Density dependence of reactor performance with thermal confinement scalings

International Nuclear Information System (INIS)

Stotler, D.P.

1992-03-01

Energy confinement scalings for the thermal component of the plasma published thus far have a different dependence on plasma density and input power than do scalings for the total plasma energy. With such thermal scalings, reactor performance (measured by Q, the ratio of the fusion power to the sum of the ohmic and auxiliary input powers) worsens with increasing density. This dependence is the opposite of that found using scalings based on the total plasma energy, indicating that reactor operation concepts may need to be altered if this density dependence is confirmed in future research

A potential mechanism for allometric trabecular bone scaling in terrestrial mammals.

Science.gov (United States)

Christen, Patrik; Ito, Keita; van Rietbergen, Bert

2015-03-01

Trabecular bone microstructural parameters, including trabecular thickness, spacing, and number, have been reported to scale with animal size with negative allometry, whereas bone volume fraction is animal size-invariant in terrestrial mammals. As for the majority of scaling patterns described in animals, its underlying mechanism is unknown. However, it has also been found that osteocyte density is inversely related to animal size, possibly adapted to metabolic rate, which shows a negative relationship as well. In addition, the signalling reach of osteocytes is limited by the extent of the lacuno-canalicular network, depending on trabecular dimensions and thus also on animal size. Here we propose animal size-dependent variations in osteocyte density and their signalling influence distance as a potential mechanism for negative allometric trabecular bone scaling in terrestrial mammals. Using an established and tested computational model of bone modelling and remodelling, we run simulations with different osteocyte densities and influence distances mimicking six terrestrial mammals covering a large range of body masses. Simulated trabecular structures revealed negative allometric scaling for trabecular thickness, spacing, and number, constant bone volume fraction, and bone turnover rates inversely related to animal size. These results are in agreement with previous observations supporting our proposal of osteocyte density and influence distance variation as a potential mechanism for negative allometric trabecular bone scaling in terrestrial mammals. The inverse relationship between bone turnover rates and animal size further indicates that trabecular bone scaling may be linked to metabolic rather than mechanical adaptations. © 2015 Anatomical Society.

Equivalence between deep energy-dependent and shallow angular momentum dependent potentials

International Nuclear Information System (INIS)

Fiedeldey, H.; Sofianos, S.A.; Papastylianos, A.; Amos, K.A.; Allen, L.J.

1989-01-01

Recently Baye showed that supersymmetry can be applied to determine a shallow l-dependent potential phase equivalent to a deep potential, assumed to be energy-independent and have Panli forbidden states (PFS), for α-α scattering. The PFS are eliminated by this procedure. Such deep potentials are generated as equivalent local potentials (ELP) to the Resonating Group Model (RGM) and are generally energy-dependent. To eliminate this E-dependence as required for the application of Baye's method, l-dependent, but E-independent, deep local potentials were generated by the exact inversion method of Marchenko. Subsequently, the supersymmetric method was used to eliminate the PFS, ensuring that the generalized Levinson theorem is satisfied. As an example, the method was applied to the simple model of two dineutrons scattering in the RGM, where the deep ELP of Horiuchi has a substantial energy-dependence and one PFS only for l=O. 16 refs., 5 figs

[Development of a New Scale for Gauging Smartphone Dependence].

Science.gov (United States)

Toda, Masahiro; Nishio, Nobuhiro; Takeshita, Tatsuya

2015-01-01

We designed a scale to gauge smartphone dependence and assessed its reliability and validity. A prototype self-rating smartphone-dependence scale was tested on 133 medical students who use smartphones more frequently than other devices to access web pages. Each response was scored on a Likert scale (0, 1, 2, 3), with higher scores indicating greater dependence. To select items for the final scale, exploratory factor analysis was conducted. On the basis of factor analysis results, we designed the Wakayama Smartphone-Dependence Scale (WSDS) comprising 21 items with 3 subscales: immersion in Internet communication; using a smartphone for extended periods of time and neglecting social obligations and other tasks; using a smartphone while doing something else and neglect of etiquette. Our analysis confirmed the validity of the different elements of the WSDS: the reliability coefficient (Cronbach's alpha) values of all subscales and total WSDS were from 0.79 to 0.83 and 0.88, respectively. These findings suggest that the WSDS is a useful tool for rating smartphone dependence.

Care dependency of hospitalized children: testing the Care Dependency Scale for Paediatrics in a cross-cultural comparison.

Science.gov (United States)

Tork, Hanan; Dassen, Theo; Lohrmann, Christa

2009-02-01

This paper is a report of a study to examine the psychometric properties of the Care Dependency Scale for Paediatrics in Germany and Egypt and to compare the care dependency of school-age children in both countries. Cross-cultural differences in care dependency of older adults have been documented in the literature, but little is known about the differences and similarities with regard to children's care dependency in different cultures. A convenience sample of 258 school-aged children from Germany and Egypt participated in the study in 2005. The reliability of the Care Dependency Scale for Paediatrics was assessed in terms of internal consistency and interrater reliability. Factor analysis (principal component analysis) was employed to verify the construct validity. A Visual Analogue Scale was used to investigate the criterion-related validity. Good internal consistency was detected both for the Arabic and German versions. Factor analysis revealed one factor for both versions. A Pearson's correlation between the Care Dependency Scale for Paediatrics and Visual Analogue Scale was statistically significant for both versions indicating criterion-related validity. Statistically significant differences between the participants were detected regarding the mean sum score on the Care Dependency Scale for Paediatrics. The Care Dependency Scale for Paediatrics is a reliable and valid tool for assessing the care dependency of children and is recommended for assessing the care dependency of children from different ethnic origins. Differences in care dependency between German and Egyptian children were detected, which might be due to cultural differences.

Study of heavy quarkonium with energy dependent potential

International Nuclear Information System (INIS)

Gupta, Pramila; Mehrotra, I

2009-01-01

It is well known that charmonium and bottonium states can be calculated by using a nonrelativistic Schrodinger equation. The basic reasons are: 1) the mass of charm and bottom quarks is much larger than QCD scale, which makes this system free of strong normalization effects and 2) the binding energy is small compared to the mass energy ψ and γ states in terms of nonrelativistic qq system governed by more or less phenomenological potentials. In the present work we have studied mass spectra of charmonium and bottonium using the following energy dependent model in the framework of nonrelativistic Schrodinger equation

Effect of the δ-potential on spin-dependent electron tunneling in double barrier semiconductor heterostructure

Science.gov (United States)

Chandrasekar, L. Bruno; Gnanasekar, K.; Karunakaran, M.

2018-06-01

The effect of δ-potential was studied in GaAs/Ga0.6Al0·4As double barrier heterostructure with Dresselhaus spin-orbit interaction. The role of barrier height and position of the δ- potential in the well region was analysed on spin-dependent electron tunneling using transfer matrix method. The spin-separation between spin-resonances on energy scale depends on both height and position of the δ- potential, whereas the tunneling life time of electrons highly influenced by the position of the δ- potential and not on the height. These results might be helpful for the fabrication of spin-filters.

Grizzly bear habitat selection is scale dependent.

Science.gov (United States)

Ciarniello, Lana M; Boyce, Mark S; Seip, Dale R; Heard, Douglas C

2007-07-01

The purpose of our study is to show how ecologists' interpretation of habitat selection by grizzly bears (Ursus arctos) is altered by the scale of observation and also how management questions would be best addressed using predetermined scales of analysis. Using resource selection functions (RSF) we examined how variation in the spatial extent of availability affected our interpretation of habitat selection by grizzly bears inhabiting mountain and plateau landscapes. We estimated separate models for females and males using three spatial extents: within the study area, within the home range, and within predetermined movement buffers. We employed two methods for evaluating the effects of scale on our RSF designs. First, we chose a priori six candidate models, estimated at each scale, and ranked them using Akaike Information Criteria. Using this method, results changed among scales for males but not for females. For female bears, models that included the full suite of covariates predicted habitat use best at each scale. For male bears that resided in the mountains, models based on forest successional stages ranked highest at the study-wide and home range extents, whereas models containing covariates based on terrain features ranked highest at the buffer extent. For male bears on the plateau, each scale estimated a different highest-ranked model. Second, we examined differences among model coefficients across the three scales for one candidate model. We found that both the magnitude and direction of coefficients were dependent upon the scale examined; results varied between landscapes, scales, and sexes. Greenness, reflecting lush green vegetation, was a strong predictor of the presence of female bears in both landscapes and males that resided in the mountains. Male bears on the plateau were the only animals to select areas that exposed them to a high risk of mortality by humans. Our results show that grizzly bear habitat selection is scale dependent. Further, the

Scale dependence and small-x behaviour of polarized parton distributions

International Nuclear Information System (INIS)

Ball, R.D.; Forte, S.; Ridolfi, G.

1995-01-01

We discuss perturbative evolution of the polarized structure function g 1 in the (x, Q 2 ) plane, with special regard to the small-x region. We determine g 1 in terms of polarized quark and gluon distributions using coefficient functions to order α s . At small x g 1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution. ((orig.))

Scale dependence and small x behaviour of polarized parton distributions

CERN Document Server

Ball, R D; Ridolfi, G; Forte, S; Ridolfi, G

1995-01-01

We discuss perturbative evolution of the polarized structure function g_1 in the (x,Q^2) plane, with special regard to the small-x region. We determine g_1 in terms of polarized quark and gluon distributions using coefficient functions to order alpha_s. At small x g_1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution.

Neutrino masses, scale-dependent growth, and redshift-space distortions

Energy Technology Data Exchange (ETDEWEB)

Hernández, Oscar F., E-mail: oscarh@physics.mcgill.ca [Marianopolis College, 4873 Westmount Ave., Westmount, QC H3Y 1X9 (Canada)

2017-06-01

Massive neutrinos leave a unique signature in the large scale clustering of matter. We investigate the wavenumber dependence of the growth factor arising from neutrino masses and use a Fisher analysis to determine the aspects of a galaxy survey needed to measure this scale dependence.

Anomalous scaling in an age-dependent branching model.

Science.gov (United States)

Keller-Schmidt, Stephanie; Tuğrul, Murat; Eguíluz, Víctor M; Hernández-García, Emilio; Klemm, Konstantin

2015-02-01

We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age τ as τ(-α). Depending on the exponent α, the scaling of tree depth with tree size n displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition (α=1) tree depth grows as (logn)(2). This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus providing a theoretical support for age-dependent speciation and associating it to the occurrence of a critical point.

[Creation of a scale for evaluating attitudes of partners toward alcohol dependency].

Science.gov (United States)

Sugawara, Tazuko; Morita, Noriaki; Nakatani, Youji

2013-12-01

The aim of this study was to develop a scale to evaluate characteristics of how alcohol-dependent people perceive the attitudes of their partners toward alcohol dependency. Based on previous research, we created the "Attitudes of partners toward alcohol dependency" scale, from the perspective of the alcohol dependent individual. Using the new scale, 71 alcohol-dependent people (52 men, 19 women) were surveyed after obtaining their consent, and the reliability and validity of the scale were tested. The results identified 3 factors, "indifference", "acceptance" and "hypersensitivity", and factorial validity was verified. Relatively high reliability was obtained on each sub-scale (alpha = .60-.82). Furthermore, correlations were obtained with the alcohol-dependency "Denial and Awareness Scale (for alcohol-dependent people)" and with the 13-item "Usefulness of heterosexual love relations for recovery from alcohol dependency" questionnaire, which includes content on "beneficial" or "obstructive" to recovery, and with the satisfaction and the importance of relations. This demonstrates that the "Attitudes of partners toward alcohol dependency" scale has reliability and criterion-related validity. The scale facilitates evaluation of types of attitudes of partners toward alcohol dependency, and may thus be useful as one tool for investigating the influence of partners in heterosexual love relationships for recovery, and for providing advice.

Strong orientation dependence of surface mass density profiles of dark haloes at large scales

Science.gov (United States)

Osato, Ken; Nishimichi, Takahiro; Oguri, Masamune; Takada, Masahiro; Okumura, Teppei

2018-06-01

We study the dependence of surface mass density profiles, which can be directly measured by weak gravitational lensing, on the orientation of haloes with respect to the line-of-sight direction, using a suite of N-body simulations. We find that, when major axes of haloes are aligned with the line-of-sight direction, surface mass density profiles have higher amplitudes than those averaged over all halo orientations, over all scales from 0.1 to 100 Mpc h-1 we studied. While the orientation dependence at small scales is ascribed to the halo triaxiality, our results indicate even stronger orientation dependence in the so-called two-halo regime, up to 100 Mpc h-1. The orientation dependence for the two-halo term is well approximated by a multiplicative shift of the amplitude and therefore a shift in the halo bias parameter value. The halo bias from the two-halo term can be overestimated or underestimated by up to {˜ } 30 per cent depending on the viewing angle, which translates into the bias in estimated halo masses by up to a factor of 2 from halo bias measurements. The orientation dependence at large scales originates from the anisotropic halo-matter correlation function, which has an elliptical shape with the axis ratio of ˜0.55 up to 100 Mpc h-1. We discuss potential impacts of halo orientation bias on other observables such as optically selected cluster samples and a clustering analysis of large-scale structure tracers such as quasars.

Time-dependent local potential in a Tomonaga-Luttinger liquid

Science.gov (United States)

Kamar, Naushad Ahmad; Giamarchi, Thierry

2017-12-01

We study the energy deposition in a one-dimensional interacting quantum system with a pointlike potential modulated in amplitude. The pointlike potential at position x =0 has a constant part and a small oscillation in time with a frequency ω . We use bosonization, renormalization group, and linear response theory to calculate the corresponding energy deposition. It exhibits a power law behavior as a function of the frequency that reflects the Tomonaga-Luttinger liquid (TLL) nature of the system. Depending on the interactions in the system, characterized by the TLL parameter K of the system, a crossover between weak and strong coupling for the backscattering due to the potential is possible. We compute the frequency scale ω*, at which such crossover exists. We find that the energy deposition due to the backscattering shows different exponents for K >1 and K <1 . We discuss possible experimental consequences, in the context of cold atomic gases, of our theoretical results.

Validity and factor structure of the bodybuilding dependence scale.

Science.gov (United States)

Smith, D; Hale, B

2004-04-01

To investigate the factor structure, validity, and reliability of the bodybuilding dependence scale and to investigate differences in bodybuilding dependence between men and women and competitive and non-competitive bodybuilders. Seventy two male competitive bodybuilders, 63 female competitive bodybuilders, 87 male non-competitive bodybuilders, and 63 non-competitive female bodybuilders completed the bodybuilding dependence scale (BDS), the exercise dependence questionnaire (EDQ), and the muscle dysmorphia inventory (MDI). Confirmatory factor analysis of the BDS supported a three factor model of bodybuilding dependence, consisting of social dependence, training dependence, and mastery dependence (Q = 3.16, CFI = 0.98, SRMR = 0.04). Internal reliability of all three subscales was high (Cronbach's alpha = 0.92, 0.92, and 0.93 respectively). Significant (pbodybuilders scored significantly (pbodybuilders. However, there were no significant sex differences on any of the BDS subscales (p>0.05). The three factor BDS appears to be a reliable and valid measure of bodybuilding dependence. Symptoms of bodybuilding dependence are more prevalent in competitive bodybuilders than non-competitive ones, but there are no significant sex differences in bodybuilding dependence.

Uncertainty Quantification in Scale-Dependent Models of Flow in Porous Media: SCALE-DEPENDENT UQ

Energy Technology Data Exchange (ETDEWEB)

Tartakovsky, A. M. [Computational Mathematics Group, Pacific Northwest National Laboratory, Richland WA USA; Panzeri, M. [Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, Milano Italy; Tartakovsky, G. D. [Hydrology Group, Pacific Northwest National Laboratory, Richland WA USA; Guadagnini, A. [Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, Milano Italy

2017-11-01

Equations governing flow and transport in heterogeneous porous media are scale-dependent. We demonstrate that it is possible to identify a support scale $\\eta^*$, such that the typically employed approximate formulations of Moment Equations (ME) yield accurate (statistical) moments of a target environmental state variable. Under these circumstances, the ME approach can be used as an alternative to the Monte Carlo (MC) method for Uncertainty Quantification in diverse fields of Earth and environmental sciences. MEs are directly satisfied by the leading moments of the quantities of interest and are defined on the same support scale as the governing stochastic partial differential equations (PDEs). Computable approximations of the otherwise exact MEs can be obtained through perturbation expansion of moments of the state variables in orders of the standard deviation of the random model parameters. As such, their convergence is guaranteed only for the standard deviation smaller than one. We demonstrate our approach in the context of steady-state groundwater flow in a porous medium with a spatially random hydraulic conductivity.

Parametrization of complex absorbing potentials for time-dependent quantum dynamics

International Nuclear Information System (INIS)

Vibok, A.; Balint-Kurti, G.G.

1992-01-01

Five different forms of complex absorbing potentials are examined and compared. Such potentials are needed to absorb wavepackets near the edges of grids in time-dependent quantum dynamical calculations. The extent to which the different potentials transmit or reflect an incident wavepacket is quantified, and optimal potential parameters to minimize both the reflection and transmission for each type of potential are derived. A rigorously derived scaling procedure, which permits the derivation of optimal potential parameters for use with any chosen mass or kinetic energy from those optimized for different conditions, is described. Tables are also presented which permit the immediate selection of the parameters for an absorbing potential of a particular form so as to allow a preselected (very small) degree of transmitted plus reflected probability to be attained. It is always desirable to devote a minimal region to the absorbing potential, while at the same time effectively absorbing all of the wavepacket and neither transmitting nor reflecting any of it. The tables presented here enable the use to easily select the potential parameters he will require to attain these goals. 23 refs., 7 figs., 4 tabs

Time scale dependent negative emission potential of forests and biomass plantations via wood burial, torrefied biomass, biochar and pyrogas condensate sequestration in soil

Science.gov (United States)

Schmidt, Hans-Peter; Kammann, Claudia; Lucht, Wolfgang; Gerten, Dieter; Foidl, Nikolaus

2017-04-01

The efficiency of Negative Emission Technologies (NET) is dependent on (1) the transformation of the biomass carbon into a form that can be sequestered, (2) the mean residence time of the sequestered carbon, (3) the regrowth and thus carbon re-accumulation of the harvested biomass, and (4) the positive or negative priming of soil carbon. These four parameters define the time scale dependent C-balance of various NET-Systems and permit a global economic and environmental evaluation. As far as geologic CO2 storage is considered to be feasible with close to zero losses and if the energy for transport, transformation and disposal is taken from the process bioenergy, conventional BE-CCS has a C sequestration potential of 50 - 70 % depending on the type of biomass and the technology used. Beside unknown risks of deep stored CO2 and high costs, regrowth of C-accumulating biomass is hampered in the long-term as not only carbon but also essential soil nutrients are mined. Under this scenario, biomass regrowth is expected to slow down and soil carbon content to decrease. These factors enlarge the time horizon until a BE-CCS system becomes carbon neutral and eventual carbon negative (when biomass regrowth exceeds the difference between the harvested biomass carbon and BE-CCS stored carbon). Thermal treatment of biomass under a low oxygen regime (torrefaction, pyrolysis, gasification) can transform up to 85% of biomass carbon into various solid and liquid forms of recalcitrant carbon that can be sequestered. Depending on the process parameters and temperature, the mean residence time of the torrefied or pyrolysed biomass can last from several decennials to centennials when applied to the soil of the biomass production site. The carbon can thus be stored at comparatively low costs within the ecosystem itself. As the thermal treatment preserves most of the biomass-accumulated nutrients (except N), natural nutrient cycles are maintained within the biomass system. Depending on the

A reliability and utility study of the Care Dependency Scale

NARCIS (Netherlands)

Dijkstra, A.; Buist, G.; Moorer, P.; Dassen, T.

2000-01-01

The purpose of this study was to examine the reliability and utility of the Care Dependency Scale (CDS). This 15-item scale has been developed recently for assessing the care dependency of demented or menially handicapped inpatients. Data for this study were collected from 153 demented and 139

Estimating the density-scaling exponent of a monatomic liquid from its pair potential

DEFF Research Database (Denmark)

Bøhling, Lasse; Bailey, Nicholas; Schrøder, Thomas

2014-01-01

This paper investigates two conjectures for calculating the density dependence of the density-scaling exponent γ of a single-component, pair-potential liquid with strong virial potential-energy correlations. The first conjecture gives an analytical expression for γ directly in terms of the pair...... potential. The second conjecture is a refined version of this involving the most likely nearest-neighbor distance determined from the pair-correlation function. The conjectures are tested by simulations of three systems, one of which is the standard Lennard-Jones liquid. While both expressions give...

Energy dependence of nonlocal optical potentials

Science.gov (United States)

Lovell, A. E.; Bacq, P.-L.; Capel, P.; Nunes, F. M.; Titus, L. J.

2017-11-01

Recently, a variety of studies have shown the importance of including nonlocality in the description of reactions. The goal of this work is to revisit the phenomenological approach to determining nonlocal optical potentials from elastic scattering. We perform a χ2 analysis of neutron elastic scattering data off 40Ca, 90Zr, and 208Pb at energies E ≈5 -40 MeV, assuming a Perey and Buck [Nucl. Phys. 32, 353 (1962), 10.1016/0029-5582(62)90345-0] or Tian et al. [Int. J. Mod. Phys. E 24, 1550006 (2015), 10.1142/S0218301315500068] nonlocal form for the optical potential. We introduce energy and asymmetry dependencies in the imaginary part of the potential and refit the data to obtain a global parametrization. Independently of the starting point in the minimization procedure, an energy dependence in the imaginary depth is required for a good description of the data across the included energy range. We present two parametrizations, both of which represent an improvement over the original potentials for the fitted nuclei as well as for other nuclei not included in our fit. Our results show that, even when including the standard Gaussian nonlocality in optical potentials, a significant energy dependence is required to describe elastic-scattering data.

Solitary wave dynamics in time-dependent potentials

International Nuclear Information System (INIS)

Abou Salem, Walid K.

2008-01-01

The long time dynamics of solitary wave solutions of the nonlinear Schroedinger equation in time-dependent external potentials is rigorously studied. To set the stage, the well-posedness of the Cauchy problem for a generalized nonautonomous nonlinear Schroedinger equation with time-dependent nonlinearities and potential is established. Afterward, the dynamics of NLS solitary waves in time-dependent potentials is studied. It is shown that in the space-adiabatic regime where the external potential varies slowly in space compared to the size of the soliton, the dynamics of the center of the soliton is described by Hamilton's equations, plus terms due to radiation damping. Finally, two physical applications are discussed: the first is adiabatic transportation of solitons and the second is the Mathieu instability of trapped solitons due to time-periodic perturbations

Scale dependence of acoustic velocities. An experimental study

Energy Technology Data Exchange (ETDEWEB)

Gotusso, Angelamaria Pillitteri

2001-06-01

Reservoir and overburden data (e.g. seismic, sonic log and core data) are collected at different stages of field development, at different scales, and under different measurement conditions. A more precise reservoir characterization could be obtained by combining all the collected data. Reliable data may also be obtained from drill cuttings. This methodology can give data in quasi-real time, it is easily applicable, and cheap. It is then important, to understand the relationship between results obtained from measurements at different scales. In this Thesis acoustic velocities measured at several different laboratory scales are presented. This experimental study was made in order to give the base for the development of a model aiming to use/combine appropriately the data collected at different scales. The two main aspects analyzed are the experimental limitations due to the decrease in sample size and the significance of measurements in relation to material heterogeneities. Plexiglas, an isotropic, non-dispersive artificial material, with no expected scale effect, was used to evaluate the robustness of the measurement techniques. The results emphasize the importance of the wavelength used with respect to the sample length. If the sample length (L) is at least 5 time bigger than wavelength used ({lambda}), then the measured velocities do not depend on sample size. Leca stone, an artificial isotropic material containing spherical grains was used to evaluate the combined effects of technique, heterogeneities and sample length. The ratio between the scale of the heterogeneities and the sample length has to be taken in to account. In this case velocities increase with decreasing sample length when the ratio L/{lambda} is smaller than 10-15 and at the same time the ratio between sample length and grain size is greater than 10. Measurements on natural rocks demonstrate additional influence of grain mineralogy, shape and orientation. Firenzuola sandstone shows scale and

Nuclear three-body problem and energy-dependent potentials

International Nuclear Information System (INIS)

Abdurakhmanov, A.; Akhmadkhodzhaev, B.; Zubarev, A.L.; Irgaziev, B.F.

1985-01-01

Energy-dependent potentials in the three-body problem are being considered. Three-particle equations for the case of pairing energy-dependent potentials are generalized and the problems related to this ambiguous generalization are investigated. In terms of the equations obtained the tritium binding energy and vertex coupling constants (Tdn) and (Tdν) are evaluated. The binding energy and, especially, coupling constants are shown to be sensitive to a shape of the energy-dependent potential

Validity and factor structure of the bodybuilding dependence scale

OpenAIRE

Smith, D; Hale, B

2004-01-01

Objectives: To investigate the factor structure, validity, and reliability of the bodybuilding dependence scale and to investigate differences in bodybuilding dependence between men and women and competitive and non-competitive bodybuilders.

New parametrization for the scale dependent growth function in general relativity

International Nuclear Information System (INIS)

Dent, James B.; Dutta, Sourish; Perivolaropoulos, Leandros

2009-01-01

We study the scale-dependent evolution of the growth function δ(a,k) of cosmological perturbations in dark energy models based on general relativity. This scale dependence is more prominent on cosmological scales of 100h -1 Mpc or larger. We derive a new scale-dependent parametrization which generalizes the well-known Newtonian approximation result f 0 (a)≡(dlnδ 0 /dlna)=Ω(a) γ (γ=(6/11) for ΛCDM) which is a good approximation on scales less than 50h -1 Mpc. Our generalized parametrization is of the form f(a)=(f 0 (a)/1+ξ(a,k)), where ξ(a,k)=(3H 0 2 Ω 0m )/(ak 2 ). We demonstrate that this parametrization fits the exact result of a full general relativistic evaluation of the growth function up to horizon scales for both ΛCDM and dynamical dark energy. In contrast, the scale independent parametrization does not provide a good fit on scales beyond 5% of the horizon scale (k≅0.01h -1 Mpc).

The care dependency scale for measuring basic human needs: an international comparison.

Science.gov (United States)

Dijkstra, Ate; Yönt, Gülendam Hakverdioğlu; Korhan, Esra Akin; Muszalik, Marta; Kędziora-Kornatowska, Kornelia; Suzuki, Mizue

2012-10-01

To report a study conducted to compare the utility of the care dependency scale across four countries. The care dependency scale provides a framework for assessing the needs of institutionalized patients for nursing care. Henderson's components of nursing care have been used to specify the variable aspects of the concept of care dependency and to develop the care dependency scale items. The study used a cross-cultural survey design. Patients were recruited from four different countries: Japan, The Netherlands, Poland and Turkey. In each of the participating countries, basic human needs were assessed by nurses using a translated version of the original Dutch care dependency scale. Psychometric properties in terms of reliability and validity of the care dependency scale have been assessed using Cronbach's alpha, Guttman's lambda-2, inter-item correlation and principal components analysis. Data were collected in 2008 and 2009. High internal consistency values were demonstrated. Principal component analysis confirmed the one-factor model reported in earlier studies. Outcomes confirm Henderson's idea that human needs are fundamental appearing in every patient-nurse relationship, independent of the patient's age, the type of care setting and/or cultural background. The psychometric characteristics of the care dependency scale make this instrument very useful for comparative research across countries. © 2012 Blackwell Publishing Ltd.

Potential Size of and Value Proposition for H2@Scale Concept

Energy Technology Data Exchange (ETDEWEB)

Ruth, Mark F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jadun, Paige [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pivovar, Bryan S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Elgowainy, Amgad [Argonne National Laboratory

2017-11-09

The H2@Scale concept is focused on developing hydrogen as an energy carrier and using hydrogen's properties to improve the national energy system. Specifically hydrogen has the abilities to (1) supply a clean energy source for industry and transportation and (2) increase the profitability of variable renewable electricity generators such as wind turbines and solar photovoltaic (PV) farms by providing value for otherwise potentially-curtailed electricity. Thus the concept also has the potential to reduce oil dependency by providing a low-carbon fuel for fuel cell electric vehicles (FCEVs), reduce emissions of carbon dioxide and pollutants such as NOx, and support domestic energy production, manufacturing, and U.S. economic competitiveness. The analysis reported here focuses on the potential market size and value proposition for the H2@Scale concept. It involves three analysis phases: 1. Initial phase estimating the technical potential for hydrogen markets and the resources required to meet them; 2. National-scale analysis of the economic potential for hydrogen and the interactions between willingness to pay by hydrogen users and the cost to produce hydrogen from various sources; and 3. In-depth analysis of spatial and economic issues impacting hydrogen production and utilization and the markets. Preliminary analysis of the technical potential indicates that the technical potential for hydrogen use is approximately 60 million metric tons (MMT) annually for light duty FCEVs, heavy duty vehicles, ammonia production, oil refining, biofuel hydrotreating, metals refining, and injection into the natural gas system. The technical potential of utility-scale PV and wind generation independently are much greater than that necessary to produce 60 MMT / year hydrogen. Uranium, natural gas, and coal reserves are each sufficient to produce 60 MMT / year hydrogen in addition to their current uses for decades to centuries. National estimates of the economic potential of

Anomalous scaling in an age-dependent branching model

OpenAIRE

Keller-Schmidt, Stephanie; Tugrul, Murat; Eguiluz, Victor M.; Hernandez-Garcia, Emilio; Klemm, Konstantin

2010-01-01

We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age $\\tau$ as $\\tau^{-\\alpha}$. Depending on the exponent $\\alpha$, the scaling of tree depth with tree size $n$ displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition ($\\alpha=1$) tree depth grows as $(\\log n)^2$. This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus p...

Scale-dependent seasonal pool habitat use by sympatric Wild Brook Trout and Brown Trout populations

Science.gov (United States)

Davis, Lori A.; Wagner, Tyler

2016-01-01

Sympatric populations of native Brook Trout Salvelinus fontinalis and naturalized Brown Trout Salmo truttaexist throughout the eastern USA. An understanding of habitat use by sympatric populations is of importance for fisheries management agencies because of the close association between habitat and population dynamics. Moreover, habitat use by stream-dwelling salmonids may be further complicated by several factors, including the potential for fish to display scale-dependent habitat use. Discrete-choice models were used to (1) evaluate fall and early winter daytime habitat use by sympatric Brook Trout and Brown Trout populations based on available residual pool habitat within a stream network and (2) assess the sensitivity of inferred habitat use to changes in the spatial scale of the assumed available habitat. Trout exhibited an overall preference for pool habitats over nonpool habitats; however, the use of pools was nonlinear over time. Brook Trout displayed a greater preference for deep residual pool habitats than for shallow pool and nonpool habitats, whereas Brown Trout selected for all pool habitat categories similarly. Habitat use by both species was found to be scale dependent. At the smallest spatial scale (50 m), habitat use was primarily related to the time of year and fish weight. However, at larger spatial scales (250 and 450 m), habitat use varied over time according to the study stream in which a fish was located. Scale-dependent relationships in seasonal habitat use by Brook Trout and Brown Trout highlight the importance of considering scale when attempting to make inferences about habitat use; fisheries managers may want to consider identifying the appropriate spatial scale when devising actions to restore and protect Brook Trout populations and their habitats.

SYMMETRY PROPERTIES OF THE COULOMB POTENTIAL WITH A LINEAR DEPENDENCE ON ENERGY

Directory of Open Access Journals (Sweden)

Radu Budaca

2017-12-01

Full Text Available The D-dimensional Schr ̈odinger equation for a Coulomb potential with a coupling constant depending linearly on energy is analytically solved. The energy spectrum in the asymptotic regime of the slope parameter is found to be fully determined up to a scale only by its quantum numbers. The raising and lowering operators for this limiting model are determined from the recurrence properties of the associated solutions. It is shown that they satisfy the commutation relations of an SU(1,1 algebra and act on wave-functions which are normalized differently from the case of the usual bound state problem for an energy independent Coulomb potential.

Movement reveals scale dependence in habitat selection of a large ungulate

Science.gov (United States)

Northrup, Joseph; Anderson, Charles R.; Hooten, Mevin B.; Wittemyer, George

2016-01-01

Ecological processes operate across temporal and spatial scales. Anthropogenic disturbances impact these processes, but examinations of scale dependence in impacts are infrequent. Such examinations can provide important insight to wildlife–human interactions and guide management efforts to reduce impacts. We assessed spatiotemporal scale dependence in habitat selection of mule deer (Odocoileus hemionus) in the Piceance Basin of Colorado, USA, an area of ongoing natural gas development. We employed a newly developed animal movement method to assess habitat selection across scales defined using animal-centric spatiotemporal definitions ranging from the local (defined from five hour movements) to the broad (defined from weekly movements). We extended our analysis to examine variation in scale dependence between night and day and assess functional responses in habitat selection patterns relative to the density of anthropogenic features. Mule deer displayed scale invariance in the direction of their response to energy development features, avoiding well pads and the areas closest to roads at all scales, though with increasing strength of avoidance at coarser scales. Deer displayed scale-dependent responses to most other habitat features, including land cover type and habitat edges. Selection differed between night and day at the finest scales, but homogenized as scale increased. Deer displayed functional responses to development, with deer inhabiting the least developed ranges more strongly avoiding development relative to those with more development in their ranges. Energy development was a primary driver of habitat selection patterns in mule deer, structuring their behaviors across all scales examined. Stronger avoidance at coarser scales suggests that deer behaviorally mediated their interaction with development, but only to a degree. At higher development densities than seen in this area, such mediation may not be possible and thus maintenance of sufficient

Exploiting scale dependence in cosmological averaging

International Nuclear Information System (INIS)

Mattsson, Teppo; Ronkainen, Maria

2008-01-01

We study the role of scale dependence in the Buchert averaging method, using the flat Lemaitre–Tolman–Bondi model as a testing ground. Within this model, a single averaging scale gives predictions that are too coarse, but by replacing it with the distance of the objects R(z) for each redshift z, we find an O(1%) precision at z<2 in the averaged luminosity and angular diameter distances compared to their exact expressions. At low redshifts, we show the improvement for generic inhomogeneity profiles, and our numerical computations further verify it up to redshifts z∼2. At higher redshifts, the method breaks down due to its inability to capture the time evolution of the inhomogeneities. We also demonstrate that the running smoothing scale R(z) can mimic acceleration, suggesting that it could be at least as important as the backreaction in explaining dark energy as an inhomogeneity induced illusion

Scale Dependence of Spatiotemporal Intermittence of Rain

Science.gov (United States)

Kundu, Prasun K.; Siddani, Ravi K.

2011-01-01

It is a common experience that rainfall is intermittent in space and time. This is reflected by the fact that the statistics of area- and/or time-averaged rain rate is described by a mixed distribution with a nonzero probability of having a sharp value zero. In this paper we have explored the dependence of the probability of zero rain on the averaging space and time scales in large multiyear data sets based on radar and rain gauge observations. A stretched exponential fannula fits the observed scale dependence of the zero-rain probability. The proposed formula makes it apparent that the space-time support of the rain field is not quite a set of measure zero as is sometimes supposed. We also give an ex.planation of the observed behavior in tenus of a simple probabilistic model based on the premise that rainfall process has an intrinsic memory.

Permeability dependence of streaming potential coefficient in porous media

NARCIS (Netherlands)

Thanh, L.D.; Sprik, R.

2015-01-01

In theory, the streaming potential coefficient depends not only on the zeta potential but also on the permeability of the rocks that partially determines the surface conductivity of the rocks. However, in practice, it is hard to show the permeability dependence of streaming potential coefficients

Commonness of Amazonian palm (Arecaceae) species: Cross-scale links and potential determinants

DEFF Research Database (Denmark)

Kristiansen, Thea; Svenning, J.-C.; Grández, César

2009-01-01

was positively related to topographic niche breadth. Stem height correlated with continental range size and was the only species life-history trait related to any commonness measure. Distance from the study area to a species' range centre did not influence any of the commonness measures. The factors determining......The mechanisms that cause variation in commonness (abundances and range sizes) of species remain debated in ecology, and a repeatedly observed pattern is the positive relation between local abundances and larger scale range sizes. We used the Amazonian palm species (Arecaceae) to investigate...... the dependence between and potential determinants of commonness across three (local, landscape, continental) spatial scales. Commonness at the smaller scales (local abundance, landscape frequency) was estimated using data from 57 transects (5 × 500 m) in primary, non-inundated (terra firme) rainforest...

Strongly scale-dependent CMB dipolar asymmetry from super-curvature fluctuations

Energy Technology Data Exchange (ETDEWEB)

Byrnes, Christian [Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Domènech, Guillem; Sasaki, Misao [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Takahashi, Tomo, E-mail: C.Byrnes@sussex.ac.uk, E-mail: guillem.domenech@yukawa.kyoto-u.ac.jp, E-mail: misao@yukawa.kyoto-u.ac.jp, E-mail: tomot@cc.saga-u.ac.jp [Department of Physics, Saga University, Saga 840-8502 (Japan)

2016-12-01

We reconsider the observed CMB dipolar asymmetry in the context of open inflation, where a supercurvature mode might survive the bubble nucleation. If such a supercurvature mode modulates the amplitude of the curvature power spectrum, it would easily produce an asymmetry in the power spectrum. We show that current observational data can be accommodated in a three-field model, with simple quadratic potentials and a non-trivial field-space metric. Despite the presence of three fields, we believe this model is so far the simplest that can match current observations. We are able to match the observed strong scale dependence of the dipolar asymmetry, without a fine tuning of initial conditions, breaking slow roll or adding a feature to the evolution of any field.

Reliability and validity of the Severity of Dependence Scale for detecting cannabis dependence in frequent cannabis users

NARCIS (Netherlands)

van der Pol, P.; Liebregts, N.; de Graaf, R.; Korf, D.J.; van den Brink, W.; van Laar, M.

2013-01-01

The Severity of Dependence Scale (SDS) measures with five items the degree of psychological dependence on several illicit drugs, including cannabis. Its psychometric properties have not yet been examined in young adult frequent cannabis users, an eminently high-risk group for cannabis dependence.

Atomistic simulations of materials: Methods for accurate potentials and realistic time scales

Science.gov (United States)

Tiwary, Pratyush

This thesis deals with achieving more realistic atomistic simulations of materials, by developing accurate and robust force-fields, and algorithms for practical time scales. I develop a formalism for generating interatomic potentials for simulating atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high-energy collisions. This is done by fitting against an extensive database of ab initio results, as well as to experimental measurements for mixed oxide nuclear fuels. The applicability of these interactions to a variety of mixed environments beyond the fitting domain is also assessed. The employed formalism makes these potentials applicable across all interatomic distances without the need for any ambiguous splining to the well-established short-range Ziegler-Biersack-Littmark universal pair potential. We expect these to be reliable potentials for carrying out damage simulations (and molecular dynamics simulations in general) in nuclear fuels of varying compositions for all relevant atomic collision energies. A hybrid stochastic and deterministic algorithm is proposed that while maintaining fully atomistic resolution, allows one to achieve milliseconds and longer time scales for several thousands of atoms. The method exploits the rare event nature of the dynamics like other such methods, but goes beyond them by (i) not having to pick a scheme for biasing the energy landscape, (ii) providing control on the accuracy of the boosted time scale, (iii) not assuming any harmonic transition state theory (HTST), and (iv) not having to identify collective coordinates or interesting degrees of freedom. The method is validated by calculating diffusion constants for vacancy-mediated diffusion in iron metal at low temperatures, and comparing against brute-force high temperature molecular dynamics. We also calculate diffusion constants for vacancy diffusion in tantalum metal, where we compare against low-temperature HTST as well

Dynamical properties of a particle in a time-dependent double-well potential

International Nuclear Information System (INIS)

Leonel, Edson D; McClintock, P V E

2004-01-01

Some chaotic properties of a classical particle interacting with a time-dependent double-square-well potential are studied. The dynamics of the system is characterized using a two-dimensional nonlinear area-preserving map. Scaling arguments are used to study the chaotic sea in the low-energy domain. It is shown that the distributions of successive reflections and of corresponding successive reflection times obey power laws with the same exponent. If one or both wells move randomly, the particle experiences the phenomenon of Fermi acceleration in the sense that it has unlimited energy growth

Assessment of clean development mechanism potential of large-scale energy efficiency measures in heavy industries

International Nuclear Information System (INIS)

Hayashi, Daisuke; Krey, Matthias

2007-01-01

This paper assesses clean development mechanism (CDM) potential of large-scale energy efficiency measures in selected heavy industries (iron and steel, cement, aluminium, pulp and paper, and ammonia) taking India and Brazil as examples of CDM project host countries. We have chosen two criteria for identification of the CDM potential of each energy efficiency measure: (i) emission reductions volume (in CO 2 e) that can be expected from the measure and (ii) likelihood of the measure passing the additionality test of the CDM Executive Board (EB) when submitted as a proposed CDM project activity. The paper shows that the CDM potential of large-scale energy efficiency measures strongly depends on the project-specific and country-specific context. In particular, technologies for the iron and steel industry (coke dry quenching (CDQ), top pressure recovery turbine (TRT), and basic oxygen furnace (BOF) gas recovery), the aluminium industry (point feeder prebake (PFPB) smelter), and the pulp and paper industry (continuous digester technology) offer promising CDM potential

Caffeine and length dependence of staircase potentiation in skeletal muscle.

Science.gov (United States)

Rassier, D E; Tubman, L A; MacIntosh, B R

1998-01-01

Skeletal muscle sensitivity to Ca2+ is greater at long lengths, and this results in an optimal length for twitch contractions that is longer than optimal length for tetanic contractions. Caffeine abolishes this length dependence of Ca2+ sensitivity. Muscle length (ML) also affects the degree of staircase potentiation. Since staircase potentiation is apparently caused by an increased Ca2+ sensitivity of the myofilaments, we tested the hypothesis that caffeine depresses the length dependence of staircase potentiation. In situ isometric twitch contractions of rat gastrocnemius muscle before and after 10 s of 10-Hz stimulation were analyzed at seven different lengths to evaluate the length dependence of staircase potentiation. In the absence of caffeine, length dependence of Ca2+ sensitivity was observed, and the degree of potentiation after 10-Hz stimulation showed a linear decrease with increased length (DT = 1.47 - 0.05 ML, r2 = 0.95, where DT is developed tension). Length dependence of Ca2+ sensitivity was decreased by caffeine when caffeine was administered in amounts estimated to result in 0.5 and 0.75 mM concentrations. Furthermore, the negative slope of the relationship between staircase potentiation and muscle length was diminished at the lower caffeine dose, and the slope was not different from zero after the higher dose (DT = 1.53 - 0.009 ML, r2 = 0.43). Our study shows that length dependence of Ca2+ sensitivity in intact skeletal muscle is diminished by caffeine. Caffeine also suppressed the length dependence of staircase potentiation, suggesting that the mechanism of this length dependence may be closely related to the mechanism for length dependence of Ca2+ sensitivity.

Hemispherical power asymmetry from scale-dependent modulated reheating

International Nuclear Information System (INIS)

McDonald, John

2013-01-01

We propose a new model for the hemispherical power asymmetry of the CMB based on modulated reheating. Non-Gaussianity from modulated reheating can be small enough to satisfy the bound from Planck if the dominant modulation of the inflaton decay rate is linear in the modulating field σ. σ must then acquire a spatially-modulated power spectrum with a red scale-dependence. This can be achieved if the primordial perturbation of σ is generated via tachyonic growth of a complex scalar field. Modulated reheating due to σ then produces a spatially modulated and scale-dependent sub-dominant contribution to the adiabatic density perturbation. We show that it is possible to account for the observed asymmetry while remaining consistent with bounds from quasar number counts, non-Gaussianity and the CMB temperature quadupole. The model predicts that the adiabatic perturbation spectral index and its running will be modified by the modulated reheating component

H2@Scale: Technical and Economic Potential of Hydrogen as an Energy Intermediate

Energy Technology Data Exchange (ETDEWEB)

Ruth, Mark F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jadun, Paige [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pivovar, Bryan S [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-11-09

The H2@Scale concept is focused on developing hydrogen as an energy carrier and using hydrogen's properties to improve the national energy system. Specifically hydrogen has the abilities to (1) supply a clean energy source for industry and transportation and (2) increase the profitability of variable renewable electricity generators such as wind turbines and solar photovoltaic (PV) farms by providing value for otherwise potentially-curtailed electricity. Thus the concept also has the potential to reduce oil dependency by providing a low-carbon fuel for fuel cell electric vehicles (FCEVs), reduce emissions of carbon dioxide and pollutants such as NOx, and support domestic energy production, manufacturing, and U.S. economic competitiveness. The analysis reported here focuses on the potential market size and value proposition for the H2@Scale concept. It involves three analysis phases: 1. Initial phase estimating the technical potential for hydrogen markets and the resources required to meet them; 2. National-scale analysis of the economic potential for hydrogen and the interactions between willingness to pay by hydrogen users and the cost to produce hydrogen from various sources; and 3. In-depth analysis of spatial and economic issues impacting hydrogen production and utilization and the markets. Preliminary analysis of the technical potential indicates that the technical potential for hydrogen use is approximately 60 million metric tons (MMT) annually for light duty FCEVs, heavy duty vehicles, ammonia production, oil refining, biofuel hydrotreating, metals refining, and injection into the natural gas system. The technical potential of utility-scale PV and wind generation independently are much greater than that necessary to produce 60 MMT / year hydrogen. Uranium, natural gas, and coal reserves are each sufficient to produce 60 MMT / year hydrogen in addition to their current uses for decades to centuries. National estimates of the economic potential of

Scale dependency of American marten (Martes americana) habitat relations [Chapter 12

Science.gov (United States)

Andrew J. Shirk; Tzeidle N. Wasserman; Samuel A. Cushman; Martin G. Raphael

2012-01-01

Animals select habitat resources at multiple spatial scales; therefore, explicit attention to scale-dependency when modeling habitat relations is critical to understanding how organisms select habitat in complex landscapes. Models that evaluate habitat variables calculated at a single spatial scale (e.g., patch, home range) fail to account for the effects of...

Testing the Scale Dependence of the Scale Factor $\\sigma_{eff}$ in Double Dijet Production at the LHC

CERN Document Server

Domdey, Svend; Wiedemann, Urs Achim

2010-01-01

The scale factor σ eff is the effective cross section used to characterize the measured rate of inclusive double dijet production in high energy hadron collisions. It is sensitive to the two-parton distributions in the hadronic projectile. In principle, the scale factor depends on the center of mass energy and on the minimal transverse energy of the jets contributing to the double dijet cross section. Here, we point out that proton-proton collisions at the LHC will provide for the first time experimental access to these scale dependences in a logarithmically wide, nominally perturbative kinematic range of minimal transverse energy between 10 GeV and 100 GeV. This constrains the dependence of two-parton distribution functions on parton momentum fractions and parton localization in impact parameter space. Novel information is to be expected about the transverse growth of hadronic distribution functions in the range of semi-hard Bjorken x (0.001 < x < 0.1) and high resolution Q^2. We discuss to what exten...

Nursing-care dependency : Development of an assessment scale for demented and mentally handicapped patients

NARCIS (Netherlands)

Dijkstra, Ate; Buist, Girbe; Dassen, T

1996-01-01

This article describing the first phase in the development of an assessment scale of nursing-care dependency (NCD) for Dutch demented and mentally handicapped patients focuses on the background to the study and the content validation of the nursing-care dependency scale. The scale aims to

Environmentally dependent bond-order potentials: New ...

Indian Academy of Sciences (India)

Environmentally dependent bond-order potentials: New developments and applications ... for modelling amorphous structure we found that the and bond integrals are not only transferable between graphite and diamond structures but they are also strongly anisotropic due to inter-plan bonding between graphite sheets.

Length dependence of staircase potentiation: interactions with caffeine and dantrolene sodium.

Science.gov (United States)

Rassier, D E; MacIntosh, B R

2000-04-01

In skeletal muscle, there is a length dependence of staircase potentiation for which the mechanism is unclear. In this study we tested the hypothesis that abolition of this length dependence by caffeine is effected by a mechanism independent of enhanced Ca2+ release. To test this hypothesis we have used caffeine, which abolishes length dependence of potentiation, and dantrolene sodium, which inhibits Ca2+ release. In situ isometric twitch contractions of rat gastrocnemius muscle before and after 20 s of repetitive stimulation at 5 Hz were analyzed at optimal length (Lo), Lo - 10%, and Lo + 10%. Potentiation was observed to be length dependent, with an increase in developed tension (DT) of 78 +/- 12, 51 +/- 5, and 34 +/- 9% (mean +/- SEM), at Lo - 10%, Lo, and Lo + 10%, respectively. Caffeine diminished the length dependence of activation and suppressed the length dependence of staircase potentiation, giving increases in DT of 65+/-13, 53 +/- 11, and 45 +/- 12% for Lo - 10%, Lo, and Lo + 10%, respectively. Dantrolene administered after caffeine did not reverse this effect. Dantrolene alone depressed the potentiation response, but did not affect the length dependence of staircase potentiation, with increases in DT of 58 +/- 17, 26 +/- 8, and 18 +/- 7%, respectively. This study confirms that there is a length dependence of staircase potentiation in mammalian skeletal muscle which is suppressed by caffeine. Since dantrolene did not alter this suppression of the length dependence of potentiation by caffeine, it is apparently not directly modulated by Ca2+ availability in the myoplasm.

Davydov–Chaban Hamiltonian in presence of time-dependent potential

Energy Technology Data Exchange (ETDEWEB)

Sobhani, Hadi; Hassanabadi, Hassan, E-mail: h.hassanabadi@shahroodut.ac.ir

2016-09-10

In this article, we have investigated collective effects of atomic nuclei in presence of a time-dependent potential in Davydov–Chaban Hamiltonian. Since such potential has an explicit time-dependency, in order to obtain the wave function of considered system, we should face with time-dependent Schrödinger equation. Obtaining the wave function could be possible using Lewis–Riesenfeld dynamical invariant method. Appropriate dynamical invariant has been constructed after determining the wave functions and values, the wave function will obtain.

Non-isomorphic radial wavenumber dependencies of residual zonal flows in ion and electron Larmor radius scales, and effects of initial parallel flow and electromagnetic potentials in a circular tokamak

Science.gov (United States)

Yamagishi, Osamu

2018-04-01

Radial wavenumber dependencies of the residual zonal potential for E × B flow in a circular, large aspect ratio tokamak is investigated by means of the collisionless gyrokinetic simulations of Rosenbluth-Hinton (RH) test and the semi-analytic approach using an analytic solution of the gyrokinetic equation Rosenbluth and Hinton (1998 Phys. Rev. Lett. 80 724). By increasing the radial wavenumber from an ion Larmor radius scale {k}r{ρ }i≲ 1 to an electron Larmor radius scale {k}r{ρ }e≲ 1, the well-known level ˜ O[1/(1+1.6{q}2/\\sqrt{r/{R}0})] is retained, while the level remains O(1) when the wavenumber is decreased from the electron to the ion Larmor radius scale, if physically same adiabatic assumption is presumed for species other than the main species that is treated kinetically. The conclusion is not modified by treating both species kinetically, so that in the intermediate scale between the ion and electron Larmor radius scale it seems difficult to determine the level uniquely. The toroidal momentum conservation property in the RH test is also investigated by including an initial parallel flow in addition to the perpendicular flow. It is shown that by taking a balance between the initial parallel flow and perpendicular flows which include both E × B flow and diamagnetic flow in the initial condition, the mechanical toroidal angular momentum is approximately conserved despite the toroidal symmetry breaking due to the finite radial wavenumber zonal modes. Effect of electromagnetic potentials is also investigated. When the electromagnetic potentials are applied initially, fast oscillations which are faster than the geodesic acoustic modes are introduced in the decay phase of the zonal modes. Although the residual level in the long time limit is not modified, this can make the time required to reach the stationary zonal flows longer and may weaken the effectiveness of the turbulent transport suppression by the zonal flows.

Model-independent test for scale-dependent non-Gaussianities in the cosmic microwave background.

Science.gov (United States)

Räth, C; Morfill, G E; Rossmanith, G; Banday, A J; Górski, K M

2009-04-03

We present a model-independent method to test for scale-dependent non-Gaussianities in combination with scaling indices as test statistics. Therefore, surrogate data sets are generated, in which the power spectrum of the original data is preserved, while the higher order correlations are partly randomized by applying a scale-dependent shuffling procedure to the Fourier phases. We apply this method to the Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background and find signatures for non-Gaussianities on large scales. Further tests are required to elucidate the origin of the detected anomalies.

Scale-dependent bias from the reconstruction of non-Gaussian distributions

International Nuclear Information System (INIS)

Chongchitnan, Sirichai; Silk, Joseph

2011-01-01

Primordial non-Gaussianity introduces a scale-dependent variation in the clustering of density peaks corresponding to rare objects. This variation, parametrized by the bias, is investigated on scales where a linear perturbation theory is sufficiently accurate. The bias is obtained directly in real space by comparing the one- and two-point probability distributions of density fluctuations. We show that these distributions can be reconstructed using a bivariate Edgeworth series, presented here up to an arbitrarily high order. The Edgeworth formalism is shown to be well-suited for ''local'' cubic-order non-Gaussianity parametrized by g NL . We show that a strong scale dependence in the bias can be produced by g NL of order 10 5 , consistent with cosmic microwave background constraints. On a separation length of ∼100 Mpc, current constraints on g NL still allow the bias for the most massive clusters to be enhanced by 20-30% of the Gaussian value. We further examine the bias as a function of mass scale, and also explore the relationship between the clustering and the abundance of massive clusters in the presence of g NL . We explain why the Edgeworth formalism, though technically challenging, is a very powerful technique for constraining high-order non-Gaussianity with large-scale structures.

CMB scale dependent non-Gaussianity from massive gravity during inflation

Energy Technology Data Exchange (ETDEWEB)

Domènech, Guillem; Hiramatsu, Takashi; Lin, Chunshan; Sasaki, Misao [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, 606-8502 (Japan); Shiraishi, Maresuke [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), UTIAS, The University of Tokyo, Chiba, 277-8583 (Japan); Wang, Yi, E-mail: guillem.domenech@yukawa.kyoto-u.ac.jp, E-mail: hiramatz@yukawa.kyoto-u.ac.jp, E-mail: chunshan.lin@yukawa.kyoto-u.ac.jp, E-mail: misao@yukawa.kyoto-u.ac.jp, E-mail: shiraishi-m@t.kagawa-nct.ac.jp, E-mail: phyw@ust.hk [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

2017-05-01

We consider a cosmological model in which the tensor mode becomes massive during inflation, and study the Cosmic Microwave Background (CMB) temperature and polarization bispectra arising from the mixing between the scalar mode and the massive tensor mode during inflation. The model assumes the existence of a preferred spatial frame during inflation. The local Lorentz invariance is already broken in cosmology due to the existence of a preferred rest frame. The existence of a preferred spatial frame further breaks the remaining local SO(3) invariance and in particular gives rise to a mass in the tensor mode. At linear perturbation level, we minimize our model so that the vector mode remains non-dynamical, while the scalar mode is the same as the one in single-field slow-roll inflation. At non-linear perturbation level, this inflationary massive graviton phase leads to a sizeable scalar-scalar-tensor coupling, much greater than the scalar-scalar-scalar one, as opposed to the conventional case. This scalar-scalar-tensor interaction imprints a scale dependent feature in the CMB temperature and polarization bispectra. Very intriguingly, we find a surprizing similarity between the predicted scale dependence and the scale-dependent non-Gaussianities at low multipoles hinted in the WMAP and Planck results.

Antipersistent dynamics in short time scale variability of self-potential signals

Directory of Open Access Journals (Sweden)

M. Ragosta

2000-06-01

Full Text Available Time scale properties of self-potential signals are investigated through the analysis of the second order structure function (variogram, a powerful tool to investigate the spatial and temporal variability of observational data. In this work we analyse two sequences of self-potential values measured by means of a geophysical monitoring array located in a seismically active area of Southern Italy. The range of scales investigated goes from a few minutes to several days. It is shown that signal fluctuations are characterised by two time scale ranges in which self-potential variability appears to follow slightly different dynamical behaviours. Results point to the presence of fractal, non stationary features expressing a long term correlation with scaling coefficients which are the clue of stabilising mechanisms. In the scale ranges in which the series show scale invariant behaviour, self-potentials evolve like fractional Brownian motions with anticorrelated increments typical of processes regulated by negative feedback mechanisms (antipersistence. On scales below about 6 h the strength of such an antipersistence appears to be slightly greater than that observed on larger time scales where the fluctuations are less efficiently stabilised.

Scaling Potential Evapotranspiration with Greenhouse Warming (Invited)

Science.gov (United States)

Scheff, J.; Frierson, D. M.

2013-12-01

Potential evapotranspiration (PET) is a supply-independent measure of the evaporative demand of a terrestrial climate, of basic importance in climatology, hydrology, and agriculture. Future increases in PET from greenhouse warming are often cited as key drivers of global trends toward drought and aridity. The present work computes recent and business-as-usual-future Penman-Monteith (i.e. physically-based) PET fields at 3-hourly resolution in 14 modern global climate models. The %-change in local annual-mean PET over the upcoming century is almost always positive, modally low double-digit in magnitude, usually increasing with latitude, yet quite divergent between models. These patterns are understood as follows. In every model, the global field of PET %-change is found to be dominated by the direct, positive effects of constant-relative-humidity warming (via increasing vapor pressure deficit and increasing Clausius-Clapeyron slope.) This direct-warming term very accurately scales as the PET-weighted (warm-season daytime) local warming, times 5-6% per degree (related to the Clausius-Clapeyron equation), times an analytic factor ranging from about 0.25 in warm climates to 0.75 in cold climates, plus a small correction. With warming of several degrees, this product is of low double-digit magnitude, and the strong temperature dependence gives the latitude dependence. Similarly, the inter-model spread in the amount of warming gives most of the spread in this term. Additional spread in the total change comes from strong disagreement on radiation, relative-humidity, and windspeed changes, which make smaller yet substantial contributions to the full PET %-change fields.

Exploring new scaling regimes for streaming potential and electroviscous effects in a nanocapillary with overlapping electric double layers.

Science.gov (United States)

Das, Siddhartha; Guha, Arnab; Mitra, Sushanta K

2013-12-04

In this paper, we unravel new scaling regimes for streaming potential and electroviscous effects in a nanocapillary with thick overlapping Electric Double Layers (EDLs). We observe that the streaming potential, for a given value of the capillary zeta (ζ) potential, varies with the EDL thickness and a dimensionless parameter R, quantifying the conduction current. Depending on the value of R, variation of the streaming potential with the EDL thickness demonstrates distinct scaling regimes: one can witness a Quadratic Regime where the streaming potential varies as the square of the EDL thickness, a Weak Regime where the streaming potential shows a weaker variation with the EDL thickness, and a Saturation Regime where the streaming potential ceases to vary with the EDL thickness. Effective viscosity, characterizing the electroviscous effect, obeys the variation of the streaming potential for smaller EDL thickness values; however, for larger EDL thickness the electroosmotic flow profile dictates the electroviscous effect, with insignificant contribution of the streaming potential. Copyright © 2013 Elsevier B.V. All rights reserved.

Investigations of grain size dependent sediment transport phenomena on multiple scales

Science.gov (United States)

Thaxton, Christopher S.

Sediment transport processes in coastal and fluvial environments resulting from disturbances such as urbanization, mining, agriculture, military operations, and climatic change have significant impact on local, regional, and global environments. Primarily, these impacts include the erosion and deposition of sediment, channel network modification, reduction in downstream water quality, and the delivery of chemical contaminants. The scale and spatial distribution of these effects are largely attributable to the size distribution of the sediment grains that become eligible for transport. An improved understanding of advective and diffusive grain-size dependent sediment transport phenomena will lead to the development of more accurate predictive models and more effective control measures. To this end, three studies were performed that investigated grain-size dependent sediment transport on three different scales. Discrete particle computer simulations of sheet flow bedload transport on the scale of 0.1--100 millimeters were performed on a heterogeneous population of grains of various grain sizes. The relative transport rates and diffusivities of grains under both oscillatory and uniform, steady flow conditions were quantified. These findings suggest that boundary layer formalisms should describe surface roughness through a representative grain size that is functionally dependent on the applied flow parameters. On the scale of 1--10m, experiments were performed to quantify the hydrodynamics and sediment capture efficiency of various baffles installed in a sediment retention pond, a commonly used sedimentation control measure in watershed applications. Analysis indicates that an optimum sediment capture effectiveness may be achieved based on baffle permeability, pond geometry and flow rate. Finally, on the scale of 10--1,000m, a distributed, bivariate watershed terain evolution module was developed within GRASS GIS. Simulation results for variable grain sizes and for

Responsiveness of the Care Dependency Scale for Rehabilitation (CDS-R).

Science.gov (United States)

Eichhorn-Kissel, Juliane; Dassen, Theo; Lohrmann, Christa

2012-03-01

Around 10% of Western Europe's population suffer from a disability which can entail a decrease of independency and quality of life. However, the lives of these people can be improved by rehabilitative treatment and care. Changing the degree of dependency from dependent to independent is essential in rehabilitation, as is the assessment of these changes. To perform such kind of measurements, assessment instruments have to be responsive. In spite of this concern, responsiveness of assessment instruments is studied to a small extent only. This also applies to the Care Dependency Scale for Rehabilitation (CDS-R), a short assessment instrument measuring the care dependency of patients regarding physical and psychosocial aspects. In this longitudinal-study, the responsiveness of the CDS-R, in general and related to different disease-groups, should be determined. Therefore, a convenience sample of 1564 patients was assessed in an Austrian rehabilitation centre with the scale after admission and before discharge. Responsiveness was determined by descriptive analysis, calculation of effect-sizes and significance tests. Differences between admission and discharge occurred on a statistically significant level for patients who changed. Kazis' effect-sizes can be considered as of small/medium effect for patients who changed (0.24/0.49), and as of large effect according to Liang (0.86/1.46). Eta squared was 0.10/0.19 which can be interpreted as of moderate/large effect for patients who changed. Responsiveness-analyses related to different disease-groups showed constantly large effect-sizes for patients with musculoskeletal-disorders. These results indicate that the CDS-R can detect patient-changes over time and discriminate between patients who change under rehabilitation or not. These aspects argue for the responsiveness of the scale, wherefore the CDS-R seems to be appropriate for the assessment of treatment/health-care effectiveness and the evaluation of individual patient

Radiatively Generating the Higgs Potential and Electroweak Scale via the Seesaw Mechanism.

Science.gov (United States)

Brivio, Ilaria; Trott, Michael

2017-10-06

The minimal seesaw scenario can radiatively generate the Higgs potential to induce electroweak symmetry breaking while supplying an origin of the Higgs vacuum expectation value from an underlying Majorana scale. If the Higgs potential and (derived) electroweak scale have this origin, the heavy SU(3)×SU(2)×U(1)_{Y} singlet states are expected to reside at m_{N}∼10-500  PeV for couplings |ω|∼10^{-4.5}-10^{-6} between the Majorana sector and the standard model. In this framework, the usual challenge of the electroweak scale hierarchy problem with a classically assumed potential is absent as the electroweak scale is not a fundamental scale. The new challenge is the need to generate or accommodate PeV Majorana mass scales while simultaneously suppressing tree-level contributions to the potential in ultraviolet models.

Two-loop scale-invariant scalar potential and quantum effective operators

CERN Document Server

Ghilencea, D.M.

2016-11-29

Spontaneous breaking of quantum scale invariance may provide a solution to the hierarchy and cosmological constant problems. In a scale-invariant regularization, we compute the two-loop potential of a higgs-like scalar $\\phi$ in theories in which scale symmetry is broken only spontaneously by the dilaton ($\\sigma$). Its vev $\\langle\\sigma\\rangle$ generates the DR subtraction scale ($\\mu\\sim\\langle\\sigma\\rangle$), which avoids the explicit scale symmetry breaking by traditional regularizations (where $\\mu$=fixed scale). The two-loop potential contains effective operators of non-polynomial nature as well as new corrections, beyond those obtained with explicit breaking ($\\mu$=fixed scale). These operators have the form: $\\phi^6/\\sigma^2$, $\\phi^8/\\sigma^4$, etc, which generate an infinite series of higher dimensional polynomial operators upon expansion about $\\langle\\sigma\\rangle\\gg \\langle\\phi\\rangle$, where such hierarchy is arranged by {\\it one} initial, classical tuning. These operators emerge at the quantum...

Small scale hydroelectric power potential in Nevada: a preliminary reconnaissance survey

Energy Technology Data Exchange (ETDEWEB)

Cochran, G.F.; Fordham, J.W.; Richard, K.; Loux, R.

1981-04-01

This preliminary reconnaissance survey is intended to: develop a first estimate as to the potential number, location and characteristics of small-scale (50 kW to 15 MW) hydroelectric sites in Nevada; provide a compilation of various Federal and state laws and regulations, including tax and financing regulations, that affect small-scale hydroelectric development and provide information on sources of small-scale hydroelectric generation hardware and consultants/ contractors who do small scale hydroelectric work. The entire survey has been conducted in the office working with various available data bases. The site survey and site evaluation methods used are described, and data are tabulated on the flow, power potential, predicted capital expenditures required, etc. for 61 potential sites with measured flows and for 77 sites with derived flows. A map showing potential site locations is included. (LCL)

Chemical constituents and anti-ulcerogenic potential of the scales of Cynara scolymus (artichoke) heads.

Science.gov (United States)

Nassar, Mahmoud I; Mohamed, Tahia K; Elshamy, Abdelsamed I; El-Toumy, Sayed A; Abdel Lateef, Azza M; Farrag, Abdel-Razik H

2013-08-15

Cynara scolymus L. (Asteraseae) (artichoke) is commonly eaten as a vegetable; its leaves are frequently used in folk medicine in the treatment of hepatitis, hyperlipidaemia, obesity and dyspeptic disorders. The purpose of this study is to determine the chemical composition of the volatile oil and alcoholic extract of artichoke head scales. In addition, the role of the methanol extract as an anti-ulcer agent against ethanol-induced gastric ulcer in rats was evaluated. Six flavonoids and one phenolic acid were obtained from the methanol extract. Also, 37 compounds were identified in the volatile oil, the majority including mono- and sesquiterpenes. The artichoke extracts (200 and 400 mg kg(-1)) significantly (P artichoke induced an increase in gastric mucus production, and a reduction of the depth and severity of mucosal lesions. Artichoke dose-dependently reduced the elevated ethanol gastric malonylaldehyde, and reduced glutathione levels and catalase activity. These results suggest that the head scales of artichoke possess potential anti-ulcer activity. The present paper describes the identification of volatile oil for the first time along with the isolation and identification of the constituents of the methanol extract. Moreover, the high anti-ulcerogenic potential of scales of C. scolymus heads was established here for the first time. © 2013 Society of Chemical Industry.

Exact time-dependent exchange-correlation potentials for strong-field electron dynamics

International Nuclear Information System (INIS)

Lein, Manfred; Kuemmel, Stephan

2005-01-01

By solving the time-dependent Schroedinger equation and inverting the time-dependent Kohn-Sham scheme we obtain the exact time-dependent exchange-correlation potential of density-functional theory for the strong-field dynamics of a correlated system. We demonstrate that essential features of the exact exchange-correlation potential can be related to derivative discontinuities in stationary density-functional theory. Incorporating the discontinuity in a time-dependent density-functional calculation greatly improves the description of the ionization process

Isospin-dependent term in the relativistic microscopic optical potential

International Nuclear Information System (INIS)

Rong Jian; Ma Zhongyu; National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou; Chinese Academy of Sciences, Beijing

2005-01-01

The isospin-dependence of the relativistic microscopic optical potential is investigated in the Dirac Brueckner-Hartree-Fock approach. The isospin part of the microscopic optical potential is emphasized. A local density approximation is adopted for finite nuclei. Taking 208 Pb as example, the difference between proton and neutron optical potentials is studied and compared with the phenomenological Lane Model potential. (authors)

Personality Assessment Inventory scale characteristics and factor structure in the assessment of alcohol dependency.

Science.gov (United States)

Schinka, J A

1995-02-01

Individual scale characteristics and the inventory structure of the Personality Assessment Inventory (PAI; Morey, 1991) were examined by conducting internal consistency and factor analyses of item and scale score data from a large group (N = 301) of alcohol-dependent patients. Alpha coefficients, mean inter-item correlations, and corrected item-total scale correlations for the sample paralleled values reported by Morey for a large clinical sample. Minor differences in the scale factor structure of the inventory from Morey's clinical sample were found. Overall, the findings support the use of the PAI in the assessment of personality and psychopathology of alcohol-dependent patients.

Sensory information in local field potentials and spikes from visual and auditory cortices: time scales and frequency bands.

Science.gov (United States)

Belitski, Andrei; Panzeri, Stefano; Magri, Cesare; Logothetis, Nikos K; Kayser, Christoph

2010-12-01

Studies analyzing sensory cortical processing or trying to decode brain activity often rely on a combination of different electrophysiological signals, such as local field potentials (LFPs) and spiking activity. Understanding the relation between these signals and sensory stimuli and between different components of these signals is hence of great interest. We here provide an analysis of LFPs and spiking activity recorded from visual and auditory cortex during stimulation with natural stimuli. In particular, we focus on the time scales on which different components of these signals are informative about the stimulus, and on the dependencies between different components of these signals. Addressing the first question, we find that stimulus information in low frequency bands (50 Hz), in contrast, is scale dependent, and is larger when the energy is averaged over several hundreds of milliseconds. Indeed, combined analysis of signal reliability and information revealed that the energy of slow LFP fluctuations is well related to the stimulus even when considering individual or few cycles, while the energy of fast LFP oscillations carries information only when averaged over many cycles. Addressing the second question, we find that stimulus information in different LFP bands, and in different LFP bands and spiking activity, is largely independent regardless of time scale or sensory system. Taken together, these findings suggest that different LFP bands represent dynamic natural stimuli on distinct time scales and together provide a potentially rich source of information for sensory processing or decoding brain activity.

The scaling of stress distribution under small scale yielding by T-scaling method and application to prediction of the temperature dependence on fracture toughness

International Nuclear Information System (INIS)

Ishihara, Kenichi; Hamada, Takeshi; Meshii, Toshiyuki

2017-01-01

In this paper, a new method for scaling the crack tip stress distribution under small scale yielding condition was proposed and named as T-scaling method. This method enables to identify the different stress distributions for materials with different tensile properties but identical load in terms of K or J. Then by assuming that the temperature dependence of a material is represented as the stress-strain relationship temperature dependence, a method to predict the fracture load at an arbitrary temperature from the already known fracture load at a reference temperature was proposed. This method combined the T-scaling method and the knowledge “fracture stress for slip induced cleavage fracture is temperature independent.” Once the fracture load is predicted, fracture toughness J c at the temperature under consideration can be evaluated by running elastic-plastic finite element analysis. Finally, the above-mentioned framework to predict the J c temperature dependency of a material in the ductile-to-brittle temperature distribution was validated for 0.55% carbon steel JIS S55C. The proposed framework seems to have a possibility to solve the problem the master curve is facing in the relatively higher temperature region, by requiring only tensile tests. (author)

Scaling and prescaling in quarkonium

International Nuclear Information System (INIS)

Warner, R.C.; Joshi, G.C.

1979-01-01

Recent experiments in the upsilon region indicate the quark mass dependence of quark-antiquark bound state properties. Classes of quark-antiquark potentials exhibiting scaling of energy level spacing with quark mass are presented, and the importance of mass dependence of bound state properties in investigating the nature of the potential is emphasised. The scaling potentials considered are V=V(msup(1/2)r), which exhibits constant level spacing, and V=bmsup(α)rsup(β), and its generalizations, which has scaling of energy levels controlled by the exponents α and β. The class of potentials yielding constant level spacing is shown to be consistent with the interpretation of the state recently observed at 9.46 GeV in e + e - annihilations as a bound state of a new quark and antiquark with esub(p)=1/3

Momentum dependence of the symmetry potential and its influence on nuclear reactions

International Nuclear Information System (INIS)

Feng Zhaoqing

2011-01-01

A Skyrme-type momentum-dependent nucleon-nucleon force distinguishing isospin effect is parametrized and further implemented in the Lanzhou quantum molecular dynamics model, which leads to a splitting of nucleon effective mass in nuclear matter. Based on the isospin- and momentum-dependent transport model, we investigate the influence of momentum-dependent symmetry potential on several isospin-sensitive observables in heavy-ion collisions. It is found that symmetry potentials with and without the momentum dependence but corresponding to the same density dependence of the symmetry energy result in different distributions of the observables. The midrapidity neutron/proton ratios at high transverse momenta and the excitation functions of the total π - /π + and K 0 /K + yields are particularly sensitive to the momentum dependence of the symmetry potential.

The Self-perception of Text-message Dependency Scale (STDS): Psychometric update based on a United States sample.

Science.gov (United States)

Liese, Bruce S; Benau, Erik M; Atchley, Paul; Reed, Derek; Becirevic, Amel; Kaplan, Brent

2018-05-14

Some have suggested that text messaging is an addictive behavior. However, this characterization is uncertain, partly due to lack of well-validated measures of text messaging attitudes and behaviors. One standard instrument for measuring text messaging attitudes and behaviors is the Self-perception of Text-message Dependency Scale (STDS), though the psychometric properties of this scale have only been examined with a sample of Japanese youth. The primary objective of this study was to evaluate the STDS in the United States to determine its utility as a measure of text messaging dependence. We were interested in examining the factor structure and determining the extent to which this scale would correlate with two important outcome measures: motor vehicle accidents (MVAs) and moving violations. We analyzed data from 468 adults (age 18-74; 274 women) recruited via Amazon's Mechanical Turk (mTurk) service. Participants completed the STDS and provided information about their driving-related incidents in the past year. First we performed a confirmatory factor analysis, which supported the instrument's original factor structure. Then we tested the relationship between scores on the STDS and two important variables, MVAs and moving violations. We found that the STDS significantly correlated with both MVAs and moving violations. The present study confirms that the STDS is a potentially useful instrument for studying texting dependence in the United States and with adults of all ages. The instrument may be particularly useful in predicting motor vehicle outcomes.

Bridging asymptotic independence and dependence in spatial exbtremes using Gaussian scale mixtures

KAUST Repository

Huser, Raphaël

2017-06-23

Gaussian scale mixtures are constructed as Gaussian processes with a random variance. They have non-Gaussian marginals and can exhibit asymptotic dependence unlike Gaussian processes, which are asymptotically independent except in the case of perfect dependence. In this paper, we study the extremal dependence properties of Gaussian scale mixtures and we unify and extend general results on their joint tail decay rates in both asymptotic dependence and independence cases. Motivated by the analysis of spatial extremes, we propose flexible yet parsimonious parametric copula models that smoothly interpolate from asymptotic dependence to independence and include the Gaussian dependence as a special case. We show how these new models can be fitted to high threshold exceedances using a censored likelihood approach, and we demonstrate that they provide valuable information about tail characteristics. In particular, by borrowing strength across locations, our parametric model-based approach can also be used to provide evidence for or against either asymptotic dependence class, hence complementing information given at an exploratory stage by the widely used nonparametric or parametric estimates of the χ and χ̄ coefficients. We demonstrate the capacity of our methodology by adequately capturing the extremal properties of wind speed data collected in the Pacific Northwest, US.

Bridging asymptotic independence and dependence in spatial exbtremes using Gaussian scale mixtures

KAUST Repository

Huser, Raphaë l; Opitz, Thomas; Thibaud, Emeric

2017-01-01

Gaussian scale mixtures are constructed as Gaussian processes with a random variance. They have non-Gaussian marginals and can exhibit asymptotic dependence unlike Gaussian processes, which are asymptotically independent except in the case of perfect dependence. In this paper, we study the extremal dependence properties of Gaussian scale mixtures and we unify and extend general results on their joint tail decay rates in both asymptotic dependence and independence cases. Motivated by the analysis of spatial extremes, we propose flexible yet parsimonious parametric copula models that smoothly interpolate from asymptotic dependence to independence and include the Gaussian dependence as a special case. We show how these new models can be fitted to high threshold exceedances using a censored likelihood approach, and we demonstrate that they provide valuable information about tail characteristics. In particular, by borrowing strength across locations, our parametric model-based approach can also be used to provide evidence for or against either asymptotic dependence class, hence complementing information given at an exploratory stage by the widely used nonparametric or parametric estimates of the χ and χ̄ coefficients. We demonstrate the capacity of our methodology by adequately capturing the extremal properties of wind speed data collected in the Pacific Northwest, US.

Scale-dependent three-dimensional charged black holes in linear and non-linear electrodynamics

Energy Technology Data Exchange (ETDEWEB)

Rincon, Angel; Koch, Benjamin [Pontificia Universidad Catolica de Chile, Instituto de Fisica, Santiago (Chile); Contreras, Ernesto; Bargueno, Pedro; Hernandez-Arboleda, Alejandro [Universidad de los Andes, Departamento de Fisica, Bogota, Distrito Capital (Colombia); Panotopoulos, Grigorios [Universidade de Lisboa, CENTRA, Instituto Superior Tecnico, Lisboa (Portugal)

2017-07-15

In the present work we study the scale dependence at the level of the effective action of charged black holes in Einstein-Maxwell as well as in Einstein-power-Maxwell theories in (2 + 1)-dimensional spacetimes without a cosmological constant. We allow for scale dependence of the gravitational and electromagnetic couplings, and we solve the corresponding generalized field equations imposing the null energy condition. Certain properties, such as horizon structure and thermodynamics, are discussed in detail. (orig.)

On the Soft Limit of the Large Scale Structure Power Spectrum: UV Dependence

CERN Document Server

Garny, Mathias; Porto, Rafael A; Sagunski, Laura

2015-01-01

We derive a non-perturbative equation for the large scale structure power spectrum of long-wavelength modes. Thereby, we use an operator product expansion together with relations between the three-point function and power spectrum in the soft limit. The resulting equation encodes the coupling to ultraviolet (UV) modes in two time-dependent coefficients, which may be obtained from response functions to (anisotropic) parameters, such as spatial curvature, in a modified cosmology. We argue that both depend weakly on fluctuations deep in the UV. As a byproduct, this implies that the renormalized leading order coefficient(s) in the effective field theory (EFT) of large scale structures receive most of their contribution from modes close to the non-linear scale. Consequently, the UV dependence found in explicit computations within standard perturbation theory stems mostly from counter-term(s). We confront a simplified version of our non-perturbative equation against existent numerical simulations, and find good agr...

Burnup dependent core neutronic calculations for research and training reactors via SCALE4.4

International Nuclear Information System (INIS)

Tombakoglu, M.; Cecen, Y.

2001-01-01

In this work, the full core modelling is performed to improve neutronic analyses capability for nuclear research reactors using SCALE4.4 code system. KENOV.a module of SCALE4.4 code system is utilized for full core neutronic analysis. The ORIGEN-S module is coupled with the KENOV.a module to perform burnup dependent neutronic analyses. Results of neutronic calculations for 1 st cycle of Cekmece TR-2 research reactor are presented. In particular, coupling of KENOV.a and ORIGEN-S modules of SCALE4.4 is discussed. The preliminary results of 2-D burnup dependent neutronic calculations are also given. These results are extended to burnup dependent core calculations of TRIGA Mark-II research reactors. The code system developed here is similar to the code system that couples MCNP and ORIGEN2.(author)

Layer-dependent surface potential of phosphorene and anisotropic/layer-dependent charge transfer in phosphorene-gold hybrid systems.

Science.gov (United States)

Xu, Renjing; Yang, Jiong; Zhu, Yi; Yan, Han; Pei, Jiajie; Myint, Ye Win; Zhang, Shuang; Lu, Yuerui

2016-01-07

The surface potential and the efficiency of interfacial charge transfer are extremely important for designing future semiconductor devices based on the emerging two-dimensional (2D) phosphorene. Here, we directly measured the strong layer-dependent surface potential of mono- and few-layered phosphorene on gold, which is consistent with the reported theoretical prediction. At the same time, we used an optical way photoluminescence (PL) spectroscopy to probe charge transfer in the phosphorene-gold hybrid system. We firstly observed highly anisotropic and layer-dependent PL quenching in the phosphorene-gold hybrid system, which is attributed to the highly anisotropic/layer-dependent interfacial charge transfer.

Psychometric testing of the modified Care Dependency Scale (Neuro-CDS).

Science.gov (United States)

Piredda, Michela; Biagioli, Valentina; Gambale, Giulia; Porcelli, Elisa; Barbaranelli, Claudio; Palese, Alvisa; De Marinis, Maria Grazia

2016-01-01

Effective measures of nursing care dependency in neurorehabilitation are warranted to plan nursing interventions to help patients avoid increasing dependency. The Care Dependency Scale (CDS) is a theory-based, comprehensive tool to evaluate functional disability. This study aimed to modify the CDS for neurological and neurorehabilitation patients (Neuro-CDS) and to test its psychometric properties in adult neurorehabilitation inpatients. Exploratory factor analysis (EFA) was performed using a Maximum Likelihood robust (MLR) estimator. The Barthel Index (BI) was used to evaluate concurrent validity. Stability was measured using the Intra-class Correlation Coefficient (ICC). The sample included 124 patients (mean age = 69.7 years, 54% male). The EFA revealed a two-factor structure with good fit indexes, Factor 1 (Physical care dependence) loaded by 11 items and Factor 2 (Psycho-social care dependence) loaded by 4 items. The correlation between factors was 0.61. Correlations between Factor 1 and the BI and between Factor 2 and the BI were r = 0.843 and r = 0.677, respectively (p dependence in neurorehabilitation patients as a basis for individualized and holistic care.

Scale dependence in species turnover reflects variance in species occupancy.

Science.gov (United States)

McGlinn, Daniel J; Hurlbert, Allen H

2012-02-01

Patterns of species turnover may reflect the processes driving community dynamics across scales. While the majority of studies on species turnover have examined pairwise comparison metrics (e.g., the average Jaccard dissimilarity), it has been proposed that the species-area relationship (SAR) also offers insight into patterns of species turnover because these two patterns may be analytically linked. However, these previous links only apply in a special case where turnover is scale invariant, and we demonstrate across three different plant communities that over 90% of the pairwise turnover values are larger than expected based on scale-invariant predictions from the SAR. Furthermore, the degree of scale dependence in turnover was negatively related to the degree of variance in the occupancy frequency distribution (OFD). These findings suggest that species turnover diverges from scale invariance, and as such pairwise turnover and the slope of the SAR are not redundant. Furthermore, models developed to explain the OFD should be linked with those developed to explain species turnover to achieve a more unified understanding of community structure.

Scale dependence of halo and galaxy bias: Effects in real space

International Nuclear Information System (INIS)

Smith, Robert E.; Scoccimarro, Roman; Sheth, Ravi K.

2007-01-01

We examine the scale dependence of dark matter halo and galaxy clustering on very large scales (0.01 -1 ] -1 ] -1 ], and only show amplification on smaller scales, whereas low mass haloes show strong, ∼5%-10%, suppression over the range 0.05 -1 ]<0.15. These results were primarily established through the use of the cross-power spectrum of dark matter and haloes, which circumvents the thorny issue of shot-noise correction. The halo-halo power spectrum, however, is highly sensitive to the shot-noise correction; we show that halo exclusion effects make this sub-Poissonian and a new correction is presented. Our results have special relevance for studies of the baryon acoustic oscillation features in the halo power spectra. Nonlinear mode-mode coupling: (i) damps these features on progressively larger scales as halo mass increases; (ii) produces small shifts in the positions of the peaks and troughs which depend on halo mass. We show that these effects on halo clustering are important over the redshift range relevant to such studies (0< z<2), and so will need to be accounted for when extracting information from precision measurements of galaxy clustering. Our analytic model is described in the language of the ''halo model.'' The halo-halo clustering term is propagated into the nonlinear regime using ''1-loop'' perturbation theory and a nonlinear halo bias model. Galaxies are then inserted into haloes through the halo occupation distribution. We show that, with nonlinear bias parameters derived from simulations, this model produces predictions that are qualitatively in agreement with our numerical results. We then use it to show that the power spectra of red and blue galaxies depend differently on scale, thus underscoring the fact that proper modeling of nonlinear bias parameters will be crucial to derive reliable cosmological constraints. In addition to showing that the bias on very large scales is not simply linear, the model also shows that the halo-halo and halo

Evaluation of the scale dependent dynamic SGS model in the open source code caffa3d.MBRi in wall-bounded flows

Science.gov (United States)

Draper, Martin; Usera, Gabriel

2015-04-01

The Scale Dependent Dynamic Model (SDDM) has been widely validated in large-eddy simulations using pseudo-spectral codes [1][2][3]. The scale dependency, particularly the potential law, has been proved also in a priori studies [4][5]. To the authors' knowledge there have been only few attempts to use the SDDM in finite difference (FD) and finite volume (FV) codes [6][7], finding some improvements with the dynamic procedures (scale independent or scale dependent approach), but not showing the behavior of the scale-dependence parameter when using the SDDM. The aim of the present paper is to evaluate the SDDM in the open source code caffa3d.MBRi, an updated version of the code presented in [8]. caffa3d.MBRi is a FV code, second-order accurate, parallelized with MPI, in which the domain is divided in unstructured blocks of structured grids. To accomplish this, 2 cases are considered: flow between flat plates and flow over a rough surface with the presence of a model wind turbine, taking for this case the experimental data presented in [9]. In both cases the standard Smagorinsky Model (SM), the Scale Independent Dynamic Model (SIDM) and the SDDM are tested. As presented in [6][7] slight improvements are obtained with the SDDM. Nevertheless, the behavior of the scale-dependence parameter supports the generalization of the dynamic procedure proposed in the SDDM, particularly taking into account that no explicit filter is used (the implicit filter is unknown). [1] F. Porté-Agel, C. Meneveau, M.B. Parlange. "A scale-dependent dynamic model for large-eddy simulation: application to a neutral atmospheric boundary layer". Journal of Fluid Mechanics, 2000, 415, 261-284. [2] E. Bou-Zeid, C. Meneveau, M. Parlante. "A scale-dependent Lagrangian dynamic model for large eddy simulation of complex turbulent flows". Physics of Fluids, 2005, 17, 025105 (18p). [3] R. Stoll, F. Porté-Agel. "Dynamic subgrid-scale models for momentum and scalar fluxes in large-eddy simulations of

Temperature dependence in interatomic potentials and an improved potential for Ti

International Nuclear Information System (INIS)

Ackland, G J

2012-01-01

The process of deriving an interatomic potentials represents an attempt to integrate out the electronic degrees of freedom from the full quantum description of a condensed matter system. In practice it is the derivatives of the interatomic potentials which are used in molecular dynamics, as a model for the forces on a system. These forces should be the derivative of the free energy of the electronic system, which includes contributions from the entropy of the electronic states. This free energy is weakly temperature dependent, and although this can be safely neglected in many cases there are some systems where the electronic entropy plays a significant role. Here a method is proposed to incorporate electronic entropy in the Sommerfeld approximation into empirical potentials. The method is applied as a correction to an existing potential for titanium. Thermal properties of the new model are calculated, and a simple method for fixing the melting point and solid-solid phase transition temperature for existing models fitted to zero temperature data is presented.

Path integral solution for some time-dependent potential

International Nuclear Information System (INIS)

Storchak, S.N.

1989-12-01

The quantum-mechanical problem with a time-dependent potential is solved by the path integral method. The solution is obtained by the application of the previously derived general formula for rheonomic homogeneous point transformation and reparametrization in the path integral. (author). 4 refs

Scale-Dependent Habitat Selection and Size-Based Dominance in Adult Male American Alligators.

Directory of Open Access Journals (Sweden)

Bradley A Strickland

Full Text Available Habitat selection is an active behavioral process that may vary across spatial and temporal scales. Animals choose an area of primary utilization (i.e., home range then make decisions focused on resource needs within patches. Dominance may affect the spatial distribution of conspecifics and concomitant habitat selection. Size-dependent social dominance hierarchies have been documented in captive alligators, but evidence is lacking from wild populations. We studied habitat selection for adult male American alligators (Alligator mississippiensis; n = 17 on the Pearl River in central Mississippi, USA, to test whether habitat selection was scale-dependent and individual resource selectivity was a function of conspecific body size. We used K-select analysis to quantify selection at the home range scale and patches within the home range to determine selection congruency and important habitat variables. In addition, we used linear models to determine if body size was related to selection patterns and strengths. Our results indicated habitat selection of adult male alligators was a scale-dependent process. Alligators demonstrated greater overall selection for habitat variables at the patch level and less at the home range level, suggesting resources may not be limited when selecting a home range for animals in our study area. Further, diurnal habitat selection patterns may depend on thermoregulatory needs. There was no relationship between resource selection or home range size and body size, suggesting size-dependent dominance hierarchies may not have influenced alligator resource selection or space use in our sample. Though apparent habitat suitability and low alligator density did not manifest in an observed dominance hierarchy, we hypothesize that a change in either could increase intraspecific interactions, facilitating a dominance hierarchy. Due to the broad and diverse ecological roles of alligators, understanding the factors that influence their

Scale-dependent habitat selection and size-based dominance in adult male American alligators

Science.gov (United States)

Strickland, Bradley A.; Vilella, Francisco; Belant, Jerrold L.

2016-01-01

Habitat selection is an active behavioral process that may vary across spatial and temporal scales. Animals choose an area of primary utilization (i.e., home range) then make decisions focused on resource needs within patches. Dominance may affect the spatial distribution of conspecifics and concomitant habitat selection. Size-dependent social dominance hierarchies have been documented in captive alligators, but evidence is lacking from wild populations. We studied habitat selection for adult male American alligators (Alligator mississippiensis; n = 17) on the Pearl River in central Mississippi, USA, to test whether habitat selection was scale-dependent and individual resource selectivity was a function of conspecific body size. We used K-select analysis to quantify selection at the home range scale and patches within the home range to determine selection congruency and important habitat variables. In addition, we used linear models to determine if body size was related to selection patterns and strengths. Our results indicated habitat selection of adult male alligators was a scale-dependent process. Alligators demonstrated greater overall selection for habitat variables at the patch level and less at the home range level, suggesting resources may not be limited when selecting a home range for animals in our study area. Further, diurnal habitat selection patterns may depend on thermoregulatory needs. There was no relationship between resource selection or home range size and body size, suggesting size-dependent dominance hierarchies may not have influenced alligator resource selection or space use in our sample. Though apparent habitat suitability and low alligator density did not manifest in an observed dominance hierarchy, we hypothesize that a change in either could increase intraspecific interactions, facilitating a dominance hierarchy. Due to the broad and diverse ecological roles of alligators, understanding the factors that influence their social dominance

Spin-dependent potentials from lattice QCD

International Nuclear Information System (INIS)

Koma, Y.

2006-09-01

The spin-dependent corrections to the static inter-quark potential are phenomenologically relevant to describing the fine and hyperfine spin splitting of the heavy quarkonium spectra. We investigate these corrections, which are represented as the field strength correlators on the quark-antiquark source, in SU(3) lattice gauge theory. We use the Polyakov loop correlation function as the quark-antiquark source, and by employing the multi-level algorithm, we obtain remarkably clean signals for these corrections up to intermediate distances of around 0.6 fm. Our observation suggests several new features of the corrections. (orig.)

Multi-scale simulations of droplets in generic time-dependent flows

Science.gov (United States)

Milan, Felix; Biferale, Luca; Sbragaglia, Mauro; Toschi, Federico

2017-11-01

We study the deformation and dynamics of droplets in time-dependent flows using a diffuse interface model for two immiscible fluids. The numerical simulations are at first benchmarked against analytical results of steady droplet deformation, and further extended to the more interesting case of time-dependent flows. The results of these time-dependent numerical simulations are compared against analytical models available in the literature, which assume the droplet shape to be an ellipsoid at all times, with time-dependent major and minor axis. In particular we investigate the time-dependent deformation of a confined droplet in an oscillating Couette flow for the entire capillary range until droplet break-up. In this way these multi component simulations prove to be a useful tool to establish from ``first principles'' the dynamics of droplets in complex flows involving multiple scales. European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 642069. & European Research Council under the European Community's Seventh Framework Program, ERC Grant Agreement No 339032.

Stress- and temperature-dependent scaling behavior of dynamic hysteresis in soft PZT bulk ceramics

International Nuclear Information System (INIS)

Yimnirun, R; Wongsaenmai, S; Wongmaneerung, R; Wongdamnern, N; Ngamjarurojana, A; Ananta, S; Laosiritaworn, Y

2007-01-01

Effects of electric field-frequency, electric field-amplitude, mechanical stress, and temperature on the hysteresis area, especially the scaling form, were investigated in soft lead zirconate titanate (PZT) bulk ceramics. The hysteresis area was found to depend on the frequency and field-amplitude with the same set of exponents as the power-law scaling for both with and without stresses. The inclusion of stresses into the power-law was obtained in the form of σ=0 > ∝ f -0.25 E 0 σ 0.45 which indicates the difference in energy dissipation between the under-stress and stress-free conditions. The power-law temperature scaling relations were obtained for hysteresis area (A) and remanent polarization P r , while the coercivity E C was found to scale linearly with temperature T. The three temperature scaling relations were also field-dependent. At fixed field amplitude E 0 , the scaling relations take the forms of ∝ T -1.1024 , P r ∼T -1.2322 and (E C0 - E C ) ∼T

Plant diversity increases with the strength of negative density dependence at the global scale

Science.gov (United States)

LaManna, Joseph A.; Mangan, Scott A.; Alonso, Alfonso; Bourg, Norman; Brockelman, Warren Y.; Bunyavejchewin, Sarayudh; Chang, Li-Wan; Chiang, Jyh-Min; Chuyong, George B.; Clay, Keith; Condit, Richard; Cordell, Susan; Davies, Stuart J.; Furniss, Tucker J.; Giardina, Christian P.; Gunatilleke, I.A.U. Nimal; Gunatilleke, C.V. Savitri; He, Fangliang; Howe, Robert W.; Hubbell, Stephen P.; Hsieh, Chang-Fu; Inman-Narahari, Faith M.; Janik, David; Johnson, Daniel J.; Kenfack, David; Korte, Lisa; Kral, Kamil; Larson, Andrew J.; Lutz, James A.; McMahon, Sean M.; McShea, William J.; Memiaghe, Herve R.; Nathalang, Anuttara; Novotny, Vojtech; Ong, Perry S.; Orwig, David A.; Ostertag, Rebecca; Parker, Geoffrey G.; Phillips, Richard P.; Sack, Lawren; Sun, I-Fang; Tello, J. Sebastian; Thomas, Duncan W.; Turner, Benjamin L.; Vela Diaz, Dilys M.; Vrska, Tomas; Weiblen, George D.; Wolf, Amy; Yap, Sandra; Myers, Jonathan A.

2017-01-01

Theory predicts that higher biodiversity in the tropics is maintained by specialized interactions among plants and their natural enemies that result in conspecific negative density dependence (CNDD). By using more than 3000 species and nearly 2.4 million trees across 24 forest plots worldwide, we show that global patterns in tree species diversity reflect not only stronger CNDD at tropical versus temperate latitudes but also a latitudinal shift in the relationship between CNDD and species abundance. CNDD was stronger for rare species at tropical versus temperate latitudes, potentially causing the persistence of greater numbers of rare species in the tropics. Our study reveals fundamental differences in the nature of local-scale biotic interactions that contribute to the maintenance of species diversity across temperate and tropical communities.

Potential climatic impacts and reliability of very large-scale wind farms

Directory of Open Access Journals (Sweden)

C. Wang

2010-02-01

Full Text Available Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG emission technologies such as wind energy. The widespread availability of wind power has fueled substantial interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1 °C over land installations. In contrast, surface cooling exceeding 1 °C is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure

Water dependency and water exploitation at global scale as indicators of water security

Science.gov (United States)

De Roo, A. P. J.; Beck, H.; Burek, P.; Bernard, B.

2015-12-01

A water dependency index has been developed indicating the dependency of water consumption from upstream sources of water, sometimes across (multiple) national border. This index is calculated at global scale using the 0.1 global LISFLOOD hydrological modelling system forced by WFDEI meteorological data for the timeframe 1979-2012. The global LISFLOOD model simulates the most important hydrological processes, as well as water abstraction and consumption from various sectors, and flood routing, at daily scale, with sub-timesteps for routing and subgrid parameterization related to elevation and landuse. The model contains also options for water allocation, to allow preferences of water use for particular sectors in water scarce periods. LISFLOOD is also used for the Global Flood Awareness System (GloFAS), the European Flood Awareness System (EFAS), continental scale climate change impact studies on floods and droughts. The water dependency indicator is calculated on a monthly basis, and various annual and multiannual indicators are derived from it. In this study, the indicator will be compared against water security areas known from other studies. Other indicators calculated are the Water Exploitation Index (WEI+), which is a commonly use water security indicator in Europe, and freshwater resources per capita indicators at regional, national and river basin scale. Several climate scnearios are run to indicate future trends in water security.

The length-scale dependence of strain in networks by SANS

CERN Document Server

Pyckhout-Hintzen, W; Heinrich, M; Richter, D; Westermann, S; Straube, E

2002-01-01

We present a SANS study of the length-scale dependence of chain deformation by means of a suitable labeling in dense, cross-linked elastomers of the HDH-type. This length scale is controlled by the size of the label as well as the cross-link density. The results are compared to long homopolymers. The data are analyzed by means of the tube model of topology in rubber elasticity in combination with the random-phase approximation (RPA) to account for interchain correlations. Chain degradation during cross linking is treated by the standard RPA approach for polydisperse multicomponent systems. A transition from locally freely fluctuating to tube-constrained segmental motion was observed. (orig.)

Sarcomere length-dependence of activity-dependent twitch potentiation in mouse skeletal muscle

Directory of Open Access Journals (Sweden)

MacIntosh Brian R

2002-12-01

Full Text Available Abstract Background It has been reported that potentiation of a skeletal muscle twitch response is proportional to muscle length with a negative slope during staircase, and a positive slope during posttetanic potentiation. This study was done to directly compare staircase and posttetanic responses with measurement of sarcomere length to compare their length-dependence. Methods Mouse extensor digitorum longus (EDL muscles were dissected to small bundles of fibers, which permit measurement of sarcomere length (SL, by laser diffraction. In vitro fixed-end contractions of EDL fiber bundles were elicited at 22°C and 35°C at sarcomere lengths ranging from 2.35 μm to 3.85 μm. Twitch contractions were assessed before and after 1.5 s of 75 Hz stimulation at 22°C or during 10 s of 10 Hz stimulation at 22°C or 35°C. Results Staircase potentiation was greater at 35°C than 22°C, and the relative magnitude of the twitch contraction (Pt*/Pt was proportional to sarcomere length with a negative slope, over the range 2.3 μm – 3.7 μm. Linear regression yielded the following: Pt*/Pt = -0.59·SL+3.27 (r2 = 0.74; Pt*/Pt = -0.39·SL+2.34 (r2 = 0.48; and Pt*/Pt = -0.50·SL+2.45 (r2 = 0.80 for staircase at 35°C, and 22°C and posttetanic response respectively. Posttetanic depression rather than potentiation was present at long SL. This indicates that there may be two processes operating in these muscles to modulate the force: one that enhances and a second that depresses the force. Either or both of these processes may have a length-dependence of its mechanism. Conclusion There is no evidence that posttetanic potentiation is fundamentally different from staircase in these muscles.

Size and shape dependent deprotonation potential and proton affinity of nanodiamond

International Nuclear Information System (INIS)

Barnard, Amanda S; Per, Manolo C

2014-01-01

Many important reactions in biology and medicine involve proton abstraction and transfer, and it is integral to applications such as drug delivery. Unlike electrons, which are quantum mechanically delocalized, protons are instantaneously localized on specific residues in these reactions, which can be a distinct advantage. However, the introduction of nanoparticles, such as non-toxic nanodiamonds, to this field complicates matters, as the number of possible sites increases as the inverse radius of the particle. In this paper we present >10 4 simulations that map the size- and shape-dependence of the deprotonation potential and proton affinity of nanodiamonds in the range 1.8–2.7 nm in average diameter. We find that while the average deprotonation potential and proton affinities decrease with size, the site-specific values are inhomogeneous over the surface of the particles, exhibiting strong shape-dependence. The proton affinity is strongly facet-dependent, whereas the deprotonation potential is edge/corner-dependent, which creates a type of spatial hysteresis in the transfer of protons to and from the nanodiamond, and provides new opportunities for selective functionalization. (paper)

Size and shape dependent deprotonation potential and proton affinity of nanodiamond

Science.gov (United States)

Barnard, Amanda S.; Per, Manolo C.

2014-11-01

Many important reactions in biology and medicine involve proton abstraction and transfer, and it is integral to applications such as drug delivery. Unlike electrons, which are quantum mechanically delocalized, protons are instantaneously localized on specific residues in these reactions, which can be a distinct advantage. However, the introduction of nanoparticles, such as non-toxic nanodiamonds, to this field complicates matters, as the number of possible sites increases as the inverse radius of the particle. In this paper we present \\gt {{10}4} simulations that map the size- and shape-dependence of the deprotonation potential and proton affinity of nanodiamonds in the range 1.8-2.7 nm in average diameter. We find that while the average deprotonation potential and proton affinities decrease with size, the site-specific values are inhomogeneous over the surface of the particles, exhibiting strong shape-dependence. The proton affinity is strongly facet-dependent, whereas the deprotonation potential is edge/corner-dependent, which creates a type of spatial hysteresis in the transfer of protons to and from the nanodiamond, and provides new opportunities for selective functionalization.

The three body problem with energy dependent potentials

International Nuclear Information System (INIS)

Kim, Y.E.; McKay, C.M.; McKellar, B.H.J.

1975-10-01

It is shown how to generalize the three body equations of Faddeev, and of Karlsson and Zeiger, to include the case when the two body potential is energy dependent. Such generalizations will prove useful in the three nucleon problem and in three body models of nuclear reactions. (author)

Probing the density dependence of the symmetry potential in intermediate-energy heavy ion collisions

International Nuclear Information System (INIS)

Li Qingfeng; Li Zhuxia; Soff, Sven; Gupta, Raj K; Bleicher, Marcus; Stoecker, Horst

2005-01-01

Based on the ultrarelativistic quantum molecular dynamics model, the effects of the density-dependent symmetry potential for baryons and of the Coulomb potential for produced mesons are investigated for neutron-rich heavy ion collisions at intermediate energies. The calculated results of the Δ - /Δ ++ and π - /π + production ratios show a clear beam-energy dependence on the density-dependent symmetry potential, which is stronger for the π - /π + ratio close to the pion production threshold. The Coulomb potential of the mesons changes the transverse momentum distribution of the π - /π + ratio significantly, though it alters only slightly the π - and π + total yields. The π - yields, especially at midrapidity or at low transverse momenta and the π - /π + ratios at low transverse momenta are shown to be sensitive probes of the density-dependent symmetry potential in dense nuclear matter. The effect of the density-dependent symmetry potential on the production of both K 0 and K + mesons is also investigated

Antipersistent dynamics in short time scale variability of self-potential signals

OpenAIRE

Cuomo, V.; Lanfredi, M.; Lapenna, V.; Macchiato, M.; Ragosta, M.; Telesca, L.

2000-01-01

Time scale properties of self-potential signals are investigated through the analysis of the second order structure function (variogram), a powerful tool to investigate the spatial and temporal variability of observational data. In this work we analyse two sequences of self-potential values measured by means of a geophysical monitoring array located in a seismically active area of Southern Italy. The range of scales investigated goes from a few minutes to several days. It is shown that signal...

Design of Availability-Dependent Distributed Services in Large-Scale Uncooperative Settings

Science.gov (United States)

Morales, Ramses Victor

2009-01-01

Thesis Statement: "Availability-dependent global predicates can be efficiently and scalably realized for a class of distributed services, in spite of specific selfish and colluding behaviors, using local and decentralized protocols". Several types of large-scale distributed systems spanning the Internet have to deal with availability variations…

Redshift space correlations and scale-dependent stochastic biasing of density peaks

Science.gov (United States)

Desjacques, Vincent; Sheth, Ravi K.

2010-01-01

We calculate the redshift space correlation function and the power spectrum of density peaks of a Gaussian random field. Our derivation, which is valid on linear scales k≲0.1hMpc-1, is based on the peak biasing relation given by Desjacques [Phys. Rev. DPRVDAQ1550-7998, 78, 103503 (2008)10.1103/PhysRevD.78.103503]. In linear theory, the redshift space power spectrum is Ppks(k,μ)=exp⁡(-f2σvel2k2μ2)[bpk(k)+bvel(k)fμ2]2Pδ(k), where μ is the angle with respect to the line of sight, σvel is the one-dimensional velocity dispersion, f is the growth rate, and bpk(k) and bvel(k) are k-dependent linear spatial and velocity bias factors. For peaks, the value of σvel depends upon the functional form of bvel. When the k dependence is absent from the square brackets and bvel is set to unity, the resulting expression is assumed to describe models where the bias is linear and deterministic, but the velocities are unbiased. The peak model is remarkable because it has unbiased velocities in this same sense—peak motions are driven by dark matter flows—but, in order to achieve this, bvel must be k dependent. We speculate that this is true in general: k dependence of the spatial bias will lead to k dependence of bvel even if the biased tracers flow with the dark matter. Because of the k dependence of the linear bias parameters, standard manipulations applied to the peak model will lead to k-dependent estimates of the growth factor that could erroneously be interpreted as a signature of modified dark energy or gravity. We use the Fisher formalism to show that the constraint on the growth rate f is degraded by a factor of 2 if one allows for a k-dependent velocity bias of the peak type. Our analysis also demonstrates that the Gaussian smoothing term is part and parcel of linear theory. We discuss a simple estimate of nonlinear evolution and illustrate the effect of the peak bias on the redshift space multipoles. For k≲0.1hMpc-1, the peak bias is deterministic but k

Dependence and physical exercise: Spanish validation of the Exercise Dependence Scale-Revised (EDS-R).

Science.gov (United States)

Sicilia, Alvaro; González-Cutre, David

2011-05-01

The purpose of this study was to validate the Spanish version of the Exercise Dependence Scale-Revised (EDS-R). To achieve this goal, a sample of 531 sport center users was used and the psychometric properties of the EDS-R were examined through different analyses. The results supported both the first-order seven-factor model and the higher-order model (seven first-order factors and one second-order factor). The structure of both models was invariant across age. Correlations among the subscales indicated a related factor model, supporting construct validity of the scale. Alpha values over .70 (except for Reduction in Other Activities) and suitable levels of temporal stability were obtained. Users practicing more than three days per week had higher scores in all subscales than the group practicing with a frequency of three days or fewer. The findings of this study provided reliability and validity for the EDS-R in a Spanish context.

Factorial Validity and Psychometric Examination of the Exercise Dependence Scale-Revised

Science.gov (United States)

Downs, Danielle Symons; Hausenblas, Heather A.; Nigg, Claudio R.

2004-01-01

The research purposes were to examine the factorial and convergent validity, internal consistency, and test-retest reliability of the Exercise Dependence Scale (EDS). Two separate studies, containing a total of 1,263 college students, were undertaken to accomplish these purposes. Participants completed the EDS and measures of exercise behavior and…

Seed harvesting by a generalist consumer is context-dependent: Interactive effects across multiple spatial scales

Science.gov (United States)

Ostoja, Steven M.; Schupp, Eugene W.; Klinger, Rob

2013-01-01

Granivore foraging decisions affect consumer success and determine the quantity and spatial pattern of seed survival. These decisions are influenced by environmental variation at spatial scales ranging from landscapes to local foraging patches. In a field experiment, the effects of seed patch variation across three spatial scales on seed removal by western harvester ants Pogonomyrmex occidentalis were evaluated. At the largest scale we assessed harvesting in different plant communities, at the intermediate scale we assessed harvesting at different distances from ant mounds, and at the smallest scale we assessed the effects of interactions among seed species in local seed neighborhoods on seed harvesting (i.e. resource–consumer interface). Selected seed species were presented alone (monospecific treatment) and in mixture with Bromus tectorum (cheatgrass; mixture treatment) at four distances from P. occidentalis mounds in adjacent intact sagebrush and non-native cheatgrass-dominated communities in the Great Basin, Utah, USA. Seed species differed in harvest, with B. tectorum being least preferred. Large and intermediate scale variation influenced harvest. More seeds were harvested in sagebrush than in cheatgrass-dominated communities (largest scale), and the quantity of seed harvested varied with distance from mounds (intermediate-scale), although the form of the distance effect differed between plant communities. At the smallest scale, seed neighborhood affected harvest, but the patterns differed among seed species considered. Ants harvested fewer seeds from mixed-seed neighborhoods than from monospecific neighborhoods, suggesting context dependence and potential associational resistance. Further, the effects of plant community and distance from mound on seed harvest in mixtures differed from their effects in monospecific treatments. Beyond the local seed neighborhood, selection of seed resources is better understood by simultaneously evaluating removal at

ION-SCALE TURBULENCE IN THE INNER HELIOSPHERE: RADIAL DEPENDENCE

Energy Technology Data Exchange (ETDEWEB)

Comisel, H.; Motschmann, U.; Büchner, J.; Narita, Y.; Nariyuki, Y. [University of Toyama, Faculty of Human Development, 3190, Gofuku, Toyama, 930-8555 (Japan)

2015-10-20

The evolution of the ion-scale plasma turbulence in the inner heliosphere is studied by associating the plasma parameters for hybrid-code turbulence simulations to the radial distance from the Sun via a Solar wind model based mapping procedure. Using a mapping based on a one-dimensional solar wind expansion model, the resulting ion-kinetic scale turbulence is related to the solar wind distance from the Sun. For this purpose the mapping is carried out for various values of ion beta that correspond to the heliocentric distance. It is shown that the relevant normal modes such as ion cyclotron and ion Bernstein modes will occur first at radial distances of about 0.2–0.3 AU, i.e., near the Mercury orbit. This finding can be used as a reference, a prediction to guide the in situ measurements to be performed by the upcoming Solar Orbiter and Solar Probe Plus missions. Furthermore, a radial dependence of the wave-vector anisotropy was obtained. For astrophysical objects this means that the spatial scales of filamentary structures in interstellar media or astrophysical jets can be predicted for photometric observations.

An Integrated Assessment of Location-Dependent Scaling for Microalgae Biofuel Production Facilities

Energy Technology Data Exchange (ETDEWEB)

Coleman, Andre M.; Abodeely, Jared; Skaggs, Richard; Moeglein, William AM; Newby, Deborah T.; Venteris, Erik R.; Wigmosta, Mark S.

2014-06-19

Successful development of a large-scale microalgae-based biofuels industry requires comprehensive analysis and understanding of the feedstock supply chain—from facility siting/design through processing/upgrading of the feedstock to a fuel product. The evolution from pilot-scale production facilities to energy-scale operations presents many multi-disciplinary challenges, including a sustainable supply of water and nutrients, operational and infrastructure logistics, and economic competitiveness with petroleum-based fuels. These challenges are addressed in part by applying the Integrated Assessment Framework (IAF)—an integrated multi-scale modeling, analysis, and data management suite—to address key issues in developing and operating an open-pond facility by analyzing how variability and uncertainty in space and time affect algal feedstock production rates, and determining the site-specific “optimum” facility scale to minimize capital and operational expenses. This approach explicitly and systematically assesses the interdependence of biofuel production potential, associated resource requirements, and production system design trade-offs. The IAF was applied to a set of sites previously identified as having the potential to cumulatively produce 5 billion-gallons/year in the southeastern U.S. and results indicate costs can be reduced by selecting the most effective processing technology pathway and scaling downstream processing capabilities to fit site-specific growing conditions, available resources, and algal strains.

On the soft limit of the large scale structure power spectrum. UV dependence

International Nuclear Information System (INIS)

Garny, Mathias

2015-08-01

We derive a non-perturbative equation for the large scale structure power spectrum of long-wavelength modes. Thereby, we use an operator product expansion together with relations between the three-point function and power spectrum in the soft limit. The resulting equation encodes the coupling to ultraviolet (UV) modes in two time-dependent coefficients, which may be obtained from response functions to (anisotropic) parameters, such as spatial curvature, in a modified cosmology. We argue that both depend weakly on fluctuations deep in the UV. As a byproduct, this implies that the renormalized leading order coefficient(s) in the effective field theory (EFT) of large scale structures receive most of their contribution from modes close to the non-linear scale. Consequently, the UV dependence found in explicit computations within standard perturbation theory stems mostly from counter-term(s). We confront a simplified version of our non-perturbative equation against existent numerical simulations, and find good agreement within the expected uncertainties. Our approach can in principle be used to precisely infer the relevance of the leading order EFT coefficient(s) using small volume simulations in an 'anisotropic separate universe' framework. Our results suggest that the importance of these coefficient(s) is a ∝ 10% effect, and plausibly smaller.

Accurate calibration of the velocity-dependent one-scale model for domain walls

International Nuclear Information System (INIS)

Leite, A.M.M.; Martins, C.J.A.P.; Shellard, E.P.S.

2013-01-01

We study the asymptotic scaling properties of standard domain wall networks in several cosmological epochs. We carry out the largest field theory simulations achieved to date, with simulation boxes of size 2048 3 , and confirm that a scale-invariant evolution of the network is indeed the attractor solution. The simulations are also used to obtain an accurate calibration for the velocity-dependent one-scale model for domain walls: we numerically determine the two free model parameters to have the values c w =0.34±0.16 and k w =0.98±0.07, which are of higher precision than (but in agreement with) earlier estimates.

Accurate calibration of the velocity-dependent one-scale model for domain walls

Energy Technology Data Exchange (ETDEWEB)

Leite, A.M.M., E-mail: up080322016@alunos.fc.up.pt [Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Ecole Polytechnique, 91128 Palaiseau Cedex (France); Martins, C.J.A.P., E-mail: Carlos.Martins@astro.up.pt [Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Shellard, E.P.S., E-mail: E.P.S.Shellard@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

2013-01-08

We study the asymptotic scaling properties of standard domain wall networks in several cosmological epochs. We carry out the largest field theory simulations achieved to date, with simulation boxes of size 2048{sup 3}, and confirm that a scale-invariant evolution of the network is indeed the attractor solution. The simulations are also used to obtain an accurate calibration for the velocity-dependent one-scale model for domain walls: we numerically determine the two free model parameters to have the values c{sub w}=0.34{+-}0.16 and k{sub w}=0.98{+-}0.07, which are of higher precision than (but in agreement with) earlier estimates.

Linking the influence and dependence of people on biodiversity across scales.

Science.gov (United States)

Isbell, Forest; Gonzalez, Andrew; Loreau, Michel; Cowles, Jane; Díaz, Sandra; Hector, Andy; Mace, Georgina M; Wardle, David A; O'Connor, Mary I; Duffy, J Emmett; Turnbull, Lindsay A; Thompson, Patrick L; Larigauderie, Anne

2017-05-31

Biodiversity enhances many of nature's benefits to people, including the regulation of climate and the production of wood in forests, livestock forage in grasslands and fish in aquatic ecosystems. Yet people are now driving the sixth mass extinction event in Earth's history. Human dependence and influence on biodiversity have mainly been studied separately and at contrasting scales of space and time, but new multiscale knowledge is beginning to link these relationships. Biodiversity loss substantially diminishes several ecosystem services by altering ecosystem functioning and stability, especially at the large temporal and spatial scales that are most relevant for policy and conservation.

Spatial data analysis and integration for regional-scale geothermal potential mapping, West Java, Indonesia

Energy Technology Data Exchange (ETDEWEB)

Carranza, Emmanuel John M.; Barritt, Sally D. [Department of Earth Systems Analysis, International Institute for Geo-information Science and Earth Observation (ITC), Enschede (Netherlands); Wibowo, Hendro; Sumintadireja, Prihadi [Laboratory of Volcanology and Geothermal, Geology Department, Institute of Technology Bandung (ITB), Bandung (Indonesia)

2008-06-15

Conceptual modeling and predictive mapping of potential for geothermal resources at the regional-scale in West Java are supported by analysis of the spatial distribution of geothermal prospects and thermal springs, and their spatial associations with geologic features derived from publicly available regional-scale spatial data sets. Fry analysis shows that geothermal occurrences have regional-scale spatial distributions that are related to Quaternary volcanic centers and shallow earthquake epicenters. Spatial frequency distribution analysis shows that geothermal occurrences have strong positive spatial associations with Quaternary volcanic centers, Quaternary volcanic rocks, quasi-gravity lows, and NE-, NNW-, WNW-trending faults. These geological features, with their strong positive spatial associations with geothermal occurrences, constitute spatial recognition criteria of regional-scale geothermal potential in a study area. Application of data-driven evidential belief functions in GIS-based predictive mapping of regional-scale geothermal potential resulted in delineation of high potential zones occupying 25% of West Java, which is a substantial reduction of the search area for further exploration of geothermal resources. The predicted high potential zones delineate about 53-58% of the training geothermal areas and 94% of the validated geothermal occurrences. The results of this study demonstrate the value of regional-scale geothermal potential mapping in: (a) data-poor situations, such as West Java, and (b) regions with geotectonic environments similar to the study area. (author)

Density-scaling exponents and virial potential-energy correlation ...

Indian Academy of Sciences (India)

This paper investigates the relation between the density-scaling exponent γ and the virial potential energy correlation coefficient R at several thermodynamic state points in three dimensions for the generalized (2n, n) Lennard-Jones (LJ) system for n = 4, 9, 12, 18, as well as for the standard n = 6 LJ system in two,three, and ...

Scale-dependent climatic drivers of human epidemics in ancient China

Czech Academy of Sciences Publication Activity Database

Tian, H.; Yan, Ch.; Xu, L.; Büntgen, Ulf; Stenseth, N. C.; Zhang, Z.

2017-01-01

Roč. 114, č. 49 (2017), s. 12970-12975 ISSN 0027-8424 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : infectious-diseases * northern-hemisphere * cholera dynamics * time-series * 2 millennia * reconstruction * variability * management * plague * ad * epidemics * climate * scale dependent * natural disaster * disease Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 9.661, year: 2016

The Harmonic Potential Theorem for a Quantum System with Time-Dependent Effective Mass

International Nuclear Information System (INIS)

Lai Meng-Yun; Xiao Duan-Liang; Pan Xiao-Yin

2015-01-01

We investigate the many-body wave function of a quantum system with time-dependent effective mass, confined by a harmonic potential with time-dependent frequency, and perturbed by a time-dependent spatially homogeneous electric field. It is found that the wave function is comprised of a phase factor times the solution to the unperturbed time-dependent Schrödinger equation with the latter being translated by a time-dependent value that satisfies the classical driven equation of motion. The wave function reduces to that of the harmonic potential theorem wave function when both the effective mass and frequency are static. An example of application is also given. (paper)

Small-scale fuel cell cogen: application potentials and market strategies

International Nuclear Information System (INIS)

Vogel, Bernd

2000-01-01

Small (less than 5 kW) fuel-cell cogeneration systems are now being developed for use in residential buildings. The devices are expected to be on the market in five years. The article discusses the potential for their large-scale introduction, the impact of this new technology on the natural gas business, potential applications and marketing strategies

Effects of momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei

International Nuclear Information System (INIS)

Li Baoan; Das, Champak B.; Das Gupta, Subal; Gale, Charles

2004-01-01

Using an isospin- and momentum-dependent transport model we study effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy E sym (ρ) lead to significantly different predictions on several E sym (ρ)-sensitive experimental observables especially for energetic nucleons. The momentum- and density-dependence of the symmetry potential have to be determined simultaneously in order to extract the E sym (ρ) accurately. The isospin asymmetry of midrapidity nucleons at high transverse momenta is particularly sensitive to the momentum-dependence of the symmetry potential. It is thus very useful for investigating accurately the equation of state of dense neutron-rich matter

An efficient and accurate method to obtain the energy-dependent Green function for general potentials

International Nuclear Information System (INIS)

Kramer, T; Heller, E J; Parrott, R E

2008-01-01

Time-dependent quantum mechanics provides an intuitive picture of particle propagation in external fields. Semiclassical methods link the classical trajectories of particles with their quantum mechanical propagation. Many analytical results and a variety of numerical methods have been developed to solve the time-dependent Schroedinger equation. The time-dependent methods work for nearly arbitrarily shaped potentials, including sources and sinks via complex-valued potentials. Many quantities are measured at fixed energy, which is seemingly not well suited for a time-dependent formulation. Very few methods exist to obtain the energy-dependent Green function for complicated potentials without resorting to ensemble averages or using certain lead-in arrangements. Here, we demonstrate in detail a time-dependent approach, which can accurately and effectively construct the energy-dependent Green function for very general potentials. The applications of the method are numerous, including chemical, mesoscopic, and atomic physics

Monte Carlo determination of the spin-dependent potentials

International Nuclear Information System (INIS)

Campostrini, M.; Moriarty, K.J.M.; Rebbi, C.

1987-05-01

Calculation of the bound states of heavy quark systems by a Hamiltonian formulation based on an expansion of the interaction into inverse powers of the quark mass is discussed. The potentials for the spin-orbit and spin-spin coupling between quark and antiquark, which are responsible for the fine and hyperfine splittings in heavy quark spectroscopy, are expressed as expectation values of Wilson loop factors with suitable insertions of chromomagnetic or chromoelectric fields. A Monte Carlo simulation has been used to evaluate the expectation values and, from them, the spin-dependent potentials. The Monte Carlo calculation is reported to show a long-range, non-perturbative component in the interaction

Scale dependent drivers of wild bee diversity in tropical heterogeneous agricultural landscapes.

Science.gov (United States)

Basu, Parthiba; Parui, Arpan Kumar; Chatterjee, Soumik; Dutta, Aditi; Chakraborty, Pushan; Roberts, Stuart; Smith, Barbara

2016-10-01

Factors associated with agricultural intensification, for example, loss of seminatural vegetation and pesticide use has been shown to adversely affect the bee community. These factors may impact the bee community differently at different landscape scales. The scale dependency is expected to be more pronounced in heterogeneous landscapes. However, the scale-dependent response of the bee community to drivers of its decline is relatively understudied, especially in the tropics where the agricultural landscape is often heterogeneous. This study looked at effects of agricultural intensification on bee diversity at patch and landscape scales in a tropical agricultural landscape. Wild bees were sampled using 12 permanent pan trap stations. Patch and landscape characteristics were measured within a 100 m (patch scale) and a 500 m (landscape scale) radius of pan trap stations. Information on pesticide input was obtained from farmer surveys. Data on vegetation cover, productivity, and percentage of agricultural and fallow land (FL) were collected using satellite imagery. Intensive areas in a bee-site network were less specialized in terms of resources to attract rare bee species while the less intensive areas, which supported more rare species, were more vulnerable to disturbance. A combination of patch quality and diversity as well as pesticide use regulates species diversity at the landscape scale (500 m), whereas pesticide quantity drove diversity at the patch scale (100 m). At the landscape scale, specialization of each site in terms of resources for bees increased with increasing patch diversity and FL while at the patch scale specialization declined with increased pesticide use. Bee functional groups responded differentially to landscape characteristics as well as pesticide use. Wood nesting bees were negatively affected by the number of pesticides used but other bee functional groups were not sensitive to pesticides. Synthesis and Applications : Different factors

Exponential potentials, scaling solutions and inflation

International Nuclear Information System (INIS)

Wands, D.; Copeland, E.J.; Liddle, A.R.

1993-01-01

The goal of driving a period of rapid inflation in the early universe in a model motivated by grand unified theories has been given new life in recent years in the context of extended gravity theories. Extended inflation is one model based on a Brans-Dicke type gravity which can allow a very general first-order phase transition to complete by changing the expansion of the false vacuum dominated universe from an exponential to a power law expansion. This inflation is conformally equivalent to general relativity where the vacuum energy density is exponentially dependent upon a dilaton field. With this in mind, the authors consider in this paper the evolution of a scalar field σ with a potential V(σ) = V 0 exp(-λκ 1/2 σ) in a spatially flat (κ = 0) Friedmann-Robertson-Walker metric in the presence of a barotropic (P = (γ - 1)ρ) fluid. Here κ = 8πG, and λ is a dimensionless constant describing the steepness of the potential. It is well known that if the potential is sufficiently flat (λ small), the energy density of the scalar field dominated and the universe undergoes power law inflation. The behavior of fields with a steep potential seems to be less well known, although the results the authors present here are not new. 11 refs., 2 figs

Scale Dependence of Female Ungulate Reproductive Success in Relation to Nutritional Condition, Resource Selection and Multi-Predator Avoidance.

Directory of Open Access Journals (Sweden)

Jared F Duquette

Full Text Available Female ungulate reproductive success is dependent on the survival of their young, and affected by maternal resource selection, predator avoidance, and nutritional condition. However, potential hierarchical effects of these factors on reproductive success are largely unknown, especially in multi-predator landscapes. We expanded on previous research of neonatal white-tailed deer (Odocoileus virginianus daily survival within home ranges to assess if resource use, integrated risk of 4 mammalian predators, maternal nutrition, winter severity, hiding cover, or interactions among these variables best explained landscape scale variation in daily or seasonal survival during the post-partum period. We hypothesized that reproductive success would be limited greater by predation risk at coarser spatiotemporal scales, but habitat use at finer scales. An additive model of daily non-ideal resource use and maternal nutrition explained the most (69% variation in survival; though 65% of this variation was related to maternal nutrition. Strong support of maternal nutrition across spatiotemporal scales did not fully support our hypothesis, but suggested reproductive success was related to dam behaviors directed at increasing nutritional condition. These behaviors were especially important following severe winters, when dams produced smaller fawns with less probability of survival. To increase nutritional condition and decrease wolf (Canis lupus predation risk, dams appeared to place fawns in isolated deciduous forest patches near roads. However, this resource selection represented non-ideal resources for fawns, which had greater predation risk that led to additive mortalities beyond those related to resources alone. Although the reproductive strategy of dams resulted in greater predation of fawns from alternative predators, it likely improved the life-long reproductive success of dams, as many were late-aged (>10 years old and could have produced multiple litters

A multi scale approximation solution for the time dependent Boltzmann-transport equation

International Nuclear Information System (INIS)

Merk, B.

2004-03-01

The basis of all transient simulations for nuclear reactor cores is the reliable calculation of the power production. The local power distribution is generally calculated by solving the space, time, energy and angle dependent neutron transport equation known as Boltzmann equation. The computation of exact solutions of the Boltzmann equation is very time consuming. For practical numerical simulations approximated solutions are usually unavoidable. The objective of this work is development of an effective multi scale approximation solution for the Boltzmann equation. Most of the existing methods are based on separation of space and time. The new suggested method is performed without space-time separation. This effective approximation solution is developed on the basis of an expansion for the time derivative of different approximations to the Boltzmann equation. The method of multiple scale expansion is used for the expansion of the time derivative, because the problem of the stiff time behaviour can't be expressed by standard expansion methods. This multiple scale expansion is used in this work to develop approximation solutions for different approximations of the Boltzmann equation, starting from the expansion of the point kinetics equations. The resulting analytic functions are used for testing the applicability and accuracy of the multiple scale expansion method for an approximation solution with 2 delayed neutron groups. The results are tested versus the exact analytical results for the point kinetics equations. Very good agreement between both solutions is obtained. The validity of the solution with 2 delayed neutron groups to approximate the behaviour of the system with 6 delayed neutron groups is demonstrated in an additional analysis. A strategy for a solution with 4 delayed neutron groups is described. A multiple scale expansion is performed for the space-time dependent diffusion equation for one homogenized cell with 2 delayed neutron groups. The result is

Experimental study of parametric dependence of electron-scale turbulence in a spherical tokamak

Energy Technology Data Exchange (ETDEWEB)

Ren, Y.; Guttenfelder, W.; Kaye, S. M.; Mazzucato, E.; Bell, R. E.; Diallo, A.; LeBlanc, B. P. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Domier, C. W.; Lee, K. C. [University of California at Davis, Davis, California 95616 (United States); Smith, D. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Yuh, H. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)

2012-05-15

Electron-scale turbulence is predicted to drive anomalous electron thermal transport. However, experimental study of its relation with transport is still in its early stage. On the National Spherical Tokamak Experiment (NSTX), electron-scale density fluctuations are studied with a novel tangential microwave scattering system with high radial resolution of {+-}2 cm. Here, we report a study of parametric dependence of electron-scale turbulence in NSTX H-mode plasmas. The dependence on density gradient is studied through the observation of a large density gradient variation in the core induced by an edge localized mode (ELM) event, where we found the first clear experimental evidence of density gradient stabilization of electron-gyro scale turbulence in a fusion plasma. This observation, coupled with linear gyro-kinetic calculations, leads to the identification of the observed instability as toroidal electron temperature gradient (ETG) modes. It is observed that longer wavelength ETG modes, k{sub Up-Tack }{rho}{sub s} Less-Than-Or-Equivalent-To 10 ({rho}{sub s} is the ion gyroradius at electron temperature and k{sub Up-Tack} is the wavenumber perpendicular to local equilibrium magnetic field), are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in electron thermal diffusivity. Comparisons with nonlinear ETG gyrokinetic simulations show ETG turbulence may be able to explain the experimental electron heat flux observed before the ELM event. The collisionality dependence of electron-scale turbulence is also studied by systematically varying plasma current and toroidal field, so that electron gyroradius ({rho}{sub e}), electron beta ({beta}{sub e}), and safety factor (q{sub 95}) are kept approximately constant. More than a factor of two change in electron collisionality, {nu}{sub e}{sup *}, was achieved, and we found that the spectral power of electron-scale turbulence appears to increase as {nu}{sub e}{sup *} is

Alignment between Satellite and Central Galaxies in the SDSS DR7: Dependence on Large-scale Environment

Science.gov (United States)

Wang, Peng; Luo, Yu; Kang, Xi; Libeskind, Noam I.; Wang, Lei; Zhang, Youcai; Tempel, Elmo; Guo, Quan

2018-06-01

The alignment between satellites and central galaxies has been studied in detail both in observational and theoretical works. The widely accepted fact is that satellites preferentially reside along the major axis of their central galaxy. However, the origin and large-scale environmental dependence of this alignment are still unknown. In an attempt to determine these variables, we use data constructed from Sloan Digital Sky Survey DR7 to investigate the large-scale environmental dependence of this alignment with emphasis on examining the alignment’s dependence on the color of the central galaxy. We find a very strong large-scale environmental dependence of the satellite–central alignment (SCA) in groups with blue centrals. Satellites of blue centrals in knots are preferentially located perpendicular to the major axes of the centrals, and the alignment angle decreases with environment, namely, when going from knots to voids. The alignment angle strongly depends on the {}0.1(g-r) color of centrals. We suggest that the SCA is the result of a competition between satellite accretion within large-scale structure (LSS) and galaxy evolution inside host halos. For groups containing red central galaxies, the SCA is mainly determined by the evolution effect, while for blue central dominated groups, the effect of the LSS plays a more important role, especially in knots. Our results provide an explanation for how the SCA forms within different large-scale environments. The perpendicular case in groups and knots with blue centrals may also provide insight into understanding similar polar arrangements, such as the formation of the Milky Way and Centaurus A’s satellite system.

Morphology Dependent Flow Stress in Nickel-Based Superalloys in the Multi-Scale Crystal Plasticity Framework

Directory of Open Access Journals (Sweden)

Shahriyar Keshavarz

2017-11-01

Full Text Available This paper develops a framework to obtain the flow stress of nickel-based superalloys as a function of γ-γ’ morphology. The yield strength is a major factor in the design of these alloys. This work provides additional effects of γ’ morphology in the design scope that has been adopted for the model developed by authors. In general, the two-phase γ-γ’ morphology in nickel-based superalloys can be divided into three variables including γ’ shape, γ’ volume fraction and γ’ size in the sub-grain microstructure. In order to obtain the flow stress, non-Schmid crystal plasticity constitutive models at two length scales are employed and bridged through a homogenized multi-scale framework. The multi-scale framework includes two sub-grain and homogenized grain scales. For the sub-grain scale, a size-dependent, dislocation-density-based finite element model (FEM of the representative volume element (RVE with explicit depiction of the γ-γ’ morphology is developed as a building block for the homogenization. For the next scale, an activation-energy-based crystal plasticity model is developed for the homogenized single crystal of Ni-based superalloys. The constitutive models address the thermo-mechanical behavior of nickel-based superalloys for a large temperature range and include orientation dependencies and tension-compression asymmetry. This homogenized model is used to obtain the morphology dependence on the flow stress in nickel-based superalloys and can significantly expedite crystal plasticity FE simulations in polycrystalline microstructures, as well as higher scale FE models in order to cast and design superalloys.

Linking the influence and dependence of people on biodiversity across scales

Science.gov (United States)

Isbell, Forest; Gonzalez, Andrew; Loreau, Michel; Cowles, Jane; Díaz, Sandra; Hector, Andy; Mace, Georgina M.; Wardle, David A.; O’Connor, Mary I.; Duffy, J. Emmett; Turnbull, Lindsay A.; Thompson, Patrick L.; Larigauderie, Anne

2017-01-01

Biodiversity enhances many of nature’s benefits to people, including the regulation of climate and the production of wood in forests, livestock forage in grasslands and fish in aquatic ecosystems. Yet people are now driving the sixth mass extinction event in Earth’s history. Human dependence and influence on biodiversity have mainly been studied separately and at contrasting scales of space and time, but new multiscale knowledge is beginning to link these relationships. Biodiversity loss substantially diminishes several ecosystem services by altering ecosystem functioning and stability, especially at the large temporal and spatial scales that are most relevant for policy and conservation. PMID:28569811

Scale dependence of the halo bias in general local-type non-Gaussian models I: analytical predictions and consistency relations

International Nuclear Information System (INIS)

Nishimichi, Takahiro

2012-01-01

The large-scale clustering pattern of biased tracers is known to be a powerful probe of the non-Gaussianities in the primordial fluctuations. The so-called scale-dependent bias has been reported in various type of models of primordial non-Gaussianities. We focus on local-type non-Gaussianities, and unify the derivations in the literature of the scale-dependent bias in the presence of multiple Gaussian source fields as well as higher-order coupling to cover the models described by frequently-discussed f NL , g NL and t NL parameterization. We find that the resultant power spectrum is characterized by two parameters responsible for the shape and the amplitude of the scale-dependent bias in addition to the Gaussian bias factor. We show how (a generalized version of) Suyama-Yamaguchi inequality between f NL and t NL can directly be accessible from the observed power spectrum through the dependence on our new parameter which controls the shape of the scale-dependent bias. The other parameter for the amplitude of the scale-dependent bias is shown to be useful to distinguish the simplest quadratic non-Gaussianities (i.e., f NL -type) from higher-order ones (g NL and higher), if one measures it from multiple species of galaxies or clusters of galaxies. We discuss the validity and limitations of our analytic results by comparison with numerical simulations in an accompanying paper

Challenges in Upscaling Geomorphic Transport Laws: Scale-dependence of Local vs. Non-local Formalisms and Derivation of Closures (Invited)

Science.gov (United States)

Foufoula-Georgiou, E.; Ganti, V. K.; Passalacqua, P.

2010-12-01

Nonlinear geomorphic transport laws are often derived from mechanistic considerations at a point, and yet they are implemented on 90m or 30 m DEMs, presenting a mismatch in the scales of derivation and application of the flux laws. Since estimates of local slopes and curvatures are known to depend on the scale of the DEM used in their computation, two questions arise: (1) how to meaningfully compensate for the scale dependence, if any, of local transport laws? and (2) how to formally derive, via upscaling, constitutive laws that are applicable at larger scales? Recently, non-local geomorphic transport laws for sediment transport on hillslopes have been introduced using the concept of an integral flux that depends on topographic attributes in the vicinity of a point of interest. In this paper, we demonstrate the scale dependence of local nonlinear hillslope sediment transport laws and derive a closure term via upscaling (Reynolds averaging). We also show that the non-local hillslope transport laws are inherently scale independent owing to their non-local, scale-free nature. These concepts are demonstrated via an application to a small subbasin of the Oregon Coast Range using 2m LiDAR topographic data.

Effect of deformation and orientation on spin orbit density dependent nuclear potential

Science.gov (United States)

Mittal, Rajni; Kumar, Raj; Sharma, Manoj K.

2017-11-01

Role of deformation and orientation is investigated on spin-orbit density dependent part VJ of nuclear potential (VN=VP+VJ) obtained within semi-classical Thomas Fermi approach of Skyrme energy density formalism. Calculations are performed for 24-54Si+30Si reactions, with spherical target 30Si and projectiles 24-54Si having prolate and oblate shapes. The quadrupole deformation β2 is varying within range of 0.023 ≤ β2 ≤0.531 for prolate and -0.242 ≤ β2 ≤ -0.592 for oblate projectiles. The spin-orbit dependent potential gets influenced significantly with inclusion of deformation and orientation effect. The spin-orbit barrier and position gets significantly influenced by both the sign and magnitude of β2-deformation. Si-nuclei with β220. The possible role of spin-orbit potential on barrier characteristics such as barrier height, barrier curvature and on the fusion pocket is also probed. In reference to prolate and oblate systems, the angular dependence of spin-orbit potential is further studied on fusion cross-sections.

Assessment of renewable energy resources potential for large scale and standalone applications in Ethiopia

NARCIS (Netherlands)

Tucho, Gudina Terefe; Weesie, Peter D.M.; Nonhebel, Sanderine

2014-01-01

This study aims to determine the contribution of renewable energy to large scale and standalone application in Ethiopia. The assessment starts by determining the present energy system and the available potentials. Subsequently, the contribution of the available potentials for large scale and

Geo-Ontologies Are Scale Dependent

Science.gov (United States)

Frank, A. U.

2009-04-01

Philosophers aim at a single ontology that describes "how the world is"; for information systems we aim only at ontologies that describe a conceptualization of reality (Guarino 1995; Gruber 2005). A conceptualization of the world implies a spatial and temporal scale: what are the phenomena, the objects and the speed of their change? Few articles (Reitsma et al. 2003) seem to address that an ontology is scale specific (but many articles indicate that ontologies are scale-free in another sense namely that they are scale free in the link densities between concepts). The scale in the conceptualization can be linked to the observation process. The extent of the support of the physical observation instrument and the sampling theorem indicate what level of detail we find in a dataset. These rules apply for remote sensing or sensor networks alike. An ontology of observations must include scale or level of detail, and concepts derived from observations should carry this relation forward. A simple example: in high resolution remote sensing image agricultural plots and roads between them are shown, at lower resolution, only the plots and not the roads are visible. This gives two ontologies, one with plots and roads, the other with plots only. Note that a neighborhood relation in the two different ontologies also yield different results. References Gruber, T. (2005). "TagOntology - a way to agree on the semantics of tagging data." Retrieved October 29, 2005., from http://tomgruber.org/writing/tagontology-tagcapm-talk.pdf. Guarino, N. (1995). "Formal Ontology, Conceptual Analysis and Knowledge Representation." International Journal of Human and Computer Studies. Special Issue on Formal Ontology, Conceptual Analysis and Knowledge Representation, edited by N. Guarino and R. Poli 43(5/6). Reitsma, F. and T. Bittner (2003). Process, Hierarchy, and Scale. Spatial Information Theory. Cognitive and Computational Foundations of Geographic Information ScienceInternational Conference

Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows

International Nuclear Information System (INIS)

Zhang, Lei; Du, Yun; Zuo, Guang-Hua; Gao, Yuan; Yong, Gao-Chan

2012-01-01

In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, the effect of the momentum dependence of nuclear symmetry potential on nuclear transverse and elliptic flows in the neutron-rich reaction 132 Sn+ 124 Sn at a beam energy of 400MeV/nucleon is studied. We find that the momentum dependence of nuclear symmetry potential affects the rapidity distribution of the free neutron to proton ratio, the neutron and the proton transverse flows as a function of rapidity. The momentum dependence of nuclear symmetry potential affects the neutron-proton differential transverse flow more evidently than the difference of neutron and proton transverse flows as well as the difference of proton and neutron elliptic flows. It is thus better to probe the symmetry energy by using the difference of neutron and proton flows since the momentum dependence of nuclear symmetry potential is still an open question. And it is better to probe the momentum dependence of nuclear symmetry potential by using the neutron-proton differential transverse flow the rapidity distribution of the free neutron to proton ratio. (orig.)

Plasma screening effects on the energies of hydrogen atom under the influence of velocity-dependent potential

International Nuclear Information System (INIS)

Bahar, M. K.

2014-01-01

In order to examine the plasma screening and velocity-dependent potential effects on the hydrogen atom, the Schrödinger equation including a more general exponential cosine screened Coulomb and velocity-dependent potential is solved numerically in the framework asymptotic iteration method. The more general exponential cosine screened Coulomb potential is used to model Debye and quantum plasma for the specific values of the parameters in its structure. However, in order to examine effects of velocity-dependent potential on energy values of hydrogen atom in Debye and quantum plasma, the isotropic form factor of velocity-dependent potential is given as harmonic oscillator type, ρ(r)=ρ o r 2 . Then, the energies of s and p states are calculated numerically without any approximation. In order to investigate thoroughly plasma screening effects and contribution of velocity-dependent potential on energy values of hydrogen atom, the corresponding calculations are carried out by using different values of parameters of more general exponential cosine screened Coulomb potential and isotropic dependence, results of which are discussed

Latent trait standardization of the benzodiazepine dependence self-report questionnaire using the Rasch scaling model.

NARCIS (Netherlands)

Kan, C.C.; Ven, A.H.G.S. van der; Breteler, M.H.M.; Zitman, F.G.

2001-01-01

The aim of the present study was to obtain standardized scores that correspond with the raw scores on the four Rasch scales of the Benzodiazepine Dependence-Self Report Questionnaire (Bendep-SRQ). The eligible normative group for standardization of the Bendep-SRQ scales consisted of 217 general

Latent Trait Standardization of the Benzodiazepine Dependence Self-Report Questionnaire using the Rasch Scaling Model

NARCIS (Netherlands)

Kan, C.C.; Ven, A.H.G.S. van der; Breteler, M.H.M.; Zitman, F.G.

2001-01-01

The aim of the present study was to obtain standardized scores that correspond with the raw scores on the four Rasch scales of the Benzodiazepine Dependence-Self Report Questionnaire (Bendep-SRQ). The eligible normative group for standardization of the Bendep-SRQ scales consisted of 217 general

Is the permeability of naturally fractured rocks scale dependent?

Science.gov (United States)

Azizmohammadi, Siroos; Matthäi, Stephan K.

2017-09-01

The equivalent permeability, keq of stratified fractured porous rocks and its anisotropy is important for hydrocarbon reservoir engineering, groundwater hydrology, and subsurface contaminant transport. However, it is difficult to constrain this tensor property as it is strongly influenced by infrequent large fractures. Boreholes miss them and their directional sampling bias affects the collected geostatistical data. Samples taken at any scale smaller than that of interest truncate distributions and this bias leads to an incorrect characterization and property upscaling. To better understand this sampling problem, we have investigated a collection of outcrop-data-based Discrete Fracture and Matrix (DFM) models with mechanically constrained fracture aperture distributions, trying to establish a useful Representative Elementary Volume (REV). Finite-element analysis and flow-based upscaling have been used to determine keq eigenvalues and anisotropy. While our results indicate a convergence toward a scale-invariant keq REV with increasing sample size, keq magnitude can have multi-modal distributions. REV size relates to the length of dilated fracture segments as opposed to overall fracture length. Tensor orientation and degree of anisotropy also converge with sample size. However, the REV for keq anisotropy is larger than that for keq magnitude. Across scales, tensor orientation varies spatially, reflecting inhomogeneity of the fracture patterns. Inhomogeneity is particularly pronounced where the ambient stress selectively activates late- as opposed to early (through-going) fractures. While we cannot detect any increase of keq with sample size as postulated in some earlier studies, our results highlight a strong keq anisotropy that influences scale dependence.

Scale dependence of effective media properties

International Nuclear Information System (INIS)

Tidwell, V.C.; VonDoemming, J.D.; Martinez, K.

1992-01-01

For problems where media properties are measured at one scale and applied at another, scaling laws or models must be used in order to define effective properties at the scale of interest. The accuracy of such models will play a critical role in predicting flow and transport through the Yucca Mountain Test Site given the sensitivity of these calculations to the input property fields. Therefore, a research programhas been established to gain a fundamental understanding of how properties scale with the aim of developing and testing models that describe scaling behavior in a quantitative-manner. Scaling of constitutive rock properties is investigated through physical experimentation involving the collection of suites of gas permeability data measured over a range of discrete scales. Also, various physical characteristics of property heterogeneity and the means by which the heterogeneity is measured and described are systematically investigated to evaluate their influence on scaling behavior. This paper summarizes the approach that isbeing taken toward this goal and presents the results of a scoping study that was conducted to evaluate the feasibility of the proposed research

Optimized effective potential in real time: Problems and prospects in time-dependent density-functional theory

International Nuclear Information System (INIS)

Mundt, Michael; Kuemmel, Stephan

2006-01-01

The integral equation for the time-dependent optimized effective potential (TDOEP) in time-dependent density-functional theory is transformed into a set of partial-differential equations. These equations only involve occupied Kohn-Sham orbitals and orbital shifts resulting from the difference between the exchange-correlation potential and the orbital-dependent potential. Due to the success of an analog scheme in the static case, a scheme that propagates orbitals and orbital shifts in real time is a natural candidate for an exact solution of the TDOEP equation. We investigate the numerical stability of such a scheme. An approximation beyond the Krieger-Li-Iafrate approximation for the time-dependent exchange-correlation potential is analyzed

The evolution of streams in a time-dependent potential

NARCIS (Netherlands)

Buist, Hans J. T.; Helmi, Amina

2015-01-01

We study the evolution of streams in a time-dependent spherical gravitational potential. Our goal is to establish what are the imprints of this time evolution on the properties of streams as well as their observability. To this end, we have performed a suite of test-particle experiments for a host

Scale dependence of the diversity–stability relationship in a temperate grassland

Science.gov (United States)

Zhang, Yunhai; He, Nianpeng; Loreau, Michel; Pan, Qingmin; Han, Xingguo

2018-01-01

A positive relationship between biodiversity and ecosystem stability has been reported in many ecosystems; however, it has yet to be determined whether and how spatial scale affects this relationship. Here, for the first time, we assessed the effects of alpha, beta and gamma diversity on ecosystem stability and the scale dependence of the slope of the diversity–stability relationship.By employing a long-term (33 years) dataset from a temperate grassland, northern China, we calculated the all possible spatial scales with the complete combination from the basic 1-m2 plots.Species richness was positively associated with ecosystem stability through species asynchrony and overyielding at all spatial scales (1, 2, 3, 4 and 5 m2). Both alpha and beta diversity were positively associated with gamma stability.Moreover, the slope of the diversity–area relationship was significantly higher than that of the stability–area relationship, resulting in a decline of the slope of the diversity–stability relationship with increasing area.Synthesis. With the positive species diversity effect on ecosystem stability from small to large spatial scales, our findings demonstrate the need to maintain a high biodiversity and biotic heterogeneity as insurance against the risks incurred by ecosystems in the face of global environmental changes. PMID:29725139

Scale dependence of the diversity-stability relationship in a temperate grassland.

Science.gov (United States)

Zhang, Yunhai; He, Nianpeng; Loreau, Michel; Pan, Qingmin; Han, Xingguo

2018-05-01

A positive relationship between biodiversity and ecosystem stability has been reported in many ecosystems; however, it has yet to be determined whether and how spatial scale affects this relationship. Here, for the first time, we assessed the effects of alpha, beta and gamma diversity on ecosystem stability and the scale dependence of the slope of the diversity-stability relationship.By employing a long-term (33 years) dataset from a temperate grassland, northern China, we calculated the all possible spatial scales with the complete combination from the basic 1-m 2 plots.Species richness was positively associated with ecosystem stability through species asynchrony and overyielding at all spatial scales (1, 2, 3, 4 and 5 m 2 ). Both alpha and beta diversity were positively associated with gamma stability.Moreover, the slope of the diversity-area relationship was significantly higher than that of the stability-area relationship, resulting in a decline of the slope of the diversity-stability relationship with increasing area. Synthesis. With the positive species diversity effect on ecosystem stability from small to large spatial scales, our findings demonstrate the need to maintain a high biodiversity and biotic heterogeneity as insurance against the risks incurred by ecosystems in the face of global environmental changes.

Energy dependence of a local equivalent potential for RGM phase shifts for 16O + 16O

International Nuclear Information System (INIS)

Ait-Tahar, S.; Mackintosh, R.S.; Cooper, S.G.; Wada, T.

1993-01-01

We have found, using the IP inversion method, the local representation of a potential that in S(l) equivalent to the RGM nonlocal potential of Wada and Horiuchi. Phase shifts corresponding to RGM calculations at laboratory energies 30, 41, 49, 59, 150, 350 and 500 MeV were inverted and the resulting local potentials compared with the local (but l-dependent) potentials obtained previously in the WKB-RGM scheme. The present l-independent potentials exhibit a smooth radial variation and show marked differences from previous results. The energy dependence arises from that of the exchange term and from the conversion of the l-dependence into an additional energy dependence. In particular, we show that the energy dependence of the volume integrals in this energy region is different from earlier WKB-RGM predictions. (orig.)

Organism traits determine the strength of scale-dependent bio-geomorphic feedbacks: a flume study on three intertidal plant species

NARCIS (Netherlands)

Bouma, T.J.; Temmerman, S.; van Duren, L.A.; Martini, E.; Vandenbruwaene, W.; Callaghan, D.P.; Balke, T.; Biermans, G.; Klaassen, P.C.; van Steeg, R.; Dekker, F.; van de Koppel, J.; de Vries, Mindert; Herman, P.M.J.

2013-01-01

There is a growing recognition of the important role of scale-dependent feedback for biogeomorphological landscape formation, where organisms locally improve survival and growth but at the same time negatively affect organisms at larger distance. However, little is known on how scale-dependent

Organism traits determine the strength of scale-dependent bio-geomorphic feedbacks: A flume study on three intertidal plant species

NARCIS (Netherlands)

Bouma, T.J.; Temmerman, S.; van Duren, L.A.; Martini, E.; Vandenbruwaene, W.; Callaghan, D.P.; Balke, T.; Biermans, G.; Klaassen, P.C.; van Steeg, R.; Dekker, F.; van de Koppel, J.; Herman, P.M.J.; de Vries, M.B.

2013-01-01

There is a growing recognition of the important role of scale-dependent feedback for biogeomorphological landscape formation, where organisms locally improve survival and growth but at the same time negatively affect organisms at larger distance. However, little is known on how scale-dependent

Quantum models with energy-dependent potentials solvable in terms of exceptional orthogonal polynomials

International Nuclear Information System (INIS)

Schulze-Halberg, Axel; Roy, Pinaki

2017-01-01

We construct energy-dependent potentials for which the Schrödinger equations admit solutions in terms of exceptional orthogonal polynomials. Our method of construction is based on certain point transformations, applied to the equations of exceptional Hermite, Jacobi and Laguerre polynomials. We present several examples of boundary-value problems with energy-dependent potentials that admit a discrete spectrum and the corresponding normalizable solutions in closed form.

Quantum models with energy-dependent potentials solvable in terms of exceptional orthogonal polynomials

Energy Technology Data Exchange (ETDEWEB)

Schulze-Halberg, Axel, E-mail: axgeschu@iun.edu [Department of Mathematics and Actuarial Science, Indiana University Northwest, 3400 Broadway, Gary IN 46408 (United States); Department of Physics, Indiana University Northwest, 3400 Broadway, Gary IN 46408 (United States); Roy, Pinaki, E-mail: pinaki@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India)

2017-03-15

We construct energy-dependent potentials for which the Schrödinger equations admit solutions in terms of exceptional orthogonal polynomials. Our method of construction is based on certain point transformations, applied to the equations of exceptional Hermite, Jacobi and Laguerre polynomials. We present several examples of boundary-value problems with energy-dependent potentials that admit a discrete spectrum and the corresponding normalizable solutions in closed form.

Interaural Level Difference Dependent Gain Control and Synaptic Scaling Underlying Binaural Computation

Science.gov (United States)

Xiong, Xiaorui R.; Liang, Feixue; Li, Haifu; Mesik, Lukas; Zhang, Ke K.; Polley, Daniel B.; Tao, Huizhong W.; Xiao, Zhongju; Zhang, Li I.

2013-01-01

Binaural integration in the central nucleus of inferior colliculus (ICC) plays a critical role in sound localization. However, its arithmetic nature and underlying synaptic mechanisms remain unclear. Here, we showed in mouse ICC neurons that the contralateral dominance is created by a “push-pull”-like mechanism, with contralaterally dominant excitation and more bilaterally balanced inhibition. Importantly, binaural spiking response is generated apparently from an ipsilaterally-mediated scaling of contralateral response, leaving frequency tuning unchanged. This scaling effect is attributed to a divisive attenuation of contralaterally-evoked synaptic excitation onto ICC neurons with their inhibition largely unaffected. Thus, a gain control mediates the linear transformation from monaural to binaural spike responses. The gain value is modulated by interaural level difference (ILD) primarily through scaling excitation to different levels. The ILD-dependent synaptic scaling and gain adjustment allow ICC neurons to dynamically encode interaural sound localization cues while maintaining an invariant representation of other independent sound attributes. PMID:23972599

Psychometric examination and factorial validity of the Exercise Dependence Scale-Revised in Italian exercisers.

Science.gov (United States)

Costa, Sebastiano; Cuzzocrea, Francesca; Hausenblas, Heather A; Larcan, Rosalba; Oliva, Patrizia

2012-12-01

Background and aims The purpose of this study was to verify the factorial structure, internal validity, reliability, and criterion validity of the 21-item Exercise Dependence Scale-Revised (EDS-R) in an Italian sample. Methods Italian voluntary (N = 519) users of gyms who had a history of regular exercise for over a year completed the EDS-R and measures of exercise frequency. Results and conclusions Confirmatory factor analyses demonstrated a good fit to the hypothesized 7-factor model, and adequate internal consistency for the scale was evidenced. Criterion validity was evidenced by significant correlations among all the subscale of the EDS and exercise frequency. Finally, individuals at risk for exercise dependence reported more exercise behavior compared to the nondependent-symptomatic and nondependent-asymptomatic groups. These results suggest that the seven subscales of the Italian version of the EDS are measuring the construct of exercise dependence as defined by the DSM-IV criteria for substance dependence and also confirm previous research using the EDS-R in other languages. More research is needed to examine the psychometric properties of the EDS-R in diverse populations with various research designs.

Energy-dependent microscopic optical potential for scattering of nucleons on light nuclei

Energy Technology Data Exchange (ETDEWEB)

Farag, M.Y.H.; Esmael, E.H. [Cairo University, Physics Department, Faculty of Science, Giza (Egypt); Maridi, H.M. [Cairo University, Physics Department, Faculty of Science, Giza (Egypt); Taiz University, Physics Department, Faculty of Applied Science, Taiz (Yemen)

2014-06-15

We present an energy-dependent microscopic optical model potential for elastic scattering of nucleons on light nuclei. The single-folding model is used for the real part of the optical potential (OP), while the imaginary part is derived within the high-energy approximation theory. The energy dependence of the OP is determined from the parameterization of the volume integrals those calculated from the best-fit OP that fit the experimental data of the cross sections and analyzing powers. This energy-dependent OP is successfully applied to analyze the proton elastic scattering of {sup 4,6,i8}He, {sup 6,7}Li, and {sup 9,10}Be nuclei at low and intermediate incident energies up to 200MeV/nucleon. (orig.)

The dispersal of contaminants in heterogeneous aquifers: a review of methods of estimating scale dependent parameters

International Nuclear Information System (INIS)

Farmer, C.L.

1986-02-01

The design and assessment of underground waste disposal options requires modelling the dispersal of contaminants within aquifers. The logical structure of the development and application of disposal models is discussed. In particular we examine the validity and interpretation of the gradient diffusion model. The effective dispersion parameters in such a model seem to depend upon the scale on which they are measured. This phenomenon is analysed and methods for modelling scale dependent parameters are reviewed. Specific recommendations regarding the modelling of contaminant dispersal are provided. (author)

Further application of angular momentum dependent potentials to proton elastic scattering

International Nuclear Information System (INIS)

Kobos, A.M.; Mackintosh, R.S.

1981-01-01

We extend our application of the iota-dependent model to a wider range of cases. We include more non-closed shell nuclei and some heavy nuclei as targets, getting better fits than previously found, with no substantial exceptions to the systematic properties of the iota-dependent potential. For one mass sequence we find shell effects, but note that the results would be more certain if more analysing powers data were available. A simple pattern of iota-dependence is a universal feature of proton scattering between 20 and 60 MeV. Since the effect on (p,p') is large the effect of iota-dependence on direct reactions should not be ignored. (author)

Spanish adaptation of the NDSS (Nicotine Dependence Syndrome Scale) and assessment of nicotine-dependent individuals at primary care health centers in Spain.

Science.gov (United States)

Becoña, Elisardo; López, Ana; Fernández del Río, Elena; Míguez, Ma Carmen; Castro, Josefina

2010-11-01

The availability of adequate instruments for the assessment of nicotine dependence is an important factor that is relevant in the area of tobacco addiction. In this study, we present a Spanish validation of the Nicotine Dependence Syndrome Scale (NDSS) (Shiffman, Waters, & Hickcox, 2004). The sample was composed ofpatients, all daily smokers, who visited their General Practitioner (GP) at five Primary Health Care Centers in different cities of Spain (N = 637). The results indicated adequate reliability for the general factor that assesses nicotine dependence (NDSS-Total) (Cronbach's alpha = .76). Factor analysis confirms the five factors of the original validation: Drive, Continuity, Stereotypy, Priority, and Tolerance. It must be noted that reliability is adequate for the first, and moderate or low for the rest. The NDSS-T and its scales correlate significantly with the Fagerström Test for Nicotine Dependence (FTND), with the nicotine dependence criteria of the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) as assessed through the Structured Clinical Interview for DSM-IV (SCID), with carbon monoxide levels in expired air (CO), and with the number of cigarettes smoked. The ROC curve indicates that the NDSS-T has a score of .79 which is under the curve (.69 for the FTND), thus the prediction of nicotine dependence is adequate. We conclude that this instrument is useful (in terms of its total score NDSS-T) for assessing nicotine dependence for Spanish smokers (in Spain), as has been found in other countries, language groups, and cultures.

Quantum gravity fluctuations flatten the Planck-scale Higgs potential

Science.gov (United States)

Eichhorn, Astrid; Hamada, Yuta; Lumma, Johannes; Yamada, Masatoshi

2018-04-01

We investigate asymptotic safety of a toy model of a singlet-scalar extension of the Higgs sector including two real scalar fields under the impact of quantum-gravity fluctuations. Employing functional renormalization group techniques, we search for fixed points of the system which provide a tentative ultraviolet completion of the system. We find that in a particular regime of the gravitational parameter space the canonically marginal and relevant couplings in the scalar sector—including the mass parameters—become irrelevant at the ultraviolet fixed point. The infrared potential for the two scalars that can be reached from that fixed point is fully predicted and features no free parameters. In the remainder of the gravitational parameter space, the values of the quartic couplings in our model are predicted. In light of these results, we discuss whether the singlet-scalar could be a dark-matter candidate. Furthermore, we highlight how "classical scale invariance" in the sense of a flat potential of the scalar sector at the Planck scale could arise as a consequence of asymptotic safety.

State and location dependence of action potential metabolic cost in cortical pyramidal neurons.

Science.gov (United States)

Hallermann, Stefan; de Kock, Christiaan P J; Stuart, Greg J; Kole, Maarten H P

2012-06-03

Action potential generation and conduction requires large quantities of energy to restore Na(+) and K(+) ion gradients. We investigated the subcellular location and voltage dependence of this metabolic cost in rat neocortical pyramidal neurons. Using Na(+)/K(+) charge overlap as a measure of action potential energy efficiency, we found that action potential initiation in the axon initial segment (AIS) and forward propagation into the axon were energetically inefficient, depending on the resting membrane potential. In contrast, action potential backpropagation into dendrites was efficient. Computer simulations predicted that, although the AIS and nodes of Ranvier had the highest metabolic cost per membrane area, action potential backpropagation into the dendrites and forward propagation into axon collaterals dominated energy consumption in cortical pyramidal neurons. Finally, we found that the high metabolic cost of action potential initiation and propagation down the axon is a trade-off between energy minimization and maximization of the conduction reliability of high-frequency action potentials.

Potential dependence of surface crystal structure of iron passive films in borate buffer solution

International Nuclear Information System (INIS)

Deng, Huihua; Nanjo, Hiroshi; Qian, Pu; Santosa, Arifin; Ishikawa, Ikuo; Kurata, Yoshiaki

2007-01-01

The effect of passivation potential on surface crystal structure, apparent thickness and passivity of oxide films formed on pure iron prepared by plasma sputter deposition was investigated. The crystallinity was improved with passivation potential and the width of atomically flat terraces was expanded to 6 nm when passivating at 750 mV for 15 min, as observed by ex situ scanning tunneling microscopy (STM) after aging in air (<30% RH). Apparent thickness and passivity are linearly dependent on passivation potential. The former weakly depends on passivation duration, the latter strongly depends on passivation duration. This is well explained by the correlation between crystal structure and passivity

Exact wavefunctions for a time-dependent Coulomb potential

International Nuclear Information System (INIS)

Menouar, S; Maamache, M; Saadi, Y; Choi, J R

2008-01-01

The one-dimensional Schroedinger equation associated with a time-dependent Coulomb potential is studied. The invariant operator method (Lewis and Riesenfeld) and unitary transformation approach are employed to derive quantum solutions of the system. We obtain an ordinary second-order differential equation whose analytical exact solution has been unknown. It is confirmed that the form of this equation is similar to the radial Schroedinger equation for the hydrogen atom in a (arbitrary) strong magnetic field. The qualitative properties for the eigenstates spectrum are described separately for the different values of the parameter ω 0 appearing in the x 2 term, x being the position, i.e., ω 0 > 0, ω 0 0 = 0. For the ω 0 = 0 case, the eigenvalue equation of invariant operator reduces to a solvable form and, consequently, we have provided exact eigenstates of the time-dependent Hamiltonian system

The flattening of the average potential in models with fermions

International Nuclear Information System (INIS)

Bornholdt, S.

1993-01-01

The average potential is a scale dependent scalar effective potential. In a phase with spontaneous symmetry breaking its inner region becomes flat as the averaging extends over infinite volume and the average potential approaches the convex effective potential. Fermion fluctuations affect the shape of the average potential in this region and its flattening with decreasing physical scale. They have to be taken into account to find the true minimum of the scalar potential which determines the scale of spontaneous symmetry breaking. (orig.)

Length-Scale-Dependent Phase Transformation of LiFePO4 : An In situ and Operando Study Using Micro-Raman Spectroscopy and XRD.

Science.gov (United States)

Siddique, N A; Salehi, Amir; Wei, Zi; Liu, Dong; Sajjad, Syed D; Liu, Fuqiang

2015-08-03

The charge and discharge of lithium ion batteries are often accompanied by electrochemically driven phase-transformation processes. In this work, two in situ and operando methods, that is, micro-Raman spectroscopy and X-ray diffraction (XRD), have been combined to study the phase-transformation process in LiFePO4 at two distinct length scales, namely, particle-level scale (∼1 μm) and macroscopic scale (∼several cm). In situ Raman studies revealed a discrete mode of phase transformation at the particle level. Besides, the preferred electrochemical transport network, particularly the carbon content, was found to govern the sequence of phase transformation among particles. In contrast, at the macroscopic level, studies conducted at four different discharge rates showed a continuous but delayed phase transformation. These findings uncovered the intricate phase transformation in LiFePO4 and potentially offer valuable insights into optimizing the length-scale-dependent properties of battery materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extended consolidation of scaling laws of potentials covering over the representative tandem-mirror operations in GAMMA 10

International Nuclear Information System (INIS)

Cho, T.; Higaki, H.; Hirata, M.

2003-01-01

Scaling laws of potential formation and associated effects are constructed in the GAMMA 10 tandem mirror. A novel proposal of extended consolidation and generalization of the two major theories of (i) Cohen's strong electron cyclotron heating (ECH) theory for the formation physics of plasma confining potentials, and (ii) the generalized Pastukhov theory for the effectiveness of the produced potentials on plasma confinement is made through the use of the energy-balance equation. This proposal is then followed by the verification from experimental data in two representative operational modes, characterized in terms of (i) a high-potential mode having kV-order plasma-confining potentials, and (ii) a hot-ion mode yielding fusion neutrons with 10-20 keV bulk-ion temperatures. The importance of the validity of the proposed consolidated physics-based scaling is highlighted by a possibility of extended capability inherent in Pastukhov's prediction of requiring ion-confining potential (φ c ) of 30 kV for a fusion Q value of unity on the basis of an application of Cohen's potential formation method. In addition to the above potential physics scaling, an externally controllable parameter scaling including both plug and barrier ECH powers for potential formation is investigated. The combination of (i) the physics scaling of the above-proposed consolidation over potential formation and effects with (ii) the externally controllable practical ECH power scaling provides a scalable way for the future tandem-mirror researches. Under the assumption of the validity of the extension of the present theoretically well interpreted scaling, the formation of Pastukhov's predicted φ c for confining Q=1 plasmas is scaled to require total plug with barrier ECH powers of 3 MW. (author)

Scaling in soft spheres: fragility invariance on the repulsive potential softness

International Nuclear Information System (INIS)

Michele, Cristiano De; Sciortino, Francesco; Coniglio, Antonio

2004-01-01

We address the question of the dependence of the fragility of glass forming supercooled liquids on the 'softness' of an interacting potential by performing numerical simulation of a binary mixture of soft spheres with different power n of the interparticle repulsive potential. We show that the temperature dependence of the diffusion coefficients for various n collapses onto a universal curve, supporting the unexpected view that fragility is not related to the hard core repulsion. We also find that the configurational entropy correlates with the slowing down of the dynamics for all studied n. (letter to the editor)

Fluorescence quenching studies of potential-dependent DNA reorientation dynamics at glassy carbon electrode surfaces.

Science.gov (United States)

Li, Qin; Cui, Chenchen; Higgins, Daniel A; Li, Jun

2012-09-05

The potential-dependent reorientation dynamics of double-stranded DNA (ds-DNA) attached to planar glassy carbon electrode (GCE) surfaces were investigated. The orientation state of surface-bound ds-DNA was followed by monitoring the fluorescence from a 6-carboxyfluorescein (FAM6) fluorophore covalently linked to the distal end of the DNA. Positive potentials (i.e., +0.2 V vs open circuit potential, OCP) caused the ds-DNA to align parallel to the electrode surface, resulting in strong dipole-electrode quenching of FAM6 fluorescence. Switching of the GCE potential to negative values (i.e., -0.2 V vs OCP) caused the ds-DNA to reorient perpendicular to the electrode surface, with a concomitant increase in FAM6 fluorescence. In addition to the very fast (submilliseconds) dynamics of the initial reorientation process, slow (0.1-0.9 s) relaxation of FAM6 fluorescence to intermediate levels was also observed after potential switching. These dynamics have not been previously described in the literature. They are too slow to be explained by double layer charging, and chronoamperometry data showed no evidence of such effects. Both the amplitude and rate of the dynamics were found to depend upon buffer concentration, and ds-DNA length, demonstrating a dependence on the double layer field. The dynamics are concluded to arise from previously undetected complexities in the mechanism of potential-dependent ds-DNA reorientation. The possible origins of these dynamics are discussed. A better understanding of these dynamics will lead to improved models for potential-dependent ds-DNA reorientation at electrode surfaces and will facilitate the development of advanced electrochemical devices for detection of target DNAs.

Wave packet dynamics and photofragmentation in time-dependent quadratic potentials

DEFF Research Database (Denmark)

Møller, Klaus Braagaard; Henriksen, Niels Engholm

1996-01-01

We study the dynamics of generalized harmonic oscillator states in time-dependent quadratic potentials and derive analytical expressions for the momentum space and the Wigner phase space representation of these wave packets. Using these results we consider a model for the rotational excitation...

Semiclassical approximations for a momentum dependent one-body potential

International Nuclear Information System (INIS)

Dworzecka, M.; Moszkowski, S.A.

1976-08-01

Recently a semiclassical approximation was applied by Jennings, et al., for a system of noninteracting fermions in a local one-body potential. This is a way to calculate shell corrections alternative to Strutinsky's method. This method was generalized to a spherical but a momentum dependent potential of the form, V(r) + 1 / 2 (p 2 W(r) + W(r)p 2 ). Explicit expressions are developed for the number of particles and the smooth sum of single particle energies in terms of the Fermi energy and the one-body potential and its first two derivatives. They are calculated for selected values of the parameters and compared with the sum of single particle energies obtained by numerical solution of the Schroedinger equation. The difference between the two is evidently the shell correction

Incorporating cold-air pooling into downscaled climate models increases potential refugia for snow-dependent species within the Sierra Nevada Ecoregion, CA.

Directory of Open Access Journals (Sweden)

Jennifer A Curtis

Full Text Available We present a unique water-balance approach for modeling snowpack under historic, current and future climates throughout the Sierra Nevada Ecoregion. Our methodology uses a finer scale (270 m than previous regional studies and incorporates cold-air pooling, an atmospheric process that sustains cooler temperatures in topographic depressions thereby mitigating snowmelt. Our results are intended to support management and conservation of snow-dependent species, which requires characterization of suitable habitat under current and future climates. We use the wolverine (Gulo gulo as an example species and investigate potential habitat based on the depth and extent of spring snowpack within four National Park units with proposed wolverine reintroduction programs. Our estimates of change in spring snowpack conditions under current and future climates are consistent with recent studies that generally predict declining snowpack. However, model development at a finer scale and incorporation of cold-air pooling increased the persistence of April 1st snowpack. More specifically, incorporation of cold-air pooling into future climate projections increased April 1st snowpack by 6.5% when spatially averaged over the study region and the trajectory of declining April 1st snowpack reverses at mid-elevations where snow pack losses are mitigated by topographic shading and cold-air pooling. Under future climates with sustained or increased precipitation, our results indicate a high likelihood for the persistence of late spring snowpack at elevations above approximately 2,800 m and identify potential climate refugia sites for snow-dependent species at mid-elevations, where significant topographic shading and cold-air pooling potential exist.

Scale Dependence of Dark Energy Antigravity

Science.gov (United States)

Perivolaropoulos, L.

2002-09-01

We investigate the effects of negative pressure induced by dark energy (cosmological constant or quintessence) on the dynamics at various astrophysical scales. Negative pressure induces a repulsive term (antigravity) in Newton's law which dominates on large scales. Assuming a value of the cosmological constant consistent with the recent SnIa data we determine the critical scale $r_c$ beyond which antigravity dominates the dynamics ($r_c \\sim 1Mpc $) and discuss some of the dynamical effects implied. We show that dynamically induced mass estimates on the scale of the Local Group and beyond are significantly modified due to negative pressure. We also briefly discuss possible dynamical tests (eg effects on local Hubble flow) that can be applied on relatively small scales (a few $Mpc$) to determine the density and equation of state of dark energy.

The Climate Potentials and Side-Effects of Large-Scale terrestrial CO2 Removal - Insights from Quantitative Model Assessments

Science.gov (United States)

Boysen, L.; Heck, V.; Lucht, W.; Gerten, D.

2015-12-01

Terrestrial carbon dioxide removal (tCDR) through dedicated biomass plantations is considered as one climate engineering (CE) option if implemented at large-scale. While the risks and costs are supposed to be small, the effectiveness depends strongly on spatial and temporal scales of implementation. Based on simulations with a dynamic global vegetation model (LPJmL) we comprehensively assess the effectiveness, biogeochemical side-effects and tradeoffs from an earth system-analytic perspective. We analyzed systematic land-use scenarios in which all, 25%, or 10% of natural and/or agricultural areas are converted to tCDR plantations including the assumption that biomass plantations are established once the 2°C target is crossed in a business-as-usual climate change trajectory. The resulting tCDR potentials in year 2100 include the net accumulated annual biomass harvests and changes in all land carbon pools. We find that only the most spatially excessive, and thus undesirable, scenario would be capable to restore the 2° target by 2100 under continuing high emissions (with a cooling of 3.02°C). Large-scale biomass plantations covering areas between 1.1 - 4.2 Gha would produce a climate reduction potential of 0.8 - 1.4°C. tCDR plantations at smaller scales do not build up enough biomass over this considered period and the potentials to achieve global warming reductions are substantially lowered to no more than 0.5-0.6°C. Finally, we demonstrate that the (non-economic) costs for the Earth system include negative impacts on the water cycle and on ecosystems, which are already under pressure due to both land use change and climate change. Overall, tCDR may lead to a further transgression of land- and water-related planetary boundaries while not being able to set back the crossing of the planetary boundary for climate change. tCDR could still be considered in the near-future mitigation portfolio if implemented on small scales on wisely chosen areas.

Feedforward and feedback frequency-dependent interactions in a large-scale laminar network of the primate cortex.

Science.gov (United States)

Mejias, Jorge F; Murray, John D; Kennedy, Henry; Wang, Xiao-Jing

2016-11-01

Interactions between top-down and bottom-up processes in the cerebral cortex hold the key to understanding attentional processes, predictive coding, executive control, and a gamut of other brain functions. However, the underlying circuit mechanism remains poorly understood and represents a major challenge in neuroscience. We approached this problem using a large-scale computational model of the primate cortex constrained by new directed and weighted connectivity data. In our model, the interplay between feedforward and feedback signaling depends on the cortical laminar structure and involves complex dynamics across multiple (intralaminar, interlaminar, interareal, and whole cortex) scales. The model was tested by reproducing, as well as providing insights into, a wide range of neurophysiological findings about frequency-dependent interactions between visual cortical areas, including the observation that feedforward pathways are associated with enhanced gamma (30 to 70 Hz) oscillations, whereas feedback projections selectively modulate alpha/low-beta (8 to 15 Hz) oscillations. Furthermore, the model reproduces a functional hierarchy based on frequency-dependent Granger causality analysis of interareal signaling, as reported in recent monkey and human experiments, and suggests a mechanism for the observed context-dependent hierarchy dynamics. Together, this work highlights the necessity of multiscale approaches and provides a modeling platform for studies of large-scale brain circuit dynamics and functions.

Ambipolar potential formation in TMX

International Nuclear Information System (INIS)

Correl, D.L.; Allen, S.L.; Casper, T.A.

1981-01-01

TMX experimental data on ambipolar potential control and on the accompanying electrostatic confinement are reported. New results on the radial dependence of the central-cell confining potential are given. Radial and axial particle losses as well as scaling of the central-cell axial confinement are discussed

Crystal plasticity based modeling of time and scale dependent behavior of thin films

NARCIS (Netherlands)

Erturk, I.; Gao, K.; Bielen, J.A.; Dommelen, van J.A.W.; Geers, M.G.D.

2013-01-01

The micro and sub-micro scale dimensions of the components of modern high-tech products pose challenging engineering problems that require advanced tools to tackle them. An example hereof is time dependent strain recovery, here referred to as anelasticity, which is observed in metallic thin film

Psychometric Properties of the Persian Version of Care Dependency Scale in Nursing Homes.

Science.gov (United States)

Rajabi, Gholamreza; Namadmalan, Masoume; Dijkstra, Ate; Ghasemzade, Roya; Foroughan, Mahshid; Zahednejad, Shahla

The purpose of the study was to examine the psychometric properties of the Persian version of the Care Dependency Scale (CDS) in nursing homes. Instrument development. The English version of the CDS was translated into Persian. A convenience sample of 140 (100 older people without dementia and 40 patients with dementia) Persian-speaking people were selected from the nursing homes in Ahvaz, Iran. Cronbach's alpha, discriminant validity, and construct validity (exploratory factor analysis) were examined. Exploratory factor analysis indicated that the CDS has two factors, including psychosocial and somatic factors. Discriminant validity showed that the CDS can differentiate patients with dementia from the older adults without dementia. The results of the study showed that the Persian CDS is a reliable and valid scale when used in nursing homes. The Persian version of the CDS can help clinicians and nurses to assess patients' need and the degree of care dependency among older adults in Persian-speaking areas.

Brain state-dependence of electrically evoked potentials monitored with head-mounted electronics.

Science.gov (United States)

Richardson, Andrew G; Fetz, Eberhard E

2012-11-01

Inferring changes in brain connectivity is critical to studies of learning-related plasticity and stimulus-induced conditioning of neural circuits. In addition, monitoring spontaneous fluctuations in connectivity can provide insight into information processing during different brain states. Here, we quantified state-dependent connectivity changes throughout the 24-h sleep-wake cycle in freely behaving monkeys. A novel, head-mounted electronic device was used to electrically stimulate at one site and record evoked potentials at other sites. Electrically evoked potentials (EEPs) revealed the connectivity pattern between several cortical sites and the basal forebrain. We quantified state-dependent changes in the EEPs. Cortico-cortical EEP amplitude increased during slow-wave sleep, compared to wakefulness, while basal-cortical EEP amplitude decreased. The results demonstrate the utility of using portable electronics to document state-dependent connectivity changes in freely behaving primates.

Nanoscale Roughness of Faults Explained by the Scale-Dependent Yield Stress of Geologic Materials

Science.gov (United States)

Thom, C.; Brodsky, E. E.; Carpick, R. W.; Goldsby, D. L.; Pharr, G.; Oliver, W.

2017-12-01

Despite significant differences in their lithologies and slip histories, natural fault surfaces exhibit remarkably similar scale-dependent roughness over lateral length scales spanning 7 orders of magnitude, from microns to tens of meters. Recent work has suggested that a scale-dependent yield stress may result in such a characteristic roughness, but experimental evidence in favor of this hypothesis has been lacking. We employ an atomic force microscope (AFM) operating in intermittent-contact mode to map the topography of the Corona Heights fault surface. Our experiments demonstrate that the Corona Heights fault exhibits isotropic self-affine roughness with a Hurst exponent of 0.75 +/- 0.05 at all wavelengths from 60 nm to 10 μm. If yield stress controls roughness, then the roughness data predict that yield strength varies with length scale as λ-0.25 +/ 0.05. To test the relationship between roughness and yield stress, we conducted nanoindentation tests on the same Corona Heights sample and a sample of the Yair Fault, a carbonate fault surface that has been previously characterized by AFM. A diamond Berkovich indenter tip was used to indent the samples at a nominally constant strain rate (defined as the loading rate divided by the load) of 0.2 s-1. The continuous stiffness method (CSM) was used to measure the indentation hardness (which is proportional to yield stress) and the elastic modulus of the sample as a function of depth in each test. For both samples, the yield stress decreases with increasing size of the indents, a behavior consistent with that observed for many engineering materials and recently for other geologic materials such as olivine. The magnitude of this "indentation size effect" is best described by a power-law with exponents of -0.12 +/- 0.06 and -0.18 +/- 0.08 for the Corona Heights and Yair Faults, respectively. These results demonstrate a link between surface roughness and yield stress, and suggest that fault geometry is the physical

FACTORIAL VALIDITY OF THE KOREAN VERSION OF THE EXERCISE DEPENDENCE SCALE-REVISED.

Science.gov (United States)

Shin, Kyulee; You, Sukkyung

2015-12-01

This study evaluated the psychometric properties of the Korean version of the 21-item Exercise Dependence Scale-Revised (EDS-R). The EDS-R was designed to measure the multidimensional aspects of exercise dependence symptoms such as withdrawal, continuance, tolerance, lack of control, reductions, time, and intention. Although the EDS-R has demonstrated sound psychometric properties, it has only been validated in Western samples. Cross-cultural validations of the instrument may increase the knowledge of exercise dependence. Therefore, this study aimed to contribute to the file by investigating the validity and utility of the construct of the EDS-R, using a non-Western sample. 402 adult participants who were over 18 years of age and who reported exercising at least once a week were asked to complete the EDS-R. The results from factor analyses supported that the seven-factor model of exercise dependence symptoms showed an adequate fit for both men and women. The EDS-R scores differentiated between samples, with varying amounts of exercise; 15.4% of the sample was classified as being at risk for exercise dependence. In sum, the results indicated that the EDS-R is a psychometrically reliable assessment tool for exercise dependence symptoms in Korea.

Origin of Scale-Dependent Dispersivity and Its Implications For Miscible Gas Flooding

Energy Technology Data Exchange (ETDEWEB)

Steven Bryant; Russ Johns; Larry Lake; Thomas Harmon

2008-09-30

Dispersive mixing has an important impact on the effectiveness of miscible floods. Simulations routinely assume Fickian dispersion, yet it is well established that dispersivity depends on the scale of measurement. This is one of the main reasons that a satisfactory method for design of field-scale miscible displacement processes is still not available. The main objective of this project was to improve the understanding of the fundamental mechanisms of dispersion and mixing, particularly at the pore scale. To this end, microsensors were developed and used in the laboratory to measure directly the solute concentrations at the scale of individual pores; the origin of hydrodynamic dispersion was evaluated from first principles of laminar flow and diffusion at the grain scale in simple but geometrically completely defined porous media; techniques to use flow reversal to distinguish the contribution to dispersion of convective spreading from that of true mixing; and the field scale impact of permeability heterogeneity on hydrodynamic dispersion was evaluated numerically. This project solved a long-standing problem in solute transport in porous media by quantifying the physical basis for the scaling of dispersion coefficient with the 1.2 power of flow velocity. The researchers also demonstrated that flow reversal uniquely enables a crucial separation of irreversible and reversible contributions to mixing. The interpretation of laboratory and field experiments that include flow reversal provides important insight. Other advances include the miniaturization of long-lasting microprobes for in-situ, pore-scale measurement of tracers, and a scheme to account properly in a reservoir simulator (grid-block scale) for the contributions of convective spreading due to reservoir heterogeneity and of mixing.

Land Use in LCIA: an absolute scale proposal for Biotic Production Potential

DEFF Research Database (Denmark)

Saez de Bikuna Salinas, Koldo; Ibrom, Andreas; Hauschild, Michael Zwicky

, the present study proposes a single absolute scale for the midpoint impact category (MIC) of Biotic Production Potential (BPP). It is hypothesized that, for an ecosystem in equilibrium (where NPP equals decay), such an ecosystem has reached the maximum biotic throughput subject to site-specific conditions...... and no externally added inputs. The original ecosystem (or Potential Natural Vegetation) of a certain land gives then the maximum BPP with no additional, downstream or upstream, impacts. This Natural BPP is proposed as the maximum BPP in a hypothetical Absolute Scale for LCA’s Land Use framework. It is argued...... that this maximum BPP is Nature’s optimal solution through evolution-adaptation mechanisms, which provides the maximum matter throughput subject to the rest of environmental constraints (without further impacts). As a consequence, this scale rises a Land Use Optimality Point that suggests the existence of a limit...

Transport sensitivity studies for SITE-94: Time-dependent site-scale modelling of future glacial impact

International Nuclear Information System (INIS)

King-Clayton, L.; Smith, Paul

1996-10-01

The report details the methodology and preliminary results from the modelling of radionuclide transport from a hypothetical repository based at the Aespoe site in Sweden. The work complements and utilizes the results from regional-scale, variable density flow modelling by Provost, in which the groundwater flow field is time dependent, reflecting the impact of climate evolution over the next 130,000 years. The climate evolution include development of permafrost conditions and ice sheet advance and retreat. The results indicate that temporal changes in flow conditions owing to future climate changes have a significant effect on the transport of radionuclides from a repository. In all cases modelled with time-dependent boundary conditions, the greatest radionuclide fluxes occur towards the end of the main glacial periods, and correspond to periods of high groundwater discharge at the margin of the modelled ice sheets. Fluxes to the biosphere may, for limited periods (2000 years or less), be three times higher than those from the near field. The study provides a quantitative way of illustrating the possible effects of future glaciations on radionuclide transport from the repository. Such effects are likely to be significant in any potential siting area predicted to be affected by future periods of ice cover. 8 refs, 22 tabs, 119 figs

Bohr Hamiltonian with an energy-dependent γ-unstable Coulomb-like potential

Energy Technology Data Exchange (ETDEWEB)

Budaca, R. [Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

2016-10-15

An exact analytical solution for the Bohr Hamiltonian with an energy-dependent Coulomb-like γ-unstable potential is presented. Due to the linear energy dependence of the potential's coupling constant, the corresponding spectrum in the asymptotic limit of the slope parameter resembles the spectral structure of the spherical vibrator, however with a different state degeneracy. The parameter free energy spectrum as well as the transition rates for this case are given in closed form and duly compared with those of the harmonic U(5) dynamical symmetry. The model wave functions are found to exhibit properties that can be associated to shape coexistence. A possible experimental realization of the model is found in few medium nuclei with a very low second 0{sup +} state known to exhibit competing prolate, oblate and spherical shapes. (orig.)

[Ion-dependency of the GABA-potentiating effects of benzodiazepine tranquilizers and harmane].

Science.gov (United States)

Abramets, I I; Komissarov, I V

1984-06-01

Experiments on an isolated spinal cord of 8-15-day-old rats have shown that one of the possible mechanisms of the GABA-potentiating action of the benzodiazepine tranquilizer, chlorodiazepoxide, may be a decrease in the intraneuronal concentration of Ca2+. This is evidenced by the enhancement of the GABA-potentiating action of chlorodiazepoxide under Ca2+ deficiency in the medium and in the presence of the blockers of the voltage-dependent Ca2+ ionic channels--Mn2+ and Co2+, and by the reduction of the effect in question under Ca2+ excess in the medium and in the presence of the K+ channels blockers--tetraethylammonium and 4-aminopyridine. The GABA-potentiating action of harmane is likely to be related to the blockade of the voltage-dependent K+ channels and elevation of the intracellular concentration of Ca2+.

Parity dependence in the optical potential of sd-shell nuclei

International Nuclear Information System (INIS)

Ferrero, J.L.; Ruiz, J.A.; Bilwes, B.; Bilwes, R.

1989-01-01

Elastic scattering between sd-shell nuclei differing by one, two, three and four nucleons has been measured. The oscillating pattern of the angular distributions, when it is observed, is attributed to the interference between direct elastic scattering and elastic transfer. Explicit DWBA treatment of the elastic transfer or parity dependent real potential analysis allow both a good reproduction of the data. The sign and the importance of the parity potential deduced by fitting the data are in good agreement with the predictions of microscopic calculations in the two centre shell-model

Effective potentials for supersymmetric three-scale hierarchies

International Nuclear Information System (INIS)

Polchinski, J.

1983-01-01

We consider the effective potential in models in which supersymmetry breaks at a scale μ but the Goldstone fermion couples only to fields of mass M>>μ. We show that all large perturbative logarithms are removed by taking the renormalization point to be O(M). This makes it possible to calculate the effective potential at large X in those inverted-hierarchy models where the Goldstone fermion couples only to superheavy fields. A general formula for the one-loop logarithm in these models is given. We illustrate the results with an SU(n) example in which the direction as well as the magnitude of the gauge symmetry breaking is undetermined at the tree level. For this example a large perturbative hierarchy does not form and the unbroken subgroup is always SU(n-1) x U(1). In an appendix we show that O'Raifeartaigh models with just one undetermined scalar field always have a decoupled Goldstone fermion when the undetermined field is large, but that this need not be true in more general inverted-hierarchy models

Factorial Validity and Invariance Testing of the Exercise Dependence Scale-Revised in Swedish and Portuguese Exercisers

Science.gov (United States)

Lindwall, Magnus; Palmeira, Antonio

2009-01-01

The present study investigated the factorial validity and factorial invariance of the 21-item Exercise Dependence Scale-Revised using 162 Swedish and 269 Portuguese exercisers. In addition, the prevalence of exercise dependence symptoms and links to exercise behavior, gender, and age in the two samples was also studied. Confirmatory factor…

Revising the potential of large-scale Jatropha oil production in Tanzania: An economic land evaluation assessment

International Nuclear Information System (INIS)

Segerstedt, Anna; Bobert, Jans

2013-01-01

Following up the rather sobering results of the biofuels boom in Tanzania, we analyze the preconditions that would make large-scale oil production from the feedstock Jatropha curcas viable. We do this by employing an economic land evaluation approach; first, we estimate the physical land suitability and the necessary inputs to reach certain amounts of yields. Subsequently, we estimate costs and benefits for different input-output levels. Finally, to incorporate the increased awareness of sustainability in the export sector, we introduce also certification criteria. Using data from an experimental farm in Kilosa, we find that high yields are crucial for the economic feasibility and that they can only be obtained on good soils at high input rates. Costs of compliance with certification criteria depend on site specific characteristics such as land suitability and precipitation. In general, both domestic production and (certified) exports are too expensive to be able to compete with conventional diesel/rapeseed oil from the EU. Even though the crop may have potential for large scale production as a niche product, there is still a lot of risk involved and more experimental research is needed. - Highlights: ► We use an economic land evaluation analysis to reassess the potential of large-scale Jatropha oil. ► High yields are possible only at high input rates and for good soil qualities. ► Production costs are still too high to break even on the domestic and export market. ► More research is needed to stabilize yields and improve the oil content. ► Focus should be on broadening our knowledge-base rather than promoting new Jatropha investments

Flecainide associated torsade de pointes: A potential case of reverse use dependence

Directory of Open Access Journals (Sweden)

Kevin Hayes

2013-01-01

Full Text Available Flecainide has been known to cause torsades de pointes (TdP in patients with structural heart disease and its mechanism has been attributed to use-dependency. We present a patient with flecainide-induced TdP in the absence of any other precipitating factors. This case highlights potential reverse use dependence associated with flecainide resulting in TdP.

Dependency on scale of power numbers of Rushton disc turbines

Energy Technology Data Exchange (ETDEWEB)

Bujalski, W.; Nienow, A.W.; Chatwin, S.; Cooke, M.

1987-01-01

Extensive and very accurate power numbers have been obtained for a wide range of Rushton disc turbines using water as the working fluid in six fully baffled vessels from 0.22 to 1.83 m diameter. The results show that for Reynolds numbers greater than or equal to 2 x 10/sup 4/, the average peak power number anti Po is dependent on the disc thickness (x/sub 1/) to impeller diameter (D) ratio and to the vessel diameter (T). Provided x/sub 1//D is constant, anti Po is independent of impeller to vessel ratio in the range 0.25 less than or equal to D/T less than or equal to 0.70. For 0.01 less than or equal to x/sub 1//D less than or equal to 0.05 and for the range of vessels studied, the equation anti Po = 2.5(x/sub 1//D)/sup -0.2/ (T/T/sub 0/)/sup 0.065/ fitted the data to within +/- 3% where T/sub 0/ is a 1 m diameter vessel. An F-test shows that the inclusion of the small effect of scale, (T/T/sub 0/), is statistically significant at the 99% level. The implications of these scale and geometrical effects for mixing research, process design and scale-up are discussed.

The scale-dependent market trend: Empirical evidences using the lagged DFA method

Science.gov (United States)

Li, Daye; Kou, Zhun; Sun, Qiankun

2015-09-01

In this paper we make an empirical research and test the efficiency of 44 important market indexes in multiple scales. A modified method based on the lagged detrended fluctuation analysis is utilized to maximize the information of long-term correlations from the non-zero lags and keep the margin of errors small when measuring the local Hurst exponent. Our empirical result illustrates that a common pattern can be found in the majority of the measured market indexes which tend to be persistent (with the local Hurst exponent > 0.5) in the small time scale, whereas it displays significant anti-persistent characteristics in large time scales. Moreover, not only the stock markets but also the foreign exchange markets share this pattern. Considering that the exchange markets are only weakly synchronized with the economic cycles, it can be concluded that the economic cycles can cause anti-persistence in the large time scale but there are also other factors at work. The empirical result supports the view that financial markets are multi-fractal and it indicates that deviations from efficiency and the type of model to describe the trend of market price are dependent on the forecasting horizon.

Josephson-like currents in graphene for arbitrary time-dependent potential barriers

OpenAIRE

Savel'ev, Sergey E.; Hausler, Wolfgang; Hanggi, Peter

2011-01-01

From the exact solution of the Dirac-Weyl equation we find unusual currents j_y running in y-direction parallel to a time-dependent scalar potential barrier W(x,t) placed upon a monolayer of graphene, even for vanishing momentum component p_y. In their sine-like dependence on the phase difference of wave functions, describing left and right moving Dirac fermions, these currents resemble Josephson currents in superconductors, including the occurance of Shapiro steps at certain frequencies of p...

Learning of Precise Spike Times with Homeostatic Membrane Potential Dependent Synaptic Plasticity.

Directory of Open Access Journals (Sweden)

Christian Albers

Full Text Available Precise spatio-temporal patterns of neuronal action potentials underly e.g. sensory representations and control of muscle activities. However, it is not known how the synaptic efficacies in the neuronal networks of the brain adapt such that they can reliably generate spikes at specific points in time. Existing activity-dependent plasticity rules like Spike-Timing-Dependent Plasticity are agnostic to the goal of learning spike times. On the other hand, the existing formal and supervised learning algorithms perform a temporally precise comparison of projected activity with the target, but there is no known biologically plausible implementation of this comparison. Here, we propose a simple and local unsupervised synaptic plasticity mechanism that is derived from the requirement of a balanced membrane potential. Since the relevant signal for synaptic change is the postsynaptic voltage rather than spike times, we call the plasticity rule Membrane Potential Dependent Plasticity (MPDP. Combining our plasticity mechanism with spike after-hyperpolarization causes a sensitivity of synaptic change to pre- and postsynaptic spike times which can reproduce Hebbian spike timing dependent plasticity for inhibitory synapses as was found in experiments. In addition, the sensitivity of MPDP to the time course of the voltage when generating a spike allows MPDP to distinguish between weak (spurious and strong (teacher spikes, which therefore provides a neuronal basis for the comparison of actual and target activity. For spatio-temporal input spike patterns our conceptually simple plasticity rule achieves a surprisingly high storage capacity for spike associations. The sensitivity of the MPDP to the subthreshold membrane potential during training allows robust memory retrieval after learning even in the presence of activity corrupted by noise. We propose that MPDP represents a biophysically plausible mechanism to learn temporal target activity patterns.

Learning of Precise Spike Times with Homeostatic Membrane Potential Dependent Synaptic Plasticity.

Science.gov (United States)

Albers, Christian; Westkott, Maren; Pawelzik, Klaus

2016-01-01

Precise spatio-temporal patterns of neuronal action potentials underly e.g. sensory representations and control of muscle activities. However, it is not known how the synaptic efficacies in the neuronal networks of the brain adapt such that they can reliably generate spikes at specific points in time. Existing activity-dependent plasticity rules like Spike-Timing-Dependent Plasticity are agnostic to the goal of learning spike times. On the other hand, the existing formal and supervised learning algorithms perform a temporally precise comparison of projected activity with the target, but there is no known biologically plausible implementation of this comparison. Here, we propose a simple and local unsupervised synaptic plasticity mechanism that is derived from the requirement of a balanced membrane potential. Since the relevant signal for synaptic change is the postsynaptic voltage rather than spike times, we call the plasticity rule Membrane Potential Dependent Plasticity (MPDP). Combining our plasticity mechanism with spike after-hyperpolarization causes a sensitivity of synaptic change to pre- and postsynaptic spike times which can reproduce Hebbian spike timing dependent plasticity for inhibitory synapses as was found in experiments. In addition, the sensitivity of MPDP to the time course of the voltage when generating a spike allows MPDP to distinguish between weak (spurious) and strong (teacher) spikes, which therefore provides a neuronal basis for the comparison of actual and target activity. For spatio-temporal input spike patterns our conceptually simple plasticity rule achieves a surprisingly high storage capacity for spike associations. The sensitivity of the MPDP to the subthreshold membrane potential during training allows robust memory retrieval after learning even in the presence of activity corrupted by noise. We propose that MPDP represents a biophysically plausible mechanism to learn temporal target activity patterns.

Scale-dependent climatic drivers of human epidemics in ancient China.

Science.gov (United States)

Tian, Huidong; Yan, Chuan; Xu, Lei; Büntgen, Ulf; Stenseth, Nils C; Zhang, Zhibin

2017-12-05

A wide range of climate change-induced effects have been implicated in the prevalence of infectious diseases. Disentangling causes and consequences, however, remains particularly challenging at historical time scales, for which the quality and quantity of most of the available natural proxy archives and written documentary sources often decline. Here, we reconstruct the spatiotemporal occurrence patterns of human epidemics for large parts of China and most of the last two millennia. Cold and dry climate conditions indirectly increased the prevalence of epidemics through the influences of locusts and famines. Our results further reveal that low-frequency, long-term temperature trends mainly contributed to negative associations with epidemics, while positive associations of epidemics with droughts, floods, locusts, and famines mainly coincided with both higher and lower frequency temperature variations. Nevertheless, unstable relationships between human epidemics and temperature changes were observed on relatively smaller time scales. Our study suggests that an intertwined, direct, and indirect array of biological, ecological, and societal responses to different aspects of past climatic changes strongly depended on the frequency domain and study period chosen.

Development and psychometric evaluation of the psychological cigarette dependence scale for male smokers in taiwan.

Science.gov (United States)

Huang, Chih-Ling; Cheng, Chung-Ping; Wang, Hsiu-Hung

2014-06-01

The influence of psychological factors on cigarette dependence often surpasses the direct effects of the nicotine itself. Researcher opinions on the nature and extent of psychological contributors to cigarette dependence vary widely. This study develops and psychometrically tests the Psychological Cigarette Dependence Scale (PCDS) for male smokers in Taiwan. The PCDS was developed using domain identification, individual interviews for item generation, expert reviews, and testing for construct validity and instrument stability. After initial item analysis, the PCDS was tested for concurrent and construct validity and reliability on 256 adult male smokers recruited from community centers, trade and business organizations, private companies, and factories in southern Taiwan. Participants were limited to adult men because female smokers are a small (4.1%) proportion of the female population in Taiwan and thus are difficult to recruit in statistically significant numbers. Exploratory factor analysis showed that lifelong binding and health concerns are the two predominating factors addressed by the 37-item PCDS. The PCDS correlated positively with the Fagerstrom questionnaire (r = .54, p < .01). Cronbach's alpha was .94, and test-retest reliability (intraclass coefficient) was .77 (N = 28). Preliminary evidence suggests that this scale is a valid measure of psychological cigarette dependence. Assessment results may help nursing professionals focus on smoking cessation interventions that are tailored to the patterns and severity of patients' psychological cigarette dependence.

l-dependent potential barriers and superdeformed states

International Nuclear Information System (INIS)

Gherghescu, R.A.; Royer, G.

1999-01-01

The macroscopic-microscopic energy of rotating nuclei moving in the fusion-like deformation valley has been determined within a generalized liquid drop model including the nuclear proximity energy, the two-center shell model and the Strutinsky method. The l-dependent potential barriers of the 84 Zr, 132 Ce, 152 Dy and 192 Hg nuclei have been determined. A first minimum having a pure microscopic origin and lodging the normally deformed states, progressively disappears with increasing angular momenta. The microscopic and macroscopic energies contribute to generate a second minimum where superdeformed states may survive. It becomes progressively the lowest one at intermediate spins. At still higher angular momenta, the minimum moves towards the foot of the external fission barrier leading to macroscopic hyper-deformed quasi-molecular states. (authors)

Spin-dependent scattering by a potential barrier on a nanotube

International Nuclear Information System (INIS)

Abranyos, Yonatan; Gumbs, Godfrey; Fekete, Paula

2010-01-01

The electron spin effects on the surface of a nanotube have been considered through the spin-orbit interaction (SOI), arising from the electron confinement on the surface of the nanotube. This is of the same nature as the Rashba-Bychkov SOI at a semiconductor heterojunction. We estimate the effect of disorder within a potential barrier on the transmission probability. Using a continuum model, we obtain analytic expressions for the spin-split energy bands for electrons on the surface of nanotubes in the presence of SOI. First we calculate analytically the amplitudes of scattering from a potential barrier located around the axis of the nanotube into spin-dependent states. The effect of disorder on the scattering process is included phenomenologically and induces a reduction in the transition probability. We analyze the relative role of SOI and disorder in the transmission probability which depends on the angular and linear momentum of the incoming particle, and its spin orientation. Finally we demonstrate that in the presence of disorder, perfect transmission may not be achieved for finite barrier heights.

Seasonal dependence of large-scale Birkeland currents

International Nuclear Information System (INIS)

Fujii, R.; Iijima, T.; Potemra, T.A.; Sugiura, M.

1981-01-01

The seasonal dependence of large-scale Birkeland currents has been determined from the analysis of vector magnetic field data acquired by the TRIAD satellite in the northern hemisphere. Statistical characteristics of single sheet (i.e., net currents) and double sheet Birkeland currents were determined from 555 TRIAD passes during the summer, and 408 passes during the winter (more complicated multiple-sheet current systems were not included in this study). The average K/sub p/ value for the summer events is 1.9 and for the winter events is 2.0. The principal results include the following: (1) The single sheet Birkeland currents are statistically observed more often than the double sheet currents in the dayside of the auroral zone during any season. The single sheet currents are also observed more often in the summer than in the winter (as much as 2 to 3 times as often depending upon the MLT sector). (2) The intensities of the single and double sheet Birkeland currents on the dayside, from approximately 1000 MLT to 1800 MLT, are larger during the summer (in comparison to winter) by a factor of about 2. (3) The intensities of the double sheet Birkeland currents in the nightside (the dominant system in this local time) do not show a significant difference from summer to winter. (4) The single and double sheet currents in the dayside (between 0600 and 1800 MLT) appear at higher latitudes (by about 1 0 to 3 0 ) during the summer in comparison to the winter. These characterisctis suggest that the Birkeland current intensities are controlled by the ionosphere conductivity in the polar region. The greater occurrence of single sheet Birkeland currents during the summertime supports the suggestion that these currents close via the polar cap when the conductivity there is sufficiently high to permit it

Extended consolidation of scaling laws of potentials covering over the representative tandem-mirror operations in GAMMA 10

International Nuclear Information System (INIS)

Cho, T.

2002-01-01

(i) A verification of our novel proposal of extended consolidation of the two major theories of Cohen's potential formation and Pastukhov's potential effectiveness is carried out by the use of a novel experimental mode with central ECH. The validity of the proposal provides a roadmap of bridging and combining two present representative modes in GAMMA 10 for upgrading to hot-ion plasmas with high potentials. (ii) A novel efficient scaling of ion-confining potential formation due to plug ECH with barrier ECH is constructed as the extension over the IAEA 2000 scaling with plug ECH alone. The combination of the physics scaling of (i) with the externally controllable power scaling of (ii) provides a scalable way for future tandem-mirror researches. The importance of the validity of the present consolidation is highlighted by a possibility of the extended capability inherent in Pastukhov's prediction of requiring 30 kV potentials for a fusion Q of unity with an application of Cohen's potential formation method. (author)

Suicide-Related Experiences Among Blacks: An Empirical Test of a Suicide Potential Scale

Science.gov (United States)

Wenz, Friedrich V.

1978-01-01

Developing a Suicide Potential Scale for a number of socially differentiated, stratified census tract populations in a northern city, this paper argues that scores on this scale are related to actual suicidal behavior. These data support the position that variation in suicide among blacks is mainly determined by economic status. (Author)

A Tentative Analysis of the Use of Potential by Commercial Bank in Controlling Credit Scale

Institute of Scientific and Technical Information of China (English)

YANG Wen-ze

2008-01-01

This article brings forward the conception of potential and filed potential in bank's competition under the inspiration of law of electric current in electrodynamics.It discusses the impact of potential shifting on commercial bank's credit scale and builds up a model for commercial bank to control the scale by credit pricing and risk policy in a dynamic way, and also gives some advice to domestic commercial bank for improving loan business, aiming to settle down the existing credit management problems.

Generalization and consolidation of scaling laws of potential formation and associated effects in the GAMMA 10 tandem mirror

International Nuclear Information System (INIS)

Cho, T.; Hirata, M.; Hojo, H.; Ichimura, M.; Ishii, K.; Itakura, A.; Katanuma, I.; Kohagura, J.; Nakashima, Y.; Saito, T.; Tanaka, S.; Tatematsu, Y.; Yoshikawa, M.; Numakura, T.; Minami, R.; Nagashima, S.; Watanabe, H.; Yoshida, M.; Sakamoto, Y.; Tamano, T.; Yatsu, K.; Miyoshi, S.

2001-01-01

Generalized scaling laws for the formation of plasma confining potentials and the associated effectiveness of the potentials produced are systematically investigated to find the physics essentials common to the representative tandem mirror operational modes of GAMMA 10, and to explore novel extended operational modes from the scaling bases constructed. (a) The potential formation scalings are generalized using a novel finding of wider validity of Cohen's strong ECH theory covering the representative modes. (b) The potentials produced, in turn, provide a favourable novel scaling of the increase in the central cell electron temperatures T e with increasing thermal barrier potentials φ b , limited by the available ECH power. The scaling of T e with φ b is well interpreted in terms of the generalized Pastukhov theory of plasma potential confinement. A detailed comparison of the results from several related modified theories is also made. (c) Consolidation of the two major scalings of (a) and (b) in a tandem mirror is carried out by the use of an electron energy balance equation for the first time. In addition, (d) an empirical scaling of φ c with ECH power in the plug region and the central cell densities are studied to discover whether there is the possibility of extending these theoretically well interpreted scaling data to parameters in the future scalable regime. There is also a discussion about numerical scalings in the three dimensional parameter spaces. (author)

The scale dependence of optical diversity in a prairie ecosystem

Science.gov (United States)

Gamon, J. A.; Wang, R.; Stilwell, A.; Zygielbaum, A. I.; Cavender-Bares, J.; Townsend, P. A.

2015-12-01

Biodiversity loss, one of the most crucial challenges of our time, endangers ecosystem services that maintain human wellbeing. Traditional methods of measuring biodiversity require extensive and costly field sampling by biologists with extensive experience in species identification. Remote sensing can be used for such assessment based upon patterns of optical variation. This provides efficient and cost-effective means to determine ecosystem diversity at different scales and over large areas. Sampling scale has been described as a "fundamental conceptual problem" in ecology, and is an important practical consideration in both remote sensing and traditional biodiversity studies. On the one hand, with decreasing spatial and spectral resolution, the differences among different optical types may become weak or even disappear. Alternately, high spatial and/or spectral resolution may introduce redundant or contradictory information. For example, at high resolution, the variation within optical types (e.g., between leaves on a single plant canopy) may add complexity unrelated to specie richness. We studied the scale-dependence of optical diversity in a prairie ecosystem at Cedar Creek Ecosystem Science Reserve, Minnesota, USA using a variety of spectrometers from several platforms on the ground and in the air. Using the coefficient of variation (CV) of spectra as an indicator of optical diversity, we found that high richness plots generally have a higher coefficient of variation. High resolution imaging spectrometer data (1 mm pixels) showed the highest sensitivity to richness level. With decreasing spatial resolution, the difference in CV between richness levels decreased, but remained significant. These findings can be used to guide airborne studies of biodiversity and develop more effective large-scale biodiversity sampling methods.

Size-dependent elastic/inelastic behavior of enamel over millimeter and nanometer length scales.

Science.gov (United States)

Ang, Siang Fung; Bortel, Emely L; Swain, Michael V; Klocke, Arndt; Schneider, Gerold A

2010-03-01

The microstructure of enamel like most biological tissues has a hierarchical structure which determines their mechanical behavior. However, current studies of the mechanical behavior of enamel lack a systematic investigation of these hierarchical length scales. In this study, we performed macroscopic uni-axial compression tests and the spherical indentation with different indenter radii to probe enamel's elastic/inelastic transition over four hierarchical length scales, namely: 'bulk enamel' (mm), 'multiple-rod' (10's microm), 'intra-rod' (100's nm with multiple crystallites) and finally 'single-crystallite' (10's nm with an area of approximately one hydroxyapatite crystallite). The enamel's elastic/inelastic transitions were observed at 0.4-17 GPa depending on the length scale and were compared with the values of synthetic hydroxyapatite crystallites. The elastic limit of a material is important as it provides insights into the deformability of the material before fracture. At the smallest investigated length scale (contact radius approximately 20 nm), elastic limit is followed by plastic deformation. At the largest investigated length scale (contact size approximately 2 mm), only elastic then micro-crack induced response was observed. A map of elastic/inelastic regions of enamel from millimeter to nanometer length scale is presented. Possible underlying mechanisms are also discussed. (c) 2009 Elsevier Ltd. All rights reserved.

Transition physics and scaling overview

International Nuclear Information System (INIS)

Carlstrom, T.N.

1996-01-01

This paper presents an overview of recent experimental progress towards understanding H-mode transition physics and scaling. Terminology and techniques for studying H-mode are reviewed and discussed. The model of shear E x B flow stabilization of edge fluctuations at the L-H transition is gaining wide acceptance and is further supported by observations of edge rotation on a number of new devices. Observations of poloidal asymmetries of edge fluctuations and dephasing of density and potential fluctuations after the transition pose interesting challenges for understanding H-mode physics. Dedicated scans to determine the scaling of the power threshold have now been performed on many machines. A clear B t dependence is universally observed but dependence on the line averaged density is complicated. Other dependencies are also reported. Studies of the effect of neutrals and error fields on the power threshold are under investigation. The ITER threshold database has matured and offers guidance to the power threshold scaling issues relevant to next-step devices. (author)

Transition physics and scaling overview

International Nuclear Information System (INIS)

Carlstrom, T.N.

1995-12-01

This paper presents an overview of recent experimental progress towards understanding H-mode transition physics and scaling. Terminology and techniques for studying H-mode are reviewed and discussed. The model of shear E x B flow stabilization of edge fluctuations at the L-H transition is gaining wide acceptance and is further supported by observations of edge rotation on a number of new devices. Observations of poloidal asymmetries of edge fluctuations and dephasing of density and potential fluctuations after the transition pose interesting challenges for understanding H-mode physics. Dedicated scans to determine the scaling of the power threshold have now been performed on many machines. A dear B t dependence is universally observed but dependence on the line averaged density is complicated. Other dependencies are also reported. Studies of the effect of neutrals and error fields on the power threshold are under investigation. The ITER threshold database has matured and offers guidance to the power threshold scaling issues relevant to next-step devices

Energy dependence of the 16O + 12C potential of interaction

Directory of Open Access Journals (Sweden)

O. A. Ponkratenko

2013-09-01

Full Text Available The 16O + 12C scattering data originating from various measurements in the energy range from 1 to 100 MeV/nucleon have been analyzed within optical model (OM. As a result the global energy dependent 16O + 12C - OM-potential has been obtained. Satisfactory description of experimental data is achieved. While analyzing differential cross sections of the elastic scattering and fusion cross sections were calculated using var-ious types of optical potentials.

Potential and flux field landscape theory. I. Global stability and dynamics of spatially dependent non-equilibrium systems.

Science.gov (United States)

Wu, Wei; Wang, Jin

2013-09-28

We established a potential and flux field landscape theory to quantify the global stability and dynamics of general spatially dependent non-equilibrium deterministic and stochastic systems. We extended our potential and flux landscape theory for spatially independent non-equilibrium stochastic systems described by Fokker-Planck equations to spatially dependent stochastic systems governed by general functional Fokker-Planck equations as well as functional Kramers-Moyal equations derived from master equations. Our general theory is applied to reaction-diffusion systems. For equilibrium spatially dependent systems with detailed balance, the potential field landscape alone, defined in terms of the steady state probability distribution functional, determines the global stability and dynamics of the system. The global stability of the system is closely related to the topography of the potential field landscape in terms of the basins of attraction and barrier heights in the field configuration state space. The effective driving force of the system is generated by the functional gradient of the potential field alone. For non-equilibrium spatially dependent systems, the curl probability flux field is indispensable in breaking detailed balance and creating non-equilibrium condition for the system. A complete characterization of the non-equilibrium dynamics of the spatially dependent system requires both the potential field and the curl probability flux field. While the non-equilibrium potential field landscape attracts the system down along the functional gradient similar to an electron moving in an electric field, the non-equilibrium flux field drives the system in a curly way similar to an electron moving in a magnetic field. In the small fluctuation limit, the intrinsic potential field as the small fluctuation limit of the potential field for spatially dependent non-equilibrium systems, which is closely related to the steady state probability distribution functional, is

Flat tree-level inflationary potentials in the light of cosmic microwave background and large scale structure data

CERN Document Server

Ballesteros, G; Espinosa, J R; de Austri, R Ruiz; Trotta, R

2008-01-01

We use cosmic microwave background and large scale structure data to test a broad and physically well-motivated class of inflationary models: those with flat tree-level potentials (typical in supersymmetry). The non-trivial features of the potential arise from radiative corrections which give a simple logarithmic dependence on the inflaton field, making the models very predictive. We also consider a modified scenario with new physics beyond a certain high-energy cut-off showing up as non-renormalizable operators (NRO) in the inflaton field. We find that both kinds of models fit remarkably well CMB and LSS data, with very few free parameters. Besides, a large part of these models naturally predict a reasonable number of e-folds. A robust feature of these scenarios is the smallness of tensor perturbations (r < 10^{-3}). The NRO case can give a sizeable running of the spectral index while achieving a sufficient number of e-folds. We use Bayesian model comparison tools to assess the relative performance of the...

IDENTIFYING POTENTIAL MARKERS OF THE SUN'S GIANT CONVECTIVE SCALE

Energy Technology Data Exchange (ETDEWEB)

McIntosh, Scott W.; Wang, Xin [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Scherrer, Philip H. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

2014-04-01

Line-of-sight magnetograms from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory (SDO) are analyzed using a diagnostic known as the magnetic range of influence (MRoI). The MRoI is a measure of the length over which a photospheric magnetogram is balanced and so its application gives the user a sense of the connective length scales in the outer solar atmosphere. The MRoI maps and histograms inferred from the SDO/HMI magnetograms primarily exhibit four scales: a scale of a few megameters that can be associated with granulation, a scale of a few tens of megameters that can be associated with super-granulation, a scale of many hundreds to thousands of megameters that can be associated with coronal holes and active regions, and a hitherto unnoticed scale that ranges from 100 to 250 Mm. We infer that this final scale is an imprint of the (rotationally driven) giant convective scale on photospheric magnetism. This scale appears in MRoI maps as well-defined, spatially distributed concentrations that we have dubbed ''g-nodes''. Furthermore, using coronal observations from the Atmospheric Imaging Assembly on SDO, we see that the vicinity of these g-nodes appears to be a preferred location for the formation of extreme-ultraviolet (and likely X-Ray) brightpoints. These observations and straightforward diagnostics offer the potential of a near real-time mapping of the Sun's largest convective scale, a scale that possibly reaches to the very bottom of the convective zone.

State-dependent fluorescence of neutral atoms in optical potentials

Science.gov (United States)

Martinez-Dorantes, M.; Alt, W.; Gallego, J.; Ghosh, S.; Ratschbacher, L.; Meschede, D.

2018-02-01

Recently we have demonstrated scalable, nondestructive, and high-fidelity detection of the internal state of 87Rb neutral atoms in optical dipole traps using state-dependent fluorescence imaging [M. Martinez-Dorantes, W. Alt, J. Gallego, S. Ghosh, L. Ratschbacher, Y. Völzke, and D. Meschede, Phys. Rev. Lett. 119, 180503 (2017), 10.1103/PhysRevLett.119.180503]. In this paper we provide experimental procedures and interpretations to overcome the detrimental effects of heating-induced trap losses and state leakage. We present models for the dynamics of optically trapped atoms during state-dependent fluorescence imaging and verify our results by comparing Monte Carlo simulations with experimental data. Our systematic study of dipole force fluctuations heating in optical traps during near-resonant illumination shows that off-resonant light is preferable for state detection in tightly confining optical potentials.

Coarsening of stripe patterns: variations with quench depth and scaling.

Science.gov (United States)

Tripathi, Ashwani K; Kumar, Deepak

2015-02-01

The coarsening of stripe patterns when the system is evolved from random initial states is studied by varying the quench depth ε, which is a measure of distance from the transition point of the stripe phase. The dynamics of the growth of stripe order, which is characterized by two length scales, depends on the quench depth. The growth exponents of the two length scales vary continuously with ε. The decay exponents for free energy, stripe curvature, and densities of defects like grain boundaries and dislocations also show similar variation. This implies a breakdown of the standard picture of nonequilibrium dynamical scaling. In order to understand the variations with ε we propose an additional scaling with a length scale dependent on ε. The main contribution to this length scale comes from the "pinning potential," which is unique to systems where the order parameter is spatially periodic. The periodic order parameter gives rise to an ε-dependent potential, which can pin defects like grain boundaries, dislocations, etc. This additional scaling provides a compact description of variations of growth exponents with quench depth in terms of just one exponent for each of the length scales. The relaxation of free energy, stripe curvature, and the defect densities have also been related to these length scales. The study is done at zero temperature using Swift-Hohenberg equation in two dimensions.

Scaling-law for the energy dependence of anatomic power spectrum in dedicated breast CT

Energy Technology Data Exchange (ETDEWEB)

Vedantham, Srinivasan; Shi, Linxi; Glick, Stephen J.; Karellas, Andrew [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States)

2013-01-15

Purpose: To determine the x-ray photon energy dependence of the anatomic power spectrum of the breast when imaged with dedicated breast computed tomography (CT). Methods: A theoretical framework for scaling the empirically determined anatomic power spectrum at one x-ray photon energy to that at any given x-ray photon energy when imaged with dedicated breast CT was developed. Theory predicted that when the anatomic power spectrum is fitted with a power curve of the form k f{sup -{beta}}, where k and {beta} are fit coefficients and f is spatial frequency, the exponent {beta} would be independent of x-ray photon energy (E), and the amplitude k scales with the square of the difference in energy-dependent linear attenuation coefficients of fibroglandular and adipose tissues. Twenty mastectomy specimens based numerical phantoms that were previously imaged with a benchtop flat-panel cone-beam CT system were converted to 3D distribution of glandular weight fraction (f{sub g}) and were used to verify the theoretical findings. The 3D power spectrum was computed in terms of f{sub g} and after converting to linear attenuation coefficients at monoenergetic x-ray photon energies of 20-80 keV in 5 keV intervals. The 1D power spectra along the axes were extracted and fitted with a power curve of the form k f{sup -{beta}}. The energy dependence of k and {beta} were analyzed. Results: For the 20 mastectomy specimen based numerical phantoms used in the study, the exponent {beta} was found to be in the range of 2.34-2.42, depending on the axis of measurement. Numerical simulations agreed with the theoretical predictions that for a power-law anatomic spectrum of the form k f{sup -{beta}}, {beta} was independent of E and k(E) =k{sub 1}[{mu}{sub g}(E) -{mu}{sub a}(E)]{sup 2}, where k{sub 1} is a constant, and {mu}{sub g}(E) and {mu}{sub a}(E) represent the energy-dependent linear attenuation coefficients of fibroglandular and adipose tissues, respectively. Conclusions: Numerical

Linear Scaling Solution of the Time-Dependent Self-Consistent-Field Equations

Directory of Open Access Journals (Sweden)

Matt Challacombe

2014-03-01

Full Text Available A new approach to solving the Time-Dependent Self-Consistent-Field equations is developed based on the double quotient formulation of Tsiper 2001 (J. Phys. B. Dual channel, quasi-independent non-linear optimization of these quotients is found to yield convergence rates approaching those of the best case (single channel Tamm-Dancoff approximation. This formulation is variational with respect to matrix truncation, admitting linear scaling solution of the matrix-eigenvalue problem, which is demonstrated for bulk excitons in the polyphenylene vinylene oligomer and the (4,3 carbon nanotube segment.

Scale-dependency of the global mean surface temperature trend and its implication for the recent hiatus of global warming.

Science.gov (United States)

Lin, Yong; Franzke, Christian L E

2015-08-11

Studies of the global mean surface temperature trend are typically conducted at a single (usually annual or decadal) time scale. The used scale does not necessarily correspond to the intrinsic scales of the natural temperature variability. This scale mismatch complicates the separation of externally forced temperature trends from natural temperature fluctuations. The hiatus of global warming since 1999 has been claimed to show that human activities play only a minor role in global warming. Most likely this claim is wrong due to the inadequate consideration of the scale-dependency in the global surface temperature (GST) evolution. Here we show that the variability and trend of the global mean surface temperature anomalies (GSTA) from January 1850 to December 2013, which incorporate both land and sea surface data, is scale-dependent and that the recent hiatus of global warming is mainly related to natural long-term oscillations. These results provide a possible explanation of the recent hiatus of global warming and suggest that the hiatus is only temporary.

The Betel Quid Dependence Scale: replication and extension in a Guamanian sample.

Science.gov (United States)

Herzog, Thaddeus A; Murphy, Kelle L; Little, Melissa A; Suguitan, Gil S; Pokhrel, Pallav; Kawamoto, Crissy T

2014-05-01

Betel quid is the fourth most commonly consumed psychoactive substance in the world. The Betel Quid Dependence Scale (BQDS) is the first instrument designed specifically to measure betel quid dependence. The three factor structure of the BQDS consists of "physical and psychological urgent need," "increasing dose," and "maladaptive use." The BQDS initially was validated in a sample of male prisoner ex-chewers in Taiwan. To replicate and extend the original validation research on the BQDS in a sample of male and female current betel quid chewers in Guam. A survey containing the BQDS was administered to 300 current betel quid chewers in Guam. Participants were compensated for their time with a gift card worth $25. Confirmatory factor analysis revealed an adequate fit with the hypothesized three-factor measurement model. ANOVAs and structural equations modeling revealed that betel quid dependence is associated with the inclusion of tobacco in the quid, number of chews per day, years of chewing, and education. The BQDS is valid for current English-speaking male and female chewers in Guam. Overall levels of betel quid dependence were high, and most chewers included tobacco in their betel quid. The results suggest that levels of dependence for betel quid are similar to those observed for nicotine dependence. Future research should explore other important psychological and behavioral aspects of betel quid chewing such as health risk perceptions and motivation to quit chewing. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Darboux Transformations for Energy-Dependent Potentials and the Klein–Gordon Equation

International Nuclear Information System (INIS)

Schulze-Halberg, Axel

2013-01-01

We construct explicit Darboux transformations for a generalized Schrödinger-type equation with energy-dependent potential, a special case of which is the stationary Klein–Gordon equation. Our results complement and generalize former findings (Lin et al., Phys Lett A 362:212–214, 2007).

Decay constants of heavy mesons in the relativistic potential model with velocity dependent corrections

International Nuclear Information System (INIS)

Avaliani, I.S.; Sisakyan, A.N.; Slepchenko, L.A.

1992-01-01

In the relativistic model with the velocity dependent potential the masses and leptonic decay constants of heavy pseudoscalar and vector mesons are computed. The possibility of using this potential is discussed. 11 refs.; 4 tabs

DECK: Distance and environment-dependent, coarse-grained, knowledge-based potentials for protein-protein docking

Directory of Open Access Journals (Sweden)

Vakser Ilya A

2011-07-01

Full Text Available Abstract Background Computational approaches to protein-protein docking typically include scoring aimed at improving the rank of the near-native structure relative to the false-positive matches. Knowledge-based potentials improve modeling of protein complexes by taking advantage of the rapidly increasing amount of experimentally derived information on protein-protein association. An essential element of knowledge-based potentials is defining the reference state for an optimal description of the residue-residue (or atom-atom pairs in the non-interaction state. Results The study presents a new Distance- and Environment-dependent, Coarse-grained, Knowledge-based (DECK potential for scoring of protein-protein docking predictions. Training sets of protein-protein matches were generated based on bound and unbound forms of proteins taken from the DOCKGROUND resource. Each residue was represented by a pseudo-atom in the geometric center of the side chain. To capture the long-range and the multi-body interactions, residues in different secondary structure elements at protein-protein interfaces were considered as different residue types. Five reference states for the potentials were defined and tested. The optimal reference state was selected and the cutoff effect on the distance-dependent potentials investigated. The potentials were validated on the docking decoys sets, showing better performance than the existing potentials used in scoring of protein-protein docking results. Conclusions A novel residue-based statistical potential for protein-protein docking was developed and validated on docking decoy sets. The results show that the scoring function DECK can successfully identify near-native protein-protein matches and thus is useful in protein docking. In addition to the practical application of the potentials, the study provides insights into the relative utility of the reference states, the scope of the distance dependence, and the coarse-graining of

Defect evolution in cosmology and condensed matter quantitative analysis with the velocity-dependent one-scale model

CERN Document Server

Martins, C J A P

2016-01-01

This book sheds new light on topological defects in widely differing systems, using the Velocity-Dependent One-Scale Model to better understand their evolution. Topological defects – cosmic strings, monopoles, domain walls or others - necessarily form at cosmological (and condensed matter) phase transitions. If they are stable and long-lived they will be fossil relics of higher-energy physics. Understanding their behaviour and consequences is a key part of any serious attempt to understand the universe, and this requires modelling their evolution. The velocity-dependent one-scale model is the only fully quantitative model of defect network evolution, and the canonical model in the field. This book provides a review of the model, explaining its physical content and describing its broad range of applicability.

Anaerobic Digestion and Biogas Potential: Simulation of Lab and Industrial-Scale Processes

OpenAIRE

Ihsan Hamawand; Craig Baillie

2015-01-01

In this study, a simulation was carried out using BioWin 3.1 to test the capability of the software to predict the biogas potential for two different anaerobic systems. The two scenarios included: (1) a laboratory-scale batch reactor; and (2) an industrial-scale anaerobic continuous lagoon digester. The measured data related to the operating conditions, the reactor design parameters and the chemical properties of influent wastewater were entered into BioWin. A sensitivity analysis was carried...

A singular position-dependent mass particle in an infinite potential well

International Nuclear Information System (INIS)

Mustafa, Omar; Mazharimousavi, S. Habib

2009-01-01

An unusual singular position-dependent-mass particle in an infinite potential well is considered. The corresponding Hamiltonian is mapped through a point-canonical-transformation and an explicit correspondence between the target Hamiltonian and a Poeschl-Teller type reference Hamiltonian is obtained. New ordering ambiguity parametric setting are suggested

Length-scale dependent ensemble-averaged conductance of a 1D disordered conductor: Conductance minimum

International Nuclear Information System (INIS)

Tit, N.; Kumar, N.; Pradhan, P.

1993-07-01

Exact numerical calculation of ensemble averaged length-scale dependent conductance for the 1D Anderson model is shown to support an earlier conjecture for a conductance minimum. Numerical results can be understood in terms of the Thouless expression for the conductance and the Wigner level-spacing statistics. (author). 8 refs, 2 figs

Modeling of scale-dependent bacterial growth by chemical kinetics approach.

Science.gov (United States)

Martínez, Haydee; Sánchez, Joaquín; Cruz, José-Manuel; Ayala, Guadalupe; Rivera, Marco; Buhse, Thomas

2014-01-01

We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V) of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

Modeling of Scale-Dependent Bacterial Growth by Chemical Kinetics Approach

Directory of Open Access Journals (Sweden)

Haydee Martínez

2014-01-01

Full Text Available We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli  JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

Exponential-Six Potential Scaling for the Calculation of Tree Energies in Molecular Simulations

Czech Academy of Sciences Publication Activity Database

Sellers, M.S.; Lísal, Martin; Brennan, J.K.

2015-01-01

Roč. 113, č. 1 (2015), s. 45-54 ISSN 0026-8976 R&D Projects: GA MŠk LH12020 Grant - others:US ARL(US) W911NF-10-2-0039 Institutional support: RVO:67985858 Keywords : exponential-six potential * free energy * potential scaling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.837, year: 2015

Hierarchy of model Kohn–Sham potentials for orbital-dependent functionals: A practical alternative to the optimized effective potential method

International Nuclear Information System (INIS)

Kohut, Sviataslau V.; Staroverov, Viktor N.; Ryabinkin, Ilya G.

2014-01-01

We describe a method for constructing a hierarchy of model potentials approximating the functional derivative of a given orbital-dependent exchange-correlation functional with respect to electron density. Each model is derived by assuming a particular relationship between the self-consistent solutions of Kohn–Sham (KS) and generalized Kohn–Sham (GKS) equations for the same functional. In the KS scheme, the functional is differentiated with respect to density, in the GKS scheme—with respect to orbitals. The lowest-level approximation is the orbital-averaged effective potential (OAEP) built with the GKS orbitals. The second-level approximation, termed the orbital-consistent effective potential (OCEP), is based on the assumption that the KS and GKS orbitals are the same. It has the form of the OAEP plus a correction term. The highest-level approximation is the density-consistent effective potential (DCEP), derived under the assumption that the KS and GKS electron densities are equal. The analytic expression for a DCEP is the OCEP formula augmented with kinetic-energy-density-dependent terms. In the case of exact-exchange functional, the OAEP is the Slater potential, the OCEP is roughly equivalent to the localized Hartree–Fock approximation and related models, and the DCEP is practically indistinguishable from the true optimized effective potential for exact exchange. All three levels of the proposed hierarchy require solutions of the GKS equations as input and have the same affordable computational cost

Size-dependent giant-magnetoresistance in millimeter scale GaAs/AlGaAs 2D electron devices

Science.gov (United States)

Mani, R. G.

2013-01-01

Large changes in the electrical resistance induced by the application of a small magnetic field are potentially useful for device-applications. Such Giant Magneto-Resistance (GMR) effects also provide new insights into the physical phenomena involved in the associated electronic transport. This study examines a “bell-shape” negative GMR that grows in magnitude with decreasing temperatures in mm-wide devices fabricated from the high-mobility GaAs/AlGaAs 2-Dimensional Electron System (2DES). Experiments show that the span of this magnetoresistance on the magnetic-field-axis increases with decreasing device width, W, while there is no concurrent Hall resistance, Rxy, correction. A multi-conduction model, including negative diagonal-conductivity, and non-vanishing off-diagonal conductivity, reproduces experimental observations. The results suggest that a size effect in the mm-wide 2DES with mm-scale electron mean-free-paths is responsible for the observed “non-ohmic” size-dependent negative GMR. PMID:24067264

Scale-dependency of the global mean surface temperature trend and its implication for the recent hiatus of global warming

Science.gov (United States)

Lin, Yong; Franzke, Christian L. E.

2015-01-01

Studies of the global mean surface temperature trend are typically conducted at a single (usually annual or decadal) time scale. The used scale does not necessarily correspond to the intrinsic scales of the natural temperature variability. This scale mismatch complicates the separation of externally forced temperature trends from natural temperature fluctuations. The hiatus of global warming since 1999 has been claimed to show that human activities play only a minor role in global warming. Most likely this claim is wrong due to the inadequate consideration of the scale-dependency in the global surface temperature (GST) evolution. Here we show that the variability and trend of the global mean surface temperature anomalies (GSTA) from January 1850 to December 2013, which incorporate both land and sea surface data, is scale-dependent and that the recent hiatus of global warming is mainly related to natural long-term oscillations. These results provide a possible explanation of the recent hiatus of global warming and suggest that the hiatus is only temporary. PMID:26259555

Inverse size scaling of the nucleolus by a concentration-dependent phase transition.

Science.gov (United States)

Weber, Stephanie C; Brangwynne, Clifford P

2015-03-02

Just as organ size typically increases with body size, the size of intracellular structures changes as cells grow and divide. Indeed, many organelles, such as the nucleus [1, 2], mitochondria [3], mitotic spindle [4, 5], and centrosome [6], exhibit size scaling, a phenomenon in which organelle size depends linearly on cell size. However, the mechanisms of organelle size scaling remain unclear. Here, we show that the size of the nucleolus, a membraneless organelle important for cell-size homeostasis [7], is coupled to cell size by an intracellular phase transition. We find that nucleolar size directly scales with cell size in early C. elegans embryos. Surprisingly, however, when embryo size is altered, we observe inverse scaling: nucleolar size increases in small cells and decreases in large cells. We demonstrate that this seemingly contradictory result arises from maternal loading of a fixed number rather than a fixed concentration of nucleolar components, which condense into nucleoli only above a threshold concentration. Our results suggest that the physics of phase transitions can dictate whether an organelle assembles, and, if so, its size, providing a mechanistic link between organelle assembly and cell size. Since the nucleolus is known to play a key role in cell growth, this biophysical readout of cell size could provide a novel feedback mechanism for growth control. Copyright © 2015 Elsevier Ltd. All rights reserved.

True and apparent scaling: The proximity of the Markov-switching multifractal model to long-range dependence

Science.gov (United States)

Liu, Ruipeng; Di Matteo, T.; Lux, Thomas

2007-09-01

In this paper, we consider daily financial data of a collection of different stock market indices, exchange rates, and interest rates, and we analyze their multi-scaling properties by estimating a simple specification of the Markov-switching multifractal (MSM) model. In order to see how well the estimated model captures the temporal dependence of the data, we estimate and compare the scaling exponents H(q) (for q=1,2) for both empirical data and simulated data of the MSM model. In most cases the multifractal model appears to generate ‘apparent’ long memory in agreement with the empirical scaling laws.

Temperature dependence of the in situ widths of a rotating condensate in one dimensional optical potential

International Nuclear Information System (INIS)

Hassan, Ahmed S.; Soliman, Shemi S.M.

2016-01-01

In this paper, a conventional method of quantum statistical mechanics is used to study the temperature dependence of the in situ widths of a rotating condensate bosons in 1D optical potential. We trace the experimentally accessible parameters for which the temperature dependence of the in situ widths becomes perceivable. The calculated results showed that the temperature dependence of the in situ widths is completely different from that of a rotating condensate or trapped bosons in the optical lattice separately. The z-width shows distinct behavior from x- and y-widths due to the rotation effect. The obtained results provide useful qualitative theoretical results for future Bose Einstein condensation experiments in such traps. - Highlights: • The temperature dependence of the in situ widths of a rotating condensate boson in 1D optical potential is investigated. • We trace the experimentally accessible parameters for which the in situ widths become perceivable. • The above mentioned parameters exhibit a characteristic rotation rate and optical potential depth dependence. • Characteristic dependence of the effective widths on temperature is investigated. • Our results provide useful qualitatively and quantitative theoretical results for experiments in various traps.

Temperature-dependent interaction potential between NF3 molecules and thermophysical properties of gaseous NF3

International Nuclear Information System (INIS)

Damyanova, M; Balabanova, E; Hohm, U

2014-01-01

A temperature-dependent effective intermolecular interaction potential is applied to describe the interaction between two nitrogen fluoride (NF 3 ) molecules in gas phase. To this end, a spherically-symmetric (n-6) Lennard-Jones temperature-dependent potential (LJTDP) is used. The (n-6) LJTDP takes into account the influence of vibrational excitation of the molecules on the potential parameters, namely, the equilibrium distance r m and the potential well depth ε. The potential parameters at T = 0 K were obtained from the very small amount of existing thermophysical equilibrium and transport properties of low-density NF 3 gas. Fitting formulae are tabulated for a fast and reliable prediction of the thermophysical properties and potential parameters in the temperature range between 200 K and 1200 K. A comparison is also presented between our estimates for some thermophysical properties of the NF 3 gas with the available experimental and calculated data.

Impact of small-scale storage systems on the photovoltaic penetration potential at the municipal scale

Science.gov (United States)

Ramirez Camargo, Luis; Dorner, Wolfgang

2016-04-01

The yearly cumulated technical energy generation potential of grid-connected roof-top photovoltaic power plants is significantly larger than the demand of domestic buildings in sparsely populated municipalities in central Europe. However, an energy balance with cumulated annual values does not deliver the right picture about the actual potential for photovoltaics since these run on a highly variable energy source as solar radiation. The mismatch between the periods of generation and demand creates hard limitations for the deployment of the theoretical energy generation potential of roof-top photovoltaics. The actual penetration of roof-top photovoltaic is restricted by the energy quality requirements of the grid and/or the available storage capacity for the electricity production beyond the coverage of own demands. In this study we evaluate in how far small-scale storage systems can contribute to increment the grid-connected roof-top photovoltaic penetration in domestic buildings at a municipal scale. To accomplish this, we calculate, in a first step, the total technical roof-top photovoltaic energy generation potential of a municipality in a high spatiotemporal resolution using a procedure that relies on geographic information systems. Posteriorly, we constrain the set of potential photovoltaic plants to the ones that would be necessary to cover the total yearly demand of the municipality. We assume that photovoltaic plants with the highest yearly yield are the ones that should be installed. For this sub-set of photovoltaic plants we consider five scenarios: 1) no storage 2) one 7 kWh battery is installed in every building with a roof-top photovoltaic plant 3) one 10 kWh battery is installed in every building with a roof-top photovoltaic plant 4) one 7 kWh battery is installed in every domestic building in the municipality 5) one 10 kWh battery is installed in every domestic building in the municipality. Afterwards we evaluate the energy balance of the

Piezoelectric and deformation potential effects of strain-dependent luminescence in semiconductor quantum well structures

DEFF Research Database (Denmark)

Zhang, Aihua; Peng, Mingzeng; Willatzen, Morten

2017-01-01

The mechanism of strain-dependent luminescence is important for the rational design of pressure-sensing devices. The interband momentum-matrix element is the key quantity for understanding luminescent phenomena. We analytically solved an infinite quantum well (IQW) model with strain, in the frame......The mechanism of strain-dependent luminescence is important for the rational design of pressure-sensing devices. The interband momentum-matrix element is the key quantity for understanding luminescent phenomena. We analytically solved an infinite quantum well (IQW) model with strain......, in the framework of the 6 × 6 k·p Hamiltonian for the valence states, to directly assess the interplay between the spin-orbit coupling and the strain-induced deformation potential for the interband momentum-matrix element. We numerically addressed problems of both the infinite and IQWs with piezoelectric fields...... to elucidate the effects of the piezoelectric potential and the deformation potential on the strain-dependent luminescence. The experimentally measured photoluminescence variatio½n as a function of pressure can be qualitatively explained by the theoretical results....

Extended consolidation of scaling laws of potential formation and effects covering the representative Tandem mirror operations in GAMMA 10

International Nuclear Information System (INIS)

Cho, T.; Higaki, H.; Hirata, M.; Hojo, H.; Ichimura, M.; Ishii, K.; Itakura, A.; Katanuma, I.; Kohagura, J.; Nakashima, Y.; Saito, T.; Tatematsu, Y.; Yoshikawa, M.; Minami, R.; Numakura, T.; Yoshida, M.; Watanabe, H.; Yatsu, K.; Miyoshi, S.; Cho, T.

2003-01-01

Scaling laws of potential formation and associated effects along with their physical interpretations are consolidated on the basis of experimental verification using the GAMMA 10 tandem mirror. A proposal of extended consolidation and generalization of the two major theories - (i) Cohen's strong electron cyclotron heating (ECH) theory for the formation physics of plasma confining potentials and (ii) the generalized Pastukhov theory for the effectiveness of the produced potentials on plasma confinement is made through the use of the energy balance equation. This proposal is then followed by verification using experimental data from two representative operational modes of GAMMA 10, characterized in terms of (i) a high-potential mode having plasma confining potentials of the order of kilovolts and (ii) a hot ion mode yielding fusion neutrons with bulk ion temperatures of 10-20 keV. The importance of the validity of the proposed physics-based scaling is highlighted by the possibility of extended capability inherent in Pastukhov's prediction of requiring an ion confining potential of ∼30 kV for a fusion Q value of unity on the basis of an application of Cohen's potential formation method. In addition to the above potential physics scaling, an externally controllable parameter scaling of the potential formation increasing with either plug or barrier ECH powers is summarized. The combination of (i) the physics-based scaling of the proposed consolidation of potential formation and effects with (ii) the externally controllable practical ECH power scaling provides a new direction for future tandem mirror studies. (author)

Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

KAUST Repository

Fiscaletti, D.

2016-10-24

The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor e(i), with the vorticity vector omega, is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors vertical bar e(i) . (omega) over cap vertical bar are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e(1), in contrast to the global tendency for omega to be aligned in parallelwith the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008)]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between omega and nonlocal e(1) and that the strongly swirling worms are kinematically significant to this process.

Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

KAUST Repository

Fiscaletti, D.; Elsinga, G. E.; Attili, Antonio; Bisetti, Fabrizio; Buxton, O. R. H.

2016-01-01

The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor e(i), with the vorticity vector omega, is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors vertical bar e(i) . (omega) over cap vertical bar are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e(1), in contrast to the global tendency for omega to be aligned in parallelwith the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008)]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between omega and nonlocal e(1) and that the strongly swirling worms are kinematically significant to this process.

Scale-dependent behavior of the foredune: Implications for barrier island response to storms and sea-level rise

Science.gov (United States)

Houser, Chris; Wernette, Phil; Weymer, Bradley A.

2018-02-01

The impact of storm surge on a barrier island tends to be considered from a single cross-shore dimension, dependent on the relative elevations of the storm surge and dune crest. However, the foredune is rarely uniform and can exhibit considerable variation in height and width at a range of length scales. In this study, LiDAR data from barrier islands in Texas and Florida are used to explore how shoreline position and dune morphology vary alongshore, and to determine how this variability is altered or reinforced by storms and post-storm recovery. Wavelet analysis reveals that a power law can approximate historical shoreline change across all scales, but that storm-scale shoreline change ( 10 years) and dune height exhibit similar scale-dependent variations at swash and surf zone scales (< 1000 m). The in-phase nature of the relationship between dune height and storm-scale shoreline change indicates that areas of greater storm-scale shoreline retreat are associated with areas of smaller dunes. It is argued that the decoupling of storm-scale and historical shoreline change at swash and surf zone scales is also associated with the alongshore redistribution of sediment and the tendency of shorelines to evolve to a more diffusive (or straight) pattern with time. The wavelet analysis of the data for post-storm dune recovery is also characterized by red noise at the smallest scales characteristic of diffusive systems, suggesting that it is possible that small-scale variations in dune height can be repaired through alongshore recovery and expansion if there is sufficient time between storms. However, the time required for dune recovery exceeds the time between storms capable of eroding and overwashing the dune. Correlation between historical shoreline retreat and the variance of the dune at swash and surf zone scales suggests that the persistence of the dune is an important control on transgression through island migration or shoreline retreat with relative sea-level rise.

Optimizing rice yields while minimizing yield-scaled global warming potential.

Science.gov (United States)

Pittelkow, Cameron M; Adviento-Borbe, Maria A; van Kessel, Chris; Hill, James E; Linquist, Bruce A

2014-05-01

To meet growing global food demand with limited land and reduced environmental impact, agricultural greenhouse gas (GHG) emissions are increasingly evaluated with respect to crop productivity, i.e., on a yield-scaled as opposed to area basis. Here, we compiled available field data on CH4 and N2 O emissions from rice production systems to test the hypothesis that in response to fertilizer nitrogen (N) addition, yield-scaled global warming potential (GWP) will be minimized at N rates that maximize yields. Within each study, yield N surplus was calculated to estimate deficit or excess N application rates with respect to the optimal N rate (defined as the N rate at which maximum yield was achieved). Relationships between yield N surplus and GHG emissions were assessed using linear and nonlinear mixed-effects models. Results indicate that yields increased in response to increasing N surplus when moving from deficit to optimal N rates. At N rates contributing to a yield N surplus, N2 O and yield-scaled N2 O emissions increased exponentially. In contrast, CH4 emissions were not impacted by N inputs. Accordingly, yield-scaled CH4 emissions decreased with N addition. Overall, yield-scaled GWP was minimized at optimal N rates, decreasing by 21% compared to treatments without N addition. These results are unique compared to aerobic cropping systems in which N2 O emissions are the primary contributor to GWP, meaning yield-scaled GWP may not necessarily decrease for aerobic crops when yields are optimized by N fertilizer addition. Balancing gains in agricultural productivity with climate change concerns, this work supports the concept that high rice yields can be achieved with minimal yield-scaled GWP through optimal N application rates. Moreover, additional improvements in N use efficiency may further reduce yield-scaled GWP, thereby strengthening the economic and environmental sustainability of rice systems. © 2013 John Wiley & Sons Ltd.

Scale and time dependence of serial correlations in word-length time series of written texts

Science.gov (United States)

Rodriguez, E.; Aguilar-Cornejo, M.; Femat, R.; Alvarez-Ramirez, J.

2014-11-01

This work considered the quantitative analysis of large written texts. To this end, the text was converted into a time series by taking the sequence of word lengths. The detrended fluctuation analysis (DFA) was used for characterizing long-range serial correlations of the time series. To this end, the DFA was implemented within a rolling window framework for estimating the variations of correlations, quantified in terms of the scaling exponent, strength along the text. Also, a filtering derivative was used to compute the dependence of the scaling exponent relative to the scale. The analysis was applied to three famous English-written literary narrations; namely, Alice in Wonderland (by Lewis Carrol), Dracula (by Bram Stoker) and Sense and Sensibility (by Jane Austen). The results showed that high correlations appear for scales of about 50-200 words, suggesting that at these scales the text contains the stronger coherence. The scaling exponent was not constant along the text, showing important variations with apparent cyclical behavior. An interesting coincidence between the scaling exponent variations and changes in narrative units (e.g., chapters) was found. This suggests that the scaling exponent obtained from the DFA is able to detect changes in narration structure as expressed by the usage of words of different lengths.

Topology Analysis of the Sloan Digital Sky Survey. I. Scale and Luminosity Dependence

Science.gov (United States)

Park, Changbom; Choi, Yun-Young; Vogeley, Michael S.; Gott, J. Richard, III; Kim, Juhan; Hikage, Chiaki; Matsubara, Takahiko; Park, Myeong-Gu; Suto, Yasushi; Weinberg, David H.; SDSS Collaboration

2005-11-01

We measure the topology of volume-limited galaxy samples selected from a parent sample of 314,050 galaxies in the Sloan Digital Sky Survey (SDSS), which is now complete enough to describe the fully three-dimensional topology and its dependence on galaxy properties. We compare the observed genus statistic G(νf) to predictions for a Gaussian random field and to the genus measured for mock surveys constructed from new large-volume simulations of the ΛCDM cosmology. In this analysis we carefully examine the dependence of the observed genus statistic on the Gaussian smoothing scale RG from 3.5 to 11 h-1 Mpc and on the luminosity of galaxies over the range -22.50meatball'' (i.e., cluster dominated) topology, while faint galaxies show a positive shift toward a ``bubble'' (i.e., void dominated) topology. The transition from negative to positive shift occurs approximately at the characteristic absolute magnitude Mr*=-20.4. Even in this analysis of the largest galaxy sample to date, we detect the influence of individual large-scale structures, as the shift parameter Δν and cluster multiplicity AC reflect (at ~3 σ) the presence of the Sloan Great Wall and an X-shaped structure that runs for several hundred megaparsecs across the survey volume.

Species and Scale Dependence of Bacterial Motion Dynamics

Science.gov (United States)

Sund, N. L.; Yang, X.; Parashar, R.; Plymale, A.; Hu, D.; Kelly, R.; Scheibe, T. D.

2017-12-01

Many metal reducing bacteria are motile with their motion characteristics described by run-and-tumble behavior exhibiting series of flights (jumps) and waiting (residence) time spanning a wide range of values. Accurate models of motility allow for improved design and evaluation of in-situ bioremediation in the subsurface. While many bioremediation models neglect the motion of the bacteria, others treat motility using an advection dispersion equation, which assumes that the motion of the bacteria is Brownian.The assumption of Brownian motion to describe motility has enormous implications on predictive capabilities of bioremediation models, yet experimental evidence of this assumption is mixed [1][2][3]. We hypothesize that this is due to the species and scale dependence of the motion dynamics. We test our hypothesis by analyzing videos of motile bacteria of five different species in open domains. Trajectories of individual cells ranging from several seconds to few minutes in duration are extracted in neutral conditions (in the absence of any chemical gradient). The density of the bacteria is kept low so that the interaction between the bacteria is minimal. Preliminary results show a transition from Fickian (Brownian) to non-Fickian behavior for one species of bacteria (Pelosinus) and persistent Fickian behavior of another species (Geobacter).Figure: Video frames of motile bacteria with the last 10 seconds of their trajectories drawn in red. (left) Pelosinus and (right) Geobacter.[1] Ariel, Gil, et al. "Swarming bacteria migrate by Lévy Walk." Nature Communications 6 (2015).[2] Saragosti, Jonathan, Pascal Silberzan, and Axel Buguin. "Modeling E. coli tumbles by rotational diffusion. Implications for chemotaxis." PloS one 7.4 (2012): e35412.[3] Wu, Mingming, et al. "Collective bacterial dynamics revealed using a three-dimensional population-scale defocused particle tracking technique." Applied and Environmental Microbiology 72.7 (2006): 4987-4994.

Potential dependence of the effective attraction in doped C60

International Nuclear Information System (INIS)

Goff, W.E.; Phillips, P.

1992-01-01

In an effort to explain superconductivity in the alkali-doped C 60 , Chakravarty and Kivelson have proposed that there is a net effective electron attraction due to intramolecular Coulomb forces. The calculation makes use of a Hubbard model in which long-range interactions are absent. The authors show that this result strongly depends on the form of the electron-electron interaction and that for potentials with long-range interactions, e.g. an Ohno potential that interpolates between an on site energy and 1/r at large distances, they do not find an effective attraction. Reasonable screening does not significantly modify this result. This indicates that the electronic mechanism in the proposed form cannot be the primary source of an attractive interaction

Global dependence of optical potential parameters for alpha particles with energies up to 80 MeV

International Nuclear Information System (INIS)

Kuterbekov, K.A.; Zholdybaev, T.K.; Sadykov, B.M.; Mukhambetzhan, A.; Kukhtina, I.N.; Penionzhkevich, Yu.Eh.

2002-01-01

Global (energy and mass) dependences of optical potential for α-particles with energies up to 80 MeV have been received. A Woods-Saxon form factor for macroscopic potential has been used. Energy and mass dependences of the semi-microscopic α-particle potential parameters have been investigated for the first time. In general, a good description of elastic and inelastic differential and total reactions cross sections for different nuclei using the revealed global parameters has been received within the framework of macroscopic and semi-microscopic approaches

[Confirmative study of a French version of the Exercise Dependence Scale-revised with a French population].

Science.gov (United States)

Allegre, B; Therme, P

2008-10-01

Since the first writings on excessive exercise, there has been an increased interest in exercise dependence. One of the major consequences of this increased interest has been the development of several definitions and measures of exercise dependence. The work of Veale [Does primary exercise dependence really exist? In: Annet J, Cripps B, Steinberg H, editors. Exercise addiction: Motivation for participation in sport and exercise.Leicester, UK: Br Psychol Soc; 1995. p. 1-5.] provides an advance for the definition and measure of exercise dependence. These studies have adapted the DSM-IV criteria for substance dependence to measure exercise dependence. The Exercise Dependence Scale-Revised is based on these diagnostic criteria, which are: tolerance; withdrawal effects; intention effect; lack of control; time; reductions in other activities; continuance. Confirmatory factor analyses of EDS-R provided support to present a measurement model (21 items loaded in seven factors) of EDS-R (Comparative Fit Index=0.97; Root mean Square Error of Approximation=0.05; Tucker-Lewis Index=0.96). The aim of this study was to examine the psychometric properties of a French version of the EDS-R [Factorial validity and psychometric examination of the exercise dependence scale-revised. Meas Phys Educ Exerc Sci 2004;8(4):183-201.] to test the stability of the seven-factor model of the original version with a French population. A total of 516 half-marathoners ranged in age from 17 to 74 years old (Mean age=39.02 years, ET=10.64), with 402 men (77.9%) and 114 women (22.1%) participated in the study. The principal component analysis results in a six-factor structure, which accounts for 68.60% of the total variance. Because principal component analysis presents a six-factor structure differing from the original seven-factor structure, two models were tested, using confirmatory factor analysis. The first model is the seven-factor model of the original version of the EDS-R and the second is the

Isospectral Trigonometric Pöschl-Teller Potentials with Position Dependent Mass Generated by Supersymmetry

International Nuclear Information System (INIS)

Santiago-Cruz, C

2016-01-01

In this work a position dependent mass Hamiltonian with the same spectrum of the trigonometric Pöschl-Teller one was constructed by means of the underlying potential algebra. The corresponding wave functions are determined by using the factorization method. A new family of isospectral potentials are constructed by applying a Darboux transformation. An example is presented in order to illustrate the formalism. (paper)

Scaling analysis of the optimized effective potentials for the multiplet states of multivalent 3d ions

International Nuclear Information System (INIS)

Hamamoto, N; Satoko, C

2006-01-01

We apply the optimized effective potential method (OPM) to the multivalent 3d n (n = 2, ..., 8) ions; M ν+ (ν = 2, ..., 8). The total energy functional is approximated by the single-configuration Hartree-Fock. The exchange potential for the average energy configuration is decomposed into the potentials derived from F 2 (3d, 3d) and F 4 (3d, 3d) Slater integrals. To investigate properties of the density-functional potential, we have checked the scaling properties of several physical quantities such as the density, the 3d orbital and these potentials. We find that the potentials of the Slater integrals do not have the scaling property. Instead, the weighted potential V i (r) of an ion i, which is the potential of the Slater integrals times the 3d-orbital density, satisfies the scaling property q 3d i V i (r) ∼ q 3d j λ 4 V j (λr) where q i 3d is the occupation number of the 3d-orbital R 3d (r) for ion i. Furthermore, the weighted potential can be approximated by the ion-independent functional of the 3d-orbital density c k R 8/3 3d (r)/q 3d where c 2 = 0.366 and c 4 0.223. This suggests that the weighted potential can be expressed as a functional of the 3d-orbital density

Scale dependence in habitat selection: The case of the endangered brown bear (Ursus arctos) in the Cantabrian Range (NW Spain)

Science.gov (United States)

Maria C. Mateo Sanchez; Samuel A. Cushman; Santiago Saura

2013-01-01

Animals select habitat resources at multiple spatial scales. Thus, explicit attention to scale dependency in species-habitat relationships is critical to understand the habitat suitability patterns as perceived by organisms in complex landscapes. Identification of the scales at which particular environmental variables influence habitat selection may be as important as...

Large-Scale Power Production Potential on U.S. Department of Energy Lands

Energy Technology Data Exchange (ETDEWEB)

Kandt, Alicen J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Elgqvist, Emma M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gagne, Douglas A. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hillesheim, Michael B. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Walker, H. A. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); King, Jeff [Colorado School of Mines, Golden, CO (United States); Boak, Jeremy [Colorado School of Mines, Golden, CO (United States); Washington, Jeremy [Colorado School of Mines, Golden, CO (United States); Sharp, Cory [Colorado School of Mines, Golden, CO (United States)

2017-11-03

This report summarizes the potential for independent power producers to generate large-scale power on U.S. Department of Energy (DOE) lands and export that power into a larger power market, rather than serving on-site DOE loads. The report focuses primarily on the analysis of renewable energy (RE) technologies that are commercially viable at utility scale, including photovoltaics (PV), concentrating solar power (CSP), wind, biomass, landfill gas (LFG), waste to energy (WTE), and geothermal technologies. The report also summarizes the availability of fossil fuel, uranium, or thorium resources at 55 DOE sites.

Manifestly scale-invariant regularization and quantum effective operators

CERN Document Server

Ghilencea, D.M.

2016-01-01

Scale invariant theories are often used to address the hierarchy problem, however the regularization of their quantum corrections introduces a dimensionful coupling (dimensional regularization) or scale (Pauli-Villars, etc) which break this symmetry explicitly. We show how to avoid this problem and study the implications of a manifestly scale invariant regularization in (classical) scale invariant theories. We use a dilaton-dependent subtraction function $\\mu(\\sigma)$ which after spontaneous breaking of scale symmetry generates the usual DR subtraction scale $\\mu(\\langle\\sigma\\rangle)$. One consequence is that "evanescent" interactions generated by scale invariance of the action in $d=4-2\\epsilon$ (but vanishing in $d=4$), give rise to new, finite quantum corrections. We find a (finite) correction $\\Delta U(\\phi,\\sigma)$ to the one-loop scalar potential for $\\phi$ and $\\sigma$, beyond the Coleman-Weinberg term. $\\Delta U$ is due to an evanescent correction ($\\propto\\epsilon$) to the field-dependent masses (of...

Zonal Articular Cartilage Possesses Complex Mechanical Behavior Spanning Multiple Length Scales: Dependence on Chemical Heterogeneity, Anisotropy, and Microstructure

Science.gov (United States)

Wahlquist, Joseph A.

This work focused on characterizing the mechanical behavior of biological material in physiologically relevant conditions and at sub millimeter length scales. Elucidating the time, length scale, and directionally dependent mechanical behavior of cartilage and other biological materials is critical to adequately recapitulate native mechanosensory cues for cells, create computational models that mimic native tissue behavior, and assess disease progression. This work focused on three broad aspects of characterizing the mechanical behavior of articular cartilage. First, we sought to reveal the causes of time-dependent deformation and variation of mechanical properties with distance from the articular surface. Second, we investigated size dependence of mechanical properties. Finally, we examined material anisotropy of both the calcified and uncalcified tissues of the osteochondral interface. This research provides insight into how articular cartilage serves to support physiologic loads and simultaneously sustain chondrocyte viability.

Observation of ion confining potential enhancement due to thermal barrier potential formation and its scaling law in the tandem mirror GAMMA 10

International Nuclear Information System (INIS)

Cho, Teruji; Nakashima, Yousuke; Foote, J.H.

1987-01-01

In the tandem mirror GAMMA 10, (i) the enhancement of the ion confining potential, φ c , only during the period of the thermal barrier potential φ b -formation, has been observed first by using not only end-loss-analysers (ELA's) of GAMMA 10 but an end-loss-ion-spectrometer (ELIS) installed from TMX-U. This results in strong end-loss-ion plugging with increased central cell density. (ii) The first experimental observation of the φ c vs φ b -scaling law is obtained, where φ c increases with φ b . This scaling law is consistently interpreted by Cohen's theories of the weak-ECH and the strong-ECH in the plug region. (iii) Good agreement of the plug potential measured with the ELA's and the ELIS is achieved. (author)

Temperature and saturation dependence in the vapor sensing of butterfly wing scales

Energy Technology Data Exchange (ETDEWEB)

Kertész, K., E-mail: kertesz.krisztian@ttk.mta.hu [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, 1525 Budapest, PO Box 49 (Hungary); Piszter, G. [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, 1525 Budapest, PO Box 49 (Hungary); Jakab, E. [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, H-1525 Budapest, P O Box 17 (Hungary); Bálint, Zs. [Hungarian Natural History Museum, H-1088, Budapest, Baross utca 13 (Hungary); Vértesy, Z.; Biró, L.P. [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, 1525 Budapest, PO Box 49 (Hungary)

2014-06-01

The sensing of gasses/vapors in the ambient air is the focus of attention due to the need to monitor our everyday environment. Photonic crystals are sensing materials of the future because of their strong light-manipulating properties. Natural photonic structures are well-suited materials for testing detection principles because they are significantly cheaper than artificial photonic structures and are available in larger sizes. Additionally, natural photonic structures may provide new ideas for developing novel artificial photonic nanoarchitectures with improved properties. In the present paper, we discuss the effects arising from the sensor temperature and the vapor concentration in air during measurements with a photonic crystal-type optical gas sensor. Our results shed light on the sources of discrepancy between simulated and experimental sensing behaviors of photonic crystal-type structures. Through capillary condensation, the vapors will condensate to a liquid state inside the nanocavities. Due to the temperature and radius of curvature dependence of capillary condensation, the measured signals are affected by the sensor temperature as well as by the presence of a nanocavity size distribution. The sensing materials used are natural photonic nanoarchitectures present in the wing scales of blue butterflies. - Highlights: • We report optical gas sensing on blue butterfly wing scale nanostructures. • The sample temperature decrease effects a reversible break-down in the measured spectra. • The break-down is connected with the vapor condensation in the scales and wing surface. • Capillary condensation occurs in the wing scales.

Temperature and saturation dependence in the vapor sensing of butterfly wing scales

International Nuclear Information System (INIS)

Kertész, K.; Piszter, G.; Jakab, E.; Bálint, Zs.; Vértesy, Z.; Biró, L.P.

2014-01-01

The sensing of gasses/vapors in the ambient air is the focus of attention due to the need to monitor our everyday environment. Photonic crystals are sensing materials of the future because of their strong light-manipulating properties. Natural photonic structures are well-suited materials for testing detection principles because they are significantly cheaper than artificial photonic structures and are available in larger sizes. Additionally, natural photonic structures may provide new ideas for developing novel artificial photonic nanoarchitectures with improved properties. In the present paper, we discuss the effects arising from the sensor temperature and the vapor concentration in air during measurements with a photonic crystal-type optical gas sensor. Our results shed light on the sources of discrepancy between simulated and experimental sensing behaviors of photonic crystal-type structures. Through capillary condensation, the vapors will condensate to a liquid state inside the nanocavities. Due to the temperature and radius of curvature dependence of capillary condensation, the measured signals are affected by the sensor temperature as well as by the presence of a nanocavity size distribution. The sensing materials used are natural photonic nanoarchitectures present in the wing scales of blue butterflies. - Highlights: • We report optical gas sensing on blue butterfly wing scale nanostructures. • The sample temperature decrease effects a reversible break-down in the measured spectra. • The break-down is connected with the vapor condensation in the scales and wing surface. • Capillary condensation occurs in the wing scales

Dependence of exponents on text length versus finite-size scaling for word-frequency distributions

Science.gov (United States)

Corral, Álvaro; Font-Clos, Francesc

2017-08-01

Some authors have recently argued that a finite-size scaling law for the text-length dependence of word-frequency distributions cannot be conceptually valid. Here we give solid quantitative evidence for the validity of this scaling law, using both careful statistical tests and analytical arguments based on the generalized central-limit theorem applied to the moments of the distribution (and obtaining a novel derivation of Heaps' law as a by-product). We also find that the picture of word-frequency distributions with power-law exponents that decrease with text length [X. Yan and P. Minnhagen, Physica A 444, 828 (2016), 10.1016/j.physa.2015.10.082] does not stand with rigorous statistical analysis. Instead, we show that the distributions are perfectly described by power-law tails with stable exponents, whose values are close to 2, in agreement with the classical Zipf's law. Some misconceptions about scaling are also clarified.

Scale-dependent performances of CMIP5 earth system models in simulating terrestrial vegetation carbon

Science.gov (United States)

Jiang, L.; Luo, Y.; Yan, Y.; Hararuk, O.

2013-12-01

Mitigation of global changes will depend on reliable projection for the future situation. As the major tools to predict future climate, Earth System Models (ESMs) used in Coupled Model Intercomparison Project Phase 5 (CMIP5) for the IPCC Fifth Assessment Report have incorporated carbon cycle components, which account for the important fluxes of carbon between the ocean, atmosphere, and terrestrial biosphere carbon reservoirs; and therefore are expected to provide more detailed and more certain projections. However, ESMs are never perfect; and evaluating the ESMs can help us to identify uncertainties in prediction and give the priorities for model development. In this study, we benchmarked carbon in live vegetation in the terrestrial ecosystems simulated by 19 ESMs models from CMIP5 with an observationally estimated data set of global carbon vegetation pool 'Olson's Major World Ecosystem Complexes Ranked by Carbon in Live Vegetation: An Updated Database Using the GLC2000 Land Cover Product' by Gibbs (2006). Our aim is to evaluate the ability of ESMs to reproduce the global vegetation carbon pool at different scales and what are the possible causes for the bias. We found that the performance CMIP5 ESMs is very scale-dependent. While CESM1-BGC, CESM1-CAM5, CESM1-FASTCHEM and CESM1-WACCM, and NorESM1-M and NorESM1-ME (they share the same model structure) have very similar global sums with the observation data but they usually perform poorly at grid cell and biome scale. In contrast, MIROC-ESM and MIROC-ESM-CHEM simulate the best on at grid cell and biome scale but have larger differences in global sums than others. Our results will help improve CMIP5 ESMs for more reliable prediction.

Investigating the dependence of SCM simulated precipitation and clouds on the spatial scale of large-scale forcing at SGP

Science.gov (United States)

Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

2017-08-01

Large-scale forcing data, such as vertical velocity and advective tendencies, are required to drive single-column models (SCMs), cloud-resolving models, and large-eddy simulations. Previous studies suggest that some errors of these model simulations could be attributed to the lack of spatial variability in the specified domain-mean large-scale forcing. This study investigates the spatial variability of the forcing and explores its impact on SCM simulated precipitation and clouds. A gridded large-scale forcing data during the March 2000 Cloud Intensive Operational Period at the Atmospheric Radiation Measurement program's Southern Great Plains site is used for analysis and to drive the single-column version of the Community Atmospheric Model Version 5 (SCAM5). When the gridded forcing data show large spatial variability, such as during a frontal passage, SCAM5 with the domain-mean forcing is not able to capture the convective systems that are partly located in the domain or that only occupy part of the domain. This problem has been largely reduced by using the gridded forcing data, which allows running SCAM5 in each subcolumn and then averaging the results within the domain. This is because the subcolumns have a better chance to capture the timing of the frontal propagation and the small-scale systems. Other potential uses of the gridded forcing data, such as understanding and testing scale-aware parameterizations, are also discussed.

Comparisons of three nicotine dependence scales in a multiethnic sample of young adult menthol and non-menthol smokers.

Science.gov (United States)

Fagan, Pebbles; Pohkrel, Pallav; Herzog, Thaddeus; Pagano, Ian; Vallone, Donna; Trinidad, Dennis R; Sakuma, Kari-Lyn; Sterling, Kymberle; Fryer, Craig S; Moolchan, Eric

2015-04-01

Few studies have compared nicotine dependence among menthol and non-menthol cigarette smokers in a multiethnic sample of young adult daily cigarette smokers. This study examines differences in nicotine dependence among menthol and non-menthol daily smokers and the associations of nicotine dependence with quitting behaviors among Native Hawaiian, Filipino, and White cigarette smokers aged 18-35. Craigslist.org, newspaper advertisements, and peer-to-peer referrals were used to recruit daily smokers (n = 186) into a lab-based study. Nicotine dependence was assessed using the Fagerstrom Test of Nicotine Dependence (FTND), the Nicotine Dependence Syndrome Scale (NDSS), and the brief Wisconsin Inventory for Smoking Dependence Motives (WISDM). Multiple regression analyses were used to examine differences in nicotine dependence between menthol and non-menthol smokers and the relationship between each nicotine dependence scale with self-efficacy to quit, quit attempt in the past 12 months, and number of attempts. Menthol smokers were more likely to report difficulty refraining from smoking in places where forbidden (p = .04) and had higher scores on social/environmental goads subscale of the WISDM (p = .0005). Two-way interaction models of the FTND and menthol status showed that menthol smokers with higher levels of dependence were more likely to have tried to quit smoking in the past 12 months (p = .02), but were less likely to have had multiple quit attempts (p = .01). Components of the FTND and WISDM distinguish levels of dependence between menthol and non-menthol smokers. Higher FTND scores were associated with having a quit attempt, but fewer quit attempts among menthol smokers. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Position-Dependent Mass Schrödinger Equation for the Morse Potential

International Nuclear Information System (INIS)

Ovando, G; Peña, J J; Morales, J; López-Bonilla, J

2017-01-01

The position dependent mass Schrödinger equation (PDMSE) has a wide range of quantum applications such as the study of semiconductors, quantum wells, quantum dots and impurities in crystals, among many others. On the other hand, the Morse potential is one of the most important potential models used to study the electronic properties of diatomic molecules. In this work, the solution of the effective mass one-dimensional Schrödinger equation for the Morse potential is presented. This is done by means of the canonical transformation method in algebraic form. The PDMSE is solved for any model of the proposed kinetic energy operators as for example the BenDaniel-Duke, Gora-Williams, Zhu-Kroemer or Li-Kuhn. Also, in order to solve the PDMSE with Morse potential, we consider a superpotential leading to a special form of the exactly solvable Schrödinger equation of constant mass for a class of multiparameter exponential-type potential along with a proper mass distribution. The proposed approach is general and can be applied in the search of new potentials suitable on science of materials by looking into the viable choices of the mass function. (paper)

Mathematical analysis of the dimensional scaling technique for the Schroedinger equation with power-law potentials

International Nuclear Information System (INIS)

Ding Zhonghai; Chen, Goong; Lin, Chang-Shou

2010-01-01

The dimensional scaling (D-scaling) technique is an innovative asymptotic expansion approach to study the multiparticle systems in molecular quantum mechanics. It enables the calculation of ground and excited state energies of quantum systems without having to solve the Schroedinger equation. In this paper, we present a mathematical analysis of the D-scaling technique for the Schroedinger equation with power-law potentials. By casting the D-scaling technique in an appropriate variational setting and studying the corresponding minimization problem, the D-scaling technique is justified rigorously. A new asymptotic dimensional expansion scheme is introduced to compute asymptotic expansions for ground state energies.

Testing feasibility of scalar-tensor gravity by scale dependent mass and coupling to matter

International Nuclear Information System (INIS)

Mota, D. F.; Salzano, V.; Capozziello, S.

2011-01-01

We investigate whether there is any cosmological evidence for a scalar field with a mass and coupling to matter which change accordingly to the properties of the astrophysical system it ''lives in,'' without directly focusing on the underlying mechanism that drives the scalar field scale-dependent-properties. We assume a Yukawa type of coupling between the field and matter and also that the scalar-field mass grows with density, in order to overcome all gravity constraints within the Solar System. We analyze three different gravitational systems assumed as ''cosmological indicators'': supernovae type Ia, low surface brightness spiral galaxies and clusters of galaxies. Results show (i) a quite good fit to the rotation curves of low surface brightness galaxies only using visible stellar and gas-mass components is obtained; (ii) a scalar field can fairly well reproduce the matter profile in clusters of galaxies, estimated by x-ray observations and without the need of any additional dark matter; and (iii) there is an intrinsic difficulty in extracting information about the possibility of a scale-dependent massive scalar field (or more generally about a varying gravitational constant) from supernovae type Ia.

Spatial heterogeneity and scale-dependent habitat selection for two sympatric raptors in mixed-grass prairie.

Science.gov (United States)

Atuo, Fidelis Akunke; O'Connell, Timothy John

2017-08-01

Sympatric predators are predicted to partition resources, especially under conditions of food limitation. Spatial heterogeneity that influences prey availability might play an important role in the scales at which potential competitors select habitat. We assessed potential mechanisms for coexistence by examining the role of heterogeneity in resource partitioning between sympatric raptors overwintering in the southern Great Plains. We conducted surveys for wintering Red-tailed hawk ( Buteo jamaicensis ) and Northern Harrier ( Circus cyanea ) at two state wildlife management areas in Oklahoma, USA. We used information from repeated distance sampling to project use locations in a GIS. We applied resource selection functions to model habitat selection at three scales and analyzed for niche partitioning using the outlying mean index. Habitat selection of the two predators was mediated by spatial heterogeneity. The two predators demonstrated significant fine-scale discrimination in habitat selection in homogeneous landscapes, but were more sympatric in heterogeneous landscapes. Red-tailed hawk used a variety of cover types in heterogeneous landscapes but specialized on riparian forest in homogeneous landscapes. Northern Harrier specialized on upland grasslands in homogeneous landscapes but selected more cover types in heterogeneous landscapes. Our study supports the growing body of evidence that landscapes can affect animal behaviors. In the system we studied, larger patches of primary land cover types were associated with greater allopatry in habitat selection between two potentially competing predators. Heterogeneity within the scale of raptor home ranges was associated with greater sympatry in use and less specialization in land cover types selected.

Temporal scale dependent interactions between multiple environmental disturbances in microcosm ecosystems.

Science.gov (United States)

Garnier, Aurélie; Pennekamp, Frank; Lemoine, Mélissa; Petchey, Owen L

2017-12-01

Global environmental change has negative impacts on ecological systems, impacting the stable provision of functions, goods, and services. Whereas effects of individual environmental changes (e.g. temperature change or change in resource availability) are reasonably well understood, we lack information about if and how multiple changes interact. We examined interactions among four types of environmental disturbance (temperature, nutrient ratio, carbon enrichment, and light) in a fully factorial design using a microbial aquatic ecosystem and observed responses of dissolved oxygen saturation at three temporal scales (resistance, resilience, and return time). We tested whether multiple disturbances combine in a dominant, additive, or interactive fashion, and compared the predictability of dissolved oxygen across scales. Carbon enrichment and shading reduced oxygen concentration in the short term (i.e. resistance); although no other effects or interactions were statistically significant, resistance decreased as the number of disturbances increased. In the medium term, only enrichment accelerated recovery, but none of the other effects (including interactions) were significant. In the long term, enrichment and shading lengthened return times, and we found significant two-way synergistic interactions between disturbances. The best performing model (dominant, additive, or interactive) depended on the temporal scale of response. In the short term (i.e. for resistance), the dominance model predicted resistance of dissolved oxygen best, due to a large effect of carbon enrichment, whereas none of the models could predict the medium term (i.e. resilience). The long-term response was best predicted by models including interactions among disturbances. Our results indicate the importance of accounting for the temporal scale of responses when researching the effects of environmental disturbances on ecosystems. © 2017 The Authors. Global Change Biology Published by John Wiley

Development of a Corrosion Potential Measuring System Based on the Generalization of DACS Physical Scale Modeling

Directory of Open Access Journals (Sweden)

Song Dalei

2015-01-01

Full Text Available A feasible method in evaluating the protection effect and corrosion state of marine cathodic protection (CP systems is collecting sufficient electric potential data around a submarine pipeline and then establishing the mapping relations between these data and corrosion states of pipelines. However, it is difficult for scientists and researchers to obtain those data accurately due to the harsh marine environments and absence of dedicated potential measurement device. In this paper, to alleviate these two problems, firstly, the theory of dimension and conductivity scaling (DACS physical scale modeling of marine impressed current cathodic protection (ICCP systems is generalized to marine CP systems, secondly, a potential measurement device is developed specially and analogue experiment is designed according to DACS physical scale modeling to verify the feasibility of the measuring system. The experimental results show that 92 percent of the measurement errors are less than 0.25mv, thereby providing an economical and feasible measuring system to get electric potential data around an actual submarine pipeline under CP.

Potential climatic impacts and reliability of large-scale offshore wind farms

International Nuclear Information System (INIS)

Wang Chien; Prinn, Ronald G

2011-01-01

The vast availability of wind power has fueled substantial interest in this renewable energy source as a potential near-zero greenhouse gas emission technology for meeting future world energy needs while addressing the climate change issue. However, in order to provide even a fraction of the estimated future energy needs, a large-scale deployment of wind turbines (several million) is required. The consequent environmental impacts, and the inherent reliability of such a large-scale usage of intermittent wind power would have to be carefully assessed, in addition to the need to lower the high current unit wind power costs. Our previous study (Wang and Prinn 2010 Atmos. Chem. Phys. 10 2053) using a three-dimensional climate model suggested that a large deployment of wind turbines over land to meet about 10% of predicted world energy needs in 2100 could lead to a significant temperature increase in the lower atmosphere over the installed regions. A global-scale perturbation to the general circulation patterns as well as to the cloud and precipitation distribution was also predicted. In the later study reported here, we conducted a set of six additional model simulations using an improved climate model to further address the potential environmental and intermittency issues of large-scale deployment of offshore wind turbines for differing installation areas and spatial densities. In contrast to the previous land installation results, the offshore wind turbine installations are found to cause a surface cooling over the installed offshore regions. This cooling is due principally to the enhanced latent heat flux from the sea surface to lower atmosphere, driven by an increase in turbulent mixing caused by the wind turbines which was not entirely offset by the concurrent reduction of mean wind kinetic energy. We found that the perturbation of the large-scale deployment of offshore wind turbines to the global climate is relatively small compared to the case of land

Interplay of infrared divergences and gauge-dependence of the effective potential

International Nuclear Information System (INIS)

Espinosa, J.R.; Garny, M.; Konstandin, T.

2016-07-01

The perturbative effective potential suffers infrared (IR) divergences in gauges with massless Goldstones in their minima (like Landau or Fermi gauges) but the problem can be fixed by a suitable resummation of the Goldstone propagators. When the potential minimum is generated radiatively, gauge-independence of the potential at the minimum also requires resummation and we demonstrate that the resummation that solves the IR problem also cures the gauge-dependence issue, showing this explicitly in the Abelian Higgs model in Fermi gauge. In the process we find an IR divergence (in the location of the minimum) specific to Fermi gauge and not appreciated in recent literature. We show that physical observables can still be computed in this gauge and we further show how to get rid of this divergence by a field redefinition. All these results generalize to the Standard Model case.

Interplay of Infrared Divergences and Gauge-Dependence of the Effective Potential

CERN Document Server

Espinosa, J.R.; Konstandin, T.

2016-01-01

The perturbative effective potential suffers infrared (IR) divergences in gauges with massless Goldstones in their minima (like Landau or Fermi gauges) but the problem can be fixed by a suitable resummation of the Goldstone propagators. When the potential minimum is generated radiatively, gauge-independence of the potential at the minimum also requires resummation and we demonstrate that the resummation that solves the IR problem also cures the gauge-dependence issue, showing this explicitly in the Abelian Higgs model in Fermi gauge. In the process we find an IR divergence (in the location of the minimum) specific to Fermi gauge and not appreciated in recent literature. We show that physical observables can still be computed in this gauge and we further show how to get rid of this divergence by a field redefinition. All these results generalize to the Standard Model case.

POTENTIAL OF BUSINESS

OpenAIRE

Julija Avakumovic, Jelena Avakumovic

2014-01-01

Potential of businesses is available and relevant developed business opportunities which under certain conditions can affect the results of the business. Those are certain conditions possible exposure of the company. The success of a business depends of the knowledge of these resources and the way how to find the optimum combination of scale, structure and dynamics of available resources by the management of the business.

Potential vorticity dynamics for global scale circulations

International Nuclear Information System (INIS)

Lu, C.; Schubert, W.

1994-01-01

One of the most notable advances in extratropical dynamics this decade has been the understanding of large-scale atmospheric and oceanic processes by using potential vorticity dynamics, the so called open-quotes IPV thinking.close quotes This analysis method has also been successfully extended to some tropical atmospheric circulation systems such as hurricanes and the Hadley circulation. The fundamental idea behind such a dynamic system rests with the fact that PV is a tracer-like quantity since it is conserved (in the absence of friction and diabatic heating) following a fluid particle and carries both significant dynamic and thermodynamic information regarding fluid motion. Thus, the prediction and inversion of PV form the most succinct dynamic view of atmospheric and oceanic motions. Furthermore, PV dynamics provides access to many insightful dynamic analyses such as: Propagation of Rossby waves, barotropic and baroclinic instabilities for shear flows, and wave-mean flow interactions. All these features make IPV analysis a very attractive tool for studying geophysical fluid systems

COLA with scale-dependent growth: applications to screened modified gravity models

Energy Technology Data Exchange (ETDEWEB)

Winther, Hans A.; Koyama, Kazuya; Wright, Bill S. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); Manera, Marc [Centre for Theoretical Cosmology, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Zhao, Gong-Bo, E-mail: hans.a.winther@gmail.com, E-mail: kazuya.koyama@port.ac.uk, E-mail: manera.work@gmail.com, E-mail: bill.wright@port.ac.uk, E-mail: gong-bo.Zhao@port.ac.uk [National Astronomy Observatories, Chinese Academy of Science, Beijing, 100012 (China)

2017-08-01

We present a general parallelized and easy-to-use code to perform numerical simulations of structure formation using the COLA (COmoving Lagrangian Acceleration) method for cosmological models that exhibit scale-dependent growth at the level of first and second order Lagrangian perturbation theory. For modified gravity theories we also include screening using a fast approximate method that covers all the main examples of screening mechanisms in the literature. We test the code by comparing it to full simulations of two popular modified gravity models, namely f ( R ) gravity and nDGP, and find good agreement in the modified gravity boost-factors relative to ΛCDM even when using a fairly small number of COLA time steps.

Dependency of high coastal water level and river discharge at the global scale

Science.gov (United States)

Ward, P.; Couasnon, A.; Haigh, I. D.; Muis, S.; Veldkamp, T.; Winsemius, H.; Wahl, T.

2017-12-01

It is widely recognized that floods cause huge socioeconomic impacts. From 1980-2013, global flood losses exceeded $1 trillion, with 220,000 fatalities. These impacts are particularly hard felt in low-lying densely populated deltas and estuaries, whose location at the coast-land interface makes them naturally prone to flooding. When river and coastal floods coincide, their impacts in these deltas and estuaries are often worse than when they occur in isolation. Such floods are examples of so-called `compound events'. In this contribution, we present the first global scale analysis of the statistical dependency of high coastal water levels (and the storm surge component alone) and river discharge. We show that there is statistical dependency between these components at more than half of the stations examined. We also show time-lags in the highest correlation between peak discharges and coastal water levels. Finally, we assess the probability of the simultaneous occurrence of design discharge and design coastal water levels, assuming both independence and statistical dependence. For those stations where we identified statistical dependency, the probability is between 1 and 5 times greater, when the dependence structure is accounted for. This information is essential for understanding the likelihood of compound flood events occurring at locations around the world as well as for accurate flood risk assessments and effective flood risk management. The research was carried out by analysing the statistical dependency between observed coastal water levels (and the storm surge component) from GESLA-2 and river discharge using gauged data from GRDC stations all around the world. The dependence structure was examined using copula functions.

Power law scaling in synchronization of brain signals depends on cognitive load

Directory of Open Access Journals (Sweden)

Jose Luis ePerez Velazquez

2014-05-01

Full Text Available As it has several features that optimize information processing, it has been proposed that criticality governs the dynamics of nervous system activity. Indications of such dynamics have been reported for a variety of in vitro and in vivo recordings, ranging from in vitro slice electrophysiology to human functional magnetic resonance imaging. However, there still remains considerable debate as to whether the brain actually operates close to criticality or in another governing state such as stochastic or oscillatory dynamics. A tool used to investigate the criticality of nervous system data is the inspection of power-law distributions. Although the findings are controversial, such power-law scaling has been found in different types of recordings. Here, we studied whether there is a power law scaling in the distribution of the phase synchronization derived from magnetoencephalographic recordings during executive function tasks performed by children with and without autism. Characterizing the brain dynamics that is different between autistic and non-autistic individuals is important in order to find differences that could either aid diagnosis or provide insights as to possible therapeutic interventions in autism. We report in this study that power law scaling in the distributions of a phase synchrony index is not very common and its frequency of occurrence is similar in the control and the autism group. In addition, power law scaling tends to diminish with increased cognitive load (difficulty or engagement in the task. There were indications of changes in the probability distribution functions for the phase synchrony that were associated with a transition from power law scaling to lack of power law (or vice versa, which suggests the presence of phenomenological bifurcations in brain dynamics associated with cognitive load. Hence, brain dynamics may fluctuate between criticality and other regimes depending upon context and behaviours.

Betel-quid dependence and oral potentially malignant disorders in six Asian countries.

Science.gov (United States)

Lee, Chien-Hung; Ko, Albert Min-Shan; Yen, Cheng-Fang; Chu, Koung-Shing; Gao, Yi-Jun; Warnakulasuriya, Saman; Sunarjo; Ibrahim, Salah Osman; Zain, Rosnah Binti; Patrick, Walter K; Ko, Ying-Chin

2012-11-01

Despite gradual understanding of the multidimensional health consequences of betel-quid chewing, information on the effects of dependent use is scant. To investigate the 12-month prevalence patterns of betel-quid dependence in six Asian populations and the impact of this dependence on oral potentially malignant disorders (OPMD). A multistage random sample of 8922 participants was recruited from Taiwan, mainland China, Indonesia, Malaysia, Sri Lanka and Nepal. Participants were evaluated for betel-quid dependency using DSM-IV and ICD-10 criteria and assessed clinically for oral mucosal lesions. The 12-month prevalence of dependence was 2.8-39.2% across the six Asian samples, and 20.9-99.6% of those who chewed betel-quid were betel-quid dependent. Men dominated the prevalence among the east Asian samples and women dominated the prevalence in south-east Asian samples. 'Time spent chewing' and 'craving' were the central dependence domains endorsed by the Chinese and southern/south-east Asian samples respectively, whereas the Nepalese samples endorsed 'tolerance' and 'withdrawal'. Dependency was linked to age, gender, schooling years, drinking, smoking, tobacco-added betel-quid use and environmental accessibility of betel-quid. Compared with non-users, those with betel-quid dependency had higher pre-neoplastic risks (adjusted odds ratios 8.0-51.3) than people with non-dependent betel-quid use (adjusted odds ratio 4.5-5.9) in the six Asian populations. By elucidating differences in domain-level symptoms of betel-quid dependency and individual and environmental factors, this study draws attention to the population-level psychiatric problems of betel-quid chewing that undermine health consequences for OPMD in six Asian communities.

Fractal and multifractal approaches for the analysis of crack-size dependent scaling laws in fatigue

Energy Technology Data Exchange (ETDEWEB)

Paggi, Marco [Politecnico di Torino, Department of Structural Engineering and Geotechnics, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)], E-mail: marco.paggi@polito.it; Carpinteri, Alberto [Politecnico di Torino, Department of Structural Engineering and Geotechnics, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

2009-05-15

The enhanced ability to detect and measure very short cracks, along with a great interest in applying fracture mechanics formulae to smaller and smaller crack sizes, has pointed out the so-called anomalous behavior of short cracks with respect to their longer counterparts. The crack-size dependencies of both the fatigue threshold and the Paris' constant C are only two notable examples of these anomalous scaling laws. In this framework, a unified theoretical model seems to be missing and the behavior of short cracks can still be considered as an open problem. In this paper, we propose a critical reexamination of the fractal models for the analysis of crack-size effects in fatigue. The limitations of each model are put into evidence and removed. At the end, a new generalized theory based on fractal geometry is proposed, which permits to consistently interpret the short crack-related anomalous scaling laws within a unified theoretical formulation. Finally, this approach is herein used to interpret relevant experimental data related to the crack-size dependence of the fatigue threshold in metals.

Fractal and multifractal approaches for the analysis of crack-size dependent scaling laws in fatigue

International Nuclear Information System (INIS)

Paggi, Marco; Carpinteri, Alberto

2009-01-01

The enhanced ability to detect and measure very short cracks, along with a great interest in applying fracture mechanics formulae to smaller and smaller crack sizes, has pointed out the so-called anomalous behavior of short cracks with respect to their longer counterparts. The crack-size dependencies of both the fatigue threshold and the Paris' constant C are only two notable examples of these anomalous scaling laws. In this framework, a unified theoretical model seems to be missing and the behavior of short cracks can still be considered as an open problem. In this paper, we propose a critical reexamination of the fractal models for the analysis of crack-size effects in fatigue. The limitations of each model are put into evidence and removed. At the end, a new generalized theory based on fractal geometry is proposed, which permits to consistently interpret the short crack-related anomalous scaling laws within a unified theoretical formulation. Finally, this approach is herein used to interpret relevant experimental data related to the crack-size dependence of the fatigue threshold in metals.

Utilizing Monte-Carlo radiation transport and spallation cross sections to estimate nuclide dependent scaling with altitude

Science.gov (United States)

Argento, D.; Reedy, R. C.; Stone, J.

2010-12-01

Cosmogenic Nuclides (CNs) are a critical new tool for geomorphology, allowing researchers to date Earth surface events and measure process rates [1]. Prior to CNs, many of these events and processes had no absolute method for measurement and relied entirely on relative methods [2]. Continued improvements in CN methods are necessary for expanding analytic capability in geomorphology. In the last two decades, significant progress has been made in refining these methods and reducing analytic uncertainties [1,3]. Calibration data and scaling methods are being developed to provide a self consistent platform for use in interpreting nuclide concentration values into geologic data [4]. However, nuclide dependent scaling has been difficult to address due to analytic uncertainty and sparseness in altitude transects. Artificial target experiments are underway, but these experiments take considerable time for nuclide buildup in lower altitudes. In this study, a Monte Carlo method radiation transport code, MCNPX, is used to model the galactic cosmic-ray radiation impinging on the upper atmosphere and track the resulting secondary particles through a model of the Earth’s atmosphere and lithosphere. To address the issue of nuclide dependent scaling, the neutron flux values determined by the MCNPX simulation are folded in with estimated cross-section values [5,6]. Preliminary calculations indicate that scaling of nuclide production potential in free air seems to be a function of both altitude and nuclide production pathway. At 0 g/cm2 (sea-level) all neutron spallation pathways have attenuation lengths within 1% of 130 g/cm2. However, the differences in attenuation length are exacerbated with increasing altitude. At 530 g/cm2 atmospheric height (~5,500 m), the apparent attenuation lengths for aggregate SiO2(n,x)10Be, aggregate SiO2(n,x)14C and K(n,x)36Cl become 149.5 g/cm2, 151 g/cm2 and 148 g/cm2 respectively. At 700 g/cm2 atmospheric height (~8,400m - close to the highest

Residual strain, scale effects, and time-dependent behaviour at the 240-m level of the underground research laboratory

International Nuclear Information System (INIS)

Read, R.S.

1990-01-01

Two subhorizontal, orthogonal boreholes were monitored continuously during concentric overcoring at the 240-m level of the Underground Research Laboratory (URL). The magnitude and orientation of principal residual strain components in the near-field stress regime were determined assuming linear elastic behaviour of the rock mass and isotropic conditions. In terms of magnitude, results compared favourably with those from previous tests at the 240-m level. However, orientation results were inconclusive. The effects of scale and borehole orientation relative to the principal stress direction on the results from a modified CSIR triaxial cell overcore test were also investigated; no scale effects were apparent in the experiment, but borehole orientation did affect results. Finally, time-dependent behaviour was detected in the Lac du Bonnet granite, and was monitored between successive overcore tests in one of the boreholes. Results on residual strain, scale effects, and time-dependent behaviour are presented, along with limitations and possible modifications to the testing procedure

From interatomic interaction potentials via Einstein field equation techniques to time dependent contact mechanics

International Nuclear Information System (INIS)

Schwarzer, N

2014-01-01

In order to understand the principle differences between rheological or simple stress tests like the uniaxial tensile test to contact mechanical tests and the differences between quasistatic contact experiments and oscillatory ones, this study resorts to effective first principles. This study will show how relatively simple models simulating bond interactions in solids using effective potentials like Lennard-Jones and Morse can be used to investigate the effect of time dependent stress-induced softening or stiffening of these solids. The usefulness of the current study is in the possibility of deriving relatively simple dependences of the bulk-modulus B on time, shear and pressure P with time t. In cases where it is possible to describe, or at least partially describe a material by Lennard-Jones potential approaches, the above- mentioned dependences are even completely free of microscopic material parameters. Instead of bond energies and length, only specific integral parameters like Young’s modulus and Poisson’s ratio are required. However, in the case of time dependent (viscose) material behavior the parameters are not constants anymore. They themselves depend on time and the actual stress field, especially the shear field. A body completely consisting of so called standard linear solid interacting particles will then phenomenologically show a completely different and usually much more complicated mechanical behavior. The influence of the time dependent pressure-shear-induced Young’s modulus change is discussed with respect to mechanical contact experiments and their analysis in the case of viscose materials. (papers)

Exact invariants in the form of momentum resonances for particle motion in one-dimensional, time-dependent potentials

International Nuclear Information System (INIS)

Goedert, J.; Lewis, H.R.

1984-01-01

A momentum-resonance ansatz of Lewis and Leach was used to study exact invariants for time-dependent, one-dimensional potentials. This ansatz provides a framework for finding invariants admitted by a larger class of time-dependent potentials that was known previously. For a potential that admits an exact invariant in this resonance form, we have shown how to construct the invariant as a functional of the potential in terms of the solution of a definite linear algebraic system of equations. We have found a necessary and sufficient condition on the potential for the existence of an invariant with a given number of resonances. There exist more potentials that admit invariants with two resonances than were previously known and we have found an example in parametric form of such a potential. We have also found examples of potentials that admit invariants with three resonances

Chameleons with Field Dependent Couplings

CERN Document Server

Brax, Philippe; Mota, David F; Nunes, Nelson J; Winther, Hans A

2010-01-01

Certain scalar-tensor theories exhibit the so-called chameleon mechanism, whereby observational signatures of scalar fields are hidden by a combination of self-interactions and interactions with ambient matter. Not all scalar-tensor theories exhibit such a chameleon mechanism, which has been originally found in models with inverse power run-away potentials and field independent couplings to matter. In this paper we investigate field-theories with field-dependent couplings and a power-law potential for the scalar field. We show that the theory indeed is a chameleon field theory. We find the thin-shell solution for a spherical body and investigate the consequences for E\\"ot-Wash experiments, fifth-force searches and Casimir force experiments. Requiring that the scalar-field evades gravitational tests, we find that the coupling is sensitive to a mass-scale which is of order of the Hubble scale today.

Chameleons with field-dependent couplings

International Nuclear Information System (INIS)

Brax, Philippe; Bruck, Carsten van de; Mota, David F.; Winther, Hans A.; Nunes, Nelson J.

2010-01-01

Certain scalar-tensor theories exhibit the so-called chameleon mechanism, whereby observational signatures of scalar fields are hidden by a combination of self-interactions and interactions with ambient matter. Not all scalar-tensor theories exhibit such a chameleon mechanism, which has been originally found in models with inverse power runaway potentials and field-independent couplings to matter. In this paper we investigate field theories with field-dependent couplings and a power-law potential for the scalar field. We show that the theory indeed is a chameleon field theory. We find the thin-shell solution for a spherical body and investigate the consequences for Eoet-Wash experiments, fifth-force searches and Casimir-force experiments. Requiring that the scalar field evades gravitational tests, we find that the coupling is sensitive to a mass scale which is of order of the Hubble scale today.

Accelerating electrostatic surface potential calculation with multi-scale approximation on graphics processing units.

Science.gov (United States)

Anandakrishnan, Ramu; Scogland, Tom R W; Fenley, Andrew T; Gordon, John C; Feng, Wu-chun; Onufriev, Alexey V

2010-06-01

Tools that compute and visualize biomolecular electrostatic surface potential have been used extensively for studying biomolecular function. However, determining the surface potential for large biomolecules on a typical desktop computer can take days or longer using currently available tools and methods. Two commonly used techniques to speed-up these types of electrostatic computations are approximations based on multi-scale coarse-graining and parallelization across multiple processors. This paper demonstrates that for the computation of electrostatic surface potential, these two techniques can be combined to deliver significantly greater speed-up than either one separately, something that is in general not always possible. Specifically, the electrostatic potential computation, using an analytical linearized Poisson-Boltzmann (ALPB) method, is approximated using the hierarchical charge partitioning (HCP) multi-scale method, and parallelized on an ATI Radeon 4870 graphical processing unit (GPU). The implementation delivers a combined 934-fold speed-up for a 476,040 atom viral capsid, compared to an equivalent non-parallel implementation on an Intel E6550 CPU without the approximation. This speed-up is significantly greater than the 42-fold speed-up for the HCP approximation alone or the 182-fold speed-up for the GPU alone. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Local chemical potential, local hardness, and dual descriptors in temperature dependent chemical reactivity theory.

Science.gov (United States)

Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

2017-05-31

In this work we establish a new temperature dependent procedure within the grand canonical ensemble, to avoid the Dirac delta function exhibited by some of the second order chemical reactivity descriptors based on density functional theory, at a temperature of 0 K. Through the definition of a local chemical potential designed to integrate to the global temperature dependent electronic chemical potential, the local chemical hardness is expressed in terms of the derivative of this local chemical potential with respect to the average number of electrons. For the three-ground-states ensemble model, this local hardness contains a term that is equal to the one intuitively proposed by Meneses, Tiznado, Contreras and Fuentealba, which integrates to the global hardness given by the difference in the first ionization potential, I, and the electron affinity, A, at any temperature. However, in the present approach one finds an additional temperature-dependent term that introduces changes at the local level and integrates to zero. Additionally, a τ-hard dual descriptor and a τ-soft dual descriptor given in terms of the product of the global hardness and the global softness multiplied by the dual descriptor, respectively, are derived. Since all these reactivity indices are given by expressions composed of terms that correspond to products of the global properties multiplied by the electrophilic or nucleophilic Fukui functions, they may be useful for studying and comparing equivalent sites in different chemical environments.

The effect of urban growth on landscape-scale restoration for a fire-dependent songbird

Science.gov (United States)

Pickens, Bradley A.; Marcus, Jeffrey F.; Carpenter, John P.; Anderson, Scott; Taillie, Paul J.; Collazo, Jaime A.

2017-01-01

A landscape-scale perspective on restoration ecology has been advocated, but few studies have informed restoration with landscape metrics or addressed broad-scale threats. Threats such as urban growth may affect restoration effectiveness in a landscape context. Here, we studied longleaf pine savanna in the rapidly urbanizing southeastern United States where a habitat-specialist bird, Bachman's sparrow (Peucaea aestivalis), is closely associated with savanna vegetation structure and frequent fire. Our objectives were to construct a species distribution model for Bachman's sparrow, determine the relationship between fire and urbanization, quantify the urban growth effect (2010–2090), identify potential restoration areas, and determine the interaction between restoration potential and urban growth by 2050. Number of patches, patch size, and isolation metrics were used to evaluate scenarios. The species distribution model was 88% accurate and emphasized multiscale canopy cover characteristics, fire, and percent habitat. Fires were less common urban areas, and this fire suppression effect exacerbated urban growth effects. For restoration scenarios, canopy cover reduction by 30% resulted in nearly double the amount of habitat compared to the prescribed fire scenario; canopy cover reduction resulted in larger patch sizes and less patch isolation compared to current conditions. The effect of urban growth on restoration scenarios was unequal. Seventy-four percent of restoration areas from the prescribed fire scenario overlapped with projected urban growth, whereas the canopy cover reduction scenario only overlapped by 9%. We emphasize the benefits of simultaneously considering the effects of urban growth and landscape-scale restoration potential to promote a landscape with greater patch sizes and less isolation.

SFG study on potential-dependent structure of water at Pt electrode/electrolyte solution interface

Energy Technology Data Exchange (ETDEWEB)

Noguchi, Hidenori; Okada, Tsubasa; Uosaki, Kohei [Physical Chemistry Laboratory, Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan)

2008-10-01

Structure of water at Pt/electrolyte solution interface was investigated by sum frequency generation (SFG) spectroscopy. Two broad peaks were observed in OH stretching region at ca. 3200 cm{sup -1} and ca. 3400 cm{sup -1}, which are known to be due to the symmetric OH stretching (U{sub 1}) of tetrahedrally coordinated, i.e., strongly hydrogen bonded 'ice-like' water, and the asymmetric OH stretching (U{sub 3}) of water molecules in a more random arrangement, i.e., weakly hydrogen bonded 'liquid-like' water, respectively. The SFG intensity strongly depended on electrode potential. Several possibilities are suggested for the potential dependence of the SFG intensity. (author)

Chemical Potential Dependence of the Dressed-Quark Propagator from an Effective Quark-Quark Interaction

Institute of Scientific and Technical Information of China (English)

ZONG Hong-Shi; PING Jia-Lun; SUN Wei-Min; CHANG Chao-Hsi; WANG Fan

2002-01-01

We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagatorfrom an effective quark-quark interaction model. Within this approach we explore the chemical potential dependenceof the dressed-quark propagator, which provides a means of determining the behavior of the chiral and deconfinementorder parameters. A comparison with the results of previous researches is given.

Dependability and Treatment Sensitivity of Multi-Item Direct Behavior Rating Scales for Interpersonal Peer Conflict

Science.gov (United States)

Daniels, Brian; Volpe, Robert J.; Briesch, Amy M.; Gadow, Kenneth D.

2017-01-01

Direct behavior rating (DBR) represents a feasible method for monitoring student behavior in the classroom; however, limited work to date has focused on the use of multi-item scales. The purposes of the study were to examine the (a) dependability of data obtained from a multi-item DBR designed to assess peer conflict and (b) treatment sensitivity…

Reliability, validity, and interpretation of the dependence scale in mild to moderately severe Alzheimer's disease.

Science.gov (United States)

Lenderking, William R; Wyrwich, Kathleen W; Stolar, Marilyn; Howard, Kellee A; Leibman, Chris; Buchanan, Jacqui; Lacey, Loretto; Kopp, Zoe; Stern, Yaakov

2013-12-01

The Dependence Scale (DS) was designed to measure dependence on others among patients with Alzheimer's disease (AD). The objectives of this research were primarily to strengthen the psychometric evidence for the use of the DS in AD studies. Patients with mild to moderately severe AD were examined in 3 study databases. Within each data set, internal consistency, validity, and responsiveness were examined, and structural equation models were fit. The DS has strong psychometric properties. The DS scores differed significantly across known groups and demonstrated moderate to strong correlations with measures hypothesized to be related to dependence (|r| ≥ .31). Structural equation modeling supported the validity of the DS concept. An anchor-based DS responder definition to interpret a treatment benefit over time was identified. The DS is a reliable, valid, and interpretable measure of dependence associated with AD and is shown to be related to--but provides information distinct from--cognition, functioning, and behavior.

Performance of small-scale photovoltaic systems and their potential for rural electrification in Ethiopia

Energy Technology Data Exchange (ETDEWEB)

Stutenbaeumer, Ulrich; Negash, Tesfaye; Abdi, Amensisa [Addis Ababa Univ., Dept. of Physics, Addis Ababa (Ethiopia)

1999-09-01

The performance of small-scale stand-alone photovoltaic systems is tested under the climatic conditions of Addis Ababa, Ethiopia. With climatic data obtained at a station in the Rift Valley, the photovoltaic systems performance is estimated for those climatic conditions. The economics of small-scale stand-alone photovoltaic system applications under Ethiopian conditions are analysed. The potential of photovoltaics for the rural electrification of Ethiopia is discussed. (Author)

Comparing Existing Pipeline Networks with the Potential Scale of Future U.S. CO2 Pipeline Networks

Energy Technology Data Exchange (ETDEWEB)

Dooley, James J.; Dahowski, Robert T.; Davidson, Casie L.

2008-02-29

There is growing interest regarding the potential size of a future U.S. dedicated CO2 pipeline infrastructure if carbon dioxide capture and storage (CCS) technologies are commercially deployed on a large scale. In trying to understand the potential scale of a future national CO2 pipeline network, comparisons are often made to the existing pipeline networks used to deliver natural gas and liquid hydrocarbons to markets within the U.S. This paper assesses the potential scale of the CO2 pipeline system needed under two hypothetical climate policies and compares this to the extant U.S. pipeline infrastructures used to deliver CO2 for enhanced oil recovery (EOR), and to move natural gas and liquid hydrocarbons from areas of production and importation to markets. The data presented here suggest that the need to increase the size of the existing dedicated CO2 pipeline system should not be seen as a significant obstacle for the commercial deployment of CCS technologies.

Impaired Na⁺-dependent regulation of acetylcholine-activated inward-rectifier K⁺ current modulates action potential rate dependence in patients with chronic atrial fibrillation.

Science.gov (United States)

Voigt, Niels; Heijman, Jordi; Trausch, Anne; Mintert-Jancke, Elisa; Pott, Lutz; Ravens, Ursula; Dobrev, Dobromir

2013-08-01

Shortened action-potential duration (APD) and blunted APD rate adaptation are hallmarks of chronic atrial fibrillation (cAF). Basal and muscarinic (M)-receptor-activated inward-rectifier K(+) currents (IK1 and IK,ACh, respectively) contribute to regulation of human atrial APD and are subject to cAF-dependent remodeling. Intracellular Na(+) ([Na(+)]i) enhances IK,ACh in experimental models but the effect of [Na(+)]i-dependent regulation of inward-rectifier K(+) currents on APD in human atrial myocytes is currently unknown. Here, we report a [Na(+)]i-dependent inhibition of outward IK1 in atrial myocytes from sinus rhythm (SR) or cAF patients. In contrast, IK,ACh activated by carbachol, a non-selective M-receptor agonist, increased with elevation of [Na(+)]i in SR. This [Na(+)]i-dependent IK,ACh regulation was absent in cAF. Including [Na(+)]i dependence of IK1 and IK,ACh in a recent computational model of the human atrial myocyte revealed that [Na(+)]i accumulation at fast rates inhibits IK1 and blunts physiological APD rate dependence in both groups. [Na(+)]i-dependent IK,ACh augmentation at fast rates increased APD rate dependence in SR, but not in cAF. These results identify impaired Na(+)-sensitivity of IK,ACh as one potential mechanism contributing to the blunted APD rate dependence in patients with cAF. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes". Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

Urban Freight Management with Stochastic Time-Dependent Travel Times and Application to Large-Scale Transportation Networks

Directory of Open Access Journals (Sweden)

Shichao Sun

2015-01-01

Full Text Available This paper addressed the vehicle routing problem (VRP in large-scale urban transportation networks with stochastic time-dependent (STD travel times. The subproblem which is how to find the optimal path connecting any pair of customer nodes in a STD network was solved through a robust approach without requiring the probability distributions of link travel times. Based on that, the proposed STD-VRP model can be converted into solving a normal time-dependent VRP (TD-VRP, and algorithms for such TD-VRPs can also be introduced to obtain the solution. Numerical experiments were conducted to address STD-VRPTW of practical sizes on a real world urban network, demonstrated here on the road network of Shenzhen, China. The stochastic time-dependent link travel times of the network were calibrated by historical floating car data. A route construction algorithm was applied to solve the STD problem in 4 delivery scenarios efficiently. The computational results showed that the proposed STD-VRPTW model can improve the level of customer service by satisfying the time-window constraint under any circumstances. The improvement can be very significant especially for large-scale network delivery tasks with no more increase in cost and environmental impacts.

Motivation for treatment in substance-dependent patients. Psychometric evaluation of the TCU motivation for treatment scales

NARCIS (Netherlands)

de Weert-van Oene, Gerdien H.; Schippers, Gerard M.; de Jong, Cor A. J.; Schrijvers, Guus A. J. P.

2002-01-01

The objective of this paper is to analyze the psychometric properties of the TCU Motivation for Treatment (MfT) scale in alcohol- and drug-dependent patients in an inpatient treatment facility in the Netherlands, to see whether it is useful in European populations as well. In the study, 279

Calcium-dependent plateau potentials in rostral ambiguus neurons in the newborn mouse brain stem in vitro

DEFF Research Database (Denmark)

Rekling, J C; Feldman, J L

1997-01-01

Calcium-dependent plateau potentials in rostral ambiguus neurons in the newborn mouse brain stem in vitro. J. Neurophysiol. 78: 2483-2492, 1997. The nucleus ambiguus contains vagal and glossopharyngeal motoneurons and preganglionic neurons involved in respiration, swallowing, vocalization......-stimulus orthodromic activation, using an electrode placed in the dorsomedial slice near the nucleus tractus solitarius, evoked single excitatory postsynaptic potentials (EPSPs) or short trains of EPSPs (500 ms to 1 s). However, tetanic stimulation (5 pulses, 10 Hz) induced voltage-dependent afterdepolarizations...

Sediment budgets of mountain catchments: Scale dependence and the influence of land-use

Science.gov (United States)

Förster, Helga; Dotterweich, Markus; Wunderlich, Jürgen

2010-05-01

Long-term sediment budgets of forested mountain catchments are scarcely investigated today. This is because they are traditionally expected to show few erosion features and low sediment delivery. This opinion originates from process-based hydrological studies proving the runoff preventing properties of trees and forest soils. In addition mountain areas have been colonized later and only sporadically compared to the fruitful loess-covered lowlands. On the other hand steep hillslopes, narrow valleys and the availability of regolith cause a high erosion potential. And there is evidence that historical floods and yearly occurring storms initiate intensive but local and sporadic erosion events. Sediment budgets from zero-order catchments of the Palatinate Forest in the south-western sandstone escarpment in Rhineland-Palatinate show spatially varying intensities of land use impact and relief conditions. The budgets are based on field data and a soilscape model of an upper periglacial cover bed with a homogenous thickness. OSL- and 14C-dates of colluvial deposits allow relating erosion events to land-use changes derived from historical maps and written archives. The presented case studies from the Palatinate Forest are of special interest as the high proximity to the loess-covered and intensively cultivated Rhine Graben effected settlement and land-use intensity in the mountain catchments. Clear cuts for settlements were joined by deforestation for agriculture and stretched mainly along the Haardtrand and high order valleys. Off these areas the strength of interference in the forest ecosystem depended on transport possibilities and distance to the Rhine Graben. In the vicinity strong devastation and clear cutting occurred. With increasing distance the felling intensity decreased and some parts seem to be nearly undisturbed until the 18th century. The needs for wood were controlled by the economical development as well as political decisions on local to European scale. The

Scale-Dependence of Processes Structuring Dung Beetle Metacommunities Using Functional Diversity and Community Deconstruction Approaches

Science.gov (United States)

da Silva, Pedro Giovâni; Hernández, Malva Isabel Medina

2015-01-01

Community structure is driven by mechanisms linked to environmental, spatial and temporal processes, which have been successfully addressed using metacommunity framework. The relative importance of processes shaping community structure can be identified using several different approaches. Two approaches that are increasingly being used are functional diversity and community deconstruction. Functional diversity is measured using various indices that incorporate distinct community attributes. Community deconstruction is a way to disentangle species responses to ecological processes by grouping species with similar traits. We used these two approaches to determine whether they are improvements over traditional measures (e.g., species composition, abundance, biomass) for identification of the main processes driving dung beetle (Scarabaeinae) community structure in a fragmented mainland-island landscape in southern Brazilian Atlantic Forest. We sampled five sites in each of four large forest areas, two on the mainland and two on the island. Sampling was performed in 2012 and 2013. We collected abundance and biomass data from 100 sampling points distributed over 20 sampling sites. We studied environmental, spatial and temporal effects on dung beetle community across three spatial scales, i.e., between sites, between areas and mainland-island. The γ-diversity based on species abundance was mainly attributed to β-diversity as a consequence of the increase in mean α- and β-diversity between areas. Variation partitioning on abundance, biomass and functional diversity showed scale-dependence of processes structuring dung beetle metacommunities. We identified two major groups of responses among 17 functional groups. In general, environmental filters were important at both local and regional scales. Spatial factors were important at the intermediate scale. Our study supports the notion of scale-dependence of environmental, spatial and temporal processes in the distribution

The scale of supersymmetry breaking as a free parameter

International Nuclear Information System (INIS)

Polonsky, N.

2001-01-01

While supersymmetric extensions of the Standard Model can be fully described in terms of explicitly broken global supersymmetry, this description is only effective. Once related to spontaneous breaking in a more fundamental theory, the effective parameters translate to functions of two distinct scales, the scale of spontaneous supersymmetry breaking and the scale of its mediation to the standard-model fields. The scale dependence will be written explicitly and the full spectrum of supersymmetry breaking operators which emerges will be explored. It will be shown that, contrary to common lore, scale-dependent operators can play an important role in determining the phenomenology. For example, theories with low-energy supersymmetry breaking, such as gauge mediation, may correspond to a scalar potential which is quite different than in theories with high-energy supersymmetry breaking, such as gravity mediation. As a concrete example, the Higgs mass prediction will be discussed in some detail and its upper bound will be shown to be sensitive to the supersymmetry breaking scale

Zooming in and out: Scale dependence of extrinsic and intrinsic factors affecting salt marsh erosion

Science.gov (United States)

Wang, Heng; van der Wal, Daphne; Li, Xiangyu; van Belzen, Jim; Herman, Peter M. J.; Hu, Zhan; Ge, Zhenming; Zhang, Liquan; Bouma, Tjeerd J.

2017-07-01

Salt marshes are valuable ecosystems that provide important ecosystem services. Given the global scale of marsh loss due to climate change and coastal squeeze, there is a pressing need to identify the critical extrinsic (wind exposure and foreshore morphology) and intrinsic factors (soil and vegetation properties) affecting the erosion of salt marsh edges. In this study, we quantified rates of cliff lateral retreat (i.e., the eroding edge of a salt marsh plateau) using a time series of aerial photographs taken over four salt marsh sites in the Westerschelde estuary, the Netherlands. In addition, we experimentally quantified the erodibility of sediment cores collected from the marsh edge of these four marshes using wave tanks. Our results revealed the following: (i) at the large scale, wind exposure and the presence of pioneer vegetation in front of the cliff were the key factors governing cliff retreat rates; (ii) at the intermediate scale, foreshore morphology was partially related to cliff retreat; (iii) at the local scale, the erodibility of the sediment itself at the marsh edge played a large role in determining the cliff retreat rate; and (iv) at the mesocosm scale, cliff erodibility was determined by soil properties and belowground root biomass. Thus, both extrinsic and intrinsic factors determined the fate of the salt marsh but at different scales. Our study highlights the importance of understanding the scale dependence of the factors driving the evolution of salt marsh landscapes.

Scale-dependence of land use effects on water quality of streams in agricultural catchments

International Nuclear Information System (INIS)

Buck, Oliver; Niyogi, Dev K.; Townsend, Colin R.

2004-01-01

The influence of land use on water quality in streams is scale-dependent and varies in time and space. In this study, land cover patterns and stocking rates were used as measures of agricultural development in two pasture and one native grassland catchment in New Zealand and were related to water quality in streams of various orders. The amount of pasture per subcatchment correlated well to total nitrogen and nitrate in one catchment and turbidity and total phosphorous in the other catchment. Stocking rates were only correlated to total phosphorous in one pasture catchment but showed stronger correlations to ammonium, total phosphorous and total nitrogen in the other pasture catchment. Winter and spring floods were significant sources of nutrients and faecal coliforms from one of the pasture catchments into a wetland complex. Nutrient and faecal coliform concentrations were better predicted by pastural land cover in fourth-order than in second-order streams. This suggests that upstream land use is more influential in larger streams, while local land use and other factors may be more important in smaller streams. These temporal and spatial scale effects indicate that water-monitoring schemes need to be scale-sensitive. - Land use influences water quality of streams at various spatial scales

Scale-dependence of land use effects on water quality of streams in agricultural catchments

Energy Technology Data Exchange (ETDEWEB)

Buck, Oliver; Niyogi, Dev K.; Townsend, Colin R

2004-07-01

The influence of land use on water quality in streams is scale-dependent and varies in time and space. In this study, land cover patterns and stocking rates were used as measures of agricultural development in two pasture and one native grassland catchment in New Zealand and were related to water quality in streams of various orders. The amount of pasture per subcatchment correlated well to total nitrogen and nitrate in one catchment and turbidity and total phosphorous in the other catchment. Stocking rates were only correlated to total phosphorous in one pasture catchment but showed stronger correlations to ammonium, total phosphorous and total nitrogen in the other pasture catchment. Winter and spring floods were significant sources of nutrients and faecal coliforms from one of the pasture catchments into a wetland complex. Nutrient and faecal coliform concentrations were better predicted by pastural land cover in fourth-order than in second-order streams. This suggests that upstream land use is more influential in larger streams, while local land use and other factors may be more important in smaller streams. These temporal and spatial scale effects indicate that water-monitoring schemes need to be scale-sensitive. - Land use influences water quality of streams at various spatial scales.

Scale-dependent intrinsic entropies of complex time series.

Science.gov (United States)

Yeh, Jia-Rong; Peng, Chung-Kang; Huang, Norden E

2016-04-13

Multi-scale entropy (MSE) was developed as a measure of complexity for complex time series, and it has been applied widely in recent years. The MSE algorithm is based on the assumption that biological systems possess the ability to adapt and function in an ever-changing environment, and these systems need to operate across multiple temporal and spatial scales, such that their complexity is also multi-scale and hierarchical. Here, we present a systematic approach to apply the empirical mode decomposition algorithm, which can detrend time series on various time scales, prior to analysing a signal's complexity by measuring the irregularity of its dynamics on multiple time scales. Simulated time series of fractal Gaussian noise and human heartbeat time series were used to study the performance of this new approach. We show that our method can successfully quantify the fractal properties of the simulated time series and can accurately distinguish modulations in human heartbeat time series in health and disease. © 2016 The Author(s).

State and location dependence of action potential metabolic cost in cortical pyramidal neurons

NARCIS (Netherlands)

Hallermann, Stefan; de Kock, Christiaan P. J.; Stuart, Greg J.; Kole, Maarten H. P.

2012-01-01

Action potential generation and conduction requires large quantities of energy to restore Na+ and K+ ion gradients. We investigated the subcellular location and voltage dependence of this metabolic cost in rat neocortical pyramidal neurons. Using Na+/K+ charge overlap as a measure of action

State and location dependence of action potential metabolic cost in cortical pyramidal neurons

NARCIS (Netherlands)

Hallermann, S.; de Kock, C.P.J.; Stuart, G.J.; Kole, M.H.

2012-01-01

Action potential generation and conduction requires large quantities of energy to restore Na + and K + ion gradients. We investigated the subcellular location and voltage dependence of this metabolic cost in rat neocortical pyramidal neurons. Using Na +K + charge overlap as a measure of action

Scaling in the sine-Gordon theory

International Nuclear Information System (INIS)

Ben-Abraham, S.I.

1976-01-01

It is shown that both the classical and the quantum sine-Gordon theory depend on a single scaling parameter and therefore the coupling constant cannot be freely chosen. To introduce a meaningful coupling constant it is proposed to include higher Fourier terms in the sine-Gordon potential. The two term case is exactly solvable. (Auth.)

Geometry-Dependent Electrostatics near Contact Lines

International Nuclear Information System (INIS)

Chou, Tom

2001-01-01

Long-ranged electrostatic interactions in electrolytes modify contact angles on charged substrates in a scale and geometry-dependent manner. For angles measured at scales smaller than the typical Debye screening length, the wetting geometry near the contact line must be explicitly considered. Using variational and asymptotic methods, we derive new transcendental equations for the contact angle as functions of the electrostatic potential only at the three phase contact line. Analytic expressions are found in certain limits and compared with predictions for contact angles measured with lower resolution. An estimate for electrostatic contributions to line tension is also given

The predictive validity of the Drinking-Related Cognitions Scale in alcohol-dependent patients under abstinence-oriented treatment

Directory of Open Access Journals (Sweden)

Sawayama Toru

2012-05-01

Full Text Available Abstract Background Cognitive factors associated with drinking behavior such as positive alcohol expectancies, self-efficacy, perception of impaired control over drinking and perception of drinking problems are considered to have a significant influence on treatment effects and outcome in alcohol-dependent patients. However, the development of a rating scale on lack of perception or denial of drinking problems and impaired control over drinking has not been substantial, even though these are important factors in patients under abstinence-oriented treatment as well as participants in self-help groups such as Alcoholics Anonymous (AA. The Drinking-Related Cognitions Scale (DRCS is a new self-reported rating scale developed to briefly measure cognitive factors associated with drinking behavior in alcohol-dependent patients under abstinence-oriented treatment, including positive alcohol expectancies, abstinence self-efficacy, perception of impaired control over drinking, and perception of drinking problems. Here, we conducted a prospective cohort study to explore the predictive validity of DRCS. Methods Participants in this study were 175 middle-aged and elderly Japanese male patients who met the DSM-IV Diagnostic Criteria for Alcohol Dependence. DRCS scores were recorded before and after the inpatient abstinence-oriented treatment program, and treatment outcome was evaluated one year after discharge. Results Of the 175 participants, 30 were not available for follow-up; thus the number of subjects for analysis in this study was 145. When the total DRCS score and subscale scores were compared before and after inpatient treatment, a significant increase was seen for both scores. Both the total DRCS score and each subscale score were significantly related to total abstinence, percentage of abstinent days, and the first drinking occasion during the one-year post-treatment period. Therefore, good treatment outcome was significantly predicted by low

Incorporating Scale-Dependent Fracture Stiffness for Improved Reservoir Performance Prediction

Science.gov (United States)

Crawford, B. R.; Tsenn, M. C.; Homburg, J. M.; Stehle, R. C.; Freysteinson, J. A.; Reese, W. C.

2017-12-01

We present a novel technique for predicting dynamic fracture network response to production-driven changes in effective stress, with the potential for optimizing depletion planning and improving recovery prediction in stress-sensitive naturally fractured reservoirs. A key component of the method involves laboratory geomechanics testing of single fractures in order to develop a unique scaling relationship between fracture normal stiffness and initial mechanical aperture. Details of the workflow are as follows: tensile, opening mode fractures are created in a variety of low matrix permeability rocks with initial, unstressed apertures in the micrometer to millimeter range, as determined from image analyses of X-ray CT scans; subsequent hydrostatic compression of these fractured samples with synchronous radial strain and flow measurement indicates that both mechanical and hydraulic aperture reduction varies linearly with the natural logarithm of effective normal stress; these stress-sensitive single-fracture laboratory observations are then upscaled to networks with fracture populations displaying frequency-length and length-aperture scaling laws commonly exhibited by natural fracture arrays; functional relationships between reservoir pressure reduction and fracture network porosity, compressibility and directional permeabilities as generated by such discrete fracture network modeling are then exported to the reservoir simulator for improved naturally fractured reservoir performance prediction.

Scaling behaviour of Fisher and Shannon entropies for the exponential-cosine screened coulomb potential

Science.gov (United States)

Abdelmonem, M. S.; Abdel-Hady, Afaf; Nasser, I.

2017-07-01

The scaling laws are given for the entropies in the information theory, including the Shannon's entropy, its power, the Fisher's information and the Fisher-Shannon product, using the exponential-cosine screened Coulomb potential. The scaling laws are specified, in the r-space, as a function of |μ - μc, nℓ|, where μ is the screening parameter and μc, nℓ its critical value for the specific quantum numbers n and ℓ. Scaling laws for other physical quantities, such as energy eigenvalues, the moments, static polarisability, transition probabilities, etc. are also given. Some of these are reported for the first time. The outcome is compared with the available literatures' results.

Regulatory potential for increasing small scale grid connected photovoltaic (PV) deployment in Australia

International Nuclear Information System (INIS)

Sivaraman, Deepak; Horne, Ralph E.

2011-01-01

The last decade has seen significant innovation and change in regulatory incentives to support photovoltaic deployment globally. With high fossil fuel dependency and abundant solar resource availability in Australia, grid connected photovoltaics are a viable low carbon technology option in existing electricity grids. Drawing on international examples, the potential to increase grid PV deployment through government response and regulation is explored. For each renewable energy certificate (REC) earned by small scale photovoltaics until 2012, the market provides four additional certificates under the current banded renewable targets. Our analysis indicates that REC eligibility is not accurately estimated currently, and an energy model is developed to calculate the variance. The energy model estimates as much as 26% additional REC's to be obtained by a 3 kWp PV system, when compared to the currently used regulatory method. Moreover, the provision of REC's increases benefits to PV technologies, in the process distorting CO 2 abatement (0.21 tonne/REC) by 68%, when PV displaces peaking natural gas plants. Consideration of the secondary effects of a banded structure on emissions trading market is important in the context of designing a range of initiatives intended to support a transition to a low carbon electricity sector. - Research Highlights: →Grid connected photovoltaics hedge spikes in peak demand summer electricity prices. →Nationwide feed in tariff and new building regulations needed to increase PV deployment. →Australia has transitioned from a solar rebate to a banded solar credit structure. →The currently used regulatory deeming method underestimates REC eligibility by 27%. →The banded structure can potentially distort CO 2 abatement by as much as 68%.

Analysis of Medium-Scale Solar Thermal Systems and Their Potential in Lithuania

OpenAIRE

Valančius, Rokas; Jurelionis, Andrius; Jonynas, Rolandas; Katinas, Vladislovas; Perednis, Eugenijus

2015-01-01

Medium-scale solar hot water systems with a total solar panel area varying from 60 to 166 m 2 have been installed in Lithuania since 2002. However, the performance of these systems varies depending on the type of energy users, equipment and design of the systems, as well as their maintenance. The aim of this paper was to analyse operational SHW systems from the perspective of energy production and economic benefit as well as to outline the differences of their actual performance compared to t...

Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids

Science.gov (United States)

Covey, Dan P.; Bunner, Kendra D.; Schuweiler, Douglas R.; Cheer, Joseph F.; Garris, Paul A.

2018-01-01

The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement

Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids.

Science.gov (United States)

Covey, Dan P; Bunner, Kendra D; Schuweiler, Douglas R; Cheer, Joseph F; Garris, Paul A

2016-06-01

The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement

Temperature scaling method for Markov chains.

Science.gov (United States)

Crosby, Lonnie D; Windus, Theresa L

2009-01-22

The use of ab initio potentials in Monte Carlo simulations aimed at investigating the nucleation kinetics of water clusters is complicated by the computational expense of the potential energy determinations. Furthermore, the common desire to investigate the temperature dependence of kinetic properties leads to an urgent need to reduce the expense of performing simulations at many different temperatures. A method is detailed that allows a Markov chain (obtained via Monte Carlo) at one temperature to be scaled to other temperatures of interest without the need to perform additional large simulations. This Markov chain temperature-scaling (TeS) can be generally applied to simulations geared for numerous applications. This paper shows the quality of results which can be obtained by TeS and the possible quantities which may be extracted from scaled Markov chains. Results are obtained for a 1-D analytical potential for which the exact solutions are known. Also, this method is applied to water clusters consisting of between 2 and 5 monomers, using Dynamical Nucleation Theory to determine the evaporation rate constant for monomer loss. Although ab initio potentials are not utilized in this paper, the benefit of this method is made apparent by using the Dang-Chang polarizable classical potential for water to obtain statistical properties at various temperatures.

Sequential dependencies in magnitude scaling of loudness

DEFF Research Database (Denmark)

Joshi, Suyash Narendra; Jesteadt, Walt

2013-01-01

Ten normally hearing listeners used a programmable sone-potentiometer knob to adjust the level of a 1000-Hz sinusoid to match the loudness of numbers presented to them in a magnitude production task. Three different power-law exponents (0.15, 0.30, and 0.60) and a log-law with equal steps in d......B were used to program the sone-potentiometer. The knob settings systematically influenced the form of the loudness function. Time series analysis was used to assess the sequential dependencies in the data, which increased with increasing exponent and were greatest for the log-law. It would be possible......, therefore, to choose knob properties that minimized these dependencies. When the sequential dependencies were removed from the data, the slope of the loudness functions did not change, but the variability decreased. Sequential dependencies were only present when the level of the tone on the previous trial...

Disrupted coupling of large-scale networks is associated with relapse behaviour in heroin-dependent men

Science.gov (United States)

Li, Qiang; Liu, Jierong; Wang, Wei; Wang, Yarong; Li, Wei; Chen, Jiajie; Zhu, Jia; Yan, Xuejiao; Li, Yongbin; Li, Zhe; Ye, Jianjun; Wang, Wei

2018-01-01

Background It is unknown whether impaired coupling among 3 core large-scale brain networks (salience [SN], default mode [DMN] and executive control networks [ECN]) is associated with relapse behaviour in treated heroin-dependent patients. Methods We conducted a prospective resting-state functional MRI study comparing the functional connectivity strength among healthy controls and heroin-dependent men who had either relapsed or were in early remission. Men were considered to be either relapsed or in early remission based on urine drug screens during a 3-month follow-up period. We also examined how the coupling of large-scale networks correlated with relapse behaviour among heroin-dependent men. Results We included 20 controls and 50 heroin-dependent men (26 relapsed and 24 early remission) in our analyses. The relapsed men showed greater connectivity than the early remission and control groups between the dorsal anterior cingulate cortex (key node of the SN) and the dorsomedial prefrontal cortex (included in the DMN). The relapsed men and controls showed lower connectivity than the early remission group between the left dorsolateral prefrontal cortex (key node of the left ECN) and the dorsomedial prefrontal cortex. The percentage of positive urine drug screens positively correlated with the coupling between the dorsal anterior cingulate cortex and dorsomedial prefrontal cortex, but negatively correlated with the coupling between the left dorsolateral prefrontal cortex and dorsomedial prefrontal cortex. Limitations We examined deficits in only 3 core networks leading to relapse behaviour. Other networks may also contribute to relapse. Conclusion Greater coupling between the SN and DMN and lower coupling between the left ECN and DMN is associated with relapse behaviour. These findings may shed light on the development of new treatments for heroin addiction. PMID:29252165

Generation dependent cancer targeting potential of poly(propyleneimine) dendrimer.

Science.gov (United States)

Kesharwani, Prashant; Tekade, Rakesh K; Jain, Narendra K

2014-07-01

Dendrimer-mediated delivery of bioactive is a successful and widely explored concept. This paper desribes comparative data pertaining to generation dependent cancer targeting propensity of Poly(propyleneimine) (PPI) dendrimers. This debut report reportsthe drug targeting and antciancer potential of different dendrimer generations. PPI dendrimers of different generations (3.0G, 4.0G and 5.0G) were synthesized and loaded with Melphalan. Results from loading, hemolysis, hematologic, cytotoxicty and flow cytometry assay depicted that as the generation of dendrimer increased from fourth to fifth, the only parameter i.e. toxicty is increased exponentionally. However, others parameters, i.e. loading, sustained release behavior, and targeting efficacy increased negligibly. Kaplan-Meier survival curves clearly depicted comparable therapeutic potential of PPI4M with PPI5M. In vivo investigations in Balb/c mice again favored 4.0G PPI dendrimer to be preferable nanocarrier for anticancer drug delivery owing to analogous anticancer potential. The outcomes of the investigation evidently projects 4.0G PPI dendrimer over 3.0G and 5.0G dendrimer in respect of its drug delivery benefit as well as superior biocompatibility. Thus, much against the common belief, 4.0G PPI dendrimers may be considered to be optimum in respect of drug delivery precluding the use of much more toxic 5.0G PPI dendrimer, which offers no benefit over 4.0G. Copyright © 2014 Elsevier Ltd. All rights reserved.

Energy-Dependent microscopic optical potential for p+{sup 9}Be elastic scattering

Energy Technology Data Exchange (ETDEWEB)

Maridi, H. M., E-mail: h.maridi@gmail.com [Physics Department, Faculty of Science, Cairo University, Giza 12613 (Egypt); Physics Department, Faculty of Applied Science, Taiz University, Taiz (Yemen); Farag, M. Y. H., E-mail: yehiafarag@cu.edu.eg; Esmael, E. H. [Physics Department, Faculty of Applied Science, Taiz University, Taiz (Yemen)

2016-06-10

The p+{sup 9}Be elastic scattering at an energy range up to 200 MeV/nucleon is analyzed using the single-folding model. The density- and isospin-dependent M3Y-Paris nucleon-nucleon (NN) interaction is used for the real part and the NN-scattering amplitude of the high-energy approximation for the imaginary one. The analysis reveals that the cross-section data are reproduced well at energies up to 100 MeV/nucleon by use of the partial-wave expansion. For higher energies, the eikonal approximation give results better than the partial-wave expansion calculations. The volume integrals of the optical-potential parts have systematic energy dependencies, and they are parameterized in empirical formulas.

Local and non-local potentials for deuteron elastic scattering

International Nuclear Information System (INIS)

Ramirez, J.A.

1976-01-01

The nucleon--nucleus local potential (central and spin--orbit) and the deuteron--nucleus nonlocal potential (central, spin--orbit, spin--radial tensor) are calculated by the folding-model (FM). Simple analytic expressions are obtained for the nucleon--nucleus potential by the use of Gaussians to represent the nucleon--nucleus potential and the charge and mass densities of the target. The analytic expressions give qualitative descriptions of phenomenological nucleon--nucleus interactions. A systematic target--mass dependence of realistic local FM deueron potentials is also included. Local-equivalent, energy-dependent, deuteron potentials are obtained from the nonlocal FM deuteron potentials and the energy dependence of the local potential parameters are presented. The local FM deuteron potential is tested for 60 Ni(d,d) 60 Ni at E/sub α/ = 15 MeV by comparing the predictions of the FM potentials with data in which all five polarization moments were measured. A qualitative fit to the data is obtained, but it overestimates the volume integral of the central potential by 7%. Energy-dependence effects are estimated by evaluating the local-equivalent potentials at E/sub α/ = 30 MeV and comparing the predictions to the E/sub α/ = 15 MeV potentials. The energy dependence of the central potential dominates the angular dependence of all five observables while the energy dependence of the spin--orbit and tensor potentials produces only scale changes (approx. 3%) in the vector and tensor analyzing powers. The scattering formalism for a spin-1 on a spin-0 target nucleus, and a description of the coupled--channels computer code DDUNC1 which treats the spin--radial tensor potential exactly, are included

Temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with a soft on-site potential.

Science.gov (United States)

Yang, Linlin; Li, Nianbei; Li, Baowen

2014-12-01

The temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with soft on-site potential (soft-KG) are investigated systematically. Similarly to the previously studied hard-KG lattices, the existence of renormalized phonons is also confirmed in soft-KG lattices. In particular, the temperature dependence of the renormalized phonon frequency predicted by a classical field theory is verified by detailed numerical simulations. However, the thermal conductivities of soft-KG lattices exhibit the opposite trend in temperature dependence in comparison with those of hard-KG lattices. The interesting thing is that the temperature-dependent thermal conductivities of both soft- and hard-KG lattices can be interpreted in the same framework of effective phonon theory. According to the effective phonon theory, the exponents of the power-law dependence of the thermal conductivities as a function of temperature are only determined by the exponents of the soft or hard on-site potentials. These theoretical predictions are consistently verified very well by extensive numerical simulations.

Temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with a soft on-site potential

Science.gov (United States)

Yang, Linlin; Li, Nianbei; Li, Baowen

2014-12-01

The temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with soft on-site potential (soft-KG) are investigated systematically. Similarly to the previously studied hard-KG lattices, the existence of renormalized phonons is also confirmed in soft-KG lattices. In particular, the temperature dependence of the renormalized phonon frequency predicted by a classical field theory is verified by detailed numerical simulations. However, the thermal conductivities of soft-KG lattices exhibit the opposite trend in temperature dependence in comparison with those of hard-KG lattices. The interesting thing is that the temperature-dependent thermal conductivities of both soft- and hard-KG lattices can be interpreted in the same framework of effective phonon theory. According to the effective phonon theory, the exponents of the power-law dependence of the thermal conductivities as a function of temperature are only determined by the exponents of the soft or hard on-site potentials. These theoretical predictions are consistently verified very well by extensive numerical simulations.

Potential dependent adhesion forces on bare and underpotential deposition modified electrode surfaces

Energy Technology Data Exchange (ETDEWEB)

Serafin, J.M.; Hsieh, S.J.; Monahan, J.; Gewirth, A.A. [Univ. of Illinois, Urbana, IL (United States)

1998-12-03

Adhesion force measurements are used to determine the potential dependence of the force of adhesion between a Si{sub 3}N{sub 4} cantilever and a Au(111) surface modified by the underpotential deposition (upd) of Bi or Cu in acid solution or by oxide formation. The measured work of adhesion is near zero for most of the potential region examined in Bi upd but rises after the formation of a full Bi monolayer. The work of adhesion is high at positive potentials for Cu upd but then decreases as the Cu partial and full monolayers are formed. The work of adhesion is low in the oxide region on Au(111) but rises following the sulfate disordering transition at 1.1 V vs NHE. These results are interpreted in terms of the degree of solvent order on the electrode surface.

Relevant energy scale of color confinement from lattice QCD

International Nuclear Information System (INIS)

Yamamoto, Arata; Suganuma, Hideo

2009-01-01

We propose a new lattice framework to extract the relevant gluonic energy scale of QCD phenomena which is based on a 'cut' on link variables in momentum space. This framework is expected to be broadly applicable to all lattice QCD calculations. Using this framework, we quantitatively determine the relevant energy scale of color confinement, through the analyses of the quark-antiquark potential and meson masses. The relevant energy scale of color confinement is found to be below 1.5 GeV in the Landau gauge. In fact, the string tension is almost unchanged even after cutting off the high-momentum gluon component above 1.5 GeV. When the relevant low-energy region is cut, the quark-antiquark potential is approximately reduced to a Coulomb-like potential, and each meson becomes a quasifree quark pair. As an analytical model calculation, we also investigate the dependence of the Richardson potential on the cut, and find the consistent behavior with the lattice result.

Spin-dependent exciton-exciton interaction potential in two- and three-dimensional structure semiconductors under excitation

International Nuclear Information System (INIS)

Nguyen Ba An; Hoang Ngoc Cam; Nguyen Trung Dan

1990-08-01

Analytical expressions of the exciton-exciton interaction potentials have been approximately derived in both 2D and 3D structure materials exhibiting explicit dependences on exciton momentum difference, momentum transfer, electron-hole effective mass ratio and two-exciton state spin symmetry. Numerical calculations show that the character of the exciton-exciton interaction is determined by all of the above-mentioned dependences. (author). 32 refs, 7 figs

A Realization of a Quasi-Random Walk for Atoms in Time-Dependent Optical Potentials

Directory of Open Access Journals (Sweden)

Torsten Hinkel

2015-09-01

Full Text Available We consider the time dependent dynamics of an atom in a two-color pumped cavity, longitudinally through a side mirror and transversally via direct driving of the atomic dipole. The beating of the two driving frequencies leads to a time dependent effective optical potential that forces the atom into a non-trivial motion, strongly resembling a discrete random walk behavior between lattice sites. We provide both numerical and analytical analysis of such a quasi-random walk behavior.

Exact solutions of the Schrodinger equation with the position-dependent mass for a hard-core potential

International Nuclear Information System (INIS)

Dong Shihai; Lozada-Cassou, M.

2005-01-01

The exact solutions of two-dimensional Schrodinger equation with the position-dependent mass for a hard-core potential are obtained. The eigenvalues related to the position-dependent masses μ 1 and μ 2 , the potential well depth V 0 and the effective range r 0 can be calculated by the boundary condition. We generalize this quantum system to three-dimensional case. The special cases for l=0,1 are studied in detail. For l=0 and c=0, we find that the energy levels will increase with the parameters μ 2 , V 0 and r 0 if μ 1 >μ 2

Time-scale and extent at which large-scale circulation modes determine the wind and solar potential in the Iberian Peninsula

International Nuclear Information System (INIS)

Jerez, Sonia; Trigo, Ricardo M

2013-01-01

The North Atlantic Oscillation (NAO), the East Atlantic (EA) and the Scandinavian (SCAND) modes are the three main large-scale circulation patterns driving the climate variability of the Iberian Peninsula. This study assesses their influence in terms of solar (photovoltaic) and wind power generation potential (SP and WP) and evaluates their skill as predictors. For that we use a hindcast regional climate simulation to retrieve the primary meteorological variables involved, surface solar radiation and wind speed. First we identify that the maximum influence of the various modes occurs on the interannual variations of the monthly mean SP and WP series, being generally more relevant in winter. Second we find that in this time-scale and season, SP (WP) varies up to 30% (40%) with respect to the mean climatology between years with opposite phases of the modes, although the strength and the spatial distribution of the signals differ from one month to another. Last, the skill of a multi-linear regression model (MLRM), built using the NAO, EA and SCAND indices, to reconstruct the original wintertime monthly series of SP and WP was investigated. The reconstructed series (when the MLRM is calibrated for each month individually) correlate with the original ones up to 0.8 at the interannual time-scale. Besides, when the modeled series for each individual month are merged to construct an October-to-March monthly series, and after removing the annual cycle in order to account for monthly anomalies, these correlate 0.65 (0.55) with the original SP (WP) series in average. These values remain fairly stable when the calibration and reconstruction periods differ, thus supporting up to a point the predictive potential of the method at the time-scale assessed here. (letter)

Exact Time-Dependent Exchange-Correlation Potential in Electron Scattering Processes

Science.gov (United States)

Suzuki, Yasumitsu; Lacombe, Lionel; Watanabe, Kazuyuki; Maitra, Neepa T.

2017-12-01

We identify peak and valley structures in the exact exchange-correlation potential of time-dependent density functional theory that are crucial for time-resolved electron scattering in a model one-dimensional system. These structures are completely missed by adiabatic approximations that, consequently, significantly underestimate the scattering probability. A recently proposed nonadiabatic approximation is shown to correctly capture the approach of the electron to the target when the initial Kohn-Sham state is chosen judiciously, and it is more accurate than standard adiabatic functionals but ultimately fails to accurately capture reflection. These results may explain the underestimation of scattering probabilities in some recent studies on molecules and surfaces.

Trait-specific dependence in romantic relationships.

Science.gov (United States)

Ellis, Bruce J; Simpson, Jeffry A; Campbell, Lorne

2002-10-01

Informed by three theoretical frameworks--trait psychology, evolutionary psychology, and interdependence theory--we report four investigations designed to develop and test the reliability and validity of a new construct and accompanying multiscale inventory, the Trait-Specific Dependence Inventory (TSDI). The TSDI assesses comparisons between present and alternative romantic partners on major dimensions of mate value. In Study 1, principal components analyses revealed that the provisional pool of theory-generated TSDI items were represented by six factors: Agreeable/Committed, Resource Accruing Potential, Physical Prowess, Emotional Stability, Surgency, and Physical Attractiveness. In Study 2, confirmatory factor analysis replicated these results on a different sample and tested how well different structural models fit the data. Study 3 provided evidence for the convergent and discriminant validity of the six TSDI scales by correlating each one with a matched personality trait scale that did not explicitly incorporate comparisons between partners. Study 4 provided further validation evidence, revealing that the six TSDI scales successfully predicted three relationship outcome measures--love, time investment, and anger/upset--above and beyond matched sets of traditional personality trait measures. These results suggest that the TSDI is a reliable, valid, and unique construct that represents a new trait-specific method of assessing dependence in romantic relationships. The construct of trait-specific dependence is introduced and linked with other theories of mate value.

Time-variable gravity potential components for optical clock comparisons and the definition of international time scales

International Nuclear Information System (INIS)

Voigt, C.; Denker, H.; Timmen, L.

2016-01-01

The latest generation of optical atomic clocks is approaching the level of one part in 10 18 in terms of frequency stability and uncertainty. For clock comparisons and the definition of international time scales, a relativistic redshift effect of the clock frequencies has to be taken into account at a corresponding uncertainty level of about 0.1 m 2 s -2 and 0.01 m in terms of gravity potential and height, respectively. Besides the predominant static part of the gravity potential, temporal variations must be considered in order to avoid systematic frequency shifts. Time-variable gravity potential components induced by tides and non-tidal mass redistributions are investigated with regard to the level of one part in 10 18 . The magnitudes and dominant time periods of the individual gravity potential contributions are investigated globally and for specific laboratory sites together with the related uncertainty estimates. The basics of the computation methods are presented along with the applied models, data sets and software. Solid Earth tides contribute by far the most dominant signal with a global maximum amplitude of 4.2 m 2 s -2 for the potential and a range (maximum-to-minimum) of up to 1.3 and 10.0 m 2 s -2 in terms of potential differences between specific laboratories over continental and intercontinental scales, respectively. Amplitudes of the ocean tidal loading potential can amount up to 1.25 m 2 s -2 , while the range of the potential between specific laboratories is 0.3 and 1.1 m 2 s -2 over continental and intercontinental scales, respectively. These are the only two contributors being relevant at a 10 -17 level. However, several other time-variable potential effects can particularly affect clock comparisons at the 10 -18 level. Besides solid Earth pole tides, these are non-tidal mass redistributions in the atmosphere, the oceans and the continental water storage. (authors)

Molecular wave function and effective adiabatic potentials calculated by extended multi-configuration time-dependent Hartree-Fock method

Energy Technology Data Exchange (ETDEWEB)

Kato, Tsuyoshi; Ide, Yoshihiro; Yamanouchi, Kaoru [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1, Hongo Bunkyo-ku, Tokyo, 113-0033 (Japan)

2015-12-31

We first calculate the ground-state molecular wave function of 1D model H{sub 2} molecule by solving the coupled equations of motion formulated in the extended multi-configuration time-dependent Hartree-Fock (MCTDHF) method by the imaginary time propagation. From the comparisons with the results obtained by the Born-Huang (BH) expansion method as well as with the exact wave function, we observe that the memory size required in the extended MCTDHF method is about two orders of magnitude smaller than in the BH expansion method to achieve the same accuracy for the total energy. Second, in order to provide a theoretical means to understand dynamical behavior of the wave function, we propose to define effective adiabatic potential functions and compare them with the conventional adiabatic electronic potentials, although the notion of the adiabatic potentials is not used in the extended MCTDHF approach. From the comparison, we conclude that by calculating the effective potentials we may be able to predict the energy differences among electronic states even for a time-dependent system, e.g., time-dependent excitation energies, which would be difficult to be estimated within the BH expansion approach.

Modified Fourth-Order Kinetic Energy Gradient Expansion with Hartree Potential-Dependent Coefficients.

Science.gov (United States)

Constantin, Lucian A; Fabiano, Eduardo; Della Sala, Fabio

2017-09-12

Using the semiclassical neutral atom theory, we developed a modified fourth-order kinetic energy (KE) gradient expansion (GE4m) that keeps unchanged all the linear-response terms of the uniform electron gas and gives a significant improvement with respect to the known semilocal functionals for both large atoms and jellium surfaces. On the other hand, GE4m is not accurate for light atoms; thus, we modified the GE4m coefficients making them dependent on a novel ingredient, the reduced Hartree potential, recently introduced in the Journal of Chemical Physics 2016, 145, 084110, in the context of exchange functionals. The resulting KE gradient expansion functional, named uGE4m, belongs to the novel class of u-meta-generalized-gradient-approximations (uMGGA) whose members depend on the conventional ingredients (i.e., the reduced gradient and Laplacian of the density) as well as on the reduced Hartree potential. To test uGE4m, we defined an appropriate benchmark (including total KE and KE differences for atoms, molecules and jellium clusters) for gradient expansion functionals, that is, including only those systems which are mainly described by a slowly varying density regime. While most of the GGA and meta-GGA KE functionals (we tested 18 of them) are accurate for some properties and inaccurate for others, uGE4m shows a consistently good performance for all the properties considered. This represents a qualitative boost in the KE functional development and highlights the importance of the reduced Hartree potential for the construction of next-generation KE functionals.

A manganese-hydrogen battery with potential for grid-scale energy storage

Science.gov (United States)

Chen, Wei; Li, Guodong; Pei, Allen; Li, Yuzhang; Liao, Lei; Wang, Hongxia; Wan, Jiayu; Liang, Zheng; Chen, Guangxu; Zhang, Hao; Wang, Jiangyan; Cui, Yi

2018-05-01

Batteries including lithium-ion, lead-acid, redox-flow and liquid-metal batteries show promise for grid-scale storage, but they are still far from meeting the grid's storage needs such as low cost, long cycle life, reliable safety and reasonable energy density for cost and footprint reduction. Here, we report a rechargeable manganese-hydrogen battery, where the cathode is cycled between soluble Mn2+ and solid MnO2 with a two-electron reaction, and the anode is cycled between H2 gas and H2O through well-known catalytic reactions of hydrogen evolution and oxidation. This battery chemistry exhibits a discharge voltage of 1.3 V, a rate capability of 100 mA cm-2 (36 s of discharge) and a lifetime of more than 10,000 cycles without decay. We achieve a gravimetric energy density of 139 Wh kg-1 (volumetric energy density of 210 Wh l-1), with the theoretical gravimetric energy density of 174 Wh kg-1 (volumetric energy density of 263 Wh l-1) in a 4 M MnSO4 electrolyte. The manganese-hydrogen battery involves low-cost abundant materials and has the potential to be scaled up for large-scale energy storage.

Using fine-scale fuel measurements to assess wildland fuels, potential fire behavior and hazard mitigation treatments in the southeastern USA

International Nuclear Information System (INIS)

Ottmar, Roger D.; Blake, John I.; Crolly, William T.

2012-01-01

The inherent spatial and temporal heterogeneity of fuelbeds in forests of the southeastern United States may require fine scale fuel measurements for providing reliable fire hazard and fuel treatment effectiveness estimates. In a series of five papers, an intensive, fine scale fuel inventory from the Savanna River Site in the southeastern United States is used for building fuelbeds and mapping fire behavior potential, evaluating fuel treatment options for effectiveness, and providing a comparative analysis of landscape modeled fire behavior using three different data sources including the Fuel Characteristic Classification System, LANDFIRE, and the Southern Wildfire Risk Assessment. The research demonstrates that fine scale fuel measurements associated with fuel inventories repeated over time can be used to assess broad scale wildland fire potential and hazard mitigation treatment effectiveness in the southeastern USA and similar fire prone regions. Additional investigations will be needed to modify and improve these processes and capture the true potential of these fine scale data sets for fire and fuel management planning.

Phosphorus Import Dependency and Recycling Potential in the Global Phosphorus Mosaic

Science.gov (United States)

Powers, S. M.

2017-12-01

Nations differ widely in terms of recent P consumption trends and fertilizer trade dependencies, reflecting dynamic and globally uneven P fertilizer production, consumption, export, and import. Recovered P from urban and agricultural wastes can provide renewable sources that supplant the need to import P fertilizer, but to date, research on P recycling potential has been highly spatially segregated. Understanding of the global distribution of P recycling potential and options, and how these intersect with P import dependencies, could be used to guide long-term, spatially-prioritized planning for P, food, and water security. We integrated recent data on national P fertilizer flows, subnational P use, and landscape features within a global grid to understand how these constraints on future options for P use are distributed worldwide. This analysis illustrates several regions where combinations of high population density, cropland extent, and manure P production provide islands of opportunity for P recycling in mixed crop-livestock and populous agricultural areas. At the same time, nations with lower import ratios (net P import:consumption) contained a disproportionately large share of manure-rich croplands and populous croplands. As a further demonstration of the kinds of integrated comparisons that are possible using global land use data sets in combination with P, worldwide similarities and distinctions for P emerged from a cluster analysis. These kinds of socioeconomic-geographic patterns may foretell distinct P futures as societies address spatially uneven options for P, food, and water security.

Diverse effects of distance cutoff and residue interval on the performance of distance-dependent atom-pair potential in protein structure prediction.

Science.gov (United States)

Yao, Yuangen; Gui, Rong; Liu, Quan; Yi, Ming; Deng, Haiyou

2017-12-08

As one of the most successful knowledge-based energy functions, the distance-dependent atom-pair potential is widely used in all aspects of protein structure prediction, including conformational search, model refinement, and model assessment. During the last two decades, great efforts have been made to improve the reference state of the potential, while other factors that also strongly affect the performance of the potential have been relatively less investigated. Based on different distance cutoffs (from 5 to 22 Å) and residue intervals (from 0 to 15) as well as six different reference states, we constructed a series of distance-dependent atom-pair potentials and tested them on several groups of structural decoy sets collected from diverse sources. A comprehensive investigation has been performed to clarify the effects of distance cutoff and residue interval on the potential's performance. Our results provide a new perspective as well as a practical guidance for optimizing distance-dependent statistical potentials. The optimal distance cutoff and residue interval are highly related with the reference state that the potential is based on, the measurements of the potential's performance, and the decoy sets that the potential is applied to. The performance of distance-dependent statistical potential can be significantly improved when the best statistical parameters for the specific application environment are adopted.

A rate-dependent multi-scale crack model for concrete

NARCIS (Netherlands)

Karamnejad, A.; Nguyen, V.P.; Sluys, L.J.

2013-01-01

A multi-scale numerical approach for modeling cracking in heterogeneous quasi-brittle materials under dynamic loading is presented. In the model, a discontinuous crack model is used at macro-scale to simulate fracture and a gradient-enhanced damage model has been used at meso-scale to simulate

On the universality of MOG weak field approximation at galaxy cluster scale

Directory of Open Access Journals (Sweden)

Ivan De Martino

2017-07-01

Full Text Available In its weak field limit, Scalar-tensor-vector gravity theory introduces a Yukawa-correction to the gravitational potential. Such a correction depends on the two parameters, α which accounts for the modification of the gravitational constant, and μ⁎−1 which represents the scale length on which the scalar field propagates. These parameters were found to be universal when the modified gravitational potential was used to fit the galaxy rotation curves and the mass profiles of galaxy clusters, both without Dark Matter. We test the universality of these parameters using the temperature anisotropies due to the thermal Sunyaev–Zeldovich effect. In our model the intra-cluster gas is in hydrostatic equilibrium within the modified gravitational potential well and it is described by a polytropic equation of state. We predict the thermal Sunyaev–Zeldovich temperature anisotropies produced by Coma cluster, and we compare them with those obtained using the Planck 2013 Nominal maps. In our analysis, we find α and the scale length, respectively, to be consistent and to depart from their universal values. Our analysis points out that the assumption of the universality of the Yukawa-correction to the gravitational potential is ruled out at more than 3.5σ at galaxy clusters scale, while demonstrating that such a theory of gravity is capable to fit the cluster profile if the scale dependence of the gravitational potential is restored.

The effect of urban growth on landscape-scale restoration for a fire-dependent songbird.

Science.gov (United States)

Pickens, Bradley A; Marcus, Jeffrey F; Carpenter, John P; Anderson, Scott; Taillie, Paul J; Collazo, Jaime A

2017-04-15

A landscape-scale perspective on restoration ecology has been advocated, but few studies have informed restoration with landscape metrics or addressed broad-scale threats. Threats such as urban growth may affect restoration effectiveness in a landscape context. Here, we studied longleaf pine savanna in the rapidly urbanizing southeastern United States where a habitat-specialist bird, Bachman's sparrow (Peucaea aestivalis), is closely associated with savanna vegetation structure and frequent fire. Our objectives were to construct a species distribution model for Bachman's sparrow, determine the relationship between fire and urbanization, quantify the urban growth effect (2010-2090), identify potential restoration areas, and determine the interaction between restoration potential and urban growth by 2050. Number of patches, patch size, and isolation metrics were used to evaluate scenarios. The species distribution model was 88% accurate and emphasized multiscale canopy cover characteristics, fire, and percent habitat. Fires were less common urban areas, and this fire suppression effect exacerbated urban growth effects. For restoration scenarios, canopy cover reduction by 30% resulted in nearly double the amount of habitat compared to the prescribed fire scenario; canopy cover reduction resulted in larger patch sizes and less patch isolation compared to current conditions. The effect of urban growth on restoration scenarios was unequal. Seventy-four percent of restoration areas from the prescribed fire scenario overlapped with projected urban growth, whereas the canopy cover reduction scenario only overlapped by 9%. We emphasize the benefits of simultaneously considering the effects of urban growth and landscape-scale restoration potential to promote a landscape with greater patch sizes and less isolation. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Cortical Double-Opponent Cells in Color Perception: Perceptual Scaling and Chromatic Visual Evoked Potentials.

Science.gov (United States)

Nunez, Valerie; Shapley, Robert M; Gordon, James

2018-01-01

In the early visual cortex V1, there are currently only two known neural substrates for color perception: single-opponent and double-opponent cells. Our aim was to explore the relative contributions of these neurons to color perception. We measured the perceptual scaling of color saturation for equiluminant color checkerboard patterns (designed to stimulate double-opponent neurons preferentially) and uniformly colored squares (designed to stimulate only single-opponent neurons) at several cone contrasts. The spatially integrative responses of single-opponent neurons would produce the same response magnitude for checkerboards as for uniform squares of the same space-averaged cone contrast. However, perceived saturation of color checkerboards was higher than for the corresponding squares. The perceptual results therefore imply that double-opponent cells are involved in color perception of patterns. We also measured the chromatic visual evoked potential (cVEP) produced by the same stimuli; checkerboard cVEPs were much larger than those for corresponding squares, implying that double-opponent cells also contribute to the cVEP response. The total Fourier power of the cVEP grew sublinearly with cone contrast. However, the 6-Hz Fourier component's power grew linearly with contrast-like saturation perception. This may also indicate that cortical coding of color depends on response dynamics.

Surface and zeta-potentials of silver halide single crystals: pH-dependence in comparison to particle systems

International Nuclear Information System (INIS)

Selmani, Atiða; Kallay, Nikola; Preočanin, Tajana; Lützenkirchen, Johannes

2014-01-01

We have carried out surface and zeta-potential measurements on AgCl and AgBr single crystals. As for particle systems we find that, surprisingly and previously unnoted, the zeta-potential exhibits pH-dependence, while the surface potential does not. A possible interpretation of these observations is the involvement of water ions in the interfacial equilibria and in particular, stronger affinity of the hydroxide ion compared to the proton. The pH-dependence of the zeta-potential can be suppressed at sufficiently high silver concentrations, which agrees with previous measurements in particle systems where no pH-dependence was found at high halide ion concentrations. The results suggest a subtle interplay between the surface potential determining the halide and silver ion concentrations, and the water ions. Whenever the charge due to the halide and silver ions is sufficiently high, the influence of the proton/hydroxide ion on the zeta-potential vanishes. This might be related to the water structuring at the relevant interfaces which should be strongly affected by the surface potential. Another interesting observation is accentuation of the assumed water ion effect on the zeta-potential at the flat single crystal surfaces compared to the corresponding silver halide colloids. Previous generic MD simulations have indeed predicted that hydroxide ion adsorption is accentuated on flat/rigid surfaces. A thermodynamic model for AgI single crystals was developed to describe the combined effects of iodide, silver and water ions, based on two independently previously published models for AgI (that only consider constituent and background electrolyte ions) and inert surfaces (that only consider water and background electrolyte ions). The combined model correctly predicts all the experimentally observed trends. (paper)

Menthol's potential effects on nicotine dependence: a tobacco industry perspective.

Science.gov (United States)

Yerger, Valerie B

2011-05-01

To examine what the tobacco industry knows about the potential effects menthol may have on nicotine dependence. A snowball strategy was used to systematically search the Legacy Tobacco Documents Library (http://legacy.library.ucsf.edu/) between 22 February and 29 April, 2010. Of the approximately 11 million documents available in the Legacy Tobacco Documents Library, the iterative searches returned tens of thousands of results. We qualitatively analysed a final collection of 309 documents relevant the effects of menthol on nicotine dependence. The tobacco industry knows that menthol overrides the harsh taste of tobacco and alleviates nicotine's irritating effects, synergistically interacts with nicotine, stimulates the trigeminal nerve to elicit a 'liking' response for a tobacco product, and makes low tar, low nicotine tobacco products more acceptable to smokers than non-mentholated low delivery products. Menthol is not only used in cigarettes as a flavour additive; tobacco companies know that menthol also has sensory effects and interacts with nicotine to produce tobacco products that are easier to smoke, thereby making it easier to expose smokers, especially those who are new and uninitiated, to the addictive power of nicotine.

Scale-dependence of transverse momentum correlations in Pb - Au collisions at 158A GeV/c

CERN Document Server

Adamová, D; Antonczyk, D; Appelshäuser, H; Belaga, V; Bielcikova, S; Braun-Munzinger, P; Busch, O; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Dubitzky, W; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Zeev; Garabatos, C; Glässel, P; Holeczek, J; Kushpil, V; Maas, A; Marín, A; Milosevic, J; Milov, A; Miskowiec, D; Panebratsev, Yu A; Petchenova, O; Petracek, V; Pfeiffer, A; Ploskon, M; Radomski, S; Rak, acn J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Sedykh, S; Shimansky, S; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, Itzhak; Tsiledakis, G; Wessels, J P; Wienold, T; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V

2008-01-01

We present results on transverse momentum correlations of charged particle pairs produced in Pb-Au collisions at 158$A$ GeV/$c$ at the Super Proton Synchrotron. The transverse momentum correlations have been studied as a function of collision centrality, angular separation of the particle pairs, transverse momentum and charge sign. We demonstrate that the results are in agreement with previous findings in scale-independent analyses at the same beam energy. Employing the two-particle momentum correlator $$ and the cumulative $p_t$ variable $x(p_t)$, we identify, using the scale-dependent approach presented in this paper, different sources contributing to the measured correlations, such as quantum and Coulomb correlations, elliptic flow and mini-jet fragmentation.

Scale-dependence of transverse momentum correlations in PbAu collisions at 158A GeV/c

Science.gov (United States)

Ceres Collaboration; Adamová, D.; Agakichiev, G.; Antończyk, D.; Appelshäuser, H.; Belaga, V.; Bielcikova, S.; Braun-Munzinger, P.; Busch, O.; Cherlin, A.; Damjanović, S.; Dietel, T.; Dietrich, L.; Drees, A.; Dubitzky, W.; Esumi, S. I.; Filimonov, K.; Fomenko, K.; Fraenkel, Z.; Garabatos, C.; Glässel, P.; Holeczek, J.; Kushpil, V.; Maas, A.; Marín, A.; Milošević, J.; Milov, A.; Miśkowiec, D.; Panebrattsev, Yu.; Petchenova, O.; Petráček, V.; Pfeiffer, A.; Płoskoń, M.; Radomski, S.; Rak, J.; Ravinovich, I.; Rehak, P.; Sako, H.; Schmitz, W.; Sedykh, S.; Shimansky, S.; Stachel, J.; Šumbera, M.; Tilsner, H.; Tserruya, I.; Tsiledakis, G.; Wessels, J. P.; Wienold, T.; Wurm, J. P.; Xie, W.; Yurevich, S.; Yurevich, V.

2008-10-01

We present results on transverse momentum correlations of charged particle pairs produced in PbAu collisions at 158A GeV/c at the Super Proton Synchrotron. The transverse momentum correlations have been studied as a function of collision centrality, angular separation of the particle pairs, transverse momentum and charge sign. We demonstrate that the results are in agreement with previous findings in scale-independent analyses at the same beam energy. Employing the two-particle momentum correlator and the cumulative p variable x(p), we identify, using the scale-dependent approach presented in this paper, different sources contributing to the measured correlations, such as quantum and Coulomb correlations, elliptic flow and mini-jet fragmentation.

On scale dependence of hardness

International Nuclear Information System (INIS)

Shorshorov, M.Kh.; Alekhin, V.P.; Bulychev, S.I.

1977-01-01

The concept of hardness as a structure-sensitive characteristic of a material is considered. It is shown that in conditions of a decreasing stress field under the inventor the hardness function is determined by the average distance, Lsub(a), between the stops (fixed and sessile dislocations, segregation particles, etc.). In the general case, Lsub(a) depends on the size of the impression and explains the great diversity of hardness functions. The concept of average true deformation rate on depression is introduced

Scale dependence of rock friction at high work rate.

Science.gov (United States)

Yamashita, Futoshi; Fukuyama, Eiichi; Mizoguchi, Kazuo; Takizawa, Shigeru; Xu, Shiqing; Kawakata, Hironori

2015-12-10

Determination of the frictional properties of rocks is crucial for an understanding of earthquake mechanics, because most earthquakes are caused by frictional sliding along faults. Prior studies using rotary shear apparatus revealed a marked decrease in frictional strength, which can cause a large stress drop and strong shaking, with increasing slip rate and increasing work rate. (The mechanical work rate per unit area equals the product of the shear stress and the slip rate.) However, those important findings were obtained in experiments using rock specimens with dimensions of only several centimetres, which are much smaller than the dimensions of a natural fault (of the order of 1,000 metres). Here we use a large-scale biaxial friction apparatus with metre-sized rock specimens to investigate scale-dependent rock friction. The experiments show that rock friction in metre-sized rock specimens starts to decrease at a work rate that is one order of magnitude smaller than that in centimetre-sized rock specimens. Mechanical, visual and material observations suggest that slip-evolved stress heterogeneity on the fault accounts for the difference. On the basis of these observations, we propose that stress-concentrated areas exist in which frictional slip produces more wear materials (gouge) than in areas outside, resulting in further stress concentrations at these areas. Shear stress on the fault is primarily sustained by stress-concentrated areas that undergo a high work rate, so those areas should weaken rapidly and cause the macroscopic frictional strength to decrease abruptly. To verify this idea, we conducted numerical simulations assuming that local friction follows the frictional properties observed on centimetre-sized rock specimens. The simulations reproduced the macroscopic frictional properties observed on the metre-sized rock specimens. Given that localized stress concentrations commonly occur naturally, our results suggest that a natural fault may lose its

Construction of high-dimensional neural network potentials using environment-dependent atom pairs.

Science.gov (United States)

Jose, K V Jovan; Artrith, Nongnuch; Behler, Jörg

2012-05-21

An accurate determination of the potential energy is the crucial step in computer simulations of chemical processes, but using electronic structure methods on-the-fly in molecular dynamics (MD) is computationally too demanding for many systems. Constructing more efficient interatomic potentials becomes intricate with increasing dimensionality of the potential-energy surface (PES), and for numerous systems the accuracy that can be achieved is still not satisfying and far from the reliability of first-principles calculations. Feed-forward neural networks (NNs) have a very flexible functional form, and in recent years they have been shown to be an accurate tool to construct efficient PESs. High-dimensional NN potentials based on environment-dependent atomic energy contributions have been presented for a number of materials. Still, these potentials may be improved by a more detailed structural description, e.g., in form of atom pairs, which directly reflect the atomic interactions and take the chemical environment into account. We present an implementation of an NN method based on atom pairs, and its accuracy and performance are compared to the atom-based NN approach using two very different systems, the methanol molecule and metallic copper. We find that both types of NN potentials provide an excellent description of both PESs, with the pair-based method yielding a slightly higher accuracy making it a competitive alternative for addressing complex systems in MD simulations.

Exponential dependence of potential barrier height on biased voltages of inorganic/organic static induction transistor

International Nuclear Information System (INIS)

Zhang Yong; Yang Jianhong; Cai Xueyuan; Wang Zaixing

2010-01-01

The exponential dependence of the potential barrier height φ c on the biased voltages of the inorganic/organic static induction transistor (SIT/OSIT) through a normalized approach in the low-current regime is presented. It shows a more accurate description than the linear expression of the potential barrier height. Through the verification of the numerical calculated and experimental results, the exponential dependence of φ c on the applied biases can be used to derive the I-V characteristics. For both SIT and OSIT, the calculated results, using the presented relationship, are agreeable with the experimental results. Compared to the previous linear relationship, the exponential description of φ c can contribute effectively to reduce the error between the theoretical and experimental results of the I-V characteristics. (semiconductor devices)

Double Dissociation of Spike Timing-Dependent Potentiation and Depression by Subunit-Preferring NMDA Receptor Antagonists in Mouse Barrel Cortex

NARCIS (Netherlands)

Banerjee, A.; Meredith, R.M.; Rodriguez-Moreno, A.; Mierau, S.B.; Auberson, Y.P.; Paulsen, O.

2009-01-01

Spike timing-dependent plasticity (STDP) is a strong candidate for an N-methyl-D-aspartate (NMDA) receptor-dependent form of synaptic plasticity that could underlie the development of receptive field properties in sensory neocortices. Whilst induction of timing-dependent long-term potentiation

Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells.

Science.gov (United States)

Johnson, Stuart L; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M; Roberts, Terri P; Masetto, Sergio; Knipper, Marlies; Kros, Corné J; Marcotti, Walter

2011-06-01

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials were intrinsically generated by immature IHCs of altricial rodents and that apical IHCs showed bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter acetylcholine fine-tunes the IHC's resting membrane potential (V(m)), and as such is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the V(m) of apical and basal IHCs by triggering small-conductance Ca(2+)-activated K(+) (SK2) channels. We propose that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway.

Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells

Science.gov (United States)

Johnson, Stuart L.; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M.; Roberts, Terri P.; Masetto, Sergio; Knipper, Marlies; Kros, Corné J.; Marcotti, Walter

2011-01-01

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion cells and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials are intrinsically generated by immature IHCs of altricial rodents and that apical IHCs exhibit bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter ACh, by fine-tuning the IHC’s resting membrane potential (Vm), is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the Vm of apical and basal IHCs by activating SK2 channels. We hypothesize that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway. PMID:21572434

Age-dependent leaf physiology and consequences for crown-scale carbon uptake during the dry season in an Amazon evergreen forest.

Science.gov (United States)

Albert, Loren P; Wu, Jin; Prohaska, Neill; de Camargo, Plinio Barbosa; Huxman, Travis E; Tribuzy, Edgard S; Ivanov, Valeriy Y; Oliveira, Rafael S; Garcia, Sabrina; Smith, Marielle N; Oliveira Junior, Raimundo Cosme; Restrepo-Coupe, Natalia; da Silva, Rodrigo; Stark, Scott C; Martins, Giordane A; Penha, Deliane V; Saleska, Scott R

2018-03-04

Satellite and tower-based metrics of forest-scale photosynthesis generally increase with dry season progression across central Amazônia, but the underlying mechanisms lack consensus. We conducted demographic surveys of leaf age composition, and measured the age dependence of leaf physiology in broadleaf canopy trees of abundant species at a central eastern Amazon site. Using a novel leaf-to-branch scaling approach, we used these data to independently test the much-debated hypothesis - arising from satellite and tower-based observations - that leaf phenology could explain the forest-scale pattern of dry season photosynthesis. Stomatal conductance and biochemical parameters of photosynthesis were higher for recently mature leaves than for old leaves. Most branches had multiple leaf age categories simultaneously present, and the number of recently mature leaves increased as the dry season progressed because old leaves were exchanged for new leaves. These findings provide the first direct field evidence that branch-scale photosynthetic capacity increases during the dry season, with a magnitude consistent with increases in ecosystem-scale photosynthetic capacity derived from flux towers. Interactions between leaf age-dependent physiology and shifting leaf age-demographic composition are sufficient to explain the dry season photosynthetic capacity pattern at this site, and should be considered in vegetation models of tropical evergreen forests. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Plane-dependent ML scatter scaling: 3D extension of the 2D simulated single scatter (SSS) estimate

Science.gov (United States)

Rezaei, Ahmadreza; Salvo, Koen; Vahle, Thomas; Panin, Vladimir; Casey, Michael; Boada, Fernando; Defrise, Michel; Nuyts, Johan

2017-08-01

Scatter correction is typically done using a simulation of the single scatter, which is then scaled to account for multiple scatters and other possible model mismatches. This scaling factor is determined by fitting the simulated scatter sinogram to the measured sinogram, using only counts measured along LORs that do not intersect the patient body, i.e. ‘scatter-tails’. Extending previous work, we propose to scale the scatter with a plane dependent factor, which is determined as an additional unknown in the maximum likelihood (ML) reconstructions, using counts in the entire sinogram rather than only the ‘scatter-tails’. The ML-scaled scatter estimates are validated using a Monte-Carlo simulation of a NEMA-like phantom, a phantom scan with typical contrast ratios of a 68Ga-PSMA scan, and 23 whole-body 18F-FDG patient scans. On average, we observe a 12.2% change in the total amount of tracer activity of the MLEM reconstructions of our whole-body patient database when the proposed ML scatter scales are used. Furthermore, reconstructions using the ML-scaled scatter estimates are found to eliminate the typical ‘halo’ artifacts that are often observed in the vicinity of high focal uptake regions.

Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism

Science.gov (United States)

Price, Alex; Pearson, Victoria K.; Schwenzer, Susanne P.; Miot, Jennyfer; Olsson-Francis, Karen

2018-01-01

This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1–3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate

Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism

Directory of Open Access Journals (Sweden)

Alex Price

2018-03-01

Full Text Available This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1–3.7 Ga match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with

Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism.

Science.gov (United States)

Price, Alex; Pearson, Victoria K; Schwenzer, Susanne P; Miot, Jennyfer; Olsson-Francis, Karen

2018-01-01

This work considers the hypothetical viability of microbial nitrate-dependent Fe 2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe 2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe 2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1-3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe 2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate

New phenomena in the standard no-scale supergravity model

CERN Document Server

Kelley, S; Nanopoulos, Dimitri V; Zichichi, Antonino; Kelley, S; Lopez, J L; Nanopoulos, D V; Zichichi, A

1994-01-01

We revisit the no-scale mechanism in the context of the simplest no-scale supergravity extension of the Standard Model. This model has the usual five-dimensional parameter space plus an additional parameter \\xi_{3/2}\\equiv m_{3/2}/m_{1/2}. We show how predictions of the model may be extracted over the whole parameter space. A necessary condition for the potential to be stable is {\\rm Str}{\\cal M}^4>0, which is satisfied if \\bf m_{3/2}\\lsim2 m_{\\tilde q}. Order of magnitude calculations reveal a no-lose theorem guaranteeing interesting and potentially observable new phenomena in the neutral scalar sector of the theory which would constitute a ``smoking gun'' of the no-scale mechanism. This new phenomenology is model-independent and divides into three scenarios, depending on the ratio of the weak scale to the vev at the minimum of the no-scale direction. We also calculate the residual vacuum energy at the unification scale (C_0\\, m^4_{3/2}), and find that in typical models one must require C_0>10. Such constrai...

Opioid dependence and substitution therapy: thymoquinone as potential novel supplement therapy for better outcome for methadone maintenance therapy substitution therapy

Science.gov (United States)

Adnan, Liyana Hazwani Mohd; Bakar, Nor Hidayah Abu; Mohamad, Nasir

2014-01-01

Methadone is widely being used for opioid substitution therapy. However, the administration of methadone to opioid dependent individual is frequently accompanied by withdrawal syndrome and chemical dependency develops. Other than that, it is also difficult to retain patients in the treatment programme making their retention rates are decreasing over time. This article is written to higlights the potential use of prophetic medicines, Nigella sativa, as a supplement for opioid dependent receiving methadone. It focuses on the potential role of N. sativa and its major active compound, Thymoquinone (TQ) as a calcium channel blocking agent to reduce withdrawal syndrome and opioid dependency. PMID:25859295

Measurements of the large-scale direct-current Earth potential and possible implications for the geomagnetic dynamo.

Science.gov (United States)

1985-07-05

The magnitude of the large-scale direct-current earth potential was measured on a section of a recently laid transatlantic telecommunications cable. Analysis of the data acquired on the 4476-kilometer cable yielded a mean direct-current potential drop of less than about 0.072 +/- 0.050 millivolts per kilometer. Interpreted in terms of a generation of the potential by the earth's geodynamo, such a small value of the mean potential implies that the toroidal and poloidal magnetic fields of the dynamo are approximately equal at the core-mantle boundary.

Scale-dependency of macroinvertebrate communities: responses to contaminated sediments within run-of-river dams.

Science.gov (United States)

Colas, Fanny; Archaimbault, Virginie; Devin, Simon

2011-03-01

Due to their nutrient recycling function and their importance in food-webs, macroinvertebrates are essential for the functioning of aquatic ecosystems. These organisms also constitute an important component of biodiversity. Sediment evaluation and monitoring is an essential aspect of ecosystem monitoring since sediments represent an important component of aquatic habitats and are also a potential source of contamination. In this study, we focused on macroinvertebrate communities within run-of-river dams, that are prime areas for sediment and pollutant accumulation. Little is known about littoral macroinvertebrate communities within run-of-river dam or their response to sediment levels and pollution. We therefore aimed to evaluate the following aspects: the functional and structural composition of macroinvertebrate communities in run-of-river dams; the impact of pollutant accumulation on such communities, and the most efficient scales and tools needed for the biomonitoring of contaminated sediments in such environments. Two run-of-river dams located in the French alpine area were selected and three spatial scales were examined: transversal (banks and channel), transversal x longitudinal (banks/channel x tail/middle/dam) and patch scale (erosion, sedimentation and vegetation habitats). At the patch scale, we noted that the heterogeneity of littoral habitats provided many available niches that allow for the development of diversified macroinvertebrate communities. This implies highly variable responses to contamination. Once combined on a global 'banks' spatial scale, littoral habitats can highlight the effects of toxic disturbances. Copyright © 2011 Elsevier B.V. All rights reserved.

A study of the angular momentum dependence of the phase shift for finite range and Coulomb potentials

International Nuclear Information System (INIS)

Valluri, S.R.; Romo, W.J.

1989-01-01

The dependence of the phase shift δ l (k) on the angular momentum l is investigated. An analytic expression for the derivative of the phase shift with respect to angular momentum is derived for a class of potentials that includes complex and real potentials. The potentials behave like the finite range potential for small r and like a Coulomb potential for large r. Specific examples like the square well, the pure point charge Coulomb and a combination of a square well and the Coulomb potential are analytically treated. Possible applications are briefly indicated. (orig.)

A multi scale model for small scale plasticity

International Nuclear Information System (INIS)

Zbib, Hussein M.

2002-01-01

Full text.A framework for investigating size-dependent small-scale plasticity phenomena and related material instabilities at various length scales ranging from the nano-microscale to the mesoscale is presented. The model is based on fundamental physical laws that govern dislocation motion and their interaction with various defects and interfaces. Particularly, a multi-scale model is developed merging two scales, the nano-microscale where plasticity is determined by explicit three-dimensional dislocation dynamics analysis providing the material length-scale, and the continuum scale where energy transport is based on basic continuum mechanics laws. The result is a hybrid simulation model coupling discrete dislocation dynamics with finite element analyses. With this hybrid approach, one can address complex size-dependent problems, including dislocation boundaries, dislocations in heterogeneous structures, dislocation interaction with interfaces and associated shape changes and lattice rotations, as well as deformation in nano-structured materials, localized deformation and shear band

Non-linear corrections to the cosmological matter power spectrum and scale-dependent galaxy bias: implications for parameter estimation

International Nuclear Information System (INIS)

Hamann, Jan; Hannestad, Steen; Melchiorri, Alessandro; Wong, Yvonne Y Y

2008-01-01

We explore and compare the performances of two non-linear correction and scale-dependent biasing models for the extraction of cosmological information from galaxy power spectrum data, especially in the context of beyond-ΛCDM (CDM: cold dark matter) cosmologies. The first model is the well known Q model, first applied in the analysis of Two-degree Field Galaxy Redshift Survey data. The second, the P model, is inspired by the halo model, in which non-linear evolution and scale-dependent biasing are encapsulated in a single non-Poisson shot noise term. We find that while the two models perform equally well in providing adequate correction for a range of galaxy clustering data in standard ΛCDM cosmology and in extensions with massive neutrinos, the Q model can give unphysical results in cosmologies containing a subdominant free-streaming dark matter whose temperature depends on the particle mass, e.g., relic thermal axions, unless a suitable prior is imposed on the correction parameter. This last case also exposes the danger of analytic marginalization, a technique sometimes used in the marginalization of nuisance parameters. In contrast, the P model suffers no undesirable effects, and is the recommended non-linear correction model also because of its physical transparency

Non-linear corrections to the cosmological matter power spectrum and scale-dependent galaxy bias: implications for parameter estimation

Science.gov (United States)

Hamann, Jan; Hannestad, Steen; Melchiorri, Alessandro; Wong, Yvonne Y. Y.

2008-07-01

We explore and compare the performances of two non-linear correction and scale-dependent biasing models for the extraction of cosmological information from galaxy power spectrum data, especially in the context of beyond-ΛCDM (CDM: cold dark matter) cosmologies. The first model is the well known Q model, first applied in the analysis of Two-degree Field Galaxy Redshift Survey data. The second, the P model, is inspired by the halo model, in which non-linear evolution and scale-dependent biasing are encapsulated in a single non-Poisson shot noise term. We find that while the two models perform equally well in providing adequate correction for a range of galaxy clustering data in standard ΛCDM cosmology and in extensions with massive neutrinos, the Q model can give unphysical results in cosmologies containing a subdominant free-streaming dark matter whose temperature depends on the particle mass, e.g., relic thermal axions, unless a suitable prior is imposed on the correction parameter. This last case also exposes the danger of analytic marginalization, a technique sometimes used in the marginalization of nuisance parameters. In contrast, the P model suffers no undesirable effects, and is the recommended non-linear correction model also because of its physical transparency.

Approach to equilibrium of diffusion in a logarithmic potential.

Science.gov (United States)

Hirschberg, Ori; Mukamel, David; Schütz, Gunter M

2011-10-01

The late-time distribution function P(x,t) of a particle diffusing in a one-dimensional logarithmic potential is calculated for arbitrary initial conditions. We find a scaling solution with three surprising features: (i) the solution is given by two distinct scaling forms, corresponding to a diffusive (x∼t(1/2)) and a subdiffusive (x∼t(γ) with a given γfunction is selected by the initial condition, and (iii) depending on the tail of the initial condition, the scaling exponent that characterizes the scaling function is found to exhibit a transition from a continuously varying to a fixed value.

Evaluation of the small-scale hydro-energetic potential in micro-basins in Colombia

International Nuclear Information System (INIS)

Torres Q, E.; Castillo C, J.J.

1995-01-01

A definition of the small-scale hydroelectric power plants (PCHs, abbreviations in Spanish), its classification according to potency and fall and its classification as utilization form is present. The general parameters to PCHs design in aspects as topography studies, geology and geotechnical studies and hydrologic studies are described. The primary elements of a PCH, as dam (little dam), conduction, tank of charge, sand trap (water re claimer), floodgate, grating (network), pressure's pipe, fall, principal valve and turbine are shown. In the study of potential of micro-basins, general points as topography, draining, population, supply and demand of electric energy, morphology, hydrology, geology and hydraulic potential are consider

A study of the bound states for square potential wells with position-dependent mass

International Nuclear Information System (INIS)

Ganguly, A.; Kuru, S.; Negro, J.; Nieto, L.M.

2006-01-01

A potential well with position-dependent mass is studied for bound states. Applying appropriate matching conditions, a transcendental equation is derived for the energy eigenvalues. Numerical results are presented graphically and the variation of the energy of the bound states are calculated as a function of the well-width and mass

D-Dimensional Dirac Equation for Energy-Dependent Pseudoharmonic and Mie-type Potentials via SUSYQM

International Nuclear Information System (INIS)

Ikot, A.N.; Hassanabadi, H.; Maghsoodi, E.; Zarrinkamar, S.

2014-01-01

We investigate the approximate solution of the Dirac equation for energy-dependent pseudoharmonic and Mie-type potentials under the pseudospin and spin symmetries using the supersymmetry quantum mechanics. We obtain the bound-state energy equation in an analytical manner and comment on the system behavior via various figures and tables

Atomic-Scale Simulation of Electrochemical Processes at Electrode/Water Interfaces under Referenced Bias Potential.

Science.gov (United States)

Bouzid, Assil; Pasquarello, Alfredo

2018-04-19

Based on constant Fermi-level molecular dynamics and a proper alignment scheme, we perform simulations of the Pt(111)/water interface under variable bias potential referenced to the standard hydrogen electrode (SHE). Our scheme yields a potential of zero charge μ pzc of ∼0.22 eV relative to the SHE and a double layer capacitance C dl of ≃19 μF cm -2 , in excellent agreement with experimental measurements. In addition, we study the structural reorganization of the electrical double layer for bias potentials ranging from -0.92 eV to +0.44 eV and find that O down configurations, which are dominant at potentials above the pzc, reorient to favor H down configurations as the measured potential becomes negative. Our modeling scheme allows one to not only access atomic-scale processes at metal/water interfaces, but also to quantitatively estimate macroscopic electrochemical quantities.

Direction of information flow in large-scale resting-state networks is frequency-dependent.

Science.gov (United States)

Hillebrand, Arjan; Tewarie, Prejaas; van Dellen, Edwin; Yu, Meichen; Carbo, Ellen W S; Douw, Linda; Gouw, Alida A; van Straaten, Elisabeth C W; Stam, Cornelis J

2016-04-05

Normal brain function requires interactions between spatially separated, and functionally specialized, macroscopic regions, yet the directionality of these interactions in large-scale functional networks is unknown. Magnetoencephalography was used to determine the directionality of these interactions, where directionality was inferred from time series of beamformer-reconstructed estimates of neuronal activation, using a recently proposed measure of phase transfer entropy. We observed well-organized posterior-to-anterior patterns of information flow in the higher-frequency bands (alpha1, alpha2, and beta band), dominated by regions in the visual cortex and posterior default mode network. Opposite patterns of anterior-to-posterior flow were found in the theta band, involving mainly regions in the frontal lobe that were sending information to a more distributed network. Many strong information senders in the theta band were also frequent receivers in the alpha2 band, and vice versa. Our results provide evidence that large-scale resting-state patterns of information flow in the human brain form frequency-dependent reentry loops that are dominated by flow from parieto-occipital cortex to integrative frontal areas in the higher-frequency bands, which is mirrored by a theta band anterior-to-posterior flow.

Small-scale spatial variability of phenoxy acid mineralization potentials in transition zones with a multidisciplinary approach

DEFF Research Database (Denmark)

Pazarbasi, Meric Batioglu

The phenoxy acid group of herbicides is widely used to control broadleaf weeds, and it contaminates groundwater and surface water by leaching from agricultural soil or landfills. Due to the distinct vertical and horizontal gradients in nutrients and hydrologic exchange in transition zones...... in two transition zones, (1) the interfaces of unsaturated and saturated zones and (2) groundwater and surface water. Small-scale spatial variability of phenoxy acids was previously shown in topsoil; however, such small-scale studies are scarce in subsurface environments. We therefore studied the factors...... classes in the different mineralization potentials of discharge zones. Understanding of the natural attenuation potential of groundwater-surface water transition zones is important for stream water protection. In landfill-impacted groundwater-surface water interface, we further analyzed bacterial...

Dependency of global primary bioenergy crop potentials in 2050 on food systems, yields, biodiversity conservation and political stability

International Nuclear Information System (INIS)

Erb, Karl-Heinz; Haberl, Helmut; Plutzar, Christoph

2012-01-01

The future bioenergy crop potential depends on (1) changes in the food system (food demand, agricultural technology), (2) political stability and investment security, (3) biodiversity conservation, (4) avoidance of long carbon payback times from deforestation, and (5) energy crop yields. Using a biophysical biomass-balance model, we analyze how these factors affect global primary bioenergy potentials in 2050. The model calculates biomass supply and demand balances for eleven world regions, eleven food categories, seven food crop types and two livestock categories, integrating agricultural forecasts and scenarios with a consistent global land use and NPP database. The TREND scenario results in a global primary bioenergy potential of 77 EJ/yr, alternative assumptions on food-system changes result in a range of 26–141 EJ/yr. Exclusion of areas for biodiversity conservation and inaccessible land in failed states reduces the bioenergy potential by up to 45%. Optimistic assumptions on future energy crop yields increase the potential by up to 48%, while pessimistic assumptions lower the potential by 26%. We conclude that the design of sustainable bioenergy crop production policies needs to resolve difficult trade-offs such as food vs. energy supply, renewable energy vs. biodiversity conservation or yield growth vs. reduction of environmental problems of intensive agriculture. - Highlights: ► Global energy crop potentials in 2050 are calculated with a biophysical biomass-balance model. ► The study is focused on dedicated energy crops, forestry and residues are excluded. ► Depending on food-system change, global energy crop potentials range from 26–141 EJ/yr. ► Exclusion of protected areas and failed states may reduce the potential up to 45%. ► The bioenergy potential may be 26% lower or 45% higher, depending on energy crop yields.

The fermionic projector in a time-dependent external potential: Mass oscillation property and Hadamard states

Science.gov (United States)

Finster, Felix; Murro, Simone; Röken, Christian

2016-07-01

We give a non-perturbative construction of the fermionic projector in Minkowski space coupled to a time-dependent external potential which is smooth and decays faster than quadratically for large times. The weak and strong mass oscillation properties are proven. We show that the integral kernel of the fermionic projector is of the Hadamard form, provided that the time integral of the spatial sup-norm of the potential satisfies a suitable bound. This gives rise to an algebraic quantum field theory of Dirac fields in an external potential with a distinguished pure quasi-free Hadamard state.

The fermionic projector in a time-dependent external potential: Mass oscillation property and Hadamard states

International Nuclear Information System (INIS)

Finster, Felix; Murro, Simone; Röken, Christian

2016-01-01

We give a non-perturbative construction of the fermionic projector in Minkowski space coupled to a time-dependent external potential which is smooth and decays faster than quadratically for large times. The weak and strong mass oscillation properties are proven. We show that the integral kernel of the fermionic projector is of the Hadamard form, provided that the time integral of the spatial sup-norm of the potential satisfies a suitable bound. This gives rise to an algebraic quantum field theory of Dirac fields in an external potential with a distinguished pure quasi-free Hadamard state.

The fermionic projector in a time-dependent external potential: Mass oscillation property and Hadamard states

Energy Technology Data Exchange (ETDEWEB)

Finster, Felix, E-mail: finster@ur.de, E-mail: simone.murro@ur.de, E-mail: Christian.Roeken@mathematik.ur.de; Murro, Simone, E-mail: finster@ur.de, E-mail: simone.murro@ur.de, E-mail: Christian.Roeken@mathematik.ur.de; Röken, Christian, E-mail: finster@ur.de, E-mail: simone.murro@ur.de, E-mail: Christian.Roeken@mathematik.ur.de [Fakultät für Mathematik, Universität Regensburg, D-93040 Regensburg (Germany)

2016-07-15

We give a non-perturbative construction of the fermionic projector in Minkowski space coupled to a time-dependent external potential which is smooth and decays faster than quadratically for large times. The weak and strong mass oscillation properties are proven. We show that the integral kernel of the fermionic projector is of the Hadamard form, provided that the time integral of the spatial sup-norm of the potential satisfies a suitable bound. This gives rise to an algebraic quantum field theory of Dirac fields in an external potential with a distinguished pure quasi-free Hadamard state.

Scaling of saturation amplitudes in baroclinic instability

International Nuclear Information System (INIS)

Shepherd, T.G.

1994-01-01

By using finite-amplitude conservation laws for pseudomomentum and pseudoenergy, rigorous upper bounds have been derived on the saturation amplitudes in baroclinic instability for layered and continuously-stratified quasi-geostrophic models. Bounds have been obtained for both the eddy energy and the eddy potential enstrophy. The bounds apply to conservative (inviscid, unforced) flow, as well as to forced-dissipative flow when the dissipation is proportional to the potential vorticity. This approach provides an efficient way of extracting an analytical estimate of the dynamical scalings of the saturation amplitudes in terms of crucial non-dimensional parameters. A possible use is in constructing eddy parameterization schemes for zonally-averaged climate models. The scaling dependences are summarized, and compared with those derived from weakly-nonlinear theory and from baroclinic-adjustment estimates

Comparison of the effect of soft-core potentials and Coulombic potentials on bremsstrahlung during laser matter interaction

Science.gov (United States)

Pandit, Rishi R.; Becker, Valerie R.; Barrington, Kasey; Thurston, Jeremy; Ramunno, Lora; Ackad, Edward

2018-04-01

An intense, short laser pulse incident on rare-gas clusters can produce nano-plasmas containing energetic electrons. As these electrons undergo scattering, from both phonons and ions, they emit bremsstrahlung radiation. Here, we compare a theory of bremsstrahlung emission appropriate for the interaction of intense lasers with matter using soft-core potentials and Coulombic potentials. A new scaling for the radiation cross-section and the radiated power via bremsstrahlung is derived for a soft-core potential (which depends on the potential depth) and compared with the Coulomb potential. Calculations using the new scaling are performed for electrons in vacuum ultraviolet, infrared and mid-infrared laser pulses. The radiation cross-section and the radiation power via bremsstrahlung are found to increase rapidly with increases in the potential depth of up to around 200 eV and then become mostly saturated for larger depths while remaining constant for the Coulomb potential. In both cases, the radiation cross-section and the radiation power of bremsstrahlung decrease with increases in the laser wavelength. The ratio of the scattering amplitude for the soft-core potential and that for the Coulombic potential decreases exponentially with an increase in momentum transfer. The bremsstrahlung emission by electrons in plasmas may provide a broadband light source for diagnostics.

Dirac Particle for the Position Dependent Mass in the Generalized Asymmetric Woods-Saxon Potential

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Soner Alpdoğan

2014-01-01

Full Text Available The one-dimensional Dirac equation with position dependent mass in the generalized asymmetric Woods-Saxon potential is solved in terms of the hypergeometric functions. The transmission and reflection coefficients are obtained by considering the one-dimensional electric current density for the Dirac particle and the equation describing the bound states is found by utilizing the continuity conditions of the obtained wave function. Also, by using the generalized asymmetric Woods-Saxon potential solutions, the scattering states are found out without making calculation for the Woods-Saxon, Hulthen, cusp potentials, and so forth, which are derived from the generalized asymmetric Woods-Saxon potential and the conditions describing transmission resonances and supercriticality are achieved. At the same time, the data obtained in this work are compared with the results achieved in earlier studies and are observed to be consistent.

Opioid dependence and substitution therapy: thymoquinone as potential novel supplement therapy for better outcome for methadone maintenance therapy substitution therapy

Directory of Open Access Journals (Sweden)

Liyana Hazwani Mohd Adnan

2015-12-01

Full Text Available Methadone is widely being used for opioid substitution therapy. However, the administration of methadone to opioid dependent individual is frequently accompanied by withdrawal syndrome and chemical dependency develops. Other than that, it is also difficult to retain patients in the treatment programme making their retention rates are decreasing over time. This article is written to higlights the potential use of prophetic medicines, Nigella sativa, as a supplement for opioid dependent receiving methadone. It focuses on the potential role of N. sativa and its major active compound, Thymoquinone (TQ as a calcium channel blocking agent to reduce withdrawal syndrome and opioid dependency.

Exploring the correlation between annual precipitation and potential evaporation

Science.gov (United States)

Chen, X.; Buchberger, S. G.

2017-12-01

The interdependence between precipitation and potential evaporation is closely related to the classic Budyko framework. In this study, a systematic investigation of the correlation between precipitation and potential evaporation at the annual time step is conducted at both point scale and watershed scale. The point scale precipitation and potential evaporation data over the period of 1984-2015 are collected from 259 weather stations across the United States. The watershed scale precipitation data of 203 watersheds across the United States are obtained from the Model Parameter Estimation Experiment (MOPEX) dataset from 1983 to 2002; and potential evaporation data of these 203 watersheds in the same period are obtained from a remote-sensing algorithm. The results show that majority of the weather stations (77%) and watersheds (79%) exhibit a statistically significant negative correlation between annual precipitation and annual potential evaporation. The aggregated data cloud of precipitation versus potential evaporation follows a curve based on the combination of the Budyko-type equation and Bouchet's complementary relationship. Our result suggests that annual precipitation and potential evaporation are not independent when both Budyko's hypothesis and Bouchet's hypothesis are valid. Furthermore, we find that the wet surface evaporation, which is controlled primarily by short wave radiation as defined in Bouchet's hypothesis, exhibits less dependence on precipitation than the potential evaporation. As a result, we suggest that wet surface evaporation is a better representation of energy supply than potential evaporation in the Budyko framework.

GIS-based approach for potential analysis of solar PV generation at the regional scale: A case study of Fujian Province

International Nuclear Information System (INIS)

Sun, Yan-wei; Hof, Angela; Wang, Run; Liu, Jian; Lin, Yan-jie; Yang, De-wei

2013-01-01

Spatial variation of solar energy is crucial for the estimation of the regional potential and selection of construction location. This paper presents a case study of using high resolution grid map of solar radiation combined with the other restriction factors to evaluate the comprehensive potential analysis of solar PV generation at the regional scale, in order to present a framework of decision support tool for solar energy management in a regional area. The cost of PV generation is calculated based on the geographical distribution of technical potential. Moreover, geospatial supply curve (GSC) is employed to portray the evolution of available potential of photovoltaics (PV) generation with the increase of the generation cost. By integrating the economic evaluation variables of net present value and simple payback period, grid-based economic feasibility of PV generation project is then carried out under two feed-in-tariff scenarios. Finally, total CO 2 reduction potential and its spatial distribution in the study area are calculated. The results confirm that PV technology provides high potential for roof-top application and large-scale PV stations. Additionally, determining a reasonable feed-in tariff is essential for expanding the application of solar PV energy. The findings improve understanding of regional renewable energy strategies and the supply/demand assessment. - Highlights: • We developed a grid-based comprehensive potential analysis framework of solar energy at the regional scale. • We evaluated the technical potential of solar PV generation. • We calculated the cost of PV generation and got the geospatial supply curve (GSC) of Fujian Province. • PV technology provides high potential for roof-top application and large-scale PV stations. • Determining a reasonable feed-in tariff is essential for expanding the application of solar PV energy

Temperature and baryon-chemical-potential-dependent bag pressure for a deconfining phase transition

International Nuclear Information System (INIS)

Patra, B.K.; Singh, C.P.

1996-01-01

We explore the consequences of a bag model developed by Leonidov et al. for the deconfining phase transition in which the bag pressure is made to depend on the temperature and baryon chemical potential in order to ensure the entropy and baryon number conservation at the phase boundary together with the Gibbs construction for an equilibrium phase transition. We show that the bag pressure thus obtained yields an anomalous increasing behavior with the increasing baryon chemical potential at a fixed temperature which defies a physical interpretation. We demonstrate that the inclusion of the perturbative interactions in the QGP phase removes this difficulty. Further consequences of the modified bag pressure are discussed. copyright 1996 The American Physical Society

Scaling of the quark-antiquark potential and improved actions in SU(2) lattice gauge theory

International Nuclear Information System (INIS)

Montvay, I.; Gutbrod, F.

1983-11-01

The scaling behaviour of the quark-antiquark potential is investigated by a high statistics Monte Carlo calculation in SU(2) lattice gauge theory. Besides the standard one-plaquette action we also use Symanzik's tree-level improved action and Wilson's block-spin improved action. No significant differences between Symanzik's action and the standard action have been observed. For small β Wilson's action scales differently. The string tension value chi extracted from the data corresponds to Λsub(latt) = (0.018 +- 0.001) √chi for the one-plaquette action. (orig.)

Voxel Scale Complex Networks of Functional Connectivity in the Rat Brain: Neurochemical State Dependence of Global and Local Topological Properties

Directory of Open Access Journals (Sweden)

Adam J. Schwarz

2012-01-01

Full Text Available Network analysis of functional imaging data reveals emergent features of the brain as a function of its topological properties. However, the brain is not a homogeneous network, and the dependence of functional connectivity parameters on neuroanatomical substrate and parcellation scale is a key issue. Moreover, the extent to which these topological properties depend on underlying neurochemical changes remains unclear. In the present study, we investigated both global statistical properties and the local, voxel-scale distribution of connectivity parameters of the rat brain. Different neurotransmitter systems were stimulated by pharmacological challenge (d-amphetamine, fluoxetine, and nicotine to discriminate between stimulus-specific functional connectivity and more general features of the rat brain architecture. Although global connectivity parameters were similar, mapping of local connectivity parameters at high spatial resolution revealed strong neuroanatomical dependence of functional connectivity in the rat brain, with clear differentiation between the neocortex and older brain regions. Localized foci of high functional connectivity independent of drug challenge were found in the sensorimotor cortices, consistent with the high neuronal connectivity in these regions. Conversely, the topological properties and node roles in subcortical regions varied with neurochemical state and were dependent on the specific dynamics of the different functional processes elicited.

Scale-free, axisymmetry galaxy models with little angular momentum

International Nuclear Information System (INIS)

Richstone, D.O.

1980-01-01

Two scale-free models of elliptical galaxies are constructed using a self-consistent field approach developed by Schwarschild. Both models have concentric, oblate spheroidal, equipotential surfaces, with a logarithmic potential dependence on central distance. The axial ratio of the equipotential surfaces is 4:3, and the extent ratio of density level surfaces id 2.5:1 (corresponding to an E6 galaxy). Each model satisfies the Poisson and steady state Boltzmann equaion for time scales of order 100 galactic years

Scale-dependence of transverse momentum correlations in Pb sbnd Au collisions at 158A GeV/c

Science.gov (United States)

Adamová, D.; Agakichiev, G.; Antończyk, D.; Appelshäuser, H.; Belaga, V.; Bielcikova, S.; Braun-Munzinger, P.; Busch, O.; Cherlin, A.; Damjanović, S.; Dietel, T.; Dietrich, L.; Drees, A.; Dubitzky, W.; Esumi, S. I.; Filimonov, K.; Fomenko, K.; Fraenkel, Z.; Garabatos, C.; Glässel, P.; Holeczek, J.; Kushpil, V.; Maas, A.; Marín, A.; Milošević, J.; Milov, A.; Miśkowiec, D.; Panebrattsev, Yu.; Petchenova, O.; Petráček, V.; Pfeiffer, A.; Płoskoń, M.; Radomski, S.; Rak, J.; Ravinovich, I.; Rehak, P.; Sako, H.; Schmitz, W.; Sedykh, S.; Shimansky, S.; Stachel, J.; Šumbera, M.; Tilsner, H.; Tserruya, I.; Tsiledakis, G.; Wessels, J. P.; Wienold, T.; Wurm, J. P.; Xie, W.; Yurevich, S.; Yurevich, V.; Ceres Collaboration

2008-10-01

We present results on transverse momentum correlations of charged particle pairs produced in Pb sbnd Au collisions at 158A GeV/c at the Super Proton Synchrotron. The transverse momentum correlations have been studied as a function of collision centrality, angular separation of the particle pairs, transverse momentum and charge sign. We demonstrate that the results are in agreement with previous findings in scale-independent analyses at the same beam energy. Employing the two-particle momentum correlator and the cumulative p variable x(p), we identify, using the scale-dependent approach presented in this paper, different sources contributing to the measured correlations, such as quantum and Coulomb correlations, elliptic flow and mini-jet fragmentation.

Clausius-Clapeyron Scaling of Convective Available Potential Energy (CAPE) in Cloud-Resolving Simulations

Science.gov (United States)

Seeley, J.; Romps, D. M.

2015-12-01

Recent work by Singh and O'Gorman has produced a theory for convective available potential energy (CAPE) in radiative-convective equilibrium. In this model, the atmosphere deviates from a moist adiabat—and, therefore, has positive CAPE—because entrainment causes evaporative cooling in cloud updrafts, thereby steepening their lapse rate. This has led to the proposal that CAPE increases with global warming because the strength of evaporative cooling scales according to the Clausius-Clapeyron (CC) relation. However, CAPE could also change due to changes in cloud buoyancy and changes in the entrainment rate, both of which could vary with global warming. To test the relative importance of changes in CAPE due to CC scaling of evaporative cooling, changes in cloud buoyancy, and changes in the entrainment rate, we subject a cloud-resolving model to a suite of natural (and unnatural) forcings. We find that CAPE changes are primarily driven by changes in the strength of evaporative cooling; the effect of changes in the entrainment rate and cloud buoyancy are comparatively small. This builds support for CC scaling of CAPE.

Size-dependent error of the density functional theory ionization potential in vacuum and solution.

Science.gov (United States)

Sosa Vazquez, Xochitl A; Isborn, Christine M

2015-12-28

Density functional theory is often the method of choice for modeling the energetics of large molecules and including explicit solvation effects. It is preferable to use a method that treats systems of different sizes and with different amounts of explicit solvent on equal footing. However, recent work suggests that approximate density functional theory has a size-dependent error in the computation of the ionization potential. We here investigate the lack of size-intensivity of the ionization potential computed with approximate density functionals in vacuum and solution. We show that local and semi-local approximations to exchange do not yield a constant ionization potential for an increasing number of identical isolated molecules in vacuum. Instead, as the number of molecules increases, the total energy required to ionize the system decreases. Rather surprisingly, we find that this is still the case in solution, whether using a polarizable continuum model or with explicit solvent that breaks the degeneracy of each solute, and we find that explicit solvent in the calculation can exacerbate the size-dependent delocalization error. We demonstrate that increasing the amount of exact exchange changes the character of the polarization of the solvent molecules; for small amounts of exact exchange the solvent molecules contribute a fraction of their electron density to the ionized electron, but for larger amounts of exact exchange they properly polarize in response to the cationic solute. In vacuum and explicit solvent, the ionization potential can be made size-intensive by optimally tuning a long-range corrected hybrid functional.

Advances in cell culture: anchorage dependence

Science.gov (United States)

Merten, Otto-Wilhelm

2015-01-01

Anchorage-dependent cells are of great interest for various biotechnological applications. (i) They represent a formidable production means of viruses for vaccination purposes at very large scales (in 1000–6000 l reactors) using microcarriers, and in the last decade many more novel viral vaccines have been developed using this production technology. (ii) With the advent of stem cells and their use/potential use in clinics for cell therapy and regenerative medicine purposes, the development of novel culture devices and technologies for adherent cells has accelerated greatly with a view to the large-scale expansion of these cells. Presently, the really scalable systems—microcarrier/microcarrier-clump cultures using stirred-tank reactors—for the expansion of stem cells are still in their infancy. Only laboratory scale reactors of maximally 2.5 l working volume have been evaluated because thorough knowledge and basic understanding of critical issues with respect to cell expansion while retaining pluripotency and differentiation potential, and the impact of the culture environment on stem cell fate, etc., are still lacking and require further studies. This article gives an overview on critical issues common to all cell culture systems for adherent cells as well as specifics for different types of stem cells in view of small- and large-scale cell expansion and production processes. PMID:25533097

A space and time scale-dependent nonlinear geostatistical approach for downscaling daily precipitation and temperature

KAUST Repository

Jha, Sanjeev Kumar

2015-07-21

A geostatistical framework is proposed to downscale daily precipitation and temperature. The methodology is based on multiple-point geostatistics (MPS), where a multivariate training image is used to represent the spatial relationship between daily precipitation and daily temperature over several years. Here, the training image consists of daily rainfall and temperature outputs from the Weather Research and Forecasting (WRF) model at 50 km and 10 km resolution for a twenty year period ranging from 1985 to 2004. The data are used to predict downscaled climate variables for the year 2005. The result, for each downscaled pixel, is daily time series of precipitation and temperature that are spatially dependent. Comparison of predicted precipitation and temperature against a reference dataset indicates that both the seasonal average climate response together with the temporal variability are well reproduced. The explicit inclusion of time dependence is explored by considering the climate properties of the previous day as an additional variable. Comparison of simulations with and without inclusion of time dependence shows that the temporal dependence only slightly improves the daily prediction because the temporal variability is already well represented in the conditioning data. Overall, the study shows that the multiple-point geostatistics approach is an efficient tool to be used for statistical downscaling to obtain local scale estimates of precipitation and temperature from General Circulation Models. This article is protected by copyright. All rights reserved.

Anaerobic Digestion and Biogas Potential: Simulation of Lab and Industrial-Scale Processes

Directory of Open Access Journals (Sweden)

Ihsan Hamawand

2015-01-01

Full Text Available In this study, a simulation was carried out using BioWin 3.1 to test the capability of the software to predict the biogas potential for two different anaerobic systems. The two scenarios included: (1 a laboratory-scale batch reactor; and (2 an industrial-scale anaerobic continuous lagoon digester. The measured data related to the operating conditions, the reactor design parameters and the chemical properties of influent wastewater were entered into BioWin. A sensitivity analysis was carried out to identify the sensitivity of the most important default parameters in the software’s models. BioWin was then calibrated by matching the predicted data with measured data and used to simulate other parameters that were unmeasured or deemed uncertain. In addition, statistical analyses were carried out using evaluation indices, such as the coefficient of determination (R-squared, the correlation coefficient (r and its significance (p-value, the general standard deviation (SD and the Willmott index of agreement, to evaluate the agreement between the software prediction and the measured data. The results have shown that after calibration, BioWin can be used reliably to simulate both small-scale batch reactors and industrial-scale digesters with a mean absolute percentage error (MAPE of less than 10% and very good values of the indexes. Furthermore, by changing the default parameters in BioWin, which is a way of calibrating the models in the software, as well, this may provide information about the performance of the digester. Furthermore, the results of this study showed there may be an over estimation for biogas generated from industrial-scale digesters. More sophisticated analytical devices may be required for reliable measurements of biogas quality and quantity.

The relation between degree-2160 spectral models of Earth's gravitational and topographic potential: a guide on global correlation measures and their dependency on approximation effects

Science.gov (United States)

Hirt, Christian; Rexer, Moritz; Claessens, Sten; Rummel, Reiner

2017-10-01

Comparisons between high-degree models of the Earth's topographic and gravitational potential may give insight into the quality and resolution of the source data sets, provide feedback on the modelling techniques and help to better understand the gravity field composition. Degree correlations (cross-correlation coefficients) or reduction rates (quantifying the amount of topographic signal contained in the gravitational potential) are indicators used in a number of contemporary studies. However, depending on the modelling techniques and underlying levels of approximation, the correlation at high degrees may vary significantly, as do the conclusions drawn. The present paper addresses this problem by attempting to provide a guide on global correlation measures with particular emphasis on approximation effects and variants of topographic potential modelling. We investigate and discuss the impact of different effects (e.g., truncation of series expansions of the topographic potential, mass compression, ellipsoidal versus spherical approximation, ellipsoidal harmonic coefficient versus spherical harmonic coefficient (SHC) representation) on correlation measures. Our study demonstrates that the correlation coefficients are realistic only when the model's harmonic coefficients of a given degree are largely independent of the coefficients of other degrees, permitting degree-wise evaluations. This is the case, e.g., when both models are represented in terms of SHCs and spherical approximation (i.e. spherical arrangement of field-generating masses). Alternatively, a representation in ellipsoidal harmonics can be combined with ellipsoidal approximation. The usual ellipsoidal approximation level (i.e. ellipsoidal mass arrangement) is shown to bias correlation coefficients when SHCs are used. Importantly, gravity models from the International Centre for Global Earth Models (ICGEM) are inherently based on this approximation level. A transformation is presented that enables a

Fermionic particles with positron-dependent mass in the presence of inversely quadratic Yukawa potential and tensor interaction

International Nuclear Information System (INIS)

Bahar, M.K.; Yasuk, F.

2013-01-01

Approximate solutions of the Dirac equation with positron-dependent mass are presented for the inversely quadratic Yukawa potential and Coulomb-like tensor interaction by using the asymptotic iteration method. The energy eigenvalues and the corresponding normalized eigenfunctions are obtained in the case of positron-dependent mass and arbitrary spin-orbit quantum number k state and approximation on the spin-orbit coupling term. (author)

A scale-entropy diffusion equation to describe the multi-scale features of turbulent flames near a wall

Science.gov (United States)

Queiros-Conde, D.; Foucher, F.; Mounaïm-Rousselle, C.; Kassem, H.; Feidt, M.

2008-12-01

Multi-scale features of turbulent flames near a wall display two kinds of scale-dependent fractal features. In scale-space, an unique fractal dimension cannot be defined and the fractal dimension of the front is scale-dependent. Moreover, when the front approaches the wall, this dependency changes: fractal dimension also depends on the wall-distance. Our aim here is to propose a general geometrical framework that provides the possibility to integrate these two cases, in order to describe the multi-scale structure of turbulent flames interacting with a wall. Based on the scale-entropy quantity, which is simply linked to the roughness of the front, we thus introduce a general scale-entropy diffusion equation. We define the notion of “scale-evolutivity” which characterises the deviation of a multi-scale system from the pure fractal behaviour. The specific case of a constant “scale-evolutivity” over the scale-range is studied. In this case, called “parabolic scaling”, the fractal dimension is a linear function of the logarithm of scale. The case of a constant scale-evolutivity in the wall-distance space implies that the fractal dimension depends linearly on the logarithm of the wall-distance. We then verified experimentally, that parabolic scaling represents a good approximation of the real multi-scale features of turbulent flames near a wall.

Evaluating Potential Human Health Risks Associated with the Development of Utility-Scale Solar Energy Facilities on Contaminated Sites

Energy Technology Data Exchange (ETDEWEB)

Cheng, J. -J. [Argonne National Lab. (ANL), Argonne, IL (United States); Chang, Y. -S. [Argonne National Lab. (ANL), Argonne, IL (United States); Hartmann, H. [Argonne National Lab. (ANL), Argonne, IL (United States); Wescott, K. [Argonne National Lab. (ANL), Argonne, IL (United States); Kygeris, C. [Indiana Univ. of Pennsylvania, PA (United States)

2013-09-01

This report presents a general methodology for obtaining preliminary estimates of the potential human health risks associated with developing a utility-scale solar energy facility on a contaminated site, based on potential exposures to contaminants in soils (including transport of those contaminants into the air).

Short communication: Multi-scale topographic anisotropy patterns on a Barrier Island

Science.gov (United States)

Houser, Chris; Bishop, Michael; Wernette, Phil

2017-11-01

Barrier islands exhibit a range of landforms that reflect the complex and varied combination of coastal and aeolian processes realized over the evolution of the island. A detailed analysis of the topography can be used to describe the evolution of a barrier island and provide insight on how it may be affected by a change in sea level, storm activity and wind exposure patterns. Topographic anisotropy, or the directional dependence of relief of landforms, can be used to determine the relative importance of different processes to island evolution at a range of scales. This short communication describes the use of scale-dependent topographic anisotropy to characterize the structure of Santa Rosa Island in northwest Florida. Scale-dependent topographic relief and asymmetry were assessed from a LiDAR-derived DEM from May 2004, a few months before the island experienced widespread erosion and overwash during Hurricane Ivan. This application demonstrates how anisotropy can be used to identify unique scale-dependent structures that can be used to interpret the evolution of this barrier island. Results of this preliminary study further highlight the potential of using topographic anisotropy to controls on barrier island response and recovery to storms as well as island resiliency with sea level rise and storm activity.

Context-dependent encoding of fear and extinction memories in a large-scale network model of the basal amygdala.

Science.gov (United States)

Vlachos, Ioannis; Herry, Cyril; Lüthi, Andreas; Aertsen, Ad; Kumar, Arvind

2011-03-01

The basal nucleus of the amygdala (BA) is involved in the formation of context-dependent conditioned fear and extinction memories. To understand the underlying neural mechanisms we developed a large-scale neuron network model of the BA, composed of excitatory and inhibitory leaky-integrate-and-fire neurons. Excitatory BA neurons received conditioned stimulus (CS)-related input from the adjacent lateral nucleus (LA) and contextual input from the hippocampus or medial prefrontal cortex (mPFC). We implemented a plasticity mechanism according to which CS and contextual synapses were potentiated if CS and contextual inputs temporally coincided on the afferents of the excitatory neurons. Our simulations revealed a differential recruitment of two distinct subpopulations of BA neurons during conditioning and extinction, mimicking the activation of experimentally observed cell populations. We propose that these two subgroups encode contextual specificity of fear and extinction memories, respectively. Mutual competition between them, mediated by feedback inhibition and driven by contextual inputs, regulates the activity in the central amygdala (CEA) thereby controlling amygdala output and fear behavior. The model makes multiple testable predictions that may advance our understanding of fear and extinction memories.

Context-dependent encoding of fear and extinction memories in a large-scale network model of the basal amygdala.

Directory of Open Access Journals (Sweden)

Ioannis Vlachos

2011-03-01

Full Text Available The basal nucleus of the amygdala (BA is involved in the formation of context-dependent conditioned fear and extinction memories. To understand the underlying neural mechanisms we developed a large-scale neuron network model of the BA, composed of excitatory and inhibitory leaky-integrate-and-fire neurons. Excitatory BA neurons received conditioned stimulus (CS-related input from the adjacent lateral nucleus (LA and contextual input from the hippocampus or medial prefrontal cortex (mPFC. We implemented a plasticity mechanism according to which CS and contextual synapses were potentiated if CS and contextual inputs temporally coincided on the afferents of the excitatory neurons. Our simulations revealed a differential recruitment of two distinct subpopulations of BA neurons during conditioning and extinction, mimicking the activation of experimentally observed cell populations. We propose that these two subgroups encode contextual specificity of fear and extinction memories, respectively. Mutual competition between them, mediated by feedback inhibition and driven by contextual inputs, regulates the activity in the central amygdala (CEA thereby controlling amygdala output and fear behavior. The model makes multiple testable predictions that may advance our understanding of fear and extinction memories.

The Predictive Role of Difficulties in Emotion Regulation and Self-Control with Susceptibility to Addiction in Drug-Dependent Individuals

Directory of Open Access Journals (Sweden)

Mahmoud Shirazi

2015-06-01

Full Text Available Objective: The present study aimed to examine the predictive role of difficulties in emotion regulation and self-control in potential for addiction among drug-dependent individuals. Method: This was a correlational study which falls within the category of descriptive studies. The statistical population of the current study included all patients under treatment in outpatient health centers in Bam, among whom 315 individuals were selected through cluster sampling method as the participants of the study. Difficulties in Emotion Regulation Scale, Self-Control Scale, and Addiction Susceptibility Questionnaire were used for data collection purposes. Results: The results indicated that difficulties engaging in goal directed behavior, impulse control difficulties, lack of emotional awareness, and lack of emotional clarity (dimensions of difficulties in emotion regulation had a significant positive correlation with potential for addiction. In addition, there was a negative significant relationship between self-control and potential for addiction among drug-dependent individuals. Conclusion: In addition to common methods of abstinence from drug dependence, teaching self-control and emotional control techniques to addicted patients can help them reduce their dependence.

Time-dependent scaling patterns in high frequency financial data

Science.gov (United States)

Nava, Noemi; Di Matteo, Tiziana; Aste, Tomaso

2016-10-01

We measure the influence of different time-scales on the intraday dynamics of financial markets. This is obtained by decomposing financial time series into simple oscillations associated with distinct time-scales. We propose two new time-varying measures of complexity: 1) an amplitude scaling exponent and 2) an entropy-like measure. We apply these measures to intraday, 30-second sampled prices of various stock market indices. Our results reveal intraday trends where different time-horizons contribute with variable relative amplitudes over the course of the trading day. Our findings indicate that the time series we analysed have a non-stationary multifractal nature with predominantly persistent behaviour at the middle of the trading session and anti-persistent behaviour at the opening and at the closing of the session. We demonstrate that these patterns are statistically significant, robust, reproducible and characteristic of each stock market. We argue that any modelling, analytics or trading strategy must take into account these non-stationary intraday scaling patterns.

Inflation in random landscapes with two energy scales

Science.gov (United States)

Blanco-Pillado, Jose J.; Vilenkin, Alexander; Yamada, Masaki

2018-02-01

We investigate inflation in a multi-dimensional landscape with a hierarchy of energy scales, motivated by the string theory, where the energy scale of Kahler moduli is usually assumed to be much lower than that of complex structure moduli and dilaton field. We argue that in such a landscape, the dynamics of slow-roll inflation is governed by the low-energy potential, while the initial condition for inflation are determined by tunneling through high-energy barriers. We then use the scale factor cutoff measure to calculate the probability distribution for the number of inflationary e-folds and the amplitude of density fluctuations Q, assuming that the low-energy landscape is described by a random Gaussian potential with a correlation length much smaller than M pl. We find that the distribution for Q has a unique shape and a preferred domain, which depends on the parameters of the low-energy landscape. We discuss some observational implications of this distribution and the constraints it imposes on the landscape parameters.

Preliminary investigations of potential light weight metallic armour applications

NARCIS (Netherlands)

Voorde, M.J. van de; Diederen, A.M.; Herlaar, K.

2005-01-01

Now that an industrial-scale low-cost production route for ballistic-grade titanium is within reach, the potential use of titanium armour could depend on a solution for the spalling of high strength titanium. This paper addresses a titanium based metal laminate as being a possible solution for the

Ataxia rating scales are age-dependent in healthy children

NARCIS (Netherlands)

Brandsma, Rick; Spits, Anne H.; Kuiper, Marieke J.; Lunsing, Roelinka J.; Burger, Huibert; Kremer, Hubertus P.; Sival, Deborah A.

AIM: To investigate ataxia rating scales in children for reliability and the effect of age and sex. METHOD: Three independent neuropaediatric observers cross-sectionally scored a set of paediatric ataxia rating scales in a group of 52 healthy children (26 males, 26 females) aged 4 to 16 years (mean

Absence of both auditory evoked potentials and auditory percepts dependent on timing cues.

Science.gov (United States)

Starr, A; McPherson, D; Patterson, J; Don, M; Luxford, W; Shannon, R; Sininger, Y; Tonakawa, L; Waring, M

1991-06-01

An 11-yr-old girl had an absence of sensory components of auditory evoked potentials (brainstem, middle and long-latency) to click and tone burst stimuli that she could clearly hear. Psychoacoustic tests revealed a marked impairment of those auditory perceptions dependent on temporal cues, that is, lateralization of binaural clicks, change of binaural masked threshold with changes in signal phase, binaural beats, detection of paired monaural clicks, monaural detection of a silent gap in a sound, and monaural threshold elevation for short duration tones. In contrast, auditory functions reflecting intensity or frequency discriminations (difference limens) were only minimally impaired. Pure tone audiometry showed a moderate (50 dB) bilateral hearing loss with a disproportionate severe loss of word intelligibility. Those auditory evoked potentials that were preserved included (1) cochlear microphonics reflecting hair cell activity; (2) cortical sustained potentials reflecting processing of slowly changing signals; and (3) long-latency cognitive components (P300, processing negativity) reflecting endogenous auditory cognitive processes. Both the evoked potential and perceptual deficits are attributed to changes in temporal encoding of acoustic signals perhaps occurring at the synapse between hair cell and eighth nerve dendrites. The results from this patient are discussed in relation to previously published cases with absent auditory evoked potentials and preserved hearing.

Temperature dependence of fluctuation time scales in spin glasses

DEFF Research Database (Denmark)

Kenning, Gregory G.; Bowen, J.; Sibani, Paolo

2010-01-01

Using a series of fast cooling protocols we have probed aging effects in the spin glass state as a function of temperature. Analyzing the logarithmic decay found at very long time scales within a simple phenomenological barrier model, leads to the extraction of the fluctuation time scale of the s...