Multipartite entanglement indicators based on monogamy relations of n-qubit symmetric states

NASA Astrophysics Data System (ADS)

Liu, Feng; Gao, Fei; Qin, Su-Juan; Xie, Shu-Cui; Wen, Qiao-Yan

2016-02-01

Constructed from Bai-Xu-Wang-class monogamy relations, multipartite entanglement indicators can detect the entanglement not stored in pairs of the focus particle and the other subset of particles. We investigate the k-partite entanglement indicators related to the αth power of entanglement of formation (αEoF) for k ≤ n, αɛ and n-qubit symmetric states. We then show that (1) The indicator based on αEoF is a monotonically increasing function of k. (2) When n is large enough, the indicator based on αEoF is a monotonically decreasing function of α, and then the n-partite indicator based on works best. However, the indicator based on 2 EoF works better when n is small enough.

Isolating spectral cues in amplitude and quasi-frequency modulation discrimination by reducing stimulus duration.

PubMed

Borucki, Ewa; Berg, Bruce G

2017-05-01

This study investigated the psychophysical effects of distortion products in a listening task traditionally used to estimate the bandwidth of phase sensitivity. For a 2000 Hz carrier, estimates of modulation depth necessary to discriminate amplitude modulated (AM) tones and quasi-frequency modulated (QFM) were measured in a two interval forced choice task as a function modulation frequency. Temporal modulation transfer functions were often non-monotonic at modulation frequencies above 300 Hz. This was likely to be due to a spectral cue arising from the interaction of auditory distortion products and the lower sideband of the stimulus complex. When the stimulus duration was decreased from 200 ms to 20 ms, thresholds for low-frequency modulators rose to near-chance levels, whereas thresholds in the region of non-monotonicities were less affected. The decrease in stimulus duration appears to hinder the listener's ability to use temporal cues in order to discriminate between AM and QFM, whereas spectral information derived from distortion product cues appears more resilient. Copyright © 2017. Published by Elsevier B.V.

Enhanced thermoelectric performance of defected silicene nanoribbons

NASA Astrophysics Data System (ADS)

Zhao, W.; Guo, Z. X.; Zhang, Y.; Ding, J. W.; Zheng, X. J.

2016-02-01

Based on non-equilibrium Green's function method, we investigate the thermoelectric performance for both zigzag (ZSiNRs) and armchair (ASiNRs) silicene nanoribbons with central or edge defects. For perfect silicene nanoribbons (SiNRs), it is shown that with its width increasing, the maximum of ZT values (ZTM) decreases monotonously while the phononic thermal conductance increases linearly. For various types of edges and defects, with increasing defect numbers in longitudinal direction, ZTM increases monotonously while the phononic thermal conductance decreases. Comparing with ZSiNRs, defected ASiNRs possess higher thermoelectric performance due to higher Seebeck coefficient and lower thermal conductance. In particular, about 2.5 times enhancement to ZT values is obtained in ASiNRs with edge defects. Our theoretical simulations indicate that by controlling the type and number of defects, ZT values of SiNRs could be enhanced greatly which suggests their very appealing thermoelectric applications.

Epidemic spreading between two coupled subpopulations with inner structures

NASA Astrophysics Data System (ADS)

Ruan, Zhongyuan; Tang, Ming; Gu, Changgui; Xu, Jinshan

2017-10-01

The structure of underlying contact network and the mobility of agents are two decisive factors for epidemic spreading in reality. Here, we study a model consisting of two coupled subpopulations with intra-structures that emphasizes both the contact structure and the recurrent mobility pattern of individuals simultaneously. We show that the coupling of the two subpopulations (via interconnections between them and round trips of individuals) makes the epidemic threshold in each subnetwork to be the same. Moreover, we find that the interconnection probability between two subpopulations and the travel rate are important factors for spreading dynamics. In particular, as a function of interconnection probability, the epidemic threshold in each subpopulation decreases monotonously, which enhances the risks of an epidemic. While the epidemic threshold displays a non-monotonic variation as travel rate increases. Moreover, the asymptotic infected density as a function of travel rate in each subpopulation behaves differently depending on the interconnection probability.

Neural Specificity for Grammatical Operations is Revealed by Content-Independent fMR Adaptation

PubMed Central

Shapiro, Kevin A.; Moo, Lauren R.; Caramazza, Alfonso

2012-01-01

The ability to generate novel sentences depends on cognitive operations that specify the syntactic function of nouns, verbs, and other words retrieved from the mental lexicon. Although neuropsychological studies suggest that such operations rely on neural circuits distinct from those encoding word form and meaning, it has not been possible to characterize this distinction definitively with neuroimaging. We used functional magnetic resonance imaging (fMRI) to show that a brain area engaged in a given grammatical operation can be identified uniquely by a monotonic decrease in activation as that operation is repeated. We applied this methodology to identify areas involved selectively in the operation of inflection of nouns or verbs. By contrast, areas involved in processing word meaning do not show this monotonic adaptation across stimuli. These results are the first to demonstrate adaptation in the fMR signal evoked not by specific stimuli, but by well-defined cognitive linguistic operations. PMID:22347206

Comparison of universal approximators incorporating partial monotonicity by structure.

PubMed

Minin, Alexey; Velikova, Marina; Lang, Bernhard; Daniels, Hennie

2010-05-01

Neural networks applied in control loops and safety-critical domains have to meet more requirements than just the overall best function approximation. On the one hand, a small approximation error is required; on the other hand, the smoothness and the monotonicity of selected input-output relations have to be guaranteed. Otherwise, the stability of most of the control laws is lost. In this article we compare two neural network-based approaches incorporating partial monotonicity by structure, namely the Monotonic Multi-Layer Perceptron (MONMLP) network and the Monotonic MIN-MAX (MONMM) network. We show the universal approximation capabilities of both types of network for partially monotone functions. On a number of datasets, we investigate the advantages and disadvantages of these approaches related to approximation performance, training of the model and convergence. 2009 Elsevier Ltd. All rights reserved.

Testing Manifest Monotonicity Using Order-Constrained Statistical Inference

ERIC Educational Resources Information Center

Tijmstra, Jesper; Hessen, David J.; van der Heijden, Peter G. M.; Sijtsma, Klaas

2013-01-01

Most dichotomous item response models share the assumption of latent monotonicity, which states that the probability of a positive response to an item is a nondecreasing function of a latent variable intended to be measured. Latent monotonicity cannot be evaluated directly, but it implies manifest monotonicity across a variety of observed scores,…

Dissipative properties of hot and dense hadronic matter in an excluded-volume hadron resonance gas model

NASA Astrophysics Data System (ADS)

Kadam, Guru Prakash; Mishra, Hiranmaya

2015-09-01

We estimate dissipative properties, viz., shear and bulk viscosities of hadronic matter using relativistic Boltzmann equation in relaxation time approximation within the framework of excluded-volume hadron resonance gas (EHRG) model. We find that at zero baryon chemical potential the shear viscosity to entropy ratio (η /s ) decreases with temperature while at finite baryon chemical potential this ratio shows the same behavior as a function of temperature but reaches close to the Kovtun-Son-Starinets (KSS) bound. Further along the chemical freezeout curve, ratio η /s is almost constant apart from small initial monotonic rise. This observation may have some relevance to the experimental finding that the differential elliptic flow of charged hadrons does not change considerably at lower center-of-mass energy. We further find that bulk viscosity to entropy density (ζ /s ) decreases with temperature while this ratio has higher value at finite baryon chemical potential at higher temperature. Along the freezeout curve ζ /s decreases monotonically at lower center-of-mass energy and then saturates.

Maximum value of the pulse energy of a passively Q-switched laser as a function of the pump power.

PubMed

Li, Jianlang; Ueda, Ken-ichi; Dong, Jun; Musha, Mitsuru; Shirakawa, Akira

2006-07-20

The finite recovery time Ts of the bleached absorber is presented as one of the possible mechanisms accounting for the increase-maximum-decrease in pulse energy E with the pumping rate Wp in cw-pumped passively Q-switched solid-state lasers, by analytically evaluating the sign of the derivative partial differentialE/ partial differentialWP. The results show that, in the low pump regime (T>Ts, T is the interpulse period), the initial population density ni remains constant, the final population density nf decreases with Wp, and this results in a monotonic increase of E with Wp. In the high pump regime (T

The role of the indoor environment: Residential determinants of allergy, asthma and pulmonary function in children from a US-Mexico border community.

PubMed

Svendsen, Erik R; Gonzales, Melissa; Commodore, Adwoa

2018-03-01

The El Paso Children's Health Study examined environmental risk factors for allergy and asthma among fourth and fifth grade schoolchildren living in a major United States-Mexico border city. Complete questionnaire information was available for 5210 children, while adequate pulmonary function data were available for a subset of 1874. Herein we studied indoor environmental health risk factors for allergy and asthma. Several indoor environmental risk factors were associated with allergy and asthma. In particular, we found that ant and spider pest problems, pet dogs, fireplace heat, central air conditioning, humidifier use, and cooking with gas stoves were positively associated with both allergy and asthma prevalence. With regards to asthma severity, our analysis indicated that exposure to pet dogs increased monotonically with increasing asthma severity while the lack of any heat source and gas stove use for cooking decreased monotonically with increasing asthma severity. Lung function also decreased among children who lived in homes with reported cockroach pest problem in the past year without concurrent use of pesticides. These effects on pulmonary function were present even after excluding children with a current physician's diagnosis of asthma. Clinicians and public health professionals may need to look closely at the contribution of these indoor risk factors on pulmonary health and quality of life among susceptible populations. Copyright © 2017 Elsevier B.V. All rights reserved.

A fiber-optic technique for the measurement of contact angle in a clearance-fit pin-loaded hole

NASA Technical Reports Server (NTRS)

Prabhakaran, R.; Naik, R. A.

1987-01-01

A fiber-optic technique for measuring contact angle during pin loading of a specimen is proposed. The experimental design and procedures for loading a 49.8-mm-diameter instrumented pin into an quasi-isotropic graphite-epoxy specimen are described. The optical fiber was located just above the surface of the pin outer diameter in order to obtain accurate pin-hole contact-angle measurements at increasing load levels. The movement of the optical fiber through the no-contact, contact, and no-contact regions is discussed; the photodiode output decreased monotonically as the fiber moved from the no-contact to the contact region and then decreased monotonically as the fiber moved from the contact region to the no-contact region. Variations in the contact angle measurements are examined as function of applied load level. The measurements are compared to contact angle values obtained using a finite element analysis and an electrical technique; it is determined that the data correlate well.

The period function of the generalized Lotka-Volterra centers

NASA Astrophysics Data System (ADS)

Villadelprat, J.

2008-05-01

The present paper deals with the period function of the quadratic centers. In the literature different terminologies are used to classify these centers, but essentially there are four families: Hamiltonian, reversible , codimension four Q4 and generalized Lotka-Volterra systems . Chicone [C. Chicone, Review in MathSciNet, Ref. 94h:58072] conjectured that the reversible centers have at most two critical periods, and that the centers of the three other families have a monotonic period function. With regard to the second part of this conjecture, only the monotonicity of the Hamiltonian and Q4 families [W.A. Coppel, L. Gavrilov, The period function of a Hamiltonian quadratic system, Differential Integral Equations 6 (1993) 1357-1365; Y. Zhao, The monotonicity of period function for codimension four quadratic system Q4, J. Differential Equations 185 (2002) 370-387] has been proved. Concerning the family, no substantial progress has been made since the middle 80s, when several authors showed independently the monotonicity of the classical Lotka-Volterra centers [F. Rothe, The periods of the Volterra-Lokta system, J. Reine Angew. Math. 355 (1985) 129-138; R. Schaaf, Global behaviour of solution branches for some Neumann problems depending on one or several parameters, J. Reine Angew. Math. 346 (1984) 1-31; J. Waldvogel, The period in the Lotka-Volterra system is monotonic, J. Math. Anal. Appl. 114 (1986) 178-184]. By means of the first period constant one can easily conclude that the period function of the centers in the family is monotone increasing near the inner boundary of its period annulus (i.e., the center itself). Thus, according to Chicone's conjecture, it should be also monotone increasing near the outer boundary, which in the Poincaré disc is a polycycle. In this paper we show that this is true. In addition we prove that, except for a zero measure subset of the parameter plane, there is no bifurcation of critical periods from the outer boundary. Finally we show that the period function is globally (i.e., in the whole period annulus) monotone increasing in two other cases different from the classical one.

Effects of rare earth ionic doping on microstructures and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

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

Xue, Renzhong; Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002; Chen, Zhenping, E-mail: xrzbotao@163.com

2015-06-15

Graphical abstract: The dielectric constant decreases monotonically with reduced RE doping ion radius and is more frequency independent compared with that of pure CCTO sample. - Highlights: • The mean grain sizes decrease monotonically with reduced RE doping ionic radius. • Doping gives rise to the monotonic decrease of ϵ{sub r} with reduced RE ionic radius. • The nonlinear coefficient and breakdown field increase with RE ionic doping. • α of all the samples is associated with the potential barrier width rather than Φ{sub b}. - Abstract: Ca{sub 1–x}R{sub x}Cu{sub 3}Ti{sub 4}O{sub 12}(R = La, Nd, Eu, Gd, Er; xmore » = 0 and 0.005) ceramics were prepared by the conventional solid-state method. The influences of rare earth (RE) ion doping on the microstructure, dielectric and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramics were investigated systematically. Single-phase formation is confirmed by XRD analyses. The mean grain size decreases monotonically with reduced RE ion radius. The EDS results reveal that RE ionic doping reduces Cu-rich phase segregation at the grain boundaries (GBs). Doping gives rise to the monotonic decrease of dielectric constant with reduced RE ionic radius but significantly improves stability with frequency. The lower dielectric loss of doped samples is obtained due to the increase of GB resistance. In addition, the nonlinear coefficient and breakdown field increase with RE ionic doping. Both the fine grains and the enhancement of potential barrier at GBs are responsible for the improvement of the nonlinear current–voltage properties in doped CCTO samples.« less

Specific non-monotonous interactions increase persistence of ecological networks.

PubMed

Yan, Chuan; Zhang, Zhibin

2014-03-22

The relationship between stability and biodiversity has long been debated in ecology due to opposing empirical observations and theoretical predictions. Species interaction strength is often assumed to be monotonically related to population density, but the effects on stability of ecological networks of non-monotonous interactions that change signs have not been investigated previously. We demonstrate that for four kinds of non-monotonous interactions, shifting signs to negative or neutral interactions at high population density increases persistence (a measure of stability) of ecological networks, while for the other two kinds of non-monotonous interactions shifting signs to positive interactions at high population density decreases persistence of networks. Our results reveal a novel mechanism of network stabilization caused by specific non-monotonous interaction types through either increasing stable equilibrium points or reducing unstable equilibrium points (or both). These specific non-monotonous interactions may be important in maintaining stable and complex ecological networks, as well as other networks such as genes, neurons, the internet and human societies.

A note on monotonicity of item response functions for ordered polytomous item response theory models.

PubMed

Kang, Hyeon-Ah; Su, Ya-Hui; Chang, Hua-Hua

2018-03-08

A monotone relationship between a true score (τ) and a latent trait level (θ) has been a key assumption for many psychometric applications. The monotonicity property in dichotomous response models is evident as a result of a transformation via a test characteristic curve. Monotonicity in polytomous models, in contrast, is not immediately obvious because item response functions are determined by a set of response category curves, which are conceivably non-monotonic in θ. The purpose of the present note is to demonstrate strict monotonicity in ordered polytomous item response models. Five models that are widely used in operational assessments are considered for proof: the generalized partial credit model (Muraki, 1992, Applied Psychological Measurement, 16, 159), the nominal model (Bock, 1972, Psychometrika, 37, 29), the partial credit model (Masters, 1982, Psychometrika, 47, 147), the rating scale model (Andrich, 1978, Psychometrika, 43, 561), and the graded response model (Samejima, 1972, A general model for free-response data (Psychometric Monograph no. 18). Psychometric Society, Richmond). The study asserts that the item response functions in these models strictly increase in θ and thus there exists strict monotonicity between τ and θ under certain specified conditions. This conclusion validates the practice of customarily using τ in place of θ in applied settings and provides theoretical grounds for one-to-one transformations between the two scales. © 2018 The British Psychological Society.

Evidence for Direct Retrieval of Relative Quantity Information in a Quantity Judgment Task: Decimals, Integers, and the Role of Physical Similarity

ERIC Educational Resources Information Center

Cohen, Dale J.

2010-01-01

Participants' reaction times (RTs) in numerical judgment tasks in which one must determine which of 2 numbers is greater generally follow a monotonically decreasing function of the numerical distance between the two presented numbers. Here, I present 3 experiments in which the relative influences of numerical distance and physical similarity are…

Multistability of memristive Cohen-Grossberg neural networks with non-monotonic piecewise linear activation functions and time-varying delays.

PubMed

Nie, Xiaobing; Zheng, Wei Xing; Cao, Jinde

2015-11-01

The problem of coexistence and dynamical behaviors of multiple equilibrium points is addressed for a class of memristive Cohen-Grossberg neural networks with non-monotonic piecewise linear activation functions and time-varying delays. By virtue of the fixed point theorem, nonsmooth analysis theory and other analytical tools, some sufficient conditions are established to guarantee that such n-dimensional memristive Cohen-Grossberg neural networks can have 5(n) equilibrium points, among which 3(n) equilibrium points are locally exponentially stable. It is shown that greater storage capacity can be achieved by neural networks with the non-monotonic activation functions introduced herein than the ones with Mexican-hat-type activation function. In addition, unlike most existing multistability results of neural networks with monotonic activation functions, those obtained 3(n) locally stable equilibrium points are located both in saturated regions and unsaturated regions. The theoretical findings are verified by an illustrative example with computer simulations. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Neglect of Monotone Comparative Statics Methods

ERIC Educational Resources Information Center

Tremblay, Carol Horton; Tremblay, Victor J.

2010-01-01

Monotone methods enable comparative static analysis without the restrictive assumptions of the implicit-function theorem. Ease of use and flexibility in solving comparative static and game-theory problems have made monotone methods popular in the economics literature and in graduate courses, but they are still absent from undergraduate…

Alterable Magnetic Gratings for Fiber Optic Switching.

DTIC Science & Technology

1982-12-01

monotonically decreasing function as X moves into the infrared from the visible. The Faraday rotation of bismuth garnet samples including the new large... photodector giving as fast a response as possible while still providing usable signal levels, measure the detector response * using the electro-optic...icity. Normally a stripe domain array is configured as a linear grating. In-plane magnetic fields can rotate the grating as well as alter the periodicity

Different Aspects of the Monotonicity of a Function

ERIC Educational Resources Information Center

Tossavainen, Timo; Haukkanen, Pentti; Pesonen, Martti

2013-01-01

In this paper, we investigate which aspects are overriding in the concept images of monotonicity of Finnish tertiary mathematics students, i.e., on which aspects of monotonicity they base their argument in different types of exercises related to that concept. Further, we examine the relationship between the quality of principal aspects and the…

Electrostatic charge on a dust size distribution in a plasma. [in interplanetary space

NASA Technical Reports Server (NTRS)

Houpis, Harry L. F.; Whipple, Elden C., Jr.

1987-01-01

The capacitance of a grain immersed in a steady state plasma containing a size distribution of dust particles is studied. The grain charge is determined by assuming the equilibrium potential has been obtained by a simple balance of electron and ion collection currents. It is shown that the validity of the analytical treatment given here for the linearized Poisson equation is confined to a certain region of space. Within this region and starting at very small plasma Debye length lambda(D), the capacitance at first exhibits a monotonic increase with increasing lambda(D). The capacitance eventually reaches a maximum, followed by a monotonic decrease. The charge density of the dust in the plasma is found to be only a function of the lambda(D); there is no significant dependence on the interparticle spacing.

The humpbacked species richness-curve: A contingent rule for community ecology

USGS Publications Warehouse

Graham, John H.; Duda, Jeffrey J.

2011-01-01

Functional relationships involving species richness may be unimodal, monotonically increasing, monotonically decreasing, bimodal, multimodal, U-shaped, or with no discernable pattern. The unimodal relationships are the most interesting because they suggest dynamic, nonequilibrium community processes. For that reason, they are also contentious. In this paper, we provide a wide-ranging review of the literature on unimodal (humpbacked) species richness-relationships. Though not as widespread as previously thought, unimodal patterns of species richness are often associated with disturbance, predation and herbivory, productivity, spatial heterogeneity, environmental gradients, time, and latitude. These unimodal patterns are contingent on organism and environment; we examine unimodal species richness-curves involving plants, invertebrates, vertebrates, plankton, and microbes in marine, lacustrine, and terrestrial habitats. A goal of future research is to understand the contingent patterns and the complex, interacting processes that generate them.

Viscosities of Fe Ni, Fe Co and Ni Co binary melts

NASA Astrophysics Data System (ADS)

Sato, Yuzuru; Sugisawa, Koji; Aoki, Daisuke; Yamamura, Tsutomu

2005-02-01

Viscosities of three binary molten alloys consisting of the iron group elements, Fe, Ni and Co, have been measured by using an oscillating cup viscometer over the entire composition range from liquidus temperatures up to 1600 °C with high precision and excellent reproducibility. The viscosities measured showed good Arrhenius linearity for all the compositions. The viscosities of Fe, Ni and Co as a function of temperature are as follows: \\eqalign{ & \\log \\eta={-}0.6074 + 2493/T\\qquad for\\quad Fe\\\\ & \\log \\eta={-}0.5695 + 2157/T\\qquad for\\quad Ni \\\\ & \\log \\eta={-}0.6620 + 2430/T\\qquad for\\quad Co.} The isothermal viscosities of Fe-Ni and Fe-Co binary melts increase monotonically with increasing Fe content. On the other hand, in Ni-Co binary melt, the isothermal viscosity decreases slightly and then increases with increasing Co. The activation energy of Fe-Co binary melt increased slightly on mixing, and those of Fe-Ni and Ni-Co melts decreased monotonically with increasing Ni content. The above behaviour is discussed based on the thermodynamic properties of the alloys.

Monotonicity of fitness landscapes and mutation rate control.

PubMed

Belavkin, Roman V; Channon, Alastair; Aston, Elizabeth; Aston, John; Krašovec, Rok; Knight, Christopher G

2016-12-01

A common view in evolutionary biology is that mutation rates are minimised. However, studies in combinatorial optimisation and search have shown a clear advantage of using variable mutation rates as a control parameter to optimise the performance of evolutionary algorithms. Much biological theory in this area is based on Ronald Fisher's work, who used Euclidean geometry to study the relation between mutation size and expected fitness of the offspring in infinite phenotypic spaces. Here we reconsider this theory based on the alternative geometry of discrete and finite spaces of DNA sequences. First, we consider the geometric case of fitness being isomorphic to distance from an optimum, and show how problems of optimal mutation rate control can be solved exactly or approximately depending on additional constraints of the problem. Then we consider the general case of fitness communicating only partial information about the distance. We define weak monotonicity of fitness landscapes and prove that this property holds in all landscapes that are continuous and open at the optimum. This theoretical result motivates our hypothesis that optimal mutation rate functions in such landscapes will increase when fitness decreases in some neighbourhood of an optimum, resembling the control functions derived in the geometric case. We test this hypothesis experimentally by analysing approximately optimal mutation rate control functions in 115 complete landscapes of binding scores between DNA sequences and transcription factors. Our findings support the hypothesis and find that the increase of mutation rate is more rapid in landscapes that are less monotonic (more rugged). We discuss the relevance of these findings to living organisms.

Computation of non-monotonic Lyapunov functions for continuous-time systems

NASA Astrophysics Data System (ADS)

Li, Huijuan; Liu, AnPing

2017-09-01

In this paper, we propose two methods to compute non-monotonic Lyapunov functions for continuous-time systems which are asymptotically stable. The first method is to solve a linear optimization problem on a compact and bounded set. The proposed linear programming based algorithm delivers a CPA1

Estradiol selectively enhances auditory function in avian forebrain neurons

PubMed Central

Caras, Melissa L.; O’Brien, Matthew; Brenowitz, Eliot A.; Rubel, Edwin W

2012-01-01

Sex steroids modulate vertebrate sensory processing, but the impact of circulating hormone levels on forebrain function remains unclear. We tested the hypothesis that circulating sex steroids modulate single-unit responses in the avian telencephalic auditory nucleus, field L. We mimicked breeding or non-breeding conditions by manipulating plasma 17β-estradiol levels in wild-caught female Gambel’s white-crowned sparrows (Zonotrichia leucophrys gambelii). Extracellular responses of single neurons to tones and conspecific songs presented over a range of intensities revealed that estradiol selectively enhanced auditory function in cells that exhibited monotonic rate-level functions to pure tones. In these cells, estradiol treatment increased spontaneous and maximum evoked firing rates, increased pure tone response strengths and sensitivity, and expanded the range of intensities over which conspecific song stimuli elicited significant responses. Estradiol did not significantly alter the sensitivity or dynamic ranges of cells that exhibited non-monotonic rate-level functions. Notably, there was a robust correlation between plasma estradiol concentrations in individual birds and physiological response properties in monotonic, but not non-monotonic neurons. These findings demonstrate that functionally distinct classes of anatomically overlapping forebrain neurons are differentially regulated by sex steroid hormones in a dose-dependent manner. PMID:23223283

Dependence of the subharmonic signal from contrast agent microbubbles on ambient pressure: A theoretical analysis.

PubMed

Jiménez-Fernández, J

2018-01-01

This paper investigates the dependence of the subharmonic response in a signal scattered by contrast agent microbubbles on ambient pressure to provide quantitative estimations of local blood pressure. The problem is formulated by assuming a gas bubble encapsulated by a shell of finite thickness with dynamic behavior modeled by a nonlinear viscoelastic constitutive equation. For ambient overpressure compatible with the clinical range, the acoustic pressure intervals where the subharmonic signal may be detected (above the threshold for the onset and below the limit value for the first chaotic transition) are determined. The analysis shows that as the overpressure is increased, all harmonic components are displaced to higher frequencies. This displacement is significant for the subharmonic of order 1/2 and explains the increase or decrease in the subharmonic amplitude with ambient pressure described in previous works. Thus, some questions related to the monotonic dependence of the subharmonic amplitude on ambient pressure are clarified. For different acoustic pressures, quantitative conditions for determining the intervals where the subharmonic amplitude is a monotonic or non-monotonic function of the ambient pressure are provided. Finally, the influence of the ambient pressure on the subharmonic resonance frequency is analyzed.

Evolution of Microstructure in a Nickel-based Superalloy as a Function of Ageing Time

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

Chen, Wei-Ren; Smith, Gregory Scott; Porcar, L.

2011-01-01

An experimental investigation, combining synchrotron X-ray powder diffraction, small-angle neutron-scattering, and transmission electron microscopy, has been undertaken to study the microstructure of nanoprecipitates in a nickel-based superalloy. Upon increasing the ageing time during a heat-treatment process, the average size of the precipitates first decreases before changing to a monotonical growth stage. Possible reasons for this observed structural evolution, which is predicted thermodynamically, are suggested.

Excitation-Power Dependence of the Near Band-Edge PL Spectra of CdMnTe with High Mn Concentrations

NASA Astrophysics Data System (ADS)

Hwang, Younghun; Um, Youngho; Park, Hyoyeol

2011-12-01

Temperature and excitation power dependences of photoluminescence (PL) measurements were studied for the CdMnTe crystal grown by the vertical Bridgman method. The near band-edge and intra-Mn2+ emissions were investigated as a function of temperature. The observed band-edge peak of the PL spectrum showed a clear blue-shift with decreasing temperature. However, the peak energy of the intra-Mn2+ transition did not decrease monotonically with changing temperature, as can be seen above 70 K. With increasing the excitation power, the intensity of the emission peak was increased.

Exploring social welfare functions and violation of monotonicity: an example from inequalities in health.

PubMed

Abasolo, Ignacio; Tsuchiya, Aki

2004-03-01

The social welfare function (SWF) has been used within the economics literature, to study trade-offs between equality and efficiency. These SWFs are characterised by properties determined by traditional welfare economics. One of these properties, the monotonicity principle is explored in this paper. In the context of health there may be occasions when the monotonicity principle is violated as there may be circumstances where distributional issues dominate efficiency concerns. When this is the case, conventional SWFs are not flexible enough to represent such social preferences. Therefore, we propose a SWF with an alternative specification, which is general enough to accommodate preferences that are not necessarily monotonic. A survey of the Spanish general public was undertaken to estimate preferences regarding equality in health, relative to efficiency in health. The results (with 973 usable responses) give strong support to the existence of public preferences which violate the monotonicity principle, and thus to the usefulness of the alternative specification proposed here.

Mills' ratio

NASA Astrophysics Data System (ADS)

Baricz, Árpád

2008-04-01

In this paper we study the monotonicity properties of some functions involving the Mills' ratio of the standard normal law. From these we deduce some new functional inequalities involving the Mills' ratio, and we show that the Mills' ratio is strictly completely monotonic. At the end of this paper we present some Turán-type inequalities for Mills' ratio.

Compact stars

NASA Astrophysics Data System (ADS)

Estevez-Delgado, Gabino; Estevez-Delgado, Joaquin

2018-05-01

An analysis and construction is presented for a stellar model characterized by two parameters (w, n) associated with the compactness ratio and anisotropy, respectively. The reliability range for the parameter w ≤ 1.97981225149 corresponds with a compactness ratio u ≤ 0.2644959374, the density and pressures are positive, regular and monotonic decrescent functions, the radial and tangential speed of sound are lower than the light speed, moreover, than the plausible stability. The behavior of the speeds of sound are determinate for the anisotropy parameter n, admitting a subinterval where the speeds are monotonic crescent functions and other where we have monotonic decrescent functions for the same speeds, both cases describing a compact object that is also potentially stable. In the bigger value for the observational mass M = 2.05 M⊙ and radii R = 12.957 Km for the star PSR J0348+0432, the model indicates that the maximum central density ρc = 1.283820319 × 1018 Kg/m3 corresponds to the maximum value of the anisotropy parameter and the radial and tangential speed of the sound are monotonic decrescent functions.

Modeling subharmonic response from contrast microbubbles as a function of ambient static pressure

PubMed Central

Katiyar, Amit; Sarkar, Kausik; Forsberg, Flemming

2011-01-01

Variation of subharmonic response from contrast microbubbles with ambient pressure is numerically investigated for non-invasive monitoring of organ-level blood pressure. Previously, several contrast microbubbles both in vitro and in vivo registered approximately linear (5–15 dB) subharmonic response reduction with 188 mm Hg change in ambient pressure. In contrast, simulated subharmonic response from a single microbubble is seen here to either increase or decrease with ambient pressure. This is shown using the code BUBBLESIM for encapsulated microbubbles, and then the underlying dynamics is investigated using a free bubble model. The ratio of the excitation frequency to the natural frequency of the bubble is the determining parameter—increasing ambient pressure increases natural frequency thereby changing this ratio. For frequency ratio below a lower critical value, increasing ambient pressure monotonically decreases subharmonic response. Above an upper critical value of the same ratio, increasing ambient pressure increases subharmonic response; in between, the subharmonic variation is non-monotonic. The precise values of frequency ratio for these three different trends depend on bubble radius and excitation amplitude. The modeled increase or decrease of subharmonic with ambient pressure, when one happens, is approximately linear only for certain range of excitation levels. Possible reasons for discrepancies between model and previous experiments are discussed. PMID:21476688

Some properties of the Catalan-Qi function related to the Catalan numbers.

PubMed

Qi, Feng; Mahmoud, Mansour; Shi, Xiao-Ting; Liu, Fang-Fang

2016-01-01

In the paper, the authors find some properties of the Catalan numbers, the Catalan function, and the Catalan-Qi function which is a generalization of the Catalan numbers. Concretely speaking, the authors present a new expression, asymptotic expansions, integral representations, logarithmic convexity, complete monotonicity, minimality, logarithmically complete monotonicity, a generating function, and inequalities of the Catalan numbers, the Catalan function, and the Catalan-Qi function. As by-products, an exponential expansion and a double inequality for the ratio of two gamma functions are derived.

Influence of temper condition on the nonlinear stress-strain behavior of boron-aluminum

NASA Technical Reports Server (NTRS)

Kennedy, J. M.; Herakovich, E. T.; Tenney, D. R.

1977-01-01

The influence of temper condition on the tensile and compressive stress-strain behavior for six boron-aluminum laminates was investigated. In addition to monotonic tension and compression tests, tension-tension, compression-compression, and tension--compression tests were conducted to study the effects of cyclic loading. Tensile strength results are a function of the laminate configuration; unidirectional laminates were affected considerably more than other laminates with some strength values increasing and others decreasing.

Monotonic sequences related to zeros of Bessel functions

NASA Astrophysics Data System (ADS)

Lorch, Lee; Muldoon, Martin

2008-12-01

In the course of their work on Salem numbers and uniform distribution modulo 1, A. Akiyama and Y. Tanigawa proved some inequalities concerning the values of the Bessel function J 0 at multiples of π, i.e., at the zeros of J 1/2. This raises the question of inequalities and monotonicity properties for the sequences of values of one cylinder function at the zeros of another such function. Here we derive such results by differential equations methods.

Aerosol microphysical and radiative effects on continental cloud ensembles

NASA Astrophysics Data System (ADS)

Wang, Yuan; Vogel, Jonathan M.; Lin, Yun; Pan, Bowen; Hu, Jiaxi; Liu, Yangang; Dong, Xiquan; Jiang, Jonathan H.; Yung, Yuk L.; Zhang, Renyi

2018-02-01

Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. In this study, an aerosol-aware WRF model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the US Southern Great Plains. Three simulated cloud ensembles include a low-pressure deep convective cloud system, a collection of less-precipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by several ground-based measurements. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not influence the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with a prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. The simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity (typically less than 2%) to aerosol perturbations, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type.

Drivers' misjudgement of vigilance state during prolonged monotonous daytime driving.

PubMed

Schmidt, Eike A; Schrauf, Michael; Simon, Michael; Fritzsche, Martin; Buchner, Axel; Kincses, Wilhelm E

2009-09-01

To investigate the effects of monotonous daytime driving on vigilance state and particularly the ability to judge this state, a real road driving study was conducted. To objectively assess vigilance state, performance (auditory reaction time) and physiological measures (EEG: alpha spindle rate, P3 amplitude; ECG: heart rate) were recorded continuously. Drivers judged sleepiness, attention to the driving task and monotony retrospectively every 20 min. Results showed that prolonged daytime driving under monotonous conditions leads to a continuous reduction in vigilance. Towards the end of the drive, drivers reported a subjectively improved vigilance state, which was contrary to the continued decrease in vigilance as indicated by all performance and physiological measures. These findings indicate a lack of self-assessment abilities after approximately 3h of continuous monotonous daytime driving.

Testing manifest monotonicity using order-constrained statistical inference.

PubMed

Tijmstra, Jesper; Hessen, David J; van der Heijden, Peter G M; Sijtsma, Klaas

2013-01-01

Most dichotomous item response models share the assumption of latent monotonicity, which states that the probability of a positive response to an item is a nondecreasing function of a latent variable intended to be measured. Latent monotonicity cannot be evaluated directly, but it implies manifest monotonicity across a variety of observed scores, such as the restscore, a single item score, and in some cases the total score. In this study, we show that manifest monotonicity can be tested by means of the order-constrained statistical inference framework. We propose a procedure that uses this framework to determine whether manifest monotonicity should be rejected for specific items. This approach provides a likelihood ratio test for which the p-value can be approximated through simulation. A simulation study is presented that evaluates the Type I error rate and power of the test, and the procedure is applied to empirical data.

On the Use of a Cumulative Distribution as a Utility Function in Educational or Employment Selection.

DTIC Science & Technology

1981-02-01

monotonic increasing function of true ability or performance score. A cumulative probability function is * then very convenient for describiny; one’s...possible outcomes such as test scores, grade-point averages or other common outcome variables. Utility is usually a monotonic increasing function of true ...r(0) is negative for 8 <i and positive for 0 > M, U(o) is risk-prone for low 0 values and risk-averse for high 0 values. This property is true for

Measuring monotony in two-dimensional samples

NASA Astrophysics Data System (ADS)

Kachapova, Farida; Kachapov, Ilias

2010-04-01

This note introduces a monotony coefficient as a new measure of the monotone dependence in a two-dimensional sample. Some properties of this measure are derived. In particular, it is shown that the absolute value of the monotony coefficient for a two-dimensional sample is between |r| and 1, where r is the Pearson's correlation coefficient for the sample; that the monotony coefficient equals 1 for any monotone increasing sample and equals -1 for any monotone decreasing sample. This article contains a few examples demonstrating that the monotony coefficient is a more accurate measure of the degree of monotone dependence for a non-linear relationship than the Pearson's, Spearman's and Kendall's correlation coefficients. The monotony coefficient is a tool that can be applied to samples in order to find dependencies between random variables; it is especially useful in finding couples of dependent variables in a big dataset of many variables. Undergraduate students in mathematics and science would benefit from learning and applying this measure of monotone dependence.

Positron Lifetime Study on the As-Prepared Cd-Doped Pb-1212 Superconductive Oxides

NASA Astrophysics Data System (ADS)

Zhou, X. Y.; Zhou, X. Y.; Zhao, W. C.; Jin, H.; Cao, L. Z.; Zhai, L. H.; Han, R. D.

1997-12-01

The positron lifetime as a function of the Cd content x was measured for the as-prepared samples of (Pb1 - xCdx)Sr2(Y0.5Ca0.5)Cu2Oy. A constant long-lived lifetime was observed for all samples. The intensity of the long-lived lifetimes has an obvious decrease starting at x = 0.3 and indicated the existence of an impurity phase in the sample with x = 0.3. The monotonous decrease of the bulk lifetime for the single-phase samples implies that Cd mainly substitutes for Pb. The changes of the microstructure with Cd content were discussed.

Collective behaviors of suprachiasm nucleus neurons under different light—dark cycles

NASA Astrophysics Data System (ADS)

Gu, Chang-Gui; Zhang, Xin-Hua; Liu, Zong-Hua

2014-07-01

The principal circadian clock in the suprachiasm nucleus (SCN) regulates the circadian rhythm of physiological and behavioral activities of mammals. Except for the normal function of the circadian rhythm, the ensemble of SCN neurons may show two collective behaviors, i.e., a free running period in the absence of a light—dark cycle and an entrainment ability to an external T cycle. Experiments show that both the free running periods and the entrainment ranges may vary from one species to another and can be seriously influenced by the coupling among the SCN neurons. We here review the recent progress on how the heterogeneous couplings influence these two collective behaviors. We will show that in the case of homogeneous coupling, the free running period increases monotonically while the entrainment range decreases monotonically with the increase of the coupling strength. While in the case of heterogenous coupling, the dispersion of the coupling strength plays a crucial role. It has been found that the free running period decreases with the increase of the dispersion while the entrainment ability is enhanced by the dispersion. These findings provide new insights into the mechanism of the circadian clock in the SCN.

Experimental and Theoretical Investigations of Phonation Threshold Pressure as a Function of Vocal Fold Elongation

PubMed Central

Tao, Chao; Regner, Michael F.; Zhang, Yu; Jiang, Jack J.

2014-01-01

Summary The relationship between the vocal fold elongation and the phonation threshold pressure (PTP) was experimentally and theoretically investigated. The PTP values of seventeen excised canine larynges with 0% to 15% bilateral vocal fold elongations in 5% elongation steps were measured using an excised larynx phonation system. It was found that twelve larynges exhibited a monotonic relationship between PTP and elongation; in these larynges, the 0% elongation condition had the lowest PTP. Five larynges exhibited a PTP minimum at 5% elongation. To provide a theoretical explanation of these phenomena, a two-mass model was modified to simulate vibration of the elongated vocal folds. Two pairs of longitudinal springs were used to represent the longitudinal elastin in the vocal folds. This model showed that when the vocal folds were elongated, the increased longitudinal tension would increase the PTP value and the increased vocal fold length would decrease the PTP value. The antagonistic effects contributed by these two factors were found to be able to cause either a monotonic or a non-monotonic relationship between PTP and elongation, which were consistent with experimental observations. Because PTP describes the ease of phonation, this study suggests that there may exist a nonzero optimal vocal fold elongation for the greatest ease for phonation in some larynges. PMID:25530744

An Unconditionally Monotone C 2 Quartic Spline Method with Nonoscillation Derivatives

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

Yao, Jin; Nelson, Karl E.

Here, a one-dimensional monotone interpolation method based on interface reconstruction with partial volumes in the slope-space utilizing the Hermite cubic-spline, is proposed. The new method is only quartic, however is C 2 and unconditionally monotone. A set of control points is employed to constrain the curvature of the interpolation function and to eliminate possible nonphysical oscillations in the slope space. An extension of this method in two-dimensions is also discussed.

An Unconditionally Monotone C 2 Quartic Spline Method with Nonoscillation Derivatives

DOE PAGES

Yao, Jin; Nelson, Karl E.

2018-01-24

Here, a one-dimensional monotone interpolation method based on interface reconstruction with partial volumes in the slope-space utilizing the Hermite cubic-spline, is proposed. The new method is only quartic, however is C 2 and unconditionally monotone. A set of control points is employed to constrain the curvature of the interpolation function and to eliminate possible nonphysical oscillations in the slope space. An extension of this method in two-dimensions is also discussed.

Using Single-Scattering Albedo Spectral Curvature to Characterize East Asian Aerosol Mixtures

NASA Technical Reports Server (NTRS)

Li, Jing; Carlson, Barbara E.; Lacis, Andrew A.

2015-01-01

Spectral dependence of aerosol single-scattering albedo (SSA) has been used to infer aerosol composition. In particular, aerosol mixtures dominated by dust absorption will have monotonically increasing SSA with wavelength while that dominated by black carbon absorption has monotonically decreasing SSA spectra. However, by analyzing SSA measured at four wavelengths, 440, 675, 870, and 1020 nm from the Aerosol Robotic Network data set, we find that the SSA spectra over East Asia are frequently peaked at 675 nm. In these cases, we suggest that SSA spectral curvature, defined as the negative of the second derivative of SSA as a function of wavelength, can provide additional information on the composition of these aerosol mixtures. Aerosol SSA spectral curvatures for East Asia during fall and winter are considerably larger than those found in places primarily dominated by biomass burning or dust aerosols. SSA curvature is found to increase as the SSA magnitude decreases. The curvature increases with coarse mode fraction (CMF) to a CMF value of about 0.4, then slightly decreases or remains constant at larger CMF. Mie calculations further verify that the strongest SSA curvature occurs at approx. 40% dust fraction, with 10% scattering aerosol fraction. The nonmonotonic SSA spectral dependence is likely associated with enhanced absorption in the shortwave by dust, absorption by black carbon at longer wavelengths, and also the flattened absorption optical depth spectral dependence due to the increased particle size.

High Pressure Crystalline Structure and Resistance of Vanadium Dioxide to 13.5 GPa

NASA Astrophysics Data System (ADS)

Brady, Nathaniel; Appavoo, Kannatassen; Montgomery, Jeffery; Vohra, Yogesh; Haglund, Richard; Hilton, David

2013-03-01

We have investigated the insulator-to-metal transition in thin film vanadium dioxide as a function of pressure at ambient temperature using a designer diamond anvil cell (DAC). Four-point probe resistance measurements show a monotonic decrease over the entire pressure range studied with no significant discontinuity. High-pressure X-ray diffraction measurements observe an M1 (P21 / c) phase at 0 GPa, an M2 (C2/m) phase from 0.8 GPa to 1.1 GPa, and a reentrant M1 phase from 1.1 GPa to 13.5 GPa. Crystal refinement above 1.1 GPa shows a monotonically decreasing a, b and c lattice constants and a minimum in the monoclinic angle, β, near 8.5 +/-0.5 GPa. The atomic positions show that the first V-V nearest neighbor distance (d) decreases over the entire pressure range, the second nearest neighbor distance (s) increases until 5 GPa after which it is constant with s ~ f ~3.2 Å. The next most closely spaced V-V distance (f), which corresponds to V atoms in different unit cells, is approximately constant across the entire pressure range measured. NB and JM acknowledge support from the US Dept. Education GAANN Fellowship (P200A090143). KA and RH acknowledge support from the Office of Science, US Department of Energy (DE- FG02-01ER45916).

A Poisson process approximation for generalized K-5 confidence regions

NASA Technical Reports Server (NTRS)

Arsham, H.; Miller, D. R.

1982-01-01

One-sided confidence regions for continuous cumulative distribution functions are constructed using empirical cumulative distribution functions and the generalized Kolmogorov-Smirnov distance. The band width of such regions becomes narrower in the right or left tail of the distribution. To avoid tedious computation of confidence levels and critical values, an approximation based on the Poisson process is introduced. This aproximation provides a conservative confidence region; moreover, the approximation error decreases monotonically to 0 as sample size increases. Critical values necessary for implementation are given. Applications are made to the areas of risk analysis, investment modeling, reliability assessment, and analysis of fault tolerant systems.

Volatility of the catalytic hydrogenation products of 1,4 bis(phenylethynyl)benzene [The effects of hydrogenation on the volatility of organic hydrogen getters

DOE PAGES

Sharma, Hom N.; Sangalang, Elizabeth A.; Saw, Cheng K.; ...

2017-11-15

Measurements of equilibrium vapor pressures by effusion thermogravimetry and melting points by differential scanning calorimetry reveal that the melting temperature and equilibrium vapor pressures of 1,4-bis(phenylethynyl)benzene (DEB) do not vary monotonically with the hydrogenation extent. Contrary to intuition which suggests increasing volatility with hydrogenation, results indicate decreasing volatility for the first two hydrogenation steps before a non-monotonic upward trend, in which trans-isomers are less volatile. Insights on structural packing and functional groups were obtained from x-ray diffraction and infrared studies to shed light on the observed variation in the volatility of DEB with hydrogenation. Density functional theory calculations were performedmore » to obtain molecular level information and to establish the thermodynamics of DEB hydrogenation reactions. A major factor influencing the observed melting points and volatility of the hydrogenated intermediate species is identified as the local attractive or repulsive carbon-hydrogen (CH) dipole interactions among the getter molecules in their respective crystal structures. As a result, such collective CH dipole interactions can be used to predict the trends in the volatilities of catalytic hydrogenation processes.« less

Volatility of the catalytic hydrogenation products of 1,4 bis(phenylethynyl)benzene [The effects of hydrogenation on the volatility of organic hydrogen getters

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

Sharma, Hom N.; Sangalang, Elizabeth A.; Saw, Cheng K.

Measurements of equilibrium vapor pressures by effusion thermogravimetry and melting points by differential scanning calorimetry reveal that the melting temperature and equilibrium vapor pressures of 1,4-bis(phenylethynyl)benzene (DEB) do not vary monotonically with the hydrogenation extent. Contrary to intuition which suggests increasing volatility with hydrogenation, results indicate decreasing volatility for the first two hydrogenation steps before a non-monotonic upward trend, in which trans-isomers are less volatile. Insights on structural packing and functional groups were obtained from x-ray diffraction and infrared studies to shed light on the observed variation in the volatility of DEB with hydrogenation. Density functional theory calculations were performedmore » to obtain molecular level information and to establish the thermodynamics of DEB hydrogenation reactions. A major factor influencing the observed melting points and volatility of the hydrogenated intermediate species is identified as the local attractive or repulsive carbon-hydrogen (CH) dipole interactions among the getter molecules in their respective crystal structures. As a result, such collective CH dipole interactions can be used to predict the trends in the volatilities of catalytic hydrogenation processes.« less

A predator-prey model with generic birth and death rates for the predator.

PubMed

Terry, Alan J

2014-02-01

We propose and study a predator-prey model in which the predator has a Holling type II functional response and generic per capita birth and death rates. Given that prey consumption provides the energy for predator activity, and that the predator functional response represents the prey consumption rate per predator, we assume that the per capita birth and death rates for the predator are, respectively, increasing and decreasing functions of the predator functional response. These functions are monotonic, but not necessarily strictly monotonic, for all values of the argument. In particular, we allow the possibility that the predator birth rate is zero for all sufficiently small values of the predator functional response, reflecting the idea that a certain level of energy intake is needed before a predator can reproduce. Our analysis reveals that the model exhibits the behaviours typically found in predator-prey models - extinction of the predator population, convergence to a periodic orbit, or convergence to a co-existence fixed point. For a specific example, in which the predator birth and death rates are constant for all sufficiently small or large values of the predator functional response, we corroborate our analysis with numerical simulations. In the unlikely case where these birth and death rates equal the same constant for all sufficiently large values of the predator functional response, the model is capable of structurally unstable behaviour, with a small change in the initial conditions leading to a more pronounced change in the long-term dynamics. Copyright © 2013 Elsevier Inc. All rights reserved.

Convergence analysis of a monotonic penalty method for American option pricing

NASA Astrophysics Data System (ADS)

Zhang, Kai; Yang, Xiaoqi; Teo, Kok Lay

2008-12-01

This paper is devoted to study the convergence analysis of a monotonic penalty method for pricing American options. A monotonic penalty method is first proposed to solve the complementarity problem arising from the valuation of American options, which produces a nonlinear degenerated parabolic PDE with Black-Scholes operator. Based on the variational theory, the solvability and convergence properties of this penalty approach are established in a proper infinite dimensional space. Moreover, the convergence rate of the combination of two power penalty functions is obtained.

The trading time risks of stock investment in stock price drop

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Tang, Nian-Sheng; Mei, Dong-Cheng; Li, Yun-Xian; Zhang, Wan

2016-11-01

This article investigates the trading time risk (TTR) of stock investment in the case of stock price drop of Dow Jones Industrial Average (ˆDJI) and Hushen300 data (CSI300), respectively. The escape time of stock price from the maximum to minimum in a data window length (DWL) is employed to measure the absolute TTR, the ratio of the escape time to data window length is defined as the relative TTR. Empirical probability density functions of the absolute and relative TTRs for the ˆDJI and CSI300 data evidence that (i) whenever the DWL increases, the absolute TTR increases, the relative TTR decreases otherwise; (ii) there is the monotonicity (or non-monotonicity) for the stability of the absolute (or relative) TTR; (iii) there is a peak distribution for shorter trading days and a two-peak distribution for longer trading days for the PDF of ratio; (iv) the trading days play an opposite role on the absolute (or relative) TTR and its stability between ˆDJI and CSI300 data.

Water infiltration in prewetted porous media: dynamic capillary pressure and Green-Ampt modeling

NASA Astrophysics Data System (ADS)

Hsu, S.; Hilpert, M.

2013-12-01

Recently, an experimental study has shown that the modified Green-Ampt (GA) model, which accounts for a velocity-dependent capillary pressure, can describe water infiltration in dry sand columns better than the classical GA model. Studies have also shown that the initial water content of prewetted porous media affects the dynamic capillary pressure during infiltration. In this study, we performed a series of downward water infiltration experiments in prewetted sand columns for four different initial water contents: 0%, 3.3%, 6.5%, and 13.8%. We also used three different ponding heights: 10 cm, 20 cm, and 40 cm. As expected, an increase in ponding height resulted in a monotonic increase in cumulative infiltration. However, we found anomalous behavior, in that the cumulative infiltration did not monotonically decrease as the initial water content increased. When modeling the experiments with the modified GA approach, we linked this anomalous behavior to the reduction factor in the model for dynamic capillary pressure that is a function of initial water content.

Roles of inter-SWCNT junctions in resistive humidity response

NASA Astrophysics Data System (ADS)

Zhang, Kang; Zou, Jianping; Zhang, Qing

2015-11-01

As a promising chemiresistor for gas sensing, the single-walled carbon nanotube (SWCNT) network has not yet been fully utilized for humidity detection. In this work, it is found that as humidity increases from 10% to 85%, the resistance of as-grown SWCNT networks first decreases and then increases. This non-monotonic resistive response to humidity limits their sensing capabilities. The competition between SWCNT resistance and inter-tube junction resistance changes is then found to be responsible for the non-monotonic resistive humidity responses. Moreover, creating sp3 scattering centers on the SWCNT sidewall by monovalent functionalization of four-bromobenzene diazonium tetrafluoroborate is shown to be capable of eliminating the influence from the inter-tube junctions, resulting in a continuous resistance drop as humidity increases from 10% to 85%. Our results revealed the competing resistive humidity sensing process in as-grown SWCNT networks, which could also be helpful in designing and optimizing as-grown SWCNT networks for humidity sensors and other gas sensors.

Uniqueness of Nash equilibrium in vaccination games.

PubMed

Bai, Fan

2016-12-01

One crucial condition for the uniqueness of Nash equilibrium set in vaccination games is that the attack ratio monotonically decreases as the vaccine coverage level increasing. We consider several deterministic vaccination models in homogeneous mixing population and in heterogeneous mixing population. Based on the final size relations obtained from the deterministic epidemic models, we prove that the attack ratios can be expressed in terms of the vaccine coverage levels, and also prove that the attack ratios are decreasing functions of vaccine coverage levels. Some thresholds are presented, which depend on the vaccine efficacy. It is proved that for vaccination games in homogeneous mixing population, there is a unique Nash equilibrium for each game.

Binegativity of two qubits under noise

NASA Astrophysics Data System (ADS)

Sazim, Sk; Awasthi, Natasha

2018-07-01

Recently, it was argued that the binegativity might be a good quantifier of entanglement for two-qubit states. Like the concurrence and the negativity, the binegativity is also analytically computable quantifier for all two qubits. Based on numerical evidence, it was conjectured that it is a PPT (positive partial transposition) monotone and thus fulfills the criterion to be a good measure of entanglement. In this work, we investigate its behavior under noisy channels which indicate that the binegativity is decreasing monotonically with respect to increasing noise. We also find that the binegativity is closely connected to the negativity and has closed analytical form for arbitrary two qubits. Our study supports the conjecture that the binegativity is a monotone.

Monotonically increasing functions of any quantum correlation can make all multiparty states monogamous

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

Salini, K.; Prabhu, R.; Sen, Aditi

2014-09-15

Monogamy of quantum correlation measures puts restrictions on the sharability of quantum correlations in multiparty quantum states. Multiparty quantum states can satisfy or violate monogamy relations with respect to given quantum correlations. We show that all multiparty quantum states can be made monogamous with respect to all measures. More precisely, given any quantum correlation measure that is non-monogamic for a multiparty quantum state, it is always possible to find a monotonically increasing function of the measure that is monogamous for the same state. The statement holds for all quantum states, whether pure or mixed, in all finite dimensions and formore » an arbitrary number of parties. The monotonically increasing function of the quantum correlation measure satisfies all the properties that are expected for quantum correlations to follow. We illustrate the concepts by considering a thermodynamic measure of quantum correlation, called the quantum work deficit.« less

Variation in freshwater fish assemblages along a regional elevation gradient in the northern Andes, Colombia

PubMed Central

Carvajal-Quintero, Juan D; Escobar, Federico; Alvarado, Fredy; Villa-Navarro, Francisco A; Jaramillo-Villa, Úrsula; Maldonado-Ocampo, Javier A

2015-01-01

Studies on elevation diversity gradients have covered a large number of taxa and regions throughout the world; however, studies of freshwater fish are scarce and restricted to examining their changes along a specific gradient. These studies have reported a monotonic decrease in species richness with increasing elevation, but ignore the high taxonomic differentiation of each headwater assemblage that may generate high β-diversity among them. Here, we analyzed how fish assemblages vary with elevation among regional elevation bands, and how these changes are related to four environmental clines and to changes in the distribution, habitat use, and the morphology of fish species. Using a standardized field sampling technique, we assessed three different diversity and two structural assemblage measures across six regional elevation bands located in the northern Andes (Colombia). Each species was assigned to a functional group based on its body shape, habitat use, morphological, and/or behavioral adaptations. Additionally, at each sampling site, we measured four environmental variables. Our analyses showed: (1) After a monotonic decrease in species richness, we detected an increase in richness in the upper part of the gradient; (2) diversity patterns vary depending on the diversity measure used; (3) diversity patterns can be attributed to changes in species distribution and in the richness and proportions of functional groups along the regional elevation gradient; and (4) diversity patterns and changes in functional groups are highly correlated with variations in environmental variables, which also vary with elevation. These results suggest a novel pattern of variation in species richness with elevation: Species richness increases at the headwaters of the northern Andes owing to the cumulative number of endemic species there. This highlights the need for large-scale studies and has important implications for the aquatic conservation of the region. PMID:26257874

Effect of cyclic fatigue on the fracture toughness of Polyoxymethylene

NASA Astrophysics Data System (ADS)

Ramoa, B.; Berer, M.; Schwaiger, M.; Pinter, G.

2017-05-01

Polymers are used in a wide range of applications and their properties are dependent upon the morphological development during processing and the specimen configuration which in turn define the mechanical properties. In this context fatigue and monotonic testing are part of the standard procedure to assess relevant mechanical and material parameters to ensure a better part design. The present work addresses the performance issues of a real component made of Polyoxymethylene (POM) which is subjected to cyclic loads from intermediate levels to high peak values inside a damping mechanism. For this linear elastic fracture mechanics concepts were used to characterize the behavior of a POM homopolymer resin used in this application. Injection molded compact tension specimens, with sharp and blunt notches, were tested under a combination of cyclic and monotonic loads and the fracture surfaces were examined. The critical stress intensity factor obtained by monotonic tests was evaluated as a function of the cycle number, where an increase after the first 1000 cycles followed by a continuous decrease with higher numbers of cycles was observed. A variation of approximately 50% and 70% were obtained along the duration of the tests for the sharp and blunt notch specimens, respectively. In light of the obtained results, a discussion is presented considering the dynamic specimen compliance and the structural features observed on the fracture surfaces in combination with the fracture mechanical response.

Energy Criterion for the Spectral Stability of Discrete Breathers.

PubMed

Kevrekidis, Panayotis G; Cuevas-Maraver, Jesús; Pelinovsky, Dmitry E

2016-08-26

Discrete breathers are ubiquitous structures in nonlinear anharmonic models ranging from the prototypical example of the Fermi-Pasta-Ulam model to Klein-Gordon nonlinear lattices, among many others. We propose a general criterion for the emergence of instabilities of discrete breathers analogous to the well-established Vakhitov-Kolokolov criterion for solitary waves. The criterion involves the change of monotonicity of the discrete breather's energy as a function of the breather frequency. Our analysis suggests and numerical results corroborate that breathers with increasing (decreasing) energy-frequency dependence are generically unstable in soft (hard) nonlinear potentials.

Root mean square fluctuation of a weak magnetic field in an infinite medium of homogeneous stationary turbulence.

NASA Technical Reports Server (NTRS)

Low, B.-C.

1972-01-01

The generation of a magnetic field by statistically homogeneous, stationary velocity turbulence is considered. The generation of rms magnetic fluctuation is explicitly demonstrated in the limit of short turbulence correlation time. It is shown that the fluctuation associated with a growing or stationary mean field grows with time such that the ratio of the fluctuation and the square of the mean field tends to a steady value, which is a monotonically decreasing function of the growth rate of the mean field.

Entanglement of heavy quark impurities and generalized gravitational entropy

NASA Astrophysics Data System (ADS)

Kumar, S. Prem; Silvani, Dorian

2018-01-01

We calculate the contribution from non-conformal heavy quark sources to the entanglement entropy (EE) of a spherical region in N=4 SUSY Yang-Mills theory. We apply the generalized gravitational entropy method to non-conformal probe D-brane embeddings in AdS5×S5, dual to pointlike impurities exhibiting flows between quarks in large-rank tensor representations and the fundamental representation. For the D5-brane embedding which describes the screening of fundamental quarks in the UV to the antisymmetric tensor representation in the IR, the EE excess decreases non-monotonically towards its IR asymptotic value, tracking the qualitative behaviour of the one-point function of static fields sourced by the impurity. We also examine two classes of D3-brane embeddings, one which connects a symmetric representation source in the UV to fundamental quarks in the IR, and a second category which yields the symmetric representation source on the Coulomb branch. The EE excess for the former increases from the UV to the IR, whilst decreasing and becoming negative for the latter. In all cases, the probe free energy on hyperbolic space with β = 2 π increases monotonically towards the IR, supporting its interpretation as a relative entropy. We identify universal corrections, depending logarithmically on the VEV, for the symmetric representation on the Coulomb branch.

Diffusive dynamics of nanoparticles in ultra-confined media

DOE PAGES

Jacob, Jack Deodato; Conrad, Jacinta; Krishnamoorti, Ramanan; ...

2015-08-10

Differential dynamic microscopy (DDM) was used to investigate the diffusive dynamics of nanoparticles of diameter 200 400 nm that were strongly confined in a periodic square array of cylindrical nanoposts. The minimum distance between posts was 1.3 5 times the diameter of the nanoparticles. The image structure functions obtained from the DDM analysis were isotropic and could be fit by a stretched exponential function. The relaxation time scaled diffusively across the range of wave vectors studied, and the corresponding scalar diffusivities decreased monotonically with increased confinement. The decrease in diffusivity could be described by models for hindered diffusion that accountedmore » for steric restrictions and hydrodynamic interactions. The stretching exponent decreased linearly as the nanoparticles were increasingly confined by the posts. Altogether, these results are consistent with a picture in which strongly confined nanoparticles experience a heterogeneous spatial environment arising from hydrodynamics and volume exclusion on time scales comparable to cage escape, leading to multiple relaxation processes and Fickian but non-Gaussian diffusive dynamics.« less

Monostable traveling waves for a time-periodic and delayed nonlocal reaction-diffusion equation

NASA Astrophysics Data System (ADS)

Li, Panxiao; Wu, Shi-Liang

2018-04-01

This paper is concerned with a time-periodic and delayed nonlocal reaction-diffusion population model with monostable nonlinearity. Under quasi-monotone or non-quasi-monotone assumptions, it is known that there exists a critical wave speed c_*>0 such that a periodic traveling wave exists if and only if the wave speed is above c_*. In this paper, we first prove the uniqueness of non-critical periodic traveling waves regardless of whether the model is quasi-monotone or not. Further, in the quasi-monotone case, we establish the exponential stability of non-critical periodic traveling fronts. Finally, we illustrate the main results by discussing two types of death and birth functions arising from population biology.

Matrix cracking in laminated composites under monotonic and cyclic loadings

NASA Technical Reports Server (NTRS)

Allen, David H.; Lee, Jong-Won

1991-01-01

An analytical model based on the internal state variable (ISV) concept and the strain energy method is proposed for characterizing the monotonic and cyclic response of laminated composites containing matrix cracks. A modified constitution is formulated for angle-ply laminates under general in-plane mechanical loading and constant temperature change. A monotonic matrix cracking criterion is developed for predicting the crack density in cross-ply laminates as a function of the applied laminate axial stress. An initial formulation for a cyclic matrix cracking criterion for cross-ply laminates is also discussed. For the monotonic loading case, a number of experimental data and well-known models are compared with the present study for validating the practical applicability of the ISV approach.

Non-monotonic changes in clonogenic cell survival induced by disulphonated aluminum phthalocyanine photodynamic treatment in a human glioma cell line

PubMed Central

2010-01-01

Background Photodynamic therapy (PDT) involves excitation of sensitizer molecules by visible light in the presence of molecular oxygen, thereby generating reactive oxygen species (ROS) through electron/energy transfer processes. The ROS, thus produced can cause damage to both the structure and the function of the cellular constituents resulting in cell death. Our preliminary investigations of dose-response relationships in a human glioma cell line (BMG-1) showed that disulphonated aluminum phthalocyanine (AlPcS2) photodynamically induced loss of cell survival in a concentration dependent manner up to 1 μM, further increases in AlPcS2concentration (>1 μM) were, however, observed to decrease the photodynamic toxicity. Considering the fact that for most photosensitizers only monotonic dose-response (survival) relationships have been reported, this result was unexpected. The present studies were, therefore, undertaken to further investigate the concentration dependent photodynamic effects of AlPcS2. Methods Concentration-dependent cellular uptake, sub-cellular localization, proliferation and photodynamic effects of AlPcS2 were investigated in BMG-1 cells by absorbance and fluorescence measurements, image analysis, cell counting and colony forming assays, flow cytometry and micronuclei formation respectively. Results The cellular uptake as a function of extra-cellular AlPcS2 concentrations was observed to be biphasic. AlPcS2 was distributed throughout the cytoplasm with intense fluorescence in the perinuclear regions at a concentration of 1 μM, while a weak diffuse fluorescence was observed at higher concentrations. A concentration-dependent decrease in cell proliferation with accumulation of cells in G2+M phase was observed after PDT. The response of clonogenic survival after AlPcS2-PDT was non-monotonic with respect to AlPcS2 concentration. Conclusions Based on the results we conclude that concentration-dependent changes in physico-chemical properties of sensitizer such as aggregation may influence intracellular transport and localization of photosensitizer. Consequent modifications in the photodynamic induction of lesions and their repair leading to different modes of cell death may contribute to the observed non-linear effects. PMID:20433757

Regional trends in short-duration precipitation extremes: a flexible multivariate monotone quantile regression approach

NASA Astrophysics Data System (ADS)

Cannon, Alex

2017-04-01

Estimating historical trends in short-duration rainfall extremes at regional and local scales is challenging due to low signal-to-noise ratios and the limited availability of homogenized observational data. In addition to being of scientific interest, trends in rainfall extremes are of practical importance, as their presence calls into question the stationarity assumptions that underpin traditional engineering and infrastructure design practice. Even with these fundamental challenges, increasingly complex questions are being asked about time series of extremes. For instance, users may not only want to know whether or not rainfall extremes have changed over time, they may also want information on the modulation of trends by large-scale climate modes or on the nonstationarity of trends (e.g., identifying hiatus periods or periods of accelerating positive trends). Efforts have thus been devoted to the development and application of more robust and powerful statistical estimators for regional and local scale trends. While a standard nonparametric method like the regional Mann-Kendall test, which tests for the presence of monotonic trends (i.e., strictly non-decreasing or non-increasing changes), makes fewer assumptions than parametric methods and pools information from stations within a region, it is not designed to visualize detected trends, include information from covariates, or answer questions about the rate of change in trends. As a remedy, monotone quantile regression (MQR) has been developed as a nonparametric alternative that can be used to estimate a common monotonic trend in extremes at multiple stations. Quantile regression makes efficient use of data by directly estimating conditional quantiles based on information from all rainfall data in a region, i.e., without having to precompute the sample quantiles. The MQR method is also flexible and can be used to visualize and analyze the nonlinearity of the detected trend. However, it is fundamentally a univariate technique, and cannot incorporate information from additional covariates, for example ENSO state or physiographic controls on extreme rainfall within a region. Here, the univariate MQR model is extended to allow the use of multiple covariates. Multivariate monotone quantile regression (MMQR) is based on a single hidden-layer feedforward network with the quantile regression error function and partial monotonicity constraints. The MMQR model is demonstrated via Monte Carlo simulations and the estimation and visualization of regional trends in moderate rainfall extremes based on homogenized sub-daily precipitation data at stations in Canada.

Laser induced non-monotonic degradation in short-circuit current of triple-junction solar cells

NASA Astrophysics Data System (ADS)

Dou, Peng-Cheng; Feng, Guo-Bin; Zhang, Jian-Min; Song, Ming-Ying; Zhang, Zhen; Li, Yun-Peng; Shi, Yu-Bin

2018-06-01

In order to study the continuous wave (CW) laser radiation effects and mechanism of GaInP/GaAs/Ge triple-junction solar cells (TJSCs), 1-on-1 mode irradiation experiments were carried out. It was found that the post-irradiation short circuit current (ISC) of the TJSCs initially decreased and then increased with increasing of irradiation laser power intensity. To explain this phenomenon, a theoretical model had been established and then verified by post-damage tests and equivalent circuit simulations. Conclusion was drawn that laser induced alterations in the surface reflection and shunt resistance were the main causes for the observed non-monotonic decrease in the ISC of the TJSCs.

Neurons sensitive to narrow ranges of repetitive acoustic transients in the medial geniculate body of the cat.

PubMed

Rouiller, E; de Ribaupierre, F

1982-01-01

Neuronal activity was recorded in the medial geniculate body (MGB) of nitrous oxide anaesthetized, paralysed cats in response to click trains. For most cells responding to these stimuli the spike discharges are precisely time locked to individual clicks within the train. The present study has revealed that, apart from the normal "locker" response being characterized by a monotonic decrease in the entrainment as the frequency of the clicks within the train increases, there is a small population of "lockers" which show a non-monotonic response to increasing click frequency. 41% of these non-monotonic cells were not at all entrained by the lowest click rates and had time-locked responses for very restricted frequency ranges. These particular non-monotonic "lockers" were more commonly-found in the posterior part of the pars lateralis and in the suprageniculate nucleus. These cells might be involved in the temporal coding of natural sounds such as animal vocalizations and the cat's purr.

A method for deriving lower bounds for the complexity of monotone arithmetic circuits computing real polynomials

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

Gashkov, Sergey B; Sergeev, Igor' S

2012-10-31

This work suggests a method for deriving lower bounds for the complexity of polynomials with positive real coefficients implemented by circuits of functional elements over the monotone arithmetic basis {l_brace}x+y, x {center_dot} y{r_brace} Union {l_brace}a {center_dot} x | a Element-Of R{sub +}{r_brace}. Using this method, several new results are obtained. In particular, we construct examples of polynomials of degree m-1 in each of the n variables with coefficients 0 and 1 having additive monotone complexity m{sup (1-o(1))n} and multiplicative monotone complexity m{sup (1/2-o(1))n} as m{sup n}{yields}{infinity}. In this form, the lower bounds derived here are sharp. Bibliography: 72 titles.

Nonlinear relationship between the Product Consistency Test (PCT) response and the Al/B ratio in a soda-lime aluminoborosilicate glass

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

Farooqi, Rahmat Ullah; Hrma, Pavel

2016-06-01

We have investigated the effect of A1/B ratio on the Product Consistency Test (PCT) response. In an aluminoborosilicate soda-lime glass based on a modified International Simple Glass, ISG-3, the A1/B ratio varied from 0 to 0.55 (in mole fractions). In agreement with various models of the PCT response as a function of glass composition, we observed a monotonic increase of B and Na releases with decreasing A1/B mole ratio, but only when the ratio was higher than 0.05. Below this value (A1/B < 0.05), we observed a sharp decrease that we attribute to B in tetrahedral coordination.

Theoretical study of the NO gamma system

NASA Technical Reports Server (NTRS)

Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Partridge, Harry

1988-01-01

A systematic study of the NO gamma system with level of correlation treatment was carried out using large Gaussian basis sets to determine the potential curves for the X2Pi and A2Sigma(+) states of NO. It is shown that the A2Sigma-X2Pi electronic transition moment (gamma system) increases monotonically with decreasing internuclear distance and that the increase in the moment as r decreases is correlated with the increasing degree of diffuse character in the X2Pi state. The results of a study of the X2Pi and A2Sigma(+) dipole moment functions showed that the X2Pi vibrationally averaged dipole moments and the (1-0) and (2-0) vibration-rotation band intensities agree well with experimental data.

Random search optimization based on genetic algorithm and discriminant function

NASA Technical Reports Server (NTRS)

Kiciman, M. O.; Akgul, M.; Erarslanoglu, G.

1990-01-01

The general problem of optimization with arbitrary merit and constraint functions, which could be convex, concave, monotonic, or non-monotonic, is treated using stochastic methods. To improve the efficiency of the random search methods, a genetic algorithm for the search phase and a discriminant function for the constraint-control phase were utilized. The validity of the technique is demonstrated by comparing the results to published test problem results. Numerical experimentation indicated that for cases where a quick near optimum solution is desired, a general, user-friendly optimization code can be developed without serious penalties in both total computer time and accuracy.

Secondary ion generation mechanism studied by ISS-SIMS and work function measurements

NASA Astrophysics Data System (ADS)

Kawatoh, Eizoh; Terada, Norihito; Shimizu, Ryuichi; Kang, Hee Jae

1989-03-01

Oxygen enhancement effects in secondary ion generation were studied in polycrystalline Ni at different partial pressures of oxygen, Po2, by sequential ISS-SIMS and work function measurements. The investigation has revealed that the enhancement undergoes three stages: (I) The secondary ion intensity increases monotonically with an increase of work function which is described very well by the electron tunneling model. (II) This tendency abruptly changes, i.e. the work function decreases and the secondary ion intensity increases rapidly, for a slight increase of Po2 (III) The secondary ion intensities gradually increase and become saturated with a further increase of Po2. It has also been found that the critical coverage, θc, corresponds exactly to the stage (II) behaviour, which was observed by Blaise and Bernheim for a single crystal (100)Ni surface.

Multistability of neural networks with discontinuous non-monotonic piecewise linear activation functions and time-varying delays.

PubMed

Nie, Xiaobing; Zheng, Wei Xing

2015-05-01

This paper is concerned with the problem of coexistence and dynamical behaviors of multiple equilibrium points for neural networks with discontinuous non-monotonic piecewise linear activation functions and time-varying delays. The fixed point theorem and other analytical tools are used to develop certain sufficient conditions that ensure that the n-dimensional discontinuous neural networks with time-varying delays can have at least 5(n) equilibrium points, 3(n) of which are locally stable and the others are unstable. The importance of the derived results is that it reveals that the discontinuous neural networks can have greater storage capacity than the continuous ones. Moreover, different from the existing results on multistability of neural networks with discontinuous activation functions, the 3(n) locally stable equilibrium points obtained in this paper are located in not only saturated regions, but also unsaturated regions, due to the non-monotonic structure of discontinuous activation functions. A numerical simulation study is conducted to illustrate and support the derived theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Studies of the oxidized Cu(100) surface using positron annihilation induced Auger electron spectroscopy

NASA Astrophysics Data System (ADS)

Maddox, W.; Fazleev, N. G.; Nadesalingam, M. P.; Weiss, A. H.

2008-03-01

We discuss recent progress in studies of an oxidized Cu(100) single crystal subjected to vacuum annealing over a temperature range from 293K to 1073K using positron annihilation induced Auger electron spectroscopy (PAES). The PAES measurements show a large monotonic increase in the intensity of the positron annihilation induced Cu M2,3 VV Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 573 K. The intensity then decreases monotonically as the annealing temperature is increased to 873 K. Experimental PAES results are analyzed by performing calculations of positron surface states and annihilation probabilities of surface-trapped positrons with relevant core electrons taking into account the charge redistribution at the surface, surface reconstructions, and electron-positron correlations effects. The effects of oxygen adsorption and surface reconstruction on localization of positron surface state wave functions and annihilation characteristics are analyzed. Possible explanations are provided for the observed behavior of the intensity of positron annihilation induced Cu M2,3VV Auger peak with changes of the annealing temperature.

Parallel Monotonic Basin Hopping for Low Thrust Trajectory Optimization

NASA Technical Reports Server (NTRS)

McCarty, Steven L.; McGuire, Melissa L.

2018-01-01

Monotonic Basin Hopping has been shown to be an effective method of solving low thrust trajectory optimization problems. This paper outlines an extension to the common serial implementation by parallelizing it over any number of available compute cores. The Parallel Monotonic Basin Hopping algorithm described herein is shown to be an effective way to more quickly locate feasible solutions, and improve locally optimal solutions in an automated way without requiring a feasible initial guess. The increased speed achieved through parallelization enables the algorithm to be applied to more complex problems that would otherwise be impractical for a serial implementation. Low thrust cislunar transfers and a hybrid Mars example case demonstrate the effectiveness of the algorithm. Finally, a preliminary scaling study quantifies the expected decrease in solve time compared to a serial implementation.,

Information flow in layered networks of non-monotonic units

NASA Astrophysics Data System (ADS)

Schittler Neves, Fabio; Martim Schubert, Benno; Erichsen, Rubem, Jr.

2015-07-01

Layered neural networks are feedforward structures that yield robust parallel and distributed pattern recognition. Even though much attention has been paid to pattern retrieval properties in such systems, many aspects of their dynamics are not yet well characterized or understood. In this work we study, at different temperatures, the memory activity and information flows through layered networks in which the elements are the simplest binary odd non-monotonic function. Our results show that, considering a standard Hebbian learning approach, the network information content has its maximum always at the monotonic limit, even though the maximum memory capacity can be found at non-monotonic values for small enough temperatures. Furthermore, we show that such systems exhibit rich macroscopic dynamics, including not only fixed point solutions of its iterative map, but also cyclic and chaotic attractors that also carry information.

Diffuse prior monotonic likelihood ratio test for evaluation of fused image quality measures.

PubMed

Wei, Chuanming; Kaplan, Lance M; Burks, Stephen D; Blum, Rick S

2011-02-01

This paper introduces a novel method to score how well proposed fused image quality measures (FIQMs) indicate the effectiveness of humans to detect targets in fused imagery. The human detection performance is measured via human perception experiments. A good FIQM should relate to perception results in a monotonic fashion. The method computes a new diffuse prior monotonic likelihood ratio (DPMLR) to facilitate the comparison of the H(1) hypothesis that the intrinsic human detection performance is related to the FIQM via a monotonic function against the null hypothesis that the detection and image quality relationship is random. The paper discusses many interesting properties of the DPMLR and demonstrates the effectiveness of the DPMLR test via Monte Carlo simulations. Finally, the DPMLR is used to score FIQMs with test cases considering over 35 scenes and various image fusion algorithms.

Dynamical Friction in Multi-component Evolving Globular Clusters

NASA Astrophysics Data System (ADS)

Alessandrini, Emiliano; Lanzoni, Barbara; Miocchi, Paolo; Ciotti, Luca; Ferraro, Francesco R.

2014-11-01

We use the Chandrasekhar formalism and direct N-body simulations to study the effect of dynamical friction on a test object only slightly more massive than the field stars, orbiting a spherically symmetric background of particles with a mass spectrum. The main goal is to verify whether the dynamical friction time (t DF) develops a non-monotonic radial dependence that could explain the bimodality of the blue straggler radial distributions observed in globular clusters. In these systems, in fact, relaxation effects lead to a mass and velocity radial segregation of the different mass components, so that mass-spectrum effects on t DF are expected to be dependent on radius. We find that in spite of the presence of different masses, t DF is always a monotonic function of radius, at all evolutionary times and independently of the initial concentration of the simulated cluster. This is because the radial dependence of t DF is largely dominated by the total mass density profile of the background stars (which is monotonically decreasing with radius). Hence, a progressive temporal erosion of the blue straggler star (BSS) population at larger and larger distances from the cluster center remains the simplest and the most likely explanation of the shape of the observed BSS radial distributions, as suggested in previous works. We also confirm the theoretical expectation that approximating a multi-mass globular cluster as made of (averaged) equal-mass stars can lead to significant overestimations of t DF within the half-mass radius.

Sakiadis flow of Maxwell fluid considering magnetic field and convective boundary conditions

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

Mustafa, M., E-mail: meraj-mm@hotmail.com; Khan, Junaid Ahmad; Hayat, T.

2015-02-15

In this paper we address the flow of Maxwell fluid due to constantly moving flat radiative surface with convective condition. The flow is under the influence of non-uniform transverse magnetic field. The velocity and temperature distributions have been evaluated numerically by shooting approach. The solution depends on various interesting parameters including local Deborah number De, magnetic field parameter M, Prandtl number Pr and Biot number Bi. We found that variation in velocity with an increase in local Deborah number De is non-monotonic. However temperature is a decreasing function of local Deborah number De.

Minority game with local interactions due to the presence of herding behavior

NASA Astrophysics Data System (ADS)

Cajueiro, Daniel Oliveira; de Camargo, Reinaldo Soares

2006-07-01

In this Letter we introduce a framework to study local interactions due to the presence of herding behavior in a minority game. The idea behind this approach is to consider that some of the agents who play the game imitate some of their neighbors who are believed to be more informed than themselves. We show that under herding behavior the cooperation between the agents is less efficient than the one which arises in the standard minority game and that the curve volatility of the attendance size as a function of the memory may be a monotone decreasing curve.

Examining a scaled dynamical system of telomere shortening

NASA Astrophysics Data System (ADS)

Cyrenne, Benoit M.; Gooding, Robert J.

2015-02-01

A model of telomere dynamics is proposed and examined. Our model, which extends a previously introduced model that incorporates stem cells as progenitors of new cells, imposes the Hayflick limit, the maximum number of cell divisions that are possible. This new model leads to cell populations for which the average telomere length is not necessarily a monotonically decreasing function of time, in contrast to previously published models. We provide a phase diagram indicating where such results would be expected via the introduction of scaled populations, rate constants and time. The application of this model to available leukocyte baboon data is discussed.

Discovering monotonic stemness marker genes from time-series stem cell microarray data.

PubMed

Wang, Hsei-Wei; Sun, Hsing-Jen; Chang, Ting-Yu; Lo, Hung-Hao; Cheng, Wei-Chung; Tseng, George C; Lin, Chin-Teng; Chang, Shing-Jyh; Pal, Nikhil; Chung, I-Fang

2015-01-01

Identification of genes with ascending or descending monotonic expression patterns over time or stages of stem cells is an important issue in time-series microarray data analysis. We propose a method named Monotonic Feature Selector (MFSelector) based on a concept of total discriminating error (DEtotal) to identify monotonic genes. MFSelector considers various time stages in stage order (i.e., Stage One vs. other stages, Stages One and Two vs. remaining stages and so on) and computes DEtotal of each gene. MFSelector can successfully identify genes with monotonic characteristics. We have demonstrated the effectiveness of MFSelector on two synthetic data sets and two stem cell differentiation data sets: embryonic stem cell neurogenesis (ESCN) and embryonic stem cell vasculogenesis (ESCV) data sets. We have also performed extensive quantitative comparisons of the three monotonic gene selection approaches. Some of the monotonic marker genes such as OCT4, NANOG, BLBP, discovered from the ESCN dataset exhibit consistent behavior with that reported in other studies. The role of monotonic genes found by MFSelector in either stemness or differentiation is validated using information obtained from Gene Ontology analysis and other literature. We justify and demonstrate that descending genes are involved in the proliferation or self-renewal activity of stem cells, while ascending genes are involved in differentiation of stem cells into variant cell lineages. We have developed a novel system, easy to use even with no pre-existing knowledge, to identify gene sets with monotonic expression patterns in multi-stage as well as in time-series genomics matrices. The case studies on ESCN and ESCV have helped to get a better understanding of stemness and differentiation. The novel monotonic marker genes discovered from a data set are found to exhibit consistent behavior in another independent data set, demonstrating the utility of the proposed method. The MFSelector R function and data sets can be downloaded from: http://microarray.ym.edu.tw/tools/MFSelector/.

Formation of multiferroic PbTiO3/PbFe12O19 composite by exceeding the solubility limit of Fe in PbTiO3

NASA Astrophysics Data System (ADS)

Jaffari, G. Hassnain; Bilal, M.; Ur Rahman, Jamil; Lee, Soonil

2017-09-01

PbTiO3/PbFe12O19 composites have been synthesized by keeping the Fe concentration (x) in PbFexTi1-xO3 beyond solubility limit, i.e., x > 0.1% and 5% Pb excess. Both these factors have been successfully utilized to extract Fe doped PbTiO3 tetragonal phase which is composited with Magnetoplumbite (PbFe12O19) phase. A systematic evolution of the tetragonality of the former and improved stoichiometry of the later constituent has been observed. As x increases, emergence of additional Raman mode around 650 cm-1 with Fe addition was observed. Systematic increase in the relative intensity of this mode with x, showed that this mode corresponds to the magnetoplumbite phase. In addition to that resultant composite exhibited noticeable systematic decrease in the value of the energy gap as a function of x. Increasing Fe concentration in PbTiO3 constituent, led to monotonic decrease in c/a and increase in strain experienced by PbTiO3. Increase in the value of the saturation polarization was observed up to x = 0.4, which is identified to be associated with the strain induced by the dopant. A comprehensive magnetic characterization revealed monotonic decrease in magnetization with temperature for all compositions. Finally, we found an anomalous temperature dependent trend in the magnetic coercivity which is explained in terms of low temperature decrease in effective magnetic anisotropy by including magneto-electric coupling. Both constituent phases in the composite being ferroelectric and ferromagnetic at room temperature led to formation of better multiferroic properties and exhibited tunable physical properties with x.

Pressure-induced superconductivity in parent CaFeAsF single crystals

NASA Astrophysics Data System (ADS)

Gao, Bo; Ma, Yonghui; Mu, Gang; Xiao, Hong

2018-05-01

Flouroarsenide CaFeAsF is a parent compound of the 1111 type of iron-based superconductors. It is similar to the parent LaFeAsO, but it is oxygen-free. To date, studies of pressure-induced effects have only focused on pure and doped polycrystalline CaFeAsF samples. Here, we carried out high-pressure electrical resistivity and Hall coefficient measurements up to 48.2 GPa on single crystals of CaFeAsF. The structural transition temperature Tstr decreased monotonically upon increasing the pressure, and reached ˜60 K at 9.6 GPa. Superconductivity emerged suddenly at 8.6 GPa with the Tc ,onset˜25.7 K , which decreased monotonically with increasing pressure to 5.7 K under 48.2 GPa. Moreover, just after the appearance of superconductivity, the Hall coefficient at 40 K started to decrease with increasing pressure, while keeping its sign negative persisting up to 48.2 GPa.

Effects of inhomogeneous activity of players and noise on cooperation in spatial public goods games

NASA Astrophysics Data System (ADS)

Guan, Jian-Yue; Wu, Zhi-Xi; Wang, Ying-Hai

2007-11-01

We study the public goods game in the noisy case by considering the players with inhomogeneous activity of teaching on a square lattice. It is shown that the introduction of the inhomogeneous activity of teaching the players can remarkably promote cooperation. By investigating the effects of noise on cooperative behavior in detail, we find that the variation of cooperator density ρC with the noise parameter κ displays several different behaviors: ρC monotonically increases (decreases) with κ ; ρC first increases (decreases) with κ and then it decreases (increases) monotonically after reaching its maximum (minimum) value, which depends on the amount of the multiplication factor r , on whether the system is homogeneous or inhomogeneous, and on whether the adopted updating is synchronous or asynchronous. These results imply that the noise plays an important and nontrivial role in the evolution of cooperation.

NITRIC OXIDE FORMATION DURING PULVERIZED COAL COMBUSTION

EPA Science Inventory

Data on the overall conversion of coal-nitrogen to NOx were obtained at 1250 K and 1750 K for a residence time of one second. The conversion of coal-nitrogen to NOx decreased monotonically with increasing fuel/oxygen equivalence ratio and decreased slightly with increasing temper...

Searching for an Axis-Parallel Shoreline

NASA Astrophysics Data System (ADS)

Langetepe, Elmar

We are searching for an unknown horizontal or vertical line in the plane under the competitive framework. We design a framework for lower bounds on all cyclic and monotone strategies that result in two-sequence functionals. For optimizing such functionals we apply a method that combines two main paradigms. The given solution shows that the combination method is of general interest. Finally, we obtain the current best strategy and can prove that this is the best strategy among all cyclic and monotone strategies which is a main step toward a lower bound construction.

Aerosol Microphysical and Radiative Effects on Continental Cloud Ensembles

DOE PAGES

Wang, Yuan; Vogel, Jonathan M.; Lin, Yun; ...

2018-01-10

Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. Here, an aerosol-aware Weather Research and Forecasting (WRF) model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the Southern Great Plains site of the US Atmospheric Radiation Measurement Program. Three cloud ensembles with different meteorological conditions are simulated, including a low-pressure deep convective cloud system, a series ofmore » lessprecipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by the available observations of cloud fraction, liquid water path, precipitation, and surface temperature. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not interfere the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with more prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. Furthermore, the simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the direction of precipitation changes by the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity (typically less than 2%) to aerosol perturbations than the cloud microphysics, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type. Surface temperature changes closely follow the modulation of the surface radiation fluxes.« less

Aerosol Microphysical and Radiative Effects on Continental Cloud Ensembles

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

Wang, Yuan; Vogel, Jonathan M.; Lin, Yun

Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. Here, an aerosol-aware Weather Research and Forecasting (WRF) model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the Southern Great Plains site of the US Atmospheric Radiation Measurement Program. Three cloud ensembles with different meteorological conditions are simulated, including a low-pressure deep convective cloud system, a series ofmore » lessprecipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by the available observations of cloud fraction, liquid water path, precipitation, and surface temperature. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not interfere the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with more prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. Furthermore, the simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the direction of precipitation changes by the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity (typically less than 2%) to aerosol perturbations than the cloud microphysics, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type. Surface temperature changes closely follow the modulation of the surface radiation fluxes.« less

Narrow sound pressure level tuning in the auditory cortex of the bats Molossus molossus and Macrotus waterhousii.

PubMed

Macías, Silvio; Hechavarría, Julio C; Cobo, Ariadna; Mora, Emanuel C

2014-03-01

In the auditory system, tuning to sound level appears in the form of non-monotonic response-level functions that depict the response of a neuron to changing sound levels. Neurons with non-monotonic response-level functions respond best to a particular sound pressure level (defined as "best level" or level evoking the maximum response). We performed a comparative study on the location and basic functional organization of the auditory cortex in the gleaning bat, Macrotus waterhousii, and the aerial-hawking bat, Molossus molossus. Here, we describe the response-level function of cortical units in these two species. In the auditory cortices of M. waterhousii and M. molossus, the characteristic frequency of the units increased from caudal to rostral. In M. waterhousii, there was an even distribution of characteristic frequencies while in M. molossus there was an overrepresentation of frequencies present within echolocation pulses. In both species, most of the units showed best levels in a narrow range, without an evident topography in the amplitopic organization, as described in other species. During flight, bats decrease the intensity of their emitted pulses when they approach a prey item or an obstacle resulting in maintenance of perceived echo intensity. Narrow level tuning likely contributes to the extraction of echo amplitudes facilitating echo-intensity compensation. For aerial-hawking bats, like M. molossus, receiving echoes within the optimal sensitivity range can help the bats to sustain consistent analysis of successive echoes without distortions of perception caused by changes in amplitude. Copyright © 2013 Elsevier B.V. All rights reserved.

Efficient estimation of the attributable fraction when there are monotonicity constraints and interactions.

PubMed

Traskin, Mikhail; Wang, Wei; Ten Have, Thomas R; Small, Dylan S

2013-01-01

The PAF for an exposure is the fraction of disease cases in a population that can be attributed to that exposure. One method of estimating the PAF involves estimating the probability of having the disease given the exposure and confounding variables. In many settings, the exposure will interact with the confounders and the confounders will interact with each other. Also, in many settings, the probability of having the disease is thought, based on subject matter knowledge, to be a monotone increasing function of the exposure and possibly of some of the confounders. We develop an efficient approach for estimating logistic regression models with interactions and monotonicity constraints, and apply this approach to estimating the population attributable fraction (PAF). Our approach produces substantially more accurate estimates of the PAF in some settings than the usual approach which uses logistic regression without monotonicity constraints.

Note on a Family of Monotone Quantum Relative Entropies

NASA Astrophysics Data System (ADS)

Deuchert, Andreas; Hainzl, Christian; Seiringer, Robert

2015-10-01

Given a convex function and two hermitian matrices A and B, Lewin and Sabin study in (Lett Math Phys 104:691-705, 2014) the relative entropy defined by . Among other things, they prove that the so-defined quantity is monotone if and only if is operator monotone. The monotonicity is then used to properly define for bounded self-adjoint operators acting on an infinite-dimensional Hilbert space by a limiting procedure. More precisely, for an increasing sequence of finite-dimensional projections with strongly, the limit is shown to exist and to be independent of the sequence of projections . The question whether this sequence converges to its "obvious" limit, namely , has been left open. We answer this question in principle affirmatively and show that . If the operators A and B are regular enough, that is ( A - B), and are trace-class, the identity holds.

Feasibility study of oxygen-dispensing emitters for thermionic converters, phase 1

NASA Technical Reports Server (NTRS)

Desteese, J. G.

1972-01-01

A metal/ceramic Marchuk tube was used to measure work functions of oxygen-doped tantalum, to determine applicability of the material to plasma-mode thermionic converters. Oxygen-doped tantalum was shown to increase in work function monotonically with oxygen doping in the range 0.1 to 0.3 atomic percent. Oxygenated test emitters were run at an average temperature of 2165 K and a T/T sub Cs ratio -5.8 to observe the influence of oxygen depletion. Bare work function decreased with outgassing of oxygen. Projections were made based on outgassing kinetics and area/volume ratios to calculate the longevity of oxygen doping in a practical converter. Calculations indicated that the program goal of 10,000 hr could be achieved at 1800 K with an initial oxygen doping of 1 atomic percent and a practical emitter area/volume ratio.

Directed translocation of a flexible polymer through a cone-shaped nano-channel

NASA Astrophysics Data System (ADS)

Nikoofard, Narges; Khalilian, Hamidreza; Fazli, Hossein

2013-08-01

Translocation of a flexible polymer through a cone-shaped channel is studied, theoretically and using computer simulations. Our simulations show that the shape of the channel causes the polymer translocation to be a driven process. The effective driving force of entropic origin acting on the polymer is calculated as a function of the length and the apex-angle of the channel, theoretically. It is found that the translocation time is a non-monotonic function of the apex-angle of the channel. By increasing the apex-angle from zero, the translocation time shows a minimum and then a maximum. Also, it is found that regardless of the value of the apex-angle, the translocation time is a uniformly decreasing function of the channel length. The results of the theory and the simulation are in good qualitative agreement.

Internal Waves in CVX

NASA Technical Reports Server (NTRS)

Berg, Robert F.

1996-01-01

Near the liquid-vapor critical point, density stratification supports internal gravity waves which affect 1-g viscosity measurements in the CVX (Critical Viscosity of Xenon) experiment. Two internal-wave modes were seen in the horizontal viscometer. The frequencies of the two modes had different temperature dependences: with decreasing temperature, the higher frequency increased monotonically from 0.7 to 2.8 Hz, but the lower frequency varied non-monotonically, with a maximum of 1.0 Hz at 20 mK above the critical temperature. The measured frequencies agree with independently calculated frequencies to within 15%.

Amorphization and recrystallization of epitaxial ReSi2 films grown on Si(100)

NASA Technical Reports Server (NTRS)

Kim, Kun HO; Bai, G.; Nicolet, MARC-A.; Mahan, John E.; Geib, Kent M.

1991-01-01

The effects of implantation damage and the chemical species of the implant on structural and electrical properties of epitaxial ReSi2 films on Si(100) implanted with Si-28 or Ar-40 ions, at doses ranging from 10 to the 13th/sq cm to 10 to the 15th/sq cm, were investigated using the backscattering spectrometry, XRD, and the van der Pauw techniques. Results showed that ion implantation produces damage in the film, which increases monotonically with dose; the resistivity of the film decreases monotonically with dose.

Mechanical annealing under low-amplitude cyclic loading in micropillars

NASA Astrophysics Data System (ADS)

Cui, Yi-nan; Liu, Zhan-li; Wang, Zhang-jie; Zhuang, Zhuo

2016-04-01

Mechanical annealing has been demonstrated to be an effective method for decreasing the overall dislocation density in submicron single crystal. However, simultaneously significant shape change always unexpectedly happens under extremely high monotonic loading to drive the pre-existing dislocations out of the free surfaces. In the present work, through in situ TEM experiments it is found that cyclic loading with low stress amplitude can drive most dislocations out of the submicron sample with virtually little change of the shape. The underlying dislocation mechanism is revealed by carrying out discrete dislocation dynamic (DDD) simulations. The simulation results indicate that the dislocation density decreases within cycles, while the accumulated plastic strain is small. By comparing the evolution of dislocation junction under monotonic, cyclic and relaxation deformation, the cumulative irreversible slip is found to be the key factor of promoting junction destruction and dislocation annihilation at free surface under low-amplitude cyclic loading condition. By introducing this mechanics into dislocation density evolution equations, the critical conditions for mechanical annealing under cyclic and monotonic loadings are discussed. Low-amplitude cyclic loading which strengthens the single crystal without seriously disturbing the structure has the potential applications in the manufacture of defect-free nano-devices.

The Reconstruction Problem Revisited

NASA Technical Reports Server (NTRS)

Suresh, Ambaby

1999-01-01

The role of reconstruction in avoiding oscillations in upwind schemes is reexamined, with the aim of providing simple, concise proofs. In one dimension, it is shown that if the reconstruction is any arbitrary function bounded by neighboring cell averages and increasing within a cell for increasing data, the resulting scheme is monotonicity preserving, even though the reconstructed function may have overshoots and undershoots at the cell edges and is in general not a monotone function. In the special case of linear reconstruction, it is shown that merely bounding the reconstruction between neighboring cell averages is sufficient to obtain a monotonicity preservinc,y scheme. In two dimensions, it is shown that some ID TVD limiters applied in each direction result in schemes that are not positivity preserving, i.e. do not give positive updates when the data are positive. A simple proof is given to show that if the reconstruction inside the cell is bounded by the neighboring cell averages (including corner neighbors), then the scheme is positivity preserving. A new limiter that enforces this condition but is not as dissipative as the Minmod limiter is also presented.

The complex association between the antioxidant defense system and clinical status in early psychosis

PubMed Central

García, Saínza; Alberich, Susana; Martínez-Cengotitabengoa, Mónica; Arango, Celso; Castro-Fornieles, Josefina; Parellada, Mara; Baeza, Inmaculada; Moreno, Carmen; Micó, Juan Antonio; Berrocoso, Esther; Graell, Montserrat; Otero, Soraya; Simal, Tatiana

2018-01-01

Oxidative stress is a pathophysiological mechanism potentially involved in psychiatric disorders. The objective of this study was to assess the relationship between total antioxidant status (TAS) and the functional status of patients with a first episode of psychosis at the onset of the disease. For this purpose, a sample of 70 patients aged between 9 and 17 years with a first episode of psychosis were followed up for a period of two years. Blood samples were drawn to measure TAS levels at three time points: at baseline, at one year, and at two years. Clinical symptoms and functioning were also assessed at the same time points using various scales. Linear regression analysis was performed to investigate the relationship between TAS and clinical status at each assessment, adjusting for potential confounding factors. The distribution of clinical variables was grouped in different percentiles to assess the dose-response in the relation between clinical variables and TAS. At baseline, patient's score on Children's Global Assessment Scale (CGAS) was directly and significantly associated with TAS with a monotonic increase in percentiles, and surprising this association was reversed after one and two years of follow-up with a monotonic decrease. In summary at the onset of the illness, TAS is positively related to clinical status, whereas as the illness progresses this correlation is reversed and becomes negative. This may be the result of an adaptive response. PMID:29698400

Alphabet Soup

ERIC Educational Resources Information Center

Rebholz, Joachim A.

2017-01-01

Graphing functions is an important topic in algebra and precalculus high school courses. The functions that are usually discussed include polynomials, rational, exponential, and trigonometric functions along with their inverses. These functions can be used to teach different aspects of function theory: domain, range, monotonicity, inverse…

Unimodal dynamical systems: Comparison principles, spreading speeds and travelling waves

NASA Astrophysics Data System (ADS)

Yi, Taishan; Chen, Yuming; Wu, Jianhong

Reaction diffusion equations with delayed nonlinear reaction terms are used as prototypes to motivate an appropriate abstract formulation of dynamical systems with unimodal nonlinearity. For such non-monotone dynamical systems, we develop a general comparison principle and show how this general comparison principle, coupled with some existing results for monotone dynamical systems, can be used to establish results on the asymptotic speeds of spread and travelling waves. We illustrate our main results by an integral equation which includes a nonlocal delayed reaction diffusion equation and a nonlocal delayed lattice differential system in an unbounded domain, with the non-monotone nonlinearities including the Ricker birth function and the Mackey-Glass hematopoiesis feedback.

Niche modelling of marsh plants based on occurrence and abundance data.

PubMed

Lou, Yanjing; Gao, Chuanyu; Pan, Yanwen; Xue, Zhenshan; Liu, Ying; Tang, Zhanhui; Jiang, Ming; Lu, Xianguo; Rydin, Håkan

2018-03-01

The information of species' response (optimum or critical limits along environmental gradients) is a key to understanding ecological questions and to design management plans. A large number of plots (762) from 70 transects of 13 wetland sites in Northeast China were sampled along flooding gradient from marsh to wet meadow. Species response (abundance and occurrence) to flooding were modelled with Generalized Additive Models for 21 dominant plant species. We found that 20 of 21 species showed a significant response to flooding for the occurrence and abundance models, and four types of response were found: monotonically increasing, monotonically decreasing, skewed unimodal and symmetric unimodal. The species with monotonically increasing response have the deepest flooding optimum and widest niche width, followed by those with unimodal curve, and the monotonically decreasing ones have the smallest values. The optima and niche width (whether based on occurrence or abundance models) both significantly correlated with the frequency, but not with mean abundance. Abundance models outperformed occurrence models based on goodness of fit. The abundance models predicted a rather sharp shift from dominance of helophytes (Carex pseudo-curaica and C. lasiocarpa) to wet meadow species (Calamagrostis angustifolia and Carex appendiculata) if water levels drop from about 10cm above soil surface to below the surface. The defined optima and niche width based on the abundance models can be applied to better instruct restoration management. Given the time required to collect abundance data, an efficient strategy could be to monitor occurrence in many plots and abundance in a subset of these. Copyright © 2017 Elsevier B.V. All rights reserved.

Optical Spectra of Extrasolar Giant Planets

NASA Technical Reports Server (NTRS)

Heap, Sara R.; Hubeny, Ivan; Sudarsky, David; Burrows, Adam

2004-01-01

The flux distribution of a planet relative to its host star is a critical quantity for planning space observatories to detect and characterize extrasolar giant planets (EGP's). In this paper, we present optical planet-star contrasts of Jupiter-mass planets as a function of stellar type, orbital distance, and planetary cloud characteristics. As originally shown by Sudarsky et al. (2000, 2003), the phaseaveraged brightness of an EGP does not necessarily decrease monotonically with greater orbital distance because of changes in its albedo and absorption spectrum at lower temperatures. We apply our results to Eclipse, a 1.8-m optical telescope + coronograph to be proposed as a NASA Discovery mission later this year.

Archimedes' principle in fluidized granular systems.

PubMed

Huerta, D A; Sosa, Victor; Vargas, M C; Ruiz-Suárez, J C

2005-09-01

We fluidize a granular bed in a rectangular container by injecting energy through the lateral walls with high-frequency sinusoidal horizontal vibrations. In this way, the bed is brought to a steady state with no convection. We measured buoyancy forces on light spheres immersed in the bed and found that they obey Archimedes' principle. The buoyancy forces decrease when we reduce the injected energy. By measuring ascension velocities as a function of gamma, we can evaluate the frictional drag of the bed; its exponential dependence agrees very well with previous findings. Rising times of the intruders ascending through the bed were also measured, they increase monotonically as we increase the density.

Galileo and optical illusion

NASA Astrophysics Data System (ADS)

Parker, Gary D.

1986-03-01

Galileo's earliest telescopic measurements are of sufficient quality that their detailed analysis yields scientifically interesting and pedagogically useful results. An optical illusion strongly influences Galileo's observations of Jupiter's moons, as published in the Starry Messenger. A simple procedure identifies individual satellites with sufficient reliability to demonstrate that Galileo regularly underestimated satellite brightness and overestimated elongation when a satellite was very close to Jupiter. The probability of underestimation is a monotonically decreasing function of separation angle, both for Galileo and for viewers of a laboratory simulation of the Jupiter ``starfield'' viewed by Galileo. Analysis of Galileo's records and a simple simulation experiment appropriate to undergraduate courses clarify the scientific problems facing Galileo in interpreting his observations.

Novel self-organization mechanism in ultrathin liquid films: theory and experiment.

PubMed

Trice, Justin; Favazza, Christopher; Thomas, Dennis; Garcia, Hernando; Kalyanaraman, Ramki; Sureshkumar, Radhakrishna

2008-07-04

When an ultrathin metal film of thickness h (<20 nm) is melted by a nanosecond pulsed laser, the film temperature is a nonmonotonic function of h and achieves its maximum at a certain thickness h*. This is a consequence of the h and time dependence of energy absorption and heat flow. Linear stability analysis and nonlinear dynamical simulations that incorporate such intrinsic interfacial thermal gradients predict a characteristic pattern length scale Lambda that decreases for h>h*, in contrast to the classical spinodal dewetting behavior where Lambda increases monotonically as h2. These predictions agree well with experimental observations for Co and Fe films on SiO2.

Continuous-variable quantum teleportation in bosonic structured environments

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

He Guangqiang; Zhang Jingtao; Zhu Jun

2011-09-15

The effects of dynamics of continuous-variable entanglement under the various kinds of environments on quantum teleportation are quantitatively investigated. Only under assumption of the weak system-reservoir interaction, the evolution of teleportation fidelity is analytically derived and is numerically plotted in terms of environment parameters including reservoir temperature and its spectral density, without Markovian and rotating wave approximations. We find that the fidelity of teleportation is a monotonically decreasing function for Markovian interaction in Ohmic-like environments, while it oscillates for non-Markovian ones. According to the dynamical laws of teleportation, teleportation with better performances can be implemented by selecting the appropriate time.

Impulsive And Long Duration High-Energy Gamma-Ray Emission From The Very Bright 2012 March 7 Solar Flares

DOE PAGES

Ajello, M.

2014-06-10

The Fermi Large Area Telescope (LAT) observed two bright X-class solar ares on 2012 March 7, and detected gamma-rays up to 4 GeV. We detected gamma-rays both during the impulsive and temporally-extended emission phases, with emission above 100 MeV lasting for approximately 20 hours. Accurate localization of the gamma-ray production site(s) coincide with the solar active region from which X-ray emissions associated with these ares originated. Our analysis of the > 100 MeV gamma-ray emission shows a relatively rapid monotonic decrease in flux during the first hour of the impulsive phase, and a much slower, almost monotonic decrease in fluxmore » for the next 20 hours. The spectra can be adequately described by a power law with a high energy exponential cutoff, or as resulting from the decay of neutral pions produced by accelerated protons and ions with an isotropic power-law energy distribution. The required proton spectrum has a number index 3, with minor variations during the impulsive phase, while during the temporally extended phase the spectrum softens monotonically, starting with index 4. The > 30 MeV proton flux and spectra observed near the Earth by the GOES satellites also show a monotonic flux decrease and spectral softening during the extended phase, but with a harder spectrum, with index 3. Based on the Fermi-LAT and GOES observations of the flux and spectral evolution of these bright ares, we explore the relative merits of prompt and continuous acceleration scenarios, hadronic and leptonic emission processes, and acceleration at the solar corona by the fast Coronal Mass Ejections (CME) as explanations for the observations. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona which penetrate the lower solar atmosphere and produce pions that decay into gamma-rays.« less

Impulsive And Long Duration High-Energy Gamma-Ray Emission From The Very Bright 2012 March 7 Solar Flares

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

Ajello, M.

The Fermi Large Area Telescope (LAT) observed two bright X-class solar ares on 2012 March 7, and detected gamma-rays up to 4 GeV. We detected gamma-rays both during the impulsive and temporally-extended emission phases, with emission above 100 MeV lasting for approximately 20 hours. Accurate localization of the gamma-ray production site(s) coincide with the solar active region from which X-ray emissions associated with these ares originated. Our analysis of the > 100 MeV gamma-ray emission shows a relatively rapid monotonic decrease in flux during the first hour of the impulsive phase, and a much slower, almost monotonic decrease in fluxmore » for the next 20 hours. The spectra can be adequately described by a power law with a high energy exponential cutoff, or as resulting from the decay of neutral pions produced by accelerated protons and ions with an isotropic power-law energy distribution. The required proton spectrum has a number index 3, with minor variations during the impulsive phase, while during the temporally extended phase the spectrum softens monotonically, starting with index 4. The > 30 MeV proton flux and spectra observed near the Earth by the GOES satellites also show a monotonic flux decrease and spectral softening during the extended phase, but with a harder spectrum, with index 3. Based on the Fermi-LAT and GOES observations of the flux and spectral evolution of these bright ares, we explore the relative merits of prompt and continuous acceleration scenarios, hadronic and leptonic emission processes, and acceleration at the solar corona by the fast Coronal Mass Ejections (CME) as explanations for the observations. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona which penetrate the lower solar atmosphere and produce pions that decay into gamma-rays.« less

Incorporating nonlinearity into mediation analyses.

PubMed

Knafl, George J; Knafl, Kathleen A; Grey, Margaret; Dixon, Jane; Deatrick, Janet A; Gallo, Agatha M

2017-03-21

Mediation is an important issue considered in the behavioral, medical, and social sciences. It addresses situations where the effect of a predictor variable X on an outcome variable Y is explained to some extent by an intervening, mediator variable M. Methods for addressing mediation have been available for some time. While these methods continue to undergo refinement, the relationships underlying mediation are commonly treated as linear in the outcome Y, the predictor X, and the mediator M. These relationships, however, can be nonlinear. Methods are needed for assessing when mediation relationships can be treated as linear and for estimating them when they are nonlinear. Existing adaptive regression methods based on fractional polynomials are extended here to address nonlinearity in mediation relationships, but assuming those relationships are monotonic as would be consistent with theories about directionality of such relationships. Example monotonic mediation analyses are provided assessing linear and monotonic mediation of the effect of family functioning (X) on a child's adaptation (Y) to a chronic condition by the difficulty (M) for the family in managing the child's condition. Example moderated monotonic mediation and simulation analyses are also presented. Adaptive methods provide an effective way to incorporate possibly nonlinear monotonicity into mediation relationships.

Surfactants non-monotonically modify the onset of Faraday waves

NASA Astrophysics Data System (ADS)

Strickland, Stephen; Shearer, Michael; Daniels, Karen

2017-11-01

When a water-filled container is vertically vibrated, subharmonic Faraday waves emerge once the driving from the vibrations exceeds viscous dissipation. In the presence of an insoluble surfactant, a viscous boundary layer forms at the contaminated surface to balance the Marangoni and Boussinesq stresses. For linear gravity-capillary waves in an undriven fluid, the surfactant-induced boundary layer increases the amount of viscous dissipation. In our analysis and experiments, we consider whether similar effects occur for nonlinear Faraday (gravity-capillary) waves. Assuming a finite-depth, infinite-breadth, low-viscosity fluid, we derive an analytic expression for the onset acceleration up to second order in ɛ =√{ 1 / Re } . This expression allows us to include fluid depth and driving frequency as parameters, in addition to the Marangoni and Boussinesq numbers. For millimetric fluid depths and driving frequencies of 30 to 120 Hz, our analysis recovers prior numerical results and agrees with our measurements of NBD-PC surfactant on DI water. In both case, the onset acceleration increases non-monotonically as a function of Marangoni and Boussinesq numbers. For shallower systems, our model predicts that surfactants could decrease the onset acceleration. DMS-0968258.

Critical mass of public goods and its coevolution with cooperation

NASA Astrophysics Data System (ADS)

Shi, Dong-Mei; Wang, Bing-Hong

2017-07-01

In this study, the enhancing parameter represented the value of the public goods to the public in public goods game, and was rescaled to a Fermi-Dirac distribution function of critical mass. Public goods were divided into two categories, consumable and reusable public goods, and their coevolution with cooperative behavior was studied. We observed that for both types of public goods, cooperation was promoted as the enhancing parameter increased when the value of critical mass was not very large. An optimal value of critical mass which led to the best cooperation was identified. We also found that cooperations emerged earlier for reusable public goods, and defections became extinct earlier for the consumable public goods. Moreover, we observed that a moderate depreciation rate for public goods resulted in an optimal cooperation, and this range became wider as the enhancing parameter increased. The noise influence on cooperation was studied, and it was shown that cooperation density varied non-monotonically as noise amplitude increased for reusable public goods, whereas decreased monotonically for consumable public goods. Furthermore, existence of the optimal critical mass was also identified in other three regular networks. Finally, simulation results were utilized to analyze the provision of public goods in detail.

Exploring spatial and temporal variations of cadmium concentrations in pacific oysters from british columbia.

PubMed

Feng, Cindy Xin; Cao, Jiguo; Bendell, Leah

2011-09-01

Oysters from the Pacific Northwest coast of British Columbia, Canada, contain high levels of cadmium, in some cases exceeding some international food safety guidelines. A primary goal of this article is the investigation of the spatial and temporal variation in cadmium concentrations for oysters sampled from coastal British Columbia. Such information is important so that recommendations can be made as to where and when oysters can be cultured such that accumulation of cadmium within these oysters is minimized. Some modern statistical methods are applied to achieve this goal, including monotone spline smoothing, functional principal component analysis, and semi-parametric additive modeling. Oyster growth rates are estimated as the first derivatives of the monotone smoothing growth curves. Some important patterns in cadmium accumulation by oysters are observed. For example, most inland regions tend to have a higher level of cadmium concentration than most coastal regions, so more caution needs to be taken for shellfish aquaculture practices occurring in the inland regions. The semi-parametric additive modeling shows that oyster cadmium concentration decreases with oyster length, and oysters sampled at 7 m have higher average cadmium concentration than those sampled at 1 m. © 2010, The International Biometric Society.

Increasing accuracy in the interval analysis by the improved format of interval extension based on the first order Taylor series

NASA Astrophysics Data System (ADS)

Li, Yi; Xu, Yan Long

2018-05-01

When the dependence of the function on uncertain variables is non-monotonic in interval, the interval of function obtained by the classic interval extension based on the first order Taylor series will exhibit significant errors. In order to reduce theses errors, the improved format of the interval extension with the first order Taylor series is developed here considering the monotonicity of function. Two typical mathematic examples are given to illustrate this methodology. The vibration of a beam with lumped masses is studied to demonstrate the usefulness of this method in the practical application, and the necessary input data of which are only the function value at the central point of interval, sensitivity and deviation of function. The results of above examples show that the interval of function from the method developed by this paper is more accurate than the ones obtained by the classic method.

Principal Component Analysis Based Measure of Structural Holes

NASA Astrophysics Data System (ADS)

Deng, Shiguo; Zhang, Wenqing; Yang, Huijie

2013-02-01

Based upon principal component analysis, a new measure called compressibility coefficient is proposed to evaluate structural holes in networks. This measure incorporates a new effect from identical patterns in networks. It is found that compressibility coefficient for Watts-Strogatz small-world networks increases monotonically with the rewiring probability and saturates to that for the corresponding shuffled networks. While compressibility coefficient for extended Barabasi-Albert scale-free networks decreases monotonically with the preferential effect and is significantly large compared with that for corresponding shuffled networks. This measure is helpful in diverse research fields to evaluate global efficiency of networks.

Method of model reduction and multifidelity models for solute transport in random layered porous media

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

Xu, Zhijie; Tartakovsky, Alexandre M.

This work presents a hierarchical model for solute transport in bounded layered porous media with random permeability. The model generalizes the Taylor-Aris dispersion theory to stochastic transport in random layered porous media with a known velocity covariance function. In the hierarchical model, we represent (random) concentration in terms of its cross-sectional average and a variation function. We derive a one-dimensional stochastic advection-dispersion-type equation for the average concentration and a stochastic Poisson equation for the variation function, as well as expressions for the effective velocity and dispersion coefficient. We observe that velocity fluctuations enhance dispersion in a non-monotonic fashion: the dispersionmore » initially increases with correlation length λ, reaches a maximum, and decreases to zero at infinity. Maximum enhancement can be obtained at the correlation length about 0.25 the size of the porous media perpendicular to flow.« less

Impurity effects on electrical conductivity of doped bilayer graphene in the presence of a bias voltage

NASA Astrophysics Data System (ADS)

E, Lotfi; H, Rezania; B, Arghavaninia; M, Yarmohammadi

2016-07-01

We address the electrical conductivity of bilayer graphene as a function of temperature, impurity concentration, and scattering strength in the presence of a finite bias voltage at finite doping, beginning with a description of the tight-binding model using the linear response theory and Green’s function approach. Our results show a linear behavior at high doping for the case of high bias voltage. The effects of electron doping on the electrical conductivity have been studied via changing the electronic chemical potential. We also discuss and analyze how the bias voltage affects the temperature behavior of the electrical conductivity. Finally, we study the behavior of the electrical conductivity as a function of the impurity concentration and scattering strength for different bias voltages and chemical potentials respectively. The electrical conductivity is found to be monotonically decreasing with impurity scattering strength due to the increased scattering among electrons at higher impurity scattering strength.

Microstructure and antioxidative capacity of the microalgae mutant Chlorella PY-ZU1 during tilmicosin removal from wastewater under 15% CO2.

PubMed

Cheng, Jun; Ye, Qing; Yang, Zongbo; Yang, Weijuan; Zhou, Junhu; Cen, Kefa

2017-02-15

The response mechanisms of microalgal mutant Chlorella PY-ZU1 cells were investigated in their removal of antibiotic tilmicosin from wastewater under 15% CO 2 . Low concentrations (0.01-2mgL -1 ) of tilmicosin in wastewater stimulated the growth of microalgal cells, whereas high concentrations (5-50mgL -1 ) of tilmicosin significantly inhibited cell growth. When initial tilmicosin concentration increased from 0 to 50mgL -1 , fractal dimension of microalgal cells monotonically increased from 1.36 to 1.62 and cell size monotonically decreased from 4.86 to 3.75μm. In parallel, malondialdehyde content, which represented the degree of cellular oxidative damage, monotonically increased from 1.92×10 -7 to 7.07×10 -7 nmol cell -1 . Superoxide dismutase activity that represented cellular antioxidant capacity first increased from 2.59×10 -4 to the peak of 6.60×10 -4 U cell -1 , then gradually decreased to 2.39×10 -4 U cell -1 . The maximum tilmicosin removal efficiency of 99.8% by Chlorella PY-ZU1 was obtained at the initial tilmicosin concentration of 50mgL -1 . Copyright © 2016 Elsevier B.V. All rights reserved.

Contraction coefficients for noisy quantum channels

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

Hiai, Fumio, E-mail: hiai.fumio@gmail.com; Ruskai, Mary Beth, E-mail: ruskai@member.ams.org

Generalized relative entropy, monotone Riemannian metrics, geodesic distance, and trace distance are all known to decrease under the action of quantum channels. We give some new bounds on, and relationships between, the maximal contraction for these quantities.

Minimum-error quantum distinguishability bounds from matrix monotone functions: A comment on 'Two-sided estimates of minimum-error distinguishability of mixed quantum states via generalized Holevo-Curlander bounds' [J. Math. Phys. 50, 032106 (2009)

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

Tyson, Jon

2009-06-15

Matrix monotonicity is used to obtain upper bounds on minimum-error distinguishability of arbitrary ensembles of mixed quantum states. This generalizes one direction of a two-sided bound recently obtained by the author [J. Tyson, J. Math. Phys. 50, 032106 (2009)]. It is shown that the previously obtained special case has unique properties.

Decoding sound level in the marmoset primary auditory cortex.

PubMed

Sun, Wensheng; Marongelli, Ellisha N; Watkins, Paul V; Barbour, Dennis L

2017-10-01

Neurons that respond favorably to a particular sound level have been observed throughout the central auditory system, becoming steadily more common at higher processing areas. One theory about the role of these level-tuned or nonmonotonic neurons is the level-invariant encoding of sounds. To investigate this theory, we simulated various subpopulations of neurons by drawing from real primary auditory cortex (A1) neuron responses and surveyed their performance in forming different sound level representations. Pure nonmonotonic subpopulations did not provide the best level-invariant decoding; instead, mixtures of monotonic and nonmonotonic neurons provided the most accurate decoding. For level-fidelity decoding, the inclusion of nonmonotonic neurons slightly improved or did not change decoding accuracy until they constituted a high proportion. These results indicate that nonmonotonic neurons fill an encoding role complementary to, rather than alternate to, monotonic neurons. NEW & NOTEWORTHY Neurons with nonmonotonic rate-level functions are unique to the central auditory system. These level-tuned neurons have been proposed to account for invariant sound perception across sound levels. Through systematic simulations based on real neuron responses, this study shows that neuron populations perform sound encoding optimally when containing both monotonic and nonmonotonic neurons. The results indicate that instead of working independently, nonmonotonic neurons complement the function of monotonic neurons in different sound-encoding contexts. Copyright © 2017 the American Physiological Society.

Strain and electric field induced metallization in the GaX (X = N, P, As & Sb) monolayer

NASA Astrophysics Data System (ADS)

Bahuguna, Bhagwati Prasad; Saini, L. K.; Sharma, Rajesh O.; Tiwari, Brajesh

2018-05-01

We investigate the strain and electric field dependent electronic properties of two dimensional Ga-based group III-V monolayer from the first-principles approach within density functional theory. The energy bandgap of GaX monolayer increases upto the certain value of compressive strain and then decreases. On the other hand, the energy bandgap of GaX monolayer is monotonically decreased with increasing tensile strain and become metallic at the higher value. Furthermore, the perpendicular electric field decreases the energy band gap of unstrained GaX monolayer and shows semiconductor to metal transition. These results suggest that the nature of energy bands and value of energy bandgap in GaX monolayer can be tuned by the biaxial mechanical strain or perpendicular electrical field. Additionally, we have also studied the optical response of unstrained GaX monolayer in term of optical conductivity. These findings may provide valuable information to develop the Ga-based optoelectronic devices and further the understanding of the GaX monolayer.

CFD simulation of simultaneous monotonic cooling and surface heat transfer coefficient

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

Mihálka, Peter, E-mail: usarmipe@savba.sk; Matiašovský, Peter, E-mail: usarmat@savba.sk

The monotonic heating regime method for determination of thermal diffusivity is based on the analysis of an unsteady-state (stabilised) thermal process characterised by an independence of the space-time temperature distribution on initial conditions. At the first kind of the monotonic regime a sample of simple geometry is heated / cooled at constant ambient temperature. The determination of thermal diffusivity requires the determination rate of a temperature change and simultaneous determination of the first eigenvalue. According to a characteristic equation the first eigenvalue is a function of the Biot number defined by a surface heat transfer coefficient and thermal conductivity ofmore » an analysed material. Knowing the surface heat transfer coefficient and the first eigenvalue the thermal conductivity can be determined. The surface heat transport coefficient during the monotonic regime can be determined by the continuous measurement of long-wave radiation heat flow and the photoelectric measurement of the air refractive index gradient in a boundary layer. CFD simulation of the cooling process was carried out to analyse local convective and radiative heat transfer coefficients more in detail. Influence of ambient air flow was analysed. The obtained eigenvalues and corresponding surface heat transfer coefficient values enable to determine thermal conductivity of the analysed specimen together with its thermal diffusivity during a monotonic heating regime.« less

Longitudinal data analysis with non-ignorable missing data.

PubMed

Tseng, Chi-hong; Elashoff, Robert; Li, Ning; Li, Gang

2016-02-01

A common problem in the longitudinal data analysis is the missing data problem. Two types of missing patterns are generally considered in statistical literature: monotone and non-monotone missing data. Nonmonotone missing data occur when study participants intermittently miss scheduled visits, while monotone missing data can be from discontinued participation, loss to follow-up, and mortality. Although many novel statistical approaches have been developed to handle missing data in recent years, few methods are available to provide inferences to handle both types of missing data simultaneously. In this article, a latent random effects model is proposed to analyze longitudinal outcomes with both monotone and non-monotone missingness in the context of missing not at random. Another significant contribution of this article is to propose a new computational algorithm for latent random effects models. To reduce the computational burden of high-dimensional integration problem in latent random effects models, we develop a new computational algorithm that uses a new adaptive quadrature approach in conjunction with the Taylor series approximation for the likelihood function to simplify the E-step computation in the expectation-maximization algorithm. Simulation study is performed and the data from the scleroderma lung study are used to demonstrate the effectiveness of this method. © The Author(s) 2012.

Maximizing Submodular Functions under Matroid Constraints by Evolutionary Algorithms.

PubMed

Friedrich, Tobias; Neumann, Frank

2015-01-01

Many combinatorial optimization problems have underlying goal functions that are submodular. The classical goal is to find a good solution for a given submodular function f under a given set of constraints. In this paper, we investigate the runtime of a simple single objective evolutionary algorithm called (1 + 1) EA and a multiobjective evolutionary algorithm called GSEMO until they have obtained a good approximation for submodular functions. For the case of monotone submodular functions and uniform cardinality constraints, we show that the GSEMO achieves a (1 - 1/e)-approximation in expected polynomial time. For the case of monotone functions where the constraints are given by the intersection of K ≥ 2 matroids, we show that the (1 + 1) EA achieves a (1/k + δ)-approximation in expected polynomial time for any constant δ > 0. Turning to nonmonotone symmetric submodular functions with k ≥ 1 matroid intersection constraints, we show that the GSEMO achieves a 1/((k + 2)(1 + ε))-approximation in expected time O(n(k + 6)log(n)/ε.

Cancer risks after radiation exposure in middle age.

PubMed

Shuryak, Igor; Sachs, Rainer K; Brenner, David J

2010-11-03

Epidemiological data show that radiation exposure during childhood is associated with larger cancer risks compared with exposure at older ages. For exposures in adulthood, however, the relative risks of radiation-induced cancer in Japanese atomic bomb survivors generally do not decrease monotonically with increasing age of adult exposure. These observations are inconsistent with most standard models of radiation-induced cancer, which predict that relative risks decrease monotonically with increasing age at exposure, at all ages. We analyzed observed cancer risk patterns as a function of age at exposure in Japanese atomic bomb survivors by using a biologically based quantitative model of radiation carcinogenesis that incorporates both radiation induction of premalignant cells (initiation) and radiation-induced promotion of premalignant damage. This approach emphasizes the kinetics of radiation-induced initiation and promotion, and tracks the yields of premalignant cells before, during, shortly after, and long after radiation exposure. Radiation risks after exposure in younger individuals are dominated by initiation processes, whereas radiation risks after exposure at later ages are more influenced by promotion of preexisting premalignant cells. Thus, the cancer site-dependent balance between initiation and promotion determines the dependence of cancer risk on age at radiation exposure. For example, in terms of radiation induction of premalignant cells, a quantitative measure of the relative contribution of initiation vs promotion is 10-fold larger for breast cancer than for lung cancer. Reflecting this difference, radiation-induced breast cancer risks decrease with age at exposure at all ages, whereas radiation-induced lung cancer risks do not. For radiation exposure in middle age, most radiation-induced cancer risks do not, as often assumed, decrease with increasing age at exposure. This observation suggests that promotional processes in radiation carcinogenesis become increasingly important as the age at exposure increases. Radiation-induced cancer risks after exposure in middle age may be up to twice as high as previously estimated, which could have implications for occupational exposure and radiological imaging.

Nebular dead zone effects on the D/H ratio in chondrites and comets

NASA Astrophysics Data System (ADS)

Ali-Dib, Mohamad; Martin, R. G.; Petit, J.-M.; Mousis, O.; Vernazza, P.; Lunine, J. I.

2015-11-01

Comets and chondrites show non-monotonic behaviour of their Deuterium to Hydrogen (D/H) ratio as a function of their formation location from the Sun. This is difficult to explain with a classical protoplanetary disk model that has a decreasing temperature structure with radius from the Sun.We want to understand if a protoplanetary disc with a dead zone, a region of zero or low turbulence, can explain the measured D/H values in comets and chondrites. We use time snapshots of a vertically layered disk model with turbulent surface layers and a dead zone at the midplane. The disc has a non-monotonic temperature structure due to increased heating from self-gravity in the outer parts of the dead zone. We couple this to a D/H ratio evolution model in order to quantify the effect of such thermal profiles on D/H enrichment in the nebula.We find that the local temperature peak in the disk can explain the diversity in the D/H ratios of different chondritic families. This disk temperature profile leads to a non-monotonic D/H enrichment evolution, allowing these families to acquire their different D/H values while forming in close proximity. The formation order we infer for these families is compatible with that inferred from their water abundances. However, we find that even for very young disks, the thermal profile reversal is too close to the Sun to be relevant for comets.[1] Ali-Dib, M., Martin, R. G., Petit, J.-M., Mousis, O., Vernazza, P., and Lunine, J. I. (2015, in press A&A). arXiv:1508.00263.

Biexciton relaxation associated with dissociation into a surface polariton pair in semiconductor films

NASA Astrophysics Data System (ADS)

Mitsumori, Yasuyoshi; Matsuura, Shimpei; Uchiyama, Shoichi; Saito, Kentarao; Edamatsu, Keiichi; Nakayama, Masaaki; Ajiki, Hiroshi

2018-04-01

We study the biexciton relaxation process in CuCl films ranging from 6 to 200 nm. The relaxation time is measured as the dephasing time and the lifetime. We observe a unique thickness dependence of the biexciton relaxation time and also obtain an ultrafast relaxation time with a timescale as short as 100 fs, while the exciton lifetime monotonically decreases with increasing thickness. By analyzing the exciton-photon coupling energy for a surface polariton, we theoretically calculate the biexciton relaxation time as a function of the thickness. The calculated dependence qualitatively reproduces the observed relaxation time, indicating that the biexciton dissociation into a surface polariton pair is one of the major biexciton relaxation processes.

Inertial frictional ratchets and their load bearing efficiencies

NASA Astrophysics Data System (ADS)

Kharkongor, D.; Reenbohn, W. L.; Mahato, Mangal C.

2018-03-01

We investigate the performance of an inertial frictional ratchet in a sinusoidal potential driven by a sinusoidal external field. The dependence of the performance on the parameters of the sinusoidally varying friction, such as the mean friction coefficient and its phase difference with the potential, is studied in detail. Interestingly, under certain circumstances, the thermodynamic efficiency of the ratchet against an applied load shows a non-monotonic behaviour as a function of the mean friction coefficient. Also, in the large friction ranges, the efficiency is shown to increase with increasing applied load even though the corresponding ratchet current decreases as the applied load increases. These counterintuitive numerical results are explained in the text.

The Holographic F Theorem

NASA Astrophysics Data System (ADS)

Taylor, Marika; Woodhead, William

2017-12-01

The F theorem states that, for a unitary three dimensional quantum field theory, the F quantity defined in terms of the partition function on a three sphere is positive, stationary at fixed point and decreases monotonically along a renormalization group flow. We construct holographic renormalization group flows corresponding to relevant deformations of three-dimensional conformal field theories on spheres, working to quadratic order in the source. For these renormalization group flows, the F quantity at the IR fixed point is always less than F at the UV fixed point, but F increases along the RG flow for deformations by operators of dimension between 3/2 and 5/2. Therefore the strongest version of the F theorem is in general violated.

Tuning the Curie temperature of FeCo compounds by tetragonal distortion

NASA Astrophysics Data System (ADS)

Jakobsson, A.; Şaşıoǧlu, E.; Mavropoulos, Ph.; Ležaić, M.; Sanyal, B.; Bihlmayer, G.; Blügel, S.

2013-09-01

Combining density-functional theory calculations with a classical Monte Carlo method, we show that for B2-type FeCo compounds, tetragonal distortion gives rise to a strong reduction of the Curie temperature TC. The TC monotonically decreases from 1575 K (for c /a=1) to 940 K (for c /a=√2 ). We find that the nearest neighbor Fe-Co exchange interaction is sufficient to explain the c/a behavior of the TC. Combination of high magnetocrystalline anisotropy energy with a moderate TC value suggests tetragonal FeCo grown on the Rh substrate with c /a=1.24 to be a promising material for heat-assisted magnetic recording applications.

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

Zhuang, J. C.; Li, Z.; Xu, X.

We present a detailed investigation on the doping dependence of the upper critical field H{sub c2}(T) of FeSe{sub x}Te{sub 1−x} thin films (0.18 ≤ x ≤ 0.90) by measuring the electrical resistivity as a function of magnetic field. The H{sub c2}(T) curves exhibit a downturn behavior with decreasing temperature in all the samples, owing to the Pauli-limited effect (spin paramagnetic effect). The Pauli-limited effect on the upper critical field can be monotonically modulated by variation of the Se/Te composition. Our results show that Te-doping induced disorder and excess Fe atoms give rise to enhancement of the Pauli-limited effect.

A study of excess H-alpha emission in chromospherically active M dwarf

NASA Technical Reports Server (NTRS)

Young, Arthur; Skumanich, Andrew; Stauffer, John R.; Harlan, Eugene; Bopp, Bernard W.

1989-01-01

Spectroscopic observations from three observatories are combined to study the properties of the excess H-alpha emission which characterizes the most chromospherically active subset of the M dwarf stars, known as the dMe stars. It is demonstrated that the excess H-alpha luminosity from these stars is a monotonically decreasing function of their (R-I) color, and evidence is presented which suggests that the product of the mean surface brightness and the mean filling factor of the emissive regions is essentially constant with color. Another significant result of the study is a linear correlation between the excess luminosity in H-alpha and the coronal X-ray luminosity.

Free-layer size dependence of anisotropy field in nanoscale CoFeB/MgO magnetic tunnel junctions

NASA Astrophysics Data System (ADS)

Shinozaki, Motoya; Igarashi, Junta; Sato, Hideo; Ohno, Hideo

2018-04-01

We investigate free-layer size D dependence of effective anisotropy field in nanoscale CoFeB/MgO magnetic tunnel junctions by homodyne-detected ferromagnetic resonance. The effective anisotropy field HK\\text{eff} monotonically increases with decreasing D for a device with the reference-layer size much larger than the free-layer size. In contrast, HK\\text{eff} does not increase in a monotonic manner for a device with the reference-layer size comparable to the free-layer size. We reveal that the difference can be explained by the variation of the anisotropy field in the vicinity of the device edge.

Lidar inelastic multiple-scattering parameters of cirrus particle ensembles determined with geometrical-optics crystal phase functions.

PubMed

Reichardt, J; Hess, M; Macke, A

2000-04-20

Multiple-scattering correction factors for cirrus particle extinction coefficients measured with Raman and high spectral resolution lidars are calculated with a radiative-transfer model. Cirrus particle-ensemble phase functions are computed from single-crystal phase functions derived in a geometrical-optics approximation. Seven crystal types are considered. In cirrus clouds with height-independent particle extinction coefficients the general pattern of the multiple-scattering parameters has a steep onset at cloud base with values of 0.5-0.7 followed by a gradual and monotonic decrease to 0.1-0.2 at cloud top. The larger the scattering particles are, the more gradual is the rate of decrease. Multiple-scattering parameters of complex crystals and of imperfect hexagonal columns and plates can be well approximated by those of projected-area equivalent ice spheres, whereas perfect hexagonal crystals show values as much as 70% higher than those of spheres. The dependencies of the multiple-scattering parameters on cirrus particle spectrum, base height, and geometric depth and on the lidar parameters laser wavelength and receiver field of view, are discussed, and a set of multiple-scattering parameter profiles for the correction of extinction measurements in homogeneous cirrus is provided.

First-principles investigation of mechanical and electronic properties of tetragonal NbAl3 under tension

NASA Astrophysics Data System (ADS)

Jiao, Zhen; Liu, Qi-Jun; Liu, Fu-Sheng; Tang, Bin

2018-06-01

Using the density functional theory calculations, the mechanical and electronic properties of NbAl3 under different tensile loads were investigated. The calculated lattice parameters, elastic constants and mechanical properties (bulk modulus, shear modulus, Young's modulus, Poisson's ratio, Pugh's criterion and Cauchy's pressure) indicated that our results were in agreement with the published experimental and theoretical data at zero tension. With respect to NbAl3 under tension in this paper, the crystal structure was changed from tetragonal to orthorhombic under tension along the [100] and [101] directions. The NbAl3 crystal has been classified as brittle material under tension from 0 to 20 GPa. The obtained Young's modulus and Debye temperature monotonically decreased with increasing tension stress. Combining with mechanical and electronic properties in detail, the decreased mechanical properties were mainly due to the weakening of covalency.

Lattice model calculation of elastic and thermodynamic properties at high pressure and temperature. [for alkali halides in NaCl lattice

NASA Technical Reports Server (NTRS)

Demarest, H. H., Jr.

1972-01-01

The elastic constants and the entire frequency spectrum were calculated up to high pressure for the alkali halides in the NaCl lattice, based on an assumed functional form of the inter-atomic potential. The quasiharmonic approximation is used to calculate the vibrational contribution to the pressure and the elastic constants at arbitrary temperature. By explicitly accounting for the effect of thermal and zero point motion, the adjustable parameters in the potential are determined to a high degree of accuracy from the elastic constants and their pressure derivatives measured at zero pressure. The calculated Gruneisen parameter, the elastic constants and their pressure derivatives are in good agreement with experimental results up to about 600 K. The model predicts that for some alkali halides the Grunesen parameter may decrease monotonically with pressure, while for others it may increase with pressure, after an initial decrease.

Fast-kick-off monotonically convergent algorithm for searching optimal control fields

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

Liao, Sheng-Lun; Ho, Tak-San; Rabitz, Herschel

2011-09-15

This Rapid Communication presents a fast-kick-off search algorithm for quickly finding optimal control fields in the state-to-state transition probability control problems, especially those with poorly chosen initial control fields. The algorithm is based on a recently formulated monotonically convergent scheme [T.-S. Ho and H. Rabitz, Phys. Rev. E 82, 026703 (2010)]. Specifically, the local temporal refinement of the control field at each iteration is weighted by a fractional inverse power of the instantaneous overlap of the backward-propagating wave function, associated with the target state and the control field from the previous iteration, and the forward-propagating wave function, associated with themore » initial state and the concurrently refining control field. Extensive numerical simulations for controls of vibrational transitions and ultrafast electron tunneling show that the new algorithm not only greatly improves the search efficiency but also is able to attain good monotonic convergence quality when further frequency constraints are required. The algorithm is particularly effective when the corresponding control dynamics involves a large number of energy levels or ultrashort control pulses.« less

Effect of inhibitory feedback on correlated firing of spiking neural network.

PubMed

Xie, Jinli; Wang, Zhijie

2013-08-01

Understanding the properties and mechanisms that generate different forms of correlation is critical for determining their role in cortical processing. Researches on retina, visual cortex, sensory cortex, and computational model have suggested that fast correlation with high temporal precision appears consistent with common input, and correlation on a slow time scale likely involves feedback. Based on feedback spiking neural network model, we investigate the role of inhibitory feedback in shaping correlations on a time scale of 100 ms. Notably, the relationship between the correlation coefficient and inhibitory feedback strength is non-monotonic. Further, computational simulations show how firing rate and oscillatory activity form the basis of the mechanisms underlying this relationship. When the mean firing rate holds unvaried, the correlation coefficient increases monotonically with inhibitory feedback, but the correlation coefficient keeps decreasing when the network has no oscillatory activity. Our findings reveal that two opposing effects of the inhibitory feedback on the firing activity of the network contribute to the non-monotonic relationship between the correlation coefficient and the strength of the inhibitory feedback. The inhibitory feedback affects the correlated firing activity by modulating the intensity and regularity of the spike trains. Finally, the non-monotonic relationship is replicated with varying transmission delay and different spatial network structure, demonstrating the universality of the results.

Permeability Asymmetry in Composite Porous Ceramic Membranes

NASA Astrophysics Data System (ADS)

Kurcharov, I. M.; Laguntsov, N. I.; Uvarov, V. I.; Kurchatova, O. V.

The results from the investigation of transport characteristics and gas transport asymmetry in bilayer composite membranes are submitted. These membranes are produced by SHS method. Asymmetric effect and hysteresis of permeability in nanoporous membranes are detected. It's shown, that permeability ratio (asymmetry value of permeability) increases up to several times. The asymmetry of permeability usually decreases monotonically with the pressure decrease.

Global mountain topography and the fate of montane species under climate change

NASA Astrophysics Data System (ADS)

Elsen, Paul R.; Tingley, Morgan W.

2015-08-01

Increasing evidence indicates that species throughout the world are responding to climate change by shifting their geographic distributions. Although shifts can be directionally heterogeneous, they often follow warming temperatures polewards and upslope. Montane species are of particular concern in this regard, as they are expected to face reduced available area of occupancy and increased risk of extinction with upslope movements. However, this expectation hinges on the assumption that surface area decreases monotonically as species move up mountainsides. We analysed the elevational availability of surface area for a global data set containing 182 of the world's mountain ranges. Sixty-eight per cent of these mountain ranges had topographies in which area did not decrease monotonically with elevation. Rather, mountain range topographies exhibited four distinct area-elevation patterns: decreasing (32% of ranges), increasing (6%), a mid-elevation peak in area (39%), and a mid-elevation trough in area (23%). These findings suggest that many species, particularly those of foothills and lower montane zones, may encounter increases in available area as a result of shifting upslope. A deeper understanding of underlying mountain topography can inform conservation priorities by revealing where shifting species stand to undergo area increases, decreases and bottlenecks as they respond to climate change.

Membranes, mechanics, and intracellular transport

NASA Astrophysics Data System (ADS)

Parthasarathy, Raghuveer

2012-10-01

Cellular membranes are remarkable materials -- self-assembled, flexible, two-dimensional fluids. Understanding how proteins manipulate membrane curvature is crucial to understanding the transport of cargo in cells, yet the mechanical activities of trafficking proteins remain poorly understood. Using an optical-trap based assay involving dynamic deformation of biomimetic membranes, we have examined the behavior of Sar1, a key component of the COPII family of transport proteins. We find that Sar1 from yeast (S. cerevisiae) lowers membrane rigidity by up to 100% as a function of its concentration, thereby lowering the energetic cost of membrane deformation. Human Sar1 proteins can also lower the mechanical rigidity of the membranes to which they bind. However, unlike the yeast proteins, the rigidity is not a monotonically decreasing function of concentration but rather shows increased rigidity and decreased mobility at high concentrations that implies interactions between proteins. In addition to describing this study of membrane mechanics, I'll also discuss some topics relevant to a range of biophysical investigations, such as the insights provided by imaging methods and open questions in the dynamics of multicellular systems.

Value Iteration Adaptive Dynamic Programming for Optimal Control of Discrete-Time Nonlinear Systems.

PubMed

Wei, Qinglai; Liu, Derong; Lin, Hanquan

2016-03-01

In this paper, a value iteration adaptive dynamic programming (ADP) algorithm is developed to solve infinite horizon undiscounted optimal control problems for discrete-time nonlinear systems. The present value iteration ADP algorithm permits an arbitrary positive semi-definite function to initialize the algorithm. A novel convergence analysis is developed to guarantee that the iterative value function converges to the optimal performance index function. Initialized by different initial functions, it is proven that the iterative value function will be monotonically nonincreasing, monotonically nondecreasing, or nonmonotonic and will converge to the optimum. In this paper, for the first time, the admissibility properties of the iterative control laws are developed for value iteration algorithms. It is emphasized that new termination criteria are established to guarantee the effectiveness of the iterative control laws. Neural networks are used to approximate the iterative value function and compute the iterative control law, respectively, for facilitating the implementation of the iterative ADP algorithm. Finally, two simulation examples are given to illustrate the performance of the present method.

Characterizing the Cloud Decks of Luhman 16AB with Medium-resolution Spectroscopic Monitoring

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

Kellogg, Kendra; Metchev, Stanimir; Heinze, Aren

2017-11-01

We present results from a two-night R ∼ 4000 0.9–2.5 μ m spectroscopic monitoring campaign of Luhman 16AB (L7.5 + T0.5). We assess the variability amplitude as a function of pressure level in the atmosphere of Luhman 16B: the more variable of the two components. The amplitude decreases monotonically with decreasing pressure, indicating that the source of variability—most likely patchy clouds—lies in the lower atmosphere. An unexpected result is that the strength of the K i absorption is higher in the faint state of Luhman 16B and lower in the bright state. We conclude that either the abundance of Kmore » i increases when the clouds roll in, potentially because of additional K i in the cloud itself, or that the temperature–pressure profile changes. We reproduce the change in K i absorption strengths with combinations of spectral templates to represent the bright and the faint variability states. These are dominated by a warmer L8 or L9 component, with a smaller contribution from a cooler T1 or T2 component. The success of this approach argues that the mechanism responsible for brown dwarf variability is also behind the diverse spectral morphology across the L-to-T transition. We further suggest that the L9–T1 part of the sequence represents a narrow but random ordering of effective temperatures and cloud fractions, obscured by the monotonic progression in methane absorption strength.« less

Impact of surface porosity and topography on the mechanical behavior of high strength biomedical polymers.

PubMed

Evans, Nathan T; Irvin, Cameron W; Safranski, David L; Gall, Ken

2016-06-01

The ability to control the surface topography of orthopedic implant materials is desired to improve osseointegration but is often at the expense of mechanical performance in load bearing environments. Here we investigate the effects of surface modifications, roughness and porosity, on the mechanical properties of a set of polymers with diverse chemistry and structure. Both roughness and surface porosity resulted in samples with lower strength, failure strain and fatigue life due to stress concentrations at the surface; however, the decrease in ductility and fatigue strength were greater than the decrease in monotonic strength. The fatigue properties of the injection molded polymers did not correlate with yield strength as would be traditionally observed in metals. Rather, the fatigue properties and the capacity to maintain properties with the introduction of surface porosity correlated with the fracture toughness of the polymers. Polymer structure impacted the materials relative capacity to maintain monotonic and cyclic properties in the face of surface texture and porosity. Generally, amorphous polymers with large ratios of upper to lower yield points demonstrated a more significant drop in ductility and fatigue strength with the introduction of porosity compared to crystalline polymers with smaller ratios in their upper to lower yield strength. The latter materials have more effective dissipation mechanisms to minimize the impact of surface porosity on both monotonic and cyclic damage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Automated lung tumor segmentation for whole body PET volume based on novel downhill region growing

NASA Astrophysics Data System (ADS)

Ballangan, Cherry; Wang, Xiuying; Eberl, Stefan; Fulham, Michael; Feng, Dagan

2010-03-01

We propose an automated lung tumor segmentation method for whole body PET images based on a novel downhill region growing (DRG) technique, which regards homogeneous tumor hotspots as 3D monotonically decreasing functions. The method has three major steps: thoracic slice extraction with K-means clustering of the slice features; hotspot segmentation with DRG; and decision tree analysis based hotspot classification. To overcome the common problem of leakage into adjacent hotspots in automated lung tumor segmentation, DRG employs the tumors' SUV monotonicity features. DRG also uses gradient magnitude of tumors' SUV to improve tumor boundary definition. We used 14 PET volumes from patients with primary NSCLC for validation. The thoracic region extraction step achieved good and consistent results for all patients despite marked differences in size and shape of the lungs and the presence of large tumors. The DRG technique was able to avoid the problem of leakage into adjacent hotspots and produced a volumetric overlap fraction of 0.61 +/- 0.13 which outperformed four other methods where the overlap fraction varied from 0.40 +/- 0.24 to 0.59 +/- 0.14. Of the 18 tumors in 14 NSCLC studies, 15 lesions were classified correctly, 2 were false negative and 15 were false positive.

U-shaped development: an old but unsolved problem.

PubMed

Pauls, Franz; Macha, Thorsten; Petermann, Franz

2013-01-01

Even today the investigation of U-shaped functions in human development is of considerable importance for different domains of Developmental Psychology. More and more scientific researchers focus their efforts on the challenge to describe and explain the phenomenon by identifying those skills and abilities being affected. The impact of U-shaped functions on diagnostic decision-making and on therapeutic treatment programs highlights the importance of understanding the nature of non-monotonic development. The present article therefore addresses the relevant questions of how U-shaped functions are defined in theory, in which developmental domains such non-monotonic growth curves are suggested to occur, and which implications there are for future methodology and diagnostic practice. Finally, it is recommended to clearly identify those interactions between proximal and distal subcomponents which are expected to contribute to a U-shaped development.

U-Shaped Development: An Old but Unsolved Problem

PubMed Central

Pauls, Franz; Macha, Thorsten; Petermann, Franz

2013-01-01

Even today the investigation of U-shaped functions in human development is of considerable importance for different domains of Developmental Psychology. More and more scientific researchers focus their efforts on the challenge to describe and explain the phenomenon by identifying those skills and abilities being affected. The impact of U-shaped functions on diagnostic decision-making and on therapeutic treatment programs highlights the importance of understanding the nature of non-monotonic development. The present article therefore addresses the relevant questions of how U-shaped functions are defined in theory, in which developmental domains such non-monotonic growth curves are suggested to occur, and which implications there are for future methodology and diagnostic practice. Finally, it is recommended to clearly identify those interactions between proximal and distal subcomponents which are expected to contribute to a U-shaped development. PMID:23750146

Topography of sound level representation in the FM sweep selective region of the pallid bat auditory cortex.

PubMed

Measor, Kevin; Yarrow, Stuart; Razak, Khaleel A

2018-05-26

Sound level processing is a fundamental function of the auditory system. To determine how the cortex represents sound level, it is important to quantify how changes in level alter the spatiotemporal structure of cortical ensemble activity. This is particularly true for echolocating bats that have control over, and often rapidly adjust, call level to actively change echo level. To understand how cortical activity may change with sound level, here we mapped response rate and latency changes with sound level in the auditory cortex of the pallid bat. The pallid bat uses a 60-30 kHz downward frequency modulated (FM) sweep for echolocation. Neurons tuned to frequencies between 30 and 70 kHz in the auditory cortex are selective for the properties of FM sweeps used in echolocation forming the FM sweep selective region (FMSR). The FMSR is strongly selective for sound level between 30 and 50 dB SPL. Here we mapped the topography of level selectivity in the FMSR using downward FM sweeps and show that neurons with more monotonic rate level functions are located in caudomedial regions of the FMSR overlapping with high frequency (50-60 kHz) neurons. Non-monotonic neurons dominate the FMSR, and are distributed across the entire region, but there is no evidence for amplitopy. We also examined how first spike latency of FMSR neurons change with sound level. The majority of FMSR neurons exhibit paradoxical latency shift wherein the latency increases with sound level. Moreover, neurons with paradoxical latency shifts are more strongly level selective and are tuned to lower sound level than neurons in which latencies decrease with level. These data indicate a clustered arrangement of neurons according to monotonicity, with no strong evidence for finer scale topography, in the FMSR. The latency analysis suggests mechanisms for strong level selectivity that is based on relative timing of excitatory and inhibitory inputs. Taken together, these data suggest how the spatiotemporal spread of cortical activity may represent sound level. Copyright © 2018. Published by Elsevier B.V.

Atomistic simulation of the influence of Cr on the mobility of the edge dislocation in Fe(Cr) alloys

NASA Astrophysics Data System (ADS)

Hafez Haghighat, S. M.; Terentyev, D.; Schäublin, R.

2011-10-01

In this work Fe-Cr compounds, as model alloys for the ferritic base steels that are considered as main candidates for the structural materials of the future fusion reactors, are studied using molecular dynamics simulations. The Cr or so-called α' precipitates, which are obstacles to dislocations, affect mechanical properties, leading to hardening and loss of ductility. The flow stress to move an edge dislocation in a Cr solid solution in pure Fe is studied as a function of Cr content. The strength of a nanometric Cr precipitate as obstacle to an edge dislocation in pure Fe is investigated as a function of its Cr content. Results show that with increasing Cr content the precipitate obstacle strength increases, with a strong sensitivity to the local atomic order. Temperature induces a monotonic decrease of the flow stress of the Cr solid solution and of the Cr precipitate obstacle strength.

Operational quantification of continuous-variable correlations.

PubMed

Rodó, Carles; Adesso, Gerardo; Sanpera, Anna

2008-03-21

We quantify correlations (quantum and/or classical) between two continuous-variable modes as the maximal number of correlated bits extracted via local quadrature measurements. On Gaussian states, such "bit quadrature correlations" majorize entanglement, reducing to an entanglement monotone for pure states. For non-Gaussian states, such as photonic Bell states, photon-subtracted states, and mixtures of Gaussian states, the bit correlations are shown to be a monotonic function of the negativity. This quantification yields a feasible, operational way to measure non-Gaussian entanglement in current experiments by means of direct homodyne detection, without a complete state tomography.

Backscatter and attenuation properties of mammalian brain tissues

NASA Astrophysics Data System (ADS)

Wijekularatne, Pushpani Vihara

Traumatic Brain Injury (TBI) is a common category of brain injuries, which contributes to a substantial number of deaths and permanent disability all over the world. Ultrasound technology plays a major role in tissue characterization due to its low cost and portability that could be used to bridge a wide gap in the TBI diagnostic process. This research addresses the ultrasonic properties of mammalian brain tissues focusing on backscatter and attenuation. Orientation dependence and spatial averaging of data were analyzed using the same method resulting from insertion of tissue sample between a transducer and a reference reflector. Apparent backscatter transfer function (ABTF) at 1 to 10 MHz, attenuation coefficient and backscatter coefficient (BSC) at 1 to 5 MHz frequency ranges were measured on ovine brain tissue samples. The resulting ABTF was a monotonically decreasing function of frequency and the attenuation coefficient and BSC generally were increasing functions of frequency, results consistent with other soft tissues such as liver, blood and heart.

Freeze-out dynamics via charged kaon femtoscopy in sNN=200 GeV central Au + Au collisions

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bhattarai; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bruna, E.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks; Ding, F.; Dion, A.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Gliske, S.; Grebenyuk, O. G.; Grosnick, D.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jena, C.; Judd, E. G.; Kabana, S.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Kikola, D. P.; Kiryluk, J.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Novak, J.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Powell, C. B.; Pruneau, C.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, B.; Schmitz, N.; Schuster, T. R.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, B.; Sharma, M.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A., Jr.; Varma, R.; Vasconcelos, G. M. S.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Yan; Yang, C.; Yang, Y.; Yang, Y.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.

2013-09-01

We present measurements of three-dimensional correlation functions of like-sign, low-transverse-momentum kaon pairs from sNN=200 GeV Au+Au collisions. A Cartesian surface-spherical harmonic decomposition technique was used to extract the kaon source function. The latter was found to have a three-dimensional Gaussian shape and can be adequately reproduced by Therminator event-generator simulations with resonance contributions taken into account. Compared to the pion one, the kaon source function is generally narrower and does not have the long tail along the pair transverse momentum direction. The kaon Gaussian radii display a monotonic decrease with increasing transverse mass mT over the interval of 0.55≤mT≤1.15 GeV/c2. While the kaon radii are adequately described by the mT -scaling in the outward and sideward directions, in the longitudinal direction the lowest mT value exceeds the expectations from a pure hydrodynamical model prediction.

Minimization of the Renyi entropy production in the stationary states of the Brownian process with matched death and birth rates.

PubMed

Cybulski, Olgierd; Babin, Volodymyr; Hołyst, Robert

2004-01-01

We analyze the Fleming-Viot process. The system is confined in a box, whose boundaries act as a sink of Brownian particles. The death rate at the boundaries is matched by the branching (birth) rate in the system and thus the number of particles is kept constant. We show that such a process is described by the Renyi entropy whose production is minimized in the stationary state. The entropy production in this process is a monotonically decreasing function of time irrespective of the initial conditions. The first Laplacian eigenvalue is shown to be equal to the Renyi entropy production in the stationary state. As an example we simulate the process in a two-dimensional box.

Optimal matrix rigidity for stress fiber polarization in stem cells

PubMed Central

Rehfeldt, F.; Brown, A. E. X.; Discher, D. E.; Safran, S. A.

2010-01-01

The shape and differentiation of human mesenchymal stem cells is especially sensitive to the rigidity of their environment; the physical mechanisms involved are unknown. A theoretical model and experiments demonstrate here that the polarization/alignment of stress-fibers within stem cells is a non-monotonic function of matrix rigidity. We treat the cell as an active elastic inclusion in a surrounding matrix whose polarizability, unlike dead matter, depends on the feedback of cellular forces that develop in response to matrix stresses. The theory correctly predicts the monotonic increase of the cellular forces with the matrix rigidity and the alignment of stress-fibers parallel to the long axis of cells. We show that the anisotropy of this alignment depends non-monotonically on matrix rigidity and demonstrate it experimentally by quantifying the orientational distribution of stress-fibers in stem cells. These findings offer a first physical insight for the dependence of stem cell differentiation on tissue elasticity. PMID:20563235

Brain 'talks over' boring quotes: top-down activation of voice-selective areas while listening to monotonous direct speech quotations.

PubMed

Yao, Bo; Belin, Pascal; Scheepers, Christoph

2012-04-15

In human communication, direct speech (e.g., Mary said, "I'm hungry") is perceived as more vivid than indirect speech (e.g., Mary said that she was hungry). This vividness distinction has previously been found to underlie silent reading of quotations: Using functional magnetic resonance imaging (fMRI), we found that direct speech elicited higher brain activity in the temporal voice areas (TVA) of the auditory cortex than indirect speech, consistent with an "inner voice" experience in reading direct speech. Here we show that listening to monotonously spoken direct versus indirect speech quotations also engenders differential TVA activity. This suggests that individuals engage in top-down simulations or imagery of enriched supra-segmental acoustic representations while listening to monotonous direct speech. The findings shed new light on the acoustic nature of the "inner voice" in understanding direct speech. Copyright © 2012 Elsevier Inc. All rights reserved.

Self-deflection of a bright soliton in a separate bright-dark spatial soliton pair based on a higher-order space charge field

NASA Astrophysics Data System (ADS)

Liu, Jin-Song; Hao, Zhong-Hua

2003-10-01

The self-deflection of a bright solitary beam can be controlled by a dark solitary beam via a parametric coupling effect between the bright and dark solitary beams in a separate bright-dark spatial soliton pair supported by an unbiased series photorefractive crystal circuit. The spatial shift of the bright solitary beam centre as a function of the input intensity of the dark solitary beam (hat rho) is investigated by taking into account the higher-order space charge field in the dynamics of the bright solitary beam via both numerical and perturbation methods under steady-state conditions. The deflection amount (Deltas0), defined as the value of the spatial shift at the output surface of the crystal, is a monotonic and nonlinear function of hat rho. When hat rho is weak or strong enough, Deltas0 is, in fact, unchanged with hat rho, whereas Deltas0 increases or decreases monotonically with hat rho in a middle range of hat rho. The corresponding variation range (deltas) depends strongly on the value of the input intensity of the bright solitary beam (r). There are some peak and valley values in the curve of deltas versus r under some conditions. When hat rho increases, the bright solitary beam can scan toward both the direction same as and opposite to the crystal's c-axis. Whether the direction is the same as or opposite to the c-axis depends on the parameter values and configuration of the crystal circuit, as well as the value of r. Some potential applications are discussed.

The importance of charge-transfer interactions in determining chromophoric dissolved organic matter (CDOM) optical and photochemical properties.

PubMed

Sharpless, Charles M; Blough, Neil V

2014-04-01

Absorption of sunlight by chromophoric dissolved natural organic matter (CDOM) is environmentally significant because it controls photic zone depth and causes photochemistry that affects elemental cycling and contaminant fate. Both the optics (absorbance and fluorescence) and photochemistry of CDOM display unusual properties that cannot easily be ascribed to a superposition of individual chromophores. These include (i) broad, unstructured absorbance that decreases monotonically well into the visible and near IR, (ii) fluorescence emission spectra that all fall into a single envelope regardless of the excitation wavelength, and (iii) photobleaching and photochemical quantum yields that decrease monotonically with increasing wavelength. In contrast to a simple superposition model, these phenomena and others can be reasonably well explained by a physical model in which charge-transfer interactions between electron donating and accepting chromophores within the CDOM control the optical and photophysical properties. This review summarizes current understanding of the processes underlying CDOM photophysics and photochemistry as well as their physical basis.

Analysis of condition for uniform lighting generated by array of light emitting diodes with large view angle.

PubMed

Qin, Zong; Wang, Kai; Chen, Fei; Luo, Xiaobing; Liu, Sheng

2010-08-02

In this research, the condition for uniform lighting generated by array of LEDs with large view angle was studied. The luminous intensity distribution of LED is not monotone decreasing with view angle. A LED with freeform lens was designed as an example for analysis. In a system based on LEDs designed in house with a thickness of 20mm and rectangular arrangement, the condition for uniform lighting was derived and the analytical results demonstrated that the uniformity was not decreasing monotonously with the increasing of LED-to-LED spacing. The illuminance uniformities were calculated with Monte Carlo ray tracing simulations and the uniformity was found to increase with the increasing of certain LED-to-LED spacings anomalously. Another type of large view angle LED and different arrangements were discussed in addition. Both analysis and simulation results showed that the method is available for LED array lighting system design on the basis of large view angle LED..

Phase Transformation Evolution in NiTi Shape Memory Alloy under Cyclic Nanoindentation Loadings at Dissimilar Rates

PubMed Central

Amini, Abbas; Cheng, Chun; Kan, Qianhua; Naebe, Minoo; Song, Haisheng

2013-01-01

Hysteresis energy decreased significantly as nanocrystalline NiTi shape memory alloy was under triangular cyclic nanoindentation loadings at high rate. Jagged curves evidenced discrete stress relaxations. With a large recovery state of maximum deformation in each cycle, this behavior concluded in several nucleation sites of phase transformation in stressed bulk. Additionally, the higher initial propagation velocity of interface and thermal activation volume, and higher levels of phase transition stress in subsequent cycles explained the monotonic decreasing trend of dissipated energy. In contrast, the dissipated energy showed an opposite increasing trend during triangular cyclic loadings at a low rate and 60 sec holding time after each unloading stage. Due to the isothermal loading rate and the holding time, a major part of the released latent heat was transferred during the cyclic loading resulting in an unchanged phase transition stress. This fact with the reorientation phenomenon explained the monotonic increasing trend of hysteresis energy. PMID:24336228

Combined first-principles and model Hamiltonian study of the perovskite series R MnO 3 (R =La ,Pr ,Nd ,Sm ,Eu , and Gd )

NASA Astrophysics Data System (ADS)

Kováčik, Roman; Murthy, Sowmya Sathyanarayana; Quiroga, Carmen E.; Ederer, Claude; Franchini, Cesare

2016-02-01

We merge advanced ab initio schemes (standard density functional theory, hybrid functionals, and the G W approximation) with model Hamiltonian approaches (tight-binding and Heisenberg Hamiltonian) to study the evolution of the electronic, magnetic, and dielectric properties of the manganite family R MnO3 (R =La,Pr,Nd,Sm,Eu, and Gd) . The link between first principles and tight binding is established by downfolding the physically relevant subset of 3 d bands with eg character by means of maximally localized Wannier functions (MLWFs) using the VASP2WANNIER90 interface. The MLWFs are then used to construct a general tight-binding Hamiltonian written as a sum of the kinetic term, the Hund's rule coupling, the JT coupling, and the electron-electron interaction. The dispersion of the tight-binding (TB) eg bands at all levels are found to match closely the MLWFs. We provide a complete set of TB parameters which can serve as guidance for the interpretation of future studies based on many-body Hamiltonian approaches. In particular, we find that the Hund's rule coupling strength, the Jahn-Teller coupling strength, and the Hubbard interaction parameter U remain nearly constant for all the members of the R MnO3 series, whereas the nearest-neighbor hopping amplitudes show a monotonic attenuation as expected from the trend of the tolerance factor. Magnetic exchange interactions, computed by mapping a large set of hybrid functional total energies onto an Heisenberg Hamiltonian, clarify the origin of the A-type magnetic ordering observed in the early rare-earth manganite series as arising from a net negative out-of-plane interaction energy. The obtained exchange parameters are used to estimate the Néel temperature by means of Monte Carlo simulations. The resulting data capture well the monotonic decrease of the ordering temperature down the series from R =La to Gd, in agreement with experiments. This trend correlates well with the modulation of structural properties, in particular with the progressive reduction of the Mn-O-Mn bond angle which is associated with the quenching of the volume and the decrease of the tolerance factor due to the shrinkage of the ionic radii of R going from La to Gd.

Reconstruing U-Shaped Functions

ERIC Educational Resources Information Center

Werker, Janet F.; Hall, D. Geoffrey; Fais, Laurel

2004-01-01

U-shaped developmental functions, and their N-shaped cousins, have intrigued developmental psychologists for decades because they provide a compelling demonstration that development does not always entail a monotonic increase across age in a single underlying ability. Instead, the causes of development are much more complex. Indeed,…

Application of Lagrangian blending functions for grid generation around airplane geometries

NASA Technical Reports Server (NTRS)

Abolhassani, Jamshid S.; Sadrehaghighi, Ideen; Tiwari, Surendra N.

1990-01-01

A simple procedure was developed and applied for the grid generation around an airplane geometry. This approach is based on a transfinite interpolation with Lagrangian interpolation for the blending functions. A monotonic rational quadratic spline interpolation was employed for the grid distributions.

Fermionic Approach to Weighted Hurwitz Numbers and Topological Recursion

NASA Astrophysics Data System (ADS)

Alexandrov, A.; Chapuy, G.; Eynard, B.; Harnad, J.

2017-12-01

A fermionic representation is given for all the quantities entering in the generating function approach to weighted Hurwitz numbers and topological recursion. This includes: KP and 2D Toda {τ} -functions of hypergeometric type, which serve as generating functions for weighted single and double Hurwitz numbers; the Baker function, which is expanded in an adapted basis obtained by applying the same dressing transformation to all vacuum basis elements; the multipair correlators and the multicurrent correlators. Multiplicative recursion relations and a linear differential system are deduced for the adapted bases and their duals, and a Christoffel-Darboux type formula is derived for the pair correlator. The quantum and classical spectral curves linking this theory with the topological recursion program are derived, as well as the generalized cut-and-join equations. The results are detailed for four special cases: the simple single and double Hurwitz numbers, the weakly monotone case, corresponding to signed enumeration of coverings, the strongly monotone case, corresponding to Belyi curves and the simplest version of quantum weighted Hurwitz numbers.

Fermionic Approach to Weighted Hurwitz Numbers and Topological Recursion

NASA Astrophysics Data System (ADS)

Alexandrov, A.; Chapuy, G.; Eynard, B.; Harnad, J.

2018-06-01

A fermionic representation is given for all the quantities entering in the generating function approach to weighted Hurwitz numbers and topological recursion. This includes: KP and 2 D Toda {τ} -functions of hypergeometric type, which serve as generating functions for weighted single and double Hurwitz numbers; the Baker function, which is expanded in an adapted basis obtained by applying the same dressing transformation to all vacuum basis elements; the multipair correlators and the multicurrent correlators. Multiplicative recursion relations and a linear differential system are deduced for the adapted bases and their duals, and a Christoffel-Darboux type formula is derived for the pair correlator. The quantum and classical spectral curves linking this theory with the topological recursion program are derived, as well as the generalized cut-and-join equations. The results are detailed for four special cases: the simple single and double Hurwitz numbers, the weakly monotone case, corresponding to signed enumeration of coverings, the strongly monotone case, corresponding to Belyi curves and the simplest version of quantum weighted Hurwitz numbers.

Measuring the Evolution of Ontology Complexity: The Gene Ontology Case Study

PubMed Central

Dameron, Olivier; Bettembourg, Charles; Le Meur, Nolwenn

2013-01-01

Ontologies support automatic sharing, combination and analysis of life sciences data. They undergo regular curation and enrichment. We studied the impact of an ontology evolution on its structural complexity. As a case study we used the sixty monthly releases between January 2008 and December 2012 of the Gene Ontology and its three independent branches, i.e. biological processes (BP), cellular components (CC) and molecular functions (MF). For each case, we measured complexity by computing metrics related to the size, the nodes connectivity and the hierarchical structure. The number of classes and relations increased monotonously for each branch, with different growth rates. BP and CC had similar connectivity, superior to that of MF. Connectivity increased monotonously for BP, decreased for CC and remained stable for MF, with a marked increase for the three branches in November and December 2012. Hierarchy-related measures showed that CC and MF had similar proportions of leaves, average depths and average heights. BP had a lower proportion of leaves, and a higher average depth and average height. For BP and MF, the late 2012 increase of connectivity resulted in an increase of the average depth and average height and a decrease of the proportion of leaves, indicating that a major enrichment effort of the intermediate-level hierarchy occurred. The variation of the number of classes and relations in an ontology does not provide enough information about the evolution of its complexity. However, connectivity and hierarchy-related metrics revealed different patterns of values as well as of evolution for the three branches of the Gene Ontology. CC was similar to BP in terms of connectivity, and similar to MF in terms of hierarchy. Overall, BP complexity increased, CC was refined with the addition of leaves providing a finer level of annotations but decreasing slightly its complexity, and MF complexity remained stable. PMID:24146805

Human impacts on regional avian diversity and abundance

Treesearch

Christopher A. Lepczyk; Curtis H. Flather; Volker C. Radeloff; Anna M. Pidgeon; Roger B. Hammer; Jianguo Liu

2008-01-01

Patterns of association between humans and biodiversity typically show positive, negative, or negative quadratic relationships and can be described by 3 hypotheses: biologically rich areas that support high human population densities co-occur with areas of high biodiversity (productivity); biodiversity decreases monotonically with increasing human activities (ecosystem...

Aggregation Pattern Transitions by Slightly Varying the Attractive/Repulsive Function

PubMed Central

Cheng, Zhao; Zhang, Hai-Tao; Chen, Michael Z. Q.; Zhou, Tao; Valeyev, Najl V.

2011-01-01

Among collective behaviors of biological swarms and flocks, the attractive/repulsive (A/R) functional links between particles play an important role. By slightly changing the cutoff distance of the A/R function, a drastic transition between two distinct aggregation patterns is observed. More precisely, a large cutoff distance yields a liquid-like aggregation pattern where the particle density decreases monotonously from the inside to the outwards within each aggregated cluster. Conversely, a small cutoff distance produces a crystal-like aggregation pattern where the distance between each pair of neighboring particles remains constant. Significantly, there is an obvious spinodal in the variance curve of the inter-particle distances along the increasing cutoff distances, implying a legible transition pattern between the liquid-like and crystal-like aggregations. This work bridges the aggregation phenomena of physical particles and swarming of organisms in nature upon revealing some common mechanism behind them by slightly varying their inter-individual attractive/repulsive functions, and may find its potential engineering applications, for example, in the formation design of multi-robot systems and unmanned aerial vehicles (UAVs). PMID:21799776

Maxon and roton measurements in nanoconfined 4He

NASA Astrophysics Data System (ADS)

Bryan, M. S.; Sokol, P. E.

2018-05-01

We investigate the behavior of the collective excitations of adsorbed 4He in an ordered hexagonal mesopore, examining the crossover from a thin film to a confined fluid. Here, we present the inelastic scattering results as a function of filling at constant temperature. We find a monotonic transition of the maxon excitation as a function of filling. This has been interpreted as corresponding to an increasing density of the adsorbed helium, which approaches the bulk value as filling increases. The roton minimum exhibits a more complicated behavior that does not monotonically approach bulk values as filling increases. The full pore scattering resembles the bulk liquid accompanied by a layer mode. The maxon and roton scattering, taken together, at intermediate fillings does not correspond to a single bulk liquid dispersion at negative, low, or high pressure.

Cliophysics: Socio-Political Reliability Theory, Polity Duration and African Political (In)stabilities

PubMed Central

Cherif, Alhaji; Barley, Kamal

2010-01-01

Quantification of historical sociological processes have recently gained attention among theoreticians in the effort of providing a solid theoretical understanding of the behaviors and regularities present in socio-political dynamics. Here we present a reliability theory of polity processes with emphases on individual political dynamics of African countries. We found that the structural properties of polity failure rates successfully capture the risk of political vulnerability and instabilities in which , , , and of the countries with monotonically increasing, unimodal, U-shaped and monotonically decreasing polity failure rates, respectively, have high level of state fragility indices. The quasi-U-shape relationship between average polity duration and regime types corroborates historical precedents and explains the stability of the autocracies and democracies. PMID:21206911

Floating-Point Numerical Function Generators Using EVMDDs for Monotone Elementary Functions

DTIC Science & Technology

2009-01-01

Villa, R. K. Brayton , and A. L. Sangiovanni- Vincentelli, “Multi-valued decision diagrams: Theory and appli- cations,” Multiple-Valued Logic: An...Shmerko, and R. S. Stankovic, Decision Diagram Techniques for Micro- and Na- noelectronic Design, CRC Press, Taylor & Francis Group, 2006. Appendix

Applications of Lagrangian blending functions for grid generation around airplane geometries

NASA Technical Reports Server (NTRS)

Abolhassani, Jamshid S.; Sadrehaghighi, Ideen; Tiwari, Surendra N.; Smith, Robert E.

1990-01-01

A simple procedure has been developed and applied for the grid generation around an airplane geometry. This approach is based on a transfinite interpolation with Lagrangian interpolation for the blending functions. A monotonic rational quadratic spline interpolation has been employed for the grid distributions.

Decrease of Fisher information and the information geometry of evolution equations for quantum mechanical probability amplitudes.

PubMed

Cafaro, Carlo; Alsing, Paul M

2018-04-01

The relevance of the concept of Fisher information is increasing in both statistical physics and quantum computing. From a statistical mechanical standpoint, the application of Fisher information in the kinetic theory of gases is characterized by its decrease along the solutions of the Boltzmann equation for Maxwellian molecules in the two-dimensional case. From a quantum mechanical standpoint, the output state in Grover's quantum search algorithm follows a geodesic path obtained from the Fubini-Study metric on the manifold of Hilbert-space rays. Additionally, Grover's algorithm is specified by constant Fisher information. In this paper, we present an information geometric characterization of the oscillatory or monotonic behavior of statistically parametrized squared probability amplitudes originating from special functional forms of the Fisher information function: constant, exponential decay, and power-law decay. Furthermore, for each case, we compute both the computational speed and the availability loss of the corresponding physical processes by exploiting a convenient Riemannian geometrization of useful thermodynamical concepts. Finally, we briefly comment on the possibility of using the proposed methods of information geometry to help identify a suitable trade-off between speed and thermodynamic efficiency in quantum search algorithms.

Decrease of Fisher information and the information geometry of evolution equations for quantum mechanical probability amplitudes

NASA Astrophysics Data System (ADS)

Cafaro, Carlo; Alsing, Paul M.

2018-04-01

The relevance of the concept of Fisher information is increasing in both statistical physics and quantum computing. From a statistical mechanical standpoint, the application of Fisher information in the kinetic theory of gases is characterized by its decrease along the solutions of the Boltzmann equation for Maxwellian molecules in the two-dimensional case. From a quantum mechanical standpoint, the output state in Grover's quantum search algorithm follows a geodesic path obtained from the Fubini-Study metric on the manifold of Hilbert-space rays. Additionally, Grover's algorithm is specified by constant Fisher information. In this paper, we present an information geometric characterization of the oscillatory or monotonic behavior of statistically parametrized squared probability amplitudes originating from special functional forms of the Fisher information function: constant, exponential decay, and power-law decay. Furthermore, for each case, we compute both the computational speed and the availability loss of the corresponding physical processes by exploiting a convenient Riemannian geometrization of useful thermodynamical concepts. Finally, we briefly comment on the possibility of using the proposed methods of information geometry to help identify a suitable trade-off between speed and thermodynamic efficiency in quantum search algorithms.

Low temperature structural transitions in dipolar hard spheres: The influence on magnetic properties

NASA Astrophysics Data System (ADS)

Ivanov, A. O.; Kantorovich, S. S.; Rovigatti, L.; Tavares, J. M.; Sciortino, F.

2015-06-01

We investigate the structural chain-to-ring transition at low temperature in a gas of dipolar hard spheres (DHS). Due to the weakening of entropic contribution, ring formation becomes noticeable when the effective dipole-dipole magnetic interaction increases. It results in the redistribution of particles from usually observed flexible chains into flexible rings. The concentration (ρ) of DHS plays a crucial part in this transition: at a very low ρ only chains and rings are observed, whereas even a slight increase of the volume fraction leads to the formation of branched or defect structures. As a result, the fraction of DHS aggregated in defect-free rings turns out to be a non-monotonic function of ρ. The average ring size is found to be a slower increasing function of ρ when compared to that of chains. Both theory and computer simulations confirm the dramatic influence of the ring formation on the ρ-dependence of the initial magnetic susceptibility (χ) when the temperature decreases. The rings due to their zero total dipole moment are irresponsive to a weak magnetic field and drive to the strong decrease of the initial magnetic susceptibility.

Loudness Change in Response to Dynamic Acoustic Intensity

ERIC Educational Resources Information Center

Olsen, Kirk N.; Stevens, Catherine J.; Tardieu, Julien

2010-01-01

Three experiments investigate psychological, methodological, and domain-specific characteristics of loudness change in response to sounds that continuously increase in intensity (up-ramps), relative to sounds that decrease (down-ramps). Timbre (vowel, violin), layer (monotone, chord), and duration (1.8 s, 3.6 s) were manipulated in Experiment 1.…

Near-barrier Fusion Evaporation and Fission of 28Si+174Yb and 32S+170Er

NASA Astrophysics Data System (ADS)

Wang, Dongxi; Lin, Chengjian; Jia, Huiming; Ma, Nanru; Sun, Lijie; Xu, Xinxing; Yang, Lei; Yang, Feng; Zhang, Huanqiao; Bao, Pengfei

2017-11-01

Fusion evaporation residues and fission fragments have been measured, respectively, at energies around the Coulomb barrier for the 28Si+174Yb and 32S+170Er systems forming the same compound nucleus 202Po. The excitation function of fusion evaporation, fission as well as capture reactions were deduced. Coupled-channels analyses reveal that couplings to the deformations of targets and the two-phonon states of projectiles contribute much to the enhancement of capture cross sections at sub-barrier energies. The mass and total kinetic energy of fission fragments were deduced by the time-difference method assuming full momentum transfer in a two-body kinematics. The mass-energy and mass-angle distributions were obtained and no obvious quasi-fission components were observed in this bombarding energy range. Further, mass distributions of fission fragments were fitted to extract their widths. Results show that the mass widths decrease monotonically with decreasing energy, but might start to increase when Ec.m./VB < 0.95 for both systems.

Gamma-irradiation effect on a commercial composite anticorrosive pigment and acidity-to-alkalinity conversion

NASA Astrophysics Data System (ADS)

Song, Weiqiang; Niu, Kaihui; Wu, Longchao

2016-05-01

A commercial composite anticorrosive pigment based on aluminum dihydrogen tripolyphosphate was studied after exposure to gamma irradiation (Co60, 0, 20, 50, 100 and 150 kGy) using FTIR, XRD, TGA and acid-base titration technologies. Although the FTIR spectra showed that the effect of the irradiation on functional groups in the pigments was not obvious, the decrease in the crystal lattice parameters of the irradiated pigments was observed in the XRD spectra compared to the non-irradiated sample. But the extent of the lattice parameter decrease monotonically with the increase of absorbed dose from 20 to 150 kGy, which was attributed to the decomposition of water and the simultaneous occurrence of lattice damage when the pigments were exposed to gamma rays. Of particular significance was the displayed basicity of the aqueous solutions of the irradiated pigments compared to the acidity of the solution of the non-irradiated pigment, which was attributed to the decomposition of P-OH groups (combined water).

Gel phase in hydrated calcium dipicolinate

NASA Astrophysics Data System (ADS)

Rajak, Pankaj; Mishra, Ankit; Sheng, Chunyang; Tiwari, Subodh; Krishnamoorthy, Aravind; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

2017-11-01

The mineralization of dipicolinic acid (DPA) molecules in bacterial spore cores with Ca2+ ions to form Ca-DPA is critical to the wet-heat resistance of spores. This resistance to "wet-heat" also depends on the physical properties of water and DPA in the hydrated Ca-DPA-rich protoplasm. Using reactive molecular dynamics simulations, we have determined the phase diagram of hydrated Ca-DPA as a function of temperature and water concentration, which shows the existence of a gel phase along with distinct solid-gel and gel-liquid phase transitions. Simulations reveal monotonically decreasing solid-gel-liquid transition temperatures with increasing hydration, which explains the experimental trend of wet-heat resistance of bacterial spores. Our observation of different phases of water also reconciles previous conflicting experimental findings on the state of water in bacterial spores. Further comparison with an unmineralized hydrated DPA system allows us to quantify the importance of Ca mineralization in decreasing diffusivity and increasing the heat resistance of the spore.

Random sequential adsorption of straight rigid rods on a simple cubic lattice

NASA Astrophysics Data System (ADS)

García, G. D.; Sanchez-Varretti, F. O.; Centres, P. M.; Ramirez-Pastor, A. J.

2015-10-01

Random sequential adsorption of straight rigid rods of length k (k-mers) on a simple cubic lattice has been studied by numerical simulations and finite-size scaling analysis. The k-mers were irreversibly and isotropically deposited into the lattice. The calculations were performed by using a new theoretical scheme, whose accuracy was verified by comparison with rigorous analytical data. The results, obtained for k ranging from 2 to 64, revealed that (i) the jamming coverage for dimers (k = 2) is θj = 0.918388(16) . Our result corrects the previously reported value of θj = 0.799(2) (Tarasevich and Cherkasova, 2007); (ii) θj exhibits a decreasing function when it is plotted in terms of the k-mer size, being θj(∞) = 0.4045(19) the value of the limit coverage for large k's; and (iii) the ratio between percolation threshold and jamming coverage shows a non-universal behavior, monotonically decreasing to zero with increasing k.

Conduction in Carbon Nanotubes Through Metastable Resonant States

NASA Astrophysics Data System (ADS)

Zhang, Zhengfan; Chandrasekhar, Venkat; Dikin, Dmitriy A.; Ruoff, Rodney S.

2004-03-01

We have made transport measurements on individual multi-walled carbon nanotubes [1]. The measurements show that the presence or movement of impurities or defects in the carbon nanotube can radically change its low temperature transport characteristics. The low temperature conductance can either decrease monotonically with decreasing temperature, or show a sudden increase at very low temperatures, sometimes in the same sample. This unusual behavior of the temperature dependence of the conductance is correlated with large variations in the differential conductance as a function of the dc voltage across the wire. The effect is well described as arising from quantum interference of conduction channels corresponding to direct transmission through the nanotube and resonant transmission through a discrete electron state, the so-called Fano resonance. We thank the group of R. P. H. Chang for providing us the nanotubes used in these experiments. Funding for this work was provided by a NASA/MSFC Phase II SBIR, Contract No. NAS8-02102, through a subcontract from Lytec, LLC. [1] Z. Zhang et al., cond-mat/0311360.

Cryogenic temperature dependence of the voltage transfer characteristics of CMOS inverters

NASA Astrophysics Data System (ADS)

Deen, M. J.

1988-08-01

The voltage transfer characteristics of CMOS inverters have been studied in detail as a function of temperature between 77 and 300 K and supply voltages between 2 and 20 V. The logic levels, maximum gain, unity gain points, noise margins and other parameters, such as ( VH - VL), all showed a marked improvement as the temperature was lowered. In particular, for one inverter with a supply of 5 V, the maximum gain increased from 57 to 105, ( VIH - VIL) decreased from 0.50 to 0.28 V and ( VH - VL) increased from 4.46 to 4.75 V on decreasing the temperature from 300 to 77 K. For all the inverters, these and other parameters showed a smooth monotonic improvement as the temperature was lowered. These and the other results obtained can be qualitatively explained as due to an increase in the absolute values in the threshold voltages of the PMOS and NMOS transistors and to an increase in the carrier mobility as the temperature was lowered.

Complexity of the AdS soliton

NASA Astrophysics Data System (ADS)

Reynolds, Alan P.; Ross, Simon F.

2018-05-01

We consider the holographic complexity conjectures in the context of the AdS soliton, which is the holographic dual of the ground state of a field theory on a torus with antiperiodic boundary conditions for fermions on one cycle. The complexity is a non-trivial function of the size of the circle with antiperiodic boundary conditions, which sets an IR scale in the dual geometry. We find qualitative differences between the calculations of complexity from spatial volume and action (CV and CA). In the CV calculation, the complexity for antiperiodic boundary conditions is smaller than for periodic, and decreases monotonically with increasing IR scale. In the CA calculation, the complexity for antiperiodic boundary conditions is larger than for periodic, and initially increases with increasing IR scale, eventually decreasing to zero as the IR scale becomes of order the UV cutoff. We compare these results to a simple calculation for free fermions on a lattice, where we find the complexity for antiperiodic boundary conditions is larger than for periodic.

Study of stiffness and bearing capacity degradation of reinforced concrete beams under constant-amplitude fatigue

PubMed Central

Zhou, Jianting; Yan, Lei

2018-01-01

For a reinforced concrete beam subjected to fatigue loads, the structural stiffness and bearing capacity will gradually undergo irreversible degeneration, leading to damage. Moreover, there is an inherent relationship between the stiffness and bearing capacity degradation and fatigue damage. In this study, a series of fatigue tests are performed to examine the degradation law of the stiffness and bearing capacity. The results pertaining to the stiffness show that the stiffness degradation of a reinforced concrete beam exhibits a very clear monotonic decreasing "S" curve, i.e., the stiffness of the beam decreases significantly at the start of the fatigue loading, it undergoes a linear decline phase in the middle for a long loading period, and before the failure, the bearing capacity decreases drastically again. The relationship between the residual stiffness and residual bearing capacity is determined based on the assumption that the residual stiffness and residual bearing capacity depend on the same damage state, and then, the bearing capacity degradation model of the reinforced concrete beam is established based on the fatigue stiffness. Through the established model and under the premise of the known residual stiffness degradation law, the degradation law of the bearing capacity is determined by using at least one residual bearing capacity test data, for which the parameters of the stiffness degradation function are considered as material constants. The results of the bearing capacity show that the bearing capacity degradation of the reinforced concrete beam also exhibits a very clear monotonic decreasing "S" curve, which is consistent with the stiffness degradation process and in good agreement with the experiment. In this study, the stiffness and bearing capacity degradation expressions are used to quantitatively describe their occurrence in reinforced concrete beams. In particular, the expression of the bearing capacity degradation can mitigate numerous destructive tests and save cost. The stiffness and bearing capacity degradation expressions for a reinforced concrete beam can be used to predict the deformation and bearing capacity of a structure during the service process and determine the structural fatigue damage and degree of degradation. PMID:29522572

Study of stiffness and bearing capacity degradation of reinforced concrete beams under constant-amplitude fatigue.

PubMed

Liu, Fangping; Zhou, Jianting; Yan, Lei

2018-01-01

For a reinforced concrete beam subjected to fatigue loads, the structural stiffness and bearing capacity will gradually undergo irreversible degeneration, leading to damage. Moreover, there is an inherent relationship between the stiffness and bearing capacity degradation and fatigue damage. In this study, a series of fatigue tests are performed to examine the degradation law of the stiffness and bearing capacity. The results pertaining to the stiffness show that the stiffness degradation of a reinforced concrete beam exhibits a very clear monotonic decreasing "S" curve, i.e., the stiffness of the beam decreases significantly at the start of the fatigue loading, it undergoes a linear decline phase in the middle for a long loading period, and before the failure, the bearing capacity decreases drastically again. The relationship between the residual stiffness and residual bearing capacity is determined based on the assumption that the residual stiffness and residual bearing capacity depend on the same damage state, and then, the bearing capacity degradation model of the reinforced concrete beam is established based on the fatigue stiffness. Through the established model and under the premise of the known residual stiffness degradation law, the degradation law of the bearing capacity is determined by using at least one residual bearing capacity test data, for which the parameters of the stiffness degradation function are considered as material constants. The results of the bearing capacity show that the bearing capacity degradation of the reinforced concrete beam also exhibits a very clear monotonic decreasing "S" curve, which is consistent with the stiffness degradation process and in good agreement with the experiment. In this study, the stiffness and bearing capacity degradation expressions are used to quantitatively describe their occurrence in reinforced concrete beams. In particular, the expression of the bearing capacity degradation can mitigate numerous destructive tests and save cost. The stiffness and bearing capacity degradation expressions for a reinforced concrete beam can be used to predict the deformation and bearing capacity of a structure during the service process and determine the structural fatigue damage and degree of degradation.

Influence of age, speed and duration of monotonous driving task in traffic on the driver's useful visual field.

PubMed

Rogé, Joceline; Pébayle, Thierry; Lambilliotte, Elina; Spitzenstetter, Florence; Giselbrecht, Danièle; Muzet, Alain

2004-10-01

Recent research has shown that the useful visual field deteriorates in simulated car driving when the latter can induce a decrease in the level of activation. The first aim of this study was to verify if the same phenomenon occurs when driving is performed in a simulated road traffic situation. The second aim was to discover if this field also deteriorates as a function of the driver's age and of the vehicle's speed. Nine young drivers (from 22 to 34 years) and nine older drivers (from 46 to 59 years) followed a vehicle in road traffic during two two-hour sessions. The car-following task involved driving at 90 km.h(-1) (speed limit on road in France) in one session and at 130 km.h(-1) (speed limit on motorway in France) in the other session. While following the vehicle, the driver had to detect the changes in colour of a luminous signal located in the central part of his/her visual field and a visual signal that appeared at different eccentricities on the rear lights of the vehicles in the traffic. The analysis of the data indicates that the useful visual field deteriorates with the prolongation of the monotonous simulated driving task, with the driver's age and with the vehicle's speed. The results are discussed in terms of general interference and tunnel vision.

Six months exposure to a real life mixture of 13 chemicals' below individual NOAELs induced non monotonic sex-dependent biochemical and redox status changes in rats.

PubMed

Docea, Anca Oana; Gofita, Eliza; Goumenou, Marina; Calina, Daniela; Rogoveanu, Otilia; Varut, Marius; Olaru, Cristian; Kerasioti, Efthalia; Fountoucidou, Polyxeni; Taitzoglou, Ioannis; Zlatian, Ovidiu; Rakitskii, Valerii N; Hernandez, Antonio F; Kouretas, Dimitrios; Tsatsakis, Aristidis

2018-05-01

This study assessed the potential adverse health effects of long-term low-dose exposure to chemical mixtures simulating complex real-life human exposures. Four groups of Sprague Dawley rats were administered mixtures containing carbaryl, dimethoate, glyphosate, methomyl, methyl parathion, triadimefon, aspartame, sodium benzoate, calcium disodium ethylene diamine tetra-acetate, ethylparaben, butylparaben, bisphenol A, and acacia gum at doses of 0, 0.25, 1 or 5 times the respective Toxicological Reference Values (TRV): acceptable daily intake (ADI) or tolerable daily intake (TDI) in a 24 weeks toxicity study. Body weight gain, feed and water consumption were evaluated weekly. At 24 weeks blood was collected and biochemistry parameters and redox status markers were assessed. Adverse effects were observed on body weight gain and in hepatotoxic parameters such as the total bilirubin, alanine aminotransferase (ALT) and alkaline phosphatase (ALP), especially in low dose and affecting mainly male rats. The low dose group showed increased catalase activity both in females and males, whereas the high dose group exhibited decreased protein carbonyl and total antioxidant capacity (TAC) levels in both sex groups. Non-monotonic effects and adaptive responses on liver function tests and redox status, leading to non-linear dose-responses curves, are probably produced by modulation of different mechanisms. Copyright © 2018. Published by Elsevier Ltd.

EOS Interpolation and Thermodynamic Consistency

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

Gammel, J. Tinka

2015-11-16

As discussed in LA-UR-08-05451, the current interpolator used by Grizzly, OpenSesame, EOSPAC, and similar routines is the rational function interpolator from Kerley. While the rational function interpolator is well-suited for interpolation on sparse grids with logarithmic spacing and it preserves monotonicity in 1-d, it has some known problems.

Optimal voltage stimulation parameters for network-mediated responses in wild type and rd10 mouse retinal ganglion cells

NASA Astrophysics Data System (ADS)

Jalligampala, Archana; Sekhar, Sudarshan; Zrenner, Eberhart; Rathbun, Daniel L.

2017-04-01

To further improve the quality of visual percepts elicited by microelectronic retinal prosthetics, substantial efforts have been made to understand how retinal neurons respond to electrical stimulation. It is generally assumed that a sufficiently strong stimulus will recruit most retinal neurons. However, recent evidence has shown that the responses of some retinal neurons decrease with excessively strong stimuli (a non-monotonic response function). Therefore, it is necessary to identify stimuli that can be used to activate the majority of retinal neurons even when such non-monotonic cells are part of the neuronal population. Taking these non-monotonic responses into consideration, we establish the optimal voltage stimulation parameters (amplitude, duration, and polarity) for epiretinal stimulation of network-mediated (indirect) ganglion cell responses. We recorded responses from 3958 mouse retinal ganglion cells (RGCs) in both healthy (wild type, WT) and a degenerating (rd10) mouse model of retinitis pigmentosa—using flat-mounted retina on a microelectrode array. Rectangular monophasic voltage-controlled pulses were presented with varying voltage, duration, and polarity. We found that in 4-5 weeks old rd10 mice the RGC thresholds were comparable to those of WT. There was a marked response variability among mouse RGCs. To account for this variability, we interpolated the percentage of RGCs activated at each point in the voltage-polarity-duration stimulus space, thus identifying the optimal voltage-controlled pulse (-2.4 V, 0.88 ms). The identified optimal voltage pulse can activate at least 65% of potentially responsive RGCs in both mouse strains. Furthermore, this pulse is well within the range of stimuli demonstrated to be safe and effective for retinal implant patients. Such optimized stimuli and the underlying method used to identify them support a high yield of responsive RGCs and will serve as an effective guideline for future in vitro investigations of retinal electrostimulation by establishing standard stimuli for each unique experimental condition.

Electronic Structure of Two-Dimensional Hydrocarbon Networks of sp2 and sp3 C Atoms

NASA Astrophysics Data System (ADS)

Fujii, Yasumaru; Maruyama, Mina; Wakabayashi, Katsunori; Nakada, Kyoko; Okada, Susumu

2018-03-01

Based on density functional theory with the generalized gradient approximation, we have investigated the geometric and electronic structures of two-dimensional hexagonal covalent networks consisting of oligoacenes and fourfold coordinated hydrocarbon atoms, which are alternately arranged in a hexagonal manner. All networks were semiconductors with a finite energy gap at the Γ point, which monotonically decreased with the increase of the oligoacene length. As a result of a Kagome network of oligoacene connected through sp3 C atoms, the networks possess peculiar electron states in their valence and conduction bands, which consist of a flat dispersion band and a Dirac cone. The total energy of the networks depends on the oligoacene length and has a minimum for the network comprising naphthalene.

Hydrogen content and mechanical stress in glow discharge amorphous silicon

NASA Astrophysics Data System (ADS)

Paduschek, P.; Eichinger, P.; Kristen, G.; Mitlehner, H.

1982-08-01

The hydrogen content of plasma deposited amorphous silicon thin films on silicon has been determined as a function of annealing parameters (200-700°C, 12 h) using the proton-proton scattering method. It is shown that hydrogen is released with an activation energy of 1.3 eV. Different deposition temperatures are compared with respect to the hydrogen evolution. The mechanical stress of the layers on silicon substrates has been measured by interferometric techniques for each annealing step. As the hydrogen content decreases monotonically with rising annealing temperature the mechanical stress converts from compressive to tensile. While only a weak correlation exists between the total hydrogen content and the mechanical stress, the bound hydrogen as determined by IR absorption displays a linear relation with the measured mechanical stress.

Radiation-induced polymerization of glass forming systems. VI. Polymerization rate at higher conversion in binary systems

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

Kaetsu, I.; Ito, A.; Hayashi, K.

1973-08-01

The effect of temperature and composition on the inflection point in the time-conversion curve and the saturated conversion was investigated in the gamma -radio-induced radical polymerization of binary systems consisting of a glass- forming monomer and a solvent. In the polymerization of completely homogeneous systems such as glycidyl methacrylate (GMA) -triacetin and hydroxyethyl methacrylate (HEMA) --propylene glycol systems, the time-conversion curve has an inflection point at polymerization temperatures between T/sub vm/(T/sub v/ of monomer system) and T/sub vp/ (T/sub v/ of polymer system). Such conversions at the inflection point changed monotonically between 0 and 100% in this temperature range. T/submore » v/ was found to be 30 to 50 deg C higher than T/sub g/ (glass transition temperature) and a monotonic function of composition (monomer -- polymer -- solvent). The acceleration effect continued to 100% conversion above T/sub vp/, and no acceleration effect was observed below T/sub vm/. The saturated conversion in homogeneous systems changed monotonically between 0 and 100% for polymerization temperatures between T/sub gm/ (T/sub g/ of monomer system) and T/sub gp/(T of polymer system). T/sub g/ was also a monotonic function of composition. No saturation in conversion was observed above T/sub gp/ , and no polymerization occurred below T/sub gm/. In the polymerization of completely heterogeneous systems such as HEMA-dioctyl phthalate, no acceleration effect was observed at any temperature and composition. The saturated conversion was 100% sbove T/sub g/ of pure HEMA, and no polymerization occurred below this temperature in this system. (auth)« less

On equivalent characterizations of convexity of functions

NASA Astrophysics Data System (ADS)

Gkioulekas, Eleftherios

2013-04-01

A detailed development of the theory of convex functions, not often found in complete form in most textbooks, is given. We adopt the strict secant line definition as the definitive definition of convexity. We then show that for differentiable functions, this definition becomes logically equivalent with the first derivative monotonicity definition and the tangent line definition. Consequently, for differentiable functions, all three characterizations are logically equivalent.

Cardiovascular hemodynamic effects of Red Bull® Energy Drink during prolonged, simulated, monotonous driving.

PubMed

Yamakoshi, Takehiro; Matsumura, Kenta; Hanaki, Shota; Rolfe, Peter

2013-12-01

The purpose of this study was to investigate the cardiovascular hemodynamic effects of Red Bull® Energy Drink during prolonged, simulated, monotonous driving. This was a double-blind, within-subjects-design, crossover study. Twelve healthy volunteers (21.7 ± 0.8 years old) experienced each of three conditions at various times: 1) consumption of Red Bull® Energy Drink; 2) consumption of placebo-controlled drink; and 3) no test drink. All subjects undertook 90-min periods of simulated monotonous driving, during which physiological measurements were made. The variables recorded were cardiovascular indices, i.e., mean blood pressure (MBP), cardiac output (CO), electrocardiogram RR interval (RR), total peripheral-vascular resistance (TPR: = MBP/CO), and normalized pulse volume (NPV). Additional parameters were the standard deviation of lateral position, i.e., the weaving of the car, and subjective rating of sleepiness. CO, RR, and TPR during the monotonous task were significantly different in those consuming the energy drink as compared with those receiving the placebo and as compared with no drink values. The energy drink elicited a cardiac-dominant reaction pattern, while the other conditions demonstrated the vascular-dominant reaction pattern typically observed in monotonous driving tasks. The observed differences indicate the cardiovascular system being more aroused with the energy drink. The effects of Red Bull® Energy Drink were reflected in cardiovascular hemodynamic phenomena especially to the heart function, and we conclude that consumption of this drink before long-distance driving in non-sleepy drivers could facilitate more physiologically active, and possibly safer, driving.

Response Errors Explain the Failure of Independent-Channels Models of Perception of Temporal Order

PubMed Central

García-Pérez, Miguel A.; Alcalá-Quintana, Rocío

2012-01-01

Independent-channels models of perception of temporal order (also referred to as threshold models or perceptual latency models) have been ruled out because two formal properties of these models (monotonicity and parallelism) are not borne out by data from ternary tasks in which observers must judge whether stimulus A was presented before, after, or simultaneously with stimulus B. These models generally assume that observed responses are authentic indicators of unobservable judgments, but blinks, lapses of attention, or errors in pressing the response keys (maybe, but not only, motivated by time pressure when reaction times are being recorded) may make observers misreport their judgments or simply guess a response. We present an extension of independent-channels models that considers response errors and we show that the model produces psychometric functions that do not satisfy monotonicity and parallelism. The model is illustrated by fitting it to data from a published study in which the ternary task was used. The fitted functions describe very accurately the absence of monotonicity and parallelism shown by the data. These characteristics of empirical data are thus consistent with independent-channels models when response errors are taken into consideration. The implications of these results for the analysis and interpretation of temporal order judgment data are discussed. PMID:22493586

Time-dependent density functional theory for the charging kinetics of electric double layer containing room-temperature ionic liquids

DOE PAGES

Lian, Cheng; Univ. of California, Riverside, CA; Zhao, Shuangliang; ...

2016-11-29

Understanding the charging kinetics of electric double layers is of fundamental importance for the design and development of novel electrochemical devices such as supercapacitors and field-effect transistors. In this paper, we study the dynamic behavior of room-temperature ionic liquids using a classical time-dependent density functional theory that accounts for the molecular excluded volume effects, the electrostatic correlations, and the dispersion forces. While the conventional models predict a monotonic increase of the surface charge with time upon application of an electrode voltage, our results show that dispersion between ions results in a non-monotonic increase of the surface charge with the durationmore » of charging. Finally and furthermore, we investigate the effects of van der Waals attraction between electrode/ionic-liquid interactions on the charging processes.« less

Resistivity and resistivity fluctuations of thin-film platinum-aluminum oxide granular metal-insulator composites

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

Mantese, J.V.

1986-01-01

Thin film metal-insulator composites were used to study how the resistivity and fluctuations in the resistivity were altered by changes in conduction mechanism so as to understand the source of the fluctuations and to better understand the conduction processes themselves. Metal-insulator composites were prepared by co-evaporation of platinum and aluminum oxide in a high vacuum system to create a series of films which had a range of metal volume fill fractions, p, from 23 to 100%. The samples were patterned using standard photolithographic techniques to form sample geometries of typical dimensions, length approx.40 ..mu..m, width approx.2 ..mu..m, and thickness approx.1500more » A. The resistivity rho, and power spectral density of the resistivity fluctuations, S/sub rho/(f), were measured as a function of p and temperature, T. Rho(p,T) was found to be a rapidly increasing function of decreasing p, rising monotonically by more than 7 orders of magnitude as p was decreased from 100% to 23%. For p greater than or equal to 59% the resistivity decreased linearly with decreasing temperature until limited by impurity scattering. The resistivities for the low metal fill fraction materials (P greater than or equal to 50%) increased as the temperature was reduced as expected of thermally assisted tunneling conduction in metal-insulator composites. The transition from metallic conduction to thermally assisted tunneling occurred at a critical value, p/sub c/, between 59% and 50% Pt.« less

Marginal Consistency: Upper-Bounding Partition Functions over Commutative Semirings.

PubMed

Werner, Tomás

2015-07-01

Many inference tasks in pattern recognition and artificial intelligence lead to partition functions in which addition and multiplication are abstract binary operations forming a commutative semiring. By generalizing max-sum diffusion (one of convergent message passing algorithms for approximate MAP inference in graphical models), we propose an iterative algorithm to upper bound such partition functions over commutative semirings. The iteration of the algorithm is remarkably simple: change any two factors of the partition function such that their product remains the same and their overlapping marginals become equal. In many commutative semirings, repeating this iteration for different pairs of factors converges to a fixed point when the overlapping marginals of every pair of factors coincide. We call this state marginal consistency. During that, an upper bound on the partition function monotonically decreases. This abstract algorithm unifies several existing algorithms, including max-sum diffusion and basic constraint propagation (or local consistency) algorithms in constraint programming. We further construct a hierarchy of marginal consistencies of increasingly higher levels and show than any such level can be enforced by adding identity factors of higher arity (order). Finally, we discuss instances of the framework for several semirings, including the distributive lattice and the max-sum and sum-product semirings.

On convergence of differential evolution over a class of continuous functions with unique global optimum.

PubMed

Ghosh, Sayan; Das, Swagatam; Vasilakos, Athanasios V; Suresh, Kaushik

2012-02-01

Differential evolution (DE) is arguably one of the most powerful stochastic real-parameter optimization algorithms of current interest. Since its inception in the mid 1990s, DE has been finding many successful applications in real-world optimization problems from diverse domains of science and engineering. This paper takes a first significant step toward the convergence analysis of a canonical DE (DE/rand/1/bin) algorithm. It first deduces a time-recursive relationship for the probability density function (PDF) of the trial solutions, taking into consideration the DE-type mutation, crossover, and selection mechanisms. Then, by applying the concepts of Lyapunov stability theorems, it shows that as time approaches infinity, the PDF of the trial solutions concentrates narrowly around the global optimum of the objective function, assuming the shape of a Dirac delta distribution. Asymptotic convergence behavior of the population PDF is established by constructing a Lyapunov functional based on the PDF and showing that it monotonically decreases with time. The analysis is applicable to a class of continuous and real-valued objective functions that possesses a unique global optimum (but may have multiple local optima). Theoretical results have been substantiated with relevant computer simulations.

Denjoy minimal sets and Birkhoff periodic orbits for non-exact monotone twist maps

NASA Astrophysics Data System (ADS)

Qin, Wen-Xin; Wang, Ya-Nan

2018-06-01

A non-exact monotone twist map φbarF is a composition of an exact monotone twist map φ bar with a generating function H and a vertical translation VF with VF ((x , y)) = (x , y - F). We show in this paper that for each ω ∈ R, there exists a critical value Fd (ω) ≥ 0 depending on H and ω such that for 0 ≤ F ≤Fd (ω), the non-exact twist map φbarF has an invariant Denjoy minimal set with irrational rotation number ω lying on a Lipschitz graph, or Birkhoff (p , q)-periodic orbits for rational ω = p / q. Like the Aubry-Mather theory, we also construct heteroclinic orbits connecting Birkhoff periodic orbits, and show that quasi-periodic orbits in these Denjoy minimal sets can be approximated by periodic orbits. In particular, we demonstrate that at the critical value F =Fd (ω), the Denjoy minimal set is not uniformly hyperbolic and can be approximated by smooth curves.

Reduced-order model for inertial locomotion of a slender swimmer

NASA Astrophysics Data System (ADS)

Mahalinkam, Raksha; Gong, Felicity; Khair, Aditya S.

2018-04-01

The inertial locomotion of an elongated model swimmer in a Newtonian fluid is quantified, wherein self-propulsion is achieved via steady tangential surface treadmilling. The swimmer has a length 2 l and a circular cross section of longitudinal profile a R (z ) , where a is the characteristic width of the cross section, R (z ) is a dimensionless shape function, and z is a dimensionless coordinate, normalized by l , along the centerline of the body. It is assumed that the swimmer is slender, ɛ =a /l ≪1 . Hence, we utilize slender-body theory to analyze the Navier-Stokes equations that describe the flow around the swimmer. Therefrom, we compute an asymptotic approximation to the swimming speed, U , as U /us=1 -β [V (Re ) -1/2 ∫-11z lnR (z ) d z ] /ln(1 /ɛ ) +O [1 /ln2(1 /ɛ ) ], where us is the characteristic speed of the surface treadmilling, Re is the Reynolds number based on the body length, and β is a dimensionless parameter that differentiates between "pusher" (propelled from the rear, β <0 ) and "puller" (propelled from the front, β >0 ) -type swimmers. The function V (Re ) increases monotonically with increasing Re ; hence, fluid inertia causes an increase (decrease) in the swimming speed of a pusher (puller). Next, we demonstrate that the power expenditure of the swimmer increases monotonically with increasing Re . Further, the power expenditures of a puller and pusher with the same value of |β | are equal. Therefore, pushers are superior in inertial locomotion as compared to pullers, in that they achieve a faster swimming speed for the same power expended. Finally, it is demonstrated that the flow structure predicted from our reduced-order model is consistent with that from direct numerical simulation of swimmers at intermediate Re .

Excess chemical potential of small solutes across water--membrane and water--hexane interfaces

NASA Technical Reports Server (NTRS)

Pohorille, A.; Wilson, M. A.

1996-01-01

The excess chemical potentials of five small, structurally related solutes, CH4, CH3F, CH2F2, CHF3, and CF4, across the water-glycerol 1-monooleate bilayer and water-hexane interfaces were calculated at 300, 310, and 340 K using the particle insertion method. The excess chemical potentials of nonpolar molecules (CH4 and CF4) decrease monotonically or nearly monotonically from water to a nonpolar phase. In contrast, for molecules that possess permanent dipole moments (CH3F, CH2F, and CHF3), the excess chemical potentials exhibit an interfacial minimum that arises from superposition of two monotonically and oppositely changing contributions: electrostatic and nonelectrostatic. The nonelectrostatic term, dominated by the reversible work of creating a cavity that accommodates the solute, decreases, whereas the electrostatic term increases across the interface from water to the membrane interior. In water, the dependence of this term on the dipole moment is accurately described by second order perturbation theory. To achieve the same accuracy at the interface, third order terms must also be included. In the interfacial region, the molecular structure of the solvent influences both the excess chemical potential and solute orientations. The excess chemical potential across the interface increases with temperature, but this effect is rather small. Our analysis indicates that a broad range of small, moderately polar molecules should be surface active at the water-membrane and water-oil interfaces. The biological and medical significance of this result, especially in relation to the mechanism of anesthetic action, is discussed.

Driver state examination--Treading new paths.

PubMed

Wascher, Edmund; Getzmann, Stephan; Karthaus, Melanie

2016-06-01

A large proportion of crashes in road driving can be attributed to driver fatigue. Several types of fatigue are discussed, comprising sleep-related fatigue, active task-related fatigue (as a consequence of workload in demanding driving situations) as well as passive task-related fatigue (as related to monotonous driving situations). The present study investigated actual states of fatigue in a monotonous driving situation, using EEG measures and a long-lasting driving simulation experiment, in which drivers had to keep the vehicle on track by compensating crosswind of different strength. Performance data and electrophysiological correlates of mental fatigue (EEG Alpha and Theta power, Inter Trial Coherence (ITC), and auditory event-related potentials to short sound stimuli) were analyzed. Driving errors and driving lane variability increased with time on task and with increasing crosswind. The posterior Alpha and Theta power also increased with time on task, but decreased with stronger crosswind. The P3a to sound stimuli decreased with time on task when the crosswind was weak, but remained stable when the crosswind was strong. The analysis of ITC revealed less frontal Alpha and Theta band synchronization with time on task, but no effect of crosswind. The results suggest that Alpha power in monotonous driving situations reflects boredom or attentional withdrawal due to monotony rather than the decline of processing abilities as a consequence of high mental effort. A more valid indicator of declining mental resources with increasing time on task seems to be provided by brain oscillatory synchronization measures and event-related activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cooperation enhanced by habitat destruction in Prisoner's Dilemma Games

NASA Astrophysics Data System (ADS)

Yang, Xiqing; Wang, Wanxiong; Zhang, Feng; Qiao, Hongqiang

2017-11-01

The emergence and maintenance of cooperation is a fundamental problem within groups of selfish individuals, whereby we introduce a model of replicator equations based on the Prisoner's Dilemma game. In the present work, the effect of habitat destruction on the evolution of cooperation will be taken into account. Our results show that cooperators can receive the biggest boost for a moderate value of habitat destruction, and more serious habitat destruction will lead to lower levels of cooperation until zero. Moreover, we also reach the conclusion that the cooperation level decreases monotonously with the increasing of the ratio of cooperative cost to benefit but increases monotonously with the increasing of the encounter probability. Our findings can help to further understand the evolution of cooperation under the harsh external environment.

Colloidal nanocrystals and method of making

DOEpatents

Kahen, Keith

2015-10-06

A tight confinement nanocrystal comprises a homogeneous center region having a first composition and a smoothly varying region having a second composition wherein a confining potential barrier monotonically increases and then monotonically decreases as the smoothly varying region extends from the surface of the homogeneous center region to an outer surface of the nanocrystal. A method of producing the nanocrystal comprises forming a first solution by combining a solvent and at most two nanocrystal precursors; heating the first solution to a nucleation temperature; adding to the first solution, a second solution having a solvent, at least one additional and different precursor to form the homogeneous center region and at most an initial portion of the smoothly varying region; and lowering the solution temperature to a growth temperature to complete growth of the smoothly varying region.

Solution of monotone complementarity and general convex programming problems using a modified potential reduction interior point method

DOE PAGES

Huang, Kuo -Ling; Mehrotra, Sanjay

2016-11-08

We present a homogeneous algorithm equipped with a modified potential function for the monotone complementarity problem. We show that this potential function is reduced by at least a constant amount if a scaled Lipschitz condition (SLC) is satisfied. A practical algorithm based on this potential function is implemented in a software package named iOptimize. The implementation in iOptimize maintains global linear and polynomial time convergence properties, while achieving practical performance. It either successfully solves the problem, or concludes that the SLC is not satisfied. When compared with the mature software package MOSEK (barrier solver version 6.0.0.106), iOptimize solves convex quadraticmore » programming problems, convex quadratically constrained quadratic programming problems, and general convex programming problems in fewer iterations. Moreover, several problems for which MOSEK fails are solved to optimality. In addition, we also find that iOptimize detects infeasibility more reliably than the general nonlinear solvers Ipopt (version 3.9.2) and Knitro (version 8.0).« less

Thermodynamic factors in partitioning and rejection of organic compounds by polyamide composite membranes.

PubMed

Ben-David, Adi; Oren, Yoram; Freger, Viatcheslav

2006-11-15

The paper analyzes the mechanism of partitioning and rejection of organic solutes by polyamide membranes for reverse osmosis and nanofiltration. The partitioning of homologous series of alcohols and polyols, in which polarity changes with size in opposite ways, was measured using attenuated total reflection IR spectroscopy. The results show that the partitioning of polyols monotonously decreases with size, whereas for alcohols it is not monotonous and slightly decreases for small C1-C3 alcohols followed by a sharp increase for larger alcohols. These results may be explained by assuming a heterogeneous structure of polyamide comprising a hydrophobic polyamide matrix and a polar internal aqueous phase. The partitioning data could consistently explain the results of rejection in standard filtration experiments. They clearly demonstrate that high/low partitioning may play a significant role in achieving a low/high rejection of organics. In particular, this points to the need to account for the partitioning effect while using molecular probes such as polyols or sugars for estimating the effective "pore" size or molecular weight cutoff of a membrane and for choosing/developing organic-rejecting membranes.

Two Examples of Transformations When There Are Possible Outliers.

DTIC Science & Technology

1981-01-01

potential outliers and, as in Carroll (1980), the influence function of A Is not bounded if k is monotone, A word of caution about "Hampel" is in order...normal linear model fits well. An acceptable analysis would thus estimate X as somewhere near I. As predicted by the influence function calculations in

Semiparametric Item Response Functions in the Context of Guessing

ERIC Educational Resources Information Center

Falk, Carl F.; Cai, Li

2016-01-01

We present a logistic function of a monotonic polynomial with a lower asymptote, allowing additional flexibility beyond the three-parameter logistic model. We develop a maximum marginal likelihood-based approach to estimate the item parameters. The new item response model is demonstrated on math assessment data from a state, and a computationally…

A Bayesian Beta-Mixture Model for Nonparametric IRT (BBM-IRT)

ERIC Educational Resources Information Center

Arenson, Ethan A.; Karabatsos, George

2017-01-01

Item response models typically assume that the item characteristic (step) curves follow a logistic or normal cumulative distribution function, which are strictly monotone functions of person test ability. Such assumptions can be overly-restrictive for real item response data. We propose a simple and more flexible Bayesian nonparametric IRT model…

Logic circuits from zero forcing.

PubMed

Burgarth, Daniel; Giovannetti, Vittorio; Hogben, Leslie; Severini, Simone; Young, Michael

We design logic circuits based on the notion of zero forcing on graphs; each gate of the circuits is a gadget in which zero forcing is performed. We show that such circuits can evaluate every monotone Boolean function. By using two vertices to encode each logical bit, we obtain universal computation. We also highlight a phenomenon of "back forcing" as a property of each function. Such a phenomenon occurs in a circuit when the input of gates which have been already used at a given time step is further modified by a computation actually performed at a later stage. Finally, we show that zero forcing can be also used to implement reversible computation. The model introduced here provides a potentially new tool in the analysis of Boolean functions, with particular attention to monotonicity. Moreover, in the light of applications of zero forcing in quantum mechanics, the link with Boolean functions may suggest a new directions in quantum control theory and in the study of engineered quantum spin systems. It is an open technical problem to verify whether there is a link between zero forcing and computation with contact circuits.

E-Index for Differentiating Complex Dynamic Traits

PubMed Central

Qi, Jiandong; Sun, Jianfeng; Wang, Jianxin

2016-01-01

While it is a daunting challenge in current biology to understand how the underlying network of genes regulates complex dynamic traits, functional mapping, a tool for mapping quantitative trait loci (QTLs) and single nucleotide polymorphisms (SNPs), has been applied in a variety of cases to tackle this challenge. Though useful and powerful, functional mapping performs well only when one or more model parameters are clearly responsible for the developmental trajectory, typically being a logistic curve. Moreover, it does not work when the curves are more complex than that, especially when they are not monotonic. To overcome this inadaptability, we therefore propose a mathematical-biological concept and measurement, E-index (earliness-index), which cumulatively measures the earliness degree to which a variable (or a dynamic trait) increases or decreases its value. Theoretical proofs and simulation studies show that E-index is more general than functional mapping and can be applied to any complex dynamic traits, including those with logistic curves and those with nonmonotonic curves. Meanwhile, E-index vector is proposed as well to capture more subtle differences of developmental patterns. PMID:27064292

Longitudinal variations of brain functional connectivity: A case report study based on a mouse model of epilepsy.

PubMed

Erramuzpe, A; Encinas, J M; Sierra, A; Maletic-Savatic, M; Brewster, A L; Anderson, Anne E; Stramaglia, S; Cortes, Jesus M

2015-01-01

Brain Functional Connectivity (FC) quantifies statistical dependencies between areas of the brain. FC has been widely used to address altered function of brain circuits in control conditions compared to different pathological states, including epilepsy, a major neurological disorder. However, FC also has the as yet unexplored potential to help us understand the pathological transformation of the brain circuitry. Our hypothesis is that FC can differentiate global brain interactions across a time-scale of days. To this end, we present a case report study based on a mouse model for epilepsy and analyze longitudinal intracranial electroencephalography data of epilepsy to calculate FC changes from the initial insult (status epilepticus) and over the latent period, when epileptogenic networks emerge, and at chronic epilepsy, when unprovoked seizures occur as spontaneous events. We found that the overall network FC at low frequency bands decreased immediately after status epilepticus was provoked, and increased monotonously later on during the latent period. Overall, our results demonstrate the capacity of FC to address longitudinal variations of brain connectivity across the establishment of pathological states.

On energetic prerequisites of attracting electrons

NASA Astrophysics Data System (ADS)

Sundholm, Dage

2014-06-01

The internal reorganization energy and the zero-point vibrational energy (ZPE) of fractionally charged molecules embedded in molecular materials are discussed. The theory for isolated open quantum systems is taken as the starting point. It is shown that for isolated molecules the internal reorganization-energy function and its slope, i.e., the chemical potential of an open molecular system are monotonically decreasing functions with respect to increasing amount of negative excess charge (q) in the range of q = [0, 1]. Calculations of the ZPE for fractionally charged molecules show that the ZPE may have a minimum for fractional occupation. The calculations show that the internal reorganization energy and changes in the ZPE are of the same order of magnitude with different behavior as a function of the excess charge. The sum of the contributions might favor molecules with fractional occupation of the molecular units and partial delocalization of the excess electrons in solid-state materials also when considering Coulomb repulsion between the excess electrons. The fractional electrons are then coherently distributed on many molecules of the solid-state material forming a condensate of attracting electrons, which is crucial for the superconducting state.

On energetic prerequisites of attracting electrons.

PubMed

Sundholm, Dage

2014-06-21

The internal reorganization energy and the zero-point vibrational energy (ZPE) of fractionally charged molecules embedded in molecular materials are discussed. The theory for isolated open quantum systems is taken as the starting point. It is shown that for isolated molecules the internal reorganization-energy function and its slope, i.e., the chemical potential of an open molecular system are monotonically decreasing functions with respect to increasing amount of negative excess charge (q) in the range of q = [0, 1]. Calculations of the ZPE for fractionally charged molecules show that the ZPE may have a minimum for fractional occupation. The calculations show that the internal reorganization energy and changes in the ZPE are of the same order of magnitude with different behavior as a function of the excess charge. The sum of the contributions might favor molecules with fractional occupation of the molecular units and partial delocalization of the excess electrons in solid-state materials also when considering Coulomb repulsion between the excess electrons. The fractional electrons are then coherently distributed on many molecules of the solid-state material forming a condensate of attracting electrons, which is crucial for the superconducting state.

Inequalities of extended beta and extended hypergeometric functions.

PubMed

Mondal, Saiful R

2017-01-01

We study the log-convexity of the extended beta functions. As a consequence, we establish Turán-type inequalities. The monotonicity, log-convexity, log-concavity of extended hypergeometric functions are deduced by using the inequalities on extended beta functions. The particular cases of those results also give the Turán-type inequalities for extended confluent and extended Gaussian hypergeometric functions. Some reverses of Turán-type inequalities are also derived.

Diffusion of Brownian particles in a tilted periodic potential under the influence of an external Ornstein-Uhlenbeck noise

NASA Astrophysics Data System (ADS)

Bai, Zhan-Wu; Zhang, Wei

2018-01-01

The diffusion behaviors of Brownian particles in a tilted periodic potential under the influence of an internal white noise and an external Ornstein-Uhlenbeck noise are investigated through numerical simulation. In contrast to the case when the bias force is smaller or absent, the diffusion coefficient exhibits a nonmonotonic dependence on the correlation time of the external noise when bias force is large. A mechanism different from locked-to-running transition theory is presented for the diffusion enhancement by a bias force in intermediate to large damping. In the underdamped regime and the presence of external noise, the diffusion coefficient is a monotonically decreasing function of low temperature rather than a nonmonotonic function when external noise is absent. The diffusive process undergoes four regimes when bias force approaches but is less than its critical value and noises intensities are small. These behaviors can be attributed to the locked-to-running transition of particles.

Investigation and appreciation of optimal output feedback. Volume 1: A convergent algorithm for the stochastic infinite-time discrete optimal output feedback problem

NASA Technical Reports Server (NTRS)

Halyo, N.; Broussard, J. R.

1984-01-01

The stochastic, infinite time, discrete output feedback problem for time invariant linear systems is examined. Two sets of sufficient conditions for the existence of a stable, globally optimal solution are presented. An expression for the total change in the cost function due to a change in the feedback gain is obtained. This expression is used to show that a sequence of gains can be obtained by an algorithm, so that the corresponding cost sequence is monotonically decreasing and the corresponding sequence of the cost gradient converges to zero. The algorithm is guaranteed to obtain a critical point of the cost function. The computational steps necessary to implement the algorithm on a computer are presented. The results are applied to a digital outer loop flight control problem. The numerical results for this 13th order problem indicate a rate of convergence considerably faster than two other algorithms used for comparison.

Resistivity and Resistivity Fluctuations of Thin Film Platinum-Aluminum Oxide Granular Metal-Insulator Composites

NASA Astrophysics Data System (ADS)

Mantese, Joseph Vito

Thin film metal-insulator composites were used to study how the resistivity and fluctuations in the resistivity were altered by changes in conduction mechanism so as to understand the source of the fluctuations and to better understand the conduction processes themselves. Metal-insulator composites were prepared by co -evaporation of platinum and aluminum oxide in a high vacuum system to create a series of films which had a range of metal volume fill fractions, p, from 23% to 100%. The samples were patterned using standard photolithographic techniques to form sample geometries of typical dimensions, length (TURN) 40(mu)m, width (TURN) 2(mu)m and thickness (TURN) 1500(ANGSTROM). The resistivity, (rho), and power spectral density of the resistivity fluctuations, S(,(rho))(f), were measured as a function of p and temperature, T. (rho)(p,T) was found to be a rapidly increasing function of decreasing p, rising monotonically by more than 7 orders of magnitude as p was decreased from 100% to 23%. For p (GREATERTHEQ) 59% the resistivity decreased linearly with decreasing temperature until limited by impurity scattering. The resistivities for the low metal fill fraction materials (p (LESSTHEQ) 50%) increased as the temperature was reduced as expected of thermally assisted tunneling conduction in metal-insulator composites. The transition from metallic conduction to thermally assisted tunneling occurred at a critical value, p(,c), between 59% and 50% Pt. For all samples at all p and T, S(,(rho))(f)(PROPORTIONAL)1/f('(alpha)) (1/f noise) with 0.8 (LESSTHEQ) (alpha) (LESSTHEQ) .1.2 and f the frequency in Hertz. No systematic dependence upon either p or T was found. The normalized noise intensity fS(,(rho))(f)/(rho)('2) (,1) (,Hz) was found to increase monotonically by 5 orders of magnitude with decreasing p then saturate at p(,c) where the conduction mechanism changed from metallic conduction to thermally assisted tunneling. Effective medium theory was used to analyze the role of charge tunneling on (rho)(p) and fS(,(rho))(f,p)/(rho)(p)('2) (,1 Hz). It was found that the experimental results could be interpreted in terms of a two component medium consisting of noisy tunnel junctions and quiet metallic particles. For p > p(,c) the continuous metallic paths served to short out some of the conductance fluctuations of the tunnel junctions without themselves adding significantly to the observed noise. For p < p(,c) both S(,(rho))(f) and (rho)('2) were dominated by tunneling. Thus it was concluded that the 1/f noise arose from local microscopic noise sources with the metal percolation network merely moderating the bulk noise intensity.

Maximum Marginal Likelihood Estimation of a Monotonic Polynomial Generalized Partial Credit Model with Applications to Multiple Group Analysis.

PubMed

Falk, Carl F; Cai, Li

2016-06-01

We present a semi-parametric approach to estimating item response functions (IRF) useful when the true IRF does not strictly follow commonly used functions. Our approach replaces the linear predictor of the generalized partial credit model with a monotonic polynomial. The model includes the regular generalized partial credit model at the lowest order polynomial. Our approach extends Liang's (A semi-parametric approach to estimate IRFs, Unpublished doctoral dissertation, 2007) method for dichotomous item responses to the case of polytomous data. Furthermore, item parameter estimation is implemented with maximum marginal likelihood using the Bock-Aitkin EM algorithm, thereby facilitating multiple group analyses useful in operational settings. Our approach is demonstrated on both educational and psychological data. We present simulation results comparing our approach to more standard IRF estimation approaches and other non-parametric and semi-parametric alternatives.

Transformations based on continuous piecewise-affine velocity fields

DOE PAGES

Freifeld, Oren; Hauberg, Soren; Batmanghelich, Kayhan; ...

2017-01-11

Here, we propose novel finite-dimensional spaces of well-behaved Rn → Rn transformations. The latter are obtained by (fast and highly-accurate) integration of continuous piecewise-affine velocity fields. The proposed method is simple yet highly expressive, effortlessly handles optional constraints (e.g., volume preservation and/or boundary conditions), and supports convenient modeling choices such as smoothing priors and coarse-to-fine analysis. Importantly, the proposed approach, partly due to its rapid likelihood evaluations and partly due to its other properties, facilitates tractable inference over rich transformation spaces, including using Markov-Chain Monte-Carlo methods. Its applications include, but are not limited to: monotonic regression (more generally, optimization overmore » monotonic functions); modeling cumulative distribution functions or histograms; time-warping; image warping; image registration; real-time diffeomorphic image editing; data augmentation for image classifiers. Our GPU-based code is publicly available.« less

Transformations Based on Continuous Piecewise-Affine Velocity Fields

PubMed Central

Freifeld, Oren; Hauberg, Søren; Batmanghelich, Kayhan; Fisher, Jonn W.

2018-01-01

We propose novel finite-dimensional spaces of well-behaved ℝn → ℝn transformations. The latter are obtained by (fast and highly-accurate) integration of continuous piecewise-affine velocity fields. The proposed method is simple yet highly expressive, effortlessly handles optional constraints (e.g., volume preservation and/or boundary conditions), and supports convenient modeling choices such as smoothing priors and coarse-to-fine analysis. Importantly, the proposed approach, partly due to its rapid likelihood evaluations and partly due to its other properties, facilitates tractable inference over rich transformation spaces, including using Markov-Chain Monte-Carlo methods. Its applications include, but are not limited to: monotonic regression (more generally, optimization over monotonic functions); modeling cumulative distribution functions or histograms; time-warping; image warping; image registration; real-time diffeomorphic image editing; data augmentation for image classifiers. Our GPU-based code is publicly available. PMID:28092517

Effects of Morphology Constraint on Electrophysiological Properties of Cortical Neurons

NASA Astrophysics Data System (ADS)

Zhu, Geng; Du, Liping; Jin, Lei; Offenhäusser, Andreas

2016-04-01

There is growing interest in engineering nerve cells in vitro to control architecture and connectivity of cultured neuronal networks or to build neuronal networks with predictable computational function. Pattern technologies, such as micro-contact printing, have been developed to design ordered neuronal networks. However, electrophysiological characteristics of the single patterned neuron haven’t been reported. Here, micro-contact printing, using polyolefine polymer (POP) stamps with high resolution, was employed to grow cortical neurons in a designed structure. The results demonstrated that the morphology of patterned neurons was well constrained, and the number of dendrites was decreased to be about 2. Our electrophysiological results showed that alterations of dendritic morphology affected firing patterns of neurons and neural excitability. When stimulated by current, though both patterned and un-patterned neurons presented regular spiking, the dynamics and strength of the response were different. The un-patterned neurons exhibited a monotonically increasing firing frequency in response to injected current, while the patterned neurons first exhibited frequency increase and then a slow decrease. Our findings indicate that the decrease in dendritic complexity of cortical neurons will influence their electrophysiological characteristics and alter their information processing activity, which could be considered when designing neuronal circuitries.

Resistance of virus to extinction on bottleneck passages: study of a decaying and fluctuating pattern of fitness loss

NASA Technical Reports Server (NTRS)

Lazaro, Ester; Escarmis, Cristina; Perez-Mercader, Juan; Manrubia, Susanna C.; Domingo, Esteban

2003-01-01

RNA viruses display high mutation rates and their populations replicate as dynamic and complex mutant distributions, termed viral quasispecies. Repeated genetic bottlenecks, which experimentally are carried out through serial plaque-to-plaque transfers of the virus, lead to fitness decrease (measured here as diminished capacity to produce infectious progeny). Here we report an analysis of fitness evolution of several low fitness foot-and-mouth disease virus clones subjected to 50 plaque-to-plaque transfers. Unexpectedly, fitness decrease, rather than being continuous and monotonic, displayed a fluctuating pattern, which was influenced by both the virus and the state of the host cell as shown by effects of recent cell passage history. The amplitude of the fluctuations increased as fitness decreased, resulting in a remarkable resistance of virus to extinction. Whereas the frequency distribution of fitness in control (independent) experiments follows a log-normal distribution, the probability of fitness values in the evolving bottlenecked populations fitted a Weibull distribution. We suggest that multiple functions of viral genomic RNA and its encoded proteins, subjected to high mutational pressure, interact with cellular components to produce this nontrivial, fluctuating pattern.

Spatio-temporal droplet size statistics in developing spray of starchy solution

NASA Astrophysics Data System (ADS)

Naz, Muhammad Yasin; Sulaiman, Shaharin Anwar; Ariwahjoedi, Bambang

2015-07-01

In the given research, the spray jet breakup of a modified starch solution was studied as a function of jet injection time and nozzle orifice diameter. The starch-urea-borax solution was prepared and tested with three axisymmetric full cone nozzles at service temperature of 80°C and the injection pressure of 5 bar. It is worth mentioning that no jet breakup was seen below these temperature and pressure values. The imaging studies on the time based spray evolution revealed monotonic increase in both; spray cone angle and tip penetration with an increase in injection time form 0-300 mm. Hereinafter, both parameters exhibited constants value over injection time. Phase Doppler Anemometry (PDA) measurements of the droplet size revealed significant decrease in the Sauter Mean Diameter (SMD) along the spray centerline. However, a steady decrease in SMD was seen towards the spray boundary. For fixed injection time of 300 ms, the overall SMD was decreased from 112 to 71 µm at 60 mm downstream, from 102 to 64 µm at 100 mm downstream and from 85 to 61 µm at 140 mm downstream with an increase in orifice diameter from 1.19 to 1.59 mm.

Material Damping Experiments at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Levine, Marie; White, Christopher

2003-01-01

A unique experimental facility has been designed to measure damping of materials at cryogenic temperatures. The test facility pays special attention to removing other sources of damping in the measurement by avoiding frictional interfaces, decoupling the test specimen from the support system, and by using a non-contacting measurement device; Damping data is obtained for materials (AI, GrEp, Be, Fused Quartz), strain amplitudes (less than 10-6 ppm), frequencies (20Hz-330Hz) and temperatures (20K-293K) relevant to future precision optical space missions. The test data shows a significant decrease in viscous damping at cryogenic temperatures and can be as low as 10-4%, but the amount of the damping decrease is a function of frequency and material. Contrary to the other materials whose damping monotonically decreased with temperature, damping of Fused Quartz increased substantially at cryo, after reaching a minimum at around l50 K. The damping is also shown to be insensitive to strain for low strain levels. At room temperatures, the test data correlates well to the analytical predictions of the Zener damping model. Discrepancies at cryogenic temperatures between the model predictions and the test data are observed.

Flicker sensitivity as a function of target area with and without temporal noise.

PubMed

Rovamo, J; Donner, K; Näsänen, R; Raninen, A

2000-01-01

Flicker sensitivities (1-30 Hz) in foveal, photopic vision were measured as functions of stimulus area with and without strong external white temporal noise. Stimuli were circular, sinusoidally flickering sharp-edged spots of variable diameters (0.25-4 degrees ) but constant duration (2 s), surrounded by a uniform equiluminant field. The data was described with a model comprising (i) low-pass filtering in the retina (R), with a modulation transfer function (MTF) of a form derived from responses of cones; (ii) normalisation of the temporal luminance distribution by the average luminance; (iii) high-pass filtering by postreceptoral neural pathways (P), with an MTF proportional to temporal frequency; (iv) addition of internal white neural noise (N(i)); (v) integration over a spatial window; and (vi) detection by a suboptimal temporal matched filter of efficiency eta. In strong external noise, flicker sensitivity was independent of spot area. Without external noise, sensitivity increased with the square root of stimulus area (Piper's law) up to a critical area (A(c)), where it reaches a maximum level (S(max)). Both A(c) and eta were monotonic functions of temporal frequency (f), such that log A(c) increased and log eta decreased linearly with log f. Remarkably, the increase in spatial integration area and the decrease in efficiency were just balanced, so A(c)(f)eta(f) was invariant against f. Thus the bandpass characteristics of S(max)(f) directly reflected the composite effect of the distal filters R(f) and P(f). The temporal equivalent (N(it)) of internal neural noise (N(i)) decreased in inverse proportion to spot area up to A(c) and then stayed constant indicating that spatially homogeneous signals and noise are integrated over the same area.

Nonconvex Nonsmooth Low Rank Minimization via Iteratively Reweighted Nuclear Norm.

PubMed

Lu, Canyi; Tang, Jinhui; Yan, Shuicheng; Lin, Zhouchen

2016-02-01

The nuclear norm is widely used as a convex surrogate of the rank function in compressive sensing for low rank matrix recovery with its applications in image recovery and signal processing. However, solving the nuclear norm-based relaxed convex problem usually leads to a suboptimal solution of the original rank minimization problem. In this paper, we propose to use a family of nonconvex surrogates of L0-norm on the singular values of a matrix to approximate the rank function. This leads to a nonconvex nonsmooth minimization problem. Then, we propose to solve the problem by an iteratively re-weighted nuclear norm (IRNN) algorithm. IRNN iteratively solves a weighted singular value thresholding problem, which has a closed form solution due to the special properties of the nonconvex surrogate functions. We also extend IRNN to solve the nonconvex problem with two or more blocks of variables. In theory, we prove that the IRNN decreases the objective function value monotonically, and any limit point is a stationary point. Extensive experiments on both synthesized data and real images demonstrate that IRNN enhances the low rank matrix recovery compared with the state-of-the-art convex algorithms.

Surface sensitization mechanism on negative electron affinity p-GaN nanowires

NASA Astrophysics Data System (ADS)

Diao, Yu; Liu, Lei; Xia, Sihao; Feng, Shu; Lu, Feifei

2018-03-01

The surface sensitization is the key to prepare negative electron affinity photocathode. The thesis emphasizes on the study of surface sensitization mechanism of p-type doping GaN nanowires utilizing first principles based on density function theory. The adsorption energy, work function, dipole moment, geometry structure, electronic structure and optical properties of Mg-doped GaN nanowires surfaces with various coverages of Cs atoms are investigated. The GaN nanowire with Mg doped in core position is taken as the sensitization base. At the initial stage of sensitization, the best adsorption site for Cs atom on GaN nanowire surface is BN, the bridge site of two adjacent N atoms. Surface sensitization generates a p-type internal surface with an n-type surface state, introducing a band bending region which can help reduce surface barrier and work function. With increasing Cs coverage, work functions decrease monotonously and the "Cs-kill" phenomenon disappears. For Cs coverage of 0.75 ML and 1 ML, the corresponding sensitization systems reach negative electron affinity state. Through surface sensitization, the absorption curves are red shifted and the absorption coefficient is cut down. All theoretical calculations can guide the design of negative electron affinity Mg doped GaN nanowires photocathode.

Experimental evidence of the decrease of kinetic energy of hadrons in passing through atomic nuclei

NASA Technical Reports Server (NTRS)

Strugalski, Z.

1985-01-01

Hadrons with kinetic energies higher than the pion production threshold lose their kinetic energies monotonically in traversing atomic nuclei, due to the strong interactions in nuclear matter. This phenomenon is a crude analogy to the energy loss of charged particles in their passage through materials. Experimental evidence is presented.

Normal-metal quasiparticle traps for superconducting qubits

NASA Astrophysics Data System (ADS)

Riwar, R.-P.; Hosseinkhani, A.; Burkhart, L. D.; Gao, Y. Y.; Schoelkopf, R. J.; Glazman, L. I.; Catelani, G.

2016-09-01

The presence of quasiparticles in superconducting qubits emerges as an intrinsic constraint on their coherence. While it is difficult to prevent the generation of quasiparticles, keeping them away from active elements of the qubit provides a viable way of improving the device performance. Here we develop theoretically and validate experimentally a model for the effect of a single small trap on the dynamics of the excess quasiparticles injected in a transmon-type qubit. The model allows one to evaluate the time it takes to evacuate the injected quasiparticles from the transmon as a function of trap parameters. With the increase of the trap size, this time decreases monotonically, saturating at the level determined by the quasiparticles diffusion constant and the qubit geometry. We determine the characteristic trap size needed for the relaxation time to approach that saturation value.

Theoretical analyses of Baroclinic flows

NASA Technical Reports Server (NTRS)

Antar, B.

1982-01-01

A stability analysis of a thin horizontal rotating fluid layer which is subjected to arbitrary horizontal and vertical temperature gradients is presented. The basic state is a nonlinear Hadley cell which contains both Ekman and thermal boundary layers; it is given in closed form. The stability analysis is based on the linearized Navier-Stokes equations, and zonally symmetric perturbations in the form of waves propagating in the meridional direction are considered. Numerical methods were used for the stability problem. It was found that the instability sets in when the Richardson number is close to unity and that the critical Richardson number is a non-monotonic function of the Prandtl number. Further, it was found that the critical Richardson number decreases with increasing Ekman number until a critical value of the Ekman number is reached beyond which the fluid is stable.

Analysis of single-layer metamaterial absorber with reflection theory

NASA Astrophysics Data System (ADS)

Xiong, Han; Tang, Ming-Chun; Hong, Jing-Song

2015-04-01

A reflection theory is employed to analyze a single-layered metamaterial absorber. With the necessary conditions for zero reflection, the permittivity and permeability as functions of absorptivity were obtained, which are suitable for analyzing the absorption properties of single-layered metamaterial absorber at both normal and oblique incidence cases. With the obtained expressions, it not only can explain why the absorption peaks monotonously decrease with increasing of the incident angles but also can explore the relationship between the absorptivity and spacer thickness of the dielectric slab. A Jerusalem cross metamaterial absorber was simulated and verified the validity of this proposed reflection theory. The main contribution of our work is that it can explain the physical mechanism of the various absorption peaks by using the analytical formula and highlights its potential guidance for designing and analyzing metamaterial absorbers in the future.

Semi-Parametric Item Response Functions in the Context of Guessing. CRESST Report 844

ERIC Educational Resources Information Center

Falk, Carl F.; Cai, Li

2015-01-01

We present a logistic function of a monotonic polynomial with a lower asymptote, allowing additional flexibility beyond the three-parameter logistic model. We develop a maximum marginal likelihood based approach to estimate the item parameters. The new item response model is demonstrated on math assessment data from a state, and a computationally…

Suppression effects in feature-based attention

PubMed Central

Wang, Yixue; Miller, James; Liu, Taosheng

2015-01-01

Attending to a feature enhances visual processing of that feature, but it is less clear what occurs to unattended features. Single-unit recording studies in middle temporal (MT) have shown that neuronal modulation is a monotonic function of the difference between the attended and neuron's preferred direction. Such a relationship should predict a monotonic suppressive effect in psychophysical performance. However, past research on suppressive effects of feature-based attention has remained inconclusive. We investigated the suppressive effect for motion direction, orientation, and color in three experiments. We asked participants to detect a weak signal among noise and provided a partially valid feature cue to manipulate attention. We measured performance as a function of the offset between the cued and signal feature. We also included neutral trials where no feature cues were presented to provide a baseline measure of performance. Across three experiments, we consistently observed enhancement effects when the target feature and cued feature coincided and suppression effects when the target feature deviated from the cued feature. The exact profile of suppression was different across feature dimensions: Whereas the profile for direction exhibited a “rebound” effect, the profiles for orientation and color were monotonic. These results demonstrate that unattended features are suppressed during feature-based attention, but the exact suppression profile depends on the specific feature. Overall, the results are largely consistent with neurophysiological data and support the feature-similarity gain model of attention. PMID:26067533

Inverting Monotonic Nonlinearities by Entropy Maximization

PubMed Central

López-de-Ipiña Pena, Karmele; Caiafa, Cesar F.

2016-01-01

This paper proposes a new method for blind inversion of a monotonic nonlinear map applied to a sum of random variables. Such kinds of mixtures of random variables are found in source separation and Wiener system inversion problems, for example. The importance of our proposed method is based on the fact that it permits to decouple the estimation of the nonlinear part (nonlinear compensation) from the estimation of the linear one (source separation matrix or deconvolution filter), which can be solved by applying any convenient linear algorithm. Our new nonlinear compensation algorithm, the MaxEnt algorithm, generalizes the idea of Gaussianization of the observation by maximizing its entropy instead. We developed two versions of our algorithm based either in a polynomial or a neural network parameterization of the nonlinear function. We provide a sufficient condition on the nonlinear function and the probability distribution that gives a guarantee for the MaxEnt method to succeed compensating the distortion. Through an extensive set of simulations, MaxEnt is compared with existing algorithms for blind approximation of nonlinear maps. Experiments show that MaxEnt is able to successfully compensate monotonic distortions outperforming other methods in terms of the obtained Signal to Noise Ratio in many important cases, for example when the number of variables in a mixture is small. Besides its ability for compensating nonlinearities, MaxEnt is very robust, i.e. showing small variability in the results. PMID:27780261

Inverting Monotonic Nonlinearities by Entropy Maximization.

PubMed

Solé-Casals, Jordi; López-de-Ipiña Pena, Karmele; Caiafa, Cesar F

2016-01-01

This paper proposes a new method for blind inversion of a monotonic nonlinear map applied to a sum of random variables. Such kinds of mixtures of random variables are found in source separation and Wiener system inversion problems, for example. The importance of our proposed method is based on the fact that it permits to decouple the estimation of the nonlinear part (nonlinear compensation) from the estimation of the linear one (source separation matrix or deconvolution filter), which can be solved by applying any convenient linear algorithm. Our new nonlinear compensation algorithm, the MaxEnt algorithm, generalizes the idea of Gaussianization of the observation by maximizing its entropy instead. We developed two versions of our algorithm based either in a polynomial or a neural network parameterization of the nonlinear function. We provide a sufficient condition on the nonlinear function and the probability distribution that gives a guarantee for the MaxEnt method to succeed compensating the distortion. Through an extensive set of simulations, MaxEnt is compared with existing algorithms for blind approximation of nonlinear maps. Experiments show that MaxEnt is able to successfully compensate monotonic distortions outperforming other methods in terms of the obtained Signal to Noise Ratio in many important cases, for example when the number of variables in a mixture is small. Besides its ability for compensating nonlinearities, MaxEnt is very robust, i.e. showing small variability in the results.

Topology Property and Dynamic Behavior of a Growing Spatial Network

NASA Astrophysics Data System (ADS)

Cao, Xian-Bin; Du, Wen-Bo; Hu, Mao-Bin; Rong, Zhi-Hai; Sun, Peng; Chen, Cai-Long

In this paper, we propose a growing spatial network (GSN) model and investigate its topology properties and dynamical behaviors. The model is generated by adding one node i with m links into a square lattice at each time step and the new node i is connected to the existing nodes with probabilities proportional to: ({kj})α /dij2, where kj is the degree of node j, α is the tunable parameter and dij is the Euclidean distance between i and j. It is found that both the degree heterogeneity and the clustering coefficient monotonously increase with the increment of α, while the average shortest path length monotonously decreases. Moreover, the evolutionary game dynamics and network traffic dynamics are investigated. Simulation results show that the value of α can also greatly influence the dynamic behaviors.

Zone compensated multilayer laue lens and apparatus and method of fabricating the same

DOEpatents

Conley, Raymond P.; Liu, Chian Qian; Macrander, Albert T.; Yan, Hanfei; Maser, Jorg; Kang, Hyon Chol; Stephenson, Gregory Brian

2015-07-14

A multilayer Laue Lens includes a compensation layer formed in between a first multilayer section and a second multilayer section. Each of the first and second multilayer sections includes a plurality of alternating layers made of a pair of different materials. Also, the thickness of layers of the first multilayer section is monotonically increased so that a layer adjacent the substrate has a minimum thickness, and the thickness of layers of the second multilayer section is monotonically decreased so that a layer adjacent the compensation layer has a maximum thickness. In particular, the compensation layer of the multilayer Laue lens has an in-plane thickness gradient laterally offset by 90.degree. as compared to other layers in the first and second multilayer sections, thereby eliminating the strict requirement of the placement error.

Solute-solvent cavity and bridge functions. I. Varying size of the solute

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

Vyalov, I., E-mail: ivan.vyalov@iit.it; Chuev, G., E-mail: genchuev@rambler.ru; Georgi, N., E-mail: georgi@mis.mpg.de

2014-08-21

In this work we present the results of the extensive molecular simulations of solute-solvent cavity and bridge functions. The mixtures of Lennard-Jones solvent with Lennard-Jones solute at infinite dilution are considered for different solute-solvent size ratios—up to 4:1. The Percus-Yevick and hypernetted chain closures deviate substantially from simulation results in the investigated temperature and density ranges. We also find that the behavior of the indirect and cavity correlation functions is non-monotonous within the hard-core region, but the latter can be successfully approximated by mean-field theory if the solute-solvent interaction energy is divided into repulsive and attractive contribution, according to Weeks-Chandler-Andersenmore » theory. Furthermore, in spite of the non-monotonous behavior of logarithm of the cavity function and the indirect correlation function, their difference, i.e., the bridge function remains constant within the hard-core region. Such behavior of the bridge and indirect correlation functions at small distances and for small values of indirect correlation function is well known from the Duh-Haymet plots, where the non-unique relationship results in loops of the bridge function vs. indirect correlation function graphs. We show that the same pathological behavior appears also when distance is small and indirect correlation function is large. We further show that the unique functional behavior of the bridge function can be established when bridge is represented as a function of the renormalized, repulsive indirect correlation function.« less

Dispersion in 2D network: Effects of mixing rule at nodes and molecular diffusion

NASA Astrophysics Data System (ADS)

Wang, Y.; Tao, Q.; Li, M.

2017-12-01

We simulate solute transport in 2D network backbone characterized by pore connectivity and pore heterogeneity by particle-tracking method. In order to ensure the dispersion coefficient reaching an asymptotic value, we upscale dispersion from pore-scale to meter-scale by using periodic boundary condition. As comparison, two different flow mechanisms without or with dispersion in a capillary tube, namely mean flow and Taylor-Aris dispersion, are introduced to investigate the evolution of solute spreading. The longitudinal dispersion coefficient DLM without dispersion in a pipe can roughly be regarded as a parameter to quantify the impact of microscopic structure of porous media on solute spreading, which is smaller than that value DL of Taylor-Aris dispersion. The difference between them decreases with the enhancement of the disorder. The mixing rule at nodes has a minor effect on longitudinal spreading, but has a significant effect on transverse spreading, especially for the nearly homogeneous media. An increase of the disorder in network achieved by increasing pore size heterogeneity or/and decreasing pore connectivity diminishes the difference between two mixing rules. Besides, the evolution of longitudinal dispersion coefficient over diffusion presents three different patterns at different velocities for homogenous media, such as monotonically increasing trend, decreasing first and then increasing trend and monotonically decreasing trend. But all are replaced by power law for a high disorder. The simulation results also accurately predict the experimental dependence of the longitudinal coefficient on Peclet number Pe.

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

Burke, K.; Smith, J. C.; Grabowski, P. E.

Universal exact conditions guided the construction of most ground-state density functional approximations in use today. Here, we derive the relation between the entropy and Mermin free energy density functionals for thermal density functional theory. Both the entropy and sum of kinetic and electron-electron repulsion functionals are shown to be monotonically increasing with temperature, while the Mermin functional is concave downwards. Analogous relations are found for both exchange and correlation. The importance of these conditions is illustrated in two extremes: the Hubbard dimer and the uniform gas.

Effects of temperature on consumer-resource interactions.

PubMed

Amarasekare, Priyanga

2015-05-01

Understanding how temperature variation influences the negative (e.g. self-limitation) and positive (e.g. saturating functional responses) feedback processes that characterize consumer-resource interactions is an important research priority. Previous work on this topic has yielded conflicting outcomes with some studies predicting that warming should increase consumer-resource oscillations and others predicting that warming should decrease consumer-resource oscillations. Here, I develop a consumer-resource model that both synthesizes previous findings in a common framework and yields novel insights about temperature effects on consumer-resource dynamics. I report three key findings. First, when the resource species' birth rate exhibits a unimodal temperature response, as demonstrated by a large number of empirical studies, the temperature range over which the consumer-resource interaction can persist is determined by the lower and upper temperature limits to the resource species' reproduction. This contrasts with the predictions of previous studies, which assume that the birth rate exhibits a monotonic temperature response, that consumer extinction is determined by temperature effects on consumer species' traits, rather than the resource species' traits. Secondly, the comparative analysis I have conducted shows that whether warming leads to an increase or decrease in consumer-resource oscillations depends on the manner in which temperature affects intraspecific competition. When the strength of self-limitation increases monotonically with temperature, warming causes a decrease in consumer-resource oscillations. However, if self-limitation is strongest at temperatures physiologically optimal for reproduction, a scenario previously unanalysed by theory but amply substantiated by empirical data, warming can cause an increase in consumer-resource oscillations. Thirdly, the model yields testable comparative predictions about consumer-resource dynamics under alternative hypotheses for how temperature affects competitive and resource acquisition traits. Importantly, it does so through empirically quantifiable metrics for predicting temperature effects on consumer viability and consumer-resource oscillations, which obviates the need for parameterizing complex dynamical models. Tests of these metrics with empirical data on a host-parasitoid interaction yield realistic estimates of temperature limits for consumer persistence and the propensity for consumer-resource oscillations, highlighting their utility in predicting temperature effects, particularly warming, on consumer-resource interactions in both natural and agricultural settings. © 2014 The Author. Journal of Animal Ecology © 2014 British Ecological Society.

Duration as a measure of the spiral aftereffect.

DOT National Transportation Integrated Search

1963-01-01

Describes an experiment that studied the reliability of duration as a measure of the spiral aftereffect. The results for 10 Ss indicate that duration is a highly reliable measure and that duration is a simple monotonic function of exposure-time.

Clustering and relative velocity of heavy particles under gravitational settling in isotropic turbulent flows

NASA Astrophysics Data System (ADS)

Jin, Guodong; He, Guo-Wei

2015-11-01

Clustering and intermittency in radial relative velocity (RRV) of heavy particles of same size settling in turbulent flows can be remarkably changed due to gravity. Clustering is monotonically reduced at Stokes number less than 1 under gravity due to the disability of the centrifugal mechanism, however it is non-monotonically enhanced at Stokes number greater than 1 due to the multiplicative amplification in the case that the proposed effective Kubo number is less than 1. Although gravity causes monotonical reduction in the rms of RRV of particles at a given Stokes number with decreasing Froude number, the variation tendency in the tails of standardized PDF of RRV versus Froude number is obviously different: the tails become narrower at a small Stokes number, while they become broader at a large Stokes number. The mechanism of this variation stems from the compromise between the following two competing factors. The mitigation of correlation of particle positions and the regions of high strain rate which are more intermittent reduces the intermittency in RRV at small Stokes numbers, while the significant reduction in the backward-in-time relative separations will make particle pairs see small-scale structures, leading to a higher intermittency in RRV at large Stokes numbers. NSAF of China (grant number U1230126); NSFC (grant numbers 11072247 and 11232011).

Effect of gold nanoparticles on the fluorescence excitation spectrum of α-fetoprotein: Local environment dependent fluorescence quenching

NASA Astrophysics Data System (ADS)

Li, Jian-jun; Chen, Yu; Wang, A.-qing; Zhu, Jian; Zhao, Jun-wu

2011-01-01

The effect of colloid gold nanoparticles (AuNPs) on the fluorescence excitation spectrum of α-fetoprotein (AFP) has been investigated experimentally. The excitation spectral peaks of AFP with low concentration from 0.01 ng ml -1 to 12 ng ml -1 increase monotonically with increasing of AFP concentration. When some gold colloids were added to the AFP solution, the excitation peak at 285 nm decreases distinctly. By comparing the excitation peak intensity of AFP solution with gold colloids and without gold colloids at different AFP concentrations, the quenching effect from gold nanoparticle was more effective at lower AFP concentration. So the range of concentration from 0.01 ng ml -1 to 0.09 ng ml -1 will be the potential range of applications because of the higher sensitivity. The physical origin based on local field effect was investigated to illuminate this local environment dependent fluorescence quenching. The changing extent of quenching with different AFP concentrations can be attributed to the nonlinear decreasing of the local field factor of gold nanoparticles as a function of environmental dielectric constant.

Diameter Dependence of Planar Defects in InP Nanowires

PubMed Central

Wang, Fengyun; Wang, Chao; Wang, Yiqian; Zhang, Minghuan; Han, Zhenlian; Yip, SenPo; Shen, Lifan; Han, Ning; Pun, Edwin Y. B.; Ho, Johnny C.

2016-01-01

In this work, extensive characterization and complementary theoretical analysis have been carried out on Au-catalyzed InP nanowires in order to understand the planar defect formation as a function of nanowire diameter. From the detailed transmission electron microscopic measurements, the density of stacking faults and twin defects are found to monotonically decrease as the nanowire diameter is decreased to 10 nm, and the chemical analysis clearly indicates the drastic impact of In catalytic supersaturation in Au nanoparticles on the minimized planar defect formation in miniaturized nanowires. Specifically, during the chemical vapor deposition of InP nanowires, a significant amount of planar defects is created when the catalyst seed sizes are increased with the lower degree of In supersaturation as dictated by the Gibbs-Thomson effect, and an insufficient In diffusion (or Au-rich enhancement) would lead to a reduced and non-uniform In precipitation at the NW growing interface. The results presented here provide an insight into the fabrication of “bottom-up” InP NWs with minimized defect concentration which are suitable for various device applications. PMID:27616584

Diameter Dependence of Planar Defects in InP Nanowires.

PubMed

Wang, Fengyun; Wang, Chao; Wang, Yiqian; Zhang, Minghuan; Han, Zhenlian; Yip, SenPo; Shen, Lifan; Han, Ning; Pun, Edwin Y B; Ho, Johnny C

2016-09-12

In this work, extensive characterization and complementary theoretical analysis have been carried out on Au-catalyzed InP nanowires in order to understand the planar defect formation as a function of nanowire diameter. From the detailed transmission electron microscopic measurements, the density of stacking faults and twin defects are found to monotonically decrease as the nanowire diameter is decreased to 10 nm, and the chemical analysis clearly indicates the drastic impact of In catalytic supersaturation in Au nanoparticles on the minimized planar defect formation in miniaturized nanowires. Specifically, during the chemical vapor deposition of InP nanowires, a significant amount of planar defects is created when the catalyst seed sizes are increased with the lower degree of In supersaturation as dictated by the Gibbs-Thomson effect, and an insufficient In diffusion (or Au-rich enhancement) would lead to a reduced and non-uniform In precipitation at the NW growing interface. The results presented here provide an insight into the fabrication of "bottom-up" InP NWs with minimized defect concentration which are suitable for various device applications.

Efficiency of ETV diagrams as diagnostic tools for long-term period variations. II. Non-conservative mass transfer, and gravitational radiation

NASA Astrophysics Data System (ADS)

Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.

2015-03-01

Context. The credibility of an eclipse timing variation (ETV) diagram analysis is investigated for various manifestations of the mass transfer and gravitational radiation processes in binary systems. The monotonicity of the period variations and the morphology of the respective ETV diagrams are thoroughly explored in both the direct impact and the accretion disk mode of mass transfer, accompanied by different types of mass and angular momentum losses (through a hot-spot emission from the gainer and via the L2/L3 points). Aims: Our primary objective concerns the traceability of each physical mechanism by means of an ETV diagram analysis. Also, possible critical mass ratio values are sought for those transfer modes that involve orbital angular momentum losses strong enough to dictate the secular period changes even when highly competitive mechanisms with the opposite direction act simultaneously. Methods: The dot{J-dot{P}} relation that governs the orbital evolution of a binary system is set to provide the exact solution for the period and the function expected to represent the subsequent eclipse timing variations. The angular momentum transport is parameterized through appropriate empirical relations, which are inferred from semi-analytical ballistic models. Then, we numerically determine the minimum temporal range over which a particular mechanism is rendered measurable, as well as the critical mass ratio values that signify monotonicity inversion in the period modulations. Results: Mass transfer rates comparable to or greater than 10-8 M⊙ yr-1 are measurable for typical noise levels of the ETV diagrams, regardless of whether the process is conservative. However, the presence of a transient disk around the more massive component defines a critical mass ratio (qcr ≈ 0.83) above which the period turns out to decrease when still in the conservative regime, rendering the measurability of the anticipated variations a much more complicated task. The effects of gravitational radiation proved to be rather undetectable, except for systems with physical characteristics that only refer to cataclysmic variables. Conclusions: The monotonicity of the period variations and the curvature of the respective ETV diagrams depend strongly on the accretion mode and the degree of conservatism of the transfer process. Unlike the hot-spot effects, the Lagrangian points L2 and L3 support very efficient routes of strong angular momentum loss. It is further shown that escape of mass via the L3 point - when the donor is the less massive component - safely provides critical mass ratios above which the period is expected to decrease, no matter how intense the process is.

Lung tumor segmentation in PET images using graph cuts.

PubMed

Ballangan, Cherry; Wang, Xiuying; Fulham, Michael; Eberl, Stefan; Feng, David Dagan

2013-03-01

The aim of segmentation of tumor regions in positron emission tomography (PET) is to provide more accurate measurements of tumor size and extension into adjacent structures, than is possible with visual assessment alone and hence improve patient management decisions. We propose a segmentation energy function for the graph cuts technique to improve lung tumor segmentation with PET. Our segmentation energy is based on an analysis of the tumor voxels in PET images combined with a standardized uptake value (SUV) cost function and a monotonic downhill SUV feature. The monotonic downhill feature avoids segmentation leakage into surrounding tissues with similar or higher PET tracer uptake than the tumor and the SUV cost function improves the boundary definition and also addresses situations where the lung tumor is heterogeneous. We evaluated the method in 42 clinical PET volumes from patients with non-small cell lung cancer (NSCLC). Our method improves segmentation and performs better than region growing approaches, the watershed technique, fuzzy-c-means, region-based active contour and tumor customized downhill. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Means and the Mean Value Theorem

ERIC Educational Resources Information Center

Merikoski, Jorma K.; Halmetoja, Markku; Tossavainen, Timo

2009-01-01

Let I be a real interval. We call a continuous function [mu] : I x I [right arrow] [Bold R] a proper mean if it is symmetric, reflexive, homogeneous, monotonic and internal. Let f : I [right arrow] [Bold R} be a differentiable and strictly convex or strictly concave function. If a, b [image omitted] I with a [not equal to] b, then there exists a…

Non-monotonic changes in performance with eccentricity modeled by multiple eccentricity-dependent limitations.

PubMed

Poirier, Frédéric J A M; Gurnsey, Rick

2005-08-01

Eccentricity-dependent resolution losses are sometimes compensated for in psychophysical experiments by magnifying (scaling) stimuli at each eccentricity. The use of either pre-selected scaling factors or unscaled stimuli sometimes leads to non-monotonic changes in performance as a function of eccentricity. We argue that such non-monotonic changes arise when performance is limited by more than one type of constraint at each eccentricity. Building on current methods developed to investigate peripheral perception [e.g., Watson, A. B. (1987). Estimation of local spatial scale. Journal of the Optical Society of America A, 4 (8), 1579-1582; Poirier, F. J. A. M., & Gurnsey, R. (2002). Two eccentricity dependent limitations on subjective contour discrimination. Vision Research, 42, 227-238; Strasburger, H., Rentschler, I., & Harvey Jr., L. O. (1994). Cortical magnification theory fails to predict visual recognition. European Journal of Neuroscience, 6, 1583-1588], we show how measured scaling can deviate from a linear function of eccentricity in a grating acuity task [Thibos, L. N., Still, D. L., & Bradley, A. (1996). Characterization of spatial aliasing and contrast sensitivity in peripheral vision. Vision Research, 36(2), 249-258]. This framework can also explain the central performance drop [Kehrer, L. (1989). Central performance drop on perceptual segregation tasks. Spatial Vision, 4, 45-62] and a case of "reverse scaling" of the integration window in symmetry [Tyler, C. W. (1999). Human symmetry detection exhibits reverse eccentricity scaling. Visual Neuroscience, 16, 919-922]. These cases of non-monotonic performance are shown to be consistent with multiple sources of resolution loss, each of which increases linearly with eccentricity. We conclude that most eccentricity research, including "oddities", can be explained by multiple-scaling theory as extended here, where the receptive field properties of all underlying mechanisms in a task increase in size with eccentricity, but not necessarily at the same rate.

Distribution of the Crystalline Lens Power In Vivo as a Function of Age.

PubMed

Jongenelen, Sien; Rozema, Jos J; Tassignon, Marie-José

2015-11-01

To observe the age-related changes in crystalline lens power in vivo in a noncataractous European population. Data were obtained though Project Gullstrand, a multicenter population study with data from healthy phakic subjects between 20 and 85 years old. One randomly selected eye per subject was used. Lens power was calculated using the modified Bennett-Rabbetts method, using biometry data from an autorefractometer, Oculus Pentacam, and Haag-Streit Lenstar. The study included 1069 Caucasian subjects (490 men, 579 women) with a mean age of 44.2 ± 14.2 years and mean lens power of 24.96 ± 2.18 diopters (D). The average lens power showed a statistically significant decrease as a function of age, with a steeper rate of decrease after the age of 55. The highest crystalline lens power was found in emmetropic eyes and eyes with a short axial length. The correlation of lens power with different refractive components was statistically significant for axial length (r = -0.523, P < 0.01) and anterior chamber depth (r = -0.161, P < 0.01), but not for spherical equivalent and corneal power (P > 0.05). This in vivo study showed a monotonous decrease in crystalline lens power with age, with a steeper decline after 55 years. While this finding fundamentally concurs with previous in vivo studies, it is at odds with studies performed on donor eyes that reported lens power increases after the age of 55.

Effect of capping layer on spin-orbit torques

NASA Astrophysics Data System (ADS)

Sun, Chi; Siu, Zhuo Bin; Tan, Seng Ghee; Yang, Hyunsoo; Jalil, Mansoor B. A.

2018-04-01

In order to enhance the magnitude of spin-orbit torque (SOT), considerable experimental works have been devoted to studying the thickness dependence of the different layers in multilayers consisting of heavy metal (HM), ferromagnet (FM), and capping layers. Here, we present a theoretical model based on the spin-drift-diffusion formalism to investigate the effect of the capping layer properties such as its thickness on the SOT observed in experiments. It is found that the spin Hall-induced SOT can be significantly enhanced by incorporating a capping layer with an opposite spin Hall angle to that of the HM layer. The spin Hall torque can be maximized by tuning the capping layer thickness. However, in the absence of the spin Hall effect (SHE) in the capping layer, the torque decreases monotonically with the capping layer thickness. Conversely, the spin Hall torque is found to decrease monotonically with the FM layer thickness, irrespective of the presence or absence of the SHE in the capping layer. All these trends are in correspondence with experimental observations. Finally, our model suggests that capping layers with a long spin diffusion length and high resistivity would also enhance the spin Hall torque.

The V1V2 EOS for Detonation Products

NASA Astrophysics Data System (ADS)

Partom, Yehuda

2010-10-01

Many equations of state (EOS) for detonation products have been proposed and used. Some of them are in analytical form and some in tabular form. The most popular is the Jones-Wilkins-Lee (JWL) EOS. One of the main parameters of a product's EOS is the so-called adiabatic gamma along its main isentrope (γs). For JWL EOSs γs(V) varies in a nonmonotonic way. Going down from the CJ point along the main isentrope, it first increases to create a hump, and then, as V goes to infinity, gamma decreases to perfect gas-like behavior with gamma around 1.3. But according to Davis [1], γs(V) should decrease monotonically with V. Accordingly, in this article we investigate the following: (1) Is the hump in γs(V) necessary? and (2) Is it possible to construct a product's EOS with a monotonic γs(V) that is consistent with experimental data? We find that (1) it is possible to construct a product's EOS without a hump in γs(V); and (2) without a hump in γs(V) there are not enough degrees of freedom to reproduce cylinder test data.

The noble gases: how their electronegativity and hardness determines their chemistry.

PubMed

Furtado, Jonathan; De Proft, Frank; Geerlings, Paul

2015-02-26

The establishment of an internally consistent scale of noble gas electronegativities is a long-standing problem. In the present study, the problem is attacked via the Mulliken definition, which in recent years gained widespread use to its natural appearance in the context of conceptual density functional theory. Basic ingredients of this scale are the electron affinity and the ionization potential. Whereas the latter can be computed routinely, the instability of the anion makes the judicious choice of computational technique for evaluating electron affinities much more tricky. We opted for Puiatti's approach, extrapolating the energy of high ε solvent stabilized anions to the ε = 1 (gas phase) case. The results give negative electron affinity values, monotonically increasing (except for helium which is an outlier in most of the story) to almost zero at eka-radon in agreement with high level calculations. The stability of the B3LYP results is successfully tested both via improving the level of theory (CCSD(T)) and expanding the basis set. Combined with the ionization energies (in good agreement with experiment), an electronegativity scale is obtained displaying (1) a monotonic decrease of χ when going down the periodic table, (2) top values not for the noble gases but for the halogens, as opposed to most (extrapolation) procedures of existing scales, invariably placing the noble gases on top, and (3) noble gases having electronegativities close to the chalcogens. In the accompanying hardness scale (hardly, if ever, discussed in the literature) the noble gases turn out to be by far the farthest the hardest elements, again with a continuous decrease with increasing Z. Combining χ value of the halogens and the noble gases the Ng(δ+)F(δ-) bond polarity emerging from ab initio calculations naturally emerges. In conclusion, the chemistry of the noble gases is for a large part determined by their extreme hardness, equivalent to a high resistance to change in its electronic population coupled to their high electronegativity.

Carbon dioxide solubility in aqueous solutions of sodium chloride at geological conditions: Experimental results at 323.15, 373.15, and 423.15 K and 150 bar and modeling up to 573.15 K and 2000 bar

NASA Astrophysics Data System (ADS)

Zhao, Haining; Fedkin, Mark V.; Dilmore, Robert M.; Lvov, Serguei N.

2015-01-01

A new experimental system was designed to measure the solubility of CO2 at pressures and temperatures (150 bar, 323.15-423.15 K) relevant to geologic CO2 sequestration. At 150 bar, new CO2 solubility data in the aqueous phase were obtained at 323.15, 373.15, and 423.15 K from 0 to 6 mol kg-1 NaCl(aq) for the CO2-NaCl-H2O system. A γ - φ (activity coefficient - fugacity coefficient) type thermodynamic model is presented for the calculation of both the solubility of CO2 in the aqueous phase and the solubility of H2O in the CO2-rich phase for the CO2-NaCl-H2O system. Validation of the model calculations against literature data and other models (MZLL2013, AD2010, SP2010, DS2006, and OLI) show that the proposed model is capable of predicting the solubility of CO2 in the aqueous phase for the CO2-H2O and CO2-NaCl-H2O systems with a high degree of accuracy (AAD <3.9%) at temperatures from 273.15 to 573.15 K and pressures up to 2000 bar. A comparison of modeling results with experimental values revealed a pressure-bounded "transition zone" in which the CO2 solubility decreases to a minimum then increases as the temperature increases. CO2 solubility is not a monotonic function of temperature in the transition zone but outside of that transition zone, the CO2 solubility is decrease or increase monotonically in response to increased temperature. A link of web-based CO2 solubility computational tool can be provided by sending a message to Haining Zhao at hzz5047@gmail.com.

Size Effect on the Mechanical Properties of CF Winding Composite

NASA Astrophysics Data System (ADS)

Cui, Yuqing; Yin, Zhongwei

2017-12-01

Mechanical properties of filament winding composites are usually tested by NOL ring samples. Few people have studied the size effect of winding composite samples on the testing result of mechanical property. In this research, winding composite thickness, diameter, and geometry of NOL ring samples were prepared to investigate the size effect on the mechanical strength of carbon fiber (CF) winding composite. The CF T700, T1000, M40, and M50 were adopted for the winding composite, while the matrix was epoxy resin. Test results show that the tensile strength and ILSS of composites decreases monotonically with an increase of thickness from 1 mm to 4 mm. The mechanical strength of composite samples increases monotonically with the increase in diameter from 100 mm to 189 mm. The mechanical strength of composite samples with two flat sides are higher than those of cyclic annular samples.

Effect of Reinforcer Magnitude on Performance Maintained by Progressive-Ratio Schedules

PubMed Central

Rickard, J.F; Body, S; Zhang, Z; Bradshaw, C.M; Szabadi, E

2009-01-01

This experiment examined the relationship between reinforcer magnitude and quantitative measures of performance on progressive-ratio schedules. Fifteen rats were trained under a progressive-ratio schedule in seven phases of the experiment in which the volume of a 0.6-M sucrose solution reinforcer was varied within the range 6–300 µl. Overall response rates in successive ratios conformed to a bitonic equation derived from Killeen's (1994) Mathematical Principles of Reinforcement. The “specific activation” parameter, a, which is presumed to reflect the incentive value of the reinforcer, was a monotonically increasing function of reinforcer volume; the “response time” parameter, δ, which defines the minimum response time, increased as a function of reinforcer volume; the “currency” parameter, β, which is presumed to reflect the coupling of responses to the reinforcer, declined as a function of volume. Running response rate (response rate calculated after exclusion of the postreinforcement pause) decayed monotonically as a function of ratio size; the index of curvature of this function increased as a function of reinforcer volume. Postreinforcement pause increased as a function of ratio size. Estimates of a derived from overall response rates and postreinforcement pauses showed a modest positive correlation across conditions and between animals. Implications of the results for the quantification of reinforcer value and for the use of progressive-ratio schedules in behavioral neuroscience are discussed. PMID:19230513

Effect of reinforcer magnitude on performance maintained by progressive-ratio schedules.

PubMed

Rickard, J F; Body, S; Zhang, Z; Bradshaw, C M; Szabadi, E

2009-01-01

This experiment examined the relationship between reinforcer magnitude and quantitative measures of performance on progressive-ratio schedules. Fifteen rats were trained under a progressive-ratio schedule in seven phases of the experiment in which the volume of a 0.6-M sucrose solution reinforcer was varied within the range 6-300 microl. Overall response rates in successive ratios conformed to a bitonic equation derived from Killeen's (1994) Mathematical Principles of Reinforcement. The "specific activation" parameter, a, which is presumed to reflect the incentive value of the reinforcer, was a monotonically increasing function of reinforcer volume; the "response time" parameter, delta, which defines the minimum response time, increased as a function of reinforcer volume; the "currency" parameter, beta, which is presumed to reflect the coupling of responses to the reinforcer, declined as a function of volume. Running response rate (response rate calculated after exclusion of the postreinforcement pause) decayed monotonically as a function of ratio size; the index of curvature of this function increased as a function of reinforcer volume. Postreinforcement pause increased as a function of ratio size. Estimates of a derived from overall response rates and postreinforcement pauses showed a modest positive correlation across conditions and between animals. Implications of the results for the quantification of reinforcer value and for the use of progressive-ratio schedules in behavioral neuroscience are discussed.

Exact conditions on the temperature dependence of density functionals

DOE PAGES

Burke, K.; Smith, J. C.; Grabowski, P. E.; ...

2016-05-15

Universal exact conditions guided the construction of most ground-state density functional approximations in use today. Here, we derive the relation between the entropy and Mermin free energy density functionals for thermal density functional theory. Both the entropy and sum of kinetic and electron-electron repulsion functionals are shown to be monotonically increasing with temperature, while the Mermin functional is concave downwards. Analogous relations are found for both exchange and correlation. The importance of these conditions is illustrated in two extremes: the Hubbard dimer and the uniform gas.

Non-monotonic course of protein solubility in aqueous polymer-salt solutions can be modeled using the sol-mxDLVO model.

PubMed

Herhut, Marcel; Brandenbusch, Christoph; Sadowski, Gabriele

2016-02-01

Protein purification is often performed using cost-intensive chromatographic steps. To discover economic alternatives (e.g., crystallization), knowledge on protein solubility as a function of temperature, pH, and additives in solution as well as their concentration is required. State-of-the-art models for predicting protein solubility almost exclusively consider aqueous salt systems, whereas "salting-in" and "salting-out" effects induced by the presence of an additional polymer are not considered. Thus, we developed the sol-mxDLVO model. Using this newly developed model, protein solubility in the presence of one salt and one polymer, especially the non-monotonic course of protein solubility, could be predicted. Systems considered included salts (NaCl, Na-p-Ts, (NH(4))(2) SO(4)) and the polymer polyethylene glycol (MW: 2000 g/mol, 12000 g/mol) and proteins lysozyme from chicken egg white (pH 4 to 5.5) and D-xylose ketol-isomerase (pH 7) at 298.15 K. The results show that by using the sol-mxDLVO model, protein solubility in polymer-salt solutions can be modeled in good agreement with the experimental data for both proteins considered. The sol-mxDLVO model can describe the non-monotonic course of protein solubility as a function of polymer concentration and salt concentration, previously not covered by state-of-the-art models. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Control of electronic transport in graphene by electromagnetic dressing

PubMed Central

Kristinsson, K.; Kibis, O. V.; Morina, S.; Shelykh, I. A.

2016-01-01

We demonstrated theoretically that the renormalization of the electron energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) electronic transport in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control electronic properties of graphene with light. PMID:26838371

The effect of dropout on the efficiency of D-optimal designs of linear mixed models.

PubMed

Ortega-Azurduy, S A; Tan, F E S; Berger, M P F

2008-06-30

Dropout is often encountered in longitudinal data. Optimal designs will usually not remain optimal in the presence of dropout. In this paper, we study D-optimal designs for linear mixed models where dropout is encountered. Moreover, we estimate the efficiency loss in cases where a D-optimal design for complete data is chosen instead of that for data with dropout. Two types of monotonically decreasing response probability functions are investigated to describe dropout. Our results show that the location of D-optimal design points for the dropout case will shift with respect to that for the complete and uncorrelated data case. Owing to this shift, the information collected at the D-optimal design points for the complete data case does not correspond to the smallest variance. We show that the size of the displacement of the time points depends on the linear mixed model and that the efficiency loss is moderate.

Growth of Ni nanoclusters on irradiated graphene: a molecular dynamics study.

PubMed

Valencia, F J; Hernandez-Vazquez, E E; Bringa, E M; Moran-Lopez, J L; Rogan, J; Gonzalez, R I; Munoz, F

2018-04-23

We studied the soft landing of Ni atoms on a previously damaged graphene sheet by means of molecular dynamics simulations. We found a monotonic decrease of the cluster frequency as a function of its size, but few big clusters comprise an appreciable fraction of the total number of Ni atoms. The aggregation of Ni atoms is also modeled by means of a simple phenomenological model. The results are in clear contrast with the case of hard or energetic landing of metal atoms, where there is a tendency to form mono-disperse metal clusters. This behavior is attributed to the high diffusion of unattached Ni atoms, together with vacancies acting as capture centers. The findings of this work show that a simple study of the energetics of the system is not enough in the soft landing regime, where it is unavoidable to also consider the growth process of metal clusters.

Not even wrong: A philosophical, historical and ultimately a scientific inquiry into the Schmidt Law

NASA Astrophysics Data System (ADS)

Madore, Barry F.; Carlson, Erika K.

2017-03-01

We introduce a novel approach to interpreting the well-known spatial correlation of gas densities with on-going star formation. Treated as a closed-loop process involving two physically distinct phases the data can be subdivided into regions that are active and those that are quiescent. The active regions can be distinguished by the presence of high-mass, short-lived, but recently-formed OB stars; the quiescent regions are marked by an absence of these stars and they are considered to be recovering from the last star-formation event and are re-collapsing. The relative (areal) frequencies of those two phases are directly proportional to the relative timescales. For four Local Group galaxies, NGC 6822, the Large & Small Magellanic Clouds, and M33, the cloud assembly/collapse timescales are all found to be monotonically decreasing power-law functions of density, with as yet to be explained differences.

Anomalous and non-Gaussian diffusion in Hertzian spheres

NASA Astrophysics Data System (ADS)

Ouyang, Wenze; Sun, Bin; Sun, Zhiwei; Xu, Shenghua

2018-09-01

By means of molecular dynamics simulations, we study the non-Gaussian diffusion in the fluid of Hertzian spheres. The time dependent non-Gaussian parameter, as an indicator of the dynamic heterogeneity, is increased with the increasing of temperature. When the temperature is high enough, the dynamic heterogeneity becomes very significant, and it seems counterintuitive that the maximum of non-Gaussian parameter and the position of its peak decrease monotonically with the increasing of density. By fitting the curves of self intermediate scattering function, we find that the character relaxation time τα is surprisingly not coupled with the time τmax where the non-Gaussian parameter reaches to a maximum. The intriguing features of non-Gaussian diffusion at high enough temperatures can be associated with the weakly correlated mean-field behavior of Hertzian spheres. Especially the time τmax is nearly inversely proportional to the density at extremely high temperatures.

Thunderstorms and ground-based radio noise as observed by radio astronomy Explorer 1

NASA Technical Reports Server (NTRS)

Caruso, J. A.; Herman, J. R.

1973-01-01

Radio Astronomy Explorer (RAE) data were analyzed to determine the frequency dependence of HF terrestrial radio noise power. RAE observations of individual thunderstorms, mid-ocean areas, and specific geographic regions for which concommitant ground based measurements are available indicate that noise power is a monotonically decreasing function of frequency which conforms to expectations over the geographic locations and time periods investigated. In all cases investigated, active thunderstorm regions emit slightly higher power as contrasted to RAE observations of the region during meteorologically quiet periods. Noise levels are some 15 db higher than predicted values over mid-ocean, while in locations where ground based measurements are available a maximum deviation of 5 db occurs. Worldwide contour mapping of the noise power at 6000 km for five individual months and four observing frequencies, examples of which are given, indicate high noise levels over continental land masses with corresponding lower levels over ocean regions.

Prediction of human errors by maladaptive changes in event-related brain networks.

PubMed

Eichele, Tom; Debener, Stefan; Calhoun, Vince D; Specht, Karsten; Engel, Andreas K; Hugdahl, Kenneth; von Cramon, D Yves; Ullsperger, Markus

2008-04-22

Humans engaged in monotonous tasks are susceptible to occasional errors that may lead to serious consequences, but little is known about brain activity patterns preceding errors. Using functional MRI and applying independent component analysis followed by deconvolution of hemodynamic responses, we studied error preceding brain activity on a trial-by-trial basis. We found a set of brain regions in which the temporal evolution of activation predicted performance errors. These maladaptive brain activity changes started to evolve approximately 30 sec before the error. In particular, a coincident decrease of deactivation in default mode regions of the brain, together with a decline of activation in regions associated with maintaining task effort, raised the probability of future errors. Our findings provide insights into the brain network dynamics preceding human performance errors and suggest that monitoring of the identified precursor states may help in avoiding human errors in critical real-world situations.

Prediction of human errors by maladaptive changes in event-related brain networks

PubMed Central

Eichele, Tom; Debener, Stefan; Calhoun, Vince D.; Specht, Karsten; Engel, Andreas K.; Hugdahl, Kenneth; von Cramon, D. Yves; Ullsperger, Markus

2008-01-01

Humans engaged in monotonous tasks are susceptible to occasional errors that may lead to serious consequences, but little is known about brain activity patterns preceding errors. Using functional MRI and applying independent component analysis followed by deconvolution of hemodynamic responses, we studied error preceding brain activity on a trial-by-trial basis. We found a set of brain regions in which the temporal evolution of activation predicted performance errors. These maladaptive brain activity changes started to evolve ≈30 sec before the error. In particular, a coincident decrease of deactivation in default mode regions of the brain, together with a decline of activation in regions associated with maintaining task effort, raised the probability of future errors. Our findings provide insights into the brain network dynamics preceding human performance errors and suggest that monitoring of the identified precursor states may help in avoiding human errors in critical real-world situations. PMID:18427123

Structure and optical band gaps of (Ba,Sr)SnO{sub 3} films grown by molecular beam epitaxy

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

Schumann, Timo; Raghavan, Santosh; Ahadi, Kaveh

2016-09-15

Epitaxial growth of (Ba{sub x}Sr{sub 1−x})SnO{sub 3} films with 0 ≤ x ≤ 1 using molecular beam epitaxy is reported. It is shown that SrSnO{sub 3} films can be grown coherently strained on closely lattice and symmetry matched PrScO{sub 3} substrates. The evolution of the optical band gap as a function of composition is determined by spectroscopic ellipsometry. The direct band gap monotonously decreases with x from to 4.46 eV (x = 0) to 3.36 eV (x = 1). A large Burnstein-Moss shift is observed with La-doping of BaSnO{sub 3} films. The shift corresponds approximately to the increase in Fermi level and is consistent with the low conduction band mass.

Control of electronic transport in graphene by electromagnetic dressing.

PubMed

Kristinsson, K; Kibis, O V; Morina, S; Shelykh, I A

2016-02-03

We demonstrated theoretically that the renormalization of the electron energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) electronic transport in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control electronic properties of graphene with light.

Optical, compositional and structural properties of pulsed laser deposited nitrogen-doped Titanium-dioxide

NASA Astrophysics Data System (ADS)

Farkas, B.; Heszler, P.; Budai, J.; Oszkó, A.; Ottosson, M.; Geretovszky, Zs.

2018-03-01

N-doped TiO2 thin films were prepared using pulsed laser deposition by ablating metallic Ti target with pulses of 248 nm wavelength, at 330 °C substrate temperature in reactive atmospheres of N2/O2 gas mixtures. These films were characterized by spectroscopic ellipsometry, X-ray photoelectron spectroscopy and X-ray diffraction. Optical properties are presented as a function of the N2 content in the processing gas mixture and correlated to nitrogen incorporation into the deposited layers. The optical band gap values decreased with increasing N concentration in the films, while a monotonically increasing tendency and a maximum can be observed in case of extinction coefficient and refractive index, respectively. It is also shown that the amount of substitutional N can be increased up to 7.7 at.%, but the higher dopant concentration inhibits the crystallization of the samples.

On energetic prerequisites of attracting electrons

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

Sundholm, Dage

The internal reorganization energy and the zero-point vibrational energy (ZPE) of fractionally charged molecules embedded in molecular materials are discussed. The theory for isolated open quantum systems is taken as the starting point. It is shown that for isolated molecules the internal reorganization-energy function and its slope, i.e., the chemical potential of an open molecular system are monotonically decreasing functions with respect to increasing amount of negative excess charge (q) in the range of q = [0, 1]. Calculations of the ZPE for fractionally charged molecules show that the ZPE may have a minimum for fractional occupation. The calculations showmore » that the internal reorganization energy and changes in the ZPE are of the same order of magnitude with different behavior as a function of the excess charge. The sum of the contributions might favor molecules with fractional occupation of the molecular units and partial delocalization of the excess electrons in solid-state materials also when considering Coulomb repulsion between the excess electrons. The fractional electrons are then coherently distributed on many molecules of the solid-state material forming a condensate of attracting electrons, which is crucial for the superconducting state.« less

Prior-knowledge-based feedforward network simulation of true boiling point curve of crude oil.

PubMed

Chen, C W; Chen, D Z

2001-11-01

Theoretical results and practical experience indicate that feedforward networks can approximate a wide class of functional relationships very well. This property is exploited in modeling chemical processes. Given finite and noisy training data, it is important to encode the prior knowledge in neural networks to improve the fit precision and the prediction ability of the model. In this paper, as to the three-layer feedforward networks and the monotonic constraint, the unconstrained method, Joerding's penalty function method, the interpolation method, and the constrained optimization method are analyzed first. Then two novel methods, the exponential weight method and the adaptive method, are proposed. These methods are applied in simulating the true boiling point curve of a crude oil with the condition of increasing monotonicity. The simulation experimental results show that the network models trained by the novel methods are good at approximating the actual process. Finally, all these methods are discussed and compared with each other.

Community maturity, species saturation and the variant diversity- productivity relationships in grasslands

USGS Publications Warehouse

Guo, Q.; Shaffer, T.; Buhl, T.

2006-01-01

Detailed knowledge of the relationship between plant diversity and productivity is critical for advancing our understanding of ecosystem functioning and for achieving success in habitat restoration efforts. However, effects and interactions of diversity, succession and biotic invasions on productivity remain elusive. We studied newly established communities in relation to preexisting homogeneous vegetation invaded by exotic plants in the northern Great Plains, USA, at four study sites for 3 years. We observed variant diversity-productivity relationships for the seeded communities (generally positive monotonic at three sites and non-monotonic at the other site) but no relationships for the resident community or the seeded and resident communities combined at all sites and all years. Community richness was enhanced by seeding additional species but productivity was not. The optimal diversity (as indicated by maximum productivity) changed among sites and as the community developed. The findings shed new light on ecosystem functioning of biodiversity under different conditions and have important implications for restoration. ?? 2006 Blackwell Publishing Ltd/CNRS.

Negotiating on location, timing, duration, and participant in agent-mediated joint activity-travel scheduling

NASA Astrophysics Data System (ADS)

Ma, Huiye; Ronald, Nicole; Arentze, Theo A.; Timmermans, Harry J. P.

2013-10-01

Agent-based simulation has become an important modeling approach in activity-travel analysis. Social activities account for a large amount of travel and have an important effect on activity-travel scheduling. Participants in joint activities usually have various options regarding location, participants, and timing and take different approaches to make their decisions. In this context, joint activity participation requires negotiation among agents involved, so that conflicts among the agents can be addressed. Existing mechanisms do not fully provide a solution when utility functions of agents are nonlinear and non-monotonic. Considering activity-travel scheduling in time and space as an application, we propose a novel negotiation approach, which takes into account these properties, such as continuous and discrete issues, and nonlinear and non-monotonic utility functions, by defining a concession strategy and a search mechanism. The results of experiments show that agents having these properties can negotiate efficiently. Furthermore, the negotiation procedure affects individuals’ choices of location, timing, duration, and participants.

Quasi-Static Viscoelasticity Loading Measurements of an Aircraft Tire

NASA Technical Reports Server (NTRS)

Mason, Angela J.; Tanner, John A.; Johnson, Arthur R.

1997-01-01

Stair-step loading, cyclic loading, and long-term relaxation tests were performed on an aircraft tire to observe the quasi-static viscoelastic response of the tire. The data indicate that the tire continues to respond viscoelastically even after it has been softened by deformation. Load relaxation data from the stair-step test at the 15,000-lb loading was fit to a monotonically decreasing Prony series.

Thermodynamic Properties of a Double Ring-Shaped Quantum Dot at Low and High Temperatures

NASA Astrophysics Data System (ADS)

Khordad, R.; Sedehi, H. R. Rastegar

2018-02-01

In this work, we study thermodynamic properties of a GaAs double ring-shaped quantum dot under external magnetic and electric fields. To this end, we first solve the Schrödinger equation and obtain the energy levels and wave functions, analytically. Then, we calculate the entropy, heat capacity, average energy and magnetic susceptibility of the quantum dot in the presence of a magnetic field using the canonical ensemble approach. According to the results, it is found that the entropy is an increasing function of temperature. At low temperatures, the entropy increases monotonically with raising the temperature for all values of the magnetic fields and it is independent of the magnetic field. But, the entropy depends on the magnetic field at high temperatures. The entropy also decreases with increasing the magnetic field. The heat capacity and magnetic susceptibility show a peak structure. The heat capacity reduces with increasing the magnetic field at low temperatures. The magnetic susceptibility shows a transition between diamagnetic and paramagnetic below for T<4 K. The transition temperature depends on the magnetic field.

Viscoplasticity based on overstress with a differential growth law for the equilibrium stress

NASA Technical Reports Server (NTRS)

Krempl, E.; Mcmahon, J. J.; Yao, D.

1985-01-01

Two coupled, nonlinear differential equations are proposed for the modeling of the elastic and rate (time) dependent inelastic behavior of structural metals in the absence of recovery and aging. The structure of the model is close to the unified theories but contains essential differences. It is shown that the model reproduces almost elastic regions upon initial loading and in the unloading regions of the hysteresis loop. Under loading, unloading and reloading in strain control the model simulated the experimentally observed sharp transition from nearly elastic to inelastic behavior. When a formulation akin to existing unified theories is adopted the almost elastic regions reduce the points and the transition upon reloading is very gradual. For different formulations the behavior under sudden in(de)creases of the strain rate by two orders of magnitude is simulated by numerical experiments and differences are noted. The model represents cyclically neutral behavior and contains three constants and two positive, decreasing functions. The determination of constants and functions from monotonic loading with strain rate changes and relaxation periods is described.

Investigation of runaway electron dissipation in DIII-D using a gamma ray imager

NASA Astrophysics Data System (ADS)

Lvovskiy, A.; Paz-Soldan, C.; Eidietis, N.; Pace, D.; Taussig, D.

2017-10-01

We report the findings of a novel gamma ray imager (GRI) to study runaway electron (RE) dissipation in the quiescent regime on the DIII-D tokamak. The GRI measures the bremsstrahlung emission by RE providing information on RE energy spectrum and distribution across a poloidal cross-section. It consists of a lead pinhole camera illuminating a matrix of BGO detectors placed in the DIII-D mid-plane. The number of detectors was recently doubled to provide better spatial resolution and additional detector shielding was implemented to reduce un-collimated gamma flux and increase single-to-noise ratio. Under varying loop voltage, toroidal magnetic field and plasma density, a non-monotonic RE distribution function has been revealed as a result of the interplay between electric field, synchrotron radiation and collisional damping. A fraction of the high-energy RE population grows forming a bump at the RE distribution function while synchrotron radiation decreases. A possible destabilizing effect of Parail-Pogutse instability on the RE population will be also discussed. Work supported by the US DOE under DE-FC02-04ER54698.

The pH-influenced PET processes between pyronine and different heterocycles.

PubMed

Yang, Ling; Niu, Jin-Yun; Sun, Ru; Xu, Yu-Jie; Ge, Jian-Feng

2017-10-11

The OFF-ON and ON-OFF type pH probes based on rosamine were designed by using the relative electron densities between pyronine and various linked heterocycles. Probe 1a with an indole-pyronine skeleton gave an OFF-ON pH response (pK a = 1.41) with decreasing pH, and the relative fluorescence intensity increased 15-fold, while probe 1b with an imidazole-pyronine skeleton did not give an ON-OFF response to different pH values. When pyronine was connected with a quinolinyl group, i.e., probes 1c-d, the red emission (around 575-800 nm) gave a monotonous ON-OFF pH response (pK a = 3.26 and 2.62, respectively) with decreasing pH. The relative fluorescence intensities decreased 263- and 46-fold, respectively. Changes in the electron donating abilities of the nitrogen containing heterocycles were used to explain variations in PET processes within the probes, and their pH-dependent PET mechanisms were verified using time-dependent density functional theory calculations. Confocal fluorescence imaging was also used to evaluate the potential biomedical application of probes 1a-d. Ultimately, probe 1d with an appropriate pK a value and good biocompatibility showed lysosome targeting ability.

Development of Apparatus for Microgravity Experiments on Evaporation and Combustion of Palm Methyl Ester Droplet in High-Pressure Environments

NASA Astrophysics Data System (ADS)

Suzuki, Masato; Nomura, Hiroshi; Hashimoto, Nozomu

New apparatus for microgravity experiments was developed in order to obtain fundamental data of single droplet evaporation and combustion of palm methyl ester (PME) for understanding PME spray combustion in internal combustion engines. n-hexadecane droplet combustion and evaporation experiments were also performed to obtain single-component fuel data. Combustion experiments were performed at atmospheric pressure and room temperature. For droplet evaporation experiments, ambient temperature and pressure were varied from 473 to 873 K and 0.10 to 4.0 MPa, respectively. Microgravity conditions were employed for evaporation experiments to prevent natural convection. Droplet diameter history of a burning PME droplet is similar to that of n-hexadecane. Droplet diameter history of an evaporating PME droplet is different from that of n-hexadecane at low ambient temperatures. In the latest stage of PME droplet evaporation, temporal evaporation constant decreases remarkably. At ambient temperatures sufficiently above the boiling temperature of PME components, droplet diameter history of PME and n-hexadecane are similar to each other. Corrected evaporation lifetime τ of PME at 873 K as a function of ambient pressure was obtained at normal and microgravity. At normal gravity, τ monotonically decreases with ambient pressure. On the other hand, at microgravity, τ increases with ambient pressure, and then decreases.

Dynamic Balanced Reach: A Temporal and Spectral Analysis Across Increasing Performance Demands

PubMed Central

Barton, Joseph E.; Graci, Valentina; Hafer-Macko, Charlene; Sorkin, John D.; F. Macko, Richard

2016-01-01

Standing balanced reach is a fundamental task involved in many activities of daily living that has not been well analyzed quantitatively to assess and characterize the multisegmental nature of the body's movements. We developed a dynamic balanced reach test (BRT) to analyze performance in this activity; in which a standing subject is required to maintain balance while reaching and pointing to a target disk moving across a large projection screen according to a sum-of-sines function. This tracking and balance task is made progressively more difficult by increasing the disk's overall excursion amplitude. Using kinematic and ground reaction force data from 32 young healthy subjects, we investigated how the motions of the tracking finger and whole-body center of mass (CoM) varied in response to the motion of the disk across five overall disk excursion amplitudes. Group representative performance statistics for the cohort revealed a monotonically increasing root mean squared (RMS) tracking error (RMSE) and RMS deviation (RMSD) between whole-body CoM (projected onto the ground plane) and the center of the base of support (BoS) with increasing amplitude (p < 0.03). Tracking and CoM response delays remained constant, however, at 0.5 s and 1.0 s, respectively. We also performed detailed spectral analyses of group-representative response data for each of the five overall excursion amplitudes. We derived empirical and analytical transfer functions between the motion of the disk and that of the tracking finger and CoM, computed tracking and CoM responses to a step input, and RMSE and RMSD as functions of disk frequency. We found that for frequencies less than 1.0 Hz, RMSE generally decreased, while RMSE normalized to disk motion amplitude generally increased. RMSD, on the other hand, decreased monotonically. These findings quantitatively characterize the amplitude- and frequency-dependent nature of young healthy tracking and balance in this task. The BRT is not subject to floor or ceiling effects, overcoming an important deficiency associated with most research and clinical instruments used to assess balance. This makes a comprehensive quantification of young healthy balance performance possible. The results of such analyses could be used in work space design and in fall-prevention instructional materials, for both the home and work place. Young healthy performance represents “exemplar” performance and can also be used as a reference against which to compare the performance of aging and other clinical populations at risk for falling. PMID:27551977

Sugeno Fuzzy Integral as a Basis for the Interpretation of Flexible Queries Involving Monotonic Aggregates.

ERIC Educational Resources Information Center

Bosc, P.; Lietard, L.; Pivert, O.

2003-01-01

Considers flexible querying of relational databases. Highlights include SQL languages and basic aggregate operators; Sugeno's fuzzy integral; evaluation examples; and how and under what conditions other aggregate functions could be applied to fuzzy sets in a flexible query. (Author/LRW)

Monotonic and Nonmonotonic Lag Effects in Paired-Associate and Recognition Memory Paradigms

ERIC Educational Resources Information Center

Glenberg, Arthur M.

1976-01-01

Three experiments are reported investigating the relationship between response recall and the spacing of repetitions as a function of the retention interval. The results of the experiments support the theory which emphasizes the nature of the cues available for retrieval. (Author/RM)

Using polynomials to simplify fixed pattern noise and photometric correction of logarithmic CMOS image sensors.

PubMed

Li, Jing; Mahmoodi, Alireza; Joseph, Dileepan

2015-10-16

An important class of complementary metal-oxide-semiconductor (CMOS) image sensors are those where pixel responses are monotonic nonlinear functions of light stimuli. This class includes various logarithmic architectures, which are easily capable of wide dynamic range imaging, at video rates, but which are vulnerable to image quality issues. To minimize fixed pattern noise (FPN) and maximize photometric accuracy, pixel responses must be calibrated and corrected due to mismatch and process variation during fabrication. Unlike literature approaches, which employ circuit-based models of varying complexity, this paper introduces a novel approach based on low-degree polynomials. Although each pixel may have a highly nonlinear response, an approximately-linear FPN calibration is possible by exploiting the monotonic nature of imaging. Moreover, FPN correction requires only arithmetic, and an optimal fixed-point implementation is readily derived, subject to a user-specified number of bits per pixel. Using a monotonic spline, involving cubic polynomials, photometric calibration is also possible without a circuit-based model, and fixed-point photometric correction requires only a look-up table. The approach is experimentally validated with a logarithmic CMOS image sensor and is compared to a leading approach from the literature. The novel approach proves effective and efficient.

Games of age-dependent prevention of chronic infections by social distancing.

PubMed

Reluga, Timothy C; Li, Jing

2013-06-01

Epidemiological games combine epidemic modelling with game theory to assess strategic choices in response to risks from infectious diseases. In most epidemiological games studied thus-far, the strategies of an individual are represented with a single choice parameter. There are many natural situations where strategies can not be represented by a single dimension, including situations where individuals can change their behavior as they age. To better understand how age-dependent variations in behavior can help individuals deal with infection risks, we study an epidemiological game in an SI model with two life-history stages where social distancing behaviors that reduce exposure rates are age-dependent. When considering a special case of the general model, we show that there is a unique Nash equilibrium when the infection pressure is a monotone function of aggregate exposure rates, but non-monotone effects can appear even in our special case. The non-monotone effects sometimes result in three Nash equilibria, two of which have local invasion potential simultaneously. Returning to a general case, we also describe a game with continuous age-structure using partial-differential equations, numerically identify some Nash equilibria, and conjecture about uniqueness.

Global stability analysis of two-strain epidemic model with bilinear and non-monotone incidence rates

NASA Astrophysics Data System (ADS)

Baba, Isa Abdullahi; Hincal, Evren

2017-05-01

In this article we studied an epidemic model consisting of two strains with different types of incidence rates; bilinear and non-monotone. The model consists of four equilibrium points: disease-free equilibrium, endemic with respect to strain 1, endemic with respect to strain 2, and endemic with respect to both strains. The global stability analysis of the equilibrium points was carried out through the use of Lyapunov functions. Two basic reproduction ratios R 1 0 and R 2 0 are found, and we have shown that if both are less than one, the disease dies out, and if both are greater than one epidemic occurs. Furthermore, epidemics occur with respect to any strain with a basic reproduction ratio greater than one and disease dies out with respect to any strain with a basic reproduction ratio less than one. It was also shown that any strain with highest basic reproduction ratio will automatically outperform the other strain, thereby eliminating it. Numerical simulations were carried out to support the analytic result and to show the effect of the parameter k in the non-monotone incidence rate, which describes the psychological effect of general public towards infection.

The acoustical bright spot and mislocalization of tones by human listeners.

PubMed

Macaulay, Eric J; Hartmann, William M; Rakerd, Brad

2010-03-01

Listeners attempted to localize 1500-Hz sine tones presented in free field from a loudspeaker array, spanning azimuths from 0 degrees (straight ahead) to 90 degrees (extreme right). During this task, the tone levels and phases were measured in the listeners' ear canals. Because of the acoustical bright spot, measured interaural level differences (ILD) were non-monotonic functions of azimuth with a maximum near 55 degrees . In a source-identification task, listeners' localization decisions closely tracked the non-monotonic ILD, and thus became inaccurate at large azimuths. When listeners received training and feedback, their accuracy improved only slightly. In an azimuth-discrimination task, listeners decided whether a first sound was to the left or to the right of a second. The discrimination results also reflected the confusion caused by the non-monotonic ILD, and they could be predicted approximately by a listener's identification results. When the sine tones were amplitude modulated or replaced by narrow bands of noise, interaural time difference (ITD) cues greatly reduced the confusion for most listeners, but not for all. Recognizing the important role of the bright spot requires a reevaluation of the transition between the low-frequency region for localization (mainly ITD) and the high-frequency region (mainly ILD).

Impact of the infectious period on epidemics

NASA Astrophysics Data System (ADS)

Wilkinson, Robert R.; Sharkey, Kieran J.

2018-05-01

The duration of the infectious period is a crucial determinant of the ability of an infectious disease to spread. We consider an epidemic model that is network based and non-Markovian, containing classic Kermack-McKendrick, pairwise, message passing, and spatial models as special cases. For this model, we prove a monotonic relationship between the variability of the infectious period (with fixed mean) and the probability that the infection will reach any given subset of the population by any given time. For certain families of distributions, this result implies that epidemic severity is decreasing with respect to the variance of the infectious period. The striking importance of this relationship is demonstrated numerically. We then prove, with a fixed basic reproductive ratio (R0), a monotonic relationship between the variability of the posterior transmission probability (which is a function of the infectious period) and the probability that the infection will reach any given subset of the population by any given time. Thus again, even when R0 is fixed, variability of the infectious period tends to dampen the epidemic. Numerical results illustrate this but indicate the relationship is weaker. We then show how our results apply to message passing, pairwise, and Kermack-McKendrick epidemic models, even when they are not exactly consistent with the stochastic dynamics. For Poissonian contact processes, and arbitrarily distributed infectious periods, we demonstrate how systems of delay differential equations and ordinary differential equations can provide upper and lower bounds, respectively, for the probability that any given individual has been infected by any given time.

Current characteristics of λ-DNA molecules/polystyrene nanoparticles in TBE buffer solution through micro/nanofluidic capillaries under DC electric field

NASA Astrophysics Data System (ADS)

Duan, Yifei; Zhao, Wei; Xue, Jing; Sun, Dan; Wang, Kaige; Wang, Guiren; Li, Junjie; Bai, Jintao; Gu, Changzhi

2017-03-01

In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate single bio-molecules and analyze their characteristics. To accurately and flexibly control the movement of single-molecule within micro/nanofluidic channels which are the basic components of Lab-chips, the current signals in micro/nanocapillaries filled with solutions of DNA molecules or polystyrene (PS) nanoparticles are systematically studied. Experimental results indicate that the current response along the micro/nanocapillaries can be significantly influenced by the diameter of the capillaries and the pH value of the solutions. Specifically, when there is only a pure (TBE) solution, the electric conductance does not monotonically decrease with decreasing the diameter of the capillaries, but slightly increases with decreasing the capillary diameter. When λ-DNA molecules or PS nanoparticles are added into the TBE buffer, the size effect on the electric conductance of the solutions are quite different. Although in the former, the electric conductance behaves differently from that in the pure TBE solution and decreases with the decreasing diameter, in the latter, the change is similar to that in the pure TBE solution. Besides, an abnormal ‘falling’ of the electric conductance is observed in a capillary with diameter of 200 nm. The investigation will significantly enhance the understanding on the electric properties of the solutions of biomolecules and particles in micro/nanofluidics. This is especially helpful for designing functional Lab-chip devices.

Aging effects on functional auditory and visual processing using fMRI with variable sensory loading.

PubMed

Cliff, Michael; Joyce, Dan W; Lamar, Melissa; Dannhauser, Thomas; Tracy, Derek K; Shergill, Sukhwinder S

2013-05-01

Traditionally, studies investigating the functional implications of age-related structural brain alterations have focused on higher cognitive processes; by increasing stimulus load, these studies assess behavioral and neurophysiological performance. In order to understand age-related changes in these higher cognitive processes, it is crucial to examine changes in visual and auditory processes that are the gateways to higher cognitive functions. This study provides evidence for age-related functional decline in visual and auditory processing, and regional alterations in functional brain processing, using non-invasive neuroimaging. Using functional magnetic resonance imaging (fMRI), younger (n=11; mean age=31) and older (n=10; mean age=68) adults were imaged while observing flashing checkerboard images (passive visual stimuli) and hearing word lists (passive auditory stimuli) across varying stimuli presentation rates. Younger adults showed greater overall levels of temporal and occipital cortical activation than older adults for both auditory and visual stimuli. The relative change in activity as a function of stimulus presentation rate showed differences between young and older participants. In visual cortex, the older group showed a decrease in fMRI blood oxygen level dependent (BOLD) signal magnitude as stimulus frequency increased, whereas the younger group showed a linear increase. In auditory cortex, the younger group showed a relative increase as a function of word presentation rate, while older participants showed a relatively stable magnitude of fMRI BOLD response across all rates. When analyzing participants across all ages, only the auditory cortical activation showed a continuous, monotonically decreasing BOLD signal magnitude as a function of age. Our preliminary findings show an age-related decline in demand-related, passive early sensory processing. As stimulus demand increases, visual and auditory cortex do not show increases in activity in older compared to younger people. This may negatively impact on the fidelity of information available to higher cognitive processing. Such evidence may inform future studies focused on cognitive decline in aging. Copyright © 2012 Elsevier Ltd. All rights reserved.

The physical properties of Li-doped g-C{sub 3}N{sub 4} monolayer sheet investigated by the first-principles

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

Ruan, Linwei; Xu, Gengsheng; Gu, Lina

2015-06-15

Highlights: • Systematically research on Li-doped g-C{sub 3}N{sub 4} monolayer sheets by first-principles calculation. • Optimal dopant concentration for optical absorption is 7.12%. • Thermodynamics stability of the doped substrate g-C{sub 3}N{sub 4} decreased with Li dopant concentration increasing. • The values of work function Φ decreased monotonously with the increasing of Li dopant concentration. - Abstract: The geometric, electronic, optical properties, thermodynamic stability, and work function of Li-doped g-C{sub 3}N{sub 4} monolayer were investigated by the first-principles calculation. It was found that the Li atoms were preferentially substituted the open-hollow sites of g-C{sub 3}N{sub 4}. Interestingly, the “odd” numbermore » of Li doped g-C{sub 3}N{sub 4} showed metallic properties, while the “even” number of Li atoms widened the band gap of g-C{sub 3}N{sub 4}. The HOMO and LUMO distributions reveal that the active sites located at edge N and C atoms for both pristine and the Li-doped g-C{sub 3}N{sub 4}. In addition, thermodynamic analysis showed that the doped Li atoms reduced the thermodynamic stability of g-C{sub 3}N{sub 4} monolayer sheets.« less

The dependence of the modulation transfer function on the blocking layer thickness in amorphous selenium x-ray detectors

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

Hunter, David M.; Belev, Gueorgi; DeCrescenzo, Giovanni

2007-08-15

Blocking layers are used to reduce leakage current in amorphous selenium detectors. The effect of the thickness of the blocking layer on the presampling modulation transfer function (MTF) and on dark current was experimentally determined in prototype single-line CCD-based amorphous selenium (a-Se) x-ray detectors. The sampling pitch of the detectors evaluated was 25 {mu}m and the blocking layer thicknesses varied from 1 to 51 {mu}m. The blocking layers resided on the signal collection electrodes which, in this configuration, were used to collect electrons. The combined thickness of the blocking layer and a-Se bulk in each detector was {approx}200 {mu}m. Asmore » expected, the dark current increased monotonically as the thickness of the blocking layer was decreased. It was found that if the blocking layer thickness was small compared to the sampling pitch, it caused a negligible reduction in MTF. However, the MTF was observed to decrease dramatically at spatial frequencies near the Nyquist frequency as the blocking layer thickness approached or exceeded the electrode sampling pitch. This observed reduction in MTF is shown to be consistent with predictions of an electrostatic model wherein the image charge from the a-Se is trapped at a characteristic depth within the blocking layer, generally near the interface between the blocking layer and the a-Se bulk.« less

Annealing Effects on the Normal-State Resistive Properties of Underdoped Cuprates

NASA Astrophysics Data System (ADS)

Vovk, R. V.; Khadzhai, G. Ya.; Nazyrov, Z. F.; Kamchatnaya, S. N.; Feher, A.; Dobrovolskiy, O. V.

2018-05-01

The influence of room-temperature annealing on the parameters of the basal-plane electrical resistance of underdoped YBa_2Cu_3O_{7-δ } and HoBa_2Cu_3O_{7-δ } single crystals in the normal and superconducting states is investigated. The form of the derivatives dρ (T)/dT makes it possible to determine the onset temperature of the fluctuation conductivity and indicates a nonuniform distribution of the labile oxygen. Annealing has been revealed to lead to a monotonic decrease in the oxygen deficiency, that primarily manifests itself as a decrease in the residual resistance, an increase of T_c, and a decrease in the Debye temperature.

On Monotone Embedding in Information Geometry (Open Access)

DTIC Science & Technology

2015-06-25

the non-parametric ( infinite - dimensional ) setting, as well [4,6], with the α-connection structure cast in a more general way. Theorem 1 of [4] gives... the weighting function for taking the expectation of random variables in calculating the Riemannian metric (G = 1 reduces to F - geometry , with the ...is a trivial rewriting of the convex function f used by [2]. This paper will start in Section 1

Memory Effect Manifested by a Boson Peak in Metallic Glass.

PubMed

Luo, P; Li, Y Z; Bai, H Y; Wen, P; Wang, W H

2016-04-29

We explore the correlation between a boson peak and structural relaxation in a typical metallic glass. Consistent with enthalpy recovery, a boson peak shows a memory effect in an aging-and-scan procedure. Single-step isothermal aging produces a monotonic decrease of enthalpy and boson peak intensity; for double-step isothermal aging, both enthalpy and boson peak intensity experience, coincidently, an incipient increase to a maximum and a subsequent decrease toward the equilibrium state. Our results indicate a direct link between slow structural relaxation and fast boson peak dynamics, which presents a profound understanding of the two dynamic behaviors in glass.

Effect of Ge atoms on crystal structure and optoelectronic properties of hydrogenated Si-Ge films

NASA Astrophysics Data System (ADS)

Li, Tianwei; Zhang, Jianjun; Ma, Ying; Yu, Yunwu; Zhao, Ying

2017-07-01

Optoelectronic and structural properties of hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H) alloys prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) were investigated. When the Ge atoms were predominantly incorporated in amorphous matrix, the dark and photo-conductivity decreased due to the reduced crystalline volume fraction of the Si atoms (XSi-Si) and the increased Ge dangling bond density. The photosensitivity decreased monotonously with Ge incorporation under higher hydrogen dilution condition, which was attributed to the increase in both crystallization of Ge and the defect density.

Robust Decision Making in a Nonlinear World

ERIC Educational Resources Information Center

Dougherty, Michael R.; Thomas, Rick P.

2012-01-01

The authors propose a general modeling framework called the general monotone model (GeMM), which allows one to model psychological phenomena that manifest as nonlinear relations in behavior data without the need for making (overly) precise assumptions about functional form. Using both simulated and real data, the authors illustrate that GeMM…

Samejima Items in Multiple-Choice Tests: Identification and Implications

ERIC Educational Resources Information Center

Rahman, Nazia

2013-01-01

Samejima hypothesized that non-monotonically increasing item response functions (IRFs) of ability might occur for multiple-choice items (referred to here as "Samejima items") if low ability test takers with some, though incomplete, knowledge or skill are drawn to a particularly attractive distractor, while very low ability test takers…

Flocking and invariance of velocity angles.

PubMed

Liu, Le; Huang, Lihong; Wu, Jianhong

2016-04-01

Motsch and Tadmor considered an extended Cucker-Smale model to investigate the flocking behavior of self-organized systems of interacting species. In this extended model, a cone of the vision was introduced so that outside the cone the influence of one agent on the other is lost and hence the corresponding influence function takes the value zero. This creates a problem to apply the Motsch-Tadmor and Cucker-Smale method to prove the flocking property of the system. Here, we examine the variation of the velocity angles between two arbitrary agents, and obtain a monotonicity property for the maximum cone of velocity angles. This monotonicity permits us to utilize existing arguments to show the flocking property of the system under consideration, when the initial velocity angles satisfy some minor technical constraints.

The geomorphic evolution of the lunar surface.

NASA Technical Reports Server (NTRS)

Ronca, L. B.

1972-01-01

The solution of the function relating craters of the continuous degradation sequence with degree of erosion was defined as the geomorphic index of the area. Studies of the geomorphic index of stratigraphic surfaces show that areas covered by considerable ballistic sediments have a geomorphic index which is not a monotonic function of time. On the other hand, areas covered almost exclusively by mare flooding show an index which is a monotonic function of the age of the flooding. As each mare surface shows a considerable range in indices, it is concluded that maria are covered by surfaces formed through a considerable length of time. By using Apollo 11 and 12 radiometric ages it is suggested that the time of mare flooding lasted on the order of one billion years. The geomorphic index of highland surfaces shows a remarkable degree of order - i.e., the farther an area is inland from the mare shores, the higher will be the index. No explanation is given for this phenomenon, but it is suggested that lunar erosion is not just a localized phenomenon centered on the locus of an impact, but has lateral trends of regional dimensions.

n-dimensional isotropic Finch-Skea stars

NASA Astrophysics Data System (ADS)

Chilambwe, Brian; Hansraj, Sudan

2015-02-01

We study the impact of dimension on the physical properties of the Finch-Skea astrophysical model. It is shown that a positive definite, monotonically decreasing pressure and density are evident. A decrease in stellar radius emerges as the order of the dimension increases. This is accompanied by a corresponding increase in energy density. The model continues to display the necessary qualitative features inherent in the 4-dimensional Finch-Skea star and the conformity to the Walecka theory is preserved under dimensional increase. The causality condition is always satisfied for all dimensions considered resulting in the proposed models demonstrating a subluminal sound speed throughout the interior of the distribution. Moreover, the pressure and density decrease monotonically outwards from the centre and a pressure-free hypersurface exists demarcating the boundary of the perfect-fluid sphere. Since the study of the physical conditions is performed graphically, it is necessary to specify certain constants in the model. Reasonable values for such constants are arrived at on examining the behaviour of the model at the centre and demanding the satisfaction of all elementary conditions for physical plausibility. Finally two constants of integration are settled on matching of our solutions with the appropriate Schwarzschild-Tangherlini exterior metrics. Furthermore, the solution admits a barotropic equation of state despite the higher dimension. The compactification parameter as well as the density variation parameter are also computed. The models satisfy the weak, strong and dominant energy conditions in the interior of the stellar configuration.

A Decision Analysis Perspective on Multiple Response Robust Optimization

DTIC Science & Technology

2012-03-01

the utility function in question is monotonically increasing and is twice differentiable . If γ(y) = 0, the utility function is describing risk neutral...twice differentiable , the risk aversion function with respect to a single attribute, yi, i = 1, . . . , n, is given in Equation 2.9, γUyi = − U ′′yi U...UV (V (y1, y2)) and fol- lowing the chain rule of differentiation , Matheson and Abbas [31] show that the risk aversion with respect to a single

Influence of hydrostatic pressure on the switching time and switching coefficient of NiZnCo ferrites

NASA Astrophysics Data System (ADS)

Romanowski, S.; Goldberg, S.

1980-04-01

Results of the investigation of the effect of hydrostatic pressure on the pulse performance of NiZnCo ferrites with square hysteresis loop are given. It is stated that with increasing hydrostatic pressure, the threshold field strength increases, the switching coefficient value decreases, while the switching time value may increase monotonically or reach a maximum depending on the magnetizing field strength.

Four Eras of Study of College Student Suicide in the United States: 1920-2004

ERIC Educational Resources Information Center

Schwartz, Allan J.

2006-01-01

Studies of college student suicide can be grouped into the following 4 eras: 1920-1960, 1960-1980, 1980-1990, and 1990-2004. The suicide rate for students has declined monotonically across these 4 eras, from 13.4 to 8.0 to 7.5 and, most recently, to 6.5. The decreasing proportion of men in the student populations studied largely accounts for this…

Observation of quantum-memory-assisted entropic uncertainty relation under open systems, and its steering

NASA Astrophysics Data System (ADS)

Chen, Peng-Fei; Sun, Wen-Yang; Ming, Fei; Huang, Ai-Jun; Wang, Dong; Ye, Liu

2018-01-01

Quantum objects are susceptible to noise from their surrounding environments, interaction with which inevitably gives rise to quantum decoherence or dissipation effects. In this work, we examine how different types of local noise under an open system affect entropic uncertainty relations for two incompatible measurements. Explicitly, we observe the dynamics of the entropic uncertainty in the presence of quantum memory under two canonical categories of noisy environments: unital (phase flip) and nonunital (amplitude damping). Our study shows that the measurement uncertainty exhibits a non-monotonic dynamical behavior—that is, the amount of the uncertainty will first inflate, and subsequently decrease, with the growth of decoherence strengths in the two channels. In contrast, the uncertainty decreases monotonically with the growth of the purity of the initial state shared in prior. In order to reduce the measurement uncertainty in noisy environments, we put forward a remarkably effective strategy to steer the magnitude of uncertainty by means of a local non-unitary operation (i.e. weak measurement) on the qubit of interest. It turns out that this non-unitary operation can greatly reduce the entropic uncertainty, upon tuning the operation strength. Our investigations might thereby offer an insight into the dynamics and steering of entropic uncertainty in open systems.

Strain and electric-field tunable valley states in 2D van der Waals MoTe2/WTe2 heterostructures

NASA Astrophysics Data System (ADS)

Zheng, Zhida; Wang, Xiaocha; Mi, Wenbo

2016-12-01

The strain and electric-field effects on the electronic structure of MoTe2/WTe2 van der Waals heterostructures are investigated by first-principles calculations. The MoTe2/WTe2 heterostructures are indirect band gap semiconductors under different strains except for 2%. At a strain from  -6% to 6% under a zero electric field, the band gap is 0.56, 0.62, 0.69, 0.62, 0.46, 0.37 and 0.29 eV, respectively. Meanwhile, spin splitting at the conduction band minimum (CBM) decreases monotonically from 76-1 meV, and that at the valance band maximum (VBM) is 232, 266, 292, 307, 319, 302 and 283 meV. At an electric field from  -0.3 to 0.3 V Å-1 under a 2% strain, VBM splitting decreases from 499-77 meV, but CBM splitting almost remains at 33 meV. A semiconductor-metal transition appears at an electric field of  -0.3 V Å-1. At different electric fields under a  -4% strain, CBM splitting monotonically increases from 37-154 meV, but VBM splitting is 437, 438, 378, 273, 150, 78 and 134 meV, respectively. Our results can provide a more significant basis for spintronic and valleytronic devices.

Entropic depletion in colloidal suspensions and polymer liquids: Role of nanoparticle surface topography

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

Banerjee, Debapriya; Yang, Jian; Schweizer, Kenneth S.

2015-01-01

Here, we employ a hybrid Monte Carlo plus integral equation theory approach to study how dense fluids of small nanoparticles or polymer chains mediate entropic depletion interactions between topographically rough particles where all interaction potentials are hard core repulsion. The corrugated particle surfaces are composed of densely packed beads which present variable degrees of controlled topographic roughness and free volume associated with their geometric crevices. This pure entropy problem is characterized by competing ideal translational and (favorable and unfavorable) excess entropic contributions. Surface roughness generically reduces particle depletion aggregation relative to the smooth hard sphere case. However, the competition betweenmore » ideal and excess packing entropy effects in the bulk, near the particle surface and in the crevices, results in a non-monotonic variation of the particle-monomer packing correlation function as a function of the two dimensionless length scale ratios that quantify the effective surface roughness. As a result, the inter-particle potential of mean force (PMF), second virial coefficient, and spinodal miscibility volume fraction vary non-monotonically with the surface bead to monomer diameter and particle core to surface bead diameter ratios. A miscibility window is predicted corresponding to an optimum degree of surface roughness that completely destroys depletion attraction resulting in a repulsive PMF. Variation of the (dense) matrix packing fraction can enhance or suppress particle miscibility depending upon the amount of surface roughness. Connecting the monomers into polymer chains destabilizes the system via enhanced contact depletion attraction, but the non-monotonic variations with surface roughness metrics persist.« less

Rate Monotonic Analysis for Real-Time Systems

DTIC Science & Technology

1991-03-01

The essential goal of the Rate Monotonic Analysis (RMA) for Real - Time Systems Project at the Software Engineering Institute is to catalyze...improvement in the practice of real time systems engineering, specifically by increasing the use of rate monotonic analysis and scheduling algorithms. In this

Thermal effects on the enhanced ductility in non-monotonic uniaxial tension of DP780 steel sheet

NASA Astrophysics Data System (ADS)

Majidi, Omid; Barlat, Frederic; Korkolis, Yannis P.; Fu, Jiawei; Lee, Myoung-Gyu

2016-11-01

To understand the material behavior during non-monotonic loading, uniaxial tension tests were conducted in three modes, namely, the monotonic loading, loading with periodic relaxation and periodic loading-unloadingreloading, at different strain rates (0.001/s to 0.01/s). In this study, the temperature gradient developing during each test and its contribution to increasing the apparent ductility of DP780 steel sheets were considered. In order to assess the influence of temperature, isothermal uniaxial tension tests were also performed at three temperatures (298 K, 313 K and 328 K (25 °C, 40 °C and 55 °C)). A digital image correlation system coupled with an infrared thermography was used in the experiments. The results show that the non-monotonic loading modes increased the apparent ductility of the specimens. It was observed that compared with the monotonic loading, the temperature gradient became more uniform when a non-monotonic loading was applied.

Term frequency - function of document frequency: a new term weighting scheme for enterprise information retrieval

NASA Astrophysics Data System (ADS)

Zhang, Hui; Wang, Deqing; Wu, Wenjun; Hu, Hongping

2012-11-01

In today's business environment, enterprises are increasingly under pressure to process the vast amount of data produced everyday within enterprises. One method is to focus on the business intelligence (BI) applications and increasing the commercial added-value through such business analytics activities. Term weighting scheme, which has been used to convert the documents as vectors in the term space, is a vital task in enterprise Information Retrieval (IR), text categorisation, text analytics, etc. When determining term weight in a document, the traditional TF-IDF scheme sets weight value for the term considering only its occurrence frequency within the document and in the entire set of documents, which leads to some meaningful terms that cannot get the appropriate weight. In this article, we propose a new term weighting scheme called Term Frequency - Function of Document Frequency (TF-FDF) to address this issue. Instead of using monotonically decreasing function such as Inverse Document Frequency, FDF presents a convex function that dynamically adjusts weights according to the significance of the words in a document set. This function can be manually tuned based on the distribution of the most meaningful words which semantically represent the document set. Our experiments show that the TF-FDF can achieve higher value of Normalised Discounted Cumulative Gain in IR than that of TF-IDF and its variants, and improving the accuracy of relevance ranking of the IR results.

A DIRECT MEASUREMENT OF THE BARYONIC MASS FUNCTION OF GALAXIES AND IMPLICATIONS FOR THE GALACTIC BARYON FRACTION

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

Papastergis, Emmanouil; Huang, Shan; Giovanelli, Riccardo

We use both an H I-selected and an optically selected galaxy sample to directly measure the abundance of galaxies as a function of their 'baryonic' mass (stars + atomic gas). Stellar masses are calculated based on optical data from the Sloan Digital Sky Survey and atomic gas masses are calculated using atomic hydrogen (H I) emission line data from the Arecibo Legacy Fast ALFA survey. By using the technique of abundance matching, we combine the measured baryonic function of galaxies with the dark matter halo mass function in a {Lambda}CDM universe, in order to determine the galactic baryon fraction asmore » a function of host halo mass. We find that the baryon fraction of low-mass halos is much smaller than the cosmic value, even when atomic gas is taken into account. We find that the galactic baryon deficit increases monotonically with decreasing halo mass, in contrast with previous studies which suggested an approximately constant baryon fraction at the low-mass end. We argue that the observed baryon fractions of low-mass halos cannot be explained by reionization heating alone, and that additional feedback mechanisms (e.g., supernova blowout) must be invoked. However, the outflow rates needed to reproduce our result are not easily accommodated in the standard picture of galaxy formation in a {Lambda}CDM universe.« less

Relaxation Processes and Time Scale Transformation.

DTIC Science & Technology

1982-03-01

the response function may be immediately recognized as being 14 of the Kubo - Green type in the classical regime. Given this general framework, it is now...discussions of the master equation, 2and has recently been applied in cumulative damage models with discrete time parameter .3 However, it does not seem to...development parameter is taken tG be a positive, cumulative function that increases from an origin monotonically. Consider two continuous time scales e and t

Entropic inequalities for a class of quantum secret-sharing states

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

Sarvepalli, Pradeep

It is well known that von Neumann entropy is nonmonotonic, unlike Shannon entropy (which is monotonically nondecreasing). Consequently, it is difficult to relate the entropies of the subsystems of a given quantum state. In this paper, we show that if we consider quantum secret-sharing states arising from a class of monotone span programs, then we can partially recover the monotonicity of entropy for the so-called unauthorized sets. Furthermore, we can show for these quantum states that the entropy of the authorized sets is monotonically nonincreasing.

A discrete wavelet spectrum approach for identifying non-monotonic trends in hydroclimate data

NASA Astrophysics Data System (ADS)

Sang, Yan-Fang; Sun, Fubao; Singh, Vijay P.; Xie, Ping; Sun, Jian

2018-01-01

The hydroclimatic process is changing non-monotonically and identifying its trends is a great challenge. Building on the discrete wavelet transform theory, we developed a discrete wavelet spectrum (DWS) approach for identifying non-monotonic trends in hydroclimate time series and evaluating their statistical significance. After validating the DWS approach using two typical synthetic time series, we examined annual temperature and potential evaporation over China from 1961-2013 and found that the DWS approach detected both the warming and the warming hiatus in temperature, and the reversed changes in potential evaporation. Further, the identified non-monotonic trends showed stable significance when the time series was longer than 30 years or so (i.e. the widely defined climate timescale). The significance of trends in potential evaporation measured at 150 stations in China, with an obvious non-monotonic trend, was underestimated and was not detected by the Mann-Kendall test. Comparatively, the DWS approach overcame the problem and detected those significant non-monotonic trends at 380 stations, which helped understand and interpret the spatiotemporal variability in the hydroclimatic process. Our results suggest that non-monotonic trends of hydroclimate time series and their significance should be carefully identified, and the DWS approach proposed has the potential for wide use in the hydrological and climate sciences.

Near-threshold fatigue crack behaviour in EUROFER 97 at different temperatures

NASA Astrophysics Data System (ADS)

Aktaa, J.; Lerch, M.

2006-07-01

The fatigue crack behaviour in EUROFER 97 was investigated at room temperature (RT), 300, 500 and 550 °C for the assessment of cracks in first wall structures built from EUROFER 97 of future fusion reactors. For this purpose, fatigue crack growth tests were performed using CT specimens with two R-ratios, R = 0.1 and R = 0.5 ( R is the load ratio with R = Fmin/ Fmax where Fmin and Fmax are the minimum and maximum applied loads within a cycle, respectively). Hence, fatigue crack threshold, fatigue crack growth behaviour in the near-threshold range and their dependences on temperature and R-ratio were determined and described using an analytical formula. The fatigue crack threshold showed a monotonous dependence on temperature which is for R = 0.5 insignificantly small. The fatigue crack growth behaviour exhibited for R = 0.1 a non-monotonous dependence on temperature which is explained by the decrease of yield stress and the increase of creep damage with increasing temperature.

Non-monotonicity of Trace Distance Under Tensor Products

NASA Astrophysics Data System (ADS)

Maziero, Jonas

2015-10-01

The trace distance (TD) possesses several of the good properties required for a faithful distance measure in the quantum state space. Despite its importance and ubiquitous use in quantum information science, one of its questionable features, its possible non-monotonicity under taking tensor products of its arguments (NMuTP), has been hitherto unexplored. In this article, we advance analytical and numerical investigations of this issue considering different classes of states living in a discrete and finite dimensional Hilbert space. Our results reveal that although this property of TD does not show up for pure states and for some particular classes of mixed states, it is present in a non-negligible fraction of the regarded density operators. Hence, even though the percentage of quartets of states leading to the NMuTP drawback of TD and its strength decrease as the system's dimension grows, this property of TD must be taken into account before using it as a figure of merit for distinguishing mixed quantum states.

The Cognitive Social Network in Dreams: Transitivity, Assortativity, and Giant Component Proportion Are Monotonic.

PubMed

Han, Hye Joo; Schweickert, Richard; Xi, Zhuangzhuang; Viau-Quesnel, Charles

2016-04-01

For five individuals, a social network was constructed from a series of his or her dreams. Three important network measures were calculated for each network: transitivity, assortativity, and giant component proportion. These were monotonically related; over the five networks as transitivity increased, assortativity increased and giant component proportion decreased. The relations indicate that characters appear in dreams systematically. Systematicity likely arises from the dreamer's memory of people and their relations, which is from the dreamer's cognitive social network. But the dream social network is not a copy of the cognitive social network. Waking life social networks tend to have positive assortativity; that is, people tend to be connected to others with similar connectivity. Instead, in our sample of dream social networks assortativity is more often negative or near 0, as in online social networks. We show that if characters appear via a random walk, negative assortativity can result, particularly if the random walk is biased as suggested by remote associations. Copyright © 2015 Cognitive Science Society, Inc.

Simulation study of temperature-dependent diffusion behaviors of Ag/Ag(001) at low substrate temperature

NASA Astrophysics Data System (ADS)

Cai, Danyun; Mo, Yunjie; Feng, Xiaofang; He, Yingyou; Jiang, Shaoji

2017-06-01

In this study, a model based on the First Principles calculations and Kinetic Monte Carlo simulation were established to study the growth characteristic of Ag thin film at low substrate temperature. On the basis of the interaction between the adatom and nearest-neighbor atoms, some simplifications and assumptions were made to categorize the diffusion behaviors of Ag adatoms on Ag(001). Then the barriers of all possible diffusion behaviors were calculated using the Climbing Image Nudged Elastic Band method (CI-NEB). Based on the Arrhenius formula, the morphology variation, which is attributed to the surface diffusion behaviors during the growth, was simulated with a temperature-dependent KMC model. With this model, a non-monotonic relation between the surface roughness and the substrate temperature (decreasing from 300 K to 100 K) were discovered. The analysis of the temperature dependence on diffusion behaviors presents a theoretical explanation of diffusion mechanism for the non-monotonic variation of roughness at low substrate temperature.

Assessment of early onset of driver fatigue using multimodal fatigue measures in a static simulator.

PubMed

Jagannath, M; Balasubramanian, Venkatesh

2014-07-01

Driver fatigue is an important contributor to road accidents. This paper reports a study that evaluated driver fatigue using multimodal fatigue measures, i.e., surface electromyography (sEMG), electroencephalography (EEG), seat interface pressure, blood pressure, heart rate and oxygen saturation level. Twenty male participants volunteered in this study by performing 60 min of driving on a static simulator. Results from sEMG showed significant physical fatigue (ρ < 0.05) in back and shoulder muscle groups. EEG showed significant (ρ < 0.05) increase of alpha and theta activities and a significant decrease of beta activity during monotonous driving. Results also showed significant change in bilateral pressure distribution on thigh and buttocks region during the study. These findings demonstrate the use of multimodal measures to assess early onset of fatigue. This will help us understand the influence of physical and mental fatigue on driver during monotonous driving. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

A whole-brain computational modeling approach to explain the alterations in resting-state functional connectivity during progression of Alzheimer's disease.

PubMed

Demirtaş, Murat; Falcon, Carles; Tucholka, Alan; Gispert, Juan Domingo; Molinuevo, José Luis; Deco, Gustavo

2017-01-01

Alzheimer's disease (AD) is the most common dementia with dramatic consequences. The research in structural and functional neuroimaging showed altered brain connectivity in AD. In this study, we investigated the whole-brain resting state functional connectivity (FC) of the subjects with preclinical Alzheimer's disease (PAD), mild cognitive impairment due to AD (MCI) and mild dementia due to Alzheimer's disease (AD), the impact of APOE4 carriership, as well as in relation to variations in core AD CSF biomarkers. The synchronization in the whole-brain was monotonously decreasing during the course of the disease progression. Furthermore, in AD patients we found widespread significant decreases in functional connectivity (FC) strengths particularly in the brain regions with high global connectivity. We employed a whole-brain computational modeling approach to study the mechanisms underlying these alterations. To characterize the causal interactions between brain regions, we estimated the effective connectivity (EC) in the model. We found that the significant EC differences in AD were primarily located in left temporal lobe. Then, we systematically manipulated the underlying dynamics of the model to investigate simulated changes in FC based on the healthy control subjects. Furthermore, we found distinct patterns involving CSF biomarkers of amyloid-beta (Aβ1 - 42) total tau (t-tau) and phosphorylated tau (p-tau). CSF Aβ1 - 42 was associated to the contrast between healthy control subjects and clinical groups. Nevertheless, tau CSF biomarkers were associated to the variability in whole-brain synchronization and sensory integration regions. These associations were robust across clinical groups, unlike the associations that were found for CSF Aβ1 - 42. APOE4 carriership showed no significant correlations with the connectivity measures.

Voltage and frequency dependence of prestin-associated charge transfer

PubMed Central

Sun, Sean X.; Farrell, Brenda; Chana, Matthew S.; Oster, George; Brownell, William E.; Spector, Alexander A.

2009-01-01

Membrane protein prestin is a critical component of the motor complex that generates forces and dimensional changes in cells in response to changes in the cell membrane potential. In its native cochlear outer hair cell, prestin is crucial to the amplification and frequency selectivity of the mammalian ear up to frequencies of tens of kHz. Other cells transfected with prestin acquire voltage-dependent properties similar to those of the native cell. The protein performance is critically dependent on chloride ions, and intrinsic protein charges also play a role. We propose an electro-diffusion model to reveal the frequency and voltage dependence of electric charge transfer by prestin. The movement of the combined charge (i.e., anion and protein charges) across the membrane is described with a Fokker-Planck equation coupled to a kinetic equation that describes the binding of chloride ions to prestin. We found a voltage-and frequency-dependent phase shift between the transferred charge and the applied electric field that determines capacitive and resistive components of the transferred charge. The phase shift monotonically decreases from zero to -90 degree as a function of frequency. The capacitive component as a function of voltage is bell-shaped, and decreases with frequency. The resistive component is bell-shaped for both voltage and frequency. The capacitive and resistive components are similar to experimental measurements of charge transfer at high frequencies. The revealed nature of the transferred charge can help reconcile the high-frequency electrical and mechanical observations associated with prestin, and it is important for further analysis of the structure and function of this protein. PMID:19490917

A Bayesian Semiparametric Item Response Model with Dirichlet Process Priors

ERIC Educational Resources Information Center

Miyazaki, Kei; Hoshino, Takahiro

2009-01-01

In Item Response Theory (IRT), item characteristic curves (ICCs) are illustrated through logistic models or normal ogive models, and the probability that examinees give the correct answer is usually a monotonically increasing function of their ability parameters. However, since only limited patterns of shapes can be obtained from logistic models…

Wavefronts for a global reaction-diffusion population model with infinite distributed delay

NASA Astrophysics Data System (ADS)

Weng, Peixuan; Xu, Zhiting

2008-09-01

We consider a global reaction-diffusion population model with infinite distributed delay which includes models of Nicholson's blowflies and hematopoiesis derived by Gurney, Mackey and Glass, respectively. The existence of monotone wavefronts is derived by using the abstract settings of functional differential equations and Schauder fixed point theory.

Rigidity Sensing Explained by Active Matter Theory

PubMed Central

Marcq, Philippe; Yoshinaga, Natsuhiko; Prost, Jacques

2011-01-01

The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. We rationalize this observation using active matter theory, and propose that adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility. PMID:21943439

Stability and bifurcation analysis of three-species predator-prey model with non-monotonic delayed predator response

NASA Astrophysics Data System (ADS)

Balilo, Aldrin T.; Collera, Juancho A.

2018-03-01

In this paper, we consider delayed three-species predator-prey model with non-monotonic functional response where two predator populations feed on a single prey population. Response function in both predator populations includes a time delay which represents the gestation period of the predator populations. We call a positive equlibrium solution of the form E*S=(x*,y*,y*) as a symmetric equilibrium. The goal of this paper is to determine the effect of the difference in gestation periods of predator populations to the local dynamics of symmetric equilibria. Our results include conditions on the existence of equilibrium solutions, and stability and bifurcations of symmetric equilibria as the gestation periods of predator populations are varied. A numerical bifurcation analysis tool is also used to illustrate our results. Stability switch occurs at a Hopf bifurcation. Moreover, a branch of stable periodic solutions, obtained using numerical continuation, emerges from the Hopf bifurcation. This shows that the predator population with longer gestation period oscillates higher than the predator population with shorter gestation period.

Adjacent-Categories Mokken Models for Rater-Mediated Assessments

PubMed Central

Wind, Stefanie A.

2016-01-01

Molenaar extended Mokken’s original probabilistic-nonparametric scaling models for use with polytomous data. These polytomous extensions of Mokken’s original scaling procedure have facilitated the use of Mokken scale analysis as an approach to exploring fundamental measurement properties across a variety of domains in which polytomous ratings are used, including rater-mediated educational assessments. Because their underlying item step response functions (i.e., category response functions) are defined using cumulative probabilities, polytomous Mokken models can be classified as cumulative models based on the classifications of polytomous item response theory models proposed by several scholars. In order to permit a closer conceptual alignment with educational performance assessments, this study presents an adjacent-categories variation on the polytomous monotone homogeneity and double monotonicity models. Data from a large-scale rater-mediated writing assessment are used to illustrate the adjacent-categories approach, and results are compared with the original formulations. Major findings suggest that the adjacent-categories models provide additional diagnostic information related to individual raters’ use of rating scale categories that is not observed under the original formulation. Implications are discussed in terms of methods for evaluating rating quality. PMID:29795916

Considering spatial heterogeneity in the distributed lag non-linear model when analyzing spatiotemporal data.

PubMed

Chien, Lung-Chang; Guo, Yuming; Li, Xiao; Yu, Hwa-Lung

2018-01-01

The distributed lag non-linear (DLNM) model has been frequently used in time series environmental health research. However, its functionality for assessing spatial heterogeneity is still restricted, especially in analyzing spatiotemporal data. This study proposed a solution to take a spatial function into account in the DLNM, and compared the influence with and without considering spatial heterogeneity in a case study. This research applied the DLNM to investigate non-linear lag effect up to 7 days in a case study about the spatiotemporal impact of fine particulate matter (PM 2.5 ) on preschool children's acute respiratory infection in 41 districts of northern Taiwan during 2005 to 2007. We applied two spatiotemporal methods to impute missing air pollutant data, and included the Markov random fields to analyze district boundary data in the DLNM. When analyzing the original data without a spatial function, the overall PM 2.5 effect accumulated from all lag-specific effects had a slight variation at smaller PM 2.5 measurements, but eventually decreased to relative risk significantly <1 when PM 2.5 increased. While analyzing spatiotemporal imputed data without a spatial function, the overall PM 2.5 effect did not decrease but increased in monotone as PM 2.5 increased over 20 μg/m 3 . After adding a spatial function in the DLNM, spatiotemporal imputed data conducted similar results compared with the overall effect from the original data. Moreover, the spatial function showed a clear and uneven pattern in Taipei, revealing that preschool children living in 31 districts of Taipei were vulnerable to acute respiratory infection. Our findings suggest the necessity of including a spatial function in the DLNM to make a spatiotemporal analysis available and to conduct more reliable and explainable research. This study also revealed the analytical impact if spatial heterogeneity is ignored.

Method for beam hardening correction in quantitative computed X-ray tomography

NASA Technical Reports Server (NTRS)

Yan, Chye Hwang (Inventor); Whalen, Robert T. (Inventor); Napel, Sandy (Inventor)

2001-01-01

Each voxel is assumed to contain exactly two distinct materials, with the volume fraction of each material being iteratively calculated. According to the method, the spectrum of the X-ray beam must be known, and the attenuation spectra of the materials in the object must be known, and be monotonically decreasing with increasing X-ray photon energy. Then, a volume fraction is estimated for the voxel, and the spectrum is iteratively calculated.

Conditional uncertainty principle

NASA Astrophysics Data System (ADS)

Gour, Gilad; Grudka, Andrzej; Horodecki, Michał; Kłobus, Waldemar; Łodyga, Justyna; Narasimhachar, Varun

2018-04-01

We develop a general operational framework that formalizes the concept of conditional uncertainty in a measure-independent fashion. Our formalism is built upon a mathematical relation which we call conditional majorization. We define conditional majorization and, for the case of classical memory, we provide its thorough characterization in terms of monotones, i.e., functions that preserve the partial order under conditional majorization. We demonstrate the application of this framework by deriving two types of memory-assisted uncertainty relations, (1) a monotone-based conditional uncertainty relation and (2) a universal measure-independent conditional uncertainty relation, both of which set a lower bound on the minimal uncertainty that Bob has about Alice's pair of incompatible measurements, conditioned on arbitrary measurement that Bob makes on his own system. We next compare the obtained relations with their existing entropic counterparts and find that they are at least independent.

Entanglement quantification by local unitary operations

NASA Astrophysics Data System (ADS)

Monras, A.; Adesso, G.; Giampaolo, S. M.; Gualdi, G.; Davies, G. B.; Illuminati, F.

2011-07-01

Invariance under local unitary operations is a fundamental property that must be obeyed by every proper measure of quantum entanglement. However, this is not the only aspect of entanglement theory where local unitary operations play a relevant role. In the present work we show that the application of suitable local unitary operations defines a family of bipartite entanglement monotones, collectively referred to as “mirror entanglement.” They are constructed by first considering the (squared) Hilbert-Schmidt distance of the state from the set of states obtained by applying to it a given local unitary operator. To the action of each different local unitary operator there corresponds a different distance. We then minimize these distances over the sets of local unitary operations with different spectra, obtaining an entire family of different entanglement monotones. We show that these mirror-entanglement monotones are organized in a hierarchical structure, and we establish the conditions that need to be imposed on the spectrum of a local unitary operator for the associated mirror entanglement to be faithful, i.e., to vanish in and only in separable pure states. We analyze in detail the properties of one particularly relevant member of the family, the “stellar mirror entanglement” associated with the traceless local unitary operations with nondegenerate spectra and equispaced eigenvalues in the complex plane. This particular measure generalizes the original analysis of S. M. Giampaolo and F. Illuminati [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.76.042301 76, 042301 (2007)], valid for qubits and qutrits. We prove that the stellar entanglement is a faithful bipartite entanglement monotone in any dimension and that it is bounded from below by a function proportional to the linear entropy and from above by the linear entropy itself, coinciding with it in two- and three-dimensional spaces.

Entanglement quantification by local unitary operations

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

Monras, A.; Giampaolo, S. M.; Gualdi, G.

2011-07-15

Invariance under local unitary operations is a fundamental property that must be obeyed by every proper measure of quantum entanglement. However, this is not the only aspect of entanglement theory where local unitary operations play a relevant role. In the present work we show that the application of suitable local unitary operations defines a family of bipartite entanglement monotones, collectively referred to as ''mirror entanglement.'' They are constructed by first considering the (squared) Hilbert-Schmidt distance of the state from the set of states obtained by applying to it a given local unitary operator. To the action of each different localmore » unitary operator there corresponds a different distance. We then minimize these distances over the sets of local unitary operations with different spectra, obtaining an entire family of different entanglement monotones. We show that these mirror-entanglement monotones are organized in a hierarchical structure, and we establish the conditions that need to be imposed on the spectrum of a local unitary operator for the associated mirror entanglement to be faithful, i.e., to vanish in and only in separable pure states. We analyze in detail the properties of one particularly relevant member of the family, the ''stellar mirror entanglement'' associated with the traceless local unitary operations with nondegenerate spectra and equispaced eigenvalues in the complex plane. This particular measure generalizes the original analysis of S. M. Giampaolo and F. Illuminati [Phys. Rev. A 76, 042301 (2007)], valid for qubits and qutrits. We prove that the stellar entanglement is a faithful bipartite entanglement monotone in any dimension and that it is bounded from below by a function proportional to the linear entropy and from above by the linear entropy itself, coinciding with it in two- and three-dimensional spaces.« less

Destabilizing geometrical and bimaterial effects in frictional sliding

NASA Astrophysics Data System (ADS)

Aldam, M.; Bar Sinai, Y.; Svetlizky, I.; Fineberg, J.; Brener, E.; Xu, S.; Ben-Zion, Y.; Bouchbinder, E.

2017-12-01

Asymmetry of the two blocks forming a fault plane, i.e. the lack of reflection symmetry with respect to the fault plane, either geometrical or material, gives rise to generic destabilizing effects associated with the elastodynamic coupling between slip and normal stress variations. While geometric asymmetry exists in various geophysical contexts, such as thrust faults and landslide systems, its effect on fault dynamics is often overlooked. In the first part of the talk, I will show that geometrical asymmetry alone can destabilize velocity-strengthening faults, which are otherwise stable. I will further show that geometrical asymmetry accounts for a significant weakening effect observed in rupture propagation and present laboratory data that support the theory. In the second part of the talk, I will focus on material asymmetry and discuss an unexpected property of the well-studied frictional bimaterial effect. I will show that while the bimaterial coupling between slip and normal stress variations is a monotonically increasing function of the bimaterial contrast, when it is coupled to interfacial shear stress perturbations through a friction law, various physical quantities exhibit a non-monotonic dependence on the bimaterial contrast. This non-monotonicity is demonstrated for the stability of steady-sliding and for unsteady rupture propagation in faults described by various friction laws (regularized Coulomb, slip-weakening, rate-and-state friction), using analytic and numerical tools. All in all, the importance of bulk asymmetry to interfacial fault dynamics is highlighted. [1] Michael Aldam, Yohai Bar-Sinai, Ilya Svetlizky, Efim A. Brener, Jay Fineberg, and Eran Bouchbinder. Frictional Sliding without Geometrical Reflection Symmetry. Phys. Rev. X, 6(4):041023, 2016. [2] Michael Aldam, Shiqing Xu, Efim A. Brener, Yehuda Ben-Zion, and Eran Bouchbinder. Non-monotonicity of the frictional bimaterial effect. arXiv:1707.01132, 2017.

A simple algorithm for computing positively weighted straight skeletons of monotone polygons☆

PubMed Central

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

2015-01-01

We study the characteristics of straight skeletons of monotone polygonal chains and use them to devise an algorithm for computing positively weighted straight skeletons of monotone polygons. Our algorithm runs in O(nlog⁡n) time and O(n) space, where n denotes the number of vertices of the polygon. PMID:25648376

A simple algorithm for computing positively weighted straight skeletons of monotone polygons.

PubMed

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

2015-02-01

We study the characteristics of straight skeletons of monotone polygonal chains and use them to devise an algorithm for computing positively weighted straight skeletons of monotone polygons. Our algorithm runs in [Formula: see text] time and [Formula: see text] space, where n denotes the number of vertices of the polygon.

The acoustical bright spot and mislocalization of tones by human listeners

PubMed Central

Macaulay, Eric J.; Hartmann, William M.; Rakerd, Brad

2010-01-01

Listeners attempted to localize 1500-Hz sine tones presented in free field from a loudspeaker array, spanning azimuths from 0° (straight ahead) to 90° (extreme right). During this task, the tone levels and phases were measured in the listeners’ ear canals. Because of the acoustical bright spot, measured interaural level differences (ILD) were non-monotonic functions of azimuth with a maximum near 55°. In a source-identification task, listeners’ localization decisions closely tracked the non-monotonic ILD, and thus became inaccurate at large azimuths. When listeners received training and feedback, their accuracy improved only slightly. In an azimuth-discrimination task, listeners decided whether a first sound was to the left or to the right of a second. The discrimination results also reflected the confusion caused by the non-monotonic ILD, and they could be predicted approximately by a listener’s identification results. When the sine tones were amplitude modulated or replaced by narrow bands of noise, interaural time difference (ITD) cues greatly reduced the confusion for most listeners, but not for all. Recognizing the important role of the bright spot requires a reevaluation of the transition between the low-frequency region for localization (mainly ITD) and the high-frequency region (mainly ILD). PMID:20329844

Using Polynomials to Simplify Fixed Pattern Noise and Photometric Correction of Logarithmic CMOS Image Sensors

PubMed Central

Li, Jing; Mahmoodi, Alireza; Joseph, Dileepan

2015-01-01

An important class of complementary metal-oxide-semiconductor (CMOS) image sensors are those where pixel responses are monotonic nonlinear functions of light stimuli. This class includes various logarithmic architectures, which are easily capable of wide dynamic range imaging, at video rates, but which are vulnerable to image quality issues. To minimize fixed pattern noise (FPN) and maximize photometric accuracy, pixel responses must be calibrated and corrected due to mismatch and process variation during fabrication. Unlike literature approaches, which employ circuit-based models of varying complexity, this paper introduces a novel approach based on low-degree polynomials. Although each pixel may have a highly nonlinear response, an approximately-linear FPN calibration is possible by exploiting the monotonic nature of imaging. Moreover, FPN correction requires only arithmetic, and an optimal fixed-point implementation is readily derived, subject to a user-specified number of bits per pixel. Using a monotonic spline, involving cubic polynomials, photometric calibration is also possible without a circuit-based model, and fixed-point photometric correction requires only a look-up table. The approach is experimentally validated with a logarithmic CMOS image sensor and is compared to a leading approach from the literature. The novel approach proves effective and efficient. PMID:26501287

Testing and Estimating Shape-Constrained Nonparametric Density and Regression in the Presence of Measurement Error.

PubMed

Carroll, Raymond J; Delaigle, Aurore; Hall, Peter

2011-03-01

In many applications we can expect that, or are interested to know if, a density function or a regression curve satisfies some specific shape constraints. For example, when the explanatory variable, X, represents the value taken by a treatment or dosage, the conditional mean of the response, Y , is often anticipated to be a monotone function of X. Indeed, if this regression mean is not monotone (in the appropriate direction) then the medical or commercial value of the treatment is likely to be significantly curtailed, at least for values of X that lie beyond the point at which monotonicity fails. In the case of a density, common shape constraints include log-concavity and unimodality. If we can correctly guess the shape of a curve, then nonparametric estimators can be improved by taking this information into account. Addressing such problems requires a method for testing the hypothesis that the curve of interest satisfies a shape constraint, and, if the conclusion of the test is positive, a technique for estimating the curve subject to the constraint. Nonparametric methodology for solving these problems already exists, but only in cases where the covariates are observed precisely. However in many problems, data can only be observed with measurement errors, and the methods employed in the error-free case typically do not carry over to this error context. In this paper we develop a novel approach to hypothesis testing and function estimation under shape constraints, which is valid in the context of measurement errors. Our method is based on tilting an estimator of the density or the regression mean until it satisfies the shape constraint, and we take as our test statistic the distance through which it is tilted. Bootstrap methods are used to calibrate the test. The constrained curve estimators that we develop are also based on tilting, and in that context our work has points of contact with methodology in the error-free case.

Social opinion dynamics is not chaotic

NASA Astrophysics Data System (ADS)

Lim, Chjan; Zhang, Weituo

2016-08-01

Motivated by the research on social opinion dynamics over large and dense networks, a general framework for verifying the monotonicity property of multi-agent dynamics is introduced. This allows a derivation of sociologically meaningful sufficient conditions for monotonicity that are tailor-made for social opinion dynamics, which typically have high nonlinearity. A direct consequence of monotonicity is that social opinion dynamics is nonchaotic. A key part of this framework is the definition of a partial order relation that is suitable for a large class of social opinion dynamics such as the generalized naming games. Comparisons are made to previous techniques to verify monotonicity. Using the results obtained, we extend many of the consequences of monotonicity to this class of social dynamics, including several corollaries on their asymptotic behavior, such as global convergence to consensus and tipping points of a minority fraction of zealots or leaders.

Restoration of Monotonicity Respecting in Dynamic Regression

PubMed Central

Huang, Yijian

2017-01-01

Dynamic regression models, including the quantile regression model and Aalen’s additive hazards model, are widely adopted to investigate evolving covariate effects. Yet lack of monotonicity respecting with standard estimation procedures remains an outstanding issue. Advances have recently been made, but none provides a complete resolution. In this article, we propose a novel adaptive interpolation method to restore monotonicity respecting, by successively identifying and then interpolating nearest monotonicity-respecting points of an original estimator. Under mild regularity conditions, the resulting regression coefficient estimator is shown to be asymptotically equivalent to the original. Our numerical studies have demonstrated that the proposed estimator is much more smooth and may have better finite-sample efficiency than the original as well as, when available as only in special cases, other competing monotonicity-respecting estimators. Illustration with a clinical study is provided. PMID:29430068

Multiple metals predict prolactin and thyrotropin (TSH) levels in men

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

Meeker, John D., E-mail: meekerj@umich.edu; Rossano, Mary G.; Protas, Bridget

2009-10-15

Exposure to a number of metals can affect neuroendocrine and thyroid signaling, which can result in adverse effects on development, behavior, metabolism, reproduction, and other functions. The present study assessed the relationship between metal concentrations in blood and serum prolactin (PRL) and thyrotropin (TSH) levels, markers of dopaminergic, and thyroid function, respectively, among men participating in a study of environmental influences on male reproductive health. Blood samples from 219 men were analyzed for concentrations of 11 metals and serum levels of PRL and TSH. In multiple linear regression models adjusted for age, BMI and smoking, PRL was inversely associated withmore » arsenic, cadmium, copper, lead, manganese, molybdenum, and zinc, but positively associated with chromium. Several of these associations (Cd, Pb, Mo) are consistent with limited studies in humans or animals, and a number of the relationships (Cr, Cu, Pb, Mo) remained when additionally considering multiple metals in the model. Lead and copper were associated with non-monotonic decrease in TSH, while arsenic was associated with a dose-dependent increase in TSH. For arsenic these findings were consistent with recent experimental studies where arsenic inhibited enzymes involved in thyroid hormone synthesis and signaling. More research is needed for a better understanding of the role of metals in neuroendocrine and thyroid function and related health implications.« less

Distortion-product otoacoustic emission suppression tuning curves in humans

PubMed Central

Gorga, Michael P.; Neely, Stephen T.; Kopun, Judy; Tan, Hongyang

2011-01-01

Distortion-product otoacoustic emission (DPOAE) suppression data as a function of suppressor level (L3) for f2 frequencies from 0.5 to 8 kHz and L2 levels from 10 to 60 dB sensation level were used to construct suppression tuning curves (STCs). DPOAE levels in the presence of suppressors were converted into decrement versus L3 functions, and the L3 levels resulting in 3 dB decrements were derived by transformed linear regression. These L3 levels were plotted as a function of f3 to construct STCs. When f3 is represented on an octave scale, STCs were similar in shape across f2 frequency. These STCs were analyzed to provide estimates of gain (tip-to-tail difference) and tuning (QERB). Both gain and tuning decreased as L2 increased, regardless of f2, but the trend with f2 was not monotonic. A roughly linear relation was observed between gain and tuning at each frequency, such that gain increased by 4–16 dB (mean ≈ 5 dB) for every unit increase in QERB, although the pattern varied with frequency. These findings suggest consistent nonlinear processing across a wide frequency range in humans, although the nonlinear operation range is frequency dependent. PMID:21361440

A Unimodal Model for Double Observer Distance Sampling Surveys.

PubMed

Becker, Earl F; Christ, Aaron M

2015-01-01

Distance sampling is a widely used method to estimate animal population size. Most distance sampling models utilize a monotonically decreasing detection function such as a half-normal. Recent advances in distance sampling modeling allow for the incorporation of covariates into the distance model, and the elimination of the assumption of perfect detection at some fixed distance (usually the transect line) with the use of double-observer models. The assumption of full observer independence in the double-observer model is problematic, but can be addressed by using the point independence assumption which assumes there is one distance, the apex of the detection function, where the 2 observers are assumed independent. Aerially collected distance sampling data can have a unimodal shape and have been successfully modeled with a gamma detection function. Covariates in gamma detection models cause the apex of detection to shift depending upon covariate levels, making this model incompatible with the point independence assumption when using double-observer data. This paper reports a unimodal detection model based on a two-piece normal distribution that allows covariates, has only one apex, and is consistent with the point independence assumption when double-observer data are utilized. An aerial line-transect survey of black bears in Alaska illustrate how this method can be applied.

Electronic polarizability and interaction parameter of gadolinium tungsten borate glasses with high WO{sub 3} content

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

Taki, Yukina; Shinozaki, Kenji; Honma, Tsuyoshi

2014-12-15

Glasses with the compositions of 25Gd{sub 2}O{sub 3}–xWO{sub 3}–(75−x)B{sub 2}O{sub 3} with x=25–65 were prepared by using a conventional melt quenching method, and their electronic polarizabilities, optical basicities Λ(n{sub o}), and interaction parameters A(n{sub o}) were estimated from density and refractive index measurements in order to clarify the feature of electronic polarizability and bonding states in the glasses with high WO{sub 3} contents. The optical basicity of the glasses increases monotonously with the substitution of WO{sub 3} for B{sub 2}O{sub 3}, and contrary the interaction parameter decreases monotonously with increasing WO{sub 3} content. A good linear correlation was observed betweenmore » Λ(n{sub o}) and A(n{sub o}) and between the glass transition temperature and A(n{sub o}). It was proposed that Gd{sub 2}O{sub 3} oxide belongs to the category of basic oxide with a value of A(n{sub o})=0.044 Å{sup −3} as similar to WO{sub 3}. The relationship between the glass formation and electronic polarizability in the glasses was discussed, and it was proposed that the glasses with high WO{sub 3} and Gd{sub 2}O{sub 3} contents would be a floppy network system consisting of mainly basic oxides. - Graphical abstract: This figure shows the correlation between the optical basicity and interaction parameter in borate-based glasses. The data obtained in the present study for Gd{sub 2}O{sub 3}–WO{sub 3}–B{sub 2}O{sub 3} glasses are locating in the correlation line for other borate glasses. These results shown in Fig. 8 clearly demonstrate that Gd{sub 2}O{sub 3}–WO{sub 3}–B{sub 2}O{sub 3} glasses having a wide range of optical basicity and interaction parameter are regarded as glasses consisting of acidic and basic oxides. - Highlights: • Gd{sub 2}O{sub 3}–WO{sub 3}–B{sub 2}O{sub 3} glasses with high WO{sub 3} contents were prepared. • Electronic polarizability and interaction parameter were estimated. • Optical basicity increases monotonously with increasing WO{sub 3} content. • Interaction parameter decreases monotonously with increasing WO{sub 3} content. • Glasses with high WO{sub 3}contents is regarded as a floppy network system.« less

Monotonicity-based electrical impedance tomography for lung imaging

NASA Astrophysics Data System (ADS)

Zhou, Liangdong; Harrach, Bastian; Seo, Jin Keun

2018-04-01

This paper presents a monotonicity-based spatiotemporal conductivity imaging method for continuous regional lung monitoring using electrical impedance tomography (EIT). The EIT data (i.e. the boundary current-voltage data) can be decomposed into pulmonary, cardiac and other parts using their different periodic natures. The time-differential current-voltage operator corresponding to the lung ventilation can be viewed as either semi-positive or semi-negative definite owing to monotonic conductivity changes within the lung regions. We used these monotonicity constraints to improve the quality of lung EIT imaging. We tested the proposed methods in numerical simulations, phantom experiments and human experiments.

Investigating the Structural, Thermal, and Electronic Properties of the Zircon-Type ZrSiO4, ZrGeO4 and HfSiO4 Compounds

NASA Astrophysics Data System (ADS)

Chiker, Fafa; Boukabrine, Fatiha; Khachai, H.; Khenata, R.; Mathieu, C.; Bin Omran, S.; Syrotyuk, S. V.; Ahmed, W. K.; Murtaza, G.

2016-11-01

In the present study, the structural, thermal, and electronic properties of some important orthosilicate dielectrics, such as the ZrSiO4, ZrGeO4, and HfSiO4 compounds, have been investigated theoretically with the use of first-principle calculations. We attribute the application of the modified Becke-Johnson exchange potential, which is basically an improvement over the local density approximation and the Perdew-Burke-Ernzerhof exchange-correlation functional, for a better description of the band gaps of the compounds. This resulted in a good agreement with our estimated values in comparison with the reported experimental data, specifically for the ZrSiO4, and HfSiO4 compounds. Conversely, for the ZrGeO4 compound, the calculated electronic band structure shows a direct band gap at the Γ point with the value of 5.79 eV. Furthermore, our evaluated thermal properties that are calculated by using the quasi-harmonic Debye model indicated that the volume variation with temperature is higher in the ZrGeO4 compound as compared to both the ZrSiO4 and HfSiO4 compounds, which is ascribed to the difference between the electron shells of the Si and Ge atoms. Therefore, these results also indicate that while the entropy ( S) and enthalpy ( U) parameters increase monotonically, the free energy ( G), in contrast, decreases monotonically with increasing temperature, respectively. Moreover, the pressure and temperature dependencies of the Debye temperature Θ, thermal expansion coefficient, and heat capacities C V were also predicted in our study.

Heterogeneous Suppression of Sequential Effects in Random Sequence Generation, but Not in Operant Learning.

PubMed

Shteingart, Hanan; Loewenstein, Yonatan

2016-01-01

There is a long history of experiments in which participants are instructed to generate a long sequence of binary random numbers. The scope of this line of research has shifted over the years from identifying the basic psychological principles and/or the heuristics that lead to deviations from randomness, to one of predicting future choices. In this paper, we used generalized linear regression and the framework of Reinforcement Learning in order to address both points. In particular, we used logistic regression analysis in order to characterize the temporal sequence of participants' choices. Surprisingly, a population analysis indicated that the contribution of the most recent trial has only a weak effect on behavior, compared to more preceding trials, a result that seems irreconcilable with standard sequential effects that decay monotonously with the delay. However, when considering each participant separately, we found that the magnitudes of the sequential effect are a monotonous decreasing function of the delay, yet these individual sequential effects are largely averaged out in a population analysis because of heterogeneity. The substantial behavioral heterogeneity in this task is further demonstrated quantitatively by considering the predictive power of the model. We show that a heterogeneous model of sequential dependencies captures the structure available in random sequence generation. Finally, we show that the results of the logistic regression analysis can be interpreted in the framework of reinforcement learning, allowing us to compare the sequential effects in the random sequence generation task to those in an operant learning task. We show that in contrast to the random sequence generation task, sequential effects in operant learning are far more homogenous across the population. These results suggest that in the random sequence generation task, different participants adopt different cognitive strategies to suppress sequential dependencies when generating the "random" sequences.

Noise-induced modulation of the relaxation kinetics around a non-equilibrium steady state of non-linear chemical reaction networks.

PubMed

Ramaswamy, Rajesh; Sbalzarini, Ivo F; González-Segredo, Nélido

2011-01-28

Stochastic effects from correlated noise non-trivially modulate the kinetics of non-linear chemical reaction networks. This is especially important in systems where reactions are confined to small volumes and reactants are delivered in bursts. We characterise how the two noise sources confinement and burst modulate the relaxation kinetics of a non-linear reaction network around a non-equilibrium steady state. We find that the lifetimes of species change with burst input and confinement. Confinement increases the lifetimes of all species that are involved in any non-linear reaction as a reactant. Burst monotonically increases or decreases lifetimes. Competition between burst-induced and confinement-induced modulation may hence lead to a non-monotonic modulation. We quantify lifetime as the integral of the time autocorrelation function (ACF) of concentration fluctuations around a non-equilibrium steady state of the reaction network. Furthermore, we look at the first and second derivatives of the ACF, each of which is affected in opposite ways by burst and confinement. This allows discriminating between these two noise sources. We analytically derive the ACF from the linear Fokker-Planck approximation of the chemical master equation in order to establish a baseline for the burst-induced modulation at low confinement. Effects of higher confinement are then studied using a partial-propensity stochastic simulation algorithm. The results presented here may help understand the mechanisms that deviate stochastic kinetics from its deterministic counterpart. In addition, they may be instrumental when using fluorescence-lifetime imaging microscopy (FLIM) or fluorescence-correlation spectroscopy (FCS) to measure confinement and burst in systems with known reaction rates, or, alternatively, to correct for the effects of confinement and burst when experimentally measuring reaction rates.

Properties of the probability density function of the non-central chi-squared distribution

NASA Astrophysics Data System (ADS)

András, Szilárd; Baricz, Árpád

2008-10-01

In this paper we consider the probability density function (pdf) of a non-central [chi]2 distribution with arbitrary number of degrees of freedom. For this function we prove that can be represented as a finite sum and we deduce a partial derivative formula. Moreover, we show that the pdf is log-concave when the degrees of freedom is greater or equal than 2. At the end of this paper we present some Turán-type inequalities for this function and an elegant application of the monotone form of l'Hospital's rule in probability theory is given.

Bulk Dissolution Rates of Cadmium and Bismuth Tellurides As a Function of pH, Temperature and Dissolved Oxygen.

PubMed

Biver, Marc; Filella, Montserrat

2016-05-03

The toxicity of Cd being well established and that of Te suspected, the bulk, surface-normalized steady-state dissolution rates of two industrially important binary tellurides-polycrystalline cadmium and bismuth tellurides- were studied over the pH range 3-11, at various temperatures (25-70 °C) and dissolved oxygen concentrations (0-100% O2 in the gas phase). The behavior of both tellurides is strikingly different. The dissolution rates of CdTe monotonically decreased with increasing pH, the trend becoming more pronounced with increasing temperature. Activation energies were of the order of magnitude associated with surface controlled processes; they decreased with decreasing acidity. At pH 7, the CdTe dissolution rate increased linearly with dissolved oxygen. In anoxic solution, CdTe dissolved at a finite rate. In contrast, the dissolution rate of Bi2Te3 passed through a minimum at pH 5.3. The activation energy had a maximum in the rate minimum at pH 5.3 and fell below the threshold for diffusion control at pH 11. No oxygen dependence was detected. Bi2Te3 dissolves much more slowly than CdTe; from one to more than 3.5 orders of magnitude in the Bi2Te3 rate minimum. Both will readily dissolve under long-term landfill deposition conditions but comparatively slowly.

Stochastic mechanics of loose boundary particle transport in turbulent flow

NASA Astrophysics Data System (ADS)

Dey, Subhasish; Ali, Sk Zeeshan

2017-05-01

In a turbulent wall shear flow, we explore, for the first time, the stochastic mechanics of loose boundary particle transport, having variable particle protrusions due to various cohesionless particle packing densities. The mean transport probabilities in contact and detachment modes are obtained. The mean transport probabilities in these modes as a function of Shields number (nondimensional fluid induced shear stress at the boundary) for different relative particle sizes (ratio of boundary roughness height to target particle diameter) and shear Reynolds numbers (ratio of fluid inertia to viscous damping) are presented. The transport probability in contact mode increases with an increase in Shields number attaining a peak and then decreases, while that in detachment mode increases monotonically. For the hydraulically transitional and rough flow regimes, the transport probability curves in contact mode for a given relative particle size of greater than or equal to unity attain their peaks corresponding to the averaged critical Shields numbers, from where the transport probability curves in detachment mode initiate. At an inception of particle transport, the mean probabilities in both the modes increase feebly with an increase in shear Reynolds number. Further, for a given particle size, the mean probability in contact mode increases with a decrease in critical Shields number attaining a critical value and then increases. However, the mean probability in detachment mode increases with a decrease in critical Shields number.

Debye ring diffraction elucidation of 2D photonic crystal self-assembly and ordering at the air-water interface.

PubMed

Smith, N L; Coukouma, A; Dubnik, S; Asher, S A

2017-12-06

We fabricate 2D photonic crystals (2DPC) by spreading a dispersion of charged colloidal particles (diameters = 409, 570, and 915 nm) onto the surface of electrolyte solutions using a needle tip flow method. When the interparticle electrostatic interaction potential is large, particles self-assemble into highly ordered hexagonal close packed (hcp) monolayers. Ordered 2DPC efficiently forward diffract monochromatic light to produce a Debye ring on a screen parallel to the 2DPC. The diameter of the Debye ring is inversely proportional to the 2DPC particle spacing, while the Debye ring brightness and thickness depends on the 2DPC ordering. The Debye ring thickness increases as the 2DPC order decreases. The Debye ring ordering measurements of 2DPC attached to glass slides track measurements of the 2D pair correlation function order parameter calculated from SEM micrographs. The Debye ring method was used to investigate the 2DPC particle spacing, and ordering at the air-solution interface of NaCl solutions, and for 2DPC arrays attached to glass slides. Surprisingly, the 2DPC ordering does not monotonically decrease as the salt concentration increases. This is because of chloride ion adsorption onto the anionic particle surfaces. This adsorption increases the particle surface charge and compensates for the decreased Debye length of the electric double layer when the NaCl concentration is below a critical value.

Impact of surface strain on the spin dynamics of deposited Co nanowires

NASA Astrophysics Data System (ADS)

Polyakov, O. P.; Korobova, J. G.; Stepanyuk, O. V.; Bazhanov, D. I.

2017-01-01

Tailoring the magnetic properties at atomic-scale is essential in the engineering of modern spintronics devices. One of the main concerns in the novel nanostructured materials design is the decrease of the paid energy in the way of functioning, but allowing to switch between different magnetic states with a relative low-cost energy at the same time. Magnetic anisotropy (MA) energy defines the stability of a spin in the preferred direction and is a fundamental variable in magnetization switching processes. Transition-metal wires are known to develop large, stable spin and orbital magnetic moments together with MA energies that are orders of magnitude larger than in the corresponding solids. Different ways of controlling the MA have been exploited such as alloying, surface charging, and external electrical fields. Here we investigate from a first-principle approach together with dynamic calculations, the surface strain driven mechanism to tune the magnetic properties of deposited nanowires. We consider as a prototype system, the monoatomic Co wires deposited on strained Pt(111) and Au(111) surfaces. Our first-principles calculations reveal a monotonic increase/decrease of MA energy under compressive/tensile strain in supported Co wire. Moreover, the spin dynamics studies based on solving the Landau-Lifshitz-Gilbert equation show that the induced surface-strain leads to a substantial decrease of the required external magnetic field magnitude for magnetization switching in Co wire.

Picoelectrospray Ionization Mass Spectrometry Using Narrow-bore Chemically Etched Emitters

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

Marginean, Ioan; Tang, Keqi; Smith, Richard D.

2014-01-01

Electrospray ionization mass spectrometry (ESI-MS) at flow rates below ~10 nL/min has been only sporadically explored due to difficulty in reproducibly fabricating emitters that can operate at lower flow rates. Here we demonstrate narrow orifice chemically etched emitters for stable electrospray at flow rates as low as 400 pL/min. Depending on the analyte concentration, we observe two types of MS signal response as a function of flow rate. At low concentrations, an optimum flow rate is observed slightly above 1 nL/min, while the signal decreases monotonically with decreasing flow rates at higher concentrations. In spite of lower MS signal, themore » ion utilization efficiency increases exponentially with decreasing flow rate in all cases. No unimolecular response was observed within this flow rate range during the analysis of an equimolar mixture of peptides, indicating that ionization efficiency is an analyte-dependent characteristic in given experimental conditions. While little to no gain in signal-to-noise was achieved at ultralow flow rates for concentration-limited analyses, experiments consuming the same amount of analyte suggest that mass-limited analyses will benefit strongly from the use of low flow rates and avoiding unnecessary sample dilution. By operating under optimal conditions, consumption of just 500 zmol of sample yielded signal-to-noise ratios ~10 for some peptides. These findings have important implications for the analysis of trace biological samples.« less

An Alternative Perspective on von Winterfeldt et al.'s (1997) Test of Consequence Monotonicity

ERIC Educational Resources Information Center

Ho, Moon-Ho R.; Regenwetter, Michel; Niederee, Reinhard; Heyer, Dieter

2005-01-01

D. von Winterfeldt, N.-K. Chung, R. D. Luce, and Y. Cho (see record 1997-03378-008) provided several tests for consequence monotonicity of choice or judgment, using certainty equivalents of gambles. The authors reaxiomatized consequence monotonicity in a probabilistic framework and reanalyzed von Winterfeldt et al.'s main experiment via a…

Investigations into the shape-preserving interpolants using symbolic computation

NASA Technical Reports Server (NTRS)

Lam, Maria

1988-01-01

Shape representation is a central issue in computer graphics and computer-aided geometric design. Many physical phenomena involve curves and surfaces that are monotone (in some directions) or are convex. The corresponding representation problem is given some monotone or convex data, and a monotone or convex interpolant is found. Standard interpolants need not be monotone or convex even though they may match monotone or convex data. Most of the methods of investigation of this problem involve the utilization of quadratic splines or Hermite polynomials. In this investigation, a similar approach is adopted. These methods require derivative information at the given data points. The key to the problem is the selection of the derivative values to be assigned to the given data points. Schemes for choosing derivatives were examined. Along the way, fitting given data points by a conic section has also been investigated as part of the effort to study shape-preserving quadratic splines.

Correlations between critical current density, j{sub c}, critical temperature, T{sub c}, and structural quality of Y{sub 1}B{sub 2}Cu{sub 3}O{sub 7-x} thin superconducting films

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

Chrzanowski, J.; Xing, W.B.; Atlan, D.

1994-12-31

Correlations between critical current density (j{sub c}) critical temperature (T{sub c}) and the density of edge dislocations and nonuniform strain have been observed in YBCO thin films deposited by pulsed laser ablation on (001) LaAlO{sub 3} single crystals. Distinct maxima in j{sub c} as a function of the linewidths of the (00{ell}) Bragg reflections and as a function of the mosaic spread have been found in the epitaxial films. These maxima in j{sub c} indicate that the magnetic flux lines, in films of structural quality approaching that of single crystals, are insufficiently pinned which results in a decreased critical currentmore » density. T{sub c} increased monotonically with improving crystalline quality and approached a value characteristic of a pure single crystal. A strong correlation between j{sub c} and the density of edge dislocations N{sub D} was found. At the maximum of the critical current density the density of edge dislocations was estimated to be N{sub D}{approximately}1-2 x 10{sup 9}/cm{sup 2}.« less

Correlations between critical current density, j(sub c), critical temperature, T(sub c),and structural quality of Y1B2Cu3O(7-x) thin superconducting films

NASA Technical Reports Server (NTRS)

Chrzanowski, J.; Xing, W. B.; Atlan, D.; Irwin, J. C.; Heinrich, B.; Cragg, R. A.; Zhou, H.; Angus, V.; Habib, F.; Fife, A. A.

1995-01-01

Correlations between critical current density (j(sub c)) critical temperature (T(sub c)) and the density of edge dislocations and nonuniform strain have been observed in YBCO thin films deposited by pulsed laser ablation on (001) LaAlO3 single crystals. Distinct maxima in j(sub c) as a function of the linewidths of the (00 l) Bragg reflections and as a function of the mosaic spread have been found in the epitaxial films. These maxima in j(sub c) indicate that the magnetic flux lines, in films of structural quality approachingthat of single crystals, are insufficiently pinned which results in a decreased critical current density. T(sub c) increased monotonically with improving crystalline quality and approached a value characteristic of a pure single crystal. A strong correlation between j(sub c) and the density of edge dislocations ND was found. At the maximum of the critical current density the density of edge dislocations was estimated to be N(sub D) approximately 1-2 x 10(exp 9)/sq cm.

Effects of heavy-ion irradiation on the microwave surface impedance of (Ba1-x K x )Fe2As2 single crystals

NASA Astrophysics Data System (ADS)

Ghigo, G.; Torsello, D.; Gerbaldo, R.; Gozzelino, L.; Laviano, F.; Tamegai, T.

2018-07-01

The electrodynamic response of Ba1-x K x Fe2As2 single crystals at the microwave frequencies has been investigated by means of a coplanar resonator technique, at different values of non-magnetic disorder introduced into the samples by heavy-ion irradiation. The surface impedance Z s = R s + iX s conforms to the classical skin effect above the critical temperature. Below T c, R s monotonically decreases while X s shows a peak, which evolves as a function of the irradiation fluence. The disorder-dependent Z s (T) curves are analyzed within a two-fluid model, suitably modified to account for a finite quasiparticle fraction at T = 0. The analysis gives, for the unirradiated crystal, quasiparticle relaxation times τ that are in good agreement with previous literature. Smaller τ values are deduced for the disordered crystals, both in the normal and in the superconducting states. The limits of application of the model are discussed.

Mechanical Properties of Shock Treated Aluminium Alloy Al 2024-T4

NASA Astrophysics Data System (ADS)

Joshi, K. D.; Mukhopadhyay, A. K.; Dey, A.; Rav, Amit S.; Biswas, S.; Gupta, Satish C.

2012-07-01

Plate impact experiment has been carried out on Al 2024-T4 alloy using single stage gas gun. The dynamic yield strength and spall strength of Al 2024-T4 sample has been determined to be 0.35 GPa and 1.43 GPa, respectively, from free surface velocity history measured using VISAR. The sample recovered after unloading from peak shock pressure of 4.4 GPa along with an unshocked sample is analyzed for mechanical properties using nano-indentation and scanning electron microscopy (SEM). The nano-indentation measurements reveal that the hardness and Young's modulus for unshocked sample remains unchanged as a function of load (equivalently depth), however, the same for shocked sample decreases monotonically with increase of load up to ~40 mN and on further increase of load it remains unchanged, suggesting the (i) increase in hardness of shock loaded sample; (ii) the increase in hardness is limited to certain depth, which in our case is 845.12 ± 43.16 nm.

Curvature dependence of single-walled carbon nanotubes for SO2 adsorption and oxidation

NASA Astrophysics Data System (ADS)

Chen, Yanqiu; Yin, Shi; Li, Yueli; Cen, Wanglai; Li, Jianjun; Yin, Huaqiang

2017-05-01

Porous carbon-based catalysts showing high catalytic activity for SO2 oxidation to SO3 is often used in flue gas desulfurization. Their catalytic activity has been ascribed in many publications to the microporous structure and the effect of its spatial confinement. First principles method was used to investigate the adsorption and oxidation of SO2 on the inner and outer surface of single-walled carbon nanotubes (SWCNTs) with different diameters. It is interesting to found that there is a direct correlation: the barrier for the oxidation O_SWCNT + SO2 → SO3 + SWCNT monotonically decreases with the increase of SWCNTs' curvature. The oxygen functional located at the inner wall of SWCNTs with small radius is of higher activity for SO2 oxidation, which is extra enhanced by the spatial confinement effects of SWCNTs. These findings can be useful for the development of carbon-based catalysts and provide clues for the optimization and design of porous carbon catalysts.

Axial residual stresses in boron fibers

NASA Technical Reports Server (NTRS)

Behrendt, D. R.

1978-01-01

The axial residual stress distribution as a function of radius was determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diameter fibers were similar, being compressive at the surface and changing monotonically to a region of tensile within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile stress of about 860 mn/sq.m and then decreases to a compressive stress near the tungsten boride core. Data were presented for 203 micron diameter B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102 micron diameter B/W and boron on carbon (b/C) shows that the residual stresses were similar in the outer regions of the fibers, but that large differences near and in the core were observed. The effects of these residual stresses on the fracture of boron fibers were discussed.

Optimal vaccination strategies and rational behaviour in seasonal epidemics.

PubMed

Doutor, Paulo; Rodrigues, Paula; Soares, Maria do Céu; Chalub, Fabio A C C

2016-12-01

We consider a SIRS model with time dependent transmission rate. We assume time dependent vaccination which confers the same immunity as natural infection. We study two types of vaccination strategies: (i) optimal vaccination, in the sense that it minimizes the effort of vaccination in the set of vaccination strategies for which, for any sufficiently small perturbation of the disease free state, the number of infectious individuals is monotonically decreasing; (ii) Nash-equilibria strategies where all individuals simultaneously minimize the joint risk of vaccination versus the risk of the disease. The former case corresponds to an optimal solution for mandatory vaccinations, while the second corresponds to the equilibrium to be expected if vaccination is fully voluntary. We are able to show the existence of both optimal and Nash strategies in a general setting. In general, these strategies will not be functions but Radon measures. For specific forms of the transmission rate, we provide explicit formulas for the optimal and the Nash vaccination strategies.

The effect of transverse wave vector and magnetic fields on resonant tunneling times in double-barrier structures

NASA Astrophysics Data System (ADS)

Wang, Hongmei; Zhang, Yafei; Xu, Huaizhe

2007-01-01

The effect of transverse wave vector and magnetic fields on resonant tunneling times in double-barrier structures, which is significant but has been frequently omitted in previous theoretical methods, has been reported in this paper. The analytical expressions of the longitudinal energies of quasibound levels (LEQBL) and the lifetimes of quasibound levels (LQBL) in symmetrical double-barrier (SDB) structures have been derived as a function of transverse wave vector and longitudinal magnetic fields perpendicular to interfaces. Based on our derived analytical expressions, the LEQBL and LQBL dependence upon transverse wave vector and longitudinal magnetic fields has been explored numerically for a SDB structure. Model calculations show that the LEQBL decrease monotonically and the LQBL shorten with increasing transverse wave vector, and each original LEQBL splits to a series of sub-LEQBL which shift nearly linearly toward the well bottom and the lifetimes of quasibound level series (LQBLS) shorten with increasing Landau-level indices and magnetic fields.

Texture coarseness responsive neurons and their mapping in layer 2–3 of the rat barrel cortex in vivo

PubMed Central

Garion, Liora; Dubin, Uri; Rubin, Yoav; Khateb, Mohamed; Schiller, Yitzhak; Azouz, Rony; Schiller, Jackie

2014-01-01

Texture discrimination is a fundamental function of somatosensory systems, yet the manner by which texture is coded and spatially represented in the barrel cortex are largely unknown. Using in vivo two-photon calcium imaging in the rat barrel cortex during artificial whisking against different surface coarseness or controlled passive whisker vibrations simulating different coarseness, we show that layer 2–3 neurons within barrel boundaries differentially respond to specific texture coarsenesses, while only a minority of neurons responded monotonically with increased or decreased surface coarseness. Neurons with similar preferred texture coarseness were spatially clustered. Multi-contact single unit recordings showed a vertical columnar organization of texture coarseness preference in layer 2–3. These findings indicate that layer 2–3 neurons perform high hierarchical processing of tactile information, with surface coarseness embodied by distinct neuronal subpopulations that are spatially mapped onto the barrel cortex. DOI: http://dx.doi.org/10.7554/eLife.03405.001 PMID:25233151

Computer simulation of a cellular automata model for the immune response in a retrovirus system

NASA Astrophysics Data System (ADS)

Pandey, R. B.

1989-02-01

Immune response in a retrovirus system is modeled by a network of three binary cell elements to take into account some of the main functional features of T4 cells, T8 cells, and viruses. Two different intercell interactions are introduced, one of which leads to three fixed points while the other yields bistable fixed points oscillating between a healthy state and a sick state in a mean field treatment. Evolution of these cells is studied for quenched and annealed random interactions on a simple cubic lattice with a nearest neighbor interaction using inhomogenous cellular automata. Populations of T4 cells and viral cells oscillate together with damping (with constant amplitude) for annealed (quenched) interaction on increasing the value of mixing probability B from zero to a characteristic value B ca ( B cq). For higher B, the average number of T4 cells increases while that of the viral infected cells decreases monotonically on increasing B, suggesting a phase transition at B ca ( B cq).

The landscape of particle production: results from PHOBOS

NASA Astrophysics Data System (ADS)

Steinberg, Peter; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A. H.; Wysłouch, B.; Zhang, J.

2004-08-01

Recent results from the PHOBOS experiment at RHIC are presented, both from Au+Au collisions from the 2001 run and p+p and d+Au collisions from 2003. The centrality dependence of the total charged-particle multiplicity in p+p and d+Au shows features, such as Npart scaling and limiting fragmentation, similar to p+A collisions at lower energies. Multiparticle physics in Au+Au is found to be local in (pseudo)rapidity, both when observed by HBT correlations and by forward-backward pseudorapidity correlations. The shape of elliptic flow in Au+Au, measured over the full range of pseudorapidity, appears to have a very weak centrality dependence. Identified particle ratios in d+Au reactions show little difference between the shape of proton and anti-proton spectra, while the absolute yields show an approximate mT scaling. Finally, results on RdAu as a function of pseudorapidity show that this ratio decreases monotonically with η, even between 0.2 < η < 1.4.

The behavior of nanothermite reaction based on Bi2O3/Al

NASA Astrophysics Data System (ADS)

Wang, L.; Luss, D.; Martirosyan, K. S.

2011-10-01

We studied the impact of aluminum particle size and the thickness of surrounding alumina layer on the dynamic pressure discharge of nanothermite reactions in the Bi2O3/Al system. A pressure discharge from 9 to 13 MPa was generated using as-synthesized Bi2O3 nano-particles produced by combustion synthesis and Al nanoparticles with size from 3 μm to 100 nm. The maximum reaction temperature was measured to be ˜2700 °C. The estimated activation energy of the reaction was 45 kJ/mol. A very large (several orders of magnitude) difference existed between the rate of the pressure pulse release by nanothermite reactions and by thermite reactions with large aluminum particles. The maximum observed pressurization rate was 3200 GPa/s. The time needed to reach the peak pressure was 0.01 ms and 100 ms for aluminum particles with diameter of 100 nm and 70 microns, respectively. The discharge pressure was a monotonic decreasing function of the thickness of the surrounding alumina layer.

Rotational versus alternating hysteresis losses in nonoriented soft magnetic laminations

NASA Astrophysics Data System (ADS)

Fiorillo, F.; Rietto, A. M.

1993-05-01

Rotational and alternating hysteresis losses have been investigated in theory and experiment in nonoriented soft magnetic laminations. Attention has been focused on the dependence of energy loss on peak magnetization Ip. The experiments, performed in a wide induction range (˜2×10-4 T≤Ip≤˜1.6 T), show that the ratio between rotational and alternating energy losses Whr/Wha is a monotonically decreasing function of Ip. A quantitative theoretical investigation is carried out through modeling of the magnetization process under rotating field and its relation to processes under alternating field. Three basic mechanisms of magnetization rotation are considered: linear combination of unidirectional hysteresis loops at low inductions (Rayleigh region), cyclic rearrangement of magnetic domains between different easy directions at intermediate inductions, and coherent spin rotation toward the approach to magnetic saturation. The ensuing predicted behavior of Whr/Wha is found to be in good agreement with the experiments performed in nonoriented low carbon steel and 3% FeSi laminations.

Dynamical Characteristics Common to Neuronal Competition Models

PubMed Central

Shpiro, Asya; Curtu, Rodica; Rinzel, John; Rubin, Nava

2009-01-01

Models implementing neuronal competition by reciprocally inhibitory populations are widely used to characterize bistable phenomena such as binocular rivalry. We find common dynamical behavior in several models of this general type, which differ in their architecture in the form of their gain functions, and in how they implement the slow process that underlies alternating dominance. We focus on examining the effect of the input strength on the rate (and existence) of oscillations. In spite of their differences, all considered models possess similar qualitative features, some of which we report here for the first time. Experimentally, dominance durations have been reported to decrease monotonically with increasing stimulus strength (such as Levelt's “Proposition IV”). The models predict this behavior; however, they also predict that at a lower range of input strength dominance durations increase with increasing stimulus strength. The nonmonotonic dependency of duration on stimulus strength is common to both deterministic and stochastic models. We conclude that additional experimental tests of Levelt's Proposition IV are needed to reconcile models and perception. PMID:17065254

Some Results on Mean Square Error for Factor Score Prediction

ERIC Educational Resources Information Center

Krijnen, Wim P.

2006-01-01

For the confirmatory factor model a series of inequalities is given with respect to the mean square error (MSE) of three main factor score predictors. The eigenvalues of these MSE matrices are a monotonic function of the eigenvalues of the matrix gamma[subscript rho] = theta[superscript 1/2] lambda[subscript rho] 'psi[subscript rho] [superscript…

A Mathematical Model of Bio-Economic Harvesting of a Nonlinear Prey-Predator System

ERIC Educational Resources Information Center

Kar, Tapan Kumar

2006-01-01

The paper reports on studies of the impact of harvesting on a prey-predator system with non-monotonic functional response and intra-specific competition in the predator growth dynamics. The existence of its steady states and their stability are studied using eigenvalue analysis. The possibility of the existence of bionomic equilibria has been…

Using Data Augmentation and Markov Chain Monte Carlo for the Estimation of Unfolding Response Models

ERIC Educational Resources Information Center

Johnson, Matthew S.; Junker, Brian W.

2003-01-01

Unfolding response models, a class of item response theory (IRT) models that assume a unimodal item response function (IRF), are often used for the measurement of attitudes. Verhelst and Verstralen (1993)and Andrich and Luo (1993) independently developed unfolding response models by relating the observed responses to a more common monotone IRT…

Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at √{sNN}=62.4 and 200 GeV

NASA Astrophysics Data System (ADS)

Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Al-Jamel, A.; Alexander, J.; Aoki, K.; Aphecetche, L.; Armendariz, R.; Aronson, S. H.; Asai, J.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Baksay, G.; Baksay, L.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Bathe, S.; Batsouli, S.; Baublis, V.; Bauer, F.; Bazilevsky, A.; Belikov, S.; Bennett, R.; Berdnikov, Y.; Bickley, A. A.; Bjorndal, M. T.; Boissevain, J. G.; Borel, H.; Boyle, K.; Brooks, M. L.; Brown, D. S.; Bucher, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Burward-Hoy, J. M.; Butsyk, S.; Campbell, S.; Chai, J.-S.; Chang, B. S.; Charvet, J.-L.; Chernichenko, S.; Chi, C. Y.; Chiba, J.; Chiu, M.; Choi, I. J.; Chujo, T.; Chung, P.; Churyn, A.; Cianciolo, V.; Cleven, C. R.; Cobigo, Y.; Cole, B. A.; Comets, M. P.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Das, K.; David, G.; Deaton, M. B.; Dehmelt, K.; Delagrange, H.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drachenberg, J. L.; Drapier, O.; Drees, A.; Dubey, A. K.; Durum, A.; Dzhordzhadze, V.; Efremenko, Y. V.; Egdemir, J.; Ellinghaus, F.; Emam, W. S.; Enokizono, A.; En'yo, H.; Espagnon, B.; Esumi, S.; Eyser, K. O.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Forestier, B.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fung, S.-Y.; Fusayasu, T.; Gadrat, S.; Garishvili, I.; Gastineau, F.; Germain, M.; Glenn, A.; Gong, H.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Hachiya, T.; Hadj Henni, A.; Haegemann, C.; Haggerty, J. S.; Hagiwara, M. N.; Hamagaki, H.; Han, R.; Harada, H.; Hartouni, E. P.; Haruna, K.; Harvey, M.; Haslum, E.; Hasuko, K.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Heuser, J. M.; Hiejima, H.; Hill, J. C.; Hobbs, R.; Hohlmann, M.; Holmes, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Hur, M. G.; Ichihara, T.; Iinuma, H.; Imai, K.; Inaba, M.; Inoue, Y.; Isenhower, D.; Isenhower, L.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Jacak, B. V.; Jia, J.; Jin, J.; Jinnouchi, O.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kaneta, M.; Kang, J. H.; Kanou, H.; Kawagishi, T.; Kawall, D.; Kazantsev, A. V.; Kelly, S.; Khanzadeev, A.; Kikuchi, J.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, Y.-S.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kiyomichi, A.; Klay, J.; Klein-Boesing, C.; Kochenda, L.; Kochetkov, V.; Komkov, B.; Konno, M.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kroon, P. J.; Kubart, J.; Kunde, G. J.; Kurihara, N.; Kurita, K.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Le Bornec, Y.; Leckey, S.; Lee, D. M.; Lee, M. K.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Lenzi, B.; Li, X.; Li, X. H.; Lim, H.; Liška, T.; Litvinenko, A.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mao, Y.; Mašek, L.; Masui, H.; Matathias, F.; McCain, M. C.; McCumber, M.; McGaughey, P. L.; Miake, Y.; Mikeš, P.; Miki, K.; Miller, T. E.; Milov, A.; Mioduszewski, S.; Mishra, G. C.; Mishra, M.; Mitchell, J. T.; Mitrovski, M.; Morreale, A.; Morrison, D. P.; Moss, J. M.; Moukhanova, T. V.; Mukhopadhyay, D.; Murata, J.; Nagamiya, S.; Nagata, Y.; Nagle, J. L.; Naglis, M.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Norman, B. E.; Nouicer, R.; Nyanin, A. S.; Nystrand, J.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Ohnishi, H.; Ojha, I. D.; Oka, M.; Okada, K.; Omiwade, O. O.; Oskarsson, A.; Otterlund, I.; Ouchida, M.; Ozawa, K.; Pak, R.; Pal, D.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, J.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pinkenburg, C.; Pisani, R. P.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reuter, M.; Reygers, K.; Riabov, V.; Riabov, Y.; Roche, G.; Romana, A.; Rosati, M.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Rykov, V. L.; Ryu, S. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakata, H.; Samsonov, V.; Sato, H. D.; Sato, S.; Sawada, S.; Seele, J.; Seidl, R.; Semenov, V.; Seto, R.; Sharma, D.; Shea, T. K.; Shein, I.; Shevel, A.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shohjoh, T.; Shoji, K.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, C. P.; Singh, V.; Skutnik, S.; Slunečka, M.; Smith, W. C.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Suire, C.; Sullivan, J. P.; Sziklai, J.; Tabaru, T.; Takagi, S.; Takagui, E. M.; Taketani, A.; Tanaka, K. H.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Taranenko, A.; Tarján, P.; Thomas, T. L.; Todoroki, T.; Togawa, M.; Toia, A.; Tojo, J.; Tomášek, L.; Torii, H.; Towell, R. S.; Tram, V.-N.; Tserruya, I.; Tsuchimoto, Y.; Tuli, S. K.; Tydesjö, H.; Tyurin, N.; Vale, C.; Valle, H.; van Hecke, H. W.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wagner, M.; Walker, D.; Wang, X. R.; Watanabe, Y.; Wessels, J.; White, S. N.; Willis, N.; Winter, D.; Woody, C. L.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yanovich, A.; Yasin, Z.; Ying, J.; Yokkaichi, S.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zaudtke, O.; Zhang, C.; Zhou, S.; Zimányi, J.; Zolin, L.; Phenix Collaboration

2015-09-01

We have studied the dependence of azimuthal anisotropy v2 for inclusive and identified charged hadrons in Au +Au and Cu +Cu collisions on collision energy, species, and centrality. The values of v2 as a function of transverse momentum pT and centrality in Au +Au collisions at √{s NN}=200 and 62.4 GeV are the same within uncertainties. However, in Cu +Cu collisions we observe a decrease in v2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au +Au and Cu +Cu collisions we find that v2 depends both on eccentricity and the number of participants, Npart. We observe that v2 divided by eccentricity (ɛ ) monotonically increases with Npart and scales as Npart1 /3. The Cu +Cu data at 62.4 GeV falls below the other scaled v2 data. For identified hadrons, v2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy K ET=mT-m between 0.1

Surface-state depopulation on small Ag(111) terraces.

PubMed

Morgenstern, Karina; Braun, Kai-Felix; Rieder, Karl-Heinz

2002-11-25

The dependence of the local density of states near the Fermi energy E(F) on the width of terraces T is investigated by tunneling scanning spectroscopy on Ag(111) at 7 K. With decreasing T, the electronic density in the occupied surface state shifts monotonically towards E(F), leading to a depopulation at T=3.2 nm in quantitative agreement with a Fabry-Pérot model. Depopulation coincides with a switch from confinement by terrace modulation to step modulation.

SUPERGRANULATION AS THE LARGEST BUOYANTLY DRIVEN CONVECTIVE SCALE OF THE SUN

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

Cossette, Jean-Francois; Rast, Mark P.

The origin of solar supergranulation remains a mystery. Unlike granulation, the size of which is comparable to both the thickness of the radiative boundary layer and local scale-height in the photosphere, supergranulation does not reflect any obvious length scale of the solar convection zone. Moreover, recent observations of flows in the photosphere using Doppler imaging or correlation or feature tracking show a monotonic decrease in horizontal flow power at scales larger than supergranulation. Both local area and global spherical shell simulations of solar convection by contrast show the opposite, an increase in horizontal flow amplitudes to a low wavenumber. Wemore » examine these disparities and investigate how the solar supergranulation may arise as a consequence of nonlocal heat transport by cool diving plumes. Using three-dimensional anelastic simulations with surface driving, we show that the kinetic energy of the largest convective scales in the upper layers of a stratified domain reflects the depth of transition from strong buoyant driving to adiabatic stratification below caused by the dilution of the granular downflows. This depth is quite shallow because of the rapid increase of the mean density below the photosphere. We interpret the observed monotonic decrease in solar convective power at scales larger than supergranulation to be a consequence of this rapid transition, with the supergranular scale the largest buoyantly driven mode of convection in the Sun.« less

Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

NASA Technical Reports Server (NTRS)

2005-01-01

The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of the loading conditions. In monotonically strained specimens, deformation during the subsequent fatigue loading was mainly confined to the deformation bands initiated during the prior monotonic straining. This can cause dislocations to move more readily along the previously activated deformation bands and to pile up near grain boundaries, eventually making the grain boundaries susceptible to fatigue crack initiation. The mechanisms inferred from the microstructural investigation were extremely valuable in interpreting the influence of prior monotonic straining on the subsequent fatigue life of Inconel 718 superalloy.

Failure Characteristics of Granite Influenced by Sample Height-to-Width Ratios and Intermediate Principal Stress Under True-Triaxial Unloading Conditions

NASA Astrophysics Data System (ADS)

Li, Xibing; Feng, Fan; Li, Diyuan; Du, Kun; Ranjith, P. G.; Rostami, Jamal

2018-05-01

The failure modes and peak unloading strength of a typical hard rock, Miluo granite, with particular attention to the sample height-to-width ratio (between 2 and 0.5), and the intermediate principal stress was investigated using a true-triaxial test system. The experimental results indicate that both sample height-to-width ratios and intermediate principal stress have an impact on the failure modes, peak strength and severity of rockburst in hard rock under true-triaxial unloading conditions. For longer rectangular specimens, the transition of failure mode from shear to slabbing requires higher intermediate principal stress. With the decrease in sample height-to-width ratios, slabbing failure is more likely to occur under the condition of lower intermediate principal stress. For same intermediate principal stress, the peak unloading strength monotonically increases with the decrease in sample height-to-width. However, the peak unloading strength as functions of intermediate principal stress for different types of rock samples (with sample height-to-width ratio of 2, 1 and 0.5) all present the pattern of initial increase, followed by a subsequent decrease. The curves fitted to octahedral shear stress as a function of mean effective stress also validate the applicability of the Mogi-Coulomb failure criterion for all considered rock sizes under true-triaxial unloading conditions, and the corresponding cohesion C and internal friction angle φ are calculated. The severity of strainburst of granite depends on the sample height-to-width ratios and intermediate principal stress. Therefore, different supporting strategies are recommended in deep tunneling projects and mining activities. Moreover, the comparison of test results of different σ 2/ σ 3 also reveals the little influence of minimum principal stress on failure characteristics of granite during the true-triaxial unloading process.

Adaptiveness in monotone pseudo-Boolean optimization and stochastic neural computation.

PubMed

Grossi, Giuliano

2009-08-01

Hopfield neural network (HNN) is a nonlinear computational model successfully applied in finding near-optimal solutions of several difficult combinatorial problems. In many cases, the network energy function is obtained through a learning procedure so that its minima are states falling into a proper subspace (feasible region) of the search space. However, because of the network nonlinearity, a number of undesirable local energy minima emerge from the learning procedure, significantly effecting the network performance. In the neural model analyzed here, we combine both a penalty and a stochastic process in order to enhance the performance of a binary HNN. The penalty strategy allows us to gradually lead the search towards states representing feasible solutions, so avoiding oscillatory behaviors or asymptotically instable convergence. Presence of stochastic dynamics potentially prevents the network to fall into shallow local minima of the energy function, i.e., quite far from global optimum. Hence, for a given fixed network topology, the desired final distribution on the states can be reached by carefully modulating such process. The model uses pseudo-Boolean functions both to express problem constraints and cost function; a combination of these two functions is then interpreted as energy of the neural network. A wide variety of NP-hard problems fall in the class of problems that can be solved by the model at hand, particularly those having a monotonic quadratic pseudo-Boolean function as constraint function. That is, functions easily derived by closed algebraic expressions representing the constraint structure and easy (polynomial time) to maximize. We show the asymptotic convergence properties of this model characterizing its state space distribution at thermal equilibrium in terms of Markov chain and give evidence of its ability to find high quality solutions on benchmarks and randomly generated instances of two specific problems taken from the computational graph theory.

A Lattice-Misfit-Dependent Damage Model for Non-linear Damage Accumulations Under Monotonous Creep in Single Crystal Superalloys

NASA Astrophysics Data System (ADS)

le Graverend, J.-B.

2018-05-01

A lattice-misfit-dependent damage density function is developed to predict the non-linear accumulation of damage when a thermal jump from 1050 °C to 1200 °C is introduced somewhere in the creep life. Furthermore, a phenomenological model aimed at describing the evolution of the constrained lattice misfit during monotonous creep load is also formulated. The response of the lattice-misfit-dependent plasticity-coupled damage model is compared with the experimental results obtained at 140 and 160 MPa on the first generation Ni-based single crystal superalloy MC2. The comparison reveals that the damage model is well suited at 160 MPa and less at 140 MPa because the transfer of stress to the γ' phase occurs for stresses above 150 MPa which leads to larger variations and, therefore, larger effects of the constrained lattice misfit on the lifetime during thermo-mechanical loading.

Nonequilibrium Entropy in a Shock

DOE PAGES

Margolin, Len G.

2017-07-19

In a classic paper, Morduchow and Libby use an analytic solution for the profile of a Navier–Stokes shock to show that the equilibrium thermodynamic entropy has a maximum inside the shock. There is no general nonequilibrium thermodynamic formulation of entropy; the extension of equilibrium theory to nonequililbrium processes is usually made through the assumption of local thermodynamic equilibrium (LTE). However, gas kinetic theory provides a perfectly general formulation of a nonequilibrium entropy in terms of the probability distribution function (PDF) solutions of the Boltzmann equation. In this paper I will evaluate the Boltzmann entropy for the PDF that underlies themore » Navier–Stokes equations and also for the PDF of the Mott–Smith shock solution. I will show that both monotonically increase in the shock. As a result, I will propose a new nonequilibrium thermodynamic entropy and show that it is also monotone and closely approximates the Boltzmann entropy.« less

Using exogenous variables in testing for monotonic trends in hydrologic time series

USGS Publications Warehouse

Alley, William M.

1988-01-01

One approach that has been used in performing a nonparametric test for monotonic trend in a hydrologic time series consists of a two-stage analysis. First, a regression equation is estimated for the variable being tested as a function of an exogenous variable. A nonparametric trend test such as the Kendall test is then performed on the residuals from the equation. By analogy to stagewise regression and through Monte Carlo experiments, it is demonstrated that this approach will tend to underestimate the magnitude of the trend and to result in some loss in power as a result of ignoring the interaction between the exogenous variable and time. An alternative approach, referred to as the adjusted variable Kendall test, is demonstrated to generally have increased statistical power and to provide more reliable estimates of the trend slope. In addition, the utility of including an exogenous variable in a trend test is examined under selected conditions.

Nonequilibrium Entropy in a Shock

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

Margolin, Len G.

In a classic paper, Morduchow and Libby use an analytic solution for the profile of a Navier–Stokes shock to show that the equilibrium thermodynamic entropy has a maximum inside the shock. There is no general nonequilibrium thermodynamic formulation of entropy; the extension of equilibrium theory to nonequililbrium processes is usually made through the assumption of local thermodynamic equilibrium (LTE). However, gas kinetic theory provides a perfectly general formulation of a nonequilibrium entropy in terms of the probability distribution function (PDF) solutions of the Boltzmann equation. In this paper I will evaluate the Boltzmann entropy for the PDF that underlies themore » Navier–Stokes equations and also for the PDF of the Mott–Smith shock solution. I will show that both monotonically increase in the shock. As a result, I will propose a new nonequilibrium thermodynamic entropy and show that it is also monotone and closely approximates the Boltzmann entropy.« less

Fluctuation-driven mechanotransduction regulates mitochondrial-network structure and function

NASA Astrophysics Data System (ADS)

Bartolák-Suki, Erzsébet; Imsirovic, Jasmin; Parameswaran, Harikrishnan; Wellman, Tyler J.; Martinez, Nuria; Allen, Philip G.; Frey, Urs; Suki, Béla

2015-10-01

Cells can be exposed to irregular mechanical fluctuations, such as those arising from changes in blood pressure. Here, we report that ATP production, assessed through changes in mitochondrial membrane potential, is downregulated in vascular smooth muscle cells in culture exposed to monotonous stretch cycles when compared with cells exposed to a variable cyclic stretch that incorporates physiological levels of cycle-by-cycle variability in stretch amplitude. Variable stretch enhances ATP production by increasing the expression of ATP synthase’s catalytic domain, cytochrome c oxidase and its tyrosine phosphorylation, mitofusins and PGC-1α. Such a fluctuation-driven mechanotransduction mechanism is mediated by motor proteins and by the enhancement of microtubule-, actin- and mitochondrial-network complexity. We also show that, in aorta rings isolated from rats, monotonous stretch downregulates--whereas variable stretch maintains--physiological vessel-wall contractility through mitochondrial ATP production. Our results have implications for ATP-dependent and mechanosensitive intracellular processes.

Non-monotonic resonance in a spatially forced Lengyel-Epstein model

DOE PAGES

Haim, Lev; Hagberg, Aric; Meron, Ehud

2015-06-02

Here, we study resonant spatially periodic solutions of the Lengyel-Epstein model modified to describe the chlorine dioxide-iodine-malonic acid reaction under spatially periodic illumination. Using multiple-scale analysis and numerical simulations, we obtain the stability ranges of 2:1 resonant solutions, i.e., solutions with wavenumbers that are exactly half of the forcing wavenumber. We show that the width of resonant wavenumber response is a non-monotonic function of the forcing strength, and diminishes to zero at sufficiently strong forcing. Furthermore, we show that strong forcing may result in a π/2 phase shift of the resonant solutions, and argue that the nonequilibrium Ising-Bloch front bifurcationmore » can be reversed. Finally, we attribute these behaviors to an inherent property of forcing by periodic illumination, namely, the increase of the mean spatial illumination as the forcing amplitude is increased.« less

Fractional Ornstein-Uhlenbeck noise

NASA Astrophysics Data System (ADS)

Fa, Kwok Sau

2018-06-01

Fractional Ornstein-Uhlenbeck noise is considered and investigated. The fractional Ornstein-Uhlenbeck noise may be linked with a supercapacitor driven by the white noise, and its correlation function for the stationary state shows monotonic and oscillatory decays. In the case of the oscillatory behavior the correlation function presents behaviors similar to those of the harmonic noise (harmonic oscillator driven by the white noise). For application, the Langevin equation with the harmonic potential driven by the fractional Ornstein-Uhlenbeck noise is considered; the first two moments and mean energy are investigated.

Quantal Response: Nonparametric Modeling

DTIC Science & Technology

2017-01-01

DATES COVERED (From ‐ To) 4. TITLE AND SUBTITLE    5a. CONTRACT NUMBER  5b. GRANT NUMBER  5c. PROGRAM  ELEMENT  NUMBER 6. AUTHOR(S)    5d...creasing function as P(x) = G ( f (x) ) , where G is a monotone function such as the standard logistic, normal, or Cauchy CDF. Finite -dimensional...examples with dimension k = 5 where various colors distinguish the basis elements . Figure 3 shows logistic response estimates for these 3 basis sets

Tensile behavior and flow stress anisotropy of accumulative roll bonded Cu-Nb nanolaminates

DOE PAGES

Nizolek, Thomas; Beyerlein, Irene J.; Mara, Nathan A.; ...

2016-02-01

The flow stress, ductility, and in-plane anisotropy are evaluated for bulk accumulative roll bonded copper-niobium nanolaminates with layer thicknesses ranging from 1.8 μm to 15 nm. Uniaxial tensile tests conducted parallel to the rolling direction and transverse direction demonstrate that ductility generally decreases with decreasing layer thickness; however, at 30 nm, both high strengths (1200 MPa) and significant ductility (8%) are achieved. The yield strength increases monotonically with decreasing layer thickness, consistent with the Hall-Petch relationship, and significant in-plane flow stress anisotropy is observed. As a result, Taylor polycrystal modeling is used to demonstrate that crystallographic texture is responsible formore » the in-plane anisotropy and that the effects of texture dominate even at nanoscale layer thicknesses.« less

How do people learn from negative evidence? Non-monotonic generalizations and sampling assumptions in inductive reasoning.

PubMed

Voorspoels, Wouter; Navarro, Daniel J; Perfors, Amy; Ransom, Keith; Storms, Gert

2015-09-01

A robust finding in category-based induction tasks is for positive observations to raise the willingness to generalize to other categories while negative observations lower the willingness to generalize. This pattern is referred to as monotonic generalization. Across three experiments we find systematic non-monotonicity effects, in which negative observations raise the willingness to generalize. Experiments 1 and 2 show that this effect emerges in hierarchically structured domains when a negative observation from a different category is added to a positive observation. They also demonstrate that this is related to a specific kind of shift in the reasoner's hypothesis space. Experiment 3 shows that the effect depends on the assumptions that the reasoner makes about how inductive arguments are constructed. Non-monotonic reasoning occurs when people believe the facts were put together by a helpful communicator, but monotonicity is restored when they believe the observations were sampled randomly from the environment. Copyright © 2015 Elsevier Inc. All rights reserved.

The Effect of Dynamic Recrystallization on Monotonic and Cyclic Behaviour of Al-Cu-Mg Alloy.

PubMed

Tomczyk, Adam; Seweryn, Andrzej; Grądzka-Dahlke, Małgorzata

2018-05-23

The paper presents an investigation that was conducted to determine the possibility of the occurrence of the process of dynamic recrystallization in 2024 alloy during monotonic tensile and creep tests at the elevated temperatures of 100 °C, 200 °C, and 300 °C. As-extruded material was subjected to creep process with constant force at elevated temperatures, until two varying degrees of deformation were reached. After cooling at ambient temperature, the pre-deformed material was subjected to monotonic and fatigue tests as well as metallographic analysis. The process of dynamic recrystallization was determined in monotonic tests to occur at low strain rate (0.0015/s) only at the temperature of 300 °C. However, in the creep tests, this process occurred with varying efficiency, both during creep at 200 °C and 300 °C. Dynamic recrystallization was indicated to have a significant influence on the monotonic and cyclic properties of the material.

An Improved Correction for Range Restricted Correlations Under Extreme, Monotonic Quadratic Nonlinearity and Heteroscedasticity.

PubMed

Culpepper, Steven Andrew

2016-06-01

Standardized tests are frequently used for selection decisions, and the validation of test scores remains an important area of research. This paper builds upon prior literature about the effect of nonlinearity and heteroscedasticity on the accuracy of standard formulas for correcting correlations in restricted samples. Existing formulas for direct range restriction require three assumptions: (1) the criterion variable is missing at random; (2) a linear relationship between independent and dependent variables; and (3) constant error variance or homoscedasticity. The results in this paper demonstrate that the standard approach for correcting restricted correlations is severely biased in cases of extreme monotone quadratic nonlinearity and heteroscedasticity. This paper offers at least three significant contributions to the existing literature. First, a method from the econometrics literature is adapted to provide more accurate estimates of unrestricted correlations. Second, derivations establish bounds on the degree of bias attributed to quadratic functions under the assumption of a monotonic relationship between test scores and criterion measurements. New results are presented on the bias associated with using the standard range restriction correction formula, and the results show that the standard correction formula yields estimates of unrestricted correlations that deviate by as much as 0.2 for high to moderate selectivity. Third, Monte Carlo simulation results demonstrate that the new procedure for correcting restricted correlations provides more accurate estimates in the presence of quadratic and heteroscedastic test score and criterion relationships.

OmpF, a nucleotide-sensing nanoprobe, computational evaluation of single channel activities

NASA Astrophysics Data System (ADS)

Abdolvahab, R. H.; Mobasheri, H.; Nikouee, A.; Ejtehadi, M. R.

2016-09-01

The results of highthroughput practical single channel experiments should be formulated and validated by signal analysis approaches to increase the recognition precision of translocating molecules. For this purpose, the activities of the single nano-pore forming protein, OmpF, in the presence of nucleotides were recorded in real time by the voltage clamp technique and used as a means for nucleotide recognition. The results were analyzed based on the permutation entropy of current Time Series (TS), fractality, autocorrelation, structure function, spectral density, and peak fraction to recognize each nucleotide, based on its signature effect on the conductance, gating frequency and voltage sensitivity of channel at different concentrations and membrane potentials. The amplitude and frequency of ion current fluctuation increased in the presence of Adenine more than Cytosine and Thymine in milli-molar (0.5 mM) concentrations. The variance of the current TS at various applied voltages showed a non-monotonic trend whose initial increasing slope in the presence of Thymine changed to a decreasing one in the second phase and was different from that of Adenine and Cytosine; e.g., by increasing the voltage from 40 to 140 mV in the 0.5 mM concentration of Adenine or Cytosine, the variance decreased by one third while for the case of Thymine it was doubled. Moreover, according to the structure function of TS, the fractality of current TS differed as a function of varying membrane potentials (pd) and nucleotide concentrations. Accordingly, the calculated permutation entropy of the TS, validated the biophysical approach defined for the recognition of different nucleotides at various concentrations, pd's and polarities. Thus, the promising outcomes of the combined experimental and theoretical methodologies presented here can be implemented as a complementary means in pore-based nucleotide recognition approaches.

Thermoelectric Properties of LaFePO1-xFx and LaFeAsO1-xFx ---Possibility of the Hidden Mass Enhancement of LaFeAsO1-xFx---

NASA Astrophysics Data System (ADS)

Okuda, Tetsuji; Hirata, Wataru; Takemori, Akira; Suzuki, Shinnosuke; Saijo, Satoshi; Miyasaka, Shigeki; Tajima, Setsuko

2011-04-01

We investigated thermoelectric properties for polycrystalline oxypnictide LaFePO1-xFx and LaFeAsO1-xFx. The temperature (T) and F-doping dependences of resistivity (ρ) and Seebeck coefficient (S) are quite different between these compounds. In contrast to a monotonic T dependence and an absence of large F-doping dependences of ρ and S for LaFePO1-xFx, the S for LaFeAsO1-xFx for 0

Convergence analysis of stochastic hybrid bidirectional associative memory neural networks with delays

NASA Astrophysics Data System (ADS)

Wan, Li; Zhou, Qinghua

2007-10-01

The stability property of stochastic hybrid bidirectional associate memory (BAM) neural networks with discrete delays is considered. Without assuming the symmetry of synaptic connection weights and the monotonicity and differentiability of activation functions, the delay-independent sufficient conditions to guarantee the exponential stability of the equilibrium solution for such networks are given by using the nonnegative semimartingale convergence theorem.

Viscoplastic Model Development with an Eye Toward Characterization

NASA Technical Reports Server (NTRS)

Freed, Alan D.; Walker, Kevin P.

1995-01-01

A viscoplastic theory is developed that reduces analytically to creep theory under steady-state conditions. A viscoplastic model is constructed within this theoretical framework by defining material functions that have close ties to the physics of inelasticity. As a consequence, this model is easily characterized-only steady-state creep data, monotonic stress-strain curves, and saturated stress-strain hysteresis loops are required.

Perception of a Communication Source: An Examination of the Ideal Supervisor and Subordinate within a Military Organization.

ERIC Educational Resources Information Center

Hellweg, Susan A.

A study was designed to examine an underlying assumption regarding the use of the semantic differential in measuring the credibility and homophily of a communicator, namely, that responses to an ideal source position themselves at one extreme end of the scale, reflecting the monotonic function of the instrument such that the highest response…

Parsing Heuristic and Forward Search in First-Graders' Game-Play Behavior

ERIC Educational Resources Information Center

Paz, Luciano; Goldin, Andrea P.; Diuk, Carlos; Sigman, Mariano

2015-01-01

Seventy-three children between 6 and 7 years of age were presented with a problem having ambiguous subgoal ordering. Performance in this task showed reliable fingerprints: (a) a non-monotonic dependence of performance as a function of the distance between the beginning and the end-states of the problem, (b) very high levels of performance when the…

Consensus-Based Formation Control of a Class of Multi-Agent Systems

NASA Technical Reports Server (NTRS)

Joshi, Suresh; Gonzalez, Oscar R.

2014-01-01

This paper presents a consensus-based formation control scheme for autonomous multi-agent systems represented by double integrator dynamics. Assuming that the information graph topology consists of an undirected connected graph, a leader-based consensus-type control law is presented and shown to provide asymptotic formation stability when subjected to piecewise constant formation velocity commands. It is also shown that global asymptotic stability is preserved in the presence of (0, infinity)- sector monotonic non-decreasing actuator nonlinearities.

The response of a linear monostable system and its application in parameters estimation for PSK signals

NASA Astrophysics Data System (ADS)

Duan, Chaowei; Zhan, Yafeng

2016-03-01

The output characteristics of a linear monostable system driven with a periodic signal and an additive white Gaussian noise are studied in this paper. Theoretical analysis shows that the output signal-to-noise ratio (SNR) decreases monotonously with the increasing noise intensity but the output SNR-gain is stable. Inspired by this high SNR-gain phenomenon, this paper applies the linear monostable system in the parameters estimation algorithm for phase shift keying (PSK) signals and improves the estimation performance.

Substituent effects in infrared spectroscopy—VII. Meta and para substituted methanesulphonanilides

NASA Astrophysics Data System (ADS)

Laurence, C.; Berthelot, M.; Lucon, M.; Tsuno, Y.

Substituent effects on the NH frequencies of the conformers of methanesulphonanilides, their cyclic dimers and their hydrogen bonded complexes with acetonitrile have been analysed by means of the Hammet equation. An electron-withdrawing substituent may either increase or decrease ν(NH) in the XC 6H 4NHY series according to the electronic nature of the Y group. This can be explained by the non-monotonic dependence of the NH stretching frequency on the ionic character of the NH bond.

Exact results for the finite time thermodynamic uncertainty relation

NASA Astrophysics Data System (ADS)

Manikandan, Sreekanth K.; Krishnamurthy, Supriya

2018-03-01

We obtain exact results for the recently discovered finite-time thermodynamic uncertainty relation, for the dissipated work W d , in a stochastically driven system with non-Gaussian work statistics, both in the steady state and transient regimes, by obtaining exact expressions for any moment of W d at arbitrary times. The uncertainty function (the Fano factor of W d ) is bounded from below by 2k_BT as expected, for all times τ, in both steady state and transient regimes. The lower bound is reached at τ=0 as well as when certain system parameters vanish (corresponding to an equilibrium state). Surprisingly, we find that the uncertainty function also reaches a constant value at large τ for all the cases we have looked at. For a system starting and remaining in steady state, the uncertainty function increases monotonically, as a function of τ as well as other system parameters, implying that the large τ value is also an upper bound. For the same system in the transient regime, however, we find that the uncertainty function can have a local minimum at an accessible time τm , for a range of parameter values. The large τ value for the uncertainty function is hence not a bound in this case. The non-monotonicity suggests, rather counter-intuitively, that there might be an optimal time for the working of microscopic machines, as well as an optimal configuration in the phase space of parameter values. Our solutions show that the ratios of higher moments of the dissipated work are also bounded from below by 2k_BT . For another model, also solvable by our methods, which never reaches a steady state, the uncertainty function, is in some cases, bounded from below by a value less than 2k_BT .

Beyond stereotypes of adolescent risk taking: Placing the adolescent brain in developmental context☆

PubMed Central

Romer, Daniel; Reyna, Valerie F.; Satterthwaite, Theodore D.

2017-01-01

Recent neuroscience models of adolescent brain development attribute the morbidity and mortality of this period to structural and functional imbalances between more fully developed limbic regions that subserve reward and emotion as opposed to those that enable cognitive control. We challenge this interpretation of adolescent development by distinguishing risk-taking that peaks during adolescence (sensation seeking and impulsive action) from risk taking that declines monotonically from childhood to adulthood (impulsive choice and other decisions under known risk). Sensation seeking is primarily motivated by exploration of the environment under ambiguous risk contexts, while impulsive action, which is likely to be maladaptive, is more characteristic of a subset of youth with weak control over limbic motivation. Risk taking that declines monotonically from childhood to adulthood occurs primarily under conditions of known risks and reflects increases in executive function as well as aversion to risk based on increases in gist-based reasoning. We propose an alternative Lifespan Wisdom Model that highlights the importance of experience gained through exploration during adolescence. We propose, therefore, that brain models that recognize the adaptive roles that cognition and experience play during adolescence provide a more complete and helpful picture of this period of development. PMID:28777995

Thermodynamic Properties of Heusler Fe2-x C ox M n S i

NASA Astrophysics Data System (ADS)

Ito, Masakazu; Furuta, Tatsuya; Kai, Keita; Taira, Atsushi; Onda, Keijiro; Shigeta, Iduru; Hiroi, Masahiko

2017-04-01

We investigated the thermodynamic properties of Heusler compounds Fe2-x C ox m n S i (0.00 ≤ x ≤ 2.00). The specific heats CP(T) for compounds with x ≤ 0.1 exhibit a λ-type anomaly arising from spin rearrangements at TR. With increasing x, TR decreases linearly and vanishes at x ∼ 0.169 . The magnetic entropy, STR, derived from the magnetic specific heat, Cm(T), released at TR decreases by increasing x. This means the canting angle of spins from the [111] direction decreases by the substitution of Fe atoms with Co atoms, based on the magnetic structure model of Fe2MnSi proposed by Miles et al. For compounds with 0.5 ≤ x , CP(T) in the low-T range can be reproduced by Debye T3 law. The electronic specific heat coefficient decreases monotonically with x.

Effect of Severe Plastic Deformation on Structure and Properties of Al-Sc-Ta and Al-Sc-Ti Alloys

NASA Astrophysics Data System (ADS)

Berezina, Alla; Monastyrska, Tetiana; Davydenko, Olexandr; Molebny, Oleh; Polishchuk, Sergey

2017-03-01

The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6-1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH.

New nonlinear optical effect: self-reflection phenomenon due to exciton-biexciton-light interaction in semiconductors

NASA Astrophysics Data System (ADS)

Khadzhi, P. I.; Lyakhomskaya, K. D.; Nadkin, L. Y.; Markov, D. A.

2002-05-01

The characteristic peculiarities of the self-reflection of a strong electromagnetic wave in a system of coherent excitons and biexcitons due to the exciton-photon interaction and optical exciton-biexciton conversion in semiconductors were investigated as one of the manifestations of nonlinear optical Stark-effect. It was found that a monotonously decreasing standing wave with an exponential decreasing spatial tail is formed in the semiconductor. Under the action of the field of a strong pulse, an optically homogeneous medium is converted, into the medium with distributed feedback. The appearance of the spatially separated narrow pears of the reflective index, extinction and reflection coefficients is predicted.

Well-behaved relativistic charged super-dense star models

NASA Astrophysics Data System (ADS)

Faruqi, Shahab; Pant, Neeraj

2012-10-01

A new class of charged super-dense star models is obtained by using an electric intensity, which involves a parameter, K. The metric describing the model shares its metric potential g 44 with that of Durgapal's fourth solution (J. Phys. A, Math. Gen. 15:2637, 1982). The pressure-free surface is kept at the density ρ b =2×1014 g/cm3 and joins smoothly with the Reissner-Nordstrom solution. The charge analogues are well-behaved for a wide range, 0≤ K≤59, with the optimum value of X=0.264 i.e. the pressure, density, pressure-density ratio and velocity of sound are monotonically decreasing and the electric intensity is monotonically increasing in nature for the given range of the parameter K. The maximum mass and the corresponding radius occupied by the neutral solution are 4.22 M Θ and 20 km, respectively for X=0.264. For the charged solution, the maximum mass and radius are defined by the expressions M≈(0.0059 K+4.22) M Θ and r b ≈-0.021464 K+20 km respectively.

The Monotonic Lagrangian Grid for Fast Air-Traffic Evaluation

NASA Technical Reports Server (NTRS)

Alexandrov, Natalia; Kaplan, Carolyn; Oran, Elaine; Boris, Jay

2010-01-01

This paper describes the continued development of a dynamic air-traffic model, ATMLG, intended for rapid evaluation of rules and methods to control and optimize transport systems. The underlying data structure is based on the Monotonic Lagrangian Grid (MLG), which is used for sorting and ordering positions and other data needed to describe N moving bodies, and their interactions. In ATMLG, the MLG is combined with algorithms for collision avoidance and updating aircraft trajectories. Aircraft that are close to each other in physical space are always near neighbors in the MLG data arrays, resulting in a fast nearest-neighbor interaction algorithm that scales as N. In this paper, we use ATMLG to examine how the ability to maintain a required separation between aircraft decreases as the number of aircraft in the volume increases. This requires keeping track of the primary and subsequent collision avoidance maneuvers necessary to maintain a five mile separation distance between all aircraft. Simulation results show that the number of collision avoidance moves increases exponentially with the number of aircraft in the volume.

Melting phenomena: effect of composition for 55-atom Ag-Pd bimetallic clusters.

PubMed

Cheng, Daojian; Wang, Wenchuan; Huang, Shiping

2008-05-14

Understanding the composition effect on the melting processes of bimetallic clusters is important for their applications. Here, we report the relationship between the melting point and the metal composition for the 55-atom icosahedral Ag-Pd bimetallic clusters by canonical Monte Carlo simulations, using the second-moment approximation of the tight-binding potentials (TB-SMA) for the metal-metal interactions. Abnormal melting phenomena for the systems of interest are found. Our simulation results reveal that the dependence of the melting point on the composition is not a monotonic change, but experiences three different stages. The melting temperatures of the Ag-Pd bimetallic clusters increase monotonically with the concentration of the Ag atoms first. Then, they reach a plateau presenting almost a constant value. Finally, they decrease sharply at a specific composition. The main reason for this change can be explained in terms of the relative stability of the Ag-Pd bimetallic clusters at different compositions. The results suggest that the more stable the cluster, the higher the melting point for the 55-atom icosahedral Ag-Pd bimetallic clusters at different compositions.

Complementary rare earth element patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the earth

NASA Technical Reports Server (NTRS)

Ma, M.-S.; Schmitt, R. A.; Laul, J. C.

1982-01-01

Abundances of major, minor, and trace elements are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare earth element (REE) abundances of ALHA 77005 reveal a unique chondritic normalized pattern; that is, the REEs are nearly unfractionated from La to Pr at approximately 1.0X chondrites, monotonically increased from Pr to Gd at approximately 3.4X with no Eu anomaly, nearly unfractionated from Gd and Ho and monotonically decreased from Ho to Lu at approximately 2.2X. It is noted that this unique REE pattern of ALHA 77005 can be modeled by a melting process involving a continuous melting and progressive partial removal of melt from a light REE enriched source material. In a model of this type, ALHA 77005 could represent either a crystallized cumulate from such a melt or the residual source material. Calculations show that the parent liquids for the shergottites could also be derived from a light REE enriched source material similar to that for ALHA 77005.

Efficient Variable Selection Method for Exposure Variables on Binary Data

NASA Astrophysics Data System (ADS)

Ohno, Manabu; Tarumi, Tomoyuki

In this paper, we propose a new variable selection method for "robust" exposure variables. We define "robust" as property that the same variable can select among original data and perturbed data. There are few studies of effective for the selection method. The problem that selects exposure variables is almost the same as a problem that extracts correlation rules without robustness. [Brin 97] is suggested that correlation rules are possible to extract efficiently using chi-squared statistic of contingency table having monotone property on binary data. But the chi-squared value does not have monotone property, so it's is easy to judge the method to be not independent with an increase in the dimension though the variable set is completely independent, and the method is not usable in variable selection for robust exposure variables. We assume anti-monotone property for independent variables to select robust independent variables and use the apriori algorithm for it. The apriori algorithm is one of the algorithms which find association rules from the market basket data. The algorithm use anti-monotone property on the support which is defined by association rules. But independent property does not completely have anti-monotone property on the AIC of independent probability model, but the tendency to have anti-monotone property is strong. Therefore, selected variables with anti-monotone property on the AIC have robustness. Our method judges whether a certain variable is exposure variable for the independent variable using previous comparison of the AIC. Our numerical experiments show that our method can select robust exposure variables efficiently and precisely.

Kink dynamics in a parametric Φ 6 system: a model with controllably many internal modes

DOE PAGES

Demirkaya, A.; Decker, R.; Kevrekidis, P. G.; ...

2017-12-14

We explore a variant of the Φ 6 model originally proposed in Phys. Rev.D 12 (1975) 1606 as a prototypical, so-called, “bag” model in which domain walls play the role of quarks within hadrons. We examine the steady state of the model, namely an apparent bound state of two kink structures. We explore its linearization, and we find that, as a function of a parameter controlling the curvature of the potential, an effectively arbitrary number of internal modes may arise in the point spectrum of the linearization about the domain wall profile. We explore some of the key characteristics ofmore » kink-antikink collisions, such as the critical velocity and the multi-bounce windows, and how they depend on the principal parameter of the model. We find that the critical velocity exhibits a non-monotonic dependence on the parameter controlling the curvature of the potential. For the multi-bounce windows, we find that their range and complexity decrease as the relevant parameter decreases (and as the number of internal modes in the model increases). We use a modified collective coordinates method [in the spirit of recent works such as Phys. Rev.D 94 (2016) 085008] in order to capture the relevant phenomenology in a semi-analytical manner.« less

Predicting the effect of urban noise on the active space of avian vocal signals.

PubMed

Parris, Kirsten M; McCarthy, Michael A

2013-10-01

Urbanization changes the physical environment of nonhuman species but also markedly changes their acoustic environment. Urban noise interferes with acoustic communication in a range of animals, including birds, with potentially profound impacts on fitness. However, a mechanistic theory to predict which species of birds will be most affected by urban noise is lacking. We develop a mathematical model to predict the decrease in the active space of avian vocal signals after moving from quiet forest habitats to noisy urban habitats. We find that the magnitude of the decrease is largely a function of signal frequency. However, this relationship is not monotonic. A metaregression of observed increases in the frequency of birdsong in urban noise supports the model's predictions for signals with frequencies between 1.5 and 4 kHz. Using results of the metaregression and the model described above, we show that the expected gain in active space following observed frequency shifts is up to 12% and greatest for birds with signals at the lower end of this frequency range. Our generally applicable model, along with three predictions regarding the behavioral and population-level responses of birds to urban noise, represents an important step toward a theory of acoustic communication in urban habitats.

Structure and dynamics of water near the interface with oligo(ethylene oxide) self-assembled monolayers

NASA Astrophysics Data System (ADS)

Ismail, Ahmed E.; Grest, Gary S.; Stevens, Mark J.

2007-03-01

Oligo(ethylene oxide) self-assembled monolayers (OEO SAM's) deposited on Au are the prototypical materials used to study protein resistance. Recently, protein resistance has been shown to vary as a function of surface coverage and to be maximal at about two-thirds coverage, not complete coverage. We use molecular dynamics simulations to study the nature of the interface between water and the OEO SAM for a range of SAM coverages. As SAM coverage decreases, the amount of water within the OEO monolayer increases monotonically; however, the penetration depth of the water shows a maximum near the experimentally-found maximal coverage. As the water content increases, the SAM-water mixture becomes harder to distinguish from bulk water. Since the oxygen atoms of OEO are hydrogen bond acceptors, a hydrogen bond network forms within the SAM-water mixture. The water molecules diffuse freely within the monolayer and exchange with the bulk water. Because the monolayer becomes increasingly like bulk water as the coverage decreases, proteins stay in their bulk soluble conformation and do not adsorb. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract No. DE-AC04-94AL85000.

Kink dynamics in a parametric Φ 6 system: a model with controllably many internal modes

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

Demirkaya, A.; Decker, R.; Kevrekidis, P. G.

We explore a variant of the Φ 6 model originally proposed in Phys. Rev.D 12 (1975) 1606 as a prototypical, so-called, “bag” model in which domain walls play the role of quarks within hadrons. We examine the steady state of the model, namely an apparent bound state of two kink structures. We explore its linearization, and we find that, as a function of a parameter controlling the curvature of the potential, an effectively arbitrary number of internal modes may arise in the point spectrum of the linearization about the domain wall profile. We explore some of the key characteristics ofmore » kink-antikink collisions, such as the critical velocity and the multi-bounce windows, and how they depend on the principal parameter of the model. We find that the critical velocity exhibits a non-monotonic dependence on the parameter controlling the curvature of the potential. For the multi-bounce windows, we find that their range and complexity decrease as the relevant parameter decreases (and as the number of internal modes in the model increases). We use a modified collective coordinates method [in the spirit of recent works such as Phys. Rev.D 94 (2016) 085008] in order to capture the relevant phenomenology in a semi-analytical manner.« less

Kink dynamics in a parametric ϕ 6 system: a model with controllably many internal modes

NASA Astrophysics Data System (ADS)

Demirkaya, A.; Decker, R.; Kevrekidis, P. G.; Christov, I. C.; Saxena, A.

2017-12-01

We explore a variant of the ϕ 6 model originally proposed in Phys. Rev. D 12 (1975) 1606 as a prototypical, so-called, "bag" model in which domain walls play the role of quarks within hadrons. We examine the steady state of the model, namely an apparent bound state of two kink structures. We explore its linearization, and we find that, as a function of a parameter controlling the curvature of the potential, an effectively arbitrary number of internal modes may arise in the point spectrum of the linearization about the domain wall profile. We explore some of the key characteristics of kink-antikink collisions, such as the critical velocity and the multi-bounce windows, and how they depend on the principal parameter of the model. We find that the critical velocity exhibits a non-monotonic dependence on the parameter controlling the curvature of the potential. For the multi-bounce windows, we find that their range and complexity decrease as the relevant parameter decreases (and as the number of internal modes in the model increases). We use a modified collective coordinates method [in the spirit of recent works such as Phys. Rev. D 94 (2016) 085008] in order to capture the relevant phenomenology in a semi-analytical manner.

Quantifying the effect of electric current on cell adhesion studied by single-cell force spectroscopy.

PubMed

Jaatinen, Leena; Young, Eleanore; Hyttinen, Jari; Vörös, János; Zambelli, Tomaso; Demkó, László

2016-03-20

This study presents the effect of external electric current on the cell adhesive and mechanical properties of the C2C12 mouse myoblast cell line. Changes in cell morphology, viability, cytoskeleton, and focal adhesion structure were studied by standard staining protocols, while single-cell force spectroscopy based on the fluidic force microscopy technology provided a rapid, serial quantification and detailed analysis of cell adhesion and its dynamics. The setup allowed measurements of adhesion forces up to the μN range, and total detachment distances over 40 μm. Force-distance curves have been fitted with a simple elastic model including a cell detachment protocol in order to estimate the Young's modulus of the cells, as well as to reveal changes in the dynamic properties as functions of the applied current dose. While the cell spreading area decreased monotonously with increasing current doses, small current doses resulted only in differences related to cell elasticity. Current doses above 11 As/m(2), however, initiated more drastic changes in cell morphology, viability, cellular structure, as well as in properties related to cell adhesion. The observed differences, eventually leading to cell death toward higher doses, might originate from both the decrease in pH and the generation of reactive oxygen species.

Performance Analysis of GaN Capping Layer Thickness on GaN/AlGaN/GaN High Electron Mobility Transistors.

PubMed

Sharma, N; Periasamy, C; Chaturvedi, N

2018-07-01

In this paper, we present an investigation of the impact of GaN capping layer and AlGaN layer thickness on the two-dimensional (2D)-electron mobility and the carrier concentration which was formed close to the AlGaN/GaN buffer layer for Al0.25Ga0.75N/GaN and GaN/Al0.25Ga0.75N/GaN heterostructures deposited on sapphire substrates. The results of our analysis clearly indicate that expanding the GaN capping layer thickness from 1 nm to 100 nm prompts an increment in the electron concentration at hetero interface. As consequence of which drain current was additionally increments with GaN cap layer thicknesses, and eventually saturates at approximately 1.85 A/mm for capping layer thickness greater than 40 nm. Interestingly, for the same structure, the 2D-electron mobility, decrease monotonically with GaN capping layer thickness, and saturate at approximately 830 cm2/Vs for capping layer thickness greater than 50 nm. A device with a GaN cap layer didn't exhibit gate leakage current. Furthermore, it was observed that the carrier concentration was first decrease 1.03 × 1019/cm3 to 6.65 × 1018/cm3 with AlGaN Layer thickness from 5 to 10 nm and after that it increases with the AlGaN layer thickness from 10 to 30 nm. The same trend was followed for electric field distributions. Electron mobility decreases monotonically with AlGaN layer thickness. Highest electron mobility 1354 cm2/Vs were recorded for the AlGaN layer thickness of 5 nm. Results obtained are in good agreement with published experimental data.

Frictional Torque Reduction in Taylor-Couette Flows with Riblet-Textured Rotors

NASA Astrophysics Data System (ADS)

Raayai, Shabnam; McKinley, Gareth

2017-11-01

Inspired by the riblets on the denticles of fast swimming shark species, periodic surface microtextures of different shapes have been studied under laminar and turbulent flow conditions to understand their drag reduction mechanism and to offer guides for designing optimized low-friction bio-inspired surfaces. Various reports over the past four decades have suggested that riblet surfaces can reduce the frictional drag force in high Reynolds number laminar and turbulent flow regimes. Here, we investigate the effect of streamwise riblets on torque reduction in steady flow between concentric cylinders, known as Taylor-Couette Flow. Using 3D printed riblet-textured rotors and a custom-built Taylor-Couette cell which can be mounted on a rheometer we measure the torque on the inner rotor as a function of three different dimensionless parameters; the Reynolds number of the flow, the sharpness of the riblets, and the size of the riblets with respect to the scale of the Taylor-Couette cell. Our experimental results in the laminar viscous flow regime show a reduction in torque up to 10% over a wide range of Reynolds numbers, that is a non-monotonic function of the aspect ratio and independent of Re. However, after transition to the Taylor vortex regime, the modification in torque becomes a function of the Reynolds number, while remaining a non-monotonic function of the aspect ratio. Using finite volume modelling of the geometry we discuss the changes in the Taylor-Couette flow in presence of the riblets compared to the case of smooth rotors and the resulting torque reduction as a function of the parameter space defined above.

Monotonicity preserving splines using rational cubic Timmer interpolation

NASA Astrophysics Data System (ADS)

Zakaria, Wan Zafira Ezza Wan; Alimin, Nur Safiyah; Ali, Jamaludin Md

2017-08-01

In scientific application and Computer Aided Design (CAD), users usually need to generate a spline passing through a given set of data, which preserves certain shape properties of the data such as positivity, monotonicity or convexity. The required curve has to be a smooth shape-preserving interpolant. In this paper a rational cubic spline in Timmer representation is developed to generate interpolant that preserves monotonicity with visually pleasing curve. To control the shape of the interpolant three parameters are introduced. The shape parameters in the description of the rational cubic interpolant are subjected to monotonicity constrained. The necessary and sufficient conditions of the rational cubic interpolant are derived and visually the proposed rational cubic Timmer interpolant gives very pleasing results.

Seeing the trees for the forest: Nitrogen deposition alters tree growth and survival across the northeastern U.S., responses vary by species.

NASA Astrophysics Data System (ADS)

Thomas, R. Q.; Canham, C. D.; Weathers, K. C.; Goodale, C. L.

2008-12-01

Assessments of regional forest carbon (C) balance have long speculated a role for atmospheric nitrogen (N) deposition. To date, however, evidence for an N effect has been restricted to plot-level fertilization and 15N experiments, biogeochemical modeling studies, and recent and controversial correlations between nitrogen deposition and C balance across 20 intensive C monitoring sites. These studies have yielded widely varying conclusions on the magnitude and even the direction of response (positive or negative effects on C storage). We assessed the effects of N deposition on forest growth and survival using forest inventory data from > 160,000 trees, spanning a 19-state region of the northeastern United States, and estimates of total (wet and plot-specific dry) inorganic N inputs (N deposition to the plots ranged from 3.2 to 11 kg N ha-1 y-1). The growth rates of 14 of the region's 24 most common tree species responded to N deposition. Nine species showed a monotonic increase in aboveground growth rates across the range of N deposition and some of these species experienced a doubling of growth rates. Four species showed humped-shaped responses. A single species, Pinus resinosa (red pine), showed a monotonic decline in growth across the range of deposition. Species responsiveness to N deposition increased with mean growth rate of the species. In the analysis of survival, 13 of the 24 species responded to N: eight species showed a monotonic decrease, 3 showed a monotonic increase and 1 showed a humped-shape response in survival. The stand-level analysis showed a distinctly humped-shaped relationship between N deposition and aboveground C increment, peaking at 6 kg N ha-1 yr-1, which can likely be explained by the distribution of species and their individual growth and mortality responses. Overall, our data suggest that moderate levels of N deposition have enhanced aboveground C accumulation in temperate forests of the northeastern U.S., but the shape and trajectory of the response is species-specific.

Influence of niobium doping in hierarchically organized titania nanostructure on performance of dye-sensitized solar cells.

PubMed

Park, Jong Hoon; Noh, Jun Hong; Han, Byung Suh; Shin, Seong Sik; Park, Ik Jae; Kim, Dong Hoe; Hong, Kug Sun

2012-06-01

Niobium doped hierarchically organized TiO2 nanostructures composed of 20 nm size anatase nanocrystals were synthesized using pulsed laser deposition (PLD). The Nb doping concentration could be facilely controlled by adjusting the concentration of Nb in target materials. We could investigate the influence of Nb doping in the TiO2 photoelectrode on the cell performance of dye-sensitized solar cells (DSSCs) by the exclusion of morphological effects using the prepared Nb-doped TiO2 anostructures. We found no significant change in short circuit current density (Jsc) as a function of Nb doping concentration. However, open circuit voltage (Voc) and fill factor (FF) monotonously decrease with increasing Nb concentration. Dark current characteristics of the DSSCs reveal that the decrease in Voc and FF is attributed to the decrease in shunt resistance due to the increase in conductivity TiO2 by Nb doping. However, electrochemical impedance spectra (EIS) analysis at open circuit condition under illumination showed that the resistance at the TiO2/dye/electrolyte interface increases with Nb concentration, revealing that Nb doping suppress the charge recombination at the interface. In addition, electron life time obtained using characteristic frequency in Bode plot increases from 14 msec to 56 msec with increasing Nb concentration from 0 to 1.2 at%. This implies that the improved light harvesting can be achieved by increasing diffusion length through Nb-doping in the conventional TiO2 photoelectrode.

Effects of voice-sparing cricotracheal resection on phonation in women.

PubMed

Tanner, Kristine; Dromey, Christopher; Berardi, Mark L; Mattei, Lisa M; Pierce, Jenny L; Wisco, Jonathan J; Hunter, Eric J; Smith, Marshall E

2017-09-01

Individuals with idiopathic subglottic stenosis (SGS) are at risk for voice disorders prior to and following surgical management. This study examined the nature and severity of voice disorders in patients with SGS before and after a revised cricotracheal resection (CTR) procedure designed to minimize adverse effects on voice function. Eleven women with idiopathic SGS provided presurgical and postsurgical audio recordings. Voice Handicap Index (VHI) scores were also collected. Cepstral, signal-to-noise, periodicity, and fundamental frequency (F 0 ) analyses were undertaken for connected speech and sustained vowel samples. Listeners made auditory-perceptual ratings of overall quality and monotonicity. Paired samples statistical analyses revealed that mean F 0 decreased from 215 Hz (standard deviation [SD] = 40 Hz) to 201 Hz (SD = 65 Hz) following surgery. In general, VHI scores decreased after surgery. Voice disorder severity based on the Cepstral Spectral Index of Dysphonia (KayPentax, Montvale, NJ) for sustained vowels decreased (improved) from 41 (SD = 41) to 25 (SD = 21) points; no change was observed for connected speech. Semitone SD (2.2 semitones) did not change from pre- to posttreatment. Auditory-perceptual ratings demonstrated similar results. These preliminary results indicate that this revised CTR procedure is promising in minimizing adverse voice effects while offering a longer-term surgical outcome for SGS. Further research is needed to determine causal factors for pretreatment voice disorders, as well as to optimize treatments in this population. 4. Laryngoscope, 127:2085-2092, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Effect of Severe Plastic Deformation on Structure and Properties of Al-Sc-Ta and Al-Sc-Ti Alloys.

PubMed

Berezina, Alla; Monastyrska, Tetiana; Davydenko, Olexandr; Molebny, Oleh; Polishchuk, Sergey

2017-12-01

The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6-1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH.

Acute pesticide poisoning in the U.S. retail industry, 1998-2004.

PubMed

Calvert, Geoffrey M; Petersen, Ann M; Sievert, Jennifer; Mehler, Louise N; Das, Rupali; Harter, Lucy C; Romioli, Cinzia; Becker, Alan; Ball, Cynthia; Male, Dorilee; Schwartz, Abby; Lackovic, Michelle

2007-01-01

This study was conducted to describe the national magnitude and characteristics of acute pesticide poisoning among workers and customers in retail establishments. Analyses included retail employees 15-64 years of age and customers with acute pesticide poisoning identified from the Sentinel Event Notification System for Occupational Risks-Pesticides (SENSOR-Pesticides) and California Department of Pesticide Regulation from 1998 to 2004. Pesticide poisoning incidence rates and incidence rate ratios (IRR) were calculated. A total of 325 cases of acute pesticide poisoning were identified. Of these cases, 287 (88%) were retail employees and 38 (12%) were customers. Overall, retail employees had a significantly lower acute pesticide poisoning incidence rate compared with non-agricultural, non-retail employees (IRR=0.53; 95% confidence interval 0.47, 0.59). However, significantly elevated pesticide poisoning incidence rates were observed for four retail occupations (janitors, stock handlers/baggers, bakery/deli clerks, and shipping/receiving handlers). In addition, workers employed in two retail industry sectors (farm supply stores and hardware stores) had significantly elevated acute pesticide poisoning incidence rates. Incidence rates among the retail employees demonstrated a quadratic trend, monotonically decreasing from 1998 to 2000 and monotonically increasing from 2000 to 2003. The rates appear to have leveled off in 2003 and 2004. Preventive measures to decrease acute pesticide poisoning incidence in the retail sector include adoption of unbreakable and tear-resistant container requirements, increased utilization of integrated pest management strategies, and advisement to store managers, employees, and customers about poisoning prevention.

Full orbit computations of ripple-induced fusion {alpha}-particle losses from burning tokamak plasmas

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

McClements, K.G.

A full orbit code is used to compute collisionless losses of fusion {alpha} particles from three proposed burning plasma tokamaks: the International Tokamak Experimental Reactor (ITER); a spherical tokamak power plant (STPP) [T. C. Hender, A. Bond, J. Edwards, P. J. Karditsas, K. G. McClements, J. Mustoe, D. V. Sherwood, G. M. Voss, and H. R. Wilson, Fusion Eng. Des. 48, 255 (2000)]; and a spherical tokamak components test facility (CTF) [H. R. Wilson, G. M. Voss, R. J. Akers, L. Appel, A. Dnestrovskij, O. Keating, T. C. Hender, M. J. Hole, G. Huysmans, A. Kirk, P. J. Knight, M.more » Loughlin, K. G. McClements, M. R. O'Brien, and D. Yu. Sychugov, Proceedings of the 20th IAEA Fusion Energy Conference, Invited Paper FT/3-1Ra]. It has been suggested that {alpha} particle transport could be enhanced due to cyclotron resonance with the toroidal magnetic field ripple. However, calculations for inductive operation in ITER yield a loss rate that appears to be broadly consistent with the predictions of guiding center theory, falling monotonically as the number of toroidal field coils N is increased (and hence the ripple amplitude is decreased). For STPP and CTF the loss rate does not decrease monotonically with N, but collisionless losses are generally low in absolute terms. As in the case of ITER, there is no evidence that finite Larmor radius effects would seriously degrade fusion {alpha}-particle confinement.« less

Never judge a black hole by its area

NASA Astrophysics Data System (ADS)

Ong, Yen Chin

2015-04-01

Christodoulou and Rovelli have shown that black holes have large interiors that grow asymptotically linearly in advanced time, and speculated that this may be relevant to the information loss paradox. We show that there is no simple relation between the interior volume of an arbitrary black hole and its horizon area. That is, the volume enclosed is not necessarily a monotonically increasing function of the surface area.

Rigidity sensing explained by active matter theory.

PubMed

Marcq, Philippe; Yoshinaga, Natsuhiko; Prost, Jacques

2011-09-21

The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. We rationalize this observation using active matter theory, and propose that adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Spatial scaling patterns and functional redundancies in a changing boreal lake landscape

USGS Publications Warehouse

Angeler, David G.; Allen, Craig R.; Uden, Daniel R.; Johnson, Richard K.

2015-01-01

Global transformations extend beyond local habitats; therefore, larger-scale approaches are needed to assess community-level responses and resilience to unfolding environmental changes. Using longterm data (1996–2011), we evaluated spatial patterns and functional redundancies in the littoral invertebrate communities of 85 Swedish lakes, with the objective of assessing their potential resilience to environmental change at regional scales (that is, spatial resilience). Multivariate spatial modeling was used to differentiate groups of invertebrate species exhibiting spatial patterns in composition and abundance (that is, deterministic species) from those lacking spatial patterns (that is, stochastic species). We then determined the functional feeding attributes of the deterministic and stochastic invertebrate species, to infer resilience. Between one and three distinct spatial patterns in invertebrate composition and abundance were identified in approximately one-third of the species; the remainder were stochastic. We observed substantial differences in metrics between deterministic and stochastic species. Functional richness and diversity decreased over time in the deterministic group, suggesting a loss of resilience in regional invertebrate communities. However, taxon richness and redundancy increased monotonically in the stochastic group, indicating the capacity of regional invertebrate communities to adapt to change. Our results suggest that a refined picture of spatial resilience emerges if patterns of both the deterministic and stochastic species are accounted for. Spatially extensive monitoring may help increase our mechanistic understanding of community-level responses and resilience to regional environmental change, insights that are critical for developing management and conservation agendas in this current period of rapid environmental transformation.

Two-component Jaffe models with a central black hole - I. The spherical case

NASA Astrophysics Data System (ADS)

Ciotti, Luca; Ziaee Lorzad, Azadeh

2018-02-01

Dynamical properties of spherically symmetric galaxy models where both the stellar and total mass density distributions are described by the Jaffe (1983) profile (with different scalelengths and masses) are presented. The orbital structure of the stellar component is described by Osipkov-Merritt anisotropy, and a black hole (BH) is added at the centre of the galaxy; the dark matter halo is isotropic. First, the conditions required to have a nowhere negative and monotonically decreasing dark matter halo density profile are derived. We then show that the phase-space distribution function can be recovered by using the Lambert-Euler W function, while in absence of the central BH only elementary functions appears in the integrand of the inversion formula. The minimum value of the anisotropy radius for consistency is derived in terms of the galaxy parameters. The Jeans equations for the stellar component are solved analytically, and the projected velocity dispersion at the centre and at large radii are also obtained analytically for generic values of the anisotropy radius. Finally, the relevant global quantities entering the Virial Theorem are computed analytically, and the fiducial anisotropy limit required to prevent the onset of Radial Orbit Instability is determined as a function of the galaxy parameters. The presented models, even though highly idealized, represent a substantial generalization of the models presented in Ciotti, and can be useful as starting point for more advanced modelling, the dynamics and the mass distribution of elliptical galaxies.

Transformation-invariant and nonparametric monotone smooth estimation of ROC curves.

PubMed

Du, Pang; Tang, Liansheng

2009-01-30

When a new diagnostic test is developed, it is of interest to evaluate its accuracy in distinguishing diseased subjects from non-diseased subjects. The accuracy of the test is often evaluated by receiver operating characteristic (ROC) curves. Smooth ROC estimates are often preferable for continuous test results when the underlying ROC curves are in fact continuous. Nonparametric and parametric methods have been proposed by various authors to obtain smooth ROC curve estimates. However, there are certain drawbacks with the existing methods. Parametric methods need specific model assumptions. Nonparametric methods do not always satisfy the inherent properties of the ROC curves, such as monotonicity and transformation invariance. In this paper we propose a monotone spline approach to obtain smooth monotone ROC curves. Our method ensures important inherent properties of the underlying ROC curves, which include monotonicity, transformation invariance, and boundary constraints. We compare the finite sample performance of the newly proposed ROC method with other ROC smoothing methods in large-scale simulation studies. We illustrate our method through a real life example. Copyright (c) 2008 John Wiley & Sons, Ltd.

Decompositions of large-scale biological systems based on dynamical properties.

PubMed

Soranzo, Nicola; Ramezani, Fahimeh; Iacono, Giovanni; Altafini, Claudio

2012-01-01

Given a large-scale biological network represented as an influence graph, in this article we investigate possible decompositions of the network aimed at highlighting specific dynamical properties. The first decomposition we study consists in finding a maximal directed acyclic subgraph of the network, which dynamically corresponds to searching for a maximal open-loop subsystem of the given system. Another dynamical property investigated is strong monotonicity. We propose two methods to deal with this property, both aimed at decomposing the system into strongly monotone subsystems, but with different structural characteristics: one method tends to produce a single large strongly monotone component, while the other typically generates a set of smaller disjoint strongly monotone subsystems. Original heuristics for the methods investigated are described in the article. altafini@sissa.it

Comparison of Mode II and III Monotonic and Fatigue Delamination Onset Behavior for Carbon/Toughened Epoxy Composites

NASA Technical Reports Server (NTRS)

Li, Jian; OBrien, T. Kevin; Lee, Shaw Ming

1997-01-01

Monotonic and fatigue tests were performed to compare the Mode II and III interlaminar fracture toughness and fatigue delamination onset for Tenax-HTA/R6376 carbon/toughened epoxy composites. The Mode II interlaminar fracture toughness and fatigue delamination onset were characterized using the end-notched flexure (ENF) test while the Mode III interlaminar fracture toughness and fatigue delamination onset were characterized by using the edge crack torsion (ECT) test. Monotonic tests show that the Mode III fracture toughness is higher than the Mode II fracture toughness. Both Mode II and III cyclic loading greatly increases the tendency for a delamination to grow relative to a single monotonically increasing load. Under fatigue loading, the Mode III specimen also has a longer life than the Mode II specimen.

An efficient interior-point algorithm with new non-monotone line search filter method for nonlinear constrained programming

NASA Astrophysics Data System (ADS)

Wang, Liwei; Liu, Xinggao; Zhang, Zeyin

2017-02-01

An efficient primal-dual interior-point algorithm using a new non-monotone line search filter method is presented for nonlinear constrained programming, which is widely applied in engineering optimization. The new non-monotone line search technique is introduced to lead to relaxed step acceptance conditions and improved convergence performance. It can also avoid the choice of the upper bound on the memory, which brings obvious disadvantages to traditional techniques. Under mild assumptions, the global convergence of the new non-monotone line search filter method is analysed, and fast local convergence is ensured by second order corrections. The proposed algorithm is applied to the classical alkylation process optimization problem and the results illustrate its effectiveness. Some comprehensive comparisons to existing methods are also presented.

Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at √s NN = 62.4 and 200 GeV

DOE PAGES

Adare, A.

2015-09-23

We have studied the dependence of azimuthal anisotropy v 2 for inclusive and identified charged hadrons in Au+Au and Cu+Cu collisions on collision energy, species, and centrality. The values of v 2 as a function of transverse momentum pT and centrality in Au+Au collisions at √s NN=200 and 62.4 GeV are the same within uncertainties. However, in Cu+Cu collisions we observe a decrease in v 2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au+Au and Cu+Cu collisions we find that v 2 dependsmore » both on eccentricity and the number of participants, N part. We observe that v 2 divided by eccentricity (ε) monotonically increases with N part and scales as N 1/3 part. Thus, the Cu+Cu data at 62.4 GeV falls below the other scaled v 2 data. For identified hadrons, v 2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy KE T=m T–m between 0.1T/n q<1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu+Cu data at 62.4 GeV, of v 2/(n q∙ε∙N 1/3 part) vs KE T/n q for all measured particles.« less

Does the dose-solubility ratio affect the mean dissolution time of drugs?

PubMed

Lánský, P; Weiss, M

1999-09-01

To present a new model for describing drug dissolution. On the basis of the new model to characterize the dissolution profile by the distribution function of the random dissolution time of a drug molecule, which generalizes the classical first order model. Instead of assuming a constant fractional dissolution rate, as in the classical model, it is considered that the fractional dissolution rate is a decreasing function of the dissolved amount controlled by the dose-solubility ratio. The differential equation derived from this assumption is solved and the distribution measures (half-dissolution time, mean dissolution time, relative dispersion of the dissolution time, dissolution time density, and fractional dissolution rate) are calculated. Finally, instead of monotonically decreasing the fractional dissolution rate, a generalization resulting in zero dissolution rate at time origin is introduced. The behavior of the model is divided into two regions defined by q, the ratio of the dose to the solubility level: q < 1 (complete dissolution of the dose, dissolution time) and q > 1 (saturation of the solution, saturation time). The singular case q = 1 is also treated and in this situation the mean as well as the relative dispersion of the dissolution time increase to infinity. The model was successfully fitted to data (1). This empirical model is descriptive without detailed physical reasoning behind its derivation. According to the model, the mean dissolution time is affected by the dose-solubility ratio. Although this prediction appears to be in accordance with preliminary application, further validation based on more suitable experimental data is required.

Local unitary invariants for N-qubit pure states

NASA Astrophysics Data System (ADS)

Sharma, S. Shelly; Sharma, N. K.

2010-11-01

The concept of negativity font, a basic unit of multipartite entanglement, is introduced. Transformation properties of determinants of negativity fonts under local unitary (LU) transformations are exploited to obtain relevant N-qubit polynomial invariants and construct entanglement monotones from first principles. It is shown that entanglement monotones that detect the entanglement of specific parts of the composite system may be constructed to distinguish between states with distinct types of entanglement. The structural difference between entanglement monotones for an odd and even number of qubits is brought out.

Behavior of the Position-Spread Tensor in Diatomic Systems.

PubMed

Brea, Oriana; El Khatib, Muammar; Angeli, Celestino; Bendazzoli, Gian Luigi; Evangelisti, Stefano; Leininger, Thierry

2013-12-10

The behavior of the Position-Spread Tensor (Λ) in a series of light diatomic molecules (either neutral or negative ions) is investigated at a Full Configuration Interaction level. This tensor, which is the second moment cumulant of the total position operator, is invariant with respect to molecular translations, while its trace is also rotationally invariant. Moreover, the tensor is additive in the case of noninteracting subsystems and can be seen as an intrinsic property of a molecule. In the present work, it is shown that the longitudinal component of the tensor, Λ∥, which is small for internuclear distances close to the equilibrium, tends to grow if the bond is stretched. A maximum is reached in the region of the bond breaking, then Λ∥ decreases and converges toward the isolated-atom value. The degenerate transversal components, Λ⊥, on the other hand, usually have a monotonic growth toward the atomic value. The Position Spread is extremely sensitive to reorganization of the molecular wave function, and it becomes larger in the case of an increase of the electron mobility, as illustrated by the neutral-ionic avoided crossing in LiF. For these reasons, the Position Spread can be an extremely useful property that characterizes the nature of the wave function in a molecular system.

Coupled Protein Diffusion and Folding in the Cell

PubMed Central

Guo, Minghao; Gelman, Hannah; Gruebele, Martin

2014-01-01

When a protein unfolds in the cell, its diffusion coefficient is affected by its increased hydrodynamic radius and by interactions of exposed hydrophobic residues with the cytoplasmic matrix, including chaperones. We characterize protein diffusion by photobleaching whole cells at a single point, and imaging the concentration change of fluorescent-labeled protein throughout the cell as a function of time. As a folded reference protein we use green fluorescent protein. The resulting region-dependent anomalous diffusion is well characterized by 2-D or 3-D diffusion equations coupled to a clustering algorithm that accounts for position-dependent diffusion. Then we study diffusion of a destabilized mutant of the enzyme phosphoglycerate kinase (PGK) and of its stable control inside the cell. Unlike the green fluorescent protein control's diffusion coefficient, PGK's diffusion coefficient is a non-monotonic function of temperature, signaling ‘sticking’ of the protein in the cytosol as it begins to unfold. The temperature-dependent increase and subsequent decrease of the PGK diffusion coefficient in the cytosol is greater than a simple size-scaling model suggests. Chaperone binding of the unfolding protein inside the cell is one plausible candidate for even slower diffusion of PGK, and we test the plausibility of this hypothesis experimentally, although we do not rule out other candidates. PMID:25436502

Coupled protein diffusion and folding in the cell.

PubMed

Guo, Minghao; Gelman, Hannah; Gruebele, Martin

2014-01-01

When a protein unfolds in the cell, its diffusion coefficient is affected by its increased hydrodynamic radius and by interactions of exposed hydrophobic residues with the cytoplasmic matrix, including chaperones. We characterize protein diffusion by photobleaching whole cells at a single point, and imaging the concentration change of fluorescent-labeled protein throughout the cell as a function of time. As a folded reference protein we use green fluorescent protein. The resulting region-dependent anomalous diffusion is well characterized by 2-D or 3-D diffusion equations coupled to a clustering algorithm that accounts for position-dependent diffusion. Then we study diffusion of a destabilized mutant of the enzyme phosphoglycerate kinase (PGK) and of its stable control inside the cell. Unlike the green fluorescent protein control's diffusion coefficient, PGK's diffusion coefficient is a non-monotonic function of temperature, signaling 'sticking' of the protein in the cytosol as it begins to unfold. The temperature-dependent increase and subsequent decrease of the PGK diffusion coefficient in the cytosol is greater than a simple size-scaling model suggests. Chaperone binding of the unfolding protein inside the cell is one plausible candidate for even slower diffusion of PGK, and we test the plausibility of this hypothesis experimentally, although we do not rule out other candidates.

Mitochondrial respiration inhibition after exposure to UWB pulses as a possible mechanism of antitumor action

NASA Astrophysics Data System (ADS)

Zharkova, L.; Romanchenko, I.; Bolshakov, M.; Rostov, V.

2017-05-01

The respiration of isolated mice liver mitochondria after exposure to nanosecond UWB pulses (0.15 - 36 kV/cm, 0.6 - 1.0 GHz centre frequency, 3 - 20 ns pulse duration) has been investigated. The respiratory control (RC, the ratio of oxygen consumption) was estimated. The possibility of mitochondrial membrane electroporation was detected as the decrease in the electrical resistance, according to the β-dispersion of the electric current. The monotonous decrease of RC after 1000 UWB pulses from 0.15 kV/cm was observed, the ohmic resistance of mitochondria suspension was reduced. The obtained data indicate the inhibitory effect of UWB pulses on a state of irradiated mitochondria and its membrane.

Transparent conductive p-type lithium-doped nickel oxide thin films deposited by pulsed plasma deposition

NASA Astrophysics Data System (ADS)

Huang, Yanwei; Zhang, Qun; Xi, Junhua; Ji, Zhenguo

2012-07-01

Transparent p-type Li0.25Ni0.75O conductive thin films were prepared on conventional glass substrates by pulsed plasma deposition. The effects of substrate temperature and oxygen pressure on structural, electrical and optical properties of the films were investigated. The electrical resistivity decreases initially and increases subsequently as the substrate temperature increases. As the oxygen pressure increases, the electrical resistivity decreases monotonically. The possible physical mechanism was discussed. And a hetero p-n junction of p-Li0.25Ni0.75O/n-SnO2:W was fabricated by depositing n-SnO2:W on top of the p-Li0.25Ni0.75O, which exhibits typical rectifying current-voltage characteristics.

Effect of group electronegativity on electron transfer in bis(hydrazine) radical cations.

PubMed

Qin, Haimei; Zhong, Xinxin; Si, Yubing; Zhang, Weiwei; Zhao, Yi

2011-04-14

The radical cation of 4,10-ditert-butyl-5,9-diisopropyl-4,5,9,10-tetraazatetracyclo[6.2.2.2]-tetradecane (sBI4T(+)), as well as its substituted bis(hydrazine) radical cations, is chosen for the investigation of the electronegativity dependence of its intramolecular electron transfer. To do so, two parameters, reorganization energy and electronic coupling, are calculated with several ab initio approaches. It is found that the electronic couplings decrease with the increase of the group electronegativity while the reorganization energies do not show an explicit dependency. Furthermore, Marcus formula is employed to reveal those effect on the electron transfer rates. The predicted rates of electron transfer generally decrease with increasing group electronegativity, although not monotonically.

Tuning exciton energy and fine-structure splitting in single InAs quantum dots by applying uniaxial stress

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

Su, Dan; Dou, Xiuming; Wu, Xuefei

2016-04-15

Exciton and biexciton emission energies as well as excitonic fine-structure splitting (FSS) in single InAs/GaAs quantum dots (QDs) have been continuously tuned in situ in an optical cryostat using a developed uniaxial stress device. With increasing tensile stress, the red shift of excitonic emission is up to 5 nm; FSS decreases firstly and then increases monotonically, reaching a minimum value of approximately 10 μeV; biexciton binding energy decreases from 460 to 106 μeV. This technique provides a simple and convenient means to tune QD structural symmetry, exciton energy and biexciton binding energy and can be used for generating entangled andmore » indistinguishable photons.« less

Airborne detection of oceanic turbidity cell structure using depth-resolved laser-induced water Raman backscatter

NASA Technical Reports Server (NTRS)

Hoge, F. E.; Swift, R. N.

1983-01-01

Airborne laser-induced, depth-resolved water Raman backscatter is useful in the detection and mapping of water optical transmission variations. This test, together with other field experiments, has identified the need for additional field experiments to resolve the degree of the contribution to the depth-resolved, Raman-backscattered signal waveform that is due to (1) sea surface height or elevation probability density; (2) off-nadir laser beam angle relative to the mean sea surface; and (3) the Gelbstoff fluorescence background, and the analytical techniques required to remove it. When converted to along-track profiles, the waveforms obtained reveal cells of a decreased Raman backscatter superimposed on an overall trend of monotonically decreasing water column optical transmission.

THE EXCEPTIONAL SETS ON THE RUN-LENGTH FUNCTION OF β-EXPANSIONS

NASA Astrophysics Data System (ADS)

Zheng, Lixuan; Wu, Min; Li, Bing

Let β > 1 and the run-length function rn(x,β) be the maximal length of consecutive zeros amongst the first n digits in the β-expansion of x ∈ [0, 1]. The exceptional set Emaxφ = x ∈ [0, 1] :liminf n→∞rn(x,β) φ(n) = 0,limsupn→∞rn(x,β) φ(n) = +∞ is investigated, where φ : ℕ → ℝ+ is a monotonically increasing function with limn→∞φ(n) = +∞. We prove that the set Emaxφ is either empty or of full Hausdorff dimension and residual in [0, 1] according to the increasing rate of φ.

Thermalization of Heavy Ions in the Solar Wind

NASA Astrophysics Data System (ADS)

Tracy, Patrick J.; Kasper, Justin C.; Zurbuchen, Thomas H.; Raines, Jim M.; Shearer, Paul; Gilbert, Jason

2015-10-01

Observations of velocity distribution functions from the Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer heavy ion composition instrument are used to calculate ratios of kinetic temperature and Coulomb collisional interactions of an unprecedented 50 ion species in the solar wind. These ions cover a mass per charge range of 1-5.5 amu/e and were collected in the time range of 1998-2011. We report the first calculation of the Coulomb thermalization rate between each of the heavy ion (A > 4 amu) species present in the solar wind along with protons (H+) and alpha particles (He2+). From these rates, we find that protons are the dominant source of Coulomb collisional thermalization for heavy ions in the solar wind and use this fact to calculate a collisional age for those heavy ion populations. The heavy ion thermal properties are well organized by this collisional age, but we find that the temperature of all heavy ions does not simply approach that of protons as Coulomb collisions become more important. We show that He2+ and C6+ follow a monotonic decay toward equal temperatures with protons with increasing collisional age, but O6+ shows a noted deviation from this monotonic decay. Furthermore, we show that the deviation from monotonic decay for O6+ occurs in solar wind of all origins, as determined by its Fe/O ratio. The observed differences in heavy ion temperature behavior point toward a local heating mechanism that favors ions depending on their charge and mass.

Protein assembly and heat stability in developing thylakoid membranes during greening

PubMed Central

Kóta, Zoltán; Horváth, László I.; Droppa, Magdolna; Horváth, Gábor; Farkas, Tibor; Páli, Tibor

2002-01-01

The development of the thylakoid membrane was studied during illumination of dark-grown barley seedlings by using biochemical methods, and Fourier transform infrared and spin label electron paramagnetic resonance spectroscopic techniques. Correlated, gross changes in the secondary structure of membrane proteins, conformation, composition, and dynamics of lipid acyl chains, SDS/PAGE pattern, and thermally induced structural alterations show that greening is accompanied with the reorganization of membrane protein assemblies and the protein–lipid interface. Changes in overall membrane fluidity and noncovalent protein–lipid interactions are not monotonic, despite the monotonic accumulation of chlorophyll, LHCII [light-harvesting chlorophyll a/b-binding (polypeptides) associated with photosystem II] apoproteins, and 18:3 fatty acids that follow a similar time course with highest rates between 12–24 h of greening. The 18:3 fatty acid content increases 2.8-fold during greening. This appears to both compensate for lipid immobilization by membrane proteins and facilitate packing of larger protein assemblies. The increase in the amount of protein-solvating immobile lipids, which reaches a maximum at 12 h, is caused by 40% decrease in the membranous mean diameter of protein assemblies at constant protein/lipid mass ratio. Alterations in the SDS/PAGE pattern are most significant between 6–24 h. The size of membrane protein assemblies increases ≈4.5-fold over the 12–48-h period, likely caused by the 2-fold gain in LHCII apoproteins. The thermal stability of thylakoid membrane proteins increases monotonically, as detected by an increasing temperature of partial protein unfolding during greening. Our data suggest that a structural coupling between major protein and lipid components develops during greening. This protein–lipid interaction is required for the development and protection of thylakoid membrane protein assemblies. PMID:12213965

Non-monotonic behavior of electron temperature in argon inductively coupled plasma and its analysis via novel electron mean energy equation

NASA Astrophysics Data System (ADS)

Zhao, Shu-Xia

2018-03-01

In this work, the behavior of electron temperature against the power in argon inductively coupled plasma is investigated by a fluid model. The model properly reproduces the non-monotonic variation of temperature with power observed in experiments. By means of a novel electron mean energy equation proposed for the first time in this article, this electron temperature behavior is interpreted. In the overall considered power range, the skin effect of radio frequency electric field results in localized deposited power density, responsible for an increase of electron temperature with power by means of one parameter defined as power density divided by electron density. At low powers, the rate fraction of multistep and Penning ionizations of metastables that consume electron energy two times significantly increases with power, which dominates over the skin effect and consequently leads to the decrease of temperature with power. In the middle power regime, a transition region of temperature is given by the competition between the ionizing effect of metastables and the skin effect of electric field. The power location where the temperature alters its trend moves to the low power end as increasing the pressure due to the lack of metastables. The non-monotonic curve of temperature is asymmetric at the short chamber due to the weak role of skin effect in increasing the temperature and tends symmetric when axially prolonging the chamber. Still, the validity of the fluid model in this prediction is estimated and the role of neutral gas heating is guessed. This finding is helpful for people understanding the different trends of temperature with power in the literature.

Convergence of damped inertial dynamics governed by regularized maximally monotone operators

NASA Astrophysics Data System (ADS)

Attouch, Hedy; Cabot, Alexandre

2018-06-01

In a Hilbert space setting, we study the asymptotic behavior, as time t goes to infinity, of the trajectories of a second-order differential equation governed by the Yosida regularization of a maximally monotone operator with time-varying positive index λ (t). The dissipative and convergence properties are attached to the presence of a viscous damping term with positive coefficient γ (t). A suitable tuning of the parameters γ (t) and λ (t) makes it possible to prove the weak convergence of the trajectories towards zeros of the operator. When the operator is the subdifferential of a closed convex proper function, we estimate the rate of convergence of the values. These results are in line with the recent articles by Attouch-Cabot [3], and Attouch-Peypouquet [8]. In this last paper, the authors considered the case γ (t) = α/t, which is naturally linked to Nesterov's accelerated method. We unify, and often improve the results already present in the literature.

Temperature dependent exchange bias training effect in single-crystalline BiFeO{sub 3}/Co bilayers

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

He, M. C.; You, B.; Tu, H. Q.

2015-05-07

Single-crystalline BiFeO{sub 3} (BFO)/Co bilayers were prepared by combined pulsed laser deposition and magnetron sputtering on (001) SrTiO{sub 3} substrates. Exchange bias (EB) and accompanying training effect have been studied as a function of temperature (T) between 5 K and 300 K. A non-monotonic exchange field variation with sharp increase below 100 K has been observed. In the meanwhile, strong training effect was recorded when T < 100 K and it weakens monotonically with increasing T up to 300 K. These temperature dependent EB and training effect may be caused by the uncompensated spins in both the interfacial spin-glass (SG) phase at low temperature and the antiferromagneticmore » BFO layer at higher temperature. The low temperature EB training results can be well fitted by a modified Binek's model considering asymmetric changes of the pinning SG spins at the descending and the ascending branches.« less

Theoretical Current-Voltage Curve in Low-Pressure Cesium Diode for Electron-Rich Emission

NASA Technical Reports Server (NTRS)

Coldstein, C. M.

1964-01-01

Although considerable interest has been shown in the space-charge analysis of low-pressure (collisionless case) thermionic diodes, there is a conspicuous lack in the presentation of results in a way that allows direct comparison with experiment. The current-voltage curve of this report was, therefore, computed for a typical case within the realm of experimental interest. The model employed in this computation is shown in Fig. 1 and is defined by the limiting potential distributions [curves (a) and (b)]. Curve (a) represents the potential V as a monotonic function of position with a slope of zero at the anode; curve (b) is similarly monotonic with a slope of zero at the cathode. It is assumed that by a continuous variation of the anode voltage, the potential distributions vary continuously from one limiting form to the other. Although solutions for infinitely spaced electrodes show that spatically oscillatory potential distributions may exist, they have been neglected in this computation.

Computation of the anharmonic orbits in two piecewise monotonic maps with a single discontinuity

NASA Astrophysics Data System (ADS)

Li, Yurong; Du, Zhengdong

2017-02-01

In this paper, the bifurcation values for two typical piecewise monotonic maps with a single discontinuity are computed. The variation of the parameter of those maps leads to a sequence of border-collision and period-doubling bifurcations, generating a sequence of anharmonic orbits on the boundary of chaos. The border-collision and period-doubling bifurcation values are computed by the word-lifting technique and the Maple fsolve function or the Newton-Raphson method, respectively. The scaling factors which measure the convergent rates of the bifurcation values and the width of the stable periodic windows, respectively, are investigated. We found that these scaling factors depend on the parameters of the maps, implying that they are not universal. Moreover, if one side of the maps is linear, our numerical results suggest that those quantities converge increasingly. In particular, for the linear-quadratic case, they converge to one of the Feigenbaum constants δ _F= 4.66920160\\cdots.

Nonoscillatory behavior in the magnetoresistance of Cu/Ni superlattice (abstract)

NASA Astrophysics Data System (ADS)

Abdul-Razzaq, W.

1994-05-01

It was reported that in many magnetic/nonmagnetic metallic multilayered systems, the interlayer-coupling oscillates between antiferromagnetic and ferromagnetic upon increasing the thickness of the nonmagnetic layer. This was evident by the oscillation of the magnetoresistance (MR) in these materials. Recently however, Harp, Parkin et al.1 found that the MR and coupling strength change monotonically with increasing Cu thickness in Co/Cu multilayers deposited by MBE, contradicting results on similar samples made by sputtering in which the MR was oscillatory. In this study, we show that in the Cu/Ni superlattice made by sputtering, the MR varies monotonically with increasing Cu thickness. This nonoscillatory behavior was observed at room temperature and at 77 K and, regardless of the direction of the magnetic field in relation to the direction of the current. The resistivity at zero magnetic field as a function of temperature also changes systematically with reducing the Cu layer thickness. The nature of the magnetic state in Cu/Ni superlattice is discussed in light of the transport property measurements.

Does Your Optical Particle Counter Measure What You Think it Does? Calibration and Refractive Index Correction Methods.

NASA Astrophysics Data System (ADS)

Rosenberg, Phil; Dean, Angela; Williams, Paul; Dorsey, James; Minikin, Andreas; Pickering, Martyn; Petzold, Andreas

2013-04-01

Optical Particle Counters (OPCs) are the de-facto standard for in-situ measurements of airborne aerosol size distributions and small cloud particles over a wide size range. This is particularly the case on airborne platforms where fast response is important. OPCs measure scattered light from individual particles and generally bin particles according to the measured peak amount of light scattered (the OPC's response). Most manufacturers provide a table along with their instrument which indicates the particle diameters which represent the edges of each bin. It is important to correct the particle size reported by OPCs for the refractive index of the particles being measured, which is often not the same as for those used during calibration. However, the OPC's response is not a monotonic function of particle diameter and obvious problems occur when refractive index corrections are attempted, but multiple diameters correspond to the same OPC response. Here we recommend that OPCs are calibrated in terms of particle scattering cross section as this is a monotonic (usually linear) function of an OPC's response. We present a method for converting a bin's boundaries in terms of scattering cross section into a bin centre and bin width in terms of diameter for any aerosol species for which the scattering properties are known. The relationship between diameter and scattering cross section can be arbitrarily complex and does not need to be monotonic; it can be based on Mie-Lorenz theory or any other scattering theory. Software has been provided on the Sourceforge open source repository for scientific users to implement such methods in their own measurement and calibration routines. As a case study data is presented showing data from Passive Cavity Aerosol Spectrometer Probe (PCASP) and a Cloud Droplet Probe (CDP) calibrated using polystyrene latex spheres and glass beads before being deployed as part of the Fennec project to measure airborne dust in the inaccessible regions of the Sahara.

Dealing with non-unique and non-monotonic response in particle sizing instruments

NASA Astrophysics Data System (ADS)

Rosenberg, Phil

2017-04-01

A number of instruments used as de-facto standards for measuring particle size distributions are actually incapable of uniquely determining the size of an individual particle. This is due to non-unique or non-monotonic response functions. Optical particle counters have non monotonic response due to oscillations in the Mie response curves, especially for large aerosol and small cloud droplets. Scanning mobility particle sizers respond identically to two particles where the ratio of particle size to particle charge is approximately the same. Images of two differently sized cloud or precipitation particles taken by an optical array probe can have similar dimensions or shadowed area depending upon where they are in the imaging plane. A number of methods exist to deal with these issues, including assuming that positive and negative errors cancel, smoothing response curves, integrating regions in measurement space before conversion to size space and matrix inversion. Matrix inversion (also called kernel inversion) has the advantage that it determines the size distribution which best matches the observations, given specific information about the instrument (a matrix which specifies the probability that a particle of a given size will be measured in a given instrument size bin). In this way it maximises use of the information in the measurements. However this technique can be confused by poor counting statistics which can cause erroneous results and negative concentrations. Also an effective method for propagating uncertainties is yet to be published or routinely implemented. Her we present a new alternative which overcomes these issues. We use Bayesian methods to determine the probability that a given size distribution is correct given a set of instrument data and then we use Markov Chain Monte Carlo methods to sample this many dimensional probability distribution function to determine the expectation and (co)variances - hence providing a best guess and an uncertainty for the size distribution which includes contributions from the non-unique response curve, counting statistics and can propagate calibration uncertainties.

Estimating monotonic rates from biological data using local linear regression.

PubMed

Olito, Colin; White, Craig R; Marshall, Dustin J; Barneche, Diego R

2017-03-01

Accessing many fundamental questions in biology begins with empirical estimation of simple monotonic rates of underlying biological processes. Across a variety of disciplines, ranging from physiology to biogeochemistry, these rates are routinely estimated from non-linear and noisy time series data using linear regression and ad hoc manual truncation of non-linearities. Here, we introduce the R package LoLinR, a flexible toolkit to implement local linear regression techniques to objectively and reproducibly estimate monotonic biological rates from non-linear time series data, and demonstrate possible applications using metabolic rate data. LoLinR provides methods to easily and reliably estimate monotonic rates from time series data in a way that is statistically robust, facilitates reproducible research and is applicable to a wide variety of research disciplines in the biological sciences. © 2017. Published by The Company of Biologists Ltd.

Anomalous photoconductive behavior of a single InAs nanowire photodetector

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

Li, Junshuai; Yan, Xin; Sun, Fukuan

2015-12-28

We report on a bare InAs nanowire photodetector which exhibits an anomalous photoconductive behavior. Under low-power illumination, the current is smaller than the dark current, and monotonously decreases as the excitation power increases. When the excitation power is high enough, the current starts to increase normally. The phenomenon is attributed to different electron mobilities in the “core” and “shell” of a relatively thick nanowire originating from the surface effect, which result in a quickly dropped “core current” and slowly increased “shell current” under illumination.

Luminescent Photoelectrochemical Cells. 7. Photoluminescent and Electroluminescent Properties of Cadmium Sulfo-Selenide Electrodes.

DTIC Science & Technology

1981-10-06

STRECKERT, J TONG. M K CARPENTER N00014-76"C-0633 UNCLASSIFIED TR-9 NL* EIIIIEIIIIEE IIIIIIIIIIIIIIfllfllf IIIIIIIIIII2 LEVEV, OFFICE OF NAVAL RESEARCH i...REPORT DATE Office of Naval Research /Chemistry Program October 6, 1981 Arlington, Virginia 22217 13. NUMBER OF PAGES 37 14. MONITORING AGENCY NAME 6...0.11, 0.00) emit when excited with ultraband gap excitation. The 295 K band gaps monotonically decrease with X from ’U2.4 eV for CdS to \\,1.7 eV for

Development of advanced high strength tantalum base alloys. Part 1: Screening investigation

NASA Technical Reports Server (NTRS)

Buckman, R. W., Jr.

1971-01-01

Five experimental tantalum alloy compositions containing 13-18% W+Re+Hf solid solution solute additions with dispersed phase strengthening achieved by carbon or nitrogen additions were prepared as 1.4 inch diameter ingot processed to 3/8 inch diameter rod and evaluated. Elevated temperature tensile and creep strength increased monotonically with increasing solute content. Room temperature elongation decreased for 20% to less than 2% as the solute content was increased above 16%. Phase identification indicated that the precipitating phase in the carbide containing alloys was Ta2C.

Criterion for estimation of stress-deformed state of SD-materials

NASA Astrophysics Data System (ADS)

Orekhov, Andrey V.

2018-05-01

A criterion is proposed that determines the moment when the growth pattern of the monotonic numerical sequence varies from the linear to the parabolic one. The criterion is based on the comparison of squares of errors for the linear and the incomplete quadratic approximation. The approximating functions are constructed locally, only at those points that are located near a possible change in nature of the increase in the sequence.

Numerical simulation of a flow past a triangular sail-type blade of a wind generator using the ANSYS FLUENT software package

NASA Astrophysics Data System (ADS)

Kusaiynov, K.; Tanasheva, N. K.; Min'kov, L. L.; Nusupbekov, B. R.; Stepanova, Yu. O.; Rozhkova, A. V.

2016-02-01

An air flow past a single triangular sail-type blade of a wind turbine is analyzed by numerical simulation for low velocities of the incoming flow. The results of numerical simulation indicate a monotonic increase in the drag force and the lift force as functions of the incoming flow; empirical dependences of these quantities are obtained.

Beyond stereotypes of adolescent risk taking: Placing the adolescent brain in developmental context.

PubMed

Romer, Daniel; Reyna, Valerie F; Satterthwaite, Theodore D

2017-10-01

Recent neuroscience models of adolescent brain development attribute the morbidity and mortality of this period to structural and functional imbalances between more fully developed limbic regions that subserve reward and emotion as opposed to those that enable cognitive control. We challenge this interpretation of adolescent development by distinguishing risk-taking that peaks during adolescence (sensation seeking and impulsive action) from risk taking that declines monotonically from childhood to adulthood (impulsive choice and other decisions under known risk). Sensation seeking is primarily motivated by exploration of the environment under ambiguous risk contexts, while impulsive action, which is likely to be maladaptive, is more characteristic of a subset of youth with weak control over limbic motivation. Risk taking that declines monotonically from childhood to adulthood occurs primarily under conditions of known risks and reflects increases in executive function as well as aversion to risk based on increases in gist-based reasoning. We propose an alternative Life-span Wisdom Model that highlights the importance of experience gained through exploration during adolescence. We propose, therefore, that brain models that recognize the adaptive roles that cognition and experience play during adolescence provide a more complete and helpful picture of this period of development. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

River rating complexity

USGS Publications Warehouse

Holmes, Robert R.

2016-01-01

Accuracy of streamflow data depends on the veracity of the rating model used to derive a continuous time series of discharge from the surrogate variables that can readily be collected autonomously at a streamgage. Ratings are typically represented as a simple monotonic increasing function (simple rating), meaning the discharge is a function of stage alone, however this is never truly the case unless the flow is completely uniform at all stages and in transitions from one stage to the next. For example, at some streamflow-monitoring sites the discharge on the rising limb of the hydrograph is discernably larger than the discharge at the same stage on the falling limb of the hydrograph. This is the so-called “loop rating curve” (loop rating). In many cases, these loops are quite small and variation between rising- and falling-limb discharge measurements made at the same stage are well within the accuracy of the measurements. However, certain hydraulic conditions can produce a loop that is large enough to preclude use of a monotonic rating. A detailed data campaign for the Mississippi River at St. Louis, Missouri during a multi-peaked flood over a 56-day period in 2015 demonstrates the rating complexity at this location. The shifting-control method used to deal with complexity at this site matched all measurements within 8%.

Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

2015-07-01

We present results of analyses of two-pion interferometry in Au +Au collisions at √{sNN}=7.7 , 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the BNL Relativistic Heavy Ion Collider Beam Energy Scan program. The extracted correlation lengths (Hanbury-Brown-Twiss radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.

Quantum parameter estimation in the Unruh–DeWitt detector model

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

Hao, Xiang, E-mail: xhao@phas.ubc.ca; Pacific Institute of Theoretical Physics, Department of Physics and Astronomy, University of British Columbia, 6224 Agriculture Rd., Vancouver B.C., Canada V6T 1Z1; Wu, Yinzhong

2016-09-15

Relativistic effects on the precision of quantum metrology for particle detectors, such as two-level atoms are studied. The quantum Fisher information is used to estimate the phase sensitivity of atoms in non-inertial motions or in gravitational fields. The Unruh–DeWitt model is applicable to the investigation of the dynamics of a uniformly accelerated atom weakly coupled to a massless scalar vacuum field. When a measuring device is in the same relativistic motion as the atom, the dynamical behavior of quantum Fisher information as a function of Rindler proper time is obtained. It is found out that monotonic decrease in phase sensitivitymore » is characteristic of dynamics of relativistic quantum estimation. The origin of the decay of quantum Fisher information is the thermal bath that the accelerated detector finds itself in due to the Unruh effect. To improve relativistic quantum metrology, we reasonably take into account two reflecting plane boundaries perpendicular to each other. The presence of the reflecting boundary can shield the detector from the thermal bath in some sense.« less

One-dimensional pion, kaon, and proton femtoscopy in Pb-Pb collisions at s NN = 2.76 TeV

DOE PAGES

Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

2015-11-19

Tmore » he size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of π ± π ±, K ± K ±, K$$0\\atop{S}$$K$$0\\atop{S}$$, pp , and $$\\overline{p}$$ $$\\overline{p}$$ correlations from Pb-Pb collisions at s NN = 2.76 eV by the ALICE experiment at the LHC. One-dimensional radii of the system are extracted from correlation functions in terms of the invariant momentum difference of the pair. he comparison of the measured radii with the predictions from a hydrokinetic model is discussed. he pion and kaon source radii display a monotonic decrease with increasing average pair transverse mass m which is consistent with hydrodynamic model predictions for central collisions. Lastly, the kaon and proton source sizes can be reasonably described by approximate m scaling.« less

Neural basis of the undermining effect of monetary reward on intrinsic motivation

PubMed Central

Murayama, Kou; Matsumoto, Madoka; Izuma, Keise; Matsumoto, Kenji

2010-01-01

Contrary to the widespread belief that people are positively motivated by reward incentives, some studies have shown that performance-based extrinsic reward can actually undermine a person's intrinsic motivation to engage in a task. This “undermining effect” has timely practical implications, given the burgeoning of performance-based incentive systems in contemporary society. It also presents a theoretical challenge for economic and reinforcement learning theories, which tend to assume that monetary incentives monotonically increase motivation. Despite the practical and theoretical importance of this provocative phenomenon, however, little is known about its neural basis. Herein we induced the behavioral undermining effect using a newly developed task, and we tracked its neural correlates using functional MRI. Our results show that performance-based monetary reward indeed undermines intrinsic motivation, as assessed by the number of voluntary engagements in the task. We found that activity in the anterior striatum and the prefrontal areas decreased along with this behavioral undermining effect. These findings suggest that the corticobasal ganglia valuation system underlies the undermining effect through the integration of extrinsic reward value and intrinsic task value. PMID:21078974

Adaptive dynamic programming for discrete-time linear quadratic regulation based on multirate generalised policy iteration

NASA Astrophysics Data System (ADS)

Chun, Tae Yoon; Lee, Jae Young; Park, Jin Bae; Choi, Yoon Ho

2018-06-01

In this paper, we propose two multirate generalised policy iteration (GPI) algorithms applied to discrete-time linear quadratic regulation problems. The proposed algorithms are extensions of the existing GPI algorithm that consists of the approximate policy evaluation and policy improvement steps. The two proposed schemes, named heuristic dynamic programming (HDP) and dual HDP (DHP), based on multirate GPI, use multi-step estimation (M-step Bellman equation) at the approximate policy evaluation step for estimating the value function and its gradient called costate, respectively. Then, we show that these two methods with the same update horizon can be considered equivalent in the iteration domain. Furthermore, monotonically increasing and decreasing convergences, so called value iteration (VI)-mode and policy iteration (PI)-mode convergences, are proved to hold for the proposed multirate GPIs. Further, general convergence properties in terms of eigenvalues are also studied. The data-driven online implementation methods for the proposed HDP and DHP are demonstrated and finally, we present the results of numerical simulations performed to verify the effectiveness of the proposed methods.

Computer simulation of a cellular automata model for the immune response in a retrovirus system

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

Pandey, R.B.

1989-02-01

Immune response in a retrovirus system is modeled by a network of three binary cell elements to take into account some of the main functional features of T4 cells, T8 cells, and viruses. Two different intercell interactions are introduced, one of which leads to three fixed points while the other yields bistable fixed points oscillating between a healthy state and a sick state in a mean field treatment. Evolution of these cells is studied for quenched and annealed random interactions on a simple cubic lattice with a nearest neighbor interaction using inhomogenous cellular automata. Populations of T4 cells and viralmore » cells oscillate together with damping (with constant amplitude) for annealed (quenched) interaction on increasing the value of mixing probability B from zero to a characteristic value B/sub ca/ (B/sub cq/). For higher B, the average number of T4 cells increases while that of the viral infected cells decreases monotonically on increasing B, suggesting a phase transition at B/sub ca/ (B/sub cq/).« less

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

Zhang, Jingchao, E-mail: zhang@unl.edu, E-mail: yyue@whu.edu.cn; Hong, Yang; Yue, Yanan, E-mail: zhang@unl.edu, E-mail: yyue@whu.edu.cn

As the dimensions of nanocircuits and nanoelectronics shrink, thermal energies are being generated in more confined spaces, making it extremely important and urgent to explore for efficient heat dissipation pathways. In this work, the phonon energy transport across graphene and hexagonal boron-nitride (h-BN) interface is studied using classic molecular dynamics simulations. Effects of temperature, interatomic bond strength, heat flux direction, and functionalization on interfacial thermal transport are investigated. It is found out that by hydrogenating graphene in the hybrid structure, the interfacial thermal resistance (R) between graphene and h-BN can be reduced by 76.3%, indicating an effective approach to manipulatemore » the interfacial thermal transport. Improved in-plane/out-of-plane phonon couplings and broadened phonon channels are observed in the hydrogenated graphene system by analyzing its phonon power spectra. The reported R results monotonically decrease with temperature and interatomic bond strengths. No thermal rectification phenomenon is observed in this interfacial thermal transport. Results reported in this work give the fundamental knowledge on graphene and h-BN thermal transport and provide rational guidelines for next generation thermal interface material designs.« less

Effects of convection electric field on the distribution of ring current type protons

NASA Technical Reports Server (NTRS)

Grebowsky, J. M.; Chen, A. J.

1975-01-01

The topology of the boundaries of penetration (or, inversely, the boundaries of the forbidden regions) of 90-deg pitch-angle equatorial protons with energies less than 100 keV are explored for an equatorial convection E-field which is directed in general from dawn to dusk. Due to the dependence of drift path on energy (or magnetic moment), complex structural features are expected in the proton energy spectra detected by satellites since the penetration distance of a proton is not a monotonically increasing or decreasing function of energy. During a storm when the convection E is enhanced, model calculations predict elongations of the forbidden regions analogous to tail extensions of the plasmasphere. Following a reduction in the convection field, spiral-structured forbidden regions can occur. Structural features inherent to large-scale convection field changes may be seen in the nose-like proton spectrograms observed near dusk by instrumentation on Explorer 45. These nose events are modelled by using an electric field model developed originally by Volland (1973). The strength of the field is related to the Kp index through night-time equatorial plasmapause measurements.

Experimental measurement of coil-rod-coil block copolymer tracer diffusion through entangled coil homopolymers

PubMed Central

Wang, Muzhou; Timachova, Ksenia; Olsen, Bradley D.

2014-01-01

The diffusion of coil-rod-coil triblock copolymers in entangled coil homopolymers is experimentally measured and demonstrated to be significantly slower than rod or coil homopolymers of the same molecular weight. A model coil-rod-coil triblock was prepared by expressing rodlike alanine-rich α-helical polypeptides in E. coli and conjugating coillike poly(ethylene oxide) (PEO) to both ends to form coil-rod-coil triblock copolymers. Tracer diffusion through entangled PEO homopolymer melts was measured using forced Rayleigh scattering at various rod lengths, coil molecular weights, and coil homopolymer concentrations. For rod lengths, L, that are close to the entanglementh length, a, the ratio between triblock diffusivity and coil homopolymer diffusivity decreases monotonically and is only a function of L/a, in quantitative agreement with previous simulation results. For large rod lengths, diffusion follows an arm retraction scaling, which is also consistent with previous theoretical predictions. These experimental results support the key predictions of theory and simulation, suggesting that the mismatch in curvature between rod and coil entanglement tubes leads to the observed diffusional slowing. PMID:25484454

One-dimensional pion, kaon, and proton femtoscopy in Pb-Pb collisions at √{sNN}=2.76 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Chunhui, Z.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; D'Erasmo, G.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hilden, T. E.; Hillemanns, H.; Hippolyte, B.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Ionita, C.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jadlovska, S.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Khan, K. H.; Khan, M. M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Kox, S.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kravčáková, A.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kulakov, I.; Kumar, J.; Kumar, L.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Legrand, I.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Luz, P. H. F. N. D.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Masui, H.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira de Godoy, D. A.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S. K.; Pan, J.; Pandey, A. K.; Pant, D.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Peitzmann, T.; Pereira da Costa, H.; Pereira de Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Šándor, L.; Sandoval, A.; Sano, M.; Santagati, G.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Seeder, K. S.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Symons, T. J. M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Takahashi, J.; Tanaka, N.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Wang, Y.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

2015-11-01

The size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of π±π±,K±K±,KS0KS0,p p , and p ¯p ¯ correlations from Pb-Pb collisions at √{sNN}=2.76 TeV by the ALICE experiment at the LHC. One-dimensional radii of the system are extracted from correlation functions in terms of the invariant momentum difference of the pair. The comparison of the measured radii with the predictions from a hydrokinetic model is discussed. The pion and kaon source radii display a monotonic decrease with increasing average pair transverse mass mT which is consistent with hydrodynamic model predictions for central collisions. The kaon and proton source sizes can be reasonably described by approximate mT scaling.

Matrix stiffness modulates infection of endothelial cells by Listeria monocytogenes via expression of cell surface vimentin.

PubMed

Bastounis, Effie E; Yeh, Yi-Ting; Theriot, Julie A

2018-05-02

Extracellular matrix stiffness (ECM) is one of the many mechanical forces acting on mammalian adherent cells and an important determinant of cellular function. While the effect of ECM stiffness on many aspects of cellular behavior has been previously studied, how ECM stiffness might mediate susceptibility of host cells to infection by bacterial pathogens was hitherto unexplored. To address this open question, we manufactured hydrogels of varying physiologically-relevant stiffness and seeded human microvascular endothelial cells (HMEC-1) on them. We then infected HMEC-1 with the bacterial pathogen Listeria monocytogenes (Lm), and found that adhesion of Lm onto host cells increases monotonically with increasing matrix stiffness, an effect that requires the activity of focal adhesion kinase (FAK). We identified cell surface vimentin as a candidate surface receptor mediating stiffness-dependent adhesion of Lm to HMEC-1 and found that bacterial infection of these host cells is decreased when the amount of surface vimentin is reduced. Our results provide the first evidence that ECM stiffness can mediate the susceptibility of mammalian host cells to infection by a bacterial pathogen.