Density Analysis Method Research Articles

Numerical Analysis for the Prediction of Microstructure after Hot Forming of Structural Metals

The importance of structural metals for industrial applications is based on their superior combination of mechanical properties—strength, elongation, toughness and corrosion resistance—achieved at the end of forming processes. A numerical analysis for the prediction of microstructure is strongly required for the optimization of hot forming process parameters, because the microstructure of structural metals, which has the significant effects on mechanical properties, is strongly dependent to forming process conditions as well as the chemical composition. The incremental dislocation density and microstructural evolution analysis method enables the prediction of the change in microstructure after forming. The outline of the analytical scheme is explained briefly, and the results of its application to strip rolling, bar rolling and shape rolling are presented. Finally, the remaining research topics in this field are discussed. [doi:10.2320/matertrans.MF200906]

Gender differences in the relationship between heart rate control and adiposity in young children: a cross-sectional study (EarlyBird 33)

The role of the autonomic nervous system in the complex link between insulin resistance and cardiovascular risk remains unclear. Increased sympathetic nervous system activity has been implicated in the pathophysiology of insulin resistance but is confounded by a number of factors. We have therefore examined the relationship among cardiac autonomic control, insulin resistance, habitual physical activity, resting energy expenditure (REE), and anthropometric variables in a subset (107 boys, 101 girls, age 9 +/- 0.25 yr) of the EarlyBird cohort. Cardiac autonomic activity was assessed using time domain and power spectral density analysis methods of heart rate variability. Insulin resistance was measured using homeostasis model assessment of insulin resistance (HOMA2-IR). Girls, in comparison to boys, showed significantly higher resting heart rate and lower systolic blood pressure (BP); were more insulin resistant; undertook less physical activity, and had lower fat-free mass and REE. Increasing fasting insulin and increasing insulin resistance were associated with increasing BP. The data suggest early gender differences in predictors of cardiac autonomic control. Pubertal staging was not undertaken in this study, and we plan to evaluate this in future studies to further clarify these associations.

Vibronic Coupling in Naphthalene Anion: Vibronic Coupling Density Analysis for Totally Symmetric Vibrational Modes

Vibronic coupling, or electron-phonon coupling, of naphthalene is calculated. A method of vibronic coupling density analysis, which has been proposed for the vibronic coupling of the Jahn-Teller active modes in a Jahn-Teller molecule, is extended for totally symmetric vibrational modes of a molecule including a non-Jahn-Teller molecule. Contrary to non-totally-symmetric modes, orbital relaxation upon a charge transfer plays a crucial role in the vibronic coupling calculation for the totally symmetric modes. The method is applied for the ground state of the naphthalene anion to compare with that of the benzene anion. The relationship between the vibronic coupling density and a nuclear Fukui function is also discussed.

Intracortical Circuits in Rat Anterior Cingulate Cortex Are Activated by Nociceptive Inputs Mediated by Medial Thalamus

We investigated the afferents and intracortical synaptic organization of the anterior cingulate cortex (ACC) during noxious electrical stimulation. Extracellular field potentials were recorded simultaneously from 16 electrodes spanning all layers of the ACC in male Sprague-Dawley rats anesthetized by halothane inhalation. Laminar-specific transmembrane currents were calculated with the current source density analysis method. Two major groups of evoked sink currents were identified: an early group (latency = 54.04 +/- 2.12 ms; 0.63 +/- 0.07 mV/mm(2)) in layers V-VI and a more intense late group (latency = 80.07 +/- 4.85 ms; 2.16 +/- 0.22 mV/mm(2)) in layer II/III and layer V. Multiunit activities were evoked mainly in layer V and deep layer II/III with latencies similar to that of the early and late sink groups. The evoked EPSP latencies of pyramidal neurons in layers II/III and V related closely with the sink currents. The sink currents were inhibited by intracortical injection of CNQX (1 mM, 1 microl), a glutaminergic receptor antagonist, and enhanced by intraperitoneal (5 mg/kg) and intracortical (10 microg/microl, 1 microl) injection of morphine, a mu-opioid receptor agonist. Paired-pulse depression was observed with interpulse intervals of 50 to 1,000 ms. High-frequency stimulation (100 Hz, 11 pulses) enhanced evoked responses in the ACC and evoked medial thalamic (MT) unit activities. MT lesions blocked evoked responses in the ACC. Our results demonstrated that two distinct synaptic circuits in the ACC were activated by noxious stimuli and that the MT is the major thalamic relay that transmits nociceptive information to the ACC.

Density Determination by Water Displacement and Flotation: An Introductory Experiment in Forensic Chemistry

An introductory lab experiment has been developed for a nonscience major course in forensic chemistry, designed to introduce students to basic chemical principles within the context of interesting problem-solving scenarios. Students explore two different methods of density analysis and discover the practical uses and limitations of each. The experiment begins with a simple water-displacement exercise using common objects. Students discover problems involving accuracy and precision when calculating the densities of objects that displace very little water. The concept of flotation is introduced next, in which densities are compared, rather than measured directly, to determine the possibility of a common origin between two pieces of evidence. Students compare the densities of two simulated tire samples in 50 percent ethanol. Next, they perform a two-part analysis of glass and polymer fragments obtained from a simulated hit-and-run accident. Nonglass samples are compared using a saturated sodium chloride solution and water, and glass samples are analyzed in a series of bromoform–bromobenzene solutions. Students are able to successfully match five suspect fragments with the appropriate crime scene fragments using these methods.

The Impact of a Corticotectal Impulse on the Awake Superior Colliculus

Corticotectal (CTect) neurons of layer 5 are large and prominent elements of mammalian visual cortex, with thick apical dendrites that ascend to layer 1, "intrinsically bursting" membrane properties, and fast-conducting descending axons that terminate in multiple subcortical domains. These neurons comprise a major output pathway of primary visual cortex, but virtually nothing is known about the synaptic influence of single CTect impulses on the superior colliculus (SC). Here, we examine the distribution of monosynaptic currents generated in the superficial SC by spontaneous impulses of single CTect neurons. We do this by recording the spikes of CTect neurons and the field potentials that they generate through the depths of the SC. Methods of spike-triggered averaging and current source density analysis are then applied to these data. We show, in fully awake rabbits, that single CTect impulses generate potent, fast-rising monosynaptic currents in the SC similar to those generated in sensory cortex by specific thalamic afferents. These currents are focal in depth, precisely retinotopic, and highly dependent on the conduction velocity of the CTect axon. Moreover, we show that CTect synapses, like thalamocortical synapses, suffer a chronic state of depression in awake subjects that is modulated by preceding interspike interval. However, CTect neurons generated few "bursts," and postsynaptic responses in the SC were not significantly influenced by a shift from alert to an inattentive state (indicated by hippocampal EEG). Together, our results suggest that single CTect neurons may resemble thalamocortical neurons in their ability to serve as potent "drivers" of postsynaptic targets.

Preparation, Characterization and H2O2 Selectivity of Hyperbranched Polyimides Containing Triazine

Novel polyimides based on aromatic dianhyride and various hexahydrotriazine monomers were synthesized via two-stage solution polycondensation method. The resulting polyimides were characterized by solubility, viscosity, density, spectroscopic and thermal analysis methods. The results showed that polyimides soluble in polar solvents and had inherent viscosities ranging from 1.92 to 2.32 dL/g. The glass transition temperatures were 315 and 344 ○C, and the 10% weight loss temperatures were above 604 and 628 ○C. Then, polyimide-modified electrodes were prepared for the selective determination of hydrogen peroxide. The electrochemical behavior of the resulting polyimide film electrodes to the electroactive and non-electroactive species such as ascorbic acid, oxalic acid, hydrogen peroxide, lactose, sucrose and urea was examined by CV, DPV and TB techniques. From the obtained findings, it was shown that polyimide-coated electrode (PI-2) was only permitted to hydrogen peroxide among the species examined. As a result, it is claimed that polyimide electrode could be used as a selective membrane for hydrogen peroxide.

EXTENSION OF ENERGY DENSITY ANALYSIS TO TREATING CHEMICAL BONDS IN MOLECULES

We have extended the method of energy density analysis (EDA), originally proposed by Nakai (Chem Phys Lett363:73, 2002), to treat chemical bonds in molecules. The present method, termed "Bond-EDA", partitions the total energy calculated by the Hartree–Fock method not only into atomic regions, but also bond regions. Numerical applications of Bond-EDA are carried out for ethane and ethylene. The C – C and C – H dissociation processes are examined for both molecules. For ethylene, we further investigate the changes of chemical bonds by the excitation from the singlet ground state to the triplet excited state.

Application of wavelet analysis to the study of spatial pattern of morphotectonic lineaments in digital terrain models. A case study

Tectonic faults are often associated with characteristic geomorphological features such as linear valleys, ridgelines and slope breaks that can be identified as lineaments in remotely sensed images or digital terrain models. Lineaments of tectonic origin are often characterised by periodicity and characteristic spatial pattern. Unlike traditional methods of autocorrelation, variogram, lineament density and Fourier analysis, wavelet analysis is capable of capturing and describing both periodicity and spatial pattern of lineaments. In this paper, a case study is shown for the application of wavelet analysis to morphotectonic lineament investigation. Results of wavelet analysis are compared to traditional methods. Although this study involves DEM-derived morphological lineaments, the presented wavelet analysis can be also used for lineaments derived from remotely sensed images. These results hold for this case study and provide a good assessment of the relative abilities of wavelet analysis, but it remains to be seen how effective it is for other data sources, areas and geological terrain.

Issues of effectiveness in empirical methods for describing swelling soils

Swelling soils are a major engineering problem and the establishment of new and fast methods for their identification continues to be a major subject of research. Several engineering methods were here used to obtained indices used in the estimation of swelling potential in a group of soil samples with a wide variation in swelling and to classify them into swelling potential classes. The indices were then reduced through factor analysis to obtain a new swell index that was used to obtain the spectral parameters to best correlate with the index where absorption feature mapping, optical density, and derivative spectral data analysis methods were used to establish these parameters. The spectral parameters found to have high correlations with the swell index were then used to establish statistical empirical models to quantify soil swelling from spectral data. The physical understanding of these spectral parameters was also sought and the results show a close relationship between the clay mineralogy related bound water and hydroxyl spectral features in the soil spectra and the swelling index. The bound water parameters gave positive and the hydroxyl related parameters negative correlations to this index. The results confirm the strong influence of the clay mineralogy on the soil properties.

Fractal analysis of highly volatile markets: an application to technology equities

This paper examines technology equity price series using five self-affine fractal analysis techniques for estimating the Hurst exponent, Mandelbrot–Lévy characteristic exponent, and fractal dimension. Techniques employed are rescaled-range analysis, power-spectral density analysis, roughness-length analysis, the variogram or structure function method, and wavelet analysis. Evidence against efficient valuation supports the multifractal model of asset returns (MMAR) and disconfirms the weak form of the efficient market hypothesis (EMH). Strong evidence is presented for antipersistence of many technology equities, suggesting markets do not price all technology securities efficiently, or equally efficiently.

Continuous two-dimensional current source density analyses of electrophysiological activity in hippocampal slices

The well-studied methods of current source density analysis use the Laplacian transform to identify locations and relative magnitudes of current sources and sinks. The method is typically used in reduced one-dimensional form for electrophysiological measures, due to technical limitations. The present paper outlines a two-dimensional method in which simultaneous samples are recorded from multiple electrodes in an equidistant array, enabling the continuous sensing of current flows in any direction within the plane of the slice. This method reveals spatial aspects of the current sources and sinks that are difficult to discern by other means.

Descriptive econometrics for non‐stationary time series with empirical illustrations

AbstractRecent work by the author on methods of spatial density analysis for time series data with stochastic trends is reviewed. The methods are extended to include processes with deterministic trends, formulae for the mean spatial density are given, and the limits of sample moments of non‐stationary data are shown to take the form of moments with respect to the underlying spatial density, analogous to population moments of a stationary process. The methods are illustrated in some empirical applications and simulations. The empirical applications include macroeconomic data on inflation, financial data on exchange rates and political opinion poll data. It is shown how the methods can be used to measure empirical hazard rates for inflation and deflation. Empirical estimates based on historical US data over the last 60 years indicate that the predominant inflation risks are at low levels (2–6%) and low two‐digit levels (10–12%), and that there is also a significant risk of deflation around the −1% level. Copyright © 2001 John Wiley & Sons, Ltd.

Characterization of Base Periodicities in Protein-Coding Genes

A Fourier Transform of Equal Symbols (FTES) was applied as a spectral density analysis method to identify DNA bases that repeat at any frequency in selected protein-coding genes. The analysis especially focused on identification of bases responsible for the dominant signal at frequency f=1/3 found in all protein-coding genes. The study included homologous sequences from two gene families and multiple unrelated sequences from single organisms. No signal pattern or spectrum specifically characterized either gene family. However, the patterns of bases comprising the signal at f=1/3 suggested the presence of a genome-specific label for protein-coding genes from the same genome. Data suggest that three factors form the informational basis for the signal structure at f=1/3: (1) codon base positional bias; (2) codon preference; and (3) codon arrangement. Quantitative measure of the contribution of each base to the period-3 signal suggests a basis to distinguish protein-coding genes from different organisms. Application of the FTES analysis characterized genes from Escherichia coli as different from the genes from Pseudomonas aeruginosa. Preliminary analyses of genes from these and three other bacteria by artificial neural nets, using FTES parameters, support our suggestion that the period-3 informational structure contains labels for the genomic origins of protein-coding genes. FTES analysis alone or in combination with other informational measures may reveal pathways and processes of gene flow into and through natural systems of microbial cell populations.

Many-electron hyperpolarizability density analysis: Application to the dissociation processof one-dimensionalH2s

A method for density analysis of static polarizabilities (\ensuremath{\alpha}) and second hyperpolarizabilities (\ensuremath{\gamma}) on the basis of the finite-field (FF) many-electron wave packets (MEWP) method is developed and applied to evaluation of the longitudinal \ensuremath{\alpha} and \ensuremath{\gamma} in the dissociation process for a one-dimensional ${\mathrm{H}}_{2}$ model. Remarkable increases in \ensuremath{\alpha} and \ensuremath{\gamma} are observed in the intermediate dissociation region. The internuclear distance where the \ensuremath{\gamma} is maximized is also found to be larger than that where the \ensuremath{\alpha} is maximized. In order to elucidate the characteristics of \ensuremath{\alpha} and \ensuremath{\gamma} in the dissociation process, we extract their classical pictures describing displacements of two-electron configurations by using (hyper)polarizability densities on the two-electron coordinate plane. It is suggested from these classical pictures that the polarization in the ionic structure contributes primarily to the enhancement of (hyper)polarizability in the intermediate dissociation region, while the polarization in the diradical structure causes the decrease of the (hyper)polarizability at a large internuclear distance. This implies that the experimental search for species with chemical bonds in the intermediate correlation regime is important and interesting in relation to the molecular design of nonlinear optical materials.

Size-consistent approach and density analysis of hyperpolarizability: Second hyperpolarizabilities of polymeric systems with and without defects

Various size-consistent approaches to the calculation of molecular hyperpolarizabilities are analyzed based on the double perturbation theory. General equations for the nth-order response property with respect to an external time-independent field are derived on the basis of the Rayleigh–Schrödinger perturbation theory (RSPT) and the coupled-cluster (CC) theory. The corresponding equations for the time-dependent case are also derived by the CC formalism, which is referred to as the time-dependent CC (TDCC) method. In order to clarify the spatial characteristics of polarizability and hyperpolarizability, we present an analysis method using a new concept ‘‘the polarizability and hyperpolarizability densities.’’ As an application of the size-consistent methods, the static second hyperpolarizabilities (γ) of π-conjugated polymeric systems are calculated by the use of the uncoupled (UCHF), and coupled-Hartree–Fock (CHF) methods combined with the semiempirical INDO approximation. Characteristics of γ values calculated for regular polyenes, solitonlike polyenes and donor(D)–acceptor(A) disubstituted polyenes are investigated, particularly in relation to the chain-length effect. Further, we employ γ density analysis method, in which the third derivatives of the Mulliken charge densities against applied electric fields are plotted for exploring the local contributions of the constituent atoms to γ values. Results for the finite polyenes are also extrapolated to an infinity of the chain length to predict the intrinsic γ values per unit carbon–carbon (CC) bond of polymeric chains. Furthermore, the CHF+Mo/ller–Plesset second-order perturbation (MP2) method in the PPP approximation is applied to polymeric systems with larger chain length in order to elucidate the electron correlation effects on the chain-length dependencies of γ values.

Reactant Correlation Effects Study of Hydrogen Isotope Exchange Reaction on Supported Metal Catalysts

ABSTRACTNon-classical results due to reactant correlation effects have been observed in the study of Monte Carlo simulations of the A2 + B2 → 2AB reaction. These simulation results, interpreted by the Pair Density Analysis method and the experimental kinetic studies, may provide an explanation of the early time anomalous kinetic behavior of the catalytic hydrogen isotope exchange reaction exhibited for surface-diffusion limited conditions on alumina supported platinum islands.

IDENTIFICATION AND EVALUATION OF NATURAL PASTURE AND MEADOWLAND FROM REMOTE SENSING IMAGERY

This paper examines the possibilities and limitations of the use of remote sensing imagery in rangeland productivity analysis, by applying landscape indicator methods of image interpretation and optical density analysis to grassland vegetation endemic to a number of different natural habitats. Considerable attention is devoted to a method of identifying different classes of natural fodder land as an outcome of detailed interpretation and mapping of natural-economic regionalization on the basis of joint laboratory-field studies relying upon small-scale space imagery, air photos, and topographic maps. Translated by Edward Torrey, Alexandria, VA 22308 from: G. V. Dobrovol'skiy and V. L. Andronikov, eds., Aerokosmicheskiye metody v pochvovedenii i ikh ispol'zovaniye v sel'skom khozyaystve: sbornik nauchnykh trudov [Remote Sensing Methods in Soil Science and Their Utilization in Agriculture]. Moscow: Nauka, 1990, pp. 201–206.

Current source density analysis of linear and non-linear components of the primate electroretinogram.

1. We have used the method of current source density analysis to locate the generators of harmonic electroretinogram (ERG) responses to contrast-modulated pattern and uniform-field stimuli in the primate retina. 2. Sinusoidal steady-state analysis was used, with a stimulus temporal frequency of 8 Hz. Fundamental and second-harmonic response components were measured for the uniform-field response. The second harmonic of the average of contrast-reversal pattern responses obtained at a series of spatial phases was also determined in the same experiments. In addition, retinal tissue resistance was measured. All of these measurements were obtained at a series of equally spaced depths in the retina. 3. Retinal resistivity was not observed to vary systematically with depth. In addition, any plausible undetected inhomogeneities of resistivity with depth were found to slightly affect the relative magnitudes of estimated current sources and sinks, but to have little effect on their localization. 4. In a given penetration, the phase lag of each harmonic component was relatively constant with depth in most cases; however the magnitude of this phase lag sometimes varied in different penetrations. To compare data from different penetrations, the constant phase lag for each harmonic was estimated, and the response data phase-shifted so as to bring all data into a standard (cosine) phase. 5. The resulting current source density analyses were found to be quite consistent in overall form for different penetrations and in different animals. These data were averaged to obtain a final estimate of the depth profiles for generators of different ERG components. 6. The uniform-field fundamental response was found to have a predominant source-sink pair in the distal half of the retina (receptor layer to outer plexiform layer). The pattern (second-harmonic) response generators had a quite different depth profile, consisting mainly of a source-sink pair in the proximal 20% of the retina (encompassing the nerve fibre layer to the middle of the inner plexiform layer). The uniform-field second-harmonic response showed a current source density (CSD) depth profile with multiple sources/sinks, as if it contained contributions from the other two.

A current source density analysis of field potentials evoked in slices of visual cortex.

The method of one-dimensional current source density (CSD) analysis was applied to field potentials recorded from 350 microns thick slices of the primary visual cortex of rats and cats. Field potentials were elicited by stimulation of the white matter and recorded along trajectories perpendicular to the cortical layers at spatial intervals of 25 to 50 microns. The resulting CSD distributions resembled closely those recorded from the cat visual cortex "in vivo". The responses with the shortest latency were distinct sinks in layers IV and VI probably reflecting monosynaptic EPSP's from specific thalamic afferents. From layer IV activity was relayed along three major routes: 1. to the supragranular layers via strong local connections to layer III and from there via both short and long range connections to layer II, 2. to targets within layer IV, and 3. to layer V. The source distributions suggest that the projections to layers III and II terminate on the proximal and distal segments, respectively, of apical dendrites of layer III pyramidal cells while the projection to layer V contacts the apical dendrites of layer VI pyramidal cells. These results indicate that all the excitatory pathways that are detectable with the CSD technique in the "in vivo" preparation remain intact in 350 micron thick cortical slices. However, in the slice paired pulse stimulation did not lead to a depression of the response to the second stimulus while this is the case "in vivo". This might be due to reduced inhibition in the slice which has been reported by several authors.