A phylogenetic analysis of normal modes evolution in enzymes and its relationship to enzyme function

PubMed Central

Lai, Jason; Jin, Jing; Kubelka, Jan; Liberles, David A.

2012-01-01

Since the dynamic nature of protein structures is essential for enzymatic function, it is expected that the functional evolution can be inferred from the changes in the protein dynamics. However, dynamics can also diverge neutrally with sequence substitution between enzymes without changes of function. In this study, a phylogenetic approach is implemented to explore the relationship between enzyme dynamics and function through evolutionary history. Protein dynamics are described by normal mode analysis based on a simplified harmonic potential force field applied to the reduced Cα representation of the protein structure while enzymatic function is described by Enzyme Commission (EC) numbers. Similarity of the binding pocket dynamics at each branch of the protein family’s phylogeny was analyzed in two ways: 1) explicitly by quantifying the normal mode overlap calculated for the reconstructed ancestral proteins at each end and 2) implicitly using a diffusion model to obtain the reconstructed lineage-specific changes in the normal modes. Both explicit and implicit ancestral reconstruction identified generally faster rates of change in dynamics compared with the expected change from neutral evolution at the branches of potential functional divergences for the alpha-amylase, D-isomer specific 2-hydroxyacid dehydrogenase, and copper-containing amine oxidase protein families. Normal modes analysis added additional information over just comparing the RMSD of static structures. However, the branch-specific changes were not statistically significant compared to background function-independent neutral rates of change of dynamic properties and blind application of the analysis would not enable prediction of changes in enzyme specificity. PMID:22651983

A phylogenetic analysis of normal modes evolution in enzymes and its relationship to enzyme function.

PubMed

Lai, Jason; Jin, Jing; Kubelka, Jan; Liberles, David A

2012-09-21

Since the dynamic nature of protein structures is essential for enzymatic function, it is expected that functional evolution can be inferred from the changes in protein dynamics. However, dynamics can also diverge neutrally with sequence substitution between enzymes without changes of function. In this study, a phylogenetic approach is implemented to explore the relationship between enzyme dynamics and function through evolutionary history. Protein dynamics are described by normal mode analysis based on a simplified harmonic potential force field applied to the reduced C(α) representation of the protein structure while enzymatic function is described by Enzyme Commission numbers. Similarity of the binding pocket dynamics at each branch of the protein family's phylogeny was analyzed in two ways: (1) explicitly by quantifying the normal mode overlap calculated for the reconstructed ancestral proteins at each end and (2) implicitly using a diffusion model to obtain the reconstructed lineage-specific changes in the normal modes. Both explicit and implicit ancestral reconstruction identified generally faster rates of change in dynamics compared with the expected change from neutral evolution at the branches of potential functional divergences for the α-amylase, D-isomer-specific 2-hydroxyacid dehydrogenase, and copper-containing amine oxidase protein families. Normal mode analysis added additional information over just comparing the RMSD of static structures. However, the branch-specific changes were not statistically significant compared to background function-independent neutral rates of change of dynamic properties and blind application of the analysis would not enable prediction of changes in enzyme specificity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Normalized modes at selected points without normalization

NASA Astrophysics Data System (ADS)

Kausel, Eduardo

2018-04-01

As every textbook on linear algebra demonstrates, the eigenvectors for the general eigenvalue problem | K - λM | = 0 involving two real, symmetric, positive definite matrices K , M satisfy some well-defined orthogonality conditions. Equally well-known is the fact that those eigenvectors can be normalized so that their modal mass μ =ϕT Mϕ is unity: it suffices to divide each unscaled mode by the square root of the modal mass. Thus, the normalization is the result of an explicit calculation applied to the modes after they were obtained by some means. However, we show herein that the normalized modes are not merely convenient forms of scaling, but that they are actually intrinsic properties of the pair of matrices K , M, that is, the matrices already "know" about normalization even before the modes have been obtained. This means that we can obtain individual components of the normalized modes directly from the eigenvalue problem, and without needing to obtain either all of the modes or for that matter, any one complete mode. These results are achieved by means of the residue theorem of operational calculus, a finding that is rather remarkable inasmuch as the residues themselves do not make use of any orthogonality conditions or normalization in the first place. It appears that this obscure property connecting the general eigenvalue problem of modal analysis with the residue theorem of operational calculus may have been overlooked up until now, but which has in turn interesting theoretical implications.Á

Instantaneous Normal Modes and the Protein Glass Transition

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

Schulz, Roland; Krishnan, Marimuthu; Daidone, Isabella

2009-01-01

In the instantaneous normal mode method, normal mode analysis is performed at instantaneous configurations of a condensed-phase system, leading to modes with negative eigenvalues. These negative modes provide a means of characterizing local anharmonicities of the potential energy surface. Here, we apply instantaneous normal mode to analyze temperature-dependent diffusive dynamics in molecular dynamics simulations of a small protein (a scorpion toxin). Those characteristics of the negative modes are determined that correlate with the dynamical (or glass) transition behavior of the protein, as manifested as an increase in the gradient with T of the average atomic mean-square displacement at ~ 220more » K. The number of negative eigenvalues shows no transition with temperature. Further, although filtering the negative modes to retain only those with eigenvectors corresponding to double-well potentials does reveal a transition in the hydration water, again, no transition in the protein is seen. However, additional filtering of the protein double-well modes, so as to retain only those that, on energy minimization, escape to different regions of configurational space, finally leads to clear protein dynamical transition behavior. Partial minimization of instantaneous configurations is also found to remove nondiffusive imaginary modes. In summary, examination of the form of negative instantaneous normal modes is shown to furnish a physical picture of local diffusive dynamics accompanying the protein glass transition.« less

Instantaneous Normal Modes and the Protein Glass Transition

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

Schultz, Roland; Krishnan, Marimuthu; Daidone, Isabella

2009-01-01

In the instantaneous normal mode method, normal mode analysis is performed at instantaneous configurations of a condensed-phase system, leading to modes with negative eigenvalues. These negative modes provide a means of characterizing local anharmonicities of the potential energy surface. Here, we apply instantaneous normal mode to analyze temperature-dependent diffusive dynamics in molecular dynamics simulations of a small protein (a scorpion toxin). Those characteristics of the negative modes are determined that correlate with the dynamical (or glass) transition behavior of the protein, as manifested as an increase in the gradient with T of the average atomic mean-square displacement at 220 K.more » The number of negative eigenvalues shows no transition with temperature. Further, although filtering the negative modes to retain only those with eigenvectors corresponding to double-well potentials does reveal a transition in the hydration water, again, no transition in the protein is seen. However, additional filtering of the protein double-well modes, so as to retain only those that, on energy minimization, escape to different regions of configurational space, finally leads to clear protein dynamical transition behavior. Partial minimization of instantaneous configurations is also found to remove nondiffusive imaginary modes. In summary, examination of the form of negative instantaneous normal modes is shown to furnish a physical picture of local diffusive dynamics accompanying the protein glass transition.« less

Fast normal mode computations of capsid dynamics inspired by resonance

NASA Astrophysics Data System (ADS)

Na, Hyuntae; Song, Guang

2018-07-01

Increasingly more and larger structural complexes are being determined experimentally. The sizes of these systems pose a formidable computational challenge to the study of their vibrational dynamics by normal mode analysis. To overcome this challenge, this work presents a novel resonance-inspired approach. Tests on large shell structures of protein capsids demonstrate that there is a strong resonance between the vibrations of a whole capsid and those of individual capsomeres. We then show how this resonance can be taken advantage of to significantly speed up normal mode computations.

A quantitative analysis of coupled oscillations using mobile accelerometer sensors

NASA Astrophysics Data System (ADS)

Castro-Palacio, Juan Carlos; Velázquez-Abad, Luisberis; Giménez, Fernando; Monsoriu, Juan A.

2013-05-01

In this paper, smartphone acceleration sensors were used to perform a quantitative analysis of mechanical coupled oscillations. Symmetric and asymmetric normal modes were studied separately in the first two experiments. In the third, a coupled oscillation was studied as a combination of the normal modes. Results indicate that acceleration sensors of smartphones, which are very familiar to students, represent valuable measurement instruments for introductory and first-year physics courses.

Analytical and experimental investigation of a 1/8-scale dynamic model of the shuttle orbiter. Volume 3B: Supporting data

NASA Technical Reports Server (NTRS)

Mason, P. W.; Harris, H. G.; Zalesak, J.; Bernstein, M.

1974-01-01

The NASA Structural Analysis System (NASTRAN) Model 1 finite element idealization, input data, and detailed analytical results are presented. The data presented include: substructuring analysis for normal modes, plots of member data, plots of symmetric free-free modes, plots of antisymmetric free-free modes, analysis of the wing, analysis of the cargo doors, analysis of the payload, and analysis of the orbiter.

Normal modes of the world's oceans: A numerical investigation using Proudman functions

NASA Technical Reports Server (NTRS)

Sanchez, Braulio V.; Morrow, Dennis

1993-01-01

The numerical modeling of the normal modes of the global oceans is addressed. The results of such modeling could be expected to serve as a guide in the analysis of observations and measurements intended to detect these modes. The numerical computation of normal modes of the global oceans is a field in which several investigations have obtained results during the past 15 years. The results seem to be model-dependent to an unsatisfactory extent. Some modeling areas, such as higher resolution of the bathymetry, inclusion of self-attraction and loading, the role of the Arctic Ocean, and systematic testing by means of diagnostic models are addressed. The results show that the present state of the art is such that a final solution to the normal mode problem still lies in the future. The numerical experiments show where some of the difficulties are and give some insight as to how to proceed in the future.

Instantaneous normal mode analysis of the vibrational relaxation of the amide I mode of alanine dipeptide in water.

PubMed

Farag, Marwa H; Zúñiga, José; Requena, Alberto; Bastida, Adolfo

2013-05-28

Nonequilibrium Molecular Dynamics (MD) simulations coupled to instantaneous normal modes (INMs) analysis are used to study the vibrational relaxation of the acetyl and amino-end amide I modes of the alanine dipeptide (AlaD) molecule dissolved in water (D2O). The INMs are assigned in terms of the equilibrium normal modes using the Effective Atomic Min-Cost algorithm as adapted to make use of the outputs of standard MD packages, a method which is well suited for the description of flexible molecules. The relaxation energy curves of both amide I modes show multiexponential decays, in good agreement with the experimental findings. It is found that ~85%-90% of the energy relaxes through intramolecular vibrational redistribution. The main relaxation pathways are also identified. The rate at which energy is transferred into the solvent is similar for the acetyl-end and amino-end amide I modes. The conformational changes occurring during relaxation are investigated, showing that the populations of the alpha and beta region conformers are altered by energy transfer in such a way that it takes 15 ps for the equilibrium conformational populations to be recovered after the initial excitation of the AlaD molecule.

System for determining the angle of impact of an object on a structure

NASA Technical Reports Server (NTRS)

Prosser, William H. (Inventor); Gorman, Michael R. (Inventor)

1993-01-01

A method for determining the angle of impact of an object on a thin-walled structure which determines the angle of impact through analysis of the acoustic waves which result when an object impacts a structure is presented. Transducers are placed on and in the surface of the structure which sense the wave caused in the structure by impact. The waves are recorded and saved for analysis. For source motion normal to the surface, the antisymmetric mode has a large amplitude while that of the symmetric mode is very small. As the source angle increases with respect to the surface normal, the symmetric mode amplitude increases while the antisymmetric mode amplitude decreases. Thus, the angle of impact is determined by measuring the relative amplitudes of these two lowest order modes.

Infrared and Raman Spectroscopy from Ab Initio Molecular Dynamics and Static Normal Mode Analysis: The C–H Region of DMSO as a Case Study

DOE PAGES

Fischer, Sean A.; Ueltschi, Tyler W.; El-Khoury, Patrick Z.; ...

2015-07-29

Carbon-hydrogen (C-H) vibration modes serve as key probes in the chemical identification of hydrocarbons and in vibrational sum-frequency generation (SFG) spectroscopy of hydrocarbons at the liquid/gas interface. Their assignments pose a challenge from a theoretical viewpoint. Here in this work, we present a detailed study of the C-H stretching region of dimethyl sulfoxide (DMSO) using a new Gaussian basis set- based ab initio molecular dynamics (AIMD) module that we have implemented in the NWChem computational chemistry program. By combining AIMD simulations and static normal mode analysis, we interpret experimental infrared and Raman spectra and explore the role of anharmonic effectsmore » in this system. Our anharmonic normal mode analysis of the in-phase and out-of-phase symmetric C-H stretching modes challenges the previous experimental assignment of the shoulder in the symmetric C-H stretching peak as an overtone or Fermi resonance. In addition, our AIMD simulations also show significant broadening of the in-phase symmetric C-H stretching resonance, which suggests that the experimentally observed shoulder is due to thermal broadening of the symmetric stretching resonance.« less

Measurements and Analysis of Reverberation, Target Echo, and Clutter

DTIC Science & Technology

2007-09-30

for Problem 11 (isospeed water). Beyond a few seconds there is excellent agreement between the normal mode (NOGRP and CSNAP), ray (SAFFIRE), and energy...the reverberation, so energy flux or ray -based models are more realistic. More detailed analysis is being developed for a journal paper. 3...comparison of ray , normal-mode, and energy flux results for reverberation in a Pekeris waveguide,” to be presented at special session on Underwater

Normal mode-guided transition pathway generation in proteins

PubMed Central

Lee, Byung Ho; Seo, Sangjae; Kim, Min Hyeok; Kim, Youngjin; Jo, Soojin; Choi, Moon-ki; Lee, Hoomin; Choi, Jae Boong

2017-01-01

The biological function of proteins is closely related to its structural motion. For instance, structurally misfolded proteins do not function properly. Although we are able to experimentally obtain structural information on proteins, it is still challenging to capture their dynamics, such as transition processes. Therefore, we need a simulation method to predict the transition pathways of a protein in order to understand and study large functional deformations. Here, we present a new simulation method called normal mode-guided elastic network interpolation (NGENI) that performs normal modes analysis iteratively to predict transition pathways of proteins. To be more specific, NGENI obtains displacement vectors that determine intermediate structures by interpolating the distance between two end-point conformations, similar to a morphing method called elastic network interpolation. However, the displacement vector is regarded as a linear combination of the normal mode vectors of each intermediate structure, in order to enhance the physical sense of the proposed pathways. As a result, we can generate more reasonable transition pathways geometrically and thermodynamically. By using not only all normal modes, but also in part using only the lowest normal modes, NGENI can still generate reasonable pathways for large deformations in proteins. This study shows that global protein transitions are dominated by collective motion, which means that a few lowest normal modes play an important role in this process. NGENI has considerable merit in terms of computational cost because it is possible to generate transition pathways by partial degrees of freedom, while conventional methods are not capable of this. PMID:29020017

Mode instability in one-dimensional anharmonic lattices: Variational equation approach

NASA Astrophysics Data System (ADS)

Yoshimura, K.

1999-03-01

The stability of normal mode oscillations has been studied in detail under the single-mode excitation condition for the Fermi-Pasta-Ulam-β lattice. Numerical experiments indicate that the mode stability depends strongly on k/N, where k is the wave number of the initially excited mode and N is the number of degrees of freedom in the system. It has been found that this feature does not change when N increases. We propose an average variational equation - approximate version of the variational equation - as a theoretical tool to facilitate a linear stability analysis. It is shown that this strong k/N dependence of the mode stability can be explained from the view point of the linear stability of the relevant orbits. We introduce a low-dimensional approximation of the average variational equation, which approximately describes the time evolution of variations in four normal mode amplitudes. The linear stability analysis based on this four-mode approximation demonstrates that the parametric instability mechanism plays a crucial role in the strong k/N dependence of the mode stability.

Normal mode analysis of the IUS/TDRS payload in a payload canister/transporter environment

NASA Technical Reports Server (NTRS)

Meyer, K. A.

1980-01-01

Special modeling techniques were developed to simulate an accurate mathematical model of the transporter/canister/payload system during ground transport of the Inertial Upper Stage/Tracking and Data Relay Satellite (IUS/TDRS) payload. The three finite element models - the transporter, the canister, and the IUS/TDRS payload - were merged into one model and used along with the NASTRAN normal mode analysis. Deficiencies were found in the NASTRAN program that make a total analysis using modal transient response impractical. It was also discovered that inaccuracies may exist for NASTRAN rigid body modes on large models when Given's method for eigenvalue extraction is employed. The deficiencies as well as recommendations for improving the NASTRAN program are discussed.

Acyl carrier protein structural classification and normal mode analysis

PubMed Central

Cantu, David C; Forrester, Michael J; Charov, Katherine; Reilly, Peter J

2012-01-01

All acyl carrier protein primary and tertiary structures were gathered into the ThYme database. They are classified into 16 families by amino acid sequence similarity, with members of the different families having sequences with statistically highly significant differences. These classifications are supported by tertiary structure superposition analysis. Tertiary structures from a number of families are very similar, suggesting that these families may come from a single distant ancestor. Normal vibrational mode analysis was conducted on experimentally determined freestanding structures, showing greater fluctuations at chain termini and loops than in most helices. Their modes overlap more so within families than between different families. The tertiary structures of three acyl carrier protein families that lacked any known structures were predicted as well. PMID:22374859

Nonlinear normal modes in electrodynamic systems: A nonperturbative approach

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

Kudrin, A. V., E-mail: kud@rf.unn.ru; Kudrina, O. A.; Petrov, E. Yu.

2016-06-15

We consider electromagnetic nonlinear normal modes in cylindrical cavity resonators filled with a nonlinear nondispersive medium. The key feature of the analysis is that exact analytic solutions of the nonlinear field equations are employed to study the mode properties in detail. Based on such a nonperturbative approach, we rigorously prove that the total energy of free nonlinear oscillations in a distributed conservative system, such as that considered in our work, can exactly coincide with the sum of energies of the normal modes of the system. This fact implies that the energy orthogonality property, which has so far been known tomore » hold only for linear oscillations and fields, can also be observed in a nonlinear oscillatory system.« less

Particle-in-cell simulation study on halo formation in anisotropic beams

NASA Astrophysics Data System (ADS)

Ikegami, Masanori

2000-11-01

In a recent paper (M. Ikegami, Nucl. Instr. and Meth. A 435 (1999) 284), we investigated halo formation processes in transversely anisotropic beams based on the particle-core model. The effect of simultaneous excitation of two normal modes of core oscillation, i.e., high- and low-frequency modes, was examined. In the present study, self-consistent particle simulations are performed to confirm the results obtained in the particle-core analysis. In these simulations, it is confirmed that the particle-core analysis can predict the halo extent accurately even in anisotropic situations. Furthermore, we find that the halo intensity is enhanced in some cases where two normal modes of core oscillation are simultaneously excited as expected in the particle-core analysis. This result is of practical importance because pure high-frequency mode oscillation has frequently been assumed in preceding halo studies. The dependence of halo intensity on the 2:1 fixed point locations is also discussed.

"I Treat Him as a Normal Patient": Unveiling the Normalization Coping Strategy Among Formal Caregivers of Persons With Dementia and Its Implications for Person-Centered Care.

PubMed

Bentwich, Miriam Ethel; Dickman, Nomy; Oberman, Amitai; Bokek-Cohen, Ya'arit

2017-11-01

Currently, 47 million people have dementia, worldwide, often requiring paid care by formal caregivers. Research regarding family caregivers suggests normalization as a model for coping with negative emotional outcomes in caring for a person with dementia (PWD). The study aims to explore whether normalization coping mechanism exists among formal caregivers, reveal differences in its application among cross-cultural caregivers, and examine how this coping mechanism may be related to implementing person-centered care for PWDs. Content analysis of interviews with 20 formal caregivers from three cultural groups (Jews born in Israel [JI], Arabs born in Israel [AI], Russian immigrants [RI]), attending to PWDs. We extracted five normalization modes, revealing AI caregivers had substantially more utterances of normalization expressions than their colleagues. The normalization modes most commonly expressed by AI caregivers relate to the personhood of PWDs. These normalization modes may enhance formal caregivers' ability to employ person-centered care.

Analysis of Coherent Phonon Signals by Sparsity-promoting Dynamic Mode Decomposition

NASA Astrophysics Data System (ADS)

Murata, Shin; Aihara, Shingo; Tokuda, Satoru; Iwamitsu, Kazunori; Mizoguchi, Kohji; Akai, Ichiro; Okada, Masato

2018-05-01

We propose a method to decompose normal modes in a coherent phonon (CP) signal by sparsity-promoting dynamic mode decomposition. While the CP signals can be modeled as the sum of finite number of damped oscillators, the conventional method such as Fourier transform adopts continuous bases in a frequency domain. Thus, the uncertainty of frequency appears and it is difficult to estimate the initial phase. Moreover, measurement artifacts are imposed on the CP signal and deforms the Fourier spectrum. In contrast, the proposed method can separate the signal from the artifact precisely and can successfully estimate physical properties of the normal modes.

Normal Mode Analysis on the Relaxation of AN Excited Nitromethane Molecule in Argon Bath

NASA Astrophysics Data System (ADS)

Rivera-Rivera, Luis A.; Wagner, Albert F.

2017-06-01

In our previous work [Rivera-Rivera et al. J. Chem. Phys. 142, 014303 (2015).] classical molecular dynamics simulations followed, in an Ar bath, the relaxation of nitromethane (CH_3NO_2) instantaneously excited by statistically distributing 50 kcal/mol among all its internal degrees of freedom. The 300 K Ar bath was at pressures of 10 to 400 atm. Both rotational and vibrational energies exhibited multi-exponential decay. This study explores mode-specific mechanisms at work in the decay process. With the separation of rotation and vibration developed by Rhee and Kim [J. Chem. Phys. 107, 1394 (1997).], one can show that the vibrational kinetic energy decomposes only into vibrational normal modes while the rotational and Coriolis energies decompose into both vibrational and rotational normal modes. Then the saved CH_3NO_2 positions and momenta can be converted into mode-specific energies whose decay over 1000 ps can be monitored. The results identify vibrational and rotational modes that promote/resist energy lost and drive multi-exponential behavior. In addition to mode-specificity, the results show disruption of IVR with increasing pressure.

Vibrational normal modes of diazo-dimedone: A comparative study by Fourier infrared/Raman spectroscopies and conformational analysis by MM/QM

NASA Astrophysics Data System (ADS)

Téllez Soto, C. A.; Ramos, J. M.; Rianelli, R. S.; de Souza, M. C. B. V.; Ferreira, V. F.

2007-07-01

The 2-diazo-5,5-dimethyl-cyclohexane-1,3-dione ( 3) was synthesized and the FT-IR/Raman spectra were measured with the purpose of obtain a full assignment of the vibrational modes. Singular aspects concerning the -C dbnd N dbnd N oscillator are discussed in view of two strong bands observed in the region of 2300-2100 cm -1 in both, Infrared and Raman spectra. The density functional theory (DFT) was used to obtain the geometrical structure and for assisting in the vibrational assignment joint to the traditional normal coordinate analysis (NCA). The observed wavenumbers at 2145 (IR), 2144(R) are assigned as the coupled ν(N dbnd N) + ν(C dbnd N) vibrational mode with higher participation of the N dbnd N stretching. A 2188 cm -1 (IR) and at 2186 cm -1 (R) can be assigned as a overtone of one of ν(CC) normal mode or to a combination band of the fundamentals δ(CCH) found at 1169 cm -1 and the δ (CC dbnd N) found at 1017 cm -1 enhanced by Fermi resonance.

A NASTRAN primer for the analysis of rotating flexible blades

NASA Technical Reports Server (NTRS)

Lawrence, Charles; Aiello, Robert A.; Ernst, Michael A.; Mcgee, Oliver G.

1987-01-01

This primer provides documentation for using MSC NASTRAN in analyzing rotating flexible blades. The analysis of these blades includes geometrically nonlinear (large displacement) analysis under centrifugal loading, and frequency and mode shape (normal modes) determination. The geometrically nonlinear analysis using NASTRAN Solution sequence 64 is discussed along with the determination of frequencies and mode shapes using Solution Sequence 63. A sample problem with the complete NASTRAN input data is included. Items unique to rotating blade analyses, such as setting angle and centrifugal softening effects are emphasized.

Using Acoustic Structure Quantification During B-Mode Sonography for Evaluation of Hashimoto Thyroiditis.

PubMed

Rhee, Sun Jung; Hong, Hyun Sook; Kim, Chul-Hee; Lee, Eun Hye; Cha, Jang Gyu; Jeong, Sun Hye

2015-12-01

This study aimed to evaluate the usefulness of Acoustic Structure Quantification (ASQ; Toshiba Medical Systems Corporation, Nasushiobara, Japan) values in the diagnosis of Hashimoto thyroiditis using B-mode sonography and to identify a cutoff ASQ level that differentiates Hashimoto thyroiditis from normal thyroid tissue. A total of 186 thyroid lobes with Hashimoto thyroiditis and normal thyroid glands underwent sonography with ASQ imaging. The quantitative results were reported in an echo amplitude analysis (Cm(2)) histogram with average, mode, ratio, standard deviation, blue mode, and blue average values. Receiver operating characteristic curve analysis was performed to assess the diagnostic ability of the ASQ values in differentiating Hashimoto thyroiditis from normal thyroid tissue. Intraclass correlation coefficients of the ASQ values were obtained between 2 observers. Of the 186 thyroid lobes, 103 (55%) had Hashimoto thyroiditis, and 83 (45%) were normal. There was a significant difference between the ASQ values of Hashimoto thyroiditis glands and those of normal glands (P < .001). The ASQ values in patients with Hashimoto thyroiditis were significantly greater than those in patients with normal thyroid glands. The areas under the receiver operating characteristic curves for the ratio, blue average, average, blue mode, mode, and standard deviation were: 0.936, 0.902, 0.893, 0.855, 0.846, and 0.842, respectively. The ratio cutoff value of 0.27 offered the best diagnostic performance, with sensitivity of 87.38% and specificity of 95.18%. The intraclass correlation coefficients ranged from 0.86 to 0.94, which indicated substantial agreement between the observers. Acoustic Structure Quantification is a useful and promising sonographic method for diagnosing Hashimoto thyroiditis. Not only could it be a helpful tool for quantifying thyroid echogenicity, but it also would be useful for diagnosis of Hashimoto thyroiditis. © 2015 by the American Institute of Ultrasound in Medicine.

Harmonic Dynamics of Proteins: Normal Modes and Fluctuations in Bovine Pancreatic Trypsin Inhibitor

NASA Astrophysics Data System (ADS)

Brooks, Bernard; Karplus, Martin

1983-11-01

A normal mode analysis making use of an empirical potential function including local and nonlocal (nonbonded) interactions is performed for the bovine pancreatic trypsin inhibitor in the full conformational space of the molecule (1,740 degrees of freedom); that is, all bond lengths and angles, as well as dihedral angles, are included for the 580-atom system consisting of all heavy atoms and polar hydrogens. The heavy-atom frequency spectrum shows a dense distribution between 3 and 1,800 cm-1, with 350 modes below 216 cm-1. Most of the low-frequency modes, of which many have significant anharmonic character, are found to be delocalized over the protein. The root-mean-square amplitudes of the atomic fluctuations are calculated at 300 K from the normal modes and compared with those obtained from a solution molecular dynamics simulation based on the same potential function; very good agreement is obtained for the variation in the main-chain fluctuations as a function of residue number, though larger differences occur for the side chains. The fluctuations are generally, though not always, dominated by frequencies below 30 cm-1, in accord with the results of the dynamics simulation. The vibrational contributions to the thermodynamic properties of the protein are calculated as a function of temperature; the effects of perturbations on the spectrum, suggested for ligand or substrate binding, are examined. The analysis demonstrates that, in spite of the anharmonic contributions to the potential, a normal mode description can provide useful results concerning the internal motions of proteins.

Normal Mode Analysis of Polytheonamide B

NASA Astrophysics Data System (ADS)

Mori, Takaharu; Kokubo, Hironori; Shimizu, Hirofumi; Iwamoto, Masayuki; Oiki, Shigetoshi; Okamoto, Yuko

2007-09-01

Polytheonamide B is a linear 48-residue peptide which forms a single β-helix structure with alternating d- and l-amino acids and contains methylated and hydroxy variants of proteinogenic amino acids. To investigate the dynamical properties of polytheonamide B we perform the normal mode analysis. Root-mean-square displacements of all backbone atoms, root-mean-square fluctuations of the backbone dihedral angles (φ,\\psi), and correlation factors for the Cα atom fluctuations and for the dihedral angle fluctuations are calculated. The normal mode analysis reveals that polytheonamide B shows the elastic rod behavior in the very low-frequency regions and that librational motions of backbone amide planes have the modes with relatively low frequencies, which is relevant to the function of polytheonamide B. In addition, these librational motions occur almost independently and weakly anticorrelate with those of the hydrogen-bonded neighboring amide planes. Calculations of the backbone fluctuations show that the flexibility of polytheonamide B is roughly uniform over the entire helix. We compare our results with those of gramicidin A, the analogue of polytheonamide B, to discuss the structures and functions, and obtain some common features in the flexibilities and dynamics of the backbone atoms. These results present important clues for clarifying the function of polytheonamide B at the atomic level.

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

Rusu, I; Thomas, T; Roeske, J

Purpose: To identify areas of improvement in our liver stereotactic body radiation therapy (SBRT) program, using failure mode and effect analysis (FMEA). Methods: A multidisciplinary group consisting of one physician, three physicists, one dosimetrist and two therapists was formed. A process map covering 10 major stages of the liver SBRT program from the initial diagnosis to post treatment follow-up was generated. A total of 102 failure modes, together with their causes and effects, were identified. The occurrence (O), severity (S) and lack of detectability (D) were independently scored. The ranking was done using the risk probability number (RPN) defined asmore » the product of average O, S and D numbers for each mode. The scores were normalized to remove inter-observer variability, while preserving individual ranking order. Further, a correlation analysis on the overall agreement on rank order of all failure modes resulted in positive values for successive pairs of evaluators. The failure modes with the highest RPN value were considered for further investigation. Results: The average normalized RPN values for all modes were 39 with a range of 9 to 103. The FMEA analysis resulted in the identification of the top 10 critical failures modes as: Incorrect CT-MR registration, MR scan not performed in treatment position, patient movement between CBCT acquisition and treatment, daily IGRT QA not verified, incorrect or incomplete ITV delineation, OAR contours not verified, inaccurate normal liver effective dose (Veff) calculation, failure of bolus tracking for 4D CT scan, setup instructions not followed for treatment and plan evaluation metrics missed. Conclusion: The application of FMEA to our liver SBRT program led to the identification and possible improvement of areas affecting patient safety.« less

Normal modes of weak colloidal gels

NASA Astrophysics Data System (ADS)

Varga, Zsigmond; Swan, James W.

2018-01-01

The normal modes and relaxation rates of weak colloidal gels are investigated in calculations using different models of the hydrodynamic interactions between suspended particles. The relaxation spectrum is computed for freely draining, Rotne-Prager-Yamakawa, and accelerated Stokesian dynamics approximations of the hydrodynamic mobility in a normal mode analysis of a harmonic network representing several colloidal gels. We find that the density of states and spatial structure of the normal modes are fundamentally altered by long-ranged hydrodynamic coupling among the particles. Short-ranged coupling due to hydrodynamic lubrication affects only the relaxation rates of short-wavelength modes. Hydrodynamic models accounting for long-ranged coupling exhibit a microscopic relaxation rate for each normal mode, λ that scales as l-2, where l is the spatial correlation length of the normal mode. For the freely draining approximation, which neglects long-ranged coupling, the microscopic relaxation rate scales as l-γ, where γ varies between three and two with increasing particle volume fraction. A simple phenomenological model of the internal elastic response to normal mode fluctuations is developed, which shows that long-ranged hydrodynamic interactions play a central role in the viscoelasticity of the gel network. Dynamic simulations of hard spheres that gel in response to short-ranged depletion attractions are used to test the applicability of the density of states predictions. For particle concentrations up to 30% by volume, the power law decay of the relaxation modulus in simulations accounting for long-ranged hydrodynamic interactions agrees with predictions generated by the density of states of the corresponding harmonic networks as well as experimental measurements. For higher volume fractions, excluded volume interactions dominate the stress response, and the prediction from the harmonic network density of states fails. Analogous to the Zimm model in polymer physics, our results indicate that long-ranged hydrodynamic interactions play a crucial role in determining the microscopic dynamics and macroscopic properties of weak colloidal gels.

Spatio-temporal analysis of irregular vocal fold oscillations: Biphonation due to desynchronization of spatial modes

NASA Astrophysics Data System (ADS)

Neubauer, Jürgen; Mergell, Patrick; Eysholdt, Ulrich; Herzel, Hanspeter

2001-12-01

This report is on direct observation and modal analysis of irregular spatio-temporal vibration patterns of vocal fold pathologies in vivo. The observed oscillation patterns are described quantitatively with multiline kymograms, spectral analysis, and spatio-temporal plots. The complex spatio-temporal vibration patterns are decomposed by empirical orthogonal functions into independent vibratory modes. It is shown quantitatively that biphonation can be induced either by left-right asymmetry or by desynchronized anterior-posterior vibratory modes, and the term ``AP (anterior-posterior) biphonation'' is introduced. The presented phonation examples show that for normal phonation the first two modes sufficiently explain the glottal dynamics. The spatio-temporal oscillation pattern associated with biphonation due to left-right asymmetry can be explained by the first three modes. Higher-order modes are required to describe the pattern for biphonation induced by anterior-posterior vibrations. Spatial irregularity is quantified by an entropy measure, which is significantly higher for irregular phonation than for normal phonation. Two asymmetry measures are introduced: the left-right asymmetry and the anterior-posterior asymmetry, as the ratios of the fundamental frequencies of left and right vocal fold and of anterior-posterior modes, respectively. These quantities clearly differentiate between left-right biphonation and anterior-posterior biphonation. This paper proposes methods to analyze quantitatively irregular vocal fold contour patterns in vivo and complements previous findings of desynchronization of vibration modes in computer modes and in in vitro experiments.

Differential Lipid Profiles of Normal Human Brain Matter and Gliomas by Positive and Negative Mode Desorption Electrospray Ionization – Mass Spectrometry Imaging

PubMed Central

Pirro, Valentina; Hattab, Eyas M.; Cohen-Gadol, Aaron A.; Cooks, R. Graham

2016-01-01

Desorption electrospray ionization—mass spectrometry (DESI-MS) imaging was used to analyze unmodified human brain tissue sections from 39 subjects sequentially in the positive and negative ionization modes. Acquisition of both MS polarities allowed more complete analysis of the human brain tumor lipidome as some phospholipids ionize preferentially in the positive and others in the negative ion mode. Normal brain parenchyma, comprised of grey matter and white matter, was differentiated from glioma using positive and negative ion mode DESI-MS lipid profiles with the aid of principal component analysis along with linear discriminant analysis. Principal component–linear discriminant analyses of the positive mode lipid profiles was able to distinguish grey matter, white matter, and glioma with an average sensitivity of 93.2% and specificity of 96.6%, while the negative mode lipid profiles had an average sensitivity of 94.1% and specificity of 97.4%. The positive and negative mode lipid profiles provided complementary information. Principal component–linear discriminant analysis of the combined positive and negative mode lipid profiles, via data fusion, resulted in approximately the same average sensitivity (94.7%) and specificity (97.6%) of the positive and negative modes when used individually. However, they complemented each other by improving the sensitivity and specificity of all classes (grey matter, white matter, and glioma) beyond 90% when used in combination. Further principal component analysis using the fused data resulted in the subgrouping of glioma into two groups associated with grey and white matter, respectively, a separation not apparent in the principal component analysis scores plots of the separate positive and negative mode data. The interrelationship of tumor cell percentage and the lipid profiles is discussed, and how such a measure could be used to measure residual tumor at surgical margins. PMID:27658243

Fatigue of notched fiber composite laminates. Part 1: Analytical model

NASA Technical Reports Server (NTRS)

Mclaughlin, P. V., Jr.; Kulkarni, S. V.; Huang, S. N.; Rosen, B. W.

1975-01-01

A description is given of a semi-empirical, deterministic analysis for prediction and correlation of fatigue crack growth, residual strength, and fatigue lifetime for fiber composite laminates containing notches (holes). The failure model used for the analysis is based upon composite heterogeneous behavior and experimentally observed failure modes under both static and fatigue loading. The analysis is consistent with the wearout philosophy. Axial cracking and transverse cracking failure modes are treated together in the analysis. Cracking off-axis is handled by making a modification to the axial cracking analysis. The analysis predicts notched laminate failure from unidirectional material fatique properties using constant strain laminate analysis techniques. For multidirectional laminates, it is necessary to know lamina fatique behavior under axial normal stress, transverse normal stress and axial shear stress. Examples of the analysis method are given.

Implementation of the block-Krylov boundary flexibility method of component synthesis

NASA Technical Reports Server (NTRS)

Carney, Kelly S.; Abdallah, Ayman A.; Hucklebridge, Arthur A.

1993-01-01

A method of dynamic substructuring is presented which utilizes a set of static Ritz vectors as a replacement for normal eigenvectors in component mode synthesis. This set of Ritz vectors is generated in a recurrence relationship, which has the form of a block-Krylov subspace. The initial seed to the recurrence algorithm is based on the boundary flexibility vectors of the component. This algorithm is not load-dependent, is applicable to both fixed and free-interface boundary components, and results in a general component model appropriate for any type of dynamic analysis. This methodology was implemented in the MSC/NASTRAN normal modes solution sequence using DMAP. The accuracy is found to be comparable to that of component synthesis based upon normal modes. The block-Krylov recurrence algorithm is a series of static solutions and so requires significantly less computation than solving the normal eigenspace problem.

A reduced order, test verified component mode synthesis approach for system modeling applications

NASA Astrophysics Data System (ADS)

Butland, Adam; Avitabile, Peter

2010-05-01

Component mode synthesis (CMS) is a very common approach used for the generation of large system models. In general, these modeling techniques can be separated into two categories: those utilizing a combination of constraint modes and fixed interface normal modes and those based on a combination of free interface normal modes and residual flexibility terms. The major limitation of the methods utilizing constraint modes and fixed interface normal modes is the inability to easily obtain the required information from testing; the result of this limitation is that constraint mode-based techniques are primarily used with numerical models. An alternate approach is proposed which utilizes frequency and shape information acquired from modal testing to update reduced order finite element models using exact analytical model improvement techniques. The connection degrees of freedom are then rigidly constrained in the test verified, reduced order model to provide the boundary conditions necessary for constraint modes and fixed interface normal modes. The CMS approach is then used with this test verified, reduced order model to generate the system model for further analysis. A laboratory structure is used to show the application of the technique with both numerical and simulated experimental components to describe the system and validate the proposed approach. Actual test data is then used in the approach proposed. Due to typical measurement data contaminants that are always included in any test, the measured data is further processed to remove contaminants and is then used in the proposed approach. The final case using improved data with the reduced order, test verified components is shown to produce very acceptable results from the Craig-Bampton component mode synthesis approach. Use of the technique with its strengths and weaknesses are discussed.

Determination of stress intensity factors for interface cracks under mixed-mode loading

NASA Technical Reports Server (NTRS)

Naik, Rajiv A.; Crews, John H., Jr.

1992-01-01

A simple technique was developed using conventional finite element analysis to determine stress intensity factors, K1 and K2, for interface cracks under mixed-mode loading. This technique involves the calculation of crack tip stresses using non-singular finite elements. These stresses are then combined and used in a linear regression procedure to calculate K1 and K2. The technique was demonstrated by calculating three different bimaterial combinations. For the normal loading case, the K's were within 2.6 percent of an exact solution. The normalized K's under shear loading were shown to be related to the normalized K's under normal loading. Based on these relations, a simple equation was derived for calculating K1 and K2 for mixed-mode loading from knowledge of the K's under normal loading. The equation was verified by computing the K's for a mixed-mode case with equal and normal shear loading. The correlation between exact and finite element solutions is within 3.7 percent. This study provides a simple procedure to compute K2/K1 ratio which has been used to characterize the stress state at the crack tip for various combinations of materials and loadings. Tests conducted over a range of K2/K1 ratios could be used to fully characterize interface fracture toughness.

Analysis of the nonlinearity of Asian summer monsoon intraseasonal variability using spherical PDFs

NASA Astrophysics Data System (ADS)

Jajcay, Nikola; Hannachi, Abdel

2013-04-01

The Asian summer monsoon (ASM) is a high-dimensional and highly complex phenomenon affecting more than one fifth of the world population. The intraseasonal component of the ASM undergoes periods of active and break phases associated respectively with enhanced and reduced rainfall over the Indian subcontinent and surroundings. In this paper the nonlinear nature of the intraseasonal monsoon variability is investigated using the leading EOFs of ERA-40 sea level pressure reanalyses field over the ASM region. The probability density function is then computed in spherical coordinates using a Epaneshnikov kernel method. Three significant modes are identified. They represent respectively (i) East - West mode with above normal sea level pressure over East China sea and below normal pressure over Himalayas, (ii) mode with above normal sea level pressure over East China sea (without compensating centre of opposite sign as in (i)) and (iii) mode with below normal sea level pressure over East China sea (same as (ii) but with opposite sign). Relationship to large scale flow are also investigated and discussed.

On the use of attachment modes in substructure coupling for dynamic analysis

NASA Technical Reports Server (NTRS)

Craig, R. R., Jr.; Chang, C.-J.

1977-01-01

Substructure coupling or component-mode synthesis may be employed in the solution of dynamics problems for complex structures. Although numerous substructure-coupling methods have been devised, little attention has been devoted to methods employing attachment modes. In the present paper the various mode sets (normal modes, constraint modes, attachment modes) are defined. A generalized substructure-coupling procedure is described. Those substructure-coupling methods which employ attachment modes are described in detail. One of these methods is shown to lead to results (e.g., system natural frequencies) comparable to or better than those obtained by the Hurty (1965) method.

Evaluation of cell count and classification capabilities in body fluids using a fully automated Sysmex XN equipped with high-sensitive Analysis (hsA) mode and DI-60 hematology analyzer system.

PubMed

Takemura, Hiroyuki; Ai, Tomohiko; Kimura, Konobu; Nagasaka, Kaori; Takahashi, Toshihiro; Tsuchiya, Koji; Yang, Haeun; Konishi, Aya; Uchihashi, Kinya; Horii, Takashi; Tabe, Yoko; Ohsaka, Akimichi

2018-01-01

The XN series automated hematology analyzer has been equipped with a body fluid (BF) mode to count and differentiate leukocytes in BF samples including cerebrospinal fluid (CSF). However, its diagnostic accuracy is not reliable for CSF samples with low cell concentration at the border between normal and pathologic level. To overcome this limitation, a new flow cytometry-based technology, termed "high sensitive analysis (hsA) mode," has been developed. In addition, the XN series analyzer has been equipped with the automated digital cell imaging analyzer DI-60 to classify cell morphology including normal leukocytes differential and abnormal malignant cells detection. Using various BF samples, we evaluated the performance of the XN-hsA mode and DI-60 compared to manual microscopic examination. The reproducibility of the XN-hsA mode showed good results in samples with low cell densities (coefficient of variation; % CV: 7.8% for 6 cells/μL). The linearity of the XN-hsA mode was established up to 938 cells/μL. The cell number obtained using the XN-hsA mode correlated highly with the corresponding microscopic examination. Good correlation was also observed between the DI-60 analyses and manual microscopic classification for all leukocyte types, except monocytes. In conclusion, the combined use of cell counting with the XN-hsA mode and automated morphological analyses using the DI-60 mode is potentially useful for the automated analysis of BF cells.

On Three-dimensional Structures in Relativistic Hydrodynamic Jets

NASA Astrophysics Data System (ADS)

Hardee, Philip E.

2000-04-01

The appearance of wavelike helical structures on steady relativistic jets is studied using a normal mode analysis of the linearized fluid equations. Helical structures produced by the normal modes scale relative to the resonant (most unstable) wavelength and not with the absolute wavelength. The resonant wavelength of the normal modes can be less than the jet radius even on highly relativistic jets. High-pressure regions helically twisted around the jet beam may be confined close to the jet surface, penetrate deeply into the jet interior, or be confined to the jet interior. The high-pressure regions range from thin and ribbon-like to thick and tubelike depending on the mode and wavelength. The wave speeds can be significantly different at different wavelengths but are less than the flow speed. The highest wave speed for the jets studied has a Lorentz factor somewhat more than half that of the underlying flow speed. A maximum pressure fluctuation criterion found through comparison between theory and a set of relativistic axisymmetric jet simulations is applied to estimate the maximum amplitudes of the helical, elliptical, and triangular normal modes. Transverse velocity fluctuations for these asymmetric modes are up to twice the amplitude of those associated with the axisymmetric pinch mode. The maximum amplitude of jet distortions and the accompanying velocity fluctuations at, for example, the resonant wavelength decreases as the Lorentz factor increases. Long-wavelength helical surface mode and shorter wavelength helical first body mode generated structures should be the most significant. Emission from high-pressure regions as they twist around the jet beam can vary significantly as a result of angular variation in the flow direction associated with normal mode structures if they are viewed at about the beaming angle θ=1/γ. Variation in the Doppler boost factor can lead to brightness asymmetries by factors up to 6 as long-wavelength helical structure produced by the helical surface mode winds around the jet. Higher order surface modes and first body modes produce less variation. Angular variation in the flow direction associated with the helical mode appears consistent with precessing jet models that have been proposed to explain the variability in 3C 273 and BL Lac object AO 0235+164. In particular, cyclic angular variation in the flow direction produced by the normal modes could produce the activity seen in BL Lac object OJ 287. Jet precession provides a mechanism for triggering the helical modes on multiple length scales, e.g., the galactic superluminal GRO J1655-40.

Normal coordinate analysis of the vibrational spectrum of benzil molecule

NASA Astrophysics Data System (ADS)

Volovšek, V.; Colombo, L.

1993-03-01

Normal coordinate analysis is performed for the benzil molecule. Force constants of phenyl rings are transferred from earlier studies on binuclear aromatic molecules. The existance of some low-frequency internal modes have been proved, thus eliminating the earlier explanations of the excess of the bands observed in the low-frequency Raman and FIR spectra of benzil crystal.

Linear stability analysis of detonations via numerical computation and dynamic mode decomposition

NASA Astrophysics Data System (ADS)

Kabanov, Dmitry I.; Kasimov, Aslan R.

2018-03-01

We introduce a new method to investigate linear stability of gaseous detonations that is based on an accurate shock-fitting numerical integration of the linearized reactive Euler equations with a subsequent analysis of the computed solution via the dynamic mode decomposition. The method is applied to the detonation models based on both the standard one-step Arrhenius kinetics and two-step exothermic-endothermic reaction kinetics. Stability spectra for all cases are computed and analyzed. The new approach is shown to be a viable alternative to the traditional normal-mode analysis used in detonation theory.

Multivariate frequency domain analysis of protein dynamics

NASA Astrophysics Data System (ADS)

Matsunaga, Yasuhiro; Fuchigami, Sotaro; Kidera, Akinori

2009-03-01

Multivariate frequency domain analysis (MFDA) is proposed to characterize collective vibrational dynamics of protein obtained by a molecular dynamics (MD) simulation. MFDA performs principal component analysis (PCA) for a bandpass filtered multivariate time series using the multitaper method of spectral estimation. By applying MFDA to MD trajectories of bovine pancreatic trypsin inhibitor, we determined the collective vibrational modes in the frequency domain, which were identified by their vibrational frequencies and eigenvectors. At near zero temperature, the vibrational modes determined by MFDA agreed well with those calculated by normal mode analysis. At 300 K, the vibrational modes exhibited characteristic features that were considerably different from the principal modes of the static distribution given by the standard PCA. The influences of aqueous environments were discussed based on two different sets of vibrational modes, one derived from a MD simulation in water and the other from a simulation in vacuum. Using the varimax rotation, an algorithm of the multivariate statistical analysis, the representative orthogonal set of eigenmodes was determined at each vibrational frequency.

Influence of Mixed Mode I-Mode II Loading on Fatigue Delamination Growth Characteristics of a Graphite Epoxy Tape Laminate

NASA Technical Reports Server (NTRS)

Ratcliffe, James G.; Johnston, William M., Jr.

2014-01-01

Mixed mode I-mode II interlaminar tests were conducted on IM7/8552 tape laminates using the mixed-mode bending test. Three mixed mode ratios, G(sub II)/G(sub T) = 0.2, 0.5, and 0.8, were considered. Tests were performed at all three mixed-mode ratios under quasi-static and cyclic loading conditions, where the former static tests were used to determine initial loading levels for the latter fatigue tests. Fatigue tests at each mixed-mode ratio were performed at four loading levels, Gmax, equal to 0.5G(sub c), 0.4G(sub c), 0.3G(sub c), and 0.2G(sub c), where G(sub c) is the interlaminar fracture toughness of the corresponding mixed-mode ratio at which a test was performed. All fatigue tests were performed using constant-amplitude load control and delamination growth was automatically documented using compliance solutions obtained from the corresponding quasi-static tests. Static fracture toughness data yielded a mixed-mode delamination criterion that exhibited monotonic increase in Gc with mixed-mode ratio, G(sub II)/G(sub T). Fatigue delamination onset parameters varied monotonically with G(sub II)/G(sub T), which was expected based on the fracture toughness data. Analysis of non-normalized data yielded a monotonic change in Paris law exponent with mode ratio. This was not the case when normalized data were analyzed. Fatigue data normalized by the static R-curve were most affected in specimens tested at G(sub II)/G(sub T)=0.2 (this process has little influence on the other data). In this case, the normalized data yielded a higher delamination growth rate compared to the raw data for a given loading level. Overall, fiber bridging appeared to be the dominant mechanism, affecting delamination growth rates in specimens tested at different load levels and differing mixed-mode ratios.

Impacts of the horizontal and vertical grids on the numerical solutions of the dynamical equations - Part 1: Nonhydrostatic inertia-gravity modes

NASA Astrophysics Data System (ADS)

Konor, Celal S.; Randall, David A.

2018-05-01

We have used a normal-mode analysis to investigate the impacts of the horizontal and vertical discretizations on the numerical solutions of the nonhydrostatic anelastic inertia-gravity modes on a midlatitude f plane. The dispersion equations are derived from the linearized anelastic equations that are discretized on the Z, C, D, CD, (DC), A, E and B horizontal grids, and on the L and CP vertical grids. The effects of both horizontal grid spacing and vertical wavenumber are analyzed, and the role of nonhydrostatic effects is discussed. We also compare the results of the normal-mode analyses with numerical solutions obtained by running linearized numerical models based on the various horizontal grids. The sources and behaviors of the computational modes in the numerical simulations are also examined.Our normal-mode analyses with the Z, C, D, A, E and B grids generally confirm the conclusions of previous shallow-water studies for the cyclone-resolving scales (with low horizontal wavenumbers). We conclude that, aided by nonhydrostatic effects, the Z and C grids become overall more accurate for cloud-resolving resolutions (with high horizontal wavenumbers) than for the cyclone-resolving scales.A companion paper, Part 2, discusses the impacts of the discretization on the Rossby modes on a midlatitude β plane.

Relativistic stellar stability - Preferred-frame effects

NASA Technical Reports Server (NTRS)

Ni, W.-T.

1974-01-01

In a previous paper, the PPN (parametrized post-Newtonian) formalism was used to analyze relativistic influences on stellar stability in nearly all metric theories of gravity. That analysis omitted all preferred-frame terms. In this paper, possible preferred-frame effects on stellar stability are examined and no new instabilities are found. Although terms linear in the preferred-frame velocity w (time-odd terms, analogous to viscosity and energy generation) change the shapes of the normal modes, their symmetry properties prevent them from changing the characteristic frequencies. Thus, no new vibrational or secular instabilities can occur. Terms quadratic in w do not change either the shapes of the normal modes or the characteristic frequencies for radial pulsations (except for the effects due to the renormalization of the gravitation constant which does not affect stability). Thus, they have no influence on radial stability. Terms quadratic in w do change both the normal modes and the characteristic frequencies of nonradial pulsations; but in the limit of a neutral mode these changes vanish.

Geometric Analysis of Wing Sections

DOT National Transportation Integrated Search

1995-04-01

This paper describes a new geometric analysis procedure for wing sections. This procedure is based on the normal mode analysis for continuous functions. A set of special shape functions is introduced to represent the geometry of the wing section. The...

Impacts of the horizontal and vertical grids on the numerical solutions of the dynamical equations - Part 2: Quasi-geostrophic Rossby modes

NASA Astrophysics Data System (ADS)

Konor, Celal S.; Randall, David A.

2018-05-01

We use a normal-mode analysis to investigate the impacts of the horizontal and vertical discretizations on the numerical solutions of the quasi-geostrophic anelastic baroclinic and barotropic Rossby modes on a midlatitude β plane. The dispersion equations are derived for the linearized anelastic system, discretized on the Z, C, D, CD, (DC), A, E and B horizontal grids, and on the L and CP vertical grids. The effects of various horizontal grid spacings and vertical wavenumbers are discussed. A companion paper, Part 1, discusses the impacts of the discretization on the inertia-gravity modes on a midlatitude f plane.The results of our normal-mode analyses for the Rossby waves overall support the conclusions of the previous studies obtained with the shallow-water equations. We identify an area of disagreement with the E-grid solution.

Vibrational Softening of a Protein on Ligand Binding

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

Balog, Erica; Perahia, David; Smith, Jeremy C

2011-01-01

Neutron scattering experiments have demonstrated that binding of the cancer drug methotrexate softens the low-frequency vibrations of its target protein, dihydrofolate reductase (DHFR). Here, this softening is fully reproduced using atomic detail normal-mode analysis. Decomposition of the vibrational density of states demonstrates that the largest contributions arise from structural elements of DHFR critical to stability and function. Mode-projection analysis reveals an increase of the breathing-like character of the affected vibrational modes consistent with the experimentally observed increased adiabatic compressibility of the protein on complexation.

Relating normal vibrational modes to local vibrational modes with the help of an adiabatic connection scheme

NASA Astrophysics Data System (ADS)

Zou, Wenli; Kalescky, Robert; Kraka, Elfi; Cremer, Dieter

2012-08-01

Information on the electronic structure of a molecule and its chemical bonds is encoded in the molecular normal vibrational modes. However, normal vibrational modes result from a coupling of local vibrational modes, which means that only the latter can provide detailed insight into bonding and other structural features. In this work, it is proven that the adiabatic internal coordinate vibrational modes of Konkoli and Cremer [Int. J. Quantum Chem. 67, 29 (1998)], 10.1002/(SICI)1097-461X(1998)67:1<29::AID-QUA3>3.0.CO;2-0 represent a unique set of local modes that is directly related to the normal vibrational modes. The missing link between these two sets of modes are the compliance constants of Decius, which turn out to be the reciprocals of the local mode force constants of Konkoli and Cremer. Using the compliance constants matrix, the local mode frequencies of any molecule can be converted into its normal mode frequencies with the help of an adiabatic connection scheme that defines the coupling of the local modes in terms of coupling frequencies and reveals how avoided crossings between the local modes lead to changes in the character of the normal modes.

Normal modes of the shallow water system on the cubed sphere

NASA Astrophysics Data System (ADS)

Kang, H. G.; Cheong, H. B.; Lee, C. H.

2017-12-01

Spherical harmonics expressed as the Rossby-Haurwitz waves are the normal modes of non-divergent barotropic model. Among the normal modes in the numerical models, the most unstable mode will contaminate the numerical results, and therefore the investigation of normal mode for a given grid system and a discretiztaion method is important. The cubed-sphere grid which consists of six identical faces has been widely adopted in many atmospheric models. This grid system is non-orthogonal grid so that calculation of the normal mode is quiet challenge problem. In the present study, the normal modes of the shallow water system on the cubed sphere discretized by the spectral element method employing the Gauss-Lobatto Lagrange interpolating polynomials as orthogonal basis functions is investigated. The algebraic equations for the shallow water equation on the cubed sphere are derived, and the huge global matrix is constructed. The linear system representing the eigenvalue-eigenvector relations is solved by numerical libraries. The normal mode calculated for the several horizontal resolution and lamb parameters will be discussed and compared to the normal mode from the spherical harmonics spectral method.

The vibrational spectroscopic studies and molecular property analysis of Estradiol, Tamoxifen and their interaction by density functional theory

NASA Astrophysics Data System (ADS)

Borah, Mukunda Madhab; Gomti Devi, Th.

2018-07-01

In the present work Tamoxifen, Estradiol and their interaction are studied using the experimental and theoretical methodologies. The spectral characterization was made by using Raman, FTIR, DFT and VEDA calculation. The optimization of the molecules have been studied using basis set B3LYP/6-31 G(d,p). Complete vibrational assignment of Tamoxifen, Estradiol and Estradiol + Tamoxifen have been attempted and the potential energy distribution and normal mode analysis had also been carried out to determine the contributions of bond oscillators in each normal mode. We have optimized several binding modes of Estradiol and Tamoxifen and taken the lowest energy conformer in our interest. The molecular geometry, HOMO-LUMO energy gap, molecular hardness (η), ionization energy (IE), electron affinity (EA), total energy and dipole moment were analyzed. The observed experimental and the scaled theoretical results were found in good agreement.

[Raman, FTIR spectra and normal mode analysis of acetanilide].

PubMed

Liang, Hui-Qin; Tao, Ya-Ping; Han, Li-Gang; Han, Yun-Xia; Mo, Yu-Jun

2012-10-01

The Raman and FTIR spectra of acetanilide (ACN) were measured experimentally in the regions of 3 500-50 and 3 500-600 cm(-1) respectively. The equilibrium geometry and vibration frequencies of ACN were calculated based on density functional theory (DFT) method (B3LYP/6-311G(d, p)). The results showed that the theoretical calculation of molecular structure parameters are in good agreement with previous report and better than the ones calculated based on 6-31G(d), and the calculated frequencies agree well with the experimental ones. Potential energy distribution of each frequency was worked out by normal mode analysis, and based on this, a detailed and accurate vibration frequency assignment of ACN was obtained.

Transition from normal to ballistic diffusion in a one-dimensional impact system

NASA Astrophysics Data System (ADS)

Livorati, André L. P.; Kroetz, Tiago; Dettmann, Carl P.; Caldas, Iberê L.; Leonel, Edson D.

2018-03-01

We characterize a transition from normal to ballistic diffusion in a bouncing ball dynamics. The system is composed of a particle, or an ensemble of noninteracting particles, experiencing elastic collisions with a heavy and periodically moving wall under the influence of a constant gravitational field. The dynamics lead to a mixed phase space where chaotic orbits have a free path to move along the velocity axis, presenting a normal diffusion behavior. Depending on the control parameter, one can observe the presence of featured resonances, known as accelerator modes, that lead to a ballistic growth of velocity. Through statistical and numerical analysis of the velocity of the particle, we are able to characterize a transition between the two regimes, where transport properties were used to characterize the scenario of the ballistic regime. Also, in an analysis of the probability of an orbit to reach an accelerator mode as a function of the velocity, we observe a competition between the normal and ballistic transport in the midrange velocity.

Transition from normal to ballistic diffusion in a one-dimensional impact system.

PubMed

Livorati, André L P; Kroetz, Tiago; Dettmann, Carl P; Caldas, Iberê L; Leonel, Edson D

2018-03-01

We characterize a transition from normal to ballistic diffusion in a bouncing ball dynamics. The system is composed of a particle, or an ensemble of noninteracting particles, experiencing elastic collisions with a heavy and periodically moving wall under the influence of a constant gravitational field. The dynamics lead to a mixed phase space where chaotic orbits have a free path to move along the velocity axis, presenting a normal diffusion behavior. Depending on the control parameter, one can observe the presence of featured resonances, known as accelerator modes, that lead to a ballistic growth of velocity. Through statistical and numerical analysis of the velocity of the particle, we are able to characterize a transition between the two regimes, where transport properties were used to characterize the scenario of the ballistic regime. Also, in an analysis of the probability of an orbit to reach an accelerator mode as a function of the velocity, we observe a competition between the normal and ballistic transport in the midrange velocity.

Vibrational spectral investigation on xanthine and its derivatives—theophylline, caffeine and theobromine

NASA Astrophysics Data System (ADS)

Gunasekaran, S.; Sankari, G.; Ponnusamy, S.

2005-01-01

A normal coordinate analysis has been carried out on four compounds having a similar ring structure with different side chain substitutions, which are xanthine, caffeine, theophylline, and theobromine. Xanthine is chemically known as 2,6-dihydroxy purine. Caffeine, theophylline and theobromine are methylated xanthines. Considering the methyl groups as point mass, the number of normal modes of vibrations can be distributed as Γ vib=27 A'+12 A″ based on C s point group symmetry associated with the structures. In the present work 15 A' and 12 A″ normal modes are considered. A new set of orthonormal symmetry co-ordinates have been constructed. Wilson's F- G matrix method has been adopted for the normal coordinate analysis. A satisfactory vibrational band assignment has been made by employing the FTIR and FT Raman spectra of the compounds. The potential energy distribution is calculated with the arrived values of the force constants and hence the agreement of the frequency assignment has been checked.

[Factor structure of regional CBF and CMRglu values as a tool for the study of default mode of the brain].

PubMed

Kataev, G V; Korotkov, A D; Kireev, M V; Medvedev, S V

2013-01-01

In the present article it was shown that the functional connectivity of brain structures, revealed by factor analysis of resting PET CBF and rCMRglu data, is an adequate tool to study the default mode of the human brain. The identification of neuroanatomic systems of default mode (default mode network) during routine clinical PET investigations is important for further studying the functional organization of the normal brain and its reorganizations in pathological conditions.

Lipid Profiles of Canine Invasive Transitional Cell Carcinoma of the Urinary Bladder and Adjacent Normal Tissue by Desorption Electrospray Ionization Imaging Mass Spectrometry

PubMed Central

Dill, Allison L.; Ifa, Demian R.; Manicke, Nicholas E.; Costa, Anthony B.; Ramos-Vara, José A.; Knapp, Deborah W.; Cooks, R. Graham

2009-01-01

Desorption electrospray ionization (DESI) mass spectrometry (MS) was used in an imaging mode to interrogate the lipid profiles of thin tissue sections of canine spontaneous invasive transitional cell carcinoma (TCC) of the urinary bladder (a model of human invasive bladder cancer) as well as adjacent normal tissue from four different dogs. The glycerophospholipids and sphingolipids that appear as intense signals in both the negative ion and positive ion modes were identified by tandem mass spectrometry (MS/MS) product ion scans using collision-induced dissociation. Differences in the relative distributions of the lipid species were present between the tumor and adjacent normal tissue in both the negative and positive ion modes. DESI-MS images showing the spatial distributions of particular glycerophospholipids, sphinoglipids and free fatty acids in both the negative and positive ion modes were compared to serial tissue sections that were stained with hematoxylin and eosin (H&E). Increased absolute and relative intensities for at least five different glycerophospholipids and three free fatty acids in the negative ion mode and at least four different lipid species in the positive ion mode were seen in the tumor region of the samples in all four dogs. In addition, one sphingolipid species exhibited increased signal intensity in the positive ion mode in normal tissue relative to the diseased tissue. Principal component analysis (PCA) was also used to generate unsupervised statistical images from the negative ion mode data and these images are in excellent agreement with the DESI images obtained from the selected ions and also the H&E stained tissue PMID:19810710

Numerical Analysis of Stochastic Dynamical Systems in the Medium-Frequency Range

DTIC Science & Technology

2003-02-01

frequency vibration analysis such as the statistical energy analysis (SEA), the traditional modal analysis (well-suited for high and low: frequency...that the first few structural normal modes primarily constitute the total response. In the higher frequency range, the statistical energy analysis (SEA

Normal mode analysis on the relaxation of an excited nitromethane molecule in argon bath

NASA Astrophysics Data System (ADS)

Rivera-Rivera, Luis; Wagner, Albert

In our previous work [J. Chem. Phys. 142, 014303 (2015)] classical molecular dynamics simulations followed in an Ar bath the relaxation of nitromethane (CH3NO2) instantaneously excited by statistically distributing 50 kcal/mol among all its internal degrees of freedom. The 300 K Ar bath was at pressures of 10 to 400 atm, a range spanning the breakdown of the isolated binary collision approximation. Both rotational and vibrational energies exhibit multi-exponential decay. This study explores mode-specific mechanisms at work in the decay process. With the separation of rotation and vibration developed by Rhee and Kim [J. Chem. Phys. 107, 1394 (1997)], one can show that the vibrational kinetic energy decomposes only into vibrational normal modes while the rotational and Coriolis energies decompose into both vibrational and rotational normal modes. Then the saved CH3NO2 positions and momenta can be converted into mode-specific energies whose decay over 1000 ps can be monitored. The results identify vibrational and rotational modes that promote/resist energy lost and drive multi-exponential behavior. Increasing pressure can be shown to increasingly interfere with post-collision IVR. The work was supported by the U.S. Department of Energy, Office of Science, Chemical Sciences, Geosciences, and Biosciences Division.

Normal mode study of the earth's rigid body motions

NASA Technical Reports Server (NTRS)

Chao, B. F.

1983-01-01

In this paper it is shown that the earth's rigid body (rb) motions can be represented by an analytical set of eigensolutions to the equation of motion for elastic-gravitational free oscillations. Thus each degree of freedom in the rb motion is associated with a rb normal mode. Cases of both nonrotating and rotating earth models are studied, and it is shown that the rb modes do incorporate neatly into the earth's system of normal modes of free oscillation. The excitation formula for the rb modes are also obtained, based on normal mode theory. Physical implications of the results are summarized and the fundamental differences between rb modes and seismic modes are emphasized. In particular, it is ascertained that the Chandler wobble, being one of the rb modes belonging to the rotating earth, can be studied using the established theory of normal modes.

Impacts of the horizontal and vertical grids on the numerical solutions of the dynamical equations – Part 1: Nonhydrostatic inertia–gravity modes

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

Konor, Celal S.; Randall, David A.

We have used a normal-mode analysis to investigate the impacts of the horizontal and vertical discretizations on the numerical solutions of the nonhydrostatic anelastic inertia–gravity modes on a midlatitude f plane. The dispersion equations are derived from the linearized anelastic equations that are discretized on the Z, C, D, CD, (DC), A, E and B horizontal grids, and on the L and CP vertical grids. The effects of both horizontal grid spacing and vertical wavenumber are analyzed, and the role of nonhydrostatic effects is discussed. We also compare the results of the normal-mode analyses with numerical solutions obtained by runningmore » linearized numerical models based on the various horizontal grids. The sources and behaviors of the computational modes in the numerical simulations are also examined.Our normal-mode analyses with the Z, C, D, A, E and B grids generally confirm the conclusions of previous shallow-water studies for the cyclone-resolving scales (with low horizontal wavenumbers). We conclude that, aided by nonhydrostatic effects, the Z and C grids become overall more accurate for cloud-resolving resolutions (with high horizontal wavenumbers) than for the cyclone-resolving scales.A companion paper, Part 2, discusses the impacts of the discretization on the Rossby modes on a midlatitude β plane.« less

Impacts of the horizontal and vertical grids on the numerical solutions of the dynamical equations – Part 1: Nonhydrostatic inertia–gravity modes

DOE PAGES

Konor, Celal S.; Randall, David A.

2018-05-08

We have used a normal-mode analysis to investigate the impacts of the horizontal and vertical discretizations on the numerical solutions of the nonhydrostatic anelastic inertia–gravity modes on a midlatitude f plane. The dispersion equations are derived from the linearized anelastic equations that are discretized on the Z, C, D, CD, (DC), A, E and B horizontal grids, and on the L and CP vertical grids. The effects of both horizontal grid spacing and vertical wavenumber are analyzed, and the role of nonhydrostatic effects is discussed. We also compare the results of the normal-mode analyses with numerical solutions obtained by runningmore » linearized numerical models based on the various horizontal grids. The sources and behaviors of the computational modes in the numerical simulations are also examined.Our normal-mode analyses with the Z, C, D, A, E and B grids generally confirm the conclusions of previous shallow-water studies for the cyclone-resolving scales (with low horizontal wavenumbers). We conclude that, aided by nonhydrostatic effects, the Z and C grids become overall more accurate for cloud-resolving resolutions (with high horizontal wavenumbers) than for the cyclone-resolving scales.A companion paper, Part 2, discusses the impacts of the discretization on the Rossby modes on a midlatitude β plane.« less

Normal modes and mode transformation of pure electron vortex beams

PubMed Central

Thirunavukkarasu, G.; Mousley, M.; Babiker, M.

2017-01-01

Electron vortex beams constitute the first class of matter vortex beams which are currently routinely produced in the laboratory. Here, we briefly review the progress of this nascent field and put forward a natural quantum basis set which we show is suitable for the description of electron vortex beams. The normal modes are truncated Bessel beams (TBBs) defined in the aperture plane or the Fourier transform of the transverse structure of the TBBs (FT-TBBs) in the focal plane of a lens with the said aperture. As these modes are eigenfunctions of the axial orbital angular momentum operator, they can provide a complete description of the two-dimensional transverse distribution of the wave function of any electron vortex beam in such a system, in analogy with the prominent role Laguerre–Gaussian (LG) beams played in the description of optical vortex beams. The characteristics of the normal modes of TBBs and FT-TBBs are described, including the quantized orbital angular momentum (in terms of the winding number l) and the radial index p>0. We present the experimental realization of such beams using computer-generated holograms. The mode analysis can be carried out using astigmatic transformation optics, demonstrating close analogy with the astigmatic mode transformation between LG and Hermite–Gaussian beams. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069769

Normal modes and mode transformation of pure electron vortex beams.

PubMed

Thirunavukkarasu, G; Mousley, M; Babiker, M; Yuan, J

2017-02-28

Electron vortex beams constitute the first class of matter vortex beams which are currently routinely produced in the laboratory. Here, we briefly review the progress of this nascent field and put forward a natural quantum basis set which we show is suitable for the description of electron vortex beams. The normal modes are truncated Bessel beams (TBBs) defined in the aperture plane or the Fourier transform of the transverse structure of the TBBs (FT-TBBs) in the focal plane of a lens with the said aperture. As these modes are eigenfunctions of the axial orbital angular momentum operator, they can provide a complete description of the two-dimensional transverse distribution of the wave function of any electron vortex beam in such a system, in analogy with the prominent role Laguerre-Gaussian (LG) beams played in the description of optical vortex beams. The characteristics of the normal modes of TBBs and FT-TBBs are described, including the quantized orbital angular momentum (in terms of the winding number l) and the radial index p>0. We present the experimental realization of such beams using computer-generated holograms. The mode analysis can be carried out using astigmatic transformation optics, demonstrating close analogy with the astigmatic mode transformation between LG and Hermite-Gaussian beams.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

Polarization Behavior Across Profile Modes For B0329+54: What Consistent Non-RVM Polarization Tells About the Emission Processes

NASA Astrophysics Data System (ADS)

Brinkman-Traverse, Casey; Rankin, Joanna M.; Mitra, Dipanjan

2017-01-01

In this paper, we analyze the quirky polarization behavior across different profile modes for the pulsar B0329+54. We have multi-frequency observations in both the normal and abnormal profile modes, and have identified a non-RVM polarization kink in the core component of the emission. Mitra et al initially identified this kink in the normal profile mode of the pulsar in 2007, and a mirror analysis has been done here for abnormal profile modes at three different frequencies. This kink is intensity dependent, showing up only in the abberated/retarded high intensity pulses, and is frequency independent. This parallel between profile modes shows that the same geometric phenomenon—a height dependent amplifier—is responsible for the non-RVM polarization behavior in each. The question then arises: what can be the source of the profile change, which does not change the polarization characteristics of the pulsar. This pulsar gives us a unique opportunity to study the process of pulsar emission by showing what cannot be responsible for switches in profile mode, and thus profile shape.

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

Fischer, Sean A.; Ueltschi, Tyler W.; El-Khoury, Patrick Z.

Carbon-hydrogen (C-H) vibration modes serve as key probes in the chemical identification of hydrocarbons and in vibrational sum-frequency generation (SFG) spectroscopy of hydrocarbons at the liquid/gas interface. Their assignments pose a challenge from a theoretical viewpoint. Here in this work, we present a detailed study of the C-H stretching region of dimethyl sulfoxide (DMSO) using a new Gaussian basis set- based ab initio molecular dynamics (AIMD) module that we have implemented in the NWChem computational chemistry program. By combining AIMD simulations and static normal mode analysis, we interpret experimental infrared and Raman spectra and explore the role of anharmonic effectsmore » in this system. Our anharmonic normal mode analysis of the in-phase and out-of-phase symmetric C-H stretching modes challenges the previous experimental assignment of the shoulder in the symmetric C-H stretching peak as an overtone or Fermi resonance. In addition, our AIMD simulations also show significant broadening of the in-phase symmetric C-H stretching resonance, which suggests that the experimentally observed shoulder is due to thermal broadening of the symmetric stretching resonance.« less

Analysis of complex elastic structures by a Rayleigh-Ritz component modes method using Lagrange multipliers. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Klein, L. R.

1974-01-01

The free vibrations of elastic structures of arbitrary complexity were analyzed in terms of their component modes. The method was based upon the use of the normal unconstrained modes of the components in a Rayleigh-Ritz analysis. The continuity conditions were enforced by means of Lagrange Multipliers. Examples of the structures considered are: (1) beams with nonuniform properties; (2) airplane structures with high or low aspect ratio lifting surface components; (3) the oblique wing airplane; and (4) plate structures. The method was also applied to the analysis of modal damping of linear elastic structures. Convergence of the method versus the number of modes per component and/or the number of components is discussed and compared to more conventional approaches, ad-hoc methods, and experimental results.

Rheology of Foam Near the Order-Disorder Transition

NASA Technical Reports Server (NTRS)

Holt, R. Glynn; McDaniel, J. Gregory

2001-01-01

The first part of our research results are summarized in the recent journal publication: J. Gregory McDaniel and R. Glynn Holt, 'Measurement of aqueous foam rheology by acoustic levitation', Phys. Rev. E 61, 2204 (2000). This aspect of the work was a combination of experiment and analysis. We built a levitation system capable of acoustically levitating small samples of aqueous foam of arbitrary gas and liquid volume fractions. We then modulated the acoustic field to induce normal mode oscillations of the foam samples. The observables from the experiment were frequency and mode number. For dry (roughly > 70% gas by volume) foams and small deformations, we developed an effective medium, normal-modes analysis which took the frequency and mode number from experiment, and gave us the shear elastic modulus of the foam as a function of Poisson's ratio. The second part of our results may be found in a soon-to-be submitted manuscript 'Dynamics of aqueous foam drops', I.Sh. Akhatov, J.G. McDaniel and R.G. Holt, describing our modeling in the wet foam limit by considering the acoustic problem. This aspect of the research is purely theoretical. Beginning from a mass-conserving mixture law, the fully nonlinear equations of motion for a wet (roughly < 10% gas by volume) foam drop of initially spherical shape were derived. The frequencies for normal mode oscillations were derived in the linear inviscid limit. The nonlinear equations were numerically solved to elicit the motion of a foam drop under acoustic excitation. The role of the time-varying void fraction in breathing-mode oscillations is of particular interest. As of the end of the current (NAG#3-2121) grant, this work was not yet concluded. We continue to work on this aspect in order to extend the analysis to cover the transition regime of gas volume fractions, as well as to compare to experiments in the wet regime.

Application of THz Vibrational Spectroscopy to Molecular Characterization and the Theoretical Fundamentals: An Illustration Using Saccharide Molecules.

PubMed

Zhang, Feng; Wang, Houng-Wei; Tominaga, Keisuke; Hayashi, Michitoshi; Hasunuma, Tomohisa; Kondo, Akihiko

2017-02-01

This work illustrates several theoretical fundamentals for the application of THz vibrational spectroscopy to molecular characterization in the solid state using two different types of saccharide systems as examples. Four subjects have been specifically addressed: (1) the qualitative differences in the molecular vibrational signatures monitored by THz and mid-IR vibrational spectroscopy; (2) the selection rules for THz vibrational spectroscopy as applied to crystalline and amorphous systems; (3) a normal mode simulation, using α-l-xylose as an example; and (4) a rigorous mode analysis to quantify the percentage contributions of the intermolecular and intramolecular vibrations to the normal mode of interest. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Density-cluster NMA: A new protein decomposition technique for coarse-grained normal mode analysis.

PubMed

Demerdash, Omar N A; Mitchell, Julie C

2012-07-01

Normal mode analysis has emerged as a useful technique for investigating protein motions on long time scales. This is largely due to the advent of coarse-graining techniques, particularly Hooke's Law-based potentials and the rotational-translational blocking (RTB) method for reducing the size of the force-constant matrix, the Hessian. Here we present a new method for domain decomposition for use in RTB that is based on hierarchical clustering of atomic density gradients, which we call Density-Cluster RTB (DCRTB). The method reduces the number of degrees of freedom by 85-90% compared with the standard blocking approaches. We compared the normal modes from DCRTB against standard RTB using 1-4 residues in sequence in a single block, with good agreement between the two methods. We also show that Density-Cluster RTB and standard RTB perform well in capturing the experimentally determined direction of conformational change. Significantly, we report superior correlation of DCRTB with B-factors compared with 1-4 residue per block RTB. Finally, we show significant reduction in computational cost for Density-Cluster RTB that is nearly 100-fold for many examples. Copyright © 2012 Wiley Periodicals, Inc.

Pathological speech signal analysis and classification using empirical mode decomposition.

PubMed

Kaleem, Muhammad; Ghoraani, Behnaz; Guergachi, Aziz; Krishnan, Sridhar

2013-07-01

Automated classification of normal and pathological speech signals can provide an objective and accurate mechanism for pathological speech diagnosis, and is an active area of research. A large part of this research is based on analysis of acoustic measures extracted from sustained vowels. However, sustained vowels do not reflect real-world attributes of voice as effectively as continuous speech, which can take into account important attributes of speech such as rapid voice onset and termination, changes in voice frequency and amplitude, and sudden discontinuities in speech. This paper presents a methodology based on empirical mode decomposition (EMD) for classification of continuous normal and pathological speech signals obtained from a well-known database. EMD is used to decompose randomly chosen portions of speech signals into intrinsic mode functions, which are then analyzed to extract meaningful temporal and spectral features, including true instantaneous features which can capture discriminative information in signals hidden at local time-scales. A total of six features are extracted, and a linear classifier is used with the feature vector to classify continuous speech portions obtained from a database consisting of 51 normal and 161 pathological speakers. A classification accuracy of 95.7 % is obtained, thus demonstrating the effectiveness of the methodology.

AlloPred: prediction of allosteric pockets on proteins using normal mode perturbation analysis.

PubMed

Greener, Joe G; Sternberg, Michael J E

2015-10-23

Despite being hugely important in biological processes, allostery is poorly understood and no universal mechanism has been discovered. Allosteric drugs are a largely unexplored prospect with many potential advantages over orthosteric drugs. Computational methods to predict allosteric sites on proteins are needed to aid the discovery of allosteric drugs, as well as to advance our fundamental understanding of allostery. AlloPred, a novel method to predict allosteric pockets on proteins, was developed. AlloPred uses perturbation of normal modes alongside pocket descriptors in a machine learning approach that ranks the pockets on a protein. AlloPred ranked an allosteric pocket top for 23 out of 40 known allosteric proteins, showing comparable and complementary performance to two existing methods. In 28 of 40 cases an allosteric pocket was ranked first or second. The AlloPred web server, freely available at http://www.sbg.bio.ic.ac.uk/allopred/home, allows visualisation and analysis of predictions. The source code and dataset information are also available from this site. Perturbation of normal modes can enhance our ability to predict allosteric sites on proteins. Computational methods such as AlloPred assist drug discovery efforts by suggesting sites on proteins for further experimental study.

Comparative study of cluster Ag17Cu2 by instantaneous normal mode analysis and by isothermal Brownian-type molecular dynamics simulation.

PubMed

Tang, Ping-Han; Wu, Ten-Ming; Yen, Tsung-Wen; Lai, S K; Hsu, P J

2011-09-07

We perform isothermal Brownian-type molecular dynamics simulations to obtain the velocity autocorrelation function and its time Fourier-transformed power spectral density for the metallic cluster Ag(17)Cu(2). The temperature dependences of these dynamical quantities from T = 0 to 1500 K were examined and across this temperature range the cluster melting temperature T(m), which we define to be the principal maximum position of the specific heat is determined. The instantaneous normal mode analysis is then used to dissect the cluster dynamics by calculating the vibrational instantaneous normal mode density of states and hence its frequency integrated value I(j) which is an ensemble average of all vibrational projection operators for the jth atom in the cluster. In addition to comparing the results with simulation data, we look more closely at the entities I(j) of all atoms using the point group symmetry and diagnose their temperature variations. We find that I(j) exhibit features that may be used to deduce T(m), which turns out to agree very well with those inferred from the power spectral density and specific heat. © 2011 American Institute of Physics

Linear perturbations of black holes: stability, quasi-normal modes and tails

NASA Astrophysics Data System (ADS)

Zhidenko, Alexander

2009-03-01

Black holes have their proper oscillations, which are called the quasi-normal modes. The proper oscillations of astrophysical black holes can be observed in the nearest future with the help of gravitational wave detectors. Quasi-normal modes are also very important in the context of testing of the stability of black objects, the anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence and in higher dimensional theories, such as the brane-world scenarios and string theory. This dissertation reviews a number of works, which provide a thorough study of the quasi-normal spectrum of a wide class of black holes in four and higher dimensions for fields of various spin and gravitational perturbations. We have studied numerically the dependance of the quasi-normal modes on a number of factors, such as the presence of the cosmological constant, the Gauss-Bonnet parameter or the aether in the space-time, the dependance of the spectrum on parameters of the black hole and fields under consideration. By the analysis of the quasi-normal spectrum, we have studied the stability of higher dimensional Reissner-Nordstrom-de Sitter black holes, Kaluza-Klein black holes with squashed horizons, Gauss-Bonnet black holes and black strings. Special attention is paid to the evolution of massive fields in the background of various black holes. We have considered their quasi-normal ringing and the late-time tails. In addition, we present two new numerical techniques: a generalisation of the Nollert improvement of the Frobenius method for higher dimensional problems and a qualitatively new method, which allows to calculate quasi-normal frequencies for black holes, which metrics are not known analytically.

iMODS: internal coordinates normal mode analysis server.

PubMed

López-Blanco, José Ramón; Aliaga, José I; Quintana-Ortí, Enrique S; Chacón, Pablo

2014-07-01

Normal mode analysis (NMA) in internal (dihedral) coordinates naturally reproduces the collective functional motions of biological macromolecules. iMODS facilitates the exploration of such modes and generates feasible transition pathways between two homologous structures, even with large macromolecules. The distinctive internal coordinate formulation improves the efficiency of NMA and extends its applicability while implicitly maintaining stereochemistry. Vibrational analysis, motion animations and morphing trajectories can be easily carried out at different resolution scales almost interactively. The server is versatile; non-specialists can rapidly characterize potential conformational changes, whereas advanced users can customize the model resolution with multiple coarse-grained atomic representations and elastic network potentials. iMODS supports advanced visualization capabilities for illustrating collective motions, including an improved affine-model-based arrow representation of domain dynamics. The generated all-heavy-atoms conformations can be used to introduce flexibility for more advanced modeling or sampling strategies. The server is free and open to all users with no login requirement at http://imods.chaconlab.org. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Local vibrational modes of the water dimer - Comparison of theory and experiment

NASA Astrophysics Data System (ADS)

Kalescky, R.; Zou, W.; Kraka, E.; Cremer, D.

2012-12-01

Local and normal vibrational modes of the water dimer are calculated at the CCSD(T)/CBS level of theory. The local H-bond stretching frequency is 528 cm-1 compared to a normal mode stretching frequency of just 143 cm-1. The adiabatic connection scheme between local and normal vibrational modes reveals that the lowering is due to mass coupling, a change in the anharmonicity, and coupling with the local HOH bending modes. The local mode stretching force constant is related to the strength of the H-bond whereas the normal mode stretching force constant and frequency lead to an erroneous underestimation of the H-bond strength.

Integrating protein structural dynamics and evolutionary analysis with Bio3D.

PubMed

Skjærven, Lars; Yao, Xin-Qiu; Scarabelli, Guido; Grant, Barry J

2014-12-10

Popular bioinformatics approaches for studying protein functional dynamics include comparisons of crystallographic structures, molecular dynamics simulations and normal mode analysis. However, determining how observed displacements and predicted motions from these traditionally separate analyses relate to each other, as well as to the evolution of sequence, structure and function within large protein families, remains a considerable challenge. This is in part due to the general lack of tools that integrate information of molecular structure, dynamics and evolution. Here, we describe the integration of new methodologies for evolutionary sequence, structure and simulation analysis into the Bio3D package. This major update includes unique high-throughput normal mode analysis for examining and contrasting the dynamics of related proteins with non-identical sequences and structures, as well as new methods for quantifying dynamical couplings and their residue-wise dissection from correlation network analysis. These new methodologies are integrated with major biomolecular databases as well as established methods for evolutionary sequence and comparative structural analysis. New functionality for directly comparing results derived from normal modes, molecular dynamics and principal component analysis of heterogeneous experimental structure distributions is also included. We demonstrate these integrated capabilities with example applications to dihydrofolate reductase and heterotrimeric G-protein families along with a discussion of the mechanistic insight provided in each case. The integration of structural dynamics and evolutionary analysis in Bio3D enables researchers to go beyond a prediction of single protein dynamics to investigate dynamical features across large protein families. The Bio3D package is distributed with full source code and extensive documentation as a platform independent R package under a GPL2 license from http://thegrantlab.org/bio3d/ .

Impacts of the horizontal and vertical grids on the numerical solutions of the dynamical equations – Part 2: Quasi-geostrophic Rossby modes

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

Konor, Celal S.; Randall, David A.

We use a normal-mode analysis to investigate the impacts of the horizontal and vertical discretizations on the numerical solutions of the quasi-geostrophic anelastic baroclinic and barotropic Rossby modes on a midlatitude β plane. The dispersion equations are derived for the linearized anelastic system, discretized on the Z, C, D, CD, (DC), A, E and B horizontal grids, and on the L and CP vertical grids. The effects of various horizontal grid spacings and vertical wavenumbers are discussed. A companion paper, Part 1, discusses the impacts of the discretization on the inertia–gravity modes on a midlatitude f plane.The results of our normal-modemore » analyses for the Rossby waves overall support the conclusions of the previous studies obtained with the shallow-water equations. We identify an area of disagreement with the E-grid solution.« less

Impacts of the horizontal and vertical grids on the numerical solutions of the dynamical equations – Part 2: Quasi-geostrophic Rossby modes

DOE PAGES

Konor, Celal S.; Randall, David A.

2018-05-08

We use a normal-mode analysis to investigate the impacts of the horizontal and vertical discretizations on the numerical solutions of the quasi-geostrophic anelastic baroclinic and barotropic Rossby modes on a midlatitude β plane. The dispersion equations are derived for the linearized anelastic system, discretized on the Z, C, D, CD, (DC), A, E and B horizontal grids, and on the L and CP vertical grids. The effects of various horizontal grid spacings and vertical wavenumbers are discussed. A companion paper, Part 1, discusses the impacts of the discretization on the inertia–gravity modes on a midlatitude f plane.The results of our normal-modemore » analyses for the Rossby waves overall support the conclusions of the previous studies obtained with the shallow-water equations. We identify an area of disagreement with the E-grid solution.« less

ON SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY. FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

Control logic for exhaust gas driven turbocharger

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

Adeff, G.A.

1991-12-31

This patent describes a method of controlling an exhaust gas driven turbocharger supplying charge air for an internal combustion engine powering vehicle, the turbocharger being adjustable from a normal mode to a power mode in which the charge air available to the engine during vehicle acceleration is increased over that available when the turbocharger is in the normal mode, the vehicle including engine power control means switchable by the vehicle operator from a normal mode to a power mode so that the vehicle operator may selectively elect either the normal mode or the power mode, comprising the steps of measuringmore » the speed of the vehicle, permitting the vehicle operator to elect either the power mode or the normal mode for a subsequent vehicle acceleration, and then adjusting the turbocharger to the power mode when the speed of the vehicle is less than a predetermined reference speed and the vehicle operator has elected to power mode to increase the charge air available to the engine and thereby increasing engine power on a subsequent acceleration of the vehicle.« less

Scaling and interaction of self-similar modes in models of high Reynolds number wall turbulence.

PubMed

Sharma, A S; Moarref, R; McKeon, B J

2017-03-13

Previous work has established the usefulness of the resolvent operator that maps the terms nonlinear in the turbulent fluctuations to the fluctuations themselves. Further work has described the self-similarity of the resolvent arising from that of the mean velocity profile. The orthogonal modes provided by the resolvent analysis describe the wall-normal coherence of the motions and inherit that self-similarity. In this contribution, we present the implications of this similarity for the nonlinear interaction between modes with different scales and wall-normal locations. By considering the nonlinear interactions between modes, it is shown that much of the turbulence scaling behaviour in the logarithmic region can be determined from a single arbitrarily chosen reference plane. Thus, the geometric scaling of the modes is impressed upon the nonlinear interaction between modes. Implications of these observations on the self-sustaining mechanisms of wall turbulence, modelling and simulation are outlined.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

Normal-mode-based analysis of electron plasma waves with second-order Hermitian formalism

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

Ramos, J. J.; White, R. L.

The classic problem of the dynamic evolution and Landau damping of linear Langmuir electron waves in a collisionless plasma with Maxwellian background is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-invariant solution for any initial-value problem. Examples are then given for specific initial conditions that illustrate different behaviors of the Landau-damped macroscopic moments of the perturbations.

Normal-mode-based analysis of electron plasma waves with second-order Hermitian formalism

DOE PAGES

Ramos, J. J.; White, R. L.

2018-03-01

The classic problem of the dynamic evolution and Landau damping of linear Langmuir electron waves in a collisionless plasma with Maxwellian background is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-invariant solution for any initial-value problem. Examples are then given for specific initial conditions that illustrate different behaviors of the Landau-damped macroscopic moments of the perturbations.

Finite element analysis of a percussion device for pulmonary diagnostics

NASA Astrophysics Data System (ADS)

Dhar, Aneesh

A pneumothorax is a medical condition where one or both lungs are unable to remain expanded due to air in the pleural space. Finite Element Analysis simulations were conducted on a Percussion Device, which is able to diagnose a pneumothorax using an automated percussion technique. The simulations helped determine the natural modes of vibration of the Percussion Device. These modes were then compared to the motion experimentally measured by an accelerometer on the Percussion Device. It was observed that the modes of the percussion head occurred in the range of 0 to 100 Hz, while the sensor membrane modes occurred in the range of 600 to 900 Hz. Most of these modes were found to match with peaks in the experimental spectra. The simulations performed are reliable and provide an understanding of the contribution of the normal modes to the complex signals measured using the Percussion Device.

Terahertz spectroscopy and solid-state density functional theory calculation of anthracene: Effect of dispersion force on the vibrational modes

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

Zhang, Feng; Tominaga, Keisuke, E-mail: atmyh@ntu.edu.tw, E-mail: tominaga@kobe-u.ca.jp, E-mail: junichi.nishizawa@hanken.jp; Hayashi, Michitoshi, E-mail: atmyh@ntu.edu.tw, E-mail: tominaga@kobe-u.ca.jp, E-mail: junichi.nishizawa@hanken.jp

2014-05-07

The phonon modes of molecular crystals in the terahertz frequency region often feature delicately coupled inter- and intra-molecular vibrations. Recent advances in density functional theory such as DFT-D{sup *} have enabled accurate frequency calculation. However, the nature of normal modes has not been quantitatively discussed against experimental criteria such as isotope shift (IS) and correlation field splitting (CFS). Here, we report an analytical mode-decoupling method that allows for the decomposition of a normal mode of interest into intermolecular translation, libration, and intramolecular vibrational motions. We show an application of this method using the crystalline anthracene system as an example. Themore » relationship between the experimentally obtained IS and the IS obtained by PBE-D{sup *} simulation indicates that two distinctive regions exist. Region I is associated with a pure intermolecular translation, whereas region II features coupled intramolecular vibrations that are further coupled by a weak intermolecular translation. We find that the PBE-D{sup *} data show excellent agreement with the experimental data in terms of IS and CFS in region II; however, PBE-D{sup *} produces significant deviations in IS in region I where strong coupling between inter- and intra-molecular vibrations contributes to normal modes. The result of this analysis is expected to facilitate future improvement of DFT-D{sup *}.« less

A new algorithm for construction of coarse-grained sites of large biomolecules.

PubMed

Li, Min; Zhang, John Z H; Xia, Fei

2016-04-05

The development of coarse-grained (CG) models for large biomolecules remains a challenge in multiscale simulations, including a rigorous definition of CG representations for them. In this work, we proposed a new stepwise optimization imposed with the boundary-constraint (SOBC) algorithm to construct the CG sites of large biomolecules, based on the s cheme of essential dynamics CG. By means of SOBC, we can rigorously derive the CG representations of biomolecules with less computational cost. The SOBC is particularly efficient for the CG definition of large systems with thousands of residues. The resulted CG sites can be parameterized as a CG model using the normal mode analysis based fluctuation matching method. Through normal mode analysis, the obtained modes of CG model can accurately reflect the functionally related slow motions of biomolecules. The SOBC algorithm can be used for the construction of CG sites of large biomolecules such as F-actin and for the study of mechanical properties of biomaterials. © 2015 Wiley Periodicals, Inc.

Stiffness-generated rigid-body mode shapes for Lanczos eigensolution with SUPORT DOF by way of a MSC/NASTRAN DMAP alter

NASA Technical Reports Server (NTRS)

Abdallah, Ayman A.; Barnett, Alan R.; Widrick, Timothy W.; Manella, Richard T.; Miller, Robert P.

1994-01-01

When using all MSC/NASTRAN eigensolution methods except Lanczos, the analyst can replace the coupled system rigid-body modes calculated within DMAP module READ with mass orthogonalized and normalized rigid-body modes generated from the system stiffness. This option is invoked by defining MSC/NASTRAN r-set degrees of freedom via the SUPORT bulk data card. The newly calculated modes are required if the rigid-body modes calculated by the eigensolver are not 'clean' due to numerical roundoffs in the solution. When performing transient structural dynamic load analysis, the numerical roundoffs can result in inaccurate rigid-body accelerations which affect steady-state responses. Unfortunately, when using the Lanczos method and defining r-set degrees of freedom, the rigid-body modes calculated within DMAP module REIGL are retained. To overcome this limitation and to allow MSC/NASTRAN to handle SUPORT degrees of freedom identically for all eigensolvers, a DMAP Alter has been written which replaces Lanczos-calculated rigid-body modes with stiffness-generated rigid-body modes. The newly generated rigid-body modes are normalized with respect to the system mass and orthogonalized using the Gram-Schmidt technique. This algorithm has been implemented as an enhancement to an existing coupled loads methodology.

Attitude analysis of the Earth Radiation Budget Satellite (ERBS) yaw turn anomaly

NASA Technical Reports Server (NTRS)

Kronenwetter, J.; Phenneger, M.; Weaver, William L.

1988-01-01

The July 2 Earth Radiation Budget Satellite (ERBS) hydrazine thruster-controlled yaw inversion maneuver resulted in a 2.1 deg/sec attitude spin. This mode continued for 150 minutes until the spacecraft was inertially despun using the hydrazine thrusters. The spacecraft remained in a low-rate Y-axis spin of .06 deg/sec for 3 hours until the B-DOT control mode was activated. After 5 hours in this mode, the spacecraft Y-axis was aligned to the orbit normal, and the spacecraft was commanded to the mission mode of attitude control. This work presents the experience of real-time attitude determination support following analysis using the playback telemetry tape recorded for 7 hours from the start of the attitude control anomaly.

Low order models for uncertainty quantification in acoustic propagation problems

NASA Astrophysics Data System (ADS)

Millet, Christophe

2016-11-01

Long-range sound propagation problems are characterized by both a large number of length scales and a large number of normal modes. In the atmosphere, these modes are confined within waveguides causing the sound to propagate through multiple paths to the receiver. For uncertain atmospheres, the modes are described as random variables. Concise mathematical models and analysis reveal fundamental limitations in classical projection techniques due to different manifestations of the fact that modes that carry small variance can have important effects on the large variance modes. In the present study, we propose a systematic strategy for obtaining statistically accurate low order models. The normal modes are sorted in decreasing Sobol indices using asymptotic expansions, and the relevant modes are extracted using a modified iterative Krylov-based method. The statistics of acoustic signals are computed by decomposing the original pulse into a truncated sum of modal pulses that can be described by a stationary phase method. As the low-order acoustic model preserves the overall structure of waveforms under perturbations of the atmosphere, it can be applied to uncertainty quantification. The result of this study is a new algorithm which applies on the entire phase space of acoustic fields.

Determination of low-frequency normal modes and structure coefficients using optimal sequence stacking method and autoregressive method in frequency domain

NASA Astrophysics Data System (ADS)

Majstorovic, J.; Rosat, S.; Lambotte, S.; Rogister, Y. J. G.

2017-12-01

Although there are numerous studies about 3D density Earth model, building an accurate one is still an engaging challenge. One procedure to refine global 3D Earth density models is based on unambiguous measurements of Earth's normal mode eigenfrequencies. To have unbiased eigenfrequency measurements one needs to deal with a variety of time records quality and especially different noise sources, while standard approaches usually include signal processing methods such as Fourier transform. Here we present estimate of complex eigenfrequencies and structure coefficients for several modes below 1 mHz (0S2, 2S1, etc.). Our analysis is performed in three steps. The first step includes the use of stacking methods to enhance specific modes of interest above the observed noise level. Out of three trials the optimal sequence estimation turned out to be the foremost compared to the spherical harmonic stacking method and receiver strip method. In the second step we apply an autoregressive method in the frequency domain to estimate complex eigenfrequencies of target modes. In the third step we apply the phasor walkout method to test and confirm our eigenfrequencies. Before conducting an analysis of time records, we evaluate how the station distribution and noise levels impact the estimate of eigenfrequencies and structure coefficients by using synthetic seismograms calculated for a 3D realistic Earth model, which includes Earth's ellipticity and lateral heterogeneity. Synthetic seismograms are computed by means of normal mode summation using self-coupling and cross-coupling of modes up to 1 mHz. Eventually, the methods tested on synthetic data are applied to long-period seismometer and superconducting gravimeter data recorded after six mega-earthquakes of magnitude greater than 8.3. Hence, we propose new estimates of structure coefficients dependent on the density variations.

New type of synchronization of oscillators with hard excitation

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

Kovaleva, M. A., E-mail: margo.kovaleva@gmail.com; Manevich, L. I., E-mail: manevichleonid3@gmail.com; Pilipchuk, V. N.

2013-08-15

It is shown that stable limiting cycles corresponding to nonlinear beats with complete energy exchange between oscillators can exist in a system of two weakly coupled active oscillators (generators). The oscillatory regime of this type, which implements a new type of synchronization in an active system, is an alternative to the well-studied synchronization in a regime close to a nonlinear normal mode. In this case, the ranges of dissipative parameters corresponding to different types of synchronization do not intersect. The analytic description of attractors revealed in analysis is based on the concept of limiting phase trajectories, which was developed earliermore » by one of the authors for conservative systems. A transition (in the parametric space) from the complete energy exchange between oscillators to predominant localization of energy in one of the oscillators can be naturally described using this concept. The localized normal mode is an attractor in the range of parameters in which neither the limiting phase trajectory nor any of the collective normal modes is an attractor.« less

Effects of thermal noise on the transitional dynamics of an inextensible elastic filament in stagnation flow.

PubMed

Deng, Mingge; Grinberg, Leopold; Caswell, Bruce; Karniadakis, George Em

2015-06-28

We investigate the dynamics of a single inextensible elastic filament subject to anisotropic friction in a viscous stagnation-point flow, by employing both a continuum model represented by Langevin type stochastic partial differential equations (SPDEs) and a dissipative particle dynamics (DPD) method. Unlike previous works, the filament is free to rotate and the tension along the filament is determined by the local inextensible constraint. The kinematics of the filament is recorded and studied with normal modes analysis. The results show that the filament displays an instability induced by negative tension, which is analogous to Euler buckling of a beam. Symmetry breaking of normal modes dynamics and stretch-coil transitions are observed above the threshold of the buckling instability point. Furthermore, both temporal and spatial noise are amplified resulting from the interaction of thermal fluctuations and nonlinear filament dynamics. Specifically, the spatial noise is amplified with even normal modes being excited due to symmetry breaking, while the temporal noise is amplified with increasing time correlation length and variance.

NASTRAN applications to aircraft propulsion systems

NASA Technical Reports Server (NTRS)

White, J. L.; Beste, D. L.

1975-01-01

The use of NASTRAN in propulsion system structural integration analysis is described. Computer support programs for modeling, substructuring, and plotting analysis results are discussed. Requirements on interface information and data exchange by participants in a NASTRAN substructure analysis are given. Static and normal modes vibration analysis results are given with comparison to test and other analytical results.

Modal coupling procedures adapted to NASTRAN analysis of the 1/8-scale shuttle structural dynamics model. Volume 1: Technical report

NASA Technical Reports Server (NTRS)

Zalesak, J.

1975-01-01

A dynamic substructuring analysis, utilizing the component modes technique, of the 1/8 scale space shuttle orbiter finite element model is presented. The analysis was accomplished in 3 phases, using NASTRAN RIGID FORMAT 3, with appropriate Alters, on the IBM 360-370. The orbiter was divided into 5 substructures, each of which was reduced to interface degrees of freedom and generalized normal modes. The reduced substructures were coupled to yield the first 23 symmetric free-free orbiter modes, and the eigenvectors in the original grid point degree of freedom lineup were recovered. A comparison was made with an analysis which was performed with the same model using the direct coordinate elimination approach. Eigenvalues were extracted using the inverse power method.

Design of a linear projector for use with the normal modes of the GLAS 4th order GCM

NASA Technical Reports Server (NTRS)

Bloom, S. C.

1984-01-01

The design of a linear projector for use with the normal modes of a model of atmospheric circulation is discussed. A central element in any normal mode initialization scheme is the process by which a set of data fields - winds, temperatures or geopotentials, and surface pressures - are expressed ("projected') in terms of the coefficients of a model's normal modes. This process is completely analogous to the Fourier decomposition of a single field (indeed a FFT applied in the zonal direction is a part of the process). Complete separability in all three spatial dimensions is assumed. The basis functions for the modal expansion are given. An important feature of the normal modes is their coupling of the structures of different fields, thus a coefficient in a normal mode expansion would contain both mass and momentum information.

An analysis of the number of parking bays and checkout counters for a supermarket using SAS simulation studio

NASA Astrophysics Data System (ADS)

Kar, Leow Soo

2014-07-01

Two important factors that influence customer satisfaction in large supermarkets or hypermarkets are adequate parking facilities and short waiting times at the checkout counters. This paper describes the simulation analysis of a large supermarket to determine the optimal levels of these two factors. SAS Simulation Studio is used to model a large supermarket in a shopping mall with car park facility. In order to make the simulation model more realistic, a number of complexities are introduced into the model. For example, arrival patterns of customers vary with the time of the day (morning, afternoon and evening) and with the day of the week (weekdays or weekends), the transport mode of arriving customers (by car or other means), the mode of payment (cash or credit card), customer shopping pattern (leisurely, normal, exact) or choice of checkout counters (normal or express). In this study, we focus on 2 important components of the simulation model, namely the parking area, the normal and express checkout counters. The parking area is modeled using a Resource Pool block where one resource unit represents one parking bay. A customer arriving by car seizes a unit of the resource from the Pool block (parks car) and only releases it when he exits the system. Cars arriving when the Resource Pool is empty (no more parking bays) leave without entering the system. The normal and express checkouts are represented by Server blocks with appropriate service time distributions. As a case study, a supermarket in a shopping mall with a limited number of parking bays in Bangsar was chosen for this research. Empirical data on arrival patterns, arrival modes, payment modes, shopping patterns, service times of the checkout counters were collected and analyzed to validate the model. Sensitivity analysis was also performed with different simulation scenarios to identify the parameters for the optimal number the parking spaces and checkout counters.

Cortical Thinning in Network-Associated Regions in Cognitively Normal and Below-Normal Range Schizophrenia

PubMed Central

Pinnock, Farena; Parlar, Melissa; Hawco, Colin; Hanford, Lindsay; Hall, Geoffrey B.

2017-01-01

This study assessed whether cortical thickness across the brain and regionally in terms of the default mode, salience, and central executive networks differentiates schizophrenia patients and healthy controls with normal range or below-normal range cognitive performance. Cognitive normality was defined using the MATRICS Consensus Cognitive Battery (MCCB) composite score (T = 50 ± 10) and structural magnetic resonance imaging was used to generate cortical thickness data. Whole brain analysis revealed that cognitively normal range controls (n = 39) had greater cortical thickness than both cognitively normal (n = 17) and below-normal range (n = 49) patients. Cognitively normal controls also demonstrated greater thickness than patients in regions associated with the default mode and salience, but not central executive networks. No differences on any thickness measure were found between cognitively normal range and below-normal range controls (n = 24) or between cognitively normal and below-normal range patients. In addition, structural covariance between network regions was high and similar across subgroups. Positive and negative symptom severity did not correlate with thickness values. Cortical thinning across the brain and regionally in relation to the default and salience networks may index shared aspects of the psychotic psychopathology that defines schizophrenia with no relation to cognitive impairment. PMID:28348889

IN SITU SOLID-PHASE EXTRACTION AND ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY, FULL-SCAN MODE

EPA Science Inventory

Fragrance materials, such as synthetic musks in aqueous samples, are normally analyzed by GC/MS in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of 1-L samples. A 1-L sample, however, usually provides too little ana...

ON-SITE SOLID PHRASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY, FULL-SCAN MODE

EPA Science Inventory

Fragrance materials, such as synthetic musks in aqueous samples, are normally analyzed by GC/MS in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. A I -L sample, however, usually provides too little ana...

ON-SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY IN THE FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

Drive Train Normal Modes Analysis for the ERDA/NASA 100-Kilowatt Wind Turbine Generator

NASA Technical Reports Server (NTRS)

Sullivan, T. L.; Miller, D. R.; Spera, D. A.

1977-01-01

Natural frequencies, as a function of power were determined using a finite element model. Operating conditions investigated were operation with a resistive electrical load and operation synchronized to an electrical utility grid. The influence of certain drive train components on frequencies and mode shapes is shown. An approximate method for obtaining drive train natural frequencies is presented.

Inelastic neutron scattering spectrum of cyclotrimethylenetrinitramine: a comparison with solid-state electronic structure calculations.

PubMed

Ciezak, Jennifer A; Trevino, S F

2006-04-20

Solid-state geometry optimizations and corresponding normal-mode analysis of the widely used energetic material cyclotrimethylenetrinitramine (RDX) were performed using density functional theory with both the generalized gradient approximation (BLYP and BP functionals) and the local density approximation (PWC and VWN functionals). The structural results were found to be in good agreement with experimental neutron diffraction data and previously reported calculations based on the isolated-molecule approximation. The vibrational inelastic neutron scattering (INS) spectrum of polycrystalline RDX was measured and compared with simulated INS constructed from the solid-state calculations. The vibrational frequencies calculated from the solid-state methods had average deviations of 10 cm(-1) or less, whereas previously published frequencies based on an isolated-molecule approximation had deviations of 65 cm(-1) or less, illustrating the importance of including crystalline forces. On the basis of the calculations and analysis, it was possible to assign the normal modes and symmetries, which agree well with previous assignments. Four possible "doorway modes" were found in the energy range defined by the lattice modes, which were all found to contain fundamental contributions from rotation of the nitro groups.

Effect of Pressure Anisotropy on the m = 1 Small Wavelength Modes in Z-Pinches

NASA Astrophysics Data System (ADS)

Faghihi, M.

1987-05-01

A generalization of Freidberg's perpendicular MHD model is used to investigate the effect of pressure anisotropy on the small wavelength internal kink (m = 1) mode instability in a Z-Pinch. A normal mode analysis of perturbed motion of an incompressible, collisionless and cylindrical plasma is performed. The stability criterion is (rΣB2)' <= 0, where Σ = 1 - (P|| - P⊥)/B2. It cannot be fulfilled without violation of the fire hose stability condition Σ >= 0.

Modeling guided wave excitation in plates with surface mounted piezoelectric elements: coupled physics and normal mode expansion

NASA Astrophysics Data System (ADS)

Ren, Baiyang; Lissenden, Cliff J.

2018-04-01

Guided waves have been extensively studied and widely used for structural health monitoring because of their large volumetric coverage and good sensitivity to defects. Effectively and preferentially exciting a desired wave mode having good sensitivity to a certain defect is of great practical importance. Piezoelectric discs and plates are the most common types of surface-mounted transducers for guided wave excitation and reception. Their geometry strongly influences the proportioning between excited modes as well as the total power of the excited modes. It is highly desirable to predominantly excite the selected mode while the total transduction power is maximized. In this work, a fully coupled multi-physics finite element analysis, which incorporates the driving circuit, the piezoelectric element and the wave guide, is combined with the normal mode expansion method to study both the mode tuning and total wave power. The excitation of circular crested waves in an aluminum plate with circular piezoelectric discs is numerically studied for different disc and adhesive thicknesses. Additionally, the excitation of plane waves in an aluminum plate, using a stripe piezoelectric element is studied both numerically and experimentally. It is difficult to achieve predominant single mode excitation as well as maximum power transmission simultaneously, especially for higher order modes. However, guidelines for designing the geometry of piezoelectric elements for optimal mode excitation are recommended.

Micromagnetic modal analysis of spin-transfer-driven ferromagnetic resonance of individual nanomagnets

NASA Astrophysics Data System (ADS)

Torres, L.; Finocchio, G.; Lopez-Diaz, L.; Martinez, E.; Carpentieri, M.; Consolo, G.; Azzerboni, B.

2007-05-01

In a recent investigation Sankey et al. [Phys. Rev. Lett. 96, 227601 (2006)] demonstrated a technique for measuring spin-transfer-driven ferromagnetic resonance in individual ellipsoidal PyCu nanomagnets as small as 30×90×5.5nm3. In the present work, these experiments are analyzed by means of full micromagnetic modeling finding quantitative agreement and enlightening the spatial distribution of the normal modes found in the experiment. The magnetic parameter set used in the computations is obtained by fitting static magnetoresistance measurements. The temperature effect is also included together with all the nonuniform contributions to the effective field as the magnetostatic coupling and the Ampere field. The polarization function of Slonczewski [J. Magn. Magn. Mater. 159, L1 (1996)] is used including its spatial and angular dependences. Experimental spin-transfer-driven ferromagnetic resonance spectra are reproduced using the same currents as in the experiment. The use of full micromagnetic modeling allows us to further investigate the spatial dependence of the modes. The dependence of the normal mode frequency on the dc and the external field together with a comparison to the normal modes induced by a microwave current is also addressed.

Computational aspects of the nonlinear normal mode initialization of the GLAS 4th order GCM

NASA Technical Reports Server (NTRS)

Navon, I. M.; Bloom, S. C.; Takacs, L.

1984-01-01

Using the normal modes of the GLAS 4th Order Model, a Machenhauer nonlinear normal mode initialization (NLNMI) was carried out for the external vertical mode using the GLAS 4th Order shallow water equations model for an equivalent depth corresponding to that associated with the external vertical mode. A simple procedure was devised which was directed at identifying computational modes by following the rate of increase of BAL sub M, the partial (with respect to the zonal wavenumber m) sum of squares of the time change of the normal mode coefficients (for fixed vertical mode index) varying over the latitude index L of symmetric or antisymmetric gravity waves. A working algorithm is presented which speeds up the convergence of the iterative Machenhauer NLNMI. A 24 h integration using the NLNMI state was carried out using both Matsuno and leap-frog time-integration schemes; these runs were then compared to a 24 h integration starting from a non-initialized state. The maximal impact of the nonlinear normal mode initialization was found to occur 6-10 hours after the initial time.

Independent Orbiter Assessment (IOA): Analysis of the active thermal control subsystem

NASA Technical Reports Server (NTRS)

Sinclair, S. K.; Parkman, W. E.

1987-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical (PCIs) items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Active Thermal Control Subsystem (ATCS) are documented. The major purpose of the ATCS is to remove the heat, generated during normal Shuttle operations from the Orbiter systems and subsystems. The four major components of the ATCS contributing to the heat removal are: Freon Coolant Loops; Radiator and Flow Control Assembly; Flash Evaporator System; and Ammonia Boiler System. In order to perform the analysis, the IOA process utilized available ATCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 310 failure modes analyzed, 101 were determined to be PCIs.

Anharmonic Normal Mode Analysis of Elastic Network Model Improves the Modeling of Atomic Fluctuations in Protein Crystal Structures

PubMed Central

Zheng, Wenjun

2010-01-01

Abstract Protein conformational dynamics, despite its significant anharmonicity, has been widely explored by normal mode analysis (NMA) based on atomic or coarse-grained potential functions. To account for the anharmonic aspects of protein dynamics, this study proposes, and has performed, an anharmonic NMA (ANMA) based on the Cα-only elastic network models, which assume elastic interactions between pairs of residues whose Cα atoms or heavy atoms are within a cutoff distance. The key step of ANMA is to sample an anharmonic potential function along the directions of eigenvectors of the lowest normal modes to determine the mean-squared fluctuations along these directions. ANMA was evaluated based on the modeling of anisotropic displacement parameters (ADPs) from a list of 83 high-resolution protein crystal structures. Significant improvement was found in the modeling of ADPs by ANMA compared with standard NMA. Further improvement in the modeling of ADPs is attained if the interactions between a protein and its crystalline environment are taken into account. In addition, this study has determined the optimal cutoff distances for ADP modeling based on elastic network models, and these agree well with the peaks of the statistical distributions of distances between Cα atoms or heavy atoms derived from a large set of protein crystal structures. PMID:20550915

High-Frequency Normal Mode Propagation in Aluminum Cylinders

USGS Publications Warehouse

Lee, Myung W.; Waite, William F.

2009-01-01

Acoustic measurements made using compressional-wave (P-wave) and shear-wave (S-wave) transducers in aluminum cylinders reveal waveform features with high amplitudes and with velocities that depend on the feature's dominant frequency. In a given waveform, high-frequency features generally arrive earlier than low-frequency features, typical for normal mode propagation. To analyze these waveforms, the elastic equation is solved in a cylindrical coordinate system for the high-frequency case in which the acoustic wavelength is small compared to the cylinder geometry, and the surrounding medium is air. Dispersive P- and S-wave normal mode propagations are predicted to exist, but owing to complex interference patterns inside a cylinder, the phase and group velocities are not smooth functions of frequency. To assess the normal mode group velocities and relative amplitudes, approximate dispersion relations are derived using Bessel functions. The utility of the normal mode theory and approximations from a theoretical and experimental standpoint are demonstrated by showing how the sequence of P- and S-wave normal mode arrivals can vary between samples of different size, and how fundamental normal modes can be mistaken for the faster, but significantly smaller amplitude, P- and S-body waves from which P- and S-wave speeds are calculated.

An efficient and numerically stable procedure for generating sextic force fields in normal mode coordinates

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

Sibaev, M.; Crittenden, D. L., E-mail: deborah.crittenden@canterbury.ac.nz

In this paper, we outline a general, scalable, and black-box approach for calculating high-order strongly coupled force fields in rectilinear normal mode coordinates, based upon constructing low order expansions in curvilinear coordinates with naturally limited mode-mode coupling, and then transforming between coordinate sets analytically. The optimal balance between accuracy and efficiency is achieved by transforming from 3 mode representation quartic force fields in curvilinear normal mode coordinates to 4 mode representation sextic force fields in rectilinear normal modes. Using this reduced mode-representation strategy introduces an error of only 1 cm{sup −1} in fundamental frequencies, on average, across a sizable testmore » set of molecules. We demonstrate that if it is feasible to generate an initial semi-quartic force field in curvilinear normal mode coordinates from ab initio data, then the subsequent coordinate transformation procedure will be relatively fast with modest memory demands. This procedure facilitates solving the nuclear vibrational problem, as all required integrals can be evaluated analytically. Our coordinate transformation code is implemented within the extensible PyPES library program package, at http://sourceforge.net/projects/pypes-lib-ext/.« less

Guided-mode interactions in thin films with surface corrugation

NASA Astrophysics Data System (ADS)

Seshadri, S. R.

1994-12-01

The guided modes in a thin-film planar dielectric waveguide sandwiched between a cover and a substrate (two different dielectrics) are considered. The interface between the cover and the film has a smooth corrugation in the longitudinal direction. For weak corrugations, the guided-mode interactions are investigated using the expansion in terms of ideal normal modes. A corresponding treament is given for the not-so-weak corrugations using the expansion in terms of local normal modes. The coupling coefficients are evaluated and reduced to simple forms. The theories are specialized for the treatment of contradirectional coupling between two guided modes taking place selectively in the neighborhood of the Bragg frequency. The coupled-mode equations governing the contradirectional interaction obtained from the local normal mode expansion procedure, in the limit of weak periodic corrugations, are identical to those deduced directly using the ideal normal mode expansion technique. The treatments for both the transverse electric and the transvers magnetic modes are included.

Operations analysis (study 2.1). Contingency analysis. [of failure modes anticipated during space shuttle upper stage planning

NASA Technical Reports Server (NTRS)

1974-01-01

Future operational concepts for the space transportation system were studied in terms of space shuttle upper stage failure contingencies possible during deployment, retrieval, or space servicing of automated satellite programs. Problems anticipated during mission planning were isolated using a modified 'fault tree' technique, normally used in safety analyses. A comprehensive space servicing hazard analysis is presented which classifies possible failure modes under the catagories of catastrophic collision, failure to rendezvous and dock, servicing failure, and failure to undock. The failure contingencies defined are to be taken into account during design of the upper stage.

Survey of the Frequency Dependent Latitudinal Distribution of the Fast Magnetosonic Wave Mode from Van Allen Probes Electric and Magnetic Field Instrument and Integrated Science Waveform Receiver Plasma Wave Analysis

NASA Technical Reports Server (NTRS)

Boardsen, Scott A.; Hospodarsky, George B.; Kletzing, Craig A.; Engebretson, Mark J.; Pfaff, Robert F.; Wygant, John R.; Kurth, William S.; Averkamp, Terrance F.; Bounds, Scott R.; Green, Jim L.;

Estimation of splitting functions from Earth's normal mode spectra using the neighbourhood algorithm

NASA Astrophysics Data System (ADS)

Pachhai, Surya; Tkalčić, Hrvoje; Masters, Guy

2016-01-01

The inverse problem for Earth structure from normal mode data is strongly non-linear and can be inherently non-unique. Traditionally, the inversion is linearized by taking partial derivatives of the complex spectra with respect to the model parameters (i.e. structure coefficients), and solved in an iterative fashion. This method requires that the earthquake source model is known. However, the release of energy in large earthquakes used for the analysis of Earth's normal modes is not simple. A point source approximation is often inadequate, and a more complete account of energy release at the source is required. In addition, many earthquakes are required for the solution to be insensitive to the initial constraints and regularization. In contrast to an iterative approach, the autoregressive linear inversion technique conveniently avoids the need for earthquake source parameters, but it also requires a number of events to achieve full convergence when a single event does not excite all singlets well. To build on previous improvements, we develop a technique to estimate structure coefficients (and consequently, the splitting functions) using a derivative-free parameter search, known as neighbourhood algorithm (NA). We implement an efficient forward method derived using the autoregresssion of receiver strips, and this allows us to search over a multiplicity of structure coefficients in a relatively short time. After demonstrating feasibility of the use of NA in synthetic cases, we apply it to observations of the inner core sensitive mode 13S2. The splitting function of this mode is dominated by spherical harmonic degree 2 axisymmetric structure and is consistent with the results obtained from the autoregressive linear inversion. The sensitivity analysis of multiple events confirms the importance of the Bolivia, 1994 earthquake. When this event is used in the analysis, as little as two events are sufficient to constrain the splitting functions of 13S2 mode. Apart from not requiring the knowledge of earthquake source, the newly developed technique provides an approximate uncertainty measure of the structure coefficients and allows us to control the type of structure solved for, for example to establish if elastic structure is sufficient.

An approach to detect afterslips in giant earthquakes in the normal-mode frequency band

NASA Astrophysics Data System (ADS)

Tanimoto, Toshiro; Ji, Chen; Igarashi, Mitsutsugu

2012-08-01

An approach to detect afterslips in the source process of giant earthquakes is presented in the normal-mode frequency band (0.3-2.0 mHz). The method is designed to avoid a potential systematic bias problem in the determination of earthquake moment by a typical normal-mode approach. The source of bias is the uncertainties in Q (modal attenuation parameter) which varies by up to about ±10 per cent among published studies. A choice of Q values within this range affects amplitudes in synthetic seismograms significantly if a long time-series of about 5-7 d is used for analysis. We present an alternative time-domain approach that can reduce this problem by focusing on a shorter time span with a length of about 1 d. Application of this technique to four recent giant earthquakes is presented: (1) the Tohoku, Japan, earthquake of 2011 March 11, (2) the 2010 Maule, Chile earthquake, (3) the 2004 Sumatra-Andaman earthquake and (4) the Solomon earthquake of 2007 April 1. The Global Centroid Moment Tensor (GCMT) solution for the Tohoku earthquake explains the normal-mode frequency band quite well. The analysis for the 2010 Chile earthquake indicates that the moment is about 7-10 per cent higher than the moment determined by its GCMT solution but further analysis shows that there is little evidence of afterslip; the deviation in moment can be explained by an increase of the dip angle from 18° in the GCMT solution to 19°. This may be a simple trade-off problem between the moment and dip angle but it may also be due to a deeper centroid in the normal-mode frequency band data, as a deeper source could have steeper dip angle due to changes in geometry of the Benioff zone. For the 2004 Sumatra-Andaman earthquake, the five point-source solution by Tsai et al. explains most of the signals but a sixth point-source with long duration improves the fit to the normal-mode frequency band data. The 2007 Solomon earthquake shows that the high-frequency part of our analysis (above 1 mHz) is compatible with the GCMT solution but the low-frequency part requires afterslip to explain the increasing amplitude ratios towards lower frequency. The required slip has the moment about 19 per cent of the GCMT solution and the rise time of 260 s. The total moment of these earthquakes are 5.31 × 1022 N m (Tohoku), (1.86-1.96) × 1022 N m (Chile), 1.33 × 1023 N m (Sumatra) and 1.86 × 1021 N m (Solomon). The moment magnitudes are 9.08, 8.78-8.79, 9.35 and 8.11, respectively, using Kanamori's original formula between the moment and the moment magnitude. However, the trade-off problem between the moment and dip angle can modify these estimates for moment up to about 40-50 per cent and the corresponding magnitude ±0.1.

Strain partitioning and deformation mode analysis of the normal faults at Red Mountain, Birmingham, Alabama

NASA Astrophysics Data System (ADS)

Wu, Schuman

1989-12-01

In a low-temperature environment, the thin-section scale rock-deformation mode is primarily a function of confining pressure and total strain at geological strain rates. A deformation mode diagram is constructed from published experimental data by plotting the deformation mode on a graph of total strain versus the confining pressure. Four deformation modes are shown on the diagram: extensional fracturing, mesoscopic faulting, incipient faulting, and uniform flow. By determining the total strain and the deformation mode of a naturally deformed sample, the confining pressure and hence the depth at which the rock was deformed can be evaluated. The method is applied to normal faults exposed on the gently dipping southeast limb of the Birmingham anticlinorium in the Red Mountain expressway cut in Birmingham, Alabama. Samples of the Ordovician Chickamauga Limestone within and adjacent to the faults contain brittle structures, including mesoscopic faults and veins, and ductile deformation features including calcite twins, intergranular and transgranular pressure solution, and deformed burrows. During compaction, a vertical shortening of about 45 to 80% in shale is indicated by deformed burrows and relative compaction of shale to burrows, about 6% in limestone by stylolites. The normal faults formed after the Ordovician rocks were consolidated because the faults and associated veins truncate the deformed burrows and stylolites, which truncate the calcite cement. A total strain of 2.0% was caused by mesoscopic faults during normal faulting. A later homogenous deformation, indicated by the calcite twins in veins, cement and fossil fragments, has its major principal shortening strain in the dip direction at a low angle (about 22°) to bedding. The strain magnitude is about 2.6%. By locating the observed data on the deformation mode diagram, it is found that the normal faulting characterized by brittle deformation occurred under low confining pressure (< 18 MPa) at shallow depth (< 800 m), and the homogenous horizontal compression characterized by uniform flow occurred under higher confining pressure (at least 60 MPa) at greater depth (> 2.5 km).

Redistribution of carbonyl stretch mode energy in isolated and solvated N-methylacetamide: kinetic energy spectral density analyses.

PubMed

Jeon, Jonggu; Cho, Minhaeng

2011-12-07

The vibrational energy transfer from the excited carbonyl stretch mode in N-deuterated N-methylacetamide (NMA-d), both in isolation and in a heavy water cluster, is studied with nonequilibrium molecular dynamics (NEMD) simulations, employing a quantum mechanical/molecular mechanical (QM∕MM) force field at the semiempirical PM3 level. The nonequilibrium ensemble of vibrationally excited NMA-d is prepared by perturbing the positions and velocities of the carbonyl C and O atoms and its NEMD trajectories are obtained with a leap-frog algorithm properly modified for the initial perturbation. In addition to the time-domain analysis of the kinetic and potential energies, a novel method for the spectral analysis of the atomic kinetic energies is developed, in terms of the spectral density of kinetic energy, which provides the time-dependent changes of the frequency-resolved kinetic energies without the complications of normal mode analysis at every MD time step. Due to the QM description of the solute electronic structure, the couplings among the normal modes are captured more realistically than with classical force fields. The energy transfer in the isolated NMA-d is found to proceed first from the carbonyl bond to other modes with time scales of 3 ps or less, and then among the other modes over 3-21 ps. In the solvated NMA-d, most of the excess energy is first transferred to other intramolecular modes within 5 ps, which is subsequently dissipated to solvent with 7-19 ps time scales. The contribution of the direct energy transfer from the carbonyl bond to solvent was only 5% with ~7 ps time scale. Solvent reorganization that leads to destabilization of the electrostatic interactions is found to be crucial in the long time relaxation of the excess energy, while the water intramolecular modes do not contribute significantly. Detailed mode-specific energy transfer pathways are deduced for the isolated and solvated NMA-d and they show that the energy transfer in NMA-d is a highly cooperative process among the intramolecular modes and there is no single dominant pathway with more than 30% of transient contribution. © 2011 American Institute of Physics

Fast Eigensolver for Computing 3D Earth's Normal Modes

NASA Astrophysics Data System (ADS)

Shi, J.; De Hoop, M. V.; Li, R.; Xi, Y.; Saad, Y.

2017-12-01

We present a novel parallel computational approach to compute Earth's normal modes. We discretize Earth via an unstructured tetrahedral mesh and apply the continuous Galerkin finite element method to the elasto-gravitational system. To resolve the eigenvalue pollution issue, following the analysis separating the seismic point spectrum, we utilize explicitly a representation of the displacement for describing the oscillations of the non-seismic modes in the fluid outer core. Effectively, we separate out the essential spectrum which is naturally related to the Brunt-Väisälä frequency. We introduce two Lanczos approaches with polynomial and rational filtering for solving this generalized eigenvalue problem in prescribed intervals. The polynomial filtering technique only accesses the matrix pair through matrix-vector products and is an ideal candidate for solving three-dimensional large-scale eigenvalue problems. The matrix-free scheme allows us to deal with fluid separation and self-gravitation in an efficient way, while the standard shift-and-invert method typically needs an explicit shifted matrix and its factorization. The rational filtering method converges much faster than the standard shift-and-invert procedure when computing all the eigenvalues inside an interval. Both two Lanczos approaches solve for the internal eigenvalues extremely accurately, comparing with the standard eigensolver. In our computational experiments, we compare our results with the radial earth model benchmark, and visualize the normal modes using vector plots to illustrate the properties of the displacements in different modes.

Exact mode volume and Purcell factor of open optical systems

NASA Astrophysics Data System (ADS)

Muljarov, E. A.; Langbein, W.

2016-12-01

The Purcell factor quantifies the change of the radiative decay of a dipole in an electromagnetic environment relative to free space. Designing this factor is at the heart of photonics technology, striving to develop ever smaller or less lossy optical resonators. The Purcell factor can be expressed using the electromagnetic eigenmodes of the resonators, introducing the notion of a mode volume for each mode. This approach allows an analytic treatment, reducing the Purcell factor and other observables to sums over eigenmode resonances. Calculating the mode volumes requires a correct normalization of the modes. We introduce an exact normalization of modes, not relying on perfectly matched layers. We present an analytic theory of the Purcell effect based on this exact mode normalization and the resulting effective mode volume. We use a homogeneous dielectric sphere in vacuum, which is analytically solvable, to exemplify these findings. We furthermore verify the applicability of the normalization to numerically determined modes of a finite dielectric cylinder.

Anharmonic vibrational spectra and mode-mode couplings analysis of 2-aminopyridine

NASA Astrophysics Data System (ADS)

Faizan, Mohd; Alam, Mohammad Jane; Afroz, Ziya; Bhat, Sheeraz Ahmad; Ahmad, Shabbir

2018-01-01

Vibrational spectra of 2-aminopyridine (2AP) have been analyzed using the vibrational self-consistence field theory (VSCF), correlated corrected vibrational self-consistence field theory (CC-VSCF) and vibrational perturbation theory (VPT2) at B3LYP/6-311G(d,p) framework. The mode-mode couplings affect the vibrational frequencies and intensities. The coupling integrals between pairs of normal modes have been obtained on the basis of quartic force field (2MR-QFF) approximation. The overtone and combination bands are also assigned in the FTIR spectrum with the help of anharmonic calculation at VPT2 method. A statistical analysis of deviations shows that estimated anharmonic frequencies are closer to the experiment over harmonic approximation. Furthermore, the anharmonic correction has also been carried out for the dimeric structure of 2AP. The fundamental vibration bands have been assigned on the basis of potential energy distribution (PED) and visual look over the animated modes. Other important molecular properties such as frontier molecular orbitals and molecular electrostatics potential mapping have also been analyzed.

Mode I stress intensity factors of slanted cracks in plates

NASA Astrophysics Data System (ADS)

Ismail, Al Emran; Ghazali, Mohd Zubir Mohd; Nor, Nik Hisyamudin Muhd

2017-01-01

This paper presents the roles of slanted cracks on the stress intensity factors (SIF) under mode I tension and bending loading. Based on the literature survey, lack of solution of SIFs of slanted cracks in plain strain plates are available. In this work, the cracks are modelled numerically using ANSYS finite element program. There are two important parameters such as slanted angles and relative crack length. SIFs at the crack tips are calculated according to domain integral method. Before the model is further used, it is validated with the existing model. It is found that the present model is well agreed with the previous model. According to finite element analysis, there are not only mode I SIFs produced but also mode II. As expected the SIFs increased as the relative crack length increased. However, when slanted angles are introduced (slightly higher than normal crack), the SIFs increased. Once the angles are further increased, the SIFs decreased gradually however they are still higher than the SIFs of normal cracks. For mode II SIFs, higher the slanted angels higher the SIFs. This is due to the fact that when the cracks are slanted, the cracked plates are not only failed due to mode I but a combination between both modes I and II.

Non-normality and classification of amplification mechanisms in stability and resolvent analysis

NASA Astrophysics Data System (ADS)

Symon, Sean; Rosenberg, Kevin; Dawson, Scott T. M.; McKeon, Beverley J.

2018-05-01

Eigenspectra and pseudospectra of the mean-linearized Navier-Stokes operator are used to characterize amplification mechanisms in laminar and turbulent flows in which linear mechanisms are important. Success of mean flow (linear) stability analysis for a particular frequency is shown to depend on whether two scalar measures of non-normality agree: (1) the product between the resolvent norm and the distance from the imaginary axis to the closest eigenvalue and (2) the inverse of the inner product between the most amplified resolvent forcing and response modes. If they agree, the resolvent operator can be rewritten in its dyadic representation to reveal that the adjoint and forward stability modes are proportional to the forcing and response resolvent modes at that frequency. Hence the real parts of the eigenvalues are important since they are responsible for resonant amplification and the resolvent operator is low rank when the eigenvalues are sufficiently separated in the spectrum. If the amplification is pseudoresonant, then resolvent analysis is more suitable to understand the origin of observed flow structures. Two test cases are studied: low Reynolds number cylinder flow and turbulent channel flow. The first deals mainly with resonant mechanisms, hence the success of both classical and mean stability analysis with respect to predicting the critical Reynolds number and global frequency of the saturated flow. Both scalar measures of non-normality agree for the base and mean flows, and the region where the forcing and response modes overlap scales with the length of the recirculation bubble. In the case of turbulent channel flow, structures result from both resonant and pseudoresonant mechanisms, suggesting that both are necessary elements to sustain turbulence. Mean shear is exploited most efficiently by stationary disturbances while bounds on the pseudospectra illustrate how pseudoresonance is responsible for the most amplified disturbances at spatial wavenumbers and temporal frequencies corresponding to well-known turbulent structures. Some implications for flow control are discussed.

Estimation of Characteristics of Echo Envelope Using RF Echo Signal from the Liver

NASA Astrophysics Data System (ADS)

Yamaguchi, Tadashi; Hachiya, Hiroyuki; Kamiyama, Naohisa; Ikeda, Kazuki; Moriyasu, Norifumi

2001-05-01

To realize quantitative diagnosis of liver cirrhosis, we have been analyzing the probability density function (PDF) of echo amplitude using B-mode images. However, the B-mode image is affected by the various signal and image processing techniques used in the diagnosis equipment, so a detailed and quantitative analysis is very difficult. In this paper, we analyze the PDF of echo amplitude using RF echo signal and B-mode images of normal and cirrhotic livers, and compare both results to examine the validity of the RF echo signal.

The vibrational spectroscopic studies and molecular property analysis of L-Phenylalanine using quantum chemical method

NASA Astrophysics Data System (ADS)

Borah, Mukunda Madhab; Devi, Th. Gomti

2017-05-01

In the present work, L-phenylalanine is studied using the experimental and theoretical methods. The spectral characterization of the molecule has been done using Raman, FTIR, Hartee-Fock(HF), density functional theory (DFT) and vibrational energy distribution analysis (VEDA) calculation. The optimization of the molecule has been studied using basis set HF/6-31G(d,p) and B3LYP/6-31G(d,p) for Hartree Fock and density functional theory calculation. The complete vibrational assignment of the molecule in monomer and dimer states have been attempted. The potential energy distribution and normal mode analysis are also carried out to determine the contributions of bond oscillators in each normal mode. The molecular geometry, HOMO-LUMO energy gap, molecular hardness (η), ionization energy (IE), electron affinity (EA), total energy and dipole moment were determined from the calculated data. The observed experimental and the scaled theoretical results are compared and found to be in good agreement. The vibrational assignment of molecule in different dimer states has also been done using SERS data and better correlated Raman peaks are observed as compare to normal Raman technique.

Ultrasonic guided wave propagation across waveguide transitions: energy transfer and mode conversion.

PubMed

Puthillath, Padmakumar; Galan, Jose M; Ren, Baiyang; Lissenden, Cliff J; Rose, Joseph L

2013-05-01

Ultrasonic guided wave inspection of structures containing adhesively bonded joints requires an understanding of the interaction of guided waves with geometric and material discontinuities or transitions in the waveguide. Such interactions result in mode conversion with energy being partitioned among the reflected and transmitted modes. The step transition between an aluminum layer and an aluminum-adhesive-aluminum multi-layer waveguide is analyzed as a model structure. Dispersion analysis enables assessment of (i) synchronism through dispersion curve overlap and (ii) wavestructure correlation. Mode-pairs in the multi-layer waveguide are defined relative to a prescribed mode in a single layer as being synchronized and having nearly perfect wavestructure matching. Only a limited number of mode-pairs exist, and each has a unique frequency range. A hybrid model based on semi-analytical finite elements and the normal mode expansion is implemented to assess mode conversion at a step transition in a waveguide. The model results indicate that synchronism and wavestructure matching is associated with energy transfer through the step transition, and that the energy of an incident wave mode in a single layer is transmitted almost entirely to the associated mode-pair, where one exists. This analysis guides the selection of incident modes that convert into transmitted modes and improve adhesive joint inspection with ultrasonic guided waves.

A mechanism for magnetospheric substorms

NASA Technical Reports Server (NTRS)

Erickson, G. M.; Heinemann, M.

1994-01-01

Energy-principle analysis performed on two-dimensional, self-consistent solutions for magnetospheric convection indicates that the magnetosphere is unstable to isobaric (yet still frozen-in) fluctuations of plasma-sheet flux tubes. Normally, pdV work associated with compression maintains stability of the inward/outward oscillating normal mode. However, if Earth's ionosphere can provide sufficient mass flux, isobaric expansion of flux tubes can occur. The growth of a field-aligned potential drop in the near-Earth, midnight portion of the plasma sheet, associated with upward field-aligned currents responsible for the Harang discontinuity, redistributes plasma along field lines in a manner that destabilizes the normal mode. The growth of this unstable mode results in an out-of-equilibrium situation near the inner edge. When this occurs over a downtail extent comparable to the half-thickness of the plasma sheet, collapse ensues and forces thinning of the plasma sheet whereby conditions favorable to reconnection occur. This scenario for substorm onset is consistent with observed upward fluxes of ions, parallel potential drops, and observations of substorm onset. These observations include near Earth onset, pseudobreakups, the substorm current wedge, and local variations of plasma-sheet thickness.

Functional Dynamics of PDZ Binding Domains: A Normal-Mode Analysis

PubMed Central

De Los Rios, Paolo; Cecconi, Fabio; Pretre, Anna; Dietler, Giovanni; Michielin, Olivier; Piazza, Francesco; Juanico, Brice

2005-01-01

Postsynaptic density-95/disks large/zonula occludens-1 (PDZ) domains are relatively small (80–120 residues) protein binding modules central in the organization of receptor clusters and in the association of cellular proteins. Their main function is to bind C-terminals of selected proteins that are recognized through specific amino acids in their carboxyl end. Binding is associated with a deformation of the PDZ native structure and is responsible for dynamical changes in regions not in direct contact with the target. We investigate how this deformation is related to the harmonic dynamics of the PDZ structure and show that one low-frequency collective normal mode, characterized by the concerted movements of different secondary structures, is involved in the binding process. Our results suggest that even minimal structural changes are responsible for communication between distant regions of the protein, in agreement with recent NMR experiments. Thus, PDZ domains are a very clear example of how collective normal modes are able to characterize the relation between function and dynamics of proteins, and to provide indications on the precursors of binding/unbinding events. PMID:15821164

Effects of Thermal Noise on the Transitional Dynamics of an Inextensible Elastic Filament in Stagnation Flow

PubMed Central

Deng, Mingge; Grinberg, Leopold; Caswell, Bruce

2015-01-01

We investigate the dynamics of a single inextensible elastic filament subject to anisotropic friction in a viscous stagnation-point flow, by employing both a continuum model represented by Langevin type stochastic partial differential equations (SPDEs) and a Dissipative Particle Dynamics (DPD) method. Unlike previous works1, the filament is free to rotate and the tension along the filament is determined by the local inextensible constraint. The kinematics of the filament is recorded and studied with normal modes analysis. The results show that the filament displays an instability induced by negative tension, which is analogous to Euler buckling of a beam. Symmetry breaking of normal modes dynamics and stretch-coil transitions are observed above the threshold of the buckling instability point. Furthermore, both temporal and spatial noise are amplified resulting from the interaction of thermal fluctuations and nonlinear filament dynamics. Specifically, the spatial noise is amplified with even normal modes being excited due to symmetry breaking, while the temporal noise is amplified with increasing time correlation length and variance. PMID:26023834

A new method to real-normalize measured complex modes

NASA Technical Reports Server (NTRS)

Wei, Max L.; Allemang, Randall J.; Zhang, Qiang; Brown, David L.

1987-01-01

A time domain subspace iteration technique is presented to compute a set of normal modes from the measured complex modes. By using the proposed method, a large number of physical coordinates are reduced to a smaller number of model or principal coordinates. Subspace free decay time responses are computed using properly scaled complex modal vectors. Companion matrix for the general case of nonproportional damping is then derived in the selected vector subspace. Subspace normal modes are obtained through eigenvalue solution of the (M sub N) sup -1 (K sub N) matrix and transformed back to the physical coordinates to get a set of normal modes. A numerical example is presented to demonstrate the outlined theory.

Normal-Mode Analysis of Circular DNA at the Base-Pair Level. 2. Large-Scale Configurational Transformation of a Naturally Curved Molecule.

PubMed

Matsumoto, Atsushi; Tobias, Irwin; Olson, Wilma K

2005-01-01

Fine structural and energetic details embedded in the DNA base sequence, such as intrinsic curvature, are important to the packaging and processing of the genetic material. Here we investigate the internal dynamics of a 200 bp closed circular molecule with natural curvature using a newly developed normal-mode treatment of DNA in terms of neighboring base-pair "step" parameters. The intrinsic curvature of the DNA is described by a 10 bp repeating pattern of bending distortions at successive base-pair steps. We vary the degree of intrinsic curvature and the superhelical stress on the molecule and consider the normal-mode fluctuations of both the circle and the stable figure-8 configuration under conditions where the energies of the two states are similar. To extract the properties due solely to curvature, we ignore other important features of the double helix, such as the extensibility of the chain, the anisotropy of local bending, and the coupling of step parameters. We compare the computed normal modes of the curved DNA model with the corresponding dynamical features of a covalently closed duplex of the same chain length constructed from naturally straight DNA and with the theoretically predicted dynamical properties of a naturally circular, inextensible elastic rod, i.e., an O-ring. The cyclic molecules with intrinsic curvature are found to be more deformable under superhelical stress than rings formed from naturally straight DNA. As superhelical stress is accumulated in the DNA, the frequency, i.e., energy, of the dominant bending mode decreases in value, and if the imposed stress is sufficiently large, a global configurational rearrangement of the circle to the figure-8 form takes place. We combine energy minimization with normal-mode calculations of the two states to decipher the configurational pathway between the two states. We also describe and make use of a general analytical treatment of the thermal fluctuations of an elastic rod to characterize the motions of the minicircle as a whole from knowledge of the full set of normal modes. The remarkable agreement between computed and theoretically predicted values of the average deviation and dispersion of the writhe of the circular configuration adds to the reliability in the computational approach. Application of the new formalism to the computed modes of the figure-8 provides insights into macromolecular motions which are beyond the scope of current theoretical treatments.

Information processing of visually presented picture and word stimuli by young hearing-impaired and normal-hearing children.

PubMed

Kelly, R R; Tomlison-Keasey, C

1976-12-01

Eleven hearing-impaired children and 11 normal-hearing children (mean = four years 11 months) were visually presented familiar items in either picture or word form. Subjects were asked to recognize the stimuli they had seen from cue cards consisting of pictures or words. They were then asked to recall the sequence of stimuli by arranging the cue cards selected. The hearing-impaired group and normal-hearing subjects performed differently with the picture/picture (P/P) and word/word (W/W) modes in the recognition phase. The hearing impaired performed equally well with both modes (P/P and W/W), while the normal hearing did significantly better on the P/P mode. Furthermore, the normal-hearing group showed no difference in processing like modes (P/P and W/W) when compared to unlike modes (W/P and P/W). In contrast, the hearing-impaired subjects did better on like modes. The results were interpreted, in part, as supporting the position that young normal-hearing children dual code their visual information better than hearing-impaired children.

Collective dynamics of lysozyme in water: terahertz absorption spectroscopy and comparison with theory.

PubMed

Xu, Jing; Plaxco, Kevin W; Allen, S James

2006-11-30

To directly measure the low-frequency vibrational modes of proteins in biologically relevant water environment rather than previously explored dry or slightly hydrated phase, we have developed a broadband terahertz spectrometer suitable for strongly attenuating protein solutions. Radiation is provided by harmonic multipliers (up to 0.21 THz), a Gunn oscillator (at 0.139 THz), and the UCSB free-electron lasers (up to 4.8 THz). Our spectrometer combines these intense sources with a sensitive cryogenic detector and a variable path length sample cell to detect radiation after it is attenuated by more than 7 orders of magnitudes by the aqueous sample. Using this spectrometer, we have measured the molar extinction of solvated lysozyme between 0.075 and 3.72 THz (2.5-124 cm(-1)), and we made direct comparison to several published theoretical models based on molecular dynamics simulations and normal-mode analysis. We confirm the existence of dense, overlapping normal modes in the terahertz frequency range. Our observed spectrum, while in rough qualitative agreement with these models, differs in detail. Further, we observe a low-frequency cutoff in terahertz dynamics between 0.2 and 0.3 THz, and we see no evidence of a predicted normal mode at approximately 0.09 THz for the protein.

NMSim web server: integrated approach for normal mode-based geometric simulations of biologically relevant conformational transitions in proteins.

PubMed

Krüger, Dennis M; Ahmed, Aqeel; Gohlke, Holger

2012-07-01

The NMSim web server implements a three-step approach for multiscale modeling of protein conformational changes. First, the protein structure is coarse-grained using the FIRST software. Second, a rigid cluster normal-mode analysis provides low-frequency normal modes. Third, these modes are used to extend the recently introduced idea of constrained geometric simulations by biasing backbone motions of the protein, whereas side chain motions are biased toward favorable rotamer states (NMSim). The generated structures are iteratively corrected regarding steric clashes and stereochemical constraint violations. The approach allows performing three simulation types: unbiased exploration of conformational space; pathway generation by a targeted simulation; and radius of gyration-guided simulation. On a data set of proteins with experimentally observed conformational changes, the NMSim approach has been shown to be a computationally efficient alternative to molecular dynamics simulations for conformational sampling of proteins. The generated conformations and pathways of conformational transitions can serve as input to docking approaches or more sophisticated sampling techniques. The web server output is a trajectory of generated conformations, Jmol representations of the coarse-graining and a subset of the trajectory and data plots of structural analyses. The NMSim webserver, accessible at http://www.nmsim.de, is free and open to all users with no login requirement.

Mean flow generation mechanism by inertial waves and normal modes

NASA Astrophysics Data System (ADS)

Will, Andreas; Ghasemi, Abouzar

2016-04-01

The mean flow generation mechanism by nonlinearity of the inertial normal modes and inertial wave beams in a rotating annular cavity with longitudinally librating walls in stable regime is discussed. Inertial normal modes (standing waves) are excited when libration frequency matches eigenfrequencies of the system. Inertial wave beams are produced by Ekman pumping and suction in a rotating cylinder and form periodic orbits or periodic ray trajectories at selected frequencies. Inertial wave beams emerge as concentrated shear layers in a librating annular cavity, while normal modes appear as global recirculation cells. Both (inertial wave beam and mode) are helical and thus intrinsically non-linear flow structures. No second mode or wave is necessary for non-linearity. We considered the low order normal modes (1,1), (2,1) and (2,2) which are expected to be excited in the planetary objects and investigate the mean flow generation mechanism using two independent solutions: 1) analytical solution (Borcia 2012) and 2) the wave component of the flow (ω0 component) obtained from the direct numerical simulation (DNS). It is well known that a retrograde bulk mean flow is generated by the Ekman boundary layer and E1/4-Stewartson layer close to the outer cylinder side wall due to libration. At and around the normal mode resonant frequencies we found additionally a prograde azimuthal mean flow (Inertial Normal Mode Mean Flow: INMMF) in the bulk of the fluid. The fluid in the bulk is in geostrophic balance in the absence of the inertial normal modes. However, when INMMF is excited, we found that the geostrophic balance does not hold in the region occupied by INMMF. We hypothesize that INMMF is generated by the nonlinearity of the normal modes or by second order effects. Expanding the velocity {V}(u_r,u_θ,u_z) and pressure (p) in a power series in ɛ (libration amplitude), the Navier-Stokes equations are segregated into the linear and nonlinear parts at orders ɛ1 and ɛ^2, respectively. The former is used to find the analytical solution of the normal modes (Borcia 2012). Plugging two independent solutions into the latter we investigate the generation mechanism of INMMF. We found R1^1=overbar{partial_z(u_r1 u_z^1)}, R2^1=overbar{partial_r(u_r1 u_r^1)} as source terms responsible for the generation of INMMF. The helical structure of the inertial waves causes the nonlinear terms R1 and R2 to be nonzero, contributing to the generation of INMMF. We used u_ra and u_za obtained from the analytical solution (Borcia 2012) and computed the source terms R1a and R2a and found a structural correspondence with the corresponding field computed from the DNS solution for the three normal modes investigated. The sum of R11 and R21 exhibits a good structural correspondence with INMMF. Interestingly, INMMF magnitude depends on the inertial wave beams and normal modes. For instance we found that INMMF is generated more efficiently for the libration frequency ω=1.58, although the resonant frequency is predicted by the analytical solution to be at ω=1.576 (normal mode (2,1)). Separating the inertial wave beams from the flow field obtained by DNS, using the analytical normal mode solution, we explored the phase lag between inertial wave beams and normal mode. We inferred that the normal mode amplitude is high only if the phase lag between the inertial wave beam and the normal mode is predominantly positive. In this case a high amplitude INMMF amplitude can be found. This supports the hypothesis that the normal modes are generated by the inertial wave beam in analogy to resonant forcing in classical mechanics. Interestingly, the 'optimum' phase lag found is much smaller than π/2. {Acknowledgement:} This work is a part of the project "Mischung und Grundstromanregung durch propagierende Trgheitswellen: Theorie, Experiment und Simulation" supported by the German Science Foundation (DFG). We would like to thank M. Klein, U. Harlander, I. Borcia and E. Schaller for helpful discussions and invaluable contributions. {References:} Borcia, I. D. & Harlander, U. 2012 Inertial waves in a rotating annulus with inclined inner cylinder: comparing the spectrum of wave attractor frequency bands and the eigenspectrum in the limit of zero inclination. Theor. Comput. Fluid Dyn. 27, 397-413.

Independent Orbiter Assessment (IOA): Analysis of the displays and controls subsystem

NASA Technical Reports Server (NTRS)

Trahan, W. H.; Prust, E. E.

1987-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Displays and Controls (D and C) subsystem hardware. The function of the D and C hardware is to provide the crew with the monitor, command, and control capabilities required for management of all normal and contingency mission and flight operations. The D and C hardware for which failure modes analysis was performed consists of the following: Acceleration Indicator (G-METER); Head Up Display (HUD); Display Driver Unit (DDU); Alpha/Mach Indicator (AMI); Horizontal Situation Indicator (HSI); Attitude Director Indicator (ADI); Propellant Quantity Indicator (PQI); Surface Position Indicator (SPI); Altitude/Vertical Velocity Indicator (AVVI); Caution and Warning Assembly (CWA); Annunciator Control Assembly (ACA); Event Timer (ET); Mission Timer (MT); Interior Lighting; and Exterior Lighting. Each hardware item was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

Lattice dynamical and dielectric properties of L-amino acids

NASA Astrophysics Data System (ADS)

Tulip, P. R.; Clark, S. J.

2006-08-01

We present the results of ab initio calculations of the lattice dynamical and dielectric properties of the L-amino acids L-alanine, L-leucine, and L-isoleucine. Normal-mode frequencies and dielectric permittivity tensors are obtained using density-functional perturbation theory implemented within the plane-wave pseudopotential approximation. IR spectra are calculated and are used to analyze the effects of intermolecular interactions and zwitterionization upon the lattice dynamics. It is found that vibronic modes associated with the carboxy and amino functional groups undergo modification from their free-molecule values due to the presence of hydrogen bonds. The role of macroscopic electric fields set up by zone-center normal modes in the lattice dynamics is investigated by analysis of the Born effective charge. Calculated permittivity tensors are found to be greater than would be obtained by a naive use of the isolated molecular values, indicating the role of intermolecular interactions in increasing molecular polarizability.

The computational analysis and modelling of substitution effects on hydrolysis of formanilides in acidic aqueous solutions

NASA Astrophysics Data System (ADS)

Lukeš, Vladimír; Škorňa, Peter; Michalík, Martin; Klein, Erik

2017-11-01

Various para, meta and ortho substituted formanilides have been theoretically studied. For trans and cis-isomers of non-substituted formanilide, the calculated B3LYP vibration normal modes were analyzed. Substituent effect on the selected normal modes was described and the comparison with the available experimental data is presented. The calculated B3LYP proton affinities were correlated with Hammett constants, Fujita-Nishioka equation and the rate constants of the hydrolysis in 1 M HCl. Found linear dependences allow predictions of dissociation constants (pKBH+) and hydrolysis rate constants. Obtained results indicate that protonation of amide group may represent the rate determining step of acid catalyzed hydrolysis.

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

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

Yang, Xi; Huang, Xiaobiao

2016-05-13

Here, we propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. Finally, the method has been successfully demonstrated on the NSLS-II storage ring.

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

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

Yang, Xi; Huang, Xiaobiao

2016-08-01

We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. Furthermore, the fitting results are used for lattice correction. Our method has been successfully demonstrated on the NSLS-II storage ring.

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

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

Yang, Xi; Huang, Xiaobiao

2016-08-01

We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demonstrated on the NSLS-II storage ring.

Molecular structure, natural bond analysis, vibrational and electronic spectra, surface enhanced Raman scattering and Mulliken atomic charges of the normal modes of [Mn(DDTC)2] complex.

PubMed

Téllez S, Claudio A; Costa, Anilton C; Mondragón, M A; Ferreira, Glaucio B; Versiane, O; Rangel, J L; Lima, G Müller; Martin, A A

2016-12-05

Theoretical and experimental bands have been assigned for the Fourier Transform Infrared and Raman spectra of the bis(diethyldithiocarbamate)Mn(II) complex, [Mn(DDTC)2]. The calculations have been based on the DFT/B3LYP method, second derivative spectra and band deconvolution analysis. The UV-vis experimental spectra were measured in acetonitrile solution, and the calculated electronic spectrum was obtained using the TD/B3LYP method with 6-311G(d, p) basis set for all atoms. Charge transfer bands and those d-d spin forbidden were assigned in the UV-vis spectrum. The natural bond orbital analysis was carried out using the DFT/B3LYP method and the Mn(II) hybridization leading to the planar geometry of the framework was discussed. Surface enhanced Raman scattering (SERS) was also performed. Mulliken charges of the normal modes were obtained and related to the SERS enhanced bands. Copyright © 2016 Elsevier B.V. All rights reserved.

Structural dynamic model obtained from flight use with piloted simulation and handling qualities analysis

NASA Technical Reports Server (NTRS)

Powers, Bruce G.

1996-01-01

The ability to use flight data to determine an aircraft model with structural dynamic effects suitable for piloted simulation. and handling qualities analysis has been developed. This technique was demonstrated using SR-71 flight test data. For the SR-71 aircraft, the most significant structural response is the longitudinal first-bending mode. This mode was modeled as a second-order system, and the other higher order modes were modeled as a time delay. The distribution of the modal response at various fuselage locations was developed using a uniform beam solution, which can be calibrated using flight data. This approach was compared to the mode shape obtained from the ground vibration test, and the general form of the uniform beam solution was found to be a good representation of the mode shape in the areas of interest. To calibrate the solution, pitch-rate and normal-acceleration instrumentation is required for at least two locations. With the resulting structural model incorporated into the simulation, a good representation of the flight characteristics was provided for handling qualities analysis and piloted simulation.

Numerical Analysis of the Effects of Normalized Plasma Pressure on RMP ELM Suppression in DIII-D

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

Orlov, D. M.; Moyer, R.A.; Evans, T. E.

2010-01-01

The effect of normalized plasma pressure as characterized by normalized pressure parameter (beta(N)) on the suppression of edge localized modes (ELMs) using resonant magnetic perturbations (RMPs) is studied in low-collisionality (nu* <= 0.2) H-mode plasmas with low-triangularity ( = 0.25) and ITER similar shapes ( = 0.51). Experimental results have suggested that ELM suppression by RMPs requires a minimum threshold in plasma pressure as characterized by beta(N). The variations in the vacuum field topology with beta(N) due to safety factor profile and island overlap changes caused by variation of the Shafranov shift and pedestal bootstrap current are examined numerically withmore » the field line integration code TRIP3D. The results show very small differences in the vacuum field structure in terms of the Chirikov (magnetic island overlap) parameter, Poincare sections and field line loss fractions. These differences do not appear to explain the observed threshold in beta(N) for ELM suppression. Linear peeling-ballooning stability analysis with the ELITE code suggests that the ELMs which persist during the RMPs when beta(N) is below the observed threshold are not type I ELMs, because the pedestal conditions are deep within the stable regime for peeling-ballooning modes. These ELMs have similarities to type III ELMs or low density ELMs.« less

Helicon normal modes in Proto-MPEX

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

Piotrowicz, Pawel A.; Caneses, Juan F.; Green, David L.

Here, the Proto-MPEX helicon source has been operating in a high electron density 'helicon-mode'. Establishing plasma densities and magnetic field strengths under the antenna that allow for the formation of normal modes of the fast-wave are believed to be responsible for the 'helicon-mode'. A 2D finite-element full-wave model of the helicon antenna on Proto-MPEX is used to identify the fast-wave normal modes responsible for the steady-state electron density profile produced by the source. We also show through the simulation that in the regions of operation in which core power deposition is maximum the slow-wave does not deposit significant power besidesmore » directly under the antenna. In the case of a simulation where a normal mode is not excited significant edge power is deposited in the mirror region.« less

Helicon normal modes in Proto-MPEX

DOE PAGES

Piotrowicz, Pawel A.; Caneses, Juan F.; Green, David L.; ...

2018-05-22

Here, the Proto-MPEX helicon source has been operating in a high electron density 'helicon-mode'. Establishing plasma densities and magnetic field strengths under the antenna that allow for the formation of normal modes of the fast-wave are believed to be responsible for the 'helicon-mode'. A 2D finite-element full-wave model of the helicon antenna on Proto-MPEX is used to identify the fast-wave normal modes responsible for the steady-state electron density profile produced by the source. We also show through the simulation that in the regions of operation in which core power deposition is maximum the slow-wave does not deposit significant power besidesmore » directly under the antenna. In the case of a simulation where a normal mode is not excited significant edge power is deposited in the mirror region.« less

Digital computer program DF1758 fully coupled natural frequencies and mode shapes of a helicopter rotor blade

NASA Technical Reports Server (NTRS)

Bennett, R. L.

1975-01-01

The analytical techniques and computer program developed in the fully-coupled rotor vibration study are described. The rotor blade natural frequency and mode shape analysis was implemented in a digital computer program designated DF1758. The program computes collective, cyclic, and scissor modes for a single blade within a specified range of frequency for specified values of rotor RPM and collective angle. The analysis includes effects of blade twist, cg offset from reference axis, and shear center offset from reference axis. Coupled inplane, out-of-plane, and torsional vibrations are considered. Normalized displacements, shear forces and moments may be printed out and Calcomp plots of natural frequencies as a function of rotor RPM may be produced.

Conformational dynamics and ligand binding in the multi-domain protein PDC109.

PubMed

Kim, Hyun Jin; Choi, Moo Young; Kim, Hyung J; Llinás, Miguel

2010-02-18

PDC109 is a modular multi-domain protein with two fibronectin type II (Fn2) repeats joined by a linker. It plays a major role in bull sperm binding to the oviductal epithelium through its interactions with phosphorylcholines (PhCs), a head group of sperm cell membrane lipids. The crystal structure of the PDC109-PhC complex shows that each PhC binds to the corresponding Fn2 domain, while the two domains are on the same face of the protein. Long timescale explicit solvent molecular dynamics (MD) simulations of PDC109, in the presence and absence of PhC, suggest that PhC binding strongly correlates with the relative orientation of choline-phospholipid binding sites of the two Fn2 domains; unless the two domains tightly bind PhCs, they tend to change their relative orientation by deforming the flexible linker. The effective PDC109-PhC association constant of 28 M(-1), estimated from their potential of mean force is consistent with the experimental result. Principal component analysis of the long timescale MD simulations was compared to the significantly less expensive normal mode analysis of minimized structures. The comparison indicates that difference between relative domain motions of PDC109 with bound and unbound PhC is captured by the first principal component in the principal component analysis as well as the three lowest normal modes in the normal mode analysis. The present study illustrates the use of detailed MD simulations to clarify the energetics of specific ligand-domain interactions revealed by a static crystallographic model, as well as their influence on relative domain motions in a multi-domain protein.

Electromagnetically induced transparency in the case of elliptic polarization of interacting fields

NASA Astrophysics Data System (ADS)

Parshkov, Oleg M.

2018-04-01

The theoretical investigation results of disintegration effect of elliptic polarized shot probe pulses of electromagnetically induced transparency in the counterintuitive superposed elliptic polarized control field and in weak probe field approximation are presented. It is shown that this disintegration occurs because the probe field in the medium is the sum of two normal modes, which correspond to elliptic polarized pulses with different speeds of propagation. The polarization ellipses of normal modes have equal eccentricities and mutually perpendicular major axes. Major axis of polarization ellipse of one normal mode is parallel to polarization ellipse major axis of control field, and electric vector of this mode rotates in the opposite direction, than electric vector of the control field. The electric vector other normal mode rotates in the same direction that the control field electric vector. The normal mode speed of the first type aforementioned is less than that of the second type. The polarization characteristics of the normal mode depend uniquely on the polarization characteristics of elliptic polarized control field and remain changeless in the propagation process. The theoretical investigation is performed for Λ-scheme of degenerated quantum transitions between 3P0, 3P10 and 3P2 energy levels of 208Pb isotope.

Finite element normal mode analysis of resistance welding jointed of dissimilar plate hat structure

NASA Astrophysics Data System (ADS)

Nazri, N. A.; Sani, M. S. M.

2017-10-01

Structural joints offer connection between structural element (beam, plate, solid etc.) in order to build a whole assembled structure. The complex behaviour of connecting elements plays a valuable role in characteristics of dynamic such as natural frequencies and mode shapes. In automotive structures, the trustworthiness arrangement of the structure extremely depends on joints. In this paper, top hat structure is modelled and designed with spot welding joint using dissimilar materials which is mild steel 1010 and stainless steel 304, using finite element software. Different types of connector elements such as rigid body element (RBE2), welding joint element (CWELD), and bar element (CBAR) are applied to represent real connection between two dissimilar plates. Normal mode analysis is simulated with different types of joining element in order to determine modal properties. Natural frequencies using RBE2, CBAR and CWELD are compared to equivalent rigid body method. Connection that gives the lowest percentage error among these three will be selected as the most reliable joining for resistance spot weld. From the analysis, it is shown that CWELD is better compared to others in term of weld joining among dissimilar plate materials. It is expected that joint modelling of finite element plays significant role in structural dynamics.

Effects of intermode nonlinearity and intramode nonlinearity on modulation instability in randomly birefringent two-mode optical fibers

NASA Astrophysics Data System (ADS)

Li, Jin Hua; Xu, Hui; Sun, Ting Ting; Pei, Shi Xin; Ren, Hai Dong

2018-05-01

We analyze in detail the effects of the intermode nonlinearity (IEMN) and intramode nonlinearity (IRMN) on modulation instability (MI) in randomly birefringent two-mode optical fibers (RB-TMFs). In the anomalous dispersion regime, the MI gain enhances significantly as the IEMN and IRMN coefficients increases. In the normal dispersion regime, MI can be generated without the differential mode group delay (DMGD) effect, as long as the IEMN coefficient between two distinct modes is above a critical value, or the IRMN coefficient inside a mode is below a critical value. This critical IEMN (IRMN) coefficient depends strongly on the given IRMN (IEMN) coefficient and DMGD for a given nonlinear RB-TMF structure, and is independent on the input total power, the power ratio distribution and the group velocity dispersion (GVD) ratio between the two modes. On the other hand, in contrast to the MI band arising from the pure effect of DMGD in the normal dispersion regime, where MI vanishes after a critical total power, the generated MI band under the combined effects of IEMN and IRMN without DMGD exists for any total power and enhances with the total power. The MI analysis is verified numerically by launching perturbed continuous waves (CWs) with wave propagation method.

Application of Multiple Imputation for Missing Values in Three-Way Three-Mode Multi-Environment Trial Data

PubMed Central

Tian, Ting; McLachlan, Geoffrey J.; Dieters, Mark J.; Basford, Kaye E.

2015-01-01

It is a common occurrence in plant breeding programs to observe missing values in three-way three-mode multi-environment trial (MET) data. We proposed modifications of models for estimating missing observations for these data arrays, and developed a novel approach in terms of hierarchical clustering. Multiple imputation (MI) was used in four ways, multiple agglomerative hierarchical clustering, normal distribution model, normal regression model, and predictive mean match. The later three models used both Bayesian analysis and non-Bayesian analysis, while the first approach used a clustering procedure with randomly selected attributes and assigned real values from the nearest neighbour to the one with missing observations. Different proportions of data entries in six complete datasets were randomly selected to be missing and the MI methods were compared based on the efficiency and accuracy of estimating those values. The results indicated that the models using Bayesian analysis had slightly higher accuracy of estimation performance than those using non-Bayesian analysis but they were more time-consuming. However, the novel approach of multiple agglomerative hierarchical clustering demonstrated the overall best performances. PMID:26689369

Application of Multiple Imputation for Missing Values in Three-Way Three-Mode Multi-Environment Trial Data.

PubMed

Tian, Ting; McLachlan, Geoffrey J; Dieters, Mark J; Basford, Kaye E

2015-01-01

It is a common occurrence in plant breeding programs to observe missing values in three-way three-mode multi-environment trial (MET) data. We proposed modifications of models for estimating missing observations for these data arrays, and developed a novel approach in terms of hierarchical clustering. Multiple imputation (MI) was used in four ways, multiple agglomerative hierarchical clustering, normal distribution model, normal regression model, and predictive mean match. The later three models used both Bayesian analysis and non-Bayesian analysis, while the first approach used a clustering procedure with randomly selected attributes and assigned real values from the nearest neighbour to the one with missing observations. Different proportions of data entries in six complete datasets were randomly selected to be missing and the MI methods were compared based on the efficiency and accuracy of estimating those values. The results indicated that the models using Bayesian analysis had slightly higher accuracy of estimation performance than those using non-Bayesian analysis but they were more time-consuming. However, the novel approach of multiple agglomerative hierarchical clustering demonstrated the overall best performances.

Hybrid Electron Microscopy Normal Mode Analysis graphical interface and protocol.

PubMed

Sorzano, Carlos Oscar S; de la Rosa-Trevín, José Miguel; Tama, Florence; Jonić, Slavica

2014-11-01

This article presents an integral graphical interface to the Hybrid Electron Microscopy Normal Mode Analysis (HEMNMA) approach that was developed for capturing continuous motions of large macromolecular complexes from single-particle EM images. HEMNMA was shown to be a good approach to analyze multiple conformations of a macromolecular complex but it could not be widely used in the EM field due to a lack of an integral interface. In particular, its use required switching among different software sources as well as selecting modes for image analysis was difficult without the graphical interface. The graphical interface was thus developed to simplify the practical use of HEMNMA. It is implemented in the open-source software package Xmipp 3.1 (http://xmipp.cnb.csic.es) and only a small part of it relies on MATLAB that is accessible through the main interface. Such integration provides the user with an easy way to perform the analysis of macromolecular dynamics and forms a direct connection to the single-particle reconstruction process. A step-by-step HEMNMA protocol with the graphical interface is given in full details in Supplementary material. The graphical interface will be useful to experimentalists who are interested in studies of continuous conformational changes of macromolecular complexes beyond the modeling of continuous heterogeneity in single particle reconstruction. Copyright © 2014 Elsevier Inc. All rights reserved.

The dance of molecules: new dynamical perspectives on highly excited molecular vibrations.

PubMed

Kellman, Michael E; Tyng, Vivian

2007-04-01

At low energies, molecular vibrational motion is described by the normal modes model. This model breaks down at higher energy, with strong coupling between normal modes and onset of chaotic dynamics. New anharmonic modes are born in bifurcations, or branchings of the normal modes. Knowledge of these new modes is obtained through the window of frequency-domain spectroscopy, using techniques of nonlinear classical dynamics. It may soon be possible to "watch" molecular rearrangement reactions spectroscopically. Connections are being made with reaction rate theories, condensed phase systems, and motions of electrons in quantum dots.

A numerical investigation of head waves and leaky modes in fluid- filled boreholes.

USGS Publications Warehouse

Paillet, Frederick L.; Cheng, C.H.

1986-01-01

Although synthetic borehole seismograms can be computed for a wide range of borehole conditions, the physical nature of shear and compressional head waves in fluid-filled boreholes is poorly understood. Presents a series of numerical experiments designed to explain the physical mechanisms controlling head-wave propagation in boreholes. These calculations demonstrate the existence of compressional normal modes equivalent to shear normal modes, or pseudo-Rayleigh waves, with sequential cutoff frequencies spaced between the cutoff frequencies for the shear normal modes.-from Authors

Hereditary esophageal dysfunction in the Miniature Schnauzer dog.

PubMed

Cox, V S; Wallace, L J; Anderson, V E; Rushmer, R A

1980-03-01

Miniature Schnauzers maintained in a colony for 9 years were used to study the inheritance of esophageal dysfunction (canine achalasia, megaesophagus). All dogs were evaluated radiographically, using a barium swallow contrast technique which clearly distinguished normal and affected pups. At 4 to 6 months of age, all affected dogs had recovered clinically except one, and radiographic evidence of dysfunction was markedly diminished. None of the affected dogs required a special feeding regimen. Analysis of breeding pairs revealed a ratio of 9 affected/11 normal dogs when an affected male was mated with a normal female, and a 13/3 ratio was observed when two affected dogs were mated. These ratios were compatible with a simple autosomal dominant or a 60% penetrance autosomal-recessive mode of inheritance. Outbreeding to an affected Miniature Schnauzer/Poodle crossbred dog resulted in only two of 30 affected pups, indicating a polygenic mode of inheritance in outbred populations.

Mode shape analysis using a commercially available peak store video frame buffer

NASA Technical Reports Server (NTRS)

Snow, Walter L.; Childers, Brooks A.

1994-01-01

Time exposure photography, sometimes coupled with strobe illumination, is an accepted method for motion analysis that bypasses frame by frame analysis and resynthesis of data. Garden variety video cameras can now exploit this technique using a unique frame buffer that is a non-integrating memory that compares incoming data with that already stored. The device continuously outputs an analog video signal of the stored contents which can then be redigitized and analyzed using conventional equipment. Historically, photographic time exposures have been used to record the displacement envelope of harmonically oscillating structures to show mode shape. Mode shape analysis is crucial, for example, in aeroelastic testing of wind tunnel models. Aerodynamic, inertial, and elastic forces can couple together leading to catastrophic failure of a poorly designed aircraft. This paper will explore the usefulness of the peak store device as a videometric tool and in particular discuss methods for analyzing a targeted vibrating plate using the 'peak store' in conjunction with calibration methods familiar to the close-range videometry community. Results for the first three normal modes will be presented.

Mode shape analysis using a commercially available "peak-store" video frame buffer

NASA Astrophysics Data System (ADS)

Snow, Walter L.; Childers, Brooks A.

1994-10-01

Time exposure photography, sometimes coupled with strobe illumination, is an accepted method for motion analysis that bypasses frame by frame analysis and re synthesis of data. Garden variety video cameras can now exploit this technique using a unique frame buffer that is a non integrating memory that compares incoming data with that already stored. The device continuously outputs an analog video signal of the stored contents which can then be redigitized and analyzed using conventional equipment. Historically, photographic time exposures have been used to record the displacement envelope of harmonically oscillating structures to show mode shape. Mode shape analysis is crucial, for example, in aeroelastic testing of wind tunnel models. Aerodynamic, inertial, and elastic forces can couple together leading to catastrophic failure of a poorly designed aircraft. This paper will explore the usefulness of the peak store device as a videometric tool and in particular discuss methods for analyzing a targeted vibrating plate using the `peak store' in conjunction with calibration methods familiar to the close-range videometry community. Results for the first three normal modes will be presented.

Simultaneous chiral discrimination of multiple profens by cyclodextrin-modified capillary electrophoresis in normal and reversed polarity modes.

PubMed

La, Sookie; Kim, Jiyung; Kim, Jung-Han; Goto, Junichi; Kim, Kyoung-Rae

2003-08-01

Simultaneous enantioseparations of nine profens for their accurate chiral discrimination were achieved by capillary electrophoresis (CE) in the normal polarity (NP) mode with a single cyclodextrin (CD) system and in the reversed polarity (RP) mode with a dual CD system. The single CD system in the NP mode employed heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMbetaCD) added at 75 mM-100 mM 2-(N-morpholino)ethanesulfonic acid buffer (pH 6.0) as the optimum run buffer. The dual CD system operated in the RP mode used 30 mM TMbetaCD and 1.0% anionic carboxymethyl-beta-cyclodextrin dissolved in pH 3.0, 100 mM phosphoric acid-triethanolamine buffer containing 0.01% hexadimethrine bromide added to reverse the electroosmotic flow. Fairly good enantiomeric resolutions and the opposite enantiomer migration orders were achieved in the two modes. Relative migration times to internal standard under respective optimum conditions were characteristic of each enantiomer with good precision (< 2% relative standard deviation, RSD), thereby enabling to crosscheck the chemical identification of profens and also their accurate chiralities. The method linearity in the two modes was found to be adequate (r > or = 0.9991) for the chiral assay of the profens investigated. Simultaneous enantiomeric purity test of ibuprofen, ketoprofen and flurbiprofen in a mixture was feasible in a single analysis by the present method.

Correlating the vibrational spectra of structurally related molecules: A spectroscopic measure of similarity.

PubMed

Tao, Yunwen; Zou, Wenli; Cremer, Dieter; Kraka, Elfi

2018-03-05

Using catastrophe theory and the concept of a mutation path, an algorithm is developed that leads to the direct correlation of the normal vibrational modes of two structurally related molecules. The mutation path is defined by weighted incremental changes in mass and geometry of the molecules in question, which are successively applied to mutate a molecule into a structurally related molecule and thus continuously converting their normal vibrational spectra from one into the other. Correlation diagrams are generated that accurately relate the normal vibrational modes to each other by utilizing mode-mode overlap criteria and resolving allowed and avoided crossings of vibrational eigenstates. The limitations of normal mode correlation, however, foster the correlation of local vibrational modes, which offer a novel vibrational measure of similarity. It will be shown how this will open new avenues for chemical studies. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Crack Front Segmentation and Facet Coarsening in Mixed-Mode Fracture

NASA Astrophysics Data System (ADS)

Chen, Chih-Hung; Cambonie, Tristan; Lazarus, Veronique; Nicoli, Matteo; Pons, Antonio J.; Karma, Alain

2015-12-01

A planar crack generically segments into an array of "daughter cracks" shaped as tilted facets when loaded with both a tensile stress normal to the crack plane (mode I) and a shear stress parallel to the crack front (mode III). We investigate facet propagation and coarsening using in situ microscopy observations of fracture surfaces at different stages of quasistatic mixed-mode crack propagation and phase-field simulations. The results demonstrate that the bifurcation from propagating a planar to segmented crack front is strongly subcritical, reconciling previous theoretical predictions of linear stability analysis with experimental observations. They further show that facet coarsening is a self-similar process driven by a spatial period-doubling instability of facet arrays.

Broadband multiple responses of surface modes in quasicrystalline plasmonic structure

PubMed Central

Yuan, Haiming; Jiang, Xiangqian; Huang, Feng; Sun, Xiudong

2016-01-01

We numerically study the multiple excitation of surface modes in 2D photonic quasicrystal/metal/substrate structure. An improved rigorous coupled wave analysis method that can handle the quasicrystalline structure is presented. The quasicrystalline lattice, which refers to Penrose tiling in this paper, is generated by the cut-and-project method. The normal incidence spectrum presents a broadband multiple responses property. We find that the phase matching condition determines the excitation frequency for a given incident angle, while the depth of the reflection valley depends on the incident polarization. The modes will split into several sub-modes at oblique incidence, which give rise to the appearance of more responses on the spectrum. PMID:27492782

Normal modes of a small gamelan gong.

PubMed

Perrin, Robert; Elford, Daniel P; Chalmers, Luke; Swallowe, Gerry M; Moore, Thomas R; Hamdan, Sinin; Halkon, Benjamin J

2014-10-01

Studies have been made of the normal modes of a 20.7 cm diameter steel gamelan gong. A finite-element model has been constructed and its predictions for normal modes compared with experimental results obtained using electronic speckle pattern interferometry. Agreement was reasonable in view of the lack of precision in the manufacture of the instrument. The results agree with expectations for an axially symmetric system subject to small symmetry breaking. The extent to which the results obey Chladni's law is discussed. Comparison with vibrational and acoustical spectra enabled the identification of the small number of modes responsible for the sound output when played normally. Evidence of non-linear behavior was found, mainly in the form of subharmonics of true modes. Experiments using scanning laser Doppler vibrometry gave satisfactory agreement with the other methods.

Toothguide Trainer tests with color vision deficiency simulation monitor.

PubMed

Borbély, Judit; Varsányi, Balázs; Fejérdy, Pál; Hermann, Péter; Jakstat, Holger A

2010-01-01

The aim of this study was to evaluate whether simulated severe red and green color vision deficiency (CVD) influenced color matching results and to investigate whether training with Toothguide Trainer (TT) computer program enabled better color matching results. A total of 31 color normal dental students participated in the study. Every participant had to pass the Ishihara Test. Participants with a red/green color vision deficiency were excluded. A lecture on tooth color matching was given, and individual training with TT was performed. To measure the individual tooth color matching results in normal and color deficient display modes, the TT final exam was displayed on a calibrated monitor that served as a hardware-based method of simulating protanopy and deuteranopy. Data from the TT final exams were collected in normal and in severe red and green CVD-simulating monitor display modes. Color difference values for each participant in each display mode were computed (∑ΔE(ab)(*)), and the respective means and standard deviations were calculated. The Student's t-test was used in statistical evaluation. Participants made larger ΔE(ab)(*) errors in severe color vision deficient display modes than in the normal monitor mode. TT tests showed significant (p<0.05) difference in the tooth color matching results of severe green color vision deficiency simulation mode compared to normal vision mode. Students' shade matching results were significantly better after training (p=0.009). Computer-simulated severe color vision deficiency mode resulted in significantly worse color matching quality compared to normal color vision mode. Toothguide Trainer computer program improved color matching results. Copyright © 2010 Elsevier Ltd. All rights reserved.

Regularized quasinormal modes for plasmonic resonators and open cavities

NASA Astrophysics Data System (ADS)

Kamandar Dezfouli, Mohsen; Hughes, Stephen

2018-03-01

Optical mode theory and analysis of open cavities and plasmonic particles is an essential component of optical resonator physics, offering considerable insight and efficiency for connecting to classical and quantum optical properties such as the Purcell effect. However, obtaining the dissipative modes in normalized form for arbitrarily shaped open-cavity systems is notoriously difficult, often involving complex spatial integrations, even after performing the necessary full space solutions to Maxwell's equations. The formal solutions are termed quasinormal modes, which are known to diverge in space, and additional techniques are frequently required to obtain more accurate field representations in the far field. In this work, we introduce a finite-difference time-domain technique that can be used to obtain normalized quasinormal modes using a simple dipole-excitation source, and an inverse Green function technique, in real frequency space, without having to perform any spatial integrations. Moreover, we show how these modes are naturally regularized to ensure the correct field decay behavior in the far field, and thus can be used at any position within and outside the resonator. We term these modes "regularized quasinormal modes" and show the reliability and generality of the theory by studying the generalized Purcell factor of dipole emitters near metallic nanoresonators, hybrid devices with metal nanoparticles coupled to dielectric waveguides, as well as coupled cavity-waveguides in photonic crystals slabs. We also directly compare our results with full-dipole simulations of Maxwell's equations without any approximations, and show excellent agreement.

Anomalous waveforms observed in laboratory-formed gas hydrate-bearing and ice-bearing sediments

PubMed Central

Lee, Myung W.; Waite, William F.

2011-01-01

Acoustic transmission measurements of compressional, P, and shear, S, wave velocities rely on correctly identifying the P- and S-body wave arrivals in the measured waveform. In cylindrical samples for which the sample is much longer than the acoustic wavelength, these body waves can be obscured by high-amplitude waveform features arriving just after the relatively small-amplitude P-body wave. In this study, a normal mode approach is used to analyze this type of waveform, observed in sediment containing gas hydrate or ice. This analysis extends an existing normal-mode waveform propagation theory by including the effects of the confining medium surrounding the sample, and provides guidelines for estimating S-wave velocities from waveforms containing multiple large-amplitude arrivals. PMID:21476628

Upper-Tropospheric Synoptic-Scale Waves. Part II: Maintenance and Excitation of Quasi Modes.

NASA Astrophysics Data System (ADS)

Rivest, Chantal; Farrell, Brian F.

1992-11-01

In a preceding paper a simple dynamical model for the maintenance of upper-tropospheric waves was proposed: the upper-level Eady normal modes. In this paper it is shown that these modes have counterparts in basic states with positive tropospheric gradients of potential vorticity, and that these counterparts can be maintained and excited on time scales consistent with observations.In the presence of infinitesimal positive tropospheric gradients of potential vorticity, the upper-level normal-mode solutions no longer exist. That the normal-mode solution disappears when gradients are infinitesimal represents an apparent singularity and challenges the interpretation of upper-level synoptic-scale waves as related to the upper-level Eady normal modes. What happens to the upper-level modal solution in the presence of tropospheric gradients of potential vorticity is examined in a series of initial-value experiments. Our results show that they become slowly decaying quasi modes. Mathematically the quasi modes consist of a superposition of singular modes sharply peaked in the phase speed domain, and their decay proceeds as the modes interfere with one another. We repeat these experiments in basic states with a smooth tropopause in the presence of tropospheric and stratospheric gradients, and similar results are obtained.Following a previous study by Farrell, a class of near-optimal initial conditions for the excitation of upper-level waves is identified. The initial conditions consist of upper-tropospheric disturbances that lean against the shear. They strongly excite upper-level waves not only in the absence of tropospheric potential vorticity gradients, but also in their presence. This result is important mathematically since it suggests that quasi modes are as likely to emerge from favorably configured initial disturbances as true normal modes, although the excitation is followed by a slow decay.

Elementary dispersion analysis of some mimetic discretizations on triangular C-grids

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

Korn, P., E-mail: peter.korn@mpimet.mpg.de; Danilov, S.; A.M. Obukhov Institute of Atmospheric Physics, Moscow

2017-02-01

Spurious modes supported by triangular C-grids limit their application for modeling large-scale atmospheric and oceanic flows. Their behavior can be modified within a mimetic approach that generalizes the scalar product underlying the triangular C-grid discretization. The mimetic approach provides a discrete continuity equation which operates on an averaged combination of normal edge velocities instead of normal edge velocities proper. An elementary analysis of the wave dispersion of the new discretization for Poincaré, Rossby and Kelvin waves shows that, although spurious Poincaré modes are preserved, their frequency tends to zero in the limit of small wavenumbers, which removes the divergence noisemore » in this limit. However, the frequencies of spurious and physical modes become close on shorter scales indicating that spurious modes can be excited unless high-frequency short-scale motions are effectively filtered in numerical codes. We argue that filtering by viscous dissipation is more efficient in the mimetic approach than in the standard C-grid discretization. Lumping of mass matrices appearing with the velocity time derivative in the mimetic discretization only slightly reduces the accuracy of the wave dispersion and can be used in practice. Thus, the mimetic approach cures some difficulties of the traditional triangular C-grid discretization but may still need appropriately tuned viscosity to filter small scales and high frequencies in solutions of full primitive equations when these are excited by nonlinear dynamics.« less

Quantized mode of a leaky cavity

NASA Astrophysics Data System (ADS)

Dutra, S. M.; Nienhuis, G.

2000-12-01

We use Thomson's classical concept of mode of a leaky cavity to develop a quantum theory of cavity damping. This theory generalizes the conventional system-reservoir theory of high-Q cavity damping to arbitrary Q. The small system now consists of damped oscillators corresponding to the natural modes of the leaky cavity rather than undamped oscillators associated with the normal modes of a fictitious perfect cavity. The formalism unifies semiclassical Fox-Li modes and the normal modes traditionally used for quantization. It also lays the foundations for a full quantum description of excess noise. The connection with Siegman's semiclassical work is straightforward. In a wider context, this theory constitutes a radical departure from present models of dissipation in quantum mechanics: unlike conventional models, system and reservoir operators no longer commute with each other. This noncommutability is an unavoidable consequence of having to use natural cavity modes rather than normal modes of a fictitious perfect cavity.

The study on the nanomachining property and cutting model of single-crystal sapphire by atomic force microscopy.

PubMed

Huang, Jen-Ching; Weng, Yung-Jin

2014-01-01

This study focused on the nanomachining property and cutting model of single-crystal sapphire during nanomachining. The coated diamond probe is used to as a tool, and the atomic force microscopy (AFM) is as an experimental platform for nanomachining. To understand the effect of normal force on single-crystal sapphire machining, this study tested nano-line machining and nano-rectangular pattern machining at different normal force. In nano-line machining test, the experimental results showed that the normal force increased, the groove depth from nano-line machining also increased. And the trend is logarithmic type. In nano-rectangular pattern machining test, it is found when the normal force increases, the groove depth also increased, but rather the accumulation of small chips. This paper combined the blew by air blower, the cleaning by ultrasonic cleaning machine and using contact mode probe to scan the surface topology after nanomaching, and proposed the "criterion of nanomachining cutting model," in order to determine the cutting model of single-crystal sapphire in the nanomachining is ductile regime cutting model or brittle regime cutting model. After analysis, the single-crystal sapphire substrate is processed in small normal force during nano-linear machining; its cutting modes are ductile regime cutting model. In the nano-rectangular pattern machining, due to the impact of machined zones overlap, the cutting mode is converted into a brittle regime cutting model. © 2014 Wiley Periodicals, Inc.

An approach to the quantization of black hole quasi-normal modes

NASA Astrophysics Data System (ADS)

Pal, Soham; Rajeev, Karthik; Shankaranarayanan, S.

2015-07-01

In this work, we derive the asymptotic quasi-normal modes of a Banados-Teitelboim-Zanelli (BTZ) black hole using a quantum field theoretic Lagrangian. The BTZ black hole is a very popular system in the context of 2 + 1-dimensional quantum gravity. However, to our knowledge the quasi-normal modes of the BTZ black hole have been studied only in the classical domain. Here we show a way to quantize the quasi-normal modes of the BTZ black hole by mapping it to the Bateman-Feschbach-Tikochinsky oscillator and the Caldirola-Kanai oscillator. We have also discussed a couple of other black hole potentials to which this method can be applied.

An Investigation of the Neutral Cascade Muon Semileptonic Decay and its Observation at KTeV, Fermilab (in Portuguese)

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

Gomes, Ricardo Avelino

2005-07-01

The authors report an investigation of the semileptonic decay Ξ 0 → Σ + μ -more » $$\\bar{v}$$ μ. This decay was observed for the first time with nine identified events using the KTeV beam line and detector at Fermilab. The decay is normalized to the Ξ 0 beta decay mode and yields a value for the ratio of decay rates Γ(Ξ 0 → Σ 0 μ -$$\\bar{v}$$ μ)/Γ(Ξ 0 → Σ +e -$$\\bar{v}$$ e) of (1.8$$+0.7\\atop{-0.5}$$(stat.) ± 0.2(syst.)) x 10 -0 at the 68.27% confidence level, being the official measurement of KTeV Collaboration. They also used the dominant decay Ξ 0 → Γπ 0(Γ → pπ -) as normalization mode in an independent analysis which corroborated with the main result. In addition, a new measurement of the Ξ 0 → Σ + e -$$\\bar{v}$$ e branching ratio is presented, based on 1139 events and normalized to the Ξ 0 → Γπ 0(Γ → pπ -) decay mode. The results are in agreement with the SU(3) flavor symmetric quark model.« less

Seismic transmission operator reciprocity - II: impedance-operator symmetry via elastic lateral modes

NASA Astrophysics Data System (ADS)

Thomson, C. J.

2015-08-01

The properties of the overburden transmission response are of particular interest for the analysis of reflectivity illumination or blurring in seismic depth imaging. The first step to showing a transmission-operator reciprocity property is to identify the symmetry of the so-called displacement-to-traction operators. The latter are analogous to Dirichlet-to-Neumann operators and they may also be called impedance operators. Their symmetry is deduced here after development of a formal spectral or modal theory of lateral wavefunctions in a laterally heterogeneous generally anisotropic elastic medium. The elastic lateral modes are displacement-traction 6-vectors and they are built from two auxiliary 3-vector lateral-mode bases. These auxiliary modes arise from Hermitian and anti-Hermitian operators, so they have familiar properties such as orthogonality. There is no assumption of down/up symmetry of the elasticity tensor, but basic assumptions are made about the existence and completeness of the elastic modes. A point-symmetry property appears and plays a central role. The 6-vector elastic modes have a symplectic orthogonality property, which facilitates the development of modal expansions for 6-vector functions of the lateral coordinates when completeness is assumed. While the elastic modal theory is consistent with the laterally homogeneous case, numerical work would provide confidence that it is correct in general. An appendix contains an introductory overview of acoustic lateral modes that were studied by other authors, given from the perspective of this new work. A distinction is drawn between unit normalization of scalar auxiliary modes and a separate energy-flux normalization of 2-vector acoustic modes. Neither is crucial to the form of acoustic pressure-to-velocity or impedance operators. This statement carries over to the elastic case for the 3-vector auxiliary- and 6-vector elastic-mode normalizations. The modal theory is used to construct the kernel of the elastic displacement-to-traction or impedance operator. Symmetry properties of this operator are then deduced, which is the main goal of this paper. The implications of elastic impedance-operator symmetry and the symplectic property for the transmission and reflection responses of finite regions are described in a companion paper.

Causality analysis of leading singular value decomposition modes identifies rotor as the dominant driving normal mode in fibrillation

NASA Astrophysics Data System (ADS)

Biton, Yaacov; Rabinovitch, Avinoam; Braunstein, Doron; Aviram, Ira; Campbell, Katherine; Mironov, Sergey; Herron, Todd; Jalife, José; Berenfeld, Omer

2018-01-01

Cardiac fibrillation is a major clinical and societal burden. Rotors may drive fibrillation in many cases, but their role and patterns are often masked by complex propagation. We used Singular Value Decomposition (SVD), which ranks patterns of activation hierarchically, together with Wiener-Granger causality analysis (WGCA), which analyses direction of information among observations, to investigate the role of rotors in cardiac fibrillation. We hypothesized that combining SVD analysis with WGCA should reveal whether rotor activity is the dominant driving force of fibrillation even in cases of high complexity. Optical mapping experiments were conducted in neonatal rat cardiomyocyte monolayers (diameter, 35 mm), which were genetically modified to overexpress the delayed rectifier K+ channel IKr only in one half of the monolayer. Such monolayers have been shown previously to sustain fast rotors confined to the IKr overexpressing half and driving fibrillatory-like activity in the other half. SVD analysis of the optical mapping movies revealed a hierarchical pattern in which the primary modes corresponded to rotor activity in the IKr overexpressing region and the secondary modes corresponded to fibrillatory activity elsewhere. We then applied WGCA to evaluate the directionality of influence between modes in the entire monolayer using clear and noisy movies of activity. We demonstrated that the rotor modes influence the secondary fibrillatory modes, but influence was detected also in the opposite direction. To more specifically delineate the role of the rotor in fibrillation, we decomposed separately the respective SVD modes of the rotor and fibrillatory domains. In this case, WGCA yielded more information from the rotor to the fibrillatory domains than in the opposite direction. In conclusion, SVD analysis reveals that rotors can be the dominant modes of an experimental model of fibrillation. Wiener-Granger causality on modes of the rotor domains confirms their preferential driving influence on fibrillatory modes.

Vibrational spectra for uric acid and its D- and 15N-substituted analogues. Assignments for its normal modes from ab initio 3-21G force field.

NASA Astrophysics Data System (ADS)

Majoube, M.; Vergoten, G.

1993-03-01

FTR, Raman, FTIR spectra are obtained for polycrystalline uric acid and seven of its D-and 15N-substituted analogues. Assignments are given from a normal coordinate analysis carried out using a 3-21G ab initio force field. These are discussed by considering observed and calculated frequencies and D- and 15N-isotopic shifts.

Normal mode Rossby waves observed in the upper stratosphere

NASA Technical Reports Server (NTRS)

Hirooka, T.; Hirota, I.

1985-01-01

In recent years, observational evidence has been obtained for westward traveling planetary waves in the middle atmosphere with the aid of global data from satellites. There is no doubt that the fair portion of the observed traveling waves can be understood as the manifestation of the normal mode Rossby waves which are theoretically derived from the tidal theory. Some observational aspects of the structure and behavior of the normal model Rossby waves in the upper stratosphere are reported. The data used are the global stratospheric geopotential thickness and height analyses which are derived mainly from the Stratospheric Sounding Units (SSUs) on board TIROS-N and NOAA satellites. A clear example of the influence of the normal mode Rossby wave on the mean flow is reported. The mechanism considered is interference between the normal mode Rossby wave and the quasi-stationary wave.

Modeling and simulation performance of photovoltaic system integration battery and supercapacitor paralellization of MPPT prototipe for solar vehicle

NASA Astrophysics Data System (ADS)

Ajiatmo, Dwi; Robandi, Imam

2017-03-01

This paper proposes a control scheme photovoltaic, battery and super capacitor connected in parallel for use in a solar vehicle. Based on the features of battery charging, the control scheme consists of three modes, namely, mode dynamic irradian, constant load mode and constant voltage charging mode. The shift of the three modes can be realized by controlling the duty cycle of the mosffet Boost converter system. Meanwhile, the high voltage which is more suitable for the application can be obtained. Compared with normal charging method with parallel connected current limiting detention and charging method with dynamic irradian mode, constant load mode and constant voltage charging mode, the control scheme is proposed to shorten the charging time and increase the use of power generated from the PV array. From the simulation results and analysis conducted to determine the performance of the system in state transient and steady-state by using simulation software Matlab / Simulink. Response simulation results demonstrate the suitability of the proposed concept.

Potential-based and non-potential-based cohesive zone formulations under mixed-mode separation and over-closure-Part II: Finite element applications

NASA Astrophysics Data System (ADS)

Máirtín, Éamonn Ó.; Parry, Guillaume; Beltz, Glenn E.; McGarry, J. Patrick

2014-02-01

This paper, the second of two parts, presents three novel finite element case studies to demonstrate the importance of normal-tangential coupling in cohesive zone models (CZMs) for the prediction of mixed-mode interface debonding. Specifically, four new CZMs proposed in Part I of this study are implemented, namely the potential-based MP model and the non-potential-based NP1, NP2 and SMC models. For comparison, simulations are also performed for the well established potential-based Xu-Needleman (XN) model and the non-potential-based model of van den Bosch, Schreurs and Geers (BSG model). Case study 1: Debonding and rebonding of a biological cell from a cyclically deforming silicone substrate is simulated when the mode II work of separation is higher than the mode I work of separation at the cell-substrate interface. An active formulation for the contractility and remodelling of the cell cytoskeleton is implemented. It is demonstrated that when the XN potential function is used at the cell-substrate interface repulsive normal tractions are computed, preventing rebonding of significant regions of the cell to the substrate. In contrast, the proposed MP potential function at the cell-substrate interface results in negligible repulsive normal tractions, allowing for the prediction of experimentally observed patterns of cell cytoskeletal remodelling. Case study 2: Buckling of a coating from the compressive surface of a stent is simulated. It is demonstrated that during expansion of the stent the coating is initially compressed into the stent surface, while simultaneously undergoing tangential (shear) tractions at the coating-stent interface. It is demonstrated that when either the proposed NP1 or NP2 model is implemented at the stent-coating interface mixed-mode over-closure is correctly penalised. Further expansion of the stent results in the prediction of significant buckling of the coating from the stent surface, as observed experimentally. In contrast, the BSG model does not correctly penalise mixed-mode over-closure at the stent-coating interface, significantly altering the stress state in the coating and preventing the prediction of buckling. Case study 3: Application of a displacement to the base of a bi-layered composite arch results in a symmetric sinusoidal distribution of normal and tangential traction at the arch interface. The traction defined mode mixity at the interface ranges from pure mode II at the base of the arch to pure mode I at the top of the arch. It is demonstrated that predicted debonding patterns are highly sensitive to normal-tangential coupling terms in a CZM. The NP2, XN, and BSG models exhibit a strong bias towards mode I separation at the top of the arch, while the NP1 model exhibits a bias towards mode II debonding at the base of the arch. Only the SMC model provides mode-independent behaviour in the early stages of debonding. This case study provides a practical example of the importance of the behaviour of CZMs under conditions of traction controlled mode mixity, following from the theoretical analysis presented in Part I of this study.

Eigenvalue equation and core-mode cutoff of weakly guiding tapered fiber as three layer optical waveguide and used as biochemical sensor.

PubMed

Linslal, C L; Mohan, P M S; Halder, A; Gangopadhyay, T K

2012-06-01

The core-mode cutoff plays a major role in evanescent field absorption based sensors. A method has been proposed to calculate the core-mode cutoff by solving the eigenvalue equations of a weakly guiding three layer optical waveguide graphically. The variation of normalized waveguide parameter (V) is also calculated with different wavelengths at core-mode cutoff. At the first step, theoretical analysis of tapered fiber parameters has been performed for core-mode cutoff. The taper angle of an adiabatic tapered fiber is also analyzed using the length-scale criterion. Secondly, single-mode tapered fiber has been developed to make a precision sensor element suitable for chemical detection. Finally, the sensor element has been used to detect absorption peak of ethylenediamine. Results are presented in which an absorption peak at 1540 nm is observed.

Domain motions of Argonaute, the catalytic engine of RNA interference

PubMed Central

Ming, Dengming; Wall, Michael E; Sanbonmatsu, Kevin Y

2007-01-01

Background The Argonaute protein is the core component of the RNA-induced silencing complex, playing the central role of cleaving the mRNA target. Visual inspection of static crystal structures already has enabled researchers to suggest conformational changes of Argonaute that might occur during RNA interference. We have taken the next step by performing an all-atom normal mode analysis of the Pyrococcus furiosus and Aquifex aeolicus Argonaute crystal structures, allowing us to quantitatively assess the feasibility of these conformational changes. To perform the analysis, we begin with the energy-minimized X-ray structures. Normal modes are then calculated using an all-atom molecular mechanics force field. Results The analysis reveals low-frequency vibrations that facilitate the accommodation of RNA duplexes – an essential step in target recognition. The Pyrococcus furiosus and Aquifex aeolicus Argonaute proteins both exhibit low-frequency torsion and hinge motions; however, differences in the overall architecture of the proteins cause the detailed dynamics to be significantly different. Conclusion Overall, low-frequency vibrations of Argonaute are consistent with mechanisms within the current reaction cycle model for RNA interference. PMID:18053142

Domain motions of Argonaute, the catalytic engine of RNA interference.

PubMed

Ming, Dengming; Wall, Michael E; Sanbonmatsu, Kevin Y

2007-11-30

The Argonaute protein is the core component of the RNA-induced silencing complex, playing the central role of cleaving the mRNA target. Visual inspection of static crystal structures already has enabled researchers to suggest conformational changes of Argonaute that might occur during RNA interference. We have taken the next step by performing an all-atom normal mode analysis of the Pyrococcus furiosus and Aquifex aeolicus Argonaute crystal structures, allowing us to quantitatively assess the feasibility of these conformational changes. To perform the analysis, we begin with the energy-minimized X-ray structures. Normal modes are then calculated using an all-atom molecular mechanics force field. The analysis reveals low-frequency vibrations that facilitate the accommodation of RNA duplexes - an essential step in target recognition. The Pyrococcus furiosus and Aquifex aeolicus Argonaute proteins both exhibit low-frequency torsion and hinge motions; however, differences in the overall architecture of the proteins cause the detailed dynamics to be significantly different. Overall, low-frequency vibrations of Argonaute are consistent with mechanisms within the current reaction cycle model for RNA interference.

Systematic approach to study of thinly and thickly sectioned melanoma tissues with scanning acoustic microscopy

NASA Astrophysics Data System (ADS)

Miyasaka, C.; Tittmann, B. R.; Tutwiler, R.; Tian, Y.; Maeva, E.; Shum, D.

2010-03-01

The present study is to investigate the feasibility of applying in-vivo acoustic microscopy to the analysis of cancerous tissue. The study was implemented with mechanical scanning reflection acoustic microscope (SAM) by the following procedures. First, we ultrasonically visualized thick sections of normal and tumor tissues to determine the lowest transducer frequency required for cellular imaging. We used skin for normal tissue and the tumor was a malignant melanoma. Thin sections of the tissue were also studied with the optical and high-frequency-ultrasonic imaging for pathological evaluation. Secondly, we ultrasonically visualized subsurface cellular details of thin tissue specimens with different modes (i.e., pulse and tone-burst wave modes) to obtain the highest quality ultrasonic images. The objective is to select the best mode for the future design of a future SAM for in-vivo examination. Thirdly, we developed a mathematical modeling technique based on an angular spectrum approach for improving image processing and comparing numerical to experimental results.

Acoustic-gravity waves in atmospheric and oceanic waveguides.

PubMed

Godin, Oleg A

2012-08-01

A theory of guided propagation of sound in layered, moving fluids is extended to include acoustic-gravity waves (AGWs) in waveguides with piecewise continuous parameters. The orthogonality of AGW normal modes is established in moving and motionless media. A perturbation theory is developed to quantify the relative significance of the gravity and fluid compressibility as well as sensitivity of the normal modes to variations in sound speed, flow velocity, and density profiles and in boundary conditions. Phase and group speeds of the normal modes are found to have certain universal properties which are valid for waveguides with arbitrary stratification. The Lamb wave is shown to be the only AGW normal mode that can propagate without dispersion in a layered medium.

Turbulent transport measurements with a laser Doppler velocimeter.

NASA Technical Reports Server (NTRS)

Edwards, R. V.; Angus, J. C.; Dunning, J. W., Jr.

1972-01-01

The power spectrum of phototube current from a laser Doppler velocimeter operating in the heterodyne mode has been computed. The spectral width and shape predicted by the theory are in agreement with experiment. For normal operating parameters the time-average spectrum contains information only for times shorter than the Lagrangian-integral time scale of the turbulence. To examine the long-time behavior, one must use either extremely small scattering angles, much-longer-wavelength radiation, or a different mode of signal analysis, e.g., FM detection.

Jeans instability of rotating magnetized dusty plasma

NASA Astrophysics Data System (ADS)

Sharma, S.; Sutar, D. L.; Kumar, V.; Pensia, R. K.

2018-05-01

It has been shown that rotation has to play a predominant important role in the formation of many astrophysical objects and the stability of molecular clouds. In this paper the theoretical investigation of the presence of rotation in the magnetized dusty plasma. The general dispersion relation is obtained normal mode analysis technique, and we found the Alfven mode is modified due to the presence of rotation and magnetic field. The graphical presentation shows that rotation and Alfven wave velocity have a stabilizing in the system.

Non-modal analysis of the diocotron instability: Cylindrical geometry

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

Mikhailenko, V. V.; Lee, Hae June; Mikhailenko, V. S.

2013-04-15

The temporal evolution of the linear diocotron instability of the cylindrical annular plasma column is investigated by employing the extension of the shearing modes methodology to the cylindrical geometry. It was obtained that the spatial time-dependent distortion of the electron density initial perturbations by shear flows leads to the non-modal evolution of the potential, which was referred to as the manifestation of the continuous spectrum. The evolution process leads toward the convergence to the phase-locking configuration of the mutually growing normal modes.

Normal Mode Analysis in Zeolites: Toward an Efficient Calculation of Adsorption Entropies.

PubMed

De Moor, Bart A; Ghysels, An; Reyniers, Marie-Françoise; Van Speybroeck, Veronique; Waroquier, Michel; Marin, Guy B

2011-04-12

An efficient procedure for normal-mode analysis of extended systems, such as zeolites, is developed and illustrated for the physisorption and chemisorption of n-octane and isobutene in H-ZSM-22 and H-FAU using periodic DFT calculations employing the Vienna Ab Initio Simulation Package. Physisorption and chemisorption entropies resulting from partial Hessian vibrational analysis (PHVA) differ at most 10 J mol(-1) K(-1) from those resulting from full Hessian vibrational analysis, even for PHVA schemes in which only a very limited number of atoms are considered free. To acquire a well-conditioned Hessian, much tighter optimization criteria than commonly used for electronic energy calculations in zeolites are required, i.e., at least an energy cutoff of 400 eV, maximum force of 0.02 eV/Å, and self-consistent field loop convergence criteria of 10(-8) eV. For loosely bonded complexes the mobile adsorbate method is applied, in which frequency contributions originating from translational or rotational motions of the adsorbate are removed from the total partition function and replaced by free translational and/or rotational contributions. The frequencies corresponding with these translational and rotational modes can be selected unambiguously based on a mobile block Hessian-PHVA calculation, allowing the prediction of physisorption entropies within an accuracy of 10-15 J mol(-1) K(-1) as compared to experimental values. The approach presented in this study is useful for studies on other extended catalytic systems.

Calculation and Comparative Analysis of the IR Spectra of Homobrassinolide and (22S,23S)-Homobrassinolide

NASA Astrophysics Data System (ADS)

Andrianov, V. M.; Korolevich, M. V.

2015-09-01

Normal vibrational frequencies and absolute IR band intensities of the biologically active steroid phytohormones homobrassinolide and (22S,23S)-homobrassinolide were calculated in the framework of an original approach that combined classical analysis of normal modes using molecular mechanics with quantum-chemical estimation of the absolute intensities. IR absorption bands were interpreted based on a comparison of the experimental and theoretical absorption spectra. The impact of structural differences in the side chains of these molecules on the formation of their IR spectra in the region 1500-950 cm -1 was estimated.

Study on steric transition in asymmetrical flow field-flow fractionation and application to characterization of high-energy material.

PubMed

Dou, Haiyang; Lee, Yong-Ju; Jung, Euo Chang; Lee, Byung-Chul; Lee, Seungho

2013-08-23

In field-flow fractionation (FFF), there is the 'steric transition' phenomenon where the sample elution mode changes from the normal to steric/hyperlayer mode. Accurate analysis by FFF requires understanding of the steric transition phenomenon, particularly when the sample has a broad size distribution, for which the effect by combination of different modes may become complicated to interpret. In this study, the steric transition phenomenon in asymmetrical flow FFF (AF4) was studied using polystyrene (PS) latex beads. The retention ratio (R) gradually decreases as the particle size increases (normal mode) and reaches a minimum (Ri) at diameter around 0.5μm, after which R increases with increasing diameter (steric/hyperlayer mode). It was found that the size-based selectivity (Sd) tends to increase as the channel thickness (w) increases. The retention behavior of cyclo-1,3,5-trimethylene-2,4,6-trinitramine (commonly called 'research department explosive' (RDX)) particles in AF4 was investigated by varying experimental parameters including w and flow rates. AF4 showed a good reproducibility in size determination of RDX particles with the relative standard deviation of 4.1%. The reliability of separation obtained by AF4 was evaluated by transmission electron microscopy (TEM). Copyright © 2013 Elsevier B.V. All rights reserved.

FIBER AND INTEGRATED OPTICS: Noncollinear geometry for highly efficient excitation of a corrugated waveguide

NASA Astrophysics Data System (ADS)

Klimov, M. S.; Sychugov, V. A.; Tishchenko, A. V.

1992-02-01

An analysis is made of the process of light emission from a corrugated waveguide into air and into a substrate in a noncollinear geometry, i.e., when the direction along which the waveguide mode propagates does not coincide with the plane in which the emitted wave lies. Calculations show that when a TE mode is excited in a corrugated waveguide by a light beam with the TM polarization incident from air on the waveguide at a grazing angle, one can achieve a high waveguide excitation efficiency (~ 60%) if the waveguide mode propagates along the normal to the plane of incidence.

Cavity enhanced interference of orthogonal modes in a birefringent medium

NASA Astrophysics Data System (ADS)

Kolluru, Kiran; Saha, Sudipta; Gupta, S. Dutta

2018-03-01

Interference of orthogonal modes in a birefringent crystal mediated by a rotator is known to lead to interesting physical effects (Solli et al., 2003). In this paper we show that additional feedback offered by a Fabry-Perot cavity (containing the birefringent crystal and the rotator) can lead to a novel strong interaction regime. Usual signatures of the strong interaction regime like the normal mode splitting and avoided crossings, sensitive to the rotator orientation, are reported. A high finesse cavity is shown to offer an optical setup for measuring small angles. The results are based on direct calculations of the cavity transmissions along with an analysis of its dispersion relation.

Research on Snake-Like Robot with Controllable Scales

NASA Astrophysics Data System (ADS)

Chen, Kailin; Zhao, Yuting; Chen, Shuping

The purpose of this paper is to propose a new structure for a snake-like robot. This type of snake-like robot is different from the normal snake-like robot because it has lots of controllable scales which have a large role in helping moving. Besides, a new form of robot gait named as linear motion mode is developed based on theoretical analysis for the new mechanical structure. Through simulation and analysis in simmechanics of matlab, we proved the validity of theories about the motion mode of snake-like robot. The proposed machine construction and control method for the designed motion is verified experimentally by the independent developed snake robot.

Improved dynamic analysis method using load-dependent Ritz vectors

NASA Technical Reports Server (NTRS)

Escobedo-Torres, J.; Ricles, J. M.

1993-01-01

The dynamic analysis of large space structures is important in order to predict their behavior under operating conditions. Computer models of large space structures are characterized by having a large number of degrees of freedom, and the computational effort required to carry out the analysis is very large. Conventional methods of solution utilize a subset of the eigenvectors of the system, but for systems with many degrees of freedom, the solution of the eigenproblem is in many cases the most costly phase of the analysis. For this reason, alternate solution methods need to be considered. It is important that the method chosen for the analysis be efficient and that accurate results be obtainable. It is important that the method chosen for the analysis be efficient and that accurate results be obtainable. The load dependent Ritz vector method is presented as an alternative to the classical normal mode methods for obtaining dynamic responses of large space structures. A simplified model of a space station is used to compare results. Results show that the load dependent Ritz vector method predicts the dynamic response better than the classical normal mode method. Even though this alternate method is very promising, further studies are necessary to fully understand its attributes and limitations.

Evaluation of coupling terms between intra- and intermolecular vibrations in coarse-grained normal-mode analysis: does a stronger acid make a stiffer hydrogen bond?

PubMed

Houjou, Hirohiko

2011-10-21

Using theory of harmonic normal-mode vibration analysis, we developed a procedure for evaluating the anisotropic stiffness of intermolecular forces. Our scheme for coarse-graining of molecular motions is modified so as to account for intramolecular vibrations in addition to relative translational/rotational displacement. We applied this new analytical scheme to four carboxylic acid dimers, for which coupling between intra- and intermolecular vibrations is crucial for determining the apparent stiffness of the intermolecular double hydrogen bond. The apparent stiffness constant was analyzed on the basis of a conjunct spring model, which defines contributions from true intermolecular stiffness and molecular internal stiffness. Consequently, the true intermolecular stiffness was in the range of 43-48 N m(-1) for all carboxylic acids studied, regardless of the molecules' acidity. We concluded that the difference in the apparent stiffness can be attributed to differences in the internal stiffness of the respective molecules. © 2011 American Institute of Physics

Evaluation of coupling terms between intra- and intermolecular vibrations in coarse-grained normal-mode analysis: Does a stronger acid make a stiffer hydrogen bond?

NASA Astrophysics Data System (ADS)

Houjou, Hirohiko

2011-10-01

Using theory of harmonic normal-mode vibration analysis, we developed a procedure for evaluating the anisotropic stiffness of intermolecular forces. Our scheme for coarse-graining of molecular motions is modified so as to account for intramolecular vibrations in addition to relative translational/rotational displacement. We applied this new analytical scheme to four carboxylic acid dimers, for which coupling between intra- and intermolecular vibrations is crucial for determining the apparent stiffness of the intermolecular double hydrogen bond. The apparent stiffness constant was analyzed on the basis of a conjunct spring model, which defines contributions from true intermolecular stiffness and molecular internal stiffness. Consequently, the true intermolecular stiffness was in the range of 43-48 N m-1 for all carboxylic acids studied, regardless of the molecules' acidity. We concluded that the difference in the apparent stiffness can be attributed to differences in the internal stiffness of the respective molecules.

Discriminant analysis to predict the occurrence of ELMS in H-mode discharges

NASA Astrophysics Data System (ADS)

Kardaun, O. J. W. F.; Itoh, S.-I.; Itoh, K.; Kardaun, J. W. P. F.

1993-08-01

After an exposition of its theoretical background, discriminant analysis is applied to the H-mode confinement database to find the region in plasma parameter space in which H-mode with small ELM's (Edge Localized Modes) is likely to occur. The boundary of this region is determined by the condition that the probability of appearance of such a type of H-mode, as a function of the plasma parameters, should be larger than some threshold value and larger than the corresponding probability for other types of H-mode (i.e., H-mode without ELM's or with giant ELM's). In practice, the discrimination has been performed for the ASDEX, JET and JFT-2M tokamaks using four instantaneous plasma parameters (injected power Pinj, magnetic field Bt, plasma current Ip and line averaged electron density ne) and taking also memory effects of the plasma and the distance between the plasma and the wall into account, while using variables that are normalized with respect to machine size. Generally speaking, it is found that there is a substantial overlap between the region of H-mode with small ELM's and the region of the two other types of H-mode. However, the ELM-free and the giant ELM H-modes relatively rarely appear in the region, that, according to the analysis, is allocated to small ELM's. A reliable production of H-mode with only small ELM's seems well possible by choosing this regime in parameter space. In the present study, it was not attempted to arrive at a unified discrimination across the machines. So, projection from one machine to another remains difficult, and a reliable determination of the region where small ELM's occur still requires a training sample from the device under consideration.

Ku-band radar threshold analysis

NASA Technical Reports Server (NTRS)

Weber, C. L.; Polydoros, A.

1979-01-01

The statistics of the CFAR threshold for the Ku-band radar was determined. Exact analytical results were developed for both the mean and standard deviations in the designated search mode. The mean value is compared to the results of a previously reported simulation. The analytical results are more optimistic than the simulation results, for which no explanation is offered. The normalized standard deviation is shown to be very sensitive to signal-to-noise ratio and very insensitive to the noise correlation present in the range gates of the designated search mode. The substantial variation in the CFAR threshold is dominant at large values of SNR where the normalized standard deviation is greater than 0.3. Whether or not this significantly affects the resulting probability of detection is a matter which deserves additional attention.

Anomalous waveforms observed in laboratory-formed gas hydrate-bearing and ice-bearing sediments

USGS Publications Warehouse

Lee, M.W.; Waite, W.F.

2011-01-01

Acoustic transmission measurements of compressional, P, and shear, S, wave velocities rely on correctly identifying the P- and S-body wave arrivals in the measured waveform. In cylindrical samples for which the sample is much longer than the acoustic wavelength, these body waves can be obscured by high-amplitude waveform features arriving just after the relatively small-amplitude P-body wave. In this study, a normal mode approach is used to analyze this type of waveform, observed in sediment containing gas hydrate or ice. This analysis extends an existing normal-mode waveform propagation theory by including the effects of the confining medium surrounding the sample, and provides guidelines for estimating S-wave velocities from waveforms containing multiple large-amplitude arrivals. ?? 2011 Acoustical Society of America.

An Eigenvalue Analysis of finite-difference approximations for hyperbolic IBVPs

NASA Technical Reports Server (NTRS)

Warming, Robert F.; Beam, Richard M.

1989-01-01

The eigenvalue spectrum associated with a linear finite-difference approximation plays a crucial role in the stability analysis and in the actual computational performance of the discrete approximation. The eigenvalue spectrum associated with the Lax-Wendroff scheme applied to a model hyperbolic equation was investigated. For an initial-boundary-value problem (IBVP) on a finite domain, the eigenvalue or normal mode analysis is analytically intractable. A study of auxiliary problems (Dirichlet and quarter-plane) leads to asymptotic estimates of the eigenvalue spectrum and to an identification of individual modes as either benign or unstable. The asymptotic analysis establishes an intuitive as well as quantitative connection between the algebraic tests in the theory of Gustafsson, Kreiss, and Sundstrom and Lax-Richtmyer L(sub 2) stability on a finite domain.

Noncircular features in Saturn's rings III: The Cassini Division

NASA Astrophysics Data System (ADS)

French, Richard G.; Nicholson, Philip D.; McGhee-French, Colleen A.; Lonergan, Katherine; Sepersky, Talia; Hedman, Mathew M.; Marouf, Essam A.; Colwell, Joshua E.

2016-08-01

We have conducted a comprehensive survey of 22 sharp-edged ringlets and gaps in the Cassini Division of Saturn's rings, making use of nearly 200 high-SNR stellar and radio occultation chords obtained by the Cassini VIMS, UVIS, and RSS instruments between 2005 and 2013. We measure eccentricities from as small as ae = 80 m to nearly 30 km, free normal modes with amplitudes from ∼ 0.1 to 4.1 km, and detectable inclinations as small as asini = 0.2 km. Throughout the entire region, the Mimas 2.1 ILR (inner Lindblad resonance) produces systematic forced m = 2 distortions that quantitatively match the expected amplitudes, phases, and pattern speed. The narrow Russell, Jeffreys, Kuiper, Bessel, and Barnard gaps are simplest, and do not contain dense ringlets. Their outer edges are generally quite sharp and four of them are circular to within ∼0.25 km, whereas most of the inner gap edges have significant eccentricities. Three gaps are more complex, containing one or more isolated ringlets. First among these is the 361 km-wide Huygens gap, containing two ringlets. The wider Huygens ringlet has nearly identical eccentricities on the two edges, in addition to OLR-type (outer Lindblad resonance) normal modes on the inner edge and ILR-type modes on the outer edge. A secondary m = 1 (eccentric) mode is present on the outer edge of the ringlet, with a pattern speed similar to that of the B ring's outer edge. Variations in the ringlet's width are complex, but are statistically consistent with the expected magnitudes resulting from the random superposition of the multiple normal modes on the two edges. Also present in the Huygens gap is the very narrow so-called Strange ringlet, with a substantial eccentricity and inclination, as well as both ILR- and OLR-type normal modes. The 100 km-wide Herschel gap's inner edge is highly eccentric, with at least seven ILR-type normal modes. The outer gap edge is also eccentric, and hosts four OLR-type normal modes, and a secondary m = 1 mode with a pattern speed quite close to that of the B ring's outer edge. The Herschel ringlet itself is eccentric and inclined, but neither the pericenters nor the nodes are well-aligned. The third of the complex gaps is the 241 km-wide Laplace gap, containing the Laplace ringlet. Both gap edges are eccentric, with very similar pericenter longitudes and apsidal precession rates, in spite of their large radial separation. The Laplace ringlet has eccentric edges and an abundance of normal modes. Like the Herschel ringlet, the Laplace ringlet does not precess rigidly and does not conform to the usual dynamical picture of an eccentric ringlet. Normal modes are abundant in the Cassini Division. Consistently, we find free ILR-type normal modes (m > 0) at the outer edges of ringlets and the inner edges of gaps, and free OLR-type normal modes (m ≤ 0) at inner ringlet edges and outer edges of gaps, as expected from the resonant cavity model of normal modes. We estimate the surface density of ring features from the resonance locations of the normal modes. The Cassini Division exhibits apsidal precession rates that are anomalously large, compared to the predicted values based on Saturn's zonal gravity field. The overall radial trend matches the secular contribution expected from the nearby B ring, assuming a surface mass density of Σ = 100 gm cm-2. However, the outer edges of the Huygens and Laplace gaps, and the outer edge of the Laplace ringlet, have conspicuously large residuals, exceeding their predicted precession rates by more than 0 .03∘d-1 . These patterns are probably the result of forcing by nearby ring material, but at present we cannot account for them in detail.

Preliminary Results of Low Energy Sputter Yields of Boron Nitride due to Xenon Ion Bombardment (Preprint)

DTIC Science & Technology

2008-07-07

from normal. Comparison with past measurement results are made where possible. I. Nomenclature As = sensor area of QCM E = beam ion...use a combination of weight-loss and QCM deposition sensor and builds upon our previous work 5-7, 9- 10 . In Section III we summarize our experimental...containing the surface normal and the incident ion directions). E. QCM Sensor and Signal Analysis In deposition mode, the QCM allows

Calculation of density functional theory (DFT) vibrational parameters of nucleotides for use in theoretical optical calculations: Herein applied to circular dichroism (CD) and absorption of polynucleotides

NASA Astrophysics Data System (ADS)

Ferber, Steven Dwight

2005-11-01

The Vibrational Circular Dichroism (VCD) of Nucleic Acids is a sensitive function of their conformation. DeVoe's classically derived polarizability theory allows the calculation of polymer absorption and circular dichroism spectra in any frequency range. Following the approach of Tinoco and Cech as modified by Moore and Self, calculations were done in the infrared (IR) region with theoretically derived monomer input parameters. Presented herein are calculated absorption and CD spectra for nucleic acid oligomers and polymers. These calculations improve upon earlier attempts, which utilized frequencies, intensities and normal modes from empirical analysis of the nitrogenous base of the monomers. These more complete input polarizability parameters include all contributions to specific vibrational normal modes for the entire nucleotide structure. They are derived from density functional theory (DFT) vibrational analysis on quasi-nucleotide monomers using the GAUSSIAN '98/'03 program. The normal modes are "integrated" for the first time into single virtual (DeVoe) oscillators by incorporating "fixed partial charges" in the manner of Schellman. The results include the complete set of monomer normal modes. All of these modes may be analyzed, in a manner similar to those demonstrated here (for the 1500-1800 cm-1 region). A model is utilized for the polymer/oligomer monomers which maintains the actual electrostatic charge on the adjacent protonated phosphoryl groups (hydrogen phosphate, a mono-anion). This deters the optimization from "collapsing" into a hydrogen-bonded "ball" and thereby maintains the extended (polymer-like) conformation. As well, the precise C2 "endo" conformation of the sugar ring is maintained in the DNA monomers. The analogous C3 "endo" conformation is also maintained for the RNA monomers, which are constrained by massive "anchors" at the phosphates. The complete IR absorbance spectra (0-4,000 cm-1) are calculated directly in Gaussian. Calculated VCD and Absorbance Spectra for the eight standard Ribonucleic and Deoxy-ribonucleic acid homo-polymers in the nitrogenous base absorbing region 1550-1750 cm-1 are presented. These spectra match measured spectra at least as well as spectra calculated from empirical parameters. These results demonstrate that the purely theoretical calculation, an example given herein, should serve to provide more transferable, universal parameters for the polarizability treatment of the optical properties of oligomers and polymers.

Modeling of human operator dynamics in simple manual control utilizing time series analysis. [tracking (position)

NASA Technical Reports Server (NTRS)

Agarwal, G. C.; Osafo-Charles, F.; Oneill, W. D.; Gottlieb, G. L.

1982-01-01

Time series analysis is applied to model human operator dynamics in pursuit and compensatory tracking modes. The normalized residual criterion is used as a one-step analytical tool to encompass the processes of identification, estimation, and diagnostic checking. A parameter constraining technique is introduced to develop more reliable models of human operator dynamics. The human operator is adequately modeled by a second order dynamic system both in pursuit and compensatory tracking modes. In comparing the data sampling rates, 100 msec between samples is adequate and is shown to provide better results than 200 msec sampling. The residual power spectrum and eigenvalue analysis show that the human operator is not a generator of periodic characteristics.

Polyad breaking phenomenon associated with a local-to-normal mode transition and suitability to estimate force constants

NASA Astrophysics Data System (ADS)

Bermúdez-Montaña, M.; Lemus, R.; Castaños, O.

2017-12-01

In a system of two interacting harmonic oscillators a local-to-normal mode transition is manifested as a polyad breaking phenomenon. This phenomenon is associated with the suitability to estimate zeroth-order force constants in the framework of a local mode description. This transition is also exhibited in two interacting Morse oscillators. To study this case, an appropriate parameterisation going from a molecule with local mode behaviour (H2O) to a molecule presenting a normal mode behaviour (CO2) is introduced. Concepts from quantum mechanics like fidelity, entropy and probability density, as well from nonlinear classical mechanics like Poincaré sections are used to detect the transition region. It is found that fidelity and entropy are sensitive complementary properties to detect the local-to-normal transition. Poincaré sections allow the local-to-normal transition to be detected through the appearance of chaos as a consequence of the polyad breaking phenomenon. In addition, two kinds of avoided energy crossings are identified in accordance with the different regions of the spectrum.

Conformational variability of the stationary phase survival protein E from Xylella fastidiosa revealed by X-ray crystallography, small-angle X-ray scattering studies, and normal mode analysis.

PubMed

Machado, Agnes Thiane Pereira; Fonseca, Emanuella Maria Barreto; Reis, Marcelo Augusto Dos; Saraiva, Antonio Marcos; Santos, Clelton Aparecido Dos; de Toledo, Marcelo Augusto Szymanski; Polikarpov, Igor; de Souza, Anete Pereira; Aparicio, Ricardo; Iulek, Jorge

2017-10-01

Xylella fastidiosa is a xylem-limited bacterium that infects a wide variety of plants. Stationary phase survival protein E is classified as a nucleotidase, which is expressed when bacterial cells are in the stationary growth phase and subjected to environmental stresses. Here, we report four refined X-ray structures of this protein from X. fastidiosa in four different crystal forms in the presence and/or absence of the substrate 3'-AMP. In all chains, the conserved loop verified in family members assumes a closed conformation in either condition. Therefore, the enzymatic mechanism for the target protein might be different of its homologs. Two crystal forms exhibit two monomers whereas the other two show four monomers in the asymmetric unit. While the biological unit has been characterized as a tetramer, differences of their sizes and symmetry are remarkable. Four conformers identified by Small-Angle X-ray Scattering (SAXS) in a ligand-free solution are related to the low frequency normal modes of the crystallographic structures associated with rigid body-like protomer arrangements responsible for the longitudinal and symmetric adjustments between tetramers. When the substrate is present in solution, only two conformers are selected. The most prominent conformer for each case is associated to a normal mode able to elongate the protein by moving apart two dimers. To our knowledge, this work was the first investigation based on the normal modes that analyzed the quaternary structure variability for an enzyme of the SurE family followed by crystallography and SAXS validation. The combined results raise new directions to study allosteric features of XfSurE protein. © 2017 Wiley Periodicals, Inc.

PyVCI: A flexible open-source code for calculating accurate molecular infrared spectra

NASA Astrophysics Data System (ADS)

Sibaev, Marat; Crittenden, Deborah L.

2016-06-01

The PyVCI program package is a general purpose open-source code for simulating accurate molecular spectra, based upon force field expansions of the potential energy surface in normal mode coordinates. It includes harmonic normal coordinate analysis and vibrational configuration interaction (VCI) algorithms, implemented primarily in Python for accessibility but with time-consuming routines written in C. Coriolis coupling terms may be optionally included in the vibrational Hamiltonian. Non-negligible VCI matrix elements are stored in sparse matrix format to alleviate the diagonalization problem. CPU and memory requirements may be further controlled by algorithmic choices and/or numerical screening procedures, and recommended values are established by benchmarking using a test set of 44 molecules for which accurate analytical potential energy surfaces are available. Force fields in normal mode coordinates are obtained from the PyPES library of high quality analytical potential energy surfaces (to 6th order) or by numerical differentiation of analytic second derivatives generated using the GAMESS quantum chemical program package (to 4th order).

Quasi-Normal Modes of Stars and Black Holes.

PubMed

Kokkotas, Kostas D; Schmidt, Bernd G

1999-01-01

Perturbations of stars and black holes have been one of the main topics of relativistic astrophysics for the last few decades. They are of particular importance today, because of their relevance to gravitational wave astronomy. In this review we present the theory of quasi-normal modes of compact objects from both the mathematical and astrophysical points of view. The discussion includes perturbations of black holes (Schwarzschild, Reissner-Nordström, Kerr and Kerr-Newman) and relativistic stars (non-rotating and slowly-rotating). The properties of the various families of quasi-normal modes are described, and numerical techniques for calculating quasi-normal modes reviewed. The successes, as well as the limits, of perturbation theory are presented, and its role in the emerging era of numerical relativity and supercomputers is discussed.

Atmospheric resonances of the Rayleigh and tsunami normal modes and its sensitivity to local time and geographical location.

NASA Astrophysics Data System (ADS)

Rakoto, V.; Astafyeva, E.; Lognonne, P. H.

2017-12-01

It is known that natural hazard events, such as earthquakes, tsunamis, volcano eruptions, etc. can generate atmospheric/ionospheric perturbations. During earthquakes, vertical displacements of the ground or of the ocean floor generate acoustic-gravity waves that further propagate upward in the upper atmosphere and ionosphere. In turn, tsunamis propagating in the open sea, generate gravity waves which propagate obliquely and reach the ionosphere in 45-60 min. The properties of the atmospheric "channel" in the vertical and oblique propagation depend on a variety of factors such as solar and geomagnetic conditions, latitude, local time, season, and their influence on propagation and properties of co-seismic and co-tsunamic perturbations is not well understood yet. In this work, we use present a detailed study of the coupling efficiency between solid earth, ocean and atmosphere. For this purpose, we use the normal mode technique extended to the whole solid Earth-ocean-atmosphere system. In our study, we focus on the Rayleigh modes (solid modes) and tsunami modes (oceanic modes). As the normal modes amplitude are also depending on the spatial and temporal variation of the structure of the atmosphere, we also performed a sensitivity study location of the normal modes amplitude with local time and geographical position.

COBE DMR-normalized open inflation cold dark matter cosmogony

NASA Technical Reports Server (NTRS)

Gorski, Krzysztof M.; Ratra, Bharat; Sugiyama, Naoshi; Banday, Anthony J.

1995-01-01

A cut-sky orthogonal mode analysis of the 2 year COBE DMR 53 and 90 GHz sky maps (in Galactic coordinates) is used to determine the normalization of an open inflation model based on the cold dark matter (CDM) scenario. The normalized model is compared to measures of large-scale structure in the universe. Although the DMR data alone does not provide sufficient discriminative power to prefer a particular value of the mass density parameter, the open model appears to be reasonably consistent with observations when Omega(sub 0) is approximately 0.3-0.4 and merits further study.

Topography-coupled resonance between Mars normal-modes and the tidal force of the Phobos

NASA Astrophysics Data System (ADS)

Tian, Y.; Zheng, Y.

2016-12-01

Phobos is the largest moon of Mars. The gravity attraction of Phobos to Mars is a periodic force, which may excite seismic waves inside Mars. Since Phobos is below the synchronous orbit, its orbit is continuously decreasing due to the tidal effect. This will result in a monotonic increase in its orbital frequency, which may eventually intrude into the seismic normal-mode frequency range to cause resonance. The objective of this research is to investigate whether such a resonance phenomenon can occur and what the consequence is. As we know, resonance happens when the periodic tidal force has a similar frequency as that of martian normal modes. It can be shown that such a resonance will not occur if Mars is perfectly spherical because the tidal force can only excite modes of the same angular order. For the same angular order, the tidal force frequencies are always smaller than those of the normal modes. However, when we consider the effect of topography of Mars, the resonance can occur because of coupling of normal modes. We use numerical method to calculate when the resonance will occur. We firstly solve for the normal modes of Mars by idealizing it as a solid elastic sphere. At the second step, we calculate the excitation effect of gravitational force from Phobos on each individual normal mode. For example, the gravity tidal force F at L=5, m=5 F55 can excite a normal mode 0S5 which can be coupled to 0T2. The third step is to calculate the frequency that the resonance will happen. For example, when the rotation frequency of Phobos increase to 0.8 mRad/s, the tidal force at L=5, m=5 can reach 4mRad/s which is the eigen-frequency of 0T2. Since we have calculated the coupling factors between each individual mode, the amplitude coefficients can be solved by a linear equation. We can observe a 100 times of amplitude increase of mode 0T2, which convince us the resonance will happen. The resonance may cause large amplitude of ground vibration of Mars. From our calculation, when the resonance happen, the energy dissipation rate will be greatly increased, which will make Phobos falling much faster. Eventually, Phobos will hit Mars in a very short time. Our research may give us a new prospective on early formation of planets.

A modal aeroelastic analysis scheme for turbomachinery blading. M.S. Thesis - Case Western Reserve Univ. Final Report

NASA Technical Reports Server (NTRS)

Smith, Todd E.

1991-01-01

An aeroelastic analysis is developed which has general application to all types of axial-flow turbomachinery blades. The approach is based on linear modal analysis, where the blade's dynamic response is represented as a linear combination of contributions from each of its in-vacuum free vibrational modes. A compressible linearized unsteady potential theory is used to model the flow over the oscillating blades. The two-dimensional unsteady flow is evaluated along several stacked axisymmetric strips along the span of the airfoil. The unsteady pressures at the blade surface are integrated to result in the generalized force acting on the blade due to simple harmonic motions. The unsteady aerodynamic forces are coupled to the blade normal modes in the frequency domain using modal analysis. An iterative eigenvalue problem is solved to determine the stability of the blade when the unsteady aerodynamic forces are included in the analysis. The approach is demonstrated by applying it to a high-energy subsonic turbine blade from a rocket engine turbopump power turbine. The results indicate that this turbine could undergo flutter in an edgewise mode of vibration.

String-Coupled Pendulum Oscillators: Theory and Experiment.

ERIC Educational Resources Information Center

Moloney, Michael J.

1978-01-01

A coupled-oscillator system is given which is readily set up, using only household materials. The normal-mode analysis of this system is worked out, and an experiment or demonstration is recommended in which one verifies the theory by measuring two times and four lengths. (Author/GA)

Carotid artery intima-media thickness measurement in children with normal and increased body mass index: a comparison of three techniques.

PubMed

El Jalbout, Ramy; Cloutier, Guy; Cardinal, Marie-Hélène Roy; Henderson, Mélanie; Lapierre, Chantale; Soulez, Gilles; Dubois, Josée

2018-05-09

Common carotid artery intima-media thickness is a marker of subclinical atherosclerosis. In children, increased intima-media thickness is associated with obesity and the risk of cardiovascular events in adulthood. To compare intima-media thickness measurements using B-mode ultrasound, radiofrequency (RF) echo tracking, and RF speckle probability distribution in children with normal and increased body mass index (BMI). We prospectively measured intima-media thickness in 120 children randomly selected from two groups of a longitudinal cohort: normal BMI and increased BMI, defined by BMI ≥85th percentile for age and gender. We followed Mannheim recommendations. We used M'Ath-Std for automated B-mode imaging, M-line processing of RF signal amplitude for RF echo tracking, and RF signal segmentation and averaging using probability distributions defining image speckle. Statistical analysis included Wilcoxon and Mann-Whitney tests, and Pearson correlation coefficient and intra-class correlation coefficient (ICC). Children were 10-13 years old (mean: 11.7 years); 61% were boys. The mean age was 11.4 years (range: 10.0-13.1 years) for the normal BMI group and 12.0 years (range: 10.1-13.5 years) for the increased BMI group. The normal BMI group included 58% boys and the increased BMI group 63% boys. RF echo tracking method was successful in 79 children as opposed to 114 for the B-mode method and all 120 for the probability distribution method. Techniques were weakly correlated: ICC=0.34 (95% confidence interval [CI]: 0.27-0.39). Intima-media thickness was significantly higher in the increased BMI than normal BMI group using the RF techniques and borderline for the B-mode technique. Mean differences between weight groups were: B-mode, 0.02 mm (95% CI: 0.00 to 0.04), P=0.05; RF echo tracking, 0.03 mm (95% CI: 0.01 to 0.05), P=0.01; and RF speckle probability distribution, 0.03 mm (95% CI: 0.01 to 0.05), P=0.002. Though techniques are not interchangeable, all showed increased intima-media thickness in children with increased BMI. RF echo tracking method had the lowest success rate at calculating intima-media thickness. For patient follow-up and cohort comparisons, the same technique should be used throughout.

Design Spectrum Analysis in NASTRAN

NASA Technical Reports Server (NTRS)

Butler, T. G.

1984-01-01

The utility of Design Spectrum Analysis is to give a mode by mode characterization of the behavior of a design under a given loading. The theory of design spectrum is discussed after operations are explained. User instructions are taken up here in three parts: Transient Preface, Maximum Envelope Spectrum, and RMS Average Spectrum followed by a Summary Table. A single DMAP ALTER packet will provide for all parts of the design spectrum operations. The starting point for getting a modal break-down of the response to acceleration loading is the Modal Transient rigid format. After eigenvalue extraction, modal vectors need to be isolated in the full set of physical coordinates (P-sized as opposed to the D-sized vectors in RF 12). After integration for transient response the results are scanned over the solution time interval for the peak values and for the times that they occur. A module called SCAN was written to do this job, that organizes these maxima into a diagonal output matrix. The maximum amplifier in each mode is applied to the eigenvector of each mode which then reveals the maximum displacements, stresses, forces and boundary reactions that the structure will experience for a load history, mode by mode. The standard NASTRAN output processors have been modified for this task. It is required that modes be normalized to mass.

Investigation of the piezoelectric thimble tactile device operating modes.

PubMed

Bansevicius, Ramutis; Dragasius, Egidijus; Grigas, Vytautas; Jurenas, Vytautas; Mazeika, Darius; Zvironas, Arunas

2014-01-01

A multifunctional device to transfer graphical or text information for blind or visually impaired is presented. The prototype using tactile perception has been designed where information displayed on the screen of electronic device (mobile phone, PC) is transferred by oscillating needle, touching the fingertip. Having the aim to define optimal parameters of the fingertip excitation by needle, the computational analysis of different excitation modes has been carried out. A 3D solid computational finite element model of the skin segment, comprising four main fingertip skin layers (stratum corneum, epidermis, dermis and hypodermis) was built by using ANSYS Workbench FEA software. Harmonic analysis of its stress-strain state under excitation with different frequency (up to 10000 Hz) and harmonic force (0.01 N), acting outer stratum corneum layer in normal direction at one, two or three points has been performed. The influence of the mode of dynamic loading of skin was evaluated (in terms of the tactile signal level) on the basis of the normal and shear elastic strain in dermis, where mechanoreceptors are placed. It is shown that the tactile perception of information, delivered by three vibrating pins, may be influenced by configuration of excitation points (their number and phase of loading) and the frequency of excitation.

A Preliminary Analysis of Wind Retrieval, Based on GF-3 Wave Mode Data.

PubMed

Wang, Lei; Han, Bing; Yuan, Xinzhe; Lei, Bin; Ding, Chibiao; Yao, Yulin; Chen, Qi

2018-05-17

This paper presents an analysis of measurements of the normalized radar cross-(NRCS) in Wave Mode for Chinese C-band Gaofen-3(GF-3) synthetic aperture radar (SAR). Based on 2779 images from GF-3 quad-polarization SAR in Wave Mode and collocated wind vectors from ERA-Interim, this experiment verifies the feasibility of using ocean surface wind fields and VV-polarized NRCS to perform normalized calibration. The method uses well-validated empirical C-band geophysical model function (CMOD4) to estimate the calibration constant for each beam. In addition, the relationship between cross-pol NRCS and wind vectors is discussed. The cross-pol NRCS increases linearly with wind speed and it is obviously modulated by the wind direction when the wind speed is greater than 8 m/s. Furthermore, the properties of the polarization ratio, denoted PR, are also investigated. The PR is dependent on incidence angle and azimuth angle. Two empirical models of the PR are fitted, one as a function of incidence angle only, the other with additional dependence on azimuth angle. Assessments show that the σ VV 0 retrieved from new PR models as well as σ HH 0 is in good agreement with σ VV 0 extracted from SAR images directly.

A Preliminary Analysis of Wind Retrieval, Based on GF-3 Wave Mode Data

PubMed Central

Wang, Lei; Han, Bing; Yuan, Xinzhe; Lei, Bin; Ding, Chibiao; Yao, Yulin; Chen, Qi

2018-01-01

This paper presents an analysis of measurements of the normalized radar cross-(NRCS) in Wave Mode for Chinese C-band Gaofen-3(GF-3) synthetic aperture radar (SAR). Based on 2779 images from GF-3 quad-polarization SAR in Wave Mode and collocated wind vectors from ERA-Interim, this experiment verifies the feasibility of using ocean surface wind fields and VV-polarized NRCS to perform normalized calibration. The method uses well-validated empirical C-band geophysical model function (CMOD4) to estimate the calibration constant for each beam. In addition, the relationship between cross-pol NRCS and wind vectors is discussed. The cross-pol NRCS increases linearly with wind speed and it is obviously modulated by the wind direction when the wind speed is greater than 8 m/s. Furthermore, the properties of the polarization ratio, denoted PR, are also investigated. The PR is dependent on incidence angle and azimuth angle. Two empirical models of the PR are fitted, one as a function of incidence angle only, the other with additional dependence on azimuth angle. Assessments show that the σVV0 retrieved from new PR models as well as σHH0 is in good agreement with σVV0 extracted from SAR images directly. PMID:29772821

Vibrational population relaxation of carbon monoxide in the heme pocket of photolyzed carbonmonoxy myoglobin: Comparison of time-resolved mid-IR absorbance experiments and molecular dynamics simulations

PubMed Central

Sagnella, Diane E.; Straub, John E.; Jackson, Timothy A.; Lim, Manho; Anfinrud, Philip A.

1999-01-01

The vibrational energy relaxation of carbon monoxide in the heme pocket of sperm whale myoglobin was studied by using molecular dynamics simulation and normal mode analysis methods. Molecular dynamics trajectories of solvated myoglobin were run at 300 K for both the δ- and ɛ-tautomers of the distal His-64. Vibrational population relaxation times of 335 ± 115 ps for the δ-tautomer and 640 ± 185 ps for the ɛ-tautomer were estimated by using the Landau–Teller model. Normal mode analysis was used to identify those protein residues that act as the primary “doorway” modes in the vibrational relaxation of the oscillator. Although the CO relaxation rates in both the ɛ- and δ-tautomers are similar in magnitude, the simulations predict that the vibrational relaxation of the CO is faster in the δ-tautomer with the distal His playing an important role in the energy relaxation mechanism. Time-resolved mid-IR absorbance measurements were performed on photolyzed carbonmonoxy hemoglobin (Hb13CO). From these measurements, a T1 time of 600 ± 150 ps was determined. The simulation and experimental estimates are compared and discussed. PMID:10588704

Investigation of Acoustic Structure Quantification in the Diagnosis of Thyroiditis.

PubMed

Park, Jisang; Hong, Hyun Sook; Kim, Chul-Hee; Lee, Eun Hye; Jeong, Sun Hye; Lee, A Leum; Lee, Heon

2016-03-01

The objective of this study was to evaluate the ability of acoustic structure quantification (ASQ) to diagnose thyroiditis. The echogenicity of 439 thyroid lobes, as determined using ASQ, was quantified and analyzed retrospectively. Thyroiditis was categorized into five subgroups. The results were presented in a modified chi-square histogram as the mode, average, ratio, blue mode, and blue average. We determined the cutoff values of ASQ from ROC analysis to detect and differentiate thyroiditis from a normal thyroid gland. We obtained data on the sensitivity and specificity of the cutoff values to distinguish between euthyroid patients with thyroiditis and patients with a normal thyroid gland. The mean ASQ values for patients with thyroiditis were statistically significantly greater than those for patients with a normal thyroid gland (p < 0.001). The AUCs were as follows: 0.93 for the ratio, 0.91 for the average, 0.90 for the blue average, 0.87 for the mode, and 0.87 for the blue mode. For the diagnosis of thyroiditis, the cutoff values were greater than 0.27 for the ratio, greater than 116.7 for the mean, and greater than 130.7 for the blue average. The sensitivities and specificities were as follows: 84.0% and 96.6% for the ratio, 85.3% and 83.0%, for the average, and 79.1% and 93.2% for the blue average, respectively. The ASQ parameters were successful in distinguishing patients with thyroiditis from patients with a normal thyroid gland, with likelihood ratios of 24.7 for the ratio, 5.0 for the average, and 11.6 for the blue average. With the use of the aforementioned cutoff values, the sensitivities and specificities for distinguishing between patients with thyroiditis and euthyroid patients without thyroiditis were 77.05% and 94.92% for the ratio, 85.25% and 82.20% for the average, and 77.05% and 92.37% for the blue average, respectively. ASQ can provide objective and quantitative analysis of thyroid echogenicity. ASQ parameters were successful in distinguishing between patients with thyroiditis and individuals without thyroiditis, with likelihood ratios of 24.7 for the ratio, 5.0 for the average, and 11.6 for the blue average.

The Scientific Return of VLT Programmes

NASA Astrophysics Data System (ADS)

Sterzik, M.; Dumas, C.; Grothkopf, U.; Kaufer, A.; Leibundgut, B.; Marteau, S.; Meakins, S.; Patat, F.; Primas, F.; Rejkuba, M.; Romaniello, M.; Stoehr, F.; Tacconi-Garman, L.; Vera, I.

2015-12-01

An in-depth analysis of the publications from 8414 distinct scheduled VLT observing programmes between April 1999 and March 2015 (Periods 63 to 94) is presented. The productivity by mode (Visitor or Service Mode) and type (Normal and Large, Guaranteed Time, Target of Opportunity, Director's Discretionary Time) are examined through their publication records. We investigate how Service Mode rank classes impact the scientific return. Several results derive from this study: Large Programmes result in the highest productivity, whereas only about half of all scheduled observing programmes produce a refereed publication. Programmes that result in a publication yield on average two refereed papers. B rank class Service Mode Programmes appear to be slightly less productive. Follow-up studies will investigate in more detail the parameters that influence the productivity of the Observatory.

Conformational Analysis of Stiff Chiral Polymers with End-Constraints

PubMed Central

Kim, Jin Seob; Chirikjian, Gregory S.

2010-01-01

We present a Lie-group-theoretic method for the kinematic and dynamic analysis of chiral semi-flexible polymers with end constraints. The first is to determine the minimum energy conformations of semi-flexible polymers with end constraints, and the second is to perform normal mode analysis based on the determined minimum energy conformations. In this paper, we use concepts from the theory of Lie groups and principles of variational calculus to model such polymers as inextensible or extensible chiral elastic rods with coupling between twisting and bending stiffnesses, and/or between twisting and extension stiffnesses. This method is general enough to include any stiffness and chirality parameters in the context of elastic filament models with the quadratic elastic potential energy function. As an application of this formulation, the analysis of DNA conformations is discussed. We demonstrate our method with examples of DNA conformations in which topological properties such as writhe, twist, and linking number are calculated from the results of the proposed method. Given these minimum energy conformations, we describe how to perform the normal mode analysis. The results presented here build both on recent experimental work in which DNA mechanical properties have been measured, and theoretical work in which the mechanics of non-chiral elastic rods has been studied. PMID:20198114

Modeling protein conformational changes by iterative fitting of distance constraints using reoriented normal modes.

PubMed

Zheng, Wenjun; Brooks, Bernard R

2006-06-15

Recently we have developed a normal-modes-based algorithm that predicts the direction of protein conformational changes given the initial state crystal structure together with a small number of pairwise distance constraints for the end state. Here we significantly extend this method to accurately model both the direction and amplitude of protein conformational changes. The new protocol implements a multisteps search in the conformational space that is driven by iteratively minimizing the error of fitting the given distance constraints and simultaneously enforcing the restraint of low elastic energy. At each step, an incremental structural displacement is computed as a linear combination of the lowest 10 normal modes derived from an elastic network model, whose eigenvectors are reorientated to correct for the distortions caused by the structural displacements in the previous steps. We test this method on a list of 16 pairs of protein structures for which relatively large conformational changes are observed (root mean square deviation >3 angstroms), using up to 10 pairwise distance constraints selected by a fluctuation analysis of the initial state structures. This method has achieved a near-optimal performance in almost all cases, and in many cases the final structural models lie within root mean square deviation of 1 approximately 2 angstroms from the native end state structures.

High-latitude filtering in a global grid-point model using model normal modes. [Fourier filters for synoptic weather forecasting

NASA Technical Reports Server (NTRS)

Takacs, L. L.; Kalnay, E.; Navon, I. M.

1985-01-01

A normal modes expansion technique is applied to perform high latitude filtering in the GLAS fourth order global shallow water model with orography. The maximum permissible time step in the solution code is controlled by the frequency of the fastest propagating mode, which can be a gravity wave. Numerical methods are defined for filtering the data to identify the number of gravity modes to be included in the computations in order to obtain the appropriate zonal wavenumbers. The performances of the model with and without the filter, and with a time tendency and a prognostic field filter are tested with simulations of the Northern Hemisphere winter. The normal modes expansion technique is shown to leave the Rossby modes intact and permit 3-5 day predictions, a range not possible with the other high-latitude filters.

Interference effects on guided Cherenkov emission in silicon from perpendicular, oblique, and parallel boundaries

NASA Astrophysics Data System (ADS)

Couillard, M.; Yurtsever, A.; Muller, D. A.

2010-05-01

Waveguide electromagnetic modes excited by swift electrons traversing Si slabs at normal and oblique incidence are analyzed using monochromated electron energy-loss spectroscopy and interpreted using a local dielectric theory that includes relativistic effects. At normal incidence, sharp spectral features in the visible/near-infrared optical domain are directly assigned to p -polarized modes. When the specimen is tilted, s -polarized modes, which are completely absent at normal incidence, become visible in the loss spectra. In the tilted configuration, the dispersion of p -polarized modes is also modified. For tilt angles higher than ˜50° , Cherenkov radiation, the phenomenon responsible for the excitation of waveguide modes, is expected to partially escape the silicon slab and the influence of this effect on experimental measurements is discussed. Finally, we find evidence for an interference effect at parallel Si/SiO2 interfaces, as well as a delocalized excitation of guided Cherenkov modes.

Estimation of the mechanical properties of the eye through the study of its vibrational modes

PubMed Central

2017-01-01

Measuring the eye’s mechanical properties in vivo and with minimally invasive techniques can be the key for individualized solutions to a number of eye pathologies. The development of such techniques largely relies on a computational modelling of the eyeball and, it optimally requires the synergic interplay between experimentation and numerical simulation. In Astrophysics and Geophysics the remote measurement of structural properties of the systems of their realm is performed on the basis of (helio-)seismic techniques. As a biomechanical system, the eyeball possesses normal vibrational modes encompassing rich information about its structure and mechanical properties. However, the integral analysis of the eyeball vibrational modes has not been performed yet. Here we develop a new finite difference method to compute both the spheroidal and, specially, the toroidal eigenfrequencies of the human eye. Using this numerical model, we show that the vibrational eigenfrequencies of the human eye fall in the interval 100 Hz–10 MHz. We find that compressible vibrational modes may release a trace on high frequency changes of the intraocular pressure, while incompressible normal modes could be registered analyzing the scattering pattern that the motions of the vitreous humour leave on the retina. Existing contact lenses with embebed devices operating at high sampling frequency could be used to register the microfluctuations of the eyeball shape we obtain. We advance that an inverse problem to obtain the mechanical properties of a given eye (e.g., Young’s modulus, Poisson ratio) measuring its normal frequencies is doable. These measurements can be done using non-invasive techniques, opening very interesting perspectives to estimate the mechanical properties of eyes in vivo. Future research might relate various ocular pathologies with anomalies in measured vibrational frequencies of the eye. PMID:28922351

Estimation of the mechanical properties of the eye through the study of its vibrational modes.

PubMed

Aloy, M Á; Adsuara, J E; Cerdá-Durán, P; Obergaulinger, M; Esteve-Taboada, J J; Ferrer-Blasco, T; Montés-Micó, R

2017-01-01

Measuring the eye's mechanical properties in vivo and with minimally invasive techniques can be the key for individualized solutions to a number of eye pathologies. The development of such techniques largely relies on a computational modelling of the eyeball and, it optimally requires the synergic interplay between experimentation and numerical simulation. In Astrophysics and Geophysics the remote measurement of structural properties of the systems of their realm is performed on the basis of (helio-)seismic techniques. As a biomechanical system, the eyeball possesses normal vibrational modes encompassing rich information about its structure and mechanical properties. However, the integral analysis of the eyeball vibrational modes has not been performed yet. Here we develop a new finite difference method to compute both the spheroidal and, specially, the toroidal eigenfrequencies of the human eye. Using this numerical model, we show that the vibrational eigenfrequencies of the human eye fall in the interval 100 Hz-10 MHz. We find that compressible vibrational modes may release a trace on high frequency changes of the intraocular pressure, while incompressible normal modes could be registered analyzing the scattering pattern that the motions of the vitreous humour leave on the retina. Existing contact lenses with embebed devices operating at high sampling frequency could be used to register the microfluctuations of the eyeball shape we obtain. We advance that an inverse problem to obtain the mechanical properties of a given eye (e.g., Young's modulus, Poisson ratio) measuring its normal frequencies is doable. These measurements can be done using non-invasive techniques, opening very interesting perspectives to estimate the mechanical properties of eyes in vivo. Future research might relate various ocular pathologies with anomalies in measured vibrational frequencies of the eye.

Infrared and Raman spectroscopic study of BDA-TTP [2,5-bis(1,3-dithian-2-ylidene) 1,3,4,6-tetrathiapentalene] and its charge-transfer salts

NASA Astrophysics Data System (ADS)

Uruichi, Mikio; Nakano, Chikako; Tanaka, Masayuki; Yakushi, Kyuya; Kaihatsu, Takayuki; Yamada, Jun-ichi

2008-09-01

Infrared and Raman spectra in the frequency range of 1200-1600 cm -1 were observed using BDA-TTP and (BDA-TTP)CuCl 2 crystals. The C =C stretching and CH 2 bending modes in this frequency region were assigned based on quantum chemical calculation of the normal modes by the density functional theory (DFT) method. The three C =C stretching modes of BDA-TTP showed a significant low-frequency shift upon oxidation. One of the Raman-active C =C stretching modes is strongly coupled with the charge-transfer excited state. Vibrational analysis was applied to β-(BDA-TTP) 2I 3. The infrared-active C =C stretching mode strongly suggests that the insulating state of β-(BDA-TTP) 2I 3 is characterized as a dimer-Mott state below 150 K.

Quantifying the Energy Landscape Statistics in Proteins - a Relaxation Mode Analysis

NASA Astrophysics Data System (ADS)

Cai, Zhikun; Zhang, Yang

Energy landscape, the hypersurface in the configurational space, has been a useful concept in describing complex processes that occur over a very long time scale, such as the multistep slow relaxations of supercooled liquids and folding of polypeptide chains into structured proteins. Despite extensive simulation studies, its experimental characterization still remains a challenge. To address this challenge, we developed a relaxation mode analysis (RMA) for liquids under a framework analogous to the normal mode analysis for solids. Using RMA, important statistics of the activation barriers of the energy landscape becomes accessible from experimentally measurable two-point correlation functions, e.g. using quasi-elastic and inelastic scattering experiments. We observed a prominent coarsening effect of the energy landscape. The results were further confirmed by direct sampling of the energy landscape using a metadynamics-like adaptive autonomous basin climbing computation. We first demonstrate RMA in a supercooled liquid when dynamical cooperativity emerges in the landscape-influenced regime. Then we show this framework reveals encouraging energy landscape statistics when applied to proteins.

Interference phenomena in the refraction of a surface polariton by vertical dielectric barriers

NASA Technical Reports Server (NTRS)

Shen, T. P.; Wallis, R. F.; Maradudin, A. A.; Stegeman, G. I.

1984-01-01

A normal mode analysis is used to calculate the transmission and reflection coefficients for a surface polariton propagating along the interface between a surface active medium and a dielectric and incident normally on a vertical dielectric barrier of finite thickness or a thin dielectric film of finite length. The efficiencies of conversion of the surface polariton into transmitted and reflected bulk waves are also determined. The radiation patterns associated with the latter waves are presented.

Infrared Spectrometry of Inorganic Salts

ERIC Educational Resources Information Center

Ackermann, Martin N.

1970-01-01

Describes a general chemistry experiment which uses infrared spectroscopy to analyze inorganic ions and thereby serves to introduce an important instrumental method of analysis. Presents a table of eight anions and the ammonium ion with the frequencies of their normal modes, as well as the spectra of three sulfate salts. (RR)

The Ribosome Shape Directs mRNA Translocation through Entrance and Exit Dynamics

USDA-ARS?s Scientific Manuscript database

The protein-synthesizing ribosome undergoes large motions to effect the translocation of tRNAs (transfer ribonucleic acids) and mRNA (messenger ribonucleic acid); here the domain motions of this system are explored with a coarse-grained elastic network model using normal mode analysis. Crystal struc...

Helicon normal modes in Proto-MPEX

NASA Astrophysics Data System (ADS)

Piotrowicz, P. A.; Caneses, J. F.; Green, D. L.; Goulding, R. H.; Lau, C.; Caughman, J. B. O.; Rapp, J.; Ruzic, D. N.

2018-05-01

The Proto-MPEX helicon source has been operating in a high electron density ‘helicon-mode’. Establishing plasma densities and magnetic field strengths under the antenna that allow for the formation of normal modes of the fast-wave are believed to be responsible for the ‘helicon-mode’. A 2D finite-element full-wave model of the helicon antenna on Proto-MPEX is used to identify the fast-wave normal modes responsible for the steady-state electron density profile produced by the source. We also show through the simulation that in the regions of operation in which core power deposition is maximum the slow-wave does not deposit significant power besides directly under the antenna. In the case of a simulation where a normal mode is not excited significant edge power is deposited in the mirror region. ).

Detection of rheumatoid arthritis using infrared imaging

NASA Astrophysics Data System (ADS)

Frize, Monique; Adéa, Cynthia; Payeur, Pierre; Di Primio, Gina; Karsh, Jacob; Ogungbemile, Abiola

2011-03-01

Rheumatoid arthritis (RA) is an inflammatory disease causing pain, swelling, stiffness, and loss of function in joints; it is difficult to diagnose in early stages. An early diagnosis and treatment can delay the onset of severe disability. Infrared (IR) imaging offers a potential approach to detect changes in degree of inflammation. In 18 normal subjects and 13 patients diagnosed with Rheumatoid Arthritis (RA), thermal images were collected from joints of hands, wrists, palms, and knees. Regions of interest (ROIs) were manually selected from all subjects and all parts imaged. For each subject, values were calculated from the temperature measurements: Mode/Max, Median/Max, Min/Max, Variance, Max-Min, (Mode-Mean), and Mean/Min. The data sets did not have a normal distribution, therefore non parametric tests (Kruskal-Wallis and Ranksum) were applied to assess if the data from the control group and the patient group were significantly different. Results indicate that: (i) thermal images can be detected on patients with the disease; (ii) the best joints to image are the metacarpophalangeal joints of the 2nd and 3rd fingers and the knees; the difference between the two groups was significant at the 0.05 level; (iii) the best calculations to differentiate between normal subjects and patients with RA are the Mode/Max, Variance, and Max-Min. We concluded that it is possible to reliably detect RA in patients using IR imaging. Future work will include a prospective study of normal subjects and patients that will compare IR results with Magnetic Resonance (MR) analysis.

Synthesis, crystal structure, vibrational spectra and theoretical calculations of quantum chemistry of a potential antimicrobial Meldrum's acid derivative

NASA Astrophysics Data System (ADS)

Campelo, M. J. M.; Freire, P. T. C.; Mendes Filho, J.; de Toledo, T. A.; Teixeira, A. M. R.; da Silva, L. E.; Bento, R. R. F.; Faria, J. L. B.; Pizani, P. S.; Gusmão, G. O. M.; Coutinho, H. D. M.; Oliveira, M. T. A.

2017-10-01

A new derivative of Meldrum's acid 5-((5-chloropyridin-2-ylamino)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (CYMM) of molecular formula C12H11ClN2O4 was synthesized and structurally characterized using single crystal X-ray diffraction technique. The vibrational properties of the crystal were studied by Fourier Transform infrared (FT-IR), Fourier Transform Raman (FT-Raman) techniques and theoretical calculations of quantum chemistry using Density functional theory (DFT) and Density functional perturbation theory (DFPT). A comparison with experimental spectra allowed the assignment of all the normal modes. The descriptions of the normal modes were carried by means of potential energy distribution (PED). Additionally, analysis of the antimicrobial activity and antibiotic resistance modulatory activity was carried out to evaluate the antibacterial potential of the CYMM.

Elementary solutions of coupled model equations in the kinetic theory of gases

NASA Technical Reports Server (NTRS)

Kriese, J. T.; Siewert, C. E.; Chang, T. S.

1974-01-01

The method of elementary solutions is employed to solve two coupled integrodifferential equations sufficient for determining temperature-density effects in a linearized BGK model in the kinetic theory of gases. Full-range completeness and orthogonality theorems are proved for the developed normal modes and the infinite-medium Green's function is constructed as an illustration of the full-range formalism. The appropriate homogeneous matrix Riemann problem is discussed, and half-range completeness and orthogonality theorems are proved for a certain subset of the normal modes. The required existence and uniqueness theorems relevant to the H matrix, basic to the half-range analysis, are proved, and an accurate and efficient computational method is discussed. The half-space temperature-slip problem is solved analytically, and a highly accurate value of the temperature-slip coefficient is reported.

Numerical computation of linear instability of detonations

NASA Astrophysics Data System (ADS)

Kabanov, Dmitry; Kasimov, Aslan

2017-11-01

We propose a method to study linear stability of detonations by direct numerical computation. The linearized governing equations together with the shock-evolution equation are solved in the shock-attached frame using a high-resolution numerical algorithm. The computed results are processed by the Dynamic Mode Decomposition technique to generate dispersion relations. The method is applied to the reactive Euler equations with simple-depletion chemistry as well as more complex multistep chemistry. The results are compared with those known from normal-mode analysis. We acknowledge financial support from King Abdullah University of Science and Technology.

Secular instabilities of Keplerian stellar discs

NASA Astrophysics Data System (ADS)

Kaur, Karamveer; Kazandjian, Mher V.; Sridhar, S.; Touma, Jihad R.

2018-05-01

We present idealized models of a razor-thin, axisymmetric, Keplerian stellar disc around a massive black hole, and study non-axisymmetric secular instabilities in the absence of either counter-rotation or loss cones. These discs are prograde mono-energetic waterbags, whose phase-space distribution functions are constant for orbits within a range of eccentricities (e) and zero outside this range. The linear normal modes of waterbags are composed of sinusoidal disturbances of the edges of distribution function in phase space. Waterbags that include circular orbits (polarcaps) have one stable linear normal mode for each azimuthal wavenumber m. The m = 1 mode always has positive pattern speed and, for polarcaps consisting of orbits with e < 0.9428, only the m = 1 mode has positive pattern speed. Waterbags excluding circular orbits (bands) have two linear normal modes for each m, which can be stable or unstable. We derive analytical expressions for the instability condition, pattern speeds, growth rates, and normal mode structure. Narrow bands are unstable to modes with a wide range in m. Numerical simulations confirm linear theory and follow the non-linear evolution of instabilities. Long-time integration suggests that instabilities of different m grow, interact non-linearly, and relax collisionlessly to a coarse-grained equilibrium with a wide range of eccentricities.

Upper-Level Waves of Synoptic Scale at Midlatitudes

NASA Astrophysics Data System (ADS)

Rivest, Chantal

1990-01-01

Upper-level waves of synoptic scale are important dynamical entities at midlatitudes. They often induce surface cyclogenesis (cf. Peterssen and Smebye, 1971), and their life duration is typically longer than time scales for disruption by the ambient shear (Sanders, 1988). The objectives of the present thesis are to explain the maintenance and genesis of upper-level synoptic-scale waves in the midlatitude flow. We develop an analytical model of waves on generalized Eady basic states that have uniform tropospheric and stratospheric potential vorticity, but allow for the decay of density with height. The Eady basic state represents the limiting case of infinite stratospheric stability and constant density. We find that the Eady normal mode characteristics hold in the presence of realistic tropopause and stratosphere. In particular, the basic states studied support at the synoptic scale upper-level normal modes. These modes provide simple models for the dynamics of upper-level synoptic-scale waves, as waves supported by the large latitudinal gradients of potential vorticity at the tropopause. In the presence of infinitesimal positive tropospheric gradients of potential vorticity, the upper-level normal mode solutions no longer exist, as was demonstrated in Green (1960). Disappearance of the normal mode solution when a parameter changes slightly represents a dilemma that we seek to understand. We examine what happens to the upper-level normal modes in the presence of tropospheric gradients of potential vorticity in a series of initial -value experiments. Our results show that the normal modes become slowly decaying quasi-modes. Mathematically the quasi-modes consist of a superposition of singular modes sharply peaked in the phase speed domain, and their decay proceeds as the modes interfere with one another. We repeat these experiments in basic states with a smooth tropopause in the presence of tropospheric and stratospheric gradients, and similar results are obtained. Basic states with positive tropospheric and stratospheric gradients of potential vorticity are found to support upper-level synoptic-scale waves for time scales consistent with observations. Following Farrell (1989), we then identify a class of near optimal initial conditions for the excitation of upper-level waves. The initial conditions consist of upper -tropospheric disturbances that lean against the shear. They strongly excite upper-level waves not only in the absence of tropospheric potential vorticity gradients, but also in their presence. This result demonstrates that quasi -modes are as likely to emerge from favorably configured initial conditions as real normal modes, although their excitation is followed by a slow decay. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.).

FIBER AND INTEGRATED OPTICS: Propagation of radiation in a light-induced active waveguide

NASA Astrophysics Data System (ADS)

Afanas'ev, Anatolii A.; Samson, B. A.; Drits, V. V.; Yukhimenko, S. I.; Yakite, R. V.

1990-10-01

An investigation is reported of the properties of the normal modes of an active light-induced waveguide. It is shown that, in contrast to a dielectric waveguide, the presence of the active component may increase considerably the number of the normal modes and the angles of their scattering. In the case of an active light-induced waveguide in the form of a thin filament the normal modes exist and are amplified only in the case when the nonlinear correction to the refractive index is positive.

Normal-Mode Splitting in a Weakly Coupled Optomechanical System

NASA Astrophysics Data System (ADS)

Rossi, Massimiliano; Kralj, Nenad; Zippilli, Stefano; Natali, Riccardo; Borrielli, Antonio; Pandraud, Gregory; Serra, Enrico; Di Giuseppe, Giovanni; Vitali, David

2018-02-01

Normal-mode splitting is the most evident signature of strong coupling between two interacting subsystems. It occurs when two subsystems exchange energy between themselves faster than they dissipate it to the environment. Here we experimentally show that a weakly coupled optomechanical system at room temperature can manifest normal-mode splitting when the pump field fluctuations are antisquashed by a phase-sensitive feedback loop operating close to its instability threshold. Under these conditions the optical cavity exhibits an effectively reduced decay rate, so that the system is effectively promoted to the strong coupling regime.

Breathing Mode in Complex Plasmas

NASA Astrophysics Data System (ADS)

Fujioka, K.; Henning, C.; Ludwig, P.; Bonitz, M.; Melzer, A.; Vitkalov, S.

2007-11-01

The breathing mode is a fundamental normal mode present in Coulomb systems, and may have utility in identifying particle charge and the Debye length of certain systems. The question remains whether this mode can be extended to strongly coupled Yukawa balls [1]. These systems are characterized by particles confined within a parabolic potential well and interacting through a shielded Coulomb potential [2,3]. The breathing modes for a variety of systems in 1, 2, and 3 dimensions are computed by solving the eigenvalue problem given by the dynamical (Hesse) matrix. These results are compared to theoretical investigations that assume a strict definition for a breathing mode within the system, and an analysis is made of the most fitting model to utilize in the study of particular systems of complex plasmas [1,4]. References [1] T.E. Sheridan, Phys. of Plasmas. 13, 022106 (2006)[2] C. Henning et al., Phys. Rev. E 74, 056403 (2006)[3] M. Bonitz et al., Phys. Rev. Lett. 96, 075001 (2006)[4] C. Henning et al., submitted for publication

The interplay of protein and solvent picosecond dynamics: Experimental and theoretical studies

NASA Astrophysics Data System (ADS)

He, Yunfen

Terahertz gap is located between microwaves and infrared. THz-TDS is based on the generation of subpicosecond terahertz pulses using ultrashort laser pulses with pulse durations of a few femtoseconds. From the spectroscopic point of view terahertz radiation excites the low frequency vibrations of molecules. Terahertz spectroscopy provides a new way to study protein dynamics in this critical frequency range. The strong temperature dependence of molecular flexibility near 200 K for proteins and polynucleotides hydrated above 30% by weight, dynamical transition, is one of the most significant phenomena of biomolecular dynamics. Measurements of the dynamical transition were performed for native, fully denatured and unstructured polypeptides using THz-TDS. The results reveal that the dynamical transition is independent of either tertiary or secondary structure. The transition are also found for shorter chain alanine peptides down to penta-alanine, which indicates that a quantitative predictive theory for the temperature dependence lies in the understanding of the interaction of the side chains of the poly peptide or poly nucleotide with the biological water. The far infrared vibrational modes can be calculated using harmonic or anharmonic normal mode analysis, and the resulting Density of States (DOS) strongly resembles the measured absorbance. A large contrast in the terahertz dielectric response between oxidized and reduced cytochrome c has lready been observed experimentally. This large contrast has been associated with a change in the collective structural motions that related to protein flexibility. Molecular simulation results from quasiharmonic analysis and dipole-dipole correlation analysis are compared with the measurements to determine the relative contribution of correlated motions and diffusive motions to the measured dielectric response. The measured hydration dependence is reproduced by hydration dependence of quasiharmonic normal modes, but these modes calculations do not reproduce the oxidation dependence. Whereas dipole-dipole correlation analysis reproduces the oxidation dependence at the lowest hydration level, but surprisingly do not capture the hydration dependence. These results suggest that the hydration dependence in the THz response does in fact arise from changes in the vibrational modes, and the oxidation dependence arises from relaxational motions.

Evaluation of Geometrically Nonlinear Reduced Order Models with Nonlinear Normal Modes

DOE PAGES

Kuether, Robert J.; Deaner, Brandon J.; Hollkamp, Joseph J.; ...

2015-09-15

Several reduced-order modeling strategies have been developed to create low-order models of geometrically nonlinear structures from detailed finite element models, allowing one to compute the dynamic response of the structure at a dramatically reduced cost. But, the parameters of these reduced-order models are estimated by applying a series of static loads to the finite element model, and the quality of the reduced-order model can be highly sensitive to the amplitudes of the static load cases used and to the type/number of modes used in the basis. Our paper proposes to combine reduced-order modeling and numerical continuation to estimate the nonlinearmore » normal modes of geometrically nonlinear finite element models. Not only does this make it possible to compute the nonlinear normal modes far more quickly than existing approaches, but the nonlinear normal modes are also shown to be an excellent metric by which the quality of the reduced-order model can be assessed. Hence, the second contribution of this work is to demonstrate how nonlinear normal modes can be used as a metric by which nonlinear reduced-order models can be compared. Moreover, various reduced-order models with hardening nonlinearities are compared for two different structures to demonstrate these concepts: a clamped–clamped beam model, and a more complicated finite element model of an exhaust panel cover.« less

ASTROP2 users manual: A program for aeroelastic stability analysis of propfans

NASA Technical Reports Server (NTRS)

Narayanan, G. V.; Kaza, K. R. V.

1991-01-01

A user's manual is presented for the aeroelastic stability and response of propulsion systems computer program called ASTROP2. The ASTROP2 code preforms aeroelastic stability analysis of rotating propfan blades. This analysis uses a two-dimensional, unsteady cascade aerodynamics model and a three-dimensional, normal-mode structural model. Analytical stability results from this code are compared with published experimental results of a rotating composite advanced turboprop model and of nonrotating metallic wing model.

Channel branching ratios in CH2CN- photodetachment: Rotational structure and vibrational energy redistribution in autodetachment

NASA Astrophysics Data System (ADS)

Lyle, Justin; Wedig, Olivia; Gulania, Sahil; Krylov, Anna I.; Mabbs, Richard

2017-12-01

We report photoelectron spectra of CH2CN-, recorded at photon energies between 13 460 and 15 384 cm-1, which show rapid intensity variations in particular detachment channels. The branching ratios for various spectral features reveal rotational structure associated with autodetachment from an intermediate anion state. Calculations using equation-of-motion coupled-cluster method with single and double excitations reveal the presence of two dipole-bound excited anion states (a singlet and a triplet). The computed oscillator strength for the transition to the singlet dipole-bound state provides an estimate of the autodetachment channel contribution to the total photoelectron yield. Analysis of the different spectral features allows identification of the dipole-bound and neutral vibrational levels involved in the autodetachment processes. For the most part, the autodetachment channels are consistent with the vibrational propensity rule and normal mode expectation. However, examination of the rotational structure shows that autodetachment from the ν3 (v = 1 and v = 2) levels of the dipole-bound state displays behavior counter to the normal mode expectation with the final state vibrational level belonging to a different mode.

A normal mode treatment of semi-diurnal body tides on an aspherical, rotating and anelastic Earth

NASA Astrophysics Data System (ADS)

Lau, Harriet C. P.; Yang, Hsin-Ying; Tromp, Jeroen; Mitrovica, Jerry X.; Latychev, Konstantin; Al-Attar, David

2015-08-01

Normal mode treatments of the Earth's body tide response were developed in the 1980s to account for the effects of Earth rotation, ellipticity, anelasticity and resonant excitation within the diurnal band. Recent space-geodetic measurements of the Earth's crustal displacement in response to luni-solar tidal forcings have revealed geographical variations that are indicative of aspherical deep mantle structure, thus providing a novel data set for constraining deep mantle elastic and density structure. In light of this, we make use of advances in seismic free oscillation literature to develop a new, generalized normal mode theory for the tidal response within the semi-diurnal and long-period tidal band. Our theory involves a perturbation method that permits an efficient calculation of the impact of aspherical structure on the tidal response. In addition, we introduce a normal mode treatment of anelasticity that is distinct from both earlier work in body tides and the approach adopted in free oscillation seismology. We present several simple numerical applications of the new theory. First, we compute the tidal response of a spherically symmetric, non-rotating, elastic and isotropic Earth model and demonstrate that our predictions match those based on standard Love number theory. Second, we compute perturbations to this response associated with mantle anelasticity and demonstrate that the usual set of seismic modes adopted for this purpose must be augmented by a family of relaxation modes to accurately capture the full effect of anelasticity on the body tide response. Finally, we explore aspherical effects including rotation and we benchmark results from several illustrative case studies of aspherical Earth structure against independent finite-volume numerical calculations of the semi-diurnal body tide response. These tests confirm the accuracy of the normal mode methodology to at least the level of numerical error in the finite-volume predictions. They also demonstrate that full coupling of normal modes, rather than group coupling, is necessary for accurate predictions of the body tide response.

Quasi-normal modes from non-commutative matrix dynamics

NASA Astrophysics Data System (ADS)

Aprile, Francesco; Sanfilippo, Francesco

2017-09-01

We explore similarities between the process of relaxation in the BMN matrix model and the physics of black holes in AdS/CFT. Focusing on Dyson-fluid solutions of the matrix model, we perform numerical simulations of the real time dynamics of the system. By quenching the equilibrium distribution we study quasi-normal oscillations of scalar single trace observables, we isolate the lowest quasi-normal mode, and we determine its frequencies as function of the energy. Considering the BMN matrix model as a truncation of N=4 SYM, we also compute the frequencies of the quasi-normal modes of the dual scalar fields in the AdS5-Schwarzschild background. We compare the results, and we finda surprising similarity.

A Unique Self-Sensing, Self-Actuating AFM Probe at Higher Eigenmodes

PubMed Central

Wu, Zhichao; Guo, Tong; Tao, Ran; Liu, Leihua; Chen, Jinping; Fu, Xing; Hu, Xiaotang

2015-01-01

With its unique structure, the Akiyama probe is a type of tuning fork atomic force microscope probe. The long, soft cantilever makes it possible to measure soft samples in tapping mode. In this article, some characteristics of the probe at its second eigenmode are revealed by use of finite element analysis (FEA) and experiments in a standard atmosphere. Although the signal-to-noise ratio in this environment is not good enough, the 2 nm resolution and 0.09 Hz/nm sensitivity prove that the Akiyama probe can be used at its second eigenmode under FM non-contact mode or low amplitude FM tapping mode, which means that it is easy to change the measuring method from normal tapping to small amplitude tapping or non-contact mode with the same probe and equipment. PMID:26580619

Guided waves by axisymmetric and non-axisymmetric surface loading on hollow cylinders

PubMed

Shin; Rose

1999-06-01

Guided waves generated by axisymmetric and non-axisymmetric surface loading on a hollow cylinder are studied. For the theoretical analysis of the superposed guided waves, a normal mode concept is employed. The amplitude factors of individual guided wave modes are studied with respect to varying surface pressure loading profiles. Both theoretical and experimental focus is given to the guided waves generated by both axisymmetric and non-axisymmetric excitation. For the experiments, a comb transducer and high power tone burst function generator system are used on a sample Inconel tube. Surface loading conditions, such as circumferential loading angles and axial loading lengths, are used with the frequency and phase velocity to control the axisymmetric and non-axisymmetric mode excitations. The experimental study demonstrates the use of a practical non-axisymmetric partial loading technique in generating axisymmetric modes, particularly useful in the inspection of tubing and piping with limited circumferential access. From both theoretical and experimental studies, it also could be said that the amount of flexural modes reflected from a defect contains information on the reflector's circumferential angle, as well as potentially other classification and sizing feature information. The axisymmetric and non-axisymmetric guided wave modes should both be carefully considered for improvement of the overall analysis of guided waves generated in hollow cylinders.

Combined mode I stress intensity factors of slanted cracks

NASA Astrophysics Data System (ADS)

Ismail, A. E.; Rahman, M. Q. Abdul; Ghazali, M. Z. Mohd; Zulafif Rahim, M.; Rasidi Ibrahim, M.; Fahrul Hassan, Mohd; Nor, Nik Hisyamudin Muhd; Ariffin, A. M. T.; Zaini Yunos, Muhamad

2017-08-01

The solutions of stress intensity factors (SIFs) for slanted cracks in plain strain plate are hard to find in open literature. There are some previous solutions of SIFs available, however the studies are not completed except for the case of plain stress. The slanted cracks are modelled numerically using ANSYS finite element program. There are ten slanted angles and seven relative crack depths are used and the plate contains cracks which is assumed to fulfil the plain strain condition. The plate is then stressed under tension and bending loading and the SIFs are determined according to the displacement extrapolation method. Based on the numerical analysis, both slanted angles and relative crack length, a/L played an important role in determining the modes I and II SIFs. As expected the SIFs increased when a/L is increased. Under tension force, the introduction of slanted angles increased the SIFs. Further increment of angles reduced the SIFs however they are still higher than the SIFs obtained using normal cracks. Under bending moment, the present of slanted angles are significantly reduced the SIFs compared with the normal cracks. Under similar loading, mode II SIFs increased as function of a/L and slanted angles where increasing such parameters increasing the mode II SIFs.

Spectroradiometric calibration of the Thematic Mapper and Multispectral Scanner system. [White Sands, New Mexico

NASA Technical Reports Server (NTRS)

Palmer, J. M. (Principal Investigator); Slater, P. N.

1984-01-01

The newly built Caste spectropolarimeters gave satisfactory performance during tests in the solar radiometer and helicopter modes. A bandwidth normalization technique based on analysis of the moments of the spectral responsivity curves was used to analyze the spectral bands of the MSS and TM subsystems of LANDSAT 4 and 5 satellites. Results include the effective wavelength, the bandpass, the wavelength limits, and the normalized responsivity for each spectral channel. Temperature coefficients for TM PF channel 6 were also derived. The moments normalization method used yields sensor parameters whose derivation is independent of source characteristics (i.e., incident solar spectral irradiance, atmospheric transmittance, or ground reflectance). The errors expected using these parameters are lower than those expected using other normalization methods.

Comparison of liquid and supercritical fluid chromatography mobile phases for enantioselective separations on polysaccharide stationary phases.

PubMed

Khater, Syame; Lozac'h, Marie-Anne; Adam, Isabelle; Francotte, Eric; West, Caroline

2016-10-07

Analysis and production of enantiomerically pure compounds is a major topic of interest when active pharmaceutical ingredients are concerned. Enantioselective chromatography has become a favourite both at the analytical and preparative scales. High-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) are dominating the scene and are often seen as complementary techniques. Nowadays, for economic and ecologic reasons, SFC may be preferred over normal-phase HPLC (NPLC) as it allows significant reductions in solvent consumption. However, the transfer of NPLC methods to SFC is not always straightforward. In this study, we compare the retention of achiral molecules and separation of enantiomers under supercritical fluid (carbon dioxide with ethanol or isopropanol) and liquid normal-phase (heptane with ethanol or isopropanol) elution modes with polysaccharide stationary phases in order to explore the differences between the retention and enantioseparation properties between the two modes. Chemometric methods (namely quantitative structure-retention relationships and discriminant analysis) are employed to compare the results obtained on a large set of analytes (171 achiral probes and 97 racemates) and gain some understanding on the retention and separation mechanisms. The results indicate that, contrary to popular belief, carbon dioxide - solvent SFC mobile phases are often weaker eluents than liquid mobile phases. It appears that SFC and NPLC elution modes provide different retention mechanisms. While some enantioseparations are unaffected, facilitating the transfer between the two elution modes, other enantioseparations may be drastically different due to different types and strength of interactions contributing to enantioselectivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Modal strain energies in COSMIC NASTRAN

NASA Technical Reports Server (NTRS)

Snyder, B. D.; Venkayya, V. B.

1989-01-01

A computer program was developed to take a NASTRAN output file from a normal modes analysis and calculate the modal strain energies of selected elements. The FORTRAN program can determine the modal strain energies for CROD, CBAR, CELAS, CTRMEM, CQDMEM2, and CSHEAR elements. Modal strain energies are useful in estimating damping in structures.

Optimal Disturbances in Boundary Layers Subject to Streamwise Pressure Gradient

NASA Technical Reports Server (NTRS)

Tumin, Anatoli; Ashpis, David E.

2003-01-01

Laminar-turbulent transition in shear flows is still an enigma in the area of fluid mechanics. The conventional explanation of the phenomenon is based on the instability of the shear flow with respect to infinitesimal disturbances. The conventional hydrodynamic stability theory deals with the analysis of normal modes that might be unstable. The latter circumstance is accompanied by an exponential growth of the disturbances that might lead to laminar-turbulent transition. Nevertheless, in many cases, the transition scenario bypasses the exponential growth stage associated with the normal modes. This type of transition is called bypass transition. An understanding of the phenomenon has eluded us to this day. One possibility is that bypass transition is associated with so-called algebraic (non-modal) growth of disturbances in shear flows. In the present work, an analysis of the optimal disturbances/streamwise vortices associated with the transient growth mechanism is performed for boundary layers in the presence of a streamwise pressure gradient. The theory will provide the optimal spacing of the control elements in the spanwise direction and their placement in the streamwise direction.

A blood pressure monitor with robust noise reduction system under linear cuff inflation and deflation.

PubMed

Usuda, Takashi; Kobayashi, Naoki; Takeda, Sunao; Kotake, Yoshifumi

2010-01-01

We have developed the non-invasive blood pressure monitor which can measure the blood pressure quickly and robustly. This monitor combines two measurement mode: the linear inflation and the linear deflation. On the inflation mode, we realized a faster measurement with rapid inflation rate. On the deflation mode, we realized a robust noise reduction. When there is neither noise nor arrhythmia, the inflation mode incorporated on this monitor provides precise, quick and comfortable measurement. Once the inflation mode fails to calculate appropriate blood pressure due to body movement or arrhythmia, then the monitor switches automatically to the deflation mode and measure blood pressure by using digital signal processing as wavelet analysis, filter bank, filter combined with FFT and Inverse FFT. The inflation mode succeeded 2440 measurements out of 3099 measurements (79%) in an operating room and a rehabilitation room. The new designed blood pressure monitor provides the fastest measurement for patient with normal circulation and robust measurement for patients with body movement or severe arrhythmia. Also this fast measurement method provides comfortableness for patients.

Non-Gaussian structure of B-mode polarization after delensing

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

Namikawa, Toshiya; Nagata, Ryo, E-mail: namikawa@slac.stanford.edu, E-mail: rnagata@post.kek.jp

2015-10-01

The B-mode polarization of the cosmic microwave background on large scales has been considered as a probe of gravitational waves from the cosmic inflation. Ongoing and future experiments will, however, suffer from contamination due to the B-modes of non-primordial origins, one of which is the lensing induced B-mode polarization. Subtraction of the lensing B-modes, usually referred to as delensing, will be required for further improvement of detection sensitivity of the gravitational waves. In such experiments, knowledge of statistical properties of the B-modes after delensing is indispensable to likelihood analysis particularly because the lensing B-modes are known to be non-Gaussian. Inmore » this paper, we study non-Gaussian structure of the delensed B-modes on large scales, comparing it with that of the lensing B-modes. In particular, we investigate the power spectrum correlation matrix and the probability distribution function (PDF) of the power spectrum amplitude. Assuming an experiment in which the quadratic delensing is an almost optimal method, we find that delensing reduces correlations of the lensing B-mode power spectra between different multipoles, and that the PDF of the power spectrum amplitude is well described as a normal distribution function with a variance larger than that in the case of a Gaussian field. These features are well captured by an analytic model based on the 4th order Edgeworth expansion. As a consequence of the non-Gaussianity, the constraint on the tensor-to-scalar ratio after delensing is degraded within approximately a few percent, which depends on the multipole range included in the analysis.« less

Non-Gaussian structure of B-mode polarization after delensing

NASA Astrophysics Data System (ADS)

Namikawa, Toshiya; Nagata, Ryo

2015-10-01

The B-mode polarization of the cosmic microwave background on large scales has been considered as a probe of gravitational waves from the cosmic inflation. Ongoing and future experiments will, however, suffer from contamination due to the B-modes of non-primordial origins, one of which is the lensing induced B-mode polarization. Subtraction of the lensing B-modes, usually referred to as delensing, will be required for further improvement of detection sensitivity of the gravitational waves. In such experiments, knowledge of statistical properties of the B-modes after delensing is indispensable to likelihood analysis particularly because the lensing B-modes are known to be non-Gaussian. In this paper, we study non-Gaussian structure of the delensed B-modes on large scales, comparing it with that of the lensing B-modes. In particular, we investigate the power spectrum correlation matrix and the probability distribution function (PDF) of the power spectrum amplitude. Assuming an experiment in which the quadratic delensing is an almost optimal method, we find that delensing reduces correlations of the lensing B-mode power spectra between different multipoles, and that the PDF of the power spectrum amplitude is well described as a normal distribution function with a variance larger than that in the case of a Gaussian field. These features are well captured by an analytic model based on the 4th order Edgeworth expansion. As a consequence of the non-Gaussianity, the constraint on the tensor-to-scalar ratio after delensing is degraded within approximately a few percent, which depends on the multipole range included in the analysis.

Non-Gaussian structure of B-mode polarization after delensing

DOE PAGES

Namikawa, Toshiya; Nagata, Ryo

2015-10-01

The B-mode polarization of the cosmic microwave background on large scales has been considered as a probe of gravitational waves from the cosmic inflation. Ongoing and future experiments will, however, suffer from contamination due to the B-modes of non-primordial origins, one of which is the lensing induced B-mode polarization. Subtraction of the lensing B-modes, usually referred to as delensing, will be required for further improvement of detection sensitivity of the gravitational waves. In such experiments, knowledge of statistical properties of the B-modes after delensing is indispensable to likelihood analysis particularly because the lensing B-modes are known to be non-Gaussian. Inmore » this paper, we study non-Gaussian structure of the delensed B-modes on large scales, comparing it with that of the lensing B-modes. In particular, we investigate the power spectrum correlation matrix and the probability distribution function (PDF) of the power spectrum amplitude. Assuming an experiment in which the quadratic delensing is an almost optimal method, we find that delensing reduces correlations of the lensing B-mode power spectra between different multipoles, and that the PDF of the power spectrum amplitude is well described as a normal distribution function with a variance larger than that in the case of a Gaussian field. These features are well captured by an analytic model based on the 4th order Edgeworth expansion. Furthermore, as a consequence of the non-Gaussianity, the constraint on the tensor-to-scalar ratio after delensing is degraded within approximately a few percent, which depends on the multipole range included in the analysis.« less

Atomic force microscopy contact, tapping, and jumping modes for imaging biological samples in liquids

NASA Astrophysics Data System (ADS)

Moreno-Herrero, F.; Colchero, J.; Gómez-Herrero, J.; Baró, A. M.

2004-03-01

The capabilities of the atomic force microscope for imaging biomolecules under physiological conditions has been systematically investigated. Contact, dynamic, and jumping modes have been applied to four different biological systems: DNA, purple membrane, Alzheimer paired helical filaments, and the bacteriophage φ29. These samples have been selected to cover a wide variety of biological systems in terms of sizes and substrate contact area, which make them very appropriate for the type of comparative studies carried out in the present work. Although dynamic mode atomic force microscopy is clearly the best choice for imaging soft samples in air, in liquids there is not a leading technique. In liquids, the most appropriate imaging mode depends on the sample characteristics and preparation methods. Contact or dynamic modes are the best choices for imaging molecular assemblies arranged as crystals such as the purple membrane. In this case, the advantage of image acquisition speed predominates over the disadvantage of high lateral or normal force. For imaging individual macromolecules, which are weakly bonded to the substrate, lateral and normal forces are the relevant factors, and hence the jumping mode, an imaging mode which minimizes lateral and normal forces, is preferable to other imaging modes.

Two Populations of Sunspots: Differential Rotation

NASA Astrophysics Data System (ADS)

Nagovitsyn, Yu. A.; Pevtsov, A. A.; Osipova, A. A.

2018-03-01

To investigate the differential rotation of sunspot groups using the Greenwich data, we propose an approach based on a statistical analysis of the histograms of particular longitudinal velocities in different latitude intervals. The general statistical velocity distributions for all such intervals are shown to be described by two rather than one normal distribution, so that two fundamental rotation modes exist simultaneously: fast and slow. The differentiality of rotation for the modes is the same: the coefficient at sin2 in Faye's law is 2.87-2.88 deg/day, while the equatorial rotation rates differ significantly, 0.27 deg/day. On the other hand, an analysis of the longitudinal velocities for the previously revealed two differing populations of sunspot groups has shown that small short-lived groups (SSGs) are associated with the fast rotation mode, while large long-lived groups (LLGs) are associated with both fast and slow modes. The results obtained not only suggest a real physical difference between the two populations of sunspots but also give new empirical data for the development of a dynamo theory, in particular, for the theory of a spatially distributed dynamo.

Normal Modes of a Lagrangian System Constrained in a Potential Well.

DTIC Science & Technology

1983-12-01

A’ -137 948 NORMAL MODES OF A LFHbRANGIAN SYSTEM CONSTRAINED INvi P0TENTIAL WELL(U WISCONSNN UNIV-MADISON MATHEMATICS RESEARCH CENTER V EN DEC F1...Carolina 27709 DT FLE OP Y UNIVERSITY OF WISCONSIN-MADISON MATHEMATICS RESEARCH CENTER NORMAL MODES OF A LAGRANGIAN SYSTEM CONSTRAINED IN A POTENTIAL WELL...respect to the norm lYE [f i + 2 yi )dtl/ 0 Since H I(S’ 1 n’) C CO(S, fle ), then the set A 1 0 is an open set in H1 (lf’) The periodic solution of

Isolator-combustor interaction in a dual-mode scramjet engine

NASA Technical Reports Server (NTRS)

Pratt, David T.; Heiser, William H.

1993-01-01

A constant-area diffuser, or 'isolator', is required in both the ramjet and scramjet operating regimes of a dual-mode engine configuration in order to prevent unstarts due to pressure feedback from the combustor. Because the nature of the combustor-isolator interaction is different in the two operational modes, however, attention is presently given to the use of thermal vs kinetic energy coordinates for these interaction processes' visualization. The results of the analysis thus conducted indicate that the isolator requires severe flow separation at combustor entry, and that its entropy-generating characteristics are more severe than an equivalent oblique shock. A constant-area diffuser is only marginally able to contain the equivalent normal shock required for subsonic combustor entry.

Experimental investigation of internal tides generated by finite-height topography

NASA Astrophysics Data System (ADS)

Wang, Shuya; Chen, Xu; Wang, Jinhu; Meng, Jing

2018-06-01

Internal tides generated by finite-height topography are investigated in the laboratory, and the particle image velocimetry (PIV) technique is applied to measure the velocity fields. The energy, energy flux, and vertical mode structure of the internal tides are calculated and analyzed. The experimental results indicate that the strength of the wave field is mainly affected by the normalized topography height. The rays radiated from the taller topography are wider than those radiated from the lower topography. Both the experimental and theoretical results indicate that the normalized energy and energy flux of the internal tides are mainly determined by the normalized topography height, and the increase of the two quantities follows a quadratic function, and they almost remain unchanged with different normalized frequencies except for higher frequency. The percentage of energy for mode-1 and mode-2 internal tides is determined not only by frequency but also by topography height. In addition, an "inherent normalized frequency" is observed in the experiment, at which the percentage of energy for mode 1 and mode 2 does not vary with topography height. The decay rate of internal tide energy in the near field and far field is also estimated, with average values of 36.5 and 7.5%, respectively.

Constrained maximum likelihood modal parameter identification applied to structural dynamics

NASA Astrophysics Data System (ADS)

El-Kafafy, Mahmoud; Peeters, Bart; Guillaume, Patrick; De Troyer, Tim

2016-05-01

A new modal parameter estimation method to directly establish modal models of structural dynamic systems satisfying two physically motivated constraints will be presented. The constraints imposed in the identified modal model are the reciprocity of the frequency response functions (FRFs) and the estimation of normal (real) modes. The motivation behind the first constraint (i.e. reciprocity) comes from the fact that modal analysis theory shows that the FRF matrix and therefore the residue matrices are symmetric for non-gyroscopic, non-circulatory, and passive mechanical systems. In other words, such types of systems are expected to obey Maxwell-Betti's reciprocity principle. The second constraint (i.e. real mode shapes) is motivated by the fact that analytical models of structures are assumed to either be undamped or proportional damped. Therefore, normal (real) modes are needed for comparison with these analytical models. The work done in this paper is a further development of a recently introduced modal parameter identification method called ML-MM that enables us to establish modal model that satisfies such motivated constraints. The proposed constrained ML-MM method is applied to two real experimental datasets measured on fully trimmed cars. This type of data is still considered as a significant challenge in modal analysis. The results clearly demonstrate the applicability of the method to real structures with significant non-proportional damping and high modal densities.

Stiffening of flexible SUMO1 protein upon peptide-binding: Analysis with anisotropic network model.

PubMed

Sarkar, Ranja

2018-01-01

SUMO (small ubiquitin-like modifier) proteins interact with a large number of target proteins via a key regulatory event called sumoylation that encompasses activation, conjugation and ligation of SUMO proteins through specific E1, E2, and E3-type enzymes respectively. Single-molecule atomic force microscopic (AFM) experiments performed to unravel bound SUMO1 along its NC termini direction reveal that E3-ligases (in the form of small peptides) increase mechanical stability (along the axis) of the flexible protein upon binding. The experimental results are expected to correlate with the intrinsic flexibility of bound SUMO1 protein in the native state i.e., the bound conformation of SUMO1 without the binding peptide. The native protein flexibility/stiffness can be measured as a spring constant by normal mode analysis. In the present study, protein normal modes are computed from the protein structural data (as input from protein databank) via a simple anisotropic network model (ANM). ANM is computationally inexpensive and hence, can be explored to investigate and compare the native conformational dynamics of unbound and bound (without the binding partner) structures, if the corresponding structural data (NMR/X-ray) are available. The paper illustrates that SUMO1 stiffens (native flexibility decreases) along the NC termini (end-to-end) direction of the protein upon binding to small peptides; however, the degree of stiffening is peptide sequence-specific. The theoretical results are demonstrated for NMR structures of unbound SUMO1 and that bound to two peptides having short amino acid motifs and of similar size, one being an M-IR2 peptide derived from RanBP2 protein and the other one derived from PIASX protein. The peptide derived from PIASX stiffens SUMO1 remarkably which is evident from an atomic-level normal mode analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

Dielectric and vibrational properties of amino acids

NASA Astrophysics Data System (ADS)

Tulip, P. R.; Clark, S. J.

2004-09-01

We calculate polarizability tensors and normal mode frequencies for the amino acids alanine, leucine, isoleucine, and valine using density functional perturbation theory implemented within the plane wave pseudopotential framework. It is found that the behavior of the electron density under external fields depends to a large extent on the geometrical structure of the molecule in question, rather than simply on the constituent functional groups. The normal modes are able to help distinguish between the different types of intramolecular hydrogen bonding present, and help to explain why leucine is found in the zwitterionic form for the gaseous phase. Calculated IR spectra show a marked difference between those obtained for zwitterionic and nonzwitterionic molecules. These differences can be attributed to the different chemical and hydrogen bonds present. Effective dynamical charges are calculated, and compared to atomic charges obtained from Mulliken population analysis. It is found that disagreement exists, largely due to the differing origins of these quantities.

Theory of psychological adaptive modes.

PubMed

Lehti, Juha

2016-05-01

When an individual is facing a stressor and normal stress-response mechanism cannot guarantee sufficient adaptation, special emotional states, adaptive modes, are activated (for example a depressive reaction). Adaptive modes are involuntary states of mind, they are of comprehensive nature, they interfere with normal functioning, and they cannot be repressed or controlled the same way as many emotions. Their transformational nature differentiates them from other emotional states. The object of the adaptive mode is to optimize the problem-solving abilities according to the situation that has provoked the mode. Cognitions and emotions during the adaptive mode are different than in a normal mental state. These altered cognitions and emotional reactions guide the individual to use the correct coping skills in order to deal with the stressor. Successful adaptation will cause the adaptive mode to fade off since the adaptive mode is no longer necessary, and the process as a whole will lead to raised well-being. However, if the adaptation process is inadequate, then the transformation period is prolonged, and the adaptive mode will turn into a dysfunctional state. Many psychiatric disorders are such maladaptive processes. The maladaptive processes can be turned into functional ones by using adaptive skills that are used in functional adaptive processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Some studies on the use of NASTRAN for nuclear power plant structural analysis and design

NASA Technical Reports Server (NTRS)

Setlur, A. V.; Valathur, M.

1973-01-01

Studies made on the use of NASTRAN for nuclear power plant analysis and design are presented. These studies indicate that NASTRAN could be effectively used for static, dynamic and special purpose problems encountered in the design of such plants. Normal mode capability of NASTRAN is extended through a post-processor program to handle seismic analysis. Static and dynamic substructuring is discussed. Extension of NASTRAN to include the needs in the civil engineering industry is discussed.

Insertion of coherence requests for debugging a multiprocessor

DOEpatents

Blumrich, Matthias A.; Salapura, Valentina

2010-02-23

A method and system are disclosed to insert coherence events in a multiprocessor computer system, and to present those coherence events to the processors of the multiprocessor computer system for analysis and debugging purposes. The coherence events are inserted in the computer system by adding one or more special insert registers. By writing into the insert registers, coherence events are inserted in the multiprocessor system as if they were generated by the normal coherence protocol. Once these coherence events are processed, the processing of coherence events can continue in the normal operation mode.

Derivation of equations of motion for multi-blade rotors employing coupled modes and including high twist capability

NASA Technical Reports Server (NTRS)

Sopher, R.

1975-01-01

The equations of motion are derived for a multiblade rotor. A high twist capability and coupled flatwise-edgewise assumed normal modes are employed instead of uncoupled flatwise - edgewise assumed normal models. The torsion mode is uncoupled. Support system models, consisting of complete helicopters in free flight, or grounded flexible supports, arbitrary rotor-induced inflow, and arbitrary vertical gust models are also used.

Plasma Modes

NASA Astrophysics Data System (ADS)

Dubin, D. H. E.

This chapter explores several aspects of the linear electrostatic normal modes of oscillation for a single-species non-neutral plasma in a Penning trap. Linearized fluid equations of motion are developed, assuming the plasma is cold but collisionless, which allow derivation of the cold plasma dielectric tensor and the electrostatic wave equation. Upper hybrid and magnetized plasma waves in an infinite uniform plasma are described. The effect of the plasma surface in a bounded plasma system is considered, and the properties of surface plasma waves are characterized. The normal modes of a cylindrical plasma column are discussed, and finally, modes of spheroidal plasmas, and finite temperature effects on the modes, are briefly described.

Inflow/Outflow Conditions for Unsteady Aerodynamics and Aeroacoustics in Nonuniform Flow

NASA Technical Reports Server (NTRS)

Atassi, Oliver V.; Grady, Joseph E. (Technical Monitor)

2003-01-01

The effect of a nonuniform mean flow on the normal modes; the inflow/outflow nonreflecting boundary conditions; and the sound power are studied. The normal modes in an annular duct are computed using a spectral method in combination with a shooting method. The swirl causes force imbalance which couples the acoustic and vortical modes. The acoustic modes are distinguished from the vortical modes by their large pressure and small vorticity content. The mean swirl also produces a Doppler shift in frequency. This results in more counter-spinning modes cut-on at a given frequency than modes spinning with the swirl. Nonreflecting boundary conditions are formulated using the normal mode solutions. The inflow/outflow boundary conditions are implemented in a linearized Euler scheme and validated by computing the propagation of acoustic and vortical waves in a duct for a variety of swirling mean flows. Numerical results show that the evolution of the vortical disturbances is sensitive to the inflow conditions and the details of the wake excitations. All three components of the wake velocity must be considered to correctly compute the wake evolution and the blade upwash. For high frequencies, the acoustic-vortical mode coupling is weak and a conservation equation for the acoustic energy can be derived. Sound power calculations show significant mean flow swirl effects, but mode interference effects are small.

WEBnm@ v2.0: Web server and services for comparing protein flexibility.

PubMed

Tiwari, Sandhya P; Fuglebakk, Edvin; Hollup, Siv M; Skjærven, Lars; Cragnolini, Tristan; Grindhaug, Svenn H; Tekle, Kidane M; Reuter, Nathalie

2014-12-30

Normal mode analysis (NMA) using elastic network models is a reliable and cost-effective computational method to characterise protein flexibility and by extension, their dynamics. Further insight into the dynamics-function relationship can be gained by comparing protein motions between protein homologs and functional classifications. This can be achieved by comparing normal modes obtained from sets of evolutionary related proteins. We have developed an automated tool for comparative NMA of a set of pre-aligned protein structures. The user can submit a sequence alignment in the FASTA format and the corresponding coordinate files in the Protein Data Bank (PDB) format. The computed normalised squared atomic fluctuations and atomic deformation energies of the submitted structures can be easily compared on graphs provided by the web user interface. The web server provides pairwise comparison of the dynamics of all proteins included in the submitted set using two measures: the Root Mean Squared Inner Product and the Bhattacharyya Coefficient. The Comparative Analysis has been implemented on our web server for NMA, WEBnm@, which also provides recently upgraded functionality for NMA of single protein structures. This includes new visualisations of protein motion, visualisation of inter-residue correlations and the analysis of conformational change using the overlap analysis. In addition, programmatic access to WEBnm@ is now available through a SOAP-based web service. Webnm@ is available at http://apps.cbu.uib.no/webnma . WEBnm@ v2.0 is an online tool offering unique capability for comparative NMA on multiple protein structures. Along with a convenient web interface, powerful computing resources, and several methods for mode analyses, WEBnm@ facilitates the assessment of protein flexibility within protein families and superfamilies. These analyses can give a good view of how the structures move and how the flexibility is conserved over the different structures.

Transverse mode analysis of optofluidic intracavity spectroscopy of canine hemangiosarcoma

NASA Astrophysics Data System (ADS)

Wang, Weina; Thamm, Douglas H.; Kisker, David W.; Lear, Kevin L.

2010-02-01

The label-free technique of optofluidic intracavity spectroscopy (OFIS) uses the optical transmission spectrum of a cell in a microfluidic optical resonator to distinguish cancerous and non-cancerous cells. Based on their distinctive characteristic transmission spectra, canine hemangiosarcoma (HSA) cancer cells and normal peripheral blood mononuclear cells (PBMCs) have been differentiated using the OFIS technique with high statistical significance (p<10- 6). 95% sensitivity and 98% specificity were achieved simultaneously. A cell lens model explains trends in the transverse mode pattern in the transmission spectra of HSA cells and allows extraction of cell focal length.

Turbulent transport measurements with a laser Doppler velocimeter

NASA Technical Reports Server (NTRS)

Edwards, R. V.; Angus, J. C.; Dunning, J. W., Jr.

1972-01-01

The power spectrum of phototube current from a laser Doppler velocimeter operating in the heterodyne mode has been computed. The spectrum is obtained in terms of the space time correlation function of the fluid. The spectral width and shape predicted by the theory are in agreement with experiment. For normal operating parameters the time average spectrum contains information only for times shorter than the Lagrangian integral time scale of the turbulence. To examine the long time behavior, one must use either extremely small scattering angles, much longer wavelength radiation or a different mode of signal analysis, e.g., FM detection.

On the mode-coupling treatment of collective density fluctuations for quantum liquids: para-hydrogen and normal liquid helium.

PubMed

Kletenik-Edelman, Orly; Reichman, David R; Rabani, Eran

2011-01-28

A novel quantum mode coupling theory combined with a kinetic approach is developed for the description of collective density fluctuations in quantum liquids characterized by Boltzmann statistics. Three mode-coupling approximations are presented and applied to study the dynamic response of para-hydrogen near the triple point and normal liquid helium above the λ-transition. The theory is compared with experimental results and to the exact imaginary time data generated by path integral Monte Carlo simulations. While for liquid para-hydrogen the combination of kinetic and quantum mode-coupling theory provides semi-quantitative results for both short and long time dynamics, it fails for normal liquid helium. A discussion of this failure based on the ideal gas limit is presented.

Sad and happy emotion discrimination in music by children with cochlear implants.

PubMed

Hopyan, Talar; Manno, Francis A M; Papsin, Blake C; Gordon, Karen A

2016-01-01

Children using cochlear implants (CIs) develop speech perception but have difficulty perceiving complex acoustic signals. Mode and tempo are the two components used to recognize emotion in music. Based on CI limitations, we hypothesized children using CIs would have impaired perception of mode cues relative to their normal hearing peers and would rely more heavily on tempo cues to distinguish happy from sad music. Study participants were children with 13 right CIs and 3 left CIs (M = 12.7, SD = 2.6 years) and 16 normal hearing peers. Participants judged 96 brief piano excerpts from the classical genre as happy or sad in a forced-choice task. Music was randomly presented with alterations of transposed mode, tempo, or both. When music was presented in original form, children using CIs discriminated between happy and sad music with accuracy well above chance levels (87.5%) but significantly below those with normal hearing (98%). The CI group primarily used tempo cues, whereas normal hearing children relied more on mode cues. Transposing both mode and tempo cues in the same musical excerpt obliterated cues to emotion for both groups. Children using CIs showed significantly slower response times across all conditions. Children using CIs use tempo cues to discriminate happy versus sad music reflecting a very different hearing strategy than their normal hearing peers. Slower reaction times by children using CIs indicate that they found the task more difficult and support the possibility that they require different strategies to process emotion in music than normal.

The Hall-induced stability of gravitating fluids

NASA Astrophysics Data System (ADS)

Karmakar, P. K.; Goutam, H. P.

2018-05-01

We analyze the stability behavior of low-density partially ionized self-gravitating magnetized unbounded dusty plasma fluid in the presence of the Hall diffusion effects (HDEs) in the non-ideal magnetohydrodynamic (MHD) equilibrium framework. The effects of inhomogeneous self-gravity are methodically included in the basic model tapestry. Application of the Fourier plane-wave perturbative treatment decouples the structuration representative parameters into a linear generalized dispersion relation (sextic) in a judicious mean-fluid approximation. The dispersion analysis shows that the normal mode, termed as the gravito-magneto-acoustic (GMA) mode, is drastically modified due to the HDEs. This mode is highly dispersive, and driven unstable by the Hall current resulting from the symmetry-breaking of electrons and ions relative to the magnetic field. The mode feature, which is derived from a modified induction with the positive Hall, is against the ideal MHD. It is further demonstrated that the HDEs play stabilizing roles by supporting the cloud against gravitational collapse. Provided that the HDEs are concurrently switched off, the collapse occurs on the global spatial scale due to enhanced inward accretion of the gravitating dust constituents. It is seen explicitly that the enhanced dust-charge leads to stabilizing effects. Besides, the Hall-induced fluctuations, as propagatory wave modes, exhibit both normal and anomalous dispersions. The reliability checkup of the entailed results as diverse corollaries and special cases are illustratively discussed in the panoptic light of the earlier paradigmatic predictions available in the literature.

Intrinsic hybrid modes in a corrugated conical horn

NASA Astrophysics Data System (ADS)

Dendane, A.; Arnold, J. M.

1988-08-01

Computational requirements for the generation of intrinsic modes in a nonseparable waveguide geometry requiring a full vector field description with anistropic impedance boundaries were derived. Good agreement is shown between computed and measured radiation patterns in copolar and crosspolar configurations. This agreement establishes that the intrinsic mode correctly accounts for the local normal mode conversion which takes place along the horn in a conventional mode coupling scheme, at least for cone semiangles up to 15 deg. The advantage of the intrinsic mode formulation over the conventional mode-coupling theory is that, to construct a single intrinsic mode throughout the horn, only one local normal mode field is required at each cross section, whereas mode conversion from the HE11 mode would require all the HE1n modes to be known at each cross section. The intrinsic mode accounts also for fields which would appear as backward modes in coupled-mode theory. A complete coupled-mode theory solution requires the inversion of a large matrix at each cross section, whereas the intrinsic mode can be constructed explicitly using a simple Fourier-like integral; the perturbation solution of Dragone (1977) is difficult to make rigorous.

Ice sheet altimetry

NASA Technical Reports Server (NTRS)

Brooks, R. L.

1981-01-01

Generalized surface slopes were computed for the Antarctic and Greenland ice sheets by differencing plotted contour levels and dividing them by the distance between the contours. It was observed that more than 90% of the ice sheets have surface slopes less than 1%. Seasat test mode-1 Seasat altimeter measurements over Greenland were analyzed by comparisons with collinear and intersecting normal mode Seasat altimeter passes. Over the ice sheet, the computed surface elevations from test mode-1 measurements were consistently lower by about 45 m and the AGC levels were down by approximately 6 dB. No test mode-1 data were acquired over Antarctica. It is concluded that analysis of the existing altimeter data base over the two ice sheets is crucial in designing a future improved altimeter tracking capability. It is recommended that additional waveform retracking be performed to characterize ice sheet topography as a function of geographic area and elevation.

[The investigation of formant on different artistic voice].

PubMed

Wang, Jianqun; Gao, Xia; Liu, Xiaozhou; Feng, Yulin; Shen, Xiaohui; Yu, Chenjie; Yang, Ye

2008-08-01

To explore the characteristic of formant-a very important parameter in the spectrogram of three types of artistic voice (western mode; Chinese mode; Beijing opera). We used MATLAB software to make the short-time Fourier transform and spectrogram analysis on the homeostasis vowel examples of the three types. The western mode had different representation "singer formant" (Fs) based on the voice part; the Chinese mode's notable features were that F1, F2, F3, were continuous and the energy of them changed softly; the Beijing opera had the common representation which was a very wide formant and there was soft transition between formants and various harmonic, besides it showed a similar component like the "Fs" (two formants connected normally). Different artistic voice showed their own characteristics of the formant parameter in the spectrogram, which had important value on the identification, objective evaluation and prediction.

Soft Vibrational Modes Predict Breaking Events during Force-Induced Protein Unfolding.

PubMed

Habibi, Mona; Plotkin, Steven S; Rottler, Jörg

2018-02-06

We investigate the correlation between soft vibrational modes and unfolding events in simulated force spectroscopy of proteins. Unfolding trajectories are obtained from molecular dynamics simulations of a Gō model of a monomer of a mutant of superoxide dismutase 1 protein containing all heavy atoms in the protein, and a normal mode analysis is performed based on the anisotropic network model. We show that a softness map constructed from the superposition of the amplitudes of localized soft modes correlates with unfolding events at different stages of the unfolding process. Soft residues are up to eight times more likely to undergo disruption of native structure than the average amino acid. The memory of the softness map is retained for extensions of up to several nanometers, but decorrelates more rapidly during force drops. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Spectral statistics of the acoustic stadium

NASA Astrophysics Data System (ADS)

Méndez-Sánchez, R. A.; Báez, G.; Leyvraz, F.; Seligman, T. H.

2014-01-01

We calculate the normal-mode frequencies and wave amplitudes of the two-dimensional acoustical stadium. We also obtain the statistical properties of the acoustical spectrum and show that they agree with the results given by random matrix theory. Some normal-mode wave amplitudes showing scarring are presented.

75 FR 62476 - Ultra-Wideband Transmission Systems

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-12

... would be obtained from measurements taken with the system operating in its normal operating mode. At the... with the transmitter operating continuously at a fundamental transmission frequency. 9. Subsequent to... systems, measured in their normal operating modes, is less than that of a UWB transmitter employing...

Statistical Analysis of Bursty Langmuir Waves, Alfvén and Whistler Waves, and Precipitating Electrons Seen by the CHARM II Nightside Sounding Rocket

NASA Astrophysics Data System (ADS)

Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.

2013-12-01

Bursty Langmuir waves have been interpreted as the result of the superposition of multiple Langmuir normal-mode waves, with the resultant modulation being the beat pattern between waves with e.g. 10 kHz frequency differences. The normal-mode waves could be generated either through wave-wave interactions with VLF waves, or through independent linear processes. The CHARM II sounding rocket was launched into a substorm at 9:49 UT on 15 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the Dartmouth High-Frequency Experiment (HFE), a receiver system which effectively yields continuous (100% duty cycle) E-field waveform measurements up to 5 MHz, as well as a number of charged particle detectors, including a wave-particle correlator. The payload also included a magnetometer and several low-frequency wave instruments. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, including several hundred discrete Langmuir-wave bursts. We show results of a statistical analysis of CHARM II data for the entire flight, comparing HFE data with the other payload instruments, specifically looking at timings and correlations between bursty Langmuir waves, Alfvén and whistler-mode waves, and electrons precipitating parallel to the magnetic field. Following a similar analysis on TRICE dayside sounding rocket data, we also calculate the fraction of correlated waves with VLF waves at appropriate frequencies to support the wave-wave interaction bursty Langmuir wave generation mechanism, and compare to results from CHARM II nightside data.

Observation of trapped-electron-mode microturbulence in reversed field pinch plasmas

NASA Astrophysics Data System (ADS)

Duff, J. R.; Williams, Z. R.; Brower, D. L.; Chapman, B. E.; Ding, W. X.; Pueschel, M. J.; Sarff, J. S.; Terry, P. W.

2018-01-01

Density fluctuations in the large-density-gradient region of improved confinement Madison Symmetric Torus reversed field pinch (RFP) plasmas exhibit multiple features that are characteristic of the trapped-electron mode (TEM). Core transport in conventional RFP plasmas is governed by magnetic stochasticity stemming from multiple long-wavelength tearing modes. Using inductive current profile control, these tearing modes are reduced, and global confinement is increased to that expected for comparable tokamak plasmas. Under these conditions, new short-wavelength fluctuations distinct from global tearing modes appear in the spectrum at a frequency of f ˜ 50 kHz, which have normalized perpendicular wavenumbers k⊥ρs≲ 0.2 and propagate in the electron diamagnetic drift direction. They exhibit a critical-gradient threshold, and the fluctuation amplitude increases with the local electron density gradient. These characteristics are consistent with predictions from gyrokinetic analysis using the Gene code, including increased TEM turbulence and transport from the interaction of remnant tearing magnetic fluctuations and zonal flow.

Even and odd normalized zero modes in random interacting Majorana models respecting the parity P and the time-reversal-symmetry T

NASA Astrophysics Data System (ADS)

Monthus, Cécile

2018-06-01

For random interacting Majorana models where the only symmetries are the parity P and the time-reversal-symmetry T, various approaches are compared to construct exact even and odd normalized zero modes Γ in finite size, i.e. Hermitian operators that commute with the Hamiltonian, that square to the identity, and that commute (even) or anticommute (odd) with the parity P. Even normalized zero-modes are well known under the name of ‘pseudo-spins’ in the field of many-body-localization or more precisely ‘local integrals of motion’ (LIOMs) in the many-body-localized-phase where the pseudo-spins happens to be spatially localized. Odd normalized zero-modes are popular under the name of ‘Majorana zero modes’ or ‘strong zero modes’. Explicit examples for small systems are described in detail. Applications to real-space renormalization procedures based on blocks containing an odd number of Majorana fermions are also discussed.

Raman spectral properties of squamous cell carcinoma of oral tissues and cells

NASA Astrophysics Data System (ADS)

Su, L.; Sun, Y. F.; Chen, Y.; Chen, P.; Shen, A. G.; Wang, X. H.; Jia, J.; Zhao, Y. F.; Zhou, X. D.; Hu, J. M.

2012-01-01

Early diagnosis is the key of the improved survival rates of oral cancer. Raman spectroscopy is sensitive to the early changes of molecular composition and structure that occur in benign lesion during carcinogenesis. In this study, in situ Raman analysis provided distinct spectra that can be used to discriminate between normal and malignant tissues, as well as normal and cancer cells. The biochemical variations between different groups were analyzed by the characteristic bands by comparing the normalized mean spectra. Spectral profiles of normal, malignant conditions show pronounced differences between one another, and multiple Raman markers associated with DNA and protein vibrational modes have been identified that exhibit excellent discrimination power for cancer sample identification. Statistical analyses of the Raman data and classification using principal component analysis (PCA) are shown to be effective for the Raman spectral diagnosis of oral mucosal diseases. The results indicate that the biomolecular differences between normal and malignant conditions are more obviously at the cellular level. This technique could provide a research foundation for the Raman spectral diagnosis of oral mucosal diseases.

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

Bukh, Boris; Lund, Steven M.

We present an analysis of envelope perturbations evolving in the limit of a fully space-charge depressed (zero emittance) beam in periodic, thin-lens focusing channels. Both periodic solenoidal and FODO quadrupole focusing channels are analyzed. The phase advance and growth rate of normal mode perturbations are analytically calculated as a function of the undepressed particle phase advance to characterize the evolution of envelope perturbations.

Space Shuttle main engine powerhead structural modeling, stress and fatigue life analysis. Volume 2: Dynamics of blades and nozzles SSME HPFTP and HPOTP

NASA Technical Reports Server (NTRS)

Hammett, J. C.; Hayes, C. H.; Price, J. M.; Robinson, J. K.; Teal, G. A.; Thomson, J. M.; Tilley, D. M.; Welch, C. T.

1983-01-01

Normal modes of the blades and nozzles of the HPFTP and HPOTP are defined and potential driving forces for the blades are identified. The computer models used in blade analyses are described, with results. Similar information is given for the nozzles.

Modeling Pulse Transmission in the Monterey Bay Using Parabolic Equation Methods

DTIC Science & Technology

1991-12-01

Collins 9-13 was chosen for this purpose due its energy conservation scheme , and its ability to efficiently incorporate higher order terms in its...pressure field generated by the PE model into normal modes. Additionally, this process provides increased physical understanding of mode coupling and...separation of variables (i.e. normal modes or fast field), as well as pure numerical schemes such as the parabolic equation methods, can be used. However, as

Normal co-ordinate analysis of 1, 8-dibromooctane

NASA Astrophysics Data System (ADS)

Singh, Devinder; Jaggi, Neena; Singh, Nafa

2010-02-01

The organic compound 1,8-dibromooctane (1,8-DBO) exists in liquid phase at ambient temperatures and has versatile synthetic applications. In its liquid phase 1,8-DBO has been expected to exist in four most probable conformations, with all its carbon atoms in the same plane, having symmetries C 2h , C i , C 2 and C 1 . In the present study a detailed vibrational analysis in terms of assignment of Fourier transform infrared (FT-IR) and Raman bands of this molecule using normal co-ordinate calculations has been done. A systematic set of symmetry co-ordinates has been constructed for this molecule and normal co-ordinate analysis is carried out using the computer program MOLVIB. The force-field transferred from already studied lower chain bromo-alkanes is subjected to refinement so as to fit the observed infrared and Raman frequencies with those of calculated ones. The potential energy distribution (PED) has also been calculated for each mode of vibration of the molecule for the assumed conformations.

A DMAP Program for the Selection of Accelerometer Locations in MSC/NASTRAN

NASA Technical Reports Server (NTRS)

Peck, Jeff; Torres, Isaias

2004-01-01

A new program for selecting sensor locations has been written in the DMAP (Direct Matrix Abstraction Program) language of MSC/NASTRAN. The program implements the method of Effective Independence for selecting sensor locations, and is executed within a single NASTRAN analysis as a "rigid format alter" to the normal modes solution sequence (SOL 103). The user of the program is able to choose among various analysis options using Case Control and Bulk Data entries. Algorithms tailored for the placement of both uni-axial and tri- axial accelerometers are available, as well as several options for including the model s mass distribution into the calculations. Target modes for the Effective Independence analysis are selected from the MSC/NASTRAN ASET modes calculated by the "SOL 103" solution sequence. The initial candidate sensor set is also under user control, and is selected from the ASET degrees of freedom. Analysis results are printed to the MSCINASTRAN output file (*.f06), and may include the current candidate sensors set, and their associated Effective Independence distribution, at user specified iteration intervals. At the conclusion of the analysis, the model is reduced to the final sensor set, and frequencies and orthogonality checks are printed. Example results are given for a pre-test analysis of NASA s five-segment solid rocket booster modal test.

On the identification of normal modes of oscillation from observations of the solar periphery

NASA Technical Reports Server (NTRS)

Gough, D. D.; Latour, J.

1984-01-01

The decomposition of solar oscillations into their constituent normal modes requires a knowledge of both the spatial and temporal variation of the perturbation to the Sun's surface. The task is especially difficult when only limited spatial information is available. Observations of the limb darkening function, for example, are probably sensitive to too large a number of modes to permit most of the modes to be identified in a power spectrum of measurements at only a few points on the limb, unless the results are combined with other data. A procedure was considered by which the contributions from quite small groups of modes to spatially well resolved data obtained at any instant can be extracted from the remaining modes. Combining these results with frequency information then permits the modes to be identified, at least if their frequencies are low enough to ensure that modes of high degree do not contribute substantially to the signal.

Computational modes and the Machenauer N.L.N.M.I. of the GLAS 4th order model. [NonLinear Normal Mode Initialization in numerical weather forecasting

NASA Technical Reports Server (NTRS)

Navon, I. M.; Bloom, S.; Takacs, L. L.

1985-01-01

An attempt was made to use the GLAS global 4th order shallow water equations to perform a Machenhauer nonlinear normal mode initialization (NLNMI) for the external vertical mode. A new algorithm was defined for identifying and filtering out computational modes which affect the convergence of the Machenhauer iterative procedure. The computational modes and zonal waves were linearly initialized and gravitational modes were nonlinearly initialized. The Machenhauer NLNMI was insensitive to the absence of high zonal wave numbers. The effects of the Machenhauer scheme were evaluated by performing 24 hr integrations with nondissipative and dissipative explicit time integration models. The NLNMI was found to be inferior to the Rasch (1984) pseudo-secant technique for obtaining convergence when the time scales of nonlinear forcing were much smaller than the time scales expected from the natural frequency of the mode.

Normal modes in an overmoded circular waveguide coated with lossy material

NASA Technical Reports Server (NTRS)

Lee, C. S.; Lee, S. W.; Chuang, S. L.

1985-01-01

The normal modes in an overmoded waveguide coated with a lossy material are analyzed, particularly for their attenuation properties as a function of coating material, layer thickness, and frequency. When the coating material is not too lossy, the low-order modes are highly attenuated even with a thin layer of coating. This coated guide serves as a mode suppressor of the low-order modes, which can be particularly useful for reducing the radar cross section (RCS) of a cavity structure such as a jet inlet. When the coating material is very lossy, low-order modes fall into two distinct groups: highly and lowly attenuated modes. However, as a/lambda (a = radius of the cylinder; lambda = the free-space wavelength) increases, the separation between these two groups becomes less distinctive. The attenuation constants of most of the low-order modes become small, and decrease as a function of lambda sup 2/a sup 3.

Nonlinear normal modes modal interactions and isolated resonance curves

DOE PAGES

Kuether, Robert J.; Renson, L.; Detroux, T.; ...

2015-05-21

The objective of the present study is to explore the connection between the nonlinear normal modes of an undamped and unforced nonlinear system and the isolated resonance curves that may appear in the damped response of the forced system. To this end, an energy balance technique is used to predict the amplitude of the harmonic forcing that is necessary to excite a specific nonlinear normal mode. A cantilever beam with a nonlinear spring at its tip serves to illustrate the developments. Furthermore, the practical implications of isolated resonance curves are also discussed by computing the beam response to sine sweepmore » excitations of increasing amplitudes.« less

Propagation of magnetostatic spin waves in an yttrium iron garnet film for out-of-plane magnetic fields

NASA Astrophysics Data System (ADS)

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan; Tsai, C. C.; Ketterson, John B.

2018-06-01

We have observed the propagation of spin waves across a thin yttrium iron garnet film on (1 1 1) gadolinium gallium garnet for magnetic fields inclined with respect to the film plane. Two principle planes were studied: that for H in the plane defined by the wave vector k and the plane normal, n, with limiting forms corresponding to the Backward Volume and Forward Volume modes, and that for H in the plane perpendicular to k, with limiting forms corresponding to the Damon-Eshbach and Forward Volume modes. By exciting the wave at one edge of the film and observing the field dependence of the phase of the received signal at the opposing edge we determined the frequency vs. wavevector relation, ω = ω (k), of various propagating modes in the film. Avoided crossings are observed in the Damon-Eshbach and Forward Volume regimes when the propagating mode intersects the higher, exchange split, volume modes, leading to an extinction of the propagating mode; analysis of the resulting behavior allows a determination of the exchange parameter. The experimental results are compared with theoretical simulations.

Approximate solution of the mode-mode coupling integral: Application to cytosine and its deuterated derivative.

PubMed

Rasheed, Tabish; Ahmad, Shabbir

2010-10-01

Ab initio Hartree-Fock (HF), density functional theory (DFT) and second-order Møller-Plesset (MP2) methods were used to perform harmonic and anharmonic calculations for the biomolecule cytosine and its deuterated derivative. The anharmonic vibrational spectra were computed using the vibrational self-consistent field (VSCF) and correlation-corrected vibrational self-consistent field (CC-VSCF) methods. Calculated anharmonic frequencies have been compared with the argon matrix spectra reported in literature. The results were analyzed with focus on the properties of anharmonic couplings between pair of modes. A simple and easy to use formula for calculation of mode-mode coupling magnitudes has been derived. The key element in present approach is the approximation that only interactions between pairs of normal modes have been taken into account, while interactions of triples or more are neglected. FTIR and Raman spectra of solid state cytosine have been recorded in the regions 400-4000 cm(-1) and 60-4000 cm(-1), respectively. Vibrational analysis and assignments are based on calculated potential energy distribution (PED) values. Copyright 2010 Elsevier B.V. All rights reserved.

[Ecological demonstration activity and eco-civilization construction mode: review and prospects].

PubMed

Mao, Hui-ping; He, Xuan; He, Jia; Niu, Dong-jie; Bao, Cun-kuan

2013-04-01

Ecological civilization is to normalize human development behaviors to harmonize the relationships between social and ecological development and eco-environment protection. In this paper, a comparative analysis was made on the ecological demonstration activities of ecological demonstration areas led by the Ministry of Environmental Protection, exemplar cities of national environmental protection, and ecological provinces, cities, and counties. It was considered that all the ecological demonstration activities had the problems of lacking pertinence of construction goals, disordered construction subjects, inefficient construction processes, and lacking continuous incentive mechanisms of assessment. In the meantime, through the analysis of the connotations of eco-civilization, the relationships between eco-civilization and eco-demonstration constructions were approached, and the eco-civilization construction mode was put forward in terms of construction goal, construction subject, and construction processes and assessment. The construction mode included the construction goal based on regional characteristics; the synergistic cooperation of construction subjects, the expanding ways of public participation, and the establishment of evaluation system for comprehensively measuring the 'actions and results'.

Improvements in Block-Krylov Ritz Vectors and the Boundary Flexibility Method of Component Synthesis

NASA Technical Reports Server (NTRS)

Carney, Kelly Scott

1997-01-01

A method of dynamic substructuring is presented which utilizes a set of static Ritz vectors as a replacement for normal eigenvectors in component mode synthesis. This set of Ritz vectors is generated in a recurrence relationship, proposed by Wilson, which has the form of a block-Krylov subspace. The initial seed to the recurrence algorithm is based upon the boundary flexibility vectors of the component. Improvements have been made in the formulation of the initial seed to the Krylov sequence, through the use of block-filtering. A method to shift the Krylov sequence to create Ritz vectors that will represent the dynamic behavior of the component at target frequencies, the target frequency being determined by the applied forcing functions, has been developed. A method to terminate the Krylov sequence has also been developed. Various orthonormalization schemes have been developed and evaluated, including the Cholesky/QR method. Several auxiliary theorems and proofs which illustrate issues in component mode synthesis and loss of orthogonality in the Krylov sequence have also been presented. The resulting methodology is applicable to both fixed and free- interface boundary components, and results in a general component model appropriate for any type of dynamic analysis. The accuracy is found to be comparable to that of component synthesis based upon normal modes, using fewer generalized coordinates. In addition, the block-Krylov recurrence algorithm is a series of static solutions and so requires significantly less computation than solving the normal eigenspace problem. The requirement for less vectors to form the component, coupled with the lower computational expense of calculating these Ritz vectors, combine to create a method more efficient than traditional component mode synthesis.

Interactions of the Salience Network and Its Subsystems with the Default-Mode and the Central-Executive Networks in Normal Aging and Mild Cognitive Impairment.

PubMed

Chand, Ganesh B; Wu, Junjie; Hajjar, Ihab; Qiu, Deqiang

2017-09-01

Previous functional magnetic resonance imaging (fMRI) investigations suggest that the intrinsically organized large-scale networks and the interaction between them might be crucial for cognitive activities. A triple network model, which consists of the default-mode network, salience network, and central-executive network, has been recently used to understand the connectivity patterns of the cognitively normal brains versus the brains with disorders. This model suggests that the salience network dynamically controls the default-mode and central-executive networks in healthy young individuals. However, the patterns of interactions have remained largely unknown in healthy aging or those with cognitive decline. In this study, we assess the patterns of interactions between the three networks using dynamical causal modeling in resting state fMRI data and compare them between subjects with normal cognition and mild cognitive impairment (MCI). In healthy elderly subjects, our analysis showed that the salience network, especially its dorsal subnetwork, modulates the interaction between the default-mode network and the central-executive network (Mann-Whitney U test; p < 0.05), which was consistent with the pattern of interaction reported in young adults. In contrast, this pattern of modulation by salience network was disrupted in MCI (p < 0.05). Furthermore, the degree of disruption in salience network control correlated significantly with lower overall cognitive performance measured by Montreal Cognitive Assessment (r = 0.295; p < 0.05). This study suggests that a disruption of the salience network control, especially the dorsal salience network, over other networks provides a neuronal basis for cognitive decline and may be a candidate neuroimaging biomarker of cognitive impairment.

Relativistic stellar stability: Preferred-frame effects

NASA Technical Reports Server (NTRS)

Ni, W.

1973-01-01

Possible preferred-frame effects on stellar stability were examined and no new instabilities were found. In particular, it is shown that: (1) Although terms linear in the preferred-frame velocity w (time-odd terms, analogous to viscosity and energy generation) change the shapes of the normal modes, their symmetry properties prevent them from changing the characteristic frequencies. Thus, no new vibrational or secular instabilities can occur. (2) Terms quadratic in w do not change either the shapes of the normal modes or the characteristic frequencies for radial pulsations. Thus, they have no influence on radial stability. (3) Terms quadratic in w do change both the normal modes and the characteristic frequencies of nonradial pulsations; but in the limit of a neutral mode these changes vanish. Hence, there is no modification of the criterion for convective stability, i.e., the standard Schwarzschild criterion remains valid.

Time series analysis of collective motions in proteins

NASA Astrophysics Data System (ADS)

Alakent, Burak; Doruker, Pemra; ćamurdan, Mehmet C.

2004-01-01

The dynamics of α-amylase inhibitor tendamistat around its native state is investigated using time series analysis of the principal components of the Cα atomic displacements obtained from molecular dynamics trajectories. Collective motion along a principal component is modeled as a homogeneous nonstationary process, which is the result of the damped oscillations in local minima superimposed on a random walk. The motion in local minima is described by a stationary autoregressive moving average model, consisting of the frequency, damping factor, moving average parameters and random shock terms. Frequencies for the first 50 principal components are found to be in the 3-25 cm-1 range, which are well correlated with the principal component indices and also with atomistic normal mode analysis results. Damping factors, though their correlation is less pronounced, decrease as principal component indices increase, indicating that low frequency motions are less affected by friction. The existence of a positive moving average parameter indicates that the stochastic force term is likely to disturb the mode in opposite directions for two successive sampling times, showing the modes tendency to stay close to minimum. All these four parameters affect the mean square fluctuations of a principal mode within a single minimum. The inter-minima transitions are described by a random walk model, which is driven by a random shock term considerably smaller than that for the intra-minimum motion. The principal modes are classified into three subspaces based on their dynamics: essential, semiconstrained, and constrained, at least in partial consistency with previous studies. The Gaussian-type distributions of the intermediate modes, called "semiconstrained" modes, are explained by asserting that this random walk behavior is not completely free but between energy barriers.

Guidance, navigation, and control subsystem for the EOS-AM spacecraft

NASA Technical Reports Server (NTRS)

Linder, David M.; Tolek, Joseph T.; Lombardo, John

1992-01-01

This paper presents the preliminary design of the Guidance, Navigation, and Control (GN&C) subsystem for the EOS-AM spacecraft and specifically focuses on the GN&C Normal Mode design. First, a brief description of the EOS-AM science mission, instruments, and system-level spacecraft design is provided. Next, an overview of the GN&C subsystem functional and performance requirements, hardware, and operating modes is presented. Then, the GN&C Normal Mode attitude determination, attitude control, and navigation systems are detailed. Finally, descriptions of the spacecraft's overall jitter performance and Safe Mode are provided.

Drought assessment using multi-sattelite remote sensing in Brazil

NASA Astrophysics Data System (ADS)

Rebello, V.; Getirana, A.; Rotunno Filho, O. C.; Lakshmi, V.

2016-12-01

In this study, we investigated long-term Terra-MODIS Normalized Difference Vegetation Index (NDVI) response to a recent drought period in Brazil's Southeast (SE) and Northeast (NE) regions between 2012 and 2015. An analysis of precipitation anomaly from 1979 to 2015 suggests a dry period over NE in 2012-2013 and SE in 2014-2015. Through EOF analysis it was possible to note that the first two modes account for 76% of variability and depict the vegetation seasonal cycle. Moreover, the time series of the respective modes show a deviation of NDVI in 2012 when both regions had negative precipitation anomaly. The other EOF modes show a negative trend from 2012 until 2015 mainly in northeastern Brazil in the semiarid region named Caatinga. In order to examine the influence of hydro-meterological variables on vegetation changes, the SVD technique was used to identify coupled patterns between NDVI and precipitation, soil moisture and evapotranspiration. SVD results showed that the highest correlations are achieved between NDVI and precipitation, 0.81 and 0.83, respectively in the first two modes. Although less correlated than precipitation, significant coupling between NDVI and evapotranspiration was found for the second and third modes, the correlation between their expanded coefficients was respectively 0.82 and 0.90.

Overcoming nanoscale friction barriers in transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Cammarata, Antonio; Polcar, Tomas

2017-08-01

We study the atomic contributions to the nanoscale friction in layered M X2 (M =Mo , W; X =S , Se, Te) transition metal dichalcogenides by combining ab initio techniques with group-theoretical analysis. Starting from stable atomic configurations, we propose a computational method, named normal-modes transition approximation (NMTA), to individuate possible sliding paths from only the analysis of the phonon modes of the stable geometry. The method provides a way to decompose the atomic displacements realizing the layer sliding in terms of phonon modes of the stable structure, so as to guide the selection and tuning of specific atomic motions promoting M X2 sheets gliding, and to adjust the corresponding energy barrier. The present results show that main contributions to the nanoscale friction are due to few low frequency phonon modes, corresponding to rigid shifts of M X2 layers. We also provide further evidences that a previously reported Ti-doped MoS2 phase is a promising candidate as new material with enhanced tribologic properties. The NMTA approach can be exploited to tune the energetic and the structural features of specific phonon modes, and, thanks to its general formulation, can also be applied to any solid state system, irrespective of the chemical composition and structural topology.

POD analysis of the instability mode of a low-speed streak in a laminar boundary layer

NASA Astrophysics Data System (ADS)

Deng, Si-Chao; Pan, Chong; Wang, Jin-Jun; Rinoshika, Akira

2017-12-01

The instability of one single low-speed streak in a zero-pressure-gradient laminar boundary layer is investigated experimentally via both hydrogen bubble visualization and planar particle image velocimetry (PIV) measurement. A single low-speed streak is generated and destabilized by the wake of an interference wire positioned normal to the wall and in the upstream. The downstream development of the streak includes secondary instability and self-reproduction process, which leads to the generation of two additional streaks appearing on either side of the primary one. A proper orthogonal decomposition (POD) analysis of PIV measured velocity field is used to identify the components of the streak instability in the POD mode space: for a sinuous/varicose type of POD mode, its basis functions present anti-symmetric/symmetric distributions about the streak centerline in the streamwise component, and the symmetry condition reverses in the spanwise component. It is further shown that sinuous mode dominates the turbulent kinematic energy (TKE) through the whole streak evolution process, the TKE content first increases along the streamwise direction to a saturation value and then decays slowly. In contrast, varicose mode exhibits a sustained growth of the TKE content, suggesting an increasing competition of varicose instability against sinuous instability.

Effect of rotation on Jeans instability of magnetized radiative quantum plasma

NASA Astrophysics Data System (ADS)

Joshi, H.; Pensia, R. K.

2017-03-01

The influence of rotation on the Jeans instability of homogeneous magnetized radiative quantum plasma is investigated. The basic equations of the problem are constructed and linearized by using the Quantum Magnetohydrodynamics (QMHD) model. The general dispersion relation is obtained by using the normal mode analysis technique, which is reduced for both the transverse and the longitudinal mode of propagations and further it is reduced for the axis of rotation parallel and perpendicular to the magnetic field. We found that the stabilizing effects of rotation are decreases for a strong magnetic field which is shown in the graphical representation. We also found that the quantum correction modified the condition of Jeans instability in both modes of propagation. The stabilizing effect of rotation is more increased in the presence of quantum correction.

Hall effect on magnetohydrodynamic instabilities at an elliptic magnetic stagnation line

NASA Astrophysics Data System (ADS)

Spies, Günther O.; Faghihi, Mustafa

1987-06-01

To answer the question whether the Hall effect removes the unphysical feature of ideal magnetohydrodynamics of predicting small wavelength kink instabilities at any elliptic magnetic stagnation line, a normal mode analysis is performed of the motion of an incompressible Hall fluid about cylindrical Z-pinch equilibria with circular cross sections. The eigenvalue loci in the complex frequency plane are derived for the equilibrium with constant current density. Every particular mode becomes stable as the Hall parameter exceeds a critical value. This value, however, depends on the mode such that it increases to infinity as the ideal growth rate decreases to zero, implying that there always remains an infinite number of slowly growing instabilities. Correspondingly, the stability criterion for equilibria with arbitrary current distributions is independent of the Hall parameter.

ECRH launching scenario in FFHR-d1

NASA Astrophysics Data System (ADS)

Yanagihara, Kota; Kubo, Shin; Shimozuma, Takashi; Yoshimura, Yasuo; Igami, Hiroe; Takahashi, Hiromi; Tsujimura, Tohru; Makino, Ryohhei

2016-10-01

ECRH is promising as a principal heating system in a prototype helical reactor FFHR-d1 where the heating power of 80 MW is required to bring the plasma parameter to break even condition. To generate the plasma and bring it to ignition condition in FFHR-d1, it is effective to heat the under/over-dense plasma with normal ECRH or Electron Bernstein Wave (EBW). Normal ECRH is well established but heating via EBW need sophisticated injection control. EBW can be excited via the O(ordinary)-X(extraordinary)-B(EBW) mode conversion process by launching the ordinary wave from the low field side to plasma cut-off layer with optimum injection angle, and the range of injection angle to get high OXB mode conversion rate is called OXB mode conversion window. Since the window position can change as the plasma parameter, it is necessary to optimize the injection angle so as to aim the window in response to the plasma parameters. Candidates of antenna positions are determined by optimum injection points on the plasma facing wall calculated by the injection angle. Given such picked up area, detailed analysis using ray-tracing calculations and engineering antenna design will be performed.

Streamwise Vorticity Generation in Laminar and Turbulent Jets

NASA Technical Reports Server (NTRS)

Demuren, Aodeji O.; Wilson, Robert V.

1999-01-01

Complex streamwise vorticity fields are observed in the evolution of non-circular jets. Generation mechanisms are investigated via Reynolds-averaged (RANS), large-eddy (LES) and direct numerical (DNS) simulations of laminar and turbulent rectangular jets. Complex vortex interactions are found in DNS of laminar jets, but axis-switching is observed only when a single instability mode is present in the incoming mixing layer. With several modes present, the structures are not coherent and no axis-switching occurs, RANS computations also produce no axis-switching. On the other hand, LES of high Reynolds number turbulent jets produce axis-switching even for cases with several instability modes in the mixing layer. Analysis of the source terms of the mean streamwise vorticity equation through post-processing of the instantaneous results shows that, complex interactions of gradients of the normal and shear Reynolds stresses are responsible for the generation of streamwise vorticity which leads to axis-switching. RANS computations confirm these results. k - epsilon turbulence model computations fail to reproduce the phenomenon, whereas algebraic Reynolds stress model (ASM) computations, in which the secondary normal and shear stresses are computed explicitly, succeeded in reproducing the phenomenon accurately.

Quantitative analysis of fetal facial morphology using 3D ultrasound and statistical shape modeling: a feasibility study.

PubMed

Dall'Asta, Andrea; Schievano, Silvia; Bruse, Jan L; Paramasivam, Gowrishankar; Kaihura, Christine Tita; Dunaway, David; Lees, Christoph C

2017-07-01

The antenatal detection of facial dysmorphism using 3-dimensional ultrasound may raise the suspicion of an underlying genetic condition but infrequently leads to a definitive antenatal diagnosis. Despite advances in array and noninvasive prenatal testing, not all genetic conditions can be ascertained from such testing. The aim of this study was to investigate the feasibility of quantitative assessment of fetal face features using prenatal 3-dimensional ultrasound volumes and statistical shape modeling. STUDY DESIGN: Thirteen normal and 7 abnormal stored 3-dimensional ultrasound fetal face volumes were analyzed, at a median gestation of 29 +4  weeks (25 +0 to 36 +1 ). The 20 3-dimensional surface meshes generated were aligned and served as input for a statistical shape model, which computed the mean 3-dimensional face shape and 3-dimensional shape variations using principal component analysis. Ten shape modes explained more than 90% of the total shape variability in the population. While the first mode accounted for overall size differences, the second highlighted shape feature changes from an overall proportionate toward a more asymmetric face shape with a wide prominent forehead and an undersized, posteriorly positioned chin. Analysis of the Mahalanobis distance in principal component analysis shape space suggested differences between normal and abnormal fetuses (median and interquartile range distance values, 7.31 ± 5.54 for the normal group vs 13.27 ± 9.82 for the abnormal group) (P = .056). This feasibility study demonstrates that objective characterization and quantification of fetal facial morphology is possible from 3-dimensional ultrasound. This technique has the potential to assist in utero diagnosis, particularly of rare conditions in which facial dysmorphology is a feature. Copyright © 2017 Elsevier Inc. All rights reserved.

Laser Doppler, velocimeter system for turbine stator cascade studies and analysis of statistical biasing errors

NASA Technical Reports Server (NTRS)

Seasholtz, R. G.

1977-01-01

A laser Doppler velocimeter (LDV) built for use in the Lewis Research Center's turbine stator cascade facilities is described. The signal processing and self contained data processing are based on a computing counter. A procedure is given for mode matching the laser to the probe volume. An analysis is presented of biasing errors that were observed in turbulent flow when the mean flow was not normal to the fringes.

Stability of strongly nonlinear normal modes

NASA Astrophysics Data System (ADS)

Recktenwald, Geoffrey; Rand, Richard

2007-10-01

It is shown that a transformation of time can allow the periodic solution of a strongly nonlinear oscillator to be written as a simple cosine function. This enables the stability of strongly nonlinear normal modes in multidegree of freedom systems to be investigated by standard procedures such as harmonic balance.

Angular motion equations for a satellite with hinged flexible solar panel

NASA Astrophysics Data System (ADS)

Ovchinnikov, M. Yu.; Tkachev, S. S.; Roldugin, D. S.; Nuralieva, A. B.; Mashtakov, Y. V.

2016-11-01

Non-linear mathematical model for the satellite with hinged flexible solar panel is presented. Normal modes of flexible elements are used for motion description. Motion equations are derived using virtual work principle. A comparison of normal modes calculation between finite element method and developed model is presented.

Normal Mode Analysis of Ambient-Noise Induced Free Oscillations of a Slender Medieval Masonry Tower in Bologna (Italy)

NASA Astrophysics Data System (ADS)

Morelli, A.; Azzara, R. M.; Cavaliere, A.; Zaccarelli, L.

2014-12-01

Analysis of the oscillations of buildings — either excited by earthquakes or by ambient noise — has become an effective tool to evaluate the response of such structures to strong ground motion, and hence to assess their seismic vulnerability. Response to small-amplitude ground motion may also provide crucial information on the elastic and anelastic properties of a structure — essential in the case of historical buildings — and constrain numerical full dynamic structural analyses. We report about an analysis carried out for a tall medieval monumental building in the urban center of the Norther Italian city of Bologna. Seismic monitoring, carried on for six months using field seismic instrumentation, has revealed the response to ambient noise, and has allowed to reconstruct, with high detail, the free oscillation modes of the tower. At 97 meters, the XII-century tower of the Asinelli is the tallest masonry building in Europe, and the most slender. We measured the fundamental, and several higher-order, flexural normal modes of oscillation, as well as the fundamental torsional mode. Asymmetry due to non-coincidence of centers of mass and of stiffness produces slightly different modal frequencies of oscillation in two orthogonal directions, consistently with dynamical modeling. Horizontal particle-motion polarization plots show the cyclic energy transfer between two degrees of freedom of the system. The Asinelli spectral signature can also be easily recognized in the motion recorded at the base of nearby Garisenda. We verify that there is correlation of spectral amplitudes with time of the day — in agreement with expected time-variance of anthropic disturbance —- but also with wind velocity and, intriguingly, with temperature variations inside the buidings. We are using these data to adjust the numerical dynamical models of the buildings, to examine time variations of behavior, and to identify the origin of anthropogenic sources of vibration in view of their possible mitigation.

Calculations of lattice vibrational mode lifetimes using Jazz: a Python wrapper for LAMMPS

NASA Astrophysics Data System (ADS)

Gao, Y.; Wang, H.; Daw, M. S.

2015-06-01

Jazz is a new python wrapper for LAMMPS [1], implemented to calculate the lifetimes of vibrational normal modes based on forces as calculated for any interatomic potential available in that package. The anharmonic character of the normal modes is analyzed via the Monte Carlo-based moments approximation as is described in Gao and Daw [2]. It is distributed as open-source software and can be downloaded from the website http://jazz.sourceforge.net/.

03pd0676

NASA Image and Video Library

2003-03-07

File name :DSC_0749.JPG File size :1.1MB(1174690Bytes) Date taken :2003/03/07 13:51:29 Image size :2000 x 1312 Resolution :300 x 300 dpi Number of bits :8bit/channel Protection attribute :Off Hide Attribute :Off Camera ID :N/A Camera :NIKON D1H Quality mode :FINE Metering mode :Matrix Exposure mode :Shutter priority Speed light :No Focal length :20 mm Shutter speed :1/500second Aperture :F11.0 Exposure compensation :0 EV White Balance :Auto Lens :20 mm F 2.8 Flash sync mode :N/A Exposure difference :0.0 EV Flexible program :No Sensitivity :ISO200 Sharpening :Normal Image Type :Color Color Mode :Mode II(Adobe RGB) Hue adjustment :3 Saturation Control :N/A Tone compensation :Normal Latitude(GPS) :N/A Longitude(GPS) :N/A Altitude(GPS) :N/A

Search for Long Period Solar Normal Modes in Ambient Seismic Noise

NASA Astrophysics Data System (ADS)

Caton, R.; Pavlis, G. L.

2016-12-01

We search for evidence of solar free oscillations (normal modes) in long period seismic data through multitaper spectral analysis of array stacks. This analysis is similar to that of Thomson & Vernon (2015), who used data from the most quiet single stations of the global seismic network. Our approach is to use stacks of large arrays of noisier stations to reduce noise. Arrays have the added advantage of permitting the use of nonparametic statistics (jackknife errors) to provide objective error estimates. We used data from the Transportable Array, the broadband borehole array at Pinyon Flat, and the 3D broadband array in Homestake Mine in Lead, SD. The Homestake Mine array has 15 STS-2 sensors deployed in the mine that are extremely quiet at long periods due to stable temperatures and stable piers anchored to hard rock. The length of time series used ranged from 50 days to 85 days. We processed the data by low-pass filtering with a corner frequency of 10 mHz, followed by an autoregressive prewhitening filter and median stack. We elected to use the median instead of the mean in order to get a more robust stack. We then used G. Prieto's mtspec library to compute multitaper spectrum estimates on the data. We produce delete-one jackknife error estimates of the uncertainty at each frequency by computing median stacks of all data with one station removed. The results from the TA data show tentative evidence for several lines between 290 μHz and 400 μHz, including a recurring line near 379 μHz. This 379 μHz line is near the Earth mode 0T2 and the solar mode 5g5, suggesting that 5g5 could be coupling into the Earth mode. Current results suggest more statistically significant lines may be present in Pinyon Flat data, but additional processing of the data is underway to confirm this observation.

Excited-state structure and isomerization dynamics of the retinal chromophore in rhodopsin from resonance Raman intensities.

PubMed Central

Loppnow, G R; Mathies, R A

1988-01-01

Resonance Raman excitation profiles have been measured for the bovine visual pigment rhodopsin using excitation wavelengths ranging from 457.9 to 647.1 nm. A complete Franck-Condon analysis of the absorption spectrum and resonance Raman excitation profiles has been performed using an excited-state, time-dependent wavepacket propagation technique. This has enabled us to determine the change in geometry upon electronic excitation of rhodopsin's 11-cis-retinal protonated Schiff base chromophore along 25 normal coordinates. Intense low-frequency Raman lines are observed at 98, 135, 249, 336, and 461 cm-1 whose intensities provide quantitative, mode-specific information about the excited-state torsional deformations that lead to isomerization. The dominant contribution to the width of the absorption band in rhodopsin results from Franck-Condon progressions in the 1,549 cm-1 ethylenic normal mode. The lack of vibronic structure in the absorption spectrum is shown to be caused by extensive progressions in low-frequency torsional modes and a large homogeneous linewidth (170 cm-1 half-width) together with thermal population of low-frequency modes and inhomogeneous site distribution effects. The resonance Raman cross-sections of rhodopsin are unusually weak because the excited-state wavepacket moves rapidly (approximately 35 fs) and permanently away from the Franck-Condon geometry along skeletal stretching and torsional coordinates. PMID:3416032

Fe-H/D stretching and bending modes in nuclear resonant vibrational, Raman and infrared spectroscopies: Comparisons of density functional theory and experiment

PubMed Central

Pelmenschikov, Vladimir; Guo, Yisong; Wang, Hongxin; Cramer, Stephen P.; Case, David A.

2010-01-01

Infrared, Raman, and nuclear resonant vibrational (NRVS) spectroscopies have been used to address the Fe-H bonding in trans-Fe(H)(CO) iron hydride compound, Fe(H)(CO)(dppe)2, dppe = 1,2-bis(diphenylphosphino)ethane. H and D isotopomers of the compound, with the selective substitution at the metal-coordinated hydrogen, have been considered in order to address the Fe-H/D stretching and bending modes. Experimental results are compared to the normal mode analysis by the density functional theory (DFT). The results are that (i) the IR spectrum does not clearly show Fe–H stretching or bending modes; (ii) Fe–H stretching modes are clear but weak in the Raman spectrum, and Fe–H bending modes are weak; (iii) NRVS 57Fe spectroscopy resolves Fe-H bending clearly, but Fe–H or Fe–D stretching is above its experimentally resolved frequency range. DFT caclulations (with no scaling of frequencies) show intensities and peak locations that allow unambigous correlations between observed and calculated features, with frequency errors generally less than 15 cm−1. Prospects for using these techniques to unravel vibrational modes of protein active sites are discussed. PMID:21322496

Investigation of fretting behaviour in pressure armour layers of flexible pipes

NASA Astrophysics Data System (ADS)

Don Rasika Perera, Solangarachchige

The incidence of fretting damage in the pressure armour wires of flexible pipes used in offshore oil explorations has been investigated. A novel experimental facility which is capable of simulating nub and valley contact conditions of interlocking wire winding with dynamic slip, representative of actual pipe loading, has been developed. The test set-up is equipped with a state of the art data acquisition system and a controller with transducers to measure and control the normal load, slip amplitude and friction force at the contact, in addition to the hoop stress in the wire. Tests were performed with selected loading and the fretted regions were examined using optical microscopy techniques. Results show that the magnitude of contact loading and the slip amplitude have a distinct influence on surface damage. Surface cracks originated from a fretting scar were observed at high contact loads in mixed slip sliding while surface damage predominantly due to wear was observed under gross slip. The position of surface cracks and the wear profile have been related to the contact pressure distribution. The evolution of friction force and surface damage under different slip and normal pressure conditions has been analysed. A fracture mechanics based numerical procedure has been developed to analyse the fretting damage behaviour. A severity parameter is proposed in order to ascertain whether the crack growth is in mode I or mode II cracking. The analysis show the influence of mode II cracking in the early stages of crack growth following which the crack deviates in the mode I direction making mode I the dominant crack propagation mechanism. The crack path determined by the numerical procedure correlates well with the experimental results. A numerical analysis was carried out for the fretting fatigue condition where a cyclic bulk stress superimposes with the friction force. The analysis correlates well with short crack growth behaviour. The analysis confirms that fretting is a significant factor that should be taken into account in design and operation of the pressure armour wires of flexible pipes at high contact pressure if the bulk cyclic load superimposes with the friction force. As predicted by the numerical procedure and further by experimental investigations, the surface cracks initiating on the wire in this condition are self arresting after propagating into a certain depth.

Dynamics of an [Fe4S4(SPh)4]2- cluster explored via IR, Raman, and nuclear resonance vibrational spectroscopy (NRVS)-analysis using 36S substitution, DFT calculations, and empirical force fields.

PubMed

Xiao, Yuming; Koutmos, Markos; Case, David A; Coucouvanis, Dimitri; Wang, Hongxin; Cramer, Stephen P

2006-05-14

We have used four vibrational spectroscopies--FT-IR, FT-Raman, resonance Raman, and 57Fe nuclear resonance vibrational spectroscopy (NRVS)--to study the normal modes of the Fe-S cluster in [(n-Bu)4N]2[Fe4S4(SPh)4]. This [Fe4S4(SR)4]2- complex serves as a model for the clusters in 4Fe ferredoxins and high-potential iron proteins (HiPIPs). The IR spectra exhibited differences above and below the 243 K phase transition. Significant shifts with 36S substitution into the bridging S positions were also observed. The NRVS results were in good agreement with the low temperature data from the conventional spectroscopies. The NRVS spectra were interpreted by normal mode analysis using optimized Urey-Bradley force fields (UBFF) as well as from DFT theory. For the UBFF calculations, the parameters were refined by comparing calculated and observed NRVS frequencies and intensities. The frequency shifts after 36S substitution were used as an additional constraint. A D 2d symmetry Fe4S4S'4 model could explain most of the observed frequencies, but a better match to the observed intensities was obtained when the ligand aromatic rings were included for a D 2d Fe4S4(SPh)4 model. The best results were obtained using the low temperature structure without symmetry constraints. In addition to stretching and bending vibrations, low frequency modes between approximately 50 and 100 cm(-1) were observed. These modes, which have not been seen before, are interpreted as twisting motions with opposing sides of the cube rotating in opposite directions. In contrast with a recent paper on a related Fe4S4 cluster, we find no need to assign a large fraction of the low frequency NRVS intensity to 'rotational lattice modes'. We also reassign the 430 cm(-1) band as primarily an elongation of the thiophenolate ring, with approximately 10% terminal Fe-S stretch character. This study illustrates the benefits of combining NRVS with conventional Raman and IR analysis for characterization of Fe-S centers. DFT theory is shown to provide remarkable agreement with the experimental NRVS data. These results provide a reference point for the analysis of more complex Fe-S clusters in proteins.

Washout of ⁸²Rb as a marker of impaired tissue integrity, obtained by list-mode cardiac PET/CT: relationship with perfusion/metabolism patterns of myocardial viability.

PubMed

Chien, David T; Bravo, Paco; Higuchi, Takahiro; Merrill, Jennifer; Bengel, Frank M

2011-08-01

Myocardial washout of the potassium analogue (82)Rb may indicate tissue impairment. Few studies have evaluated its usefulness for viability assessment, and controversial results were reported. We revisited this topic using list-mode positron emission tomography (PET)/CT. A total of 22 patients with chronic ischemic cardiomyopathy (ICM) and 11 control subjects with normal CT coronary angiogram were studied. Rest (82)Rb PET/CT studies were acquired in list mode and resampled to static, gated, and dynamic images. Using a 17-segment model, (82)Rb washout was determined by monoexponential fitting of myocardial time-activity curves. In ICM patients, (18)F-fluorodeoxyglucose (FDG) studies were obtained in the same session and segments were classified as normally perfused, mismatch, or matched defect. (82)Rb washout was minimal and homogeneous in control subjects. Normally perfused segments of ICM did not differ (p = 0.33). ICM patients had a left ventricular ejection fraction (LVEF) of 25 ± 12%, 25/353 mismatched, and 46/353 matched defect segments. (82)Rb washout was higher in hypoperfused vs normal segments (p < 0.05), but not different between mismatch and matched defect (p = 0.18). Intraindividual analysis in nine patients showing both FDG mismatch and matched defect confirmed absence of differences. Overall, segmental (82)Rb washout correlated inversely with (82)Rb uptake (r = -0.70; p < 0.05) and less well with FDG uptake (r = -0.31; p < 0.05). Using state-of-the-art PET/CT technology for myocardial viability assessment, (82)Rb washout does not distinguish between perfusion/metabolism patterns of hibernating myocardium and scar. Tissue integrity may be at least partially impaired in hibernation.

Numerical Study on Interdecadal Modulations of ENSO-related Spring Rainfall over South China by the Pacific Decadal Oscillation

NASA Astrophysics Data System (ADS)

MAO, J.; WU, X.

2017-12-01

The spatio-temporal variations of eastern China spring rainfall are identified via empirical orthogonal function (EOF) analysis of rain-gauge (gridded) precipitation datasets for the period 1958-2013 (1920-2013). The interannual variations of the first two leading EOF modes are linked with the El Niño-Southern Oscillation (ENSO), with this linkage being modulated by the Pacific Decadal Oscillation (PDO). The EOF1 mode, characterized by predominant rainfall anomalies from the Yangtze River to North China (YNC), is more likely associated with out-of-phase PDO-ENSO events [i.e., El Niño during cold PDO (EN_CPDO) and La Niña during warm PDO (LN_WPDO)]. The sea surface temperature anomaly (SSTA) distributions of EN_CPDO (LN_WPDO) events induce a significant anomalous anticyclone (cyclone) over the western North Pacific stretching northwards to the Korean Peninsula and southern Japan, resulting in anomalous southwesterlies (northeasterlies) prevailing over eastern China and above-normal (below-normal) rainfall over YNC. In contrast, EOF2 exhibits a dipole pattern with predominantly positive rainfall anomalies over southern China along with negative anomalies over YNC, which is more likely connected to in-phase PDO-ENSO events [i.e., El Niño during warm PDO (EN_WPDO) and La Niña during cold PDO (LN_CPDO)]. EN_WPDO (LN_CPDO) events force a southwest-northeast oriented dipole-like circulation pattern leading to significant anomalous southwesterlies (northeasterlies) and above-normal (below-normal) rainfall over southern China. Numerical experiments with the CAM5 model forced by the SSTA patterns of EN_WPDO and EN_CPDO events reproduce reasonably well the corresponding anomalous atmospheric circulation patterns and spring rainfall modes over eastern China, validating the related mechanisms.

Photoacoustic spectroscopy based investigatory approach to discriminate breast cancer from normal: a pilot study

NASA Astrophysics Data System (ADS)

Priya, Mallika; Rao, Bola Sadashiva Satish; Chandra, Subhash; Ray, Satadru; Mathew, Stanley; Datta, Anirbit; Nayak, Subramanya G.; Mahato, Krishna Kishore

2016-02-01

In spite of many efforts for early detection of breast cancer, there is still lack of technology for immediate implementation. In the present study, the potential photoacoustic spectroscopy was evaluated in discriminating breast cancer from normal, involving blood serum samples seeking early detection. Three photoacoustic spectra in time domain were recorded from each of 20 normal and 20 malignant samples at 281nm pulsed laser excitations and a total of 120 spectra were generated. The time domain spectra were then Fast Fourier Transformed into frequency domain and 116.5625 - 206.875 kHz region was selected for further analysis using a combinational approach of wavelet, PCA and logistic regression. Initially, wavelet analysis was performed on the FFT data and seven features (mean, median, area under the curve, variance, standard deviation, skewness and kurtosis) from each were extracted. PCA was then performed on the feature matrix (7x120) for discriminating malignant samples from the normal by plotting a decision boundary using logistic regression analysis. The unsupervised mode of classification used in the present study yielded specificity and sensitivity values of 100% in each respectively with a ROC - AUC value of 1. The results obtained have clearly demonstrated the capability of photoacoustic spectroscopy in discriminating cancer from the normal, suggesting its possible clinical implications.

Abnormal grain growth in AISI 304L stainless steel

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

Shirdel, M., E-mail: mshirdel1989@ut.ac.ir; Mirzadeh, H., E-mail: hmirzadeh@ut.ac.ir; Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran

2014-11-15

The microstructural evolution during abnormal grain growth (secondary recrystallization) in 304L stainless steel was studied in a wide range of annealing temperatures and times. At relatively low temperatures, the grain growth mode was identified as normal. However, at homologous temperatures between 0.65 (850 °C) and 0.7 (900 °C), the observed transition in grain growth mode from normal to abnormal, which was also evident from the bimodality in grain size distribution histograms, was detected to be caused by the dissolution/coarsening of carbides. The microstructural features such as dispersed carbides were characterized by optical metallography, X-ray diffraction, scanning electron microscopy, energy dispersivemore » X-ray analysis, and microhardness. Continued annealing to a long time led to the completion of secondary recrystallization and the subsequent reappearance of normal growth mode. Another instance of abnormal grain growth was observed at homologous temperatures higher than 0.8, which may be attributed to the grain boundary faceting/defaceting phenomenon. It was also found that when the size of abnormal grains reached a critical value, their size will not change too much and the grain growth behavior becomes practically stagnant. - Highlights: • Abnormal grain growth (secondary recrystallization) in AISI 304L stainless steel • Exaggerated grain growth due to dissolution/coarsening of carbides • The enrichment of carbide particles by titanium • Abnormal grain growth due to grain boundary faceting at very high temperatures • The stagnancy of abnormal grain growth by annealing beyond a critical time.« less

Poetry and Scientific Exposition: An Analysis of Two Forms of Symbolic Representation

ERIC Educational Resources Information Center

Cooper, Monica Wengrowicz

2002-01-01

Art and science are generally thought to be two different forms of human activity. When speaking of "arts," one normally uses the term to encompass diverse types of art such as painting, poetry, and music, even though the modes of symbolization in the different arts are based on different characters such as notes, lines, and words. Science,…

Identification of natural frequencies and modal damping ratios of aerospace structures from response data

NASA Technical Reports Server (NTRS)

Michalopoulos, C. D.

1976-01-01

An analysis of one and multidegree of freedom systems with classical damping is presented. Definition and minimization of error functions for each system are discussed. Systems with classical and nonclassical normal modes are studied, and results for first order perturbation are given. An alternative method of matching power spectral densities is provided, and numerical results are reviewed.

Bayesian Analysis of Item Response Curves. Research Report 84-1. Mathematical Sciences Technical Report No. 132.

ERIC Educational Resources Information Center

Tsutakawa, Robert K.; Lin, Hsin Ying

Item response curves for a set of binary responses are studied from a Bayesian viewpoint of estimating the item parameters. For the two-parameter logistic model with normally distributed ability, restricted bivariate beta priors are used to illustrate the computation of the posterior mode via the EM algorithm. The procedure is illustrated by data…

A static acoustic signature system for the analysis of dynamic flight information

NASA Technical Reports Server (NTRS)

Ramer, D. J.

1978-01-01

The Army family of helicopters was analyzed to measure the polar octave band acoustic signature in various modes of flight. A static array of calibrated microphones was used to simultaneously acquire the signature and differential times required to mathematically position the aircraft in space. The signature was then reconstructed, mathematically normalized to a fixed radius around the aircraft.

Extensions to the instantaneous normal mode analysis of cluster dynamics: Diffusion constants and the role of rotations in clusters

NASA Astrophysics Data System (ADS)

Adams, John E.; Stratt, Richard M.

1990-08-01

For the instantaneous normal mode analysis method to be generally useful in studying the dynamics of clusters of arbitrary size, it ought to yield values of atomic self-diffusion constants which agree with those derived directly from molecular dynamics calculations. The present study proposes that such agreement indeed can be obtained if a sufficiently sophisticated formalism for computing the diffusion constant is adopted, such as the one suggested by Madan, Keyes, and Seeley [J. Chem. Phys. 92, 7565 (1990)]. In order to implement this particular formalism, however, we have found it necessary to pay particular attention to the removal from the computed spectra of spurious rotational contributions. The utility of the formalism is demonstrated via a study of small argon clusters, for which numerous results generated using other approaches are available. We find the same temperature dependence of the Ar13 self-diffusion constant that Beck and Marchioro [J. Chem. Phys. 93, 1347 (1990)] do from their direct calculation of the velocity autocorrelation function: The diffusion constant rises quickly from zero to a liquid-like value as the cluster goes through (the finite-size equivalent of) the melting transition.

Time-frequency analysis to a particular type of scattering problems involving metallic-polymer tubing structures.

PubMed

Elhanaoui, Abdelkader; Aassif, Elhoucein; Maze, Gérard; Décultot, Dominique

2018-01-01

In this paper, recent studies of backscattered acoustic signals in thinner steel-polymer tubing structures have been presented. Reassigned smoothed pseudo Wigner-Ville (rspWV) analysis has been adopted in order to diminish the cross-term effect, and achieve high resolution spectral. Vibration modes, which are associated to the resonances of circumferential waves, have been determined by using the modal isolation plan representation. At normalized frequencies below 140, an appreciable influence from the polymer coating thickness on the A 0 + and S 0 modes has been noticed. Furthermore, the trajectory of the A 0 - wave has been modified in the normalized frequency band 40-42. Group velocity curves of the A 0 - wave have, then, been graphically illustrated. The findings have shown a particular curvature change at reduced frequency 41 in the case of an immersed two-layer tube in water. Studies of acoustic backscattering involving steel-polymer tubing structures have confirmed the significant coupling of A 0 + and S 0 waves. Besides, the disappearance of the A 0 + resonance trajectory has been observed; which is a very important phenomenon to understand. Copyright © 2017 Elsevier B.V. All rights reserved.

Lattice QCD analysis for relation between quark confinement and chiral symmetry breaking

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

Doi, Takahiro M.; Suganuma, Hideo; Iritani, Takumi

2016-01-22

The Polyakov loop and the Dirac modes are connected via a simple analytical relation on the temporally odd-number lattice, where the temporal lattice size is odd with the normal (nontwisted) periodic boundary condition. Using this relation, we investigate the relation between quark confinement and chiral symmetry breaking in QCD. In this paper, we discuss the properties of this analytical relation and numerically investigate each Dirac-mode contribution to the Polyakov loop in both confinement and deconfinement phases at the quenched level. This relation indicates that low-lying Dirac modes have little contribution to the Polyakov loop, and we numerically confirmed this fact.more » From our analysis, it is suggested that there is no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD. Also, in the confinement phase, we numerically find that there is a new “positive/negative symmetry” in the Dirac-mode matrix elements of link-variable operator which appear in the relation and the Polyakov loop becomes zero because of this symmetry. In the deconfinement phase, this symmetry is broken and the Polyakov loop is non-zero.« less

The Amount and Preferred Orientation of Simple-shear in a Deformation Tensor: Implications for Detecting Shear Zones and Faults with GPS

NASA Astrophysics Data System (ADS)

Johnson, A. M.; Griffiths, J. H.

2007-05-01

At the 2005 Fall Meeting of the American Geophysical Union, Griffiths and Johnson [2005] introduced a method of extracting from the deformation-gradient (and velocity-gradient) tensor the amount and preferred orientation of simple-shear associated with 2-D shear zones and faults. Noting the 2-D is important because the shear zones and faults in Griffiths and Johnson [2005] were assumed non-dilatant and infinitely long, ignoring the scissors- like action along strike associated with shear zones and faults of finite length. Because shear zones and faults can dilate (and contract) normal to their walls and can have a scissors-like action associated with twisting about an axis normal to their walls, the more general method of detecting simple-shear is introduced and called MODES "method of detecting simple-shear." MODES can thus extract from the deformation-gradient (and velocity- gradient) tensor the amount and preferred orientation of simple-shear associated with 3-D shear zones and faults near or far from the Earth's surface, providing improvements and extensions to existing analytical methods used in active tectonics studies, especially strain analysis and dislocation theory. The derivation of MODES is based on one definition and two assumptions: by definition, simple-shear deformation becomes localized in some way; by assumption, the twirl within the deformation-gradient (or the spin within the velocity-gradient) is due to a combination of simple-shear and twist, and coupled with the simple- shear and twist is a dilatation of the walls of shear zones and faults. The preferred orientation is thus the orientation of the plane containing the simple-shear and satisfying the mechanical and kinematical boundary conditions. Results from a MODES analysis are illustrated by means of a three-dimensional diagram, the cricket- ball, which is reminiscent of the seismologist's "beach ball." In this poster, we present the underlying theory of MODES and illustrate how it works by analyzing the three- dimensional displacements measured with the Global Positioning System across the 1999 Chi-Chi earthquake ground rupture in Taiwan. In contrast to the deformation zone in the upper several meters of the ground below the surface detected by Yu et al. [2001], MODES determines the orientation and direction of shift of a shear zone representing the earthquake fault within the upper several hundred or thousand meters of ground below the surface. Thus, one value of the MODES analysis in this case is to provide boundary conditions for dislocation solutions for the subsurface shape of the main rupture during the earthquake.

An Aeroelastic Analysis of a Thin Flexible Membrane

NASA Technical Reports Server (NTRS)

Scott, Robert C.; Bartels, Robert E.; Kandil, Osama A.

2007-01-01

Studies have shown that significant vehicle mass and cost savings are possible with the use of ballutes for aero-capture. Through NASA's In-Space Propulsion program, a preliminary examination of ballute sensitivity to geometry and Reynolds number was conducted, and a single-pass coupling between an aero code and a finite element solver was used to assess the static aeroelastic effects. There remain, however, a variety of open questions regarding the dynamic aeroelastic stability of membrane structures for aero-capture, with the primary challenge being the prediction of the membrane flutter onset. The purpose of this paper is to describe and begin addressing these issues. The paper includes a review of the literature associated with the structural analysis of membranes and membrane utter. Flow/structure analysis coupling and hypersonic flow solver options are also discussed. An approach is proposed for tackling this problem that starts with a relatively simple geometry and develops and evaluates analysis methods and procedures. This preliminary study considers a computationally manageable 2-dimensional problem. The membrane structural models used in the paper include a nonlinear finite-difference model for static and dynamic analysis and a NASTRAN finite element membrane model for nonlinear static and linear normal modes analysis. Both structural models are coupled with a structured compressible flow solver for static aeroelastic analysis. For dynamic aeroelastic analyses, the NASTRAN normal modes are used in the structured compressible flow solver and 3rd order piston theories were used with the finite difference membrane model to simulate utter onset. Results from the various static and dynamic aeroelastic analyses are compared.

Relationships between nonlinear normal modes and response to random inputs

NASA Astrophysics Data System (ADS)

Schoneman, Joseph D.; Allen, Matthew S.; Kuether, Robert J.

2017-02-01

The ability to model nonlinear structures subject to random excitation is of key importance in designing hypersonic aircraft and other advanced aerospace vehicles. When a structure is linear, superposition can be used to construct its response to a known spectrum in terms of its linear modes. Superposition does not hold for a nonlinear system, but several works have shown that a system's dynamics can still be understood qualitatively in terms of its nonlinear normal modes (NNMs). This work investigates the connection between a structure's undamped nonlinear normal modes and the spectrum of its response to high amplitude random forcing. Two examples are investigated: a spring-mass system and a clamped-clamped beam modeled within a geometrically nonlinear finite element package. In both cases, an intimate connection is observed between the smeared peaks in the response spectrum and the frequency-energy dependence of the nonlinear normal modes. In order to understand the role of coupling between the underlying linear modes, reduced order models with and without modal coupling terms are used to separate the effect of each NNM's backbone from the nonlinear couplings that give rise to internal resonances. In the cases shown here, uncoupled, single-degree-of-freedom nonlinear models are found to predict major features in the response with reasonable accuracy; a highly inexpensive approximation such as this could be useful in design and optimization studies. More importantly, the results show that a reduced order model can be expected to give accurate results only if it is also capable of accurately predicting the frequency-energy dependence of the nonlinear modes that are excited.

Quasi-normal modes of extremal BTZ black holes in TMG

NASA Astrophysics Data System (ADS)

Afshar, Hamid R.; Alishahiha, Mohsen; Mosaffa, Amir E.

2010-08-01

We study the spectrum of tensor perturbations on extremal BTZ black holes in topologically massive gravity for arbitrary values of the coefficient of the Chern-Simons term, μ. Imposing proper boundary conditions at the boundary of the space and at the horizon, we find that the spectrum contains quasi-normal modes.

Mode detuning in systems of weakly coupled oscillators

NASA Astrophysics Data System (ADS)

Spencer, Ross L.; Robertson, Richard D.

2001-11-01

A system of weakly magnetically coupled oscillating blades is studied experimentally, computationally, and theoretically. It is found that when the uncoupled natural frequencies of the blades are nearly equal, the normal modes produced by the coupling are almost impossible to find experimentally if the random variation level in the system parameters is on the order of (or larger than) the relative differences between mode frequencies. But if the uncoupled natural frequencies are made to vary (detuned) in a smooth way such that the total relative spread in natural frequency exceeds the random variations, normal modes are rather easy to find. And if the detuned uncoupled frequencies of the system are parabolically distributed, the modes are found to be shaped like Hermite functions.

Shear-coupled grain-boundary migration dependence on normal strain/stress

NASA Astrophysics Data System (ADS)

Combe, N.; Mompiou, F.; Legros, M.

2017-08-01

In specific conditions, grain-boundary (GB) migration occurs in polycrystalline materials as an alternative vector of plasticity compared to the usual dislocation activity. The shear-coupled GB migration, the expected most efficient GB based mechanism, couples the GB motion to an applied shear stress. Stresses on GB in polycrystalline materials seldom have, however, a unique pure shear component. This work investigates the influence of a normal strain on the shear coupled migration of a Σ 13 (320 )[001 ] GB in a copper bicrystal using atomistic simulations. We show that the yield shear stress inducing the GB migration strongly depends on the applied normal stress. Beyond, the application of a normal stress on this GB qualitatively modifies the GB migration: while the Σ 13 (320 )[001 ] GB shear couples following the 〈110 〉 migration mode without normal stress, we report the observation of the 〈010 〉 mode under a sufficiently high tensile normal stress. Using the nudge elastic band method, we uncover the atomistic mechanism of this 〈010 〉 migration mode and energetically characterize it.

Effect of fine dust particles and finite electron inertia of rotating magnetized plasma

NASA Astrophysics Data System (ADS)

Kumar, V.; Sutar, D. L.; Pensia, R. K.; Sharma, S.

2018-05-01

A theoretical investigation has been made of the effect of fine dust particles, viscosity and electron inertia on Jeans instability in a self-gravitating magnetized rotating plasma. The MHD model is used to formulate the problem in which a general dispersion relation. A general dispersion relation is obtained from the linearized perturbation equations using the normal mode analysis method. The analytical expressions of the growth rate of Jeans instability are obtained for the longitudinal and transverse mode of propagation. The present result shows that the Jeans criterion of instability is modified due to the presence of viscosity, rotation, and magnetic field.

Formation and characterization of perpendicular mode Si ripples by glancing angle O{sub 2}{sup +} sputtering at room temperature

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

Mollick, S. A.; Ghose, D.

Off-normal low energy ion beam sputtering of solid surfaces often leads to morphological instabilities resulting in the spontaneous formation of ripple structures in nanometer length scales. In the case of Si surfaces at ambient temperature, ripple formation is found to take place normally at lower incident angles with the wave vector parallel to the ion beam direction. The absence of ripple pattern on Si surface at larger angles is due to the dominance of ion beam polishing effect. We have shown that a gentle chemical roughening of the starting surface morphology can initiate ripple pattern under grazing incidence ion beammore » sputtering (theta>64 deg. with respect to the surface normal), where the ripple wave vector is perpendicular to the ion beam direction. The characteristics of the perpendicular mode ripples are studied as a function of pristine surface roughness (2-30 nm) and projectile fluence (5x10{sup 16}-1.5x10{sup 18} O atoms cm{sup -2}). The quality of the morphological structure is assessed from the analysis of ion induced topological defects.« less

Higher order mode couplers for normal conducting DORIS 5-cell cavities

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

Dewersteg, B.; Seesselberg, E.; Zolfaghari, A.

1985-10-01

The beam intensity of the DORIS e -e storage ring is limited to about 100 mA average circulation current as a result of instabilities driven by higher order rf cavity modes. Thus an investigation has been made of the higher order mode impedances of the DORIS rf accelerator cavities. These cavities are the same as the normally conducting inductively coupled 500 MHz 5-cell structures used in PETRA. The results of the investigation were applied for the construction of inductive and capacitive attenuation antennae corresponding to specific mode spectra and mode impedances. The antennae must fit into the existing 35 mmmore » pick up flanges of the cavities and in spite of these size and position limitations they must be efficient in reducing the shunt impedances of the dangerous modes.« less

Kelvin waves: a comparison study between SABER and normal mode analysis of ECMWF data

NASA Astrophysics Data System (ADS)

Blaauw, Marten; Garcia, Rolando; Zagar, Nedjeljka; Tribbia, Joe

2014-05-01

Equatorial Kelvin waves spectra are sensitive to the multi-scale variability of their source of tropical convective forcing. Moreover, Kelvin wave spectra are modified upward by changes in the background winds and stability. Recent high resolution data from observations as well as analyses are capable of resolving the slower Kelvin waves with shorter vertical wavelength near the tropical tropopause. In this presentation, results from a quantitive comparison study of stratospheric Kelvin waves in satellite data (SABER) and analysis data from the ECMWF operational archive will be shown. Temperature data from SABER is extracted over a six year period (2007-2012) with an effective vertical resolution of 2 km. Spectral power of stratospheric Kelvin waves in SABER data is isolated by selecting symmetric and eastward spectral components in the 8-20 days range. Global data from ECMWF operational analysis is extracted for the same six years on 91 model levels (top level at 0.01 hPa) and 25 km horizontal resolution. Using three-dimensional orthogonal normal-mode expansions, the input mass and wind data from ECMWF is projected onto balanced rotational modes and unbalanced inertia-gravity modes, including spectral data for pure Kelvin waves. The results show good agreement between Kelvin waves in SABER and ECMWF analyses data for: (i) the frequency shift of Kelvin wave variance with height and (ii) vertical wavelengths. Variability with respect to QBO will also be discussed. In a previous study, discrepancies in the upper stratosphere were found to be 60% and are found here to be 10% (8-20 day averaged value), which can be explained by the better stratosphere representation in the 91 model level version of the ECMWF operational model. New discrepancies in Kelvin wave variance are found in the lower stratosphere at 20 km. Averaged spectral power over the 8-20 day range is found to be 35% higher in ECMWF compared to SABER data. We compared results at 20 km with additional satellite data from HIRDLS (1 km eff. resolution) and conclude preliminary that SABER data does not represent the shortest 20 day Kelvin waves as well as HIRDLS and ECMWF operational analysis.

Conjugate gradient filtering of instantaneous normal modes, saddles on the energy landscape, and diffusion in liquids.

PubMed

Chowdhary, J; Keyes, T

2002-02-01

Instantaneous normal modes (INM's) are calculated during a conjugate-gradient (CG) descent of the potential energy landscape, starting from an equilibrium configuration of a liquid or crystal. A small number (approximately equal to 4) of CG steps removes all the Im-omega modes in the crystal and leaves the liquid with diffusive Im-omega which accurately represent the self-diffusion constant D. Conjugate gradient filtering appears to be a promising method, applicable to any system, of obtaining diffusive modes and facilitating INM theory of D. The relation of the CG-step dependent INM quantities to the landscape and its saddles is discussed.

Polariton condensation with saturable molecules dressed by vibrational modes

DOE PAGES

Cwik, Justyna A.; Reja, Sahinur; Littlewood, Peter B.; ...

2014-02-01

Here, polaritons, mixed light-matter quasiparticles, undergo a transition to a condensed, macroscopically coherent state at low temperatures or high densities. Recent experiments show that coupling light to organic molecules inside a microcavity allows condensation at room temperature. The molecules act as saturable absorbers with transitions dressed by molecular vibrational modes. Motivated by this, we calculate the phase diagram and spectrum of a modified Tavis-Cummings model, describing vibrationally dressed two-level systems, coupled to a cavity mode. Coupling to vibrational modes can induce re-entrance, i.e. a normal-condensed-normal sequence with decreasing temperature and can drive the transition first-order.

Signature of nonadiabatic coupling in excited-state vibrational modes.

PubMed

Soler, Miguel A; Nelson, Tammie; Roitberg, Adrian E; Tretiak, Sergei; Fernandez-Alberti, Sebastian

2014-11-13

Using analytical excited-state gradients, vibrational normal modes have been calculated at the minimum of the electronic excited-state potential energy surfaces for a set of extended conjugated molecules with different coupling between them. Molecular model systems composed of units of polyphenylene ethynylene (PPE), polyphenylenevinylene (PPV), and naphthacene/pentacene (NP) have been considered. In all cases except the NP model, the influence of the nonadiabatic coupling on the excited-state equilibrium normal modes is revealed as a unique highest frequency adiabatic vibrational mode that overlaps with the coupling vector. This feature is removed by using a locally diabatic representation in which the effect of NA interaction is removed. Comparison of the original adiabatic modes with a set of vibrational modes computed in the locally diabatic representation demonstrates that the effect of nonadiabaticity is confined to only a few modes. This suggests that the nonadiabatic character of a molecular system may be detected spectroscopically by identifying these unique state-specific high frequency vibrational modes.

On the identification of normal modes of oscillation from observations of the solar periphery

NASA Technical Reports Server (NTRS)

Gough, D. O.; Latour, J.

1984-01-01

The decomposition of solar oscillations into their constituent normal modes requires a knowledge of both the spatial and temporal variation of the perturbation to the sun's surface. The task can be especially difficult when only limited spatial information is available. Observations of the limb-darkening function, for example, are probably sensitive to too large a number of modes to permit most of the modes to be identified in a power spectrum of measurements at only a few points on the limb, unless the results are combined with other data. In this paper a procedure is considered by which the contributions from quite small groups of modes to spatially well resolved data obtained at any instant can be extracted from the remaining modes. Combining these results with frequency information then permits the modes to be identified, at least if their frequencies are low enough to ensure that modes of high degree do not contribute substantially to the signal.

The stability of the three transmembrane and the four transmembrane human vitamin K epoxide reductase models

NASA Astrophysics Data System (ADS)

Wu, Sangwook

2016-04-01

The three transmembrane and the four transmembrane helix models are suggested for human vitamin K epoxide reductase (VKOR). In this study, we investigate the stability of the human three transmembrane/four transmembrane VKOR models by employing a coarse-grained normal mode analysis and molecular dynamics simulation. Based on the analysis of the mobility of each transmembrane domain, we suggest that the three transmembrane human VKOR model is more stable than the four transmembrane human VKOR model.

Development and Integration of Control System Models

NASA Technical Reports Server (NTRS)

Kim, Young K.

1998-01-01

The computer simulation tool, TREETOPS, has been upgraded and used at NASA/MSFC to model various complicated mechanical systems and to perform their dynamics and control analysis with pointing control systems. A TREETOPS model of Advanced X-ray Astrophysics Facility - Imaging (AXAF-1) dynamics and control system was developed to evaluate the AXAF-I pointing performance for Normal Pointing Mode. An optical model of Shooting Star Experiment (SSE) was also developed and its optical performance analysis was done using the MACOS software.

Multi-disciplinary optimization of aeroservoelastic systems

NASA Technical Reports Server (NTRS)

Karpel, Mordechay

1991-01-01

New methods were developed for efficient aeroservoelastic analysis and optimization. The main target was to develop a method for investigating large structural variations using a single set of modal coordinates. This task was accomplished by basing the structural modal coordinates on normal modes calculated with a set of fictitious masses loading the locations of anticipated structural changes. The following subject areas are covered: (1) modal coordinates for aeroelastic analysis with large local structural variations; and (2) time simulation of flutter with large stiffness changes.

Principal component and normal mode analysis of proteins; a quantitative comparison using the GroEL subunit.

PubMed

Skjaerven, Lars; Martinez, Aurora; Reuter, Nathalie

2011-01-01

Principal component analysis (PCA) and normal mode analysis (NMA) have emerged as two invaluable tools for studying conformational changes in proteins. To compare these approaches for studying protein dynamics, we have used a subunit of the GroEL chaperone, whose dynamics is well characterized. We first show that both PCA on trajectories from molecular dynamics (MD) simulations and NMA reveal a general dynamical behavior in agreement with what has previously been described for GroEL. We thus compare the reproducibility of PCA on independent MD runs and subsequently investigate the influence of the length of the MD simulations. We show that there is a relatively poor one-to-one correspondence between eigenvectors obtained from two independent runs and conclude that caution should be taken when analyzing principal components individually. We also observe that increasing the simulation length does not improve the agreement with the experimental structural difference. In fact, relatively short MD simulations are sufficient for this purpose. We observe a rapid convergence of the eigenvectors (after ca. 6 ns). Although there is not always a clear one-to-one correspondence, there is a qualitatively good agreement between the movements described by the first five modes obtained with the three different approaches; PCA, all-atoms NMA, and coarse-grained NMA. It is particularly interesting to relate this to the computational cost of the three methods. The results we obtain on the GroEL subunit contribute to the generalization of robust and reproducible strategies for the study of protein dynamics, using either NMA or PCA of trajectories from MD simulations. © 2010 Wiley-Liss, Inc.

Data dependent systems approach to modal analysis Part 1: Theory

NASA Astrophysics Data System (ADS)

Pandit, S. M.; Mehta, N. P.

1988-05-01

The concept of Data Dependent Systems (DDS) and its applicability in the context of modal vibration analysis is presented. The ability of the DDS difference equation models to provide a complete representation of a linear dynamic system from its sampled response data forms the basis of the approach. The models are decomposed into deterministic and stochastic components so that system characteristics are isolated from noise effects. The modelling strategy is outlined, and the method of analysis associated with modal parameter identification is described in detail. Advantages and special features of the DDS methodology are discussed. Since the correlated noise is appropriately and automatically modelled by the DDS, the modal parameters are shown to be estimated very accurately and hence no preprocessing of the data is needed. Complex mode shapes and non-classical damping are as easily analyzed as the classical normal mode analysis. These features are illustrated by using simulated data in this Part I and real data on a disc-brake rotor in Part II.

Large-amplitude nonlinear normal modes of the discrete sine lattices.

PubMed

Smirnov, Valeri V; Manevitch, Leonid I

2017-02-01

We present an analytical description of the large-amplitude stationary oscillations of the finite discrete system of harmonically coupled pendulums without any restrictions on their amplitudes (excluding a vicinity of π). Although this model has numerous applications in different fields of physics, it was studied earlier in the infinite limit only. The discrete chain with a finite length can be considered as a well analytical analog of the coarse-grain models of flexible polymers in the molecular dynamics simulations. The developed approach allows to find the dispersion relations for arbitrary amplitudes of the nonlinear normal modes. We emphasize that the long-wavelength approximation, which is described by well-known sine-Gordon equation, leads to an inadequate zone structure for the amplitudes of about π/2 even if the chain is long enough. An extremely complex zone structure at the large amplitudes corresponds to multiple resonances between nonlinear normal modes even with strongly different wave numbers. Due to the complexity of the dispersion relations the modes with shorter wavelengths may have smaller frequencies. The stability of the nonlinear normal modes under condition of the resonant interaction are discussed. It is shown that this interaction of the modes in the vicinity of the long wavelength edge of the spectrum leads to the localization of the oscillations. The thresholds of instability and localization are determined explicitly. The numerical simulation of the dynamics of a finite-length chain is in a good agreement with obtained analytical predictions.

Polarization-modulated FTIR spectroscopy of lipid/gramicidin monolayers at the air/water interface.

PubMed Central

Ulrich, W P; Vogel, H

1999-01-01

Monolayers of gramicidin A, pure and in mixtures with dimyristoylphosphatidylcholine (DMPC), were studied in situ at the air/H2O and air/D2O interfaces by polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). Simulations of the entire set of amide I absorption modes were also performed, using complete parameter sets for different conformations based on published normal mode calculations. The structure of gramicidin A in the DMPC monolayer could clearly be assigned to a beta6.3 helix. Quantitative analysis of the amide I bands revealed that film pressures of up to 25-30 mN/m the helix tilt angle from the vertical in the pure gramicidin A layer exceeded 60 degrees. A marked dependence of the peptide orientation on the applied surface pressure was observed for the mixed lipid-peptide monolayers. At low pressure the helix lay flat on the surface, whereas at high pressures the helix was oriented almost parallel to the surface normal. PMID:10049344

Dynamics and structure of planetary rings

NASA Technical Reports Server (NTRS)

French, R. G.

1991-01-01

Recent research efforts were directed towards sharpening the understanding of kinematical and dynamical properties of the Uranian rings, with the combination of Earth-based and Voyager observations, and in obtaining and interpreting new observations of the Saturn system from the remarkable stellar occultation of 3 Jul. 1989. Some of the highlights studied include: (1) a detailed comparison of structure and dynamics of the Uranus rings from joint analysis of high quality Earth-based data and the complete set of Voyager occultation measurements; (2) a comprehensive search for weak normal modes excited in the Uranian rings, analogous to the m = 2 and m = 0 normal modes previously identified for the delta and gamma rings; (3) an ongoing search for faint rings and ring arcs of Uranus, using both Voyager images of the rings and Earth-based and spacecraft stellar occultation data; (4) a comparison of upper stratospheric temperatures of Uranus inferred from Voyager ultraviolet occultations with results of ground-based occultation observations; and (5) observations of the 3 Jul. 1989 Saturn occultation of 28 Sgr.

Synthetic Microwave Imaging Reflectometry diagnostic using 3D FDTD Simulations

NASA Astrophysics Data System (ADS)

Kruger, Scott; Jenkins, Thomas; Smithe, David; King, Jacob; Nimrod Team Team

2017-10-01

Microwave Imaging Reflectometry (MIR) has become a standard diagnostic for understanding tokamak edge perturbations, including the edge harmonic oscillations in QH mode operation. These long-wavelength perturbations are larger than the normal turbulent fluctuation levels and thus normal analysis of synthetic signals become more difficult. To investigate, we construct a synthetic MIR diagnostic for exploring density fluctuation amplitudes in the tokamak plasma edge by using the three-dimensional, full-wave FDTD code Vorpal. The source microwave beam for the diagnostic is generated and refelected at the cutoff surface that is distorted by 2D density fluctuations in the edge plasma. Synthetic imaging optics at the detector can be used to understand the fluctuation and background density profiles. We apply the diagnostic to understand the fluctuations in edge plasma density during QH-mode activity in the DIII-D tokamak, as modeled by the NIMROD code. This work was funded under DOE Grant Number DE-FC02-08ER54972.

Estimation of blade airloads from rotor blade bending moments

NASA Technical Reports Server (NTRS)

Bousman, William G.

1987-01-01

A method is developed to estimate the blade normal airloads by using measured flap bending moments; that is, the rotor blade is used as a force balance. The blade's rotation is calculated in vacuum modes and the airloads are then expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The modal amplitudes are identified from the blade bending moments using the Strain Pattern Analysis Method. The application of the method is examined using simulated flap bending moment data that have been calculated for measured airloads for a full-scale rotor in a wind tunnel. The estimated airloads are compared with the wind tunnel measurements. The effects of the number of measurements, the number of modes, and errors in the measurements and the blade properties are examined, and the method is shown to be robust.

Dual-band reflective polarization converter based on slotted wire resonators

NASA Astrophysics Data System (ADS)

Li, Fengxia; Zhang, Linbo; Zhou, Peiheng; Chen, Haiyan; Zhao, Rui; Zhou, Yang; Liang, Difei; Lu, Haipeng; Deng, Longjiang

2018-02-01

A dual-band and high-efficiency reflective linear polarization converter composed of a layer of slotted metal wires has been proposed. Both the simulated and experimental results indicate that the structure can convert a linearly polarized wave to its cross-polarized state for two distinct frequency bands under normal incidence: 9.8-15.1 and 19.2-25.7 GHz. This phenomenon is attributed to a resonance that corresponds to the "trapped mode" at 15.8 GHz. This mode is stable with structural parameters and incident angle at a relatively wide range, and thus becomes promising for dual-band (also multiband) devices design. By surface current distribution and electric field analysis, the operation mechanism has been illuminated, especially for the "trapped mode", identified by the equally but also oppositely directed currents in each unit cell.

Quantum control of the normal modes of benzene with ultrafast laser pulses

NASA Astrophysics Data System (ADS)

Sauer, Petra; Dou, Yusheng; Torralva, Ben; Allen, Roland

2005-03-01

Remarkable innovations in laser technology have made it possible to create laser pulses with ultrashort durations (below 100 femtoseconds) and ultrahigh intensities (above 1 terawatt per cm^2). To understand the behavior of complex molecules and materials in this new regime of physics, chemistry, biology, and materials science requires innovative techniques which complement experiment and standard theory, and which can treat situations in which conventional approximations like the Born- Oppenheimer approximation, the Franck-Condon principle, and Fermi's golden rule are no longer valid. In this talk we describe a method that we are developing, semiclassical electron-radiation-ion dyanmics (SERID), which can be used to perform simulations of the coupled dynamics of electrons and nuclei in an intense radiation field. We have employed this technique in studying the normal modes of benzene, and the possibility of controlling these modes by optimizing the laser pulses that are applied to the molecule. Animations will be shown of particular normal modes, including the breathing and beating modes, illustrating their symmetries and other properties, and of the photodissociation of benzene when the laser pulse exceeds a threshold intensity.

The New Data Assimilation System at the Italian Air Force Weather Service: Design and Preliminary Results

DTIC Science & Technology

2002-09-01

weather conditions (1999 Christmas storm in Europe , January 2000 snow storm over the eastern coast of the US) can be attributed to the inaccuracies in...over the normal modes of a linearized version of the model equations. These 5 normal modes can be classified (at least for the extratropics ) based

Fluctuations and discrete particle noise in gyrokinetic simulation of drift waves

NASA Astrophysics Data System (ADS)

Jenkins, Thomas G.; Lee, W. W.

2007-03-01

The relevance of the gyrokinetic fluctuation-dissipation theorem (FDT) to thermal equilibrium and nonequilibrium states of the gyrokinetic plasma is explored, with particular focus being given to the contribution of weakly damped normal modes to the fluctuation spectrum. It is found that the fluctuation energy carried in the normal modes exhibits the proper scaling with particle count (as predicted by the FDT in thermal equilibrium) even in the presence of drift waves, which grow linearly and attain a nonlinearly saturated steady state. This favorable scaling is preserved, and the saturation amplitude of the drift wave unaffected, for parameter regimes in which the normal modes become strongly damped and introduce a broad spectrum of discreteness-induced background noise in frequency space.

The effect of time synchronization of wireless sensors on the modal analysis of structures

NASA Astrophysics Data System (ADS)

Krishnamurthy, V.; Fowler, K.; Sazonov, E.

2008-10-01

Driven by the need to reduce the installation cost and maintenance cost of structural health monitoring (SHM) systems, wireless sensor networks (WSNs) are becoming increasingly popular. Perfect time synchronization amongst the wireless sensors is a key factor enabling the use of low-cost, low-power WSNs for structural health monitoring applications based on output-only modal analysis of structures. In this paper we present a theoretical framework for analysis of the impact created by time delays in the measured system response on the reconstruction of mode shapes using the popular frequency domain decomposition (FDD) technique. This methodology directly estimates the change in mode shape values based on sensor synchronicity. We confirm the proposed theoretical model by experimental validation in modal identification experiments performed on an aluminum beam. The experimental validation was performed using a wireless intelligent sensor and actuator network (WISAN) which allows for close time synchronization between sensors (0.6-10 µs in the tested configuration) and guarantees lossless data delivery under normal conditions. The experimental results closely match theoretical predictions and show that even very small delays in output response impact the mode shapes.

State-to-state mode selectivity in the HD + OH reaction: Perspectives from two product channels

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

Zhao, Bin; Guo, Hua, E-mail: hguo@unm.edu; Sun, Zhigang

The state-to-state quantum dynamics (J{sub tot} = 0) of the HD + OH(υ{sub 2} = 0, 1) reaction is studied using a reactant coordinate based method, which allows the analysis of both the H + DOH and D + HOH channels with a single propagation. The stretching vibration of the newly formed bond, namely, the OD bond in DOH and one OH bond in HOH, is excited, thanks to its strong coupling with the reaction coordinate at the transition state. On the other hand, the vibrational energy deposited into the OH reactant (υ{sub 2} = 1) is sequestered during themore » reaction in the spectator OH mode. The combined effect leads to the excitation of both the OD and OH stretching modes in the DOH product, and the dominance of the (002) normal-mode state population in the HOH product, which in the local-mode picture corresponds to the excitation of both OH bonds with one quantum each. The energy flow in this prototypical tetratomic reaction can be understood in terms of the sudden vector projection model.« less

Initial transport validation studies using NSTX-U L-mode plasmas

NASA Astrophysics Data System (ADS)

Guttenfelder, Walter; Battaglia, D.; Bell, R. E.; Boyer, M. D.; Crocker, N.; Diallo, A.; Ferraro, N.; Gerhardt, S. P.; Kaye, S. M.; Leblanc, B. P.; Liu, D.; Menard, J. E.; Mueller, D.; Myer, C.; Podesta, M.; Raman, R.; Ren, Y.; Sabbagh, S.; Smith, D.

2016-10-01

A variety of stationary L-mode plasmas have been successfully developed in NSTX-U for physics validation studies. The plasmas span a range of density (1-4 ×1019 m-3) , plasma current (0.65-1.0 MA), and neutral beam heating power (<=4 MW), taking advantage of new, more tangential neutral beam sources to vary rotation profiles. Transport analysis (TRANSP) and turbulence measurements (BES, reflectometry) of these plasmas will be illustrated and compared with initial microstability and transport predictions. In particular, the normalized beta of these L-modes range between βN = 1-2, providing a valuable bridge in parameter space between (i) H-modes at comparable beta in conventional tokamaks (R/a 3, βN 2), where transport models have been largely developed and tested, and (ii) low-aspect-ratio H-modes at higher beta (R/a 1.5-1.7, βN 5), where transport models are less tested and challenged by stronger electromagnetic and equilibrium effects. This work is supported by US DOE contract DE-AC02-09CH11466.

First principles study of vibrational dynamics of ceria-titania hybrid clusters

NASA Astrophysics Data System (ADS)

Majid, Abdul; Bibi, Maryam

2017-04-01

Density functional theory based calculations were performed to study vibrational properties of ceria, titania, and ceria-titania hybrid clusters. The findings revealed the dominance of vibrations related to oxygen when compared to those of metallic atoms in the clusters. In case of hybrid cluster, the softening of normal modes related to exterior oxygen atoms in ceria and softening/hardening of high/low frequency modes related to titania dimmers are observed. The results calculated for monomers conform to symmetry predictions according to which three IR and three Raman active modes were detected for TiO2, whereas two IR active and one Raman active modes were observed for CeO2. The comparative analysis indicates that the hybrid cluster CeTiO4 contains simultaneous vibrational fingerprints of the component dimmers. The symmetry, nature of vibrations, IR and Raman activity, intensities, and atomic involvement in different modes of the clusters are described in detail. The study points to engineering of CeTiO4 to tailor its properties for technological visible region applications in photocatalytic and electrochemical devices.

The effect of spin induced magnetization on Jeans instability of viscous and resistive quantum plasma

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

Sharma, Prerana, E-mail: preranaiitd@rediffmail.com; Chhajlani, R. K.

2014-03-15

The effect of spin induced magnetization and electrical resistivity incorporating the viscosity of the medium is examined on the Jeans instability of quantum magnetoplasma. Formulation of the system is done by using the quantum magnetohydrodynamic model. The analysis of the problem is carried out by normal mode analysis theory. The general dispersion relation is derived from set of perturbed equations to analyse the growth rate and condition of self-gravitational Jeans instability. To discuss the influence of resistivity, magnetization, and viscosity parameters on Jeans instability, the general dispersion relation is reduced for both transverse and longitudinal mode of propagations. In themore » case of transverse propagation, the gravitating mode is found to be affected by the viscosity, magnetization, resistivity, and magnetic field strength whereas Jeans criterion of instability is modified by the magnetization and quantum parameter. In the longitudinal mode of propagation, the gravitating mode is found to be modified due to the viscosity and quantum correction in which the Jeans condition of instability is influenced only by quantum parameter. The other non-gravitating Alfven mode in this direction is affected by finite electrical resistivity, spin induced magnetization, and viscosity. The numerical study for the growth rate of Jeans instability is carried out for both in the transverse and longitudinal direction of propagation to the magnetic field. The effect of various parameters on the growth rate of Jeans instability in quantum plasma is analysed.« less

Cerebrovascular pattern improved by ozone autohemotherapy: an entropy-based study on multiple sclerosis patients.

PubMed

Molinari, Filippo; Rimini, Daniele; Liboni, William; Acharya, U Rajendra; Franzini, Marianno; Pandolfi, Sergio; Ricevuti, Giovanni; Vaiano, Francesco; Valdenassi, Luigi; Simonetti, Vincenzo

2017-08-01

Ozone major autohemotherapy is effective in reducing the symptoms of multiple sclerosis (MS) patients, but its effects on brain are still not clear. In this work, we have monitored the changes in the cerebrovascular pattern of MS patients and normal subjects during major ozone autohemotherapy by using near-infrared spectroscopy (NIRS) as functional and vascular technique. NIRS signals are analyzed using a combination of time, time-frequency analysis and nonlinear analysis of intrinsic mode function signals obtained from empirical mode decomposition technique. Our results show that there is an improvement in the cerebrovascular pattern of all subjects indicated by increasing the entropy of the NIRS signals. Hence, we can conclude that the ozone therapy increases the brain metabolism and helps to recover from the lower activity levels which is predominant in MS patients.

PROP3D: A Program for 3D Euler Unsteady Aerodynamic and Aeroelastic (Flutter and Forced Response) Analysis of Propellers. Version 1.0

NASA Technical Reports Server (NTRS)

Srivastava, R.; Reddy, T. S. R.

1996-01-01

This guide describes the input data required, for steady or unsteady aerodynamic and aeroelastic analysis of propellers and the output files generated, in using PROP3D. The aerodynamic forces are obtained by solving three dimensional unsteady, compressible Euler equations. A normal mode structural analysis is used to obtain the aeroelastic equations, which are solved using either time domain or frequency domain solution method. Sample input and output files are included in this guide for steady aerodynamic analysis of single and counter-rotation propellers, and aeroelastic analysis of single-rotation propeller.

Mutual friction in a cold color-flavor-locked superfluid and r-mode instabilities in compact stars.

PubMed

Mannarelli, Massimo; Manuel, Cristina; Sa'd, Basil A

2008-12-12

Dissipative processes acting in rotating neutron stars are essential in preventing the growth of the r-mode instability. We estimate the damping time of r modes of a hypothetical compact quark star made up by color-flavor-locked quark matter at a temperature T < or approximately 0.01 MeV. The dissipation that we consider is due to the mutual friction force between the normal and the superfluid component arising from the elastic scattering of phonons with quantized vortices. This process is the dominant one for temperatures T < or approximately 0.01 MeV, where the mean free path of phonons due to their self-interactions is larger than the radius of the star. We find that r-mode oscillations are efficiently damped by this mechanism for pulsars rotating at frequencies of the order of 1 Hz at most. Our analysis rules out the possibility that cold pulsars rotating at higher frequencies are entirely made up by color-flavor-locked quark matter.

New SERS Substrates For Polycyclic Aromatic Hydrocarbon (PAH) Detection: Towards Quantitative SERS Sensors For Environmental Analysis

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

Peron, O.; Laboratoire de Nanotechnologie et d'instrumentation Optique, Institut Charles Delaunay, FRE 2848, Universite de technologie de Troyes, 12 rue Marie Curie, 10010 Troyes; Rinnert, E.

2010-08-06

In the investigation of chemical pollutions, such as PAHs (Polycyclic Aromatic Hydrocarbons) at low concentration in aqueous medium, surface-enhanced Raman scattering (SERS) stands for an alternative to the inherent low cross-section of normal Raman scattering. Indeed, SERS is a very sensitive spectroscopic technique due to the excitation of the surface plasmon modes of the nanostructured metallic film.

Aberrant functional connectivity of default-mode network in type 2 diabetes patients.

PubMed

Cui, Ying; Jiao, Yun; Chen, Hua-Jun; Ding, Jie; Luo, Bing; Peng, Cheng-Yu; Ju, Sheng-Hong; Teng, Gao-Jun

2015-11-01

Type 2 diabetes mellitus is associated with increased risk for dementia. Patients with impaired cognition often show default-mode network disruption. We aimed to investigate the integrity of a default-mode network in diabetic patients by using independent component analysis, and to explore the relationship between network abnormalities, neurocognitive performance and diabetic variables. Forty-two patients with type 2 diabetes and 42 well-matched healthy controls were included and underwent resting-state functional MRI in a 3 Tesla unit. Independent component analysis was adopted to extract the default-mode network, including its anterior and posterior components. Z-maps of both sub-networks were compared between the two groups and correlated with each clinical variable. Patients showed increased connectivity around the medial prefrontal cortex in the anterior sub-network, but decreased connectivity around the posterior cingulate cortex in the posterior sub-network. The decreased connectivity in the posterior part was significantly correlated with the score on Complex Figure Test-delay recall test (r = 0.359, p = 0.020), the time spent on Trail-Making Test-part B (r = -0.346, p = 0.025) and the insulin resistance level (r = -0.404, p = 0.024). Dissociation pattern in the default-mode network was found in diabetic patients, which might provide powerful new insights into the neural mechanisms that underlie the diabetes-related cognitive decline. • Type 2 diabetes mellitus is associated with impaired cognition • Default- mode network plays a central role in maintaining normal cognition • Network connectivity within the default mode was disrupted in type 2 diabetes patients • Decreased network connectivity was correlated with cognitive performance and insulin resistance level • Disrupted default-mode network might explain the impaired cognition in diabetic population.

Instabilities and subharmonic resonances of subsonic heated round jets, volume 2. Ph.D. Thesis Final Report

NASA Technical Reports Server (NTRS)

Ng, Lian Lai

1990-01-01

When a jet is perturbed by a periodic excitation of suitable frequency, a large-scale coherent structure develops and grows in amplitude as it propagates downstream. The structure eventually rolls up into vortices at some downstream location. The wavy flow associated with the roll-up of a coherent structure is approximated by a parallel mean flow and a small, spatially periodic, axisymmetric wave whose phase velocity and mode shape are given by classical (primary) stability theory. The periodic wave acts as a parametric excitation in the differential equations governing the secondary instability of a subharmonic disturbance. The (resonant) conditions for which the periodic flow can strongly destabilize a subharmonic disturbance are derived. When the resonant conditions are met, the periodic wave plays a catalytic role to enhance the growth rate of the subharmonic. The stability characteristics of the subharmonic disturbance, as a function of jet Mach number, jet heating, mode number and the amplitude of the periodic wave, are studied via a secondary instability analysis using two independent but complementary methods: (1) method of multiple scales, and (2) normal mode analysis. It is found that the growth rates of the subharmonic waves with azimuthal numbers beta = 0 and beta = 1 are enhanced strongly, but comparably, when the amplitude of the periodic wave is increased. Furthermore, compressibility at subsonic Mach numbers has a moderate stabilizing influence on the subharmonic instability modes. Heating suppresses moderately the subharmonic growth rate of an axisymmetric mode, and it reduces more significantly the corresponding growth rate for the first spinning mode. Calculations also indicate that while the presence of a finite-amplitude periodic wave enhances the growth rates of subharmonic instability modes, it minimally distorts the mode shapes of the subharmonic waves.

Relationships between nonlinear normal modes and response to random inputs

DOE PAGES

Schoneman, Joseph D.; Allen, Matthew S.; Kuether, Robert J.

2016-07-25

The ability to model nonlinear structures subject to random excitation is of key importance in designing hypersonic aircraft and other advanced aerospace vehicles. When a structure is linear, superposition can be used to construct its response to a known spectrum in terms of its linear modes. Superposition does not hold for a nonlinear system, but several works have shown that a system's dynamics can still be understood qualitatively in terms of its nonlinear normal modes (NNMs). Here, this work investigates the connection between a structure's undamped nonlinear normal modes and the spectrum of its response to high amplitude random forcing.more » Two examples are investigated: a spring-mass system and a clamped-clamped beam modeled within a geometrically nonlinear finite element package. In both cases, an intimate connection is observed between the smeared peaks in the response spectrum and the frequency-energy dependence of the nonlinear normal modes. In order to understand the role of coupling between the underlying linear modes, reduced order models with and without modal coupling terms are used to separate the effect of each NNM's backbone from the nonlinear couplings that give rise to internal resonances. In the cases shown here, uncoupled, single-degree-of-freedom nonlinear models are found to predict major features in the response with reasonable accuracy; a highly inexpensive approximation such as this could be useful in design and optimization studies. More importantly, the results show that a reduced order model can be expected to give accurate results only if it is also capable of accurately predicting the frequency-energy dependence of the nonlinear modes that are excited.« less

Sunrise/sunset thermal shock disturbance analysis and simulation for the TOPEX satellite

NASA Technical Reports Server (NTRS)

Dennehy, C. J.; Welch, R. V.; Zimbelman, D. F.

1990-01-01

It is shown here that during normal on-orbit operations the TOPEX low-earth orbiting satellite is subjected to an impulsive disturbance torque caused by rapid heating of its solar array when entering and exiting the earth's shadow. Error budgets and simulation results are used to demonstrate that this sunrise/sunset torque disturbance is the dominant Normal Mission Mode (NMM) attitude error source. The detailed thermomechanical modeling, analysis, and simulation of this torque is described, and the predicted on-orbit performance of the NMM attitude control system in the face of the sunrise/sunset disturbance is presented. The disturbance results in temporary attitude perturbations that exceed NMM pointing requirements. However, they are below the maximum allowable pointing error which would cause the radar altimeter to break lock.

Modeling backbone flexibility to achieve sequence diversity: The design of novel alpha-helical ligands for Bcl-xL

PubMed Central

Fu, Xiaoran; Apgar, James R.; Keating, Amy E.

2007-01-01

Computational protein design can be used to select sequences that are compatible with a fixed-backbone template. This strategy has been used in numerous instances to engineer novel proteins. However, the fixed-backbone assumption severely restricts the sequence space that is accessible via design. For challenging problems, such as the design of functional proteins, this may not be acceptable. In this paper, we present a method for introducing backbone flexibility into protein design calculations and apply it to the design of diverse helical BH3 ligands that bind to the anti-apoptotic protein Bcl-xL, a member of the Bcl-2 protein family. We demonstrate how normal mode analysis can be used to sample different BH3 backbones, and show that this leads to a larger and more diverse set of low-energy solutions than can be achieved using a native high-resolution Bcl-xL complex crystal structure as a template. We tested several of the designed solutions experimentally and found that this approach worked well when normal mode calculations were used to deform a native BH3 helix structure, but less well when they were used to deform an idealized helix. A subsequent round of design and testing identified a likely source of the problem as inadequate sampling of the helix pitch. In all, we tested seventeen designed BH3 peptide sequences, including several point mutants. Of these, eight bound well to Bcl-xL and four others showed weak but detectable binding. The successful designs showed a diversity of sequences that would have been difficult or impossible to achieve using only a fixed backbone. Thus, introducing backbone flexibility via normal mode analysis effectively broadened the set of sequences identified by computational design, and provided insight into positions important for binding Bcl-xL. PMID:17597151

Normal Fault and Tensile Fissure Network Development Around an Off-Axis Silica-Rich Volcanic Dome of the Alarcon Rise, Southern Gulf of California

NASA Astrophysics Data System (ADS)

Contreras, J.; Vega-Ramirez, L. A.; Spelz, R. M.; Portner, R. A.; Clague, D. A.

2017-12-01

The Monterey Bay Aquarium Research Institute collected in 2012 and 2015 high-resolution (1 m horizontal/0.2 m vertical) bathymetry data in the southern Gulf of California using an autonomous underwater vehicle (AUV) that bring to light an extensive array of normal faults and fissures cutting lava domes and smaller volcanic cones, pillow mounds and lava sheet flows of variable compositions along the Alarcon rise. Active faulting and fissure growth in the transition between the neovolcanic zone and adjacent axial summit trough, in a 6.9 x 1.5 km2 area at the NE segment of the rise, developed at some point between 6 Ka B.P. (14C) and the present time. We performed a population analysis of fracture networks imaged by the AUV that reveal contrasting scaling attributes between mode I (opening) and mode III (shearing) extensional structures. Opening-mode fractures are spatially constrained to narrow bands 400 m wide. The youngest set developed on pillow lavas 800 yr old (14C) of the neovolcanic zone. Regions of normal fault propagation by anti-plane shearing alternate with the tensile-fracture growth areas. This provides evidence for permutations in space of the stress field across the ridge axis. Moreover, fault-length frequency plots for both fracture networks show that opening-mode fractures are best fit using an exponential relationship whereas normal faults are best fit using a power-law relationship. These size distributions indicate tensile fractures rapidly reached a saturated state in which large fractures (102 m) accommodate most of the strain and appear to be constrained to a thin mechanical/thermal layer. Faults, by contrast, have slowly evolved to a state of self-organization characterized by growth by linkage with neighboring faults in the strike direction forming fault arrays with a maximum length of 2km. We also analyzed the development of faults in the vicinity of an off-axis rhyolitic dome. We find that faults have asymmetric, half-restricted slip profiles with abrupt displacement gradients towards the dome. We further document a strain deficit in normal faulting near the dome. We suggest that these observations reflect the control that changes in mechanical properties and rheology may exert on fault slip localization by effectively suppressing fault nucleation and propagation.

Excitation power quantities in phase resonance testing of nonlinear systems with phase-locked-loop excitation

NASA Astrophysics Data System (ADS)

Peter, Simon; Leine, Remco I.

2017-11-01

Phase resonance testing is one method for the experimental extraction of nonlinear normal modes. This paper proposes a novel method for nonlinear phase resonance testing. Firstly, the issue of appropriate excitation is approached on the basis of excitation power considerations. Therefore, power quantities known from nonlinear systems theory in electrical engineering are transferred to nonlinear structural dynamics applications. A new power-based nonlinear mode indicator function is derived, which is generally applicable, reliable and easy to implement in experiments. Secondly, the tuning of the excitation phase is automated by the use of a Phase-Locked-Loop controller. This method provides a very user-friendly and fast way for obtaining the backbone curve. Furthermore, the method allows to exploit specific advantages of phase control such as the robustness for lightly damped systems and the stabilization of unstable branches of the frequency response. The reduced tuning time for the excitation makes the commonly used free-decay measurements for the extraction of backbone curves unnecessary. Instead, steady-state measurements for every point of the curve are obtained. In conjunction with the new mode indicator function, the correlation of every measured point with the associated nonlinear normal mode of the underlying conservative system can be evaluated. Moreover, it is shown that the analysis of the excitation power helps to locate sources of inaccuracies in the force appropriation process. The method is illustrated by a numerical example and its functionality in experiments is demonstrated on a benchmark beam structure.

The anti-cataract molecular mechanism study in selenium cataract rats for baicalin ophthalmic nanoparticles.

PubMed

Li, Nan; Han, Zhenzhen; Li, Lin; Zhang, Bing; Liu, Zhidong; Li, Jiawei

2018-01-01

The objective of this study was to investigate the effects of the solid lipid nanoparticles of baicalin (BA-SLNs) on an experimental cataract model and explore the molecular mechanism combined with bioinformatics analysis. The transparency of lens was observed daily by slit-lamp and photography. Lenticular opacity was graded. Two-dimensional gel electrophoresis (2-DE) was employed to analyze the differential protein expression modes in each group. Proteins of interest were subjected to protein identification by nano-liquid chromatography tandem mass spectrometry (LC-MS/MS). Bioinformatics analysis was performed using the Ingenuity Pathway Analysis (IPA) online software to comprehend the biological implications of the proteins identified by proteomics. At the end of the sodium selenite-induced cataract progression, almost all lenses from the model group developed partial nuclear opacity; however, all lenses were clear and normal in the blank group. There was no significant difference between the BA-SLNs group and the blank group. Many protein spots were differently expressed in 2-DE patterns of total proteins of lenses from each group, and 65 highly different protein spots were selected to be identified between the BA-SLNs group and the model group. A total of 23 proteins were identified, and 12 of which were crystalline proteins. We considered crystalline proteins to play important roles in preserving the normal expression levels of proteins and the transparency of lenses. The general trend in the BA-SLN-treated lenses' data showed that BA-SLNs regulated the protein expression mode of cataract lenses to normal lenses. Our findings suggest that BA-SLNs may be a potential therapeutic agent in treating cataract by regulating protein expression and may also be a strong candidate for future clinical research.

The Properties of the Massive Star-forming Galaxies with an Outside-in Assembly Mode

NASA Astrophysics Data System (ADS)

Wang, Enci; Kong, Xu; Wang, Huiyuan; Wang, Lixin; Lin, Lin; Gao, Yulong; Liu, Qing

2017-08-01

Previous findings show that massive ({M}* > {10}10 {M}⊙ ) star-forming (SF) galaxies usually have an “inside-out” stellar mass assembly mode. In this paper, we have for the first time selected a sample of 77 massive SF galaxies with an “outside-in” assembly mode (called the “targeted sample”) from the Mapping Nearby Galaxies at the Apache Point Observatory (MaNGA) survey. For comparison, two control samples are constructed from the MaNGA sample matched in stellar mass: a sample of 154 normal SF galaxies and a sample of 62 quiescent galaxies. In contrast to normal SF galaxies, the targeted galaxies appear to be smoother and more bulge-dominated and have a smaller size and higher concentration, star formation rate, and gas-phase metallicity as a whole. However, they have a larger size and lower concentration than quiescent galaxies. Unlike the normal SF sample, the targeted sample exhibits a slightly positive gradient of the 4000 Å break and a pronounced negative gradient of Hα equivalent width. Furthermore, the median surface mass density profile is between those of the normal SF and quiescent samples, indicating that the gas accretion of quiescent galaxies is not likely to be the main approach for the outside-in assembly mode. Our results suggest that the targeted galaxies are likely in the transitional phase from normal SF galaxies to quiescent galaxies, with rapid ongoing central stellar mass assembly (or bulge growth). We discuss several possible formation mechanisms for the outside-in mass assembly mode.

Multibody dynamics: Modeling component flexibility with fixed, free, loaded, constraint, and residual modes

NASA Technical Reports Server (NTRS)

Spanos, John T.; Tsuha, Walter S.

1989-01-01

The assumed-modes method in multibody dynamics allows the elastic deformation of each component in the system to be approximated by a sum of products of spatial and temporal functions commonly known as modes and modal coordinates respectively. The choice of component modes used to model articulating and non-articulating flexible multibody systems is examined. Attention is directed toward three classical Component Mode Synthesis (CMS) methods whereby component normal modes are generated by treating the component interface (I/F) as either fixed, free, or loaded with mass and stiffness contributions from the remaining components. The fixed and free I/F normal modes are augmented by static shape functions termed constraint and residual modes respectively. A mode selection procedure is outlined whereby component modes are selected from the Craig-Bampton (fixed I/F plus constraint), MacNeal-Rubin (free I/F plus residual), or Benfield-Hruda (loaded I/F) mode sets in accordance with a modal ordering scheme derived from balance realization theory. The success of the approach is judged by comparing the actuator-to-sensor frequency response of the reduced order system with that of the full order system over the frequency range of interest. A finite element model of the Galileo spacecraft serves as an example in demonstrating the effectiveness of the proposed mode selection method.

Comparison analysis on the thermal runaway of lithium-ion battery under two heating modes.

PubMed

Wu, Tangqin; Chen, Haodong; Wang, Qingsong; Sun, Jinhua

2018-02-15

The thermal stability evaluation of materials in a soft-pack commercial cell is tested using C80 calorimeter, including anode, cathode, separator and full cell (mixing of the three materials including additional electrolyte). Thermal runaway characteristic of the commercial cell is tested on the accelerating rate calorimeter (ARC) with two heating modes, including internal heating mode and external heating mode. The results show that the thermal stability of internal material for tested cell follows the below order: anode

Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

NASA Astrophysics Data System (ADS)

Anderson, M. W.; O'Neil, T. M.; Dubin, D. H. E.; Gould, R. W.

2011-10-01

In the cold-fluid dispersion relation ω =ωp/[1+(k⊥/kz)2]1/2 for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k⊥/kz. As a result, for any frequency ω <ωp, there are infinitely many degenerate waves, all having the same value of k⊥/kz. On a cold finite-length plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz /dr=±(ωp2/ω2-1)1/2. Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

Reliable before-fabrication forecasting of normal and touch mode MEMS capacitive pressure sensor: modeling and simulation

NASA Astrophysics Data System (ADS)

Jindal, Sumit Kumar; Mahajan, Ankush; Raghuwanshi, Sanjeev Kumar

2017-10-01

An analytical model and numerical simulation for the performance of MEMS capacitive pressure sensors in both normal and touch modes is required for expected behavior of the sensor prior to their fabrication. Obtaining such information should be based on a complete analysis of performance parameters such as deflection of diaphragm, change of capacitance when the diaphragm deflects, and sensitivity of the sensor. In the literature, limited work has been carried out on the above-stated issue; moreover, due to approximation factors of polynomials, a tolerance error cannot be overseen. Reliable before-fabrication forecasting requires exact mathematical calculation of the parameters involved. A second-order polynomial equation is calculated mathematically for key performance parameters of both modes. This eliminates the approximation factor, and an exact result can be studied, maintaining high accuracy. The elimination of approximation factors and an approach of exact results are based on a new design parameter (δ) that we propose. The design parameter gives an initial hint to the designers on how the sensor will behave once it is fabricated. The complete work is aided by extensive mathematical detailing of all the parameters involved. Next, we verified our claims using MATLAB® simulation. Since MATLAB® effectively provides the simulation theory for the design approach, more complicated finite element method is not used.

CIMEL Measurements of Zenith Radiances at the ARM Site

NASA Technical Reports Server (NTRS)

Marshak, Alexander; Wiscombe, Warren; Lau, William K. M. (Technical Monitor)

2002-01-01

Starting from October 1, 2001, Cimel at the ARM Central Facility in Oklahoma has been switched to a new "cloud mode." This mode allows taking measurements of zenith radiance when the Sun in blocked by clouds. In this case, every 13 min. Cimel points straight up and takes 10 measurements with 9 sec. time interval. The new Cimel's mode has four filters at 440, 670, 870 and 1020 nm. For cloudy conditions, the spectral contrast in surface albedo dominates over Rayleigh and aerosol effects; this makes normalized zenith radiances at 440 and 670 as well as for 870 and 1020 almost indistinguishable. We compare Cimel measurements with other ARM cart site instruments: Multi-Filter Rotating Shadowband Radiometer (MFRSR), Narrow Field of View (NFOV) sensor, and MicroWave Radiometer(MWR). Based on Cimel and MFRSR 670 and 870 nm channels, we build a normalized difference cloud index (NDCI) for radiances and fluxes, respectively. Radiance NDCI from Cimel and flux NDCI from MFRSR are compared between themselves as well as with cloud Liquid Water Path (LWP) retrieved from MWR. Based on our theoretical calculations and preliminary data analysis,there is a good correlation between NDCIs and LWP for cloudy sky above green vegetation. Based on this correlation, an algorithm to retrieve cloud optical depth from NDCI is proposed.

33 CFR 162.138 - Connecting waters from Lake Huron to Lake Erie; speed rules.

Code of Federal Regulations, 2010 CFR

2010-07-01

... vessels in normal displacement mode. (1) Except when required for the safety of the vessel or any other vessel, vessels of 20 meters or more in length operating in normal displacement mode shall proceed at a... than displacement of its weight in the water, to an extent such that the wake which would otherwise be...

33 CFR 162.138 - Connecting waters from Lake Huron to Lake Erie; speed rules.

Code of Federal Regulations, 2011 CFR

2011-07-01

... vessels in normal displacement mode. (1) Except when required for the safety of the vessel or any other vessel, vessels of 20 meters or more in length operating in normal displacement mode shall proceed at a... than displacement of its weight in the water, to an extent such that the wake which would otherwise be...

On new non-modal hydrodynamic stability modes and resulting non-exponential growth rates - a Lie symmetry approach

NASA Astrophysics Data System (ADS)

Oberlack, Martin; Nold, Andreas; Sanjon, Cedric Wilfried; Wang, Yongqi; Hau, Jan

2016-11-01

Classical hydrodynamic stability theory for laminar shear flows, no matter if considering long-term stability or transient growth, is based on the normal-mode ansatz, or, in other words, on an exponential function in space (stream-wise direction) and time. Recently, it became clear that the normal mode ansatz and the resulting Orr-Sommerfeld equation is based on essentially three fundamental symmetries of the linearized Euler and Navier-Stokes equations: translation in space and time and scaling of the dependent variable. Further, Kelvin-mode of linear shear flows seemed to be an exception in this context as it admits a fourth symmetry resulting in the classical Kelvin mode which is rather different from normal-mode. However, very recently it was discovered that most of the classical canonical shear flows such as linear shear, Couette, plane and round Poiseuille, Taylor-Couette, Lamb-Ossen vortex or asymptotic suction boundary layer admit more symmetries. This, in turn, led to new problem specific non-modal ansatz functions. In contrast to the exponential growth rate in time of the modal-ansatz, the new non-modal ansatz functions usually lead to an algebraic growth or decay rate, while for the asymptotic suction boundary layer a double-exponential growth or decay is observed.

Local vibrational modes of the formic acid dimer - the strength of the double hydrogen bond

NASA Astrophysics Data System (ADS)

Kalescky, R.; Kraka, E.; Cremer, D.

2013-07-01

The 24 normal and 24 local vibrational modes of the formic acid dimer formed by two trans formic acid monomers to a ring (TT1) are analysed utilising preferentially experimental frequencies, but also CCSD(T)/CBS and ωB97X-D harmonic vibrational frequencies. The local hydrogen bond (HB) stretching frequencies are at 676 cm-1 and by this 482 and 412 cm-1 higher compared to the measured symmetric and asymmetric HB stretching frequencies at 264 and 194 cm-1. The adiabatic connection scheme between local and normal vibrational modes reveals that the lowering is due to the topology of dimer TT1, mass coupling, and avoided crossings involving the HṡṡṡOC bending modes. The HB local mode stretching force constant is related to the strength of the HB whereas the normal mode stretching force constant and frequency lead to an erroneous underestimation of the HB strength. The HB in TT1 is stabilised by electron delocalisation in the O=C-O units fostered by forming a ring via double HBs. This implies that the CO apart from the OH local stretching frequencies reflect the strength of the HB via their red or blue shifts relative to their corresponding values in trans formic acid.

A Guided Tour of Mathematical Methods

NASA Astrophysics Data System (ADS)

Snieder, Roel

2009-04-01

1. Introduction; 2. Dimensional analysis; 3. Power series; 4. Spherical and cylindrical co-ordinates; 5. The gradient; 6. The divergence of a vector field; 7. The curl of a vector field; 8. The theorem of Gauss; 9. The theorem of Stokes; 10. The Laplacian; 11. Conservation laws; 12. Scale analysis; 13. Linear algebra; 14. The Dirac delta function; 15. Fourier analysis; 16. Analytic functions; 17. Complex integration; 18. Green's functions: principles; 19. Green's functions: examples; 20. Normal modes; 21. Potential theory; 22. Cartesian tensors; 23. Perturbation theory; 24. Asymptotic evaluation of integrals; 25. Variational calculus; 26. Epilogue, on power and knowledge; References.

Characterization of crack growth under combined loading

NASA Technical Reports Server (NTRS)

Feldman, A.; Smith, F. W.; Holston, A., Jr.

1977-01-01

Room-temperature static and cyclic tests were made on 21 aluminum plates in the shape of a 91.4x91.4-cm Maltese cross with 45 deg flaws to develop crack growth and fracture toughness data under mixed-mode conditions. During cyclic testing, it was impossible to maintain a high proportion of shear-mode deformation on the crack tips. Cracks either branched or turned. Under static loading, cracks remained straight if shear stress intensity exceeded normal stress intensity. Mixed-mode crack growth rate data compared reasonably well with published single-mode data, and measured crack displacements agreed with the straight and branched crack analyses. Values of critical strain energy release rate at fracture for pure shear were approximately 50% higher than for pure normal opening, and there was a large reduction in normal stress intensity at fracture in the presence of high shear stress intensity. Net section stresses were well into the inelastic range when fracture occurred under high shear on the cracks.

Black phosphorus as a saturable absorber for generating mode-locked fiber laser in normal dispersion regime

NASA Astrophysics Data System (ADS)

Latiff, A. A.; Rusdi, M. F. M.; Hisyam, M. B.; Ahmad, H.; Harun, S. W.

2016-11-01

This paper reports a few-layer black phosphorus (BP) as a saturable absorber (SA) or phase-locker in generating modelocked pulses from a double-clad ytterbium-doped fiber laser (YDFL). We mechanically exfoliated the BP flakes from BP crystal through a scotch tape, and repeatedly press until the flakes thin and spread homogenously. Then, a piece of BP tape was inserted in the cavity between two fiber connectors end facet. Under 810 mW to 1320 mW pump power, stable mode-locked operation at 1085 nm with a repetition rate of 13.4 MHz is successfully achieved in normal dispersion regime. Before mode-locked operation disappears above maximum pump, the output power and pulse energy is about 80 mW and 6 nJ, respectively. This mode-locked laser produces peak power of 0.74 kW. Our work may validates BP SA as a phase-locker related to two-dimensional nanomaterials and pulsed generation in normal dispersion regime.

Estimating Blade Section Airloads from Blade Leading-Edge Pressure Measurements

NASA Technical Reports Server (NTRS)

vanAken, Johannes M.

2003-01-01

The Tilt-Rotor Aeroacoustic Model (TRAM) test in the Duitse-Nederlandse Wind (DNW) Tunnel acquired blade pressure data for forward flight test conditions of a tiltrotor in helicopter mode. Chordwise pressure data at seven radial locations were integrated to obtain the blade section normal force. The present investigation evaluates the use of linear regression analysis and of neural networks in estimating the blade section normal force coefficient from a limited number of blade leading-edge pressure measurements and representative operating conditions. These network models are subsequently used to estimate the airloads at intermediate radial locations where only blade pressure measurements at the 3.5% chordwise stations are available.

Multimodal optical coherence tomography for in vivo imaging of brain tissue structure and microvascular network at glioblastoma

NASA Astrophysics Data System (ADS)

Yashin, Konstantin S.; Kiseleva, Elena B.; Gubarkova, Ekaterina V.; Matveev, Lev A.; Karabut, Maria M.; Elagin, Vadim V.; Sirotkina, Marina A.; Medyanik, Igor A.; Kravets, L. Y.; Gladkova, Natalia D.

2017-02-01

In the case of infiltrative brain tumors the surgeon faces difficulties in determining their boundaries to achieve total resection. The aim of the investigation was to evaluate the performance of multimodal OCT (MM OCT) for differential diagnostics of normal brain tissue and glioma using an experimental model of glioblastoma. The spectral domain OCT device that was used for the study provides simultaneously two modes: cross-polarization and microangiographic OCT. The comparative analysis of the both OCT modalities images from tumorous and normal brain tissue areas concurrently with histologic correlation shows certain difference between when accordingly to morphological and microvascular tissue features.

A normal mode-based geometric simulation approach for exploring biologically relevant conformational transitions in proteins.

PubMed

Ahmed, Aqeel; Rippmann, Friedrich; Barnickel, Gerhard; Gohlke, Holger

2011-07-25

A three-step approach for multiscale modeling of protein conformational changes is presented that incorporates information about preferred directions of protein motions into a geometric simulation algorithm. The first two steps are based on a rigid cluster normal-mode analysis (RCNMA). Low-frequency normal modes are used in the third step (NMSim) to extend the recently introduced idea of constrained geometric simulations of diffusive motions in proteins by biasing backbone motions of the protein, whereas side-chain motions are biased toward favorable rotamer states. The generated structures are iteratively corrected regarding steric clashes and stereochemical constraint violations. The approach allows performing three simulation types: unbiased exploration of conformational space; pathway generation by a targeted simulation; and radius of gyration-guided simulation. When applied to a data set of proteins with experimentally observed conformational changes, conformational variabilities are reproduced very well for 4 out of 5 proteins that show domain motions, with correlation coefficients r > 0.70 and as high as r = 0.92 in the case of adenylate kinase. In 7 out of 8 cases, NMSim simulations starting from unbound structures are able to sample conformations that are similar (root-mean-square deviation = 1.0-3.1 Å) to ligand bound conformations. An NMSim generated pathway of conformational change of adenylate kinase correctly describes the sequence of domain closing. The NMSim approach is a computationally efficient alternative to molecular dynamics simulations for conformational sampling of proteins. The generated conformations and pathways of conformational transitions can serve as input to docking approaches or as starting points for more sophisticated sampling techniques.

Evaluation of flaws in carbon steel piping. Final report

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

Zahoor, A.; Gamble, R.M.; Mehta, H.S.

1986-10-01

The objective of this program was to develop flaw evaluation procedures and allowable flaw sizes for ferritic piping used in light water reactor (LWR) power generation facilities. The program results provide relevant ASME Code groups with the information necessary to define flaw evaluation procedures, allowable flaw sizes, and their associated bases for Section XI of the code. Because there are several possible flaw-related failure modes for ferritic piping over the LWR operating temperature range, three analysis methods were employed to develop the evaluation procedures. These include limit load analysis for plastic collapse, elastic plastic fracture mechanics (EPFM) analysis for ductilemore » tearing, and linear elastic fracture mechanics (LEFM) analysis for non ductile crack extension. To ensure the appropriate analysis method is used in an evaluation, a step by step procedure also is provided to identify the relevant acceptance standard or procedure on a case by case basis. The tensile strength and toughness properties required to complete the flaw evaluation for any of the three analysis methods are included in the evaluation procedure. The flaw evaluation standards are provided in tabular form for the plastic collapse and ductile tearing modes, where the allowable part through flaw depth is defined as a function of load and flaw length. For non ductile crack extension, linear elastic fracture mechanics analysis methods, similar to those in Appendix A of Section XI, are defined. Evaluation flaw sizes and procedures are developed for both longitudinal and circumferential flaw orientations and normal/upset and emergency/faulted operating conditions. The tables are based on margins on load of 2.77 and 1.39 for circumferential flaws and 3.0 and 1.5 for longitudinal flaws for normal/upset and emergency/faulted conditions, respectively.« less

Large-amplitude hydromagnetic waves in collisionless relativistic plasma - Exact solution for the fast-mode magnetoacoustic wave

NASA Technical Reports Server (NTRS)

Barnes, A.

1983-01-01

An exact nonlinear solution is found to the relativistic kinetic and electrodynamic equations (in their hydromagnetic limit) that describes the large-amplitude fast-mode magnetoacoustic wave propagating normal to the magnetic field in a collisionless, previously uniform plasma. It is pointed out that a wave of this kind will be generated by transverse compression of any collisionless plasma. The solution is in essence independent of the detailed form of the particle momentum distribution functions. The solution is obtained, in part, through the method of characteristics; the wave exhibits the familiar properties of steepening and shock formation. A detailed analysis is given of the ultrarelativistic limit of this wave.

Blade loss transient dynamics analysis with flexible bladed disk

NASA Technical Reports Server (NTRS)

Gallardo, V. C.; Black, G.; Bach, L.; Cline, S.; Storace, A.

1983-01-01

The transient dynamic response of a flexible bladed disk on a flexible rotor in a two rotor system is formulated by modal synthesis and a Lagrangian approach. Only the nonequilibrated one diameter flexible mode is considered for the flexible bladed disk, while the two flexible rotors are represented by their normal modes. The flexible bladed disk motion is modeled as a combination of two one diameter standing waves, and is coupled inertially and gyroscopically to the flexible rotors. Application to a two rotor model shows that a flexible bladed disk on one rotor can be driven into resonance by an unbalance in the other rotor, and at a frequency equal to the difference in the rotor speeds.

Observations of the azimuthal dependence of normal mode coupling below 4 mHz at the South Pole and its nearby stations: Insights into the anisotropy beneath the Transantarctic Mountains

NASA Astrophysics Data System (ADS)

Hu, Xiao Gang

2016-08-01

Normal mode coupling pair 0S26-0T26 and 0S27-0T27 are significantly present at the South Pole station QSPA after the 2011/03/11 Mw9.1 Tohoku earthquake. In an attempt to determine the mechanisms responsible for the coupling pairs, I first investigate mode observations at 43 stations distributed along the polar great-circle path for the earthquake and observations at 32 Antarctic stations. I rule out the effect of Earth's rotation as well as the effect of global large-scale lateral heterogeneity, but argue instead for the effect of small-scale local azimuthal anisotropy in a depth extent about 300 km. The presence of quasi-Love waveform in 2-5 mHz at QSPA and its nearby stations confirms the predication. Secondly, I analyze normal mode observations at the South Pole location after 28 large earthquakes from 1998 to 2015. The result indicates that the presence of the mode coupling is azimuthal dependent, which is related to event azimuths in -46° to -18°. I also make a comparison between the shear-wave splitting measurements of previous studies and the mode coupling observations of this study, suggesting that their difference can be explained by a case that the anisotropy responsible for the mode coupling is not just below the South Pole location but located below region close to the Transantarctic Mountains (TAM). Furthermore, more signals of local azimuthal anisotropy in normal-mode observations at QSPA and SBA, such as coupling of 0S12-0T11 and vertical polarization anomaly for 0T10, confirms the existence of deep anisotropy close to TAM, which may be caused by asthenospheric mantle flow and edge convection around cratonic keel of TAM.

User's Manual for DuctE3D: A Program for 3D Euler Unsteady Aerodynamic and Aeroelastic Analysis of Ducted Fans

NASA Technical Reports Server (NTRS)

Srivastava, R.; Reddy, T. S. R.

1997-01-01

The program DuctE3D is used for steady or unsteady aerodynamic and aeroelastic analysis of ducted fans. This guide describes the input data required and the output files generated, in using DuctE3D. The analysis solves three dimensional unsteady, compressible Euler equations to obtain the aerodynamic forces. A normal mode structural analysis is used to obtain the aeroelastic equations, which are solved using either the time domain or the frequency domain solution method. Sample input and output files are included in this guide for steady aerodynamic analysis and aeroelastic analysis of an isolated fan row.

A practical method to avoid zero-point leak in molecular dynamics calculations: application to the water dimer.

PubMed

Czakó, Gábor; Kaledin, Alexey L; Bowman, Joel M

2010-04-28

We report the implementation of a previously suggested method to constrain a molecular system to have mode-specific vibrational energy greater than or equal to the zero-point energy in quasiclassical trajectory calculations [J. M. Bowman et al., J. Chem. Phys. 91, 2859 (1989); W. H. Miller et al., J. Chem. Phys. 91, 2863 (1989)]. The implementation is made practical by using a technique described recently [G. Czako and J. M. Bowman, J. Chem. Phys. 131, 244302 (2009)], where a normal-mode analysis is performed during the course of a trajectory and which gives only real-valued frequencies. The method is applied to the water dimer, where its effectiveness is shown by computing mode energies as a function of integration time. Radial distribution functions are also calculated using constrained quasiclassical and standard classical molecular dynamics at low temperature and at 300 K and compared to rigorous quantum path integral calculations.

Combined Analysis of Neutrino and Antineutrino Oscillations at T2K

NASA Astrophysics Data System (ADS)

Abe, K.; Amey, J.; Andreopoulos, C.; Antonova, M.; Aoki, S.; Ariga, A.; Autiero, D.; Ban, S.; Barbi, M.; Barker, G. J.; Barr, G.; Barry, C.; Bartet-Friburg, P.; Batkiewicz, M.; Berardi, V.; Berkman, S.; Bhadra, S.; Bienstock, S.; Blondel, A.; Bolognesi, S.; Bordoni, S.; Boyd, S. B.; Brailsford, D.; Bravar, A.; Bronner, C.; Buizza Avanzini, M.; Calland, R. G.; Campbell, T.; Cao, S.; Cartwright, S. L.; Catanesi, M. G.; Cervera, A.; Checchia, C.; Cherdack, D.; Chikuma, N.; Christodoulou, G.; Clifton, A.; Coleman, J.; Collazuol, G.; Coplowe, D.; Cudd, A.; Dabrowska, A.; De Rosa, G.; Dealtry, T.; Denner, P. F.; Dennis, S. R.; Densham, C.; Dewhurst, D.; Di Lodovico, F.; Di Luise, S.; Dolan, S.; Drapier, O.; Duffy, K. E.; Dumarchez, J.; Dziewiecki, M.; Emery-Schrenk, S.; Ereditato, A.; Feusels, T.; Finch, A. J.; Fiorentini, G. A.; Friend, M.; Fujii, Y.; Fukuda, D.; Fukuda, Y.; Galymov, V.; Garcia, A.; Giganti, C.; Gizzarelli, F.; Golan, T.; Gonin, M.; Hadley, D. R.; Haegel, L.; Haigh, M. D.; Hansen, D.; Harada, J.; Hartz, M.; Hasegawa, T.; Hastings, N. C.; Hayashino, T.; Hayato, Y.; Helmer, R. L.; Hillairet, A.; Hiraki, T.; Hiramoto, A.; Hirota, S.; Hogan, M.; Holeczek, J.; Hosomi, F.; Huang, K.; Ichikawa, A. K.; Ikeda, M.; Imber, J.; Insler, J.; Intonti, R. A.; Ishida, T.; Ishii, T.; Iwai, E.; Iwamoto, K.; Izmaylov, A.; Jamieson, B.; Jiang, M.; Johnson, S.; Jonsson, P.; Jung, C. K.; Kabirnezhad, M.; Kaboth, A. C.; Kajita, T.; Kakuno, H.; Kameda, J.; Karlen, D.; Katori, T.; Kearns, E.; Khabibullin, M.; Khotjantsev, A.; Kim, H.; Kim, J.; King, S.; Kisiel, J.; Knight, A.; Knox, A.; Kobayashi, T.; Koch, L.; Koga, T.; Konaka, A.; Kondo, K.; Kormos, L. L.; Korzenev, A.; Koshio, Y.; Kowalik, K.; Kropp, W.; Kudenko, Y.; Kurjata, R.; Kutter, T.; Lagoda, J.; Lamont, I.; Lamoureux, M.; Larkin, E.; Lasorak, P.; Laveder, M.; Lawe, M.; Licciardi, M.; Lindner, T.; Liptak, Z. J.; Litchfield, R. P.; Li, X.; Longhin, A.; Lopez, J. P.; Lou, T.; Ludovici, L.; Lu, X.; Magaletti, L.; Mahn, K.; Malek, M.; Manly, S.; Marino, A. D.; Martin, J. F.; Martins, P.; Martynenko, S.; Maruyama, T.; Matveev, V.; Mavrokoridis, K.; Ma, W. Y.; Mazzucato, E.; McCarthy, M.; McCauley, N.; McFarland, K. S.; McGrew, C.; Mefodiev, A.; Metelko, C.; Mezzetto, M.; Mijakowski, P.; Minamino, A.; Mineev, O.; Mine, S.; Missert, A.; Miura, M.; Moriyama, S.; Mueller, Th. A.; Myslik, J.; Nakadaira, T.; Nakahata, M.; Nakamura, K. G.; Nakamura, K.; Nakamura, K. D.; Nakanishi, Y.; Nakayama, S.; Nakaya, T.; Nakayoshi, K.; Nantais, C.; Nielsen, C.; Nirkko, M.; Nishikawa, K.; Nishimura, Y.; Novella, P.; Nowak, J.; O'Keeffe, H. M.; Okumura, K.; Okusawa, T.; Oryszczak, W.; Oser, S. M.; Ovsyannikova, T.; Owen, R. A.; Oyama, Y.; Palladino, V.; Palomino, J. L.; Paolone, V.; Patel, N. D.; Paudyal, P.; Pavin, M.; Payne, D.; Perkin, J. D.; Petrov, Y.; Pickard, L.; Pickering, L.; Pinzon Guerra, E. S.; Pistillo, C.; Popov, B.; Posiadala-Zezula, M.; Poutissou, J.-M.; Poutissou, R.; Przewlocki, P.; Quilain, B.; Radermacher, T.; Radicioni, E.; Ratoff, P. N.; Ravonel, M.; Rayner, M. A.; Redij, A.; Reinherz-Aronis, E.; Riccio, C.; Rodrigues, P. A.; Rondio, E.; Rossi, B.; Roth, S.; Rubbia, A.; Rychter, A.; Sakashita, K.; Sánchez, F.; Scantamburlo, E.; Scholberg, K.; Schwehr, J.; Scott, M.; Seiya, Y.; Sekiguchi, T.; Sekiya, H.; Sgalaberna, D.; Shah, R.; Shaikhiev, A.; Shaker, F.; Shaw, D.; Shiozawa, M.; Shirahige, T.; Short, S.; Smy, M.; Sobczyk, J. T.; Sobel, H.; Sorel, M.; Southwell, L.; Steinmann, J.; Stewart, T.; Stowell, P.; Suda, Y.; Suvorov, S.; Suzuki, A.; Suzuki, S. Y.; Suzuki, Y.; Tacik, R.; Tada, M.; Takeda, A.; Takeuchi, Y.; Tanaka, H. K.; Tanaka, H. A.; Terhorst, D.; Terri, R.; Thakore, T.; Thompson, L. F.; Tobayama, S.; Toki, W.; Tomura, T.; Touramanis, C.; Tsukamoto, T.; Tzanov, M.; Uchida, Y.; Vagins, M.; Vallari, Z.; Vasseur, G.; Vladisavljevic, T.; Wachala, T.; Walter, C. W.; Wark, D.; Wascko, M. O.; Weber, A.; Wendell, R.; Wilkes, R. J.; Wilking, M. J.; Wilkinson, C.; Wilson, J. R.; Wilson, R. J.; Wret, C.; Yamada, Y.; Yamamoto, K.; Yamamoto, M.; Yanagisawa, C.; Yano, T.; Yen, S.; Yershov, N.; Yokoyama, M.; Yoshida, K.; Yuan, T.; Yu, M.; Zalewska, A.; Zalipska, J.; Zambelli, L.; Zaremba, K.; Ziembicki, M.; Zimmerman, E. D.; Zito, M.; Żmuda, J.; T2K Collaboration

2017-04-01

T2K reports its first results in the search for C P violation in neutrino oscillations using appearance and disappearance channels for neutrino- and antineutrino-mode beams. The data include all runs from January 2010 to May 2016 and comprise 7.482 ×1 020 protons on target in neutrino mode, which yielded in the far detector 32 e -like and 135 μ -like events, and 7.471 ×1 020 protons on target in antineutrino mode, which yielded 4 e -like and 66 μ -like events. Reactor measurements of sin22 θ13 have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase δC P spans the range (-3.13 , -0.39 ) for normal mass ordering. The C P conservation hypothesis (δC P=0 , π ) is excluded at 90% C.L.

Combined Analysis of Neutrino and Antineutrino Oscillations at T2K.

PubMed

Abe, K; Amey, J; Andreopoulos, C; Antonova, M; Aoki, S; Ariga, A; Autiero, D; Ban, S; Barbi, M; Barker, G J; Barr, G; Barry, C; Bartet-Friburg, P; Batkiewicz, M; Berardi, V; Berkman, S; Bhadra, S; Bienstock, S; Blondel, A; Bolognesi, S; Bordoni, S; Boyd, S B; Brailsford, D; Bravar, A; Bronner, C; Buizza Avanzini, M; Calland, R G; Campbell, T; Cao, S; Cartwright, S L; Catanesi, M G; Cervera, A; Checchia, C; Cherdack, D; Chikuma, N; Christodoulou, G; Clifton, A; Coleman, J; Collazuol, G; Coplowe, D; Cudd, A; Dabrowska, A; De Rosa, G; Dealtry, T; Denner, P F; Dennis, S R; Densham, C; Dewhurst, D; Di Lodovico, F; Di Luise, S; Dolan, S; Drapier, O; Duffy, K E; Dumarchez, J; Dziewiecki, M; Emery-Schrenk, S; Ereditato, A; Feusels, T; Finch, A J; Fiorentini, G A; Friend, M; Fujii, Y; Fukuda, D; Fukuda, Y; Galymov, V; Garcia, A; Giganti, C; Gizzarelli, F; Golan, T; Gonin, M; Hadley, D R; Haegel, L; Haigh, M D; Hansen, D; Harada, J; Hartz, M; Hasegawa, T; Hastings, N C; Hayashino, T; Hayato, Y; Helmer, R L; Hillairet, A; Hiraki, T; Hiramoto, A; Hirota, S; Hogan, M; Holeczek, J; Hosomi, F; Huang, K; Ichikawa, A K; Ikeda, M; Imber, J; Insler, J; Intonti, R A; Ishida, T; Ishii, T; Iwai, E; Iwamoto, K; Izmaylov, A; Jamieson, B; Jiang, M; Johnson, S; Jonsson, P; Jung, C K; Kabirnezhad, M; Kaboth, A C; Kajita, T; Kakuno, H; Kameda, J; Karlen, D; Katori, T; Kearns, E; Khabibullin, M; Khotjantsev, A; Kim, H; Kim, J; King, S; Kisiel, J; Knight, A; Knox, A; Kobayashi, T; Koch, L; Koga, T; Konaka, A; Kondo, K; Kormos, L L; Korzenev, A; Koshio, Y; Kowalik, K; Kropp, W; Kudenko, Y; Kurjata, R; Kutter, T; Lagoda, J; Lamont, I; Lamoureux, M; Larkin, E; Lasorak, P; Laveder, M; Lawe, M; Licciardi, M; Lindner, T; Liptak, Z J; Litchfield, R P; Li, X; Longhin, A; Lopez, J P; Lou, T; Ludovici, L; Lu, X; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Martin, J F; Martins, P; Martynenko, S; Maruyama, T; Matveev, V; Mavrokoridis, K; Ma, W Y; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Mefodiev, A; Metelko, C; Mezzetto, M; Mijakowski, P; Minamino, A; Mineev, O; Mine, S; Missert, A; Miura, M; Moriyama, S; Mueller, Th A; Myslik, J; Nakadaira, T; Nakahata, M; Nakamura, K G; Nakamura, K; Nakamura, K D; Nakanishi, Y; Nakayama, S; Nakaya, T; Nakayoshi, K; Nantais, C; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; Novella, P; Nowak, J; O'Keeffe, H M; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Ovsyannikova, T; Owen, R A; Oyama, Y; Palladino, V; Palomino, J L; Paolone, V; Patel, N D; Paudyal, P; Pavin, M; Payne, D; Perkin, J D; Petrov, Y; Pickard, L; Pickering, L; Pinzon Guerra, E S; Pistillo, C; Popov, B; Posiadala-Zezula, M; Poutissou, J-M; Poutissou, R; Przewlocki, P; Quilain, B; Radermacher, T; Radicioni, E; Ratoff, P N; Ravonel, M; Rayner, M A; Redij, A; Reinherz-Aronis, E; Riccio, C; Rodrigues, P A; Rondio, E; Rossi, B; Roth, S; Rubbia, A; Rychter, A; Sakashita, K; Sánchez, F; Scantamburlo, E; Scholberg, K; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shah, R; Shaikhiev, A; Shaker, F; Shaw, D; Shiozawa, M; Shirahige, T; Short, S; Smy, M; Sobczyk, J T; Sobel, H; Sorel, M; Southwell, L; Steinmann, J; Stewart, T; Stowell, P; Suda, Y; Suvorov, S; Suzuki, A; Suzuki, S Y; Suzuki, Y; Tacik, R; Tada, M; Takeda, A; Takeuchi, Y; Tanaka, H K; Tanaka, H A; Terhorst, D; Terri, R; Thakore, T; Thompson, L F; Tobayama, S; Toki, W; Tomura, T; Touramanis, C; Tsukamoto, T; Tzanov, M; Uchida, Y; Vagins, M; Vallari, Z; Vasseur, G; Vladisavljevic, T; Wachala, T; Walter, C W; Wark, D; Wascko, M O; Weber, A; Wendell, R; Wilkes, R J; Wilking, M J; Wilkinson, C; Wilson, J R; Wilson, R J; Wret, C; Yamada, Y; Yamamoto, K; Yamamoto, M; Yanagisawa, C; Yano, T; Yen, S; Yershov, N; Yokoyama, M; Yoshida, K; Yuan, T; Yu, M; Zalewska, A; Zalipska, J; Zambelli, L; Zaremba, K; Ziembicki, M; Zimmerman, E D; Zito, M; Żmuda, J

2017-04-14

T2K reports its first results in the search for CP violation in neutrino oscillations using appearance and disappearance channels for neutrino- and antineutrino-mode beams. The data include all runs from January 2010 to May 2016 and comprise 7.482×10^{20} protons on target in neutrino mode, which yielded in the far detector 32 e-like and 135  μ-like events, and 7.471×10^{20} protons on target in antineutrino mode, which yielded 4 e-like and 66  μ-like events. Reactor measurements of sin^{2}2θ_{13} have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase δ_{CP} spans the range (-3.13, -0.39) for normal mass ordering. The CP conservation hypothesis (δ_{CP}=0, π) is excluded at 90% C.L.

The automated multi-stage substructuring system for NASTRAN

NASA Technical Reports Server (NTRS)

Field, E. I.; Herting, D. N.; Herendeen, D. L.; Hoesly, R. L.

1975-01-01

The substructuring capability developed for eventual installation in Level 16 is now operational in a test version of NASTRAN. Its features are summarized. These include the user-oriented, Case Control type control language, the automated multi-stage matrix processing, the independent direct access data storage facilities, and the static and normal modes solution capabilities. A complete problem analysis sequence is presented with card-by-card description of the user input.

Vibrational Spectral Studies of Gemfibrozil

NASA Astrophysics Data System (ADS)

Benitta, T. Asenath; Balendiran, G. K.; James, C.

2008-11-01

The Fourier Transform Raman and infrared spectra of the crystallized drug molecule 5-(2,5-Dimethylphenoxy)-2,2-dimethylpentanoic acid (Gemfibrozil) have been recorded and analyzed. Quantum chemical computational methods have been employed using Gaussian 03 software package based on Hartree Fock method for theoretically modeling the grown molecule. The optimized geometry and vibrational frequencies have been predicted. Observed vibrational modes have been assigned with the aid of normal coordinate analysis.

A test of the Hall-MHD model: Application to low-frequency upstream waves at Venus

NASA Technical Reports Server (NTRS)

Orlowski, D. S.; Russell, C. T.; Krauss-Varban, D.; Omidi, N.

1994-01-01

Early studies suggested that in the range of parameter space where the wave angular frequency is less than the proton gyrofrequency and the plasma beta, the ratio of the thermal to magnetic pressure, is less than 1 magnetohydrodynamics provides an adequate description of the propagating modes in a plasma. However, recently, Lacombe et al. (1992) have reported significant differences between basic wave characteristics of the specific propagation modes derived from linear Vlasov and Hall-magnetohydrodynamic (MHD) theories even when the waves are only weakly damped. In this paper we compare the magnetic polarization and normalization magnetic compression ratio of ultra low frequency (ULF) upstream waves at Venus with magnetic polarization and normalized magnetic compression ratio derived from both theories. We find that while the 'kinetic' approach gives magnetic polarization and normalized magnetic compression ratio consistent with the data in the analyzed range of beta (0.5 less than beta less than 5) for the fast magnetosonic mode, the same wave characteristics derived from the Hall-MHD model strongly depend on beta and are consistent with the data only at low beta for the fast mode and at high beta for the intermediate mode.

Whole-Lesion Histogram Analysis of Apparent Diffusion Coefficient for the Assessment of Cervical Cancer.

PubMed

Guan, Yue; Shi, Hua; Chen, Ying; Liu, Song; Li, Weifeng; Jiang, Zhuoran; Wang, Huanhuan; He, Jian; Zhou, Zhengyang; Ge, Yun

2016-01-01

The aim of this study was to explore the application of whole-lesion histogram analysis of apparent diffusion coefficient (ADC) values of cervical cancer. A total of 54 women (mean age, 53 years) with cervical cancers underwent 3-T diffusion-weighted imaging with b values of 0 and 800 s/mm prospectively. Whole-lesion histogram analysis of ADC values was performed. Paired sample t test was used to compare differences in ADC histogram parameters between cervical cancers and normal cervical tissues. Receiver operating characteristic curves were constructed to identify the optimal threshold of each parameter. All histogram parameters in this study including ADCmean, ADCmin, ADC10%-ADC90%, mode, skewness, and kurtosis of cervical cancers were significantly lower than those of normal cervical tissues (all P < 0.0001). ADC90% had the largest area under receiver operating characteristic curve of 0.996. Whole-lesion histogram analysis of ADC maps is useful in the assessment of cervical cancer.

Near- and far-field investigation of dark and bright higher order resonances in square loop elements at mid-infrared wavelengths.

PubMed

Tucker, Eric; D'Archangel, Jeffrey; Boreman, Glenn

2017-03-06

Three different size gold square loop structures were fabricated as arrays on ZnS over a ground plane and designed to have absorptive fundamental, second order, and third order resonances at a wavelength of 10.6 µm and 60° off-normal. The angular dependent far-field spectral absorptivity was investigated over the mid-infrared for each size loop array. It was found that the second order modes were dark at normal incidence, but became excited at off-normal incidence, which is consistent with previous work for similar geometry structures. Furthermore, near-field measurements and simulations at a wavelength of 10.6 µm and 60° off-normal showed that the second order mode (quadrupolar) of the medium size loop yielded a near-field response similar in magnitude to the fundamental mode (dipolar) of the small size loop, which can be important for sensing related applications where both strong near-field enhancement and more uniform or less localized field is beneficial.

Stress analysis of rotating propellers subject to forced excitations

NASA Astrophysics Data System (ADS)

Akgun, Ulas

Turbine blades experience vibrations due to the flow disturbances. These vibrations are the leading cause for fatigue failure in turbine blades. This thesis presents the finite element analysis methods to estimate the maximum vibrational stresses of rotating structures under forced excitation. The presentation included starts with the derived equations of motion for vibration of rotating beams using energy methods under the Euler Bernoulli beam assumptions. The nonlinear large displacement formulation captures the centrifugal stiffening and gyroscopic effects. The weak form of the equations and their finite element discretization are shown. The methods implemented were used for normal modes analyses and forced vibration analyses of rotating beam structures. The prediction of peak stresses under simultaneous multi-mode excitation show that the maximum vibrational stresses estimated using the linear superposition of the stresses can greatly overestimate the stresses if the phase information due to damping (physical and gyroscopic effects) are neglected. The last section of this thesis also presents the results of a practical study that involves finite element analysis and redesign of a composite propeller.

Analysis of wind-driven ambient noise in a shallow water environment with a sandy seabed.

PubMed

Knobles, D P; Joshi, S M; Gaul, R D; Graber, H C; Williams, N J

2008-09-01

On the New Jersey continental shelf ambient sound levels were recorded during tropical storm Ernesto that produced wind speeds up to 40 knots in early September 2006. The seabed at the position of the acoustic measurements can be approximately described as coarse sand. Differences between the ambient noise levels for the New Jersey shelf measurements and deep water reference measurements are modeled using both normal mode and ray methods. The analysis is consistent with a nonlinear frequency dependent seabed attenuation for the New Jersey site.

Jeans instability of magnetized quantum plasma: Effect of viscosity, rotation and finite Larmor radius corrections

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

Jain, Shweta, E-mail: jshweta09@gmail.com; Sharma, Prerana; Chhajlani, R. K.

2015-07-31

The Jeans instability of self-gravitating quantum plasma is examined considering the effects of viscosity, finite Larmor radius (FLR) corrections and rotation. The analysis is done by normal mode analysis theory with the help of relevant linearized perturbation equations of the problem. The general dispersion relation is obtained using the quantum magneto hydrodynamic model. The modified condition of Jeans instability is obtained and the numerical calculations have been performed to show the effects of various parameters on the growth rate of Jeans instability.

Task Analytic Models to Guide Analysis and Design: Use of the Operator Function Model to Represent Pilot-Autoflight System Mode Problems

NASA Technical Reports Server (NTRS)

Degani, Asaf; Mitchell, Christine M.; Chappell, Alan R.; Shafto, Mike (Technical Monitor)

1995-01-01

Task-analytic models structure essential information about operator interaction with complex systems, in this case pilot interaction with the autoflight system. Such models serve two purposes: (1) they allow researchers and practitioners to understand pilots' actions; and (2) they provide a compact, computational representation needed to design 'intelligent' aids, e.g., displays, assistants, and training systems. This paper demonstrates the use of the operator function model to trace the process of mode engagements while a pilot is controlling an aircraft via the, autoflight system. The operator function model is a normative and nondeterministic model of how a well-trained, well-motivated operator manages multiple concurrent activities for effective real-time control. For each function, the model links the pilot's actions with the required information. Using the operator function model, this paper describes several mode engagement scenarios. These scenarios were observed and documented during a field study that focused on mode engagements and mode transitions during normal line operations. Data including time, ATC clearances, altitude, system states, and active modes and sub-modes, engagement of modes, were recorded during sixty-six flights. Using these data, seven prototypical mode engagement scenarios were extracted. One scenario details the decision of the crew to disengage a fully automatic mode in favor of a semi-automatic mode, and the consequences of this action. Another describes a mode error involving updating aircraft speed following the engagement of a speed submode. Other scenarios detail mode confusion at various phases of the flight. This analysis uses the operator function model to identify three aspects of mode engagement: (1) the progress of pilot-aircraft-autoflight system interaction; (2) control/display information required to perform mode management activities; and (3) the potential cause(s) of mode confusion. The goal of this paper is twofold: (1) to demonstrate the use of the operator functio model methodology to describe pilot-system interaction while engaging modes And monitoring the system, and (2) to initiate a discussion of how task-analytic models might inform design processes. While the operator function model is only one type of task-analytic representation, the hypothesis of this paper is that some type of task analytic structure is a prerequisite for the design of effective human-automation interaction.

Nonlinear Pressurization and Modal Analysis Procedure for Dynamic Modeling of Inflatable Structures

NASA Technical Reports Server (NTRS)

Smalley, Kurt B.; Tinker, Michael L.; Saxon, Jeff (Technical Monitor)

2002-01-01

An introduction and set of guidelines for finite element dynamic modeling of nonrigidized inflatable structures is provided. A two-step approach is presented, involving 1) nonlinear static pressurization of the structure and updating of the stiffness matrix and 2) hear normal modes analysis using the updated stiffness. Advantages of this approach are that it provides physical realism in modeling of pressure stiffening, and it maintains the analytical convenience of a standard bear eigensolution once the stiffness has been modified. Demonstration of the approach is accomplished through the creation and test verification of an inflated cylinder model using a large commercial finite element code. Good frequency and mode shape comparisons are obtained with test data and previous modeling efforts, verifying the accuracy of the technique. Problems encountered in the application of the approach, as well as their solutions, are discussed in detail.

Understanding the connection between conformational changes of peptides and equilibrium thermal fluctuations.

PubMed

Soler, Miguel A; Zúñiga, José; Requena, Alberto; Bastida, Adolfo

2017-02-01

Despite the increasing evidence that conformational transitions in peptides and proteins are driven by specific vibrational energy pathways along the molecule, the current experimental techniques of analysis do as yet not allow to study these biophysical processes in terms of anisotropic energy flows. Computational methods offer a complementary approach to obtain a more detailed understanding of the vibrational and conformational dynamics of these systems. Accordingly, in this work we investigate jointly the vibrational energy distribution and the conformational dynamics of trialanine peptide in water solution at room temperature by applying the Instantaneous Normal Mode analysis to the results derived from equilibrium molecular dynamics simulations. It is shown that conformational changes in trialanine are triggered by the vibrational energy accumulated in the low-frequency modes of the molecule, and that excitation is caused exclusively by thermal fluctuations of the solute-solvent system, thus excluding the possibility of an intramolecular vibrational energy redistribution process.

A new approach to the linear theory of single-species tearing in two-dimensional quasi-neutral sheets

NASA Technical Reports Server (NTRS)

Brittnacher, M.; Quest, K. B.; Karimabadi, H.

1995-01-01

We have developed the linear theory of collisionless ion tearing in a two-dimensional magnetotail equilibrium for a single resonant species. We have solved the normal mode problem for tearing instability by an algorithm that employs particle-in-cell simulation to calculate the orbit integrals in the Maxwell-Vlasov eigenmode equation. The results of our single-species tearing analysis can be applied to ion tearing where electron effects are not included. We have calculated the tearing growth rate as a function of the magnetic field component B(sub n) normal to the current sheet for thick and thin current sheets, and we show that marginal stability occurs when the normal gyrofrequency Omega(sub n) is comparable to the Harris neutral sheet growth rate. A cross-tail B(sub y) component has little effect on the growth rate for B(sub y) approximately = B(sub n). Even in the limit B(sub y) much greater than B(sub n), the mode is strongly stabilized by B(sub n). We report than random pitch angle scattering can overcome the stabilizing effect of B(sub n) and drive the growth rate up toward the Harris neutral sheet (B(sub n) = 0) value when the pitch angle diffusion rate is comparable to Omega(sub n).

Correlation of finite element free vibration predictions using random vibration test data. M.S. Thesis - Cleveland State Univ.

NASA Technical Reports Server (NTRS)

Chambers, Jeffrey A.

1994-01-01

Finite element analysis is regularly used during the engineering cycle of mechanical systems to predict the response to static, thermal, and dynamic loads. The finite element model (FEM) used to represent the system is often correlated with physical test results to determine the validity of analytical results provided. Results from dynamic testing provide one means for performing this correlation. One of the most common methods of measuring accuracy is by classical modal testing, whereby vibratory mode shapes are compared to mode shapes provided by finite element analysis. The degree of correlation between the test and analytical mode shapes can be shown mathematically using the cross orthogonality check. A great deal of time and effort can be exhausted in generating the set of test acquired mode shapes needed for the cross orthogonality check. In most situations response data from vibration tests are digitally processed to generate the mode shapes from a combination of modal parameters, forcing functions, and recorded response data. An alternate method is proposed in which the same correlation of analytical and test acquired mode shapes can be achieved without conducting the modal survey. Instead a procedure is detailed in which a minimum of test information, specifically the acceleration response data from a random vibration test, is used to generate a set of equivalent local accelerations to be applied to the reduced analytical model at discrete points corresponding to the test measurement locations. The static solution of the analytical model then produces a set of deformations that once normalized can be used to represent the test acquired mode shapes in the cross orthogonality relation. The method proposed has been shown to provide accurate results for both a simple analytical model as well as a complex space flight structure.

Quantitative analysis of pulmonary pathophysiology using postmortem computed tomography with regard to the cause of death.

PubMed

Michiue, Tomomi; Sakurai, Terumi; Ishikawa, Takaki; Oritani, Shigeki; Maeda, Hitoshi

2012-07-10

Radiological lung transparency depends on the air contents involved in respiratory function. The present study quantitatively investigated postmortem lung air distribution in forensic autopsy cases (n=135) using computed tomography (CT) to analyze cardiopulmonary pathophysiology in the death process, involving emphysema, congestion and edema. Combined analyses of the CT morphology and attenuation value (Hounsfield unit, HU) of the bilateral lungs, with reference to histopathology, could categorize CT findings (10-90 percentile mode/mean HU values) with regard to the causes of death as follows: (I) hyperaeration (mode/mean HU below -760/-560: emphysema) for obstructive pulmonary disease, starvation and hypothermia (cold exposure); (II) mostly normal aeration with partial ground glass opacification (mode/mean HU, -850 to -360/-700 to -380: partial congestion and edema), consisting of subtype II-a with peri-bronchial/-vascular opacity for mechanical asphyxia, drowning and fire fatality, and subtype II-b with decreased vascularity for gunshot head injury, cerebrovascular disease and hemopericardium; (III) hypoaeration to airless with predominant hypostatic ground glass opacification (mode/mean HU, -870 to 0/-720 to -200: mottled hypostatic congestion and edema) for blunt head/neck injury, intoxication, hyperthermia (heat stroke) and congestive heart failure; (IV) hypoaeration to airless with predominant hypostatic consolidation (mode/mean HU, -790 to 0/-520 to -70: intense hypostatic congestion with edema) for acute ischemic heart disease; and (V) airless to consolidated (mode/mean HU over -420/-370: segmental or multiple patchy consolidations with edema) for pneumonia. Mode HU represents the major alveolar status, while the mean HU reflects the whole lung air contents. CT data analysis is useful for quantitative evaluation of pulmonary pathology as a supplementary procedure. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Evaluation of diaphragmatic motion in normal and diaphragmatic paralyzed dogs using M-mode ultrasonography.

PubMed

Choi, Mihyun; Lee, Namsoon; Kim, Ahyoung; Keh, Seoyeon; Lee, Jinsoo; Kim, Hyunwook; Choi, Mincheol

2014-01-01

Diagnosis of unilateral diaphragmatic paralysis in dogs is currently based on fluoroscopic detection of unequal movement between the crura. Bilateral paralysis may be more difficult to confirm with fluoroscopy because diaphragmatic movement is sometimes produced by compensatory abdominal muscle contractions. The purpose of this study was to develop a new method to evaluate diaphragmatic movement using M-mode ultrasonography and to describe findings for normal and diaphragmatic paralyzed dogs. Fifty-five clinically normal dogs and two dogs with diaphragmatic paralysis were recruited. Thoracic radiographs were acquired for all dogs and fluoroscopy studies were also acquired for clinically affected dogs. Two observers independently measured diaphragmatic direction of motion and amplitude of excursion using M-mode ultrasonography for dogs meeting study inclusion criteria. Eight of the clinically normal dogs were excluded due to abnormal thoracic radiographic findings. For the remaining normal dogs, the lower limit values of diaphragmatic excursion were 2.85-2.98 mm during normal breathing. One dog with bilateral diaphragmatic paralysis showed paradoxical movement of both crura at the end of inspiration. One dog with unilateral diaphragmatic paralysis had diaphragmatic excursion values of 2.00 ± 0.42 mm on the left side and 4.05 ± 1.48 mm on the right side. The difference between left and right diaphragmatic excursion values was 55%. Findings indicated that M-mode ultrasonography is a relatively simple and objective method for measuring diaphragmatic movement in dogs. Future studies are needed in a larger number of dogs with diaphragmatic paralysis to determine the diagnostic sensitivity of this promising new technique. © 2013 American College of Veterinary Radiology.

Evaluating the 'Focus on Normal Birth and Reducing Caesarean section Rates Rapid Improvement Programme': A mixed method study in England.

PubMed

Marshall, Joyce L; Spiby, Helen; McCormick, Felicia

2015-02-01

caesarean section plays an important role in ensuring safety of mother and infant but rising rates are not accompanied by measurable improvements in maternal or neonatal mortality or morbidity. The 'Focus on Normal Birth and Reducing Caesarean section Rates Rapid Improvement Programme' was a facilitative initiative developed to promote opportunities for normal birth and reduce caesarean section rates in England. to evaluate the 'Focus on Normal Birth and Reducing Caesarean section Rates' programme, by assessment of: impact on caesarean section rates, use of service improvements tools and participants׳ perceptions of factors that sustain or hinder work within participating maternity units. a mixed methods approach included analysis of mode of birth data, web-based questionnaires and in-depth semi-structured telephone interviews. twenty Hospital Trusts in England (selected from 68 who applied) took part in the 'Focus on Normal Birth and Reducing Caesarean section Rates Rapid Improvement Programme' initiative. In each hospital Trust, the head of midwifery, an obstetrician, the relevant lead for organisational development, a supervisor of midwives, or a clinical midwife and a service user representative were invited to participate in the independent evaluation. collection and analysis of mode of birth data from 20 participating hospital Trusts, web-based questionnaires administered to key individuals in all 20 Trusts and in-depth semi-structured telephone interviews conducted with key individuals in a sample of six Trusts. there was a marginal decline of 0.5% (25.9% from 26.4%) in mean total caesarean section rate in the period 1 January 2009 to 31 January 2010 compared to the baseline period (1 July-31 December 2008). Reduced total caesarean section rates were achieved in eight trusts, all with higher rates at the beginning of the initiative. Features associated with lower caesarean section rates included a shared philosophy prioritising normal birth, clear communication across disciplines and strong leadership at a range of levels, including executive support and clinical leaders within each discipline. it is important that the philosophy and organisational context of care are examined to identify potential barriers and facilitative factors. Copyright © 2014 Elsevier Ltd. All rights reserved.

A reference equation for maximal aerobic power for treadmill and cycle ergometer exercise testing: Analysis from the FRIEND registry.

PubMed

de Souza E Silva, Christina G; Kaminsky, Leonard A; Arena, Ross; Christle, Jeffrey W; Araújo, Claudio Gil S; Lima, Ricardo M; Ashley, Euan A; Myers, Jonathan

2018-05-01

Background Maximal oxygen uptake (VO 2 max) is a powerful predictor of health outcomes. Valid and portable reference values are integral to interpreting measured VO 2 max; however, available reference standards lack validation and are specific to exercise mode. This study was undertaken to develop and validate a single equation for normal standards for VO 2 max for the treadmill or cycle ergometer in men and women. Methods Healthy individuals ( N = 10,881; 67.8% men, 20-85 years) who performed a maximal cardiopulmonary exercise test on either a treadmill or a cycle ergometer were studied. Of these, 7617 and 3264 individuals were randomly selected for development and validation of the equation, respectively. A Brazilian sample (1619 individuals) constituted a second validation cohort. The prediction equation was determined using multiple regression analysis, and comparisons were made with the widely-used Wasserman and European equations. Results Age, sex, weight, height and exercise mode were significant predictors of VO 2 max. The regression equation was: VO 2 max (ml kg -1  min -1 ) = 45.2 - 0.35*Age - 10.9*Sex (male = 1; female = 2) - 0.15*Weight (pounds) + 0.68*Height (inches) - 0.46*Exercise Mode (treadmill = 1; bike = 2) ( R = 0.79, R 2  = 0.62, standard error of the estimate = 6.6 ml kg -1  min -1 ). Percentage predicted VO 2 max for the US and Brazilian validation cohorts were 102.8% and 95.8%, respectively. The new equation performed better than traditional equations, particularly among women and individuals ≥60 years old. Conclusion A combined equation was developed for normal standards for VO 2 max for different exercise modes derived from a US national registry. The equation provided a lower average error between measured and predicted VO 2 max than traditional equations even when applied to an independent cohort. Additional studies are needed to determine its portability.

Influence of Stationary Crossflow Modulation on Secondary Instability

NASA Technical Reports Server (NTRS)

Choudhari, Meelan M.; Li, Fei; Paredes, Pedro

2016-01-01

A likely scenario for swept wing transition on subsonic aircraft with natural laminar flow involves the breakdown of stationary crossflow vortices via high frequency secondary instability. A majority of the prior research on this secondary instability has focused on crossflow vortices with a single dominant spanwise wavelength. This paper investigates the effects of the spanwise modulation of stationary crossflow vortices at a specified wavelength by a subharmonic stationary mode. Secondary instability of the modulated crossflow pattern is studied using planar, partial-differential-equation based eigenvalue analysis. Computations reveal that weak modulation by the first subharmonic of the input stationary mode leads to mode splitting that is particularly obvious for Y-type secondary modes that are driven by the wall-normal shear of the basic state. Thus, for each Y mode corresponding to the fundamental wavelength of results in unmodulated train of crossflow vortices, the modulated flow supports a pair of secondary modes with somewhat different amplification rates. The mode splitting phenomenon suggests that a more complex stationary modulation such as that induced by natural surface roughness would yield a considerably richer spectrum of secondary instability modes. Even modest levels of subharmonic modulation are shown to have a strong effect on the overall amplification of secondary disturbances, particularly the Z-modes driven by the spanwise shear of the basic state. Preliminary computations related to the nonlinear breakdown of these secondary disturbances provide interesting insights into the process of crossflow transition in the presence of the first subharmonic of the dominant stationary vortex.

Synthesis, characterization, vibrational spectroscopy, and factor group analysis of partially metal-doped phosphate materials

NASA Astrophysics Data System (ADS)

Sronsri, Chuchai; Boonchom, Banjong

2018-04-01

A simple precipitating method was used to synthesize effectively a partially metal-doped phosphate hydrate (Mn0.9Mg0.1HPO4·3H2O), whereas the thermal decomposition process of the above hydrate precursor was used to obtain Mn1.8Mg0.2P2O7 and LiMn0.9Mg0.1PO4 compounds under different conditions. To separate the overlapping thermal decomposition peak, a deconvolution technique was used, and the separated peak was applied to calculate the water content. The factor group splitting analysis was used to exemplify their vibrational spectra obtained from normal vibrations of HPO42-, H2O, P2O74- and PO43- functional groups. Further, the deconvoluted bending mode of water was clearly observed. Mn0.9Mg0.1HPO4·3H2O was observed in the orthorhombic crystal system with the space group of Pbca (D2h15). The formula units per unit cell were found to be eight (Z = 8), and the site symmetric type of HPO42- was observed as Cs. For the HPO42- unit, the correlation filed splitting analysis of type C3v - Cs - D2h15 was calculated and had 96 internal modes, whereas H2O in the above hydrate was symbolized as C2v - Cs - D2h15 and had 24 modes. The symbol C2v - Cs - C2h3 was used for the correlation filed splitting analysis of P2O74- in Mn1.8Mg0.2P2O7 (monoclinic, C2/m (C2h3), Z = 2, and 42 modes). Finally, the symbol Td - Cs - D2h16 was used for the correlation filed splitting analysis of PO43- in LiMn0.9Mg0.1PO4 (orthorhombic, Pnma (D2h16), Z = 4, and 36 modes).

Biomechanical measurements of stiffness and strength for five types of whole human and artificial humeri.

PubMed

Aziz, Mina S R; Nicayenzi, Bruce; Crookshank, Meghan C; Bougherara, Habiba; Schemitsch, Emil H; Zdero, Radovan

2014-05-01

The human humerus is the third largest longbone and experiences 2-3% of all fractures. Yet, almost no data exist on its intact biomechanical properties, thus preventing researchers from obtaining a full understanding of humerus behavior during injury and after being repaired with fracture plates and nails. The aim of this experimental study was to compare the biomechanical stiffness and strength of "gold standard" fresh-frozen humeri to a variety of humerus models. A series of five types of intact whole humeri were obtained: human fresh-frozen (n = 19); human embalmed (n = 18); human dried (n = 15); artificial "normal" (n = 12); and artificial "osteoporotic" (n = 12). Humeri were tested under "real world" clinical loading modes for shear stiffness, torsional stiffness, cantilever bending stiffness, and cantilever bending strength. After removing geometric effects, fresh-frozen results were 585.8 ± 181.5 N/mm2 (normalized shear stiffness); 3.1 ± 1.1 N/(mm2 deg) (normalized torsional stiffness); 850.8 ± 347.9 N/mm2 (normalized cantilever stiffness); and 8.3 ± 2.7 N/mm2 (normalized cantilever strength). Compared to fresh-frozen values, statistical equivalence (p ≥ 0.05) was obtained for all four test modes (embalmed humeri), 1 of 4 test modes (dried humeri), 1 of 4 test modes (artificial "normal" humeri), and 1 of 4 test modes (artificial "osteoporotic" humeri). Age and bone mineral density versus experimental results had Pearson linear correlations ranging from R = -0.57 to 0.80. About 77% of human humeri failed via a transverse or oblique distal shaft fracture, whilst 88% of artificial humeri failed with a mixed transverse + oblique fracture. To date, this is the most comprehensive study on the biomechanics of intact human and artificial humeri and can assist researchers to choose an alternate humerus model that can substitute for fresh-frozen humeri.

Calculation of normal modes of the closed waveguides in general vector case

NASA Astrophysics Data System (ADS)

Malykh, M. D.; Sevastianov, L. A.; Tiutiunnik, A. A.

2018-04-01

The article is devoted to the calculation of normal modes of the closed waveguides with an arbitrary filling ɛ, μ in the system of computer algebra Sage. Maxwell equations in the cylinder are reduced to the system of two bounded Helmholtz equations, the notion of weak solution of this system is given and then this system is investigated as a system of ordinary differential equations. The normal modes of this system are an eigenvectors of a matrix pencil. We suggest to calculate the matrix elements approximately and to truncate the matrix by usual way but further to solve the truncated eigenvalue problem exactly in the field of algebraic numbers. This approach allows to keep the symmetry of the initial problem and in particular the multiplicity of the eigenvalues. In the work would be presented some results of calculations.

On the tunability of quality-factor for optical Tamm plasmon modes

NASA Astrophysics Data System (ADS)

Kumar, Samir; Das, Ritwick

2017-09-01

We present a comprehensive investigation to ascertain the impact of gold and silver films on modifying the quality-factor (Q-factor) of optical Tamm-plasmon (OTP) resonance in a metal-distributed Bragg reflector (M-DBR) geometry. Here, OTP mode is excited using direct incidence of white-light-source at normal incidence as well as oblique incidence on M-DBR geometry. The lifetime of OTP in gold and silver deposited films on DBR mirror was determined from OTP resonance linewidth. The lifetime and the Q-factor of OTP modes are found to depend on DBR bilayers, metal film thickness as well as on different plasmon active metals. This finding would facilitate tuning the Q-factor and consequently, the lifetime of OTP modes for various applications in all-optical switches and modulators. In addition, we discuss the spectral characteristics of OTP modes excited using normal and oblique incident of source.

Defect modes in a stacked structure of chiral photonic crystals.

PubMed

Chen, Jiun-Yeu; Chen, Lien-Wen

2005-06-01

An optical propagation simulation is carried out for the study of photonic defect modes in a stacked structure of cholesteric liquid crystal films with spatially varying pitch. The defects are introduced by a pitch jump and a phase jump in the cholesteric helix. The effect of a finite sample thickness on transmission of the defect mode and on the required polarization of incident light to create the defect mode is discussed. For normal and near-normal incidence of circularly polarized light with the same handedness as structure, the defect caused by a pitch jump results in discrete peaks within a forbidden band in the transmission. The particular spectrum is similar to the feature of a Fabry-Pérot interferometer. By introducing an additional phase jump, linear blueshifts of the defect modes in transmission spectra are correlated with an increase in the twist angle.

Vibrational modes of thin oblate clouds of charge

NASA Astrophysics Data System (ADS)

Jenkins, Thomas G.; Spencer, Ross L.

2002-07-01

A numerical method is presented for finding the eigenfunctions (normal modes) and mode frequencies of azimuthally symmetric non-neutral plasmas confined in a Penning trap whose axial thickness is much smaller than their radial size. The plasma may be approximated as a charged disk in this limit; the normal modes and frequencies can be found if the surface charge density profile σ(r) of the disk and the trap bounce frequency profile ωz(r) are known. The dependence of the eigenfunctions and equilibrium plasma shapes on nonideal components of the confining Penning trap fields is discussed. The results of the calculation are compared with the experimental data of Weimer et al. [Phys. Rev. A 49, 3842 (1994)] and it is shown that the plasma in this experiment was probably hollow and had mode displacement functions that were concentrated near the center of the plasma.

Decreased functional connectivity to posterior cingulate cortex in major depressive disorder.

PubMed

Yang, Rui; Gao, Chengge; Wu, Xiaoping; Yang, Junle; Li, Shengbin; Cheng, Hu

2016-09-30

The default mode network (DMN) and its interaction with other key networks such as the salience network and executive network are keys to understand psychiatric and neurological disorders including major depressive disorder (MDD). In this study, we combined independent component analysis and seed based connectivity analysis to study the posterior default mode network between 20 patients with MDD and 25 normal controls, as well as pre-treatment and post-treatment conditions of the patients. Both correlated and anti-correlated networks centered at the posterior cingulate cortex (PCC) were examined (PCC+ and PCC-). Our results showed aberrant functional connectivity of the PCC+ and PCC- networks between patients and normal controls. Specifically, normal controls exhibited significantly higher connectivity between the PCC and frontal/temporal regions for the PCC+ network and stronger connectivity strength between the PCC and the insula/middle frontal cortex for the PCC- network. The overall connectivity strength of the PCC+ and PCC- networks was also significantly lower in MDD. Because the PCC is a hub in the DMN that interacts with other networks, our result suggested a stronger interaction between the DMN and the salience network but a weak interaction between the DMN and the executive network in MDD. The treatment using sertraline did increase the functional connectivity strength, especially in the PCC+ network. Despite a large inter-subject variability in the overall connectivity strengths and change of the PCC network in response to the treatment, a high correlation between change of connectivity strength and the Hamilton depression score was observed for both the PCC+ and PCC- network. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Cooper-pair-condensate fluctuations and plasmons in layered superconductors

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

Cote, R.; Griffin, A.

1993-10-01

Starting from a given attractive potential, we give a systematic analysis of the spin-singlet [ital s]-wave Cooper-pair-condensate fluctuations in a two-dimensional (2D) superconductor. These results are applied to a superlattice of superconducting sheets in which the 2D charge fluctuations are coupled via the Coulomb interaction. Our main interest is how the low-energy Anderson-Bogoliubov (AB) phonon mode in the pair-breaking gap [omega][lt]2[Delta] is modified by the Coulomb interaction. Our formal analysis is valid at arbitrary temperatures. It describes the weakly bound, large-Cooper-pair limit as well as the strongly bound, small-Cooper-pair limit and thus includes both the BCS and Bose-Einstein scenarios (asmore » discussed by Nozieres and Schmitt-Rink as well as Randeira [ital et] [ital al].). A comlete normal-mode analysis is given for a charged BCS superconductor, showing how the repulsive (Coulomb) interaction modifies the collective modes of a neutral superconductor. This complements the recent numerical study carried out by Fertig and Das Sarma. We show that the pair-response function shares the same spectrum as the charge-response function, given by the zero of the longitudinal dielectric function [epsilon]([bold q],[omega]). In 2D and layered superconductors, there is a low-frequency and high-frequency plasmon branch, separated by a relatively narrow particle-hole continuum at around 2[Delta]. The low-frequency ([omega][lt]2[Delta]) plasmon branch is a renormalized version of the AB phonon mode.« less

Dirac perturbations on Schwarzschild-anti-de Sitter spacetimes: Generic boundary conditions and new quasinormal modes

NASA Astrophysics Data System (ADS)

Wang, Mengjie; Herdeiro, Carlos; Jing, Jiliang

2017-11-01

We study Dirac quasinormal modes of Schwarzschild-anti-de Sitter (Schwarzschild-AdS) black holes, following the generic principle for allowed boundary conditions proposed in [M. Wang, C. Herdeiro, and M. O. P. Sampaio, Phys. Rev. D 92, 124006 (2015)., 10.1103/PhysRevD.92.124006]. After deriving the equations of motion for Dirac fields on the aforementioned background, we impose vanishing energy flux boundary conditions to solve these equations. We find a set of two Robin boundary conditions are allowed. These two boundary conditions are used to calculate Dirac normal modes on empty AdS and quasinormal modes on Schwarzschild-AdS black holes. In the former case, we recover the known normal modes of empty AdS; in the latter case, the two sets of Robin boundary conditions lead to two different branches of quasinormal modes. The impact on these modes of the black hole size, the angular momentum quantum number and the overtone number are discussed. Our results show that vanishing energy flux boundary conditions are a robust principle, applicable not only to bosonic fields but also to fermionic fields.

Comments on compressible effects on Alfven normal modes in nonuniform plasmas

NASA Technical Reports Server (NTRS)

Mok, Y.; Einaudi, G.

1990-01-01

The paper discusses the regime of validity of the theory of dissipative Alfven normal modes presented by Mok and Einaudi (1985) and Einaudi and Mok (1985), which was based on the incompressible closure of the system of ideal MHD equations. Some simple extensions of the earlier results to the compressible case are described. In addition, certain misunderstandings of this work, which have appeared in other papers, are clarified.

Spectroscopic (FTIR, FT-Raman), molecular electrostatic potential, NBO and HOMO-LUMO analysis of P-bromobenzene sulfonyl chloride based on DFT calculations

NASA Astrophysics Data System (ADS)

Jeyavijayan, S.

2015-02-01

The FTIR and FT-Raman spectra of P-bromobenzene sulfonyl chloride (P-BBSC) have been recorded in the regions 4000-400 cm-1 and 3500-50 cm-1, respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by density functional theory (DFT/B3LYP) method. A good agreement between experimental and calculated normal modes of vibrations has been observed. A detailed interpretation of the infrared and Raman spectra of P-BBSC is also reported based on total energy distribution (TED). Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The MEP map shows the negative potential sites are on oxygen atoms as well as the positive potential sites are around the hydrogen atoms. The UV-vis spectral analysis of P-BBSC has also been done which confirms the charge transfer of the molecule.

Microphysics of liquid complex plasmas in equilibrium and non-equilibrium systems

NASA Astrophysics Data System (ADS)

Piel, Alexander; Block, Dietmar; Melzer, André; Mulsow, Matthias; Schablinski, Jan; Schella, André; Wieben, Frank; Wilms, Jochen

2018-05-01

The dynamic evolution of the microscopic structure of solid and liquid phases of complex plasmas is studied experimentally and by means of molecular dynamics (MD) simulations. In small finite systems, the cooperative motion can be described in terms of discrete modes. These modes are studied with different experimental approaches. Using diffuse scattered laser light, applying laser tweezer forces to individual particles, and periodic laser pulses, the excitation of modes is investigated. The instantaneous normal mode analysis of experimental data from two-dimensional liquid clusters gives access to the local dynamics of the liquid phase. Our investigations shed light on the role of compressional and shear modes as well as the determination of diffusion constants and melting temperatures in finite systems. Special attention is paid to hydrodynamic situations with a stationary inhomogeneous dust flow. MD simulations allow to study the collective motion in the shell of nearest neighbors, which can be linked to smooth and sudden changes of the macroscopic flow. Finally, the observed micro-motion in all situations above allows to shed light on the preference of shear-like over compressional motion in terms of a minimized potential energy and a dynamic incompressibility.

Dynamic testing and analysis of extension-twist-coupled composite tubular spars

NASA Astrophysics Data System (ADS)

Lake, Renee C.; Izapanah, Amir P.; Baucon, Robert M.

The results from a study aimed at improving the dynamic and aerodynamic characteristics of composite rotor blades through the use of extension-twist elastic coupling are presented. A set of extension-twist-coupled composite tubular spars, representative of the primary load carrying structure within a helicopter rotor blade, was manufactured using four plies of woven graphite/epoxy cloth 'prepreg.' These spars were non-circular in cross section design and were therefore subject to warping deformations. Three cross-sectional geometries were developed: square, D-shape, and flattened ellipse. Results from free-free vibration tests of the spars were compared with results from normal modes and frequency analyses of companion shell-finite-element models developed in MSC/NASTRAN. Five global or 'non-shell' modes were identified within the 0-2000 Hz range for each spar. The frequencies and associated mode shapes for the D-shape spar were correlated with analytical results, showing agreement within 13.8 percent. Frequencies corresponding to the five global mode shapes for the square spar agreed within 9.5 percent of the analytical results. Five global modes were similarly identified for the elliptical spar and agreed within 4.9 percent of the respective analytical results.

Dynamic testing and analysis of extension-twist-coupled composite tubular spars

NASA Technical Reports Server (NTRS)

Lake, Renee C.; Izapanah, Amir P.; Baucon, Robert M.

1992-01-01

The results from a study aimed at improving the dynamic and aerodynamic characteristics of composite rotor blades through the use of extension-twist elastic coupling are presented. A set of extension-twist-coupled composite tubular spars, representative of the primary load carrying structure within a helicopter rotor blade, was manufactured using four plies of woven graphite/epoxy cloth 'prepreg.' These spars were non-circular in cross section design and were therefore subject to warping deformations. Three cross-sectional geometries were developed: square, D-shape, and flattened ellipse. Results from free-free vibration tests of the spars were compared with results from normal modes and frequency analyses of companion shell-finite-element models developed in MSC/NASTRAN. Five global or 'non-shell' modes were identified within the 0-2000 Hz range for each spar. The frequencies and associated mode shapes for the D-shape spar were correlated with analytical results, showing agreement within 13.8 percent. Frequencies corresponding to the five global mode shapes for the square spar agreed within 9.5 percent of the analytical results. Five global modes were similarly identified for the elliptical spar and agreed within 4.9 percent of the respective analytical results.

Impact of gate engineering in enhancement mode n++GaN/InAlN/AlN/GaN HEMTs

NASA Astrophysics Data System (ADS)

Adak, Sarosij; Swain, Sanjit Kumar; Rahaman, Hafizur; Sarkar, Chandan Kumar

2016-12-01

This paper illustrate the effect of gate material engineering on the performance of enhancement mode n++GaN/InAlN/AlN/GaN high electron mobility transistors (HEMTs). A comparative analysis of key device parameters is discussed for the Triple Material Gate (TMG), Dual Material Gate (DMG) and the Single Material Gate (SMG) structure HEMTs by considering the same device dimensions. The simulation results shows that an significant improvement is noticed in the key analysis parameters such as drain current (Id), transconductance (gm), cut off frequency (fT), RF current gain, maximum cut off frequency (fmax) and RF power gain of the gate material engineered devices with respect to SMG normally off n++GaN/InAlN/AlN/GaN HEMTs. This improvement is due to the existence of the perceivable step in the surface potential along the channel which successfully screens the drain potential variation in the source side of the channel for the gate engineering devices. The analysis suggested that the proposed TMG and DMG engineered structure enhancement mode n++GaN/InAlN/AlN/GaN HEMTs can be considered as a potential device for future high speed, microwave and digital application.

Anatomy of the Binary Black Hole Recoil: A Multipolar Analysis

NASA Technical Reports Server (NTRS)

Schnittman, Jeremy; Buonanno, Alessandra; vanMeter, James R.; Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.

2007-01-01

We present a multipolar analysis of the recoil velocity computed in recent numerical simulations of binary black hole coalescence, for both unequal masses and non-zero, non-precessing spins. We show that multipole moments up to and including 1 = 4 are sufficient to accurately reproduce the final recoil velocity (= 98%) and that only a few dominant modes contribute significantly to it (2 95%). We describe how the relative amplitude, and more importantly, the relative phase, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ring-down phases. We also find that the numerical results can be reproduced, to a high level of accuracy, by an effective Newtonian formula for the multipole moments obtained by replacing in the Newtonian formula the radial separation with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasi-normal modes. Analytic formulae, obtained by expressing the multipole moments in terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and amount of '.anti-kick" for each of the simulations. Lastly, we apply this multipolar analysis to understand the remarkable difference between the amplitudes of planar and non-planar kicks for equal-mass spinning black holes.

Comparison of two interpolation methods for empirical mode decomposition based evaluation of radiographic femur bone images.

PubMed

Udhayakumar, Ganesan; Sujatha, Chinnaswamy Manoharan; Ramakrishnan, Swaminathan

2013-01-01

Analysis of bone strength in radiographic images is an important component of estimation of bone quality in diseases such as osteoporosis. Conventional radiographic femur bone images are used to analyze its architecture using bi-dimensional empirical mode decomposition method. Surface interpolation of local maxima and minima points of an image is a crucial part of bi-dimensional empirical mode decomposition method and the choice of appropriate interpolation depends on specific structure of the problem. In this work, two interpolation methods of bi-dimensional empirical mode decomposition are analyzed to characterize the trabecular femur bone architecture of radiographic images. The trabecular bone regions of normal and osteoporotic femur bone images (N = 40) recorded under standard condition are used for this study. The compressive and tensile strength regions of the images are delineated using pre-processing procedures. The delineated images are decomposed into their corresponding intrinsic mode functions using interpolation methods such as Radial basis function multiquadratic and hierarchical b-spline techniques. Results show that bi-dimensional empirical mode decomposition analyses using both interpolations are able to represent architectural variations of femur bone radiographic images. As the strength of the bone depends on architectural variation in addition to bone mass, this study seems to be clinically useful.

The Effect of Background Plasma Temperature on Growth and Damping of Whistler Mode Wave Power in the Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; Malaspina, D.; Jaynes, A. N.

2017-12-01

Whistler mode waves play a dominant role in the energy dynamics of the Earth's magnetosphere. Trajectory of whistler mode waves can be predicted by raytracing. Raytracing is a numerical method which solves the Haselgrove's equations at each time step taking the background plasma parameters in to account. The majority of previous raytracing work was conducted assuming a cold (0 K) background magnetospheric plasma. Here we perform raytracing in a finite temperature plasma with background electron and ion temperatures of a few eV. When encountered with a high energy (>10 keV) electron distribution, whistler mode waves can undergo a power attenuation and/or growth, depending on resonance conditions which are a function of wave frequency, wave normal angle and particle energy. In this work we present the wave power attenuation and growth analysis of whistler mode waves, during the interaction with a high energy electron distribution. We have numerically modelled the high energy electron distribution as an isotropic velocity distribution, as well as an anisotropic bi-Maxwellian distribution. Both cases were analyzed with and without the temperature effects for the background magnetospheric plasma. Finally we compare our results with the whistler mode energy distribution obtained by the EMFISIS instrument hosted at the Van Allen Probe spacecraft.

3-Iodobenzaldehyde: XRD, FT-IR, Raman and DFT studies.

PubMed

Kumar, Chandraju Sadolalu Chidan; Parlak, Cemal; Tursun, Mahir; Fun, Hoong-Kun; Rhyman, Lydia; Ramasami, Ponnadurai; Alswaidan, Ibrahim A; Keşan, Gürkan; Chandraju, Siddegowda; Quah, Ching Kheng

2015-06-15

The structure of 3-iodobenzaldehyde (3IB) was characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The conformational isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 3IB were examined using density functional theory (DFT) method, with the Becke-3-Lee-Yang-Parr (B3LYP) functional and the 6-311+G(3df,p) basis set for all atoms except for iodine. The LANL2DZ effective core basis set was used for iodine. Potential energy distribution (PED) analysis of normal modes was performed to identify characteristic frequencies. 3IB crystallizes in monoclinic space group P21/c with the O-trans form. There is a good agreement between the theoretically predicted structural parameters, and vibrational frequencies and those obtained experimentally. In order to understand halogen effect, 3-halogenobenzaldehyde [XC6H4CHO; X=F, Cl and Br] was also studied theoretically. The free energy difference between the isomers is small but the rotational barrier is about 8kcal/mol. An atypical behavior of fluorine affecting conformational preference is observed. Copyright © 2015 Elsevier B.V. All rights reserved.

Tunable and switchable dual-wavelength dissipative soliton generation in an all-normal-dispersion Yb-doped fiber laser with birefringence fiber filter.

PubMed

Zhang, Z X; Xu, Z W; Zhang, L

2012-11-19

We report the generation of tunable single- and dual-wavelength dissipative solitons in an all-normal-dispersion mode-locked Yb-doped fiber laser, to the best of our knowledge, for the first time. Besides single-wavelength mode-locking, dual-wavelength mode-locking was achieved using an in-line birefringence fiber filter with periodic multiple passbands, which not only allows multiple wavelengths to oscillate simultaneously but also performs spectrum modulation on highly chirped dissipative pulse. Furthermore, taking advantage of the tunability of the birefringence fiber filter, wavelength tuning for both single- and dual-wavelength dissipative soliton mode-locking was realized. The dual-wavelength operation is also switchable. The all-fiber dissipative laser with flexible outputs can meet diverse application needs.

Picosecond ultrasonics study of the vibrational modes of a nanostructure

NASA Astrophysics Data System (ADS)

Antonelli, G. Andrew; Maris, Humphrey J.; Malhotra, Sandra G.; Harper, James M. E.

2002-03-01

We report experiments in which a subpicosecond pump light pulse is used to excite vibrations in a nanostructure consisting of a periodic array of copper wires embedded in a glass matrix on a silicon substrate. The motion of the wires after excitation is detected using a time-delayed probe light pulse. From the measured data, it is possible to determine the frequencies νn and damping rates Γn of a number of the normal modes of the structure. These modes have frequencies lying in the range 1-30 GHz. By comparison of the measured νn and Γn with the frequencies and damping rates calculated from a computer simulation of the vibrations of the nanostructure, we have been able to deduce the vibration patterns of six of the normal modes.

Statistical analysis of m/ n = 2/1 locked and quasi-stationary modes with rotating precursors at DIII-D

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

Sweeney, Ryan Myles; Choi, W.; La Haye, R. J.

A database has been developed to study the evolution, the nonlinear effects on equilibria, and the disruptivity of locked and quasi-stationary modes with poloidal and toroidal mode numbers m = 2 and n = 1 at DIII-D. The analysis of 22500 discharges shows that more than 18% of disruptions are due to locked or quasi-stationary modes with rotating precursors (not including born locked modes). A parameter formulated by the plasma internal inductance l i divided by the safety factor at 95% of the poloidal flux, q 95, is found to exhibit predictive capability over whether a locked mode will cause a disruption or not, and does so up to hundreds of milliseconds before the disruption. Within 20 ms of the disruption, the shortest distance between the island separatrix and the unperturbed last closed flux surface, referred to as d edge, performs comparably tomore » $${{l}_{i}}/{{q}_{95}}$$ in its ability to discriminate disruptive locked modes. Out of all parameters considered, d edge also correlates best with the duration of the locked mode. Disruptivity following a m/n = 2/1 locked mode as a function of the normalized beta, $${{\\beta}_{\\text{N}}}$$ , is observed to peak at an intermediate value, and decrease for high values. The decrease is attributed to the correlation between $${{\\beta}_{\\text{N}}}$$ and q 95 in the DIII-D operational space. Within 50 ms of a locked mode disruption, average behavior includes exponential growth of the n = 1 perturbed field, which might be due to the 2/1 locked mode. Surprisingly, even assuming the aforementioned 2/1 growth, disruptivity following a locked mode shows little dependence on island width up to 20 ms before the disruption. Separately, greater deceleration of the rotating precursor is observed when the wall torque is large. At locking, modes are often observed to align at a particular phase, which is likely related to a residual error field. Timescales associated with the mode evolution are also studied and dictate the response times necessary for disruption avoidance and mitigation. Lastly, observations of the evolution of $${{\\beta}_{\\text{N}}}$$ during a locked mode, the effects of poloidal beta on the saturated width, and the reduction in Shafranov shift during locking are also presented.« less

Statistical analysis of m/ n = 2/1 locked and quasi-stationary modes with rotating precursors at DIII-D

DOE PAGES

Sweeney, Ryan Myles; Choi, W.; La Haye, R. J.; ...

2016-11-01

A database has been developed to study the evolution, the nonlinear effects on equilibria, and the disruptivity of locked and quasi-stationary modes with poloidal and toroidal mode numbers m = 2 and n = 1 at DIII-D. The analysis of 22500 discharges shows that more than 18% of disruptions are due to locked or quasi-stationary modes with rotating precursors (not including born locked modes). A parameter formulated by the plasma internal inductance l i divided by the safety factor at 95% of the poloidal flux, q 95, is found to exhibit predictive capability over whether a locked mode will cause a disruption or not, and does so up to hundreds of milliseconds before the disruption. Within 20 ms of the disruption, the shortest distance between the island separatrix and the unperturbed last closed flux surface, referred to as d edge, performs comparably tomore » $${{l}_{i}}/{{q}_{95}}$$ in its ability to discriminate disruptive locked modes. Out of all parameters considered, d edge also correlates best with the duration of the locked mode. Disruptivity following a m/n = 2/1 locked mode as a function of the normalized beta, $${{\\beta}_{\\text{N}}}$$ , is observed to peak at an intermediate value, and decrease for high values. The decrease is attributed to the correlation between $${{\\beta}_{\\text{N}}}$$ and q 95 in the DIII-D operational space. Within 50 ms of a locked mode disruption, average behavior includes exponential growth of the n = 1 perturbed field, which might be due to the 2/1 locked mode. Surprisingly, even assuming the aforementioned 2/1 growth, disruptivity following a locked mode shows little dependence on island width up to 20 ms before the disruption. Separately, greater deceleration of the rotating precursor is observed when the wall torque is large. At locking, modes are often observed to align at a particular phase, which is likely related to a residual error field. Timescales associated with the mode evolution are also studied and dictate the response times necessary for disruption avoidance and mitigation. Lastly, observations of the evolution of $${{\\beta}_{\\text{N}}}$$ during a locked mode, the effects of poloidal beta on the saturated width, and the reduction in Shafranov shift during locking are also presented.« less

In vivo diagnosis of mammary adenocarcinoma using Raman spectroscopy: an animal model study

NASA Astrophysics Data System (ADS)

Bitar, R. A.; Ribeiro, D. G.; dos Santos, E. A. P.; Ramalho, L. N. Z.; Ramalho, F. S.; Martin, A. A.; Martinho, H. S.

2010-02-01

Breast cancer is the most frequent cancer type in women Worldwide. Sensitivity and specificity of clinical breast examinations have been estimated from clinical trials to be approximately 54 % and 94 %, respectively. Further, approximately 95 % of all positive breast cancer screenings turn out to be false-positive. The optimal method for early detection should be both highly sensitive to ensure that all cancers are detected, and also highly specific to avoid the humanistic and economic costs associated with false-positive results. In vivo optical spectroscopy techniques, Raman in particular, have been pointed out as promising tools to improve the accuracy of screening mammography. The aim of the present study was to apply FT-Raman spectroscopy to discriminate normal and adenocarcinoma breast tissues of Sprague-Dawley female rats. The study was performed on 32 rats divided in the control (N=5) and experimental (N=27) groups. Histological analysis indicated that mammary hyperplasia, cribriform, papillary and solid adenocarcinomas were found in the experimental group subjects. The spectral collection was made using a commercial FT-Raman Spectrometer (Bruker RFS100) equipped with fiber-optic probe (RamProbe) and the spectral region between 900 and 1800 cm-1 was analyzed. Principal Components Analysis, Cluster Analysis, and Linear Discriminant Analysis with cross-validation were applied as spectral classification algorithm. As concluding remarks it is show that normal and adenocarcinoma tissues discriminations was possible (correct proportion for Transcutaneous collection mode was 80.80% and for "Open Sky" mode was 91.70%); however, a conclusive diagnosis among the four lesion subtypes was not possible.

Measurements and Analysis of Reverberation and Clutter Data

DTIC Science & Technology

2007-04-01

triplet arrays and the DRDC ar- ray with combined omnidirectional and dipole sensors. A fast shallow water reverberation model was extended to...Bistatic reverberation models are too slow for inversion, but model-data comparisons will be made using ray -based models, e.g. GSM [11], or normal-mode...July 2000, pp. 1183–1188, European Commission, Luxembourg. Meeting held at Lyon, France. [36] Weinberg, H. and Keenan, R. E. (1996), Gaussian ray

Experimental Design and Analysis of M1A1 Commander/Gunner Performance during CONOPS (Continuous Operations) Using the U-COFT (Unit Conduct of Fire Trainer)

DTIC Science & Technology

1989-09-01

gun b. 7.62-mm coax manchine gun c. Commander’s weapon station caliber .50 machine gun d. M250 grenade launchers 2. Ammunition Simulation a. 105-mm...7.62-mm machine gun f. M250 smoke grenades 3. Normal Mode Simulation a. Stabilized coax machine gun b. Stabilized main gun c. Commander’s weapon d

Mass quantity gauging by RF mode analysis

NASA Technical Reports Server (NTRS)

Collier, R. S.; Ellerbruch, D.; Cruz, J. E.; Stokes, R. W.; Luft, P. E.; Peterson, R. G.; Hiester, A. E.

1973-01-01

Work done to date is reported concerning Radio Frequency Mass Quantity Gauging. Experimental apparatus has been designed and tested which measures the resonant frequencies of a tank in the time domain. These frequencies correspond to the total mass of fluid within the tank. Experimental results are discussed for nitrogen and hydrogen in normal gravity both in the supercritical state and also in the two phase (liquid-gas) region. Theoretical discussions for more general cases are given.

Vibrational Modes of Oblate Clouds of Charge

NASA Astrophysics Data System (ADS)

Jenkins, Thomas; Spencer, Ross L.

2000-10-01

When a nonneutral plasma confined in a Penning trap is allowed time to expand, its shape at global thermal equilibrium is that of a thin oblate spheroid [D. L. Paulson et al., Phys. Plasmas 5, 345 (1998)]. Oscillations similar to those of a drumhead can be externally induced in such a plasma. Although a theory developed by Dubin predicts the frequencies of the various normal modes of oscillation [Phys. Rev. Lett. 66, 2076 (1991)], this theory assumes that the plasma has zero temperature and is confined by an ideal quadrupole electric field. Neither of these conditions is strictly true in experiments [C. S. Weimer et al., Phys. Rev. A 49, 3842 (1994)] where physical properties of the plasma are deduced from measurements of these frequencies, causing the measurements and ideal theory to differ by about 20%. We reformulate the problem of the normal oscillatory modes as a principal-value integral eigenvalue equation, including finite-temperature and non-ideal confinement effects. The equation is solved numerically to obtain the plasma's normal mode frequencies and shapes; reasonable agreement with experiment is obtained.

Capillary jets in normal gravity: Asymptotic stability analysis and excitation using Maxwell and ultrasonic radiation stresses

NASA Astrophysics Data System (ADS)

Lonzaga, Joel Barci

Both modulated ultrasonic radiation pressure and oscillating Maxwell stress from a voltage-modulated ring electrode are employed to excite low-frequency capillary modes of a weakly tapered liquid jet issuing from a nozzle. The capillary modes are waves formed at the surface of the liquid jet. The ultrasound is internally applied to the liquid jet waveguide and is cut off at a location resulting in a significantly enhanced oscillating radiation stress near the cutoff location. Alternatively, the thin electrode can generate a highly localized oscillating Maxwell stress on the jet surface. Experimental evidence shows that a spatially unstable mode with positive group velocity (propagating downstream from the excitation source) and a neutral mode with negative group velocity are both excited. Reflection at the nozzle boundary converts the neutral mode into an unstable one that interferes with the original unstable mode. The interference effect is observed downstream from the source using a laser-based optical extinction technique that detects the surface waves while the modulation frequency is scanned. This technique is very sensitive to small-amplitude disturbances. Existing linear, convective stability analyses on liquid jets accounting for the gravitational effect (i.e. varying radius and velocity) appear to be not applicable to non-slender, slow liquid jets considered here where the gravitational effect is found substantial at low flow rates. The multiple-scales method, asymptotic expansion and WKB approximation are used to derive a dispersion relation for the capillary wave similar to one obtained by Rayleigh but accounting for the gravitational effect. These mathematical tools aided by Langer's transformation are also used to derive a uniformly valid approximation for the acoustic wave propagation in a tapered cylindrical waveguide. The acoustic analytical approximation is validated by finite-element calculations. The jet response is modeled using a hybrid of Fourier analysis and the WKB-type analysis as proposed by Lighthill. The former derives the mode response to a highly localized source while the latter governs the mode propagation in a weakly inhomogeneous jet away from the source.

Structural dynamics and vibrations of damped, aircraft-type structures

NASA Technical Reports Server (NTRS)

Young, Maurice I.

1992-01-01

Engineering preliminary design methods for approximating and predicting the effects of viscous or equivalent viscous-type damping treatments on the free and forced vibration of lightly damped aircraft-type structures are developed. Similar developments are presented for dynamic hysteresis viscoelastic-type damping treatments. It is shown by both engineering analysis and numerical illustrations that the intermodal coupling of the undamped modes arising from the introduction of damping may be neglected in applying these preliminary design methods, except when dissimilar modes of these lightly damped, complex aircraft-type structures have identical or nearly identical natural frequencies. In such cases, it is shown that a relatively simple, additional interaction calculation between pairs of modes exhibiting this 'modal response' phenomenon suffices in the prediction of interacting modal damping fractions. The accuracy of the methods is shown to be very good to excellent, depending on the normal natural frequency separation of the system modes, thereby permitting a relatively simple preliminary design approach. This approach is shown to be a natural precursor to elaborate finite element, digital computer design computations in evaluating the type, quantity, and location of damping treatment.

Atomic torsional modal analysis for high-resolution proteins.

PubMed

Tirion, Monique M; ben-Avraham, Daniel

2015-03-01

We introduce a formulation for normal mode analyses of globular proteins that significantly improves on an earlier one-parameter formulation [M. M. Tirion, Phys. Rev. Lett. 77, 1905 (1996)] that characterized the slow modes associated with protein data bank structures. Here we develop that empirical potential function that is minimized at the outset to include two features essential to reproduce the eigenspectra and associated density of states in the 0 to 300cm-1 frequency range, not merely the slow modes. First, introduction of preferred dihedral-angle configurations via use of torsional stiffness constants eliminates anomalous dispersion characteristics due to insufficiently bound surface side chains and helps fix the spectrum thin tail frequencies (100-300cm-1). Second, we take into account the atomic identities and the distance of separation of all pairwise interactions, improving the spectrum distribution in the 20 to 300cm-1 range. With these modifications, not only does the spectrum reproduce that of full atomic potentials, but we obtain stable reliable eigenmodes for the slow modes and over a wide range of frequencies.

Demixing-stimulated lane formation in binary complex plasma

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

Du, C.-R.; Jiang, K.; Suetterlin, K. R.

2011-11-29

Recently lane formation and phase separation have been reported for experiments with binary complex plasmas in the PK3-Plus laboratory onboard the International Space Station (ISS). Positive non-additivity of particle interactions is known to stimulate phase separation (demixing), but its effect on lane formation is unknown. In this work, we used Langevin dynamics (LD) simulation to probe the role of non-additivity interactions on lane formation. The competition between laning and demixing leads to thicker lanes. Analysis based on anisotropic scaling indices reveals a crossover from normal laning mode to a demixing-stimulated laning mode. Extensive numerical simulations enabled us to identify amore » critical value of the non-additivity parameter {Delta} for the crossover.« less

Invariant characteristics of self-organization modes in Belousov reaction modeling

NASA Astrophysics Data System (ADS)

Glyzin, S. D.; Goryunov, V. E.; Kolesov, A. Yu

2018-01-01

We consider the problem of mathematical modeling of oxidation-reduction oscillatory chemical reactions based on the mechanism of Belousov reaction. The process of the main components interaction in such reaction can be interpreted by a phenomenologically similar to it “predator-prey” model. Thereby, we consider a parabolic boundary value problem consisting of three Volterra-type equations, which is a mathematical model of this reaction. We carry out a local study of the neighborhood of the system’s non-trivial equilibrium state and construct the normal form of the considering system. Finally, we do a numerical analysis of the coexisting chaotic oscillatory modes of the boundary value problem in a flat area, which have different nature and occur as the diffusion coefficient decreases.

On the dynamical basis of the classification of normal galaxies

PubMed Central

Haass, J.; Bertin, G.; Lin, C. C.

1982-01-01

Some realistic galaxy models have been found to support discrete unstable spiral modes. Here, through the study of the relevant physical mechanisms and an extensive numerical investigation of the properties of the dominant modes in a wide class of galactic equilibria, we show how spiral structures are excited with different morphological features, depending on the properties of the equilibrium model. We identify the basic dynamical parameters and mechanisms and compare the resulting morphology of spiral modes with the actual classification of galaxies. The present study suggests a dynamical basis for the transition among various types and subclasses of normal and barred spiral galaxies. Images PMID:16593200

A Guided Tour of Mathematical Methods for the Physical Sciences

NASA Astrophysics Data System (ADS)

Snieder, Roel; van Wijk, Kasper

2015-05-01

1. Introduction; 2. Dimensional analysis; 3. Power series; 4. Spherical and cylindrical coordinates; 5. Gradient; 6. Divergence of a vector field; 7. Curl of a vector field; 8. Theorem of Gauss; 9. Theorem of Stokes; 10. The Laplacian; 11. Scale analysis; 12. Linear algebra; 13. Dirac delta function; 14. Fourier analysis; 15. Analytic functions; 16. Complex integration; 17. Green's functions: principles; 18. Green's functions: examples; 19. Normal modes; 20. Potential-field theory; 21. Probability and statistics; 22. Inverse problems; 23. Perturbation theory; 24. Asymptotic evaluation of integrals; 25. Conservation laws; 26. Cartesian tensors; 27. Variational calculus; 28. Epilogue on power and knowledge.

Amide I vibrational circular dichroism of dipeptide: Conformation dependence and fragment analysis

NASA Astrophysics Data System (ADS)

Choi, Jun-Ho; Cho, Minhaeng

2004-03-01

The amide I vibrational circular dichroic response of alanine dipeptide analog (ADA) was theoretically investigated and the density functional theory calculation and fragment analysis results are presented. A variety of vibrational spectroscopic properties, local and normal mode frequencies, coupling constant, dipole, and rotational strengths, are calculated by varying two dihedral angles determining the three-dimensional ADA conformation. Considering two monopeptide fragments separately, we show that the amide I vibrational circular dichroism of the ADA can be quantitatively predicted. For several representative conformations of the model ADA, vibrational circular dichroism spectra are calculated by using both the density functional theory calculation and fragment analysis methods.

Bernstein modes in a non-neutral plasma column

NASA Astrophysics Data System (ADS)

Walsh, Daniel; Dubin, Daniel H. E.

2018-05-01

This paper presents theory and numerical calculations of electrostatic Bernstein modes in an inhomogeneous cylindrical plasma column. These modes rely on finite Larmor radius effects to propagate radially across the column until they are reflected when their frequency matches the upper hybrid frequency. This reflection sets up an internal normal mode on the column and also mode-couples to the electrostatic surface cyclotron wave (which allows the normal mode to be excited and observed using external electrodes). Numerical results predicting the mode spectra, using a novel linear Vlasov code on a cylindrical grid, are presented and compared to an analytical Wentzel Kramers Brillouin (WKB) theory. A previous version of the theory [D. H. E. Dubin, Phys. Plasmas 20(4), 042120 (2013)] expanded the plasma response in powers of 1/B, approximating the local upper hybrid frequency, and consequently, its frequency predictions are spuriously shifted with respect to the numerical results presented here. A new version of the WKB theory avoids this approximation using the exact cold fluid plasma response and does a better job of reproducing the numerical frequency spectrum. The effect of multiple ion species on the mode spectrum is also considered, to make contact with experiments that observe cyclotron modes in a multi-species pure ion plasma [M. Affolter et al., Phys. Plasmas 22(5), 055701 (2015)].

Mode-specific tunneling using the Qim path: theory and an application to full-dimensional malonaldehyde.

PubMed

Wang, Yimin; Bowman, Joel M

2013-10-21

We present a theory of mode-specific tunneling that makes use of the general tunneling path along the imaginary-frequency normal mode of the saddle point, Qim, and the associated relaxed potential, V(Qim) [Y. Wang and J. M. Bowman, J. Chem. Phys. 129, 121103 (2008)]. The novel aspect of the theory is the projection of the normal modes of a minimum onto the Qim path and the determination of turning points on V(Qim). From that projection, the change in tunneling upon mode excitation can be calculated. If the projection is zero, no enhancement of tunneling is predicted. In that case vibrationally adiabatic (VA) theory could apply. However, if the projection is large then VA theory is not applicable. The approach is applied to mode-specific tunneling in full-dimensional malonaldehyde, using an accurate full-dimensional potential energy surface. Results are in semi-quantitative agreement with experiment for modes that show large enhancement of the tunneling, relative to the ground state tunneling splitting. For the six out-of-plane modes, which have zero projection on the planar Qim path, VA theory does apply, and results from that theory agree qualitatively and even semi-quantitatively with experiment. We also verify the failure of simple VA theory for modes that show large enhancement of tunneling.

Use of Simpson's method of disc to detect early echocardiographic changes in Doberman Pinschers with dilated cardiomyopathy.

PubMed

Wess, G; Mäurer, J; Simak, J; Hartmann, K

2010-01-01

M-mode is the echocardiographic gold standard to diagnose dilated cardiomyopathy (DCM) in dogs, whereas Simpson's method of discs (SMOD) is the preferred method to detect echocardiographic evidence of disease in humans. To establish reference values for SMOD and to compare those with M-mode measurements. Nine hundred and sixty-nine examinations of 471 Doberman Pinschers. Using a prospective longitudinal study design. Reference values for SMOD were established using 75 healthy Doberman Pinschers >8 years old with <50 ventricular premature contractions (VPCs) in 24 hours. The ability of the new SMOD cut-off values, normalized to body surface area (BSA), for left ventricular end-diastolic volume (LVEDV/BSA >95mL/m(2) ) and end-systolic volume (LVESV/BSA > 55mL/m(2) ) to detect echocardiographic changes in Doberman Pinschers with DCM was compared with currently recommended M-mode values. Dogs with elevated SMOD values but normal M-mode measurements were followed-up using a prospective longitudinal study design. At the final examination 175 dogs were diagnosed with DCM according to both methods (M-mode and SMOD). At previous examinations, M-mode values were abnormal in 142 examinations only, whereas all 175 SMOD already had detected changes. Additionally, 19 of 154 dogs with >100 VPCs/24 hours and normal M-mode values had abnormal SMOD measurement. Six dogs with increased SMOD measurements remained healthy at several follow-up examinations (classified as false positive); in 24 dogs with increased SMOD measurements, no follow-up examinations were available (classified as unclear). SMOD measurements are superior to M-mode to detect early echocardiographic changes in Dobermans with occult DCM. Copyright © 2010 by the American College of Veterinary Internal Medicine.

Mechanical Fault Diagnosis of High Voltage Circuit Breakers Based on Variational Mode Decomposition and Multi-Layer Classifier.

PubMed

Huang, Nantian; Chen, Huaijin; Cai, Guowei; Fang, Lihua; Wang, Yuqiang

2016-11-10

Mechanical fault diagnosis of high-voltage circuit breakers (HVCBs) based on vibration signal analysis is one of the most significant issues in improving the reliability and reducing the outage cost for power systems. The limitation of training samples and types of machine faults in HVCBs causes the existing mechanical fault diagnostic methods to recognize new types of machine faults easily without training samples as either a normal condition or a wrong fault type. A new mechanical fault diagnosis method for HVCBs based on variational mode decomposition (VMD) and multi-layer classifier (MLC) is proposed to improve the accuracy of fault diagnosis. First, HVCB vibration signals during operation are measured using an acceleration sensor. Second, a VMD algorithm is used to decompose the vibration signals into several intrinsic mode functions (IMFs). The IMF matrix is divided into submatrices to compute the local singular values (LSV). The maximum singular values of each submatrix are selected as the feature vectors for fault diagnosis. Finally, a MLC composed of two one-class support vector machines (OCSVMs) and a support vector machine (SVM) is constructed to identify the fault type. Two layers of independent OCSVM are adopted to distinguish normal or fault conditions with known or unknown fault types, respectively. On this basis, SVM recognizes the specific fault type. Real diagnostic experiments are conducted with a real SF₆ HVCB with normal and fault states. Three different faults (i.e., jam fault of the iron core, looseness of the base screw, and poor lubrication of the connecting lever) are simulated in a field experiment on a real HVCB to test the feasibility of the proposed method. Results show that the classification accuracy of the new method is superior to other traditional methods.

Mechanical Fault Diagnosis of High Voltage Circuit Breakers Based on Variational Mode Decomposition and Multi-Layer Classifier

PubMed Central

Huang, Nantian; Chen, Huaijin; Cai, Guowei; Fang, Lihua; Wang, Yuqiang

2016-01-01

Mechanical fault diagnosis of high-voltage circuit breakers (HVCBs) based on vibration signal analysis is one of the most significant issues in improving the reliability and reducing the outage cost for power systems. The limitation of training samples and types of machine faults in HVCBs causes the existing mechanical fault diagnostic methods to recognize new types of machine faults easily without training samples as either a normal condition or a wrong fault type. A new mechanical fault diagnosis method for HVCBs based on variational mode decomposition (VMD) and multi-layer classifier (MLC) is proposed to improve the accuracy of fault diagnosis. First, HVCB vibration signals during operation are measured using an acceleration sensor. Second, a VMD algorithm is used to decompose the vibration signals into several intrinsic mode functions (IMFs). The IMF matrix is divided into submatrices to compute the local singular values (LSV). The maximum singular values of each submatrix are selected as the feature vectors for fault diagnosis. Finally, a MLC composed of two one-class support vector machines (OCSVMs) and a support vector machine (SVM) is constructed to identify the fault type. Two layers of independent OCSVM are adopted to distinguish normal or fault conditions with known or unknown fault types, respectively. On this basis, SVM recognizes the specific fault type. Real diagnostic experiments are conducted with a real SF6 HVCB with normal and fault states. Three different faults (i.e., jam fault of the iron core, looseness of the base screw, and poor lubrication of the connecting lever) are simulated in a field experiment on a real HVCB to test the feasibility of the proposed method. Results show that the classification accuracy of the new method is superior to other traditional methods. PMID:27834902

Investigation of Antihyperglycaemic Activity of Banana (Musa sp. Var. Nanjangud rasa bale) Flower in Normal and Diabetic Rats.

PubMed

Ramu, Ramith; Shirahatti, Prithvi S; Dhanabal, S P; Zameer, Farhan; Dhananjaya, B L; Nagendra Prasad, M N

2017-10-01

The vital enzymes of starch digestion and absorption are intestinal α-glucosidases and their inhibition improves postprandial hyperglycaemia, constituting an effective mode of therapy in diabetes. The present study was designed to assess the inhibitory potential of ethanol extract of banana flower (EF) on mammalian α-glucosidases and its pharmacological effects on postprandial hyperglycaemia in normal and alloxan-induced diabetic rats. EF was evaluated for its inhibitory potential and mode of inhibition on mammalian α-glucosidases. Further, the role of EF and its constituents Umbelliferone (C1) and Lupeol (C2) on glucose uptake using isolated rat hemi-diaphragm and insulinotropic activity using RINm5F (rat insulinoma) cell lines were determined. The phytocomponents in EF were also evaluated using GC-MS. EF illustrated a dose-dependent inhibition for rat intestinal sucrase, maltase and p -nitrophenyl-α-D-glucopyranoside (pNPG) hydrolysis (IC 50 values: 18.76±0.22, 25.54±0.10 and 76.42±1.12 µg/ml, respectively) and the mode of inhibition was non-competitive with low Ki values. Oral administration (100-200 mg/kg b.wt.) of EF significantly improved the maltose/glucose-induced postprandial hyperglycaemia in normal and alloxan-induced diabetic rats. EF, C1 and C2 exhibited stimulation of glucose uptake and a dose-dependent glucose-induced insulin secretion at both 4.5 and 16.7 mM glucose concentrations. Further, GC-MS analysis revealed significant levels of steroids (25.61%), diazoprogesterone (21.31%), sesquiterpene (11.78%) and other phytocomponents. EF inhibited α-glucosidases besides promoting glucose uptake and insulin secretion, resulting in antihyperglycaemic effect determining EF as a potent anti-diabetic agent. Abbreviations used: mg/dl: milligramsper deciliter, mM: millimolar, b.wt.: body weight.

The influence of anharmonic and solvent effects on the theoretical vibrational spectra of the guanine-cytosine base pairs in Watson-Crick and Hoogsteen configurations.

PubMed

Bende, Attila; Muntean, Cristina M

2014-03-01

The theoretical IR and Raman spectra of the guanine-cytosine DNA base pairs in Watson-Crick and Hoogsteen configurations were computed using DFT method with M06-2X meta-hybrid GGA exchange-correlation functional, including the anharmonic corrections and solvent effects. The results for harmonic frequencies and their anharmonic corrections were compared with our previously calculated values obtained with the B3PW91 hybrid GGA functional. Significant differences were obtained for the anharmonic corrections calculated with the two different DFT functionals, especially for the stretching modes, while the corresponding harmonic frequencies did not differ considerable. For the Hoogtseen case the H⁺ vibration between the G-C base pair can be characterized as an asymmetric Duffing oscillator and therefore unrealistic anharmonic corrections for normal modes where this proton vibration is involved have been obtained. The spectral modification due to the anharmonic corrections, solvent effects and the influence of sugar-phosphate group for the Watson-Crick and Hoogsteen base pair configurations, respectively, were also discussed. For the Watson-Crick case also the influence of the stacking interaction on the theoretical IR and Raman spectra was analyzed. Including the anharmonic correction in our normal mode analysis is essential if one wants to obtain correct assignments of the theoretical frequency values as compared with the experimental spectra.

Nature of the wiggle instability of galactic spiral shocks

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

Kim, Woong-Tae; Kim, Yonghwi; Kim, Jeong-Gyu, E-mail: wkim@astro.snu.ac.kr, E-mail: kimyh@astro.snu.ac.kr, E-mail: jgkim@astro.snu.ac.kr

Gas in disk galaxies interacts nonlinearly with an underlying stellar spiral potential to form galactic spiral shocks. While numerical simulations typically show that spiral shocks are unstable to wiggle instability (WI) even in the absence of magnetic fields and self-gravity, its physical nature has remained uncertain. To clarify the mechanism behind the WI, we conduct a normal-mode linear stability analysis and nonlinear simulations assuming that the disk is isothermal and infinitesimally thin. We find that the WI is physical, originating from the generation of potential vorticity at a deformed shock front, rather than Kelvin-Helmholtz instabilities as previously thought. Since gasmore » in galaxy rotation periodically passes through the shocks multiple times, the potential vorticity can accumulate successively, setting up a normal mode that grows exponentially with time. Eigenfunctions of the WI decay exponentially downstream from the shock front. Both shock compression of acoustic waves and a discontinuity of shear across the shock stabilize the WI. The wavelength and growth time of the WI depend on the arm strength quite sensitively. When the stellar-arm forcing is moderate at 5%, the wavelength of the most unstable mode is about 0.07 times the arm-to-arm spacing, with the growth rate comparable to the orbital angular frequency, which is found to be in good agreement with the results of numerical simulations.« less

Probable autosomal recessive Marfan syndrome.

PubMed Central

Fried, K; Krakowsky, D

1977-01-01

A probable autosomal recessive mode of inheritance is described in a family with two affected sisters. The sisters showed the typical picture of Marfan syndrome and were of normal intelligence. Both parents and all four grandparents were personally examined and found to be normal. Homocystinuria was ruled out on repeated examinations. This family suggests genetic heterogeneity in Marfan syndrome and that in some rare families the mode of inheritance may be autosomal recessive. Images PMID:592353

Analytical and Experimental Random Vibration of Nonlinear Aeroelastic Structures.

DTIC Science & Technology

1987-01-28

firstorder differential equations. In view of the system complexi- ty an attempt s made to close the infinite hierarchy by using a Gaussian scheme. This sc...year of this project-. When the first normal mode is externally excited by a band-limited random excitation, the system mean square response is found...governed mainly by the internal detuning parameter and the system damping ratios. The results are completely different when the second normal mode is

Fault detection and diagnosis using neural network approaches

NASA Technical Reports Server (NTRS)

Kramer, Mark A.

1992-01-01

Neural networks can be used to detect and identify abnormalities in real-time process data. Two basic approaches can be used, the first based on training networks using data representing both normal and abnormal modes of process behavior, and the second based on statistical characterization of the normal mode only. Given data representative of process faults, radial basis function networks can effectively identify failures. This approach is often limited by the lack of fault data, but can be facilitated by process simulation. The second approach employs elliptical and radial basis function neural networks and other models to learn the statistical distributions of process observables under normal conditions. Analytical models of failure modes can then be applied in combination with the neural network models to identify faults. Special methods can be applied to compensate for sensor failures, to produce real-time estimation of missing or failed sensors based on the correlations codified in the neural network.

Normal Modes Expose Active Sites in Enzymes.

PubMed

Glantz-Gashai, Yitav; Meirson, Tomer; Samson, Abraham O

2016-12-01

Accurate prediction of active sites is an important tool in bioinformatics. Here we present an improved structure based technique to expose active sites that is based on large changes of solvent accessibility accompanying normal mode dynamics. The technique which detects EXPOsure of active SITes through normal modEs is named EXPOSITE. The technique is trained using a small 133 enzyme dataset and tested using a large 845 enzyme dataset, both with known active site residues. EXPOSITE is also tested in a benchmark protein ligand dataset (PLD) comprising 48 proteins with and without bound ligands. EXPOSITE is shown to successfully locate the active site in most instances, and is found to be more accurate than other structure-based techniques. Interestingly, in several instances, the active site does not correspond to the largest pocket. EXPOSITE is advantageous due to its high precision and paves the way for structure based prediction of active site in enzymes.

Normal Modes Expose Active Sites in Enzymes

PubMed Central

Glantz-Gashai, Yitav; Samson, Abraham O.

2016-01-01

Accurate prediction of active sites is an important tool in bioinformatics. Here we present an improved structure based technique to expose active sites that is based on large changes of solvent accessibility accompanying normal mode dynamics. The technique which detects EXPOsure of active SITes through normal modEs is named EXPOSITE. The technique is trained using a small 133 enzyme dataset and tested using a large 845 enzyme dataset, both with known active site residues. EXPOSITE is also tested in a benchmark protein ligand dataset (PLD) comprising 48 proteins with and without bound ligands. EXPOSITE is shown to successfully locate the active site in most instances, and is found to be more accurate than other structure-based techniques. Interestingly, in several instances, the active site does not correspond to the largest pocket. EXPOSITE is advantageous due to its high precision and paves the way for structure based prediction of active site in enzymes. PMID:28002427

Density and spin modes in imbalanced normal Fermi gases from collisionless to hydrodynamic regime

NASA Astrophysics Data System (ADS)

Narushima, Masato; Watabe, Shohei; Nikuni, Tetsuro

2018-03-01

We study the mass- and population-imbalance effect on density (in-phase) and spin (out-of-phase) collective modes in a two-component normal Fermi gas. By calculating the eigenmodes of the linearized Boltzmann equation as well as the density/spin dynamic structure factor, we show that mass- and population-imbalance effects offer a variety of collective mode crossover behaviors from collisionless to hydrodynamic regimes. The mass-imbalance effect shifts the crossover regime to the higher-temperature, and a significant peak of the spin dynamic structure factor emerges only in the collisionless regime. This is in contrast to the case of mass- and population-balanced normal Fermi gases, where the spin dynamic response is always absent. Although the population-imbalance effect does not shift the crossover regime, the spin dynamic structure factor survives both in the collisionless and hydrodynamic regimes.

Experimental observation of different soliton types in a net-normal group-dispersion fiber laser.

PubMed

Feng, Zhongyao; Rong, Qiangzhou; Qiao, Xueguang; Shao, Zhihua; Su, Dan

2014-09-20

Different soliton types are observed in a net-normal group-dispersion fiber laser based on nonlinear polarization rotation for passive mode locking. The proposed laser can deliver a dispersion-managed soliton, typical dissipation solitons, and a quasi-harmonic mode-locked pulse, a soliton bundle, and especially a dark pulse by only appropriately adjusting the linear cavity phase delay bias using one polarization controller at the fixed pump power. These nonlinear waves show different features, including the spectral shapes and time traces. The experimental observations show that the five soliton types could exist in the same laser cavity, which implies that integrable systems, dissipative systems, and dark pulse regimes can transfer and be switched in a passively mode-locked laser. Our studies not only verify the numeral simulation of the different soliton-types formation in a net-normal group-dispersion operation but also provide insight into Ginzburg-Landau equation systems.

High-frequency Born synthetic seismograms based on coupled normal modes

USGS Publications Warehouse

Pollitz, Fred F.

2011-01-01

High-frequency and full waveform synthetic seismograms on a 3-D laterally heterogeneous earth model are simulated using the theory of coupled normal modes. The set of coupled integral equations that describe the 3-D response are simplified into a set of uncoupled integral equations by using the Born approximation to calculate scattered wavefields and the pure-path approximation to modulate the phase of incident and scattered wavefields. This depends upon a decomposition of the aspherical structure into smooth and rough components. The uncoupled integral equations are discretized and solved in the frequency domain, and time domain results are obtained by inverse Fourier transform. Examples show the utility of the normal mode approach to synthesize the seismic wavefields resulting from interaction with a combination of rough and smooth structural heterogeneities. This approach is applied to an ∼4 Hz shallow crustal wave propagation around the site of the San Andreas Fault Observatory at Depth (SAFOD).

S-Wave Normal Mode Propagation in Aluminum Cylinders

USGS Publications Warehouse

Lee, Myung W.; Waite, William F.

2010-01-01

Large amplitude waveform features have been identified in pulse-transmission shear-wave measurements through cylinders that are long relative to the acoustic wavelength. The arrival times and amplitudes of these features do not follow the predicted behavior of well-known bar waves, but instead they appear to propagate with group velocities that increase as the waveform feature's dominant frequency increases. To identify these anomalous features, the wave equation is solved in a cylindrical coordinate system using an infinitely long cylinder with a free surface boundary condition. The solution indicates that large amplitude normal-mode propagations exist. Using the high-frequency approximation of the Bessel function, an approximate dispersion relation is derived. The predicted amplitude and group velocities using the approximate dispersion relation qualitatively agree with measured values at high frequencies, but the exact dispersion relation should be used to analyze normal modes for full ranges of frequency of interest, particularly at lower frequencies.

Telephone-quality pathological speech classification using empirical mode decomposition.

PubMed

Kaleem, M F; Ghoraani, B; Guergachi, A; Krishnan, S

2011-01-01

This paper presents a computationally simple and effective methodology based on empirical mode decomposition (EMD) for classification of telephone quality normal and pathological speech signals. EMD is used to decompose continuous normal and pathological speech signals into intrinsic mode functions, which are analyzed to extract physically meaningful and unique temporal and spectral features. Using continuous speech samples from a database of 51 normal and 161 pathological speakers, which has been modified to simulate telephone quality speech under different levels of noise, a linear classifier is used with the feature vector thus obtained to obtain a high classification accuracy, thereby demonstrating the effectiveness of the methodology. The classification accuracy reported in this paper (89.7% for signal-to-noise ratio 30 dB) is a significant improvement over previously reported results for the same task, and demonstrates the utility of our methodology for cost-effective remote voice pathology assessment over telephone channels.

Comparison of diagnostic capability of macular ganglion cell complex and retinal nerve fiber layer among primary open angle glaucoma, ocular hypertension, and normal population using Fourier-domain optical coherence tomography and determining their functional correlation in Indian population

PubMed Central

Barua, Nabanita; Sitaraman, Chitra; Goel, Sonu; Chakraborti, Chandana; Mukherjee, Sonai; Parashar, Hemandra

2016-01-01

Context: Analysis of diagnostic ability of macular ganglionic cell complex and retinal nerve fiber layer (RNFL) in glaucoma. Aim: To correlate functional and structural parameters and comparing predictive value of each of the structural parameters using Fourier-domain (FD) optical coherence tomography (OCT) among primary open angle glaucoma (POAG) and ocular hypertension (OHT) versus normal population. Setting and Design: Single centric, cross-sectional study done in 234 eyes. Materials and Methods: Patients were enrolled in three groups: POAG, ocular hypertensive and normal (40 patients in each group). After comprehensive ophthalmological examination, patients underwent standard automated perimetry and FD-OCT scan in optic nerve head and ganglion cell mode. The relationship was assessed by correlating ganglion cell complex (GCC) parameters with mean deviation. Results were compared with RNFL parameters. Statistical Analysis: Data were analyzed with SPSS, analysis of variance, t-test, Pearson's coefficient, and receiver operating curve. Results: All parameters showed strong correlation with visual field (P < 0.001). Inferior GCC had highest area under curve (AUC) for detecting glaucoma (0.827) in POAG from normal population. However, the difference was not statistically significant (P > 0.5) when compared with other parameters. None of the parameters showed significant diagnostic capability to detect OHT from normal population. In diagnosing early glaucoma from OHT and normal population, only inferior GCC had statistically significant AUC value (0.715). Conclusion: In this study, GCC and RNFL parameters showed equal predictive capability in perimetric versus normal group. In early stage, inferior GCC was the best parameter. In OHT population, single day cross-sectional imaging was not valuable. PMID:27221682

Breaking Through the Multi-Mesa-Channel Width Limited of Normally Off GaN HEMTs Through Modulation of the Via-Hole-Length.

PubMed

Chien, Cheng-Yen; Wu, Wen-Hsin; You, Yao-Hong; Lin, Jun-Huei; Lee, Chia-Yu; Hsu, Wen-Ching; Kuan, Chieh-Hsiung; Lin, Ray-Ming

2017-12-01

We present new normally off GaN high-electron-mobility transistors (HEMTs) that overcome the typical limitations in multi-mesa-channel (MMC) width through modulation of the via-hole-length to regulate the charge neutrality screen effect. We have prepared enhancement-mode (E-mode) GaN HEMTs having widths of up to 300 nm, based on an enhanced surface pinning effect. E-mode GaN HEMTs having MMC structures and widths as well as via-hole-lengths of 100 nm/2 μm and 300 nm/6 μm, respectively, exhibited positive threshold voltages (V th ) of 0.79 and 0.46 V, respectively. The on-resistances of the MMC and via-hole-length structures were lower than those of typical tri-gate nanoribbon GaN HEMTs. In addition, the devices not only achieved the E-mode but also improved the power performance of the GaN HEMTs and effectively mitigated the device thermal effect. We controlled the via-hole-length sidewall surface pinning effect to obtain the E-mode GaN HEMTs. Our findings suggest that via-hole-length normally off GaN HEMTs have great potential for use in next-generation power electronics.

Ambulatory heart rate range predicts mode-specific mortality and hospitalisation in chronic heart failure

PubMed Central

Cubbon, Richard M; Ruff, Naomi; Groves, David; Eleuteri, Antonio; Denby, Christine; Kearney, Lorraine; Ali, Noman; Walker, Andrew M N; Jamil, Haqeel; Gierula, John; Gale, Chris P; Batin, Phillip D; Nolan, James; Shah, Ajay M; Fox, Keith A A; Sapsford, Robert J; Witte, Klaus K; Kearney, Mark T

2016-01-01

Objective We aimed to define the prognostic value of the heart rate range during a 24 h period in patients with chronic heart failure (CHF). Methods Prospective observational cohort study of 791 patients with CHF associated with left ventricular systolic dysfunction. Mode-specific mortality and hospitalisation were linked with ambulatory heart rate range (AHRR; calculated as maximum minus minimum heart rate using 24 h Holter monitor data, including paced and non-sinus complexes) in univariate and multivariate analyses. Findings were then corroborated in a validation cohort of 408 patients with CHF with preserved or reduced left ventricular ejection fraction. Results After a mean 4.1 years of follow-up, increasing AHRR was associated with reduced risk of all-cause, sudden, non-cardiovascular and progressive heart failure death in univariate analyses. After accounting for characteristics that differed between groups above and below median AHRR using multivariate analysis, AHRR remained strongly associated with all-cause mortality (HR 0.991/bpm increase in AHRR (95% CI 0.999 to 0.982); p=0.046). AHRR was not associated with the risk of any non-elective hospitalisation, but was associated with heart-failure-related hospitalisation. AHRR was modestly associated with the SD of normal-to-normal beats (R2=0.2; p<0.001) and with peak exercise-test heart rate (R2=0.33; p<0.001). Analysis of the validation cohort revealed AHRR to be associated with all-cause and mode-specific death as described in the derivation cohort. Conclusions AHRR is a novel and readily available prognosticator in patients with CHF, which may reflect autonomic tone and exercise capacity. PMID:26674986