthy participants were included: 31 with normosmia and 31 with hyposmia. Olfactory abilities were assessed using the ‘‘Sniffin’ Sticks’’ test and the olfactory threshold, odour discrimination and odour identification measures were obtained. All participants were female, aged between 18 and 60. Results showed that participants with hyposmia displayed worse performance in decision making (IGT; Cohen’s-d = 0.91) and cognitive flexibility (WCST; Cohen’s-d between 0.54 and 0.68) compared to those with normosmia. Multiple regression adjusted by the covariates participants’ age and education level showed a positive association between odour identification and the cognitive inhibition response (SCWT-interference; Beta = 0.29; p = .034). The odour discrimination capacity was not a predictor of the cognitive executive performance. Our results suggest that both hot and cold executive functions seem to be associated with higher-order olfactory functioning in humans. These results robustly support the hypothesis that olfaction and executive measures have a common neural substrate in PFC and OFC, and suggest that olfaction might be a reliable cognitive marker in psychiatric and neurologic disorders. PMID:26083418
Assessing reliable human mobility patterns from higher order memory in mobile communications.
Matamalas, Joan T; De Domenico, Manlio; Arenas, Alex
2016-08-01
Understanding how people move within a geographical area, e.g. a city, a country or the whole world, is fundamental in several applications, from predicting the spatio-temporal evolution of an epidemic to inferring migration patterns. Mobile phone records provide an excellent proxy of human mobility, showing that movements exhibit a high level of memory. However, the precise role of memory in widely adopted proxies of mobility, as mobile phone records, is unknown. Here we use 560 million call detail records from Senegal to show that standard Markovian approaches, including higher order ones, fail in capturing real mobility patterns and introduce spurious movements never observed in reality. We introduce an adaptive memory-driven approach to overcome such issues. At variance with Markovian models, it is able to realistically model conditional waiting times, i.e. the probability to stay in a specific area depending on individuals' historical movements. Our results demonstrate that in standard mobility models the individuals tend to diffuse faster than observed in reality, whereas the predictions of the adaptive memory approach significantly agree with observations. We show that, as a consequence, the incidence and the geographical spread of a disease could be inadequately estimated when standard approaches are used, with crucial implications on resources deployment and policy-making during an epidemic outbreak. PMID:27581479
Toda, Shinji; Fujita, Takeshi; Arakawa, Hirohisa; Toda, Kohji
2005-03-01
An ultrasonic nondestructive evaluation technique of the layer thickness in human teeth is proposed using a leaky Lamb wave device with two arch-shaped interdigital transducers, operating at a plate/water interface. The use of a higher-order-mode leaky Lamb wave with a phase velocity higher than the longitudinal wave velocity in the human tooth is essential to detect reflected ultrasound beams from the tooth section The layer thickness of dentin, estimated from the measured time interval between two reflected echoes, is in good agreement with the optically measured data.
Deletion of DXZ4 on the human inactive X chromosome alters higher-order genome architecture
Darrow, Emily M.; Huntley, Miriam H.; Dudchenko, Olga; Stamenova, Elena K.; Durand, Neva C.; Sun, Zhuo; Huang, Su-Chen; Sanborn, Adrian L.; Machol, Ido; Shamim, Muhammad; Seberg, Andrew P.; Lander, Eric S.; Chadwick, Brian P.; Aiden, Erez Lieberman
2016-01-01
During interphase, the inactive X chromosome (Xi) is largely transcriptionally silent and adopts an unusual 3D configuration known as the “Barr body.” Despite the importance of X chromosome inactivation, little is known about this 3D conformation. We recently showed that in humans the Xi chromosome exhibits three structural features, two of which are not shared by other chromosomes. First, like the chromosomes of many species, Xi forms compartments. Second, Xi is partitioned into two huge intervals, called “superdomains,” such that pairs of loci in the same superdomain tend to colocalize. The boundary between the superdomains lies near DXZ4, a macrosatellite repeat whose Xi allele extensively binds the protein CCCTC-binding factor. Third, Xi exhibits extremely large loops, up to 77 megabases long, called “superloops.” DXZ4 lies at the anchor of several superloops. Here, we combine 3D mapping, microscopy, and genome editing to study the structure of Xi, focusing on the role of DXZ4. We show that superloops and superdomains are conserved across eutherian mammals. By analyzing ligation events involving three or more loci, we demonstrate that DXZ4 and other superloop anchors tend to colocate simultaneously. Finally, we show that deleting DXZ4 on Xi leads to the disappearance of superdomains and superloops, changes in compartmentalization patterns, and changes in the distribution of chromatin marks. Thus, DXZ4 is essential for proper Xi packaging. PMID:27432957
Deletion of DXZ4 on the human inactive X chromosome alters higher-order genome architecture.
Darrow, Emily M; Huntley, Miriam H; Dudchenko, Olga; Stamenova, Elena K; Durand, Neva C; Sun, Zhuo; Huang, Su-Chen; Sanborn, Adrian L; Machol, Ido; Shamim, Muhammad; Seberg, Andrew P; Lander, Eric S; Chadwick, Brian P; Aiden, Erez Lieberman
2016-08-01
During interphase, the inactive X chromosome (Xi) is largely transcriptionally silent and adopts an unusual 3D configuration known as the "Barr body." Despite the importance of X chromosome inactivation, little is known about this 3D conformation. We recently showed that in humans the Xi chromosome exhibits three structural features, two of which are not shared by other chromosomes. First, like the chromosomes of many species, Xi forms compartments. Second, Xi is partitioned into two huge intervals, called "superdomains," such that pairs of loci in the same superdomain tend to colocalize. The boundary between the superdomains lies near DXZ4, a macrosatellite repeat whose Xi allele extensively binds the protein CCCTC-binding factor. Third, Xi exhibits extremely large loops, up to 77 megabases long, called "superloops." DXZ4 lies at the anchor of several superloops. Here, we combine 3D mapping, microscopy, and genome editing to study the structure of Xi, focusing on the role of DXZ4 We show that superloops and superdomains are conserved across eutherian mammals. By analyzing ligation events involving three or more loci, we demonstrate that DXZ4 and other superloop anchors tend to colocate simultaneously. Finally, we show that deleting DXZ4 on Xi leads to the disappearance of superdomains and superloops, changes in compartmentalization patterns, and changes in the distribution of chromatin marks. Thus, DXZ4 is essential for proper Xi packaging. PMID:27432957
Higher order stationary subspace analysis
NASA Astrophysics Data System (ADS)
Panknin, Danny; von Bünau, Paul; Kawanabe, Motoaki; Meinecke, Frank C.; Müller, Klaus-Robert
2016-03-01
Non-stationarity in data is an ubiquitous problem in signal processing. The recent stationary subspace analysis procedure (SSA) has enabled to decompose such data into a stationary subspace and a non-stationary part respectively. Algorithmically only weak non- stationarities could be tackled by SSA. The present paper takes the conceptual step generalizing from the use of first and second moments as in SSA to higher order moments, thus defining the proposed higher order stationary subspace analysis procedure (HOSSA). The paper derives the novel procedure and shows simulations. An obvious trade-off between the necessity of estimating higher moments and the accuracy and robustness with which they can be estimated is observed. In an ideal setting of plenty of data where higher moment information is dominating our novel approach can win against standard SSA. However, with limited data, even though higher moments actually dominate the underlying data, still SSA may arrive on par.
Hirosue, Akiyuki; Ishihara, Ko; Tokunaga, Kazuaki; Watanabe, Takehisa; Saitoh, Noriko; Nakamoto, Masafumi; Chandra, Tamir; Narita, Masashi; Shinohara, Masanori; Nakao, Mitsuyoshi
2012-06-01
Somatic cells can be reset to oncogene-induced senescent (OIS) cells or induced pluripotent stem (iPS) cells by expressing specified factors. The INK4/ARF locus encodes p15(INK4b) , ARF, and p16(INK4a) genes in human chromosome 9p21, the products of which are known as common key reprogramming regulators. Compared with growing fibroblasts, the CCCTC-binding factor CTCF is remarkably up-regulated in iPS cells with silencing of the three genes in the locus and is reversely down-regulated in OIS cells with high expression of p15(INK4b) and p16(INK4a) genes. There are at least three CTCF-enriched sites in the INK4/ARF locus, which possess chromatin loop-forming activities. These CTCF-enriched sites and the p16(INK4a) promoter associate to form compact chromatin loops in growing fibroblasts, while CTCF depletion disrupts the loop structure. Interestingly, the loose chromatin structure is found in OIS cells. In addition, the INK4/ARF locus has an intermediate type of chromatin compaction in iPS cells. These results suggest that senescent cells have distinct higher-order chromatin signature in the INK4/ARF locus. PMID:22340434
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.
Higher order architecture of collections of objects
NASA Astrophysics Data System (ADS)
Baas, Nils A.
2015-01-01
We show that on an arbitrary collection of objects there is a wide variety of higher order architectures governed by hyperstructures. Higher order gluing, local to global processes, fusion of collections, bridges and higher order types are discussed. We think that these types of architectures may have interesting applications in many areas of science.
Generalized structure of higher order nonclassicality
NASA Astrophysics Data System (ADS)
Verma, Amit; Pathak, Anirban
2010-02-01
A generalized notion of higher order nonclassicality (in terms of higher order moments) is introduced. Under this generalized framework of higher order nonclassicality, conditions of higher order squeezing and higher order subpoissonian photon statistics are derived. A simpler form of the Hong-Mandel higher order squeezing criterion is derived under this framework by using an operator ordering theorem introduced by us in [A. Pathak, J. Phys. A 33 (2000) 5607]. It is also generalized for multi-photon Bose operators of Brandt and Greenberg. Similarly, condition for higher order subpoissonian photon statistics is derived by normal ordering of higher powers of number operator. Further, with the help of simple density matrices, it is shown that the higher order antibunching (HOA) and higher order subpoissonian photon statistics (HOSPS) are not the manifestation of the same phenomenon and consequently it is incorrect to use the condition of HOA as a test of HOSPS. It is also shown that the HOA and HOSPS may exist even in absence of the corresponding lower order phenomenon. Binomial state, nonlinear first order excited squeezed state (NLESS) and nonlinear vacuum squeezed state (NLVSS) are used as examples of quantum state and it is shown that these states may show higher order nonclassical characteristics. It is observed that the Binomial state which is always antibunched, is not always higher order squeezed and NLVSS which shows higher order squeezing does not show HOSPS and HOA. The opposite is observed in NLESS and consequently it is established that the HOSPS and HOS are two independent signatures of higher order nonclassicality.
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 organization of complex networks.
Benson, Austin R; Gleich, David F; Leskovec, Jure
2016-07-01
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
Resonant radiation from oscillating higher order solitons.
Driben, R; Yulin, A V; Efimov, A
2015-07-27
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. It is shown that for longer pulses the described effect persists also under the action of higher order perturbations such as Raman and self-steepening. PMID:26367574
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.
Higher order differential-integral microphone arrays.
Abhayapala, Thushara D; Gupta, Aastha
2010-05-01
This paper develops theory to design higher order directional microphone arrays. The proposed higher order designs have similar inter sensor spacings as traditional first and second order differential arrays. The Jacobi-Anger expansion is used to exploit the underlying structure of microphone signals from pairs of closely spaced sensors. Specifically, the difference and sum of these microphone signals are processed to design the novel directional array. PMID:21117719
Higher order Godunov schemes for isothermal hydrodynamics
NASA Technical Reports Server (NTRS)
Balsara, Dinshaw S.
1994-01-01
In this paper we construct higher order Godunov schemes for isothermal flow. Isothermal hydrodynamics serves as a good representation for several systems of astrophysical interest. The schemes designed here have second-order accuracy in space and time and some are third-order accurate for advection. Moreover, several ingredients of these schemes are essential components of even higher order. The methods designed here have excellent ability to represent smooth flow yet capture shocks with high resolution. Several test problems are presented. The algorithms presented here are compared with other algorithms having a comparable formal order of accuracy.
Using Reflection to Develop Higher Order Processes
ERIC Educational Resources Information Center
Lerch, Carol; Bilics, Andrea; Colley, Binta
2006-01-01
The main purpose of this study was to look at how we used specific writing assignments in our courses to encourage metacognitive reflection in order to increase the learning that takes place. The study also aimed to aid in the development of higher order processing skills through the development of student reflection. The students involved in the…
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.
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
Higher-order awareness, misrepresentation and function.
Rosenthal, David
2012-05-19
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
Breastfeeding twins and higher-order multiples.
Gromada, K K; Spangler, A K
1998-01-01
The benefits of breastfeeding for pre-term and full-term infants are well documented. Breastfeeding facilitates maternal-infant attachment, provides optimal infant nutrition and immunologic protection, and minimizes economic impact. These benefits are multiplied with twins and higher-order multiples, who often are born at risk. Supporting a mother as she initiates and continues to breastfeed one infant requires specific knowledge and skills. Health professionals need additional knowledge and skills if they are to provide appropriate assessment, intervention, and support when a mother breastfeeds twins or higher-order multiples. PMID:9684207
Higher-order dielectrophoresis of nonspherical particles
NASA Astrophysics Data System (ADS)
Nili, Hossein; Green, Nicolas G.
2014-06-01
Higher-order terms of dielectrophoretic (DEP) force are commonly ignored by invoking the simplifying dipole approximation. Concurrently, the trend towards micro- and nano-electrode structures in DEP design is bringing about an increasing number of instances where the approximation is expected to lose reliability. The case is severe for nonspherical particles (the shape of many biological particles) due to the shape-dependent nature of dielectric polarization. However, there is a lack of analytical means to determine multipole moments of nonspherical particles, numerical calculations of the same are regarded as unreliable, and there is a prevalence for higher-order force considerations to be ignored. As a result, the dipole approximation is used and/or nonspherical particles are approximated as spheres. This work proves the inefficacy of current qualitative criteria for the reliability of the dipole approximation and presents a quantitative substitute, with verified accuracy, that enables precise determination of the extent to which the dipole approximation would be reliable, and if found unreliable, corrects the approximation by adding second- and third-order terms of the DEP force. The effects of field nonuniformity, electrode design, and particle shape and aspect ratio on the significance of higher-order DEP forces is quantitatively analyzed. The results show that higher-order DEP forces are indeed of substantially increased significance for nonspherical particles; in the cases examined in this work, multipolar terms are seen to constitute more than 40% of the total force on ellipsoidal and cylindrical particles. It is further shown that approximating nonspherical particles as spheres of similar dimensions is subject to substantial error. Last, the substantial importance of the electrode design in influencing higher-order forces is shown.
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…
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. PMID:26263071
Enhanced higher order parametric x radiation production
NASA Astrophysics Data System (ADS)
Dinova, Kay L.
1992-12-01
This thesis examines parametric x-radiation (PXR) which is the Bragg scattering of the virtual photons associated with the Coulomb field of relativistic charged particle from the atomic planes of a crystal. Higher order parametric x-radiation from the (002) planes of a thick mosaic graphite crystal have been observed. The raw PXR data was collected using a SiLi detector and a Pulse Height Analyzer (PHA) software program. The data was corrected for various effects including attenuation, detector drift, and efficiency. The absolute number of photons per electron was obtained by using the fluorescent x-ray yield from a tin foil backing on the graphite crystal to determine the LINAC current. The number of photons per electron observed greatly exceeds the expected values. Comparison of the ratio of intensity of a given order to the first order I(n)/I(I) to the theoretical ratio shows that the ratios increase with order. Not only is the absolute intensity greater than expected, but the higher orders (compared to the first order) are larger than expected. Lastly, the intensity for various crystal angle orientations and a fixed detector angle was measured.
Human Capital, (Human) Capabilities and Higher Education
ERIC Educational Resources Information Center
Le Grange, L.
2011-01-01
In this article I initiate a debate into the (de)merits of human capital theory and human capability theory and discuss implications of the debate for higher education. Human capital theory holds that economic growth depends on investment in education and that economic growth is the basis for improving the quality of human life. Human capable…
The regular state in higher order gravity
NASA Astrophysics Data System (ADS)
Cotsakis, Spiros; Kadry, Seifedine; Trachilis, Dimitrios
2016-08-01
We consider the higher-order gravity theory derived from the quadratic Lagrangian R + 𝜖R2 in vacuum as a first-order (ADM-type) system with constraints, and build time developments of solutions of an initial value formulation of the theory. We show that all such solutions, if analytic, contain the right number of free functions to qualify as general solutions of the theory. We further show that any regular analytic solution which satisfies the constraints and the evolution equations can be given in the form of an asymptotic formal power series expansion.
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. PMID:24518581
Hydrogen peroxide mediates higher order chromatin degradation.
Bai, H; Konat, G W
2003-01-01
Although a large body of evidence supports a causative link between oxidative stress and neurodegeneration, the mechanisms are still elusive. We have recently demonstrated that hydrogen peroxide (H(2)O(2)), the major mediator of oxidative stress triggers higher order chromatin degradation (HOCD), i.e. excision of chromatin loops at the matrix attachment regions (MARs). The present study was designed to determine the specificity of H(2)O(2) in respect to HOCD induction. Rat glioma C6 cells were exposed to H(2)O(2) and other oxidants, and the fragmentation of genomic DNA was assessed by field inversion gel electrophoresis (FIGE). S1 digestion before FIGE was used to detect single strand fragmentation. The exposure of C6 cells to H(2)O(2) induced a rapid and extensive HOCD. Thus, within 30 min, total chromatin was single strandedly digested into 50 kb fragments. Evident HOCD was elicited by H(2)O(2) at concentrations as low as 5 micro M. HOCD was mostly reversible during 4-8h following the removal of H(2)O(2) from the medium indicating an efficient relegation of the chromatin fragments. No HOCD was induced by H(2)O(2) in isolated nuclei indicating that HOCD-endonuclease is activated indirectly by cytoplasmic signal pathways triggered by H(2)O(2). The exposure of cells to a synthetic peroxide, i.e. tert-butyrylhydroperoxide (tBH) also induced HOCD, but to a lesser extent than H(2)O(2). Contrary to the peroxides, the exposure of cells to equitoxic concentration of hypochlorite and spermine NONOate, a nitric oxide generator, failed to induce rapid HOCD. These results indicate that rapid HOCD is not a result of oxidative stress per se, but is rather triggered by signaling cascades initiated specifically by H(2)O(2). Furthermore, the rapid and extensive HOCD was observed in several rat and human cell lines challenged with H(2)O(2), indicating that the process is not restricted to glial cells, but rather represents a general response of cells to H(2)O(2). PMID:12421592
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
Discrimination of higher-order textures.
Nothdurft, H C
1985-01-01
Arrays of figural elements differing in certain features ('textons') may be visually segregated to yield the impression of a global figure of different texture. This fact was used to construct texture patterns of a higher level of complexity. In microstructure, these patterns reveal regular arrays of distinguishable figural elements, the segregation of which can be predicted from previous studies of human texture sensitivity. In macrostructure, clusters of such elements form new figural elements which, when repeated over space, themselves give the impression of texture at a perceptually higher level. Discrimination of such macrostructure textures was found to place similar restrictions on the form of figural elements as those of texture discrimination at the microstructure level. PMID:3836385
A Novel Higher Order Artificial Neural Networks
NASA Astrophysics Data System (ADS)
Xu, Shuxiang
2010-05-01
In this paper a new Higher Order Neural Network (HONN) model is introduced and applied in several data mining tasks. Data Mining extracts hidden patterns and valuable information from large databases. A hyperbolic tangent function is used as the neuron activation function for the new HONN model. Experiments are conducted to demonstrate the advantages and disadvantages of the new HONN model, when compared with several conventional Artificial Neural Network (ANN) models: Feedforward ANN with the sigmoid activation function; Feedforward ANN with the hyperbolic tangent activation function; and Radial Basis Function (RBF) ANN with the Gaussian activation function. The experimental results seem to suggest that the new HONN holds higher generalization capability as well as abilities in handling missing data.
Finesky -- removing higher order sky residuals
NASA Astrophysics Data System (ADS)
Dahlen, Tomas; Grumm, David
2010-07-01
We report on a new IRAF task called finesky that removes higher order sky residuals in NICMOS images by creating a masked median image of the observed sky. This median sky image is thereafter subtracted from the science images. A residual signal after image processing using the calibration software calnica may be present due to reference files that do not sufficiently match the conditions of the observations. This includes a slight mismatch in the dark current or the flat-field corrections. The task described here can also used to create sky flat-field images.
Higher-order brane gravity models
Dabrowski, Mariusz P.; Balcerzak, Adam
2010-06-23
We discuss a very general theory of gravity, of which Lagrangian is an arbitrary function of the curvature invariants, on the brane. In general, the formulation of the junction conditions (except for Euler characteristics such as Gauss-Bonnet term) leads to the powers of the delta function and requires regularization. We suggest the way to avoid such a problem by imposing the metric and its first derivative to be regular at the brane, the second derivative to have a kink, the third derivative of the metric to have a step function discontinuity, and no sooner as the fourth derivative of the metric to give the delta function contribution to the field equations. Alternatively, we discuss the reduction of the fourth-order gravity to the second order theory by introducing extra scalar and tensor fields: the scalaron and the tensoron. In order to obtain junction conditions we apply two methods: the application of the Gauss-Codazzi formalism and the application of the generalized Gibbons-Hawking boundary terms which are appended to the appropriate actions. In the most general case we derive junction conditions without assuming the continuity of the scalaron and the tensoron on the brane. The derived junction conditions can serve studying the cosmological implications of the higher-order brane gravity models.
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.
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…
Higher Order Thermal Lattice Boltzmann Model
NASA Astrophysics Data System (ADS)
Sorathiya, Shahajhan; Ansumali, Santosh
2013-03-01
Lattice Boltzmann method (LBM) modelling of thermal flows, compressible and micro flows requires an accurate velocity space discretization. The sub optimality of Gauss-Hermite quadrature in this regard is well known. Most of the thermal LBM in the past have suffered from instability due to lack of proper H-theorem and accuracy. Motivated from these issues, the present work develops along the two works and and imposes an eighth higher order moment to get correct thermal physics. We show that this can be done by adding just 6 more velocities to D3Q27 model and obtain a ``multi-speed on lattice thermal LBM'' with 33 velocities in 3D and calO (u4) and calO (T4) accurate fieq with a consistent H-theorem and inherent numerical stability. Simulations for Rayleigh-Bernard as well as velocity and temperature slip in micro flows matches with analytical results. Lid driven cavity set up for grid convergence is studied. Finally, a novel data structure is developed for HPC. The authors express their gratitude for computational resources and financial support provide by Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India.
Higher-order motion sensitivity in fly visual circuits.
Lee, Yu-Jen; Nordström, Karin
2012-05-29
In higher-order motion stimuli, the direction of object motion does not follow the direction of luminance change. Such stimuli could be generated by the wing movements of a flying butterfly and further complicated by its motion in and out of shadows. Human subjects readily perceive the direction of higher-order motion, although this stands in stark contrast to prevailing motion vision models. Flies and humans compute motion in similar ways, and because flies behaviorally track bars containing higher-order motion cues, they become an attractive model system for investigating the neurophysiology underlying higher-order motion sensitivity. We here use intracellular electrophysiology of motion-vision-sensitive neurons in the hoverfly lobula plate to quantify responses to stimuli containing higher-order motion. We show that motion sensitivity can be broken down into two separate streams, directionally coding for elementary motion and figure motion, respectively, and that responses to Fourier and theta motion can be predicted from these. The sensitivity is affected both by the stimulus' time course and by the neuron's underlying receptive field. Responses to preferred-direction theta motion are sexually dimorphic and particularly robust along the visual midline. PMID:22586123
Higher-order motion sensitivity in fly visual circuits
Lee, Yu-Jen; Nordström, Karin
2012-01-01
In higher-order motion stimuli, the direction of object motion does not follow the direction of luminance change. Such stimuli could be generated by the wing movements of a flying butterfly and further complicated by its motion in and out of shadows. Human subjects readily perceive the direction of higher-order motion, although this stands in stark contrast to prevailing motion vision models. Flies and humans compute motion in similar ways, and because flies behaviorally track bars containing higher-order motion cues, they become an attractive model system for investigating the neurophysiology underlying higher-order motion sensitivity. We here use intracellular electrophysiology of motion-vision–sensitive neurons in the hoverfly lobula plate to quantify responses to stimuli containing higher-order motion. We show that motion sensitivity can be broken down into two separate streams, directionally coding for elementary motion and figure motion, respectively, and that responses to Fourier and theta motion can be predicted from these. The sensitivity is affected both by the stimulus’ time course and by the neuron’s underlying receptive field. Responses to preferred-direction theta motion are sexually dimorphic and particularly robust along the visual midline. PMID:22586123
Higher Education Guidelines for Executive Order 11246.
ERIC Educational Resources Information Center
Office for Civil Rights (DHEW), Washington, DC.
This document presents and explains Executive Order 11246, the order prohibiting discrimination under federal contracts in colleges and universities. Part one of the document describes the legal provisions of the order; part two deals with personnel policies and practices including recruitment, hiring, anti-nepotism policies, training, promotion,…
On the higher orders of hyperspherical harmonics
NASA Astrophysics Data System (ADS)
Arribas, E.; Navarro, J.; Fabre de la Ripelle, M.
1983-08-01
We suggest a procedure to evaluate matrix elements between hyperspherical harmonics of any order. The method is based on the hyperspherical expansion of a Slater determinant constructed with oscillator wavefunctions. Explicit formulas are given for all matrix elements up to order Lm+2.
Higher-order corrections in threshold resummation
NASA Astrophysics Data System (ADS)
Moch, S.; Vermaseren, J. A. M.; Vogt, A.
2005-10-01
We extend the threshold resummation exponents G in Mellin- N space to the fourth logarithmic (N 3LL) order collecting the terms αs2( to all orders in the strong coupling constant α. Comparing the results to our previous three-loop calculations for deep-inelastic scattering (DIS), we derive the universal coefficients B and B governing the final-state jet functions to order αs3, extending the previous quark and gluon results by one and two orders. A curious relation is found at second order between these quantities, the splitting functions and the large-angle soft emissions in Drell-Yan type processes. We study the numerical effect of the N 3LL corrections using both the fully exponentiated form and the expansion of the coefficient function in towers of logarithms.
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 HARD EDGE END FIELD EFFECTS.
BERG,J.S.
2004-09-14
In most cases, nonlinearities from magnets must be properly included in tracking and analysis to properly compute quantities of interest, in particular chromatic properties and dynamic aperture. One source of nonlinearities in magnets that is often important and cannot be avoided is the nonlinearity arising at the end of a magnet due to the longitudinal variation of the field at the end of the magnet. Part of this effect is independent of the longitudinal of the end. It is lowest order in the body field of the magnet, and is the result of taking a limit as the length over which the field at the end varies approaches zero. This is referred to as a ''hard edge'' end field. This effect has been computed previously to lowest order in the transverse variables. This paper describes a method to compute this effect to arbitrary order in the transverse variables, under certain constraints.
Simulation Higher Order Language Requirements Study.
ERIC Educational Resources Information Center
Goodenough, John B.; Braun, Christine L.
The definitions provided for high order language (HOL) requirements for programming flight training simulators are based on the analysis of programs written for a variety of simulators. Examples drawn from these programs are used to justify the need for certain HOL capabilities. A description of the general structure and organization of the…
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.
Invariant Higher-Order Variational Problems II
NASA Astrophysics Data System (ADS)
Gay-Balmaz, François; Holm, Darryl D.; Meier, David M.; Ratiu, Tudor S.; Vialard, François-Xavier
2012-08-01
Motivated by applications in computational anatomy, we consider a second-order problem in the calculus of variations on object manifolds that are acted upon by Lie groups of smooth invertible transformations. This problem leads to solution curves known as Riemannian cubics on object manifolds that are endowed with normal metrics. The prime examples of such object manifolds are the symmetric spaces. We characterize the class of cubics on object manifolds that can be lifted horizontally to cubics on the group of transformations. Conversely, we show that certain types of non-horizontal geodesic on the group of transformations project to cubics. Finally, we apply second-order Lagrange-Poincaré reduction to the problem of Riemannian cubics on the group of transformations. This leads to a reduced form of the equations that reveals the obstruction for the projection of a cubic on a transformation group to again be a cubic on its object manifold.
Moral Order and the Humanities.
ERIC Educational Resources Information Center
Howard, Thomas
1980-01-01
Argues that a society without reverence for myths and history inevitably falls prone to chaos and evil, pointing to abortion, Andy Warhol's celebrity, and Woodstock as evidence of this disintegration of society. Proposes that humanities education expose students to human experience based on some awesome and fixed moral order. (AYC)
Higher Order Macro Coefficients in Periodic Homogenization
NASA Astrophysics Data System (ADS)
Conca, Carlos; San Martin, Jorge; Smaranda, Loredana; Vanninathan, Muthusamy
2011-09-01
A first set of macro coefficients known as the homogenized coefficients appear in the homogenization of PDE on periodic structures. If energy is increased or scale is decreased, these coefficients do not provide adequate approximation. Using Bloch decomposition, it is first realized that the above coefficients correspond to the lowest energy and the largest scale. This naturally paves the way to introduce other sets of macro coefficients corresponding to higher energies and lower scales which yield better approximation. The next task is to compare their properties with those of the homogenized coefficients. This article reviews these developments along with some new results yet to be published.
Higher-order terms in mode conversion
NASA Astrophysics Data System (ADS)
Swanson, D. G.
1998-07-01
The development of model equations to describe mode conversion and tunneling in an inhomogeneous plasma usually uses expansions of the Modified Bessel functions in the parameter λ=1/2k⊥2ρL2, keeping only the lowest possible order to demonstrate tunneling. With the high temperatures of fusion parameters, especially for fusion alpha particles, this parameter may not be small. It is shown here that the effective expansion parameter is really βj=2μ0njkTj/B02, the ratio of plasma pressure to the magnetic pressure.
Systems with Higher-Order Modulation
NASA Astrophysics Data System (ADS)
Seimetz, Matthias
With the objective of reducing costs per information bit in optical communication networks, per fibre capacities and optical transparent transmission lengths have been stepped up by the introduction of new technology in recent years. The innovation of the erbium-doped fibre amplifier (EDFA) at the beginning of the nineties facilitated long distances to be bridged without electro-optical conversion. Wavelength division multiplexing (WDM) technology allowed a lot of wavelength channels to be simultaneously transmitted over one fibre and to be amplified by one EDFA with high bandwidth, offering a huge network capacity. At this time, the modulation format of choice was the simple "on-off keying" (OOK), and there was no need for increasing spectral efficiency. The internet traffic growth during the nineties required increasing transmission rates. In that context, the transmission impairments of the optical fibre had to be counteracted and the application of differential binary phased shift keying (DBPSK) became an issue, providing for a higher robustness against nonlinear effects [1]. Moreover, the transmission behaviour of binary intensity modulation was optimized by using alternative optical pulse shapes such as return to zero (RZ) and by employing schemes with auxiliary phase coding, such as optical duobinary, which exhibits a higher tolerance against chromatic dispersion (CD). The capacity-distance product was further enhanced by applying optical dispersion compensation, Raman amplification and advanced optical fibres, as well as through electronic means, such as forward error correction (FEC) and the adaptive compensation of CD and polarization mode dispersion (PMD).
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
Higher Order Chromaticity Correction for ELIC
NASA Astrophysics Data System (ADS)
Sayed, Hisham; Bogacz, Alex
2010-02-01
The proposed electron collider lattice design with extremely low betas at the interaction Point IP (β*˜ 0.5cm) and the precedently large longitudinal acceptance of the collider ring (δp/p = 0.005) [1], makes the chromatic corrections of paramount importance. Here the chromatic effects of the final focus quadruples are corrected with two families of sextuples in a dispersive region; one family per plane. Each family consists of two pairs of sextuples located symmetrically around the interaction point IP. A confined dispersion wave around the IP is generated by two bending magnets (one at each side of the IP with mirror reflected Polarities) which also develop the vertical staking design. The resulting spherical aberrations induced by the sextuples are mitigated by design; the matching section optics features an inverse identity transformation between sextuples in each pair. A dedicated optics is placed in the matching region to implement sextuple orthogonality in both planes, which in turns minimizes the required sextuple strength and eventually leads to larger dynamic aperture of the collider. The betatron phase advances from the IP to the sextuples are chosen to eliminate the second order chromatic aberration. )
Higher-Order Spectrum in Understanding Nonlinearity in EEG Rhythms
Pradhan, Cauchy; Jena, Susant K.; Nadar, Sreenivasan R.; Pradhan, N.
2012-01-01
The fundamental nature of the brain's electrical activities recorded as electroencephalogram (EEG) remains unknown. Linear stochastic models and spectral estimates are the most common methods for the analysis of EEG because of their robustness, simplicity of interpretation, and apparent association with rhythmic behavioral patterns in nature. In this paper, we extend the use of higher-order spectrum in order to indicate the hidden characteristics of EEG signals that simply do not arise from random processes. The higher-order spectrum is an extension Fourier spectrum that uses higher moments for spectral estimates. This essentially nullifies all Gaussian random effects, therefore, can reveal non-Gaussian and nonlinear characteristics in the complex patterns of EEG time series. The paper demonstrates the distinguishing features of bispectral analysis for chaotic systems, filtered noises, and normal background EEG activity. The bispectrum analysis detects nonlinear interactions; however, it does not quantify the coupling strength. The squared bicoherence in the nonredundant region has been estimated to demonstrate nonlinear coupling. The bicoherence values are minimal for white Gaussian noises (WGNs) and filtered noises. Higher bicoherence values in chaotic time series and normal background EEG activities are indicative of nonlinear coupling in these systems. The paper shows utility of bispectral methods as an analytical tool in understanding neural process underlying human EEG patterns. PMID:22400046
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…
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.
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.
Quantifying higher-order correlations in a neuronal pool
NASA Astrophysics Data System (ADS)
Montangie, Lisandro; Montani, Fernando
2015-03-01
Recent experiments involving a relatively large population of neurons have shown a very significant amount of higher-order correlations. However, little is known of how these affect the integration and firing behavior of a population of neurons beyond the second order statistics. To investigate how higher-order inputs statistics can shape beyond pairwise spike correlations and affect information coding in the brain, we consider a neuronal pool where each neuron fires stochastically. We develop a simple mathematically tractable model that makes it feasible to account for higher-order spike correlations in a neuronal pool with highly interconnected common inputs beyond second order statistics. In our model, correlations between neurons appear from q-Gaussian inputs into threshold neurons. The approach constitutes the natural extension of the Dichotomized Gaussian model, where the inputs to the model are just Gaussian distributed and therefore have no input interactions beyond second order. We obtain an exact analytical expression for the joint distribution of firing, quantifying the degree of higher-order spike correlations, truly emphasizing the functional aspects of higher-order statistics, as we account for beyond second order inputs correlations seen by each neuron within the pool. We determine how higher-order correlations depend on the interaction structure of the input, showing that the joint distribution of firing is skewed as the parameter q increases inducing larger excursions of synchronized spikes. We show how input nonlinearities can shape higher-order correlations and enhance coding performance by neural populations.
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…
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.
Higher Order Modeling In the BEM/FEM Hybrid Formulation
NASA Technical Reports Server (NTRS)
Fink, Patrick W.; Wilton, Don R.
2000-01-01
Hybrid formulations using low order curl-conforming bases to represent the total electric field within a finite element region and low order divergence-conforming bases to represent equivalent electric and magnetic currents on the boundary are well known. However, higher-order divergence and curl-conforming bases have been shown to provide significant benefits in convergence rates and accuracy when employed in strictly integral equation and strictly finite element formulations. In this paper, a hybrid electric field formulation employing higher order bases is presented. The paper addresses benefits and issues associated with using higher order divergence-and curl-conforming bases in the hybrid finite element/boundary element electric field formulation. The method of singularity subtraction may be used to compute the self terms of the boundary integral when the bases are of low order. But this method becomes laborious and requires great care when the divergence conforming bases are of higher order. In order to handle these singularities simply and accurately, a generalized Gaussian quadrature method is employed in which the expansion functions account for the singularity. In preliminary tests of the higher order hybrid formulation, the equivalent electric current induced by scattering of a plane wave from a square dielectric cylinder is examined. Accurate results are obtained using only a two-triangle mesh when the current basis is of order 4 or 5. Additional results are presented comparing the error obtained using higher order bases to that obtained using lower order bases when the number of unknowns is approximately equal. Also, convergence rates obtained with higher order bases are compared to those obtained with lower order bases for selected sample problems.
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.
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.
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. PMID:26391126
On higher order geometric and renormalization group flows
NASA Astrophysics Data System (ADS)
Prabhu, Kartik; Das, Sanjit; Kar, Sayan
2011-10-01
Renormalization group (RG) flows of the bosonic nonlinear σ-model are governed, perturbatively, at different orders of α', by perturbatively evaluated β-functions. In regions where {α'}/{Rc2}≪1 ( {1}/{Rc2} represents the curvature scale), the flow equations at various orders in α' can be thought of as approximating the full, non-perturbative RG flow. On the other hand, taking a different viewpoint, we may consider the above-mentioned RG flow equations as viable geometric flows in their own right, without any reference to the RG aspect. Looked at as purely geometric flows where higher order terms appear, we no longer have the perturbative restrictions (small curvatures). In this paper, we perform our analysis from both these perspectives using specific target manifolds such as S2, H2, unwarped S2×H2 and simple warped products. We analyse and solve the higher order RG flow equations within the appropriate perturbative domains and find the corrections arising due to the inclusion of higher order terms. Such corrections, within the perturbative regime, are shown to be small and they provide an estimate of the error that arises when higher orders are ignored. We also investigate higher order geometric flows on the same manifolds and figure out generic features of geometric evolution, the appearance of singularities and solitons. The aim, in this context, is to demonstrate the role of higher order terms in modifying the flow. One interesting aspect of our analysis is that, separable solutions of the higher order flow equations for simple warped spacetimes (of the kind used in bulk-brane models with a single extra dimension), correspond to constant curvature anti de Sitter (AdS) spacetimes, modulo an overall flow parameter dependent scale factor. The functional form of this scale factor (that we obtain) changes on the inclusion of successive higher order terms in the flow.
A Testing Theory for a Higher-Order Cryptographic Language
NASA Astrophysics Data System (ADS)
Koutavas, Vasileios; Hennessy, Matthew
We study a higher-order concurrent language with cryptographic primitives, for which we develop a sound and complete, first-order testing theory for the preservation of safety properties. Our theory is based on co-inductive set simulations over transitions in a first-order Labelled Transition System. This keeps track of the knowledge of the observer, and treats transmitted higher-order values in a symbolic manner, thus obviating the quantification over functional contexts. Our characterisation provides an attractive proof technique, and we illustrate its usefulness in proofs of equivalence, including cases where bisimulation theory does not apply.
Superposition rules for higher order systems and their applications
NASA Astrophysics Data System (ADS)
Cariñena, J. F.; Grabowski, J.; de Lucas, J.
2012-05-01
Superposition rules form a class of functions that describe general solutions of systems of first-order ordinary differential equations in terms of generic families of particular solutions and certain constants. In this work, we extend this notion and other related ones to systems of higher order differential equations and analyse their properties. Several results concerning the existence of various types of superposition rules for higher order systems are proved and illustrated with examples extracted from the physics and mathematics literature. In particular, two new superposition rules for the second- and third-order Kummer-Schwarz equations are derived.
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.
On the Evaluation of Higher-Order Science Instructional Objectives
ERIC Educational Resources Information Center
Hambleton, Ronald K.; Sheehan, Daniel S.
1977-01-01
Advocates the use of a free-sort categorization technique for evaluation of higher-order science instructional objectives. An explanation and demonstration of the use of the evaluation technique with 284 ninth-grade science students is provided. (CP)
Chromatin higher-order structures and gene regulation
Li, Guohong
2011-01-01
Genomic DNA in the eukaryotic nucleus is hierarchically packaged by histones into chromatin to fit inside the nucleus. The dynamics of higher-order chromatin compaction play a critical role in transcription and other biological processes inherent to DNA. Many factors, including histone variants, histone modifications, DNA methylation and the binding of non-histone architectural proteins regulate the structure of chromatin. Although the structure of nucleosomes, the fundamental repeating unit of chromatin, is clear, there is still much discussion on the higher-order levels of chromatin structure. In this review, we focus on the recent progress in elucidating the structure of the 30-nm chromatin fiber. We also discuss the structural plasticity/dynamics and epigenetic inheritance of higher-order chromatin and the roles of chromatin higher-order organization in eukaryotic gene regulation. PMID:21342762
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
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.
Higher order derivatives of R-Jacobi polynomials
NASA Astrophysics Data System (ADS)
Das, Sourav; Swaminathan, A.
2016-06-01
In this work, the R-Jacobi polynomials defined on the nonnegative real axis related to F-distribution are considered. Using their Sturm-Liouville system higher order derivatives are constructed. Orthogonality property of these higher ordered R-Jacobi polynomials are obtained besides their normal form, self-adjoint form and hypergeometric representation. Interesting results on the Interpolation formula and Gaussian quadrature formulae are obtained with numerical examples.
Feynman rules of higher-order poles in CHY construction
NASA Astrophysics Data System (ADS)
Huang, Rijun; Feng, Bo; Luo, Ming-xing; Zhu, Chuan-Jie
2016-06-01
In this paper, we generalize the integration rules for scattering equations to situations where higher-order poles are present. We describe the strategy to deduce the Feynman rules of higher-order poles from known analytic results of simple CHY-integrands, and propose the Feynman rules for single double pole and triple pole as well as duplex-double pole and triplex-double pole structures. We demonstrate the validation and strength of these rules by ample non-trivial examples.
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.
Unified formalism for higher order non-autonomous dynamical systems
NASA Astrophysics Data System (ADS)
Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso
2012-03-01
This work is devoted to giving a geometric framework for describing higher order non-autonomous mechanical systems. The starting point is to extend the Lagrangian-Hamiltonian unified formalism of Skinner and Rusk for these kinds of systems, generalizing previous developments for higher order autonomous mechanical systems and first-order non-autonomous mechanical systems. Then, we use this unified formulation to derive the standard Lagrangian and Hamiltonian formalisms, including the Legendre-Ostrogradsky map and the Euler-Lagrange and the Hamilton equations, both for regular and singular systems. As applications of our model, two examples of regular and singular physical systems are studied.
Higher-order conditioning and the retrosplenial cortex.
Todd, Travis P; Huszár, Roman; DeAngeli, Nicole E; Bucci, David J
2016-09-01
The retrosplenial cortex (RSC) is known to contribute to contextual and spatial learning and memory. This is consistent with its well-established connectivity; the RSC is located at the interface of visuo-spatial association areas and the parahippocampal-hippocampal memory system. However, the RSC also contributes to learning and memory for discrete cues. For example, both permanent lesions and temporary inactivation of the RSC have been shown to impair sensory preconditioning, a form of higher-order conditioning. The purpose of the present experiment was to examine the role of the RSC in a closely related higher-order conditioning paradigm: second-order conditioning. Sham and RSC lesioned rats received first-order conditioning in which one visual stimulus (V1) was paired with footshock and one visual stimulus (V2) was not. Following first-order conditioning, one auditory stimulus (A1) was then paired with V1 and a second auditory stimulus (A2) was paired with V2. Although lesions of the RSC impaired the first-order discrimination, they had no impact on the acquisition of second-order conditioning. Thus, the RSC does not appear necessary for acquisition/expression of second-order fear conditioning. The role of the RSC in higher-order conditioning, as well as a possible dissociation from the hippocampus, is discussed. PMID:27208598
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
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;…
Optimized higher-order automatic differentiation for the Faddeeva function
NASA Astrophysics Data System (ADS)
Charpentier, Isabelle
2016-08-01
Considerable research efforts have been directed at implementing the Faddeeva function w(z) and its derivatives with respect to z, but these did not consider the key computing issue of a possible dependence of z on some variable t. The general case is to differentiate the compound function w(z(t)) = w ∘ z(t) with respect to t by applying the chain rule for a first order derivative, or Faà di Bruno's formula for higher-order ones. Higher-order automatic differentiation (HOAD) is an efficient and accurate technique for derivative calculation along scientific computing codes. Although codes are available for w(z) , a special symbolic HOAD is required to compute accurate higher-order derivatives for w ∘ z(t) in an efficient manner. A thorough evaluation is carried out considering a nontrivial case study in optics to support this assertion.
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.
LOCAL ANISOTROPY, HIGHER ORDER STATISTICS, AND TURBULENCE SPECTRA
Matthaeus, W. H.; Wan, M.; Osman, K. T.; Servidio, S.; Carbone, V.; Dmitruk, P.; Oughton, S.
2012-05-10
Correlation anisotropy emerges dynamically in magnetohydrodynamics (MHD), producing stronger gradients across the large-scale mean magnetic field than along it. This occurs both globally and locally, and has significant implications in space and astrophysical plasmas, including particle scattering and transport, and theories of turbulence. Properties of local correlation anisotropy are further documented here by showing through numerical experiments that the effect is intensified in more localized estimates of the mean field. The mathematical formulation of this property shows that local anisotropy mixes second-order with higher order correlations. Sensitivity of local statistical estimates to higher order correlations can be understood in connection with the stochastic coordinate system inherent in such formulations. We demonstrate this in specific cases, and illustrate the connection to higher order statistics by showing the sensitivity of local anisotropy to phase randomization, after which the global measure of anisotropy is recovered at all scales of averaging. This establishes that anisotropy of the local structure function is not a measure of anisotropy of the energy spectrum. Evidently, the local enhancement of correlation anisotropy is of substantial fundamental interest and must be understood in terms of higher order correlations, specifically fourth-order and above.
Symplectic representation of higher-order guiding-center theory
NASA Astrophysics Data System (ADS)
Brizard, Alain; Tronko, Natalia
2012-03-01
Two representations of guiding-center theory are possible depending on whether the guiding-center Poisson bracket (i.e., the symplectic structure) or the Hamiltonian contains higher-order corrections due to the nonuniformity of the magnetic field. By combining the guiding-center parallel hierarchy with the symplectic representation, the guiding-center equations of motion are derived with second-order corrections included in the symplectic structure without the need of carrying out the guiding-center transformation to second order. Guiding-center polarization and magnetization are thus shown to arise naturally from higher-order guiding-center theory within the context of a two-step derivation of nonlinear gyrokinetic theory.footnotetextA. J. Brizard and T. S. Hahm, Rev. Mod. Phys. 79, 421 (2007).
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.
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.
Breaking the symmetry for enhanced higher-order mode delocalization
NASA Astrophysics Data System (ADS)
Stutzki, Fabian; Jansen, Florian; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas
2014-03-01
Large-pitch fibers (LPFs) have enabled the current records for average power, pulse energy and pulse peak power in ultra-fast fiber laser systems. In this paper the working principle of LPFs, which is based on higher-order mode delocalization, is numerically analyzed paying special attention to thermal effects and index mismatch. An enhanced design concept is proposed with a reduced symmetry to improve the delocalization of higher-order modes. This enhanced design has been obtained by transferring the most important characteristics of spiral geometries to a common hexagonal lattice.
Higher order mode laser beam scintillations in oceanic medium
NASA Astrophysics Data System (ADS)
Baykal, Yahya
2016-01-01
In a horizontal oceanic optical wireless communication link, the scintillation index (the measure for the intensity fluctuations) of the received intensity caused by the oceanic turbulence is formulated and evaluated when the source is a higher order mode laser. Variations in the scintillation index vs. the underwater turbulence parameters, size of the higher order mode laser source, link length, and the wavelength are examined. Underwater turbulence parameters are the ratio that determines the relative strength of temperature and salinity in driving the index fluctuations, the rate of dissipation of the mean squared temperature, the rate of dissipation of the turbulent kinetic energy, and the Kolmogorov microscale length.
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.
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. PMID:25227016
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.
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…
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.
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
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.
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…
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…
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…
Using Higher-Order Skills in American History.
ERIC Educational Resources Information Center
Litogot, Sandra A.
1991-01-01
Provides a six-part lesson plan for use in secondary U.S. history classes. Illustrates the development of higher-order reading, writing, and thinking skills in assignments and projects dealing with the history of westward expansion. Specific skills addressed are comparison, contrast, prediction, and evaluation. Recommends cooperative learning…
Using Database Projects To Promote Higher-Order Thinking Skills.
ERIC Educational Resources Information Center
Lytle, Cora
1999-01-01
Explains how the process of creating a database provides opportunities for business instructors to use teaching strategies that promote higher-order thinking skills. Describes a project at a school of business in which each student must build an original database and apply functions of tables, queries, forms, and reports. (JOW)
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
Assessing the Influence of Portfolios on Higher Order Thinking Skills.
ERIC Educational Resources Information Center
Seiter, David M.
How the use of portfolios in the classroom will influence the higher order thinking skills is the main focus of this project. The introduction of portfolios as assessment tools is rather new to educational research, but does offer a legitimate area for serious study. Portfolios when used by students can offer them not only a way to showcase their…
Multiple-Try Feedback and Higher-Order Learning Outcomes
ERIC Educational Resources Information Center
Clariana, Roy B.; Koul, Ravinder
2005-01-01
Although feedback is an important component of computer-based instruction (CBI), the effects of feedback on higher-order learning outcomes are not well understood. Several meta-analyses provide two rules of thumb: any feedback is better than no feedback and feedback with more information is better than feedback with less information. …
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.…
Fostering Higher-Order Thinking in Science Class: Teachers' Reflections
ERIC Educational Resources Information Center
Barak, Moshe; Shakhman, Larisa
2008-01-01
The study reported in this article aimed at exploring what teachers know and do about fostering higher-order thinking skills in teaching science, and how they see themselves involved in achieving this end. Data were collected through semi-structured interviews with 11 teachers experienced in teaching high school physics, which is considered a…
Higher-order ionospheric error at Arecibo, Millstone, and Jicamarca
NASA Astrophysics Data System (ADS)
Matteo, N. A.; Morton, Y. T.
2010-12-01
The ionosphere is a dominant source of Global Positioning System receiver range measurement error. Although dual-frequency receivers can eliminate the first-order ionospheric error, most second- and third-order errors remain in the range measurements. Higher-order ionospheric error is a function of both electron density distribution and the magnetic field vector along the GPS signal propagation path. This paper expands previous efforts by combining incoherent scatter radar (ISR) electron density measurements, the International Reference Ionosphere model, exponential decay extensions of electron densities, the International Geomagnetic Reference Field, and total electron content maps to compute higher-order error at ISRs in Arecibo, Puerto Rico; Jicamarca, Peru; and Millstone Hill, Massachusetts. Diurnal patterns, dependency on signal direction, seasonal variation, and geomagnetic activity dependency are analyzed. Higher-order error is largest at Arecibo with code phase maxima circa 7 cm for low-elevation southern signals. The maximum variation of the error over all angles of arrival is circa 8 cm.
Speckle reduction via higher order total variation approach.
Wensen Feng; Hong Lei; Yang Gao
2014-04-01
Multiplicative noise (also known as speckle) reduction is a prerequisite for many image-processing tasks in coherent imaging systems, such as the synthetic aperture radar. One approach extensively used in this area is based on total variation (TV) regularization, which can recover significantly sharp edges of an image, but suffers from the staircase-like artifacts. In order to overcome the undesirable deficiency, we propose two novel models for removing multiplicative noise based on total generalized variation (TGV) penalty. The TGV regularization has been mathematically proven to be able to eliminate the staircasing artifacts by being aware of higher order smoothness. Furthermore, an efficient algorithm is developed for solving the TGV-based optimization problems. Numerical experiments demonstrate that our proposed methods achieve state-of-the-art results, both visually and quantitatively. In particular, when the image has some higher order smoothness, our methods outperform the TV-based algorithms. PMID:24808350
Higher-order structure of Saccharomyces cerevisiae chromatin
Lowary, P.T.; Widom, J. )
1989-11-01
We have developed a method for partially purifying chromatin from Saccharomyces cerevisiae (baker's yeast) to a level suitable for studies of its higher-order folding. This has required the use of yeast strains that are free of the ubiquitous yeast killer virus. Results from dynamic light scattering, electron microscopy, and x-ray diffraction show that the yeast chromatin undergoes a cation-dependent folding into 30-nm filaments that resemble those characteristic of higher-cell chromatin; moreover, the packing of nucleosomes within the yeast 30-nm filaments is similar to that of higher cells. These results imply that yeast has a protein or protein domain that serves the role of the histone H 1 found in higher cells; physical and genetic studies of the yeast activity could help elucidate the structure and function of H 1. Images of the yeast 30-nm filaments can be used to test crossed-linker models for 30-nm filament structure.
Higher order corrections in minimal supergravity models of inflation
Ferrara, Sergio; Kallosh, Renata; Linde, Andrei; Porrati, Massimo E-mail: kallosh@stanford.edu E-mail: massimo.porrati@nyu.edu
2013-11-01
We study higher order corrections in new minimal supergravity models of a single scalar field inflation. The gauging in these models leads to a massive vector multiplet and the D-term potential for the inflaton field with a coupling g{sup 2} ∼ 10{sup −10}. In the de-Higgsed phase with vanishing g{sup 2}, the chiral and vector multiplets are non-interacting, and the potential vanishes. We present generic manifestly supersymmetric higher order corrections for these models. In particular, for a supersymmetric gravity model −R+R{sup 2} we derive manifestly supersymmetric corrections corresponding to R{sup n}. The dual version corresponds to a standard supergravity model with a single scalar and a massive vector. It includes, in addition, higher Maxwell curvature/scalar interaction terms of the Born-Infeld type and a modified D-term scalar field potential. We use the dual version of the model to argue that higher order corrections do not affect the last 60 e-foldings of inflation; for example the ξR{sup 4} correction is irrelevant as long as ξ < 10{sup 24}.
Synchronous firing and higher-order interactions in neuron pool.
Amari, Shun-Ichi; Nakahara, Hiroyuki; Wu, Si; Sakai, Yutaka
2003-01-01
The stochastic mechanism of synchronous firing in a population of neurons is studied from the point of view of information geometry. Higher-order interactions of neurons, which cannot be reduced to pairwise correlations, are proved to exist in synchronous firing. In a neuron pool where each neuron fires stochastically, the probability distribution q(r) of the activity r, which is the fraction of firing neurons in the pool, is studied. When q(r) has a widespread distribution, in particular, when q(r) has two peaks, the neurons fire synchronously at one time and are quiescent at other times. The mechanism of generating such a probability distribution is interesting because the activity r is concentrated on its mean value when each neuron fires independently, because of the law of large numbers. Even when pairwise interactions, or third-order interactions, exist, the concentration is not resolved. This shows that higher-order interactions are necessary to generate widespread activity distributions. We analyze a simple model in which neurons receive common overlapping inputs and prove that such a model can have a widespread distribution of activity, generating higher-order stochastic interactions. PMID:12590822
Higher order correlation beams in atmosphere under strong turbulence conditions.
Avetisyan, H; Monken, C H
2016-02-01
Higher order correlation beams, that is, two-photon beams obtained from the process of spontaneous parametric down-conversion pumped by Hermite-Gauss or Laguerre-Gauss beams of any order, can be used to encode information in many modes, opening the possibility of quantum communication with large alphabets. In this paper we calculate, analytically, the fourth-order correlation function for the Hermite-Gauss and Laguerre-Gauss coherent and partially coherent correlation beams propagating through a strong turbulent medium. We show that fourth-order correlation functions for correlation beams have, under certain conditions, expressions similar to those of intensities of classical beams and are degraded by turbulence in a similar way as the classical beams. Our results can be useful in establishing limits for the use of two-photon beams in quantum communications with larger alphabets under atmospheric turbulence. PMID:26906808
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.
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.
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.
Analytical formulas for gravitational lensing: Higher order calculation
Amore, Paolo; Arceo, Santiago; Fernandez, Francisco M.
2006-10-15
We extend to higher order a recently published method for calculating the deflection angle of light in a general static and spherically symmetric metric. We have tested our method on the metric of Schwarzschild and Reissner-Nordstroem black holes, on the metric of a charged black hole coupled to Born-Infeld electrodynamics and on the metric of Weyl gravity. Since our method is geometrically convergent, as proved in our previous work, our analytical formulas obtained working to fourth order are sufficient to reach errors of few percents even in proximity of the photon sphere.
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 notemore » 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.« less
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.
Algorithmic and Experimental Computation of Higher-Order Safe Primes
NASA Astrophysics Data System (ADS)
Díaz, R. Durán; Masqué, J. Muñoz
2008-09-01
This paper deals with a class of special primes called safe primes. In the regular definition, an odd prime p is safe if, at least, one of (p±1)/2 is prime. Safe primes have been recommended as factors of RSA moduli. In this paper, the concept of safe primes is extended to higher-order safe primes, and an explicit formula to compute the density of this class of primes in the set of the integers is supplied. Finally, explicit conditions are provided permitting the algorithmic computation of safe primes of arbitrary order. Some experimental results are provided as well.
High Precision Superconducting Cavity Diagnostics With Higher Order Mode Measurements
Molloy, S.; Frisch, J.; McCormick, D.; May, J.; Ross, M.; Smith, T.; Baboi, N.; Hensler, O.; Petrosian, L.; Napoly, O.; Paparella, R.C.; Simon, C.; Eddy, N.; Nagaitsev, S.; Wendt, M.; /Fermilab
2007-02-12
Experiments at the FLASH facility at DESY have demonstrated that the higher order modes induced in superconducting cavities can be used to provide a variety of beam and cavity diagnostics. The axes of the modes can be determined from the beam orbit that produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used to obtain high resolution beam position information, and the phase of the monopole modes to measure the beam phase relative to the accelerator rf. For most superconducting accelerators, the existing higher order mode couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional beam position monitor.
Stabilization with target oriented control for higher order difference equations
NASA Astrophysics Data System (ADS)
Braverman, Elena; Franco, Daniel
2015-06-01
For a physical or biological model whose dynamics is described by a higher order difference equation un+1 = f (un ,un-1 , … ,u n - k + 1), we propose a version of a target oriented control un+1 = cT + (1 - c) f (un ,un-1 , … ,u n - k + 1), with T ≥ 0, c ∈ [ 0 , 1). In ecological systems, the method incorporates harvesting and recruitment and for a wide class of f, allows to stabilize (locally or globally) a fixed point of f. If a point which is not a fixed point of f has to be stabilized, the target oriented control is an appropriate method for achieving this goal. As a particular case, we consider pest control applied to pest populations with delayed density-dependence. This corresponds to a proportional feedback method, which includes harvesting only, for higher order equations.
Spatial complexity of solutions of higher order partial differential equations
NASA Astrophysics Data System (ADS)
Kukavica, Igor
2004-03-01
We address spatial oscillation properties of solutions of higher order parabolic partial differential equations. In the case of the Kuramoto-Sivashinsky equation ut + uxxxx + uxx + u ux = 0, we prove that for solutions u on the global attractor, the quantity card {x epsi [0, L]:u(x, t) = lgr}, where L > 0 is the spatial period, can be bounded by a polynomial function of L for all \\lambda\\in{\\Bbb R} . A similar property is proven for a general higher order partial differential equation u_t+(-1)^{s}\\partial_x^{2s}u+ \\sum_{k=0}^{2s-1}v_k(x,t)\\partial_x^k u =0 .
Higher order mode excitations in gyro-amplifiers
NASA Astrophysics Data System (ADS)
Nguyen, K. T.; Calame, J. P.; Danly, B. G.; Levush, B.; Garven, M.; Antonsen, T.
2001-05-01
In gyro-devices, a nonlinear output taper is often employed as the transition from the near cutoff radius of the interaction circuit to a much larger output waveguide. The tapers are usually designed to avoid passive mode conversion, and thus do not consider the effect of a bunched beam. However, recent simulations with the self-consistent MAGY code [Botton et al., IEEE Trans. Plasma Sci. 26, 882 (1998)] indicate that higher order mode interactions with the bunched electron beam can substantially compromise the mode purity of the rf output. The interaction in the taper region is traveling wave in nature, and is strongly dependent on the residual beam bunching characteristics resulting from the upstream operating mode interaction. An experiment has been performed to quantify the rf output mode content from a Ka-band gyroklystron. The agreement between salient theoretical and measured rf output characteristics confirms the existence of higher order mode excitation in output tapers as predicted by theory.
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.
Higher-order effects in inclusive electron-nucleus scattering.
Benhar, O.; Fabrocini, A.; Fantoni, S.; Pandharipande, V. R.; Pieper, S. C.; Sick, I.; Physics; INFIN; Univ. of Pisa; SISSA; Univ. of Illinois; SISSA; Univ. Basel
1995-10-05
Higher order corrections in the theory of inclusive scattering of high energy electrons by nuclear matter are studied. They involve at least three nucleons, and are due to: (i) the correlations among the spectator nucleons in matter, and (ii) the Pauli blocking of the scattering of the struck nucleon by a spectator nucleon. Their effect on the cross sections is found to be much smaller than those of the two-nucleon correlation hole and of color transparency.
Validating variational principle for higher order theory of gravity
NASA Astrophysics Data System (ADS)
Ruz, Soumendranath; Sarkar, Kaushik; Sk, Nayem; Sanyal, Abhik Kumar
2015-06-01
Metric variation of higher order theory of gravity requires fixing of the Ricci scalar in addition to the metric tensor at the boundary. Fixing Ricci scalar at the boundary implies that the classical solutions are fixed once and forever to the de Sitter or anti-de Sitter (dS/AdS) solutions. Here, we justify such requirement from the standpoint of Noether symmetry.
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 nonlinear effects in a Josephson parametric amplifier
NASA Astrophysics Data System (ADS)
Kochetov, Bogdan A.; Fedorov, Arkady
2015-12-01
Nonlinearity of the current-phase relationship of a Josephson junction is the key resource for a Josephson parametric amplifier (JPA) as well as for a Josephson traveling-wave parametric amplifier, the only devices in which the quantum limit for added noise has so far been approached at microwave frequencies. A standard approach to describe JPA takes into account only the lowest order (cubic) nonlinearity resulting in a Duffing-like oscillator equation of motion or in a Kerr-type nonlinearity term in the Hamiltonian. In this paper we derive the quantum expression for the gain of JPA including all orders of the Josephson junction nonlinearity in the linear response regime. We then analyze gain saturation effect for stronger signals within a semiclassical approach. Our results reveal nonlinear effects of higher orders and their implications for operation of a JPA.
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.
Jiang, Yijia; Li, Cynthia; Li, Jenny; Gabrielson, John P; Wen, Jie
2015-04-01
Protein therapeutics differ considerably from small molecule drugs because of the presence of higher order structure (HOS), post-translational modifications, inherent molecular heterogeneity, and unique stability profiles. At early stages of development, multiple molecular candidates are often produced for the same biological target. In order to select the most promising molecule for further development, studies are carried out to compare and rank order the candidates in terms of their manufacturability, purity, and stability profiles. This note reports a case study on the use of selected HOS characterization methods for candidate selection and the role of HOS data in identifying potential challenges that may be avoided by selecting the optimal molecular entity for continued development. PMID:25716705
Higher-Order Theory for Functionally Graded Materials
NASA Technical Reports Server (NTRS)
Aboudi, Jacob; Pindera, Marek-Jerzy; Arnold, Steven M.
1999-01-01
This paper presents the full generalization of the Cartesian coordinate-based higher-order theory for functionally graded materials developed by the authors during the past several years. This theory circumvents the problematic use of the standard micromechanical approach, based on the concept of a representative volume element, commonly employed in the analysis of functionally graded composites by explicitly coupling the local (microstructural) and global (macrostructural) responses. The theoretical framework is based on volumetric averaging of the various field quantities, together with imposition of boundary and interfacial conditions in an average sense between the subvolumes used to characterize the composite's functionally graded microstructure. The generalization outlined herein involves extension of the theoretical framework to enable the analysis of materials characterized by spatially variable microstructures in three directions. Specialization of the generalized theoretical framework to previously published versions of the higher-order theory for materials functionally graded in one and two directions is demonstrated. In the applications part of the paper we summarize the major findings obtained with the one-directional and two-directional versions of the higher-order theory. The results illustrate both the fundamental issues related to the influence of microstructure on microscopic and macroscopic quantities governing the response of composites and the technologically important applications. A major issue addressed herein is the applicability of the classical homogenization schemes in the analysis of functionally graded materials. The technologically important applications illustrate the utility of functionally graded microstructures in tailoring the response of structural components in a variety of applications involving uniform and gradient thermomechanical loading.
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.
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.
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.
High Precision SC Cavity alignment Measurements with Higher Order Modes
Molloy, Stephen; Frisch, Josef; Hendrickson, Linda; McCormick, Douglas; May, Justin; Ross, Marc; Smith, Tonee; Eddy, Nathan; Nagaitsev, Sergei; Baboi, Nicoleta; Hensler, Olaf; Petrosyan, Lyudvig; Napoly, Olivier; Paparella, Rita; Simon, Claire; /DSM, DAPNIA, Saclay
2007-06-14
Experiments at the FLASH linac at DESY have demonstrated that the higher order modes (HOMs) induced in superconducting cavities can be used to provide a variety of beam and cavity diagnostics. The centers of the cavities can be determined from the beam orbit which produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used as a high resolution beam position monitor. For most superconducting accelerators, the existing HOM couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional BPM.
Tight focusing of higher orders Laguerre-Gaussian modes
NASA Astrophysics Data System (ADS)
Savelyev, Dmitry A.; Khonina, Svetlana N.; Golub, Ilya
2016-04-01
The spatial redistribution of the contribution of different electric field components provides a decrease in the size of the central focal spot for higher orders Laguerre-Gaussian modes. It was shown that when sharply focusing laser beams with vortex or special binary phase plate, a sub-wavelength light localization of separate vector field components is possible for any polarization type. This fact should be considered for the interaction of laser radiation with materials selectively sensitive to lateral and longitudinal components of the electromagnetic field.
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.
Higher-order laser mode converters with dielectric metasurfaces.
He, Yongli; Liu, Zhenxing; Liu, Yachao; Zhou, Junxiao; Ke, Yougang; Luo, Hailu; Wen, Shuangchun
2015-12-01
A simple and compact converter based on the dielectric metasurface is proposed for the transformation of Gaussian mode to Hermite-Gaussian and Laguerre-Gaussian modes. We establish the relationship between the phase of a desired mode and the local orientation of the optical axis based on the evolution of Pancharatnam-Berry phase on Poincaré sphere. By controlling the local orientation of the optical axis in the dielectric metasurface, we can achieve any desired higher-order laser mode. PMID:26625037
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.
Introduction to Higher Order Spatial Statistics in Cosmology
NASA Astrophysics Data System (ADS)
Szapudi, I.
Higher order spatial statistics characterize non-Gaussian aspects of random fields, which are ubiquitous in cosmology: from the cosmic microwave background (CMB) to the large-scale structure (LSS) of the universe. These random fields are rich in their properties; they can be continuous or discrete; can have one through three, or even more dimensions; their degree of non- Gaussianity ranges from tiny to significant. Yet, there are several techniques and ideas, which are applicable to virtually all cosmological random fields, be it Lyman-a forests, LSS, or CMB.
NASA Technical Reports Server (NTRS)
Sirkis, James S. (Inventor); Sivanesan, Ponniah (Inventor); Venkat, Venki S. (Inventor)
2001-01-01
A Bragg grating sensor for measuring distributed strain and temperature at the same time comprises an optical fiber having a single mode operating wavelength region and below a cutoff wavelength of the fiber having a multimode operating wavelength region. A saturated, higher order Bragg grating having first and second order Bragg conditions is fabricated in the optical fiber. The first order of Bragg resonance wavelength of the Bragg grating is within the single mode operating wavelength region of the optical fiber and the second order of Bragg resonance wavelength is below the cutoff wavelength of the fiber within the multimode operating wavelength region. The reflectivities of the saturated Bragg grating at the first and second order Bragg conditions are less than two orders of magnitude of one another. In use, the first and second order Bragg conditions are simultaneously created in the sensor at the respective wavelengths and a signal from the sensor is demodulated with respect to each of the wavelengths corresponding to the first and second order Bragg conditions. Two Bragg conditions have different responsivities to strain and temperature, thus allowing two equations for axial strain and temperature to be found in terms of the measure shifts in the primary and second order Bragg wavelengths. This system of equations can be solved for strain and temperature.
Aero-optical jitter estimation using higher-order wavefronts
NASA Astrophysics Data System (ADS)
Whiteley, Matthew R.; Goorskey, David J.; Drye, Richard
2013-07-01
Wavefront measurements from wind tunnel or flight testing of an optical system are affected by jitter sources due to the measurement platform, system vibrations, or aero-mechanical buffeting. Depending on the nature of the testing, the wavefront jitter will be a composite of several effects, one of which is the aero-optical jitter; i.e., the wavefront tilt due to random air density fluctuations. To isolate the aero-optical jitter component from recent testing, we have developed an estimation technique that uses only higher-order wavefront measurements to determine the jitter. By analogy with work done previously with free-stream turbulence, we have developed a minimum mean-square error estimator using higher-order wavefront modes to compute the current-frame tilt components through a linear operation. The estimator is determined from computational fluid dynamics evaluation of aero-optical disturbances, but does not depend on the strength of such disturbances. Applying this technique to turret flight test data, we found aero-optical jitter to be 7.7±0.8 μrad and to scale with (ρ/ρSL)M2 (˜1 μrad in the actual test cases examined). The half-power point of the aero-optical jitter variance was found to be ˜2u∞/Dt and to roll off in temporal frequency with a power law between f and f.
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 Parametric Excitation Modes for Spaceborne Quadrupole Mass Spectrometers
NASA Technical Reports Server (NTRS)
Gershman, D. J.; Block, B. P.; Rubin, M.; Benna, M.; Mahaffy, P. R.; Zurbuchen, T. H.
2011-01-01
This paper describes a technique to significantly improve upon the mass peak shape and mass resolution of spaceborne quadrupole mass spectrometers (QMSs) through higher order auxiliary excitation of the quadrupole field. Using a novel multiresonant tank circuit, additional frequency components can be used to drive modulating voltages on the quadrupole rods in a practical manner, suitable for both improved commercial applications and spaceflight instruments. Auxiliary excitation at frequencies near twice that of the fundamental quadrupole RF frequency provides the advantages of previously studied parametric excitation techniques, but with the added benefit of increased sensed excitation amplitude dynamic range and the ability to operate voltage scan lines through the center of upper stability islands. Using a field programmable gate array, the amplitudes and frequencies of all QMS signals are digitally generated and managed, providing a robust and stable voltage control system. These techniques are experimentally verified through an interface with a commercial Pfeiffer QMG422 quadrupole rod system.When operating through the center of a stability island formed from higher order auxiliary excitation, approximately 50% and 400% improvements in 1% mass resolution and peak stability were measured, respectively, when compared with traditional QMS operation. Although tested with a circular rod system, the presented techniques have the potential to improve the performance of both circular and hyperbolic rod geometry QMS sensors.
Laser-Plasma Wakefield Acceleration with Higher Order Laser Modes
Geddes, C. G. R.; Schroeder, C. B.; Cormier-Michel, E.; Mullowney, P.; Paul, K.; Esarey, E.; Cary, J. R.; Leemans, W. P.
2010-11-04
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.
Inhibitory control gains from higher-order cognitive strategy training.
Motes, Michael A; Gamino, Jacquelyn F; Chapman, Sandra B; Rao, Neena K; Maguire, Mandy J; Brier, Matthew R; Kraut, Michael A; Hart, John
2014-02-01
The present study examined the transfer of higher-order cognitive strategy training to inhibitory control. Middle school students enrolled in a comprehension- and reasoning-focused cognitive strategy training program and passive controls participated. The training program taught students a set of steps for inferring essential gist or themes from materials. Both before and after training or a comparable duration in the case of the passive controls, participants completed a semantically cued Go/No-Go task that was designed to assess the effects of depth of semantic processing on response inhibition and components of event-related potentials (ERP) related to response inhibition. Depth of semantic processing was manipulated by varying the level of semantic categorization required for response selection and inhibition. The SMART-trained group showed inhibitory control gains and changes in fronto-central P3 ERP amplitudes on inhibition trials; whereas, the control group did not. The results provide evidence of the transfer of higher-order cognitive strategy training to inhibitory control and modulation of ERPs associated with semantically cued inhibitory control. The findings are discussed in terms of implications for cognitive strategy training, models of cognitive abilities, and education. PMID:24286804
Higher order parametric excitation modes for spaceborne quadrupole mass spectrometers
Gershman, D. J.; Block, B. P.; Rubin, M.; Zurbuchen, T. H.; Benna, M.; Mahaffy, P. R.
2011-12-15
This paper describes a technique to significantly improve upon the mass peak shape and mass resolution of spaceborne quadrupole mass spectrometers (QMSs) through higher order auxiliary excitation of the quadrupole field. Using a novel multiresonant tank circuit, additional frequency components can be used to drive modulating voltages on the quadrupole rods in a practical manner, suitable for both improved commercial applications and spaceflight instruments. Auxiliary excitation at frequencies near twice that of the fundamental quadrupole RF frequency provides the advantages of previously studied parametric excitation techniques, but with the added benefit of increased sensed excitation amplitude dynamic range and the ability to operate voltage scan lines through the center of upper stability islands. Using a field programmable gate array, the amplitudes and frequencies of all QMS signals are digitally generated and managed, providing a robust and stable voltage control system. These techniques are experimentally verified through an interface with a commercial Pfeiffer QMG422 quadrupole rod system. When operating through the center of a stability island formed from higher order auxiliary excitation, approximately 50% and 400% improvements in 1% mass resolution and peak stability were measured, respectively, when compared with traditional QMS operation. Although tested with a circular rod system, the presented techniques have the potential to improve the performance of both circular and hyperbolic rod geometry QMS sensors.
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 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.
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
A Recurrence Relation Approach to Higher Order Quantum Superintegrability
NASA Astrophysics Data System (ADS)
Kalnins, Ernie G.; Kress, Jonathan M.; Miller, Willard
2011-03-01
We develop our method to prove quantum superintegrability of an integrable 2D system, based on recurrence relations obeyed by the eigenfunctions of the system with respect to separable coordinates. We show that the method provides rigorous proofs of superintegrability and explicit constructions of higher order generators for the symmetry algebra. We apply the method to 5 families of systems, each depending on a parameter k, including most notably the caged anisotropic oscillator, the Tremblay, Turbiner and Winternitz system and a deformed Kepler-Coulomb system, and we give proofs of quantum superintegrability for all rational values of k, new for 4 of these systems. In addition, we show that the explicit information supplied by the special function recurrence relations allows us to prove, for the first time in 4 cases, that the symmetry algebra generated by our lowest order symmetries closes and to determine the associated structure equations of the algebras for each k. We have no proof that our generating symmetries are of lowest possible order, but we have no counterexamples, and we are confident we can can always find any missing generators from our raising and lowering operator recurrences. We also get for free, one variable models of the action of the symmetry algebra in terms of difference operators. We describe how the Stäckel transform acts and show that it preserves the structure equations.
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
Novel Object Exploration as a Potential Assay for Higher Order Repetitive Behaviors in Mice.
Steinbach, Jessica M; Garza, Elizabeth T; Ryan, Bryce C
2016-01-01
Restricted, repetitive behaviors (RRBs) are a core feature of autism spectrum disorder (ASD) and disrupt the lives of affected individuals. RRBs are commonly split into lower-order and higher-order components, with lower order RRBs consisting of motor stereotypies and higher order RRBs consisting of perseverative and sequencing behaviors. Higher order RRBs are challenging to model in mice. Current assays for RRBs in mice focus primarily on the lower order components, making basic biomedical research into potential treatments or interventions for higher-order RRBs difficult. Here we describe a new assay, novel object exploration. This assay uses a basic open-field arena with four novel objects placed around the perimeter. The test mouse is allowed to freely explore the arena and the order in which the mouse investigates the novel objects is recorded. From these data, patterned sequences of exploration can be identified, as can the most preferred object for each mouse. The representative data shared here and past results using the novel object exploration assay illustrate that inbred mouse strains do demonstrate different behavior in this assay and that strains with elevated lower order RRBs also show elevated patterned behavior. As such, the novel object exploration assay appears to possess good face validity for higher order RRBs in humans and may be a valuable assay for future studies investigating novel therapeutics for ASD. PMID:27583676
Higher Order Aberration and Astigmatism in Children with Hyperopic Amblyopia
Choi, Seung Kwon
2016-01-01
Purpose To investigate the changes in corneal higher-order aberration (HOA) during amblyopia treatment and the correlation between HOA and astigmatism in hyperopic amblyopia children. Methods In this retrospective study, a total of 72 eyes from 72 patients ranging in age from 38 to 161 months were included. Patients were divided into two groups based on the degree of astigmatism. Corneal HOA was measured using a KR-1W aberrometer at the initial visit and at 3-, 6-, and 12-month follow-ups. Correlation analysis was performed to assess the association between HOA and astigmatism. Results A total of 72 patients were enrolled in this study, 37 of which were classified as belonging to the higher astigmatism group, while 35 were assigned to the lower astigmatism group. There was a statistically significant difference in success rate between the higher and lower astigmatism groups. In both groups, all corneal HOAs were significantly reduced during amblyopia treatment. When comparing the two groups, a significant difference in coma HOA at the 12-month follow-up was detected (p = 0.043). In the Pearson correlation test, coma HOA at the 12-month follow-up demonstrated a statistically significant correlation with astigmatism and a stronger correlation with astigmatism in the higher astigmatism group than in the lower astigmatism group (coefficient values, 0.383 and 0.284 as well as p = 0.021 and p = 0.038, respectively). Conclusions HOA, particularly coma HOA, correlated with astigmatism and could exert effects in cases involving hyperopic amblyopia. PMID:26865804
Polarization and visibility of higher-order rainbows.
Können, Gunther P
2015-02-01
The degree of polarization of rainbows of order k with k≥3 is bounded in the interval [75%, 78%], where 75% is the limit for k→∞. A polarization filter can improve the signal-to-background ratio of the third and fourth rainbows by a factor of 2, which may lift their visibilities in natural circumstances above the threshold of human visual perception. Under optimal circumstances, the latter may be true for the recently photographed green fingerprint of the fifth rainbow, even without the aid of a polarization filter. The prospects for observing the sixth rainbow are unclear. There exists a possibility that the signal of the natural seventh rainbow (appearing at 64° from the Sun) may be separated from its background if photographed under perfect conditions through a polarization filter. PMID:25967836
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.
Steganographic system based on higher-order statistics
NASA Astrophysics Data System (ADS)
Tzschoppe, Roman; Baeuml, Robert; Huber, Johannes; Kaup, Andre
2003-06-01
Universal blind steganalysis attempts to detect steganographic data without knowledge about the applied steganographic system. Farid proposed such a detection algorithm based on higher-order statistics for separating original images from stego images. His method shows an astonishing performance on current steganographic schemes. Starting from the statistical approach in Farid's algorithm, we investigate the well known steganographic tool Jsteg as well as a newer approach proposed by Eggers et al., which relies on histogram-preserving data mapping. Both schemes show weaknesses leading to a certain detectability. Further analysis shows which statistic characteristics make both schemes vulnerable. Based on these results, the histogram preserving approach is enhanced such that it achieves perfect security with respect to Farid's algorithm.
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.
On negative higher-order Kerr effect and filamentation
NASA Astrophysics Data System (ADS)
Loriot, V.; Béjot, P.; Ettoumi, W.; Petit, Y.; Kasparian, J.; Henin, S.; Hertz, E.; Lavorel, B.; Faucher, O.; Wolf, J.-P.
2011-07-01
As a contribution to the ongoing controversy about the role of higher-order Kerr effect (HOKE) in laser filamentation, we first provide thorough details about the protocol that has been employed to infer the HOKE indices from the experiment. Next, we discuss potential sources of artifact in the experimental measurements of these terms and show that neither the value of the observed birefringence, nor its inversion, nor the intensity at which it is observed, appear to be flawed. Furthermore, we argue that, independently on our values, the principle of including HOKE is straightforward. Due to the different temporal and spectral dynamics, the respective efficiency of defocusing by the plasma and by the HOKE is expected to depend substantially on both incident wavelength and pulse duration. The discussion should therefore focus on defining the conditions where each filamentation regime dominates.
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.
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
2016-04-01
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.
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.
Evaluative conditioning depends on higher order encoding processes.
Fiedler, Klaus; Unkelbach, Christian
2011-06-01
Evaluative conditioning (EC) is commonly conceived as stimulus-driven associative learning. Here, we show that internally generated encoding activities mediate EC effects: Neutral conditioned stimuli (CS) faces were paired with positive and negative unconditioned stimuli (US) faces. Depending on the encoding task (Is CS a friend vs. enemy of US?), Experiment 1 yielded either normal EC effects (CS adopting US valence) or a reversal. This pattern was conditional on the degree to which encoding judgements affirmed friend or enemy encoding schemes. Experiments 2a and 2b replicated these findings with more clearly valenced US faces and controlling for demand effects. Experiment 3 demonstrated unconditional encoding effects when participants generated friend or enemy relations between CS and US faces. Explicitly stated friend or enemy relations in Experiment 4 left EC effects unaffected. Together, these findings testify to the importance of higher order cognitive processes in conditioning, much in line with recent evidence on the crucial role of conditioning awareness. PMID:21547766
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.
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.
Revealing Higher Order Protein Structure Using Mass Spectrometry.
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. Graphical Abstract ᅟ. PMID:27080007
Detailed Modeling of Higher Order Hierarchical Kepler Star Systems
NASA Astrophysics Data System (ADS)
Gore, Joanna; Orosz, Jerome A.
2016-06-01
Most stars have stellar companions (i.e. they exist in double, triple, or higher order configurations). Binary star systems are those which contain two stars. These systems are valued scientifically because they allow for the measurement of fundamental stellar properties such as masses and radii. These properties in turn allow for detailed studies of stellar evolution. The Kepler space telescope has discovered roughly 2900 eclipsing binary stars in its field of view. Various studies have shown that roughly 20% of the Kepler eclipsing binaries contain companions are are most likely triple star systems. We present a preliminary survey of the orbital properties of the tertiary bodies in a sample of thirty triple systems. In addition, a small number of the triple systems show eclipse events due to the third star. We present the results of detailed modeling of two of these systems, and discuss how in some cases these triple systems allow for extremely precise measurements of the fundamental stellar parameters.
Higher Order Mode Excitations in Gyro-amplifiers
NASA Astrophysics Data System (ADS)
Nguyen, Khanh
2000-10-01
A key element in the design of gyro-amplifier RF structures is the minimization of unwanted modes. For example, a nonlinear output taper is often employed in the transition from the near cutoff radius of the interacting circuit to a much larger output waveguide, which also serves as the collector. The taper designs are usually done without considering the effect of a bunched beam. However, recent simulations [1] with the self-consistent MAGY code [2] reveal that higher order mode interactions with the bunched electron beam can substantially compromise the mode purity of the RF output. The interaction in the taper region is that of a travelling-wave type and is strongly dependent on the beam bunching characteristics resulting from previous interaction with the operating mode in the interacting circuit. Subsequent to this prediction, an experiment was performed to measure the RF output mode content from a Ka-band gyro-klystron at the Naval Research Laboratory. The agreement between salient theoretical and measured RF output characteristics confirms the existence higher order mode excitation in output tapers as predicted by theory. Another example of the need to employ self-consistent theoretical model in the design of gyro-amplifier RF structures is the phenomenon of beam-induced RF excitation in drift sections, which are cutoff to the operating mode and are used to separate cavities in gyroklystron amplifiers. This non-resonant RF excitation is at the drive frequency and the RF field structure is that of the operating mode. The RF amplitude is found to scale linearly with the bunched beam current. The presence of RF in the drift section has important thermal implications in the design and use of lossy dielectrics in drift-sections, especially for high-average power devices. [1] K. Nguyen, et al., IEEE Trans. Plasma Science, in press 2000. [2] M. Botton, et al., IEEE Trans. Plasma Science, V.26, p.882, June 1998.
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.
Phantom Friedmann cosmologies and higher-order characteristics of expansion
Dabrowski, Mariusz P. . E-mail: mpdabfz@sus.univ.szczecin.pl; Stachowiak, Tomasz . E-mail: toms@oa.uj.edu.pl
2006-04-15
We discuss a more general class of phantom (p < -{rho}) cosmologies with various forms of both phantom (w < -1), and standard (w > -1) matter. We show that many types of evolution which include both Big-Bang and Big-Rip singularities are admitted and give explicit examples. Among some interesting models, there exist non-singular oscillating (or 'bounce') cosmologies, which appear due to a competition between positive and negative pressure of variety of matter content. From the point of view of the current observations the most interesting cosmologies are the ones which start with a Big-Bang and terminate at a Big-Rip. A related consequence of having a possibility of two types of singularities is that there exists an unstable static universe approached by the two asymptotic models-one of them reaches Big-Bang, and another reaches Big-Rip. We also give explicit relations between density parameters {omega} and the dynamical characteristics for these generalized phantom models, including higher-order observational characteristics such as jerk and 'kerk.' Finally, we discuss the observational quantities such as luminosity distance, angular diameter, and source counts, both in series expansion and explicitly, for phantom models. Our series expansion formulas for the luminosity distance and the apparent magnitude go as far as to the fourth-order in redshift z term, which includes explicitly not only the jerk, but also the 'kerk' (or 'snap') which may serve as an indicator of the curvature of the universe.
Higher-order spike triggered analysis of neural oscillators.
Ota, Keisuke; Omori, Toshiaki; Miyakawa, Hiroyoshi; Okada, Masato; Aonishi, Toru
2012-01-01
For the purpose of elucidating the neural coding process based on the neural excitability mechanism, researchers have recently investigated the relationship between neural dynamics and the spike triggered stimulus ensemble (STE). Ermentrout et al. analytically derived the relational equation between the phase response curve (PRC) and the spike triggered average (STA). The STA is the first cumulant of the STE. However, in order to understand the neural function as the encoder more explicitly, it is necessary to elucidate the relationship between the PRC and higher-order cumulants of the STE. In this paper, we give a general formulation to relate the PRC and the nth moment of the STE. By using this formulation, we derive a relational equation between the PRC and the spike triggered covariance (STC), which is the covariance of the STE. We show the effectiveness of the relational equation through numerical simulations and use the equation to identify the feature space of the rat hippocampal CA1 pyramidal neurons from their PRCs. Our result suggests that the hippocampal CA1 pyramidal neurons oscillating in the theta frequency range are commonly sensitive to inputs composed of theta and gamma frequency components. PMID:23226249
SPHS: smoothed particle hydrodynamics with a higher order dissipation switch
NASA Astrophysics Data System (ADS)
Read, J. I.; Hayfield, T.
2012-06-01
We present a novel implementation of smoothed particle hydrodynamics that uses the spatial derivative of the velocity divergence as a higher order dissipation switch. Our switch - which is second order accurate - detects flow convergence before it occurs. If particle trajectories are going to cross, we switch on the usual SPH artificial viscosity, as well as conservative dissipation in all advected fluid quantities (e.g. the entropy). The viscosity and dissipation terms (that are numerical errors) are designed to ensure that all fluid quantities remain single valued as particles approach one another, to respect conservation laws, and to vanish on a given physical scale as the resolution is increased. SPHS alleviates a number of known problems with 'classic' SPH, successfully resolving mixing, and recovering numerical convergence with increasing resolution. An additional key advantage is that - treating the particle mass similarly to the entropy - we are able to use multimass particles, giving significantly improved control over the refinement strategy. We present a wide range of code tests including the Sod shock tube, Sedov-Taylor blast wave, Kelvin-Helmholtz Instability, the 'blob test' and some convergence tests. Our method performs well on all tests, giving good agreement with analytic expectations.
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.
The effect of higher order harmonics on second order nonlinear phenomena
NASA Astrophysics Data System (ADS)
Shahverdi, Amin; Borji, Amir
2015-05-01
A new method which is a combination of the harmonic balance and finite difference techniques (HBFD) is proposed for complete time-harmonic solution of the nonlinear wave equation. All interactions between different harmonics up to an arbitrary order can be incorporated. The effect of higher order harmonics on two important nonlinear optical phenomena, namely, the second harmonic generation (SHG) and frequency mixing is investigated by this method and the results are compared with well-known analytical solutions. The method is quite general and can be used to study wave propagation in all nonlinear media.
Higher-order Fourier analysis over finite fields and applications
NASA Astrophysics Data System (ADS)
Hatami, Pooya
Higher-order Fourier analysis is a powerful tool in the study of problems in additive and extremal combinatorics, for instance the study of arithmetic progressions in primes, where the traditional Fourier analysis comes short. In recent years, higher-order Fourier analysis has found multiple applications in computer science in fields such as property testing and coding theory. In this thesis, we develop new tools within this theory with several new applications such as a characterization theorem in algebraic property testing. One of our main contributions is a strong near-equidistribution result for regular collections of polynomials. The densities of small linear structures in subsets of Abelian groups can be expressed as certain analytic averages involving linear forms. Higher-order Fourier analysis examines such averages by approximating the indicator function of a subset by a function of bounded number of polynomials. Then, to approximate the average, it suffices to know the joint distribution of the polynomials applied to the linear forms. We prove a near-equidistribution theorem that describes these distributions for the group F(n/p) when p is a fixed prime. This fundamental fact was previously known only under various extra assumptions about the linear forms or the field size. We use this near-equidistribution theorem to settle a conjecture of Gowers and Wolf on the true complexity of systems of linear forms. Our next application is towards a characterization of testable algebraic properties. We prove that every locally characterized affine-invariant property of functions f : F(n/p) → R with n∈ N, is testable. In fact, we prove that any such property P is proximity-obliviously testable. More generally, we show that any affine-invariant property that is closed under subspace restrictions and has "bounded complexity" is testable. We also prove that any property that can be described as the property of decomposing into a known structure of low
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…
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.
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
Spectral imaging to visualize higher-order genomic organization.
Sawyer, Iain A; Shevtsov, Sergei P; Dundr, Miroslav
2016-05-01
A concern in the field of genomics is the proper interpretation of large, high-throughput sequencing datasets. The use of DNA FISH followed by high-content microscopy is a valuable tool for validation and contextualization of frequently occurring gene pairing events at the single-cell level identified by deep sequencing. However, these techniques possess certain limitations. Firstly, they do not permit the study of colocalization of many gene loci simultaneously. Secondly, the direct assessment of the relative position of many clustered gene loci within their respective chromosome territories is impossible. Thus, methods are required to advance the study of higher-order nuclear and cellular organization. Here, we describe a multiplexed DNA FISH technique combined with indirect immunofluorescence to study the relative position of 6 distinct genomic or cellular structures. This can be achieved in a single hybridization step using spectral imaging during image acquisition and linear unmixing. Here, we detail the use of this method to quantify gene pairing between highly expressed spliceosomal genes and compare these data to randomly positioned in silico simulated gene clusters. This is a potentially universally applicable approach for the validation of 3C-based technologies, deep imaging of spatial organization within the nucleus and global cellular organization. PMID:27167405
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.
Higher-Order Synaptic Interactions Coordinate Dynamics in Recurrent Networks.
Chambers, Brendan; MacLean, Jason N
2016-08-01
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
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 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.
Invariants of velocities and higher-order Grassmann bundles
NASA Astrophysics Data System (ADS)
Grigore, Dan Radu; Krupka, Demeter
1998-02-01
An ( r, n)-velocity is an r-jet with source at 0 ɛ Rn, and target in a manifold Y. An ( r, n)-velocity is said to be regular if it has a representative which is an immersion at 0 ɛ Rn. The manifold TnrY of ( r, n)-velocities as well as its open, Lnr-invariant, dense submanifold Imm TnrY of regular ( r, n)-velocities, are endowed with a natural action of the differential group Lnr of invertible r-jets with source and target 0 ɛ Rn. In this paper, we describe all continuous, Lnr-invariant, real-valued functions on TnrY and Imm TnrY. We find local bases of Lnr-invariants Imm TnrY in an explicit, recurrent form. To this purpose, higher-order Grassmann bundles are considered as the corresponding quotients P nrY = Imm{T nrY }/{L nr}, and their basic properties are studied. We show that nontrivial Lnr-invariants on Imm TnrY cannot be continuously extended onto TnrY.
Transcriptional Derepression Uncovers Cryptic Higher-Order Genetic Interactions
Taylor, Matthew B.; Ehrenreich, Ian M.
2015-01-01
Disruption of certain genes can reveal cryptic genetic variants that do not typically show phenotypic effects. Because this phenomenon, which is referred to as ‘phenotypic capacitance’, is a potential source of trait variation and disease risk, it is important to understand how it arises at the genetic and molecular levels. Here, we use a cryptic colony morphology trait that segregates in a yeast cross to explore the mechanisms underlying phenotypic capacitance. We find that the colony trait is expressed when a mutation in IRA2, a negative regulator of the Ras pathway, co-occurs with specific combinations of cryptic variants in six genes. Four of these genes encode transcription factors that act downstream of the Ras pathway, indicating that the phenotype involves genetically complex changes in the transcriptional regulation of Ras targets. We provide evidence that the IRA2 mutation reveals the phenotypic effects of the cryptic variants by disrupting the transcriptional silencing of one or more genes that contribute to the trait. Supporting this role for the IRA2 mutation, deletion of SFL1, a repressor that acts downstream of the Ras pathway, also reveals the phenotype, largely due to the same cryptic variants that were detected in the IRA2 mutant cross. Our results illustrate how higher-order genetic interactions among mutations and cryptic variants can result in phenotypic capacitance in specific genetic backgrounds, and suggests these interactions might reflect genetically complex changes in gene expression that are usually suppressed by negative regulation. PMID:26484664
Image Segmentation Using Higher-Order Correlation Clustering.
Kim, Sungwoong; Yoo, Chang D; Nowozin, Sebastian; Kohli, Pushmeet
2014-09-01
In this paper, a hypergraph-based image segmentation framework is formulated in a supervised manner for many high-level computer vision tasks. To consider short- and long-range dependency among various regions of an image and also to incorporate wider selection of features, a higher-order correlation clustering (HO-CC) is incorporated in the framework. Correlation clustering (CC), which is a graph-partitioning algorithm, was recently shown to be effective in a number of applications such as natural language processing, document clustering, and image segmentation. It derives its partitioning result from a pairwise graph by optimizing a global objective function such that it simultaneously maximizes both intra-cluster similarity and inter-cluster dissimilarity. In the HO-CC, the pairwise graph which is used in the CC is generalized to a hypergraph which can alleviate local boundary ambiguities that can occur in the CC. Fast inference is possible by linear programming relaxation, and effective parameter learning by structured support vector machine is also possible by incorporating a decomposable structured loss function. Experimental results on various data sets show that the proposed HO-CC outperforms other state-of-the-art image segmentation algorithms. The HO-CC framework is therefore an efficient and flexible image segmentation framework. PMID:26352230
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.
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 finite element analysis of thick composite laminates
NASA Technical Reports Server (NTRS)
Goering, J.; Kim, H. J.
1992-01-01
A higher order, sub-parametric, laminated, 3D solid finite element was used for the analysis of very thick laminated composite plates. The geometry of this element is defined by four nodes in the X-Y plane which define a prism of material through the thickness of the laminate. There are twenty-four degrees of freedom at each node; translations at the upper and lower surfaces of the laminate in each of the three coordinate directions, and the derivatives of these translations with respect to each coordinate. This choice of degrees of freedom leads to displacement and strain compatibility at the corners. Stacking sequence effects are accounted for by explicitly integrating the strain energy density through the thickness of the element. The laminated solid element was combined with a gap-contact element to analyze thick laminated composite lugs loaded through flexible pins. The resulting model accounts for pin bending effects that produce non-uniform bearing stresses through the thickness of the lug. A thick composite lug experimental test program was performed, and provided data that was used to validate the analytical model. Two lug geometries and three stacking sequences were tested.
Higher order structure of proteins solubilized in AOT reverse micelles.
Naoe, Kazumitsu; Noda, Kazuki; Kawagoe, Mikio; Imai, Masanao
2004-11-15
The higher order structure of proteins solubilized in an bis(2-ethylhexyl) sulfosuccinate sodium (AOT) reverse micellar system was investigated. From circular dichroic (CD) measurement, CD spectra of cytochrome c, which is solubilized at the interface of reverse micelles, markedly changed on going from buffer solution to the reverse micellar solution, and the ellipticity values in the far- and near-UV regions decreased with decreasing the water content (W0: molar ratio of water to AOT), indicating that the secondary and tertiary structures of cytochrome c changed with the water content. The ellipticity of ribonuclease A, which is solubilized in the center of micellar water pool, in the near-UV region was dependent on W0 and became minimum when W0 of ca. 8 while the ellipticity in the far-UV region was almost constant, indicating that the tertiary structure of ribonuclease A was affected by the water content, but the secondary structure was conserved. The degree of curvature of the micellar interface appears to influence the protein structure because the reverse micelle size is linearly proportional to the W0 value. As evidence of this, when the micelle size was comparable to the protein's dimensions, the structures were more affected by the water content. Judging from the dependence of the factor influencing the protein structure on the protein species, the location of solubilized protein in reverse micelles is significantly related to whether the protein structure in the system is affected by the micellar interface. In the cases of cytochrome c and lysozyme, the ellipticity against W0 was dependent on the AOT concentration. In contrast, ribonuclease A gave very similar ellipticity values whatever the AOT concentration. In the n-hexane micellar system, cytochrome c exhibited lower ellipticity values and ribonuclease A in the lower W0 range (W0
Higher-order renormalization of graphene many-body theory
NASA Astrophysics Data System (ADS)
González, J.
2012-08-01
We study the many-body theory of graphene Dirac quasiparticles interacting via the long-range Coulomb potential, taking as a starting point the ladder approximation to different vertex functions. We test in this way the low-energy behavior of the electron system beyond the simple logarithmic dependence of electronic correlators on the high-energy cutoff, which is characteristic of the large- N approximation. We show that the graphene many-body theory is perfectly renormalizable in the ladder approximation, as all higher powers in the cutoff dependence can be absorbed into the redefinition of a finite number of parameters (namely, the Fermi velocity and the weight of the fields) that remain free of infrared divergences even at the charge neutrality point. We illustrate this fact in the case of the vertex for the current density, where a complete cancellation between the cutoff dependences of vertex and electron self-energy corrections becomes crucial for the preservation of the gauge invariance of the theory. The other potentially divergent vertex corresponds to the staggered (sublattice odd) charge density, which is made cutoff independent by a redefinition in the scale of the density operator. This allows to compute a well-defined, scale invariant anomalous dimension to all orders in the ladder series, which becomes singular at a value of the interaction strength marking the onset of chiral symmetry breaking (and gap opening) in the Dirac field theory. The critical coupling we obtain in this way matches with great accuracy the value found with a quite different method, based on the resolution of the gap equation, thus reassuring the predictability of our renormalization approach.
Divergence of Mammalian Higher Order Chromatin Structure Is Associated with Developmental Loci
Chambers, Emily V.; Bickmore, Wendy A.; Semple, Colin A.
2013-01-01
Several recent studies have examined different aspects of mammalian higher order chromatin structure – replication timing, lamina association and Hi-C inter-locus interactions — and have suggested that most of these features of genome organisation are conserved over evolution. However, the extent of evolutionary divergence in higher order structure has not been rigorously measured across the mammalian genome, and until now little has been known about the characteristics of any divergent loci present. Here, we generate a dataset combining multiple measurements of chromatin structure and organisation over many embryonic cell types for both human and mouse that, for the first time, allows a comprehensive assessment of the extent of structural divergence between mammalian genomes. Comparison of orthologous regions confirms that all measurable facets of higher order structure are conserved between human and mouse, across the vast majority of the detectably orthologous genome. This broad similarity is observed in spite of many loci possessing cell type specific structures. However, we also identify hundreds of regions (from 100 Kb to 2.7 Mb in size) showing consistent evidence of divergence between these species, constituting at least 10% of the orthologous mammalian genome and encompassing many hundreds of human and mouse genes. These regions show unusual shifts in human GC content, are unevenly distributed across both genomes, and are enriched in human subtelomeric regions. Divergent regions are also relatively enriched for genes showing divergent expression patterns between human and mouse ES cells, implying these regions cause divergent regulation. Particular divergent loci are strikingly enriched in genes implicated in vertebrate development, suggesting important roles for structural divergence in the evolution of mammalian developmental programmes. These data suggest that, though relatively rare in the mammalian genome, divergence in higher order chromatin
Dynamics and phenomenology of higher order gravity cosmological models
NASA Astrophysics Data System (ADS)
Moldenhauer, Jacob Andrew
2010-10-01
I present here some new results about a systematic approach to higher-order gravity (HOG) cosmological models. The HOG models are derived from curvature invariants that are more general than the Einstein-Hilbert action. Some of the models exhibit late-time cosmic acceleration without the need for dark energy and fit some current observations. The open question is that there are an infinite number of invariants that one could select, and many of the published papers have stressed the need to find a systematic approach that will allow one to study methodically the various possibilities. We explore a new connection that we made between theorems from the theory of invariants in general relativity and these cosmological models. In summary, the theorems demonstrate that curvature invariants are not all independent from each other and that for a given Ricci Segre type and Petrov type (symmetry classification) of the space-time, there exists a complete minimal set of independent invariants (a basis) in terms of which all the other invariants can be expressed. As an immediate consequence of the proposed approach, the number of invariants to consider is dramatically reduced from infinity to four invariants in the worst case and to only two invariants in the cases of interest, including all Friedmann-Lemaitre-Robertson-Walker metrics. We derive models that pass stability and physical acceptability conditions. We derive dynamical equations and phase portrait analyses that show the promise of the systematic approach. We consider observational constraints from magnitude-redshift Supernovae Type Ia data, distance to the last scattering surface of the Cosmic Microwave Background radiation, and Baryon Acoustic Oscillations. We put observational constraints on general HOG models. We constrain different forms of the Gauss-Bonnet, f(G), modified gravity models with these observations. We show some of these models pass solar system tests. We seek to find models that pass physical and
Construction of higher order accurate vortex and particle methods
NASA Technical Reports Server (NTRS)
Nicolaides, R. A.
1986-01-01
The standard point vortex method has recently been shown to be of high order of accuracy for problems on the whole plane, when using a uniform initial subdivision for assigning the vorticity to the points. If obstacles are present in the flow, this high order deteriorates to first or second order. New vortex methods are introduced which are of arbitrary accuracy (under regularity assumptions) regardless of the presence of bodies and the uniformity of the initial subdivision.
Correcting vortex splitting in higher order vortex beams.
Neo, Richard; Tan, Shiaw Juen; Zambrana-Puyalto, Xavier; Leon-Saval, Sergio; Bland-Hawthorn, Joss; Molina-Terriza, Gabriel
2014-04-21
We demonstrate a general method for the first order compensation of singularity splitting in a vortex beam at a single plane. By superimposing multiple forked holograms on the SLM used to generate the vortex beam, we are able to compensate vortex splitting and generate beams with desired phase singularities of order ℓ = 0, 1, 2, and 3 in one plane. We then extend this method by application of a radial phase, in order to simultaneously compensate the observed vortex splitting at two planes (near and far field) for an ℓ = 2 beam. PMID:24787874
Higher-order diagrammatic vibrational coupled-cluster theory
NASA Astrophysics Data System (ADS)
Faucheaux, Jacob A.; Hirata, So
2015-10-01
Diagrammatically size-consistent and basis-set-free vibrational coupled-cluster (XVCC) theory for both zero-point energies and transition frequencies of a molecule, the latter through the equation-of-motion (EOM) formalism, is defined for an nth-order Taylor-series potential energy surface (PES). Quantum-field-theoretical tools (the rules of normal-ordered second quantization and Feynman-Goldstone diagrams) for deriving their working equations are established. The equations of XVCC and EOM-XVCC including up to the mth-order excitation operators are derived and implemented with the aid of computer algebra in the range of 1 ≤ m ≤ 8. Algorithm optimizations known as strength reduction, intermediate reuse, and factorization are carried out before code generation, reducing the cost scaling of the mth-order XVCC and EOM-XVCC in an nth-order Taylor-series PES (m ≥ n) to the optimal value of O(Nm+⌊n/2⌋), where N is the number of modes. The calculated zero-point energies and frequencies of fundamentals, overtones, and combinations as well as Fermi-resonant modes display rapid and nearly monotonic convergence with m towards the exact values for the PES. The theory with the same excitation rank as the truncation order of the Taylor-series PES (m = n) seems to strike the best cost-accuracy balance, achieving the accuracy of a few tenths of cm-1 for transitions involving (m - 3) modes and of a few cm-1 for those involving (m - 2) modes. The relationships between XVCC and the vibrational coupled-cluster theories of Prasad and coworkers and of Christiansen and coworkers as well as the size-extensive vibrational self-consistent-field and many-body perturbation theories are also elucidated.
Higher-order diagrammatic vibrational coupled-cluster theory.
Faucheaux, Jacob A; Hirata, So
2015-10-01
Diagrammatically size-consistent and basis-set-free vibrational coupled-cluster (XVCC) theory for both zero-point energies and transition frequencies of a molecule, the latter through the equation-of-motion (EOM) formalism, is defined for an nth-order Taylor-series potential energy surface (PES). Quantum-field-theoretical tools (the rules of normal-ordered second quantization and Feynman-Goldstone diagrams) for deriving their working equations are established. The equations of XVCC and EOM-XVCC including up to the mth-order excitation operators are derived and implemented with the aid of computer algebra in the range of 1 ≤ m ≤ 8. Algorithm optimizations known as strength reduction, intermediate reuse, and factorization are carried out before code generation, reducing the cost scaling of the mth-order XVCC and EOM-XVCC in an nth-order Taylor-series PES (m ≥ n) to the optimal value of O(N(m+⌊n/2⌋)), where N is the number of modes. The calculated zero-point energies and frequencies of fundamentals, overtones, and combinations as well as Fermi-resonant modes display rapid and nearly monotonic convergence with m towards the exact values for the PES. The theory with the same excitation rank as the truncation order of the Taylor-series PES (m = n) seems to strike the best cost-accuracy balance, achieving the accuracy of a few tenths of cm(-1) for transitions involving (m - 3) modes and of a few cm(-1) for those involving (m - 2) modes. The relationships between XVCC and the vibrational coupled-cluster theories of Prasad and coworkers and of Christiansen and coworkers as well as the size-extensive vibrational self-consistent-field and many-body perturbation theories are also elucidated. PMID:26450290
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…
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…
Higher-Order Semi-Implicit Projection Methods
Minion, M L
2001-09-06
A semi-implicit form of the method of spectral deferred corrections is applied to the solution of the incompressible Navier-Stokes equations. A methodology for constructing semi-implicit projection methods with arbitrarily high order of temporal accuracy in both the velocity and pressure is presented. Three variations of projection methods are discussed which differ in the manner in which the auxiliary velocity and the pressure are calculated. The presentation will make clear that project methods in general need not be viewed as fractional step methods as is often the practice. Two simple numerical examples re used to demonstrate fourth-order accuracy in time for an implementation of each variation of projection method.
Higher order chromatin structure: bridging physics and biology
Fudenberg, Geoffrey; Mirny, Leonid A.
2012-01-01
Recent advances in microscopy and genomic techniques have provided new insight into spatial chromatin organization inside of the nucleus. In particular, chromosome conformation capture data has highlighted the relevance of polymer physics for high-order chromatin organization. In this context, we review basic polymer states, discuss how an appropriate polymer model can be determined from experimental data, and examine the success and limitations of various polymer models of high-order interphase chromatin organization. By taking into account topological constraints acting on the chromatin fiber, recently-developed polymer models of interphase chromatin can reproduce the observed scaling of distances between genomic loci, chromosomal territories, and probabilities of contacts between loci measured by chromosome conformation capture methods. Polymer models provide a framework for the interpretation of experimental data as ensembles of conformations rather than collections of loops, and will be crucial for untangling functional implications of chromosomal organization. PMID:22360992
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.
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.
Wavelet steerability and the higher-order Riesz transform.
Unser, Michael; Van De Ville, Dimitri
2010-03-01
Our main goal in this paper is to set the foundations of a general continuous-domain framework for designing steerable, reversible signal transformations (a.k.a. frames) in multiple dimensions ( d >or= 2). To that end, we introduce a self-reversible, Nth-order extension of the Riesz transform. We prove that this generalized transform has the following remarkable properties: shift-invariance, scale-invariance, inner-product preservation, and steerability. The pleasing consequence is that the transform maps any primary wavelet frame (or basis) of [Formula: see text] into another "steerable" wavelet frame, while preserving the frame bounds. The concept provides a functional counterpart to Simoncelli's steerable pyramid whose construction was primarily based on filterbank design. The proposed mechanism allows for the specification of wavelets with any order of steerability in any number of dimensions; it also yields a perfect reconstruction filterbank algorithm. We illustrate the method with the design of a novel family of multidimensional Riesz-Laplace wavelets that essentially behave like the N th-order partial derivatives of an isotropic Gaussian kernel. PMID:20031498
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.
Higher-order Boltzmann machines and entropy bounds
NASA Astrophysics Data System (ADS)
Apolloni, Bruno; Battistini, Egidio; de Falco, Diego
1999-07-01
We examine some aspects of the interface area between mathematical statistics and statistical physics relevant to the study of Boltzmann machines. The Boltzmann machine learning algorithm is based on a variational principle (Gibbs' lemma for relative entropy). This fact suggests the possibility of a scheme of successive approximations: here we consider successive approximations parametrized by the order of many-body interactions among individual units. We prove bounds on the gain in relative entropy in the crucial step of adding, and estimating by Hebb's rule, a new parameter. We address the problem of providing, on the basis of local observations, upper and lower bounds on the entropy. While upper bounds are easily obtained by subadditivity, lower bounds involve localization of Hirschman bounds on a dual quantum system.
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.
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 higher order structure and treats items independently from one another. We present a probabilistic model of change detection that attempts to bridge this gap by formalizing the role of perceptual organization and allowing for richer, more structured memory representations. Using either standard visual working memory displays or displays in which the items are purposefully arranged in patterns, we find that models that take into account perceptual grouping between items and the encoding of higher order summary information are necessary to account for human change detection performance. Considering the higher order structure of items in visual working memory will be critical for models to make useful predictions about observers' memory capacity and change detection abilities in simple displays as well as in more natural scenes. PMID:23230888
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
Superintegrability and higher order integrals for quantum systems
NASA Astrophysics Data System (ADS)
Kalnins, E. G.; Kress, J. M.; Miller, W., Jr.
2010-07-01
We refine a method for finding a canonical form of symmetry operators of arbitrary order for the Schrödinger eigenvalue equation HΨ ≡ (Δ2 + V)Ψ = EΨ on any 2D Riemannian manifold, real or complex, that admits a separation of variables in some orthogonal coordinate system. The flat space equations with potentials V = α(x + iy)k - 1/(x - iy)k + 1 in Cartesian coordinates, and V = αr2 + β/r2cos 2kθ + γ/r2sin 2kθ (the Tremblay, Turbiner and Winternitz system) in polar coordinates, have each been shown to be classically superintegrable for all rational numbers k. We apply the canonical operator method to give a constructive proof that each of these systems is also quantum superintegrable for all rational k. We develop the classical analog of the quantum canonical form for a symmetry. It is clear that our methods will generalize to other Hamiltonian systems.
Binary higher order neural networks for realizing Boolean functions.
Zhang, Chao; Yang, Jie; Wu, Wei
2011-05-01
In order to more efficiently realize Boolean functions by using neural networks, we propose a binary product-unit neural network (BPUNN) and a binary π-ς neural network (BPSNN). The network weights can be determined by one-step training. It is shown that the addition " σ," the multiplication " π," and two kinds of special weighting operations in BPUNN and BPSNN can implement the logical operators " ∨," " ∧," and " ¬" on Boolean algebra 〈Z(2),∨,∧,¬,0,1〉 (Z(2)={0,1}), respectively. The proposed two neural networks enjoy the following advantages over the existing networks: 1) for a complete truth table of N variables with both truth and false assignments, the corresponding Boolean function can be realized by accordingly choosing a BPUNN or a BPSNN such that at most 2(N-1) hidden nodes are needed, while O(2(N)), precisely 2(N) or at most 2(N), hidden nodes are needed by existing networks; 2) a new network BPUPS based on a collaboration of BPUNN and BPSNN can be defined to deal with incomplete truth tables, while the existing networks can only deal with complete truth tables; and 3) the values of the weights are all simply -1 or 1, while the weights of all the existing networks are real numbers. Supporting numerical experiments are provided as well. Finally, we present the risk bounds of BPUNN, BPSNN, and BPUPS, and then analyze their probably approximately correct learnability. PMID:21427020
Higher order Peregrine breathers solutions to the NLS equation
NASA Astrophysics Data System (ADS)
Gaillard, Pierre
2015-09-01
The solutions to the one dimensional focusing nonlinear Schrodinger equation (NLS) can be written as a product of an exponential depending on t by a quotient of two polynomials of degree N(N + 1) in x and t. These solutions depend on 2N - 2 parameters : when all these parameters are equal to 0, we obtain the famous Peregrine breathers which we call PN breathers. Between all quasi-rational solutions of rank N fixed by the condition that its absolute value tends to 1 at infinity and its highest maximum is located at point (x = 0,t = 0), the PN breather is distinguished by the fact that PN (0, 0) = 2N + 1. We construct Peregrine breathers of the rank N explicitly for N ≤ 11. We give figures of these PN breathers in the (x; t) plane; plots of the solutions PN (0; t), PN (x;0), never given for 6 < N < 11 are constructed in this work. It is the first time that the Peregrine breather of order 11 is explicitly constructed.
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…
MJO structure associated with the higher-order CEOF modes
NASA Astrophysics Data System (ADS)
Liu, Ping
2014-10-01
the total 432 CEOF modes retain all variance of the baseline MJO, while those higher than 10 contain less information and more noise and can be discarded. Furthermore, this study indicated that the longitudinal STD of the reconstructed anomalies detects the MJO phases and magnitudes in the western Pacific with more physical meaning and in better agreement with the Hovmöller diagrams than the RMM-like amplitude. The results provide an integral figure of the MJO structure from the CEOF analysis and a more robust RMM framework for monitoring the MJO's evolution in real time and for validating its numerical forecast and simulations.
Higher-order multipole amplitudes in charmonium radiative transitions
NASA Astrophysics Data System (ADS)
Artuso, M.; Blusk, S.; Khalil, S.; Mountain, R.; Randrianarivony, K.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Zhang, L. M.; Bonvicini, G.; Cinabro, D.; Lincoln, A.; Smith, M. J.; Zhou, P.; Zhu, J.; Naik, P.; Rademacker, J.; Asner, D. M.; Edwards, K. W.; Reed, J.; Robichaud, A. N.; Tatishvili, G.; White, E. J.; Briere, R. A.; Vogel, H.; Onyisi, P. U. E.; Rosner, J. L.; Alexander, J. P.; Cassel, D. G.; Ehrlich, R.; Fields, L.; Galik, R. S.; Gibbons, L.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hunt, J. M.; Kreinick, D. L.; Kuznetsov, V. E.; Ledoux, J.; Mahlke-Krüger, H.; Patterson, J. R.; Peterson, D.; Riley, D.; Ryd, A.; Sadoff, A. J.; Shi, X.; Stroiney, S.; Sun, W. M.; Yelton, J.; Rubin, P.; Lowrey, N.; Mehrabyan, S.; Selen, M.; Wiss, J.; Kornicer, M.; Mitchell, R. E.; Shepherd, M. R.; Tarbert, C. M.; Besson, D.; Pedlar, T. K.; Xavier, J.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Poling, R.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tan, B. J. Y.; Tomaradze, A.; Brisbane, S.; Libby, J.; Martin, L.; Powell, A.; Spradlin, P.; Thomas, C.; Wilkinson, G.; Mendez, H.; Ge, J. Y.; Miller, D. H.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Hu, D.; Moziak, B.; Napolitano, J.; Ecklund, K. M.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.
2009-12-01
Using 24×106 ψ'≡ψ(2S) decays in CLEO-c, we have searched for higher multipole admixtures in electric-dipole-dominated radiative transitions in charmonia. We find good agreement between our data and theoretical predictions for magnetic quadrupole (M2) amplitudes in the transitions ψ'→γχc1,c2 and χc1,c2→γJ/ψ, in striking contrast to some previous measurements. Let b2J and a2J denote the normalized M2 amplitudes in the respective aforementioned decays, where the superscript J refers to the angular momentum of the χcJ. By performing unbinned maximum likelihood fits to full five-parameter angular distributions, we found the following values of M2 admixtures for Jχ=1: a2J=1=(-6.26±0.63±0.24)×10-2 and b2J=1=(2.76±0.73±0.23)×10-2, which agree well with theoretical expectations for a vanishing anomalous magnetic moment of the charm quark. For Jχ=2, if we fix the electric octupole (E3) amplitudes to zero as theory predicts for transitions between charmonium S states and P states, we find a2J=2=(-9.3±1.6±0.3)×10-2 and b2J=2=(1.0±1.3±0.3)×10-2. If we allow for E3 amplitudes we find, with a four-parameter fit, a2J=2=(-7.9±1.9±0.3)×10-2, b2J=2=(0.2±1.4±0.4)×10-2, a3J=2=(1.7±1.4±0.3)×10-2, and b3J=2=(-0.8±1.2±0.2)×10-2. We determine the ratios a2J=1/a2J=2=0.67-0.13+0.19 and a2J=1/b2J=1=-2.27-0.99+0.57, where the theoretical predictions are independent of the charmed quark magnetic moment and are a2J=1/a2J=2=0.676±0.071 and a2J=1/b2J=1=-2.27±0.16.
Landscape of Higher Education: Human Capital
ERIC Educational Resources Information Center
Edwards, Kelcey; Perfetto, Greg; Hossler, Don; Kelly, Patrick J.
2012-01-01
There are many changes occurring in higher education, and often it is difficult to see trends nationally. In this presentation, experts working with national data present trends in higher education from a forward-looking perspective. Senior researchers from the College Board provide trends using College Board SAT and AP data, as well as new…
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.
NASA Astrophysics Data System (ADS)
Ganapathy, R.; Kuriakose, V. C.
2002-04-01
We obtain conditions for the occurrence of cross-phase modulational instability in the normal dispersion regime for the coupled higher order nonlinear Schrödinger equation with higher order dispersion and nonlinear terms.
Landscape of Higher Education: Human Capital
ERIC Educational Resources Information Center
Edwards, Kelcey; Sawtell, Ellen; Perfetto, Greg; Shapiro, Douglas T.; Kelly, Patrick J.
2013-01-01
In this session presented at the Middle States Regional Forum (February 2013), experts working with national data presented trends in higher education from a forward-looking perspective. Senior researchers from the College Board provided trends using SAT, AP, and Net Price Calculator data. The research director of the National Student…
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. PMID:24319382
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
2016-09-01
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 use of higher-order statistics in rapid object categorization in natural scenes.
Banno, Hayaki; Saiki, Jun
2015-01-01
We can rapidly and efficiently recognize many types of objects embedded in complex scenes. What information supports this object recognition is a fundamental question for understanding our visual processing. We investigated the eccentricity-dependent role of shape and statistical information for ultrarapid object categorization, using the higher-order statistics proposed by Portilla and Simoncelli (2000). Synthesized textures computed by their algorithms have the same higher-order statistics as the originals, while the global shapes were destroyed. We used the synthesized textures to manipulate the availability of shape information separately from the statistics. We hypothesized that shape makes a greater contribution to central vision than to peripheral vision and that statistics show the opposite pattern. Results did not show contributions clearly biased by eccentricity. Statistical information demonstrated a robust contribution not only in peripheral but also in central vision. For shape, the results supported the contribution in both central and peripheral vision. Further experiments revealed some interesting properties of the statistics. They are available for a limited time, attributable to the presence or absence of animals without shape, and predict how easily humans detect animals in original images. Our data suggest that when facing the time constraint of categorical processing, higher-order statistics underlie our significant performance for rapid categorization, irrespective of eccentricity. PMID:25761343
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…
Mauermann, M; Uppenkamp, S; van Hengel, P W; Kollmeier, B
1999-12-01
Critical experiments were performed in order to validate the two-source hypothesis of distortion product otoacoustic emissions (DPOAE) generation. Measurements of the spectral fine structure of DPOAE in response to stimulation with two sinusoids have been performed with normal-hearing subjects. The dependence of fine-structure patterns on the frequency ratio f2/f1 was investigated by changing f1 or f2 only (fixed f2 or fixed f1 paradigm, respectively), and by changing both primaries at a fixed ratio and looking at different order DPOAE. When f2/f1 is varied in the fixed ratio paradigm, the patterns of 2 f1-f2 fine structure vary considerably more if plotted as a function of f2 than as a function of fDP. Different order distortion products located at the same characteristic place on the basilar membrane (BM) show similar patterns for both, the fixed-f2 and fDP paradigms. Fluctuations in DPOAE level up to 20 dB can be observed. In contrast, the results from a fixed-fDP paradigm do not show any fine structure but only an overall dependence of DP level on the frequency ratio, with a maximum for 2f1-f2 at f2/f1 close to 1.2. Similar stimulus configurations used in the experiments have also been used for computer simulations of DPOAE in a nonlinear and active model of the cochlea. Experimental results and model simulations give strong evidence for a two-source model of DPOAE generation: The first source is the initial nonlinear interaction of the primaries close to the f2 place. The second source is caused by coherent reflection from a re-emission site at the characteristic place of the distortion product frequency. The spectral fine structure of DPOAE observed in the ear canal reflects the interaction of both these sources. PMID:10615687
[Second-order retrospective revaluation in human contingency learning].
Numata, Keitaro; Shimazaki, Tsuneo
2009-04-01
We demonstrated second-order retrospective revaluation with three cues (T1, T2, and C) and an outcome, in human contingency learning. Experimental task, PC-controlled video game in which participants were required to observe about the relations between firing missiles and the tank destruction, consisted of three training phases and two rating phases. Groups C+ and C- consisted of same first two training phases, CT+ (cues C and T with an outcome) and T1T2+ followed by C+, or C- training for Groups C+, C-, respectively. In rating phases, it is clearly demonstrated that the judgment of predictive value for the outcome of the T2 were higher by C+ training (second-order unovershadowing) and lowered by C- training (second-order backward blocking). The results for Groups RC+ and RC-, in which the orders of the first two training phase for Groups C+ and C- were interchanged, also showed second-order unovershadowing and second-order backward blocking. These results, the robustness of second-order retrospective revaluation against the order of the first training phases, can be explained by the extended comparator hypothesis and probabilistic contrast model. However, these results cannot be explained by traditional associative learning models. PMID:19489431
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…
Even and Odd Charge Coherent States: Higher-Order Nonclassical Properties and Generation Scheme
NASA Astrophysics Data System (ADS)
Duc, Truong Minh; Dinh, Dang Huu; Dat, Tran Quang
2016-06-01
We examine the higher-order nonclassical properties of the even and odd charge coherent states as well as proposing a scheme to generate these states whose modes can freely travel in open space. We show that the even and odd charge coherent states exhibit both higher-order antibunching and higher-order squeezing. While the two-mode higher-order antibunching occurs in any order and essentially depends on the charge number, the two-mode higher-order squeezing appears only in the even orders. We also prove that these states are genuinely entangled, and they can be generated by means of cross-Kerr media, beam splitters, phase shifts and threshold detectors. We find that the fidelity and the corresponding success probability to generate these states are dependent on the correlative parameters.
Human Rights and Private Ordering in Virtual Worlds
NASA Astrophysics Data System (ADS)
Oosterbaan, Olivier
This paper explores the application of human rights in (persistent) virtual world environments. The paper begins with describing a number of elements that most virtual environments share and that are relevant for the application of human rights in such a setting; and by describing in a general nature the application of human rights between private individuals. The paper then continues by discussing the application in virtual environments of two universally recognized human rights, namely freedom of expression, and freedom from discrimination. As these specific rights are discussed, a number of more general conclusions on the application of human rights in virtual environments are drawn. The first general conclusion being that, because virtual worlds are private environments, participants are subject to private ordering. The second general conclusion being that participants and non-participants alike have to accept at times that in-world expressions are to an extent private speech. The third general conclusion is that, where participants represent themselves in-world, other participants cannot assume that such in-world representation share the characteristics of the human player; and that where virtual environments contain game elements, participants and non-participants alike should not take everything that happens in the virtual environment at face value or literally, which does however not amount to having to accept a higher level of infringement on their rights for things that happen in such an environment.
Restyling the Humanities Curriculum of Higher Education for Posthuman Times
ERIC Educational Resources Information Center
Siddiqui, Jamila R.
2016-01-01
The future viability of the humanities in higher education has been broadly debated. Yet, most of these debates are missing an important consideration. The humanities' object of study is the human, an object that some would argue has been replaced in our onto-epistemological systems by the posthuman. In her 2013 book, "The Posthuman,"…
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.
RNA Duplex Map in Living Cells Reveals Higher-Order Transcriptome Structure.
Lu, Zhipeng; Zhang, Qiangfeng Cliff; Lee, Byron; Flynn, Ryan A; Smith, Martin A; Robinson, James T; Davidovich, Chen; Gooding, Anne R; Goodrich, Karen J; Mattick, John S; Mesirov, Jill P; Cech, Thomas R; Chang, Howard Y
2016-05-19
RNA has the intrinsic property to base pair, forming complex structures fundamental to its diverse functions. Here, we develop PARIS, a method based on reversible psoralen crosslinking for global mapping of RNA duplexes with near base-pair resolution in living cells. PARIS analysis in three human and mouse cell types reveals frequent long-range structures, higher-order architectures, and RNA-RNA interactions in trans across the transcriptome. PARIS determines base-pairing interactions on an individual-molecule level, revealing pervasive alternative conformations. We used PARIS-determined helices to guide phylogenetic analysis of RNA structures and discovered conserved long-range and alternative structures. XIST, a long noncoding RNA (lncRNA) essential for X chromosome inactivation, folds into evolutionarily conserved RNA structural domains that span many kilobases. XIST A-repeat forms complex inter-repeat duplexes that nucleate higher-order assembly of the key epigenetic silencing protein SPEN. PARIS is a generally applicable and versatile method that provides novel insights into the RNA structurome and interactome. VIDEO ABSTRACT. PMID:27180905
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…
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…
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 items found that the…
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…
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…
A Lagrangian description of the higher-order Painlevé equations
NASA Astrophysics Data System (ADS)
Ghose Choudhury, A.; Guha, Partha; Kudryashov, N. A.
2012-05-01
We derive the Lagrangians of the higher-order Painlevé equations using Jacobi's last multiplier technique. Some of these higher-order differential equations display certain remarkable properties like passing the Painlevé test and satisfy the conditions stated by Juráš, thus allowing for a Lagrangian description.
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…
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…
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…
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…
ERIC Educational Resources Information Center
Hubbs-Tait, Laura; Page, Melanie C.; Huey, Erron L.; Starost, Huei-Juang; Culp, Anne McDonald; Culp, Rex E.; Harper, M. Elizabeth
2006-01-01
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…
Classical and higher-order sliding mode attitude control for launch vehicle systems
NASA Astrophysics Data System (ADS)
Stott, James Edward, Jr.
In determining flight controls for launch vehicle systems, several things must be taken into account. Launch vehicle systems can be expendable or reusable, carry crew or cargo, etc. Each of these launch vehicles maneuvers through a wide range of flight conditions and different mission profiles. Crewed vehicles must adhere to human rating requirements which limit the angular rates. Reusable launch vehicle systems must take into account actuator saturation during entry. Wind disturbances and plant uncertainties are major perturbations to the nominal state of any launch vehicle. An ideal controller is one that is robust enough to handle these uncertainties and external disturbances with limited control authority. One major challenge that exists in the design of these vehicles is the updating of old autopilot technology to new robust designs while also taking into account the different type of launch vehicle system employed. Sliding mode control algorithms that are inherently robust to external disturbances and plant uncertainties are very good candidates for improving the robustness and accuracy of the flight control systems. This dissertation focuses on systematically studying and developing a 'toolbox' of classical and higher-order sliding mode attitude control algorithms for different types of launch vehicle systems operating in uncertain conditions, including model uncertainties, actuator malfunctions, and external perturbations such as wind gusts. The developed toolbox comprises of time-varying sliding variables, classical and higher-order sliding mode attitude control algorithms, and observer techniques that yield novel sliding mode attitude control architectures. The proposed control toolbox allows achieving even higher standards of performance, reliability, safety, operability, and cost for launch vehicles over the current state of the art. Case studies include controlling the X-33 and SLV-X Launch Vehicles studied under NASA's Space Launch Initiative (SLI
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 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.
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
2016-07-01
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.
NASA Astrophysics Data System (ADS)
Gong, Dewei; Chen, Changqing; Tian, Hao; Zhou, Zhongxiang
2012-09-01
We report some electric field controlled photorefractive higher-order diffraction phenomena of a paraelectric phase potassium lithium tantalate niobate crystal doped with iron. In experiments, a p-polarized semiconductor laser (532 nm) was used to record grating at a small incident angle. Higher-order diffraction images were observed when the signal beam was focused behind and in front of the crystal. Then the higher-order diffraction images were reconstructed by a p-polarized He-Ne laser (632.8 nm) in the direction perpendicular to the surface. The higher-order diffraction images could be controlled by the external electric field. A theory about the higher-order diffraction images of the K and 2K grating is developed. The results show that the even order diffraction images of the K grating and the odd order diffraction of the 2K grating overlap each other. The odd order diffraction images of the K grating are diffracted in unattached direction. The electric field controlled higher-order diffraction image provides a useful method for optical information processing.
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 construction problems…
NASA Astrophysics Data System (ADS)
Suri, Manil
1990-01-01
We investigate the use of higher-order mixed methods for second-order elliptic problems by establishing refined stability and convergence estimates which take into account both the mesh size h and polynomial degree p. Our estimates yield asymptotic convergence rates for the p- and h - p-versions of the finite element method. They also describe more accurately than previously proved estimates the increased rate of convergence expected when the h-version is used with higher-order polynomials. For our analysis, we choose the Raviart-Thomas and the Brezzi-Douglas-Marini elements and establish optimal rates of convergence in both h and p (up to arbitrary \\varepsilon > 0 ).
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
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. PMID:25602439
Perceptual information for the age level of faces as a higher order invariant of growth.
Pittenger, J B; Shaw, R E; Mark, L S
1979-08-01
Previous work supports the hypothesis that cardioidal strain, a nonlinear topological transformation, offers a plausible mathematical model for the perceived global changes in human craniofacial morphology due to growth. Experiment 1 examined the generality of the effect of this growth transformation on relative age judgments by applying it to profiles of a dog, bird, and monkey. Experiment 2 investigated the abstractness of this transformation by looking at its effect on perceived age level of a Volkswagen "Beetle." In both experiments, cardioidal strain resulted in changes in the perceived age of the nonhuman profiles that were similar to those produced on human faces in earlier work. A second transformation, affine shear, failed to produce as significant an effect on perceived age as cardioidal strain when applied to the same structures. Because cardioidal strain produces changes in structures that do not share an isomorphism of rigid (Euclidian) local features or rigid feature configurations, this transformation seems both sufficiently general and abstract to specify what J.J. Gibson has called a "higher-order invariant of perceptual information. PMID:528953
Cytosolic chaperones mediate quality control of higher-order septin assembly in budding yeast
Johnson, Courtney R.; Weems, Andrew D.; Brewer, Jennifer M.; Thorner, Jeremy; McMurray, Michael A.
2015-01-01
Septin hetero-oligomers polymerize into cytoskeletal filaments with essential functions in many eukaryotic cell types. Mutations within the oligomerization interface that encompasses the GTP-binding pocket of a septin (its “G interface”) cause thermoinstability of yeast septin hetero-oligomer assembly, and human disease. When coexpressed with its wild-type counterpart, a G interface mutant is excluded from septin filaments, even at moderate temperatures. We show that this quality control mechanism is specific to G interface mutants, operates during de novo septin hetero-oligomer assembly, and requires specific cytosolic chaperones. Chaperone overexpression lowers the temperature permissive for proliferation of cells expressing a G interface mutant as the sole source of a given septin. Mutations that perturb the septin G interface retard release from these chaperones, imposing a kinetic delay on the availability of nascent septin molecules for higher-order assembly. Unexpectedly, the disaggregase Hsp104 contributes to this delay in a manner that does not require its “unfoldase” activity, indicating a latent “holdase” activity toward mutant septins. These findings provide new roles for chaperone-mediated kinetic partitioning of non-native proteins and may help explain the etiology of septin-linked human diseases. PMID:25673805
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.
Higher-order mass defect analysis for mass spectra of complex organic mixtures.
Roach, Patrick J; Laskin, Julia; Laskin, Alexander
2011-06-15
Higher-order mass defect analysis is introduced as a unique formula assignment and visualization method for the analysis of complex mass spectra. This approach is an extension of the concepts of Kendrick mass transformation widely used for identification of homologous compounds differing only by a number of base units (e.g., CH(2), H(2), O, CH(2)O, etc.) in complex mixtures. We present an iterative renormalization routine for defining higher-order homologous series and multidimensional clustering of mass spectral features. This approach greatly simplifies visualization of complex mass spectra and increases the number of chemical formulas that can be confidently assigned for given mass accuracy. The potential for using higher-order mass defects for data reduction and visualization is shown. Higher-order mass defect analysis is described and demonstrated through third-order analysis of a deisotoped high-resolution mass spectrum of crude oil containing nearly 13,000 peaks. PMID:21526851
The Quality of Higher Humanities Education: A Roundtable
ERIC Educational Resources Information Center
Russian Education and Society, 2007
2007-01-01
This article presents excerpts from a debate on the report by Professor A.S. Zapesotskii, the rector of the St. Petersburg Trade Unions University of the Humanities, titled "Ensuring the Quality of Higher Humanities Education." Participants in the debate were as follows: (1)Antonina Pavlovna Beliaeva, a doctor of pedagogical sciences, professor,…
Luo, Ruiyao; Li, Lei; Cui, Wenda; Yang, Zining; Wang, Hongyan; Xu, Xiaojun
2016-06-13
In this paper, we have set up a diode laser pumped rubidium amplifier for higher-order Laguerre-Gauss (LG) modes. We experimentally realized amplification of higher-order LG modes including helical and sinusoidal LG_{03}, LG_{13}, LG_{23}, and LG_{33} modes with their high purity held. This novel scheme of generating high-purity higher-order LG beams at high laser power is preferred to the second-generation gravitational wave interferometers. To the best of our knowledge, it is the first time this scheme is formulated. PMID:27410352
Modulational instability of a modified Gross-Pitaevskii equation with higher-order nonlinearity.
Qi, Xiu-Ying; Xue, Ju-Kui
2012-07-01
We consider the modulational instability (MI) of Bose-Einstein condensate (BEC) described by a modified Gross-Pitaevskii (GP) equation with higher-order nonlinearity both analytically and numerically. A new explicit time-dependent criterion for exciting the MI is obtained. It is shown that the higher-order term can either suppress or enhance the MI, which is interesting for control of the system instability. Importantly, we predict that with the help of the higher-order nonlinearity, the MI can also take place in a BEC with repulsively contact interactions. The analytical results are confirmed by direct numerical simulations. PMID:23005569
Higher-Order Spectral Analysis of a Nonlinear Pitch and Plunge Apparatus
NASA Technical Reports Server (NTRS)
Silva, Walter A.; Strganac, Thomas W.; Hajj, Muhammad R.
2005-01-01
Simulated aeroelastic responses of a nonlinear pitch and plunge apparatus are analyzed using various statistical signal processing techniques including higher-order spectral methods. A MATLAB version of the Nonlinear Aeroelastic Testbed Apparatus (NATA) at the Texas A&M University is used to generate various aeroelastic response data including limit cycle oscillations (LCO). Traditional and higher-order spectral (HOS) methods are applied to the simulated aeroelastic responses. Higher-order spectral methods are used to identify critical signatures that indicate the transition from linear to nonlinear (LCO) aeroelastic behavior.
Nonlocal Symmetry Reductions, CTE Method and Exact Solutions for Higher-Order KdV Equation
NASA Astrophysics Data System (ADS)
Ren, Bo; Liu, Xi-Zhong; Liu, Ping
2015-02-01
The nonlocal symmetries for the higher-order KdV equation are obtained with the truncated Painlevé method. The nonlocal symmetries can be localized to the Lie point symmetries by introducing suitable prolonged systems. The finite symmetry transformations and similarity reductions for the prolonged systems are computed. Moreover, the consistent tanh expansion (CTE) method is applied to the higher-order KdV equation. These methods lead to some novel exact solutions of the higher-order KdV system.
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.
The Use of Higher-Order Difference Methods in Beam Vibration Analysis
NASA Technical Reports Server (NTRS)
Greenwood, Donald T.
1961-01-01
Simple and higher-order difference methods for the solution for the natural frequencies of vibration of a uniform beam are compared. The same basic higher-order method is used throughout for the interior cells, but three different methods of boundary-condition representation are given. Tables and graphs of the error in mode frequencies, as compared with a continuous beam, are given for the various methods as a function of the number of cells. It is concluded that higher-order methods improve accuracy for a given number of cells, with essentially no change in the quantity of computing equipment required.
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.
Effective higher-order nonlinear coefficients of composites with weakly nonlinear media
NASA Astrophysics Data System (ADS)
Natenapit, Mayuree; Thongboonrithi, Chaivej
2010-05-01
The field equations, based on the third-order perturbation expansion of electrostatic potential, are derived, and our general formulae for higher-order effective nonlinear coefficients based on the energy definition, are presented and applied to dielectric composites consisting of dilute linear cylindrical inclusions randomly dispersed in a weakly nonlinear host media. The effective nonlinear coefficients are determined up to the ninth order. In addition, the results are also compared to those obtained using the average field method and likely to provide more accurate predictions of effective higher-order nonlinear responses.
Higher order corrections and unification in the minimal supersymmetric standard model: SOFTSUSY3.5
NASA Astrophysics Data System (ADS)
Allanach, B. C.; Bednyakov, A.; Ruiz de Austri, R.
2015-04-01
We explore the effects of three-loop minimal supersymmetric standard model renormalisation group equation terms and some leading two-loop threshold corrections on gauge and Yukawa unification: each being one loop higher order than current public spectrum calculators. We also explore the effect of the higher order terms (often 2-3 GeV) on the lightest CP even Higgs mass prediction. We illustrate our results in the constrained minimal supersymmetric standard model. Neglecting threshold corrections at the grand unified scale, the discrepancy between the unification scale αs and the other two unified gauge couplings changes by 0.1% due to the higher order corrections and the difference between unification scale bottom-tau Yukawa couplings neglecting unification scale threshold corrections changes by up to 1%. The difference between unification scale bottom and top Yukawa couplings changes by a few percent. Differences due to the higher order corrections also give an estimate of the size of theoretical uncertainties in the minimal supersymmetric standard model spectrum. We use these to provide estimates of theoretical uncertainties in predictions of the dark matter relic density (which can be of order one due to its strong dependence on sparticle masses) and the LHC sparticle production cross-section (often around 30%). The additional higher order corrections have been incorporated into SOFTSUSY, and we provide details on how to compile and use the program. We also provide a summary of the approximations used in the higher order corrections.
Evidence of higher-order effects in thermally driven rapid granular flows
NASA Astrophysics Data System (ADS)
Hrenya, C. M.; Galvin, J. E.; Wildman, R. D.
Molecular dynamic (MD) simulations are used to probe the ability of Navier heat flux, stress tensor and dissipation rate - associated with granular materials. The system under investigation is bounded by two opposite walls of set granular temperature and is characterized by zero mean flow. The comparisons between MD and theory provide evidence of higher-order effects in each of the constitutive quantities. Furthermore, the size of these effects is roughly one order of magnitude greater, on a percentage basis, for heat flux than it is for stress or dissipation rate. For the case of heat flux, these effects are attributed to super-Burnett-order contributions (third order in gradients) or greater, since Burnett-order contributions to the heat flux do not exist. Finally, for the system considered, these higher-order contributions to the heat flux outweigh the first-order contribution arising from a gradient in concentration (i.e. the Dufour effect)
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.
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.
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. PMID:26705332
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.
The Structure and Dynamics of Higher-Order Assemblies: Amyloids, Signalosomes, and Granules.
Wu, Hao; Fuxreiter, Monika
2016-05-19
We here attempt to achieve an integrated understanding of the structure and dynamics of a number of higher-order assemblies, including amyloids, various kinds of signalosomes, and cellular granules. We propose that the synergy between folded domains, linear motifs, and intrinsically disordered regions regulates the formation and intrinsic fuzziness of all higher-order assemblies, creating a structural and dynamic continuum. We describe how such regulatory mechanisms could be influenced under pathological conditions. PMID:27203110
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.
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.
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…
"What Do I Do Here?": Higher Order Learning Effects of Enhancing Task Instructions
ERIC Educational Resources Information Center
Chamberlain, Susanna; Zuvela, Danni
2014-01-01
This paper reports the findings of a one-year research project focused on a series of structured interventions aimed at enhancing task instruction to develop students' understanding of higher assessment practices, and encouraging higher order learning. It describes the nature and iterations of the interventions, made into a large-enrolment online…
Higher-order asymptotics and critical indexes in the ϕ3 theory
NASA Astrophysics Data System (ADS)
Kalagov, G. A.; Nalimov, M. Yu.
2014-07-01
Instanton analysis is applied to the scalar ϕ3 theory. Higher-order asymptotic expansions of the renormalization constants in the minimal subtraction scheme and 6-ɛ dimensional regularization and of the index η are found. Results of the Borel resummation for the presently known terms of the ɛ-expansion of the index η up to the order ɛ4 are presented.
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…
Development of a Process To Assess Higher Order Thinking Skills for College Graduates.
ERIC Educational Resources Information Center
Rock, Donald A.
Issues in the development of assessments of higher order thinking skills for college graduates are discussed in the order in which they were presented when this series of papers was commissioned. With regard to Issue 1, it is generally agreed that the development of these skills is a desirable goal, but there is little consensus on how they should…
Efficient nonlinear generation of high power, higher order, ultrafast "perfect" vortices in green.
Apurv Chaitanya, N; Jabir, M V; Samanta, G K
2016-04-01
We report on efficient nonlinear generation of ultrafast, higher order "perfect" vortices at the green wavelength. Based on Fourier transformation of the higher order Bessel-Gauss (BG) beam generated through the combination of the spiral phase plate and axicon, we have transformed the Gaussian beam of the ultrafast Yb-fiber laser at 1060 nm into perfect vortices of power 4.4 W and order up to 6. Using single-pass second-harmonic generation (SHG) of such vortices in 5 mm long chirped MgO-doped, periodically poled congruent LiNbO_{3} crystal, we have generated perfect vortices at green wavelength (530 nm) with output power of 1.2 W and vortex order up to 12 at a single-pass conversion efficiency of 27%, independent of the orders. This is the highest single-pass SHG efficiency of any optical beams other than Gaussian beams. Unlike the disintegration of higher order vortices due to spatial walk-off effect in birefringent crystals, here, the use of the quasi-phase-matching process enables generation of high-quality vortices, even at higher orders. The green perfect vortices of all orders have temporal and spectral widths of 507 fs and 1.9 nm, respectively, corresponding to a time-bandwidth product of 1.02. PMID:27192233
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,…
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.
Effect of Higher-Order Spherical Aberration Term on Transfer Function in Electron Microscopy
NASA Astrophysics Data System (ADS)
Uchida, Yuji; Fujimoto, Fuminori
1986-04-01
The effect of the higher-order spherical aberration coefficient on the transfer function in transmission electron microscopy was calculated. In order to simplify the system, the optical illumination system was assumed to be perfectly coherent and axially symmetric. The result shows that the effect of the fifth-order spherical aberration coefficient, C5, on the usual transfer function with the third-order spherical aberration coefficient Cs\\equivC3{=}0.5 mm for 100 keV electrons cannot be neglected, if high-order Bragg reflections from net planes with smaller lattice spacings than 0.1 nm are utilized for lattice imaging. The effect of the higher-order term due to the defocussing on the transfer function is also discussed.
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.
Spectral Line Profile Analysis Using Higher Diffraction Order in Vacuum Ultraviolet Region
Machida, M.; Daltrini, A. M.; Severo, J. H. F.; Nascimento, I. C.; Sanada, E. K.; Elizondo, J. I.; Kuznetsov, Y. K.; Galvao, R. M. O.
2008-04-07
Using a one meter VUV spectrometer and a MCP coupled to a CCD detector on TCABR tokamak, ion temperatures from impurity species have been measured and much better spectral resolution was obtained using higher order diffraction lines. Due to very small Doppler effect in the VUV region compared to large instrumental broadening, ion temperatures obtained from first order diffraction present large errors. The use of second, third and fourth order diffraction emissions increases the line broadening and results in lower error temperature measurements.
Higher order solutions to ion-acoustic solitons in a weakly relativistic two-fluid plasma
Gill, Tarsem Singh; Bala, Parveen; Kaur, Harvinder
2008-12-15
The nonlinear wave structure of small amplitude ion-acoustic solitary waves (IASs) is investigated in a two-fluid plasma consisting of weakly relativistic streaming ions and electrons. Using the reductive perturbation theory, the basic set of governing equations is reduced to the Korteweg-de Vries (KdV) equation for the lowest order perturbation. This analysis is further extended using the renormalization technique for the inclusion of higher order nonlinear and dispersive effects for better accuracy. The effect of higher order correction and various parameters on the soliton characteristics is investigated and also discussed.
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.
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.
Higher-order suppression in an on-blaze plane-grating monochromator
Hunter, W.R.; Rife, J.C.
1984-01-15
The transmittance of an on-blaze plane-grating monochromator has been calculated as a function of wavelength for different spectral orders. The calculations show that higher, undesirable orders can be suppressed by a judicious selection of grating blaze angle and coating material. However, for intense sources, such as storage ring operating at high power and current, higher-order suppression due to blaze angle and coating material may have to be augmented by using transmitting filters or spectrally selective detectors or both.
Proper orthogonal decomposition-based spectral higher-order stochastic estimation
NASA Astrophysics Data System (ADS)
Baars, Woutijn J.; Tinney, Charles E.
2014-05-01
A unique routine, capable of identifying both linear and higher-order coherence in multiple-input/output systems, is presented. The technique combines two well-established methods: Proper Orthogonal Decomposition (POD) and Higher-Order Spectra Analysis. The latter of these is based on known methods for characterizing nonlinear systems by way of Volterra series. In that, both linear and higher-order kernels are formed to quantify the spectral (nonlinear) transfer of energy between the system's input and output. This reduces essentially to spectral Linear Stochastic Estimation when only first-order terms are considered, and is therefore presented in the context of stochastic estimation as spectral Higher-Order Stochastic Estimation (HOSE). The trade-off to seeking higher-order transfer kernels is that the increased complexity restricts the analysis to single-input/output systems. Low-dimensional (POD-based) analysis techniques are inserted to alleviate this void as POD coefficients represent the dynamics of the spatial structures (modes) of a multi-degree-of-freedom system. The mathematical framework behind this POD-based HOSE method is first described. The method is then tested in the context of jet aeroacoustics by modeling acoustically efficient large-scale instabilities as combinations of wave packets. The growth, saturation, and decay of these spatially convecting wave packets are shown to couple both linearly and nonlinearly in the near-field to produce waveforms that propagate acoustically to the far-field for different frequency combinations.
Proper orthogonal decomposition-based spectral higher-order stochastic estimation
Baars, Woutijn J.; Tinney, Charles E.
2014-05-15
A unique routine, capable of identifying both linear and higher-order coherence in multiple-input/output systems, is presented. The technique combines two well-established methods: Proper Orthogonal Decomposition (POD) and Higher-Order Spectra Analysis. The latter of these is based on known methods for characterizing nonlinear systems by way of Volterra series. In that, both linear and higher-order kernels are formed to quantify the spectral (nonlinear) transfer of energy between the system's input and output. This reduces essentially to spectral Linear Stochastic Estimation when only first-order terms are considered, and is therefore presented in the context of stochastic estimation as spectral Higher-Order Stochastic Estimation (HOSE). The trade-off to seeking higher-order transfer kernels is that the increased complexity restricts the analysis to single-input/output systems. Low-dimensional (POD-based) analysis techniques are inserted to alleviate this void as POD coefficients represent the dynamics of the spatial structures (modes) of a multi-degree-of-freedom system. The mathematical framework behind this POD-based HOSE method is first described. The method is then tested in the context of jet aeroacoustics by modeling acoustically efficient large-scale instabilities as combinations of wave packets. The growth, saturation, and decay of these spatially convecting wave packets are shown to couple both linearly and nonlinearly in the near-field to produce waveforms that propagate acoustically to the far-field for different frequency combinations.
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.
NASA Astrophysics Data System (ADS)
Liu, Kai; Tian, Jie, Sr.; Qin, Chenghu; Yang, Xin; Zhu, Shouping; Han, Dong; Wu, Ping; Dai, Xiaoqian
2011-03-01
In vivo bioluminescence imaging (BLI) has played a more and more important role in biomedical research of small animals. Tomographic bioluminescence imaging (TBI) further translates the BLI optical information into three-dimensional bioluminescent source distribution, which could greatly facilitate applications in related studies. Although the diffusion approximation (DA) is one of the most widely-used forward models, higher-order approximations are still needed for in vivo small animal imaging. In this work, as a relatively accurate and higher-order approximation theory, a simplified spherical harmonics approximation (SPN) is applied for heterogeneous tomographic bioluminescence imaging in vivo. Furthermore, coupled with the SPN, a generalized graph cuts optimization approach is utilized, making BLT reconstructions fast and suit for the whole body of small animals. Heterogeneous in vivo experimental reconstructions via the higher-order approximation model demonstrate higher tomographic imaging quality, which is shown the capability for practical biomedical tomographic imaging applications.
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.
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
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.
Bounding higher-order ionosphere errors for the dual-frequency GPS user
NASA Astrophysics Data System (ADS)
Datta-Barua, S.; Walter, T.; Blanch, J.; Enge, P.
2008-10-01
Civil signals at L2 and L5 frequencies herald a new phase of Global Positioning System (GPS) performance. Dual-frequency users typically assume a first-order approximation of the ionosphere index of refraction, combining the GPS observables to eliminate most of the ranging delay, on the order of meters, introduced into the pseudoranges. This paper estimates the higher-order group and phase errors that occur from assuming the ordinary first-order dual-frequency ionosphere model using data from the Federal Aviation Administration's Wide Area Augmentation System (WAAS) network on a solar maximum quiet day and an extremely stormy day postsolar maximum. We find that during active periods, when ionospheric storms may introduce slant range delays at L1 as high as 100 m, the higher-order group errors in the L1-L2 or L1-L5 dual-frequency combination can be tens of centimeters. The group and phase errors are no longer equal and opposite, so these errors accumulate in carrier smoothing of the dual-frequency code observable. We show the errors in the carrier-smoothed code are due to higher-order group errors and, to a lesser extent, to higher-order phase rate errors. For many applications, this residual error is sufficiently small as to be neglected. However, such errors can impact geodetic applications as well as the error budgets of GPS Augmentation Systems providing Category III precision approach.
Recognition of viruses by electron microscopy using higher order spectral features
NASA Astrophysics Data System (ADS)
Ong, C. L. H.; Chandran, Vinod
2003-05-01
A limitation of using electron microscopy as a diagnostic tool in virology is the expertise required in analysing and interpreting the images. EM images of different viruses can be very similar in shape. An automated recognition method is proposed in this paper. It is based on radial spectra of higher-order spectral parameters robust to translation, scaling and noise. These features are also roation invariant and can be averaged for a population of viral particles without the need to normalize and align them. They extract symmetry information and are sensitive enough to distinguish viruses that appear nearly circular to the human eye. The method was tested using three such viruses with very similar morphologies - the Adeno, the HAV and the Astro. 70 viral particles of each class from three images were used for training. In the first test, random unseen sets of viral particles form the same images were chosen. In the second test, images of viruses from other sources, where the specimen preparation and the microscope are different, were used to determine the reliability of the system. Both tests have shown high classification accuracy improving rapidly to 100% as the test ensemble grew to 20 particles.
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.
A Hypergraph-Based Reduction for Higher-Order Binary Markov Random Fields.
Fix, Alexander; Gruber, Aritanan; Boros, Endre; Zabih, Ramin
2015-07-01
Higher-order Markov Random Fields, which can capture important properties of natural images, have become increasingly important in computer vision. While graph cuts work well for first-order MRF's, until recently they have rarely been effective for higher-order MRF's. Ishikawa's graph cut technique [1], [2] shows great promise for many higher-order MRF's. His method transforms an arbitrary higher-order MRF with binary labels into a first-order one with the same minima. If all the terms are submodular the exact solution can be easily found; otherwise, pseudoboolean optimization techniques can produce an optimal labeling for a subset of the variables. We present a new transformation with better performance than [1], [2], both theoretically and experimentally. While [1], [2] transforms each higher-order term independently, we use the underlying hypergraph structure of the MRF to transform a group of terms at once. For n binary variables, each of which appears in terms with k other variables, at worst we produce n non-submodular terms, while [1], [2] produces O(nk). We identify a local completeness property under which our method perform even better, and show that under certain assumptions several important vision problems (including common variants of fusion moves) have this property. We show experimentally that our method produces smaller weight of non-submodular edges, and that this metric is directly related to the effectiveness of QPBO [3]. Running on the same field of experts dataset used in [1], [2] we optimally label significantly more variables (96 versus 80 percent) and converge more rapidly to a lower energy. Preliminary experiments suggest that some other higher-order MRF's used in stereo [4] and segmentation [5] are also locally complete and would thus benefit from our work. PMID:26352447
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.
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.
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.
On the asymptotic solutions of the KdV equation with higher-order corrections
NASA Astrophysics Data System (ADS)
Burde, Georgy I.
2005-07-01
A method for construction of new integrable PDEs, whose properties are related to an asymptotic perturbation expansion with the leading-order term given by an integrable equation, is developed. A new integrable equation is constructed by applying the properly defined Lie-Bäcklund group of transformations to the leading-order equation. The integrable equations related to the Korteweg-de Vries (KdV) equation with higher-order corrections are used to investigate the limits of applicability of the so-called asymptotic integrability concept. It is found that the solutions of the higher-order KdV equations obtained by a near identity transform from the normal form solitary waves cannot, in principle, describe some intrinsic features of the high-order KdV solitons.
Gavrishchaka, V.V.; Ganguli, G.I.; Bakshi, P.M.; Koepke, M.E.
1998-01-01
The formalism necessary to study the collective properties of a plasma system with inhomogeneous flows is nonlocal and generally in the form of an integrodifferential equation. Usually the eigenvalue condition is reduced to a second-order differential equation for simplicity. While the gross physical behavior of the system can be obtained from the second-order differential equation level of description, higher-order corrections are necessary for greater accuracy. The limit in which the scale-size of the velocity inhomogeneity is large compared to the ion gyroradius is considered and a transverse flow profile sharply localized in space ({open_quotes}top-hat{close_quotes} profile) is assumed. In this limit, a simple analytical method for the solution of the general eigenvalue condition to all orders is developed. A comparison of the properties of the solutions obtained from the second-order differential equation level of description with those obtained from higher orders is presented. Both the resonant (dissipative) and the nonresonant (reactive) effects of velocity shear are considered. It is found that while the overall features are well represented by the second-order level of description, the higher-order corrections moderate the destabilizing effects due to velocity shear, which can be quite significant in some cases. {copyright} {ital 1998 American Institute of Physics.}
Staude, Benjamin; Grün, Sonja; Rotter, Stefan
2009-01-01
The extent to which groups of neurons exhibit higher-order correlations in their spiking activity is a controversial issue in current brain research. A major difficulty is that currently available tools for the analysis of massively parallel spike trains (N >10) for higher-order correlations typically require vast sample sizes. While multiple single-cell recordings become increasingly available, experimental approaches to investigate the role of higher-order correlations suffer from the limitations of available analysis techniques. We have recently presented a novel method for cumulant-based inference of higher-order correlations (CuBIC) that detects correlations of higher order even from relatively short data stretches of length T = 10–100 s. CuBIC employs the compound Poisson process (CPP) as a statistical model for the population spike counts, and assumes spike trains to be stationary in the analyzed data stretch. In the present study, we describe a non-stationary version of the CPP by decoupling the correlation structure from the spiking intensity of the population. This allows us to adapt CuBIC to time-varying firing rates. Numerical simulations reveal that the adaptation corrects for false positive inference of correlations in data with pure rate co-variation, while allowing for temporal variations of the firing rates has a surprisingly small effect on CuBICs sensitivity for correlations. PMID:20725510
A Maximum Entropy Test for Evaluating Higher-Order Correlations in Spike Counts
Onken, Arno; Dragoi, Valentin; Obermayer, Klaus
2012-01-01
Evaluating the importance of higher-order correlations of neural spike counts has been notoriously hard. A large number of samples are typically required in order to estimate higher-order correlations and resulting information theoretic quantities. In typical electrophysiology data sets with many experimental conditions, however, the number of samples in each condition is rather small. Here we describe a method that allows to quantify evidence for higher-order correlations in exactly these cases. We construct a family of reference distributions: maximum entropy distributions, which are constrained only by marginals and by linear correlations as quantified by the Pearson correlation coefficient. We devise a Monte Carlo goodness-of-fit test, which tests - for a given divergence measure of interest - whether the experimental data lead to the rejection of the null hypothesis that it was generated by one of the reference distributions. Applying our test to artificial data shows that the effects of higher-order correlations on these divergence measures can be detected even when the number of samples is small. Subsequently, we apply our method to spike count data which were recorded with multielectrode arrays from the primary visual cortex of anesthetized cat during an adaptation experiment. Using mutual information as a divergence measure we find that there are spike count bin sizes at which the maximum entropy hypothesis can be rejected for a substantial number of neuronal pairs. These results demonstrate that higher-order correlations can matter when estimating information theoretic quantities in V1. They also show that our test is able to detect their presence in typical in-vivo data sets, where the number of samples is too small to estimate higher-order correlations directly. PMID:22685392
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.
Superintegrability and higher-order constants for classical and quantum systems
NASA Astrophysics Data System (ADS)
Kalnins, E. G.; Miller, W.; Pogosyan, G. S.
2011-06-01
We extend recent work by Tremblay, Turbiner, and Winternitz which analyzes an infinite family of solvable and integrable quantum systems in the plane, indexed by the positive parameter k. Key components of their analysis were to demonstrate that there are closed orbits in the corresponding classical system if k is rational, and for a number of examples there are generating quantum symmetries that are higher order differential operators than two. Indeed they conjectured that for a general class of potentials of this type, quantum constants of higher order should exist. We give credence to this conjecture by showing that for an even more general class of potentials in classicalmechanics, there are higher-order constants of the motion as polynomials in the momenta. Thus these systems are all superintegrable.
Superintegrability and higher-order constants for classical and quantum systems
Kalnins, E. G.; Miller, W.; Pogosyan, G. S.
2011-06-15
We extend recent work by Tremblay, Turbiner, and Winternitz which analyzes an infinite family of solvable and integrable quantum systems in the plane, indexed by the positive parameter k. Key components of their analysis were to demonstrate that there are closed orbits in the corresponding classical system if k is rational, and for a number of examples there are generating quantum symmetries that are higher order differential operators than two. Indeed they conjectured that for a general class of potentials of this type, quantum constants of higher order should exist. We give credence to this conjecture by showing that for an even more general class of potentials in classicalmechanics, there are higher-order constants of the motion as polynomials in the momenta. Thus these systems are all superintegrable.
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.
Temporal integration property of stereopsis after higher-order aberration correction
Kang, Jian; Dai, Yun; Zhang, Yudong
2015-01-01
Based on a binocular adaptive optics visual simulator, we investigated the effect of higher-order aberration correction on the temporal integration property of stereopsis. Stereo threshold for line stimuli, viewed in 550nm monochromatic light, was measured as a function of exposure duration, with higher-order aberrations uncorrected, binocularly corrected or monocularly corrected. Under all optical conditions, stereo threshold decreased with increasing exposure duration until a steady-state threshold was reached. The critical duration was determined by a quadratic summation model and the high goodness of fit suggested this model was reasonable. For normal subjects, the slope for stereo threshold versus exposure duration was about −0.5 on logarithmic coordinates, and the critical duration was about 200 ms. Both the slope and the critical duration were independent of the optical condition of the eye, showing no significant effect of higher-order aberration correction on the temporal integration property of stereopsis. PMID:26601010
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
Automatic tracking of ground station antennas by means of higher order waveguide modes
NASA Astrophysics Data System (ADS)
Scheffer, H.
1980-02-01
Utilization of higher order waveguide modes, which are excited in the feed when the satellite is displaced from the boresight axis of the antenna is discussed. The physical relations involved in the excitation of higher order waveguide modes as a function of the antenna position are explained. The starting points of these considerations are the radiation patterns of the tracking modes excited by feeds with circular and square cross sections. Special mention is made of the derivation of the offset information in the cases of circular and linear polarization of the beacon signal. The principle of selective mode coupling by means of tracking mode couplers is described. A compilation of German ground station antennas is given, which apply tracking by higher order waveguide modes.
Temporal integration property of stereopsis after higher-order aberration correction.
Kang, Jian; Dai, Yun; Zhang, Yudong
2015-11-01
Based on a binocular adaptive optics visual simulator, we investigated the effect of higher-order aberration correction on the temporal integration property of stereopsis. Stereo threshold for line stimuli, viewed in 550nm monochromatic light, was measured as a function of exposure duration, with higher-order aberrations uncorrected, binocularly corrected or monocularly corrected. Under all optical conditions, stereo threshold decreased with increasing exposure duration until a steady-state threshold was reached. The critical duration was determined by a quadratic summation model and the high goodness of fit suggested this model was reasonable. For normal subjects, the slope for stereo threshold versus exposure duration was about -0.5 on logarithmic coordinates, and the critical duration was about 200 ms. Both the slope and the critical duration were independent of the optical condition of the eye, showing no significant effect of higher-order aberration correction on the temporal integration property of stereopsis. PMID:26601010
Rapidity window dependences of higher order cumulants and diffusion master equation
NASA Astrophysics Data System (ADS)
Kitazawa, Masakiyo
2015-10-01
We study the rapidity window dependences of higher order cumulants of conserved charges observed in relativistic heavy ion collisions. The time evolution and the rapidity window dependence of the non-Gaussian fluctuations are described by the diffusion master equation. Analytic formulas for the time evolution of cumulants in a rapidity window are obtained for arbitrary initial conditions. We discuss that the rapidity window dependences of the non-Gaussian cumulants have characteristic structures reflecting the non-equilibrium property of fluctuations, which can be observed in relativistic heavy ion collisions with the present detectors. It is argued that various information on the thermal and transport properties of the hot medium can be revealed experimentally by the study of the rapidity window dependences, especially by the combined use, of the higher order cumulants. Formulas of higher order cumulants for a probability distribution composed of sub-probabilities, which are useful for various studies of non-Gaussian cumulants, are also presented.
Tanabe, Kentarou; Nagataki, Shigehiro
2008-07-15
The Blandford-Znajek mechanism, by which the rotational energy of a black hole is extracted through electromagnetic fields, is one of the promising candidates as an essential process of the central engine of active compact objects such as gamma-ray bursts. The only known analytical solution of this mechanism is the perturbative monopole solution for Kerr parameter a up to the second order terms. In order to apply the Blandford-Znajek mechanism to rapidly rotating black holes, we try to obtain the perturbation solution up to the fourth order. As a result, we find that the fourth order terms of the vector potential diverge at infinity, and this implies that the perturbation approach breaks down at a large distance from the black hole. Although there are some uncertainties about the solution due to the unknown boundary condition at infinity for the fourth order terms, we can derive the evaluation of the total energy flux extracted from the black hole up to fourth order of a without any ambiguity. Furthermore, from the comparison between the numerical solution, which is valid for 0order solution, we find that the fourth order solution reproduces the numerical result better than the second order solution. At the same time, since the fourth order solution does not match well with the numerical result at large a, we conclude that more higher order terms are required to reproduce the numerical result.
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(Zr1-xTix)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 nth order harmonic SPM detection methods in exploring nonlinear phenomena in nanoscale materials. PMID:24045269
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.
Wave train generation of solitons in systems with higher-order nonlinearities.
Mohamadou, Alidou; LatchioTiofack, C G; Kofané, Timoléon C
2010-07-01
Considering the higher-order nonlinearities in a material can significantly change its behavior. We suggest the extended nonlinear Schrödinger equation to describe the propagation of ultrashort optical pulses through a dispersive medium with higher-order nonlinearities. Soliton trains are generated through the modulational instability and we point out the influence of the septic nonlinearity in the modulational instability gain. Experimental values are used for the numerical simulations and the input plane wave leads to the development of pulse trains, depending upon the sign of the septic nonlinearity. PMID:20866749
Higher--order CO/sub 2/ laser beam spot size and depth of focus determined
Luxon, J.T.; Parker, D.E.
1981-06-01
Measurements of higher-order CO/sub 2/ laser beam spot size have been made and found in good agreement with a Hermite-Gaussian rectangular beam propagation model. A modified working definition of spot size is introduced, and a useful depth of focus relationship is presented. It is shown that a single measurement of spot size for any higher-order mode is all that is required to reasonably predict spot size for the same laser operating in different modes. Alternatively, beam size can be predicted theoretically on the basis of the optical cavity parameters.
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.
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
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.
NASA Astrophysics Data System (ADS)
Dori, Yehudit J.; Tal, Revital T.; Tsaushu, Masha
2003-11-01
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 skills. The research goal was to investigate nonscience major students' ability to use various thinking skills in analyzing environmental and moral conflicts presented through case studies in the Biotechnology Module. The research population consisted of about 200 nonscience majors in eight classes of grades 10-12 from heterogeneous communities. We found a significant improvement in students' knowledge and understanding and higher order thinking skills at all academic levels. The scores that low academic level students achieved in the knowledge and understanding category were higher than their high academic level peers' scores. In the higher order thinking skills - question posing, argumentation, and system thinking - a significant difference in favor of the high academic level students was found. The gap that had existed between low and high academic level students narrowed. Most students reported that the biotechnological topics that they had studied were interesting and relevant. Based on these results, we advocate a curriculum that exposes students to scientific controversies through case studies with environmental and moral implications. Our research has shown that this approach is likely to contribute to developing scientific and technological literacy along with higher order thinking skills of nonscience majors.
Evidence of Higher-Order Effects in Thermally-Driven, Rapid Granular Flows
Hrenya, C.M.; Galvin, J.E.; Wildman, R.D.
2008-01-01
Molecular dynamic (MD) simulations are used to probe the ability of Navier–Stokes-order theories to predict each of the constitutive quantities – heat flux, stress tensor and dissipation rate – associated with granular materials. The system under investigation is bounded by two opposite walls of set granular temperature and is characterized by zero mean flow. The comparisons between MD and theory provide evidence of higher-order effects in each of the constitutive quantities. Furthermore, the size of these effects is roughly one order of magnitude greater, on a percentage basis, for heat flux than it is for stress or dissipation rate. For the case of heat flux, these effects are attributed to super-Burnett-order contributions (third order in gradients) or greater, since Burnett-order contributions to the heat flux do not exist. Finally, for the system considered, these higher-order contributions to the heat flux outweigh the first-order contribution arising from a gradient in concentration (i.e. the Dufour effect).
Higher-order accurate Osher schemes with application to compressible boundary layer stability
NASA Technical Reports Server (NTRS)
Vandervegt, J. J. W.
1993-01-01
Two fourth order accurate Osher schemes are presented which maintain higher order accuracy on nonuniform grids. They use either a conservative finite difference or finite volume discretization. Both methods are successfully used for direct numerical simulations of flat plate boundary layer instability at different Mach numbers. Results of growth rates of Tollmien-Schlichting waves compare well with direct simulations of incompressible flow and for compressible flow with results obtained by solving the parabolic stability equations.
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.
Improvements to local projective noise reduction through higher order and multiscale refinements.
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. PMID:26117108
Feasibility of Higher-Order Differential Ion Mobility Separations Using New Asymmetric Waveforms
Shvartsburg, Alexandre A.; Mashkevich, Stefan V.; Smith, Richard D.
2011-01-01
Technologies for separating and characterizing ions based on their transport properties in gases have been around for three decades. The early method of ion mobility spectrometry (IMS) distinguished ions by absolute mobility that depends on the collision cross section with buffer gas atoms. The more recent technique of field asymmetric waveform IMS (FAIMS) measures the difference between mobilities at high and low electric fields. Coupling IMS and FAIMS to soft ionization sources and mass spectrometry (MS) has greatly expanded their utility, enabling new applications in biomedical and nanomaterials research. Here, we show that time-dependent electric fields comprising more than two intensity levels could, in principle, effect an infinite number of distinct differential separations based on the higher-order terms of expression for ion mobility. These analyses could employ the hardware and operational procedures similar to those utilized in FAIMS. Methods up to the 4th or 5th order (where conventional IMS is 1st order and FAIMS is 2nd order) should be practical at field intensities accessible in ambient air, with still higher orders potentially achievable in insulating gases. Available experimental data suggest that higher-order separations should be largely orthogonal to each other and to FAIMS, IMS, and MS. PMID:16494377
Does Higher-Order Thinking Impinge on Learner-Centric Digital Approach?
ERIC Educational Resources Information Center
Mathew, Bincy; Raja, B. William Dharma
2015-01-01
Humans are social beings and the social cognition focuses on how one form impressions of other people, interpret the meaning of other people's behaviour and how people's behaviour is affected by our attitudes. The school provides complex social situations and in order to thrive, students must possess social cognition, the process of thinking about…
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. PMID:26150070
Zhou, Yanyan; Luan, Feng; Gu, Bobo; Yu, Xia
2015-02-23
Metallic diffraction grating coupler is investigated for controlled excitation of whispering gallery modes (WGMs) of different radial orders. Based on effective mode index calculations and finite difference time domain method, it is found that higher radial order WGMs can be separated from the fundamental modes by sending them into the opposite propagation direction. By phase-matching designs, the metallic diffraction grating provides extra freedom to switch propagation directions, and is able to selectively enhance or suppress different radial-order WGMs. Such structure offers a simple and practical configuration for various WGM applications including liquid sensing, band pass filtering and fiber lasers. PMID:25836534
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
NASA Astrophysics Data System (ADS)
Stieberger, Stephan
2011-03-01
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 R5 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)R6 terms. Our analysis is valid for any superstring background in any space-time dimension, which allows for a conformal field theory description.
Selective excitation of higher order modes in hollow-core PCF via prism-coupling.
Trabold, Barbara M; Novoa, David; Abdolvand, Amir; Russell, Philip St J
2014-07-01
Prism-coupling through the microstructured cladding is used to selectively excite individual higher order modes in hollow-core photonic crystal fibers (PCFs). Mode selection is achieved by varying the angle between the incoming beam and the fiber axis, in order to match the axial wavevector component to that of the desired mode. The technique allows accurate measurement of the effective indices and transmission losses of modes of arbitrary order, even those with highly complex transverse field distributions that would be extremely difficult to excite by conventional endfire coupling. PMID:24978724
Second-Order Conditioning of Human Causal Learning
ERIC Educational Resources Information Center
Jara, Elvia; Vila, Javier; Maldonado, Antonio
2006-01-01
This article provides the first demonstration of a reliable second-order conditioning (SOC) effect in human causal learning tasks. It demonstrates the human ability to infer relationships between a cause and an effect that were never paired together during training. Experiments 1a and 1b showed a clear and reliable SOC effect, while Experiments 2a…
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
Swanson, Kena A.; Taylor, Lacey D.; Frank, Shaun D.; Sturdevant, Gail L.; Fischer, Elizabeth R.; Carlson, John H.; Whitmire, William M.; Caldwell, Harlan D.
2009-01-01
Chlamydia trachomatis is a globally important obligate intracellular bacterial pathogen that is a leading cause of sexually transmitted disease and blinding trachoma. Effective control of these diseases will likely require a preventative vaccine. C. trachomatis polymorphic membrane protein D (PmpD) is an attractive vaccine candidate as it is conserved among C. trachomatis strains and is a target of broadly cross-reactive neutralizing antibodies. We show here that immunoaffinity-purified native PmpD exists as an oligomer with a distinct 23-nm flower-like structure. Two-dimensional blue native-sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed that the oligomers were composed of full-length PmpD (p155) and two proteolytically processed fragments, the p73 passenger domain (PD) and the p82 translocator domain. We also show that PmpD undergoes an infection-dependent proteolytic processing step late in the growth cycle that yields a soluble extended PD (p111) that was processed into a p73 PD and a novel p30 fragment. Interestingly, soluble PmpD peptides possess putative eukaryote-interacting functional motifs, implying potential secondary functions within or distal to infected cells. Collectively, our findings show that PmpD exists as two distinct forms, a surface-associated oligomer exhibiting a higher-order flower-like structure and a soluble form restricted to infected cells. We hypothesize that PmpD is a multifunctional virulence factor important in chlamydial pathogenesis and could represent novel vaccine or drug targets for the control of human chlamydial infections. PMID:19001072
Higher order terms of radiative damping in extreme intense laser-matter interaction
Pandit, Rishi R.; Sentoku, Yasuhiko
2012-07-15
The higher order terms of the Lorentz-Abraham-Dirac equation have been derived, and their effects are studied via a relativistic collisional particle-in-cell simulation. The dominant group of terms up to the fourth order of the Lorentz-Abraham-Dirac equation is identified for ultra-intense laser-matter interactions. The second order terms are found to be the damping terms of the Lorentz force while the first order terms represent friction in the equation of motion. Because the second order terms restrict electron acceleration during the laser interaction, electrons/ions are prevented from over-accelerating. Radiative damping becomes highly significant when I{>=} 10{sup 22} W/cm{sup 2} while Bremsstrahlung will be saturated, thus radiative damping will be a dominant source of hard x-rays in regimes at extreme intensities.
HIGHER ORDER FACTOR STRUCTURE OF THE WISC-IV IN A CLINICAL NEUROPSYCHOLOGICAL SAMPLE
Bodin, Doug; Pardini, Dustin A.; Burns, Thomas G.; Stevens, Abigail B.
2010-01-01
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. PMID:19132580
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.
Computer Game Development: An Instructional Strategy to Promote Higher Order Thinking Skills
ERIC Educational Resources Information Center
Prayaga, Lakshmi; Coffey, John W.
2008-01-01
Several studies have demonstrated that games have been effectively used as an instructional strategy to motivate and engage students. This paper presents the use of the process of game development as an instructional strategy to promote higher order thinking skills. An analysis of the various aspects of game development including graphics,…
The HOTT Program. Higher Order Techno Thinking: Its Trials and Tribulations.
ERIC Educational Resources Information Center
Dowler, Earl R.; And Others
The Higher Order Techno Thinking (HOTT) Program was developed by a group of graduate students, who were experienced teachers, at the University of New Mexico. The objective was to develop an environment in which independent research, curriculum integration, multicultural awareness, and technology application could be integrated into a general or…
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…
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 skills. The research…
Problem-Based Learning and Use of Higher-Order Thinking by Emergency Medical Technicians
ERIC Educational Resources Information Center
Rosenberger, Paul
2013-01-01
Emergency Medical Technicians (EMTs) often handle chaotic life-and-death situations that require higher-order thinking skills. Improving the pass rate of EMT students depends on many factors, including the use of proven and effective teaching methods. Results from recent research about effective teaching have suggested that the instructional…
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…
Using Naturalistic Inquiry To Foster Higher Order Thinking in an Undergraduate Classroom.
ERIC Educational Resources Information Center
Gill, Helen V.
A teaching/learning strategy called "Content-Field Synergy" (C-FS) promotes systematic instruction in the use of naturalistic inquiry as a higher order thinking strategy in social context. C-FS is a total course of study design that synthesizes and extends material from the required course text and lectures with observations from a "relevant slice…
ERIC Educational Resources Information Center
Zohar, Anat
2006-01-01
This study examines the development of teachers' metastrategic knowledge (MSK), a component of metacognitive knowledge, in the context of higher order thinking. Participants were 14 junior high school and high school science teachers who attended a professional development course. Data collection was carried out by triangulation of several data…
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.
Development of a Curriculum To Enhance Adult Learners' Higher Order Skills. Final Report.
ERIC Educational Resources Information Center
Pennsylvania State Univ., University Park. Inst. for the Study of Adult Literacy.
This document consists of the final report and teacher handbook from a project conducted to develop a curriculum of information, strategies, and activities for adult basic education teachers, tutors, and counselors to use in helping adult students improve their higher order thinking skills. Findings of a review of the available literature on…
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 oligomerization promotes localization of SPOP to liquid nuclear speckles.
Marzahn, Melissa R; Marada, Suresh; Lee, Jihun; Nourse, Amanda; Kenrick, Sophia; Zhao, Huaying; Ben-Nissan, Gili; Kolaitis, Regina-Maria; Peters, Jennifer L; Pounds, Stanley; Errington, Wesley J; Privé, Gilbert G; Taylor, J Paul; Sharon, Michal; Schuck, Peter; Ogden, Stacey K; Mittag, Tanja
2016-06-15
Membrane-less organelles in cells are large, dynamic protein/protein or protein/RNA assemblies that have been reported in some cases to have liquid droplet properties. However, the molecular interactions underlying the recruitment of components are not well understood. Herein, we study how the ability to form higher-order assemblies influences the recruitment of the speckle-type POZ protein (SPOP) to nuclear speckles. SPOP, a cullin-3-RING ubiquitin ligase (CRL3) substrate adaptor, self-associates into higher-order oligomers; that is, the number of monomers in an oligomer is broadly distributed and can be large. While wild-type SPOP localizes to liquid nuclear speckles, self-association-deficient SPOP mutants have a diffuse distribution in the nucleus. SPOP oligomerizes through its BTB and BACK domains. We show that BTB-mediated SPOP dimers form linear oligomers via BACK domain dimerization, and we determine the concentration-dependent populations of the resulting oligomeric species. Higher-order oligomerization of SPOP stimulates CRL3(SPOP) ubiquitination efficiency for its physiological substrate Gli3, suggesting that nuclear speckles are hotspots of ubiquitination. Dynamic, higher-order protein self-association may be a general mechanism to concentrate functional components in membrane-less cellular bodies. PMID:27220849
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.…
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…
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…
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…
Comparison study between dyadic wavelet transform and modified higher order moment
NASA Astrophysics Data System (ADS)
Choupan, Jeiran; Ghorshi, Seyed; Mortazavi, Mohammad; Sepehrband, Farshid
2011-10-01
Pitch detection is the process of determining the period of the vocal cords closure or in another word the time duration of one glottal closed, open and returning phase. Dyadic wavelets transform (DyWT) and modified higher order moment, are two pitch detection methods. DyWT is an accurate pitch detection method, however it has less accuracy compared to modified higher order moment. On the other hand modified higher order moment has high computational complexity and is time consuming. The DyWT pitch period detection is based on a two pass dyadic wavelet transform over a signal. Modified higher order moment is based on autocorrelation function (ACF) and in this method the speech signal has been split into a positive-amplitude and a negative-amplitude. For window length selection a larger window length that consists of current and several past frames followed by a smaller window length is used. In this paper we try to compare these two pitch detection methods in terms of accuracy, computational complexity and robustness to noise.
Writing Multiple-Choice Items to Measure Higher-Order Educational Objectives.
ERIC Educational Resources Information Center
Aiken, Lewis R.
1982-01-01
Five types of multiple-choice items that can be used to assess higher-order educational objectives are examined. The item types do not exhaust the possibilities, but they are standard forms found helpful in writing items to measure more than recognitive memory. (Author/CM)
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. PMID:26352442
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.…
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…
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…
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,…
NASA Astrophysics Data System (ADS)
Kasparian, J.; Béjot, P.; Petrarca, M.; Hertz, S.; Lavorel, B.; Faucher, O.; Wolf, J.-P.
2013-03-01
The consideration of the higher-order Kerr effect (HOKE) drastically improves the quantitative agreement between measured and simulated harmonic yield as well as intensity and electron density in laser filaments generated by pulses below a few hundreds of fs. In longer pulses, the plasma defocusing plays a much more important role.
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. PMID:22386502
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 factual…
New explicit global asymptotic stability criteria for higher order difference equations
NASA Astrophysics Data System (ADS)
El-Morshedy, Hassan A.
2007-12-01
New explicit sufficient conditions for the asymptotic stability of the zero solution of higher order difference equations are obtained. These criteria can be applied to autonomous and nonautonomous equations. The celebrated Clark asymptotic stability criterion is improved. Also, applications to models from mathematical biology and macroeconomics are given.
Assessing Teachers' Pedagogical Knowledge in the Context of Teaching Higher-Order Thinking
ERIC Educational Resources Information Center
Zohar, Anat; Schwartzer, Noa
2005-01-01
This article reports the development and application of two instruments for assessing science teachers' pedagogical knowledge in the context of teaching higher-order thinking: a Likert-type research instrument, and an instrument that analyzes classroom observations. The rationale for developing these instruments and their main categories is…
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…
On Higher-order Corrections to Gyrokinetic Vlasov-Poisson Equations in the Long Wavelength Limit
W.W. Lee and R.A. Kolesnikov
2009-02-17
In this paper, we present a simple iterative procedure for obtaining the higher order E x B and dE/dt (polarization) drifts associated with the gyrokinetic Vlasov-Poisson equations in the long wavelength limit of k⊥ρi ~ o(ε) and k⊥L ~ o(1), where ρi is the ion gyroradius, L is the scale length of the background inhomogeneity and ε is a smallness parameter. It can be shown that these new higher order k⊥ρi terms, which are also related to the higher order perturbations of the electrostatic potential Φ, should have negligible effects on turbulent and neoclassical transport in tokamaks, regardless of the form of the background distribution and the amplitude of the perturbation. To address further the issue of a non-Maxwellian plasma, higher order finite Larmor radius terms in the gyrokinetic Poisson's equation have been studied and shown to be unimportant as well. On the other hand, the terms of o(k2⊥ρi2) ~ o(ε) and k⊥L ~ o(1) can indeed have impact on microturbulence, especially in the linear stage, such as those arising from the difference between the guiding center and the gyrocenter densities due to the presence of the background gradients. These results will be compared with a recent study questioning the validity of the commonly used gyrokinetic equations for long time simulations.
Explicit estimation of higher order modes in fission source distribution of Monte-Carlo calculation
Yamamoto, A.; Sakata, K.; Endo, T.
2013-07-01
Magnitude of higher order modes in fission source distribution of a multi-group Monte-Carlo calculation is estimated using the orthogonal property of forward and adjoint fission source distributions. Calculation capability of the forward and adjoint fission source distributions for fundamental and higher order modes are implemented in the AEGIS code, which is a two-dimensional transport code based on the method of characteristics. With the calculation results of the AEGIS code, magnitudes of the first to fifth higher order modes in fission source distribution obtained by the multi-group Monte-Carlo code GMVP are estimated. There are two contributions in the present study - (1) establishment of a surrogate model, which represents convergence of fission source distribution taking into account the inherent statistical 'noise' of higher order modes of Monte-Carlo calculations and (2) independent confirmation of the estimated dominance ratio in a Monte-Carlo calculation. The surrogate model would contribute to studies of the inter-cycle correlation and estimation of sufficient number of inactive/active cycles. (authors)
Inference of higher-order conifer relationships from a multi-locus plastid data set.
Technology Transfer Automated Retrieval System (TEKTRAN)
We reconstructed the broad backbone of conifer phylogeny from a survey of 15–17 plastid loci and associated noncoding regions from exemplar conifer species. Parsimony and likelihood analyses recover the same higher-order relationships, and we find strong support for most of the deep splits in conife...
An Examination of the Higher-Order Structure of Psychopathology and Its Relationship to Personality.
Uliaszek, Amanda A; Zinbarg, Richard E
2016-04-01
This study compared a series of higher-order models encompassing symptoms of both clinical and personality disorders. The final model was then correlated with a latent variable model of normal personality traits. A total of 420 undergraduates completed a battery of self-report symptom and personality questionnaires, with informant-reports and diagnostic interviews provided by overlapping subsamples. A three-level model with two factors at the highest level and four factors at the second level was the best fitting model. The higher-order internalizing and externalizing factors were then correlated with 30 latent personality facets. Results demonstrate an elevation on the neuroticism facets for the higher-order internalizing factor, along with low positive emotions, low actions, and low competence. The higher-order externalizing factor was negatively associated with most conscientiousness and agreeableness factors, while showing an elevation on excitement-seeking, impulsivity, and angry hostility. Future studies should replicate these models with the inclusion of more low base-rate disorders (i.e., psychosis). PMID:25893555
Variable-Length Computerized Adaptive Testing Using the Higher Order DINA Model
ERIC Educational Resources Information Center
Hsu, Chia-Ling; Wang, Wen-Chung
2015-01-01
Cognitive diagnosis models provide profile information about a set of latent binary attributes, whereas item response models yield a summary report on a latent continuous trait. To utilize the advantages of both models, higher order cognitive diagnosis models were developed in which information about both latent binary attributes and latent…
Helping Kids To Probe and Ponder: Integrating Higher Order Thinking into the General Curriculum.
ERIC Educational Resources Information Center
Stratton, Jean A.
This paper addresses issues in integrating higher order thinking into the general curriculum. Data are based on a series of telephone interviews conducted in April and May 1992 with six leading thinkers in educational reform. They included: (1) Michael Apple, John Bascom Professor of Curriculum, Instruction, and Educational Policy Studies at the…
An Initial Framework for the Language of Higher-Order Thinking Mathematics Practices
ERIC Educational Resources Information Center
Staples, Megan E.; Truxaw, Mary P.
2012-01-01
This article presents an examination of the language demands of cognitively demanding tasks and proposes an initial framework for the language demands of higher-order mathematics thinking practices. We articulate four categories for this framework: "language of generalisation," "language of comparison," "language of proportional reasoning," and…
Collapse for the higher-order nonlinear Schrödinger equation
Achilleos, V.; Diamantidis, S.; Frantzeskakis, D. J.; Horikis, T. P.; Karachalios, N. I.; Kevrekidis, P. G.
2016-02-01
We examine conditions for finite-time collapse of the solutions of the higher-order nonlinear Schr odinger (NLS) equation incorporating third-order dispersion, self-steepening, linear and nonlinear gain and loss, and Raman scattering; this is a system that appears in many physical contexts as a more realistic generalization of the integrable NLS. By using energy arguments, it is found that the collapse dynamics is chiefly controlled by the linear/nonlinear gain/loss strengths. We identify a critical value of the linear gain, separating the possible decay of solutions to the trivial zero-state, from collapse. The numerical simulations, performed for a wide class of initial data,more » are found to be in very good agreement with the analytical results, and reveal long-time stability properties of localized solutions. The role of the higher-order effects to the transient dynamics is also revealed in these simulations.« less
Spur-Reduced Digital Sinusoid Generation Using Higher-Order Phase Dithering
NASA Technical Reports Server (NTRS)
Flanagan, M.; Zimmerman, G.
1993-01-01
A higher-order phase dithering technique that reduces the complexity of digital sinusoid generation is presented and analyzed. M(sup th) order phase dithering denotes the addition of M independent, uniform variates to the sinusoid phase prior to word-length reduction. Spurious magnitudes due to quantization effects are accelerated from the usual -6 dBc per phase bit to -6(M + 1) dBc per phase bit, while the noise power increases linearly in M. For a given spurious specification, higher-order phase dithering permits the use of fewer phase bits than the non-dithered system, resulting in an exponential reduction in look-up table size, dramatically decreasing system complexity.
Influence of higher order modes on the beam stability in the high power superconducting proton linac
NASA Astrophysics Data System (ADS)
Schuh, Marcel; Gerigk, Frank; Tückmantel, Joachim; Welsch, Carsten P.
2011-05-01
Higher order modes (HOMs) can severely limit the operation of superconducting cavities in a linear accelerator with high beam current, high duty factor, and complex pulse structure. The full HOM spectrum has to be analyzed in order to identify potentially dangerous modes already during the design phase and to define their damping requirements. For this purpose a dedicated beam simulation code simulation of higher order mode dynamics (SMD) focused on beam-HOM interaction was developed, taking into account important effects like the HOM frequency spread, beam input jitter, different chopping patterns, as well as klystron and alignment errors. Here, SMD is used to investigate the influence of HOMs in detail in the superconducting proton linac at CERN and their potential to drive beam instabilities in the longitudinal and transverse plane.
A refined higher-order theory and its finite element method for thick laminated plates
NASA Astrophysics Data System (ADS)
Fu, Xiaohua; Chen, Haoran; Wang, Zhenming
1992-04-01
An improved higher-order theory developed to enhance the accuracy of the shear deformation theory of thick laminated plates is presented. The Legendre polynomials are introduced in the approximate displacement distributions across the plate thickness, and an FEM is suggested from the original equations. The accuracy of the present theory is examined by applying it to bending problems of laminate plates solved by Pagano. The results are compared with 3D elasticity solutions, the second order shear deformation theory, and some other higher-order shear deformation theory solutions. The present theory shows the deflections and stress more accurately than that obtained from previous works in the structural analysis of laminated plates with a small span with respect to thickness.
Finite time control for MIMO nonlinear system based on higher-order sliding mode.
Liu, Xiangjie; Han, Yaozhen
2014-11-01
Considering a class of MIMO uncertain nonlinear system, a novel finite time stable control algorithm is proposed based on higher-order sliding mode concept. The higher-order sliding mode control problem of MIMO nonlinear system is firstly transformed into finite time stability problem of multivariable system. Then continuous control law, which can guarantee finite time stabilization of nominal integral chain system, is employed. The second-order sliding mode is used to overcome the system uncertainties. High frequency chattering phenomenon of sliding mode is greatly weakened, and the arbitrarily fast convergence is reached. The finite time stability is proved based on the quadratic form Lyapunov function. Examples concerning the triple integral chain system with uncertainty and the hovercraft trajectory tracking are simulated respectively to verify the effectiveness and the robustness of the proposed algorithm. PMID:25277626
Coaxial higher-order mode damper employing a high-pass filter
Kang, Y.W.; Jiang, X.
1997-08-01
Two different types of coaxial higher-order mode (HOM) dampers have been investigated for the Advanced Photon Source (APS) storage ring cavities: e-probe dampers and h-loop dampers. Realization of the h-loop dampers has been difficult because the loop antenna couples not only to the HOMs but also to the accelerating mode and results in loss of Q at the fundamental frequency. Previously, a first-order fundamental rejection filter was tested with unsatisfactory rejection characteristics. This problem can be overcome by using a higher-order high-pass filter between the loop and the matched load. Prototype dampers have been fabricated and tested in a storage ring single-cell cavity and the damping characteristic was analyzed.
Generalized quantum kinetic expansion: Higher-order corrections to multichromophoric Förster theory
Wu, Jianlan Gong, Zhihao; Tang, Zhoufei
2015-08-21
For a general two-cluster energy transfer network, a new methodology of the generalized quantum kinetic expansion (GQKE) method is developed, which predicts an exact time-convolution equation for the cluster population evolution under the initial condition of the local cluster equilibrium state. The cluster-to-cluster rate kernel is expanded over the inter-cluster couplings. The lowest second-order GQKE rate recovers the multichromophoric Förster theory (MCFT) rate. The higher-order corrections to the MCFT rate are systematically included using the continued fraction resummation form, resulting in the resummed GQKE method. The reliability of the GQKE methodology is verified in two model systems, revealing the relevance of higher-order corrections.
NASA Astrophysics Data System (ADS)
He, Tian; Ye, Wu; Pan, Qiang; Liu, Xiandong
2016-02-01
One key aspect of local fault diagnosis is how to effectively extract abrupt features from the vibration signals. This paper proposes a method to automatically extract abrupt information based on singular value decomposition and higher-order statistics. In order to observe the distribution law of singular values, a numerical analysis to simulate the noise, periodic signal, abrupt signal and singular value distribution is conducted. Based on higher-order statistics and spectrum analysis, a method to automatically choose the upper and lower borders of the singular value interval reflecting the abrupt information is built. And the selected singular values derived from this method are used to reconstruct abrupt signals. It is proven that the method is able to obtain accurate results by processing the rub-impact fault signal measured from the experiments. The analytical and experimental results indicate that the proposed method is feasible for automatically extracting abrupt information caused by faults like the rotor-stator rub-impact.
NASA Astrophysics Data System (ADS)
Li, Jinsha; Li, Junmin
2016-07-01
In this paper, the adaptive fuzzy iterative learning control scheme is proposed for coordination problems of Mth order (M ≥ 2) distributed multi-agent systems. Every follower agent has a higher order integrator with unknown nonlinear dynamics and input disturbance. The dynamics of the leader are a higher order nonlinear systems and only available to a portion of the follower agents. With distributed initial state learning, the unified distributed protocols combined time-domain and iteration-domain adaptive laws guarantee that the follower agents track the leader uniformly on [0, T]. Then, the proposed algorithm extends to achieve the formation control. A numerical example and a multiple robotic system are provided to demonstrate the performance of the proposed approach.
Higher-dimensional thin-shell wormholes in third-order Lovelock gravity
NASA Astrophysics Data System (ADS)
Mehdizadeh, Mohammad Reza; Zangeneh, Mahdi Kord; Lobo, Francisco S. N.
2015-08-01
In this paper, we explore asymptotically flat charged thin-shell wormholes of third order Lovelock gravity in higher dimensions, taking into account the cut-and-paste technique. Using the generalized junction conditions, we determine the energy-momentum tensor of these solutions on the shell, and explore the issue of the energy conditions and the amount of normal matter that supports these thin-shell wormholes. Our analysis shows that for negative second-order and positive third-order Lovelock coefficients, there are thin-shell wormhole solutions that respect the weak energy condition. In this case, the amount of normal matter increases as the third-order Lovelock coefficient decreases. We also find novel solutions which possess specific regions where the energy conditions are satisfied for the case of a positive second-order and negative third-order Lovelock coefficients. Finally, a linear stability analysis in higher dimensions around the static solutions is carried out. Considering a specific cold equation of state, we find a wide range of stability regions.
NASA Astrophysics Data System (ADS)
Sabry-Rizk, Madiha; Zgallai, Walid; El-Khafif, Sahar; Carson, Ewart; Grattan, Kenneth T. V.
1998-10-01
The objective of this paper is to demonstrate how, in a few seconds, a relatively simple ECG monitor, PC and advanced signal processing algorithms could pinpoint microvolts - late potentials - result from an infarct zone in the heart and is used as an indicator in identifying patients prone to ventricular tachycardia which, if left untreated, leads to ventricular fibrillation. We will characterize recorded ECG data obtained from the standard three vector electrodes during exercise in terms of their higher-order statistical features. Essentially we use adaptive LMS- and Kalman-based second- and third-order Volterra filters to model the non- linear low-frequency P and T waves and motion artifacts which might overlap with the QRS complex and lead to false positive QRS detection. We will illustrate the effectiveness of this new approach by mapping out bispectral regions with a strong bicoherence manifestation and showing their corresponding temporal/spatial origins. Furthermore, we will present a few examples of our own application of these non-invasive techniques to illustrate what we see as their promise for analysis of heart abnormality.
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.
Multifunctional diffractive optical elements for the generation of higher order Bessel-like-beams
NASA Astrophysics Data System (ADS)
Vijayakumar, A.; Bhattacharya, Shanti
2015-01-01
Higher Order Bessel Beams (HOBBs) have many useful applications in optical trapping experiments. The generation of HOBBs is achieved by illuminating an axicon by a Laguerre-Gaussian beam generated by a spiral phase plate. It can also be generated by a Holographic Optical Element (HOE) containing the functions of the Spiral Phase Plate (SPP) and an axicon. However the HOBB's large focal depth reduces the intensity at each plane. In this paper, we propose a multifunctional Diffractive Optical Element (DOE) containing the functions of a SPP, axicon and a Fresnel Zone Lens (FZL) to generate higher efficiency higher order Bessel-like-beams with a reduced focal depth. The functions of a SPP and a FZL were combined by shifting the location of zones of FZL in a spiral fashion. The resulting element is combined with an axicon by modulo-2π phase addition technique. The final composite element contains the functions of SPP, FZL and axicon. The elements were designed with different topological charges and fabricated using electron beam direct writing. The elements were tested and the generation of a higher order Bessel-like-beams is confirmed. Besides, the elements also generated high quality donut beams at two planes equidistant from the focal plane of the FZL.
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.
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.
Effect of wavefront optimized LASIK on higher order aberrations in myopic patients
Khan, Muhammad Saim; Humayun, Sadia; Fawad, Aisha; Ishaq, Mazhar; Arzoo, Sabahat; Mashhadi, Fawad
2015-01-01
Objective: To determine mean change induced in root mean square value of higher order aberrations in myopic patients undergoing wavefront optimized laser assisted in situ keratomileusis. Methods: This quasi experimental study was conducted at Armed Forces Institute of Ophthalmology, Rawalpindi, Pakistan from Jan 2014 to Dec 2014. Sixty eyes of 35 myopic patients were included in the study. All patients underwent wavefront optimized (WFO) laser assisted in situ keratomileusis (LASIK) using femtosecond laser (FM 200Wavelight technologies) and excimer laser (Ew 500Wavelight technologies). Higher order aberrations (HOAs) were measured with aberrometer (Wavelight allegro analyzer version 1073) during preoperative assessment and one month after surgery. Results: All 35 patients ranged from 20 to 32 years with a mean age of 24 ± 3.41 years. Refractive error ranged from -1.00 to -9.50 DS with a mean spherical equivalent (SE) of -3.73 ± 1.95 before surgery and - 0.36 ± 1.50DS one month after LASIK. Uncorrected visual acuity (UCVA) was improved to 0.00 or better in all 60 eyes. An increase of 1.56 fold was observed in RMS of total HOAs. Among the HOAs, a statistically significant positive correlation was observed between spherical aberrations (4th order aberration) and preoperative spherical equivalent. Conclusion: In spite of excellent improvement in refractive error, significant amount of higher order aberrations were induced after WFO LASIK. PMID:26649018
NASA Astrophysics Data System (ADS)
Luo, Chun-Ling; Cheng, Jing; Chen, Ai-Xi; Liu, Zhi-Min
2015-10-01
We show that the resolution of the computational ghost imaging (CGI) system through atmospheric turbulence can be significantly improved by modulating a coherent source with high-order cosh-Gaussian functions. The analytical formula for the CGI system with a higher-order cosh-Gaussian source in turbulent atmosphere is derived and can be viewed as the original object convoluted a point-spread function (PSF). The imaging quality is mainly determined by the size of the PSF, which is closely related to the source parameters of the higher-order cosh-Gaussian beam, the turbulent strength and the propagation distance. Numerical examples are given to clearly see the effects of the above system parameters on the PSF and the quality of the CGI system. Compared with the widely used Gaussian source, it is found that the resolution of CGI can be obviously enhanced by properly adjusting the parameters of the higher-order cosh-Gaussian sources. Thus this kind of shaped source can be used to improve the imaging resolution and may be helpful to the CGI real applications.
Higher-order neural network software for distortion invariant object recognition
NASA Technical Reports Server (NTRS)
Reid, Max B.; Spirkovska, Lilly
1991-01-01
The state-of-the-art in pattern recognition for such applications as automatic target recognition and industrial robotic vision relies on digital image processing. We present a higher-order neural network model and software which performs the complete feature extraction-pattern classification paradigm required for automatic pattern recognition. Using a third-order neural network, we demonstrate complete, 100 percent accurate invariance to distortions of scale, position, and in-plate rotation. In a higher-order neural network, feature extraction is built into the network, and does not have to be learned. Only the relatively simple classification step must be learned. This is key to achieving very rapid training. The training set is much smaller than with standard neural network software because the higher-order network only has to be shown one view of each object to be learned, not every possible view. The software and graphical user interface run on any Sun workstation. Results of the use of the neural software in autonomous robotic vision systems are presented. Such a system could have extensive application in robotic manufacturing.
Higher-order statistics correlation stacking for DC electrical data in the wavelet domain
NASA Astrophysics Data System (ADS)
Li, Jinghe; He, Zhanxiang; Liu, Qing Huo
2013-12-01
DC (direct current) electrical and shallow seismic methods are indispensable to the near surface geophysical exploration, but the near surface areas are very difficult environments for any geophysical exploration due to the random noise caused by near surface inhomogeneities. As a new algorithm based on higher-order statistics theory, the higher-order correlation stacking algorithm for seismic data smoothing in the wavelet domain has been developed and applied efficiently to filter some correlation noise that the conventional second-order correlation stacking could not inhibit. In this paper, this higher-order statistics correlation stacking technology is presented for DC electrical data in wavelet domain. Taking into account the single section and multiple section data, we present two new formulations of correlation stacking for DC electrical data. Synthetic examples with Gaussian noise are designed to analyze the overall efficiency of the new algorithm and to determine its efficacy. Meanwhile, comparison with the traditional least-squares optimization inversion method for field examples from electrical imaging surveys and time-domain IP measurement in China shows its significant advantages. The quality of the new algorithm also has been assessed by physical simulation experiments. This new technology in DC electrical exploration measurements provides a new application in engineering and mining investigation.
Symbolic Algebra Development for Higher-Order Electron Propagator Formulation and Implementation.
Tamayo-Mendoza, Teresa; Flores-Moreno, Roberto
2014-06-10
Through the use of symbolic algebra, implemented in a program, the algebraic expression of the elements of the self-energy matrix for the electron propagator to different orders were obtained. In addition, a module for the software package Lowdin was automatically generated. Second- and third-order electron propagator results have been calculated to test the correct operation of the program. It was found that the Fortran 90 modules obtained automatically with our algorithm succeeded in calculating ionization energies with the second- and third-order electron propagator in the diagonal approximation. The strategy for the development of this symbolic algebra program is described in detail. This represents a solid starting point for the automatic derivation and implementation of higher-order electron propagator methods. PMID:26580756
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. PMID:23889011
Budyak, Ivan L; Doyle, Brandon L; Weiss, William F
2015-04-01
Robust higher order structure (HOS) characterization capability and strategy are critical throughout biopharmaceutical development from initial candidate selection and formulation screening to process optimization and manufacturing. This case study describes the utility of several orthogonal HOS methods as investigational tools during purification process development. An atypically high level of residual detergent in a development drug substance batch of a therapeutic monoclonal antibody triggered a root cause investigation. Several orthogonal biophysical techniques were used to uncover and characterize a specific interaction between the detergent and the antibody. Isothermal titration calorimetry (ITC) was used to quantify the molar ratio and affinity of the binding event, and circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC) were used to evaluate corresponding impacts on secondary/tertiary structure and thermal stability, respectively. As detergents are used routinely in biopharmaceutical processing, this case study highlights the value and power of HOS data in informing technical investigations and underlines the importance of HOS characterization as a component of overall biopharmaceutical analytical control strategy. PMID:25545760
Higher-order contributions to transport coefficients in two-temperature hydrogen thermal plasma
Sharma, Rohit; Singh, Gurpreet; Singh, Kuldip
2011-06-15
Within the framework of Chapman-Enskog method, electron transport properties and their higher-order contributions have been studied in temperature range 5000-40 000 K at different pressures for hydrogen thermal plasma in local thermodynamic equilibrium (LTE) and non-local thermodynamic equilibrium (NLTE) regimes. Two cases of thermal plasma have been considered: (i) Ground state (GS) plasma in which all atomic hydrogen has been assumed to be in ground state and (ii) the excited state (ES) plasma in which hydrogen atoms are distributed in various possible electronically excited states (EES). The plasma composition is calculated by modified Saha equation of van de Sanden et al. The influence of non-equilibrium parameter {theta} (=T{sub e}/T{sub h}) on these properties has been examined in both the cases. It has been observed that both EES and {theta} modify the plasma composition and consequently affect the electron transport properties (viz., electron thermal conductivity, electrical conductivity, thermal diffusion and thermal diffusion ratio). It is shown that non-equilibrium parameter {theta} has meager effect on the higher-order convergence in comparison to EES. The unique behaviour observed for third-order contribution to these transport properties in GS plasma for small values of {theta} could be explained only when EES are taken into account. It is noted that EES show their influence on higher-orders to a considerable extent even when e-H(n) cross-sections are replaced by the ground state ones. Thus electron transport coefficients and their higher-order contributions are affected significantly due to inclusion of EES in LTE and NLTE plasmas.
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
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
Higher Order, Hybrid BEM/FEM Methods Applied to Antenna Modeling
NASA Technical Reports Server (NTRS)
Fink, P. W.; Wilton, D. R.; Dobbins, J. A.
2002-01-01
In this presentation, the authors address topics relevant to higher order modeling using hybrid BEM/FEM formulations. The first of these is the limitation on convergence rates imposed by geometric modeling errors in the analysis of scattering by a dielectric sphere. The second topic is the application of an Incomplete LU Threshold (ILUT) preconditioner to solve the linear system resulting from the BEM/FEM formulation. The final tOpic is the application of the higher order BEM/FEM formulation to antenna modeling problems. The authors have previously presented work on the benefits of higher order modeling. To achieve these benefits, special attention is required in the integration of singular and near-singular terms arising in the surface integral equation. Several methods for handling these terms have been presented. It is also well known that achieving he high rates of convergence afforded by higher order bases may als'o require the employment of higher order geometry models. A number of publications have described the use of quadratic elements to model curved surfaces. The authors have shown in an EFIE formulation, applied to scattering by a PEC .sphere, that quadratic order elements may be insufficient to prevent the domination of modeling errors. In fact, on a PEC sphere with radius r = 0.58 Lambda(sub 0), a quartic order geometry representation was required to obtain a convergence benefi.t from quadratic bases when compared to the convergence rate achieved with linear bases. Initial trials indicate that, for a dielectric sphere of the same radius, - requirements on the geometry model are not as severe as for the PEC sphere. The authors will present convergence results for higher order bases as a function of the geometry model order in the hybrid BEM/FEM formulation applied to dielectric spheres. It is well known that the system matrix resulting from the hybrid BEM/FEM formulation is ill -conditioned. For many real applications, a good preconditioner is required
A family of solutions of a higher order PVI equation near a regular singularity
NASA Astrophysics Data System (ADS)
Shimomura, Shun
2006-09-01
Restriction of the N-dimensional Garnier system to a complex line yields a system of second-order nonlinear differential equations, which may be regarded as a higher order version of the sixth Painlevé equation. Near a regular singularity of the system, we present a 2N-parameter family of solutions expanded into convergent series. These solutions are constructed by iteration, and their convergence is proved by using a kind of majorant series. For simplicity, we describe the proof in the case N = 2.
Generation of arbitrary cylindrical vector beams on the higher order Poincaré sphere.
Chen, Shizhen; Zhou, Xinxing; Liu, Yachao; Ling, Xiaohui; Luo, Hailu; Wen, Shuangchun
2014-09-15
We propose and experimentally demonstrate a novel interferometric approach to generate arbitrary cylindrical vector beams on the higher order Poincaré sphere (HOPS). Our scheme is implemented by collinear superposition of two orthogonal circular polarizations with opposite topological charges. By modifying the amplitude and phase factors of the two beams, respectively, any desired vector beams on the HOPS with high tunability can be acquired. Our research provides a convenient way to evolve the polarization states in any path on the high order Poincaré sphere. PMID:26466249
Strong higher-order resonant contributions to x-ray line polarization in hot plasmas
NASA Astrophysics Data System (ADS)
Shah, Chintan; Amaro, Pedro; Steinbrügge, Rene; Beilmann, Christian; Bernitt, Sven; Fritzsche, Stephan; Surzhykov, Andrey; Crespo López-Urrutia, José R.; Tashenov, Stanislav
2016-06-01
We studied angular distributions of x rays emitted in resonant recombination of highly charged iron and krypton ions, resolving dielectronic, trielectronic, and quadruelectronic channels. A tunable electron beam drove these processes, inducing x rays registered by two detectors mounted along and perpendicular to the beam axis. The measured emission asymmetries comprehensively benchmarked full-order atomic calculations. We conclude that accurate polarization diagnostics of hot plasmas can only be obtained under the premise of inclusion of higher-order processes that were neglected in earlier work.
Strong higher-order resonant contributions to x-ray line polarization in hot plasmas.
Shah, Chintan; Amaro, Pedro; Steinbrügge, Rene; Beilmann, Christian; Bernitt, Sven; Fritzsche, Stephan; Surzhykov, Andrey; Crespo López-Urrutia, José R; Tashenov, Stanislav
2016-06-01
We studied angular distributions of x rays emitted in resonant recombination of highly charged iron and krypton ions, resolving dielectronic, trielectronic, and quadruelectronic channels. A tunable electron beam drove these processes, inducing x rays registered by two detectors mounted along and perpendicular to the beam axis. The measured emission asymmetries comprehensively benchmarked full-order atomic calculations. We conclude that accurate polarization diagnostics of hot plasmas can only be obtained under the premise of inclusion of higher-order processes that were neglected in earlier work. PMID:27415199
Quantum Enhancement of Higher-Order Phononlike Excitations of a Bose-Einstein Condensate
Rowen, E. E.; Bar-Gill, N.; Davidson, N.
2008-07-04
In a Bose-Einstein condensate, the excitation of a Bogoliubov phonon with low momentum (e.g., by a two-photon Bragg process) is strongly suppressed due to destructive interference between two indistinguishable excitation pathways. Here we show that scattering of this sound excitation into a double-momentum mode is strongly enhanced due to constructive interference. This enhancement yields an inherent amplification of second-order sound excitations of the condensate, as we confirm experimentally. We further show that due to parity considerations, this effect is extended to higher-order excitations.
Quantum Effects in Higher-Order Correlators of a Quantum-Dot Spin Qubit
NASA Astrophysics Data System (ADS)
Bechtold, A.; Li, F.; Müller, K.; Simmet, T.; Ardelt, P.-L.; Finley, J. J.; Sinitsyn, N. A.
2016-07-01
We measure time correlators of a spin qubit in an optically active quantum dot beyond the second order. Such higher-order correlators are shown to be directly sensitive to pure quantum effects that cannot be explained within the classical framework. They allow direct determination of ensemble and quantum dephasing times, T2* and T2, using only repeated projective measurements and without the need for coherent spin control. Our method enables studies of purely quantum behavior in solid state systems, including tests of the Leggett-Garg type of inequalities that rule out local hidden variable interpretation of the quantum-dot spin dynamics.
Quantum Effects in Higher-Order Correlators of a Quantum-Dot Spin Qubit.
Bechtold, A; Li, F; Müller, K; Simmet, T; Ardelt, P-L; Finley, J J; Sinitsyn, N A
2016-07-01
We measure time correlators of a spin qubit in an optically active quantum dot beyond the second order. Such higher-order correlators are shown to be directly sensitive to pure quantum effects that cannot be explained within the classical framework. They allow direct determination of ensemble and quantum dephasing times, T_{2}^{*} and T_{2}, using only repeated projective measurements and without the need for coherent spin control. Our method enables studies of purely quantum behavior in solid state systems, including tests of the Leggett-Garg type of inequalities that rule out local hidden variable interpretation of the quantum-dot spin dynamics. PMID:27447523
Reproduction of a higher-order circular harmonic field using a linear array of loudspeakers.
Lee, Jung-Min; Choi, Jung-Woo; Kim, Yang-Hann
2015-03-01
This paper presents a direct formula for reproducing a sound field consisting of higher-order circular harmonics with polar phase variation. Sound fields with phase variation can be used for synthesizing various spatial attributes, such as the perceived width or the location of a virtual sound source. To reproduce such a sound field using a linear loudspeaker array, the driving function of the array is derived in the format of an integral formula. The proposed function shows fewer reproduction errors than a conventional formula focused on magnitude variations. In addition, analysis of the sweet spot reveals that its shape can be asymmetric, depending on the order of harmonics. PMID:25951623
Controlled generation of higher-order Poincaré sphere beams from a laser
NASA Astrophysics Data System (ADS)
Naidoo, Darryl; Roux, Filippus S.; Dudley, Angela; Litvin, Igor; Piccirillo, Bruno; Marrucci, Lorenzo; Forbes, Andrew
2016-05-01
The angular momentum of light can be described by positions on a higher-order Poincaré sphere, where superpositions of spin and orbital angular momentum states give rise to laser beams that have many applications, from microscopy to materials processing. Many techniques exist to create such beams but none so far allow their creation at the source. Here we report on a new class of laser that is able to generate all states on the higher-order Poincaré sphere. We exploit geometric phase control inside a laser cavity to map polarization to orbital angular momentum, demonstrating that the orbital angular momentum degeneracy of a standard laser cavity may be broken, producing pure orbital angular momentum beams, and that generalized vector vortex beams may be created with high purity at the source. This work paves the way to new lasers for structured light based on intracavity geometric phase control.
Novel asymmetric representation method for solving the higher-order Ginzburg-Landau equation
NASA Astrophysics Data System (ADS)
Wong, Pring; Pang, Lihui; Wu, Ye; Lei, Ming; Liu, Wenjun
2016-04-01
In ultrafast optics, optical pulses are generated to be of shorter pulse duration, which has enormous significance to industrial applications and scientific research. The ultrashort pulse evolution in fiber lasers can be described by the higher-order Ginzburg-Landau (GL) equation. However, analytic soliton solutions for this equation have not been obtained by use of existing methods. In this paper, a novel method is proposed to deal with this equation. The analytic soliton solution is obtained for the first time, and is proved to be stable against amplitude perturbations. Through the split-step Fourier method, the bright soliton solution is studied numerically. The analytic results here may extend the integrable methods, and could be used to study soliton dynamics for some equations in other disciplines. It may also provide the other way to obtain two-soliton solutions for higher-order GL equations.
Predicting Hyper-Chaotic Time Series Using Adaptive Higher-Order Nonlinear Filter
NASA Astrophysics Data System (ADS)
Zhang, Jia-Shu; Xiao, Xian-Ci
2001-03-01
A newly proposed method, i.e. the adaptive higher-order nonlinear finite impulse response (HONFIR) filter based on higher-order sparse Volterra series expansions, is introduced to predict hyper-chaotic time series. The effectiveness of using the adaptive HONFIR filter for making one-step and multi-step predictions is tested based on very few data points by computer-generated hyper-chaotic time series including the Mackey-Glass equation and four-dimensional nonlinear dynamical system. A comparison is made with some neural networks for predicting the Mackey-Glass hyper-chaotic time series. Numerical simulation results show that the adaptive HONFIR filter proposed here is a very powerful tool for making prediction of hyper-chaotic time series.
The post-mitotic state in neurons correlates with a stable nuclear higher-order structure.
Aranda-Anzaldo, Armando
2012-03-01
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
Rayleigh scattering as a probe of higher-order mode propagation in an optical nanofiber
NASA Astrophysics Data System (ADS)
Fatemi, Fredrik K.; Hoffman, Jonathan E.; Beadie, Guy; Rolston, Steven L.; Orozco, Luis A.
2015-05-01
Optical nanofibers can have large evanescent fields that create strong interactions with atoms. To increase the complexity of the potential landscape, recent studies have explored the use of higher-order modes. However, with several propagating modes in the nanofiber, the challenge remains of controlling the field distribution on the nanofiber waist. Here, we describe imaging Rayleigh scattered light to analyze the spatial evolution of the propagating fields throughout the entire nanofiber, including the transition from core-cladding guidance to cladding-air guidance. By measuring local beat lengths between higher-order modes in situ, we identify and systematically control the modal composition. These measurements also provide a non-destructive tool for determining variations in the waist radius to below 3 nm using entirely optical means. Funded by ONR, the ARO Atomtronics MURI, DARPA, and the NSF through the PFC at JQI.
Novel asymmetric representation method for solving the higher-order Ginzburg-Landau equation
Wong, Pring; Pang, Lihui; Wu, Ye; Lei, Ming; Liu, Wenjun
2016-01-01
In ultrafast optics, optical pulses are generated to be of shorter pulse duration, which has enormous significance to industrial applications and scientific research. The ultrashort pulse evolution in fiber lasers can be described by the higher-order Ginzburg-Landau (GL) equation. However, analytic soliton solutions for this equation have not been obtained by use of existing methods. In this paper, a novel method is proposed to deal with this equation. The analytic soliton solution is obtained for the first time, and is proved to be stable against amplitude perturbations. Through the split-step Fourier method, the bright soliton solution is studied numerically. The analytic results here may extend the integrable methods, and could be used to study soliton dynamics for some equations in other disciplines. It may also provide the other way to obtain two-soliton solutions for higher-order GL equations. PMID:27086841
The dynamin middle domain is critical for tetramerization and higher-order self-assembly
Ramachandran, Rajesh; Surka, Mark; Chappie, Joshua S; Fowler, Douglas M; Foss, Ted R; Song, Byeong Doo; Schmid, Sandra L
2007-01-01
The large multidomain GTPase dynamin self-assembles around the necks of deeply invaginated coated pits at the plasma membrane and catalyzes vesicle scission by mechanisms that are not yet completely understood. Although a structural role for the ‘middle' domain in dynamin function has been suggested, it has not been experimentally established. Furthermore, it is not clear whether this putative function pertains to dynamin structure in the unassembled state or to its higher-order self-assembly or both. Here, we demonstrate that two mutations in this domain, R361S and R399A, disrupt the tetrameric structure of dynamin in the unassembled state and impair its ability to stably bind to and nucleate higher-order self-assembly on membranes. Consequently, these mutations also impair dynamin's assembly-dependent stimulated GTPase activity. PMID:17170701
The dynamin middle domain is critical for tetramerization and higher-order self-assembly.
Ramachandran, Rajesh; Surka, Mark; Chappie, Joshua S; Fowler, Douglas M; Foss, Ted R; Song, Byeong Doo; Schmid, Sandra L
2007-01-24
The large multidomain GTPase dynamin self-assembles around the necks of deeply invaginated coated pits at the plasma membrane and catalyzes vesicle scission by mechanisms that are not yet completely understood. Although a structural role for the 'middle' domain in dynamin function has been suggested, it has not been experimentally established. Furthermore, it is not clear whether this putative function pertains to dynamin structure in the unassembled state or to its higher-order self-assembly or both. Here, we demonstrate that two mutations in this domain, R361S and R399A, disrupt the tetrameric structure of dynamin in the unassembled state and impair its ability to stably bind to and nucleate higher-order self-assembly on membranes. Consequently, these mutations also impair dynamin's assembly-dependent stimulated GTPase activity. PMID:17170701
Acoustic properties of multiple cavity resonance liner for absorbing higher-order duct modes.
Zhou, Di; Wang, Xiaoyu; Jing, Xiaodong; Sun, Xiaofeng
2016-08-01
This paper describes analytical and experimental studies conducted to investigate the acoustic properties of axially non-uniform multiple cavity resonance liner for absorbing higher-order duct modes. A three-dimensional analytical model is proposed based upon transfer element method. The model is assessed by making a comparison with results of a liner performance experiment concerning higher-order modes propagation, and the agreement is good. According to the present results, it is found that the performance of multiple cavity resonance liner is related to the incident sound waves. Moreover, an analysis of the corresponding response of liner perforated panel-cavity system is performed, in which the features of resonance frequency and dissipation of the system under grazing or oblique incidence condition are revealed. The conclusions can be extended to typical non-locally reacting liners with single large back-cavity, and it would be beneficial for future non-locally reacting liner design to some extent. PMID:27586753
NASA Astrophysics Data System (ADS)
Gill, Tarsem Singh; Kaur, Ravinder; Mahajan, Ranju
2010-09-01
This paper presents an analysis of self-consistent, steady-state, theoretical model, which explains the ring formation in a Gaussian electromagnetic beam propagating in a magnetoplasma, characterized by relativistic nonlinearity. Higher order terms (up to r4) in the expansion of the dielectric function and the eikonal have been taken into account. The condition for the formation of a dark and bright ring derived earlier by Misra and Mishra [J. Plasma Phys. 75, 769 (2009)] has been used to study focusing/defocusing of the beam. It is seen that inclusion of higher order terms does significantly affect the dependence of the beam width on the distance of propagation. Further, the effect of the magnetic field and the nature of nonlinearity on the ring formation and self-focusing of the beam have been explored.
Higher order direct model reference adaptive control with generic uniform ultimate boundedness
NASA Astrophysics Data System (ADS)
Maity, Arnab; Höcht, Leonhard; Holzapfel, Florian
2015-10-01
This paper proposes a new higher order model reference adaptive control (HO-MRAC) approach following direct adaptive control philosophy, which estimates unknown time-varying parameters. This approach leads to a Lyapunov based conventional MRAC update law, augmented by an observer type parameter predictor dynamics. The predictor dynamics are composed of a stable known part, a feedback of the parameter error and unknown higher order parameters, which are updated using a Lyapunov based adaptive design. So, this HO-MRAC can cope with rapidly changing parameters, due to estimation of their time derivatives. Moreover, for stability analysis, a Lyapunov based generic ultimate boundedness theorem is presented, which allows for a computation of separate bounds for each state vector partition. Furthermore, this theorem formulates the explicit specification of transient and ultimate bounds, reaching time on the ultimate bounds and a set of admissible initial conditions. Two challenging illustrative examples demonstrate the effectiveness of the proposed approach.
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)
Higher-Order Laguerre-Gauss Mode Generation and Interferometry for Gravitational Wave Detectors
NASA Astrophysics Data System (ADS)
Granata, M.; Buy, C.; Ward, R.; Barsuglia, M.
2010-12-01
We report on the first experimental demonstration of higher-order Laguerre-Gauss (LGpℓ) mode generation and interferometry using a method scalable to the requirements of gravitational wave (GW) detection. GW detectors which use higher-order LGpℓ modes will be less susceptible to mirror thermal noise, which is expected to limit the sensitivity of all currently planned terrestrial detectors. We used a diffractive optic and a mode-cleaner cavity to convert a fundamental LG00 Gaussian beam into an LG33 mode with a purity of 98%. The ratio between the power of the LG00 mode of our laser and the power of the LG33 transmitted by the cavity was 36%. By measuring the transmission of our setup using the LG00, we inferred that the conversion efficiency specific to the LG33 mode was 49%. We illuminated a Michelson interferometer with the LG33 beam and achieved a visibility of 97%.
Novel asymmetric representation method for solving the higher-order Ginzburg-Landau equation.
Wong, Pring; Pang, Lihui; Wu, Ye; Lei, Ming; Liu, Wenjun
2016-01-01
In ultrafast optics, optical pulses are generated to be of shorter pulse duration, which has enormous significance to industrial applications and scientific research. The ultrashort pulse evolution in fiber lasers can be described by the higher-order Ginzburg-Landau (GL) equation. However, analytic soliton solutions for this equation have not been obtained by use of existing methods. In this paper, a novel method is proposed to deal with this equation. The analytic soliton solution is obtained for the first time, and is proved to be stable against amplitude perturbations. Through the split-step Fourier method, the bright soliton solution is studied numerically. The analytic results here may extend the integrable methods, and could be used to study soliton dynamics for some equations in other disciplines. It may also provide the other way to obtain two-soliton solutions for higher-order GL equations. PMID:27086841
Higher-order laser beam scintillation in weakly turbulent marine atmospheric medium.
Baykal, Yahya
2016-04-01
The atmosphere above the sea or ocean, known as the marine atmosphere, affects optical waves propagating through it in a different manner than the atmosphere above land. Like other system design parameters, intensity fluctuations of laser light propagating in marine atmosphere, quantified by the scintillation index, also show different variations. The on-axis scintillations of higher-order laser beams are formulated and evaluated when such excitations are employed in a weakly turbulent marine atmospheric medium. Variations of the scintillation index with respect to the changes in the Gaussian beam size of the higher-order mode, link length, wavelength, and structure constant are reported. Our results can be used in the design of an optical wireless communication link design operating in marine atmospheres. PMID:27140788
Analysis of Higher Order Modes Damping Techniques in 9 Cell Cavity with Modified Drift Tubes
NASA Astrophysics Data System (ADS)
Shashkov, Ya. V.; Mitrofanov, A. A.; Sobenin, N. P.; Zvyagintsev, V. L.
Electrodynamic characteristics (EDC) of higher order modes (HOM) were calculated for a superconducting 9-cell accelerating cavity of eLinac accelerator with operating frequency of 1300 MHz. Several HOM damping techniques including damping with grooved, fluted and ridged beam pipes were analyzed and compared. The influence of the parameters of the drift tube on the HOM damping and on the parameters of the fundamental wave was analyzed.
The relation between tympanic membrane higher order modes and standing waves
NASA Astrophysics Data System (ADS)
Allen, Jont B.
2015-12-01
Here we address the question of the specific relation between Tympanic Membrane (TM) higher order modes, and the existence of standing waves. These questions relate to the nature of the middle ear (ME) as a cascade of transmission lines, and what happens when the matching goes from nearly perfect, when the normal cochlear is the TM load, to totally out of balance, due to either ME or cochlear pathology. This is important for the diagnoses of a pathology given the ME reflectance.
Yamaguchi, Takefumi; Negishi, Kazuno; Ohnuma, Kazuhiko; Tsubota, Kazuo
2011-01-01
Background The purpose of this study was to evaluate the correlation between contrast sensitivity and calculated higher-order aberrations based on individual natural pupil diameter after cataract surgery. Methods This prospective study included 120 eyes from 92 patients who were randomized to receive one of four lenses, including three aspheric lenses (Acrysof SN60WF, Tecnis ZA9000, and Hoya Py60AD) and one spherical lens (Acrysof SN60AT). Contrast sensitivity, higher-order aberrations of the whole eye, and pupil diameter under photopic and mesopic conditions were measured 1 month postoperatively. Higher-order aberrations were decomposed into Zernike coefficients, calculated according to individual pupil diameter. The correlation between higher-order aberrations and contrast sensitivity was evaluated. Results There were no significant differences in contrast sensitivity function between the four types of lenses under photopic conditions. However, the contrast sensitivity function and area under log contrast sensitivity function in the aspheric lenses were significantly better than in the spherical lens under mesopic conditions. Under mesopic conditions, spherical aberration in eyes with aspheric lenses was significantly lower than in eyes with spherical lenses (P < 0.05). Under photopic conditions, coma aberration had a significant negative correlation with contrast sensitivity at 12 cycles/degree. Under mesopic conditions, spherical aberration had a significant negative correlation with contrast sensitivity at 3, 6, and 12 cycles/degree with glare, and with contrast sensitivity at 6 and 18 cycles/degree without glare. Conclusion In terms of influence on visual function, coma aberration may be more significant under photopic conditions and spherical aberration under mesopic conditions. PMID:22205829
Conical emission from laser filaments and higher-order Kerr effect in air.
Béjot, P; Kasparian, J
2011-12-15
We numerically investigate the conical emission (CE) from ultrashort laser filaments, both considering and disregarding the higher-order Kerr effect (HOKE). While the consideration of HOKE has almost no influence on the predicted CE from collimated beams, differences arise for tightly focused beams. This difference is attributed to the different relative contributions of the nonlinear focus and of the modulational instability over the whole filament length. PMID:22179892
Waist location and Rayleigh range for higher-order mode laser beams
Luxon, J.T.; Parker, D.E.; Karkheck, J.
1984-07-01
Self has presented simple equations for Gaussian-mode laser beams for calculating focused waist location and beam waist magnification in terms of the Rayleigh range. Since the Rayleigh range is a purely geometrical quantity. Self's equations can also be applied to higher-order mode beams. A convenient form of the Rayleigh range for Hermite-Gaussian modes is presented along with representative results for Co/sub 2/ laser industrial processing facilities.
Higher order modes of a 3rd harmonic cavity with an increased end-cup iris
T. Khabibouline; N. Solyak; R. Wanzenberg
2003-05-19
The cavity design for a 3rd harmonic cavity for the TTF 2 photoinjector has been revised to increase the coupling between the main coupler and the cavity cells. The iris radius of the end cup of the cavity has been increased to accomplish a better coupling. The basic rf-parameters and the higher order modes of the modified design are summarized in this report.
Higher-order modulation formats for spectral-efficient high-speed metro systems
NASA Astrophysics Data System (ADS)
Freund, R.; Nölle, M.; Seimetz, M.; Hilt, J.; Fischer, J.; Ludwig, R.; Schubert, C.; Bach, H.-G.; Velthaus, K.-O.; Schell, M.
2011-01-01
Worldwide, higher-order modulation formats are intensively investigated to further increase the spectral efficiency for building the next generation of high-speed metro systems. IQ-modulators, coherent receivers and electronic equalizers are hereby discussed as key devices. We report on system design issues as well as on HHI's latest achievements in developing InP based high-speed modulators and coherent receiver frontends.
Multicriteria Decision Making Method Based on the Higher Order Hesitant Fuzzy Soft Set
Farhadinia, B.
2014-01-01
The main goal of this contribution is to introduce the concept of higher order hesitant fuzzy soft set as an extension of fuzzy soft set that encompasses most of the existing extensions of fuzzy soft set as special cases. Furthermore, this new concept provides us with a method for dealing with multicriteria fuzzy decision making problems which are difficult to explain in other existing extensions of fuzzy soft set theory, especially when problems involve parameters with different-dimensional levels. PMID:27437496
The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry
Carbone, Ludovico; Fulda, Paul; Bond, Charlotte; Brueckner, Frank; Brown, Daniel; Wang, Mengyao; Lodhia, Deepali; Palmer, Rebecca; Freise, Andreas
2013-01-01
Thermal noise in high-reflectivity mirrors is a major impediment for several types of high-precision interferometric experiments that aim to reach the standard quantum limit or to cool mechanical systems to their quantum ground state. This is for example the case of future gravitational wave observatories, whose sensitivity to gravitational wave signals is expected to be limited in the most sensitive frequency band, by atomic vibration of their mirror masses. One promising approach being pursued to overcome this limitation is to employ higher-order Laguerre-Gauss (LG) optical beams in place of the conventionally used fundamental mode. Owing to their more homogeneous light intensity distribution these beams average more effectively over the thermally driven fluctuations of the mirror surface, which in turn reduces the uncertainty in the mirror position sensed by the laser light. We demonstrate a promising method to generate higher-order LG beams by shaping a fundamental Gaussian beam with the help of diffractive optical elements. We show that with conventional sensing and control techniques that are known for stabilizing fundamental laser beams, higher-order LG modes can be purified and stabilized just as well at a comparably high level. A set of diagnostic tools allows us to control and tailor the properties of generated LG beams. This enabled us to produce an LG beam with the highest purity reported to date. The demonstrated compatibility of higher-order LG modes with standard interferometry techniques and with the use of standard spherical optics makes them an ideal candidate for application in a future generation of high-precision interferometry. PMID:23962813
Blowup results for the KGS system with higher order Yukawa coupling
Shi, Qi-Hong; Li, Wan-Tong; Wang, Shu
2015-10-15
In this paper, we investigate the Klein-Gordon-Schrödinger (KGS) system with higher order Yukawa coupling in spatial dimensions N ≥ 3. We establish a perturbed virial type identity and prove blowup results relied on Lyapunov functionals for KGS system with a negative energy level. Additionally, we give a result with respect to the blowup rate in finite time for the radial solution in 3 spatial dimensions.
Higher-Order Kerr Terms Allow Ionization-Free Filamentation in Gases
NASA Astrophysics Data System (ADS)
Béjot, P.; Kasparian, J.; Henin, S.; Loriot, V.; Vieillard, T.; Hertz, E.; Faucher, O.; Lavorel, B.; Wolf, J.-P.
2010-03-01
We show that higher-order nonlinear indices (n4, n6, n8, n10) provide the main defocusing contribution to self-channeling of ultrashort laser pulses in air and argon at 800 nm, in contrast with the previously accepted mechanism of filamentation where plasma was considered as the dominant defocusing process. Their consideration allows us to reproduce experimentally observed intensities and plasma densities in self-guided filaments.
Higher Order Mode Damper Study of the 56 MHz SRF Cavity
Choi,E.; Hahn, H.
2008-08-01
This report summarizes the study on the higher order mode (HOM) damper for the 56 MHz SRF cavity. The Q factors and frequencies of the HOMs with the HOM damper are measured and compared to the simulation. The high pass filter prototype for rejecting the fundamental mode is designed and tested. The filter measurement is also compared to the simulation. Based on the measurement, a new location of the HOM damper is chosen.
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.
A design study for the addition of higher order parametric discrete elements to NASTRAN
NASA Technical Reports Server (NTRS)
Stanton, E. L.
1972-01-01
The addition of discrete elements to NASTRAN poses significant interface problems with the level 15.1 assembly modules and geometry modules. Potential problems in designing new modules for higher-order parametric discrete elements are reviewed in both areas. An assembly procedure is suggested that separates grid point degrees of freedom on the basis of admissibility. New geometric input data are described that facilitate the definition of surfaces in parametric space.
Higher-Stokes-order Raman conversion of XeCl laser in hydrogen
Komine, H.; Stappaerts, E.A.
1982-04-01
Efficient XeCl-laser Raman downconversion has been demonstrated with a novel oscillator-amplifier system based on higher-Stokes-order generation in H/sub 2/ gas. Simultaneous generation of the first (353-nm), second (414-nm), and third (499-nm) Stokes outputs has been observed in a Raman amplifier at energy-conversion efficiencies of 18, 22, and 14%, respectively, in good agreement with computer simulations.
Sleep inertia, sleep homeostatic and circadian influences on higher-order cognitive functions.
Burke, Tina M; Scheer, Frank A J L; Ronda, Joseph M; Czeisler, Charles A; Wright, Kenneth P
2015-08-01
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-day-long study that included two 14-day-long 28-h 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 during the first ~2-4 h of wakefulness (decreasing sleep inertia); worsened thereafter until scheduled bedtime (increasing sleep homeostasis); and was worst at ~60° and best at ~240° (circadian modulation, with worst and best phases corresponding to ~09:00 and ~21:00 hours, respectively, in individuals with a habitual wake time of 07:00 hours). 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
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.
Constructing Higher-Order DNA Nanoarchitectures with Highly Purified DNA Nanocages.
Xing, Shu; Jiang, Dawei; Li, Fan; Li, Jiang; Li, Qian; Huang, Qing; Guo, Linjie; Xia, Jiaoyun; Shi, Jiye; Fan, Chunhai; Zhang, Lan; Wang, Lihua
2015-06-24
DNA nanostructures have attracted great attention due to their precisely controllable geometry and great potential in various areas including bottom-up self-assembly. However, construction of higher-order DNA nanoarchitectures with individual DNA nanostructures is often hampered with the purity and quantity of these "bricks". Here, we introduced size exclusion chromatography (SEC) to prepare highly purified tetrahedral DNA nanocages in large scale and demonstrated that precise quantification of DNA nanocages was the key to the formation of higher-order DNA nanoarchitectures. We successfully purified a series of DNA nanocages with different sizes, including seven DNA tetrahedra with different edge lengths (7, 10, 13, 17, 20, 26, 30 bp) and one trigonal bipyramid with a 20-bp edge. These highly purified and aggregation-free DNA nanocages could be self-assembled into higher-order DNA nanoarchitectures with extraordinarily high yields (98% for dimer and 95% for trimer). As a comparison, unpurified DNA nanocages resulted in low yield of 14% for dimer and 12% for trimer, respectively. AFM images cleraly presented the characteristic structure of monomer, dimer and trimer, impling the purified DNA nanocages well-formed the designed nanoarchitectures. Therefore, we have demonstrated that highly purified DNA nanocages are excellent "bricks" for DNA nanotechnology and show great potential in various applications of DNA nanomaterials. PMID:25345465
Axicons for mode conversion in high peak power, higher-order mode, fiber amplifiers.
Nicholson, J W; DeSantolo, A; Westbrook, P S; Windeler, R S; Kremp, T; Headley, C; DiGiovanni, D J
2015-12-28
Higher-order mode fiber amplifiers have demonstrated effective areas as large as 6000 μm2, allowing for high pulse energy and peak power amplification. Long-period gratings are used to convert the fundamental mode to the higher-order mode at the entrance to the amplifier, and reconvert back to the fundamental at the exit, to achieve a diffraction limited beam. However, long period gratings are susceptible to nonlinearity at high peak power. In this work, we propose and demonstrate axicons for linear bulk-optic mode conversion at the output of higher order mode amplifiers. We achieve an M2 of less than 1.25 for 80% mode conversion efficiency. Experiments with pulsed amplifiers confirm that the mode conversion is free from nonlinearity. Furthermore, chirp pulse amplifier experiments confirm that HOM amplifiers plus axicon mode convertors provide energy scalability in femtosecond pulses, compared to smaller effective area, fundamental mode fiber amplifiers. We also propose and demonstrate a route towards fiber integration of the axicon mode convertor by fabricating axicons directly on the tip of the fiber amplifier end-cap. PMID:26832045
Purposely Teaching for the Promotion of Higher-order Thinking Skills: A Case of Critical Thinking
NASA Astrophysics Data System (ADS)
Miri, Barak; David, Ben-Chaim; Uri, Zoller
2007-10-01
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 group ( n = 57) consisted of science students who were exposed to teaching strategies designed for enhancing higher order thinking skills. Two other groups: science ( n = 41) and non-science majors ( n = 79), were taught traditionally, and acted as control. By using critical thinking assessment instruments, we have found that the experimental group showed a statistically significant improvement on critical thinking skills components and disposition towards critical thinking subscales, such as truth-seeking, open-mindedness, self-confidence, and maturity, compared with the control groups. Our findings suggest that if teachers purposely and persistently practice higher order thinking strategies for example, dealing in class with real-world problems, encouraging open-ended class discussions, and fostering inquiry-oriented experiments, there is a good chance for a consequent development of critical thinking capabilities.
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.
Howe, George W; Hornberger, Anna P; Weihs, Karen; Moreno, Francisco; Neiderhiser, Jenae M
2012-05-01
Recent work on comorbidity finds evidence for hierarchical structure of mood and anxiety disorders and symptoms. This study tests whether a higher-order internalizing factor accounts for variation in depression and anxiety symptom severity and change over time in a sample experiencing a period of major life stress. Data on symptoms of depression, chronic worry, and social anxiety were collected five times across seven months from 426 individuals who had recently lost jobs. Growth models for each type of symptom found significant variation in individual trajectories. Slopes were highly correlated across symptom type, as were intercepts. Multilevel confirmatory factor analyses found evidence for a higher-order internalizing factor for both slopes and intercepts, reflective of comorbidity of depression and anxiety, with the internalizing factor accounting for 54% to 91% of the variance in slopes and intercepts of specific symptom sets, providing evidence for both a general common factor and domain-specific factors characterizing level and change in symptoms. Loadings on the higher order factors differed modestly for men and women, and when comparing African American and White participants, but did not differ by age, education, or history of depression. More distal factors including gender and history of depression were strongly associated with internalizing in the early weeks after job loss, but rates of change in internalizing were associated most strongly with reemployment. Findings suggest that stressors may contribute in different ways to the common internalizing factor as compared to variance in anxiety and depression that is independent of that factor. PMID:22103803
The usefulness of higher-order constitutive relations for describing the Knudsen layer.
Gallis, Michail A.; Lockerby, Duncan A.; Reese, Jason M.
2005-03-01
The Knudsen layer is an important rarefaction phenomenon in gas flows in and around microdevices. Its accurate and efficient modeling is of critical importance in the design of such systems and in predicting their performance. In this paper we investigate the potential that higher-order continuum equations may have to model the Knudsen layer, and compare their predictions to high-accuracy DSMC (direct simulation Monte Carlo) data, as well as a standard result from kinetic theory. We find that, for a benchmark case, the most common higher-order continuum equation sets (Grad's 13 moment, Burnett, and super-Burnett equations) cannot capture the Knudsen layer. Variants of these equation families have, however, been proposed and some of them can qualitatively describe the Knudsen layer structure. To make quantitative comparisons, we obtain additional boundary conditions (needed for unique solutions to the higher-order equations) from kinetic theory. However, we find the quantitative agreement with kinetic theory and DSMC data is only slight.
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.
High temperature sensing using higher-order-mode rejected sapphire-crystal fiber gratings
NASA Astrophysics Data System (ADS)
Zhan, Chun; Kim, Jae Hun; Lee, Jon; Yin, Stuart; Ruffin, Paul; Luo, Claire
2007-09-01
In this paper, we report the fabrication of higher-order-mode rejected fiber Bragg gratings (FBGs) in sapphire crystal fiber using infrared (IR) femtosecond laser illumination. The grating is tested in high temperature furnace up to 1600 degree Celsius. As sapphire fiber is only available as highly multimode fiber, a scheme to filter out higher order modes in favor for the fundamental mode is theoretically evaluated and experimentally demonstrated. The approach is to use an ultra thin sapphire crystal fiber (60 micron in diameter) to decrease the number of modes. The small diameter fiber also enables bending the fiber to certain radius which is carefully chosen to provide low loss for the fundamental mode LP01 and high loss for the other high-order modes. After bending, less-than-2-nm resonant peak bandwidth is achieved. The grating spectrum is improved, and higher resolution sensing measurement can be achieved. This mode filtering method is very easy to implement. Furthermore, the sapphire fiber is sealed with hi-purity alumina ceramic cement inside a flexible high temperature titanium tube, and the highly flexible titanium tube offers a robust packaging to sapphire fiber. Our high temperature sapphire grating sensor is very promising in extremely high temperature sensing application.
Rajabi, Mohammad Taher; Korouji, Sara; Farjadnia, Mahgol; Naderan, Mohammad; Rajabi, Mohammad Bagher; Khosravi, Bahram; Tabatabaie, Seyed Mehdi
2015-01-01
AIM To compare higher order aberrations in two aspherical intraocular lenses (IOLs): Akreos advanced optics (AO) and Dr. Schmidt Microcrystalline 6125 aspheric anterior surface (MC6125AS) with each other. METHODS Forty eyes of 39 patients underwent phacoemulsification and Akreos AO and MC6125AS were implanted in their eyes in a random manner. Three months post-operatively, higher order aberrations including spherical aberration, coma aberration, and total aberrations were measured and compared. RESULTS The total aberration was 0.24±0.17 in eyes with Dr. Schmidt and 0.20±0.01 in eyes with Akreos AO (P=0.361). The mean of coma aberration was 0.17±0.21 and 0.09±0.86 in Dr. Schmidt and Akreos lenses, respectively (P=0.825). Total spherical aberration was almost the same in both groups (Mean: 0.05, P=0.933). Best corrected visual acuity in Akreos AO (0.10±0.68) and Dr. Schmidt (0.09±0.67) did not differ significantly (P=0.700). CONCLUSION There is no statistically significant difference in the higher order aberrations between these two aspherical lenses. PMID:26086009
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.
Propagation of high power electromagnetic beams in overdense plasmas: Higher order paraxial theory
Sodha, Mahendra Singh; Faisal, Mohammad
2008-03-15
This article presents the paraxial theory of the propagation of an initially Gaussian electromagnetic beam in an inhomogeneous plasma with an overdense region; in contrast to earlier work on penetration in overdense plasma, higher order terms (up to r{sup 4}) in the expansion of the dielectric function and the eikonal have been taken into account. Three types of nonlinearities, viz., collisional, ponderomotive, and relativistic, have been considered. As expected the higher order terms do not affect the critical curves, corresponding to initial propagation without convergence or divergence. It is seen that the inclusion of higher order terms does significantly affect the dependence of the beam width on the distance of propagation. Corresponding to the case of ponderomotive nonlinearity numerical results for the dependence of beam width parameter and the axial dielectric function on the distance of propagation have been presented for specific values of the initial beam width and axial irradiance and specific spatial dependence of the electron density in the absence of the beam. Both the situations, viz., formation of bright or dark rings in the transverse irradiation pattern, have been considered. From a parametric analysis the dependence of the maximum penetration (when the axial dielectric function tends to zero) on the axial irradiance and an inhomogeneity parameter has been graphically illustrated.
Alamia, Andrea; Solopchuk, Oleg; D'Ausilio, Alessandro; Van Bever, Violette; Fadiga, Luciano; Olivier, Etienne; Zénon, Alexandre
2016-03-01
Because Broca's area is known to be involved in many cognitive functions, including language, music, and action processing, several attempts have been made to propose a unifying theory of its role that emphasizes a possible contribution to syntactic processing. Recently, we have postulated that Broca's area might be involved in higher-order chunk processing during implicit learning of a motor sequence. Chunking is an information-processing mechanism that consists of grouping consecutive items in a sequence and is likely to be involved in all of the aforementioned cognitive processes. Demonstrating a contribution of Broca's area to chunking during the learning of a nonmotor sequence that does not involve language could shed new light on its function. To address this issue, we used offline MRI-guided TMS in healthy volunteers to disrupt the activity of either the posterior part of Broca's area (left Brodmann's area [BA] 44) or a control site just before participants learned a perceptual sequence structured in distinct hierarchical levels. We found that disruption of the left BA 44 increased the processing time of stimuli representing the boundaries of higher-order chunks and modified the chunking strategy. The current results highlight the possible role of the left BA 44 in building up effector-independent representations of higher-order events in structured sequences. This might clarify the contribution of Broca's area in processing hierarchical structures, a key mechanism in many cognitive functions, such as language and composite actions. PMID:26765778
Higher order explicit symmetric integrators for inseparable forms of coordinates and momenta
NASA Astrophysics Data System (ADS)
Liu, Lei; Wu, Xin; Huang, Guoqing; Liu, Fuyao
2016-06-01
Pihajoki proposed the extended phase-space second-order explicit symmetric leapfrog methods for inseparable Hamiltonian systems. On the basis of this work, we survey a critical problem on how to mix the variables in the extended phase space. Numerical tests show that sequent permutations of coordinates and momenta can make the leapfrog-like methods yield the most accurate results and the optimal long-term stabilized error behaviour. We also present a novel method to construct many fourth-order extended phase-space explicit symmetric integration schemes. Each scheme represents the symmetric production of six usual second-order leapfrogs without any permutations. This construction consists of four segments: the permuted coordinates, triple product of the usual second-order leapfrog without permutations, the permuted momenta and the triple product of the usual second-order leapfrog without permutations. Similarly, extended phase-space sixth, eighth and other higher order explicit symmetric algorithms are available. We used several inseparable Hamiltonian examples, such as the post-Newtonian approach of non-spinning compact binaries, to show that one of the proposed fourth-order methods is more efficient than the existing methods; examples include the fourth-order explicit symplectic integrators of Chin and the fourth-order explicit and implicit mixed symplectic integrators of Zhong et al. Given a moderate choice for the related mixing and projection maps, the extended phase-space explicit symplectic-like methods are well suited for various inseparable Hamiltonian problems. Samples of these problems involve the algorithmic regularization of gravitational systems with velocity-dependent perturbations in the Solar system and post-Newtonian Hamiltonian formulations of spinning compact objects.
Influence of squeeze film damping on the higher-order modes of clamped–clamped microbeams
NASA Astrophysics Data System (ADS)
Alcheikh, N.; Kosuru, L.; Jaber, N.; Bellaredj, M.; Younis, M. I.
2016-06-01
This paper presents an experimental study and a finite-element analysis of the effect of squeeze film damping on the resonance frequency and quality factor of the higher-order flexure vibrations modes of clamped–clamped microbeams. Viscoelastic and silicon nitride microbeams are fabricated and are electrostatically actuated by various electrode configurations to trigger the first, second, and third modes. The damping characteristic and the resonance frequency of these modes are examined for a wide range of gas pressure and electrostatic voltage loads. The results of the silicon nitride beams and viscoelastic beams are compared. It is found that the intrinsic material loss is the major dissipation mechanism at low pressure for the viscoelastic microbeams, significantly limiting their quality factor. It is also found that while the silicon nitride beams show higher quality factors at the intrinsic and molecular regimes of pressure, due to their low intrinsic loss, their quality factors near atmospheric pressure are lower than those of the viscoelastic microbeams. Further, the higher-order modes of all the beams show much higher quality factors at atmospheric pressure compared to the first mode, which could be promising for operating such resonators in air. Experimental results and finite element model simulations show good agreement for resonance frequency and quality factor for the three studied modes.
A family of higher-order integration methods for structural dynamics
Chang, S.Y.
1996-12-01
A new family of higher-order implicit, one-step integration algorithms has been developed by Chang (1994). These algorithms have minimum order of accuracy two, and maximum order of accuracy four. In general, they have order of accuracy three. All the algorithms are unconditionally stable, do not overshoot in displacements or in velocities and possess desirable numerical dissipation which can be continuously controlled. In particular, these schemes possess better dissipative and dispersive characteristics than the commonly used second-order methods. It has been found that one of these algorithms can provide an appropriate amplitude compensation effect for nonlinear systems. This amplitude compensation effect can effectively suppress the linearization errors which are introduced by the assumption that the structural properties remain constant during each time step. Because of the excellent properties possessed by the algorithm, especially the amplitude compensation effect and no growth of high-frequency response, a time step as large as two orders of magnitude greater than what is needed for the average acceleration method can be used, leading to a very significant saving of computational effort.
Surface-enhanced Raman scattering as a higher-order Raman process
NASA Astrophysics Data System (ADS)
Mueller, Niclas S.; Heeg, Sebastian; Reich, Stephanie
2016-08-01
We propose to understand surface-enhanced Raman scattering (SERS) as a higher-order Raman process that contains the plasmonic excitation. The SERS amplitudes are calculated with third- and fourth-order perturbation theory. Treating the plasmonic excitation as a quasiparticle, we derive analytic expressions for all coupling matrix elements. This leads to a general theory of plasmonic enhancement in SERS that can be applied to arbitrary plasmonic nanostructures. We obtain the plasmon eigenvectors of a gold nanosphere and a nanosphere dimer. They are used to calculate the enhancement of the Raman cross section of a molecule coupled to the dipole plasmon mode. The enhancement of the cross section is up to three orders of magnitude stronger than predicted by the theory of electromagnetic enhancement. The difference is most pronounced in vacuum and decreases with increasing dielectric constant of the embedding medium. The predictions from understanding SERS as a higher-order Raman process agree well with recent experiments; they highlight the dominance of plasmonic enhancement in SERS.
Silva, Carlos A B; Rodrigues, Clóves G; Ramos, J Galvão; Luzzi, Roberto
2015-06-01
Construction, in the framework of a nonequilibrium statistical ensemble formalism, of a higher-order generalized hydrodynamics, also referred to as mesoscopic hydrothermodynamics, that is, covering phenomena involving motion of fluids displaying variations short in space and fast in time-unrestricted values of Knudsen numbers, is presented. In that way, an approach is provided enabling the coupling and simultaneous treatment of the kinetics and hydrodynamic levels of descriptions. It is based on a complete thermostatistical approach in terms of the densities of matter and energy and their fluxes of all orders covering systems arbitrarily driven away from equilibrium. The set of coupled nonlinear integrodifferential hydrodynamic equations is derived. They are the evolution equations of the Gradlike moments of all orders, derived from a generalized kinetic equation built in the framework of the nonequilibrium statistical ensemble formalism. For illustration, the case of a system of particles embedded in a fluid acting as a thermal bath is fully described. The resulting enormous set of coupled evolution equations is of unmanageable proportions, thus requiring in practice to introduce an appropriate description using the smallest possible number of variables. We have obtained a hierarchy of Maxwell times, associated to the set of all the higher-order fluxes, which have a particular relevance in the process of providing criteria for establishing the contraction of description. PMID:26172796
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 {alpha}{sup '} are analyzed through the order {alpha}{sup '8} showing some interesting constraints on higher order gravitational couplings in the effective superstring action such as the absence of R{sup 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 {alpha}{sup '8} like the absence of {zeta}(2){zeta}(3)R{sup 6} terms. Our analysis is valid for any superstring background in any space-time dimension, which allows for a conformal field theory description.
Higher-Order Compact Schemes for Numerical Simulation of Incompressible Flows
NASA Technical Reports Server (NTRS)
Wilson, Robert V.; Demuren, Ayodeji O.; Carpenter, Mark
1998-01-01
A higher order accurate numerical procedure has been developed for solving incompressible Navier-Stokes equations for 2D or 3D fluid flow problems. It is based on low-storage Runge-Kutta schemes for temporal discretization and fourth and sixth order compact finite-difference schemes for spatial discretization. The particular difficulty of satisfying the divergence-free velocity field required in incompressible fluid flow is resolved by solving a Poisson equation for pressure. It is demonstrated that for consistent global accuracy, it is necessary to employ the same order of accuracy in the discretization of the Poisson equation. Special care is also required to achieve the formal temporal accuracy of the Runge-Kutta schemes. The accuracy of the present procedure is demonstrated by application to several pertinent benchmark problems.
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. PMID:21469856
A modified higher order Godunov’s scheme for stiff source conservative hydrodynamics
NASA Astrophysics Data System (ADS)
Miniati, Francesco; Colella, Phillip
2007-06-01
We present an efficient second-order accurate scheme to treat stiff source terms within the framework of higher order Godunov’s methods. We employ Duhamel’s formula to devise a modified predictor step which accounts for the effects of stiff source terms on the conservative fluxes and recovers the correct isothermal behavior in the limit of an infinite cooling/reaction rate. Source term effects on the conservative quantities are fully accounted for by means of a one-step, second-order accurate semi-implicit corrector scheme based on the deferred correction method of Dutt et al. We demonstrate the accurate, stable and convergent results of the proposed method through a set of benchmark problems for a variety of stiffness conditions and source types.
How does participation in inquiry-based activities influence gifted students' higher order thinking?
NASA Astrophysics Data System (ADS)
Reger, Barbara H.
Inquiry-based learning is considered a useful technique to strengthen the critical thinking skills of students. The National Science Standards emphasize its use and the complexities and challenge it provides are well suited for meeting the needs of the gifted. While many studies have documented the effectiveness of this type of instruction, there is a lack of research on growth in higher-order thinking through participation in science inquiry. This study investigated such growth among a small group of gifted fifth-grade students. In this study a group of fifth-grade gifted science students completed a series of three forensics inquiry lessons, and documented questions, ideas and reflections as they constructed evidence to solve a crime. From this class of students, one small group was purposely selected to serve as the focus of the study. Using qualitative techniques, the questions and statements students made as they interacted in the activity were analyzed. Videotaped comments and student logs were coded for emerging patterns and also examined for evidence of increased levels of higher-order thinking based on a rubric that was designed using the six levels of Bloom's Taxonomy. Evidence from this study showed marked increase in and deeper levels of higher-order thinking for two of the students. The other boy and girl showed progress using the inquiry activities, but it was not as evident. The social dynamics of the group seemed to hinder one girl's participation during some of the activities. The social interactions played a role in strengthening the exchange of ideas and thinking skills for the others. The teacher had a tremendous influence over the production of higher-level statements by modeling that level of thinking as she questioned the students. Through her practice of answering a question with a question, she gradually solicited more analytical thinking from her students.
NASA Astrophysics Data System (ADS)
Simon, Nicole A.
Virtual laboratory experiments using interactive computer simulations are not being employed as viable alternatives to laboratory science curriculum at extensive enough rates within higher education. Rote traditional lab experiments are currently the norm and are not addressing inquiry, Critical Thinking, and cognition throughout the laboratory experience, linking with educational technologies (Pyatt & Sims, 2007; 2011; Trundle & Bell, 2010). A causal-comparative quantitative study was conducted with 150 learners enrolled at a two-year community college, to determine the effects of simulation laboratory experiments on Higher-Order Learning, Critical Thinking Skills, and Cognitive Load. The treatment population used simulated experiments, while the non-treatment sections performed traditional expository experiments. A comparison was made using the Revised Two-Factor Study Process survey, Motivated Strategies for Learning Questionnaire, and the Scientific Attitude Inventory survey, using a Repeated Measures ANOVA test for treatment or non-treatment. A main effect of simulated laboratory experiments was found for both Higher-Order Learning, [F (1, 148) = 30.32,p = 0.00, eta2 = 0.12] and Critical Thinking Skills, [F (1, 148) = 14.64,p = 0.00, eta 2 = 0.17] such that simulations showed greater increases than traditional experiments. Post-lab treatment group self-reports indicated increased marginal means (+4.86) in Higher-Order Learning and Critical Thinking Skills, compared to the non-treatment group (+4.71). Simulations also improved the scientific skills and mastery of basic scientific subject matter. It is recommended that additional research recognize that learners' Critical Thinking Skills change due to different instructional methodologies that occur throughout a semester.
Small amplitude solitons in a warm plasma with smaller and higher order relativistic effects
Kalita, B. C.; Das, R.
2007-07-15
Solitons have been investigated in a warm plasma through the Korteweg-de Vries (KdV) equation, considering a smaller relativistic effect for {gamma}{approx_equal}O(v{sup 2}/c{sup 2}) and {gamma}{sub e}{approx_equal}O(u{sup 2}/c{sup 2}) and higher relativistic effects for {gamma}{approx_equal}O(v{sup 4}/c{sup 4}) and {gamma}{sub e}{approx_equal}O(u{sup 4/}c{sup 4}). Compressive fast ion-acoustic solitons are observed to exist in the entire range (u{sub 0}-v{sub 0}) subject to a suitable mathematical condition satisfied by the initial streaming velocities u{sub 0},v{sub 0} of the electrons and the ions, respectively, electron to ion mass ratio Q(=m{sub e}/m{sub i}) and ion to electron temperature ratio {sigma}(=T{sub i}/T{sub e}). Further, rarefactive solitons of pretty small amplitudes are observed in the small upper range of |u{sub 0}-v{sub 0}| for higher order relativistic effect which are found to change parabolically. It is essentially important to report in our model of plasma, that the higher order relativistic effect slows down the soliton speed to V{<=}0.10 for all temperature ratios {sigma} for small amplitude waves. On the other hand, the smaller order relativistic effect permits the soliton to exist even at a relatively much higher speed V<0.30. Solitons of high (negligible) amplitudes are found to generate at the smaller (greater) difference of initial streamings (u{sub 0}-v{sub 0}) corresponding to both the relativistic effects.
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
Surface Ordering of Orbitals at a Higher Temperature in LaCoO3 Thin Film
NASA Astrophysics Data System (ADS)
Yamasaki, Yuichi; Fujioka, Jun; Nakao, Hironori; Okamoto, Jun; Sudayama, Takaaki; Murakami, Youichi; Nakamura, Masao; Kawasaki, Masashi; Arima, Takahisa; Tokura, Yoshinori
2016-02-01
We report on the distinct surface state of electronic orders, including spin, orbital, and spin-state degrees of freedom of Co3+ ion, in an epitaxially strained thin film of LaCoO3 grown on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 (LSAT) substrate. The surface ordered state was detected by the grazing-incidence resonant soft x-ray scattering at Co L-edge, where the probing depth is less than the topmost 4 nm of surface. Comparing with the result of bulk sensitive x-ray diffraction, we revealed that the transition temperature of the orbital order (spin order) at the surface region is about 30 K (20 K) higher (lower) than that of the bulk. A novel phenomenon of the surface order and bulk disorder of the orbital degree of freedom can be attributed to its collective and lattice-coupled nature which is strongly affected by the translational/inversion symmetry breaking at the surface.
Higher-order weakly nonlinear theory for internal waves in three-layer fluid
NASA Astrophysics Data System (ADS)
Kurkina, O. E.; Kurkin, A. A.; Rouvinskaya, E. A.
2012-04-01
Three-layer stratifications are proved to be a proper approximation of sea water density profile in some basins in the World Ocean with specific hydrological conditions. Some shallow basins such as the Baltic Sea and some river estuaries have more or less continuous three-layer vertical structure caused by the interplay of fresh water discharge to the surface and salt water intrusion in the bottom layers. In order to describe the basic features of the internal wave field in such environments it is necessary to introduce a three-layer model. Such models are considerably more complex than the most popular two-layer systems; however, they represent new dynamical effects and allow for much more analytical progress in their studies compared to the fully stratified situation. In the present study two modes of long internal gravity waves in a three-layer fluid are investigated in the framework of higher-order nonlinear evolutionary equations derived with the use of asymptotic procedure from the governing Euler equations for inviscid incompressible layered medium with "rigid lid" and horizontal impermeable bottom. The equations are written upto the fifth order of the perturbation theory for both interfaces for the waves of both modes: first (fast mode) and second (slow mode, so-called double-humped or varicose). For each equation the coefficients of nonlinearity, dispersion and nonlinear dispersion are expressed explicitly in terms of parameters of this fluid configuration. The behavior and signs of the coefficients are analyzed. The necessary order of the equations is discussed and determined for each case. A few nonlinear asymptotic transformations are proposed to reduce higher-order equations to simpler lower-order or well-known integrable equations (Korteweg - de Vries, Gardner equations). Special attention is paid to the situations when the nonlinear terms of lower orders of perturbation theory can vanish. For such situations particular rescaling is performed in order
NASA Astrophysics Data System (ADS)
Hurst, Gregory B.; Wright, John C.
1992-09-01
Multiresonant coherent anti-Stokes Raman spectroscopy is performed with three tunable lasers on perylene doped polymethylmethacrylate (PMMA). Sharp vibronic features can be observed in vibronic scans at constant energy from the parent electronic transition when resonance is established within the inhomogeneously broadened electronic band. These features are attributed to the nonlinear line narrowing predicted by Ouellette and Denariez-Roberge for a higher order saturated coherent anti-Stokes Raman process since line narrowing should be absent for four wave mixing coherent anti-Stokes Raman spectroscopy. It is shown that the features are sharply dependent on the presence of a simultaneous vibrational resonance as is also predicted by the higher order coherent anti-Stokes Raman model. Excited state coherent anti-Stokes Raman spectroscopy with resonance enhancement from higher singlet states does not contribute to the narrow features since such a process would not have vibrational resonances. Conventional two laser coherent anti-Stokes Raman shows only a weak line at the vibronic transition.
NASA Technical Reports Server (NTRS)
Yan, Jue; Shu, Chi-Wang; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
In this paper we review the existing and develop new continuous Galerkin methods for solving time dependent partial differential equations with higher order derivatives in one and multiple space dimensions. We review local discontinuous Galerkin methods for convection diffusion equations involving second derivatives and for KdV type equations involving third derivatives. We then develop new local discontinuous Galerkin methods for the time dependent bi-harmonic type equations involving fourth derivatives, and partial differential equations involving fifth derivatives. For these new methods we present correct interface numerical fluxes and prove L(exp 2) stability for general nonlinear problems. Preliminary numerical examples are shown to illustrate these methods. Finally, we present new results on a post-processing technique, originally designed for methods with good negative-order error estimates, on the local discontinuous Galerkin methods applied to equations with higher derivatives. Numerical experiments show that this technique works as well for the new higher derivative cases, in effectively doubling the rate of convergence with negligible additional computational cost, for linear as well as some nonlinear problems, with a local uniform mesh.
The role of higher education in equitable human development
NASA Astrophysics Data System (ADS)
Peercy, Chavanne; Svenson, Nanette
2016-04-01
As developing countries continue to battle poverty despite strong economic growth, understanding the relationship between equity and human development becomes increasingly important. In this context, equity is not equivalent to equality for any specific outcome such as health status, education or income. It is an objective ideal whereby people's achievements are increasingly dependent upon personal effort, choice and initiative rather than predetermined characteristics such as race, gender and socioeconomic background. As such, equity becomes an issue of moral equality based on the belief that people should be treated as equals, with equal access to life chances. This ideal pursues equal access to public services, infrastructure and rights for all citizens, including the right to education. While evidence suggests that education builds healthier, richer, more equitable societies, research on this has focused predominantly on primary and secondary schooling. The authors of this paper begin with an extensive review of existing research and relevant literature. In the second part of their article, they then report on their own study which furthers the discussion by exploring connections between tertiary education and development using equity as a reflection of human development - a holistic extension of economic development. After extracting relevant data from a number of available world reports by the United Nations, the World Bank and other organisations, they carried out a cross-national statistical analysis designed to examine the relationship between tertiary enrolment levels and a composite equity variable. Their results indicate a strong association between higher post-secondary education levels and higher levels of social equity.
The role of higher education in equitable human development
NASA Astrophysics Data System (ADS)
Peercy, Chavanne; Svenson, Nanette
2016-03-01
As developing countries continue to battle poverty despite strong economic growth, understanding the relationship between equity and human development becomes increasingly important. In this context, equity is not equivalent to equality for any specific outcome such as health status, education or income. It is an objective ideal whereby people's achievements are increasingly dependent upon personal effort, choice and initiative rather than predetermined characteristics such as race, gender and socioeconomic background. As such, equity becomes an issue of moral equality based on the belief that people should be treated as equals, with equal access to life chances. This ideal pursues equal access to public services, infrastructure and rights for all citizens, including the right to education. While evidence suggests that education builds healthier, richer, more equitable societies, research on this has focused predominantly on primary and secondary schooling. The authors of this paper begin with an extensive review of existing research and relevant literature. In the second part of their article, they then report on their own study which furthers the discussion by exploring connections between tertiary education and development using equity as a reflection of human development - a holistic extension of economic development. After extracting relevant data from a number of available world reports by the United Nations, the World Bank and other organisations, they carried out a cross-national statistical analysis designed to examine the relationship between tertiary enrolment levels and a composite equity variable. Their results indicate a strong association between higher post-secondary education levels and higher levels of social equity.
Sutheerawatthana, Pitch; Minato, Takayuki
2010-02-15
The response of a social group is a missing element in the formal impact assessment model. Previous discussion of the involvement of social groups in an intervention has mainly focused on the formation of the intervention. This article discusses the involvement of social groups in a different way. A descriptive model is proposed by incorporating a social group's response into the concept of second- and higher-order effects. The model is developed based on a cause-effect relationship through the observation of phenomena in case studies. The model clarifies the process by which social groups interact with a lower-order effect and then generate a higher-order effect in an iterative manner. This study classifies social groups' responses into three forms-opposing, modifying, and advantage-taking action-and places them in six pathways. The model is expected to be used as an analytical tool for investigating and identifying impacts in the planning stage and as a framework for monitoring social groups' responses during the implementation stage of a policy, plan, program, or project (PPPPs).
Higher order dispersion in the propagation of a gravity wave packet
NASA Technical Reports Server (NTRS)
Yeh, K. C.; Dong, B.
1989-01-01
To the first order of approximation, the complex amplitude of a wave packet in an anisotropic and dispersive medium is convected with the group of velocity. However, a gravity wave is a vector wave. Its wave packet must be formed by superposition of various wave numbers with corresponding frequencies, as is the case for scalar waves, and additionally by superposing many eigenmodes which also depend on the wave number. To represent the vector wave packet self-consistently, it is found that a gradient term must be included in the expansion. For a Guassian wave packet, this gradient term is shown to have important implications on the velocity vector as represented by its hodograph. Numerical results show that the hodograph is influenced by the location of the relative position of interest from the center of a Gaussian pulse. Higher order expansion shows that an initial Gaussian wave packet will retain its Gaussian shape as it propagates, but the pulse will spread in all directions with its major axis undergoing a rotation. Numerical results indicate that these higher order dispersive effects may be marginally observable in the atmosphere.
Higher-order ice-sheet modelling accelerated by multigrid on graphics cards
NASA Astrophysics Data System (ADS)
Brædstrup, Christian; Egholm, David
2013-04-01
Higher-order ice flow modelling is a very computer intensive process owing primarily to the nonlinear influence of the horizontal stress coupling. When applied for simulating long-term glacial landscape evolution, the ice-sheet models must consider very long time series, while both high temporal and spatial resolution is needed to resolve small effects. The use of higher-order and full stokes models have therefore seen very limited usage in this field. However, recent advances in graphics card (GPU) technology for high performance computing have proven extremely efficient in accelerating many large-scale scientific computations. The general purpose GPU (GPGPU) technology is cheap, has a low power consumption and fits into a normal desktop computer. It could therefore provide a powerful tool for many glaciologists working on ice flow models. Our current research focuses on utilising the GPU as a tool in ice-sheet and glacier modelling. To this extent we have implemented the Integrated Second-Order Shallow Ice Approximation (iSOSIA) equations on the device using the finite difference method. To accelerate the computations, the GPU solver uses a non-linear Red-Black Gauss-Seidel iterator coupled with a Full Approximation Scheme (FAS) multigrid setup to further aid convergence. The GPU finite difference implementation provides the inherent parallelization that scales from hundreds to several thousands of cores on newer cards. We demonstrate the efficiency of the GPU multigrid solver using benchmark experiments.
NASA Technical Reports Server (NTRS)
Jothiprasad, Giridhar; Mavriplis, Dimitri J.; Caughey, David A.; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
The efficiency gains obtained using higher-order implicit Runge-Kutta schemes as compared with the second-order accurate backward difference schemes for the unsteady Navier-Stokes equations are investigated. Three different algorithms for solving the nonlinear system of equations arising at each timestep are presented. The first algorithm (NMG) is a pseudo-time-stepping scheme which employs a non-linear full approximation storage (FAS) agglomeration multigrid method to accelerate convergence. The other two algorithms are based on Inexact Newton's methods. The linear system arising at each Newton step is solved using iterative/Krylov techniques and left preconditioning is used to accelerate convergence of the linear solvers. One of the methods (LMG) uses Richardson's iterative scheme for solving the linear system at each Newton step while the other (PGMRES) uses the Generalized Minimal Residual method. Results demonstrating the relative superiority of these Newton's methods based schemes are presented. Efficiency gains as high as 10 are obtained by combining the higher-order time integration schemes with the more efficient nonlinear solvers.
Evidence of Higher-Order Solar Periodicities in China Temperature Record
NASA Astrophysics Data System (ADS)
Tiwari, R. K.; Rajesh, R.; Padmavathi, B.
2016-04-01
We examine here a 2000-year-long record of surface air temperature from China using powerful spectral and statistical analysis techniques to assess the trend and harmonics, if any. Our analyses reveal statistically significant periodicities of order ~900 ± 50, ~480 ± 20, 340 ± 10, ~190 ± 10 and ~130 ± 5 years, which closely match with the known higher-order solar cycles. These periodicities are also similar to quasi-periodicities reported in the climate records of sedimentary cores of subarctic and subpolar regions of North America and North Pacific, thus attesting to the global signature of solar signals in temperature variability. A visual comparison of the temperature series shows that the nodes and antinodes of the underlying temperature variation also match with sunspot variations. We also compare the China temperature (CT) with temperature of northern and southern hemispheres of the past 1000 years. The study reveals strong correlation between the southern hemispheric temperatures and CT during the past 1000 years. However, the northern hemisphere temperature shows strong correlation with CT only during the past century. Interestingly, the variations in the correlation coefficient also have shown periodicities that are nearly identical to the periods observed from CT and higher-order solar cycles. We suggest that the solar irradiance induces global periodic oscillations in temperature records by transporting heat and thermal energy, possibly through the coupling of ocean-atmospheric processes and thereby reinforcing the Sun-ocean-climate link.
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.
Evidence of Higher-Order Solar Periodicities in China Temperature Record
NASA Astrophysics Data System (ADS)
Tiwari, R. K.; Rajesh, R.; Padmavathi, B.
2016-07-01
We examine here a 2000-year-long record of surface air temperature from China using powerful spectral and statistical analysis techniques to assess the trend and harmonics, if any. Our analyses reveal statistically significant periodicities of order ~900 ± 50, ~480 ± 20, 340 ± 10, ~190 ± 10 and ~130 ± 5 years, which closely match with the known higher-order solar cycles. These periodicities are also similar to quasi-periodicities reported in the climate records of sedimentary cores of subarctic and subpolar regions of North America and North Pacific, thus attesting to the global signature of solar signals in temperature variability. A visual comparison of the temperature series shows that the nodes and antinodes of the underlying temperature variation also match with sunspot variations. We also compare the China temperature (CT) with temperature of northern and southern hemispheres of the past 1000 years. The study reveals strong correlation between the southern hemispheric temperatures and CT during the past 1000 years. However, the northern hemisphere temperature shows strong correlation with CT only during the past century. Interestingly, the variations in the correlation coefficient also have shown periodicities that are nearly identical to the periods observed from CT and higher-order solar cycles. We suggest that the solar irradiance induces global periodic oscillations in temperature records by transporting heat and thermal energy, possibly through the coupling of ocean-atmospheric processes and thereby reinforcing the Sun-ocean-climate link.
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.
NASA Technical Reports Server (NTRS)
Stein, Manuel; Sydow, P. Daniel; Librescu, Liviu
1990-01-01
Buckling and postbuckling results are presented for compression-loaded simply-supported aluminum plates and composite plates with a symmetric lay-up of thin + or - 45 deg plies composed of many layers. Buckling results for aluminum plates of finite length are given for various length-to-width ratios. Asymptotes to the curves based on buckling results give N(sub xcr) for plates of infinite length. Postbuckling results for plates with transverse shearing flexibility are compared to results from classical theory for various width-to-thickness ratios. Characteristic curves indicating the average longitudinal direct stress resultant as a function of the applied displacements are calculated based on four different theories: Classical von Karman theory using the Kirchoff assumptions, first-order shear deformation theory, higher-order shear deformation theory, and 3-D flexibility theory. Present results indicate that the 3-D flexibility theory gives the lowest buckling loads. The higher-order shear deformation theory has fewer unknowns than the 3-D flexibility theory but does not take into account through-the-thickness effects. The figures presented show that small differences occur in the average longitudinal direct stress resultants from the four theories that are functions of applied end-shortening displacement.