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1

SimSphere model sensitivity analysis towards establishing its use for deriving key parameters characterising land surface interactions  

NASA Astrophysics Data System (ADS)

Being able to accurately estimate parameters characterising land surface interactions is currently a key scientific priority due to their central role in the Earth's global energy and water cycle. To this end, some approaches have been based on utilising the synergies between land surface models and Earth observation (EO) data to retrieve relevant parameters. One such model is SimSphere, the use of which is currently expanding, either as a stand-alone application or synergistically with EO data. The present study aimed at exploring the effect of changing the atmospheric sounding profile on the sensitivity of key variables predicted by this model assuming different probability distribution functions (PDFs) for its inputs/outputs. To satisfy this objective and to ensure consistency and comparability to analogous studies conducted previously on the model, a sophisticated, cutting-edge sensitivity analysis (SA) method adopting Bayesian theory was implemented on SimSphere. Our results did not show dramatic changes in the nature or ranking of influential model inputs in comparison to previous studies. Model outputs examined using SA were sensitive to a small number of the inputs; a significant amount of first-order interactions between the inputs was also found, suggesting strong model coherence. Results showed that the assumption of different PDFs for the model inputs/outputs did not have an important bearing on mapping the most responsive model inputs and interactions, but only the absolute SA measures. This study extends our understanding of SimSphere's structure and further establishes its coherence and correspondence to that of a natural system's behaviour. Consequently, the present work represents a significant step forward in the global efforts on SimSphere verification, especially those focusing on the development of global operational products from the model synergy with EO data.

Petropoulos, G. P.; Griffiths, H. M.; Carlson, T. N.; Ioannou-Katidis, P.; Holt, T.

2014-09-01

2

Radiative $?$ decays with derivative interactions  

E-print Network

We study the line shapes of radiative $\\phi$-decays involving virtual $f_{0}(980)$ and $a_{0}(980)$ mesons which decay, via derivative couplings, to $\\pi^{0}\\pi^{0}$ and $\\pi^{0}\\eta$ respectively. After developing the formalism for derivative interactions at one-loop level, we show that they can reproduce the measured peaked line shapes of $\\phi$-decays without including kaon loops.

Francesco Giacosa; Giuseppe Pagliara

2008-04-09

3

Perturbative unitarity of Higgs derivative interactions  

NASA Astrophysics Data System (ADS)

We study the perturbative unitarity bound given by dimension six derivative interactions consisting of Higgs doublets. These interactions emerge from kinetic terms of composite Higgs models or integrating out heavy particles that interact with Higgs doublets. They lead to new phenomena beyond the Standard Model. One of characteristic contributions from derivative interactions appear in vector boson scattering processes. Longitudinal modes of massive vector bosons can be regarded as Nambu Goldstone bosons eaten by each vector field. Since their effects become larger and larger as the collision energy of vector bosons increases, vector boson scattering processes become important in the high energy region around the TeV scale. On the other hand, in such a high energy region, we have to take into account the unitarity of amplitudes. We have obtained the unitarity condition in terms of the parameter included in the effective Lagrangian for one Higgs doublet models. Applying it to some models, we have found that contributions of derivative interactions are not so large enough to clearly discriminate them from the Standard Model ones. We also study the unitarity bound in two Higgs doublet models. Because they are too complex to obtain it in the general effective Lagrangian, we have calculated it in explicit models. These analyses tell that the perturbative unitarity bounds are highly model dependent.

Kikuta, Yohei; Yamamoto, Yasuhiro

2013-05-01

4

Gruneisen parameter: measurement of the strain derivatives  

Microsoft Academic Search

The derivatives of non-linear coupling coefficients in the Taylor expansion of thermodynamic potentials should play a major role in solids driven off equilibrium. A measurement is described of the derivatives of the Gruneisen thermomechanical state function gamma with respect to the imposed tensile deformation epsilon *. For alpha -Ti, these derivatives are found to be delta gamma \\/ delta epsilon

C. E. Bottani; G. Caglioti; P. M. Ossi

1981-01-01

5

Application of Statistically Derived CPAS Parachute Parameters  

NASA Technical Reports Server (NTRS)

The Capsule Parachute Assembly System (CPAS) Analysis Team is responsible for determining parachute inflation parameters and dispersions that are ultimately used in verifying system requirements. A model memo is internally released semi-annually documenting parachute inflation and other key parameters reconstructed from flight test data. Dispersion probability distributions published in previous versions of the model memo were uniform because insufficient data were available for determination of statistical based distributions. Uniform distributions do not accurately represent the expected distributions since extreme parameter values are just as likely to occur as the nominal value. CPAS has taken incremental steps to move away from uniform distributions. Model Memo version 9 (MMv9) made the first use of non-uniform dispersions, but only for the reefing cutter timing, for which a large number of sample was available. In order to maximize the utility of the available flight test data, clusters of parachutes were reconstructed individually starting with Model Memo version 10. This allowed for statistical assessment for steady-state drag area (CDS) and parachute inflation parameters such as the canopy fill distance (n), profile shape exponent (expopen), over-inflation factor (C(sub k)), and ramp-down time (t(sub k)) distributions. Built-in MATLAB distributions were applied to the histograms, and parameters such as scale (sigma) and location (mu) were output. Engineering judgment was used to determine the "best fit" distribution based on the test data. Results include normal, log normal, and uniform (where available data remains insufficient) fits of nominal and failure (loss of parachute and skipped stage) cases for all CPAS parachutes. This paper discusses the uniform methodology that was previously used, the process and result of the statistical assessment, how the dispersions were incorporated into Monte Carlo analyses, and the application of the distributions in trajectory benchmark testing assessments with parachute inflation parameters, drag area, and reefing cutter timing used by CPAS.

Romero, Leah M.; Ray, Eric S.

2013-01-01

6

Five-parameter fractional derivative model for polymeric damping materials  

Microsoft Academic Search

Fractional derivative models offer a powerful tool to describe the dynamic behaviour of real viscoelastic materials. A version of the fractional derivative models characterized by five parameters is presented and investigated in this paper in order to describe asymmetrical loss factor peak and the high-frequency behaviour of polymeric damping materials. The speculative derivation of the model constitutive equation containing time

T. Pritz

2003-01-01

7

Isothermal volume derivative of thermodynamic Gruneisen parameter, nonlinearity parameter and intermolecular heat capacity of liquids  

Microsoft Academic Search

The isochoric temperature derivative of Sound Velocity, the isothermal volume derivative of thermodynamic Gruneisen parameter, fractional free (available) volume and the repulsive exponent of intermolecular potential are shown to be related to t he microscopic Gruneisen parameter and Beyer's nonlinearity parameter of the liquid, The intermolecular contributions to the heat capacity and the adiabatic bulk modulw have been evaluated from

B. K. SHARMA

1994-01-01

8

Derivative interactions for a spin-2 field at cubic order  

NASA Astrophysics Data System (ADS)

Lorentz invariant derivative interactions for a single spin-2 field are investigated, up to the cubic order. We start from the most general Lorentz invariant terms involving two spacetime derivatives, which are polynomials in the spin-2 field as well as its first derivatives. Using a perturbative Arnowitt-Deser-Misner analysis, we determined the parameters such that the corresponding Hamiltonian possesses a Lagrange multiplier, which would signify there are at most 5 degrees of freedom that are propagating. The resulting derivative terms are linear combinations of terms coming from the expansion of the Einstein-Hilbert Lagrangian around a Minkowski background, as well as the cubic "pseudolinear derivative term" identified in Hinterbichler [J. High Energy Phys. 10 (2013) 102]. We also derived the compatible potential terms, which are linear combinations of the expansions of the first two de Rham-Gabadadze-Tolley mass terms in unitary gauge.

Gao, Xian

2014-09-01

9

Final-state interactions and neutron-neutron scattering parameters  

Microsoft Academic Search

A method is presented to extend the calculations of McVoy and Bander to determine the low-energy neutron-neutron scattering parameters from the spectrum of the reaction pi-+d-->2n+gamma. The transition amplitude for the capture reaction is derived in the impulse approximation and is related to 12 rotationally invariant amplitudes. The final-state interactions between the two neutrons are treated by means of dispersion

G. F. de Téramond

1977-01-01

10

Comparison of methods for deriving aerosol asymmetry parameter  

Microsoft Academic Search

Values for Mie-equivalent aerosol asymmetry parameter (g) were derived using a variety of methods from the large suite of measurements (in situ and remote from surface and aircraft) made in Oklahoma during the 2003 aerosol Intensive Operations Period (IOP). Median values derived for dry asymmetry parameter at 550 nm ranged between 0.55 and 0.63 over all instruments and for all

E. Andrews; P. J. Sheridan; M. Fiebig; A. McComiskey; J. A. Ogren; P. Arnott; D. Covert; R. Elleman; R. Gasparini; D. Collins; H. Jonsson; B. Schmid; J. Wang

2006-01-01

11

Instantaneous phase and frequency derived without user-defined parameters  

NASA Astrophysics Data System (ADS)

We define an algorithm in the time domain for computing the unwrapped instantaneous phase and its derivative, the instantaneous frequency, using only derivatives and integrals. It does not require user-defined parameters, like most algorithms proposed so far. We validate and compare its performance with respect to open-source and commercial software by synthetic and real data examples.

Poggiagliolmi, E.; Vesnaver, A.

2014-12-01

12

Comparison of Derived Stellar Parameters for LAMOST and SEGUE Spectra  

Microsoft Academic Search

We have derived estimates of stellar atmospheric parameters (Teff, log g, [Fe\\/H]) for more than 1000 stars with medium-resolution spectra (R = 1800) observed by both SDSS\\/SEGUE and the LAMOST (Guoshoujing) Telescope. The spectra have been analysed by the current version of the SEGUE Stellar Parameter Pipeline (Lee et al. 2008a, Allende Prieto et al. 2008, Smolinski et al. 2010).

Jeffrey L. Carlin; H. J. Newberg; T. C. Beers; Y. S. Lee; B. Yanny; L. Deng; H. Zhang; G. Zhao; Y. Zhang; A. Luo; J. Chen; Z. Bai; G. Li

2011-01-01

13

ATMOSPHERIC INSTABILITY PARAMETERS DERIVED FROM MSG SEVIRI OBSERVATIONS  

Microsoft Academic Search

Within the MSG Global Instability Index (GII) product, information on the static stability and other airmass parameters will be operationally derived and disseminated. The GII product should serve as a nowcasting tool to identify the potential of convection and possibly of severe storms in still preconvective conditions. The applied retrieval method makes use of six MSG SEVIRI thermal bands, and

Marianne König; Stephen Tjemkes; Jochen Kerkmann

14

Relationships between derivative spectra and agronomic parameters of corn  

Microsoft Academic Search

The objective of this paper is to discuss the action of derivative spectra of corn in determining spectral bands that are best suited for characterizing corn agronomic parameters. The data for this study comes from filed and indoor reflectance measurements of corn by a ASD FieldSpec Pro FR. Observed corn characteristics included leaf area index, aboveground fresh biomass chlorophyll concentration

Qiuxiang Yi; Xiuzhen Wang; Jingfeng Huang; Yi Qian; Shanxian Yu

2004-01-01

15

Parameters, limits and higher derivative type II string corrections  

NASA Astrophysics Data System (ADS)

String theory in d dimensions has n + 1 = 11 - d parameters that may be thought of as being inherited from the geometry of an n + 1 torus which may be used to construct the theory using dimensional reduction from eleven dimensions. We give the precise relationship between these parameters and the expectation values of the scalar fields that parameterise the E n+1 coset of the d dimensional theory. This allows us to examine all possible limits of the automorphic forms which occur as the coefficient functions of the higher derivative corrections to the d dimensional type II string effective action.

Gubay, Finn; West, Peter

2012-11-01

16

Comparison of ionospheric peak parameters derived from different modeling approaches  

NASA Astrophysics Data System (ADS)

Due to the fact that Ionosphere is a dispersive medium, microwave signals travelling through this medium are affected proportional to their frequencies. This effect allows gaining information about the parameters of the ionosphere in terms of Total Electron Content (TEC) or the electron density. There are different approaches for modeling these parameters. Some models are based on physical properties such as the Global Assimilative Ionospheric Model (GAIM). Some are empirical models, e.g. the International Reference Ionosphere (IRI), the NeQuick model, or the Neustrelitz TEC Model (NTCM). Finally some models are based on purely mathematical/statistical approaches. In the mathematical models, the corresponding model parameters are calculated using measurements from different space geodetic techniques or the ionosonde data. This study investigates different approaches for computing the electron density along the ray path. First the mathematical approach developed at Technical University of Berlin (TUB) for global 3D reconstruction of the ionospheric F2-peak parameters is presented. In this approach, the F2-peak parameters, i.e. the maximum electron density and its corresponding height are represented as a function of geographic or geomagnetic longitude, latitude, and height with two sets of spherical harmonic expansions of degree and order 15, which correspond to a spatial resolution of 5° in longitude and 2.5° in latitude. To assess this modeling approach, the estimated F2-peak parameters are compared with the peak parameters derived from several other modeling approaches.

Mahdi Alizadeh, M.; Schuh, Harald

2014-05-01

17

Non-Linear derivative interactions in relativistic hadrodynamics  

E-print Network

The Lagrangian density of Relativistic Hadrodynamics (RHD) is extended by introducing non-linear derivative (NLD) interactions of the nucleon with the meson fields. As a consequence, the nucleon selfenergy becomes both momentum and density dependent. With a single cut-off parameter, which regulates the NLD Lagrangian, our approach is compatible with results from microscopic nuclear matter calculations as well as with Dirac phenomenology. It also reproduces the correct behavior of the real part of the proton-nucleus potential both at low and at high proton energies.

T. Gaitanos; M. Kaskulov; U. Mosel

2009-04-07

18

Analytic partial derivatives for estimating low-thrust parameters.  

NASA Technical Reports Server (NTRS)

Analytic partial derivatives for estimating orbital low-thrust parameters via differential correction are developed and compared with two different numerical methods. The formulation is independent of the particular thrust model used and is applicable to all physically possible elliptic orbits. The starting point for the development is the set of variational equations of the elliptic orbital elements in the form due to Lagrange. The first time derivatives of the elements are transformed to derivatives with respect to the space variable, true anomaly, and integrated to first order in closed form in a straightforward general perturbations approach, with one exception: particular attention is given to the mean anomaly as influenced by thrust perturbations in the semimajor axis so that the complete first-order effect is included. The partials of the elements are then taken with respect to any given thrust parameter. Two comparisons are made with numerical methods for computing these thrust partials: numerical quotients and numerical integration of the variational equations for thrust.

Cunningham, G. W.

1972-01-01

19

A study of photon interaction parameters in lung tissue substitutes  

PubMed Central

The study of photon interaction with different composite materials has become a topic of prime importance for radiation physicists. Some parameters of dosimetric interest are the mass attenuation coefficient, effective atomic number, and electron density; these help in the basic understanding of photon interactions with composite materials. The photon interaction parameters such as mass attenuation coefficient (?/?), effective atomic number (Zeff), and effective electron density (Nel) must be identical for the phantom material and their tissue. In the present study, we have evaluated the photon interaction parameters such as (?/?), Zeff and Nel of 13 lung tissue substitutes. The variations of these parameters of lung tissue substitutes with photon energy are graphically represented. The photon interaction parameters of lung tissue substitutes are compared with that of lung tissue. The variation of photon interaction parameters of the studied lung tissue substitutes is similar that of the lung. Logically, it can be shown that Alderson lung is good substitute for lung than the other substitutes. PMID:24872609

Manjunatha, H. C.

2014-01-01

20

Atmospheric Instability Parameters Derived from MSG SEVIRI Observations  

E-print Network

Within the MSG Global Instability Index (GII) product, information on the static stability and other airmass parameters will be operationally derived and disseminated. The GII product should serve as a nowcasting tool to identify the potential of convection and possibly of severe storms in still preconvective conditions. The applied retrieval method makes use of six MSG SEVIRI thermal bands, and together with the a priori information of forecast profiles, the scheme infers an updated atmospheric profile for each MSG pixel or superpixel location, from which instability indices can be computed. First applications to early MSG imagery show good agreement to co-located radiosonde data. A case is presented which shows the potential of the satellite retrieved instability parameter as a preconvective warning measure.

Marianne König

21

Satellite observation of atmosphere and surface interaction parameters  

NASA Technical Reports Server (NTRS)

Atmosphere and ocean surface parameters are being derived from weather satellite data acquired by the High Resolution Infrared Sounder and the Microwave Sounding Unit. In this paper, the global distribution and accuracy of the derived parameters are described, and the satellite-derived skin surface temperature is compared with available shelter temperature. Seasonal and interannual changes are examined to study the response time of large-scale atmospheric changes to changes in surface conditions.

Chahine, Moustafa T.; Haskins, Robert D.; Susskind, Joel; Reuter, Dennis

1987-01-01

22

Poisson equations, higher derivative automorphic forms and string parameter limits  

NASA Astrophysics Data System (ADS)

This paper considers the higher derivative terms in the effective action of type II string theory and in particular the behaviour of the automorphic forms they contain in all the different possible limits of the string parameters. The automorphic forms are thought to obey Poisson equations which contain the Laplacian defined on the coset space to which the scalars fields belong and we compute this Laplacian in all the possible string theory limits. We also consider these Poisson equations in the decompactification limit of a single dimension and by making two assumptions, one on the generic form of this equation and the other on the behaviour of the automorphic forms in this limit, we find strong constraints on the allowed form of this differential equation. We show that these constraints allow one to recover much of what was previously known about the automorphic forms corresponding to terms in the effective action that have fourteen or fewer space-time derivatives in a simple way.

Gubay, Finn; West, Peter

2014-06-01

23

Connection between dynamically derived IMF normalisation and stellar population parameters  

E-print Network

We report on empirical trends between the dynamically determined stellar initial mass function (IMF) and stellar population properties for a complete, volume-limited sample of 260 early-type galaxies from the Atlas3D project. We study trends between our dynamically-derived IMF normalisation and absorption line strengths, and interpret these via single stellar population- (SSP-) equivalent ages, abundance ratios (measured as [alpha/Fe]), and total metallicity, [Z/H]. We find that old and alpha-enhanced galaxies tend to have on average heavier (Salpeter-like) mass normalisation of the IMF, but stellar population does not appear to be a good predictor of the IMF, with a large range of normalisation at a given population parameter. As a result, we find weak IMF-[alpha/Fe] and IMF-age correlations, and no significant IMF-[Z/H] correlation. The observed trends appear significantly weaker than those reported in studies that measure the IMF normalisation via low-mass star demographics inferred through stellar spectra...

McDermid, Richard M; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frederic; Bureau, Martin; Crocker, Alison F; Davies, Roger L; Davis, Timothy A; de Zeeuw, P T; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnovic, Davor; Kuntschner, Harald; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M

2014-01-01

24

Effect of plasma surface interactions on PLT plasma parameters  

SciTech Connect

This paper gives a brief description of the geometry and parameters of the PLT tokamak, reviews some of the last four years' results that are particularly relevant to plasma-boundary interactions, and then concentrates on two specific problems.

Meservey, E.B.; Arunasalam, V.; Barnes, C.

1980-07-01

25

A study of photon interaction parameters in lung tissue substitutes.  

PubMed

The study of photon interaction with different composite materials has become a topic of prime importance for radiation physicists. Some parameters of dosimetric interest are the mass attenuation coefficient, effective atomic number, and electron density; these help in the basic understanding of photon interactions with composite materials. The photon interaction parameters such as mass attenuation coefficient (?/?), effective atomic number (Zeff), and effective electron density (N el) must be identical for the phantom material and their tissue. In the present study, we have evaluated the photon interaction parameters such as (?/?), Z eff and N el of 13 lung tissue substitutes. The variations of these parameters of lung tissue substitutes with photon energy are graphically represented. The photon interaction parameters of lung tissue substitutes are compared with that of lung tissue. The variation of photon interaction parameters of the studied lung tissue substitutes is similar that of the lung. Logically, it can be shown that Alderson lung is good substitute for lung than the other substitutes. PMID:24872609

Manjunatha, H C

2014-04-01

26

Validating a large geophysical data set: Experiences with satellite-derived cloud parameters  

NASA Technical Reports Server (NTRS)

We are validating the global cloud parameters derived from the satellite-borne HIRS2 and MSU atmospheric sounding instrument measurements, and are using the analysis of these data as one prototype for studying large geophysical data sets in general. The HIRS2/MSU data set contains a total of 40 physical parameters, filling 25 MB/day; raw HIRS2/MSU data are available for a period exceeding 10 years. Validation involves developing a quantitative sense for the physical meaning of the derived parameters over the range of environmental conditions sampled. This is accomplished by comparing the spatial and temporal distributions of the derived quantities with similar measurements made using other techniques, and with model results. The data handling needed for this work is possible only with the help of a suite of interactive graphical and numerical analysis tools. Level 3 (gridded) data is the common form in which large data sets of this type are distributed for scientific analysis. We find that Level 3 data is inadequate for the data comparisons required for validation. Level 2 data (individual measurements in geophysical units) is needed. A sampling problem arises when individual measurements, which are not uniformly distributed in space or time, are used for the comparisons. Standard 'interpolation' methods involve fitting the measurements for each data set to surfaces, which are then compared. We are experimenting with formal criteria for selecting geographical regions, based upon the spatial frequency and variability of measurements, that allow us to quantify the uncertainty due to sampling. As part of this project, we are also dealing with ways to keep track of constraints placed on the output by assumptions made in the computer code. The need to work with Level 2 data introduces a number of other data handling issues, such as accessing data files across machine types, meeting large data storage requirements, accessing other validated data sets, processing speed and throughput for interactive graphical work, and problems relating to graphical interfaces.

Kahn, Ralph; Haskins, Robert D.; Knighton, James E.; Pursch, Andrew; Granger-Gallegos, Stephanie

1992-01-01

27

Effects of Ignoring Item Interaction on Item Parameter Estimation and Detection of Interacting Items  

ERIC Educational Resources Information Center

This study explores the effects of ignoring item interaction on item parameter estimation and the efficiency of using the local dependence index Q[subscript 3] and the SAS NLMIXED procedure to detect item interaction under the three-parameter logistic model and the generalized partial credit model. Through simulations, it was found that ignoring…

Chen, Cheng-Te; Wang, Wen-Chung

2007-01-01

28

Faulting parameters derived from computer simulation of earthquakes  

NASA Technical Reports Server (NTRS)

Seismic source parameters, average displacement, rupture length, and strain energy release are investigated by computer simulation using a coupled massive block model of the sliding along an active fault. Average displacements and energy release vary considerably with the degree of heterogeneity in the friction and elastic parameters used in the model. Strain energy release is determined primarily by the product of dynamic friction, rupture length, and average displacement. Interrelationships among the faulting parameters are consistent with theoretical arguments and experimental data. The variation in the frequency of occurrence of simulation events with strain energy release is different from the variation in the frequency of naturally occurring events with seismic energy.

Cohen, S. C.

1977-01-01

29

Bulk Surface Momentum Parameters for Satellite-Derived Vegetation Fields  

NASA Technical Reports Server (NTRS)

The bulk aerodynamic parameters associated with the absorption of surface momentum by vegetated landscapes are theoretically estimated within the context of Raupach's roughness sublayer formulation. The parameters include the bulk plant drag coefficient, maximum u*/U(sub h), sheltering coefficient, and canopy area density at onset of sheltering. Parameters are estimated for the four principal IGBP land cover classes within the U.S. Southern Great Plains: evergreen needleleaf forests, grasslands, croplands, and open shrublands. The estimation approach applies the Method of Moments to roughness data from several international field experiments and other published sources. The results provide the necessary land surface parameters for satellite-based estimation of momentum aerodynamic roughness length and zero-plane displacement height for seasonally variable vegetation fields employed in most terrestrial and atmospheric simulation models used today. Construction of sample displacement and roughness maps over the Southern United States using MODIS land products demonstrates the potential of this approach for regional to global applications.

Jasinski, Michael F.; Borak, Jordan; Crago, Richard

2005-01-01

30

AC conductivity parameters of graphene derived from THz etalon transmittance.  

PubMed

THz frequency-domain transmittance measurements were carried out on chemical-vapor-deposited (CVD) graphene films transferred to high-resistivity silicon substrates, and packaged as back-gated graphene field effect transistors (G-FETs). The graphene AC conductivity ?(?), both real and imaginary parts, is determined between 0.2 and 1.2 THz from the transmittance using the transmission matrix method and curve-fitting techniques. Critical parameters such as the charge-impurity scattering width and chemical potential are calculated. It is found that not only the sheet charge density but also the scattering parameter can be modified by the back-gate voltage. PMID:25307168

Zhang, Weidong; H Q Pham, Phi; Brown, Elliott R; J Burke, Peter

2014-10-24

31

Structural and interaction parameters of thermosensitive native ?-elastin biohybrid microgel  

NASA Astrophysics Data System (ADS)

The structural and water interaction parameters for native, ?-elastin biohybrid microgel crosslinked with hydrophilic and hydrophobic crosslinkers are obtained from the volume phase transition temperature behaviour, 1H high-resolution magic-angle sample spinning transverse magnetization relaxation NMR, and modified Flory-Rehner swelling theory. Firstly, considering a homogeneous morphology the number of subchains in the biohybrid microgel, the residual water in deswollen state as a function of crosslink density and the temperature dependence of the Flory biopolymer-water interaction parameters are reported for the biohybrid microgels prepared with hydrophilic (PEG-DGE) and hydrophobic (BS3) crosslinkers. The Flory-Rehner classical approach is subsequently modified taking into account the heterogeneities observed by NMR transverse relaxation measurements. Two differently mobile regions are determined, a hydrophobic domain and a crosslinking domain with relative reduced mobility. For the first time, the influence of chain mobility on the Flory interaction parameter is investigated through a modified Flory state equation. The contributions of amino-acids located in the hydrophobic and crosslinking domains in the polypeptide sequence are separated while analyzing the biopolymer-water interaction.

Balaceanu, Andreea; Singh, Smriti; Demco, Dan E.; Möller, Martin

2014-09-01

32

Three-parameter tunable Tilt-Integral-Derivative (TID) controller  

NASA Technical Reports Server (NTRS)

A feedback control system compensator of the PID type is provided, wherein the proportional component of the compensator is replaced with a tilted component having a transfer function s to the power of -1/n. The resulting transfer function of the entire compensator more closely approximates an optimal transfer function, thereby achieving improved feedback controller. Further, as compared to conventional PID compensators, the TID compensator allows for simpler tuning, better disturbance rejection ratio, and smaller effects of plant parameter variations on closed loop response.

Lurie, Boris J. (inventor)

1994-01-01

33

Supramolecular Interactions of Terpyridine-Derived Cores of Metallomesogen Precursors  

PubMed Central

Use of Hirshfeld surfaces calculated from crystal structure determinations on various transition metal ion complexes of three terpyridine ligands carrying trimethoxyphenyl substituents has enabled an assessment of the contribution made by the ligand components to the interactions determining the lattice structures, interactions expected also to be present in metallomesogens derived from similar ligands. The form of the link joining the trimethoxyphenyl substituent to the 4? position of 2,2?;6?,2?-terpyridine is of some importance. In the case of the Co(II) complexes of two of the ligands, their spin-crossover characteristics can be rationalised in terms of the different interactions seen in their lattices. PMID:24132156

Lee, Young Hoon; Harrowfield, Jack M.; Shin, Jong Won; Won, Mi Seon; Rukmini, Elisabeth; Hayami, Shinya; Min, Kil Sik; Kim, Yang

2013-01-01

34

Sounding-derived parameters associated with large hail and tornadoes in the Netherlands  

Microsoft Academic Search

A study is presented focusing on the potential value of parameters derived from radiosonde data or data from numerical atmospheric models for the forecasting of severe weather associated with convective storms. Parameters have been derived from soundings in the proximity of large hail, tornadoes (including tornadoes over water: waterspouts) and thunderstorms in the Netherlands. 66,365 radiosonde soundings from six stations

P. H. Groenemeijer; A. van Delden

2007-01-01

35

Interactions of Arsenic and the Dissolved Substances Derived from  

E-print Network

Interactions of Arsenic and the Dissolved Substances Derived from Turf Soils Z H A N G R O N G C H with substances of molecular weight (MW) between 500 and 3500 Da; (3) the association of As and dissolved organic

Florida, University of

36

Derivative-expansion approach to the interaction between close surfaces  

NASA Astrophysics Data System (ADS)

The derivative-expansion approach to the calculation of the interaction between two surfaces is a generalization of the proximity force approximation, a technique in widespread use in different areas of physics. The derivative expansion has so far been applied to seemingly unrelated problems in different areas; it is our principal aim here to present the approach in its full generality. To that end, we introduce a unified setting, which is independent of any particular application, provide a formal derivation of the derivative expansion in that general setting, and study some of its properties. With a view toward the possible application of the derivative expansion to other areas, like nuclear and colloidal physics, we also discuss the relation between the derivative expansion and some time-honored uncontrolled approximations used in these contexts. By putting them under similar terms as in the derivative expansion, we believe that the path is open to the calculation of next-to-leading-order corrections also for these contexts. We also review some results obtained within the derivative expansion, by applying it to different concrete examples and highlighting some important points.

Fosco, C. D.; Lombardo, F. C.; Mazzitelli, F. D.

2014-06-01

37

Characterizing Tissue with Acoustic Parameters Derived from Ultrasound Data  

SciTech Connect

In contrast to standard reflection ultrasound (US), transmission US holds the promise of more thorough tissue characterization by generating quantitative acoustic parameters. We compare results from a conventional US scanner with data acquired using an experimental circular scanner operating at frequencies of 0.3 - 1.5 MHz. Data were obtained on phantoms and a normal, formalin-fixed, excised breast. Both reflection and transmission-based algorithms were used to generate images of reflectivity, sound speed and attenuation.. Images of the phantoms demonstrate the ability to detect sub-mm features and quantify acoustic properties such as sound speed and attenuation. The human breast specimen showed full field evaluation, improved penetration and tissue definition. Comparison with conventional US indicates the potential for better margin definition and acoustic characterization of masses, particularly in the complex scattering environments of human breast tissue. The use of morphology, in the context of reflectivity, sound speed and attenuation, for characterizing tissue, is discussed.

Littrup, P; Duric, N; Leach, R R; Azevedo, S G; Candy, J V; Moore, T; Chambers, D H; Mast, J E; Johnson, S A; Holsapple, E

2002-01-23

38

Source parameters derived from seismic spectrum in the Jalisco block  

NASA Astrophysics Data System (ADS)

The direct measure of the earthquake fault dimension represent a complicated task nevertheless a better approach is using the seismic waves spectrum. With this method we can estimate the dimensions of the fault, the stress drop and the seismic moment. The study area comprises the complex tectonic configuration of Jalisco block and the subduction of the Rivera plate beneath the North American plate; this causes that occur in Jalisco some of the most harmful earthquakes and other related natural disasters. Accordingly it is important to monitor and perform studies that helps to understand the physics of earthquake rupture mechanism in the area. The main proposue of this study is estimate earthquake seismic source parameters. The data was recorded by the MARS network (Mapping the Riviera Subduction Zone) and the RESAJ network. MARS had 51 stations and settled in the Jalisco block; that is delimited by the mesoamerican trench at the west, the Colima grabben to the south, and the Tepic-Zacoalco to the north; for a period of time, of January 1, 2006 until December 31, 2007 Of this network was taken 104 events, the magnitude range of these was between 3 to 6.5 MB. RESJAL has 10 stations and is within the state of Jalisco, began to record since October 2011 and continues to record. We firs remove the trend, the mean and the instrument response, then manually chosen the S wave, then the multitaper method was used to obtain the spectrum of this wave and so estimate the corner frequency and the spectra level. We substitude the obtained in the equations of the Brune model to calculate the source parameters. Doing this we obtained the following results; the source radius was between .1 to 2 km, the stress drop was between .1 to 2 MPa.

Gutierrez, Q. J.; Escudero, C. R.; Nunez-Cornu, F. J.

2012-12-01

39

Effect of hematoporphyrin derivative on hematological parameters in rats.  

PubMed

Wistar rats were injected with hematoporphyrin derivative (Hpd) intraperitoneally and kept in the dark. Rats were sacrificed 2,24,48 and 72 h after injection. It was observed that Hpd in the dark did not affect the hemoglobin content and number of erythrocytes, while the leukocyte count was increased and blood pH decreased. Blood levels of glucose and lactate were increased significantly. Because the food intake was similar in all the groups, glycogenolysis was suspected to be the source of increased glucose levels in blood. However, a significant increase in the glycogen content of the livers of Hpd-treated rats was observed, which rules out glycogenolysis. Hyperglycemia may result due to a number of reasons such as stimulation of the central nervous pathways innervating the liver and adrenal medulla, excessive glucogenesis in liver from glycogen and noncarbohydrate sources, emotional stress, anesthesia and hormonal effects. The present study rules out hyperglycemia due to anesthesia and glucogenesis in the liver. Maintenance of blood glucose levels is a highly complex mechanism. Further investigations to understand these mechanisms are in progress. PMID:7480138

Khanum, F; Anilakumar, K R; Santhanam, K

1995-08-01

40

Recursion method for deriving an energy-independent effective interaction  

NASA Astrophysics Data System (ADS)

The effective-interaction theory has been one of the useful and practical methods for solving nuclear many-body problems based on the shell model. Various approaches have been proposed which are constructed in terms of the so-called Q? box and its energy derivatives introduced by Kuo et al. In order to find out a method of calculating them we make a decomposition of a full Hilbert space into subspaces (the Krylov subspaces) and transform a Hamiltonian to a block-tridiagonal form. This transformation brings about much simplification of the calculation of the Q? box. In the previous work a recursion method was derived for calculating the Q? box analytically on the basis of such transformation of the Hamiltonian. In the present study, by extending the recursion method for the Q? box, we derive another recursion relation to calculate the derivatives of the Q? box of arbitrary order. With the Q? box and its derivatives thus determined we apply them to the calculation of the E-independent effective interaction given in the so-called Lee-Suzuki (LS) method for a system with a degenerate unperturbed energy. We show that the recursion method can also be applied to the generalized LS scheme for a system with nondegenerate unperturbed energies. If the Hilbert space is taken to be sufficiently large, the theory provides an exact way of calculating the Q? box and its derivatives. This approach enables us to perform recursive calculations for the effective interaction to arbitrary order for both systems with degenerate and nondegenerate unperturbed energies.

Suzuki, Kenji; Kumagai, Hiroo; Okamoto, Ryoji; Matsuzaki, Masayuki

2014-04-01

41

Recursion Method for Deriving Energy-Independent Effective Interaction  

E-print Network

The effective-interaction theory has been one of the useful and practical methods for solving nuclear many-body problems based on the shell model. Various approaches have been proposed which are constructed in terms of the so-called $\\widehat{Q}$ box and its energy derivatives introduced by Kuo {\\it et al}. In order to find out a method of calculating them we make decomposition of a full Hilbert space into subspaces (the Krylov subspaces) and transform a Hamiltonian to a block-tridiagonal form. This transformation brings about much simplification of the calculation of the $\\widehat{Q}$ box. In the previous work a recursion method has been derived for calculating the $\\widehat{Q}$ box analytically on the basis of such transformation of the Hamiltonian. In the present study, by extending the recursion method for the $\\widehat{Q}$ box, we derive another recursion relation to calculate the derivatives of the $\\widehat{Q}$ box of arbitrary order. With the $\\widehat{Q}$ box and its derivatives thus determined we apply them to the calculation of the $E$-independent effective interaction given in the so-called Lee-Suzuki (LS) method for a system with a degenerate unperturbed energy. We show that the recursion method can also be applied to the generalized LS scheme for a system with non-degenerate unperturbed energies. If the Hilbert space is taken to be sufficiently large, the theory provides an exact way of calculating the $\\widehat{Q}$ box and its derivatives. This approach enables us to perform recursive calculations for the effective interaction to arbitrary order for both systems with degenerate and non-degenerate unperturbed energies.

Kenji Suzuki; Hiroo Kumagai; Ryoji Okamoto; Masayuki Matsuzaki

2014-02-12

42

Technique for Calculating Solution Derivatives With Respect to Geometry Parameters in a CFD Code  

NASA Technical Reports Server (NTRS)

A solution has been developed to the challenges of computation of derivatives with respect to geometry, which is not straightforward because these are not typically direct inputs to the computational fluid dynamics (CFD) solver. To overcome these issues, a procedure has been devised that can be used without having access to the mesh generator, while still being applicable to all types of meshes. The basic approach is inspired by the mesh motion algorithms used to deform the interior mesh nodes in a smooth manner when the surface nodes, for example, are in a fluid structure interaction problem. The general idea is to model the mesh edges and nodes as constituting a spring-mass system. Changes to boundary node locations are propagated to interior nodes by allowing them to assume their new equilibrium positions, for instance, one where the forces on each node are in balance. The main advantage of the technique is that it is independent of the volumetric mesh generator, and can be applied to structured, unstructured, single- and multi-block meshes. It essentially reduces the problem down to defining the surface mesh node derivatives with respect to the geometry parameters of interest. For analytical geometries, this is quite straightforward. In the more general case, one would need to be able to interrogate the underlying parametric CAD (computer aided design) model and to evaluate the derivatives either analytically, or by a finite difference technique. Because the technique is based on a partial differential equation (PDE), it is applicable not only to forward mode problems (where derivatives of all the output quantities are computed with respect to a single input), but it could also be extended to the adjoint problem, either by using an analytical adjoint of the PDE or a discrete analog.

Mathur, Sanjay

2011-01-01

43

Power Saving Optimization for Linear Collider Interaction Region Parameters  

SciTech Connect

Optimization of Interaction Region parameters of a TeV energy scale linear collider has to take into account constraints defined by phenomena such as beam-beam focusing forces, beamstrahlung radiation, and hour-glass effect. With those constraints, achieving a desired luminosity of about 2E34 would require use of e{sup +}e{sup -} beams with about 10 MW average power. Application of the 'travelling focus' regime may allow the required beam power to be reduced by at least a factor of two, helping reduce the cost of the collider, while keeping the beamstrahlung energy loss reasonably low. The technique is illustrated for the 500 GeV CM parameters of the International Linear Collider. This technique may also in principle allow recycling the e{sup +}e{sup -} beams and/or recuperation of their energy.

Seryi, Andrei; /SLAC

2009-10-30

44

Recursion Method for Deriving Energy-Independent Effective Interaction  

E-print Network

The effective-interaction theory has been one of the useful and practical methods for solving nuclear many-body problems based on the shell model. Various approaches have been proposed which are constructed in terms of the so-called $\\widehat{Q}$ box and its energy derivatives introduced by Kuo {\\it et al}. In order to find out a method of calculating them we make decomposition of a full Hilbert space into subspaces (the Krylov subspaces) and transform a Hamiltonian to a block-tridiagonal form. This transformation brings about much simplification of the calculation of the $\\widehat{Q}$ box. In the previous work a recursion method has been derived for calculating the $\\widehat{Q}$ box analytically on the basis of such transformation of the Hamiltonian. In the present study, by extending the recursion method for the $\\widehat{Q}$ box, we derive another recursion relation to calculate the derivatives of the $\\widehat{Q}$ box of arbitrary order. With the $\\widehat{Q}$ box and its derivatives thus determined we ap...

Suzuki, Kenji; Okamoto, Ryoji; Matsuzaki, Masayuki

2014-01-01

45

Derivation of circuit-breaker parameters by means of Gaussian approximation  

SciTech Connect

Dynamic arc models describe the circuit-breaker in its individuality by empirical parameters that have to be derived from current zero oscillograms. In case of the Urbanek model the differential equation for the arc conductance can be generally integrated because only four constant parameters are used. For that case the empirical constants can be derived by Gaussian approximation of the empirically obtained arc conductance (from a current zero oscillogram) by the arc model.

Blahous, L.

1982-12-01

46

ANALYSIS OF FOUR-PARAMETER FRACTIONAL DERIVATIVE MODEL OF REAL SOLID MATERIALS  

Microsoft Academic Search

The introduction of fractional derivatives into the constitutive equation of the differential operator type of linear solid materials has led to the development of the so-called fractional derivative models. One of these models, characterized by four parameters, has been found usable for describing the variation of dynamics elastic and damping properties in a wide frequency range, provided that there is

T. Pritz

1996-01-01

47

Parameter interaction in the perception of French plosives.  

PubMed

This investigation takes as its point of departure observations on the production of French fortis versus lenis plosive consonants. In a series of perception tests the role of different parameters in the fortis versus lenis distinction found in production (e.g. duration of the pre-consonantal vowel, the consonantal closure, voicing during the closure and intensity of the consonantal release noise) was investigated. Apart from durational and intensity parameters, vowel quality differences (depending on the fortis versus lenis character of the following consonant) are also shown to play a part in phoneme identification. Furthermore it is shown that in obstruent clusters like /tp, dp/ versus /tg, dg/ not only do phonetic parameters like those mentioned above influence perception, but that also the phonemic identity of /p/ versus /g/ as fortis versus lenis contributes to the hearers' decision about the identity of the first consonant in the cluster. Phonetic as well as contextual factors are shown to interact in a complex manner. Implications of the results for speech perception theory are discussed. PMID:6844417

van Dommelen, W A

1983-01-01

48

Estimates of genetic parameters in Arabic coffee derived from the Timor hybrid  

Microsoft Academic Search

Genetic parameters of Arabic coffee progenies derived from the cross 'Villa Sarchi' x 'Timor hybrid' were estimated in order to evaluate their potential for improvement. The experiment was installed in a random block design with ten treatments, eight replicates and eight plants per plot. The parameters cherry yield, plant height, canopy diameter, seed types and sizes were estimated. Results demonstrated

Júlio César Mistro; Luiz Carlos Fazuoli; Paulo Boller Gallo; Antonio Carlos; Baião de Oliveira; Masako Toma-Braghini; Maria Bernadete Silvarolla

49

Resonance Parameters and Uncertainties Derived from Epithermal Neutron Capture and Transmission Measurements of Natural Molybdenum  

E-print Network

Resonance Parameters and Uncertainties Derived from Epithermal Neutron Capture and Transmission capture and transmission measurements were performed by the time-of-flight technique. Resonance parameters were extracted from the data using the multilevel R-matrix Bayesian code SAMMY. A table of resonance

Danon, Yaron

50

Binding interactions of water-soluble camptothecin derivatives with bovine serum albumin  

NASA Astrophysics Data System (ADS)

In this study, the binding interactions of the water-soluble camptothecin derivatives hydroxycamptothecin (10-HCPT), topotecan (TPT), and camptothecin quaternary salt (CPT8), to bovine serum albumin (BSA) were determined using fluorescence spectra and UV-vis spectra. The results revealed that the fluorescence of BSA was strongly quenched by the binding of camptothecin derivatives to BSA. The quenching mechanism of the camptothecin derivatives was found to be static according to the Stern-Volmer equation. The binding constant and binding sites were confirmed by fluorescence quenching spectra. The thermodynamic parameters Gibbs free energy change (? G < 0), enthalpy change (? H > 0), and entropy change (? S > 0) implied that the interaction process was spontaneous and endothermic, and the interaction forces between camptothecin compounds and BSA were found to be hydrophobic. According to Föster non-radioactive energy transfer, the binding distances between 10-HCPT, TPT, and CPT8, and BSA were determined to be 1.73 nm, 1.63 nm, and 1.61 nm, respectively. The synchronous fluorescence spectra confirmed that the camptothecin compounds cannot cause conformational changes in BSA. A rapid and sensitive method for determining the binding interaction between water-soluble camptothecin derivatives and BSA was established based on these principles of fluorescence quenching.

Li, Qingyong; Zhu, Qiaochu; Deng, Xiaoqiu; He, Wuna; Zhao, Tengfei; Zhang, Baoyou

2012-02-01

51

Deriving physical parameters of unresolved star clusters. II. The degeneracies of age, mass, extinction, and metallicity  

E-print Network

This paper is the second of a series that investigates the stochasticity and degeneracy problems that hinder the derivation of the age, mass, extinction, and metallicity of unresolved star clusters in external galaxies when broad-band photometry is used. While Paper I concentrated on deriving age, mass, and extinction of star clusters for one fixed metallicity, we here derive these parameters in case when metallicity is let free to vary. The results were obtained using several different filter systems ($UBVRI$, $UBVRIJHK$, GALEX+$UBVRI$), which allowed to optimally reduce the different degeneracies between the cluster physical parameters. The age, mass, and extinction of a sample of artificial star clusters were derived by comparing their broad-band integrated magnitudes with the magnitudes of a large grid of cluster models with various metallicities. A large collection of artificial clusters was studied to model the different degeneracies in the age, mass, extinction, and metallicity parameter space when sto...

de Meulenaer, Philippe; Mineikis, Tadas; Vansevi?ius, Vladas

2014-01-01

52

Ultlra-intense laser-matter interactions at extreme parameters  

SciTech Connect

The field of shortpulse lasers has seen rapid growth in the recent years with the three major boundaries of energy, pulse duration and repetition rate being pushed in ever extremer regions. At peak powers, already exceeding 10{sup 22} W/cm{sup 2}, in virtually every experiment in relativistic laser physics, the laser pulse interacts with a more or less extended and heated plasma, due to prepulses and ASE-like pedestals on ps - ns time scales. By developing a new technique for ultrahigh contrast, we were able to initiate the next paradigm shift in relativistic laser-matter interactions, allowing us to interact ultrarelativistic pulses volumetrically with overdense targets. This becomes possible by using target and laser parameters that will turn the target relativistically transparent during the few 10s-100s femtoseconds fo the interaction. Specifically, we interact an ultraintese, ultrahigh contrast pulse with solid density, free standing, nanometer diamond target. This paradigm change towards a volumetric overdense interaction in turn enables new particle acceleration mechanisms for both electrons and ions, as well as forward directed relativistic surface harmonics. We report here on first experiments done on those topics at the 200 TW Trident laser at Los Alamos as well as at the Ti:Sapphire system at MBI. We will compare the experimental data to massive large scale 3D simulations done on the prototype of LANL's new Petafiop supercomputer Roadrunner, which is leading the current top 500 list. Specifically, we developed a shortpulse OPA based pulse cleaning technique. Fielding it at the Trident 200 TW laser at Los Alamos, we were able to improve the pulse contrast by 6 orders of magnitude to better than 2 x 10{sup -12} at less than a ps. This enabled for the first time the interaction of a 100J, 200TW laser pulse with a truly solid target with virtually no expansion before the main pulse - target interaction, making possible the use of very thin targets, The thinnest of these at less than 3nm, i.e. 1/300 of the laser wavelength, are even thinner than the plasma skin depth. This drastically changes the laser-matter interaction physics leading to the emergence of new particle acceleration mechanisms, like Break-Out Afterburner (BOA) Acceleration, driven by a relativistic, kinetic plasma instability or Radiation Pressure Acceleration (RPA), driven by stabilized charge separation. Furthermore, these interactions also produce relativistic high harmonics in forward direction as well as mono-en,ergetic electron pulses which might lend itself as a source for fully coherent Thomson scattering in the mulit-keV regime. In this talk I will present an overview over the laser developments leading to this paradigm change as well as over the theoretical and experimental results following from it. Specifically we were able for the first time to demonstrate BOA acceleration of Carbon ions to up to 0.5 GeV using a laser pulse with {approx}10{sup 20} W/cm{sup 2} intensity and showing the scalability of this mechanism into regimes relevant for Hadron Therapy. We were further able to demonstrate mono-energetic electron break-out from ultrathin targets, as a first step towards a flying mirror.

Hegellich, Bjorn M [Los Alamos National Laboratory

2010-11-24

53

Kadyshevsky Field Theory ---Derivative-Interactions and Functional Integral Formalism---  

NASA Astrophysics Data System (ADS)

Field theoretical topics are discussed and introduced in the framework of the Quantum Field Theory as developed by Kadyshevsky. In the first part we cover the topics: Relation between the Feynman and Kadyshevsky perturbation theory, and the Gross-Jackiw method for derivative-interactions in the Kadyshevsky formalism. In the second part we first construct the second-quantized quasi-particle formalism, which is employed to formulate the functional integral formalism. In the latter we develop the path-integral, the Schwinger-Symanzik equations, generalized Wightman functions, and the Kadyshevky reduction formulas.

Rijken, T.; Wagenaar, J.

54

On Consistent Kinetic and Derivative Interactions for Gravitons  

E-print Network

The only known fully ghost-free and consistent Lorentz-invariant kinetic term for a graviton (or indeed for any spin-2 field) is the Einstein-Hilbert term. Here we propose and investigate a new family of candidate kinetic interactions and their extensions to derivative interactions involving several spin-2 fields. These new terms generically break diffeomorphism invariance(s) and as a result can lead to the propagation of 5 degrees of freedom for a single spin-2 field - analogous to ghost-free Massive Gravity. We discuss under what circumstances these new terms can be used to build healthy effective field theories and in the process establish the `Jordan' and `Einstein' frame pictures for Massive-, Bi- and Multi-Gravity.

Noller, Johannes

2014-01-01

55

Solvatochromism of anthraquinone and symmetrical dihydroxy derivatives. Local interactions  

NASA Astrophysics Data System (ADS)

The solvent effects on the electronic absorption spectra of 9,10-anthraquinone (AQ) and its symmetric dihydroxy derivatives namely 1,5-dihydroxyanthraquinone (1,5-DHAQ) and 2,6-dihydroxyanthraquinone (2,6-DHAQ) have been studied in pure solvents and some binary solvent mixtures. The frequencies of the absorption for AQ and 2,6-DHAQ are quite solvent sensitive while those for 1,5-DHAQ are not. Due to the intramolecular hydrogen bond between the C?O and OH groups, no influence of solvent hydrogen bond acceptors is observed in 1,5-DHAQ. This hydrogen bond gives a stable six member cycle which is not broken even by the strongest hydrogen bond acceptor solvents used in this work, such as DMSO and DMF. The Taft and Kamlet's solvatochromic comparison method was applied for AQ and 2,6-DHAQ. Aromatic solvents and aliphatic amines were not included in the correlations since they strongly deviate suggesting another type of interactions. All the ??? * bands of AQ and 2,6-DHAQ show strong influence of ? * despite the fact that their dipole moment is zero. Although it would be reasonable to expect that in the absence of a solute dipole moment there is not significant orientation of solvent molecules around the solute molecules, in this case dipolar interactions between solute and solvent due to local effects might be expected. AQ may be considered as formed by two carbonyl groups weakly interacting with the benzene rings; that means that the carbonyl group can behave as an isolated dipole and independently of the other. To detect possible specific interactions between the AQ and aliphatic amines and aromatic hydrocarbons, preferential solvation in mixed solvent was investigated. It is concluded that EDA interactions are important in the solvation of AQ with these compounds as solvents.

Reta, Mario R.; Cartana, Rosa; Anunziata, Jorge D.; Silber, Juana J.

1993-07-01

56

Derivatives of buckling loads and vibration frequencies with respect to stiffness and initial strain parameters  

NASA Technical Reports Server (NTRS)

A uniform variational approach to sensitivity analysis of vibration frequencies and bifurcation loads of nonlinear structures is developed. Two methods of calculating the sensitivities of bifurcation buckling loads and vibration frequencies of nonlinear structures, with respect to stiffness and initial strain parameters, are presented. A direct method requires calculation of derivatives of the prebuckling state with respect to these parameters. An adjoint method bypasses the need for these derivatives by using instead the strain field associated with the second-order postbuckling state. An operator notation is used and the derivation is based on the principle of virtual work. The derivative computations are easily implemented in structural analysis programs. This is demonstrated by examples using a general purpose, finite element program and a shell-of-revolution program.

Haftka, Raphael T.; Cohen, Gerald A.; Mroz, Zenon

1990-01-01

57

Stochasticity effects on derivation of physical parameters of unresolved star clusters  

E-print Network

We developed a method for a fast modeling of broad-band UBVRI integrated magnitudes of unresolved star clusters and used it to derive their physical parameters (age, mass, and extinction). The method was applied on M33 galaxy cluster sample and consistency of ages and masses derived from unresolved observations with the values derived from resolved stellar photometry was demonstrated. We found that interstellar extinction causes minor age-extinction degeneracy for the studied sample due to a narrow extinction range in M33.

de Meulenaer, Philippe; Mineikis, Tadas; Vansevi?ius, Vladas

2013-01-01

58

Solubility and interaction parameters as references for solution properties II: precipitation and aggregation of asphaltene in organic solvents.  

PubMed

The total combinatory Gibbs free energy was successfully used to model the solubility of two purified asphaltenes in pure and mixed solvents, as well as the precipitation of asphaltenes from mixed solvents. Intrinsic viscosity and aggregate size both sensitively reflected the state of the asphaltenes in homogeneous solution and were used for determining the solubility parameters of the asphaltenes. Phase separation was clearly reflected by a dramatic increase in aggregate size. The interaction parameter was subdivided into enthalpy and entropy contributions. All parameters indicate an extensive association or phase transition when the phase boundary was followed by simultaneously varying the temperature and the solubility parameter of the solvent. However, the interaction parameter is frequently derived in two ways. We show that, depending on the definition, the enthalpy and entropy contributions lead to conflicting results. These were evaluated on thermodynamic grounds. PMID:19019320

Johansson, Bjarne; Friman, Rauno; Hakanpää-Laitinen, Hannele; Rosenholm, Jarl B

2009-01-01

59

Baseline 18F-FDG PET image derived parameters for therapy response prediction in oesophageal cancer  

E-print Network

1 Baseline 18F-FDG PET image derived parameters for therapy response prediction in oesophageal for therapy response Keywords: oesophageal cancer, response to therapy, PET scan, tumour volume, total lesion of tumour measurements on 18F-FDG PET pretreatment scan regarding therapy response in oesophageal cancer

Paris-Sud XI, Université de

60

Derivation and use of trust and risk management parameters in dynamic federated environments  

E-print Network

use of both, formula- based trust quantification and risk assessment, in dynamic access controlDerivation and use of trust and risk management parameters in dynamic federated environments Latifa-based access control mechanisms. 1 Motivation for managing risk and trust in dynamic federated environments

61

Validating a large geophysical data set - Experiences with satellite-derived cloud parameters  

NASA Technical Reports Server (NTRS)

The goal of this study is to validate the global cloud parameters derived from the satellite-borne HIRS2 and MSU atmospheric sounding instrument measurements, and to use the analysis of these data as one prototype for studying large geophysical data sets in general. The HIRS2/MSU data set contains a total of 40 physical parameters, filling 25 MB/day; raw HIRS2/MSU data are available for a period exceeding 10 years. Validation involves developing a quantitative sense for the physical meaning of the derived parameters over the range of environmental conditions sampled. This is accomplished by comparing the spatial and temporal distributions of the derived quantities with similar measurements made using other techniques, and with model results. The need to work with Level 2 (point) data, rather than Level 3 (gridded) data for validation purposes is discussed, and some techniques developed for charting the assumptions made in deriving an algorithm and generating a code to produce geophysical quantities from measured radiances are presented.

Kahn, Ralph; Haskins, Robert D.; Knighton, James E.; Pursch, Andrew; Granger-Gallegos, Stephanie

1991-01-01

62

Satellite-derived land surface parameters for mesoscale modelling of the Mexico City basin  

Microsoft Academic Search

Mesoscale meteorological modelling is an important tool to help understand air pol- lution and heat island e ects in urban areas. Accurate wind simulations are di cult to obtain in areas of weak synoptic forcing. Local factors have a dominant role in the circulation and include land surface parameters and their interaction with the atmo- 5 sphere. This paper examines

B. de Fo; L. T. Molina; M. J. Molina

2005-01-01

63

Deriving reliable fundamental parameters of pre-main-sequence-rich star clusters affected by differential reddening  

NASA Astrophysics Data System (ADS)

We present an approach that improves the search for reliable astrophysical parameters (e.g. age, mass and distance) of differentially reddened, pre-main-sequence-rich star clusters. It involves simulating conditions related to the early-cluster phases, in particular the differential and foreground reddenings, and internal age spread. Given the loose constraints imposed by these factors, the derivation of parameters based only on photometry may be uncertain, especially for the poorly populated clusters. We consider a wide range of cluster (i) mass and (ii) age, and different values of (iii) distance modulus, (iv) differential and (v) foreground reddenings. Photometric errors and their relation with magnitude are also taken into account. We also investigate how the presence of unresolved binaries affect the derived parameters. For each set of (i)-(v) we build the corresponding model Hess diagram, and compute the root mean squared residual with respect to the observed Hess diagram. The parameters that produce the minimum residuals between model and observed Hess diagrams are searched by exploring the full parameter space of (i)-(v) by means of brute force, which may be time consuming but efficient. Control tests show that an adequate convergence is achieved allowing for solutions with residuals 10 per cent higher than the absolute minimum. Compared to a colour-magnitude diagram containing only single stars, the presence of 100 per cent of unresolved binaries has little effect on cluster age, foreground and differential reddenings; significant differences show up in the cluster mass and distance from the Sun. Our approach proves to be successful in minimizing the subjectiveness when deriving fundamental parameters of young star clusters.

Bonatto, C.; Bica, E.; Lima, E. F.

2012-02-01

64

Cubic interaction parameters for t2g Wannier orbitals  

NASA Astrophysics Data System (ADS)

Many-body calculations for multi-orbital systems at present typically employ Slater or Kanamori interactions which implicitly assume a full rotational invariance of the orbitals, whereas the real crystal has a lower symmetry. In cubic symmetry, the low-energy t2g orbitals have an on-site Kanamori interaction, albeit without the constraint U =U'+2J implied by spherical symmetry (U is the intra-orbital interaction, U' is the interorbital interaction, J is Hund's exchange). Using maximally localized Wannier functions we show that deviations from the standard, spherically symmetric interactions are indeed significant for 5d orbitals (˜25% for BaOsO3; ˜12% if screening is included) but are less important for 3d orbitals (˜6% for SrVO3; ˜1% if screened).

Ribic, T.; Assmann, E.; Tóth, A.; Held, K.

2014-10-01

65

Identification of fractional-derivative-model parameters of viscoelastic materials from measured FRFs  

Microsoft Academic Search

The dynamic properties of viscoelastic damping materials are highly frequency- and temperature-dependent. Numerical methods of structural and acoustic systems require the mathematical model for these dependencies. The fractional-derivative model on damping material has become a powerful solution that describes the frequency-dependent dynamic characteristics of damping materials. The model parameters on a damping material are very important information both for describing

Sun-Yong Kim; Doo-Ho Lee

2009-01-01

66

Derivation of hydrous pyrolysis kinetic parameters from open-system pyrolysis  

Microsoft Academic Search

Kinetic information is essential to predict the temperature, timing or depth of hydrocarbon generation within a hydrocarbon system. The most common experiments for deriving kinetic parameters are mainly by open-system pyrolysis. However, it has been shown that the conditions of open-system pyrolysis are deviant from nature by its low near-ambient pressure and high temperatures. Also, the extrapolation of heating rates

Yu-Hsin Tseng; Wuu-Liang Huang

2010-01-01

67

Deriving physical parameters of unresolved star clusters. I. Age, mass, and extinction degeneracies  

E-print Network

Context. Stochasticity and physical parameter degeneracy problems complicate the derivation of the parameters (age, mass, and extinction) of unresolved star clusters when using broad-band photometry. Aims. We develop a method to simulate stochasticity and degeneracies, and to investigate their influence on the accuracy of derived physical parameters. Then we apply it to star cluster samples of M31 and M33 galaxies. Methods. Age, mass and extinction of observed star clusters are derived by comparing their broad-band UBVRI integrated magnitudes to the magnitudes of a large grid of star cluster models with fixed metallicity Z=0.008. Masses of stars for a cluster model are randomly sampled from the initial mass function. Models of star clusters from the model grid, which have all of their magnitudes located within 3 observational errors from the magnitudes of the observed cluster, are selected for the computation of its age, mass, and extinction. Results. In the case of the M31 galaxy, the extinction range is wid...

de Meulenaer, Philippe; Mineikis, Tadas; Vansevi?ius, Vladas

2013-01-01

68

An investigation of using an RQP based method to calculate parameter sensitivity derivatives  

NASA Technical Reports Server (NTRS)

Estimation of the sensitivity of problem functions with respect to problem variables forms the basis for many of our modern day algorithms for engineering optimization. The most common application of problem sensitivities has been in the calculation of objective function and constraint partial derivatives for determining search directions and optimality conditions. A second form of sensitivity analysis, parameter sensitivity, has also become an important topic in recent years. By parameter sensitivity, researchers refer to the estimation of changes in the modeling functions and current design point due to small changes in the fixed parameters of the formulation. Methods for calculating these derivatives have been proposed by several authors (Armacost and Fiacco 1974, Sobieski et al 1981, Schmit and Chang 1984, and Vanderplaats and Yoshida 1985). Two drawbacks to estimating parameter sensitivities by current methods have been: (1) the need for second order information about the Lagrangian at the current point, and (2) the estimates assume no change in the active set of constraints. The first of these two problems is addressed here and a new algorithm is proposed that does not require explicit calculation of second order information.

Beltracchi, Todd J.; Gabriele, Gary A.

1989-01-01

69

Cloud parameters derived from GOES during the 1987 marine stratocumulus FIRE Intensive Field Observation (IFO) period  

NASA Technical Reports Server (NTRS)

The Geostationary Operational Environmental Satellite (GOES) is well suited for observations of the variations of clouds over many temporal and spatial scales. For this reason, GOES data taken during the Marine Stratocumulus Intensive Field Observations (IFO) (June 29 to July 19, 1987, Kloessel et al.) serve several purposes. One facet of the First ISCCP Regional Experiment (FIRE) is improvement of the understanding of cloud parameter retrievals from satellite-observed radiances. This involves comparisons of coincident satellite cloud parameters and high resolution data taken by various instruments on other platforms during the IFO periods. Another aspect of FIRE is the improvement of both large- and small-scale models of stratocumulus used in general circulation models (GCMs). This may involve, among other studies, linking the small-scale processes observed during the IFO to the variations in large-scale cloud fields observed with the satellites during the IFO and Extended Time Observation (ETO) periods. Preliminary results are presented of an analysis of GOES data covering most of the IFO period. The large scale cloud-field characteristics are derived, then related to a longer period of measurements. Finally, some point measurements taken from the surface are compared to regional scale cloud parameters derived from satellite radiances.

Young, David F.; Minnis, Patrick; Harrison, Edwin F.

1990-01-01

70

The physical and biological basis of quantitative parameters derived from diffusion MRI.  

PubMed

Diffusion magnetic resonance imaging is a quantitative imaging technique that measures the underlying molecular diffusion of protons. Diffusion-weighted imaging (DWI) quantifies the apparent diffusion coefficient (ADC) which was first used to detect early ischemic stroke. However this does not take account of the directional dependence of diffusion seen in biological systems (anisotropy).Diffusion tensor imaging (DTI) provides a mathematical model of diffusion anisotropy and is widely used. Parameters, including fractional anisotropy (FA), mean diffusivity (MD), parallel and perpendicular diffusivity can be derived to provide sensitive, but non-specific, measures of altered tissue structure. They are typically assessed in clinical studies by voxel-based or region-of-interest based analyses.The increasing recognition of the limitations of the diffusion tensor model has led to more complex multi-compartment models such as CHARMED, AxCaliber or NODDI being developed to estimate microstructural parameters including axonal diameter, axonal density and fiber orientations. However these are not yet in routine clinical use due to lengthy acquisition times.In this review, I discuss how molecular diffusion may be measured using diffusion MRI, the biological and physical bases for the parameters derived from DWI and DTI, how these are used in clinical studies and the prospect of more complex tissue models providing helpful micro-structural information. PMID:23289085

Winston, Gavin P

2012-12-01

71

Usefulness of Derived Frank Lead Parameters in Screening for Coronary Artery Disease and Cardiomyopathy  

NASA Technical Reports Server (NTRS)

We investigated the accuracy of several known as well as newly-introduced derived Frank-lead ECG parameters in differentiating healthy individuals from patients with obstructive coronary artery disease (CAD) and cardiomyopathy (CM). Advanced high-fidelity 12-lead ECG tests (approx. 5-min supine) were first performed on a "training set" of 99 individuals: 33 with ischemic or dilated CM and low ejection fraction (EF less than 40%); 33 with catheterization-proven obstructive CAD but normal EF; and 33 age-/gender-matched healthy controls. The following derived Frank lead parameters were studied for their accuracy in detecting CAD and CM: the spatial ventricular gradient (VG), including its beat-to-beat coefficient of variability (VG CV); the spatial mean QRS (SM-QRS) and T-waves (SM-T) and their beat-to-beat coefficients of variability; the spatial ventricular activation time (VAT); the mean and maximum spatial QRS-T angles; and standard late potentials parameters (RMS40, fQRSD and LAS). Several of these parameters were accurate in discriminating between the control group and both diseased groups at p less than 0.0001. For example the fQRSD, VG CV, mean spatial QRS-T angle and VG minus SM-QRS (which is similar to the SM-T) had retrospective areas under the ROC curve of 0.78, 0.78, 0.80, and 0.84 (CAD vs. controls) and 0.93, 0.88, 0.98 and 0.99 (CM vs. controls), respectively. The single most effective parameter in discriminating between the CAD and CM groups was the spatial VAT (44 plus or minus 5.8 vs. 53 plus or minus 9.9 ms, p less than 0.0001), with an area under the ROC curve of 0.80. Since subsequent prospective analyses using new groups of patients and healthy subjects have yielded only slightly less accurate results, we conclude that derived Frank-lead parameters show great promise for potentially contributing to the development of a rapid and inexpensive resting ECG-based screening test for heart disease.

DePalma, J. L.; Schlegel, T. T.; Arenare, B.; Greco, E. C.; Starc, V.; Rahman, M. A.; Delgado, R.

2007-01-01

72

Remote sensing of atmosphere-surface interaction parameters  

NASA Technical Reports Server (NTRS)

Examples are given of the accuracy of the results obtained from the HIRS 2/MSU (High Resolution Infrared Sounder and Microwave Sounding Unit) analysis of ocean, atmosphere, and land parameters. Sea surface temperatures are compared with available ship and buoy radiosonde data, and land surface temperatures are compared with shelter temperatures. The seasonal change in land and ocean skin surface temperature is reviewed. The distribution of clouds is examined and their opacities in the visible and infrared parts of the spectrum are compared.

Chahine, M. T.; Haskins, R.; Susskind, J.; Reuter, D.

1985-01-01

73

Determining the parameters of the potential of intermolecular interaction by the Zeno line  

NASA Astrophysics Data System (ADS)

The method of determination of intermolecular interaction potential parameters by the Zeno line is proposed. The intermolecular interaction of ethane, propane, ethylene, and propylene is described using a model of site-site interactions and Karr-Konowalow potential. It is shown that the parameters of intermolecular interaction for this potential can be determined from a small number of experimental data in the single-phase area. It is noted that the final parameters allow us to describe the thermodynamic properties over a broad range of gas and liquid states with precision acceptable for practical use.

Anashkin, I. P.; Klinov, A. V.

2013-11-01

74

Net growth delay: a novel parameter derived from tumor growth curves  

SciTech Connect

Growth delay does not only reflect the effect of treatment on the tumor parenchymal cells but also on the stroma. Due to tumor bed effect, the extent of growth delay determined from tumor growth curves is highly dependent on the end volume chosen. It was aimed to minimize the influence of the tumor bed effect on the growth delay calculated by choosing a smaller size and essentially an earlier time for regrowth. Net growth delay is a novel parameter derived from the tumor growth curves, allowing a better comparison of the results with colony assay and tumor control data.

Beck-Bornholdt, H.P.; Wuerschmidt, F.V.; Vogler, H.

1987-05-01

75

Sensitivity derivatives for advanced CFD algorithm and viscous modelling parameters via automatic differentiation  

NASA Technical Reports Server (NTRS)

The computational technique of automatic differentiation (AD) is applied to a three-dimensional thin-layer Navier-Stokes multigrid flow solver to assess the feasibility and computational impact of obtaining exact sensitivity derivatives typical of those needed for sensitivity analyses. Calculations are performed for an ONERA M6 wing in transonic flow with both the Baldwin-Lomax and Johnson-King turbulence models. The wing lift, drag, and pitching moment coefficients are differentiated with respect to two different groups of input parameters. The first group consists of the second- and fourth-order damping coefficients of the computational algorithm, whereas the second group consists of two parameters in the viscous turbulent flow physics modelling. Results obtained via AD are compared, for both accuracy and computational efficiency with the results obtained with divided differences (DD). The AD results are accurate, extremely simple to obtain, and show significant computational advantage over those obtained by DD for some cases.

Green, Lawrence L.; Newman, Perry A.; Haigler, Kara J.

1993-01-01

76

Effects of membrane physical parameters on hematoporphyrin-derivative binding to liposomes: a spectroscopic study  

SciTech Connect

Physical parameters of membrane bilayers were studied for their effect on the binding of hematoporphyrin derivative (Hpd), which is used as a sensitizer in photodynamic therapy of cancerous tissues. The purpose of this study was to clarify which parameters were relevant, under physiological conditions, to the selectivity of Hpd binding to cancer cells. Fluorescence spectroscopy was used to measure the relative partitioning of the dye between the lipid and aqueous media. Increasing the microviscosity of the liposomes' membranes by various bilayer additives results in a strong reduction of Hpd binding, to an extent independent of the specific additive. The effect of temperature near the physiological value as well as the effect of cross membrane potential are small. Surface potential does not affect the binding constant, indicating that the binding species does not carry a net electric charge.

Gross, E.; Malik, Z.; Ehrenberg, B.

1987-01-01

77

Determination of phenological parameters from MODIS derived NDVI data using hidden Markov models  

NASA Astrophysics Data System (ADS)

The phenological characteristics of the vegetation are key elements for understanding vegetation responses in different climate change scenarios, as well as indicators of ongoing processes of increasing aridity. Determination of phenological parameters for different types of vegetation in large areas help evaluate current and future impacts of climate change in ecosystems, specially in those more vulnerable. Moderate resolution remote sensing data, as provided by MODIS, has already been used to extract phenological characteristics from time series data of vegetation indices, most usually by data smoothing and fitting of polynomial models. In this work, we use hidden Markov models (HMMs) to define phenological parameters from MODIS derived NDVI time series data in a semiarid Mediterranean region. Different types of HMMs are applied in selected areas with well-defined vegetation communities, and their potentials for automatic phenological analysis at large scale are discussed.

García, Miguel A.; Moutahir, Hassane; Bautista, Susana; Rodríguez, Francisco

2014-08-01

78

Estimation of atomic interaction parameters by photon counting  

NASA Astrophysics Data System (ADS)

Detection of radiation signals is at the heart of precision metrology and sensing. In this article we show how the fluctuations in photon-counting signals can be exploited to optimally extract information about the physical parameters that govern the dynamics of the emitter. For a simple two-level emitter subject to photon counting, we show that the Fisher information and the Cramér-Rao sensitivity bound based on the full detection record can be evaluated from the waiting-time distribution in the fluorescence signal which can, in turn, be calculated for both perfect and imperfect detectors by a quantum trajectory analysis. We provide an optimal estimator achieving that bound.

Kiilerich, Alexander Holm; Mølmer, Klaus

2014-05-01

79

Novel polypyrrole derivatives to enhance conductive polymer-tissue interactions  

E-print Network

Developing materials that interact effectively with surrounding tissue is a major obstacle in sensor and drug delivery research. The body's natural immune response prevents foreign objects from easily integrating with an ...

George, Paul M. (Paul Matthew)

2005-01-01

80

Constraints on light neutrino parameters derived from the study of neutrinoless double beta decay  

E-print Network

The study of the neutrinoless double beta ($0 \\beta\\beta$) decay mode can provide us with important information on the neutrino properties, particularly on the electron neutrino absolute mass. In this work we revise the present constraints on the neutrino mass parameters derived from the $0 \\beta\\beta$ decay analysis of the experimentally interesting nuclei. We use the latest results for the phase space factors (PSFs) and nuclear matrix elements (NMEs), as well as for the experimental lifetimes limits. For the PSFs we use values computed with an improved method reported very recently. For the NMEs we use values chosen from literature on a case-by-case basis, taking advantage of the consensus reached by the community on several nuclear ingredients used in their calculation. Thus, we try to restrict the range of spread of the NME values calculated with di?erent methods and, hence, to reduce the uncertainty in deriving limits for the Majorana neutrino mass parameter. Our results may be useful to have an up-date ...

Stoica, Sabin

2014-01-01

81

Constraints on light neutrino parameters derived from the study of neutrinoless double beta decay  

E-print Network

The study of the neutrinoless double beta ($0 \\beta\\beta$) decay mode can provide us with important information on the neutrino properties, particularly on the electron neutrino absolute mass. In this work we revise the present constraints on the neutrino mass parameters derived from the $0 \\beta\\beta$ decay analysis of the experimentally interesting nuclei. We use the latest results for the phase space factors (PSFs) and nuclear matrix elements (NMEs), as well as for the experimental lifetimes limits. For the PSFs we use values computed with an improved method reported very recently. For the NMEs we use values chosen from literature on a case-by-case basis, taking advantage of the consensus reached by the community on several nuclear ingredients used in their calculation. Thus, we try to restrict the range of spread of the NME values calculated with di?erent methods and, hence, to reduce the uncertainty in deriving limits for the Majorana neutrino mass parameter. Our results may be useful to have an up-date image on the present neutrino mass sensitivities associated with $0 \\beta\\beta$ measurements for different isotopes and to better estimate the range of values of the neutrino masses that can be explored in the future double beta decay (DBD) experiments.

Sabin Stoica; Andrei Neacsu

2014-05-02

82

Interaction of fluorescently labeled triethyleneglycol and peptide derivatives with ?-cyclodextrin.  

PubMed

A triethyleneglycol (TEG) chain, a linear peptide, and a cyclic peptide labeled with 7-methoxycoumarin-3-carboxylic acid (MC) and 7-diethylaminocoumarin-3-carboxylic acid (DAC) were used to thoroughly study Förster resonance energy transfer (FRET) in inclusion complexes. (1) H NMR evidence was given for the formation of a 1:1 inclusion complex between ?-cyclodextrin (?-CD) and the fluorophore moieties of model compounds. The binding constant was 20 times higher for DAC than for MC derivatives. Molecular modeling provided additional information. The UV/Vis absorption and fluorescence properties were studied and the energy transfer process was quantified. Fluorescence quenching was particularly strong for the peptide derivatives. The presence of ?-CDs reduced the FRET efficiency slightly. Dye-labeled peptide derivatives can thus be used to form inclusion complexes with ?-CDs and retain most of their FRET properties. This paves the way for their subsequent use in analytical devices that are designed to measure the activity of matrix metalloproteinases. PMID:24402887

Alouini, Mohamed-Anis; Moustoifa, El-Farouck; Rubio-Albenque, Sandra; Berthelot, Thomas; Fery-Forgues, Suzanne; Déléris, Gérard

2014-02-24

83

Use of Factorial Analysis to Determine the Interaction Between Parameters of a Land Surface Model  

NASA Astrophysics Data System (ADS)

Land surface models use several parameters to represent biophysical processes. These parameters frequently are unknown, reproducing with uncertainty the characteristics of the ecosystem in study. Model calibration techniques find values for each parameter that reduce uncertainty. However, the calibration process is computationally expensive, since is necessary a lot of model runs to have their parameters adjusted. The more parameters are considered, more difficult the process is, particularly when there are interactions among them, and a modification in a parameter value implies in the change of the optimum value of the other parameters. The use of a factorial experiment allows the identification of possible inert parameters, whose values do not influence the final result of the experiment and, therefore, could be excluded from the calibration process. In this work we used factorial analysis to verify the existence of interaction among 5 parameters of the land surface IBIS model - Beta2 (distribution of fine roots), Vmax (maximum Rubisco enzyme capacity), m (coefficient related to the stomatal conductance), CHS (heat capacity of stems) and CHU (heat capacity of leaves) - evaluated against the output fluxes Rn (net radiation), H (sensible heat flux), LE (latent heat flux) and NEE (net ecosystem CO2 exchange). Data was collected at the Amazon tropical rainforest site known as K83, near Santarem, Brazil. The knowledge of the existing interactions between the parameters can considerably reduce the computational cost of further optimization processes, since each parameter that does not interact with others should be optimized independently.

Varejão, C. G.; Varejão, E. V.; Costa, M. H.

2007-05-01

84

Ultrasonographic fetal parameters and neonatal survival in somatic cell nuclear transfer-derived beef calves.  

PubMed

The objectives of this study were to identify prognostic indicators of calf survival in SCNT-derived beef calves. Ultrasonographic parameters of fetal well-being and development, maternal clinical parameters, and neonatal parameters were evaluated as predictors of calf survival in cows carrying SCNT-derived beef fetuses (n = 38). Calf survival was 61.5% (88.2% female and 40.9% male calves; P = 0.0026). Cow respiratory rate and cow temperature were significantly greater in the nonsurviving (NS) group 1 week prepartum. In surviving (S) calves, fetal heart rate (FHR) decreased during the last 2 weeks of gestation (P < 0.01). However, this final deceleration was not observed in NS calves, resulting in higher FHRs in this group (P < 0.0001). Fetal movement and fluid scores did not differ with calf classification. Mean amniotic fluid depth was smaller in S (5.5 ± 0.7 cm) than NS (8.7 ± 1.4 cm) calves (P = 0.0398). However, mean allantoic fluid depth did not differ (P = 0.6120). There was a significant association between the body weight of calf and the diameter of the fetal aorta (P = 0.0115; r(2) = 0.3762). Surviving calves were lighter at birth (P = 0.0028) and were born later (P = 0.007) than NS calves. Calves born vaginally had a smaller fetal aorta (2.1 ± 0.1 cm vaginal and 2.4 ± 0.1 cm Cesarean) (P = 0.0487) and a lighter birth weight (41.4 ± 4.2 kg vaginal and 60.4 ± 2.1 kg Cesarean) (P = 0.0001) than calves born by Cesarean. Also, calves that underwent spontaneous labor (52.2% S and 0% NS; P = 0.0029) had a lighter birth weight (44.9 ± 3.8 kg) than calves that did not initiate labor (61.6 ± 2.2 kg) (P = 0.0004). Frequent ultrasonographic fetal monitoring allowed identification of differences between S and NS calves. Calves without a final decrease in FHR or with a large aortic diameter were more likely to require a Cesarean because of failure to initiate labor or fetomaternal disproportion. Parameters of fetal well-being and development during the last 3 weeks of gestation were first described in SCNT-derived beef calves. PMID:25107630

Ferrer, M S; Miesner, M; Anderson, D E; Rousseau, M; Sardoy, M C

2014-10-01

85

Improving evapotranspiration in land surface models by using biophysical parameters derived from MSG/SEVIRI satellite  

NASA Astrophysics Data System (ADS)

Vegetation parameters derived from the geostationary satellite MSG/SEVIRI have been distributed at a daily frequency since 2007 over Europe, Africa and part of South America, through the LSA-SAF (http://landsaf.meteo.pt/). We propose here a method to handle two new remote sensing products from LSA-SAF, leaf area index and Fractional Vegetation Cover, noted LAI and FVC respectively, for land surface models at MSG/SEVIRI scale. The developed method relies on an ordinary least-square technique and a land cover map to estimate LAI for each model plant functional types of the model spatial unit. The method is conceived to be applicable for near-real time applications at continental scale. Compared to monthly vegetation parameters from a vegetation database commonly used in numerical weather predictions (ECOCLIMAP-I), the new remote sensing products allows a better monitoring of the spatial and temporal variability of the vegetation, including inter-annual signals, and a decreased uncertainty on LAI to be input into land surface models. We assess the impact of using LSA-SAF vegetation parameters compared to ECOCLIMAP-I in the land surface model H-TESSEL at MSG/SEVIRI spatial scale. Comparison with in-situ observations in Europe and Africa shows that the results on evapotranspiration are mostly improved, and especially in semi-arid climates. At last, the use of LSA-SAF and ECOCLIMAP-I is compared with simulations over a North-South Transect in Western Africa using LSA-SAF radiation forcing derived from remote sensing, and differences are highlighted.

Ghilain, N.; Arboleda, A.; Sepulcre-Cantò, G.; Batelaan, O.; Ardö, J.; Gellens-Meulenberghs, F.

2012-04-01

86

Improving evapotranspiration in land surface models by using biophysical parameters derived from MSG/SEVIRI satellite  

NASA Astrophysics Data System (ADS)

Vegetation parameters derived from the geostationary satellite MSG/SEVIRI have been distributed at a daily frequency since 2007 over Europe, Africa and part of South America, through the LSA-SAF facility. We propose here a method to handle two new remote sensing products from LSA-SAF, leaf area index and Fractional Vegetation Cover, noted LAI and FVC respectively, for land surface models at MSG/SEVIRI scale. The developed method relies on an ordinary least-square technique and a land cover map to estimate LAI for each model plant functional types of the model spatial unit. The method is conceived to be applicable for near-real time applications at continental scale. Compared to monthly vegetation parameters from a vegetation database commonly used in numerical weather predictions (ECOCLIMAP-I), the new remote sensing products allows a better monitoring of the spatial and temporal variability of the vegetation, including inter-annual signals, and a decreased uncertainty on LAI to be input into land surface models. We assess the impact of using LSA-SAF vegetation parameters compared to ECOCLIMAP-I in the land surface model H-TESSEL at MSG/SEVIRI scale. Comparison with in-situ observations in Europe and Africa shows that the results on evapotranspiration are mostly improved, and especially in semi-arid climates. At last, the use of LSA-SAF and ECOCLIMAP-I is compared with simulations over a North-South Transect in Western Africa using LSA-SAF radiation forcing derived from remote sensing, and differences are highlighted.

Ghilain, N.; Arboleda, A.; Sepulcre-Cantò, G.; Batelaan, O.; Ardö, J.; Gellens-Meulenberghs, F.

2011-10-01

87

Parameter Evaluation of a Simple Mean-Field Model of Social Interaction  

E-print Network

The aim of this work is to implement a statistical mechanics theory of social interaction, generalizing econometric discrete choice models. A class of simple mean field discrete models is introduced and discussed both from the theoretical and phenomenological point of view. We propose a parameter evaluation procedure and test it by fitting our model against three families of data coming from different cases: the estimated interaction parameters are found to have similar positive values establishing a quantitative confirmation of the peer imitation behavior found in social psychology. Moreover all the values of the interaction parameters belong to the phase transition regime suggesting its possible role in the study of social systems.

Ignacio Gallo; Adriano Barra; Pierluigi Contucci

2008-10-16

88

Studies on the interactions of 3,6-diaminoacridine derivatives with human serum albumin by fluorescence spectroscopy.  

PubMed

This study reports the preparation and investigation of the modes of binding of the two symmetric 3,6-diaminoacridine derivatives obtained from proflavine, which are 3,6-diphenoxycarbonyl aminoacridine and 3,6-diethoxycarbonyl aminoacridine to human serum albumin (HSA). The interaction of HSA with the derivatives was investigated using fluorescence quenching and ultraviolet-visible absorption spectra at pH 7.2 and different temperatures. The results suggest that the derivatives used can interact strongly with HSA and are the formation of HSA-derivative complexes and hydrophobic interactions as the predominant intermolecular forces in stabilizing for each complex. The Stern-Volmer quenching constants, binding constants, binding sites and corresponding thermodynamic parameters ?H, ?S and ?G were calculated at different temperatures. The binding distance (r)?~?3 nm between the donor (HSA) and acceptors (3,6-diethoxycarbonyl aminoacridine, 3,6-diphenoxycarbonyl aminoacridine and proflavine) was obtained according to Förster's non-radiative energy transfer theory. Moreover, the limit of detection and limit of quantification of derivatives were calculated in the presence of albumin. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24616283

Göko?lu, Elmas; K?pçak, Fulya; Sefero?lu, Zeynel

2014-11-01

89

SITE SPECIFIC REFERENCE PERSON PARAMETERS AND DERIVED CONCENTRATION STANDARDS FOR THE SAVANNAH RIVER SITE  

SciTech Connect

The purpose of this report is twofold. The first is to develop a set of behavioral parameters for a reference person specific for the Savannah River Site (SRS) such that the parameters can be used to determine dose to members of the public in compliance with Department of Energy (DOE) Order 458.1 “Radiation Protection of the Public and the Environment.” A reference person is a hypothetical, gender and age aggregation of human physical and physiological characteristics arrived at by international consensus for the purpose of standardizing radiation dose calculations. DOE O 458.1 states that compliance with the annual dose limit of 100 mrem (1 mSv) to a member of the public may be demonstrated by calculating the dose to the maximally exposed individual (MEI) or to a representative person. Historically, for dose compliance, SRS has used the MEI concept, which uses adult dose coefficients and adult male usage parameters. Beginning with the 2012 annual site environmental report, SRS will be using the representative person concept for dose compliance. The dose to a representative person will be based on 1) the SRS-specific reference person usage parameters at the 95th percentile of appropriate national or regional data, which are documented in this report, 2) the reference person (gender and age averaged) ingestion and inhalation dose coefficients provided in DOE Derived Concentration Technical Standard (DOE-STD-1196-2011), and 3) the external dose coefficients provided in the DC_PAK3 toolbox. The second purpose of this report is to develop SRS-specific derived concentration standards (DCSs) for all applicable food ingestion pathways, ground shine, and water submersion. The DCS is the concentration of a particular radionuclide in water, in air, or on the ground that results in a member of the public receiving 100 mrem (1 mSv) effective dose following continuous exposure for one year. In DOE-STD-1196-2011, DCSs were developed for the ingestion of water, inhalation of air and submersion in air pathways, only. These DCSs are required by DOE O 458.1 to be used at all DOE sites in the design and conduct of radiological environmental protection programs. In this report, DCSs for the following additional pathways were considered and documented: ingestion of meat, dairy, grains, produce (fruits and vegetables), seafood, submersion in water and ground shine. These additional DCSs were developed using the same methods as in DOE-STD-1196-2011 and will be used at SRS, where appropriate, as screening and reference values.

Jannik, T.

2013-03-14

90

Deriving structural parameters of semi-resolved star clusters. FitClust: a program for crowded fields  

E-print Network

Context. An automatic tool to derive structural parameters of semi-resolved star clusters located in crowded stellar fields in nearby galaxies is needed for homogeneous processing of archival frames. Aims. We have developed a program that automatically derives the structural parameters of star clusters and estimates errors by accounting for individual stars and variable sky background. Methods. Models of observed frames consist of the cluster's surface brightness distribution, convolved with a point spread function; the stars, represented by the same point spread function; and a smoothly variable sky background. The cluster's model is fitted within a large radius by using the Levenberg-Marquardt and Markov chain Monte Carlo algorithms to derive structural parameters, the flux of the cluster, and individual fluxes of all well-resolved stars. Results. FitClust, a program to derive structural parameters of semi-resolved clusters in crowded stellar fields, was developed and is available for free use. The program ...

Narbutis, D; Stonkut?, R; de Meulenaer, P; Mineikis, T; Bridžius, A; Vansevi?ius, V

2014-01-01

91

Improving mesoscale modeling using satellite-derived land surface parameters in the Pearl River Delta region, China  

NASA Astrophysics Data System (ADS)

surface parameters play an important role in mesoscale modeling by regulating the regional heat flux and hydrological cycle. Recently, significant urbanization and afforestation occurred in the Pearl River Delta (PRD) region, China, which exert an important effect on local meteorology and thermal circulation. But previous studies failed to capture the complex changes of the surface characteristics in the PRD and thus were difficult to accurately describe the land-atmosphere coupling. In this study, high-resolution Moderate Resolution Imaging Spectroradiometer observations are used to specify the land cover type, green vegetation fraction, and leaf area index in the Weather Research and Forecasting model. Comparisons with ground-based observations during eight episodes, as well as satellite measurements, all indicate an improved model performance when the satellite-derived land surface parameters are assimilated. Moreover, the remote sensing data accurately reflect the surface inhomogeneity and successfully represent the intensity and spatiotemporal characteristics of the urban heat island (UHI) effect. The UHI effect in turn modifies the local thermal circulation by enhancing the urban-rural horizontal advection and initiating the urban heat island circulation, as well as interacting with the sea/land breeze over the PRD. This work not only improves the understanding of local meteorological simulation and forecasting but also sets the stage for further research on the feedback between air quality and meteorological responses due to land cover changes.

Li, Mengmeng; Song, Yu; Huang, Xin; Li, Jianfeng; Mao, Yi; Zhu, Tong; Cai, Xuhui; Liu, Bing

2014-06-01

92

ELECTRONIC FACTOR IN QSAR: MO-PARAMETERS, COMPETING INTERACTIONS, REACTIVITY AND TOXICITY  

EPA Science Inventory

Reactive chemicals pose unique problems in the development of SAR and QSAR in environmental chemistry and toxicology. odels of the stereoelectronic interactions of reactive toxicants with biological systems require formulation of parameters that quantify the electronic structure ...

93

Shifts of neutrino oscillation parameters in reactor antineutrino experiments with non-standard interactions  

NASA Astrophysics Data System (ADS)

We discuss reactor antineutrino oscillations with non-standard interactions (NSIs) at the neutrino production and detection processes. The neutrino oscillation probability is calculated with a parametrization of the NSI parameters by splitting them into the averages and differences of the production and detection processes respectively. The average parts induce constant shifts of the neutrino mixing angles from their true values, and the difference parts can generate the energy (and baseline) dependent corrections to the initial mass-squared differences. We stress that only the shifts of mass-squared differences are measurable in reactor antineutrino experiments. Taking Jiangmen Underground Neutrino Observatory (JUNO) as an example, we analyze how NSIs influence the standard neutrino measurements and to what extent we can constrain the NSI parameters. Long baseline reactor antineutrino experiments, such as KamLAND [10,11]. The aim of these experiments is to observe the slow oscillation with ?21 and measure the corresponding oscillation parameters ?m212 and ?12. Short baseline reactor antineutrino experiments, such as Daya Bay [1-3], Double CHOOZ [4], RENO [5]. They are designed to observe the fast oscillation with ?31 and ?32 (or equivalently, ?ee[3]) and measure the corresponding oscillation parameters ?mee2, ?13. Medium baseline reactor antineutrino experiments. They stand for the next generation experiments of reactor antineutrinos, with typical representatives of Jiangmen Underground Neutrino Observatory (JUNO) [12] and RENO-50 [13]. They can determine the neutrino mass ordering (m1interactions (NSIs) [14,15]. They induce effective four-fermion interactions after integrating out some heavy particles beyond the SM, where the heavy particles can be scalars, pseudo-scalars, vectors, axial-vectors, or tensors [16]. For reactor antineutrino experiments NSIs may appear in the antineutrino production and detection processes, and can modify the neutrino oscillation probability. Therefore, the neutrino mixing angles and mass-squared differences can be shifted and the mass ordering (MO) measurement will be affected. There are some previous discussions on NSIs in reactor antineutrino experiments [17-19] and other types of oscillation experiments [20]. In this work, we study the NSI effect in reactor antineutrino oscillations in both specific models and also the most general case. Taking JUNO as an example, we apply our general framework to the medium baseline reactor antineutrino experiment. We discuss how NSIs influence the standard 3-generation neutrino oscillation measurements and to what extent we can constrain the NSI parameters.The remaining part of this work is organized as follows. Section 2 is to derive the analytical formalism. We develop a general framework on the NSI effect in reaction antineutrino oscillations, and calculate the neutrino survival probability in the presence of NSIs. In Section 3, we give the numerical analysis for the JUNO experiment. We analyze the NSI impacts on the precision measurement of mass-squared differences and the determination of the neutrino mass ordering, and present the JUNO sensitivity of the relevant NSI parameters. Finally, we conclude in Section 4.

Li, Yu-Feng; Zhou, Ye-Ling

2014-11-01

94

Sounding-derived parameters associated with tornado occurrence in Poland and Universal Tornadic Index  

NASA Astrophysics Data System (ADS)

This study is mainly devoted to operational meteorology, to improve tornado forecast in Poland and create a Universal Tornadic Index formula. A study is focusing on climatology of sounding-derived parameters associated with tornadoes in Poland and their potential value for tornado forecasting. The data was collected from soundings made in 10 stations in and around Poland which were closely in time and space connected with tornado occurrence. The main aim of the study was to analyze the thermodynamic and kinematic parameters derived from soundings and formulate an index. The information about tornado incidents was taken from media reports and the European Severe Weather Database for the years 1977-2012. Total of 97 tornado cases were divided according to their strength for significant (F2/F3), weak (F0/F1) and unrated cases, and also according to their environmental surface temperature, for warm (> 18 °C) and cold (< 18 °C) tornadoes. As it turned out, depending on the temperature, tornadoes tended to present different environmental conditions for tornadogenesis. In warm cases, the most important factor was instability while for cold cases it was dynamic wind field. It was also proven that significant tornadoes in Poland occur in conditions accompanied by high moisture content, moderate instability and high wind shear conditions. The results of this study were used to create a Universal Tornadic Index designed to forecast activity in warm and cold, and weak and strong tornadic environments. The quality of this index was tested for the period with increased tornado activity in Poland from 2008 to 2010.

Taszarek, M.; Kolendowicz, L.

2013-12-01

95

Regionalization of subsurface stormflow parameters of hydrologic models: Derivation from regional analysis of streamflow recession curves  

NASA Astrophysics Data System (ADS)

Subsurface stormflow is an important component of the rainfall-runoff response, especially in steep terrain. Its contribution to total runoff is, however, poorly represented in the current generation of land surface models. The lack of physical basis of these common parameterizations precludes a priori estimation of the stormflow (i.e. without calibration), which is a major drawback for prediction in ungauged basins, or for use in global land surface models. This paper is aimed at deriving regionalized parameterizations of the storage-discharge relationship relating to subsurface stormflow from a top-down empirical data analysis of streamflow recession curves extracted from 50 eastern United States catchments. Detailed regression analyses were performed between parameters of the empirical storage-discharge relationships and the controlling climate, soil and topographic characteristics. The regression analyses performed on empirical recession curves at catchment scale indicated that the coefficient of the power-law form storage-discharge relationship is closely related to the catchment hydrologic characteristics, which is consistent with the hydraulic theory derived mainly at the hillslope scale. As for the exponent, besides the role of field scale soil hydraulic properties as suggested by hydraulic theory, it is found to be more strongly affected by climate (aridity) at the catchment scale. At a fundamental level these results point to the need for more detailed exploration of the co-dependence of soil, vegetation and topography with climate.

Ye, Sheng; Li, Hong-Yi; Huang, Maoyi; Ali, Melkamu; Leng, Guoyong; Leung, L. Ruby; Wang, Shao-wen; Sivapalan, Murugesu

2014-11-01

96

[The effect of taurine derivative of change the biochemical parameters carbohidrate and lipide status by starvation].  

PubMed

The results obtained on the model of starvation shows that nutritional dropsy led to the significant decrease of glucose, total cholesterol (TCh) and triglycerides (TC), as well as increase of non-estherified fatty acids (NEFA) in blood serum. In the rats with nutritional dropsy after treatment fed with standard diet enriched with soybean protein body weight returned to normal values as well as levels of Glucose, TCh and TC. However, concentration of NEFA remained increased. In the experimental group received additionally taurepar or taurhythman the level of NEFA decreased up to the normal one. It is necessary to mention that taurine derivatives did not change the biochemical parameters in blood of normal non-starved rats. We suppose that these new substances promote reduction of intensity of hyperlipidemic processes. It is known, that during starvation incomplete oxidation of fatty acids leads to acidosis with following destruction of mitochondria membraine. Finding property of taurine derivatives to decrease the concentration of non-estherified fatty acids points at their ability for restoration of tricarboxilic acid's cycle and prevention of accumulation of suboxidized molecules of NEFA and acidosis development. PMID:20853619

Khnychenko, L K; Sapronov, N S

2010-01-01

97

Resolution dependence of petrophysical parameters derived from X-ray tomography of chalk  

NASA Astrophysics Data System (ADS)

X-ray computed tomography data from chalk drill cuttings were taken over a series of voxel dimensions, ranging from 320 to 25 nm. From these data sets, standard petrophysical parameters (porosity, surface area, and permeability) were derived and we examined the effect of the voxel dimension (i.e., image resolution) on these properties. We found that for the higher voxel dimensions, they are severely over or underestimated, whereas for 50 and 25 nm voxel dimension, the resulting values (5%-30% porosity, 0.2-2 m2/g specific surface area, and 0.06-0.34 mD permeability) are within the expected range for this type of rock. We compared our results to macroscopic measurements and in the case of surface area, also to measurements using the Brunauer-Emmett-Teller (BET) method and found that independent of the degree of compaction, the results from tomography amount to about 30% of the BET method. Finally, we concluded that at 25 nm voxel dimension, the essential features of the nanoscopic pore network in chalk are captured but better resolution is still needed to derive surface area.

Müter, D.; Sørensen, H. O.; Jha, D.; Harti, R.; Dalby, K. N.; Suhonen, H.; Feidenhans'l, R.; Engstrøm, F.; Stipp, S. L. S.

2014-07-01

98

A pathwise derivative approach to the computation of parameter sensitivities in discrete stochastic chemical systems.  

PubMed

Characterizing the sensitivity to infinitesimally small perturbations in parameters is a powerful tool for the analysis, modeling, and design of chemical reaction networks. Sensitivity analysis of networks modeled using stochastic chemical kinetics, in which a probabilistic description is used to characterize the inherent randomness of the system, is commonly performed using Monte Carlo methods. Monte Carlo methods require large numbers of stochastic simulations in order to generate accurate statistics, which is usually computationally demanding or in some cases altogether impractical due to the overwhelming computational cost. In this work, we address this problem by presenting the regularized pathwise derivative method for efficient sensitivity analysis. By considering a regularized sensitivity problem and using the random time change description for Markov processes, we are able to construct a sensitivity estimator based on pathwise differentiation (also known as infinitesimal perturbation analysis) that is valid for many problems in stochastic chemical kinetics. The theoretical justification for the method is discussed, and a numerical algorithm is provided to permit straightforward implementation of the method. We show using numerical examples that the new regularized pathwise derivative method (1) is able to accurately estimate the sensitivities for many realistic problems and path functionals, and (2) in many cases outperforms alternative sensitivity methods, including the Girsanov likelihood ratio estimator and common reaction path finite difference method. In fact, we observe that the variance reduction using the regularized pathwise derivative method can be as large as ten orders of magnitude in certain cases, permitting much more efficient sensitivity analysis than is possible using other methods. PMID:22280752

Sheppard, Patrick W; Rathinam, Muruhan; Khammash, Mustafa

2012-01-21

99

ON THE COMPOSITION-DEPENDENT INTERACTION PARAMETERS IN EQUATIONS OF STATE  

Microsoft Academic Search

Composition-dependent interaction parameters have been applied to the calculation of vapor-liquid equilibria (VLE) in mixtures containing components of different chemical nature. Binary VLE have been correlated and ternary VLE have been predicted from binary data using five different mixing rules. Binary data can be accurately correlated for systems with moderate deviations from ideality using mixing rules with two binary parameters.

MA?GORZATA ?ENCKA; ANDRZEJ ANDERKO

1991-01-01

100

Spin and spin-isospin instabilities and Landau parameters of Skyrme interactions with tensor correlations  

SciTech Connect

The Landau parameters of Skyrme interactions in the spin and spin-isospin channels are studied using various Skyrme effective interactions with and without tensor correlations. We focus on the role of the tensor terms on the spin and spin-isospin instabilities that can occur in nuclear matter above saturation density. We point out that these instabilities are realized in nuclear matter at the critical density of about two times the saturation density for all the adopted parameter sets. The critical density is shown to be very much dependent not only on the choice of the Skyrme parameter set, but also on the inclusion of the tensor terms.

Cao Ligang [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000 (China); Dipartimento di Fisica, Universita degli Studi di Milano, via Celoria 16, Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, Milano (Italy); Colo, Gianluca [Dipartimento di Fisica, Universita degli Studi di Milano, via Celoria 16, Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, Milano (Italy); Sagawa, Hiroyuki [Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8560 (Japan)

2010-04-15

101

Some special derived radar parameters and their development during the life cycle of different thunderstorm types  

NASA Astrophysics Data System (ADS)

Data from a C-Band Doppler Radar - located in Southwestern Germany - was used to track different isolated thunderstorms in order to investigate their 4-dimensional developments. This study concentrates especially on the development of some bulk properties, which were calculated from the reflectivity data points that are supposed to represent the thunderstorm. In order to separate the reflectivity data of the investigated thunderstorm from the background and to obtain this data in subsequent datasets the tracking algorithm TRACE3D was used. TRACE3D thereby identifies thunderstorms as continuous regions of strong reflectivities and tracks them in time, giving access to the total life cycle of observed storms. For a further investigation of the development of the storms we defined - next to 'often' used properties like the total volume, the maximum reflectivity, the velocity of a storms' reference point, the total liquid water content and others - some abstract properties like a 'reflectivity mass' as a reflectivity weighted volume, the height of the center of gravity of the thunderstorms' volume and reflectivity mass and some special ratios. These last parameters are also evaluated in relation to some specific, the convective environment representing heights like the level of free convection (LFC), the 0°C and the -10°C level, which were extracted from data of operational upper air rawind soundings. In this presentation the development of the special derived radar parameters of a strong multicell storm and a damaging hail developing supercell are compared. The track of the multicell storm lasted 130 min. and covered a distance of 65 km, whereas the examined track of the supercell lasted for 170 min. and covered a distance of 109 km. Especially the parameters, that are related to the levels of isotherms (0°C, 10°C) as well as to the LFC showed distinct differences. It was found, for example, that for the supercell thunderstorms the height of the center of gravity of the thunderstorms' volume and reflectivity mass were located during the entire period above the 0°C level and showed just a slight oscillation. In the case of the thunderstorms' volume the height was even located above the -10°C level for a considerably long period (after which - by the way - large hail was reported). The multicell thunderstorm on the other hand indicated a pronounced oscillation of the parameters over significantly greater distances and only relatively short crossings of different levels of isotherms by a new updraft pulse within the regular multicell life cycle. It thus seems that the height of the center of gravity above a specific level and the time it remains there can serve as a distinction between the storm types and indicate a short-term development.

Neuper, Malte; Handwerker, Jan; Beheng, Klaus D.

2014-05-01

102

QuickBird derived vegetation parameters for soil erosion risk assessment in an alpine catchment  

NASA Astrophysics Data System (ADS)

The focus of soil erosion research in the Alps has been in two categories: (i) on-site measurements which are rather small scale point measurements on selected plots often constrained to irrigation experiments or (ii) off-site quantification of sediment delivery at the outlet of the catchment. Results of both categories showed that an intact vegetation cover prevents soil loss. With the recent availability of high-resolution satellites such as IKONOS and QuickBird options for detecting and monitoring of vegetation parameters have increased. The aim of this study is to evaluate the usefulness of QuickBird derived vegetation parameters in soil erosion models by comparison to Cesium-137 (Cs-137) soil erosion estimates. The study site (67km2) is located in the Central Swiss Alps and is dominated by grasslands with strong anthropogenic influences due to farming for centuries. Linear spectral unmixing and supervised classification is applied to produce maps of fractional vegetation cover (FVC) for grasslands and detailed land-cover maps from QuickBird imagery. The maps are used to adapt the C factor, which accounts for land management in the Universal Soil Loss Equation (USLE). Further the data was introduced to the Pan-European Soil Erosion Risk Assessment (PESERA) model. Supervised land-cover classification yielded a total accuracy of 93.3%. Linear spectral unmixing of vegetation abundance showed a significant (at the 0.01 level) correlation to ground truth FVC. Both models yielded higher absolute soil erosion estimates and an improvement of spatial patterns when FVC and a detailed land-cover maps are considered. However, discrepancies between model estimates and Cs-137 erosion estimates remained, especially for the PESERA model. This is leading to the assumption that soil erosion processes not considered in the models, e.g. soil erosion caused by snow gliding, play a decisive role.

Meusburger, Katrin; Konz, Nadine; Schaub, Monika; Alewell, Christine

2010-05-01

103

Intermolecular interactions between imidazole derivatives intercalated in layered solids. Substituent group effect  

SciTech Connect

This study sheds light on the intermolecular interactions between imidazole derive molecules (2-methyl-imidazole, 2-ethyl-imidazole and benzimidazole) intercalated in T[Ni(CN){sub 4}] layers to form a solid of formula unit T(ImD){sub 2}[Ni(CN){sub 4}]. These hybrid inorganic–organic solids were prepared by soft chemical routes and their crystal structures solved and refined from X-ray powder diffraction data. The involved imidazole derivative molecules were found coordinated through the pyridinic N atom to the axial positions for the metal T in the T[Ni(CN){sub 4}] layer. In the interlayers region ligand molecules from neighboring layers remain stacked in a face-to-face configuration through dipole–dipole and quadrupole–quadrupole interactions. These intermolecular interactions show a pronounced dependence on the substituent group and are responsible for an ImD-pillaring concatenation of adjacent layers. This is supported by the structural information and the recorded magnetic data in the 2–300 K temperature range. The samples containing Co and Ni are characterized by presence of spin–orbit coupling and pronounced temperature dependence for the effective magnetic moment except for 2-ethyl-imidazole related to the local distortion for the metal coordination environment. For this last one ligand a weak ferromagnetic ordering ascribed to a super-exchange interaction between T metals from neighboring layers through the ligands ?–? interaction was detected. - Graphical abstract: In the interlayers region imidazole derivative molecules are oriented according to their dipolar and quadrupolar interactions and minimizing the steric impediment. Highlights: • Imidazole derivatives intercalation compounds. • Intermolecular interaction between intercalated imidazole derivatives. • Hybrid inorganic–organic solids. • Pi–pi interactions and ferromagnetic coupling. • Dipolar and quadrupolar interactions between intercalated imidazole derivatives.

González, M.; Lemus-Santana, A.A. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Rodríguez-Hernández, J. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Instituto de Ciencia y Tecnología de Materiales, Universidad de La Habana, Havana (Cuba); Aguirre-Velez, C.I. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Knobel, M. [Institute of Physics “Gleb Wataghin”, UNICAMP, 13083-970 Campinas, SP (Brazil); Reguera, E., E-mail: edilso.reguera@gmail.com [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico)

2013-08-15

104

The Atlas of Vesta Spectral Parameters derived from the mapping spectrometer VIR onboard NASA/Dawn  

NASA Astrophysics Data System (ADS)

From 2011 to 2012 the Visible and Infrared Mapping Spectrometer (VIR) onboard NASA/Dawn spacecraft has mapped the surface of Vesta from three different orbital heights, acquiring infrared and visible spectra from 0.2 to 5 microns, sampled in 864 channels with a spatial resolution up to about 150 m/pixel. From the large amount of spectra retrieved we have derived spectral parameters which can be combined to identify specific physical and compositional states. To start with, we have computed the band center and depth for band I and band II of pyroxenes. Pyroxene's band center I and II are commonly associated with a compositional variation. For example, orthopyroxene bands shift towards longer wavelengths with increasing amounts of iron, while clinopyroxene bands shift towards longer wavelengths with increasing calcium content. Band depths are related to scattering effects, associated to the abundance and the grain size of the absorber. Mapping these parameters on the surface allow to detect terrain units compositions and physical-state in their stratigraphic context. We have produced an atlas of digital maps, projected following the 15-quadrangle scheme commonly adopted for small sized planetary bodies. The digital maps have geospatial metadata and are available in GIS and other scientific programming language formats. A special imagery product has been produced, where the geomorphologic context from the Framing Camera, and the IAU nomenclature have been added to the mineralogic maps. This way we have both quantitative digital maps and print-ready maps. Digital maps are useful in statistical and geo-processing studies, while print-ready maps represent an easy to be consulted high-level data products. As with the atlas we are combining data acquired at very different observing geometries and in different phases of the mission, filtering has been necessary and an iterative process to project data produces results that are incrementally more consistent as we detect and exclude source of artifacts. At the moment of writing, the atlas has reached version 2.0, and most likely it will be updated by fall with an improved version. Moreover, the current number of 56 maps will increase as soon as new parameters, or a combination of them, will be added to the atlas.

Frigeri, A.; De Sanctis, M.; Ammannito, E.; Tosi, F.; Capria, M.; Capaccioni, F.; Zambon, F.; Palomba, E.; Magni, G.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

2013-12-01

105

Connection between Dynamically Derived Initial Mass Function Normalization and Stellar Population Parameters  

NASA Astrophysics Data System (ADS)

We report on empirical trends between the dynamically determined stellar initial mass function (IMF) and stellar population properties for a complete, volume-limited sample of 260 early-type galaxies from the ATLAS3D project. We study trends between our dynamically derived IMF normalization ?dyn ? (M/L)stars/(M/L)Salp and absorption line strengths, and interpret these via single stellar population-equivalent ages, abundance ratios (measured as [?/Fe]), and total metallicity, [Z/H]. We find that old and alpha-enhanced galaxies tend to have on average heavier (Salpeter-like) mass normalization of the IMF, but stellar population does not appear to be a good predictor of the IMF, with a large range of ?dyn at a given population parameter. As a result, we find weak ?dyn-[?/Fe] and ?dyn -Age correlations and no significant ?dyn -[Z/H] correlation. The observed trends appear significantly weaker than those reported in studies that measure the IMF normalization via the low-mass star demographics inferred through stellar spectral analysis.

McDermid, Richard M.; Cappellari, Michele; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Bureau, Martin; Crocker, Alison F.; Davies, Roger L.; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnovi?, Davor; Kuntschner, Harald; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M.

2014-09-01

106

High-resolution polar climate parameters derived from 1-km AVHRR data  

SciTech Connect

This paper describes the development of a time-series of composites of albedo, surface temperature, and sea ice motion. The composites will be generated from high-resolution (Local Area Coverage and High Resolution Picture Transmission) Advanced Very High Resolution Radiometer (AVHRR). Composites of albedo and surface (skin) temperature will be derived from AVHRR data within three hours of two selected local times (0400 and 1400 for the northern hemisphere, and 0200 and 1600 for the southern hemisphere) for each day. These products will be gridded at 1.25 km cell size in an equal-area projection compatible with recent gridded products from Special Sensor Microwave/Imager data and planned products from the TIROS Operational Verticle Sounder and other AVHRR data sets. Sea ice motion will be calculated once per day by comparing clear-sky image data of sea ice over a three-day period, and reported on a 1.25 km grid. A brief discussion of a reconnaissance survey of the output geophysical parameters for the Northern Hemisphere between August and October 1993 is also presented. 9 refs., 5 figs., 2 tabs.

Hutchinson, T.A.; Scambos, T.A. [Univ. of Colorado, Boulder, CO (United States)

1997-11-01

107

Deriving structural parameters of semi-resolved star clusters. FitClust: a program for crowded fields  

NASA Astrophysics Data System (ADS)

Context. An automatic tool to derive structural parameters of semi-resolved star clusters located in crowded stellar fields in nearby galaxies is needed for homogeneous processing of archival frames. Aims: We have developed a program that automatically derives the structural parameters of star clusters and estimates errors by accounting for individual stars and variable sky background. Methods: Models of observed frames consist of the cluster's surface brightness distribution, convolved with a point spread function; the stars, represented by the same point spread function; and a smoothly variable sky background. The cluster's model is fitted within a large radius by using the Levenberg-Marquardt and Markov chain Monte Carlo algorithms to derive structural parameters, the flux of the cluster, and individual fluxes of all well-resolved stars. Results: FitClust, a program to derive structural parameters of semi-resolved clusters in crowded stellar fields, was developed and is available for free use. The program was tested on simulated cluster frames, and was used to measure clusters of the M31 galaxy in Subaru Suprime-Cam frames. Conclusions: Accounting for bright resolved stars and variable sky background significantly improves the accuracy of derived structural parameters of star clusters. However, their uncertainty remains dominated by the stochastic noise of unresolved stars.

Narbutis, D.; Semionov, D.; Stonkut?, R.; de Meulenaer, P.; Mineikis, T.; Bridžius, A.; Vansevi?ius, V.

2014-09-01

108

A data base for polymer chromatography: temperature dependence of interaction parameters in liquid adsorption chromatography.  

PubMed

The temperature dependence of retention behaviour of polyethylene glycol (PEG) and its mono- and dimethyl ethers was studied on various RP columns in different mobile phases. The accessible volumes and the interaction parameters were determined from slope and intercept in a plot of the elution volumes of the oligomers of a polymer homologous series as a function of the difference of the elution volumes of consecutive oligomers. A quite different dependence of the interaction parameters was observed in the different mobile phases. While in methanol-water the interaction parameter decreases with increasing temperature, the opposite effect is observed in acetonitrile (ACN)-water. In acetone-water, the temperature dependence is almost negligible. PMID:19714653

Trathnigg, Bernd; Cuong, Nguyen Viet; Ahmed, Hasnat

2009-09-01

109

Crystal lattice properties fully determine short-range interaction parameters for alkali and halide ions.  

PubMed

Accurate models of alkali and halide ions in aqueous solution are necessary for computer simulations of a broad variety of systems. Previous efforts to develop ion force fields have generally focused on reproducing experimental measurements of aqueous solution properties such as hydration free energies and ion-water distribution functions. This dependency limits transferability of the resulting parameters because of the variety and known limitations of water models. We present a solvent-independent approach to calibrating ion parameters based exclusively on crystal lattice properties. Our procedure relies on minimization of lattice sums to calculate lattice energies and interionic distances instead of equilibrium ensemble simulations of dense fluids. The gain in computational efficiency enables simultaneous optimization of all parameters for Li+, Na+, K+, Rb+, Cs+, F-, Cl-, Br-, and I- subject to constraints that enforce consistency with periodic table trends. We demonstrate the method by presenting lattice-derived parameters for the primitive model and the Lennard-Jones model with Lorentz-Berthelot mixing rules. The resulting parameters successfully reproduce the lattice properties used to derive them and are free from the influence of any water model. To assess the transferability of the Lennard-Jones parameters to aqueous systems, we used them to estimate hydration free energies and found that the results were in quantitative agreement with experimentally measured values. These lattice-derived parameters are applicable in simulations where coupling of ion parameters to a particular solvent model is undesirable. The simplicity and low computational demands of the calibration procedure make it suitable for parametrization of crystallizable ions in a variety of force fields. PMID:22897252

Mao, Albert H; Pappu, Rohit V

2012-08-14

110

Entanglement dynamics in two-parameter qubit-qutrit states under Dzyaloshinskii-Moriya interaction  

NASA Astrophysics Data System (ADS)

We study entanglement dynamics in two-parameter qubit-qutrit states under the influence of Dzyaloshisnhkii-Moriya (DM) interaction. Our system consists of a qubit-qutrit pair as a closed system initially in two-parameter class of states, and one environmental qubit interacts with the qutrit of the closed system via DM interaction. We divide our analysis into two cases. In the first case, we study the entanglement dynamics in separable region, and in the second case we study the same in non-separable region. The DM interaction produces the entanglement in separable region with entanglement sudden death (ESD) and some states in this region remain unaffected by the same. In non-separable region, all the states are affected by DM interaction. The DM interaction excites the entanglement but does not produce ESD in this region. We observed that probability amplitude of environmental qubit does not affect the entanglement in two-parameter qubit-qutrit states in both the regions.

Sharma, Kapil K.; Pandey, S. N.

2014-09-01

111

Analysis and validation of severe storm parameters derived from TITAN in Southeast Brazil  

NASA Astrophysics Data System (ADS)

The implementation of TITAN (Thundestorm Identification, Tracking and Nowcasting) System at IPMet in December 2005 has provided real-time access to the storm severity parameters derived from radar reflectivity, which are being used to identify and alert of potentially severe storms within the 240 km quantitative ranges of the Bauru and Presidente Prudente S-band radars. The potential of these tools available with the TITAN system is being evaluated by using the hail reports received from voluntary hail observers to cross-check the occurrence of hail within the radar range against the TITAN predictions. Part of the ongoing research at IPMet aims to determine "signatures" in severe events and therefore, as from 2008, an online standard form was introduced, allowing for greater detail on the occurrence of a severe event within the 240 km ranges of both radars. The model for the hail report was based on the one initially deployed by the Alberta Hail Program, in Canada, and also by the Hail Observer Network established by the CSIR (Council for Scientific and Industrial Research), in Pretoria, South Africa, where it was used for more than 25 years. The TITAN system was deployed to obtain the tracking properties of storms for this analysis. A cell was defined by the thresholds of 40 dBZ for the reflectivity and 16 km3 for the volume, observed at least in two consecutive volume scans (15 minutes). Besides tracking and Nowcasting the movement of storm cells, TITAN comprises algorithms that allow the identification of potentially severe storm "signatures", such as the hail metrics, to indicate the probability of hail (POH), based on a combination of radar data and the knowledge of the vertical temperature distribution of the atmosphere. Another two parameters, also related to hail producing storms, called FOKR (Foote-Krauss) index and HMA (Hail Mass Aloft) index is also included. The period from 2008 to 2013 was used to process all available information about storm characteristics, such as, onset time, duration and size of hail. The results of the analysis for the time evolution of the storm cells properties enabled the identification of the following key signatures for hail-producing cells: storm volume varying between at least 250 km3 and 1850 km3; average speed of more than 50 km/h; FOKR and POH indices with values between 3 and 4 and 0,8 to 1, respectively, observed at the same time as hail was reported to have fallen on the ground; HMA parameters (mass of hail accumulated aloft) peaking between 80 tons and 808 tons, preceding the time of the hail observed on the ground. The onset of hail, indicated in the reports, corroborates the time near the observed collapse of the cell indicated by a decreasing value of the severity indices provided by TITAN. This ongoing research will add more cases to include not only hail-producing cells, but also those associated with extreme winds and flash floods, to contribute towards the improvement of IPMet's radar bulletins issued routinely by the operational sector for the private and public sector, like the Civil Defense Authorities of the state of São Paulo.

Gomes, Ana Maria; Held, Gerhard; Vernini, Rafael; Demetrio Souza, Caio

2014-05-01

112

QSAR Analysis for ADA upon Interaction with a Series of Adenine Derivatives as Inhibitors  

Microsoft Academic Search

The kinetic parameters of adenosine deaminase such as Km and Ki were determined in the absence and presence of adenine derivatives (R1–R24) in sodium phosphate buffer (50 mM; pH 7.5) solution at 27°C. These kinetic parameters were used for QSAR analysis. As such, we found some theoretical descriptors to which the binding affinity of adenosine deaminase (ADA) towards several adenine

S. Safarian; G. H. Hakimelahi; G. Ataei; D. Ajloo; S. Panjehpour; S. Riahi; M. F. Mousavi; S. Mardanyan; N. Soltani; H. Sharghi; H. Moghadamnia; A. A. Saboury

2004-01-01

113

Compost mixture influence of interactive physical parameters on microbial kinetics and substrate fractionation  

E-print Network

Compost mixture influence of interactive physical parameters on microbial kinetics and substrate 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 Composting is a feasible by selecting an initial compost recipe with physical properties that enhance microbial activity. The present

Paris-Sud XI, Université de

114

Identification of self consistent field interaction parameter from continuum Monte Carlo simulation of model polymer blends  

NASA Astrophysics Data System (ADS)

Monte Carlo simulations of binary AB polymer blends have been performed to evaluate the effective interaction parameter ?e of self consistent field theory, and to quantify corrections to RPA predictions for fluctuations. We consider a model with a non-bonded pair interaction vij(r) = ?ijf(r) for which f(r) is of the repulsive Lennard-Jones form, ?AA=?BB, and ?AB= ?AA+ ??. Using thermodynamic perturbation theory, to first order in ??, we obtain an interaction free energy with the composition dependence predicted by Flory-Huggins theory, with an effective interaction parameter ?e= ??zc. Here, zc is an effective coordination number given by the average of the sum of values of f(r) for interactions between a test monomer and nearby monomers on other chains, in a reference system with ??=0. Results for composition fluctuations in semigrand ensemble simulations of blends with a range of values of ??!=0, for several chain lengths, are compared to RPA predictions calculated using this perturbatively defined ?e parameter.

Chung, Jun Kyung; Morse, David

2008-03-01

115

An enhanced and automated approach for deriving a priori SAC-SMA parameters from the soil survey geographic database  

Microsoft Academic Search

This paper presents an automated approach for processing the Soil Survey Geographic (SSURGO) Database and the National Land Cover Database (NLCD), and deriving gridded a priori parameters for the National Weather Service (NWS) Sacramento Soil Moisture Accounting (SAC-SMA) model from these data sets. Our approach considerably extends methods previously used in the NWS and offers automated and geographically invariant ways

Yu Zhang; Ziya Zhang; Seann Reed; Victor Koren

2011-01-01

116

Upper-crustal scattering parameters as derived from induced micro-seismicity and acoustic log data  

NASA Astrophysics Data System (ADS)

In deterministic seismology it is assumed, that each inhomogeneity within the traversed medium causes a travel time shift and/or special phase in the observed seismogram. This information may then be used to analyze the properties of the inhomogeneity (e.g. location, size). However, this method is only successful for inhomogeneities larger than the station separation, the Fresnel zone and the wavelength. In the Earth's curst there exist many small-scale heterogeneities. Stochastic models can be used to determine the most important statistical parameters of the small-scale inhomogeneities neglecting their exact locations. In high-frequency seismograms (> 1 Hz) information on heterogeneity and seismic absorption is reflected by wave trains following the direct wave featuring decreasing amplitude with increasing lapse time, know as Coda waves. Since seismic wave propagation through a heterogeneous and absorbing medium is an extremely complex process, it has become common practice to use seismogram envelopes instead of complete waveforms to gain insight in the attenuation properties. Besides the manifestation in high-frequency seismograms information on heterogeneity can be extracted from well-logs. Borehole measurements provide detailed 1D information on the distribution of elastic properties within the upper crust at scales from about one meter to several kilometers. Strong random fluctuations in seismic velocity having short wavelengths superposed on a step-like structure represent here the deterministic and stochastic components of the crustal structure. These observations suggest a description of the crust as a random medium with a broad spectrum of heterogeneity. In the framework of developing techniques for the estimation of attenuation properties in geothermal reservoirs, as part of the German research program Geothermal Energy and High-performance Drilling (gebo), seismogram envelope inversion and statistical analysis of acoustic logs have been applied to data from the German Continental Deep Drilling (KTB) project. In the present research a passive seismic data set is considered which was acquired during a long-term hydraulic fracturing treatment at the KTB in 2000. Induced seismicity was recorded with a temporal seismic network, consisting of 40 stations, at epicentral distances less than 20 km. Processed seismic events have magnitudes Ml ˜ 1.0. Acoustic log data comprise the P- and S-wave velocity distribution logged in two boreholes. In the pilot borehole continuous data reach from the surface (28 m) to a depth of approx. 4000 m, while for the main borehole coherent logs are available between 285 m and 7160 m. Scattering and intrinsic attenuation, derived from micro-seismic events at the KTB, reasonably match regional attenuation models for Southern Germany. In contrast, scattering strength estimated from acoustic log data exceeds the regional attenuation models by one order of magnitude. The scattering coefficient shows weak but almost identical frequency dependence for both types of analysis that is best-described by a power-law form. From the frequency dependence it can be inferred that a von Kármán-type of random medium is a good model for representing the fractured geothermal reservoir at the KTB. The estimated Hurst exponent, related to the scattering coefficient, is also in good agreement with reference values derived for the upper crust.

Fielitz, Daniel; Wegler, Ulrich

2013-04-01

117

Derivation of site-specific relationships between hydraulic parameters and p-wave velocities based on hydraulic and seismic tomography  

SciTech Connect

In this study, hydraulic and seismic tomographic measurements were used to derive a site-specific relationship between the geophysical parameter p-wave velocity and the hydraulic parameters, diffusivity and specific storage. Our field study includes diffusivity tomograms derived from hydraulic travel time tomography, specific storage tomograms, derived from hydraulic attenuation tomography, and p-wave velocity tomograms, derived from seismic tomography. The tomographic inversion was performed in all three cases with the SIRT (Simultaneous Iterative Reconstruction Technique) algorithm, using a ray tracing technique with curved trajectories. The experimental set-up was designed such that the p-wave velocity tomogram overlaps the hydraulic tomograms by half. The experiments were performed at a wellcharacterized sand and gravel aquifer, located in the Leine River valley near Göttingen, Germany. Access to the shallow subsurface was provided by direct-push technology. The high spatial resolution of hydraulic and seismic tomography was exploited to derive representative site-specific relationships between the hydraulic and geophysical parameters, based on the area where geophysical and hydraulic tests were performed. The transformation of the p-wave velocities into hydraulic properties was undertaken using a k-means cluster analysis. Results demonstrate that the combination of hydraulic and geophysical tomographic data is a promising approach to improve hydrogeophysical site characterization.

Brauchler, R.; Doetsch, J.; Dietrich, P.; Sauter, M.

2012-01-10

118

Accelerated expansion from non-linear derivative interaction and Gauss-Bonnet invariant  

Microsoft Academic Search

We discuss in this letter a new cosmological model including both a non-linear derivative interaction and a Gauss-Bonnet invariant. The first interaction term appears in the theory with the Galilean shift symmetry, whereas the second term is motivated from string theory and plays a crucial role in Chern-Simons gravitational theories as well as in the renormalization of quantum field theories

Ahmad Rami El-Nabulsi

2010-01-01

119

Method qualification and application of diffusion interaction parameter and virial coefficient.  

PubMed

This research focused on evaluation and application of two methods in studying weak protein-protein interactions, i.e. diffusion interaction parameter (KD) and second virial coefficient (B22), both of which are first-order coefficients of protein interactions. Although the plate-based KD method successfully distinguished KD values with relatively large difference in a pH ranging study, it failed to make a consistent statistical decision to determine close interactions as shown by the comprehensive ANOVA analysis. We also validated the DLS-based B22 method by using a model protein lysozyme. The dramatic change of solution appearance for lysozyme as a function of NaCl concentration highlighted the importance of B22 in understanding protein interactions. Moreover, B22 measurement for a MAb fragment suggested a more repulsive protein interaction in histidine buffer than in citrate buffer. The coefficient of variation was <10% when B22 was on an order of magnitude of 10(-4) L mmol/g(2) in contrast to >30% when it approached 10(-5) L mmol/g(2). In this research, we also made an attempt to study protein-protein interactions in concentrated MAb fragment solutions (e.g. >50 mg/mL). Our data suggested that such interactions could be empirically modeled by high-order virial expansions. PMID:24095715

Shi, Shuai; Uchida, Makiko; Cheung, Jason; Antochshuk, Valentyn; Shameem, Mohammed

2013-11-01

120

Self-Assembled Fullerene-Derivative Monolayers on a Gold Substrate Using Phenanthroline-Au Interactions  

E-print Network

Self-Assembled Fullerene-Derivative Monolayers on a Gold Substrate Using Phenanthroline iodide. Reaction of this intermediate with C60 in refluxing toluene resulted in the formation) surface.7 Presumably, both the interaction between the pyridyl nitrogens and the gold surface as well

Tao, Nongjian

121

An enhanced and automated approach for deriving a priori SAC-SMA parameters from the soil survey geographic database  

NASA Astrophysics Data System (ADS)

This paper presents an automated approach for processing the Soil Survey Geographic (SSURGO) Database and the National Land Cover Database (NLCD), and deriving gridded a priori parameters for the National Weather Service (NWS) Sacramento Soil Moisture Accounting (SAC-SMA) model from these data sets. Our approach considerably extends methods previously used in the NWS and offers automated and geographically invariant ways of extracting soil information, interpreting soil texture, and spatially aggregating SAC-SMA parameters. The methodology is composed of four components. The first and second components are SSURGO and NLCD preprocessors. The third component is a parameter generator producing SAC-SMA parameters for each soil survey area on an approximately 30-m grid mesh. The last component is a postprocessor creating parameters for user-specified areas of interest on the Hydrologic Rainfall Analysis Project (HRAP) grid. Implemented in open-source software, this approach was employed by creating a set of SAC-SMA parameter and related soil property grids spanning 25 states, wherein it was shown to greatly reduce the derivation time and meanwhile yield results comparable to those based on the State Soil Geographic Database (STATSGO). The broad applicability of the methodologies and associated intermediate products to hydrologic modeling is discussed.

Zhang, Yu; Zhang, Ziya; Reed, Seann; Koren, Victor

2011-02-01

122

Structural Interface Parameters Are Discriminatory in Recognising Near-Native Poses of Protein-Protein Interactions  

PubMed Central

Interactions at the molecular level in the cellular environment play a very crucial role in maintaining the physiological functioning of the cell. These molecular interactions exist at varied levels viz. protein-protein interactions, protein-nucleic acid interactions or protein-small molecules interactions. Presently in the field, these interactions and their mechanisms mark intensively studied areas. Molecular interactions can also be studied computationally using the approach named as Molecular Docking. Molecular docking employs search algorithms to predict the possible conformations for interacting partners and then calculates interaction energies. However, docking proposes number of solutions as different docked poses and hence offers a serious challenge to identify the native (or near native) structures from the pool of these docked poses. Here, we propose a rigorous scoring scheme called DockScore which can be used to rank the docked poses and identify the best docked pose out of many as proposed by docking algorithm employed. The scoring identifies the optimal interactions between the two protein partners utilising various features of the putative interface like area, short contacts, conservation, spatial clustering and the presence of positively charged and hydrophobic residues. DockScore was first trained on a set of 30 protein-protein complexes to determine the weights for different parameters. Subsequently, we tested the scoring scheme on 30 different protein-protein complexes and native or near-native structure were assigned the top rank from a pool of docked poses in 26 of the tested cases. We tested the ability of DockScore to discriminate likely dimer interactions that differ substantially within a homologous family and also demonstrate that DOCKSCORE can distinguish correct pose for all 10 recent CAPRI targets. PMID:24498255

Malhotra, Sony; Sankar, Kannan; Sowdhamini, Ramanathan

2014-01-01

123

Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions  

PubMed Central

Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Results Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. Conclusions The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions. PMID:23151272

2012-01-01

124

Testing a Two-temperature Model of the Solar Corona with Empirically-derived Plasma parameters  

NASA Astrophysics Data System (ADS)

We compare the plasma parameters predicted from the Michigan two-temperature chromosphere-corona model to those parameters obtained from the analyses of UVCS and LASCO data. The empirical data are organized as Carrington rotation maps for the electron densities, proton kinetic temperatures, and outflow velocities. This data format makes it convenient for understanding the differences between the modeled and observed latitudinal variations in the plasma parameters. In addition, we discuss the model performance for characterizing streamers and coronal holes at different phases in the solar activity cycle. These tests are useful for investigating how well coronal and solar wind models simulate the underlying physical processes that operate in the solar corona.

Strachan, L.; Panasyuk, A.; Lamy, P. L.; van der Holst, B.; Oran, R.; Frazin, R. A.; Manchester, W. B.

2012-12-01

125

Interacting two-component fluid models with varying EoS parameter  

E-print Network

In this paper, we consider Universe filled with two-component fluid. We study two different models. In the first model we assume barotropic fluid with the linear equation of state as the first component of total fluid. In the second model we assume Van der Waals gas as the first component of total fluid. In both models, the second component assumed generalized ghost dark energy. We consider also interaction between component and discuss, numerically, cosmological quantities for two different parametrization of EoS which varies with time. We consider this as a toy model of our Universe. We fix parameters of the model by using generalized second law of thermodynamics. Comparing our results with some observational data suggests interacting barotropic fluid with EoS parameter $\\omega(t)=\\omega_{0}\\cos(tH)+\\omega_{1}t\\frac{\\dot{H}}{H}$ and generalized ghost dark energy as an appropriate model to describe our Universe.

M. Khurshudyan; B. Pourhassan; E. O. Kahya

2013-12-02

126

Comparison of photon interaction parameters of some tissues and their substitutes.  

PubMed

The photon interaction parameters such as mass attenuation coefficient (?/?), effective atomic number (Z eff) and effective electron density (N el) must be identical for the phantom material and their tissue. In the present study, the ?/?, Z eff, and N el for muscle, breast, lung tissue have been computed, and their substitutes such as Griffith muscle, Griffith breast, Griffith lung, Alderson muscle A, Alderson muscle, and Alderson lung. Also compared were ?/?, Z eff, and N el for muscle, breast, lung tissue, and their substitutes. It can be shown that Alderson muscle B is better substitute for muscle than Griffith muscle and Alderson muscle A. Similarly, the photon interaction parameters of tissue substitutes of lung and breast with their original tissue were also compared. PMID:24378560

Manjunatha, H C

2014-02-01

127

Signal intensities derived from different NMR probes and parameters contribute to variations in quantification of metabolites.  

PubMed

We discovered that serious issues could arise that may complicate interpretation of metabolomic data when identical samples are analyzed at more than one NMR facility, or using slightly different NMR parameters on the same instrument. This is important because cross-center validation metabolomics studies are essential for the reliable application of metabolomics to clinical biomarker discovery. To test the reproducibility of quantified metabolite data at multiple sites, technical replicates of urine samples were assayed by 1D-(1)H-NMR at the University of Alberta and the University of Michigan. Urine samples were obtained from healthy controls under a standard operating procedure for collection and processing. Subsequent analysis using standard statistical techniques revealed that quantitative data across sites can be achieved, but also that previously unrecognized NMR parameter differences can dramatically and widely perturb results. We present here a confirmed validation of NMR analysis at two sites, and report the range and magnitude that common NMR parameters involved in solvent suppression can have on quantitated metabolomics data. Specifically, saturation power levels greatly influenced peak height intensities in a frequency-dependent manner for a number of metabolites, which markedly impacted the quantification of metabolites. We also investigated other NMR parameters to determine their effects on further quantitative accuracy and precision. Collectively, these findings highlight the importance of and need for consistent use of NMR parameter settings within and across centers in order to generate reliable, reproducible quantified NMR metabolomics data. PMID:24465670

Lacy, Paige; McKay, Ryan T; Finkel, Michael; Karnovsky, Alla; Woehler, Scott; Lewis, Michael J; Chang, David; Stringer, Kathleen A

2014-01-01

128

Signal Intensities Derived from Different NMR Probes and Parameters Contribute to Variations in Quantification of Metabolites  

PubMed Central

We discovered that serious issues could arise that may complicate interpretation of metabolomic data when identical samples are analyzed at more than one NMR facility, or using slightly different NMR parameters on the same instrument. This is important because cross-center validation metabolomics studies are essential for the reliable application of metabolomics to clinical biomarker discovery. To test the reproducibility of quantified metabolite data at multiple sites, technical replicates of urine samples were assayed by 1D-1H-NMR at the University of Alberta and the University of Michigan. Urine samples were obtained from healthy controls under a standard operating procedure for collection and processing. Subsequent analysis using standard statistical techniques revealed that quantitative data across sites can be achieved, but also that previously unrecognized NMR parameter differences can dramatically and widely perturb results. We present here a confirmed validation of NMR analysis at two sites, and report the range and magnitude that common NMR parameters involved in solvent suppression can have on quantitated metabolomics data. Specifically, saturation power levels greatly influenced peak height intensities in a frequency-dependent manner for a number of metabolites, which markedly impacted the quantification of metabolites. We also investigated other NMR parameters to determine their effects on further quantitative accuracy and precision. Collectively, these findings highlight the importance of and need for consistent use of NMR parameter settings within and across centers in order to generate reliable, reproducible quantified NMR metabolomics data. PMID:24465670

Finkel, Michael; Karnovsky, Alla; Woehler, Scott; Lewis, Michael J.; Chang, David; Stringer, Kathleen A.

2014-01-01

129

Application of lab derived kinetic biodegradation parameters at the field scale  

Microsoft Academic Search

Estimating the intrinsic remediation potential of an aquifer typically requires the accurate assessment of the biodegradation kinetics, the level of available electron acceptors and the flow field. Zero- and first-order degradation rates derived at the laboratory scale generally overpredict the rate of biodegradation when applied to the field scale, because limited electron acceptor availability and microbial growth are typically not

M. Schirmer; J. F. Barker; B. J. Butler; E. O. Frind

2003-01-01

130

Analysing spatio-temporal footprints of urbanization on environment of Surat city using satellite-derived bio-physical parameters  

Microsoft Academic Search

Our study examines the relationships among various environmental variables in Surat city using remote sensing. Landsat Thematic Mapper satellite data were used in conjugation with geospatial techniques to study urbanization and correlation among satellite-derived biophysical parameters namely, normalized difference vegetation index (NDVI), normalized difference built-up index (NDBI), normalized difference water index (NDWI), normalized difference bareness index (NDBaI) and land surface

Richa Sharma; Aniruddha Ghosh; P. K. Joshi

2012-01-01

131

Novel Peptide-Mediated Interactions Derived from High-Resolution 3-Dimensional Structures  

PubMed Central

Many biological responses to intra- and extracellular stimuli are regulated through complex networks of transient protein interactions where a globular domain in one protein recognizes a linear peptide from another, creating a relatively small contact interface. These peptide stretches are often found in unstructured regions of proteins, and contain a consensus motif complementary to the interaction surface displayed by their binding partners. While most current methods for the de novo discovery of such motifs exploit their tendency to occur in disordered regions, our work here focuses on another observation: upon binding to their partner domain, motifs adopt a well-defined structure. Indeed, through the analysis of all peptide-mediated interactions of known high-resolution three-dimensional (3D) structure, we found that the structure of the peptide may be as characteristic as the consensus motif, and help identify target peptides even though they do not match the established patterns. Our analyses of the structural features of known motifs reveal that they tend to have a particular stretched and elongated structure, unlike most other peptides of the same length. Accordingly, we have implemented a strategy based on a Support Vector Machine that uses this features, along with other structure-encoded information about binding interfaces, to search the set of protein interactions of known 3D structure and to identify unnoticed peptide-mediated interactions among them. We have also derived consensus patterns for these interactions, whenever enough information was available, and compared our results with established linear motif patterns and their binding domains. Finally, to cross-validate our identification strategy, we scanned interactome networks from four model organisms with our newly derived patterns to see if any of them occurred more often than expected. Indeed, we found significant over-representations for 64 domain-motif interactions, 46 of which had not been described before, involving over 6,000 interactions in total for which we could suggest the molecular details determining the binding. PMID:20502673

Stein, Amelie; Aloy, Patrick

2010-01-01

132

Urban Heat Island Modeling in Conjunction with Satellite-Derived Surface\\/Soil Parameters  

Microsoft Academic Search

Although it has been studied for over 160 years, the urban heat island (UHI) effect is still not completely understood, yet it is increasingly important. The main purpose of this work is to improve UHI modeling by using AVHRR (Advanced Very High Resolution Radiometer) satellite data to retrieve the surface parameters (albedo, as well as soil thermal and moisture properties).

Jan Hafner; Stanley Q. Kidder

1999-01-01

133

CALIBRATION FOR THE SOLAR CHANNEL USING MODIS-DERIVED BRDF PARAMETERS OVER AUSTRALIAN DESERT TARGETS  

Microsoft Academic Search

Communication Ocean Meteorological Satellite (COMS) to be launched at 2008 will be the first Korean geostationary satellite. The Meteorological Imager (MI) aboard the COMS will measure the reflected solar radiation within a spectral band (550 ~ 800 nm) as well as emitted infrared radiation at 4 spectral bands. The retrieval of quantitative parameters requires the absolute calibration of the radiometer

Hyung-Wook Chun; Byung-Ju Sohn

134

Significance of kinematic plate parameters derived from actual satellite laser ranging data  

Microsoft Academic Search

Station coordinate shifts observed by satellite laser ranging are analyzed with respect to global plate kinematics. Under the geophysically founded assumption of rigid plates, uniform rotation vectors are estimated for all stations situated on the same plate. It is demonstrated that these parameters are not significant from the present-day data set. In a second step, inter-plate station movements are used

Hermann Drewes

1986-01-01

135

Photometric parameter maps of the Moon derived from LROC WAC images  

NASA Astrophysics Data System (ADS)

Spatially resolved photometric parameter maps were computed from 21 months of Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images. Due to a 60° field-of-view (FOV), the WAC achieves nearly global coverage of the Moon each month with more than 50% overlap from orbit-to-orbit. From the repeat observations at various viewing and illumination geometries, we calculated Hapke bidirectional reflectance model parameters [1] for 1°x1° "tiles" from 70°N to 70°S and 0°E to 360°E. About 66,000 WAC images acquired from February 2010 to October 2011 were converted from DN to radiance factor (I/F) though radiometric calibration, partitioned into gridded tiles, and stacked in a time series (tile-by-tile method [2]). Lighting geometries (phase, incidence, emission) were computed using the WAC digital terrain model (100 m/pixel) [3]. The Hapke parameters were obtained by model fitting against I/F within each tile. Among the 9 parameters of the Hapke model, we calculated 3 free parameters (w, b, and hs) by setting constant values for 4 parameters (Bco=0, hc=1, ?, ?=0) and interpolating 2 parameters (c, Bso). In this simplification, we ignored the Coherent Backscatter Opposition Effect (CBOE) to avoid competing CBOE and Shadow Hiding Opposition Effect (SHOE). We also assumed that surface regolith porosity is uniform across the Moon. The roughness parameter (?) was set to an averaged value from the equator (× 3°N). The Henyey-Greenstein double lobe function (H-G2) parameter (c) was given by the 'hockey stick' relation [4] (negative correlation) between b and c based on laboratory measurements. The amplitude of SHOE (Bso) was given by the correlation between w and Bso at the equator (× 3°N). Single scattering albedo (w) is strongly correlated to the photometrically normalized I/F, as expected. The c shows an inverse trend relative to b due to the 'hockey stick' relation. The parameter c is typically low for the maria (0.08×0.06) relative to the highlands (0.47×0.16). Since c controls the fraction of backward/forward scattering in H-G2, lower c for the maria indicates more forward scattering relative to the highlands. This trend is opposite to what was expected because darker particles are usually more backscattering. However, the lower albedo of the maria is due to the higher abundance of ilmenite, which is an opaque mineral that scatters all of the light by specular reflection from the its surface. If their surface facets are relatively smooth the ilmenite particles will be forward scattering. Other factors (e.g. grain shape, grain size, porosity, maturity) besides the mineralogy might also be affecting c. The angular-width of SHOE (hs) typically shows lower values (0.047×0.02) for the maria relative to the highlands (0.074×0.025). An increase in hs for the maria theoretically suggests lower porosity or a narrower grain size distribution [1], but the link between actual materials and hs is not well constrained. Further experiments using both laboratory and spacecraft observations will help to unravel the photometric properties of the surface materials of the Moon. [1] Hapke, B.: Cambridge Univ. Press, 2012. [2] Sato, H. et al.: 42nd LPSC, abstract #1974, 2011. [3] Scholten, F. et al.: JGR, 117, E00H17, 2012. [4] Hapke, B.: Icarus, 221(2), p1079-1083, 2012.

Sato, H.; Robinson, M. S.; Hapke, B. W.; Denevi, B. W.; Boyd, A. K.

2013-12-01

136

Comparison of Transport Parameters derived from Time-Lapse Electrical Resistivity Tomography, TDR and Effluent Break Through Curves  

NASA Astrophysics Data System (ADS)

During the recent years it was shown that time-lapse electrical resistivity tomography (ERT) has potential to image subsurface solute transport processes. In this study we captured the spatio-temporal evolution of an inert salt tracer plume by means of time-lapse ERT in an unsaturated undisturbed soil column (height: 1.4 m, diameter: 1.16 m). The experiment was performed two-fold for 2 different steady state flow conditions, respectively, corresponding to approximately 15 % and 55 % of saturation. The ERT data were inverted with a three dimensional, smoothness-constrained inversion algorithm based on finite-element modelling. Identical error parameters were used for all ERT inversions and experiments. The image time series provides spatially resolved break-through curves (BTCs). Simultaneously, the BTCs in the outflow were measured and local BTCs within the monolith were measured with TDR. Following a stream tube approach, effective transport parameters were obtained by fitting the convective-dispersive equation to all available break-through curves. However, due to the non-uniqueness of the ERT inversion, the parameters derived from time lapse ERT might not be robust. Therefore, we appraised their robustness by comparing them with parameters derived from effluent and TDR measured BTCs. For all break through experiments, the mean ERT derived effective velocities at the TDR positions matched the ones found by TDR with a mean deviation of app. 5 %. The ERT derived dispersivities exceeded the ones found by TDR by a factor of two or more for the upper soil layers. For the deeper soil layers where the electrical contrasts were smoothed by dispersion, ERT and TDR derived effective dispersivities converged. For the four experiments, the effective velocity which was obtained from the effluent BTC matched the mean of the velocities derived from the bottommost ERT voxels with accuracy of 2.5 % to 5.5 %. The dispersivities of the effluent BTCs could be predicted from the variance of the ERT voxel velocities and the mean ERT voxel dispersivities with an accordance of 2.5 % to 23.5 %. The results confirm that smoothness constraint time lapse ERT images can be interpreted quantitatively up to a certain degree. We expect that a greater accuracy could be achieved if time-lapse information was incorporated into the inversion algorithm or a hydro-geophysical joint inversion approach was used.

Koestel, J.; Kemna, A.; Javaux, M.; Vanderborght, J.; Binley, A.; Vereecken, H.

2007-05-01

137

Cooperative water-SOM interactions derived from the organic compound effect on SOM hydration  

NASA Astrophysics Data System (ADS)

Interactions of water molecules with soil organic matter (SOM) may affect the ability of SOM to participate in multiple physical, chemical and biological processes. Specifically, water-SOM interactions may have a profound effect on interactions of organic compounds with SOM which is often considered as a major natural sorbent controlling the environmental fate of organic pollutants in the soil environment. Quantification of water - SOM interactions may be carried out by using water vapor sorption isotherms. However, water sorption isotherms providing macroscopic thermodynamic data do not allow examining water-SOM interactions on a microenvironment scale. The examination of water-SOM interactions in a local SOM environment may be carried out by determining the response of the SOM hydration to sorption of probe organic compounds. Recently, the model-free approach was proposed which allows quantifying effects of sorbing organic molecules on water - SOM interactions, by using relatively more available data on the effect of water activity on organic compound - SOM interactions. Therefore, this thermodynamic approach was applied to the experimental data describing sorption of organic compounds by SOM, both from the vapor and liquid phases, at various water activities. Hence, the response of water interactions with the model SOM materials such as a humic acid and an organic matter-rich peat soil to the presence of various organic sorbates was evaluated. Depending on a molecular structure of organic sorbates probing various molecular environments in SOM, the SOM-bound water may be driven in or out of the SOM sorbents. Organic compounds containing the atoms of oxygen, nitrogen or sulfur and preferring a relatively "polar" SOM microenvironment demonstrate the distinct enhancing effect on water-SOM interactions. In contrast, the "low-polarity" organic compounds, e.g., hydrocarbons or their halogen-substituted derivatives, produce a weakening effect on water-SOM interactions. Importantly, the changes in water-SOM interactions induced by the presence of organic compounds may demonstrate the cooperative behavior: (1) several water molecules may be involved in an enhanced hydration of SOM, (2) at the presence of an organic sorbate, interactions of water molecules with SOM enhance the uptake of the following water molecules. The proposed cooperative water-SOM interactions may result from a perturbation of the SOM matrix due to a sorption of organic and water molecules where a partial disrupting of molecular contacts in SOM makes easier the following SOM-water interactions thus promoting the enhanced SOM hydration.

Borisover, Mikhail

2014-05-01

138

Study of DNA interactions with cyclic chalcone derivatives by spectroscopic techniques  

NASA Astrophysics Data System (ADS)

A series of chalcone derivatives ( 1- 4) were studied. The interaction between these ligands and calf thymus DNA was studied with UV-vis spectrophotometry, fluorescence and circular dichroism spectroscopy. The binding constants K were estimated at 0.5-4.6 × 10 5 M -1. All these measurements indicated that the compounds behave as effective DNA-intercalating agents. Electrophoretic separation proved that ligands inhibited topoisomerase I at a concentration of 60 ?M.

Štefanišinová, M.; Tome?ková, V.; Kožurková, M.; Ostró, A.; Mareková, M.

2011-10-01

139

Potential-derived point-charge model study of electrostatic interactions in DNA base components  

NASA Astrophysics Data System (ADS)

Ab initio electrostatic potentials obtained using STO-3G wavefunctions for guanine. cytosine adenine, and thymine are used to calculate potential-derived (PD) point charges for these base components. Calculated PD point charges are used to estimate the electrostatic contributions to hydrogen-bonding and stacking interaction energies of ten sequence isomers of B-DNA. These estimates are in excellent agreement with the results of the more elaborate segmental multipole moment expansion technique.

Ray, Naba K.; Shibata, Masayuki; Bolis, Giorgio; Rein, Robert

1984-08-01

140

Interaction of Salmonella typhi strains with cultured human monocyte-derived macrophages.  

PubMed Central

Human monocyte-derived macrophages (MDM) provided this laboratory with a tool to develop a primary-cell assay for evaluating the relative virulence of newly constructed Salmonella typhi carrier strains. In this study, the interaction with and survival within MDM were compared for delta aroA143-attenuated strains, wild-type virulent strains, and the current oral-vaccine strain, Ty21a. PMID:8975929

Sizemore, D R; Elsinghorst, E A; Eck, L C; Branstrom, A A; Hoover, D L; Warren, R L; Rubin, F A

1997-01-01

141

Evaluating the Spatio-Temporal Factors that Structure Network Parameters of Plant-Herbivore Interactions  

PubMed Central

Despite the dynamic nature of ecological interactions, most studies on species networks offer static representations of their structure, constraining our understanding of the ecological mechanisms involved in their spatio-temporal stability. This is the first study to evaluate plant-herbivore interaction networks on a small spatio-temporal scale. Specifically, we simultaneously assessed the effect of host plant availability, habitat complexity and seasonality on the structure of plant-herbivore networks in a coastal tropical ecosystem. Our results revealed that changes in the host plant community resulting from seasonality and habitat structure are reflected not only in the herbivore community, but also in the emergent properties (network parameters) of the plant-herbivore interaction network such as connectance, selectiveness and modularity. Habitat conditions and periods that are most stressful favored the presence of less selective and susceptible herbivore species, resulting in increased connectance within networks. In contrast, the high degree of selectivennes (i.e. interaction specialization) and modularity of the networks under less stressful conditions was promoted by the diversification in resource use by herbivores. By analyzing networks at a small spatio-temporal scale we identified the ecological factors structuring this network such as habitat complexity and seasonality. Our research offers new evidence on the role of abiotic and biotic factors in the variation of the properties of species interaction networks. PMID:25340790

Lopez-Carretero, Antonio; Diaz-Castelazo, Cecilia; Boege, Karina; Rico-Gray, Victor

2014-01-01

142

Influence of some physical parameters on sol-gel-derived TiO2 thin films  

Microsoft Academic Search

We present some physical parameters that affect the deposition of TiO2 films by the sol-gel method. A set of solutions with different TiO2 concentrations has been prepared. After synthesis of a set of TiO2 films by spin coating at different spinning speeds, the films were annealed at different temperatures. The viscosities of the start solutions were measured by a viscometer.

S. M. Attia; Jue Wang; Jun Shen; Guangming Wu; Qinyuan Zhang; Zhenquan Lai; Tianhe Yang

2000-01-01

143

Effects of Gaussian perturbations on parameter estimators derived from an estimated signal subspace  

Microsoft Academic Search

The authors present theoretical analyses that are appropriate for both high and low signal-to-noise ratio (SNR) of signal subspace or SVD-based signal-processing algorithms. For the low-SNR case, the probability of obtaining an outlier is calculated and is used to determine the threshold SNR at which the variance of parameter estimation errors departs from Cramer-Rao bound behavior. At high-SNR, the perturbation

A. C. Kot; C. D. Melissinos; D. W. Tufts; R. J. Vaccaro

1988-01-01

144

Electronic polarizability, optical basicity, and interaction parameter of La2O3 and related glasses  

NASA Astrophysics Data System (ADS)

The electronic polarizability and optical basicity of La2O3 and related glasses have been determined from ultraviolet absorption spectra and calculations based on the Lorentz-Lorenz equation. The optical basicity for La2O3 oxide is found to be 1.07, being much larger compared with typical glass-forming oxides such as B2O3 (0.42) and SiO2 (0.48) but being similar to heavy element oxides such as TeO2 (0.93). The Yamashita and Kurosawa's interaction parameter of La2O3 is 0.03 Å-3, indicating that La2O3 is classified as a normal ionic (basic) oxide, i.e., an ionic bonding character in the La3+-O bond is proposed. Close correlations are confirmed among optical basicity, interaction parameter, and oxygen 1s binding energy in x-ray photoelectron (XPS) spectra for La2O3-P2O5 and other La2O3-containing glasses. It is found from XPS and Raman spectra that La3+ ions in La2O3-P2O5 glasses act as network modifiers, supporting an ionic bonding character in the La3+-O bond. The parameters related to electronic polarizability in La2O3 determined in the present study would be useful for the design of rare-earth containing optical functional glasses.

Honma, T.; Benino, Y.; Fujiwara, T.; Komatsu, T.; Sato, R.; Dimitrov, V.

2002-03-01

145

Five organic salts assembled from carboxylic acids and bis-imidazole derivatives through collective noncovalent interactions  

NASA Astrophysics Data System (ADS)

Five multicomponent crystals of bis(imidazole) derivatives have been prepared with 5-nitrosalicylic acid, 5-sulfosalicylic acid, and phthalic acid. The five crystalline forms reported are organic salts of which the crystal structures have all been determined by X-ray diffraction. The results presented herein indicate that the strength and directionality of the N sbnd H⋯O, O sbnd H⋯O, and N sbnd H⋯N hydrogen bonds (ionic or neutral) between carboxylic acids and ditopic imidazoles are sufficient to bring about the formation of binary organic salts. All supramolecular architectures of the organic salts 1- 5 involve extensive O sbnd H⋯O, and N sbnd H⋯O hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. These noncovalent interactions combined, all the complexes displayed 3D framework structure.

Jin, Shouwen; Guo, Jianzhong; Liu, Li; Wang, Daqi

2011-10-01

146

Testosterone and brain-derived neurotrophic factor interactions in the avian song control system.  

PubMed

Interaction between steroid sex hormones and brain-derived neurotrophic factor (BDNF) is a common feature of vertebrate brain organization. The avian song control system provides an excellent model for studying such interactions in neural circuits that regulate song, a learned sensorimotor behavior that is often sexually dimorphic and restricted to reproductive contexts. Testosterone (T) and its steroid metabolites interact with BDNF during development of the song system and in adult plasticity, including the addition of newborn neurons to the pallial nucleus HVC and seasonal changes in structure and function of these circuits. T and BDNF interact locally within HVC to influence cell proliferation and survival. This interaction may also occur transsynpatically; T increases the synthesis of BDNF in HVC, and BDNF protein is then released on to postsynaptic cells in the robust nucleus of the arcopallium (RA) where it has trophic effects. The interaction between sex steroids and BDNF is an example of molecular exploitation, with the evolutionarily ancient steroid-receptor complex having been captured by the more recently evolved BDNF. The functional linkage of sex steroids to BDNF may be of adaptive value in regulating the trophic effects of the neurotrophin in sexually dimorphic and reproductively relevant contexts. PMID:23123886

Brenowitz, E A

2013-06-01

147

Effects of the Stellar Component on Derived Physical Parameters of Galactic H II Regions  

NASA Astrophysics Data System (ADS)

We present results of long-slit spatially integrated (~ 7 arcmin2) spectroscopy (3600 - 10200 Å in the central regions of Carina, M8 and M20. We obtained two types of spectra: neb \\ (pure nebular) and all \\ (nebular plus stellar). The stellar effect increases along the Balmer series, with neb/all \\ ~ 1.20 at Hdelta, but could be much stronger (~ 1.7) for weaker lines beyond H8. The resulting neb \\ dereddened spectra give slightly higher electron temperatures which yield (O/H) smaller (~ 0.10-0.30 dex), (N/H) higher (~ 0.05-0.10 dex), (Ne/H) smaller (~ 0.25-0.40 dex), and (Ar/H) smaller (~ 0.15-0.30 dex), with respect to the all \\ case. Although these differences are roughly within the uncertainties, they could be important in deriving accurate chemical compositions in extragalactic nebula where the stars are not resolved.

Robledo-Rella, V.

2000-05-01

148

Low-energy parameters of neutron-neutron interaction in the effective-range approximation  

SciTech Connect

The effect of the mass difference between the charged and neutral pions on the low-energy parameters of nucleon-nucleon interaction in the {sup 1}S{sub 0} state is studied in the effective-range approximation. On the basis of experimental values of the singlet parameters of neutron-proton scattering and the experimental value of the virtual-state energy for the neutron-neutron systemin the {sup 1}S{sub 0} state, the following values were obtained for the neutron-neutron scattering length and effective range: a{sub nn} = -16.59(117) fm and r{sub nn} = 2.83(11) fm. The calculated values agree well with present-day experimental results.

Babenko, V. A.; Petrov, N. M. [National Academy of Sciences of Ukraine, Bogolyubov Institute for Theoretical Physics (Ukraine)

2013-06-15

149

Comprehensive Reference Ranges for Hematology and Clinical Chemistry Laboratory Parameters Derived from Normal Nigerian Adults  

PubMed Central

Background Interpretation of laboratory test results with appropriate diagnostic accuracy requires reference or cutoff values. This study is a comprehensive determination of reference values for hematology and clinical chemistry in apparently healthy voluntary non-remunerated blood donors and pregnant women. Methods and findings Consented clients were clinically screened and counseled before testing for HIV, Hepatitis B, Hepatitis C and Syphilis. Standard national blood donors’ questionnaire was administered to consented blood donors. Blood from qualified volunteers was used for measurement of complete hematology and chemistry parameters. Blood samples were analyzed from a total of 383 participants, 124 (32.4%) males, 125 (32.6%) non-pregnant females and 134 pregnant females (35.2%) with a mean age of 31 years. Our results showed that the red blood cells count (RBC), Hemoglobin (HB) and Hematocrit (HCT) had significant gender difference (p?=?0.000) but not for total white blood count (p>0.05) which was only significantly higher in pregnant verses non-pregnant women (p?=?0.000). Hemoglobin and Hematocrit values were lower in pregnancy (P?=?0.000). Platelets were significantly higher in females than men (p?=?0.001) but lower in pregnant women (p?=?0.001) with marked difference in gestational period. For clinical chemistry parameters, there was no significant difference for sodium, potassium and chloride (p>0.05) but gender difference exists for Bicarbonate (HCO3), Urea nitrogen, Creatinine as well as the lipids (p<0.05). Total bilirubin was significantly higher in males than females (p?=?0.000). Significant differences exist for all chemistry parameters between pregnant and non-pregnant women in this study (p<0.05), except Amylase and total cholesterol (p>0.05). Conclusions Hematological and Clinical Chemistry reference ranges established in this study showed significant gender differences. Pregnant women also differed from non-pregnant females and during pregnancy. This is the first of such comprehensive study to establish reference values among adult Nigerians and difference observed underscore the need to establish reference values for different populations. PMID:24832127

Miri-Dashe, Timzing; Osawe, Sophia; Tokdung, Monday; Daniel, Nenbammun; Choji, Rahila Pam; Mamman, Ille; Deme, Kurt; Damulak, Dapus; Abimiku, Alash'le

2014-01-01

150

Derivate  

NSDL National Science Digital Library

In this activity, students input functions in order to calculate the derivative and tangent line of that function. This activity allows students to explore tangent lines of various functions. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

151

Structural evolution in Pt isotopes with the interacting boson model Hamiltonian derived from the Gogny energy density functional  

SciTech Connect

Spectroscopic calculations are carried out for the description of the shape/phase transition in Pt nuclei in terms of the interacting boson model (IBM) Hamiltonian derived from (constrained) Hartree-Fock-Bogoliubov (HFB) calculations with the finite range and density-dependent Gogny-D1S energy density functional. Assuming that the many-nucleon driven dynamics of nuclear surface deformation can be simulated by effective bosonic degrees of freedom, the Gogny-D1S potential energy surface (PES) with quadrupole degrees of freedom is mapped onto the corresponding PES of the IBM. By using this mapping procedure, the parameters of the IBM Hamiltonian, relevant to the low-lying quadrupole collective states, are derived as functions of the number of valence nucleons. Merits of both Gogny-HFB and IBM approaches are utilized so that the spectra and the wave functions in the laboratory system are calculated precisely. The experimental low-lying spectra of both ground-state and sideband levels are well reproduced. From the systematics of the calculated spectra and the reduced E2 transition probabilities B(E2), the prolate-to-oblate shape/phase transition is shown to take place quite smoothly as a function of neutron number N in the considered Pt isotopic chain, for which the {gamma} softness plays an essential role. All of these spectroscopic observables behave consistently with the relevant PES and the derived parameters of the IBM Hamiltonian as functions of N. Spectroscopic predictions are also made for those nuclei that do not have enough experimental E2 data.

Nomura, K. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Otsuka, T. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Rodriguez-Guzman, R.; Sarriguren, P. [Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain); Robledo, L. M. [Departamento de Fisica Teorica, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)

2011-01-15

152

Lunar tidal acceleration obtained from satellite-derived ocean tide parameters  

NASA Technical Reports Server (NTRS)

One hundred sets of mean elements of GEOS-3 computed at 2-day intervals yielded observation equations for the M sub 2 ocean tide from the long periodic variations of the inclination and node of the orbit. The 2nd degree Love number was given the value k sub 2 = 0.30 and the solid tide phase angle was taken to be zero. Combining obtained equations with results for the satellite 1967-92A gives the M sub 2 ocean tide parameter values. Under the same assumption of zero solid tide phase lag, the lunar tidal acceleration was found mostly due to the C sub 22 term in the expansion of the M sub 2 tide with additional small contributions from the 0 sub 1 and N sub 2 tides. Using Lambeck's (1975) estimates for the latter, the obtained acceleration in lunar longitudal in excellent agreement with the most recent determinations from ancient and modern astronomical data.

Goad, C. C.; Douglas, B. C.

1978-01-01

153

Accuracy of Geophysical Parameters Derived from AIRS/AMSU as a Function of Fractional Cloud Cover  

NASA Technical Reports Server (NTRS)

AIRS was launched on EOS Aqua on May 4,2002, together with AMSU A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of lK, and layer precipitable water with an rms error of 20 percent, in cases with up to 80 percent effective cloud cover. The basic theory used to analyze Atmospheric InfraRed Sounder/Advanced Microwave Sounding Unit/Humidity Sounder Brazil (AIRS/AMSU/HSB) data in the presence of clouds, called the at-launch algorithm, was described previously. Pre-launch simulation studies using this algorithm indicated that these results should be achievable. Some modifications have been made to the at-launch retrieval algorithm as described in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and validated as a function of retrieved fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small and the RMS accuracy of lower tropospheric temperature retrieved with 80 percent cloud cover is about 0.5 K poorer than for clear cases. HSB failed in February 2003, and consequently HSB channel radiances are not used in the results shown in this paper. The AIRS/AMSU retrieval algorithm described in this paper, called Version 4, become operational at the Goddard DAAC (Distributed Active Archive Center) in April 2003 and is being used to analyze near-real time AIRS/AMSU data. Historical AIRS/AMSU data, going backwards from March 2005 through September 2002, is also being analyzed by the DAAC using the Version 4 algorithm.

Susskind, Joel; Barnet, Chris; Blaisdell, John; Iredell, Lena; Keita, Fricky; Kouvaris, Lou; Molnar, Gyula; Chahine, Moustafa

2006-01-01

154

Accuracy of Geophysical Parameters Derived from AIRS/AMSU as a Function of Fractional Cloud Cover  

NASA Technical Reports Server (NTRS)

AIRS was launched on EOS Aqua on May 4,2002, together with AMSU A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of 1K, and layer precipitable water with an rms error of 20%, in cases with up to 80% effective cloud cover. The basic theory used to analyze AIRS/AMSU/HSB data in the presence of clouds, called the at-launch algorithm, was described previously. Pre-launch simulation studies using this algorithm indicated that these results should be achievable. Some modifications have been made to the at-launch retrieval algorithm as described in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and validated as a function of retrieved fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small. HSB failed in February 2005, and consequently HSB channel radiances are not used in the results shown in this paper. The AIRS/AMSU retrieval algorithm described in this paper, called Version 4, become operational at the Goddard DAAC in April 2005 and is being used to analyze near-real time AIRS/AMSU data. Historical AIRS/AMSU data, going backwards from March 2005 through September 2002, is also being analyzed by the DAAC using the Version 4 algorithm.

Susskind, Joel; Barnet, Chris; Blaisdell, John; Iredell, Lena; Keita, Fricky; Kouvaris, Lou; Molnar, Gyula; Chahine, Moustafa

2005-01-01

155

Physical parameters of the near-surface of Mars derived from SHARAD radar reflectivity: Statistical approach  

NASA Astrophysics Data System (ADS)

Onboard sounding radars are relatively new instruments in planetary exploration. This method is ground penetrating and then well suited to the search for buried water ice on Mars. Their capacity to resolve glacial structures down to kilometers depth has already provided precious informations related to Martian glaciers. Sounding radars are also relevant tools to determine the physical parameters of the near-surface from reflectivity measurements. Whereas common observation instruments do not exceed few millimeters, radar reflectivity probes the first de-cameters of the surface (depending on the bandwidth). Because radar reflectivity contains information on both the surface geometry and geologic composition, a main issue is to apply an efficient method to separate those components. The SHAllow RADar (SHARAD/ASI) is an instrument onboard the NASA's Mars Reconnais-sance Orbiter (MRO). The routine science observations that started in November 2006 is still ongoing. SHARAD provides remote sensing observations of most of the Martian surface at a 20 MHz frequency (10 MHz bandwidth). The along-track foot print range is between 0.3 and 1 km, while the typical footprint radius (Fresnel zone) is 1.5 km. SHARAD reflectivity depends on the first 5-10 meters of the surface, according to the dielectric constant of the sounded material. In terrestrial SAR (synthetic aperture radar) imagery, numerous statistical methods were exten-sively studied because of their abilities to classify remote terrains. Here we present applications of such methods based on SAR statistics to extract the physical parameters embedded in the SHARAD reflected signal of the near-surface. Preliminary results are reported over different key regions of Mars -especially glacial and periglacial units -in order to illustrate the limits and the possibilities of this approach.

Grima, Cyril; Kofman, Wlodek; Herique, Alain; Seu, Roberto

156

Modeling dispersion of dry powders for inhalation. The concepts of total fines, cohesive energy and interaction parameters.  

PubMed

A range of carrier based dry powder formulations consisting of micronized drug, carrier lactose and, in some formulations, lactose fines were produced and tested for dispersibility, i.e. fine particle fraction (FPF). Two different drugs were used, budesonide (BUD) and beclomethasone dipropionate (BDP). A model based on the total amount of fines (TF) and the cohesive energy (CE) of the formulation is proposed, where TF is the sum of added drug, lactose fines and the fines inherent to the carrier. The expression for CE is derived from regular solutions theory and allows calculation of interparticle interaction parameters. The model was able to describe experimental data well, such as the decrease in FPF when the proportion of drug is increased at a constant TF level and the non-linear effects seen when a cohesive drug is added to carrier. BDP and BUD were found to be 5.3 times and 1.8 times more cohesive than lactose fines respectively. The model hence provides a link between the macroscopic behavior of a dry powder formulation and the interaction between the different species at the particulate level. PMID:22349053

Thalberg, Kyrre; Berg, Elna; Fransson, Magnus

2012-05-10

157

Fundamental thermal emission parameters of main-belt asteroids derived from ISO  

NASA Astrophysics Data System (ADS)

In support for the ISO Mission it has been necessary to establish a set of asteroids as photometric standards for the photometric calibration of the instruments ( te{Mueller:98a}). The new standards are described as rotating ellipsoids. Illumination geometry, heat transfer due to non-zero thermal inertia and surface structure/porosity are taken into account. The characteristic properties of this new thermophysical model (TPM) can be found in te*{Lagerros:96a,Lagerros:97a,Lagerros:97b}. Here we apply the TPM to a set of ISO observations on (1) Ceres to derive its thermophysical properties. We determine the thermal inertia, the beaming function, caused by surface roughness and porosity, and the wavelength dependent emissivity. Since we are able to model the full thermal emission over the wavelengths range from 5 to 200 ?m, we believe that our findings represent fundamental thermal emission properties not only of (1) Ceres, but also of other Main-Belt asteroids.

Muller, T. G.; Lagerros, J. S. V.; Burgdorf, M.; Lim, T.; Morris, P. W.; Salama, A.; Schulz, B.; Vandenbussche, B.

1999-03-01

158

Theoretical and experimental local reactivity parameters of 3-substituted coumarin derivatives.  

PubMed

Local reactivity descriptors, such as atomic charges, atomic electrostatic potential and atomic Fukui indices were computed for a series of 3-substituted coumarin (2-oxo-2H-1-benzopyran) derivatives, using density functional theory (DFT) and Möller-Plesset methods (MP2). The variation of those properties as a function of the substituents was compared with the variation of the measured XPS binding energies. The atomic electrostatic potentials and XPS binding energies serves as indicators of the electrophilicity of a given center within a molecule, while the atomic Fukui indices describe its degree of electronic localization, known as atomic softness. The correlation between those theoretical and experimental properties allowed us to follow the effect of electron withdrawing substituents on the electrophilicity of a given atomic center. The Fukui indices provided additional information about the softening/hardening of the center of interest due to presence of different substituents to the coumarin system. On the basis of these analysis, the 1,2-addition would be favored for 3-acetyl, 3-phosphono, and 7-diethylamino substituents, while 3-carboxyl, 3-ethoxycarbonyl, and 3-nitro substituent would favor 1,4-addition. The substituted coumarins would preferably react with soft nucleophiles at position 2 and with hard nucleophiles at position 4. PMID:25347691

Petkova, Nevena I; Nikolova, Rositca D; Kostov, Krassimir L; Mineva, Tzonka; Vayssilov, Georgi N

2014-11-20

159

A quantitative uncertainty assessment of eruptive parameters derived from tephra deposits: the example of two large eruptions of Cotopaxi volcano, Ecuador  

Microsoft Academic Search

Physical parameters of explosive eruptions are typically derived from tephra deposits. However, the characterization of a\\u000a given eruption relies strongly on the quality of the dataset used, the strategy chosen to obtain and process field data and\\u000a the particular model considered to derive eruptive parameters. As a result, eruptive parameters are typically affected by\\u000a a certain level of uncertainty and

Sébastien Biass; Costanza Bonadonna

2011-01-01

160

Composite genome map and recombination parameters derived from three archetypal lineages of Toxoplasma gondii  

PubMed Central

Toxoplasma gondii is a highly successful protozoan parasite in the phylum Apicomplexa, which contains numerous animal and human pathogens. T.gondii is amenable to cellular, biochemical, molecular and genetic studies, making it a model for the biology of this important group of parasites. To facilitate forward genetic analysis, we have developed a high-resolution genetic linkage map for T.gondii. The genetic map was used to assemble the scaffolds from a 10X shotgun whole genome sequence, thus defining 14 chromosomes with markers spaced at ?300 kb intervals across the genome. Fourteen chromosomes were identified comprising a total genetic size of ?592 cM and an average map unit of ?104 kb/cM. Analysis of the genetic parameters in T.gondii revealed a high frequency of closely adjacent, apparent double crossover events that may represent gene conversions. In addition, we detected large regions of genetic homogeneity among the archetypal clonal lineages, reflecting the relatively few genetic outbreeding events that have occurred since their recent origin. Despite these unusual features, linkage analysis proved to be effective in mapping the loci determining several drug resistances. The resulting genome map provides a framework for analysis of complex traits such as virulence and transmission, and for comparative population genetic studies. PMID:15911631

Khan, Asis; Taylor, Sonya; Su, Chunlei; Mackey, Aaron J.; Boyle, Jon; Cole, Robert; Glover, Darius; Tang, Keliang; Paulsen, Ian T.; Berriman, Matt; Boothroyd, John C.; Pfefferkorn, Elmer R.; Dubey, J. P.; Ajioka, James W.; Roos, David S.; Wootton, John C.; Sibley, L. David

2005-01-01

161

Studies on the interaction mechanism of aminopyrene derivatives with human tumor-related DNA.  

PubMed

Polycyclic aromatic hydrocarbons derivatives (PAHs) have been confirmed to be carcinogenic, teratogenic and mutagenic, and have the potential to cause human malignant diseases. In this work, interactions of two selected amino-PAHs (aminopyrene derivatives) and human tumor-related DNA were evaluated using spectroscopic and polyacrylamide gel electrophoresis (PAGE) methods. Spectroscopic results demonstrated that there were remarkable interactions between PAHs and the targeted DNA with the order of the binding ability as 1-AP>1-PBA. The binding constants of 1-AP with the targeted DNA were at the level of about 10(6) L/mol, while that of 1-PBA only to about 10(3) L/mol. 1-AP with a short side-chain acted mainly as an intercalator, and its interactions with DNA were strengthened with electrostatic forces. As for 1-PBA with a flexible long side-chain, the intercalation mode was dominated with an auxiliary role of Van der Wals forces and hydrogen bonds. Besides, the binding abilities of amino-PAHs to p53 DNA seemed stronger than that for C-myc DNA. PAGE results showed that the binding of amino-PAHs could further change the conformation of DNA sequences from the duplex to the antiparallel G-quadruplex. PMID:23608671

Li, Li; Lu, Jia; Zhou, Wenshu; Li, Huihui; Yang, Xiaodi

2013-06-01

162

Ab initio DFT study of bisphosphonate derivatives as a drug for inhibition of cancer: NMR and NQR parameters.  

PubMed

DFT computations were carried out to characterize the (17)Oand (2)H electric field gradient, EFG, in various bisphosphonate derivatives. The computations were performed at the B3LYP level with 6-311++G (d,P) standard basis set. Calculated EFG tensors were used to determine the (17)O and (2)H nuclear quadrupole coupling constant, ? and asymmetry parameter, ?. For better understanding of the bonding and electronic structure of bisphosphonates, isotropic and anisotropic NMR chemical shieldings were calculated for the (13)C, (17)O and (31)P nuclei using GIAO method for the optimized structure of intermediate bisphosphonates at B3LYP level of theory using 6-311++G (d, p) basis set. The results showed that various substituents have a strong effect on the nuclear quadrupole resonance (NQR) parameters (?, ?) of (17)O in contrast with (2)H NQR parameters. The NMR and NQR parameters were studied in order to find the correlation between electronic structure and the activity of the desired bisphosphonates. In addition, the effect of substitutions on the bisphosphonates polarity was investigated. Molecular polarity was determined via the DFT calculated dipole moment vectors and the results showed that substitution of bromine atom on the ring would increase the activity of bisphosphonates. PMID:21633790

Aghabozorg, Hussein; Sohrabi, Beheshteh; Mashkouri, Sara; Aghabozorg, Hamid Reza

2012-03-01

163

Electronic polarizability and interaction parameter of gadolinium tungsten borate glasses with high WO3 content  

NASA Astrophysics Data System (ADS)

Glasses with the compositions of 25Gd2O3-xWO3-(75-x)B2O3 with x=25-65 were prepared by using a conventional melt quenching method, and their electronic polarizabilities, optical basicities ?(no), and interaction parameters A(no) were estimated from density and refractive index measurements in order to clarify the feature of electronic polarizability and bonding states in the glasses with high WO3 contents. The optical basicity of the glasses increases monotonously with the substitution of WO3 for B2O3, and contrary the interaction parameter decreases monotonously with increasing WO3 content. A good linear correlation was observed between ?(no) and A(no) and between the glass transition temperature and A(no). It was proposed that Gd2O3 oxide belongs to the category of basic oxide with a value of A(no)=0.044 Å-3 as similar to WO3. The relationship between the glass formation and electronic polarizability in the glasses was discussed, and it was proposed that the glasses with high WO3 and Gd2O3 contents would be a floppy network system consisting of mainly basic oxides.

Taki, Yukina; Shinozaki, Kenji; Honma, Tsuyoshi; Dimitrov, Vesselin; Komatsu, Takayuki

2014-12-01

164

New Skyrme interaction parameters for a unified description of the nuclear properties  

NASA Astrophysics Data System (ADS)

The nucleon microscopic optical potential is obtained by calculating the mass operator of the one-particle Green function with an effective Skyrme interaction. The real and imaginary part potentials for finite nuclei are given by applying a local density approximation as usual, while the spin-orbit potential is further amended by using the Skyrme-Hartree-Fock approach and relativistic mean field results. The new variants of Skyrme interaction parameters are found by simultaneously fitting the characteristics of nuclear matter, the binding energy, charge radius and single-particle energy levels of double closed shell nuclei, the neutron induced reaction cross sections and polarization data. These data include the total cross sections, nonelastic sections, elastic scattering angular distributions and analyzing powers for the target mass range 24 ? A ? 209 with incident neutron energies below 100 MeV. Further, the Landau parameters are considered to describe the properties of an excited state. The obtained variants of Skyrme forces are used to predict the neutron-actinide reactions with incident energies below 100 MeV. It is found that the calculations can give a satisfactory description of the experimental data. Analogous calculations by the new Skyrme forces are performed to predict the proton induced reactions, which also yield reasonable results.

Xu, Yongli; Guo, Hairui; Han, Yinlu; Shen, Qingbiao

2014-01-01

165

Determination of orbital parameters of interacting galaxies using a genetic algorithm. Description of the method and application to artificial data  

E-print Network

A method for determining the orbital parameters of interacting pairs of galaxies is presented and evaluated using artificial data. The method consists of a genetic algorithm which can search efficiently through the very large space of possible orbits. It is found that, in most cases, orbital parameters close to the actual orbital parameters of the pair can be found. The method does not require information about the velocity field of the interacting system, and is able to cope with noisy data. The inner regions of the galaxies, which are difficult to model, can be neglected, and the orbital parameters can be determined using the remaining information.

M. Wahde

1997-10-24

166

Derivation of Spatial Parameters to Estimate Mass Delivery of Pesticides to Ground Water in Morgan Creek, Maryland  

NASA Astrophysics Data System (ADS)

Water and solutes in the unsaturated zone are being intensively monitored at multiple sites in Morgan Creek, Maryland as part of the U.S. Geological Survey?s National Water- Quality Assessment (NAWQA) program. The observations are being used to calibrate simple and complex one-dimensional models that simulate the movement of water and the transformation pesticides in the unsaturated zone beneath the monitored sites. However, the monitored sites are limited in their representation of pesticide fluxes through the larger watershed encompassing the sites. This paper describes how ensembles of spatially distributed model parameters were derived to predict mass delivery of pesticides to the ground water in the larger watershed of Morgan Creek. Model parameters describing pesticide solubility, dispersion, sorbtivity, and transformation rates were calibrated to match concentrations of pesticides and metabolites observed in lysimeter samples installed at the intensive monitoring sites. The parameters describing the pesticide properties were then held fixed in a suite of models built to represent the variety of land use, soils, and unsaturated-zone thicknesses found in the Morgan Creek watershed. Land-use data were compiled from the Geographic Information Retrieval Analysis System (GIRAS), the National Land Cover Dataset (NLCD), and field surveys. Soil-erodibility and bulk-density information was obtained from the State Survey Geographic (STATSGO) database, whereas descriptions of soil texture, organic material, permeability, and available water-capacity values were obtained from the more detailed Soil Survey Geographic (SSURGO) database. Unsaturated-thickness information was created from the difference between a 30-meter resolution grid of head values, created using the results of a steady-state modular three-dimensional ground-water flow model (MODFLOW), and a 3-meter resolution digital elevation model (DEM, resampled to 30-meter), derived from Light Detection and Ranging (LIDAR). A point coverage of 100-meter spacing was overlaid onto the resulting maps of land use, soils, and unsaturated-zone thickness to identify the characteristics of the watershed surrounding the intensive monitoring sites. The approximately 3,300 sampled points were then subjected to a cluster analysis to identify regions with similar characteristics and to estimate the statistical distribution of specific model parameters within each region. Where nominal values were encountered, a noise model was added to provide a range in expected values. The mean and variance for each parameter in a cluster were then used to define the parameter space for input to models simulating the unsaturated-zone processes within each cluster. Finally, model predictions and confidence intervals were weighted by the area of each cluster to arrive at estimates of fluxes of water and sediment in the larger watershed.

Wieczorek, M. E.; Webb, R. M.

2006-05-01

167

3D visualization of derived hydrophysical parameters in Lakes and Inland Seas. New approach to applied hydrodynamics.  

NASA Astrophysics Data System (ADS)

Based on numerical simulation results, derived parameters computed from output variables and represented in 3D are used to have a clearer approach to the hydrodynamics of real systems. More precisely, a 3D dynamic visualization of the Shannon entropy of the velocity direction field is shown to illustrate the horizontal mixing related to the flow dynamics in the case of the Aral and Black sea applications. Previous to that some video test cases are presented in order to have a close view of what is highlighted with this approach. Complementarily, the physical meaning of the Shannon entropy of velocity directions is discussed in comparison with more standard derived variables such as the Obuko-Weiss parameter. The Shannon entropy of other scalar fields is also represented and used for the discussion. The utility of these tools for science as well as for management and more popular applications is discussed. Acknowledgments: This research was developed within the framework of the CLIMSEAS project FP7-IRSES-2009 (ref. 247512).

Barcaru, A.; Roget, E.; Sbert, M.; Zavialov, P.; Korontenko, K.; Feixas, M.

2012-04-01

168

About intermolecular interactions in binary and ternary solutions of some azo-benzene derivatives.  

PubMed

The nature and strength of the intermolecular interactions in the solutions of three azo-benzene derivatives (ADi, i=1, 2, 3) were established by solvatochromic effects in solvents with different electric permittivities, refractive indices and Kamlet-Taft constants. A quantum mechanical analysis corroborated with spectral data offered information about the excited state dipole moments and polarizabilities of the studied compounds. The separation of the supply of universal and specific interactions to the total spectral shift was made based on the regression coefficients from the equations describing the solvatochromic effect. Supplementary information about the composition of the first solvation shell and the energy in the solute-solvent molecular pairs were obtained analyzing the ternary solutions of ADi, i=1, 2, 3 compounds in solvent mixture Methanol (M)+n-Hexane (H). PMID:25168003

Ivan, Liliana Mihaela; Closca, Valentina; Burlea, Marin; Rusu, Elena; Airinei, Anton; Dorohoi, Dana Ortansa

2015-02-01

169

Characterization of lesion formation and bubble activities during high-intensity focused ultrasound ablation using temperature-derived parameters  

NASA Astrophysics Data System (ADS)

Successful high-intensity focused ultrasound (HIFU) thermal tissue ablation relies on accurate information of the tissue temperature and tissue status. Often temperature measurements are used to predict and monitor the ablation process. In this study, we conducted HIFU ablation experiments with ex vivo porcine myocardium tissue specimens to identify changes in temperature associated with tissue coagulation and bubble/cavity formation. Using infrared (IR) thermography and synchronized bright-field imaging with HIFU applied near the tissue surface, parameters derived from the spatiotemporal evolution of temperature were correlated with HIFU-induced lesion formation and overheating, of which the latter typically results in cavity generation and/or tissue dehydration. Emissivity of porcine myocardium was first measured to be 0.857 ± 0.006 (n = 3). HIFU outcomes were classified into non-ablative, normal lesion, and overheated lesion. A marked increase in the rate of temperature change during HIFU application was observed with lesion formation. A criterion using the maximum normalized second time derivative of temperature change provided 99.1% accuracy for lesion identification with a 0.05 s-1 threshold. Asymmetric temperature distribution on the tissue surface was observed to correlate with overheating and/or bubble generation. A criterion using the maximum displacement of the spatial location of the peak temperature provided 90.9% accuracy to identify overheated lesion with a 0.16 mm threshold. Spatiotemporal evolution of temperature obtained using IR imaging allowed determination of the critical cumulative equivalent minutes at 43 °C (CEM43) for lesion formation to be 170 min. Similar temperature characteristics indicative of lesion formation and overheating were identified for subsurface HIFU ablation. These results suggest that parameters derived from temperature changes during HIFU application are associated with irreversible changes in tissue and may provide useful information for monitoring HIFU treatment.

Hsiao, Yi-Sing; Kumon, Ronald E.; Deng, Cheri X.

2013-09-01

170

Soil erosion modelled with USLE and PESERA using QuickBird derived vegetation parameters in an alpine catchment  

NASA Astrophysics Data System (ADS)

The focus of soil erosion research in the Alps has been in two categories: (i) on-site measurements, which are rather small scale point measurements on selected plots often constrained to irrigation experiments or (ii) off-site quantification of sediment delivery at the outlet of the catchment. Results of both categories pointed towards the importance of an intact vegetation cover to prevent soil loss. With the recent availability of high-resolution satellites such as IKONOS and QuickBird options for detecting and monitoring vegetation parameters in heterogeneous terrain have increased. The aim of this study is to evaluate the usefulness of QuickBird derived vegetation parameters in soil erosion models for alpine sites by comparison to Cesium-137 (Cs-137) derived soil erosion estimates. The study site (67 km 2) is located in the Central Swiss Alps (Urseren Valley) and is characterised by scarce forest cover and strong anthropogenic influences due to grassland farming for centuries. A fractional vegetation cover (FVC) map for grassland and detailed land-cover maps are available from linear spectral unmixing and supervised classification of QuickBird imagery. The maps were introduced to the Pan-European Soil Erosion Risk Assessment (PESERA) model as well as to the Universal Soil Loss Equation (USLE). Regarding the latter model, the FVC was indirectly incorporated by adapting the C factor. Both models show an increase in absolute soil erosion values when FVC is considered. In contrast to USLE and the Cs-137 soil erosion rates, PESERA estimates are low. For the USLE model also the spatial patterns improved and showed "hotspots" of high erosion of up to 16 t ha -1 a -1. In conclusion field measurements of Cs-137 confirmed the improvement of soil erosion estimates using the satellite-derived vegetation data.

Meusburger, K.; Konz, N.; Schaub, M.; Alewell, C.

2010-06-01

171

Characterization of Lesion Formation and Bubble Activities during High Intensity Focused Ultrasound Ablation using Temperature-Derived Parameters  

PubMed Central

Successful high-intensity focused ultrasound (HIFU) thermal tissue ablation relies on accurate information of the tissue temperature and tissue status. Often temperature measurements are used to predict and monitor the ablation process. In this study, we conducted HIFU ablation experiments with ex vivo porcine myocardium tissue specimens to identify changes in temperature associated with tissue coagulation and bubble/cavity formation. Using infrared (IR) thermography and synchronized bright-field imaging with HIFU applied near the tissue surface, parameters derived from the spatiotemporal evolution of temperature were correlated with HIFU-induced lesion formation and overheating, of which the latter typically results in cavity generation and/or tissue dehydration. Emissivity of porcine myocardium was first measured to be 0.857 ± 0.006 (n = 3). HIFU outcomes were classified into non-ablative, normal lesion, and overheated lesion. A marked increase in the rate of temperature change during HIFU application was observed with lesion formation. A criterion using the maximum normalized second time derivative of temperature change provided 99.1% accuracy for lesion identification with a 0.05 s?1 threshold. Asymmetric temperature distribution on the tissue surface was observed to correlate with overheating and/or bubble generation. A criterion using the maximum displacement of the spatial location of the peak temperature provided 90.9% accuracy to identify overheated lesion with a 0.16 mm threshold. Spatiotemporal evolution of temperature obtained using IR imaging allowed determination of the cumulative equivalent minutes at 43 °C (CEM43) for lesion formation to be 170 min. Similar temperature characteristics indicative of lesion formation and overheating were identified for subsurface HIFU ablation. These results suggest that parameters derived from temperature changes during HIFU application are associated with irreversible changes in tissue and may provide useful information for monitoring HIFU treatment. PMID:23878517

Hsiao, Yi-Sing; Kumon, Ronald E.; Deng, Cheri X.

2013-01-01

172

Interaction between tachyplesin I, an antimicrobial peptide derived from horseshoe crab, and lipopolysaccharide.  

PubMed

Lipopolysaccharide (LPS) is a major constituent of the outer membrane of Gram-negative bacteria and is the very first site of interactions with antimicrobial peptides (AMPs). In order to gain better insight into the interaction between LPS and AMPs, we determined the structure of tachyplesin I (TP I), an antimicrobial peptide derived from horseshoe crab, in its bound state with LPS and proposed the complex structure of TP I and LPS using a docking program. CD and NMR measurements revealed that binding to LPS slightly extends the two ?-strands of TP I and stabilizes the whole structure of TP I. The fluorescence wavelength of an intrinsic tryptophan of TP I and fluorescence quenching in the presence or absence of LPS indicated that a tryptophan residue is incorporated into the hydrophobic environment of LPS. Finally, we succeeded in proposing a structural model for the complex of TP I and LPS by using a docking program. The calculated model structure suggested that the cationic residues of TP I interact with phosphate groups and saccharides of LPS, whereas hydrophobic residues interact with the acyl chains of LPS. PMID:24389234

Kushibiki, Takahiro; Kamiya, Masakatsu; Aizawa, Tomoyasu; Kumaki, Yasuhiro; Kikukawa, Takashi; Mizuguchi, Mineyuki; Demura, Makoto; Kawabata, Shun-ichiro; Kawano, Keiichi

2014-03-01

173

Studies on the interactions of bioactive quinone avarone and its methylamino derivatives with calf thymus DNA.  

PubMed

The interactions of avarone, a quinone from the marine sponge Dysideaavara, and the methylamino derivatives of avarone (2), 3'-(methylamino)avarone (3) and 4'-(methylamino)avarone (4) with calf thymus DNA (CT-DNA) were studied. Agarose gel electrophoreticanalysis showed that binding of the quinones quenched fluorescence of ethidium bromide (EB). The extent of fluorescence quenching of intercalator EB by competitive displacement from EB-CT-DNA system and of groove binder Hoechst 33258 (H) from H-CT-DNA system with the quinones was analyzed by fluorescence spectroscopy. The obtained results demonstrated that the quinones reduced binding of both the intercalator EB and the minor groove binder H, indicating possible degradation of DNA. The substituent on the quinone moiety determined the extent of DNA damaging effect of the quinone, which was the most extensive with 3'-(methylamino)avarone and the least extensive with its regioisomer 4'-(methylamino)avarone. The results were confirmed by the observed hyperchromic effects in UV-visible spectra measured after interactions of the derivatives with CT-DNA. PMID:24080453

Vuj?i?, Miroslava T; Tufegdži?, Sr?an; Novakovi?, Irena; Djikanovi?, Daniela; Gaši?, Miroslav J; Sladi?, Dušan

2013-11-01

174

Dark matter-dark energy interaction for a time-dependent EoS parameter  

NASA Astrophysics Data System (ADS)

In this work we investigate the interaction between dark matter and dark energy for a coupling that obeys the Wang-Meng decaying law, $\\rho_{{\\rm DM}}\\propto (1+z)^{3-\\epsilon}$, and the Barboza-Alcaniz dark energy parametric model, $w=w_0+w'_0z(1+z)/(1+z^2)$. Theoretically, we show that the coupling constant, $\\epsilon$, should satisfy the physical constraint $\\epsilon\\ge0$. We use the most recent data of type Ia supernovae, baryon acoustic oscillations, cosmic microwave background and the Hubble expansion rate function to constrain the free parameters of the model. From a purely observational point of view, we show that is not possible to discard values of the coupling constant in the unphysical region $\\epsilon<0$. We show that the uncoupled case, $\\epsilon=0$, is in better agreement with the data than any of coupled models in the physical region. We also find that all physically acceptable interaction in dark sector lies in the narrow range $0<\\epsilon\\le0.034$ ($95\\%$ CL).

Nunes, Rafael C.; Barboza, Edésio M.

2014-11-01

175

Coulomb interaction parameters in bcc iron: an LDA+DMFT study.  

PubMed

We study the influence of Coulomb interaction parameters on electronic structure and magnetic properties of paramagnetic bcc Fe by means of the local density approximation plus dynamical mean-field theory approach. We consider the local Coulomb interaction in the density-density form as well as in the form with spin rotational invariance approximated by averaging over all directions of the quantization axis. Our results indicate that the magnetic properties of bcc Fe are mainly affected by the Hund's rule coupling J rather than by the Hubbard U. By employing the constrained density functional theory approach in the basis of Wannier functions of spd character, we obtain U = 4 eV and J = 0.9 eV. In spite of the widespread belief that U = 4 eV is too large for bcc Fe, our calculations with the obtained values of U and J result in a satisfactory agreement with the experiment. The correlation effects caused by U are found to be weak even for large U = 6 eV. The agreement between the calculated and experimental Curie temperatures is further improved if J is reduced to 0.8 eV. However, with the decrease of J, the effective local magnetic moment moves further away from the experimental value. PMID:25156797

Belozerov, A S; Anisimov, V I

2014-09-17

176

Experimental parameter estimation of a visuo-vestibular interaction model in humans.  

PubMed

Visuo-vestibular interactions in monkeys can be accurately modelled using the classical Raphan and Cohen's model. This model is composed of direct vestibular and visual contributions to the vestibulo-ocular reflex (VOR) and of a velocity storage. We applied this model to humans and estimated its parameters in a series of experiments: yaw rotations at moderate (60°/s) and high velocities (240°/s), suppression of the VOR by a head-fixed wide-field visual stimulus, and optokinetic stimulation with measurements of optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN). We found the velocity storage time constant to be 13 s, which decreased to 8 s during visual suppression. OKAN initial velocity was 12% of the OKN stimulus velocity. The gain of the direct visual pathway was 0.75 during both visual suppression and OKN; however, the visual input to the velocity storage was higher during visual suppression than during OKN. We could not estimate the time constant of the semicircular canals accurately. Finally, we inferred from high-velocity rotations that the velocity storage saturates around 20-30°/s. Our results indicate that the dynamics of visuo-vestibular interactions in humans is similar as in monkeys. The central integration of visual cues, however, is weaker in humans. PMID:22101296

Laurens, Jean; Valko, Yulia; Straumann, Dominik

2011-01-01

177

Coulomb interaction parameters in bcc iron: an LDA+DMFT study  

NASA Astrophysics Data System (ADS)

We study the influence of Coulomb interaction parameters on electronic structure and magnetic properties of paramagnetic bcc Fe by means of the local density approximation plus dynamical mean-field theory approach. We consider the local Coulomb interaction in the density-density form as well as in the form with spin rotational invariance approximated by averaging over all directions of the quantization axis. Our results indicate that the magnetic properties of bcc Fe are mainly affected by the Hund's rule coupling J rather than by the Hubbard U. By employing the constrained density functional theory approach in the basis of Wannier functions of spd character, we obtain U = 4 eV and J = 0.9 eV. In spite of the widespread belief that U = 4 eV is too large for bcc Fe, our calculations with the obtained values of U and J result in a satisfactory agreement with the experiment. The correlation effects caused by U are found to be weak even for large U = 6 eV. The agreement between the calculated and experimental Curie temperatures is further improved if J is reduced to 0.8 eV. However, with the decrease of J, the effective local magnetic moment moves further away from the experimental value.

Belozerov, A. S.; Anisimov, V. I.

2014-09-01

178

New natural shapes of non-Gaussianity from high-derivative interactions and their optimal limits from WMAP 9-year data  

NASA Astrophysics Data System (ADS)

Given the fantastic experimental effort, it is important to thoroughly explore the signature space of inflationary models. The fact that higher derivative operators do not renormalize lower derivative ones allows us to find a large class of technically natural single-clock inflationary models where, in the context of the Effective Field Theory of Inflation, the leading interactions have many derivatives. We systematically explore the 3-point function induced by these models and their overlap with the standard equilateral and orthogonal templates. We find that in order to satisfactorily cover the signature space of these models, two new additional templates need to be included. We then perform the optimal analysis of the WMAP 9-year data for the resulting four templates, finding that the overall significance of a non-zero signal is between 2–2.5?, depending on the choice of parameter space, partially driven by the preference for nonzero fNLorth in WMAP9.

Behbahani, Siavosh R.; Mirbabayi, Mehrdad; Senatore, Leonardo; Smith, Kendrick M.

2014-11-01

179

Automated procedure to derive fundamental parameters of B and A stars: Application to the young cluster NGC 3293  

E-print Network

This work describes a procedure to derive several fundamental parameters such as the effective temperature, surface gravity, equatorial rotational velocity and microturbulent velocity. In this work, we have written a numerical procedure in Python which finds the best fit between a grid of synthetic spectra and the observed spectra by minimizing a standard chi-square. LTE model atmospheres were calculated using the ATLAS9 code and were used as inputs to the spectrum synthesis code SYNSPEC48 in order to compute a large grid of synthetic Balmer line profiles. This new procedure has been applied to a large number of new observations (GIRAFFE spectra) of B and A stars members of the young open cluster NGC3293. These observations are part of the GAIA ESO Survey. Takeda's procedure was also used to derive rotational velocities and microturbulent velocities. The results have been compared to previous determinations by other authors and are found to agree with them. As a first result, we concluded that using this proc...

Aydi, E; Monier, R; Royer, F; Lobel, A; Blomme, R

2014-01-01

180

Comparison of biokinetics and biliary imaging parameters of four /sup 99m/Tc iminodiacetic acid derivatives in normal subjects  

SciTech Connect

The biokinetics (blood clearance, urinary excretion, hepatic peak time, uptake, and excretion t-1/2) and the imaging parameters (the time of appearance of the common bile duct, gallbladder, and duodenum) were determined in 34 normal subjects using /sup 99m/Tc diethyl (EIDA), /sup 99m/Tc dimethyl (HIDA), /sup 99m/Tc paraisopropyl (PIPIDA), and /sup 99m/Tc parabutyl (PBIDA) iminodiacetic acid derivatives. The blood and hepatic clearance of the four agents were significantly different (P less than 0.05) from each other. The 24-hour urinary excretion of PBIDA was significantly lower (P less than 0.05) than the urinary excretion of the other three agents. There was no difference among the four agents in the time of appearance of the gallbladder and duodenum. The time of appearance of the common bile duct was significantly delayed with PBIDA. The maximum intensity of the common bile duct usually occurred between 20 to 40 minutes with all four agents. However, gallbladder intensity continued to increase up to 3 hours. It is concluded that in the presence of normal liver function, all four /sup 99m/Tc IDA agents show definite differences in biokinetics but these differences do not have a major effect on biliary imaging parameters. If imaging alone is the primary goal, the selection of any one of the four agents will meet the clinican's need satisfactorily.

Bobba, V.V.; Krishnamurthy, G.T.; Kingston, E.; Brown, P.H.; Eklem, M.; Turner, F.E.

1983-02-01

181

Two-dimensional, M-mode and Doppler-derived echocardiographic parameters in sedated healthy growing female sheep.  

PubMed

Despite the fact that sheep are a widely used animal model in cardiovascular research, reference values for transthoracic echocardiography in normal growing animals are not available. Eight healthy female lambs underwent two-dimensional, M-mode and pulsed wave Doppler echocardiographic examination at 100 days of age and every three months thereafter over a 12-month period. The study was conducted under sedation with midazolam, butorphanol and constant rate infusion of intravenous propofol. Their growth phase was completed at about one year of age. All the echocardiographic parameters considered were significantly correlated with body weight and age class except for the left ventricular systolic and diastolic diameters. Functional indices were not correlated to body weight or age except for the E-point to septal separation distance (EPSS). Doppler-derived parameters were not influenced by independent variables. Transthoracic echocardiography can be considered an applicable method for cardiovascular research using a growing lamb animal model after appropriate adjustments for age and body size. PMID:23760962

Poser, H; Semplicini, L; De Benedictis, G M; Gerardi, G; Contiero, B; Maschietto, N; Valerio, E; Milanesi, O; Semplicini, A; Bernardini, D

2013-07-01

182

The 27-28 October 1986 FIRE IFO Cirrus Case Study: Cirrus Parameter Relationships Derived from Satellite and Lidar Data  

NASA Technical Reports Server (NTRS)

Cirrus cloud radiative and physical characteristics are determined using a combination of ground-based, aircraft, and satellite measurements taken as part of the FIRE Cirrus Intensive Field Observations (IFO) during October and November 1986. Lidar backscatter data are used with rawinsonde data to define cloud base, center, and top heights and the corresponding temperatures. Coincident GOES 4-km visible (0.65 micro-m) and 8-km infrared window (11.5 micro-m) radiances are analyzed to determine cloud emittances and reflectances. Infrared optical depth is computed from the emittance results. Visible optical depth is derived from reflectance using a theoretical ice crystal scattering model and an empirical bidirectional reflectance model. No clouds with visible optical depths greater than 5 or infrared optical depths less than 0.1 were used in the analysis. Average cloud thickness ranged from 0.5 km to 8.0 km for the 71 scenes. Mean vertical beam emittances derived from cloud-center temperatures were 0.62 for all scenes compared to 0.33 for the case study (27-28 October) reflecting the thinner clouds observed for the latter scenes. Relationships between cloud emittance, extinction coefficients, and temperature for the case study are very similar to those derived from earlier surface- based studies. The thicker clouds seen during the other IFO days yield different results. Emittances derived using cloud-top temperature were ratioed to those determined from cloud-center temperature. A nearly linear relationship between these ratios and cloud-center temperature holds promise for determining actual cloud-top temperatures and cloud thicknesses from visible and infrared radiance pairs. The mean ratio of the visible scattering optical depth to the infrared absorption optical depth was 2.13 for these data. This scattering efficiency ratio shows a significant dependence on cloud temperature. Values of mean scattering efficiency as high as 2.6 suggest the presence of small ice particles at temperatures below 230 K. The parameterization of visible reflectance in terms of cloud optical depth and clear-sky reflectance shows promise as a simplified method for interpreting visible satellite data reflected from cirrus clouds. Large uncertainties in the optical parameters due to cloud reflectance anisotropy and shading were found by analyzing data for various solar zenith angles and for simultaneous AVHRR data. Inhomogeneities in the cloud fields result in uneven cloud shading that apparently causes the occurrence of anomalously dark, cloudy pixels in the GOES data. These shading effects complicate the interpretation of the satellite data. The results highlight the need for additional study of cirrus cloud scattering processes and remote sensing techniques.

Minnis, Patrick; Young, David F.; Sassen, Kenneth; Alvarez, Joseph M.; Grund, Christian J.

1990-01-01

183

Polymer-drug interactions in tyrosine-derived triblock copolymer nanospheres: a computational modeling approach.  

PubMed

A combination of molecular dynamics (MD) simulations and docking calculations was employed to model and predict polymer-drug interactions in self-assembled nanoparticles consisting of ABA-type triblock copolymers, where A-blocks are poly(ethylene glycol) units and B-blocks are low molecular weight tyrosine-derived polyarylates. This new computational approach was tested on three representative model compounds: nutraceutical curcumin, anticancer drug paclitaxel and prehormone vitamin D3. Based on this methodology, the calculated binding energies of polymer-drug complexes can be correlated with maximum drug loading determined experimentally. Furthermore, the modeling results provide an enhanced understanding of polymer-drug interactions, revealing subtle structural features that can significantly affect the effectiveness of drug loading (as demonstrated for a fourth tested compound, anticancer drug camptothecin). The present study suggests that computational calculations of polymer-drug pairs hold the potential of becoming a powerful prescreening tool in the process of discovery, development and optimization of new drug delivery systems, reducing both the time and the cost of the process. PMID:19650665

Costache, Aurora D; Sheihet, Larisa; Zaveri, Krishna; Knight, Doyle D; Kohn, Joachim

2009-01-01

184

Derivation and assessment of phase-shifted, disordered vector field models for frustrated solvent interactions.  

PubMed

The structure and properties of water at biological interfaces differ drastically from bulk due to effects including confinement and the presence of complicated charge distributions. This non-bulk-like behavior generally arises from water frustration, wherein all favorable interactions among water molecules cannot be simultaneously satisfied. While the frustration of interfacial water is ubiquitous in the cell, the role this frustration plays in mediating biophysical processes like protein folding is not well understood. To investigate the impact of frustration at interfaces, we here derive a general field theoretic model for the interaction of bulk and disordered vector fields at an embedded surface. We calculate thermodynamic and correlation functions for the model in two and three dimensions, and we compare our results to Monte Carlo simulations of lattice system analogs. In our analysis, we see that field-field cross correlations near the interface in the model give rise to a loss in entropy like that seen in glassy systems. We conclude by assessing our theory's utility as a coarse-grained model for water at polar biological interfaces. PMID:23464179

Weber, Jeffrey K; Pande, Vijay S

2013-02-28

185

Derivation and assessment of phase-shifted, disordered vector field models for frustrated solvent interactions  

NASA Astrophysics Data System (ADS)

The structure and properties of water at biological interfaces differ drastically from bulk due to effects including confinement and the presence of complicated charge distributions. This non-bulk-like behavior generally arises from water frustration, wherein all favorable interactions among water molecules cannot be simultaneously satisfied. While the frustration of interfacial water is ubiquitous in the cell, the role this frustration plays in mediating biophysical processes like protein folding is not well understood. To investigate the impact of frustration at interfaces, we here derive a general field theoretic model for the interaction of bulk and disordered vector fields at an embedded surface. We calculate thermodynamic and correlation functions for the model in two and three dimensions, and we compare our results to Monte Carlo simulations of lattice system analogs. In our analysis, we see that field-field cross correlations near the interface in the model give rise to a loss in entropy like that seen in glassy systems. We conclude by assessing our theory's utility as a coarse-grained model for water at polar biological interfaces.

Weber, Jeffrey K.; Pande, Vijay S.

2013-02-01

186

Leukocyte-endothelial cell adhesive interactions: role of xanthine oxidase-derived oxidants.  

PubMed

The objective of this study was to determine whether agents that either scavenge or inhibit the production of oxygen radicals can alter the adhesive interactions between leukocytes and venular endothelium elicited by ischemia-reperfusion. Cat mesenteric and intestinal blood flows were reduced to 20% of baseline for 1 hr, followed by 1 hr of reperfusion. Sixty minutes after reperfusion, red blood cell velocity (Vr), leukocyte rolling velocity (Vw), and the number of adherent leukocytes were measured in mesenteric venules. Then, either manganese-superoxide dismutase (Mn-SOD), catalase, desferrioxamine, or oxypurinol was administered intravascularly. Ten minutes later, repeat measurements were obtained and compared with pretreatment values. Catalase, Mn-SOD, and oxypurinol significantly attenuated neutrophil adherence while neither inactivated-catalase nor desferrioxamine altered the reperfusion-induced leukocyte adhesion. The ratio of Vw to erythrocyte velocity, an index of the fracture stress between rolling leukocytes and venular endothelium, was not altered by any of the agents studied. These results and data in the literature indicate that many of the agents that are commonly used to either scavenge or inhibit the production of oxygen radicals in postischemic tissues exert a significant inhibitory influence on leukocyte adhesion to microvascular endothelium in vivo. Our results are also consistent with the view that xanthine oxidase-derived oxidants contribute to the leukocyte-endothelial cell adhesive interactions associated with reperfusion of ischemic tissues. PMID:1748842

Suzuki, M; Grisham, M B; Granger, D N

1991-11-01

187

Micro-PIXE characterization of interactions between a sol gel derived bioactive glass and biological fluids  

NASA Astrophysics Data System (ADS)

Bioactive glasses possess the ability to bond to living tissues through the formation of a calcium phosphate-rich layer at their interface with living tissues. This paper reports the different steps of this bioactivity process via a complete micro-PIXE characterization of a sol-gel derived SiO 2-CaO bioactive glass in contact with biological fluids for different delays. Multi-elemental cartography at the glass/biological fluids interface together with major and trace elements quantification permit a better understanding of the five reaction stages involved in the bioactivity mechanisms. The presence of phosphorus was detected at the periphery of the material within 6 h of interaction with biological fluids. A calcium phosphate-rich layer containing magnesium is formed after a few days of interaction and presence of bone-like apatite is deduced from the calculation of the Ca/P ratio at the material interface. That is of deep interest for clinical applications, because this biologically active behavior results in the formation of a strong interfacial bond between the glass and host tissues, and will stimulate bone-cell proliferation.

Lao, J.; Nedelec, J. M.; Moretto, Ph.; Jallot, E.

2006-04-01

188

Polystyrene derivatives substituted with arginine interact with Babanki (Togaviridae) and Kedougou (Flaviviridae) viruses.  

PubMed

Outbreaks of new or old diseases appear primarily in tropical zones such as Africa, south and central America, or Asia. Among these diseases, those induced by Arboviruses (the best known of which are being yellow fever, dengue, Ebola, and Sindbis) are under intensive observation by the World Health Organization. Rapid isolation and identification of the viral species is the first step in the diagnosis, study, and control of epidemics. One major problem with the isolation of viruses is capturing sufficient numbers of viral particles to test. The work presented in this report addresses this question. We have tested the interaction between Babanki (Togaviridae), Kedougou (Flaviviridae) viruses, and a range of insoluble polystyrene derivatives substituted with arginine groups. Insoluble functionalized copolymers were found to develop specific interactions with viruses through chemical groups present on their surfaces. The adsorption of viruses varied according to the percentage of arginine substituted onto the polymer, with a maximum value for both viruses of about 20% of grafting rate. It was also found that the Kedougou virus displayed the highest affinity for this polymer. PMID:12601758

Imbert-Laurenceau, Emmanuelle; Crepinior, José; Crance, Jean-Marc; Jouan, Alain; Migonney, Véronique

2003-04-01

189

Unsymmetrical oxovanadium complexes derived from salicylaldehyde and phenanthroline: synthesis, DNA interactions, and antitumor activities.  

PubMed

Two unsymmetrical oxovanadium complexes incorporating salicylaldehyde derivate and phenanthroline [VO(DESAA)(phen)] (1), (DESAA = 4-(diethylamino)salicylaldehyde anthranilic acid, phen = phenanthroline) and [VO(CLSAA)(phen)] (2), (CLSAA = 5-chlorosalicylaldehyde anthranilic acid)] have been synthesized and characterized. The interactions of the complexes with CT-DNA were studied using different techniques. Complexes 1 and 2 interact with CT-DNA by intercalative modes and can efficiently cleave pBR322 DNA after light irradiation. The two complexes showed high cytotoxic activities against myeloma cell (Ag8.653) and gliomas cell (U251) lines. Interestingly, complex 1 exhibited greater antitumor efficiency, larger binding affinity with CT-DNA, and better cleaving ability than those of complex 2. In addition, their antitumor mechanism has been analyzed by using cell cycle analysis, apoptosis, and Annexin V-FITC/PI assay. The results showed that complex 1 can cause G2/M-phase arrest of the cell cycle, exhibit a significantly induced apoptosis in Ag8.653 cells, and display typical morphological apoptotic characteristics. These complexes induced proliferative suppression of Ag8.653 cells via the induction of apoptosis. PMID:24118856

Liao, Xiangwen; Pan, Weijian; He, Rongwei; Guo, Haiwei; Ying, Peng; Lu, Jiazheng

2014-03-01

190

A Combined Experimental and Computational Study of Vam3, a Derivative of Resveratrol, and Syk Interaction  

PubMed Central

Spleen tyrosine kinase (Syk) plays an indispensable role through preliminary extracellular antigen-induced crosslinking of Fc receptor (FcR) in the pathogenesis of autoimmune disorders, such as rheumatoid arthritis. In this study, we identify Vam3, a dimeric derivative of resveratrol isolated from grapes, as an ATP-competitive inhibitor of Syk with an IC50 of 62.95 nM in an in vitro kinase assay. Moreover, docking and molecular dynamics simulation approaches were performed to get more detailed information about the binding mode of Vam3 and Syk. The results show that 11b-OH on ring-C and 4b-OH on ring-D could form two hydrogen bonds with Glu449 and Phe382 of Syk, respectively. In addition, arene-cation interaction between ring-D of Vam3 and Lys402 of Syk was also observed. These results indicate that ring-C and D play an essential role in Vam3–Syk interaction. Our studies may be helpful in the structural optimization of Vam3, and also aid the design of novel Syk inhibitors in the future. PMID:25257535

Jiang, Ming; Liu, Renping; Chen, Ying; Zheng, Qisheng; Fan, Saijun; Liu, Peixun

2014-01-01

191

A combined experimental and computational study of vam3, a derivative of resveratrol, and syk interaction.  

PubMed

Spleen tyrosine kinase (Syk) plays an indispensable role through preliminary extracellular antigen-induced crosslinking of Fc receptor (FcR) in the pathogenesis of autoimmune disorders, such as rheumatoid arthritis. In this study, we identify Vam3, a dimeric derivative of resveratrol isolated from grapes, as an ATP-competitive inhibitor of Syk with an IC50 of 62.95 nM in an in vitro kinase assay. Moreover, docking and molecular dynamics simulation approaches were performed to get more detailed information about the binding mode of Vam3 and Syk. The results show that 11b-OH on ring-C and 4b-OH on ring-D could form two hydrogen bonds with Glu449 and Phe382 of Syk, respectively. In addition, arene-cation interaction between ring-D of Vam3 and Lys402 of Syk was also observed. These results indicate that ring-C and D play an essential role in Vam3-Syk interaction. Our studies may be helpful in the structural optimization of Vam3, and also aid the design of novel Syk inhibitors in the future. PMID:25257535

Jiang, Ming; Liu, Renping; Chen, Ying; Zheng, Qisheng; Fan, Saijun; Liu, Peixun

2014-01-01

192

Structural connectivity and ionic transport in molten ZnCl 2: Optimization of chlorine interaction parameters  

NASA Astrophysics Data System (ADS)

We report molecular-dynamics simulations of pseudoclassical models of liquid ZnCl 2 near its standard freezing point (sfp) and in thermodynamic states at higher temperature and pressure. Our calculations are firstly aimed at investigating the model sensitivity of the results for the temperature-dependent self-diffusion coefficients of the two species and for the structural connectivity of the liquid as defined in terms of corner-sharing versus edge-sharing ZnCl 4 tetrahedra. Data from coherent neutron scattering experiments near the sfp and from ionic diffusivity measurements along the standard-pressure isobar guide us to a “best” choice of the model parameters describing the electric polarizability and the van der Waals interaction coefficient of the chlorine ions. This choice also provides a consistent picture of the behaviour of the liquid under pressure: with increasing pressure the Zn ions are progressively squeezed from fourfold into sixfold coordination sites, in correspondence to crystal structures built on these two coordination states. The proposed “best” interionic force law is further tested by comparing its predictions with existing first-principles calculations on the structure of the molecular dimer Zn 2Cl 4 and with new first-principles calculations on distorted configurations of the ZnCl 2 monomer as created by extensive bond stretching or bond bending.

Ruberto, R.; Pastore, G.; Tosi, M. P.

2010-02-01

193

Low-intensity millimeter wave electromagnetic radiation influence upon nuclear-lattice interaction parameters in water media  

Microsoft Academic Search

A behavior of aqueous solutions contained oxygen was studied. These solutions simulated the low-molecular liquid homeostasis of human organism. The environment parameters variations radical influence the nature of physical interaction between oxygen and water molecules in the presence of an O2 of supercritical concentration was shown. Transformations of the 'free' and 'connected' H2O fractions were controlled by environment parameters, in

Ye. A. Andreyev; I. A. Ivanchenko; N. G. Nikishina; L. V. Sveshnikova

1994-01-01

194

Juxtacrine and Paracrine Interactions of Rat Marrow-Derived Mesenchymal Stem Cells, Muscle-Derived Satellite Cells, and Neonatal Cardiomyocytes with Endothelial Cells in Angiogenesis Dynamics  

PubMed Central

Research into angiogenesis has contributed to progress in the fast-moving field of regenerative medicine. Designing coculture systems is deemed a helpful method to understand the dynamic interaction of various cells involved in the angiogenesis process. We investigated the juxtacrine and paracrine interaction between 3 different cells, namely rat marrow-derived mesenchymal stem cells (rMSCs), rat muscle-derived satellite cells (rSCs), and rat neonatal cardiomyocytes (rCMs), and endothelial cells (ECs) during angiogenesis process. In vitro Matrigel angiogenesis assay was performed whereby ECs were monocultured or cocultured with rMSCs, rSCs, and rCMs or their conditioned media (CM). In addition, in vivo Matrigel plug assay for angiogenesis was conducted to assess the angiogenic potential of the rCM-, rMSC-, and rSC-derived CM. Our results demonstrated that the rMSCs, rSCs, and rCMs elongated along the EC tubules, whereas the rMSCs formed tube-like structures with sprouting tip cells, leading to improved angiogenesis in the coculture system. Moreover, the rMSC- and rSC-derived CM significantly improved angiogenesis tube formation on Matrigel, accelerated EC chemotaxis, and increased the arteriolar density, vascularization index, and vascularization flow index in the Matrigel plug in vivo. Western blotting showed that rMSCs secreted a high level of vascular endothelial growth factor, basic fibroblast growth factor, and stromal-derived factor-1-alpha. Tie2 is also shed from rMSCs. This study demonstrated that stem cells interact with ECs in the juxtacrine and paracrine manner during angiogenesis, and marrow MSCs have superior angiogenic properties. PMID:23072248

Rahbarghazi, Reza; Khazraiinia, Parvaneh; Kajbafzadeh, Abdol-Mohammad; Ahmadi, Seyed Hossein; Mohammadi, Elham; Molazem, Mohammad; Zamani-Ahmadmahmudi, Mohamad

2013-01-01

195

Best values of parameters for interacting HDE with GO IR-cutoff in Brans-Dicke cosmology  

E-print Network

We investigate the interacting holographic dark energy (HDE) with Granda-Oliveros (GO) IR-cutoff in the framework of Brans-Dicke (BD) cosmology. We obtain the equation of state (EoS) parameter of HDE, $w_D$, the effective EoS parameter $w_{\\mathrm{eff}}$, the deceleration parameter $q $ and the squared of sound speed $v_s^2$ in a flat FRW universe. We show that at late time the cosmic coincidence problem can be alleviated. Also we show that for non-interacting case, HDE can give a unified dark matter-dark energy profile in BD cosmology, except that it cannot solve the coincidence problem in the future. By studying the equation of state parameter, we see that the phantom divide may be crossed. Using the latest observational data, we calculate the best values of the parameters for interacting HDE in BD framework. Computing the deceleration parameter implies that the transition from deceleration to the acceleration phase occurred for redshift $z\\geq 0.5$. Finally, we investigate the sound stability of the model, and find that HDE with GO cutoff in the framework of BD cosmology can lead to a stable DE-dominated universe favored by observations, provided we take $\\beta=0.44$ and $b^2<0.35$. This is in contrast to HDE model in Einstein gravity which does not lead to a stable DE dominated universe.

A. Khodam-Mohammadi; E. Karimkhani; A. Sheykhi

2014-09-09

196

Correlation of Intra-Tumor 18F-FDG Uptake Heterogeneity Indices with Perfusion CT Derived Parameters in Colorectal Cancer  

PubMed Central

Application of textural features analysis to 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) images has been used to characterize intra-tumor uptake heterogeneity and has been shown to reflect disease outcome. A current hypothesis is that 18F-FDG uptake heterogeneity may reflect the physiological tracer uptake related to tumor perfusion. The purpose of our study was to investigate the correlations between intra-tumor uptake heterogeneity and vascular parameters derived from dynamic contrast enhanced (DCE) computed tomography (CT) obtained from an integrated 18F-FDG PET/perfusion CT examination. Methods Thirty patients with proven colorectal cancer prospectively underwent integrated 18F-FDG PET/DCE-CT to assess the metabolic-flow phenotype. Both CT blood flow parametric maps and PET images were analyzed. Correlations between PET heterogeneity and perfusion CT were assessed by Spearman's rank correlation analysis. Results Blood flow visualization provided by DCE-CT images was significantly correlated with 18F-FDG PET metabolically active tumor volume as well as with uptake heterogeneity for patients with stage III/IV tumors (|?|:0.66 to 0.78; p-value<0.02). Conclusion The positive correlation found with tumor blood flow indicates that intra-tumor heterogeneity of 18F-FDG PET accumulation reflects to some extent tracer distribution and consequently indicates that 18F-FDG PET intra-tumor heterogeneity may be associated with physiological processes such as tumor vascularization. PMID:24926986

Tixier, Florent; Groves, Ashley M.; Goh, Vicky; Hatt, Mathieu; Ingrand, Pierre; Le Rest, Catherine Cheze; Visvikis, Dimitris

2014-01-01

197

Cytotoxicity of mitochondria-targeted resveratrol derivatives: interactions with respiratory chain complexes and ATP synthase.  

PubMed

We recently reported that mitochondria-targeted derivatives of resveratrol are cytotoxic in vitro, selectively inducing mostly necrotic death of fast-growing and tumoral cells when supplied in the low ?M range (N. Sassi et al., Curr. Pharm. Des. 2014). Cytotoxicity is due to H2O2 produced upon accumulation of the compounds into mitochondria. We investigate here the mechanisms underlying ROS generation and mitochondrial depolarization caused by these agents. We find that they interact with the respiratory chain, especially complexes I and III, causing superoxide production. "Capping" free hydroxyls with acetyl or methyl groups increases their effectiveness as respiratory chain inhibitors, promoters of ROS generation and cytotoxic agents. Exposure to the compounds also induces an increase in the occurrence of short transient [Ca(2+)] "spikes" in the cells. This increase is unrelated to ROS production, and it is not the cause of cell death. These molecules furthermore inhibit the F0F1 ATPase. When added to oligomycin-treated cells, the acetylated/methylated ones cause a recovery of the cellular oxygen consumption rates depressed by oligomycin. Since a protonophoric futile cycle which might account for the uncoupling effect is impossible, we speculate that the compounds may cause the transformation of the ATP synthase and/or respiratory chain complex(es) into a conduit for uncoupled proton translocation. Only in the presence of excess oligomycin the most effective derivatives appear to induce the mitochondrial permeability transition (MPT) within the cells. This may be considered to provide circumstantial support for the idea that the ATP synthase is the molecular substrate for the MPT pore. PMID:24997425

Sassi, Nicola; Mattarei, Andrea; Azzolini, Michele; Szabo', Ildiko'; Paradisi, Cristina; Zoratti, Mario; Biasutto, Lucia

2014-10-01

198

Bilateral interaction between cord blood-derived human neural stem cells and organotypic rat hippocampal culture.  

PubMed

The umbilical cord blood-derived neural stem/progenitor cells (HUCB-NSCs) potentially represent a rich source of transplantable material for treatment of a wide range of neurological diseases. Although, recently reported effects of their implementation in animal models of brain pathology are still controversial. As a simplified alternative to in vivo transplantation in this work we have applied a long-term organotypic rat hippocampal slice culture (OHC) as a recipient tissue to study bilateral graft/host cells interactions ex vivo. This type of culture can be considered as a kind of reductionistic model of brain transplantation where direct influence of systemic immunological responses to transplanted human cells would be excluded. The transplantation material derived from a HUCB-NSC line developed and characterized in our laboratory and delivered to the slices either as a single-cell suspension or after formation of typical neurospheres in serum-free medium in vitro (N-HUCBs). Experiments were focused on space-temporal context of cell transplantation in relation to their ability to ingrown, migrate, and differentiate within the slice cytoarchitecture. We gain evidences that these responses are strictly dependent on the engraftment site and that cell movement reflects typical routes used for migratory neuroblasts in vivo. The cells implanted at the second week of slice cultivation ingrown readily and deeply into host cytoarchitecture then matured to the level never observed in our transplantation animal models in vivo. Importantly, transplanted neurospheres, in addition to yield exogenous migratory cells to the host tissue can locally inhibit astrocytosis and promote outgrow of DCX-reactive neuroblasts in the surrounding OHC tissue. PMID:19053232

Sarnowska, Anna; Jurga, Marcin; Buza?ska, Leonora; Filipkowski, Robert K; Duniec, Kamila; Doma?ska-Janik, Krystyna

2009-10-01

199

Quantifying parameter sensitivity, interaction, and transferability in hydrologically enhanced versions of the Noah land surface model  

E-print Network

,2 Zong-Liang Yang,1 Thorsten Wagener,3 Lindsey E. Gulden,1,2 Soni Yatheendradas,4,5 and Guo-Yue Niu6 parameters, and the covariance structure of the distribution of behavioral parameter sets. Using Sobol0 's evaporation and base flow. Unsupervised classification of the posterior distributions of behavioral parameter

Wagener, Thorsten

200

Understanding the stereospecific interactions of 3-deoxyphosphatidylinositol derivatives with the PTEN phosphatase domain  

PubMed Central

PTEN is an important control element of PI3K/AKT signaling involved in controlling the processes of embryonic development, cell migration and apoptosis. While its dysfunction is implicated in a large fraction of cancers, PTEN activity in the same pathway may also contribute to metabolic syndromes such as diabetes. In those cases, selective inhibitors of PTEN may be useful. A new class of chiral PTEN inhibitors based on the 3-deoxy-phosphatidylinositol derivatives was recently identified [Wang et al. (2008) J. Am. Chem. Soc. 130, 7746]. However, lack of detailed understanding of protein-ligand interactions has hampered efforts to develop effective agonists or antagonists of PTEN. Here, we use computational modeling to characterize the interactions of the diverse 3-deoxyphosphatidylinositol inhibitors with the PTEN protein. We show that, while each of the compounds binds with the inositol headgroup inserting into the proposed active site of the PTEN phosphatase domain, hydrogen bonding restrictions lead to distinct binding geometries for ligand pairs of opposite chirality. We furthermore demonstrate that the binding modes differ primarily in the orientation of acyl tails of the ligands and that the activity of the compounds is primarily controlled by the effectiveness of tail-protein contacts. These findings are confirmed by binding affinity calculations which are in good agreement with experiment. Finally, we show that while more potent D-series ligands bind in a manner similar to that of the native substrate, an alternate hydrophobic pocket suitable for binding the opposite chirality L-series inhibitors exists, offering the possibility of designing highly selective PTEN- targeting compounds. PMID:20538496

Wang, Qin; Wei, Yang; Mottamal, Madhusoodanan; Roberts, Mary F.; Krilov, Goran

2011-01-01

201

Biophysical analysis of the interaction of granulysin-derived peptides with enterobacterial endotoxins  

PubMed Central

To combat infections by Gram-negative bacteria, it is not only necessary to kill the bacteria but also to neutralize pathogenicity factors such as endotoxin (lipopolysaccharide, LPS). The development of antimicrobial peptides based on mammalian endotoxin-binding proteins is a promising tool in the fight against bacterial infections, and septic shock syndrome. Here, synthetic peptides derived from granulysin (Gra-pep) were investigated in microbiological and biophysical assays to understand their interaction with LPS. We analyzed the influence of the binding of Gra-pep on (1) the acyl chain melting of the hydrophobic moiety of LPS, lipid A, by Fourier-transform spectroscopy, (2) the aggregate structure of LPS by small-angle X-ray scattering and cryo-transmission electron microscopy, and 3) the enthalpy change by isothermal titration calorimetry. In addition, the influence of Gra-pep on the incorporation of LPS and LPS-LBP (lipopolysaccharide-binding protein) complexes into negatively charged liposomes was monitored. Our findings demonstrate a characteristic change in the aggregate structure of LPS into multilamellar stacks in the presence of Gra-pep, but little or no change of acyl chain fluidity. Neutralization of LPS by Gra-pep is not due to a scavenging effect in solution, but rather proceeds after incorporation into target membranes, suggesting a requisite membrane-bound step. PMID:17555705

Chen, Xi; Howe, Jorg; Andra, Jorg; Rossle, Manfred; Richter, Walter; Silva, Ana Paula Galvao da; Krensky, Alan M.; Clayberger, Carol; Brandenburg, Klaus

2009-01-01

202

Insight into the Interactions between Novel Coumarin Derivatives and Human A3 Adenosine Receptors.  

PubMed

A study focused on the discovery of new chemical entities based on the 3-arylcoumarin scaffold was performed with the aim of finding new adenosine receptor (AR) ligands. Thirteen synthesized compounds were evaluated by radioligand binding (A1 , A2A , and A3 ) and adenylyl cyclase activity (A2B ) assays in order to study their affinity for the four human AR (hAR) subtypes. Seven of the studied compounds proved to be selective A3 AR ligands, with 3-(4'-methylphenyl)-8-(2-oxopropoxy)coumarin (12) being the most potent (Ki =634?nM). None of the compounds showed affinity for the A2B receptor, while four compounds were found to be nonselective AR ligands for the other three subtypes. Docking simulations were carried out to identify the hypothetical binding mode and to rationalize the interaction of these types of coumarin derivatives with the binding site of the three ARs to which binding was observed. The results allowed us to conclude that the 3-arylcoumarin scaffold composes a novel and promising class of A3 AR ligands. ADME properties were also calculated, with the results suggesting that these compounds are promising leads for the identification of new drug candidates. PMID:25044491

Matos, Maria João; Vilar, Santiago; Kachler, Sonja; Fonseca, André; Santana, Lourdes; Uriarte, Eugenio; Borges, Fernanda; Tatonetti, Nicholas P; Klotz, Karl-Norbert

2014-10-01

203

Molecular Pathways: Tumor-derived microvesicles and their interactions with immune cells in vivo  

PubMed Central

Cancer is not merely a cell-intrinsic genetic disease, but also the result of complex cell-extrinsic interactions with host components, including immune cells. For example, effector T lymphocytes and NK cells are thought to participate in an immunosurveillance process which eliminates neoplastic cells, whereas regulatory T lymphocytes and some myeloid cells, including macrophages, can create a milieu that prevents anti-tumor activity, supports tumor growth and reduces survival of the host. Increasing evidence supports the notion that carcinoma cells communicate with immune cells directly, both within and away from the tumor stroma, and that this process fosters suppression of immunosurveillance and promotes tumor outgrowth. An important mode of communication between carcinoma cells and immune cells may involve tumor-derived microvesicles (tMVs), also known as exosomes, ectosomes, or microparticles. These microvesicles carry lipids, proteins, mRNAs and miRNAs, and travel short or long distances to deliver undegraded and undiluted material to other cells. Here we consider the capacity of tMVs to control tumor-associated immune responses, and highlight the known and unknown tMV’s actions in vivo. We also discuss why microvesicles may play a role in cancer diagnostics and prognostics, and how they could be harnessed for anti-cancer therapy. PMID:23426276

Pucci, Ferdinando; Pittet, Mikael J

2013-01-01

204

Interactions of a Platinum-Modified Perylene Derivative with the Human Telomeric G-Quadruplex  

PubMed Central

The interactions of a newly synthesized platinum-modified perylene derivative, compound 7 ([{Pt(dien)}2(?-4-S,S')](NO3)4 (dien = diethylenetriamine, 4 = N,N'-bis(1-(2-aminoethyl)-1,3-dimethylthiourea)-3,4,9,10-perylenetetracarboxylic acid diimide), with the human telomeric repeat were studied using various model oligo(deoxy)ribonucleotides to mimic the polymorphic nature of the telomeric G-quadruplex. UV/visible spectroscopy, CD spectropolarimetry, electrospray mass spectrometry (ES-MS), and isothermal titration calorimetry (ITC) were used to demonstrate that compound 7 selectively recognizes the antiparallel form of the unimolecular telomeric G-quadruplex formed by the sequence d(TTAGGG)4 (dG-24), to which it binds with a 2:1 stoichiometry and nanomolar affinity. Compared with telomeric DNA, the first binding event of compound 7 in titrations with the RNA quadruplex formed by r(UUAGGG)4 (rG-24) is an order of magnitude weaker. Compound 7 does not induce the antiparallel G-quadruplex RNA, which invariably exists in a parallel form and dimerizes in solution. Based on the cumulative experimental data, two distinct mechanisms are proposed for the recognition of G-quadruplex DNA and RNA by compound 7. Potential biomedical and biochemical applications of the platinum–perylene technology are discussed. PMID:21999566

Rao, Lu; Dworkin, Joshua D.; Nell, William E.; Bierbach, Ulrich

2012-01-01

205

Spontaneous H2 loss through the interaction of squaric acid derivatives and BeH2.  

PubMed

The most stable complexes between squaric acid and its sulfur- and selenium-containing analogues (C4X4H2 ; X = O, S, Se) with BeY2 (Y = H, F) were studied by means of the Gaussian?04 (G4) composite ab initio theory. Squaric acid derivatives are predicted to be very strong acids in the gas phase; their acidity increases with the size of the chalcogen, with C4Se4H2 being the strongest acid of the series and stronger than sulfuric acid. The relative stability of the C4X4H2?BeY2 (X = O, S, Se; Y = H, F) complexes changes with the nature of the chalcogen atom; but more importantly, the formation of the C4X4H2?BeF2 complexes results in a substantial acidity enhancement of the squaric moiety owing to the dramatic electron-density redistribution undergone by the system when the beryllium bond is formed. The most significant consequence of this acidity enhancement is that when BeF2 is replaced by BeH2, a spontaneous exergonic loss of H2 is observed regardless of the nature of the chalcogen atom. This is another clear piece of evidence of the important role that closed-shell interactions play in the modulation of physicochemical properties of the Lewis acid and/or the Lewis base. PMID:24665080

Montero-Campillo, M Merced; Yáñez, Manuel; Lamsabhi, Al Mokhtar; Mó, Otilia

2014-04-25

206

Stacking interactions of nucleobases: NMR-investigations. II. Self-association of purine-and pyrimidine-derivatives.  

PubMed

The self-association of various purine- and pyrimidine-derivatives in D2O has been studied by means of NMR technique. The thermodynamic quantities have been calculated using an isodesmic NMR model. Among the nucleobases investigated, the adenine-derivatives were found to be most suitable for quantitative determination. A comparison of methylated adenine-derivatives and the pH-dependence of the self-association lead to the conlcusion, that the stacking associates are stabilized by special van der Waals interactions based, essentially, on the polarizability of the pi-electron-system of the assciated molecules. PMID:1234031

Schimmack, W; Sapper, H; Lohmann, W

1975-12-19

207

Investigating earthquake self-similarity using a 20 year catalog of source parameters derived from InSAR data  

NASA Astrophysics Data System (ADS)

The question of how moment release in earthquakes scales to other earthquake source parameters, such as fault length and average slip, is a long-standing controversy (e.g. Scholz, 1982, 1994; Romanowicz, 1992). It is a problem that speaks to issues of earthquake source mechanics, specifically the self-similarity of earthquakes - is stress drop constant across all magnitudes? Theoretically, two end-member scaling models have been proposed - the so-called ';W-model', whereby seismic moment scales linearly with fault length, and the alternative ';L-model', where moment scales with the square of fault length. Existing data on earthquake rupture dimensions, typically from field observations or aftershock locations, do not conclusively favor one over the other. A W-model implies a constant stress drop for all earthquakes in the same tectonic setting, and therefore that earthquakes are self-similar. The L-model does not imply self-similarity, but is consistent with the idea that ';large earthquakes' (i.e. earthquakes that rupture the full thickness of the brittle upper crust) grow by increasing their rupture length, with average slip being proportional to fault length. To address this problem, we use a compilation of source parameter information from over 130 published studies of 101 individual earthquakes (Mw 4.7-9.0) studied using InSAR. There are several reasons to suggest that this information will be highly suitable for the study of earthquake scaling. The high spatial resolution and centimetric precision of InSAR data provide strong constraints on estimates of fault length and slip. In addition, in a previous study, we found good agreement between moment estimates from InSAR studies and the Global CMT catalog, derived from long-period seismic data (Weston et al., 2011). Considering events of all mechanisms together, we find a scaling relationship between moment (M0) and fault length (L), such that M0 ? L1.8. We find differences in this power law exponent with mechanism type, with thrust events showing an exponent of 2.0, consistent with L-model scaling, and strike-slip events an exponent of 1.6. These results do not favor self-similarity, however some authors have suggested that both self-similarity and quasi-L model scaling could be maintained if earthquake slip in the largest events penetrates beneath the brittle-ductile transition (Shaw and Wesnousky, 2008). Systematic comparisons of the depths of the base of the slipping zone from large earthquakes, compared with seismic evidence such as the depths of microseismicity and/or aftershocks in the epicentral areas may be one way of evaluating this hypothesis in future.

Funning, G.; Ferreira, A. M.; Weston, J. M.; Bloomfield, H.

2013-12-01

208

Vehicle-derived emissions and pollution on the road autovia 2 investigated by rock-magnetic parameters: A case study from Argentina  

Microsoft Academic Search

In this work, we carried out a preliminary study of traffic-derived pollutants from primary sources (vehicles), and on roads\\u000a (paved area), road borders and surroundings areas. The study is focussed on the identification, distribution and concentration\\u000a of pollutants and magnetic carriers. Magnetic parameters and their analyses suggest that the magnetic signal of vehicle-derived\\u000a emissions is controlled by a magnetite-like phase.

Débora C. Marié; Marcos A. E. Chaparro; Claudia S. G. Gogorza; Ana Navas; Ana M. Sinito

2010-01-01

209

Derivatives of any order of the confluent hypergeometric function {sub 1}F{sub 1}(a,b,z) with respect to the parameter a or b  

SciTech Connect

The derivatives to any order of the confluent hypergeometric (Kummer) function F={sub 1}F{sub 1}(a,b,z) with respect to the parameter a or b are investigated and expressed in terms of generalizations of multivariable Kampe de Feriet functions. Various properties (reduction formulas, recurrence relations, particular cases, and series and integral representations) of the defined hypergeometric functions are given. Finally, an application to the two-body Coulomb problem is presented: the derivatives of F with respect to a are used to write the scattering wave function as a power series of the Sommerfeld parameter.

Ancarani, L. U. [Laboratoire de Physique Moleculaire et des Collisions, Universite Paul Verlaine-Metz, 57078 Metz (France); Gasaneo, G. [Departamento de Fisica, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8000 Bahia Blanca, Buenos Aires (Argentina)

2008-06-15

210

Best values of parameters for interacting HDE with GO IR-cutoff in Brans-Dicke cosmology  

NASA Astrophysics Data System (ADS)

We investigate the interacting holographic dark energy (HDE) with Granda-Oliveros (GO) infrared (IR)-cutoff in the framework of Brans-Dicke (BD) cosmology. We obtain the equation of state (EoS) parameter of HDE, wD, the effective EoS parameter weff, the deceleration parameter q and the squared of sound speed vs2 in a flat Friedmann-Robertson-Walker (FRW) universe. We show that at late-time the cosmic coincidence problem can be alleviated. Also we show that for noninteracting case, HDE can give a unified dark matter-dark energy (DM-DE) profile in BD cosmology, except that it cannot solve the coincidence problem in the future. By studying the EoS parameter, we see that the phantom divide may be crossed. Using the latest observational data, we calculate the best values of the parameters for interacting HDE in BD framework. Computing the deceleration parameter implies that the transition from deceleration to the acceleration phase occurred for redshift z ? 0.5. Finally, we investigate the sound stability of the model, and find that HDE with Granda-Oliveros (GO)-cutoff in the framework of BD cosmology can lead to a stable DE-dominated universe favored by observations, provided we take ? = 0.44 and b2 < 0.35. This is in contrast to HDE model in Einstein gravity which does not lead to a stable DE-dominated universe.

Khodam-Mohammadi, A.; Karimkhani, E.; Sheykhi, A.

2014-09-01

211

Derivation of a stochastic cellular automaton model for the dynamics of bistable units with global and asymmetric local interactions  

NASA Astrophysics Data System (ADS)

By means of ultradiscretization and probabilistic treatment, we derive a stochastic cellular automaton (CA) model from a dynamical model for bistable units with global and asymmetric local interactions. The obtained CA model is composed of the elementary CA rule 254 with a probabilistic rule that regulates the average of the total cell states.

Ohmori, Shousuke; Yamazaki, Yoshihiro

2014-08-01

212

Ascaris suum-Derived Products Induce Human Neutrophil Activation via a G Protein-Coupled Receptor That Interacts with the Interleukin-8 Receptor Pathway  

PubMed Central

Infection with tissue-migrating helminths is frequently associated with intense granulocyte infiltrations. Several host-derived factors are known to mediate granulocyte recruitment to the tissues, but less attention has been paid to how parasite-derived products trigger this process. Parasite-derived chemotactic factors which selectively recruit granulocytes have been described, but nothing is known about which cellular receptors respond to these agents. The effect of products from the nematodes Ascaris suum, Toxocara canis, and Anisakis simplex on human neutrophils were studied. We monitored four parameters of activation: chemotaxis, cell polarization, intracellular Ca2+ transients, and priming of superoxide anion production. Body fluids of A. suum (ABF) and T. canis (TcBF) induced strong directional migration, shape change, and intracellular Ca2+ transients. ABF also primed neutrophils for production of superoxide anions. Calcium mobilization in response to A. suum-derived products was completely abrogated by pretreatment with pertussis toxin, implicating a classical G protein-coupled receptor mechanism in the response to ABF. Moreover, pretreatment with interleukin-8 (IL-8) completely abrogated the response to ABF, demonstrating desensitization of a common pathway. However, ABF was unable to fully desensitize the response to IL-8, and binding to CXCR1 or CXCR2 was excluded in experiments using RBL-2H3 cells transfected with the two human IL-8 receptors. Our results provide the first evidence for a direct interaction between a parasite-derived chemotactic factor and the host's chemotactic network, via a novel G protein-coupled receptor which interacts with the IL-8 receptor pathway. PMID:11349070

Falcone, Franco H.; Rossi, Adriano G.; Sharkey, Rose; Brown, Alan P.; Pritchard, David I.; Maizels, Rick M.

2001-01-01

213

Prediction of drug-polymer miscibility through the use of solubility parameter based Flory-Huggins interaction parameter and the experimental validation: PEG as model polymer.  

PubMed

Important consideration for developing physically stable solid dispersion is miscibility of drug in carrier matrix. It is possible to predict thermodynamics of binary system through free energy calculations based on Flory-Huggins interaction parameter (?(dp)). In present study, PEG 6000 as model polymer and dataset comprising commonly used drugs/excipients was selected. The three-dimensional solubility parameter based on group contribution method was utilized for systemic calculation of ?(dp) of the polymer with each compound in data set. On the basis of the values of ?(dp), it was possible to categorize all the compounds into three distinct categories, Types I and II: compounds predicted to be miscible and immiscible respectively with the polymer in all proportions and Type III: compounds expected to exhibit composition dependent miscibility behavior. The Bagley plot showed that majority of points for Type I fall in a region, which can approximately be delimited by a circle. Experimental verification through thermal analysis revealed that though it was possible to predict correctly miscibility behavior of Type II class compounds, distinction between Types I and III was less evident. Hence, solubility parameter based ?(dp) may be used as an initial tool for fast screening of immiscible combination of polymer and drug. PMID:23649486

Thakral, Seema; Thakral, Naveen K

2013-07-01

214

Plasma-derived mannose-binding lectin shows a direct interaction with C1-inhibitor.  

PubMed

MBL-deficiency has been associated with an increased frequency and severity of infection, in particular in children and under immunocompromized conditions. In an open uncontrolled safety and pharmacokinetic MBL-substitution study using plasma-derived MBL (pdMBL) in MBL-deficient pediatric oncology patients, we found that despite MBL trough levels above 1.0?g/ml MBL functionality was not efficiently restored upon ex vivo testing. PdMBL showed C4-converting activity by itself, indicating the presence of MASPs. Upon incubation of pdMBL with MBL-deficient sera this C4-converting activity was significantly reduced. Depletion of the MASPs from pdMBL, paradoxically, restored the C4-converting activity. Subsequent depletion or inhibition of C1-inh, the major inhibitor of the lectin pathway, in the recipient serum restored the C4-converting activity as well. Complexes between MBL/MASPs and C1-inh (MMC-complexes) were detected after ex vivo substitution of MBL-deficient serum with pdMBL. These MMC-complexes could also be detected in the sera of the patients included in the MBL-substitution study shortly after pdMBL infusion. Altogether, we concluded that active MBL-MASP complexes in pdMBL directly interact with C1-inh in the recipient, leading to the formation of a multimolecular complex between C1-inh and MBL/MASPs, in contrast to the classical pathway where C1r and C1s are dissociated from C1q by C1-inh. Because of the presence of activated MASPs in the current pdMBL products efficient MBL-mediated host protection cannot be expected because of the neutralizing capacity by C1-inh. PMID:24368318

Keizer, Mischa P; Kamp, Angela M; Brouwer, Nannette; van de Wetering, Marianne D; Wouters, Diana; Kuijpers, Taco W

2014-04-01

215

Interpretation of the structural parameters derived from the analysis of polymer colloids by small-angle X-ray and neutron scattering  

Microsoft Academic Search

We reconsider the analysis of the structure of colloidal particles by small-angle scattering. Special emphasis is laid on the structural parameters derived from a small-angle experiment conducted at different contrast. The forward scattering of the particles, their radius of gyration and the invariant are reconsidered in terms of a model introduced by Harrison (1969). Here the finite resolution of the

P. Hickl; M. Ballauff

1997-01-01

216

Eur J Nucl Med Mol Imaging . Author manuscript Baseline F-FDG PET image-derived parameters for therapy response18  

E-print Network

to therapy ; PET scan ; tumour volume ; total lesion glycolysis Introduction Oesophageal cancer is the thirdEur J Nucl Med Mol Imaging . Author manuscript Page /1 16 Baseline F-FDG PET image-derived parameters for therapy response18 prediction in oesophageal cancer Mathieu Hatt 1 * , Dimitris Visvikis 1

Paris-Sud XI, Université de

217

Characterization of poly-Si thin-film solar cell functions and parameters with IR optical interaction techniques  

Microsoft Academic Search

Three different optical interaction techniques have been employed to characterise the electrical and material parameters of\\u000a polycrystalline silicon (poly-Si) thin-film solar cells with an interdigitated mesa structure. First, Light Beam Induced Current\\u000a (LBIC) in the infrared range was used to locally analyse the light collection properties. Second, electroluminescence in forward\\u000a bias (EL) yielding information on band to band recombination was

M. Boostandoost; F. Friedrich; U. Kerst; C. Boit; S. Gall; Y. Yokoyama

218

Interacting fluctuations and the two-loop order parameters of the strong-coupling negative- U Hubbard model  

Microsoft Academic Search

The effective field theory that describes the interaction of fluctuations of the attractive Hubbard model in the strong-coupling limit is formulated and applied to obtain the two-loop results for the order parameters of the model at low temperatures and in the leading singularities near two dimensions. Starting from a Grassmann functional integral representation of the strong-coupling model on the restricted

Jürgen Stein

1997-01-01

219

The application of parameter estimation to flight measurements to obtain lateral-directional stability derivatives of an augmented jet-flap STOL airplane  

NASA Technical Reports Server (NTRS)

Flight experiments with an augmented jet flap STOL aircraft provided data from which the lateral directional stability and control derivatives were calculated by applying a linear regression parameter estimation procedure. The tests, which were conducted with the jet flaps set at a 65 deg deflection, covered a large range of angles of attack and engine power settings. The effect of changing the angle of the jet thrust vector was also investigated. Test results are compared with stability derivatives that had been predicted. The roll damping derived from the tests was significantly larger than had been predicted, whereas the other derivatives were generally in agreement with the predictions. Results obtained using a maximum likelihood estimation procedure are compared with those from the linear regression solutions.

Stephenson, J. D.

1983-01-01

220

Deriving the Ginzburg-Landau parameter from heat-capacity data on magnetic superconductors with Schottky anomalies  

E-print Network

the superconducting parameters.6 Never- theless, specific-heat measurements on magnetic supercon- ductors terms, were calculated and then subtracted to improve determination of the Ginzburg- Landau parameter-temperature superconductors without advanced computation. The approximate equations allow simple calculation of the degeneracy

Hampshire, Damian

221

Derivation of potential model for LiAlO 2 by simple and effective optimization of model parameters  

Microsoft Academic Search

Interatomic potentials of LiAlO2 were constructed by a simple and effective method. In this method, the model function consists of multiple inverse polynomial functions with an exponential truncation function, and parameters in the potential model can be optimized as a solution of simultaneous linear equations. Potential energies obtained by ab initio calculation are used as fitting targets for model parameter

H. Tsuchihira; T. Oda; S. Tanaka

2009-01-01

222

On Possible Measurement of Gravitational Interaction Parameters on Board a Satellite  

E-print Network

The recently suggested SEE (Satellite Energy Exchange) method of measuring the gravitational constant $G$, possible equivalence principle violation (measured by the E\\"{o}tv\\"{o}s parameter $\\eta$) and the hypothetic 5th force parameters $\\alpha$ and $\\lambda$ on board a drag-free Earth's satellite is discussed and further developed. Various particle trajectories near a heavy ball are numerically simulated. Some basic sources of error are analysed. The $G$ measurement procedure is modelled by noise insertion to a ``true'' trajectory. It is concluded that the present knowledge of $G, \\alpha$ (for $\\lambda \\geq 1$ m) and $\\eta$ can be improved by at least two orders of magnitude.

A. D. Alexeev; K. A. Bronnikov; N. I. Kolosnitsyn; M. Yu. Konstantinov; V. N. Melnikov; A. G. Radynov

1994-03-29

223

Effect of formulation parameters and drug-polymer interactions on drug release from starch acetate matrix tablets.  

PubMed

The aim of this study was to determine, whether interactions between a drug and hydrophobic polymer matrix are present, and if so, how they affect the drug release. In addition, the most important formulation parameters, for example porosity or structure of the tablet, which have the greatest impact on drug release, were defined. Six different drug compounds, that is allopurinol, acyclovir, metronidazole, paracetamol, salicylamide and theophylline, were used in different formulations with hydrophobic starch acetate (DS 2.7) as a matrix forming polymer. Results indicate that the formulation parameters describing directly or indirectly the structure of the matrix, such as porosity, compaction force and the particle size fraction of the filler-binder, have the strongest impact on drug release. The contribution of drug property based variables is not as high as formulation parameters, but they cannot be overlooked. The contribution of water solubility and dissolution rate of the compound are obvious, but there are other significant parameters, which describe the hydrophobic and hydrophilic regions of the molecule, that also affect the drug release. This can be seen especially with the salicylamide: compound which appears to have a strong and sufficiently high hydrophobic region that interacts with starch acetate and impairs the drug release. PMID:19177516

Pajander, Jari; Korhonen, Ossi; Laamanen, Maria; Ryynänen, Eeva-Leena; Grimsey, Ian; van Veen, Bert; Ketolainen, Jarkko

2009-10-01

224

Bose-Einstein condensates with derivative and long-range interactions as set-ups for analog black holes  

NASA Astrophysics Data System (ADS)

General types of Bose-Einstein condensates are considered. The formation of black-hole analogues is examined for both short- and long-range interactions for arbitrary spatial dimensions greater than 2. The former case includes nonlinear derivative terms plus an inevitable external potential, while the latter one consists solely of gravitylike self-interactions for which intrinsic formation of analogue Schwarzschild-type background space-times is possible. The corresponding geometries are studied, and it is shown how they can be made stable. Their Hawking temperature is estimated, and it is found that in certain setups it can be significantly increased, thus providing better detectability.

Kühnel, Florian

2014-10-01

225

Interaction of hematoporphyrin derivative, light, and ionizing radiation in a rat glioma model  

SciTech Connect

The effects of hematoporphyrin derivative, light, and cobalt 60 (/sup 60/Co) irradiation were studied in a rat glioma model using an in vivo and an in vitro clonogenic assay. There was no effect on tumor growth by visible light or by a single dose of /sup 60/Co irradiation at 4 Gy or 8 Gy, whereas 16 Gy inhibited tumor growth to 40% versus the control. Hematoporphyrin derivative alone slightly stimulated growth (P less than 0.1). Light in the presence of 10 mg hematoporphyrin derivative/kg inhibited tumor growth to 32%. /sup 60/Co irradiation in the presence of hematoporphyrin derivative produced a significant tumor growth inhibition (P less than 0.02). This growth inhibition was directly related to the concentration of hematoporphyrin derivative. The addition of /sup 60/Co to light in the presence of hematoporphyrin derivative produced a greater growth inhibition than light or /sup 60/Co irradiation alone. This effect was most pronounced when light was applied 30 minutes before /sup 60/Co irradiation. Our experiments in a subcutaneous rat glioma model suggest a radiosensitizing effect of hematoporphyrin derivative. Furthermore, the photodynamic inactivation is enhanced by the addition of /sup 60/Co irradiation. These findings may be of importance in planning new treatment modalities in malignant brain tumors.

Kostron, H.; Swartz, M.R.; Miller, D.C.; Martuza, R.L.

1986-03-01

226

Photoperiod and Temperature Interact to Affect Immune Parameters in Adult Male Deer Mice  

E-print Network

(Peromyscus manicuiatus) Gregory E. Demas1 and Randy J. Nelson Department of Psychology, Behavioral manipulated in the present study to assess their effects on immune parameters in male deer mice (Peromyscus maniculatus). Animals in short days regressed their reproductive systems and also displayed significantly

Demas, Greg

227

Analysis of adjuvant effects and their interactions with variable application parameters  

Microsoft Academic Search

Herbicide performance is influenced by many variable application parameters often beyond the control of the end-user. Adjuvants can provide an effective tool to farmers to overcome or diminish the effects of adverse application conditions. Adjuvants can exert their effect either through an overall increase in activity, masking the detrimental effects of suboptimal application conditions, or by more specific effects eliminating

Per Kudsk; Solvejg Kopp Mathiassen

2007-01-01

228

Resonant interaction between a mountain wave and an environment with a vertically oscillating Scorer parameter  

NASA Astrophysics Data System (ADS)

Among the mechanisms that lead to an increase of the drag produced by atmospheric mountain waves, the resonance that occurs when the environment has a Scorer parameter profile that oscillates with height has been the object of recent interest. This resonance, which has been re-discovered only very recently, was studied by previous authors in rather limited conditions, and was claimed to be intrinsically nonlinear by comparison with results of a linear model which did not detect it. In the present study, this drag enhancement mechanism is investigated further using a linear model and numerical simulations of a mesoscale non-hydrostatic numerical model. The linear model uses a perturbation approach, where the Scorer parameter is assumed to be the sum of a constant and a term proportional to a small parameter, which varies sinusoidally in the vertical. The solution to the Taylor-Goldstein equation, which commands the behaviour of the waves, is expanded in powers of this small parameter, and the resonance that is the focus of this study is found at first order. The drag normalized by its non-hydrostatic value is calculated as a function of the wavelength and phase of the Scorer parameter oscillation. It is found, in agreement with previous results, that departures of the drag from 1 occur primarily near the parameter range where the vertical wavelength of the primary gravity waves generated is twice that of the Scorer parameter oscillation. Additionally, the drag behaves differently depending on the phase of this oscillation, displaying either a considerable increase or a decrease. For the conditions considered by previous authors, the drag is enhanced by more than 50% for a specific value of the phase. In order to reproduce this enhancement in our linear model, it is essential that friction be accounted for. In the present study, this is done in the simplest possible way, by representing friction as a Rayleigh damping. The value of the Rayleigh friction coefficient may be estimated from the numerical simulations. We speculate that the reason why this drag enhancement was not captured in previous linear calculations is because they neglected friction. From these results, it is expectable that the characteristics of the resonant waves produced in this setup, and thus of the ensuing drag enhancement, are sensitive to frictional processes in numerical models. These processes may either be associated with the closure employed to parameterize the turbulence, or with the numerical damping inherent to the discretization scheme.

Teixeira, Miguel A. C.; Argaín, José L.; Miranda, Pedro M. A.

2010-05-01

229

Interactions of cyclic and non-cyclic naphthalene diimide derivatives with different nucleic acids.  

PubMed

Recently, strategy based on stabilization of G-quadruplex telomeric DNA by small organic molecule has been realized by naphthalene diimide derivatives (NDIs). At the same time NDIs bind to DNA duplex as threading intercalators. Here we present cyclic derivative of naphthalene diimide (ligand 1) as DNA-binding ligand with ability to recognition of different structures of telomeric G-quadruplexes and ability to bis-intercalate to double-stranded helixes. The results have been compared to non-cyclic derivative (ligand 2) and revealed that preferential binding of ligands to nucleic acids strongly depends on their topology and structural features of ligands. PMID:24726302

Czerwinska, Izabella; Sato, Shinobu; Juskowiak, Bernard; Takenaka, Shigeori

2014-05-01

230

Estimation of kinetic parameters related to biochemical interactions between hydrogen peroxide and signal transduction proteins  

PubMed Central

The lack of kinetic data concerning the biological effects of reactive oxygen species is slowing down the development of the field of redox signaling. Herein, we deduced and applied equations to estimate kinetic parameters from typical redox signaling experiments. H2O2-sensing mediated by the oxidation of a protein target and the switch-off of this sensor, by being converted back to its reduced form, are the two processes for which kinetic parameters are determined. The experimental data required to apply the equations deduced is the fraction of the H2O2 sensor protein in the reduced or in the oxidized state measured in intact cells or living tissues after exposure to either endogenous or added H2O2. Either non-linear fittings that do not need transformation of the experimental data or linearized plots in which deviations from the equations are easily observed can be used. The equations were shown to be valid by fitting to them virtual time courses simulated with a kinetic model. The good agreement between the kinetic parameters estimated in these fittings and those used to simulate the virtual time courses supported the accuracy of the kinetic equations deduced. Finally, equations were successfully tested with real data taken from published experiments that describe redox signaling mediated by the oxidation of two protein tyrosine phosphatases, PTP1B and SHP-2, which are two of the few H2O2-sensing proteins with known kinetic parameters. Whereas for PTP1B estimated kinetic parameters fitted in general the present knowledge, for SHP-2 results obtained suggest that reactivity toward H2O2 as well as the rate of SHP-2 regeneration back to its reduced form are higher than previously thought. In conclusion, valuable quantitative kinetic data can be estimated from typical redox signaling experiments, thus improving our understanding about the complex processes that underlie the interplay between oxidative stress and redox signaling responses.

Brito, Paula M.; Antunes, Fernando

2014-01-01

231

Interactions between 60GHz millimeter waves and artificial biological membranes: dependence on radiation parameters  

Microsoft Academic Search

Due to the increasing interest in millimeter-wave (MMW) applications for wireless communication systems, the investigation of their potential biological effects is of utmost importance. In this paper, we report experimental results of the study of interactions between low-power radiation at 60 GHz and artificial models of biological membranes. In the first part of this study, we demonstrate an increase of

Maxim Zhadobov; Ronan Sauleau; Véronique Vié; Mohamed Himdi; L. Le Coq; D. Thouroude

2006-01-01

232

Non-Abelian Monopole in the Parameter Space of Point-like Interactions  

E-print Network

We study non-Abelian geometric phase in $\\mathscr{N} = 2$ supersymmetric quantum mechanics for a free particle on a circle with two point-like interactions at antipodal points. We show that non-Abelian Berry's connection is that of $SU(2)$ magnetic monopole discovered by Moody, Shapere and Wilczek in the context of adiabatic decoupling limit of diatomic molecule.

Satoshi Ohya

2014-06-18

233

Non-Abelian Monopole in the Parameter Space of Point-like Interactions  

E-print Network

We study non-Abelian geometric phase in $\\mathscr{N} = 2$ supersymmetric quantum mechanics for a free particle on a circle with two point-like interactions at antipodal points. We show that non-Abelian Berry's connection is that of $SU(2)$ magnetic monopole discovered by Moody, Shapere and Wilczek in the context of adiabatic decoupling limit of diatomic molecule.

Ohya, Satoshi

2014-01-01

234

Interactive initialization of heat flux parameters for numerical models using satellite temperature measurements  

NASA Technical Reports Server (NTRS)

Progress made in HCMM research, including testing the interactive minicomputer system and preparation of a paper on the analysis of regional scale soil moisture patterns, is summarized. An exhibit on remote sensing including a videotape display of HCMM images, most of them of the State College area, was prepared.

Carlson, T. N. (principal investigator)

1982-01-01

235

Accelerated expansion of an anisotropic Brans–Dicke cosmology from nonlinear derivative interaction and Gauss–Bonnet invariant  

Microsoft Academic Search

The study of Brans–Dicke cosmology has attracted considerable attention in the recent years since it explains most of the\\u000a important features of the progress of the universe. We discuss in this letter a homogeneous and anisotropic cosmological model\\u000a in the framework of Brans–Dicke theory including together a non-linear derivative interaction which appears in theory with\\u000a the Galilean shift symmetry, a

Ahmad Rami El-Nabulsi

2010-01-01

236

Accelerated expansion of an anisotropic Brans-Dicke cosmology from nonlinear derivative interaction and Gauss-Bonnet invariant  

Microsoft Academic Search

The study of Brans-Dicke cosmology has attracted considerable attention in the recent years since it explains most of the important features of the progress of the universe. We discuss in this letter a homogeneous and anisotropic cosmological model in the framework of Brans-Dicke theory including together a non-linear derivative interaction which appears in theory with the Galilean shift symmetry, a

Ahmad Rami El-Nabulsi

2010-01-01

237

Analysis of Anthrax and Plague Biowarfare Vaccine Interactions with Human Monocyte-Derived Dendritic Cells1  

Microsoft Academic Search

The anti-biowarfare anthrax and plague vaccines require repeated dosing to achieve adequate protection. To test the hypothesis that this limited immunogenicity results from the nature of vaccine interactions with the host innate immune system, we inves- tigated molecular and cellular interactions between vaccines, dendritic cells (DCs), and T cells and explored the potential for adjuvants (pertussis) to boost induction of

Anna Skowera; Esther C. de Jong; Joost H. N. Schuitemaker; Jennifer S. Allen; Simon C. Wessely; Gareth Griffiths; Martien Kapsenberg; Mark Peakman

238

Novel Peptide-Mediated Interactions Derived from High-Resolution 3Dimensional Structures  

Microsoft Academic Search

Many biological responses to intra- and extracellular stimuli are regulated through complex networks of transient protein interactions where a globular domain in one protein recognizes a linear peptide from another, creating a relatively small contact interface. These peptide stretches are often found in unstructured regions of proteins, and contain a consensus motif complementary to the interaction surface displayed by their

Amelie Stein; Patrick Aloy

2010-01-01

239

Deriving requirements for an online community interaction scheme: indications from older adults  

Microsoft Academic Search

Social media and online communication encourage social interaction but do little to strengthen community relations between people who live in the same area. The aim of this work is to develop a set of requirements, in this initial case from a group of older adults, for an online system aimed at increasing local face-to-face communication and enhancing community interaction. Eleven

David Greathead; Lynne Coventry; Budi Arief; Aad van Moorsel

2012-01-01

240

Stable Association of Presenilin Derivatives and Absence of Presenilin Interactions with APP  

Microsoft Academic Search

Mutations in two related genes,presenilin 1andpresenilin 2(PS1andPS2), cosegregate with Alzheimer's disease. PS1 and PS2 are highly homologous polytopic membrane proteins that are subject to endoproteolytic cleavagein vivo.The resulting N- and C-terminal derivatives are the preponderant PS-related species that accumulate in cultured cells and tissue. In earlier studies, we demonstrated that PS1 N- and C-terminal derivatives accumulate to 1:1 stoichiometry and

Gopal Thinakaran; Jean B. Regard; Christopher M. L. Bouton; Christie L. Harris; Donald L. Price; David R. Borchelt; Sangram S. Sisodia

1998-01-01

241

Self-Assembly of Pyridine-Modified Lipoic Acid Derivatives on Gold and Their Interaction with Thyroxine (T4)  

PubMed Central

Pyridyl derivatives of lipoic acid were prepared as ligands for the study of the interaction with thyroxine (T4). Thin self-assembled films of the ligands were prepared in 70% ethanol on gold and their interaction with T4 was studied by titration experiments in an aqueous buffer solution using Surface Plasmon Resonance (SPR). The thickness and refractive index of the ligand layers were calculated from SPR spectra recorded in two media, also allowing for surface coverage and the density of the layers to be estimated. Two ligands, a 4-pyridyl and a bis(2-hydroxyethyl) derivative of lipoic acid, were selected to investigate the feasibility for producing molecularly imprinted self-assembled layers on gold for T4. The methodology was to co-assemble T4 and the ligand onto the gold surface, elute the T4 from the layer under alkaline conditions, and study the rebinding of T4 to the layer. Multiple elution/rebinding cycles were conducted in different buffer solutions, and rebinding of T4 could be observed, with a moderate binding affinity that depended greatly on the solvent used. More optimal binding was observed in HBS buffer, and the affinity of the interaction could be slightly increased when the 4-pyridyl and bis(2-hydroxy-ethyl) derivatives of lipoic acid were combined in the imprinted layer. PMID:23389045

Albers, Willem M.; Milani, Roberto; Tappura, Kirsi; Munter, Tony; Resnati, Giuseppe; Metrangolo, Pierangelo

2013-01-01

242

Ablation parameters in KrF laser/plasma interaction: An experimental study  

NASA Astrophysics Data System (ADS)

Experimental measurements of ablation parameters in a KrF laser produced aluminum plasma are presented for the laser intensity range of 1011-1013 W/cm2. Plasma created from large focal spots shows single broad ion current pulses as compared to two groups of ions observed from small focal spots. Detailed analysis of the velocity distributions of emitted ions is carried out to understand this behavior and its effect on measurements of the ablation parameters. Scalings with laser intensity of the mass ablation rate (?˜I0.42L) and of the ablation pressure (Pa˜I0.81L) giving ?=1.5×105 g cm-2 sec-1 and Pa=5.5 Mbar at a laser intensity of 1013 W/cm2 are obtained. The results are found to be in good agreement with the predictions of a plasma ablation model based on inverse bremsstrahlung dominated absorption.

Gupta, P. D.; Tsui, Y. Y.; Popil, R.; Fedosejevs, R.; Offenberger, A. A.

1987-01-01

243

Ab Initio Calculation of Hyperfine Interaction Parameters: Recent Evolutions, Recent Examples  

Microsoft Academic Search

For some years already, ab initio calculations based on Density Functional Theory (DFT) belong to the toolbox of the field of hyperfine interaction studies.\\u000a In this paper, the standard ab initio approach is schematically sketched. New features, methods and possibilities that broke through during the past few years\\u000a are listed, and their relation to the standard approach is explained. All

Stefaan Cottenier; Veerle Vanhoof; Doru Torumba; Valerio Bellini; Mehmet Çakmak; Michel Rots

2004-01-01

244

Resolving CP violation by standard and nonstandard interactions and parameter degeneracy in neutrino oscillations  

Microsoft Academic Search

In neutrino oscillation with non-standard interactions (NSI) the system is enriched with CP violation caused by phases due\\u000a to NSI in addition to the standard lepton Kobayashi-Maskawa phase ?. In this paper we show that it is possible to disentangle\\u000a the two CP violating effects by measurement of muon neutrino appearance by a near-far two detector setting in neutrino factory

A. M. Gago; H. Minakata; H. Nunokawa; S. Uchinami; R. Zukanovich Funchal

2010-01-01

245

Numerical modeling of laser–matter interaction in the region of “low” laser parameters  

Microsoft Academic Search

The interaction of laser radiation with matter leads to the certain kinds of modelling of its surface or volume. These effects\\u000a have been demonstrated for a lot of materials, even causing the formation of new scientific and industrial domain, which is\\u000a undoubtedly laser material processing and as well as laser cleaning of artworks. Those applications lie in the so-called “low'''

J. Marczak; K. Jach; R. ?wierczy?ski

2010-01-01

246

Parameter dependence of vortex interactions on a two-dimensional plunging plate  

NASA Astrophysics Data System (ADS)

The structure and dynamics of the flow field created by a plunging flat-plate airfoil are investigated at a chord Reynolds number of 10,000 while varying plunge amplitude and Strouhal number. Digital particle image velocimetry measurements are used to characterize the shedding patterns and the interactions between the leading- and trailing-edge vortex structures (LEV and TEV), resulting in the development of a wake classification system based on the nature and timing of interactions between the leading- and trailing-edge vortices. The streamwise advancement of the LEV during a plunge cycle and its resulting interaction with the TEV is primarily dependent on reduced frequency; however, for Strouhal numbers above approximately 0.4, significant changes are observed in the formation of vortices shed from the leading and trailing edges, as well as the circulation of the leading-edge vortex. The functional form of the relationship between leading-edge vortex circulation and Strouhal number suggests that the Strouhal number dependence is more specifically a manifestation of the effective angle of attack. Comparison with low-Reynolds-number studies of plunging airfoil aerodynamics reveals a high degree of consistency and suggests applicability of the classification system beyond the range examined in the present work.

Eslam Panah, Azar; Buchholz, James H. J.

2014-03-01

247

Interaction and Localization of One-electron Orbitals in an Organic Molecule: Fictitious Parameter Analysis for Multi-physics Simulations  

E-print Network

We present a new methodology to analyze complicated multi-physics simulations by introducing a fictitious parameter. Using the method, we study quantum mechanical aspects of an organic molecule in water. The simulation is variationally constructed from the ab initio molecular orbital method and the classical statistical mechanics with the fictitious parameter representing the coupling strength between solute and solvent. We obtain a number of one-electron orbital energies of the solute molecule derived from the Hartree-Fock approximation, and eigenvalue-statistical analysis developed in the study of nonintegrable systems is applied to them. Based on the results, we analyze localization properties of the electronic wavefunctions under the influence of the solvent.

Toshiya Takami; Jun Maki; Jun-ichi Ooba; Taizo Kobayashi; Rie Nogita; Mutsumi Aoyagi

2006-11-22

248

Copolythiophene-derived colorimetric and fluorometric sensor for lysophosphatidic acid based on multipoint interactions.  

PubMed

3-Phenylthiophene-based water-soluble copolythiophenes (CPT9) were designed for colorimetric and fluorometric detection of lysophosphatidic acid (LPA) based on electrostatic interaction, hydrophobic interaction, and hydrogen bonding. Other negatively charged species gave nearly no interference, and the detection limit reached to 0.6 ?M, which is below the requisite detection limits for LPA in human plasma samples. The appealing performance of CPT9 was demonstrated to originate from the multipoint interaction-induced conformational change of conjugated backbone and weakened electron transfer effect. To our best knowledge, this is the first polythiophene based optical sensor which displays emission peak red-shift followed with fluorescence enhancement. PMID:23459452

Lan, Minhuan; Liu, Weimin; Wang, Ying; Ge, Jiechao; Wu, Jiasheng; Zhang, Hongyan; Chen, Jianhong; Zhang, Wenjun; Wang, Pengfei

2013-03-01

249

Interactive initialization of heat flux parameters for numerical models using satellite temperature measurements. [Kansas and Indiana  

NASA Technical Reports Server (NTRS)

A method for obtaining patterns of moisture availability (and net evaporation) from satellite infrared measurements employs Carlson's boundary layer model and a variety of image processing routines executed by a minicomputer. To test the method with regard to regional scale moisture analyses, two case studies were chosen because of the availability of HCMM data and because of the presence of a large horizontal gradient in antecedent precipitation and crp moisture index. Results show some correlation in both cases between antecedent precipitation and derived moisture availability. Apparently, regional-scale moisture availability patterns can be determined with some degree of fidelity but the values themselves may be useful only in the relative sense and significant to within plus or minus one category of dryness over a range of 4 or 5 categories between absolutely dry and field saturation. Preliminary results suggest that the derived moisture values correlate best with longer-term precipitation totals, suggesting that the infrared temperatures respond more sensitively to a relatively deep substrate layer.

Carlson, T. N. (principal investigator)

1982-01-01

250

I-NoLLS: A program for interactive nonlinear least-squares fitting of the parameters of physical models  

NASA Astrophysics Data System (ADS)

The I-NoLLS program is a package for carrying out interactive nonlinear least-squares fits to determine the parameters of physical or mathematical models from experimental or other data, under circumstances where automated least-squares procedures are excessively computationally expensive and the user needs interactive control to apply physical insight to the fitting process. The program was developed to facilitate the fitting of molecular potential energy surfaces (PES) to spectroscopic and scattering data, but is also applicable to a variety of other optimization problems. A range of different algorithms adapted to highly nonlinear least-squares problems may be selected. The interactive nature of the code permits rapid and flexible control over the progress of the fit. I-NoLLS is written in a modular way that allows the easy incorporation of new modules for calculating observable quantities from model parameters. The structure of the program allows straightforward parallelisation of the time-consuming property calculations. In pilot applications, I-NoLLS has been interfaced with programs for calculating bound states of Van der Waals complexes, cross sections for molecular scattering processes, and second virial coefficients of gas mixtures. Parallelisation of the property calculations has been achieved using PVM running on a cluster of workstations.

Law, Mark M.; Hutson, Jeremy M.

1997-05-01

251

Analytic derivative couplings for spin-flip configuration interaction singles and spin-flip time-dependent density functional theory.  

PubMed

We revisit the calculation of analytic derivative couplings for configuration interaction singles (CIS), and derive and implement these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code that has CIS analytic energy gradients. The additional cost of evaluating the derivative couplings is small in comparison to the cost of evaluating the gradients for the two electronic states in question. Incorporation of an exchange-correlation term provides an ad hoc extension of this formalism to time-dependent density functional theory within the Tamm-Dancoff approximation, without the need to invoke quadratic response theory or evaluate third derivatives of the exchange-correlation functional. Application to several different conical intersections in ethylene demonstrates that minimum-energy crossing points along conical seams can be located at substantially reduced cost when analytic derivative couplings are employed, as compared to use of a branching-plane updating algorithm that does not require these couplings. Application to H3 near its D(3h) geometry demonstrates that correct topology is obtained in the vicinity of a conical intersection involving a degenerate ground state. PMID:25134548

Zhang, Xing; Herbert, John M

2014-08-14

252

Relationship between lipophilicities of 1,4-dihydropyridine derivatives and pharmacokinetic interaction strengths with grapefruit juice.  

PubMed

It is well known fact that the strengths of drug interactions with grapefruit juice (GFJ) differ greatly depending on the 1,4-dihydropyridine calcium channel antagonist (DHP) used. However, there are no available data on the relationship between interactions with GFJ and its physicochemical attributes. Therefore we endeavored to study the correlation between calculated logP values, indicating lipophilicity, from chemical structures of DHPs as well as water diffusion, molecular volume, molecular polarization, molecular density, refractive index, topologic polar surface area, and calculated molar refractivity. Thirteen forms of DHP, amlodipine, azelnidipine, benidipine, cilnidipine, efonidipine, felodipine, manidipine, nicardipine, nifedipine, nimodipine, nisoldipine, nitrendipine, and pranidipine were analyzed due to clinical trials performed with GFJ and these agents. The pharmacokinetic interaction strengths were defined in common logarithmic values of increasing ratios of area under the plasma concentration-time curve (AUC) with GFJ intake compared with controls. Physicochemical properties including three categories of predicted logP values were calculated from the structures of DHPs and their estimated relationship with the interactions. As a result, the logP values indicated significant positive correlations with the interaction strengths. This finding suggests that lipophilicity is an important factor in the strengths of pharmacokinetic interactions of DHPs with GFJ intake. PMID:18176062

Uesawa, Yoshihiro; Mohri, Kiminori

2008-01-01

253

Herb drug interaction: effect of Manix(R) on pharmacokinetic parameters of pefloxacin in rat model  

PubMed Central

Objective To evaluate the effect of Manix®, the commonly used polyherbal formulation on pefloxacin pharmacokinetic parameters. Methods Microbiological assay was employed using clinical isolate of Escherichia coli samples from hospitalized patients. Results Manix® altered the bioavailability parameters of pefloxacin as thus, maximal concentration (Cmax) of pefloxacin (0.91±0.31) µg/mL occurred at time to reach maximal concentration (tmax) 4.0 h while in the group that received Manix® alongside pefloxacin Cmax was (0.22±0.08) µg/mL at tmax 1.0 h respectively. The area under curve of pefloxacin alone was (7.83±5.14) µg/h/mL while with Manix® was (2.60±0.08) µg/h/mL. There was a significant difference between Cmax, tmax and area under curve between pefloxacin alone and pefloxacin after Manix® pre-treatment (P<0.05). Conclusions The concurrent use of Manix® and pefloxacin has been found to compromise the therapeutic effectiveness of pefloxacin which could lead to poor clinical outcomes in patients. PMID:25183119

Odunke, Nduka Sunday; Eleje, Okonta; Christiana, Abba Chika; Peter, Ihekwereme Chibueze; Uchenna, Ekwedigwe; Matthew, Okonta

2014-01-01

254

Direct Interaction of Antifungal Azole-Derivatives with Calmodulin: A Possible Mechanism for Their Therapeutic Activity  

Microsoft Academic Search

Azole derivatives, such as ketoconazole and bifonazole, are well-established antifungal drugs. Recently, these compounds have been reported to have therapeutic efficacy also in inflammatory skin disorders. These is increasing evidence that calmodulin is involved in fungal infections as well as in inflammatory skin diseases. Therefore, we investigated the effects of various antifungal drugs on calmodulin activity, using calmodulin-dependent phosphodiesterase as

Lutz Hegemann; Susan M. Toso; Khosrow L Lahijani; Guy F. Webster; Jouni Uitto

1993-01-01

255

Self-assembly of pyrene derivatives on Au(111): substituent effects on intermolecular interactions.  

PubMed

The adsorption behaviour as well as the influence of bromine substituents on the formation of highly-ordered two-dimensional structures of pyrene derivatives on Au(111) are studied by a combination of scanning tunnelling microscopy (STM) and density functional theory (DFT) calculations. PMID:24905327

Pham, Tuan Anh; Song, Fei; Nguyen, Manh-Thuong; Stöhr, Meike

2014-10-21

256

Interactions of Jet Fuels with Nitrile O-Rings: Petroleum-Derived versus Synthetic Fuels  

SciTech Connect

A transition from petroleum-derived jet fuels to blends with Fischer-Tropsch (F-T) fuels, and ultimately fully synthetic hydro-isomerized F-T fuels has raised concern about the fate of plasticizers in nitrile-butadiene rubber o-rings that are contacted by the fuels as this transition occurs. The partitioning of plasticizers and fuel molecules between nitrile o-rings and petroleum-derived, synthetic, and additized-synthetic jet fuels has been measured. Thermal desorption of o-rings soaked in the various jet fuels followed by gas chromatographic analysis with a mass spectrometric detector showed many of the plasticizer and stabilizer compounds were removed from the o-rings regardless of the contact fuel. Fuel molecules were observed to migrate into the o-rings for the petroleum-derived fuel as did both the fuel and additive for a synthetic F-T jet fuel additized with benzyl alcohol, but less for the unadditized synthetic fuel. The specific compounds or classes of compounds involved in the partitioning were identified and a semiquantitative comparison of relative partitioning of the compounds of interest was made. The results provide another step forward in improving the confidence level of using additized, fuIly synthetic jet fuel in the place of petroleum-derived fueL

Gormley, R.J.; Link, D.D.; Baltrus, J.P.; Zandhuis, P.H.

2008-01-01

257

Interactions of Jet Fuels with Nitrile O-Rings: Petroleum-Derived versus Synthetic Fuels  

SciTech Connect

A transition from petroleum-derived jet fuels to blends with Fischer-Tropsch (F-T) fuels, and ultimately fully synthetic hydro-isomerized F-T fuels has raised concern about the fate of plasticizers in nitrile-butadiene rubber a-rings that are contacted by the fuels as this transition occurs. The partitioning of plasticizers and fuel molecules between nitrile a-rings and petroleum-derived, synthetic, and additized-synthetic jet fuels has been measured. Thermal desorption of o-rings soaked in the various jet fuels followed by gas chromatographic analysis with a mass spectrometric detector showed many of the plasticizer and stabilizer compounds were removed from the o-rings regardless of the contact fuel. Fuel molecules were observed to migrate into the o-rings for the petroleum-derived fuel as did both the fuel and additive for a synthetic F-T jet fuel additized with benzyl alcohol, but less for the unadditized synthetic fuel. The specific compounds or classes of compounds involved in the partitioning were identified and a semiquantitative comparison of relative partitioning of the compounds of interest was made. The results provide another step forward in improving the confidence level of using additized, fully synthetic jet fuel in the place of petroleum-derived fuel.

Gormley, R.J.; Link, D.D.; Baltrus, J.P.; Zandhuis, P.H.

2009-01-01

258

Specimen specific parameter identification of ovine lumbar intervertebral discs: On the influence of fibre-matrix and fibre-fibre shear interactions.  

PubMed

Numerical models of the intervertebral disc, which address mechanical questions commonly make use of the difference in water content between annulus and nucleus, and thus fluid and solid parts are separated. Despite this simplification, models remain complex due to the anisotropy and nonlinearity of the annulus and regional variations of the collagen fibre density. Additionally, it has been shown that cross-links make a large contribution to the stiffness of the annulus. Because of this complex composite structure, it is difficult to reproduce several sets of experimental data with one single set of material parameters. This study addresses the question to which extent the ultrastructure of the intervertebral disc should be modelled so that its moment-angle behaviour can be adequately described. Therefore, a hyperelastic constitutive law, based on continuum mechanical principles was derived, which does not only consider the anisotropy from the collagen fibres, but also interactions among the fibres and between the fibres and the ground substance. Eight ovine lumbar intervertebral discs were tested on a custom made spinal loading simulator in flexion/extension, lateral bending and axial rotation. Specimen-specific geometrical models were generated using CT images and T2 maps to distinguish between annulus fibrosus and nucleus pulposus. For the identification of the material parameters the annulus fibrosus was described with two scenarios: with and without fibre-matrix and fibre-fibre interactions. Both scenarios showed a similar behaviour on a load displacement level. Comparing model predictions to the experimental data, the mean RMS of all specimens and all load cases was 0.54±0.15° without the interaction and 0.54±0.19° when the fibre-matrix and fibre-fibre interactions were included. However, due to the increased stiffness when cross-links effects were included, this scenario showed more physiological stress-strain relations in uniaxial and biaxial stress states. Thus, the present study suggests that fibre-matrix and fibre-fibre interactions should be considered in the constitutive law when the model addresses questions concerning the stress field of the annulus fibrosus. PMID:24361932

Reutlinger, Christoph; Bürki, Alexander; Brandejsky, Vaclav; Ebert, Lars; Büchler, Philippe

2014-02-01

259

Dynamic calibration of higher eigenmode parameters of a cantilever in atomic force microscopy by using tip-surface interactions  

PubMed Central

Summary We present a theoretical framework for the dynamic calibration of the higher eigenmode parameters (stiffness and optical lever inverse responsivity) of a cantilever. The method is based on the tip–surface force reconstruction technique and does not require any prior knowledge of the eigenmode shape or the particular form of the tip–surface interaction. The calibration method proposed requires a single-point force measurement by using a multimodal drive and its accuracy is independent of the unknown physical amplitude of a higher eigenmode. PMID:25383301

Forchheimer, Daniel; Haviland, David B

2014-01-01

260

Interaction of coal-derived synthesis gas impurities with solid oxide fuel cell metallic components  

SciTech Connect

Chromium-containing iron-based alloys Crofer22 APU and SS 441 and nickel-based alloy Inconel600, all commonly used in a solid oxide fuel cell (SOFC) stack as interconnect materials, heat exchanger and gas feeding pipes, were exposed at 700-850oC to a synthetic coal gas containing ?2 ppm phosphine, arsine, sulfur and antimony. Samples were characterized by SEM/EDS and XRD to monitor the secondary phase formation. Exposure of ferritic stainless steels to P led to the formation of surface Cr-Mn-P-O and Fe-P-O compounds and increased temperatures accelerated the rate of interactions. Fewer interactions were observed after exposures to As and Sb. No sulfur containing compounds were found. Nickel-based alloy exhibited much stronger interactions with As and P in comparison with ferritic steels and the arsenic interactions were particularly strong. The difference between the iron- and nickel-based alloys is explained by the different chemistry and morphology of the scales grown on the alloy surfaces in coal gas. While P and As interactions with the metallic parts in the SOFC are likely to mitigate the nickel/zirconia anode poisoning, the other degradation mechanisms should be taken into consideration to avoid potential stack failures. Manganese spinels were found to be effective as phosphorus getters and could be used in coal gas cleanup.

Marina, Olga A.; Pederson, Larry R.; Coyle, Christopher A.; Edwards, Danny J.; Chou, Y. S.; Cramer, Carolyn N.

2010-05-28

261

Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment  

NASA Astrophysics Data System (ADS)

This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H? and the H? lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.

2012-08-01

262

A flexible, interactive software tool for fitting the parameters of neuronal models  

PubMed Central

The construction of biologically relevant neuronal models as well as model-based analysis of experimental data often requires the simultaneous fitting of multiple model parameters, so that the behavior of the model in a certain paradigm matches (as closely as possible) the corresponding output of a real neuron according to some predefined criterion. Although the task of model optimization is often computationally hard, and the quality of the results depends heavily on technical issues such as the appropriate choice (and implementation) of cost functions and optimization algorithms, no existing program provides access to the best available methods while also guiding the user through the process effectively. Our software, called Optimizer, implements a modular and extensible framework for the optimization of neuronal models, and also features a graphical interface which makes it easy for even non-expert users to handle many commonly occurring scenarios. Meanwhile, educated users can extend the capabilities of the program and customize it according to their needs with relatively little effort. Optimizer has been developed in Python, takes advantage of open-source Python modules for nonlinear optimization, and interfaces directly with the NEURON simulator to run the models. Other simulators are supported through an external interface. We have tested the program on several different types of problems of varying complexity, using different model classes. As targets, we used simulated traces from the same or a more complex model class, as well as experimental data. We successfully used Optimizer to determine passive parameters and conductance densities in compartmental models, and to fit simple (adaptive exponential integrate-and-fire) neuronal models to complex biological data. Our detailed comparisons show that Optimizer can handle a wider range of problems, and delivers equally good or better performance than any other existing neuronal model fitting tool. PMID:25071540

Friedrich, Peter; Vella, Michael; Gulyas, Attila I.; Freund, Tamas F.; Kali, Szabolcs

2014-01-01

263

Quantifying and Reducing Biases in Satellite Derived Ice Cloud Optical Thickness and Ice Effective Diameter by Simultaneous Retrievals of Ice Asymmetry Parameter  

NASA Astrophysics Data System (ADS)

The ice cloud optical thickness (COT) and the ice crystal effective diameter (Deff), defined as one-and-one-half times the bulk ice volume over the bulk ice projected area, are fundamental radiative properties of ice clouds and provide valuable constraints for cloud model simulations. These parameters can be retrieved from satellite, in situ or ground-based measurements, although COT and Deff derived from such sensors are known to differ significantly amongst each other and biases need to be better quantified. Here we focus on COT and Deff at cloud top derived from satellite measurements in the visible and shortwave infrared. For such retrievals, the leading source of uncertainty is related to the asymmetry parameter of the ice optical model assumed in the retrieval algorithm. We first quantify the biases in retrieved COT and Deff as a function of bias in assumed asymmetry parameter. We then present a method to retrieve ice cloud asymmetry parameter from multi-directional polarization measurements, which allows for subsequent retrievals of COT and Deff that are not biased by a preselected ice optical model. This method is applied to combined measurements of the POLDER and MODIS satellite instruments over deep convection observed during the TWP-ICE campaign. We show that retrieved ice crystal asymmetry parameter and Deff vary systematically with cloud-top temperature, but even more so with changes of monsoon activity. Using both TWP-ICE and global measurements, we show that our retrieved COT values are significantly smaller than current operational MODIS collection 5 retrievals, because our retrieved asymmetry parameters are systematically smaller than those assumed in the operational retrievals. Moreover, the retrieved Deff values are generally 20-50% larger than operational MODIS retrievals and show a significantly wider range. Based on these results, we note expected improvements and limitations of upcoming MODIS collection 6 retrievals. Finally, we briefly discuss the use of our retrievals for evaluating cloud-resolving model simulations.

van Diedenhoven, B.; Fridlind, A. M.; Ackerman, A. S.; Cairns, B.

2013-12-01

264

Derivative expansion for the boundary interaction terms in the Casimir effect: Generalized {delta} potentials  

SciTech Connect

We calculate the Casimir energy for scalar fields in interaction with finite-width mirrors, described by nonlocal interaction terms. These terms, which include quantum effects due to the matter fields inside the mirrors, are approximated by means of a local expansion procedure. As a result of this expansion, an effective theory for the vacuum field emerges, which can be written in terms of generalized {delta} potentials. We compute explicitly the Casimir energy for these potentials and show that, for some particular cases, it is possible to reinterpret them as imposing imperfect Dirichlet boundary conditions.

Fosco, C. D. [Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, R8402AGP Bariloche (Argentina); Lombardo, F. C.; Mazzitelli, F. D. [Departamento de Fisica Juan Jose Giambiagi, FCEyN UBA, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina)

2009-10-15

265

An open-pore structure of the mechanosensitive channel MscL derived by determining transmembrane domain interactions upon gating  

PubMed Central

Mechanosensation, the ability to detect mechanical forces, underlies the senses of hearing, balance, touch, and pain, as well as renal and cardiovascular regulation. Although the sensors are thought to be channels, relatively little is known about eukaryotic mechanosensitive channels or their molecular mechanisms. Thus, because of its tractable nature, a bacterial mechanosensitive channel that serves as an in vivo osmotic “emergency release valve,” MscL, has become a paradigm of how a mechanosensitive channel can sense and respond to membrane tension. Here, we have determined the structural rearrangements and interactions between transmembrane domains of MscL that occur upon gating. We utilize an electrostatic repulsion test: If two residues approach upon gating we predicted that substituting like-charges at those sites would inhibit gating. The in vivo growth and viability and in vitro vesicular flux and electrophysiological data all support the hypothesis that residues G26 and I92 directly interact upon gating. The resulting model predicted other interacting residues. One of these sets, V23 and I96, was confirmed to truly interact upon gating by disulfide trapping as well as the electrostatic repulsion test. Together, the data strongly suggest a model for structural transitions and residue-residue proximities that occur upon MscL gating.—Li, Y., Wray, R., Eaton, C., Blount, P. An open-pore structure of the mechanosensitive channel MscL derived by determining transmembrane domain interactions upon gating. PMID:19261722

Li, Yuezhou; Wray, Robin; Eaton, Christina; Blount, Paul

2009-01-01

266

Constraints on Spin State and Hapke Parameters of Asteroid 4769 Castalia Using Lightcurves and a Radar-Derived Shape Model  

Microsoft Academic Search

A 167-parameter, 3-D shape model of the Earth-crossing asteroid Castalia, obtained from inversion of delay-Doppler images (Hudson and Ostro, 1994, Science 263, 940-943) constrained the object's pole to lie on a cone of half angle 55 +\\/- 10 deg centered on the radar line of sight (right ascension 0.3 hr, declination 25.4 deg) at the time of observations (Aug. 22,

R. Scott Hudson; Steven J. Ostro; Alan W. Harris

1997-01-01

267

Constraints on Spin State and Hapke Parameters of Asteroid 4769 Castalia Using Lightcurves and a Radar-Derived Shape Model  

Microsoft Academic Search

A 167-parameter, 3-D shape model of the Earth-crossing asteroid Castalia, obtained from inversion of delay-Doppler images (Hudson and Ostro, 1994,Science263,940–943) constrained the object's pole to lie on a cone of half angle 55 ± 10° centered on the radar line of sight (right ascension 0.3 hr, declination 25.4°) at the time of observations (Aug. 22, 1989) but could not constrain

R. Scott Hudson; Steven J. Ostro; Alan W. Harris

1997-01-01

268

Astrocyte-Derived Tissue Transglutaminase Interacts with Fibronectin: A Role in Astrocyte Adhesion and Migration?  

Microsoft Academic Search

An important neuropathological feature of neuroinflammatory processes that occur during e.g. Multiple Sclerosis (MS) is the formation of an astroglial scar. Astroglial scar formation is facilitated by the interaction between astrocytes and extracellular matrix proteins (ECM) such as fibronectin. Since there is evidence indicating that glial scars strongly inhibit both axon growth and (re)myelination in brain lesions, it is important

Miriam E. van Strien; John J. P. Brevé; Silvina Fratantoni; Marco W. J. Schreurs; John G. J. M. Bol; Cornelis A. M. Jongenelen; Benjamin Drukarch; Anne-Marie van Dam; Colin Combs

2011-01-01

269

Fractional-derivative viscoelastic model of the shock interaction of a rigid body with a plate  

Microsoft Academic Search

The impact of a rigid body upon an elastic isotropic plate is investigated for the case when the equations of motion take\\u000a rotary inertia and shear deformation into account. The impactor is considered as a mass point, and the contact between it\\u000a and the plate is established through a buffer involving a linear-spring–fractional-derivative dashpot combination, i.e., the\\u000a viscoelastic features of

Yu. A. Rossikhin; M. V. Shitikova

2008-01-01

270

Assessing the relationship between urban parameters and the LST derived by satellite and aerial imageries in a GIS environment: the case of Bari (Italy).  

NASA Astrophysics Data System (ADS)

The use of thermal remote sensing to estimate the phenomenon of urban heat islands (UHI) and development of climate anomalies in urban context represents a consolidated approach. In the current scientific literature a widespread case studies were focused on the estimation of the relationship between features related to the urban environment and the Land Surface Temperatures (LST). The latter is a basic starting observation in the investigation on the UHI phenomenon . However, the evaluation of these relationships is rather difficult. This is due to deficiencies in the detailed knowledge of parameters able to describe geometric and qualitative properties of land covers. These properties are very often not repeatable and not easily transferable in other contexts. In addition, many of the relevant parameters are difficult to be determined at the required spatial resolution and analyses are affected by a lack in the amount of quantitative parameters used. In addition to the LST, several useful indicators are introduced by the literature in the investigation of such phenomena. The objective of this work is to study the relationship between the LST and a set of variables that characterize the anthropic and natural domains of the urban areas, such as urban morphology, the Normalized Differenced Vegetation Index (NDVI), the Sky View Factor (SVF) and other morphometric parameters implemented within a GIS environment. The study case is the city of Bari (Southern Italy) where several recognizable morphologies exhibit a different thermal behavior. The LST parameter was derived from a collection of satellite ASTER images collected within a period spanning from July 2001 and July 2006, whereas aerial thermal imageries were acquired on September 2013. The basic data used for the determination of the descriptive parameters of the urban environmental are derived from digital maps(Geographic Information System of the Apulia Region), Digital Elevation Model and Land Use. The analysis of satellite and aerial thermal images available at different spatial resolutions and related to varying epochs helped to highlight variables which seem more appropriate to define the relationships between the LST and the urban features at different scales of analysis. This derived relationship far from linearity and more complex rules are needed to explain the mutual dependency between the parameters. A multivariate statistical analysis was therefore used to adequately represent both the mutual relationships among the explanatory variables and between the explanatory variables and the LST.

Caprioli, Mauro; Ceppi, Claudia; Falchi, Ugo; Mancini, Francesco; Scarano, Mario

2014-05-01

271

Precision measurements of the Co60 ?-asymmetry parameter in search for tensor currents in weak interactions  

NASA Astrophysics Data System (ADS)

The ?-asymmetry parameter à for the Gamow-Teller decay of Co60 was measured by polarizing the radioactive nuclei with the brute-force low-temperature nuclear-orientation method. The Co60 activity was cooled down to milliKelvin temperatures in a He3-He4 dilution refrigerator in an external 13-T magnetic field. The ? particles were observed by a 500-?m-thick Si PIN diode operating at a temperature of about 10 K in a magnetic field of 0.6 T. Extensive geant4 Monte Carlo simulations were performed to gain control over the systematic effects. Our result, Ã=-1.014(12)stat(16)syst, is in agreement with the standard-model value of -0.987(9), which includes recoil-order corrections that were addressed for the first time for this isotope. Further, it enables limits to be placed on possible tensor-type charged weak currents, as well as other physics beyond the standard model.

Wauters, F.; Kraev, I.; Zákoucký, D.; Beck, M.; Breitenfeldt, M.; de Leebeeck, V.; Golovko, V. V.; Kozlov, V. Yu.; Phalet, T.; Roccia, S.; Soti, G.; Tandecki, M.; Towner, I. S.; Traykov, E.; van Gorp, S.; Severijns, N.

2010-11-01

272

Concentration dependence of the Flory-Huggins interaction parameter in aqueous solutions of capped PEO chains  

E-print Network

The dependence on volume fraction $\\varphi$ of the Flory-Huggins $\\chi_{\\mathrm{wp}}\\left(\\varphi\\right)$ describing the free energy of mixing of polymers in water is obtained by exploiting the connection of $\\chi_{\\mathrm{wp}}\\left(\\varphi\\right)$ to the chemical potential of the water, for which quasi-chemical theory is satisfactory. We test this theoretical approach with simulation data for aqueous solutions of capped PEO oligomers. For CH$_3$(CH$_2$-O-CH$_2$)$_m$CH$_3$ ($m$=11), $\\chi_{\\mathrm{wp}}\\left(\\varphi\\right)$ depends strongly on $\\varphi$, consistent with experiment. These results identify coexisting water-rich and water-poor solutions at $T$ = 300K and $p$ = 1atm. Direct observation of the coexistence of these two solutions on simulation time scales supports that prediction for the system studied. This approach directly provides the osmotic pressures. The osmotic second virial coefficient for these chains is positive, reflecting repulsive interactions between the chains in the water, a good solvent for these chains.

M. I. Chaudhari; L. R. Pratt; M. E. Paulaitis

2014-10-05

273

Concentration dependence of the Flory-Huggins interaction parameter in aqueous solutions of capped PEO chains  

E-print Network

The dependence on volume fraction $\\varphi$ of the Flory-Huggins $\\chi_{\\mathrm{wp}}\\left(\\varphi\\right)$ describing the free energy of mixing of polymers in water is obtained by exploiting the connection of $\\chi_{\\mathrm{wp}}\\left(\\varphi\\right)$ to the chemical potential of the water, for which quasi-chemical theory is satisfactory. We test this theoretical approach with simulation data for aqueous solutions of capped PEO oligomers. For CH$_3$(CH$_2$-O-CH$_2$)$_m$CH$_3$ ($m$=11), $\\chi_{\\mathrm{wp}}\\left(\\varphi\\right)$ depends strongly on $\\varphi$, consistent with experiment. These results identify coexisting water-rich and water-poor solutions at $T$ = 300K and $p$ = 1atm. Direct observation of the coexistence of these two solutions on simulation time scales supports that prediction for the system studied. This approach directly provides the osmotic pressures. The osmotic second virial coefficient for these chains is positive, reflecting repulsive interactions between the chains in the water, a good sol...

Chaudhari, M I; Paulaitis, M E

2014-01-01

274

An Interactive Tool for Analysis and Optimization of Texture Parameters in Photorealistic Virtual 3d Models  

NASA Astrophysics Data System (ADS)

Texture mapping is a common method for combining surface geometry with image data, with the resulting photorealistic 3D models being suitable not only for visualization purposes but also for interpretation and spatiameasurement, in many application fields, such as cultural heritage and the earth sciences. When acquiring images for creation of photorealistic models, it is usual to collect more data than is finally necessary for the texturing process. Images may be collected from multiple locations, sometimes with different cameras or lens configurations and large amounts of overlap may exist. Consequently, much redundancy may be present, requiring sorting to choose the most suitable images to texture the model triangles. This paper presents a framework for visualization and analysis of the geometric relations between triangles of the terrain model and covering image sets. The application provides decision support for selection of an image subset optimized for 3D model texturing purposes, for non-specialists. It aims to improve the communication of geometrical dependencies between model triangles and the available digital images, through the use of static and interactive information visualization methods. The tool was used for computer-aided selection of image subsets optimized for texturing of 3D geological outcrop models. The resulting textured models were of high quality and with a minimum of missing texture, and the time spent in time-consuming reprocessing was reduced. Anecdotal evidence indicated that an increased user confidence in the final textured model quality and completeness makes the framework highly beneficial.

Sima, A. A.; Buckley, S. J.; Viola, I.

2012-07-01

275

TRADES: a new software to derive orbital parameters from observed Transit Times and Radial Velocities. Revisiting Kepler-11 and Kepler-9  

E-print Network

Aims. With the purpose of determining the orbital parameters of exoplanetary systems from observational data, we have developed a software, named TRADES (TRAnsits and Dynamics of Exoplanetary Systems) to simultaneously fit observed radial velocities and transit times data. Methods. We implemented a dynamical simulator for N-body system which also fits the available data during the orbital integration and determines the best combination of the orbital parameters using grid search, $\\chi^2$ minimization, genetic algorithms, particle swarm optimization, and bootstrap analysis. Results. To validate TRADES, we tested the code on a synthetic three-body system and on two real systems discovered by the Kepler mission: Kepler-9 and Kepler-11. These systems are good benchmarks to test multiple exoplanet systems showing transit time variations (TTVs) due to the gravitational interaction among planets. We have found orbital parameters of Kepler-11 planets in good agreement with the values proposed in the discovery paper ...

Borsato, Luca; Nascimbeni, Valerio; Piotto, Giampaolo; Granata, Valentina; Bedin, Luigi Rolly; Malavolta, Luca

2014-01-01

276

Improved CD uniformity as a function of developer chemistry and process parameters derived from a statistically designed experiment  

NASA Astrophysics Data System (ADS)

A series of experiments was run to determine the chemical and process effects on CD uniformity for Dynachem's new dyed photoresist, NOVA 2050 AR, when developed with metal ion free and metal ion type developers. The matrix of experiments included variations in spray time and puddle time, but with the constraint that all experiments had the same total time for spray and puddle times. In order to do this type of matrix it was necessary to make an unusual use of a mixture model to devise the experimental design. The design was devised to look at the effects of one-puddle, twopuddle, three-puddle and all-spray processes. Also, the effect of using either metal ion free or metal type developers was examined by running the matrix with Dynalith EPD-85 and DE-3 (0.5%) as respective examples of the two developer types. Before beginning the above matrix the baseline parameters for nozzle position, puddle time, spray time, spray speed, pre-wet time, spray pressure and spray time were determined via a Plackett- Burinan design of experiments. These three studies when compiled and analyzed with the statistical software package, RS-l, served to separate the effects of process parameters and developer type according to their effect on CD uniformity. These results suggest that three-puddle metal ion free develop processes were superior. Graphs will be shown that illustrate which parameters are the most influential concerning CD uniformity. A mathematical model will be presented that will allow the calculation of the standard deviation for CD uniformity with 95% confidence for any given set of spray and puddle times. These data and models will thereby give guidance to the process engineer how to best use developer type and process in order to obtain the best CD uniformity for a 1.0 micron process.

Christensen, Lorna D.; Bell, Ken L.; Acuna, Nadine A.

1990-06-01

277

Exploring medical diagnostic performance using interactive, multi-parameter sourced receiver operating characteristic scatter plots.  

PubMed

Determining diagnostic criteria for specific disorders is often a tedious task that involves determining optimal diagnostic thresholds for symptoms and biomarkers using receiver-operating characteristic (ROC) statistics. To help this endeavor, we developed softROC, a user-friendly graphic-based tool that lets users visually explore possible ROC tradeoffs. The software requires MATLAB installation and an Excel file containing threshold symptoms/biological measures, with corresponding gold standard diagnoses for a set of patients. The software scans the input file for diagnostic and symptom/biomarkers columns, and populates the graphical-user-interface (GUI). Users select symptoms/biomarkers of interest using Boolean algebra as potential inputs to create diagnostic criteria outputs. The software evaluates subtests across the user-established range of cut-points and compares them to a gold standard in order to generate ROC and quality ROC scatter plots. These plots can be examined interactively to find optimal cut-points of interest for a given application (e.g. sensitivity versus specificity needs). Split-set validation can also be used to set up criteria and validate these in independent samples. Bootstrapping is used to produce confidence intervals. Additional statistics and measures are provided, such as the area under the ROC curve (AUC). As a testing set, softROC is used to investigate nocturnal polysomnogram measures as diagnostic features for narcolepsy. All measures can be outputted to a text file for offline analysis. The softROC toolbox, with clinical training data and tutorial instruction manual, is provided as supplementary material and can be obtained online at http://www.stanford.edu/~hyatt4/software/softroc or from the open source repository at http://www.github.com/informaton/softroc. PMID:24561350

Moore, Hyatt E; Andlauer, Olivier; Simon, Noah; Mignot, Emmanuel

2014-04-01

278

Relativistic effects in the intermolecular interaction-induced nuclear magnetic resonance parameters of xenon dimer  

NASA Astrophysics Data System (ADS)

Relativistic effects on the Xe129 nuclear magnetic resonance shielding and Xe131 nuclear quadrupole coupling (NQC) tensors are examined in the weakly bound Xe2 system at different levels of theory including the relativistic four-component Dirac-Hartree-Fock (DHF) method. The intermolecular interaction-induced binary chemical shift ?, the anisotropy of the shielding tensor ??, and the NQC constant along the internuclear axis ? ? are calculated as a function of the internuclear distance. DHF shielding calculations are carried out using gauge-including atomic orbitals. For comparison, the full leading-order one-electron Breit-Pauli perturbation theory (BPPT) is applied using a common gauge origin. Electron correlation effects are studied at the nonrelativistic (NR) coupled-cluster singles and doubles with perturbational triples [CCSD(T)] level of theory. The fully relativistic second-order Møller-Plesset many-body perturbation (DMP2) theory is used to examine the cross coupling between correlation and relativity on NQC. The same is investigated for ? and ?? by BPPT with a density functional theory model. A semiquantitative agreement between the BPPT and DHF binary property curves is obtained for ? and ?? in Xe2. For these properties, the currently most complete theoretical description is obtained by a piecewise approximation where the uncorrelated relativistic DHF results obtained close to the basis-set limit are corrected, on the one hand, for NR correlation effects and, on the other hand, for the BPPT-based cross coupling of relativity and correlation. For ? ?, the fully relativistic DMP2 results obtain a correction for NR correlation effects beyond MP2. The computed temperature dependence of the second virial coefficient of the Xe129 nuclear shielding is compared to experiment in Xe gas. Our best results, obtained with the piecewise approximation for the binary chemical shift combined with the previously published state of the art theoretical potential energy curve for Xe2, are in excellent agreement with the experiment for the first time.

Hanni, Matti; Lantto, Perttu; Iliaš, Miroslav; Jensen, Hans Jørgen Aagaard; Vaara, Juha

2007-10-01

279

Renormalization group theory for fermions and order parameter fluctuations in interacting Fermi systems  

NASA Astrophysics Data System (ADS)

The dominant mode of coupled ocean-atmosphere variability in the Tropical Atlantic, the Atlantic Meridional Mode (AMM), responds strongly to seasonally dependent remote forcing. Previous studies have focused on AMM during boreal spring, when it is readily excited by ENSO and NAO forcing. However, relatively little is known about AMM variability during boreal fall, when it strongly regulates Atlantic hurricane activity and thus commands important societal impacts. A recent finding using a linear inverse model (LIM) of near-global SST anomalies suggests that the boreal fall AMM is forced by extratropical Atlantic SST anomalies and shows remarkable predictability with lead times approaching one year. To investigate the validity and mechanism of the LIM, a set of ensemble simulations are designed using an AGCM coupled to a slab-ocean. By initializing the GCM with LIM-derived SST anomalies, the main result of this research is the confirmation of the LIM result using an alternate physical framework. Excitation of the AMM is found to involve at least two processes: one is the thermodynamic, wind-evaporation-SST (WES) feedback, and the other is a low-cloud/SST feedback. The WES feedback is found to amplify the AMM-like response by a factor of three compared to when it is absent. However, SST anomalies are still found in the tropics when the WES feedback is suppressed. Meanwhile, the low-cloud-SST feedback is found to be locally important in the north tropical Atlantic stratocumulus region during boreal summer, but is unlikely to affect the large-scale AMM-like response. Additionally, we find that the GCM response depends strongly on the season of forcing (consistent with the LIM and some past studies), and also exhibits modest non-linearity initially, but progresses towards a more linear response later in the simulation. Another notable conclusion is that oceanic dynamics are not needed to explain the LIM result, as can be partly expected from the relatively short time-scales that are considered. This manuscript focuses on a mechanistic diagnosis of the GCM result, highlighting relevance to previous, similar studies, as well as offering several avenues for future research.

Smirnov, Dimitry

280

Surface functionalization and electronic interactions of ZnO nanorods with a porphyrin derivative.  

PubMed

To optimize electron transfer and optoelectronic properties in nanoparticulate thin films for electronics we show the surface functionalization of ZnO nanorods by means of replacing surface active 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (TODA) by a redoxactive organic component, that is, 5,10,15,20-(phenoxyacetat)-porphyrin bearing four carboxylic acids as possible ZnO anchors. Microscopy-transmission electron microscopy-and spectroscopy-optical spectroscopy-verifies the successful and homogenous integration of the porphyrin onto the surface of ZnO nanorods, a process that is facilitated by the four anchoring groups. Photophysical investigations based on emission and absorption spectroscopy prompt to distinct electronic interactions between ZnO nanorods and the porphyrins. Consequently, we performed further photophysical studies flanked by pulse radiolysis assays to corroborate the nature of the electronic interactions. PMID:24665864

Klaumünzer, Martin; Kahnt, Axel; Burger, Alexandra; Ma?kovi?, Mirza; Münzel, Corinna; Srikantharajah, Rubitha; Spiecker, Erdmann; Hirsch, Andreas; Peukert, Wolfgang; Guldi, Dirk M

2014-05-14

281

A robotic crawler exploiting directional frictional interactions: experiments, numerics, and derivation of a reduced model  

E-print Network

We present experimental and numerical results for a model crawler which is able to extract net positional changes from reciprocal shape changes, i.e. 'breathing-like' deformations, thanks to directional, frictional interactions with a textured solid substrate, mediated by flexible inclined feet. We also present a simple reduced model that captures the essential features of the kinematics and energetics of the gait, and compare its predictions with the results from experiments and from numerical simulations.

Giovanni Noselli; Antonio DeSimone

2014-08-26

282

An ecofriendly synthesis and DNA binding interaction study of some pyrazolo [1,5-a]pyrimidines derivatives.  

PubMed

The DNA molecule is a target for plethora of anticancer and antiviral drugs that forms covalent and non-covalent adducts with major or minor groove of DNA. In present study we synthesized series of novel Pyrazolo [1,5-a]pyrimidine derivatives. The newly synthesized compounds were characterized by elemental analysis, IR, (1)H NMR, and mass spectral data. The selected compounds were studied for interaction with Calf thymus DNA (CT-DNA) using electronic spectra, viscosity measurement and thermal denaturation studies. Further, molecular interactions were revealed for compound IIIa and IVa by computational methodologies. The preferred mode of ligand binding with double helical DNA as well as preferable DNA groove were explored by molecular docking in different DNA models. PMID:23122866

Chobe, Santosh S; Dawane, Bhaskar S; Tumbi, Khaled M; Nandekar, Prajwal P; Sangamwar, Abhay T

2012-12-15

283

Derivation of an interaction/regulation network describing pluripotency in human.  

PubMed

Identification of the key genes/proteins of pluripotency and their interrelationships is an important step in understanding the induction and maintenance of pluripotency. Experimental approaches have accumulated large amounts of interaction/regulation data in mouse. We investigate how far such information can be transferred to human, the species of maximum interest, for which experimental data are much more limited. To address this issue, we mapped an existing mouse pluripotency network (the PluriNetWork) to human. We transferred interaction and regulation links between genes/proteins from mouse to human on the basis of orthologous relationship of the genes/proteins (called interolog mapping). To reduce the number of false positives, we used four different methods: phylogenetic profiling, Gene Ontology semantic similarity, gene co-expression, and RNA interference (RNAi) data. The methods and the resulting networks were evaluated by a novel approach using the information about the genes known to be involved in pluripotency from the literature. The RNAi method proved best for filtering out unlikely interactions, so it was used to construct the final human pluripotency network. The RNAi data are based on human embryonic stem cells (hESCs) that are generally considered to be in a (primed) epiblast stem cell state. Therefore, we assume that the final human network may reflect the (primed) epiblast stem cell state more closely, while the mouse network reflects the (unprimed/naïve) embryonic stem cell state more closely. PMID:22548825

Som, Anup; Luštrek, Mitja; Singh, Nitesh Kumar; Fuellen, Georg

2012-07-10

284

Interactions of Anopheles gambiae Odorant-binding Proteins with a Human-derived Repellent  

PubMed Central

The Anopheles gambiae mosquito, which is the vector for Plasmodium falciparum malaria, uses a series of olfactory cues emanating from human sweat to select humans as their source for a blood meal. Perception of these odors within the mosquito olfactory system involves the interplay of odorant-binding proteins (OBPs) and odorant receptors and disrupting the normal responses to those odorants that guide mosquito-human interactions represents an attractive approach to prevent the transmission of malaria. Previously, it has been shown that DEET targets multiple components of the olfactory system, including OBPs and odorant receptors. Here, we present the crystal structure of A. gambiae OBP1 (OBP1) in the complex it forms with a natural repellent 6-methyl-5-heptene-2-one (6-MH). We find that 6-MH binds to OBP1 at exactly the same site as DEET. However, key interactions with a highly conserved water molecule that are proposed to be important for DEET binding are not involved in binding of 6-MH. We show that 6-MH and DEET can compete for the binding of attractive odorants and in doing so disrupt the interaction that OBP1 makes with OBP4. We further show that 6-MH and DEET can bind simultaneously to OBPs with other ligands. These results suggest that the successful discovery of novel reagents targeting OBP function requires knowledge about the specific mechanism of binding to the OBP rather than their binding affinity. PMID:23261834

Murphy, Emma J.; Booth, Jamie C.; Davrazou, Foteini; Port, Alex M.; Jones, David N. M.

2013-01-01

285

OPACOS: OVRO POST-AGB CO (1-0) EMISSION SURVEY. I. DATA AND DERIVED NEBULAR PARAMETERS  

SciTech Connect

We have performed interferometric observations of the {sup 12}CO (J = 1-0) emission in a sample of 27 objects spanning different evolutionary stages from the late asymptotic giant branch (late-AGB), through the post-AGB (pAGB) phase, and to the planetary nebula (PN) stage, but dominated by pAGB objects and young PNs ({>=}81%). In this paper (the first in a series) we present our maps and main nebular properties derived for the whole sample. Observations were performed with the Caltech Millimeter Array at the Owens Valley Radio Observatory. The angular resolution obtained in our survey ranges between 2.''3 and 10.''7. The {sup 13}CO and C{sup 18}O (J = 1-0) transitions as well as the 2.6 mm continuum emission have also been observed in several objects. The detection statistics in the {sup 12}CO, {sup 13}CO, C{sup 18}O transitions and 2.6 mm continuum are 89%, 83%, 0%, and 37%, respectively. We report first detections of {sup 12}CO (J = 1-0) emission in 13 targets and confirm emission from several previous marginal detections. The molecular envelope probed by {sup 12}CO (J = 1-0) emission is extended for 18 (out of 24) sources; envelope asymmetries and/or velocity gradients are found in most extended objects. Our data have been used to derive accurate target coordinates and systemic velocities and to characterize the envelope size, morphology, and kinematics. We also provide an estimate of the total molecular mass and the fraction of it contained in fast flows, lower limits to the linear momentum and to the isotopic {sup 12}C/{sup 13}C ratio, as well as the AGB mass-loss rate and timescale for sources with extended CO emission.

Sanchez Contreras, C. [Centro de Astrobiologia, INTA-CSIC, E-28691 Villanueva de la Canada, Madrid (Spain); Sahai, R. [Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109 (United States)

2012-11-15

286

Molecular interaction study of flavonoid derivative 3d with human serum albumin using multispectroscopic and molecular modeling approach.  

PubMed

Human serum albumin (HSA) has been developed as a model protein to study drug-protein interaction. In the present work, the interaction between our synthesized flavonoid derivative 3d (possessing potent antitumor activity against HepG2 cells) and HSA was investigated using fluorescence spectroscopy, circular dichroism spectroscopy, UV-vis spectroscopy and molecular modeling approach. Fluorescence spectroscopy showed that the fluorescence of HSA can be quenched remarkably by 3d under physiological condition with a slight shift of maximum fluorescence emission bands from 360nm to 363nm. Calculated results from Stern-Volmer equation and modified Stern-Volmer equation indicated that the fluorescence was quenched by static quenching processing with association constant 5.26±0.04×10(4)L mol(-1) at 298K. After comprehensive consideration of the free energy change ?G, enthalpy change ?H and entropy change ?S, electrostatic interactions were confirmed as the main factor that participate in stabilizing the 3d-HSA complex. Both dichroism spectroscopy and UV-vis spectroscopy indicated conformational change of HSA after binding to 3d. Moreover, the structure of HSA was loosened and the percentage of ?-helix decreased with increasing concentration of 3d. Molecular modeling results demonstrated that 3d could bind to HSA well into subdomain IIA, which is related to its capability of deposition and delivery. Three cation-? interactions and three hydrogen bonds occurred between 3d and amino acid residuals ARG218, ARG222 and LYS199. In conclusion, flavonoid derivative 3d can bind to HSA with noncovalent bond in a relatively stable way, so it can be delivered by HSA in a circulatory system. PMID:24881541

Wei, Juntong; Jin, Feng; Wu, Qin; Jiang, Yuyang; Gao, Dan; Liu, Hongxia

2014-08-01

287

Inhibition of human aldehyde oxidase activity by diet-derived constituents: structural influence, enzyme-ligand interactions, and clinical relevance.  

PubMed

The mechanistic understanding of interactions between diet-derived substances and conventional medications in humans is nascent. Most investigations have examined cytochrome P450-mediated interactions. Interactions mediated by other phase I enzymes are understudied. Aldehyde oxidase (AO) is a phase I hydroxylase that is gaining recognition in drug design and development programs. Taken together, a panel of structurally diverse phytoconstituents (n = 24) was screened for inhibitors of the AO-mediated oxidation of the probe substrate O(6)-benzylguanine. Based on the estimated IC50 (<100 ?M), 17 constituents were advanced for Ki determination. Three constituents were described best by a competitive inhibition model, whereas 14 constituents were described best by a mixed-mode model. The latter model consists of two Ki terms, Kis and Kii, which ranged from 0.26-73 and 0.80-120 ?M, respectively. Molecular modeling was used to glean mechanistic insight into AO inhibition. Docking studies indicated that the tested constituents bound within the AO active site and elucidated key enzyme-inhibitor interactions. Quantitative structure-activity relationship modeling identified three structural descriptors that correlated with inhibition potency (r(2) = 0.85), providing a framework for developing in silico models to predict the AO inhibitory activity of a xenobiotic based solely on chemical structure. Finally, a simple static model was used to assess potential clinically relevant AO-mediated dietary substance-drug interactions. Epicatechin gallate and epigallocatechin gallate, prominent constituents in green tea, were predicted to have moderate to high risk. Further characterization of this uncharted type of interaction is warranted, including dynamic modeling and, potentially, clinical evaluation. PMID:25326286

Barr, John T; Jones, Jeffrey P; Oberlies, Nicholas H; Paine, Mary F

2015-01-01

288

User's manual for interactive LINEAR: A FORTRAN program to derive linear aircraft models  

NASA Technical Reports Server (NTRS)

An interactive FORTRAN program that provides the user with a powerful and flexible tool for the linearization of aircraft aerodynamic models is documented in this report. The program LINEAR numerically determines a linear system model using nonlinear equations of motion and a user-supplied linear or nonlinear aerodynamic model. The nonlinear equations of motion used are six-degree-of-freedom equations with stationary atmosphere and flat, nonrotating earth assumptions. The system model determined by LINEAR consists of matrices for both the state and observation equations. The program has been designed to allow easy selection and definition of the state, control, and observation variables to be used in a particular model.

Antoniewicz, Robert F.; Duke, Eugene L.; Patterson, Brian P.

1988-01-01

289

Crossint - an interactive tool for the analysis of normal fault slip rates, using cross sectional data derived from terrestrial laser scan datasets  

NASA Astrophysics Data System (ADS)

We have developed Crossint as an interactive tool for the analysis of normal fault slip rates, using terrestrial laser scan datasets. The long-term slip rate of active normal faults is a key parameter in hazard mapping and planning, as earthquake recurrence intervals decrease (the risk increases) as slip rates increase. Normal fault slip rates measured over geological time-scales are conventionally defined from surface offset surveys of a limited number of sites along a fault, using survey methods such as total station and differential GPS. We present an alternative method of slip rate analysis using a high resolution terrestrial laser scan (TLS) dataset from the Campo Felice fault in the Apennines, central Italy. Individually selected TLS derived cross sections for numerous sites along the length of the fault were interpreted using Crossint to produce a reliable assessment of surface offset and slip rate. Geomorphic features such as gullies, alluvial fans and rotational land slips can alter the perceived surface offset and slip rate along the fault, as such these sites should be avoided. The TLS dataset was filtered using the GEON points2grid utility, allowing us to identify and avoid geomorphic features using robust workflows which generated a hillshade raster, contour and surface dip maps. The result is a revised bulk slip rate for the Campo Felice fault, including the uncertainty and variability inherent to the method and the result. Such confidence parameters are vital in order to properly weight the slip rate within regional hazard models.

Wilkinson, M.; McCaffrey, K. J.; Roberts, G.; Cowie, P. A.

2011-12-01

290

Scattering parameters for cold Li-Rb and Na-Rb collisions derived from variable phase theory  

SciTech Connect

We show how the scattering phase shift, the s-wave scattering length, and the p-wave scattering volume can be obtained from Riccati equations derived in variable phase theory. We find general expressions that provide upper and lower bounds for the scattering length and the scattering volume. We show how, in the framework of the variable phase method, Levinson's theorem yields the number of bound states supported by a potential. We report results from a study of the heteronuclear alkali-metal dimers NaRb and LiRb. We consider ab initio molecular potentials for the X {sup 1}{sigma}{sup +} and a {sup 3}{sigma}{sup +} states of both dimers and compare and discuss results obtained from experimentally based X {sup 1}{sigma}{sup +} and a {sup 3}{sigma}{sup +} potentials of NaRb. We explore the mass dependence of the scattering data by considering all isotopomers and we calculate the numbers of bound states supported by the molecular potentials for each isotopomer.

Ouerdane, H.; Jamieson, M.J. [Department of Computing Science, University of Glasgow, 17 Lilybank Gardens, Glasgow G12 8QQ (United Kingdom)

2004-08-01

291

The 27-28 October 1986 FIRE IFO cirrus case study: Cirrus parameter relationships derived from satellite and lidar data  

NASA Technical Reports Server (NTRS)

Cirrus cloud radiative and physical characteristics are determined using a combination of ground-based, aircraft, and satellite measurements taken as part of the First ISCCP Regional Experiment (FIRE) Cirrus Intensive Field Observations (IFO) during October and November 1986. Lidar backscatter data are used to define cloud base, center, and top heights and the corresponding temperatures. Coincident GOES 4 km visible (0.65 microns) and 8 km infrared window (11.5 microns) radiances are analyzed to determine cloud emittances and reflectances. Infrared optical depth is computed from the emittance results. Visible optical depth is derived from reflectance using a theoretical ice crystal scattering model and an empirical bidirectional reflectance mode. No clouds with visible optical depths greater than 5 or infrared optical depths less than 0.1 were used in the analysis. Average cloud thickness ranged from 0.5 km to 8 km for the 71 scenes. An average visible scattering efficiency of 2.1 was found for this data set. The results reveal a significant dependence of scattering efficiency on cloud temperature.

Minnis, Patrick; Young, David F.; Sassen, Kenneth; Alvarez, Joseph M.; Grund, Christian J.

1989-01-01

292

Optical properties and the dispersion parameters of new zinc Phthalocyanine benzofuran derivative prepared by non-vacuum spin coating technique  

NASA Astrophysics Data System (ADS)

The optical properties of 2(3),9(10),16(17),23(24)-tetrakis-{6-(-benzofuran-2-carboxylate)-hexylthio} phthalocyaninatozinc(II) {Zn[Pc(b-S(CH2)6OCOBz-furan)4], (ZnPcBzF) thin film prepared by spin coating method were investigated. The optical constants of the prepared film were determined using spectrophotometric measurements of the transmittance and reflectance at normal incidence in the spectral range 200-800 nm. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region revealed two direct allowed optical band gap of 2.58 and 3.87 eV. The dispersion of the refractive index was discussed in terms of the single oscillator using Sellmeier dispersion formula. The high frequency dielectric constant (??) and the lattice dielectric constant (?L) were estimated. From the optical constants analysis, the optical conductivity was also considered. Discussion of the obtained results and their comparison with the previous published data were also given. The obtained results of this new zinc phthalocyanine benzofuran derivative (ZnPcBzF) support the desirable feature for the microelectronic and optoelectronic devices.

Farag, A. A. M.; Yahia, I. S.; Yakuphanoglu, F.; Kandaz, M.; Farooq, W. A.

2012-06-01

293

Towards successful user interaction with systems: focusing on user-derived gestures for smart home systems.  

PubMed

Various studies that derived gesture commands from users have used the frequency ratio to select popular gestures among the users. However, the users select only one gesture from a limited number of gestures that they could imagine during an experiment, and thus, the selected gesture may not always be the best gesture. Therefore, two experiments including the same participants were conducted to identify whether the participants maintain their own gestures after observing other gestures. As a result, 66% of the top gestures were different between the two experiments. Thus, to verify the changed gestures between the two experiments, a third experiment including another set of participants was conducted, which showed that the selected gestures were similar to those from the second experiment. This finding implies that the method of using the frequency in the first step does not necessarily guarantee the popularity of the gestures. PMID:24685287

Choi, Eunjung; Kwon, Sunghyuk; Lee, Donghun; Lee, Hogin; Chung, Min K

2014-07-01

294

Hedgehog-mediated paracrine interaction between hepatic stellate cells and marrow-derived mesenchymal stem cells  

SciTech Connect

During liver injury, bone marrow-derived mesenchymal stem cells (MSCs) can migrate and differentiate into hepatocytes. Hepatic stellate cell (SC) activation is a pivotal event in the development of liver fibrosis. Therefore, we hypothesized that SCs may play an important role in regulating MSC proliferation and differentiation through the paracrine signaling pathway. We demonstrate that MSCs and SCs both express hedgehog (Hh) pathway components, including its ligands, receptors, and target genes. Transwell co-cultures of SCs and MSCs showed that the SCs produced sonic hedgehog (Shh), which enhanced the proliferation and differentiation of MSCs. These findings demonstrate that SCs indirectly modulate the activity of MSCs in vitro via the Hh pathway, and provide a plausible explanation for the mechanisms of transplanted MSCs in the treatment of liver fibrosis.

Lin Nan [Division of Hepatology, Third Hospital of Sun Yat-Sen University, Tianhe Road 600, Guangzhou City 510630, Guangdong Province (China)], E-mail: linnancn@gmail.com; Tang Zhaofeng; Deng Meihai; Zhong Yuesi; Lin Jizong [Division of Hepatology, Third Hospital of Sun Yat-Sen University, Tianhe Road 600, Guangzhou City 510630, Guangdong Province (China); Yang Xuhui; Xiang Peng [Center for Stem Cell Biology and Tissue Engineering, Sun Yat-Sen University, Guangzhou City, Guangdong Province (China); Xu Ruiyun [Division of Hepatology, Third Hospital of Sun Yat-Sen University, Tianhe Road 600, Guangzhou City 510630, Guangdong Province (China)

2008-07-18

295

Study on the interaction of amino phosphine ester derivatives with DNA by spectroscopy, modeling and calorimetry  

NASA Astrophysics Data System (ADS)

The binding properties of amino phosphate ester derivatives, compound 1 and 2 with calf thymus DNA (CT-DNA) were investigated by UV spectra, fluorescence spectra, molecular modeling and isothermal titration calorimetry (ITC). The intrinsic binding constants Kb of compound 1 and 2 with CT-DNA were determined by fluorescence spectroscopy and ITC, respectively. The results indicated that the two compounds bind to CT-DNA with different binding affinity, which is in the order of compound 1 > compound 2. At the same time, fluorescence spectra suggested that the mechanism of the binding of the two compounds to CT-DNA is a static enhancing type. According to the ethidium bromide displacement experiments, UV spectra, molecular modeling and ITC studies, it can be concluded that compound 1 and 2 are intercalators that can slide into the G-C rich region of CT-DNA. Furthermore, ITC data showed that compound/DNA binding is enthalpy controlled.

Lu, Yan; Wang, Gongke; Tang, Wen; Hao, Xiaoxiao; Xu, Meihua; Li, Xiang

2011-11-01

296

Enhanced Detection of Open-angle Glaucoma with an Anatomically Accurate Optical Coherence Tomography-Derived Neuroretinal Rim Parameter  

PubMed Central

Objective Neuroretinal rim assessment based on the clinical optic disc margin (DM) lacks a sound anatomic basis for 2 reasons: (1) The DM is not reliable as the outer border of rim tissue because of clinically and photographically invisible extensions of Bruch’s membrane (BM) inside the DM and (2) nonaccountability of rim tissue orientation in the optic nerve head (ONH). The BM opening-minimum rim width (BMO-MRW) is a parameter that quantifies the rim from its true anatomic outer border, BMO, and accounts for its variable orientation. We report the diagnostic capability of BMO-MRW. Design Case control. Participants Patients with open-angle glaucoma (n = 107) and healthy controls (n = 48). Methods Spectral-domain optical coherence tomography (SD-OCT) with 24 radial and 1 circumpapillary B-scans, centered on the ONH, and confocal scanning laser tomography (CSLT) were performed. The internal limiting membrane (ILM) and BMO were manually segmented in each radial B-scan. Three SD-OCT parameters were computed globally and sectorally: (1) circumpapillary retinal nerve fiber layer thickness (RNFLT); (2) BMO-horizontal rim width (BMO-HRW), the distance between BMO and ILM in the BMO reference plane; and (3) BMO-MRW, the minimum distance between BMO and ILM. Moorfields Regression Analysis (MRA) with CLST was performed globally and sectorally to yield MRA1 and MRA2, where “borderline” was classified as normal and abnormal, respectively. Main Outcome Measures Sensitivity, specificity, and likelihood ratios (LRs) for positive and negative test results (LR+/LR?). Results The median (interquartile range) age and mean deviation of patients and controls were 69.9 (64.3–76.9) and 65.0 (58.1–74.3) years and ?3.92 (?7.87 to ?1.62) and 0.33 (?0.32 to 0.98) dB, respectively. Globally, BMO-MRW yielded better diagnostic performance than the other parameters. At 95% specificity, the sensitivity of RNFLT, BMO-HRW, and BMO-MRW was 70%, 51%, and 81%, respectively. The corresponding LR+/LR? was 14.0/0.3, 10.2/0.5, and 16.2/0.2. Sectorally, at 95% specificity, the sensitivity of RNFLT ranged from 31% to 59%, of BMO-HRW ranged from 35% to 64%, and of BMO-MRW ranged from 54% to 79%. Globally and in all sectors, BMO-MRW performed better than MRA1 or MRA2. Conclusions The higher sensitivity at 95% specificity in early glaucoma of BMO-MRW compared with current BMO methods is significant, indicating a new structural marker for the detection and risk profiling of glaucoma. PMID:23265804

Chauhan, Balwantray C.; O'Leary, Neil; AlMobarak, Faisal A.; Reis, Alexandre S. C.; Yang, Hongli; Sharpe, Glen P.; Hutchison, Donna M.; Nicolela, Marcelo T.; Burgoyne, Claude F.

2013-01-01

297

Synergy between optical and microwave remote sensing to derive soil and vegetation parameters from MAC Europe 1991 Experiment  

NASA Technical Reports Server (NTRS)

The ability of remote sensing for monitoring vegetation density and soil moisture for agricultural applications is extensively studied. In optical bands, vegetation indices (NDVI, WDVI) in visible and near infrared reflectances are related to biophysical quantities as the leaf area index, the biomass. In active microwave bands, the quantitative assessment of crop parameters and soil moisture over agricultural areas by radar multiconfiguration algorithms remains prospective. Furthermore the main results are mostly validated on small test sites, but have still to be demonstrated in an operational way at a regional scale. In this study, a large data set of radar backscattering has been achieved at a regional scale on a French pilot watershed, the Orgeval, along two growing seasons in 1988 and 1989 (mainly wheat and corn). The radar backscattering was provided by the airborne scatterometer ERASME, designed at CRPE, (C and X bands and HH and VV polarizations). Empirical relationships to estimate water crop and soil moisture over wheat in CHH band under actual field conditions and at a watershed scale are investigated. Therefore, the algorithms developed in CHH band are applied for mapping the surface conditions over wheat fields using the AIRSAR and TMS images collected during the MAC EUROPE 1991 experiment. The synergy between optical and microwave bands is analyzed.

Taconet, O.; Benallegue, M.; Vidal, A.; Vidal-Madjar, D.; Prevot, L.; Normand, M.

1993-01-01

298

Application of imaging-derived parameters to dosimetry of intravascular brachytherapy sources: perturbation effects of residual plaque burden.  

PubMed

The dosimetric effect of geometric and material heterogeneities on intravascular brachytherapy dose delivery has been studied recently. Residual plaque within the coronary vessel appears to have an impact on the uniform delivery of radiation dose to the arterial tissue. In this study, we have examined the effect of residual plaque burden and post-PCI (percutaneous coronary intervention) plaque configuration on the dose to the arterial wall from clinical intravascular brachytherapy beta-emitting sources containing 32P and 90Sr/90Y. Monte Carlo simulations using the MCNP4B code were performed for these catheter-based sources with residual plaque burden ranging between 25% and 50%. The residual plaque burden values were derived from post-PCI data provided in several recent clinical studies. Dose calculations were performed for three different values of plaque density (1.45 g cm(-3), 2.20 g cm(-3), and 3.1 g cm(-3)) and three different plaque morphologies for the same residual plaque burden. The dose perturbation factor (DPF), defined as the ratio of dose at 2 mm radial distance for a given case to the dose at the same radial distance in homogeneous water medium, was determined for each of the three different plaque densities. The range of DPF values was 0.81-1.01, 0.62-0.99, and 0.41-0.97 for different plaque densities for the 32P source. Corresponding DPF values for the 90Sr/90Y source were 0.90-1.01, 0.84-1.01, and 0.62-1.01. The results indicate the need for accurate assessment of post-PCI clinical measurements such as minimal lumen diameter and residual plaque burden and incorporation of these values into dose calculations. PMID:12148741

Sehgal, Varun; Li, Zuofeng; Palta, Jatinder R; Smith, Karen M; Bolch, W E

2002-07-01

299

Tensor Interaction Limit Derived From the ?-?-?¯ Correlation in Trapped Li8 Ions  

NASA Astrophysics Data System (ADS)

A measurement of the ?-?-?¯ angular correlation in the Gamow-Teller decay Li8?Be*8+?¯+?, Be*8??+? has been performed using ions confined in a linear Paul trap surrounded by silicon detectors. The energy difference spectrum of the ? particles emitted along and opposite the direction of the ? particle is consistent with the standard model prediction and places a limit of 3.1% (95.5% confidence level) on any tensor contribution to the decay. From this result, the amplitude of any tensor component CT relative to that of the dominant axial-vector component CA of the electroweak interaction is limited to |CT/CA|<0.18 (95.5% confidence level). This experimental approach is facilitated by several favorable features of the Li8 ? decay and has different systematic effects than the previous ?-?¯ correlation results for a pure Gamow-Teller transition obtained from studying He6 ? decay.

Li, G.; Segel, R.; Scielzo, N. D.; Bertone, P. F.; Buchinger, F.; Caldwell, S.; Chaudhuri, A.; Clark, J. A.; Crawford, J. E.; Deibel, C. M.; Fallis, J.; Gulick, S.; Gwinner, G.; Lascar, D.; Levand, A. F.; Pedretti, M.; Savard, G.; Sharma, K. S.; Sternberg, M. G.; Sun, T.; Van Schelt, J.; Yee, R. M.; Zabransky, B. J.

2013-03-01

300

Target dependence of clan model parameter in 84 Kr 36 - Emulsion interactions at 1 GeV per nucleon  

NASA Astrophysics Data System (ADS)

The article focuses on study of clan model parameters and their target dependence in light of void probability scaling for heavy (Ag and Br) and light (C, N and O) groups of targets present in nuclear emulsion detector using 84 Kr 36 at around 1 A GeV. The variation of scaled rapidity gap (rap gap) probability with single moment combination has been studied. We found that experimental points are lying approximately on the negative binomial distribution (NBD) curve, indicating a scaling behavior. The average clan multiplicities for interactions, increases with the pseudo-rapidity interval was also observed. The values of average multiplicity for AgBr targets are larger than those for CNO target and also average number of particles per clan increases with increase in pseudo-rapidity interval. We further observed that for a particular target, average number of particles per clan increases with an increase in the size of projectile nucleus.

Singh, M. K.; Soma, A. K.; Singh, V.; Pathak, R.

2014-09-01

301

Interaction of nickel-based SOFC anodes with trace contaminants from coal-derived synthesis gas  

NASA Astrophysics Data System (ADS)

New and efficient methods of producing electrical energy from natural resources have become an important topic for researchers. Integrated gasification and fuel cell (IGFC) systems offer a fuel-flexible, high-efficiency method of energy generation. Specifically, in coal gasification processes, coal can be changed into a high-quality gaseous fuel suitable for feeding solid oxide fuel cells (SOFCs). However, trace species found in coal synthesis gas (syngas) may have a deleterious effect on the performance of nickel-based SOFC anodes. Generally, the cost of removing these species down to parts per million (ppm) levels is high. The purpose of this research is to determine the highest amount of contaminant that results in a low rate (˜1% per 1000 h) of cell performance degradation, allowing the SOFC to produce usable power for 40,000 hours. The cell performance degradation rate was determined for benzene, naphthalene, and mercury-doped syngas based on species concentration. Experimental data are fitted with degradation models to predict cell lifetime behavior. From these results, the minimum coal syngas cleanup required for these trace materials is determined. It is found that for a final cell voltage of 0.6 V, naphthalene and benzene must be cleaned to 360 ppm and less than 150 ppm, respectively. No additional cleaning is required for mercury beyond established environmental standards. Additionally, a detailed attack and recovery mechanism is proposed for the hydrocarbon species and their interaction with the fuel cell. This mechanism is proposed by considering the type of degradation models predicted and how carbon would interact with the Ni-YSZ anode to justify those models. The mechanism postulates that carbon is diffusing into the nickel structure, creating a metal solution. Once the nickel is saturated, the carbon begins to deposit on the nickel surface, reducing the electrode active area. The formation of metal solutions and the deposition of carbon results in reduced cell productivity.

Hackett, Gregory Allen

302

How Short Is Too Short for the Interactions of a Water Potential? Exploring the Parameter Space of a Coarse-Grained Water Model  

E-print Network

How Short Is Too Short for the Interactions of a Water Potential? Exploring the Parameter Space of a Coarse-Grained Water Model Using Uncertainty Quantification Liam C. Jacobson, Robert M. Kirby sample the five-dimensional parameter space of the coarse-grained monatomic water (mW) model to determine

Kirby, Mike

303

Quantifying parameter sensitivity, interaction, and transferability in hydrologically enhanced versions of the Noah land surface model over transition zones during the warm season  

Microsoft Academic Search

We use sensitivity analysis to identify the parameters that are most responsible for controlling land surface model (LSM) simulations and to understand complex parameter interactions in three versions of the Noah LSM: the standard version (STD), a version enhanced with a simple groundwater module (GW), and version augmented by a dynamic phenology module (DV). We use warm season, high-frequency, near-surface

Enrique Rosero; Zong-Liang Yang; Thorsten Wagener; Lindsey E. Gulden; Soni Yatheendradas; Guo-Yue Niu

2010-01-01

304

Quantifying the uncertainty of Landsat tm derived energy balance parameters in the discontinuous permafrost zone: A Monte Carlo approach  

NASA Astrophysics Data System (ADS)

High latitude regions are proving to be highly sensitive to climatic change as indicated by shifts in plant communities and other surface properties. Such transitions in the vegetated surface result in differences in the absorption and partitioning of incident solar radiation with uncertain consequences for regional climate. Simple descriptions of surface and subsurface changes over time in the discontinuous permafrost zone often remain elusive because of the complex spatial patterning of vegetated surface. The analysis of remote sensing data to determine the spatial extent and location of different surface features, and their changes, provides a means to track the temporal changes that have occurred since the dawn of of the remote sensing data record. Here, we evaluate the uncertainties associated with generating albedo from Landsat tm. There are two primary sources of uncertainty in the albedo product generated from Landsat; uncertainty associated with coefficients assigned to Landsat bands for generating albedo, and uncertainty in the raw digital remote sensing values. We employed a Monte Carlo method of random parameter generation and implementation of these coefficients to characterize changes to and uncertainty in Landsat albedo in an area of pronounced thaw in the discontinuous permafrost zone in west-central Alaska. The motivation for the uncertainty analysis is to quantify significant changes to land surface properties over time. Results indicate that the overall variability in the albedo layer is not strongly impacted by the coefficients applied to the Landsat data bands, and more affected by the variance within the Landsat data (Figure 1). Changes in albedo over the past 40 years tend to be concentrated along the edges of existing features, especially lakes.

Johnson, A.; Stoy, P.; Ewing, S. A.

2013-12-01

305

Derivation of physiological inhalation rates in children, adults, and elderly based on nighttime and daytime respiratory parameters.  

PubMed

The methodology developed in our previous studies ( Brochu et al. 2006a-c ) for the determination of physiological daily inhalation rates was improved by integrating into the calculation process, both nighttime and daytime respiratory parameters, namely oxygen uptake factors (H) and ventilatory equivalents (VQ). H values during fasting (0.2057±0.0018 L of O2/kcal; mean±SD) and postprandial phases (0.2059±0.0019 L of O2/kcal) as well as VQ values for subjects at rest (27.4±4.8 to 32.2±3.1, unitless) and during the aggregate daytime activities (29.9±4.2 to 33.7±7.2) were determined and combined with published doubly labeled water measurements for the calculation of daily inhalation rates in normal-weight males and females aged 0.22-96 years (n=1235). Depending upon the unit value chosen, the highest 99th percentiles for inhalation data were found in males aged 35 to <45 years (35.40 m3/day), 2.6 to <6 months (1.138 m3/kg-day), and 10 to <16.5 years (22.29 m3/m2-day). Means and percentiles expressed in m3/kg-day as well as in m3/m2-day suggest generally higher intakes of air pollutants in children than in adults and in males than in females (in g/kg-day or g/m2-day) for identical exposure concentrations and conditions. For instance, means in boys aged 2.6 to <6 months of 10.99±3.50 m3/m2-day and 0.572±0.191 m3/kg-day are 1.3- and 2.5-folds higher, respectively, than those in adult males 65?96 years old (8.42±2.13 m3/m2-day, 0.225±0.059 m3/kg-day). PMID:21299435

Brochu, Pierre; Brodeur, Jules; Krishnan, Kannan

2011-02-01

306

Identification of novel GAPDH-derived antimicrobial peptides secreted by Saccharomyces cerevisiae and involved in wine microbial interactions.  

PubMed

Saccharomyces cerevisiae plays a primordial role in alcoholic fermentation and has a vast worldwide application in the production of fuel-ethanol, food and beverages. The dominance of S. cerevisiae over other microbial species during alcoholic fermentations has been traditionally ascribed to its higher ethanol tolerance. However, recent studies suggested that other phenomena, such as microbial interactions mediated by killer-like toxins, might play an important role. Here we show that S. cerevisiae secretes antimicrobial peptides (AMPs) during alcoholic fermentation that are active against a wide variety of wine-related yeasts (e.g. Dekkera bruxellensis) and bacteria (e.g. Oenococcus oeni). Mass spectrometry analyses revealed that these AMPs correspond to fragments of the S. cerevisiae glyceraldehyde 3-phosphate dehydrogenase (GAPDH) protein. The involvement of GAPDH-derived peptides in wine microbial interactions was further sustained by results obtained in mixed cultures performed with S. cerevisiae single mutants deleted in each of the GAPDH codifying genes (TDH1-3) and also with a S. cerevisiae mutant deleted in the YCA1 gene, which codifies the apoptosis-involved enzyme metacaspase. These findings are discussed in the context of wine microbial interactions, biopreservation potential and the role of GAPDH in the defence system of S. cerevisiae. PMID:24292082

Branco, Patrícia; Francisco, Diana; Chambon, Christophe; Hébraud, Michel; Arneborg, Nils; Almeida, Maria Gabriela; Caldeira, Jorge; Albergaria, Helena

2014-01-01

307

Biospecific interactions of Vitamin K-dependent factors with phospholipid-like polystyrene derivatives. Part I: Factor II.  

PubMed

Phosphorylated polystyrene derivatives with different compositions in phosphate groups were shown to be either recognized as phospholipidic or as DNA-like surfaces by antibodies from Systemic Lupus Erythematosus patients. In order to check whether these polymers were able to interact with Vitamin K-dependent coagulation factors, phosphorylated resins of various compositions in phosphate groups were assessed with regard to their interactions with Factor II, one of the Vitamin K-dependent factors. These studies were performed either in the presence or the absence of calcium ions, and with or without albumin precoating of the polymers. The results show that the affinity of the protein for the polymer is increased in the presence of calcium ions and depends on the composition of the polymer. The protein-polymer interactions involve the formation of binary or ternary complexes and the domains of predominance of these complexes were determined as a function of the calcium ion concentration in the assay. This allowed us to propose optimal conditions for Factor II purification by highly specific liquid chromatography using phosphorylated polystyrene resins of given compositions as stationary phases. PMID:8730967

Migonney, V; Ménard, V; Jozéfowicz, M

1996-04-01

308

Epigenetic and epistatic interactions between serotonin transporter and brain-derived neurotrophic factor genetic polymorphism: insights in depression.  

PubMed

Epidemiological studies have shown significant results in the interaction between the functions of brain-derived neurotrophic factor (BDNF) and 5-HT in mood disorders, such as major depressive disorder (MDD). The latest research has provided convincing evidence that gene transcription of these molecules is a target for epigenetic changes, triggered by stressful stimuli that starts in early childhood and continues throughout life, which are subsequently translated into structural and functional phenotypes culminating in depressive disorders. The short variants of 5-HTTLPR and BDNF-Met are seen as forms which are predisposed to epigenetic aberrations, which leads individuals to a susceptibility to environmental adversities, especially when subjected to stress in early life. Moreover, the polymorphic variants also feature epistatic interactions in directing the functional mechanisms elicited by stress and underlying the onset of depressive disorders. Also emphasized are works which show some mediators between stress and epigenetic changes of the 5-HTT and BDNF genes, such as the hypothalamic-pituitary-adrenal (HPA) axis and the cAMP response element-binding protein (CREB), which is a cellular transcription factor. Both the HPA axis and CREB are also involved in epistatic interactions between polymorphic variants of 5-HTTLPR and Val66Met. This review highlights some research studying changes in the epigenetic patterns intrinsic to genes of 5-HTT and BDNF, which are related to lifelong environmental adversities, which in turn increases the risks of developing MDD. PMID:24972302

Ignácio, Z M; Réus, G Z; Abelaira, H M; Quevedo, J

2014-09-01

309

HIV-1 Interacts with Human Endogenous Retrovirus K (HML-2) Envelopes Derived from Human Primary Lymphocytes  

PubMed Central

ABSTRACT Human endogenous retroviruses (HERVs) are viruses that have colonized the germ line and spread through vertical passage. Only the more recently acquired HERVs, such as the HERV-K (HML-2) group, maintain coding open reading frames. Expression of HERV-Ks has been linked to different pathological conditions, including HIV infection, but our knowledge on which specific HERV-Ks are expressed in primary lymphocytes currently is very limited. To identify the most expressed HERV-Ks in an unbiased manner, we analyzed their expression patterns in peripheral blood lymphocytes using Pacific Biosciences (PacBio) single-molecule real-time (SMRT) sequencing. We observe that three HERV-Ks (KII, K102, and K18) constitute over 90% of the total HERV-K expression in primary human lymphocytes of five different donors. We also show experimentally that two of these HERV-K env sequences (K18 and K102) retain their ability to produce full-length and posttranslationally processed envelope proteins in cell culture. We show that HERV-K18 Env can be incorporated into HIV-1 but not simian immunodeficiency virus (SIV) particles. Moreover, HERV-K18 Env incorporation into HIV-1 virions is dependent on HIV-1 matrix. Taken together, we generated high-resolution HERV-K expression profiles specific for activated human lymphocytes. We found that one of the most abundantly expressed HERV-K envelopes not only makes a full-length protein but also specifically interacts with HIV-1. Our findings raise the possibility that these endogenous retroviral Env proteins could directly influence HIV-1 replication. IMPORTANCE Here, we report the HERV-K expression profile of primary lymphocytes from 5 different healthy donors. We used a novel deep-sequencing technology (PacBio SMRT) that produces the long reads necessary to discriminate the complexity of HERV-K expression. We find that primary lymphocytes express up to 32 different HERV-K envelopes, and that at least two of the most expressed Env proteins retain their ability to make a protein. Importantly, one of them, the envelope glycoprotein of HERV-K18, is incorporated into HIV-1 in an HIV matrix-specific fashion. The ramifications of such interactions are discussed, as the possibility of HIV-1 target tissue broadening and immune evasion are considered. PMID:24648457

Brinzevich, Daria; Young, George R.; Sebra, Robert; Ayllon, Juan; Maio, Susan M.; Deikus, Gintaras; Chen, Benjamin K.; Fernandez-Sesma, Ana; Simon, Viviana

2014-01-01

310

TRADES: A new software to derive orbital parameters from observed transit times and radial velocities. Revisiting Kepler-11 and Kepler-9  

NASA Astrophysics Data System (ADS)

Aims: With the purpose of determining the orbital parameters of exoplanetary systems from observational data, we have developed a software, named TRADES (TRAnsits and Dynamics of Exoplanetary Systems), to simultaneously fit observed radial velocities and transit times data. Methods: We implemented a dynamical simulator for N-body systems, which also fits the available data during the orbital integration and determines the best combination of the orbital parameters using grid search, ?2 minimization, genetic algorithms, particle swarm optimization, and bootstrap analysis. Results: To validate TRADES, we tested the code on a synthetic three-body system and on two real systems discovered by the Kepler mission: Kepler-9 and Kepler-11. These systems are good benchmarks to test multiple exoplanet systems showing transit time variations (TTVs) due to the gravitational interaction among planets. We have found that orbital parameters of Kepler-11 planets agree well with the values proposed in the discovery paper and with a a recent work from the same authors. We analyzed the first three quarters of Kepler-9 system and found parameters in partial agreement with discovery paper. Analyzing transit times (T0s), covering 12 quarters of Kepler data, that we have found a new best-fit solution. This solution outputs masses that are about 55% of the values proposed in the discovery paper; this leads to a reduced semi-amplitude of the radial velocities of about 12.80 ms-1.

Borsato, L.; Marzari, F.; Nascimbeni, V.; Piotto, G.; Granata, V.; Bedin, L. R.; Malavolta, L.

2014-11-01

311

Temperature dependence of interactions between stable piperidine-1-yloxyl derivatives and a semicrystalline ionic liquid.  

PubMed

The stable 2,2,6,6-tetramethylpiperidine-1-yloxyl and its derivatives with hydrogen-bond-forming (-OH, -OSO(3)H), anionic (-OSO(3) (-) bearing K(+) or [K(18-crown-6)](+) as counter ion), or cationic (-N(+)(CH(3))(3) bearing I(-), BF(4) (-), PF(6) (-) or N(-)(SO(2)CF(3))(2) as counter ion) substituents are investigated in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide over a wide temperature range. The temperature dependence of the viscosity of the ionic liquid is well described by the Vogel-Fulcher-Tammann equation. Interestingly, the temperature dependence of the rotational correlation time of the spin probes substituted with either a hydrogen-bond-forming group or an ionic substituent can be described using the Stokes-Einstein equation. In contrast, the temperature dependence of the rotational correlation time of the spin probe without an additional substituent at the 4-position to the nitroxyl group does not follow this trend. The activation energy for the mobility of the unsubstituted spin probe, determined from an Arrhenius plot of the spin-probe mobility in the ionic liquid above the melting temperature, is comparable with the activation energy for the viscous flow of the ionic liquid, but is higher for spin probes bearing an additional substituent at the 4-position. Quantum chemical calculations of the spin probes using the 6-31G+d method give information about the rotational volume of the spin probes and the spin density at the nitrogen atom of the radical structure as a function of the substituent at the spin probes in the presence and absence of a counter ion. The results of these calculations help in understanding the effect of the additional substituent on the experimentally determined isotropic hyperfine coupling constant. PMID:20486149

Strehmel, Veronika; Rexhausen, Hans; Strauch, Peter; Strehmel, Bernd

2010-07-12

312

Image-Based Quantification of Benzoporphyrin Derivative Uptake, Localization, and Photobleaching in 3D Tumor Models, for Optimization of PDT Parameters  

PubMed Central

Photodynamic therapy (PDT) is a light-based treatment modality in which wavelength specific activation of a photosensitizer (PS) generates cytotoxic response in the irradiated region. PDT response is critically dependent on several parameters including light dose, PS dose, uptake time, fluence rate, and the mode of light delivery. While the systematic optimization of these treatment parameters can be complex, it also provides multiple avenues for enhancement of PDT efficacy under diverse treatment conditions, provided that a rational framework is established to quantify the impact of parameter selection upon treatment response. Here we present a theranostic technique, combining the inherent ability of the PS to serve simultaneously as a therapeutic and imaging agent, with the use of image-based treatment assessment in three dimensional (3D) in vitro tumor models, to comprise a platform to evaluate the impact of PDT parameters on treatment outcomes. We use this approach to visualize and quantify the uptake, localization, and photobleaching of the PS benzoporphyrin derivative monoacid ring-A (BPD) in a range of treatment conditions with varying uptake times as well as continuous and fractionated light delivery regimens in 3D cultures of AsPC-1 and PANC-1 cells. Informed by photobleaching patterns and correlation with cytotoxic response, asymmetric fractionated light delivery at 4 hours BPD uptake was found to be the most effective regimen assessed. Quantification of the spatial profile of cell killing within multicellular nodules revealed that these conditions also achieve the highest depth of cytotoxicity along the radial axis of 3D nodules. The framework introduced here provides a means for systematic assessment of PDT treatment parameters in biologically relevant 3D tumor models with potential for broader application to other systems. PMID:23082096

Glidden, Michael D.; Celli, Jonathan P.; Massodi, Iqbal; Rizvi, Imran; Pogue, Brian W.; Hasan, Tayyaba

2012-01-01

313

Interface contributions to the spin-orbit interaction parameters of electrons at the (001) GaAs/AlGaAs interface  

NASA Astrophysics Data System (ADS)

One-body mechanisms of spin splitting of the energy spectrum of 2D electrons in a one-side doped (001) GaAs/Al x Ga1 - x As quantum well have been studied theoretically and experimentally. The interfacial spin splitting has been shown to compensate (enhance) considerably the contribution of the bulk Dresselhaus (Bychkov-Rashba) mechanism. The theoretical approach is based on the solution of the effective mass equation in a quasi-triangular well supplemented by a new boundary condition at a high and atomically sharp hetero-barrier. The model takes into account the spin-orbit interaction of electrons with both bulk and interfacial crystal potential having C 2 v symmetry, as well as the lack of inversion symmetry and nonparabolicity of the conduction band in GaAs. The effective 2D spin Hamiltonian including both bulk and interface contributions to the Dresselhaus (?BIA) and Rashba (?SIA) constants has been derived. The analytical relation between these constants and the components of the anisotropic nonlinear g-factor tensor in an oblique quantizing magnetic field has been found. The experimental approach is based, on one hand, on the detection of electron spin resonance in the microwave range and, on the other hand, on photoluminescence measurements of the nonparabolicity parameter. The interface contributions to ?BIA and ?SIA have been found from comparison with the theory.

Devizorova, Zh. A.; Shchepetilnikov, A. V.; Nefyodov, Yu. A.; Volkov, V. A.; Kukushkin, I. V.

2014-09-01

314

Effects and Interactions of Medium Components on Laccase from a Marine-Derived Fungus Using Response Surface Methodology  

PubMed Central

The effects of various synthetic medium components and their interactions with each other ultimately impact laccase production in fungi. This was studied using a laccase-hyper-producing marine-derived basidiomycete, Cerrena unicolor MTCC 5159. Inducible laccases were produced in the idiophase only after addition of an inducer such as CuSO4. Concentration of carbon and nitrogen acted antagonistically with respect to laccase production. A combination of low nitrogen and high carbon concentration favored both biomass and laccase production. The most favorable combination resulted in 917 U L?1 of laccase. After sufficient growth had occurred, addition of a surfactant such as Tween 80 positively impacted biomass and increased the laccase activity to around 1,300 U L?1. Increasing the surface to volume ratio of the culture vessel further increased its activity to almost 2,000 U L?1. PMID:20098606

D’Souza-Ticlo, Donna; Garg, Sandeep; Raghukumar, Chandralata

2009-01-01

315

Interactions of Fullerene (C60) and its Hydroxyl Derivatives with Lipid Bilayer: A Coarse-Grained Molecular Dynamics Simulation  

NASA Astrophysics Data System (ADS)

Coarse-grained molecular dynamic simulations were employed to study the interactions of fullerene (C60) and its hydroxyl derivatives (C60(OH)n, n = 4, 5, 6, 8, 12, and 16) with a lipid bilayer composed of dipalmitoylphosphatidylcholine molecules. It was found that the C60 moves towards the center of the bilayer and laid between central and peripheral regions of the bilayer. The potential mean force was calculated to estimate free energy profile when pulling the fullerene from its initial position to the center of the bilayer using an umbrella sampling method. Results showed that the hydrophobic region of the membrane acts as a barrier to transport a nonpolar C60 molecule through the bilayer. This makes a deep minimum in the free energy profile between the center and head regions of membrane. Various numbers of polar functional groups (-OH) were then used to make derivatives of fullerene and change the hydrophilic of the molecule. It was found that optimal number of hydroxyl groups to facilitate the transportation of C60(OH)n through the bilayer is 4.

Mohammadyani, Dariush; Modarress, Hamid; To, Alber C.; Amani, Amir

2013-12-01

316

Specific Interaction between Mycobacterium tuberculosis Lipoprotein-derived Peptides and Target Cells Inhibits Mycobacterial Entry In Vitro.  

PubMed

Tuberculosis (TB) continues being one of the diseases having the greatest mortality rates around the world, 8.7 million cases having been reported in 2011. An efficient vaccine against TB having a great impact on public health is an urgent need. Usually, selecting antigens for vaccines has been based on proteins having immunogenic properties for patients suffering TB and having had promising results in mice and non-human primates. Our approach has been based on a functional approach involving the pathogen-host interaction in the search for antigens to be included in designing an efficient, minimal, subunit-based anti-TB vaccine. This means that Mycobacterium tuberculosis has mainly been involved in studies and that lipoproteins represent an important kind of protein on the cell envelope which can also contribute towards this pathogen's virulence. This study has assessed the expression of four lipoproteins from M. tuberculosis H37Rv, that is, Rv1411c (LprG), Rv1911c (LppC), Rv2270 (LppN) and Rv3763 (LpqH), and the possible biological activity of peptides derived from these. Five peptides were found for these proteins which had high specific binding to both alveolar A549 epithelial cells and U937 monocyte-derived macrophages which were able to significantly inhibit mycobacterial entry to these cells in vitro. PMID:25041568

Ocampo, Marisol; Curtidor, Hernando; Vanegas, Magnolia; Patarroyo, Manuel A; Patarroyo, Manuel E

2014-12-01

317

A knowledge-based scoring function for protein-RNA interactions derived from a statistical mechanics-based iterative method  

PubMed Central

Protein-RNA interactions play important roles in many biological processes. Given the high cost and technique difficulties in experimental methods, computationally predicting the binding complexes from individual protein and RNA structures is pressingly needed, in which a reliable scoring function is one of the critical components. Here, we have developed a knowledge-based scoring function, referred to as ITScore-PR, for protein-RNA binding mode prediction by using a statistical mechanics-based iterative method. The pairwise distance-dependent atomic interaction potentials of ITScore-PR were derived from experimentally determined protein–RNA complex structures. For validation, we have compared ITScore-PR with 10 other scoring methods on four diverse test sets. For bound docking, ITScore-PR achieved a success rate of up to 86% if the top prediction was considered and up to 94% if the top 10 predictions were considered, respectively. For truly unbound docking, the respective success rates of ITScore-PR were up to 24 and 46%. ITScore-PR can be used stand-alone or easily implemented in other docking programs for protein–RNA recognition. PMID:24476917

Huang, Sheng-You; Zou, Xiaoqin

2014-01-01

318

A knowledge-based scoring function for protein-RNA interactions derived from a statistical mechanics-based iterative method.  

PubMed

Protein-RNA interactions play important roles in many biological processes. Given the high cost and technique difficulties in experimental methods, computationally predicting the binding complexes from individual protein and RNA structures is pressingly needed, in which a reliable scoring function is one of the critical components. Here, we have developed a knowledge-based scoring function, referred to as ITScore-PR, for protein-RNA binding mode prediction by using a statistical mechanics-based iterative method. The pairwise distance-dependent atomic interaction potentials of ITScore-PR were derived from experimentally determined protein-RNA complex structures. For validation, we have compared ITScore-PR with 10 other scoring methods on four diverse test sets. For bound docking, ITScore-PR achieved a success rate of up to 86% if the top prediction was considered and up to 94% if the top 10 predictions were considered, respectively. For truly unbound docking, the respective success rates of ITScore-PR were up to 24 and 46%. ITScore-PR can be used stand-alone or easily implemented in other docking programs for protein-RNA recognition. PMID:24476917

Huang, Sheng-You; Zou, Xiaoqin

2014-04-01

319

Measurement of the $?$-asymmetry parameter of $^{67}$Cu in search for tensor type currents in the weak interaction  

E-print Network

Precision measurements at low energy search for physics beyond the Standard Model in a way complementary to searches for new particles at colliders. In the weak sector the most general $\\beta$ decay Hamiltonian contains, besides vector and axial-vector terms, also scalar, tensor and pseudoscalar terms. Current limits on the scalar and tensor coupling constants from neutron and nuclear $\\beta$ decay are on the level of several percent. The goal of this paper is extracting new information on tensor coupling constants by measuring the $\\beta$-asymmetry parameter in the pure Gamow-Teller decay of $^{67}$Cu, thereby testing the V-A structure of the weak interaction. An iron sample foil into which the radioactive nuclei were implanted was cooled down to milliKelvin temperatures in a $^3$He-$^4$He dilution refrigerator. An external magnetic field of 0.1 T, in combination with the internal hyperfine magnetic field, oriented the nuclei. The anisotropic $\\beta$ radiation was observed with planar high purity germanium detectors operating at a temperature of about 10\\,K. An on-line measurement of the $\\beta$ asymmetry of $^{68}$Cu was performed as well for normalization purposes. Systematic effects were investigated using Geant4 simulations. The experimental value, $\\tilde{A}$ = 0.587(14), is in agreement with the Standard Model value of 0.5991(2) and is interpreted in terms of physics beyond the Standard Model. The limits obtained on possible tensor type charged currents in the weak interaction hamiltonian are -0.045 $< (C_T+C'_T)/C_A <$ 0.159 (90\\% C.L.). The obtained limits are comparable to limits from other correlation measurements in nuclear $\\beta$ decay and contribute to further constraining tensor coupling constants.

G. Soti; F. Wauters; M. Breitenfeldt; P. Finlay; P. Herzog; A. Knecht; U. Köster; I. S. Kraev; T. Porobic; P. N. Prashanth; I. S. Towner; C. Tramm; D. Zákoucký; N. Severijns

2014-09-05

320

Measurement of the ?-asymmetry parameter of Cu67 in search for tensor-type currents in the weak interaction  

NASA Astrophysics Data System (ADS)

Background: Precision measurements at low energy search for physics beyond the standard model in a way complementary to searches for new particles at colliders. In the weak sector the most general ?-decay Hamiltonian contains, besides vector and axial-vector terms, also scalar, tensor, and pseudoscalar terms. Current limits on the scalar and tensor coupling constants from neutron and nuclear ? decay are on the level of several percent. Purpose: Extracting new information on tensor coupling constants by measuring the ?-asymmetry parameter in the pure Gamow-Teller decay of Cu67, thereby testing the V-A structure of the weak interaction. Method: An iron sample foil into which the radioactive nuclei were implanted was cooled down to mK temperatures in a 3He-4He dilution refrigerator. An external magnetic field of 0.1 T, in combination with the internal hyperfine magnetic field, oriented the nuclei. The anisotropic ? radiation was observed with planar high-purity germanium detectors operating at a temperature of about 10 K. An on-line measurement of the ? asymmetry of Cu68 was performed as well for normalization purposes. Systematic effects were investigated using geant4 simulations. Results: The experimental value, Ã=0.587(14), is in agreement with the standard model value of 0.5991(2) and is interpreted in terms of physics beyond the standard model. The limits obtained on possible tensor-type charged currents in the weak interaction Hamiltonian are -0.045<(CT+CT')/CA<0.159 (90% C.L.). Conclusions: The obtained limits are comparable to limits from other correlation measurements in nuclear ? decay and contribute to further constraining tensor coupling constants.

Soti, G.; Wauters, F.; Breitenfeldt, M.; Finlay, P.; Herzog, P.; Knecht, A.; Köster, U.; Kraev, I. S.; Porobic, T.; Prashanth, P. N.; Towner, I. S.; Tramm, C.; Zákoucký, D.; Severijns, N.

2014-09-01

321

Fourier transform infrared spectroscopic and theoretical study of water interactions with glycine and its N-methylated derivatives.  

PubMed

In this study we attempt to explain the molecular aspects of amino acids' hydration. Glycine and its N-methylated derivatives: N-methylglycine, N,N-dimethylglycine, and N,N,N-trimethylglycine were used as model solutes in aqueous solution, applying FT-IR spectroscopy as the experimental method. The quantitative version of the difference spectra method enabled us to obtain the solute-affected HDO spectra as probes of influenced water. The spectral results were confronted with density functional theory calculated structures of small hydration complexes of the solutes using the polarizable continuum model. It appears that the hydration of amino acids in the zwitterionic form can be understood allowing a synchronized fluctuation of hydrogen bonding between the solute and the water molecules. This effect is caused by a noncooperative interaction of water molecules with electrophilic groups of amino acid and by intramolecular hydrogen bond, allowing proton transfer from the carboxylic to the amine group, accomplishing by the chain of two to four water molecules. As a result, an instantaneous water-induced asymmetry of the carboxylate and the amino group of amino acid molecule is observed and recorded as HDO band splitting. Water molecules interacting with the carboxylate group give component bands at 2543 ± 11 and 2467 ± 15 cm(-1), whereas water molecules interacting with protons of the amine group give rise to the bands at 2611 ± 15 and 2413 ± 12 cm(-1). These hydration effects have not been recognized before and there are reasons to expect their validity for other amino acids. PMID:21428668

Panuszko, Aneta; ?miechowski, Maciej; Stangret, Janusz

2011-03-21

322

Tables and graphs of electron-interaction cross sections from 10 eV to 100 GeV derived from the LLNL Evaluated Electron Data Library (EEDL), Z = 1--100  

SciTech Connect

Energy-dependent evaluated electron interaction cross sections and related parameters are presented for elements H through Fm (Z = 1 to 100). Data are given over the energy range from 10 eV to 100 GeV. Cross sections and average energy deposits are presented in tabulated and graphic form. In addition, ionization cross sections and average energy deposits for each shell are presented in graphic form. This information is derived from the Livermore Evaluated Electron Data Library (EEDL) as of July, 1991.

Perkins, S.T.; Cullen, D.E. (Lawrence Livermore National Lab., CA (United States)); Seltzer, S.M. (National Inst. of Standards and Technology (NML), Gaithersburg, MD (United States). Center for Radiation Research)

1991-11-12

323

Deriving Macropore and Preferential Flow Parameters from Tracer and Time-lapse 3D GPR Experiments at the Plot-Scale  

NASA Astrophysics Data System (ADS)

"Hydrology - a science in which all processes are preferential" (Uhlenbrook, 2006) - as such preferential flow is known and discussed in hydrology since almost three decades. At the same time, preferential flow remains problematic as explicit descriptions are hard to define and upscale and implicit descriptions remain rather case sensitive. Moreover, our techniques to monitor preferential flow and especially flow structures are very limited. We conducted three multi-tracer plot-scale (1m x 1m) sprinkler experiments at a forested hillslope in the Attert Basin in Luxembourg with prevailing geogenic and biogenic preferential flow structures. It was accompanied by a 3D time-lapse GPR (Ground Penetrating Radar) survey covering an area of 3m x 3m. We present the results with special emphasis on the derivation of macropore parameters for further modelling. To do so, we developed an automated analysis of images from excavated Brilliant Blue stained profiles. Additionally, we analyse our time-lapse GPR data with respect to temporal changes and derive 3D strutural information of the preferential flow patterns. Superior to tracers, this high resolution subsurface imaging technique is non-invasive, repeatable and therefore helps to disentangle the dye stained patterns towards process observation. The results of the image analyses and the GPR surveys are compared and referenced to soil moisture monitoring, sampled Bromide profiles and stable isotope signatures. We further discuss implications for joint development of model concepts and observation methods.

Jackisch, Conrad; Allroggen, Niklas; Tronicke, Jens; Zehe, Erwin

2014-05-01

324

Climate parameters of Estonia and the Baltic Sea region derived from the high-resolution reanalysis database BaltAn65+  

NASA Astrophysics Data System (ADS)

The high-resolution reanalysis data-base BaltAn65+ covers the period of 1965-2005. Here, this dataset is used to derive essential climate parameters for the Baltic Sea region and Estonia. In particular, monthly mean temperature and total precipitation are calculated and a trend analysis is performed to analyze the temporal evolution of these climatological parameters during the reanalysis period. Monthly, seasonal, and annual maps of the climate characteristics, including trend maps, are created for the Baltic Sea region. Time series of monthly and annually averaged temperature and precipitation sum are presented over the Baltic Sea and Estonian domains together with fitted linear trends and trend significance analysis. Then, comparison with an observational database is performed to assess the quality of the reanalysis database. Additionally, the time series are compared with official climate normals for the period of 1971-2000, as calculated by the Estonian Environment Agency (EtEA). Findings of other publications in the scientific literature dealing with the climate of similar time period for Estonia and the Baltic Sea region are discussed. The quality of the BaltAn65+ reanalysis is found to be generally good for temperature but weak for precipitation.

Männik, Aarne; Zirk, Marko; Rõõm, Rein; Luhamaa, Andres

2014-09-01

325

Derivative Dispersion Relations  

E-print Network

We discuss some analytical and numerical aspects related to the replacement of integral dispersion relations by derivative relations and also the practical applicability of the derivative approach in the investigation of high-energy elastic hadron-hadron scattering. Making use of a Monopole Pomeron model and singly subtracted integral and derivative dispersion relations, we present the results of fits to the experimental data on the total cross sections and the ratio of the real to the imaginary part of the forward elastic scattering amplitude (proton-proton and antiproton-proton interactions). The emphasis is on the region of low energies and, in particular, we show that once the subtraction constant is used as a free fit parameter the derivative approach is equivalent to the integral approach even below the energy cutoff of the fitted data.

R. F. Avila; M. J. Menon

2004-11-30

326

Interactive Effects of Elevated CO2 Concentration and Irrigation on Photosynthetic Parameters and Yield of Maize in Northeast China  

PubMed Central

Maize is one of the major cultivated crops of China, having a central role in ensuring the food security of the country. There has been a significant increase in studies of maize under interactive effects of elevated CO2 concentration ([CO2]) and other factors, yet the interactive effects of elevated [CO2] and increasing precipitation on maize has remained unclear. In this study, a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed so as to obtain reliable results concerning the later effects. The Open Top Chambers (OTCs) experiment was designed to control contrasting [CO2] i.e., 390, 450 and 550 µmol·mol?1, and the experiment with 15% increasing precipitation levels was also set based on the average monthly precipitation of 5–9 month from 1981 to 2010 and controlled by irrigation. Thus, six treatments, i.e. C550W+15%, C550W0, C450W+15%, C450W0, C390W+15% and C390W0 were included in this study. The results showed that the irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize. Similarly, the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [CO2], but irrigation have a positive effect on increased of them at each [CO2] level, resulting in the water use efficiency (WUE) higher in natural precipitation treatment than irrigation treatment at elevated [CO2] levels. Irradiance-response parameters, e.g., maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were increased under elevated [CO2] and irrigation, and dark respiration (Rd) was increased as well. The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced, resulting in an improved of yield and ear characteristics except axle diameter. The study concluded by reporting that, future elevated [CO2] may favor to maize when coupled with increasing amount of precipitation in Northeast China. PMID:24848097

Meng, Fanchao; Zhang, Jiahua; Yao, Fengmei; Hao, Cui

2014-01-01

327

Effect of tetrahydropyrimidine derivatives on protein-nucleic acids interaction. Type II restriction endonucleases as a model system.  

PubMed

2-Methyl-4-carboxy,5-hydroxy-3,4,5,6-tetrahydropyri- midine (THP(A) or hydroxyectoine) and 2-methyl,4-carboxy-3,4,5, 6-tetrahydropyrimidine (THP(B) or ectoine) are now recognized as ubiquitous bacterial osmoprotectants. To evaluate the impact of tetrahydropyrimidine derivatives (THPs) on protein-DNA interaction and on restriction-modification systems, we have examined their effect on the cleavage of plasmid DNA by 10 type II restriction endonucleases. THP(A) completely arrested the cleavage of plasmid and bacteriophage lambda DNA by EcoRI endonuclease at 0.4 mM and the oligonucleotide (d(CGCGAATTCGCG))2 at about 4.0 mM. THP(B) was 10-fold less effective than THP(A), whereas for betaine and proline, a notable inhibition was observed only at 100 mM. Similar effects of THP(A) were observed for all tested restriction endonucleases, except for SmaI and PvuII, which were inhibited only partially at 50 mM THP(A). No effect of THP(A) on the activity of DNase I, RNase A, and Taq DNA polymerase was noticed. Gel-shift assays showed that THP(A) inhibited the EcoRI-(d(CGCGAATTCGCG))2 complex formation, whereas facilitated diffusion of EcoRI along the DNA was not affected. Methylation of the carboxy group significantly decreased the activity of THPs, suggesting that their zwitterionic character is essential for the inhibition effect. Possible mechanisms of inhibition, the role of THPs in the modulation of the protein-DNA interaction, and the in vivo relevance of the observed phenomena are discussed. PMID:10066745

Malin, G; Iakobashvili, R; Lapidot, A

1999-03-12

328

ODPEVP: A program for computing eigenvalues and eigenfunctions and their first derivatives with respect to the parameter of the parametric self-adjoined Sturm-Liouville problem  

NASA Astrophysics Data System (ADS)

A FORTRAN 77 program is presented for calculating with the given accuracy eigenvalues, eigenfunctions and their first derivatives with respect to the parameter of the parametric self-adjoined Sturm-Liouville problem with the parametric third type boundary conditions on the finite interval. The program calculates also potential matrix elements - integrals of the eigenfunctions multiplied by their first derivatives with respect to the parameter. Eigenvalues and matrix elements computed by the ODPEVP program can be used for solving the bound state and multi-channel scattering problems for a system of the coupled second-order ordinary differential equations with the help of the KANTBP programs [O. Chuluunbaatar, A.A. Gusev, A.G. Abrashkevich, A. Amaya-Tapia, M.S. Kaschiev, S.Y. Larsen, S.I. Vinitsky, Comput. Phys. Commun. 177 (2007) 649-675; O. Chuluunbaatar, A.A. Gusev, S.I. Vinitsky, A.G. Abrashkevich, Comput. Phys. Commun. 179 (2008) 685-693]. As a test desk, the program is applied to the calculation of the potential matrix elements for an integrable 2D-model of three identical particles on a line with pair zero-range potentials, a 3D-model of a hydrogen atom in a homogeneous magnetic field and a hydrogen atom on a three-dimensional sphere. Program summaryProgram title: ODPEVP Catalogue identifier: AEDV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3001 No. of bytes in distributed program, including test data, etc.: 24 195 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Intel Xeon EM64T, Alpha 21264A, AMD Athlon MP, Pentium IV Xeon, Opteron 248, Intel Pentium IV Operating system: OC Linux, Unix AIX 5.3, SunOS 5.8, Solaris, Windows XP RAM: depends on the number and order of finite elements; the number of points; and the number of eigenfunctions required. Test run requires 4 MB Classification: 2.1, 2.4 External routines: GAULEG [3] Nature of problem: The three-dimensional boundary problem for the elliptic partial differential equation with an axial symmetry similar to the Schrödinger equation with the Coulomb and transverse oscillator potentials is reduced to the two-dimensional one. The latter finds wide applications in modeling of photoionization and recombination of oppositively charged particles (positrons, antiprotons) in the magnet-optical trap [4], optical absorption in quantum wells [5], and channeling of likely charged particles in thin doped films [6,7] or neutral atoms and molecules in artificial waveguides or surfaces [8,9]. In the adiabatic approach [10] known in mathematics as Kantorovich method [11] the solution of the two-dimensional elliptic partial differential equation is expanded over basis functions with respect to the fast variable (for example, angular variable) and depended on the slow variable (for example, radial coordinate ) as a parameter. An averaging of the problem by such a basis leads to a system of the second-order ordinary differential equations which contain potential matrix elements and the first-derivative coupling terms (see, e.g., [12,13,14]). The purpose of this paper is to present the finite element method procedure based on the use of high-order accuracy approximations for calculating eigenvalues, eigenfunctions and their first derivatives with respect to the parameter of the parametric self-adjoined Sturm-Liouville problem with the parametric third type boundary conditions on the finite interval. The program developed calculates potential matrix elements - integrals of the eigenfunctions multiplied by their derivatives with respect to the parameter. These matrix elements can be used for solving the bound state and multi-channel scattering problems for a system of the coupled second-order ordinary differential equations with the help of the KANTBP programs [1,2]. Solution method: The parametric se

Chuluunbaatar, O.; Gusev, A. A.; Vinitsky, S. I.; Abrashkevich, A. G.

2009-08-01

329

Detection of ‘best’ positive end-expiratory pressure derived from electrical impedance tomography parameters during a decremental positive end-expiratory pressure trial  

PubMed Central

Introduction This study compares different parameters derived from electrical impedance tomography (EIT) data to define ‘best’ positive end-expiratory pressure (PEEP) during a decremental PEEP trial in mechanically-ventilated patients. ‘Best’ PEEP is regarded as minimal lung collapse and overdistention in order to prevent ventilator-induced lung injury. Methods A decremental PEEP trial (from 15 to 0 cm H2O PEEP in 4 steps) was performed in 12 post-cardiac surgery patients on the ICU. At each PEEP step, EIT measurements were performed and from this data the following were calculated: tidal impedance variation (TIV), regional compliance, ventilation surface area (VSA), center of ventilation (COV), regional ventilation delay (RVD index), global inhomogeneity (GI index), and intratidal gas distribution. From the latter parameter we developed the ITV index as a new homogeneity parameter. The EIT parameters were compared with dynamic compliance and the PaO2/FiO2 ratio. Results Dynamic compliance and the PaO2/FiO2 ratio had the highest value at 10 and 15 cm H2O PEEP, respectively. TIV, regional compliance and VSA had a maximum value at 5 cm H2O PEEP for the non-dependent lung region and a maximal value at 15 cm H2O PEEP for the dependent lung region. GI index showed the lowest value at 10 cm H2O PEEP, whereas for COV and the RVD index this was at 15 cm H2O PEEP. The intratidal gas distribution showed an equal contribution of both lung regions at a specific PEEP level in each patient. Conclusion In post-cardiac surgery patients, the ITV index was comparable with dynamic compliance to indicate ‘best’ PEEP. The ITV index can visualize the PEEP level at which ventilation of the non-dependent region is diminished, indicating overdistention. Additional studies should test whether application of this specific PEEP level leads to better outcome and also confirm these results in patients with acute respiratory distress syndrome. PMID:24887391

2014-01-01

330

Profiling the interaction mechanism of quinoline/quinazoline derivatives as MCHR1 antagonists: an in silico method.  

PubMed

Melanin concentrating hormone receptor 1 (MCHR1), a crucial regulator of energy homeostasis involved in the control of feeding and energy metabolism, is a promising target for treatment of obesity. In the present work, the up-to-date largest set of 181 quinoline/quinazoline derivatives as MCHR1 antagonists was subjected to both ligand- and receptor-based three-dimensional quantitative structure-activity (3D-QSAR) analysis applying comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). The optimal predictable CoMSIA model exhibited significant validity with the cross-validated correlation coefficient (Q²) = 0.509, non-cross-validated correlation coefficient (R²(ncv)) = 0.841 and the predicted correlation coefficient (R²(pred)) = 0.745. In addition, docking studies and molecular dynamics (MD) simulations were carried out for further elucidation of the binding modes of MCHR1 antagonists. MD simulations in both water and lipid bilayer systems were performed. We hope that the obtained models and information may help to provide an insight into the interaction mechanism of MCHR1 antagonists and facilitate the design and optimization of novel antagonists as anti-obesity agents. PMID:25257526

Wu, Mingwei; Li, Yan; Fu, Xinmei; Wang, Jinghui; Zhang, Shuwei; Yang, Ling

2014-01-01

331

Profiling the Interaction Mechanism of Quinoline/Quinazoline Derivatives as MCHR1 Antagonists: An in Silico Method  

PubMed Central

Melanin concentrating hormone receptor 1 (MCHR1), a crucial regulator of energy homeostasis involved in the control of feeding and energy metabolism, is a promising target for treatment of obesity. In the present work, the up-to-date largest set of 181 quinoline/quinazoline derivatives as MCHR1 antagonists was subjected to both ligand- and receptor-based three-dimensional quantitative structure–activity (3D-QSAR) analysis applying comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). The optimal predictable CoMSIA model exhibited significant validity with the cross-validated correlation coefficient (Q2) = 0.509, non-cross-validated correlation coefficient (R2ncv) = 0.841 and the predicted correlation coefficient (R2pred) = 0.745. In addition, docking studies and molecular dynamics (MD) simulations were carried out for further elucidation of the binding modes of MCHR1 antagonists. MD simulations in both water and lipid bilayer systems were performed. We hope that the obtained models and information may help to provide an insight into the interaction mechanism of MCHR1 antagonists and facilitate the design and optimization of novel antagonists as anti-obesity agents. PMID:25257526

Wu, Mingwei; Li, Yan; Fu, Xinmei; Wang, Jinghui; Zhang, Shuwei; Yang, Ling

2014-01-01

332

Interaction of platelet-derived autotaxin with tumor integrin ?V?3 controls metastasis of breast cancer cells to bone.  

PubMed

Autotaxin (ATX), through its lysophospholipase D activity controls physiological levels of lysophosphatidic acid (LPA) in blood. ATX is overexpressed in multiple types of cancers, and together with LPA generated during platelet activation promotes skeletal metastasis of breast cancer. However, the pathophysiological sequelae of regulated interactions between circulating LPA, ATX, and platelets remain undefined in cancer. In this study, we show that ATX is stored in ?-granules of resting human platelets and released upon tumor cell-induced platelet aggregation, leading to the production of LPA. Our in vitro and in vivo experiments using human breast cancer cells that do not express ATX (MDA-MB-231 and MDA-B02) demonstrate that nontumoral ATX controls the early stage of bone colonization by tumor cells. Moreover, expression of a dominant negative integrin ?v?3-?744 or treatment with the anti-human ?v?3 monoclonal antibody LM609, completely abolished binding of ATX to tumor cells, demonstrating the requirement of a fully active integrin ?v?3 in this process. The present results establish a new mechanism for platelet contribution to LPA-dependent metastasis of breast cancer cells, and demonstrate the therapeutic potential of disrupting the binding of nontumor-derived ATX with the tumor cells for the prevention of metastasis. PMID:25277122

Leblanc, Raphael; Lee, Sue-Chin; David, Marion; Bordet, Jean-Claude; Norman, Derek D; Patil, Renukadevi; Miller, Duane; Sahay, Debashish; Ribeiro, Johnny; Clézardin, Philippe; Tigyi, Gabor J; Peyruchaud, Olivier

2014-11-13

333

Requirement for interactions of natural killer T cells and myeloid-derived suppressor cells for transplantation tolerance.  

PubMed

The goal of the study was to elucidate the cellular and molecular mechanisms by which a clinically applicable immune tolerance regimen of combined bone marrow and heart transplants in mice results in mixed chimerism and graft acceptance. The conditioning regimen of lymphoid irradiation and anti-T cell antibodies changed the balance of cells in the lymphoid tissues to create a tolerogenic microenvironment favoring the increase of natural killer T (NKT) cells, CD4(+) CD25(+) regulatory T cells and Gr-1(+) CD11b(+) myeloid-derived suppressor cells (MDSCs), over conventional T cells (Tcons). The depletion of MDSCs abrogated chimerism and tolerance, and add back of these purified cells was restorative. The conditioning regimen activated the MDSCs as judged by the increased expression of arginase-1, IL-4R? and programmed death ligand 1, and the activated cells gained the capacity to suppress the proliferation of Tcons to alloantigens in the mixed leukocyte reaction. MDSC activation was dependent on the presence of host invariant NKT cells. The conditioning regimen polarized the host invariant NKT cells toward IL-4 secretion, and MDSC activation was dependent on IL-4. In conclusion, there was a requirement for MDSCs for chimerism and tolerance, and their suppressive function was dependent on their interactions with NKT cells and IL-4. PMID:25311657

Hongo, D; Tang, X; Baker, J; Engleman, E G; Strober, S

2014-11-01

334

A simultaneous study of ionospheric parameters derived from FORMOSAT-3/COSMIC, GRACE, and CHAMP missions over middle, low, and equatorial latitudes: Comparison with ionosonde data  

NASA Astrophysics Data System (ADS)

Accurate ionospheric modeling efforts are partly restricted by lack of enough reliable ground-based data and the inability to validate the existing space-based data. In this article, we present a first time comprehensive reliability and validation check of ionospheric data derived using the GPS Radio Occultation (RO) Technique (from three separate missions: FORMOSAT-3/COSMIC, GRACE, and CHAMP) by comparing RO data with ionosonde data for low-latitude, equatorial, and midlatitude stations, simultaneously. This paper discusses two main objectives: (a) Determination of the appropriate spatial resolutions for effective RO and ionosonde data comparisons and (b) Estimating the accuracy of the ionospheric parameters derived from RO missions with respect to ionosonde data within the African sector. For the first time, ionospheric parameters retrieved from RO data have been compared (in details) to ionosonde data over the African sector, specifically for the South African midlatitude stations Grahamstown, GR13L (33.3°S, 26.5°E), and Madimbo, MU12K (22.4°S, 30.9°E). For the equatorial and low-latitude regions, data for Fortaleza FZA0M (3.8°S, 38°W), Brazil, and Ascension Islands AS00Q (7.9°S, 14.4°W) was analyzed. A simple but important method to determine the latitudinal and longitudinal range to be used in comparison with ionosonde data has been established. Based on statistical analysis, it is found that 4.5°×4.5°, 3°×3°, and 4°×4° are the approximate suitable spatial resolutions in both latitude and longitude spaces over an ionosonde station for effective comparisons for midlatitude, low-latitude, and equatorial regions, respectively. Appropriate spatial coverage for effective comparisons vary with region and therefore a constant assumption should not be applied on regional/global basis especially if the studies/investigations or modeling extends from middle to low/equatorial latitude zones. For the three latitude regions, COSMIC overestimates the maximum height of the F2 layer (hmF2) and underestimates the maximum electron densities. These results provide a step-by-step basis and motivation for the usage of RO data in ionospheric modeling (especially for models which give average conditions) and characterisation over regions that do not have sufficient ground-based instruments/data.

Habarulema, John Bosco; Katamzi, Zama Thobeka; Yizengaw, Endawoke

2014-09-01

335

The PET-derived tumor-to-blood standard uptake ratio (SUR) is superior to tumor SUV as a surrogate parameter of the metabolic rate of FDG  

PubMed Central

Background The standard uptake value (SUV) approach in oncological positron emission tomography has known shortcomings, all of which affect the reliability of the SUV as a surrogate of the targeted quantity, the metabolic rate of [18F]fluorodeoxyglucose (FDG), Km. Among the shortcomings are time dependence, susceptibility to errors in scanner and dose calibration, insufficient correlation between systemic distribution volume and body weight, and, consequentially, residual inter-study variability of the arterial input function (AIF) despite SUV normalization. Especially the latter turns out to be a crucial factor adversely affecting the correlation between SUV and Km and causing inter-study variations of tumor SUVs that do not reflect actual changes of the metabolic uptake rate. In this work, we propose to replace tumor SUV by the tumor-to-blood standard uptake ratio (SUR) in order to distinctly improve the linear correlation with Km. Methods Assuming irreversible FDG kinetics, SUR can be expected to exhibit a much better linear correlation to Km than SUV. The theoretical derivation for this prediction is given and evaluated in a group of nine patients with liver metastases of colorectal cancer for which 15 fully dynamic investigations were available and Km could thus be derived from conventional Patlak analysis. Results For any fixed time point T at sufficiently late times post injection, the Patlak equation predicts a linear correlation between SUR and Km under the following assumptions: (1) approximate shape invariance (but arbitrary scale) of the AIF across scans/patients and (2) low variability of the apparent distribution volume Vr (the intercept of the Patlak Plot). This prediction - and validity of the underlying assumptions - has been verified in the investigated patient group. Replacing tumor SUVs by SURs does improve the linear correlation of the respective parameter with Km from r = 0.61 to r = 0.98. Conclusions SUR is an easily measurable parameter that is highly correlated to Km. In this respect, it is clearly superior to SUV. Therefore, SUR should be seriously considered as a drop-in replacement for SUV-based approaches. PMID:24267032

2013-01-01

336

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 43, NO. 8, AUGUST 2005 1763 Effects of AirSea Interaction Parameters on Ocean  

E-print Network

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 43, NO. 8, AUGUST 2005 1763 Effects of Air­Sea Interaction Parameters on Ocean Surface Microwave Emission at 10 and 37 GHz Mohammed A. Aziz, Steven C, atmospheric water vapor, cloud liquid water, and sea ice extent and concentration. WindSat also serves as risk

Reising, Steven C.

337

Interactions between butterfly-shaped pulses in the inhomogeneous media  

NASA Astrophysics Data System (ADS)

Pulse interactions affect pulse qualities during the propagation. Interactions between butterfly-shaped pulses are investigated to improve pulse qualities in the inhomogeneous media. In order to describe the interactions between butterfly-shaped pulses, analytic two-soliton solutions are derived. Based on those solutions, influences of corresponding parameters on pulse interactions are discussed. Methods to control the pulse interactions are suggested.

Liu, Wen-Jun; Huang, Long-Gang; Pan, Nan; Lei, Ming

2014-10-01

338

Chlorine Isotope Evidence for Syn-Subduction Modification of Serpentinites by Interaction with Sediment-Derived Fluid  

NASA Astrophysics Data System (ADS)

High-pressure serpentinites and rodingites and high- to ultrahigh-pressure metasedimentary rocks from the Aosta region, Italy, preserve strikingly different chlorine isotope compositions that can be used to constrain the nature of fluid-rock interactions during subduction. Serpentinites and rodingitized gabbroic dikes subducted to 70-80 km have bulk ?37Cl values between -1.6 and +0.9‰ (median= -0.5‰, n=26 plus 5 replicates; one amphibole-vein outlier at -2.9‰). Serpentinite ?37Cl values are positively correlated with Cr ± Cl contents (r2= 0.97 and 0.58) and negatively correlated with CaO (r2=0.72). BSE imaging and X-ray mapping reveal up to three generations of compositionally distinct serpentine and chlorite in single samples. The youngest generation, which is most abundant, has the lowest chlorine content. Three rodingite samples contain abundant texturally early fluid inclusions. These samples were finely crushed and leached in 18 M? H2O to extract water-soluble chlorides. The leachates, which are assumed to record the compositions of the fluid inclusions, have ?37Cl values that are 0.7-1.5‰ lower than the corresponding bulk rock values. Leachate from the outlier amph-magnesite vein is indistinguishable from the bulk value at -2.7‰. There is almost no overlap between the Cl isotope compositions of HP serp/rod samples and associated HP/UHP metasedimentary rocks. Calcmica schists, diamond-bearing Mn nodules, and impure marbles subducted to >130 km and calcmica schists and Mn crusts transported to 70-80 km have ?37Cl values between -4.5 and -1.5‰ (median= -2.7‰, n=25 plus 7 replicates; two outlier points at -0.5‰). Primary fluid inclusions in the diamondiferous samples contain carbonate- and silicate-bearing aqueous fluids with very low chloride contents (Frezzotti et al., 2011, Nature Geosci). Taken together, these data record a history of progressive modification of serpentinites and rodingites by mixing with low-?37Cl, low-Cl, high-Ca fluids during subduction and metamorphism. Serpentinites with the highest Cr contents have Cl isotopic compositions identical to those of modern seafloor serpentinites (?37Cl=0.2-0.6‰), consistent with primary serpentinization by seawater (e.g., Barnes et al. 2009, Lithos). Low-Cr serpentinites record significant interaction with a Ca-rich fluid that shifted the rocks to lower ?37Cl values and diluted the original Cr and Cl contents. The fluid was likely derived from continuous devolatilization reactions in associated low-?37Cl, calcareous metasedimentary rocks. These data have important implications for models of subduction mass transfer associated with antigorite breakdown. If serpentinites are commonly modified by interaction with metasedimentary fluids prior to antigorite dehydration, chemical signatures imparted during deserpentinization will reflect the integrated history of fluid-rock interaction in the subduction channel rather than an endmember "serpentinite signature". The data further suggest that Cl may be hydrophobic in HP/UHP carbonate-bearing aqueous fluids, resulting in generation of low-Cl fluid during metamorphic devolatilization.

Selverstone, J.; Sharp, Z. D.

2012-12-01

339

Wh-Questions in Child L2 French: Derivational Complexity and Its Interactions with L1 Properties, Length of Exposure, Age of Exposure, and the Input  

ERIC Educational Resources Information Center

This study investigates how derivational complexity interacts with first language (L1) properties, second language (L2) input, age of first exposure to the target language, and length of exposure in child L2 acquisition. We compared elicited production of "wh"-questions in French in two groups of 15 participants each, one with L1 English…

Prévost, Philippe; Strik, Nelleke; Tuller, Laurie

2014-01-01

340

Binding Rather Than Metabolism May Explain the Interaction of Two Food-Grade Lactobacillus Strains with Zearalenone and Its Derivative  -Zearalenol  

Microsoft Academic Search

The interaction between two Fusarium mycotoxins, zearalenone (ZEN) and its derivative ´-zearalenol ( ´-ZOL), with two food-grade strains of Lactobacillus was investigated. The mycotoxins (2 gm l 1 ) were in- cubated with either Lactobacillus rhamnosus strain GG or L. rhamnosus strain LC705. A considerable propor- tion (38 to 46%) of both toxins was recovered from the bacterial pellet, and

Hani El-Nezami; Nektaria Polychronaki; Seppo Salminen; Hannu Mykkanen

2002-01-01

341

The Niemann-Pick C1 and caveolin-1 proteins interact to modulate efflux of low density lipoprotein-derived cholesterol from late endocytic compartments  

PubMed Central

The Niemann-Pick C1 (NPC1) protein has a central role in regulating the efflux of lipoprotein-derived cholesterol from late endosomes/lysosomes and transport to other cellular compartments. Since the NPC1 protein has been shown to regulate the transport of cholesterol to cellular compartments enriched with the ubiquitous cholesterol-binding and transport protein caveolin-1, the present study was performed to determine whether the NPC1 and caveolin-1 proteins interact and function to modulate efflux of low density lipoprotein (LDL)-derived cholesterol from endocytic compartments. To perform these studies, normal human fibroblasts were grown in media with lipoprotein-deficient serum (LPDS) or media with LPDS supplemented with purified human LDL. The results indicated reciprocal co-immunoprecipitation and partial co-localization of the NPC1 and caveolin-1 proteins that was decreased when fibroblasts were grown in media with LDL. Consistent with interaction of the NPC1 and caveolin-1 proteins, a highly conserved caveolin-binding motif was identified within a cytoplasmic loop located adjacent to the sterol-sensing domain (SSD) of the NPC1 protein. To examine the functional relevance of this interaction, fibroblasts were transfected with caveolin-1 siRNA and found to accumulate increased amounts of LDL-derived cholesterol within late endosomes/ lysosomes. Together, this report presents novel results demonstrating that the NPC1 and caveolin-1 proteins interact to modulate efflux of LDL-derived cholesterol from late endocytic compartments.

Jelinek, David; Heidenreich, Randy A.; Orlando, Robert A.; Garver, William S.

2014-01-01

342

Structure of Ca2+-Bound S100A4 and Its Interaction with Peptides Derived from Nonmuscle Myosin-IIA†  

PubMed Central

S100A4, also known as mts1, is a member of the S100 family of Ca2+-binding proteins that is directly involved in tumor invasion and metastasis via interactions with specific protein targets, including nonmuscle myosin-IIA (MIIA). Human S100A4 binds two Ca2+ ions with the typical EF-hand exhibiting an affinity that is nearly 1 order of magnitude tighter than that of the pseudo-EF-hand. To examine how Ca2+ modifies the overall organization and structure of the protein, we determined the 1.7 ? crystal structure of the human Ca2+-S100A4. Ca2+ binding induces a large reorientation of helix 3 in the typical EF-hand. This reorganization exposes a hydrophobic cleft that is comprised of residues from the hinge region, helix 3, and helix 4, which afford specific target recognition and binding. The Ca2+-dependent conformational change is required for S100A4 to bind peptide sequences derived from the C-terminal portion of the MIIA rod with submicromolar affinity. In addition, the level of binding of Ca2+ to both EF-hands increases by 1 order of magnitude in the presence of MIIA. NMR spectroscopy studies demonstrate that following titration with a MIIA peptide, the largest chemical shift perturbations and exchange broadening effects occur for residues in the hydrophobic pocket of Ca2+-S100A4. Most of these residues are not exposed in apo-S100A4 and explain the Ca2+ dependence of formation of the S100A4–MIIA complex. These studies provide the foundation for understanding S100A4 target recognition and may support the development of reagents that interfere with S100A4 function. PMID:18410126

Malashkevich, Vladimir N.; Varney, Kristen M.; Garrett, Sarah C.; Wilder, Paul T.; Knight, David; Charpentier, Thomas H.; Ramagopal, Udupi A.; Almo, Steven C.; Weber, David J.; Bresnick, Anne R.

2008-01-01

343

Structure of Ca2+ -Bound S100A4 and Its Interaction With Peptides Derived from Nonmuscle Myosin-IIA  

SciTech Connect

S100A4, also known as mts1, is a member of the S100 family of Ca2+-binding proteins that is directly involved in tumor invasion and metastasis via interactions with specific protein targets, including nonmuscle myosin-IIA (MIIA). Human S100A4 binds two Ca2+ ions with the typical EF-hand exhibiting an affinity that is nearly 1 order of magnitude tighter than that of the pseudo-EF-hand. To examine how Ca2+ modifies the overall organization and structure of the protein, we determined the 1.7 Angstroms crystal structure of the human Ca2+-S100A4. Ca2+ binding induces a large reorientation of helix 3 in the typical EF-hand. This reorganization exposes a hydrophobic cleft that is comprised of residues from the hinge region, helix 3, and helix 4, which afford specific target recognition and binding. The Ca2+-dependent conformational change is required for S100A4 to bind peptide sequences derived from the C-terminal portion of the MIIA rod with submicromolar affinity. In addition, the level of binding of Ca2+ to both EF-hands increases by 1 order of magnitude in the presence of MIIA. NMR spectroscopy studies demonstrate that following titration with a MIIA peptide, the largest chemical shift perturbations and exchange broadening effects occur for residues in the hydrophobic pocket of Ca2+-S100A4. Most of these residues are not exposed in apo-S100A4 and explain the Ca2+ dependence of formation of the S100A4-MIIA complex. These studies provide the foundation for understanding S100A4 target recognition and may support the development of reagents that interfere with S100A4 function.

Malashkevich,V.; Varney, K.; Garrett, S.; Wilder, P.; Knight, D.; Charpentier, T.; Ramagopal, U.; Almo, S.; Weber, D.; Bresnick, A.

2008-01-01

344

Evaluation of resonance parameters for neutron interaction with iron isotopes for energies up to 400 keV  

SciTech Connect

The evaluation of the resolved resonance parameters of iron isotopes 54, 56, and 57 in the neutron energy region below 400 keV is documented. Estimates of the uncertainties in the resonance parameters and correlation between the partial widths GAMMA/sub n/ and GAMMA/sub ..gamma../ are given when significant. Some details about the procedures used to evaluate the resonance parameters, their uncertainties, and correlations are reported. This evaluation was performed for the general-purpose file of the Evaluated Nuclear Data File (ENDF/B-V MAT 1326). 4 figures, 7 tables.

Perey, C.M.; Perey, F.G.

1980-09-01

345

Parameters of tip-sample interactions in shear mode using a quartz tuning fork AFM with controllable Q-factor  

NASA Astrophysics Data System (ADS)

A quartz tuning fork-based atomic force microscopy for investigating the tip-sample interactions at the nanoscale in the shear-force mode is described. Results of force interactions (damping and elastic forces) can be obtained from the amplitude-phase-distance spectroscopy measurements made with a tuning fork with a tungsten tip and a sample surface. The influence of the interaction between tip and sample using the quality factor as an indicator is investigated. Furthermore, a simple model shows that the extension of a tuning fork-based AFM can be applied to quantitative analysis of the properties of the sample surface.

Thanh Tung, Vo; Chizhik, S. A.; Xuan Hoai, Tran

2009-01-01

346

Titration calorimetric determination of the pairwise interaction parameters of glycerol, D-threitol, mannitol, and D-glucitol in dilute aqueous solutions  

Microsoft Academic Search

Enthalpic pairwise interaction parameters, hjj, were determined by titration calorimetry at 25°C for dilute solutions of glycerol, D-threitol, manitol, and D-glucitol in water. The parameters for these and other polyols conform to the expression hjj (J-kg-1)=145+135nOH-21.5nOH2-41.7dl2-160.5ndlld, where nOH=nC is the number of hydroxyl groups (carbon atoms), ndl is the number of dl configuration of a vicinal pair of OH-groups, and

L. Giorgio Soldi; Yizhak Marcus; Michael J. Blandamer; Paul M. Cullis

1995-01-01

347

Features of parameters of gamma-ray families formed from AA-interactions at superhigh energies above 1016 eV  

NASA Astrophysics Data System (ADS)

Different lateral and energetic characteristics of gamma-ray families produced in nucleus-nucleus (AA) interactions of primary cosmic rays (PCR) are studied. Primary mass composition analysis performed on the basis of "Pamir" Collaboration X-ray emulsion chambers (XREC) data by using of selection criteria of gamma-ray families originating from AA-interactions above 10 PeV. Experimental data are compared with results of MC0 algorithm based on quark-gluon string model (QGSM). Among seven considered variables, only two lateral parameters, R1E and ?, are not described by the MC0 model.

Yuldashbaev, T. S.; Nuritdinov, Kh

2013-02-01

348

Induced fit docking, pharmacophore modeling, and molecular dynamic simulations on thiazolidinedione derivatives to explore key interactions with Tyr48 in polyol pathway.  

PubMed

To obtain a scientific thought and expedition to explore key interactions with Tyr48 in aldose reductase (ALR), combined study of pharmacophore modeling, induced fit docking, and dynamics studies were performed on ALR. A stereo chemically and energetically valid model of ALR-NADP+ complex was developed using homology modeling technique. Statistically a significant five point pharmacophore model was designed on a set of 54 thiazolidinedione derivatives with good external and internal predictive ability. Rigid and induced fit docking protocols were applied on ALR protein for both with and without NADP+ cofactor to identify a suitable binding mode that facilitates the key hydrogen bond interactions with Tyr48. Docking of thiazolidinedione derivatives into ALR-NADP+ complex gave more promising results by reducing false positive binding of inhibitors into the co-factor binding site. Structural changes within Try48 and Asp43 during the binding process in enzyme inhibitor complex were analyzed using molecular dynamics (MD) simulations. The results obtained from dynamic simulations emphasized the role of Tyr48 in maintaining inter or intra molecular hydrogen bond interaction with the protein or inhibitor respectively. New molecules were designed and checked for their binding interactions and showed improved results compared to existing thiazolidinediones derivatives. Hence, these combined protocols will be helpful and cooperative to design and optimize molecules with better inhibitory activity against the biologically active target. PMID:24974084

Vijjulatha, Manga; Lingala, Yamini; Merugu, RaviRaja Tejaswi

2014-07-01

349

Distinct functions of macrophage-derived and cancer cell-derived cathepsin Z combine to promote tumor malignancy via interactions with the extracellular matrix.  

PubMed

During the process of tumor progression, cancer cells can produce the requisite growth- and invasion-promoting factors and can also rely on noncancerous cells in the tumor microenvironment as an alternative, cell-extrinsic source. However, whether the cellular source influences the function of such tumor-promoting factors remains an open question. Here, we examined the roles of the cathepsin Z (CtsZ) protease, which is provided by both cancer cells and macrophages in pancreatic neuroendocrine tumors in humans and mice. We found that tumor proliferation was exclusively regulated by cancer cell-intrinsic functions of CtsZ, whereas tumor invasion required contributions from both macrophages and cancer cells. Interestingly, several of the tumor-promoting functions of CtsZ were not dependent on its described catalytic activity but instead were mediated via the Arg-Gly-Asp (RGD) motif in the enzyme prodomain, which regulated interactions with integrins and the extracellular matrix. Together, these results underscore the complexity of interactions within the tumor microenvironment and indicate that cellular source can indeed impact molecular function. PMID:25274726

Akkari, Leila; Gocheva, Vasilena; Kester, Jemila C; Hunter, Karen E; Quick, Marsha L; Sevenich, Lisa; Wang, Hao-Wei; Peters, Christoph; Tang, Laura H; Klimstra, David S; Reinheckel, Thomas; Joyce, Johanna A

2014-10-01

350

Ethers and esters derived from apocynin avoid the interaction between p47phox and p22phox subunits of NADPH oxidase: evaluation in vitro and in silico  

PubMed Central

NOX (NADPH oxidase) plays an important role during several pathologies because it produces the superoxide anion (O2•?), which reacts with NO (nitric oxide), diminishing its vasodilator effect. Although different isoforms of NOX are expressed in ECs (endothelial cells) of blood vessels, the NOX2 isoform has been considered the principal therapeutic target for vascular diseases because it can be up-regulated by inhibiting the interaction between its p47phox (cytosolic protein) and p22phox (transmembrane protein) subunits. In this research, two ethers, 4-(4-acetyl-2-methoxy-phenoxy)-acetic acid (1) and 4-(4-acetyl-2-methoxy-phenoxy)-butyric acid (2) and two esters, pentanedioic acid mono-(4-acetyl-2-methoxy-phenyl) ester (3) and heptanedioic acid mono-(4-acetyl-2-methoxy-phenyl) ester (4), which are apocynin derivatives were designed, synthesized and evaluated as NOX inhibitors by quantifying O2•? production using EPR (electron paramagnetic resonance) measurements. In addition, the antioxidant activity of apocynin and its derivatives were determined. A docking study was used to identify the interactions between the NOX2?s p47phox subunit and apocynin or its derivatives. The results showed that all of the compounds exhibit inhibitory activity on NOX, being 4 the best derivative. However, neither apocynin nor its derivatives were free radical scavengers. On the other hand, the in silico studies demonstrated that the apocynin and its derivatives were recognized by the polybasic SH3A and SH3B domains, which are regions of p47phox that interact with p22phox. Therefore this experimental and theoretical study suggests that compound 4 could prevent the formation of the complex between p47phox and p22phox without needing to be activated by MPO (myeloperoxidase), this being an advantage over apocynin. PMID:23802190

Macias-Perez, Martha Edith; Martinez-Ramos, Federico; Padilla-Martinez, Itzia Irene; Correa-Basurto, Jose; Kispert, Lowell; Mendieta-Wejebe, Jessica Elena; Rosales-Hernandez, Martha Cecilia

2013-01-01

351

Chirality Effect on Flory-Huggins Interaction Parameters in Polylactide-b-Poly(ethylene-co-1-butene)-b-Polylactide Triblock Copolymers  

NASA Astrophysics Data System (ADS)

In this work, a set of well-defined polylactide-b-poly(ethylene-co-1-butene)-b-polylactide (PLA-PEB-PLA) triblock copolymers were synthesized by controlled ring-opening polymerization of corresponding lactide monomers (L-lactide and racemic mixture of D- and L-lactides) using Sn(Oct)2 as the catalyst. The volume fractions of PLA in the triblock copolymers were adjusted by tuning its molecular weight. The mesophase morphology and phase transitions in these triblock copolymers were studied by temperature-dependent small-angle X-ray scattering (SAXS). The Flory-Huggins interaction parameter ? between EB and lactide as a function of temperature were estimated from the order-disorder transition temperature (TODT) using the mean-field critical (?N)c values. The effects of PLA chirality on both Flory-Huggins interaction parameter and segmental lengths were investigated.

Cao, Weiqiang; Zhu, Lei; Rong, Lixia; Hsiao, Benjamin S.

2009-03-01

352

Computation of energy interaction parameters as well as electric dipole intensity parameters for the absorption spectral study of the interaction of Pr(III) with L-phenylalanine, L-glycine, L-alanine and L-aspartic acid in the presence and absence of Ca 2+ in organic solvents  

NASA Astrophysics Data System (ADS)

Studying the absorption difference and comparative absorption spectra of the interaction of Pr(III) and Nd(III) with L-phenylalanine, L-glycine, L-alanine and L-aspartic acid in the presence and absence of Ca 2+ in organic solvents, various energy interaction parameters like Slater-Condon ( FK), Racah ( Ek), Lande factor ( ?4f), nephelauxetic ratio ( ?), bonding ( b1/2), percentage-covalency ( ?) have been evaluated applying partial and multiple regression analysis. The values of oscillator strength ( P) and Judd-Ofelt electric dipole intensity parameter T? ( ? = 2, 4, 6) for different 4f-4f transitions have been computed. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength ( P) and T? values reveal the mode of binding with different ligands.

Moaienla, T.; Singh, Th. David; Singh, N. Rajmuhon; Devi, M. Indira

2009-10-01

353

In-situ surface wettability parameters of submerged in brackish water surfaces derived from captive bubble contact angle studies as indicators of surface condition level  

NASA Astrophysics Data System (ADS)

The characterization of wetting properties (by contact angles) of several undersea artificial (glass plates,) and natural (stones, sand layers, soft-bottom structures, aquatic macrophytes, sediments, and seafloor communities) solid substrata in the Baltic Sea brackish water (Gulf of Gdansk). The studies were performed under laboratory and field conditions using a novel captive bubble air-pipette computer microscope system. A set of the surface wettability parameters: the apparent surface free energy ?SV, adhesive layer film pressure ?, work of adhesion WA, and work of spreading WS were determined to quantify the wetting properties of model substrata using the contact angle hysteresis (CAH) approach. The useful technique to measure in situ the contact angle giving reproducible and accurate values of CA turned out to be a captive bubble method, for fully hydrated interfacial layers of highly hydrophilic and porous nature met at seabed (Rodrigues-Valverde et al., 2002). CA measurements revealed mostly hydrophilic nature of the studied solid material (CA < 90°) where the presence of adsorbed organic matter layer or crude oil film covering lead to surface hydrophobization (CA?, ?SV ?,WA?, WS more negative). The adhesion of biofouling was correlated both with CAH and the dispersive interaction term ?SVd of the total ?SV. Monitoring of the artificial substrata of the hydrophilic nature with a CA technique can be used to observe the development of the organisms community i.e., microfouling, and to carry out a comprehensive study of surfaces of the submerged macrophytes (Potamogeton lucens in particular). Since aquatic macrophytes can act as bio-indicators of water chemistry their surface wettability may reflect plant surface erosion and organic matter accumulation state being of particular value in biological assessment of ecosystems status.

Pogorzelski, S. J.; Mazurek, A. Z.; Szczepanska, A.

2013-06-01

354

Interaction  

NSDL National Science Digital Library

Set values for the initial position, velocity, and mass of the two particles, and click on the button "Initialize Animation" to play the animation using your specified values. Note, if m or v are too large, the particles may actually pass through one another which will seem a little strange. Note: the interaction between the particles is a "non-contact" interaction, much like the electrostatic force on two charges. Mathematically, it is actually a Hooke's law interaction.

Christian, Wolfgang; Belloni, Mario

2008-02-19

355

Theoretical study of the aqueous solvation of HgCl2: Monte Carlo simulations using second-order Moller-Plesset-derived flexible polarizable interaction potentials  

NASA Astrophysics Data System (ADS)

A study of the solvation of HgCl2 including ab initio aggregates of up to 24 water molecules and the results of extensive Monte Carlo simulations for the liquid phase using MP2-derived interaction potentials is presented. The interaction potentials are flexible, polarizable, and include non-additive effects. We conclude that a cluster description of the solvation mechanism is limited when compared to the condensed phase. The molecular image derived from the MC simulations is peculiar. It resembles that of a hydrophobic solute, which explains the rather easy passage of this neutral molecule through the cell membrane; however, it also shows an intermittent binding of one, two, or three water molecules to HgCl2 in the fashion of a hydrophilic solute.

Hernández-Cobos, J.; Ramírez-Solís, A.; Maron, L.; Ortega-Blake, I.

2012-01-01

356

Characteristic properties of electromagnetic wave interaction with uniaxial absorbing metamaterials: A case of the near-zero axial parameter  

Microsoft Academic Search

An exact solution of the boundary electrodynamic problem for a thin layer of uniaxial absorbing metamaterial characterized by the effective permittivity (permeability) tensor with near-zero values of the axial component is investigated. The parameters of optical anisotropy, absorption, and geometry of the problem are determined when the layer exhibits plane electromagnetic wave reflection and transmission that are selective with respect

E. G. Starodubtsev

2010-01-01

357

What is there in the black box of dark energy: variable cosmological parameters or multiple (interacting) components?  

Microsoft Academic Search

The coincidence problems and other dynamical features of dark energy are studied in cosmological models with variable cosmological parameters and in models with the composite dark energy. It is found that many of the problems usually considered to be cosmological coincidences can be explained or significantly alleviated in the aforementioned models.

J. Grande; J. Solà; H. Stefancic

2007-01-01

358

What is there in the black box of dark energy: variable cosmological parameters or multiple (interacting) components?  

E-print Network

The coincidence problems and other dynamical features of dark energy are studied in cosmological models with variable cosmological parameters and in models with the composite dark energy. It is found that many of the problems usually considered to be cosmological coincidences can be explained or significantly alleviated in the aforementioned models.

Javier Grande; Joan Sola; Hrvoje Stefancic

2007-01-08

359

QSAR of estrogen receptor modulators: exploring selectivity requirements for ER(alpha) versus ER(beta) binding of tetrahydroisoquinoline derivatives using E-state and physicochemical parameters.  

PubMed

Considering importance of developing selective estrogen receptor modulators (SERMs), the present paper explores selectivity requirements of tetrahydroisoquinoline derivatives for binding with ER(alpha) versus ER(beta) receptors using E-state index and physicochemical parameters. The best model [n=21, Q(2)=0.512, R(a)(2)=0.613, R=0.819, F=11.6 (df 3,17)] for ER(alpha) binding data obtained from radioligand binding assay showed importance of C(1), C(15) and lipophilicity (logP) while the best model [n=21, Q(2)=0.768, R(a)(2)=0.796, R=0.904, F=40.1 (df 2,18)] for ER(beta) binding data showed importance of C(1) and molar refractivity (MR). While modeling ER(alpha)/ER(beta) selectivity [n=21, Q(2)=0.695, R(a)(2)=0.739, R=0.882, F=19.8 (df 3,17)], C(1), C(15) and molar refractivity were found to be significant contributors. The data obtained from cellular transcription assay were also modeled. In case of ER(alpha), the best equation involving E-state values of C(1) and C(14) and logP explained 62.1% of the variance while the best equation for ER(beta) involving E-state values of C(1) and C(15) and MR explained 64.6% of the variance of the response variable. In case of ER(alpha)/ER(beta) selectivity, the best equation involving E-state values of O(8), C(14) and N(27) showed 48.3% explained variance, which increased to 63.5% on deletion of single outlier. From the analysis it appears that the nitrogen atom of the aminoethoxyphenyl substituent and 6-hydroxy substituent of the tetrahydroisoquinoline nucleus play important roles for ER(alpha)/ER(beta) selectivity in addition to R(1) and R(2) substituents. PMID:15686893

Mukherjee, Subhendu; Saha, Achintya; Roy, Kunal

2005-02-15

360

Development of New Environment Friendly Natural Colored Preservatives for Wood Surface Dying Derived from Different Tree and Herbaceous Plant Extracts and Determination of Their Color Parameters  

Microsoft Academic Search

In this study, the aim is to derive some water-based wood surface dyes which are extracted from different trees and herbaceous plants. For this purpose, wood specimens were prepared from yellow pine (Pinus sylvestris) and beech (Fagus orientalis). The extracts for dyings were derived from walnut (Juglans regia) shells skins, oleander (Nerium oleander), saffron (Crocus sativus) and madder root (Rubia

Mehmet Emin DURU; Ergün BAYSAL; Ayþen Melda ÇOLAK; Ertan ÖZEN

361

Exfoliation of graphite with triazine derivatives under ball-milling conditions: preparation of few-layer graphene via selective noncovalent interactions.  

PubMed

A ball-milling treatment can be employed to exfoliate graphite through interactions with commercially available melamine under solid conditions. This procedure allows the fast production of relatively large quantities of material with a low presence of defects. The milling treatment can be modulated in order to achieve graphene flakes with different sizes. Once prepared, the graphene samples can be redispersed in organic solvents, water, or culture media, forming stable dispersions that can be used for multiple purposes. In the present work, we have screened electron-rich benzene derivatives along with triazine derivatives in their respective ability to exfoliate graphite. The results suggest that the formation of a hydrogen-bonding network is important for the formation of multipoint interactions with the surfaces of graphene, which can be used for the exfoliation of graphite and the stabilization of graphene in different solvents. Aminotriazine systems were found to be the best partners in the preparation and stabilization of graphene layers in different solvents, while the equivalent benzene derivatives did not show comparable exfoliation ability. Computational studies have also been performed to rationalize the experimental results. The results provide also the basis for further work in the preparation of noncovalently modified graphene, where derivatives of aminotriazines can be designed to form extensive hydrogen-bond 2D networks on the graphene surface with the aim of manipulating their electronic and chemical properties. PMID:24380430

León, Verónica; Rodriguez, Antonio M; Prieto, Pilar; Prato, Maurizio; Vázquez, Ester

2014-01-28

362

Investigation and correlation of physical stability, dissolution behaviour and interaction parameter of amorphous solid dispersions of telmisartan: a drug development perspective.  

PubMed

The aim of this study was to investigate if amorphous solid dispersions of telmisartan, prepared in presence of different polymers, exhibit different structural and thermodynamic characteristics and whether these differences can be correlated to their physical stability (time to crystallisation) and dissolution behaviour. Amorphous samples were prepared by melt quenching. The resulting amorphous materials were characterised using X-ray diffraction, Raman spectroscopy and differential scanning calorimetry. All freshly prepared samples were completely X-ray amorphous (with a halo being the only feature in the diffractograms). The shape of the halos in the diffractograms varied suggesting structural variations in the near order of the molecules between the different amorphous solid dispersions (ASDs). Principal component analysis of the Raman spectra of the various ASD revealed that the samples clustered in the scores plot, again suggesting structural differences due to the presence of different drug-polymer interaction. The ranking of the samples with respect to physical stability and interaction parameter was: ASD of telmisartan:eudragit>ASD of telmisartan:soluplus>ASD of telmisartan:HPMC>ASD of telmisartan:PVP>amorphous telmisartan. The interaction parameter, calculated by using the Flory Huggins theory, showed a good correlation with the experimentally determined stability whereas a weak correlation was found with dissolution behaviour of different ASD. This study showed that correlation of physical stability and dissolution behaviour with calculated interaction parameter is possible for the same amorphous systems prepared by using different polymers. This could aid in selecting the most appropriate polymer for the development of optimised formulations containing amorphous drugs. It can be concluded that ASD prepared by using different polymers have different structural and thermal properties. These differences affect the physical stability and dissolution profiles of the amorphous solids. Thus, choosing the right polymer for preparing ASD is critical for producing materials with desired dissolution profiles and enhanced stability. PMID:23684913

Dukeck, R; Sieger, P; Karmwar, P

2013-07-16

363

A statistical approach to study the interactive effects of process parameters on succinic acid production from Bacteroides fragilis  

Microsoft Academic Search

A statistical approach response surface methodology (RSM) was used to study the production of succinic acid from Bacteroides fragilis. The most influential parameters for succinic acid production obtained through one-at-a-time method were glucose, tryptone, sodium carbonate, inoculum size and incubation period. These resulted in the production of 5.4gL?1 of succinic acid in 48h from B. fragilis under anaerobic conditions. Based

Jasmine Isar; Lata Agarwal; Saurabh Saran; Rekha Kaushik; Rajendra Kumar Saxena

2007-01-01

364

The effects and interactions of fabrication parameters on the properties of selective laser sintered hydroxyapatite polyamide composite biomaterials  

Microsoft Academic Search

Purpose – Hydroxyapatite-polymer composite materials are being researched for the development of low-load bearing implants because of their bioactive and osteoconductive properties, while avoiding modulus mismatch found in homogenous materials. For the direct production of hydroxyapatite-polymer composite implants, selective laser sintering (SLS) has been used and various parameters and their effects on the physical properties (micro and macro morphologies) have

M. M. Savalani; L. Hao; P. M. Dickens; Y. Zhang; K. E. Tanner; R. A. Harris

2012-01-01

365

Modulation and Interaction of Immune-Associated Parameters with Antioxidant in the Immunocytes of Crab Scylla paramamosain Challenged with Lipopolysaccharides  

PubMed Central

Invertebrates are dependent on cellular and humoral immune defences against microbial infection. Scylla paramamosain is an important commercial species, but the fundamental knowledge on its immune defense related to the antioxidant and immune-associated reactions is still lacking. The study was to differentiate the responses of immune-associated parameters of haemolymph components in S. paramamosain when challenged with bacterial lipopolysaccharides (LPSs). The immunostimulating effects of LPS in crab by triggering various immune parameters (phagocytosis, lysozyme, antibacterial activity, phenoloxidase, and the generation of superoxide and nitric oxide) were investigated. Results showed that the generation of free radicals, phenoloxidase, lysozyme and antibacterial activities was significantly increased through the exposure periods. Conversely, total hemocyte count and lysosomal membrane stability decreased significantly as the exposure period extended to 96?h. The relationship between the antioxidant enzymes and immune reactions due to LPS was highly significant. In addition, ROS production was positively correlated with antioxidant showing immediate response of antioxidant defense to the oxyradicals generated. Overall, the study indicated that nonspecific immune components in hemocytes of crab showed active response to the LPS stimulation, and their responses suggested that many immune-associated parameters could be modulated and interrelated with the influence of antioxidants in crustaceans. PMID:21716691

Gopalakrishnan, Singaram; Chen, Fang-Yi; Thilagam, Harikrishnan; Qiao, Kun; Xu, Wan-Fang; Wang, Ke-Jian

2011-01-01

366

Valence electronic structure of AuZn and AuMg alloys derived from a new way of analyzing Auger-parameter shifts  

Microsoft Academic Search

A new model is presented that makes it possible to determine the degree of electron transfer in alloys from measurements of the Auger parameter. This approach is superior to the use of core-ionization-energy shifts in conjunction with a potential model. The Auger parameter does not depend on any reference level, whereas ionization energies measured with respect to the Fermi level

T. Darrah Thomas; Peter Weightman

1986-01-01

367

Ocean wave spectrum properties as derived from quasi-exact computations of nonlinear wave-wave interactions  

Microsoft Academic Search

The estimation of nonlinear wave-wave interactions is one of the central problems in the development of operational and research models for ocean wave prediction. In this paper, we present results obtained with a numerical model based on a quasi-exact computation of the nonlinear wave-wave interactions called the Gaussian quadrature method (GQM) that gives both precise and computationally efficient calculations of

E. Gagnaire-Renou; M. Benoit; P. Forget

2010-01-01

368

Interaction of Hurricane Katrina with Optically Complex Water in the Gulf of Mexico: Interpretation Using Satellite-Derived Inherent Optical Properties and Chlorophyll Concentration  

NASA Astrophysics Data System (ADS)

When Hurricane Katrina passed over southern Florida, Florida Bay and the West Florida Shelf, and into the Gulf of Mexico, empirically derived chl a increases were observed in the Tortugas Gyre circulation feature, and in adjacent waters. Analysis of the empirically derived chl a increase within the gyre has been primarily attributed to initiation of a phytoplankton bloom promoted by nutrients upwelled by Katrina's winds. Detailed analysis of inherent optical properties (IOPs) derived from remotely-sensed radiances, however, indicated the interaction of Katrina with shallow coastal and shelf waters likely entrained waters with higher concentrations of chromophoric dissolved organic matter (CDOM) into the gyre circulation, augmenting the chl a signal. Storm-induced upwelling would also transport optically active CDOM to the surface. Increases in empirically derived chl a in the Florida coastal waters influenced by Katrina's winds were therefore partly due to increased absorption by CDOM. This analysis indicates that elevated empirically derived chl a in hurricane-influenced waters should not be unambiguously attributed to increased phytoplankton productivity, particularly in an optically complex coastal environment.

Lyon, P. E.; Acker, J.; Hoge, F. E.; Shen, S.; Roffer, M.; Gawlikowski, G.

2008-12-01

369

Brain-Derived Neurotrophic Factor/FK506-Binding Protein 5 Genotype by Childhood Trauma Interactions Do Not Impact on Hippocampal Volume and Cognitive Performance  

PubMed Central

In the development of psychotic symptoms, environmental and genetic factors may both play a role. The reported association between childhood trauma and psychotic symptoms could therefore be moderated by single nucleotide polymorphisms (SNPs) associated with the stress response, such as FK506-binding protein 5 (FKBP5) and brain-derived neurotrophic factor (BDNF). Recent studies investigating childhood trauma by SNP interactions have inconsistently found the hippocampus to be a potential target underlying these interactions. Therefore, more detailed modelling of these effects, using appropriate covariates, is required. We examined whether BDNF/FKBP5 and childhood trauma interactions affected two proxies of hippocampal integrity: (i) hippocampal volume and (ii) cognitive performance on a block design (BD) and delayed auditory verbal task (AVLT). We also investigated whether the putative interaction was different for patients with a psychotic disorder (n?=?89) compared to their non-psychotic siblings (n?=?95), in order to elicit possible group-specific protective/vulnerability effects. SNPs were rs9296158, rs4713916, rs992105, rs3800373 (FKBP5) and rs6265 (BDNF). In the combined sample, no BDNF/FKBP5 by childhood trauma interactions were apparent for either outcome, and BDNF/FKBP5 by childhood trauma interactions were not different for patients and siblings. The omission of drug use and alcohol consumption sometimes yielded false positives, greatly affected explained error and influenced p-values. The consistent absence of any significant BDNF/FKBP5 by childhood trauma interactions on assessments of hippocampal integrity suggests that the effect of these interactions on psychotic symptoms is not mediated by hippocampal integrity. The importance of appropriate statistical designs and inclusion of relevant covariates should be carefully considered. PMID:24658422

Hernaus, Dennis; van Winkel, Ruud; Gronenschild, Ed; Habets, Petra; Kenis, Gunter; Marcelis, Machteld; van Os, Jim; Myin-Germeys, Inez; Collip, Dina

2014-01-01

370

[An undesirable drug interaction in horses? Complications which can occur during the administration of coumarin derivatives and phenylbutazone].  

PubMed

A study of the literature was done because of questions asked in a court of justice concerning possible poisoning in a jumper, resulting from administration of both phenylbutazone and a coumarin derivative within a particular period. In view of the mechanisms of action and the pharmacokinetic characteristics of the agents, these forms of combined treatment are also highly inadvisable in horses. PMID:4049359

van Miert, A S

1985-08-15

371

Gene, pathway and network frameworks to identify epistatic interactions of single nucleotide polymorphisms derived from GWAS data  

PubMed Central

Background Interactions among genomic loci (also known as epistasis) have been suggested as one of the potential sources of missing heritability in single locus analysis of genome-wide association studies (GWAS). The computational burden of searching for interactions is compounded by the extremely low threshold for identifying significant p-values due to multiple hypothesis testing corrections. Utilizing prior biological knowledge to restrict the set of candidate SNP pairs to be tested can alleviate this problem, but systematic studies that investigate the relative merits of integrating different biological frameworks and GWAS data have not been conducted. Results We developed four biologically based frameworks to identify pairwise interactions among candidate SNP pairs as follows: (1) for each human protein-coding gene, a set of SNPs associated with that gene was constructed providing a gene-based interaction model, (2) for each known biological pathway, a set of SNPs associated with the genes in the pathway was constructed providing a pathway-based interaction model, (3) a set of SNPs associated with genes in a disease-related subnetwork provides a network-based interaction model, and (4) a framework is based on the function of SNPs. The last approach uses expression SNPs (eSNPs or eQTLs), which are SNPs or loci that have defined effects on the abundance of transcripts of other genes. We constructed pairs of eSNPs and SNPs located in the target genes whose expression is regulated by eSNPs. For all four frameworks the SNP sets were exhaustively tested for pairwise interactions within the sets using a traditional logistic regression model after excluding genes that were previously identified to associate with the trait. Using previously published GWAS data for type 2 diabetes (T2D) and the biologically based pair-wise interaction modeling, we identify twelve genes not seen in the previous single locus analysis. Conclusion We present four approaches to detect interactions associated with complex diseases. The results show our approaches outperform the traditional single locus approaches in detecting genes that previously did not reach significance; the results also provide novel drug targets and biomarkers relevant to the underlying mechanisms of disease. PMID:23281810

2012-01-01

372

The association of fiber quality parameters and lint yield components of the F3 derived F4 progeny of two upland cotton populations  

E-print Network

parameters, determined by high volume instrument, were: micronaire, upper half mean fiber length (UHM), unifon-nity index (UI), fiber strength, and elongation. Within-boll yield components, determined by direct measurements or through calculations included...

Basal, Huseyin

2012-06-07

373

Derivatives of ? 2-pyrazoline-products of 1,5-diaminotetrazole interaction with chalcone: Molecular structure and spectral properties  

NASA Astrophysics Data System (ADS)

1,5-diaminotetrazole at conditions of its interaction with chalcones (1,3-diphenylpropenones) in hot DMF undergoes Dimroth rearrangement to 5-tetrazolylhydrazine, which results in formation of 1-(5-tetrazolyl)-3,5-diaryl-? 2-pyrazolines ( I). Structure of the obtained products was confirmed by their parallel synthesis and X-ray structural analysis. Unusual fluorescence behavior of the tetrazolopyrazolynes in polar solvents was attributed to the dissociation of their highly acidic tetrazole N-H group. The last hypothesis was confirmed at the investigation of the protolytic interactions of I with tertiary amine.

Kolos, N. N.; Paponov, B. V.; Orlov, V. D.; Lvovskaya, M. I.; Doroshenko, A. O.; Shishkin, O. V.

2006-03-01

374

Experimental study of sharp and blunt nose streamwise corners at Mach 20. [hypersonic shock-boundary layer interaction parameters  

NASA Technical Reports Server (NTRS)

Extensive heat transfer and pressure distribution data and oil flow studies on sharp and blunt-nose streamwise corners at Mach 20 in helium are presented. The far corner boundary layers on the wedge surfaces forming the corners are laminar for most test conditions. Analysis of the data indicates that the corner flow field geometry can be described in terms of the inviscid shock pattern on the two dimensional surfaces forming the corner. Parameters used to correlate blunt shock growth can be used to correlate features of the flow field observed in oil flow photographs in addition to the measured pressure and heat transfer distributions on the models. The flow field structure is described from available experimental data. Regions of the flow in which the structure still is not known are discussed.

Watson, R. D.

1974-01-01

375

D77, one benzoic acid derivative, functions as a novel anti-HIV-1 inhibitor targeting the interaction between integrase and cellular LEDGF/p75  

SciTech Connect

Integration of viral-DNA into host chromosome mediated by the viral protein HIV-1 integrase (IN) is an essential step in the HIV-1 life cycle. In this process, Lens epithelium-derived growth factor (LEDGF/p75) is discovered to function as a cellular co-factor for integration. Since LEDGF/p75 plays an important role in HIV integration, disruption of the LEDGF/p75 interaction with IN has provided a special interest for anti-HIV agent discovery. In this work, we reported that a benzoic acid derivative, 4-[(5-bromo-4-{l_brace}[2,4-dioxo-3-(2-oxo-2-phenylethyl) -1,3-thiazolidin-5-ylidene]methyl{r_brace}-2-ethoxyphenoxy)methyl]benzoic acid (D77) could potently inhibit the IN-LEDGF/p75 interaction and affect the HIV-1 IN nuclear distribution thus exhibiting antiretroviral activity. Molecular docking with site-directed mutagenesis analysis and surface plasmon resonance (SPR) binding assays has clarified possible binding mode of D77 against HIV-1 integrase. As the firstly discovered small molecular compound targeting HIV-1 integrase interaction with LEDGF/p75, D77 might supply useful structural information for further anti-HIV agent discovery.

Du Li [Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203 (China); Zhao Yaxue [School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China); Chen, Jing [Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203 (China); Yang Liumeng; Zheng Yongtang [Laboratory of Molecular Immunopharmacology, Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223 (China); Tang Yun [School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China)], E-mail: ytang234@ecust.edu.cn; Shen Xu [Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203 (China); School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China)], E-mail: xshen@mail.shcnc.ac.cn; Jiang Hualiang [Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203 (China); School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China)

2008-10-10

376

Muon fluxes derived from the directly measured primary cosmic-ray elemental spectra using hadron-proton machine interaction results.  

NASA Astrophysics Data System (ADS)

The directly measured elemental spectra of primary cosmic rays obtained from JACEE, MSU, SOKOL and CRN data on p, He, CNO, Ne-S and Fe fluxes have been considered for the calculation of elemental nucleon spectra at the top of the atmosphere. Treating these spectra as parents of the secondary mesons, the sea-level muon fluxes at zenith angles 0° and 89° from each species have been derived using Z-factors based on the FNAL cross-section data for meson production and duly corrected for A-A collisions. The conventional muon spectra at 0° and 89° estimated from the individual elemental spectra and the prompt muon contribution arising from the charmed meson decays have been found comparable with the directly measured muon fluxes. The muon spectra derived from the primary nucleon spectrum with a constant spectral index of value -2.73 are found in approximate agreement with the present results.

Mitra, M.; Pal, P.; Bhattacharyya, D. P.

1997-08-01

377

Peptidelipid interactions of the -hairpin antimicrobial peptide tachyplesin and its linear derivatives from solid-state NMR  

E-print Network

are investigated to gain insight into the mechanism of antimicrobial activity. 31 P and 2 H NMR spectra the structure­activity relationship of membrane destructive antimicrobial peptides is to investigatePeptide­lipid interactions of the -hairpin antimicrobial peptide tachyplesin and its linear

Hong, Mei

378

The Photodimerization of a Cinnamoyl Moiety Derivative in Dilute Solution Based on the Intramolecular Chain Interaction of Gemini Surfactant  

E-print Network

on the Intramolecular Chain Interaction of Gemini Surfactant Haiming Fan, Xiaoming Zhu, Lining Gao, Zichen Li 8, 2008 A Gemini surfactant, sodium N,N-di(4-n-butyloxy cinnamoly)-L-cystine, containing a cinnamoyl. The incorporation of a cinnamoyl moiety into the alkyl chains of Gemini surfactant makes it easy to probe

Huang, Jianbin

379

Auditory evoked responses to binaural beat illusion: Stimulus generation and the derivation of the Binaural Interaction Component (BIC)  

Microsoft Academic Search

Electrophysiological indices of auditory binaural beats illusions are studied using late latency evoked responses. Binaural beats are generated by continuous monaural FM tones with slightly different ascending and descending frequencies lasting about 25 ms presented at 1 sec intervals. Frequency changes are carefully adjusted to avoid any creation of abrupt waveform changes. Binaural Interaction Component (BIC) analysis is used to

Ozcan Ozdamar; Jorge Bohorquez; Todor Mihajloski; Erdem Yavuz; Magdalena Lachowska

2011-01-01

380

THE JOURNAL OF CHEMICAL PHYSICS 141, 064104 (2014) Analytic derivative couplings for spin-flip configuration interaction singles  

E-print Network

these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code-flip configuration interaction singles and spin-flip time-dependent density functional theory Xing Zhang and John M

Herbert, John

381

{alpha}-decay and fusion phenomena in heavy ion collisions using nucleon-nucleon interactions derived from relativistic mean-field theory  

SciTech Connect

Nucleus-nucleus potentials are determined in the framework of the double-folding model for a new microscopic nucleon-nucleon (NN) interaction relativistic mean field-3-Yukawa (R3Y) derived from the popular relativistic mean-field theory Lagrangian, and the results are compared for the use of Michigan-3-Yukawa (M3Y) effective NN interactions. The double-folding potentials so obtained are further taken up in the context of the preformed cluster model (PCM) of Gupta and collaborators and the barrier penetration model to study respectively the ground-state (g.s.) {alpha}-decay and low-energy fusion reactions. In this paper, using PCM, we deduce empirically the {alpha} preformation probability P{sub 0}{sup {alpha}(emp)} from experimental data on a few g.s. {alpha} decays in the trans-lead region. For fusion reactions, two projectile-target systems {sup 12}C+{sup 208}Pb and {sup 16}O+{sup 208}Pb are selected for calculating the barrier energies as well positions, fusion cross sections ({sigma}{sub fus}), and fusion barrier distribution [D(E{sub c.m.})]. The barrier energies and positions change for the R3Y NN interactions in comparison with those of the M3Y NN interactions. We find that in the {alpha}-decay studies the values of P{sub 0}{sup {alpha}(emp)}(R3Y) are similar to those of P{sub 0}{sup {alpha}(emp)}(M3Y). Further, both NN interactions give similar {sigma}{sub fus} values using the Wong formula specifically when the R3Y NN interaction calculated {sigma}{sub fus} values are reduced by 1.5 times, and the results are in agreement with the experimental data for both the systems, especially for the higher energies. Results for D(E{sub c.m.}) are also quite similar for both choices of NN interaction.

Singh, BirBikram; Sahu, B. B.; Patra, S. K. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

2011-06-15

382

Inverse modeling for seawater intrusion in coastal aquifers: Insights about parameter sensitivities, variances, correlations and estimation procedures derived from the Henry problem  

USGS Publications Warehouse

Inverse modeling studies employing data collected from the classic Henry seawater intrusion problem give insight into several important aspects of inverse modeling of seawater intrusion problems and effective measurement strategies for estimation of parameters for seawater intrusion. Despite the simplicity of the Henry problem, it embodies the behavior of a typical seawater intrusion situation in a single aquifer. Data collected from the numerical problem solution are employed without added noise in order to focus on the aspects of inverse modeling strategies dictated by the physics of variable-density flow and solute transport during seawater intrusion. Covariances of model parameters that can be estimated are strongly dependent on the physics. The insights gained from this type of analysis may be directly applied to field problems in the presence of data errors, using standard inverse modeling approaches to deal with uncertainty in data. Covariance analysis of the Henry problem indicates that in order to generally reduce variance of parameter estimates, the ideal places to measure pressure are as far away from the coast as possible, at any depth, and the ideal places to measure concentration are near the bottom of the aquifer between the center of the transition zone and its inland fringe. These observations are located in and near high-sensitivity regions of system parameters, which may be identified in a sensitivity analysis with respect to several parameters. However, both the form of error distribution in the observations and the observation weights impact the spatial sensitivity distributions, and different choices for error distributions or weights can result in significantly different regions of high sensitivity. Thus, in order to design effective sampling networks, the error form and weights must be carefully considered. For the Henry problem, permeability and freshwater inflow can be estimated with low estimation variance from only pressure or only concentration observations. Permeability, freshwater inflow, solute molecular diffusivity, and porosity can be estimated with roughly equivalent confidence using observations of only the logarithm of concentration. Furthermore, covariance analysis allows a logical reduction of the number of estimated parameters for ill-posed inverse seawater intrusion problems. Ill-posed problems may exhibit poor estimation convergence, have a non-unique solution, have multiple minima, or require excessive computational effort, and the condition often occurs when estimating too many or co-dependent parameters. For the Henry problem, such analysis allows selection of the two parameters that control system physics from among all possible system parameters. ?? 2005 Elsevier Ltd. All rights reserved.

Sanz, E.; Voss, C. I.

2006-01-01

383

Quantitative inheritance of crop timing traits in interspecific hybrid Petunia populations and interactions with crop quality parameters.  

PubMed

The leaf unfolding rate (i.e., development rate) and the number of nodes forming prior to floral initiation are 2 factors determining production times for floriculture crops. Wild relative species of the cultivated petunia (Petunia x hybrida Vilm.) that exhibited faster development rates than modern cultivars and may therefore be useful genetic sources to develop cultivars with decreased production time were identified. Three interspecific F(2) families, Petunia exserta Stehmann x P. axillaris (Lam.) Britton et al., P. x hybrida 'Mitchell' x P. axillaris, and P. axillaris x P. integrifolia (Hook.) Schinz & Thell. all exhibited transgressive segregation for development rate and node number below the first flower. Development rate and time to flower segregated independently in all families. Leaf number below the first flower was positively correlated with leaf unfolding rate in all families except P. axillaris x P. integrifolia. Time to flower was positively correlated with flower bud number in the P. x hybrida 'Mitchell' x P. axillaris and P. axillaris x P. integrifolia families only. Based on these results, wild Petunia germplasm should be useful for developing petunia cultivars with reduced crop production times, but some negative effects on crop quality parameters may need to be overcome. PMID:20142456

Warner, Ryan M; Walworth, Aaron E

2010-01-01

384

Interaction of the Vibrio cholerae cytolysin (VCC) with cholesterol, some cholesterol esters, and cholesterol derivatives: a TEM study  

Microsoft Academic Search

The Vibrio cholerae cytolysin (VCC) 63-kDa monomer has been shown to interact in aqueous suspension with cholesterol microcystals to produce a ring\\/pore-like heptameric oligomer ?8nm in outer diameter. Transmission electron microscopy data were produced from cholesterol samples adsorbed to carbon support films, spread across the holes of holey carbon films, and negatively stained with ammonium molybdate. The VCC oligomers initially

J Robin Harris; Sucharit Bhakdi; Ulrich Meissner; Dirk Scheffler; Robert Bittman; Guoqing Li; Alexander Zitzer; Michael Palmer

2002-01-01

385

Micelle bound structure and DNA interaction of brevinin-2-related peptide, an antimicrobial peptide derived from frog skin.  

PubMed

Brevinin-2-related peptide (BR-II), a novel antimicrobial peptide isolated from the skin of frog, Rana septentrionalis, shows a broad spectrum of antimicrobial activity with low haemolytic activity. It has also been shown to have antiviral activity, specifically to protect cells from infection by HIV-1. To understand the active conformation of the BR-II peptide in membranes, we have investigated the interaction of BR-II with the prokaryotic and eukaryotic membrane-mimetic micelles such as sodium dodecylsulfate (SDS) and dodecylphosphocholine (DPC), respectively. The interactions were studied using fluorescence and circular dichroism (CD) spectroscopy. Fluorescence experiments revealed that the N-terminus tryptophan residue of BR-II interacts with the hydrophobic core of the membrane mimicking micelles. The CD results suggest that interactions with membrane-mimetic micelles induce an ?-helix conformation in BR-II. We have also determined the solution structures of BR-II in DPC and SDS micelles using NMR spectroscopy. The structural comparison of BR-II in the presence of SDS and DPC micelles showed significant conformational changes in the residues connecting the N-terminus and C-terminus helices. The ability of BR-II to bind DNA was elucidated by agarose gel retardation and fluorescence experiments. The structural differences of BR-II in zwitterionic versus anionic membrane mimics and the DNA binding ability of BR-II collectively contribute to the general understanding of the pharmacological specificity of this peptide towards prokaryotic and eukaryotic membranes and provide insights into its overall antimicrobial mechanism. PMID:25044683

Bandyopadhyay, Susmita; Ng, Boon Yee; Chong, Charmaine; Lim, Ming Zhen; Gill, Sonia Kiran; Lee, Ke Hui; Sivaraman, J; Chatterjee, Chiradip

2014-10-01

386

Microstructural Parameters of Bone Evaluated Using HR-pQCT Correlate with the DXA-Derived Cortical Index and the Trabecular Bone Score in a Cohort of Randomly Selected Premenopausal Women  

PubMed Central

Background Areal bone mineral density is predictive for fracture risk. Microstructural bone parameters evaluated at the appendicular skeleton by high-resolution peripheral quantitative computed tomography (HR-pQCT) display differences between healthy patients and fracture patients. With the simple geometry of the cortex at the distal tibial diaphysis, a cortical index of the tibia combining material and mechanical properties correlated highly with bone strength ex vivo. The trabecular bone score derived from the scan of the lumbar spine by dual-energy X-ray absorptiometry (DXA) correlated ex vivo with the micro architectural parameters. It is unknown if these microstructural correlations could be made in healthy premenopausal women. Methods Randomly selected women between 20–40 years of age were examined by DXA and HR-pQCT at the standard regions of interest and at customized sub regions to focus on cortical and trabecular parameters of strength separately. For cortical strength, at the distal tibia the volumetric cortical index was calculated directly from HR-pQCT and the areal cortical index was derived from the DXA scan using a Canny threshold-based tool. For trabecular strength, the trabecular bone score was calculated based on the DXA scan of the lumbar spine and was compared with the corresponding parameters derived from the HR-pQCT measurements at radius and tibia. Results Seventy-two healthy women were included (average age 33.8 years, average BMI 23.2 kg/m2). The areal cortical index correlated highly with the volumetric cortical index at the distal tibia (R ?=? 0.798). The trabecular bone score correlated moderately with the microstructural parameters of the trabecular bone. Conclusion This study in randomly selected premenopausal women demonstrated that microstructural parameters of the bone evaluated by HR-pQCT correlated with the DXA derived parameters of skeletal regions containing predominantly cortical or cancellous bone. Whether these indexes are suitable for better predictions of the fracture risk deserves further investigation. PMID:24551194

Popp, Albrecht W.; Buffat, Helene; Eberli, Ursula; Lippuner, Kurt; Ernst, Manuela; Richards, R. Geoff; Stadelmann, Vincent A.; Windolf, Markus

2014-01-01

387

Interaction of iron-copper mixed metal oxide oxygen carriers with simulated synthesis gas derived from steam gasification of coal  

SciTech Connect

The objective of this work was to prepare supported bimetallic Fe–Cu oxygen carriers and to evaluate their performance for the chemical-looping combustion (CLC) process with simulated synthesis gas derived from steam gasification of coal/air. Ten-cycle CLC tests were conducted with Fe–Cu oxygen carriers in an atmospheric thermogravimetric analyzer utilizing simulated synthesis gas derived from the steam gasification of Polish Janina coal and Illinois #6 coal as fuel. The effect of temperature on reaction rates, chemical stability, and oxygen transport capacity were determined. Fractional reduction, fractional oxidation, and global rates of reactions were calculated from the thermogravimetric analysis (TGA) data. The supports greatly affected reaction performance. Data showed that reaction rates and oxygen capacities were stable during the 10-cycle TGA tests for most Fe–Cu/support oxygen carriers. Bimetallic Fe–Cu/support oxygen carriers showed higher reduction rates than Fe-support oxygen carriers. The carriers containing higher Cu content showed better stabilities and better reduction rates. An increase in temperature from 800 °C to 900 °C did not have a significant effect on either the oxygen capacity or the reduction rates with synthesis gas derived from Janina coal. Oxidation reaction was significantly faster than reduction reaction for all supported Fe–Cu oxygen carriers. Carriers with higher Cu content had lower oxidation rates. Ten-cycle TGA data indicated that these oxygen carriers had stable performances at 800–900 °C and might be successfully used up to 900 °C for coal CLC reaction in the presence of steam.

Siriwardane, Ranjani V. [U.S. DOE; Ksepko, Ewelina; Tian, Hanging [URS

2013-01-01

388

Negatome 2.0: a database of non-interacting proteins derived by literature mining, manual annotation and protein structure analysis  

PubMed Central

Knowledge about non-interacting proteins (NIPs) is important for training the algorithms to predict protein–protein interactions (PPIs) and for assessing the false positive rates of PPI detection efforts. We present the second version of Negatome, a database of proteins and protein domains that are unlikely to engage in physical interactions (available online at http://m