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1

Understanding Interactions among Genetic Algorithm Parameters  

Microsoft Academic Search

Genetic algorithms (GAs) are multi-dimensional and stochastic search methods, involving complex in- teractions among their parameters. For last two decades, researchers have been trying to understand the mechanics of GA parameter interactions by using various techniques. The methods include careful 'func- tional' decomposition of parameter interactions, empirical studies, and Markov chain analysis. Although the complex knot of these interactions are

Kalyanmoy Deb; Samir Agrawal

1998-01-01

2

Inertial Parameters in the Interacting Boson Fermion Approximation.  

National Technical Information Service (NTIS)

The Hartree-Bose-Fermi and the adiabatic approximations are used to derive analytic formulas for the moment of inertia and the decoupling parameter of the interacting boson fermion approximation for deformed systems. These formulas are applied to the SU(3...

J. Dukelsky C. Lima

1986-01-01

3

Interactions between SH2 domains and tyrosine-phosphorylated platelet-derived growth factor beta-receptor sequences: analysis of kinetic parameters by a novel biosensor-based approach.  

PubMed Central

The interaction between SH2 domains and phosphotyrosine-containing sequences was examined by real-time measurements of kinetic parameters. The SH2 domains of the p85 subunit of the phosphatidylinositol 3-kinase as well as of other signaling molecules were expressed in bacteria as glutathione S-transferase fusion proteins. Phosphotyrosine-containing peptides, corresponding to two autophosphorylation sites on the human platelet-derived growth factor beta-receptor that are responsible for phosphatidylinositol 3-kinase binding, were synthesized and used as capturing molecules, immobilized on a biosensor surface. The association and dissociation rate constants for binding to both sites were determined for intact p85 and the recombinant SH2 domains. High association rates were found to be coupled to very fast dissociation rates for all interactions studied. A binding specificity was observed for the two SH2 domains of p85, with the N-terminal SH2 binding with high affinity to the Tyr-751 site but not to the Tyr-740 site, and the C-terminal SH2 interacting strongly with both sites. This approach should be generally applicable to the study of the specificity inherent in the assembly of signaling complexes by activated protein-tyrosine kinase receptors.

Panayotou, G; Gish, G; End, P; Truong, O; Gout, I; Dhand, R; Fry, M J; Hiles, I; Pawson, T; Waterfield, M D

1993-01-01

4

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

5

Satellite Data Derived Estimates of Erosion Parameters for Reentry Vehicles.  

National Technical Information Service (NTIS)

This study investigates the derivation of reentry-vehicle erosion parameter estimates based on the inference of rain rate and hydrometeor liquid water content from microwave imagery data from the Defense Meteorological Satellite Program (DMSP) sensors. Sp...

H. C. Huang J. S. Belfiore R. G. Isaacs

1991-01-01

6

Photon Interaction Parameters for Some Borate Glasses  

NASA Astrophysics Data System (ADS)

Some photon interaction parameters of dosimetric interest such as mass attenuation coefficients, effective atomic number, electron density and KERMA relative to air have been computed in the wide energy range from 1 keV to 100 GeV for some borate glasses viz. barium-lead borate, bismuth-borate, calcium-strontium borate, lead borate and zinc-borate glass. It has been observed that lead borate glass and barium-lead borate glass have maximum values of mass attenuation coefficient, effective atomic number and KERMA relative to air. Hence, these borate glasses are suitable as gamma ray shielding material, packing of radioactive sources etc.

Mann, Nisha; Kaur, Updesh; Singh, Tejbir; Sharma, J. K.; Singh, Parjit S.

2010-11-01

7

Ternary Interaction Parameters in Calphad Solution Models  

NASA Astrophysics Data System (ADS)

For random, diluted, multicomponent solutions, the excess chemical potentials can be expanded in power series of the composition, with coefficients that are pressure- and temperature-dependent. For a binary system, this approach is equivalent to using polynomial truncated expansions, such as the Redlich-Kister series for describing integral thermodynamic quantities. For ternary systems, an equivalent expansion of the excess chemical potentials clearly justifies the inclusion of ternary interaction parameters, which arise naturally in the form of correction terms in higher-order power expansions. To demonstrate this, we carry out truncated polynomial expansions of the excess chemical potential up to the sixth power of the composition variables.

Eleno, Luiz T. F.; Schön, Cláudio G.

2014-03-01

8

Photon Interaction Parameters for Some Borate Glasses  

SciTech Connect

Some photon interaction parameters of dosimetric interest such as mass attenuation coefficients, effective atomic number, electron density and KERMA relative to air have been computed in the wide energy range from 1 keV to 100 GeV for some borate glasses viz. barium-lead borate, bismuth-borate, calcium-strontium borate, lead borate and zinc-borate glass. It has been observed that lead borate glass and barium-lead borate glass have maximum values of mass attenuation coefficient, effective atomic number and KERMA relative to air. Hence, these borate glasses are suitable as gamma ray shielding material, packing of radioactive sources etc.

Mann, Nisha [Department of Applied Sciences, Samalkha Group of Institutions, Samalkha-132 101, Haryana (India); Kaur, Updesh; Singh, Tejbir; Sharma, J. K. [Department of Physics, Maharishi Markandeshwar University, Mullana-133 207, Haryana (India); Singh, Parjit S. [Department of Physics, Punjabi University, Patiala-147 002, Punjab (India)

2010-11-06

9

Parameter Dependence of Flow Acoustic Interaction  

NASA Astrophysics Data System (ADS)

The possibility to predict flow acoustic coupling at a sharp edge of an area expansion in a flow duct is explored, starting from the analytical model proposed by Nilsson and Boij. In the model, the vortex shedding is treated as infinitely thin, causing an instability for all frequencies. For small and large values of the Strouhal number, the acoustic field is well defined and can be treated separately from the remaining flow field. For intermediate Strouhal numbers, this classification into acoustic and non-acoustic waves is more complex. In particular, a hydrodynamic wave and higher order, non-propagating acoustic waves are changing properties. The possibility to use the amount of deviation from the asymptotic behaviour as a measure of the strength of the interaction at the edge is explored. It is shown that the interaction is strongly dependent on the area ratio at the duct expansion. Further studies would aim to a more elaborate investigation of the implications of the wave number parameter dependence. The objective would be to better predict the circumstances for strong interaction, in order to design less noisy ventilation and exhaust systems and to enhance dissipation effects.

Boij, Susann

2006-05-01

10

Seasonal variation in ecosystem parameters derived from FLUXNET data  

NASA Astrophysics Data System (ADS)

The carbon dioxide sink is in a complex way related to weather and climate. In order to better understand the relationship and feedbacks, we present a methodology to simulate observed carbon dioxide flux data with a simple vegetation model (5PM) with weekly varying model parameters. The model parameters explain the interaction between vegetation and seasonal climate more general than the flux data. Two parameters (Rref and E0) are related to ecosystem respiration and three parameters (Jm, ? and ?) to photosynthesis and transpiration. We quantified the weekly variability of ecosystem parameters as a function of vegetation type and climate region. After statistical quality checks 121 FLUXNET sites were available for analysis of the weekly varying model parameters. The simulations of these sites have high correlation coefficients (r2=0.6 to 0.8) between the observed and simulated carbon and water fluxes. With weekly parameters we determined average seasonal cycles for the different combinations of vegetation type and climate regions (PFTs). The variation between PFTs is large, which provides an excellent dataset to study the differences in ecosystem characteristics. In general we observed that needleleaf forests and grasslands in warmer climates have relatively constant parameter values during the year. Broadleaf forests in all climate regions have large seasonal variation for each of the five parameters. In boreal regions parameter values are always lower than in temperate regions. A large seasonality of the model parameters indicates a strong relation between vegetation and climate. This suggests that climate change will have the largest impact on the terrestrial carbon fluxes in boreal regions and for deciduous forests, and less for grasslands and evergreen forests.

Groenendijk, M.; van der Molen, M. K.; Dolman, A. J.

2009-03-01

11

Comparison of ionospheric peak parameters derived from different modeling approaches  

NASA Astrophysics Data System (ADS)

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

Mahdi Alizadeh, M.; Schuh, Harald

2014-05-01

12

Seasonal variation in ecosystem parameters derived from FLUXNET data  

NASA Astrophysics Data System (ADS)

The carbon dioxide sink is related in a complex way to weather and climate. In order to better understand the relationship and feedbacks, we present a methodology to simulate observed carbon dioxide flux data with a simple vegetation model (5PM) with weekly varying model parameters. The model parameters explain the interaction between vegetation and seasonal climate more general than the flux data. Two parameters (Rref and E0) are related to ecosystem respiration and three parameters (Jm, λ and ?) to photosynthesis and transpiration. We quantified the weekly variability of ecosystem parameters as a function of vegetation type and climate region. The objective of this paper is to quantify the short term variability of ecosystem parameters of different vegetation types and climate regions. Specific questions we want to address: (1) are the model parameters clearly different between PFTs and (2) do the model parameters vary in an understandable way and (3) does the variation in model parameters have implications for our understanding of the feedback between vegetation and climate? After statistical quality checks, 122 FLUXNET sites were available for analysis of the weekly varying model parameters. The simulations of these sites have high correlation coefficients (r2 = 0.6 to 0.8) between the observed and simulated carbon and water fluxes. With weekly parameters we determined average seasonal cycles for the different combinations of vegetation type and climate regions (PFTs). The variation between PFTs is large, which provides an excellent dataset to study the differences in ecosystem characteristics. In general we observed that needleleaf forests and grasslands in warmer climates have relatively constant parameter values during the year. Broadleaf forests in all climate regions have large seasonal variation for each of the five parameters. In boreal regions parameter values are always lower than in temperate regions. A large seasonality of the model parameters indicates a strong relation between vegetation and climate. This suggests that climate change will have the largest impact on the terrestrial carbon fluxes in boreal regions and for deciduous forests, and less for grasslands and evergreen forests.

Groenendijk, M.; van der Molen, M. K.; Dolman, A. J.

2009-04-01

13

Interaction of gramicidin derivatives with phospholipid monolayers.  

PubMed

A study of the interaction of gramicidin A (gA), tert-butyloxycarbonyl-gramicidin (g-BOC), and desformyl gramicidin (g-des) with dioleoyl phosphatidylcholine (DOPC) and DOPC/phosphatidylserine (PS) mixed monolayers on a mercury electrode is reported in this paper. Experiments were carried out in electrolytes KCl (0.1 mol dm(-3)) and Mg(NO3)2 (0.05 mol dm(-3)). The channel-forming properties of the gramicidins were studied by following the reduction of Tl(I) to Tl(Hg). The frequency dependence of the complex impedance of coated electrode surfaces in the presence and absence of the gramicidins was estimated between 65,000 and 0.1 Hz at potentials of -0.4 V versus Ag/AgCl with 3.5 mol dm(-3) KCl. Epifluorescence microscopy was used to qualitatively correlate the interaction of the gramicidin peptides with dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG) at the air-water interface. gA was shown to form Tl+ conducting channels in a DOPC monolayer, while g-BOC and g-des did not. In DOPC-30% PS (DOPC-0.3PS) layers, there is a marked increase in channel activity of all three gramicidin derivatives. None of the peptides facilitate the permeability of the DOPC-0.3PS layer to Cd2+. All three peptides interact with the layer as shown by capacitance-potential curves and impedance spectroscopy indicated by penetration of the peptide into the dielectric, an increase in surface "roughness", and an increased significance of low-frequency relaxations. The order of interaction is gA > g-des > g-BOC. The epifluorescence study of DPPC and DPPG layers at the air-water interface shows a selective action of the different gramicidins. PMID:15461520

Whitehouse, C; Gidalevitz, D; Cahuzac, M; Koeppe Ii, Roger E; Nelson, A

2004-10-12

14

A study of photon interaction parameters in lung tissue substitutes  

PubMed Central

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

Manjunatha, H. C.

2014-01-01

15

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

16

Great Plains ASPEN Model Development: binary interaction parameters and activity coefficient parameters. Final report  

Microsoft Academic Search

The simulation of the various sections of the Great Plains Coal Gasification Plant involves modelling vapor-liquid equilibria and liquid-liquid equilibria that are highly nonideal. The Peng-Robinson equation of state, modified for water, was used in the simulation of most of the process sections. Interaction parameters established by regression of literature data, using ASPEN's DRS system, along with interaction parameter values

S. S. Stern; M. C. Millman; J. J. Kirman; D. Nwogu

1984-01-01

17

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

18

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

19

Interaction of pyridine derivatives with sepiolite.  

PubMed

In this study, the adsorption behavior of pyridine derivatives, i.e., 2-aminopyridine and 2,2'-bipyridyl, onto sepiolite, a natural clay mineral, has been investigated by bottle adsorption and IR spectroscopic techniques. The results indicate that 2-aminopyridine and 2,2'-bipyridyl molecules adsorb onto sepiolite through hydrogen bonding of the amino groups to the water molecules in the octahedral sheet and to the surface hydroxyls (Si-OH) in the tetrahedral sheet. These findings reveal that pyridine molecules not only adsorb onto the external surface of sepiolite but are also incorporated in its channels and tunnels with adsorption taking place at corners and/or edges, depending on the position of water molecules. A structural model is proposed to account for the orientation of pyridine derivatives in the sepiolite matrix. PMID:16290699

Sabah, E; Celik, M S

2002-07-01

20

Interaction of Pyridine Derivatives with Sepiolite  

Microsoft Academic Search

In this study, the adsorption behavior of pyridine derivatives, i.e., 2-aminopyridine and 2,2?-bipyridyl, onto sepiolite, a natural clay mineral, has been investigated by bottle adsorption and IR spectroscopic techniques. The results indicate that 2-aminopyridine and 2,2?-bipyridyl molecules adsorb onto sepiolite through hydrogen bonding of the amino groups to the water molecules in the octahedral sheet and to the surface hydroxyls

E. Sabah; M. S. Çelik

2002-01-01

21

Effective interaction derived from the BAGEL approach  

NASA Astrophysics Data System (ADS)

Matrix inversion techniques are used to derive an effective hamiltonian for shell-model calculations, which accounts for correlations outside the shell-model space. It is demonstrated that the BAGEL approach leads to a very powerful tool to account for the effects of large Q-spaces in a reliable way. An energy-dependent formulation yields stable results even for cases which are divergent in the perturbative approach due to the presence of intruder states. A first application employing modern one-boson exchange potentials produces results which are in very satisfactory agreement with empirical data.

Skouras, L. D.; Müther, H.

1990-08-01

22

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

ERIC Educational Resources Information Center

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

Chen, Cheng-Te; Wang, Wen-Chung

2007-01-01

23

Design principles for an interactive program derivation system  

NASA Technical Reports Server (NTRS)

The main design principles of an interactive program transformation system called FOCUS are outlined. Its important characteristics are its human-oriented deduction techniques based replacement, emphasis on small search spaces, and the use of a tree structure to organize program derivations. The tree structure presents to the user a static picture of the derivation process and promotes flexibility in the development of derivations. The system keeps track of dependencies between different parts of derivations, and records the derivation activity for later use in automatic replay.

Reddy, Uday S.

1988-01-01

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

Characterizing Tissue with Acoustic Parameters Derived from Ultrasound Data.  

National Technical Information Service (NTIS)

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 ex...

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

2002-01-01

26

Parameter space visualizer: an interactive parameter selection interface for iterative CT reconstruction algorithms  

NASA Astrophysics Data System (ADS)

Previous work indicated that using ordered subsets (OS-SIRT) for iterative CT can optimize the reconstruction performance once optimal settings for parameters such as number of subsets and relaxation factor have been identified. However, recent work also indicated that the optimal settings have dependent relations with regards to the quality of the projection data (such as SNR-level), which are hard to obtain a-priori. In addition, users may also have preferences in trading off between the dependent parameters, such as reconstruction speed and quality, which makes these (independent) parameters even more difficult to determine in an automated manner. Therefore, we devise an effective parameter space navigation interface allowing users to interactively assist parameter selection for iterative CT reconstruction algorithms (here for OS-SIRT). It is based on a 2D scatter plot with six display modes to show different features of the reconstruction results based on the user preferences. It also enables a dynamic visualization by gradual parameter alteration for illustrating the rate of impact of a given parameter constellation. Finally, we note the generality of our approach, which could be applied to assist any parameter selection related systems.

Xu, Wei; Mueller, Klaus

2010-03-01

27

Lidar conversion parameters derived from SAGE II extinction measurements  

NASA Technical Reports Server (NTRS)

SAGE II multiwavelength aerosol extinction measurements are used to estimate mass- and extinction-to-backscatter conversion parameters. The basis of the analysis is the principal component analysis of the SAGE II extinction kernels to estimate both total aerosol mass and aerosol backscatter at a variety of wavelengths. Comparisons of coincident SAGE II extinction profiles with 0.694-micron aerosol backscatter profiles demonstrate the validity of the method.

Thomason, L. W.; Osborn, M. T.

1992-01-01

28

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

29

Restricted parameter space models for testing gene-gene interaction  

PubMed Central

There is a growing recognition that interactions (gene-gene and gene-environment) can play an important role in common disease etiology. The development of cost-effective genotyping technologies has made genome-wide association studies the preferred tool for searching for loci affecting disease risk. These studies are characterized by a large number of investigated SNPs, and efficient statistical methods are even more important than in classical association studies that are done with a small number of markers. In this paper we propose a novel gene-gene interaction test that is more powerful than classical methods. The increase in power is due to the fact that the proposed method incorporates reasonable constraints in the parameter space. The test for both association and interaction is based on a likelihood ratio statistic that has a chi-bar-squared distribution asymptotically. We also discuss the definitions used for “no interaction” and argue that tests for pure interaction are useful in genome-wide studies, especially when using two stage strategies where the analyses in the second stage are done on pairs of loci for which at least one is associated with the trait.

Song, Minsun; Nicolae, Dan L.

2014-01-01

30

Linear elastic properties derivation from microstructures representative of transport parameters.  

PubMed

It is shown that three-dimensional periodic unit cells (3D PUC) representative of transport parameters involved in the description of long wavelength acoustic wave propagation and dissipation through real foam samples may also be used as a standpoint to estimate their macroscopic linear elastic properties. Application of the model yields quantitative agreement between numerical homogenization results, available literature data, and experiments. Key contributions of this work include recognizing the importance of membranes and properties of the base material for the physics of elasticity. The results of this paper demonstrate that a 3D PUC may be used to understand and predict not only the sound absorbing properties of porous materials but also their transmission loss, which is critical for sound insulation problems. PMID:24907783

Hoang, Minh Tan; Bonnet, Guy; Tuan Luu, Hoang; Perrot, Camille

2014-06-01

31

Interaction between subdaily Earth rotation parameters and GPS orbits  

NASA Astrophysics Data System (ADS)

In processing GPS observations the geodetic parameters like station coordinates and ERPs (Earth rotation parameters) are estimated w.r.t. the celestial reference system realized by the satellite orbits. The interactions/correlations between estimated GPS orbis and other parameters may lead to numerical problems with the solution and introduce systematic errors in the computed values: the well known correlations comprise 1) the correlation between the orbital parameters determining the orientation of the orbital plane in inertial space and the nutation and 2) in the case of estimating ERPs with subdaily resolution the correlation between retrograde diurnal polar motion and nutation (and so the respective orbital elements). In this contribution we study the interaction between the GPS orbits and subdaily model for the ERPs. Existing subdaily ERP model recommended by the IERS comprises ~100 terms in polar motion and ~70 terms in Universal Time at diurnal and semidiurnal tidal periods. We use a long time series of daily normal equation systems (NEQ) obtaine from GPS observations from 1994 till 2007 where the ERPs with 1-hour resolution are transformed into tidal terms and the influence of the tidal terms with different frequencies on the estimated orbital parameters is considered. We found that although there is no algebraic correlation in the NEQ between the individual orbital parameters and the tidal terms, the changes in the amplitudes of tidal terms with periods close to 24 hours can be better accmodated by systematic changes in the orbital parameters than for tidal terms with other periods. Since the variation in Earth rotation with the period of siderial day (23.93h, tide K1) in terrestrial frame has in inertial space the same period as the period of revolution of GPS satellites, the K1 tidal term in polar motion is seen by the satellites as a permanent shift. The tidal terms with close periods (from ~24.13h to ~23.80h) are seen as a slow rotation of the celestial pole with periods of about a year and less. We make an estimate of the systematic changes introduced in the orbital parameters in the case if erroneous tidal model is kept fixed in the processing.

Panafidina, Natalia; Seitz, Manuela; Hugentobler, Urs

2013-04-01

32

Derived parameters for NGC 6791 from high-metallicity isochrones  

NASA Technical Reports Server (NTRS)

We have computed 8, 10, and 12 Gyr isochrones and physically consistent models of zero-age red horizontal branch stars for stellar masses between 0.55 and 1.3 solar mass, all at (fe/H) = +0.15. Comparison to the NGC 6791 BVI photometry of Kaluzny & Udalski (1992) and Montgomery et al. (1994) yields an age of 10.0 +/- 0.5 Gyr at an apparent distance modulus 13.49 less than (m-M)(sub V) less than 13.70. The color offsets required to fit the isochrones, combined with the spectroscopic results of Friel & Janes (1993), imply that the foreground reddening to NGC 6791 lies in the range 0.24 greater than E(B -V) greater than 0.19 with +0.27 less than (Fe/H) less than + 0.44. These results are derived using a technique by which we predict color shifts and apply these to the isochrones to simulate progressively higher metallicities. The zero-age horizontal branch model suggest that the red horizontal branch stars of NGC 6791 have masses approximately less than 0.7 solar mass. The masses are similar to those found for M67 red horizontal branch stars by Tripicco et al. (1993) and for globular cluster red horizontal branch stars, even though the M67 progenitors are approximately 0.2 solar-mass more massive, while the progenitors of globular cluster horizontal branch stars are similarly less massive. This suggests the presence of a mechanism, not strongly dependent on metallicity, which reduces stellar envelopes on the zero-age horizontal branch to a given mass rather than by a given amount.

Dorman, Ben; Hufnagel, Beth

1995-01-01

33

Gravity Wave Parameters Derived from High Vertical Resolution U.S. Radiosonde Data  

Microsoft Academic Search

Five years of high vertical resolution U.S. radiosonde data have been analyzed to derive important gravity wave parameters such as intrinsic frequency, vertical wavelength, and vertical and horizontal directions of gravity wave energy propagation. It is found that all these parameters display distinctive latitudinal and seasonal variations. Most dominant gravity wave intrinsic frequencies divided by the Coriolis parameter are around

L. Wang; M. A. Geller; M. J. Alexander; D. Fritts

2003-01-01

34

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

35

Great Plains ASPEN Model Development: binary interaction parameters and activity coefficient parameters. Final report  

SciTech Connect

The simulation of the various sections of the Great Plains Coal Gasification Plant involves modelling vapor-liquid equilibria and liquid-liquid equilibria that are highly nonideal. The Peng-Robinson equation of state, modified for water, was used in the simulation of most of the process sections. Interaction parameters established by regression of literature data, using ASPEN's DRS system, along with interaction parameter values found in the literature, became the database for the simulation. In two of the sections, the Oxygen Plant and the TEG drying of the product SNG, activity coefficient models were used because they gave a better prediction of the phase equilibrium. For the Rectisol unit, which removes hydrogen sulfide from the gas, parameters available from a DOE sponsored contract, Tristate, were used, after verification, for the ASPEN modified version of the RKS. The phases that were predicted using these parameters were checked against literature data and, in most cases, the liquid mole fractions of carbon dioxide predicted by the correlation were within 10% of those reported. A model that would predict phase equilibrium, based on the ionization of Lewis acids and bases and salts, would have been an ideal choice for simulation of the Stretford and Phosam flowsheets. However, only limited temperature dependent liquid activity coefficients data are available in the literature for the ionic species found in the Stretford and Phosam solutions, from which correlation parameters could be obtained by regression. Also, only the flash model can handle this type of calculation; therefore, it was used only to a limited extent in the simulation of the Stretford Unit Absorber. 118 references.

Stern, S.S.; Millman, M.C.; Kirman, J.J.; Nwogu, D.

1984-12-01

36

Some parameters of rockbursts derived from underground seismological measurements  

NASA Astrophysics Data System (ADS)

A total of 240 three-component recordings from 80 rockbursts, which occurred in various coal mines in the Ostrava-Karviná Coal Basin (Czech Republic) between 1993 and 2005, was used to examine the decrease in maximum particle velocities ui (m/s) with a scaled distance of d* = d/?E (m/?J) or d/ 3?E (m/ 3?J) and the rate of predominant frequencies of body waves. The energetic span of rockbursts was within the interval of E = 6.2 × 10 3 - 5.0 × 10 8 J, while calculated hypocentral distances d of four underground seismic stations varied from 0.6 to 7 km. The slopes b of regression straight lines for the maximum particle velocities ui (m/s) of P- and S-waves in the bilogarithmic scale correspond to the values of - 1.004, - 1.297, - 1.183 and - 1.527. The results of the linear regression are as follows: Pmax-waves ui = 1.184 × 10 - 4 × d*- 1.004 (m/s) (square root scaling) Pmax-waves ui = 3.055 × 10 - 3 × d*- 1.297 (m/s) (cube root scaling) Smax-waves ui = 5.280 × 10 - 4 × d *- 1.183 (m/s) (square root scaling) Smax-waves ui = 2.397 × 10 - 2 × d *- 1.527 (m/s) (cube root scaling). The evaluation of the abovementioned dynamic parameters was based on seismic events data gathered in the database of the regional seismic array, and calculations were carried out either by using special programs applied as part of the automated data processing in the computation center, or by usual linear regression approaches. The aim of the detailed analysis of the maximum particle velocity and predominant frequencies was a) to set up input data from underground seismological observations for laboratory experiments dealing with the comparison of rock mass behaviour under modeled laboratory conditions simulating manifestation of rockbursts, and b) to incorporate particle velocity into the design of support in order to control damage and evident devastation of workings by rockbursts. The investigation of peak particle velocities was based on the recognition that they are the best criterion to assess vibration damage to surface structures and in mines.

Holub, Karel; Petroš, Vladimír

2008-08-01

37

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

38

Recursion method for deriving an energy-independent effective interaction  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

39

Partial Derivatives of Surface Wave Phase Velocity with Respect to Physical Parameter Changes within the Earth.  

National Technical Information Service (NTIS)

By using energy equations, which are equivalent to fundamental equations and boundary conditions in surface wave problems, we can get analytical expressions for partial derivatives of phase velocity with respect to changes of physical parameters within th...

H. Takevchi J. Dorman M. Saito

1964-01-01

40

Bulk properties of light deformed nuclei derived from a medium-modified meson-exchange interaction  

Microsoft Academic Search

Deformed Hartree-Fock-Bogoliubov calculations for finite nuclei are carried out. As residual interaction, a Brueckner G-matrix derived from a meson-exchange potential is taken. Phenomenological medium modifications of the meson masses are introduced. The binding energies, radii, and deformation parameters of the carbon, oxygen, neon, and magnesium isotope chains are found to be in good agreement with the experimental data.

F. Grümmer; B. Q. Chen; Z. Y. Ma; S. Krewald

1996-01-01

41

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.

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

2014-01-01

42

Ultlra-intense laser-matter interactions at extreme parameters  

SciTech Connect

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

Hegellich, Bjorn M [Los Alamos National Laboratory

2010-11-24

43

Generalized variational calculus in terms of multi-parameters fractional derivatives  

NASA Astrophysics Data System (ADS)

In this paper, we briefly introduce two generalizations of work presented a few years ago on fractional variational formulations. In the first generalization, we consider the Hilfer's generalized fractional derivative that in some sense interpolates between Riemann-Liouville and Caputo fractional derivatives. In the second generalization, we develop a fractional variational formulation in terms of a three parameter fractional derivative. We develop integration by parts formulas for the generalized fractional derivatives which are key to developing fractional variational calculus. It is shown that many derivatives used recently and their variational formulations can be obtained by setting different parameters to different values. We also define fractional generalized momenta and provide fractional Hamiltonian formulations in terms of the new generalized derivatives. An example is presented to show applications of the formulations presented here. Some possible extensions of this research are also discussed.

Agrawal, Om P.; Muslih, Sami I.; Baleanu, Dumitru

2011-12-01

44

Molecular interactions and thermal instability of coal derived liquids  

SciTech Connect

The purpose of the first part of this research was to investigate interactions between the acid/neutral and base fractions of coal derived asphaltenes. These interactions are thought to cause high viscosities in coal derived liquids which are obtained from catalytic processes. The asphaltenes were obtained from Synthoil and separated into acid/neutral and base fractions. The interactions of model compounds, o-phenylphenol and quinoline, and the acid/neutral and base fractions with these model compounds were studied by proton nuclear magnetic resonance spectroscopy and solution colorimetry. The results indicate that interactions between the acid/neutral and base fractions of the asphaltenes are partially responsible for high viscosities in these synthetic fuels. The purpose of the second part of this research was to investigate the causes and mechanism of formation of deposits from SRC II naphtha in heat exchangers. Formation of these deposits causes plugging and results in pilot plant shutdowns. A deposit obtained from a hydrogenation reactor was examined, and the deposit precursors were concentrated through distillation and ion exchange chromatography. The results indicate that phenols and alkylated nitrogenous bases are responsible for deposit formation. Phenols react through coupling reactions to give arylethers and water. Alkylated nitrogenous bases react by pyrolysis to produce free radicals which crosslink to produce carbonaceous deposits. These reactons have been followed using thermogravimetric analysis, Fourier transform infrared spectroscopy and gas chromatography in the temperature range of 250-400/sup 0/C.

Galya, L.G.

1983-01-01

45

Comparison of two optimization methods to derive energy parameters for protein folding: Perceptron and Z score  

Microsoft Academic Search

Two methods were proposed re- cently to derive energy parameters from known native protein conformations and corresponding sets of decoys. One is based on finding, by means of a perceptron learning scheme, energy parameters such that the native conformations have lower ener- gies than the decoys. The second method maximizes the difference between the native energy and the average energy

Michele Vendruscolo; Leonid A. Mirny; Eugene I. Shakhnovich; Eytan Domany

2000-01-01

46

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

47

Derivation of coupling-of-modes parameters for SAW device analysis by means of boundary element method  

Microsoft Academic Search

A method for derivation of coupling-of-modes (COM) parameters for surface acoustic wave (SAW) device analysis is proposed. Emphasis is laid upon the COM parameter derivation by means of the boundary element method (BEM) analysis, and the COM analysis of a floating electrode unidirectional transducer. Results have shown that the transducer characterization using the COM parameters derived from the BEM analysis

Ken-ya HASHIMOTO; Masatsune YAMAGUCHI

1991-01-01

48

Interaction of bleomycin and its oligonucleotide derivatives with nucleic acids  

NASA Astrophysics Data System (ADS)

Various aspects of interaction of the antitumour glycopeptide antibiotic bleomycin with nucleic acids are considered. Data on equilibrium binding parameters obtained by various physicochemical methods have been collected and compared. The contribution of N- and C-terminal domains of the glycopeptide molecule to the binding with DNA and sequence specificity of DNA cleavage are discussed. Data on a recently created new class of compounds — bleomycin — oligonucleotide conjugates — are presented. These compounds, like antibiotics, possess DNA-cleaving activity (also in a catalytic manner) together with high selectivity towards a selected nucleotide sequence. The bibliography includes 267 references.

Sergeyev, D. S.; Zarytova, V. F.

1996-04-01

49

Molecular interaction of bovine kininogen and its derivatives with papain.  

PubMed

The molecular interaction of bovine kininogen and its derivatives with papain was investigated. High-molecular-weight kininogen (HMWK) or low-molecular-weight kininogen (LMWK) and inactive papain treated with N-[N-(L-3-trans-carboxyoxiran-2-carbonyl)-L-leucyl]agmatine (E-64) formed, respectively, a complex, which was dissociable on sodium dodecyl sulfate polyacrylamide-gel electrophoresis (SDS-PAGE). The densitometric determination of the bands separated on SDS-PAGE and amino acid analysis of the samples extracted from the electrophoresis gel revealed that the complex between kininogen and papain is formed in a molar ratio of one to one. Moreover, analysis of the inhibition of the caseinolytic activity of papain by these kininogens indicated that HMWK, LMWK, and kinin-free derivatives obtained from both kininogens inhibit active papain with a stoichiometry of 1:1. On the other hand, the papain activity was inhibited by two kinds of cyanogen bromide fragments isolated from the heavy chain of HMWK. These two fragments with Ki values of 38 and 0.64 nM corresponded, respectively, to residue Nos. 47 to 243 and Nos. 244-360 of the HMWK heavy chain. These results suggest that in the intact HMWK and LMWK, one of the two potential reactive sites interacts with papain to form a complex and that the other reactive site becomes active only after separation of the two sites. PMID:3182763

Sueyoshi, T; Hara, A; Shimada, T; Kimura, M; Morita, T; Kato, H; Iwanaga, S

1988-08-01

50

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

51

Successive derivatives of Whittaker functions with respect to the first parameter  

NASA Astrophysics Data System (ADS)

Algorithms are given for the computation of the nth derivatives of the Whittaker functions M?, ?( z) and W?, ?( z) with respect to the parameter ?. The algorithms are based on a convergent expansion, due to Buchholz, of M?, ?( z) in series of Bessel functions. Properties of the Buchholz polynomials and algorithms for evaluating the n-derivative of the reciprocal Gamma function are discussed in two appendices.

Abad, J.; Sesma, J.

2003-12-01

52

Comparisons of the Earth Rotation Parameters derived from the IPMS and the BIH.  

NASA Astrophysics Data System (ADS)

The Earth Rotation Parameters (ERP) derived from the IPMS are compared with the BIH for the period from 1967 to 1987 and the IRIS from 1980 to 1987. Differences in the pole positions derived from the IRIS and the IPMS were about 0.002 and 0.007 for x and y, and differences of UT1 - TAI is about -0?02. The pole positions of the IPMS do not show secular variations relative to those of the IRIS.

Ishii, H.; Goto, Y.; Ishikawa, T.

53

Synthesis and interaction of bovine serum albumin with p-hydroxybenzoic acid derivatives.  

PubMed

Three novel p-hydroxybenzoic acid derivatives (HSOP, HSOX, HSCP) were synthesized from p-hydroxybenzoic acid and sulfonamides (sulfamonomethoxine sodium, sulfamethoxazole and sulfachloropyridazine sodium) and characterized by elemental analysis, HNMR and MS. Interactions between derivatives and bovine serum albumin (BSA) were studied by fluorescence quenching spectra, UV-vis absorption spectra and time-resolved fluorescence spectra. Based on fluorescence quenching calculation and Förster's non-radioactive energy transfer theory, the values of the binding constants, basic thermodynamic parameters and binding distances were obtained. Experimental results indicated that the three derivatives had a strong ability to quench fluorescence from BSA and that the binding reactions of the derivatives with BSA were a static quenching process. Thermodynamic parameters showed that binding reactions were spontaneous and exothermic and hydrogen bond and van der Waals force were predominant intermolecular forces between the derivatives and BSA. Synchronous fluorescence spectra suggested that HSOX and HSCP had little effect on the microenvironment and conformation of BSA in the binding reactions but the microenvironments around tyrosine residues were disturbed and polarity around tyrosine residues increased in the presence of HSOP. PMID:22826126

Zhang, Xue-Hong; Liu, Li-Na; Lin, Yi-Jie; Lin, Cui-Wu

2013-01-01

54

Validating a Large Geophysical Data Set: Experiences with Satellite-Derived Cloud Parameters.  

National Technical Information Service (NTIS)

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 H...

J. E. Knighton, R. Kahn, R. D. Haskins

1992-01-01

55

Significance of Landcover Biophysical Parameters Derived from Remote Sensing Data for Environmental Studies  

NASA Astrophysics Data System (ADS)

Remote sensing is a key application in global-change science, being very useful for local and regional climatology and landuse/landcover dynamics analysis. Based on satellite images (LANDSAT TM, ETM and ASTER) of Romanian Black Sea coastal zone, centered on Constantza urban area were derived surface biophysical parameters for 1975 - 2003 period.

Zoran, M.; Stefan, S.

2007-04-01

56

New GHK hydrophobic derivatives: interaction with phospholipid bilayers.  

PubMed

Three hydrophobic derivatives of GHK peptide containing either N-terminal hexanoyl, decanoyl or myristoyl acyl moieties were synthesized. The binding of these peptidolipids to phospholipid bilayers as well as their hemolytic activity were determined. Moreover, the influence of these peptidolipids on several physicochemical properties of liposomes was studied. Binding experiments indicate a high affinity of these peptidolipids for lipids ordered in liposomes. Nevertheless, this interaction does not promote the release of entrapped carboxyfluorescein. Experiments carried out by the asymmetric membrane method (NBD-PE/dithionite) and quenching studies (PC-pyrene/KI) indicate that this association has a protective effect suggesting that the hydrophobic moiety inserts in the external part of the bilayer and the peptide chain remains protruding from the surface hindering the entrance or the approach of reactants to it. The microviscosity of DPPC bilayers determined using TMA-DPH as fluorescent marker was not affected by the presence of peptidolipids. Besides, results indicate that myristoyl-GHK produces total hemolysis at 2.5x10(-4)M but decanoyl and hexanoyl derivatives at 5x10(-4)M induce only 10% of hemolysis. PMID:17383163

Almiñana, N; Alsina, M A; Reig, F

2007-06-15

57

First-principles derivation of reactive transport modeling parameters for particle tracking and PDE approaches  

NASA Astrophysics Data System (ADS)

Both Eulerian and Lagrangian reactive transport simulations in natural media require selection of a parameter that controls the “promiscuity” of the reacting particles. In Eulerian models, measurement of this parameter may be difficult because its value will generally differ between natural (diffusion-limited) systems and batch experiments, even though both are modeled by reaction terms of the same form. And in Lagrangian models, there previously has been no a priori way to compute this parameter. In both cases, then, selection is typically done by calibration, or ad hoc. This paper addresses the parameter selection problem for Fickian transport by deriving, from first principles and D (the diffusion constant) the reaction-rate-controlling parameters for particle tracking (PT) codes and for the diffusion-reaction equation (DRE). Using continuous time random walk analysis, exact reaction probabilities are derived for pairs of potentially reactive particles based on D and their probability of reaction provided that they collocate. Simultaneously, a second PT scheme directly employing collocation probabilities is derived. One-to-one correspondence between each of D, the reaction radius specified for a PT scheme, and the DRE decay constant are then developed. These results serve to ground reactive transport simulations in their underlying thermodynamics, and are confirmed by simulations.

Hansen, Scott K.; Scher, Harvey; Berkowitz, Brian

2014-07-01

58

An empirically-derived taxonomy of interaction primitives for interactive cartography and geovisualization.  

PubMed

Proposals to establish a 'science of interaction' have been forwarded from Information Visualization and Visual Analytics, as well as Cartography, Geovisualization, and GIScience. This paper reports on two studies to contribute to this call for an interaction science, with the goal of developing a functional taxonomy of interaction primitives for map-based visualization. A semi-structured interview study first was conducted with 21 expert interactive map users to understand the way in which map-based visualizations currently are employed. The interviews were transcribed and coded to identify statements representative of either the task the user wished to accomplish (i.e., objective primitives) or the interactive functionality included in the visualization to achieve this task (i.e., operator primitives). A card sorting study then was conducted with 15 expert interactive map designers to organize these example statements into logical structures based on their experience translating client requests into interaction designs. Example statements were supplemented with primitive definitions in the literature and were separated into two sorting exercises: objectives and operators. The objective sort suggested five objectives that increase in cognitive sophistication (identify, compare, rank, associate, & delineate), but exhibited a large amount of variation across participants due to consideration of broader user goals (procure, predict, & prescribe) and interaction operands (space-alone, attributes-in-space, & space-in-time; elementary & general). The operator sort suggested five enabling operators (import, export, save, edit, & annotate) and twelve work operators (reexpress, arrange, sequence, resymbolize, overlay, pan, zoom, reproject, search, filter, retrieve, & calculate). This taxonomy offers an empirically-derived and ecologically-valid structure to inform future research and design on interaction. PMID:24051802

Roth, Robert E

2013-12-01

59

The star cluster population of M 51. II. Age distribution and relations among the derived parameters  

NASA Astrophysics Data System (ADS)

We use archival Hubble Space Telescope observations of broad-band images from the ultraviolet (F255W-filter) through the near infrared (NICMOS F160W-filter) to study the star cluster population of the interacting spiral galaxy M 51. We obtain age, mass, extinction, and effective radius estimates for 1152 star clusters in a region of ~7.3 × 8.1 kpc centered on the nucleus and extending into the outer spiral arms. In this paper we present the data set and exploit it to determine the age distribution and relationships among the fundamental parameters (i.e. age, mass, effective radius). We show the critical dependence of the age distribution on the sample selection, and confirm that using a constant mass cut-off, above which the sample is complete for the entire age range of interest, is essential. In particular, in this sample we are complete only for masses above 5× 104~M? for the last 1 Gyr. Using this dataset we find: i) that the cluster formation rate seems to have had a large increase ~50-70 Myr ago, which is coincident with the suggested second passage of its companion, NGC 5195; ii) a large number of extremely young (<10 Myr) star clusters, which we interpret as a population of unbound clusters of which a large majority will disrupt within the next ~10 Myr; and iii) that the distribution of cluster sizes can be well approximated by a power-law with exponent, -? = -2.2 ± 0.2, which is very similar to that of Galactic globular clusters, indicating that cluster disruption is largely independent of cluster radius. In addition, we have used this dataset to search for correlations among the derived parameters. In particular, we do not find any strong trends between the age and mass, mass and effective radius, nor between the galactocentric distance and effective radius. There is, however, a strong correlation between the age of a cluster and its extinction, with younger clusters being more heavily reddened than older clusters.

Bastian, N.; Gieles, M.; Lamers, H. J. G. L. M.; Scheepmaker, R. A.; de Grijs, R.

2005-03-01

60

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

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.

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

Parameter identification for stochastic hybrid models of biological interaction networks  

Microsoft Academic Search

Based on a model of subtilin production by Bacillus subtilis, in this paper we discuss the parameter identification of stochastic hybrid dynamics that are typically found in biological regulatory networks. In accordance with the structure of the model, identification is split in two subproblems: estimation of the genetic network regulating subtilin production from gene expression data, and estimation of population

Eugenio Cinquemani; Riccardo Porreca; Giancarlo Ferrari-Trecate; John Lygeros

2007-01-01

63

Application of lab derived kinetic biodegradation parameters at the field scale  

NASA Astrophysics Data System (ADS)

Estimating the intrinsic remediation potential of an aquifer typically requires the accurate assessment of the biodegradation kinetics, the level of available electron acceptors and the flow field. Zero- and first-order degradation rates derived at the laboratory scale generally overpredict the rate of biodegradation when applied to the field scale, because limited electron acceptor availability and microbial growth are typically not considered. On the other hand, field estimated zero- and first-order rates are often not suitable to forecast plume development because they may be an oversimplification of the processes at the field scale and ignore several key processes, phenomena and characteristics of the aquifer. This study uses the numerical model BIO3D to link the laboratory and field scale by applying laboratory derived Monod kinetic degradation parameters to simulate a dissolved gasoline field experiment at Canadian Forces Base (CFB) Borden. All additional input parameters were derived from laboratory and field measurements or taken from the literature. The simulated results match the experimental results reasonably well without having to calibrate the model. An extensive sensitivity analysis was performed to estimate the influence of the most uncertain input parameters and to define the key controlling factors at the field scale. It is shown that the most uncertain input parameters have only a minor influence on the simulation results. Furthermore it is shown that the flow field, the amount of electron acceptor (oxygen) available and the Monod kinetic parameters have a significant influence on the simulated results. Under the field conditions modelled and the assumptions made for the simulations, it can be concluded that laboratory derived Monod kinetic parameters can adequately describe field scale degradation processes, if all controlling factors are incorporated in the field scale modelling that are not necessarily observed at the lab scale. In this way, there are no scale relationships to be found that link the laboratory and the field scale, accurately incorporating the additional processes, phenomena and characteristics, such as a) advective and dispersive transport of one or more contaminants, b) advective and dispersive transport and availability of electron acceptors, c) mass transfer limitations and d) spatial heterogeneities, at the larger scale and applying well defined lab scale parameters should accurately describe field scale processes.

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

2003-04-01

64

On the Derivation of Input Parameters for Urban Canopy Models from Urban Morphological Datasets  

NASA Astrophysics Data System (ADS)

Two techniques are analysed to derive mean street width and mean building width from morphological data of real cities: one based on a two-dimensional simplified morphology, and the other based on a three-dimensional regular simplified morphology. For each simplified morphology (two-dimensional and three-dimensional), the sky-view factors (street-to-sky) are computed and compared with the sky-view factors derived from the real morphology for selected districts of three European and two North American cities. The two-dimensional simplified morphology reproduces the real sky-view factors better than the three-dimensional morphology. Since many urban canopy parameterizations represent the city using simplified morphologies, this can be useful information for the derivation of input parameters for urban canopy parameterizations from real morphological data.

Martilli, Alberto

2009-02-01

65

Solar wind and its interaction with the magnetosphere - Measured parameters  

Microsoft Academic Search

The sun and the solar wind are considered in terms of the 'ballerina' model first proposed by Alfven (1977), taking into account high speed streams, the slow solar wind, stream-stream interactions, the relation of streams and magnetic structure, and transients caused by solar activity. The main features of the solar wind behavior are illustrated with the aid of data, covering

R. Schwenn

1981-01-01

66

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

2008-04-22

67

Microscopic calculation of the Majorana parameters of the interacting boson model for the Hg isotopes  

NASA Astrophysics Data System (ADS)

The parameters of the Majorana interaction of the neutron-proton interacting boson model are calculated for the Hg isotopes. The calculations utilize the Otsuka-Arima-Iachello mapping procedure and also lead to predictions for the other boson parameters. The resulting spectra are compared with experimental spectra and those obtained from phenomenological fits.

Druce, C. H.; Pittel, S.; Barrett, B. R.; Duval, P. D.

1985-07-01

68

A simple method to extract spectral parameters using fractional derivative spectrometry.  

PubMed

The nonlinear fitting method, based on the ordinary least squares approach, is one of several methods that have been applied to fit experimental data into well-known profiles and to estimate their spectral parameters. Besides linearization measurement errors, the main drawback of this approach is the high variance of the spectral parameters to be estimated. This is due to the overlapping of individual components, which leads to ambiguous fitting. In this paper, we propose a simple mathematical tool in terms of a fractional derivative (FD) to determine the overlapping band spectral parameters. This is possible because of several positive effects of FD connected with the behavior of its zero-crossing and maximal amplitude. For acquiring a stable and unbiased FD estimate, we utilize the statistical regularization method and the regularized iterative algorithm when a priori constraints on a sought derivative are available. Along with the well-known distributions such as Lorentzian, Gaussian and their linear combinations, the Tsallis distribution is used as a model to correctly assign overlapping bands. To demonstrate the power of the method, we estimate unresolved band spectral parameters of synthetic and experimental infra-red spectra. PMID:15248995

Kharintsev, S S; Salakhov, M Kh

2004-07-01

69

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

70

The Thirring interaction in the two-dimensional axial–current–pseudoscalar derivative coupling model  

Microsoft Academic Search

We reexamine the two-dimensional model of massive fermions interacting with a massless pseudoscalar field via axial-current derivative coupling. The hidden Thirring interaction in the axial-derivative coupling model is exhibited compactly by performing a canonical field transformation on the Bose field algebra and the model is mapped into the Thirring model with an additional vector–current–scalar derivative interaction (Schroer–Thirring model). The Fermi

L. V.. Belvedere; A. F.. Rodrigues

2006-01-01

71

Alkylating derivative of oxotremorine interacts irreversibly with the muscarinic receptor  

SciTech Connect

A 2-chloroethylamine derivative of oxotremorine was studied in pharmacological experiments and muscarinic receptor binding assays. The compound, N-(4-(2-chloroethylmethylamino)-2-butynyl)-2-pyrrolidone (BM 123), forms an aziridinium ion in aqueous solution at neutral pH that stimulates contractions of guinea pig ileum with a potency similar to that of oxotremorine. Following the initial stimulation, there is a long lasting period of lack of sensitivity of the guinea pig ileum to muscarinic agonists. BM 123 also produces muscarinic effects in vivo. When homogenates of the rat cerebral cortex were incubated with BM 123 and assayed subsequently in muscarinic receptor binding assays, a loss of binding capacity for the muscarinic antagonist, (/sup 3/H)N-methylscopolamine ((/sup 3/H)NMS), was noted without a change in affinity. Similar observations were made in (/sup 3/H)1-3-quinuclidinyl benzilate ((/sup 3/H)-QNB) binding assays on the forebrains of mice that had been injected with BM 123 24 hr earlier. The loss in receptor capacity for both (/sup 3/H)NMS and (/sup 3/H)-QNB was prevented by atropine treatment. Kinetic studies of the interaction of BM 123 with homogenates of the rat cerebral cortex in vitro showed that the half-time for the loss of (/sup 3/H)-QNB binding sites increased from 10 to 45 min as the concentration of BM 123 decreased from 10 to 1 ..mu..M. In contrast to the aziridinium ion, the parent 2-chloroethylamine compound and the alcoholic hydrolysis product were largely devoid of pharmacological and binding activity.

Ehlert, F.J.; Jenden, D.J.; Ringdahl, B.

1984-03-05

72

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

73

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

74

Multiscale analysis of satellite-derived vegetation parameters for biogenic VOC emission modeling  

NASA Astrophysics Data System (ADS)

Volatile organic compounds (VOC) emitted by vegetation play an important role in atmospheric chemistry contributing to tropospheric ozone and secondary organic aerosol formation. Quantification of biogenic VOC may be performed using emission modeling tools that require information on vegetation dynamics. For this purpose satellite-derived parameters such as Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI) are considered. However, spatial resolution of the satellite data could be an important source of uncertainties in biogenic VOC quantification. The main objective of the current study is to accomplish a sensitivity analysis of the biogenic emission modeling to the changes in data resolution of the satellite-derived vegetation parameters. This study is performed for an area of 80x 80km2 in Portugal for 2011. Satellite observations provided by DEIMOS-1 (22 m resolution) and MODIS (250m and 1000m resolution) are analyzed for NDVI and LAI. Also, meteorological data from the Weather Research and Forecasting (WRF) model and detailed land cover data are considered by the emission quantification algorithm. Multi-scale analysis of LAI and NDVI was performed. Also, the modeling results are analyzed in terms of spatial and temporal variations of the emissions. The results confirm high sensitivity of the emission model to spatial resolution of the satellite-derived data resulting in about 30% difference in total isoprene emissions for the study area.

Silveira, Carlos; Tchepel, Oxana

2013-08-01

75

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

PubMed Central

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

2012-01-01

76

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

77

Constraining the Symmetry Parameters of the Nuclear Interaction  

NASA Astrophysics Data System (ADS)

One of the major uncertainties in the dense matter equation of state has been the nuclear symmetry energy. The density dependence of the symmetry energy is important in nuclear astrophysics, as it controls the neutronization of matter in core-collapse supernovae, the radii of neutron stars and the thicknesses of their crusts, the rate of cooling of neutron stars, and the properties of nuclei involved in r-process nucleosynthesis. We show that fits of nuclear masses to experimental masses, combined with other experimental information from neutron skins, heavy ion collisions, giant dipole resonances, and dipole polarizabilities, lead to stringent constraints on parameters that describe the symmetry energy near the nuclear saturation density. These constraints are remarkably consistent with inferences from theoretical calculations of pure neutron matter, and, furthermore, with astrophysical observations of neutron stars. The concordance of experimental, theoretical, and observational analyses suggests that the symmetry parameters Sv and L are in the range 29.0-32.7 MeV and 40.5-61.9 MeV, respectively, and that the neutron star radius, for a 1.4 M ? star, is in the narrow window 10.7 km

Lattimer, James M.; Lim, Yeunhwan

2013-07-01

78

CONSTRAINING THE SYMMETRY PARAMETERS OF THE NUCLEAR INTERACTION  

SciTech Connect

One of the major uncertainties in the dense matter equation of state has been the nuclear symmetry energy. The density dependence of the symmetry energy is important in nuclear astrophysics, as it controls the neutronization of matter in core-collapse supernovae, the radii of neutron stars and the thicknesses of their crusts, the rate of cooling of neutron stars, and the properties of nuclei involved in r-process nucleosynthesis. We show that fits of nuclear masses to experimental masses, combined with other experimental information from neutron skins, heavy ion collisions, giant dipole resonances, and dipole polarizabilities, lead to stringent constraints on parameters that describe the symmetry energy near the nuclear saturation density. These constraints are remarkably consistent with inferences from theoretical calculations of pure neutron matter, and, furthermore, with astrophysical observations of neutron stars. The concordance of experimental, theoretical, and observational analyses suggests that the symmetry parameters S{sub v} and L are in the range 29.0-32.7 MeV and 40.5-61.9 MeV, respectively, and that the neutron star radius, for a 1.4 M{sub Sun} star, is in the narrow window 10.7 km

Lattimer, James M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Lim, Yeunhwan, E-mail: james.lattimer@stonybrook.edu, E-mail: yeunhwan.lim@gmail.com [Department of Physics Education, Daegu University, Gyeongsan 712-714 (Korea, Republic of)

2013-07-01

79

Solar wind and its interaction with the magnetosphere - Measured parameters  

NASA Astrophysics Data System (ADS)

The sun and the solar wind are considered in terms of the 'ballerina' model first proposed by Alfven (1977), taking into account high speed streams, the slow solar wind, stream-stream interactions, the relation of streams and magnetic structure, and transients caused by solar activity. The main features of the solar wind behavior are illustrated with the aid of data, covering one complete solar rotation in 1974/1975, which were obtained with instruments aboard the Helios-1 solar probe. It is pointed out that the solar wind acts like a huge buffer pushing onto the earth's magnetosphere with a highly variable pressure. Of the energy in the highly variable solar wind reservoir only a tiny fraction is absorbed by the magnetosphere in an obviously very nonstationary way.

Schwenn, R.

80

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

81

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

SciTech Connect

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

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

1987-01-01

82

Vanishing order-parameter critical fluctuations of an absorbing-state transition driven by long-range interactions  

NASA Astrophysics Data System (ADS)

We study the critical behavior of the absorbing-state phase transition depicted by a contact process one-dimensional model system with power-law decaying interactions. The system dynamical processes include particle creation at a rate which decays with the distance from the nearest particle as 1/r?. This model displays an absorbing-state phase transition with critical exponents varying continuously with the interaction exponent ?. Here, we provide a finite-size scaling analysis of the stationary order-parameter density, one of its moment ratio, its logarithmic derivative, and fluctuations. We also follow the short-time relaxation dynamic of these quantities to estimate their corresponding dynamical critical exponents. The estimated exponents are shown to be consistent with the hyperscaling relation. Further, we report an unconventional regime on which the critical order-parameter fluctuations vanish in the thermodynamic limit.

Argolo, C.; Quintino, Yan; Barros, Pedro H.; Lyra, M. L.

2013-03-01

83

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 ...

84

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

PubMed Central

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

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

2012-01-01

85

Derivation of parameters used in Spectrum for eligibility for antiretroviral therapy and survival on antiretroviral therapy  

PubMed Central

Background The Spectrum projection package uses estimates of national HIV incidence, demographic data and other assumptions to describe the consequences of the HIV epidemic in low and middle-income countries. The default parameters used in Spectrum are updated every 2?years as new evidence becomes available to inform the model. This paper reviews the default parameters that define the course of HIV progression among adults and children in Spectrum. Methods For adults, data available from published and grey literature and data from the ART-LINC International epidemiologic Database to Evaluate AIDS (IeDEA) collaboration were combined to estimate survival among those who started antiretroviral therapy (ART). For children, a review of published material on survival on ART and survival on ART and cotrimoxazole was used to derive survival probabilities. Historical data on the distribution of CD4 cell counts and CD4 cell percentages by age among children who were not treated (before treatment was available) were used to progress children from seroconversion to different CD4 cell levels. Results Based on the updated evidence estimated survival among adults aged over 15?years in the first year on ART was 86%, while in subsequent years survival was estimated at 90%. Survival among children during the first year on ART was estimated to be 85% and for subsequent years 93%. Discussion The revised default parameters based on additional data will make Spectrum estimates more accurate than previous rounds of estimates.

Lewden, Charlotte; Brinkhof, Martin W G; Dabis, Francois; Tassie, Jean-Michel; Souteyrand, Yves; Stover, John

2010-01-01

86

Genetic parameters derived from using a biological model of lactation on records of commercial dairy cows.  

PubMed

The object of this study was to investigate the genetics of lactation curve parameters derived from a biological model of lactation and the relationships among them. This biological model fitted 2 logistic curves to mimic the initial increase in milk secretory cell numbers in early lactation and the progression of apoptosis in late lactation. Records from 82,255 Holstein-Friesian heifers from commercial dairy herds in the United Kingdom, recorded from 1994 to 2003, were analyzed. The heritabilities of 2 lactation curve parameters, maximum secretion potential and relative cell death rate, were 0.27 and 0.08 respectively. Maximum secretion potential was highly genetically correlated with peak yield (0.99), and relative cell death rate was highly correlated with persistency of lactation (0.84). Heritability values for the traits analyzed showed a characteristic pattern. Total milk yield traits, maximum secretion potential, and peak yield had similar and moderate heritabilities (approximately 0.3). Traits associated with late lactation had lower heritability values (approximately 0.1), whereas day of peak yield and early lactation traits had little genetic variation. The permanent environmental variance of the various traits ranged from 0.08 to 0.26 of the phenotypic variance. Parameters from the 2 logistic curves were not highly correlated, suggesting that selection programs could be devised to exploit genetic variation in both aspects of lactation independently. PMID:18765622

Albarrán-Portillo, B; Pollott, G E

2008-09-01

87

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

PubMed

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

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

2014-02-24

88

Activation parameters for the recombination reaction of intramolecular radical pairs generated from the radical diffusion-inhibited HABI derivative.  

PubMed

Activation parameters were determined for the recombination of radical pairs arising from newly designed, photochromic, radical diffusion-restricted hexaarylbiimidazole (HABI) derivative. We have developed a new type of radical diffusion-inhibited HABI derivative, which contains two equivalent HABI units and yields a tetraradical with four equivalent 2,4,5-triphenylimidazolyl radical (TPIR) units by photoirradiation. This radical dimerization proceeds by a successive first-order reaction from the tetraradical to the parent molecule via a diradical. The rate constants of each reaction were determined from the decay profile of EPR signal intensities. The entropies of activation (DeltaS(double dagger)) for the first and the successive dimerization steps were estimated to be -178.5 and -205.5 J K(-1) mol(-1), respectively. Within the experimental temperature range, the radical dimerizations are entropy-controlled (-TDeltaS(double dagger) > DeltaH(double dagger)). The large negative DeltaS(double dagger) values imply a highly ordered transition state, indicating that the radical dimerizations occur when the TPIR units interact at a specific orientation. The present study demonstrates the availability of radical diffusion-inhibited HABI for the kinetic study of radical-radical reaction. PMID:18563869

Hatano, Sayaka; Abe, Jiro

2008-07-10

89

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

SciTech Connect

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

Jannik, T.

2013-03-14

90

Luttinger parameters of interacting fermions in one dimension at high energies  

NASA Astrophysics Data System (ADS)

Interactions between electrons in one dimension are fully described at low energies by only a few parameters of the Tomonaga-Luttinger model, which is based on linearization of the spectrum. We consider a model of spinless fermions with short-range interaction via the Bethe-Ansatz technique and show that a Luttinger parameter emerges in an observable beyond the low-energy limit. A distinct feature of the spectral function, the edge that marks the lowest possible excitation energy for a given momentum, is parabolic for arbitrary momenta and the prefactor is a function of the Luttinger parameter, K.

Tsyplyatyev, O.; Schofield, A. J.

2013-09-01

91

Precise derivation for the equivalent circuit parameters of a crystal resonator with series capacitor.  

PubMed

An exact formula for the equivalent circuit of a crystal resonator in series with a capacitor is derived. Network analysis is used to obtain an exact formula for the equivalent circuit parameters without applying any approximations. The result is an expansion of that obtained by those who used assumptions regarding high frequency, high quality factor, high capacitance ratio, and so on. Hence, this formula can be used for instances of low quality factor or low capacitance ratio, and even for the actual inductor-capacitor network as long as these devices have the same equivalent circuits. The enhanced accuracy of the new formula extends itself to oscillator frequency calibration, temperature compensation, and electronic frequency control. PMID:22718883

Huang, Xianhe; Liu, Dong; Wang, Yan; Chen, Yan

2012-06-01

92

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

93

Stabilization of Satellite derived Gravity Field Coefficients by Earth Rotation Parameters  

NASA Astrophysics Data System (ADS)

Recent gravity field missions (e.g. GRACE) provide monthly solutions for the time-variable Earth gravity field. However, the low-degree harmonic coefficients are poorly resolved, especially those of degree 2. The Earth rotation parameters (ERP), consisting of polar motion and lod, and the gravity field coefficients (GFC) of degree 2 are linked by the Euler-Liouville Equation. Thus the consideration of ERP time series helps to improve the estimates of GFC2. Due to the covariances between the GFC of degree 2 and further low-degree gravity field coefficients (up to degree 10) the residuals of the first group of coefficients has to be propagated to the second group in order to guarantee an overall consistency. Previous work has shown a significant influence of ERP on GFC up to degree 4 with the results depending on the covariances assumed a priori. This presentation shows the result of a consistent joint analysis of GRACE derived GFC and ERP in an extended Gauss-Helmert model which includes a sophisticated variance-covariance component estimation (VCCE). As the covariances of the GRACE derived GFC are largely not known, some different variance-covariance structures are assumed and estimated with the VCCE. The results are compared and discussed.

Heiker, A.; Kutterer, H.; Müller, J.

2009-04-01

94

Minimizing the statistical error of resonance parameters and cross-sections derived from transmission measurements  

NASA Astrophysics Data System (ADS)

Total neutron cross-sections are usually measured by a transmission experiment. In this experiment the transmission through a sample is measured by taking the ratio of the background corrected counts measured with and without the sample in the beam. This procedure can be optimized to reduce the statistical error in the measured cross-section. The objective is to find the optimal sample thickness and time split between the open beam, sample and background measurements. An optimization procedure for constant cross-section measurement is derived and extended to the area under the total cross-section curve of an isolated resonance. The minimization of the statistical error in the measured area also minimizes the statistical error in the inferred neutron width. Comparison of the analytical expression developed in this paper and resonance parameters obtained from the SAMMY (Updated users's guide for SAMMY: Multilevel R-Matrix fits to neutron data using Bays' equation, version m2, ORNTL/TM/-9179/R4) code is shown. The comparison was done with both simulated data and data from transmission experiments that were previously done at RPI. It is shown that the analytical expression can be used as a design tool for optimizing transmission experiments. This will consequently result in more accurate measurements of resonance parameters and can shorten the time required to reach a given accuracy.

Danon, Yaron; Block, R. C.

2002-06-01

95

General hybrid projective complete dislocated synchronization with non-derivative and derivative coupling based on parameter identification in several chaotic and hyperchaotic systems  

NASA Astrophysics Data System (ADS)

According to the Lyapunov stability theorem, a new general hybrid projective complete dislocated synchronization scheme with non-derivative and derivative coupling based on parameter identification is proposed under the framework of drive-response systems. Every state variable of the response system equals the summation of the hybrid drive systems in the previous hybrid synchronization. However, every state variable of the drive system equals the summation of the hybrid response systems while evolving with time in our method. Complete synchronization, hybrid dislocated synchronization, projective synchronization, non-derivative and derivative coupling, and parameter identification are included as its special item. The Lorenz chaotic system, Rössler chaotic system, memristor chaotic oscillator system, and hyperchaotic Lü system are discussed to show the effectiveness of the proposed methods.

Sun, Jun-Wei; Shen, Yi; Zhang, Guo-Dong; Wang, Yan-Feng; Cui, Guang-Zhao

2013-04-01

96

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

97

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

PubMed

2,2,6,6-Tetramethylpiperidine-1-yloxyl derivatives substituted with either hydrogen bonding [-OH, -OSO(3)H] or ionic [-OSO(3) (-)Na(+), -OSO(3) (-)K(+), N(+)(CH(3))(3)I(-), N(+)(CH(3))(3) N(-)(SO(2)-CF(3))(2)] substituents are investigated in 1-butyl-3-methylimidazolium tetrafluoroborate over a wide temperature range covering both glassy and viscous states. The Vogel-Fulcher-Tammann equation describes the temperature dependence of the ionic liquid viscosity. Quantum chemical calculations of the spin probes at the UB3LYP/6-311(2d,p++) level are done to describe the dependence of the spin density on nitrogen on the substitution pattern of the 4-position of the probe. The results of these calculations are also used to understand the experimental results obtained by applying the Spernol-Gierer-Wirtz theory to analyze the viscosity dependence of the rotational correlation time of the spin probes. Significant differences are found between 2,2,6,6-tetramethylpiperidine-1-yloxyl and its derivatives containing substituents that are able to form hydrogen bonds with the ionic liquid. Moreover, derivatives substituted with ionic groups at the 4-position have a large effect on temperature-induced solvent viscosity, as this is particularly dependent on the nature of the substituent at the 4-position. These dependencies include the temperature region that can be used to describe interactions between the spin probes and the ionic liquid, diffusion into the free volume during non-activated (neutral spin probes) and activated (charged spin probes) processes. Additional parameters are the radii of the ionic liquid and the spin probes, which are calculated and measured approximately. In addition, the temperature dependence of the isotropic hyperfine coupling constants of the spin probes results in information about the micropolarity of the ionic liquid. At room temperature, this is comparable to that of the solvent dimethylsulfoxide. PMID:18470856

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

2008-06-23

98

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

99

Thermal and Magnetic Parameters in Solar Flares Derived from GOES X-Ray Light Curves  

NASA Astrophysics Data System (ADS)

The purpose of this study is to reproduce the GOES X-ray (1-8 Å) light curves of the impulsive phase of 20 solar flares and to estimate the thermal and magnetic parameters in flare loops. The expected X-ray light curves are calculated from the values of the coronal field strength and inflow velocity under some assumptions. We used the magnetic reconnection heating model of Shibata and Yokoyama (2002, ApJ, 577, 422), photospheric vector magnetic field data, and a simple 1-D flare loop model. It is found the maximum inflow velocities are ˜ 107cm s-1, and that the maximum magnetic reconnection rates are 0.006-0.9, and further that the characteristic coronal field strengths are 6-100 G. Using the thermal and magnetic parameters derived, we found that geometrically our calculated flare loops are higher than the potential fields that model the postflare loops, and are also higher than the preflare loops containing magnetic free energy that is large enough to provide the thermal energy of a flare. Hence, we conclude that the plasma ? value would be near unity in the flare loops we studied, and the magnetic field lines shrunk during the decay phase. The downward velocities of the field-line shrinkage are estimated to be 106-107cm s-1 except one event. The height of the reconnection point was roughly estimated to be from 1010cm to 4 × 1010cm. We propose a new interpretation of the Neupert effect, and also discuss a temporal relationship between the X-ray flux and the flare loop heating.

Yamamoto, Tetsuya T.; Sakurai, Takashi

2010-06-01

100

Microscopic derivation of the interacting boson Hamiltonian from a phenomenological interaction  

NASA Astrophysics Data System (ADS)

A microscopic interacting boson model calculation is performed for Ba isotopes. The boson interactions are constructed by applying the Otsuka-Arima-Iachello mapping procedure to the phenomenological interactions given in previous systematic studies for A ~ 130 nuclei. The theoretical energy levels in the IBM are found to be in good agreement with those of the pair-truncated shell model.

Yoshinaga, N.; Higashiyama, K.

2005-01-01

101

A derivation of linear elastic energies from pair-interaction atomistic systems  

Microsoft Academic Search

Pair-interaction atomistic energies may give rise, in the framework of the passage from discrete systems to continuous variational problems, to nonlinear energies with genuinely quasiconvex integrands. This phenomenon takes place even for simple harmonic interactions as shown by an example by Friesecke and Theil (19). On the other hand, a rigorous derivation of linearly elastic energies from energies with quasiconvex

Andrea Braides; Margherita Solci; Enrico Vitali

2007-01-01

102

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

NASA Astrophysics Data System (ADS)

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

Mao, Albert H.; Pappu, Rohit V.

2012-08-01

103

[Drug interactions between coumarin derivatives and antimycotics: also with topical antifungal agents].  

PubMed

The imidazole derivative miconazole is often used to treat fungal infections of the skin, mouth and gastrointestinal tract. Used concomitantly with coumarin derivatives, it may enhance their anticoagulant effects by inhibiting the CYP2C9 isoenzyme; an interaction which has been well described for oral and vaginal administrations of miconazole. In daily practice, however, cutaneous formulations can also cause clinically relevant drug interactions after having been absorbed through the skin. We describe 4 patients in whom topically applied miconazole enhanced the effect of coumarin derivatives. These cases concern reports received by the Netherlands Pharmacovigilance Centre Lareb between April 2001 and April 2012. PMID:23343733

Jessurun, Naomi T; van Puijenbroek, Eugène P

2013-01-01

104

Solid\\/liquid- and vapor-phase interactions between cellulose- and lignin-derived pyrolysis products  

Microsoft Academic Search

Solid\\/liquid- and vapor-phase interactions between cellulose- and lignin (Japanese cedar milled wood lignin)-derived pyrolysis products were studied under the conditions of N2\\/600°C\\/40–80s. A dual-space closed ampoule reactor was used to eliminate the solid\\/liquid-phase interactions, and careful comparison of the resulting data with those of the pyrolysis of the mixed samples gave some insights into the solid\\/liquid- and vapor-phase interactions separately.

Takashi Hosoya; Haruo Kawamoto; Shiro Saka

2009-01-01

105

Data Base Analyzer and Parameter Estimator (DBAPE) Interactive Computer Program. User's Manual.  

National Technical Information Service (NTIS)

The Data Base Analyzer and Parameter Estimator (DBAPE) is an interactive computer program that provides a link between two of EPA's development products -- an environmental model and a data base. DBAPE was created to encourage and support the use of the R...

J. C. Imhoff J. L. Kittle P. R. Hummel R. F. Carsel

1990-01-01

106

Variance of estimated DTI-derived parameters via first-order perturbation methods  

Microsoft Academic Search

In typical applications of diffusion tensor imaging (DTI), DT- derived quantities are used to make a diagnostic, therapeutic, or scientific determination. In such cases it is essential to char- acterize the variability of these tensor-derived quantities. Para- metric and empirical methods have been proposed to estimate the variance of the estimated DT, and quantities derived from it. However, the former

Lin-Ching Chang; Cheng Guan Koay; Carlo Pierpaoli; Peter J. Basser

2007-01-01

107

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

108

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

109

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

110

Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Power Spectra and WMAP-derived Parameters  

NASA Astrophysics Data System (ADS)

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 ?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 ?CDM model, this improvement allows us to place tighter constraints on the matter density from WMAP data alone, ? m h 2 = 0.1334+0.0056 -0.0055, and on the epoch of matter-radiation equality, z eq = 3196+134 -133. The temperature-polarization (TE) spectrum is detected in the seven-year data with a significance of 20?, compared to 13? with the five-year data. We now detect the second dip in the TE spectrum near l ~ 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? significance when averaged over l = 2-7: l(l + 1)C EE l /(2?) = 0.074+0.034 -0.025 ?K2 (68% CL). We now detect the high-l, 24 <= l <= 800, EE spectrum at over 8?. 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 BB l /(2?) < 0.055 ?K2 (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 ?CDM model: the best-fit TT spectrum has an effective ?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 ?CDM parameters has been reduced by a factor of 1.5 relative to the five-year volume, while the ?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, ns , is biased high, but only by 0.09?, while the remaining parameters are biased by <0.15?. 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 eff>2.7(95%CL). Also, using WMAP data alone, the primordial helium mass fraction is found to be Y He = 0.28+0.14 -0.15, and with data from higher-resolution cosmic microwave background experiments included, we now establish the existence of pre-stellar helium at >3?. These new WMAP measurements provide important tests of big bang cosmology. WMAP is the result of a partnership between Princeton University and NASA's Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.

Larson, D.; Dunkley, J.; Hinshaw, G.; Komatsu, E.; Nolta, M. R.; Bennett, C. L.; Gold, B.; Halpern, M.; Hill, R. S.; Jarosik, N.; Kogut, A.; Limon, M.; Meyer, S. S.; Odegard, N.; Page, L.; Smith, K. M.; Spergel, D. N.; Tucker, G. S.; Weiland, J. L.; Wollack, E.; Wright, E. L.

2011-02-01

111

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

112

Estimating kinetic and thermodynamic parameters from single molecule enzyme-inhibitor interactions.  

PubMed

We report the application of recently developed microscopic models to estimate the apparent kinetic and thermodynamic parameters in a single molecule force spectroscopy study of the carbonic anhydrase enzyme and a complementary sulfonamide inhibitor. The most probable rupture force for the enzyme-inhibitor interaction shows a nonlinear dependency on the log-loading rate. Estimates for the kinetic and thermodynamic parameters were obtained by fitting the nonlinear dependency to linear cubic potential and cusp potential models and compared to the standard Bell-Evans model. The reliability of the estimated parameters was verified by modeling the experimental rupture force distributions by the theoretically predicted distributions at rupture. We also report that linkers that are attached to the enzyme and inhibitor show appreciable effects on the apparent kinetic and thermodynamic parameters. PMID:18808161

Porter-Peden, Laura; Kamper, Sarah G; Wal, Mark Vander; Blankespoor, Ronald; Sinniah, Kumar

2008-10-21

113

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.

Malhotra, Sony; Sankar, Kannan; Sowdhamini, Ramanathan

2014-01-01

114

Pulse-to-pulse interaction analysis and parameter optimization for future-generation ophthalmic laser systems  

NASA Astrophysics Data System (ADS)

The immediate pulse-to-pulse interaction becomes more and more important for future-generation high-repetition rate ophthalmic laser systems. Therefore, we investigated the interaction of two laser pulses with different spatial and temporal separation by time-resolved photography. There are various different characteristic interaction mechanisms which are divided into 11 interaction scenarios. Furthermore, the parameter range has been constricted regarding the medical application; here, the efficiency was optimized to a maximum jet velocity along the scanning axis with minimum applied pulse energy as well as unwanted side effects at the same time. In conclusion, these results are of great interest for the prospective optimization of the ophthalmic surgical process with future-generation fs-lasers.

Tinne, N.; Kaune, B.; Bleeker, S.; Lubatschowski, H.; Krüger, A.; Ripken, T.

2014-02-01

115

An optimized wild bootstrap method for evaluation of measurement uncertainties of DTI-derived parameters in human brain  

Microsoft Academic Search

Evaluation of measurement uncertainties (or errors) in diffusion tensor-derived parameters is essential to quantify the sensitivity and specificity of these quantities as potential surrogate biomarkers for pathophysiological processes with diffusion tensor imaging (DTI). Computational methods such as the Monte Carlo simulation have provided insights into characterization of the measurement uncertainty in DTI. However, due to the complexity of real brain

Tong Zhu; Xiaoxu Liu; Patrick R. Connelly; Jianhui Zhong

2008-01-01

116

The impact of an extra background of relativistic particles on the cosmological parameters derived from the cosmic microwave background  

NASA Astrophysics Data System (ADS)

< Recent estimates of cosmological parameters derived from cosmic microwave background (CMB) anisotropies are based on the assumption that we know the precise amount of energy density in relativistic particles in the Universe, ?rel, at all times. There are, however, many possible mechanisms that can undermine this assumption. In this paper we investigate the effect that removing this assumption has on the determination of the various cosmological parameters. We obtain fairly general bounds on the redshift of equality, . We show that ?rel is nearly degenerate with the amount of energy in matter, ?m, and that its inclusion in CMB parameter estimation also affects the present constraints on other parameters such as the curvature or the scalar spectral index of primordial fluctuations. This degeneracy has the effect of limiting the precision of parameter estimation from the MAP satellite, but it can be broken by measurements on smaller scales such as those provided by the Planck satellite mission.

Bowen, R.; Hansen, S. H.; Melchiorri, A.; Silk, Joseph; Trotta, R.

2002-08-01

117

Aspects of secondary bonding intramolecular interaction in organomercury and organochalcogen derivatives  

Microsoft Academic Search

Recent trends in the area of intramolecularly coordinated organomercury and organochalcogens derivatives are reviewed. Intramolecular\\u000a coordination in organomercury derivatives facilitates the formation of mercurametallamacrocycle and leads to novel metal–metal\\u000a interaction with closed shell ions. It also plays a key role in stabilizing telluroxanes as well as in the activation of chalcogen–carbon\\u000a bonds.\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a Graphical Abstract Secondary bonding interactions play vital role in

SAGAR SHARMA; TAPASH CHAKRABORTY; KRITI SRIVASTAVA; HARKESH B SINGH

118

The Use of Invariant Item Parameters to Derive an Absolute Score Metric.  

ERIC Educational Resources Information Center

A method for determining invariant item parameters is presented, along with a scheme for obtaining test scores which are interpretable in terms of a common metric. The method assumes a unidimensional latent trait and uses a three parameter normal ogive model. The assumptions of the model are explored, and the methods for calculating the proposed…

Bradshaw, Charles W., Jr.

119

A distribution parameter derived for rectangular channels and simulated subchannel geometry  

Microsoft Academic Search

The distribution parameter of the drift-flux model has been developed for a rectangular channel and a simulated boiling water reactor (BWR) subchannel. The void fraction prediction by the subchannel drift-flux code CANAL is demonstrated for heated rectangular channels. Intrasubchannel flow and void profiles are considered for subchannel model development. Distribution parameter Câ is found to be very sensitive to variation

Khan

1990-01-01

120

Starting-structure dependence of nanosecond timescale inter-substate transitions and reproducibility of MD-derived order parameters  

PubMed Central

Factors affecting the accuracy of molecular dynamics (MD) simulations are investigated by comparing generalized order parameters for backbone NH vectors of the B3 immunoglobulin-binding domain of streptococcal protein G (GB3) derived from simulations with values obtained from NMR spin relaxation (Yao L, Grishaev A, Cornilescu G, Bax A. J Am Chem Soc 2010; 132: 4295–309.). Choices for many parameters of the simulations, such as buffer volume, water model, or salt concentration, have only minor influences on the resulting order parameters. In contrast, seemingly minor conformational differences in starting structures, such as orientations of sidechain hydroxyl groups, resulting from applying different protonation algorithms to the same structure, have major effects on backbone dynamics. Some, but not all, of these effects are mitigated by increased sampling in simulations. Most discrepancies between simulated and experimental results occur for residues located at the ends of secondary structures and involve large amplitude nanosecond timescale transitions between distinct conformational substates. These transitions result in autocorrelation functions for bond vector reorientation that do not converge when calculated over individual simulation blocks, typically of length similar to the overall rotational diffusion time. A test for convergence before averaging the order parameters from different blocks results in better agreement between order parameters calculated from different sets of simulations and with NMR-derived order parameters. Thus, MD-derived order parameters are more strongly affected by transitions between conformational substates than by fluctuations within individual substates themselves, while conformational differences in the starting structures affect the frequency and scale of such transitions.

Zeiske, Tim; Stafford, Kate A.; Friesner, Richard A.; Palmer, Arthur G.

2012-01-01

121

Investigation of interaction parameters in mixed micelle using pulsed field gradient NMR spectroscopy.  

PubMed

Pulsed field gradient NMR spectroscopy was used to determine the partitioning of surfactant between monomeric and micellar forms in a mixed CTAB (hexadecyltetramethylammonium bromide) and Triton X-100 [p-(1,1,3-tetramethylbutyl)polyoxyethylene] system. In addition, potentiometric and surface tension measurements were used to determine the free concentration of ionic surfactant and the critical micelle concentration (CMC) of mixtures of n-alkyltrimethylammonium bromide (C(n)TAB, n=12, 14, 16, 18) and Triton X-100. Regular solution theory cannot describe the behavior of the activity coefficient and the excess Gibbs free energy of mixtures of ionic and nonionic surfactants. To overcome these shortcomings, we developed a new model that combines Van Laar expressions and the theory of nonrandom mixing in mixed micelles. The Van Laar expressions contain an additional parameter, rho, which reflects differences in the size of the components of the mixture. Nonrandom mixing theory was introduced to describe nonrandom mixing in mixed micelles. This effect was modeled by a packing parameter, P*. The proposed model provided a good description of the behavior of binary surfactant mixtures. The results indicated that head group size and packing constraints are important contributors to nonideal surfactant behavior. In addition, the results showed that as the chain length of the C(n)TAB molecule in C(n)TAB/Triton X-100 mixtures was increased, the head group size parameter remained constant, but the interaction and packing parameters increased. Increase of the temperature caused an increase in the interaction parameter beta and a decrease in the packing parameter (P*). PMID:15797433

Gharibi, H; Javadian, S; Sohrabi, B; Behjatmanesh, R

2005-05-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

123

Automation of SimSphere Land Surface Model Use as a Standalone Application and Integration With EO Data for Deriving Key Land Surface Parameters  

NASA Astrophysics Data System (ADS)

Use of simulation process models has played a key role in extending our abilities to study Earth system processes and enhancing our understanding on how different components of it interplay. Use of such models combined with Earth Observation (EO) data provides a promising direction towards deriving accurately spatiotemporal estimates of key parameters characterising land surface interactions, by combining the horizontal coverage and spectral resolution of remote sensing data with the vertical coverage and fine temporal continuity of those models. SimSphere is such a software toolkit written in Java for simulating the interactions of soil, vegetation and atmosphere layers of the Earth's land surface. Its use is at present continually expanding worldwide both as an educational and as a research tool for scientific investigations. It is being used either as a stand-alone application or synergistically with EO data. Herein we present recent advancements introduced to SimSphere in different aspects of the model aiming to make its use more robust when used both as a standalone application and synergistically with EO data. We have extensively tested and updated the model code, as well as enhanced it with new functionalities. These included for example taking into account the thermal inertia variation in soil moisture, simulating additional parameters characterising land surface interactions, automating the model use when integrating it with EO data via the "triangle" method and developing batch processing operations. Use of these recently introduced to the model functionalities are illustrated herein using a variety of examples. Our work is significant to the users' community of the model and very timely, given the potential use of SimSphere in an EO-based method being under development for deriving operationally regional estimates of energy fluxes and soil moisture from EO data provided by non-commercial vendors. KEYWORDS: land surface interactions, land surface process model, SimSphere, triangle

Petropoulos, George P.; Konstas, Ioannis; Carlson, Toby N.

2013-04-01

124

Can Self-Inhibitory Peptides be Derived from the Interfaces of Globular Protein-Protein Interactions?  

PubMed Central

In this study, we assess on a large scale the possibility of deriving self-inhibitory peptides from protein domains with globular architectures. Such inhibitory peptides would inhibit interactions of their origin domain by mimicking its mode of binding to cognate partners, and could serve as promising leads for rational design of inhibitory drugs. For our large-scale analysis, we analyzed short linear segments that were cut out of protein interfaces in-silico in complex structures of protein-protein docking Benchmark 3.0 and CAPRI targets from rounds 1-19. Our results suggest that more than 50% of these globular interactions are dominated by one short linear segment at the domain interface, which provides more than half of the original interaction energy. Importantly, in many cases the derived peptides show strong energetic preference for their original binding mode independently of the context of their original domain, as we demonstrate by extensive computational peptide docking experiments. As an in-depth case study, we computationally design a candidate peptide to inhibit the EphB4-EphrinB2 interaction based on a short peptide derived from the G-H loop in EphrinB2. Altogether, we provide an elaborate framework for the in-silico selection of candidate inhibitory molecules for protein-protein interactions. Such candidate molecules can be readily subjected to wet-lab experiments and provide highly promising starting points for subsequent drug design.

London, Nir; Raveh, Barak; Movshovitz-Attias, Dana; Schueler-Furman, Ora

2010-01-01

125

Surface and Atmospheric Parameters Derived from AIRS/AMSU Data on Aqua  

NASA Technical Reports Server (NTRS)

AIRS (Atmospheric Infra-Red Sounder) and AMSU (Advanced Microwave Sounding Unit) comprise the advanced atmospheric and surface sounding system flying on the Aqua satellite launched in May 2002. Monthly mean fields derived from AIRS/AMSU data will be used to extend the climate record (1979-2002) contained in the TOVS Pathfinder Path A Data Set to further study climate variability and trends. Sample daily and monthly mean results derived from AIRS/AMSU data are presented, validated, and compared to equivalent results taken from ECMWF analyses.

Susskind, Joel

2003-01-01

126

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

PubMed Central

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

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

2014-01-01

127

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

PubMed

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

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

2014-01-01

128

User's manual for DWNWND: an interactive Gaussian plume atmospheric transport model with eight dispersion parameter options  

SciTech Connect

The most commonly used approach for estimating the atmospheric concentration and deposition of material downwind from its point of release is the Gaussian plume atmospheric dispersion model. Two of the critical parameters in this model are sigma/sub y/ and sigma/sub z/, the horizontal and vertical dispersion parameters, respectively. A number of different sets of values for sigma/sub y/ and sigma/sub z/ have been determined empirically for different release heights and meteorological and terrain conditions. The computer code DWNWND, described in this report, is an interactive implementation of the Gaussian plume model. This code allows the user to specify any one of eight different sets of the empirically determined dispersion paramters. Using the selected dispersion paramters, ground-level normalized exposure estimates are made at any specified downwind distance. Computed values may be corrected for plume depletion due to deposition and for plume settling due to gravitational fall. With this interactive code, the user chooses values for ten parameters which define the source, the dispersion and deposition process, and the sampling point. DWNWND is written in FORTRAN for execution on a PDP-10 computer, requiring less than one second of central processor unit time for each simulation.

Fields, D.E.; Miller, C.W.

1980-05-01

129

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

130

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

131

Tropical tropopause parameters derived from GPS radio occultation measurements with CHAMP  

Microsoft Academic Search

The temperature structure in the tropical upper troposphere and lower stratosphere (UTLS) region is discussed based on Global Positioning System (GPS) radio occultation (RO) data from the German CHAMP (CHAllenging Minisatellite Payload) satellite mission. Several climatologies for tropopause parameters based on radiosonde data and model analyses have been published in recent years. Both data sources suffer either from low global

T. Schmidt; J. Wickert; G. Beyerle; C. Reigber

2004-01-01

132

New Methods to Derive the Optical and Beam Parameters in Transport Channels  

Microsoft Academic Search

The standard approach to compute the optical parameters and the beam emittance in a transport channel is based on the analysis of the profiles measured by three monitors. This requires the independent measurement of the dispersion function at the monitor locations and the knowledge of the value of the beam's momentum spread. In this paper different approaches based on the

Gianluigi Arduini; Massimo Giovannozzi; K Hanke; Django Manglunki; M Martini

2000-01-01

133

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

Microsoft Academic Search

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

Jan Hafner; Stanley Q. Kidder

1999-01-01

134

Photometric parameter maps of the Moon derived from LROC WAC images  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

135

Study on interaction between plasmid DNA and berberine derivatives with aliphatic chain by fluorescence analysis.  

PubMed

In this study, the fluorescence analysis was used to reveal the interaction between berberine derivatives and plasmid DNA. The results showed that berberine (C0) and its 8-alkyl derivatives can enhance the fluorescent intensity of plasmid DNA. Compared with 8-dodecyl- (C12) and 8-hexadecyl- (C16) berberine, 8-alkylberberine with shorter alkyl group, such as 8-ethyl (C2), 8-butyl (C4), 8-hexyl (C6), and 8-octyl (C8) berberine derivatives showed higher fluorescence increasing effect. Among all compounds, C4 showed highest fluorescence increasing effect. All compounds tested obviously enhanced fluorescent intensity at the concentration of 6.25 × 10(-5) mol/L. These results suggested that berberine and its derivatives can be selectively inserted to the grooves running down the plasmid DNA helix, thus, lead to the increase of fluorescence intensity of the reaction system. Also, adding proper length of aliphatic chain to berberine could promote the interaction between DNA and berberine derivatives. The results of this study may lay some useful foundation for the development of berberine-based medicine agents. PMID:24914272

Yong, Yang; Kai, He; Bao-Shun, Zhang; Xue-Gang, Li

2014-04-01

136

Study on interaction between plasmid DNA and berberine derivatives with aliphatic chain by fluorescence analysis  

PubMed Central

In this study, the fluorescence analysis was used to reveal the interaction between berberine derivatives and plasmid DNA. The results showed that berberine (C0) and its 8-alkyl derivatives can enhance the fluorescent intensity of plasmid DNA. Compared with 8-dodecyl- (C12) and 8-hexadecyl- (C16) berberine, 8-alkylberberine with shorter alkyl group, such as 8-ethyl (C2), 8-butyl (C4), 8-hexyl (C6), and 8-octyl (C8) berberine derivatives showed higher fluorescence increasing effect. Among all compounds, C4 showed highest fluorescence increasing effect. All compounds tested obviously enhanced fluorescent intensity at the concentration of 6.25 × 10?5 mol/L. These results suggested that berberine and its derivatives can be selectively inserted to the grooves running down the plasmid DNA helix, thus, lead to the increase of fluorescence intensity of the reaction system. Also, adding proper length of aliphatic chain to berberine could promote the interaction between DNA and berberine derivatives. The results of this study may lay some useful foundation for the development of berberine-based medicine agents.

Yong, Yang; Kai, He; Bao-Shun, Zhang; Xue-Gang, LI

2014-01-01

137

On the derivation of passive 3D material parameters from 1D stress-strain data of hydrostats.  

PubMed

The present paper offers a novel equivalent-pressure approach to the derivation of isotropic passive muscle parameters from 1D stress-strain data sets. The approach aims specifically at the identification of material parameters in hydrostats, in which case the equivalent-force approach that is common for skeletal muscle generates suboptimal results. Instead, an equivalent-pressure hypothesis is formulated which provides more adequate boundary conditions for the concluding curve-fitting procedure. The choice of an appropriate constitutive description is decisive for the quality of the deduced parameter sets. Here, a Yeoh material law is chosen for the model of a squid tentacle. Parameters derived by both, equivalent-force and equivalent-pressure algorithms, are compared, illustrating the applicability limits of either. They are implemented in a finite element model of the tentacle. A prey-capture strike is simulated and compared to data from literature. The hydrostat-specific interpretation of the equivalent-pressure hypothesis is shown to match the reference very well. PMID:21696743

Winkel, Benjamin; Schleichardt, Axel

2011-07-28

138

Electromagnetic interactions of heavy ions at small impact parameters and lepton pair productions  

NASA Astrophysics Data System (ADS)

In peripheral collisions, the strong electromagnetic fields are produced since the fully stripped heavy ions moves at ultra-relativistic velocities. Lepton pairs, especially the electron-positron pairs are the result of this collisions. At the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), virtual photons produce many particles such as electron-positron pairs, heavy lepton (muons and tauons) pairs, magnetic monopoles, W-pairs, b-quark pairs and possibly the Higgs. At small impact parameters, the colliding nuclei make peripheral collisions, photon fluxes are very large and these are responsible for the multiple photonuclear interactions. Free pair productions, bound free pair productions, and nuclear Coulomb excitations are important examples of such interactions, and these processes play important roles in the beam luminosity at RHIC and LHC. Here we obtained bound free electron-positron pair production with nuclear breakup for heavy ion collisions at RHIC and LHC.

Cem Güçlü, M.; Yilmaz ?engül, M.

2011-09-01

139

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

140

Flory-huggins interaction parameters of LCP\\/thermoplastic blends measured by DSC analysis  

Microsoft Academic Search

Liquid crystalline polymer\\/polyamide 66 (LCP\\/PA66) and LCP\\/poly(butyl terephthalate) (LCP\\/PBT) blends were compounded using\\u000a a Brabender Plasticorder equipped with a mixing chamber. The LCP employed was a semi-flexible liquid crystalline copolyesteramide\\u000a based on 30 mol% of p-amino benzoic acid (ABA) and 70 mol% of poly(ethylene terephthalate) (PET). The Flory-Huggins interaction parameters (?12)\\u000a of the LCP\\/ PA66 and LCP\\/PBT blends are estimated

X. L. Xie; R. K. Y. Li; S. C. Tjong; C. Y. Tang

2002-01-01

141

Study on the interaction between gelatin and polyurethanes derived from fatty acids.  

PubMed

In this study, gelatin was blended to proprietary noncytotoxic polyurethanes (PU) derived from vegetable oils with different weight ratios, as material for the preparation of novel biomedical products. The PU/gelatin blends were characterized for their morphology through scanning electron microscopy. Mechanical and thermal properties, chemical interactions between components, degradation behavior, surface properties, cell adhesion, and bioactivity were investigated as a function of the protein content. Higher blend miscibility was observed for the amorphous PUs, derived from oleic acid. Properties of PU/gelatin films were strongly influenced by the concentration of gelatin in the films. Gelatin enhanced the hydrophilicity, bioactivity, and cell adhesion of PUs. PMID:22965488

González-Paz, R J; Lligadas, G; Ronda, J C; Galià, M; Ferreira, A M; Boccafoschi, F; Ciardelli, G; Cádiz, V

2013-04-01

142

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

NASA Astrophysics Data System (ADS)

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)4] layers to form a solid of formula unit T(ImD)2[Ni(CN)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)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.

González, M.; Lemus-Santana, A. A.; Rodríguez-Hernández, J.; Aguirre-Velez, C. I.; Knobel, M.; Reguera, E.

2013-08-01

143

Deriving aerosol parameters from absolute UV sky radiance measurements using a Brewer double spectrometer  

Microsoft Academic Search

A Brewer MKIII double spectrophotometer has been modified to measure direct sun and sky radiance from 303nm to 363nm for the purpose of measuring aerosol optical depth, Angstrom parameter, and single scattering albedo. Results from a detailed instrument calibration showed that there is a temperature dependence of 0.3% per degree Celsius, the field of view was 2.6° full width half

Alexander M. Cede; Gordon Labow; Matthew G. Kowalewski; Nickolay A. Krotkov; Oleg Dubovik

2003-01-01

144

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

145

The star cluster population of M 51. II. Age distribution and relations among the derived parameters  

Microsoft Academic Search

We use archival Hubble Space Telescope observations of broad-band images from the ultraviolet (F255W-filter) through the near infrared (NICMOS F160W-filter) to study the star cluster population of the interacting spiral galaxy M 51. We obtain age, mass, extinction, and effective radius estimates for 1152 star clusters in a region of ~7.3 × 8.1 kpc centered on the nucleus and extending

N. Bastian; M. Gieles; R. A. Scheepmaker; R. de Grijs

2005-01-01

146

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

PubMed

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

Thalberg, Kyrre; Berg, Elna; Fransson, Magnus

2012-05-10

147

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

148

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

149

Control over the parameters of THz waves interacting with semiconductor free carriers  

NASA Astrophysics Data System (ADS)

An exploration of THz range causes the necessity of dynamic control over the parameters of the radiation - modulation of its intensity, phase and polarization. In this range optical properties of semiconductors are mainly defined by the interaction of radiation with semiconductor plasma. A strong influence of the external field on parameters of a plasma of any kind, including the carrier plasma, opens possibilities for controlling parameters of THz radiation. The characteristic modulation time is defined by the carriers relaxation time (about 10-12 s), i.e. has the same order of magnitude as a THz wave period. For the calculation of an influence of an external quasi-static electric field on the parameters of the plasma and on the optical properties of the semiconductor all main mechanisms of carrier scattering and relaxation were accounted. For AIIIBV semiconductors the calculations of the response of the complex permittivity of carrier plasma on the external field were done numerically. An analysis of the reflection coefficients based on generalized Fresnel equations showed a variation of the reflection coefficient of the semiconductor under the influence of the field by dozens percent. Static parameters of semiconductors which provide a maximum modulation depth were defined. In case when an external field is a THz band field itself, the dependence of the permittivity on the intensity results in the harmonics generation. An analysis of the specific features of the generation showed an appearance of frequency resonances and a unique non-monotonic way of the dependence of the harmonic intensity on the pump wave field.

Moiseenko, E. V.; Shepelev, A. V.

2010-09-01

150

Solution structures and model membrane interactions of lactoferrampin, an antimicrobial peptide derived from bovine lactoferrin  

Microsoft Academic Search

Bovine lactoferrampin (LFampinB) has been identified as a novel antimicrobial peptide, which is derived from the N-terminal lobe of bovine lactoferrin. In this study, the solution structure of LFampinB bound to negatively charged sodium dodecyl sulphate micelles and zwitterionic dodecyl phosphocholine micelles was determined using 2-dimensional nuclear magnetic resonance (NMR) spectroscopy. The interaction between LFampinB and multilamellar phospholipid vesicles, containing

Evan F. Haney; Fanny Lau; Hans J. Vogel

2007-01-01

151

The interactions of antimicrobial peptides derived from lysozyme with model membrane systems  

Microsoft Academic Search

Two peptides, RAWVAWR-NH2 and IVSDGNGMNAWVAWR-NH2, derived from human and chicken lysozyme, respectively, exhibit antimicrobial activity. A comparison between the L-RAWVAWR, D-RAWVAWR, and the longer peptide has been carried out in membrane mimetic conditions to better understand how their interaction with lipid and detergent systems relates to the reported higher activity for the all L-peptide. Using CD and 2D 1H NMR

Howard N. Hunter; Weiguo Jing; David J. Schibli; Tony Trinh; In Yup Park; Sun Chang Kim; Hans J. Vogel

2005-01-01

152

Study of DNA interactions with cyclic chalcone derivatives by spectroscopic techniques  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

153

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

154

New Microscopic Derivation of the Interacting Boson Model and Its Applications to Exotic Nuclei  

SciTech Connect

We present a new scheme to determine the Hamiltonian of the Interacting Boson Model (IBM) microscopically, which starts from the mean-field model with Skyrme-type interactions. Surface deformations and the effects of the nuclear force are simulated in terms of bosons. By comparing Potential Energy Surface (PES) of the mean-field model with that of the IBM, the parameters of the IBM Hamiltonian can be obtained. By this method, quantum shape/phase transitions and critical-point symmetries can be reproduced. Systematic calculations on Xe and Ru isotopes shall be newly presented, which partly contain the predicted energy levels.

Nomura, K.; Shimizu, N. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Otsuka, T. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); RIKEN Nishina center, Hirosawa, Wako-shi, 351-0198 Saitama (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI (United States)

2009-08-26

155

Comparing brain tissue oxygen measurements and derived autoregulation parameters from different probes (Licox vs. Raumedic).  

PubMed

We investigated two commercially available probes for measurement of the partial pressure of brain tissue oxygen (PbrO2) and calculation of the index of brain tissue oxygen pressure reactivity (ORx) in 7 patients after aneurysmal subarachnoid hemorrhage (SAH). Simultaneous monitoring of PbrO2 using the Licox(®) probe and the multiparameter Raumedic probe (Neurovent PTO(®)), measuring PbrO2, intracranial pressure (ICP) and brain temperature (Neurovent PTO) was performed for a median of 9 days (range 7-17 days). Both probes provided stable monitoring throughout the desired period. Mean PbrO2 from Licox and Neurovent PTO was 16.1 ± 9.0 mmHg and 17.5 ± 11.9 mmHg respectively. Mean ORx was 0.35 ± 0.44 and 0.31 ± 0.43 respectively. There was a difference in the measurement of PbrO2 of -2.73 ± 10.1 mmHg (Licox - Raumedic). The difference in the two values for the calculated ORx was far smaller (0.03 ± 0.31; Licox - Raumedic) and the correlation coefficient higher than for both values of PbrO2 (0.76 for ORx vs. 0.56 for PbrO2). The calculation of the autoregulation parameter ORx seemed more independent of the measurement process than the measurement of PbrO2 itself and signifies the potential clinical importance of this parameter. PMID:22327685

Dengl, M; Jaeger, M; Renner, C; Meixensberger, J

2012-01-01

156

Prevalence of Keratoconus and Subclinical Keratoconus in Subjects with Astigmatism Using Pentacam Derived Parameters  

PubMed Central

Purpose To determine the prevalence of keratoconus (KCN) and subclinical KCN among subjects with two or more diopters (D) of astigmatism, and to compare Pentacam parameters among these subjects. Methods One hundred and twenty eight eyes of 64 subjects with astigmatism ?2D were included in the study. All subjects underwent a complete ophthalmic examination which included refraction, visual acuity measurement, slit lamp biomicroscopy, retinoscopy, fundus examination, conventional corneal topography and elevation-based topography with Pentacam. The diagnosis of KCN and subclinical KCN was made by observing clinical findings and topographic features; and confirmed by corneal thickness and elevation maps of Pentacam. Several parameters acquired from Pentacam were analyzed employing the Mann-Whitney U Test. Results Mean age of the study population was 29.9±9.8 (range 15-45) years which included 39 (60.9%) female and 25 (39.1%) male subjects. Maximum corneal power, index of vertical asymmetry, keratoconus index and elevation values were significantly higher and pachymetry was significantly thinner in eyes with clinical or subclinical KCN than normal astigmatic eyes (P< 0.05). Conclusion The current study showed that subjects with 2D or more of astigmatism who present to outpatient clinics should undergo corneal topography screening for early diagnosis of KCN even if visual acuity is not affected. Pentacam may provide more accurate information about anterior and posterior corneal anatomy especially in suspect eyes.

Serdarogullari, Huseyin; Tetikoglu, Mehmet; Karahan, Hatice; Altin, Feyza; Elcioglu, Mustafa

2013-01-01

157

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

PubMed Central

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

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

2014-01-01

158

[Fluorescent derivatives of diphtheria toxin subunit B and their interaction with Vero cells].  

PubMed

Diphtheria toxin's B subunit provides toxin interaction with its receptor on the cell surface and translocation of toxin's A subunit from endosome to cytozole of sensitive cells. Functional analogues of B subunit with fluorescent label are considered as perspective tools for studying the above mentioned processes. The aim of the work was to obtain fluorescent B subunit analogues and to detect the specificity of their interaction with Vero line cells. B subunit fluorescent analogues were obtained in two different ways. The first one was B subunit chemical conjugation with fluorescein isothiocyanate and the second one was genetic fusion of recombinant B subunit chain with enhanced green fluorescent protein chain. Specific interaction of B subunit fluorescent derivatives with Vero cells was studied by flow cytometry and confocal microscopy. Using competitive analysis it was shown that B subunit fluorescent analogues possessed different affinity for cells. The affinity of EGFP-SbB was higher than FITC-SbB. Our results indicate the possibility to use the fluorescent derivatives of B subunit as tools for identification of diphtheria toxin's receptor (HB-EGF) expression on the cell surface as well as for studying the interaction and penetration of diphtheria toxin to the cell. PMID:19877418

Kaberniuk, A A; Labyntsev, A Iu; Kolybo, D V; Oli?nyk, O S; Redchuk, T A; Korotkevych, N V; Horchev, V F; Karakhim, S O; Komisarenko, S V

2009-01-01

159

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

160

Development of the smooth orthogonal decomposition method to derive the modal parameters of vehicle suspension system  

NASA Astrophysics Data System (ADS)

In this paper, the smooth orthogonal decomposition (SOD) method is developed to the light damped systems in which the inputs are time shifted functions of one or more random processes. An example of such practical cases is the vehicle suspension system in which the random inputs due to the road roughness applied to the rear wheels are the shifted functions of the same random inputs on the front wheels with a time lag depending on the vehicle wheelbase as well as its velocity. The developed SOD method is applied to determine the natural frequencies and mode shapes of a certain vehicle suspension system and the results are compared with the true values obtained by the structural eigenvalue problem. The consistency of the results indicates that the SOD method can be applied with a high degree of accuracy to calculate the modal parameters of vibrating systems in which the system inputs are shifted functions of one or more random processes.

Rezaee, Mousa; Shaterian-Alghalandis, Vahid; Banan-Nojavani, Ali

2013-04-01

161

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

162

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

163

Bulk properties of light deformed nuclei derived from a medium-modified meson-exchange interaction  

Microsoft Academic Search

Deformed Hartree-Fock-Bogoliubov calculations for finite nuclei are carried out. As residual interaction, a Brueckner G-matrix de- rived from a meson-exchange potential is taken. Phenomenological medium modifications of the meson masses are introduced. The binding energies, radii, and deformation parameters of the Car- bon,Oxygen, Neon, and Magnesium isotope chains are found to be in good agreement with the experimental data.

F. Grummer; B. Q. Chen; Z. Y. Ma; S. Krewald

164

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

Microsoft Academic Search

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

Sébastien Biass; Costanza Bonadonna

2011-01-01

165

Herb-drug interaction prediction based on the high specific inhibition of andrographolide derivatives towards UDP-glucuronosyltransferase (UGT) 2B7.  

PubMed

Herb-drug interaction strongly limits the clinical application of herbs and drugs, and the inhibition of herbal components towards important drug-metabolizing enzymes (DMEs) has been regarded as one of the most important reasons. The present study aims to investigate the inhibition potential of andrographolide derivatives towards one of the most important phase II DMEs UDP-glucuronosyltransferases (UGTs). Recombinant UGT isoforms (except UGT1A4)-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction and UGT1A4-catalyzed trifluoperazine (TFP) glucuronidation were employed to firstly screen the andrographolide derivatives' inhibition potential. High specific inhibition of andrographolide derivatives towards UGT2B7 was observed. The inhibition type and parameters (Ki) were determined for the compounds exhibiting strong inhibition capability towards UGT2B7, and human liver microsome (HLMs)-catalyzed zidovudine (AZT) glucuronidation probe reaction was used to furtherly confirm the inhibition behavior. In combination of inhibition parameters (Ki) and in vivo concentration of andrographolide and dehydroandrographolide, the potential in vivo inhibition magnitude was predicted. Additionally, both the in vitro inhibition data and computational modeling results provide important information for the modification of andrographolide derivatives as selective inhibitors of UGT2B7. Taken together, data obtained from the present study indicated the potential herb-drug interaction between Andrographis paniculata and the drugs mainly undergoing UGT2B7-catalyzed metabolic elimination, and the andrographolide derivatives as potential candidates for the selective inhibitors of UGT2B7. PMID:24631340

Ma, Hai-Ying; Sun, Dong-Xue; Cao, Yun-Feng; Ai, Chun-Zhi; Qu, Yan-Qing; Hu, Cui-Min; Jiang, Changtao; Dong, Pei-Pei; Sun, Xiao-Yu; Hong, Mo; Tanaka, Naoki; Gonzalez, Frank J; Ma, Xiao-Chi; Fang, Zhong-Ze

2014-05-15

166

Comprehensive contrast comparison of laver cultivation area extraction using parameters derived from polarimetric synthetic aperture radar data  

NASA Astrophysics Data System (ADS)

Image contrast between extracted laver cultivation area and background water was extensively compared using various parameters that can be calculated by dual- and quad-polarization (fully polarimetric) synthetic aperture radar data. Each parameter derived from Pauli decomposition, eigenvalue analysis, coherence analysis, and four-component scattering power decomposition (4-CSPD) has distinctive characteristics and react to different backscatterers differently. Contrast comparison was made using these parameters using the L-band quad-polarization data acquired by phased-array L-band synthetic aperture radar (PALSAR) on board advanced land observing satellite (ALOS) and the X-band dual-polarization data acquired by TerraSAR-X, and experimental results showed that the contrast can be improved using multi-polarization data than using single-polarization data. It has also been found that entropy performs better among dual-polarization methods, and the surface scattering component calculated from 4-CSPD exhibits higher contrast than any other parameters from quad-polarization data.

Sugimoto, Mitsunobu; Ouchi, Kazuo; Nakamura, Yasuhiro

2013-01-01

167

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

168

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

PubMed Central

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

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

2005-01-01

169

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

170

Tuning the adsorption interactions of imidazole derivatives with specific metal cations.  

PubMed

In this work, we report a computational study of the interactions between metal cations and imidazole derivatives in the gas phase. We first performed a systematic assessment of various density functionals and basis sets for predicting the binding energies between metal cations and the imidazoles. We find that the M11L functional in combination with the 6-311++G(d,p) basis set provides the best compromise between accuracy and computational cost with our metal···imidazole complexes. We then evaluated the binding of a series of metal cations, including Li(+), Na(+), K(+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Ba(2+), Hg(2+), and Pb(2+), with several substituted imidazole derivatives. We find that electron-donating groups increase the metal-binding energy, whereas electron-withdrawing groups decrease the metal-binding energy. Furthermore, the binding energy trends can be rationalized by the hardness of the metal cations and imidazole derivatives, providing a quick way to estimate the metal···imidazole binding strength. This insight can enable efficient screening protocols for identifying effective imidazole-based solvents and membranes for metal adsorption and provide a framework for understanding metal···imidazole interactions in biological systems. PMID:24824821

Liu, Haining; Bara, Jason E; Turner, C Heath

2014-06-01

171

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

PubMed

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

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

2013-06-01

172

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

173

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

174

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

175

Key parameters in blood-surface interactions of 3D bioinspired ceramic materials.  

PubMed

Direct contact of materials with blood components may trigger numerous processes which ultimately lead to hemolysis, clot formation and recruitment of inflammatory cells. In this study, the blood-surface interactions for two inert bioinspired ceramic scaffolds obtained from natural resources; biomorphic carbon and silicon carbides (bioSiC) from different origins have been studied. The response of the blood in contact with carbon is well known, however little has been identified on the influence of their 3D porous structure. Moreover, to our knowledge, there is no reference in the literature about the hemocompatibility of biomorphic silicon carbide as a porous scaffold. The experimental results showed the surface energy to be crucial to evaluate the hemocompatibility of a material however the surface topography and material porosity are also parameters to be considered. Surface roughness modifies clot formation whereas for protein adsorption total sample porosity seems to be the key parameter to be considered for hydrophilic materials (biomorphic silicon carbides), while the size of the pores determines the hemolytic response. PMID:24907756

Díaz-Rodríguez, P; González, P; Serra, J; Landin, M

2014-08-01

176

Simultaneous determination of the interaction parameter and topological scaling features of polymers in dilute solutions  

NASA Astrophysics Data System (ADS)

The RPA equation using the Debye polymer chain scattering function has been widely used to model polymer blends of linear chains in the melt where it is safe to assume a Gaussian conformation. When chains display more complicated topologies or when chains are in dilute solution Gaussian scaling no longer applies. In some cases the Zimm double extrapolation has been used to determine the second virial coefficient and the interaction parameter under the assumption that the deviation of chain scaling from a random walk is acceptable in the low qRg region such as when light scattering is used. If it is of interest to explicitly determine the nature of chain scaling, related to topology or solvent quality, as well as to quantify the thermodynamic interaction, such as in studies of cyclic and branched chains, networks, or polymers in good solvents, there is no analytically valid scattering model for data analysis. We propose the coupling of the unified scattering function with the RPA equation to analytically model these effects. Nevertheless, some issues remain to be resolved with star polymers in particular, such as scattering from highly branched high molecular weight symmetric stars in good solvents where it appears that the Daoud-Cotton model may be appropriate but a colloidal scattering model may be more appropriate.

Rai, Durgesh; Beaucage, Gregory; Kedar, Ratkanthwar; Hadjichristidis, Nikos; Kunlun, Hong; Uhrig, David; Tsou, Andy

2013-03-01

177

Measures of maternal-fetal interaction in day-30 bovine pregnancies derived from nuclear transfer.  

PubMed

Embryonic mortality and abnormal placental morphology have been reported by most researchers studying nuclear transfer (NT), and it now is accepted that placental anomalies and poor development of cloned embryos are related. As early as day 50 of gestation, cloned bovine concepti exhibit poor structural organization of the developing placentomes. These experiments were designed to identify alterations in maternal-fetal interactions during establishment of the placentas of NT-derived embryos at day 30 of gestation. Bovine NT embryos were produced using cultured fibroblast cells from a single Hereford donor cow, and control embryos were derived from in vitro fertilization (IVF). Following in vivo culture in ligated sheep oviducts, day-8 blastocysts were transferred to synchronized recipient heifers. Tissues recovered from viable day-30 pregnancies were analyzed by real-time RT-PCR, immunohistochemistry, and quantitative histological techniques. Immunoperoxidase staining of caruncular tissue from NT- and IVF-derived pregnancies revealed no significant differences in expression of the extracellular matrix proteins, collagen type IV and laminin, or the receptor subunits, integrins alpha1 and alpha3, suggesting that altered expression of these proteins at day 30 of gestation is not a primary cause of abnormal placentome structure in cloned concepti. Percentage of binucleate cells (BNC) within the trophoblast also was similar in NT- and IVF-derived pregnancies; however, expression of the BNC-specific placental lactogen (PL) transcript was elevated in NT-derived concepti (p < 0.05). These results indicate that regulation of PL transcription was altered in cloned day-30 placental tissues, suggesting the presence of irregular fetal-maternal signaling patterns that might undermine continued development of NT-derived concepti. PMID:16390265

Hoffert, Kara A; Batchelder, Cynthia A; Bertolini, Marcelo; Moyer, Alice L; Famula, Thomas R; Anderson, Dianne L; Anderson, Gary B

2005-01-01

178

Physicochemical interaction of antitumor acridinone derivatives with DNA in view of QSAR studies.  

PubMed

The acridinone derivatives with antitumor activity and ability with respect to noncovalent DNA binding were investigated for their quantitative structure-activity relationships (QSAR). Multiple regression analysis was used to model relationships between molecular descriptors and antileukemia activity, or between molecular descriptors and DNA-duplexes stabilization. Studies were performed on molecular modeling using HyperChem and Dragon computer programs, and molecular geometry optimization using MM+ molecular mechanics and semi-empirical AM1 method. Two multiple regression equations were derived and characterized as good and with statistically significant correlations, R = 0.9384 and R = 0.8388, for quantitative structure-antitumor activity relationships and quantitative structure-ability to DNA-duplexes stabilization relationships, respectively. Moreover, hydrophobic and total molecular symmetry properties are important for antitumor activity of acridinone derivatives, and electronic and topological properties are important for physicochemical (noncovalent) DNA-duplexes stabilization of these compounds. The obtained equations can be used for prediction of acridinone derivatives' activity and their ability to noncovalent interaction with DNA which, as it was shown earlier, play important role in the antitumor mechanism of action of these compounds. PMID:22003274

Koba, Marcin; B?czek, Tomasz

2011-11-01

179

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

180

Influence of the spatial resolution of satellite-derived vegetation parameters on the biogenic Volatile Organic Compounds (VOC) emission modeling  

NASA Astrophysics Data System (ADS)

Vegetation is a natural source of Volatile Organic Compounds (VOC) that plays an important role in atmospheric chemistry. The main objective of the current study is to implement a model to quantify process-based VOC emissions from plants that focuses on the relationship between the sensitivity of VOC emission estimates to spatial resolution data, based on scientific knowledge and vegetation dynamics derived from satellite observations. The Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI) were elected to examine this issue using different resolutions of satellite-derived products: 22m from the DEIMOS-1 satellite, and 250m and 1000m provided by MODIS. The study is focused on an area of 80×80km2 in Portugal for 2011. Detailed land cover and meteorological data are also included in the emission quantification algorithm. The primary outcomes were determined using a multi-scale analysis showing spatial and temporal variations in the vegetation parameters and modeling results. The results confirm that the emissions model is highly sensitive to the spatial resolution of the satellite-derived data, resulting in about a 30% difference in total isoprene emissions for the study area.

Silveira, Carlos M. S.; Tchepel, Oxana A.

2014-03-01

181

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

182

Interaction of Salmonella Typhimurium with Dendritic Cells Derived from Pluripotent Embryonic Stem Cells  

PubMed Central

Using an in vitro differentiation protocol we isolated cells with the properties of dendritic cells (DCs) from immunologically refractive pluripotent murine embryonic stem cells (ESCs). These ES-derived dendritic cells (ESDCs) expressed cytokines and were able to present antigen to a T cell line. Infection of ESDCs with Salmonella Typhimurium stimulated the expression of immune cell markers and thousands of murine genes, many associated with the immune response. Consequently, this system provides a novel in vitro model, amenable to genetic modification, for monitoring host/pathogen interactions.

Rossi, Raffaella; Hale, Christine; Goulding, David; Andrews, Robert; Abdellah, Zarah; Fairchild, Paul J.; Dougan, Gordon

2012-01-01

183

Excited state enantiodifferentiating interactions between a chiral benzophenone derivative and nucleosides.  

PubMed

Time-resolved measurements using nanosecond laser flash photolysis have revealed significant enantiodifferentiation in the interaction between ketoprofen (a chiral benzophenone derivative) and two relevant nucleosides, namely, thymidine and 2'-deoxyguanosine. In both cases, the highest quenching rate constants have been observed for (R)-ketoprofen, the enantiomer with lower pharmacological activity. Photoproduct studies performed in the case of thymidine suggest that the enantiodifferentiating process corresponds to a Paterno-Büchi reaction, leading to the formation of oxetanes. With 2'-deoxyguanosine, the quenching is associated with an electron-transfer process monitored through the generation of a ketyl radical. PMID:16159251

Lhiaubet-Vallet, Virginie; Encinas, Susana; Miranda, Miguel A

2005-09-21

184

Aerosol, surface, and cloud optical parameters derived from airborne spectral actinic flux: measurement comparison with other methods  

NASA Astrophysics Data System (ADS)

Optical parameters of aerosols, surfaces, and clouds are essential for an accurate description of Earth’s radiative balance. We will present values for such parameters derived from spectral actinic flux measured on board the NOAA WP-3D aircraft during the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) study in April 2008. We will compare these measurements to results obtained from other instruments on board the same aircraft, such as the Solar Spectral Flux Radiometer (SSFR) for irradiance measurements and aerosol extinction and absorption measurements by cavity ring-down and Particle Soot Absorption Photometer (PSAP). Actinic flux is sensitive to these parameters and can be used to measure them directly in the atmosphere without in-situ sampling methods required. We will describe the specifics of the actinic flux measurements, show advantages and disadvantages of this measurement technique, and compare results with other techniques. Furthermore, we will compare our measurements with model calculations from radiative transfer models such as the Tropospheric Ultraviolet and Visible (TUV) radiation model, the widely used library of radiative transfer (libradtran) model, and a Monte-Carlo radiation model (GRIMALDI). Also, we will investigate satellite measurements to constrain the radiation measurements to general radiation conditions in the arctic and to compare the results to aerosol optical depth retrievals. In particular, we will show results for surface albedo of the Arctic Ocean ice surface, extinction and absorption of Arctic haze layers, and optical thickness and albedo measurements of clouds.

Stark, H.; Bierwirth, E.; Schmidt, S.; Kindel, B. C.; Pilewskie, P.; Lack, D. A.; Madronich, S.; Parrish, D. D.

2009-12-01

185

Structure of chemokine-derived antimicrobial peptide IL-8? and interaction with detergent micelles and oriented lipid bilayers  

PubMed Central

Interleukin-8? (IL-8?) is an antimicrobial peptide derived from the chemokine IL-8. Solution NMR was used to determine the atomic resolution structure of IL-8? in SDS micelles. Solid state NMR and tryptophan fluorescence were used to probe the interaction of IL-8? with model membranes. The peptide interacted differently with anionic versus purely zwitterionic micelles or bilayers. Tryptophan fluorescence demonstrated a deeper position of Trp 4 in SDS micelles and POPC/POPG bilayers compared to pure POPC bilayers, consistent with 2H order parameters, which also indicated a deeper position of the peptide in POPC/POPG bilayers compared to POPC bilayers. Paramagnetic probe data showed that IL-8? was situated roughly parallel to the SDS micelle surface, with a slight tilt that positioned the N-terminus more deeply in the micelle compared to the C-terminus. 15N solid-state NMR spectra indicated a similar, nearly parallel position for the peptide in POPC/POPG bilayers. 31P and 2H solid-state NMR demonstrated that the peptide did not induce the formation of any non-lamellar phases and did not significantly disrupt bilayer orientation in aligned model membranes composed of POPC or POPC/POPG.

Bourbigot, Sarah; Fardy, Liam; Waring, Alan J.; Yeaman, Michael R.; Booth, Valerie

2009-01-01

186

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

187

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

188

EPR spectroscopy and exchange interaction parameters in Cu(glycine) 2·H 2O  

NASA Astrophysics Data System (ADS)

EPR measurements have been performed in single crystals of Cu(glycine) 2·H 2O, at 9.7 and 33 GHz and at room temperature. this orthorhombic crystal has four chemically identical but magnetically non-equivalent copper ions per unit cell. The EPR data at both microwave frequencies show two partially resolved EPR lines for some of the field directions in the ab plane, while only a single line is observed along any direction in the other two crystallographic planes. This indicates that the four copper ions are arranged in two weakly coupled and symmetry-related subsets, each involving two non-equivalent and interacting copper sites. The decoupling of the spectra leads to g1 = 2.256(2), g2 = 2.071(2) and g3 = 2.061(2) for the principal values of the molecular g-factors. The EPR data, used in conjunction with the classical Anderson's model and the Kubo and Tomita's theory, allow to evaluate the exchange interaction parameters between the magnetically non-equivalent copper ions. The Anderson's model and the observed EPR line positions data lead to | J?/ k| = 19(3) mK for the intersubset exchange coupling. The analysis of the angular variation of the line width in terms o the Kubo and Tomita's theory, gives | J?/ k| = 21(2) mK and | J/ k| = 57(1) mK for the intersubset and intrasubset exchange couplings, respectively. These values are discussed in terms of the crystal structure of the compound and compared with the results obtained by other authors.

Martino, Débora M.; Passeggi, Mario C. G.; Calvo, Rafael; Nascimento, Otaciro R.

1996-02-01

189

Comparison of dual-echo DSC-MRI- and DCE-MRI-derived contrast agent kinetic parameters  

PubMed Central

The application of dynamic susceptibility contrast (DSC) MRI methods to assess brain tumors is often confounded by the extravasation of contrast agent (CA). Disruption of the blood–brain barrier allows CA to leak out of the vasculature leading to additional T1, T2 and T2? relaxation effects in the extravascular space, thereby affecting the signal intensity time course in a complex manner. The goal of this study is to validate a dual-echo DSC-MRI approach that separates and quantifies the T1 and T2? contributions to the acquired signal and enables the estimation of the volume transfer constant, Ktrans, and the volume fraction of the extravascular extracellular space, ?e. To test the validity of this approach, DSC-MRI- and dynamic contrast enhanced (DCE) MRI-derived Ktrans and ?e estimates were spatially compared in both 9L and C6 rat brain tumor models. A high degree of correlation (concordance correlation coefficients >0.83, Pearson's r>0.84) and agreement was found between the DSC-MRI- and DCE-MRI-derived measurements. These results indicate that dual-echo DSC-MRI can be used to simultaneously extract reliable DCE-MRI kinetic parameters in brain tumors in addition to conventional blood volume and blood flow metrics.

Quarles, C. Chad; Gore, John C.; Xu, Lei; Yankeelov, Thomas E.

2012-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

191

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

192

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

193

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

194

Coherent beam-beam tune shift of unsymmetrical beam-beam interactions with large beam-beam parameter  

SciTech Connect

Coherent beam-beam tune shift of unsymmetrical beam-beam interactions was studied experimentally and numerically in HERA, where the lepton beam has such a large beam-beam parameter (up to {xi}{sub y}=0.272) that the single-particle motion is locally unstable at the origin (closed orbit). Unlike the symmetrical case of beam-beam interactions, the ratio of the coherent beam-beam tune shift and the beam-beam parameter in this unsymmetrical case of beam-beam interactions was found to decrease monotonically with an increase of the beam-beam parameter. The results of self-consistent beam-beam simulation, the linearized Vlasov equation, and the rigid-beam model were compared with the experimental measurement. It was found that the coherent beam-beam tune shifts measured in the experiment and calculated in the simulation agree remarkably well but they are much smaller than those calculated by the linearized Vlasov equation with the single-mode approximation or the rigid-beam model. The study indicated that the single-mode approximation in the linearization of the Vlasov equation is not valid in the case of unsymmetrical beam-beam interactions. The rigid-beam model is valid only with a small beam-beam parameter in the case of unsymmetrical beam-beam interactions.

Jin Lihui; Shi Jicong; Hoffstaetter, Georg H. [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States); Department of Physics, Cornell University, Ithaca, New York 14850 (United States)

2005-03-01

195

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

196

Structural Determinates for Apolipoprotein E-Derived Peptide Interaction with the ?7 Nicotinic Acetylcholine Receptor  

PubMed Central

Neuronal nicotinic acetylcholine receptor (nAChR) signaling has been implicated in a variety of normal central nervous system (CNS) functions as well as an array of neuropathologies. Previous studies have demonstrated both neurotoxic and neuroprotective actions of peptides derived from apolipoprotein E (apoE). It has been discovered that apoE-derived peptides inhibit native and recombinant ?7-containing nAChRs, indicating a direct interaction between apoE peptides and nAChRs. To probe the structure/function interaction between ?7 nAChRs and the apoE peptide apoE141-148, experiments were conducted in Xenopus laevis oocytes expressing wild-type and mutated nAChRs. Mutation of Trp55 to alanine blocks apoE peptide-induced inhibition of acetylcholine (ACh)-mediated ?7 nAChR responses. Additional mutations at Trp55 suggest that hydrophobic interactions between the receptor and apoE141-148 are essential for inhibition of ?7 nAChR function. A mutated apoE peptide also demonstrated decreased inhibition at ?7-W55A nAChRs as well as activity-dependent inhibition of both wild-type ?7 nAChRs and ?7-W55A receptors. Finally, a three-dimensional model of the ?7 nAChR was developed based on the recently refined Torpedo marmorata nACh receptor. A structural model is proposed for the binding of apoE141-148 to the ?7 nAChR where the peptide binds at the interface between two subunits, near the ACh binding site. Similar to the functional data, the computational docking suggests the importance of hydrophobic interactions between the ?7 nAChR and the apoE peptide for inhibition of receptor function. The current data suggest a mode for apoE peptide binding that directly blocks ?7 nAChR activity and consequently may disrupt nAChR signaling.

Gay, Elaine A.; Bienstock, Rachelle J.; Lamb, Patricia W.; Yakel, Jerrel L.

2009-01-01

197

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.

2013-01-01

198

Neurotoxic mechanisms of electrophilic type-2 alkenes: soft soft interactions described by quantum mechanical parameters.  

PubMed

Conjugated Type-2 alkenes, such as acrylamide (ACR), are soft electrophiles that produce neurotoxicity by forming adducts with soft nucleophilic sulfhydryl groups on proteins. Soft-soft interactions are governed by frontier molecular orbital characteristics and can be defined by quantum mechanical parameters such as softness (sigma) and chemical potential (mu). The neurotoxic potency of ACR is likely related to the rate of adduct formation, which is reflected in values of sigma. Correspondingly, differences in mu, the ability of a nucleophile to transfer electrons to an electrophile, could determine protein targets of these chemicals. Here, sigma and mu were calculated for a series of structurally similar Type-2 alkenes and their potential sulfhydryl targets. Results show that N-ethylmaleimide, acrolein and methylvinyl ketone were softer electrophiles than methyl acrylate or ACR. Softness (sigma) was closely correlated to corresponding second-order rate constants (k(2)) for electrophile reactions with sulfhydryl groups on N-acetyl-L-cysteine (NAC). The rank order of softness was also directly related to neurotoxic potency as determined by impairment of synaptosomal function and sulfhydryl loss. Calculations of mu showed that the thiolate state of several cysteine analogs was the preferred nucleophilic target of alkene electrophiles. In addition, mu was directly related to the thiolate rate constant (k) for the reaction of the Type-2 alkenes with the cysteine compounds. Finally, in accordance with respective mu values, we found that NAC, but not N-acetyl-L-lysine, protected synaptosomes from toxicity. These findings suggest that the neurotoxicity of ACR and its conjugated alkene analogs is related to electrophilic softness and that the thiolate state of cysteine residues is the corresponding adduct target. PMID:17519395

LoPachin, Richard M; Gavin, Terrence; Geohagen, Brian C; Das, Soma

2007-08-01

199

CONTROL OF LASER RADIATION PARAMETERS: Tunable acousto-optic filters with the multiple interaction of light and sound  

NASA Astrophysics Data System (ADS)

Optical multipass schemes of the interaction of light and sound, which are promising for filtration of optical beams based on tunable acousto-optic filters, are studied. The features of operation of acousto-optic filters in the rejection and transmission regimes are considered. It is proved theoretically and confirmed experimentally that the use of multiple interaction improves the spectral and energy parameters of acousto-optic devices. The collinear and transverse geometry of acousto-optic interaction in cells based on a paratellurite crystal is studied in the double-pass, three-pass, and multipass diffraction regimes.

Voloshinov, V. B.; Magdich, L. N.; Knyazev, G. A.

2005-11-01

200

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

201

Insights into the Interactions between Maleimide Derivates and GSK3? Combining Molecular Docking and QSAR  

PubMed Central

Many protein kinase (PK) inhibitors have been reported in recent years, but only a few have been approved for clinical use. The understanding of the available molecular information using computational tools is an alternative to contribute to this process. With this in mind, we studied the binding modes of 77 maleimide derivates inside the PK glycogen synthase kinase 3 beta (GSK3?) using docking experiments. We found that the orientations that these compounds adopt inside GSK3? binding site prioritize the formation of hydrogen bond (HB) interactions between the maleimide group and the residues at the hinge region (residues Val135 and Asp133), and adopt propeller-like conformations (where the maleimide is the propeller axis and the heterocyclic substituents are two slanted blades). In addition, quantitative structure–activity relationship (QSAR) models using CoMSIA methodology were constructed to explain the trend of the GSK3? inhibitory activities for the studied compounds. We found a model to explain the structure–activity relationship of non-cyclic maleimide (NCM) derivatives (54 compounds). The best CoMSIA model (training set included 44 compounds) included steric, hydrophobic, and HB donor fields and had a good Q2 value of 0.539. It also predicted adequately the most active compounds contained in the test set. Furthermore, the analysis of the plots of the steric CoMSIA field describes the elements involved in the differential potency of the inhibitors that can be considered for the selection of suitable inhibitors.

Quesada-Romero, Luisa; Mena-Ulecia, Karel; Tiznado, William; Caballero, Julio

2014-01-01

202

Interaction of three pradimicin derivatives with divalent cations in aqueous solution  

NASA Astrophysics Data System (ADS)

This study focused on further analysis of the aggregation behavior of pradimicin derivatives and their interaction with cations in aqueous solution. BMY was compared with two other pradimicin antibiotics (T2 and FB) with the same aglycone moiety but consisting of different substitute groups. The surface tension measurement showed a clear critical micelle concentration at 1-2 mM of the BMY aqueous solution. The role of Zn 2+ in replacing the Ca 2+ was examined using 1H nuclear magnetic resonance (NMR) method. From changes in the NMR spectrum and precipitability, it was concluded that zinc ion has lower affinity and higher precipitating ability to BMY than the divalent cations of alkaline earth metal. The aggregation behavior of T2 and FB in aqueous solution was also studied using NMR method. The results suggest that the supramolecular behavior of T2 is similar to BMY whether or not Ca 2+ ions are present in solution and that there are two binding sites for calcium ions in a T2 molecule. Unlike BMY and T2, the NMR spectrum of FB does not show distinct change upon Ca 2+ addition. The interaction of pradimicin antibiotics with divalent metal ions was thought to be related to ionic electronegativity and to the amphoteric property of the antibiotics.

Hu, Mei; Ishizuka, Yasuko; Igarashi, Yasuhiro; Oki, Toshikazu; Nakanishi, Hiroshi

2000-05-01

203

A comparison of the concentration-effect relationships of midazolam for EEG-derived parameters and saccadic peak velocity.  

PubMed Central

1. Concentration-effect relationships of midazolam were assessed in an open study in six healthy volunteers. Saccadic eye movements and EEG parameters derived by fast Fourier transform (FFT) and aperiodic analysis (AP) were used to quantify drug effects. 2. Midazolam was infused at a rate of 0.6 mg kg-1 h-1 for a maximum of 15 min. Hypnotic effects were avoided by terminating infusions when subjects could no longer perform the eye movement test properly. 3. Wake-sleep transitions could be recognized through frequent observation of eye movements. The dose needed to reach maximum conscious sedation averaged 0.10 mg kg-1, ranging from 0.06 to 0.13 mg kg-1. 4. Sigmoidal concentration-effect relationships were found for EEG beta-amplitudes in five of six subjects, with average EC50 values (+/- s.d.) of 120 +/- 54 ng ml-1 for FFT and 104 +/- 40 ng ml-1 for AP. For the 'total number of waves' in the beta frequency range (AP) an average (n = 6) EC50 of 63 +/- 37 ng ml-1 was found. Changes in EEG alpha-amplitudes were found in three subjects, resulting in an average EC50 value of 55 +/- 32 ng ml-1. 5. For saccadic peak velocity (PV) concentration-effect relationships were linear in five subjects and sigmoidal in one. The maximal measured decrease in PV averaged -44 +/- 9%. 6. The differences in concentration-effect relationships for various effect parameters call for further studies with emphasis on the external validity and reproducibility of data. In such studies the dose needed to reach wake-sleep transition may be used as a relevant clinical end-point.

Van Steveninck, A L; Mandema, J W; Tuk, B; Van Dijk, J G; Schoemaker, H C; Danhof, M; Cohen, A F

1993-01-01

204

A comparison of the concentration-effect relationships of midazolam for EEG-derived parameters and saccadic peak velocity.  

PubMed

1. Concentration-effect relationships of midazolam were assessed in an open study in six healthy volunteers. Saccadic eye movements and EEG parameters derived by fast Fourier transform (FFT) and aperiodic analysis (AP) were used to quantify drug effects. 2. Midazolam was infused at a rate of 0.6 mg kg-1 h-1 for a maximum of 15 min. Hypnotic effects were avoided by terminating infusions when subjects could no longer perform the eye movement test properly. 3. Wake-sleep transitions could be recognized through frequent observation of eye movements. The dose needed to reach maximum conscious sedation averaged 0.10 mg kg-1, ranging from 0.06 to 0.13 mg kg-1. 4. Sigmoidal concentration-effect relationships were found for EEG beta-amplitudes in five of six subjects, with average EC50 values (+/- s.d.) of 120 +/- 54 ng ml-1 for FFT and 104 +/- 40 ng ml-1 for AP. For the 'total number of waves' in the beta frequency range (AP) an average (n = 6) EC50 of 63 +/- 37 ng ml-1 was found. Changes in EEG alpha-amplitudes were found in three subjects, resulting in an average EC50 value of 55 +/- 32 ng ml-1. 5. For saccadic peak velocity (PV) concentration-effect relationships were linear in five subjects and sigmoidal in one. The maximal measured decrease in PV averaged -44 +/- 9%. 6. The differences in concentration-effect relationships for various effect parameters call for further studies with emphasis on the external validity and reproducibility of data. In such studies the dose needed to reach wake-sleep transition may be used as a relevant clinical end-point. PMID:8398578

Van Steveninck, A L; Mandema, J W; Tuk, B; Van Dijk, J G; Schoemaker, H C; Danhof, M; Cohen, A F

1993-08-01

205

A methodology for determining interactions in probabilistic safety assessment models by varying one parameter at a time.  

PubMed

In risk analysis problems, the decision-making process is supported by the utilization of quantitative models. Assessing the relevance of interactions is an essential information in the interpretation of model results. By such knowledge, analysts and decisionmakers are able to understand whether risk is apportioned by individual factor contributions or by their joint action. However, models are oftentimes large, requiring a high number of input parameters, and complex, with individual model runs being time consuming. Computational complexity leads analysts to utilize one-parameter-at-a-time sensitivity methods, which prevent one from assessing interactions. In this work, we illustrate a methodology to quantify interactions in probabilistic safety assessment (PSA) models by varying one parameter at a time. The method is based on a property of the functional ANOVA decomposition of a finite change that allows to exactly determine the relevance of factors when considered individually or together with their interactions with all other factors. A set of test cases illustrates the technique. We apply the methodology to the analysis of the core damage frequency of the large loss of coolant accident of a nuclear reactor. Numerical results reveal the nonadditive model structure, allow to quantify the relevance of interactions, and to identify the direction of change (increase or decrease in risk) implied by individual factor variations and by their cooperation. PMID:20199656

Borgonovo, Emanuele

2010-03-01

206

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

207

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

PubMed Central

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

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

2014-01-01

208

Interactive 3-D Immersive Visualization for Analysis of Large Multi-Parameter Atmospheric Data Sets  

NASA Astrophysics Data System (ADS)

Significant improvements in the ability of atmospheric chemistry models to predict the transport and production of atmospheric constituents on regional and global scales have been realized over the past decade. Concurrent with the model improvements, has been an increase in the size and complexity of atmospheric observational data sets. As a result, the challenge to provide efficient and realistic visualization of atmospheric data "products" has increased dramatically. Over the past several years, personnel from the Atmospheric Sciences Data Center (ASDC) at NASA's Langley Research Center have explored the merits of visualizing atmospheric data products using interactive, immersive visualization hardware and software. As part of this activity, the Virtual Global Explorer and Observatory (vGeo) software, developed by VRCO, Inc., has been utilized to support the visual analysis of large multivariate data sets. The vGeo software provides an environment in which the user can create, view, navigate, and interact with data, models, and images in an immersive 3-D environment. The vGeo visualization capability was employed during the March/April 2001, NASA Global Tropospheric Experiment Transport and Chemical Evolution over the Pacific (TRACE-P) mission [(GTE) http://www-gte.larc.nasa.gov] to support day-to-day flight-planning activities through the creation of virtual 3-D worlds containing modeled data and proposed aircraft flight paths. The GTE, a major activity within NASA's Earth Science Enterprise, is primarily an aircraft-based measurement program, supplemented by ground-based measurements and satellite observations, focused on understanding the impact of human activity on the global troposphere. The TRACE-P is the most recent campaign conducted by GTE and was deployed to Hong Kong and then to the Yokota Airbase, Japan. TRACE-P is the third in a series of GTE field campaigns in the northwestern Pacific region to understand the chemical composition of air masses emerging from the Asian Continent and their impact on the region. Since completing the field deployment phase of TRACE-P, the 3-D visualization capability has been used as a tool to combine and visually analyze TRACE-P data from multiple sources (e.g. model, airborne and ground based measurements, ozone sondes, and satellite observations). This capability to merge measurements into model data fields in a virtual 3-D world is perhaps the most exciting aspect of this new visualization capability. This allows for a more realistic contextual representation of the model/measurement results. The measured parameters along specific flights (of typical duration of 8 hrs) along with supporting ancillary measurements provide the "real" representation of the atmosphere at that specific point in time and space. The models provide the time evolution, and three-dimensional structure during the measurement period. When these are merged together the context of the observations is documented, and model predictions can be validated and/or improved. Specific TRACE-P case studies will be presented showing results from global and regional models coupled with airborne measurements for which the influence of transport on the spatial distribution of species measured on the aircraft was more clearly discerned within the 3-D environment than from conventional visualization techniques.

Frenzer, J. B.; Hoell, J. M.; Holdzkom, J. J.; Jacob, D.; Fuelberg, H.; Avery, M.; Carmichael, G.; Hopkins, D. L.

2001-12-01

209

Computation, validation and sensitivity of the DTM-derived geomorphic parameters: the case of Stream-Length Gradient Index  

NASA Astrophysics Data System (ADS)

Quantitative geomorphic analysis from DTMs has become a common procedure for creating and analysing geo-thematic maps. Nevertheless, it is often neglected that the accuracy of interpretations generally depends on the accuracy of the DTMs itself (i.e., both the ground resolution and interpolation method). In the case of the DTM-derived quantitative geomorphic indices different open-questions are still the object of a suggestive debate. One of the crucial questions is the objective identification/characterization of processes and landforms responsible for anomalous values of the parameter analysed; particularly, in those cases where either the same process can result in different anomalies or the same anomalous value can be related to different processes/landforms. In this frame, our work is aimed at providing a new geostatistical methodology to validate the computation goodness of the geomorphic indices from DTMs and to interpret the anomalous values in their spatial distribution. We applied the proposed methodology to the computation and spatial analysis of the DTM-derived Stream-Length Gradient Index (SL Index). Since the SL Index is a proxy of the Stream-Power per Unit Length and is proportional to the total stream-power available at a particular channel reach, it is very sensitive to changes in river gradient and represents a practical tool to highlight perturbations along the longitudinal profiles. In addition to the known relationship between rock resistance and SL Index, the latter may be used to detect the surface effects of fault activity through anomalously high index values on a specific rock type. Recently, some researches outlined that in small river basins extreme values of the SL Index seem to reflect the topographic fingerprint of slope failures directly reaching the stream channels. In this work we created a statistical, well-constrained SL Index map within the Upper Tena river valley, which occupies approximately 47 km2 in the mountainous sector of the central Spanish Pyrenees. The procedure proposed here is aimed at distinguishing objectively the averaged response of the SL Index values to lithology, fault displacements and slope failures. As for statistical interpolation of DTM-derived SL Index values, we proceeded in two steps: 1) computation of the experimental variogram and its best-related theoretic fit that took also into account anisotropies of the river patterns; this latter was used in the second interpolation procedure; 2) statistical validation of different interpolators (i.e., O-Kriging, U-Kriging, IDW, NeN, TLI) basing on the leave-one-out cross-validation. Finally, once obtained the SL Index map, we applied a map filtering using the representative "range-values" (RV) for all processes in order to distinguish the different topographic fingerprints of lithology, fault displacements and slope failures. Encouraging results suggest the goodness of the proposed methodology that validates at the same time both the computation and the spatial analysis of a DTM-derived quantitative geomorphic index. Moreover, we have confirmed the sensitivity of the SL Index, calculated from DTMs with different spatial resolution, to detect slope failures within mountainous small river basins.

Della Seta, M.; Galve, J. P.; Piacentini, D.; Troiani, F.

2012-04-01

210

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

PubMed Central

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

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

2013-01-01

211

Restoration of the continuous phase transition induced by frozen disorder in systems with two interacting order parameters  

NASA Astrophysics Data System (ADS)

A model which in the thermodynamic limit calculates the partition function exactly is used to study the phase transitions of systems with two interacting order parameters coupled to their respective random fields. An ordered phase is always unstable for the spatial range d?4 when both random fields are present. A continuous phase transition is possible when only one of the random fields is nonzero. For this case, a diagram of the equilibrium order parameter as a function of temperature for three different strengths of the random field is constructed. The critical temperature decreases with increasing randomness. The slope of the order parameter becomes steeper as the random field decreases and diverges as the randomness vanishes. These results can be contrasted with pure systems of coupled parameters where a fluctuation-induced first-order transition occurs.

Nicolaides, D.; Lisyansky, A. A.

2004-08-01

212

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

213

Effects of muscle model parameter dispersion and multi-loop segmental interaction on the neuromuscular system performance.  

PubMed

The effects of parameter dispersion among motor units on the neuromuscular system performance as well as interaction between muscle segments and spinal cord mechanisms are investigated. Elementary components of the system are modeled to simulate with simple models their input-output characteristics. A leaky SS-IPFM encoder with a time-dependent threshold simulates the motor-neuron encoding characteristics. An amplitude and time dependent nonlinear model represent the motor unit mechanical output to neuronal input relationship. The dispersion of parameters in the components of the whole muscle control model is investigated in the open loop mode. It is shown that the dispersion of parameters in the multi-efferent channels converging on a common tendon provides a spatial filtration generating a smoother muscle force in addition to extending the linear dynamic range compared to a similar system having identical motor units. Muscle segmental interaction is investigated in this distributed model by closing the loop through a coupling matrix, representing afferent-motorneuron interaction on the spinal cord level. A diagonal matrix represents no segmental interaction and a uniform matrix represents a uniform interaction between segments through the muscle spindles and Golgi tendon feedback elements. The close loop simulation studied shows that (a). The type of segmental interaction has little effect on the overall system performance, i.e., range of linerity and stability, which is the result of having a muscle system with a large number of motor units. (b) There are only minor differences in results between the uniform and normal parameter distributions tested. (c) A loop gain of 4 divided by 8 in the distributed model can provide linearity through the full physiological force range. (d) Type of segmental interaction has significant effects on the individual segment. A uniform matrix provides a more stable segment due to the spatial filtration resulting from the segmental interaction, while the diagonal noninteracting matrix shows instabilities on the local segmental level despite global stability. The more realistic exponentially decaying spatial interaction matrix yields both global neuromuscular and local segmental stability with the same linear dynamic range generated with the uniform or diagonal matrices. PMID:6626592

Inbar, G F; Ginat, T

1983-01-01

214

Parametrization of free ion levels of four isoelectronic 4f2 systems: Insights into configuration interaction parameters  

NASA Astrophysics Data System (ADS)

The experimental free ion 4f2 energy level data sets comprising 12 or 13 J-multiplets of La+, Ce2+, Pr3+ and Nd4+ have been fitted by a semiempirical atomic Hamiltonian comprising 8, 10, or 12 freely-varying parameters. The root mean square errors were 16.1, 1.3, 0.3 and 0.3 cm-1, respectively for fits with 10 parameters. The fitted inter-electronic repulsion and magnetic parameters vary linearly with ionic charge, i, but better linear fits are obtained with (4-i)2, although the reason is unclear at present. The two-body configuration interaction parameters ? and ? exhibit a linear relation with [?E(bc)]-1, where ?E(bc) is the energy difference between the 4f2 barycentre and that of the interacting configuration, namely 4f6p for La+, Ce2+, and Pr3+, and 5p54f3 for Nd4+. The linear fit provides the rationale for the negative value of ? for the case of La+, where the interacting configuration is located below 4f2.

Yeung, Yau Yuen; Tanner, Peter A.

2013-12-01

215

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

216

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

SciTech Connect

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

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

2008-06-15

217

Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER  

NASA Astrophysics Data System (ADS)

Thanks to their large angular dimension and brightness, red giants and supergiants are privileged targets for optical long-baseline interferometers. 16 red giants and supergiants have been observed with the VLTI/AMBER facility over a 2-year period, at medium spectral resolution (R=1500) in the K band. The limb-darkened angular diameters are derived from fits of stellar atmospheric models on the visibility and the triple product data. The angular diameters do not show any significant temporal variation, except for one target: TX Psc, which shows a variation of 4 per cent using visibility data. For the eight targets previously measured by long-baseline interferometry (LBI) in the same spectral range, the difference between our diameters and the literature values is less than 5 per cent, except for TX Psc, which shows a difference of 11 per cent. For the eight other targets, the present angular diameters are the first measured from LBI. Angular diameters are then used to determine several fundamental stellar parameters, and to locate these targets in the Hertzsprung-Russell diagram (HRD). Except for the enigmatic Tc-poor low-mass carbon star W Ori, the location of Tc-rich stars in the HRD matches remarkably well the thermally-pulsating asymptotic giant branch, as it is predicted by the stellar evolution models. For pulsating stars with periods available, we compute the pulsation constant and locate the stars along the various sequences in the period-luminosity diagram. We confirm the increase in mass along the pulsation sequences, as predicted by theory, except for W Ori which, despite being less massive, appears to have a longer period than T Cet along the first-overtone sequence.

Cruzalèbes, P.; Jorissen, A.; Rabbia, Y.; Sacuto, S.; Chiavassa, A.; Pasquato, E.; Plez, B.; Eriksson, K.; Spang, A.; Chesneau, O.

2013-09-01

218

Asymmetry parameters in the lower troposphere derived from aircraft measurements of aerosol scattering coefficients over tropical India  

NASA Astrophysics Data System (ADS)

Aerosol scattering coefficients (total ?sca and backscatter ?backsca) are measured on board an aircraft using an integrating nephelometer at 450, 550, and 700 nm in the 0 to 3000-m region over four locations in India in an air campaign held during March-May 2006. ?sca is a factor of two higher in the east (Bhubaneshwar, Chennai) than in the west (Trivandrum, Goa). ?sca is about 5-10 × 10-5 m-1 over Bhubaneshwar and Chennai. ?backsca is about an order of magnitude lower than ?sca. Seven-day air back trajectory analysis indicate that air masses originating from arid/semiraid regions, continents, and marine regions are found to influence the aerosol characteristics, in addition to local urban sources. No elevated aerosol layers are seen during the campaign. b, the aerosol backscatter fraction, is greater than 0.13 in the lower troposphere. The columnar mean Ångström exponent (?) is >1.75. Asymmetry parameter g profiles are derived for the first time over India in the lower troposphere, using the relation between b and g. 550-nm g corresponding to 30% RH is in the 0.3-0.6 range over India. Higher b, higher ?, and lower g values over these locations suggest the dominance of submicron aerosols during the campaign. Scattering aerosols corrected to 30% RH in the 0 to 3000-m altitude region contribute about 20-35% to MODIS aerosol optical depths (AODs). The variation in the contribution of scattering aerosols to AODs highlights the spatial and vertical differences in aerosol properties.

Ramachandran, S.; Rajesh, T. A.

2008-08-01

219

The Molecular Weight and Composition Dependence of Measured Flory-Huggins Interaction Parameters for Blends of Model Polyolefins  

NASA Astrophysics Data System (ADS)

The thermodynamics of binary blends of model polyolefins (deuterated polybutadiene and polyisobutylene) was studied using small angle neutron scattering (SANS) and small angle light scattering (SALS). SANS experiments on single phase blends reveal that the Flory-Huggins interaction parameter, chi, for this system depends on both blend composition and component molecular weights. This is in contrast to numerous previous studies on thermodynamics of polymer blends where chi is reported to be independent of molecular weight. The phase separation temperatures of our blends, determined by SALS and SANS, will be compared to predictions based on the measured chi parameters.

Nedoma, Alisyn; Robertson, Megan; Wanakule, Nisita; Balsara, Nitash

2008-03-01

220

Interactions of a platinum-modified perylene derivative with the human telomeric G-quadruplex.  

PubMed

The interactions of a newly synthesized platinum-modified perylene derivative, compound 7 ([{Pt(dien)}(2)(?-4-S,S')](NO(3))(4) (dien = diethylenetriamine, 4 = N,N'-bis(1-(2-aminoethyl)-1,3-dimethylthiourea)-3,4,9,10-perylenetetracarboxylic acid diimide), with the human telomeric repeat were studied using various model oligo(deoxy)ribonucleotides to mimic the polymorphic nature of the telomeric G-quadruplex. UV/visible spectroscopy, CD spectropolarimetry, electrospray mass spectrometry (ES-MS), and isothermal titration calorimetry (ITC) were used to demonstrate that compound 7 selectively recognizes the antiparallel form of the unimolecular telomeric G-quadruplex formed by the sequence d(TTAGGG)(4) (dG-24), to which it binds with a 2:1 stoichiometry and nanomolar affinity. Compared with telomeric DNA, the first binding event of compound 7 in titrations with the RNA quadruplex formed by r(UUAGGG)(4) (rG-24) is 1 order of magnitude weaker. Compound 7 does not induce the antiparallel G-quadruplex RNA, which invariably exists in a parallel form and dimerizes in solution. On the basis of the cumulative experimental data, two distinct mechanisms are proposed for the recognition of G-quadruplex DNA and RNA by compound 7. Potential biomedical and biochemical applications of the platinum-perylene technology are discussed. PMID:21999566

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

2011-11-24

221

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

PubMed

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

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

2014-04-25

222

User's manual for DWNWND: an interactive Gaussian plume atmospheric transport model with eight dispersion parameter options  

Microsoft Academic Search

The most commonly used approach for estimating the atmospheric concentration and deposition of material downwind from its point of release is the Gaussian plume atmospheric dispersion model. Two of the critical parameters in this model are sigma\\/sub y\\/ and sigma\\/sub z\\/, the horizontal and vertical dispersion parameters, respectively. A number of different sets of values for sigma\\/sub y\\/ and sigma\\/sub

D. E. Fields; C. W. Miller

1980-01-01

223

Interaction of several mono- and dihydroxybenzene derivatives of various depigmenting potencies with L-3,4-dihydroxyphenylalanine-melanin.  

PubMed

Certain mono- and dihydroxybenzene derivatives cause depigmentation of skin and hair, and appear to be selectively cytotoxic for melanized pigment cells. As direct physical and/or chemical interaction between depigmenter (DP) and pigment melanin may play a role in depigmentation, we have carried out preliminary studies in model systems where such interactions may easily be separated from effects due to tyrosinase, melanosomal proteins, and other components. We have used synthetic L-3,4-hydroxyphenylalanine (L-DOPA)-melanin as a protein-free model pigment and potassium ferricyanide as a model electron acceptor. Compounds studied were catechol, 4-t-butylcatechol, 4-methylcatechol, 3,4-dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenylacetic acid, hydroquinone, 4-methoxyphenol, 4-t-butylphenol, and 2,6, di-t-butyl-4-methylphenol (BHT) in 0.1 M phosphate buffer, pH 7.4. These compounds vary widely in their ability to depigment hair and skin. Ferricyanide reduction by DP in the presence and absence of melanin was monitored spectrophotometrically. The sparingly soluble BHT and 4-t-butylphenol did not reduce ferricyanide in the absence or presence of melanin. For the other compounds, kinetic analysis demonstrated direct interaction between each DP and melanin. Except for dihydroxyphenylacetic acid, reduction kinetics were consistent with a mechanism involving noninteractive binding of both DP and ferricyanide to melanin prior to coupled electron transfer through the melanin backbone. Kinetic analysis afforded KB, a thermodynamic constant (M-1) for DP-melanin binding, and k', a rate parameter (M s-1) for electron transfer. A dimensionless enhancement factor (EF) was defined as k'KB/ks, with ks a pseudo-first-order constant (s-1) for ferricyanide reduction in the absence of melanin. Depending on the reductant, melanin either retards (EF less than 1) or accelerates (EF greater than 1) the rate of ferricyanide reduction. There appears to be a direct relationship between EF and depigmenting potency. There is no relationship between depigmenting power and the ability per se of the DP to bind to melanin or to reduce ferricyanide. PMID:3080956

Menter, J M; Willis, I

1986-02-01

224

New approach for the studies of physicochemical parameters of interaction of Triton X-100 with cationic surfactants  

Microsoft Academic Search

The interaction of cationic surfactants (alkyltrimethylammonium bromide) with Triton X-100 (p-(1,1,3,3-tetramethylbutyl) poly (oxyethylene)) as nonionic surfactant has been investigated using potentiometeric and surface tension techniques. New methods have been used to evaluate the values of physicochemical parameters, concentration of free monomer of ionic and nonionic surfactants, degree of dissociation of ionic surfactant and the mole fraction of surfactants in mixed

H. Gharibi; B. M. Razavizadeh; M. Hashemianzaheh

2000-01-01

225

An experimentally derived confidence score for binary protein-protein interactions  

PubMed Central

Information on protein-protein interactions is of central importance for many areas of biomedical research. Currently no method exists to systematically and experimentally assess the quality of individual interactions reported in interaction mapping experiments. To provide a standardized confidence-scoring method that can be applied to tens of thousands of protein interactions we have developed an interaction tool-kit consisting of four complementary high-throughput (HT) protein interaction assays. These assays were benchmarked against positive and random reference sets (PRS and RRS) consisting of well documented human interaction pairs and randomly chosen protein pairs, respectively. A logistic regression model was trained using the PRS/RRS data to combine the assay outputs and calculate the probability that any novel interaction pair is a true biophysical interaction once it has been tested in the tool-kit. This general approach will allow a systematic and empirical assignment of confidence scores to all individual protein-protein interactions in interactome networks.

Braun, Pascal; Tasan, Murat; Dreze, Matija; Barrios-Rodiles, Miriam; Lemmens, Irma; Yu, Haiyuan; Sahalie, Julie M; Murray, Ryan R; Roncari, Luba; de Smet, Anne-Sophie; Venkatesan, Kavitha; Rual, Jean-Francois; Cusick, Michael E; Pawson, Tony; Hill, David E; Tavernier, Jan; Wrana, Jeffrey L; Roth, Frederick P; Vidal, Marc

2010-01-01

226

Path-integral solution for a two-dimensional model with axial-vector-current--pseudoscalar derivative interaction  

SciTech Connect

We study a two-dimensional quantum field model with axial-vector-current--pseudoscalar derivative interaction using path-integral methods. We construct an effective Lagrangian by performing a chiral change in the fermionic variables leading to an exact solution of the model.

Botelho, L.C.L.

1985-03-15

227

Characteristic parameters of superconductor-coolant interaction including high Tc current density limits  

NASA Technical Reports Server (NTRS)

In the area of basic mechanisms of helium heat transfer and related influence on super-conducting magnet stability, thermal boundary conditions are important constraints. Characteristic lengths are considered along with other parameters of the superconducting composite-coolant system. Based on helium temperature range developments, limiting critical current densities are assessed at low fields for high transition temperature superconductors.

Frederking, T. H. K.

1989-01-01

228

Interaction Between Geometric Parameters and Output Waveforms in High-Power Quarter-Wave Oscillators  

Microsoft Academic Search

Quarter-wave switched oscillators (SWOs) are an important technology for the generation of high-power mesoband waveforms. The operation of these SWOs has been discussed for the past several years, but a detailed discussion of the design of these sources for particular waveforms has been lacking. In this paper, we relate several important parameters such as gap spacing, oscillator shape, and antenna

Miena Armanious; J. Scott Tyo; Michael C. Skipper; Michael D. Abdalla; William D. Prather; Julie E. Lawrance

2010-01-01

229

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

230

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

231

Modeling of the processes of laser-nanoparticle interaction taking into account temperature dependences of parameters  

Microsoft Academic Search

Absorption, electron-phonon coupling and heating of nanoparticles (NPs) under action of short laser pulses on NPs and their cooling after the end of laser action usually has nonlinear character. Nonlinear electron-phonon coupling under action of pico- and femtosecond pulses on metal NPs depends on electron and lattice parameters. Optical (absorption, scattering, extinction) and thermo-physical (coefficient of thermal conductivity, heat capacity,

V. K. Pustovalov

2011-01-01

232

Modeling of the processes of laser-nanoparticle interaction taking into account temperature dependences of parameters  

Microsoft Academic Search

Absorption, electron-phonon coupling and heating of nanoparticles (NPs) under action of short laser pulses on NPs and their\\u000a cooling after the end of laser action usually has nonlinear character. Nonlinear electron-phonon coupling under action of\\u000a pico- and femtosecond pulses on metal NPs depends on electron and lattice parameters. Optical (absorption, scattering, extinction)\\u000a and thermo-physical (coefficient of thermal conductivity, heat capacity,

V. K. Pustovalov

2011-01-01

233

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.

2014-06-01

234

Interactive effect of combined exposure to glycol ethers and alcohols on toxicodynamic and toxicokinetic parameters  

Microsoft Academic Search

Ethylene glycol monomethyl ether (EGME) exhibits testicular toxicity and ethylene glycol monobutyl ether (EGBE) is a solvent\\u000a with haemolytic effects in rats. The study of the interaction of two glycol ethers (EGME and EGBE) and three alcohols (ethanol,\\u000a n-propanol and n-butanol, 10 or 30?mmol\\/kg), orally co-administered in male rats, was carried out from a toxicodynamic and toxicokinetic point\\u000a of view.

G. Morel; A. M. Lambert; B. Rieger; I. Subra

1996-01-01

235

Disentangling fluxes of energy and matter in plasma-surface interactions: Effect of process parameters  

Microsoft Academic Search

The possibility to discriminate between the relative importance of the fluxes of energy and matter in plasma-surface interaction is demonstrated by the energy flux measurements in low-temperature plasmas ignited by the radio frequency discharge (power and pressure ranges 50-250 W and 8-11.5 Pa) in Ar, Ar+H2, and Ar+H2+CH4 gas mixtures typically used in nanoscale synthesis and processing of silicon- and

M. Wolter; I. Levchenko; H. Kersten; S. Kumar; K. Ostrikov

2010-01-01

236

Numerical simulations of the atmospheric and land conditions over the Jinta oasis in northwestern China with satellite-derived land surface parameters  

Microsoft Academic Search

Mesoscale meteorological modeling is an important tool to help understand the energy budget of the oasis, while some of its initial field data are rough limited to describe the atmosphere and land conditions over a small oasis. Local factors including land surface parameters and their interaction with the atmosphere play a dominant role in the local circulation. Therefore, in this

Xianhong Meng; Shihua Lü; Tangtang Zhang; Jüxin Guo; Yanhong Gao; Yan Bao; Lijuan Wen; Siqiong Luo; Yuanpu Liu

2009-01-01

237

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

238

Classical-field approximation for cold weakly interacting bosons without free parameters  

NASA Astrophysics Data System (ADS)

The classical-field approximation to cold weakly interacting bosons allows for a unified treatment of condensed and uncondensed parts of the system. Until now, however, the quantitative predictions were limited by a dependence of the results on a grid chosen for numerical implementation of the method. In this paper, we propose replacing this unphysical ambiguity by an additional postulate: the temperature of the gas at thermal equilibrium should be the same as that of an ideal Bose gas with the same fraction of condensed atoms. As it turns out, with this additional assumption, nearly all atoms are within the classical fields, thus the method applies to the whole system.

Zawitkowski, ?ukasz; Brewczyk, Miros?aw; Gajda, Mariusz; Rz??ewski, Kazimierz

2004-09-01

239

An experimentally derived confidence score for binary protein-protein interactions.  

PubMed

Information on protein-protein interactions is of central importance for many areas of biomedical research. At present no method exists to systematically and experimentally assess the quality of individual interactions reported in interaction mapping experiments. To provide a standardized confidence-scoring method that can be applied to tens of thousands of protein interactions, we have developed an interaction tool kit consisting of four complementary, high-throughput protein interaction assays. We benchmarked these assays against positive and random reference sets consisting of well documented pairs of interacting human proteins and randomly chosen protein pairs, respectively. A logistic regression model was trained using the data from these reference sets to combine the assay outputs and calculate the probability that any newly identified interaction pair is a true biophysical interaction once it has been tested in the tool kit. This general approach will allow a systematic and empirical assignment of confidence scores to all individual protein-protein interactions in interactome networks. PMID:19060903

Braun, Pascal; Tasan, Murat; Dreze, Matija; Barrios-Rodiles, Miriam; Lemmens, Irma; Yu, Haiyuan; Sahalie, Julie M; Murray, Ryan R; Roncari, Luba; de Smet, Anne-Sophie; Venkatesan, Kavitha; Rual, Jean-François; Vandenhaute, Jean; Cusick, Michael E; Pawson, Tony; Hill, David E; Tavernier, Jan; Wrana, Jeffrey L; Roth, Frederick P; Vidal, Marc

2009-01-01

240

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

PubMed Central

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

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

2014-01-01

241

The double Caldeira-Leggett model: Derivation and solutions of the master equations, reservoir-induced interactions and decoherence  

NASA Astrophysics Data System (ADS)

In this paper we analyze the double Caldeira-Leggett model: the path integral approach to two interacting dissipative harmonic oscillators. Assuming a general form of the interaction between the oscillators, we consider two different situations: (i) when each oscillator is coupled to its own reservoir, and (ii) when both oscillators are coupled to a common reservoir. After deriving and solving the master equation for each case, we analyze the decoherence process of particular entanglements in the positional space of both oscillators. To analyze the decoherence mechanism we have derived a general decay function, for the off-diagonal peaks of the density matrix, which applies both to common and separate reservoirs. We have also identified the expected interaction between the two dissipative oscillators induced by their common reservoir. Such a reservoir-induced interaction, which gives rise to interesting collective damping effects, such as the emergence of relaxation- and decoherence-free subspaces, is shown to be blurred by the high-temperature regime considered in this study. However, we find that different interactions between the dissipative oscillators, described by rotating or counter-rotating terms, result in different decay rates for the interference terms of the density matrix.

Cacheffo, A.; Moussa, M. H. Y.; de Ponte, M. A.

2010-06-01

242

Theoretical investigations of the C-H⋯N interactions and molecular electrostatic potentials: aza derivatives of cubane  

NASA Astrophysics Data System (ADS)

Weak C-H⋯N interactions, which are electrostatic in nature, in a series of aza derivatives of cubane, (CH) 8 - ?N ? ( ? = 1-7) have been investigated by employing the ab initio and hybrid density functional methods. The characteristics of interactions have been analyzed using the topography of the molecular electrostatic potential, which reveal shallow minima near nitrogen on encompassing from the lowest energy isomers of azacubane to heptaazacubane. From the natural bond orbital analysis it has been shown that nitrogen lone pair localization increases on encompassing from aza to heptaazacubane. Consequent C-H stretching frequencies, particularly their red and blue shifts, have been discussed.

Dhumal, Nilesh R.; Gejji, Shridhar P.

2004-10-01

243

Mass spectrometric determination of ternary interaction parameters of liquid Cu-In-Sn alloy  

NASA Astrophysics Data System (ADS)

The vaporisation of a liquid Cu-In-Sn system has been investigated between 1273 and 1473 K using Knudsen effusion mass spectrometry (KEMS) and the data obtained fitted to a Redlich-Kister sub-regular solution model. We examined 23 different compositions at four fixed indium concentrations: xIn = 0.20, 0.25, 0.29, 0.30 and 0.40 and evaluate the thermodynamic activities of all three components, not by applying the standard KEMS pressure calibration procedure, but from the measured ion intensity ratios of Cu+ to Sn+ using a recently published mathematical regression technique. The intermediate data obtained directly from the regression technique are the Redlich-Kister ternary L-parameters that are, as a function of temperature, as follows: L0 D (-59473 +/- 7057) + (726.8 +/- 42.3)[middle dot]T - (89.0 +/- 5.1)[middle dot]T[middle dot]ln(T); L1 = (156840 +/- 5.2E - 9) - (80 +/- 3.3E - 11)[middle dot]T - (5.57E - 11 +/- 4E - 12)[middle dot]T[middle dot]ln(T); L2 = (-137168 +/- 8819) + (592.4 +/- 52.9)[middle dot]T - (70.6 +/- 6.4)[middle dot]T[middle dot]ln(T). By using these values together with binary parameters taken from the literature, we were able to calculate several other thermodynamic functions of mixing. In particular, the partial heat of mixing of indium and its activity, which we evaluated and compared with the measured values along the Cu/Sn = 1 isopleths. We obtained a good agreement between the calculated and measured values for partial heats while in the case of activity a good agreement between the two data sets is limited to a lower mole fraction of indium.

Popovic, A.; Bencze, L.

2006-11-01

244

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.

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

2014-01-01

245

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

SciTech Connect

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

Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A. [Department of Electrical Engineering, University of Bologna, Viale Risorgimento 2, 40136 Bologna (Italy)

2012-08-01

246

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

247

Lipophilicity indices derived from the liquid chromatographic behavior observed under bimodal retention conditions (reversed phase/hydrophilic interaction): application to a representative set of pyridinium oximes.  

PubMed

The liquid chromatographic behavior observed under bimodal retention conditions (reversed phase and hydrophilic interaction) offers a new basis for the determination of some derived lipophilicity indices. The experiments were carried out on a representative group (30 compounds) of pyridinium oximes, therapeutically tested in acetylcholinesterase reactivation, covering a large range of lipophilic character. The chromatographic behavior was observed on a mixed mode acting stationary phase, resulting from covalent functionalization of high purity spherical silica with long chain alkyl groups terminated by a polar environment created through the vicinal diol substitution at the lasting carbon atoms (Acclaim Mixed Mode HILIC 1 column). Elution was achieved by combining different proportions of 5 mM ammonium formiate solutions in water and acetonitrile. The derived lipophilicity indices were compared with logP values resulting from different computational algorithms. The correlations between experimental and computed data sets are significant. To obtain a better insight on the transition from reversed phase to hydrophilic interaction retention mechanisms, the variation of the thermodynamic parameters determined through the van?t Hoff approach was also discussed. PMID:24720980

Voicu, Victor; Sârbu, Costel; Tache, Florentin; Mic?le, Florina; R?dulescu, ?tefan Flavian; Sakurada, Koichi; Ohta, Hikoto; Medvedovici, Andrei

2014-05-01

248

Disentangling fluxes of energy and matter in plasma-surface interactions: Effect of process parameters  

SciTech Connect

The possibility to discriminate between the relative importance of the fluxes of energy and matter in plasma-surface interaction is demonstrated by the energy flux measurements in low-temperature plasmas ignited by the radio frequency discharge (power and pressure ranges 50-250 W and 8-11.5 Pa) in Ar, Ar+H{sub 2}, and Ar+H{sub 2}+CH{sub 4} gas mixtures typically used in nanoscale synthesis and processing of silicon- and carbon-based nanostructures. It is shown that by varying the gas composition and pressure, the discharge power, and the surface bias one can effectively control the surface temperature and the matter supply rates. The experimental findings are explained in terms of the plasma-specific reactions in the plasma bulk and on the surface.

Wolter, M. [Institute of Experimental and Applied Physics, University of Kiel, D-24098 Kiel (Germany); Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Levchenko, I.; Ostrikov, K. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia); Kersten, H. [Institute of Experimental and Applied Physics, University of Kiel, D-24098 Kiel (Germany); Kumar, S. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Nanotechnology and Integrated BioEngineering Centre, University of Ulster at Jordanstown, Newtownabbey, Northern Ireland BT37 0QB (United Kingdom)

2010-09-15

249

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

PubMed

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

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

2014-05-01

250

Two Interaction Modes of the gp41Derived Peptides with gp41 and Their Correlation with Antimembrane Fusion Activity  

Microsoft Academic Search

Peptides derived from gp41 effectively block the gp41-mediated cell fusion or HIV infection. A 36-mer (naDP178), 51-mer (C51) and 27-mer peptide (C27) from the membrane proximal region of gp41 have been examined their interaction modes with the coiled-coil motif of gp41 presented in thioredoxin (Trx-N) or the bacterially expressed ectodomain of gp41 (Ec-gp41ec). All of these peptides effectively inhibited the

Jae-Ryeon Ryu; Bong-Suk Jin; Moo-Jin Suh; Young-Sook Yoo; Seung Hee Yoon; Eun-Rhan Woo; Yeon Gyu Yu

1999-01-01

251

Determination of the Jones matrix of an LC cell and derivation of the physical parameters of the LC molecules  

NASA Astrophysics Data System (ADS)

The wavelength-dependent Jones matrix representation of a twisted-nematic liquid crystal (TN-LC) cell contains four independent parameters. The absolute values of these parameters and two mutual sign relationships can be determined from comparatively simple transmission measurements of the TN-LC cells sandwiched between two rotatable polarizers. The physical parameters of the cell (twist angle ?, director orientation ?, birefringence ?) can be retrieved if the Jones matrix is known for more than one wavelength. We have measured the Jones matrices of the TN-LC cells of a translucent Sony LCX-016 microdisplay for six wavelengths ranging from 488nm to 1064nm and determined the physical parameters of the cell. We have also measured the Jones matrices for one wavelength for a number of applied voltages. These experimental results show that it is not sufficiently exact to calculate the Jones matrix from the known physical parameters of the cell assuming a voltage-dependent birefringence only. We attribute the deviations from the theoretical model to edge effects which are not taken into account. The direct experimental determination of the Jones matrix components is therefore preferable and permits a more accurate simulation of the TN-LC microdisplay in experimental configurations involving other polarization-dependent optical components.

Hermerschmidt, Andreas; Quiram, Stephanie; Kallmeyer, Frank; Eichler, Hans Joachim

2007-05-01

252

Pharmacokinetic Drug Interactions of Morphine, Codeine, and Their Derivatives: Theory and Clinical Reality, Part I  

Microsoft Academic Search

Pharmacokinetic drug-drug interactions with morphine, hydromorphone, and oxymorphone are reviewed in this column. Morphine is a naturally occurring opiate that is metabolized chiefly through glucuronidation by uridine diphosphate glucuronosyl transferase (UGT) enzymes in the liver. These enzymes produce an active analgesic metabolite and a potentially toxic metabolite. In vivo drug-drug interaction studies with morphine are few, but they do suggest

SCOTT C. ARMSTRONG; KELLY L. COZZA

2003-01-01

253

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

Microsoft Academic Search

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

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

2012-01-01

254

Neutral Winds Derived from Iri Parameters and from the HWM87 Wind Model for the Sundial Campaign of September, 1986.  

National Technical Information Service (NTIS)

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....

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

1990-01-01

255

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

PubMed Central

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

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

2013-01-01

256

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

257

Gas Chromatographic Derivation of the Solubility Parameters of Polychbrinated Biphenyls with the Inclusion of Cis-Trans and Optical Isomerism and Orientational Disorder  

Microsoft Academic Search

A thermodynamic model (SOFA) was used to derive molar (subcooled) liquid volume, heat of vaporization and Scatchard-Hildebrand solubility parameters of polychlorinated biphenyls. Differences in molar volume and heat of vaporization between cis-trans isomers and between enantiomers were accounted for by specific fragment contributions and by an increase or decrease of molar volume and heat of vaporization when mixed cis-trans isomers

H. A. J. Govers; P. De Voogt

1995-01-01

258

Allometric modeling of ciclesonide, a nonhalogenated glucocorticoid, and its active metabolite, desisobutyrylciclesonide, using animal-derived pharmacokinetic parameters.  

PubMed

Ciclesonide, a novel glucocorticosteroid, through a rapid metabolism to desisobutyryl-ciclesonide (des-ciclesonide), provides an effective treatment option for asthma episodes by the inhaled route of administration. The availability of pharmacokinetic parameters (clearance [CL/F]; volume of distribution [Vd/F]; elimination half-life [T(½)]; and elimination rate constant [Kel]) in mice, rats, rabbits, and dogs enabled the prediction of human parameter values for des-ciclesonide using the well-accepted tool of allometry after intravenous administration of ciclesonide. However, as a result of the rapid conversion of ciclesonide, it was possible to perform allometry for the CL parameter only. Simple allometry (CL = 4.781W?·????; R² = 0.9968) appeared to predict the CL of ciclesonide in close proximity of the observed value (observed: 101.25 L/h versus predicted: 135.62 L/h). In a similar manner, simple allometry predicted the human pharmacokinetic parameters of des-ciclesonide (CL/F, Vd/F, T(½), and Kel) within a two- to threefold range of the observed values. The allometric equations for des-ciclesonide parameter values were: CL/F = 4.8166W?·??² (R² = 0.8598); Vd/F = 19.052W?·?³² (R² = 0.9049); T(½) = 3.7598W??·¹?¹¹(R² = 0.8551); and Kel = 0.1832W?·¹??? (R² = 0.8632). In conclusion, the data suggested that allometry tool may be amenable for the prediction of the pharmacokinetic parameters of des-ciclesonide despite differences in the conversion rates and bioavailability of the active metabolite in various animal species. PMID:19417590

Srinivas, Nuggehally R; Ahlawat, Preeti; Shaik, Jafar Bhasha

2013-01-01

259

Closed string Ramond-Ramond proposed higher derivative interactions on fermionic amplitudes in IIB  

NASA Astrophysics Data System (ADS)

The complete form of the amplitude of one closed string Ramond-Ramond (RR), two fermionic strings and one scalar field in IIB superstring theory has been computed in detail. Deriving by using suitable gauge fixing, we discover some new vertices and their higher derivative corrections. We investigate both infinite gauge and scalar u-channel poles of this amplitude. In particular, by using the fact that the kinetic term of fermion fields has no correction, employing Born-Infeld action, the Wess-Zumino terms and their higher derivative corrections, we discover all infinite t,s-channel fermion poles. The couplings between one RR and two fermions and all their infinite higher derivative corrections have been explored. In order to look for all infinite (s+t+u)-channel scalar/gauge poles for p+2=n, p=n cases, we obtain the couplings between two fermions-two scalars and two fermions, one scalar and one gauge field as well as all their infinite higher derivative corrections in type IIB. Specifically we make various comments based on arXiv:1205.5079 in favor of universality conjecture for all order higher derivative corrections (with or without low energy expansion) and the relation of open/closed string that is responsible for all superstring scattering amplitudes in IIA, IIB.

Hatefi, Ehsan

2014-03-01

260

Kinetic and spectral parameters of interaction of Citrobacter freundii methionine ?-lyase with amino acids.  

PubMed

Kinetic parameters of Citrobacter freundii methionine ?-lyase were determined with substrates in ?-elimination reactions as well as the inhibition of the enzyme in the ?-elimination of L-methionine by amino acids with different structure. The data indicate an important contribution of the sulfur atom and methylene groups to the efficiency of binding of substrates and inhibitors. The rate constants of the enzyme-catalyzed exchange of C-?- and C-?-protons with deuterium were determined, as well as the kinetic isotope effect of the deuterium label in the C-?-position of inhibitors on the rate of exchange of their ?-protons. Neither stereoselectivity in the ?-proton exchange nor noticeable ?-isotope effect on the exchange rates of ?-protons was found. The ionic and tautomeric composition of the external Schiff base of methionine ?-lyase was determined. Spectral characteristics (absorption and circular dichroism spectra) of complexes with substrates and inhibitors were determined. The spectral and kinetic data indicate that deamination of aminocrotonate should be the rate-determining stage of the enzymatic reaction. PMID:21166645

Morozova, E A; Bazhulina, N P; Anufrieva, N V; Mamaeva, D V; Tkachev, Y V; Streltsov, S A; Timofeev, V P; Faleev, N G; Demidkina, T V

2010-10-01

261

Biomolecule and Surface Interactions Investigated Using a Multi-Parameter QCM technique  

NASA Astrophysics Data System (ADS)

Biomolecules in contact with solid surfaces is a situation of broad scientific and technological interest, and there is a need for new tools to study these interactions. For instance, due to the influence from the surface adsorbed biomolecules might adopt a conformation, and hence function, that differs from that of the native state. We have developed a surface-based sensor based on the quartz crystal micro balance (QCM) technique, where both the resonant frequency and the energy dissipation are measured simultaneously for a non-driven (freely oscillating) sensor crystal. This offers a possibility to make real time measurements of changes in the viscoelastic properties, directly related to conformational changes, during biomolecule adsorption. Examples of how this type of measurements contributes with such information are presented using examples of: (i) hemoglobin adsorbtion (ii) antigen-antibody recognition (iii) lipid vesicle (liposome) adsorption and fusion into a supported bilayer and (iv) antibody recognition of proteins incorporated in supported membranes. We also demonstrate the possibility to theoretically treat the QCM response, and how changes in the complex shear modulus can be estimated.

Höök, Fredrik; Glasmästar, Karin; Persson, Annette; Reimhult, Erik; Kasemo, Bengt

2000-03-01

262

Complexes between linoleate and native or aggregated ?-lactoglobulin: interaction parameters and in vitro cytotoxic effect.  

PubMed

The dairy protein ?-lactoglobulin (?lg) is known to form a complex with fatty acids (FA). Due to industrial processing, ?lg is often in its non-native form in food products, which can modify the FA/?lg complex properties. We investigated the interaction of bovine ?lg, in selected structural forms (native ?lg, a covalent dimer and as nanoparticles), with linoleate (C18:2). Using fluorescence and Isothermal Titration Calorimetry, linoleate was found to bind ?lg at two different binding sites. Regardless of the structural state of ?lg, association constants remained in the same order of magnitude. However, the stoichiometry increased up to 6-fold for nanoparticles, compared to that of native ?lg. The impact of these structural changes on linoleate uptake in vitro was measured by cytotoxicity assays on Caco-2 cells. The order of cytotoxicity of linoleate was as follows: free>complexed to dimers>complexed to nanoparticles>complexed to native ?lg. Therefore, the in vitro cytotoxicity of linoleate could be modulated by altering the state of ?lg aggregation, which in turn affects its binding capacity to the FA. PMID:23870962

Le Maux, Solène; Bouhallab, Saïd; Giblin, Linda; Brodkorb, André; Croguennec, Thomas

2013-12-01

263

Interacting holographic dark energy with variable deceleration parameter and accreting black holes in Bianchi type-V universe  

NASA Astrophysics Data System (ADS)

In this paper, we have considered the spatially homogeneous and anisotropic Bianchi type-V space time filled with two interacting fluids; dark matter and a hypothetical isotropic fluid as the holographic dark energy components. To obtain an exact solution of the Einstein's field equations, we used the assumption of time dependent deceleration parameter. We have investigated geometric and kinematic properties of the model. It is observed that the anisotropy parameter of the universe approaches to zero and the universe achieve flatness for large cosmic time. We have shown that this expanding solution is stable against the perturbation with respect to anisotropic spatial directions. We have also studied the evolution of the mass of a black hole embedded in a universe which interacts with a combination of dark matter and dark energy, considering that in the vicinity of the black hole the metric is of Schwarzschild type. We found that the black hole mass increases with the evolution of the universe, and on later epochs the increase in mass stops as dark energy accretion takes over. The results are found to be consistent with recent cosmological observations.

Sarkar, Sanjay

2014-07-01

264

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

PubMed

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

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

2013-03-01

265

A functional analysis of PCNA-binding peptides derived from protein sequence, interaction screening and rational design  

PubMed Central

PCNA has no intrinsic enzymatic function, but functions as a sliding platform to mediate protein interactions with the DNA strand. Many proteins interact with PCNA through a small conserved motif with consensus QxxLxxFF. This work uses S. pombe and human cells to analyse the function of PCNA-binding peptides. Interacting peptides were identified using two-hybrid screening; one (pep102) binds directly to a physiologically relevant site on PCNA. The EGFP-pep102 over-expression phenotype is consistent with competitive blocking of PCNA-protein interactions. Various PCNA-binding peptides were all shown to inhibit PCNA function by competitive binding in both human and S. pombe cells as EGFP fusion proteins. The action of a p21(WAF1/Cip1)-derived peptide was complicated by the presence of additional functional domains and possible post-translational modification. The activity of pep102 was hampered by low expression in both model systems. The peptide derived from rational design (con1) was stable, highly active in inhibiting PCNA function both S. pombe and human cells and showed a high affinity for PCNA both in vitro and in vivo. These results validate the use of functional screening in yeast to identify peptide aptamers that are functional in mammalian cells; such aptamers provide excellent leads for small molecule anti-proliferative therapies.

Warbrick, Emma

2009-01-01

266

Land cover conversion and degradation analyses through coupled soil-plant biophysical parameters derived from hyperspectral EO1 Hyperion  

Microsoft Academic Search

Land degradation in semiarid areas results from various factors, including climate variations and human activity, and can lead to desertification. The process of degradation results in simultaneous and complex variations of many interrelated soil and vegetation biophysical parameters, rendering it difficult to develop simple and robust remote sensing mapping and monitoring approaches. In this study, we tested the use of

Alfredo R. Huete; Tomoaki Miura; Xiang Gao

2003-01-01

267

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

268

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

269

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

270

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

271

Ionic composition of seawaters and derived saline solutions determined by ion chromatography and its relation to other water quality parameters.  

PubMed

Ion chromatography (IC) presents new possibilities for assessing information about environmental samples, namely waters of various compositions, ranging from high-purity water to highly saline ones. Constant proportion between major ions present in seawater, has been assumed in the past, from which the first practical equation relating chlorinity and salinity has been developed, being later substituted by a practical salinity scale, derived from conductivity measurements relative to a standard seawater, according to internationally accepted recommended procedures. Seawaters are characterized by salinity values around 35 while derived saline solutions may present considerable changes in ionic composition, conductivity, hence on salinity. Natural and anthropogenic phenomena may introduce new issues requiring clarification for which qualitative and quantitative information from additional sources is useful, e.g. ionic composition from IC. The different ranges of concentration of major and minor species present in seawater and derived saline solutions are a challenge for the optimization of a practical methodology for composition assessment in two single IC runs, one for anions and another one for cations, which has been attained in this work. Composition of saline solutions determined by IC was critically assessed in terms of anion-cation balance and further related to conductivity and salinity measurements aiming to evaluate the quality/completeness of ion chromatographic analyses performed at preselected conditions and to search for other meaningful relations for efficient recognition/distinction between saline solutions of different types. PMID:18829032

Gros, Natasa; Camões, M F; Oliveira, Cristina; Silva, M C R

2008-11-01

272

Specific Recognition of p53 Tetramers by Peptides Derived from p53 Interacting Proteins  

Microsoft Academic Search

Oligomerization plays a major role in regulating the activity of many proteins, and in modulating their interactions. p53 is a homotetrameric transcription factor that has a pivotal role in tumor suppression. Its tetramerization domain is contained within its C-terminal domain, which is a site for numerous protein-protein interactions. Those can either depend on or regulate p53 oligomerization. Here we screened

Ronen Gabizon; Tobias Brandt; Shahar Sukenik; Noa Lahav; Mario Lebendiker; Deborah E. Shalev; Dmitry Veprintsev; Assaf Friedler

2012-01-01

273

A sensitivity analysis of the parameters controlling water-sediment interactions in the coastal zone: Consequences to man and environment  

NASA Astrophysics Data System (ADS)

A sensitivity analysis has been carried out on the basis of the local and global sensitivity indexes for selected radionuclides ( 3H, 137Cs, 238Pu, 241Am and 244Cm) and main parameters describing the water-sediment interaction (sediment reworking rate, pore-water turnover rate, sediment distribution coefficient, suspended sediment load in water column, sedimentation rate, molecular diffusion coefficient, surface sediment thickness, porosity of bottom sediment and density of sediment material). Sensitivity analysis has been carried out using a compartment model for dose assessment to man and biota, which includes the processes of advection of radioactivity between compartments, sedimentation, diffusion of radioactivity through pore water in sediments, particle mixing, pore water mixing and a burial process of radioactivity in deep sediment layers. The sensitivity analysis indicates that for the conditions in the Norwegian Current (the Norwegian Sea) particle mixing dominates the transfer of radioactivity between the bottom water and surface sediment compartments. For the conditions in the Ob Bay (the Kara Sea), the sedimentation process has also been found to be significant. The calculated dynamics of the sensitivity indexes demonstrate clearly the complexities encountered when modeling water-sediment interactions. It is also shown that the results can be strongly dependent on the time of analysis. For example, given a specific change of parameters the radionuclide concentration will be either increased or decreased, depending on the temporal interval. Information provided by the sensitivity analysis can contribute to a better understanding of experimental data and might further improve the parameterization process. The obtained results show that water-sediment interactions can play a key role in the marine coastal environment, thus demonstrating the need to further deepen our understanding of them, as well as improve the models describing them.

Iosjpe, M.

2011-10-01

274

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

PubMed

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

Uesawa, Yoshihiro; Mohri, Kiminori

2008-01-01

275

Analytic derivative couplings between configuration-interaction-singles states with built-in electron-translation factors for translational invariance.  

PubMed

We present a method for analytically calculating the derivative couplings between a pair of configuration-interaction-singles (CIS) excited states obtained in an atom-centered basis. Our theory is exact and has been derived using two completely independent approaches: one inspired by the Hellmann-Feynman theorem and the other following from direct differentiation. (The former is new, while the latter is in the spirit of existing approaches in the literature.) Our expression for the derivative couplings incorporates all Pulay effects associated with the use of an atom-centered basis, and the computational cost is minimal, roughly comparable to that of a single CIS energy gradient. We have validated our method against CIS finite-difference results and have applied it to the lowest lying excited states of naphthalene; we find that naphthalene derivative couplings include Pulay contributions sufficient to have a qualitative effect. Going beyond standard problems in analytic gradient theory, we have also constructed a correction, based on perturbative electron-translation factors, for including electronic momentum and eliminating spurious components of the derivative couplings that break translational symmetry. This correction is general and can be applied to any level of electronic structure theory. PMID:22191862

Fatehi, Shervin; Alguire, Ethan; Shao, Yihan; Subotnik, Joseph E

2011-12-21

276

Supramolecular interactions in the structures of carboxylate derivatives of cymantrene and single-charged cations  

NASA Astrophysics Data System (ADS)

The ability of cymantrenecarboxylate derivatives to form supramolecular structures has been studied for ten newly prepared derivatives of cymantrenecarboxylic acid (?5-C5H4COOH)Mn(CO)3 and two new derivatives of ?-cymantrenoylpropionic acid (?5-C5H4CO(CH2)2COOH)Mn(CO)3 with cations of alkaline metals and protonated polytopic nitrogen bases of various geometries. It has been shown that structures of this kind (two- and three-dimensional) are formed owing to specific properties of the cymantrene moiety, i.e., its ability to coordinate metal ions via CO groups (to form isocarbonyl bridges) and to form CO⋯H hydrogen bonds, but in most of the cases the type of the structure is determined by the cation. In case of Li cymantrenecarboxylate complex the formation of hexameric molecules having a cavity was found. The crystal and molecular structure of cymantrenecarboxylic acid has been described for the first time.

Ilyukhin, Andrey B.; Koroteev, Pavel S.; Kiskin, Mikhail A.; Dobrokhotova, Zhanna V.; Novotortsev, Vladimir M.

2013-02-01

277

A generalized formulation of ion-? electron interactions: role of the nonelectrostatic component and probe of the potential parameter transferability.  

PubMed

The intermolecular potentials for hexafluorobenzene (HFBz) and 1,3,5-trifluorobenzene (TFBz) interacting with alkali (M(+); M = Li, Na, K, Rb, Cs) and halogen (X(-); X = F, Cl, Br, I) ions are provided as a combination of electrostatic and nonelectrostatic terms. The ion-HFBz and ion-TFBz electrostatic components are formulated as a sum of Coulombic potentials associated with the interactions between the ion charge and point charges on the molecular frame, whose distributions are consistent with the permanent quadrupole moment of HFBz and TFBz, respectively. The corresponding nonelectrostatic components are represented as a sum of effective potential functions, each one having a specific physical meaning, related to ion-molecular bond pair interactions. In the present paper, we test the transferability of the ion-bond potential parameters. Moreover, the powerfulness of the model is analyzed by comparing predicted binding energies and equilibrium geometries for the family of M(+)-HFBz, X(-)-HFBz, M(+)-TFBz, and X(-)-TFBz systems with available ab initio results. PMID:20945865

Albertí, M; Aguilar, A; Lucas, J M; Pirani, F

2010-11-11

278

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

279

Effects of Forest on the Snow Parameters Derived from Microwave Measurements during the Boreas Winter Field Campaign  

NASA Astrophysics Data System (ADS)

Passive microwave data have been used to infer the areal snow water equivalent (SWE) with some success. However, the accuracy of these retrieved SWE values have not been well determined for heterogeneous vegetated regions. The Boreal Ecosystem-Atmosphere Study (BOREAS) Winter Field Campaign (WFC), which took place in February 1994, provided the opportunity to study in detail the effects of boreal forests on snow parameter retrievals. Preliminary results reconfirmed the relationship between microwave brightness temperature and snow water equivalent. The pronounced effect of forest cover on SWE retrieval was studied. A modified vegetation mixing algorithm is proposed to account for the forest cover. The relationship between the microwave signature and observed snowpack parameters matches results from this model.

Chang, A. T. C.; Foster, J. L.; Hall, D. K.

1996-12-01

280

Optical and dielectric parameters of KAl(SO 4) 2·12H 20 derived from IR reflection measurements  

NASA Astrophysics Data System (ADS)

The near normal incidence IR reflection spectra for KAl(S0 4) 2· 12H 20 have been recorded at 270, 150 and 77 K in the range 30-4000 cm -1. The optical constants, n and k, dielectric parameters, ?' and ??, LO and TO mode frequencies, conductivity ?, and resistivity ? and absorption coefficient have been calculated from these spectra by employing the Kramers-Kronig dispersion relations.

Malekfar, R.; Sherman, W. F.

1991-07-01

281

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

Microsoft Academic Search

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

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

1997-01-01

282

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

Microsoft Academic Search

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

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

1997-01-01

283

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

SciTech Connect

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

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

2010-05-28

284

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

285

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

286

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

287

Global variations in gravity-derived oceanic crustal thickness: Implications on oceanic crustal accretion and hotspot-lithosphere interactions  

NASA Astrophysics Data System (ADS)

We present a new global model of oceanic crustal thickness based on inversion of global oceanic gravity anomaly with constrains from seismic crustal thickness profiles. We first removed from the observed marine free-air gravity anomaly all gravitational effects that can be estimated and removed using independent constraints, including the effects of seafloor topography, marine sediment thickness, and the age-dependent thermal structure of the oceanic lithosphere. We then calculated models of gravity-derived crustal thickness through inversion of the residual mantle Bouguer anomaly using best-fitting gravity-modeling parameters obtained from comparison with seismically determined crustal thickness profiles. Modeling results show that about 5% of the global crustal volume (or 9% of the global oceanic surface area) is associated with model crustal thickness <5.2 km (designated as "thin" crust), while 56% of the crustal volume (or 65% of the surface area) is associated with crustal thickness of 5.2-8.6 km thick (designated as "normal" crust). The remaining 39% of the crustal volume (or 26% of the surface area) is associated with crustal thickness >8.6 km and is interpreted to have been affected by excess magmatism. The percentage of oceanic crustal volume that is associated with thick crustal thickness (>8.6 km) varies greatly among tectonic plates: Pacific (33%), Africa (50%), Antarctic (33%), Australia (30%), South America (34%), Nazca (23%), North America (47%), India (74%), Eurasia (68%), Cocos (20%), Philippine (26%), Scotia (41%), Caribbean (89%), Arabian (82%), and Juan de Fuca (21%). We also found that distribution of thickened oceanic crust (>8.6 km) seems to depend on spreading rate and lithospheric age: (1) On ocean basins younger than 5 Ma, regions of thickened crust are predominantly associated with slow and ultraslow spreading ridges. The relatively strong lithospheric plate at slow and ultraslow ridges might facilitate the loading of large magmatic emplacements on the plate. (2) In contrast, crustal thickness near fast and intermediately fast spreading ridges typically does not exceed 7-8 km. The relatively weak lithosphere at fast and intermediately fast ridges might make it harder for excess magmatism to accrete. We further speculate that the relatively wide partial melting zones in the upper mantle beneath the fast and intermediately fast ridges might act as "buffer" zones, thus diluting the melt anomalies from the underlying hotspots or regions of mantle heterogeneities. (3) As the crustal age increases and the lithospheric plate thickens, regions of thickened crust start to develop on ocean basins that were originally created at fast and intermediately fast ridges. The integrated crustal volume for fast and intermediately fast ocean crust appears to reach peak values for certain geological periods, such as 40-50 Ma and 70-80 Ma. The newly constructed global models of gravity-derived crustal thickness, combining with geochemical and other constraints, can be used to investigate the processes of oceanic crustal accretion and hotspot-lithosphere interactions.

Lin, J.; Zhu, J.

2012-12-01

288

Experimental and theoretical NMR studies of interaction between phenylalanine derivative and egg yolk lecithin.  

PubMed

The interaction of phenylalanine diamide (Ac-Phe-NHMe) with egg yolk lecithin (EYL) in chloroform was studied by (1) H and (13) C NMR. Six complexes EYL-Ac-Phe-NHMe, stabilized by N-H···O or/and C-H···O hydrogen bonds, were optimized at M06-2X/6-31G(d,p) level. The assignment of EYL and Ac-Phe-NHMe NMR signals was supported using GIAO (gauge including atomic orbital) NMR calculations at VSXC and B3LYP level of theory combined with STO-3Gmag basis set. Results of our study indicate that the interaction of peptides with lecithin occurs mainly in the polar 'head' of the lecithin. Additionally, the most probable lecithin site of H-bond interaction with Ac-Phe-NHMe is the negatively charged oxygen in phosphate group that acts as proton acceptor. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24639342

Wa??sa, Roksana; Ptak, Tomasz; Siod?ak, Dawid; Kupka, Teobald; Broda, Ma?gorzata A

2014-06-01

289

Interaction of some thiouracil derivatives with horseradish peroxidase by difference spectroscopy  

NASA Astrophysics Data System (ADS)

Interactions of horseradish peroxidase with propylthiouracil, thiouracil and benzylthiouracil change its absorption spectrum due to perturbation in the region of the heme group of the protein on drug-binding. In the case of propylthiouracil, the interaction might take place near the tryptophan group. In this report, binding of the uracils to the peroxidase was characterized by difference spectroscopy. Propylthiouracil and thiouracil were the most strongly bound of these uracil drugs. The presence of the thiol group in the uracil molecule together with a suitable molecular size seem to be involved in relative strong binding between the enzyme and these compounds.

de Aspuru, Eduardo Ochoa; Lourdes Zatón, Ana M.

1997-07-01

290

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

291

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

NASA Astrophysics Data System (ADS)

A 167-parameter, 3-D shape model of the Earth-crossing asteroid Castalia, obtained from inversion of delay-Doppler images (Hudson and Ostro, 1994, Science263,940-943) constrained the object's pole to lie on a cone of half angle 55 ± 10° centered on the radar line of sight (right ascension 0.3 hr, declination 25.4°) at the time of observations (Aug. 22, 1989) but could not constrain the pole's azimuthal orientation or the sense of rotation. Here we fit lightcurves obtained at Table Mountain Observatory on Aug. 23-25 with lightcurves calculated from Castalia's shape and Hapke's photometric model (Hapke 1981, J. Geophys. Res.86,3039-3054; 1984, Icarus59,41-59; 1986, Icarus67,264-280). The fits strongly constrain Castalia's spin state to one of two possibilities. One has a north pole within ˜13° of ? = 253°, ? = 56° and a sidereal spin period P= 4.089 ± 0.001 hr. The other has a south pole within ˜13° of ? = 242°, ? = 7° and a sidereal spin period P= 4.094 ± 0.001 hr. The north-pole solution has global-average Hapke photometric parameters w= 0.38 ± 0.07, g= -0.11 ± 0.09, ? = 46° ± 10° while the south-pole solution has w= 0.24 ± 0.07, g= -0.30 ± 0.09, ? = 25° ± 10°. Due to the large solar phase angles (60°-90°) the fits are not sensitive to the opposition surge parameters hand B0. At a more subtle level, the least-bifurcated shape ("lower-bound model") allowed by the radar data (Hudson and Ostro, 1994, Science263,940-943) consistently gives statistically better fits than the more bifurcated possibilities. However, the differences are small enough that the possibility that they are due to unmodeled photometric effects cannot be discounted. The fits are improved by allowing the macroscopic roughness parameter ? to be a function of surface position. Statistically, this process improves the north-pole solution more than the south-pole solution suggesting that the radar observations viewed a northern latitude, thereby indicating a resolution of the "mirror ambiguity" inherent in the single-date radar data set.

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

1997-11-01

292

Nucleon-nucleon interaction as derived from the De Rújula, Georgi, Glashow phenomenological quark-quark potential  

NASA Astrophysics Data System (ADS)

The nucleon-nucleon interaction, originating from the phenomenological quark-quark interaction: one gluon exchange with an ad hoc confining potential, is rigorously derived. The coupling constants of this potential and the quark masses-which determine the strengths of the NN potentials in the various channels-had been previously reliably determined from the masses of the s-wave baryons. Two distinguishing features of this study are the reliable nature of the coupling constants and quark masses used and the inclusion of the detailed radial dynamics of quarks. The main results are as follows: (i) exchange of colored quarks among other things leads to short-range strongly repulsive central NN potentials in the odd channels alone, i.e., it yields the saturation property of nuclear forces; (ii) the spin-orbit (tensor) potential between quarks goes over to the spin-orbit (tensor) potential between nucleons; (iii) both these spin-orbit and tensor potentials between nucleons are found to have the correct signatures but they are very weak; (iv) there is insufficient attraction in the NN potentials in the intermediate range, so that the colored quark-exchange mechanism is not adequate to keep the deuteron bound. The NN potentials derived from one gluon exchange with an ad hoc confining potential are compared finally with the corresponding phenomenological ones. NUCLEAR STRUCTURE NN interaction from nonrelativistic quantum chromodynamics. Quark exchange, spin-orbit and tensor potentials, short-range repulsive core.

Warke, C. S.; Shanker, R.

1980-06-01

293

Correlation among electronic polarizability, optical basicity and interaction parameter of Bi 2O 3-B 2O 3 glasses  

NASA Astrophysics Data System (ADS)

For optical basicity and electronic polarizability, the previous studies basically concentrate on the wavelength range of the visible light region. However, heavy metal oxides glasses have a reputation of being good materials for infrared region. In this study, new data of the average electronic polarizability of the oxide ion ?, optical basicity ? and Yamashita-Kurosawa's interaction parameter A of Bi 2O 3-B 2O 3 glasses have been calculated in a wavelength range from 404.66 to 1083.03 nm. The present investigation suggests that both ? and ? increase gradually with increasing wave number, and A decreases with increasing wave number. Furthermore, close correlations are studied among ?, ?, A and refractive index n in this paper. Particularly, it has been found that a quantitative relationship between electronic polarizability and optical basicity is observed in a wavelength range from 404.66 to 1083.03 nm. Our present study extends over a wide range of ?, ? and A values.

Zhao, Xinyu; Wang, Xiaoli; Lin, Hai; Wang, Zhiqiang

2007-03-01

294

Derivation of Structure Parameters of Temperature and Humidity in the Convective Boundary Layer from Large-Eddy Simulations and Implications for the Interpretation of Scintillometer Observations  

NASA Astrophysics Data System (ADS)

We derive the turbulent structure parameters of temperature CT^2 and humidity C_q^2 from high-resolution large-eddy simulations (LES) of a homogeneously-heated convective boundary layer. Boundary conditions and model forcing were derived from measurements at Cabauw in The Netherlands. Three different methods to obtain the structure-parameters from LES are investigated. The shape of the vertical structure-parameter profiles from all three methods compare well with former experimental and LES results. Depending on the method, deviations in the magnitude up to a factor of two are found and traced back to the effects of discretization and numerical dissipation of the advection scheme. Furthermore, we validate the LES data with airborne and large-aperture scintillometer (LAS) measurements at Cabauw. Virtual path measurements are used to study the variability of CT^2 in the mixed layer and surface layer and its implications for airborne and LAS measurements. A high variability of CT^2 along a given horizontal path in the LES data is associated with plumes (high values) and downdrafts (low values). The path average of CT^2 varies rapidly in time due to the limited path length. The LES results suggest that measured path averages require sufficient temporal averaging and an adequate ratio of path length to height above the ground for the LAS in order to approach the domain average of CT^2.

Maronga, Björn; Moene, Arnold F.; van Dinther, Daniëlle; Raasch, Siegfried; Bosveld, Fred C.; Gioli, Beniamino

2013-07-01

295

Multiplicity distributions in hadron interactions derived from the statistical bootstrap model  

Microsoft Academic Search

We give a self-contained (though sketchy) derivation of the charged multiplicity distribution of final hadrons in a simplified (only pions) version of the statistical bootstrap model (SBM). The analytical form of this distribution is determined by two prominent features of SBM: a singularity at some temperatureT0 (related to the phase transition hadrons ? quark-gluon plasma) and the production of Poisson-distributed

G. J. H. Burgers; C. Fuglesang; R. Hagedorn; V. Kuvshinov

1990-01-01

296

Evaluation of intensity and energy interaction parameters for the complexation of Pr(III) with selected nucleoside and nucleotide through absorption spectral studies  

NASA Astrophysics Data System (ADS)

The interactions of Pr(III) with nucleosides and nucleotides have been studied in different organic solvents employing absorption difference and comparative absorption spectrophotometry. The magnitudes of the variations in both energy and intensity interaction parameters were used to explore the degree of outer and inner sphere co-ordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Various electronic spectral parameters like Slater-Condon (Fk), Racah (Ek), Lande parameter (?4f), Nephelauxatic ratio (?), bonding (b1/2), percentage covalency (?) and intensity parameters like oscillator strength (P) and Judd Ofelt electronic dipole intensity parameter (T?, ? = 2, 4, 6) have been evaluated. The variation of these evaluated parameters were employed to interpret the nature of binding of Pr(III) with different ligands i.e. Adenosine/ATP in presence and absence of Ca2+.

Bendangsenla, N.; Moaienla, T.; David Singh, Th.; Sumitra, Ch.; Rajmuhon Singh, N.; Indira Devi, M.

2013-02-01

297

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

SciTech Connect

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

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

2012-11-15

298

Diffraction effects in the parametric interaction of acoustic waves: application to measurements of the nonlinearity parameter B\\/A in liquids  

Microsoft Academic Search

This paper deals with diffraction effects related to the determination of nonlinearity parameters B\\/A in liquids using the parametric interaction. A diffraction model, based on plane wave expansions, is applied to weak nonlinear interactions between two ultrasonic waves propagating in an absorbing medium. A validation of the model has been carried out with an experiment performed using an optical interferometer.

C. Barriere; D. Royer

2001-01-01

299

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

PubMed Central

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

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

2013-01-01

300

Deriving Parameters of Topographic Diffusion and Incision Models by Simulating Space-Time Equivalent Valley Evolution with LiDAR DTM  

NASA Astrophysics Data System (ADS)

Generally, the changes of landscapes are caused by interactions among many surface processes in a long time. According to previous studies in decades, some of the surface processes such as sediment transport and fluvial erosion effects dominate landform shapes. Those two effects of dominant surface processes can be represented by diffusion and incision models, which have been expressed by mathematical forms. In this study, we're going to combine these two models of which interactions are considered simultaneously to simulate the valley evolution on the tableland. The LiDAR DTM, possessing advantages of higher resolution and getting real terrain, help us observe fine surface features and infer spatial geometric variations, lateral slope and channel width changes, without collecting multi-period aerial photographs. In addition, we chose the Linkou Tableland in Taiwan as our study area because it has some characteristics such as flat terrain, horizontal and simple strata, and homogeneous composition of gravel to simplify assumptions in our model. The most important task in this study, however, is how to calibrate the parameters being included the model . These parameters, including diffusion coefficient (?), erosion coefficient (?), and two fitted parameters (m and n, related with drainage area and local slope respectively), usually imply essential information about landform evolution. Just like decoding the secrets of evolving processes, we'll probably deduce the generation time of valleys or estimate the surface erosion rate. Finally, we will discuss three conclusions in the end of this study: 1) The influence of interactions involving diffusion and incision effects. We also discuss the sensitivity of each numerical parameter. 2) Assessing the evolution time of valleys, even at the whole tableland, from mathematical modeling. 3) Estimating the erosion rate applied to engineering in gravel stratum.

Yeh, C.; Chan, Y.; Lin, M.

2010-12-01

301

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

PubMed

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

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

2012-12-15

302

Analysis of expressed sequence tags derived from a compatible Mycosphaerella fijiensis –banana interaction  

Microsoft Academic Search

Mycosphaerella fijiensis, a hemibiotrophic fungus, is the causal agent of black leaf streak disease, the most serious foliar disease of bananas and\\u000a plantains. To analyze the compatible interaction of M. fijiensis with Musa spp., a suppression subtractive hybridization (SSH) cDNA library was constructed to identify transcripts induced at late\\u000a stages of infection in the host and the pathogen. In addition,

Orelvis Portal; Yovanny Izquierdo; David De Vleesschauwer; Aminael Sánchez-Rodríguez; Milady Mendoza-Rodríguez; Mayra Acosta-Suárez; Bárbara Ocaña; Elio Jiménez; Monica Höfte

2011-01-01

303

Interactions between rod-like cellulose nanocrystals and xylan derivatives: A light scattering study  

Microsoft Academic Search

Interactions between rod-like cellulose nanocrystals and 2-hydroxypropyl-trimethylammonium (HPMA) xylan were investigated by polarized (DLS) and depolarized dynamic light scattering (DDLS). Cellulose nanocrystals were prepared by the controlled hydrolysis of black spruce pulp. Binary rod-like cellulose nanocrystal\\/water and ternary HPMA xylan\\/rod-like cellulose nanocrystal\\/water systems with different concentrations of cellulose nanocrystals were probed. Translational and rotational diffusion coefficients of cellulose nanocrystals in

Jae Hyun Sim; Katrin Schwikal; Thomas Heinze; Shuping Dong; Maren Roman; Alan Esker

2009-01-01

304

Interactions between hypoxia and sewage-derived contaminants on gene expression in fish embryos  

Microsoft Academic Search

Fish embryos were used to evaluate the interaction among common environmental and chemical stressors found in urban coastal environments, namely hypoxia, aryl hydrocarbon receptor (AhR) agonists, and estrogenic compounds. At the molecular level, the systems responding to these stressors share common response factors, and evidence exists for cross-talk between them. Biomarkers of exposure to these stressors, cytochrome P4501a (Cyp1a), estrogen

A. McElroy; C. Clarke; T. Duffy; B. Cheng; J. Gondek; M. Fast; K. Cooper; L. White

305

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.

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

2013-01-01

306

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

PubMed

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

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

2014-08-01

307

Self-Assembly and Lipid Interactions of Diacylglycerol Lactone Derivatives Studied at the Air/Water Interface  

PubMed Central

Synthetic diacylglycerol lactones (DAG-lactones) have been shown to be effective modulators of critical cellular signaling pathways. The biological activity of these amphiphilic molecules depends in part upon their lipid interactions within the cellular plasma membrane. This study explores the thermodynamic and structural features of DAG-lactone derivatives and their lipid interactions at the air/water interface. Surface-pressure/area isotherms and Brewster angle microscopy revealed the significance of specific side-groups attached to the terminus of a very rigid 4-(2-phenylethynyl) benzoyl chain of the DAG-lactones, which affected both the self-assembly of the molecules and their interactions with phospholipids. The experimental data highlight the formation of different phases within mixed DAG-lactone/phospholipid monolayers and underscore the relationship between the two components in binary mixtures of different mole ratios. Importantly, the results suggest that DAG-lactones are predominantly incorporated within fluid phospholipid phases rather than in the condensed phases that form, for example, by cholesterol. Moreover, the size and charge of the phospholipid headgroups do not seem to affect DAG-lactone interactions with lipids.

Philosof-Mazor, Liron; Volinsky, Roman; Comin, Maria J.; Lewin, Nancy E.; Kedei, Noemi; Blumberg, Peter M.; Marquez, Victor E.; Jelinek, Raz

2009-01-01

308

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

309

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

SciTech Connect

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

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

2004-08-01

310

Echocardiographic Parameters in Patients with Pulmonary Arterial Hypertension: Correlations with Right Ventricular Ejection Fraction Derived from Cardiac Magnetic Resonance and Hemodynamics  

PubMed Central

Background Echocardiography is the most convenient method used to evaluate right ventricular function, and several echocardiographic parameters were studied in previous studies. But the value of these parameters to assess the right ventricular function in patients with pulmonary arterial hypertension (PAH) has not been well defined. Methods Patients with PAH were observed prospectively. Right heart catheterization, echocardiography and cardiac magnetic resonance (CMR) were performed within 1 week interval. The correlations between echocardiographic parameters and right ventricular ejection fraction (RVEF) derived from CMR as well as hemodynamics were analyzed. Results Thirty patients were enrolled including 24 with idiopathic PAH, 5 with PAH associated with connective tissue diseases and 1 with hereditary PAH. All echocardiographic parameters except right ventricular myocardial performance index (RVMPI) correlated significantly with RVEF (tricuspid annual plane systolic excursion [TAPSE], r?=?0.440, P?=?0.015; tricuspid annular systolic excursion velocity [S’], r?=?0.444, P?=?0.016; isovolumic acceleration [IVA], r?=?0.600, P?=?0.001; right ventricular fraction area change [RVFAC], r?=?0.416, P?=?0.022; ratio of right ventricular transverse diameter to left ventricular transverse diameter [RVETD/LVETD], r?=??0.649, P<0.001; RVMPI, r?=??0.027, P?=?0.888). After adjusted for mean right atrial pressure, mean pulmonary arterial pressure and pulmonary vascular resistance (PVR), only IVA and RVETD/LVETD could independently predict RVEF. Four echocardiographic parameters displayed significant correlations with PVR (TAPSE, r?=??0.615, P<0.001; S’, r?=??0.557, P?=?0.002; RVFAC, r?=??0.454, P?=?0.012; RVETD/LVETD, r?=?0.543, P?=?0.002). Conclusions The echocardiographic parameters IVA and RVETD/LVETD can reflect RVEF independently regardless of hemodynamics in patients with PAH. In addition, TAPSE, S’, RVFAC and RVETD/LVETD can also reflect PVR in PAH patients.

Yang, Tao; Liang, Yu; Zhang, Yan; Gu, Qing; Chen, Guo; Ni, Xin-Hai; Lv, Xiu-Zhang; Liu, Zhi-Hong; Xiong, Chang-Ming; He, Jian-Guo

2013-01-01

311

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

312

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

313

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

314

Correlation between optical coherence tomography-derived assessments of lower tear meniscus parameters and clinical features of dry eye disease  

PubMed Central

Purpose To measure the correlation between subjective symptom score, conventional clinical tests, and Fourier-domain optical coherence tomography (FD-OCT) of lower tear meniscus parameters in patients with dry eye disease. Methods Eighteen patients with dry eye disease requiring medical therapy and/or punctal occlusion were recruited for this prospective, nonrandomized, observational case series. Severity of symptoms of dry eye disease was assessed using the Indiana Dry Eye Questionnaire 2002. Clinical assessments were completed using slit-lamp biomicroscopy, rose bengal dye staining, fluorescein tear break-up time (TBUT), and 5-minute Schirmer’s test with topical anesthesia. The lower tear meniscus was imaged using a FD-OCT system with 5-?m axial resolution and measured manually by a masked grader using computer calipers. Correlation was assessed using Spearman’s correlation coefficient (?). Results The mean scaled symptom score was 58 ± 21 (±SD), with a range of 0 to 100. Vital staining test averaged 1.7 ± 3.4, TBUT averaged 4.4 ± 1.8 seconds, and Schirmer’s tests averaged 10.2 ± 8.1 mm. As determined by OCT, the meniscus height was 228 ± 153 ?m, depth was 127 ± 79 ?m, and cross-sectional area was 0.018 ± 0.021 mm2. OCT meniscus area was negatively correlated with the symptom questionnaire score (P < 0.01) and positively correlated with Schirmer’s test results (P < 0.01). There was no significant correlation between symptom score and rose bengal staining, TBUT, or Schirmer’s test results (P > 0.01). Conclusions Lower tear meniscus measurement with FD-OCT is an objective, noninvasive test that correlates well with symptoms of dry eye disease and the Schirmer’s test.

Nguyen, Pho; Huang, David; Li, Yan; Sadda, Srinivas R.; Ramos, Sylvia; Pappuru, Rajeev R.; Yiu, Samuel C.

2011-01-01

315

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

316

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

317

Model membrane interaction and DNA-binding of antimicrobial peptide Lasioglossin II derived from bee venom.  

PubMed

Lasioglossins, a new family of antimicrobial peptide, have been shown to have strong antimicrobial activity with low haemo-lytic and mast cell degranulation activity, and exhibit cytotoxic activity against various cancer cells in vitro. In order to understand the active conformation of these pentadecapeptides in membranes, we have studied the interaction of Lasioglossin II (LL-II), one of the members of Lasioglossins family with membrane mimetic micelle Dodecylphosphocholine (DPC) by fluorescence, Circular Dichroism (CD) and two dimensional (2D) (1)H NMR spectroscopy. Fluorescence experiments provide evidence of interaction of the N-terminal tryptophan residue of LL-II with the hydrophobic core of DPC micelle. CD results show an extended chain conformation of LL-II in water which is converted to a partial helical conformation in the presence of DPC micelle. Moreover we have determined the first three-dimensional NMR structure of LL-II bound to DPC micelle with rmsd of 0.36Å. The solution structure of LL-II shows hydrophobic and hydrophilic core formation in peptide pointing towards different direction in the presence of DPC. This amphipathic structure may allow this peptide to penetrate deeply into the interfacial region of negatively charged membranes and leading to local membrane destabilization. Further we have elucidated the DNA binding ability of LL-II by agarose gel retardation and fluorescence quenching experiments. PMID:23159628

Bandyopadhyay, Susmita; Lee, Meryl; Sivaraman, J; Chatterjee, Chiradip

2013-01-01

318

[The interaction of NS3 protein of hepatitis C virus with polymethylen derivatives of nucleic bases].  

PubMed

NS3 protein of hepatitis C virus plays the key role in the virus functioning. It possesses three enzymatic activities, namely protease activity, associated with N-terminal domain of the protein, and helicase/NTPase activities specific for C-terminal domain. Here, the effect of some polimethylenic derivatives of the nucleic bases on helicase and ATPase enzyme activities has been studied. Several of compounds tested displayed inhibitory activity towards NS3 helicase. However, most compounds demonstrated strong activating effect on ATPase activity of the enzyme as well as several other ATPases. The ATPase activating mechanism was not described earlier. The activation potency of the compounds depended on substrate/activator concentration ratio, and was maximal at the 1000:1. The activation mechanism scheme that allows us to explain phenomena observed is proposed. PMID:21290826

Mukovnia, A V; Komissarov, V V; Kritsyn, A M; Mit'kevich, V A; Tunitskaia, V L; Kochetkov, S N

2010-01-01

319

Binding interactions of porphyrin derivatives with Ca2+ ATPase of sarcoplasmic reticulum (SERCA1a)  

PubMed Central

The use of Porphyrin derivatives as photosensitizers in Photodynamic Therapy (PDT) was investigated by means of a molecular docking study. These molecules can bind to intracellular targets such as P-type CaCa2+ ATPase of sarcoplasmic reticulum (SERCA1a). CAChe software was successfully employed for conducting the docking of Tetraphenylporphinesulfonate(TPPS), 5,10,15,20- Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) Chloride (FeTPPS) and 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) nitrosyl Chloride (FeNOTPPS) with CaCa2+ ATPase from sarcoplasmic reticulum of rabbit. The results show that FeNOTPPS forms the most stable complex with CaCa2+ ATPase.

Hai, Abdul; Kizilbash, Nadeem A; Zaidi, Syeda Huma H; Alruwaili, Jamal

2013-01-01

320

Statistically Derived Amino Acid Pair Potentials: Applications to Protein Folding and Protein-Protein Interactions  

NASA Astrophysics Data System (ADS)

A new approach to generation of tertiary conformations for a protein of given primary sequence is reviewed. Amino acid pair potentials are derived based on the hypothesis that the observed pair correlation function for a given pair of amino acids is distributed according to a Boltzmann probability distribution. Tests of this idea have been reported by Wilson and Doniach for folding of a small protein and by Sippl and collaborators for discriminating a correctly folded protein from a set of artificially misfolded models. Preliminary tests are reported on the use of this approach for the antibody-antigen docking problem and for exploration of conformation space of a polypeptide loop using a Langevin dynamics approach.

Doniach, S.

1991-10-01

321

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

322

Interactions between hypoxia and sewage-derived contaminants on gene expression in fish embryos.  

PubMed

Fish embryos were used to evaluate the interaction among common environmental and chemical stressors found in urban coastal environments, namely hypoxia, aryl hydrocarbon receptor (AhR) agonists, and estrogenic compounds. At the molecular level, the systems responding to these stressors share common response factors, and evidence exists for cross-talk between them. Biomarkers of exposure to these stressors, cytochrome P4501a (Cyp1a), estrogen receptor alpha (ER?), brain cytochrome P450 aromatase (Cyp19a2 or AromB), and hypoxia inducible factor 1 alpha (Hif-1?) mRNA expression were examined using qRT-PCR simultaneously in embryos of two well studied species, the Atlantic killifish, Fundulus heteroclitus, and the zebrafish Danio rerio. Embryos of both species were exposed to the model Cyp1a inducer ?-naphthoflavone (BNF) or 17-? estradiol (E2) under either normoxic or hypoxic (5% oxygen atmosphere) conditions and harvested prior to hatch at 9 days post fertilization (dpf) for the killifish, and 48h post fertilization (hpf) for the zebrafish. BNF significantly induced Cyp1a expression in embryos of both species with killifish embryos being more responsive (700-fold>control) than zebrafish embryos (7-100-fold>control). AromB was also significantly influenced by treatment, but to a lesser extent, with mean expression levels increased by less than two-fold over control values in response to E2, and in one case upregulated by BNF. ER? and Hif-1? were constitutively expressed in embryos of both species, but expression was unaffected by exposure to either BNF or E2. Hypoxic conditions downregulated AromB expression strongly in killifish but not in zebrafish embryos. The impact of hypoxia on expression of other genes in either species was inconsistent, although an interactive effect between hypoxia and BNF on several of the genes evaluated was observed. These data are the first to examine expression patterns of these important environmental response genes together in embryos of two important model fish species. The results support the use of Cyp1a expression as a biomarker of AhR agonists in fish embryos, and indicate that AromB may be more responsive than ER? to estrogenic chemicals at this stage in development. Hif-1? expression was not found to be a good biomarker of hypoxic exposure in either killifish or zebrafish embryos. The interaction observed between BNF and co-exposure to hypoxia warrants further investigation. Finally killifish embryos are generally more sensitive than zebrafish embryos at this stage of development supporting their use in environmental assessments. PMID:22104699

A McElroy; Clark, Carissa; Duffy, T; Cheng, B; Gondek, J; Fast, M; Cooper, K; White, L

2012-02-01

323

Peptide labeling with photoactivatable trifunctional cadaverine derivative and identification of interacting partners by biotin transfer.  

PubMed

A new photoactivatable trifunctional cross-linker, cBED (cadaverine-2-[6-(biotinamido)-2-(p-azidobenzamido) hexanoamido]ethyl-1,3'-dithiopropionate), was synthesized by chemical conversion of sulfo-SBED (sulfosuccinimidyl-2-[6-(biotinamido)-2-(p-azidobenzamido) hexanoamido]ethyl-1,3'-dithiopropionate) with cadaverine. This cross-linker was purified by reversed-phase high-performance liquid chromatography (RP-HPLC) and characterized using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. cBED is based on sulfo-SBED that has a photoactivatable azido group, a cleavable disulfide bond for label transfer methods, and a biotin moiety for highly sensitive biotin/avidin detection. By ultraviolet (UV) light, the azido group is converted to a reactive nitrene, transforming transient bindings of interacting structures to covalent bonds. In contrast to the sulfo-N-hydroxysuccinimide (sulfo-NHS) moiety of sulfo-SBED, which attaches quite unspecifically to amino groups, cBED includes a cadaverine moiety that can be attached by transglutaminase more specifically to certain glutamine residues. For instance, thymosin ?4 can be labeled with cBED using tissue transglutaminase. By high-resolution HPLC/ESI-MS (electrospray ionization-mass spectrometry) and tandem MS (MS/MS) of the trypsin digest, it was established that glutamine residues at positions 23 and 36 were labeled, whereas Q39 showed no reactivity. The covalent binding of cBED to thymosin ?4 did not influence its G-actin sequestering activity, and the complex could be used to identify new interaction partners. Therefore, cBED can be used to better understand the multifunctional role of thymosin ?4 as well as of other proteins and peptides. PMID:24732115

App, Christine; Knop, Jana; Huff, Thomas; Seebahn, Angela; Becker, Cord-Michael; Iavarone, Federica; Castagnola, Massimo; Hannappel, Ewald

2014-07-01

324

Atorvastatin treatment modulates the interaction between leptin and adiponectin, and the clinical parameters in patients with type II diabetes  

PubMed Central

The aim of this study was to examine the effect of atorvastatin treatment on levels of leptin, adiponectin and insulin resistance, and their correlation with clinical parameters, in patients with type II diabetes. Patients with diabetes (n=394) were divided into two groups, comprising 161 patients who received 20 mg/day atorvastatin (statin group), and 233 patients who did not receive statins (statin-free group). The results showed that atorvastatin treatment of patients with diabetes was not associated with changes in leptin, adiponectin, the leptin/adiponectin (L/A) ratio or homeostasis model assessment-insulin resistance (HOMA-IR). However, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG) and total cholesterol (Tchol) were positively correlated with leptin and L/A ratio in the statin group only (P<0.05). By contrast, high-density lipoprotein cholesterol (HDL-C) showed a significant positive correlation with adiponectin in the statin and statin-free groups (P<0.05). Additionally, a positive correlation was found between HOMA-IR and glycated hemoglobin (HbA1c), and TG, in both groups, whereas Tchol was positively correlated with HOMA-IR in the statin group only (P<0.05). When multivariate analysis was performed with HOMA-IR as the dependent variable, and with adjustment for age, body mass index (BMI) and waist circumference, HbA1c was found to be a significant predictor of HOMA-IR or insulin resistance. In conclusion, atorvastatin treatment may have several effects on the interaction between leptin and adiponectin, and on clinical parameters in patients with type II diabetes.

AL-AZZAM, SAYER I.; ALKHATEEB, ASEM M.; ALZOUBI, KAREM H.; ALZAYADEEN, RAYA N.; ABABNEH, MERA A.; KHABOUR, OMAR F.

2013-01-01

325

Interactive Effects of Elevated CO2 Concentration and Irrigation on Photosynthetic Parameters and Yield of Maize in Northeast China  

PubMed Central

Maize is one of the major cultivated crops of China, having a central role in ensuring the food security of the country. There has been a significant increase in studies of maize under interactive effects of elevated CO2 concentration ([CO2]) and other factors, yet the interactive effects of elevated [CO2] and increasing precipitation on maize has remained unclear. In this study, a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed so as to obtain reliable results concerning the later effects. The Open Top Chambers (OTCs) experiment was designed to control contrasting [CO2] i.e., 390, 450 and 550 µmol·mol?1, and the experiment with 15% increasing precipitation levels was also set based on the average monthly precipitation of 5–9 month from 1981 to 2010 and controlled by irrigation. Thus, six treatments, i.e. C550W+15%, C550W0, C450W+15%, C450W0, C390W+15% and C390W0 were included in this study. The results showed that the irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize. Similarly, the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [CO2], but irrigation have a positive effect on increased of them at each [CO2] level, resulting in the water use efficiency (WUE) higher in natural precipitation treatment than irrigation treatment at elevated [CO2] levels. Irradiance-response parameters, e.g., maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were increased under elevated [CO2] and irrigation, and dark respiration (Rd) was increased as well. The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced, resulting in an improved of yield and ear characteristics except axle diameter. The study concluded by reporting that, future elevated [CO2] may favor to maize when coupled with increasing amount of precipitation in Northeast China.

Meng, Fanchao; Zhang, Jiahua; Yao, Fengmei; Hao, Cui

2014-01-01

326

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

327

Robustness of quantitative compressive sensing MRI: The effect of random undersampling patterns on derived parameters for DCE- and DSC-MRI  

PubMed Central

Compressive sensing (CS) in Cartesian magnetic resonance imaging (MRI) involves random partial Fourier acquisitions. The random nature of these acquisitions can lead to variance in reconstruction errors. In quantitative MRI, variance in the reconstructed images translates to an uncertainty in the derived quantitative maps. We show that for a spatially regularized 2×-accelerated human breast CS DCE-MRI acquisition with a 1922 matrix size, the coefficients of variation (CoVs) in voxel-level parameters due to the random acquisition are 1.1%, 0.96%, and 1.5% for the tissue parameters Ktrans, ve, and vp, with an average error in the mean of ?2.5%, ?2.0%, and ?3.7%, respectively. Only 5% of the acquisition schemes had a systematic underestimation larger than than 4.2%, 3.7%, and 6.1%, respectively. For a 2×-accelerated rat brain CS DSC-MRI study with a 642 matrix size, the CoVs due to the random acquisition were 19%, 9.5%, and 15% for the cerebral blood flow and blood volume and mean transit time, respectively, and the average errors in the tumor mean were 9.2%, 0.49%, and ?7.0%, respectively. Across 11 000 different CS reconstructions, we saw no outliers in the distribution of parameters, suggesting that, despite the random undersampling schemes, CS accelerated quantitative MRI may have a predictable level of performance.

Smith, David. S.; Li, Xia; Gambrell, James V.; Arlinghaus, Lori R.; Quarles, C. Chad; Yankeelov, Thomas E.; Welch, E. Brian

2012-01-01

328

Interactions between rod-like cellulose nanocrystals and xylan derivatives: A light scattering study  

NASA Astrophysics Data System (ADS)

Interactions between rod-like cellulose nanocrystals and 2-hydroxypropyl-trimethylammonium (HPMA) xylan were investigated by polarized (DLS) and depolarized dynamic light scattering (DDLS). Cellulose nanocrystals were prepared by the controlled hydrolysis of black spruce pulp. Binary rod-like cellulose nanocrystal/water and ternary HPMA xylan/rod-like cellulose nanocrystal/water systems with different concentrations of cellulose nanocrystals were probed. Translational and rotational diffusion coefficients of cellulose nanocrystals in water are (4.8 ± 0.4) x 10-8 cm^2s-1 and (526 ± 20) s-1, respectively, and calculated lengths and diameters for nanocrystals are comparable to those of cellulose whiskers from cotton. At high cellulose nanocrystal concentrations, DDLS studies in ternary systems provide translational and rotational diffusion coefficients. However, at low cellulose nanocrystal concentrations, DDLS studies of ternary systems do not yield rotational diffusion coefficients. This behavior is attributed to bridging between polymer chains that causes non-linear deviation on standard decay rate (?) versus scattering vector magnitude (q^2) plots.

Sim, Jae Hyun; Schwikal, Katrin; Heinze, Thomas; Dong, Shuping; Roman, Maren; Esker, Alan

2009-03-01

329

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.

Pina-Vazquez, Carolina; Reyes-Lopez, Magda; Ortiz-Estrada, Guillermo; de la Garza, Mireya; Serrano-Luna, Jesus

2012-01-01

330

The fd phage and a peptide derived from its p8 coat protein interact with the HIV1 Tat-NLS and inhibit its biological functions  

Microsoft Academic Search

Filamentous fd bacteriophages are used to construct phage-display peptide libraries, which have been instrumental in selecting peptides that interact with specific domains within target molecules. Here we demonstrate that the fd bacteriophage itself, as well as NTP8 – a synthetic peptide derived from it and bearing amino acids 1–20 of the phage p8 protein – interact with the nuclear localization

A. Krichevsky; M. Rusnati; A. Bugatti; E. Waigmann; S. Shohat; A. Loyter

2005-01-01

331

Estimation of a common effect parameter from follow-up data when there is no mechanistic interaction.  

PubMed

In a stratified analysis, the results from different strata if homogeneity assumption is met are pooled together to obtain a single summary estimate for the common effect parameter. However, the effect can appear homogeneous across strata using one measure but heterogeneous using another. Consequently, two researchers analyzing the same data can arrive at conflicting conclusions if they use different effect measures. In this paper, the author draws on the sufficient component cause model to develop a stratified-analysis method regarding a particular effect measure, the 'peril ratio'. When there is no mechanistic interaction between the exposure under study and the stratifying variable (i.e., when they do not work together to complete any sufficient cause), the peril ratio is constant across strata. The author presents formulas for the estimation of such a common peril ratio. Three real data are re-analyzed for illustration. When the data is consistent with peril-ratio homogeneity in a stratified analysis, researchers can use the formulas in this paper to pool the strata. PMID:24466062

Lee, Wen-Chung

2014-01-01

332

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

333

Statistical analysis of multipole-model-derived structural parameters and charge-density properties from high-resolution X-ray diffraction experiments.  

PubMed

A comprehensive analysis of various properties derived from multiple high-resolution X-ray diffraction experiments is reported. A total of 13 charge-density-quality data sets of ?-oxalic acid dihydrate (C2H2O4·2H2O) were subject to Hansen-Coppens-based modelling of electron density. The obtained parameters and properties were then statistically analysed yielding a clear picture of their variability across the different measurements. Additionally, a computational approach (CRYSTAL and PIXEL programs) was utilized to support and examine the experimental findings. The aim of the study was to show the real accuracy and interpretation limits of the charge-density-derived data. An investigation of raw intensities showed that most of the reflections (60-70%) fulfil the normality test and the lowest ratio is observed for weak reflections. It appeared that unit-cell parameters are determined to the order of 10(-3)?Å (for cell edges) and 10(-2)?° (for angles), and compare well with the older studies of the same compound and with the new 100?K neutron diffraction data set. Fit discrepancy factors are determined within a 0.5% range, while the residual density extrema are about ±0.16?(3)?e?Å(-3). The geometry is very well reproducible between different data sets. Regarding the multipole model, the largest errors are present on the valence shell charge-transfer parameters. In addition, symmetry restrictions of multipolar parameters, with respect to local coordinate systems, are well preserved. Standard deviations for electron density are lowest at bond critical points, being especially small for the hydrogen-bonded contacts. The same is true for kinetic and potential energy densities. This is also the case for the electrostatic potential distribution, which is statistically most significant in the hydrogen-bonded regions. Standard deviations for the integrated atomic charges are equal to about 0.1?e. Dipole moments for the water molecule are comparable with the ones presented in various earlier studies. The electrostatic energies should be treated rather qualitatively. However, they are quite well correlated with the PIXEL results. PMID:24419172

Kami?ski, Rados?aw; Domaga?a, S?awomir; Jarzembska, Katarzyna N; Hoser, Anna A; Sanjuan-Szklarz, W Fabiola; Gutmann, Matthias J; Makal, Anna; Mali?ska, Maura; B?k, Joanna M; Wo?niak, Krzysztof

2014-01-01

334

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

335

Three-dimensional speckle tracking echocardiography-derived left atrial strain parameters are reduced in patients with atrial fibrillation (results from the MAGYAR-path study).  

PubMed

Objective: Three-dimensional (3D) speckle tracking echocardiography (3DSTE) is a novel imaging modality for assessing cardiac function. We aimed to analyze left atrial (LA) function using 3DSTE in patients with atrial fibrillation (AF). Methods: 3DSTE was performed in 20 patients prior to their pulmonary vein isolation for AF. Every patient underwent a complete two-dimensional echocardiographic study at the same time. 3DSTE-derived circumferential (CS), longitudinal (LS), radial (RS), 3D (3DS), and area strain (AS) values were measured in the basal (b), mid (m), and superior (s) regions of the LA. 3DSTE-defined maximal (LAmax ) and minimal LA volumes (LAmin ) and LA total emptying fraction were calculated automatically. Eleven randomly selected age- and gender-matched healthy volunteers served as controls. Results: Patients with AF had significantly larger LAmax and LAmin and reduced LS, RS and CS.3DS and AS were significantly lower throughout the LA in cases with AF (3DS-b, -m, -s [AF patients vs. controls]: -18 ± 8% vs. -29 ± 8%, P = 0.001; -14 ± 6% vs. -22 ± 7%, P = 0.002; -10 ± 7% vs. -20 ± 9%, P = 0.002; AS-b, -m, -s [AF patients vs. controls]: 35 ± 15% vs. 52 ± 13%, P = 0.004; 50 ± 21% vs. 72 ± 19%, P = 0.009; 31 ± 21% vs. 65 ± 27%, P < 0.0001, respectively). Conclusions: 3DSTE-derived "uni-dimensional" LS, RS, CS, as well as novel strain parameters (3DS, AS) are significantly reduced in patients with AF compared to matched controls. 3DS and AS might be new strain parameters providing further insights into the alterations of LA function in patients developing AF. PMID:23659362

Chadaide, Számi; Domsik, Péter; Kalapos, Anita; Sághy, László; Forster, Tamás; Nemes, Attila

2013-10-01

336

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

PubMed

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

Huang, Sheng-You; Zou, Xiaoqin

2014-04-01

337

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

PubMed Central

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

Huang, Sheng-You; Zou, Xiaoqin

2014-01-01

338

Combined experimental and quantum chemical investigation of chiroptical properties of nicotinamide derivatives with and without intramolecular cation-pi interactions.  

PubMed

The circular dichroism (CD) spectra of neutral and cationic nicotinamide derivatives were experimentally examined in solution and in the solid state to show dramatic differences in the two phases and appreciable dependence on temperature and solvent. The CD spectrum of neutral nicotinamide 1 in solution was reproduced theoretically by averaging the theoretical spectra calculated for all of the extended and folded conformers (s-trans-G(+), s-cis-G(+), s-trans-T, and s-cis-T) weighted by their population. The preference for the folded, over the extended, conformers in less polar solvent was indicated by the calculation and confirmed experimentally by the analysis of specific rotations. Theoretical CD spectrum calculated for the conformer found in the X-ray structural analysis (s-cis-T) well reproduced the experimental CD spectrum measured in the solid state. Introducing cation-pi interactions by N-methylation of 1 to give 1-Me(+) led to dramatic changes in CD spectrum. Nevertheless, the experimental CD spectrum of 1-Me(+) was well reproduced by averaging the theoretical spectra calculated for a pair of most stable conformers (s-cis-G(+) and s-trans-G(+)) of 1-Me(+). The CD spectrum calculated for the s-trans-G(+) conformer, which was found in the X-ray crystallographic analysis, did not agree with the experimental one. The theoretical spectra were better reproduced in general by the more sophisticated RI-CC2 method, but the conventional TD-DFT method also gave acceptable results. This allowed us to successfully calculate the larger derivative 2-Me(+), for which the RI-CC2 method was not practically applicable. These results show that the structure/conformation may vary with the conditions employed (e.g., by altering the solvent or phase) and thus the experimental analysis under the identical condition is essential for a serious structural study. The present study on a series of nicotinamide derivatives 1, 1-Me(+), and 2-Me(+) with and without cation-pi interactions demonstrates that the combination of experimental and theoretical chiroptical methods is capable of providing reliable structural/conformational information in solution phase, which is complementary to the X-ray crystallographic structure in the solid state. PMID:19719320

Shimizu, Akinori; Mori, Tadashi; Inoue, Yoshihisa; Yamada, Shinji

2009-07-30

339

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

340

Interaction of zearalenone and soybean isoflavone in diets on the growth performance, organ development and serum parameters in prepubertal gilts.  

PubMed

The aim of the present research was to determine the interactive effect of zearalenone (ZEA) and soybean isoflavone (ISO) on the growth performance, development of organs and serum parameters in prepubertal gilts. Ninety 75-day-old female pigs (Duroc × Landrace × Yorkshire, 26.5 ± 0.60 kg) were randomly allocated to nine diet treatments during the 21-day study. The experiment employed a 3 × 3 factorial design using a non-soybean meal diet with the addition of 0, 0.5 or 2.0 mg/kg ZEA and 0, 300 or 600 mg/kg ISO. The results indicated that simultaneous addition of ZEA and ISO had no significant influence on the growth performance in prepubertal gilts. Zearalenone with 2 mg/kg increased (p < 0.05) the relative weight of the reproductive organs (including uterus and vagina) but had no obvious effects (p > 0.05) on the relative weight of the heart, liver, lung, kidney and spleen. Isoflavone at 600 mg/kg could offset the increased weight of the reproductive organs induced by ZEA. Simultaneous addition of ZEA and ISO to prepubertal gilts increased the level of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase in the serum (p < 0.05) at day 14 but their levels decreased (p < 0.05) over time. Zearalenone increased the level of malondialdehyde and decreased the concentrations of superoxide dismutase and glutathione peroxidase (p < 0.05) in the serum. The results suggested that ISO added to diets at 600 mg/kg could reduce the increase in the relative weight of reproductive organs and relieve the oxidative stress induced by ZEA added at 2 mg/kg during the growth phase in prepubertal gilts. PMID:21883496

Wang, D F; Zhang, N Y; Peng, Y Z; Qi, D S

2012-10-01

341

Evaluation of unified interaction parameter model parameters for calculating activities of ferromanganese alloys: Mn-Fe-C, Mn-Fe-Si, Mn-C-Si, and Mn-Fe-C-Si systems  

Microsoft Academic Search

Interaction parameters for Mn-based alloys were evaluated using both carbon solubility and activity data for species in binary\\u000a and ternary manganese alloys. The parameters at 1400 °C are the following \\u000a \\u000a \\u000a \\u000a \\u000a $$\\\\begin{gathered} \\\\varepsilon _{CC} = - 4.5; \\\\varepsilon _{CCC} = 58.8; \\\\varepsilon _{FeC} = 1.5; \\\\varepsilon _{FeCC} = 2.5; \\\\ln \\\\gamma _C^0 = - 1.15 \\\\hfill \\\\\\\\ \\\\varepsilon _{CC} = 15.5;

Hongjie Li; Arthur Morris

1997-01-01

342

Derivation of Orbital Parameters of Very Low-Mass Companions in Double Stars from Radial Velocities and Observations of Space-Astrometry Missions like HIPPARCOS, DIVA and GAIA  

NASA Astrophysics Data System (ADS)

Radial velocity measurements are a well known high-precision method to obtain the orbits of extrasolar planets or brown dwarfs. However, this method is not able to determine the inclination which could be derived from astrometry. The astrometric effects of those objects are very minute, wherefore the interest of astronomers in astrometric techniques was very poor. This situation changes fundamentally since space astrometry observations are available. HIPPARCOS demonstrated the power of space astrometry and the extremely high accuracy of the DIVA, and especially the GAIA observations allows one to detect Jupiter- and Earth-like objects. The optimal estimation of the parameters of the orbit of extrasolar planets or brown dwarfs is a combination of radial velocity measurements and space astrometry observations. Here it is possible to overcome problems which are inherent in both observation methods, so space astrometry complements radial velocity observations and vice versa. This paper gives a method for the parameter estimation using both tools of measurements and shows the limits of this procedure. In addition an error assessment gives the capability of the combination of radial velocity observations and space astrometry.

Bernstein, H.-H.

343

[Flow-sensitive in-vivo 4D MR imaging at 3T for the analysis of aortic hemodynamics and derived vessel wall parameters].  

PubMed

Modern phase contrast MR imaging at 3 Tesla allows the depiction of 3D morphology as well as the acquisition of time-resolved blood flow velocities in 3 directions. In combination with state-of-the-art visualization and data processing software, the qualitative and quantitative analysis of hemodynamic changes associated with vascular pathologies is possible. The 4D nature of the acquired data permits free orientation within the vascular system of interest and offers the opportunity to quantify blood flow and derived vessel wall parameters at any desired location within the data volume without being dependent on predefined 2D slices. The technique has the potential of overcoming the limitations of current diagnostic strategies and of implementing new diagnostic parameters. In light of the recent discussions regarding the influence of the wall shear stress and the oscillatory shear index on the genesis of arteriosclerosis and dilatative vascular processes, flow-sensitive 4D MRI may provide the missing diagnostic link. Instead of relying on experience-based parameters such as aneurysm size, new hemodynamic considerations can deepen our understanding of vascular pathologies. This overview reviews the underlying methodology at 3T, the literature on time-resolved 3D MR velocity mapping, and presents case examples. By presenting the pre- and postoperative assessment of hemodynamics in a thoracic aortic aneurysm and the detailed analysis of blood flow in a patient with coarctation we underline the potential of time-resolved 3D phase contrast MR at 3T for hemodynamic assessment of vascular pathologies, especially in the thoracic aorta. PMID:17436180

Frydrychowicz, A; Markl, M; Harloff, A; Stalder, A F; Bock, J; Bley, T A; Berger, A; Russe, M F; Schlensak, C; Hennig, J; Langer, M

2007-05-01

344

PLASS: protein-ligand affinity statistical score--a knowledge-based force-field model of interaction derived from the PDB.  

PubMed

We have developed PLASS (Protein-Ligand Affinity Statistical Score), a pair-wise potential of mean-force for rapid estimation of the binding affinity of a ligand molecule to a protein active site. This scoring function is derived from the frequency of occurrence of atom-type pairs in crystallographic complexes taken from the Protein Data Bank (PDB). Statistical distributions are converted into distance-dependent contributions to the Gibbs free interaction energy for 10 atomic types using the Boltzmann hypothesis, with only one adjustable parameter. For a representative set of 72 protein-ligand structures, PLASS scores correlate well with the experimentally measured dissociation constants: a correlation coefficient R of 0.82 and RMS error of 2.0 kcal/mol. Such high accuracy results from our novel treatment of the volume correction term, which takes into account the inhomogeneous properties of the protein-ligand complexes. PLASS is able to rank reliably the affinity of complexes which have as much diversity as in the PDB. PMID:15562990

Ozrin, V D; Subbotin, M V; Nikitin, S M

2004-04-01

345

Interactions among the red deer ( Cervus elaphus, L.) population, meteorological parameters and new growth of the natural regenerated forest in Snežnik, Slovenia  

Microsoft Academic Search

Following a preliminary study (Stankovski et al., Ecol. Modelling, 108, 1998), we use machine learning techniques to conduct a more detailed analysis of the interactions among the red deer population, meteorological parameters and new forest growth. We use the machine learning program M5 (Quinlan, Proc. 10th Int. Conf. Machine Learning, Morgan Kaufmann, San Mateo CA, 1993) that learns regression trees

Marko Debeljak; Sašo Džeroski; Miha Adami?

1999-01-01

346

Colorimetric detection of platelet-derived growth factors through competitive interactions between proteins and functional gold nanoparticles.  

PubMed

We have developed a colorimetric assay-using aptamer modified 13-nm gold nanoparticles (Apt-Au NPs) and fibrinogen adsorbed Au NPs (Fib-Au NPs, 56nm)-for the highly selective and sensitive detection of platelet-derived growth factors (PDGF). Apt-Au NPs and Fib-Au NPs act as recognition and reporting units, respectively. PDGF-binding-aptamer (Apt(PDGF)) and 29-base-long thrombin-binding-aptamer (Apt(thr29)) are conjugated with Au NPs to prepare functional Apt-Au NPs (Apt(PDGF)/Apt(thr29)-Au NPs) for specific interaction with PDGF and thrombin, respectively. Thrombin interacts with Fib-Au NPs in solutions to catalyze the formation of insoluble fibrillar fibrin-Au NPs agglutinates through the polymerization of the unconjugated and conjugated fibrinogen. The activity of thrombin is suppressed once it interacts with the Apt(PDGF)/Apt(thr29)-Au NPs. The suppression decreases due to steric effects through the specific interaction of PDGF with Apt(PDGF), occurring on the surfaces of Apt(PDGF)/Apt(thr29)-Au NPs. Under optimal conditions [Apt(PDGF)/Apt(thr29)-Au NPs (25pM), thrombin (400pM) and Fib-Au NPs (30pM)], the Apt(PDGF)/Apt(thr29)-Au NPs/Fib-Au NPs probe responds linearly to PDGF over the concentration range of 0.5-20nM with a correlation coefficient of 0.96. The limit of detection (LOD, signal-to-noise ratio=3) for each of the three PDGF isoforms is 0.3nM in the presence of bovine serum albumin at 100?M. When using the Apt(PDGF)/Apt(thr29)-Au NPs as selectors for the enrichment of PDGF and for the removal of interferences from cell media, the LOD for PDGF provided by this probe is 35pM. The present probe reveals that the concentration of PDGF in the three cell media is 230 (±20)pM, showing its advantages of simplicity, sensitivity, and specificity. PMID:21900002

Lin, Tzu-En; Chen, Wei-His; Shiang, Yen-Chun; Huang, Chih-Ching; Chang, Huan-Tsung

2011-11-15

347

ODPEVP: A program for computing eigenvalues and eigenfunctions and their first derivatives with respect to the parameter of the parametric self-adjoined Sturm-Liouville problem  

NASA Astrophysics Data System (ADS)

A FORTRAN 77 program is presented for calculating with the given accuracy eigenvalues, eigenfunctions and their first derivatives with respect to the parameter of the parametric self-adjoined Sturm-Liouville problem with the parametric third type boundary conditions on the finite interval. The program calculates also potential matrix elements - integrals of the eigenfunctions multiplied by their first derivatives with respect to the parameter. Eigenvalues and matrix elements computed by the ODPEVP program can be used for solving the bound state and multi-channel scattering problems for a system of the coupled second-order ordinary differential equations with the help of the KANTBP programs [O. Chuluunbaatar, A.A. Gusev, A.G. Abrashkevich, A. Amaya-Tapia, M.S. Kaschiev, S.Y. Larsen, S.I. Vinitsky, Comput. Phys. Commun. 177 (2007) 649-675; O. Chuluunbaatar, A.A. Gusev, S.I. Vinitsky, A.G. Abrashkevich, Comput. Phys. Commun. 179 (2008) 685-693]. As a test desk, the program is applied to the calculation of the potential matrix elements for an integrable 2D-model of three identical particles on a line with pair zero-range potentials, a 3D-model of a hydrogen atom in a homogeneous magnetic field and a hydrogen atom on a three-dimensional sphere. Program summaryProgram title: ODPEVP Catalogue identifier: AEDV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3001 No. of bytes in distributed program, including test data, etc.: 24 195 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Intel Xeon EM64T, Alpha 21264A, AMD Athlon MP, Pentium IV Xeon, Opteron 248, Intel Pentium IV Operating system: OC Linux, Unix AIX 5.3, SunOS 5.8, Solaris, Windows XP RAM: depends on the number and order of finite elements; the number of points; and the number of eigenfunctions required. Test run requires 4 MB Classification: 2.1, 2.4 External routines: GAULEG [3] Nature of problem: The three-dimensional boundary problem for the elliptic partial differential equation with an axial symmetry similar to the Schrödinger equation with the Coulomb and transverse oscillator potentials is reduced to the two-dimensional one. The latter finds wide applications in modeling of photoionization and recombination of oppositively charged particles (positrons, antiprotons) in the magnet-optical trap [4], optical absorption in quantum wells [5], and channeling of likely charged particles in thin doped films [6,7] or neutral atoms and molecules in artificial waveguides or surfaces [8,9]. In the adiabatic approach [10] known in mathematics as Kantorovich method [11] the solution of the two-dimensional elliptic partial differential equation is expanded over basis functions with respect to the fast variable (for example, angular variable) and depended on the slow variable (for example, radial coordinate ) as a parameter. An averaging of the problem by such a basis leads to a system of the second-order ordinary differential equations which contain potential matrix elements and the first-derivative coupling terms (see, e.g., [12,13,14]). The purpose of this paper is to present the finite element method procedure based on the use of high-order accuracy approximations for calculating eigenvalues, eigenfunctions and their first derivatives with respect to the parameter of the parametric self-adjoined Sturm-Liouville problem with the parametric third type boundary conditions on the finite interval. The program developed calculates potential matrix elements - integrals of the eigenfunctions multiplied by their derivatives with respect to the parameter. These matrix elements can be used for solving the bound state and multi-channel scattering problems for a system of the coupled second-order ordinary differential equations with the help of the KANTBP programs [1,2]. Solution method: The parametric se

Chuluunbaatar, O.; Gusev, A. A.; Vinitsky, S. I.; Abrashkevich, A. G.

2009-08-01

348

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.

2014-01-01

349

Interaction of cinnamic acid derivatives with commercial hypoglycemic drugs on 2-deoxyglucose uptake in 3T3-L1 adipocytes.  

PubMed

Hydroxycinnamic acid derivatives are naturally occurring substances found in fruits, vegetables, and flowers and are consumed as dietary phenolic compounds. The effect of cinnamic acid, ferulic acid, p-coumaric acid, eugenol, chlorogenic acid, and caffeic acid, alone and in combination with two commercial oral hypoglycemic drugs (OHD), namely, thiazolidinedione (THZ) and metformin, on the uptake of 2-deoxyglucose (2DG) by 3T3-L1 adipocytes is studied. All of the phytochemicals other than cinnamic acid show synergistic interaction in 2DG uptake with both of the OHDs. THZ (20 ?M) in combination with ferulic acid (25 ?M) or p-coumaric acid (25 ?M) increases 2DG uptake by 7- or 6.34-fold, respectively, with respect to control, whereas metformin (20 ?M), along with ferulic acid (25 ?M) or cinnamic acid (25 ?M), increases 2DG uptake by 6.45- or 5.87-fold, respectively, when compared to control. Chlorogenic and cinnamic acids increased the expression of PPAR?, whereas other hydroxycinnamic acids enhanced the expression of PI3K, indicating different mechanisms of action between these compounds. These phytochemicals were able to reduce the expressions of the fatty acid synthase and HMG CoA reductase genes, indicating that they may be able to reduce the secondary complications caused by the accumulation of lipids. These studies suggest that hydroxycinnamic acid derivatives may be beneficial for the treatment of diabetes mellitus. They may act as a supplement with commercial drugs and may reduce the secondary complications caused by OHDs. PMID:21870829

Prabhakar, Pranav Kumar; Doble, Mukesh

2011-09-28

350

Parameters of tip-sample interactions in shear mode using a quartz tuning fork AFM with controllable Q-factor  

Microsoft Academic Search

A quartz tuning fork-based atomic force microscopy for investigating the tip-sample interactions at the nanoscale in the shear-force mode is described. Results of force interactions (damping and elastic forces) can be obtained from the amplitude-phase-distance spectroscopy measurements made with a tuning fork with a tungsten tip and a sample surface. The influence of the interaction between tip and sample using

Vo Thanh Tung; S. A. Chizhik; Tran Xuan Hoai

2009-01-01

351

Parameters of tip–sample interactions in shear mode using a quartz tuning fork AFM with controllable Q-factor  

Microsoft Academic Search

A quartz tuning fork-based atomic force microscopy for investigating the tip–sample interactions at the nanoscale in the shear-force\\u000a mode is described. Results of force interactions (damping and elastic forces) can be obtained from the amplitude-phase-distance\\u000a spectroscopy measurements made with a tuning fork with a tungsten tip and a sample surface. The influence of the interaction\\u000a between tip and sample using

Vo Thanh Tung; S. A. Chizhik; Tran Xuan Hoai

2009-01-01

352

Interaction of the Vibrio cholerae cytolysin (VCC) with cholesterol, some cholesterol esters, and cholesterol derivatives: a TEM study.  

PubMed

The Vibrio cholerae cytolysin (VCC) 63-kDa monomer has been shown to interact in aqueous suspension with cholesterol microcystals to produce a ring/pore-like heptameric oligomer approximately 8 nm in outer diameter. Transmission electron microscopy data were produced from cholesterol samples adsorbed to carbon support films, spread across the holes of holey carbon films, and negatively stained with ammonium molybdate. The VCC oligomers initially attach to the edge of the stacked cholesterol bilayers and with increasing time cover the two planar surfaces. VCC oligomers are also released into solution, with some tendency to cluster, possibly via the hydrophobic membrane-spanning domain. At the air/water interface, the VCC oligomers are likely to be selectively oriented with the hydrophobic domain facing the air. Despite some molecular disorder/plasticity within the oligomers, multivariate statistical analysis and rotational self-correlation using IMAGIC-5 strongly suggest the presence of sevenfold rotational symmetry. To correlate the electron microscopy data with on-going biochemical and permeability studies using liposomes of varying lipid composition, the direct interaction of VCC with several cholesterol derivatives and other steroids has been examined. 19-Hydroxycholesterol and 7 beta-hydroxycholesterol both induce VCC oligomerization. beta-Estradiol, which does not possess an aliphatic side chain, also efficiently induces VCC oligomer formation, as does cholesteryl acetate. Cholesteryl stearate and oleate and the C22 (2-trifluoroacetyl)naphthyloxy analogue of cholesterol fail to induce VCC oligomerization, but binding of the monomer to the surface of these steroids does occur. Stigmasterol has little tendency to induce oligomer formation, and oligomers are largely confined to the edge of the bilayers; ergosterol has even less oligomerization ability. Attempts to solubilize and stabilize the VCC oligomers from cholesterol suspensions have been pursued using the neutral surfactant octylglucoside. Although individual solubilized oligomers have been defined which exhibit a characteristic cytolysin channel conformation in the side-on orientation, a tendency remains for the oligomers to cluster via their hydrophobic domains. PMID:12406694

Harris, J Robin; Bhakdi, Sucharit; Meissner, Ulrich; Scheffler, Dirk; Bittman, Robert; Li, Guoqing; Zitzer, Alexander; Palmer, Michael

2002-08-01

353

Solubility and binding properties of PEGylated lysozyme derivatives with increasing molecular weight on hydrophobic-interaction chromatographic resins.  

PubMed

Dynamic binding capacities and resolution of PEGylated lysozyme derivatives with varying molecular weights of poly (ethylene) glycol (PEG) with 5 kDa, 10 kDa and 30 kDa for HIC resins and columns are presented. To find the optimal range for the operating conditions, solubility studies were performed by high-throughput analyses in a 96-well plate format, and optimal salt concentrations and pH values were determined. The solubility of PEG-proteins was strongly influenced by the length of the PEG moiety. Large differences in the solubilities of PEGylated lysozymes in two different salts, ammonium sulfate and sodium chloride were found. Solubility of PEGylated lysozyme derivatives in ammonium sulfate decreases with increased length of attached PEG chains. In sodium chloride all PEGylated lysozyme derivatives are fully soluble in a concentration range between 0.1 mg protein/ml and 10 mg protein/ml. The binding capacities for PEGylated lysozyme to HIC resins are dependent on the salt type and molecular weight of the PEG polymer. In both salt solutions, ammonium sulfate and sodium chloride, the highest binding capacity of the resin was found for 5 kDa PEGylated lysozyme. For both native lysozyme and 30 kDa mono-PEGylated lysozyme the binding capacities were lower. In separation experiments on a TSKgel Butyl-NPR hydrophobic-interaction column with ammonium sulfate as mobile phase, the elution order was: native lysozyme, 5 kDa mono-PEGylated lysozyme and oligo-PEGylated lysozyme. This elution order was found to be reversed when sodium chloride was used. Furthermore, the resolution of the three mono-PEGylated forms was not possible with this column and ammonium sulfate as mobile phase. In 4 M sodium chloride a resolution of all PEGylated lysozyme forms was achieved. A tentative explanation for these phenomena can be the increased solvation of the PEG polymers in sodium chloride which changes the usual attractive hydrophobic forces in ammonium sulfate to more repulsive hydration forces in this hydrotrophic salt. PMID:20570270

Müller, Egbert; Josic, Djuro; Schröder, Tim; Moosmann, Anna

2010-07-01

354

Site Response Spectral Accelerations Based on Site Specific Geologic Control of Randomization Parameters can be Higher Than Spectral Accelerations Derived Using Randomization Models Based on Larger Coefficients of Variation Derived Over Larger Areas  

NASA Astrophysics Data System (ADS)

The randomization of soil properties for use in seismic site response models is an accepted practice in seismic design. The application of this methodology in the absence of robust geologic control can result in inappropriately low design spectra. Site response spectra computed using data from a broad area and intended for site specific design were derived using randomization procedures that incorporate variability in soil unit thicknesses, depth to basalt and shear wave velocity (Coefficient of Variation = 0.39 to 0.50). The resulting spectral accelerations are 40% lower than the spectral accelerations derived using site specific geologic models based on geologic, cross hole and down hole shear wave velocities and borehole geophysical data over a smaller area (COV = 0.08 to 0.12). In this case a relatively constant depth and soil thickness of 44 feet (Vs approximately 1,300 feet per second) on basalt (Vs approximately 3,500 feet per second) across the site contrasted sharply with the previous randomization assumptions which assumed greater basalt depth variability. Although the lower site specific soil property COVs contributed to a site specific increase in ground motion amplification, the primary factor was likely the relatively flat basalt surface which produced site amplification effects exceededing the previous randomization estimates by 40%. The bias towards higher COVs seems to be driven by a need to account for aleatory uncertainty (especially in soil structure interaction modeling) and the engineering preference for smoother response spectra. Discussion and research may be needed to account for what appears to be an arbitrary increase in aleatory uncertainty to account for a decrease in epistemic uncertainty which occurs as a result of better site characterization methods and models.

Creed, R. J.

2009-05-01

355

Characterisation of the interaction of neuropilin-1 with heparin and a heparan sulfate mimetic library of heparin-derived sugars.  

PubMed

Background. Neuropilin-1 (NRP-1) is a multidomain membrane protein with soluble isoforms interacting with a complex network of other membrane receptors, their respective ligands and heparan sulfate (HS). It is involved in the development of vasculature, neural patterning, immunological responses and pathological angiogenesis. Methods. We have characterised the binding of a Fc fusion of rat NRP-1 (Fc rNRP-1) and of a soluble isoform, corresponding to the first four extracellular domains of human NRP-1, shNRP-1, using optical biosensor-based binding assays with a library of heparin derivatives. Selective labelling of lysines protected upon heparin binding allowed their identification by mass spectrometry. Results. Fc rNRP-1 bound to heparin with high affinity (2.5 nM) and fast ka (9.8 × 10(6) M(-1)s(-1)). Unusually, NRP-1 bound both highly sulfated and completely desulfated stretches of heparin and exhibited a complex pattern of preferences for chemically modified heparins possessing one or two sulfate groups, e.g., it bound heparin with just a 6-O sulfate group better than heparin with any two of N-sulfate, 6-O sulfate and 2-O sulfate. Mass-spectrometry based mapping identified that, in addition to the expected the b1 domain, the a1, and c domains and the L2 linker were also involved in the interaction. In contrast, shNRP-1 bound heparin far more weakly. This could only be shown by affinity chromatography and by differential scanning fluorimetry. Discussion. The results suggest that the interaction of NRP-1 with HS is more complex than anticipated and involving a far greater extent of the protein than just the b1-b2 domains. NRP-1's preference for binding long saccharide structures suggests it has the potential to bind large segments of HS chains and so organise their local structure. In contrast, the four domain soluble isoform, shNRP-1 binds heparin weakly and so would be expected to diffuse away rapidly from the source cell. PMID:25024924

Uniewicz, Katarzyna A; Ori, Alessandro; Ahmed, Yassir A; Yates, Edwin A; Fernig, David G

2014-01-01

356

Characterisation of the interaction of neuropilin-1 with heparin and a heparan sulfate mimetic library of heparin-derived sugars  

PubMed Central

Background. Neuropilin-1 (NRP-1) is a multidomain membrane protein with soluble isoforms interacting with a complex network of other membrane receptors, their respective ligands and heparan sulfate (HS). It is involved in the development of vasculature, neural patterning, immunological responses and pathological angiogenesis. Methods. We have characterised the binding of a Fc fusion of rat NRP-1 (Fc rNRP-1) and of a soluble isoform, corresponding to the first four extracellular domains of human NRP-1, shNRP-1, using optical biosensor-based binding assays with a library of heparin derivatives. Selective labelling of lysines protected upon heparin binding allowed their identification by mass spectrometry. Results. Fc rNRP-1 bound to heparin with high affinity (2.5 nM) and fast ka (9.8 × 106 M?1s?1). Unusually, NRP-1 bound both highly sulfated and completely desulfated stretches of heparin and exhibited a complex pattern of preferences for chemically modified heparins possessing one or two sulfate groups, e.g., it bound heparin with just a 6-O sulfate group better than heparin with any two of N-sulfate, 6-O sulfate and 2-O sulfate. Mass-spectrometry based mapping identified that, in addition to the expected the b1 domain, the a1, and c domains and the L2 linker were also involved in the interaction. In contrast, shNRP-1 bound heparin far more weakly. This could only be shown by affinity chromatography and by differential scanning fluorimetry. Discussion. The results suggest that the interaction of NRP-1 with HS is more complex than anticipated and involving a far greater extent of the protein than just the b1–b2 domains. NRP-1’s preference for binding long saccharide structures suggests it has the potential to bind large segments of HS chains and so organise their local structure. In contrast, the four domain soluble isoform, shNRP-1 binds heparin weakly and so would be expected to diffuse away rapidly from the source cell.

Uniewicz, Katarzyna A.; Ori, Alessandro; Ahmed, Yassir A.; Yates, Edwin A.

2014-01-01

357

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

358

Antitumour polycyclic acridines. Part 4. Physico-chemical studies on the interactions between DNA and novel tetracyclic acridine derivatives.  

PubMed

The non-covalent interactions between a series of new tetracyclic acridine derivatives (5-11) and DNA have been studied by spectrophotometric analysis, fluorescences quenching, thermal denaturation, and circular and linear dichroism. In order to compare the extent of the DNA binding by compounds 5-11 in their neutral and cationic forms, all experiments were conducted at pH 7.4 (physiological pH) and 5.0. The results indicated that compounds 5-11 are strong DNA-binding ligands with DNA affinities comparable to that of m-AMSA (1) or even higher. They showed a stronger DNA binding activity at pH 5.0 as a result of the N-protonation of the pyridoacridine aromatic chromophore. Ethidium-DNA fluorescence assays showed an A-T base pair preference of the binding distinguishing these novel compounds from simple acridines which show a slight G-C base pair preference. Circular and linear dichroism studies indicated that the drugs bind to DNA by undergoing intercalation inside the duplex macromolecule at high DNA:drug ratios and revealed alternative binding modes at low DNA:drug ratios. PMID:9702209

Giménez-Arnau, E; Missailidis, S; Stevens, M F

1998-07-01

359

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

360

Parameters of tip-sample interactions in shear mode using a quartz tuning fork AFM with controllable Q-factor  

NASA Astrophysics Data System (ADS)

A quartz tuning fork-based atomic force microscopy for investigating the tip-sample interactions at the nanoscale in the shear-force mode is described. Results of force interactions (damping and elastic forces) can be obtained from the amplitude-phase-distance spectroscopy measurements made with a tuning fork with a tungsten tip and a sample surface. The influence of the interaction between tip and sample using the quality factor as an indicator is investigated. Furthermore, a simple model shows that the extension of a tuning fork-based AFM can be applied to quantitative analysis of the properties of the sample surface.

Thanh Tung, Vo; Chizhik, S. A.; Xuan Hoai, Tran

2009-01-01

361

Features of parameters of gamma-ray families formed from AA-interactions at superhigh energies above 1016 eV  

NASA Astrophysics Data System (ADS)

Different lateral and energetic characteristics of gamma-ray families produced in nucleus-nucleus (AA) interactions of primary cosmic rays (PCR) are studied. Primary mass composition analysis performed on the basis of "Pamir" Collaboration X-ray emulsion chambers (XREC) data by using of selection criteria of gamma-ray families originating from AA-interactions above 10 PeV. Experimental data are compared with results of MC0 algorithm based on quark-gluon string model (QGSM). Among seven considered variables, only two lateral parameters, R1E and ?, are not described by the MC0 model.

Yuldashbaev, T. S.; Nuritdinov, Kh

2013-02-01

362

Effects of material parameter on interaction length to occur optical phase conjugation via stimulated Brillouin scattering in semiconductors  

NASA Astrophysics Data System (ADS)

In the present formulation using hydrodynamic model and coupled mode scheme of plasmas the interaction length necessary to achieve optical phase conjugation is obtained from steady-state Brillouin gain coefficient for a semiconductor crystal. The analytical investigation of steady-state gain of stimulated Brillouin scattering (SBS) is made by assuming that the SBS is resulted from the nonlinear interaction of an intense electromagnetic wave with acoustic perturbation internally generated due to acousto-optic property of the semiconductor crystal. Numerical estimates confirm that when cyclotron frequency is tuned with pump frequency, interaction length is found to be nearly 10 m smaller than that obtained in absence of magnetic filed. Pump intensity and free carrier concentration both helpful in reducing the required interaction length.

Nimje, Nilesh; Yadav, Nishchhal; Ghosh, S.

2012-01-01

363

Binding Rather Than Metabolism May Explain the Interaction of Two Food-Grade Lactobacillus Strains with Zearalenone and Its Derivative  -Zearalenol  

Microsoft Academic Search

The interaction between two Fusarium mycotoxins, zearalenone (ZEN) and its derivative ´-zearalenol ( ´-ZOL), with two food-grade strains of Lactobacillus was investigated. The mycotoxins (2 gm l 1 ) were in- cubated with either Lactobacillus rhamnosus strain GG or L. rhamnosus strain LC705. A considerable propor- tion (38 to 46%) of both toxins was recovered from the bacterial pellet, and

Hani El-Nezami; Nektaria Polychronaki; Seppo Salminen; Hannu Mykkanen

2002-01-01

364

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

365

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

366

Trends and interactions of physical and bio-geo-chemical features in the Adriatic Sea as derived from satellite observations.  

PubMed

Time series of satellite data, generated by the AVHRR (1981-1999), CZCS (1979-1985) and SeaWiFS (1998-2002), have been used to assess trends and interactions of physical and bio-geo-chemical features in the Adriatic Sea. The images were processed to estimate Sea Surface Temperature (SST) and Chlorophyll-like Pigment Concentration (CPC). Long-term composites and climatologies were derived, using fixed geographical grids and projections. The AVHRR data show an apparent warming trend, when plotting the sequence of seasonal cycles (monthly mean SST, averaged over the whole basin) against time, due to a steady rise of summer values. Considering 3 regions (north, central and south), split into east and west sections, the northern Adriatic shows high SST fluctuations (possibly associated with the cycle of winter cooling and summer warming, typical of the relatively shallow sub-basin), while the southern Adriatic exhibits a lower variability (possibly influenced by the periodic water incoming from, and outflowing to the Ionian Sea). During summer, an east-west gradient prevails, while during winter only a general north-south gradient can be found. The SeaWiFS-derived CPC values, distributions and trends appear to be consistent with the historical CZCS record. Persistent differences in the quantitative assessment of CPC for coastal waters is due to the use of improved algorithms, less influenced by the presence of dissolved organics and suspended sediments in the water column, for the processing of SeaWiFS data. Apparent incongruities of the space and time patterns in the SeaWiFS record with respect to the reference climatology, obtained by CZCS more than a decade before, occur chiefly when considering the spring bloom in the southern Adriatic and the summer development of the north Adriatic front. The comparison of the long-term times series of satellite data shows that there is a high correlation between patterns in the thermal field and in the colour field. This suggests that different surface waters, identified by the SST index, are also traced by different ecological features, identified by the CPC index. Both indices also show a high correlation with the classical cyclonic circulation scheme of the Adriatic Sea, proposing once again an intimate relationship between the water dynamics and its bio-geo-chemistry. PMID:16271746

Barale, Vittorio; Schiller, Christian; Tacchi, Ruggero; Marechal, Cecile

2005-12-15

367

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

368

Interface interactions of osteoblasts with structured titanium and the correlation between physicochemical characteristics and cell biological parameters.  

PubMed

Cellular behavior at the interface of an implant is influenced by the material's topography. However, little is known about the correlation between the biological parameters and the physicochemical characteristics of the biomaterial. We therefore modified pure titanium surfaces by polishing, machining, blasting with glass spheres, blasting with corundum particles, and vacuum plasma spraying to give progressively higher surface roughness. The material surface was characterized by SEM, surface profiling, and electrochemical methods. We revealed a correlation for integrin expression and formation, adhesion, spreading, proliferation, and bone sialo protein expression with the physicochemical parameters of the titanium surfaces. PMID:17457937

Nebe, J G Barbara; Luethen, Frank; Lange, Regina; Beck, Ulrich

2007-05-10

369

Supplementation with a mixture of complex lipids derived from milk to growing rats results in improvements in parameters related to growth and cognition.  

PubMed

Alterations in nutritional factors during early development can exert long-term effects on growth, neural function, and associated behaviors. The lipid component of milk provides a critical nutritional source for generating both energy and essential nutrients for the growth of the newborn. The present study, therefore, investigated the hypothesis that nutritional supplementation with a complex milk lipid (CML) preparation, derived from the milk fat globule membrane rich in phospholipids and gangliosides from young rats, has beneficial effects on learning behavior and postnatal growth and development. Male Wistar rat offspring from normal pregnancies were treated from neonatal day 10 until postnatal day 80 with either vehicle or CML at a dose of 0.2% (low) and 1.0% (high) based on total food intake (n = 16 per group). Neonatal dosing was via daily oral gavage, while postweaning dosing was via gel supplementation to a standard chow diet. Animals underwent behavioral tasks related to spatial memory, learning, and cognitive function. Complex milk lipid supplementation significantly increased linear growth rate (P < .05), and the improved growth trajectory was not related to changes in body composition as quantified by dual-energy x-ray absorptiometry scanning or altered plasma lipid profiles. Moreover, this effect was not dose dependent and not attributable to the contribution to total energy intake of the CML composition. Supplementation of the CML to growing rats resulted in statistically significant improvements in parameters related to novelty recognition (P < .02) and spatial memory (P < .05) using standard behavioral techniques, but operant testing showed no significant differences between treatment groups. Supplementation with a CML containing gangliosides had positive growth and learning behavioral effects in young normal growing rats. PMID:19628110

Vickers, Mark H; Guan, Jian; Gustavsson, Malin; Krägeloh, Christian U; Breier, Bernhard H; Davison, Michael; Fong, Bertram; Norris, Carmen; McJarrow, Paul; Hodgkinson, Steve C

2009-06-01

370

Discordant effects of interleukin-2 on viral and immune parameters in human immunodeficiency virus-1-infected monocyte-derived mature dendritic cells.  

PubMed

Use of interleukin-2 (IL-2) in the immunotherapy of human immunodeficiency virus (HIV) has frequently resulted in the restoration of CD4 lymphocyte counts but not of virus-specific responses. We reasoned that the absence of reconstituted functional immune parameters could be related to the inability of IL-2 to correct HIV-induced dysfunctions in antigen-presenting cells. In this study, we used in vitro-differentiated monocyte-derived macrophages (MDMs) and mature dendritic cells (MDDCs), acutely infected with primary HIV-1 isolates, to analyse the effects of IL-2 on virus replication, co-receptor expression, and cytokine or chemokine release. Stimulation of MDMs with IL-2 had no measurable effect on HIV-1 replication, on cytokine secretion, or on CD4 and CXCR4 gene expression. Moreover, although a significant down-regulation of CCR5 mRNA expression could be repeatedly detected in MDMs, this IL-2-mediated effect was not of substantial magnitude to affect virus replication. On the other hand, IL-2 stimulation of MDDCs dramatically increased HIV-1 replication and this effect was highly evident on low-replicating, CXCR4-dependent isolates. Nevertheless, the HIV-enhancing activity of IL-2 in MDDCs was not accompanied by any measurable change in cytokine or chemokine release, in virus receptor and co-receptor mRNA accumulation, or in the surface expression of a battery of receptors implicated in virus entry, cell activation or costimulatory function. Taken together, these findings point to a role for IL-2 in inducing virus purging from dendritic cell reservoirs but indicate no relevant potential of the cytokine in restoring defective elements of innate immunity in HIV infection. PMID:12699419

Bahr, G M; Darcissac, E C A; Mouton, Y

2003-05-01

371

How short is too short for the interactions of a water potential? Exploring the parameter space of a coarse-grained water model using uncertainty quantification.  

PubMed

Coarse-grained models are becoming increasingly popular due to their ability to access time and length scales that are prohibitively expensive with atomistic models. However, as a result of decreasing the degrees of freedom, coarse-grained models often have diminished accuracy, representability, and transferability compared with their finer grained counterparts. Uncertainty quantification (UQ) can help alleviate this challenge by providing an efficient and accurate method to evaluate the effect of model parameters on the properties of the system. This method is useful in finding parameter sets that fit the model to several experimental properties simultaneously. In this work we use UQ as a tool for the evaluation and optimization of a coarse-grained model. We efficiently sample the five-dimensional parameter space of the coarse-grained monatomic water (mW) model to determine what parameter sets best reproduce experimental thermodynamic, structural and dynamical properties of water. Generalized polynomial chaos (gPC) was used to reconstruct the analytical surfaces of density, enthalpy of vaporization, radial and angular distribution functions, and diffusivity of liquid water as a function of the input parameters. With these surfaces, we evaluated the sensitivity of these properties to perturbations of the model input parameters and the accuracy and representability of the coarse-grained models. In particular, we investigated what is the optimum length scale of the water-water interactions needed to reproduce the properties of liquid water with a monatomic model with two- and three-body interactions. We found that there is an optimum cutoff length of 4.3 Å, barely longer than the size of the first neighbor shell in water. As cutoffs deviate from this optimum value, the ability of the model to simultaneously reproduce the structure and thermodynamics is severely diminished. PMID:24605768

Jacobson, Liam C; Kirby, Robert M; Molinero, Valeria

2014-07-17

372

Combined direct and remote sensing measurements of air-sea interaction parameters during the temperature front passage  

Microsoft Academic Search

The paper presents the results of the experiment CAPMOS'05 performed on an offshore oceanographic platform in the Black Sea in June 2005. Measurements on the platform were carried during June 2-20 round a clock. A set of meteorological and oceanographic parameters was measured: water and air temperature and water salinity at several levels, sea current vectors at various depths, turbulence

Natalia Y. Komarova; Irina A. Repina

2010-01-01

373

Evolution of air–sea interaction parameters during the temperature front passage: The measurements on an oceanographic platform  

Microsoft Academic Search

The paper presents the results of the experiment CAPMOS'05 performed on an offshore oceanographic platform in the Black Sea in June 2005. Measurements on the platform were carried during June 2–20 round a clock. A set of meteorological and oceanographic parameters was measured: water and air temperature and water salinity at several levels, sea current vectors at various depths, turbulence

I. A. Repina; A. M. Chukharev; Y. N. Goryachkin; N. Y. Komarova; M. N. Pospelov

2009-01-01

374

Antagonistic Interactions between Stress Factors during the Growth of Microorganisms under Conditions Simulating the Parameters of Their Natural Ecotopes  

Microsoft Academic Search

Two stress factors, hypoxia (microaerobic conditions) and a high salt concentration, if applied simultaneously to aerobic microorganisms, display an antagonistic mode of interaction. As a result, the NaCl level that is usually optimal for moderate halophiles (5–6 %) becomes optimal for the growth of weak halophiles (Rhodococcus erythropolis and Shewanella sp. CN32); the halotolerant yeast Yarrowia lypolytica acquires halophilic properties

V. G. Arzumanyan; N. A. Voronina; O. V. Geidebrekht; O. V. Shelemekh; V. K. Plakunov; S. S. Belyaev

2002-01-01

375

Fructose metabolizing enzymes in the rat liver and metabolic parameters: Interactions between dietary copper, type of carbohydrates, and gender  

Microsoft Academic Search

This study was conducted to determine the effects of nutrient interactions between dietary carbohydrates and copper levels on fructose-metabolizing hepatic enzymes in male and female rats. Male and female rats were fed diets for 5 weeks that were either adequate or deficient in copper that contained either starch or fructose. Rats of both sexes fed fructose as compared with those

Moshe J. Werman; Sam J. Bhathena

1995-01-01

376

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

377

Interaction  

NSDL National Science Digital Library

Set values for the initial position, velocity, and mass of the two particles, and click on the button "Initialize Animation" to play the animation using your specified values. Note, if m or v are too large, the particles may actually pass through one another which will seem a little strange. Note: the interaction between the particles is a "non-contact" interaction, much like the electrostatic force on two charges. Mathematically, it is actually a Hooke's law interaction.

Christian, Wolfgang; Belloni, Mario

2008-02-19

378

Ethers and esters derived from apocynin avoid the interaction between p47phox and p22phox subunits of NADPH oxidase: evaluation in vitro and in silico  

PubMed Central

NOX (NADPH oxidase) plays an important role during several pathologies because it produces the superoxide anion (O2•?), which reacts with NO (nitric oxide), diminishing its vasodilator effect. Although different isoforms of NOX are expressed in ECs (endothelial cells) of blood vessels, the NOX2 isoform has been considered the principal therapeutic target for vascular diseases because it can be up-regulated by inhibiting the interaction between its p47phox (cytosolic protein) and p22phox (transmembrane protein) subunits. In this research, two ethers, 4-(4-acetyl-2-methoxy-phenoxy)-acetic acid (1) and 4-(4-acetyl-2-methoxy-phenoxy)-butyric acid (2) and two esters, pentanedioic acid mono-(4-acetyl-2-methoxy-phenyl) ester (3) and heptanedioic acid mono-(4-acetyl-2-methoxy-phenyl) ester (4), which are apocynin derivatives were designed, synthesized and evaluated as NOX inhibitors by quantifying O2•? production using EPR (electron paramagnetic resonance) measurements. In addition, the antioxidant activity of apocynin and its derivatives were determined. A docking study was used to identify the interactions between the NOX2?s p47phox subunit and apocynin or its derivatives. The results showed that all of the compounds exhibit inhibitory activity on NOX, being 4 the best derivative. However, neither apocynin nor its derivatives were free radical scavengers. On the other hand, the in silico studies demonstrated that the apocynin and its derivatives were recognized by the polybasic SH3A and SH3B domains, which are regions of p47phox that interact with p22phox. Therefore this experimental and theoretical study suggests that compound 4 could prevent the formation of the complex between p47phox and p22phox without needing to be activated by MPO (myeloperoxidase), this being an advantage over apocynin.

Macias-Perez, Martha Edith; Martinez-Ramos, Federico; Padilla-Martinez, Itzia Irene; Correa-Basurto, Jose; Kispert, Lowell; Mendieta-Wejebe, Jessica Elena; Rosales-Hernandez, Martha Cecilia

2013-01-01

379