These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Derivation of Pitzer Interaction Parameters for an Aqueous Species Pair of FeCitrate- and Mg2+  

NASA Astrophysics Data System (ADS)

The Waste Isolation Pilot Plant (WIPP) is a deep underground repository for the disposal of transuranic (TRU) radioactive waste developed by the U.S. Department of Energy (DOE). The WIPP is located within the bedded salts of the Permian Salado Formation, which consists of interbedded halite and anhydrite layers overlaying the Castile Formation. The waste includes, but is not limited to, the salts of citric acid and iron. To calculate the solution chemistry for brines of WIPP-relevance, WIPP Performance Assessment (PA) employs the Pitzer formulation to determine the activity coefficients of aqueous species in brine. The current WIPP thermodynamic database, however, does not include iron species and their Pitzer parameters, in spite of the fact that there will be a large amount of iron in the WIPP. Iron would be emplaced as part of the waste, as well as the containers for the waste. The objective of this analysis is to derive the Pitzer binary interaction parameters for the pair of Mg2+ and FeCitrate-. Briefly, an aqueous model for dissolution of Fe(OH)2(s) in MgNa2Citrate solution was fitted to the experimentally measured solubility data. The aqueous model consists of several chemical reactions and related Pitzer interaction parameters. Specifically, Pitzer binary interaction parameters for the Mg2+ and FeCitrate- pair (?(0), ?(1), and C?) were fitted to the experimental data. Anoxic gloveboxes were used to keep the oxygen level low (less than 6 ppm) throughout the experiments. Aging time was more than 800 days to ensure equilibrium. EQ3NR packaged in EQ3/6 v.8.0a calculates the aqueous speciation and saturation index using an aqueous model addressed in EQ3/6's database. The saturation index indicates how far the system is from equilibrium with respect to the solid of interest. Thus, the smaller the sum of squared saturation indices that the aqueous model calculates for the given number of experiments, the more closely the model attributes equilibrium to each individual experiment with respect to the solid of interest. The calculation of aqueous speciation and saturation indices was repeated by adjusting ?(0), ?(1), and C? in the database until the values are found that make the sum of squared saturation indices smallest for the given number of experiments. Preliminary results indicated that Mg2+ and FeCitrate- exhibit an insignificant interaction. The interaction of other pairs in the system are being investigated.

Jang, J.; Olivas, T.; Nemer, M.

2013-12-01

2

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

3

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

2008-10-14

4

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

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

An evaluation of VAS-derived severe storm parameters  

NASA Technical Reports Server (NTRS)

The Visible Infrared Spin Scan Radiometer (VISSR) Atmospheric Sounder (VAS) carried by U.S. meteorological satellites in GEO yield sounding parameters applicable to severe local storm forecasting. Discrepancies between VAS and radiosonde parameters are noted to increase with the number of computational steps required. It is found that VAS-derived parameters incorporating observed surface data yield results superior to those of parameters that do not incorporate them. VAS-derived parameters did not represent consistent improvements over 12-hour limited-area fine-mesh model numerical forecasts.

Olson, Steven R.; Fuelberg, Henry E.

1990-01-01

7

Hubble parameter corrected interactions in cosmology  

E-print Network

In this paper we make steps in a new direction by considering fluids with EoS of more general form $F(\\rho,P)=0$. It is thought that there should be interaction between cosmic fluids, but this assumption for this stage carries only phenomenological character opening a room for different kind of manipulations. In this article we will consider a modification of an interaction $Q$, where we accept that interaction parameter $b_{1}$ (order of unity) in $Q=3Hb_{1}\\rho$ is time dependent and presented as a linear function of Hubble parameter $H$ of the form $b_{0}+btH$, where $b$ and $b_{0}$ are constants. We consider two different models include modified Chaplygin gas and palotropic gas which have bulk viscosity. Then, we investigate problem numerically and analyze behavior of different cosmological parameters concerning to fluids and behavior of Universe.

J. Sadeghi; M. Khurshudyan; M. Hakobyan; H. Farahani

2014-03-12

8

Enhancement of parameter estimation by Kerr interaction  

E-print Network

We address quantum estimation of displacement and squeezing parameters by the class of probes made of Gaussian states undergoing Kerr interaction. If we fix the overall energy available to the probe, without posing any constraint on the available Gaussian squeezing, then Gaussian squeezing represents the optimal resource for parameter estimation. On the other hand, in the more realistic case where the amount of Gaussian squeezing is fixed, or even absent, then Kerr interaction turns out to be useful to improve estimation, especially for probe states with large amplitude. Our results indicate that precision achievable with current technology Gaussian squeezing may be attained and surpassed for realistic values of the Kerr coupling.

Marco G. Genoni; Carmen Invernizzi; Matteo G. A. Paris

2009-09-28

9

On the Derivation of Polyurethane Kinetic Parameters Using Genetic Algorithms   

E-print Network

There is a lack of quantification for the kinetics mechanism of polyurethane thermal decomposition. The objective of this work is to derive a set of parameters for the kinetics of polyurethane valid for numerical models, with an emphasis...

Rein, Guillermo; Herren, Jaime; Fernandez-Pello, Carlos; Urban, David

10

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

11

Dark energy model with higher derivative of Hubble parameter  

E-print Network

In this letter we consider a dark energy model in which the energy density is a function of the Hubble parameter $H$ and its derivative with respect to time $\\rho_{de}=3\\alpha \\ddot{H}H^{-1}+3\\beta\\dot{H}+3\\gamma H^2$. The behavior of the dark energy and the expansion history of the Universe depend heavily on the parameters of the model $\\alpha$, $\\beta$ and $\\gamma$. It is very interesting that the age problem of the well-known three old objects can be alleviated in this models.

Songbai Chen; Jiliang Jing

2009-07-16

12

Deriving sea-state parameters using RISAT-1 SAR data  

NASA Astrophysics Data System (ADS)

A technique has been demonstrated for deriving various sea-wave parameters such as peak wavelength, peak direction, and significant wave height from two-dimensional synthetic aperture radar (SAR) data acquired by Indian active microwave remote-sensing satellite RISAT-1 (Radar Imaging Satellite 1). The significant wave height is obtained using the method of azimuth cutoff wavelength, which is the minimum wavelength that can be imaged in the azimuth direction and results due to the roll-off of the SAR image spectra at higher wave numbers. In the present paper, RISAT-1 SAR fine-resolution scan mode intensity image data are used for deriving various wave parameters at a high spatial resolution of 300 m. The changes in wavelength, wave height, and wave direction of sea waves are studied for a coastal wave system using high-resolution sea-wave spectral information. The SAR-derived coastal wave parameters are then compared with JASON-2 altimeter Geophysical Data Record (GDR) products and The European Center for Medium-Range Weather Forecasts (ECMWF)-modeled values, and are found to be in reasonable agreement.

Ganguly, Debojyoti; Mishra, Manoj K.; Chauhan, Prakash

2015-01-01

13

Investigation of solvent effects on UV-vis absorption spectra of dihydroxybenzene derivatives by solvatochromic parameters.  

PubMed

The solvatochromism of dihydroxybenzene derivatives as probes in 18 solvents were investigated in the UV-vis spectra. The position, intensity and shape of absorption bands change with various solvent nature. These changes were rationalized by solvatochromic parameters such as alpha, beta, ET(30), DN and AN using multiple linear regression (MLR) method. The studied dihydroxibenzene derivatives show negative solvatochromism and the correlation coefficients of derived equations by MLR method were obtained in the range 0.974-0.996. The linear solvation energy relationship parameters of the backward regression were applied to the Kamlet and Taft equation for the interaction of these three probes and solvents. The best LSER equation for these three probes, and the LSER parameters of backward regression with their mean effects and the regression coefficient have been calculated. PMID:19264536

Azizi, S N; Chaichi, M J; Yousefi, M

2009-07-01

14

Parameters controlling magnetic interactions in perovskite manganites  

NASA Astrophysics Data System (ADS)

Magnetic superexchange interactions in single-valent perovskites (R,A)MO3 (R,A = Rare and Alkaline Earth's, M = transition metal) are known to dependent on the M-O-M bond angle ? and the interatomic distances through the band-width relation W ~ cos?/n (n ~ 3.5). It was observed previously that TN ~ W2 ~ for RMO3 with M = Cr3+ (t3), Fe3+ (t3e2), and Ni3+ (t6e1) when are constant. We have observed similar dependence for Mn3+ (t3e1). When the bonds were stretched beyond their equilibrium values in mixed-valent La0.5Sr0.5-xBaxMn3.5+O3, a strong suppression of magnetic interactions was observed. In addition, size disorder on the A-site suppressed TN for Sr1-xCaxMn4+O3 because of a local variance of bond angles ??. By removing the effects of stretched bonds and size disorder we have increased Curie temperatures of the layer ordered manganites R1-yBayMnO3. Frequently interesting compounds with ? ~ 180 deg are not possible to obtain due to the limited range of sizes and charges of the A and R ions. Recently, in an attempt to increase the bond angle ? in compounds, which are not possible to obtain through simple A-site substitutions, we have studied the double substituted R- and Mn-site perovskites. Properties of these compounds depend mostly on dilution of the magnetic Mn-O lattice in addition to the previously discussed parameters.

Dabrowski, B.; Mais, J.; Kolesnik, S.; Chmaissem, O.

2011-07-01

15

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

16

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

2009-06-12

17

Terrain classification and derived meteorological parameters for interregional transport models  

NASA Astrophysics Data System (ADS)

A procedure is outlined to incorporate surface characteristics in air pollution models. Deposition velocity, energy exchange and surface roughness are considered, because the knowledge of these parameters is essential in more advanced transport models, which no longer use the Pasquill stability scheme. An estimate of the terrain properties is obtained by inspection of land maps. For this purpose land maps with a scale 1: 250.000 are used. On areas of 10' × 10' (minutes of arc) the following terrain types are distinguished: water, open field, open field with scattered trees and hedges, wood, built-up areas and roads and railways. A procedure is outlined to derive from this classification the surface heat flux, deposition velocity and surface roughness. The method for the surface roughness is compared with a procedure of Smith and Carson (1977, Boundary-Layer Met. 12, 307-330) for the determination of the surface roughness in the United Kingdom.

van Dop, H.

18

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

19

Derivation of Delaware Bay tidal parameters from Space Shuttle photography  

NASA Technical Reports Server (NTRS)

The tide-related parameters of the Delaware Bay are derived from Space Shuttle time-series photographs. The water areas in the bay are measured from interpretation maps of the photographs with a CALCOMP 9100 digitizer and ERDAS Image Processing System. The corresponding tidal levels are calculated using the exposure time annotated on the photographs. From these data, an approximate function relating the water area to the tidal level at a reference point is determined. Based on the function, the water areas of the Delaware Bay at mean high water (MHW) and mean low water (MLW), below 0 m, and for the tidal zone are inferred. With MHW and MLW areas and the mean tidal range, we calculate the tidal influx of the Delaware Bay, which is 2.76 x 10 exp 9 cu m. The velocity of flood tide at the bay mouth is determined using the tidal flux and an integral of the velocity distribution function at the cross section between Cape Henlopen and Cape May. The result is 132 cm/s, which compares well with the data on tidal current charts.

Zheng, Quanan; Yan, Xiao-Hai; Klemas, Vic

1993-01-01

20

Derivation of Delaware Bay tidal parameters from space shuttle photography  

SciTech Connect

The tide-related parameters of the Delaware Bay are derived from space shuttle time-series photographs. The water areas in the bay are measured from interpretation maps of the photographs with a CALCOMP 9100 digitizer and ERDAS Image Processing System. The corresponding tidal levels are calculated using the exposure time annotated on the photographs. From these data, an approximate function relating the water area to the tidal level at a reference point is determined. Based on the function, the water areas of the Delaware Bay at mean high water (MHW) and mean low water (MLW), below 0 m, and for the tidal zone are inferred. With MHW and MLW areas and the mean tidal range, the authors calculate the tidal influx of the Delaware Bay, which is 2.76 x 1O[sup 9] m[sup 3]. Furthermore, the velocity of flood tide at the bay mouth is determined using the tidal flux and an integral of the velocity distribution function at the cross section between Cape Henlopen and Cape May. The result is 132 cm/s, which compares well with the data on tidal current charts.

Zheng, Quanan; Yan, Xiaohai; Klemas, V. (Univ. of Delaware, Newark (United States))

1993-06-01

21

Upscaling water cycle parameters using geomorphometric terrain parameters and topographic indices derived from interferometric DEM  

NASA Astrophysics Data System (ADS)

For assessing a regional water balance in boreal landscapes the extend to which evapo-transpiration is subject to spatial variations needs to be known. Water cycle parameters such as transpiration rates of vegetation are depending on both the vegetation type and hydro-pedologic stand conditions since poor soil drainage respective seasonal soil drought affect water consumption by vegetation. The spatial distribution of the pristine boreal vegetation types can be obtained by SAR or optical remote sensing sensors on a regional scale. Many works have been dealing with this subject in the past and it is widely known how remote sensing can contribute to vegetation mapping. To assess hydro-pedologic stand conditions on a regional scale an alternative method is required. Our approach to resolve this problem is based on the fact that soil water status is essentially a function of topographic properties. For that reason morphometric terrain parameters derived from a Digital Elevation Model (DEM) has been used to indicate regions with homogeneous hydro-pedologic stand conditions, so called "hydropedotopes". To delineate the required hydropedotopes two indicators pertaining to soilwater status and pedo-hydrology were derived from InSAR DEM: (1) The wetness-index and (2) the vertical distance to streams and bottom lines. In a further step the resulting map of hydropedotopes is intersected with a remote sensing derived map of the actual spatial distribution of the boreal vegetation types. This step results in a map which marks out landscape units of homogeneous properties in terms of vegetation type and hydro-pedologic conditions which is the basis for upscaling canopy transpiration measurements. From our approach which uses in addition to conventional remote sensing data the results of an automated digital terrain analysis we expect a substantially enhanced knowledge of the spatial variability of water flux rates conditional on canopy transpiration. The process of our approach at a glance is illustrated.

Etzrodt, N.; Zimmermann, R.; Conrad, O.

2002-01-01

22

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

23

Derivation of four-pole parameters including higher order mode effects for expansion chamber mufflers with extended inlet and outlet  

Microsoft Academic Search

A derivation of the four-pole parameters including higher order mode effects, but with flow-acoustic interactions neglected, is presented for expansion chamber mufflers with extended inlet and outlet. The solution of the problem is based on a standard mode-matching technique. The solution is derived for the general case of straight cylindrical ducts with rigid walls. The end walls in the chamber

M. Åbom

1990-01-01

24

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

25

The QCD Coupling Parameter Derived from the Uncertainty Principle and a Model for Quark Vacuum Fluctuations  

E-print Network

The magnitude of the strong interaction is characterized by $\\alpha_s$, the coupling parameter in Quantum Chromodynamics (QCD), a parameter with an unexplained value in the Standard Model. In this paper, a candidate explanation for $\\alpha_s$ is derived from (1) the lifetime of quark-antiquark pairs in vacuum fluctuations given by the Uncertainty Principle, (2) the variation of $\\alpha_s$ as a function of energy in QCD, and (3) classical relativistic dynamics of the quarks and antiquarks. A semiclassical model for heavy quark-antiquark vacuum fluctuations is described herein, based on (2) and (3). The model in this paper predicts the measured value of $\\alpha_s(M_{Z^0})$ to be 0.121, which is in agreement with recent measurements within statistical uncertainties.

David Batchelor

2010-07-30

26

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

27

Quality assessment parameters for EST-derived SNPs from catfish  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two factors were found to be most significant for validation of EST-derived SNPs: the contig size and the minor allele sequence frequency. The larger the contigs were, the greater the validation rate although the validation rate was reasonably high when the contig sizes were equal to or larger than...

28

AC conductivity parameters of graphene derived from THz etalon transmittance  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

29

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

2014-11-21

30

Aerodynamic Parameters of a UK City Derived from Morphological Data  

NASA Astrophysics Data System (ADS)

Detailed three-dimensional building data and a morphometric model are used to estimate the aerodynamic roughness length z 0 and displacement height d over a major UK city (Leeds). Firstly, using an adaptive grid, the city is divided into neighbourhood regions that are each of a relatively consistent geometry throughout. Secondly, for each neighbourhood, a number of geometric parameters are calculated. Finally, these are used as input into a morphometric model that considers the influence of height variability to predict aerodynamic roughness length and displacement height. Predictions are compared with estimations made using standard tables of aerodynamic parameters. The comparison suggests that the accuracy of plan-area-density based tables is likely to be limited, and that height-based tables of aerodynamic parameters may be more accurate for UK cities. The displacement heights in the standard tables are shown to be lower than the current predictions. The importance of geometric details in determining z 0 and d is then explored. Height variability is observed to greatly increase the predicted values. However, building footprint shape only has a significant influence upon the predictions when height variability is not considered. Finally, we develop simple relations to quantify the influence of height variation upon predicted z 0 and d via the standard deviation of building heights. The difference in these predictions compared to the more complex approach highlights the importance of considering the specific shape of the building-height distributions. Collectively, these results suggest that to accurately predict aerodynamic parameters of real urban areas, height variability must be considered in detail, but it may be acceptable to make simple assumptions about building layout and footprint shape.

Millward-Hopkins, J. T.; Tomlin, A. S.; Ma, L.; Ingham, D. B.; Pourkashanian, M.

2013-03-01

31

Density functional theory studies of Pb (II) interaction with chitosan and its derivatives.  

PubMed

Density functional theory (DFT) studies of Pb (II) ions interaction with biopolymer chitosan and its derivatives are presented. Schiff bases and N-alkylated/arylated derivatives of chitosan were characterized as adsorbents of lead ions and are studied at monomer level. Natural bond orbital (NBO) analysis was carried out for chitosan and derivatives to understand the donor-acceptor interactions. Molecular electrostatic potential (MEP) maps of the adsorbents were plotted with color code. Global reactivity parameters of adsorbents were calculated on the basis of frontier molecular orbital (FMO) energies. Structure of complexes formed between chitosan and derivatives with Pb (II) ion were examined at B3LYP/LanL2DZ level of DFT. The stability of the complexes are discussed based on the values of Eads. We observed that the N-reduced pyridine carboxaldehyde derivative of chitosan (RPC) forms more stable complex with Pb (II) ions than with other derivatves. PMID:25583020

Hassan, Basila; Muraleedharan, K; Abdul Mujeeb, V M

2015-03-01

32

Cloud optical parameters as derived from the multispectral cloud radiometer  

NASA Technical Reports Server (NTRS)

Here, researchers analyze the data taken in the marine stratocumulus intensive field observation component of the First ISCCP Regional Experiment (FIRE), conducted off the California coast in July, 1987 using the Multispectral Cloud Radiometer (MCR). Researchers installed an efficient retrieval scheme for deriving the cloud optical thickness and droplet mode radius, and have described the behavior of the retrieval error. Generally the scheme can retrieve the optical thickness and mode radius adequately unless they are too small; the use of the forward scattering region is more sound than the use of the backscattering portion. Applying the method to real data, researchers derived the two-dimensional distribution of optical thickness and mode radius for a portion of one of the FIRE marine stratocumulus missions. In this case study, the droplet size showed a more uniform distribution than optical thickness with some correlation between large droplet size and small optical thickness. Although researchers can find microphysical reasons for these tendencies, they suspect that the remotely sensed droplet size may be overestimated. As a future problem, they will compare results with in situ data of the droplet size distribution. Also it will be very important to check several reasons why the droplet radius might be overestimated, e.g., soot contamination, effect of escaping photons from the lateral sides of broken clouds, and so on.

Nakajima, Eruyuki; King, Michael D.

1990-01-01

33

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

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. J. van Delden

2007-01-01

35

Effects of rejecting diffusion directions on tensor-derived parameters.  

PubMed

Diffusion Tensor Imaging (DTI) is adversely affected by subject motion. It is necessary to discard the corrupted images before diffusion parameter estimation. However, the consequences of rejecting those images are not well understood. In this study, we investigated the effects of excluding one or more volumes of diffusion weighted images by analyzing the changes in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD) and the primary eigenvector (V1). Based on the full set of diffusion images acquired by the Jones30 diffusion scheme, we generated incomplete sets of at least six in three different ways: random, uniform and clustered rejections. The results showed that MD was not significantly affected by rejecting diffusion directions. In the cases of random rejections, FA, AD, RD and V1 were overestimated more greatly with increasing number of rejections and the overestimations were worse in low FA regions than high FA regions. For uniform rejections, at which the remaining diffusion directions are evenly distributed on a sphere, little change was observed in FA and in V1. Clustered rejections, on the other hand, displayed the most significant overestimation of the parameters, and the resulting accuracy depended on the relative orientation of the underlying fibers with respect to the excluded directions. In practice, if diffusion direction data is excluded, it is important to note the number and location of directions rejected, in order to make a more precise analysis of the data. PMID:25585018

Chen, Yiran; Tymofiyeva, Olga; Hess, Christopher P; Xu, Duan

2015-04-01

36

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

37

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 for the control of weeds in turf grasses at golf courses in Florida. There are concerns about arsenic (As for arsenic species (arsenite, AsIII and arsenate, AsV), dissolved organic matter, and additional constituents

Florida, University of

38

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

39

Derivation of tree stem structural parameters from static terrestrial laser scanning data  

NASA Astrophysics Data System (ADS)

Accurate tree-level characteristic information is increasingly demanded for forest management and environment protection. The cutting-edge remote sensing technique of terrestrial laser scanning (TLS) shows the potential of filling this gap. This study focuses on exploring the methods for deriving various tree stem structural parameters, such as stem position, diameter at breast height (DBH), the degree of stem shrinkage, and the elevation angle and azimuth angle of stem inclination. The data for test was collected with a Leica HDS6100 TLS system in Seurasaari, Southern Finland in September 2010. In the field, the reference positions and DBHs of 100 trees were measured manually. The isolation of individual trees is based on interactive segmentation of point clouds. The estimation of stem position and DBH is based on the schematic of layering and then least-square-based circle fitting in each layer. The slope of robust fit line between the height of each layer and DBH is used to characterize the stem shrinkage. The elevation angle of stem inclination is described by the angle between the ground plane and the fitted stem axis. The angle between the north direction and the fitted stem axis gives the azimuth angle of stem inclination. The estimation of the DBHs performed with R square (R2) of 0.93 and root mean square error (RMSE) of 0.038m.The average angle corresponding to stem shrinkage is -1.86°. The elevation angles of stem inclinations are ranged from 31° to 88.3°. The results have basically validated TLS for deriving multiple structural parameters of stem, which help better grasp tree specialties.

Tian, Wei; Lin, Yi; Liu, Yajing; Niu, Zheng

2014-11-01

40

Synthesis, characterization and DNA interaction studies of new triptycene derivatives  

PubMed Central

Summary A facile and efficient synthesis of a new series of triptycene-based tripods is being reported. Using 2,6,14- or 2,7,14-triaminotriptycenes as synthons, the corresponding triazidotriptycenes were prepared in high yield. Additionally, we report the transformation of 2,6,14- or 2,7,14-triaminotriptycenes to the corresponding ethynyl-substituted triptycenes via their tribromo derivatives. Subsequently, derivatization of ethynyl-substituted triptycenes was studied to yield the respective propiolic acid and ethynylphosphine derivatives. Characterization of the newly functionalized triptycene derivatives and their regioisomers were carried out using FTIR and multinuclear NMR spectroscopy, mass spectrometry, and elemental analyses techniques. The study of the interaction of these trisubstituted triptycenes with various forms of DNA revealed interesting dependency on the functional groups of the triptycene core to initiate damage or conformational changes in DNA. PMID:24991281

Chakraborty, Sourav; Mondal, Snehasish; Kumari, Rina; Bhowmick, Sourav; Das, Prolay

2014-01-01

41

Comparison of Two Optimization Methods to Derive Energy Parameters for Protein Folding: Perceptron and Z Score  

E-print Network

Comparison of Two Optimization Methods to Derive Energy Parameters for Protein Folding: Perceptron on finding, by means of a perceptron learning scheme, energy parameters such that the native conformations distribution (Z- score). Whereas the perceptron method is sensitive mainly to "outlier" (i.e., extremal) decoys

Mirny, Leonid

42

Statistical comparisons between teleradiometer-derived and slide-derived visibility parameters  

SciTech Connect

An automated scanning densitometer system developed to estimate visibility-related parameters from photographic slides was tested in comparison to similar teleradiometric measurements. Parameters such as target-sky contrast, visual range, atmospheric light extinction coefficient, and plume and layered contrast can be estimated using this system; however, only target-sky radiance ratios and standard visual ranges were compared. More than 1600 concurrent densitometer and teleradiometer data pairs from eight National Park Service air quality and visibility monitoring locations in the western US were analyzed using the techniques of correlation, linear regression, average bias and difference calculation, and cumulative frequency distribution generation. Correlation coefficients were good, especially with middle-range camera vistas around 50 km distant. Regression slopes approached unity with intercepts near zero. Average bias introduced into the determination of radiance ratios from slides ranged from near zero to 6%, depending on target distance. Standard visual range data distributions compared favorably at the low end with some minor differences at the high end.

Johnson, C.E.; Malm, W.C.; Persha, G.; Molenar, J.V.; Hein, J.R.

1985-12-01

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

Deriving physical parameters of unresolved star clusters. III. Application to M 31 PHAT clusters  

NASA Astrophysics Data System (ADS)

Context. This study is the third of a series that investigates the degeneracy and stochasticity problems present in the determination of physical parameters such as age, mass, extinction, and metallicity of partially resolved or unresolved star cluster populations situated in external galaxies when using broad-band photometry. Aims: This work tests the derivation of parameters of artificial star clusters using models with fixed and free metallicity for the WFC3+ACS photometric system. Then the method is applied to derive parameters of a sample of 203 star clusters in the Andromeda galaxy observed with the HST. Methods: Following Papers I and II, the star cluster parameters are derived using a large grid of stochastic models that are compared to the observed cluster broad-band integrated WFC3+ACS magnitudes. Results: We derive the age, mass, and extinction of the sample of M 31 star clusters with one fixed metallicity in agreement with previous studies. Using artificial tests we demonstrate the ability of the WFC3+ACS photometric system to derive the metallicity of star clusters. We show that the metallicity derived using photometry of 36 massive M 31 star clusters is in a good agreement with the metallicity previously derived using spectroscopy taken from literature.

de Meulenaer, P.; Narbutis, D.; Mineikis, T.; Vansevi?ius, V.

2015-02-01

45

Tuning Rod-Rod Interactions in Poly(3-alkylthiophene) Derivatives  

NASA Astrophysics Data System (ADS)

Poly(3-alkylthiophene) (P3AT) derivatives are used commonly in polymer semiconducting applications. However, during the coating of P3AT thin films strong intermolecular interactions generally lead to the formation of semiconducting fibers. This prevents the formation of long-range ordered domains and complicates analysis of structure-property relationships in P3AT-containing devices (e.g., organic photovoltaic cells). Here, we show rod-rod interactions can be controlled by rational polythiophene side chain design. The effects of side chain passivation are evidenced by a depressed melting temperature and the presence of a liquid crystalline region. We show also that while the rod-rod interactions are lowered significantly in a polythiophene derivative with a branched side chain relative to straight chain P3ATs, the optoelectronic properties remain approximately constant. Importantly, this reduced melting temperature allows for the real-time evolution of a P3AT crystal structure at room temperature to be monitored on an experimentally convenient time scale. These structural data correlate well with field-effect charge carrier mobility measurements and provide a path for studying the mechanism of ordering in plastic electronics.

Boudouris, Bryan; Ho, Victor; Segalman, Rachel

2011-03-01

46

On consistent kinetic and derivative interactions for gravitons  

NASA Astrophysics Data System (ADS)

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 candidate family of 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

2015-04-01

47

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

48

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

Microsoft Academic Search

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

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

2011-01-01

49

Probing the supersymmetric parameter space by weakly interacting massive particle direct detection  

NASA Astrophysics Data System (ADS)

We discuss to what extent the present experiments of direct search for weakly interacting massive particles (WIMPs), when interpreted in terms of relic neutralinos, probe interesting regions of the supersymmetric parameter space, which are also being progressively explored at accelerators. Our analysis is performed in a number of different supersymmetric schemes. We derive the relevant neutralino cosmological properties, locally and on the average in the universe. We prove that part of the supersymmetric (SUSY) configurations probed by current WIMP experiments entails relic neutralinos of cosmological interest. The main astrophysical and particle physics uncertainties, relevant for a proper comparison between theory and experimental data, are stressed and taken into account.

Bottino, A.; Donato, F.; Fornengo, N.; Scopel, S.

2001-06-01

50

Parameter derivation for an acoustic cloak based on scattering theory and realization with tunable metamaterials  

NASA Astrophysics Data System (ADS)

This work derives the set of acoustic parameters of a metamaterial for an ideal cylindrical cloak through scattering theory. A multilayered cloak with homogeneous isotropic materials is introduced to approximate the ideal cloak. An active metamaterial, consisting of active arrays of acoustic cavities separated by piezo-diaphragms, is addressed to achieve the required parameters for each layer of the multilayered cloak. In particular, with the aid of a multi-control strategy that takes into account the coupling between adjacent cells, the effective parameters for the cloak can be accurately realized.

Shen, Huijie; Wen, Jihong; Païdoussis, Michael P.; Yu, Dianlong; Cai, Li; Wen, Xisen

2013-09-01

51

Deriving physical parameters of unresolved star clusters III. Application to M31 PHAT clusters  

E-print Network

This study is the third of a series that investigates the degeneracy and stochasticity problems present in the determination of physical parameters such as age, mass, extinction, and metallicity of partially resolved or unresolved star cluster populations situated in external galaxies when using broad-band photometry. This work tests the derivation of parameters of artificial star clusters using models with fixed and free metallicity for the WFC3+ACS photometric system. Then the method is applied to derive parameters of a sample of 203 star clusters in the Andromeda galaxy observed with the HST. Following Papers I \\& II, the star cluster parameters are derived using a large grid of stochastic models that are compared to the observed cluster broad-band integrated WFC3+ACS magnitudes. We derive the age, mass, and extinction of the sample of M31 star clusters with one fixed metallicity in agreement with previous studies. Using artificial tests we demonstrate the ability of the WFC3+ACS photometric system to ...

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

2015-01-01

52

Responses of the second derivative of the finger photoplethysmogram indices and hemodynamic parameters to anesthesia induction  

Microsoft Academic Search

The finger photoplethysmogram (PTG) is a non-invasive method for pulse-wave analysis. The second derivative wave of the PTG (SDPTG) enables evaluation of atherosclerosis and cardiovascular aging. Responses of SDPTG indices and hemodynamic parameters to anesthesia induction are unknown. A total of 42 patients aged ?40 years, who may have had atherosclerotic change, and who underwent elective oral surgery, were analyzed.

Atsushi Kohjitani; Masaaki Miyata; Yoko Iwase; Kazuna Sugiyama

2012-01-01

53

Decadal changes in glacier parameters in the Cordillera Blanca, Peru, derived from remote sensing  

E-print Network

Decadal changes in glacier parameters in the Cordillera Blanca, Peru, derived from remote sensing´a Jiro´n Cahuide No. 175 ­ Jesu´s Mari´a, Lima 11, Peru ABSTRACT. We present spatial patterns of glacier fluctuations from the Cordillera Blanca, Peru, (glacier area, terminus elevations, median elevations

54

Mass-based hygroscopicity parameter interaction model and measurement of atmospheric aerosol water uptake  

NASA Astrophysics Data System (ADS)

In this study we derive and apply a mass-based hygroscopicity parameter interaction model for efficient description of concentration-dependent water uptake by atmospheric aerosol particles with complex chemical composition. The model approach builds on the single hygroscopicity parameter model of Petters and Kreidenweis (2007). We introduce an observable mass-based hygroscopicity parameter ?m which can be deconvoluted into a dilute hygroscopicity parameter (?m0) and additional self- and cross-interaction parameters describing non-ideal solution behavior and concentration dependencies of single- and multi-component systems. For reference aerosol samples of sodium chloride and ammonium sulfate, the ?m-interaction model (KIM) captures the experimentally observed concentration and humidity dependence of the hygroscopicity parameter and is in good agreement with an accurate reference model based on the Pitzer ion-interaction approach (Aerosol Inorganic Model, AIM). Experimental results for pure organic particles (malonic acid, levoglucosan) and for mixed organic-inorganic particles (malonic acid - ammonium sulfate) are also well reproduced by KIM, taking into account apparent or equilibrium solubilities for stepwise or gradual deliquescence and efflorescence transitions. The mixed organic-inorganic particles as well as atmospheric aerosol samples exhibit three distinctly different regimes of hygroscopicity: (I) a quasi-eutonic deliquescence & efflorescence regime at low-humidity where substances are just partly dissolved and exist also in a non-dissolved phase, (II) a gradual deliquescence & efflorescence regime at intermediate humidity where different solutes undergo gradual dissolution or solidification in the aqueous phase; and (III) a dilute regime at high humidity where the solutes are fully dissolved approaching their dilute hygroscopicity. For atmospheric aerosol samples collected from boreal rural air and from pristine tropical rainforest air (secondary organic aerosol) we present first mass-based measurements of water uptake over a wide range of relative humidity (1-99.4%) obtained with a new filter-based differential hygroscopicity analyzer (FDHA) technique. For these samples the concentration dependence of ?m can be described by a simple KIM model equation based on observable mass growth factors and a total of only six fit parameters summarizing the combined effects of the dilute hygroscopicity parameters, self- and cross-interaction parameters, and solubilities of all involved chemical components. One of the fit parameters represents ?m0 and can be used to predict critical dry diameters for the activation of cloud condensation nuclei (CCN) as a function of water vapor supersaturation according to Köhler theory. For sodium chloride and ammonium sulfate reference particles as well as for pristine rainforest aerosols consisting mostly of secondary organic matter, we obtained good agreement between the KIM predictions and measurement data of CCN activation. The application of KIM and mass-based measurement techniques shall help to bridge gaps in the current understanding of water uptake by atmospheric aerosols: (1) the gap between hygroscopicity parameters determined by hygroscopic growth measurements under sub-saturated conditions and by CCN activation measurements at water vapor supersaturation, and (2) the gap between the results of simplified single parameter models widely used in atmospheric or climate science and the results of complex multi-parameter ion- and molecule-interaction models frequently used in physical chemistry and solution thermodynamics (e.g., AIM, E-AIM, ADDEM, UNIFAC, AIOMFAC).

Mikhailov, E.; Vlasenko, S.; Rose, D.; Pöschl, U.

2013-01-01

55

New anthracenedione derivatives: interaction with DNA and biological effects.  

PubMed

Two anthracenedione derivatives [1 - (omega - diethylaminopropylamido) - 4 - hydroxy - 9,10 - anthracenedione hydrochloride (I) and 1 - (omega - diethylaminopropylamido) - 2 - methoxy - 4 - hydroxy - 9, 10 - anthracenedione hydrochloride (II)], having an electron-rich planar chromophore and an amino-substituted side chain, have been synthesized. Their binding ability to DNA was investigated by means of spectroscopic, equilibrium dialysis and fluorescence measurements. Their inhibition efficiency on nucleic acid synthesis was also evaluated both in mouse and human cells. Our results indicate that, in comparison with adriamycin, compound I shows a slightly weaker complexation ability to DNA, while compound II interacts with DNA at a substantially lower level. These data match quite well with the biological response on the inhibition of DNA and RNA synthesis exhibited by the above mentioned compounds; in fact compound I is slightly less efficient than adriamycin and about ten times more efficient than compound II. The close relationship between the results of physicochemical and biological studies is discussed. PMID:6191877

Palumbo, M; Antonello, C; Viano, I; Santiano, M; Gia, O; Gastaldi, S; Magno, S M

1983-06-01

56

Derivatives  

NSDL National Science Digital Library

Murray Bourne developed the Interactive Mathematics site while working as a mathematics lecturer at Ngee Ann Polytechnic in Singapore. The site contains numerous mathematics tutorials and resources for students and teachers alike. This specific page is focused on differentiation, or finding derivatives. Bourne walks users through an introduction to differentiation and limits, and then moves on to more specific applications like rate of change, derivatives of polynomials, and differentiating powers of a function. Each topic includes graphs and interactive materials designed to aid users in understanding the presented concepts. The information here is presented in a clear, straightforward manner that is appropriate for introductory and advanced calculus students alike.

Bourne, Murray

57

Mass-based hygroscopicity parameter interaction model and measurement of atmospheric aerosol water uptake  

NASA Astrophysics Data System (ADS)

In this study we derive and apply a mass-based hygroscopicity parameter interaction model for efficient description of concentration-dependent water uptake by atmospheric aerosol particles. The model approach builds on the single hygroscopicity parameter model of Petters and Kreidenweis (2007). We introduce an observable mass-based hygroscopicity parameter ?m, which can be deconvoluted into a dilute intrinsic hygroscopicity parameter (?m,∞) and additional self- and cross-interaction parameters describing non-ideal solution behavior and concentration dependencies of single- and multi-component systems. For sodium chloride, the ?m-interaction model (KIM) captures the observed concentration and humidity dependence of the hygroscopicity parameter and is in good agreement with an accurate reference model based on the Pitzer ion-interaction approach (Aerosol Inorganic Model, AIM). For atmospheric aerosol samples collected from boreal rural air and from pristine tropical rainforest air (secondary organic aerosol) we present first mass-based measurements of water uptake over a wide range of relative humidity (1-99%) obtained with a new filter-based differential hygroscopicity analyzer (FDHA) technique. By application of KIM to the measurement data we can distinguish three different regimes of hygroscopicity in the investigated aerosol samples: (I) A quasi-eutonic regime at low relative humidity (~60% RH) where the solutes co-exist in an aqueous and non-aqueous phase; (II) a gradually deliquescent regime at intermediate humidity (~60%-90% RH) where different solutes undergo gradual dissolution in the aqueous phase; and (III) a dilute regime at high humidity (?90% RH) where the solutes are fully dissolved approaching their dilute intrinsic hygroscopicity. The characteristic features of the three hygroscopicity regimes are similar for both samples, while the RH threshold values vary as expected for samples of different chemical composition. In each regime, the concentration dependence of ?m can be described by a simple KIM model equation based on observable mass growth factors and six fit parameters summarizing the combined effects of the dilute intrinsic hygroscopicity and interaction parameters of all involved chemical components. One of the fit parameters represents ?m,∞ and can be used to predict CCN activation diameters as a function of water vapor supersaturation. For sodium chloride reference particles as well as for pristine rainforest aerosols consisting mostly of secondary organic matter, we obtained good agreement between the predicted and measured critical diameters of CCN activation. The application of KIM and mass-based measurement techniques shall help to bridge gaps in the current understanding of water uptake by atmospheric aerosols: (1) the gap between hygroscopicity parameters determined by HTDMA (hygroscopicity tandem differential mobility analyzer) or FDHA measurements under sub-saturated conditions and by CCN measurements at water vapor supersaturation, and (2) the gap between the results of simplified single parameter models widely used in atmospheric or climate science and the results of complex multi-parameter ion- and molecule-interaction models frequently used in physical chemistry and thermodynamics (AIM, E-AIM, UNIFAC, AIOMFAC etc.).

Mikhailov, E.; Merkulov, V.; Vlasenko, S.; Rose, D.; Pöschl, U.

2011-11-01

58

Structural parameters of 11 faint Galactic globular clusters derived with 2MASS  

E-print Network

The determination of structural parameters of 11 faint Galactic globular clusters that, in most cases, had not been previously studied in this context. The clusters are IC1257, Lynga7, Terzan4, Terzan10, BH176, ESO452-SC11, ESO280-SC08, 2MASS-GC01, 2MASS-GC02, GLIMPSE-C01 and AL3, which are projected not far from the central region of the Galaxy. Field-star contamination is significant in the colour-magnitude diagrams. Stellar radial number-density and surface-brightness profiles are built with 2MASS photometry that, for the present clusters, corresponds basically to giant-branch stars. Field-star decontamination is essential for clusters in dense fields. With decontaminated photometry we also compute the total MV of four such globular clusters, using M4 as a template. King-like functions are fitted to the radial profiles, from which the core, half-light, half-star count and tidal radii are derived, together with the concentration parameter. Parameters derived here are compared to the equivalent ones of other Galactic globular clusters available in the literature. Structural parameters and luminosity of most of the faint globular clusters dealt with in this paper are consistent with those of Palomar-like (low-mass and loose structure) globular clusters. This work helps to improve coverage of the globular cluster parameter space.

C. Bonatto; E. Bica

2007-11-09

59

Structure of p-shell Nuclei with Interactions Derived from Chiral Effective-Field Theory  

NASA Astrophysics Data System (ADS)

Traditional realistic nucleon-nucleon (NN) interactions based on precision fits to 2-body data have not produced high-quality descriptions of light nuclei. Effective-Field theories (EFT) based on chiral-perturbation theory provide a natural scheme to derive inter-nucleon interactions and predict a three-nucleon interaction at next-to-next-to-leading order (N2LO). A key feature of these EFT potentials is a set of parameters; some of which are determined by the EFT NN couplings, while others are chosen to reproduce the binding energies of A=3 and 4 nuclei. We have developed the tools to utilize EFT-based potentials, including the NNN terms, in the ab initio no-core shell model (NCSM). We have also improved our shell-model codes to increase the scope of our calculations with three-nucleon interactions to the point where model spaces up to 6 ? are accessible for all p-shell nuclei. We will show results of large-basis NCSM calculations for light p-shell nuclei, especially masses A =10, 11, 12, 13 and highlight the impact the N2LO TNI and its parameters on their structure. Support from LDRD contract No. 04-ERD-058 and DOE grant SCW0498 is acknowledged.

Ormand, W. E.; Gueorguiev, V. G.; Navratil, P.; Vary, J. P.

2006-04-01

60

QSAR analysis for ADA upon interaction with a series of adenine derivatives as inhibitors.  

PubMed

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 degrees 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 nucleosides as inhibitors is correlated. QSAR analysis has revealed that binding affinity of the adenine nucleosides upon interaction with ADA depends on the molecular volume, dipole moment of the molecule, electric charge around the N1 atom, and the highest of positive charge for the related molecules. PMID:15113027

Moosavi-Movahedi, A A; Safarian, S; Hakimelahi, G H; Ataei, G; Ajloo, D; Panjehpour, S; Riahi, S; Mousavi, M F; Mardanyan, S; Soltani, N; Khalafi-Nezhad, A; Sharghi, H; Moghadamnia, H; Saboury, A A

2004-01-01

61

Interaction of aldehydes derived from lipid peroxidation and membrane proteins  

PubMed Central

A great variety of compounds are formed during lipid peroxidation of polyunsaturated fatty acids of membrane phospholipids. Among them, bioactive aldehydes, such as 4-hydroxyalkenals, malondialdehyde (MDA) and acrolein, have received particular attention since they have been considered as toxic messengers that can propagate and amplify oxidative injury. In the 4-hydroxyalkenal class, 4-hydroxy-2-nonenal (HNE) is the most intensively studied aldehyde, in relation not only to its toxic function, but also to its physiological role. Indeed, HNE can be found at low concentrations in human tissues and plasma and participates in the control of biological processes, such as signal transduction, cell proliferation, and differentiation. Moreover, at low doses, HNE exerts an anti-cancer effect, by inhibiting cell proliferation, angiogenesis, cell adhesion and by inducing differentiation and/or apoptosis in various tumor cell lines. It is very likely that a substantial fraction of the effects observed in cellular responses, induced by HNE and related aldehydes, be mediated by their interaction with proteins, resulting in the formation of covalent adducts or in the modulation of their expression and/or activity. In this review we focus on membrane proteins affected by lipid peroxidation-derived aldehydes, under physiological and pathological conditions. PMID:24027536

Pizzimenti, Stefania; Ciamporcero, Eric; Daga, Martina; Pettazzoni, Piergiorgio; Arcaro, Alessia; Cetrangolo, Gianpaolo; Minelli, Rosalba; Dianzani, Chiara; Lepore, Alessio; Gentile, Fabrizio; Barrera, Giuseppina

2013-01-01

62

Measurement of the binding parameters of annexin derivativeerythrocyte membrane interactions  

E-print Network

to these membranes was studied by titration with proteins and with calcium. Whereas the preaddition of ethylenediaminetetraacetic acid (EDTA) to reaction mixtures totally prevented membrane binding, Ca2+ -dependent binding that became partially Ca2+ independent. Data derived from saturation titration with ANV derivatives poorly fit

Larson-Prior, Linda

63

Watermite Parasitism of Corixidae: Infection Parameters, Larval Mite Growth, Competitive Interaction and Host Response  

E-print Network

from the largest hosts and from single infections. Intraspecific and interspecific competitionWatermite Parasitism of Corixidae: Infection Parameters, Larval Mite Growth, Competitive parasitism of Corixidae:infection parameters, larval mite growth, competitive interaction and host response P

McCarthy, T.K.

64

Physical meaning of kinetics parameter “lifetime” used in the new multi-point reactor kinetics equations derived using Green's function  

Microsoft Academic Search

The reactor kinetics parameter l which is used in the new multi-point reactor kinetics equations derived using Green's function is shown to have a physical meaning of neutron production time which can be calculated by the Monte Carlo method, although the corresponding reactor kinetics parameter used in the conventional one-point reactor kinetics equations derived using an adjoint function as a

Keisuke Kobayashi

1996-01-01

65

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

66

On the relationship between NMR-derived amide order parameters and protein backbone entropy changes.  

PubMed

Molecular dynamics simulations are used to analyze the relationship between NMR-derived squared generalized order parameters of amide NH groups and backbone entropy. Amide order parameters (O(2) NH ) are largely determined by the secondary structure and average values appear unrelated to the overall flexibility of the protein. However, analysis of the more flexible subset (O(2) NH ?parameters, O(2) axis . A calibration curve for backbone entropy vs. O(2) NH is developed, which accounts for both correlations between amide group motions of different residues, and correlations between backbone and side chain motions. This calibration curve can be used with experimental values of O(2) NH changes obtained by NMR relaxation measurements to extract backbone entropy changes, for example, upon ligand binding. In conjunction with our previous calibration for side chain entropy derived from measured O(2) axis values this provides a prescription for determination of the total protein conformational entropy changes from NMR relaxation measurements. Proteins 2015; 83:922-930. © 2015 Wiley Periodicals, Inc. PMID:25739366

Sharp, Kim A; O'Brien, Evan; Kasinath, Vignesh; Wand, A Joshua

2015-05-01

67

Analysis of shallow landslides by morphometry parameters derived from terrestrial laser scanning point clouds  

NASA Astrophysics Data System (ADS)

Erosion by shallow landslides is a widespread and growing phenomenon in mountainous areas. The major consequences are loss of soil and regolith as well as damages on infrastructure and provision of unconsolidated material for secondary processes such as mudflows. In this study we present a concept for extracting morphometry parameters from terrestrial laser scanning (TLS) point clouds in order to investigate the relation between slope surface structure and regolith depth. TLS is used to collect high-resolution point cloud data of an affected slope in the Schmirn Valley (Tyrol, Austria). Regolith depth is considered to be one of the important factors for the development of shallow landslides. However, direct field measurements are labour- and time-consuming. In this study we developed an approach, to investigate the relation between regolith depth and surface morphometry parameters. The reference regolith depth information is derived from lightweight dynamic cone penetrometer tests (DCPT) within the test site. The suggested approach integrates spatial analysis of Geographic Information Systems and point cloud processing algorithms. It will help to enhance the prediction of shallow landslide occurrence by (i) deriving high resolution 3D morphometric parameters and (ii) determining regolith depth with a reasonable effort due to automation. In future we want to be able to contribute with this concept to the detailed modelling of shallow landslide susceptibility on alpine slopes.

Mayr, A.; Rutzinger, M.; Bremer, M.; Wiegand, C.; Kringer, K.; Geitner, C.

2012-04-01

68

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

69

The use of tree derivatives and a sample support parameter for inferring tree systems.  

PubMed

Tree systems have been studied in the theoretical setting as an extension of finite automata. They have been found useful in the practical domain when applied to syntactic pattern recognition. The practical applications of tree systems have motivated the examination of inference techniques for tree grammars and tree automata. In this paper we present a tree automaton inference algorithm which incorporates three concepts-tree derivatives, grammatical expansion, and inferential strength. Tree derivatives are used for comparing tree forms. Grammatical expansion is a feedback mechanism which effectively enlarges the user sample. An inferential strength parameter is input by the user to indicate the amount of support required from the sample for inferences. The algorithm is also applied for inferring finite-state machines. Finally, we address an open problem posed by Joshi and Levy by demonstrating the use of our algorithm for the design of programming languages. PMID:21868999

Levine, B

1982-01-01

70

Use of a weather buoy to derive improved heat and mass balance parameters for Ruapehu Crater Lake  

NASA Astrophysics Data System (ADS)

Heat and mass balance calculations are important for monitoring volcanoes with heated crater lakes, but for these lakes the critical process of evaporation can be substantially affected by the lake's influence on the air mass above it. Measurements in 2010 using a weather station on a buoy floating in Ruapehu Crater Lake enabled us to derive a relation between wind velocity above the lake and that measured at nearby weather stations, as well as providing direct evidence of the effect of the warm lake on the air above it. This supported the use of evaporation equations that allowed for the changing air conditions as incoming air became warmer and wetter from interaction with the lake, so decreasing the overall evaporation rate. Heat and mass balance calculations using these parameters and equations during the period 2003 to early 2007, as Crater Lake filled before it overflowed, confirm the previously observed high ratio of total heat flow to steam volume.

Hurst, Tony; Christenson, Bruce; Cole-Baker, Jeremy

2012-08-01

71

Understanding Variability in the AVIRIS-Derived Parameters from Vegetation Cover  

NASA Technical Reports Server (NTRS)

This project was carried out in two phases, the first was an investigation of the possible sources of variability in the canopy leaf chemistry parameters derived from AVERJS data on a year-to-year basis, and the second was a follow-on effort to improve the atmospheric correction program ATREM as well as to provide support to the community on the use of ATREM. This final report embodies a general review of the results obtained over the life of the contract as well as detailed interim reports and copies of the six papers published in AVIRIS Workshop Proceedings over the last 3 years.

Goetz, Alexander F. H.

2000-01-01

72

Breaking parameter degeneracy in interacting dark energy models from observations  

E-print Network

We study the interacting dark energy model with time varying dark energy equation of state. We examine the stability in the perturbation formalism and the degeneracy among the coupling between dark sectors, the time-dependent dark energy equation of state and dark matter abundance in the cosmic microwave background radiation. Further we discuss the possible ways to break such degeneracy by doing global fitting using the latest observational data and we get a tight constraint on the interaction between dark sectors.

Xu, Xiao-Dong; Wang, Bin

2011-01-01

73

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

74

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

75

Interaction of a calix[4]arene derivative with a DOPC bilayer: biomolecular simulations towards chloride transport.  

PubMed

The ability of a calix[4]arene derivative (CX-1), bearing four protonated NH3(+) groups located in the upper rim and aliphatic tails in the lower rim, to interact with a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) model bilayer and promote transmembrane chloride transport was investigated by molecular dynamics (MD) simulations. Unconstrained MD simulations show that the interaction of CX-1 with DOPC occurs via the NH3(+) groups, which are able to establish electrostatic interactions and multiple hydrogen bonds with the DOPC phosphate groups, while the aliphatic tails point towards the water phase (when CX-1 starts from the water phase) or to the membrane (when CX-1 is initially positioned within the bilayer). The interaction does not induce any relevant perturbation on the biophysical properties of the bilayer system (area per lipid, thickness, and hydration) apart from a systematic increase in the order parameter of the C2 carbon atom of the sn-1 lipid tail, meaning that the bilayer conserves its integrity. Since total internalization of CX-1 was not observed in the unconstrained MD time-scale, constant velocity steered molecular dynamics (SMD) simulations were performed in order to simulate the CX-1 permeation across the bilayer. At pulling velocities lower than 0.0075 nmps(-1), chloride transport was observed. The Potential of Mean Force (PMF), calculated with the weighted histogram analysis method, indicates a barrier of ca. 58kJmol(-1) for this mobile carrier to cross the membrane. PMID:24316169

Costa, Paulo J; Marques, Igor; Félix, Vítor

2014-03-01

76

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

77

Aerosol hygroscopicity parameter derived from the light scattering enhancement factor measurements in the North China Plain  

NASA Astrophysics Data System (ADS)

The relative humidity (RH) dependence of aerosol light scattering is an essential parameter for accurate estimation of the direct radiative forcing induced by aerosol particles. Because of insufficient information on aerosol hygroscopicity in climate models, a more detailed parameterization of hygroscopic growth factors and resulting optical properties with respect to location, time, sources, aerosol chemistry and meteorology are urgently required. In this paper, a retrieval method to calculate the aerosol hygroscopicity parameter, ?, is proposed based on the in situ measured aerosol light scattering enhancement factor, namely f(RH), and particle number size distribution (PNSD) obtained from the HaChi (Haze in China) campaign. Measurements show that f(RH) increases sharply with increasing RH, and that the time variance of f(RH) is much greater at higher RH. A sensitivity analysis reveals that the f(RH) is more sensitive to the aerosol hygroscopicity than PNSD. f(RH) for polluted cases is distinctly higher than that for clean periods at a specific RH. The derived equivalent ?, combined with the PNSD measurements, is applied in the prediction of the cloud condensation nuclei (CCN) number concentration. The predicted CCN number concentration with the derived equivalent ? agrees well with the measured ones, especially at high supersaturations. The proposed calculation algorithm of ? with the f(RH) measurements is demonstrated to be reasonable and can be widely applied.

Chen, J.; Zhao, C. S.; Ma, N.; Yan, P.

2014-08-01

78

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

79

Boundary Element Analysis of Mufflers with AN Improved Method for Deriving the Four-Pole Parameters  

NASA Astrophysics Data System (ADS)

When a muffler is modelled by the boundary element method (BEM), the transmission loss (TL) can be evaluated by either the conventional four-pole method or the recently developed three-point method. The three-point method produces only the transmission loss (TL), and nothing else. On the other hand, the four-pole method has the advantage of retaining the transfer matrix of the muffler, which contains important parameters when the muffler is connected to another muffler or other components in the exhaust system. However, the major drawback of the conventional four-pole method is that it requires two separate boundary element runs due to the two different boundary conditions imposed on the outlet boundary. Therefore, it can take twice as long to get the TL when compared to the more efficient three-point method. In this paper, an improved method to derive the four-pole parameters for use in the BEM is introduced. Although two boundary element runs are still needed at each frequency, the improved method only solves the boundary element matrix once at each frequency. Therefore, it is as efficient as the three-point method. More importantly, the improved method also produces the four-pole parameters. The boundary element analysis is done by the direct mixed-body BEM. Numerical predictions are compared to experimental results for all test cases, including one with a mean flow effect.

Wu, T. W.; Zhang, P.; Cheng, C. Y. R.

1998-11-01

80

On deriving p-mode parameters for inclined solar-like stars  

E-print Network

Thanks to their high quality, new and upcoming asteroseismic observations - with CoRoT, Kepler, and from the ground... - can benefit from the experience gained with helioseismology. We focus in this paper on solar-like oscillations, for which the inclination of the rotation axis is unknown. We present a theoretical study of the errors of p-mode parameters determined by means of a maximum-likelihood estimator, and we also analyze correlations and biases. We have used different, complementary approaches: we have performed either semi-analytical computation of the Hessian matrix, fitting of single mean profiles, or Monte Carlo simulations. We give first analytical approximations for the errors of frequency, inclination and rotational splitting. The determination of the inclination is very challenging for the common case of slow rotators (like the Sun), making difficult the determination of a reliable rotational splitting. Moreover, due to the numerous correlations, biases - more or less significant - can appear in the determination of various parameters in the case of bad inclination fittings, especially when a locking at 90 degrees occurs. This issue concerning inclination locking is also discussed. Nevertheless, the central frequency and some derived parameters such as the total power of the mode are free of such biases.

J. Ballot; T. Appourchaux; T. Toutain; M. Guittet

2008-03-06

81

Photon interaction parameters of dosimetric interest in bone.  

PubMed

The effective atomic numbers (Z(eff)) and electron densities (N(el)) of cortical and compact bone have been computed for total and partial photon interactions (photoelectric absorption, coherent scattering, incoherent scattering, pair production in a nuclear field, pair production in an electronic field, and sum of non-coherent scattering) by computing the molecular, atomic, and electronic cross section in the wide energy range of 1 keV-100 GeV using WinXCom. The variations of effective atomic number and electron density with energy are shown graphically for all photon interactions. The effective atomic numbers (ZPEA(eff)) for photon energy absorption are also calculated from mass energy absorption coefficients in the energy range 1 keV-20 MeV. The kerma values of bone relative to air are also computed. Additionally, computed tomography (CT) numbers of bone for photon interaction and energy absorption are also computed. The computed Z(eff) and N(el) may be useful in choosing a substitute composite material in place of bone. The estimated mass energy absorption coefficient may be used to evaluate dose and determine the surviving fraction (S) for bone. The usefulness of computed data in the simulation of tissue substitutes is also discussed. PMID:22850239

Manjunatha, H C; Rudraswamy, B

2012-09-01

82

A Poor Man's Derivation of Quantum Compass–Heisenberg Interaction: Superexchange Interaction in J–J Coupling Scheme  

NASA Astrophysics Data System (ADS)

The exchange interaction between 5d electrons in t2g orbitals is derived on the basis of the J–J coupling scheme, which is the appropriate basis in the case of a strong spin–orbit interaction. From simple calculations, it is found that the ferromagnetic Ising interaction (quantum compass model) occurs owing to a selection rule of hybridization between ?7 and ?8 orbitals, while the antiferromagnetic Heisenberg interaction appears from the hybridization between ?7 orbitals. It is also found that the ferromagnetic Ising interaction decreases as the spin–orbit interaction increases. Thus, the sign of the exchange interaction changes from the ferromagnetic Ising interaction to antiferromagnetic Heisenberg interaction as the spin–orbit interaction increases.

Matsuura, Hiroyasu; Ogata, Masao

2014-09-01

83

Critical study of the charge transfer parameter for the calculation of interaction energy using the local hard-soft acid-base principle.  

PubMed

Local hard-soft acid-base (HSAB) principle is semiquantitative in nature due to the presence of an ad hoc charge transfer parameter. The accuracy of HSAB principle significantly depends on the definition of this ad hoc parameter. In this paper, for the first time we have introduced the second-order approximation of ?N (?Nsecond) as an ad hoc parameter for charge transfer to calculate interaction energies of multiple site based interactions using local hard soft acid base principle. The second-order approximation of ?N has been derived from Sanderson's electronegativity equalization principle. To validate our approach, we have studied interaction energies of some prototype molecules. The interaction energies obtained from our approach have been further compared with the interaction energies of those obtained using other charge transfer parameters (?Nfirst and ?) and the conventional methods. We have also discussed the advantages and limitations of the approach. PMID:24066610

Das, Susanta; Shedge, Sapana V; Pal, Sourav

2013-10-24

84

On the Dynamics of Dark Energy with Higher Time Derivatives of Hubble Parameter in El-Nabulsi Fractional Action Cosmology  

NASA Astrophysics Data System (ADS)

In this work, we discussed a new dark energy density model which contains one term proportional to the Hubble parameter H squared, one to the first and one to second time derivative of the Hubble parameter H based on El-Nabulsi fractional action cosmology (FAC). Some cosmological parameters, like the Hubble parameter, the Equation of State (EoS) parameter ? DE and the deceleration parameter q have been reconstructed and studied. Finally, through a test made using the squared speed of sound vs2, the proposed reconstruction model results to be classically unstable.

Pasqua, Antonio; Chattopadhyay, Surajit

2013-09-01

85

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

86

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

87

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

88

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

89

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

NASA Astrophysics Data System (ADS)

Land 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

90

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

91

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

SciTech Connect

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, Hongyi; Huang, Maoyi; Ali, Melkamu; Leng, Guoyong; Leung, Lai-Yung R.; Wang, Shaowen; Sivapalan, Murugesu

2014-07-21

92

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

93

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

SciTech Connect

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 m{sup 2}/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.; Stipp, S. L. S. [Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø (Denmark); Suhonen, H. [European Synchrotron Research Facility, Grenoble (France); Feidenhans'l, R. [Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø (Denmark); Engstrøm, F. [Mærsk Oil and Gas A/S, Copenhagen K (Denmark)

2014-07-28

94

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

95

Poromechanics Parameters of Fluid-Saturated Chemically Active Fibrous Media Derived from a Micromechanical Approach  

PubMed Central

The authors have derived macroscale poromechanics parameters for chemically active saturated fibrous media by combining microstructure-based homogenization with Hill's volume averaging. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's Lemmas. The advantage of this approach is that the resultant continuum model assumes a form suited to study porous materials, while retaining the effect of discrete fiber deformation. As a result, the model is able to predict the influence of microscale phenomena such as fiber buckling on the overall behavior, and in particular, on the poromechanics constants. The significance of the approach is demonstrated using the effect of drainage and fiber nonlinearity on monotonic compressive stress-strain behavior. The model predictions conform to the experimental observations for articular cartilage. The method can potentially be extended to other porous materials such as bone, clays, foams, and concrete. PMID:25419475

Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

2014-01-01

96

Reference values for volumetric capnography-derived non-invasive parameters in healthy individuals.  

PubMed

The aim of this study was to determine typical values for non-invasive volumetric capnography (VCap) parameters for healthy volunteers and anesthetized individuals. VCap was obtained by a capnograph connected to the airway opening. We prospectively studied 33 healthy volunteers 32 ± 6 years of age weighing 70 ± 13 kg at a height of 171 ± 11 cm in the supine position. Data from these volunteers were compared with a cohort of similar healthy anesthetized patients ventilated with the following settings: tidal volume (VT) of 6-8 mL/kg, respiratory rate 10-15 bpm, PEEP of 5-6 cmH?O and FiO? of 0.5. Volunteers showed better clearance of CO? compared to anesthetized patients as indicated by (median and interquartile range): (1) an increased elimination of CO? per mL of VT of 0.028 (0.005) in volunteers versus 0.023 (0.003) in anesthetized patients, p < 0.05; (2) a lower normalized slope of phase III of 0.26 (0.17) in volunteers versus 0.39 (0.38) in anesthetized patients, p < 0.05; and (3) a lower Bohr dead space ratio of 0.23 (0.05) in volunteers versus 0.28 (0.05) in anesthetized patients, p < 0.05. This study presents reference values for non-invasive volumetric capnography-derived parameters in healthy individuals. Mechanical ventilation and anesthesia altered these values significantly. PMID:23389294

Tusman, Gerardo; Gogniat, Emiliano; Bohm, Stephan H; Scandurra, Adriana; Suarez-Sipmann, Fernando; Torroba, Agustin; Casella, Federico; Giannasi, Sergio; Roman, Eduardo San

2013-06-01

97

Derivation of hydrous pyrolysis kinetic parameters from open-system pyrolysis  

NASA Astrophysics Data System (ADS)

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 in open-system pyrolysis to geological conditions may be questionable. Recent study of Lewan and Ruble shows hydrous-pyrolysis conditions can simulate the natural conditions better and its applications are supported by two case studies with natural thermal-burial histories. Nevertheless, performing hydrous pyrolysis experiment is really tedious and requires large amount of sample, while open-system pyrolysis is rather convenient and efficient. Therefore, the present study aims at the derivation of convincing distributed hydrous pyrolysis Ea with only routine open-system Rock-Eval data. Our results unveil that there is a good correlation between open-system Rock-Eval parameter Tmax and the activation energy (Ea) derived from hydrous pyrolysis. The hydrous pyrolysis single Ea can be predicted from Tmax based on the correlation, while the frequency factor (A0) is estimated based on the linear relationship between single Ea and log A0. Because the Ea distribution is more rational than single Ea, we modify the predicted single hydrous pyrolysis Ea into distributed Ea by shifting the pattern of Ea distribution from open-system pyrolysis until the weight mean Ea distribution equals to the single hydrous pyrolysis Ea. Moreover, it has been shown that the shape of the Ea distribution is very much alike the shape of Tmax curve. Thus, in case of the absence of open-system Ea distribution, we may use the shape of Tmax curve to get the distributed hydrous pyrolysis Ea. The study offers a new approach as a simple method for obtaining distributed hydrous pyrolysis Ea with only routine open-system Rock-Eval data, which will allow for better estimating hydrocarbon generation.

Tseng, Yu-Hsin; Huang, Wuu-Liang

2010-05-01

98

Interactive Network Exploration to Derive Insights: Filtering, Clustering,  

E-print Network

transactions, social media communications, etc. (e.g., [14]). These networks represent important scientific, commercial, terrorist, or friendship interactions, where pro-social initiatives, commercial enterprises, or entertainment activities can have profound societal impacts. However, criminals or terrorists may use networks

Golbeck, Jennifer

99

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 ...

100

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

101

The ILIUM forward modelling algorithm for multivariate parameter estimation and its application to derive stellar parameters from Gaia spectrophotometry  

Microsoft Academic Search

I introduce an algorithm for estimating parameters from multidimensional data based on forward modelling. It performs an iterative local search to effectively achieve a non-linear interpolation of a template grid. In contrast to many machine-learning approaches, it avoids fitting an inverse model and the problems associated with this. The algorithm makes explicit use of the sensitivities of the data to

C. A. L. Bailer-Jones

2010-01-01

102

The ILIUM forward modelling algorithm for multivariate parameter estimation and its application to derive stellar parameters from Gaia spectrophotometry  

NASA Astrophysics Data System (ADS)

I introduce an algorithm for estimating parameters from multidimensional data based on forward modelling. It performs an iterative local search to effectively achieve a non-linear interpolation of a template grid. In contrast to many machine-learning approaches, it avoids fitting an inverse model and the problems associated with this. The algorithm makes explicit use of the sensitivities of the data to the parameters, with the goal of better treating parameters which only have a weak impact on the data. The forward modelling approach provides uncertainty (full covariance) estimates in the predicted parameters as well as a goodness-of-fit for observations, thus providing a simple means of identifying outliers. I demonstrate the algorithm, ILIUM, with the estimation of stellar astrophysical parameters (APs) from simulations of the low-resolution spectrophotometry to be obtained by Gaia. The AP accuracy is competitive with that obtained by a support vector machine. For zero extinction stars covering a wide range of metallicity, surface gravity and temperature, ILIUM can estimate Teff to an accuracy of 0.3 per cent at G = 15 and to 4 per cent for (lower signal-to-noise ratio) spectra at G = 20, the Gaia limiting magnitude (mean absolute errors are quoted). [Fe/H] and logg can be estimated to accuracies of 0.1-0.4dex for stars with G <= 18.5, depending on the magnitude and what priors we can place on the APs. If extinction varies a priori over a wide range (0-10mag) - which will be the case with Gaia because it is an all-sky survey - then logg and [Fe/H] can still be estimated to 0.3 and 0.5dex, respectively, at G = 15, but much poorer at G = 18.5. Teff and AV can be estimated quite accurately (3-4 per cent and 0.1-0.2mag, respectively, at G = 15), but there is a strong and ubiquitous degeneracy in these parameters which limits our ability to estimate either accurately at faint magnitudes. Using the forward model, we can map these degeneracies (in advance) and thus provide a complete probability distribution over solutions. Additional information from the Gaia parallaxes, other surveys or suitable priors should help reduce these degeneracies.

Bailer-Jones, C. A. L.

2010-03-01

103

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

104

Deriving hydrogeological parameters through time series analysis of groundwater head fluctuations around well fields  

NASA Astrophysics Data System (ADS)

A method is presented by which time series analysis is applied to support groundwater system conceptualization and provide calibration targets for a steady groundwater model. The method is demonstrated for heads measured in the vicinity of a drinking-water well field. The estimated steady response to pumping was used to classify the monitoring wells as semi-confined or phreatic. Based on this conceptualization, the aquifer system was represented by two layers separated by a leaky bed, which represents the resistance to vertical flow of the layers. The model could be calibrated satisfactorily using the drawdowns estimated by time series analysis. This approach was more successful than deriving the aquifer parameters directly from the analytical well function of Hantush, which was successful for a limited number of monitoring wells only and required the a priori choice of the elevation of a confining layer which was not clear from bore logs. This study shows that time series analysis can lead to qualitative and quantitative insights regarding the local hydrogeology, providing complementary information to available bore logs to design a conceptual groundwater model. Time series analysis provides a cost-effective alternative to pumping tests when measured head fluctuations influenced by pumping wells are available.

Obergfell, Christophe; Bakker, Mark; Zaadnoordijk, Willem Jan; Maas, Kees

2013-08-01

105

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

106

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

NASA Astrophysics Data System (ADS)

Mesoscale meteorological modelling is an important tool to help understand air pollution and heat island effects in urban areas. Accurate wind simulations are difficult 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 atmosphere. This paper examines an episode during the MCMA-2003 field campaign held in the Mexico City Metropolitan Area (MCMA) in April of 2003. High resolution satellite observations are used to specify the land use, vegetation fraction, albedo and surface temperature in the MM5 model. Making use of these readily available data leads to improved meteorological simulations in the MCMA, both for the wind circulation patterns and the urban heat island. Replacing values previously obtained from land-use tables with actual measurements removes the number of unknowns in the model and increases the accuracy of the energy budget. In addition to improving the understanding of local meteorology, this sets the stage for the use of advanced urban modules.

de Foy, B.; Molina, L. T.; Molina, M. J.

2005-10-01

107

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

NASA Astrophysics Data System (ADS)

Mesoscale meteorological modelling is an important tool to help understand air pollution and heat island effects in urban areas. Accurate wind simulations are difficult 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 atmosphere. This paper examines an episode during the MCMA-2003 field campaign held in the Mexico City Metropolitan Area (MCMA) in April of 2003. Because the episode has weak synoptic forcing, there is the potential for the surface heat budget to influence the local meteorology. High resolution satellite observations are used to specify the land use, vegetation fraction, albedo and surface temperature in the MM5 model. Making use of these readily available data leads to improved meteorological simulations in the MCMA, both for the wind circulation patterns and the urban heat island. Replacing values previously obtained from land-use tables with actual measurements removes the number of unknowns in the model and increases the accuracy of the energy budget. In addition to improving the understanding of local meteorology, this sets the stage for the use of advanced urban modules.

de Foy, B.; Molina, L. T.; Molina, M. J.

2006-04-01

108

Structure of dimension-six derivative interactions in pseudo Nambu-Goldstone N Higgs doublet models  

E-print Network

We derive the general structure of dimension-six derivative interactions in the N Higgs doublet models, where Higgs fields arise as pseudo Nambu-Goldstone modes of a strongly interacting sector. We show that there are several relations among the dimension-six operators, and therefore the number of independent operators decreases compared with models on which only SU(2)_L x U(1)_Y invariance is imposed. As an explicit example, we derive scattering amplitudes of longitudinal gauge bosons and Higgs bosons at high energy on models involving two Higgs doublets, and compare them with the amplitudes in the case of one Higgs doublet.

Yohei Kikuta; Yasuhiro Okada; Yasuhiro Yamamoto

2012-04-25

109

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

110

CM-SAF's climate monitoring products for the Arctic: cloud parameters and surface albedo derived from meteorological satellites  

Microsoft Academic Search

As component of EUMETSAT's activities in climate monitoring, the Satellite Application Fa-cility on Climate Monitoring (CM-SAF; www.cmsaf.eu) provides climate monitoring products derived from meteorological satellites. The CM-SAF's product suite has recently been extended to the Arctic. Several cloud parameters (cloud fraction; cloud type; cloud top height \\/ temperature \\/ pressure) as well as surface albedo are derived from the Advanced

Frank Kaspar; Rainer Hollmann; Maarit Lockhoff; Karl-G. Karlsson; Anke Kniffka; Diana Stein; Petra Fuchs

2010-01-01

111

Estimating crop net primary production using inventory data and MODIS-derived parameters  

SciTech Connect

National estimates of spatially-resolved cropland net primary production (NPP) are needed for diagnostic and prognostic modeling of carbon sources, sinks, and net carbon flux. Cropland NPP estimates that correspond with existing cropland cover maps are needed to drive biogeochemical models at the local scale and over national and continental extents. Existing satellite-based NPP products tend to underestimate NPP on croplands. A new Agricultural Inventory-based Light Use Efficiency (AgI-LUE) framework was developed to estimate individual crop biophysical parameters for use in estimating crop-specific NPP. The method is documented here and evaluated for corn and soybean crops in Iowa and Illinois in years 2006 and 2007. The method includes a crop-specific enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS), shortwave radiation data estimated using Mountain Climate Simulator (MTCLIM) algorithm and crop-specific LUE per county. The combined aforementioned variables were used to generate spatially-resolved, crop-specific NPP that correspond to the Cropland Data Layer (CDL) land cover product. The modeling framework represented well the gradient of NPP across Iowa and Illinois, and also well represented the difference in NPP between years 2006 and 2007. Average corn and soybean NPP from AgI-LUE was 980 g C m-2 yr-1 and 420 g C m-2 yr-1, respectively. This was 2.4 and 1.1 times higher, respectively, for corn and soybean compared to the MOD17A3 NPP product. Estimated gross primary productivity (GPP) derived from AgI-LUE were in close agreement with eddy flux tower estimates. The combination of new inputs and improved datasets enabled the development of spatially explicit and reliable NPP estimates for individual crops over large regional extents.

Bandaru, Varaprasad; West, Tristram O.; Ricciuto, Daniel M.; Izaurralde, Roberto C.

2013-06-03

112

Estimating crop net primary production using national inventory data and MODIS-derived parameters  

NASA Astrophysics Data System (ADS)

National estimates of spatially-resolved cropland net primary production (NPP) are needed for diagnostic and prognostic modeling of carbon sources, sinks, and net carbon flux between land and atmosphere. Cropland NPP estimates that correspond with existing cropland cover maps are needed to drive biogeochemical models at the local scale as well as national and continental scales. Existing satellite-based NPP products tend to underestimate NPP on croplands. An Agricultural Inventory-based Light Use Efficiency (AgI-LUE) framework was developed to estimate individual crop biophysical parameters for use in estimating crop-specific NPP over large multi-state regions. The method is documented here and evaluated for corn (Zea mays L.) and soybean (Glycine max L. Merr.) in Iowa and Illinois in 2006 and 2007. The method includes a crop-specific Enhanced Vegetation Index (EVI), shortwave radiation data estimated using the Mountain Climate Simulator (MTCLIM) algorithm, and crop-specific LUE per county. The combined aforementioned variables were used to generate spatially-resolved, crop-specific NPP that corresponds to the Cropland Data Layer (CDL) land cover product. Results from the modeling framework captured the spatial NPP gradient across croplands of Iowa and Illinois, and also represented the difference in NPP between years 2006 and 2007. Average corn and soybean NPP from AgI-LUE was 917 g C m-2 yr-1 and 409 g C m-2 yr-1, respectively. This was 2.4 and 1.1 times higher, respectively, for corn and soybean compared to the MOD17A3 NPP product. Site comparisons with flux tower data show AgI-LUE NPP in close agreement with tower-derived NPP, lower than inventory-based NPP, and higher than MOD17A3 NPP. The combination of new inputs and improved datasets enabled the development of spatially explicit and reliable NPP estimates for individual crops over large regional extents.

Bandaru, Varaprasad; West, Tristram O.; Ricciuto, Daniel M.; César Izaurralde, R.

2013-06-01

113

On the definition and the derivation of the characteristic parameters of coupled lines, and application to MoM analysis  

Microsoft Academic Search

This paper addresses the definition and the calculation of the characteristic parameters of coupled lines. The approach is used to derive the above characteristics from the knowledge of the network parameters of a given section of coupled lines. The latter are obtained by a full-wave method of moments (MoM), suitably de-embedded by a short-open calibration (SOC) procedure.

Marco Farina; Antonio Morini; Tullio Rozzi

2005-01-01

114

Metabolic Parameters Derived From Cardiopulmonary Stress Testing for Prediction of Prognosis in Patients With Heart Failure: The Ochsner Experience  

PubMed Central

Cardiopulmonary parameters, particularly peak oxygen consumption, have proven utility in prognostic stratification for patients with heart failure. These have been typically corrected for total body weight as opposed to lean body mass (LBM). For practical purposes, fat consumes virtually no oxygen and receives minimal perfusion. Based on this rationale and on observations from previous studies, several investigations conducted at the Ochsner Clinic Foundation have assessed the prognostic value of metabolic parameters when corrected for LBM. Three studies reviewed in this discussion consistently found greater prognostic value for LBM-corrected parameters, especially peak oxygen consumption and oxygen pulse. These findings lead to a strong recommendation for LBM correction of cardiopulmonary exercise stress test–derived parameters for more accurate prognostic stratification in patients with heart failure, especially in the obese population. Other centers have studied additional parameters such as the ventilation to carbon dioxide production slope, oxygen uptake efficiency slope, and partial pressure of end-tidal carbon dioxide during exercise and rest. In multiple studies, these ventilation-dependent parameters have shown prognostic superiority compared with the standard peak oxygen consumption even when obtained from submaximal exercise data. However, no study to our knowledge has compared these parameters with LBM-adjusted values as described herein. The prognostic validity of cardiopulmonary exercise stress test–derived parameters requires further investigation in patients treated with ?-blockers. PMID:21603413

Crespo, Joaquin; Lavie, Carl J.; Milani, Richard V.; Gilliland, Yvonne E.; Patel, Hamang M.; Ventura, Hector O.

2009-01-01

115

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

116

SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS  

SciTech Connect

The WMAP mission has produced sky maps from seven years of observations at L2. We present the angular power spectra derived from the seven-year maps and discuss the cosmological conclusions that can be inferred from WMAP data alone. With the seven-year data, the temperature (TT) spectrum measurement has a signal-to-noise ratio per multipole that exceeds unity for l < 919; and in band powers of width {Delta}l = 10, the signal-to-noise ratio exceeds unity up to l = 1060. The third acoustic peak in the TT spectrum is now well measured by WMAP. In the context of a flat {Lambda}CDM model, this improvement allows us to place tighter constraints on the matter density from WMAP data alone, {Omega}{sub m} h {sup 2} = 0.1334{sup +0.0056}{sub -0.0055}, and on the epoch of matter-radiation equality, z{sub eq} = 3196{sup +134}{sub -133}. The temperature-polarization (TE) spectrum is detected in the seven-year data with a significance of 20{sigma}, compared to 13{sigma} with the five-year data. We now detect the second dip in the TE spectrum near l {approx} 450 with high confidence. The TB and EB spectra remain consistent with zero, thus demonstrating low systematic errors and foreground residuals in the data. The low-l EE spectrum, a measure of the optical depth due to reionization, is detected at 5.5{sigma} significance when averaged over l = 2-7: l(l + 1)C {sup EE}{sub l}/(2{pi}) = 0.074{sup +0.034}{sub -0.025} {mu}K{sup 2} (68% CL). We now detect the high-l, 24 {<=} l {<=} 800, EE spectrum at over 8{sigma}. The BB spectrum, an important probe of gravitational waves from inflation, remains consistent with zero; when averaged over l = 2-7, l(l + 1)C {sup BB}{sub l}/(2{pi}) < 0.055 {mu}K{sup 2} (95% CL). The upper limit on tensor modes from polarization data alone is a factor of two lower with the seven-year data than it was using the five-year data. The data remain consistent with the simple {Lambda}CDM model: the best-fit TT spectrum has an effective {chi}{sup 2} of 1227 for 1170 degrees of freedom, with a probability to exceed of 9.6%. The allowable volume in the six-dimensional space of {Lambda}CDM parameters has been reduced by a factor of 1.5 relative to the five-year volume, while the {Lambda}CDM model that allows for tensor modes and a running scalar spectral index has a factor of three lower volume when fit to the seven-year data. We test the parameter recovery process for bias and find that the scalar spectral index, n{sub s} , is biased high, but only by 0.09{sigma}, while the remaining parameters are biased by <0.15{sigma}. The improvement in the third peak measurement leads to tighter lower limits from WMAP on the number of relativistic degrees of freedom (e.g., neutrinos) in the early universe: N{sub eff}>2.7(95%CL). Also, using WMAP data alone, the primordial helium mass fraction is found to be Y{sub He} = 0.28{sup +0.14}{sub -0.15}, and with data from higher-resolution cosmic microwave background experiments included, we now establish the existence of pre-stellar helium at >3{sigma}. These new WMAP measurements provide important tests of big bang cosmology.

Larson, D.; Bennett, C. L.; Gold, B. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2686 (United States); Dunkley, J. [Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom); Hinshaw, G.; Kogut, A.; Wollack, E. [Code 665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Komatsu, E. [Department of Astronomy, University of Texas, Austin, 2511 Speedway, RLM 15.306, Austin, TX 78712 (United States); Nolta, M. R. [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada); Halpern, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Hill, R. S.; Odegard, N.; Weiland, J. L. [ADNET Systems, Inc., 7515 Mission Dr., Suite A100 Lanham, MD 20706 (United States); Jarosik, N.; Page, L. [Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708 (United States); Limon, M. [Columbia Astrophysics Laboratory, 550 W. 120th St., Mail Code 5247, New York, NY 10027-6902 (United States); Meyer, S. S. [Departments of Astrophysics and Physics, KICP and EFI, University of Chicago, Chicago, IL 60637 (United States); Smith, K. M.; Spergel, D. N. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001 (United States); Tucker, G. S., E-mail: dlarson@pha.jhu.edu [Department of Physics, Brown University, 182 Hope St., Providence, RI 02912-1843 (United States)

2011-02-01

117

Cosmic confusion: degeneracies among cosmological parameters derived from measurements of microwave background anisotropies  

Microsoft Academic Search

In the near future, observations of the cosmic microwave background (CMB) anisotropies will provide accurate determinations of many fundamental cosmological parameters. In this paper, we analyse degeneracies among cosmological parameters to illustrate some of the limitations inherent in CMB parameter estimation. For simplicity, throughout our analysis we assume a cold dark matter universe with power-law adiabatic scalar and tensor fluctuation

G. Efstathiou; J. R. Bond

1999-01-01

118

Study on the synthesis of sulfonamide derivatives and their interaction with bovine serum albumin.  

PubMed

Three sulfonamide derivatives (SAD) were first synthesized from p-hydroxybenzoic acid and sulfonamides (sulfadimidine, sulfamethoxazole and sulfachloropyridazine sodium) and were characterized by elemental analysis, (1) H NMR and MS. The interaction between bovine serum albumin (BSA) and SAD was studied using UV/vis absorption spectroscopy, fluorescence spectroscopy, time-resolved fluorescence spectroscopy and circular dichroism spectra under imitated physiological conditions. The experimental results indicated that SAD effectively quenched the intrinsic fluorescence of BSA via a static quenching process. The thermodynamic parameters showed that hydrogen bonding and van der Waal's forces were the predominant intermolecular forces between BSA and two SADs [4-((4-(N-(4,6-dimethylpyrimidin-2-yl)sulfamoyl)phenyl)carbamoyl)phenyl acetate and 4-((4-(N-(5-methylisoxazol-3-yl)sulfamoyl)phenyl)carbamoyl)phenyl acetate], but hydrophobic forces played a major role in the binding process of BSA and 4-((4-(N-(6-chloropyridazin-3-yl)sulfamoyl)phenyl) carbamoyl)phenyl acetate. In addition, the effect of SAD on the conformation of BSA was investigated using synchronous fluorescence spectroscopy and circular dichroism spectra. Molecular modeling results showed that SAD was situated in subdomain IIA of BSA. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24923629

Zhang, Xuehong; Lin, Yijie; Liu, Lina; Lin, Cuiwu

2015-05-01

119

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

120

Mechanical Analysis and Measurement of Parameters of Wheel -Soil Interaction for a Lunar Rover  

NASA Astrophysics Data System (ADS)

Mechanical models of the wheel-soil interaction are constructed for a rigid wheel of lunar rover when rolling and steering, based on the theories of terramechanics and passive earth pressure. The mechanical affect of different parameters of the soil to the rigid wheel is analysed, such as drawbar pull, rolling torque and steering torque. Experimental results of a rigid wheel in a kind of dry soil, whose mechanical parameters are some similar to lunar soil, validate the models correct. A novel test-bed and its data acquisition system are also designed for testing the performance of the wheel-soil interaction of lunar rover, and their key technologies concerned are discussed.

Tao, J. G.; Wang, L.; Deng, Z. Q.; Gao, H. B.; Quan, Q. Q.

2006-10-01

121

Effects of the interaction between dark energy and dark matter on cosmological parameters  

SciTech Connect

We examine the effects of possible phenomenological interactions between dark energy and dark matter on cosmological parameters and their efficiency in solving the coincidence problem. We work with two simple parameterizations of the dynamical dark energy equation of state and the constant dark energy equation of state. Using observational data coming from the new 182 Gold type Ia supernova samples, the shift parameter of the Cosmic Microwave Background given by the three-year Wilkinson Microwave Anisotropy Probe observations and the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, we perform a statistical joint analysis of different forms of phenomenological interaction between dark energy and dark matter.

He, Jian-Hua; Wang, Bin, E-mail: 062019010@fudan.edu.cn, E-mail: wangb@fudan.edu.cn [Department of Physics, Fudan University, Shanghai 200433 (China)] [Department of Physics, Fudan University, Shanghai 200433 (China)

2008-06-15

122

Generalized projection operator method to derive the pulse parameters equations for the nonlinear  

E-print Network

: Nonlinear Schro¨dinger equation; Optical fibers; Lagrangian variational method; Ordinary differential projection operator method for deriving the ordinary differential equations (ODEs) which describe the pulse to derive the ordinary differential equations (ODEs) which describe the pulse dynamics of the Klein

Wai, Ping-kong Alexander

123

Emergent Learning and Interactive Media Artworks: Parameters of Interaction for Novice Groups  

ERIC Educational Resources Information Center

Emergent learning describes learning that occurs when participants interact and distribute knowledge, where learning is self-directed, and where the learning destination of the participants is largely unpredictable (Williams, Karousou, & Mackness, 2011). These notions of learning arise from the topologies of social networks and can be applied to…

Kawka, Marta; Larkin, Kevin; Danaher, P. A.

2011-01-01

124

Effect of including torsional parameters for histidine-metal interactions in classical force fields for metalloproteins.  

PubMed

Classical force-field parameters of the metal site of metalloproteins usually comprise only the partial charges of the involved atoms, as well as the bond-stretching and bending parameters of the metal-ligand interactions. Although for certain metal ligands such as histidine residues, the torsional motions at the metal site play an important role for the dynamics of the protein, no such terms have been considered to be crucial in the parametrization of the force fields, and they have therefore been omitted in the parametrization. In this work, we have optimized AMBER-compatible force-field parameters for the reduced state of the metal site of copper, zinc superoxide dismutase (SOD1) and assessed the effect of including torsional parameters for the histidine-metal interactions in molecular dynamics simulations. On the basis of the obtained results, we recommend that torsion parameters of the metal site are included when processes at the metal site are investigated or when free-energy calculations are performed. As the torsion parameters mainly affect the structure of the metal site, other kinds of structural studies can be performed without considering the torsional parameters of the metal site. PMID:25410708

Mera-Adasme, Raúl; Sadeghian, Keyarash; Sundholm, Dage; Ochsenfeld, Christian

2014-11-20

125

Snow parameters derived from microwave measurements during the BOREAS winter field campaign  

Microsoft Academic Search

Passive microwave data have been used to infer the snow-covered area and snow water equivalent (SWE) over forested areas, but the accuracy of these retrieved snow parameters cannot be easily validated for heterogeneous vegetated regions. The Boreal Ecosystem-Atmosphere Study Winter Field Campaign provided the opportunity to study the effect of boreal forests on snow parameter retrieval in detail. Microwave radiometers

A. T. C. Chang; J. L. Foster; D. K. Hall; B. E. Goodison; A. E. Walker; J. R. Metcalfe; A. Harby

1997-01-01

126

Characterization of the Flory-Huggins interaction parameter of polymer thermodynamics  

NASA Astrophysics Data System (ADS)

Flory-Huggins theory is the main basis of polymer solution and blend thermodynamics. A key piece of this theory is a parameter quantifying the enthalpic interactions between the components; however, experiments have revealed that this parameter is not composition independent, as originally assumed. This composition dependence has been attributed by some theorists to experimental error; others have tried to explain it based on several competing hypotheses. Here, we use atomistic simulations of isotopic blends based on realistic potentials to study this parameter without making any prior hypotheses. Simulations reveal a composition dependence of this parameter that compares well with experimental data, and serve to verify theoretical relationships between the various forms of this parameter.

Russell, Travis H.; Edwards, Brian J.; Khomami, Bamin

2014-12-01

127

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

128

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

129

Mechanical Analysis and Measurement of Parameters of Wheel Soil Interaction for a Lunar Rover  

Microsoft Academic Search

Mechanical models of the wheel-soil interaction are constructed for a rigid wheel of lunar rover when rolling and steering, based on the theories of terramechanics and passive earth pressure. The mechanical affect of different parameters of the soil to the rigid wheel is analysed, such as drawbar pull, rolling torque and steering torque. Experimental results of a rigid wheel in

J G Tao; L Wang; Z Q Deng; H B Gao; Q Q Quan

2006-01-01

130

Interactive fuzzy programming for multi-level linear programming problems with fuzzy parameters  

Microsoft Academic Search

This paper presents interactive fuzzy programming for multi-level linear programming problems with fuzzy parameters. In fuzzy programming for multi-level linear programming problems, recently developed by Lai et al., since the fuzzy goals are determined for both an objective function and decision variables at the upper level, undesirable solutions are produced when these fuzzy goals are inconsistent. In order to overcome

Masatoshi Sakawa; Ichiro Nishizaki; Yoshio Uemura

2000-01-01

131

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

132

DATA BASE ANALYZER AND PARAMETER ESTIMATOR (DBAPE) INTERACTIVE COMPUTER PROGRAM--USER'S MANUAL  

EPA Science Inventory

The Data Base Analyzer and Parameter Estizator (DBAPE) is an interactive computer progran that provides a link between two of EPA's development products--an environmental model and a data base. BAPE was created to encourage and support the use of the RUSTIC model, a newly develop...

133

Deriving the static interaction between electric dipoles via the quantum gauge transformation  

E-print Network

Gauge transformation leaves the electric and the magnetic fields unchanged as long as the gauge function is treated classically. In this paper we consider the gauge transformation commonly used to obtain the electric dipole interaction Hamiltonian in a system of dipoles and the electromagnetic field (Goeppert-Mayer transformation) and treat the vector potential that appear in the gauge function as an operator. While it modifies the electric field, the static interaction between the dipoles is derived.

Makoto Morinaga

2013-02-14

134

Study of interaction between human serum albumin and three phenanthridine derivatives: Fluorescence spectroscopy and computational approach.  

PubMed

Over the past decades, phenanthridine derivatives have captured the imagination of many chemists due to their wide applications. In the present work, the interaction between phenanthridine derivatives benzo [4,5]imidazo[1,2-a]thieno[2,3-c]quinoline (BTQ), benzo[4,5]imidazo[1,2-a]furo[2,3-c]quinoline (BFQ), 5,6-dimethylbenzo[4,5]imidazo[1,2-a]furo[2,3-c]quinoline (DFQ) and human serum albumin (HSA) were investigated by molecular modeling techniques and spectroscopic methods. The results of molecular modeling simulations revealed that the phenanthridine derivatives could bind on both site I in HSA. Fluorescence data revealed that the fluorescence quenching of HSA by phenanthridine derivatives were the result of the formation of phenanthridine derivatives-HSA complex, and the binding intensity between three phenanthridine derivatives and HSA was BTQ>BFQ>DFQ. Thermodynamics confirmed that the interaction were entropy driven with predominantly hydrophobic forces. The effects of some biological metal ions and toxic ions on the binding affinity between phenanthridine derivatives and HSA were further examined. PMID:25796018

Liu, Jianming; Yue, Yuanyuan; Wang, Jing; Yan, Xuyang; Liu, Ren; Sun, Yangyang; Li, Xiaoge

2015-06-15

135

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

136

Interactions of aminoalkylcarbamoyl cellulose derivatives and sodium dodecyl sulfate. 2. Foam stabilization  

Microsoft Academic Search

We have compared the interactions between polyquaternium 10 and sodium dodecyl sulfate with similar complexes of mono and diquaternary ammoniumalkylcarbamoyl cellulose derivatives by measuring the foaming efficiency and foam stability of their aqueous solutions. At approximately a 1:1 stoichiometric ratio of sodium dodecyl sulfate (SDS) to quaternary groups, an insoluble precipitate began to form. Maximum foamability and foam stabilization were

Melissa Manuszak Guerrini; Robert Y. Lochhead; William H. Daly

1999-01-01

137

Physicochemical study on interactions between T-2 and HT-2 toxin derivatives and cyclodextrins  

Technology Transfer Automated Retrieval System (TEKTRAN)

Physicochemical interactions occurring between fluorescent anthracene derivatives of T-2 and HT-2 toxins and different cyclodextrins (CDs) were investigated in aqueous solutions by means of UV-Vis absorption, fluorescence emission, and Dynamic Light Scattering. Binding constant values and physicoche...

138

BUILDING AN INTERACTIVE NEXT-GENERATION ARTIST RECOMMENDER BASED ON AUTOMATICALLY DERIVED HIGH-LEVEL CONCEPTS  

E-print Network

BUILDING AN INTERACTIVE NEXT-GENERATION ARTIST RECOMMENDER BASED ON AUTOMATICALLY DERIVED HIGH Intelligence (OFAI) Vienna, Austria ABSTRACT We present a new way of accessing large sets of musical artists based on high-level concepts. The concepts are de- rived and assigned to individual artists

Widmer, Gerhard

139

Temperature evaluation of traveling-wave ultrasonic motor considering interaction between temperature rise and motor parameters.  

PubMed

In this paper, a novel model for evaluating the temperature of traveling-wave ultrasonic motor (TWUSM) is developed. The proposed model, where the interaction between the temperature rise and motor parameters is considered, differs from the previous reported models with constant parameters. In this model, losses and temperature rises of the motor were evaluated based on the temperature-related varying parameters: the feedback voltage Vaux of the stator, dielectric permittivity ? and dielectric loss factor tan?. At each new temperature, Vaux, ? and tan? were updated. The feasibility and effectiveness of this proposed model was verified by comparing the predicted temperatures with the measured one. The effects of driving voltage, driving frequency and ambient temperature on the predicted temperature were also analyzed. The results show that the proposed model has more accurate predicted temperature than that with constant parameters. This will be very useful for the optimal design, reducing the heat loss, improvement of control and reliability life of TWUSM. PMID:25481041

Li, Shiyang; Ou, Wenchu; Yang, Ming; Guo, Chao; Lu, Cunyue; Hu, Junhui

2015-03-01

140

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

141

Comparison between the interannual variability of snow parameters derived from SSM\\/I and the Ob river discharge  

Microsoft Academic Search

This paper analyses the relationship between the interannual variations of snow depth and snowmelt date and river discharge measurements in the Ob river basin. The snow parameters are derived from passive microwave remote sensing measurements by SSM\\/I during the time period 1989–2001. We find a significant correlation between the snowmelt date and the runoff in May (correlation coefficient R=?0.92) and

M. Grippa; N. Mognard; T. Le Toan

2005-01-01

142

Spectroscopic studies on the interaction of cinnamic acid and its hydroxyl derivatives with human serum albumin  

NASA Astrophysics Data System (ADS)

Cinnamic acid and its derivatives possess various biological effects in remedy of many diseases. Interaction of cinnamic acid and its hydroxyl derivatives, p-coumaric acid and caffeic acid, with human serum albumin (HSA), and concomitant changes in its conformation were studied using fluorescence and Fourier transform infrared spectroscopic methods. Fluorescence data revealed the presence of one binding site on HSA for cinnamic acid and its hydroxyl derivatives, and their binding constants ( KA) are caffeic acid> p-coumaric acid> cinnamic acid when Cdrug/ CHSA ranging from 1 to 10. The changes of the secondary structure of HSA after interacting with the three drugs are estimated, respectively by combining the curve-fitting results of amid I and amid III bands. The ?-helix structure has a decrease of ?9, 5 and 3% after HSA interacted with caffeic acid, p-coumaric acid and cinnamic acid, respectively. It was found that the hydroxyls substituted on aromatic ring of the drugs play an important role in the changes of protein's secondary structure. Combining the result of fluorescence quenching and the changes of secondary structure of HSA after interaction with the three drugs, the drug-HSA interaction mode was discussed.

Min, Jiang; Meng-Xia, Xie; Dong, Zheng; Yuan, Liu; Xiao-Yu, Li; Xing, Chen

2004-04-01

143

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

144

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

145

Deriving parameters of a fundamental detachment model for cohesive soils from flume and jet erosion tests  

Technology Transfer Automated Retrieval System (TEKTRAN)

The erosion rate of cohesive soils is commonly quantified using the excess shear stress equation, dependent on two major soil parameters: the critical shear stress and the erodibility coefficient. A submerged jet test (JET – Jet Erosion Test) is one method that has been developed for measuring thes...

146

Gravity wave parameters derived from traveling ionospheric disturbances observations in the auroral zone  

Microsoft Academic Search

Large-scale wavelike fluctuations of ion velocity, as measured by the European incoherent scatter radar along the geomagnetic field line, have been attributed to gravity wave effects. The height-dependent parameters of the causative gravity waves are calculated, taking into account the neutral horizontal wind and the electric field. The results are compared with the solutions of a dissipative dispersion relation. Much

L. Natorf; K. Schlegel; A. W. Wernik

1992-01-01

147

Impulse source versus dodecahedral loudspeaker for measuring parameters derived from the impulse response in room acoustics.  

PubMed

This study investigates the performance of dodecahedral and impulse sources when measuring acoustic parameters in enclosures according to ISO 3382-1 [Acoustics-Measurement of room acoustic parameters. Part 1: Performance spaces (International Organization for Standardization, Geneva, Switzerland, 2009)]. In general, methods using speakers as a sound source are limited by their frequency response and directivity. On the other hand, getting impulse responses from impulse sources typically involves a lack of repeatability, and it is usually necessary to average several measurements for each position. Through experiments in different auditoriums that recreate typical situations in which the measurement standard is applied, it is found that using impulse sources leads to greater variation in the results, especially at low frequencies. However, this prevents subsequent dispersions due to variables that this technique does not require, such as the orientation of the emitting source. These dispersions may be relevant at high frequencies exceeding the established tolerance criteria for certain parameters. Finally, a new descriptor for dodecahedral sources reflecting the influence their lack of omnidirectionality produces on measuring acoustic parameters is proposed. PMID:23862805

San Martín, Ricardo; Arana, Miguel; Machín, Jorge; Arregui, Abel

2013-07-01

148

Implicit Solvation Parameters Derived from Explicit Water Forces in Large-Scale Molecular Dynamics Simulations.  

PubMed

Implicit solvation is a mean force approach to model solvent forces acting on a solute molecule. It is frequently used in molecular simulations to reduce the computational cost of solvent treatment. In the first instance, the free energy of solvation and the associated solvent-solute forces can be approximated by a function of the solvent-accessible surface area (SASA) of the solute and differentiated by an atom-specific solvation parameter ?(i) (SASA). A procedure for the determination of values for the ?(i) (SASA) parameters through matching of explicit and implicit solvation forces is proposed. Using the results of Molecular Dynamics simulations of 188 topologically diverse protein structures in water and in implicit solvent, values for the ?(i) (SASA) parameters for atom types i of the standard amino acids in the GROMOS force field have been determined. A simplified representation based on groups of atom types ?(g) (SASA) was obtained via partitioning of the atom-type ?(i) (SASA) distributions by dynamic programming. Three groups of atom types with well separated parameter ranges were obtained, and their performance in implicit versus explicit simulations was assessed. The solvent forces are available at http://mathbio.nimr.mrc.ac.uk/wiki/Solvent_Forces. PMID:23180979

Kleinjung, Jens; Scott, Walter R P; Allison, Jane R; van Gunsteren, Wilfred F; Fraternali, Franca

2012-07-10

149

Nonparametric Estimation of Derivative Functions with Data-Driven Optimally Selected Smoothing Parameters  

E-print Network

are not necessarily the proper surrogates when inter- est instead hinges on the derivative of the unknown function. Economic applications which require gradient estimation include estimates of heterogenous individual atti- tudes toward risk (Chiapporis, Gandhi... in single-index panel data models with heterogeneous link functions. Econometric Reviews, 32(8):928–955, 2013. P. A. Chiapporis, A. Gandhi, B. Salanie´, and F. Salanie´. Identifying preferences under risk from discrete choices. American Economic Review, 99...

Yao, Shuang

2014-07-30

150

Identifying and reducing model structure uncertainty based on analysis of parameter interaction  

NASA Astrophysics Data System (ADS)

Multi-objective optimization algorithms are widely used for the calibration of conceptual hydrological models. Such algorithms yield a set of Pareto-optimal solutions, reflecting the model structure uncertainty. In this study, a multi-objective optimization strategy is suggested, which aims at reducing the model structure uncertainty by considering parameter interaction within Pareto-optimal solutions. The approach has been used to develop a nested setup of a rainfall-runoff model, which is integrated in a probabilistic meso-/macroscale flood forecasting system. The optimization strategy aided in determining the best combination of a lumped (computationally efficient in operational real time forecasting) and a semi-distributed parameterization of the hydrological model. First results are shown for two subbasins of the Mulde catchment in Germany. The different phenomena of parameter interaction were analysed in this case study to reduce the model structure uncertainties.

Wang, Y.; Dietrich, J.; Voss, F.; Pahlow, M.

2007-06-01

151

Comparison of CME three-dimensional parameters derived from single and multi-spacecraft  

NASA Astrophysics Data System (ADS)

Several geometrical models (e.g., cone and flux rope models) have been suggested to infer three-dimensional parameters of CMEs using multi-view observations (STEREO/SECCHI) and single-view observations (SOHO/LASCO). To prepare for when only single view observations are available, we have made a test whether the cone model parameters from single-view observations are consistent with those from multi-view ones. For this test, we select 35 CMEs which are identified as CMEs, whose angular widths are larger than 180 degrees, by one spacecraft and as limb CMEs by the other ones. For this we use SOHO/LASCO and STEREO/SECCHI data during the period from 2010 December to 2011 July when two spacecraft were separated by 90±10 degrees. In this study, we compare the 3-D parameters of these CMEs from three different methods: (1) a triangulation method using STEREO/SECCHI and SOHO/LASCO data, (2) a Graduated Cylindrical Shell (GCS) flux rope model using STEREO/SECCHI data, and (3) an ice cream cone model using SOHO/LASCO data. The parameters used for comparison are radial velocities, angular widths and source location (angle ? between the propagation direction and the plan of the sky). We find that the radial velocities and the ?-values from three methods are well correlated with one another (CC > 0.8). However, angular widths from the three methods are somewhat different with the correlation coefficients of CC > 0.4. We also find that the correlation coefficients between the locations from the three methods and the active region locations are larger than 0.9, implying that most of the CMEs are radially ejected.

LEE, Harim; Moon, Yong-Jae; Na, Hyeonock; Jang, Soojeong

2014-06-01

152

S-Wave Shape-Dependent Scattering Parameters of the Proton-Proton Interaction  

Microsoft Academic Search

The shape-dependent parameters P and Q of the effective-range expansion for the S-wave p-p interaction have been obtained from experimental data between 0 and 10 MeV, including recent results at 6.141, 8.097, and 9.918 MeV. The preferred best values are P=0.072+\\/-0.005 and Q=0.034+\\/-0.004.

R. J. Slobodrian

1968-01-01

153

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

E-print Network

Measurements of Natural Molybdenum G. Leinweber,* D. P. Barry, J. A. Burke, and N. J. Drindak Bechtel Marine was used to explore neutron interactions with molybdenum in the energy region from 10 eV to 2 keV. Neutron of elemental molybdenum metal samples ranging from 0.051 mm (0.002 in.) to 6.35 mm (0.250 in.) were measured

Danon, Yaron

154

Novel interactions of fluorinated nucleotide derivatives targeting orotidine-5?-monophosphate decarboxylase  

PubMed Central

Fluorinated nucleosides and nucleotides are of considerable interest to medicinal chemists due to their antiviral, anticancer, and other biological activities. However, their direct interactions at target binding sites are not well understood. A new class of 2?-deoxy-2?-fluoro-C6-substituted uridine and UMP derivatives were synthesized and evaluated as inhibitors of orotidine-5?-monophosphate decarboxylase (ODCase). These compounds were synthesized from the key intermediate, fully-protected 2?-deoxy-2?-fluorouridine. Among the synthesized compounds, 2?-deoxy-2?-fluoro-6-iodo-UMP covalently inhibited human ODCase with a second-order rate constant of 0.62 ± 0.02 M?1sec?1. Interestingly, the 6-cyano-2?-fluoro derivative covalently interacted with ODCase defying the conventional thinking, where its ribosyl derivative undergoes transformation into BMP by ODCase. This confirms that the 2?-fluoro moiety influences the chemistry at the C6 position of the nucleotides, thus interactions in the active site of ODCase. Molecular interactions of the 2?-fluorinated nucleotides are compared to those with the 3?-fluorinated nucleotides bound to the corresponding target enzyme, and the carbohydrate moieties were shown to bind in different conformations. PMID:21417464

Lewis, Melissa; Avina, Maria Elena Meza; Wei, Lianhu; Crandall, Ian E.; Bello, Angelica Mara; Poduch, Ewa; Liu, Yan; Paige, Christopher J.; Kain, Kevin C.; Pai, Emil F.; Kotra, Lakshmi P.

2011-01-01

155

How useful are Green-Ampt parameters derived from small rainfall simulation plots for modelling runoff at different plot lengths?  

NASA Astrophysics Data System (ADS)

Rainfall simulation on small field plots is an invaluable method to derive effective field parameters for infiltration models such as Green-Ampt. Plot scales of ca. 1m² integrate much of the micro-scale variability and processes, which ring-infiltrometers or soil core measurements cannot capture. However, these parameters have to be used with caution on larger scales, because processes such as run-on infiltration can be considerable. The Green-Ampt parameters suction across the wetting front (psi) and effective hydraulic conductivity (Ke) were estimated from rainfall simulations on two ridged fields in Togo, West Africa. Additionally, rainfall events were recorded, and on plots of 1m width and lengths of 1, 4 and 16m, total runoff volume and sediment concentration were measured. The storm runoff hydrographs of the plots were modelled with Chu's Green-Ampt variable rainfall intensity infiltration model, using the field-average parameters derived from the simulations. Potential effects of runoff lag time were assumed negligible. Calculated total runoff volumes were compared to measured runoff volumes. For the 1m plots, runoff was underestimated, as patches of seal in the furrows produced runoff already at rainfall intensities much lower than the average infiltration capacity. For the longer plots, no run-on infiltration or other scale dependent processes were assumed, so the relative error due to scale effects was proportional to the average difference or runoff depth. In contrast to the 1m plots, runoff was overestimated by a factor of 1.2 and 2 for the 4m and 16m plots, respectively. It appears that the application of the Green-Ampt effective hydraulic conductivity derived from rainfall simulations faces two main problems, which are their dependence on one single rainfall intensity and scale-effects by run-on infiltration. Errors necessarily propagate into the scale dependency of erosion and sediment transport, as these processes are directly dependent on runoff characteristics such as stream power and shear stress.

Langhans, Christoph; Engels, Lien; Tegenbos, Lize; Govers, Gerard; Diels, Jan

2010-05-01

156

Fluorescence Interaction and Determination of Calf Thymus DNA with Two Ethidium Derivatives  

Microsoft Academic Search

In this paper, we reported the syntheses and investigation of the modes of binding to DNA of the two new ethidium derivatives\\u000a containing benzoyl and phenylacetyl groups of both amines at 3-and 8- positions. The interactions between calf thymus DNA\\u000a (ct-DNA) and the two derivatives, 3,8-dibenzoylamino-5-ethyl-6-phenylphenantridinium cloride (E2) and 3,8-diphenylacetylamino-5-ethyl-6-phenylphenantridinium chloride (E3), were investigated by fluorescence quenching spectra and UV-vis

Nuriye Akbay; Zeynel Sefero?lu; Elmas Gök

2009-01-01

157

MolStruc: a force field calculation program allowing interactive modifications of the force field parameters.  

PubMed

To analyze the influence of parameters and functions on the energy and geometry obtained through different force field calculations, we have developed program MolStruc. This software allows the user to choose between two sets of functions and parameters, MM2 and AMBER. The MM2 option of the program was developed to compute the coulombic energy in a dipole or monopole approximation. To establish comparisons between the energy values, the coulombic contribution is computed in the same way in the Amber and MM2 options of the program. The force field parameters can be handled interactively (through addition or modification). The program was used to study molecules of a representative sample displaying most of the problems encountered in molecular mechanics (MM). PMID:2282362

Siri, D; Pèpe, G; Bernassau, J M

1990-12-01

158

Interactions between specific parameters of MDMA use and cognitive and psychopathological measures.  

PubMed

The aim of the present study was to investigate the relevance of different parameters of 3,4-methylenedioxymethamphetamine (MDMA) use, including age of first use, cumulative lifetime dose and highest daily dose for predicting cognitive performance and self-reported psychopathology. Moreover, interactions between those parameters were examined. Ninety-six new MDMA users were interviewed to assess their drug use, and they completed a battery of cognitive tests concerning attention and information processing speed, episodic memory and executive functioning and self-reported psychopathology. Subjects participated again after 1year to provide follow-up data. Significant associations between age of first use and cumulative lifetime dose have been found for attention and information processing speed. Furthermore, the results showed a significant effect of age of first use on the recognition performance of the episodic memory. The findings of the current study provide a first estimation of the interactions between different MDMA use parameters. Future research should focus upon additional parameters of drug use and concentrate on consequent follow-up effects. PMID:25510880

Wagner, Daniel; Adolph, Sophia; Koester, Philip; Becker, Benjamin; Gouzoulis-Mayfrank, Euphrosyne; Daumann, Joerg

2015-04-01

159

Thermal analysis to derive energetic quality parameters of soil organic matter?  

NASA Astrophysics Data System (ADS)

Many studies have dealt with thermal analysis for characterisation of soil and soil organic matter. It is a versatile tool assessing various physicochemical properties of the sample during heating and/or cooling. Especially the combination of different detection methods is highly promising. In this contribution, we will discuss the combination of thermogravimetry (TGA) with differential scanning calorimetry (DSC) in one single thermal analysis device. TGA alone helps distinguishment of soil and soil organic matter fractions with respect to their resistance towards combustion and allows a quantitative assignment of thermolabile and recalcitrant OM fractions. Combination with DSC in the same device, allows determination of energy transformation during the combustion process. Therefore, it becomes possible to determine not only the calorific value of the organic matter, but also of its fractions. We will show the potential of using the calorific values of OM fractions as quality parameter - exemplified for the analysis of soils polluted with organic matter from the olive oil production. The pollution history of these samples is largely unknown. As expected, TGA indicated a relative enrichment of the labile carbon fraction in contaminated samples with respect to the controls. The calorific values of the thermolabile and the recalcitrant fractions differ from each other, and those of the recalcitrant fractions of the polluted samples were higher than of those of the unpolluted controls. Further analyses showed correlation of the calorific value of this fraction with soil water repellency and the carbon isotopic ratio. The synthesis of our current data suggests that the content of thermolabile fraction, the isotopic ratio and calorific value of the recalcitrant fraction are useful indicators for characterizing the degree of decomposition of OMW organic matter. In this contribution, we will further discuss the potential of using the energetic parameters a quality parameter for soil organic matter.

Peikert, Benjamin; Schaumann, Gabriele Ellen

2014-05-01

160

Snow Parameters Derived from Microwave Measurements During the BOREAS Winter Field Campaign  

NASA Technical Reports Server (NTRS)

Passive microwave data have been used to infer the snow-covered area and snow water equivalent (SWE) over forested areas, but the accuracy of these retrieved snow parameters cannot be easily validated for heterogeneous vegetated regions. The Boreal Ecosystem-Atmosphere Study Winter Field Campaign provided the opportunity to study the effect of boreal forests on snow parameter retrieval in detail. Microwave radiometers (18, 37, and 92 GHz) were flown on board the Canadian National Aeronautical Establishment's Twin Otter. Flight lines covered both the southern study area near Prince Albert and the northern study area near Thompson, Canada. During the 1994 winter campaign, extensive ground-based snow cover information, including depth, density, and grain size, was collected along most of the flight lines, jointly by U.S. and Canadian investigators. Satellite data collected by the special sensor microwave imager are also used for comparison. Preliminary results reconfirmed the relationship between microwave brightness temperature and SWE. However, the effect of forest cover observed by the aircraft sensors is different from that of the satellite observations. This is probably due to the difference in footprint averaging. There were also several flight lines flown over Candle Lake and Waskesiu Lake to assess lake ice signatures. Preliminary results show the thickness of the lake ice may be inferred from the airborne microwave observations. The microwave signature relationship between lake ice and snow matches the results from radiative transfer calculations.

Chang, A. T. C.; Foster, J. L.; Hall, D. K.; Goodison, B. E.; Walker, A. E.; Metcalfe, J. R.; Harby, A.

1997-01-01

161

Derivation of the cosmological density parameter Omega0 from large-scale flows.  

PubMed Central

Methods for determining the cosmological density parameter 0 from large-scale flows are reviewed. Very consistent results using infrared astronomical satellite (IRAS) data have been obtained by different groups with completely independent methods. The two main methods involve either using maps of the galaxy distribution to predict the peculiar velocity of the Local Group or directly comparing the density field inferred from the IRAS galaxy distribution with the peculiar velocities inferred from optical distance methods. All methods based on IRAS data are consistent with Omega0 = 0.7 +/- 0.1, or if Omega0 = 1, with a bias parameter b = 1.2 +/- 0.1. Various problems associated with the method are discussed, including the issue of which waveband is optimum for such studies, bias, the universality of the luminosity function, and the convergence of the dipole. The lower values of 0 obtained in optical studies may indicate a higher degree of bias toward regions of high total matter-density for elliptical galaxies. A new study using the whole IRAS point source catalog to 0.6 jansky is described, which gives results consistent with other IRAS studies. PMID:11607394

Rowan-Robinson, M

1993-01-01

162

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

163

Current noise parameters derived from voltage noise and impedance in embryonic heart cell aggregates.  

PubMed Central

We have recorded membrane impedance and voltage noise in the pacemaker range of potentials (-70 to -59 mV) from spheroidal aggregates of 7-d embryonic chick ventricle cells made quiescent by exposure to tetrodotoxin in medium containing 4.5 mM K+. The input capacitance is proportional to aggregate volume and therefore to total membrane area. The specific membrane capacitance is 1.24 microF/cm2. The input resistance at constant potential is inversely proportional to aggregate volume and therefore to total membrane area. The specific membrane resistance in 18 k omega . cm2 at -70 mV and increases to 81 k omega . cm2 at -59 mV. The RC time constant is 22 ms at -70 mV and increases to 146 ms at -59 mV. The aggregate transmembrane small-signal impedance can be represented by a parallel RC circuit itself in parallel with an inductive branch consisting of a resistor (rL) and an inductor (L) in series. The time constant of the inductive branch (L/rL) is 340 ms, and is only weakly dependent on potential. Correlation functions of aggregate voltage noise and the impedance data were modeled by a population of channels with simple open-close kinetics. The time constant of a channel (tau s) derived from the noise analysis is 300 ms. The low frequency limit of the pacemaker current noise (SI[0]), derived from the voltage noise and impedance, increases from 10(-20) A2/Hz . cm2 at -67 mV to 10(-19) A2/Hz . cm2 at -61 mV. PMID:262547

Clay, J R; DeFelice, L J; DeHaan, R L

1979-01-01

164

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

165

Gravity wave parameters derived from traveling ionospheric disturbances observations in the auroral zone  

SciTech Connect

Large-scale wavelike fluctuations of ion velocity, as measured by the European incoherent scatter radar along the geomagnetic field line, have been attributed to gravity wave effects. The height-dependent parameters of the causative gravity waves are calculated, taking into account the neutral horizontal wind and the electric field. The results are compared with the solutions of a dissipative dispersion relation. Much better agreement is achieved for the imaginary part of the vertical wave vector than for its real part. The calculated wave damping is greater than that given by theory. The possible reasons for this are discussed. It is suggested that E x B drift of the ions and vertical neutral winds, which are characteristic features of the auroral zone ionosphere, may contribute to the observed discrepancies. 40 refs.

Natorf, L.; Schlegel, K.; Wernik, A.W. (Max-Planck-Inst. fuer Aeronomie, Katlenburg-Lindau (Germany) Space Research Centre, Warsaw (Poland))

1992-12-01

166

Hoiamide D, a marine cyanobacteria-derived inhibitor of p53/MDM2 interaction  

PubMed Central

Bioassay-guided fractionation of two cyanobacterial extracts from Papua New Guinea has yielded hoiamide D in both its carboxylic acid and conjugate base forms. Hoiamide D is a polyketide synthase (PKS)/non-ribosomal peptide synthetase (NRPS)-derived natural product that features two consecutive thiazolines and a thiazole, as well as a modified isoleucine residue. Hoiamide D displayed inhibitory activity against p53/MDM2 interaction (EC50= 4.5 ?M), an attractive target for anticancer drug development. PMID:22104152

Malloy, Karla L.; Choi, Hyukjae; Fiorilla, Catherine; Valeriote, Fred A.; Matainaho, Teatulohi; Gerwick, William H.

2011-01-01

167

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

168

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

169

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

170

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

López-Carretero, Antonio; Díaz-Castelazo, Cecilia; Boege, Karina; Rico-Gray, Víctor

2014-01-01

171

Experimental determination of the third derivative of G. I. Enthalpic interaction  

NASA Astrophysics Data System (ADS)

The solute (i)—solute interaction in terms of enthalpy, Hi-iE=N(?2HE/?ni2)=(1-xi)(?2HE/?ni?xi), the third derivative of G, was experimentally determined using a Thermal Activity Monitor isothermal titration calorimeter for aqueous solutions of 2-butoxyethanol (BE) and 1-propanol (1P). This was done using both calorimetric reference and sample vessels actively. We simultaneously titrate small and exactly equal amounts of solute i (=BE or 1P) into both cells which contain the binary mixtures at an average mole fraction, xi, which differs by a small amount ?xi. The appropriate amount of titrant ?ni was chosen so that the quotient (?HE/?ni) can be approximated as (?HE/?ni), and so that the scatter of the results is reasonable. ?HE is the thermal response from an individual cell on titration, and we measure directly the difference in the thermal response between the two cells, ?(?HE). The resulting quotient, ?(?HE)/?ni/?xi, can be approximated as (?2HE/?ni?xi) and hence provides a direct experimental avenue for the enthalpy interaction function. We varied the value of ?xi to seek its appropriate size. Since HE contains the first derivative of G with respect to T, the result is the third derivative quantity. Thus we present here a third derivative quantity directly determined experimentally for the first time.

Westh, Peter; Inaba, Akira; Koga, Yoshikata

2008-12-01

172

Optical performance monitoring of QPSK data channels by use of neural networks trained with parameters derived from asynchronous constellation diagrams.  

PubMed

We demonstrate a technique for performance monitoring of quadrature phase-shift keying data channels by simultaneously identifying optical signal-to-noise ratio (OSNR), chromatic dispersion (CD), and polarization-mode dispersion (PMD) using neural networks trained with parameters derived from asynchronous constellation diagrams. A correlation coefficient of 0.987 is reported for a set of testing data from a 40 Gbps return-to-zero, quadrature phase-shift keying (RZ-QPSK) system. The root-mean-square (RMS) errors are 0.77 dB for OSNR, 18.71 ps/nm for CD, and 1.17 ps for DGD. PMID:20389504

Jargon, Jeffrey A; Wu, Xiaoxia; Choi, Hyeon Yeong; Chung, Yun C; Willner, Alan E

2010-03-01

173

An updated natural history model of cervical cancer: derivation of model parameters.  

PubMed

Mathematical models of cervical cancer have been widely used to evaluate the comparative effectiveness and cost-effectiveness of preventive strategies. Major advances in the understanding of cervical carcinogenesis motivate the creation of a new disease paradigm in such models. To keep pace with the most recent evidence, we updated a previously developed microsimulation model of human papillomavirus (HPV) infection and cervical cancer to reflect 1) a shift towards health states based on HPV rather than poorly reproducible histological diagnoses and 2) HPV clearance and progression to precancer as a function of infection duration and genotype, as derived from the control arm of the Costa Rica Vaccine Trial (2004-2010). The model was calibrated leveraging empirical data from the New Mexico Surveillance, Epidemiology, and End Results Registry (1980-1999) and a state-of-the-art cervical cancer screening registry in New Mexico (2007-2009). The calibrated model had good correspondence with data on genotype- and age-specific HPV prevalence, genotype frequency in precancer and cancer, and age-specific cancer incidence. We present this model in response to a call for new natural history models of cervical cancer intended for decision analysis and economic evaluation at a time when global cervical cancer prevention policy continues to evolve and evidence of the long-term health effects of cervical interventions remains critical. PMID:25081182

Campos, Nicole G; Burger, Emily A; Sy, Stephen; Sharma, Monisha; Schiffman, Mark; Rodriguez, Ana Cecilia; Hildesheim, Allan; Herrero, Rolando; Kim, Jane J

2014-09-01

174

Enhancement of parameter estimation by Kerr interaction Marco G. Genoni,1,2,* Carmen Invernizzi,2,1,  

E-print Network

, then Gaussian squeezing represents the optimal resource for parameter estimation. On the other hand, in the more is the key resource to achieve pre- cise estimation of unitary 14,15 and nonunitary parameters 16 . In turnEnhancement of parameter estimation by Kerr interaction Marco G. Genoni,1,2,* Carmen Invernizzi,2

Paris, Matteo G. A.

175

Kinetic parameters for thermal decomposition of supramolecular polymers derived from diclofenac-meglumine supramolecular adducts.  

PubMed

Meglumine is an aminocarbohydrate able to form supramolecular adducts with organic acids. The recognition is based on hydrogen bonds and the structures resulting from the complexation have high solubility in water. This property has been exploited by the pharmaceutical industry in the improvement of existing drugs, and the successful example of this approach involves the poorly soluble non-steroidal anti-inflammatory drugs (NSAIDs). Investigation of the thermal behavior of adduct obtained from meglumine and the NSAID diclofenac revealed that a polymer-like material is formed from the self-assembly of diclofenac-meglumine adducts in the melt. This polymer showed a high molecular weight around 2.0×10(5)kDa. The kinetic parameters for the thermal decomposition step of the polymer were determined by the Capela-Ribeiro non-linear isoconversional method. From data for the TG curves in nitrogen atmosphere and heating rates of 5, 10, 15 and 20°Cmin(-1), the E(?) and B(?) terms could be determined, and consequently the pre-exponential factor, A(?), as well as the kinetic model, g(?). PMID:22561058

Cassimiro, Douglas L; Ferreira, Leonardo M B; Capela, Jorge M V; Crespi, Marisa S; Ribeiro, Clóvis A

2013-01-25

176

Deriving Definitive Parameters for the Long Period Cepheid S Vulpeculae (Abstract)  

NASA Astrophysics Data System (ADS)

(Abstract only) The long-period variable S Vul is now recognized to be a classical Cepheid, following a period a century ago when its status was less well established. Its pulsation period of 68.5 days makes S Vul the longest period Cepheid recognized in the Galaxy. Possible membership in an OB association was considered briefly thirty years ago, until it was discovered to be surrounded by a sparse cluster of faint stars designated as Turner 1. Membership of S Vul in the cluster was considered unlikely in the original photometric study of Turner 1 because of contradictory implications regarding the reddening and distance of S Vul with that of cluster stars, but a recent revisiting of the data supplemented by APASS observations indicates that the cluster and Cepheid are indeed related. The implications for the implied parameters of S Vul, its reddening, distance, age, and evolutionary mass, are discussed in light of our refined knowledge of the cluster in which the Cepheid resides.

Turner, D. G.

2013-12-01

177

The same number of optimized parameters scheme for determining intermolecular interaction energies  

NASA Astrophysics Data System (ADS)

We propose the Same Number Of Optimized Parameters (SNOOP) scheme as an alternative to the counterpoise method for treating basis set superposition errors in calculations of intermolecular interaction energies. The key point of the SNOOP scheme is to enforce that the number of optimized wave function parameters for the noninteracting system is the same as for the interacting system. This ensures a delicate balance between the quality of the monomer and dimer finite basis set calculations. We compare the SNOOP scheme to the uncorrected and counterpoise schemes theoretically as well as numerically. Numerical results for second-order Møller-Plesset perturbation theory (MP2) and coupled-cluster with single, double, and approximate triple excitations (CCSD(T)) show that the SNOOP scheme in general outperforms the uncorrected and counterpoise approaches. Furthermore, we show that SNOOP interaction energies calculated using a given basis set are of similar quality as those determined by basis set extrapolation of counterpoise-corrected results obtained at a similar computational cost.

Kristensen, Kasper; Ettenhuber, Patrick; Eriksen, Janus Juul; Jensen, Frank; Jørgensen, Poul

2015-03-01

178

The same number of optimized parameters scheme for determining intermolecular interaction energies.  

PubMed

We propose the Same Number Of Optimized Parameters (SNOOP) scheme as an alternative to the counterpoise method for treating basis set superposition errors in calculations of intermolecular interaction energies. The key point of the SNOOP scheme is to enforce that the number of optimized wave function parameters for the noninteracting system is the same as for the interacting system. This ensures a delicate balance between the quality of the monomer and dimer finite basis set calculations. We compare the SNOOP scheme to the uncorrected and counterpoise schemes theoretically as well as numerically. Numerical results for second-order Møller-Plesset perturbation theory (MP2) and coupled-cluster with single, double, and approximate triple excitations (CCSD(T)) show that the SNOOP scheme in general outperforms the uncorrected and counterpoise approaches. Furthermore, we show that SNOOP interaction energies calculated using a given basis set are of similar quality as those determined by basis set extrapolation of counterpoise-corrected results obtained at a similar computational cost. PMID:25796240

Kristensen, Kasper; Ettenhuber, Patrick; Eriksen, Janus Juul; Jensen, Frank; Jørgensen, Poul

2015-03-21

179

DERIVING THE PHYSICAL PARAMETERS OF A SOLAR EJECTION WITH AN ISOTROPIC MAGNETOHYDRODYNAMIC EVOLUTIONARY MODEL  

SciTech Connect

The time-space evolution of a {approx}50 Degree-Sign wide coronal mass ejection (CME) on 2007 May 21 is followed remotely with the Solar Terrestrial Relations Observatory heliospheric imager HI-1, and measured in situ near Venus by the MESSENGER and Venus-Express spacecraft. The paper compares the observations of the CME structure with a simple, analytical magnetohydrodynamic force-free solution. It corresponds to a self-similar evolution, which gives a consistent picture of the main spatial-temporal features for both remote and in situ observations. Our main findings are (1) the self-similar evolution allows us to map the CME bright front into about 1/3 of the whole interplanetary counterpart of the coronal mass ejection (ICME, i.e., corresponding to the in situ observed passage of the plasma and magnetic field structure), in good quantitative agreement with the imaging measurements, (2) the cavity following the CME front maps into the rest of the ICME structure, 80% or more of which is consistent with a force free, cylindrically shaped flux rope, and (3) time and space conditions constrain the translational speed of the FR center to 301 km s{sup -1}, and the expansion speed of the FR core to 26 km s{sup -1}. A careful determination of the ICME cross-section and volume allows us to calculate the mass of the CME bright region (4.3 {+-} 1.1 10{sup 14} g) from the in situ measurements of the proton number density, which we assume to be uniform inside the bright region, of excellent agreement with the value estimated from the SECCHI HI-1 observations for the same structure. We provide model estimates for several global parameters including FR helicity ({approx}2 Multiplication-Sign 10{sup 26} Weber{sup 2}).

Berdichevsky, Daniel B. [Department of Electrical and Computer Engineering, University of the District of Columbia, Washington, DC 20008 (United States); Stenborg, Guillermo [College of Sciences, George Mason University, Fairfax, VA 22030 (United States); Vourlidas, Angelos [Space Sciences Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2011-11-01

180

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

E-print Network

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.

Yu-Feng Li; Ye-Ling Zhou

2015-03-20

181

Spatial Prediction of Soil Classes by Using Soil Weathering Parameters Derived from vis-NIR Spectroscopy  

NASA Astrophysics Data System (ADS)

There is consensus in the scientific community about the great need of spatial soil information. Conventional mapping methods are time consuming and involve high costs. Digital soil mapping has emerged as an area in which the soil mapping is optimized by the application of mathematical and statistical approaches, as well as the application of expert knowledge in pedology. In this sense, the objective of the study was to develop a methodology for the spatial prediction of soil classes by using soil spectroscopy methodologies related with fieldwork, spectral data from satellite image and terrain attributes in simultaneous. The studied area is located in São Paulo State, and comprised an area of 473 ha, which was covered by a regular grid (100 x 100 m). In each grid node was collected soil samples at two depths (layers A and B). There were extracted 206 samples from transect sections and submitted to soil analysis (clay, Al2O3, Fe2O3, SiO2 TiO2, and weathering index). The first analog soil class map (ASC-N) contains only soil information regarding from orders to subgroups of the USDA Soil Taxonomy System. The second (ASC-H) map contains some additional information related to some soil attributes like color, ferric levels and base sum. For the elaboration of the digital soil maps the data was divided into three groups: i) Predicted soil attributes of the layer B (related to the soil weathering) which were obtained by using a local soil spectral library; ii) Spectral bands data extracted from a Landsat image; and iii) Terrain parameters. This information was summarized by a principal component analysis (PCA) in each group. Digital soil maps were generated by supervised classification using a maximum likelihood method. The trainee information for this classification was extracted from five toposequences based on the analog soil class maps. The spectral models of weathering soil attributes shown a high predictive performance with low error (R2 0.71 to 0.90). The spatial prediction of these attributes also showed a high performance (validations with R2> 0.78). These models allowed to increase spatial resolution of soil weathering information. On the other hand, the comparison between the analog and digital soil maps showed a global accuracy of 69% for the ASC-N map and 62% in the ASC-H map, with kappa indices of 0.52 and 0.45 respectively.

Ramirez-Lopez, Leonardo; Alexandre Dematte, Jose

2010-05-01

182

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

183

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

NASA Astrophysics Data System (ADS)

The dependence on volume fraction ? of the Flory-Huggins interaction parameter ? wp (?) describing the free energy of mixing of polymers in water is obtained by exploiting the connection of ? wp (?) 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 (polyethylene oxide) oligomers. For CH3(CH2-O-CH2)mCH3 (m = 11), ? wp (?) depends strongly on ?, consistent with experiment. These results identify coexisting water-rich and water-poor solutions at T = 300 K and p = 1 atm. 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.

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

2014-12-01

184

Microscopic calculation of interacting boson model parameters by potential-energy surface mapping  

SciTech Connect

A coherent state technique is used to generate an interacting boson model (IBM) Hamiltonian energy surface which is adjusted to match a mean-field energy surface. This technique allows the calculation of IBM Hamiltonian parameters, prediction of properties of low-lying collective states, as well as the generation of probability distributions of various shapes in the ground state of transitional nuclei, the last two of which are of astrophysical interest. The results for krypton, molybdenum, palladium, cadmium, gadolinium, dysprosium, and erbium nuclei are compared with experiment.

Bentley, I. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Frauendorf, S. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); ISP, Forschungszentrum Dresden-Rossendorf, Dresden (Germany)

2011-06-15

185

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

186

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

PubMed

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 (CEM 43) 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

2013-09-01

187

Chemical and molecular aspects on interactions of galanthamine and its derivatives with cholinesterases.  

PubMed

Dual action of galanthamine as potent cholinesterase inhibitor and nicotinic modulator has attracted a great attention to be used in the treatment of AD. Consequently, galanthamine, a natural alkaloid isolated from a Galanthus species (snowdrop, Amaryllidaceae), has become an attractive model compound for synthesis of its novel derivatives to discover new drug candidates. Numerous studies have been done to elucidate interactions between galanthamine and its different derivatives and the enzymes; acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) using in vitro and in silico experimental models. The in vitro studies revealed that galanthamine inhibits AChE in strong, competitive, long-acting, and reversible manner as well as BChE, although its selectivity towards AChE is much higher than BChE. The in silico studies carried out by employing molecular docking experiments as well as molecular dynamics simulations pointed out to existence of strong interactions of galanthamine with the active gorge of AChE, mostly of Torpedo californica (the Pasific electric ray) origin. In this review, we evaluate the mainstays of cholinesterase inhibitory action of galanthamine and its various derivatives from the point of view of chemical and molecular aspects. PMID:25483718

Gulcan, Hayrettin O; Orhan, Ilkay E; Sener, Bilge

2015-01-01

188

Hirshfeld Surface Investigation of Structure-Directing Interactions within Dipicolinic Acid Derivatives  

PubMed Central

Six compounds based on dipicolinic acid esters have been synthesized and Hirshfeld surfaces used to investigate the structure-directing effects of functional groups in controlling their solid-state behavior. Compounds 1–4 are 4-bromo dipicolinic acid esters substituted with methyl, ethyl, propyl, and benzyl groups, respectively. The main structure-directing motif within 1–3 is a pairwise O···H interaction involving two carbonyl oxygen atoms and two aromatic H atoms. The introduction of bulky benzyl groups in 4 forces a significant change in the position of this interaction. Compounds 2 and 4 were used in Suzuki coupling reactions to prepare extended analogues 5 and 6, respectively, and their solid-state behavior was also studied using Hirshfeld surfaces. Extension of these dipicolinic acid esters results in the complete loss of the pairwise O···H interaction in 5, where the dominant structure-directing motifs are ?-based interactions. However, the pairwise O···H interaction reappears for the more flexible 6, demonstrating control of the solid-state structure of these dipicolinic acid derivatives through the choice of functional groups. PMID:25866487

2015-01-01

189

DNA-Binding Interaction Studies of Microwave Assisted Synthesized Sulfonamide Substituted 8-Hydroxyquinoline Derivatives.  

PubMed

Sulfonamide substituted 8-hydroxyquinoline derivatives were prepared using a microwave synthesizer. The interaction of sulfonamide substituted 8-hydroxyquinoline derivatives and their transition metal complexes with Plasmid (pUC 19) DNA and Calf Thymus DNA were investigated by UV spectroscopic studies and gel electrophoresis measurements. The interaction between ligand/metal complexes and DNA was carried out by increasing the concentration of DNA from 0 to 12 ?l in UV spectroscopic study, while the concentration of DNA in gel electrophoresis remained constant at 10 ?l. These studies supported the fact that, the complex binds to DNA by intercalation via ligand into the base pairs of DNA. The relative binding efficacy of the complexes to DNA was much higher than the binding efficacy of ligands, especially the complex of Cu-AHQMBSH had the highest binding ability to DNA. The mobility of the bands decreased as the concentration of the complex was increased, indicating that there was increase in the interaction between the metal ion and DNA. Complexes of AHQMBSH were excellent for DNA binding as compared to HQMABS. PMID:21773067

Dixit, Ritu B; Patel, Tarosh S; Vanparia, Satish F; Kunjadiya, Anju P; Keharia, Harish R; Dixit, Bharat C

2011-06-01

190

DNA-Binding Interaction Studies of Microwave Assisted Synthesized Sulfonamide Substituted 8-Hydroxyquinoline Derivatives  

PubMed Central

Sulfonamide substituted 8-hydroxyquinoline derivatives were prepared using a microwave synthesizer. The interaction of sulfonamide substituted 8-hydroxyquinoline derivatives and their transition metal complexes with Plasmid (pUC 19) DNA and Calf Thymus DNA were investigated by UV spectroscopic studies and gel electrophoresis measurements. The interaction between ligand/metal complexes and DNA was carried out by increasing the concentration of DNA from 0 to 12 ?l in UV spectroscopic study, while the concentration of DNA in gel electrophoresis remained constant at 10 ?l. These studies supported the fact that, the complex binds to DNA by intercalation via ligand into the base pairs of DNA. The relative binding efficacy of the complexes to DNA was much higher than the binding efficacy of ligands, especially the complex of Cu-AHQMBSH had the highest binding ability to DNA. The mobility of the bands decreased as the concentration of the complex was increased, indicating that there was increase in the interaction between the metal ion and DNA. Complexes of AHQMBSH were excellent for DNA binding as compared to HQMABS. PMID:21773067

Dixit, Ritu B.; Patel, Tarosh S.; Vanparia, Satish F.; Kunjadiya, Anju P.; Keharia, Harish R.; Dixit, Bharat C.

2011-01-01

191

New Amphiphilic Neamine Derivatives Active against Resistant Pseudomonas aeruginosa and Their Interactions with Lipopolysaccharides  

PubMed Central

The development of novel antimicrobial agents is urgently required to curb the widespread emergence of multidrug-resistant bacteria like colistin-resistant Pseudomonas aeruginosa. We previously synthesized a series of amphiphilic neamine derivatives active against bacterial membranes, among which 3?,6-di-O-[(2?-naphthyl)propyl]neamine (3?,6-di2NP), 3?,6-di-O-[(2?-naphthyl)butyl]neamine (3?,6-di2NB), and 3?,6-di-O-nonylneamine (3?,6-diNn) showed high levels of activity and low levels of cytotoxicity (L. Zimmermann et al., J. Med. Chem. 56:7691–7705, 2013). We have now further characterized the activity of these derivatives against colistin-resistant P. aeruginosa and studied their mode of action; specifically, we characterized their ability to interact with lipopolysaccharide (LPS) and to alter the bacterial outer membrane (OM). The three amphiphilic neamine derivatives were active against clinical colistin-resistant strains (MICs, about 2 to 8 ?g/ml), The most active one (3?,6-diNn) was bactericidal at its MIC and inhibited biofilm formation at 2-fold its MIC. They cooperatively bound to LPSs, increasing the outer membrane permeability. Grafting long and linear alkyl chains (nonyl) optimized binding to LPS and outer membrane permeabilization. The effects of amphiphilic neamine derivatives on LPS micelles suggest changes in the cross-bridging of lipopolysaccharides and disordering in the hydrophobic core of the micelles. The molecular shape of the 3?,6-dialkyl neamine derivatives induced by the nature of the grafted hydrophobic moieties (naphthylalkyl instead of alkyl) and the flexibility of the hydrophobic moiety are critical for their fluidifying effect and their ability to displace cations bridging LPS. Results from this work could be exploited for the development of new amphiphilic neamine derivatives active against colistin-resistant P. aeruginosa. PMID:24867965

Sautrey, Guillaume; Zimmermann, Louis; Deleu, Magali; Delbar, Alicia; Souza Machado, Luiza; Jeannot, Katy; Van Bambeke, Françoise; Buyck, Julien M.; Decout, Jean-Luc

2014-01-01

192

Cytotoxic and DNA-topoisomerase effects of lapachol amine derivatives and interactions with DNA.  

PubMed

The cytotoxic activity of amino (3a-e), aza-1-antraquinone (4a-e) lapachol derivatives against Ehrlich carcinoma and human K562 leukemia cells was investigated. Cell viability was determined using MTT assay, after 48 (Ehrlich) or 96 h (K562) of culture, and vincristine (for K562 leukemia) and quercetin (for Ehrlich carcinoma) were used as positive controls. The results showed dose-dependent growth-inhibiting activities and that the amino derivatives were active against the assayed cells, whereas the 4a-e derivatives were not. The allylamine derivative 3a was the most active against Ehrlich carcinoma, with IC50 = 16.94 +/- 1.25 microM, and against K562 leukemia, with IC50 = 14.11 +/- 1.39 microM. The analogous lawsone derivative, 5a, was also active against Ehrlich carcinoma (IC50 = 23.89 +/- 2.3 microM), although the 5d and 5e derivatives showed lower activity. The interaction between 3a-d and calf thymus DNA was investigated by fluorimetric titration and the results showed a hyperchromic effect indicating binding to DNA as presented of ethidium bromide, used as positive control. The inhibitory action on DNA-topoisomerase II-a was also evaluated by a relaxation assay of supercoiled DNA plasmid, and the etoposide (200 microM) was used as positive control. Significant inhibitory activities were observed for 3a-d at 200 microM and a partial inhibitory action was observed for lapachol and methoxylapachol. PMID:17713652

Esteves-Souza, A; Figueiredo, D V; Esteves, A; Câmara, C A; Vargas, M D; Pinto, A C; Echevarria, A

2007-10-01

193

Volumetric Ion Interaction Parameters for Single-Solute Aqueous Electrolyte Solutions at Various Temperatures  

NASA Astrophysics Data System (ADS)

The ion interaction approach developed by Pitzer allows the prediction of thermodynamic characteristics of mixed electrolyte solutions at various temperatures, if the respective parameters for each type of single electrolyte solution are known. Among such thermodynamic characteristics are the volumetric ones (density and apparent molal volumes). A database for the densities and the apparent molal volumes versus concentrations was developed at a temperature interval of 288.15-368.15 K using all available literature sources for each single electrolyte solution formed by various electrically neutral combinations of the following ions (Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, Cl-, Br-, HCO3-, CO32-, and SO42-). These are the most important ions for industrial solutions as well as for natural waters. Statistical treatment was applied to this database in order to discard poor data. The proper treatment of all sound quality apparent molal volumes, in a wide range of concentrations from infinite dilution through saturation, allowed us to compute sets of volumetric ion interaction parameters (V¯MX0, ?MX(0)V, ?MX(1)V, ?MX(2)V, and CMXV) at various temperatures in a 288.15-368.15 K temperature interval. The validity of the selected sets at various temperatures was demonstrated by a comparison of the experimental and calculated densities for multiple-solute electrolyte solutions containing NaCl, KCl, MgCl2, and CaCl2 with an ionic strength reaching 9.23 that resembled Dead Sea water.

Krumgalz, Boris S.; Pogorelskii, Rita; Sokolov, Alex; Pitzer, Kenneth S.

2000-09-01

194

Interaction between differentiating cell and niche-derived signals in hematopoietic progenitor maintenance  

PubMed Central

Summary Maintenance of a hematopoietic progenitor population requires extensive interaction with cells within a microenvironment or niche. In the Drosophila hematopoietic organ, niche-derived Hedgehog signaling maintains the progenitor population. Here we show that the hematopoietic progenitors also require a signal mediated by Adenosine deaminase growth factor A (Adgf-A) arising from differentiating cells that regulates extracellular levels of adenosine. The adenosine signal opposes the effects of Hedgehog signaling within the hematopoietic progenitor cells and the magnitude of the adenosine signal is kept in check by the level of Adgf-A secreted from differentiating cells. Our findings reveal signals arising from differentiating cells that are required for maintaining progenitor cell quiescence, and that function with the niche-derived signal in maintaining the progenitor state. Similar homeostatic mechanisms are likely to be utilized in other systems that maintain relatively large numbers of progenitors that are not all in direct contact with the cells of the niche. PMID:22196733

Mondal, Bama Charan; Mukherjee, Tina; Mandal, Lolitika; Evans, Cory J.; Sinenko, Sergey A.

2015-01-01

195

Experimental determination of the third derivative of G. I. enthalpic interaction.  

PubMed

The solute (i)-solute interaction in terms of enthalpy, H(i-i) (E)=N( partial differential(2)H(E)/ partial differentialn(i) (2))=(1-x(i))( partial differential(2)H(E)/ partial differentialn(i) partial differentialx(i)), the third derivative of G, was experimentally determined using a Thermal Activity Monitor isothermal titration calorimeter for aqueous solutions of 2-butoxyethanol (BE) and 1-propanol (1P). This was done using both calorimetric reference and sample vessels actively. We simultaneously titrate small and exactly equal amounts of solute i (=BE or 1P) into both cells which contain the binary mixtures at an average mole fraction, x(i), which differs by a small amount Deltax(i). The appropriate amount of titrant deltan(i) was chosen so that the quotient (deltaH(E)/deltan(i)) can be approximated as ( partial differentialH(E)/ partial differentialn(i)), and so that the scatter of the results is reasonable. deltaH(E) is the thermal response from an individual cell on titration, and we measure directly the difference in the thermal response between the two cells, Delta(deltaH(E)). The resulting quotient, Delta(deltaH(E))/deltan(i)/Deltax(i), can be approximated as ( partial differential(2)H(E)/ partial differentialn(i) partial differentialx(i)) and hence provides a direct experimental avenue for the enthalpy interaction function. We varied the value of Deltax(i) to seek its appropriate size. Since H(E) contains the first derivative of G with respect to T, the result is the third derivative quantity. Thus we present here a third derivative quantity directly determined experimentally for the first time. PMID:19063537

Westh, Peter; Inaba, Akira; Koga, Yoshikata

2008-12-01

196

Analytic second derivatives for general coupled-cluster and configuration-interaction models.  

PubMed

Analytic second derivatives of energy for general coupled-cluster (CC) and configuration-interaction (CI) methods have been implemented using string-based many-body algorithms. Wave functions truncated at an arbitrary excitation level are considered. The presented method is applied to the calculation of CC and CI harmonic frequencies and nuclear magnetic resonance chemical shifts up to the full CI level for some selected systems. The present benchmarks underline the importance of higher excitations in high-accuracy calculations. PMID:15267583

Kállay, Mihály; Gauss, Jürgen

2004-04-15

197

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

NASA Astrophysics Data System (ADS)

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).

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

2015-02-01

198

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

199

Quantifying Parameter Sensitivity, Interaction and Transferability in Hydrologically Enhanced Versions of Noah-LSM over Transition Zones  

NASA Technical Reports Server (NTRS)

We use sensitivity analysis to identify the parameters that are most responsible for shaping land surface model (LSM) simulations and to understand the complex 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 states and turbulent fluxes collected over nine sites in the US Southern Great Plains. We quantify changes in the pattern of sensitive parameters, the amount and nature of the interaction between parameters, and the covariance structure of the distribution of behavioral parameter sets. Using Sobol s total and first-order sensitivity indexes, we show that very few parameters directly control the variance of the model output. Significant parameter interaction occurs so that not only the optimal parameter values differ between models, but the relationships between parameters change. GW decreases parameter interaction and appears to improve model realism, especially at wetter sites. DV increases parameter interaction and decreases identifiability, implying it is overparameterized and/or underconstrained. A case study at a wet site shows GW has two functional modes: one that mimics STD and a second in which GW improves model function by decoupling direct evaporation and baseflow. Unsupervised classification of the posterior distributions of behavioral parameter sets cannot group similar sites based solely on soil or vegetation type, helping to explain why transferability between sites and models is not straightforward. This evidence suggests a priori assignment of parameters should also consider climatic differences.

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

2009-01-01

200

The use of the Flory-Huggins interaction parameter for the characterization of vacuum distillation residue fractions of mineral oils  

Microsoft Academic Search

Summary  The Flory-Huggins interaction parameter, ?\\u000a 1,2\\u000a ?\\u000a , was determined for a number of fractions separated from vacuum distillation residues of natural oils. Examined fractions\\u000a were used as liquid stationary phases in inverse gas chromatography. The chemical character of the fractions was discussed\\u000a in terms of the interaction parameter.

A. Voelkel I; J. Fall

1995-01-01

201

The use of the flory-huggins interaction parameter for the characterization of vacuum distillation residue fractions of mineral oils  

Microsoft Academic Search

Summary  The Flory-Huggins interaction parameter,?\\u000a 1,2,\\u000a ?\\u000a , was determined for a number of fractions separated from vacuum distillation residues of natural oils. Examined fractions\\u000a were used as liquid stationary phases in inverse gas chromatography. The chemical character of the fractions was discussed\\u000a in terms of the interaction parameter.

A. Voelkel; J. Fall

1995-01-01

202

A comparison of the BALTIMOS coupled climate model with atmospheric and sea surface parameters derived from AMSR-E  

NASA Astrophysics Data System (ADS)

The BALTEX Integrated Model System (BALTIMOS) coupled atmosphere ocean model was compared to passive microwave observations of the Advanced Microwave Scanning Radiometer (AMSR-E). Emphasis was put on quantifying the uncertainties associated with the different variables based on data screening both in the model and observations. Monthly means of three atmospheric parameters, as well as sea surface temperature, were compared for a period of 1 year. Sea ice extent was also derived from AMSR-E and compared to the model data on a daily basis. It is shown that the accuracy of the comparisons on a monthly mean basis is limited by precipitation screening. Out of the three atmospheric parameters, surface wind speed and water vapor column amount agree with the model data to within the accuracy of the comparison. The vertically integrated cloud liquid water content diagnosed from BALTIMOS is systematically higher than the liquid water content derived from satellite, even if potential systematic errors are accounted for. In terms of coupling, the two most relevant variables discussed are sea surface temperature and sea ice extent. The temporal extent of sea ice in the investigation area is well represented, as are the periods of the main growing and decay periods. The total sea ice cover appears to be underestimated by BALTIMOS, especially in the peak season between January and the beginning of March. The amplitude of the annual cycle of sea surface temperature in BALTIMOS appears to be too weak compared to the observations, leading to too cold sea surface temperatures in summer and too warm sea surface temperatures in winter. This might also partially explain the underestimation of sea ice cover by BALTIMOS.

Bennartz, Ralf; Lorenz, Philip; Jacob, Daniela

2014-11-01

203

Inclusion interactions and molecular microcapsule of Salvia sclarea L. essential oil with ?-cyclodextrin derivatives  

Microsoft Academic Search

The inclusion interactions of ?-cyclodextrin (?-CD), heptakis (2,6-di-methyl)-?-CD (DM-?-CD), mono[2-O-(2-hydroxyethyl)]-?-CD (2-HE-?-CD), and mono[2-O-(2-hydro-xypropyl)]-?-CD (2-HP-?-CD) with Salvia sclarea L. essential oil (SEO) were investigated by spectrofluorimetry, and the various factors affecting the inclusion process were\\u000a examined in detail. At the same time, the formation constants at different temperatures and the thermodynamic parameters (?H, ?S and ?G) were calculated. The molecular microcapsule

Xiang-Nan Tian; Zi-Tao Jiang; Rong Li

2008-01-01

204

Mean-Field Derivation of the Interacting Boson Model Hamiltonian and Exotic Nuclei  

SciTech Connect

A novel way of determining the Hamiltonian of the interacting boson model (IBM) is proposed. Based on the fact that the potential energy surface of the mean-field model, e.g., the Skyrme model, can be simulated by that of the IBM, parameters of the IBM Hamiltonian are obtained. By this method, the multifermion dynamics of surface deformation can be mapped, in a good approximation, onto a boson system. The validity of this process is examined for Sm and Ba isotopes, and an application is presented to an unexplored territory of the nuclear chart, namely, the right lower corner of {sup 208}Pb.

Nomura, Kosuke; Shimizu, Noritaka [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Otsuka, Takaharu [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); RIKEN, Hirosawa, Wako-shi, Saitama 351-0198 (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, 48824 Michigan (United States)

2008-10-03

205

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

206

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

207

Investigations on stabilities and intermolecular interactions of different naphthalene derivatives dimers by using B3LYP and M06-2X density functional calculations  

NASA Astrophysics Data System (ADS)

In this paper, the stabilities and hydrogen bond interactions of 4-chloro-1-naphthol, 1-hydrox-ynaphthalene and 1,4-dihydroxynaphthalene dimers have been theoretically investigated by means of study on binding energies with nonlocal hybrid three-parameter Lee-Yang-Parr, B3LYP, and M06-class functional calculations. Calculations on dimers aim to provide as a test of the efficacy of M06 calculations for intermolecular interaction calculations and more strongly bound systems. For hydroxyl- and halo-substituted derivatives of naphthalene, total electronic energies, their correction for the zero point vibrational energies with some calculated thermodynamic properties and their relative differences are together in order to discuss the rotamer structures. Static (hyper) polarizabilities and the electric dipole moments, frontier molecular orbital energy gaps and the relationships between them have been interpreted. Generally, they are seen that the calculated geometric parameters and spectral results were in a good agreement with the corresponding experimental data.

Karakaya, M.; Çiçek, A.; Ucun, F.; Yildiz, M.

2014-12-01

208

A global climatology of stratospheric aerosol size distribution parameters derived from SAGE II data over the period 1984–2000: 1. Methodology and climatological observations  

Microsoft Academic Search

A global climatology has been derived for different parameters characterizing the size distribution of stratospheric aerosols; the particle number density, median radius, and mode width of the particle distribution were assumed to be lognormal. Those parameters were retrieved by applying an original optical inversion scheme on Stratospheric Aerosol and Gas Experiment (SAGE) II aerosol extinction profiles spanning from 1984 to

Christine Bingen; Didier Fussen; Filip Vanhellemont

2004-01-01

209

A global climatology of stratospheric aerosol size distribution parameters derived from SAGE II data over the period 1984-2000: 1. Methodology and climatological observations  

Microsoft Academic Search

A global climatology has been derived for different parameters characterizing the size distribution of stratospheric aerosols; the particle number density, median radius, and mode width of the particle distribution were assumed to be lognormal. Those parameters were retrieved by applying an original optical inversion scheme on Stratospheric Aerosol and Gas Experiment (SAGE) II aerosol extinction profiles spanning from 1984 to

Christine Bingen; Didier Fussen; Filip Vanhellemont

2004-01-01

210

Claridge et al.: Model based inversion for deriving maps of histological parameters characteristic of cancer 1 Abstract--A model-based inversion method was used to  

E-print Network

Claridge et al.: Model based inversion for deriving maps of histological parameters characteristic of histological parameters from multispectral images of the colon and to examine their potential.04. Validation on ex vivo images demonstrated that parametric maps show gross correspondence with histological

Claridge, Ela

211

Concerted Mitigation of O···H and C(?)···H Interactions Prospects Sixfold Gain in Optical Nonlinearity of Ionic Stilbazolium Derivatives.  

PubMed

DAST (4-dimethylamino-N-methyl-4-stilbazolium tosylate) is the most commercially successful organic nonlinear optical (NLO) material for frequency-doubling, integrated optics, and THz wave applications. Its success is predicated on its high optical nonlinearity with concurrent sufficient thermal stability. Many chemical derivatives of DAST have therefore been developed to optimize their properties; yet, to date, none have surpassed the overall superiority of DAST for NLO photonic applications. This is perhaps because DAST is an ionic salt wherein its NLO-active cation is influenced by multiple types of subtle intermolecular forces that are hard to quantify, thus, making difficult the molecular engineering of better functioning DAST derivatives. Here, we establish a model parameter, ?inter, that isolates the influence of intermolecular interactions on second-order optical nonlinearity in DAST and its derivatives, using second-harmonic generation (SHG) as a qualifier; by systematically mapping intercorrelations of all possible pairs of intermolecular interactions to ?inter, we uncover a relationship between concerted intermolecular interactions and SHG output. This correlation reveals that a sixfold gain in the intrinsic second-order NLO performance of DAST is possible, by eliminating the identified interactions. This prediction offers the first opportunity to systematically design next-generation DAST-based photonic device nanotechnology to realize such a prospect. PMID:25654641

Cole, Jacqueline M; Lin, Tze-Chia; Edwards, Alison J; Piltz, Ross O; Depotter, Griet; Clays, Koen; Lee, Seung-Chul; Kwon, O-Pil

2015-03-01

212

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 Region Experiment (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 4-km visible (0.65 micrometer) and 8-km infrared window (11.5 micrometer) 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 062 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 wer 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 temperature and cloud thickness 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 advanced very high resolution radiometer (AVHRR) data. Inhomogeneities in the cloud fields result in uneven cloud shading that apparently causes the occurrence of anomalously dark, cloud pixels in the GOES data. These shading effects complicate the interpretation of the satellite data. The results highlight the need for additional study or cirrus cloud scattering processes and remote sensing techniques.

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

1996-01-01

213

Spatial Variations in CO2 Mixing Ratios Over a Heterogenous Landscape - Linking Airborne Measurements With Remote Sensing Derived Biophysical Parameters  

NASA Astrophysics Data System (ADS)

North American terrestrial ecosystems are major sources and sinks of carbon. Precise measurement of atmospheric CO2 concentrations plays an important role in the development and testing of carbon cycle models quantifying the influence of terrestrial CO2 exchange on the North American carbon budget. During the summer 2004 Intercontinental Chemical Transport Experiment North America (INTEX-NA) campaign, regional scale in-situ measurements of atmospheric CO2 were made from the NASA DC-8 affording the opportunity to explore how land surface heterogeneity relates to the airborne observations utilizing remote-sensing data products and GIS-based methods. These 1 Hz data reveal the seasonal biospheric uptake of CO2 over portions of the U.S. continent, especially east of 90°W below 2 km, compared to higher mixing ratios over water as well as within the upper troposphere where well-mixed, aged air masses were sampled. In this study, we use several remote sensing derived biophysical parameters from the LANDSAT, NOAA AVHRR, and MODIS sensors to specify spatiotemporal patterns of land use cover and vegetation characteristics for linking the airborne measurements of CO2 data with terrestrial sources of carbon. Also, CO2 flux footprint outputs from a 3-D Lagrangian atmospheric model have been integrated with satellite remote sensing data to infer CO2 variations across heterogeneous landscapes. In examining the landscape mosaic utilizing these available tools, preliminary results suggest that the lowest CO2 mixing ratios observed during INTEX-NA were over agricultural fields in Illinois dominated by corn then secondarily soybean crops. Low CO2 concentrations are attributable to sampling during the peak growing season over such C4 plants as corn having a higher photosynthetic rate via the C4-dicarboxylic acid pathway of carbon fixation compared to C3 plants such as soybeans. In addition to LANDSAT derived land cover data, results from comparisons of the airborne CO2 observations with vegetation indices of NDVI and EVI derived from MODIS data were used. Higher CO2 mixing ratios anti-correlated with the vegetation indices derived from MODIS data were observed. This is attributable to the photosynthetic uptake of CO2 by plants and convective mixing of the atmosphere. Details of satellite data characteristics related with the in-situ CO2 measurements will be presented.

Choi, Y.; Vadrevu, K. P.; Vay, S. A.; Woo, J.

2006-12-01

214

Comparative studies of different concretes on the basis of some photon interaction parameters.  

PubMed

Different photon interaction parameters viz. linear attenuation coefficient, mass attenuation coefficient, penetration depth, equivalent atomic number, exposure buildup factor have been computed for seven different concretes (ordinary, hematite-serpentine, ilmenite-limonite, basalt-magnetite, ilmenite, steel-scrap and steel magnetite) in the energy region of 0.015-15.0MeV. The computed parameters were studied as a function of incident photon energy, chemical composition and penetration depth of the selected concretes. It has been observed that among the selected concretes, steel magnetite offers maximum value for linear attenuation coefficient, mass attenuation coefficient, equivalent atomic number and least values in terms of penetration depth equivalent to mean free path and exposure buildup factors. Hence, it is concluded that it offers better shielding among the selected concretes. It is expected that in case of any nuclear accident, the presented buildup factor data may be helpful in estimating the effective dose given to people living in buildings constructed from one of the selected concretes. PMID:21820906

Kaur, Updesh; Sharma, J K; Singh, Parjit S; Singh, Tejbir

2012-01-01

215

Salmonella?infected crypt?derived intestinal organoid culture system for host–bacterial interactions  

PubMed Central

Abstract The in vitro analysis of bacterial–epithelial interactions in the intestine has been hampered by a lack of suitable intestinal epithelium culture systems. Here, we report a new experimental model using an organoid culture system to study pathophysiology of bacterial–epithelial interactions post Salmonella infection. Using crypt?derived mouse intestinal organoids, we were able to visualize the invasiveness of Salmonella and the morphologic changes of the organoids. Importantly, we reported bacteria?induced disruption of epithelial tight junctions in the infected organoids. In addition, we showed the inflammatory responses through activation of the NF??B pathway in the organoids. Moreover, our western blot, PCR, and immunofluorescence data demonstrated that stem cell markers (Lgr5 and Bmi1) were significantly decreased by Salmonella infection (determined using GFP?labeled Lgr5 organoids). For the first time, we created a model system that recapitulated a number of observations from in vivo studies of the Salmonella?infected intestine, including bacterial invasion, altered tight junctions, inflammatory responses, and decreased stem cells. We have demonstrated that the Salmonella?infected organoid culture system is a new experimental model suitable for studying host–bacterial interactions. PMID:25214524

Zhang, Yong?Guo; Wu, Shaoping; Xia, Yinglin; Sun, Jun

2014-01-01

216

Probing protein structure and dynamics by second-derivative ultraviolet absorption analysis of cation–? interactions  

PubMed Central

We describe an alternate approach for studying protein structure using the detection of ultraviolet (UV) absorbance peak shifts of aromatic amino acid side chains induced by the presence of salts. The method is based on the hypothesis that salt cations (Li+, Na+, and Cs+) of varying sizes can differentially diffuse through protein matrices and interact with benzyl, phenyl, and indole groups through cation–? interactions. We have investigated the potential of this method to probe protein dynamics by measuring high resolution second-derivative UV spectra as a function of salt concentration for eight proteins of varying physical and chemical properties and the N-acetylated C-ethyl esterified amino acids to represent totally exposed side chains. We show that small shifts in the wavelength maxima for Phe, Tyr, and Trp in the presence of high salt concentrations can be reliably measured and that the magnitude and direction of the peak shifts are influenced by several factors, including protein size, charge, and the local environment and solvent accessibility of the aromatic groups. Evaluating the empirical UV spectral data in light of known protein structural information shows that probing cation–? interactions in proteins reveals unique information about the influence of structure on aromatic side chain spectroscopic behavior. PMID:16963649

Lucas, Laura H.; Ersoy, Baran A.; Kueltzo, Lisa A.; Joshi, Sangeeta B.; Brandau, Duane T.; Thyagarajapuram, Nagarajan; Peek, Laura J.; Middaugh, C. Russell

2006-01-01

217

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

218

Interactions among thermal parameters determine offspring sex under temperature-dependent sex determination  

PubMed Central

In many animals, temperatures experienced by developing embryos determine offspring sex (e.g. temperature-dependent sex determination, TSD), but most studies focus strictly on the effects of mean temperature, with little emphasis on the importance of thermal fluctuations. In the jacky dragon (Amphibolurus muricatus), an Australian lizard with TSD, data from nests in the field demonstrate that offspring sex ratios are predictable from thermal fluctuations but not from mean nest temperatures. To clarify this paradox, we incubated eggs in a factorial experiment with two levels of mean temperature and three levels of diel fluctuation. We show that offspring sex is determined by an interaction between these critical thermal parameters. Intriguingly, because these two thermal descriptors shift in opposing directions throughout the incubation season, this interactive effect inhibits seasonal shifts in sex ratio. Hence, our results suggest that TSD can yield offspring sex ratios that resemble those produced under genotypic sex-determining systems. These findings raise important considerations for understanding the diversity of TSD reaction norms, for designing experiments that evaluate the evolutionary significance of TSD, and for predicting sex ratios under past and future climate change scenarios. PMID:20685704

Warner, Daniel A.; Shine, Richard

2011-01-01

219

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

Microsoft Academic Search

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

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

2007-01-01

220

Differential reconstructed gene interaction networks for deriving toxicity threshold in chemical risk assessment  

PubMed Central

Background Pathway alterations reflected as changes in gene expression regulation and gene interaction can result from cellular exposure to toxicants. Such information is often used to elucidate toxicological modes of action. From a risk assessment perspective, alterations in biological pathways are a rich resource for setting toxicant thresholds, which may be more sensitive and mechanism-informed than traditional toxicity endpoints. Here we developed a novel differential networks (DNs) approach to connect pathway perturbation with toxicity threshold setting. Methods Our DNs approach consists of 6 steps: time-series gene expression data collection, identification of altered genes, gene interaction network reconstruction, differential edge inference, mapping of genes with differential edges to pathways, and establishment of causal relationships between chemical concentration and perturbed pathways. A one-sample Gaussian process model and a linear regression model were used to identify genes that exhibited significant profile changes across an entire time course and between treatments, respectively. Interaction networks of differentially expressed (DE) genes were reconstructed for different treatments using a state space model and then compared to infer differential edges/interactions. DE genes possessing differential edges were mapped to biological pathways in databases such as KEGG pathways. Results Using the DNs approach, we analyzed a time-series Escherichia coli live cell gene expression dataset consisting of 4 treatments (control, 10, 100, 1000 mg/L naphthenic acids, NAs) and 18 time points. Through comparison of reconstructed networks and construction of differential networks, 80 genes were identified as DE genes with a significant number of differential edges, and 22 KEGG pathways were altered in a concentration-dependent manner. Some of these pathways were perturbed to a degree as high as 70% even at the lowest exposure concentration, implying a high sensitivity of our DNs approach. Conclusions Findings from this proof-of-concept study suggest that our approach has a great potential in providing a novel and sensitive tool for threshold setting in chemical risk assessment. In future work, we plan to analyze more time-series datasets with a full spectrum of concentrations and sufficient replications per treatment. The pathway alteration-derived thresholds will also be compared with those derived from apical endpoints such as cell growth rate. PMID:24268022

2013-01-01

221

Glionitrin A, an antibiotic-antitumor metabolite derived from competitive interaction between abandoned mine microbes  

SciTech Connect

The nutrient conditions present in abandoned coal mine drainages create an extreme environment where defensive and offensive microbial interactions could be critical for survival and fitness. Coculture of a mine drainage-derived Sphingomonas bacterial strain, KMK-001, and a mine drainage-derived Aspergillus fumigatus fungal strain, KMC-901, resulted in isolation of a new diketopiperazine disulfide, glionitrin A (1). Compound 1 was not detected in monoculture broths of KMK-001 or KMC-901. The structure of 1, a (3S,10aS) diketopiperazine disulfide containing a nitro aromatic ring, was based on analysis of MS, NMR, and circular dichroism spectra and confirmed by X-ray crystal data. Glionitrin A displayed significant antibiotic activity against a series of microbes including methicillin-resistant Staphylococcus aureus. An in vitro MTT cytotoxicity assay revealed that 1 had potent submicromolar cytotoxic activity against four human cancer cell lines: HCT-116, A549, AGS, and DU145. The results provide further evidence that microbial coculture can produce novel biologically relevant molecules.

Park, H.B.; Kown, H.C.; Lee, C.H.; Yang, H.O. [Korean Institute of Science & Technology KIST, Kangnung (Republic of Korea)

2009-02-15

222

Derived Properties of Warm Marine Low Clouds over the Southern Ocean: Precipitation Susceptibility and Sensitivity to Environmental Parameters (Invited)  

NASA Astrophysics Data System (ADS)

The Southern Ocean is one of the cloudiest regions on Earth and the majority of this cloudiness is in the form of shallow convective clouds based in the marine boundary layer. Our understanding of the processes that modulate marine boundary layer clouds in the Southern Ocean remain poor and models of the Earth's climate system remain challenged to replicate their occurrence. The fractional rate of change of precipitation rate in terms of the fractional rate of change of cloud droplet number concentration defines the precipitation susceptibility (S0). In marine boundary layer clouds, S0 is an important diagnostic quantity for understanding the microphysical processes that control cloud longevity, radiative forcing, and aerosol effects. We explore the statistics of S0 over the Southern Ocean using cloud properties derived from an optimal estimation-based algorithm specifically designed for this purpose that uses Cloudsat radar reflectivity profiles, 94 GHz microwave brightness temperature, and 3 MODIS visible channels. The algorithm assumes a bimodal droplet distribution consisting of cloud and precipitation modes. The sensitivity of S0 to large-scale environmental parameters such as low-level wind speed, static stability, and large-scale vertical motion will be examined. In addition sensitivity to the background aerosol optical depth will be considered using MODIS products.

Mace, G. G.; Ferguson, T.; Avey, S.; Benson, S.

2013-12-01

223

A compilation of rate parameters of water-mineral interaction kinetics for application to geochemical modeling  

USGS Publications Warehouse

Geochemical reaction path modeling is useful for rapidly assessing the extent of water-aqueous-gas interactions both in natural systems and in industrial processes. Modeling of some systems, such as those at low temperature with relatively high hydrologic flow rates, or those perturbed by the subsurface injection of industrial waste such as CO2 or H2S, must account for the relatively slow kinetics of mineral-gas-water interactions. We have therefore compiled parameters conforming to a general Arrhenius-type rate equation, for over 70 minerals, including phases from all the major classes of silicates, most carbonates, and many other non-silicates. The compiled dissolution rate constants range from -0.21 log moles m-2 s-1 for halite, to -17.44 log moles m-2 s-1 for kyanite, for conditions far from equilibrium, at 25 ?C, and pH near neutral. These data have been added to a computer code that simulates an infinitely well-stirred batch reactor, allowing computation of mass transfer as a function of time. Actual equilibration rates are expected to be much slower than those predicted by the selected computer code, primarily because actual geochemical processes commonly involve flow through porous or fractured media, wherein the development of concentration gradients in the aqueous phase near mineral surfaces, which results in decreased absolute chemical affinity and slower reaction rates. Further differences between observed and computed reaction rates may occur because of variables beyond the scope of most geochemical simulators, such as variation in grain size, aquifer heterogeneity, preferred fluid flow paths, primary and secondary mineral coatings, and secondary minerals that may lead to decreased porosity and clogged pore throats.

Palandri, James L.; Kharaka, Yousif K.

2004-01-01

224

Betulin derivatives impair Leishmania braziliensis viability and host-parasite interaction.  

PubMed

Leishmaniasis is a public health problem in tropical and subtropical areas of the world, including Venezuela. The incidence of treatment failure and the number of cases with Leishmania-HIV co-infection underscore the importance of developing alternative, economical and effective therapies against this disease. The work presented here analyzed whether terpenoids derived from betulin are active against New World Leishmania parasites. Initially we determined the concentration that inhibits the growth of these parasites by 50% or IC50, and subsequently evaluated the chemotactic effect of four compounds with leishmanicidal activity in the sub-micromolar and micromolar range. That is, we measured the migratory capacity of Leishmania (V.) braziliensis in the presence of increasing concentrations of compounds. Finally, we evaluated their cytotoxicity against the host cell and their effect on the infectivity of L. (V.) braziliensis. The results suggest that (1) compounds 14, 17, 18, 25 and 27 are active at concentrations lower than 10 ?M; (2) compound 26 inhibits parasite growth with an IC50 lower than 1 ?M; (3) compounds 18, 26 and 27 inhibit parasite migration at pico- to nanomolar concentrations, suggesting that they impair host-parasite interaction. None of the tested compounds was cytotoxic against J774.A1 macrophages thus indicating their potential as starting points to develop compounds that might affect parasite-host cell interaction, as well as being leishmanicidal. PMID:25240731

Alcazar, Wilmer; López, Adrian Silva; Alakurtti, Sami; Tuononen, Maija-Liisa; Yli-Kauhaluoma, Jari; Ponte-Sucre, Alicia

2014-11-01

225

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

226

Polymer-Drug Interactions in Tyrosine-Derived Triblock Copolymer Nanospheres: a Computational Modeling Approach  

PubMed Central

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, anti-cancer drug paclitaxel and pre-hormone 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

227

End-to-end distance distribution in fluorescent derivatives of bradykinin in interaction with lipid vesicles.  

PubMed

Cellular membranes have relevant roles in processes related to proteases like human kallikreins and cathepsins. As enzyme and substrate may interact with cell membranes and associated co-factors, it is important to take into account the behavior of peptide substrates in the lipid environment. In this paper we report an study based on energy transfer in two bradykinin derived peptides labeled with the donor-acceptor pair Abz/Eddnp (ortho-aminobenzoic acid/N-[2,4-dinitrophenyl]-ethylenediamine). Time-resolved fluorescence experiments were performed in phosphate buffer and in the presence of large unilamelar vesicles of phospholipids, and of micelles of sodium dodecyl sulphate (SDS). The decay kinetics were analyzed using the program CONTIN to obtain end-to-end distance distribution functions f(r). Despite of the large difference in the number of residues the end-to-end distance of the longer peptide (9 amino acid residues) is only 20?% larger than the values obtained for the shorter peptide (5 amino acid residues). The proline residue, in position 4 of the bradykinin sequence promotes a turn in the longer peptide chain, shortening its end-to-end distance. The surfactant SDS has a strong disorganizing effect, substantially broadening the distance distributions, while temperature increase has mild effects in the flexibility of the chains, causing small increase in the distribution width. The interaction with phospholipid vesicles stabilizes more compact conformations, decreasing end-to-end distances in the peptides. Anisotropy experiments showed that rotational diffusion was not severely affected by the interaction with the vesicles, suggesting a location for the peptides in the surface region of the bilayer, a result consistent with small effect of lipid phase transition on the peptides conformations. PMID:22488046

Montaldi, L R; Berardi, M; Souza, E S; Juliano, L; Ito, A S

2012-07-01

228

Lumpy - an interactive Lumped Parameter Modeling code based on MS Access and MS Excel.  

NASA Astrophysics Data System (ADS)

Several tracers for dating groundwater (18O/2H, 3H, CFCs, SF6, 85Kr) need lumped parameter modeling (LPM) to convert measured values into numbers with unit time. Other tracers (T/3He, 39Ar, 14C, 81Kr) allow the computation of apparent ages with a mathematical formula using radioactive decay without defining the age mixture that any groundwater sample represents. Also interpretation of the latter profits significantly from LPM tools that allow forward modeling of input time series to measurable output values assuming different age distributions and mixtures in the sample. This talk presents a Lumped Parameter Modeling code, Lumpy, combining up to two LPMs in parallel. The code is standalone and freeware. It is based on MS Access and Access Basic (AB) and allows using any number of measurements for both input time series and output measurements, with any, not necessarily constant, time resolution. Several tracers, also comprising very different timescales like e.g. the combination of 18O, CFCs and 14C, can be modeled, displayed and fitted simultaneously. Lumpy allows for each of the two parallel models the choice of the following age distributions: Exponential Piston flow Model (EPM), Linear Piston flow Model (LPM), Dispersion Model (DM), Piston flow Model (PM) and Gamma Model (GM). Concerning input functions, Lumpy allows delaying (passage through the unsaturated zone) shifting by a constant value (converting 18O data from a GNIP station to a different altitude), multiplying by a constant value (geochemical reduction of initial 14C) and the definition of a constant input value prior to the input time series (pre-bomb tritium). Lumpy also allows underground tracer production (4He or 39Ar) and the computation of a daughter product (tritiugenic 3He) as well as partial loss of the daughter product (partial re-equilibration of 3He). These additional parameters and the input functions can be defined independently for the two sub-LPMs to represent two different recharge areas. For a user defined choice of up to five parameters (mean residence times and dispersion parameters of the two sub-LPM plus the mixing ratios of the two models) the best fit can be determined. Fits can be assessed using different methods for the Goodness Of Fit. Input and output data are send to MS Excel for interactive display of modeling result and comparison with measurements. Excel only serves as data display; computations are performed in AB throughout. Lumpy allows display of time series and any combination of tracer vs. tracer plot. In the latter, the possible output data space assessable by the input variables can be displayed, to check if any of the model combinations under consideration is able to explain the measured data. Comparison and fit to measurements is possible after each of the two sub-models and after mixing these two. The talk will demonstrate the usefulness of this approach with examples from the Croatian Karst (Babinka 2007), the Fischa tracer test (Stolp et al., 2010) and the 30 years monthly tritium time series of the Danube (Aggarwal et al., 2010).

Suckow, A.

2012-04-01

229

Tritium plasma experiment: parameters and potentials for fusion plasma-wall interaction studies.  

PubMed

The tritium plasma experiment (TPE) is a unique facility devoted to experiments on the behavior of deuterium/tritium in toxic (e.g., beryllium) and radioactive materials for fusion plasma-wall interaction studies. A Langmuir probe was added to the system to characterize the plasma conditions in TPE. With this new diagnostic, we found the achievable electron temperature ranged from 5.0 to 10.0 eV, the electron density varied from 5.0 × 10(16) to 2.5 × 10(18) m(-3), and the ion flux density varied between 5.0 × 10(20) to 2.5 × 10(22) m(-2) s(-1) along the centerline of the plasma. A comparison of these plasma parameters with the conditions expected for the plasma facing components (PFCs) in ITER shows that TPE is capable of achieving most (?800 m(2) of 850 m(2) total PFCs area) of the expected ion flux density and electron density conditions. PMID:21895244

Shimada, Masashi; Kolasinski, Robert D; Sharpe, J Phillip; Causey, Rion A

2011-08-01

230

Dynamic interactions between hydrogeological and exposure parameters in daily dose prediction under uncertainty and temporal variability.  

PubMed

We study the time dependent interaction between hydrogeological and exposure parameters in daily dose predictions due to exposure of humans to groundwater contamination. Dose predictions are treated stochastically to account for an incomplete hydrogeological and geochemical field characterization, and an incomplete knowledge of the physiological response. We used a nested Monte Carlo framework to account for uncertainty and variability arising from both hydrogeological and exposure variables. Our interest is in the temporal dynamics of the total dose and their effects on parametric uncertainty reduction. We illustrate the approach to a HCH (lindane) pollution problem at the Ebro River, Spain. The temporal distribution of lindane in the river water can have a strong impact in the evaluation of risk. The total dose displays a non-linear effect on different population cohorts, indicating the need to account for population variability. We then expand the concept of Comparative Information Yield Curves developed earlier (see de Barros et al. [29]) to evaluate parametric uncertainty reduction under temporally variable exposure dose. Results show that the importance of parametric uncertainty reduction varies according to the temporal dynamics of the lindane plume. The approach could be used for any chemical to aid decision makers to better allocate resources towards reducing uncertainty. PMID:24011618

Kumar, Vikas; de Barros, Felipe P J; Schuhmacher, Marta; Fernàndez-Garcia, Daniel; Sanchez-Vila, Xavier

2013-12-15

231

Tritium plasma experiment: Parameters and potentials for fusion plasma-wall interaction studies  

SciTech Connect

The tritium plasma experiment (TPE) is a unique facility devoted to experiments on the behavior of deuterium/tritium in toxic (e.g., beryllium) and radioactive materials for fusion plasma-wall interaction studies. A Langmuir probe was added to the system to characterize the plasma conditions in TPE. With this new diagnostic, we found the achievable electron temperature ranged from 5.0 to 10.0 eV, the electron density varied from 5.0 x 10{sup 16} to 2.5 x 10{sup 18} m{sup -3}, and the ion flux density varied between 5.0 x 10{sup 20} to 2.5 x 10{sup 22} m{sup -2} s{sup -1} along the centerline of the plasma. A comparison of these plasma parameters with the conditions expected for the plasma facing components (PFCs) in ITER shows that TPE is capable of achieving most ({approx}800 m{sup 2} of 850 m{sup 2} total PFCs area) of the expected ion flux density and electron density conditions.

Shimada, Masashi; Sharpe, J. Phillip [Fusion Safety Program, Idaho National Laboratory, Idaho Falls, Idaho 83415 (United States); Kolasinski, Robert D.; Causey, Rion A. [Hydrogen and Metallurgical Science Department, Sandia National Laboratories, Livermore, California 94551 (United States)

2011-08-15

232

Tritium Plasma Experiment (TPE) - parameters and potentials for fusion plasma-wall interaction studies  

SciTech Connect

The Tritium plasma experiment (TPE) is a unique facility devoted to experiments on the behavior of deuterium/tritium in toxic (e.g. beryllium) and radioactive materials for fusion plasma-wall interaction (PWI) studies. A Langmuir probe was added to the system to characterize the plasma conditions in TPE. With this new diagnostic, we found the achievable electron temperature ranged from 5.0 to 10.0 eV, the electron density varied from 5.0 x 10{sup 16} to 2.5 x 10{sup 18} m{sup -3}, and the ion flux density varied between 5.0 x 10{sup 20} to 2.5 x 10{sup 22} m{sup -2}s{sup -1} along the centerline of the plasma. A comparison of these plasma parameters with the conditions expected for the plasma facing components (PFCs) in ITER shows that TPE is capable of achieving most (approximately 800 m{sup 2} of 850 m{sup 2} total PFCs area) of the expected ion flux density and electron density conditions.

Masashi Shimada; Robert D. Kolasinski; J. Phillip Sharpe; Rion A. Causey

2011-08-01

233

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

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

2013-03-15

234

Research on interactive influences of parameters on T-shaped cold ring rolling by 3d-FE numerical simulation  

Microsoft Academic Search

Cold ring rolling is a much complex physical process with multi-factors. Two forming parameters, the feed rate of mandrel\\u000a and the rotational speed of main roll, affect the quality of deformed ring significantly and the feed amount per revolution\\u000a of ring in the form of their ratio. By their ratio, the interactive effects of the two forming parameters on the

Lanyun Li; He Yang; Lianggang Guo; Zhichao Sun

2007-01-01

235

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,...

Khodam-Mohammadi, A; Sheykhi, A

2014-01-01

236

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

237

Relationship between Levels of Brain-Derived Neurotrophic Factor and Metabolic Parameters in Patients with Type 2 Diabetes Mellitus  

PubMed Central

Background and Aim. Studies have suggested that brain-derived neurotrophic factor (BDNF) plays a role in glucose and lipid metabolism and inflammation. The aim of this study was to evaluate the relationship between serum BDNF levels and various metabolic parameters and inflammatory markers in patients with type 2 diabetes mellitus (T2DM). Materials and Methods. The study included 88 T2DM patients and 33 healthy controls. Fasting blood samples were obtained from the patients and the control group. The serum levels of BDNF were measured with an ELISA kit. The current paper introduces a receiver-operating characteristic (ROC) generalization curve to identify cut-off for the BDNF values in type 2 diabetes patients. Results. The serum levels of BDNF were significantly higher in T2DM patients than in the healthy controls (206.81?±?107.32?pg/mL versus 130.84?±?59.81?pg/mL; P < 0.001). They showed a positive correlation with the homeostasis model assessment of insulin resistance (HOMA-IR) (r = 0.28; P < 0.05), the triglyceride level (r = 0.265; P < 0.05), and white blood cell (WBC) count (r = 0.35; P < 0.001). In logistic regression analysis, age (P < 0.05), body mass index (BMI) (P < 0.05), C-reactive protein (CRP) (P < 0.05), and BDNF (P < 0.01) were independently associated with T2DM. In ROC curve analysis, BDNF cut-off was 137. Conclusion. The serum BDNF level was higher in patients with T2DM. The BDNF had a cut-off value of 137. The findings suggest that BDNF may contribute to glucose and lipid metabolism and inflammation. PMID:25587547

Boyuk, Banu; Degirmencioglu, Serife; Atalay, Hande; Guzel, Savas; Acar, Ayse; Celebi, Aslan; Ekizoglu, Ismail; Simsek, Caglar

2014-01-01

238

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

239

Lens Epithelium-derived Growth Factor/p75 Interacts with the Transposase-derived DDE Domain of PogZ*S?  

PubMed Central

Lens epithelium-derived growth factor/p75 (LEDGF/p75) is a prominent cellular interaction partner of human immunodeficiency virus-1 (HIV-1) integrase, tethering the preintegration complex to the host chromosome. In light of the development of LEDGF/p75-integrase interaction inhibitors, it is essential to understand the cell biology of LEDGF/p75. We identified pogZ as new cellular interaction partner of LEDGF/p75. Analogous to lentiviral integrase, pogZ, a domesticated transposase, carries a DDE domain, the major determinant for LEDGF/p75 interaction. Using different in vitro and in vivo approaches, we corroborated the interaction between the C terminus of LEDGF/p75 and the DDE domain of pogZ, revealing an overlap in the binding of pogZ and HIV-1 integrase. Competition experiments showed that integrase is efficient in displacing pogZ from LEDGF/p75. Moreover, pogZ does not seem to play a role as a restriction factor of HIV. The finding that LEDGF/p75 is capable of interacting with a DDE domain protein that is not a lentiviral integrase points to a profound role of LEDGF/p75 in DDE domain protein function. PMID:19244240

Bartholomeeusen, Koen; Christ, Frauke; Hendrix, Jelle; Rain, Jean-Christophe; Emiliani, Stéphane; Benarous, Richard; Debyser, Zeger; Gijsbers, Rik; De Rijck, Jan

2009-01-01

240

Immunobiology Multidirectional interactions are bridging human NK cells with plasmacytoid and monocyte-derived dendritic cells during innate immune responses  

Microsoft Academic Search

During innate immune responses, natu- ral killer (NK) cells may interact with both plasmacytoid dendritic cells (pDCs) and monocyte-derived dendritic cells (MDDCs). We show that freshly isolated NK cells promote the release by pDCs of IFN-, in a CpG-dependent manner, whereas they induce IL-6 production in a CpG-independent manner. In turn pDC- derived IFN- up-regulates NK-mediated killing, whereas IL-6 could

Mariella Della Chiesa; Chiara Romagnani; Andreas Thiel; Lorenzo Moretta; Alessandro Moretta

2006-01-01

241

Interaction between chitosan and uranyl ions. Role of physical and physicochemical parameters on the kinetics of sorption  

SciTech Connect

This work corresponds to the first part of our studies on the interactions between chitosan particles dispersed in water and uranyl ions. The measurements were obtained by ICP, and we considered the role of various physical and physicochemical parameters related to chitosan. We showed that the crystallinity, the particle dimensions, and the swelling in water of chitosan are parameters which are connected together and govern the kinetic laws of metal diffusion and sorption. The molecular mobility of the polymer chains is then essential parameter. 31 refs., 5 figs., 3 tabs.

Piron, E. [Universite Claude Bernard, Villeurbanne (France)] [Universite Claude Bernard, Villeurbanne (France); [COGEMA, Velizy-Villacoublay (France); Accominotti, M. [Hopital Edouard Heriot, Lyon (France)] [Hopital Edouard Heriot, Lyon (France); Domard, A. [Universite Claude Bernard, Villeurbanne (France)] [Universite Claude Bernard, Villeurbanne (France)

1997-03-19

242

Relation between soil physical parameters and modulus of subgrade reaction and application in soil structure interaction  

Microsoft Academic Search

Foundations are engineering structures, which transfer its own weight and the load from superstructure to the underlying soil. Loading causes stress increases in soil mass. Shear strength of the soil depends on the shear strength parameters (c,?) of soil and these two parameters can be obtained with various laboratory and in situ tests. In this study, shear strength parameters and

Zeki Karaca; Azer A. Kasimzade; Mehtap Ak

243

Hydrophobic folding units derived from dissimilar monomer structures and their interactions.  

PubMed Central

We have designed an automated procedure to cut a protein into compact hydrophobic folding units. The hydrophobic units are large enough to contain tertiary non-local interactions, reflecting potential nucleation sites during protein folding. The quality of a hydrophobic folding unit is evaluated by four criteria. The first two correspond to visual characterization of a structural domain, namely, compactness and extent of isolation. We use the definition of Zehfus and Rose (Zehfus MH, Rose GD, 1986, Biochemistry 25:35-340) to calculate the compactness of a cut protein unit. The isolation of a unit is based on the solvent accessible surface area (ASA) originally buried in the interior and exposed to the solvent after cutting. The third quantity is the hydrophobicity, equivalent to the fraction of the buried non-polar ASA with respect to the total non-polar ASA. The last criterion in the evaluation of a folding unit is the number of segments it includes. To conform with the rationale of obtaining hydrophobic units, which may relate to early folding events, the hydrophobic interactions are implicitly and explicitly applied in their generation and assessment. We follow Holm and Sander (Holm L, Sander C, 1994, Proteins 19:256-268) to reduce the multiple cutting-point problem to a one-dimensional search for all reasonable trial cuts. However, as here we focus on the hydrophobic cores, the contact matrix used to obtain the first non-trivial eigenvector contains only hydrophobic contracts, rather than all, hydrophobic and hydrophilic, interactions. This dataset of hydrophobic folding units, derived from structurally dissimilar single chain monomers, is particularly useful for investigations of the mechanism of protein folding. For cases where there are kinetic data, the one or more hydrophobic folding units generated for a protein correlate with the two or with the three-state folding process observed. We carry out extensive amino acid sequence order independent structural comparisons to generate a structurally non-redundant set of hydrophobic folding units for fold recognition and for statistical purposes. PMID:9007974

Tsai, C. J.; Nussinov, R.

1997-01-01

244

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, Jörg; Andrä, Jörg; Rössle, Manfred; Richter, Walter; Silva, Ana Paula Galvão da; Krensky, Alan M.; Clayberger, Carol; Brandenburg, Klaus

2009-01-01

245

Mesoscopic effective material parameters for thin layers modeled as single and double grids of interacting loaded wires  

Microsoft Academic Search

As an example of thin composite layers we consider single and double grids of periodically arranged interacting wires loaded with a certain distributed reactive impedance. Currents induced to the wires by a normally incident plane wave are calculated analytically and the corresponding dipole moment densities are determined. Using this data and calculated averaged fields we assign mesoscopic material parameters for

Pekka Ikonen; Elena Saenz; Ramon Gonzalo; Constantin Simovski; Sergei Tretyakov

2007-01-01

246

Effect of hydrophobic interactions on volume and thermal expansivity as derived from micelle formation.  

PubMed

Volumetric parameters have long been used to elucidate the phenomena governing the stability of protein structures, ligand binding, or transitions in macromolecular or colloidal systems. In spite of much success, many problems remain controversial. For example, hydrophobic groups have been discussed to condense adjacent water to a volume lower than that of bulk water, causing a negative contribution to the volume change of unfolding. However, expansivity data were interpreted in terms of a structure-making effect that expands the water interacting with the solute. We have studied volume and expansivity effects of transfer of alkyl chains into micelles by pressure perturbation calorimetry and isothermal titration calorimetry. For a series of alkyl maltosides and glucosides, the methylene group contribution to expansivity was obtained as 5 uL/(mol K) in a micelle (mimicking bulk hydrocarbon) but 27 uL/(mol K) in water (20 °C). The latter value is virtually independent of temperature and similar to that obtained from hydrophobic amino acids. Methylene contributions of micellization are about -60 J/(mol K) to heat capacity and 2.7 mL/mol to volume. Our data oppose the widely accepted assumption that water-exposed hydrophobic groups yield a negative contribution to expansivity at low temperature that would imply a structure-making, water-expanding effect. PMID:22950856

Nazari, Mozhgan; Fan, Helen Y; Heerklotz, Heiko

2012-10-01

247

Neutral winds derived from IRI parameters and from the HWM87 wind model for the SUNDIAL campaign of September, 1986  

Microsoft Academic Search

Meridional neutral winds derived from the height of the maximum ionization of the F2-layer are compared with values from results of the HWM87 empirical neutral wind model. The time period considered in this study is the SUNDIAL-2 campaign, September 21 through October 5, 1986. Winds have been derived from measurements by a global network of ionosondes, as well as from

K. L. Miller; A. E. Hedin; P. J. Wilkinson; D. G. Torr; P. G. Richards

1990-01-01

248

Neutral winds derived from IRI parameters and from the HWM87 wind model for the sundial campaign of September, 1986  

Microsoft Academic Search

Meridional neutral winds derived from the height of the maximum ionization of the F2 layer are compared with values from results of the HWM87 empirical neutral wind model. The time period considered is the SUNDIAL-2 campaign, 21 Sept. through 5 Oct. 1986. Winds were derived from measurements by a global network of ionosondes, as well as from similar quantities generated

K. L. Miller; A. E. Hedin; P. J. Wilkinson; D. G. Torr; P. G. Richards

1990-01-01

249

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

250

A SNAP-Tagged Derivative of HIV1—A Versatile Tool to Study Virus-Cell Interactions  

Microsoft Academic Search

Fluorescently labeled human immunodeficiency virus (HIV) derivatives, combined with the use of advanced fluorescence microscopy techniques, allow the direct visualization of dynamic events and individual steps in the viral life cycle. HIV proteins tagged with fluorescent proteins (FPs) have been successfully used for live-cell imaging analyses of HIV-cell interactions. However, FPs display limitations with respect to their physicochemical properties, and

Manon Eckhardt; Maria Anders; Walter Muranyi; Mike Heilemann; Jacomine Krijnse-Locker; Barbara Müller

2011-01-01

251

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

252

Interactions between tenofovir and nevirapine in CD4+ T cells and monocyte-derived macrophages restrict their intracellular accumulation  

PubMed Central

Objectives There is no pharmacokinetic interaction between tenofovir and nevirapine, but a higher emergence rate of resistance mutations has been reported when these drugs are coadministered. We sought to examine if there is a potential intracellular interaction that may account for the emergence of resistant virus. Methods Primary CD4+ and CD14+ cells were isolated from healthy volunteer blood. Monocyte-derived macrophages were differentiated from CD14+ cells. Accumulation of radiolabelled tenofovir and nevirapine was then assessed in these cells. Results We show here that tenofovir and nevirapine immune cell intracellular concentrations are lower when coincubated in CD4+ cells and monocyte-derived macrophages, but not in CD14+ cells. Conclusions These data indicate a potential intracellular drug–drug interaction between these drugs that warrants further investigation. PMID:23794601

Liptrott, N. J.; Curley, P.; Moss, D.; Back, D. J.; Khoo, S. H.; Owen, A.

2013-01-01

253

Identifying the Cognitive Needs of Visitors and Content Selection Parameters for Designing the Interactive Kiosk  

E-print Network

Identifying the Cognitive Needs of Visitors and Content Selection Parameters for Designing of visitors. Our objective is to identify the cognitive needs of museum visitors and the content selection, Cognitive needs, Content selection parameters, Visitor / user experience 1 Introduction This research

Paris-Sud XI, Université de

254

A lumped parameter model for acarine predator–prey population interactions  

Microsoft Academic Search

We hereby describe a modelling strategy, based on the implementation of composite models for the numerical simulation of the predator–prey local dynamics. We define a lumped parameter model for the dynamics of the system, where the abundance of the populations are given in terms of their biomass. The model is characterised by bio-ecological parameters (maximum specific rates and conversion factors)

G Buffoni; G Gilioli

2003-01-01

255

The Bombyx ovary-derived cell line endogenously expresses PIWI/PIWI-interacting RNA complexes  

PubMed Central

Genetic studies and large-scale sequencing experiments have revealed that the PIWI subfamily proteins and PIWI-interacting RNAs (piRNAs) play an important role in germ line development and transposon control. Biochemical studies in vitro have greatly contributed to the understanding of small interfering RNA (siRNA) and microRNA (miRNA) pathways. However, in vitro analyses of the piRNA pathway have been thus far quite challenging, because their expression is largely restricted to the germ line. Here we report that Bombyx mori ovary-derived cultured cell line, BmN4, endogenously expresses two PIWI subfamily proteins, silkworm Piwi (Siwi) and Ago3 (BmAgo3), and piRNAs associated with them. Siwi-bound piRNAs have a strong bias for uridine at their 5? end and BmAgo3-bound piRNAs are enriched for adenine at position 10. In addition, Siwi preferentially binds antisense piRNAs, whereas BmAgo3 binds sense piRNAs. Moreover, we identified many pairs in which Siwi-bound antisense and BmAgo3-bound sense piRNAs are overlapped by precisely 10 nt at their 5? ends. These signatures are known to be important for secondary piRNA biogenesis in other organisms. Taken together, BmN4 is a unique cell line in which both primary and secondary steps of piRNA biogenesis pathways are active. This cell line would provide useful tools for analysis of piRNA biogenesis and function. PMID:19460866

Kawaoka, Shinpei; Hayashi, Nobumitsu; Suzuki, Yutaka; Abe, Hiroaki; Sugano, Sumio; Tomari, Yukihide; Shimada, Toru; Katsuma, Susumu

2009-01-01

256

The Bombyx ovary-derived cell line endogenously expresses PIWI/PIWI-interacting RNA complexes.  

PubMed

Genetic studies and large-scale sequencing experiments have revealed that the PIWI subfamily proteins and PIWI-interacting RNAs (piRNAs) play an important role in germ line development and transposon control. Biochemical studies in vitro have greatly contributed to the understanding of small interfering RNA (siRNA) and microRNA (miRNA) pathways. However, in vitro analyses of the piRNA pathway have been thus far quite challenging, because their expression is largely restricted to the germ line. Here we report that Bombyx mori ovary-derived cultured cell line, BmN4, endogenously expresses two PIWI subfamily proteins, silkworm Piwi (Siwi) and Ago3 (BmAgo3), and piRNAs associated with them. Siwi-bound piRNAs have a strong bias for uridine at their 5' end and BmAgo3-bound piRNAs are enriched for adenine at position 10. In addition, Siwi preferentially binds antisense piRNAs, whereas BmAgo3 binds sense piRNAs. Moreover, we identified many pairs in which Siwi-bound antisense and BmAgo3-bound sense piRNAs are overlapped by precisely 10 nt at their 5' ends. These signatures are known to be important for secondary piRNA biogenesis in other organisms. Taken together, BmN4 is a unique cell line in which both primary and secondary steps of piRNA biogenesis pathways are active. This cell line would provide useful tools for analysis of piRNA biogenesis and function. PMID:19460866

Kawaoka, Shinpei; Hayashi, Nobumitsu; Suzuki, Yutaka; Abe, Hiroaki; Sugano, Sumio; Tomari, Yukihide; Shimada, Toru; Katsuma, Susumu

2009-07-01

257

The effects of isoflurane anaesthesia on some Doppler-derived cardiac parameters in the common buzzard ( Buteo buteo)  

Microsoft Academic Search

In order to gain an initial overview of the influence of anaesthesia on the results of Doppler-derived blood flow measurements in raptors, the heart rate as well as three different sample volumes of pulsed-wave spectral Doppler-derived flow velocity (diastolic flow across the left and right atrioventricular valve, systolic flow across the aortic valve) were determined in 10 common buzzards (Buteo

Jens Straub; Neil A. Forbes; Jens Thielebein; Michael Pees; Maria-E. Krautwald-Junghanns

2003-01-01

258

Dielectric Parameters and Hydrogen Bond Interaction Study of Binary Alcohol Mixtures  

Microsoft Academic Search

The formation of hydrogen bonds between different types of molecules in binary alcohol mixtures (methyl alcohol, ethyl alcohol,\\u000a ethylene glycol, propylene glycol and glycerol) have been investigated (each system at 21 mixture concentrations) by an analysis\\u000a of their dielectric parameters. The static dielectric constant ?\\u000a o, limiting high-frequency dielectric constant ?\\u000a ?, excess dielectric parameters ?\\u000a oE and ?\\u000a ?E,

R. J. Sengwa; Sonu Sankhla; N. Shinyashiki

2008-01-01

259

An interactive fuzzy satisficing method for multiobjective block angular linear programming problems with fuzzy parameters  

Microsoft Academic Search

In this paper, by considering the experts’ imprecise or fuzzy understanding of the nature of the parameters in the problem-formulation process, large-scale multiobjective block-angular linear programming problems involving fuzzy parameters characterized by fuzzy numbers are formulated. Using the ?-level sets of fuzzy numbers, the corresponding nonfuzzy ?-programming problem is introduced. The fuzzy goals of the decision maker for the objective

Masatoshi Sakawa; Kosuke Kato

2000-01-01

260

Coarse-Grain Simulations of Skin Ceramide NS with Newly Derived Parameters Clarify Structure of Melted Phase.  

PubMed

Ceramides are lipids that are involved in numerous biologically important structures (e.g., the stratum corneum and ceramide-rich platforms) and processes (e.g., signal transduction and membrane fusion), but their behavior is not fully understood. We report coarse-grain force field parameters for N-lignocerylsphingosine (ceramide NS, also known as ceramide 2) that are consistent with the Martini force field. These parameters were optimized for simulations in the gel phase and validated against atomistic simulations. Coarse-grained simulations with our parameters provide areas per lipid, membrane thicknesses, and electron density profiles that are in good agreement with atomistic simulations. Properties of the simulated membranes are compared with available experimental data. The obtained parameters were used to model the phase behavior of ceramide NS as a function of temperature and hydration. At low water content and above the main phase transition temperature, the bilayer melts into an irregular phase, which may correspond to the unstructured melted-chain phase observed in X-ray diffraction experiments. The developed parameters also reproduce the extended conformation of ceramide, which may occur in the stratum corneum. The parameters presented herein will facilitate studies on important complex functional structures such as the uppermost layer of the skin and ceramide-rich platforms in phospholipid membranes. PMID:25679231

Sovová, Žofie; Berka, Karel; Otyepka, Michal; Jure?ka, Petr

2015-03-12

261

Experimental Studies of Propellant Loading Parameters and Plasma Flow-Field Interactions  

Microsoft Academic Search

Propellant-plasma interaction has been attracting great interests among most researchers for application to an electrothermal-chemical (ETC) gun. Previous works have shown that propellant-plasma interaction can enhance burning rates due to increased surface erosion of propellants compared to that of conventional ignition. Plasma radiation and heat convection are the dominant mechanism of energy transfer based on both experimental data and numerical

Zhenggang Xiao; Aowei Xue; Sanjiu Ying; Weidong He; Fuming Xu; Baoguo Hou

2008-01-01

262

Experimental Studies of Propellant Loading Parameters and Plasma Flow-Field Interactions  

Microsoft Academic Search

Propellant-plasma interaction has been attracting great interests among most researchers for application to an electrothermal-chemical (ETC) gun. Previous works have shown that propellant-plasma interaction can enhance burning rates due to increased surface erosion of propellants as compared to that of conventional ignition. Plasma radiation and heat convection are the dominant mechanism of energy transfer based on both experimental data and

Zhenggang Xiao; Aowei Xue; Sanjiu Ying; Weidong He; Fuming Xu; Baoguo Hou

2009-01-01

263

Thermodynamic parameters of the interaction of Urtica dioica agglutinin with N-acetylglucosamine and its oligomers  

Microsoft Academic Search

The interaction between Urtica dioica agglutinin (UDA) and N-acetylglucosamine (GlcNAc) and its ß(1-4)-linked oligomers was studied by fluorescence titration and isothermal titration microcalorimetry. UDA possesses one significant binding site that can be measured calorimetrically. This site is composed of three subsites, each subsite accommodating one GlcNAc residue. The interaction is enthalpically driven, and the binding area of UDA is characterized

Reiko T. Lee; Hans-Joachim Gabius; Yuan C. Lee

1998-01-01

264

Orbital parameters of binary radio pulsars in globular clusters and stellar interactions  

E-print Network

The observed distribution of globular cluster binary radio pulsars in the eccentricity versus orbital period plane can be explained as a result of binary-single star interactions. Our numerical and analytical study hints that the highest eccentricity binaries in clusters are likely to be from exchange and/or merger of a single star with a binary component, while the intermediate eccentricity systems are probably results of fly-by interactions.

Bagchi, Manjari

2009-01-01

265

Interactions between glycine derivatives and mineral surfaces: Implications for the origins of life on planetary surfaces  

NASA Astrophysics Data System (ADS)

Various mechanisms could have delivered amino acids to the prebiotic Earth (Miller and Orgel 1974). The polymerization of amino acids may have been important for the origin of life, as peptides may have been components for the first self-replicating systems (Kauffman 1971; Yao et al 1998). Though amino acid concentrations in the primitive oceans were likely too dilute for significant oligomerization to occur (Cleaves et al 2009), mineral surface adsorption may have concentrated these biomolecules (Bernal 1951; Lambert 2008). Few studies have examined the catalytic effects of mineral surfaces on aqueous peptide oligomerization or degradation. As unactivated amino acid polymerization is thermodynamically unfavorable and kinetically slow in aqueous solution, we studied the reverse reaction of polymer degradation to measure potential mineral catalysis. Glycine (G) derivatives glycylglycine (GG), diketopiperazine (DKP), and glycylglycylglycine (GGG) were reacted with different minerals (calcite, hematite, montmorillonite, rutile, amorphous silica, and pyrite) in the presence of 0.05 M pH 8.1 KHCO3 buffer and 0.1 M NaCl as background electrolyte. Experiments were performed by reacting the aqueous amino acid derivative-mineral mixtures in a thermostatted oven (modified to accommodate a mechanical rotator) at 25°, 50° or 70°C. Samples were removed after 30, 60, 90, and 140 hours. Samples were then analyzed using high performance liquid chromatography to quantify the products. Besides mineral catalysis, it was determined that degradation of GGG proceeds principally via a GGG ? DKP + G mechanism, rather than via GGG ? GG + G. Below 70°C kinetics were generally too sluggish to detect catalytic activity over reasonable laboratory time-scales at this pH. At 70°C, pyrite was the only mineral with detectible catalytic effects on the degradation of GGG. GGG degraded ~ 1.5 - 4 x faster in the presence of pyrite than in control reactions, depending on the ratio of solution to mineral surface area. Catalysis was found to be saturable, suggesting the presence of discrete catalytic sites on the mineral surface. These and other results will be presented and discussed. References Bernal, J. D. (1951) The Physical Basis of Life (Routledge, London). Cleaves, H.J., Aubrey, A.D., Bada, J.L. (2009) An evaluation of the critical parameters for abiotic peptide synthesis in submarine hydrothermal systems. Origins of Life Evol Biosph. 39:109-26. Kauffman, S.A. (1971) Cellular homeostasis, epigenesis and replication in randomly aggregated macromolecular systems. Cybernetics and Systems: An International Journal 1: 71 - 96. Lambert, J. (2008) Adsorption and polymerization of amino acids on mineral surfaces: A review. Origins of Life Evol. Biosph. 38: 211-42. Miller, S.L. and Orgel, L.E. (1974) The Origins of Life on the Earth, Prentice Hall (Englewood Cliffs, NJ) Yao, Y., Ghosh, I., Zutshi, R., Chmielewski, J. (1998) Selective amplification by auto- and cross-catalysis in a replicating peptide system. Nature 396, 447 - 450.

Marshall-Bowman, K. J.; Cleaves, H. J.; Sverjensky, D. A.; Hazen, R. M.

2009-12-01

266

Simulations of Anionic Lipid Membranes: Development of Interaction-Specific Ion Parameters and Validation using NMR Data  

PubMed Central

Overbinding of ions to lipid head groups is a potentially serious artifact in simulations of charged lipid bilayers. In this study, the Lennard-Jones radii in the CHARMM force field for interactions of Na+ and lipid oxygen atoms of carboxyl, phosphate and ester groups were revised to match osmotic pressure data on sodium acetate, and electrophoresis data on palmitoyloleoyl phosphatidylcholine (POPC) vesicles. The new parameters were then validated by successfully reproducing previously published experimental NMR deuterium order parameters for dimyristoyl phosphatidylglycerol (DMPG) and newly obtained values for palmitoyloleoyl phosphatidylserine (POPS). Although the increases in Lennard-Jones diameters are only 0.02 to 0.12 Å, they are sufficient to reduce Na+ binding, and thereby increase surface areas per lipid by 5–10% compared with the unmodified parameters. PMID:23924441

Venable, Richard M.; Luo, Yun; Gawrisch, Klaus; Roux, Benoît; Pastor, Richard W.

2013-01-01

267

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

268

Siladenoserinols A-L: new sulfonated serinol derivatives from a tunicate as inhibitors of p53-Hdm2 interaction.  

PubMed

Siladenoserinols A-L were isolated from a tunicate as inhibitors of p53-Hdm2 interaction, a promising target for cancer chemotherapy. Their structures including the absolute configurations were elucidated to be new sulfonated serinol derivatives, each of which contains a 6,8-dioxabicyclo[3.2.1]octane unit and either glycerophosphocholine or glycerophosphoethanolamine moiety. They inhibited p53-Hdm2 interaction with IC(50) values of 2.0-55 ?M. Among them, siladenoserinol A and B exhibited the strongest inhibition with an IC(50) value of 2.0 ?M. PMID:23268733

Nakamura, Yuichi; Kato, Hikaru; Nishikawa, Tadateru; Iwasaki, Noriyuki; Suwa, Yoshiaki; Rotinsulu, Henki; Losung, Fije; Maarisit, Wilmar; Mangindaan, Remy E P; Morioka, Hiroshi; Yokosawa, Hideyoshi; Tsukamoto, Sachiko

2013-01-18

269

BandGap Bowing Parameter of the InxGa1-xN Derived From Theoretical Simulation  

Microsoft Academic Search

The band-gap energy and band-gap bowing parameter of the wurtzite InGaN alloys are investigated numerically with the CASTEP simulation program. The simulation results suggest that the unstrained band-gap bowing parameter for the wurtzite InGaN alloys is b=1.21± 0.03 eV@. The simulation results also show that the width of the InxGa1-xN top valence band at the Gamma point decreases when the

Yen-Kuang Kuo; Wen-Wei Lin; Jiann Lin

2001-01-01

270

Redox and complexation interactions of neptunium(V) with quinonoid-enriched humic derivatives  

SciTech Connect

Actinides in their higher valence states (e.g., MO{sub 2}{sup +} and MO{sub 2}{sup 2+}, where M can be Np, Pu, etc) possess a higher potential for migration and in turn pose a substantial environmental threat. To minimize this potential for migration, reducing them to lower oxidation states (e.g., their tetravalent state) can be an attractive and efficient remedial process. These lower oxidation states are often much less soluble in natural aqueous media and are, therefore, less mobile in the environment. The research presented here focuses on assessing the performance of quinonoid-enriched humic derivatives with regards to complexing and/or reducing Np(V) present in solution. These 'designer' humics are essentially derived reducing agents that can serve as reactive components of a novel humic-based remediation technology. The derivatives are obtained by incorporating different quinonoid-moieties into leonardite humic acids. Five quinonoid-derivatives are tested in this work and all five prove more effective as reducing agents for selected actinides than the parent leonardite humic acid, and the hydroquinone derivatives are better than the catechol derivatives. The reduction kinetics and the Np(V) species formed with the different derivatives are studied via a batch mode using near-infrared (NIR)-spectroscopy. Np(V) reduction by the humic derivatives under anoxic conditions at 293 K and at pH 4.7 obeys first-order kinetics. Rate constants range from 1.70 x 10{sup -6} (parent humic acid) to 1.06 x 10{sup -5} sec{sup -1} (derivative with maximum hydroquinone content). Stability constants for Np(V)-humic complexes calculated from spectroscopic data produce corresponding Log{beta} values of 2.3 for parent humic acid and values ranging from 2.5 to 3.2 at pH 4.7 and from 3.3 to 3.7 at pH 7.4 for humic derivatives. Maximum constants are observed for hydroquinone-enriched derivatives. It is concluded that among the humic derivatives tested, the hydroquinone-enriched ones are the most useful for addressing remedial needs of actinide-contaminated aquifers.

Shcherbina, Natalia S. [Vernadsky Inst. of Geochemistry and Analytical Chemistry, Moscow, Russia; Perminova, Irina V. [Lomonosov Moscow State University, Moscow, Russia; Kalmykov, Stephan N. [Lomonosov Moscow State University, Moscow, Russia; Kovalenko, Anton N. [Lomonosov Moscow State University, Moscow, Russia; Novikov, Alexander P. [Vernadsky Inst. of Geochemistry and Analytical Chemistry, Moscow, Russia; Haire, Richard {Dick} G [ORNL

2007-01-01

271

Establishing dependences between different lipophilic parameters of new potentially biologically active N-substituted-2-phenylacetamide derivatives by applying multivariate methods.  

PubMed

Lipophilicity, a very important parameter in the potential biological activities of molecules, was investigated for newly synthesized N-substituted-2-phenylacetamide derivatives. The determination was carried out in two ways: first experimentally, by applying thin-layer chromatography (TLC) on reversed-phase TLC (RPTLC) RP18F254s in the presence of one protic (methanol) and one aprotic solvent (acetonitrile) and then mathematically, by using different software packages. The intercept of the linear dependence between volume fractions of the organic solvent and the retention parameters obtained by TLC is known as the retention chromatographic constant, R(M)(0), while the slope represents the m value. In order to establish the dependences between the partition coefficient, log P as the standard measure of lipophilicity and the alternative lipophilic parameters obtained experimentally by TLC, R(M)(0) and m values, linear regression analysis and multivariate methods, cluster analysis (CA) and principal component analysis (PCA), were used. All applied methods gave approximately similar results. Although there is a linear dependence between the two chromatographic parameters, the retention constant, R(M)(0), and the m values, only R(M)(0) shows suitable similarity with the standard measure of lipophilicity of the investigated N-substituted-2-phenylacetamide derivatives at the given conditions. The existence of this resemblance proves that the chromatographic retention constant, R(M)(0), obtained by RPTLC could be successfully used for the description of lipophilicity of investigated compounds. On the other hand, the results confirmed that the applied linear regression analysis and the multivariate analysis (CA and PCA) have the ability to compare lipophilic parameters of the investigated phenylacetamide derivatives obtained in different ways. PMID:24981978

Vastag, Gyöngyi; Apostolov, Suzana; Matijevi?, Borko; Petrovi?, Slobodan

2015-02-01

272

THE USE OF OPERATIONAL ASSIMILATED SURFACE PARAMETERS OF THE ALPS DERIVED FROM NOAA AVHRR DATA FOR NWP  

Microsoft Academic Search

The assimilation of operational retrieved surface parameters from satellite data can be of great value for numerical weather prediction models. This fact becomes even more important for the heterogeneous European Alps and for the assimilation process of the newest NWP's with grid sizes of a few square kilometers. On the one hand, the data provided by the existing numerous meteorological

D. Oesch; M. D. Müller; A. Hauser; N. Foppa; S. Wunderle

273

Relationship between sounding derived parameters and the strength of tornadoes in Europe and the USA from reanalysis data  

Microsoft Academic Search

Proximity soundings from reanalysis data for tornado events in Europe for the years 1958 to 1999 and in the US for the years 1991 to 1999 have been used for generating distributions of parameter combinations important for severe convection. They include parcel updraft velocity (WMAX) and deep-layer shear (DLS), lifting condensation level (LCL) and deep-layer shear (DLS), and LCL and

S. Grünwald; H. E. Brooks

2011-01-01

274

Productivity, Respiration, and Light-Response Parameters of World Grassland and Agroecosystems Derived From Flux-Tower Measurements  

Technology Transfer Automated Retrieval System (TEKTRAN)

Grasslands and agroecosystems occupy one-third of the terrestrial area, but their contribution to the global carbon cycle remains uncertain. We used a set of 316 site-years of CO2 exchange measurements to quantify gross primary productivity, respiration, and light-response parameters of grasslands, ...

275

Matrix–filler interactions in polysilazane-derived ceramics with Al 2O 3 and ZrO 2 fillers  

Microsoft Academic Search

Interactions between a poly(vinyl)silazane and Al2O3 or Y2O3-stabilised ZrO2 fillers were studied during the fabrication of polysilazane-derived bulk ceramics in order to investigate the influence of oxide fillers on resulting properties. Specimens were produced by coating of the filler powders with the polysilazane, warm-pressing of the resulting composite powders, and pyrolytic conversion in flowing N2 at various temperatures between 1000°C

Thomas Konegger; Robert Potzmann; Michael Puchberger; Antje Liersch

2011-01-01

276

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. PMID:25325054

Brito, Paula M.; Antunes, Fernando

2014-01-01

277

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

278

Derivation of transfer parameters for use within the ERICA Tool and the default concentration ratios for terrestrial biota.  

PubMed

An ability to predict radionuclide activity concentrations in biota is a requirement of any method assessing the exposure of biota to ionising radiation. Within the ERICA Tool fresh weight whole-body activity concentrations in organisms are estimated using concentration ratios (the ratio of the activity concentration in the organism to the activity concentration in an environmental media). This paper describes the methodology used to derive the default terrestrial ecosystem concentration ratio database available within the ERICA Tool and provides details of the provenance of each value for terrestrial reference organisms. As the ERICA Tool considers 13 terrestrial reference organisms and the radioisotopes of 31 elements, a total of 403 concentration ratios were required for terrestrial reference organisms. Of these, 129 could be derived from literature review. The approaches taken for selecting the remaining values are described. These included, for example, assuming values for similar reference organisms and/or biogeochemically similar elements, and various simple modelling approaches. PMID:18406022

Beresford, N A; Barnett, C L; Howard, B J; Scott, W A; Brown, J E; Copplestone, D

2008-09-01

279

Neutral winds derived from IRI parameters and from the HWM87 wind model for the sundial campaign of September, 1986  

NASA Technical Reports Server (NTRS)

Meridional neutral winds derived from the height of the maximum ionization of the F2 layer are compared with values from results of the HWM87 empirical neutral wind model. The time period considered is the SUNDIAL-2 campaign, 21 Sept. through 5 Oct. 1986. Winds were derived from measurements by a global network of ionosondes, as well as from similar quantities generated by the International Reference Ionosphere. Global wind patterns from the three sources are similar. Differences tend to be the result of local or transient phenomena that are either too rapid to be described by the order of harmonics of the empirical models, or are the result of temporal changes not reproduced by models based on average conditions.

Miller, K. L.; Hedin, A. E.; Wilkinson, P. J.; Torr, D. G.; Richards, P. G.

1990-01-01

280

Neutral winds derived from IRI parameters and from the HWM87 wind model for the SUNDIAL campaign of September, 1986  

NASA Technical Reports Server (NTRS)

Meridional neutral winds derived from the height of the maximum ionization of the F2-layer are compared with values from results of the HWM87 empirical neutral wind model. The time period considered in this study is the SUNDIAL-2 campaign, September 21 through October 5, 1986. Winds have been derived from measurements by a global network of ionosondes, as well as from similar quantities generated by the International Reference Ionosphere. Global wind patterns from the three sources are similar. Differences tend to be the result of local or transient phenomena that are either too rapid to be described by the order of harmonics of the empirical models, or are the result of temporal changes not reproduced by models based on average conditions.

Miller, K. L.; Hedin, A. E.; Wilkinson, P. J.; Torr, D. G.; Richards, P. G.

1990-01-01

281

MODEL ROBUSTNESS VERSUS PARAMETER EVOLUTION: ASSORTATIVE INTERACTION WITHIN A BARGAINING GAME  

E-print Network

"Evolution of the Social Contract," Skyrms explores the use of evolutionary game theory to explain our, assortative interaction, social networks, evolutionary game theory, agent-based models. INTRODUCTION One explanations for human social behavior when theories relying on rational deliberation are lacking. His initial

Goadrich, Mark

282

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

283

Gravitational and higher-derivative interactions of a massive spin 5/2 field in (A)dS space  

SciTech Connect

Using an on shell gauge invariant formulation of relativistic dynamics I study the interaction vertices for a massive spin 5/2 Dirac field propagating in (anti-)de Sitter [(A)dS] space of dimension greater than or equal to four. The gravitational interaction vertex for the massive spin 5/2 field and all cubic vertices for the massive spin 5/2 field and massless spin 2 field with two and three derivatives are obtained. In dimension greater than four, I demonstrate that the gravitational vertex of the massive spin 5/2 field involves, in addition to the standard minimal gravitational vertex, contributions with two and three derivatives. I find that for the massive spin 5/2 and massless spin 2 fields one can build two higher-derivative vertices with two and three derivatives. Limits of massless and partial massless spin 5/2 fields in (A)dS space and limits of massive and massless spin 5/2 fields in flat space are discussed.

Metsaev, R. R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute, Leninsky Prospect 53, Moscow 119991 (Russian Federation)

2008-01-15

284

Gravitational and higher-derivative interactions of massive spin 5/2 field in (A)dS space  

E-print Network

Using on-shell gauge invariant formulation of relativistic dynamics we study interaction vertices for a massive spin 5/2 Dirac field propagating in (A)dS space of dimension greater than or equal to four. Gravitational interaction vertex for the massive spin 5/2 field and all cubic vertices for the massive spin 5/2 field and massless spin 2 field with two and three derivatives are obtained. In dimension greater that four, we demonstrate that the gravitational vertex of the massive spin 5/2 field involves, in addition to the standard minimal gravitational vertex, contributions with two and three derivatives. We find that for the massive spin 5/2 and massless spin 2 fields one can build two higher-derivative vertices with two and three derivatives. Limits of massless and partial massless spin 5/2 fields in (A)dS space and limits of massive and massless spin 5/2 fields in flat space are discussed.

R. R. Metsaev

2007-09-10

285

Mathematical model relating uniaxial compressive behavior of manufactured sand mortar to MIP-derived pore structure parameters.  

PubMed

The uniaxial compression response of manufactured sand mortars proportioned using different water-cement ratio and sand-cement ratio is examined. Pore structure parameters such as porosity, threshold diameter, mean diameter, and total amounts of macropores, as well as shape and size of micropores are quantified by using mercury intrusion porosimetry (MIP) technique. Test results indicate that strains at peak stress and compressive strength decreased with the increasing sand-cement ratio due to insufficient binders to wrap up entire sand. A compression stress-strain model of normal concrete extending to predict the stress-strain relationships of manufactured sand mortar is verified and agreed well with experimental data. Furthermore, the stress-strain model constant is found to be influenced by threshold diameter, mean diameter, shape, and size of micropores. A mathematical model relating stress-strain model constants to the relevant pore structure parameters of manufactured sand mortar is developed. PMID:25133257

Tian, Zhenghong; Bu, Jingwu

2014-01-01

286

A study of hydrogen bond of imidazole and its 4-nitro derivative by ab initio and DFT calculated NQR parameters  

Microsoft Academic Search

Nuclear quadrupole resonance (NQR) parameters of 14N, 2H of N2H groups are calculated for imidazole and 4-nitroimidazole using HF and B3LYP methods. These computations are performed on the basis of X-ray and neutron diffraction structural data which are collected at 100, 103, 123 and 293 K temperatures. In order to take into account intermolecular hydrogen bonds and the van der

S. K. Amini; N. L. Hadipour; F. Elmi

2004-01-01

287

Design, synthesis, and physico-chemical interactions of bile acid derived dimeric phospholipid amphiphiles with model membranes.  

PubMed

Understanding of amphiphile-membrane interactions is crucial in design and development of novel amphiphiles for drug delivery, gene therapy, and biomedical applications. Structure and physico-chemical properties of amphiphiles determine their interactions with biomembranes thereby influencing their drug delivery efficacies. Here, we unravel the interactions of bile acid derived dimeric phospholipid amphiphiles with model membranes using Laurdan-based hydration, DPH-based membrane fluidity, and differential scanning calorimetry studies. We synthesized three dimeric bile acid amphiphiles where lithocholic acid, deoxycholic acid, and cholic acid are conjugated to cholic acid phospholipid using click chemistry. Interactions of these dimeric amphiphiles with model membranes showed that these amphiphiles form different structural assemblies and molecular packing in model membranes depending on the number and position of free hydroxyl groups on bile acids. We discovered that cholic acid-cholic acid dimeric phospholipid form self-assembled aggregates in model membranes without changing membrane fluidity; whereas cholic acid-deoxycholic acid derived amphiphile induces membranes fluidity and hydration of model membranes. PMID:25746193

Kumar, Sandeep; Bhargava, Priyanshu; Sreekanth, Vedagopuram; Bajaj, Avinash

2015-06-15

288

Five-Parameter Grain Boundary Inclination Recovery with EBSD and Interaction Volume Models  

NASA Astrophysics Data System (ADS)

While electron backscatter diffraction (EBSD) patterns are often used to present two-dimensional information about a material microstructure, they are in fact a product of the three-dimensional electron interaction volume. Consequently, 3D spatial information exists in EBSD images, which is generally not accessed. Specifically, the inclination of the grain boundary plane may be observed in EBSD patterns taken near grain boundaries. If, at the same time, the shape of an electron interaction volume in the material is known, a grain boundary plane normal direction can be obtained from a sequence of EBSD images taken stepwise in a line crossing the grain boundary. Here, these two principles are used for demonstrating the determination of grain boundary normal vectors from EBSD images. Coherent twin boundaries and focused ion beam serial scan data are used for validation. Results indicate a mean error for this approach of 3 deg with a standard deviation of 3.8 deg.

Sorensen, Caroline; Basinger, John A.; Nowell, Matthew M.; Fullwood, David T.

2014-08-01

289

Protein conjugated with aldehydes derived from lipid peroxidation as an independent parameter of the carbonyl stress in the kidney damage  

PubMed Central

Background One of the well-defined and characterized protein modifications usually produced by oxidation is carbonylation, an irreversible non-enzymatic modification of proteins. However, carbonyl groups can be introduced into proteins by non-oxidative mechanisms. Reactive carbonyl compounds have been observed to have increased in patients with renal failure. In the present work we have described a procedure designed as aldehyde capture to calculate the protein carbonyl stress derived solely from lipid peroxidation. Methods Acrolein-albumin adduct was prepared as standard at alkaline pH. Rat liver microsomal membranes and serum samples from patients with diabetic nephropathy were subjected to the aldehyde capture procedure and aldol-protein formation. Before alkalinization and incubation, samples were precipitated and redisolved in 6M guanidine. The absorbances of the samples were read with a spectrophotometer at 266 nm against a blank of guanidine. Results Evidence showed abundance of unsaturated aldehydes derived from lipid peroxidation in rat liver microsomal membranes and in the serum of diabetic patients with advanced chronic kidney disease. Carbonyl protein and aldol-proteins resulted higher in the diabetic nephropathy patients (p < 0.004 and p < 0.0001 respectively). Conclusion The aldehyde-protein adduct represents a non oxidative component of carbonyl stress, independent of the direct amino acid oxidation and could constitute a practical and novelty strategy to measure the carbonyl stress derived solely from lipid peroxidation and particularly in diabetic nephropathy patients. In addition, we are in a position to propose an alternative explanation of why alkalinization of urine attenuates rhabdomyolysis-induced renal dysfunction. PMID:22059738

2011-01-01

290

Kinetic model framework for aerosol and cloud surface chemistry and gas-particle interactions: Part 1 - general equations, parameters, and terminology  

NASA Astrophysics Data System (ADS)

Aerosols and clouds play central roles in atmospheric chemistry and physics, climate, air pollution, and public health. The mechanistic understanding and predictability of aerosol and cloud properties, interactions, transformations, and effects are, however, still very limited. This is due not only to the limited availability of measurement data, but also to the limited applicability and compatibility of model formalisms used for the analysis, interpretation, and description of heterogeneous and multiphase processes. To support the investigation and elucidation of atmospheric aerosol and cloud surface chemistry and gas-particle interactions, we present a comprehensive kinetic model framework with consistent and unambiguous terminology and universally applicable rate equations and parameters. It allows to describe mass transport and chemical reactions at the gas-particle interface and to link aerosol and cloud surface processes with gas phase and particle bulk processes in systems with multiple chemical components and competing physicochemical processes. The key elements and essential aspects of the presented framework are: a simple and descriptive double-layer surface model (sorption layer and quasi-static layer); straightforward flux-based mass balance and rate equations; clear separation of mass transport and chemical reactions; well-defined rate parameters (uptake and accommodation coefficients, reaction and transport rate coefficients); clear distinction between gas phase, gas-surface, and surface-bulk transport (gas phase diffusion correction, surface and bulk accommodation); clear distinction between gas-surface, surface layer, and surface-bulk reactions (Langmuir-Hinshelwood and Eley-Rideal mechanisms); mechanistic description of concentration and time dependencies; flexible inclusion/omission of chemical species and physicochemical processes; flexible convolution/deconvolution of species and processes; and full compatibility with traditional resistor model formulations. Exemplary practical applications and model calculations illustrating the relevance of the above aspects will be presented in a companion paper (Ammann and Pöschl, 2005). We expect that the presented model framework will serve as a useful tool and basis for experimental and theoretical studies investigating and describing atmospheric aerosol and cloud surface chemistry and gas-particle interactions. In particular, it is meant to support the planning and design of laboratory experiments for the elucidation and determination of kinetic parameters; the establishment, evaluation, and quality assurance of comprehensive and self-consistent collections of rate parameters; and the development of detailed master mechanisms for process models and the derivation of simplified but yet realistic parameterizations for atmospheric and climate models.

Pöschl, U.; Rudich, Y.; Ammann, M.

2005-04-01

291

Derivation of Backpropagation When optimizing the parameters of a function to reduce error (or some other performance  

E-print Network

= (y b y) @ b y @w b y is computed by: b y = w 0 + X j w j g w 0;j + X k w k;j x k ! Let a j = g w the following partial derivatives for the output weights. @ b y @w 0 = 1 @ b y @w j = a j For the hidden unit: @ b y @w 0;j = @ b y @a j @a j @s j @s j @w 0;j = w j @g(s j ) @s j 1 = w j g 0 (s j ) 1 #12; @ b y @w

Bylander, Tom

292

Ab initio analysis of the tight-binding parameters and magnetic interactions in Na2IrO3  

NASA Astrophysics Data System (ADS)

By means of density functional theory (DFT) calculations [with and without inclusion of spin-orbit (SO) coupling] we present a detailed study of the electronic structure and corresponding microscopic Hamiltonian parameters of Na2IrO3. In particular, we address the following aspects: (i) We investigate the role of the various structural distortions and show that the electronic structure of Na2IrO3 is exceptionally sensitive to structural details. (ii) We discuss both limiting descriptions for Na2IrO3—quasimolecular orbitals (small SO limit, itinerant) versus relativistic orbitals (large SO limit, localized)—and show that the description of Na2IrO3 lies in an intermediate regime. (iii) We investigate whether the nearest neighbor Kitaev-Heisenberg model is sufficient to describe the electronic structure and magnetism in Na2IrO3. In particular, we verify the recent suggestion of an antiferromagnetic Kitaev interaction and show that it is not consistent with actual or even plausible electronic parameters. Finally, (iv) we discuss correlation effects in Na2IrO3. We conclude that while the Kitaev-Heisenberg Hamiltonian is the most general expression of the quadratic spin-spin interaction in the presence of spin-orbit coupling (neglecting single-site anisotropy), the itinerant character of the electrons in Na2IrO3 makes other terms beyond this model (including, but not limited to, 2nd and 3rd neighbor interactions) essential.

Foyevtsova, Kateryna; Jeschke, Harald O.; Mazin, I. I.; Khomskii, D. I.; Valentí, Roser

2013-07-01

293

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

294

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

295

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

296

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

297

Monte Carlo Simulation of Protein-Induced Lipid Demixing in a Membrane with Interactions Derived from Experiment  

PubMed Central

Lipid domain formation induced by annexin was investigated in mixtures of phosphatidylcholine (PC), phosphatidylserine (PS), and cholesterol (Chol), which were selected to mimic the inner leaflet of a eukaryotic plasma membrane. Annexins are ubiquitous and abundant cytoplasmic, peripheral proteins, which bind to membranes containing PS in the presence of calcium ions (Ca2+), but whose function is unknown. Prompted by indications of interplay between the presence of cholesterol in PS/PC mixtures and the binding of annexins, we used Monte Carlo simulations to investigate protein and lipid domain formation in these mixtures. The set of interaction parameters between lipids and proteins was assigned by matching experimental observables to corresponding variables in the calculations. In the case of monounsaturated phospholipids, the PS-PC and PC-Chol interactions are weakly repulsive. The interaction between protein and PS was determined based on experiments of annexin binding to PC/PS mixtures in the presence of Ca2+. Based on the proposal that PS and cholesterol form a complex in model membranes, a favorable PS-Chol interaction was postulated. Finally, protein-protein favorable interactions were also included, which are consistent with observations of large, two-dimensional, regular arrays of annexins on membranes. Those net interactions between pairs of lipids, proteins and lipids, and between proteins are all small, of the order of the average kinetic energy. We found that annexin a5 can induce formation of large PS domains, coincident with protein domains, but only if cholesterol is present. PMID:22004747

Almeida, Paulo F.; Best, Alexis; Hinderliter, Anne

2011-01-01

298

A study of photon interaction parameters in some commonly used solvents  

Microsoft Academic Search

Various parameters of dosimetric interest such as mass attenuation coefficients, effective atomic numbers and electron densities of some commonly used solvents such as acetonitrile (C4H3N), butanol (C4H9OH), chlorobenzene (C6H5Cl), diethylether (C4H10O), ethanol (C2H5OH), methanol (CH3OH), propanol (C3H7OH) and water (H2O) were computed in the wide energy range of 10 keV-100 GeV. A comparative study of two different methods used to

Tejbir Singh; Paramjeet Kaur; Parjit S. Singh

2007-01-01

299

Account of the Gravitational Interaction in an Estimate of the Parameters of Pinch Plasmoids  

NASA Astrophysics Data System (ADS)

Exact solutions of the Einstein-Maxwell equations in GTR for centrosymmetric dust and a free electromagnetic field are applied to a description of pinch plasmoids formed in experiments on the collapse of a charge-neutralized high-voltage discharge in a medium in which superhigh energy densities are reached, where an account of the curvature of spacetime becomes important. The given solutions are also used to estimate the parameters of cosmological objects - maximons, whose electric charge is equal to the "gravitational charge." These objects are identified with the throat - the extremal static hypersurface of the inner space of the plasmoid and maximon observed from the Reissner-Nordström vacuum.

Bogdanovich, B. Yu.; Nesterovich, A. V.; Sukhanova, L. A.; Khlestkov, Yu. A.

2015-02-01

300

Interaction water-polyethyleneglycols: Determination of hydration parameters from hydrodynamic data  

NASA Astrophysics Data System (ADS)

Densities, viscosities and refractive indexes of diluted aqueous solutions of polyethylene glycols (Mw=200-6000) are determined at 25 °C. The non-linear increase of viscosity B and C coefficients with the number of ethylenoxide (EO) units are discussed. The solvation (hydration) becomes dominant when the number of ethylenoxide group increases. The hydration parameter, ?, the specific increment of density, dds/dc, and of refractive index, dnD/dc, for the various PEGs are the consequence of dimension and of conformation that assumes the polymer.

Donato, Ines D.; Agozzino, Pasquale; Perzia, Patrizia

2000-04-01

301

Herb drug interaction: effect of Manix® 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

302

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

303

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

304

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

2014-11-25

305

Targeting diverse protein-protein interaction interfaces with ?/?-peptides derived from the Z-domain scaffold.  

PubMed

Peptide-based agents derived from well-defined scaffolds offer an alternative to antibodies for selective and high-affinity recognition of large and topologically complex protein surfaces. Here, we describe a strategy for designing oligomers containing both ?- and ?-amino acid residues ("?/?-peptides") that mimic several peptides derived from the three-helix bundle "Z-domain" scaffold. We show that ?/?-peptides derived from a Z-domain peptide targeting vascular endothelial growth factor (VEGF) can structurally and functionally mimic the binding surface of the parent peptide while exhibiting significantly decreased susceptibility to proteolysis. The tightest VEGF-binding ?/?-peptide inhibits the VEGF165-induced proliferation of human umbilical vein endothelial cells. We demonstrate the versatility of this strategy by showing how principles underlying VEGF signaling inhibitors can be rapidly extended to produce Z-domain-mimetic ?/?-peptides that bind to two other protein partners, IgG and tumor necrosis factor-?. Because well-established selection techniques can identify high-affinity Z-domain derivatives from large DNA-encoded libraries, our findings should enable the design of biostable ?/?-peptides that bind tightly and specifically to diverse targets of biomedical interest. Such reagents would be useful for diagnostic and therapeutic applications. PMID:25825775

Checco, James W; Kreitler, Dale F; Thomas, Nicole C; Belair, David G; Rettko, Nicholas J; Murphy, William L; Forest, Katrina T; Gellman, Samuel H

2015-04-14

306

Virus-host interactions in persistently FMDV-infected cells derived from bovine pharynx  

Technology Transfer Automated Retrieval System (TEKTRAN)

Foot-and-mouth disease virus (FMDV) produces a disease in cattle characterized by vesicular lesions and a persistent infection with asymptomatic low-level production of virus. Here we describe the establishment of a persistently infected primary cell culture derived from bovine pharynx tissue (PBPT)...

307

O glycosylation of an Sp1-derived peptide blocks known Sp1 protein interactions.  

PubMed Central

The O-linked N-acetylglucosamine (O-GlcNAc) modification of proteins is dynamic and abundant in the nucleus and cytosol. Several transcription factors, including Sp1, have been shown to contain this modification; however, the functional role of O-GlcNAc in these proteins has not been determined. In this paper we describe the use of the previously characterized glutamine-rich transactivation domain of Sp1 (B-c) as a model to investigate the role of O-GlcNAc in Sp1's transcriptionally relevant protein-to-protein interactions with the TATA-binding-protein-associated factor (TAF110) and holo-Sp1. When the model Sp1 peptide was overexpressed in primate cells, this 97-amino-acid domain of Sp1 was found to contain a dominant O-GlcNAc residue at high stoichiometry, which allowed the mapping and mutagenesis of this glycosylation site. In vitro interaction studies between this segment of Sp1 and Drosophila TAF110 or holo-Sp1 indicate that the O-GlcNAc modification functions to inhibit the largely hydrophobic interactions between these proteins. In HeLa cells, the mutation at the mapped glycosylation site was permissive for transcriptional activation. We propose the hypothesis that the removal of O-GlcNAc from an interaction domain can be a signal for protein association. O-GlcNAc may thereby prevent untimely and ectopic interactions. PMID:9343410

Roos, M D; Su, K; Baker, J R; Kudlow, J E

1997-01-01

308

Effect of biologically active substances derived from hydrobionts of the Pacific Ocean on parameters of lipid metabolism during experimental hypercholesterolemia.  

PubMed

We studied the effect of biologically active substances derived from hydrobionts, namely maristim (natural product from sea urchin roe) and fucolam (polysaccharides of fucoidan and calcium alginate from brown algae) on blood biochemistry in the mouse model of nutritional hypercholesterolemia. Maristim and fucolam are found to be capable to normalize the levels of the major indicators of lipid and carbohydrate metabolism and aminotransferase enzyme activity in terms of atherogenic load. Correction action of biologically active substances is more expressed in combined application. Identified experimentally normalizing effects of maristim and on lipid and carbohydrate metabolism allow us to recommend the further study in clinical trials of these biologically active substances and based on them additives. PMID:25430644

Kuznetsova, T A; Kryzhanovskii, S P; Bogdanovich, L N; Besednova, N N

2014-12-01

309

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

310

On the Existence of Parameter-Sensitive Regions: Resonant Interaction between Finite-Amplitude and Infinitesimal Periodic Solitons in the Davey–Stewartson II Equation  

NASA Astrophysics Data System (ADS)

There is a very small but finite amplitude periodic soliton (an infinitesimal periodic soliton) that interacts resonantly with a finite-amplitude periodic soliton under certain conditions. It is shown here that there are certain parameter-sensitive regions in the parameter space of the two-periodic-soliton solution where the interaction between the two periodic solitons undergoes a marked change to a small parameter change. Such regions exist near the intersections of two planes on which the conditions of a singular interaction are satisfied. The resonance between a finite-amplitude periodic soliton and an infinitesimal periodic soliton is shown to be responsible for the singular interactions with parameters in these parameter-sensitive regions.

Arai, Takahito; Tajiri, Masayoshi

2015-02-01

311

Interaction of Earthquakes and Aseismic Slip: Insights From 3D Fault Models Governed by Lab-Derived Friction Laws  

NASA Astrophysics Data System (ADS)

Recent improvements in availability and quality of seismic and geodetic data have revealed complex interactions of seismic and aseismic slip. This rich information, interpreted through modeling, can help us understand mechanics and physics of faults. Our simulation approach (Lapusta and Liu, 2008) produces spontaneous long-term fault slip and the resulting stress redistribution with full inclusion of inertial effects during simulated earthquakes in the context of a 3D fault model. The approach incorporates laboratory- derived rate and state friction laws, involves slow, tectonic-like loading, resolves all stages of seismic and aseismic slip, and results in realistic rupture speeds, slip velocities, and stress drops. We use the simulations to study two phenomena that arise due to interaction of seismic and aseismic slip: (i) supershear transition in 3D models due to rheological boundaries and (ii) mechanics of small repeating earthquakes. In our simulations, aseismic slip in creeping regions concentrates stress at rheological boundaries and promotes supershear transition during dynamic events (Liu and Lapusta, 2008). Transition of earthquakes from subshear to supershear speeds has important implications for strong ground motion and fault properties. Simulations of supershear transition are typically done in models of single events on linear slip- weakening faults. We simulate long-term seismic and aseismic slip on a strike-slip fault with a rectangular velocity-weakening (VW) region surrounded by velocity-strengthening (VS) regions. Existence of shallow and deeper VS regions is supported by lab friction studies as well as observations of interseismic creep, postseismic slip, limits on the depth extent of seismicity, and clustering of small events. In our simulations, steady slip throughout the interseismic period in the VS areas concentrates stress next to rheological boundaries and promotes faster rupture speeds and local supershear propagation of dynamic events. Under a range of conditions, this local behavior causes the entire rupture to become supershear. Our modeling of small repeating earthquakes reproduces several observational constraints, including their nontrivial scaling of seismic moment with the recurrence time (Chen and Lapusta, 2008). In our 3D model, a small circular patch with velocity-weakening friction is surrounded by a much larger velocity-strengthening region. When the patch size is smaller than the nucleation size implied by the underlying rate and state formulation, all slip on the patch is aseismic. For larger patch sizes, small repeating events occur, with slip rates of the order of 1 m/s and sharp stress drops; however, the patch also experiences significant aseismic slip. By varying the patch radius, we are able to produce repeating earthquakes that (i) reproduce the observed scaling T? M01/6 of the repeat time T and seismic moment M0 and (ii) have source dimensions and stress drops typical for earthquakes of comparable sizes and similar to recent inversions for Parkfield repeaters. Remarkably, the scaling T? M01/6 is independent of the variation, within a factor of 4, of rate and state parameters a and b. The scaling is also reproduced in a model with a rectangular velocity-weakening patch and with quasi-dynamic approach.

Lapusta, N.; Liu, Y.; Chen, T.

2008-12-01

312

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, Péter; Vella, Michael; Gulyás, Attila I.; Freund, Tamás F.; Káli, Szabolcs

2014-01-01

313

Direct Interaction between Scaffolding Proteins RACK1 and 14-3-3? Regulates Brain-derived Neurotrophic Factor (BDNF) Transcription*  

PubMed Central

RACK1 is a scaffolding protein that spatially and temporally regulates numerous signaling cascades. We previously found that activation of the cAMP signaling pathway induces the translocation of RACK1 to the nucleus. We further showed that nuclear RACK1 is required to promote the transcription of the brain-derived neurotrophic factor (BDNF). Here, we set out to elucidate the mechanism underlying cAMP-dependent RACK1 nuclear translocation and BDNF transcription. We identified the scaffolding protein 14-3-3? as a direct binding partner of RACK1. Moreover, we found that 14-3-3? was necessary for the cAMP-dependent translocation of RACK1 to the nucleus. We further observed that the disruption of RACK1/14-3-3? interaction with a peptide derived from the RACK1/14-3-3? binding site or shRNA-mediated 14-3-3? knockdown inhibited cAMP induction of BDNF transcription. Together, these data reveal that the function of nuclear RACK1 is mediated through its interaction with 14-3-3?. As RACK1 and 14-3-3? are two multifunctional scaffolding proteins that coordinate a wide variety of signaling events, their interaction is likely to regulate other essential cellular functions. PMID:22069327

Neasta, Jérémie; Kiely, Patrick A.; He, Dao-Yao; Adams, David R.; O'Connor, Rosemary; Ron, Dorit

2012-01-01

314

Direct interaction between scaffolding proteins RACK1 and 14-3-3? regulates brain-derived neurotrophic factor (BDNF) transcription.  

PubMed

RACK1 is a scaffolding protein that spatially and temporally regulates numerous signaling cascades. We previously found that activation of the cAMP signaling pathway induces the translocation of RACK1 to the nucleus. We further showed that nuclear RACK1 is required to promote the transcription of the brain-derived neurotrophic factor (BDNF). Here, we set out to elucidate the mechanism underlying cAMP-dependent RACK1 nuclear translocation and BDNF transcription. We identified the scaffolding protein 14-3-3? as a direct binding partner of RACK1. Moreover, we found that 14-3-3? was necessary for the cAMP-dependent translocation of RACK1 to the nucleus. We further observed that the disruption of RACK1/14-3-3? interaction with a peptide derived from the RACK1/14-3-3? binding site or shRNA-mediated 14-3-3? knockdown inhibited cAMP induction of BDNF transcription. Together, these data reveal that the function of nuclear RACK1 is mediated through its interaction with 14-3-3?. As RACK1 and 14-3-3? are two multifunctional scaffolding proteins that coordinate a wide variety of signaling events, their interaction is likely to regulate other essential cellular functions. PMID:22069327

Neasta, Jérémie; Kiely, Patrick A; He, Dao-Yao; Adams, David R; O'Connor, Rosemary; Ron, Dorit

2012-01-01

315

Shuttle derived atmospheric density model. Part 1: Comparisons of the various ambient atmospheric source data with derived parameters from the first twelve STS entry flights, a data package for AOTV atmospheric development  

NASA Technical Reports Server (NTRS)

The ambient atmospheric parameter comparisons versus derived values from the first twelve Space Shuttle Orbiter entry flights are presented. Available flights, flight data products, and data sources utilized are reviewed. Comparisons are presented based on remote meteorological measurements as well as two comprehensive models which incorporate latitudinal and seasonal effects. These are the Air Force 1978 Reference Atmosphere and the Marshall Space Flight Center Global Reference Model (GRAM). Atmospheric structure sensible in the Shuttle flight data is shown and discussed. A model for consideration in Aero-assisted Orbital Transfer Vehicle (AOTV) trajectory analysis, proposed to modify the GRAM data to emulate Shuttle experiments.

Findlay, J. T.; Kelly, G. M.; Troutman, P. A.

1984-01-01

316

Training and Deriving Precalculus Relations: A Small-Group, Web-Interactive Approach  

ERIC Educational Resources Information Center

A small-group, web-interactive approach to teaching precalculus concepts was investigated. Following an online pretest, 3 participants were given a brief (15 min) presentation on the details of reciprocal math relations and how they operate on the coordinate axes. During baseline, participants were tested regarding their ability to construct…

McGinty, Jenny; Ninness, Chris; McCuller, Glen; Rumph, Robin; Goodwin, Andrea; Kelso, Ginger; Lopez, Angie; Kelly, Elizabeth

2012-01-01

317

Modeling host interactions with hepatitis B virus using primary and induced pluripotent stem cell-derived  

E-print Network

Modeling host interactions with hepatitis B virus using primary and induced pluripotent stem cell and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065; b of Hepatitis C, Weill Cornell Medical College, New York, NY 10065; and f Broad Institute of MIT and Harvard

Bhatia, Sangeeta

318

Cytotoxic and DNA-topoisomerase effects of lapachol amine derivatives and interactions with DNA  

Microsoft Academic Search

The cytotoxic activity of amino (3a-e), aza-1-antraquinone (4a-e) lapachol derivatives against Ehrlich carcinoma and human K562 leukemia cells was investigated. Cell viability was determined using MTT assay, after 48 (Ehrlich) or 96 h (K562) of culture, and vincris- tine (for K562 leukemia) and quercetin (for Ehrlich carcinoma) were used as positive controls. The results showed dose-dependent growth- inhibiting activities and

A. Esteves-Souza; D. V. Figueiredo; A. Esteves; C. A. Câmara; M. D. Vargas; A. C. Pinto; A. Echevarria

2007-01-01

319

Determination of the parameters of binding between lipopolysaccharide and chitosan and its N-acetylated derivative using a gravimetric piezoquartz biosensor.  

PubMed

The interaction of endotoxin (lipopolysaccharide - LPS) with low molecular weight chitosan (5.5kDa), its N-acylated derivative and chitoliposomes was studied using a gravimetric piezoelectric quartz crystal microbalance biosensor. The optimal conditions for the formation of a biolayer based on immobilized LPS on the resonator surface and its regeneration were elaborated. The association and dissociation rate constants for LPS binding to chitosans were determined and the affinity constants (Kaf) were calculated based on the data on changes in the oscillation frequency of the quartz crystal resonator. The Kaf values correlated with the ones obtained using other methods. The affinity of N-acylated chitosan binding to LPS was higher than that of the parent chitosan binding to LPS. Based on the results obtained, we suggest that water-soluble N-acylated derivatives of chitosan with low degree of substitution of amino groups could be useful compounds for endotoxin binding and neutralization. PMID:25637889

Naberezhnykh, G A; Gorbach, V I; Kalmykova, E N; Solov'eva, T F

2015-03-01

320

Interaction of human adipose tissue-derived mesenchymal stromal cells with breast cancer cells.  

PubMed

Human adipose tissue was shown to be a very attractive source of mesenchymal stromal cells that have a wide scale of potential applications in reconstructive plastic surgery and regenerative medicine. However, these cells were described to have profound effects on biological behaviour of tumour cells. The aim of this study was to analyze the influence of adipose tissue-derived human mesenchymal stromal cells (AT-MSC) on the proliferation of breast cancer cells. We have tested proliferation of three different human breast cancer cell lines under the influence of AT-MSC derived soluble factors as well as in the direct cocultures. These data were supplemented with the expression analysis of cytokines and their cognate receptors on the target cells. We have observed stimulation of proliferation in breast cancer cells MDA-MB-361, T47D and EGFP-MCF7. AT-MSC were found to secrete wide scale of cytokines, chemokines and growth factors, thus we concluded that this pro-proliferative effect was a result of their synergistic action. These data bring out a need to evaluate whether primary breast tumour derived human cells would respond to these type of stimuli in a similar manner in order to exclude any potential clinical risk related to the application of human mesenchymal stromal cells under the context of patient with history of breast cancer malignancy. PMID:21744988

Kucerova, L; Kovacovicova, M; Polak, S; Bohac, M; Fedeles, J; Palencar, D; Matuskova, M

2011-01-01

321

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

322

Derivative couplings and analytic gradients for diabatic states, with an implementation for Boys-localized configuration-interaction singles  

NASA Astrophysics Data System (ADS)

We demonstrate that Boys-localized diabatic states do indeed exhibit small derivative couplings, as is required of quasidiabatic states. In doing so, we present a general formalism for calculating derivative couplings and analytic gradients for diabatic states. We then develop additional equations specific to the case of Boys-localized configuration-interaction singles (CIS)—in particular, the analytic gradient of the CIS dipole matrix—and we validate our implementation against finite-difference results. In a forthcoming paper, we will publish additional algorithmic and computational details and apply our method to the Closs energy-transfer systems as a further test of the validity of Boys-localized diabatic states.

Fatehi, Shervin; Alguire, Ethan; Subotnik, Joseph E.

2013-09-01

323

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

NASA Astrophysics Data System (ADS)

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 states and turbulent fluxes collected over nine sites in the U.S. Southern Great Plains. We quantify changes in the pattern of sensitive parameters, the amount and nature of the interaction between parameters, and the covariance structure of the distribution of behavioral parameter sets. Using Sobol''s total and first-order sensitivity indexes, we show that few parameters directly control the variance of the model response. Significant parameter interaction occurs. Optimal parameter values differ between models, and the relationships between parameters also change. GW decreases unwarranted parameter interaction and appears to improve model realism, especially at wetter study sites. DV increases parameter interaction and decreases identifiability, implying it is overparameterized and/or underconstrained. At a wet site, GW has two functional modes: one that mimics STD and a second in which GW improves model function by decoupling direct evaporation and base flow. Unsupervised classification of the posterior distributions of behavioral parameter sets cannot group similar sites based solely on soil or vegetation type, helping to explain why transferability between sites and models is not straightforward. Our results suggest that the a priori assignment of parameters should also consider the climatic conditions of a study location.

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

2010-01-01

324

Early epidemic dynamics of the west african 2014 ebola outbreak: estimates derived with a simple two-parameter model.  

PubMed

The 2014 West African Ebola virus outbreak, now more correctly referred to as an epidemic, is the largest ever to occur. As of August 28, 2014, concerns have been raised that control efforts, particularly in Liberia, have been ineffective, as reported case counts continue to increase. Limited data are available on the epidemiology of the outbreak. However, reported cumulative incidence data as well as death counts are available for Guinea, Sierra Leone, Liberia and Nigeria. We utilized a simple, two parameter mathematical model of epidemic growth and control, to characterize epidemic growth patterns in West Africa, to evaluate the degree to which the epidemic is being controlled, and to assess the potential implications of growth patterns for epidemic size. Models demonstrated good fits to data. Overall basic reproductive number (R0) for the epidemic was estimated to be between 1.6 and 2.0, consistent with prior outbreaks. However, we identified only weak evidence for the occurrence of epidemic control in West Africa as a whole, and essentially no evidence for control in Liberia (though slowing of growth was seen in Guinea and Sierra Leone). It is projected that small reductions in transmission would prevent tens of thousands of future infections. These findings suggest that there is an extraordinary need for improved control measures for the 2014 Ebola epidemic, especially in Liberia, if catastrophe is to be averted. PMID:25642358

Fisman, David; Khoo, Edwin; Tuite, Ashleigh

2014-01-01

325

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

326

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

327

Repeated forced swimming impairs prepulse inhibition and alters brain-derived neurotrophic factor and astroglial parameters in rats.  

PubMed

Glutamate perturbations and altered neurotrophin levels have been strongly associated with the neurobiology of neuropsychiatric disorders. Environmental stress is a risk factor for mood disorders, disrupting glutamatergic activity in astrocytes in addition to cognitive behaviours. Despite the negative impact of stress-induced neuropsychiatric disorders on public health, the molecular mechanisms underlying the response of the brain to stress has yet to be fully elucidated. Exposure to repeated swimming has proven useful for evaluating the loss of cognitive function after pharmacological and behavioural interventions, but its effect on glutamate function has yet to be fully explored. In the present study, rats previously exposed to repeated forced swimming were evaluated using the novel object recognition test, object location test and prepulse inhibition (PPI) test. In addition, quantification of brain-derived neurotrophic factor (BDNF) mRNA expression and protein levels, glutamate uptake, glutathione, S100B, GluN1 subunit of N-methyl-D-aspartate receptor and calmodulin were evaluated in the frontal cortex and hippocampus after various swimming time points. We found that swimming stress selectively impaired PPI but did not affect memory recognition. Swimming stress altered the frontal cortical and hippocampal BDNF expression and the activity of hippocampal astrocytes by reducing hippocampal glutamate uptake and enhancing glutathione content in a time-dependent manner. In conclusion, these data support the assumption that astrocytes may regulate the activity of brain structures related to cognition in a manner that alters complex behaviours. Moreover, they provide new insight regarding the dynamics immediately after an aversive experience, such as after behavioural despair induction, and suggest that forced swimming can be employed to study altered glutamatergic activity and PPI disruption in rodents. PMID:25444867

Borsoi, Milene; Antonio, Camila Boque; Müller, Liz Girardi; Viana, Alice Fialho; Hertzfeldt, Vivian; Lunardi, Paula Santana; Zanotto, Caroline; Nardin, Patrícia; Ravazzolo, Ana Paula; Rates, Stela Maris Kuze; Gonçalves, Carlos-Alberto

2015-01-01

328

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

329

Lipoprotein lipase enhances the interaction of low density lipoproteins with artery-derived extracellular matrix proteoglycans.  

PubMed

The association of plasma low density lipoproteins (LDL) with arterial proteoglycans (PG) is of key importance in LDL retention and modification in the artery wall. Lipoprotein lipase (LpL), the rate-limiting enzyme for hydrolysis of lipoprotein triglyceride, is known to bind both LDL and arterial PG. In the presence of LpL, cellular internalization and degradation of LDL is enhanced by a pathway initiated by interaction of LDL with a cell surface heparan sulfate proteoglycan. To determine whether LpL enhances the binding of LDL to arterial chondroitin sulfate (CS)PG and dermatan sulfate (DS)PG, the major extracellular PG of the artery wall, a microtiter plate assay was used to study LpL-PG-LDL interactions. Binding of LDL to both CSPG and DSPG was increased in the presence of LpL but differential effects were seen for the two PG. LpL enhanced the binding of LDL to CSPG a maximum of 20% and to DSPG a maximum of 40%. Heparin displacement of PG binding suggested a greater binding strength for DSPG-LpL-LDL with 0.25 micrograms heparin required to displace 50% of DSPG compared to 0.01 micrograms to displace 50% of CSPG. The greater enhancement of DSPG-LDL interaction by LpL is of particular interest since increases in DSPG correlate with the accumulation of aortic cholesterol. These data suggest that lipoprotein lipase may enhance the interaction of plasma low density lipoprotein with arterial chondroitin sulfate proteoglycan and dermatan sulfate proteoglycan and thus facilitate low density lipoprotein retention in the artery wall. PMID:8371063

Edwards, I J; Goldberg, I J; Parks, J S; Xu, H; Wagner, W D

1993-07-01

330

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

331

Molecular interactions between fenoterol stereoisomers and derivatives and the ??-adrenergic receptor binding site studied by docking and molecular dynamics simulations.  

PubMed

The ?2 adrenergic receptor (?2-AR) has become a model system for studying the ligand recognition process and mechanism of the G protein coupled receptors activation. In the present study stereoisomers of fenoterol and some of its derivatives (N?=?94 molecules) were used as molecular probes to identify differences in stereo-recognition interactions between ?2-AR and structurally similar agonists. The present study aimed at determining the 3D molecular models of the fenoterol derivative-?2-AR complexes. Molecular models of ?2-AR have been developed by using the crystal structure of the human ?2-AR T4 lysozyme fusion protein with bound (S)-carazolol (PDB ID: 2RH1) and more recently reported structure of a nanobody-stabilized active state of the ?2-AR with the bound full agonist BI-167107 (PDB ID: 3P0G). The docking procedure allowed us to study the similarities and differences in the recognition binding site(s) for tested ligands. The agonist molecules occupied the same binding region, between TM III, TM V, TM VI and TM VII. The residues identified by us during docking procedure (Ser203, Ser207, Asp113, Lys305, Asn312, Tyr308, Asp192) were experimentally indicated in functional and biophysical studies as being very important for the agonist-receptor interactions. Moreover, the additional space, an extension of the orthosteric pocket, was identified and described. Furthermore, the molecular dynamics simulations were used to study the molecular mechanism of interaction between ligands ((R,R')- and (S,S')-fenoterol) and ?2-AR. Our research offers new insights into the ligand stereoselective interaction with one of the most important GPCR member. This study may also facilitate the design of improved selective medications, which can be used to treat, prevent and control heart failure symptoms. PMID:24043542

Plazinska, Anita; Kolinski, Michal; Wainer, Irving W; Jozwiak, Krzysztof

2013-11-01

332

Host-microbial interactions in the metabolism of therapeutic and diet-derived xenobiotics.  

PubMed

Our associated microbial communities play a critical role in human health and predisposition to disease, but the degree to which they also shape therapeutic interventions is not well understood. Here, we integrate results from classic and current studies of the direct and indirect impacts of the gut microbiome on the metabolism of therapeutic drugs and diet-derived bioactive compounds. We pay particular attention to microbial influences on host responses to xenobiotics, adding to the growing consensus that treatment outcomes reflect our intimate partnership with the microbial world, and providing an initial framework from which to consider a more comprehensive view of pharmacology and nutrition. PMID:25105361

Carmody, Rachel N; Turnbaugh, Peter J

2014-10-01

333

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

334

Fundamental parameters of the close interacting binary HD 170582 and its luminous accretion disc  

NASA Astrophysics Data System (ADS)

We present a spectroscopic and photometric study of the double period variable HD 170582. Based on the study of the ASAS V-band light curve, we determine an improved orbital period of 16.871 77 ± 0.020 84 d and a long period of 587 d. We disentangled the light curve into an orbital part, determining ephemerides and revealing orbital ellipsoidal variability with unequal maxima, and a long cycle, showing quasi-sinusoidal changes with amplitude ?V= 0.1 mag. Assuming synchronous rotation for the cool stellar component and semidetached configuration we find a cool evolved star of M2 = 1.9 ± 0.1 M?, T2 = 8000 ± 100 K and R2 = 15.6 ± 0.2 R?, and an early B-type dwarf of M1 = 9.0 ± 0.2 M?. The B-type star is surrounded by a geometrically and optically thick accretion disc of radial extension 20.8 ± 0.3 R? contributing about 35 per cent to the system luminosity at the V band. Two extended regions located at opposite sides of the disc rim, and hotter than the disc by 67 and 46 per cent, fit the light-curve asymmetries. The system is seen under inclination 67.4° ± 0.4° and it is found at a distance of 238 ± 10 pc. Specially interesting is the double line nature of He I 5875; two absorption components move in antiphase during the orbital cycle; they can be associated with the shock regions revealed by the photometry. The radial velocity of one of the He I 5875 components closely follows the donor radial velocity, suggesting that the line is formed in a wind emerging near the stream-disc interacting region.

Mennickent, R. E.; Djuraševi?, G.; Cabezas, M.; Cséki, A.; Rosales, J. G.; Niemczura, E.; Araya, I.; Curé, M.

2015-04-01

335

Interaction of aminoadamantane derivatives with the influenza A virus M2 channel-docking using a pore blocking model.  

PubMed

Interaction of aminoadamantanes with the influenza A virus M2 proton channel was analyzed by docking simulations of a series of synthetic aminoadamantane derivatives, of differing binding affinity, into the crystal structure of the transmembrane (M2TM) pore. The pore blocking model tested in the 'gas phase' describes qualitatively the changes on the relative binding affinities of the compounds (although a series of highly hydrophobic ligands which seem to have little capacity for different specific interactions with their receptor). The docking calculations predicted poses in which the adamantane ring is surrounded mainly by the alkyl side chains of Val27 or Ala30 and the ligand's amino group is generally hydrogen bonded with hydroxyls of Ser31 or carbonyls of Val27 or carbonyls of Ala30, the former (Ser31) being the most stable and most frequently observed. The binding of the ligand is a compromise between hydrogen bonding ability, which is elevated by a primary amino group, and apolar interactions, which are increased by the ability of the lipophilic moiety to adequately fill a hydrophobic pocket within the M2TM pore. A delicate balance of these hydrophobic contributions is required for optimal interaction. PMID:20570509

Eleftheratos, Stelios; Spearpoint, Philip; Ortore, Gabriella; Kolocouris, Antonios; Martinelli, Adriano; Martin, Stephen; Hay, Alan

2010-07-15

336

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

337

Method for estimating local lattice distortions near a magnetic ion based on the parameters of the ligand hyperfine interaction: Ce 3+ in the fluorite homologous series  

Microsoft Academic Search

A method is suggested for estimating local lattice distortions near a paramagnetic center by using the parameters determined\\u000a from experimental tensors of the ligand hyperfine interaction with surrounding nuclei through the use of a simple mathematical\\u000a procedure. In general, a tensor with nine independent components can be unambiguously reduced to nine independent parameters\\u000a characterizing the hyperfine interaction: the isotropic part,

Ts. A. Gavasheli; D. M. Daraseliya; D. L. Dzhaparidze; R. I. Mirianashvili; O. V. Romelashvili; T. I. Sanadze

2002-01-01

338

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

339

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

340

Molecular dissection of the interactions of an antitumor interleukin-2-derived mutein on a phage display-based platform.  

PubMed

A mutein with stronger antitumor activity and lower toxicity than wild-type human interleukin-2 (IL-2) has been recently described. The rationale behind its design was to reinforce the immunostimulatory potential through the introduction of four mutations that would selectively disrupt the interaction with the IL-2 receptor alpha chain (thought to be critical for both IL-2-driven expansion of T regulatory cells and IL-2-mediated toxic effects). Despite the successful results of the mutein in several tumor models, characterization of its interactions was still to be performed. The current work, based on phage display of IL-2-derived variants, showed the individual contribution of each mutation to the impairment of alpha chain binding. A more sensitive assay, based on the ability of phage-displayed IL-2 variants to induce proliferation of the IL-2-dependent CTLL-2 cell line, revealed differences between the mutated variants. The results validated the mutein design, highlighting the importance of the combined effects of the four mutations. The developed phage display-based platform is robust and sensitive, allows a fast comparative evaluation of multiple variants, and could be broadly used to engineer IL-2 and related cytokines, accelerating the development of cytokine-derived therapeutics. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25683569

Rojas, Gertrudis; Carmenate, Tania; Leon, Kalet

2015-04-01

341

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

342

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

343

Microwave spectroscopic studies of molecular recognition: Analysis of diastereomeric interactions between ethanol and oxirane derivatives  

NASA Astrophysics Data System (ADS)

High resolution microwave spectroscopy complimented by ab initio calculations has been used to elucidate the diastereomeric interactions in a set of small model complexes. Ethanol, a transient chiral alcohol, was combined with oxirane (achiral), methyl-oxiraneootnotetextmark[1] (1 stereocenter) and trans-2,3-dimethyloxirane (2 stereocenters) to form hydrogen-bonded 1:1 complexes. The rotational constants of two conformers of ethanoloxirane, six conformers of ethanolmethyl-oxirane and three conformers of ethanoltrans-2,3-dimethyloxirane have been determined and the relative stability order of the conformers has been established. The dependence of the observed intensity on pressure, nozzle temperature and different carrier gases has been investigated for the case of ethanoltrans-2,3-dimethyloxirane to give a first insight into the kinetical and thermodynamical influence on the formation of different conformers. The step-by-step methyl addition to oxirane helps to unravel the diastereomeric interactions at play via analysis of the subtle energy differences between each set of conformers, allowing for a detailed understanding of molecular recognition in this benchmark system.ootnotetextmark[1]Nicole Borho, Yunjie Xu, Angew. Chem., 2006, (VIP paper, Published Online: 17 Nov 2006, DOI: 10.1002/anie.200603809).

Borho, Nicole; Xu, Yunjie

2007-06-01

344

A 3D interactive method for estimating body segmental parameters in animals: Application to the turning and running performance of Tyrannosaurus rex  

Microsoft Academic Search

We developed a method based on interactive B-spline solids for estimating and visualizing biomechanically important parameters for animal body segments. Although the method is most useful for assessing the importance of unknowns in extinct animals, such as body contours, muscle bulk, or inertial parameters, it is also useful for non-invasive measurement of segmental dimensions in extant animals. Points measured directly

John R. Hutchinson; Victor Ng-Thow-Hing; Frank C. Anderson

2007-01-01

345

Predicting forest structural parameters using the image texture derived from WorldView-2 multispectral imagery in a dryland forest, Israel  

NASA Astrophysics Data System (ADS)

Estimation of forest structural parameters by field-based data collection methods is both expensive and time consuming. Satellite remote sensing is a low-cost alternative in modeling and mapping structural parameters in large forest areas. The current study investigates the potential of using WordView-2 multispectral satellite imagery for predicting forest structural parameters in a dryland plantation forest in Israel. The relationships between image texture features and the several structural parameters such as Number of Trees (NT), Basal Area (BA), Stem Volume (SV), Clark-Evans Index (CEI), Diameter Differentiation Index (DDI), Contagion Index (CI), Gini Coefficient (GC), and Standard Deviation of Diameters at Breast Heights (SDDBH) were examined using correlation analyses. These variables were obtained from 30 m × 30 m square-shaped plots. The Standard Deviation of Gray Levels (SDGL) as a first order texture feature and the second order texture variables based on Gray Level Co-occurrence Matrix (GLCM) were calculated for the pixels that corresponds to field plots. The results of the correlation analysis indicate that the forest structural parameters are significantly correlated with the image texture features. The highest correlation coefficients were calculated for the relationships between the SDDBH and the contrast of red band ( r = 0.75, p < 0.01), the BA and the entropy of blue band ( r = 0.73, p < 0.01), and the GC and the contrast of blue band ( r = 0.71, p < 0.01). Each forest structural parameter was modeled as a function of texture measures derived from the satellite image using stepwise multi linear regression analyses. The determination coefficient ( R2) and root mean square error (RMSE) values of the best fitting models, respectively, are 0.38 and 109.56 ha -1 for the NT; 0.54 and 1.79 m 2 ha -1 for the BA; 0.42 and 27.18 m 3 ha -1 for the SV; 0.23 and 0.16 for the CEI; 0.32 and 0.05 for the DDI; 0.25 and 0.06 for the CI; 0.50 and 0.05 for the GC; and 0.67 and 0.70 for the SDDBH. The leave-one-out cross-validation technique was applied for validation of the best-fitted models ( R2 > 0.50). In conclusion, cross-validated statistics confirmed that the structural parameters including the BA, SDDBH, and GC can be predicted and mapped with a reasonable accuracy using the texture features extracted from the spectral bands of WorldView-2 image.

Ozdemir, Ibrahim; Karnieli, Arnon

2011-10-01

346

Analytic first derivatives for general coupled-cluster and configuration interaction models  

NASA Astrophysics Data System (ADS)

A general method for the analytic computation of energy gradients within coupled-cluster (CC) and configuration interaction (CI) theory is presented. The proposed algorithm is formulated in the framework of our recent string-based many-body formalism and allows to handle wave functions truncated at arbitrary excitation level or including excitations selected via a complete active space. The considered wave function classes include any single-reference as well as several multireference-type CC and CI ansätze and as a special case the full CI limit. The applicability of the proposed and implemented procedure is demonstrated by performing benchmark CC and CI gradient and property calculations up to full CI for H2O (1A1), HF (1?+), NH2 (2B1), and OH (2?) as well as for the transition state of the F+H2?HF+H reaction.

Kállay, Mihály; Gauss, Jürgen; Szalay, Péter G.

2003-08-01

347

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

348

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

349

Influence of gold(I) complexes involving adenine derivatives on major drug-drug interaction pathway.  

PubMed

A series of considerably anti-inflammatory active gold(I) mixed-ligand complexes, involving the benzyl-substituted derivatives of N6-benzyladenine (HLn) and triphenylphosphine (PPh3) as ligands and having the general formula [Au(Ln)(PPh3)]·xH2O (1-4; n=1-4 and x=0-1), was evaluated for the ability to influence the expression of CYP1A1/2 and CYP3A4 and transcriptional activity of glucocorticoid (GR) and aryl hydrocarbon (AhR) receptors in primary human hepatocytes and HepG2 cells. In both tests, evaluating the ability of the complexes to modulate the expression of CYP1A1, CYP1A2 and CYP3A4 in primary human hepatocytes and influence the transcriptional activity of AhR and GR in the reporter cell lines, no negative influence on the major drug-metabolizing cytochrome P450 isoenzymes and their signaling pathway (through GR and AhR receptors) was observed. These positive findings revealed another substantial evidence that could lead to utilization of the complexes as effective and relatively safe drugs for the treatment of hard-to-treat inflammation-related diseases, such as rheumatoid arthritis, comparable or even better than clinically used gold-containing drug Auranofin. PMID:24157406

Dvo?ák, Zden?k; Novotná, Aneta; Van?o, Ján; Trávní?ek, Zden?k

2013-12-01

350

Physiochemical characterization of the nisin-membrane interaction with liposomes derived from Listeria monocytogenes.  

PubMed Central

Mechanistic information about the bacteriocin nisin was obtained by examining the efflux of 5(6)-carboxy-fluorescein from Listeria monocytogenes-derived liposomes. The initial leakage rate (percentage of efflux per minute) of the entrapped dye was dependent on both nisin and lipid concentrations. At all nisin concentrations tested, 5(6)-carboxyfluorescein efflux plateaued before all of the 5(6)-carboxyfluorescein was released (suggesting that pore formation was transient), but efflux resumed when more nisin was added. Isotherms for the binding of nisin to liposomes constructed on the basis of the Langmuir isotherm gave an apparent binding constant of 6.2 x 10(5)M(-1) at pH 6.0. The critical number of nisin molecules required to induce efflux from liposomes at pH 6.0 was approximately 7,000 molecules per liposome. The pH affected the 5(6)-carboxyfluorescein leakage rates, with higher pH values resulting in higher leakage rates. The increased leakage rate observed at higher pH values was not due to an increase in the binding affinity of the nisin molecules towards the liposomal membrane. Rather, the critical number of nisin molecules required to induce activity was decreased (approximately 1,000 nisin molecules per liposome at pH 7.0). These data are consistent with a poration mechanism in which the ionization state of histidine residues in nisin plays an important role in membrane permeabilization. PMID:8593036

Winkowski, K; Ludescher, R D; Montville, T J

1996-01-01

351

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

352

Sequential identification of model parameters by derivative double two-dimensional correlation spectroscopy and calibration-free approach for chemical reaction systems.  

PubMed

A sequential identification approach by two-dimensional (2D) correlation analysis for the identification of a chemical reaction model, activation, and thermodynamic parameters is presented in this paper. The identification task is decomposed into a sequence of subproblems. The first step is the construction of a reaction model with the suggested information by model-free 2D correlation analysis using a novel technique called derivative double 2D correlation spectroscopy (DD2DCOS), which enables one to analyze intensities with nonlinear behavior and overlapped bands. The second step is a model-based 2D correlation analysis where the activation and thermodynamic parameters are estimated by an indirect implicit calibration or a calibration-free approach. In this way, a minimization process for the spectral information by sample-sample 2D correlation spectroscopy and kinetic hard modeling (using ordinary differential equations) of the chemical reaction model is carried out. The sequential identification by 2D correlation analysis is illustrated with reference to the isomeric structure of diphenylurethane synthesized from phenylisocyanate and phenol. The reaction was investigated by FT-IR spectroscopy. The activation and thermodynamic parameters of the isomeric structures of diphenylurethane linked through a hydrogen bonding equilibrium were studied by means of an integration of model-free and model-based 2D correlation analysis called a sequential identification approach. The study determined the enthalpy (?H = 15.25 kJ/mol) and entropy (T?S = 13.20 kJ/mol) of C?O···H hydrogen bonding of diphenylurethane through direct calculation from the differences in the kinetic parameters (??(‡)H, -T??(‡)S) at equilibrium in the chemical reaction system. PMID:22924791

Spegazzini, Nicolas; Siesler, Heinz W; Ozaki, Yukihiro

2012-10-01

353

Food plant derived disease tolerance and resistance in a natural butterfly-plant-parasite interactions.  

PubMed

Organisms can protect themselves against parasite-induced fitness costs through resistance or tolerance. Resistance includes mechanisms that prevent infection or limit parasite growth while tolerance alleviates the fitness costs from parasitism without limiting infection. Although tolerance and resistance affect host-parasite coevolution in fundamentally different ways, tolerance has often been ignored in animal-parasite systems. Where it has been studied, tolerance has been assumed to be a genetic mechanism, unaffected by the host environment. Here we studied the effects of host ecology on tolerance and resistance to infection by rearing monarch butterflies on 12 different species of milkweed food plants and infecting them with a naturally occurring protozoan parasite. Our results show that monarch butterflies experience different levels of tolerance to parasitism depending on the species of milkweed that they feed on, with some species providing over twofold greater tolerance than other milkweed species. Resistance was also affected by milkweed species, but there was no relationship between milkweed-conferred resistance and tolerance. Chemical analysis suggests that infected monarchs obtain highest fitness when reared on milkweeds with an intermediate concentration, diversity, and polarity of toxic secondary plant chemicals known as cardenolides. Our results demonstrate that environmental factors-such as interacting species in ecological food webs-are important drivers of disease tolerance. PMID:23106703

Sternberg, Eleanore D; Lefèvre, Thierry; Li, James; de Castillejo, Carlos Lopez Fernandez; Li, Hui; Hunter, Mark D; de Roode, Jacobus C

2012-11-01

354

Tensor interaction limit derived from the ?-?-?[over ¯] correlation in trapped 8Li ions.  

PubMed

A measurement of the ?-?-?[over ¯] angular correlation in the Gamow-Teller decay (8)Li?(8)Be(*)+?[over ¯]+?, (8)Be(*)??+? 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 C(T) relative to that of the dominant axial-vector component C(A) of the electroweak interaction is limited to |C(T)/C(A)|<0.18 (95.5% confidence level). This experimental approach is facilitated by several favorable features of the (8)Li ? decay and has different systematic effects than the previous ?-?[over ¯] correlation results for a pure Gamow-Teller transition obtained from studying (6)He ? decay. PMID:23496705

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

355

Host-Parasite Interaction: Parasite-Derived and -Induced Proteases That Degrade Human Extracellular Matrix  

PubMed Central

Parasitic protozoa are among the most important pathogens worldwide. Diseases such as malaria, leishmaniasis, amoebiasis, giardiasis, trichomoniasis, and trypanosomiasis affect millions of people. Humans are constantly threatened by infections caused by these pathogens. Parasites engage a plethora of surface and secreted molecules to attach to and enter mammalian cells. The secretion of lytic enzymes by parasites into host organs mediates critical interactions because of the invasion and destruction of interstitial tissues, enabling parasite migration to other sites within the hosts. Extracellular matrix is a complex, cross-linked structure that holds cells together in an organized assembly and that forms the basement membrane lining (basal lamina). The extracellular matrix represents a major barrier to parasites. Therefore, the evolution of mechanisms for connective-tissue degradation may be of great importance for parasite survival. Recent advances have been achieved in our understanding of the biochemistry and molecular biology of proteases from parasitic protozoa. The focus of this paper is to discuss the role of protozoan parasitic proteases in the degradation of host ECM proteins and the participation of these molecules as virulence factors. We divide the paper into two sections, extracellular and intracellular protozoa. PMID:22792442

Piña-Vázquez, Carolina; Reyes-López, Magda; Ortíz-Estrada, Guillermo; de la Garza, Mireya; Serrano-Luna, Jesús

2012-01-01

356

Major histocompatibility complex independent T cell receptor-antigen interaction: functional analysis using fluorescein derivatives  

PubMed Central

We have isolated T cell receptor (TCR) cDNAs from fluorescein (FL)- specific human T cell clones (alpha FL beta FL), and transferred them to TCR beta- Jurkat cells in order to study direct FL-binding to the TCR. Using either FL-conjugated polymers (FL-polymer) or FL-substituted Sepharose beads, we are able to demonstrate the direct binding of antigen to the T cell surface, and the functional activation of the T cell transfectants. We present evidence against the involvement of major histocompatibility complex (MHC) molecules or antigen presentation in the interaction of FL with the alpha FL beta FL transfectants. Additionally, we have examined the effect of ring substitutions on the FL molecule as well as specific alterations of substituents attached to the 5' position, and we have found that all of them interfere with the functional recognition of the alpha FL beta FL TCR. These experiments demonstrate that TCRs like antibodies have intrinsic affinities for antigen, even without the involvement of MHC molecules. PMID:2056277

1991-01-01

357

Screening of the most relevant parameters for method development in ultra-high performance hydrophilic interaction chromatography.  

PubMed

The goal of the present work was to provide some guidelines for method development in hydrophilic interaction chromatography (HILIC). For this purpose, a training set of 82 representative pharmaceutical compounds possessing diverse polarity and including acidic, basic and neutral properties was analyzed. All these drugs were injected on five short HILIC columns packed with sub-2?m particles and dedicated for UHPLC (ultra-high performance liquid chromatography) operation. Four different pH conditions ranging from pH 3 to 6 were tested at two ionic strengths (10 and 50mmol/L) and finally, the reference organic modifier in HILIC, namely acetonitrile was modified with small amounts of methanol or isopropanol. From these experiments and using multivariate data analysis, it is clear that the stationary phase was the most relevant parameters for tuning selectivity in HILIC, since the types of interactions (i.e. dipole-dipole, hydrogen bonding and ion exchange) with analytes strongly vary between columns. Among the selected phases, the diol phase was the less interesting one, in terms of selectivity and peak shape. The zwitterionic phase was attractive, as it allowed a better retention of acidic compounds. Finally, the bare silica phase was the most versatile HILIC column packed with sub-2?m particles in terms of retention, peak shape and selectivity. Mobile phase pH was the other important parameter to achieve an appropriate selectivity and retention, even if it remains always difficult to assess precisely the mobile phase pH, analyte pKa and silanols pKa, when working with more 70% acetonitrile. Finally, buffer ionic strength and organic modifier nature could be considered as secondary parameters for HILIC method development. In conclusion, screening four different columns packed with sub-2?m particles at two mobile phase pH, using a fast gradient seems to be a good generic approach for initial HILIC method development. The total time for such a screening was estimated at ?1h, including reequilibration. PMID:23411147

Periat, Aurélie; Debrus, Benjamin; Rudaz, Serge; Guillarme, Davy

2013-03-22

358

Improved Quantification of Cerebral Hemodynamics Using Individualized Time Thresholds for Assessment of Peak Enhancement Parameters Derived from Dynamic Susceptibility Contrast Enhanced Magnetic Resonance Imaging  

PubMed Central

Purpose Assessment of cerebral ischemia often employs dynamic susceptibility contrast enhanced magnetic resonance imaging (DSC-MRI) with evaluation of various peak enhancement time parameters. All of these parameters use a single time threshold to judge the maximum tolerable peak enhancement delay that is supposed to reliably differentiate sufficient from critical perfusion. As the validity of this single threshold approach still remains unclear, in this study, (1) the definition of a threshold on an individual patient-basis, nevertheless (2) preserving the comparability of the data, was investigated. Methods The histogram of time-to-peak (TTP) values derived from DSC-MRI, the so-called TTP-distribution curve (TDC), was modeled using a double-Gaussian model in 61 patients without severe cerebrovascular disease. Particular model-based zf-scores were used to describe the arterial, parenchymal and venous bolus-transit phase as time intervals Ia,p,v. Their durations (delta Ia,p,v), were then considered as maximum TTP-delays of each phase. Results Mean-R2 for the model-fit was 0.967. Based on the generic zf-scores the proposed bolus transit phases could be differentiated. The Ip-interval reliably depicted the parenchymal bolus-transit phase with durations of 3.4 s–10.1 s (median?=?4.3s), where an increase with age was noted (?30 ms/year). Conclusion Individual threshold-adjustment seems rational since regular bolus-transit durations in brain parenchyma obtained from the TDC overlap considerably with recommended critical TTP-thresholds of 4 s–8 s. The parenchymal transit time derived from the proposed model may be utilized to individually correct TTP-thresholds, thereby potentially improving the detection of critical perfusion. PMID:25521121

Nasel, Christian; Kalcher, Klaudius; Boubela, Roland; Moser, Ewald

2014-01-01

359

A SNAP-tagged derivative of HIV-1--a versatile tool to study virus-cell interactions.  

PubMed

Fluorescently labeled human immunodeficiency virus (HIV) derivatives, combined with the use of advanced fluorescence microscopy techniques, allow the direct visualization of dynamic events and individual steps in the viral life cycle. HIV proteins tagged with fluorescent proteins (FPs) have been successfully used for live-cell imaging analyses of HIV-cell interactions. However, FPs display limitations with respect to their physicochemical properties, and their maturation kinetics. Furthermore, several independent FP-tagged constructs have to be cloned and characterized in order to obtain spectral variations suitable for multi-color imaging setups. In contrast, the so-called SNAP-tag represents a genetically encoded non-fluorescent tag which mediates specific covalent coupling to fluorescent substrate molecules in a self-labeling reaction. Fusion of the SNAP-tag to the protein of interest allows specific labeling of the fusion protein with a variety of synthetic dyes, thereby offering enhanced flexibility for fluorescence imaging approaches.Here we describe the construction and characterization of the HIV derivative HIV(SNAP), which carries the SNAP-tag as an additional domain within the viral structural polyprotein Gag. Introduction of the tag close to the C-terminus of the matrix domain of Gag did not interfere with particle assembly, release or proteolytic virus maturation. The modified virions were infectious and could be propagated in tissue culture, albeit with reduced replication capacity. Insertion of the SNAP domain within Gag allowed specific staining of the viral polyprotein in the context of virus producing cells using a SNAP reactive dye as well as the visualization of individual virions and viral budding sites by stochastic optical reconstruction microscopy. Thus, HIV(SNAP) represents a versatile tool which expands the possibilities for the analysis of HIV-cell interactions using live cell imaging and sub-diffraction fluorescence microscopy. PMID:21799764

Eckhardt, Manon; Anders, Maria; Muranyi, Walter; Heilemann, Mike; Krijnse-Locker, Jacomine; Müller, Barbara

2011-01-01

360

Multi-cellular interactions sustain long-term contractility of human pluripotent stem cell-derived cardiomyocytes  

PubMed Central

Therapeutic delivery of cardiomyocytes derived from human pluripotent stem cells (hPSC-CMs) represents a novel clinical approach to regenerate the injured myocardium. However, poor survival and contractility of these cells are a significant bottleneck to their clinical use. To better understand the role of cell-cell communication in enhancing the phenotype and contractile properties of hPSC-CMs, we developed a three-dimensional (3D) hydrogel composed of hPSC-CMs, human pluripotent stem cell-derived endothelial cells (hPSC-ECs), and/or human amniotic mesenchymal stem cells (hAMSCs). The objective of this study was to examine the role of multi-cellular interactions among hPSC-ECs and hAMSCs on the survival and long-term contractile phenotype of hPSC-CMs in a 3D hydrogel. Quantification of spontaneous contractility of hPSC-CMs in tri-culture demonstrated a 6-fold increase in the area of contractile motion after 6 weeks with characteristic rhythmic contraction frequency, when compared to hPSC-CMs alone (P < 0.05). This finding was supported by a statistically significant increase in cardiac troponin T protein expression in the tri-culture hydrogel construct at 6 weeks, when compared to hPSC-CMs alone (P < 0.001). The sustained hPSC-CM survival and contractility in tri-culture was associated with a significant upregulation in the gene expression of L-type Ca2+ ion channel, Cav1.2, and the inward-rectifier potassium channel, Kir2.1 (P < 0.05), suggesting a role of ion channels in mediating these processes. These findings demonstrate that multi-cellular interactions modulate hPSC-CM phenotype, function, and survival, and they will have important implications in engineering cardiac tissues for treatment of cardiovascular diseases. PMID:25628783

Burridge, Paul W; Metzler, Scott A; Nakayama, Karina H; Abilez, Oscar J; Simmons, Chelsey S; Bruce, Marc A; Matsuura, Yuka; Kim, Paul; Wu, Joseph C; Butte, Manish; Huang, Ngan F; Yang, Phillip C

2014-01-01

361

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

362

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

363

Human umbilical cord blood-derived mesenchymal stromal cells display a novel interaction between P-selectin and galectin-1.  

PubMed

Human multipotent mesenchymal stromal/stem cells (MSCs) have been shown to exert immunomodulatory properties that have great potential in therapies for various inflammatory and autoimmune disorders. However, intravenous delivery of these cells is followed by massive cell entrapment in the lungs and insufficient homing to target tissues or organs. In targeting to tissues, MSCs and other therapeutic cells employ similar mechanisms as leucocytes, including a cascade of rolling and adhesion steps mediated by selectins, integrins and their ligands. However, the mechanisms of MSCs homing are not well understood. We discovered that P-selectin (CD62P) binds to umbilical cord blood (UCB)-derived MSCs independently of the previously known sialyl Lewis x (sLex)-containing ligands such as P-selectin glycoprotein ligand-1 (PSGL-1, CD162). By biochemical assays, we identified galectin-1 as a novel ligand for P-selectin. Galectin-1 has previously been shown to be a key mediator of the immunosuppressive effects of human MSCs. We conclude that this novel interaction is likely to play a major role in the immunomodulatory targeting of human UCB-derived MSCs. PMID:24684681

Suila, H; Hirvonen, T; Kotovuori, A; Ritamo, I; Kerkelä, E; Anderson, H; Natunen, S; Tuimala, J; Laitinen, S; Nystedt, J; Räbinä, J; Valmu, L

2014-07-01

364

Improving homology modeling of G-protein coupled receptors through multiple-template derived conserved inter-residue interactions.  

PubMed

Evidenced by the three-rounds of G-protein coupled receptors (GPCR) Dock competitions, improving homology modeling methods of helical transmembrane proteins including the GPCRs, based on templates of low sequence identity, remains an eminent challenge. Current approaches addressing this challenge adopt the philosophy of "modeling first, refinement next". In the present work, we developed an alternative modeling approach through the novel application of available multiple templates. First, conserved inter-residue interactions are derived from each additional template through conservation analysis of each template-target pairwise alignment. Then, these interactions are converted into distance restraints and incorporated in the homology modeling process. This approach was applied to modeling of the human ?2 adrenergic receptor using the bovin rhodopsin and the human protease-activated receptor 1 as templates and improved model quality was demonstrated compared to the homology model generated by standard single-template and multiple-template methods. This method of "refined restraints first, modeling next", provides a fast and complementary way to the current modeling approaches. It allows rational identification and implementation of additional conserved distance restraints extracted from multiple templates and/or experimental data, and has the potential to be applicable to modeling of all helical transmembrane proteins. PMID:25503850

Chaudhari, Rajan; Heim, Andrew J; Li, Zhijun

2015-05-01

365

Interactions and hybrid complex formation of anionic algal polysaccharides with a cationic glycine betaine-derived surfactant.  

PubMed

The interaction between anionic algal polysaccharides ((?)-, (?)-, (?)-carrageenans, alginate and ulvan) and a cationic glycine betaine (GB) amide surfactant possessing a C18:1 alkyl chain has been studied using isothermal titration calorimetry (ITC), zeta-potential measurements, dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), and surface tension measurements. It was observed that this cationic surfactant derived from renewable raw materials induced cooperative binding with the anionic polymers at critical aggregation concentration (CAC) and the CAC values are significantly lower than the corresponding critical micelle concentration (CMC) for the surfactant. The CMC of cationic GB surfactant was obtained at higher surfactant concentration in polysaccharide solution than in pure water. More interestingly, the presence of original polysaccharide/surfactant hybrid complexes formed above the CMC value was evidenced from (?)-carrageenan by microscopy (TEM and AFM). Preliminary investigations of the structure of these complexes revealed the existence of surfactant nanoparticles surrounded with polysaccharide matrix, probably resulting from electrostatic attraction. In addition, ITC measurements clearly showed that the interactions of the ?-carrageenan was stronger than for other polysaccharides ((?)-, (?)-carrageenans, alginate and ulvan). These results may have important impact on the use of the GB amide surfactant in formulations based on algal polysaccharides for several applications such as in food, cosmetics, and detergency fields. PMID:25659719

Covis, Rudy; Vives, Thomas; Gaillard, Cédric; Benoit, Maud; Benvegnu, Thierry

2015-05-01

366

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

367

Interaction of artesunate with ?-cyclodextrin: Characterization, thermodynamic parameters, molecular modeling, effect of PEG on complexation and antimalarial activity  

PubMed Central

Inclusion of artesunate in the cavity of ?-cyclodextrin (?-CD) as well as its methyl and hydroxypropyl derivatives was investigated experimentally and by molecular modeling studies. The effect of PEG on the inclusion was also studied. A 1:1 stoichiometry was indicated by phase-solubility studies both in the presence and absence of PEG and suggested by the mass spectrometry. The mode of inclusion was supported by 2D NMR and results were further verified by docking studies utilizing Fast Rigid Exhaustive Docking acronym. The thermodynamic parameters were determined for both binary and ternary systems using solution calorimetry and were found to be best for the methyl-?-cyclodextrin (Me-?-CD) system. However, the presence of PEG improves the complexation ability as evident from elevation in the numerical value of the stability constant (K). Solubility and dissolution profile of binary complex is enhanced in the presence of PEG, which is approximately at par with drug Me-?-CD complexes. In vivo studies showed 100% survivability in artesunate–Me-?-CD complexes.

Chadha, Renu; Gupta, Sushma; Shukla, Geeta; Jain, D.V.S.; Pissurlenkar, Raghuvir R.S.; Coutinho, Evans C.

2011-01-01

368

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 $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

369

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

370

Multi-spectroscopic analysis and molecular modeling on the interaction of curcumin and its derivatives with human serum albumin: a comparative study.  

PubMed

The comparative study about the interaction between curcumin and its derivatives (demothxycurcumin and bisdeoxycurcumin) with human serum albumin (HSA) has been carried out using multi-spectroscopic analysis and molecular modeling method. The characteristic of fluorescence quenching and the thermodynamic parameters have been studied by state emission fluorescence experiments under different temperatures with an interval of 6 K. Curcumin shows largest quenching constant and bisdeoxycurcumin shows the smallest at the temperature of 298 K. However, the quenching constant of curcumin drops quickly with the increase of temperature. Demothxycurcumin gives the largest quenching efficiency at the temperature of 310 K. An average distance of 6.7 nm for energy transfer has been determined based on förster resonance energy theory (FRET). The site competitive replacement experiments illustrate three compounds mainly binding on site I (Subdomain IIA) of the protein, and show tendency of binding on site II (Subdomain IIIA) with the removing of methoxyl groups. Circular dichroism spectra and Fourier transform infrared spectroscopy (FTIR) have been used to investigate the influence on protein secondary structure. Content of the ?-helix increases at low concentrations of the compounds, while unfolding occurs at high concentrations. Docking simulation reveals possible mechanism for different quenching behavior and binding sites preferred by three compounds. The binding modes have effectively supported the conclusion of the experiments. PMID:24491667

Ge, Yu-Shu; Jin, Cheng; Song, Zhe; Zhang, Jia-Qi; Jiang, Feng-Lei; Liu, Yi

2014-04-24

371

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

372

Diffusion and Sedimentation Interaction Parameters for Measuring the Second Virial Coefficient and Their Utility as Predictors of Protein Aggregation  

PubMed Central

The concentration-dependence of the diffusion and sedimentation coefficients (kD and ks, respectively) of a protein can be used to determine the second virial coefficient (B2), a parameter valuable in predicting protein-protein interactions. Accurate measurement of B2 under physiologically and pharmaceutically relevant conditions, however, requires independent measurement of kD and ks via orthogonal techniques. We demonstrate this by utilizing sedimentation velocity (SV) and dynamic light scattering (DLS) to analyze solutions of hen-egg white lysozyme (HEWL) and a monoclonal antibody (mAb1) in different salt solutions. The accuracy of the SV-DLS method was established by comparing measured and literature B2 values for HEWL. In contrast to the assumptions necessary for determining kD and ks via SV alone, kD and ks were of comparable magnitudes, and solution conditions were noted for both HEWL and mAb1 under which 1), kD and ks assumed opposite signs; and 2), kD ? ks. Further, we demonstrate the utility of kD and ks as qualitative predictors of protein aggregation through agitation and accelerated stability studies. Aggregation of mAb1 correlated well with B2, kD, and ks, thus establishing the potential for kD to serve as a high-throughput predictor of protein aggregation. PMID:20959107

Saluja, Atul; Fesinmeyer, R. Matthew; Hogan, Sabine; Brems, David N.; Gokarn, Yatin R.

2010-01-01

373

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

374

Change of the sign of superconducting intraband order parameters induced by interband pair hopping interaction in iron-based high-temperature superconductors  

NASA Astrophysics Data System (ADS)

Iron based superconductors are characterized by the {{s}+/- } gap symmetry, where the gap changes its sign between pockets of the Fermi surface. We discuss another sign change mechanism of the superconducting order parameter (OP)—the interband Cooper pairs hopping interaction. In the minimal two-orbital model of iron based superconductors we show that this interaction can lead to a change of the sign of the intraband superconducting OP regardless of its symmetry.

Ptok, Andrzej; Crivelli, Dawid; Jerzy Kapcia, Konrad

2015-04-01

375

Interaction impedance from the equivalent circuit parameters of a dielectric-loaded helical slow-wave structure of a traveling-wave tube  

Microsoft Academic Search

The interaction impedance of the dielectric-loaded helical slow-wave structure (SWS) of a traveling-wave tube (TWT), with or without a metal envelope, has been found by integrating the Poynting vector across the structure cross section. A simple empirical relation is then suggested to predict the value of the interaction impedance from the knowledge of the equivalent-circuit parameters of the structure without

V. P. Singh; K. V. R. Murty; B. N. Basu

1988-01-01

376

Interaction impedance from the equivalent circuit parameters of a dielectric-loaded helical slow-wave structure of a traveling-wave tube  

NASA Astrophysics Data System (ADS)

The interaction impedance of the dielectric-loaded helical slow-wave structure (SWS) of a traveling-wave tube (TWT), with or without a metal envelope, has been found by integrating the Poynting vector across the structure cross section. A simple empirical relation is then suggested to predict the value of the interaction impedance from the knowledge of the equivalent-circuit parameters of the structure without requiring the complex integration of the Poynting vector.

Singh, V. P.; Murty, K. V. R.; Basu, B. N.

1988-04-01

377

Interaction of PiB-Derivative Metal Complexes with Beta-Amyloid Peptides: Selective Recognition of the Aggregated Forms.  

PubMed

Metal complexes are increasingly explored as imaging probes in amyloid peptide related pathologies. We report the first detailed study on the mechanism of interaction between a metal complex and both the monomer and the aggregated form of A?1-40 peptide. We have studied lanthanide(III) chelates of two PiB-derivative ligands (PiB=Pittsburgh compound B), L(1) and L(2) , differing in the length of the spacer between the metal-complexing DO3A macrocycle (DO3A= 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) and the peptide-recognition PiB moiety. Surface plasmon resonance (SPR) and saturation transfer difference (STD) NMR spectroscopy revealed that they both bind to aggregated A?1-40 (KD =67-160??M), primarily through the benzothiazole unit. HSQC?NMR spectroscopy on the (15) N-labeled, monomer A?1-40 peptide indicates nonsignificant interaction with monomeric A?. Time-dependent circular dichroism (CD), dynamic light scattering (DLS), and TEM investigations of the secondary structure and of the aggregation of A?1-40 in the presence of increasing amounts of the metal complexes provide coherent data showing that, despite their structural similarity, the two complexes affect A? fibril formation distinctly. Whereas GdL(1) , at higher concentrations, stabilizes ?-sheets, GdL(2) prevents aggregation by promoting ?-helical structures. These results give insight into the behavior of amyloid-targeted metal complexes in general and contribute to a more rational design of metal-based diagnostic and therapeutic agents for amyloid- associated pathologies. PMID:25712142

Martins, André F; Dias, David M; Morfin, Jean-François; Lacerda, Sara; Laurents, Douglas V; Tóth, Éva; Geraldes, Carlos F G C

2015-03-27

378

A Process-based, Climate-Sensitive Model to Derive Methane Emissions from Natural Wetlands: Application to 5 Wetland Sites, Sensitivity to Model Parameters and Climate  

NASA Technical Reports Server (NTRS)

Methane emissions from natural wetlands constitutes the largest methane source at present and depends highly on the climate. In order to investigate the response of methane emissions from natural wetlands to climate variations, a 1-dimensional process-based climate-sensitive model to derive methane emissions from natural wetlands is developed. In the model the processes leading to methane emission are simulated within a 1-dimensional soil column and the three different transport mechanisms diffusion, plant-mediated transport and ebullition are modeled explicitly. The model forcing consists of daily values of soil temperature, water table and Net Primary Productivity, and at permafrost sites the thaw depth is included. The methane model is tested using observational data obtained at 5 wetland sites located in North America, Europe and Central America, representing a large variety of environmental conditions. It can be shown that in most cases seasonal variations in methane emissions can be explained by the combined effect of changes in soil temperature and the position of the water table. Our results also show that a process-based approach is needed, because there is no simple relationship between these controlling factors and methane emissions that applies to a variety of wetland sites. The sensitivity of the model to the choice of key model parameters is tested and further sensitivity tests are performed to demonstrate how methane emissions from wetlands respond to climate variations.

Walter, Bernadette P.; Heimann, Martin

1999-01-01

379

Tables and graphs of photon-interaction cross sections from 0. 1 keV to 100 MeV derived from the LLL evaluated-nuclear-data library  

SciTech Connect

Energy-dependent evaluated photon interaction cross sections and related parameters are presented for elements H through Cf(Z = 1 to 98). Data are given over the energy range from 0.1 keV to 100 MeV. The related parameters include form factors and average energy deposits per collision (with and without fluorescence). Fluorescence information is given for all atomic shells that can emit a photon with a kinetic energy of 0.1 keV or more. In addition, the following macroscopic properties are given: total mean free path and energy deposit per centimeter. This information is derived from the Livermore Evaluated-Nuclear-Data Library (ENDL) as of October 1978.

Plechaty, E.F.; Cullen, D.E.; Howerton, R.J.

1981-11-11

380

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

381

New potential antitumoral fluorescent tetracyclic thieno[3,2- b]pyridine derivatives: interaction with DNA and nanosized liposomes  

NASA Astrophysics Data System (ADS)

Fluorescence properties of two new potential antitumoral tetracyclic thieno[3,2- b]pyridine derivatives were studied in solution and in liposomes of DPPC (dipalmitoyl phosphatidylcholine), egg lecithin (phosphatidylcholine from egg yolk; Egg-PC) and DODAB (dioctadecyldimethylammonium bromide). Compound 1, pyrido[2',3':3,2]thieno[4,5- d]pyrido[1,2- a]pyrimidin-6-one, exhibits reasonably high fluorescence quantum yields in all solvents studied (0.20 ? ?F ? 0.30), while for compound 2, 3-[( p-methoxyphenyl)ethynyl]pyrido[2',3':3,2]thieno[4,5- d]pyrido[1,2- a]pyrimidin-6-one, the values are much lower (0.01 ? ?F ? 0.05). The interaction of these compounds with salmon sperm DNA was studied using spectroscopic methods, allowing the determination of intrinsic binding constants, K i = (8.7 ± 0.9) × 103 M-1 for compound 1 and K i = (5.9 ± 0.6) × 103 M-1 for 2, and binding site sizes of n = 11 ± 3 and n = 7 ± 2 base pairs, respectively. Compound 2 is the most intercalative compound in salmon sperm DNA (35%), while for compound 1 only 11% of the molecules are intercalated. Studies of incorporation of both compounds in liposomes of DPPC, Egg-PC and DODAB revealed that compound 2 is mainly located in the hydrophobic region of the lipid bilayer, while compound 1 prefers a hydrated and fluid environment.

Castanheira, Elisabete Ms; Carvalho, Maria Solange D.; Rodrigues, Ana Rita O.; Calhelha, Ricardo C.; Queiroz, Maria-João Rp

2011-05-01

382

JOURNAL DE PHYSIQUE Colloque C6, supplkment au no 12, Tome 37, Dkcembre 1976, page C6-651 HYPERFINE INTERACTION PARAMETERS AT IODINE  

E-print Network

INTERACTION PARAMETERS AT IODINE IN VANADIUM (11) IODIDE FROM lZ9IMOSSBAUER SPECTROSCOPY J. M. FRIEDT and J. P ionsvanadiumprochesvoisins. Abstract. -The charge and spin densities at iodine in vanadium diiodide are obtained from the 1 2 at the iodine site were deduced from a careful computer analysis of the experimental data (Table I). In agree

Paris-Sud XI, Université de

383

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

384

Magnetic interactions and covalency effects in mainly ionic compounds  

Microsoft Academic Search

The effects of covalency on the magnetic interactions like exchange, superexchange and hyperfine interactions are discussed for mainly ionic compounds. Relations are derived using a nearest neighbor cluster model relating the exchange interactions and transferred hyperfine interactions to covalency parameters and to the bond angle. With the aid of some examples we show how information about the superexchange interactions can

G. A. Sawatzky; W. Geertsma; C. Haas

1976-01-01

385

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

386

Comparison of anomalies and trends of OLR as observed by CERES and computed from geophysical parameters derived from analysis of AIRS/AMSU data  

NASA Astrophysics Data System (ADS)

Anomalies and trends of OLR serve as important indicators of climate change. Several satellite based instruments currently provide information related to OLR. CERES, on board the EOS Aqua and Terra satellites, contains broad band radiometers that measure total flux and short-wave flux, from which OLR is determined. AIRS is a high spectral resolution IR sounder on EOS Aqua that measures IR radiances covering most of the spectral interval 650 cm-1 to 2670 cm-1. These observations enable the determination of detailed information about atmospheric temperature, moisture, and ozone profiles, as well as surface skin temperatures and cloud parameters. The AIRS OLR product is the total flux over the spectral interval 2 cm-1 to2750 cm-1 computed for the surface and atmospheric state determined from AIRS observations. We compared spatial anomalies and trends of OLR, over the seven year period September 2002 through August 2009, as observed by CERES and computed using Version 5 AIRS products. These two sets of OLR anomalies and trends, obtained in very different ways, agree with each other almost perfectly in essentially every detail. This important finding shows that a very stable high spectral infra-red sounder such as AIRS corroborates the anomalies and trends of OLR obtained from CERES. More significantly, anomalies and trends of the individual geophysical parameters derived from AIRS explain the detailed causes of the anomalies and trends of CERES OLR. Both sets of results show that global mean OLR has been decreasing at a rate of 0.12 W/m2/yr over the seven year time period under study. Both also confirm that the primary cause of this is due to changes in the tropics, in which OLR has been decreasing at a rate of 0.27 W/m2/yr. AIRS products show that the decrease of tropical OLR is a result of increasing tropical atmospheric water vapor and cloud cover over the time period studied, which in turn is responding to a very strong El Nino/ La Nina cycle. Equatorial ocean temperatures between 160E and 120W cooled considerably during this time period, with corresponding local decreases in mid-tropospheric humidity and cloud cover, resulting in increases in local OLR. This was more than compensated by substantial increases in water vapor and cloud cover elsewhere in the tropics, resulting in a net decrease in tropical OLR.

Susskind, J.; Molnar, G. I.

2009-12-01

387

Comparison of Anomalies and Trends of OLR as Observed by CERES and Computed from Geophysical Parameters Derived from Analysis of AIRS/AMSU Data  

NASA Technical Reports Server (NTRS)

Anomalies and trends of outgoing longwave radiation (OLR) serve as important indicators of climate change. Several satellite based instruments currently provide information related to OLR. CERES, on board the EOS Aqua and Terra satellites, contains broad band radiometers that measure total flux and short-wave flux, from which OLR is determined. AIRS is a high spectral resolution IR sounder on EOS Aqua that measures IR radiances covering most of the spectral interval 650 cm-1 to 2670 cm-1. These observations enable the determination of detailed information about atmospheric temperature, moisture, and ozone profiles, as well as surface skin temperatures and cloud parameters. The AIRS OLR product is the total flux over the spectral interval 2 cm-1 to2750 cm-1 computed for the surface and atmospheric state determined from AIRS observations. We compared spatial anomalies and trends of OLR, over the seven year period September 2002 through August 2009, as observed by CERES and computed using Version 5 AIRS products. These two sets of OLR anomalies and trends, obtained in very different ways, agree with each other almost perfectly in essentially every detail. This important finding shows that a very stable high spectral infra-red sounder such as AIRS corroborates the anomalies and trends of OLR obtained from CERES. More significantly, anomalies and trends of the individual geophysical parameters derived from AIRS explain the detailed causes of the anomalies and trends of CERES OLR. Both sets of results show that global mean OLR has been decreasing at a rate of 0.12 W/m2/yr over the seven year time period under study. Both also confirm that the primary cause of this is due to changes in the tropics, in which OLR has been decreasing at a rate of 0.27 W/m2/yr. AIRS products show that the decrease of tropical OLR is a result of increasing tropical atmospheric water vapor and cloud cover over the time period studied, which in turn is responding to a very strong E1 Nino/ La Nina cycle. Equatorial ocean temperatures between 160E and 120W cooled considerably during this time period, with corresponding local decreases in mid-tropospheric humidity and cloud cover, resulting in increases in local OLR. This was more than compensated by substantial increases in water vapor and cloud cover elsewhere in the tropics, resulting in a net decrease in tropical OLR.

Susskind, Joel; Molnar, Gyula I.

2009-01-01

388

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

389

Simulation of Seismicity in the Japanese Islands with an Interacting Fault System Model Derived from Geodetic Data  

NASA Astrophysics Data System (ADS)

Abundant geodetic data enabled us to estimate fault deficit rates in and around the Japanese Islands. Hashimoto and Jackson (1993) first estimated fault slip deficit rates using triangulation and trilateration data with a block and fault model. Here we present results of a simulation of seismicity using this fault model, in order to investigate correlations between interplate and intraplate events, long range correlations of seismicity, and discrepancies in strain rates derived from geodesy, geology and historical seismicity. Hashimoto and Jackson's original model has 104 faults. However, the original fault sizes are too large to accommodate small earthquakes, so we divide each modeled fault into 5 x 5 elements in order to be able to generate earthquakes as small as M5. In total there are 2600 elements. We assume stress accumulates according to the estimated slip deficit rates. In our model we deal with only ? CFF, among the stress components that promote rupture consistent with the estimated slip deficit rates. Interaction between fault elements is represented by ? CFF. When stress reaches a threshold level, accumulated stress is released by forward slip and redistributed to surrounding faults according to their geometrical relationship. The thresholds for rupture are assumed to be 0.5 MPa for interplate faults and 2.0 MPa for inland faults, respectively, and are uniform on each fault. These values are consistent with the typically observed slips of earthquakes for the model faults with their original size. If redistribution of stress causes the next rupture, the same process repeats. In this simulation, the time step is 1 year. Due to the computer limitations, we could calculate only for 5,000 years. The rigidity is 40GPa and friction coefficient varied from 0 to 0.7. Results of the simulation show that large events in which entire faults rupture rarely occur. This suggests that strain rates from geology or historical seismicity might be underestimated. However, Gutenberg-Richter law does not hold in this model, which suggests that we need heterogeneity in the rupture threshold or the size of elements on a fault plane. Seismicity of the model is much higher than the rate of earthquakes in Japan. This may be attributed to the use of slip deficit rates derived from geodetic data and suggests that geodetic strain is not entirely released by earthquakes. Correlation between interplate and inland events is not clear, however migration of events such as those observed along the Nankai trough can be seen in this simulation.

Hashimoto, M.

2001-12-01

390

Development and validation of an integrated diagnostic algorithm derived from parameters monitored in implantable devices for identifying patients at risk for heart failure hospitalization in an ambulatory setting  

PubMed Central

Background We developed and validated a heart failure (HF) risk score combining daily measurements of multiple device-derived parameters. Methods Heart failure patients from clinical studies with implantable devices were used to form two separate data sets. Daily HF scores were estimated by combining changes in intra-thoracic impedance, atrial fibrillation (AF) burden, rapid rate during AF, %CRT pacing, ventricular tachycardia, night heart rate, heart rate variability, and activity using a Bayesian model. Simulated monthly follow-ups consisted of looking back at the maximum daily HF risk score in the preceding 30 days, categorizing the evaluation as high, medium, or low risk, and evaluating the occurrence of HF hospitalizations in the next 30 days. We used an Anderson–Gill model to compare survival free from HF events in the next 30 days based on risk groups. Results The development data set consisted of 921 patients with 9790 patient-months of data and 91 months with HF hospitalizations. The validation data set consisted of 1310 patients with 10 655 patient-months of data and 163 months with HF hospitalizations. In the validation data set, 10% of monthly evaluations in 34% of the patients were in the high-risk group. Monthly diagnostic evaluations in the high-risk group were 10 times (adjusted HR: 10.0; 95% CI: 6.4–15.7, P < 0.001) more likely to have an HF hospitalization (event rate of 6.8%) in the next 30 days compared with monthly evaluations in the low-risk group (event rate of 0.6%). Conclusion An HF score based on implantable device diagnostics can identify increased risk for HF hospitalization in the next 30 days. PMID:23513212

Cowie, Martin R.; Sarkar, Shantanu; Koehler, Jodi; Whellan, David J.; Crossley, George H.; Tang, Wai Hong Wilson; Abraham, William T.; Sharma, Vinod; Santini, Massimo

2013-01-01

391

Derivation of coupled Maxwell-Schroedinger equations describing matter-laser interaction from first principles of quantum electrodynamics  

SciTech Connect

We study the general problem of matter-laser interaction within the framework of nonrelativistic quantum electrodynamics, with particular emphasis on strong laser field effects. Consequently, we formulate a well-defined approximation leading in a straightforward manner toward the conventional semiclassical mode of description. Namely, we arrive naturally to two coupled equations of motion: (i) the Schroedinger equation which governs the quantum dynamics of an atomic system driven by classically described radiation field (composed of an incoming laser pulse plus radiation emitted from the atom), and (ii) the classical Maxwell wave equation which describes the emission of radiation from the mentioned atomic source. Employing the formalism of adiabatic Floquet theory, we derive a simple criterion of validity of the just described semiclassical approach. It shows that the semiclassical treatment is justified in most situations. On the other hand, it turns out that the semiclassical approximation breaks down completely in certain special but realistic cases, regardless of the fact that the incoming laser pulse contains a huge number of photons. Under such special circumstances, we anticipate new effects arising due to the quantized nature of the radiation field, to be observable, for example, in harmonic generation spectra. Our considerations are illustrated more explicitly using a simple model of a two-level atom strongly driven by a laser. The quantum dynamics of this model problem is resolved within the framework of quantum electrodynamics while adopting well-defined and physically justifiable approximations. As an outcome, analytic formulas are found serving as a quantitative criterion of (non)applicability of the semiclassical approach and demonstrating the breakdown of semiclassical theory under well-defined conditions. An illustrative numerical calculation is provided.

Sindelka, Milan [Department of Physics and Minerva Center for Non-Linear Physics of Complex Systems, Technion - Israel Institute of Technology, Haifa IL-32000 (Israel)

2010-03-15

392

Derivation of parameters necessary for the evaluation of performance of sites for deep geological repositories with particular reference to bedded salt, Livermore, California. Volume I. Main text  

Microsoft Academic Search

A survey of parameters to be considered in the evaluation of sites for deep geologic nuclear waste repositories is presented. As yet, no comprehensive site selection procedure or performance evaluation approach has been adopted. A basis is provided for the development of parameters by discussing both site selection and performance evaluation. Three major groups of parameters are considered in this

J. P. Ashby; G. E. Rawlings; C. A. Soto; D. F. Wood; D. W. Chorley

1979-01-01

393

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

394

The effect of specific solvent-solute interactions on complexation of alkali-metal cations by a lower-rim calix[4]arene amide derivative.  

PubMed

Complexation of alkali-metal cations with calix[4]arene secondary-amide derivative, 5,11,17,23-tetra(tert-butyl)-25,26,27,28-tetra(N-hexylcarbamoylmethoxy)calix[4]arene (L), in benzonitrile (PhCN) and methanol (MeOH) was studied by means of microcalorimetry, UV and NMR spectroscopies, and in the solid state by X-ray crystallography. The inclusion of solvent molecules (including acetonitrile, MeCN) in the calixarene hydrophobic cavity was also investigated. The classical molecular dynamics (MD) simulations of the systems studied were carried out. By combining the results obtained using the mentioned experimental and computational techniques, an attempt was made to get an as detailed insight into the complexation reactions as possible. The thermodynamic parameters, that is, equilibrium constants, reaction Gibbs energies, enthalpies, and entropies, of the investigated processes were determined and discussed. The stability constants of the 1:1 (metal:ligand) complexes measured by different methods were in very good agreement. Solution Gibbs energies of the ligand and its complexes with Na(+) and K(+) in methanol and acetonitrile were determined. It was established that from the thermodynamic point of view, apart from cation solvation, the most important reason for the huge difference in the stability of these complexes in the two solvents lay in the fact that the transfer of complex species from MeOH to MeCN was quite favorable. That could be at least partly explained by a more exergonic inclusion of the solvent molecule in the complexed calixarene cone in MeCN as compared to MeOH, which was supported by MD simulations. Molecular and crystal structures of the lithium cation complex of L with the benzonitrile molecule bound in the hydrophobic calixarene cavity were determined by single-crystal X-ray diffraction. As far as we are aware, for the first time the alkali-metal cation was found to be coordinated by the solvent nitrile group in a calixarene adduct. According to the results of MD simulations, the probability of such orientation of the benzonitrile molecule included in the ligand cone was by far the largest in the case of LiL(+) complex. Because of the favorable PhCN-Li(+) interaction, L was proven to have the highest affinity toward the lithium ion in benzonitrile, which was not the case in the other solvents examined (in acetonitrile, sodium complex was the most stable, whereas in methanol, complexation of lithium was not even observed). That could serve as a remarkable example showing the importance of specific solvent-solute interactions in determining the equilibrium in solution. PMID:24144364

Horvat, Gordan; Stilinovi?, Vladimir; Kaitner, Branko; Frkanec, Leo; Tomiši?, Vladislav

2013-11-01

395

Peptides derived from human galectin-3 N-terminal tail interact with its carbohydrate recognition domain in a phosphorylation-dependent manner  

SciTech Connect

Highlights: •Galectin-3 is composed of a carbohydrate recognition domain and an N-terminal tail. •Synthetic peptides derived from the tail are shown to interact with the CRD. •This interaction is modulated by Ser- and Tyr-phosphorylation of the peptides. -- Abstract: Galectin-3 (Gal-3) is a multi-functional effector protein that functions in the cytoplasm and the nucleus, as well as extracellularly following non-classical secretion. Structurally, Gal-3 is unique among galectins with its carbohydrate recognition domain (CRD) attached to a rather long N-terminal tail composed mostly of collagen-like repeats (nine in the human protein) and terminating in a short non-collagenous terminal peptide sequence unique in this lectin family and not yet fully explored. Although several Ser and Tyr sites within the N-terminal tail can be phosphorylated, the physiological significance of this post-translational modification remains unclear. Here, we used a series of synthetic (phospho)peptides derived from the tail to assess phosphorylation-mediated interactions with {sup 15}N-labeled Gal-3 CRD. HSQC-derived chemical shift perturbations revealed selective interactions at the backface of the CRD that were attenuated by phosphorylation of Tyr 107 and Tyr 118, while phosphorylation of Ser 6 and Ser 12 was essential. Controls with sequence scrambling underscored inherent specificity. Our studies shed light on how phosphorylation of the N-terminal tail may impact on Gal-3 function and prompt further studies using phosphorylated full-length protein.

Berbís, M. Álvaro [Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid (Spain)] [Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid (Spain); André, Sabine [Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians University, 80539 Munich (Germany)] [Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians University, 80539 Munich (Germany); Cañada, F. Javier [Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid (Spain)] [Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid (Spain); Pipkorn, Rüdiger [Central Peptide Synthesis Unit, German Cancer Research Center, 69120 Heidelberg (Germany)] [Central Peptide Synthesis Unit, German Cancer Research Center, 69120 Heidelberg (Germany); Ippel, Hans [Department of Biochemistry, CARIM, University of Maastricht, Maastricht (Netherlands) [Department of Biochemistry, CARIM, University of Maastricht, Maastricht (Netherlands); Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Mayo, Kevin H. [Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455 (United States)] [Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Kübler, Dieter [Biomolecular Interactions, German Cancer Research Center, 69120 Heidelberg (Germany)] [Biomolecular Interactions, German Cancer Research Center, 69120 Heidelberg (Germany); Gabius, Hans-Joachim [Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians University, 80539 Munich (Germany)] [Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians University, 80539 Munich (Germany); Jiménez-Barbero, Jesús, E-mail: jjbarbero@cib.csic.es [Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid (Spain)] [Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid (Spain)

2014-01-03

396

Enthalpic homogeneous pair interaction coefficients of L-alpha-amino acids as a hydrophobicity parameter of amino acid side chains.  

PubMed

Enthalpies of dilution of aqueous solutions of L-alpha-cysteine, L-alpha-histidine, L-alpha-asparagine, L-alpha-glutamine, L-alpha-arginine, L-alpha-tryptophan, and L-alpha-glutamic acid in water at a temperature of 298.15 K have been measured. The values of dilution enthaply were used to determine enthalpic homogeneous pair interaction coefficients which characterize the interactions between zwitterions of the examined L-alpha-amino acids in water. Approachable literature data of hydrophobic scales have been analyzed to obtain average values. The obtained values of enthalpic pair interaction coefficients have been put together with an average hydrophobic scale. PMID:12022833

Palecz, Bartlomiej

2002-05-29

397

Vortex chains due to nonpairwise interactions and field-induced phase transitions between states with different broken symmetry in superconductors with competing order parameters  

NASA Astrophysics Data System (ADS)

We study superconductors with two order components and phase separation driven by intercomponent density-density interaction, focusing on the phase where only one condensate has nonzero ground-state density and a competing order parameter exists only in vortex cores. We demonstrate there that multibody intervortex interactions can be strongly nonpairwise, leading to some unusual vortex patterns in an external field, such as vortex pairs and vortex chains. We demonstrate that in an external magnetic field such a system undergoes a field-driven phase transition from (broken) U (1 ) to (broken) U (1 )×U (1 ) symmetries when a subdominant order parameter in the vortex cores acquires global coherence. Observation of these characteristic ordering patterns in surface probes may signal the presence of a subdominant condensate in the vortex core.

Garaud, Julien; Babaev, Egor

2015-01-01

398

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

399

Interaction of inflammatory and anti-inflammatory responses in microglia by Staphylococcus aureus-derived lipoteichoic acid  

SciTech Connect

We investigated the interaction between proinflammatory and inflammatory responses caused by Staphylococcus aureus-derived lipoteichoic acid (LTA) in primary cultured microglial cells and BV-2 microglia. LTA induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein levels increase in a concentration- and time-dependent manner. Meanwhile, LTA also increased nitric oxide (NO) and PGE{sub 2} production in microglia. Administration of TLR2 antagonist effectively inhibited LTA-induced NO, iNOS, and COX-2 expression. Moreover, treatment of cells with LTA caused a time-dependent activation of ERK, p38, JNK, as well as AKT. We also found that LTA-induced iNOS and COX-2 up-regulation were attenuated by p38, JNK, and PI3-kinase inhibitors. On the other hand, LTA-enhanced HO-1 expression was attenuated by p38 and PI3-kinase inhibitors. Treatment of cells with NF-?B and AP-1 inhibitors antagonized LTA-induced iNOS and COX-2 expression. However, only NF-?B inhibitors reduced LTA-induced HO-1 expression in microglia. Furthermore, stimulation of cells with LTA also activated I?B? phosphorylation, p65 phosphorylation at Ser{sup 536}, and c-Jun phosphorylation. Moreover, LTA-induced increases of ?B-DNA and AP-1-DNA binding activity were inhibited by p38, JNK, and PI3-kinase inhibitors. HO-1 activator CoPP IX dramatically reversed LTA-induced iNOS expression. Our results provided mechanisms linking LTA and inflammation/anti-inflammation, and indicated that LTA plays a regulatory role in microglia activation. - Highlights: • LTA causes an increase in iNOS, COX-2, and HO-1 expression in microglia. • LTA induces iNOS and COX-2 expression through TLR-2/NF-?B and AP-1 pathways. • HO-1 expression is regulated through p38, JNK, PI3K/AKT and AP-1 pathways. • Induced HO-1 reduces LTA-induced iNOS expression. • LTA plays a regulatory role on inflamma